Now, many application services based on location data have brought a lot of convenience to people’s daily life. However, publishing location data may divulge individual sensitive information. Because the location records about location data may be discrete in the database, some existing privacy protection schemes are difficult to protect location data in data mining. In this paper, we propose a travel trajectory data record privacy protection scheme (TMDP) based on differential privacy mechanism, which employs the structure of a trajectory graph model on location database and frequent subgraph mining based on weighted graph. Time series is introduced into the location data; the weighted trajectory model is designed to obtain the travel trajectory graph database. We upgrade the mining of location data to the mining of frequent trajectory graphs, which can discover the relationship of location data from the database and protect location data mined. In particular, to improve the identification efficiency of frequent trajectory graphs, we design a weighted trajectory graph support calculation algorithm based on canonical code and subgraph structure. Moreover, to improve the data utility under the premise of protecting user privacy, we propose double processes of adding noises to the subgraph mining process by the Laplace mechanism and selecting final data by the exponential mechanism. Through formal privacy analysis, we prove that our TMDP framework satisfies ε ‐differential privacy. Compared with the other schemes, the experiments show that the data availability of the proposed scheme is higher and the privacy protection of the scheme is effective.
Convolution computing plays an important role in scientific computing. However, traditional Message Passing Interface (MPI) model has the disadvantages such as massive message passing and load-unbalancing. According to these problems, this paper propose a new parallel convolution based on MPI model, which is able to effectively balance the load as well as bring great reduction on message passing. By analyzing the speedup ratio and efficiency, conclusions can be drawn that the new MPI parallel programming, which obtains obvious promotions on parallel efficiency and large-scale sequence's speed, can better exert the advantages of parallel computing and distributional memories between nodes. And it is shown by the experimental results that the proposed method is a feasible and effective parallel strategy.
Identification and addressing the entity which accesses the internet through the wireless network with various short distance transmission protocols is a key issue. To solve the problem, by combining with the existing identification and addressing technology of the internet and the IOT, this paper proposes a method based on distributed ID. This method can be divided into two stages. It first designs the structure of distributed ID. Using the distributed address allocation algorithm, it implements the automatic allocation of the distributed ID as well as the distributed ID resolution among the global IOT. After that, an addressing scheme is designed to meet demands of the IOT addressing. It first defines the structure of addressing and then implements the routing addressing algorithm which combines the cluster-tree algorithm with the ad hoc on-demand distance vector routing algorithm. This scheme could improve the routing efficiency as well as achieve lower cost, lower energy consumption and higher reliability of the addressing. By the simulation on NS-2 platform, the experimental results highlight the feasibility and effectiveness of the proposed method from three aspects: the correctness of identification allocation, the effectiveness of addressing scheme, and the stability of data transmission.
This study investigates the effects of using an online Automated Essay Assessing (AEA) system on EFL graduate students' writing. Eighty four EFL graduate students divided into the treatment group and the control group participated in this study. The treatment group was asked to use an AEA system to assist their essay writing. Both groups were pretested before the treatment. After the sixteen-week treatment period, the writing posttest was given to both groups to measure their progress in their writing. The results indicate that, although both groups have no significant difference in the pretest, the difference between their mean scores on the posttest is statistically significant. The mean score of the treatment group is higher than that of the control group, and students' use frequency of the AEA system is closely related to their writing improvement. Therefore, it is concluded that, students' using the AEA system contributes significantly to their writing improvement. Thus a linear regression is modeled to predict the weight of the AEA system use frequency to proficiency improvement in writing. Finally, students' perceptions based on their learning journals and interviews show the changes in the process of writing.
A novel blind source extraction algorithm based on cumulative autocorrelation is proposed to solve the problem of satellite-based automatic identification system signal separation. The cumulative autocorrelation of any mixed real signal is proved to be between the minimal and maximal values of the cumulative autocorrelation of its component source signals. In the proposed algorithm, the cumulative autocorrelation of the signal is used as the objective function and an artificial bee colony algorithm is used for optimization. A separated signal component is removed using the deflation method, and the entire source signal can be successfully removed by repeating the separation process. Simulation results show that the algorithm can effectively realize the blind separation of mixed satellite-based AIS signals
Coral mud is widely distributed in the South China Sea. Studying deformation laws of coral mud is important to the infrastructure development in the South China Sea. In this article, a one-dimensional oedometer test of coral mud under near-natural conditions is performed. The exponential fitting model, Burgers model and ODGM model are used to analyse the time-strain relationship of coral mud under different vertical pressures. The self-fitting accuracy and prediction accuracy of the three models under different vertical pressures are compared. Then, the number of data points used in the model was reduced, and the associated change in accuracy and model stability of the three models were analysed. The study found that the ODGM model has high self-fitting, high prediction accuracy, and a high model stability when the number of data points is reduced, which describe the long-term nonlinear deformation of coral mud more accurately.
PDF HTML阅读 XML下载 导出引用 引用提醒 一种分片式多核处理器的用户级模拟器 DOI: 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: Supported by the National Natural Science Foundation of China under Grant No.60673146 (国家自然科学基金); the National Natural Foundation of China for Distinguished Young Scholars under Grant No.60325205 (国家杰出青年基金); the National High-Tech Research and Development Plan of China under Grant No.2006AA010201 (国家高技术研究发展计划(863)); the National Basic Research Program of China under Grant No.2005CB321600 (国家重点基础研究发展计划(973)); the Beijing Natural Science Foundation of China under Grant No.4072024 (北京市自然科学基金); the Knowledge Innovation Program of the Institute of Computing Technology, the Chinese Academy of Sciences under Grant No.20066012 (中国科学院计算技术研究所知识创新课题) A Use-Level Simulator for Tiled Chip Multiprocessor Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:随着片上晶体管资源的增多和互连线延迟的加大,分片式多核微处理器已成为多核处理器设计的新方向.为了对这种新型处理器进行体系结构的深入研究和设计空间的探索,设计并实现了针对分片式多核处理器的用户级多核性能模拟器.该多核模拟器在龙芯2号单处理器核的基础上,完整地模拟了基于目录的Cache一致性协议和存储转发式片上互联网络的结构模型,详细地刻画了由于系统乱序处理各种请求应答和请求之间的冲突而造成的时序特性,可以通过运行各种串行或并行的工作负载对多核处理器的各种重要性能指标加以评估,为多核处理器的结构设计提供了快速、灵活、高效的研究平台. Abstract:As the transistor resources and delay of interconnect wires increase, the tiled multi-core processor has been a new direction for multi-core processor. In order to thoroughly study new type processor and explore the design space of it, this paper designs and implements a user-level performance simulator for the tiled CMP architecture. The simulator adopts the directory-based Cache Coherence Protocol and the architecture of store-and-forward Network- on-Chip with Godson-2 CPU as the processing core model, and depicts out-of-order transacted requests and responses and conflictions of requests and their timing characteristics in detail. The simulator can be used to evaluate all kinds of important performance features of the tiled CMP (chip multiprocessor) architecture by running all kinds of sequential or parallel workloads, and thus provides a fast, flexible and efficient platform for architecture design of multi-core processor. 参考文献 相似文献 引证文献
Packet dropping policies in delay tolerant network are mostly ignored during the years. However, it is shown that the traditional packet dropping policies can not work well in the DTN environment. In this paper we analyze the performance of the traditional packet dropping policies and proposed a new policy which drops packet according to its weight. Packet's weight is calculated using historical information. Experiment results show that our new policy performs much better than traditional ones thus is good to be used in the delay tolerant network.
In this paper, the privacy and security issues associated with transactive energy systems over insecure communications are addressed. In particular, it is ensured that, during market-based interactions: (1) each agent's bidding information remains private; and (2) any extraneous data injection attack can be easily detected. A unified cryptography-based approach that can simultaneously achieve both objectives is developed, where privacy preservation is realized by the Paillier encryption scheme, and attack detection is achieved by the Paillier digital signature scheme. Simulation results verify the effectiveness of the proposed cyber-resilient design for transactive energy systems.
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