Numerical trials of HISSE

The mathematical description and implementation of the statistical estimation procedure known as the Houston integrated spatial/spectral estimator (HISSE) is discussed. HISSE is based on a normal mixture model and is designed to take advantage of spectral and spatial information of LANDSAT data pixels, utilizing the initial classification and clustering information provided by the AMOEBA algorithm. The HISSE calculates parametric estimates of class proportions which reduce the error inherent in estimates derived from typical classify and count procedures common to nonparametric clustering algorithms. It also singles out spatial groupings of pixels which are most suitable for labeling classes. These calculations are designed to aid the analyst/interpreter in labeling patches with a crop class label. Finally, HISSE's initial performance on an actual LANDSAT agricultural ground truth data set is reported

Capital Structure and Investment Behaviour of Malaysian Firms in the 1990s: A Study of Corporate Governance before the Crisis

This is an empirical study analyzing the corporate finance and governance structure in Malaysia before and after the financial crisis of 1997, utilizing the agency cost approach. The contribution of this paper is to link the corporate governance mechanism with the role of banks and corporate ownership structure taking into account the institutional framework and historical background of the Malaysian financial system. Based on data for 375 non-financial KLSE (Kuala Lumpur Stock Exchange) listed companies during fiscal years 1995-99, our analysis is organized into three parts. Section 2 outlines characteristics of corporate finance in Malaysia in the 1990s using aggregated time-series data. Section 3 examines determinants of capital structure via cross-sectional regressions in terms of dependency on banks, availability of internal funds, ownership concentration, ethnic ownership structure, industry effects, etc. And in section 4, we estimate simple investment functions with panel data in order to examine the effects of debt financing on corporate investments before the crisis. Empirical results show that the commitment of banks to finance corporate debt as well as lending obviously increased debt ratios. Ownership concentration mitigates conflict between managers and owners. Foreign ownership also contributed to a reduction in the agency costs of equity financing. However, increasing ownership by native Malays (Bumiputera), both the direct and indirect holding of corporate shares, played no significant role in disciplining corporate management. Finally, high dependency on debt led to excessive corporate investment before the crisis. These results imply that the concentration of risks on the banking sector and social policy advocating the dispersion of corporate ownership weakened the corporate governance mechanism, thereby exacerbating the distress of Malaysia's corporate sector during the financial crisis.

An iterative procedure for obtaining maximum-likelihood estimates of the parameters for a mixture of normal distributions

A general iterative procedure is given for determining the consistent maximum likelihood estimates of normal distributions. In addition, a local maximum of the log-likelihood function, Newtons's method, a method of scoring, and modifications of these procedures are discussed

The numerical evaluation of the maximum-likelihood estimate of a subset of mixture proportions

Necessary and sufficient conditions are given for a maximum likelihood estimate of a subset of mixture proportions. From these conditions, likelihood equations are derived satisfied by the maximum-likelihood estimate and a successive-approximations procedure is discussed as suggested by equations for numerically evaluating the maximum-likelihood estimate. It is shown that, with probability one for large samples, this procedure converges locally to the maximum-likelihood estimate whenever a certain step-size lies between zero and two. Furthermore, optimal rates of local convergence are obtained for a step-size which is bounded below by a number between one and two

Horn antenna with v-shaped corrugated surface

Corrugated shape is easily machined for millimeter wave application and is better suited for folding antenna designs. Measured performance showed ""V'' corrugations and rectangular corrugations have nearly the same pattern beamwidth, gain, and impedance. Also, ""V'' corrugations have higher relative power loss