Reliability of evaluations for the choice of system solutions at the example of automated order-picking systems for bagged goods

There is a steadily increasing pressure on cost-savings and productivity growth in sectors of order-picking such that the wish for rationalization by automation is rising. Special problems are faced trying to automatize handling operations of order-picking articles packed in bags. The mechanical properties of the objects and their hard-to-predict shape and position represent obstacles and are complicating handling operations. A systematic approach in system design is required. This article deals with the properties of such products under aspects of difficulties arising in automated handling and points out a useful system development methodology.

Metaheuristics for the Order Batching Problem in Manual Order Picking Systems

In manual order picking systems, order pickers walk or drive through a distribution warehouse in order to collect items which are requested by (internal or external) customers. In order to perform these operations efficiently, it is usually required that customer orders are combined into (more substantial) picking orders of limited size. The Order Batching Problem considered in this paper deals with the question of how a given set of customer orders should be combined such that the total length of all tours is minimized which are necessary to collect all items. The authors introduce two metaheuristic approaches for the solution of this problem: the first one is based on Iterated Local Search; the second on Ant Colony Optimization. In a series of extensive numerical experiments, the newly developed approaches are benchmarked against classic solution methods. It is demonstrated that the proposed methods are not only superior to existing methods but provide solutions which may allow distribution warehouses to be operated significantly more efficiently.

Comparison of performance measurement-systems used for order-picking

In consequence of rapidly changing market demands companies are permanently encouraged to review their own processes and structures and to modify them. Being one of these developments, order-picking is involved as part of an intra-logistics system. But to take appropriate actions, system performance and system costs have to be measured permanently. Concerning this the use of performance measurement-systems as further development of traditional systems of key figures is suitable. In this paper various performance measurement-systems are compared and their suitability for an implementation in order-picking systems is estimated. On the basis of the result of the evaluation a first concept of a performance measurement-system for order-picking will be developed by using typical key figures that are mentioned in academic literature. Finally, hints for a necessary detailed implementation and evaluation in practice will be given.

Youth Work and Schools in ‘Full-day’ education systems: International Comparison of Links between Formal and Non-formal Education

In this article I will outline the methodological approach of a non-empirical comparative research project which I began in 2003. The project is situated in the context of the research training group “Youth Welfare in Transition” at the universities of Bielefeld and Dortmund, funded by the German Research Council (Deutsche Forschungsgemeinschaft). In that context I have organised an international conference about the modes of cooperation between school and youth work agencies with colleagues from Canada, France, Finland, Italy, Japan, the Netherlands, Russia, Switzerland, the United Kingdom, the United States, Israel, and Germany. Meeting in Bielefeld from the 9th to the 11th of October 2003, we compared the respective national arrangements of formal and non-formal education (www.uni-bielefeld.de/paedagogik/agn/ag8/Ganztagsbildung.html). This note is based on the scheme of comparison which was given to the contributors in order to help them preparing their presentations. At the moment the scheme is nearing completed with significant data prepared by the contributors/authors (see Otto/Coelen 2004), supplemented with data from research works published in German and English. The next step will be to set up an empirical project about the relationships between schools and youth work agencies in three European countries (probably France, Finland and the Netherlands).

Social Work and a New Social Order - Challenging Neo-liberalism's Erosion of Solidarity

The world in which social work operates today is a very different world from that in which most of us took their social work training, and the changes we are facing are profound. This paper argues that these changes are not merely a regime change in social policy but that they are essentially about a re-ordering of social relationships and attempt to model them on neo-liberal ideas. In view of these pressures it is understandable that social workers often try to ignore those changes and withdraw into a private world of therapeutic relationships in which the methods they trained in are made to be still valid, or they simply go along with new service delivery designs without asking too many questions. Both reactions fail to question what the "social" can still mean in the light of these changes and how social workers can fulfil their mandate to be responsible for the social dimension of public life. Nothing less than a head-on challenge of the basic presuppositions of neo-liberalism (Willke 2003) and their manifold applications to social service delivery systems will thereby suffice.

Technical throughput of material flow systems required to achieve design flow – determined by simulation with aniteration algorithm

This article deals with complex material flow systems and series connections of conveyor and op-erating elements. These can be characterised by a specific availability. The thus resultant overall availabil-ity of necessary “technical throughput” of the individual elements for the achievement of a specified throughput. When the conveyor and operating elements are subjected to a stochastic distribution, the interposition of buffers is necessary but these can also lead to a reduction of the necessary throughput due faults. The system behaviour of complex installations can only be investigated by simulation. The parame-ter changes required in order to achieve specific target values can also be determined by simulation runs in iteration loops.

Revenue Management in Make-To-Order Manufacturing: Case Study of Capacity Control at ThyssenKrupp VDM

While revenue management (RM) is traditionally considered a tool of service operations, RM shows considerable potential for application in manufacturing operations. The typical challenges in make-to-order manufacturing are fixed manufacturing capacities and a great variety in offered products, going along with pronounced fluctuations in demand and profitability. Since Harris and Pinder in the mid-90s, numerous papers have furthered the understanding of RM theory in this environment. Nevertheless, results to be expected from applying the developed methods to a practical industry setting have yet to be reported. To this end, this paper investigates a possible application of RM at ThyssenKrupp VDM, leading to considerable improvements in several areas.

Hands-Free Navigation in Immersive Environments for the Evaluation of the Effectiveness of Indoor Navigation Systems

While navigation systems for cars are in widespread use, only recently, indoor navigation systems based on smartphone apps became technically feasible. Hence tools in order to plan and evaluate particular designs of information provision are needed. Since tests in real infrastructures are costly and environmental conditions cannot be held constant, one must resort to virtual infrastructures. This paper presents the development of an environment for the support of the design of indoor navigation systems whose center piece consists in a hands-free navigation method using the Microsoft Kinect in the four-sided Definitely Affordable Virtual Environment (DAVE). Navigation controls using the user's gestures and postures as the input to the controls are designed and implemented. The installation of expensive and bulky hardware like treadmills is avoided while still giving the user a good impression of the distance she has traveled in virtual space. An advantage in comparison to approaches using a head mounted display is that the DAVE allows the users to interact with their smartphone. Thus the effects of different indoor navigation systems can be evaluated already in the planning phase using the resulting system

Learning Curves of Temporary Workers in Manual Order Picking Activities

Person-to-stock order picking is highly flexible and requires minimal investment costs in comparison to automated picking solutions. For these reasons, tradi-tional picking is widespread in distribution and production logistics. Due to its typically large proportion of manual activities, picking causes the highest operative personnel costs of all intralogistics process. The required personnel capacity in picking varies short- and mid-term due to capacity requirement fluctuations. These dynamics are often balanced by employing minimal permanent staff and using seasonal help when needed. The resulting high personnel fluctuation necessitates the frequent training of new pickers, which, in combination with in-creasingly complex work contents, highlights the im-portance of learning processes in picking. In industrial settings, learning is often quantified based on diminishing processing time and cost requirements with increasing experience. The best-known industrial learning curve models include those from Wright, de Jong, Baloff and Crossman, which are typically applied to the learning effects of an entire work crew rather than of individuals. These models have been validated in largely static work environments with homogeneous work contents. Little is known of learning effects in picking systems. Here, work contents are heterogeneous and individual work strategies vary among employees. A mix of temporary and steady employees with varying degrees of experience necessitates the observation of individual learning curves. In this paper, the individual picking performance development of temporary employees is analyzed and compared to that of steady employees in the same working environment.

A Fast Platform for Interactive E-Learning Systems

Modern e-learning systems represent a special type of web information systems. By definition, information systems are special computerized systems used to perform data operations by multiple users simultaneously. Each active user consumes an amount of hardware resources. A shortage of hardware resources can be caused by growing number of simultaneous users. Such situation can result in overall malfunctioning or slowed-down system. In order to avoid this problem, the underlying hardware system gets usually continuously upgraded. These upgrades, typically accompanied with various software updates, usually result in a temporarily increased amount of available resources. This work deals with the problem in a different way by proposing an implementation of a web e-learning system with a modified software architecture reducing resource usage of the server part to the bare minimum. In order to implement a full-scale e-learning system that could be used as a substitute to a conventional web e-learning system, a Rich Internet Application framework was used as basis. The technology allowed implementation of advanced interactivity features and provided an easy transfer of a substantial part of the application logic from server to clients. In combination with a special server application, the server part of the new system is able to run with a reasonable performance on a hardware with very limited computing resources.

Performance Availability and Anticipatory Change Planning of Intralogistics Systems: A Simulation-Based Approach

In recent years, the ability to respond to real time changes in operations and reconfigurability in equipment are likely to become essential characteristics for next generation intralogistics systems as well as the level of automation, cost effectiveness and maximum throughput. In order to cope with turbulences and the increasing level of dynamic conditions, future intralogistics systems have to feature short reaction times, high flexibility in processes and the ability to adapt to frequent changes. The increasing autonomy and complexity in processes of today’s intralogistics systems requires new and innovative management approaches, which allow a fast response to (un)anticipated events and adaptation to changing environment in order to reduce the negative consequences of these events. The ability of a system to respond effectively a disruption depends more on the decisions taken before the event than those taken during or after. In this context, anticipatory change planning can be a usable approach for managers to make contingency plans for intralogistics systems to deal with the rapidly changing marketplace. This paper proposes a simulation-based decision making framework for the anticipatory change planning of intralogistics systems. This approach includes the quantitative assessments based on the simulation in defined scenarios as well as the analysis of performance availability that combines the flexibility corridors of different performance dimensions. The implementation of the approach is illustrated on a new intralogistics technology called the Cellular Transport System.

Advanced luminance control and black offset correction for multi-projector display systems

In order to display a homogeneous image using multiple projectors, differences in the projected intensities must be compensated. In this paper, we present novel approaches to combine and extend existing techniques for edge blending and luminance harmonization to achieve a detailed luminance control. Furthermore, we apply techniques for improving the contrast ratio of multi-segmented displays also to the black offset correction. We also present a simple scheme to involve the displayed context in the correction process to dynamically improve the contrast in brighter images. In addition, we present a metric to evaluate the different methods and their influence on the visual quality.