Search results for: full Heusler structure

Authors: Ljubica Dokić, Ivana Nikolić, Dragana Šoronja–Simović, Zita Šereš, Biljana Pajin, Nils Juul, Nikola Maravić

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The possibility of application the dietary fibers in production of crackers was observed in this work, as well as their influence on rheological and textural properties on the dough for crackers and influence on sensory properties of obtained crackers. Three different dietary fibers, oat, potato and pea fibers, replaced 10% of wheat flour. Long fermentation process and baking test method were used for crackers production. The changes of dough for crackers were observed by rheological methods of determination the viscoelastic dough properties and by textural measurements. Sensory quality of obtained crackers was described using quantity descriptive method (QDA) by trained members of descriptive panel. Additional analysis of crackers surface was performed by videometer. Based on rheological determination, viscoelastic properties of dough for crackers were reduced by application of dietary fibers. Manipulation of dough with 10% of potato fiber was disabled, thus the recipe modification included increase in water content at 35%. Dough compliance to constant stress for samples with dietary fibers decreased, due to more rigid and stiffer dough consistency compared to control sample. Also, hardness of dough for these samples increased and dough extensibility decreased. Sensory properties of final products, crackers, were reduced compared to control sample. Application of dietary fibers affected mostly hardness, structure and crispness of the crackers. Observed crackers were low marked for flavor and taste, due to influence of fibers specific aroma. The sample with 10% of potato fibers and increased water content was the most adaptable to applied stresses and to production process. Also this sample was close to control sample without dietary fibers by evaluation of sensory properties and by results of videometer method.

Keywords: crackers, dietary fibers, rheology, sensory properties

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Authors: Maryam Jaberi, Siavosh Shayan, Mojtaba Yamani

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Habble-Rud River basin (HR), up to 100 km length, one of the largest watersheds which drain into deserts to the north of Central Iran (Dasht-e Kavir). This stream is oblique with the NE-SW trending, flow in the southern range of central Alborz Mountains and the northern border of Central Iran. The end of the ~17 km suddenly change direction and with the southern trending to have a morphology which meanders passes through the Alborz Mountain ridge and flows into the Garmsar plain where it forms one of the largest alluvial fans in Iran, i.e. the vast Garmsar alluvial fan with an area of 476 km2. This study was carried out through morphometric analyses, longitudinal river profiles, and study of geomorpholic evidence such as fluvial terraces, gypsum-salt domes, seismic data, and satellite images. This study aimed to investigate the changes in the pattern of rivers in the southern part of the HR river basin. The southern part of HR river basin located at the southern foothills of the Central Alborz is characterized the thrust faults (Sorkheh-Kalut and Garmsar faults), folds,diapirs and arid climate. The activity of more than 10 salt domes that belong to the Oligocene-Miocene period has considerably influenced the pattern of streams in this region. Dissolution of these domes has not only reduced the quality of water and soil resources, but also has led to the formation of badlands and gullies.Our results indicated that the pattern of rivers in the southern part of HR river basin was influenced by discharge of the HR river in Quaternary, geological structure, subsidence of Central Iran and vertical uplift of Alborz mountain. These agents caused the formation meanders in the southern part of the HR River and evaluation of the seasonal rivers like Shoor-Darre and Garmabsar.

Keywords: geomorphologic evaluation, rivers pattern, Habble-Rud River basin, seasonal rivers

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Authors: Karen G. Bastidas Gomez, Hugo R. Zea Ramirez, Manuel F. Ribeiro Pereira, Cesar A. Sierra Avila, Juan A. Clavijo Morales

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The contamination of water sources with heavy metals such as mercury has been an environmental problem; it has generated a high impact on the environment and human health. In countries such as Colombia, mercury contamination due to mining has reached levels much higher than the world average. This work proposes the use of fique fibers as adsorbent in mercury removal. The evaluation of the material was carried out under five different conditions (raw, pretreated by organosolv, functionalized by TEMPO oxidation, fiber functionalized plus MOF-199 and fiber functionalized plus MOF-199-SH). All the materials were characterized using FTIR, SEM, EDX, XRD, and TGA. Regarding the mercury removal, it was done under room pressure and temperature, also pH = 7 for all materials presentations, followed by Atomic Absorption Spectroscopy. The high cellulose content in fique is the main particularity of this lignocellulosic biomass since the degree of oxidation depends on the number of hydroxyl groups on the surface capable of oxidizing into carboxylic acids, a functional group capable of increasing ion exchange with mercury in solution. It was also expected that the impregnation of the MOF would increase the mercury removal; however, it was found that the functionalized fique achieved a greater percentage of removal, resulting in 81.33% of removal, 44% for the fique with the MOF-199 and 72% for the MOF-199-SH with. The pretreated fiber and raw also showed 74% and 56%, respectively, which indicates that fique does not require considerable modifications in its structure to achieve good performances. Even so, the functionalized fiber increases the percentage of removal considerably compared to the pretreated fique, which suggests that the functionalization process is a feasible procedure to apply with the purpose of improving the removal percentage. In addition, this is a procedure that follows a green approach since the reagents involved have low environmental impact, and the contribution to the remediation of natural resources is high.

Keywords: biomass, nanotechnology, science materials, wastewater treatment

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Authors: Usama Bin Zubair, Syed Azhar Ali

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Introduction: Depression is emerging as a major public health problem in all parts of the world. Developing countries have a unique socioeconomic structure that affects the lives of its inhabitants in several ways. Going abroad for employment is one of the common social problems which have been faced by young males in developing countries. This included both highly qualified individuals as well as the labor class. Objective: To determine the difference in the presence of depressive symptoms among pregnant women with husbands living abroad and those with husbands living with them in Azad Jammu and Kashmir. Methods: The sample population comprised of pregnant women reporting for an antenatal checkup at Amna hospital Rawalakot. Cases constituted the pregnant women with husbands living abroad while controls were the pregnant women with husbands living with them. Patient health questionnaire-9 (PHQ-9) was used to record the presence and severity of depressive symptoms. Age, gestation, parity, rural or urban origin, education, level of family income, daily contact hours on the telephone or what’s app, previous pregnancy loss or complications, number of years abroad and visits to home per year were associated with the presence of depressive symptoms. Findings: The mean age of the study participants was 29.73 ±5.395 years. Sixty-six had significant depression in the case group, while 14 had in the control group (p-value<0.001). Education and rural background had a significant difference between the case and the control group. Less number of visits per year of the husband was strongly linked with the presence of depressive symptoms among the cases. Conclusion: Pregnant women with husbands abroad were found more prone to develop depressive symptoms as compared to those with husbands living with them. Special attention should be paid to the women whose husband had a lesser number of visits to the country.

Keywords: depression, pregnancy, lack of support, war zone

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Authors: Mannar R. Maurya, Bhawna Uprety, Fernando Avecilla, Pedro Adão, J. Costa Pessoa

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The reaction of the tripodal tetradentate dibasic ligand 6,6'–(2–(pyridin–2–yl)ethylazanediyl)bis(methylene)bis(2,4–di–tert–butylphenol), H2L1 I, with [VIVO(acac)2] in CH3CN gives the VVO–complex, [VVO(acac)(L1)] 1. Crystallization of 1 in CH3CN at ~0 ºC, gives dark blue crystals of 1, while at room temperature it affords dark green crystals of [{VVO(L1)}2µ–O] 3. Upon prolonged treatment of 1 in MeOH [VVO(OMe)(MeOH)(L1)] 2 is obtained. All three complexes are analyzed by single–crystal X–ray diffraction, depicting distorted octahedral geometry around vanadium. In the reaction of H2L1 with VIVOSO4 partial hydrolysis of the tripodal ligand results in elimination of the pyridyl fragment of L1 and the formation of H[VVO2(L2)] 4, containing the ONO tridentate ligand 6,6'–azanediylbis(methylene)bis(2,4–di–tert–butylphenol), H2L2 II. Compound 4, which was not fully characterized, undergoes dimerization in acetone yielding the hydroxido–bridged [{VVO(L2)}2µ–(HO)2] 5, having distorted octahedral geometry around each vanadium. In contrast, from a solution of 4 in acetonitrile, the dinuclear compound [{VVO(L2)}2µ–O] 6 is obtained, with trigonal bipyramidal geometry around each vanadium. The methoxido complex 2 is successfully employed as a functional catechol–oxidase mimic in the oxidation of catechol to o–quinone under air. The process is confirmed to follow a Michaelis–Menten type kinetics with respect to catechol, the Vmax and KM values obtained being 7.66×10–6 M min -1 and 0.0557 M, respectively, and the turnover frequency is 0.0541 min–1. Complex 2 is also used as a catalyst precursor for the oxidative bromination of thymol in aqueous medium. The selectivity shows quite interesting trends, namely when not using excess of primary oxidizing agent, H2O2 the para mono–brominated product corresponds to ~93 % of the products and no dibromo derivative is formed.

Keywords: oxidovanadium (V) complexes, tripodal ligand, crystal structure, catechol oxidase mimetic activity

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Authors: Adya Uluwita, Fernando Pedrosa, Georgi Georgiev, Christian Bernard, Raoul Masterson

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CERN is an international organisation funded by 23 countries that provide the particle physics community with excellence in particle accelerators and other related facilities. Founded in 1954, CERN has a wide range of accelerators that allow groundbreaking science to be conducted. Accelerators bring particles to high levels of energy and make them collide with each other or with fixed targets, creating specific conditions that are of high interest to physicists. A chain of accelerators is used to ramp up the energy of particles and eventually inject them into the largest and most recent one: the Large Hadron Collider (LHC). Among this chain of machines is, for instance the Proton Synchrotron, which was started in 1959 and is still in operation. These machines, called "injectors”, keep evolving over time, as well as the related infrastructure. Massive decommissioning of obsolete cables started in 2015 at CERN in the frame of the so-called "injectors de-cabling project phase 1". Its goal was to replace aging cables and remove unused ones, freeing space for new cables necessary for upgrades and consolidation campaigns. To proceed with the de-cabling, a project co-ordination team was assembled. The start of this project led to the investigation of legacy cables throughout the organisation. The identification of cables stacked over half a century proved to be arduous. Phase 1 of the injectors de-cabling was implemented for 3 years with success after overcoming some difficulties. Phase 2, started 3 years later, focused on improving safety and structure with the introduction of a quality assurance procedure. This paper discusses the implementation of this quality assurance procedure throughout phase 2 of the project and the transition between the two phases. Over hundreds of kilometres of cable were removed in the injectors complex at CERN from 2015 to 2023.

Keywords: CERN, de-cabling, injectors, quality assurance procedure

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Authors: Barbara Pittau, Piergiorgio Palla, Antonio Mastino

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Communication is fundamental to health education. The proper use of medicinal products is a crucial aspect of the health of citizens that affects both safety and health care spending. Therefore, encouraging/promoting communication, concerning the importance of proper use of pharmaceuticals, has substantial implications in terms of individual health, health care, and health care system sustainability. In view of these considerations, in the context of two projects, one of which is still in progress, a relational database-backed web application named COLLABORAFARMACISOLA has been designed and developed as a tool to analyze and visualize how people approach the use of medicinal products, with the aim of improving and enhancing communication efficacy. The software application is being used to collect information (anonymously and voluntarily) from the citizens of Sardinia, an Italian region, regarding their knowledge, experiences, and opinions towards pharmaceuticals. This study that was conducted to date on thousand of interviewed people, has focused on different aspects such as: the treatment interruption and the "self-prescription” without medical consultation, the attention paid to reading the leaflets, the awareness of the economic value of the pharmaceuticals, the importance of avoiding the waste of medicinal products and the attitudes towards the use of generics. To this purpose, our software application provides a set of ad hoc parsing routines, to store information into the structure of a relational database and to process and visualize it through a set of interactive tools aimed to emphasize the findings and the insights obtained. The results of our preliminary analysis show the efficacy of the awareness plan and, at the same time, the criticality and the needs of the territory under examination. The ultimate goal of our study is to provide a contribution to the community by improving communication that can result in a benefit for public health in a context strictly connected to the reality of the territory.

Keywords: communication, pharmaceuticals, public health, relational database, tool, web application

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Authors: José Alberto García Fernández, Zhimin Du, Xinqiao Jin

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Nowadays, data center industry faces strong challenges for increasing the speed and data processing capacities while at the same time is trying to keep their devices a suitable working temperature without penalizing that capacity. Consequently, the cooling systems of this kind of facilities use a large amount of energy to dissipate the heat generated inside the servers, and developing new cooling techniques or perfecting those already existing would be a great advance in this type of industry. The installation of a temperature sensor matrix distributed in the structure of each server would provide the necessary information for collecting the required data for obtaining a temperature profile instantly inside them. However, the number of temperature probes required to obtain the temperature profiles with sufficient accuracy is very high and expensive. Therefore, other less intrusive techniques are employed where each point that characterizes the server temperature profile is obtained by solving differential equations through simulation methods, simplifying data collection techniques but increasing the time to obtain results. In order to reduce these calculation times, complicated and slow computational fluid dynamics simulations are replaced by simpler and faster finite element method simulations which solve the Burgers‘ equations by backward, forward and central discretization techniques after simplifying the energy and enthalpy conservation differential equations. The discretization methods employed for solving the first and second order derivatives of the obtained Burgers‘ equation after these simplifications are the key for obtaining results with greater or lesser accuracy regardless of the characteristic truncation error.

Keywords: Burgers' equations, CFD simulation, data center, discretization methods, FEM simulation, temperature profile

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Authors: Jelena Maletkovic

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Background: Endogenous Cushing’s syndrome is a rare disease, but iatrogenic or drug related Cushing syndrome from glucocorticoid products is commonly seen in clinical practice. With high dose and long term use of glucocorticoids, patients can develop isolated hypothalamic-pituitary-adrenal (HPA) suppression, or HPA axis suppression can be accompanied by overt iatrogenic Cushing’s syndrome. This is a rare case where severe Cushing’s syndrome developed from an unknown medication and was followed by severe and prolonged adrenal insufficiency and multiple potentially fatal complications. Case: This is a 37-year-old woman who is presented to Emergency Room (ER) with shortness of breath and chest pain. Four months prior to this presentation the patient was a generally healthy woman who was looking for improvement in her appearance and visited local Rejuvenation Clinic. After initial consultation with a nurse, she was contacted by a physician over the phone and was advised to start taking multiple injectable medications that will arrive by mail. Medications without any labels on bottles were delivered and the patient started daily intramuscular injections. Over the next two months, she noticed rounding of her face and swelling around her eyes. She gained 20 pounds, mostly abdominal fat and became extremely fatigued. Her muscles on legs were visibly decreasing in size and she felt significant muscle weakness. Unexplained bruising occurred. She started growing hair on face and developed secondary amenorrhea. New severe back pain started. She developed depression and headaches. Finally, over a few days, a number of red-purple stretch marks that were sensitive and painful appeared over her abdomen, upper part of arms and legs. She then became suspicious that these dramatic symptoms are caused by injectable medication and she discontinued injections. Over the next few days she presented to ER with low blood pressure and oxygen saturation of 75%. Studies revealed extensive pneumonia as well as multiple pulmonary emboli. Her white blood count was elevated with 32 000 and she also had acute kidney failure on admission. She was treated for sepsis and was also given stress dose steroids. Steroids were tapered over 48 hours and discontinued. After being discharged to home, on her first visit to endocrinology clinic she had undetectable ACTH of < 2pg/mL and undetectable 8am cortisol of < 0.2mcg/dL. She did not respond to an intramuscular injection of cosyntropin 250mcg and her repeated cortisol after 60 minutes was only 1mcg/dL. The patient was diagnosed with adrenal insufficiency and was started on hydrocortisone 20mg+10mg. It took close to 2 years of slow tapering for recovery of this patient’s HPA axis and resolve all the sequelae from Cushing’s syndrome. Conclusion: Misuse and abuse of glucocorticoids have been present almost since these medications were discovered. This is a rare case where not only severe Cushing’s syndrome in full clinical picture developed but also the patient suffered multiple potentially fatal complications and prolonged adrenal insufficiency. Visits to herbal, rejuvenation, esthetic, and similar clinics are becoming more and more popular and physicians need to be aware of possible non-benign nature of medications that their patients may be using.

Keywords: iatrogenic, Cushing's syndrome, adrenal crisis, steroid abuse

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Authors: Lize Tibiriçá, Ronnie Lee, Samantha Behbahani

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Fibromyalgia (FM) is a musculoskeletal disorder affecting men and women of different ages and cultures. The cause of this disorder is unknown; however, studies suggest an etiology that involves biological and psychosocial factors. Few studies have shown that a personality type such as neuroticism is associated with chronic pain conditions. Past research has explored whether patients with FM present with a specific personality trait. However, studies have used different methods (i.e. Minnesota Multiphasic Personality Inventory (MMPI), Sociotropy and Autonomy Scale (SAS) and Dysfunctional Attitude Scale (DAS), Tridimensional Personality Questionnaire or Temperament and Character Inventory (TCI), Karolinska scale of personality, Big Five Inventory or NEO Personality Inventory) to explore the connection between FM and a personality type. They have identified personality types that present similar characteristics but vary in the name (i.e. high harm avoidance and low novelty seeking, psychasthenia/muscular tension/somatic anxiety, neuroticism). Although Zuckerman-Kuhlman Personality Questionnaire and the Big Five Inventory differ in terms of content and structure, both of them identify neuroticism as the personality type of FM patients, and the former also identifies these patients as having a low sociability personality trait. Previous research also shows a trend of sociotropic personality style with FM patients that also suffer from Major Depressive Disorder. Participants in these studies were, for the most part, adult female and researchers have recognized that as a limitation and whether their findings can be generalized to men and younger patients with FM. Furthermore, most studies reviewed were conducted in Europe (i.e. Spain) and had a cross-sectional design. Future research should replicate past studies in different countries and consider conducting a longitudinal study. Although it is suspected that FM course is modulated by FM patients’ personality, it is not known whether individuals with similar personalities will develop FM. This review sought to explain the differences and similarities between the personality types identified. Limitations in the studies reviewed were addressed, and considerations for future research and treatment were discussed.

Keywords: chronic pain, fibromyalgia, neuroticism, personality type

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Authors: Yasir Arafat, Asma Shah, Hua Shao

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Background and Aims: Legume/cereal intercropping is used worldwide for enhancement in biomass and yield of cereal crops. However, because of intercropping, the belowground biological and chemical interactions and their effect on physiological parameters and yield of crops are limited. Methods: Wheat faba bean (WF) intercropping was designed to understand the underlying changes in the soil's chemical environment, soil microbial communities, and effect on growth and yield parameters. Experimental plots were established as having no root partition (NRP), semi-root partition (SRP), complete root partition (CRP), and their sole cropping (CK). Low molecular weight organic acids (LMWOAs) were determined by GC-MS, and high throughput sequencing of the 16S rRNA gene was carried out to screen microbial structure and composition in different root partitions of the WF intercropping system. Results: We show that intercropping induced a shift in the relative abundance of some genera of plant growth promoting rhizobacteria (PGPR) such as Allorhizobium, Neorhizobium, Pararhizobium, and Rhizobium species and resulted in better growth and yield performance of wheat. Moreover, as the plant's distance of wheat from faba beans decreased, the diversity of microbes increased, and a positive effect was observed on physiological traits and crop yield. Furthermore, an abundance and positive correlations of palmitic acid, arachidic acid, stearic acid, and 9-Octadecenoic with PGPR were recorded in the root zone of WF intercropping, which can play an important role in this facilitative mechanism of enhancing growth and yield of cereals. Conclusion: The two treatments clearly affected soil microbial and chemical composition, which can be reflected in growth and yield enhancement.

Keywords: intercropping, microbial community, LMWOAs, PGPR, soil chemical environment

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Authors: Jawaher A. Alsultan, Allen Feldman

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With the rapid switch to remote learning due to the COVID-19 pandemic, science teachers were suddenly required to teach their classes online. This breakneck shift to eLearning raised the question of how teacher educators could support science teachers who wanted to use reform-based methods of instruction while using virtual technologies. In this retrospective self-study, we, two science teacher educators, examined our practice as we worked with science teachers to implement inquiry, discussion, and argumentation [IDA] through eLearning. Ten high school science teachers from a large school district in the southeastern US participated virtually in the COVID-19 Community of Practice [COVID-19 CoP]. The CoP met six times from the end of April through May 2020 via Zoom. Its structure was based on a model of action research called enhanced normal practice [ENP], which includes exchanging stories, trying out ideas, and systematic inquiry. Data sources included teacher educators' meeting notes and reflective conversations, audio recordings of the CoP meetings, teachers' products, and post-interviews of the teachers. Findings included a new understanding of the role of existing relationships, shared goals, and similarities in the participants' situations, which helped build trust in the CoP, and the effects of our paying attention to the science teachers’ needs led to a well-functioning CoP. In addition, we became aware of the gaps in our knowledge of how the teachers already used apps in their practice, which they then shared with all of us about how they could be used for online teaching using IDA. We also identified the need to pay attention to feelings about tensions between the teachers and us around the expectations for final products and the project's primary goals. We found that if we are to establish relationships between us as facilitators and teachers that are honest, fair, and kind, we must express those feelings within the collective, dialogical processes that can lead to learning by all members of the CoP, whether virtual or face-to-face.

Keywords: community of practice, facilitators, self-study, action research

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Authors: Hang Yang, Jichao Li, Kewei Yang, Tianyang Lei

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Multivariate time series anomaly detection is a significant research topic in the field of data mining, encompassing a wide range of applications across various industrial sectors such as traffic roads, financial logistics, and corporate production. The inherent spatial dependencies and temporal characteristics present in multivariate time series introduce challenges to the anomaly detection task. Previous studies have typically been based on the assumption that all variables belong to the same spatial hierarchy, neglecting the multi-level spatial relationships. To address this challenge, this paper proposes a multi-scale spatial and unified temporal feature fusion network, denoted as MSUT-Net, for multivariate time series anomaly detection. The proposed model employs a multi-level modeling approach, incorporating both temporal and spatial modules. The spatial module is designed to capture the spatial characteristics of multivariate time series data, utilizing an adaptive graph structure learning model to identify the multi-level spatial relationships between data variables and their attributes. The temporal module consists of a unified temporal processing module, which is tasked with capturing the temporal features of multivariate time series. This module is capable of simultaneously identifying temporal dependencies among different variables. Extensive testing on multiple publicly available datasets confirms that MSUT-Net achieves superior performance on the majority of datasets. Our method is able to model and accurately detect systems data with multi-level spatial relationships from a spatial-temporal perspective, providing a novel perspective for anomaly detection analysis.

Keywords: data mining, industrial system, multivariate time series, anomaly detection

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Authors: M. A. Bayona, E. M. Cordoba, V. R. Guiza

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Highly porous carbon-based foams are used in a wide range of industrial applications, which include absorption, catalyst supports, thermal insulation, and biomaterials, among others. Particularly, silicon carbide (SiC) based foams have shown exceptional potential for catalyst support applications, due to their chemical inertness, large frontal area, low resistance to flow, low-pressure drop, as well as high resistance to temperature and corrosion. These properties allow the use of SiC foams in harsh environments with high durability. Commonly, SiC foams are fabricated from polysiloxane, SiC powders and phenolic resins, which can be costly or highly toxic to the environment. In this work, we propose a low-cost method for the fabrication of highly porous, three-dimensional SiC foams via template replica, using recycled polymeric sponges as sacrificial templates. A sucrose-based resin combined with a Si-containing pre-ceramic polymer was used as the precursor. Polymeric templates were impregnated with the precursor solution, followed by thermal treatment at 1500 °C under an inert atmosphere. Several synthesis parameters, such as viscosity and composition of the precursor solution (Si: Sucrose molar ratio), and the porosity of the template, were evaluated in terms of their effect on the morphology, composition and mechanical resistance of the resulting SiC foams. The synthesized composite foams exhibited a highly porous (50-90%) and interconnected structure, containing 30-90% SiC with a mechanical compressive strength between 0.01-0.1 MPa. The methodology employed here allowed the fabrication of foams with a varied concentration of SiC and with morphological and mechanical properties that contribute to the development of materials of high relevance in the industry, while using low-cost, renewable sources such as table sugar, and providing a recycling alternative for polymeric sponges.

Keywords: catalyst support, polymer replica technique, reticulated porous ceramics, silicon carbide

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Authors: Jose Ramon Sanabria Navarro, Yahilina Silveira Perez

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The Pan American Games are one of the best regional sports integration events for the Americas, thousands of athletes from different countries are integrated based on obtaining satisfactory sports results and bringing the glory of the national identity of the sport to their country. There are countries that despite the small number of inhabitants have obtained very satisfactory results such as Cuba. Objective: To analyze the impact of Cuba's sports results in the Pan American Games. The methodology was based on the postulates of the materialist dialectic since the investigated reality was studied from historicity, systematicity and in its systemic character. The population and sample consisted of 41 countries of the American continent, and the 15 events carried out to date were analyzed. The impact of Cuba is very relevant because it is the country that has the second place by country in terms of number of medals, is among the first in terms of medals per inhabitants and in general sense of all the indicators treated assumes the fourth place integral. What is the current status of Cuba's sports results in Pan American Games? Having as a general objective, analyze the impact of Cuba's sports results in the Pan American Games. The hypotheses that will lead this research have the following methodological and interaction order: H1: Cuba's performance in Pan American Sports Games positively impacts the amount of medals obtained. H2: The amount of medals from Cuba in Pan American Sports Games positively impacts the general podium for countries of these regional events. H3: The amount of medals obtained by Cuba in Pan American Sports Games positively impacts the number of inhabitants. H4: The amount of medals obtained by Cuba positively impacts the overall result of the countries. H5: Cuba's performance in the Panamerican Sports Games positively impacts the overall results of these regional events. In general, it is possible to demonstrate the impact of Cuba's sports performance in Pan American Games and the organizational sports structure that has allowed the country to obtain them is evidenced.

Keywords: Cuba, history of sport, sports games, regional events, sport

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Authors: Rishi Kanth Saripalle

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Medical experts highly recommend to include physical activity in everyone’s daily routine irrespective of gender or age as it helps to improve various medical issues or curb potential issues. Simultaneously, experts are also diligently trying to provide various healthcare services (interventions, plans, exercise routines, etc.) for promoting healthy living and increasing physical activity in one’s ever increasing hectic schedules. With the introduction of wearables, individuals are able to keep track, analyze, and visualize their daily physical activities. However, there seems to be no common agreed standard for representing, gathering, aggregating and analyzing an individual’s physical activity data from disparate multiple sources (exercise pans, multiple wearables, etc.). This issue makes it highly impractical to develop any data-driven physical activity applications and healthcare programs. Further, the inability to integrate the physical activity data into an individual’s Electronic Health Record to provide a wholistic image of that individual’s health is still eluding the experts. This article has identified three primary reasons for this potential issue. First, there is no agreed standard, both structure and semantic, for representing and sharing physical activity data across disparate systems. Second, various organizations (e.g., LA fitness, Gold’s Gym, etc.) and research backed interventions and programs still primarily rely on paper or unstructured format (such as text or notes) to keep track of the data generated from physical activities. Finally, most of the wearable devices operate in silos. This article identifies the underlying problem, explores the idea of reusing existing standards, and identifies the essential modules required to move forward.

Keywords: electronic physical activity record, physical activity in EHR EIM, tracking physical activity data, physical activity data standards

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Authors: Maali-Amel Mersel, Lajos Fodor, Otto Horvath

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Photocatalytic H₂ production by H₂S decomposition is regarded to be an environmentally friendly process to produce carbon-free energy through direct solar energy conversion. For this purpose, sulphide-based materials, as photocatalysts, were widely used due to their excellent solar spectrum responses and high photocatalytic activity. The loading of proper co-catalysts that are based on cheap and earth-abundant materials on those semiconductors was shown to play an important role in the improvement of their efficiency. In this research, CdS-ZnS composite was studied because of its controllable band gap and excellent performance for H₂ evolution under visible light irradiation. The effects of the modification of this photocatalyst with different types of materials and the influence of the preparation parameters on its H₂ production activity were investigated. The CdS-ZnS composite with an enhanced photocatalytic activity for H₂ production was synthesized from ammine complexes. Two types of modification were used: compounds of Ni-group metals (NiS, PdS, and Pt) were applied as co-catalyst on the surface of CdS-ZnS semiconductor, while NiS, MnS, CoS, Ag₂S, and CuS were used as a dopant in the bulk of the catalyst. It was found that 0.1% of noble metals didn’t remarkably influence the photocatalytic activity, while the modification with 0.5% of NiS was shown to be more efficient in the bulk than on the surface. The modification with other types of metals results in a decrease of the rate of H₂ production, while the co-doping seems to be more promising. The preparation parameters (such as the amount of ammonia to form the ammine complexes, the order of the preparation steps together with the hydrothermal treatment) were also found to highly influence the rate of H₂ production. SEM, EDS and DRS analyses were made to reveal the structure of the most efficient photocatalysts. Moreover, the detection of the conduction band electron on the surface of the catalyst was also investigated. The excellent photoactivity of the CdS-ZnS catalysts with and without modification encourages further investigations to enhance the hydrogen generation by optimization of the reaction conditions.

Keywords: H₂S, photoactivity, photocatalytic H₂ production, CdS-ZnS

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Authors: Felix Eyben, Simon Schaffrath, Markus Feldmann

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A building should maximize the potential for use through its design. Therefore, flexible use is always important when designing a steel structure. To create flexibility, steel beams with web openings are increasingly used, because these offer the advantage that cables, pipes and other technical equipment can easily be routed through without detours, allowing for more space-saving and aesthetically pleasing construction. This can also significantly reduce the height of ceiling systems. Until now, beams with web openings were not explicitly considered in the European standard. However, this is to be done with the new EN 1993-1-13, in which design rules for different opening forms are defined. In order to further develop the design concepts, beams with web openings under bending are therefore to be investigated in terms of damage mechanics as part of a German national research project aiming to optimize the verifications for steel structures based on a wider database and a validated damage prediction. For this purpose, first, fundamental factors influencing the load-bearing behavior of girders with web openings under bending load were investigated numerically without taking material damage into account. Various parameter studies were carried out for this purpose. For example, the factors under study were the opening shape, size and position as well as structural aspects as the span length, arrangement of stiffeners and loading situation. The load-bearing behavior is evaluated using resulting load-deformation curves. These results are compared with the design rules and critically analyzed. Experimental tests are also planned based on these results. Moreover, the implementation of damage mechanics in the form of the modified Bai-Wierzbicki model was examined. After the experimental tests will have been carried out, the numerical models are validated and further influencing factors will be investigated on the basis of parametric studies.

Keywords: damage mechanics, finite element, steel structures, web openings

Procedia PDF Downloads 173

Authors: Akriti Chandra, Gourav Dwivedi, Seema Sharma, Shivani

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This study investigates the adoption of green business (GB) models within a circular economy framework (CEBM) for Micro Small and Medium Enterprise (MSME), given the rising importance of sustainable practices. The research begins by exploring the shift from linear business models towards resource-efficient, sustainable models, emphasizing the benefits of the circular economy. The study's literature review identifies 60 influential factors impacting the shift to green businesses, grouped as internal and external drivers. However, there is a research gap in examining these factors' interrelationships and operationalizing them within MSMEs. To address this gap, the study employs Total Interpretive Structural Modelling (TISM) to establish a hierarchical structure of factors influencing GB and circular economy business model (CEBM) adoption. Findings reveal that factors like green innovation and market competitiveness are particularly impactful. Using Systems Theory, which views organizations as complex adaptive systems, the study contextualizes these drivers within MSMEs, proposing a framework for a sustainable business model adoption. The study concludes with significant implications for policymakers, suggesting that the identified factors and their hierarchical relationships can guide policy formulation for a broader transition to green business practices. This work also invites further research, recommending larger, quantitative studies to empirically validate these factors and explore practical challenges in implementing CEBMs.

Keywords: green business (GB), circular economy business model (CEBM), micro small and medium enterprise (MSME), total interpretive structural modelling (TISM), systems theory

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Authors: Latha Krishnan, Andrew Cobley

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Epoxy resin is most widely used as matrices for composites of aerospace, automotive and electronic applications due to its outstanding mechanical properties. These properties are chiefly predetermined by the chemical structure of the prepolymer and type of hardener but can also be varied by the processing conditions such as prepolymer and hardener mixing, degassing and curing conditions. In this research, the effect of degassing on the curing behaviour and the void occurrence is experimentally evaluated for epoxy /anhydride resin system. The epoxy prepolymer was mixed with an anhydride hardener and accelerator in an appropriate quantity. In order to investigate the effect of degassing on the curing behaviour and void content of the resin, the uncured resin samples were prepared using three different methods: 1) no degassing 2) degassing on prepolymer and 3) degassing on mixed solution of prepolymer and hardener with an accelerator. The uncured resins were tested in differential scanning calorimeter (DSC) to observe the changes in curing behaviour of the above three resin samples by analysing factors such as gel temperature, peak cure temperature and heat of reaction/heat flow in curing. Additionally, the completely cured samples were tested in DSC to identify the changes in the glass transition temperature (Tg) between the three samples. In order to evaluate the effect of degassing on the void content and morphology changes in the cured epoxy resin, the fractured surfaces of cured epoxy resin were examined under the scanning electron microscope (SEM). Also, the changes in the mechanical properties of the cured resin were studied by three-point bending test. It was found that degassing at different stages of resin mixing had significant effects on properties such as glass transition temperature, the void content and void size of the epoxy/anhydride resin system. For example, degassing (vacuum applied on the mixed resin) has shown higher glass transition temperature (Tg) with lower void content.

Keywords: anhydride epoxy, curing behaviour, degassing, void occurrence

Procedia PDF Downloads 346

Authors: Elisabeth Pedersen

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Representations and interpretations of womanhood and female sexualities bring forth various questions regarding gender norms, and the implications of these norms, which are permeating and repetitive within various societies. Literature is one form of media which provides the space to represent and interpret women, their bodies, and sexualities, and also reveals the power of language as an affective and affected force. As literature allows an opportunity to explore history and the representations of gender, power dynamics, and sexuality through historical contexts, this paper uses engaged theory through a comparative analysis of two work of literature, The Duchess of Malfi by John Wester, and The Sound and the Fury by William Faulkner. These novels span across space and time, which lends to the theory that repetitive tropes of womanhood and female sexuality in literature are influenced by and have an influence on the hegemonic social order throughout history. It analyzes how the representation of the dichotomy of male chivalry and honor, and female purity are disputed and questioned when a woman is portrayed as sexually emancipated, and explores the historical context in which these works were written to examine how socioeconomic events challenged the hegemonic social order. The analysis looks at how stereotypical ideals of womanhood and manhood have damaging implications on women, as the structure of society provides more privilege and power to men than to women, thus creating a double standard for men and women in regards to sexuality, sexual expression, and rights to sexual desire. This comparative analysis reveals how strict gender norms are permeating and have negative consequences. However, re-reading stories through a critical lens can provide an opportunity to challenge the repetitive tropes of female sexuality, and thus lead to the embrace of the complexity of female sexuality and expression.

Keywords: femininity, literature, representation, sexuality

Procedia PDF Downloads 358

Authors: Yahya Al-Wahaibi, Saif Al-Bahry, Abdulkadir Elshafie, Ali Al-Bemani, Sanket Joshi

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Microbial enhanced oil recovery is one of the most economical and efficient methods for extending the life of production wells in a declining reservoir. There are a variety of metabolites produced by microorganisms that can be useful for oil recovery, like biopolymers-polysaccharides secreted by microbes, biodegradable thus environmentally friendly. Some fungi like Schizophyllum commune (a type of mushroom), and Aureobasidium pullulans are reported to produce biopolymers-schizophyllan and pullulan. Hence, we have procured a microbial strain (Schizophyllum commune) from American Type Culture Collection, which is reported for producing a biopolymer and also isolated several Omani strains of Aureobasidium pullulans from different samples. Studies were carried out for maintenance of the strains and primary screening of production media and environmental conditions for growth of S. commune and Omani A. pullulans isolates, for 30 days. The observed optimum growth and production temperature was ≤35 °C for S. commune and Omani A. pullulans isolates. Better growth was observed for both types of fungi under shaking conditions. The initial yield of lyophilized schizophyllan was ≥3.0 g/L, and the yield of pullulan was ≥0.5g/L. Both schizophyllan and pullulan were extracted in crude form and were partially identified by Fourier transform infrared spectroscopy (FTIR), which showed partial similarity in chemical structure with published biopolymers. The produced pullulan and schizophyllan increased the viscosity from 9-20 cp of the control media (without biopolymer) to 20 - 121.4 cp of the cell free broth at 0.1 s-1 shear rate at range of temperatures from 25–45 °C. Enhanced biopolymer production and its physicochemical and rheological properties under different environmental conditions (different temperatures, salt concentrations and wide range of pH), complete characterization and effects on oil recovery enhancement were also investigated in this study.

Keywords: Aureobasidium pullulans, biopolymer, oil recovery enhancement, Schizophyllum commune

Procedia PDF Downloads 389

Authors: Akram Khelaifia, Salah Guettala, Nesreddine Djafar Henni, Rachid Chebili

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Reinforced concrete shear walls are pivotal in protecting buildings from seismic forces by providing strength and stiffness. This study highlights the importance of strategically placing shear walls and optimizing the shear wall-to-floor area ratio in building design. Nonlinear analyses were conducted on an eight-story building situated in a high seismic zone, exploring various scenarios of shear wall positioning and ratios to floor area. Employing the performance-based seismic design (PBSD) approach, the study aims to meet acceptance criteria such as inter-story drift ratio and damage levels. The results indicate that concentrating shear walls in the middle of the structure during the design phase yields superior performance compared to peripheral distributions. Utilizing shear walls that fully infill the frame and adopting compound shapes (e.g., Box, U, and L) enhances reliability in terms of inter-story drift. Conversely, the absence of complete shear walls within the frame leads to decreased stiffness and degradation of shorter beams. Increasing the shear wall-to-floor area ratio in building design enhances structural rigidity and reliability regarding inter-story drift, facilitating the attainment of desired performance levels. The study suggests that a shear wall ratio of 1.0% is necessary to meet validation criteria for inter-story drift and structural damage, as exceeding this percentage leads to excessive performance levels, proving uneconomical as structural elements operate near the elastic range.

Keywords: nonlinear analyses, pushover analysis, shear wall, plastic hinge, performance level

Procedia PDF Downloads 50

Authors: Liane Marcia Freitas Silva, Fernando Augusto Silva Marins, Maria Silene Alexandre Leite

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The adoption of a network structure, like in the supply chains, favors the increase of dependence between companies and, by consequence, their vulnerability. Environment disasters, sociopolitical and economical events, and the dynamics of supply chains elevate the uncertainty of their operation, favoring the occurrence of events that can generate break up in the operations and other undesired consequences. Thus, supply chains are exposed to various risks that can influence the profitability of companies involved, and there are several previous studies that have proposed risk classification models in order to categorize the risks and to manage them. The objective of this paper is to analyze and discuss thirty of these risk classification models by means a theoretical survey. The research method adopted for analyzing and discussion includes three phases: The identification of the types of risks proposed in each one of the thirty models, the grouping of them considering equivalent concepts associated to their definitions, and, the analysis of these risks groups, evaluating their similarities and differences. After these analyses, it was possible to conclude that, in fact, there is more than thirty risks types identified in the literature of Supply Chains, but some of them are identical despite of be used distinct terms to characterize them, because different criteria for risk classification are adopted by researchers. In short, it is observed that some types of risks are identified as risk source for supply chains, such as, demand risk, environmental risk and safety risk. On the other hand, other types of risks are identified by the consequences that they can generate for the supply chains, such as, the reputation risk, the asset depreciation risk and the competitive risk. These results are consequence of the disagreements between researchers on risk classification, mainly about what is risk event and about what is the consequence of risk occurrence. An additional study is in developing in order to clarify how the risks can be generated, and which are the characteristics of the components in a Supply Chain that leads to occurrence of risk.

Keywords: sisks classification, survey, supply chain management, theoretical discussion

Procedia PDF Downloads 633

Authors: Freyedon Ahmadi

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Corporate citizenship is considered as one of the most discussed topics in the developed countries, in which a citizen considers a Corporate just like a usual citizen with every civil right as respectful for corporate as for actual citizens, and in return citizens expect that corporate would pay a reciprocal respect to them. The current study’s purpose is to identify the impact of the current state of corporate citizenship along effective factors on its condition on industrial producing units, in order to find an accession plane for corporate citizenship development. In this study corporate citizenship is studied in four dimensions like legal corporate, economical corporate, ethical corporate and voluntary corporate. Moreover, effective factors’ impact on corporate citizenship is explored based on threefold dimensional model: behavioral, structural, and content factors, as well. In this study, 50 corporate of Food industry and of petrochemical industry, along with 200 selected individuals from directors’ board on Tehran province’s scale with stratified random sampling method, are chosen as actuarial sample. If based on functional goal and compilation methods, the present study is a description of correlation type; questionnaire is used for accumulation of initial Data. For Instrument Validity expert’s opinion is used and structural equations and its reliability is qualified by using Cronbach Alpha. The results of this study indicate that close to 70 percent of under survey corporate have not a good condition in corporate citizenship. And all of structural factors, behavioral factors, contextual factors, have a great deal of impression and impact on the advent corporate citizenship behavior in the producing Units. Among the behavioral factors, social responsibility; among structural factors, organic structure and human centered orientation, medium size, high organizational capacity; and among the contextual factors, the clientele’s positive viewpoints toward corporate had the utmost importance in impression on under survey Producing units.

Keywords: corporate citizenship, structural factors, behavioral factors, contextual factors, producing units

Procedia PDF Downloads 230

Authors: Nigina Toktasynova, Sholpan Sagyndykova, Zhanat Kenzhebayeva, Maksat Kalimoldayev, Mariya Ishimova, Irbulat Utepbergenov

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Any business needs a stable operation and continuous improvement, therefore it is necessary to constantly interact with the environment, to analyze the work of the enterprise in terms of employees, executives and consumers, as well as to correct any inconsistencies of certain types of processes and their aggregate. In the case of heat supply organizations, in addition to suppliers, local legislation must be considered which often is the main regulator of pricing of services. In this case, the process approach used to build a functional organizational structure in these types of businesses in Kazakhstan is a challenge not only in the implementation, but also in ways of analyzing the employee's salary. To solve these problems, we investigated the management system of heating enterprise, including strategic planning based on the balanced scorecard (BSC), quality management in accordance with the standards of the Quality Management System (QMS) ISO 9001 and analysis of the system based on expert judgment using fuzzy inference. To carry out our work we used the theory of fuzzy sets, the QMS in accordance with ISO 9001, BSC according to the method of Kaplan and Norton, method of construction of business processes according to the notation IDEF0, theory of modeling using Matlab software simulation tools and graphical programming LabVIEW. The results of the work are as follows: We determined possibilities of improving the management of heat-supply plant-based on QMS; after the justification and adaptation of software tool it has been used to automate a series of functions for the management and reduction of resources and for the maintenance of the system up to date; an application for the analysis of the QMS based on fuzzy inference has been created with novel organization of communication software with the application enabling the analysis of relevant data of enterprise management system.

Keywords: balanced scorecard, heat supply, quality management system, the theory of fuzzy sets

Procedia PDF Downloads 367

Authors: Arzu K. Kamberli, Tolga Ulusoy

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Technological developments and the resulting global communication have made the 21st century when large capitals are moved from one end to the other via a button. As a result, the flow of capital inflows has accelerated, and capital inflow has brought with it crisis-related infectiousness. Considering the irrational human behavior, the financial crisis in the world under the influence of the whole world has turned into the basic problem of the countries and increased the interest of the researchers in the reasons of the crisis and the period in which they lived. Therefore, the complex nature of the financial crises and its linearly unexplained structure have also been included in the new discipline, econophysics. As it is known, although financial crises have prediction mechanisms, there is no definite information. In this context, in this study, using the concept of electric field from the electrostatic part of physics, an early econophysical approach for global financial crises was studied. The aim is to define a model that can take place before the financial crises, identify financial fragility at an earlier stage and help public and private sector members, policy makers and economists with an econophysical approach. 2001 Turkey crisis has been assessed with data from Turkish Central Bank which is covered between 1992 to 2007, and for 2001 Argentina crisis, data was taken from IMF and the Central Bank of Argentina from 1997 to 2007. As an econophysical method, an analogy is used between the Gauss's law used in the calculation of the electric field and the forecasting of the financial crisis. The concept of Φ (Financial Flux) has been adopted for the pre-warning of the crisis by taking advantage of this analogy, which is based on currency movements and money mobility. For the first time used in this study Φ (Financial Flux) calculations obtained by the formula were analyzed by Matlab software, and in this context, in 2001 Turkey and Argentina Crisis for Φ (Financial Flux) crisis of values has been confirmed to give pre-warning.

Keywords: econophysics, financial crisis, Gauss's Law, physics

Procedia PDF Downloads 153

Authors: Lily Ranjbar, Haori Yang

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Online education has been around for several decades, but the importance of online education became evident after the COVID-19 pandemic. Eventhough the online delivery approach works well for knowledge building through delivering content and oversight processes, it has limitations in developing hands-on laboratory skills, especially in the STEM field. During the pandemic, many education institutions faced numerous challenges in delivering lab-based courses, especially in the STEM field. Also, many students worldwide were unable to practice working with lab equipment due to social distancing or the significant cost of highly specialized equipment. The laboratory plays a crucial role in nuclear science and engineering education. It can engage students and improve their learning outcomes. In addition, online education and virtual labs have gained substantial popularity in engineering and science education. Therefore, developing virtual labs is vital for institutions to deliver high-class education to their students, including their online students. The School of Nuclear Science and Engineering (NSE) at Oregon State University, in partnership with SpectralLabs company, has developed an Advanced Virtual Radiation Detection and Measurement Lab (AVR-DML) to offer a fully online Master of Health Physics program. It was essential for us to use a system that could simulate nuclear modules that accurately replicate the underlying physics, the nature of radiation and radiation transport, and the mechanics of the instrumentations used in the real radiation detection lab. It was all accomplished using a Realistic, Adaptive, Interactive Learning System (RAILS). RAILS is a comprehensive software simulation-based learning system for use in training. It is comprised of a web-based learning management system that is located on a central server, as well as a 3D-simulation package that is downloaded locally to user machines. Users will find that the graphics, animations, and sounds in RAILS create a realistic, immersive environment to practice detecting different radiation sources. These features allow students to coexist, interact and engage with a real STEM lab in all its dimensions. It enables them to feel like they are in a real lab environment and to see the same system they would in a lab. Unique interactive interfaces were designed and developed by integrating all the tools and equipment needed to run each lab. These interfaces provide students full functionality for data collection, changing the experimental setup, and live data collection with real-time updates for each experiment. Students can manually do all experimental setups and parameter changes in this lab. Experimental results can then be tracked and analyzed in an oscilloscope, a multi-channel analyzer, or a single-channel analyzer (SCA). The advanced virtual radiation detection and measurement laboratory developed in this study enabled the NSE school to offer a fully online MHP program. This flexibility of course modality helped us to attract more non-traditional students, including international students. It is a valuable educational tool as students can walk around the virtual lab, make mistakes, and learn from them. They have an unlimited amount of time to repeat and engage in experiments. This lab will also help us speed up training in nuclear science and engineering.

Keywords: advanced radiation detection and measurement, virtual laboratory, realistic adaptive interactive learning system (rails), online education in stem fields, student engagement, stem online education, stem laboratory, online engineering education

Procedia PDF Downloads 89

Authors: R. C. Tiwari, N. P. Bhandary, D. B. Thapa Chhetri, R. Yatabe

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The research enlightens the various issues of lake expansion and stability of the moraine dam of Imja lake. The Imja lake considered that the world highest altitude lake (5010m from m.s.l.), located in the Khumbu, Sagarmatha region of Nepal (27.90 N and 86.90 E) was reported as one of the fast growing glacier lakes in the Nepal Himalaya. The research explores a common phenomenon of lake expansion and stability issues of moraine dam to justify the necessity of lake lowering efforts if any in future in other glacier lakes in Nepal Himalaya. For this, we have explored the root causes of rapid lake expansion along with crucial factors responsible for the stability of moraine mass. This research helps to understand the structure of moraine dam and the ice, water and moraine interactions to the strength of moraine dam. The nature of permafrost layer and its effects on moraine dam stability is also studied here. The detail Geo-Technical properties of moraine mass of Imja lake gives a clear picture of the strength of the moraine material and their interactions. The stability analysis of the moraine dam under the consideration of strong ground motion of 7.8Mw 2015 Barpak-Gorkha and its major aftershock 7.3Mw Kodari, Sindhupalchowk-Dolakha border, Nepal earthquakes have also been carried out here to understand the necessity of lake lowering efforts. The lake lowering effort was recently done by Nepal Army by constructing an open channel and lowered 3m. And, it is believed that the entire region is now safe due to continuous draining of lake water by 3m. But, this option does not seem adequate to offer a significant risk reduction to downstream communities in this much amount of volume and depth, lowering as in the 75 million cubic meter water impounded with an average depth of 148.9m.

Keywords: finite element method, glacier, moraine, stability

Procedia PDF Downloads 213

Authors: Zhiwu Zheng, Prakhar Kumar, Sigurd Wagner, Naveen Verma, James C. Sturm

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Soft robots have drawn great interest recently due to a rich range of possible shapes and motions they can take on to address new applications, compared to traditional rigid robots. Large-area electronics (LAE) provides a unique platform for creating soft robots by leveraging thin-film technology to enable the integration of a large number of actuators, sensors, and control circuits on flexible sheets. However, the rich shapes and motions possible, especially when interacting with complex environments, pose significant challenges to forming well-generalized and robust models necessary for robot design and control. In this work, we describe an analytical model for predicting the shape and locomotion of a flexible (steel-foil-based) piezoelectric-actuated 2D robot based on Euler-Bernoulli beam theory. It is nominally (unpowered) lying flat on the ground, and when powered, its shape is controlled by an array of piezoelectric thin-film actuators. Key features of the models are its ability to incorporate the significant effects of gravity on the shape and to precisely predict the spatial distribution of friction against the contacting surfaces, necessary for determining inchworm-type motion. We verified the model by developing a distributed discrete element representation of a continuous piezoelectric actuator and by comparing its analytical predictions to discrete-element robot simulations using PyBullet. Without gravity, predicting the shape of a sheet with a linear array of piezoelectric actuators at arbitrary voltages is straightforward. However, gravity significantly distorts the shape of the sheet, causing some segments to flatten against the ground. Our work includes the following contributions: (i) A self-consistent approach was developed to exactly determine which parts of the soft robot are lifted off the ground, and the exact shape of these sections, for an arbitrary array of piezoelectric voltages and configurations. (ii) Inchworm-type motion relies on controlling the relative friction with the ground surface in different sections of the robot. By adding torque-balance to our model and analyzing shear forces, the model can then determine the exact spatial distribution of the vertical force that the ground is exerting on the soft robot. Through this, the spatial distribution of friction forces between ground and robot can be determined. (iii) By combining this spatial friction distribution with the shape of the soft robot, in the function of time as piezoelectric actuator voltages are changed, the inchworm-type locomotion of the robot can be determined. As a practical example, we calculated the performance of a 5-actuator system on a 50-µm thick steel foil. Piezoelectric properties of commercially available thin-film piezoelectric actuators were assumed. The model predicted inchworm motion of up to 200 µm per step. For independent verification, we also modelled the system using PyBullet, a discrete-element robot simulator. To model a continuous thin-film piezoelectric actuator, we broke each actuator into multiple segments, each of which consisted of two rigid arms with appropriate mass connected with a 'motor' whose torque was set by the applied actuator voltage. Excellent agreement between our analytical model and the discrete-element simulator was shown for both for the full deformation shape and motion of the robot.

Keywords: analytical modeling, piezoelectric actuators, soft robot locomotion, thin-film technology

Procedia PDF Downloads 180