A compensation cost analysis of service-aggregate transaction for DTNs clients

Clients from Delay Tolerant Networks (DTNs) might encounter overtime exceptions when they aggregate autonomic commercial web service references to form an all-or-nothing transaction. Such exceptions may cause extra overhead—“compensation cost” when aborting transactions. Regarding the delay-related characteristics of DTNs, this paper models the expected compensation cost (ECC) for the schedulings of commit-requests, presents a calculability analysis for quantitative ECC prediction, and explores the limitation of ECC’s probabilistic prediction accordingly. The analysis is based on the timed-2PC plus compensation (t2PC+) protocol and the multi-step price tag pattern, which is verified conditionally by simulation tests through randomly-chosen severely-fluctuant samplings of compensation cost and delays. The ultimate target of this work is to demonstrate the high complexity, and in particular, the uncertainty of ECC predictions due to the randomicity of DTNs’ delays.     

Guaranteed cost regulator design: A probabilistic solution and a randomized algorithm

This paper presents a gradient-based randomized algorithm to design a guaranteed cost regulator for a plant with general parametric uncertainties. The algorithm either provides with high confidence a probabilistic solution that satisfies the design specification with high probability for a randomly sampled uncertainty or claims that the feasible set of the design parameters is too small to contain a ball with a given radius. In both cases, the number of iterations executed in the algorithm is of polynomial order of the problem size and is independent of the dimension of the uncertainty.     

A factor-based probabilistic cost model to support bid-price estimation

An appropriate bid price is essential for winning a construction project contract. However, making an accurate cost estimate is both time-consuming and expensive. Thus, a method that does not take much time and can approximate a proper bid price can help a contractor in making bid-price decisions when the available bid-estimation time is insufficient. Such a method can also generate a target cost and provide a cross-check for their bid prices that were estimated using a detailed process. This study proposes a novel model for quickly making a bid-price estimation that integrates a probabilistic cost sub-model and a multi-factor evaluation sub-model. The cost sub-model, which is simulation-based, focuses on the cost divisions to save estimation time. At the same time, the multi-factor evaluation sub-model captures the specific factors affecting the cost of each cost division. The advantages of the proposed model are demonstrated by its application to three residential housing projects located in northern Taiwan. The steps for applying this model to other contractors are also provided.     

A cost analysis model for heavy equipment

Total cost is one of the most important factors for a heavy equipment product purchase decision. However, the different cost views and perspectives of performance expectations between the different involved stakeholders may cause customer relation problems between the manufacturers and customers. Beginning with the conventional manufacturers’ cost view, this paper presents the necessity and importance of expanding the heavy equipment manufacturers’ cost scope to include the post-manufacturing customer stage of their products. Then, this paper narrates a general mathematics Post-Manufacturing Product Cost (PMPC) model to analyze the total costs of heavy equipment in its utilization stage. A major emphasis of the PMPC model is placed on the strategy of improving the manufacturers product cost management and the strategy of customers purchasing decisions cost management and their interdependencies as related to their specific different perspectives on the product utilization patterns.     

基于PRA的网络安全风险评估模型

概率风险分析被广泛应用于社会各领域,如交通、能源、化工处理、航天、军事等。文章采用概率风险分析的方法,对网络的逻辑构成、网络攻击和攻击结果进行分析,通过故障树描述了网络系统被攻击的原因与途径,并建立了风险评估模型。     

A glimpse of symbolic-statistical modeling by PRISM

We give a brief overview of a logic-based symbolic modeling language PRISM which provides a unified approach to generative probabilistic models including Bayesian networks, hidden Markov models and probabilistic context free grammars. We include some experimental result with a probabilistic context free grammar extracted from the Penn Treebank. We also show EM learning of a probabilistic context free graph grammar as an example of exploring a new area.

A sensitivity formula for risk-sensitive cost and the actor–critic algorithm

We propose for risk sensitive control of finite Markov chains a counterpart of the popular ‘actor–critic’ algorithm for classical Markov decision processes. The algorithm is based on a ‘sensitivity formula’ for the risk sensitive cost and is shown to converge with probability one to the desired solution. The proof technique is an adaptation of the ordinary differential equations approach for the analysis of two time-scale stochastic approximation algorithms.     

Architecture analysis of enterprise systems modifiability - Models, analysis, and validation

Enterprise architecture (EA) models can be used in order to increase the general understanding of enterprise systems and to perform various kinds of analysis. This paper presents instantiated architectural models based on a metamodel for enterprise systems modifiability analysis, i.e. for assessing the cost of making changes to enterprise-wide systems. The instantiated architectural models detailed are based on 21 software change projects conducted at four large Nordic companies. Probabilistic relational models (PRMs) are used for formalizing the EA analysis approach. PRMs enable the combination of regular entity-relationship modeling aspects with means to perform enterprise architecture analysis under uncertainty. The modifiability metamodel employed in the analysis is validated with survey and workshop data (in total 110 experts were surveyed) and with the data collected in the 21 software change projects. Validation indicates that the modifiability metamodel contains the appropriate set of elements. It also indicates that the metamodel produces estimates within a 75% accuracy in 87% of the time and has a mean accuracy of 88% (when considering projects of 2000 man-hours or more).     

Real-time guaranteed cost control of MIMO networked control systems with packet disordering

This paper discusses guaranteed cost control for multi-input and multi-output (MIMO) networked control systems (NCSs) with multi-channel packet disordering. Considering the time-varying and bounded network transmission delay, packet dropout and packet disordering, a novel model of NCSs is proposed by introducing the concept of packet displacement. It is worthwhile mentioned that this model can fully describe the dynamic characteristic of network and always guarantee the newest control input executed by the plant, which makes that the plant can be controlled in real time. The resulting closed-loop systems are jump linear systems due to the newest signals executed subject to Markovian chains. A real-time controller is designed for uncertain and certain NCSs based on Markovian theory combined with linear matrix inequality (LMI) techniques such that the closed-loop cost function value is not more than a specified upper bound that varies according to Quality of Services (QOS). Finally, numerical examples are given to illustrate the effectiveness of the proposed method.     

A formal analysis of bluetooth device discovery

This paper presents a formal analysis of the device discovery phase of the Bluetooth wireless communication protocol. The performance of this process is the result of a complex interaction between several devices, some of which exhibit random behaviour. We use probabilistic model checking and, in particular, the tool PRISM to compute the best- and worst-case performance of device discovery: the expected time for the process to complete and the expected power consumption. We illustrate the utility of performing an exhaustive, low-level analysis to produce exact results in contrast to simulation techniques, where additional probabilistic assumptions must be made. We demonstrate an example of how seemingly innocuous assumptions can lead to incorrect performance estimations. We also analyse the effectiveness of improvements made between versions 1.1 and 1.2 of the Bluetooth specification.