Estimating obsolescence risk from demand data - a case study

In this paper obsolescence of service parts is analyzed in a practical environment. Basedon the analysis, we propose a method that can be used to estimate the risk of obsolescenceof service parts. The method distinguishes groups of service parts. For these groups, therisk of obsolescence is estimated using the behavior of similar groups of service parts inthe past. The method uses demand data as main information source, and can therefore beapplied without the use of an expert's opinion. We will give numerical values for the risk ofobsolescence obtained with the method, and the e®ects of these values on inventory controlwill be examined.inventory;forecasting;obsolescence;spare parts

Finding optimal policies in the (S - 1, S ) lost sales inventory model with multiple demand classes

This paper examines the algorithms proposed in the literature forfinding good critical level policies in the (S-1,S) lost salesinventory model with multiple demand classes. Our main result isthat we establish guaranteed optimality for two of thesealgorithms. This result is extended to different resupplyassumptions, such as a single server queue. As a corollary, weprovide an alternative proof of the optimality of critical levelpolicies among the class of all policies.inventory;customer differentiation;multiple demand classes;rationing lost sales;stochastic dynamic programming

Risk-based stock decisions for projects

In this report we discuss a model that can be used to determine stocking levels using thedata that comes forward from a Shell RCM analysis and the dataavailable in E-SPIR. The model is appropriate to determine stockquantities for parts that are used in redundancy situations, andfor parts that are used in different pieces of equipment withdifferent downtime costs. Estimating the annual production lossusing the model consists of a number of steps. First, we need todetermine which spares are used for the repairs of which failuremodes. In the second step, we estimate the average waiting timefor spares as a function of the number of spares stocked. In thethird step, the annual downtime costs are determined. We combinethe downtime costs with the holding costs to determine the optimalnumber of parts to stock.

NET WORKING: Work Patterns and Workforce Policies for the New Media Industry

This report, based on a study of a group of highly accomplished professionals in New York City, is one of the first to take up labor market issues in the new media industry. It describes the challenges faced by professionals and employers alike in this important and dynamic sector, and identifies strategies for success in a project oriented environment with highly complex skill demands and rapidly changing technology. Our findings suggest three central issues

Labour Market Segmentation Revisited: A Study of the Dutch Call Centre Sector

Employment in the call centre sector in the Netherlands, similar to the trend in other European countries, is expanding greatly. In 2001, Datamonitor (2002) estimated that 1,266 call centres were operating in the Netherlands. This number is expected to have risen to roughly 2,000 in 2006. An estimated 188,000 people work in this sector at the moment, representing 2.5% of the entire working population in the Netherlands. This represents the highest percentage in Europe with the exception of Ireland. The call centre workforce is employed by in-house and subcontractor call centres. In-house call centres are part of the firm for which they handle customer contacts, whereas subcontractor call centres, which provide customer contact services for other firms or institutions. The call centre sector features a large number of employees working in so-called atypical employment contracts, in particular ‘agents’ who handle the actual customer contacts (De Grip, Hoevenberg & Willems, 1997). Agents are often hired into temporary appointments, part-time contracts, irregular shifts, stand-by contracts, et cetera. The use of such atypical contracts is closely related to the great need for flexibility in the deployment of staff (Kalleberg, 2000). Such workforce flexibility is necessary in order to negotiate peaks and valleys in call volumes. In addition, many call centres prioritize on cost reduction, and this approach constrains investment in personnel. Call centres are therefore often classified as ‘electronic sweatshops’ offering only ‘dead-end jobs’ (Taylor, et al., 2002; Deery & Kinnie, 2004).The labour market for call centre agents could thus be characterised as a ‘secondary labour market’ of insecure, poorly paid jobs without any career opportunities (see e.g. Dekker, De Grip & Heijke, 2002). However, the call centre sector is heterogeneous with respect to employment conditions. For example, agents who work in in-house call centres have better employment conditions than their counterparts in subcontractor call centres. The Dutch industrial relations system offers one explanation for this difference. Agents working in in-house call centres have protections defined by the collective labour agreement (CLA) of the firm the call centre agents work in. In contrast, the subcontractor call centres did not have any comparable protections or their own CLA until 2003. The establishment of a CLA that covers agents employed in Dutch subcontractor call centres in 2003 is a unique phenomenon in the European call centre market (Roland, 2000b).The difference in working conditions between in-house and subcontractor call centres raises the following research question addressed in this paper: To what extent is the labour market for call centre agents a dual labour market, with a secondary segment in the subcontractor call centres, and a primary segment in the form of a ‘professional labour market’ in the in-house call centres?To answer this question, we analyze survey data collected from a national survey of call centre managers in the Netherlands. Moreover, we investigate whether the aforementioned need for workforce flexibility may provide an explanation for the labour market segmentation in the call centre sector and if this segmentation is embedded in Dutch industrial relations. We begin with a brief overview of labour market segmentation theory. Next, we describe the dataset, and provide some brief background about the Dutch call centre sector and its workforce. Then, we investigate the differences between employment conditions in in-house and subcontractor call centres, to determine whether there is a segmented labour markets. Finally, we assess the influence of industrial relations in the call centre sector, and determine whether these reflect the labour market segmentation.education, training and the labour market;

Scale and conservation planning in the real world

Conservation planning is carried out on a variety of geopolitical and biogeographical scales. Whereas considerable consensus is emerging about the most appropriate procedures for identifying conservation areas, the spatial implications of conducting conservation planning at divergent scales have received little attention. Here we explore the consequences of planning at different geopolitical scales, using a database of the mammalian fauna from the Northern Provinces of South Africa. The conservation network resulting from treating the region as one unit is compared with networks generated separately for the provinces nested in that region. These outcomes are evaluated in terms of (i) their land use efficiencies, (ii) their spatial overlap, and (iii) the impact of algorithm attributes. Although land use efficiencies are greater on broader scales, on average the spatial congruence between the broad-scale regional network and fine-scale provincial networks was less than 14%. Algorithms using different selection rules fail to improve this disturbing outcome. Consequently, scale has an overwhelming influence on areas identified as conservation networks in geopolitical units. This should be recognized in conservation planning