- Fulu Li;Junwei Cao;Chunfeng Wang;Kui Wu;
Trees are arguably one of the most important data structures widely used in information theory and computing science. Different numbers of intermediate nodes in wireless broadcast trees may exert great impacts on the energy consumption of individual nodes, which are typically equipped with a limited power supply in a wireless sensor network; this limitation may eventually determine how long the given wireless sensor network can last. Thus, obtaining a deep understanding of the mathematical nature of wireless broadcast trees is of great importance. In this paper, we give new proof of Cayley's well-known theorem for counting labeled trees. A distinct feature of this proof is that we purely use combinatorial structures instead of constructing a bijection between two kinds of labeled trees, which is in contrast to all existing proofs. Another contribution of this work is the presentation of a new theorem on trees based on the number of intermediate nodes in the tree. To the best of our knowledge,this work is the first to present a tree enumeration theorem based on the number of intermediate nodes in the tree.
2018年03期 v.23 223-232页 [查看摘要][在线阅读][下载 235K] [下载次数：22 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：99 ] - Yangyang Ming;Jie Yang;Junwei Cao;Ziqiang Zhou;Chunxiao Xing;
This paper proposes a distributed averaging iteration algorithm for energy sharing in microgrids of Energy Internet based on common gossip algorithms. This algorithm is completely distributed and only requires communications between neighbors. Through this algorithm, the Energy Internet not only allocates the energy effectively based on the load condition of grids, but also reasonably schedules the energy transmitted between neighboring grids. This study applies theoretical analysis to discuss the condition in which this algorithm can finally reach supply-and-demand balance. Subsequently, the related simulation validates the performance of the algorithm under various conditions.
2018年03期 v.23 233-242页 [查看摘要][在线阅读][下载 816K] [下载次数：39 ] |[网刊下载次数：0 ] |[引用频次：6 ] |[阅读次数：74 ] - Dongsheng Yang;Qianqian Chong;Bo Hu;Min Ma;
Ignoring load characteristics and not considering user feeling with regard to the optimal operation of Energy Internet(EI) results in a large error in optimization. Thus, results are not consistent with the actual operating conditions. To solve these problems, this paper proposes an optimization method based on user Electricity Anxiety(EA) and Chaotic Space Variation Particle Swarm Optimization(CSVPSO). First, the load is divided into critical load, translation load, shiftable load, and temperature load. Then, on the basis of the different load characteristics,the concept of the user EA degree is presented, and the optimization model of the EI is provided. This paper also presents a CSVPSO algorithm to solve the optimization problem because the traditional particle swarm optimization algorithm takes a long time and particles easily fall into the local optimum. In CSVPSO, the particles with lower fitness value are operated by using cross operation, and velocity variation is performed for particles with a speed lower than the setting threshold. The effectiveness of the proposed method is verified by simulation analysis.Simulation results show that the proposed method can be used to optimize the operation of EI on the basis of the full consideration of the load characteristics. Moreover, the optimization algorithm has high accuracy and computational efficiency.
2018年03期 v.23 243-253页 [查看摘要][在线阅读][下载 831K] [下载次数：56 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：40 ] - Syed Furqan Rafique;Jianhua Zhang;Muhammad Hanan;Waseem Aslam;Atiq Ur Rehman;Zmarrak Wali Khan;
This study provides details of the energy management architecture used in the Goldwind microgrid test bed. A complete mathematical model, including all constraints and objectives, for microgrid operational management is first described using a modified prediction interval scheme. Forecasting results are then achieved every 10 min using the modified fuzzy prediction interval model, which is trained by particle swarm optimization.A scenario set is also generated using an unserved power profile and coverage grades of forecasting to compare the feasibility of the proposed method with that of the deterministic approach. The worst case operating points are achieved by the scenario with the maximum transaction cost. In summary, selection of the maximum transaction operating point from all the scenarios provides a cushion against uncertainties in renewable generation and load demand.
2018年03期 v.23 254-265页 [查看摘要][在线阅读][下载 686K] [下载次数：70 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：39 ] - Yang Li;Xinwen Fan;Zhiyuan Cai;Bing Yu;
First, a three-tier coordinated scheduling system consisting of a distribution network dispatch layer, a microgrid centralized control layer, and local control layer in the energy internet is proposed. The multi-time scale optimal scheduling of the microgrid based on Model Predictive Control(MPC) is then studied, and the optimized genetic algorithm and the microgrid multi-time rolling optimization strategy are used to optimize the datahead scheduling phase and the intra-day optimization phase. Next, based on the three-tier coordinated scheduling architecture, the operation loss model of the distribution network is solved using the improved branch current forward-generation method and the genetic algorithm. The optimal scheduling of the distribution network layer is then completed. Finally, the simulation examples are used to compare and verify the validity of the method.
2018年03期 v.23 266-276页 [查看摘要][在线阅读][下载 1540K] [下载次数：59 ] |[网刊下载次数：0 ] |[引用频次：8 ] |[阅读次数：36 ]
- Yi Liu;Danpu Liu;Guangxin Yue;
Existing mobility models have limitations in their ability to simulate the movement of Wireless Body Area Network(WBAN) since body nodes do not exactly follow either classic mobility models or human contact distributions. In this paper, we propose a new mobility model called Body Gauss–Markov Mobility(BGMM) model,which is oriented specially to WBAN. First, we present the random Gauss-Markov mobility model as the most suitable theoretical basis for developing our new model, as its movement pattern can reveal real human body movements. Next, we examine the transfer of human movement states and derive a simplified mathematical Human Mobility Model(HMM). We then construct the BGMM model by combining the RGMM and HMM models. Finally,we simulate the traces of the new mobility model. We use four direct metrics in our proposed mobility model to evaluate its performance. The simulation results show that the proposed BGMM model performs with respect to the direct mobility metrics and can effectively represent a general WBAN-nodes movement pattern.
2018年03期 v.23 277-287页 [查看摘要][在线阅读][下载 2069K] [下载次数：28 ] |[网刊下载次数：0 ] |[引用频次：14 ] |[阅读次数：72 ] - Jizhou Sun;Jianzhong Li;Hong Gao;Hongzhi Wang;
In this era of big data, data are often collected from multiple sources that have different reliabilities, and there is inevitable conflict with respect to the various information obtained when it relates to the the same object.One important task is to identify the most trustworthy value out of all the conflicting claims, and this is known as truth discovery. Existing truth discovery methods simultaneously identify the most trustworthy information and source reliability degrees and are based on the idea that more reliable sources often provide more trustworthy information,and vice versa. However, there are often semantic constrains defined upon relational database, which can be violated by a single data source. To remove violations, an important task is to repair data to satisfy the constrains,and this is known as data cleaning. The two problems above may coexist, but considering them together can provide some benefits, and to the authors knowledge, this has not yet been the focus of any research. In this paper, therefore, a schema-decomposing based method is proposed to simultaneously discover the truth and to clean the data, with the aim of improving accuracy. Experimental results using real world data sets of notebooks and mobile phones, as well as simulated data sets, demonstrate the effectiveness and efficiency of our proposed method.
2018年03期 v.23 288-302页 [查看摘要][在线阅读][下载 533K] [下载次数：32 ] |[网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：74 ] - Gang Li;Haifang Li;Ling Zhang;
It remains a challenging task to segment images that are distorted by noise and intensity inhomogeneity.To overcome these problems, in this paper, we present a novel region-based active contour model based on local intensity information and a kernel metric. By introducing intensity information about the local region, the proposed model can accurately segment images with intensity inhomogeneity. To enhance the model's robustness to noise and outliers, we introduce a kernel metric as its objective functional. To more accurately detect boundaries, we apply convex optimization to this new model, which uses a weighted total-variation norm given by an edge indicator function. Lastly, we use the split Bregman iteration method to obtain the numerical solution. We conducted an extensive series of experiments on both synthetic and real images to evaluate our proposed method, and the results demonstrate significant improvements in terms of efficiency and accuracy, compared with the performance of currently popular methods.
2018年03期 v.23 303-314页 [查看摘要][在线阅读][下载 5066K] [下载次数：23 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：140 ] - Liuqing Chen;Xiaofeng Zhang;Hongbing Ma;
The pansharpening process is for obtaining an enhanced image with both high spatial and high spectral resolutions by fusing a panchromatic(PAN) image and a low spatial resolution multispectral(MS) image. Sparse Principal Component Analysis(SPCA) method has been proposed as a pansharpening method, which utilizes sparse coefficients and over-complete dictionaries to represent the remote sensing data. However, this method still has some drawbacks, such as the existence of the block effect. In this paper, based on SPCA, we propose the Sparse over Shared Coefficients(SSC), in which patches are extracted with a sliding distance of 1 pixel from a PAN image, and the MS image shares the sparse representation coefficients trained from the PAN image independently.The fused high-resolution MS image is reconstructed by K-SVD algorithm and iterations, and residual compensation is applied when the down-sampling constraint is not satisfied. The simulated experiment results demonstrate that the proposed SSC method outperforms SPCA and improves the overall effectiveness.
2018年03期 v.23 315-322页 [查看摘要][在线阅读][下载 344K] [下载次数：24 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：44 ] - Ping Wang;Liuguo Yin;Jianhua Lu;
When implementing helicopter-satellite communications, periodical interruption of the received signal is a challenging problem because the communication antenna is intermittently blocked by the rotating blades of the helicopter. The helicopter-satellite channel model and the Forward Error Control(FEC) coding countermeasure are presented in this paper. On the basis of this model, Check-Hybrid(CH) Low-Density Parity-Check(LDPC)codes are designed to mitigate the periodical blockage over the helicopter-satellite channels. The CH-LDPC code is derived by replacing part of single parity-check code constraints in a Quasi-Cyclic LDPC(QC-LDPC) code by using more powerful linear block code constraints. In particular, a method of optimizing the CH-LDPC code ensemble by searching the best matching component code among a variety of linear block codes using extrinsic information transfer charts is proposed. Simulation results show that, the CH-LDPC coding scheme designed for the helicopter-satellite channels in this paper achieves more than 25% bandwidth efficiency improvement, compared with the FEC scheme that uses QC-LDPC codes.
2018年03期 v.23 323-332页 [查看摘要][在线阅读][下载 579K] [下载次数：79 ] |[网刊下载次数：0 ] |[引用频次：12 ] |[阅读次数：56 ] - Bo Zhang;Yufeng Wang;Li Wei;Qun Jin;Athanasios V.Vasilakos;
Owing to advanced storage and communication capabilities today, smart devices have become the basic interface between individuals and their surrounding environment. In particular, massive devices connect to one other directly in a proximity area, thereby enabling abundant Proximity Services(Pro Se), which can be classified into two categories: public safety communication and social discovery. However, two challenges impede the quick development and deployment of Pro Se applications. From the viewpoint of networking, no multi-hop connectivity functionality component can be directly operated on commercially off-the-shelf devices, and from the programming viewpoint, an easily reusable development framework is lacking for developers with minimal knowledge of the underlying communication technologies and connectivity. Considering these two issues, this paper makes a twofold contribution. First, a multi-hop mesh networking based on Bluetooth Low Energy(BLE) is implemented,in which a proactive routing mechanism with link-quality(i.e., received signal strength indication) assistance is designed. Second, a Pro Se development framework called BLE Mesh is designed and implemented, which can provide significant benefits for application developers, framework maintenance professionals, and end users. Rich application programming interfaces can help developers to build Pro Se apps easily and quickly. Dependency inversion principle and template method pattern allow modules in BLE Mesh to be loosely coupled and easy to maintain and update. Callback mechanism enables modules to work smoothly together and automation processes such as registration, node discovery, and messaging are employed to offer nearly zero-configuration for end users.Finally, based on the designed Pro Se development kit, a public safety communications app called Quote Send App is built to distribute emergency information in close area without Internet access. The process illustrates the easy usability of BLE Mesh to develop Pro Se apps.
2018年03期 v.23 333-346页 [查看摘要][在线阅读][下载 1118K] [下载次数：104 ] |[网刊下载次数：0 ] |[引用频次：8 ] |[阅读次数：84 ] - Jun Xia;Yuqiang Feng;Luning Liu;Dongjun Liu;
To solve the problem of information fusion from multiple sources in innovation alliances, an information fusion model based on the Bayesian network is presented. The multi-source information fusion process of innovation alliances was classified into three layers, namely, the information perception layer, the feature clustering layer,and the decision fusion layer. The agencies in the alliance were defined as sensors through which information is perceived and obtained, and the features were clustered. Finally, various types of information were fused by the innovation alliance based on the fusion algorithm to achieve complete and comprehensive information. The model was applied to a study on economic information prediction, where the accuracy of the fusion results was higher than that from a single source and the errors obtained were also smaller with the MPE less than 3%, which demonstrates the proposed fusion method is more effective and reasonable. This study provides a reasonable basis for decision-making of innovation alliances.
2018年03期 v.23 347-356页 [查看摘要][在线阅读][下载 302K] [下载次数：57 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：87 ] - Ce Sun;Zesong Fei;Dai Jia;Congzhe Cao;Xinyi Wang;
This paper considers the use of polar codes to enable secure transmission over parallel relay channels.By exploiting the properties of polar codes over parallel channels, a polar encoding algorithm is designed based on Channel State Information(CSI) between the legitimate transmitter(Alice) and the legitimate receiver(Bob).Different from existing secure transmission schemes, the proposed scheme does not require CSI between Alice and the eavesdropper(Eve). The proposed scheme is proven to be reliable and shown to be capable of transmitting information securely under Amplify-and-Forward(AF) relay protocol, thereby providing security against passive and active attackers.
2018年03期 v.23 357-365页 [查看摘要][在线阅读][下载 415K] [下载次数：21 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：38 ] - Maosong Sun;Tat-Seng Chua;Yang Liu;Zhiyuan Liu;
<正>The publication of Tsinghua Science and Technology was started in 1996.Since then,it has been an international academic journal sponsored by Tsinghua University and published bimonthly.This journal aims at presenting the state-of-the-art scientific achievements in computer science and other IT fields.From 2012,the journal enters into IEEE Xplore Digital
2018年03期 v.23 366页 [查看摘要][在线阅读][下载 39K] [下载次数：69 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：68 ] - Yutong Lu;Zizhong Chen;Juan Chen;Chao Li;
<正>The publication of Tsinghua Science and Technology was started in 1996.Since then,it has been an international academic journal sponsored by Tsinghua University and published bimonthly.This journal aims at presenting the state-of-the-art scientific achievements in computer science and other IT fields.From 2012,the journal enters into IEEE Xplore Digital
2018年03期 v.23 367-368页 [查看摘要][在线阅读][下载 60K] [下载次数：12 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：58 ]