Delta/hexagonal phase shifting transformer (PST) represents both magnetically coupled and electrically connected circuits, which makes it unique in design and construction from a standard transformer. Conventionally, ...
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Delta/hexagonal phase shifting transformer (PST) represents both magnetically coupled and electrically connected circuits, which makes it unique in design and construction from a standard transformer. Conventionally, differential protection serves as a main protection element of PST and offers distinguished features such as speed and selectivity. On the contrary, it is prone to various new challenges in addition to well-recognised traditional ones when applied to delta/hexagonal PST. New challenges include non-standard phase shift between two ends, saturation of the series winding, dependence of differential/ restraining currents on tap changer position and turn-turn fault detection. This study exploits the unique design of PST and explores the suitability of applying electromagnetic equations by presenting a new algorithm for the protection of PST. In addition to the internal/external fault detection and discrimination capability, unlike differential protection, the proposed algorithm remains stable during magnetisation inrush current, current transformer saturation and saturation of the series winding. Even though the implementation of the proposed algorithm requires currents, voltages and tracking of the tap-changer position, capabilities of the algorithm make it a distinguished and unique protection solution. Performance of the algorithm is tested and analysed for various fault and non-faulted power system conditions using power systems computer aided design/electromagnetic transient including DC (PSCAD/EMTDC) software.
A method is proposed to retrieve mathematical formula in LaTeX documents. Firstly, we represent the retrieved mathematical formula by binary tree according to its LaTeX description, normalize the structure of the bina...
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A method is proposed to retrieve mathematical formula in LaTeX documents. Firstly, we represent the retrieved mathematical formula by binary tree according to its LaTeX description, normalize the structure of the binary tree, and obtain the structure code and then search the mathematical formula table that is named by the structure code and the formula elements of the first two levels of the binary tree in the mathematical formula database. If the table exists, then we search the normalizing variable name preorder traversing sequence of the binary tree in the table and display the document information that contain the mathematical formula. The experimental results show that the algorithm realizes the retrieval of mathematical formula in LaTeX documents and has higher retrieval precision and faster retrieval speed.
This paper is concerned with the problem of multitarget coverage based on probabilistic detection model. Coverage configuration is an effective method to alleviate the energy-limitation problem of sensors. Firstly, co...
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This paper is concerned with the problem of multitarget coverage based on probabilistic detection model. Coverage configuration is an effective method to alleviate the energy-limitation problem of sensors. Firstly, considering the attenuation of node's sensing ability, the target probabilistic coverage problem is defined and formalized, which is based on Neyman-Peason probabilistic detection model. Secondly, in order to turn off redundant sensors, a simplified judging rule is derived, which makes the probabilistic coverage judgment execute on each node locally. Thirdly, a distributed node schedule scheme is proposed for implementing the distributed algorithm. Simulation results show that this algorithm is robust to the change of network size, and when compared with the physical coverage algorithm, it can effectively minimize the number of active sensors, which guarantees all the targets gamma-covered.
The ideal numerical simulation of 3D magnetotelluric was restricted by the methodology complexity and the time-consuming calculation. Boundary values, the variation of weighted residual equation, and the hexahedral me...
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The ideal numerical simulation of 3D magnetotelluric was restricted by the methodology complexity and the time-consuming calculation. Boundary values, the variation of weighted residual equation, and the hexahedral mesh generation method of finite element are three major causes. A finite element method for 3D magnetotelluric numerical modeling is presented in this paper as a solution for the problem mentioned above. In this algorithm, a hexahedral element coefficient matrix for magnetoelluric finite method is developed, which solves large-scale equations using preconditioned conjugate gradient of the first-type boundary conditions. This algorithm is verified using the homogeneous model, and the positive landform model, as well as the low resistance anomaly model.
Data centers, as resource providers, take advantage of virtualization technology to achieve excellent resource utilization, scalability, and high availability. However, large numbers of computing servers containing vi...
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Data centers, as resource providers, take advantage of virtualization technology to achieve excellent resource utilization, scalability, and high availability. However, large numbers of computing servers containing virtual machines of data centers consume a tremendous amount of energy. Thus, it is necessary to significantly improve resource utilization. Among the many issues associated with energy, scheduling plays a very important role in successful task execution and energy consumption in virtualized environments. This paper seeks to implement an energy-efficient task scheduling algorithm for virtual machines with changeless speed comprised of two main steps: assigning as many tasks as possible to virtual machines with lower energy consumption and keeping the makespan of each virtual machine within a deadline. We propose a novel scheduling algorithm for heterogeneous virtual machines in virtualized environments to effectively reduce energy consumption and finish all tasks before a deadline. The new scheduling strategy is simulated using the CloudSim toolkit package. Experimental results show that our approach outperforms previous scheduling methods by a significant margin in terms of energy consumption.
This paper studies in detail the background and implementation of a teaching-learning based optimization (TLBO) algorithm with differential operator for optimization task of a few mechanical components, which are esse...
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This paper studies in detail the background and implementation of a teaching-learning based optimization (TLBO) algorithm with differential operator for optimization task of a few mechanical components, which are essential for most of the mechanical engineering applications. Like most of the other heuristic techniques, TLBO is also a population-based method and uses a population of solutions to proceed to the global solution. A differential operator is incorporated into the TLBO for effective search of better solutions. To validate the effectiveness of the proposed method, three typical optimization problems are considered in this research: firstly, to optimize the weight in a belt-pulley drive, secondly, to optimize the volume in a closed coil helical spring, and finally to optimize the weight in a hollow shaft. have been demonstrated. Simulation result on the optimization (mechanical components) problems reveals the ability of the proposed methodology to find better optimal solutions compared to other optimization algorithms.
A novel feature selection algorithm is proposed, which is related to the Discriminative Common Vector Approach (DCVA) utilized as a means to reduce the computational complexity of the facial recognition problem. The r...
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A novel feature selection algorithm is proposed, which is related to the Discriminative Common Vector Approach (DCVA) utilized as a means to reduce the computational complexity of the facial recognition problem. The recognition performance of the selected features is tested with DCVA and well known subspace methods over AR and YALE face databases. Moreover, the scheme indicates that important facial parts like eyes, eyebrows, noses, and lips must be kept for recognition purposes while eliminating the pixels in cheek, chin, and forehead areas. This additional knowledge comes out in the form of T-shaped and elliptical face masks used to specify the region of interest (ROI). Hence, besides the excellent dimensionality reduction given by the use of the DCVA technique, there is an intelligent use of the original database that provides superior results even in the presence of an occlusion as it is the case when the facial images have scarves. (C) 2014 Elsevier Ltd. All rights reserved.
Methods and tools for binary code analysis developed in the Institute of System Programming, Russian Academy of Sciences, and their applications in algorithm and data format recovery are considered. The executable cod...
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Methods and tools for binary code analysis developed in the Institute of System Programming, Russian Academy of Sciences, and their applications in algorithm and data format recovery are considered. The executable code of various general-purpose CPU architectures is analyzed. The analysis is performed given no source codes, debugging information, and specific OS version requirements. The approach implies collecting a detailed machine instruction level execution trace;a method for successively increasing presentation level;extraction of algorithm's code followed by structuring of both code and data formats it processes. Important results are obtained, viz. an intermediate representation is developed that allows carrying out most preliminary processing tasks and algorithm code extraction without having to focus on specifics of a given machine;and a method and software tool are developed for automated recovery of network message and file formats. The tools are integrated into the unified analysis platform that supports their combined use. The architecture behind the platform is also described. Examples of its application to real programs are given.
We examine several algorithms for tracking a handheld wand in a 3D virtual reality system: extended Kalman filters (EKFs), interacting multiple models (IMMs), and support vector machines (SVMs). The IMMs consist of se...
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We examine several algorithms for tracking a handheld wand in a 3D virtual reality system: extended Kalman filters (EKFs), interacting multiple models (IMMs), and support vector machines (SVMs). The IMMs consist of several EKF models, each of which is tuned for one particular type of user motion. For determining the types of motion, we compare hand-created rules with an automatic clustering algorithm, with mixed results. The mode-specific EKFs within the IMM are more accurate than one overall EKF. However, the IMM is comparable to a single EKF, because of the overhead of predicting the current component EKF. SVMs with a one-frame lookahead perform the best, cutting the error in half. Aside from those SVMs, different model types were best for the different dimensions of tracking (x, y, z, and rotation).
In this paper, we consider the speech enhancement problem in a moving car through a blind source separation (BSS) scheme involving two spaced microphones. The forward and backward blind source separation structures of...
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In this paper, we consider the speech enhancement problem in a moving car through a blind source separation (BSS) scheme involving two spaced microphones. The forward and backward blind source separation structures often use manual voice activity detector (MVAD) systems to control the adaptation of the separating adaptive filters. In this paper, we propose two new automatic voice activity detector (AVAD) systems that allow adapting the original forward and backward BSS structures automatically. The proposed AVAD systems are based on the use of the forward BSS structure to estimate the optimal values of the separating adaptive filters step-sizes. Moreover, the new proposed algorithms are stable and could be used even in very noisy conditions. Intensive experiments are carried out with these two new proposed algorithms to validate their good performances in speech enhancement and noise reduction applications. The presented experiments are based on the system mismatch, the cepstral distance and the output signal-to-noise ratio criteria evaluations. The obtained results show the good performances of the proposed algorithms in comparison with their original versions, where manual VAD systems are used. (C) 2014 Elsevier Ltd. All rights reserved.
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