Advanced Materials Research Vols. 756-759

Abstract: Distributing column storage is one of the techniques to improve the efficiency of big data access under the cloud computing environment. To achieving the aim and reducing network data access frequency, paper established a data localization strategy and designed a multi-thread algorithm. Firstly, segmentalize data in the horizontal direction, and then divide vertically the data table into data column, and ensure that the same level column data localize on the same node in the cluster. Secondly, the essay designed and realized the data localization algorithm under Hadoop distributed cloud computing framework. Finally, experiments show remarkable reduces in the network access with the usage of data localization algorithm, and improvement of the data access efficiency.

Abstract: It is of importance to calculate the parameters of signal timing for TSP (Transit Signal Priority). However, most studies computing the delay are provided based on formula of triangle area. With communication technology developing precisely calculating the delay time of buses can be achieved. The kernel algorithm of TSP still has room for improvement. In this paper, the algorithmic flow of the most of functions is presented based on Enumeration Method.Meanwhile the study uses the VISSIM simulation model to evaluate the impact of a number of alternative priority strategies on both the prioritized buses and general traffic. The priority logic that is considered in the study provides signal timing parameters within a real-time traffic signal control environment. A case study was conducted to validate the model results. Simulation results shows that this method effectively reduces average delay time of the travelers.

Abstract: To the questions of approaching degree between operating point and collapse point, and operating mechanism in the instability, the main method to analyze power system is often the calculation of static voltage stability index. In this paper, a method of microgrid static voltage stability margin based on immune algorithm is proposed. Compared with traditional method, the method not only can search for the global optimal solution effectively, but also deal with discrete variables in the system; meanwhile, complex node of the microgrid is considered entirely .The simulation results confirm that the method is more reasonable and effective for microgrid static voltage stability margin.

Abstract: In this study, in order to improve the search efficiency of causal Bayesian network structure learning, a new tag-based search algorithm is developed. The algorithm uses tags and the topology structure of tags to mark different types of variables, thus narrowing the search space of causal Bayesian network structure learning. With this algorithm, the task of combining causal Bayesian network theory with existing theories or models in certain application establishments when causal analysis is required becomes simpler. The time complexity of the tag-based search algorithm, compared with other search algorithms, has been reduced. Moreover, the experimental results show that the efficiency and accuracy of the tag-based search algorithm are both high.

Abstract: This paper deals with the problem of carrier frequency estimation for MPSK symbols. We present a novel non-data-aided method by introducing a step factor into an earlier estimation algorithm to reduce the computational complexity with little loss of the estimation accuracy. We also make some comparisons with earlier algorithms. From the results of simulations, we make the conclusion that the new method can separate the estimation range and the estimation accuracy, and avoid the weakness of reaching large estimation range at the expense of estimation accuracy.

Abstract: Inverse Discrete Cosine Transform (IDCT) is an important operation for image and videos decompression. How to accelerate the IDCT algorithm has been frequently studied. Recently Intel has proposed Xeon Phi coprocessors based on the many integrated core (MIC) architecture. Xeon Phi is integrated with 61 cores and 512-bit SIMD extension within each core, thus providing very high performance. In this paper, we employ the Knights Corner (a beta version of Xeon Phi) to accelerate the IDCT algorithm. By employing the 512-bit SIMD instruction and data pre-fetching optimization, our implementation achieves (1) averagely 5.82 speedup over the none-SIMD version, (2) averagely 27.3% performance benefit with the data pre-fetching optimization, and (3) averagely 1.53 speedup on one Knights Corner coprocessor over the implementation on one octal-core Intel Xeon E5-2670 CPU.

Abstract: A Parallel Computing is the important method to enhance the speed of multiple data 2-D FFT operation in MPI and is the low-cost, high efficiency project proceeded in a cluster of PCs. This paper discussed the method how to execute the MPI parallel programming in cluster environment, the feasibility of proceeding parallel 2-D FFT in cluster of PCs was discussed and some meaningful conclusions and ways were also achieved., proposed algorithm improved thoughts.

Abstract: Existing algorithms of blind equalization for time-varying channels are slow in convergence, easily interfered, and hard to pinpoint the location of pulsation in the frequency domain. In this paper we present a new blind equalization method that addresses the aforementioned issues. The new solution combines super-exponential algorithm with carrier frequency-offset estimation for time-varying channels. The time-varying channel taps described by the complex exponential basis expansion model (CE-BEM) are expressed as a superposition of time-varying complex exponential bases with time-invariant coefficients. We first employ a super-exponential algorithm to remove the inter-symbol interference caused by time-invariant coefficients. Then we estimate channel pulsation from equalized signals with a carrier frequency-offset estimation algorithm. Compared with existing ones, our solution converges faster with lower inter-symbol interference and easier specification of the pulsation in frequency domain. Simulation results prove the efficiency of the proposed algorithm.

Abstract: NAND flash memory has been successfully employed in storage system due to its advantages such as performance, resistance, and capacity. NAND flash memory based solid state disk (SSD) has started to replace disk in numerous environments. However, the poor endurance offered by these SSDs continues to be their key shortcoming. To improve SSD endurance, we propose a static wear-leveling algorithm with variable threshold (WLVT). In contrast with traditional algorithm with fixed threshold, WLVT adjusts the value of threshold, so that each block can simultaneously reach the erasure times that the manufacturer gives when life of SSD is over. Therefore, available erasure time of each block will be fully utilized when SSD fails. Experimental results show that the endurance of the SSD is significantly improved.

Abstract: Multi-objective arithmetic NSGA-II based on Pareto solution is investigated to deal with integrated optimal design of speedability and manoeuvre performances for submersible. Approximation model of resistance for serial revolving shape is constructed by hydrodynamic numerical calculations. The appraisement criterions of stability and mobility are calculated from linear equation of horizontal movement by estimating hydrodynamic coefficient of submersible. After optimization, the scattered Pareto solution of drag and turning diameter are gained, and from the solutions designer can select the reasonable one based on the actual requirement. The Pareto solution can ensure the minimum drag in this manoeuvre performance or the best manoeuvre performance in this drag value.