During the late incubation period or initial phase of dengue virus infection,laboratory confirmation is through viral isolation in cell culture and/or molecular investigations, or immunofluorescence,or immunohistochem...During the late incubation period or initial phase of dengue virus infection,laboratory confirmation is through viral isolation in cell culture and/or molecular investigations, or immunofluorescence,or immunohistochemistry[1].The dengue virus non-structural antigen NSl that would develop before the appearance of dengue IgM and/or IgG is emerging as a suitable option for dengue diagnosis[2].Platelet therapy is a standard clinical practice for dengue patients with severe thrombocytopenia[3].However,during introductory screening,platelet count is not being done in many cases. This results in delays of platelet therapy. In the course of the current(2010) spurt of dengue in New Delhi[4],simultaneous screening for NSl,IgM and IgG and platelet enumeration has been introduced at the展开更多
Despite extensive research on R-trees, most of the proposed schemes have notbeen integrated into existing DBMS owing to the lack of protocols of concurrency control. R-linktree is an acceptable data structure to deal ...Despite extensive research on R-trees, most of the proposed schemes have notbeen integrated into existing DBMS owing to the lack of protocols of concurrency control. R-linktree is an acceptable data structure to deal with this issue, but problems like phantom still exist.In this paper, we focus on a conflict detection scheme based on R-link tree for completeconcurrency control. An in-memory operation control list is designed to suspend conflictingoperations . The main features of this approach are (1) it can be implemented easily and does notneed any extra information ; (2) No deadlocks are involved in locking scheme ; (3) Non-conflictingoperations are not restricted ; and (4) Phantom problems in R-link tree are avoided throughbeforehand predication . The experiment results show that this scheme is correct and gains bettersystem performance.展开更多
Worst-case execution time (WCET) analysis of multi-threaded software is still a challenge. This comes mainly from the fact that synchronization has to be taken into account. In this paper, we focus on this issue and o...Worst-case execution time (WCET) analysis of multi-threaded software is still a challenge. This comes mainly from the fact that synchronization has to be taken into account. In this paper, we focus on this issue and on automatically calculating and incorporating stalling times (e.g. caused by lock contention) in a generic graph model. The idea that thread interleavings can be studied with a matrix calculus is novel in this research area. Our sparse matrix representations of the program are manipulated using an extended Kronecker algebra. The resulting graph represents multi-threaded programs similar as CFGs do for sequential programs. With this graph model, we are able to calculate the WCET of multi-threaded concurrent programs including stalling times which are due to synchronization. We employ a generating function-based approach for setting up data flow equations which are solved by well-known elimination-based dataflow analysis methods or an off-the-shelf equation solver. The WCET of multi-threaded programs can finally be calculated with a non-linear function solver.展开更多
随着区块链技术应用的普及,联盟链Hyperledger Fabric(简称Fabric)已成为知名区块链开源平台,并得到广泛关注.然而Fabric仍受困于并发事务间冲突问题,冲突发生时会引发大量无效交易上链,导致吞吐量下降,阻碍其发展.对于该问题,现有面向...随着区块链技术应用的普及,联盟链Hyperledger Fabric(简称Fabric)已成为知名区块链开源平台,并得到广泛关注.然而Fabric仍受困于并发事务间冲突问题,冲突发生时会引发大量无效交易上链,导致吞吐量下降,阻碍其发展.对于该问题,现有面向块内冲突的方案缺乏高效的冲突检测和避免方法,同时现有研究往往忽略区块间冲突对吞吐量的不利影响.提出了一种Fabric的优化方案Fabric-HT(fabric with high throughput),从区块内和区块间2方面入手,有效降低事务间并发冲突和提高系统吞吐量.针对区块内事务冲突,提出了一种事务调度机制,根据块内冲突事务集定义了一种高效数据结构——依赖关系链,识别具有“危险结构”的事务并提前中止,合理调度事务和消除冲突;针对区块间事务冲突,将冲突事务检测提前至排序节点完成,建立以“推送-匹配”为核心的冲突事务早期避免机制.在多场景下开展大量实验,结果表明Fabric-HT在吞吐量、事务中止率、事务平均执行时间、无效事务空间占用率等方面均优于对比方案.Fabric-HT吞吐量最高可达Fabric的9.51倍,是最新优化方案FabricSharp的1.18倍;空间利用率上相比FabricSharp提升了14%.此外,Fabric-HT也表现出较好的鲁棒性和抗攻击能力.展开更多
文摘During the late incubation period or initial phase of dengue virus infection,laboratory confirmation is through viral isolation in cell culture and/or molecular investigations, or immunofluorescence,or immunohistochemistry[1].The dengue virus non-structural antigen NSl that would develop before the appearance of dengue IgM and/or IgG is emerging as a suitable option for dengue diagnosis[2].Platelet therapy is a standard clinical practice for dengue patients with severe thrombocytopenia[3].However,during introductory screening,platelet count is not being done in many cases. This results in delays of platelet therapy. In the course of the current(2010) spurt of dengue in New Delhi[4],simultaneous screening for NSl,IgM and IgG and platelet enumeration has been introduced at the
文摘Despite extensive research on R-trees, most of the proposed schemes have notbeen integrated into existing DBMS owing to the lack of protocols of concurrency control. R-linktree is an acceptable data structure to deal with this issue, but problems like phantom still exist.In this paper, we focus on a conflict detection scheme based on R-link tree for completeconcurrency control. An in-memory operation control list is designed to suspend conflictingoperations . The main features of this approach are (1) it can be implemented easily and does notneed any extra information ; (2) No deadlocks are involved in locking scheme ; (3) Non-conflictingoperations are not restricted ; and (4) Phantom problems in R-link tree are avoided throughbeforehand predication . The experiment results show that this scheme is correct and gains bettersystem performance.
文摘Worst-case execution time (WCET) analysis of multi-threaded software is still a challenge. This comes mainly from the fact that synchronization has to be taken into account. In this paper, we focus on this issue and on automatically calculating and incorporating stalling times (e.g. caused by lock contention) in a generic graph model. The idea that thread interleavings can be studied with a matrix calculus is novel in this research area. Our sparse matrix representations of the program are manipulated using an extended Kronecker algebra. The resulting graph represents multi-threaded programs similar as CFGs do for sequential programs. With this graph model, we are able to calculate the WCET of multi-threaded concurrent programs including stalling times which are due to synchronization. We employ a generating function-based approach for setting up data flow equations which are solved by well-known elimination-based dataflow analysis methods or an off-the-shelf equation solver. The WCET of multi-threaded programs can finally be calculated with a non-linear function solver.
文摘随着区块链技术应用的普及,联盟链Hyperledger Fabric(简称Fabric)已成为知名区块链开源平台,并得到广泛关注.然而Fabric仍受困于并发事务间冲突问题,冲突发生时会引发大量无效交易上链,导致吞吐量下降,阻碍其发展.对于该问题,现有面向块内冲突的方案缺乏高效的冲突检测和避免方法,同时现有研究往往忽略区块间冲突对吞吐量的不利影响.提出了一种Fabric的优化方案Fabric-HT(fabric with high throughput),从区块内和区块间2方面入手,有效降低事务间并发冲突和提高系统吞吐量.针对区块内事务冲突,提出了一种事务调度机制,根据块内冲突事务集定义了一种高效数据结构——依赖关系链,识别具有“危险结构”的事务并提前中止,合理调度事务和消除冲突;针对区块间事务冲突,将冲突事务检测提前至排序节点完成,建立以“推送-匹配”为核心的冲突事务早期避免机制.在多场景下开展大量实验,结果表明Fabric-HT在吞吐量、事务中止率、事务平均执行时间、无效事务空间占用率等方面均优于对比方案.Fabric-HT吞吐量最高可达Fabric的9.51倍,是最新优化方案FabricSharp的1.18倍;空间利用率上相比FabricSharp提升了14%.此外,Fabric-HT也表现出较好的鲁棒性和抗攻击能力.
