Chapter 8 Estimating production frontier shifts: An application of DEA to technology assessment

Evaluating the separate impacts of factors which affect the productive efficiency of organizations is difficult. This is because the impact of a factor is often contingent on other organizational, managerial or environmental characteristics. Standard econometric methods are limited in their ability to discriminate between efficient and inefficient units, and often impose considerable structure in parametrically specified functional forms. We show how a nonparametric data envelopment approach can be employed to focus on the best that can be achieved, with and without the key characteristic of interest. We illustrate the approach with real data from the service sector requiring the evaluation of the impact of a new information technology. The analytical technique estimates the annual savings in materials cost for an average store using the information technology to be over $4,000 (2.04% of materials cost), well in excess of the amortized annual cost for its installation. Establishing the separation in the production frontier in different regions, we show that the information technology had a substantially larger impact for the bigger stores. The savings were about 80% greater in the larger volume stores than in the smaller volume operations, an important consideration in setting the priorities for installation. The illustration underscores the flexibility of DEA in detecting different impacts of a new technology in different environments.     

Properties and applications of forests of quadtrees for pictorial data representation

Region representation as a quadtree data structure is a rich field in computer science with many different approaches. Forests of quadtrees offer space savings over regular quadtrees by concentrating the vital information [4, 5, 6]. They scavenge unused and unneeded space (i.e., node containing no information). This paper investigates several properties of forests of quadtrees which can be used to design manipulation algorithms for forest-quadtree data structure. In addition, the paper discusses the space saving and shows how the basic operations that can be performed on a quadtree can also be done on the more space efficient representation (a forest of quadtrees).     

Viscosities of binary solutions of non-electrolytes

Viscosities and molar volumes of binary solutions,viz., Toluene-Nitrobenzene, Toluene-Bromobenzene, Toluene-Cyclohexanone, Cyclohexane-Cyclohexanone, Cyclohexane-Nitrobenzene, Cyclohexane-Acetic acid, Cyclohexane-Propionic acid and Cyclohexane-Butyric acid have been measured. The experimental results have been discussed in terms of viscosity-composition relations developed for binary solutions by Grunberg and Nissan and Katti and Chaudhri.     

The new physiology of vision

Exchange of intensities among various spectra of Mn²⁺ in NaCl single crystal, corresponding to Mn⁺² ion associated with various point defects, is described as a function of temperature and time. The variation of line width with temperature is discussed. The fine structure parameter D for a particular spectrum is measured with temperature and is shown to behave like D=D₀ (1+bT+cT²). Thermal formation of new complexes and their lifetimes are discussed. A new short-lived complex is found and a model for the same is suggested.     

A point implicit unstructured grid solver for the euler and Navier–Stokes equations

An upwind finite element technique that uses cell-centred quantities and implicit and/or explicit time marching has been developed for computing hypersonic laminar viscous flows using adaptive triangular grids. The approach is an extension to unstructured grids of the LAURA algorithm due to Gnoffo. A structured grid of quadrilaterals is laid out near a solid surface. For inviscid flows the method is stable at Courant numbers of over 100000. A first-order basic scheme and a higher-order flux-corrected transport (FCT) scheme have been implemented. This technique has been applied to the problem of predicting type III and IV shock wave interactions on a cylinder, with a view to simulating the pressure and heating rate augmentation caused by an impinging shock on the leading edge of a cowl lip of an engine inlet. The predictions of wall pressure and heating rates compare very well with experimental data. The flow features are distinctly captured with a sequence of adaptively generated grids.     

On the thermodynamics of an ideal fermi gas on the lattice at finite density

We study the ideal gas of fermions on a lattice at finite density for both naive and Wilson fermions. Comparing the thermodynamical quantities thus calculated with the known results in the continuum theory, we are led to propose a modification of the naive form of the lattice action, which is same for both the naive and the Wilson fermions. The thermodynamical quantities, calculated by using this form, are shown to have the correct continuum limit.     

BISTAB: A portable bifurcation and stability analysis package

A portable bifurcation and stability analysis package, called BISTAB, is described. The package is written in FORTRAN V and can follow the connected set of equilibrium curves for a system of nonlinear ordinary differential equations in the state × parameter space by varying a bifurcation parameter. The curves are traced from an initial point with the continuation method of Kubicek, and the tangent method of Keller is used to find initial points on bifurcating curves near simple bifurcation points. Linearized stability analysis, location of Hopf bifurcation points, and sorting of points for plotting are also supported. While the package contains no new numerical methods, the lack of a requirement for any derivative information higher than the Jacobian makes BISTAB computationally efficient and useful for applied problems where nonnumerical bifurcation analysis may be difficult.