Planning and Protection Implications of Reduced Fault-Withstand Time of Power Transformers

The recent revisions (1980-1983) to the standards for power transformers in both the U.S.A. and Canada call for corresponding revisions in many related planning and protection practices. Particularly, it is found that the reduction to 2 seconds for maximum through faults on transformers and the necessity to include a value for system impedance in the specification of the larger transformers will have significant effects on previous practices for planning, protection, operations, loading and specification. This paper discusses a number of these effects, with an emphasis from a protection point of view.     

Distributed polar-coded OFDM based on Plotkin’s construction for half duplex wireless communication

A Plotkin-based polar-coded orthogonal frequency division multiplexing (P-PC-OFDM) scheme is proposed and its bit error rate (BER) performance over additive white gaussian noise (AWGN), frequency selective Rayleigh, Rician and Nakagami-m fading channels has been evaluated. The considered Plotkin’s construction possesses a parallel split in its structure, which motivated us to extend the proposed P-PC-OFDM scheme in a coded cooperative scenario. As the relay’s effective collaboration has always been pivotal in the design of cooperative communication therefore, an efficient selection criterion for choosing the information bits has been inculcated at the relay node. To assess the BER performance of the proposed cooperative scheme, we have also upgraded conventional polar-coded cooperative scheme in the context of OFDM as an appropriate bench marker. The Monte Carlo simulated results revealed that the proposed Plotkin-based polar-coded cooperative OFDM scheme convincingly outperforms the conventional polar-coded cooperative OFDM scheme by 0.5 ~ 0.6 dBs over AWGN channel. This prominent gain in BER performance is made possible due to the bit-selection criteria and the joint successive cancellation decoding adopted at the relay and the destination nodes, respectively. Furthermore, the proposed coded cooperative schemes outperform their corresponding non-cooperative schemes by a gain of 1 dB under an identical condition.     

A high‐speed RSD‐based flexible ECC processor for arbitrary curves over general prime field

This workpresents a novel high‐speed redundant‐signed‐digit (RSD)‐based elliptic curve cryptographic (ECC) processor for arbitrary curves over a general prime field. The proposed ECC processor works for any value of the prime number and curve parameters. It is based on a new high speed Montgomery multiplier architecture which uses different parallel computation techniques at both circuit level and architectural level. At the circuit level, RSD and carry save techniques are adopted while pre‐computation logic is incorporated at the architectural level. As a result of these optimization strategies, the proposed Montgomery multiplier offers a significant reduction in computation time over the state‐of‐the‐art. At the system level, to further enhance the overall performance of the proposed ECC processor, Montgomery ladder algorithm with (X,Y)‐only common Z coordinate (co‐Z) arithmetic is adopted. The proposed ECC processor is synthesized and implemented on different Xilinx Virtex (V) FPGA families for field sizes of 256 to 521 bits. On V‐6 platform, it computes a single 256 to 521 bits scalar point multiplication operation in 0.65 to 2.6 ms which is up to 9 times speed‐up over the state‐of‐the‐art.     

The structural,morphological and thermal properties of grafted pH-sensitive interpenetrating highly porous polymeric composites of sodium alginate/acrylic acid copolymers for controlled delivery of diclofenac potassium

In present investigation new formulations of Sodium Alginate/Acrylic acid hydrogels with high porous structure were synthesized by free radical polymerization technique for the controlled drug delivery of analgesic agent to colon. Many structural parameters like molecular weight between crosslinks (M_c), crosslink density (M_r), volume interaction parameter (v_2,s), Flory Huggins water interaction parameter and diffusion coefficient (Q) were calculated. Water uptake studies was conducted in different USP phosphate buffer solutions. All samples showed higher swelling ratio with increasing pH values because of ionization of carboxylic groups at higher pH values. Porosity and gel fraction of all the samples were calculated. New selected samples were loaded with the model drug (diclofenac potassium).The amount of drug loaded and released was determined and it was found that all the samples showed higher release of drug at higher pH values. Release of diclofenac potassium was found to be dependent on the ratio of sodium alginate/acrylic acid, EGDMA and pH of the medium. Experimental data was fitted to various model equations and corresponding parameters were calculated to study the release mechanism. The Structural, Morphological and Thermal Properties of interpenetrating hydrogels were studied by FTIR, XRD, DSC, and SEM.     

A Comparative Study of Various Hybrid Wavelet Feedforward Neural Network Models for Runoff Forecasting

Considering network topologies and structures of the artificial neural network (ANN) used in the field of hydrology, one can categorize them into two different generic types: feedforward and feedback (recurrent) networks. Different types of feedforward and recurrent ANNs are available, but multilayer perceptron type of feedforward ANN is most commonly used in hydrology for the development of wavelet coupled neural network (WNN) models. This study is conducted to compare performance of the various wavelet based feedforward artificial neural network (ANN) models. The feedforward ANN types used in the study include the multilayer perceptron neural network (MLPNN), generalized feedforward neural network (GFFNN), radial basis function neural network (RBFNN), modular neural network (MNN) and neuro-fuzzy neural network (NFNN) models. The rainfall-runoff data of four catchments located in different hydro-climatic regions of the world is used in the study. The discrete wavelet transformation (DWT) is used in the present study to decompose input rainfall data using db8 wavelet function. A total of 220 models are developed in this study to evaluate the performance of various feedforward neural network models. Performance of the developed WNN models is compared with their counterpart simple models developed without applying wavelet transformation (WT). The results of the study are further compared with - multiple linear regression (MLR) model which suggest that the WNN models outperformed their counterpart simple models. The hybrid wavelet models developed using MLPNN, the GFFNN and the MNN models performed best among the six selected data driven models explored in the study. Moreover, performance of the three best models is found to be similar and thus the hybrid wavelet GFFNN and the MNN models can be considered as an alternative to the most commonly used hybrid WNN models developed using MLPNN. The study further reveals that the wavelet coupled models outperformed their counterpart simple models only with the parsimonious input vector.     

用于家庭及工业和公共设施的两性表面活性剂

论述了两性表面活性剂的温和性、去污性以及高润湿、低发泡和在碱性或酸性条件下稳定的特性。其良好的亲水性和耦合能力使其广泛应用于家庭、工业和公共设施的清洁产品中。这些表面活性剂在个人护理用品产业中应用广泛，同时也给家用产品制造商提供了丰厚的利润，这种应用态势正呈现出增长的趋势。     

Green synthesis of biodegradable terpolymer modified starch nanocomposite with carbon nanoparticles for food packaging application

As to control the increased rate of environmental pollution there is an urgent need to develop improved biodegradable materials regarding the old polymeric packaging materials. It has been done by the incorporation of carbon nanomaterials to the biodegradable starch terpolymers of acrylic acid, methyl methacrylate (MMA), acrylonitrile (AN), 2-Ethylhexyl acrylate (2-EHA), and Ethyl acrylate (EA). The starch-terpolymers were prepared through the free radical polymerization technique using AA, MMA, AN, 2-EHA, EA as monomers. Two different starch-terpolymers were further mixed with carbon nanoparticles (NPs) to form a biodegradable nanocomposite. The biodegradable starch-grafted terpolymers-carbon nanocomposites (STPC NCs) were characterized through scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimeter, and UV–Visible spectrophotometry. Further, resistivity, electrical conductivity, and biodegradability tests were performed to check its properties for packing materials. The biodegradation of SGCP-composites recorded using the soil burial method was up to 78%. Starch-terpolymers were prepared via free-radical polymerization The biodegradation capability of starch-grafted terpolymers was found to be 78% The decrease in water vapor permeability and solubility proves their utilization as food packaging material     

Holistic simulation of wind turbines with fully aero-elastic and electrical model

Requirements for the design of wind turbines advance facing the challenges of a high content of renewable energy sources in the public grid. A high percentage of renewable energy weaken the grid and grid faults become more likely, which add additional loads on the wind turbine. Load calculations with aero-elastic models are standard for the design of wind turbines. Components of the electric system are usually roughly modeled in aero-elastic models and therefore the effect of detailed electrical models on the load calculations is unclear. A holistic wind turbine model is obtained, by combining an aero-elastic model and detailed electrical model into one co-simulation. The holistic model, representing a DFIG turbine is compared to a standard aero-elastic model for load calculations. It is shown that a detailed modelling of the electrical components e.g., generator, converter, and grid, have an influence on the results of load calculations. An analysis of low-voltage-ride-trough events during turbulent wind shows massive increase of loads on the drive train and effects the tower loads. Furthermore, the presented holistic model could be used to investigate different control approaches on the wind turbine dynamics and loads. This approach is applicable to the modelling of a holistic wind park to investigate interaction on the electrical level and simultaneously evaluate the loads on the wind turbine.

     

Stochastic Numerical Analysis for Impact of Heavy Alcohol Consumption on Transmission Dynamics of Gonorrhoea Epidemic

This paper aims to perform a comparison of deterministic and stochastic models. The stochastic modelling is a more realistic way to study the dynamics of gonorrhoea infection as compared to its corresponding deterministic model. Also, the deterministic solution is itself mean of the stochastic solution of the model. For numerical analysis, first, we developed some explicit stochastic methods, but unfortunately, they do not remain consistent in certain situations. Then we proposed an implicitly driven explicit method for stochastic heavy alcohol epidemic model. The proposed method is independent of the choice of parameters and behaves well in all scenarios. So, some theorems and simulations are presented in support of the article.