Testing of algorithms for a stand-alone digital relay for powertransformers

A stand-alone digital relay has been designed and implemented. The relay can be modified easily to accommodate the protection of different types of transformers by changing the software only. Presented in this paper are the real-time experimental results of five selected algorithms implemented using this digital relay. These algorithms are: discrete Fourier transform, Walsh function, rectangular transform, finite impulse response and least-square. Based on the experimental results, the discrete Fourier transform (DFT) algorithm is found to be the best algorithm in terms of accuracy and speed for digital implementation of the differential relay for power transformers     

Efficient adaptive CUSUM control charts based on generalized likelihood ratio test to monitor process dispersion shift

In practice, a shift in the process parameters (location and/or dispersion) is unknown in prior and cannot be diagnosed precisely with the classical cumulative sum (CUSUM) control chart. To overcome this issue, this study proposed two adaptive CUSUM (ACUSUM) control charts. The proposed control charts utilized linear weighted function that is inspired by generalized likelihood ration test (GLRT) to monitor small and certain range of shift in the process dispersion. In more details, the proposed control charts methodologies are based on GLRT, exponentially weight moving average statistic, and score functions. To obtain the run length of the proposed control charts for performance assessment, algorithms are designed in MATLAB based on Monte Carlo simulation technique. Further, average run length (ARL) is used as a performance measure tool to compare the control charts performance for a single shift. For certain range of shift, extra quadratic loss function, relative ARL, and performance comparison index performance measures based on ARL are calculated. Some existing control charts are used for comparison purpose. The proposed control charts show outstanding capability to detect out-of-control signal against these control charts. Moreover, real-life data of inside diameter of cylinder bore in an engine block are used to reveal the practicality and worth of the proposed control charts relative to other control charts.     

A Zeolitic-Imidazole Frameworks-Derived Interconnected Macroporous Carbon Matrix for Efficient Oxygen Electrocatalysis in Rechargeable Zinc–Air Batteries

Nanostructures derived from zeolitic-imidazole frameworks (ZIFs) gain much interest in bifunctional oxygen electrocatalysis. However, they are not satisfied well for long-life rechargeable zinc–air batteries due to the limited single particle morphology. Herein, the preparation of an interconnected macroporous carbon matrix with a well-defined 3D architecture by the pyrolysis of silica templated ZIF-67 assemblies is reported. The matrix catalyst assembled zinc–air battery exhibits a high power density of 221.1 mW cm⁻² as well as excellent stability during 500 discharging/charging cycles, surpassing that of a commercial Pt/C assembled battery. The synergistic effect from the interconnected macroporous structure together with abundant cobalt–nitrogen–carbon active sites justify the excellent electrocatalytic activity and battery performance. Considering the advanced nanostructures and performance, the as-synthesized hybrid would be promising for rechargeable zinc–air batteries and other energy technologies. This work may also provide significant concept in the view of electrocatalysis design for long-life battery.     

Software-Defined Space-Air-Ground Integrated Network Architecture with the Multi-Layer Satellite Backbone Network

Under the background of the rapid development of ground mobile communication, the advantages of high coverage, survivability, and flexibility of satellite communication provide air support to the construction of space information network. According to the requirements of the future space information communication, a software-defined Space-Air-Ground Integrated network architecture was proposed. It consisted of layered structure satellite backbone network, deep space communication network, the stratosphere communication network and the ground network. The SpaceAir-Ground Integrated network was supported by the satellite backbone network. It provided data relay for the missions such as deep space exploration and controlled the deep-space spacecraft when needed. In addition, it safeguarded the anti-destructibility of stratospheric communication and assisted the stratosphere to supplement ground network communication. In this paper, algorithm requirements of the congestion control and routing of satellite backbone protocols for heterogeneous users’ services were proposed. The algorithm requirements of distinguishing different service objects for the deep space communication and stratospheric communication network protocols were described. Considering the realistic demand for the dynamic coverage of the satellite backbone network and node cost, the multi-layer satellite backbone network architecture was constructed. On this basis, the proposed Software-defined Space-Air-Ground Integrated network architecture could be built as a large, scalable and efficient communication network that could be integrated into space, air, and ground.     

Simple Expert System for Evaluation of Nutrient Pollution Potential in Groundwater from Manure Application

An expert system for the evaluation of groundwater pollution potential due to leaching of nutrients from land application of manure is developed in this study. The expert system consists of five modules: surface loading, sorption, vadose zone transport, saturated zone transport, and final module. The expert system evaluates the pollution potential in two steps. In the first step, rating values are evaluated for the selected modules. A set of expert system rules is assigned by the writers to evaluate the rating value of each selected module. In the second step, the pollution potential is evaluated from calculating the weighted average rating of the selected modules. Finally, the expert system is validated against a site assessment done by a group of experts for a concentrated animal feeding operation (CAFO) facility in Oklahoma. The advantages of the expert system are its user-friendliness, requirement of easily available input data, and faster evaluation time. The expert system is recommended to the farmers for improving their management practices and for selecting sites suitable for building new CAFOs. It is also recommended to the regulatory agencies as a screening level tool to identify the most vulnerable sites.     

A semi-analytical solution for a two-dimensional capacitance model in solute transport

A two-dimensional capacitance model is presented for the analysis of solute transport in heterogeneous porous media where the transport processes are affected by mass transfer between the flowing volume in macropores and the stagnant volume in micropores. The semi-analytical solutions for both penetrating and nonpenetrating sources are obtained using double Laplace transforms and numerical inversions. The modeling results reveal the strong influences of dispersive and convective properties of porous media in the transverse direction on the overall transport that cannot be replicated by the current one-dimensional transport models. The solution may provide a useful tool to interpret some transport situations within common field geometries.     

Differential effects of hypoxia with age on the chick embryonic heart. Changes in membrane potential, intracellular K and Na, K efflux and glycogen

The effects of hypoxia on different parameters of cell membrane function were studied in 7 and 19 day chick embryonic hearts. The following changes were observed: 1. Transmembrane potential: A depolarization of the cell membrane and a decrease in the duration and in the overshoot of the action potential. 2. Intracellular ion concentrations: A decrease in (K)i and an increase in (Na)i. Cellular Ca-content remained constant. 3. K efflux: An increase in the rate coefficient, which was larger in stimulated preparations. These changes were more pronounced in 19 day than in 7 day hearts. The effects of hypoxia were increased by simultaneous substrate depletion and counteracted by an excess external glucose. We conclude that: 1. The 19 day hearts are more sensitive to oxygen lack than the 7 day hearts. The difference can be correlated with the observation that the younger hearts are able to consume more glycogen during hypoxia. 2. The changes of the resting membrane potential and the overshoot of the action potential correlate with changes in respectively (K)i and (Na)i. 3. An increase in the background K current may be an important factor in explaining the shortening of the action potential during hypoxia.     

The design and realization of CoViD: a system for collaborative virtual 3D design

Many important decisions in the design process are made during fairly early on, after designers have presented initial concepts. In many domains, these concepts are already realized as 3D digital models. Then, in a meeting, the stakeholders for the project get together and evaluate these potential solutions. Frequently, the participants in this meeting want to interactively modify the proposed 3D designs to explore the design space better. Today’s systems and tools do not support this, as computer systems typically support only a single user and computer-aided design tools require significant training. This paper presents the design of a new system to facilitate a collaborative 3D design process. First, we discuss a set of guidelines which have been introduced by others and that are relevant to collaborative 3D design systems. Then, we introduce the new system, which consists of two main parts. The first part is an easy-to-use conceptual 3D design tool that can be used productively even by naive users. The tool provides novel interaction techniques that support important properties of conceptual design. The user interface is non-obtrusive, easy-to-learn, and supports rapid creation and modification of 3D models. The second part is a novel infrastructure for collaborative work, which offers an interactive table and several large interactive displays in a semi-immersive setup. It is designed to support multiple users working together. This infrastructure also includes novel pointing devices that work both as a stylus and a remote pointing device. The combination of the (modified) design tool with the collaborative infrastructure forms a new platform for collaborative virtual 3D design. Then, we present an evaluation of the system against the guidelines for collaborative 3D design. Finally, we present results of a preliminary user study, which asked naive users to collaborate in a 3D design task on the new system.     

Evidence of irradiation‐induced crosslinking in miscible blends of poly(vinyl chloride)/epoxidized natural rubber in presence of trimethylolpropane triacrylate

Electron‐beam initiated crosslinking of a poly(vinyl chloride)/epoxidized natural rubber blend (PVC/ENR), which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20–200 kGy) and concentrations of TMPTA (1–5 phr). The gelation dose was determined by a method proposed by Charlesby. It was evident from the gelation dose, resilience, hysteresis, glass‐transition temperature (T_g), IR spectroscopy, and scanning electron microscopy studies that the miscible PVC/ENR blend underwent crosslinking by electron‐beam irradiation. The acceleration of crosslinking by the TMPTA was further confirmed in this study. Agreement of the results with a theory relating the T_g with the distance between crosslinks provided further evidence of irradiation‐induced crosslinking. The possible mechanism of crosslinking induced by the irradiation between PVC and ENR is also proposed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1914–1925, 2001