14,089 research outputs found

    Enhancement of speed and efficiency of an Internet based gear design optimisation

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    An internet-based gear design optimisation program has been developed for geographically dispersed teams to collaborate over the internet. The optimisation program implements genetic algorithm. A novel methodology is presented that improves the speed of execution of the optimisation program by integrating artificial neural networks into the system. The paper also proposes a method that allows an improvement to the performance of the back propagation-learning algorithm. This is done by rescaling the output data patterns to lie slightly below and above the two extreme values of the full range neural activation function. Experimental tests show the reduction of execution time by approximately 50%, as well as an improvement in the training and generalisation errors and the rate of learning of the network

    What surface maximizes entanglement entropy?

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    For a given quantum field theory, provided the area of the entangling surface is fixed, what surface maximizes entanglement entropy? We analyze the answer to this question in four and higher dimensions. Surprisingly, in four dimensions the answer is related to a mathematical problem of finding surfaces which minimize the Willmore (bending) energy and eventually to the Willmore conjecture. We propose a generalization of the Willmore energy in higher dimensions and analyze its minimizers in a general class of topologies Sm×SnS^m\times S^n and make certain observations and conjectures which may have some mathematical significance.Comment: 21 pages, 2 figures; V2: typos fixed, Refs. adde

    Nonlocal mixing of supercurrents in Josephson ballistic point contact

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    We study coherent current states in the mesoscopic superconducting weak link simultaneously subjected to the order parameter phase difference on the contact and to the tangential to the junction interface superfluid velocity in the banks. The Josephson current-phase relation controlled by the external transport current is obtained. At phase difference close to pi the nonlocal nature of the Josephson phase-dependent current results in the appearance of two vortexlike states in the vicinity of the contact.Comment: 4 pages, 6 figures; to be published in Phys. Rev. B; e-mail: [email protected]

    Effect of culture on acceptance of telemedicine in Middle Eastern countries: Case study of Jordan and Syria

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    © Mary Ann Liebert, INC.We investigated issues that affect the use and adoption of telemedicine in Middle Eastern countries, taking the Hashemite Kingdom of Jordan and the Syrian Arab Republic as case studies. Our study is based on interviews with key stakeholders (including doctors, technicians, engineers, and decision makers) and questionnaires administered to key stakeholders (including patients), ensuring opinion was gained from people from a full range of backgrounds and roles in the healthcare system. We found doctor and patient resistance was a major issue preventing the adoption of telemedicine in both countries, followed by poor infrastructure, lack of funding, and lack of information technology training. Our research identifies that culture is a greater issue than technical matters for the adoption of telemedicine in Middle Eastern countries. Based on our preliminary results we developed a guideline framework for each country that might be applied to telemedicine projects at the pre-implementation phase. The proposed guideline framework was validated through a return visit to the stakeholders and seeking further opinion

    Prevalence of exclusive breastfeeding and its determinants in first 6 months of life: A prospective study

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    Background: Exclusive breastfeeding for first 6 months of life is recommended under Infant and Young Child Feeding practices in India. The objective of present study was to estimate the prevalence of exclusive breastfeeding during first 6 months of life of babies and to identify factors that interfere with the practice in the study area. Methods: A prospective cohort of 462 women who delivered at maternity unit of Government Medical College & Hospital, Rajkot, which is a tertiary care centre for the district, was studied. Data collection was done at hospital as well as during home visits of babies at 1, 3 and 6 months. Factors related to cessation of breastfeeding were analyzed using univariate, bivariate and multivariate analysis. Results: All 462 mothers reported breastfeeding their newborns. Prevalence of exclusive breastfeeding reported at 3 months was 97% which declined to 62% by 6 months of age of infants. Bivariate analysis revealed no significant association between interruption of exclusive breastfeeding before 6 months of age and various demographic, socioeconomic, maternal and infant characteristics. Multivariate analysis by logistic regression demonstrated no association between discontinuation of exclusive breastfeeding and socioeconomic status, maternal education and maternal age, number of antenatal visits, maternal employment and initiation of breastfeeding after delivery. Conclusion: Exclusive breastfeeding prevalence rate found higher than at national level indicating better feeding practices in these part of India. Also, factors classically considered as supportive for breastfeeding had shown no association with breastfeeding pattern in present study

    Developing an environmentally appropriate, socially acceptable and gender-sensitive technology for safe-water supply to households in arsenic affected areas in rural Bangladesh

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    To confront the arsenic crisis in Bangladesh, several options for a safe water supply in the rural As-affected areas are available. Most of these options have shown a minimum scope to mitigate arsenic-related risks because of their poor performance and non-acceptability by the rural households. In this research, therefore, the development of an appropriate technology for an As-free, safe drinking water supply is considered from a local perspective and a societal context. To achieve the goal and objectives of this research, four research questions were formulated (Chapter 1). The first research question is about the technological and socio-economic performance of community-based pipeline water supply systems that use deep aquifers. The second question deals with available and currently implemented household-level arsenic removal technologies in rural Bangladesh. The third addresses the weaknesses, limitations, strengths and advantages of the technologies in terms of a number of technological, social, economic and gender indicators. Fourth, the question is posed of the most promising arsenic removal option for rural house¬holds in terms of its techno¬logical performance and social acceptability and suitability from a gender perspective. The occurrence of As in the Delta region is of geochemical origin and its distribution in the groundwater has distinct regional patterns and depth trends. An overview of the arsenic problem in Bangladesh is given in Chapter 2. The overall objective of the research was to develop a socially appropriate and gender-sensitive household-level As removal filter. Technical, socio-economic and cultural aspects were incorporated in this research to assess the development of a sustainable innovation through multi- and interdisciplinary approaches. The technical validation of the systems was carried out through laboratory-based research, to address the efficiency, robustness, operational and maintenance convenience, safety and viability of the technology. For the social research, the model by Spaargaren and Van Vliet (2000) was adjusted to address the filter’s suitability in terms of lifestyle, domestic time-space structures, affordability, standards of comfort, cleanliness, convenience and modes of provision. In addition, I also considered the household resource-based affordability during the operation and maintenance phase, in terms of a socio-technological and gender perspective. A conceptual model was developed to guide the research and to answer the research questions (Chapter 1). The socio-economic data on the main concepts of this research work were collected through a survey (Appendix 2). In this research, a synthesis of knowledge resulting from disciplinary, open-ended collaboration and local perspectives is achieved. Such a transdisciplinary research approach ensures an integration of knowledge through the participation of a variety of stakeholders, including end users, and mutual learning between the different stakeholders, such as users of the Modified Garnet Homemade Filter (MGH Filter), caretakers, village committees, implementing organizations and donors, users of water, households, and women. The community–based piped water supply in Bangladesh There are several alternative sources to get safe and As-free drinking water in Bangladesh. A community-based piped water supply system using deep aquifers is one of them. In this research, three community-based piped water supply systems were compared to evaluate their technological and economic sustainability, the sustainability of using deep aquifers for the long term, and the social and gender appropriateness of the systems, based on the users’ perspective (Chapter 4). The technical performance of the three systems in different geological conditions was found satisfactory in terms of their efficacy, water quality, adequacy of the water supply, and operations and maintenance. The water is As- and Fe-free and is of good taste. The concentration of As is below the limiting range of drinking water in Bangladesh (50µgL-1As), as well as within the WHO and new EPA standards (10µgL-1As). The sustainable use of deep aquifers for a longer period is a serious issue. To address the sustainability, hydro-geological factors need to be well understood. Overextraction of water from deep aquifers could induce a downward migration of dissolved As and permanently destroy the deep resource. Only one system is practicing chlorination to disinfect the water in the overhead tank, while the other two systems do not have such a provision. However, the field data reveal that the three systems are technologically acceptable and do not require disposal of contaminated sludge. The women who are using one of the three water supply systems are satisfied about the water supply systems. They think the systems reliable in their delivery of adequate water and convenient and comfortable for the women users. Women can get water close to their house, which saves collection time and a physical burden. The appointed caretakers are operating the systems efficiently, including maintenance and the collection of the monthly bill from the beneficiaries. The economical sustainability seems to be satisfactory, provided the initial costs are subsidized by external financial assistance with only a little contribution from the communities, which varies from five to seven percent of the total capital cost. The community participation in sharing the installation cost for the system and the monthly bill are fixed, based on the economical condition of the households. However, a drawback of the community-based piped water system is disruption of the system due to its sensitivity to power failure, which is a big problem in Bangladesh. Other shortcomings are the limitations to extend the system to meet the increasing demand of the village people. On the long term, economical sustainability factors need to be considered, such as the availability of funds and the participation of the users in the system’s management, which were absent in all three systems. Currently available and implemented household-level arsenic removal technologies The application of arsenic removal technologies to provide safe drinking water in rural areas plays a vital role where other, alternative options and safe aquifers are not easily available and where community-based pipeline water supply systems are not feasible. In this research, physico-chemical and biological as well as conventional techniques for the removal of arsenic were reviewed (Chapter 5). Based on literature, an inventory was carried out of 40 available and currently implemented technologies at the household level in terms of their arsenic removal efficiency, cost and users’ acceptance. All the technologies remove As from the water to a limited extent. Therefore, there is scope for further development of these technologies. A multiple-criteria analysis (MCA) approach was applied to select a technology for the further development of an appropriate arsenic removal filter for household-level use. In the research, based on the integrated assessments, the MCA-GARNET technology was selected for further development. An assessment of the performances of the three governmentally certified arsenic removal technologies for rural household use was carried out (Chapter 5). This research concludes that the government’s investments in an improved water supply so far have failed to meet the needs of the poor villagers, because they are not able to buy the costly Alcan and Read-F filters. Even the relatively cheap Sono filter proved to be unaffordable for the poorest. Furthermore, assessing the As removal efficiency and life span of these filters is difficult at this preliminary stage, and so is predicting how the disposal of the spent filter materials will be carried out by the users. The As leaching from the sludge/waste generated by the three treatment processes is dependent on the type of removal mechanism and the ultimate sludge disposal methods. Development of a chemical-free arsenic removal technology for household use In this research, by the active participation of potential end users and other stakeholders, I have included local knowledge and social and gender perspectives in the process of the development of an innovative As removal filter (MGH filter) (Chapter 6). The MGH filter efficiency and breakthrough point were studied at different operational variables, such as filter bed thickness, types of filter media and flow rate. The toxicity of the spent material was addressed by a TCLP test. The developed filter meets the Bangladesh standard for arsenic in drinking water (50µgL-1). It can reduce the arsenic concentrations of the shallow tube well water samples from 160-959µgL-1 to 0-50µgL-1. It can also remove bacteriological contamination in terms of total coliform and fecal coliform counts from >500 to 0 cfu/100 mL-1 . The filter consists of two-bucket filters in series, each with three filter material layers of 14 cm thickness each, containing sand, brick chip and sand (Figure 7.1). The first-class brick chips of 1.3 cm size and Sylhet coarse sands were found to be the most efficient. The major advantage of this unit is that it does not require any daily addition of chemicals and can be operated at a high flow rate. It needs to be cleaned regularly to prevent bacterial contamination, while its maintenance requires treatment with bleaching powder at 15-day intervals. The filter is cost–effective and viable; the investments and operational cost are about € 10.8-13.4 and € 0.11-0.14 per 100 liters of treated water, respectively. In this research, a multi-perspective and participatory socio-technological assessment of the filter’s performance during the field level application was carried out in two phases: the trial phase during March 2008 and the evaluation phase during July 2008 (Chapter 7). Eight MGH filters were distributed among eight households in the research area in Kumarbhog. In this research, the multi-perspective assessment comprised interdisciplinary and transdisciplinary approaches to evaluate the performance of the filters for household use. Both quantitative and qualitative methods of data collection and analysis were used. The suitability and acceptability of the filters were evaluated through systematic observation, interviewing, FGDs and eight case studies of the filter users. The compatibility and appropriate¬ness of the filter were viewed from a gender pers¬pective, since access to safe water is an important practical gender need of women, directly related to their domestic and reproductive role. Women of the selected eight rural households adopted the technology and ran the filters successfully during the trial phase. As elsewhere in developing countries, in Bangladesh too, rural women are the managers of water for household use. They hardly participate in income generation. The male household head controls the allocation of household income and expenditures, which caused problems when women wanted to re-install their filter. The household survey revealed that sometimes, women cannot be bothered to fetch safe water from far away and, instead, drink the con¬taminated water from their own shallow tube wells. Having the appliance inside the house complied well with the social norms and religious restrictions (purdah) that women have to abide by. In these circumstances, the MGH filter was eagerly accepted by the eight households, because it reduced women’s social and physical burden to fetch As-free, safe water far from their home. In the evaluation phase, some filters were unused because the women could not persuade their husbands to purchase the necessary filter bed materials. During the evaluation phase, the performance of the filters declined compared to the trial phase, because not all users followed the instructions on its operation and maintenance, such as proper chlorination and clean¬liness of the appliance. Disposal of spent filter material was carried out in different ways by the MGH filter users, but more investigation is needed to enable an environmentally friendly disposal of the As-rich sludge. A new filter system has been developed that can be used by women at the household level. In terms of the simplicity of construction, operation and maintenance, As removal efficiency, and bacterial removal efficiency, its technical performance is good. It is also very cost-effective. However, because such a system always needs to be completely safe for producing drinking water, on the long term as well as under local and household conditions other than those investigated in this research project, further evaluation and additional research will be necessary. In this research, the filter was field-tested under controlled conditions for a month and evaluated after three months. Considering the need for arsenic treatment options in Bangladesh and other developing countries, further research on the performance of the MGH technology could have important positive implications for a safe water supply. Therefore, to allow for seasonality, the MGH filter should be pilot-tested and properly developed over a period of at least a year, in different geographical conditions. A social, economic and technical validation of the MGH filter should be included in the pilot-testing in different parts of the country by applying interdisciplinary and transdisciplinary approaches. Because women are the collectors and managers of drinking water, doing the validation in different parts of the country allows for variation in women’s roles and position and the local socio-cultural context. The MGH filter should be submitted for certification by the government of Bangladesh after further testing and development. The technological principle of the MGH filter may be used to research and develop a community-based low-cost arsenic removal water supply system in rural areas. The results of this research testify to the feasibility of a gender-sensitive, socially acceptable and technologically sound, sustainable solution to the problem of the As contamination of water for household use in rural areas in Bangladesh. <br/

    Mesoscopic multiterminal Josephson structures: I. Effects of nonlocal weak coupling

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    We investigate nonlocal coherent transport in ballistic four-terminal Josephson structures (where bulk superconductors (terminals) are connected through a clean normal layer, e.g., a two-dimensional electron gas). Coherent anisotropic superposition of macroscopic wave functions of the superconductors in the normal region produces phase slip lines (2D analogs to phase slip centres) and time-reversal symmetry breaking 2D vortex states in it, as well as such effects as phase dragging and magnetic flux transfer. The tunneling density of local Andreev states in the normal layer was shown to contain peaks at the positions controlled by the phase differences between the terminals. We have obtained general dependence of these effects on the controlling supercurrent/phase differences between the terminals of the ballistic mesoscopic four-terminal SQUID.Comment: 18 pages, 11 figure
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