Resource allocation for performance improvement

In this paper the problem of allocating resources among Decision Making Units is considered. This study covers the case in which several homogeneous units are operating under the supervision of a central unit. The resource allocation is carried out by the DM (central unit) in such a way that the overall performance of the system is improved. Performance is defined by means of a convex combination of the ratio of the efficiencies before and after the resource allocation. It is assumed that each unit is allowed to modify its resources within the current production possibility set. A novel model is proposed which aims at achieving the best performance of the system. The method is capable of dealing with some additional constraints, imposed by the DM. The model is illustrated by a simple numerical example and a real application.     

Efficiency analysis to incorporate interval-scale data

We develop an approach to efficiency analysis to enable us to incorporate interval-scale data in addition to ratio-scale data. Our approach introduces a measure of inefficiency and identifies efficient units as is done in Data Envelopment Analysis. The basic idea in our approach is to find the “best” hyperplane separating the units that are better and worse than each unit. “Best” is defined in such a way that the number of not-better units is maximal. The efficiency measure is defined as a proportion of not-better units to all units. The results are invariant under a strictly increasing linear re-scaling of any input- or output-variables. Thus zeroes or negative values do not cause problems for the analysis. The approach is used to analyze the data of the research evaluation exercise recently carried out at the University of Joensuu, Finland.     

Choice behavior in interactive multiple-criteria decision making

Choice behavior in an interactive multiple-criteria decision making environment is examined experimentally. A free search discrete visual interactive reference direction approach was used on a microcomputer by management students to solve two realistic and relevant multiple-criteria decision problems. The results revealed persistent patterns of intransitive choice behavior, and an unexpectedly rapid degree of convergence of the reference direction approach on a preferred solution. The results can be explained using Tversky' [20] additive utility difference model and Kahneman-Tversky's [5] prospect theory. The implications of the results for the design of interactive multiple-criteria decision procedures are discussed.     

Association between visual degeneration of intervertebral discs and the apparent diffusion coefficient

The value of apparent diffusion coefficient (ADC) measurements in intervertebral disc has been studied because ADC provides an estimate of free diffusion of unbound water and could be used as a quantitative tool to estimate degenerative changes. However, the challenging nature of diffusion imaging of spine and limited numbers of subjects in earlier studies has produced contradictory findings. We aimed to determine the relation between ADC and visual degenerative changes in lumbar intervertebral discs in a sufficiently large homogeneous study group. Lumbar spines of 228 volunteer middle-aged men were MR imaged at 1.5 T including anatomic and diffusion-weighted imaging. ADC values, T2 signal intensity and height, and width of the three lowest lumbar intervertebral discs were measured and disc degeneration visually graded. The calculated average ADC of 530 measured discs was 2.01×10⁻³ mm²/s±0.29 (±S.D.). The reduction in ADC between visually normal and moderately degenerated discs was 4%. Severely degenerated discs showed 5% larger ADC values than normal discs, presumably due to free water in cracks and fissures of those discs. T2 signal intensity of the disc was significantly correlated with the ADC values, whereas other measured parameters did not show correlation. There was no evident difference in ADC between the studied anatomic lumbar levels. Because there is considerable overlap between ADC values of normal and degenerated discs, we conclude that ADC measurements of intervertebral discs, at least with current technology, have limited clinical value.     

Methods of artificial enlargement of the training set for statistical shape models

Due to the small size of training sets, statistical shape models often over-constrain the deformation in medical image segmentation. Hence, artificial enlargement of the training set has been proposed as a solution for the problem to increase the flexibility of the models. In this paper, different methods were evaluated to artificially enlarge a training set. Furthermore, the objectives were to study the effects of the size of the training set, to estimate the optimal number of deformation modes, to study the effects of different error sources, and to compare different deformation methods. The study was performed for a cardiac shape model consisting of ventricles, atria, and epicardium, and built from magnetic resonance (MR) volume images of 25 subjects. Both shape modeling and image segmentation accuracies were studied. The objectives were reached by utilizing different training sets and datasets, and two deformation methods. The evaluation proved that artificial enlargement of the training set improves both the modeling and segmentation accuracy. All but one enlargement techniques gave statistically significantly $(p ≪ 0.05)$ better segmentation results than the standard method without enlargement. The two best enlargement techniques were the nonrigid movement technique and the technique that combines principal component analysis (PCA) and finite element model (FEM). The optimal number of deformation modes was found to be near 100 modes in our application. The active shape model segmentation gave better segmentation accuracy than the one based on the simulated annealing optimization of the model weights.      

Effect of charge transfer efficiency on image quality in CCD line scan-based web inspection

Charge transfer efficiency limits the performance of a CCD line scan-based imaging system. Even though the degradation of the image quality due to the inefficiency in the charge transfer is often neglected in practical work it may have considerable effect on the system performance in applications where high resolution and uniform image quality are needed. In this paper the relationship between the charge transfer efficiency and the image quality in paper web inspection and, especially, in streak detection is discussed. A simple method for the estimation of the charge transfer efficiency is proposed. The method is based on the imaging of a square wave test pattern. The degradation of the image quality due to the charge transfer is analysed both theoretically and with practical imaging experiments. The results show clearly the variation in the system performance along the CCD scan. This is emphasised in the case of small and low-contrast surface defects on the web.     

Notes on the complexity of sorting in abstract machines

The complexity of sorting with pointer machines and successor-predecessor random access machines is studied. The size of the problem is defined as the length of the problem string. A linear time algorithm is achieved for sorting by pointer machines. For successor-predecessor random access machines linear time is sufficient in a special case.     

High-resolution Fourier transform study of the perpendicular band ν11 of allene at 353 cm−1

The ν₁₁ perpendicular band of the allene (propadiene) molecule was measured in the region 310–390 cm^?1 on a high-resolution Fourier transform instrument. A total of 1880 lines was assigned to 22 subbands with KΔK values between ?10 and +12. Subband constants which reproduce the observed line positions with standard deviations of 0.0005-0.0008 cm^?1 are tabulated. The strong effects of the two types of l-type interactions allowed for this molecule are included in the Hamiltonian matrix used for the treatment of the spectrum and for the least-squares adjustment of the spectroscopic constants for the ν₁₁ state. A table of the rovibrational energy levels of the ν₁₁ state is given to facilitate analysis of the various hot bands observed throughout the spectrum of allene. Improved estimates are obtained for the elusive rotational constant, A₀, and for the centrifugal constant, D_K⁰, by combining published Raman data for the ν₁₁ band with the new accurate infrared measurements.