Location-Aware Quality of Service Measurements for Service-Level Agreements

We add specifications of location-aware measurements to performance models in a compositional fashion, promoting precision in performance measurement design. Using immediate actions to send control signals between measurement components we are able to obtain more accurate measurements from our stochastic models without disturbing their structure. A software tool processes both the model and the measurement specifications to give response time distributions and quantiles, an essential calculation in determining satisfaction of service-level agreements (SLAs)

Applying Mean-Field Approximation to Continuous Time Markov Chains

The mean-field analysis technique is used to perform analysis of a system with a large number of components to determine the emergent deterministic behaviour and how this behaviour modifies when its parameters are perturbed. The computer science performance modelling and analysis community has found the mean-field method useful for modelling large-scale computer and communication networks. Applying mean-field analysis from the computer science perspective requires the following major steps: (1) describing how the agent populations evolve by means of a system of differential equations, (2) finding the emergent deterministic behaviour of the system by solving such differential equations, and (3) analysing properties of this behaviour. Depending on the system under analysis, performing these steps may become challenging. Often, modifications of the general idea are needed. In this tutorial we consider illustrating examples to discuss how the mean-field method is used in different application areas. Starting from the application of the classical technique, moving to cases where additional steps have to be used, such as systems with local communication. Finally, we illustrate the application of existing model checking analysis techniques

Serial Disk-based Analysis of Large Stochastic Models

The paper presents a survey of out-of-core methods available for the analysis of large Markov chains on single workstations. First, we discuss the main sparse matrix storage schemes and review iterative methods for the solution of systems of linear equations typically used in disk-based methods. Next, various out-of-core approaches for the steady state solution of CTMCs are described. In this context, serial out-ofcore algorithms are outlined and analysed with the help of their implementations. A comparison of time..

Invited “The Production of Nature: On Cyborgs, H20 and Spain’s Modernization Process”

The MoDeST Tool Environment (MOTOR) is a tool to facilitate the transformation, analysis and validation of modest models. modest is a modelling language to describe stochastic real-time systems. MOTOR implements the formal semantics of modest and is designed to transform and abstract modest specifications such that analysis can be carried out by third-party tools. For the time being, a fragment of MoDeST can be model-checked using CADP. The main analytical workhorse behind motor is discrete-event simulation, which is provided by the Möbius performance evaluation environment. We are experimenting with prototypical connections to the real-time model checker Uppaal.\u

The examination of marriage ritual among selected groups in South India

This thesis is concerned with variations in the traditional Hindu marriage ceremony as practiced by the several Tamil-speaking castes on the east coast of South India, The primary objective is to survey the descriptions of marriage ritual which are available in the current literature, rather than to attempt a sociological analysis of any particular problem. The intention has been to organize and examine the existing material with a view to additional field research in person in the near future. In the following pages we point out several significant differences in the nuptial rituals as they are performed at different levels in the caste hierarchy and these facts are interspersed with a discussion of the relation of the marriage ceremony to South Indian ritual in general. Because information on this topic is relatively abundant, the area to be considered in detail has been limited to three districts of Madras State: South Arcot, Tiruchirappalli and Thanjavur. Continued in thesis ...</p

Ten Years of Performance Evaluation for Concurrent Systems Using CADP

International audienceThis article comprehensively surveys the work accomplished during the past decade on an approach to analyze concurrent systems qualitatively and quantitatively, by combining functional verification and performance evaluation. This approach lays its foundations on semantic models, such as Imc (Interactive Markov Chain) and Ipc (Interactive Probabilistic Chain), at the crossroads of concurrency theory and mathematical statistics. To support the approach, a number of software tools have been devised and integrated within the Cadp (Construction and Analysis of Distributed Processes) toolbox. These tools provide various functionalities, ranging from state space generation (Cæsar and Exp.Open), state space minimization (Bcg Min and Determinator), numerical analysis (Bcg Steady and Bcg Transient), to simulation (Cunctator). Several applications of increasing complexity have been successfully handled using these tools, namely the Hubble telescope lifetime prediction, performance comparison of mutual exclusion protocols, the Scsi-2 bus arbitration protocol, the Send/Receive and Barrier primitives of Mpi (Message Passing Interface) implemented on a cache-coherent multiprocessor architecture, and the xSTream multiprocessor data-flow architecture for embedded multimedia streaming applications

Data Representation and Efficient Solution: A Decision Diagram Approach

Decision diagrams are a family of data structures that can compactly encode many functions on discrete structured domains, that is, domains that are the cross-product of finite sets. We present some important classes of decision diagrams and show how they can be effectively employed to derive “symbolic” algorithms for the analysis of large discrete-state models. In particular, we discuss both explicit and symbolic algorithms for state-space generation, CTL model-checking, and continuous-time Markov chain solution. We conclude with some suggestions for future research directions