Network topology and the theory of rubber elasticity

The earliest investigations on rubber elasticity, commencing in the 19th century, were necessarily limited to phenomenological interpretations. The realisation that polymers consist of very long molecular chains. commencing c. 1930, gave impetus to the molecular theory of rubber elasticity (1932-). according to which the high deformability of an elastomer, and the elastic force generated by deformation, stem from the configurations accessible to long molecular chains. Theories of rubber elasticity put forward from 1934-1946 relied on the assumption that the junctions of the rubber network undergo displacements that are affine in macroscopic strain. The theory of James and Guth (1947) dispensed with this premise, and demonstrated instead that the mean positions of the junctions of a ‘phantom’ network consisting of Gaussian chains devoid of material properties are affine in the strain. The vital significance of the distinction between the actual distribution of chain vectors in a network and their distribution if the junctions would be fixed at their mean positions went unnoticed for nearly 30 years. Experimental investigations, commencing with the incisive work of Gee in 1946. revealed large departures from the relationship of stress to strain predicted by the theories cited. This discrepancy prompted extensive studies, theoretical and experimental, during succeeding years. Inquiry into the fundamentals of polymer networks, formed for example by interlinking very long polymer molecules, exposed the need to take account of network imperfections, typically consisting of chains attached at only one end to a network junction. Various means were advocated to make corrections for these imperfections. The cycle rank ζ of the network has been shown (1976) to be the fundamental measure of its connectivity, regardless of the junction functionality and pattern of imperfections. Often overlooked is the copious interpenetration of the chains comprising typical elastomeric networks. Theories that attempt to represent such networks on a lattice are incompatible with this universal feature. Moreover, the dense interpenetration of chains may limit the ability of junctions in real networks to accommodate the fluctuations envisaged in the theory of phantom networks. It was suggested in 1975 that departures from the form predicted for the elastic equation of state are due to constraints on the fluctuations of junctions whose effect diminishes with deformation and with dilation. Formulation of a self-consistent theory based on this suggestion required recognition of the non-affine connection between the chain vector distribution function and the macroscopic strain in a real network, which may partake of characteristics of a phantom network in some degree. Implementation of the idea was achieved through postulation of domains of constraint affecting the equilibrium distribution of fluctuations of network junctions from their mean positions. This led in due course to a theory that accounts for the relationship of stress to strain virtually throughout the ranges of strain accessible to measurement. The theory establishes connections between structure and elastic properties. This is achieved with utmost frugality in arbitrary parameters.     

Labor-Management Cooperation and Customer Satisfaction

The satisfaction that a customer has with the construction product and construction services provided by a contractor has a direct influence on the customer’s willingness to select that contractor for future work. Labor and management working together have the opportunity to influence customer satisfaction. Activities at the contractor/craft worker level, the contractor/local union level, and the contractor association/local union level have the greatest potential to influence customer satisfaction. A precisely defined plan incorporating labor-management activities targeted at specific satisfaction factors will have the greatest likelihood of creating high customer satisfaction.     

Construction Productivity Improvement

Construction productivity has been on the decline in the last decade. The results are presented on a survey of the Engineering News‐Record 400 largest contractors to obtain their views on where productivity improvements would most help and to compare the trends with a similar survey carried out in 1979. Data were collected on the general company characteristics of the responding contractors, and on the contractors' opinions on potential areas for productivity improvement in the office and in the field. Findings indicate that immediate research should concentrate on improving marketing practices, planning and scheduling, labor‐management relations, site supervision, industrialized building systems, equipment policy and engineering design; and that governmental regulations have lost the immediate urgency attached to them in 1979.It is also recommended that similar surveys be conducted every 3 to 4 years to identify new trends and to steer research in the appropriate direction.     

光学全交叉网络与SW榕树（F＝S＝2）网络拓扑等价的多样性

本文对有关互连网络拓扑等价的分析方法作了简单评述。并采用互连网络拓扑等价的图分析法分析了自由空间光学互连全交叉网络与ＳＷ榕树网络的拓扑等价及其多样性，拓展了全交叉网络在数字光计算、光子交换及多处理机系统的潜在应用。     

Mixture of probability distributions as a basic component in simulating measurement accuracy

A stochastic model is proposed for a basic mechanism in the formation of uncertainties in physical quantity measurements. __________ Translated from Izmeritel'naya Tekhnika, No. 1, pp. 12–17, January, 2006.     

Perverse Spite: The Possessive Gleam in the Mother's Eye and the Struggle to Own One's Soul: Reply to Stern (2004).

In this response to Jeffrey Stern's (2004) (see record 2004-21113-016) commentary on my article, "Giving the Devil His Due: Spite and the Struggle for Individual Dignity" (P. Shabad, 2000) (see record 2000-00917-004), I suggest that in emphasizing the conscious vindictiveness of explicit spite, Stern minimizes the perverse aspects of "cutting off one's nose to spite one's face" as a means of avenging oneself against powerful others. The underlying impetus of perverse spite is to break free from the prison of subtle developmental contingencies and unconscious seductions surrounding maternal possessiveness. When the child's self-assertive strivings are blocked because of the shame and fear of premature separateness, the inward obsessional churning of resentment becomes a fertile ground for perverse spite. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonlinear Stress-Strain Relationship of Soil Reinforced with Flexible Geofibers

A nonlinear stress-strain relationship of soil reinforced with flexible geofibers under static loading is derived based on a nonlinear elastic stress-strain relationship of soil and a linear elastic stress-strain relationship of geofibers in the paper. This investigation includes the following aspects: First, the homogenization technique is introduced to find the volume average stress tensor and volume average strain tensor and further an elastic incremental stress-strain relation is introduced to describe deviatoric shear stress-axial strain relationship of equivalent homogeneous geofiber-reinforced soil. Second, the relation of geofiber numbers, content, mechanical behavior, distribution, and geometrical features to shear modulus of geofiber-reinforced soil is expressed and assessed by employing an elastic energy method. Third, the deviatoric shear stress and axial strain curves of geofiber-reinforced soil are calibrated by laboratory testing data of geofiber reinforced soil samples. Finally, the theoretical computational curves of geofiber reinforced soil are compared with the curves calibrated by testing data of geofiber reinforced soil. The model prediction has a good agreement with experimental results.     

企业内部公关与企业形象塑造

良好的企业形象是竞争取胜的利器，内部公关是塑造良好企业形象的根本手段。本文阐述了企业内部公关对塑造良好企业形象的重要意义，探讨了实施内部公关的主要途径。     

Epoxidation of high trans‐1,4‐polyisoprene and its properties

A new organic‐solvent‐free water‐phase suspension method was used to synthesize partially epoxidized high trans‐1,4‐polyisoprene (TPI) to improve its properties, including oil resistance and wet‐skid resistance. The epoxidation was conducted in an aqueous peracetic acid solution and on the TPI granules prepared by a bulk precipitation method with supported titanium catalyst. The effects of the synthesis conditions, including reaction temperature, reaction time, and pH value, on the epoxy content were investigated. Epoxidized trans‐1,4‐polyisoprene (ETPI) with epoxy contents between 10 and 80% were obtained within 4 h. Both the amorphous and crystalline regions of TPI were epoxidized. The crystallization properties decreased with increasing epoxy content. ETPIs possessed lower mechanical properties than TPI but could be enhanced by vulcanization. The oil resistance and wet‐skid resistance were significantly improved after epoxidation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Child negative emotionality and parenting from infancy to preschool: A meta-analytic review.

This meta-analytic review (k = 62 studies; N = 7,613 mother-child dyads) shows that effect sizes for the association between child negative emotionality and parenting were generally small and were moderated by sample and measurement characteristics. The association between more child negative emotionality and less supportive parenting was relatively strong in lower socioeconomic status families, reversed in higher socioeconomic status families, and limited to studies with relatively high percentages of participants from ethnic minorities and studies using parent report to assess negative emotionality. Higher levels of child negative emotionality were associated with more restrictive control in samples with less than 75% 1st-born children, as well as in infants and preschoolers, and in studies using parent report or composite measures to assess both negative emotionality and restrictive parenting. Finally, more child negative emotionality was associated with less inductive control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)