18359442
General Approach for Simulating Heterogeneity of Car-Following Behaviors
This paper presents a general approach to simulate heterogeneity of car-following behaviors in freeway traffic. This is achieved by proposing a new car-following model called General Individual Based car-following Model (GIBM) which takes into account the characteristics of the individual driver. The model parameters are expressed as functions with regard to “aggressiveness level” of drivers. The numerical simulation of the perturbation propagation in dense traffic flow by using the GIBM shows that small perturbations could develop into stable moving jams, growing moving jam, and decaying moving jams randomly, due to the heterogeneity of individual car-following behaviors in traffic flow. The result of the simulation is consistent with the empirical observation. The GIBM appears promising for application to microscopic simulations of traffic dynamics including randomness. It presents a general approach to simulate the heterogeneity of car-following behaviors efficiently and simply.
15004157
A Semantic QoS-Aware Discovery Framework for Web Services
Augmenting web services with explicit semantics forms the foundation of Service Oriented Architectures (SOAs) automation. As more and more Semantic Web Services (SWSs) are deployed, similar SWSs could have quite different quality-of-service (QoS) levels. The QoS-aware discovery becomes an important challenge. While some efforts try to solve it via Constraint Programming (CP), they suffer from the purely syntactic matchmaking method. Furthermore, the construction of constraints and the selection of services are completely dependent on the literal translation from QoS descriptions, which increase obstacles to actually apply CP. In this paper, we propose a semantic QoS-aware framework for SWSs discovery by combining the semantic matchmaking and CP. Initially, a QoS ontology is presented to define QoS data into service descriptions. Then the ontology reasoning is adopted to change previous syntactic matchmaking into a semantic way. Through confirming the compatibility of concepts, complex QoS conditions are solved as constraints and a selection algorithm is proposed to obtain the optimal offer. Finally, the prototype implementation of our framework is discussed and a SWSs discovery case is used to illustrate the comprehensive discovery process.
10702245
A wireless LAN-based indoor positioning technology
Context-aware computing is an emerging computing paradigm that can provide new or improved services by exploiting user context information. In this paper, we present a wireless-local-area-network-based (WLAN-based) indoor positioning technology. The wireless device deploys a position-determination model to gather location information from collected WLAN signals. A model-based signal distribution training scheme is proposed to trade off the accuracy of signal distribution and training workload. A tracking-assistant positioning algorithm is presented to employ knowledge of the area topology to assist the procedure of position determination. We have set up a positioning system at the IBM China Research Laboratory. Our experimental results indicate an accuracy of 2 m with a 90% probability for static devices and, for moving (walking) devices, an accuracy of 5 m with a 90% probability. Moreover, the complexity of the training procedure is greatly reduced compared with other positioning algorithms.
14513982
An Online Model Checking Tool for Safety and Liveness Bugs
Modern software model checkers are usually used to find safety violations. However, checking liveness properties can offer a more natural and effective way to detect errors, particularly in complex concurrent and distributed e-business systems. Specifying global liveness properties which should always eventually be true proves to be more desirable, but it is hard for existing software model checkers to verify liveness in real codes because doing so requires finding an infinite execution. For solving such a challenge, this paper proposes an online checking tool to verify the safety and liveness properties of complex systems. We adopt the linear temporal logic to describe the semantics of the finite model checking, use binary instrumentation to obtain the distribute states and apply a checking engine to dynamically verify the finite trace linear temporal logic properties. At last, we demonstrate the method in a distributed system using distributed protocol Paxos and achieve good results by experiments.
5812455
Knowledge Enhanced IT Service Management
To manage the increasing complexity of IT systems and align IT services with business is the main theme of IT Service Management (ITSM). Current ITSM architecture adopts ITU as the framework to integrate silos of operational management tools and configuration information to build an end-to-end solution based on best practices. However, it lacks of a systematic means to address an important aspect of IT operation, i.e., managing the knowledge separated in various tools and experts' minds. In this paper, a novel knowledge-enhanced architecture is proposed to improve the effectiveness and efficiency of ITSM. The essential contribution of this novel architecture is to involve a Knowledge Management Database (KMDB) which provides assistance for knowledge capture, mining, storage and sharing. The paper will discuss an approach of how to construct such a KMDB with motivating scenarios and detailed description of key components. To validate the approach, a prototype system is developed and evaluated by being applied for problem analysis on a Cisco Voice over IP (VoIP) system. The experiment results show a remarkable improvement in the effectiveness and efficiency for practical IT service management operations.
12111515
Algorithm of integrating QFD and TRIZ for the innovative design process
TRIZ, the Russian acronym of the Theory of Inventive Problem Solving, is a useful tool that can solve the problem of "how to do" effectively in the innovative design process, while QFD (Quality Function Deployment) is able to settle the problem of "what to do". Although the potential of using both QFD and TRIZ in the product design process is huge, there are little tools to integrate these two methods effectively. In this research, we describe an algorithm that can integrate QFD and TRIZ effectively for the purpose of the innovative design process. The core of the algorithm is to identify the contradictions in TRIZ by defining rules based on HOQ (House of Quality) in QFD. A software tool called TRIZmatrix is developed based on this algorithm. Application of the algorithm to the case of the airbag problem is studied in detail. The software application and the case study show the advantage of this algorithm for CAI (computer aided innovation) software development.
29040872
A Variant to Turing's Theory of Computing Machines
The principal purpose of this paper is to offer a theory which is closely related to Turing's [1] but is more economical in the basic operations. I t will be proved that a theoretically simple basic machine can be imagined and specified such tha t all partial recursive functions (and hence all solvable computation problems) can be computed by it and tha t only four basic types of instruction are employed for the programs: shift left one space, shift right one space, mark a blank space, conditional transfer. In particular, erasing is dispensable, one symbol for marking is sufficient, and one kind of transfer is enough. The reduction is somewhat similar to the realization of, for instance, the definability of conjunction and implication in terms of negation and disjunction, or of the definability of all these in terms of Sheffer's stroke function. As a result, i t becomes less direct to prove that certain things can be done by the machines, but a little easier to prove that certain things cannot be done. This serf-contained theory will b e presented, as far as possible, in a language which is familiar to those who are engaged in the use and construction of largescale computers. Turing's theory of computable functions antedated but has not much influenced the extensive actual construction of digital computers. These two aspects of theory and practice have been developed almost entirely independently of each other. The main reason is undoubtedly that logicians are interested in questions radically different from those with which the applied mathematicians and electrical engineers are primarily concerned. I t cannot, however, fail to strike one as rather strange that often the same concepts are expressed by very different terms in the two developments. One is even inclined to ask whether a rapprochement might not produce some good effect. This paper wiU, it is believed, be of use to those who wish to compare and connect the two approaches. Extensive use of Turing [1] and Kleene [2] (Chapter XI I I ) will be made, although the exposition is sufficient in itself.
6690308
PEPA Analysis of MAP Effects in Hierarchical Mobile IPv6
To overcome the drawbacks of the mobile IPv6 protocol on handling local mobility management, IETF proposed the HMIPv6 protocol which introduces an intermediate mobility anchor point (MAP) to hide the movement of a mobile node within a local area. However, the MAP forms a bottleneck in the network since all the traffic destined for its served nodes has to go through it. Most research on HMIPv6 focuses on protocol optimisation, and performance analysis of HMIPv6 is usually simulation-based. In this paper, we employ a performance evaluation formalism named PEPA to investigate the performance tradeoffs of MAPs in HMIPv6. Performance measures such as response time and MAP utilisation are presented.
8066461
Scalability of Hybrid Fuzzy C-Means Algorithm Based on Quantum-Behaved PSO
A new hybrid fuzzy clustering algorithm that incorporates the fuzzy c-means (FCM) into the quantum-behaved particle swarm optimization (QPSO) algorithm is proposed in this paper (QPSO+FCM). The QPSO has less parameters and higher convergent capability of the global optimizing than particle swarm optimization algorithm (PSO). So the iteration algorithm is replaced by the QPSO based on the gradient descent of FCM, which makes the algorithm have a strong global searching capacity and avoids the local minimum problems of FCM and in a large degree avoids depending on the initialization values. This paper also investigates the ability of FCM algorithm, PSO+FCM algorithm and GA+FCM algorithm with Iris testing data and Wine testing data. The simulation result proves that compared with other algorithms, the new algorithm not only has the favorable convergence but also has been obviously improved the clustering effect.
6929789
WSN02-2: Adaptive Network Resource Management in IEEE 802.11 Wireless Random Access MAC
Effective and efficient management of wireless network resources is attracting more and more research attention, due to the rapid growing deployment of wireless mesh and ad hoc networks and to the increasing demand for Quality of Service (QoS) support in these networks. This paper proposes an adaptive network resource management scheme in the popular IEEE 802.11 random access MAC by adaptively adjusting the minimum contention window sizes of traffic flows. First, a novel generalized processor sharing (GPS) model is presented for the IEEE 802.11 random access MAC revealing the relationship between the minimum contention window size of a traffic flow and the amount of network resource this flow can receive. Using this GPS MAC model, a feedback control system model for the proposed adaptive network resource management system is developed, by directly extending our previous work in wireline GPS networks. Based on the feedback control system model, adaptive P and adaptive PI controllers are designed, and their performances are studied in simulations. Simulation results show that by using the designed controllers, the proposed adaptive network resource management approach is able to provide guaranteed distinct QoS support to traffic flows.
4332805
Stable egress route selection for interdomain traffic engineering: model and analysis
We present a general model of interdomain route selection to study interdomain traffic engineering. In this model, the routing of multiple destinations can be coordinated. Thus the model can capture general traffic engineering behaviors such as load balancing and link capacity constraints. We first identify potential routing instability and inefficiency of interdomain traffic engineering. We then derive a sufficient condition to guarantee convergence. We also show that the constraints on local policies imposed by business considerations in the Internet can guarantee stability without global coordination. Using realistic Internet topology, we evaluate the extent to which routing instability of interdomain traffic engineering can happen when the constraints are violated