Search results for: open space

Authors: Angelo Lerro, Manuela Battipede, Piero Gili, Alberto Brandl

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Redundancy requirements for UAV (Unmanned Aerial Vehicle) are hardly faced due to the generally restricted amount of available space and allowable weight for the aircraft systems, limiting their exploitation. Essential equipment as the Air Data, Attitude and Heading Reference Systems (ADAHRS) require several external probes to measure significant data as the Angle of Attack or the Sideslip Angle. Previous research focused on the analysis of a patented technology named Smart-ADAHRS (Smart Air Data, Attitude and Heading Reference System) as an alternative method to obtain reliable and accurate estimates of the aerodynamic angles. This solution is based on an innovative sensor fusion algorithm implementing soft computing techniques and it allows to obtain a simplified inertial and air data system reducing external devices. In fact, only one external source of dynamic and static pressures is needed. This paper focuses on the benefits which would be gained by the implementation of this system in UAV applications. A simplification of the entire ADAHRS architecture will bring to reduce the overall cost together with improved safety performance. Smart-ADAHRS has currently reached Technology Readiness Level (TRL) 6. Real flight tests took place on ultralight aircraft equipped with a suitable Flight Test Instrumentation (FTI). The output of the algorithm using the flight test measurements demonstrates the capability for this fusion algorithm to embed in a single device multiple physical and virtual sensors. Any source of dynamic and static pressure can be integrated with this system gaining a significant improvement in terms of versatility.

Keywords: aerodynamic angles, air data system, flight test, neural network, unmanned aerial vehicle, virtual sensor

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Authors: Samih Ahmed, Guayente Minchot, Fritz King, Mikael Hallgren

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The stress ribbon system has numerous advantages that include but are not limited to increasing overall stiffness, control deflections, and reduction of materials consumption, which in turn, reduces the load and the cost. Nevertheless, its use is usually limited to bridges, in particular, pedestrian bridges; this can be attributed to the insufficient space that buildings' usually have for end supports, and/or back- stayed cables, that can accommodate the expected high pull-out forces occurring at the cables' ends. In this work, the roof of Västerås Travel Center, which will become one of the longest cable suspended roofs in the world, was chosen as a case study. The aim was to investigate the optimal technique to model the post-tensioned stress ribbon system for the roof structure using the FEM software SAP2000 and to assess any possible reduction in the pull-out forces, deflections, and concrete stresses. Subsequently, a conventional cable suspended roof was simulated using SAP2000, and compared to the post-tension stress ribbon system in order to examine the potential of the latter. Moreover, the effects of temperature loads and support movements on the final design loads were examined. Based on the study, a few practical recommendations concerning the construction method and the iterative design process, required to meet the architectural geometrical demands, are stated by the authors. The results showed that the post-tensioned stress ribbon system reduces the concrete stresses, overall deflections, and more importantly, reduces the pull-out forces and the vertical reactions at both ends by up to 16% and 11%, respectively, which substantially reduces the design forces for the support structures. The magnitude of these reductions was found to be highly correlated to the applied prestressing force, making the size of the prestressing force a key factor in the design.

Keywords: cable suspended, post-tension, roof structure, SAP2000, stress ribbon

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Authors: Aashutosh A. Tadse, Kush Mehta, Hardik Vyas

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Friction Stir Welding is a process in which an FSW tool produces friction heat and thus penetrates through the junction and upon rotation carries out the weld by exchange of material within the 2 metals being welded. It involves holding the workpieces stiff enough to bear the force of the tool moving across the junction to carry out a successful weld. The weld that has flat plates as workpieces, has a quite simpler geometry in terms of fixture holding them. In the case of FSW of pipes, the pipes need to be held firm with the chucks and jaws according to the diameter of the pipes being welded; the FSW tool is then revolved around the pipes to carry out the weld. Machine requires a larger area and it becomes more costly because of such a setup. To carry out the weld on the Milling machine, the newly designed fixture must be set-up on the table of milling machine and must facilitate rotation of pipes by the motor being shafted to one end of the fixture, and the other end automatically rotated because of the rotating jaws held tight enough with the pipes. The set-up has tapered cones as the jaws that would go in the pipes thus holding it with the help of its knurled surface providing the required grip. The process has rotation of pipes with the stationary rotating tool penetrating into the junction. The FSW on pipes in this process requires a very low RPM of pipes to carry out a fine weld and the speed shall change with every combination of material and diameter of pipes, so a variable speed setting motor shall serve the purpose. To withstand the force of the tool, an attachment to the shaft is provided which will be diameter specific that will resist flow of material towards the center during the weld. The welded joint thus carried out will be proper to required standards and specifications. Current industrial requirements state the need of space efficient, cost-friendly and more generalized form of fixtures and set-ups of machines to be put up. The proposed design considers every mentioned factor and thus proves to be positive in the same.

Keywords: force of tool, friction stir welding, milling machine, rotation of pipes, tapered cones

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Authors: Aishwarya Pothula

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Euthanasia in India is a politically dormant policy issue in the sense that discussions around it are sporadic in nature (usually with developments in specific cases) and it stays as a dominant issue in the public domain for a fleeting period. In other words, it is a non-political issue that has been unable to successfully get on the policy agenda. This paper studies how the Supreme Court of India (SC) plays a role in euthanasia’s policy making. In 2011, the SC independently put a law in place that legalized passive euthanasia through its judgement in the Aruna Shanbaug v. Union of India case. According to this, it is no longer illegal to withhold/withdraw a patient’s medical treatment in certain cases. This judgement, therefore, is the empirical focus of this paper. The paper essentially employs two techniques of discourse analysis to study the SC’s system of argumentation. The two methods, Text Analysis using Gasper’s Analysis Table and Frame Analysis – are complemented by two discourse techniques called metaphor analysis and lexical analysis. The framework within which the analysis is conducted lies in 1) the judicial process of India, i.e. the SC procedures and the Constitutional rules and provisions, and 2) John W. Kingdon’s theory of policy windows and policy entrepreneurs. The results of this paper are three-fold: first, the SC dismiss the petitioner’s request for passive euthanasia on inadequate and weak grounds, thereby setting no precedent for the historic law they put in place. In other words, they leave the decision open for the Parliament to act upon. Hence the judgement, as opposed to arguments by many, is by no means an instance of judicial activism/overreach. Second, they define euthanasia in a way that resonates with existing broader societal themes. They combine this with a remarkable use of authoritative and protective tones/stances to settle at an intermediate position that balances the possible opposition to their role in the process and what they (perhaps) perceive to be an optimal solution. Third, they soften up the policy community (including the public) to the idea of passive euthanasia leading it towards a Parliamentarian legislation. They achieve this by shaping prevalent principles, provisions and worldviews through an astute use of the legal instruments at their disposal. This paper refers to this unconventional role of the SC as ‘judicial entrepreneurship’ which is also the first scholarly contribution towards research on euthanasia as a policy issue in India.

Keywords: argumentation analysis, Aruna Ramachandra Shanbaug, discourse analysis, euthanasia, judicial entrepreneurship, policy-making process, supreme court of India

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Authors: Veliswa Nonfundo Hoho, Jabulani Gilford Kheswa

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This paper reports on teenage motherhood and its adverse outcomes on the academic performance, emotional well-being and sexual relationships that adolescent females encounter. Drawing from Ryff’s six dimensions of psychological well-being and Bronfenbrenner’s ecological model which underpinned this study, teenage motherhood has been found to link with multiple factors such as poverty, negative self-esteem, substance abuse, cohabitation, intimate partner violence and ill-health. Furthermore, research indicates that in schools where educators fail to perform their duties as loco-parentis to motivate adolescent females learners who are mothers, absenteeism, poor academic performance and learned helplessness, are likely. The aim of this research was two-fold, namely; (i) to determine the impact of teenage motherhood on the psychological well-being of the teenage mothers and (ii) to investigate the policies which protect the human rights of teenage mothers attending secondary schools. In a qualitative study conducted in one secondary school, Fort Beaufort, Eastern Cape, South Africa, fifteen Xhosa-speaking teenage mothers, aged 15-18 years old, were interviewed. The sample was recruited by means of snow-ball sampling. To safeguard the human dignity of the respondents, informed consent, confidentiality, anonymity and privacy of the respondents were assured. For trustworthiness, this research ensured that credibility, neutrality, and transferability, are met. Following an axial and open coding of responses, five themes were identified; Health issues of teenage mothers, lack of support, violation of human rights, impaired sense of purpose in life and intimate partner-violence. From these findings, it is clear that teenage mothers lack resilience and are susceptible to contract sexually transmitted infections and HIV/AIDS because they are submissive and hopeless. Furthermore, owing to stigma that the teenage mothers' experience from family members, they resort to alcohol and drug abuse, and feel demotivated to bond with their babies. In conclusion, the recommendations are that the Health and Social Development departments collaborate to empower the psychological well-being of teenage mothers. Furthermore, school policies on discrimination should be enacted and consistently implemented.

Keywords: depression, discrimination, self-esteem, teenage mothers

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Authors: Natalia Uribe Corrales, Santiago Henao Villegas

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Introduction: The management of pigs in the holding pens at the slaughterhouses is a key point to minimize levels of stress and fear, improve efficiency, maintain a good quality of meat and avoid economic losses. Holding pens should guarantee drinking water continuously, a minimum space of 1.2 m2/ animal; As well as an adequate management in the conduction of the animals towards stun. Objective: To characterize the management practices in holding pens in slaughterhouses in the Valle de Aburrá. Methods: A descriptive cross - sectional study was carried out in Valle de Aburrá benefit plants, which were authorized by National Institute for Food and Medicine Surveillance (INVIMA). Variables such as management mechanisms to the pens, time of housing, water supply, load density, vocalization, slips and falls of the animals in the pens and mechanism of conduction towards desensitization were analyzed. Results: 225 pigs were analyzed, finding that 35.6% were lowered with slaps from the trucks to the waiting pens; The lairage time was greater than 10 hours in 16% of the animals; 12.9% of pigs had no water permanently; 40.9% was subjected to a high load density, while 19.6% had a low load density. Regarding aspects of animal welfare, 37.3% presented high vocalizations; 29.3% and 14.2% presented slips or falls respectively. Regarding the mechanism of conduction towards desensitization, slapping was used in 56% and electrical prod in 4%. Conclusions: It is necessary to continue promoting the learning of the densities of load, since both high and low densities generate inconveniences in animal welfare, favoring the appearance of lesions and stress in the animals. Also, to promote the rule of permanent water in the pens and a time of housing less than 10 hours. In relation to the driving mechanisms, it is necessary to continue animal husbandry campaigns, encouraging the use of other alternatives such as boards or panels to assist the movement of pigs.

Keywords: animal welfare, quality of meat, swine, waiting pens

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Authors: Alana E. Jansen

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With such a large proportion of organisations relying on the use of team-based structures, it is surprising that so few teams would be classified as high-performance teams. While the impact of team composition on performance has been researched frequently, there have been conflicting findings as to the effects, particularly when examined alongside other team factors. To broaden the theoretical perspectives on this topic and potentially explain some of the inconsistencies in research findings left open by other various models of team effectiveness and high-performing teams, the present study aims to use the Job-Demands-Resources model, typically applied to burnout and engagement, as a framework to examine how team composition factors (particularly diversity in team member characteristics) can facilitate or hamper team effectiveness. This study used a virtual interview design where participants were asked to both rate and describe their experiences, in one high-performing and one low-performing team, over several factors relating to demands, resources, team composition, and team effectiveness. A semi-structured interview protocol was developed, which combined the use of the Likert style and exploratory questions. A semi-targeted sampling approach was used to invite participants ranging in age, gender, and ethnic appearance (common surface-level diversity characteristics) and those from different specialties, roles, educational and industry backgrounds (deep-level diversity characteristics). While the final stages of data analyses are still underway, thematic analysis using a grounded theory approach was conducted concurrently with data collection to identify the point of thematic saturation, resulting in 35 interviews being completed. Analyses examine differences in perceptions of demands and resources as they relate to perceived team diversity. Preliminary results suggest that high-performing and low-performing teams differ in perceptions of the type and range of both demands and resources. The current research is likely to offer contributions to both theory and practice. The preliminary findings suggest there is a range of demands and resources which vary between high and low-performing teams, factors which may play an important role in team effectiveness research going forward. Findings may assist in explaining some of the more complex interactions between factors experienced in the team environment, making further progress towards understanding the intricacies of why only some teams achieve high-performance status.

Keywords: diversity, high-performing teams, job demands and resources, team effectiveness

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Authors: Shih-Ting Yang, Chih-Yun Lin, Ming-Yu Li, Jhong-Ting Syue, Wei-Ming Huang

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Global positioning system (GPS) has become increasing precise in recent years, and the location-based service (LBS) has developed rapidly. Take the example of finding a parking lot (such as Parking apps). The location-based service can offer immediate information about a nearby parking lot, including the information about remaining parking spaces. However, it cannot provide expected search results according to the requirement situations of users. For that reason, this paper develops a “Location-based Search Approach according to Users’ Application Scenario” according to the location-based search and demand determination to help users obtain the information consistent with their requirements. The “Location-based Search Approach based on Users’ Application Scenario” of this paper consists of one mechanism and three kernel modules. First, in the Information Pre-processing Mechanism (IPM), this paper uses the cosine theorem to categorize the locations of users. Then, in the Information Category Evaluation Module (ICEM), the kNN (k-Nearest Neighbor) is employed to classify the browsing records of users. After that, in the Information Volume Level Determination Module (IVLDM), this paper makes a comparison between the number of users’ clicking the information at different locations and the average number of users’ clicking the information at a specific location, so as to evaluate the urgency of demand; then, the two-dimensional space is used to estimate the application situations of users. For the last step, in the Location-based Search Module (LBSM), this paper compares all search results and the average number of characters of the search results, categorizes the search results with the Manhattan Distance, and selects the results according to the application scenario of users. Additionally, this paper develops a Web-based system according to the methodology to demonstrate practical application of this paper. The application scenario-based estimate and the location-based search are used to evaluate the type and abundance of the information expected by the public at specific location, so that information demanders can obtain the information consistent with their application situations at specific location.

Keywords: data mining, knowledge management, location-based service, user application scenario

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Authors: Daniele Calvi, Loris Franchi, Sabrina Corpino

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Thanks to the latest Mars mission, the planetary exploration has made enormous strides over the past ten years increasing the interest of the scientific community and beyond. These missions aim to fulfill many complex operations which are of paramount importance to mission success. Among these, a special mention goes to the Entry, Descent and Landing (EDL) functions which require a dedicated system to overcome all the obstacles of these critical phases. The general objective of the system is to safely bring the spacecraft from orbital conditions to rest on the planet surface, following the designed mission profile. For this reason, this work aims to develop a simulation tool integrating the re-entry trajectory algorithm in order to support the EDL design during the preliminary phase of the mission. This tool was used on a reference unmanned mission, whose objective is finding bio-evidence and bio-hazards on Martian (sub)surface in order to support the future manned mission. Regarding the concept of operations (CONOPS) of the mission, it concerns the use of Space Penetrator Systems (SPS) that will descend on Mars surface following a ballistic fall and will penetrate the ground after the impact with the surface (around 50 and 300 cm of depth). Each SPS shall contain all the instrumentation required to sample and make the required analyses. Respecting the low-cost and low-mass requirements, as result of the tool, an Entry Descent and Impact (EDI) system based on inflatable structure has been designed. Hence, a solution could be the one chosen by Finnish Meteorological Institute in the Mars Met-Net mission, using an inflatable Thermal Protection System (TPS) called Inflatable Braking Unit (IBU) and an additional inflatable decelerator. Consequently, there are three configurations during the EDI: at altitude of 125 km the IBU is inflated at speed 5.5 km/s; at altitude of 16 km the IBU is jettisoned and an Additional Inflatable Braking Unit (AIBU) is inflated; Lastly at about 13 km, the SPS is ejected from AIBU and it impacts on the Martian surface. Since all parameters are evaluated, it is possible to confirm that the chosen EDI system and strategy verify the requirements of the mission.

Keywords: EDL, Mars, mission, SPS, TPS

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Authors: Legkikh Victoria

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The purpose of keeping bi/multilingualism is usually a way to let the child speak two/three languages at the same level. The main problem which normally appears is a mixed language or a domination of one language. The same level of two or more languages would be ideal but practically not easily reachable. So it was made an experiment with a girl with a natural multilingualism as an attempt to avoid a dominant language in the preschool age. The girl lives in Germany and the main languages for her are Italian, Russian and German but she also hears every day English. ‘One parent – one language’ strategy was used since the beginning so Italian and Russian were spoken to her since her birth, English was spoken between the parents and when she was 1,5 it was added German as a language of a nursery. In order to avoid a dominant language, she was always put in international groups with activity in different languages. Even if it was not possible to avoid an interference of languages in this case we can talk not only about natural multilingualism but also about balanced bilingualism in preschool time. The languages have been developing in parallel with different accents in a different period. Now at the age of 6 we can see natural horizontal multilingualism Russian/Italian/German/English. At the moment, her Russian/Italian bilingualism is balanced. German vocabulary is less but the language is active and English is receptive. We can also see a reciprocal interference of all the three languages (English is receptive so the simple phrases are normally said correctly but they are not enough to judge the level of language interference and it is not noticed any ‘English’ mistakes in other languages). After analysis of the state of every language, we can see as a positive and negative result of the experiment. As a positive result we can see that in the age of 6 the girl does not refuse any language, three languages are active, she differentiate languages and even if she says a word from another language she notifies that it is not a correct word, and the most important are the fact, that she does not have a preferred language. As a prove of the last statement it is to be noticed not only her self-identification as ‘half Russian and half Italian’ but also an answer to the question about her ‘mother tongue’: ‘I do not know, probably, when I have my own children I will speak one day Russian and one day Italian and sometimes German’. As a negative result, we can notice that not only a development of all the three languages are a little bit slower than it is supposed for her age but since she does not have a dominating language she also does not have a ‘perfect’ language and the interference is reciprocal. In any case, the experiment shows that it is possible to keep at least two languages without a preference in a pre-school multilingual space.

Keywords: balanced bilingualism, language interference, natural multilingualism, preschool multilingual education

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Authors: Beate Weyland

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The interdisciplinary laboratory EDEN, Educational Environments with Nature, born in 2020 at the Faculty of Education of the Free University of Bolzano, is working on a research path initiated in 2012 on the relationship between pedagogy and architecture in the design process of school buildings. Between 2016 and 2018, advisory support activity for schools was born, which combined the need to qualify the physical spaces of the school with the need to update teaching practices and develop school organization with the aim of improving pupils' and teachers' sense of well-being. The goal of accompanying the development of school communities through research-training paths concerns the process of designing together pedagogical-didactic and architectural environments in which to stage the educational relationship, involving professionals from education, educational research, architecture and design, and local administration. Between 2019 and 2024, more than 30 schools and educational communities throughout Italy have entered into research-training agreements with the university, focusing increasingly on the need to create new spaces and teaching methods capable of imagining educational spaces as places of well-being and where cultural development can be presided over. The paper will focus on the presentation of the research path and on the mixed methods used to support schools and educational communities: identification of the research question, development of the research objective, experimentation, and data collection for analysis and reflection. School and educational communities are involved in a participative and active manner. The quality of the action-research work is enriched by a special focus on the relationship with plants and nature in general. Plants are seen as mediators of processes that unhinge traditional didactics and invite teachers, students, parents, and administrators to think about the quality of learning spaces and relationships based on well-being. The contribution is characterized by a particular focus on research methodologies and tools developed together with teachers to answer the issues raised and to measure the impact of the actions undertaken.

Keywords: school development, learning space, wellbeing, plants and nature

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Authors: Bekir Turedi

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Exploiting the potential of perovskite single-crystal solar cells in optoelectronic applications necessitates overcoming a significant challenge: the low charge collection efficiency at increased thickness, which has restricted their deployment in radiation detectors and nuclear batteries. Our research details a promising approach to this problem, wherein we have successfully fabricated single-crystal MAPbI3 solar cells employing a space-limited inverse temperature crystallization (ITC) methodology. Remarkably, these cells, up to 400-fold thicker than current-generation perovskite polycrystalline films, maintain a high charge collection efficiency even without external bias. The crux of this achievement lies in the long electron diffusion length within these cells, estimated to be around 0.45 mm. This extended diffusion length ensures the conservation of high charge collection and power conversion efficiencies, even as the thickness of the cells increases. Fabricated cells at 110, 214, and 290 µm thickness manifested power conversion efficiencies (PCEs) of 20.0, 18.4, and 14.7% respectively. The single crystals demonstrated nearly optimal charge collection, even when their thickness exceeded 200 µm. Devices of thickness 108, 214, and 290 µm maintained 98.6, 94.3, and 80.4% of charge collection efficiency relative to their maximum theoretical short-circuit current value, respectively. Additionally, we have proposed an innovative, self-consistent technique for ascertaining the electron-diffusion length in perovskite single crystals under operational conditions. The computed electron-diffusion length approximated 446 µm, significantly surpassing previously reported values for this material. In conclusion, our findings underscore the feasibility of fabricating halide perovskite single-crystal solar cells of hundreds of micrometers in thickness while preserving high charge extraction efficiency and PCE. This advancement paves the way for developing perovskite-based optoelectronics necessitating thicker active layers, such as X-ray detectors and nuclear batteries.

Keywords: perovskite, solar cell, single crystal, diffusion length

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Authors: Wilfred Emmannuel Dzasu, Sani Usman Kunya, Inuwa Yusuf Mohammed, Moses Jonathan Gambo

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The research aimed at investigating and identifying the strategies for enhancing access to microfinance for housing provision in the informal sector of North East Nigeria, with a focus on addressing the critical issue of housing poverty and lack of access to affordable housing finance among low-income households in the informal sector. The study employed an exploratory sequential mixed method design, combining both qualitative and quantitative data collection and analysis techniques. In the qualitative phase, 12 participants from microfinance institutions (MFIs) in four selected states (Adamawa, Bauchi, Gombe, and Taraba) were interviewed. The interviews were conducted using an interview guide with open-ended questions and were recorded with the consent of the respondents. In the quantitative phase, a survey strategy was adopted to collect data from 500 questionnaires distributed to informal sector workers (ISWs) in the study area. A total of 350 questionnaires were returned, representing a 70.0% response rate. The most preferred strategy for improving access to housing microfinance among ISWs is aggressive awareness of housing financing options by MFIs, with a mean score of 4.213; the most important strategy for improving access to housing microfinance among MFIs is close monitoring and adequate supervision of housing loan beneficiaries by MFIs, with a mean score of 4.675. The study identified several government-related strategies that are necessary for enhancing access to housing microfinance, including the provision of grants and subsidized intervention funds for housing, improvement in infrastructures to aid housing developments, and adequate measures for checking inflation/price fluctuation of building materials. The study also identified several MFI-related strategies that are necessary for enhancing access to housing microfinance, including deliberate expansion in the capital bases of MFIs, adequate training and capacity development of MFIs staff on relevant skills in housing micro-financing, and introduction of loan products that suit the incremental building needs of informal sector workers. Overall, the study highlights the need for a combination of government-related and MFI-related strategies to enhance access to microfinance for housing provision in the informal sector of North East Nigeria.

Keywords: finanace, microfinance, housing, North East Nigeria

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Authors: Clare Cunningham

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Whilst there is a strong global research base on the benefits of structured writing retreats and similar provisions, such as Shut Up and Write events, for academic staff and postgraduate researchers, very little has been published about the worth of such events for undergraduate students. This is despite the fact that, internationally, undergraduate student researchers experience similar pressures, distractions and feelings towards writing as those who are at more senior levels within the academy. This paper reports on a mixed-methods study with cohorts of third-year undergraduate students over the course of four academic years. This involved a range of research instruments adopted over the four years of the study. They include the administration of four questionnaires across three academic years, a collection of ethnographic recordings in the second year, and the collation of reflective journal entries and evaluations from all four years. The final two years of data collection took place during the period of Covid-19 restrictions when writing retreats moved to the virtual space which adds an additional dimension of interest to the analysis. The analysis involved the collation of quantitative questionnaire data to observe patterns in expressions of attitudes towards writing. Qualitative data were analysed thematically and used to corroborate and support the quantitative data when appropriate. The resulting data confirmed that one of the biggest challenges for undergraduate students mirrors those reported in the findings of studies focused on more experienced researchers. This is not surprising, especially given the number of undergraduate students who now work alongside their studies, as well as the increasing number who have caring responsibilities, but it has, as yet, been under-reported. The data showed that the groups of writing retreat participants all had very positive experiences, with accountability, a sense of community and procrastination avoidance some of the key aspects. The analysis revealed the sometimes transformative power of these events for a number of these students in terms of changing the way they viewed writing and themselves as writers. The data presented in this talk will support the proposal that retreats should much more widely be offered to undergraduate students across the world.

Keywords: academic writing, students, undergraduates, writing retreat

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Authors: Lydia Novozhilova, Vladimir Urazhdin

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An optimization problem for reinforced thin-walled vessels under uniform external pressure is considered. The conventional approaches to optimization generally start with pre-defined geometric parameters of the vessels, and then employ analytic or numeric calculations and/or experimental testing to verify functionality, such as stability under the projected conditions. The proposed approach consists of two steps. First, the feasibility domain will be identified in the multidimensional parameter space. Every point in the feasibility domain defines a design satisfying both geometric and functional constraints. Second, an objective function defined in this domain is formulated and optimized. The broader applicability of the suggested methodology is maximized by implementing the Support Vector Machines (SVM) classification algorithm of machine learning for identification of the feasible design region. Training data for SVM classifier is obtained using the Simulation package of SOLIDWORKS®. Based on the data, the SVM algorithm produces a curvilinear boundary separating admissible and not admissible sets of design parameters with maximal margins. Then optimization of the vessel parameters in the feasibility domain is performed using the standard algorithms for the constrained optimization. As an example, optimization of a ring-stiffened closed cylindrical thin-walled vessel with semi-spherical caps under high external pressure is implemented. As a functional constraint, von Mises stress criterion is used but any other stability constraint admitting mathematical formulation can be incorporated into the proposed approach. Suggested methodology has a good potential for reducing design time for finding optimal parameters of thin-walled vessels under uniform external pressure.

Keywords: design parameters, feasibility domain, von Mises stress criterion, Support Vector Machine (SVM) classifier

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Authors: Aravind Ravichandran, Marc Ramuz, Sylvain Blayac

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With the rapid development of wearable electronics and sensor networks, batteries cannot meet the sustainable energy requirement due to their limited lifetime, size and degradation. Ambient energies such as wind have been considered as an attractive energy source due to its copious, ubiquity, and feasibility in nature. With miniaturization leading to high-power and robustness, triboelectric nanogenerator (TENG) have been conceived as a promising technology by harvesting mechanical energy for powering small electronics. TENG integration in large-scale applications is still unexplored considering its attractive properties. In this work, a state of the art design TENG based on wind venturi system is demonstrated for use in any complex environment. When wind introduces into the air gap of the homemade TENG venturi system, a thin flexible polymer repeatedly contacts with and separates from electrodes. This device structure makes the TENG suitable for large scale harvesting without massive volume. Multiple stacking not only amplifies the output power but also enables multi-directional wind utilization. The system converts ambient mechanical energy to electricity with 400V peak voltage by charging of a 1000mF super capacitor super rapidly. Its future implementation in an array of applications aids in environment friendly clean energy production in large scale medium and the proposed design performs with an exhaustive material testing. The relation between the interfacial micro-and nano structures and the electrical performance enhancement is comparatively studied. Nanostructures are more beneficial for the effective contact area, but they are not suitable for the anti-adhesion property due to the smaller restoring force. Considering these issues, the nano-patterning is proposed for further enhancement of the effective contact area. By considering these merits of simple fabrication, outstanding performance, robust characteristic and low-cost technology, we believe that TENG can open up great opportunities not only for powering small electronics, but can contribute to large-scale energy harvesting through engineering design being complementary to solar energy in remote areas.

Keywords: triboelectric nanogenerator, wind energy, vortex design, large scale energy

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Authors: Christopher B. Obida, George A. Blackburn, James D. Whyatt, Kirk T. Semple

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In many regions of the world, especially in developing countries, river network data are outdated or completely absent, yet such information is critical for supporting important functions such as flood mitigation efforts, land use and transportation planning, and the management of water resources. In this study, a method was developed for delineating river networks using Sentinel 1 imagery. Unsupervised classification was applied to multi-temporal Sentinel 1 data to discriminate water bodies from other land covers then the outputs were combined to generate a single persistent water bodies product. A thinning algorithm was then used to delineate river centre lines, which were converted into vector features and built into a topologically structured geometric network. The complex river system of the Niger Delta was used to compare the performance of the Sentinel-based method against alternative freely available water body products from United States Geological Survey, European Space Agency and OpenStreetMap and a river network derived from a Shuttle Rader Topography Mission Digital Elevation Model. From both raster-based and vector-based accuracy assessments, it was found that the Sentinel-based river network products were superior to the comparator data sets by a substantial margin. The geometric river network that was constructed permitted a flow routing analysis which is important for a variety of environmental management and planning applications. The extracted network will potentially be applied for modelling dispersion of hydrocarbon pollutants in Ogoniland, a part of the Niger Delta. The approach developed in this study holds considerable potential for generating up to date, detailed river network data for the many countries where such data are deficient.

Keywords: Sentinel 1, image processing, river delineation, large scale mapping, data comparison, geometric network

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Authors: Altilio Rosa, Chirico Francesco, Foglia Goffredo

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In recent years, the number of Unmanned Aerial Vehicles (UAVs) has significantly increased. The rapid development of commercial and recreational drones makes them an important part of our society. Despite the growing list of their applications, these vehicles pose a huge threat to civil and military installations: detection, classification and neutralization of such flying objects become an urgent need. Radar is an effective remote sensing tool for detecting and tracking flying objects, but scenarios characterized by the presence of a high number of tracks related to flying birds make especially challenging the drone detection task: operator PPI is cluttered with a huge number of potential threats and his reaction time can be severely affected. Flying birds compared to UAVs show similar velocity, RADAR cross-section and, in general, similar characteristics. Building from the absence of a single feature that is able to distinguish UAVs and birds, this paper uses a multiple features approach where an original feature selection technique is developed to feed binary classifiers trained to distinguish birds and UAVs. RADAR tracks acquired on the field and related to different UAVs and birds performing various trajectories were used to extract specifically designed target movement-related features based on velocity, trajectory and signal strength. An optimization strategy based on a genetic algorithm is also introduced to select the optimal subset of features and to estimate the performance of several classification algorithms (Neural network, SVM, Logistic regression…) both in terms of the number of selected features and misclassification error. Results show that the proposed methods are able to reduce the dimension of the data space and to remove almost all non-drone false targets with a suitable classification accuracy (higher than 95%).

Keywords: birds, classification, machine learning, UAVs

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Authors: Norzaliza Md. Nor, Sh-Hussain Salleh, Mahyar Hamedi, Hadrina Hussain, Wahab Abdul Rahman

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Motivational factor is mainly the students’ desire to involve in learning process. However, it also depends on the goal towards their involvement or non-involvement in academic activity. Even though, the students’ motivation might be in the same level, but the basis of their motivation may differ. In this study, it focuses on the intrinsic motivational factor which student enjoy learning or feeling of accomplishment the activity or study for its own sake. The intrinsic motivational factor of students in learning mathematics and science has found as difficult to be achieved because it depends on students’ interest. In the Program for International Student Assessment (PISA) for mathematics and science, Malaysia is ranked as third lowest. The main problem in Malaysian educational system, students tend to have extrinsic motivation which they have to score in exam in order to achieve a good result and enrolled as university students. The use of electroencephalogram (EEG) signals has found to be scarce especially to identify the students’ intrinsic motivational factor in learning science and mathematics. In this research study, we are identifying the correlation between precursor emotion and its dynamic emotion to verify the intrinsic motivational factor of students in learning mathematics and science. The 2-D Affective Space Model (ASM) was used in this research in order to identify the relationship of precursor emotion and its dynamic emotion based on the four basic emotions, happy, calm, fear and sad. These four basic emotions are required to be used as reference stimuli. Then, in order to capture the brain waves, EEG device was used, while Mel Frequency Cepstral Coefficient (MFCC) was adopted to be used for extracting the features before it will be feed to Multilayer Perceptron (MLP) to classify the valence and arousal axes for the ASM. The results show that the precursor emotion had an influence the dynamic emotions and it identifies that most students have no interest in mathematics and science according to the negative emotion (sad and fear) appear in the EEG signals. We hope that these results can help us further relate the behavior and intrinsic motivational factor of students towards learning of mathematics and science.

Keywords: EEG, MLP, MFCC, intrinsic motivational factor

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Authors: Pascal U. Onu, Doris A. Ogbang, Emmanuel Okechukwu.

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Background: Plastics in their various forms have become ubiquitous in a very short space of time. This ubiquitous nature has plagued and daunted nations globally, overwhelming their ability to manage the environmental impact, especially its linkages to climate change. This has mobilized nations globally and triggered debates on the best approaches to ensure sustainability in terms of its production and utilization, as total elimination seems unrealistic. Objective: This study undertook to understand the pattern of plastic waste management, and its pollution awareness levels by the residents of the study area. Methods: Data were obtained through questionnaires designed specifically for plastic waste and qualitatively via journals and articles. Simple descriptive survey techniques with a survey population size of 300 respondents using kobo collect were employed. Results: Analysis based on disaggregated data indicated a proportionate distribution among male and female respondents (53% male and 47% female, respectively). Overall awareness levels on plastic waste's contribution to climate change, compared to its environmental impact, are reflective of a dire need for increased efforts in strengthening awareness creation, especially across gender populations and religious backgrounds. Drainage blockage topped the ranks among common problems caused by plastic waste within the area. Various plastic waste disposal methods were ranked, while pro-environmental measures for reducing the waste menace showed more willingness from males at 52%. Conclusion: These outcomes are instructive and suggest the need for renewed and increased awareness/education on the nexus of plastic pollution to climate change and also appropriate synergies/collaboration between government, private sector, and local communities, especially in the area of recycling to improve sustainability in plastic waste management.

Keywords: plastic waste, KAP, climate change, Nigeria

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Authors: Rahaf Mandura

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Background: Idiopathic intracranial hypertension (IIH) is a disorder with elevated intracranial pressure (ICP) more than 250 mm H₂O, without evidence of meningeal inflammation, space-occupying lesion, or venous thrombosis. The aim of this research is to study the clinical profile, evaluation, management, and visual outcome in a hospital-based population of IIH cases in Jeddah. Methodology: This is a retrospective observational study that included the medical records of all patients referred to neuro-ophthalmology service for evaluation of papilledema. The medical records have been reviewed from October 2018 to February 2020 at Jeddah Eye Hospital (JEH), Saudi Arabia. A total of fifty-one patients presented with papilledema in the studied period. Forty-seven patients met our inclusion criteria and were included in the study. Results: Most of the patients were females (43, 91.5%) with a mean age of presentation of 30.83±11.40 years. The most common presenting symptom was headache (40 patients, 85.1%), followed by transient visual obscuration (20 patients, 42.6%), and reduced visual acuity (15 patients, 31.9%). All 47 patients were started on medical treatment with oral acetazolamide with four patients (8.5%) shifted to topiramate because of the lack of response or intolerance to acetazolamide while four patients (8.5%) underwent lumbar-peritoneal shunt because of inadequate control of the disease despite the treatment with medical therapy. For both eyes, the change in visual acuity across all assessment points was statistically significant. Nevertheless, there were no significant changes in the visual field findings among all of the compared assessment points. Conclusion: The present study has shown that IIH-related papilledema is common in young female patients with headaches, transient visual obscurations and reduced visual acuity. Those are the commonest symptoms in our IIH population. Medical treatment of IIH is significantly efficacious and should be considered in order to enhance the prognosis of IIH-related complications. Therefore, the visual status should be frequently monitored for these patients.

Keywords: idiopathic intracranial hypertension, intracranial hypertension, papilledema, headache

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Authors: Marios Papaevripidou, Yvoni Pavlou, Zacharias Zacharia

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Embodied cognition and additional (touch) sensory channel theories indicate that physical manipulation is crucial to learning since it provides, among others, touch sensory input, which is needed for constructing knowledge. Given these theories, the use of Physical Manipulatives (PM) becomes a prerequisite for learning. On the other hand, empirical research on Virtual Manipulatives (VM) (e.g., simulations) learning has provided evidence showing that the use of PM, and thus haptic sensory input, is not always a prerequisite for learning. In order to investigate which means of experimentation, PM or VM, are required for enhancing student science learning at the kindergarten level, an empirical study was conducted that sought to investigate the impact of haptic feedback on the conceptual understanding of pre-school students (n=44, age mean=5,7) in three science domains: beam balance (D1), sinking/floating (D2) and springs (D3). The participants were equally divided in two groups according to the type of manipulatives used (PM: presence of haptic feedback, VM: absence of haptic feedback) during a semi-structured interview for each of the domains. All interviews followed the Predict-Observe-Explain (POE) strategy and consisted of three phases: initial evaluation, experimentation, final evaluation. The data collected through the interviews were analyzed qualitatively (open-coding for identifying students’ ideas in each domain) and quantitatively (use of non-parametric tests). Findings revealed that the haptic feedback enabled students to distinguish heavier to lighter objects when held in hands during experimentation. In D1 the haptic feedback did not differentiate PM and VM students' conceptual understanding of the function of the beam as a mean to compare the mass of objects. In D2 the haptic feedback appeared to have a negative impact on PM students’ learning. Feeling the weight of an object strengthen PM students’ misconception that heavier objects always sink, whereas the scientifically correct idea that the material of an object determines its sinking/floating behavior in the water was found to be significantly higher among the VM students than the PM ones. In D3 the PM students outperformed significantly the VM students with regard to the idea that the heavier an object is the more the spring will expand, indicating that the haptic input experienced by the PM students served as an advantage to their learning. These findings point to the fact that PMs, and thus touch sensory input, might not always be a requirement for science learning and that VMs could be considered, under certain circumstances, as a viable means for experimentation.

Keywords: haptic feedback, physical and virtual manipulatives, pre-school science learning, science experimentation

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Authors: Vladimir Hovhannisyan, Chen Yuan Dong

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Recently nanoparticles (NPs) have been introduced in biomedicine as effective agents for cancer-targeted drug delivery and noninvasive tissue imaging. The most important requirements to these agents are their non-toxicity, biocompatibility and stability. In view of these criteria, the zeolite (ZL) nanoparticles (NPs) may be considered as perfect candidates for biomedical applications. ZLs are crystalline aluminosilicates consisting of oxygen-sharing SiO4 and AlO4 tetrahedral groups united by common vertices in three-dimensional framework and containing pores with diameters from 0.3 to 1.2 nm. Generally, the behavior and physical properties of ZLs are studied by SEM, X-ray spectroscopy, and AFM, whereas optical spectroscopic and microscopic approaches are not effective enough, because of strong scattering in common ZL bulk materials and powders. The light scattering can be reduced by using of ZL NPs. ZL NPs have large external surface area, high dispersibility in both aqueous and organic solutions, high photo- and thermal stability, and exceptional ability to adsorb various molecules and atoms in their nanopores. In this report, using multiphoton microscopy and nonlinear spectroscopy, we investigate nonlinear optical properties of clinoptilolite type of ZL micro- and nanoparticles with average diameters of 2200 nm and 240 nm, correspondingly. Multiphoton imaging is achieved using a laser scanning microscope system (LSM 510 META, Zeiss, Germany) coupled to a femtosecond titanium:sapphire laser (repetition rate- 80 MHz, pulse duration-120 fs, radiation wavelength- 720-820 nm) (Tsunami, Spectra-Physics, CA). Two Zeiss, Plan-Neofluar objectives (air immersion 20×∕NA 0.5 and water immersion 40×∕NA 1.2) are used for imaging. For the detection of the nonlinear response, we use two detection channels with 380-400 nm and 435-700 nm spectral bandwidths. We demonstrate that ZL micro- and nanoparticles can produce nonlinear optical response under the near-infrared femtosecond laser excitation. The interaction of hypericine, chlorin e6 and other dyes with ZL NPs and their photodynamic activity is investigated. Particularly, multiphoton imaging shows that individual ZL NPs particles adsorb Zn-tetraporphyrin molecules, but do not adsorb fluorescein molecules. In addition, nonlinear spectral properties of ZL NPs in native biotissues are studied. Nonlinear microscopy and spectroscopy may open new perspectives in the research and application of ZL NP in biomedicine, and the results may help to introduce novel approaches into the clinical environment.

Keywords: multiphoton microscopy, nanoparticles, nonlinear optics, zeolite

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Authors: T. Walczak, J. K. Grabski, P. Fritzkowski, M. Stopa

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Objectives of the study are i) to perform numerical simulations that permit an analysis of the dynamics of subretinal fluid when an implant has induced scleral intussusception and ii) assess the impact of the physical parameters of the model on the flow rate. Computer simulations were created using finite element method (FEM) based on a model that takes into account the interaction of a viscous fluid (subretinal fluid) with a hyperelastic body (retina). The purpose of the calculation was to investigate the dependence of the flow rate of subretinal fluid through a hole in the retina on different factors such as viscosity of subretinal fluid, material parameters of the retina, and the offset of the implant from the retina’s hole. These simulations were performed for different speeds of eye movement that reflect the behavior of the eye when reading, REM, and saccadic movements. Similar to other works in the field of subretinal fluid flow, it was assumed stationary, single sided, forced fluid flow in the considered area simulating the subretinal space. Additionally, a hyperelastic material model of the retina and parameterized geometry of the considered model was adopted. The calculations also examined the influence the direction of the force of gravity due to the position of the patient’s head on the trend of outflow of fluid. The simulations revealed that fluid outflow from the retina becomes significant with eyeball movement speed of 100°/sec. This speed is greater than in the case of reading but is four times less than saccadic movement. The increase of viscosity of the fluid increased beneficial effect. Further, the simulation results suggest that moderate eye movement speed is optimal and that the conventional prescription of the avoidance of routine eye movement following retinal detachment surgery should be relaxed. Additionally, to verify numerical results, some calculations were repeated with use of meshless method (method of fundamental solutions), which is relatively fast and easy to implement. The paper has been supported by 02/21/DSPB/3477 grant.

Keywords: CFD simulations, FEM analysis, meshless method, retinal detachment

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Authors: Anita Lazurko, Laszlo Pinter, Jeremy Richardson

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Uncertain climate projections, multiple possible development futures, and a financing gap create challenges for water infrastructure decision making. In contrast to conventional predict-plan-act methods, an emerging decision paradigm that enables social-ecological resilience supports decisions that are appropriate for uncertainty and leverage social, ecological, and economic multifunctionality. Concurrently, water infrastructure project finance plays a powerful role in sustainable infrastructure development but remains disconnected from discourse in socio-ecological resilience. At the time of research, a project to transfer water from Lesotho to Botswana through South Africa in the Orange-Senqu River Basin was at the pre-feasibility stage. This case was analysed through documents and interviews to investigate how uncertainty and multifunctionality are conceptualised and considered in decisions for the resilience of water infrastructure and to explore bridging concepts that might allow project finance to better enable socio-ecological resilience. Interviewees conceptualised uncertainty as risk, ambiguity and ignorance, and multifunctionality as politically-motivated shared benefits. Numerous efforts to adopt emerging decision methods that consider these terms were in use but required compromises to accommodate the persistent, conventional decision paradigm, though a range of future opportunities was identified. Bridging these findings to finance revealed opportunities to consider a more comprehensive scope of risk, to leverage risk mitigation measures, to diffuse risks and benefits over space, time and to diverse actor groups, and to clarify roles to achieve multiple objectives for resilience. In addition to insights into how multiple decision paradigms interact in real-world decision contexts, the research highlights untapped potential at the juncture between socio-ecological resilience and project finance.

Keywords: socio-ecological resilience, finance, multifunctionality, uncertainty

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Authors: Qirat Naz, Abasiokpon Udoakah

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In developed countries, global migration is diversifying. The minority ethnic population, including refugees and asylum seekers who, fled their home countries due to war, terrorism, oppression, or natural disasters, and returning home is dangerous for them. They need sanctuary and peaceful environment in host countries. They begin the process of acculturation, in which a person adopts the social mores and behavioral patterns of the dominant culture, yet they still have unique multicultural needs that the dominant society fails to address. The aim of this research is to provide a holistic understanding of the living experiences of a minority population, particularly migrants, including asylum seekers and refugees, in the health and social care system of South Wales. The purpose of this study is to investigate three research objectives: the multicultural health care needs of minorities, as well as the barriers to seeking health and social care facilities. There are Welsh policies for promoting cultural competence in the health and social care sectors; this research will explore the implications and impact of these policies on the target population. This research study will be conducted using qualitative research methods, tools, and techniques. This research is an inductive approach to coming up with a grounded theory. The sample will be divided into two groups: migrants and professionals providing any kind of services to migrants; each group will contain 30 participants. Interpretive phenomenological analysis would be utilized during the process of coding and developing the main themes of this research. The positionality of the researcher would be minimized by unloaded and open-ended questions, researcher’s work experience in research, continuous evaluation of her positionality, daily base reflection of fieldwork and seeking the help of male and female gatekeepers. The research findings would be based on emic perspective, and by documenting the emic perspective of minorities, this research will contribute to the knowledge of appropriate channels, including organizations, academics, and policymakers, to discover possible solutions and coping mechanisms to deal with the challenges and meet the multicultural demands of minorities. This research will provide a more in-depth understanding of minorities and will help to promote the diversity of health and social care in South Wales.

Keywords: migration, migrants, cultural competence, cultural barriers, healthcare challenges

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Authors: Michael Rudolph, Evans Muchesa, Katiya Yassim, Venkatesha Prasad

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Input-intensive production systems characterise industrial agriculture as an unsustainable means to address food and nutrition security and sustainable livelihoods. There is extensive empirical evidence that supports the diversification and reorientation of industrial agriculture and that incorporates ecological practices viewed as essential for achieving balanced and productive farming systems. An agroecological farming system is a viable alternative approach that can improve food production, especially for the most vulnerable communities and households. Furthermore, substantial proof and supporting evidence show that such a system holds the key to increasing dietary diversity at the local level and reducing the multiple health and environmental risks stemming from industrial agriculture. This paper, therefore, aims to demonstrate the benefits of the agroecology food system through an evidenced-based approach that shows how the broader agricultural network structures can play a meaningful role, particularly for impoverished households in today’s reality. The methodology is centered on a structured literature review that analyses urban agriculture, agroecology, and food insecurity. Notably, ground-truthing, practical experiences, and field observation of agroecological farming were deployed. This paper places particular emphasis on the practical application of the agroecological approach in urban and peri-urban settings. Several evaluation reports on local and provincial initiatives clearly show that very few households engage in food gardens and urban agriculture. These households do not make use of their backyards or nearby open spaces for a number of reasons, such as stringent city by-laws, restricted access to land, little or no knowledge of innovative or alternative farming practices, and a general lack of interest. Furthermore, limited resources such as water and energy and lack of capacity building and training implementation are additional constraints that are hampering small scale food gardens and farms in other settings. The Agroecology systems approach is viewed as one of the key solutions to tackling these problems.

Keywords: agroecology, water-energy-food nexus, sutainable development goals, social, environmental and economc impact

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Authors: Shady Adib, Vladimir Vinogradov, Peter Gosling

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Digital Twin (DT) technology is a new technology that appeared in the early 21st century. The DT is defined as the digital representation of living and non-living physical assets. By connecting the physical and virtual assets, data are transmitted smoothly, allowing the virtual asset to fully represent the physical asset. Although there are lots of studies conducted on the DT concept, there is still limited information about the ability of the DT models for monitoring and detecting unexpected changes in structural behaviour in real time. This is due to the large computational efforts required for the analysis and an excessively large amount of data transferred from sensors. This paper aims to develop the DT concept to be able to detect the abnormal changes in structural behaviour in real time using advanced modelling techniques, deep learning algorithms, and data acquisition systems, taking into consideration model uncertainties. finite element (FE) models were first developed offline to be used with a reduced basis (RB) model order reduction technique for the construction of low-dimensional space to speed the analysis during the online stage. The RB model was validated against experimental test results for the establishment of a DT model of a two-dimensional truss. The established DT model and deep learning algorithms were used to identify the location of damage once it has appeared during the online stage. Finally, the RB model was used again to identify the damage severity. It was found that using the RB model, constructed offline, speeds the FE analysis during the online stage. The constructed RB model showed higher accuracy for predicting the damage severity, while deep learning algorithms were found to be useful for estimating the location of damage with small severity.

Keywords: data acquisition system, deep learning, digital twin, model uncertainties, reduced basis, reduced order model

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Authors: Balthazar Temu, Zhao Yan, Bogdan-Petrin Ratiu, Sang Soon Oh, Qiang Li

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Photonic crystal surface emitting lasers (PCSELs) has recently become an area of active research because of the advantages these lasers have over the edge emitting lasers and vertical cavity surface emitting lasers (VCSELs). PCSELs can emit laser beams with high power (from the order of few milliwatts to Watts or even tens of Watts) which scales with the emission area while maintaining single mode operation even at large emission areas. Most PCSELs reported in the literature are air-hole based, with only few demonstrations of nanowire based PCSELs. We previously reported an optically pumped, nanowire based PCSEL operating in the O band by using the honeycomb lattice. The nanowire based PCSELs have the advantage of being able to grow on silicon platform without threading dislocations. It is desirable to extend their operating wavelength to C band to open more applications including eye-safe sensing, lidar and long haul optical communications. In this work we first analyze how the lattice constant , nanowire diameter, nanowire height and side length of the hexagon in the honeycomb pattern can be changed to increase the operating wavelength of the honeycomb based PCSELs to the C band. Then as an attempt to make our device electrically pumped, we present the finite-difference time-domain (FDTD) simulation results with metals on the nanowire. The results for different metals on the nanowire are presented in order to choose the metal which gives the device with the best quality factor. The metals under consideration are those which form good ohmic contact with p-type doped InGaAs with low contact resistivity and decent sticking coefficient to the semiconductor. Such metals include Tungsten, Titanium, Palladium and Platinum. Using the chosen metal we demonstrate the impact of thickness of the metal for a given nanowire height on the quality factor of the device. We also investigate how the height of the nanowire affects the quality factor for a fixed thickness of the metal. Finally, the main steps in making the practical device are discussed.

Keywords: designing nanowire PCSEL, designing PCSEL on silicon substrates, low threshold nanowire laser, simulation of photonic crystal lasers.

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Authors: Pravin Kumar, Rajendra K. Singh, Prabhakar Singh

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A widespread research work on Mo-based double perovskite systems has been reported as a potential application for electrode materials of solid oxide fuel cells. Mo-based double perovskites studied in form of B-site ordered double perovskite materials, with general formula A₂B′B″O₆ structured by alkaline earth element (A = Sr, Ca, Ba) and heterovalent transition metals (B′ = Fe, Co, Ni, Cr, etc. and B″ = Mo, W, etc.), are raising a significant interest as potential mixed ionic-electronic conductors in the temperature range of 500-800 °C. Such systems reveal higher electrical conductivity, particularly those assigned in form of Sr₂CoMoO₆₋δ (M = Mg, Mn, Fe, Co, Ni, Zn etc.) which were studied in different environments (air/H₂/H₂-Ar/CH₄) at an intermediate temperature. Among them, the Sr₂CoMoO₆₋δ system is a potential candidate as an anode material for solid oxide fuel cells (SOFCs) due to its better electrical conductivity. Therefore, Sr₂CoMoO₆₋δ (SCM) system with La-doped on Sr site has been studied to discover the structural and electrical properties. The double perovskite system Sr₂CoMoO₆₋δ (SCM) and doped system Sr₂-ₓLaₓCoMoO₆₋δ (SLCM, x=0.04) were synthesized by the citrate-nitrate combustion synthesis route. Thermal studies were carried out by thermo-gravimetric analysis. Phase justification was confirmed by powder X-ray diffraction (XRD) as a tetragonal structure with space group I4/m. A minor phase of SrMoO₄ (s.g. I41/a) was identified as a secondary phase using JCPDS card no. 85-0586. Micro-structural investigations revealed the formation of uniform grains. The average grain size of undoped (SCM) and doped (SLCM) compositions was calculated by a linear intercept method and found to be ⁓3.8 μm and 2.7 μm, respectively. The electrical conductivity of SLCM is found higher than SCM in the air within the temperature range of 200-600 °C. SLCM system was also measured in reducing atmosphere (pure H₂) in the temperature range 300-600 °C. SLCM has been showed the higher conductivity in the reducing atmosphere (H₂) than in air and therefore it could be a promising anode material for SOFCs.

Keywords: double perovskite, electrical conductivity, SEM, XRD

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