Process redesign for effective use of product quality information in meat chains

To fulfil segmented consumer demand and add value, meat processors seek to exploit quality differences in meat products. Availability of product quality information is of key importance for this. We present a case study where an innovative sensor technology that provides estimates of an important meat quality feature is considered. Process design scenarios that differ with respect to sorting complexity, available product quality information, and use of temporary buffers are assessed using a discrete event simulation model. Results indicate that increasing sorting complexity by use of advanced product quality information results in a reduction of processing efficiency. Use of production buffers was found to increase processing flexibility and mitigate negative effects of high sorting complexity. This research illustrates how the use of advanced product quality information in logistics’ decision-making affects sorting performance, processing efficiency, and the optimal processing design, an area that has so far received little attention in literature

Effective sourcing strategies for perishable product supply chains

Purpose – The purpose of this paper is to assess whether an existing sourcing strategy can effectively supply products of appropriate quality with acceptable levels of product waste if applied to an international perishable product supply chain. The authors also analyse whether the effectiveness of this sourcing strategy can be improved by including costs for expected shelf life losses while generating order policies. Design/methodology/approach – The performance of sourcing strategies is examined in a prototype international strawberry supply chain. Appropriate order policies were determined using parameters both with and without costs for expected shelf life losses. Shelf life losses during transport and storage were predicted using microbiological growth models. The performance of the resulting policies was assessed using a hybrid discrete event chain simulation model that includes continuous quality decay. Findings – The study's findings reveal that the order policies obtained with standard cost parameters result in poor product quality and large amounts of product waste. Also, including costs for expected shelf life losses in sourcing strategies significantly reduces product waste and improves product quality, although transportation costs rise. Practical implications – The study shows that in perishable product supply chain design a trade-off should be made between transportation costs, shortage costs, inventory costs, product waste, and expected shelf life losses. Originality/value – By presenting a generically applicable methodology for perishable product supply chain design, the authors contribute to research and practice efforts to reduce food waste. Furthermore, product quality information is included in supply chain network design, a research area that is still in its infancy

Efficient and accurate calculation of exact exchange and RPA correlation energies in the Adiabatic-Connection Fluctuation-Dissipation theory

Recently there has been a renewed interest in the calculation of exact-exchange and RPA correlation energies for realistic systems. These quantities are main ingredients of the so-called EXX/RPA+ scheme which has been shown to be a promising alternative approach to the standard LDA/GGA DFT for weakly bound systems where LDA and GGA perform poorly. In this paper, we present an efficient approach to compute the RPA correlation energy in the framework of the Adiabatic-Connection Fluctuation-Dissipation formalism. The method is based on the calculation of a relatively small number of eigenmodes of RPA dielectric matrix, efficiently computed by iterative density response calculations in the framework of Density Functional Perturbation Theory. We will also discuss a careful treatment of the integrable divergence in the exact-exchange energy calculation which alleviates the problem of its slow convergence with respect to Brillouin zone sampling. As an illustration of the method, we show the results of applications to bulk Si, Be dimer and atomic systems.Comment: 12 pages, 6 figures. To appear in Phys. Rev.

A comparative study of numerical methods for the overlap Dirac operator--a status report

Improvements of various methods to compute the sign function of the hermitian Wilson-Dirac matrix within the overlap operator are presented. An optimal partial fraction expansion (PFE) based on a theorem of Zolotarev is given. Benchmarks show that this PFE together with removal of converged systems within a multi-shift CG appears to approximate the sign function times a vector most efficiently. A posteriori error bounds are given.Comment: 3 pages, poster contribution to Lattice2001(algorithms

Het kan dus nog met bestuurskunde!?

Lenny van Klink (22) heeft destijds bestuurskunde gekozen omdat hij net als zovele onder ons graag iets met leiding geven wilde doen en tegelijk iets breeds. De keus is dan beperkt in de universitaire wereld: bedrijfskunde of bestuurskunde. Het idee om te leren hoe je het best gele, plastic emmertjes moet verkopen trok hem niet, dus werd het bestuurskunde. Na succesvol drie jaar van de studie te hebben doorlopen en daarnaast een penningmeesterschap van de B.I.L. heeft hij een stage bij subsidie-adviesburo PNO, Pecunia Non Olet (geld stinkt niet), achter de rug

Testament van een eerstejaars: Leiden, 3 september 1990

Na 22 jaren in het leven maak ik het testament op van mijn jeugd, niet dat ik geld of goed heb weg te geven, voor slimme jongen heb ik nooit gedeugd. Toch heb ik nog wat mooie idealen goed van snit, hoewel ze uit de mode zijn, wie ze hebben wil die kan ze komen halen, vooral jonge mensen vinden ze nog fijn ..

Towards a Diagnostic Instrument to Identify Improvement Opportunities for Quality Controlled Logistics in Agrifood Supply Chain Networks

 Western-European consumers have become not only more demanding on product availability in retail outlets but also on other food attributes such as quality, integrity, and safety. When (re)designing food supply-chain networks, from a logistics point of view, one has to consider these demands next to traditional efficiency and responsiveness requirements. The concept ‘quality controlled logistics’ (QCL) hypothesizes that if product quality in each step of the supply chain can be predicted in advance, goods flows can be controlled in a pro-active manner and better chain designs can be established resulting in higher product availability, constant quality, and less product losses. The paper discusses opportunities of using real-time product quality information for improvement of the design and management of ‘AgriFood Supply Chain Networks’, and presents a preliminary diagnostic instrument for assessment of ‘critical quality’ and ‘logistics control’ points in the supply chain network. Results of a tomato-chain case illustrate the added value of the QCL concept for identifying improvement opportunities in the supply chain as to increase both product availability and quality. Future research aims for the further development of the diagnostic instrument and the quantification of costs and benefits of QCL scenarios

Voorwoord

Nieuwe handen komen uit de mouw. Frisse koppen hebben deze BB gevuld en vormgegeven. Het oude team is na de laatste net niet weer gehaalde deadline zuchtend, steunend en kreunend met de VUT gegaan

Voorwoord

Met blijdschap en vreugde kondigen wij U aan dat, na een zware bevalling, tot de hoofdredactie is toegetreden: Karin Rosa Huiberts. De gehele redactie zit momenteel met een postnatale depressie. Bloemen zijn altijd welkom. Ook inspiratie, irritatie en eigen creaturen worden altijd gewaardeerd

Algemene Leden Vergadering

Een donker achterkamertje ergens in Leiden. Kaarslicht. Zenuwachtige blikken verraden op handen zijnde veranderingen. Onheilspellend gefluister. Plots een luide slag: "Hierbij open ik de jaarlijkse Algemene Leden Vergadering van de Bestuurskundige Interfacultaire vereniging Leiden.&quot