The KLU faculty, post-docs, and PhD candidates regularly publish the results of their research in scientific journals. You will find a complete overview of all KLU publications below (e.g. articles in peer-reviewed journals, professional journals, books, working papers, and conference proceedings). Search for relevant terms and keywords, or filter the list by name, year of publication or type of publication. The references include DOIs and abstracts where available, and you can download them to your own reference database or platform. We regularly update the database with new publications.

Journal Articles (Peer-Reviewed)

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Abstract: The repeated execution of workflow logic is usually modeled with loop constructs in the workflow model. But there are cases where it is not known at design time that a subset of activities has to be rerun during workflow execution. For instance in e-Science, scientists might have to spontaneously repeat a part of an experiment modeled and executed as workflow in order to gain meaningful results. In general, a manually triggered ad hoc rerun enables users reacting to unforeseen problems and thus improves workflow robustness. It allows natural scientists steering the convergence of scientific results, business analysts controlling their analyses results, and it facilitates an explorative workflow development as required in scientific workflows. In this paper, two operations are formalized for a manually enforced repeated enactment of activities, the iteration and the re-execution. The focus thereby lies on an arbitrary, user-selected activity as a starting point of the rerun. Important topics discussed in this context are handling of data, rerun of activities in activity sequences as well as in parallel and alternative branches, implications on the communication with partners/services and the application of the concept to workflow languages with hierarchically nested activities. Since the operations are defined on a meta-model level, they can be implemented for different workflow languages and engines.

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Copy reference link   DOI: 10.1007/s00187-012-0157-8

Abstract: Cost reduction is usually confronted with conflicts and resistance. Besides planning and controlling measures the management accounting literature discusses behavioral and organizational factors (e.g., top management commitment, participation, cost culture) in order to overcome this resistance. Thus, from a theoretical perspective different concepts exist for implementing an effective long-term cost reduction. However, only little empirical research can be found that investigates the relative importance of “soft” behavioral and implementation factors compared to general planning and control measures. This study examines the role of behavioral and organizational (“soft”) factors in comparison to planning and control (“hard”) factors in cost reduction projects. Target costing or activity-based costing projects represent examples for strategic cost reduction projects which are considered in this study. The sample comprises 131 chief management accountants of medium-size and large German companies which were involved in such strategic cost reduction projects. Structural equation modeling is used for deriving the results. The results show that cost culture, top management commitment, and participation are of particular importance for the success of cost reductions. Their influence drives significantly planning and controlling measures which in turn determine the effectiveness of cost reduction measures.

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Abstract: The performance of business processes is measured and monitored in terms of Key Performance Indicators (KPIs). If the monitoring results show that the KPI targets are violated, the underlying reasons have to be identified and the process should be adapted accordingly to address the violations. In this paper we propose an integrated monitoring, prediction and adaptation approach for preventing KPI violations of business process instances. KPIs are monitored continuously while the process is executed. Additionally, based on KPI measurements of historical process instances we use decision tree learning to construct classification models which are then used to predict the KPI value of an instance while it is still running. If a KPI violation is predicted, we identify adaptation requirements and adaptation strategies in order to prevent the violation.

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Copy reference link   DOI: 10.15358/0344-1369-2012-2-140

Abstract: Brand extension and co-branding are two brand strategies with numerous similarities, but also distinct differences. So far, the existing literature has analyzed these strategies without making a detailed comparison between them. That is why this study discusses the joint and differing opportunities and risks of these two strategies. Spill-over effects, cost synergies, image transfers, coordination and independence issues are assessed in detail. In addition, the study considers the critical success factors for each strategy, which is necessary for a final assessment of the different strategy benefits. These success factors include characteristics of the parent brand, product and brand fit as well as consumer and company characteristics. In this context, the study elaborates under which general conditions which strategy may be more preferable. In the end, it becomes clear that there are some advantages related to a co-branding strategy, which cannot be realized by pursuing a brand extension strategy.

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Copy reference link   DOI: 10.1007/s11761-011-0095-6

Abstract: Service composition is a well-established field of research in the service community. Services are commonly regarded as black boxes with well-defined interfaces that can be recursively aggregated into new services. The black-box nature of services does not only include the service implementation but also implies the use of middleware and hardware to run the services. Thus, service composition techniques are typically limited to choosing between a set of available services. In this paper, we keep the black-box nature and the principle of information hiding of services, but in addition we break up services vertically. By introducing vertical service composition, we allow services to be provisioned on demand using the middleware and runtime environment that specifically meets user-required quality of services. Therefore, a service is setup individually for services requestors instead of providing them with a pre-determined list of available services to choose from. We introduce the concept of vertical service composition and present an extension to an enterprise service bus that implements the concept of vertical service composition by combining concepts from provisioning with those of (dynamic) service binding.

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Copy reference link   DOI: 10.1016/j.socscimed.2011.02.011

Abstract: In an effort to improve operational efficiency, healthcare services around the world have adopted process improvement methodologies from the manufacturing sector, such as Lean Production. In this paper we report on four multi-level case studies of the implementation of Lean in the English NHS. Our results show that this generally involves the application of specific Lean ‘tools’, such as ‘kaizen blitz’ and ‘rapid improvement events’, which tend to produce small-scale and localised productivity gains. Although this suggests that Lean might not currently deliver the efficiency improvements desired in policy, the evolution of Lean in the manufacturing sector also reveals this initial focus on the ‘tool level’. In moving to a more system-wide approach, however, we identify significant contextual differences between healthcare and manufacturing that result in two critical breaches of the assumptions behind Lean. First, the customer and commissioner in the private sector are the one and the same, which is essential in determining ‘customer value’ that drives process improvement activities. Second, healthcare is predominantly designed to be capacity-led, and hence there is limited ability to influence demand or make full use of freed-up resources. What is different about this research is that these breaches can be regarded as not being primarily ‘professional’ in origin but actually more ‘organisational’ and ‘managerial’ and, if not addressed could severely constrain Lean’s impact on healthcare productivity at the systems level.

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Copy reference link   DOI: 10.1057/jibs.2012.15

Abstract: We argue that leader-directed voice (i.e., communicating critical suggestions for change to the leader) is a relational phenomenon, and that it is affected by an inherent feature of multinational teams: members’ (dis)similarities in nationality. We tested our hypotheses in a sample of middle managers who were working in multinational teams. The results of this study show that leaders of multinational teams are more likely to profit from the local know-how of employees from underrepresented nationalities when they are open to their ideas, and when they have the same nationality. The study also shows that the effects of being open to employees’ ideas and sharing the same nationality are mediated by affective commitment and psychological safety, respectively. We discuss how, even though the current relational demography perspective with its dichotomous understanding of (dis)similarity is not suited to capture the dynamics of cultural differences, it does set the stage for future studies to examine the cultural dynamics behind an individual's experience of being different from other team members in multinational teams. We also discuss the practical implications of these findings for multinational companies.

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Copy reference link   DOI: 10.1016/j.jocrd.2012.07.001

Abstract: Online surveys are gaining increasing momentum in clinical research. Ease of recruitment and low cost are two of the biggest advantages of Internet studies. There are, however, concerns about their reliability and validity.The present study compared the psychometric properties of self-report instruments measuring obsessive-compulsive disorder (OCD) across three samples: (1) participants with a confirmed diagnosis of OCD (n=66), (2) participants with a probable diagnosis of OCD (n=86) and (3) clinical experts on OCD and students who were asked to pretend to have OCD (n=121). Psychometric indices of the Yale-Brown Obsessive Compulsive Score (Y-BOCS) and the Obsessive Compulsive Inventory (OCI-R) served as indicators for reliability and validity.Both patient samples revealed good retest reliability scores and good correlations between Y-BOCS and OCI-R scores. In contrast, the expert group showed poor retest reliabilities and mixed results for the intercorrelations between OCI-R and Y-BOCS scores. Simulators display a marked tendency to over-report symptoms on the OCI-R.Good psychometric properties of online studies may serve as a proxy for the validity of diagnoses.

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Copy reference link   DOI: 10.1007/s10551-011-0997-4

Abstract: In this article, we hypothesize that leaders who display group-oriented values (i.e., values that focus on the welfare of the group rather than on the self-interest of the leader) will be evaluated more positively by their followers than leaders who do not display group-oriented values. Importantly, we expected these effects to be more pronounced for leaders who are ingroup members (i.e., stemming from the same social group as their followers) than for leaders who are outgroup members (i.e., leaders stemming from a different social group than their followers). We tested our hypotheses in two studies. Results of a field study (N = 95) showed the expected relationship between leaders’ group-oriented values and followers’ identification with their leaders. A scenario study (N = 137) replicated the results and extended it to followers’ endorsement of their leaders. Overall, these findings suggest that displaying group-oriented values pays off more for ingroup than for outgroup leaders.

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Copy reference link   DOI: 10.1016/j.ejor.2011.09.028

Abstract: One of the latest developments in network revenue management (RM) is the incorporation of customer purchase behavior via discrete choice models. Many authors presented control policies for the booking process that are expressed in terms of which combination of products to offer at a given point in time and given resource inventories. However, in many implemented RM systems—most notably in the hotel industry—bid price control is being used, and this entails the problem that the recommended combination of products as identified by these policies might not be representable through bid price control. If demand were independent from available product alternatives, an optimal choice of bid prices is to use the marginal value of capacity for each resource in the network. But under dependent demand, this is not necessarily the case. In fact, it seems that these bid prices are typically not restrictive enough and result in buy-down effects.We propose (1) a simple and fast heuristic that iteratively improves on an initial guess for the bid price vector; this first guess could be, for example, dynamic estimates of the marginal value of capacity. Moreover, (2) we demonstrate that using these dynamic marginal capacity values directly as bid prices can lead to significant revenue loss as compared to using our heuristic to improve them. Finally, (3) we investigate numerically how much revenue performance is lost due to the confinement to product combinations that can be represented by a bid price.The heuristic is not restricted to a particular choice model and can be combined with any method that provides us with estimates of the marginal values of capacity. In our numerical experiments, we test the heuristic on some popular networks examples taken from peer literature. We use a multinomial logit choice model which allows customers from different segments to have products in common that they consider to purchase. In most problem instances, our heuristic policy results in significant revenue gains over some currently available alternatives at low computational cost.

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Copy reference link   DOI: 10.2139/ssrn.2142283

Abstract: Gold has been a store of value for centuries and a safe haven for investors in the pastdecades. However, the increased investment in gold for speculative or hedging purposes has changed the safe haven property. We demonstrate theoretically and empirically that investor behaviour has the potential to destroy the safe haven property of gold. The results suggest that an asset cannot be both an investment asset and an effective safe haven asset. This finding has important implications for financial stability since assets are more likely to exhibit excess comovement and volatility in the absence of a safe haven.

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Copy reference link   DOI: http://dx.doi.org/10.1016/j.jbankfin.2011.05.019

Abstract: This paper studies the spread of the Global Financial Crisis of 2007–2009 from the financial sector to the real economy by examining ten sectors in 25 major developed and emerging stock markets. The analysis tests different channels of financial contagion across countries and sectors and finds that the crisis led to an increased co-movement of returns among financial sector stocks across countries and between financial sector stocks and real economy stocks. The results demonstrate that no country and sector was immune to the adverse effects of the crisis limiting the effectiveness of portfolio diversification. However, there is clear evidence that some sectors in particular Healthcare, Telecommunications and Technology were less severely affected by the crisis.

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Copy reference link   DOI: 10.1111/j.1937-5956.2011.01251.x

Abstract: Supply chain risk management (SCRM) is a nascent area emerging from a growing appreciation for supply chain risk by practitioners and by researchers. However, there is diverse perception of research in supply chain risk because these researchers have approached this area from different domains. This paper presents our study of this diversity from the perspectives of operations and supply chain management scholars: First, we reviewed the researchers' output, i.e., the recent research literature. Next, we surveyed two focus groups (members of Supply Chain Thought Leaders and International SCRM groups) with open-ended questions. Finally, we surveyed operations and supply chain management researchers during the 2009 INFORMS meeting in San Diego. Our findings characterize the diversity in terms of three “gaps”: a definition gap in how researchers define SCRM, a process gap in terms of inadequate coverage of response to risk incidents, and a methodology gap in terms of inadequate use of empirical methods. We also list ways to close these gaps as suggested by the researchers.

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Copy reference link   DOI: doi:10.1007/s10696-011-9086-3

Abstract: This paper studies the problem of scheduling working hours of team drivers in European road freight transport where a sequence of lambda locations must be visited within given time windows. Since April 2007 working hours of truck drivers in the European Union must comply with regulation (EC) No 561/2006. These regulations impose standard limits on the daily driving times of truck drivers and extended daily limits that may only be used twice a week for each driver. We present a depth-first-breadth-second search method which can find a feasible schedule complying with standard daily driving time limits in O(lambda^2) time, if such a schedule exists. Furthermore, we show that this method can also be used to find schedules complying with regulation (EC) No 561/2006 if daily driving times may exceed the standard limit.

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Copy reference link   DOI: doi:10.1007/s10951-011-0249-6

Abstract: This paper presents and studies the Canadian Truck Driver Scheduling Problem (CAN-TDSP) which is the problem of determining whether a sequence of locations can be visited within given time windows in such a way that driving and working activities of truck drivers comply with Canadian Commercial Vehicle Drivers Hours of Service Regulations. Canadian regulations comprise the provisions found in U.S. hours of service regulations as well as additional constraints on the maximum amount of driving and the minimum amount of off-duty time on each day. We present two heuristics and an exact approach for solving the CAN-TDSP. Computational experiments demonstrate the effectiveness of our approaches and indicate that Canadian regulations are significantly more permissive than U.S. hours of service regulations.

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Copy reference link   DOI: 10.1016/j.ijresmar.2012.03.001

Abstract: The methodological discussion on the calibration of aggregate marketing response models has shifted away from how to obtain usable input for optimization toward how to avoid biases in statistical estimation. The purpose of this article is to remind researchers that such calibration is performed either to support managers in their marketing-mix decisions or to create general knowledge that leads to a better understanding of marketing relationships and thus indirectly supports decisions. Both goals require response models that are optimizable. The models must also be implementable if actual decision support is the objective. Herein, I identify several aspects for which these requirements are not always fulfilled: First, the appropriateness of the chosen functional form of the marketing response models is rarely discussed, although different forms imply quite different optimal solutions. Second, endogeneity is taken into account by structural equations, even though we lack sufficient information on how managers reach their decisions. Third, estimation methods for response models are often evaluated based on goodness-of-fit, while an assessment of their usefulness for subsequent optimization is neglected. Therefore, I provide recommendations for improving the current practice by better specifying the response function and undertaking more simulation-based evaluations of the best estimation method for use in subsequent optimization. With respect to implementation, usability can be facilitated using spreadsheets and heuristics. Moreover, gaining generalizable and replicable knowledge requires better documentation of results, which can be achieved through providing elasticities and as many details as are necessary to replicate a study, thereby enabling faster learning.

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Copy reference link   DOI: 10.4155/cmt.12.62

Abstract: This article examines the different approaches that companies can take to setting targets for the reduction of carbon emissions from their logistics operations. The research suggests that target-setting practices differ widely in this field. It is common for firms simply to apply corporate-level targets to logistics, despite the fact that carbon abatement potential and cost–effectiveness vary by function and activity. A small minority of firms have systematically analyzed the possible carbon savings from specific interventions and technologies. To improve their credibility and consistency, carbon reduction targets need to conform to certain principles. The article proposes a series of principles applicable to the decarbonization of logistics. It is based mainly on a literature review, semi-structured interviews with a sample of logistics managers and involvement in an industry-wide initiative to cut logistics-related carbon emissions.

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Copy reference link   DOI: http://dx.doi.org/10.1016/j.jempfin.2011.12.002

Abstract: The aim of this study is to provide a comprehensive description of the dependence pattern of stock returns by studying a range of quantiles of the conditional return distribution using quantile autoregression. This enables us to study the behavior of extreme quantiles associated with large positive and negative returns in contrast to the central quantile which is closely related to the conditional mean in the least-squares regression framework. Our empirical results are based on 30 years of daily, weekly and monthly returns of the stocks comprised in the Dow Jones Stoxx 600 index. We find that lower quantiles exhibit positive dependence on past returns while upper quantiles are marked by negative dependence. This pattern holds when accounting for stock specific characteristics such as market capitalization, industry, or exposure to market risk.

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Copy reference link   DOI: 10.3905/jai.2012.14.4.026

Abstract: The volatility of equity returns generally exhibits an asymmetric reaction to positive and negative shocks. Economic explanations for this phenomenon are leverage and a volatility feedback effect. This article studies the volatility of gold and demonstrates that there is an inverted asymmetric reaction to positive and negative shocks—positive shocks increase volatility more than negative shocks. The author argues that this effect is related to the safe-haven property of gold. Investors interpret positive gold price changes as a signal for future adverse conditions and uncertainty in other asset markets. This introduces uncertainty in the gold market and thus higher volatility. The empirical results hold for gold bullion and gold coins denominated in different currencies and for different return frequencies, sample periods, and distributional assumptions. Finally, the author shows that the inverted volatility effect of gold can lower the aggregate risk of a portfolio for specific correlation levels.

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Copy reference link   DOI: http://dx.doi.org/10.1016/j.enpol.2012.08.049

Abstract: The reduction of greenhouse gases (GHG) is a highly prevalent public policy goal among European Union member countries. In the new White Paper on transport, the role of road freight transports in this is strongly emphasized. This far, however, the efficiency practices utilised in logistics firms are less studied. Drawing from policy goals and new survey data on 295 road transport firms our results show that hauliers are aware of the possible energy efficiency actions but lack the knowledge and resources to fully utilize them. Energy efficiency seems also to be unimportant for many shippers, so there are no incentives for hauliers to improve it. Examples from various countries show that clear energy efficiency improvements can be achieved with active cooperation between hauliers, shippers and policy makers. Such cooperation can be developed in Finland through the sectoral energy efficiency agreements. The novelty and the utility of these results allow scholars to answer important open questions in the national-level determinants of enhancing energy efficiency practices among road freight hauliers, and contribute to our understanding of how these can be fostered in public policies.

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Copy reference link   DOI: 10.1287/trsc.1110.0382

Abstract: The U.S. truck driver scheduling problem (US-TDSP) is the problem of visiting a sequence of λ locations within given time windows in such a way that driving and working activities of truck drivers comply with U.S. hours-of-service regulations. In the case of single time windows it is known that the US-TDSP can be solved in O(λ3) time. In this paper, we present a scheduling method for the US-TDSP that solves the single time window problem in O(λ2) time. We show that in the case of multiple time windows the same complexity can be achieved if the gap between subsequent time windows is at least 10 hours. This situation occurs, for example, if, because of opening hours of docks, handling operations can only be performed between 8.00 a.m. and 10.00 p.m. Furthermore, we empirically show that for a wide range of other problem instances the computational effort is not much higher if multiple time windows are considered.

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Copy reference link   DOI: doi:10.1007/s13676-012-0014-9

Abstract: Truck driver scheduling problems are important subproblems of real-life vehicle routing and scheduling problems because rest periods required by government regulations have a significant impact on travel and arrival times and vehicle routes generated without considering these regulations are often practically infeasible. This paper presents a mixed integer programming formulation and a dynamic programming approach for solving a variant of the truck driver scheduling problem in which truck drivers may only rest at customer locations and at suitable parking lots. The objective of the problem is to find a truck driver schedule with minimal duration. The model presented in this paper is very flexible and can be configured to consider different sets of rules imposed by government regulations and union contracts. The effectiveness of the dynamic programming approach is demonstrated for working hour regulations in the United States and in the European Union.

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Copy reference link   DOI: 10.1016/j.cor.2011.05.021

Abstract: In September 2008 new regulations for managing heavy vehicle driver fatigue entered into force in Australia. According to the new regulations there is a chain of responsibility ranging from drivers to dispatchers and shippers and thus, carriers must explicitly consider driving and working hour regulations when generating truck driver schedules. This paper presents and studies the Australian Truck Driver Scheduling Problem (AUS-TDSP) which is the problem of determining whether a sequence of locations can be visited within given time windows in such a way that driving and working activities of truck drivers comply with Australian Heavy Vehicle Driver Fatigue Law.

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Abstract: Marketing budget decisions are critical and should be fact based rather than intuitive. Profit can be improved by better allocating a fixed budget across products or regions. The Excel-based decision support model presented in this article makes it possible to determine near-optimal marketing budgets and represents an innovative and feasible solution to the dynamic marketing allocation budget problem for multi-product, multi-country firms. The model accounts for marketing dynamics and a product's growth potential as well as for trade-offs with respect to marketing effectiveness and profit contribution. It was successfully implemented at Bayer, one of the world's largest firms in the pharmaceuticals and chemicals business. The profit improvement potential in this company was more than 50 % and worth nearly EUR 500 million in incremental discounted cash flows.

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Copy reference link   DOI: doi:10.1007/s11116-012-9386-9

Abstract: This article analyzes the concept of logistics networks in the context of behavioral freight transport modeling. Starting from the basic definition of networks, the different perceptions of networks in transportation science and logistics are worked out. The micro‐macro gap, as a main challenge in freight transport modeling, is explained by the existence of logistics networks on a meso level. A taxonomy of modeling methods dealing with logistics networks is defined, based on two characteristics: the changeability of networks within models (fixed, partially variable and variable networks) and the form of cost functions mapped (economies of scale, constant average cost, and diseconomies of scale). For each category, different possible modeling methods and their application in existing freight transport models are discussed. A special focus is placed on methodologies and models that map variable networks.

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