Globalizing a nonsmooth Newton method via nonmonotone path search

We give a framework for the globalization of a nonsmooth Newton method. In part one we start with recalling B. Kummer's approach to convergence analysis of a nonsmooth Newton method and state his results for local convergence. In part two we give a globalized version of this method. Our approach uses a path search idea to control the descent. After elaborating the single steps, we analyze and prove the global convergence resp. the local superlinear or quadratic convergence of the algorithm. In the third part we illustrate the method for nonlinear complementarity problem

Generation of the transport service offer with application to timetable planning considering constraints due to maintenance work

Line planning is an important step in strategic timetable planning in public transport. In this step the transport offer for the customer is generated by the public transport operator, whereby the resulting costs for the operator should be as deep as possible. Mathematical models for line planning allow to create optimized line plans quickly. Planners can use these models to rate and select different alternatives. This is particularly valuable under the aspect of increasing maintenance and construction tasks of the railway infrastructure. We show, that in this case, it is possible to create functional requirements for automated timetable creation from the result of line planning step. The practical use of the involved models is illustrated by a real application example

Kooperieren? Ja! Aber wie? : Chancen und Herausforderungen bei der Entwicklung einer Kooperationsplattform für urbane Güterlogistik in der Stadt Zürich

Die urbane Güterlogistik ist angesichts zunehmender Volumen und steigender Kundenanforderungen eine grosse Herausforderung. Eine quantitative Studie zeigt, dass eine Kooperation von Transporteuren nicht nur die Gesamtkosten senken, sondern auch die gefahrenen Kilometer reduzieren würde. Ein Geschäftsmodell basierend auf einer virtuellen Plattform zur Ermöglichung solcher Kooperation könnte also die Nachhaltigkeit fördern. Die Herausforderungen für ein derartiges Geschäftsmodell sind derzeit noch gross, doch könnten neue rechtliche Rahmenbedingungen und die zunehmende Digitalisierung der Märkte die Attraktivität solcher Plattformen erhöhen

Customers as investment objects : a new perspective on marketing

Customers have always considered as one of the most important assets of a firm. The concept of Customer Equity (Rust, Zeithaml, Lemon, 2000) has given this idea a conceptual and methodological foundation. Marketing can then be seen as the attempt to maximize Customer Equity by corresponding activities. For doing this, we focus on the Customer Lifetime Value (CLV) and ways for its maximization. While the CLV has become a well-studied concept in marketing with a lot of literature coverage, much less work has been done in developing methods how to increase CLV. As an active increase in CLV always requires some activities, it is coupled with costs, and a cost-benefit analysis has to be made. We develop a new model for such a cost-benefit-analysis, by considering a customer as an investment object: A customer treatment incurs costs today, while, on the other hand, it generates returns in the future, over the lifecycle of the customer. Since a customer can receive different forms of treatment, there are in fact different investment options available. When trying to increase the CLV, these options have to be compared to each other. By formalizing this approach in a quantitative model, we create a framework for describing the cost-benefit profile of an individual customer. With this framework, optimum treatments can be identified, and the optimum height of investment into a single customer can be determined

Automatisierte Linienplanung im öffentlichen Verkehr

Automatisierung und Digitalisierung sollen in der Bahnproduktion Kosten senken und die Kapazität der Infrastruktur erhöhen. Dazu müssen alle Planungsschritte in einem einheitlichen System abgebildet werden. Davon profitieren die Bahnkunden durch ein attraktiveres Angebot, höhere Pünktlichkeit und mehr Sicherheit. Die ZHAW beteiligt sich an dieser Entwicklung in Forschung und Lehre. Unter anderem wurde für den Schritt der Linienplanung eine Methode entworfen, die es erlaubt in kurzer Zeit kostenoptimale und kundenfreundliche Linienpläne zu erstellen

Generation of interactive questionnaires using YAWL-based workflow models

A concept is introduced in this article which has strong practical impact for computer aided system configuration. System configuration is a cumbersome and fault sensitive task while setting up systems in a broad range of business applications like ERP (enterprise resource planning) and other workflow-systems. Given a generic process or workflow model in YAWL-notation (yet another workflow language) or any other process modeling language like business process model and notation or WFMC (workflow management coalition), it could be stated that, by using a set of reduction rules as introduced, it is possible to generate a hierarchically structured tree of sub graphs of the workflow graph-representation. According to the notation used, authors call these sub graphs facts. The tree structure of the graph-representation on one hand and the logical relation between the branches and leafs of the tree on the other can be utilized to create a set of constraints and dependencies among the single facts. Some researchers showed that the nested branches can be associated to (predefined) questions with respect to the configuration of a workflow management system, for instance an ERP-application. They presented an algorithm which dynamically sorts the questions and answers in a maximum efficient configuration path, while working through the corresponding questionnaire. By combining the different elements as facts, constraints on questions, and configuration space, it is thus possible to algorithmically generate the efficient structured and interactive questionnaire for the configuration of workflow systems and algorithmically check the consistency (dead lock free, free of synchronization structural conflict) of the underlying workflow model. The concept was tested in the prototype of the interactive questionnaire for configuration of the web-service based ERP-Application Posity

Development of a prototype for the automated generation of timetable scenarios specified by the transport service intention

Within the next 5 to 10 years, public transport in Switzerland as well as in other European countries will experience major technological and organisational changes. However, changes will also take place on the customer side, resulting in different mobility behaviour and demand patterns. These changes will lead to additional challenges for transport service providers in private as well as public domains. Time to market will be a key success factor and it is unnecessary to mention that due to these factors the speed and flexibility of business processes in freight as well as in passenger transport industry have to be increased significantly. Within the railway value chain (line planning, timetabling and vehicle scheduling etc.) the coordination of the individual planning steps is a key success factor. SBB as the leading service provider in public transport in Switzerland has recognized this challenge and, together with various partners, initiated the strategic project Smart Rail 4.0. The ZHAW and especially the Institute for Data Analysis and Process Design (IDP) of the School of Engineering wants to be part of this transformation process and to contribute with research and educational activities. The IDP research therefore aims for the transformation of academic and scientific know-how to practical applicability. In a first step this concerns directly the current Smart Rail 4.0 TMS-PAS project activities, that concentrate on timetabling issues. The IDP project team considers the integration of the line planning and the timetabling process as crucial for practical applications. To address this in the current research project, we present an application concept that enables the integration of these two major process steps in the transport service value-chain. Although it turns out from our research, that the technical requirements for the integration of the process can be satisfied, rules and conditions for a closer cooperation of the involved business units, the train operating companies and the infrastructure operating company, have to be improved and to be worked out in more detail. In addition to a detailed application concept with use cases for the timetabling process we propose a methodology for computer aided timetable generation based on the central planning object known as ‘service intention’. The service intention can be used to iteratively develop the timetable relying on a ‘progressive feasibility assessment’, a feature that is requested in practice. Our proposed model is based on the ‘track-choice’ and line rotation extension of the commonly known method for the generation of periodic event schedules ‘PESP’. The extension makes use of the track infrastructure representation which is also used in the line planning and timetabling system Viriato. This system that is widely used by public transport planners and operators. With the help of Viriato, it is rather easy to configure the timetabling problem in sufficient detail. On the other side, the level of detail of the considered data is light enough to algorithmically solve practical timetabling problems of realistic sizes. Taking into consideration the technical and operational constraints given by rolling stock, station and track topology data on one hand, and the commercial requirements defined by a given line concept on the other, the method presented generates periodic timetables including train-track assignments. In the first step, the standardized data structure ‘service intention’ represents the line concept consisting of train paths and frequencies. Due to the utilization of infrastructure-based track capacities, we are also able to assess the feasibility of the line concept given. Additionally, the method allows for handling temporary resource restrictions (e.g. caused by construction sites or operational disturbances). In order to assess the performance of the resulting timetable we present a framework for performance measurement that addresses the customer convenience (in terms of start-to-end travel time) as well as operational stability requirements (in terms of delay sensitivity and critical relations)

Improvement of maintenance timetable stability based on iteratively assigning event flexibility in FPESP

In the operational management of railway networks, an important requirement is the fast adaptation of timetable scenarios, in which operational disruptions or time windows with temporary unavailability of infrastructure, for instance during maintenance time windows, are taken into consideration. In those situations, easy and fast reconfiguration and recalculation of timetable data is of central importance. This local and temporal rescheduling results in shifted departure and arrival times and sometimes even in modified stop patterns at intermediate stations of train runs. In order to generate reliable timetabling results it is a prerequisite that train-track assignments, as well as operational and commercial dependencies are taken into consideration. In order to refer to the right level of detail for modelling track infrastructure and train dynamics in the computer aided planning process we present a generic model that we call Track-Choice FPESP (TCFPESP), as it implements suitable extensions of the established PESP-model. We show, how the service intention (the data structure for timetable specification) together with resource capacity information entered into a standard timetabling tool like Viriato can be utilized in order to configure the TCFPESP model. In addition, we are able to calculate quantitative performance measures for assessing timetable quality aspects. In order to achieve this we present a method for evaluating travel times based on passenger routings and a method for evaluating timetable robustness based on max-plus algebra. This approach supports the planner to generate integrated periodic timetable solutions in iterative development cycles and taking into account intervals for local maintenance work

Efficient timetable stability analysis using a graph contraction procedure

Train density on the Swiss rail network has increased significantly in recent years. This demands much more from the stability of the system, especially in combination with single-track corridors. For railroad companies, it is therefore becoming increasingly important to optimize the transport network for stability in order to be able to offer the demanded service as reliably as possible on the existing infrastructure. An approach to numerical stability evaluation of timed discrete event systems has been developed to support planners in testing the timetable for operational stability. In this approach, the traffic system under consideration is modeled as a network with all relevant timetable events and links. The system modelled in this way can be examined for its behavior in the event of a possible disruption using methods from max-plus algebra. The typical computation time of an evaluation procedure takes more than 65 minutes for a signifcant partition of the line network. This is far too high for integration into a practical optimization procedure. In this paper we present a contraction procedure added to the existing evaluation framework, and thus reduce the computation time by more than 90% without compromising the result quality

Evaluation of the delay management potential on a macroscopic level

In general, macroscopic models in delay management allow for the optimization of large networks with reasonable computational effort. The main limitations here arise from the aggregated consideration of the infrastructure. In this paper, an evaluation of potential application of macroscopic models for delay management through a real case study is discussed. A macroscopic model is built by applying first a micro-macro transformation on a calibrated microscopic model, to provide an exact calculation of minimum running times and headways. On this macroscopic model, two disruption scenarios are analyzed and solved by using Event Activity Networks, to show the potential benefits and the limitations of delay management. The case study is based on a real railway infrastructure in Switzerland, and it is implemented in LinTim, an opensource software, which allows for an integrated development of both the macroscopic scenario and the delay management solutions