Application of Kalman filtering to demographic models

In this paper demographic systems appear as stochastic and unstable linear systems. Their state representation model is simulated and identified using Kalman filtering. The example of the French beef cattle herd is presented and results are discussed with emphasis on their agroeconomic meaning.     

Psychological services in jails.

Points out that the development of psychological services in jails is relatively recent. The present authors describe, under the headings of assessment, crisis intervention/short-term counseling, group programs, and research, the psychological services that are currently being provided in these settings. Examples of these types of services are drawn from programs operating in the jails and regional detention centers in the Eastern Region of the Ministry of Correctional Services, Ontario. The authors note that a provincial correctional agency, with a strong regional emphasis, has provided the best conditions for the development of psychological services in jails. (French abstract) (11 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Solving an integrated employee timetabling and job-shop scheduling problem via hybrid branch-and-bound

We propose exact hybrid methods based on integer linear programming (ILP) and constraint programming (CP) for an integrated employee timetabling and job-shop scheduling problem. Each method we investigate uses a CP formulation associated with an LP relaxation. Under a CP framework, the LP relaxation is integrated into a global constraint using in addition reduced cost-based filtering techniques. We propose two CP formulations of the problem yielding two different LP relaxations. The first formulation is based on a direct representation of the problem. The second formulation is based on a decomposition in intervals of the possible operation starting times. We show the theoretical interest of the decomposition-based representation compared to the direct representation through the analysis of dominant schedules. Computational experiments on a set of randomly generated instances confirm the superiority of the decomposition-based representation. In both cases, the hybrid methods outperform pure CP for employee cost minimization while it is not the case for makespan minimization. The experiments also investigate the interest of the proposed integrated method compared to a sequential approach and show its potential for multiobjective optimization.     

Topology-aware wavelength partitioning for DWDM OBS networks: A novel approach for absolute QoS provisioning

Optical Burst Switching (OBS) is a promising switching technology for the next generation all-optical networks. An OBS network without wavelength converters and fiber delay lines can be implemented simply and cost-effectively using the existing technology. However, this kind of networks suffers from a relatively high burst loss probability at the OBS core nodes. To overcome this issue and consolidate OBS networks with QoS provisioning capabilities, we propose a wavelength partitioning approach, called Optimization-based Topology-aware Wavelength Partitioning approach (OTWP). OTWP formulates the wavelength partitioning problem, based on the topology of the network, as an Integer Linear Programming (ILP) model and uses a tabu search algorithm (TS) to resolve large instances efficiently. We use OTWP to develop an absolute QoS differentiation scheme, called Absolute Fair Quality of service Differentiation scheme (AFQD). AFQD is the first absolute QoS provisioning scheme that guarantees loss-free transmission for high priority traffic, inside the OBS network, regardless of its topology. Also, we use OTWP to develop a wavelength assignment scheme, called Best Effort Traffic Wavelength Assignment scheme (BETWA). BETWA aims to reduce loss probability for best effort traffic. To make AFQD adaptive to non-uniform traffic, we develop a wavelength borrowing protocol, called Wavelength Borrowing Protocol (WBP). Numerical results show the effectiveness of the proposed tabu search algorithm to resolve large instances of the partitioning problem. Also, simulation results, using ns-2, show that: (a) AFQD provides an excellent quality of service differentiation; (b) BETWA substantially decreases the loss probability of best effort traffic to a remarkably low level for the OBS network under study; and (c) WBP makes AFQD adaptive to non-uniform traffic by reducing efficiently blocking probability for high priority traffic.     

A hybrid genetic algorithm with adaptive diversity management for a large class of vehicle routing problems with time-windows

The paper presents an efficient Hybrid Genetic Search with Advanced Diversity Control for a large class of time-constrained vehicle routing problems, introducing several new features to manage the temporal dimension. New move evaluation techniques are proposed, accounting for penalized infeasible solutions with respect to time-window and duration constraints, and allowing to evaluate moves from any classical neighbourhood based on arc or node exchanges in amortized constant time. Furthermore, geometric and structural problem decompositions are developed to address efficiently large problems. The proposed algorithm outperforms all current state-of-the-art approaches on classical literature benchmark instances for any combination of periodic, multi-depot, site-dependent, and duration-constrained vehicle routing problem with time windows.     

An integration of production management rules and fabrication know-how for real-time cell production control

Between the steps of operation release and process control of the production activity control, no re-evaluation of the production organization is undertaken. However, the production organization can be technically optimized or modified. This level of production management is difficult to achieve, essentially because several fields come into play. It becomes apparent, however, that it is essential to integrate production management and production cell control in order to obtain advanced production systems which are more ‘reactive’ to technical and economic perturbations. In this paper, a contribution to the resolution of this problems is presented and the following ideas are introduced:

1. a control structure of production cells within “real-time production management functions”,

2. a control strategy of the cells by “scénario de production” (production scenario).

First of all, the functions of this control structure are described and then the principles of its generic utilization for the control of a complex production system are given. An executable production scenario is conceived according to the production management rules, the data and know-how of the fabricators also play a role. The last section of this paper describes, using an industrial example in the field of sub-contracted machining, the construction of such a scenario.     

Bi‐objective stochastic programming models for determining depot locations in disaster relief operations

This paper presents two‐stage bi‐objective stochastic programming models for disaster relief operations. We consider a problem that occurs in the aftermath of a natural disaster: a transportation system for supplying disaster victims with relief goods must be established. We propose bi‐objective optimization models with a monetary objective and humanitarian objective. Uncertainty in the accessibility of the road network is modeled by a discrete set of scenarios. The key features of our model are the determination of locations for intermediate depots and acquisition of vehicles. Several model variants are considered. First, the operating budget can be fixed at the first stage for all possible scenarios or determined for each scenario at the second stage. Second, the assignment of vehicles to a depot can be either fixed or free. Third, we compare a heterogeneous vehicle fleet to a homogeneous fleet. We study the impact of the variants on the solutions. The set of Pareto‐optimal solutions is computed by applying the adaptive Epsilon‐constraint method. We solve the deterministic equivalents of the two‐stage stochastic programs using the MIP‐solver CPLEX.     

Heuristics for the mixed swapping problem

In the swapping problem, to each vertex of a complete directed graph are associated at most two object types representing its supply and demand. It is assumed that for each object type the total supply equals the total demand. A vehicle of unit capacity, starting and ending its route at an arbitrary vertex, is available to carry the objects along the arcs of the graph. The aim is to determine a minimum cost route such that each supply and demand is satisfied. When some of the object types are allowed to be temporarily unloaded at some intermediate vertices before being carried to their final destination, the problem is called the mixed swapping problem. In this paper we describe constructive and improvement heuristics which were successfully applied to randomly generated instances with up to 10,000 vertices, with an average optimality gap not exceeding 1%.     

Optimizing routing in packet-switched networks with non-Poisson offered traffic

Routing models for packet-switched networks have traditionally been based on the assumption that the offered traffic is Poisson. This is unrealistic since for many applications, real life data streams tend to be extremely bursty, contradicting the Poisson assumption. This paper introduces a centralized bifurcated routing optimization model for networks with significantly non-Poisson offered traffic. The central purpose of the work is to assess the impact of non-Poisson traffic on routing algorithm developed for Poisson flows. A systematic testing plan for networks with a simple topology and variable levels of capacity, demand and packet length was designed. The results confirmed that Poisson delay formulas together with classical Poisson routing are not appropriate when significant demand is highly variable. The results also show that non-Poisson delay formulas are crucial to the assessment of average delay in these cases.