Proposed Analysis Approach Research Articles

Probabilistic Delay Model at Stop‐Controlled Intersection

Operating conditions at stop‐controlled approaches to highway intersections depend, to a large extent, on the gap‐acceptance behavior of motorists. Several researchers have previously proposed and demonstrated the application of discrete‐choice modeling techniques for predicting gap‐acceptance probabilities. The work described in this paper has used logit modeling to predict the probability that a randomly chosen motorist will accept a given gap in the conflicting traffic stream based upon characteristics of the gap. This gap‐acceptance function is then used in a stochastic queuing model to predict vehicle delay. The specific methodology presented in this paper is applicable to right‐turning traffic at a T‐intersection. Evaluation of the methodology using an empirical data set suggests that the proposed analysis approach offers significant potential. Issues related to extending the applicability and generality of the proposed methodology are briefly discussed in the conclusions of this paper.

Work flow methodology: A proposed approach for analysis and conceptual design of large scale computer based information systems

The objective of this paper is to explain our approach called “Work Flow Methodology for Analysis and Conceptual Data Base Design of Large Scale Computer Based Information System”. The user fills in, through the different steps of the methodology and in the light of the definition of dynamic adaptive system, a number of forms which relate the topological dimension to the time dimension for each application of a given system. In addition, we obtain the “Unit Subschema” which defines the responsibilities of issuing and authorization of receiving information at the proper time. Finally, we apply our methodology to the Registration System in Kuwait University.

Dependability modeling and evaluation of software fault-tolerant systems

Dependability modeling and evaluation (encompassing reliability and safety issues) of the two major fault tolerance software approaches-recovery blocks (RBs) and N version programming (NVP)-are presented. The study is based on the detailed analysis of software fault-tolerance architectures able to tolerate a single fault (RB: two alternates and an acceptance test; NVP: three versions and a decider). For each approach a detailed model based on the software production process is established and then simplified by assuming that only a single fault type may manifest during execution of the fault-tolerant software and that no error compensation may take place within the software. The analytical results obtained make it possible to identify the improvement, compared to a non-fault-tolerant software, that could result from the use of RB (the acceptance test has to be more reliable from the alternates) and NVP (related faults among the versions and the decider have to be minimized) and to determine the most critical types of related faults. Nested RBs are studied, showing that the proposed analysis approach can be applied to such realistic software structures and that when an alternate is itself an RB, the results are analogous to the case of the addition of a third alternate. The reliability analysis shows that only a small improvement can be expected. >