24 research outputs found
Order acceptance and scheduling policies for a make-to-order environment with family-dependent lead and batch setup times
Get PDF<p>In many make-to-order production situations with batch setup times, customer orders are grouped into family-dependent batches to limit the loss of capacity due to setups. These batches, however, cannot be too large, since the make-to-order character requires that orders have to be produced in time. This trade-off between setup time efficiency and due-date adherence creates a challenging scheduling problem referred to in the literature as the Customised Stochastic Lot Scheduling Problem. Typically, suppliers reduce the complexity of the production problem by quoting lead times that are equal for all customer families. This choice, however, is in many cases too restrictive. In this paper, we show quantitatively by means of Markov decision processes (MDPs) that using family-dependent lead times can result in a significant gain in profit as compared with using standard lead times. We develop a simple heuristic acceptance/scheduling policy, and demonstrate that this heuristic performs very well compared with the optimal policy of the MDP for a wide range of parameters.</p>
On proportional distributing financial capacity in children alimony in complex families
Get PDFVanuit een rekenkundige benadering analyserenauteurs de jurisprudentie rond kinderalimentatiebij samengestelde gezinnen, met name de fase vandraagkrachtverdeling en draagkrachtvergelijking.Zij constateren inconsistenties in rekenmethodenzoals gehanteerd in de lagere jurisprudentie en in-terferentie met uitspraken van de HR. Zij ontwik-kelen een rekenmethode die deze problemen (gro-tendeels) wegneemt. Deze methode kan in een appworden geïmplementeerd, waardoor alle betrokkenpartijen snel inzicht kunnen krijgen in de uiteinde-lijke draagkrachtverdeling.<br/
Queues with Congestion-dependent Feedback
Get PDFThis dissertation expands the theory of feedback queueing systems and applies a number of these models to a performance analysis of the Transmission Control Protocol, a flow control protocol commonly used in the Internet
On proportional distributing financial capacity in children alimony in complex families
Get PDFVanuit een rekenkundige benadering analyserenauteurs de jurisprudentie rond kinderalimentatiebij samengestelde gezinnen, met name de fase vandraagkrachtverdeling en draagkrachtvergelijking.Zij constateren inconsistenties in rekenmethodenzoals gehanteerd in de lagere jurisprudentie en in-terferentie met uitspraken van de HR. Zij ontwik-kelen een rekenmethode die deze problemen (gro-tendeels) wegneemt. Deze methode kan in een appworden geïmplementeerd, waardoor alle betrokkenpartijen snel inzicht kunnen krijgen in de uiteinde-lijke draagkrachtverdeling.<br/
Cross docking for libraries with a depot
Get PDFLibrary organizations in the Netherlands show an increasing interest to employ depots for low-cost storage and demand fulfillment of item requests. Typically, all libraries in an organization have a shared catalog, and, on local unavailability, requests can be shipped from elsewhere in the organization. The depot can be used to consolidate shipment requests by making tours along all libraries, delivering requested items, but also picking up items that have to be stored at the depot, or that have to be shipped from one library to another. Cross docking and delayed shipments are two preferred methods for fulfilling requests that cannot be directly met using on-hand stock at the depot. In this paper, we compare these two methods from an inventory control perspective. We model the library system as a Markov Decision process. For one- and two-location systems, we derive analytical results for the average-cost optimal policy, showing that the decision to store items from the location at the depot satisfies a threshold structure depending on the number of rented items. For larger instances, an effective heuristic is proposed exploiting this threshold structure. In numerical experiments, important managerial insights are obtained by comparing cross docking and delayed shipments in different situations. Cross docking is shown to add most value in systems with low total stock, however, delayed shipments may achieve similar costs as cross docking when stock is high or when tours frequently visit all locations. Furthermore, effective decisions can be based on simple model formulations with memoryless rental time distributions
On proportional distributing financial capacity in children alimony in complex families
Get PDFVanuit een rekenkundige benadering analyserenauteurs de jurisprudentie rond kinderalimentatiebij samengestelde gezinnen, met name de fase vandraagkrachtverdeling en draagkrachtvergelijking.Zij constateren inconsistenties in rekenmethodenzoals gehanteerd in de lagere jurisprudentie en in-terferentie met uitspraken van de HR. Zij ontwik-kelen een rekenmethode die deze problemen (gro-tendeels) wegneemt. Deze methode kan in een appworden geïmplementeerd, waardoor alle betrokkenpartijen snel inzicht kunnen krijgen in de uiteinde-lijke draagkrachtverdeling.<br/
Corrigendum to “Representations for the extreme zeros of orthogonal polynomials” [J. Comput. Appl. Math. 233 (2009) 847–851]
Get PDFWe correct representations for the endpoints of the true interval of orthogonality of a sequence of orthogonal polynomials that were stated by us in the Journal of Computational and Applied Mathematics 233 (2009) 847–851
Continuous feedback fluid queues.
Get PDFABSTRACT We investigate a fluid buffer which is modulated by a stochastic background process, while the momentary behavior of the background process depends on the current buffer level in a continuous way. Loosely speaking the feedback is such that the background process behaves 'as a continuous-time Markov chain' with generator Q(y) at times when the buffer level is y, where the entries of Q(y) are continuous functions of y. Moreover, the fluid-flow rates for the buffer may also depend continuously on the current buffer level. First we define the feedback behavior precisely. Then we deduce the Kolmogorov forward equations for the joint background/buffer-process under some regularity assumptions. After presenting the differential equations and boundary conditions for the stationary distributions, we find an explicit solution when the background process has two states. 2000 Mathematics Subject Classification: 60K25 Keywords and Phrases: Fluid queue, feedback, forward equation
A versatile model for asymmetric TCP sources
Get PDFIn the literature it is quite common to model TCP sources as Additive-Increase Multiplicative-Decrease sources. Within this framework we develop a Markov chain model that captures the interaction between the source and buffer processes. This approach permits to investigate a number of TCP related phenomena that are inherently stochastic. In the first place we evaluate two popular loss models: one in which sources react in a synchronized manner to loss, the other in which just one source reduces its window after loss epochs with a probability that is proportional to the source window. A comparison with a simulation in ns2 shows that the real loss process is somewhere in between the two loss models. Secondly, we show that the celebrated 'root p' law is still valid when the loss process is strictly dependent on the source state instead of an autonomous process, and the roundtrip times are stochastic instead of constant. Finally, we analyze the impact of source on/off behavior when the source on-times depend on momentary source transmission rates, as is the case in practice
