# Florian Jaehn's research while affiliated with Helmut Schmidt University / University of the Federal Armed Forces Hamburg and other places

## Publications (61)

Article
The advent of automated and semiautomated driving technologies is prompting a reevaluation of the benefits of truck platooning. Whereas the effect of truck platooning on fuel costs is relatively well studied, automated driving enables further cost reductions in the form of labor savings that has, heretofore, been sparingly investigated. The degree...
Article
When boarding an aircraft, it is often assumed that minimizing the total boarding time meets economic objectives and passenger satisfaction. However, there are indications that not only the total boarding time should be considered in order to satisfy passengers. In “Air passenger preferences: an international comparison affects boarding theory,” a...
Article
Sometimes measurements taken to increase resource efficiency do not reach the estimated magnitude, as part of the reduction vanishes due to the reaction of entities to the changed environment. This so-called rebound effect is intensively discussed in the energy sector literature. Surprisingly, little is found for transportation, and the question ar...
Article
Full-text available
We consider the $$\mathscr {NP}$$-hard twin robot scheduling problem, which was introduced by Erdoğan et al. (Naval Res Logist (NRL) 61(2):119–130, 2014). Here, two moving robots positioned at the opposite ends of a rail have to perform automated storage and retrieval jobs at given positions along the gantry rail with a non-crossing constraint. The...
Article
Full-text available
In fields like transport or materials sourcing, it is common industrial practice nowadays to contract several partners for the fulfilment of similar sets of tasks. A typical approach is to include quotes to the contracts that specify which portion of the total volume should be given to each partner. In this study, which is inspired by a real-world...
Article
Full-text available
We present a test data generator that can be used for simulating processes of cranes handling containers. The concepts originate from container storage areas at seaports, but the generator can also be used for other applications, particularly for train terminals. A key aspect is that one or multiple cranes handle containers, that is, they store con...
Article
The paper industry supply chain is highly complex and consists of many processes and planning tasks. It starts with the collection of raw wood and ends up in different paper products from paperboard to high class art papers. Managing the supply chain is difficult and the permanently changing business environment constantly brings new challenges. Th...
Chapter
Bei Open Shop-Problemen gelten ähnliche Voraussetzungen wie bei Job Shops und Flow Shops. Insbesondere muss jeder Auftrag auf jeder Maschine ausgeführt werden. Allerdings ist die Reihenfolge der Maschinen, die ein Auftrag durchläuft, frei wählbar. Ein Beispiel für einen Open Shop ist im Krankenhausmanagement zu finden.
Book
Planen von Abläufen ist zentraler Bestandteil unternehmerischen Handelns in Produktion, Logistik, Marketing und Personal oder von Anwendungen im Maschinenbau oder der Informatik. Ziel dieses Buches ist es, gängige Ablaufplanungsprobleme zu kategorisieren und für diese Lösungsansätze zu präsentieren, so dass das in der Praxis vorhandene Verbesserung...
Chapter
Im Gegensatz zu den parallelen Maschinenmodellen gehen wir nun davon aus, dass jeder Auftrag auf jeder Maschine ausgeführt werden muss. Die Maschinen sind also unterschiedlich in ihren Aufgaben der Produktherstellung. Tritt der Fall ein, dass einzelne Aufträge bestimmte Maschinen nicht besuchen brauchen, so lässt sich dies mit einer Bearbeitungszei...
Chapter
Einige der in der Ablaufplanung typischen Bezeichnungen haben wir bereits kennengelernt. Diese werden im Folgenden ergänzt und zu einer simplen, aber mächtigen Beschreibung von Ablaufplanungsproblemen genutzt. Fassen wir zunächst einmal grundlegende Bezeichnungen sowie die Charakterisierung eines Auftrags zusammen. Diese sind in Tabelle 2.1 dargest...
Chapter
Bei den Problemstellungen Pm||γ muss jeder Auftrag auf einer beliebigen Maschine von insgesamt m identischen Maschinen ausgeführt werden.
Chapter
In einem Job Shop gelten bis auf einen Unterschied die gleichen Voraussetzungen wie in einem Flow Shop. Jeder Auftrag hat eine individuelle, fest vorgegebene Reihenfolge, in der er die Maschinen durchlaufen muss. Zwei Aufträge können somit unterschiedliche Reihenfolgen haben. Ein Flow Shop ist also ein spezieller Job Shop, bei dem die Reihenfolge d...
Chapter
Fassen wir zunächst einmal die Ablaufplanungsprobleme mit einer Maschine zusammen, die wir bereits kennengelernt haben. Dazu sei angemerkt, dass das Sortieren von n Aufträgen mit einem Zeitaufwand von O(n log n) machbar ist.
Chapter
Die in der Theorie betrachteten und mit der Dreifeldnotation dargestellten Fragestellungen können als Grundform der in der Praxis vorkommenden Ablaufplanungsprobleme aufgefasst werden. Meist erweisen sich die praktischen Fragestellungen als deutlich weitreichender und entsprechen somit selten den idealtypischen Modellen.
Chapter
In den Beispielen 1.1 und 1.3 haben wir die Probleme 1|| Lmax und 1|| ∑ Uj kennengelernt. In den Beispielen wurden auch Probleminstanzen (also konkrete Zahlenwerte für die Problemstellung) genannt. Wir konnten zeigen, dass sich die Problemstellungen mittels der Lieferterminregel bzw. dem Algorithmus von Moore nicht nur für die genannten Instanzen l...
Article
Full-text available
This paper deals with crane scheduling in a block of a container terminal equipped with two crossover cranes. We concentrate on the situation when all requests in this block refer to the seaside. This seaside peak time occurs when a container ship is berthed and has to be served as quickly as possible because berthing time is a major cost driver fo...
Article
Full-text available
In this paper we study the problem of delivering finished vehicles from a logistics yard to dealer locations at which they are sold. The requests for cars arrive dynamically and are not announced in advance to the logistics provider who is granted a certain time-span until which a delivery has to be fulfilled. In a real-world setting, the underlyin...
Article
The topic of airplane boarding is receiving increasing attention in practice and in the scientific literature. Shorter boarding times can reduce the time an airplane spends at the gate (the airplane turn-around time), resulting in annual cost savings of several hundred thousand dollars per airplane. Although several researchers have analyzed the bo...
Article
We consider a scheduling problem for two gantry cranes moving on the same rails at a single storage block. Containers originating at the seaside have to be stored in the block and containers that are already stored in the storage area at the beginning of the planning horizon have to be delivered to the landside handover point within given time wind...
Article
Full-text available
In this paper, we study the railcar retrieval problem (RRT) in which specified numbers of certain types of railcars must be withdrawn from the storage tracks of a flat yard. This task arises as part of daily operations of railcar maintenance workshops. The objective is to minimize the total cost of the shunting operations. We describe the RRT forma...
Article
In this paper we study the classical scheduling problem of minimizing the total weighted completion time on a single machine with the constraint that one specific job must be scheduled at a specified position. We give dynamic programs with pseudo-polynomial running time, and a fully polynomial-time approximation scheme (FPTAS).
Article
This paper addresses one-machine scheduling with maintenance restrictions. A maintenance operation is position dependent in a sequence of normal jobs if the maintenance has to be performed after at most some defined number of job changes on the machine. We show that several problems with objective functions Cmax and Lmax are still solvable in polyn...
Article
We consider the problem of scheduling two identical rail mounted gantry cranes (twin cranes) working within a single storage area (block) at a seaport. The cranes, referred to as seaside crane and landside crane, cannot pass each other. Our focus is on peak times, where the minimization of dwell times of vessels at the berth is typically the major...
Article
Full-text available
A hub-and-spoke railway system is an efficient way of handling freight transport by land. A modern rail–rail train yard consists of huge gantry cranes that move the containers between the trains. In this context, we consider a rail–rail transshipment yard scheduling problem (TYSP) where the containers arrive to the hub and need to be placed on a tr...
Article
Full-text available
We consider the problem of assigning flights to airport gates. We examine the general case in which an aircraft serving a flight may be assigned to different gates for arrival, parking, and departure processing. The objectives can be divided into deterministic and stochastic goals. The former include maximization of the total assignment preference...
Article
Full-text available
In time-dependent scheduling, various processing time functions are studied, yet absolute value functions have surprisingly been omitted from the discussion. Such a processing time function increases linearly with a job’s discrepancy from its ideal midtime. The objective is to find a schedule that minimizes the makespan, introducing the discrepancy...
Article
We consider a problem arising in international rail freight transport. At a shunting yard, inbound trains are taken apart by decoupling freight cars, which are then sent through a system of tracks and switching points to form new outbound trains. Each freight car has a designated outbound train, but each outbound train might consist of freight cars...
Article
The field of "Sustainable Operations" and the term itself have arisen only in the last ten to twenty years in the context of sustainable development. Even though the term is frequently used in practice and research, it has hardly been characterized and defined precisely in the literature so far. For reasons of clarity and unambiguity, we present te...
Article
This paper deals with crane scheduling in a block of a container terminal equipped with twin cranes when repositioning moves turn out necessary. While one crane is working on a given schedule we aim to anticipate as many repositioning jobs as possible using the second crane without disturbing the first crane. In seaport operations, this situation i...
Article
The field of “Sustainable Operations” and the term itself have arisen only in the last ten to twenty years in the context of sustainable development. Even though the term is frequently used in practice and research, it has hardly been characterized and defined precisely in the literature so far. For reasons of clarity and unambiguity, we present te...
Article
We consider an operational process at shunting yards, where freight cars are disassembled and reassembled via a system of tracks and switches to form outbound trains with no restriction on the order of the freight cars. Given are due dates for each outbound train and priority values for its freight cars. Furthermore, the composition and the process...
Article
The time required to board an airplane directly influences an airplane’s turn-around time, i.e., the time that the airplane requires at the gate between two flights. Thus, the turn-around time can be reduced by using efficient boarding methods and such actions may also result in cost savings. The main contribution of this paper is fourfold. First,...
Article
In a traditional rail-freight hump yard, a huge number of freight cars are perpetually shunted to form outbound trains. In order to transport each car to its destination, the inbound trains are decoupled and disassembled into individual cars, which are then moved to one of several classification tracks where they are reassembled to form new outboun...
Article
We study a problem of scheduling products on the same facility, which is motivated by a car paint shop. Items of the same product are identical. Operations on the items are performed sequentially in batches, where each batch is a set of operations on the same product. Some of the produced items are of the required good quality and some items can be...
Chapter
Im Gegensatz zu den parallelen Maschinenmodellen gehen wir nun davon aus, dass jeder Auftrag auf jeder Maschine ausgeführt werden muss. Die Maschinen sind also unterschiedlich in ihren Aufgaben der Produktherstellung. Tritt der Fall ein, dass einzelne Aufträge bestimmte Maschinen nicht besuchen brauchen, so lässt sich dies mit einer Bearbeitungszei...
Chapter
In den Beispielen 1.1 und 1.3 haben wir die Probleme $$1||{{L}_{\max }}$$ und $$1||\sum{{{U}_{j}}}$$ kennengelernt. In den Beispielen wurden auch Probleminstanzen (also konkrete Zahlenwerte für die Problemstellung) genannt. Wir konnten zeigen, dass sich die Problemstellungen mittels der Lieferterminregel bzw. dem Algorithmus von Moore nicht nur für...
Chapter
Bei den Problemstellungen $$Pm||\gamma$$ muss jeder Auftrag auf einer beliebigen Maschine von insgesamt m identischen Maschinen ausgeführt werden. Sofern ein Auftrag geteilt wird und auf mehr als einer Maschine ausgeführt wird, was natürlich nur im Fall pmtn erlaubt ist, so können die Teilaufträge jedoch nicht zur gleichen Zeit bearbeitet werden. E...
Chapter
Einige der in der Ablaufplanung typischen Bezeichnungen haben wir bereits kennen gelernt. Diese werden im Folgenden ergänzt und zu einer simplen, aber dennoch äußerst mächtigen Beschreibung von Ablaufplanungsproblemen genutzt. Fassen wir zunächst einmal grundlegende Variablenbezeichnungen sowie die Charakterisierung eines Auftrags zusammen.
Chapter
Die in der Theorie betrachteten und mit der Dreifeldnotation dargestellten Fragestellungen können als Grundform der in der Praxis vorkommenden Ablaufplanungsprobleme aufgefasst werden. Meist erweisen sich die praktischen Fragestellungen als deutlich weitreichender und entsprechen somit selten den idealtypischen Modellen.
Chapter
Fassen wir zunächst einmal die Ablaufplanungsprobleme mit einer Maschine zusammen, die wir bereits kennengelernt haben. Dazu sei angemerkt, dass das Sortieren von n Aufträgen mit einem Zeitaufwand von O(n log n) machbar ist.
Chapter
In einem Job Shop gelten bis auf einen Unterschied die gleichen Voraussetzungen, wie in einem Flow Shop. Jeder Auftrag hat eine individuelle, fest vorgegebene Reihenfolge in der er die Maschinen durchlaufen muss. Zwei Aufträge können somit unterschiedliche Reihenfolgen haben.
Chapter
Bei Open Shop Problemen gelten ähnliche Voraussetzungen wie bei Job Shops und Flow Shops. Insbesondere muss jeder Auftrag auf jeder Maschine ausgeführt werden. Allerdings ist die Reihenfolge der Maschinen, die ein Auftrag durchläuft, frei wählbar. Ein Beispiel für ein Open Shop ist im Krankenhausmanagement zu finden.
Article
This paper considers the problem of clustering the vertices of a complete edge-weighted graph. The objective is to maximize the sum of the edge weights within the clusters (also called cliques). This so-called Clique Partitioning Problem (CPP) is NP-complete, and has several real-life applications such as groupings in flexible manufacturing systems...
Article
In spite of extraordinary support programs initiated by the European Union and other national authorities, the percentage of overall freight traffic moved by train is in steady decline. This development has occurred because the macroeconomic benefits of rail traffic, such as the relief of overloaded road networks and reduced environmental impacts,...
Article
The paper “Multistage Methods for Freight Train Classification” by Jacob et al. [Networks 57 (2011) 87–105] provides great insight into the theory and practice of sorting procedures at shunting yards. In Jacob et al. [Networks 57 (2011) 87–105] many relevant shunting situations (e.g., single or multiple inbound trains, single or multiple outbound t...
Article
This paper considers a decision problem as it arises in a rail–road transshipment yard when unloading a bundle of trains. The loading units, e.g. containers, arriving on trains and occasionally arriving on trucks have to be placed on storage lanes of limited capacity. Loading units are placed and removed keeping stacking and crane rail moves small....
Article
This paper focuses on single machine scheduling subject to inventory constraints. Jobs add or remove items to or from the inventory, respectively. Jobs that remove items cannot be processed if the required number of items is not available. We consider scheduling problems on a single machine where the objective is to minimize the total weighted comp...
Article
Full-text available
In a modern rail–rail transshipment yard huge gantry cranes transship containers between different freight trains, so that hub-and-spoke railway systems are enabled. In this context, we consider the transshipment yard scheduling problem (TYSP) where trains have to be assigned to bundles, which jointly enter and leave the yard. The objective is to m...
Article
Almost ever since freight has been transported via rail, shunting yards (also called classification or marshaling yards) are operated in order to separate freight trains and reassemble new trains. The efficient use of shunting yards has a deep impact on the efficiency and reliability of rail freight services. Thus, much research on shunting yards h...
Article
Full-text available
This paper considers the problem of assigning flights to airport gates. We examine the general case in which an aircraft serving a flight may be assigned to different gates for arrival and departure processing and for optional intermediate parking. Restrictions to this assignment include gate closures and shadow restrictions, i.e., the situation wh...
Article
We are glad to see the final version of this special issue of Decision Making in Manufacturing and Services (DMMS) on Optimization in Supply Chain Management take shape. It does not come as a surprise that we received a rather heterogeneous batch of submissions concerning different aspects of optimization focusing on applications in supply chain ma...
Article
This paper considers the problem of assigning flights to airport gates—a problem which is NP-hard in general. We focus on a special case in which the maximization of flight/gate preference scores is the only objective. We show that for a variable number of flights and gates, this problem is still NP-hard. For a fixed number of gates, we present a d...
Article
We consider a very general case of the facility layout problem, which allows incorporating various aspects appearing in real life applications. These aspects include loose requirements on facilities' footprints, each of which only needs to be of rectangular shape and can optionally be restricted concerning the surface area or the aspect ratio. Comp...
Article
This article considers the price history of CO2 allowances in the EU Emission Trading Scheme. Since European Emissions Trading started in 2005, the prices of allowances have varied between less than one and thirty Euro per ton of CO2. This previously unpredicted volatility and, more notably, a significant price crash in May 2005 led to the hypothes...
Article
This paper considers the problem of assigning flights to airport gates. We examine the general case in which an aircraft serving a flight may be assigned to different gates for arrival and departure processing and for optional intermediate parking. Restrictions to this assignment include gate closures and shadow restrictions, i.e., the situation in...
Article
This paper introduces models of robustness in flight gate assignments at airports. We briefly repeat the general flight gate assignment problem and disruptions occurring in airline scheduling. Recovery strategies and robust scheduling are surveyed as the main methods in disruption management. We present a non-robust flight gate assignment model and...
Article
Full-text available
We consider the problem of assigning flights to airport gates. We exam-ine the general case in which an aircraft serving a flight may be assigned to different gates for arrival and departure processing and for optional intermediate parking. Re-strictions to this assignment include gate closures and shadow restrictions, i. e. the situation where cer...

## Citations

... Given the latest developments in this field, this can also improve the modal and vehicle choice decisions 10 Examples of bounded rationality that influence vehicle purchase decisionmaking are brand preferences [170], social norms and status [171], confirmation bias [172], and emotional and affective decision making [173,174]. 11 Travel rebound effects refer to behavioral or systemic reactions that lead to a lesser reduction of mobility demand or its total energy consumption than what could be expected from technologies or measures that increase the efficiency [175]. Behavioral rebound effects reflect, for instance, an increased amount of mobility demand due to targeted information of information and communications technologies [31,176], and potentially increased mobility demand due to new mobility services like autonomous vehicles that could perform empty runs, make cars accessible to people that would otherwise not use them, and lead to relaxed travel time constraints [177,178]. ...
... Even though this metric measures the passenger's boarding time, it may be viewed as a health metric in that higher values of the time spent by a passenger in the aisle might increase his/her health risk due to exposure from other passengers walking or standing in the aisle who may be contagious and potentially have shed the virus prior to a later boarding passenger's arrival in a particular (potentially infectious) area. This metric has another advantage as an indication of customer satisfaction as passengers prefer their individual boarding times to be short [58]. ...
... e dynamic programming method is applied to determine the scheme of another robot with the noncrossing constraint. Jaehn and Wiehl [36] further extended the TRSP by considering the types of S/R requests and the makespan (d > 0), meanwhile designed the accurate algorithm and approximate algorithm to solve the problem. e construction of the problem is closer to the actual application scenarios. ...
... Our world consists of a variety of complex events and ongoing technical advancements, which give rise to the occurrence of permanent planning and coordinating activities. This motivates scheduling research to deal with the general allocation of resources over time to fulll a given set of tasks, eciently, cf. for instance [25], [72] and [102]. As a multifaceted research eld, scheduling applies to classical planning problems in manufacturing and logistics as well as to technical and non-technical assignment decisions in IT infrastructures, data analytics, controlling and marketing. ...
... Interest in researching reverse supply chains (RSCs) and reverse logistic (RLs) is growing, as indicated by large quantities of publications in the field. The literature especially review papers have split the field into two themes: specific aspects of RLs, such as modeling [1], RL planning [2], drivers [3], performance measures [4], and structure [5], and a general overview of RL [6,7]. Figure 1 shows the basic concept of RL. ...
... This, however, is counterbalanced by the larger distance gantries have to cover when moving along the length of a container of a bay (compared to the much shorter container width passed by the trolley). Given the crane speed specifications by Briskorn et al. (2019), for instance, the time difference for crane travel along both dimensions of a TEU container is less than 0.5 seconds. Compared to the much longer pickup and drop-off times, which according to Briskorn et al. (2019) range between 20 and 40 seconds, the time difference is thus negligible, and this assumption is often made in crane scheduling research (see Kellner & Boysen, 2015;Boysen et al., 2017;Ehleiter & Jaehn, 2018). ...
... The latter seeks to partition a graph into even-sized components while minimizing the number of edges. Figure 1 summarizes other problems that can be modeled as Balanced Partition, including: People Assignment [34], Routing [31], [35]- [38], Task Allocation [39], [40], File Placement [41], [42] and Scheduling [43]- [45]. We briefly describe them in the following lines. ...
... However, most of the studies assume a full passenger load and that passengers leave the airport terminal to enter the airplane through a jet bridge [2,[27][28][29][30][31][32]. Only one recent study assumes passengers take apron buses from the terminal to the airplane during the pandemic [5]. ...
... Jaehn et al. [25] studied the benefits of using the handshake area in the dual ASC system, the study showed that it is beneficial to allow ASCs to cooperate in this way, especially when there are no containers in the block, introduced the lower bound method and heuristic method to study whether this positive effect can be sustained. Kress et al. [26] studied the setting of a handshake area in the dual ASC system, proposed a dynamic programming algorithm, which can quickly and effectively solve this problem. ...
... Nils, B. et al. [3] provided a classification scheme for crane scheduling problems with crane interference, and in their classification scheme, any crane scheduling problem is described by three basic elements: the terminal layout (including the available cranes), the characteristics of container moving, and an objective to be followed. Ehleiter, A. et al. [4] introduced that by considering the number of cranes, the crane scheduling can be classified as one crane, twin cranes, and triple cranes scheduling problems. Additionally, the crane scheduling problems can also be classified by considering whether the cranes can crossover each other or not. ...