Werner Jammernegg

Analysing the impact of disruptions in intermodal transport networks: A micro simulation-based model

Transport networks have to provide carriers with time-efficient alternative routes in case of disruptions. It is, therefore, essential for transport network planners and operators to identify sections within the network which, if broken, have a considerable negative impact on the networks performance. Research on transport network analysis provides lots of different approaches and models in order to identify such critical sections. Most of them, however, are only applicable to mono-modal transport networks and calculate indices which represent the criticality of sections by using aggregated data. The model presented, in contrast, focuses on the analysis of intermodal transport networks by using a traffic micro simulation. Based on available, real-life data, our approach models a transport network as well as its actual traffic participants and their individual decisions in case of a disruption. The resulting transport delay time due to a specific disruption helps to identify critical sections and critical networks, as a whole. Therefore, the results are a valuable decision support for transport network planners and operators in order to make the infrastructure less vulnerable, more attractive for carriers and thus more economically sustainable. In order to show the applicability of the model we analyse the Austrian intermodal transport network and show how critical sections can be evaluated by this approach.

Dynamic, customer-oriented improvement of supply networks

The paper considers the dynamic coordination of a supply network consisting of one supplier company and multiple customer companies. The ongoing business relationships are based on general contracts. But also the informal understandings and agreements that are facilitated by ongoing business relationships are taken into account: the supplier tries to reduce the prevailing information asymmetry by performing regular customer satisfaction surveys. This information together with the contract attributes is used by the supplier to improve the performance of its business processes and/or the contract attributes that contribute the most to improving total customer satisfaction. We propose a four-stage decision-making procedure which is mainly based on statistical analyses (dependency analysis, logit model) and a managerial procedure describing whether the supplier should renegotiate the contract with a specific customer to improve the performance of the overall network. The statistical analysis is illustrated by a real-world case study of a medium-sized German company and its customers.

A Framework for Economic and Environmental Sustainability and Resilience of Supply Chains

Traditionally supply chain management decisions are based on the economic performance which is expressed by financial and non-financial measures, i.e. costs and customer service. From this perspective, in the last decades, several logistics trends, i.e. outsourcing, offshoring and centralization, emerged. Recently, studies have shown that the focus on the cost aspect is no longer sufficient. Due to internal and external drivers (e.g. customer pressure, regulations, etc.) environmental criteria become more and more important for the decision-making of individual enterprises. Furthermore, the risk which is related to the increased transportation distances resulting from these strategies is often not taken into account or underestimated. These shifts in priorities of companies force them to search for new logistics strategies that are at the same time cost-efficient, environmentally friendly and reliable. Based on this integrated perspective new logistics trends, like on- and nearshoring, flexible supply base or flexible transportation, have come up recently and will gain more importance in the near future. Relying on a flexible supply base a company can benefit from low costs in an offshore facility and simultaneously be able to respond quickly to demand fluctuations and react to delivery delays and disruptions by serving the market also from an onshore site. A single-period dual sourcing model is presented to show the effects of emission costs on the offshore, onshore and total order quantity.

Newsvendor Problems with VaR and CVaR Consideration

In this chapter, we consider approaches to express the risk preferences of a newsvendor by means of the risk measures value at risk (VaR), conditional value at risk (CVaR), and the mean-CVaR rule, which usually is defined as a convex combination of expected profit and CVaR. With these risk measures the decision maker can exploit risk-averse or risk-neutral behavior. In addition, we introduce a more general mean-CVaR measure where also risk- taking behavior can be expressed. The overall goal of the paper is a comparative analysis of these risk measures in the newsvendor framework. On the one hand VaR, CVaR and the (general) mean-CVaR, measures are used as objective functions to derive the respective optimal order quantity. Extensions of the basic models are reviewed. On the other hand the risk measures, especially VaR, are constraints of the model. We first review models with the expected profit as objective. Then the general mean-CVaR measure is taken as objective function and a service constraint and a loss constraint are added. In this framework, the risk attitudes of the newsvendor can be deduced from the characteristics of a product together with the specified service target and loss target.

Gestaltung von reaktionsschnellen Produktionsnetzwerken

Durch die Konzentration auf die eigenen Kernkompetenzen sind viele Industrieunternehmen in den meisten Branchen in ein Netzwerk von Produktions- und Zulieferunternehmen eingebettet, da Teile des Auftragsabwicklungsprozesses ausgelagert sind. Die Wahl der Outsourcingpartner war historisch meist durch das Kostenkriterium dominiert. Aufgrund des in vielen Branchen zu beobachtenden Trends zur Kundenauftragsproduktion geben viele Manager unterschiedlicher Branchen an, das Qualitats-, Service- und Flexibilitatskriterien fur die Lieferantenauswahl immer wichtiger werden. Diese Tendenz wird allerdings durch empirische Untersuchungen nicht bestatigt. Die tatsachliche Gestalt der Liefervertrage vieler Unternehmen ist durch Kurzfristigkeit gekennzeichnet, wobei oft die Produktqualitat das Qualifikationskriterium und der Produktpreis das eigentliche Auswahlkriterium eines Lieferanten darstellen (vgl. Cohen u. Agrawal 1999).

Bewertung unterschiedlicher Beschaffungsstrategien für Risk-Hedging Supply Chains unter Berücksichtigung intermodaler Transportprozesse

In der vorliegenden Arbeit wird anhand einer realen Supply Chain der chemischen Industrie ein Vorgangsmodell fur die Leistungsbewertung von Risk-Hedging Supply Chains (hohes Beschaffungsrisiko, geringes Nachfragerisiko) in einem dynamischen Umfeld vorgestellt. Insbesondere warden so genannte Portfolio-Beschaffungsstrategien entwickelt, die sich aus kurz- und langfristigen Vertragen zusammensetzen. Weitere analysierte Beschaffungsstrategien berucksichtigen Spekulationslager und die Auswirkungen unterschiedlicher Transportmittel (intermodaler Transport) zur Absicherung gegenuber der Volatilitat des Rohmaterialpreises. Die Simulationsergebnisse zeigen, dass die gesamten Beschaffungskosten durch die alternativen Beschaffungsstrategien und Transportmittel durchschnittlich um bis zu 12% im Vergleich zu einer „reinen“ Beschaffungsstrategie, ohne die Nutzung eines Spekulationslager und ohne den Einsatz eines alternativen (langsameren) Transportmittels mit hoherer Ladekapazitat, gesenkt werden konnen. Abschliesend werden Handlungsrichtlinien fur das Supply Chain Management fur die Auswahl einer effizienten Beschaffungsstrategie und eines passenden Transportmittels vorgestellt.

Regelkreis zur Bestimmung kundenorientierter Innovationen

Kundenorientierung und Prozessorientierung sind fur viele Organisationen sowohl im Fertigungsbereich als auch im Dienstleistungs-und Non-Profitsektor aktuelle Leitlinien fur ein erfolgreiches Management. Die stei-gende Bedeutung der Kundenorientierung ist aus unternehmensexterner Sicht in vielen Branchen im zunehmenden Wandel von Verkaufermarkten zu Kaufermarkten begrundet. Unternehmensintern fuhrt dies zur groseren Beachtung von organisatorischen Querschnittsfunktionen wie Qualitat und Logistik. Fur viele Unternehmen ist dies der auslosende Faktor, zumindest formell eine Prozessorganisation einzufuhren.

Optimal decisions for an insurance contract with experience rating

In this paper we consider the insurance of assets with experience rating in the framework of a discrete-time dynamic decision model. The goal of the risk-averse agent (insurance buyer) is to maximize the expected utility of wealth at the finite planning horizon. First, it has to be decided whether a contract should be bought or not. The contract gives the possibility to choose in each period between three alternatives: to buy insurance and to file a claim, to buy insurance and not to file a claim, to suspend insurance. For this case structural properties of the optimal strategy are obtained by means of dynamic programming. Especially, we present a condition for the experience rating scheme such that the decision to suspend insurance is irreversible during the planning period (stopping rule). In the final section we present some numerical experiences. Among others it will be shown that the optimal decision functions generally are not monotone with respect to the agents claim history.

Dependency Between Performance of Production Processes and Variability - an Analysis Based on Empirical Data

It is commonly accepted that variability is one of the main challenges in designing and managing manufacturing processes. Many process improvement concepts that focus primarily on communication and information exchange, flow time reduction, etc., finally influence variability. In particular, they reduce variability or mitigate the operational effects of variability. Vendor managed inventory or collaborative planning, forecasting, and replenishment are just two examples of such concepts. The effect on selected performance measures is mostly shown by idealized quantitative models, but there are only few results from real-world processes. In our study we want to illustrate and quantify the impact of variability on the performance of production processes by means of two real manufacturing processes. Case process one is an assembly process of frequency inverters and case process two is the assembly process of sliding glass top systems. For the inverter assembly process we want to show the operational impact of reduced demand variability (reduced forecast error), achieved by implementing Vendor managed inventory as well as collaborative planning. In the glass top assembly process internal variability is addressed by assessing the impact of the production lot size. Both processes are mainly evaluated by using WIP and flow time as key performance measures. The analysis is conducted with rapid modeling software based on open queuing networks. Our results show that a reasonable decrease in inventory and flow time can be achieved without any decline of customer service.

Single Period Combined Inventory and Pricing Models

We consider a single product, single period inventory problem with stochastic price-dependent demand. The ordering and pricing decision has to be made at the beginning of the period before demand is realized. Unsatisfied demand is lost and excess inventory has to be salvaged. This problem is known in literature as the price-setting newsvendor model.