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Article
Publication date: 1 March 2013

Christoph H. Glock and Michael G. Broens

This paper analyzes how German municipalities organize their purchasing activities. It aims to identify patterns in the structure of the purchasing function and to study…

Abstract

This paper analyzes how German municipalities organize their purchasing activities. It aims to identify patterns in the structure of the purchasing function and to study how the size of the municipality influences the design of its purchasing organization. Therefore, an analytical framework based on contingency and organization theory is developed and results of an empirical study are presented. The results indicate that German municipalities use a medium level of centralization and specialization in organizing their purchasing activities, but that the purchasing process is highly formalized and represented on high hierarchical levels in many cases. As to the relationship between the size of a municipality and the structure of its purchasing function, the study indicates that size, measured by the number of inhabitants, the number of employees and purchasing volume influences the structural variables in various ways.

Details

Journal of Public Procurement, vol. 13 no. 1
Type: Research Article
ISSN: 1535-0118

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Article
Publication date: 14 August 2017

Torsten Franzke, Eric H. Grosse, Christoph H. Glock and Ralf Elbert

Order picking is one of the most costly logistics processes in warehouses. As a result, the optimization of order picking processes has received an increased attention in…

Abstract

Purpose

Order picking is one of the most costly logistics processes in warehouses. As a result, the optimization of order picking processes has received an increased attention in recent years. One potential source for improving order picking is the reduction of picker blocking. The purpose of this paper is to investigate picker blocking under different storage assignment and order picker-route combinations and evaluate its effects on the performance of manual order picking processes.

Design/methodology/approach

This study develops an agent-based simulation model (ABS) for order picking in a rectangular warehouse. By employing an ABS, we are able to study the behaviour of individual order pickers and their interactions with the environment.

Findings

The simulation model determines shortest mean throughput times when the same routing policy is assigned to all order pickers. In addition, it evaluates the efficiency of alternative routing policies–storage assignment combinations.

Research limitations/implications

The paper implies that ABS is well-suited for further investigations in the field of picker blocking, for example, with respect to the individual behaviour of agents.

Practical implications

Based on the results of this paper, warehouse managers can choose an appropriate routing policy that best matches their storage assignment policy and the number of order pickers employed.

Originality/value

This paper is the first to comprehensively study the effects of different combinations of order picker routing and storage assignment policies on the occurrence of picker blocking.

Details

The International Journal of Logistics Management, vol. 28 no. 3
Type: Research Article
ISSN: 0957-4093

Keywords

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Article
Publication date: 9 November 2015

Christoph H Glock and Taebok Kim

This paper studies a supply chain consisting of multiple suppliers and a single buyer. It considers the case where a set of heterogeneous trucks is used for transporting…

Abstract

Purpose

This paper studies a supply chain consisting of multiple suppliers and a single buyer. It considers the case where a set of heterogeneous trucks is used for transporting products, and develops a mathematical model that coordinates the supply chain. The purpose of this paper is to minimise the costs of producing and delivering a product as well as carbon emissions resulting from transportation. In addition, the authors analyse how imposing a tax on carbon emissions impacts the delivery of products from the suppliers to the buyer.

Design/methodology/approach

It is assumed that heterogeneous vehicles are used for transporting products, which have different performance and cost attributes. A mathematical model that considers both operating costs and carbon emissions from transportation is developed. The impact of vehicle attributes on lot sizing and routing decisions is studied with the help of numerical examples and a sensitivity analysis.

Findings

The analysis shows that considering carbon emissions in coordinating a supply chain leads to changes in the routing of vehicles. It is further shown that if carbon emissions lead to costs, routes are changed in such a way that vehicles travel long distances empty or with a low vehicle load to reduce fuel consumption and therewith emissions.

Research limitations/implications

Several areas for future work are highlighted. The study of alternative supply chain structures, for example structures which include logistics service providers, or the investigation of different functional relationships between vehicle load and emission generation offer possibilities for extending the model.

Originality/value

The paper is one of the first to study the use of heterogeneous vehicles in an inventory model of a supply chain, and one of the few supply chain inventory models that consider ecological aspects.

Details

The International Journal of Logistics Management, vol. 26 no. 3
Type: Research Article
ISSN: 0957-4093

Keywords

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Article
Publication date: 2 November 2012

Christoph H. Glock, Mohamad Y. Jaber and Cory Searcy

The purpose of this paper is to present a mathematical model that illustrates the trade‐offs between sustainability, demand, costs, and profit in a supply chain with a…

Abstract

Purpose

The purpose of this paper is to present a mathematical model that illustrates the trade‐offs between sustainability, demand, costs, and profit in a supply chain with a single supplier and a single manufacturer.

Design/methodology/approach

It is assumed that a single product is produced and sold on a market where demand is sensitive to price and quality. Sustainability is treated as a quality attribute and is measured in terms of the levels of scrap and emissions generated in the supply chain. It is assumed that the emissions and scrap can be controlled by varying production rates or by investing in production processes. The impact of cooperative and non‐cooperative behaviour between the supplier and the manufacturer is explored. Numerical studies are used to illustrate the behaviour of the model.

Findings

The analysis shows that the supplier and the manufacturer can attract additional customers by controlling scrap and emissions. The behaviour of the supplier and the manufacturer are dictated by the decision criteria, such as changes in the level of sustainability, used by customers to evaluate the product. It is shown that the profit of the system is higher and that the level of quality is lower in the case of cooperation than in the case of non‐cooperation.

Research limitations/implications

Several areas for future work are highlighted. The study of alternative demand functions, linking sustainability to a monetary component, including additional players, and incorporating additional sustainability indicators all offer possibilities for extending the model.

Originality/value

There is an identified need for analytical models that consider sustainability in the supply chain. The results are especially important for companies operating in markets where customers perceive the sustainability of a product as a quality criterion.

Details

The International Journal of Logistics Management, vol. 23 no. 3
Type: Research Article
ISSN: 0957-4093

Keywords

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Article
Publication date: 19 July 2013

Eric H. Grosse and Christoph H. Glock

The purpose of this paper is to study the prevalence of human learning in the order picking process in an experimental study. Further, it aims to compare alternative…

Abstract

Purpose

The purpose of this paper is to study the prevalence of human learning in the order picking process in an experimental study. Further, it aims to compare alternative learning curves from the literature and to assess which learning curves are most suitable to describe learning in order picking.

Design/methodology/approach

An experimental study was conducted at a manufacturer of household products. Empirical data was collected in the order picking process, and six learning curves were fitted to the data in a regression analysis.

Findings

It is shown that learning occurs in order picking, and that the learning curves of Wright, De Jong and Dar‐El et al. and the three‐parameter hyperbolic model are suitable to approximate the learning effect. The Stanford B model and the time constant model led to unrealistic results.

Practical implications

The results imply that human learning should be considered in planning the order picking process, for example in designing the layout of the warehouse or in setting up work schedules.

Originality/value

The paper is the first to study learning effects in order picking systems, and one of the few papers that use empirical data from an industrial application to study learning effects.

Details

Journal of Manufacturing Technology Management, vol. 24 no. 6
Type: Research Article
ISSN: 1741-038X

Keywords

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Article
Publication date: 15 July 2014

Christoph H. Glock and Mohamad Y. Jaber

– The purpose of the paper is to develop a mathematical model that describes group learning processes with and without worker turnover.

Abstract

Purpose

The purpose of the paper is to develop a mathematical model that describes group learning processes with and without worker turnover.

Design/methodology/approach

Based on an extensive literature review, fundamental characteristics of group learning processes are first identified and then incorporated into a group learning curve (GLC). The developed GLC is then validated by fitting to empirical data.

Findings

The results show that the behaviour of the developed model is in conformance with the characteristics identified in the literature. A comparison with two other learning curves that have frequently been discussed in the literature shows that the GLC developed in this paper is a good mathematical representation of group learning processes.

Practical implications

The model developed in this paper enables practitioners to predict performance improvement in groups.

Originality/value

The paper is one of the first to propose a mathematical formulation of a GLC.

Details

Journal of Modelling in Management, vol. 9 no. 2
Type: Research Article
ISSN: 1746-5664

Keywords

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