09261 Abstracts Collection -- Models and Algorithms for Optimization in Logistics

From June 21 to June 26, 2009 the Dagstuhl Seminar Perspectives Workshop 09261 ``Models and Algorithms for Optimization in Logistics \u27\u27 was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

A Branch-and-Price Algorithm for Optimal Routing of Delivery Robots

Increasing parcel volumes, environmental challenges, and customer expectations have made innovative delivery concepts for last-mile logistics essential in recent years. Autonomous delivery vehicles such as delivery robots or drones are tested worldwide. In this work, we examine the use of electrical delivery robots to optimize a last-mile network. The network consists of a fleet of homogeneous single-unit capacity robots, depots equipped with recharging stations, and customers. Each customers is defined by a time window and a profit. The goal is to find a set of tours that maximizes the total collected profit. These tours have to respect the customers' time windows and battery constraints of the robots. We present a branch-and-price algorithm to solve this combinatorial optimization problem exactly. Within this algorithm, the problem of finding feasible tours arises. To decide on the feasibility of a tour, we present a polynomial dynamic program and prove its correctness. The computational studies on modified benchmark instances show that the algorithm can solve instances that have realistic time window lengths and up to 144 customers in a reasonable time

Hands-on Testing of Last Mile Concepts

AbstractSince 1995 the freight transport performance within Europe has increased annually by 1.2% and is expected to grow further over the coming decades. Being the sources and sinks of transport activities, Europe's cities are strongly affected by the resulting undesirable effects of transportation. This applies in particular to North West Europe (NWE), one of the most urban regions in Europe. NWE therefore stands in urgent need of solutions for efficient urban freight logistics.Focusing on the last mile of freight deliveries the INTERREG IVB NWE project LaMiLo (Last Mile Logistics) addressed this issue. The project promoted Urban Consolidation Centres (UCCs) as they allow and encourage transport consolidation as well as modal shift. Decoupling the last mile at the city borders, large vehicles are used for bundled, long haul transports outside the city whilst sustainable transport means are used inside.In the knowledge that UCC attempts with huge government subsidies have been made several times before but rarely succeeded, the core of the LaMiLo project was to enable environment for UCC operations that accomplish a sustainable last mile and can as well be transformed in successful business models. Thereto, UCC concepts were operationalised and implemented in a number of pilots in metropolitan areas and cities all around NWE:•Paris: A UCC was field-tested to which freight was brought by truck and afterwards delivered by cargo bikes.•Netherlands: Central hubs were put into operation to streamline the home delivery of parcels. Thereto, a Freight Circle service was launched in the cities of Nijmegen and Maastricht which used e-bikes and enabled customer-specific delivery times.•London: A UCC was set up to bundle goods for the public sector which were destined for the boroughs of Camden and its partners Enfield and Waltham.•Brussels: A UCC was launched at the Port of Brussels offering warehouse services and deliveries to retailers in the city.The key results gained from the studies primarily include the demonstration of UCCs as possible last mile solutions. Beyond their economic performance, their environmental effects as well as their social impacts were evaluated. Exemplary results include that all the pilots contributed towards emission reduction and total distance travelled through city centres and residential areas. Gained best practice and lessons learnt about the examined UCC concepts were discussed and shared at transnational level to encourage relating solutions for further cities

Zur Nutzung des Bilanzanalyse-Systems MIDIAS im Branchenvergleich: Eine Dokumentation am Beispiel der Bekleidungsindustrie

Im Rahmen eines Praktikums zur computergestützten Unternehmensanalyse wurden im Sommersemester 1990 am Lehrstuhl für Organisation mit Hilfe des Datev-Proprammes MIDIAS die Jahresabschlüsse von 18 Unternehmen der Bekleidungsindustrie untersucht. Ziel dieser Analyse war es, anhand von Einzelanalysen Kennzahlen abzuleiten, die über die gesamte Unternehmensstichprobe in der Lage waren, erfolgreiche Unternehmen von weniger erfolgreichen signifikant zu unterscheiden. Die Untersuchung wurde bewußt auf die Unternehmen einer Branche beschränkt, um auch die häufig vernachlässigten Kennzahlen der güter- und leistungswirtschaftlichen, operativen Unternehmensbereiche in das Analysedesign aufnehmen zu können. Die Erkenntnisse aus der Einzelbetrachtung der Jahresabschlüsse wurden dann in einem zweiten Schritt durch statistische Kennzahlenauswertungen über die gesamte Stichprobe geprüft

Generisches Simulationsmodell für Stückgutspeditionsanlagen auf Basis der Anforderungen von KMUs

Simulation can be used to plan and optimize less-than-truckload (LTL) terminals. To develop simulation models, specific expertise in this field is needed, which often requires high financial investments for acquisition of this knowledge. Due to limited financial resources, SMEs are often incapable to get to this expertise. The objective of the paper is to develop a generic model for LTL terminal planning that can be used without simulation expertise and that can be adapted to individual SME layouts. Therefore, based on focus group interviews with SMEs, a catalog of requirements is developed, including input variables and design criteria. Key performance indicators (KPIs) are defined to evaluate the results. A feasibility study for implementing a generic model based on the identified requirements is then performed. The implementation is done by modeling the I-layout of an LTL terminal

Index-Based Pricing Models in Strategic Freight Procurement

This extended abstract addresses index-based pricing models between shippers and carriers in strategic freight procurement. The increasingly unpredictable transportation cost developments, caused by a variety of different international crises, led to the need for shippers and carriers to find an equitable form of collaboration. Index-based pricing models are one way to regulate the price adjustment between shipper and carrier during the contract period due to cost developments. However, one obstacle to agreeing on such models is to find the correct index for the respective cost component that is adequate for both shipper and carrier and reflects the actual cost development of the carrier. In semi-structured expert interviews, we investigated which strategies are used to reflect volatile cost developments, how index-based pricing models work, and where problems are seen in this context. Furthermore, a broader study can lead to confirmation or further classification of the results. The abstract describes index-based pricing models with focus on road freight, but the mechanism will work for other transportation modes as well

Glutaconate CoA-transferase from Acidaminococcus fermentans: the crystal structure reveals homology with other CoA-transferases

AbstractBackground: Coenzyme A-transferases are a family of enzymes with a diverse substrate specificity and subunit composition. Members of this group of enzymes are found in anaerobic fermenting bacteria, aerobic bacteria and in the mitochondria of humans and other mammals, but so far none have been crystallized. A defect in the human gene encoding succinyl-CoA: 3-oxoacid CoA-transferase causes a metabolic disease which leads to severe ketoacidosis, thus reflecting the importance of this family of enzymes. All CoA-transferases share a common mechanism in which the CoA moiety is transferred from a donor (e.g. acetyl CoA) to an acceptor, (R)-2-hydroxyglutarate, whereby acetate is formed. The transfer has been described by a ping-pong mechanism in which CoA is bound to the active-site residue of the enzyme as a covalent thiol ester intermediate. We describe here the crystal structure of glutaconate CoA-transferase (GCT) from the strictly anaerobic bacterium Acidaminococcus fermentans. This enzyme activates (R)-2-hydroxyglutarate to (R)-2-hydroxyglutaryl-CoA in the pathway of glutamate fermentation. We initiated this project to gain further insight into the function of this enzyme and the structural basis for the characteristics of CoA-transferases.Results: The crystal structure of GCT was solved by multiple isomorphous replacement to 2.55 Å resolution. The enzyme is a heterooctamer and its overall arrangement of subunits can be regarded as an (AB)4tetramer obeying 222 symmetry. Both subunits A and B belong to the open α/β-protein class and can be described as a four-layered α/α/β/α type with a novel composition and connectivity of the secondary structure elements. The core of subunit A consists of seven α/β repeats resulting in an all parallel central β sheet, against which helices pack from both sides. In contrast, the centre of subunit B is formed by a ninefold mixed β sheet. Inboth subunits the helical C terminus is folded back onto the N-terminal domain to form the third layer of helices.Conclusions: The active site of GCT is located at the interface of subunits A and B and is formed by loops of both subunits. The funnel-shaped opening to the active site has a depth and diameter of about 20 Å with the catalytic residue, Glu54 of subunit B, at the bottom. The active-site glutamate residue is stabilized by hydrogen bonds. Despite very low amino acid sequence similarity, subunits A and B reveal a similar overall fold. Large parts of their structures can be spatially superimposed, suggesting that both subunits have evolved from a common ancestor

Partitioned vs. Integrated Planning of Hinterland Networks for LCL Transportation

Utilizing existing transportation networks better and designing (parts of) networks involves routing decisions to minimize transportation costs and maximize consolidation effects. We study the concrete example of hinterland networks for the truck-transportation of less-than-container-load (LCL) ocean freight shipments: A set of LCL shipments is given. They have to be routed through the hinterland network to be transported to an origin port and finally to the destination port via ship. On their way, they can be consolidated in hubs to full-container-load (FCL) shipments. The overall transportation cost depends on the selection of the origin port and the routing and consolidation in the hinterland network. A problem of this type appears for the global logistics provider DB Schenker. We translate the business problem into a hub location problem, describe it mathematically, and discuss solution strategies. As a result, an integrated modeling approach has several advantages over solving a simplified version of the problem, although it requires more computational effort