生产矿山矿体变化特征研究的内容与意义

本文以内蒙古歼汉旗撰山子金矿床为例，对已开采矿脉进行矿体地质研究，定量地表示了矿体变化工，这对指导矿山生产及找矿勘探具有重要的意义。     

An Optimal Control Problem with a Small Parameter

A controlled object with small nonlinearity and two boundary conditions is considered. An integral performance criterion is established. The behavior of optimal value of such an extremal problem is studied as the small parameter tends to zero.     

Analytical modelling of laminated composites

A significant number of research papers has been published on the analytical modelling of composite laminates over the past 20 years. The drive for more accurate analysis has led us to techniques which have become computationally more and more burdensome, while the engineering world continues to use simple, first-older shear deformable plate theory as its primary tool. This paper presents a unique approach to the analysis of thick laminated composites by presenting two simple finite element methods. The first uses the Predictor Corrector technique to extend the simple Mindlin type element to achieve greater accuracy, and the second develops a new Least Squares element which can approximate a C¹ continuous element. The Least Squares element has the capability to incorporate a simplified higher order basis into a piecewise continuous displacement field creating an accurate, yet computationally simple, element. These two methods have the potential to upgrade analysis methods significantly with little additional computational cost. It is hoped that this work can instigate further research into efficient modelling of composite laminates.     

The web of coping resources and pathways to reemployment following a job loss.

Structural equation modeling analyses of data from 2 longitudinal community studies of recently laid-off workers examined the interrelationships and pathways from personal coping resources to job-search intensity and the extent and quality of reemployment at 2 follow-ups (at 6 months and at 12 or 24 months). In both studies, the proposed models for predicting reemployment and reemployment quality provided a good fit to the data with the same pattern of results, which demonstrated that job-search motivation increased reemployment at all follow-ups but did not affect reemployment quality. At both the 6- and 12-month follow-ups, level of depressive symptoms decreased the extent and quality of reemployment. The results also highlighted the dual role of financial strain, which on the one hand facilitates reemployment by increasing job-search motivation and job-search intensity and on the other hand inhibits it by increasing depressive symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chemical reactions and phase transitions

We consider the questions of what effects the fluctuations in fluids near critical points have on the rates and extents of chemical reactions taking place in those fluids and of whether equilibrium polymerizations can be profitably viewed as phase transitions. We find that reaction rates are expected to be affected by critical points only in rare circumstances and that, indeed, there is no compelling experimental evidence for such effects. On the other hand, there is evidence for an effect of critical fluctuations on the extents of chemical reactions at equilibrium, but the effect is not (and is, in general, not expected to be) dramatic. We find that the experimental data on equilibrium polymerizations are in qualitative agreement with predictions based on the n=0 magnet model but that closer consideration and further experimental work are in order.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Phase transition in swollen gels: 7. Effect of charge concentration on the temperature collapse of poly(N,N-diethylacrylamide) networks in water

The swelling and mechanical behaviour of gels of the copolymer of diethylacrylamide (DEAAm) with a small quantity of sodium methacrylate (mole fraction x_MNa = 0–0.067) swollen in water was investigated in the temperature range 1–80°C. For networks in the range x_MNa > 0.0095 phase transition was observed; both the critical transition temperature T_c,c and the extent of the collapse Δ_c increase with increasing x_MNa. The formation of associations in the collapsed state contributes to the overall extent of the transition; these structures give rise to stable turbid gels at elevated temperatures. Evidence for the formation of ‘associated’ structures is also supported by the observed independence of cloud temperature of the concentration of DEAAm, c, in the polymerization DEAAm-water mixture without the crosslinking agent in the range c = 0.5–80 vol%. While PDEAAm solutions are formed in the range c < 4.5–6 vol%, physical gels arise at higher concentrations.     

HX理想染料颜色系统的确立

本文从光的连续性阐述了染料颜色属性,用组合理论推出染料混合组数,分析了目前多数染料品种颜色,确立了有很高实用价值的新的染料颜色系统。它将对印染工作者提高仿样效率提供有力工具。     

A new triangular element to model inter‐laminar shear stress continuous plate theory

An efficient triangular element based on an inter‐laminar shear stress continuous plate theory is developed and applied to the analysis of composite and sandwich plates under different situations to study the performance of the element. The plate theory represents parabolic through thickness variation of transverse shear stresses where the continuity condition of these stresses are satisfied at the layer interfaces. It also satisfies transverse shear stress free condition at the top and bottom surfaces of the plate. The most attractive feature of the plate theory is that the basic unknowns are same as those used in first‐order shear deformation theory. The only problem lies with this elegant plate theory is found in its finite element implementation, as it requires C¹ continuity of transverse displacement at the element interfaces. This is a well‐known problem of thin plate elements, which is also found in some other refined plate theories. Although there are some elements based on these refined plate theories but the number of such elements is very few and they possess certain drawbacks in general. Keeping these aspects in view, an attempt has been made in this study to develop a six‐noded triangular element having equal degrees of freedom at each node. Copyright © 2004 John Wiley & Sons, Ltd.     

On the validity condition of the chi-squared test in 2×2 tables

A 2×2 contingency table is usually analyzed by using the chi-squared asymptotic test, with Yates' continuity correction (c=n/2, wheren is the total size of sample). This correction is the correct one when the chi-squared test is an approximation to Fisher's exact (conditional) test. When the chi-squared test is used as an approximation to Barnard's exact (unconditional) test for comparing two independent proportions (two samples of sizen ₁ andn ₂) or for contrasting independence (one sample with a size ofn), the correctionc is different (c=1 ifn ₁≠n ₂ orc=2 ifn ₁=n ₂ in the first case;c=0.5 in the second). Whatever the case, it is traditional to affirm that the asymptotic test is valid whenE>5, whereE is the minimum expected quantity. Today it is recognized that this condition is too general and may not be appropriate. In the case of Yates' correction. Martín Andrés and Herranz Tejedor (2000) proved that the validity condition must be of the typeE>E ^* —whereE ^* is a known function depending on the marginals of the table—and that checking the validity of the asymptotic test is equivalent to checking the asymmetry of the base statistic (a hypergeometric random variable). In the present article the authors prove that this argument is valid for the other two continuity corrections, and moreover, that the valueE ^* is obtained for all three cases. Given that the functionE ^* reaches an absolute maximum, it can be affirmed that the three chisquared tests referred to are valid whenE<19.2, 14.9 or 6.2 (orE>8.1, 7.7 or 3.9 ifn≤500) respectively for the three previous models (although for the first model and the two-tailed testE>0 is sufficient). This research was supported by the Dirección General de Investigación (Spain). Grant BFM2000-1472.     

流水施工中的关键工作

运用网络计划中关键工作的概念寻求流水施工中的关键工作。为组织流水施工时能抓住主要矛盾,提出了一种直接在垂直图表上判断关键工作的方法。