Study on Capacity, Change and Performance: Interim Report

In 2002 the chair of the Govnet, the OECD's Network on Governance and Capacity Building, asked the European Centre for Development Policy Management (ECDPM) in Maastricht, the Netherlands, to undertake a study of the capacity of organisations and groups of organisations, mainly in low-income countries, its development over time and its relationship to improved performance. The specific purposes of this study were twofold:to enhance understanding of the interrelationships amongst capacity, change and performance across a wide range of development experiences; andto provide general recommendations and tools to support the effectiveness of external interventions aimed at improving capacity and performance

Exploring applicability of the workload control concept

To be successful in companies, a production planning and control (PPC) concept should fit to the production environment. Essential elements of the concept should correspond with the characteristics of the production system. For classical concepts such as MRP these elements have become common sense. For example BOMexplosion and constant lead times make MRP known to perform best in environments with high material and low capacity complexity. For many other concepts the situation is less clear. In this paper the Workload Control (WLC) concept is considered for which the requirements for a successful application have never been investigated. A framework is proposed to explore the applicability of WLC in small- to medium-sized make-to-order (MTO) companies. It supports an initial consideration of WLC in the first phase of a PPC selection and implementation process. As a first step in developing the framework the inherent characteristics of the WLC concept and the relevant MTO production characteristics are identified. Confronting the indicators of the company characteristics with the WLC elements results in bestfit indications for the WLC concept. Contrarily to other PPC evaluation schemes the framework considers variability indicators besides averages. Use of this framework for a medium sized MTO company demonstrates its suitability in getting a systematic and quick impression of the applicability of WLC. Essential elements are treated and assessed.

Trellis-Based Equalization for Sparse ISI Channels Revisited

Sparse intersymbol-interference (ISI) channels are encountered in a variety of high-data-rate communication systems. Such channels have a large channel memory length, but only a small number of significant channel coefficients. In this paper, trellis-based equalization of sparse ISI channels is revisited. Due to the large channel memory length, the complexity of maximum-likelihood detection, e.g., by means of the Viterbi algorithm (VA), is normally prohibitive. In the first part of the paper, a unified framework based on factor graphs is presented for complexity reduction without loss of optimality. In this new context, two known reduced-complexity algorithms for sparse ISI channels are recapitulated: The multi-trellis VA (M-VA) and the parallel-trellis VA (P-VA). It is shown that the M-VA, although claimed, does not lead to a reduced computational complexity. The P-VA, on the other hand, leads to a significant complexity reduction, but can only be applied for a certain class of sparse channels. In the second part of the paper, a unified approach is investigated to tackle general sparse channels: It is shown that the use of a linear filter at the receiver renders the application of standard reduced-state trellis-based equalizer algorithms feasible, without significant loss of optimality. Numerical results verify the efficiency of the proposed receiver structure.Comment: To be presented at the 2005 IEEE Int. Symp. Inform. Theory (ISIT 2005), September 4-9, 2005, Adelaide, Australi

Analytical derivation of EXIT charts for simple block codes and for LDPC codes using information combining

Publication in the conference proceedings of EUSIPCO, Viena, Austria, 200

Statistical Characterization of Temperature Patterns in Anisotropic Cosmologies

We consider the issue of characterizing the coherent large-scale patterns from CMB temperature maps in globally anisotropic cosmologies. The methods we investigate are reasonably general; the particular models we test them on are the homogeneous but anisotropic relativistic cosmologies described by the Bianchi classification. Although the temperature variations produced in these models are not stochastic, they give rise to a "non-Gaussian" distribution of temperature fluctuations over the sky that is a partial diagnostic of the model. We explore two methods for quantifying non-Gaussian and/or non-stationary fluctuation fields in order to see how they respond to the Bianchi models.We first investigate the behavior of phase correlations between the spherical harmonic modes of the maps. Then we examine the behavior of the multipole vectors of the temperature distribution which, though defined in harmonic space, can indicate the presence of a preferred direction in real space, i.e. on the 2-sphere. These methods give extremely clear signals of the presence of anisotropy when applied to the models we discuss, suggesting that they have some promise as diagnostics of the presence of global asymmetry in the Universe.Comment: 14 pages, 10 figures, 4 tables, accepted by MNRA