Search results for: solar panel efficiency technique

Authors: Adriana Anselmo Oliveira

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The present project showcases a tile work from the Franco-Portuguese artist Maria Helena Vieira da Silva (1908-1992). It is a set of 8 panels composed of figurative and geometric tiles, with extra tiles framing nearby doors and windows in a study room in the (UFRRJ, Universidade Federal Rural do Rio de Janeiro). The aforementioned work was created between 1942 and 1943, during the artist's 6 year exile in the Brazilian city. This one-of-a-kind tileset was designed and made by Vieira da Silva between 1942 and 1943. Over the years, several units were lost, which led to their replacement in the nineties. However, these replacements don't do justice to the original work of art. In 2007, a project was initiated to fully repair and maintain the set. Three panels are removed and restored, but the project is halted. To this day, the three fully restored panels remain in boxes. In 2016 a new restoration project is submitted by the (Faculdade de Belas Artes da Universidade de Lisboa) in collaboration with de (Fundacão Árpád Szenes-Vieira da Silva). There are many varied opinions on restoring and conserving older pieces of art, however, we have the moral duty to safeguard the original materials used by the artist along with the artists original vision and also to care for the future generations of students who will use the space in which the tile-work was inserted. Many tiles have been replaced by white tiles, tiles with a divergent colour pallet and technique, and in a few cases, the incorrect place or way around. These many factors make it increasingly difficult to maintain the artists original vision and destroy and chance of coherence within the artwork itself. The conservative technician cannot make new images to fill the empty spaces or mark the remaining images with their own creative input. with reliable photographic documentation that can provide us with the necessary vision to allow us to proceed with an accurate reconstruction, we have the obligation to proceed and return the piece of art to its true form, as in its current state, it is impossible to maintain its original glory. Using the information we have, we must find a way to differentiate the original tiles from the reconstructions in order to recreate and reclaim the original message from the artist. The objective of this project is to understand the significance of tiles in Vieira da Silva's art as well as the influence they had on the artist's pictorial language since the colour definition on tile work is vastly different from the painting process as the materials change during their merger. Another primary goal is to understand what the previous interventions achieved besides increasing the artworks durability. The main objective is to submit a proposal that can salvage the artist's visual intention and supports it for posteriority. In summary, this proposal goes further than the usual conservative interventions as it intends to recreate the original artistic worth, prioritising the aesthetics and keeping its soul alive.

Keywords: Vieira da Silva, tiles, conservation, restoration

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Authors: Melanie Francois, Gilles Caboche, Frederic Demoisson, Francois Maeght, Maria Paola Carpanese, Lionel Combemale, Pascal Briois

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Finding new clean, and efficient way for energy production is one of the actual global challenges. Advances in fuel cell technology have shown that, for few years, Protonic Ceramic Fuel Cell (PCFC) has attracted much attention in the field of new hydrogen energy thanks to their lower working temperature, possible higher efficiency, and better durability than classical SOFC. On the contrary of SOFC, where O²⁻ oxygen ion is the charge carrier, PCFC works with H⁺ proton as a charge carrier. Consequently, the lower activation energy of proton diffusion compared to the one of oxygen ion explains those benefits and allows PCFC to work in the 400-600°C temperature range. Doped-BaCeO₃ is currently the most chosen material for this application because of its high protonic conductivity; for example, BaCe₀.₉Y₀.₁O₃ δ exhibits a total conductivity of 1.5×10⁻² S.cm⁻¹ at 600°C in wet H₂. However, BaCeO₃ based perovskite has low stability in H₂O and/or CO₂ containing atmosphere, which limits their practical application. On the contrary, BaZrO₃ based perovskite exhibits good chemical stability but lower total conductivity than BaCeO₃ due to its larger grain boundary resistance. By substituting zirconium with 20% of yttrium, it is possible to achieve a total conductivity of 2.5×10⁻² S.cm⁻¹ at 600°C in wet H₂. However, the high refractory property of BaZr₀.₈Y₀.₂O₃-δ (noted BZY20) causes problems to obtain a dense membrane with large grains. Thereby, using a synthesis process that gives fine particles could allow better sinterability and thus decrease the number of grain boundaries leading to a higher total conductivity. In this work, BaZr₀.₈Y₀.₂O₃-δ have been synthesized by classical batch hydrothermal device and by a continuous hydrothermal device developed at ICB laboratory. The two variants of this process are able to work in supercritical conditions, leading to the formation of nanoparticles, which could be sintered at a lower temperature. The as-synthesized powder exhibits the right composition for the perovskite phase, impurities such as BaCO₃ and YO-OH were detected at very low concentration. Microstructural investigation and densification rate measurement showed that the addition of 1 wt% of ZnO as sintering aid and a sintering at 1550°C for 5 hours give high densified electrolyte material. Furthermore, it is necessary to heat the synthesized powder prior to the sintering to prevent the formation of secondary phases. It is assumed that this thermal treatment homogenizes the crystal structure of the powder and reduces the number of defects into the bulk grains. Electrochemical impedance spectroscopy investigations in various atmospheres and a large range of temperature (200-700°C) were then performed on sintered samples, and the protonic conductivity of BZY20 has been highlighted. Further experiments on half-cell, NiO-BZY20 as anode and BZY20 as electrolyte, are in progress.

Keywords: hydrothermal synthesis, impedance measurement, Y-doped BaZrO₃, proton conductor

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Authors: Amina Sa'id Muhammad, Asmau Ishaq Alhassan, Beba Raymond, Fatima Bello

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Severe acute malnutrition (SAM) remains a major killer of children under five years of age. Nigeria has the second highest burden of stunted children in the world, with a national prevalence rate of 32 percent of children under five. An estimated 2 million children in Nigeria suffer from severe acute malnutrition (SAM), and 3.9% of children in northwest Nigeria suffer from SAM, which is significantly higher than the national average of 2.1%. Community-Based Management of Acute Malnutrition (CMAM) has proven to be an effective intervention in the treatment of SAM in children using Ready-to-Use Therapeutic Food (RUTF). Ready-to-use therapeutic food (RUTF) is a key component for the treatment of Severe Acute Malnutrition. It contains all the energy and nutrients required for rapid catch-up growth and used particularly in the treatment of children over 6 months of age with SAM without medical complications. However, almost all RUTFs are currently imported to Nigeria from other countries. Shortages of RUTF due to logistics (shipping costs, delays, donor fatigue etc) and funding issues present a threat to the achievement of the 2030 World Health Assembly (WHA) targets for reducing malnutrition in addition to 2030 SDGs 2 (Zero Hunger), 3 (Good Health and Wellbeing), 12 (Responsible Consumption and Production), and 17 (Partnerships for the Goals), thus undermining its effectiveness in combating malnutrition On the other hand, the availability of human and material resources that will aid local production of RUTF presents an opportunity to fill in the gap in regular RUTF supply. About one thousand Nigerian children die of malnutrition-related causes every day, reaching a total of 361,000 each year. Owing to the high burden of malnutrition in Nigeria, the local production of RUTF is a logical step, that will ensure increased availability, acceptability, access, and efficiency in supply, and at lower costs. Objective(s): The objectives of this study were therefore, to formulate RUTF from locally available resources and to determine its energy and nutrients composition, incommensurate with the standard/commercial RUTF. Methods: Three samples of RUTF were formulated using locally available resources (soya beans, wheat, rice, baobab, brown-sugar, date palm and soya oil); which were subjected to various analysis to determine their energy/proximate composition, vitamin and mineral contents and organoleptic properties were also determined using sensory evaluation. Results: The energy values of the three samples of locally produced RUTF were found to be in conformity with WHO recommendation of ≥ 500 kcal per 100g. The energy values of the three RUTF samples produced in the current study were found to be 563.08, 503.67 and 528.98 kcal respectively. Sample A, B and C had protein content of 13.56% 16.71% and 14.62% respectively, which were higher than that of commercial RUTF (10.9%). Conclusions/recommendations: The locally formulated RUTF samples had energy value of more than 500 kcal per 100g; with an appreciable amount of macro and micro nutrients. The appearance, taste, flavor and general acceptability of the formulated RUTF samples were also commendable.

Keywords: energy, malnutrition, nutrients, RUTF

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Authors: Naiara Ozamiz Etcebarria, Sonia Ruiz De Azua Garcia, Agurtzane Ortiz Jauregi, Virginia Guillen Cañas

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Introduction: The most relevant competencies of a health professional are an adequate communication capacity, which will influence the satisfaction of professionals and patients, therapeutic compliance, conflict prevention, clinical outcomes´ improvement and efficiency of health services. The ability of Active listening , empathy, assertiveness and social skills, are important abilities to develop in all professions in which there is a relationship with other people. In the field of health, it is even more important to have adequate qualities so that the treatment with the patient will be adequate and satisfactory. We conducted a research with students of third year in the Degree of Medicine with the objectives: - to know how the active listening, empathy, assertiveness and social skills of students are. - to know if there are differences according to different demographic variables, such as sex, language, age, number of siblings and interest in the subject. Material and Methods: The students of the Third year in the Degree of Medicine (N = 212) participated voluntarily. Sociodemographic data were collected. Descriptive and comparative analysis of the averages of the students with respect to active listening, empathy, assertiveness and social skills were performed. Once the questionnaires were collected, they were entered into the SPSS 21 database. Four communicational aspects were evaluated: The active listening questionnaire, the TECA empathy questionnaire, the ACDA questionnaire and the EHS questionnaire Social Skills Scale. The active listening questionnaire assesses these factors: Listening without interruption and less contradiction, Listening with 100% attention, Listening beyond words, Listening encouraging the other to go deeper. The TECA questionnaire of cognitive and affective empathy evaluates: Adoption of perspectives, Emotional Comprehension, Emphasizing stress, Empathic joy. The EHS questionnaire Social Skills Scale: Self-expression in social situations, Defending one's own rights as a consumer, Expressing anger or dissatisfaction, Refusing to do and cutting interactions off, Making requests, Initiating positive interactions with the other sex. The ACDA questionnaire Assertiveness Assessment Scale evaluates self-assertiveness and heteroaservitivity. Applicability: To train these skills is so important for clinical practice of medical students and these capabilities that can be measured in a longitudinal way time. Ethical-legal aspects: The data were anonymous. The study was approved by the Ethics Committee. Results: The students of the Third year in the Degree of Medicine (34.4% Basque speakers and 65.6% Spanish speakers) with average age 20.93, (27.8% men and 72.2% women). There are no differences in social skills between men and women. The Basque speaker students of are more heteroactive (ACDA) than Spanish students. Active listening has a high correlation with social skills, especially with self-expression in social situations. Listening without interruption has a high correlation with self-expression in social situations and initiating positive interactions with the opposite sex. Adoption of perspectives presents a high correlation with auto- assertiveness. Emotional understanding presents a high correlation with positive interactions with the opposite sex. Empathic joy correlates with self-assertiveness, self-expression in social situations, and initiating positive interactions with the opposite sex.

Keywords: active listening, assertiveness, communicational skills, empathy, students of medicine

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Authors: Frea Van Steenweghen, Lander Hollevoet, Johan A. Martens

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Compared to other hydrogen (H₂) carriers, ammonia (NH₃) is one of the most promising carriers as it contains 17.6 wt% hydrogen. It is easily liquefied at ≈ 9–10 bar pressure at ambient temperature. More importantly, NH₃ is a carbon-free hydrogen carrier with no CO₂ emission at final decomposition. Ammonia has a well-defined regulatory framework and a good track record regarding safety concerns. Furthermore, the industry already has an existing transport infrastructure consisting of pipelines, tank trucks and shipping technology, as ammonia has been manufactured and distributed around the world for over a century. While NH₃ synthesis and transportation technological solutions are at hand, a missing link in the hydrogen delivery scheme from ammonia is an energy-lean and efficient technology for cracking ammonia into H₂ and N₂. The most explored option for ammonia decomposition is thermo-catalytic cracking which is, by itself, the most energy-efficient approach compared to other technologies, such as plasma and electrolysis, as it is the most energy-lean and robust option. The decomposition reaction is favoured only at high temperatures (> 300°C) and low pressures (1 bar) as the thermocatalytic ammonia cracking process is faced with thermodynamic limitations. At 350°C, the thermodynamic equilibrium at 1 bar pressure limits the conversion to 99%. Gaining additional conversion up to e.g. 99.9% necessitates heating to ca. 530°C. However, reaching thermodynamic equilibrium is infeasible as a sufficient driving force is needed, requiring even higher temperatures. Limiting the conversion below the equilibrium composition is a more economical option. Thermocatalytic ammonia cracking is documented in scientific literature. Among the investigated metal catalysts (Ru, Co, Ni, Fe, …), ruthenium is known to be most active for ammonia decomposition with an onset of cracking activity around 350°C. For establishing > 99% conversion reaction, temperatures close to 600°C are required. Such high temperatures are likely to reduce the round-trip efficiency but also the catalyst lifetime because of the sintering of the supported metal phase. In this research, the first focus was on catalyst bed design, avoiding diffusion limitation. Experiments in our packed bed tubular reactor set-up showed that extragranular diffusion limitations occur at low concentrations of NH₃ when reaching high conversion, a phenomenon often overlooked in experimental work. A second focus was thermocatalyst development for ammonia cracking, avoiding the use of noble metals. To this aim, candidate metals and mixtures were deposited on a range of supports. Sintering resistance at high temperatures and the basicity of the support were found to be crucial catalyst properties. The catalytic activity was promoted by adding alkaline and alkaline earth metals. A third focus was studying the optimum process configuration by process simulations. A trade-off between conversion and favorable operational conditions (i.e. low pressure and high temperature) may lead to different process configurations, each with its own pros and cons. For example, high-pressure cracking would eliminate the need for post-compression but is detrimental for the thermodynamic equilibrium, leading to an optimum in cracking pressure in terms of energy cost.

Keywords: ammonia cracking, catalyst research, kinetics, process simulation, thermodynamic equilibrium

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Authors: R. P. Hewawasam, M. H. A. D. de Silva, M. A. G. Iresha

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Obesity is associated with an increased risk of developing insulin resistance. Insulin resistance often progresses to type-2 diabetes mellitus and is linked to a wide variety of other pathophysiological features including hypertension, hyperlipidemia, atherosclerosis (metabolic syndrome) and polycystic ovarian syndrome. Macrosomia is common in infants born to not only women with gestational diabetes mellitus but also non-diabetic obese women. During the past two decades, obesity in children and adolescents has risen significantly in Asian populations including Sri Lanka. There is increasing evidence to believe that infants who are born large for gestational age (LGA) are more likely to be obese in childhood. It is also established from previous studies that Asian populations have higher percentage body fat at a lower body mass index compared to Caucasians. High leptin levels in cord blood have been reported to correlate with fetal adiposity at birth. Previous studies have also shown that cord blood C-peptide and insulin levels are significantly and positively correlated with birth weight. Therefore, the objective of this preliminary study was to determine the relationship between parameters of fetal insulin resistance such as leptin, C-peptide and insulin and the birth weight of the newborn in a study population in Southern Sri Lanka. Umbilical cord blood was collected from 90 newborns and the concentration of insulin, leptin, and C-peptide were measured by ELISA technique. Birth weight, length, occipital frontal, chest, hip and calf circumferences of newborns were measured and characteristics of the mother such as age, height, weight before pregnancy and weight gain were collected. The relationship between insulin, leptin, C-peptide, and anthropometrics were assessed by Pearson’s correlation while the Mann-Whitney U test was used to assess the differences in cord blood leptin, C-peptide, and insulin levels between groups. A significant difference (p < 0.001) was observed between the insulin levels of infants born LGA (18.73 ± 0.64 µlU/ml) and AGA (13.08 ± 0.43 µlU/ml). Consistently, A significant increase in concentration (p < 0.001) was observed in C-peptide levels of infants born LGA (9.32 ± 0.77 ng/ml) compared to AGA (5.44 ± 0.19 ng/ml). Cord blood leptin concentration of LGA infants (12.67 ng/mL ± 1.62) was significantly higher (p < 0.001) compared to the AGA infants (7.10 ng/mL ± 0.97). Significant positive correlations (p < 0.05) were observed among cord leptin levels and the birth weight, pre-pregnancy maternal weight and BMI between the infants of AGA and LGA. Consistently, a significant positive correlation (p < 0.05) was observed between the birth weight and the C peptide concentration. Significantly high concentrations of leptin, C-peptide and insulin levels in the cord blood of LGA infants suggest that they may be involved in regulating fetal growth. Although previous studies suggest comparatively high levels of body fat in the Asian population, values obtained in this study are not significantly different from values previously reported from Caucasian populations. According to this preliminary study, maternal pre-pregnancy BMI and weight may contribute as significant indicators of cord blood parameters of insulin resistance and possibly the birth weight of the newborn.

Keywords: large for gestational age, leptin, C-peptide, insulin

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Authors: Mindaugas Liaudanskas, Darius Kviklys, Kristina Zymonė, Raimondas Raudonis, Jonas Viškelis, Norbertas Uselis, Pranas Viškelis, Valdimaras Janulis

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Apples are among the most commonly consumed fruits in the world. Based on data from the year 2014, approximately 84.63 million tons of apples are grown per annum. Apples are widely used in food industry to produce various products and drinks (juice, wine, and cider); they are also used unprocessed. Apples in human diet are an important source of different groups of biological active compounds that can positively contribute to the prevention of various diseases. They are a source of various biologically active substances – especially vitamins, organic acids, micro- and macro-elements, pectins, and phenolic, triterpenic, and other compounds. Triterpenic compounds, which are characterized by versatile biological activity, are the biologically active compounds found in apples that are among the most promising and most significant for human health. A specific analytical procedure including sample preparation and High Performance Liquid Chromatography (HPLC) analysis was developed, optimized, and validated for the detection of triterpenic compounds in the samples of different apples, their peels, and flesh from widespread apple cultivars 'Aldas', 'Auksis', 'Connel Red', 'Ligol', 'Lodel', and 'Rajka' grown in Lithuanian climatic conditions. The conditions for triterpenic compound extraction were optimized: the solvent of the extraction was 100% (v/v) acetone, and the extraction was performed in an ultrasound bath for 10 min. Isocratic elution (the eluents ratio being 88% (solvent A) and 12% (solvent B)) for a rapid separation of triterpenic compounds was performed. The validation of the methodology was performed on the basis of the ICH recommendations. The following characteristics of validation were evaluated: the selectivity of the method (specificity), precision, the detection and quantitation limits of the analytes, and linearity. The obtained parameters values confirm suitability of methodology to perform analysis of triterpenic compounds. Using the optimised and validated HPLC technique, four triterpenic compounds were separated and identified, and their specificity was confirmed. These compounds were corosolic acid, betulinic acid, oleanolic acid, and ursolic acid. Ursolic acid was the dominant compound in all the tested apple samples. The detected amount of betulinic acid was the lowest of all the identified triterpenic compounds. The greatest amounts of triterpenic compounds were detected in whole apple and apple peel samples of the 'Lodel' cultivar, and thus apples and apple extracts of this cultivar are potentially valuable for use in medical practice, for the prevention of various diseases, for adjunct therapy, for the isolation of individual compounds with a specific biological effect, and for the development and production of dietary supplements and functional food enriched in biologically active compounds. Acknowledgements. This work was supported by a grant from the Research Council of Lithuania, project No. MIP-17-8.

Keywords: apples, HPLC, triterpenic compounds, validation

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Authors: Khondokar Farid Ahmmed, Robin Bown

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It is widely recognized that the formal financing of Small and Medium Size Enterprises (SMEs) by Private Commercial Banks (PCBs) is restricted. Due to changing financial market competition, SMEs are now important customers to PCBs in the member countries of the Asian Development Bank (ADB). Various initiatives in enhancing the efficiency of risk assessment of PCBs have failed in increasing financing accessibility in the traditional financing system where information asymmetry is a key constraint. In this circumstance, PCBs need to undertake a holistic approach. Holistic approach refers to methods that attempt to fundamentally change established traditions. To undertake holistic approach, this study intends to find the entire established financing culture between PCBs and SMEs in a new lens beyond the tradition on the basis of two basic questions: “What is the traditional lending culture between PCBs and SMEs” and “What could be potential role of PCBs to develop that culture where focusing on SME financing to PCBs". This study considered formal SME financing in Bangladesh by focusing on SMEs applying for their first loan. Bangladesh is a member country of ADB. The data collection method is semi-structured and we utilized face-to-face interviews with in-depth branch managers, higher officials and owner-managers of SME customers of PCBs and higher officials of SME Foundation and the Bangladesh central bank. Discourse analysis method was used for data analysis on the frame of thematic discussion fully based on participants’ views. The research found that branch managers and loan officers have a high level of power in assessing and financing decision-making. There is a changing attitude in PCB sector in requiring flexible collateral assets. Branch managers (Loan Officers) consider value of business prospect of owner-mangers as complementary of collateral assets. However, the study found the assessment process of business prospect is entirely unstructured and linked with socio-cultural settings that does not support PCBs’ changing manner in terms of collateral requirement. The study redefined and classified collateral assets to include all financing constructs in a structure. The degree of value of the collateral assets determines the degree of business prospects. This study suggested applying an outside classroom-learning paradigm such as “knowledge tour” to enhance the value of the kinds of collateral assets. This is the scope of PCBs in increasing SMEs’ financing eligibility in win-win basis. The findings and proposition could be effective in other ADB member countries and audiences in the field.

Keywords: CCA, financing, information asymmetry, PCA, PCB, financing

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Authors: Reem Alajmi, Hind Al Harbi, Tahany Ayaad, Zainab Al Musawi

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Hard ticks Hyalomma spp. (family: Ixodidae) are obligate ectoparasite in their all life stages on some domestic animals mainly camels and cattle. Ticks may lead to many economic and public health problems because of their blood feeding behavior. Also, they act as vectors for many bacterial, viral and protozoan agents which may cause serious diseases such as tick-born encephalitis, Rocky-mountain spotted fever, Q-fever and Lyme disease which can affect human and/or animals. In the present study, molecular identification of ticks that attack camels in Riyadh region, Saudi Arabia based on the partial sequence of mitochondrial 16s rRNA gene was applied. Also, the present study aims to detect natural infections of collected camel ticks with Rickessia spp. and Borelia spp. using PCR/hybridization of Citrate synthase encoding gene present in bacterial cells. Hard ticks infesting camels were collected from different camels located in a farm in Riyadh region, Saudi Arabia. Results of the present study showed that the collected specimens belong to two species: Hyalomma dromedari represent 99% of the identified specimens and Hyalomma marginatum which account for 1 % of identified ticks. The molecular identification was made through blasting the obtained sequence of this study with sequences already present and identified in GeneBank. All obtained sequences of H. dromedarii specimens showed 97-100% identity with the same gene sequence of the same species (Accession # L34306.1) which was used as a reference. Meanwhile, no intraspecific variations of H. marginatum mesured because only one specimen was collected. Results also had shown that the intraspecific variability between individuals of H. dromedarii obtained in 92 % of samples ranging from 0.2- 6.6%, while the remaining 7 % of the total samples of H. dromedarii showed about 10.3 % individual differences. However, the interspecific variability between H. dromedarii and H. marginatum was approximately 18.3 %. On the other hand, by using the technique of PCR/hybridization, we could detect natural infection of camel ticks with Rickettsia spp. and Borrelia spp. Results revealed the natural presence of both bacteria in collected ticks. Rickettsial spp. infection present in 29% of collected ticks, while 35% of collected specimen were infected with Borrelia spp. The valuable results obtained from the present study are a new record for the molecular identification of camel ticks in Riyadh, Saudi Arabia and their natural infection with both Rickettsia spp. and Borrelia spp. These results may help scientists to provide a good and direct control strategy of ticks in order to protect one of the most important economic animals which are camels. Also results of this project spotlight on the disease that might be transmitted by ticks to put out a direct protective plan to prevent spreading of these dangerous agents. Further molecular studies are needed to confirm the results of the present study by using other mitochondrial and nuclear genes for tick identification.

Keywords: Camel ticks, Rickessia spp. , Borelia spp. , mitochondrial 16s rRNA gene

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Authors: M. Pienaar, J. W. Odendaal, J. C. Smit, J. Joubert

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Simulations are commonly used to predict the bistatic radar cross section (RCS) of military targets since characterization measurements can be expensive and time consuming. It is thus important to accurately predict the bistatic RCS of targets. Computational electromagnetic (CEM) methods can be used for bistatic RCS prediction. CEM methods are divided into full-wave and asymptotic methods. Full-wave methods are numerical approximations to the exact solution of Maxwell’s equations. These methods are very accurate but are computationally very intensive and time consuming. Asymptotic techniques make simplifying assumptions in solving Maxwell's equations and are thus less accurate but require less computational resources and time. Asymptotic techniques can thus be very valuable for the prediction of bistatic RCS of electrically large targets, due to the decreased computational requirements. This study extends previous work by validating the accuracy of asymptotic techniques to predict bistatic RCS through comparison with full-wave simulations as well as measurements. Validation is done with canonical structures as well as complex realistic aircraft models instead of only looking at a complex slicy structure. The slicy structure is a combination of canonical structures, including cylinders, corner reflectors and cubes. Validation is done over large bistatic angles and at different polarizations. Bistatic RCS measurements were conducted in a compact range, at the University of Pretoria, South Africa. The measurements were performed at different polarizations from 2 GHz to 6 GHz. Fixed bistatic angles of β = 30.8°, 45° and 90° were used. The measurements were calibrated with an active calibration target. The EM simulation tool FEKO was used to generate simulated results. The full-wave multi-level fast multipole method (MLFMM) simulated results together with the measured data were used as reference for validation. The accuracy of physical optics (PO) and geometrical optics (GO) was investigated. Differences relating to amplitude, lobing structure and null positions were observed between the asymptotic, full-wave and measured data. PO and GO were more accurate at angles close to the specular scattering directions and the accuracy seemed to decrease as the bistatic angle increased. At large bistatic angles PO did not perform well due to the shadow regions not being treated appropriately. PO also did not perform well for canonical structures where multi-bounce was the main scattering mechanism. PO and GO do not account for diffraction but these inaccuracies tended to decrease as the electrical size of objects increased. It was evident that both asymptotic techniques do not properly account for bistatic structural shadowing. Specular scattering was calculated accurately even if targets did not meet the electrically large criteria. It was evident that the bistatic RCS prediction performance of PO and GO depends on incident angle, frequency, target shape and observation angle. The improved computational efficiency of the asymptotic solvers yields a major advantage over full-wave solvers and measurements; however, there is still much room for improvement of the accuracy of these asymptotic techniques.

Keywords: asymptotic techniques, bistatic RCS, geometrical optics, physical optics

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Authors: Naod Mekonnen Anega

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The very objective of this paper was to empirically identify technology tailored determinants to the adoption and adoption intensity (extent of use) of agricultural water management technologies in Meda Welabu Woreda, Oromia regional state, Ethiopia. Meda Welabu Woreda which is one of the administrative Woredas of the Oromia regional state was selected purposively as this Woreda is one of the Woredas in the region where small scale irrigation practices and the use of agricultural water management technologies can be found among smallholders. Using the existence water management practices (use of water management technologies) and land use pattern as a criterion Genale Mekchira Kebele is selected to undergo the study. A total of 200 smallholders were selected from the Kebele using the technique developed by Krejeie and Morgan. The study employed the Logit and Tobit models to estimate and identify the economic, social, geographical, household, institutional, psychological, technological factors that determine adoption and adoption intensity of water management technologies. The study revealed that while 55 of the sampled households are adopters of agricultural water management technology the rest 140 were non adopters of the technologies. Among the adopters included in the sample 97% are using river diversion technology (traditional) with traditional canal while the rest 7% percent are using pond with treadle pump technology. The Logit estimation reveled that while adoption of river diversion is positively and significantly affected by membership to local institutions, active labor force, income, access to credit and land ownership, adoption of treadle pump technology is positively and significantly affected by family size, education level, access to credit, extension contact, income, access to market, and slope. The Logit estimation also revealed that whereas, group action requirement, distance to farm, and size of active labor force negative and significantly influenced adoption of river diversion, age and perception has negatively and significantly influenced adoption decision of treadle pump technology. On the other hand, the Tobit estimation reveled that while adoption intensity (extent of use) of agricultural water management is positively and significantly affected by education, credit, and extension contact, access to credit, access to market and income. This study revealed that technology tailored study on adoption of Agricultural water management technologies (AWMTs) should be considered to indentify and scale up best agricultural water management practices. In fact, in countries like Ethiopia, where there is difference in social, economic, cultural, environmental and agro ecological conditions even within the same Kebele technology tailored study that fit the condition of each Kebele would help to identify and scale up best practices in agricultural water management.

Keywords: water management technology, adoption, adoption intensity, smallholders, technology tailored approach

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Authors: S. Raghibdoust, E. Kamari

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Research show that reduced functional hearing has a detrimental influence on the ability of an individual to establish proper phonological representations of words, since the phonological representations are claimed to mediate the conceptual processing of written words. Word processing efficiency is expected to decrease with a decrease in functional hearing. In other words, it is predicted that hearing individuals would be more capable of word processing than individuals with hearing loss, as their functional hearing works normally. Studies also demonstrate that the quality of the functional hearing affects reading comprehension via its effect on their word processing skills. In other words, better hearing facilitates the development of phonological knowledge, and can promote enhanced strategies for the recognition of written words, which in turn positively affect higher-order processes underlying reading comprehension. The aims of this study were to investigate and compare the effect of deafness on the participants’ abilities to process written words at the lexical and sentence levels through using two online and one offline reading comprehension tests. The performance of a group of 8 deaf male students (ages 8-12) was compared with that of a control group of normal hearing male students. All the participants had normal IQ and visual status, and came from an average socioeconomic background. None were diagnosed with a particular learning or motor disability. The language spoken in the homes of all participants was Persian. Two tests of word processing were developed and presented to the participants using OpenSesame software, in order to measure the speed and accuracy of their performance at the two perceptual and conceptual levels. In the third offline test of reading comprehension which comprised of semantically plausible and semantically implausible subject relative clauses, the participants had to select the correct answer out of two choices. The data derived from the statistical analysis using SPSS software indicated that hearing and deaf participants had a similar word processing performance both in terms of speed and accuracy of their responses. The results also showed that there was no significant difference between the performance of the deaf and hearing participants in comprehending semantically plausible sentences (p > 0/05). However, a significant difference between the performances of the two groups was observed with respect to their comprehension of semantically implausible sentences (p < 0/05). In sum, the findings revealed that the seriously impoverished sentence reading ability characterizing the profound deaf subjects of the present research, exhibited their reliance on reading strategies that are based on insufficient or deviant structural knowledge, in particular in processing semantically implausible sentences, rather than a failure to efficiently process written words at the lexical level. This conclusion, of course, does not mean to say that deaf individuals may never experience deficits at the word processing level, deficits that impede their understanding of written texts. However, as stated in previous researches, it sounds reasonable to assume that the more deaf individuals get familiar with written words, the better they can recognize them, despite having a profound phonological weakness.

Keywords: deafness, reading comprehension, reading strategy, word processing, subject and object relative sentences

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Authors: Getaneh Berie Tarekegn, Li-Chia Tai

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With the rapid advancement of artificial intelligence, low-power built-in sensors on Internet of Things devices, and communication technologies, location-aware services have become increasingly popular and have permeated every aspect of people’s lives. Global navigation satellite systems (GNSSs) are the default method of providing continuous positioning services for ground and aerial vehicles, as well as consumer devices (smartphones, watches, notepads, etc.). However, the environment affects satellite positioning systems, particularly indoors, in dense urban and suburban cities enclosed by skyscrapers, or when deep shadows obscure satellite signals. This is because (1) indoor environments are more complicated due to the presence of many objects surrounding them; (2) reflection within the building is highly dependent on the surrounding environment, including the positions of objects and human activity; and (3) satellite signals cannot be reached in an indoor environment, and GNSS doesn't have enough power to penetrate building walls. GPS is also highly power-hungry, which poses a severe challenge for battery-powered IoT devices. Due to these challenges, IoT applications are limited. Consequently, precise, seamless, and ubiquitous Positioning, Navigation and Timing (PNT) systems are crucial for many artificial intelligence Internet of Things (AI-IoT) applications in the era of smart cities. Their applications include traffic monitoring, emergency alarms, environmental monitoring, location-based advertising, intelligent transportation, and smart health care. This paper proposes a generative AI-based positioning scheme for large-scale wireless settings using fingerprinting techniques. In this article, we presented a semi-supervised deep convolutional generative adversarial network (S-DCGAN)-based radio map construction method for real-time device localization. We also employed a reliable signal fingerprint feature extraction method with t-distributed stochastic neighbor embedding (t-SNE), which extracts dominant features while eliminating noise from hybrid WLAN and long-term evolution (LTE) fingerprints. The proposed scheme reduced the workload of site surveying required to build the fingerprint database by up to 78.5% and significantly improved positioning accuracy. The results show that the average positioning error of GAILoc is less than 0.39 m, and more than 90% of the errors are less than 0.82 m. According to numerical results, SRCLoc improves positioning performance and reduces radio map construction costs significantly compared to traditional methods.

Keywords: location-aware services, feature extraction technique, generative adversarial network, long short-term memory, support vector machine

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Authors: Ishan Naidu, Jessica Ryvlin, Devin Videlefsky

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Introduction: Back pain is a leading cause of years lived with disability and economic burden, exceeding over $20 billion in healthcare costs not including indirect costs such as absence from work and caregiving. The multifactorial nature of back pain leads to treatment modalities administered by a variety of specialists, which are often disjointed. Multiple studies have found that patients receiving delayed physical therapy for lower back pain had higher medical-related costs from increased health service utilization as well as a reduced improvement in pain severity compared to early management. Uncoordinated health care delivery can exacerbate the physical and economic toll of the chronic condition, thus improvements in interdisciplinary, shared decision-making may improve outcomes. Objective: To assess whether a multidisciplinary spine clinic (MSC), consisting of orthopedic surgery, neurosurgery, pain medicine, and physiatry, alters interventional and non-interventional planning and treatment compared to a traditional unidisciplinary spine clinic (USC) including only orthopedic surgery. Methods: We conducted a retrospective cohort study with patients initially presenting for spine care to orthopedic surgeons between July 1, 2018 to June 30, 2019. Time to treatment recommendation, time to treatment and rates of treatment recommendations were assessed, including physical therapy, injections and surgery. Treatment rates were compared between MSC and USC using Pearson’s chi-square test logistic regression. Time to treatment recommendation and time to treatment were compared using log-rank test and Cox proportional hazard regression. All analyses were repeated for the propensity score (PS) matched subsample. Results: This study included 1,764 patients, with 692 at MSC and 1,072 at USC. Patients in MSC were more likely to be recommended injection when compared to USC (8.5% vs. 5.4%, p=0.01). When adjusted for confounders, the likelihood of injection recommendation remained greater in MSC than USC (Odds ratio [OR]=2.22, 95% CI: (1.39, 3.53), p=0.001). MSC was also associated with a shorter time to receiving injection recommendation versus USC (median: 21 vs. 32 days, log-rank: p<0.001; hazard ratio [HR]=1.90, 95% CI: (1.25, 2.90), p=0.003). MSC was associated with a higher likelihood of injection treatment (OR=2.27, 95% CI: (1.39, 3.73), p=0.001) and shorter lead time (HR=1.98, 95% CI: (1.27, 3.09), p=0.003). PS-matched analyses yielded similar conclusions. Conclusions: Care delivered at a multidisciplinary spine clinic was associated with a higher likelihood of recommending injection and a shorter lead time to injection administration when compared to a traditional unidisciplinary spine surgery clinic. Multidisciplinary clinics may facilitate coordinated care amongst different specialties resulting in increased utilization of less invasive treatment modalities while also improving care efficiency. The multidisciplinary clinic model is an important advancement in care delivery and communication, which can be used as a powerful method of improving patient outcomes as treatment guidelines evolve.

Keywords: coordinated care, epidural steroid injection, multi-disciplinary, non-invasive

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Authors: Taner Izzet Acarer, Ece Ceylan Baba

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This paper examines green building certification systems and their current processes in comparison with anticipatory systems. Rapid growth of human population and depletion of natural resources are causing irreparable damage to urban and natural environment. In this context, the concept of ‘sustainable architecture’ has emerged in the 20th century so as to establish and maintain standards for livable urban spaces, to improve quality of urban life, and to preserve natural resources for future generations. The construction industry is responsible for a large part of the resource consumption and it is believed that the ‘green building’ designs that emerge in construction industry can reduce environmental problems and contribute to sustainable development around the world. A building must meet a specific set of criteria, set forth through various certification systems, in order to be eligible for designation as a green building. It is disputable whether methods used by green building certification systems today truly serve the purposes of creating a sustainable world. Accordingly, this study will investigate the sets of rating systems used by the most popular green building certification programs, including LEED (Leadership in Energy and Environmental Design), BREEAM (Building Research Establishment's Environmental Assessment Methods), DGNB (Deutsche Gesellschaft für Nachhaltiges Bauen System), in terms of ‘Anticipatory Systems’ in accordance with the certification processes and their goals, while discussing their contribution to architecture. The basic methodology of the study is as follows. Firstly analyzes of brief historical and literature review of green buildings and certificate systems will be stated. Secondly, processes of green building certificate systems will be disputed by the help of anticipatory systems. Anticipatory Systems is a set of systems designed to generate action-oriented projections and to forecast potential side effects using the most current data. Anticipatory Systems pull the future into the present and take action based on future predictions. Although they do not have a claim to see into the future, they can provide foresight data. When shaping the foresight data, Anticipatory Systems use feedforward instead of feedback, enabling them to forecast the system’s behavior and potential side effects by establishing a correlation between the system’s present/past behavior and projected results. This study indicates the goals and current status of LEED, BREEAM and DGNB rating systems that created by using the feedback technique will be examined and presented in a chart. In addition, by examining these rating systems with the anticipatory system that using the feedforward method, the negative influences of the potential side effects on the purpose and current status of the rating systems will be shown in another chart. By comparing the two obtained data, the findings will be shown that rating systems are used for different goals than the purposes they are aiming for. In conclusion, the side effects of green building certification systems will be stated by using anticipatory system models.

Keywords: anticipatory systems, BREEAM, certificate systems, DGNB, green buildings, LEED

Procedia PDF Downloads 220

Authors: M. B. Atui, A. M. Silva, M. A. M. Marciano, M. I. Fioravanti, V. A. Franco, L. B. Chasin, A. R. Ferreira, M. D. Nogueira

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Fungi attack large amount of fruits and those who have suffered an injury on the surface are more susceptible to the growth, as they have pectinolytic enzymes that destroy the edible portion forming an amorphous and soft dough. The spores can reach the plant by the wind, rain and insects and fruit may have on its surface, besides the contaminants from the fruit trees, land and water, forming a flora composed mainly of yeasts and molds. Other contamination can occur for the equipment used to harvest, for the use of boxes and contaminated water to the fruit washing, for storage in dirty places. The hyphae in tomato products indicate the use of raw materials contaminated or unsuitable hygiene conditions during processing. Although fungi are inactivated in heat processing step, its hyphae remain in the final product and search for detection and quantification is an indicator of the quality of raw material. Howard Method count of fungi mycelia in industrialized pulps evaluates the amount of decayed fruits existing in raw material. The Brazilian legislation governing processed and packaged products set the limit of 40% of positive fields in tomato pulps. The aim of this study was to evaluate the quality of the tomato pulp sold in greater São Paulo, through a monitoring during the four seasons of the year. All over 2010, 110 samples have been examined; 21 were taking in spring, 31 in summer, 31 in fall and 27 in winter, all from different lots and trademarks. Samples have been picked up in several stores located in the city of São Paulo. Howard method was used, recommended by the AOAC, 19th ed, 2011 16:19:02 technique - method 965.41. Hundred percent of the samples contained fungi mycelia. The count average of fungi mycelia per season was 23%, 28%, 8,2% and 9,9% in spring, summer, fall and winter, respectively. Regarding the spring samples of the 21 samples analyzed, 14.3% were off-limits proposed by the legislation. As for the samples of the fall and winter, all were in accordance with the legislation and the average of mycelial filament count has not exceeded 20%, which can be explained by the low temperatures during this time of the year. The acquired samples in the summer and spring showed high percentage of fungal mycelium in the final product, related to the high temperatures in these seasons. Considering that the limit of 40% of positive fields is accepted for the Brazilian Legislation (RDC nº 14/2014), 3 spring samples (14%) and 6 summer samples (19%) will be over this limit and subject to law penalties. According to gathered data, 82% of manufacturers of this product manage to keep acceptable levels of fungi mycelia in their product. In conclusion, only 9.2% samples were for the limits established by Resolution RDC. 14/2014, showing that the limit of 40% is feasible and can be used by these segment industries. The result of the filament count mycelial by Howard method is an important tool in the microscopic analysis since it measures the quality of raw material used in the production of tomato products.

Keywords: fungi, howard, method, tomato, pulps

Procedia PDF Downloads 374

Authors: Hatem Abou-Senna, Essam Radwan

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With increasing traffic and limited resources, accommodating left-turning traffic has been a challenge for traffic engineers as they seek balance between intersection capacity and safety; these are two conflicting goals in the operation of a signalized intersection that are mitigated through signal phasing techniques. Hence, to increase the left-turn capacity and reduce the delay at the intersections, the Florida Department of Transportation (FDOT) moves forward with a vision of optimizing intersection control using innovative intersection designs through the Transportation Systems Management & Operations (TSM&O) program. These alternative designs successfully eliminate the left-turn phase, which otherwise reduces the conventional intersection’s (CI) efficiency considerably, and divide the intersection into smaller networks that would operate in a one-way fashion. This study focused on the Crossover Displaced Left-turn intersections (XDL), also known as Continuous Flow Intersections (CFI). The XDL concept is best suited for intersections with moderate to high overall traffic volumes, especially those with very high or unbalanced left turn volumes. There is little guidance on determining whether partial XDL intersections are adequate to mitigate the overall intersection condition or full XDL is always required. The primary objective of this paper was to evaluate the overall intersection performance in the case of different partial XDL designs compared to a full XDL. The XDL alternative was investigated for 4 different scenarios; partial XDL on the east-west approaches, partial XDL on the north-south approaches, partial XDL on the north and east approaches and full XDL on all 4 approaches. Also, the impact of increasing volume on the intersection performance was considered by modeling the unbalanced volumes with 10% increment resulting in 5 different traffic scenarios. The study intersection, located in Orlando Florida, is experiencing recurring congestion in the PM peak hour and is operating near capacity with volume to a capacity ratio closer to 1.00 due to the presence of two heavy conflicting movements; southbound and westbound. The results showed that a partial EN XDL alternative proved to be effective and compared favorably to a full XDL alternative followed by the partial EW XDL alternative. The analysis also showed that Full, EW and EN XDL alternatives outperformed the NS XDL and the CI alternatives with respect to the throughput, delay and queue lengths. Significant throughput improvements were remarkable at the higher volume level with percent increase in capacity of 25%. The percent reduction in delay for the critical movements in the XDL scenarios compared to the CI scenario ranged from 30-45%. Similarly, queue lengths showed percent reduction in the XDL scenarios ranging from 25-40%. The analysis revealed how partial XDL design can improve the overall intersection performance at various demands, reduce the costs associated with full XDL and proved to outperform the conventional intersection. However, partial XDL serving low volumes or only one of the critical movements while other critical movements are operating near or above capacity do not provide significant benefits when compared to the conventional intersection.

Keywords: continuous flow intersections, crossover displaced left-turn, microscopic traffic simulation, transportation system management and operations, VISSIM simulation model

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Authors: Marita Pigłowska, Beata Kurc, Maciej Galiński

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The application of carbon materials in the branches of the electrochemical industry shows an increasing tendency each year due to the many interesting properties they possess. These are, among others, a well-developed specific surface, porosity, high sorption capacity, good adsorption properties, low bulk density, electrical conductivity and chemical resistance. All these properties allow for their effective use, among others in supercapacitors, which can store electric charges of the order of 100 F due to carbon electrodes constituting the capacitor plates. Coals (including expanded graphite, carbon black, graphite carbon fibers, activated carbon) are commonly used in electrochemical methods of removing oil derivatives from water after tanker disasters, e.g. phenols and their derivatives by their electrochemical anodic oxidation. Phenol can occupy practically the entire surface of carbon material and leave the water clean of hydrophobic impurities. Regeneration of such electrodes is also not complicated, it is carried out by electrochemical methods consisting in unblocking the pores and reducing resistances, and thus their reactivation for subsequent adsorption processes. Graphite is commonly used as an anode material in lithium-ion cells, while due to the limited capacity it offers (372 mAh g-1), new solutions are sought that meet both capacitive, efficiency and economic criteria. Increasingly, biodegradable materials, green materials, biomass, waste (including agricultural waste) are used in order to reuse them and reduce greenhouse effects and, above all, to meet the biodegradability criterion necessary for the production of lithium-ion cells as chemical power sources. The most common of these materials are cellulose, starch, wheat, rice, and corn waste, e.g. from agricultural, paper and pharmaceutical production. Such products are subjected to appropriate treatments depending on the desired application (including chemical, thermal, electrochemical). Starch is a biodegradable polysaccharide that consists of polymeric units such as amylose and amylopectin that build an ordered (linear) and amorphous (branched) structure of the polymer. Carbon is also used as a catalyst. Elemental carbon has become available in many nano-structured forms representing the hybridization combinations found in the primary carbon allotropes, and the materials can be enriched with a large number of surface functional groups. There are many examples of catalytic applications of coal in the literature, but the development of this field has been hampered by the lack of a conceptual approach combining structure and function and a lack of understanding of material synthesis. In the context of catalytic applications, the integrity of carbon environmental management properties and parameters such as metal conductivity range and bond sequence management should be characterized. Such data, along with surface and textured information, can form the basis for the provision of network support services.

Keywords: carbon materials, catalysis, BET, capacitors, lithium ion cell

Procedia PDF Downloads 174

Authors: Andrea Pietrelli, Vincenzo Ferrara, Bruno Allard, Francois Buret, Irene Bavasso, Nicola Lovecchio, Francesca Costantini, Firas Khaled

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This paper aims to show some applications of microbial fuel cells (MFCs), an energy harvesting technique, as clean power source to supply low power device for application like wireless sensor network (WSN) for environmental monitoring. Furthermore, MFC can be used directly as biosensor to analyse parameters like pH and temperature or arranged in form of cluster devices in order to use as small power plant. An MFC is a bioreactor that converts energy stored in chemical bonds of organic matter into electrical energy, through a series of reactions catalysed by microorganisms. We have developed a lab-scale terrestrial microbial fuel cell (TMFC), based on soil that acts as source of bacteria and flow of nutrient and a lab-scale waste water microbial fuel cell (WWMFC), where waste water acts as flow of nutrient and bacteria. We performed large series of tests to exploit the capability as biosensor. The pH value has strong influence on the open circuit voltage (OCV) delivered from TMFCs. We analyzed three condition: test A and B were filled with same soil but changing pH from 6 to 6.63, test C was prepared using a different soil with a pH value of 6.3. Experimental results clearly show how with higher pH value a higher OCV was produced; indeed reactors are influenced by different values of pH which increases the voltage in case of a higher pH value until the best pH value of 7 is achieved. The influence of pH on OCV of lab-scales WWMFC was analyzed at pH value of 6.5, 7, 7.2, 7.5 and 8. WWMFCs are influenced from temperature more than TMFCs. We tested the power performance of WWMFCs considering four imposed values of ambient temperature. Results show how power performance increase proportionally with higher temperature values, doubling the output power from 20° to 40°. The best value of power produced from our lab-scale TMFC was equal to 310 μW using peaty soil, at 1KΩ, corresponding to a current of 0.5 mA. A TMFC can supply proper energy to low power devices of a WSN by means of the design of three stages scheme of an energy management system, which adapts voltage level of TMFC to those required by a WSN node, as 3.3V. Using a commercial DC/DC boost converter, that needs an input voltage of 700 mV, the current source of 0.5 mA, charges a capacitor of 6.8 mF until it will have accumulated an amount of charge equal to 700 mV in a time of 10 s. The output stage includes an output switch that close the circuit after a time of 10s + 1.5ms because the converter can boost the voltage from 0.7V to 3.3V in 1.5 ms. Furthermore, we tested in form of clusters connected in series up to 20 WWMFCs, we have obtained a high voltage value as output, around 10V, but low current value. MFC can be considered a suitable clean energy source to be used to supply low power devices as a WSN node or to be used directly as biosensor.

Keywords: energy harvesting, low power electronics, microbial fuel cell, terrestrial microbial fuel cell, waste-water microbial fuel cell, wireless sensor network

Procedia PDF Downloads 207

Authors: M. Hosseini, N. Ghorbani Amirabad, M. Zhian

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Seismic design codes accept structural and nonstructural damages after the sever earthquakes (provided that the building is prevented from collapse), so that in many cases demolishing and reconstruction of the building is inevitable, and this is usually very difficult, costly and time consuming. Therefore, designing and constructing of buildings in such a way that they can be easily repaired after earthquakes, even major ones, is quite desired. For this purpose giving the possibility of rocking or see-saw motion to the building structure, partially or as a whole, has been used by some researchers in recent decade .the central support which has a main role in creating the possibility of see-saw motion in the building’s structural system. In this paper, paying more attention to the key role of the central fuse and support, an innovative energy dissipater which can act as the central fuse and support of the building with seesaw motion is introduced, and the process of reaching an optimal geometry for that by using finite element analysis is presented. Several geometric shapes were considered for the proposed central fuse and support. In each case the hysteresis moment rotation behavior of the considered fuse were obtained under simultaneous effect of vertical and horizontal loads, by nonlinear finite element analyses. To find the optimal geometric shape, the maximum plastic strain value in the fuse body was considered as the main parameter. The rotational stiffness of the fuse under the effect of acting moments is another important parameter for finding the optimum shape. The proposed fuse and support can be called Yielding Curved Bars and Clipped Hemisphere Core (YCB&CHC or more briefly YCB) energy dissipater. Based on extensive nonlinear finite element analyses it was found out the using rectangular section for the curved bars gives more reliable results. Then, the YCB energy dissipater with the optimal shape was used in a structural model of a 12 story regular building as its central fuse and support to give it the possibility of seesaw motion, and its seismic responses were compared to those of a the building in the fixed based conditions, subjected to three-components acceleration of several selected earthquakes including Loma Prieta, Northridge, and Park Field. In building with see-saw motion some simple yielding-plate energy dissipaters were also used under circumferential columns.The results indicated that equipping the buildings with central and circumferential fuses result in remarkable reduction of seismic responses of the building, including the base shear, inter story drift, and roof acceleration. In fact by using the proposed technique the plastic deformations are concentrated in the fuses in the lowest story of the building, so that the main body of the building structure remains basically elastic, and therefore, the building can be easily repaired after earthquake.

Keywords: rocking mechanism, see-saw motion, finite element analysis, hysteretic behavior

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Authors: Martin Arguelles Perez, Woosoon Yim, Alexander Barzilov

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High-fidelity radiation monitoring is an essential component in the enhancement of the situational awareness capabilities of the Department of Energy’s Office of Environmental Management (DOE-EM) personnel. In this paper, multiple units of unmanned aerial vehicles (UAVs) each equipped with a cadmium zinc telluride (CZT) gamma-ray sensor are used for radiation source localization, which can provide vital real-time data for the EM tasks. To achieve this goal, a fully autonomous system of multicopter-based UAV swarm in 3D tetrahedron formation is used for surveying the area of interest and performing radiation source localization. The CZT sensor used in this study is suitable for small-size multicopter UAVs due to its small size and ease of interfacing with the UAV’s onboard electronics for high-resolution gamma spectroscopy enabling the characterization of radiation hazards. The multicopter platform with a fully autonomous flight feature is suitable for low-altitude applications such as radiation contamination sites. The conventional approach uses a single UAV mapping in a predefined waypoint path to predict the relative location and strength of the source, which can be time-consuming for radiation localization tasks. The proposed UAV swarm-based approach can significantly improve its ability to search for and track radiation sources. In this paper, two approaches are developed using (a) 2D planar circular (3 UAVs) and (b) 3D tetrahedron formation (4 UAVs). In both approaches, accurate estimation of the gradient vector is crucial for heading angle calculation. Each UAV carries the CZT sensor; the real-time radiation data are used for the calculation of a bulk heading vector for the swarm to achieve a UAV swarm’s source-seeking behavior. Also, a spinning formation is studied for both cases to improve gradient estimation near a radiation source. In the 3D tetrahedron formation, a UAV located closest to the source is designated as a lead unit to maintain the tetrahedron formation in space. Such a formation demonstrated a collective and coordinated movement for estimating a gradient vector for the radiation source and determining an optimal heading direction of the swarm. The proposed radiation localization technique is studied by computer simulation and validated experimentally in the indoor flight testbed using gamma sources. The technology presented in this paper provides the capability to readily add/replace radiation sensors to the UAV platforms in the field conditions enabling extensive condition measurement and greatly improving situational awareness and event management. Furthermore, the proposed radiation localization approach allows long-term measurements to be efficiently performed at wide areas of interest to prevent disasters and reduce dose risks to people and infrastructure.

Keywords: radiation, unmanned aerial system(UAV), source localization, UAV swarm, tetrahedron formation

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Authors: E. K. Mendez, N. A. Salazar, C. E. Orrego

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There is undoubted proof that increasing the intake of fruit lessens the risk of hypertension, coronary heart disease, stroke, and probable evidence that lowers the risk of cancer. Proper fruit drying is an excellent alternative to make their shelf-life longer, commercialization easier, and ready-to-eat healthy products or ingredients. The conventional way of drying is by hot air forced convection. However, this process step often requires a very long residence time; furthermore, it is highly energy consuming and detrimental to the product quality. Nowadays, power ultrasound (US) technic has been considered as an emerging and promising technology for industrial food processing. Most of published works dealing with drying food assisted by US have studied the effect of ultrasonic pre-treatment prior to air-drying on food and the airborne US conditions during dehydration. In this work a new approach was tested taking in to account drying time and two quality parameters of mango slices dehydrated by convection assisted by 20 KHz power US applied directly using a holed plate as product support and sound transmitting surface. During the drying of mango (Mangifera indica L.) slices (ca. 6.5 g, 0.006 m height and 0.040 m diameter), their weight was recorded every hour until final moisture content (10.0±1.0 % wet basis) was reached. After previous tests, optimization of three drying parameters - frequencies (2, 5 and 8 minutes each half-hour), air temperature (50-55-60⁰C) and power (45-70-95W)- was attempted by using a Box–Behnken design under the response surface methodology for the optimal drying time, color parameters and rehydration rate of dried samples. Assays involved 17 experiments, including a quintuplicate of the central point. Dried samples with and without US application were packed in individual high barrier plastic bags under vacuum, and then stored in the dark at 8⁰C until their analysis. All drying assays and sample analysis were performed in triplicate. US drying experimental data were fitted with nine models, among which the Verna model resulted in the best fit with R2 > 0.9999 and reduced χ2 ≤ 0.000001. Significant reductions in drying time were observed for the assays that used lower frequency and high US power. At 55⁰C, 95 watts and 2 min/30 min of sonication, 10% moisture content was reached in 211 min, as compared with 320 min for the same test without the use of US (blank). Rehydration rates (RR), defined as the ratio of rehydrated sample weight to that of dry sample and measured, was also larger than those of blanks and, in general, the higher the US power, the greater the RR. The direct contact and intermittent US treatment of mango slices used in this work improve drying rates and dried fruit rehydration ability. This technique can thus be used to reduce energy processing costs and the greenhouse gas emissions of fruit dehydration.

Keywords: ultrasonic assisted drying, fruit drying, mango slices, contact ultrasonic drying

Procedia PDF Downloads 345

Authors: Hsin-Hung Lin, Janet Chang, Te-Yi Chang, You-Sheng Huang

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The natural and men-made disasters have become huge challenges for tourism destinations as well as emphasizing the fragility of the industry. Hot springs, among all destinations, are prone to disasters due to their dependence on natural resources and locations. After the COVID-19 outbreak, hot spring destinations have experienced not only the loss of businesses but also the psychological trauma. However, evidence has also shown that the impacts may not necessarily reduce the resilience for people but may be converted into posttraumatic growth. In Taiwan, a large proportion of hot springs are located in rural or indigenous areas. As a result, hot spring resources are associated with community cohesion for local residents. Yet prior research on hot spring destinations has mainly focused on visitors, whereas residents have been overlooked. More specifically, the relationship between hot springs resources and resident resilience in the face of the COVID-19 impacts remains unclear. To fulfill this knowledge gap, this paper aims to explore the COVID-19 impacts on residents’ hot spring experiences as well as individual and community resilience from the perspective of posttraumatic growth. A total of 315 residents of 13 hot spring destinations that are most popular in Taiwan were recruited. Online questionnaires were distributed over travel forums and social networks after the COVID-19. This paper subsequently used Partial Least Squares Structural Equation Modeling for data analysis as the technique offers significant advantages in addressing nonnormal data and small sample sizes. A preliminary test was conducted, and the results showed acceptable internal consistency and no serious common method variance. The path analysis demonstrated that the COVID-19 impacts strengthened residents’ perceptions of hot spring resources and experiences, implying that the pandemic had propelled the residents to visit hot springs for the healing benefits. In addition, the COVID-19 impacts significantly enhanced residents’ individual and community resilience, which indicates that the residents at hot springs are more resilient thanks to their awareness of external risks. Thirdly, residents’ individual resilience was positively associated with hot spring experiences, while community resilience was not affected by hot spring experiences. Such findings may suggest that hot spring experiences are more related to individual-level experiences and, consequently, have insignificant influence on community resilience. Finally, individual resilience was proved to be the most relevant factor that help foster community resilience. To conclude, the authorities may consider exploiting the hot spring resources so as to increase individual resilience for local residents. Such implications can be used as a reference for other post-disaster tourist destinations as well. As for future research, longitudinal studies with qualitative methods are suggested to better understand how the hot spring experiences have changed individuals and communities over the long term. It should be noted that the main subjects of this paper were focused on the hot spring communities in Taiwan. Therefore, the results cannot be generalized for all types of tourism destinations. That is, more diverse tourism destinations may be investigated to provide a broader perspective of post-disaster recovery.

Keywords: community resilience, hot spring destinations, individual resilience, posttraumatic growth

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Authors: Szymon Kuczynski, Krystian Liszka, Mariusz Laciak, Andrii Oliinyk, Adam Szurlej

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Currently, in automotive transport to power vehicles, almost exclusively hydrocarbon based fuels are used. Due to increase of hydrocarbon fuels consumption, quality parameters are tightend for clean environment. At the same time efforts are undertaken for development of alternative fuels. The reasons why looking for alternative fuels for petroleum and diesel are: to increase vehicle efficiency and to reduce the environmental impact, reduction of greenhouse gases emissions and savings in consumption of limited oil resources. Significant progress was performed on development of alternative fuels such as methanol, ethanol, natural gas (CNG / LNG), LPG, dimethyl ether (DME) and biodiesel. In addition, biggest vehicle manufacturers work on fuel cell vehicles and its introduction to the market. Alcohols such as methanol and ethanol create the perfect fuel for spark-ignition engines. Their advantages are high-value antiknock which determines their application as additive (10%) to unleaded petrol and relative purity of produced exhaust gasses. Ethanol is produced in distillation process of plant products, which value as a food can be irrational. Ethanol production can be costly also for the entire economy of the country, because it requires a large complex distillation plants, large amounts of biomass and finally a significant amount of fuel to sustain the process. At the same time, the fermentation process of plants releases into the atmosphere large quantities of carbon dioxide. Natural gas cannot be directly converted into liquid fuels, although such arrangements have been proposed in the literature. Going through stage of intermediates is inevitable yet. Most popular one is conversion to methanol, which can be processed further to dimethyl ether (DME) or olefin (ethylene and propylene) for the petrochemical sector. Methanol uses natural gas as a raw material, however, requires expensive and advanced production processes. In relation to pollution emissions, the optimal vehicle fuel is LPG which is used in many countries as an engine fuel. Production of LPG is inextricably linked with production and processing of oil and gas, and which represents a small percentage. Its potential as an alternative for traditional fuels is therefore proportionately reduced. Excellent engine fuel may be biogas, however, follows to the same limitations as ethanol - the same production process is used and raw materials. Most essential fuel in the campaign of environment protection against pollution is natural gas. Natural gas as fuel may be either compressed (CNG) or liquefied (LNG). Natural gas can also be used for hydrogen production in steam reforming. Hydrogen can be used as a basic starting material for the chemical industry, an important raw material in the refinery processes, as well as a fuel vehicle transportation. Natural gas can be used as CNG which represents an excellent compromise between the availability of the technology that is proven and relatively cheap to use in many areas of the automotive industry. Natural gas can also be seen as an important bridge to other alternative sources of energy derived from fuel and harmless to the environment. For these reasons CNG as a fuel stimulates considerable interest in the worldwide.

Keywords: alternative fuels, CNG (Compressed Natural Gas), LNG (Liquefied Natural Gas), NGVs (Natural Gas Vehicles)

Procedia PDF Downloads 181

Authors: Basiru Amuneni

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Astronomy is one domain with a rise in data. Traditional tools for data management have been employed in the quest for knowledge discovery. However, these traditional tools become limited in the face of big. One means of maximizing knowledge discovery for big data is the use of scientific visualisation. The aim of the work is to explore the possibilities offered by emerging creative technologies of Virtual Reality (VR) systems and game engines to visualize multiwavelength datasets. Game Engines are primarily used for developing video games, however their advanced graphics could be exploited for scientific visualization which provides a means to graphically illustrate scientific data to ease human comprehension. Modern astronomy is now in the era of multiwavelength data where a single galaxy for example, is captured by the telescope several times and at different electromagnetic wavelength to have a more comprehensive picture of the physical characteristics of the galaxy. Visualising this in an immersive environment would be more intuitive and natural for an observer. This work presents a standalone VR application that accesses galaxy FITS files. The application was built using the Unity Game Engine for the graphics underpinning and the OpenXR API for the VR infrastructure. The work used a methodology known as Design Science Research (DSR) which entails the act of ‘using design as a research method or technique’. The key stages of the galaxy modelling pipeline are FITS data preparation, Galaxy Modelling, Unity 3D Visualisation and VR Display. The FITS data format cannot be read by the Unity Game Engine directly. A DLL (CSHARPFITS) which provides a native support for reading and writing FITS files was used. The Galaxy modeller uses an approach that integrates cleaned FITS image pixels into the graphics pipeline of the Unity3d game Engine. The cleaned FITS images are then input to the galaxy modeller pipeline phase, which has a pre-processing script that extracts, pixel, galaxy world position, and colour maps the FITS image pixels. The user can visualise image galaxies in different light bands, control the blend of the image with similar images from different sources or fuse images for a holistic view. The framework will allow users to build tools to realise complex workflows for public outreach and possibly scientific work with increased scalability, near real time interactivity with ease of access. The application is presented in an immersive environment and can use all commercially available headset built on the OpenXR API. The user can select galaxies in the scene, teleport to the galaxy, pan, zoom in/out, and change colour gradients of the galaxy. The findings and design lessons learnt in the implementation of different use cases will contribute to the development and design of game-based visualisation tools in immersive environment by enabling informed decisions to be made.

Keywords: astronomy, visualisation, multiwavelenght dataset, virtual reality

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Authors: Hsin-Hung Lin, Janet Chang, Te-Yi Chang, You-Sheng Huang

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The natural and men-made disasters have become huge challenges for tourism destinations as well as emphasizing the fragility of the industry. Hot springs, among all destinations, are prone to disasters due to their dependence on natural resources and locations. After the COVID-19 outbreak, hot spring destinations have experienced not only the loss of businesses but also the psychological trauma. However, evidence has also shown that the impacts may not necessarily reduce the resilience for people but may be converted into posttraumatic growth. In Taiwan, a large proportion of hot springs are located in rural or indigenous areas. As a result, hot spring resources are associated with community cohesion for local residents. Yet prior research on hot spring destinations has mainly focused on visitors, whereas residents have been overlooked. More specifically, the relationship between hot springs resources and resident resilience in the face of the COVID-19 impacts remains unclear. To fulfill this knowledge gap, this paper aims to explore the COVID-19 impacts on residents’ hot spring experiences as well as individual and community resilience from the perspective of posttraumatic growth. A total of 315 residents of 13 hot spring destinations that are most popular in Taiwan were recruited. Online questionnaires were distributed over travel forums and social networks after the COVID-19. This paper subsequently used Partial Least Squares Structural Equation Modeling for data analysis as the technique offers significant advantages in addressing nonnormal data and small sample sizes. A preliminary test was conducted, and the results showed acceptable internal consistency and no serious common method variance. The path analysis demonstrated that the COVID-19 impacts strengthened residents’ perceptions of hot spring resources and experiences, implying that the pandemic had propelled the residents to visit hot springs for the healing benefits. In addition, the COVID-19 impacts significantly enhanced residents’ individual and community resilience, which indicates that the residents at hot springs are more resilient thanks to their awareness of external risks. Thirdly, residents’ individual resilience was positively associated with hot spring experiences, while community resilience was not affected by hot spring experiences. Such findings may suggest that hot spring experiences are more related to individual-level experiences and, consequently, have insignificant influence on community resilience. Finally, individual resilience was proved to be the most relevant factor that help foster community resilience. To conclude, the authorities may consider exploiting the hot spring resources so as to increase individual resilience for local residents. Such implications can be used as a reference for other post-disaster tourist destinations as well.As for future research, longitudinal studies with qualitative methods are suggested to better understand how the hot spring experiences have changed individuals and communities over the long term. It should be noted that the main subjects of this paper were focused on the hot spring communities in Taiwan. Therefore, the results cannot be generalized for all types of tourism destinations. That is, more diverse tourism destinations may be investigated to provide a broader perspective of post-disaster recovery.

Keywords: community resilience, hot spring destinations, individual resilience, posttraumatic growth (PTG)

Procedia PDF Downloads 74

Authors: Jovana Grahovac, Ivana Pajcin, Natasa Lukic, Jelena Dodic, Aleksandar Jokic

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To obtain purified biomass to be used in the plant pathogen biocontrol or as soil biofertilizer, it is necessary to eliminate residual broth components at the end of the fermentation process. The main drawback of membrane separation techniques is permeate flux decline due to the membrane fouling. Fouling mitigation measures increase the pressure drop along membrane channel due to the increased resistance to flow of the feed suspension, thus increasing the hydraulic power drop. At the same time, these measures lead to an increase in the permeate flux due to the reduced resistance of the filtration cake on the membrane surface. Because of these opposing effects, the energy efficiency of fouling mitigation measures is limited, and the justification of its application is provided by information on a reducing specific energy consumption compared to a case without any measures employed. In this study, the influence of static mixer (Kenics) and air-sparging (two-phase flow) on reduction of specific energy consumption (ER) was investigated. Cultivation Bacillus velezensis was carried out in the 3-L bioreactor (Biostat® Aplus) containing 2 L working volume with two parallel Rushton turbines and without internal baffles. Cultivation was carried out at 28 °C on at 150 rpm with an aeration rate of 0.75 vvm during 96 h. The experiments were carried out in a conventional cross-flow microfiltration unit. During experiments, permeate and retentate were recycled back to the broth vessel to simulate continuous process. The single channel ceramic membrane (TAMI Deutschland) used had a nominal pore size 200 nm with the length of 250 mm and an inner/external diameter of 6/10 mm. The useful membrane channel surface was 4.33×10⁻³ m². Air sparging was brought by the pressurized air connected by a three-way valve to the feed tube by a simple T-connector without diffusor. The different approaches to flux improvement are compared in terms of energy consumption. Reduction of specific energy consumption compared to microfiltration without fouling mitigation is around 49% and 63%, for use of two-phase flow and a static mixer, respectively. In the case of a combination of these two fouling mitigation methods, ER is 60%, i.e., slightly lower compared to the use of turbulence promoter alone. The reason for this result can be found in the fact that flux increase is more affected by the presence of a Kenics static mixer while sparging results in an increase of energy used during microfiltration. By comparing combined method with turbulence promoter flux enhancement method ER is negative (-7%) which can be explained by increased power consumption for air flow with moderate contribution to the flux increase. Another confirmation for this fact can be found by comparing energy consumption values for combined method with energy consumption in the case of two-phase flow. In this instance energy reduction (ER) is 22% that demonstrates that turbulence promoter is more efficient compared to two phase flow. Antimicrobial activity of Bacillus velezensis biomass against phytopathogenic isolates Xanthomonas campestris was preserved under different fouling reduction methods.

Keywords: Bacillus velezensis, microfiltration, static mixer, two-phase flow

Procedia PDF Downloads 118

Authors: Maria Kountouridou, Dino Domic

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Within an increasingly competitive and dynamic environment, the higher education sector is becoming more commodified, with the concept of branding to become exceedingly imperative and an inextricable ingredient for the university’s success. Branding in higher education has proven to be an effective strategy that managed to receive considerable attention in the recent few years, and a growing number of articles have begun to appear in the literature. However, a clear void in the literature confirms that the concept of students’ perceptions towards the university’s brand image has not been researched extensively. An investigation on this central concept is of paramount importance since it will facilitate the development of an inductively generated theoretical model concerning branding in higher education. This research focuses on examining the impact of the ‘positive-visualization-course in brand identity’ upon the perception of freshmen students towards a university’s brand image. A grounded theory methodology has been selected, consisting of semi-structured interviews. Forty-two students have participated in the research, among which twenty-five women and seventeen men. The identification of the sample emerged through the use of the snowball sampling technique. The participants were divided into two groups (experimental and control group) after the researcher had taken into consideration the factor ‘program of study’, to eliminate any possible interaction between the participants of each group. An experiment was carried out where a ‘positive-visualization-course in brand identity’ was conducted among the participants of the experimental group, while the participants of the control group have not been exposed to the course. For the purpose of this research, the term ‘positive-visualization-course in brand identity’ refers to a course where brand history, past achievements/recognitions/awards, its values, and its mission are presented. Prior to the course implementation, face-to-face semi-structured interviews were carried out among the participants of both groups, with the aim of examining the freshmen students’ perceptions towards the university’s brand image. One week after the course implementation, the researcher carried out semi-structured interviews with the participants of the experimental group only in order to identify whether students’ perceptions had been affected after the course completion. Four months after the course completion, semi-structured interviews were carried out among the participants of both groups. Eight months after the course completion, semi-structured interviews were conducted with the aim of identifying the freshmen students’ updated perceptions. Data has been analyzed using substantive coding (open and selective coding), theoretical coding, field memos, and constant comparative analysis. The findings strongly suggest that the ‘positive-visualization-course in brand identity’ can positively affect freshmen students’ perceptions towards a university’s brand image. Additionally, other factors conduce to the formation of perception throughout the months. This study contributes and expands upon the existing literature by presenting an inductively generated theoretical model to guide future research in the links between ‘positive-visualization-course in brand identity’ and the perception of freshmen students towards a university’s brand image.

Keywords: brand image, brand name, branding, higher education marketing, perception

Procedia PDF Downloads 178

Authors: Andrea Ghermandi

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Natural treatment systems such as constructed wetlands and waste stabilization ponds are increasingly used to treat water and wastewater from a variety of sources, including stormwater and polluted surface water. The provision of ancillary benefits in the form of cultural ecosystem services makes these systems unique among water and wastewater treatment technologies and greatly contributes to determine their potential role in promoting sustainable water management practices. A quantitative analysis of these benefits, however, has been lacking in the literature. Here, a critical assessment of the recreational and educational benefits in natural treatment systems is provided, which combines observed public use from a survey of managers and operators with estimated public use as obtained using geotagged photos from social media as a proxy for visitation rates. Geographic Information Systems (GIS) are used to characterize the spatial boundaries of 273 natural treatment systems worldwide. Such boundaries are used as input for the Application Program Interfaces (APIs) of two popular photo-sharing websites (Flickr and Panoramio) in order to derive the number of photo-user-days, i.e., the number of yearly visits by individual photo users in each site. The adequateness and predictive power of four univariate calibration models using the crowdsourced data as a proxy for visitation are evaluated. A high correlation is found between photo-user-days and observed annual visitors (Pearson's r = 0.811; p-value < 0.001; N = 62). Standardized Major Axis (SMA) regression is found to outperform Ordinary Least Squares regression and count data models in terms of predictive power insofar as standard verification statistics – such as the root mean square error of prediction (RMSEP), the mean absolute error of prediction (MAEP), the reduction of error (RE), and the coefficient of efficiency (CE) – are concerned. The SMA regression model is used to estimate the intensity of public use in all 273 natural treatment systems. System type, influent water quality, and area are found to statistically affect public use, consistently with a priori expectations. Publicly available information regarding the home location of the sampled visitors is derived from their social media profiles and used to infer the distance they are willing to travel to visit the natural treatment systems in the database. Such information is analyzed using the travel cost method to derive monetary estimates of the recreational benefits of the investigated natural treatment systems. Overall, the findings confirm the opportunities arising from an integrated design and management of natural treatment systems, which combines the objectives of water quality enhancement and provision of cultural ecosystem services through public use in a multi-functional approach and compatibly with the need to protect public health.

Keywords: constructed wetlands, cultural ecosystem services, ecological engineering, waste stabilization ponds

Procedia PDF Downloads 180

Authors: A. Volperts, G. Dobele, A. Zhurinsh, I. Kruusenberg, A. Plavniece, J. Locs

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Nowadays energy consumption constantly increases and development of effective and cheap electrochemical sources of power, such as fuel cells and electrochemical capacitors, is topical. Due to their high specific power, charge and discharge rates, working lifetime supercapacitor based energy accumulation systems are more and more extensively being used in mobile and stationary devices. Lignocellulosic materials are widely used as precursors and account for around 45% of the total raw materials used for the manufacture of activated carbon which is the most suitable material for supercapacitors. First part of our research is devoted to study of influence of main stages of wood thermochemical activation parameters on activated carbons porous structure formation. It was found that the main factors governing the properties of carbon materials are specific surface area, volume and pore size distribution, particles dispersity, ash content and oxygen containing groups content. Influence of activated carbons attributes on capacitance and working properties of supercapacitor are demonstrated. The correlation between activated carbons porous structure indices and electrochemical specifications of supercapacitors with electrodes made from these materials has been determined. It is shown that if synthesized activated carbons are used in supercapacitors then high specific capacitances can be reached – more than 380 F/g in 4.9M sulfuric acid based electrolytes and more than 170 F/g in 1 M tetraethylammonium tetrafluoroborate in acetonitrile electrolyte. Power specifications and minimal price of H₂-O₂ fuel cells are limited by the expensive platinum-based catalysts. The main direction in development of non-platinum catalysts for the oxygen reduction is the study of cheap porous carbonaceous materials which can be obtained by the pyrolysis of polymers including renewable biomass. It is known that nitrogen atoms in carbon materials to a high degree determine properties of the doped activated carbons, such as high electrochemical stability, hardness, electric resistance, etc. The lack of sufficient knowledge on the doping of the carbon materials calls for the ongoing researches of properties and structure of modified carbon matrix. In the second part of this study, highly porous activated carbons were synthesized using alkali thermochemical activation from wood, cellulose and cellulose production residues – craft lignin and sewage sludge. Activated carbon samples were doped with dicyandiamide and melamine for the application as fuel cell cathodes. Conditions of nitrogen introduction (solvent, treatment temperature) and its content in the carbonaceous material, as well as porous structure characteristics, such as specific surface and pore size distribution, were studied. It was found that efficiency of doping reaction depends on the elemental oxygen content in the activated carbon. Relationships between nitrogen content, porous structure characteristics and electrodes electrochemical properties are demonstrated.

Keywords: activated carbons, low-temperature fuel cells, nitrogen doping, porous structure, supercapacitors

Procedia PDF Downloads 120