Heuristics for the traveling repairman problem with profits

In the traveling repairman problem with profits, a repairman (also known as the server) visits a subset of nodes in order to collect time-dependent profits. The objective consists of maximizing the total collected revenue. We restrict our study to the case of a single server with nodes located in the Euclidean plane. We investigate properties of this problem, and we derive a mathematical model assuming that the number of visited nodes is known in advance. We describe a tabu search algorithm with multiple neighborhoods, and we test its performance by running it on instances based on TSPLIB. We conclude that the tabu search algorithm finds good-quality solutions fast, even for large instances

Integrated Decision Support System – iDSS for Library Holistic Evaluation

The decision-making process in academic libraries is paramount; however highly complicated due to the large number of data sources, processes and high volumes of data to be analyzed. Academic libraries are accustomed to producing and gathering a vast amount of statistics about their collection and services. Typical data sources include integrated library systems, library portals and online catalogues, systems of consortiums, quality surveys and university management. Unfortunately, these heterogeneous data sources are only partially used for decision-making processes due to the wide variety of formats, standards and technologies, as well as the lack of efficient methods of integration. This article presents the analysis and design of an integrated decision support system for an academic library. Firstly, a holistic approach documented in a previous study is used for data collection. This holistic approach incorporates key elements including process analysis, quality estimation, information relevance and user interaction that may influence a library’s decision. Based on the mentioned approach above, this study defines a set of queries of interest to be issued against the integrated system proposed. Then, relevant data sources, formats and connectivity requirements for a particular example are identified. Next, data warehouse architecture is proposed to integrate, process, and store the collected data transparently. Eventually, the stored data are analyzed through reporting techniques such as on-line analytical processing tools. By doing so, the article provides the design of an integrated solution that assists library managers to make tactical decisions about the optimal use and leverage of their resources and services

A critical review of multi-hole drilling path optimization

Hole drilling is one of the major basic operations in part manufacturing. It follows without surprise then that the optimization of this process is of great importance when trying to minimize the total financial and environmental cost of part manufacturing. In multi-hole drilling, 70% of the total process time is spent in tool movement and tool switching. Therefore, toolpath optimization in particular has attracted significant attention in cost minimization. This paper critically reviews research publications on drilling path optimization. In particular, this review focuses on three aspects; problem modeling, objective functions, and optimization algorithms. We conclude that most papers being published on hole drilling are simply basic Traveling Salesman Problems (TSP) for which extremely powerful heuristics exist and for which source code is readily available. Therefore, it is remarkable that many researchers continue developing novel metaheuristics for hole drilling without properly situating those approaches in the larger TSP literature. Consequently, more challenging hole drilling applications that are modeled by the Precedence Constrained TSP or hole drilling with sequence dependent drilling times do not receivemuch research focus. Sadly, these many low quality hole drilling research publications drown out the occasional high quality papers that describe specific problematic problem constraints or objective functions. It is our hope through this review paper that researchers' efforts can be refocused on these problem aspects in order to minimize production costs in the general sense

A BRANCH-AND-BOUND INTEGRATED SIMULATED ANNEALING ALGORITHM FOR THE ELECTRIC VEHICLE ROUTING PROBLEM WITH TIME WINDOWS

This paper addresses the electric vehicle routing problem with time windows (EVRPTW) which is one of the more recent research fields investigating the use of electric vehicle technology efficiently in logistics activities. In addition to the traditional vehicle routing problem, the EVRPTW considers the battery capacities of the electric vehicles and their charging operations while satisfying vehicle weight capacity and time windows constraints. The aim of the problem is to find the best route plan for the electric vehicles that minimizes the total distance travelled by the fleet. Due to the limited cruising range of the electric vehicles, the charging operations directly affect the routing plans. Therefore, the visiting time of the electric vehicles to the charging stations in a route has to be planned efficiently. In this context, this paper proposes a simulated annealing algorithm integrated with a branch-and-bound based station inserting operation which inserts the charging stations in a feasible route consisting of customer locations by searching the candidate insertions based on a branching concept. Distinctly from the heuristic based insertion operations the branch-and-bound based station insertion mechanism has the potential to find the best charging station insertion plan for the routes. In computational studies the proposed approach is tested on a benchmark data set, which is formed for the EVRPTW, and the results are compared with the solutions given by existing studies in literature and CPLEX solutions obtained with two hour time limitation. Comparisons show that the proposed algorithm is capable to find good result for the considered EVRPTW instances in smaller computational time.status: publishe

LIBER Quarterly

TDABC is a relatively new costing management technique, initially developed for manufacturing processes, which is gaining attention in libraries. This is because TDABC is a fast and simple method that only requires two parameters, an estimation of time required to perform an activity and the unit cost per time of supplying capacity. A few case studies have been documented with regard to TDABC in libraries; all of them being oriented to analyse specific library activities such as inter-library loan, acquisition and circulation processes. The primary focus of this paper is to describe TDABC implementation in one of the most important library processes, namely cataloguing. In particular, original and copy cataloguing are analysed through a case study to demonstrate the applicability and usefulness of TDABC to perform cost analysis of cataloguing processes.volumen 23; número

Definitie van robuustheid van een spoorwegdienstregeling

status: publishe