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arXiv 2023年

作者： Zhang, Xiao Zhang, Hai Zhou, Hongtu Huang, Chang Zhang, Di Ye, Chen Zhao, Junqiao The Department of Computer Science and Technology Tongji University China The MOE Key Lab of Embedded System and Service Computing Tongji University China

Safety is one of the main challenges in applying reinforcement learning to realistic environmental tasks. To ensure safety during and after training process, existing methods tend to adopt overly conservative policy to avoid unsafe situations. However, overly conservative policy severely hinders the exploration, and makes the algorithms substantially less rewarding. In this paper, we propose a method to construct a boundary that discriminates safe and unsafe states. The boundary we construct is equivalent to distinguishing dead-end states, indicating the maximum extent to which safe exploration is guaranteed, and thus has minimum limitation on exploration. Similar to Recovery Reinforcement Learning, we utilize a decoupled RL framework to learn two policies, (1) a task policy that only considers improving the task performance, and (2) a recovery policy that maximizes safety. The recovery policy and a corresponding safety critic are pretrained on an offline dataset, in which the safety critic evaluates upper bound of safety in each state as awareness of environmental safety for the agent. During online training, a behavior correction mechanism is adopted, ensuring the agent to interact with the environment using safe actions only. Finally, experiments of continuous control tasks demonstrate that our approach has better task performance with less safety violations than state-of-the-art algorithms. Copyright © 2023, The Authors. All rights reserved.

关键词： Reinforcement learning

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Research on Practical Implementation of Binary Arithmetic Coding with Forbidden Symbol for Error Resilience

Research on Practical Implementation of Binary Arithmetic Co...

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2011 International Conference on Frontiers in Computer Education(ICFCE 2011)

作者： Wei Zhang Feng Cen Fanglai Zhu The Key Laboratory of Embedded System and Service Computing Ministry of Education Department of Control Science & Engineering Tongji University

Arithmetic coding is a widely applied compression tool with superior coding efficiency to other entropy coding methodsHowever, it suffers from the error resilience and complexityIn this paper, the integer implementation of binary arithmetic coding with forbidden symbol for error resilience is studiedCoding redundancies for employing different quantization coefficients in probability representation and cost effective backtracking distance in bits for maximum a posteriori(MAP) decoding are studied in depthWe observe that the optimal quantization coefficients are independent of forbidden symbol and the probabilities of source and the cost effective backtracking distance is related to the source entropy and the given forbidden symbol probabilitiesSuch observations are also demonstrated by extensive experiments.

关键词： Arithmetic coding Forbidden symbol Error resilience MAP

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Synchronization of Multi-Weighted and Directed Network Under Pinning Impulsive Control

Synchronization of Multi-Weighted and Directed Network Under...

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Chinese Automation Congress (CAC)

作者： Xiaohan Hu Xiwei Liu Tongji University Shanghai China Key Laboratory of Embedded System and Service Computing Tongji University Shanghai China

ISBN: (纸本)9781665426480

In this paper, multi-weighted and directed complex dynamic networks (MWDCDNs) under the control of hybrid impulses are analyzed. Two cases are considered. In the first case, impulses can be only applied on one fixed node. In the other case, impulses are applied on different nodes according to whether they are synchronized or de-synchronized in MWDCDNs with unbounded time delay. By limiting impulsive interval and Chebyshev distance between the normalized left eigenvectors (NLEVec) of multiple coupling matrices corresponding to the zero eigenvalue, we obtain some criteria for the synchronization of MWDCNs. Some numerical simulation are also given.

关键词： Couplings Sufficient conditions Limiting Automation Delay effects Chebyshev approximation Numerical simulation

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Information Security Evaluation by Information Flow Analysis Based on Stochastic Petri Nets

Information Security Evaluation by Information Flow Analysis...

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2024 IEEE International Conference on systems, Man, and Cybernetics, SMC 2024

作者： Tu, Hanqian Xiang, Dongming Lin, Wang Liu, Guanjun Zhejiang Sci-Tech University Department of Computer Science and Technology Hangzhou310018 China Shanghai Electronic Transactions and Information Service Collaborative Innovation Center Tongji University Key Laboratory of Embedded System and Service Computing Ministry of Education Department of Computer Science Shanghai201804 China

ISBN: (纸本)9781665410205

The Petri-net-based information flow analysis offers an effective approach for detecting information leakage by the concept of non-interference. Although the related studies propose efficient solutions, they lack quantitative evaluation on information leakage. In this paper, we propose a novel method for quantitative evaluation of information security based on stochastic labeled Petri nets (SLPNs) and information flow analysis. Specifically, we introduce four different levels of security metrics, and provide a methodology for evaluating the information security. Furthermore, a case study is presented to show the feasibility of our method. © 2024 IEEE.

关键词： Information leakage

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Effectively compressing Near-Duplicate Videos in a joint way

Effectively compressing Near-Duplicate Videos in a joint way

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IEEE International Conference on Multimedia and Expo (ICME)

作者： Hanli Wang Ming Ma Tao Tian Key Laboratory of Embedded System and Service Computing Tongji University Shanghai P. R. China

With the increasing popularity of social network, more and more people tend to store and transmit information in visual format, such as image and video. However, the cost of this convenience brings about a shock to traditional video servers and expose them under the risk of overloading. Among the huge amount of online videos, there are quite a number of Near-Duplicate Videos (NDVs). Although many works have been proposed to detect NDVs, few researches are investigated to compress these NDVs in a more effective way than independent compression. In this work, we utilize the data redundancy of NDVs and propose a video coding method to jointly compress NDVs. In order to employ the proposed video coding method, a number of pre-processing functions are designed to explore the correlation of visual information among NDVs and to suit the video coding requirements. Experimental results verify that the proposed video coding method is able to effectively compress NDVs and thus save video data storage.

关键词： Videos Video coding Image coding Bit rate Joints Indexes Encoding

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Finite time cluster consensus of fractional-order multi-agent systems with directed topology

Finite time cluster consensus of fractional-order multi-agen...

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第33届中国控制与决策会议

作者： Weijin Liu Xiwei Liu Department of Computer Science and Technology Tongji University Key Laboratory of Embedded System and Service Computing Ministry of Education

In this paper,the finite time cluster consensus(FnTCC) of fractional-order multi-agent systems(FOMAS)with directed topology is *** fractional-order system is converted into an integer-order system by defining a neighborhood-based error variable,and suitable control rules are designed for the obtained first-order multi-agent *** to the exponential finite-time stability theorem,suitable Lyapunov functions are ***,the settling time function is *** simulation results prove the feasibility and validity of our theory.

关键词： Fractional-order Cluster consensus Exponential finite time Multi-agent systems Directed topology

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Incremental Sensor Node Deployment for Low Cost and Highly Available WSNs

Incremental Sensor Node Deployment for Low Cost and Highly A...

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International Conference on Mobile Ad-hoc and Sensor Networks, MSN

作者： Safwan Al-Omari Weisong Shi Jordan University of Science and Technology Jordan Key Laboratory of Embedded System and Service Computing University of Tongji China

We attack the sensor network deployment problem. We define the deployment problem as the problem of deciding how many sensor nodes should be deployed in the sensor field over how many phases during its lifetime. We target the optimal deployment strategy that meets user-defined availability requirement with minimum total cost taking into consideration node failures and changing field trip to sensor node cost ratio. We model WSN availability and total cost as functions of the deployment plan, then, we formalize the deployment problem as a 2D optimization problem. Our modeling enables us to explore cost-benefit tradeoffs, we believe, this is a solid step toward bringing cost as an explicit dimension in the design space of WSN protocols. We compare the performance of the optimized solution (denoted as pro-active) to more ad-hoc solutions: on-demand and at-front. The former strategy schedules future deployments only on demand. The latter strategy deploys all nodes at front with no later field trips. Using extensive simulations, we show that proactive outperforms at-front and on-demand in terms of total cost per availability unit in all application scenarios. For example, using pro-active costs $7 compared to $40 and $280 per total uptime in case of on-demand and at-front, respectively.

关键词： Availability Wireless sensor networks Equations Optimization Mathematical model Business Exponential distribution

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Automatic Web service composition based on Horn clauses and Petri nets

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Expert systems with Applications 2011年第10期38卷 13024-13031页

作者： Tang, Xianfei Jiang, Changjun Zhou, Mengchu Department of Computer Science and Technology Tongji University Shanghai 201804 China Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University Shanghai 201804 China Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark NJ 07102 United States

This paper introduces an automatic Web service composition method based on logical inference of Horn clauses and Petri nets. The Web service composition problem is transformed into the logical inference problem of Horn clauses by exploring the dependency relations among services. An algorithm is presented, to determine whether the composite service exists in time that is linear in the size of the knowledge base. It can also return the rule set necessary for the composition. Petri nets are chosen to model the rule set and its structural analysis techniques are used to obtain the composite service. © 2010 Elsevier Ltd. All rights reserved.

关键词： Automatic reasoning Knowledge base Petri nets service composition Web service

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Process-aware service composition based on Petri net

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Journal of Harbin Institute of Technology (New Series) 2008年第SUPPL.期15卷 162-166页

作者： Sun, Ping Li, Xiangmei Department of Computer Science and Engineering Tongji University Shanghai 201804 China Embedded System and Service Computing Key Laboratory Shanghai 201804 China

One of the most promising advantages of Web service technology is the possibility of creating value-added services by combining existing ones. A major challenge is how to discover and select concrete service according to user requirements. This paper addresses the topic of service discovery composite Web services. The main feature is that we take the process model as well as service profile into account. Firstly, the process models of Web services are translated into Petri nets. Based on this, we propose a service matchmaking algorithm, via comparing the functionality compatibility and process consistency, thus leading to more accurate matchmaking.

关键词： Web services

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Spatial-Temporal Dynamic Graph Diffusion Convolutional Network for Traffic Flow Forecasting

Spatial-Temporal Dynamic Graph Diffusion Convolutional Netwo...

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IEEE International Conference on Big Data

作者： Yang Li Yaying Zhang Key Laboratory of Embedded System and Service Computing Ministry of Education Tongji University Shanghai Artificial Intelligence Laboratory Shanghai China

Traffic forecasting plays a crucial role in intelligent transportation systems and finds application in various domains. Accurate traffic forecasting remains challenging due to the time-varying correlations within the data and the heterogeneous correlations between regions. Although various dynamic spatial-temporal graph models have been proposed to address these challenges in recent years, most of them are burdened by high computation costs and not intuitive to understand. In this paper, we propose a spatial-temporal graph model, Spatial-Temporal Dynamic Graph Diffusion Convolutional Network (SDGDN) that provides an effective and efficient approach to traffic forecasting. From the perspective of traffic flow transition probabilities, SDGDN learns dynamic graph structures to capture the time-varying traffic transition relationships. Besides dynamic graph structures, static node features are employed in diffusion convolution to better capture heterogeneous regional features. Furthermore, we utilize temporal encoding and also generate varying graphs in each stacked layer to enhance the forecasting performance. Experiments results on five real-world datasets demonstrate that SDGDN outperforms most baseline models in terms of both performance and computation efficiency.

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