Congestion management in traffic-light intersections via Infinitesimal Perturbation Analysis

We present a flow-control technique in traffic-light intersections, aiming at regulating queue lengths to given reference setpoints. The technique is based on multivariable integrators with adaptive gains, computed at each control cycle by assessing the IPA gradients of the plant functions. Moreover, the IPA gradients are computable on-line despite the absence of detailed models of the traffic flows. The technique is applied to a two-intersection system where it exhibits robustness with respect to modeling uncertainties and computing errors, thereby permitting us to simplify the on-line computations perhaps at the expense of accuracy while achieving the desired tracking. We compare, by simulation, the performance of a centralized, joint two-intersection control with distributed control of each intersection separately, and show similar performance of the two control schemes for a range of parameters

SNUS-2.5, a Multimoment Analysis of Road Demand, Accidents and their Severity in Germany, 1968 – 1989

The present article presents an improved and refined version of the SNUS-1 model (GAUDRY and BLUM 1993) documented only in French. The greatest difficulty faced in the development of the model did not have to do with structure – the multilevel structure is straightforward – but with the specification of the employment activity variable, due to the specifics of the German economy,and with the proper formulation of the role of vehicle stocks in the road demand models. Moreover,we consider the following aspects to be special in the context of an analysis of Germany: • there exist no general speed limits on motorways, i.e. about 70% allow unlimited speed today,and in the Sixties, when our analysis starts, this share was even higher; • the country is large compared with other regions were the DRAG-methodology is employed, and it possesses high car ownership levels and an important car industry that sees the German infrastructure as an appropriate testing ground; • Germany is poly-central, its infrastructure resembles a grid, whereas France’s is almost a huband-spoke system, as compared for instance to Norway’s line; • unification is not yet included because of lagging data availability and, thus, problems to compensate for the structural break in data series.Classification-JEL:

Multimodal person recognition for human-vehicle interaction

Next-generation vehicles will undoubtedly feature biometric person recognition as part of an effort to improve the driving experience. Today's technology prevents such systems from operating satisfactorily under adverse conditions. A proposed framework for achieving person recognition successfully combines different biometric modalities, borne out in two case studies

Adaptive Importance Sampling for Performance Evaluation and Parameter Optimization of Communication Systems

We present new adaptive importance sampling techniques based on stochastic Newton recursions. Their applicability to the performance evaluation of communication systems is studied. Besides bit-error rate (BER) estimation, the techniques are used for system parameter optimization. Two system models that are analytically tractable are employed to demonstrate the validity of the techniques. As an application to situations that are analytically intractable and numerically intensive, the influence of crosstalk in a wavelength-division multiplexing (WDM) crossconnect is assessed. In order to consider a realistic system model, optimal setting of thresholds in the detector is carried out while estimating error rate performances. Resulting BER estimates indicate that the tolerable crosstalk levels are significantly higher than predicted in the literature. This finding has a strong impact on the design of WDM networks. Power penalties induced by the addition of channels can also be accurately predicted in short run-time

A comprehensive literature classification of simulation optimisation methods

Simulation Optimization (SO) provides a structured approach to the system design and configuration when analytical expressions for input/output relationships are unavailable. Several excellent surveys have been written on this topic. Each survey concentrates on only few classification criteria. This paper presents a literature survey with all classification criteria on techniques for SO according to the problem of characteristics such as shape of the response surface (global as compared to local optimization), objective functions (single or multiple objectives) and parameter spaces (discrete or continuous parameters). The survey focuses specifically on the SO problem that involves single per-formance measureSimulation Optimization, classification methods, literature survey

Aeronautical Engineering: A special bibliography with indexes, supplement 64, December 1975

This bibliography lists 288 reports, articles, and other documents introduced into the NASA scientific and technical information system in November 1975