Search results for: human resources cost
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 17264

Search results for: human resources cost

4754 Optimal Tamping for Railway Tracks, Reducing Railway Maintenance Expenditures by the Use of Integer Programming

Authors: Rui Li, Min Wen, Kim Bang Salling

Abstract:

For the modern railways, maintenance is critical for ensuring safety, train punctuality and overall capacity utilization. The cost of railway maintenance in Europe is high, on average between 30,000 – 100,000 Euros per kilometer per year. In order to reduce such maintenance expenditures, this paper presents a mixed 0-1 linear mathematical model designed to optimize the predictive railway tamping activities for ballast track in the planning horizon of three to four years. The objective function is to minimize the tamping machine actual costs. The approach of the research is using the simple dynamic model for modelling condition-based tamping process and the solution method for finding optimal condition-based tamping schedule. Seven technical and practical aspects are taken into account to schedule tamping: (1) track degradation of the standard deviation of the longitudinal level over time; (2) track geometrical alignment; (3) track quality thresholds based on the train speed limits; (4) the dependency of the track quality recovery on the track quality after tamping operation; (5) Tamping machine operation practices (6) tamping budgets and (7) differentiating the open track from the station sections. A Danish railway track between Odense and Fredericia with 42.6 km of length is applied for a time period of three and four years in the proposed maintenance model. The generated tamping schedule is reasonable and robust. Based on the result from the Danish railway corridor, the total costs can be reduced significantly (50%) than the previous model which is based on optimizing the number of tamping. The different maintenance strategies have been discussed in the paper. The analysis from the results obtained from the model also shows a longer period of predictive tamping planning has more optimal scheduling of maintenance actions than continuous short term preventive maintenance, namely yearly condition-based planning.

Keywords: integer programming, railway tamping, predictive maintenance model, preventive condition-based maintenance

Procedia PDF Downloads 425
4753 A Brief Exploration on the Green Urban Design for Carbon Neutrality

Authors: Gaoyuan Wang, Tian Chen

Abstract:

China’s emission peak and carbon neutrality strategies lead to the transformation of development patterns and call for new green urban design thinking. This paper begins by revealing the evolution of green urban design thinking during the periods of carbon enlightenment, carbon dependency, and carbon decoupling from the perspective of the energy transition. Combined with the current energy situation, national strengths, and technological trends, the emergence of green urban design towards carbon neutrality becomes inevitable. Based on the preliminary analysis of its connotation, the characteristics of the new type of green urban design are generalized as low-carbon orientation, carbon-related objects, carbon-reduction means, and carbon-control patterns. Its theory is briefly clarified in terms of the human-earth synergism, quality-energy interconnection, and form-flow interpromotion. Then, its mechanism is analyzed combined with the core tasks of carbon neutrality, and the scope of design issues is defined, including carbon flow mapping, carbon source regulation, carbon sink construction, and carbon emission management. Finally, a multi-scale spatial response system is proposed across the region, city, cluster, and neighborhood level. The discussion aims to provide support for the innovation of green urban design theories and methods in the context of peak neutrality.

Keywords: carbon neutrality, green urban design, energy transition, theoretical exploration

Procedia PDF Downloads 159
4752 Recent Developments in Artificial Intelligence and Information Communications Technology

Authors: Dolapo Adeyemo

Abstract:

Technology can be designed specifically for geriatrics and persons with disabilities or ICT accessibility solutions. Both solutions stand to benefit from advances in Artificial intelligence, which are computer systems that perform tasks that require human intelligence. Tasks such as decision making, visual perception, speech recognition, and even language translation are useful in both situation and will provide significant benefits to people with temporarily or permanent disabilities. This research’s goal is to review innovations focused on the use of artificial intelligence that bridges the accessibility gap in technology from a user-centered perspective. A mixed method approach that utilized a comprehensive review of academic literature on the subject combined with semi structure interviews of users, developers, and technology product owners. The internet of things and artificial intelligence technology is creating new opportunities in the assistive technology space and proving accessibility to existing technology. Device now more adaptable to the needs of the user by learning the behavior of users as they interact with the internet. Accessibility to devices have witnessed significant enhancements that continue to benefit people with disabilities. Examples of other advances identified are prosthetic limbs like robotic arms supported by artificial intelligence, route planning software for the visually impaired, and decision support tools for people with disabilities and even clinicians that provide care.

Keywords: ICT, IOT, accessibility solutions, universal design

Procedia PDF Downloads 73
4751 Early Initiation of Breastfeeding among Postpartum Mothers at Two Rwandan Hospitals

Authors: Joella Mukashyaka, Rose Mukarubayiza, Emmanuel Habumugisha, Francois-Xavier Sunday, Kellen Muganwa, Valens Mbarushimana, Pamela Meharry

Abstract:

Background: Breastfeeding in the first hour post-birth can decrease neonatal morbidity and mortality. Disease prevention and health outcomes differ immensely between newborns who receive human milk and those who do not. Rwanda has high breastfeeding rates, though factors associated with early initiation of breastfeeding (EIBF) are unknown. Objective: To assess factors associated with EIBF among mothers in immediate postpartum units at two hospitals. Methods: A cross-sectional study design and a convenience sample of 187 mothers were used. An interviewer-administered questionnaire was used for data collection. A Chi-square test showed the relationship between EIBF and sociodemographic factors. Results: The findings showed less than one quarter (20.5%) breastfed within the first hour after birth. The majority was < 25 years (52.4%), had some primary education (27.7%) employed (66.7%), urban dweller (58.1%), attendance of one ANC visit or more (81.3%), vaginal birth (58.8%), and did not receive EIBF health education (92.0%). The majority (78.5%) was too tired to initiate breastfeeding, and many supplemented (41.9%) due to perceived insufficient breastmilk. Conclusion: Most mothers did not initiate breastfeeding within the first hour after birth. Sociodemographic factors were associated with EIBF. A program to promote, protect, and support EIBF is urgently needed the community.

Keywords: breastfeeding, early initiation, neonates, morbidity, mortality, sub-Saharan Africa

Procedia PDF Downloads 66
4750 Activation of Mitophagy and Autophagy in Familial Forms of Parkinson's Disease, as a Potential Strategy for Cell Protection

Authors: Nafisa Komilova, Plamena Angelova, Andrey Abramov, Ulugbek Mirkhodjaev

Abstract:

Parkinson’s disease (PD) is a progressive neurodegenerative disorder which is induced by the loss of dopaminergic neurons in the midbrain. The mechanism of neurodegeneration is associated with the aggregation of misfolded proteins, oxidative stress, and mitochondrial disfunction. Considering this, the process of removal of unwanted organelles or proteins by autophagy is vitally important in neurons, and activation of these processes could be protective in PD. Short-time acidification of cytosol can activate mitophagy and autophagy, and here we used sodium pyruvate and sodium lactate in human fibroblasts with PD mutations (Pink1, Pink1/Park2, α-syn triplication, A53T) to induce changes in intracellular pH. We have found that both lactate and pyruvate in millimolar concentrations can induce short-time acidification of cytosol in these cells. It induced activation of mitophagy and autophagy in control and PD fibroblasts and protected against cell death. Importantly, the application of lactate to acute brain slices of control and Pink1 knockout mice also induced a reduction of pH in neurons and astrocytes that increase the level of mitophagy. Thus, acidification of cytosol by compounds which play important role in cell metabolism also can activate mitophagy and autophagy and protect cells in the familial form of PD.

Keywords: Parkinson's disease, mutations, mitophagy, autophagy

Procedia PDF Downloads 176
4749 Multi-Sensor Image Fusion for Visible and Infrared Thermal Images

Authors: Amit Kumar Happy

Abstract:

This paper is motivated by the importance of multi-sensor image fusion with a specific focus on infrared (IR) and visual image (VI) fusion for various applications, including military reconnaissance. Image fusion can be defined as the process of combining two or more source images into a single composite image with extended information content that improves visual perception or feature extraction. These images can be from different modalities like visible camera & IR thermal imager. While visible images are captured by reflected radiations in the visible spectrum, the thermal images are formed from thermal radiation (infrared) that may be reflected or self-emitted. A digital color camera captures the visible source image, and a thermal infrared camera acquires the thermal source image. In this paper, some image fusion algorithms based upon multi-scale transform (MST) and region-based selection rule with consistency verification have been proposed and presented. This research includes the implementation of the proposed image fusion algorithm in MATLAB along with a comparative analysis to decide the optimum number of levels for MST and the coefficient fusion rule. The results are presented, and several commonly used evaluation metrics are used to assess the suggested method's validity. Experiments show that the proposed approach is capable of producing good fusion results. While deploying our image fusion algorithm approaches, we observe several challenges from the popular image fusion methods. While high computational cost and complex processing steps of image fusion algorithms provide accurate fused results, they also make it hard to become deployed in systems and applications that require a real-time operation, high flexibility, and low computation ability. So, the methods presented in this paper offer good results with minimum time complexity.

Keywords: image fusion, IR thermal imager, multi-sensor, multi-scale transform

Procedia PDF Downloads 98
4748 The Effect of Exposure to High Noise Level on the Performance and Rate of Error in Manual Activities

Authors: Zahra Zamanian, Alireza Zamanian, Jafar Hasanzadeh

Abstract:

Background: Unwanted sound, as one of the most important physical factors in the majority of production units, imposes a great number of problems on the industrial workers. Sound is one of the environmental factors which can cause physical as well as psychological damages and also affects the individuals’ performance and productivity. Therefore, the present study aimed to determine the effect of noise exposure on human performance. Methods: The present study assessed the effect of noise on the performance of 50 students of Shiraz University of Medical Sciences (25 males and 25 females) at the sound pressures of 70, 90, and 110 dB by using two factors of physical features and the creation of different conditions of sound pressure source as well as applying Two-Arm coordination Test. Results: The results of the present study revealed no significant difference between male and female subjects as well as different conditions of creating sound pressure regarding the length of performance (p> 0.05). In addition, as the sound pressure increased, the length of performance increased, as well. According to the results, no significant difference was found between the performance at 70 and 90 dB. On the other hand, the performance at 110 dB was significantly different from the performance at 70 and 90 dB (p<0.05 and p<0.001). Conclusion: In general, as the sound pressure increases, the performance decreases which results in a considerable increase in the individuals’ rate of error.

Keywords: physical factors, two-arm coordination test, Shiraz University of Medical Sciences, noise

Procedia PDF Downloads 283
4747 Impact of Information and Communication Technology on Academic Performance of Senior Secondary Schools Students in Gwagwalada Area Council of Federal Capital Territory, Abuja

Authors: Suleiman Garba, Haruna Ishaku

Abstract:

Information and communication technology (ICT) includes any communication device encompassing: radio, television, cellular phones, computer, satellite systems and so on, as well as the various services and applications associated with them. The significance of ICT cannot be over-emphasized in education. The teaching and learning processes have integrated with the application of ICTs for effectiveness and enhancement of academic performance among the students. Today, as the educational sector is faced with series of changes and reforms, it was noted that the problem of information technology illiteracy was a serious one among the schools’ teachers in the country as it cuts across primary, secondary schools and tertiary institutions. This study investigated the impact of ICT on the academic performance of senior secondary schools students in Gwagwalada Area Council of Federal Capital Territory (FCT), Abuja. A sample of 120 SSS III students was involved in the study. They were selected by using simple random sampling technique. A questionnaire was developed and validated through expert judgement and reliability co-efficient of 0.81 was obtained. It was used to gather relevant data from the respondents. Findings revealed that there was positive impact of ICT on academic performance of senior secondary schools students. The findings indicated the causes of poor academic performance among the students as lack of qualified teachers to teach in schools, peer group influence, and bullying. Significantly, the findings revealed that ICT had a positive impact on students’ academic performance. The null hypotheses were tested using t-test at 0.05 level of significance. It was discovered that there was significant difference between male and female secondary schools’ students' impact of ICT on academic performance in Gwagawalada Area Council of FCT-Abuja. Based on these findings, some recommendations were made which include: adequate funds should be provided towards procurement of ICT resources, relevant textbooks to enhance students’ active participation in learning processes and students should be provided with internet accessibility at inexpensive rate so as to create a platform for accessing useful information in the pursuit of academic excellence.

Keywords: academic performance, impact, information communication technology, schools, students

Procedia PDF Downloads 208
4746 Value-Based Argumentation Frameworks and Judicial Moral Reasoning

Authors: Sonia Anand Knowlton

Abstract:

As the use of Artificial Intelligence is becoming increasingly integrated in virtually every area of life, the need and interest to logically formalize the law and judicial reasoning is growing tremendously. The study of argumentation frameworks (AFs) provides promise in this respect. AF’s provide a way of structuring human reasoning using a formal system of non-monotonic logic. P.M. Dung first introduced this framework and demonstrated that certain arguments must prevail and certain arguments must perish based on whether they are logically “attacked” by other arguments. Dung labelled the set of prevailing arguments as the “preferred extension” of the given argumentation framework. Trevor Bench-Capon’s Value-based Argumentation Frameworks extended Dung’s AF system by allowing arguments to derive their force from the promotion of “preferred” values. In VAF systems, the success of an attack from argument A to argument B (i.e., the triumph of argument A) requires that argument B does not promote a value that is preferred to argument A. There has been thorough discussion of the application of VAFs to the law within the computer science literature, mainly demonstrating that legal cases can be effectively mapped out using VAFs. This article analyses VAFs from a jurisprudential standpoint to provide a philosophical and theoretical analysis of what VAFs tell the legal community about the judicial reasoning, specifically distinguishing between legal and moral reasoning. It highlights the limitations of using VAFs to account for judicial moral reasoning in theory and in practice.

Keywords: nonmonotonic logic, legal formalization, computer science, artificial intelligence, morality

Procedia PDF Downloads 61
4745 The Molecular Analysis of Effect of Phytohormones and Spermidine on Tomato Growth under Biotic Stress

Authors: Rumana Keyani, Haleema Sadia, Asia Nosheen, Rabia Naz, Humaira Yasmin, Sidra Zahoor

Abstract:

Tomato is a significant crop of the world and is one of the staple foods of Pakistan. A vast number of plant pathogens from simple viruses to complex parasites cause diseases in tomatoes but fungal infection in our country is quite high. Sometimes the symptoms are too harsh destroying the crop altogether. Countries like our own with continuously increasing massive population and limited resources cannot afford such an economic loss. There is an array of morphological, genetic, biochemical and molecular processes involved in plant resistance mechanisms to biotic stress. The study of different metabolic pathways like Jasmonic acid (JA) pathways and most importantly signaling molecules like ROS/RNS and their redoxin enzymes i.e. TRX and NRX is crucial to disease management, contributing to healthy plant growth. So, improving tolerance in crop plants against biotic stresses is a dire need of our country and world as whole. In the current study, fungal pathogenic strains Alternaria solani and Rhizoctonia solani were used to inoculate tomatoes to check the defense responses of tomato plant against these pathogens at molecular as well as phenotypic level with jasmonic acid and spermidine pretreatment. All the growth parameters (root and shoot length, dry and weight root, shoot weight measured 7 days post-inoculation, exhibited that infection drastically declined the growth of the plant whereas jasmonic acid and spermidine assisted the plants to cope up with the infection. Thus, JA and Spermidine treatments maintained comparatively better growth factors. Antioxidant assays and expression analysis through real time quantitative PCR following time course experiment at 24, 48 and 72 hours intervals also exhibited that activation of JA defense genes and a polyamine Spermidine helps in mediating tomato responses against fungal infection when used alone but the two treatments combined mask the effect of each other.

Keywords: fungal infection, jasmonic acid defence, tomato, spermidine

Procedia PDF Downloads 107
4744 Design and Fabrication of a Programmable Stiffness-Sensitive Gripper for Object Handling

Authors: Mehdi Modabberifar, Sanaz Jabary, Mojtaba Ghodsi

Abstract:

Stiffness sensing is an important issue in medical diagnostic, robotics surgery, safe handling, and safe grasping of objects in production lines. Detecting and obtaining the characteristics in dwelling lumps embedded in a soft tissue and safe removing and handling of detected lumps is needed in surgery. Also in industry, grasping and handling an object without damaging in a place where it is not possible to access a human operator is very important. In this paper, a method for object handling is presented. It is based on the use of an intelligent gripper to detect the object stiffness and then setting a programmable force for grasping the object to move it. The main components of this system includes sensors (sensors for measuring force and displacement), electrical (electrical and electronic circuits, tactile data processing and force control system), mechanical (gripper mechanism and driving system for the gripper) and the display unit. The system uses a rotary potentiometer for measuring gripper displacement. A microcontroller using the feedback received by the load cell, mounted on the finger of the gripper, calculates the amount of stiffness, and then commands the gripper motor to apply a certain force on the object. Results of Experiments on some samples with different stiffness show that the gripper works successfully. The gripper can be used in haptic interfaces or robotic systems used for object handling.

Keywords: gripper, haptic, stiffness, robotic

Procedia PDF Downloads 345
4743 Inhibitory Impacts of Fulvic Acid-Coated Iron Oxide Nano Particles on the Amyloid Fibril Aggregations

Authors: Dalia Jomehpour, Sara Sheikhlary, Esmaeil Heydari, Mohammad Hossien Majles Ara

Abstract:

In this study, we report fulvic acid-coated iron oxide nanoparticles of 10.7 ± 2.7 nm size, which serve to inhibit amyloid fibrillation formation. Although the effect of fulvic acid on tau fibrils was investigated, to our best knowledge, its inhibitory impacts on amyloid aggregation formation have been assessed neither in-vitro nor in-vivo. On the other hand, iron oxide nanoparticles exhibit anti-amyloid activity on their own. This study investigates the inhibitory effect of fulvic acid coated iron oxide nanoparticles on amyloid aggregations formed from the commonly used in-vitro model, lysozyme from chicken egg white. FESEM, XRD, and FTIR characterization confirmed that fulvic acid was coated onto the surface of the nanoparticles. The inhibitory effects of the fulvic acid coated iron oxide nanoparticles were verified by Thioflavin T assay, circular dichroism (CD), and FESEM analysis. Furthermore, the toxicity of the nanoparticles on the neuroblastoma SH-SY5Y human cell line was assessed through an MTT assay. Our results indicate that fulvic acid coated iron oxide nanoparticles can efficiently inhibit the formation of amyloid aggregations while exhibiting negligible in-vitro toxicity; thus, they can be used as anti-amyloid agents in the development of the potential drug for neurodegenerative diseases.

Keywords: Alzheimer’s disease, fulvic acid coated iron oxide nanoparticles, fulvic acid, amyloid inhibitor, polyphenols

Procedia PDF Downloads 94
4742 Epidemiology of Toxoplasma gondii Infection in Animals of the Arabian Peninsula: A Systematic Review and Meta-Analysis

Authors: Ebtisam A. Al-Mslemani, Khalid A. Enan, Asmaa Abdelgadier, Nada Assaad, Zaynab Elhussein, Khalid Eltom

Abstract:

Background: Toxoplasma gondii (T. gondii) is a zoonotic parasite that can be transmitted from animals to humans, with felids acting as its definitive host. Thus, understanding the epidemiology of this parasite in animal populations is vital to controlling its transmission to humans as well as to other animal groups. Objectives: This systematic review and meta-analysis aim to summarise and analyse reports of T. gondii infection in animal species residing in the Arabian Peninsula. Methods: It was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), with relevant studies being retrieved from MEDLINE/PubMed, Scopus, Cochrane Library, Google Scholar and ScienceDirect. All articles published in Arabic or English languages between January 2000 and December 2020 were screened for eligibility. The random effects model was used to calculate the pooled prevalence of T. gondii infection in different animal populations which were found to harbour this infection. The critical appraisal tool for prevalence studies designed by the Joanna Briggs Institute (JBI) was used to assess the risk of bias in all included studies. Results: A total of 15 studies were retrieved, reporting prevalence estimates from 4 countries in this region and in 13 animal species. A quantitative meta-analysis estimated a pooled prevalence of 43% in felids [95% confidence interval (CI) = 23-64%, I2 index = 100%], 48% in sheep (95% CI = 27-70%, I2 = 99%) and 21% in camels (95% CI = 7-35%, I2 = 99%). Evidence of possible publication bias was found in both felids and sheep. Conclusions: This meta-analysis estimates a high prevalence of T. gondii infection in animal species that are of high economic and cultural importance to countries of this region. Hence, these findings provide valuable insight to public health authorities as well as economic and animal resources advisors in countries of the Arabian Peninsula.

Keywords: Arabian Peninsula, toxoplasma gondii, animals; meta-analysis, toxoplasmosis

Procedia PDF Downloads 61
4741 Assessing How Liberal Arts Colleges Can Teach Undergraduate Students about Key Issues in Migration, Immigration, and Human Rights

Authors: Hao Huang

Abstract:

INTRODUCTION: The Association of American Colleges and Universities (AACU) recommends the development of ‘high-impact practices,’ in an effort to increase rates of student retention and student engagement at undergraduate institutions. To achieve these goals, the Scripps College Humanities Institute and HI Fellows Seminar not only featured distinguished academics presenting their scholarship about current immigration policy and its consequences in the USA and around the world but integrated socially significant community leaders and creative activists/artivists in public talks, student workshops and collaborative art events. Students participated in experiential learning that involved guest personal presentations and discussions, oral history interviews that applied standard oral history methodologies, detailed cultural documentation, collaborative artistic interventions, and weekly posts in Internet Digital Learning Environment Sakai collaborative course forums and regular responses to other students’ comments. Our teaching pedagogies addressed the four learning styles outlined in Kolb’s Learning Style Inventory. PROJECT DESCRIPTION: Over the academic year 2017-18, the Scripps College Humanities Institute and HI Fellows Seminar presented a Fall 2017 topic, ‘The World at Our Doorsteps: Immigration and Deportation in Los Angeles’. Our purpose was to address how current federal government anti-immigration measures have affected many students of color, some of whom are immigrants, many of whom are related to and are friends with people who are impacted by the attitudes as well as the practices of the U.S. Citizenship and Immigration Services. In Spring 2018, we followed with the topic, ‘Exclusive Nationalisms: Global Migration and Immigration’. This addresses the rise of white supremacists who have ascended to position of power worldwide, in America, Europe, Russia, and xenophobic nationalisms in China, Myanmar and the Philippines. Recent scholarship has suggested the existence of categories of refugees beyond the political or social, who fit into the more inclusive category of migrants. ASSESSMENT METHODOLOGIES: Assessment methodologies not only included qualitative student interviews and quantitative student evaluations in standard rubric format, but also Outcome Assessments, Formative Evaluations, and Outside Guest Teacher feedback. These indicated that the most effective educational practices involved collaborative inquiry in undergraduate research, community-based learning, and capstone projects. Assessments of E-portfolios, written and oral coursework, and final creative projects with associated 10-12 page analytic paper revealed that students developed their understanding of how government and social organizations work; they developed communication skills that enhanced working with others from different backgrounds; they developed their ability to thoughtfully evaluate their course performance by adopting reflective practices; they gained analytic and interpretive skills that encouraged self-confidence and self- initiative not only academically, but also with regards to independent projects. CONCLUSION: Most importantly, the Scripps Humanities Institute experiential learning project spurred on real-world actions by our students, such as a public symposium on how to cope with bigots, a student tutoring program for immigrant staff children, student negotiations with the administration to establish meaningful, sustainable diversity and inclusion programs on-campus. Activism is not only to be taught to and for our students– it has to be enacted by our students.

Keywords: immigration, migration, human rights, learning assessment

Procedia PDF Downloads 117
4740 Haemocompatibility of Surface Modified AISI 316L Austenitic Stainless Steel Tested in Artificial Plasma

Authors: W. Walke, J. Przondziono, K. Nowińska

Abstract:

The study comprises evaluation of suitability of passive layer created on the surface of AISI 316L stainless steel for products that are intended to have contact with blood. For that purpose, prior to and after chemical passivation, samples were subject to 7 day exposure in artificial plasma at the temperature of T=37°C. Next, tests of metallic ions infiltration from the surface to the solution were performed. The tests were performed with application of spectrometer JY 2000, by Yobin – Yvon, employing Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). In order to characterize physical and chemical features of electrochemical processes taking place during exposure of samples to artificial plasma, tests with application of electrochemical impedance spectroscopy were suggested. The tests were performed with application of measuring unit equipped with potentiostat PGSTAT 302n with an attachment for impedance tests FRA2. Measurements were made in the environment simulating human blood at the temperature of T=37°C. Performed tests proved that application of chemical passivation process for AISI 316L stainless steel used for production of goods intended to have contact with blood is well-grounded and useful in order to improve safety of their usage.

Keywords: AISI 316L stainless steel, chemical passivation, artificial plasma, ions infiltration, EIS

Procedia PDF Downloads 251
4739 Developing a Process and Cost Model for Xanthan Biosynthesis from Bioethanol Production Waste Effluents

Authors: Bojana Ž. Bajić, Damjan G. Vučurović, Siniša N. Dodić, Jovana A. Grahovac, Jelena M. Dodić

Abstract:

Biosynthesis of xanthan, a microbial polysaccharide produced by Xanthomonas campestris, is characterized by the possibility of using non-specific carbohydrate substrates, which means different waste effluents can be used as a basis for the production media. Potential raw material sources for xanthan production come from industries with large amounts of waste effluents that are rich in compounds necessary for microorganism growth and multiplication. Taking into account the amount of waste effluents generated by the bioethanol industry and the fact that it contains a high inorganic and organic load it is clear that they represent a potential environmental pollutants if not properly treated. For this reason, it is necessary to develop new technologies which use wastes and wastewaters of one industry as raw materials for another industry. The result is not only a new product, but also reduction of pollution and environmental protection. Biotechnological production of xanthan, which consists of using biocatalysts to convert the bioethanol waste effluents into a high-value product, presents a possibility for sustainable development. This research uses scientific software developed for the modeling of biotechnological processes in order to design a xanthan production plant from bioethanol production waste effluents as raw material. The model was developed using SuperPro Designer® by using input data such as the composition of raw materials and products, defining unit operations, utility consumptions, etc., while obtaining capital and operating costs and the revenues from products to create a baseline production plant model. Results from this baseline model can help in the development of novel biopolymer production technologies. Additionally, a detailed economic analysis showed that this process for converting waste effluents into a high value product is economically viable. Therefore, the proposed model represents a useful tool for scaling up the process from the laboratory or pilot plant to a working industrial scale plant.

Keywords: biotechnology, process model, xanthan, waste effluents

Procedia PDF Downloads 333
4738 Implicit Responses for Assessment of Autism Based on Natural Behaviors Obtained Inside Immersive Virtual Environment

Authors: E. Olmos-Raya, A. Cascales Martínez, N. Minto de Sousa, M. Alcañiz Raya

Abstract:

The late detection and subjectivity of the assessment of Autism Spectrum Disorder (ASD) imposed a difficulty for the children’s clinical and familiar environment. The results showed in this paper, are part of a research project about the assessment and training of social skills in children with ASD, whose overall goal is the use of virtual environments together with physiological measures in order to find a new model of objective ASD assessment based on implicit brain processes measures. In particular, this work tries to contribute by studying the differences and changes in the Skin Conductance Response (SCR) and Eye Tracking (ET) between a typical development group (TD group) and an ASD group (ASD group) after several combined stimuli using a low cost Immersive Virtual Environment (IVE). Subjects were exposed to a virtual environment that showed natural scenes that stimulated visual, auditory and olfactory perceptual system. By exposing them to the IVE, subjects showed natural behaviors while measuring SCR and ET. This study compared measures of subjects diagnosed with ASD (N = 18) with a control group of subjects with typical development (N=10) when exposed to three different conditions: only visual (V), visual and auditory (VA) and visual, auditory and olfactory (VAO) stimulation. Correlations between SCR and ET measures were also correlated with the Autism Diagnostic Observation Schedule (ADOS) test. SCR measures showed significant differences among the experimental condition between groups. The ASD group presented higher level of SCR while we did not find significant differences between groups regarding DF. We found high significant correlations among all the experimental conditions in SCR measures and the subscale of ADOS test of imagination and symbolic thinking. Regarding the correlation between ET measures and ADOS test, the results showed significant relationship between VA condition and communication scores.

Keywords: autism, electrodermal activity, eye tracking, immersive virtual environment, virtual reality

Procedia PDF Downloads 126
4737 Energy Efficient Lighting in Educational Buildings through the Example of a High School in Istanbul

Authors: Nihan Gurel Ulusan

Abstract:

It is obvious that electrical energy, which is an inseparable part of modern day’s human and also the most important power source of our age, should be generated on a level that will suffice the nation’s requirements. The electrical energy used for a sustainable architectural design should be reduced as much as possible. Designing the buildings as energy efficient systems which aim at reducing the artificial illumination loads has been a current subject of our times as a result of concepts gaining importance like conscious consumption of energy sources, environment-friendly designs and sustainability. Reducing the consumption of electrical energy regarding the artificial lighting carries great significance, especially in the volumes which are used all day long like the educational buildings. Starting out with such an aim in this paper, the educational buildings are explored in terms of energy efficient lighting. Firstly, illumination techniques, illumination systems, light sources, luminaries, illumination controls and 'efficient energy' usage in lighting are mentioned. In addition, natural and artificial lighting systems used in educational buildings and also the spaces building up these kind buildings are examined in terms of energy efficient lighting. Lastly, the illumination properties of the school sample chosen for this study, Kağıthane Anadolu Lisesi, a typical high school in Istanbul, is observed. Suggestions are made in order to improve the system by evaluating the illumination properties of the classes with the survey carried out with the users.

Keywords: educational buildings, energy efficient, illumination techniques, lighting

Procedia PDF Downloads 268
4736 Direct Fed Microbes: A Better Approach to Maximize Utilization of Roughages in Tropical Ruminants

Authors: Muhammad Adeel Arshad, Shaukat Ali Bhatti, Faiz-ul Hassan

Abstract:

Manipulating microbial ecosystem in the rumen is considered as an important strategy to optimize production efficiency in ruminants. In the past, antibiotics and synthetic chemical compounds have been used for the manipulation of rumen fermentation. However, since the non-therapeutic use of antibiotics has been banned, efforts are being focused to search out safe alternative products. In tropics, crop residues and forage grazing are major dietary sources for ruminants. Poor digestibility and utilization of these feedstuffs by animals is a limiting factor to exploit the full potential of ruminants in this area. Hence, there is a need to enhance the utilization of these available feeding resources. One of the potential strategies in this regard is the use of direct-fed microbes. Bacteria and fungi are mostly used as direct-fed microbes to improve animal health and productivity. Commonly used bacterial species include lactic acid-producing and utilizing bacteria (Lactobacillus, Streptococcus, Enterococcus, Bifidobacterium, and Bacillus) and fungal species of yeast are Saccharomyces and Aspergillus. Direct-fed microbes modulate microbial balance in the gastrointestinal tract through the competitive exclusion of pathogenic species and favoring beneficial microbes. Improvement in weight gain and feed efficiency has been observed as a result of feeding direct-fed bacteria. The use of fungi as a direct-fed microbe may prevent excessive production of lactate and harmful oxygen in the rumen leading to better feed digestibility. However, the mechanistic mode of action for bacterial or fungal direct-fed microbes has not been established yet. Various reports have confirmed an increase in dry matter intake, milk yield, and milk contents in response to the administration of direct-fed microbes. However, the application of a direct-fed microbe has shown variable responses mainly attributed to dosages and strains of microbes. Nonetheless, it is concluded that the inclusion of direct-fed microbes may mediate the rumen ecosystem to manage lactic acid production and utilization in both clinical and sub-acute rumen acidosis.

Keywords: microbes, roughages, rumen, feed efficiency, production, fermentation

Procedia PDF Downloads 123
4735 Phytoremediation of artisanal gold mine tailings - Potential of Chrysopogon zizanioides and Andropogon gayanus in the Sahelian climate

Authors: Yamma Rose, Kone Martine, Yonli Arsène, Wanko Ngnien Adrien

Abstract:

Soil pollution and, consequently, water resources by micropollutants from gold mine tailings constitute a major threat in developing countries due to the lack of waste treatment. Phytoremediation is an alternative for extracting or trapping micropollutants from contaminated soils by mining residues. The potentialities of Chrysopogon zizanioides (acclimated plant) and Andropogon gayanus (native plant) to accumulate arsenic (As), mercury (Hg), iron (Fe) and zinc (Zn) were studied in artisanal gold mine in Ouagadougou, Burkina Faso. The phytoremediation effectiveness of two plant species was studied in 75 pots of 30 liters each, containing mining residues from the artisanal gold processing site in the rural commune of Nimbrogo. The experiments cover three modalities: Tn - planted unpolluted soils; To – unplanted mine tailings and Tp – planted mine tailings arranged in a randomized manner. The pots were amended quarterly with compost to provide nutrients to the plants. The phytoremediation assessment consists of comparing the growth, biomass and capacity of these two herbaceous plants to extract or to trap Hg, Fe, Zn and As in mining residues in a controlled environment. The analysis of plant species parameters cultivated in mine tailings shows indices of relative growth of A. gayanus very significantly high (34.38%) compared to 20.37% for C.zizanioides. While biomass analysis reveals that C. zizanioides has greater foliage and root system growth than A. gayanus. The results after a culture time of 6 months showed that C. zizanioides and A. gayanus have the potential to accumulate Hg, Fe, Zn and As. Root biomass has a more significant accumulation than aboveground biomass for both herbaceous species. Although the BCF bioaccumulation factor values for both plants together are low (<1), the removal efficiency of Hg, Fe, Zn and As is 45.13%, 42.26%, 21.5% and 2.87% respectively in 24 weeks of culture with C. zizanioides. However, pots grown with A. gayanus gives an effectiveness rate of 43.55%; 41.52%; 2.87% and 1.35% respectively for Fe, Zn, Hg and As. The results indicate that the plant species studied have a strong phytoremediation potential, although that of A. gayanus is relatively less than C. zizanioides.

Keywords: artisanal gold mine tailings, andropogon gayanus, chrysopogon zizanioides, phytoremediation

Procedia PDF Downloads 50
4734 The Investigation of Oil Price Shocks by Using a Dynamic Stochastic General Equilibrium: The Case of Iran

Authors: Bahram Fathi, Karim Alizadeh, Azam Mohammadbagheri

Abstract:

The aim of this paper is to investigate the role of oil price shocks in explaining business cycles in Iran using a dynamic stochastic general equilibrium approach. This model incorporates both productivity and oil revenue shocks. The results indicate that productivity shocks are relatively more important to business cycles than oil shocks. The model with two shocks produces different values for volatility, but these values have the same ranking as that of the actual data for most variables. In addition, the actual data are close to the ratio of standard deviations to the output obtained from the model with two shocks. The results indicate that productivity shocks are relatively more important to business cycles than the oil shocks. The model with only a productivity shock produces the most similar figures in term of volatility magnitude to that of the actual data. Next, we use the Impulse Response Functions (IRF) to evaluate the capability of the model. The IRF shows no effect of an oil shock on the capital stocks and on labor hours, which is a feature of the model. When the log-linearized system of equations is solved numerically, investment and labor hours were not found to be functions of the oil shock. This research recommends using different techniques to compare the model’s robustness. One method by which to do this is to have all decision variables as a function of the oil shock by inducing the stationary to the model differently. Another method is to impose a bond adjustment cost. This study intends to fill that gap. To achieve this objective, we derive a DSGE model that allows for the world oil price and productivity shocks. Second, we calibrate the model to the Iran economy. Next, we compare the moments from the theoretical model with both single and multiple shocks with that obtained from the actual data to see the extent to which business cycles in Iran can be explained by total oil revenue shock. Then, we use an impulse response function to evaluate the role of world oil price shocks. Finally, I present implications of the findings and interpretations in accordance with economic theory.

Keywords: oil price, shocks, dynamic stochastic general equilibrium, Iran

Procedia PDF Downloads 417
4733 Zinc Oxide Nanorods Decorated Nanofibers Based Flexible Electrodes for Capacitive Energy Storage Applications

Authors: Syed Kamran Sami, Saqib Siddiqui

Abstract:

In recent times, flexible supercapacitors retaining high electrochemical performance and steadiness along with mechanical endurance has developed as a spring of attraction due to the exponential progress and innovations in energy storage devices. To meet the rampant increasing demand of energy storage device with the small form factor, a unique, low cost and high-performance supercapacitor with considerably higher capacitance and mechanical robustness is required to recognize their real-life applications. Here in this report, synthesis route of electrode materials with low rigidity and high charge storage performance is reported using 1D-1D hybrid structure of zinc oxide (ZnO) nanorods, and conductive polymer smeared polyvinylidene fluoride–trifluoroethylene (P(VDF–TrFE)) electrospun nanofibers. The ZnO nanorods were uniformly grown on poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS) coated P(VDF-TrFE) nanofibers using hydrothermal growth to manufacture light weight, permeable electrodes for supercapacitor. The PEDOT: PSS coated P(VDF-TrFE) porous web of nanofibers act as framework with high surface area. The incorporation of ZnO nanorods further boost the specific capacitance by 59%. The symmetric device using the fabricated 1D-1D hybrid electrodes reveals fairly high areal capacitance of 1.22mF/cm² at a current density of 0.1 mA/cm² with a power density of more than 1600 W/Kg. Moreover, the fabricated electrodes show exceptional flexibility and high endurance with 90% and 76% specific capacitance retention after 1000 and 5000 cycles respectively signifying the astonishing mechanical durability and long-term stability. All the properties exhibited by the fabricated electrode make it convenient for making flexible energy storage devices with the low form factor.

Keywords: ZnO nanorods, electrospinning, mechanical endurance, flexible supercapacitor

Procedia PDF Downloads 269
4732 Rethinking Africa's 'Great Runner': Authoritarianism and Development in Post-Cold War Ethiopia

Authors: Frew Yirgalem Mane

Abstract:

This study has examined Africa’s experiment with authoritarian model of development drawing from the experience of Ethiopia. With the tectonic crisis of neoliberal ideology, the dominant policy agenda in Africa pertains to bringing the state back to development. More concretely, countries epitomized by Ethiopia, Rwanda and Uganda have been constructing a highly interventionist state with authoritarian character. The central motive appears to facilitate development and salvage people out of appalling and grinding poverty. Each country warrants closer inspection. However, this study focuses on Ethiopia- a country often applauded as ‘Africa’s Great Run’ for delivering socio-economic success over the past two decades. In fact, inspired by East Asia’s including Chinese model of authoritarian development, Ethiopia orchestrated a vanguard party, centralized rent control system with politicized bureaucracy and militaristic mobilization resources for development. This arrangement may explain Ethiopia economic success story as one the fastest growing countries in the world. However, this paper detected, Ethiopia’s attempt to bring the state back in development has precipitated institutionalization of a new breed of authoritarianism and informalization of public institutions. Ethiopia’s model of state-led development may constitute a noticeable shift away from the vengeful adherence to neoliberal policies. However, the manner the model has been practiced proved to be neither smooth nor appears to address Ethiopia’s aspiration for political and economic transformation. Partly, this can be illustrated by recent widespread grievances that fed into the popular uprising and animated opposition against the state. Sources of the grievance are complex, but they are highly ingrained with the way the authoritarian model of development is functioning and also the model’s dis-functioning in terms of benefiting people. In light of these findings, the study has arrived at the following conclusion. Africa’s attempt to emulate development models from other countries is not such a ‘bad’ thing. However, emulation makes sense if it is contextualized and sensitive to complex local socio-economic interests.

Keywords: Africa, authoritarianism, development, Ethiopia, neoliberalism

Procedia PDF Downloads 170
4731 Resilient Machine Learning in the Nuclear Industry: Crack Detection as a Case Study

Authors: Anita Khadka, Gregory Epiphaniou, Carsten Maple

Abstract:

There is a dramatic surge in the adoption of machine learning (ML) techniques in many areas, including the nuclear industry (such as fault diagnosis and fuel management in nuclear power plants), autonomous systems (including self-driving vehicles), space systems (space debris recovery, for example), medical surgery, network intrusion detection, malware detection, to name a few. With the application of learning methods in such diverse domains, artificial intelligence (AI) has become a part of everyday modern human life. To date, the predominant focus has been on developing underpinning ML algorithms that can improve accuracy, while factors such as resiliency and robustness of algorithms have been largely overlooked. If an adversarial attack is able to compromise the learning method or data, the consequences can be fatal, especially but not exclusively in safety-critical applications. In this paper, we present an in-depth analysis of five adversarial attacks and three defence methods on a crack detection ML model. Our analysis shows that it can be dangerous to adopt machine learning techniques in security-critical areas such as the nuclear industry without rigorous testing since they may be vulnerable to adversarial attacks. While common defence methods can effectively defend against different attacks, none of the three considered can provide protection against all five adversarial attacks analysed.

Keywords: adversarial machine learning, attacks, defences, nuclear industry, crack detection

Procedia PDF Downloads 139
4730 Strategies to Enhance Compliance of Health and Safety Standards at the Selected Mining Industries in Limpopo Province, South Africa: Occupational Health Nurse’s Perspective

Authors: Livhuwani Muthelo

Abstract:

The health and safety of the miners in the South African mining industry are guided by the regulations and standards which are anticipated to promote a healthy work environment and fatalities. It is of utmost importance for the miners to comply with these regulations/standards to protect themselves from potential occupational health and safety risks, accidents, and fatalities. The purpose of this study was to develop and validate strategies to enhance compliance with the Health and safety standards within the mining industries of Limpopo province in South Africa. A mixed-method exploratory sequential research design was adopted. The population consisted of 5350 miners. Purposive sampling was used to select the participants in the qualitative strand and stratified random sampling in the quantitative strand. Semi-structured interviews were conducted among the occupational health nurse practitioners and the health and safety team. Thematic analysis was used to generate an understanding of the interviews. In the quantitative strand, a survey was conducted using a self-administered questionnaire. Data were analysed using SPSS version 26.0. A descriptive statistical test was used in the analysis of data including frequencies, means, and standard deviation. Cronbach's alpha test was used to measure internal consistency. The integrated results revealed that there are diverse experiences related to health and safety standards compliance among the mineworkers. The main findings were challenges related to leadership compliance and also related to the cost of maintaining safety, Miner's behavior-related challenges; the impact of non-compliance on the overall health of the miners was also described, the conflict between production and safety. Health and safety compliance is not just mere compliance with regulations and standards but a culture that warrants the miners and organization to take responsibility for their behavior and actions towards health and safety. Thus taking responsibility for your well-being and other miners.

Keywords: perceptions, compliance, health and safety, legislation, standards, miners

Procedia PDF Downloads 86
4729 Different Orientations of Shape Memory Alloy Wire in Automotive Sector Product

Authors: Srishti Bhatt, Vaibhav Bhavsar, Adil Hussain, Aashay Mhaske, S. C. Bali, T. S. Srikanth

Abstract:

Shape Memory Alloys (SMA) are widely known for their unique shape recovery properties. SMA based actuation systems have high-force to weight ratio, light weight and also bio-compatible material. Which is why they are being used in different fields of aerospace, robotics, automotive and biomedical industries. However, in the automotive industry plenty of patents are available but commercially viable products are very few in market. This could be due to SMA material limitations like small stroke, direct dependability of lifecycle on stroke, pull load of the wire and high cycle time. In automotive sector, SMA being considered as an actuator which is required to have high stroke and constraint arises to accommodate a long length of wire (to compensate maximum 4 % strain as per better fatigue life cycle) not only increases complexity but also adds on the cost. More than 200 different types of actuators are used in an automobile, few of them whose efficiency can highly increase by replacing them with SMA based actuators which include latch lock mechanism, glove box, Head lamp leveling, side mirror and rear mirror leveling, tailgate opener and fuel lid cap actuator. To overcome the limitation of available space for required stroke of an actuator which leads to study the effect of different loading positions on SMA wires, different orientations of SMA wire by using pulleys and lever based systems to achieve maximum stroke. This investigation summarizes the loading under the V shape orientation the required stroke and carrying load capacity in more compact in comparison with straight orientation of wire. Similarly, the U shape orientation its showing higher load carrying capacity but reduced stroke which is aligned with concept of bundled wire method. Life-cycle of these orientations were also evaluated.

Keywords: actuators, automotive, nitinol, shape memory alloy, SMA wire orientations

Procedia PDF Downloads 71
4728 The Effect of PM10 Dispersion from Industrial, Residential and Commercial Areas in Arid Environment

Authors: Meshari Al-Harbi

Abstract:

A comparative area-season-elemental-wise time series analysis by Dust Track monitor (2012-2013) revealed high PM10 dispersion in the outdoor environment in the sequence of industrial> express highways>residential>open areas. Time series analysis from 7AM-6AM (until next day), 30d (monthly), 3600sec. (for any given period of a month), and 12 months (yearly) showed peak PM10 dispersion during 1AM-7AM, 1d-4d and 25d-31d of every month, 1500-3600 with the exception in PM10 dispersion in residential areas, and in the months-March to June, respectively. This time-bound PM10 dispersion suggests the primary influence of human activities (peak mobility and productivity period for a given time frame) besides the secondary influence of meteorological parameters (high temperature and wind action) and, occasional dust storms. Whereas, gravimetric analysis reveals the influence of precipitation, low temperature and low volatility resulting high trace metals in PM10 during winter than in summer and primarily attributes to the influence of nature besides, the secondary attributes of smoke stack emission from various industries and automobiles. Furthermore, our study recommends residents to limit outdoor air pollution exposures and take precautionary measures to inhale PM10 pollutants from the atmosphere.

Keywords: aerosol, pollution, respirable particulates, trace-metals

Procedia PDF Downloads 297
4727 Biofertilization of Cucumber (Cucumis sativus L.) Using Trichoderma longibrachiatum

Authors: Kehinde T. Kareem

Abstract:

The need to increase the production of cucumber has led to the use of inorganic fertilizers. This chemical affects the ecological balance of nature by increasing the nitrogen and phosphorus contents of the soil. Surface runoffs into rivers and streams cause eutrophication which affects aquatic organisms as well as the consumers of aquatic animals. Therefore, this study was carried out in the screenhouse to investigate the use of a plant growth-promoting fungus; Trichoderma longibrachiatum for the growth promotion of conventional and in-vitro propagated Ashley and Marketmoor cucumber. Before planting of cucumber, spore suspension (108 cfu/ml) of Trichoderma longibrachiatum grown on Potato dextrose agar (PDA) was inoculated into the soil. Fruits were evaluated for the presence of Trichoderma longibrachiatum using a species-specific primer. Results revealed that the highest significant plant height produced by in-vitro propagated Ashley was 19 cm while the highest plant height of in-vitro propagated Marketmoor was 19.67 cm. The yield of the conventional propagated Ashley cucumber showed that the number of fruit/plant obtained from T. longibrachiatum-fertilized plants were significantly more than those of the control. The in-vitro Ashely had 7 fruits/plant while the control produced 4 fruits/plant. In-vitro Marketmoor had ten fruits/plant, and the control had a value of 4 fruits/plant. There were no traces of Trichoderma longibrachiatum genes in the harvested cucumber fruits. Therefore, the use of Trichoderma longibrachiatum as a plant growth-promoter is safe for human health as well as the environment.

Keywords: biofertilizer, cucumber, genes, growth-promoter, in-vitro, propagation

Procedia PDF Downloads 222
4726 Genome-Wide Identification of Genes Resistance to Nitric Oxide in Vibrio parahaemolyticus

Authors: Yantao Li, Jun Zheng

Abstract:

Food poison caused by consumption of contaminated food, especially seafood, is one of most serious public health threats worldwide. Vibrio parahaemolyticus is emerging bacterial pathogen and the leading cause of human gastroenteritis associated with food poison, especially in the southern coastal region of China. To successfully cause disease in host, bacterial pathogens need to overcome the host-derived stresses encountered during infection. One of the toxic chemical species elaborated by the host is nitric oxide (NO). NO is generated by acidified nitrite in the stomach and by enzymes of the inducible NO synthase (iNOS) in the host cell, and is toxic to bacteria. Bacterial pathogens have evolved some mechanisms to battle with this toxic stress. Such mechanisms include genes to sense NO produced from immune system and activate others to detoxify NO toxicity, and genes to repair the damage caused by toxic reactive nitrogen species (RNS) generated during NO toxic stress. However, little is known about the NO resistance in V. parahaemolyticus. In this study, a transposon coupled with next generation sequencing (Tn-seq) technology will be utilized to identify genes for NO resistance in V. parahaemolyticus. Our strategy will include construction the saturating transposon insertion library, transposon library challenging with NO, next generation sequencing (NGS), bioinformatics analysis and verification of the identified genes in vitro and in vivo.

Keywords: vibrio parahaemolyticus, nitric oxide, tn-seq, virulence

Procedia PDF Downloads 253
4725 Rock-Bed Thermocline Storage: A Numerical Analysis of Granular Bed Behavior and Interaction with Storage Tank

Authors: Nahia H. Sassine, Frédéric-Victor Donzé, Arnaud Bruch, Barthélemy Harthong

Abstract:

Thermal Energy Storage (TES) systems are central elements of various types of power plants operated using renewable energy sources. Packed bed TES can be considered as a cost–effective solution in concentrated solar power plants (CSP). Such a device is made up of a tank filled with a granular bed through which heat-transfer fluid circulates. However, in such devices, the tank might be subjected to catastrophic failure induced by a mechanical phenomenon known as thermal ratcheting. Thermal stresses are accumulated during cycles of loading and unloading until the failure happens. For instance, when rocks are used as storage material, the tank wall expands more than the solid medium during charge process, a gap is created between the rocks and tank walls and the filler material settles down to fill it. During discharge, the tank contracts against the bed, resulting in thermal stresses that may exceed the wall tank yield stress and generate plastic deformation. This phenomenon is repeated over the cycles and the tank will be slowly ratcheted outward until it fails. This paper aims at studying the evolution of tank wall stresses over granular bed thermal cycles, taking into account both thermal and mechanical loads, with a numerical model based on the discrete element method (DEM). Simulations were performed to study two different thermal configurations: (i) the tank is heated homogeneously along its height or (ii) with a vertical gradient of temperature. Then, the resulting loading stresses applied on the tank are compared as well the response of the internal granular material. Besides the study of the influence of different thermal configurations on the storage tank response, other parameters are varied, such as the internal angle of friction of the granular material, the dispersion of particles diameters as well as the tank’s dimensions. Then, their influences on the kinematics of the granular bed submitted to thermal cycles are highlighted.

Keywords: discrete element method (DEM), thermal cycles, thermal energy storage, thermocline

Procedia PDF Downloads 393