Orientational effect of mica in fumed silica reinforced composites

Infrared and birefringence measurements are used to characterize the orientational behavior of fumed silica and mica hybrid‐reinforced poly(dimethylsiloxane) composites. Results of equilibrium stress–strain and swelling experiments are also reported and correlated with the orientational data. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 215–222, 2001     

Work-input model for assembly and disassembly of high shoring towers

High shoring towers, the common shoring solution for high clearance construction, cause the entire formwork system to account for a remarkably high percentage of the cost of the constructed concrete element. However, data on work inputs in assembly and disassembly of high towers are scarce, and the reason lies in the difficulty in conducting the numerous work studies that would be needed to cover the wide variety of tower types offered by the market and the extensive range of heights to which towers are erected. A model is presented, based on a limited number of work studies, for the prediction of work inputs in the assembly and disassembly of shoring towers of two configurations, rising to heights of up to 30 m. Results of actual measured work input data for three tower models representing three tower types widely used on construction sites are presented. An insight is provided into the anatomy of tower erection, which should make possible use of the proposed methodology for the development of similar models for additional tower types.     

Towards a contingent approach of customer involvement in defence projects: An exploratory study

This paper reports the main results of an exploratory, multiple case study investigating customer involvement practices in system development projects in the Israeli defence industry. The study proposes and examines a theoretical contingency model regarding the effect of customer involvement modes on project success, moderated by project characteristics. It focuses specifically on the working mode of customers' representatives along the continuum between external supervision to full participation in project activities.     

Control of mineral wool thickness using predictive functional control

The production process of mineral wool is affected by several constantly changing factors. The ingredients for the mineral wool are melted in a furnace. The molten mineral charge exits the bottom of the furnace in a water-cooled trough and falls into a fiberization device (the centrifuge). The centrifuge forms the fibers. At this stage binders are injected to bind the fibers together. To ensure the quality of the end product (the consistent thickness) the flow of the bounded fibers must be as constant as possible. One way to ensure that is to control the speed of the conveyor belt that transports the bounded fibers from the centrifuge to the curing process. Predictive functional controller and PID controller are considered to replace an existing algorithm. Both can easily replace an existing one as they do not require any new sensor installation. All three algorithms are presented and tested on a developed plant model. The study showed that the predictive control gives better results than the existing and PID controller.     

Sabbatical leave: Who gains and how much?

A rigorous quasi-experiment tested the ameliorative effects of a sabbatical leave, a special case of respite from routine work. We hypothesized that (a) respite increases resource level and well-being and (b) individual differences and respite features moderate respite effects. A sample of 129 faculty members on sabbatical and 129 matched controls completed measures of resource gain, resource loss, and well-being before, during, and after the sabbatical. Among the sabbatees, resource loss declined and resource gain and well-being rose during the sabbatical. The comparison group showed no change. Moderation analysis revealed that those who reported higher respite self-efficacy and greater control, were more detached, had a more positive sabbatical experience, and spent their sabbatical outside their home country enjoyed more enhanced well-being than others. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The jury and abjury of my peers: The self in face and dignity cultures.

The self is defined and judged differently by people from face and dignity cultures (in this case, Hong Kong and the United States, respectively). Across 3 experiments, people from a face culture absorbed the judgments of other people into their private self-definitions. Particularly important for people from a face culture are public representations—knowledge that is shared and known to be shared about someone. In contrast, people from a dignity culture try to preserve the sovereign self by not letting others define them. In the 3 experiments, dignity culture participants showed a studied indifference to the judgments of their peers, ignoring peers' assessments—whether those assessments were public or private, were positive or negative, or were made by qualified peers or unqualified peers. Ways that the self is “knotted” up with social judgments and cultural imperatives are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On quarter-point three-dimensional finite elements in linear elastic fracture mechanics

Use of the finite element method for calculating stress intensity factors of two-dimensional cracked bodies has become commonplace. In this study, the more difficult task of applying finite elements to three-dimensional cracked bodies is investigated. Since linear elastic material is considered, square root singular stresses exist along the edge of an embedded crack. To deal with this numerical difficulty, twenty noded, isoparametric, serendipity, quarter-point, singular, solid elements are employed. Examination of these elements is carried out in order to determine the extent of the singular behavior.In addition, the stiffness derivative technique is explored, together with quarter-point elements, to determine an accurate procedure for computing stress intensity factors in three-dimensions. The problem of chosing a proper virtual crack extension is addressed. To this end, the disturbance in the square root singular stresses is examined and compared with a similar disturbance which occurs in two-dimensions. As a numerical example, a pennyshaped crack in a finite height cylinder is considered with various meshes. It is found that stress intensity factors can be calculated to an accuracy within 1 percent when quarter-point cylindrical elements are employed with the stiffness derivative technique such that the crack extension is one in which one corner node is not moved, the other corner node is moved a small distance, and the midside node is moved one-half that distance. This crack extension is analogous to that of a straight crack advance for a brick element. Both of these crack advances disturb the square root singular stresses in a manner similar to that which occurs with the two-dimensional eight noded element in which the crack has been advanced a small distance.     

Analyzing Dynamic Behavior of Geosynthetic-Reinforced Soil Retaining Walls

An advanced generalized plasticity soil model and bounding surface geosynthetic model, in conjunction with a dynamic finite element procedure, are used to analyze the behavior of geosynthetic-reinforced soil retaining walls. The construction behavior of a full-scale wall is first analyzed followed by a series of five shaking table tests conducted in a centrifuge. The parameters for the sandy backfill soils are calibrated through the results of monotonic and cyclic triaxial tests. The wall facing deformations, strains in the geogrid reinforcement layers, lateral earth pressures acting at the facing blocks, and vertical stresses at the foundation are presented. In the centrifugal shaking table tests, the response of the walls subject to 20 cycles of sinusoidal wave having a frequency of 2 Hz and of acceleration amplitude of 0.2g are compared with the results of analysis. The acceleration in the backfill, strain in the geogrid layers, and facing deformation are computed and compared to the test results. The results of analysis for both static and dynamic tests compared reasonably well with the experimental results.     

Adding a temporal dimension to a logic system

We introduce a methodology whereby an arbitrary logic system L can be enriched with temporal features to create a new system T(L). The new system is constructed by combining L with a pure propositional temporal logic T (such as linear temporal logic with Since and Until) in a special way. We refer to this method as adding a temporal dimension to L or just temporalising L. We show that the logic system T(L) preserves several properties of the original temporal logic like soundness, completeness, decidability, conservativeness and separation over linear flows of time. We then focus on the temporalisation of first-order logic, and a comparison is make with other first-order approaches to the handling of time.