Fundamental frequency analysis of laminated rectangular plates by differential quadrature method

In this paper a differential quadrature method is presented for computation of the fundamental frequency of a thin laminated rectangular plate. The partial differential equations of motion for free vibration are solved for the boundary conditions by approximating them by substituting weighted polynomials functions for the differential operator. By doing this, the coupled partial differential equations of motion are reduced to sets of homogeneous algebraic equations. These sets of homogeneous algebraic equations are combined to give a set of general eigenvalue equations for the problem. Three types of laminated plate problems, which include symmetric, antisymmetric cross-ply, and symmetric, balanced angle-ply laminates, are analysed by the method and the results obtained are compared with solutions reported in the literature for other numerical methods. The effects of the level of discretization on the accuracy and rate of convergence of the results are also discussed. The method presented gives accurate results and is found to use not much computer time.     

Investigations of absenteeism: Using event history models to study the absence-taking process.

Traditional correlational and regression analyses of aggregated absences are ill-suited for estimating parameters of the absence-taking process. A class of event history models is described that effectively deals with the distributional and temporal properties of absences. One such model, a proportional hazard rate model, was applied to the daily attendance records of 2,130 incumbent, white-collar employees of a national financial service organization. Temporal and historical variables affected the hazard rate of voluntary absence taking. Demographic variables that were significantly correlated with aggregated absences did not improve prediction of the hazard rate. Consequences of violating the modeling assumptions of independent observations and large samples were examined empirically. Results indicated that the model was robust to such violations. Implications of the findings and of the successful application of the model are discussed. Several recommendations are made for using the model in organizations and for future studies of absence taking and other low base-rate events in organizations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Leadership orientation as a function of interpersonal need structure.

Examined the relationship of interpersonal need structure as measured by the Fundamental Interpersonal Relations Orientation-Behavior Questionnaire (FIRO-B) to leadership orientation as measured by the Leadership Opinion Questionnaire (LOQ) and the Least Preferred Co-Worker Scale (LPC); Ss were 245 1st- and 2nd-level supervisors. The LPC score and the Consideration dimension of the LOQ were found to be positively related to all the FIRO-B scales except Expressed Control. Initiating Structure was positively related to Expressed Control. The LPC score was negatively related to Initiating Structure and positively related to Consideration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variations à l’échelle submicroseconde des champs électromagnétiques rayonnes par la foudre

Electric fields (E) and electric field derivative signals (dE/dt) radiated by lightning have been recorded using a system with 40 ns and 10 ns response times respectively. Propagation between the source and the measuring station was entirely over the ocean (high electrical conductivity) so signal distortion below 20 MHz was minimal. Large normalized (to 100 km) electric field derivative values, from 10 to 40 V/m/μs, have been observed during return strokes, leader and intracloud discharge processes. Corresponding mean values of the maximum current derivative, estimated using the transmission line model, range from 80 to 154 IcA/μs, depending on the type of discharge and assuming a wavefront velocity of 10 ⁸ m/s.     

Molecular weight and polydispersity measurements of polystyrene by quasielastic light scattering

The molecular weight and polydispersity of a polydisperse polystyrene sample was measured by quasielastic light scattering. The molecular weight distribution of the polymer was represented by the Schultz distribution. The weight average molecular weight and polydispersity of distribution was adjusted until the quasielastic light scattering spectra calculated for the distribution agreed with the measured spectra. The calculation was repeated using the logarithmic normal distribution for the polymer. The calculated value of the weight average molecular weight is accurate and insensitive to the assumed molecular distribution function. However, the calculated values of the polydispersity are only of fair accuracy. Thus quasielastic light scattering gives values of the weight average molecular weight at least as accurate as elastic light scattering and gives a crude estimate of the polydispersity of the polymer.     

Investment planning for the development of a national resource —linear programming based approaches

This paper will review and generalize the work of Gearing, Swart and Var dealing with the development of a mathematical model to aid the government of Turkey in determining the “best” allocation of the capital budget for tourism among a large group of competing proposals. One of the more unique aspects of this work was the development of a measure of benefit for particular allocation plans which allowed for subjective information to be an integral part of the investment planning model.The computational procedures developed heretofore to derive investment strategies from the model have been based on dynamic programming, integer programming or combined dynamic programming-integer programming approaches. This paper will show how various methods based on linear programming yield satisfactory answers to many questions regarding development policies. The primary advantage of these linear programming methods is that they can be implemented with standard linear programming computer packages which are generally available, and hence eliminate the high cost of developing special purpose computer codes.     

Effects of castration and replacement therapy on sexual behavior of adult male rhesuses.

Observed the sexual behavior of 10 male rhesus monkeys before and after castration and during replacement therapy with testosterone propionate. In 10 tests before castration, all of the Ss ejaculated at least once, and in Weeks 21-25 and 51-55 after castration, 50 and 30%, respectively, ejaculated at least once. In the 35 postcastration tests given over a 55-wk period, 2 males did not ejaculate. 50% of the Ss achieved intromission 1 yr after castration. The percentage of castrated Ss showing intromission and ejaculation and the frequency of these responses were higher than those reported for most nonprimate species but did not differ greatly from those reported for the dog. Within 1 wk testosterone propionate restored whatever aspects of behavior were affected to precastration levels. (22 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)