检索结果-南通市图书馆

CUDA-Zero:a framework for porting shared memory GPU applications to multi-GPUs

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(information sciences) 2012年第3期55卷 663-676页

作者： CHEN DeHao , CHEN WenGuang & ZHENG WeiMin department of computer science and technology, tsinghua university, beijing 100084, china 1. department of computer science and technology Tsinghua University Beijing 100084 China

As the prevalence of general purpose computations on GPU, shared memory programming models were proposed to ease the pain of GPU programming. However, with the demanding needs of more intensive workloads, it’s desirable to port GPU programs to more scalable distributed memory environment, such as multi-GPUs. To achieve this, programs need to be re-written with mixed programming models (e.g. CUDA and message passing). Programmers not only need to work carefully on workload distribution, but also on scheduling mechanisms to ensure the efficiency of the execution. In this paper, we studied the possibilities of automating the process of parallelization to multi-GPUs. Starting from a GPU program written in shared memory model, our framework analyzes the access patterns of arrays in kernel functions to derive the data partition schemes. To acquire the access pattern, we proposed a 3-tiers approach: static analysis, profile based analysis and user annotation. Experiments show that most access patterns can be derived correctly by the first two tiers, which means that zero efforts are needed to port an existing application to distributed memory environment. We use our framework to parallelize several applications, and show that for certain kinds of applications, CUDA-Zero can achieve efficient parallelization in multi-GPU environment.

关键词： CUDA parallelization data access pattern multi-GPU

RRM:An incentive reputation model for promoting good behaviors in distributed systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science in china(Series F) 2008年第11期51卷 1871-1882页

作者： ZHANG Hong1,2,DUAN HaiXin1,3 & LIU Wu1,3 1 tsinghua National Laboratory for information science and technology,tsinghua university,beijing 100084,china 2 department of computer science and technology,tsinghua university,beijing 100084,china 3 Network Research Center,tsinghua university,beijing 100084,china 1. tsinghua National Laboratory for information science and technology Tsinghua University Beijing 100084 China 2. department of computer science and technology Tsinghua University Beijing 100084 China 3. Network Research Center Tsinghua University Beijing 100084 China

Reputation systems represent soft security mechanisms that complement traditional information security mechanisms. They are now widely used in online e-commerce markets and communities in order to stimulate good behaviors as well as to restrain adverse behaviors. This paper analyzes the limitations of the conversational reputation models and proposes an incentive reputation model called the resilient reputation model （RRM） for the distributed reputation systems. The objective of this reputation model is not only to encourage the users to provide good services and, therefore, to maximize the probability of good transaction outcomes, but also to punish those adverse users who are trying to manipulate the application systems. The simulation results indicate that the proposed reputation model （RRM） could effectively resist against the common adverse behaviors, while protecting the profits of sincere users from being blemished by those adversaries.

关键词： reputation model distributed system trust soft security

维普期刊数据库

Optimizing write operation on replica in data grid

在线全文

学校读者我要写书评

暂无评论

science china(information sciences) 2011年第1期54卷 1-11页

作者： XU PengZhi,WU YongWei,HUANG XiaoMeng, YANG GuangWen & ZHENG WeiMin department of computer science and technology,tsinghua university,beijing 100084,china 1. department of computer science and technology Tsinghua University Beijing 100084 China

Replication technique can improve access performance and data availability of data grid systems. So far,most related work on data replication in data grid systems focuses on read-only *** write operations have been widely used in practice,its optimization problem has not been suciently *** this paper,we show that write requests from users can be processed by a nearest site,regardless of the location of latest written *** policy of write nearby instead of write to the latest replica can improve the performance of write operations,while inconsistency is caused between multiple ***,we propose two metadata management algorithms to make sure that users can retrieve up-to-date datasets at any *** extend OptorSim to support the implementation and evaluation of our *** results of simulation show that our scheme achieves performance gains up to 3.3 compared with WriteMaster scheme.

关键词： replication data grid simulation access latency

Multi secret image color visual cryptography schemes for general access structures

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2006年第4期16卷 431-436页

作者： YI Feng, WANG Daoshun , LUO Ping, HUANG Liansheng and DAI Yiqi department of computer science and technology, tsinghua university, beijing 100084, china [a]department of computer science and technology Tsinghua University Beijing China

In the proposed visual cryptography schemes for general access structures, the single secret image black-and-white visual cryptography schemes with meaningful shares have been constructed, in which the shares are innocent looking images. The meaningful shares have not been realized in single secret image color schemes; neither have the multi secret images color schemes. In this paper, the multi secret images color visual cryptography schemes for general access structures with meaningful shares are constructed by the method of matrix concatenation, the pixel expansion is obtained, and the validity of the scheme is proven. In our scheme, the different combination of meaningful color shares can be used to recover distinct color secret images. The multi secret images black-and-white visual cryptography scheme is a special case of our color scheme.

关键词： visual cryptography secret sharing scheme general access structure.

Fuzzy dynamic characteristic modeling and adaptive control of nonlinear systems and its application to hypersonic vehicles

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(information sciences) 2011年第3期54卷 460-468页

作者： LI HongBo , SUN ZengQi, MIN HaiBo & DENG JianQiu department of computer science and technology, tsinghua university, beijing 100084, china 1. department of computer science and technology Tsinghua University Beijing 100084 China

In this paper, a fuzzy dynamic characteristic modeling and adaptive control method is proposed for a class of nonlinear systems. By employing fuzzy dynamic characteristic model, the controlled plant is described as a slowly time-varying fuzzy system, wherein the parameters are estimated online by using recursive Least-Squares algorithm. Under this framework, a fuzzy adaptive controller is constructed, and the stability condition of the closed-loop system is also derived. The main advantage of the proposed method lies in no requirement for the prior knowledge of system model and less parameters to tune, which allows engineers to operate it in a simple, straightforward manner. The proposed method is applied to the control of hypersonic vehicle, and simulation results are given to demonstrate the effectiveness of the obtained results.

关键词： fuzzy control dynamic characteristic model adaptive control hypersonic vehicle

A stochastic policy search model for matching behavior

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(information sciences) 2011年第7期54卷 1430-1443页

作者： CHENG ZhenBo 1,2,ZHANG Yu 1 & DENG ZhiDong 1 1 State Key Laboratory on Intelligent technology and Systems,tsinghua National Laboratory for information science and technology,department of computer science,tsinghua university,beijing 100084,china 2 department of computer science and technology,Zhejiang university of technology,Hangzhou 310014,china 1. State Key Laboratory on Intelligent technology and Systems Tsinghua National Laboratory for Information Science and Technology Department of Computer Science Tsinghua University Beijing 100084 China2. Department of Computer Science and Technology Zhejiang University of Technology Hangzhou 310014 China

The matching law is one of the basic empirical laws in decision theory,and it states that a subject’s preference to optional targets depends on which choices are *** this paper,we study the possible mechanisms that explain why subjects’ decisions often obey this *** the basis of reinforcement learning theory,we put forward a decision-making model in which the policy is updated by a policy parameter,and the model might be implemented in the brain through the prefrontal cortex and the basal ganglia neural *** on this model,an algorithm that satisfies the matching law is derived under some simple *** analysis and simulation results show that the decision behavior achieved by the algorithm obeys the matching *** addition,the matching behaviors in two classical experiments are reproduced using the *** results provide a reasonable strategy for the matching law and a useful computational tool for rewarded decision-making tasks.

关键词： policy model matching law reinforcement learning decision-making model

A formal method to real-time protocol interoperability testing

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science in china(Series F) 2008年第11期51卷 1723-1744页

作者： WANG ZhiLiang1,3,YIN Xia2,3 & JING ChuanMing2,3 1 Network Research Center,tsinghua university,beijing 100084,china 2 department of computer science and technology,tsinghua university,beijing 100084,china 3 tsinghua National Laboratory for information science and technology(TNList) ,beijing 100084,china 1. Network Research Center Tsinghua University Beijing 100084 China 3. tsinghua National Laboratory for information science and technology (TNList) Beijing 100084 China 2. department of computer science and technology Tsinghua University Beijing 100084 China

Interoperability testing is an important technique to ensure the quality of implementations of network communication protocol. In the next generation Internet protocol, real-time applications should be supported effectively. However, time constraints were not considered in the related studies of protocol interoperability testing, so existing interoperability testing methods are difficult to be applied in real-time protocol interoperability testing. In this paper, a formal method to real-time protocol interoperability testing is proposed. Firstly, a formal model CMpTIOA （communicating multi-port timed input output automata） is defined to specify the system under test （SUT） in real-time protocol interoperability testing; based on this model, timed interoperability relation is then defined. In order to check this relation, a test generation method is presented to generate a parameterized test behavior tree from SUT model; a mechanism of executability pre-determination is also integrated in the test generation method to alleviate state space explosion problem to some extent. The proposed theory and method are then applied in interoperability testing of IPv6 neighbor discovery protocol to show the feasibility of this method.

关键词： protocol testing interoperability testing real-time testing test generation timed input output automata(TIOA)

维普期刊数据库

A　Nonprecedence－based　Query　Schedule　Algorithm　on　Heterogeneous　Multiprocessor　System

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 1995年第3期6卷 63-69页

作者： He Jun bang Dingxing & Zheng Weimin(department of computer science & technology,tsinghua university, beijing, 100084, china) department of computer science & technology Tsinghua University Beijing 100084 China

There has been a number of algorithms designed to handle intra-query or inter-query scheduling in multiprocessor-based parallel database system. They all have the assumption that the processorsare identical. But in some cases, such as shared nothing environment, this assumption would not be fullyvalid. In this paper we devise and evaluate a scheduling algorithm ELLIST to handle nonprecedence-basedheterogeneous malleable scheduling problem. It uses LLIST-NM as subroutine that handles nonmalleablescheduling without precedence and assuming the processors are identical. Even though the problem we considered is NP-hard in the strong sense, the schedule generated by our algorithm is seen experimentally toachieve results that are close to optimum when there are enough tasks to be scheduled.

关键词： Heterogeneous malleable scheduling Makespan Affinity

维普期刊数据库

Fusion tracking in color and infrared images using joint sparse representation

在线全文

学校读者我要写书评

暂无评论

science china(information sciences) 2012年第3期55卷 590-599页

作者： LIU HuaPing1,2,3 & SUN FuChun1,2,3 1department of computer science and technology, tsinghua university, beijing 100084, china 2State Key Laboratory of Intelligent technology and Systems, beijing 100084, china 3tsinghua National Laboratory for information science and technology, beijing 100084, china 1. department of computer science and technology Tsinghua University Beijing 100084 China2. State Key Laboratory of Intelligent Technology and Systems Beijing 100084 China3. Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China

Currently sparse signal reconstruction gains considerable interest and is applied in many fields. In this paper, a similarity induced by joint sparse representation is designed to construct the likelihood function of particle filter tracker so that the color visual spectrum and thermal spectrum images can be fused for object tracking. The proposed fusion scheme performs joint sparse representation calculation on both modalities and the resultant tracking results are fused using min operation on the sparse representation coefficients. In addition, a co-learning approach is proposed to update the reference templates of both modality and enhance the tracking robustness. The proposed fusion scheme outperforms state-of-the-art approaches, and its effectiveness is verified using OTCBVS database.

关键词： joint sparse representation fusion tracking color image infrared image