Introduction to the special series.

The history of human civilization is marked by efforts to improve the quality of life by delegating laborious tasks to other species or to machines. The newest technological revolution, the use of electronic computers, has produced enormous changes in our lives over the last three decades. Computer technology has been widely applied to many fields of psychology. Psychological assessment, a subspecialty of psychology that served as one of the earliest proving grounds of automated technology, has advanced considerably in the last quarter-century. This Special Series highlights some of the advances in computerized psychological assessment methods and discusses some of the lingering issues and contemporary problems with automated psychological assessment approaches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Steady-state longitudinal vibrations of sectional,physically nonlinear plates

The artile deals with steady-state longitudinal vibrations of plates consisting of curvilinear rings placed one inside the other without interference, under the effect of a harmonic distorting load acting along the outer periphery. The rings are made from different isotropic materials that are physically nonlinear. The problem is solved by the method of successive approximations. In each approximation the sought functions are represented in the form of expansions with respect to a small parameter. Numerical investigations were carried out for plates consiting of two concentrically arranged circular rings.Translated from Problemy Prochnosti, No. 3, pp. 24–27, March, 1991.     

Polymerization Kinetics of Fischer‐Tropsch Reaction on Iron Based Catalysts and Product Grade Optimization

The polymerization kinetics of Fischer‐Tropsch reactions on a K‐promoted Fe catalyst was studied. To represent the product distribution, a kinetic model was developed based on alkyl and alkenyl mechanisms for hydrocarbon chain propagation, which were assumed to occur simultaneously in the Fischer‐Tropsch synthesis. The conclusion was drawn that superimposed Anderson‐Schulz‐Flory (ASF) distributions with different chain growth probabilities, on iron catalysts, can be the result of different chain growth mechanisms. The polymerization mechanism was used to obtain the product distribution for several conditions, and the optimum conditions for the production of transportation fuels were found.     

Synthesis of polypropylene‐graft‐maleic anhydride compatibilizer and evaluation of nylon 6/polypropylene blend properties

Polymer blends based on polyolefins are of a great interest owing to their broad spectrum of properties and practical applications. However, because of poor compatibilities of components, most of these systems generally exhibit high interfacial tension, a low degree of dispersion and poor mechanical properties. It is generally accepted that polypropylene (PP) and nylon 6 (N6) are not compatible and that their blending results in poor materials. The compatibility can be improved by the addition of a compatibilizer, and in this study PP was functionalized by maleic anhydride (MAH) in the presence of an optimized amount of dicumyl peroxide (DCP). The reaction was carried out in the molten state using an internal mixer. Then, once the compatibilizer polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) was prepared, it was added at various concentrations (2.5–10 wt%) to 30/70 glass fibre reinforced N6 (GFRN6) PP, and the mechanical properties were evaluated. It was found that the incorporation of the compatibilizer enhanced the tensile properties (tensile strength and modulus) as well as the Izod impact properties of the notched samples. This was attributed to better interfacial adhesion as evidenced by scanning electron microscopy (SEM). The optimum in these properties was achieved at a critical PP‐g‐MAH concentration. Copyright © 2005 Society of Chemical Industry     

Threshold behavior of the formation of nanometer islands in a Ge/Si(100) system in the presence of Sb

Atomic-force microscopy is used to study the behavior of an array of Ge islands formed by molecular-beam epitaxy on an Si (100) surface in the presence of an antimony flux incident on the surface. It is shown that, as the Sb flux increases to a certain critical level, the surface density of the islands increases; however, if this critical level is exceeded, nucleation of the islands is suppressed and mesoscopic small-height clusters are observed on the surface. This effect is explained qualitatively in the context of a kinetic model of the islands’ formation in heteroepitaxial systems mismatched with respect to their lattice parameters.     

Electroplating of micro-patterned tools via replication of silicone rubber forms

A two-step replication process is described, allowing the non-destructive reproduction of micro-patterned tools. The first step comprises the embedding of the original part into silicone resin, the resin curing, and the separation of the part from the silicone rubber. The outstanding plasticity and the weak adherence of silicone rubber to most substrate materials facilitate retaining the original part. The second replication step, electroforming, requires silicone rubber metallization and contacting. The demonstrated technique is qualified mainly due to successful precautions against replication artifacts, related to silicone rubber deformability.     

Superconductivity at differentTc in CdBa2Ca2Cu3Oy

A Cd analogue of the Tl and Hgn =3 series with nominal composition CdBa₂Ca₂Cu₃O_y has been synthesized. The samples were superconducting according to magnetic susceptibility measurements. The critical temperature was 103 or 107 K depending on the preparation conditions. The EDX analysis revealed the presence of Cd-1111, Cd-1121, and Cd-2333 as minor phases. The observed diamagnetic effects were attributed to the differentT _c of these phases.     

Influence of the prebuckling stress-field on the critical loads of inhomogeneous composite laminates

The paper studies the uniaxial buckling behavior of composite laminates in which preselected variations of fiber spacing in the constituent laminae are adopted. Such laminates are referred to as inhomogeneous laminates because of the variable elastic stiffness along the coordinate axes. A non-uniform prebuckling stress state observed even under constant uniaxial compression has a pronounced influence on the buckling behaviour of an inhomogeneous laminate. A procedure is summarized for computing the critical load of a laminate using the Ritz method which exploits an analogy between the bending and stretching formulations and utilizes Gram-Schmidt orthogonal polynomials. The paper illustrates that the variation in fiber spacing is an innovative way of increasing the critical load for a prescribed amount of fiber and highlights its remarkable sensitivity to the nature of fiber spacing, in-plane and out-of-plane boundary conditions, fiber type and the aspect ratio of the laminate.