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Vehicle-based GLOSA (Green Light Optimal Speed Advisory) systems use information about the next switching time of the traffic lights to calculate fuel-efficient position and velocity profiles for connected vehicles, according to their current state (position and speed). A stochastic optimal control problem was recently proposed to address the GLOSA problem in cases where the next switching time is decided in real time and is therefore uncertain in advance. The corresponding numerical solution via SDP (Stochastic Dynamic Programming) calls for substantial computational time (few minutes), which excludes problem solution in the vehicle’s computer in real time. This work considers the same stochastic problem of optimal trajectory specification for vehicles approaching a signalized junction with traffic signals operated in real-time (adaptive) mode, due to which the next switching time is stochastic. However, a modified version of Dynamic Programming, known as Discrete Differential Dynamic Programming (DDDP), is used for numerical solution of the stochastic optimal control problem. It is demonstrated, based on a realistic example, that the DDDP algorithm achieves results equivalent to those obtained with the ordinary SDP algorithm, albeit with significantly better performance in terms of computational time. Specifically, the solution is typically obtained in around 1 CPUs, which is real-time feasible and would allow for the DDDP calculations to be executed in the vehicle’s on-board computer.

The development of methodologies for bus priority at traffic signals is a research field that continues to grow since the need to improve public transport (PT) is nowadays higher compared to the previous decades. Several ways have been used to attract people to use PT means. These attempts can be distinguished in two basic categories: facility-design-based measures and signal-control-based measures. In this paper, a signal-control-based methodology is presented and implemented in a microscopic simulation environment emulating the network of Chania, Greece, with realistic traffic conditions. The control objective is to minimize the average delay time for the buses without creating major disturbances to the rest of the network. For this reason, apart from a fixed-time strategy combined with public transport priority (PTP), the traffic-responsive urban control (TUC) strategy with PTP is implemented in order to reduce the delays also for the private vehicles as well.

This paper investigates the application of real-time route diversion policies, with or without off-ramp closure, to address recurrent motorway traffic congestion created due to a saturated off-ramp. In particular, the proposed route diversion policies attempt to avoid the off-ramp queue spill-over onto the motorway mainstream and the resulting motorway congestion by re- routing the motorway vehicles through nearby off-ramps towards the same destination. This paper addresses the case where real-time route guidance strategies, based on user-optimum considerations, are not sufficient to resolve the spill-over and motorway congestion problem, which may call for harsh measures (off-ramp closure) to force route diversion; while other cases are treated in a companion paper. The proposed route diversion concepts are tested for a hypothetical, but quite typical network infrastructure and traffic scenario by use of macroscopic simulation. The obtained simulation results are compared to the case where no route diversion is employed, and reveal interesting features and the potential for significant improvements.

AbstractObjective:To determine the cost-effectiveness of vaccination against herpes zoster (HZ) and post-herpetic neuralgia (PHN) in individuals aged 60 years and older in Belgium.Methods:A Markov model was developed to compare the cost-effectiveness of vaccination with that of a policy of no vaccination. The model estimated the lifetime incidence and consequences of HZ and PHN using inputs derived from Belgian data, literature sources, and expert opinion. Cost-effectiveness was measured by the incremental cost-effectiveness ratio (ICER), expressed as cost per quality-adjusted life-year (QALY) gained.Results:Vaccination in individuals aged 60 years and older resulted in ICERs of €6,799 (third party payer perspective), €7,168 (healthcare perspective), and €7,137 (societal perspective). The number needed to vaccinate to prevent one case was 12 for HZ, and 35 or 36 for PHN depending on the definition used. Univariate sensitivity analyses produced ICERs of €4,959–19,052/QALY; duration of vaccine efficacy had the greatest impact on cost-effectiveness. Probabilistic sensitivity analysis showed at least a 94 probability of ICERs remaining below the unofficial €30,000 threshold.Discussion:Key strengths of the model are the combination of efficacy data from a pivotal clinical trial with country-specific epidemiological data and complete sensitivity analysis performed. Main limitations are the use of non country-specific PHN proportion and non Belgian disease-specific utilities. Results are comparable with those recently published.Conclusions:HZ vaccination in individuals aged 60 years and older would represent a cost-effective strategy in Belgium.

Electronic commerce is emerging as an important domain of integration and enhancement of more specific technologies and research efforts. It is clear that the role of WWW in this context is a cornerstone as the medium of information dissemination. A trend in e-commerce is to provide to the potential customers the ability to view and “try” the products in a persuasive 3D representation. We have designed and implemented a system for WWW enabled interactive design & visualization of a room, definition of pieces of furniture and placement of domestic appliances. The system conveys a generic approach for distributed creation and update of virtual worlds as means of interaction and information dissemination in an e-commerce context.

The problem of traffic congestion in modern day motorways calls for the design and implementation of efficient control strategies. It is argued in this paper that in order to have efficient, generic, and systematic solutions to a wide range of traffic control problems, macroscopic motorway traffic flow models in state-space form, that are relevant for the control problem and computationally non-intensive, are most appropriate. Such models allow the exploitation of available powerful, systematic, and theoretically supported automatic control concepts. Based on these concepts an Extended Kalman Filter for traffic state estimation, a multivariable LQI controller for coordinated ramp metering on a motorway stretch, and an integrated optimal control strategy for motorway networks are shortly presented. The criteria of a model's relevance for a given traffic control problem and its computational requirements are subsequently examined. Finally, the application of an advanced coordinated ramp metering control strategy, based on the optimal control approach, to the ring-road of Amsterdam, The Netherlands, is provided as an illustrative example.

This paper considers the problem of optimal water distribution to several retention reservoirs in an urban sewer network during rainfall. The goal of the control actions is the minimization of overflows and eventually the reduction of their polluting impact on receiving waters. Decomposition of the overall control task into a local‐flow control layer and a global coordinating control layer is assumed. For the global control task, a linear multivariable feedback regulator is developed via a systematic design procedure including a simplified model approach, a quadratic minimization criterion and subsequent application of the linear quadratic optimization method. The proposed control design guidelines facilitate quick and efficient regulator design for a broad class of sewer‐network control problems. A simulation study was performed for a particular network by use of an accurate hydrodynamic simulation model. Simulation results indicate significant overflow reductions achieved by the application of the multivariable controller as compared to fixed local control measures.

A macroscopic model is presented in this paper which describes the traffic flow on a freeway by a set of nonlinear, deterministic difference equations. The model is deduced from simple physical and empirical considerations and contains a set of free parameters which have to be identified using real traffic data. This model validation procedure is formulated here as a parameter optimization problem which is solved by nonlinear programming. In addition, model simplifications can be judged quantitatively my means of this validation procedure. The results demonstrate that the validated model copes surprisingly well with real traffic behaviour though there is a great part of stochastic events in traffic dynamics.

A multilayer control system for sewer networks combining optimal flow diversion for overflow minimization with moderate implementation cost is presented. The multilayer structuic consist s of an opt imizat ion layer, a direct control layer and an adaption layer. Control problems connected with these control layers are described. The discrete maximum principle and conjugate gradient techniques are applied for the solution of a simplified optimization problem for the overall network. Optimization results are used as reference trajectories for classical closed-loop control of individual subnetworks. Predicted inflow trajectories needed for the optimization procedure are provided by the adaptation layer.

A unifying review of four independently developed deterministic macroscopic control-oriented models of multi-lane freeway traffic is presented. It is shown that all models can be deduced from a common set of three basic laws of traffic flow: the conservation equation, the volume-density characteristic and the dynamics of the mean speed. Based on each of these models optimal control problems are formulated. Their efficiency in preventing or eliminating freeway traffic congestions is discussed in some detail. Concluding, a multilayer control structure as a base for an efficient form of practical freeway traffic control systems is outlined.

An optimal control approach to vehicle motion control in dynamic environments including moving obstacles is presented along with a numerical optimization algorithm for calculation of the optimal control trajectories. Low computation times allow for the solution of the optimal motion control problem to be effectuated on-line, via the rolling horizon concept, based on updated real-time measurements. The described approach provides high flexibility with respect to the vehicle model, the vehicle mission, and the motion constraints to be considered. Simulation examples demonstrate the efficiency of the approach in managing complicated conflict situations

This paper considers the application of a linear programming methodology for the computation of optimal control strategies in Wide Area Networks (WANs). In particular an existing flow model of traffic phenomena in WANs is expanded by additional consideration of propagation delays in the transmission lines and of finite storage capacities in the nodal buffers. On the basis of the expanded model, the integrated routing and congestion control problem in WANs is formulated as a linearly constrained, dynamic, discrete-time optimal control problem. For the computation of its solution, an algorithm which computes the solution of linear programming problems in the space of the optimization variables, is adapted to the structure of the large scale traffic problem in hand. The proposed algorithm provides the possibility of solving off-line more general traffic problems for WANs than the ones reported in the literature so far.

This paper presents an approach for the macroscopic modelling of traffic flow on large-scale motorway networks. First the utilised traffic flow model is presented, along with the additional concept of store-and-forward links. Then we describe the modelling of the large-scale motorway network around Amsterdam. The model validation, procedure and results based on real traffic measurements from the Amsterdam network are presented.

Design rules for control of water flow systems are applied to a particular control problem for a natural stream. Long distances between regulator gate and measurement location are considered. Application of PI control, a Smith predictor, and a nonlinear switching regulator are investigated. Comparison of control results is performed by use of a simulation model based on a simplified form of the St. Venant equations.

A macroscopic mathematical model of freeway traffic flow is applied to a 6 km-stretch of the Boulevard Périphérique in Paris including several on ramps and off-ramps. The model is validated on the basis of real traffic flow measurements selected under a broad spectrum of traffic conditions. A linearized version of the model is utilized for derivation of coordinated, feedback ramp metering strategies based on Linear Quadratic (LQ)-Optimisation theory . Efficiency of the presented strategy is tested by simulation means and compared to the no control case and to local control strategies. Nonlinear optimal control options are briefly discussed.

Local, traffic-responsive ramp metering is a wellknown control measure aiming at ameliorating traffic conditions on interurban or metropolitan freeways and motorways. A particular control strategy (ALINEA), the only local ramp metering strategy to be based on rigorous application of classical regulator theory, is presented, along with a low cost implementation concept. Field application of ALINEA and evaluation of its performance in France and The Netherlands confirm its clear superiority as compared to other popular approaches.

In this paper, we present a ship weather routeing procedure that minimises a fuel criterion. The minimisation algorithm is designed so as to enable the ship to respect her planned arrival time. Based on the dynamic programming procedure, in which the ship power is considered as an additional input variable, the method has been implemented using a simplified ship model and been tested on a tanker with different scenarios of the route weather conditions.

Asservissement Linéaire d'Entrée Autoroutière (ALINEA), a local feedback ramp-metering strategy, has had multiple field applications, and more applications are planned in several European countries. The main features of ALINEA are presented and the field results achieved to date at both single and multiple ramps of the Boulevard Périphérique in Paris and at the A10 West motorway in Amsterdam are summarized. The reported results indicate easy application, flexibility, and high efficiency of ALINEA. Planned implementations are outlined.

An optimal control strategy for combined sewer network control is formulated and tested with respect to several practical aspects like sensitivity to changing performance indices and different sample time intervals, impact of simplifications and inaccurate inflow predictions, and role of the optimization time horizon. Furthermore performance of the method is investigated for a broad class of inflow events and is compared to heuristic strategies. Results demonstrating the ability of the proposed strategy to handle the complex combined sewer network control problem are presented and discussed.

The paper develops a fairly general framework for derivation of control strategies applying to moving vehicles, such as mobile robots or robot arms, in a dynamically changing environment. The basic idea is to consider stochastic terms for any uncertain future environment change and to apply stochastic dynamic programming for control strategy development. The method permits consideration of a number of possible missions such as obstacle avoidance or obstacle hiting and/or moving forward or following a trajectory etc. A number of examples demonstrate that the developed control strategies are capable of taking efficient decisions in quite complicated conflict situations.

The paper presents a general state-space modeling approach for multiorigin multidestination freeway networks including several routes for each origin-destination pair. The problem of controlling variable direction signs at bifurcation locations so as to achieve system optimal or user optimal traffic conditions is formulated in control engineering terms. A number of well-known control strategies are suggested and tested by simulation means for a real medium-size freeway network.

Optimal control methods are applied to combined sewer systems in order to reduce pollution of receiving waters through maximum utilization of existing storage capacity. Because of the high dimension and complexity of the control problem, a multilayer methodology is proposed leading to a horizontal and vertical decentralization of the overall control structure. A constrained discrete dynamical optimal control problem for a simplified sewer network is solved on-line in the optimization layer using variational calculus and gradient techniques. Optimal state and control trajectories are used as reference trajectories for the local control of small subnetworks. Prediction of runoff-trajectories are provided by a supremal adaptation layer. Efficacy of the control system is demonstrated by application to the combined sewer system of the city of Munich.

A scalar Kalman filter is applied to traffic density estimation in a 500 m-long segment of Boulevard Périphérique in Paris using presence detector data. After derivation of the model and filter equations, estimates are compared to real traffic density measurements extracted from a film. Results indicate accuracy of estimates, excellent tracking capabilities, and low sensitivity with respect to changing application conditions.

An optimal control algorithm based on the discrete maximum principle is applied to regulate traffic flow on ringways by use of ramp metering.

This paper discusses and illustrates an optimization algorithm for ship weather routeing, based on dynamic programming. Contrary to classical implementation in weather routeing, it allows power variations. This algorithm is applied to several examples combining time and fuel minimizations, and compared with classical weather routeings. An empirical dynamic navigation model is used to show that classical weather routeing applications of dynamic programming could lead to sub-optimal routeing.

Trichoepitheliomas are benign skin tumors with follicular differentiation that present most commonly as solitary lesions. They can also present as multiple centrofacial papules due to several mutations in the CYLD gene. Multiple unilateral trichoepitheliomas in a linear or dermatomal distribution may rarely be seen. Herein, we report a case of multiple unilateral trichoepitheliomas on the face of a healthy 34-year-old woman of Caucasian origin.

Dem in den letzten Jahrzehnten verstärkt und verbreitet auftretenden Phänomen des Verkehrsstaus, der zur degradierten Nutzung der vorhandenen Verkehrsinfrastruktur führt, kann mittels geeigneter Steuerungsmaßnahmen wirksam begegnet werden. Dieser Übersichtsaufsatz befasst sich mit Steuerungs- und Regelungsproblemen und entsprechenden -strategien für die Bereiche des städtischen Verkehrs, des Schnellstraßenverkehrs und der Routenführungs- und -informationssysteme mit Schwerpunkt auf die Anwendung bekannter, systematischer Optimierungs- und Regelungsverfahren. Vergangene und gegenwärtige Probleme und Entwicklungen sowie zukünftige Herausforderungen werden aufgegriffen und kommentiert.

Research carried out in 1964–65 at the “Democritus“ Nuclear Research Center has ascertained that when pupae of the olive fruit fly, Dacus oleae (Gmelin), are exposed to 8, 10, and 12 krad of gamma rays, permanent dominant lethality is caused to sperm to a degree which can be considered satisfactory for practical purposes. It has shown also that 6 krad was a satisfactory male-sterilizing dose. At these doses not more than 2.6% of the progeny of irradiated males mated with normal females reached the first larval instara, and not more than 0.3% reached the pupal stage, as compared with 82.3% and 41.4% in the control, respectively. The same doses caused permanent sterility to the irradiated females. They did not substantially affect the time or the percent of adult emergence, or the longevity of irradiated males.