5,401 research outputs found

    Numerical Experimental Investigation of Solidification Thickness around Cylindrical Surfaces for HVAC Cold Storage Systems

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    Thermal Ice Storage System (TISS) is an innovative way of storing night-time off-peak energy for daytime peak USAge. In many locations, demand for electrical power peaks during summer time. Air-conditioning equipment are the main reason accounting for as much as half of the power demand during the hot mid-day hours when electricity is most expensive. Since utilities have spare electrical generating capacity at night, electricity generated during this ldquo;off-peakrdquo; is much less expensive. In this research a numerical model for Latent Heat Storage (LHS) cylindrical tank has been obtained from a numerical package, ANSYS software ver. 15, and compared to an experimental data gathered from similar tank. The data showed good agreement with the experimental data with an error of 9%. The numerical model can be used to estimate ice thickness and tank geometries for any future work

    On-Line Monitoring for Temporal Logic Robustness

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    In this paper, we provide a Dynamic Programming algorithm for on-line monitoring of the state robustness of Metric Temporal Logic specifications with past time operators. We compute the robustness of MTL with unbounded past and bounded future temporal operators MTL over sampled traces of Cyber-Physical Systems. We implemented our tool in Matlab as a Simulink block that can be used in any Simulink model. We experimentally demonstrate that the overhead of the MTL robustness monitoring is acceptable for certain classes of practical specifications

    Sinorhizobium meliloti requires a cobalamin-dependent ribonucleotide reductase for symbiosis with its plant host

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    Vitamin B[subscript 12] (cobalamin) is a critical cofactor for animals and protists, yet its biosynthesis is limited to prokaryotes. We previously showed that the symbiotic nitrogen-fixing alphaproteobacterium Sinorhizobium meliloti requires cobalamin to establish a symbiotic relationship with its plant host, Medicago sativa (alfalfa). Here, the specific requirement for cobalamin in the S. meliloti–alfalfa symbiosis was investigated. Of the three known cobalamin-dependent enzymes in S. meliloti, the methylmalonyl CoA mutase (BhbA) does not affect symbiosis, whereas disruption of the metH gene encoding the cobalamin-dependent methionine synthase causes a significant defect in symbiosis. Expression of the cobalamin-independent methionine synthase MetE alleviates this symbiotic defect, indicating that the requirement for methionine synthesis does not reflect a need for the cobalamin-dependent enzyme. To investigate the function of the cobalamin-dependent ribonucleotide reductase (RNR) encoded by nrdJ, S. meliloti was engineered to express an Escherichia coli cobalamin-independent (class Ia) RNR instead of nrdJ. This strain is severely defective in symbiosis. Electron micrographs show that these cells can penetrate alfalfa nodules but are unable to differentiate into nitrogen-fixing bacteroids and, instead, are lysed in the plant cytoplasm. Flow cytometry analysis indicates that these bacteria are largely unable to undergo endoreduplication. These phenotypes may be due either to the inactivation of the class Ia RNR by reactive oxygen species, inadequate oxygen availability in the nodule, or both. These results show that the critical role of the cobalamin-dependent RNR for survival of S. meliloti in its plant host can account for the considerable resources that S. meliloti dedicates to cobalamin biosynthesis.National Institutes of Health (U.S.) (Grant GM31010)National Institutes of Health (U.S.) (Grant K99 GM083343)Jane Coffin Childs Memorial Fund for Medical Research (Postdoctoral Fellowship

    Empirical Investigation on Agile Methods Usage: Issues Identified from Early Adopters in Malaysia

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    Agile Methods are a set of software practices that can help to produce products faster and at the same time deliver what customers want. Despite the benefits that Agile methods can deliver, however, we found few studies from the Southeast Asia region, particularly Malaysia. As a result, less empirical evidence can be obtained in the country making its implementation harder. To use a new method, experience from other practitioners is critical, which describes what is important, what is possible and what is not possible concerning Agile. We conducted a qualitative study to understand the issues faced by early adopters in Malaysia where Agile methods are still relatively new. The initial study involves 13 participants including project managers, CEOs, founders and software developers from seven organisations. Our study has shown that social and human aspects are important when using Agile methods. While technical aspects have always been considered to exist in software development, we found these factors to be less important when using Agile methods. The results obtained can serve as guidelines to practitioners in the country and the neighbouring regions

    Binary optical communication in single-mode and entangled quantum noisy channels

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    We address binary optical communication in single-mode and entangled quantum noisy channels. For single-mode we present a systematic comparison between direct photodetection and homodyne detection in realistic conditions, i.e. taking into account the noise that occurs both during the propagation and the detection of the signals. We then consider entangled channels based on twin-beam state of radiation, and show that with realistic heterodyne detection the error probability at fixed channel energy is reduced in comparison to the single-mode cases for a large range of values of quantum efficiency and noise parameters

    Assessment of Microbiological Quality of Fura Da Nono Produced in Kebbi State, Nigeria

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    Fura da Nono is a nutritious and refreshing drink made from fermented milk and ground millet grains. In this study, the microbiology of traditional and small-scale industrial production of Fura da Nono in Birnin Kebbi and Jega was investigated. Samples of Fura da Nono were collected from Birnin Kebbi emir’s palace, Mini Factory JEGA and a local hawker in Jega. Food borne and spoilage pathogens were identified based on their colonial morphology, gram staining reaction and series of biochemical tests. Viable colony counts, coliform test, fungal analysis and pH test were also conducted. The results revealed the highest average count of 1.25Ă—108 cfu/ml in the samples  collected from local hawker while Birnin Kebbi emir’s palace had the lowest average count of 8.3Ă—105 cfu/ml. The bacteria identified in Fura da Nono were Staphylococcus aureus, Salmonella spp, Lactobacillus plantarum and Escherichia coli. The fungi isolated were  Aspergillus flavus, Aspergillus niger and Saccharomyces cerevisiae. The highest pH (6.8) was recorded in the sample obtained from local hawker and the lowest (3.1) from the Birnin Kebbi emir’s palace. The study showed the presence of food borne and spoilage pathogens in Fura da Nono which indicates poor hygienic practices during production. Therefore, in order to produce commercial Furada Nono either at large or small-scale quantity, it is necessary to improve the acceptability, microbiological stability and hygiene of the product

    Integration of TTF, UTAUT, and ITM for mobile Banking Adoption

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    The introduction of mobile banking facility has enabled customers to carry out banking transactionswith the use of smartphones and other handheld devices from anywhere. It has become a luxurious and exclusive method of online payments. The recent growth of telecommunication sector and a tremendous increase in mobile USAge has opened new doors for sparking future of banking sector industry. The following research is aimed to find out the mobile banking adoption attitudes with the integration of TTF, UTAUT,and ITM models

    A review of system dynamics models applied in transportation

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    It is 20 years since Abbas and Bell [1994. “System Dynamics Applicability to Transportation Modeling.” Transportation Research Part A 28 (5): 373–390] evaluated the strengths and weaknesses of system dynamics (SD) as an approach for modelling in the transportation area. They listed 12 advantages of the approach and in particular suggested it was well suited to strategic issues and that it could provide a useful tool for supporting policy analysis and decision-making in the transport field. This paper sets out a review of over 50 peer-reviewed journal papers since 1994 categorising them by area of application and providing a summary of particular insights raised. The fields of application include the take-up of alternate fuel vehicles, supply chain management affecting transport, highway maintenance, strategic policy, airport infrastructure and airline business cycles and a set of emerging application areas. The paper concludes with recommendations for future application of the SD approach
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