Current Issue : April - June Volume : 2017 Issue Number : 2 Articles : 5 Articles
An improved pilot pattern algorithm for facilitating the channel estimation in multiple input\nmultiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems is proposed in\nthis paper. The presented algorithm reconfigures the parameter in the least square (LS) algorithm,\nwhich belongs to the space-time block-coded (STBC) category for channel estimation in pilot-based\nMIMO-OFDM system. Simulation results show that the algorithm has better performance in contrast\nto the classical single symbol scheme. In contrast to the double symbols scheme, the proposed\nalgorithm can achieve nearly the same performance with only half of the complexity of the double\nsymbols scheme....
Near-field acoustical holography (NAH) based on the equivalent source method (ESM) is an efficient method applied for noise\nsource identification. As ...
Tracking and Data Relay Satellite System (TDRSS) is a space-based telemetry, tracking, and command system, which represents a\nresearch field of the international communication.The issue of the dynamic relay satellite scheduling, which focuses on assigning\ntime resource to user tasks, has been an important concern in the TDRSS system. In this paper, the focus of study is on the dynamic\nrelay satellite scheduling, whose detailed process consists of two steps: the initial relay satellite scheduling and the selection of\ndynamic scheduling schemes. To solve the dynamic scheduling problem, a new scheduling algorithm ABC-TOPSIS is proposed,\nwhich combines artificial bee colony (ABC) and technique for order preference by similarity to ideal solution (TOPSIS). The\nartificial bee colony algorithm is performed to solve the initial relay satellite scheduling. In addition, the technique for order\npreference by similarity to ideal solution is adopted for the selection of dynamic scheduling schemes. Plenty of simulation results\nare presented.The simulation results demonstrate that the proposed method provides better performance in solving the dynamic\nrelay satellite scheduling problem in the TDRSS system....
A new fusion sensing (FS) method was proposed by using the improved fractal box\ndimension (IFBD) and a developed maximum wavelet coefficient (DMWC) for fault sensing of\nan online power cable. There are four strategies that were used. Firstly, the traditional fractal box\ndimension was improved to enlarge the feature distances between the different fault classes. Secondly,\nthe IFBD recognition algorithm was proposed by using the improved fractal dimension feature\nextracted from the three-phase currents for the first stage of fault recognition. Thirdly, the DMWC\nrecognition algorithm was developed based on the K-transform and wavelet analysis to establish the\nrelationship between the maximum wavelet coefficient and the fault class. Fourthly, the FS method\nwas formed by combining the IFBD algorithm and the DMWC algorithm in order to recognize the\n10 types of short circuit faults of online power. The designed test system proved that the FS method\nincreased the fault recognition accuracy obviously. In addition, the parameters of the initial angle,\ntransient resistance, and fault distance had no influence on the FS method....
Path planning problem is the core and hot research topic of multiple Automatic\nGuided Vehicles (multi-AGVs) system. Although there are many research results,\nthey do not solve the path planning problem from the perspective of reducing traffic\ncongestion. A collision-free path planning method based on improved A* Algorithm\nfor multi-AGVs logistics sorting system is proposed in this paper. In the method, the\nenvironment of warehouse operation for AGVs is described by using grid method.\nThe estimated cost of A* algorithm is improved by adding the penalty value of the\npaths that AGVs share with each other to alleviate traffic congestion and collision\nresolution rules are made according to different types of collisions. Then the collision-\nfree path planning is done by combing the improved A* algorithm and collision\nresolution rules. The sorting efficiency of the method is compared with that of original\nA* algorithm. Simulation results show that the new collision-free path planning\nmethod can improve the sorting efficiency of multi-AGVs system and relieve traffic\ncongestion....
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