- Dan Tao;Zhaowen Lin;Cheng Lu;
With respect to security, the use of various terminals in the mobile Internet environment is problematic.Traditional terminal testing methods cannot simulate actual testing environments; thus, the test results do not accurately reflect the security of terminals. To address this problem, we designed and developed a cloud platform based automated testing system for the mobile Internet. In this system, virtualization and automation technology are utilized to integrate mobile terminals into the cloud platform as a resource, to achieve a novel cloud service called Testing as a Service(Taa S). The system consists of three functional modules: web front-end module, testing environment module, and automated testing module. We adopted the permeable automated testing tool Metasploit to perform security testing. In our test experiments, we selected 100 apps with diverse vulnerability levels, ranging from secure to vulnerable, to perform a series of functional tests. The experimental results show that this system can correctly test both the number of vulnerable apps and their corresponding vulnerability levels. As such, the designed system can flexibly configure various testing environments for different testing cases or projects, and thereby perform security testing automatically.
2015年06期 v.20 537-544页 [查看摘要][在线阅读][下载 696K] [下载次数:148 ] |[网刊下载次数:0 ] |[引用频次:8 ] |[阅读次数:0 ] - Goutham Kamath;Lei Shi;Edmond Chow;Wenzhan Song;Junjie Yang;
Modern seismic sensors are capable of recording high precision vibration data continuously for several months. Seismic raw data consists of information regarding earthquake's origin time, location, wave velocity, etc.Currently, these high volume data are gathered manually from each station for analysis. This process restricts us from obtaining high-resolution images in real-time. A new in-network distributed method is required that can obtain a high-resolution seismic tomography in real time. In this paper, we present a distributed multigrid solution to reconstruct seismic image over large dense networks. The algorithm performs in-network computation on large seismic samples and avoids expensive data collection and centralized computation. Our evaluation using synthetic data shows that the proposed method accelerates the convergence and reduces the number of messages exchanged. The distributed scheme balances the computation load and is also tolerant to severe packet loss.
2015年06期 v.20 545-559页 [查看摘要][在线阅读][下载 1187K] [下载次数:27 ] |[网刊下载次数:0 ] |[引用频次:1 ] |[阅读次数:0 ] - Chengjian Liu;Kai Ouyang;Xiaowen Chu;Hai Liu;Yiu-Wing Leung;
Large-scale key-value stores are widely used in many Web-based systems to store huge amount of data as(key, value) pairs. In order to reduce the latency of accessing such(key, value) pairs, an in-memory cache system is usually deployed between the front-end Web system and the back-end database system. In practice, a cache system may consist of a number of server nodes, and fault tolerance is a critical feature to maintain the latency Service-Level Agreements(SLAs). In this paper, we present the design, implementation, analysis, and evaluation of R-Memcached, a reliable in-memory key-value cache system that is built on top of the popular Memcached software. R-Memcached exploits coding techniques to achieve reliability, and can tolerate up to two node failures.Our experimental results show that R-Memcached can maintain very good latency and throughput performance even during the period of node failures.
2015年06期 v.20 560-573页 [查看摘要][在线阅读][下载 1583K] [下载次数:60 ] |[网刊下载次数:0 ] |[引用频次:9 ] |[阅读次数:0 ]
- Dong Wang;Bo Bai;Wei Chen;
In a coordinated multipoint transmission system with centralized architecture for saving power consumption, total power metric is minimized while completely using the backhaul capacity and maintaining the minimum target data rate. The problem is formulated as a mixed integer optimization problem, which is difficult to solve. To overcome this problem, a joint user selection and rate adaptation scheme is developed based on the water-filling rate adaptation with the given user set and the power saving criterion with the allocated rates.Numerical results demonstrate that compared with the norm-based and semi-orthogonal user selection algorithms,the proposed algorithm can significantly reduce the total power consumption. The proposed algorithm can also achieve near-optimal performance compared with the performance achieved by the exhaustive search-based method. In addition, the computational complexity of the proposed algorithm is reduced by heuristic iteration and search scope shrinking.
2015年06期 v.20 574-582页 [查看摘要][在线阅读][下载 509K] [下载次数:10 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:0 ] - Talluri Lakshmi Siva Rama Krishna;Thirumalaisamy Ragunathan;Sudheer Kumar Battula;
File-sharing semantics is used by the file systems for sharing data among concurrent client processes in a consistent manner. Session semantics is a widely used file-sharing semantics in Distributed File Systems(DFSs). The main disadvantage of session semantics is that writes to an open file are visible to the concurrent client processes only during their next session. Recently, "linearizability semantics" was introduced in Blob Seer DFS, in which a Read Client Process(RCP) can read only a previous version of a binary large object(blob), while update operations are carried out on that blob in a concurrent manner. In this paper, we propose a new type of file-sharing semantics, namely "speculative semantics", which permits writes to an open file to be visible to other concurrent processes provided that data consistency is not affected. In addition, we propose a new read algorithm for DFSs based on speculative semantics and a new performance measurement metric called Currency. The experimental results obtained using Blob Seer DFS indicate that the proposed read algorithm performs better than the existing read algorithm of Blob Seer DFS.
2015年06期 v.20 583-593页 [查看摘要][在线阅读][下载 559K] [下载次数:60 ] |[网刊下载次数:0 ] |[引用频次:4 ] |[阅读次数:0 ] - Yichen Zheng;Xiangyu Xi;Yifan Zhuang;Yi Zhang;
To simulate the passenger behavior in subway system, a Dynamic Parameters Cellular Automaton(DPCA) model is put forward in this paper. Pedestrian traffic flows during waiting, getting on or off, and traveling can be simulated. The typical scenario in Beijing Subway Line 13 is modeled to analyze the passenger behavior in subway system. By comparing simulation results with statistical ones, the correctness and practicality of the DPCA model are verified. At last, the additional results made by DPCA model can make contribution to passenger comfort analysis and pedestrian facility planning and guidance.
2015年06期 v.20 594-601页 [查看摘要][在线阅读][下载 589K] [下载次数:44 ] |[网刊下载次数:0 ] |[引用频次:6 ] |[阅读次数:0 ] - Yanping Zhang;Zihui Jing;Yiwen Zhang;
In the era of big data, data intensive applications have posed new challenges to the field of service composition. How to select the optimal composited service from thousands of functionally equivalent services but different Quality of Service(Qo S) attributes has become a hot research in service computing. As a consequence,in this paper, we propose a novel algorithm MR-IDPSO(Map Reduce based on Improved Discrete Particle Swarm Optimization), which makes use of the improved discrete Particle Swarm Optimization(PSO) with the Map Reduce to solve large-scale dynamic service composition. Experiments show that our algorithm outperforms the parallel genetic algorithm in terms of solution quality and is efficient for large-scale dynamic service composition. In addition,the experimental results also demonstrate that the performance of MR-IDPSO becomes more better with increasing number of candidate services.
2015年06期 v.20 602-612页 [查看摘要][在线阅读][下载 446K] [下载次数:43 ] |[网刊下载次数:0 ] |[引用频次:7 ] |[阅读次数:0 ] - Jing Qin;Xinyue Liu;Hongfei Lin;
An audio information retrieval model based on Manifold Ranking(MR) is proposed, and ranking results are improved using a Relevance Feedback(RF) algorithm. Timbre components are employed as the model's main feature. To compute timbre similarity, extracting the spectrum features for each frame is necessary; the large set of frames is clustered using a Gaussian Mixture Model(GMM) and expectation maximization. The typical spectra frame from GMM is drawn as data points, and MR assigns each data point a relative ranking score, which is treated as a distance instead of as traditional similarity metrics based on pair-wise distance. Furthermore, the MR algorithm can be easily generalized by adding positive and negative examples from the RF algorithm and improves the final result. Experimental results show that the proposed approach effectively improves the ranking capabilities of existing distance functions.
2015年06期 v.20 613-619页 [查看摘要][在线阅读][下载 434K] [下载次数:21 ] |[网刊下载次数:0 ] |[引用频次:3 ] |[阅读次数:0 ] - Shu Zhao;Wang Ke;Jie Chen;Feng Liu;Menghan Huang;Yanping Zhang;Jie Tang;
Community structure is one of the most important features in real networks and reveals the internal organization of the vertices. Uncovering accurate community structure is effective for understanding and exploiting networks. Tolerance Granulation based Community Detection Algorithm(TGCDA) is proposed in this paper, which uses tolerance relation(namely tolerance granulation) to granulate a network hierarchically. Firstly, TGCDA relies on the tolerance relation among vertices to form an initial granule set. Then granules in this set which satisfied granulation coefficient are hierarchically merged by tolerance granulation operation. The process is finished till the granule set includes one granule. Finally, select a granule set with maximum granulation criterion to handle overlapping vertices among some granules. The overlapping vertices are merged into corresponding granules based on their degrees of affiliation to realize the community partition of complex networks. The final granules are regarded as communities so that the granulation for a network is actually the community partition of the network.Experiments on several datasets show our algorithm is effective and it can identify the community structure more accurately. On real world networks, TGCDA achieves Normalized Mutual Information(NMI) accuracy 17.55% higher than NFA averagely and on synthetic random networks, the NMI accuracy is also improved. For some networks which have a clear community structure, TGCDA is more effective and can detect more accurate community structure than other algorithms.
2015年06期 v.20 620-626页 [查看摘要][在线阅读][下载 381K] [下载次数:35 ] |[网刊下载次数:0 ] |[引用频次:3 ] |[阅读次数:0 ] - Jiawei Xu;Keda Wang;Chao Wang;Feng Hu;Zhenhua Zhang;Shiyi Xu;Jie Wu;
Wireless sensor networks are a favorite target of Byzantine malicious attackers because of their limited energy, low calculation capability, and dynamic topology, and other important characteristics. The Byzantine Generals Problem is one of the classical problems in the area of fault tolerance, and has wide application, especially in distributed databases and systems. There is a lot of research in agreement and replication techniques that tolerate Byzantine faults. However, most of this work is not suited to large-scale wireless sensor networks, due to its high computational complexity. By introducing Fast ECDSA(Elliptic Curve Digital Signature Algorithm), which can resist timing and energy attacks, and reduce the proportion of verifying signature algorithm to generating signature algorithm to 1.2 times, we propose a new Byzantine fault-tolerant routing algorithm for large-scale wireless sensor networks with double-level hierarchical architecture. In different levels, the algorithm runs different BFT protocols.Theory and simulation results have proved that this algorithm has high security and the number of communication rounds between clusters is reduced by 1/3, which balances the network load. At the same time, the application of Fast ECDSA improves the security level of the network without burdening it.
2015年06期 v.20 627-633页 [查看摘要][在线阅读][下载 508K] [下载次数:42 ] |[网刊下载次数:0 ] |[引用频次:6 ] |[阅读次数:0 ] - Mingming Jiang;Dandan Song;Lejian Liao;Feida Zhu;
Intuitively, not only do ratings include abundant information for learning user preferences, but also reviews accompanied by ratings. However, most existing recommender systems take rating scores for granted and discard the wealth of information in accompanying reviews. In this paper, in order to exploit user profiles' information embedded in both ratings and reviews exhaustively, we propose a Bayesian model that links a traditional Collaborative Filtering(CF) technique with a topic model seamlessly. By employing a topic model with the review text and aligning user review topics with "user attitudes"(i.e., abstract rating patterns) over the same distribution, our method achieves greater accuracy than the traditional approach on the rating prediction task. Moreover, with review text information involved, latent user rating attitudes are interpretable and "cold-start" problem can be alleviated.This property qualifies our method for serving as a "recommender" task with very sparse datasets. Furthermore,unlike most related works, we treat each review as a document, not all reviews of each user or item together as one document, to fully exploit the reviews' information. Experimental results on 25 real-world datasets demonstrate the superiority of our model over state-of-the-art methods.
2015年06期 v.20 634-643页 [查看摘要][在线阅读][下载 262K] [下载次数:49 ] |[网刊下载次数:0 ] |[引用频次:6 ] |[阅读次数:0 ] - Daming Zhang;Yongpan Liu;Shuangchen Li;Tongda Wu;Huazhong Yang;
As performance requirements for bus-based embedded System-on-Chips(So Cs) increase, more and more on-chip application-specific hardware accelerators(e.g., filters, FFTs, JPEG encoders, GSMs, and AES encoders) are being integrated into their designs. These accelerators require system-level tradeoffs among performance, area, and scalability. Accelerator parallelization and Point-to-Point(P2P) interconnect insertion are two effective system-level adjustments. The former helps to boost the computing performance at the cost of area,while the latter provides higher bandwidth at the cost of routability. What's more, they interact with each other. This paper proposes a design flow to optimize accelerator parallelization and P2 P interconnect insertion simultaneously.To explore the huge optimization space, we develop an effective algorithm, whose goal is to reduce total So C latency under the constraints of So C area and total P2 P wire length. Experimental results show that the performance difference between our proposed algorithm and the optimal results is only 2.33% on average, while the running time of the algorithm is less than 17 s.
2015年06期 v.20 644-660页 [查看摘要][在线阅读][下载 1021K] [下载次数:30 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:0 ] - Hongli Zhang;Cong Wang;Wenhui Fan;
A Projection Pursuit Dynamic Cluster(PPDC) model optimized by Memetic Algorithm(MA) was proposed to solve the practical problems of nonlinearity and high dimensions of sample data, which appear in the context of evaluation or prediction in complex systems. Projection pursuit theory was used to determine the optimal projection direction; then dynamic clusters and minimal total distance within clusters(min TDc) were used to build a PPDC model. 17 agronomic traits of 19 tomato varieties were evaluated by a PPDC model. The projection direction was optimized by Simulated Annealing(SA) algorithm, Particle Swarm Optimization(PSO), and MA. A PPDC model,based on an MA, avoids the problem of parameter calibration in Projection Pursuit Cluster(PPC) models. Its final results can be output directly, making the cluster results objective and definite. The calculation results show that a PPDC model based on an MA can solve the practical difficulties of nonlinearity and high dimensionality of sample data.
2015年06期 v.20 661-671页 [查看摘要][在线阅读][下载 615K] [下载次数:61 ] |[网刊下载次数:0 ] |[引用频次:6 ] |[阅读次数:0 ] <正>The publication of Tsinghua Science and Technology was started in 1996.It is an international academic journal sponsored by Tsinghua University and published bimonthly.This journal aims at presenting the state-of-art scientific achievements in computer science and other IT fields.From 2012,the journal enters into IEEE Xplore Digital Library with the
2015年06期 v.20 672页 [查看摘要][在线阅读][下载 52K] [下载次数:20 ] |[网刊下载次数:0 ] |[引用频次:0 ] |[阅读次数:0 ]