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Search Results: 1 - 10 of 127510 matches for " Jianzhong Li "
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Efficient Pr-Skyline Query Processing and Optimization in Wireless Sensor Networks  [PDF]
Jianzhong Li, Shuguang Xiong
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.211101
Abstract: As one of the commonly used queries in modern databases, skyline query has received extensive attention from database research community. The uncertainty of the data in wireless sensor networks makes the corresponding skyline uncertain and not unique. This paper investigates the Pr-Skyline problem, i.e., how to compute the skyline with the highest existence probability in a computational and energy-efficient way. We formulate the problem and prove that it is NP-Complete and cannot be approximated in a given expression. However, the proposed algorithm SKY-SEARCH with pruning techniques can guarantee the computational efficiency given relatively large input size, while the filter-based distributed optimization strategy significantly reduces the transmission cost and the required storage space of the sensor nodes. Extensive experiments verify the efficiency and scalability of SKY-SEARCH and the distributed optimizing strategy.
Compressing Information of Target Tracking in Wireless Sensor Networks  [PDF]
Jianzhong Li, Qianqian Ren
Wireless Sensor Network (WSN) , 2011, DOI: 10.4236/wsn.2011.32008
Abstract: Target tracking is a well studied topic in wireless sensor networks. It is a procedure that nodes in the network collaborate in detecting targets and transmitting their information to the base-station continuously, which leads to data implosion and redundancy. To reduce traffic load of the network, a data compressing based target tracking protocol is proposed in this work. It first incorporates a clustering based data gather method to group sensor nodes into clusters. Then a novel threshold technique with bounded error is proposed to exploit the spatial correlation of sensed data and compress the data in the same cluster. Finally, the compact data presentations are transmitted to the base-station for targets localization. We evaluate our approach with a comprehensive set of simulations. It can be concluded that the proposed method yields excellent performance in energy savings and tracking quality.
K-Nearest Neighbor Based Missing Data Estimation Algorithm in Wireless Sensor Networks  [PDF]
Liqiang Pan, Jianzhong Li
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.22016
Abstract: In wireless sensor networks, the missing of sensor data is inevitable due to the inherent characteristic of wireless sensor networks, and it causes many difficulties in various applications. To solve the problem, the missing data should be estimated as accurately as possible. In this paper, a k-nearest neighbor based missing data estimation algorithm is proposed based on the temporal and spatial correlation of sensor data. It adopts the linear regression model to describe the spatial correlation of sensor data among different sensor nodes, and utilizes the data information of multiple neighbor nodes to estimate the missing data jointly rather than independently, so that a stable and reliable estimation performance can be achieved. Experimental results on two real-world datasets show that the proposed algorithm can estimate the missing data accurately.
Optimal Choice of Cotton Subsidy Mode in China—Empirical Study Based on Principal Component Regression  [PDF]
Jianzhong Shi, Yuhong Li
Modern Economy (ME) , 2013, DOI: 10.4236/me.2013.47050

Adopt principal component regression for researching the optimal subsidy mode of cotton production in China. The result indicates that, from the perspective of economic stimulatory effect, the optimal cotton subsidy in China is farm chemical subsidy rather than seed subsidy. The reason is that there are frequent pest disasters in cotton producing areas in China. So farm chemical subsidy is the most important factor ensuring cotton production. Meanwhile, cotton varieties must be optimized and improved to increase the ability to resist pests and diseases, and the forecasting for pests and diseases in cotton production areas must be enhanced, early warning mechanism and monitoring must be built, and in addition, it is strongly recommended that if financial resources allow, subsidies like seed subsidy, fertilizer subsidy, machinery subsidy and irrigation subsidy could also put into effect in China.

Range Query Processing in Multidisk Systems
计算机科学技术学报 , 1992,
Abstract: In order to reduce the disk access time,a database can be stored on several simultaneously accessible disks.In this paper,we are concerned with the dynamic d-attribute database allocation problem for range queries,An allocation method,called coordinate moule allocation method,is proposed to allocate data in a d-attribute database among disks so that the maximum disk accessing concurrency can be achieved for range queries.Our analysis and experiments show that the method achieves the optimum or near-optimum parallelism for range queries.The paper offers the conditions under which the method is optimal .The worst case bounds of the performance of the method are also given.In addition,the parallel algorithm of processing range queries in described at the end of the paper.The method has been used in the statistic and scientific database management system whic is being designed by us.
Approximate Continuous Aggregation via Time Window Based Compression and Sampling in WSNs  [PDF]
Lei Yu, Jianzhong Li, Siyao Cheng
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.29081
Abstract: In many applications continuous aggregation of sensed data is usually required. The existing aggregation schemes usually compute every aggregation result in a continuous aggregation either by a complete aggregation procedure or by partial data update at each epoch. To further reduce the energy cost, we propose a sampling-based approach with time window based linear regression for approximate continuous aggregation. We analyze the approximation error of the aggregation results and discuss the determinations of parameters in our approach. Simulation results verify the effectiveness of our approach.
Investigation on Combustion Characteristics in Channel with Obstacles for Internal Combustion Wave Rotor  [PDF]
Jianzhong Li, Li Yuan, Erlei Gong, Wei Li, Kaichen Zhang
Open Journal of Fluid Dynamics (OJFD) , 2017, DOI: 10.4236/ojfd.2017.72013
Abstract: This paper establishes a simplified test system for internal combustion wave rotor with a single channel and designs different intensifying combustion obstacles and arrangements. Moreover, this paper analyzes the intensifying effect of obstacles on combustion process of the internal combustion wave rotor from the stable operation range, pressure gain and flame progression process perspective. The results show that the range of inlet velocity under stable operation of the internal combustion wave rotor narrows after the addition of obstacles, and the corresponding velocity values substantially reduce while the flame propagation speed can be improved by 2 - 4 times. At the rotation rate of 1500 rpm, the pressure gain increases significantly during the combustion process. These results provide technical supports for further research and application of the internal combustion wave rotor.
Non-blocking Disk-tape Join Algorithm for Data on Tertiary Storage Systems
Baoliang Liu,Jianzhong Li
Information Technology Journal , 2006,
Abstract: The Non-blocking Disk-tape join (NDT) presented in this study was the first disk-tape join algorithm designed with the goal of producing join results as early as possible. It has three phases: the hashing phase, the merging phase and the probing phase. Join results can be produced in each phase. Tuples of disk resident relation and tape resident relation was read simultaneously into memory and be joined in the hashing phase. The merging phase joins those tuples that flushed onto disk during the hashing phase. After the first two phases, disk resident relation has been partitioned and then joined with remaining tape resident relation in the probing phase. Experimental results showed that NDT can produce join results much earlier than the-state-of-art CDT-GH and the performance of NDT was about the same with that of CDT-GH.
Study on Numerical Simulation of Oil-Water Phase Non-Darcy Flow in Low-Permeability Reservoirs  [PDF]
Rongqiang Li, Jianzhong Wang
Open Access Library Journal (OALib Journal) , 2016, DOI: 10.4236/oalib.1102313
Abstract: Based on the basic laws of non-Darcy seepage in low permeability media as well as dynamic permeability, a dynamic function of permeability is derived. On this basis, factoring in the effect of the non-linearity and the starting pressure gradient, a piecewise numerical simulation model was established for low permeability reservoirs and through discretization, a numerical model was obtained. According to the results of the simulation test, this model and method reflect well the seepage in low permeability reservoirs, expressing more objectively the influence of the starting pressure gradient and the non-linearity.

Li Jianzhong,

软件学报 , 1992,
Abstract: A prototype system for statistical/scientific data management based on bit vector storage structure, called VSSDB, is presented in this paper. The physical organization, query processing method and the time complexity model of the query processing are discussed. A new compression method for bit vectors is proposed also.
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