1,909 research outputs found

    Performance Assessment of Solar-Transformer-Consumption System Using Neural Network Approach

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    الطاقة الشمسية هي واحدة من الطاقة المتجددة التي لا حصر لها في توليد الطاقة لبيئة خضراء ونظيفة وصحية. تمتص الألواح الشمسية المكونة من طبقة السيليكون طاقة الشمس وتتحول إلى كهرباء بواسطة عاكس خارج الشبكة. نقل الكهرباء يتم إما من هذا العاكس أو من المحول، التي تستهلكها وحدة (وحدات) الاستهلاك المتاحة للأغراض السكنية أو الاقتصادية. الشبكة العصبية الاصطناعية هي أساس الذكاء الاصطناعي وتحل العديد من المشاكل المعقدة التي يصعب من خلال الأساليب الإحصائية أو من قبل البشر. في ضوء ذلك، فإن الغرض من هذا العمل هو تقييم أداء نظام الطاقة الشمسية - المحولات - الاستهلاك (STC). قد يكون النظام في حالة انهيار كامل بسبب فشل كل من النظام الفرعي لأتمتة الطاقة الشمسية والمحول في وقت واحد أو وحدة الاستهلاك ؛ وإلا فإنه يعمل بكفاءة كاملة أو أقل. يتم النظر في حالات الفشل والإصلاحات المستقلة إحصائيًا. يتم استخدام ظاهرة الاحتمالات الأولية المدمجة مع المعادلات التفاضلية لفحص موثوقية النظام ، للنظام القابل للإصلاح وغير القابل للإصلاح، ولتحليل دالة التكلفة الخاصة به. يمكن تحسين دقة واتساق النظام من خلال نهج الشبكة العصبية للانتشار الأمامي والخلفي (FFBPNN). يمكن لآلية تعلم النسب المتدرجة أن تقوم بتحديث الأوزان العصبية وبالتالي النتائج تصل إلى الدقة المطلوبة في كل تكرار، وبغض النظر عن مشكلة تلاشي التدرج في الشبكات العصبية الأخرى، مما يزيد من كفاءة النظام في الوقت الفعلي. تم تصميم كود MATLAB لخوارزمية FFBP لتحسين قيم الموثوقية ووظيفة التكلفة من خلال تقليل الخطأ إلى الحد الأدنى حتى 0.0001. يتم النظر في الرسوم التوضيحية العددية مع جداول البيانات والرسوم البيانية الخاصة بهم، لتوضيح النتائج وتحليلها في شكل الموثوقية ووظيفة التكلفة، والتي قد تكون مفيدة لمحللي النظام.Solar energy is one of the immeasurable renewable energy in power generation for a green, clean and healthier environment. The silicon-layer solar panels absorb sun energy and converts it into electricity by off-grid inverter. Electricity is transferred either from this inverter or from transformer, consumed by consumption unit(s) available for residential or economic purposes. The artificial neural network is the foundation of artificial intelligence and solves many complex problems which are difficult by statistical methods or by humans. In view of this, the purpose of this work is to assess the performance of the Solar - Transformer - Consumption (STC) system. The system may be in complete breakdown situation due to failure of both solar power automation subsystem and transformer simultaneously or consumption unit; otherwise it works with fully or lesser efficiency. Statistically independent failures and repairs are considered. Using the elementary probabilities phenomenon incorporated with differential equations is employed to examine the system reliability, for repairable and non-repairable system, and to analyze its cost function. The accuracy and consistency of the system can be improved by feed forward- back propagation neural network (FFBPNN) approach. Its gradient descent learning mechanism can update the neural weights and hence the results up to the desired accuracy in each iteration, and aside the problem of vanishing gradient in other neural networks, that increasing the efficiency of the system in real time. MATLAB code for FFBP algorithm is built to improve the values of reliability and cost function by minimizing the error up to 0.0001 precision. Numerical illustrations are considered with their data tables and graphs, to demonstrate and analyze the results in the form of reliability and cost function, which may be helpful for system analyzers

    Tuftsin-bearing liposomes as drug vehicles in the treatment of experimental aspergillosis

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    AbstractEncapsulation of amphotericin B in tuftsin-bearing liposomes greatly increased its efficacy in treatment of human aspergillosis in mice. Also, the drug efficacy was significantly increased by pretreating the animals with drug-free tuftsin-bearing liposomes. These results demonstrate that macrophage activation can considerably enhance the therapeutic efficacy of antifungal drugs, like amphotericin B

    PREPARATION AND CHARACTERIZATION OF P3HT-PCBM ORGANIC SOLAR CELLS

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    Organic solar cells using P3HT: PCBM as an active layer on ITO coated glass substrates were fabricated and characterized. Different air annealing procedures and cathode materials were tried and the characteristics were compared with that of a standard thin film polycrystalline silicon solar cell. It was found that the sample prepared with post-deposition air annealing at 130 oC improves the open circuit voltage (Voc) considerably. Besides, short circuit current (Isc) and the efficiency (η) were highest for the sample with a non annealed active layer. Series resistance (Rs) for this sample was lowest, but 103 times higher than that of the silicon solar cell, which in turn may have reduced the efficiency value for the organic cell compared to silicon

    Compression And Flexural Properties Of Finger Jointed Mango Wood Sections

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    In this paper, an attempt was made to assess the effectiveness of finger jointing in utilising mango wood sections for various end uses like furniture. The study was based on the estimation of Modulus of elasticity and Modulus of rupture under static bending and Maximum Crushing Stress and Modulus of elasticity under compression parallel to grain of finger jointed sections and comparing them with the values measured for clear wood sections from the same lot. For joining the sections, the Poly Vinyl Acetate and Urea Formaldehyde  adhesives were used. It was found that the Modulus of elasticity of the sections joined by either adhesive showed significantly better values than that of unjointed clear wood sections. The Modulus of rupture values of sections joined with Urea Formaldehyde  were similar to those of unjointed clear wood sections. However, sections jointed with Poly Vinyl Acetate adhesive exhibited lower Modulus of rupture.  Under compression, the parameters of the jointed sections joined with either adhesive were either similar or better than those of the unjointed clear wood sections. The study demonstrates the utility of finger jointing of mango wood sections for furniture parts especially with the Urea Formaldehyde  adhesive

    Solidification behavior of intensively sheared hypoeutectic Al-Si alloy liquid

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    The official published version of this article can be found at the link below.The effect of the processing temperature on the microstructural and mechanical properties of Al-Si (hypoeutectic) alloy solidified from intensively sheared liquid metal has been investigated systematically. Intensive shearing gives a significant refinement in grain size and intermetallic particle size. It also is observed that the morphology of intermetallics, defect bands, and microscopic defects in high-pressure die cast components are affected by intensive shearing the liquid metal. We attempt to discuss the possible mechanism for these effects.Funded by the EPSRC

    Group testing with Random Pools: Phase Transitions and Optimal Strategy

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    The problem of Group Testing is to identify defective items out of a set of objects by means of pool queries of the form "Does the pool contain at least a defective?". The aim is of course to perform detection with the fewest possible queries, a problem which has relevant practical applications in different fields including molecular biology and computer science. Here we study GT in the probabilistic setting focusing on the regime of small defective probability and large number of objects, p0p \to 0 and NN \to \infty. We construct and analyze one-stage algorithms for which we establish the occurrence of a non-detection/detection phase transition resulting in a sharp threshold, Mˉ\bar M, for the number of tests. By optimizing the pool design we construct algorithms whose detection threshold follows the optimal scaling MˉNplogp\bar M\propto Np|\log p|. Then we consider two-stages algorithms and analyze their performance for different choices of the first stage pools. In particular, via a proper random choice of the pools, we construct algorithms which attain the optimal value (previously determined in Ref. [16]) for the mean number of tests required for complete detection. We finally discuss the optimal pool design in the case of finite pp

    A continuous source of translationally cold dipolar molecules

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    The Stark interaction of polar molecules with an inhomogeneous electric field is exploited to select slow molecules from a room-temperature reservoir and guide them into an ultrahigh vacuum chamber. A linear electrostatic quadrupole with a curved section selects molecules with small transverse and longitudinal velocities. The source is tested with formaldehyde (H2CO) and deuterated ammonia (ND3). With H2CO a continuous flux is measured of approximately 10^9/s and a longitudinal temperature of a few K. The data are compared with the result of a Monte Carlo simulation.Comment: 4 pages, 4 figures v2: small changes in the abstract, text and references. Figures 1 & 2 regenerated to prevent errors in the pd

    The Quark-Gluon Plasma in a Finite Volume

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    The statistical mechanics of quarks and gluons are investigated within the context of the canonical ensemble. Recursive techniques are developed which enforce the exact conservation of baryon number, total isospin, electric charge, strangeness, and color. Bose and Fermi-Dirac statistics are also accounted for to all orders. The energy, entropy and particle number densities are shown to be significantly reduced for volumes less than 5 cubic fm.Comment: 8 pages, 3 figure

    Pseudo-unitary symmetry and the Gaussian pseudo-unitary ensemble of random matrices

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    Employing the currently discussed notion of pseudo-Hermiticity, we define a pseudo-unitary group. Further, we develop a random matrix theory which is invariant under such a group and call this ensemble of pseudo-Hermitian random matrices as the pseudo-unitary ensemble. We obtain exact results for the nearest-neighbour level spacing distribution for (2 X 2) PT-symmetric Hamiltonian matrices which has a novel form, s log (1/s) near zero spacing. This shows a level repulsion in marked distinction with an algebraic form in the Wigner surmise. We believe that this paves way for a description of varied phenomena in two-dimensional statistical mechanics, quantum chromodynamics, and so on.Comment: 9 pages, 2 figures, LaTeX, submitted to the Physical Review Letters on August 20, 200
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