Determination of Capacity Benefit Margin in Multiarea Power Systems Using Particle Swarm Optimization

Available transfer capability (ATC) is a key index of the remaining capability of a transmission system for future transactions. To calculate the ATC between two areas in an interconnected power system, capacity benefit margin (CBM) is one of the indexes that need to be assessed. CBM ensures security of system operation when the system faces generation deficiency in some areas. In this paper, three new methods are introduced which reflect different objectives for CBM assessment. This provides more flexibility of choices for market participants. In the proposed methods, CBM determination is formulated as an optimization problem and particle swarm optimization (PSO) method is used to solve the problem. The numerical results for modified IEEE reliability test system are presented to demonstrate the effectiveness of the proposed approaches.     

Compressive estimation for signal integration in rendering

In rendering applications, we are often faced with the problem of computing the integral of an unknown function. Typical approaches used to estimate these integrals are often based on Monte Carlo methods that slowly converge to the correct answer after many point samples have been taken. In this work, we study this problem under the framework of compressed sensing and reach the conclusion that if the signal is sparse in a transform domain, we can evaluate the integral accurately using a small set of point samples without requiring the lengthy iterations of Monte Carlo approaches. We demonstrate the usefulness of our framework by proposing novel algorithms to address two problems in computer graphics: image antialiasing and motion blur. We show that we can use our framework to generate good results with fewer samples than is possible with traditional approaches.     

Effect of different precooking methods on chemical composition and lipid damage of silver carp (Hypophthalmichthys molitrix) muscle

The influence of three precooking methods (steaming, oven‐baking and microwave‐cooking) on the chemical composition and lipid quality of silver carp fillets was evaluated. The changes in protein, fat and moisture were found to be significant for all the treatments (P ≤ 0.05). The iron content in the samples subjected to steam‐cooking increased; however, the other precooking methods did not change the mineral contents (P ≥ 0.05). The free fatty acid content of the fillets did not change by the different precooking methods, while thiobarbituric acid (TBA) values increased for oven‐ and microwave‐cooked fillets and remained constant in the steam‐cooked samples. Conjugated diene and browning colour formation levels significantly increased in the oven‐baked fillets. Oven‐baking and microwave‐cooking marginally affected the fatty acid composition of the silver carp. On comparing the raw and precooked fillets, steam‐cooking was found to be the best precooking method on retaining nutritional constituents.     

Cellulose nanofibers from the skin of beavertail cactus,Opuntia basilaris,as reinforcements for polyvinyl alcohol

In this study, the skin of the beavertail cactus, Opuntia Basilaris, was used for the isolation of cellulose nanofibers using a chemo‐mechanical technique. It was shown that the skins had a relatively high cellulose content, whereas their lignin content was low. Fourier transform infrared spectroscopy and X‐ray diffraction proved that the isolation of cellulose nanofibers from the amorphous components of the skins was performed successfully. The cactus skins were also shown to have a high content of calcium oxalate crystals. Morphological observations proved that the isolated cellulose fibers had diameters in the range of 10–50 nm. It was shown that the addition of nanofibers increased the modulus and strength of the polyvinyl alcohol matrix significantly, whereas the elongation at break decreased. Thermogravimetric analysis proved that: (i) isolated nanofibers had higher thermal stabilities than the cactus skins, and (ii) inclusion of nanofibers increased the stability of polyvinyl alcohol noticeably. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42499.     

On hyperbolic laws of capacitor discharge through self‐timed digital loads

A new model to predict the dynamic behavior of a self‐timed autonomous digital system powered by a capacitor is derived. The model demonstrates the hyperbolic shape of the discharging process on the capacitor. It allows a symbolic analysis of the discharging process for complex digital loads comprised of series (stack) and parallel configurations of digital circuits. For example, for a stack configuration, important non‐trivial relationships between the hyperbolic discharging rates have been derived based on the knowledge of the velocity saturation index (alpha) of the semiconductor devices used in the digital part. For a realistic (modern complementary metal oxide semiconductor (CMOS) devices) value of alpha = 1.5, the discharging process for a stack of two identical circuits proceeds nearly three times slower than that of any of the stand‐alone circuits. This shows a potential way of extending the lifetime of the energy sources by means of stacking self‐timed circuits. Although the analysis is based on configurations consisting of ring oscillators in CMOS technology, the analysis method can be extended to other types of self‐timed systems and other semiconductor technologies in which the instantaneous switching activity of the digital load is determined by the instantaneous voltage levels provided by the capacitive power transfer mechanism. The analytical derivations have been validated by simulations and experiments carried out with real hardware. © 2014 The Authors. International Journal of Circuit Theory and Applications published by John Wiley & Sons, Ltd.     

Numerical solution of stokes flow in a circular cavity using mesh-free local RBF-DQ

This work reports the results of a numerical investigation of Stokes flow problem in a circular cavity as an irregular geometry using mesh-free local radial basis function-based differential quadrature (RBF-DQ) method. This method is the combination of differential quadrature approximation of derivatives and function approximation of Radial Basis Function. As a result, the method can be used to directly approximate the derivatives of dependent variables on a scattered set of knots. In this study knots were distributed irregularly in the solution domain using the Halton sequences. The method is applied on a two-dimensional geometry. The obtained results from the numerical simulations are compared with those gained by previous works. Outcomes prove that the current technique is in very good agreement with previous investigations and this fact that RBF-DQ method is an accurate and flexible method in solution of partial differential equations (PDEs).     

Shape memory response of porous NiTi shape memory alloys fabricated by selective laser melting

Porous NiTi scaffolds display unique bone-like properties including low stiffness and superelastic behavior which makes them promising for biomedical applications. The present article focuses on the techniques to enhance superelasticity of porous NiTi structures. Selective Laser Melting (SLM) method was employed to fabricate the dense and porous (32–58%) NiTi parts. The fabricated samples were subsequently heat-treated (solution annealing?+?aging at 350?°C for 15?min) and their thermo-mechanical properties were determined as functions of temperature and stress. Additionally, the mechanical behaviors of the samples were simulated and compared to the experimental results. It is shown that SLM NiTi with up to 58% porosity can display shape memory effect with full recovery under 100?MPa nominal stress. Dense SLM NiTi could show almost perfect superelasticity with strain recovery of 5.65 after 6% deformation at body temperatures. The strain recoveries were 3.5, 3.6, and 2.7% for samples with porosity levels of 32%, 45%, and 58%, respectively. Furthermore, it was shown that Young’s modulus (i.e., stiffness) of NiTi parts can be tuned by adjusting the porosity levels to match the properties of the bones.

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Solvent-free synthesis of Cu-Cu2O nanocomposites via green thermal decomposition route using novel precursor and investigation of its photocatalytic activity

In the present study, Cu-Cu₂O binary nanocomposites were successfully synthesized through a one-pot, cost-effective and green thermal decomposition route using PMP-Cu(II), extracted from pomegranate marc peels (PMP) by Cu(II), as a novel starting reagent for the first time. The morphology, crystalline structure, and composition of as-prepared Cu-Cu₂O nanocomposites were extensively characterized by SEM, XRD, EDS and HRTEM. Effect of reaction parameters such as time, temperature and precursor type on product composition and morphology was evaluated. Moreover, methylene blue (MB) was used as a model of organic dye pollutant and photodegradation experiments were conducted by UV-vis spectrophotometry. The as-synthesized Cu-Cu₂O binary nanocomposites demonstrated their potential as an excellent photocatalyst for degradation of MB under visible-light irradiation and Cu-Cu₂O photocatalyst with higher content of Cu₂O (prepared in air) exhibits the highest photocatalytic efficiency (～99% degradation of MB in <150 min).     

Performance evaluation of EWMA and CUSUM control charts to detect anomalies in social networks using average and standard deviation of degree measures

Detection of communication outbreak among members of a network or a subgroup of a network has been a topic of interest in the literature of social network analysis. One approach to monitoring changes in a social network is to monitor graph measures related to the network representation in each period and detecting anomalies by applying a control chart. In this paper, we compare the performance of average degree and standard deviation of degree measures of a network for detecting outbreaks on a weighted undirected network using exponentially weighted moving average and cumulative sum control charts. Evaluation results indicate that average degree measure is better in detecting small changes than standard deviation of degree measure. Whereas for greater changes and outbreaks consisting of more members of the network, the opposite is true. In addition, exponentially weighted moving average control charts perform better than cumulative sum in detecting smaller changes and outbreaks consisting of less members of the network.     

Microscale 3D Printing of Nanotwinned Copper

Nanotwinned (nt)‐metals exhibit superior mechanical and electrical properties compared to their coarse‐grained and nanograined counterparts. nt‐metals in film and bulk forms are obtained using physical and chemical processes including pulsed electrodeposition (PED), plastic deformation, recrystallization, phase transformation, and sputter deposition. However, currently, there is no process for 3D printing (additive manufacturing) of nt‐metals. Microscale 3D printing of nt‐Cu is demonstrated with high density of coherent twin boundaries using a new room temperature process based on localized PED (L‐PED). The 3D printed nt‐Cu is fully dense, with low to none impurities, and low microstructural defects, and without obvious interface between printed layers, which overall result in good mechanical and electrical properties, without any postprocessing steps. The L‐PED process enables direct 3D printing of layer‐by‐layer and complex 3D microscale nt‐Cu structures, which may find applications for fabrication of metamaterials, sensors, plasmonics, and micro/nanoelectromechanical systems.