Search results for: measurement conversion
949 Back to Nature: Addressing the German Nudist Movement’s Colonial Past and Its Repercussions
Authors: Saskia Köbschall
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The idea of ‘being close to nature’ and the ways of achieving this proximity are socially and historically constructed, as are notions of nakedness and nudity. During the colonial period, nudity and clothedness functioned as instruments of racial domination. Nakedness became central to the colonialists’ thinking, to their binary of the ‘civilized’ and those ‘close to nature’, therefore turning the level of perceived unclothedness into a measurement of ‘civilization'. While being ‘one with nature’ continued to be a criterion of backwardness in the colonies, it emerged as a futuristic and avant-garde endeavor in the metropole: In Germany, at the height of its colonial expansion, the Life Reform Movement (Lebensreformbewegung) called for the liberation of the white body from the ‘constraints of civilization’, for its ‘return to nature’ via practices like nudism. Despite this simultaneity, the scholarship of the life reform and the nudist movement in particular does not address the colonial past of the movement or its repercussions in the present. Taking the biography of prominent life reformist Hans Paasche (1881 - 1920) as a starting point, this paper explores the work of imperial legacies in the history and present of the German nudist movement. Paasche started his career as a German colonial officer, participating in the brutal obliteration of the Maji-Maji uprising (1905/06) that claimed the lives of nearly 200.000 people. Once a passionate game hunter, he later became a known nature conservationist; once a self-proclaimed explorer of Africa, he later became one of the most prominent advocates of nudism and vegetarianism. The paper joins conceptual and historical research in order to address the German nudist movement’s colonial past and understand its repercussions in the present.Keywords: Germany, life reform, colonialism, archives, nudity, nature
Procedia PDF Downloads 95948 Three-Dimensional Vibration Characteristics of Piezoelectric Semi-Spherical Shell
Authors: Yu-Hsi Huang, Ying-Der Tsai
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Piezoelectric circular plates can provide out-of-plane vibrational displacements on low frequency and in-plane vibrational displacements on high frequency. Piezoelectric semi-spherical shell, which is double-curvature structure, can induce three-dimensional vibrational displacements over a large frequency range. In this study, three-dimensional vibrational characteristics of piezoelectric semi-spherical shells with free boundary conditions are investigated using three experimental methods and finite element numerical modeling. For the experimental measurements, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) is used to obtain resonant frequencies and radial and azimuthal mode shapes. This optical technique utilizes a full-field and non-contact optical system that measures both the natural frequency and corresponding vibration mode shape simultaneously in real time. The second experimental technique used, laser displacement meter is a point-wise displacement measurement method that determines the resonant frequencies of the piezoelectric shell. An impedance analyzer is used to determine the in-plane resonant frequencies of the piezoelectric semi-spherical shell. The experimental results of the resonant frequencies and mode shapes for the piezoelectric shell are verified with the result from finite element analysis. Excellent agreement between the experimental measurements and numerical calculation is presented on the three-dimensional vibrational characteristics of the piezoelectric semi-spherical shell.Keywords: piezoelectric semi-spherical shell, mode shape, resonant frequency, electronic speckle pattern interferometry, radial vibration, azimuthal vibration
Procedia PDF Downloads 234947 Comparative Analysis of the Third Generation of Research Data for Evaluation of Solar Energy Potential
Authors: Claudineia Brazil, Elison Eduardo Jardim Bierhals, Luciane Teresa Salvi, Rafael Haag
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Renewable energy sources are dependent on climatic variability, so for adequate energy planning, observations of the meteorological variables are required, preferably representing long-period series. Despite the scientific and technological advances that meteorological measurement systems have undergone in the last decades, there is still a considerable lack of meteorological observations that form series of long periods. The reanalysis is a system of assimilation of data prepared using general atmospheric circulation models, based on the combination of data collected at surface stations, ocean buoys, satellites and radiosondes, allowing the production of long period data, for a wide gamma. The third generation of reanalysis data emerged in 2010, among them is the Climate Forecast System Reanalysis (CFSR) developed by the National Centers for Environmental Prediction (NCEP), these data have a spatial resolution of 0.50 x 0.50. In order to overcome these difficulties, it aims to evaluate the performance of solar radiation estimation through alternative data bases, such as data from Reanalysis and from meteorological satellites that satisfactorily meet the absence of observations of solar radiation at global and/or regional level. The results of the analysis of the solar radiation data indicated that the reanalysis data of the CFSR model presented a good performance in relation to the observed data, with determination coefficient around 0.90. Therefore, it is concluded that these data have the potential to be used as an alternative source in locations with no seasons or long series of solar radiation, important for the evaluation of solar energy potential.Keywords: climate, reanalysis, renewable energy, solar radiation
Procedia PDF Downloads 209946 The Implementation of Level of Service for Development of Kuala Lumpur Transit Information System using GIS
Authors: Mokhtar Azizi
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Due to heavy traffic and congested roads, it is crucial that the most popular main public transport services in Kuala Lumpur i.e. Putra LRT, Star LRT, KTM Commuter, KL Monorail and Rapid Bus must be continuously monitored and improved to fulfill the rider’s requirement and kept updated by the transit agencies. Evaluation on the current status of the services has been determined out by calculating the transit supportive area (TSA) and level of service (LOS) for each transit station. This research study has carried out the TSA and LOS mapping based on GIS techniques. The detailed census data of the region along the line of services has been collected from the Department of Statistics Malaysia for this purpose. The service coverage has been decided by 400 meters buffer zone for bus stations and 800 meters for rails station and railways in measurement the Quality of Service along the line of services. All the required information has been calculated by using the customized GIS software called Kuala Lumpur Transit Information System (KLTIS). The transit supportive area was calculated with the employment density at least 10 job/hectare or household density at 7.5 unit/hectare and total area covered by transit supportive area is 22516 hectare and the total area that is not supported by transit is 1718 hectare in Kuala Lumpur. The level of service is calculated with the percentage of transit supportive area served by transit for each station. In overall the percentage transit supportive areas served by transit for all the stations were less than 50% which falls in a very low level of service category. This research has proven its benefit by providing the current transit services operators with vital information for improvement of existing public transport services.Keywords: service coverage, transit supportive area, level of service, transit system
Procedia PDF Downloads 377945 Analysis of the Cutting Force with Ultrasonic Assisted Manufacturing of Steel (S235JR)
Authors: Philipp Zopf, Franz Haas
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Manufacturing of very hard and refractory materials like ceramics, glass or carbide poses particular challenges on tools and machines. The company Sauer GmbH developed especially for this application area ultrasonic tool holders working in a frequency range from 15 to 60 kHz and superimpose the common tool movement in the vertical axis. This technique causes a structural weakening in the contact area and facilitates the machining. The possibility of the force reduction for these special materials especially in drilling of carbide with diamond tools up to 30 percent made the authors try to expand the application range of this method. To make the results evaluable, the authors decide to start with existing processes in which the positive influence of the ultrasonic assistance is proven to understand the mechanism. The comparison of a grinding process the Institute use to machine materials mentioned in the beginning and steel could not be more different. In the first case, the authors use tools with geometrically undefined edges. In the second case, the edges are geometrically defined. To get valid results of the tests, the authors decide to investigate two manufacturing methods, drilling and milling. The main target of the investigation is to reduce the cutting force measured with a force measurement platform underneath the workpiece. Concerning to the direction of the ultrasonic assistance, the authors expect lower cutting forces and longer endurance of the tool in the drilling process. To verify the frequencies and the amplitudes an FFT-analysis is performed. It shows the increasing damping depending on the infeed rate of the tool. The reducing of amplitude of the cutting force comes along.Keywords: drilling, machining, milling, ultrasonic
Procedia PDF Downloads 274944 Shelf Life of Frozen Processed Foods for Extended Durability
Authors: Manfreda Gerardo, Pasquali Frederique, Pepe Tiziana, Anastasio Aniello, Ianieri Adriana
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The aim of the research was to evaluate the shelf life of a REPFED’s product (lasagna alla bolognese), developed as a product to be marketed fresh after defrosting. Three different samples were prepared: A, B and C, which presented differences in relation to the recipe, pasteurization technique and packaging on which the trend of the shelf-life indicator parameters was evaluated during a period of prolonged shelf life. The analytical plan involved the measurement of microbiological, chemical-physical and organoleptic parameters over 7 moments of storage selected in a period of 33 days. CBT, LAB, enterobacteria, E. coli, yeasts, molds, S. coagulase positive, B. cereus, Salmonella spp and L. monocytogenes, pH, Aw, Kreiss test, peroxides, atmosphere inside the packages, and organoleptic characteristics were determined. The results demonstrated the effect of post-packaging pasteurization on the shelf life of fresh from frozen products. However, the products pasteurized at 95°C in the absence of steam showed microbiological parameters that were not appropriate for an extended shelf life of up to 60 days. On the contrary, the samples pasteurized at 98°C with steam saturation and counterpressure showed values compatible with an extended shelf life. The results of the chemical-physical analyses highlighted how recipe and packaging affect the chemical-physical and organoleptic parameters. In conclusion, this preliminary study confirmed the effectiveness of post-packaging pasteurization treatments aimed at extending the shelf life of the product, helping the food company to occupy market niches even very distant from the production sites.Keywords: shelf life, REPFED’s product, extended durability, pasteurization
Procedia PDF Downloads 30943 Studying the Establishment of Knowledge Management Background Factors at Islamic Azad University, Behshahr Branch
Authors: Mohammad Reza Bagherzadeh, Mohammad Hossein Taheri
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Knowledge management serves as one of the great breakthroughs in information and knowledge era and given its outstanding features, successful organizations tends to adopt it. Therefore, to deal with knowledge management establishment in universities is of special importance. In this regard, the present research aims to shed lights on factors background knowledge management establishment at Islamic Azad University, Behshahr Branch (Northern Iran). Considering three factors information technology system, knowledge process system and organizational culture as a fundamental of knowledge management infrastructure, foregoing factors were evaluated individually. The present research was conducted in descriptive-survey manner and participants included all staffs and faculty members, so that according to Krejcie & Morgan table a sample size proportional to the population size was considered. The measurement tools included survey questionnaire whose reliability was calculated to 0.83 according to Cronbachs alpha. To data analysis, descriptive statistics such as frequency and its percentage tables, column charts, mean, standard deviation and as for inferential statistics Kolomogrov- Smirnov test and single T-test were used. The findings show that despite the good corporate culture as one of the three factors background the establishment of the knowledge management at Islamic Azad University Behshahr Branch, other two ones, including IT systems, and knowledge processes systems are characterized with adverse status. As a result, these factors have caused no necessary conditions for the establishment of Knowledge Management in the university provided.Keywords: knowledge management, information technology, knowledge processes, organizational culture, educational institutions
Procedia PDF Downloads 523942 Colorimetric Measurement of Dipeptidyl Peptidase IV (DPP IV) Activity via Peptide Capped Gold Nanoparticles
Authors: H. Aldewachi, M. Hines, M. McCulloch, N. Woodroofe, P. Gardiner
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DPP-IV is an enzyme whose expression is affected in a variety of diseases, therefore, has been identified as possible diagnostic or prognostic marker for various tumours, immunological, inflammatory, neuroendocrine, and viral diseases. Recently, DPP-IV enzyme has been identified as a novel target for type II diabetes treatment where the enzyme is involved. There is, therefore, a need to develop sensitive and specific methods that can be easily deployed for the screening of the enzyme either as a tool for drug screening or disease marker in biological samples. A variety of assays have been introduced for the determination of DPP-IV enzyme activity using chromogenic and fluorogenic substrates, nevertheless these assays either lack the required sensitivity especially in inhibited enzyme samples or displays low water solubility implying difficulty for use in vivo samples in addition to labour and time-consuming sample preparation. In this study, novel strategies based on exploiting the high extinction coefficient of gold nanoparticles (GNPs) are investigated in order to develop fast, specific and reliable enzymatic assay by investigating synthetic peptide sequences containing a DPP IV cleavage site and coupling them to GNPs. The DPP IV could be detected by colorimetric response of peptide capped GNPs (P-GNPS) that could be monitored by a UV-visible spectrophotometer or even naked eyes, and the detection limit could reach 0.01 unit/ml. The P-GNPs, when subjected to DPP IV, showed excellent selectivity compared to other proteins (thrombin and human serum albumin) , which led to prominent colour change. This provided a simple and effective colorimetric sensor for on-site and real-time detection of DPP IV.Keywords: gold nanoparticles, synthetic peptides, colorimetric detection, DPP-IV enzyme
Procedia PDF Downloads 303941 Effect of Iron Oxide Addition on the Solid-State Synthesis of Ye’Elimite
Authors: F. Z. Abir, M. Mesnaoui, Y. Abouliatim, L. Nibou, Y. El Hafiane, A. Smith
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The cement industry has been taking significant steps for years to reduce its carbon footprint by opting for an eco-friendly alternative such as Calcium Sulfoaluminate Cements (CSA). These binders, compared to Ordinary Portland Cements (OPC), have two advantages: reduction of the CO2 emissions and energy-saving because the sintering temperature of CSA cements is between 1250 and 1350 °C, which means 100 to 200 °C less than OPC. The aim of this work is to study the impurities effect, such as iron oxide, on the formation of the ye'elimite phase, which represents the main phase of Calcium Sulfoaluminate Cements and the consequence on its hydration. Several elaborations and characterization techniques were used to study the structure and microstructure of ye'elimite, such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), thermal analysis, specific surface area measurement, and electrical conductivity of diluted solutions. This study details the protocol for the solid-state synthesis of ye'elimite containing increasing amounts of iron (general formula: Ca4Al(6-2x)Fe2xSO16 with x = 0.00 to 1.13). Ye'elimite is formed by solid-state reactions between Al2O3, CaO and CaSO4 and the maximum ye'elimite content is reached at a sintering temperature of 1300 °C. The presence of iron promotes the formation of cubic ye'elimite at the expense of the orthorhombic phase. The total incorporation of iron in ye'elimite structure is possible when x < 0.12. Beyond this content, the ferritic phase (CaO)2(Al2O3,Fe2O3) appears as a minor phase and develops two different morphologies during cooling: dendritic crystals and melt morphology. The formation of the ferrous liquid phase affects the evolution of grain size of the ye’elimite and calcium aluminates.Keywords: calcium sulfoaluminate cement, ferritic phase, sintering, solid-state synthesis, ye’elimite
Procedia PDF Downloads 189940 Clouds Influence on Atmospheric Ozone from GOME-2 Satellite Measurements
Authors: S. M. Samkeyat Shohan
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This study is mainly focused on the determination and analysis of the photolysis rate of atmospheric, specifically tropospheric, ozone as function of cloud properties through-out the year 2007. The observational basis for ozone concentrations and cloud properties are the measurement data set of the Global Ozone Monitoring Experiment-2 (GOME-2) sensor on board the polar orbiting Metop-A satellite. Two different spectral ranges are used; ozone total column are calculated from the wavelength window 325 – 335 nm, while cloud properties, such as cloud top height (CTH) and cloud optical thick-ness (COT) are derived from the absorption band of molecular oxygen centered at 761 nm. Cloud fraction (CF) is derived from measurements in the ultraviolet, visible and near-infrared range of GOME-2. First, ozone concentrations above clouds are derived from ozone total columns, subtracting the contribution of stratospheric ozone and filtering those satellite measurements which have thin and low clouds. Then, the values of ozone photolysis derived from observations are compared with theoretical modeled results, in the latitudinal belt 5˚N-5˚S and 20˚N - 20˚S, as function of CF and COT. In general, good agreement is found between the data and the model, proving both the quality of the space-borne ozone and cloud properties as well as the modeling theory of ozone photolysis rate. The found discrepancies can, however, amount to approximately 15%. Latitudinal seasonal changes of photolysis rate of ozone are found to be negatively correlated to changes in upper-tropospheric ozone concentrations only in the autumn and summer months within the northern and southern tropical belts, respectively. This fact points to the entangled roles of temperature and nitrogen oxides in the ozone production, which are superimposed on its sole photolysis induced by thick and high clouds in the tropics.Keywords: cloud properties, photolysis rate, stratospheric ozone, tropospheric ozone
Procedia PDF Downloads 212939 The Morphological and Morphometrical Evaluation of the Bores That Transmit Emissary Veins in Terms of Surgery
Authors: Fikri Turk, Sahika Pinar Akyer, Mevci Ozdemir, Mehmet Bulent Ozdemir, Ilgaz Akdogan
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The complications such as bleeding, thrombosis and air embolism depend on injuries emissary veins is often encountered in surgery. Detailed descriptions of the mastoid foramen, occipital foramen, parietal foramen, posterior condylar canal and foramen vesalius are lacking in the literature. For this reason, the purpose of our study was to explore and represent the morphology and morphometry of these emissary foramina in order to prevent complications and to guide for surgeons. The present study was made on 60 dry human skull in the laboratories of Pamukkale University, Faculty of Medicine Department of Anatomy. After taken photograph of emissary foramens by Canon 650D professional camera, the evaluation and measurement’s these foramens made with Matlab program by computer. The overall prevalence of mastoid foramen was 90.52%, occipital foramen was 72.52%, parietal foramen was 42.85%, posterior condylar canal was 91.25% and foramen vesalius was 78.26%. The mean diameter of the mastoid foramen was 1.81±0.76 mm, occipital foramen was 1.20±0.25 mm, parietal foramen was 1.49±0.46 mm, posterior condylar canal was 2.83±1.33 mm and foramen vesalius was 1.74±0.60 mm. Distances between emissary foramina and fixed bony landmarks were measured. Emissary veins are important in clinic practice and surgical procedures because they act a route of spread of exracranial infection to the intracranial structures and these veins may be a significant bleeding during surgery of the skull and they can be source of thrombosis and air embolism. The detailed anatomical knowledge of these veins and foraminas may help to prevent complications and to guide for surgeons.Keywords: emissary foramina, mastoid foramen, occipital foramen, parietal foramen, posterior condylar canal, foramen vesalius, morphology, morphometry
Procedia PDF Downloads 365938 Evaluation of Food Safety and Security Practices in Midday Meal Programmes in Rural Areas of Beed District
Authors: Nuzhat Sultana M. B.
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Children are high-risk population in terms of food born illnesses. Food safety and security are the most important aspect of the success of midday meal programmes. Improper holding temperatures, cross-contamination and poor personal hygiene of food handlers are the main causes for the prevalence of pathogenic microbes in the food servicing areas. Two hundred and fifty preschool children in the age of 3 to 6 years from urban and rural anganwadies (pre school center) of Beed district were selected. Nutritional status of preschool children were assessed by anthropometrical and clinical measurement. The study assessed the food safety and security with the help of personal hygiene and other safety measures maintained by the food personnel working for midday meal programme, supplying mid meals to children in govt. anganwadies (pre school center). The hygiene level, sanitary condition and microbial quality of food and water, pathological health examination of food handlers were assessed with the help of checklist. A questionnaire was designed to evaluate knowledge, attitude, and practices of food handlers. Results of the study show that the nutritional and health status of rural and urban preschool children was very poor. Many of the food handlers were not aware of general knowledge and hygiene practices to be followed during food preparation areas. An intervention programme of education and importing training at workplaces has shown a positive impact on the outcome of safety and security practices and safe, hygienic practices of food handlers at workplace.Keywords: food, health, preschool children, safety, security
Procedia PDF Downloads 203937 Nanoliposomes in Photothermal Therapy: Advancements and Applications
Authors: Mehrnaz Mostafavi
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Nanoliposomes, minute lipid-based vesicles at the nano-scale, show promise in the realm of photothermal therapy (PTT). This study presents an extensive overview of nanoliposomes in PTT, exploring their distinct attributes and the significant progress in this therapeutic methodology. The research delves into the fundamental traits of nanoliposomes, emphasizing their adaptability, compatibility with biological systems, and their capacity to encapsulate diverse therapeutic substances. Specifically, it examines the integration of light-absorbing materials, like gold nanoparticles or organic dyes, into nanoliposomal formulations, enabling their efficacy as proficient agents for photothermal treatment Additionally, this paper elucidates the mechanisms involved in nanoliposome-mediated PTT, highlighting their capability to convert light energy into localized heat, facilitating the precise targeting of diseased cells or tissues. This precise regulation of light absorption and heat generation by nanoliposomes presents a non-invasive and precisely focused therapeutic approach, particularly in conditions like cancer. The study explores advancements in nanoliposomal formulations aimed at optimizing PTT outcomes. These advancements include strategies for improved stability, enhanced drug loading, and the targeted delivery of therapeutic agents to specific cells or tissues. Furthermore, the paper discusses multifunctional nanoliposomal systems, integrating imaging components or targeting elements for real-time monitoring and improved accuracy in PTT. Moreover, the review highlights recent preclinical and clinical trials showcasing the effectiveness and safety of nanoliposome-based PTT across various disease models. It also addresses challenges in clinical implementation, such as scalability, regulatory considerations, and long-term safety assessments. In conclusion, this paper underscores the substantial potential of nanoliposomes in advancing PTT as a promising therapeutic approach. Their distinctive characteristics, combined with their precise ability to convert light into heat, offer a tailored and efficient method for treating targeted diseases. The encouraging outcomes from preclinical studies pave the way for further exploration and potential clinical applications of nanoliposome-based PTT.Keywords: nanoliposomes, photothermal therapy, light absorption, heat conversion, therapeutic agents, targeted delivery, cancer therapy
Procedia PDF Downloads 114936 Revealing Thermal Degradation Characteristics of Distinctive Oligo-and Polisaccharides of Prebiotic Relevance
Authors: Attila Kiss, Erzsébet Némedi, Zoltán Naár
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As natural prebiotic (non-digestible) carbohydrates stimulate the growth of colon microflora and contribute to maintain the health of the host, analytical studies aiming at revealing the chemical behavior of these beneficial food components came to the forefront of interest. Food processing (especially baking) may lead to a significant conversion of the parent compounds, hence it is of utmost importance to characterize the transformation patterns and the plausible decomposition products formed by thermal degradation. The relevance of this work is confirmed by the wide-spread use of these carbohydrates (fructo-oligosaccharides, cyclodextrins, raffinose and resistant starch) in the food industry. More and more functional foodstuffs are being developed based on prebiotics as bioactive components. 12 different types of oligosaccharides have been investigated in order to reveal their thermal degradation characteristics. Different carbohydrate derivatives (D-fructose and D-glucose oligomers and polymers) have been exposed to elevated temperatures (150 °C 170 °C, 190 °C, 210 °C, and 220 °C) for 10 min. An advanced HPLC method was developed and used to identify the decomposition products of carbohydrates formed as a consequence of thermal treatment. Gradient elution was applied with binary solvent elution (acetonitrile, water) through amine based carbohydrate column. Evaporative light scattering (ELS) proved to be suitable for the reliable detection of the UV/VIS inactive carbohydrate degradation products. These experimental conditions and applied advanced techniques made it possible to survey all the formed intermediers. Change in oligomer distribution was established in cases of all studied prebiotics throughout the thermal treatments. The obtained results indicate increased extent of chain degradation of the carbohydrate moiety at elevated temperatures. Prevalence of oligomers with shorter chain length and even the formation of monomer sugars (D-glucose and D-fructose) might be observed at higher temperatures. Unique oligomer distributions, which have not been described previously are revealed in the case of each studied, specific carbohydrate, which might result in various prebiotic activities. Resistant starches exhibited high stability when being thermal treated. The degradation process has been modeled by a plausible reaction mechanism, in which proton catalyzed degradation and chain cleavage take place.Keywords: prebiotics, thermal degradation, fructo-oligosaccharide, HPLC, ELS detection
Procedia PDF Downloads 306935 Acoustic Emission Techniques in Monitoring Low-Speed Bearing Conditions
Authors: Faisal AlShammari, Abdulmajid Addali, Mosab Alrashed
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It is widely acknowledged that bearing failures are the primary reason for breakdowns in rotating machinery. These failures are extremely costly, particularly in terms of lost production. Roller bearings are widely used in industrial machinery and need to be maintained in good condition to ensure the continuing efficiency, effectiveness, and profitability of the production process. The research presented here is an investigation of the use of acoustic emission (AE) to monitor bearing conditions at low speeds. Many machines, particularly large, expensive machines operate at speeds below 100 rpm, and such machines are important to the industry. However, the overwhelming proportion of studies have investigated the use of AE techniques for condition monitoring of higher-speed machines (typically several hundred rpm, or even higher). Few researchers have investigated the application of these techniques to low-speed machines ( < 100 rpm). This paper addressed this omission and has established which, of the available, AE techniques are suitable for the detection of incipient faults and measurement of fault growth in low-speed bearings. The first objective of this paper program was to assess the applicability of AE techniques to monitor low-speed bearings. It was found that the measured statistical parameters successfully monitored bearing conditions at low speeds (10-100 rpm). The second objective was to identify which commonly used statistical parameters derived from the AE signal (RMS, kurtosis, amplitude and counts) could identify the onset of a fault in the out race. It was found that these parameters effectually identify the presence of a small fault seeded into the outer races. Also, it is concluded that rotational speed has a strong influence on the measured AE parameters but that they are entirely independent of the load under such load and speed conditions.Keywords: acoustic emission, condition monitoring, NDT, statistical analysis
Procedia PDF Downloads 248934 Assessment of Biofuel Feedstock Production on Arkansas State Highway Transportation Department's Marginalized Lands
Authors: Ross J. Maestas
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Biofuels are derived from multiple renewable bioenergy feedstocks including animal fats, wood, starchy grains, and oil seeds. Transportation agencies have considered growing the latter two on underutilized and nontraditional lands that they manage, such as in the Right of Way (ROW), abandoned weigh stations, and at maintenance yards. These crops provide the opportunity to generate revenue or supplement fuel once converted and offer a solution to increasing fuel costs and instability by creating a ‘home-grown’ alternative. Biofuels are non-toxic, biodegradable, and emit less Green House Gasses (GHG) than fossil fuels, therefore allowing agencies to meet sustainability goals and regulations. Furthermore, they enable land managers to achieve soil erosion and roadside aesthetic strategies. The research sought to understand if the cultivation of a biofuel feedstock within the Arkansas State Highway Transportation Department’s (AHTD) managed and marginalized lands is feasible by identifying potential land areas and crops. To determine potential plots the parcel data was downloaded from Arkansas’s GIS office. ArcGIS was used to query the data for all variations of the names of property owned by AHTD and a KML file was created that identifies the queried parcel data in Google Earth. Furthermore, biofuel refineries in the state were identified to optimize the harvest to transesterification process. Agricultural data was collected from federal and state agencies and universities to assess various oil seed crops suitable for conversion and suited to grow in Arkansas’s climate and ROW conditions. Research data determined that soybean is the best adapted biofuel feedstock for Arkansas with camelina and canola showing possibilities as well. Agriculture is Arkansas’s largest industry and soybean is grown in over half of the state’s counties. Successful cultivation of a feedstock in the aforementioned areas could potentially offer significant employment opportunity for which the skilled farmers already exist. Based on compiled data, AHTD manages 21,489 acres of marginalized land. The result of the feasibility assessment offer suggestions and guidance should AHTD decide to further investigate this type of initiative.Keywords: Arkansas highways, biofuels, renewable energy initiative, marginalized lands
Procedia PDF Downloads 329933 Measurement of Asphalt Pavement Temperature to Find out the Proper Asphalt Binder Performance Grade to the Asphalt Mixtures in Southern Desert of Libya
Authors: Khlifa El Atrash, Gabriel Assaf
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Most developing countries use volumetric analysis in designing asphalt mixtures, which can also be upgraded in hot arid weather. However, in order to be effective, it should include many important aspects which are materials, environment, and method of construction. The overall intent of the work reported in this study is to test different asphalt mixtures while taking into consideration the environment, type and source of material, tools, equipment, and the construction method. In this study, several tests were conducted on many samples that were carefully prepared under the expected traffic loads and temperatures in a dry hot climate. Several asphalt concrete mixtures were designed using two different binders. These mixtures were analyzed under two types of tests - Complex Modulus and Rutting test - to evaluate the hot mix asphalt properties under the represented temperatures and traffic load in Libya. These factors play an important role to improve the pavement performances in a hot climate weather based on the properties of the asphalt mixture, climate, and traffic load. This research summarized some recommendations for making asphalt mixtures used in hot dry areas. Such asphalt mixtures should use asphalt binder which is less affected by pavement temperature change and traffic load. The properties of the mixture, such as durability, deformation, air voids and performance, largely depend on the type of materials, environment, and mixing method. These properties, in turn, affect the pavement performance. Therefore, this study is aimed to develop a method for designing an asphalt mixture that takes into account field loading, various stresses, and temperature spectrums.Keywords: volumetric analysis, pavement performances, hot climate, asphalt mixture, traffic load
Procedia PDF Downloads 309932 The Impact of Land Use Ex-Concession to the Environment in Dharmasraya District, West Sumatra Province, Indonesia
Authors: Yurike, Yonariza, Rudi Febriamansyah, Syafruddin Karimi
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Forest is a natural resource that has an important function as a supporting element of human life. Forest degradation enormous impact on global warming is a reality we have experienced together, that disruption of ecosystems, extreme weather conditions, disruption of water management system watersheds and the threat of natural disasters as floods, landslides and droughts, even disruption food security. Dharmasraya is a district in the province of West Sumatra, which has an area of 92.150 ha of forest, which is largely a former production forest concessions (Forest Management Rights) which is supposed to be a secondary forest. This study answers about the impact of land use in the former concession area Dharmasraya on the environment. The methodology used is the household survey, key informants, and satellite data / GIS. From the results of the study, the former concession area in Dharmasraya experienced a reduction of forest cover over time significantly. Forest concessions should be secondary forests in Dharmasraya, now turned conversion to oil palm plantations. Population pressures and growing economic pressures, resulting in more intensive harvesting. As a result of these forest disturbances caused changes in forest functions. These changes put more emphasis towards economic function by ignoring social functions or ecological function. Society prefers to maximize their benefits today and pay less attention to the protection of natural resources. This causes global warming is increasing and this is not only felt by people around Dharmasraya but also the world. Land clearing by the community through a process in slash and burn. This fire was observed by NOAA satellites and recorded by the Forest Service of West Sumatra. This demonstrates the ability of trees felled trees to absorb carbon dioxide (CO2) to be lost, even with forest fires accounted for carbon dioxide emitted into the air, and this has an impact on global warming. In addition to the change of control of land into oil palm plantations water service has been poor, people began to trouble the water and oil palm plantations are located in the watershed caused the river dried up. Through the findings of this study is expected to contribute ideas to the policy makers to pay more attention to the former concession forest management as the prevention or reduction of global warming.Keywords: climate change, community, concession forests, environment
Procedia PDF Downloads 328931 Object-Based Image Analysis for Gully-Affected Area Detection in the Hilly Loess Plateau Region of China Using Unmanned Aerial Vehicle
Authors: Hu Ding, Kai Liu, Guoan Tang
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The Chinese Loess Plateau suffers from serious gully erosion induced by natural and human causes. Gully features detection including gully-affected area and its two dimension parameters (length, width, area et al.), is a significant task not only for researchers but also for policy-makers. This study aims at gully-affected area detection in three catchments of Chinese Loess Plateau, which were selected in Changwu, Ansai, and Suide by using unmanned aerial vehicle (UAV). The methodology includes a sequence of UAV data generation, image segmentation, feature calculation and selection, and random forest classification. Two experiments were conducted to investigate the influences of segmentation strategy and feature selection. Results showed that vertical and horizontal root-mean-square errors were below 0.5 and 0.2 m, respectively, which were ideal for the Loess Plateau region. The segmentation strategy adopted in this paper, which considers the topographic information, and optimal parameter combination can improve the segmentation results. Besides, the overall extraction accuracy in Changwu, Ansai, and Suide achieved was 84.62%, 86.46%, and 93.06%, respectively, which indicated that the proposed method for detecting gully-affected area is more objective and effective than traditional methods. This study demonstrated that UAV can bridge the gap between field measurement and satellite-based remote sensing, obtaining a balance in resolution and efficiency for catchment-scale gully erosion research.Keywords: unmanned aerial vehicle (UAV), object-analysis image analysis, gully erosion, gully-affected area, Loess Plateau, random forest
Procedia PDF Downloads 218930 Bone Mineral Density in Type 2 Diabetes Mellitus Postmenopausal Egyptian Female Patients: Correlation with Fetuin-A Level and Metabolic Parameters
Authors: Ahmed A. M. Shoaib, Heba A. Esaily, Mahmoud M. Emara, Eman A. E. Badr, Amany S. Khalifa, Mayada M. M., Abdel-Raizk
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Background: DM is associated with metabolic bone diseases, osteoporosis, low-impact fractures and falls in geriatrics. Fetuin-A, which is a serum protein produced by the liver and promotes bone mineralization, is an independent risk factor for type 2 diabetes. Aim: Evaluation of fetuin-A level and bone mineral density in postmenopausal Egyptian female patients with type 2 diabetes mellitus and their correlation with each other & with other metabolic parameters. Patients and methods: Seventy postmenopausal female patients with type II diabetes and thirty postmenopausal female as control were included in this study. Measurement of Fetuin-A together with metabolic parameters and DXA in wrist, hip and spine, ALP, CBC, FBS, PP2H and HBA1c was done in all participants. Results: - Fetuin-A level was found to be highly significant (p< 0.001) between diabetic and nondiabetic groups and negatively correlated with BMD in spine. No difference in BMD was found between patients and control groups while significant negative correlation was found between FBS and hip BMD (<0.05) and between 2hpp and HBA1c with spine BMD in the diabetic group (<0.05). Osteoporosis represented 12.9% in spine area and 7.2% in hip and wrist areas in diabetic patients, while osteopenia were found in 58.5%, 57.1%, and 37.1% in diabetic patients in spine, wrist, and hip respectively. Conclusion: - type II diabetes cannot be considered as a risk factor for osteoporosis; while glycemic parameters (FBS, 2hpp & HBA1c) and serum Fetuin-A levels were correlated with BMD in diabetics. Good glycemic control can be protective against osteoporosis in diabetic elderly.Keywords: fetuin-A, BMD, postmenopausal, DM type II
Procedia PDF Downloads 267929 The Impact of Preference-Based Employee Deployment toward Employee Satisfaction and Organizational Performance: Case Study in Directorate General of State Asset Management, Ministry of Finance of the Republic of Indonesia
Authors: Rahmat Irawan, Mundhir Hanifsyam Harahap, Andar Ristabet Hesda
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As a public sector organization in Indonesia, Directorate General of State Asset Management (DGSAM) which is a unit under the Ministry of Finance of The Republic of Indonesia, has many constraints in managing its employees. While private organizations are able to conduct a human resource management as the best practice, DGSAM is limited by many regulations, especially about punishment and lay off policy for under-performance employees. Therefore, since 2015, DGSAM tries to implement a new and uncommon approach considering employees’ preference to encourage the motivation and performance of employees. DGSAM’s employees may propose the job places, and DGSAM considers them in deciding employees deployment. This study tries to determine the impact of preference-based approach toward employees’ satisfaction and organizational performance. This study uses quantitative approaches by regression analysis to measure the impact of deployment toward satisfaction of deployed employees and performance change of related units in DGSAM. The result of this study shows that preference-based approach significantly improves employees’ satisfaction and performance of related units as well. Based on the results of this study, it can be suggested that the approach is able to be implemented in the wider scope of the Ministry of Finance of The Republic of Indonesia and whole public sector organization in Indonesia. However, this study only focuses on short term measurement, so it is suggested to do further study to analyze the long-term impact.Keywords: employee deployment, employee satisfaction, human resource management, organizational performance, preference-based approach
Procedia PDF Downloads 333928 Lung HRCT Pattern Classification for Cystic Fibrosis Using a Convolutional Neural Network
Authors: Parisa Mansour
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Cystic fibrosis (CF) is one of the most common autosomal recessive diseases among whites. It mostly affects the lungs, causing infections and inflammation that account for 90% of deaths in CF patients. Because of this high variability in clinical presentation and organ involvement, investigating treatment responses and evaluating lung changes over time is critical to preventing CF progression. High-resolution computed tomography (HRCT) greatly facilitates the assessment of lung disease progression in CF patients. Recently, artificial intelligence was used to analyze chest CT scans of CF patients. In this paper, we propose a convolutional neural network (CNN) approach to classify CF lung patterns in HRCT images. The proposed network consists of two convolutional layers with 3 × 3 kernels and maximally connected in each layer, followed by two dense layers with 1024 and 10 neurons, respectively. The softmax layer prepares a predicted output probability distribution between classes. This layer has three exits corresponding to the categories of normal (healthy), bronchitis and inflammation. To train and evaluate the network, we constructed a patch-based dataset extracted from more than 1100 lung HRCT slices obtained from 45 CF patients. Comparative evaluation showed the effectiveness of the proposed CNN compared to its close peers. Classification accuracy, average sensitivity and specificity of 93.64%, 93.47% and 96.61% were achieved, indicating the potential of CNNs in analyzing lung CF patterns and monitoring lung health. In addition, the visual features extracted by our proposed method can be useful for automatic measurement and finally evaluation of the severity of CF patterns in lung HRCT images.Keywords: HRCT, CF, cystic fibrosis, chest CT, artificial intelligence
Procedia PDF Downloads 67927 Effects of Body Positioning on Videofluoroscopic Barium Esophagram in Healthy Cats
Authors: Hyeona Kim, Kichang Lee, Seunghee Lee, Jeongsu An, Kyungjun Min
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Contrast videofluoroscopy is the diagnostic imaging technique for evaluating cat with dysphagia. Generally, videofluoroscopic studies have been done with the cat restrained in lateral recumbency. It is different from the neutral position such as standing or sternal recumbency which is actual swallowing posture. We hypothesized that measurement of esophageal transit and peristalsis would be affected by body position. This experimental study analyzed the imaging findings of barium esophagram in 5 cats. Each cat underwent videofluoroscopy during swallowing of liquid barium and barium-soaked kibble in standing position and lateral recumbency. Esophageal transit time and the number of esophageal peristaltic waves were compared among body positions. Transit time in the cervical esophagus (0.57s), cranial thoracic esophagus (2.5s), and caudal thoracic esophagus(1.10s) was delayed when cats were in lateral recumbency for liquid barium. For kibble, transit time was more delayed than that of liquid through the entire esophagus in lateral recumbency. Liquid and kibble frequently started to delay at thoracic inlet region, transit time in the thoracic esophagus was significantly delayed than the cervical esophagus. In standing position, 60.2% of liquid swallows stimulated primary esophageal peristalsis. In lateral recumbency, 50.5% of liquid swallows stimulated primary esophageal peristalsis. Other variables were not significantly different. Lateral body positioning increases entire esophageal transit time and thoracic esophageal transit time is most significantly delayed. Thus, lateral recumbency decreases the number of primary esophageal peristalsis.Keywords: barium esophagram, body positioning, cat, videofluoroscopy
Procedia PDF Downloads 202926 Formation of Nanochannels by Heavy Ions in Graphene Oxide Reinforced Carboxymethylcellulose Membranes for Proton Exchange Membrane Fuel Cells Applications
Authors: B. Kurbanova, M. Karibayev, N. Almas, K. Ospanov, K. Aimaganbetov, T. Kuanyshbekov, K. Akatan, S. Kabdrakhmanova
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Proton exchange membranes (PEMs) operating at high temperatures above 100 °C with the excellent mechanical, chemical and thermochemical stability have been received much attention, because of their practical application of proton exchange membrane fuel cells (PEMFCs). Nowadays, a huge number of polymers and polymer-mixed various membranes have been investigated for this application, all of which offer both pros and cons. However, PEMFCs are still lack of ideal membranes with unique properties. In this work, carboxymethylcellulose (CMC) based membranes with dispersive graphene oxide (GO) sheets were fabricated and investigated for PEMFCs application. These membranes and pristine GO were studied by a combination of XRD, XPS, Raman, Brillouin, FTIR, thermo-mechanical analysis (TGA and Dynamic Mechanical Analysis) and SEM microscopy, while substantial studies on the proton transport properties were provided by Electrochemical Impedance Spectroscopy (EIS) measurements. It was revealed that the addition of CMC to the GO boosts proton conductivity of the whole membrane, while GO provides good mechanical and thermomechanical stability to the membrane. Further, the continuous and ordered nanochannels with well-tailored chemical structures were obtained by irradiation of heavy ions Kr⁺¹⁷ with an energy of 1.75 MeV/nucleon on the heavy ion accelerator. The formation of these nanochannels led to the significant increase of proton conductivity at 50% Relative Humidity. Also, FTIR and XPS measurement results show that ion irradiation eliminated the GO’s surface oxygen chemical bonds (C=O, C-O), and led to the formation of C = C, C – C bonds, whereas these changes connected with an increase in conductivity.Keywords: proton exchange membranes, graphene oxide, fuel cells, carboxymethylcellulose, ion irradiation
Procedia PDF Downloads 92925 Effect of the Vertical Pressure on the Electrical Behaviour of the Micro-Copper Polyurethane Composite Films
Authors: Saeid Mehvari, Yolanda Sanchez-Vicente, Sergio González Sánchez, Khalid Lafdi
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Abstract- Materials with a combination of transparency, electrical conductivity, and flexibility are required in the growing electronic sector. In this research, electrically conductive and flexible films have been prepared. These composite films consist of dispersing micro-copper particles into polyurethane (PU) matrix. Two sets of samples were made using both spin coating technique (sample thickness lower than 30 μm) and materials casting (sample thickness lower than 100 μm). Copper concentrations in the PU matrix varied from 0.5 to 20% by volume. The dispersion of micro-copper particles into polyurethane (PU) matrix were characterised using optical microscope and scanning electron microscope. The electrical conductivity measurement was carried out using home-made multimeter set up under pressures from 1 to 20 kPa through thickness and in plane direction. It seems that samples made by casting were not conductive. However, the sample made by spin coating shows through-thickness conductivity when they are under pressure. The results showed that spin-coated films with higher concentration of 2 vol. % of copper displayed a significant increase in the conductivity value, known as percolation threshold. The maximum conductivity of 7.2 × 10-1 S∙m-1 was reached at concentrations of filler with 20 vol. % at 20kPa. A semi-empirical model with adjustable coefficients was used to fit and predict the electrical behaviour of composites. For the first time, the finite element method based on the representative volume element (FE-RVE) was successfully used to predict their electrical behaviour under applied pressures. Keywords: electrical conductivity, micro copper, numerical simulation, percolation threshold, polyurethane, RVE model
Procedia PDF Downloads 197924 Harmonic Assessment and Mitigation in Medical Diagonesis Equipment
Authors: S. S. Adamu, H. S. Muhammad, D. S. Shuaibu
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Poor power quality in electrical power systems can lead to medical equipment at healthcare centres to malfunction and present wrong medical diagnosis. Equipment such as X-rays, computerized axial tomography, etc. can pollute the system due to their high level of harmonics production, which may cause a number of undesirable effects like heating, equipment damages and electromagnetic interferences. The conventional approach of mitigation uses passive inductor/capacitor (LC) filters, which has some drawbacks such as, large sizes, resonance problems and fixed compensation behaviours. The current trends of solutions generally employ active power filters using suitable control algorithms. This work focuses on assessing the level of Total Harmonic Distortion (THD) on medical facilities and various ways of mitigation, using radiology unit of an existing hospital as a case study. The measurement of the harmonics is conducted with a power quality analyzer at the point of common coupling (PCC). The levels of measured THD are found to be higher than the IEEE 519-1992 standard limits. The system is then modelled as a harmonic current source using MATLAB/SIMULINK. To mitigate the unwanted harmonic currents a shunt active filter is developed using synchronous detection algorithm to extract the fundamental component of the source currents. Fuzzy logic controller is then developed to control the filter. The THD without the active power filter are validated using the measured values. The THD with the developed filter show that the harmonics are now within the recommended limits.Keywords: power quality, total harmonics distortion, shunt active filters, fuzzy logic
Procedia PDF Downloads 479923 Experimental Monitoring of the Parameters of the Ionosphere in the Local Area Using the Results of Multifrequency GNSS-Measurements
Authors: Andrey Kupriyanov
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In recent years, much attention has been paid to the problems of ionospheric disturbances and their influence on the signals of global navigation satellite systems (GNSS) around the world. This is due to the increase in solar activity, the expansion of the scope of GNSS, the emergence of new satellite systems, the introduction of new frequencies and many others. The influence of the Earth's ionosphere on the propagation of radio signals is an important factor in many applied fields of science and technology. The paper considers the application of the method of transionospheric sounding using measurements from signals from Global Navigation Satellite Systems to determine the TEC distribution and scintillations of the ionospheric layers. To calculate these parameters, the International Reference Ionosphere (IRI) model of the ionosphere, refined in the local area, is used. The organization of operational monitoring of ionospheric parameters is analyzed using several NovAtel GPStation6 base stations. It allows performing primary processing of GNSS measurement data, calculating TEC and fixing scintillation moments, modeling the ionosphere using the obtained data, storing data and performing ionospheric correction in measurements. As a result of the study, it was proved that the use of the transionospheric sounding method for reconstructing the altitude distribution of electron concentration in different altitude range and would provide operational information about the ionosphere, which is necessary for solving a number of practical problems in the field of many applications. Also, the use of multi-frequency multisystem GNSS equipment and special software will allow achieving the specified accuracy and volume of measurements.Keywords: global navigation satellite systems (GNSS), GPstation6, international reference ionosphere (IRI), ionosphere, scintillations, total electron content (TEC)
Procedia PDF Downloads 181922 Effect of Segregation on the Reaction Rate of Sewage Sludge Pyrolysis in a Bubbling Fluidized Bed
Authors: A. Soria-Verdugo, A. Morato-Godino, L. M. García-Gutiérrez, N. García-Hernando
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The evolution of the pyrolysis of sewage sludge in a fixed and a fluidized bed was analyzed using a novel measuring technique. This original measuring technique consists of installing the whole reactor over a precision scale, capable of measuring the mass of the complete reactor with enough precision to detect the mass released by the sewage sludge sample during its pyrolysis. The inert conditions required for the pyrolysis process were obtained supplying the bed with a nitrogen flowrate, and the bed temperature was adjusted to either 500 ºC or 600 ºC using a group of three electric resistors. The sewage sludge sample was supplied through the top of the bed in a batch of 10 g. The measurement of the mass released by the sewage sludge sample was employed to determine the evolution of the reaction rate during the pyrolysis, the total amount of volatile matter released, and the pyrolysis time. The pyrolysis tests of sewage sludge in the fluidized bed were conducted using two different bed materials of the same size but different densities: silica sand and sepiolite particles. The higher density of silica sand particles induces a flotsam behavior for the sewage sludge particles which move close to the bed surface. In contrast, the lower density of sepiolite produces a neutrally-buoyant behavior for the sewage sludge particles, which shows a proper circulation throughout the whole bed in this case. The analysis of the evolution of the pyrolysis process in both fluidized beds show that the pyrolysis is faster when buoyancy effects are negligible, i.e. in the bed conformed by sepiolite particles. Moreover, sepiolite was found to show an absorbent capability for the volatile matter released during the pyrolysis of sewage sludge.Keywords: bubbling fluidized bed, pyrolysis, reaction rate, segregation effects, sewage sludge
Procedia PDF Downloads 358921 Forest Soil Greenhouse Gas Real-Time Analysis Using Quadrupole Mass Spectrometry
Authors: Timothy L. Porter, T. Randy Dillingham
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Vegetation growth and decomposition, along with soil microbial activity play a complex role in the production of greenhouse gases originating in forest soils. The absorption or emission (respiration) of these gases is a function of many factors relating to the soils themselves, the plants, and the environment in which the plants are growing. For this study, we have constructed a battery-powered, portable field mass spectrometer for use in analyzing gases in the soils surrounding trees, plants, and other areas. We have used the instrument to sample in real-time the greenhouse gases carbon dioxide and methane in soils where plant life may be contributing to the production of gases such as methane. Gases such as isoprene, which may help correlate gas respiration to microbial activity have also been measured. The instrument is composed of a quadrupole mass spectrometer with part per billion or better sensitivity, coupled to battery-powered turbo and diaphragm pumps. A unique ambient air pressure differentially pumped intake apparatus allows for the real-time sampling of gases in the soils from the surface to several inches below the surface. Results show that this instrument is capable of instant, part-per-billion sensitivity measurement of carbon dioxide and methane in the near surface region of various forest soils. We have measured differences in soil respiration resulting from forest thinning, forest burning, and forest logging as compared to pristine, untouched forests. Further studies will include measurements of greenhouse gas respiration as a function of temperature, microbial activity as measured by isoprene production, and forest restoration after fire.Keywords: forest, soil, greenhouse, quadrupole
Procedia PDF Downloads 117920 DC Bus Voltage Ripple Control of Photo Voltaic Inverter in Low Voltage Ride-Trough Operation
Authors: Afshin Kadri
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Using Renewable Energy Resources (RES) as a type of DG unit is developing in distribution systems. The connection of these generation units to existing AC distribution systems changes the structure and some of the operational aspects of these grids. Most of the RES requires to power electronic-based interfaces for connection to AC systems. These interfaces consist of at least one DC/AC conversion unit. Nowadays, grid-connected inverters must have the required feature to support the grid under sag voltage conditions. There are two curves in these conditions that show the magnitude of the reactive component of current as a function of voltage drop value and the required minimum time value, which must be connected to the grid. This feature is named low voltage ride-through (LVRT). Implementing this feature causes problems in the operation of the inverter that increases the amplitude of high-frequency components of the injected current and working out of maximum power point in the photovoltaic panel connected inverters are some of them. The important phenomenon in these conditions is ripples in the DC bus voltage that affects the operation of the inverter directly and indirectly. The losses of DC bus capacitors which are electrolytic capacitors, cause increasing their temperature and decreasing its lifespan. In addition, if the inverter is connected to the photovoltaic panels directly and has the duty of maximum power point tracking, these ripples cause oscillations around the operating point and decrease the generating energy. Using a bidirectional converter in the DC bus, which works as a buck and boost converter and transfers the ripples to its DC bus, is the traditional method to eliminate these ripples. In spite of eliminating the ripples in the DC bus, this method cannot solve the problem of reliability because it uses an electrolytic capacitor in its DC bus. In this work, a control method is proposed which uses the bidirectional converter as the fourth leg of the inverter and eliminates the DC bus ripples using an injection of unbalanced currents into the grid. Moreover, the proposed method works based on constant power control. In this way, in addition, to supporting the amplitude of grid voltage, it stabilizes its frequency by injecting active power. Also, the proposed method can eliminate the DC bus ripples in deep voltage drops, which cause increasing the amplitude of the reference current more than the nominal current of the inverter. The amplitude of the injected current for the faulty phases in these conditions is kept at the nominal value and its phase, together with the phase and amplitude of the other phases, are adjusted, which at the end, the ripples in the DC bus are eliminated, however, the generated power decreases.Keywords: renewable energy resources, voltage drop value, DC bus ripples, bidirectional converter
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