5609348
Non-blocking message total ordering protocol
Message total ordering is a critical part in active replication in order to maintain consistency among members in a fault tolerant group. The paper proposes a non-blocking message total ordering protocol (NBTOP) for distributed systems. Non-blocking property refers to that the members in a fault tolerant group keep on running independently without waiting for installing the same group view when a fault tolerant group evolves even when decision messages collide. NBTOP takes advantage of token ring as its logical control way. Members adopt re-requesting mechanism (RR) to obtain their lost decisions. Forward acknowledgement mechanism (FA) is put forth to solve decision collisions. The paper further proves that NBTOP satisfies the properties of total order, agreement, and termination. NBTOP is implemented, and its performance test is done. Comparing with the performance of Totem, the results show that NBTOP has a better total ordering delay. It manifests that non-blocking property helps to improve protocol efficiency.
27110930
Solving the Group Priority Inversion Problem in a Timed Asynchronous System
Considers the priority inversion problem in an actively replicated system. Priority inversion was originally defined in the context of nonreplicated systems. Therefore, we first introduce the concept of group priority inversion, which extends the concept of (local) priority inversion to the context of a group of processors that perform an actively replicated processing. We then present the properties of a request scheduling protocol to enforce a total ordering for the processing of requests while avoiding group priority inversions. These properties have been implemented in a protocol that relies on a timed asynchronous system model equipped with a failure detector of the class /spl diams/S. The proposed solution allows us to replicate a critical server while ensuring that the processing of all the incoming requests is consistent (mechanisms for solving the atomic broadcast problem) and predictable (mechanisms for solving the group priority inversion problem). Thus, the described request scheduling protocol is a key component which can be used to develop fault-tolerant real-time applications in a timed asynchronous system.
7500432
A Method to Organize A Small-World Based Publish/Subscribe Network In Large-Scale Environment
The paper proposes a Small-World Network Publish/ Subscribe (SWN-P/S) model in large-scale environment, which is a novel Event-based Middleware with Small-World Network (SWN) model. Through connecting brokers into a small world network, SWN-P/S achieves both a strong local clustering and a small average path length among vast brokers. These characteristics help to spread information through the system more rapidly. The paper also put forwards a cloud-partition method to organize brokers in terms of clustering coefficient in SWN. The method is useful to reduce the amount of routing information stored in each broker and to accelerate information dissemination. Comparisons of SWN-P/S with other construction ways for Publish/Subscribe Event-based Middleware show that SWN-P/S is more suitable for building large-scale distributed systems.
15308955
Avoiding priority inversion on the processing of requests by active replicated servers
We consider the priority inversion problem in an actively replicated system. Priority inversion was originally defined in the context of non-replicated systems. Therefore we first introduce the concept of group priority inversion, which extends the concept of (local) priority inversion to the context of a group of processors that perform an actively replicated processing. We then present the properties of a request scheduling protocol to enforce a total ordering for the processing of requests while avoiding group priority inversions. These properties have been implemented in a protocol that relies on a timed asynchronous system model equipped with a failure detector of the class /spl square/S. The proposed solution allows one to replicate a critical server while ensuring that the processing of all the incoming requests is consistent (mechanisms for solving the atomic broadcast problem) and predictable (mechanisms for solving the group priority inversion problem). Thus, the described request scheduling protocol is a key component which can be used to develop fault tolerant real time applications in a timed asynchronous system.
6709613
A Nonblocking Approach for Reaching an Agreement on Request Total Orders
In distributed systems that use active replication to achieve robustness, it is important to efficiently enforce consistency among replicas. The nonblocking mode helps to speed up system execution. Unfortunately, this benefit comes at the expense of introducing decision conflicts when the replicas form a single logical token ring and client requests are processed in sequence following the ring. In order to reach an agreement regarding request total orders, this paper proposes a forward-confirmation (FC) approach to identify and solve decision conflicts when up to k successive replicas fail simultaneously. The FC approach can obtain consistent decisions among replicas. An implementation of the FC approach, namely, the queueing method, is proposed. Test results show that our protocol in the nonblocking mode outperforms the Totem protocol regarding delays and failure recovery.
17669846
Research on the Robustness of a Proportional Integral Switching Surface Based on Sliding Mode Control
In this paper, a novel proportional-integral (PI) switching surface is introduced for determining the synchronization performance of systems in the sliding mode motion. Based on the sliding mode controller, the system is established by a robust control scheme which guarantees the occurrence of a sliding motion of error states even when the parameter uncertainty and external disturbance are present. So this paper researches on robust synchronization problem by investigating a highly complex dynamic nonlinear system—chaotic systems. Some simulation results on controlling different chaotic systems are made and investigated in order to demonstrate the good performance of the method and this control design process is much easier to be completed.
14617194
Effects of Suffix Repetition Rates of a String on the Performance of String Matching Algorithms
The highly efficient Boyer-Moore’s string matching algorithm utilizes information on multi-occurrences of string suffixes in a pattern string to avoid backtracks in searching the pattern string. One hypothesis is that Boyer-Moore’s algorithm even benefits more from highly self-repetitive patterns. In this paper, the author studies how multi-occurrences of string suffixes affect the performance of the Boyer-Moore’s algorithm as well as some other well known string search algorithms. The paper introduces a new concept of suffix repetition rate (SRR) to measure how frequently the suffixes of a string occur inside of the string. Using this measurement, experiments with several thousands patterns over the entire range of SRRs have been carried out, and the results show that increasing of SRR on pattern strings does not improve the performance of a searching algorithm in terms of efficiency.
17622745
Automatic synthesis of multi-tasking implementations from real-time object-oriented models
Presents an approach towards the automatic synthesis of implementations from real-time object-oriented design models. From an application design model that addresses the functional requirements of the system, and given end-to-end timing requirements, our synthesis approach generates a feasible implementation model, i.e. one that will meet the timing requirements. The synthesis process is supported by automatic code generation that can take the application design model and the synthesized implementation model, and can generate code for the target platform. The synthesis of an implementation model is facilitated through the use of a generic (application-independent) implementation architecture, thereby reducing the synthesis problem to selecting a mapping of the application design model to the artifacts of the implementation architecture. In this paper, we use a multi-threaded event handling architecture with fixed event priorities. The synthesis problem then consists of determining priorities for events and mapping events to threads. We show how, given such a mapping, the response times can be analyzed, and then how, using the analysis, a feasible implementation model can be automatically synthesized.
35134245
Single Table Access Using Multiple Indexes: Optimization, Execution, and Concurrency Control Techniques
Many data base management systems' query optimizers choose at most one index for accessing the records of a table in a given query, even though many indexes may exist on the table. In spite of the fact that there are some systems which use multiple indexes, very little has been published about the concurrency control or query optimization implications (e.g., deciding how many indexes to use) of using multiple indexes. This paper addresses these issues and presents solutions to the associated problems. Techniques are presented for the efficient handling of record ID lists, elimination of some locking, and determination of how many and which indexes to use. The techniques are adaptive in the sense that the execution strategies may be modified at run-time (e.g., not use some indexes which were to have been used), if the assumptions made at optimization-time (e.g., about selectivities) turn out to be wrong. Opportunities for exploiting parallelism are also identified. A subset of our ideas have been implemented in IBM's DB2 V2R2 relational data base management system.
1211237
High Resolution Acquisition, Learning and Transfer of Dynamic 3D Facial Expressions
Synthesis and re-targeting of facial expressions is central to facial animation and often involves significant manual work in order to achieve realistic expressions, due to the difficulty of capturing high quality dynamic expression data. In this paper we address fundamental issues regarding the use of high quality dense 3-D data samples undergoing motions at video speeds, e.g. human facial expressions. In order to utilize such data for motion analysis and re-targeting, correspondences must be established between data in different frames of the same faces as well as between different faces. We present a data driven approach that consists of four parts: 1) High speed, high accuracy capture of moving faces without the use of markers, 2) Very precise tracking of facial motion using a multi-resolution deformable mesh, 3) A unified low dimensional mapping of dynamic facial motion that can separate expression style, and 4) Synthesis of novel expressions as a combination of expression styles. The accuracy and resolution of our method allows us to capture and track subtle expression details. The low dimensional representation of motion data in a unified embedding for all the subjects in the database allows for learning the most discriminating characteristics of each individual's expressions as that person's “expression style”. Thus new expressions can be synthesized, either as dynamic morphing between individuals, or as expression transfer from a source face to a target face, as demonstrated in a series of experiments. 
 
 
 
Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Animation; I.3.5 [Computer Graphics]: Curve, surface, solid, and object representations; I.3.3 [Computer Graphics]: Digitizing and scanning; I.2.10 [Artificial intelligence]: Motion ; I.2.10 [Artificial intelligence]: Representations, data structures, and transforms; I.2.10 [Artificial intelligence]: Shape; I.2.6 [Artificial intelligence]: Concept learning