Properties of estimators of parameters in logistic regression models

Properties of various types of estimators of the regression coefficients in linear logistic regression models are considered. The estimators include those based on maximum likelihood, minimum chi-square and weighted least squares. Theoretical approximations to the biases of the estimators are developed. The results of a large scale simulation investigation evaluating the moment properties of the estimators are presented for the case of a logistic model with a single explanatory variable

The extreme residuals in logistic regression models

Goodness of fit tests for logistic regression models using extreme residuals are considered. Moment properties of the Pearson residuals are developed and used to define modified residuals, for the cases when the model fit is made by maximum likelihood, minimum chi-square and weighted least squares. Approximations to the critical values of the extreme statistics based on the ordinary and modified Pearson residuals are developed and assessed for the case when the logistic regression model has a single explanatory variable

Null distribution of some goodness of fit statistics for logistic regression

The null distribution moment and percentile properties of several goodness of fit statistics for logistic regression models are considered. Small sample approximations to the critical values of the statistics are evaluated for the case of a single explanatory variable with equally spaced values

Design and Experimental Validation of a Ducted Counter-rotating Axial-flow Fans System

An experimental study on the design of counter-rotating axial-flow fans was carried out. The fans were designed using an inverse method. In particular, the system is designed to have a pure axial discharge flow. The counter-rotating fans operate in a ducted-flow configuration and the overall performances are measured in a normalized test bench. The rotation rate of each fan is independently controlled. The relative axial spacing between fans can vary from 17% to 310%. The results show that the efficiency is strongly increased compared to a conventional rotor or to a rotor-stator stage. The effects of varying the rotation rates ratio on the overall performances are studied and show that the system has a very flexible use, with a large patch of high efficient operating points in the parameter space. The increase of axial spacing causes only a small decrease of the efficiencyComment: accepted in Journal of Fluid Engineerin

Guest editorial: Special section on quality control by artificial vision

published_or_final_versio

A combined continuous and interval aerobic training improves metabolic syndrome risk factors in men.

Individuals with metabolic syndrome have significantly higher risk for cardiovascular disease, Type 2 diabetes leading to premature death mortality. Metabolic syndrome has a complex aetiology, thus it may require a combined and multi-targeted aerobic exercise regimen to improve risk factors associated with the metabolic syndrome. Therefore, the aim of this study was to evaluate the effect of combined continuous and interval aerobic training on patients with metabolic syndrome. Thirty adult male with metabolic syndrome (54±8 years) were randomly divided into two groups: Test Training Group (TTG; n=15) or Control Group (CG; n=15). Subjects in TTG group performed combined continuous and interval aerobic training using a motorised treadmill three times per week for 16 weeks. Subjects in CG group were advised to continue with their normal activities of life. Twenty-two men completed the study (11 men in each group). At the end of the study, in TTG group, there were significant (for all, P<0.05) reductions in total body weight (-3.2%), and waist circumference (-3.43 cm), blood pressure (BP; up to -12.7 mmHg), plasma insulin, glucose and triacylglycerides levels. Moreover, there were significant (for all, P<0.05) increases in VO2max (-15.3%) and isometric strength of thigh muscle (28.1%) and HDL in TTG group. None of the above indices were changed in CG group at the end of 16 week study period. Our study suggests that adoption of a 16 week combined continuous and interval aerobic training regimen in men with metabolic syndrome could significantly reduce cardiovascular risk factors in these patients

The influence of incorporation of Mn on the pitting corrosion performance of CrFeCoNi High Entropy Alloy at different temperatures

The electrochemical behavior and susceptibility to pitting corrosion of CrFeCoNi and CrMnFeCoNi high entropy alloys were studied in a 0.1 M NaCl solution at temperatures ranging from 25 to 75 °C. Electrochemical measurements revealed that CrMnFeCoNi is more susceptible to oxide film breakdown and localized corrosion compared to CrFeCoNi. Post corrosion microscopic observations showed severe pitting corrosion for CrMnFeCoNi in higher temperatures compared to CrFeCoNi. Based on in-depth XPS profile measurements on the remaining oxide films, this behavior was attributed to the depletion of Cr in the oxide film and detrimental presence of Mn in the matrix solid solution of CrMnFeCoNi

On-line optical measurement and monitoring of yarn density in woven fabrics

This paper describes a vision-based system that monitors the yarn density of woven fabrics on-line. The system is described in terms of its two principal modules, namely, the image acquisition and the image analysis subsystems. The image acquisition subsystem is implemented with standard components on a low-cost personal computer platform. These components consist of a line-scan camera, a DSP-based image acquisition and processing card, and a host personal computer. The image acquisition process is controlled by a software module that runs on the DSP board and accumulates a 2-D image suitable for the density measurement algorithm. The image analysis sub-system, which also runs on the DSP board, implements a novel, yet straightforward, algorithm that utilizes the discrete Fourier transform for monitoring the yarn density of the fabrics from the acquired images. In this algorithm, the Fourier spectrum of the images is covered by contiguous, concentric annular regions that have a prespecified width. The spectrum values within each annular region are summed, normalized, and subsequently used to produce a 1-D signature. Simple statistics of the obtained signatures are the basis for characterizing the fabric in terms of its yarn density. The described system is tested on seven fabrics with common properties but varying yarn densities and has shown to be accurate within 2 yarns per inch in either direction. It is also shown that the obtained accuracy, which is primarily a function of the image resolution, can be greatly improved

Temperature - dependent life table of the predatory mite, Amblyseius swirskii (Mesostigmata: Phytoseidae) fed on stored product mite Carpoglyphus lactis (Astigmata: Carpoglyphidae)

The predatory mite, Amblyseius swirskii (Athias-Henriot) is an efficient predator of some insect pests particularly thrips and whiteflies. To evaluate the optimum temperature for  A.swirskii, a life table study, based on the age-stage, two-sex life table theory, was conducted using the stored product mite, Carpoglyphus lactis L. as the food diet. Experiments were performed at temperatures of 22, 25, 30 and 32° C, %70 ± 5 relative humidity and 16: 8 (L: D) photoperiod. Developmental time of eggs at 30° C was significantly shorter comparing to the temperatures 22 and 32° C. Developmental time of the mobile pre-adult stages, male and female, were significantly shorter at 32° C, comparing to 25° C. The highest fecundity of the predator was observed at 25° C (72.34 eggs / female). The intrinsic rate of increase (r), finite rate of population increase (λ), net reproductive rate (R0), at temperature of 22° C were 0/226 day-1, 1/25 day-1, 25/53 offspring/individual; at 25° C were 0/304 day-1, 1.35 day-1, 33/82 offspring/ individual; at 30° C were 0/097 day-1, 1/102 day-1, 2/42 offspring/ individual; at a temperature of 32° C were 0/128 day-1, 1/137 day-1, 2/67 offspring/ individual. The population parameters of A. swirskii, except mean generation times (T), at 25° C and 32° C were significantly higher than those at 30° C, and the average generation time (T), at temperature of 22° C, was found to be the highest. The total population projection demonstrated that the highest population growth of predatory mite, A. swirskii occurred at 25° C