Cad for analysis and synthesis of MM-wave transmission lines

This work presents a software for analysis and synthesis of four types of planar lines used on the millimeter wave band: Suspended Microstrip Line, Inverted Microstrip Line, Suspended Stripline and Broadside Coupled Stripline. Conceived for IBM/PG or compatible microcomputers, the program, (MMWL), can study each configuration at a time or all of them at once, and it does not matter if it is synthesis or analysis for each line at the same time. The results are presented in Tables shown in the same screen. The program also provides curves of characteristic impedances against conducting strip width for each one of studied structures. Therefore, it allows choosing the best combination for circuit realization, becoming a helpful tool for projects and with acceptable results.

     

The corrosion behaviour of Cr/Co/Mo-alloyed low residual carbon steels in seawater solutions

The general corrosion behaviour of low residual steels alloyed with chromium or cobalt or molybdenum in seawater solutions was studied. The carbon content of low residual steels ranged from 0.1 to 0.4%, chromium content between 1.0 and 4.0%, cobalt content between 1.0 and 3.0%, and molybdenum content between 0.3 and 1.0%. Repeated laboratory tests demonstrated that low levels of chromium reduce the dissolution rate of low residual steels in seawater solutions. The results of this study suggest that cobalt alloying plays a neutral role, whereas molybdenum plays a major role in reducing the corrosion rates, particularly in higher carbon steels.     

Mental health providers' perceptions of cultural variables in evaluating ethnically diverse clients.

The study assessed anonymously the perceptions of 107 mental health providers concerning the importance of considering cultural variables in the assessment of mental disorders in ethnic minority individuals. Although the providers overwhelmingly reported a belief in the importance of cultural variables, a relatively small percentage considered themselves highly successful in assessing the degree of the clients' assimilation and acculturation. Additionally, 73% of the respondents reported a high degree of need for more culturally focused training. The results indicate the need to increase such training in order to better serve minority individuals and the possible need to increase the numbers of mental health providers serving minority clients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimal linear approximation in project compression

When the cost of reducing the duration of activities is convex and nonlinear, it may be advisable (to reduce the computing burden) to seek a “satisficing” answer, in which the project is compressed to a desired completion time with a prespecified tolerable relative error. We treat the problem of constructing the optimal first degree interpolating linear spline that guarantees such maximal error and consider various possible refinements.     

Strays-insensitive switched-capacitor filters based on bilinear Z-transform

Biquadratic circuits are introduced which enable the exact design of switched-capacitor filters using the bilinear z-transform. The resulting filters are completely insensitive to stray capacitances, and meet their specifications up to and including one-half the sampling frequency.     

Computer simulation for a solar heating system

In this paper a simulation model for a basic solar heating system which is suitable for control and optimization studies is developed. A model for flat plate solar collectors using fluids for the heat transfer which allows the analysis of operation in great detail is presented. The simulation model for the solar collectors has also the characteristic that its inputs and outputs are quantities which are easily measurable in the real world. The effect of temperature stratification in the heat storage device model is considered by simulating two storage chambers of variable volume. The heat storage model requires relatively small time increments, a requirement which is not as stringent as that for the solar collectors. The tank's model primary variables are the easily measurable quantities of temperature and flow rates with the addition of volume as an internal variable. Weather, load and control modeling is also presented. The gradient search method is then applied to study optimal sizing of solar heating components of The University of Toledo solar house.     

The coefficient of performance for a solar absorption dual cycle

The traditional definition of the coefficient of performance (COP) can create misleading results because this definition does not define the heat input base to be used for estimating the COP. Furthermore, such one-dimensional definitions do not consider other important factors which may affect the system selection.

A new selection criterion for a solar powered dual absorption system will be presented in this paper. The dual cycle, which has the advantage of not using a cooling tower, has often been ignored because of the misleading definition of the COP.

The present paper also describes a lithium bromide dual absorption cycle.