@article{WeissGarloff, author = {Weiss, Matthias and Garloff, Alfred}, title = {Skill-biased technological change and endogenous benefits: The dynamics of unemployment and wage inequality}, series = {Applied Economics}, volume = {43}, journal = {Applied Economics}, number = {7}, publisher = {Taylor \& Francis}, issn = {1466-4283}, doi = {10.1080/00036840802599933}, url = {http://nbn-resolving.de/urn:nbn:de:0168-ssoar-242195}, pages = {811 -- 821}, abstract = {In this paper, we study the effect of skill-biased technological change on unemployment and wage inequality in the presence of a link between social benefits and average income. In this case, an increase in the productivity of skilled workers and hence their wage leads to an increase in average income and hence in benefits. The increased fallback income, in turn, makes unskilled workers ask for higher wages. As higher wages are not justified by respective productivity increases, unemployment rises. More generally, we show that skill-biased technological change leads to increasing unemployment of the unskilled and to a moderately increasing wage inequality when benefits are endogenous. The model provides a theoretical explanation for diverging dynamics in wage inequality and unemployment under different social benefits regimes: Analyzing the social legislation in 14 countries, we find that benefits are linked to the evolution of average income in Continental Europe but not in the U.S. and the UK. Given this institutional difference, our model predicts that skill-biased technological change leads to rising unemployment in Continental Europe and rising wage inequality in the U.S. and the UK....}, language = {en} } @article{KellnerUtz, author = {Kellner, Florian and Utz, Sebastian}, title = {Sustainability in supplier selection and order allocation: Combining integer variables with Markowitz portfolio theory}, series = {Journal of Cleaner Production}, volume = {214}, journal = {Journal of Cleaner Production}, publisher = {Springer Nature}, doi = {10.1016/j.jclepro.2018.12.315}, pages = {462 -- 474}, abstract = {This research presents a decision support methodology for the multi-criteria supplier selection and order allocation problem. The proposed approach supports purchasing managers in assembling mid-term supplier portfolios while making them aware of the trade-offs between the supplier sustainability, the purchasing costs, and the overall supply risk. First, we propose a multi-objective optimization model with three objectives: to maximize the supplier sustainability, to select the supplier portfolio with the lowest purchasing costs, and to minimize the supply risk. Our model extends existing mathematical approaches that follow the portfolio theory fathered by H. Markowitz by integrating the aspect 'risk' into the supplier selection problem. Secondly, since we allow for integer variables in our model—in contrast to the classical Markowitz portfolio theory—we use the ε-constraint method to visualize the efficient surface. The possibility of considering the non-dominated set of supplier portfolios is advantageous for purchasing managers as they gain a picture of the different optimal supplier portfolios and are able to analyze the trade-offs between the different purchasing goals before making a decision. Finally, we illustrate the applicability of the proposed methodology in a real-world supplier selection and order allocation case from the automotive industry. In the example case, we identify 1754 optimal supplier portfolios that may be assembled based on the eight available suppliers. Our analyses show that each optimal portfolio consists of two suppliers, with one specific supplier being included in each portfolio. Furthermore, four suppliers are not part of any optimal solution.}, language = {en} } @article{KellnerLienlandUtz, author = {Kellner, Florian and Lienland, Bernhard and Utz, Sebastian}, title = {A multi-criteria decision-making approach for assembling optimal powertrain technology portfolios in low GHG emission environments}, series = {Journal of Industrial Ecology}, volume = {25}, journal = {Journal of Industrial Ecology}, number = {6}, publisher = {Wiley}, doi = {10.1111/jiec.13148}, pages = {1412 -- 1429}, abstract = {Environmental regulations force car manufacturers to renew the powertrain technology portfolio offered to the customer to comply with greenhouse gas (GHG) emission targets. In turn, automotive companies face the task of identifying the "right" powertrain technology portfolio consisting of, for example, internal combustion engines and electric vehicles, because the selection of a particular powertrain technology portfolio affects different company targets simultaneously. What makes this decision even more challenging is that future market shares of the different technologies are uncertain. Our research presents a new decision-support approach for assembling optimal powertrain technology portfolios while making decision-makers aware of the trade-offs between the achievable profit, the achievable market share, the market share risk, and the GHG emissions generated by the selected vehicle fleet. The proposed approach combines "a posteriori" decision-making with multi-objective optimization. In an application case, we feed the outlooks of selected market studies into the proposed decision-support system. The result is a visualization and analysis of the current real-world decision-making problem faced by many automotive companies. Our findings indicate that for the proposed GHG restriction at work in 2030 in the European Union, no optimal powertrain technology portfolio with less than 35\% of vehicles equipped with an electric motor exists.}, language = {en} } @article{Lienland, author = {Lienland, Bernhard}, title = {The Implementation of a Cash-Flow-Based Mathematical R\&D Project Selection Model}, series = {International Journal of Information Technology Project Management (IJITPM)}, volume = {7}, journal = {International Journal of Information Technology Project Management (IJITPM)}, number = {3}, publisher = {IGI Global}, doi = {10.4018/IJITPM.2016070102}, pages = {22}, abstract = {Customer project selection is a challenge for many industrial companies. An inappropriate project selection approach can lead to constraint violations, high fixed costs, and suboptimal portfolios. To overcome these problems a cash-flow-based linear optimization model was developed in partnership with a tier-1 automotive supplier. Implementation barriers had been verified through a case study conducted at two organizational hierarchies. Results suggest that an application at the operating levels is possible. At higher levels, though, product and firm complexity require major implementation efforts. This article serves theorists as well as practitioners in multiple regards. First, an overview of existing project selection methods and their application in practice is provided. Additionally, the supplier's current appraisal process is depicted. Second, operations research implementation barriers are identified and validated for the adoption of the proposed mathematical project selection approach. Third, a guideline including procedures to overcome experienced difficulties is presented.}, language = {en} } @article{NeumuellerLaschKellner, author = {Neum{\"u}ller, Claudia and Lasch, Rainer and Kellner, Florian}, title = {Integrating sustainability into strategic supplier portfolio selection}, series = {Management decision}, volume = {54}, journal = {Management decision}, number = {1}, publisher = {Emerald}, doi = {10.1108/MD-05-2015-0191}, pages = {194 -- 221}, abstract = {Purpose - The purpose of this paper is to propose a comprehensive methodology and a problem-specific model for the configuration of the optimal strategic supplier portfolio in terms of traditional, performance-related objectives and sustainability targets. Design/methodology/approach - To bridge the research gap, i.e., to align strategic supplier portfolio selection with corporate sustainability targets, a hybrid model of the analytic network process (ANP) and goal programming (GP) is developed. To validate the model, a case example is presented and managerial feedback is collected. Findings - By enabling the integration of sustainability targets into strategic supplier portfolio configuration, the hybrid ANP-GP model contributes to research in the area of sustainable supply chain management. Results indicate that simplifying the model by omitting one or more details may lead to unfortunate actions. Research limitations/implications - The model has been applied using a case example in the automotive industry. To strengthen the findings, it should be examined under other terms as well. Practical implications - Integrating economic, environmental, and social targets into strategic supplier portfolio configuration reduces supply risks and promotes the achievement of the sustainability goals of the purchasing company. Social implications - Strategic supplier selection counts among the decisions that have an impact on the environment and society for several years. Configuring economically rational, environmentally friendly, and socially responsible supplier bases supports worldwide efforts towards sustainable development. Originality/value - Although sustainable supplier selection has gained importance in recent years, this is the first time that a comprehensive model for the determination of the optimal strategic supplier portfolio in terms of performance-related objectives and sustainability targets has been proposed.}, language = {en} } @unpublished{KellnerLienlandUtz, author = {Kellner, Florian and Lienland, Bernhard and Utz, Sebastian}, title = {An a Posteriori Multi-Objective Supplier Portfolio Selection Approach Under Risk and Sustainability Considerations}, series = {SSRN Electronic Journal}, journal = {SSRN Electronic Journal}, doi = {10.2139/ssrn.2901390}, pages = {39}, abstract = {This research presents a novel, state-of-the-art methodology for solving the multi-criteria supplier selection problem under risk and sustainability considerations. The approach combines multi-objective optimization with the analytic network process to meet the requirements for supplier portfolio configuration with sustainability considerations. To integrate the aspect 'risk' into the supplier selection problem, this research develops a multi-objective optimization model based on the investment portfolio theory introduced by Markowitz. The proposed model is a non-standard portfolio selection problem with four objectives: to minimize the purchasing costs, to select the supplier portfolio with the highest logistics service, to minimize the supply risk, and to order as much as possible from those suppliers with outstanding sustainability performance. The optimization model, which has three linear and one quadratic objective function, is solved by an algorithm which analytically computes a set of efficient solutions and provides graphical decision support by a visualization of the complete and exactly-computed Pareto front (a posteriori approach). The possibility of computing all Pareto optimal supplier portfolios is beneficial for decision makers as they can compare all optimal solutions at once, identify the trade-offs between the criteria, and study how the different aspects of supplier portfolio configuration may be balanced to finally choose the composition that satisfies the purchasing company's strategy at best. The approach has been applied to a real-world supplier portfolio configuration case to demonstrate its applicability and to analyze how the consideration of sustainability requirements may affect the traditional supplier selection and purchasing goals in a real-life setting.}, language = {en} } @article{KellnerIgl, author = {Kellner, Florian and Igl, Johannes}, title = {Greenhouse gas reduction in transport: analyzing the carbon dioxide performance of different freight forwarder networks}, series = {Journal of Cleaner Production}, volume = {99}, journal = {Journal of Cleaner Production}, publisher = {Elsevier}, doi = {10.1016/j.jclepro.2015.03.026}, pages = {177 -- 191}, abstract = {There are growing concerns in the food industry about how supply chains can be managed in a more sustainable way. When distribution activities are outsourced to a logistics service provider (LSP), shippers need to evaluate the LSPs they may (potentially) engage in order to ensure that supply chain sustainability goals are met. In this paper, we present a methodology for LSP evaluation and focus on the ecological dimension of sustainability. We examine how the network carbon footprint of a real-world distribution system is affected by the LSP network that is chosen to forward goods from production facilities to customers. To do this, we analyze the shipment data of an existing Fast Moving Consumer Goods (FMCG) manufacturer. A quantitative distribution network model is set up to study the network carbon footprint of 125 scenarios. Real-world shipments are forwarded via five generic, idealized types of LSP networks. In total, 625 network carbon footprints, specified by three distribution logistics variables and the structure of the LSP network, have been calculated. The results show that LSP structures practicing a geographically decentralized consolidation of shipments are most efficient in reducing of greenhouse gas (GHG) emissions. Furthermore, the effects of changing the manufacturer's and the LSP's strategies for deciding on the tonnage to be forwarded via the LSP network or moved by direct transports are quantified. Finally, we estimate the GHG effect of improving the capacity utilization of the vehicles that move the products.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Generating greenhouse gas cutting incentives when allocating carbon dioxide emissions to shipments in road freight transportation}, series = {OR Spectrum}, volume = {44}, journal = {OR Spectrum}, number = {3}, publisher = {Springer Nature}, doi = {10.1007/s00291-022-00675-y}, pages = {833 -- 874}, abstract = {Road freight transportation accounts for a great share of the anthropogenic greenhouse gas (GHG) emissions. In order to provide a common methodology for carbon accounting related to transport activities, the European Committee for Standardization has published the European Norm EN-16258. Unfortunately, EN-16258 contains gaps and ambiguities and leaves room for interpretation, which makes the comparison of the environmental performance of different logistics networks still difficult and hinders the identification of best practices. This research contributes to the identification of particularly meaningful principles for the allocation of GHG to shipments in road freight transportation by presenting an analytical framework for studying the performance of the EN-16258 allocation schemes with respect to accuracy, fairness, and the GHG minimizing incentive. In doing so, we continue previous studies that analyzed two important aspects of the EN-16258 allocation rules: accuracy and fairness. This study provides further insights into this allocation problem by investigating the incentive power of the different allocation schemes to opt for the GHG minimal way of running a road freight network. First, we complement the list of transport scenarios introduced in prior studies and present two novel scenarios. Second, we carry out a series of numerical experiments to compare the EN-16258 allocation rules with respect to accuracy, fairness, and the GHG minimizing incentive. We find that the results may differ significantly for the two scenarios, suggesting a case-by-case recommendation. This is particularly interesting because the first scenario confirms the results of the prior studies, while the second scenario rather contradicts them.}, language = {en} } @unpublished{KellnerSchneiderbauer, author = {Kellner, Florian and Schneiderbauer, Miriam}, title = {Further Insights into the Allocation of Greenhouse Gas Emissions to Shipments in Road Freight Transportation: The Pollution Routing Game}, series = {SSRN Electronic Journal}, journal = {SSRN Electronic Journal}, doi = {10.2139/ssrn.3221764}, abstract = {At present, there is no globally accepted standard for the allocation of greenhouse gas (GHG) emissions to shipments in road freight transportation. The only official international standard for emission calculation of transport operations is the European Norm EN-16258. However, even this norm still allows choosing from several alternative emission allocation schemes. This research aims to harmonize the process of GHG declarations for supply chains by identifying among all allocation units specified by EN-16258 the one that describes a shipment's contribution to GHG emissions best. For this purpose, concepts of the cooperative game theory are used. First, we develop three transport scenarios that allow studying a shipment's effect on GHG: a vehicle routing problem, a network flow model, and a mixed scenario. Our approach extends previous research projects because we take into account that shipment characteristics in terms of origin, destination, weight, and volume consume transport capacities to different degrees, impact the routing of the commercial vehicles and, thus, determine GHG. Second, we present the results of a computational study that bases on the introduced transport scenarios and that compares the allocation vectors resulting from the EN-16258 allocation rules with the Shapley value, which serves as a benchmark for a shipment's contribution to GHG. Furthermore, we show how often the EN-16258 allocation principles are in line with a set of game theoretical fairness criteria. The results indicate that the allocation unit 'distance' is the closest to the game theory benchmark and most often in line with game theoretical fairness criteria.}, language = {en} } @article{FuchsBeckLienlandetal., author = {Fuchs, Christoph and Beck, Daniel and Lienland, Bernhard and Kellner, Florian}, title = {The role of IT in automotive supplier supply chains}, series = {Journal of Enterprise Information Management}, volume = {31}, journal = {Journal of Enterprise Information Management}, number = {1}, publisher = {emerald insight}, doi = {10.1108/JEIM-03-2017-0038}, pages = {64 -- 88}, abstract = {Purpose The purpose of this paper is to explore the impact of information technology (IT) on supply chain performance in the automotive industry. Prior studies that analyzed the impact of IT on supply chain performance report results representing the situation of the "average industry." This research focuses on the automotive industry because of its major importance in many national economies and due to the fact that automotive supply chains do not represent the supply chain of the average industry. Design/methodology/approach A research model is proposed to examine the relationships between IT capabilities, supply chain capabilities, and supplier performance. The model divides IT capabilities into functional and data capabilities, and supply chain capabilities into internal process excellence and information sharing. Data have been collected from 343 automotive first-tier suppliers. Structural equation modeling with partial least squares is used to analyze the data. Findings The results suggest that functional capabilities have the greatest impact on internal process excellence, which in turn enhances supplier performance. However, frequent and adequate information sharing also contributes significantly to supplier performance. Data capabilities enable supply chain capabilities through their positive impact on functional capabilities. Practical implications The findings will help managers to understand the effect of IT implementation on company performance and to decide whether to invest in the expansion of IT capacities. Originality/value This research reports the impact of IT on supply chain performance in one of the most important industries in many industrialized countries, and it provides a new perspective on evaluating the contribution of IT on firm performance.}, language = {en} } @article{LienlandBaumgartnerKnubben, author = {Lienland, Bernhard and Baumgartner, Alexander and Knubben, Evelyn}, title = {The undervaluation of corporate reputation as a supplier selection factor}, series = {Journal of Purchasing and Supply Management}, volume = {19}, journal = {Journal of Purchasing and Supply Management}, number = {2}, publisher = {Elsevier}, issn = {1478-4092}, doi = {10.1016/j.pursup.2013.04.001}, pages = {84 -- 97}, abstract = {Prior research studies on supplier selection factors assess vendor reputation as a low ranked criterion. Reputation in these articles, however, only refers to the position in the industry, without considering the role of the final customer. Our results from a survey with 565 individuals suggest that the end user as a stakeholder should be also considered when analyzing a vendor's prestige. We demonstrate that a supplier's standing has negative as well as positive reputational effects on the buyer. Depending on the relevance of the purchased good as well as the reputation of the supplier and the buyer, low/high-ranked ingredients significantly decrease/increase the final customer's perception of the buyer.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Exploring the impact of urbanization on consumer goods distribution networks}, series = {Journal of Asian Business and Economic Studies}, volume = {28}, journal = {Journal of Asian Business and Economic Studies}, number = {2}, publisher = {Emerald}, doi = {10.1108/JABES-12-2019-0127}, pages = {101 -- 120}, abstract = {Purpose Due to the growing percentage share of urban dwellers, the physical distribution of products faces altering conditions. This research explores the effects that urbanization has on the performance of a fast-moving consumer goods distribution network. A focus is set on changes in distribution cost, the cost-minimal network design, and greenhouse gas emissions. Design/methodology/approach The analyses are based on a quantitative distribution network model of an existing manufacturer of consumer goods. Findings The results indicate that the foreseen population shift will affect the network's economic and environmental performance. Effects are, among others, due to differences in the efficiency of supplying urban and nonurban regions. The combined effects of urbanization and the development of the population size will even more affect the network's performance. Originality/value Research dealing with distribution logistics and urbanization primarily focuses on city logistics. In this paper, the object of analysis is the entire distribution system.}, language = {en} } @article{NeumuellerKellnerGuptaetal., author = {Neum{\"u}ller, Claudia and Kellner, Florian and Gupta, Jatinder N.D. and Lasch, Rainer}, title = {Integrating three-dimensional sustainability in distribution centre selection: the process analysis method-based analytic network process}, series = {International Journal of Production Research}, volume = {53}, journal = {International Journal of Production Research}, number = {2}, publisher = {Taylor \& Francis}, doi = {10.1080/00207543.2014.939241}, pages = {409 -- 434}, abstract = {In this paper, we propose a combined methodology for the selection of distribution centres (DCs) by integrating and balancing economic, environmental and social sustainability aspects. The analytic network process (ANP) permits to systematically evaluate possible DCs on the basis of a situation-specific decision structure. A systematic development of the decision networks, which is one of the core challenges using the ANP, is supported by the process analysis method which we extend for that purpose. The validity and soundness of the proposed framework are demonstrated by means of a case study. The case study results reveal that omitting aspects of sustainability can lead to unfortunate results.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Insights into the effect of traffic congestion on distribution network characteristics - a numerical analysis based on navigation service data}, series = {International Journal of Logistics Research and Applications}, volume = {19}, journal = {International Journal of Logistics Research and Applications}, number = {5}, publisher = {Taylor \& Francis}, doi = {10.1080/13675567.2015.1094043}, pages = {395 -- 423}, abstract = {This research studies effects that the average increase in travel times due to road traffic congestion has on characteristics of an existing distribution network. It presents the most detailed estimate of 'on-the-road' effects on distribution network characteristics up to now, from the network modelling perspective and from the processed data point of view. A concrete network model allowing for the representation of all relevant transportation flows is presented. The processed traffic information relies on navigation service data. The use of such data allows the requirements that arise for the traffic analysis of a whole distribution network to be met. It is shown that this data source may considerably contribute in forthcoming research. The effects of traffic congestion are quantified to get insights into the extent to which regular traffic congestion affects distribution network characteristics and to understand the mitigating effect when the number of distribution centres is increased.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Allocating greenhouse gas emissions to shipments in road freight transportation: Suggestions for a global carbon accounting standard}, series = {Energy Policy}, volume = {98}, journal = {Energy Policy}, address = {Elsevier}, doi = {10.1016/j.enpol.2016.09.030}, pages = {565 -- 575}, abstract = {The European Norm EN 16258 was published in 2012 to provide a common methodology for the calculation and declaration of energy consumption and greenhouse gas emissions related to any transport operation. The objective was to offer a pragmatic and scientifically-acceptable approach that allows a wide group of users to prepare standardized, accurate, credible, comparable, and verifiable energy consumption and emission declarations. However, in its current form, EN 16258 contains gaps and ambiguities, and leaves room for interpretation, which makes comparisons of supply chains difficult. This research aims to overcome the shortcomings in the domain of allocating emissions from road freight transport operations to single shipments. Based on a discussion of emission drivers and the results of numerical experiments comparing the allocation vectors created by the EN 16258 allocation rules with those generated by the Shapley value, which is claimed to be the benchmark, 'distance' is identified as the single most useful unit for bridging the trade-off between accuracy and simplicity better than the other recommended allocation schemes. Thus, this paper claims that future versions of EN 16258 should only allow the allocation unit 'distance.' This will promote the accurateness, simplicity, consistency, transparency, and comparability of emission declarations.}, language = {en} } @article{KellnerUtz, author = {Kellner, Florian and Utz, Sebastian}, title = {An inverse optimization approach for studying sustainability preferences in sourcing decisions}, series = {Journal of Cleaner Production}, volume = {483}, journal = {Journal of Cleaner Production}, publisher = {Elsevier}, doi = {10.1016/j.jclepro.2024.144305}, abstract = {Throughout many societies around the globe, there is growing awareness of the urgent need for the transition towards a sustainable economy. Research shows that buying firms have substantial leverage to initiate sustainable development by controlling the sustainable performance of their suppliers. In that context, this article presents a novel methodology based on inverse optimization to derive the implicit preferences of decision-makers in the trade-off between traditional sourcing objectives and sustainability in the supplier selection and order allocation process. The derived implicit preferences can then be used for further analyses to gain a better understanding of the characteristics of purchasing managers and sourcing situations that come with particularly high/low preferences placed on sustainability. Since the inverse optimization approach is computationally resource-intensive and consumes a significant amount of time, we present a scalable state-of-the-art cloud architecture that allows solving an arbitrary number of optimization programs in an acceptable amount of time. We demonstrate the feasibility of the proposed methodology in a real-world case. In doing so, we test how important sustainability aspects are in the supplier selection and order allocation decisions of one of the world's largest automotive parts manufacturers.}, language = {en} } @incollection{OttoLukeschBrabaenderetal., author = {Otto, Andreas and Lukesch, Maximilian and Brab{\"a}nder, Christian and Kellner, Florian}, title = {Konsumg{\"u}terdistribution}, series = {Handbuch Produktions- und Logistikmanagement in Wertsch{\"o}pfungsnetzwerken}, booktitle = {Handbuch Produktions- und Logistikmanagement in Wertsch{\"o}pfungsnetzwerken}, editor = {Corsten, Hans and G{\"o}ssinger, Ralf and Spengler, Thomas S.}, publisher = {De Gruyter Brill}, isbn = {9783110473803}, doi = {10.1515/9783110473803-039}, pages = {737 -- 758}, abstract = {Der Beitrag untersucht die Konsumg{\"u}terdistribution aus systemtheoretischer Sicht. Der Fokus liegt auf der logistischen Funktion der Warenverteilung mit Einschr{\"a}nkung auf schnelldrehende Konsumg{\"u}ter (FMCG) in Deutschland. Der eng an die Empirie angelehnten Beschreibung der Funktion, der Strukturelemente (Kunden, Hersteller, Handel, Logistikdienstleister, Sortimente, Sendungen, Betriebsmittel) sowie der Prozesse (Netzpla-nung, Distributionsplanung, Auftragsabwicklung, Transporte) folgt die Diskussion prinzipieller Arbeitsfelder (Systemf{\"u}hrerschaft, B{\"u}ndelung, Beschleunigung, Segmentierung, Kanalintegration, Kooperation) zur Umgestaltung der Konsumg{\"u}terdistribution.}, language = {de} } @article{BraunKunklerKellner, author = {Braun, Maximilian and Kunkler, Jan and Kellner, Florian}, title = {Towards Sustainable Cities: Utilizing Floating Car Data to Support Location-Based Road Network Performance Measurements}, series = {Sustainability}, volume = {12}, journal = {Sustainability}, number = {19}, publisher = {MDPI}, doi = {10.3390/su12198145}, abstract = {Road network performance (RNP) is a key element for urban sustainability as it has a significant impact on economy, environment, and society. Poor RNP can lead to traffic congestion, which can lead to higher transportation costs, more pollution and health issues regarding the urban population. To evaluate the effects of the RNP, the involved stakeholders need a real-world data base to work with. This paper develops a data collection approach to enable location-based RNP analysis using publicly available traffic information. Therefore, we use reachable range requests implemented by navigation service providers to retrieve travel times, travel speeds, and traffic conditions. To demonstrate the practicability of the proposed methodology, a comparison of four German cities is made, considering the network characteristics with respect to detours, infrastructure, and traffic congestion. The results are combined with cost rates to compare the economical dimension of sustainability of the chosen cities. Our results show that digitization eases the assessment of traffic data and that a combination of several indicators must be considered depending on the relevant sustainability dimension decisions are made from.}, language = {en} } @article{ObermaierHofmannKellner, author = {Obermaier, Robert and Hofmann, Johann and Kellner, Florian}, title = {Webbasierte Fertigungssteuerung in der Praxis: Pruduktivit{\"a}tssteigerungen mit dem Manufacturing-Execution-Sytem MR-CM©}, series = {HMD Praxis der Wirtschaftsinformatik}, volume = {47}, journal = {HMD Praxis der Wirtschaftsinformatik}, number = {2}, publisher = {Springer Nature}, doi = {10.1007/BF03340455}, pages = {49 -- 59}, abstract = {Manufacturing-Execution-Systeme (MES) werden in der Fertigungsindustrie dazu eingesetzt, einen durchgehenden Informationsfluss zwischen den an der Fertigung beteiligten Systemen herzustellen. Von der Vernetzung aller an der Produktion beteiligten Systeme wird dabei eine gesteigerte Produktivit{\"a}t auf Shop-Floor-Ebene erwartet. Beim Durchlauf des beispielhaft gezeigten Fertigungsauftrages wurden durch den Einsatz von MR-CM©, einem von der Maschinen-fabrik Reinhausen entwickelten und implemen-tierten MES, bereits einige Produktivit{\"a}tspotenziale im Vergleich mit der konventionellen Abwicklung ohne Einsatz des MES deutlich. Diese resultieren im Wesentlichen aus der Eliminierung von nicht wertsch{\"o}pfenden Schnittstellenproblemen zwischen den an der Auftragsdurchf{\"u}hrung beteiligten Maschinen. Die erzielten Produktivit{\"a}tszuw{\"a}chse bestehen im Kern aus einer Verk{\"u}rzung der Maschinenr{\"u}stzeiten, was zu einer Reduktion der Produktionskosten und einer Zunahme der Produktionsflexibilit{\"a}t f{\"u}hrt und zu einer Reduzierung der Werkzeugbest{\"a}nde sowie der damit verbundenen Kapitalbindungskosten.}, language = {en} } @article{KunklerBraunKellner, author = {Kunkler, Jan and Braun, Maximilian and Kellner, Florian}, title = {Speed Limit Induced CO2 Reduction on Motorways: Enhancing Discussion Transparency through Data Enrichment of Road Networks}, series = {Sustainability}, volume = {13}, journal = {Sustainability}, number = {1}, publisher = {MDPI}, doi = {10.3390/su13010395}, abstract = {Considering climate change, recent political debates often focus on measures to reduce CO2 emissions. One key component is the reduction of emissions produced by motorized vehicles. Since the amount of emission directly correlates to the velocity of a vehicle via energy consumption factors, a general speed limit is often proposed. This article presents a methodology to combine openly available topology data of road networks from OpenStreetMap (OSM) with pay-per-use API traffic data from TomTom to evaluate such measures transparently by analyzing historical real-world circumstances. From our exemplary case study of the German motorway network, we derive that most parts of the motorway network on average do not reach their maximum allowed speed throughout the day due to traffic, construction sites and general road utilization by network participants. Nonetheless our findings prove that the introduction of a speed limit of 120 km per hour on the German autobahn would restrict 50.74\% of network flow kilometers for a CO2 reduction of 7.43\% compared to the unrestricted state.}, language = {en} } @article{LienlandZeng, author = {Lienland, Bernhard and Zeng, Li}, title = {A Review and Comparison of Genetic Algorithms for the 0-1 Multidimensional Knapsack Problem}, series = {International Journal of Operations Research and Information Systems (IJORIS)}, volume = {6}, journal = {International Journal of Operations Research and Information Systems (IJORIS)}, number = {2}, publisher = {IGI Global}, issn = {1947-9328}, doi = {10.4018/ijoris.2015040102}, pages = {11}, abstract = {The 0-1 multidimensional knapsack problem (MKP) is a well-known combinatorial optimization problem with several real-life applications, for example, in project selection. Genetic algorithms (GA) are effective heuristics for solving the 0-1 MKP. Multiple individual GAs with specific characteristics have been proposed in literature. However, so far, these approaches have only been partially compared in multiple studies with unequal conditions. Therefore, to identify the "best" genetic algorithm, this article reviews and compares 11 existing GAs. The authors' tests provide detailed information on the GAs themselves as well as their performance. The authors validated fitness values and required computation times in varying problem types and environments. Results demonstrate the superiority of one GA.}, language = {en} }