Combined stress experiments on a nickel-chrome-molybdenum steel

Combined static stress experiments are discribed in which thin walled tubes of a nickel-chrome-molybdenum steel are subjected to combined axial tension and internal pressure, and to combined axial compression and internal pressure. The axial loading was applied by means of a 30 ton hydraulic testing machine and the internal pressure by a pendulum dynamometer and pump. Tangential strains were measured by two newly developed hydraulic lateral extensometers, one of which was used in the axial tension experiments and the other in the axial compression tests. These extensometers possess the advantage over previous types for this work in that they measure accurately the average of the tangential strains over a considerable length of the tubes instead of at a single cross-section. Axial strains were measured with a Martens extensometer. Additional torsion tests are described. The experimental results checked well with the recently suggested constant energy of distortion theory of strength.     

Comparison of digoxin concentration in plastic serum tubes with clot activator and heparinized plasma tubes

Introduction:

Sample type recommended by the manufacturer for the digoxin Abbott assay is either serum collected in glass tubes or plasma (sodium heparin, lithium heparin, citrate, EDTA or oxalate as anticoagulant) collected in plastic tubes. In our hospital samples are collected in plastic tubes. Our hypothesis was that the serum sample collected in plastic serum tube can be used interchangeably with plasma sample for measurement of digoxin concentration. Our aim was verification of plastic serum tubes for determination of digoxin concentration.

Materials and methods:

Concentration of digoxin was determined simultaneously in 26 venous blood plasma (plastic Vacuette, LH Lithium heparin) and serum (plastic Vacuette, Z Serum Clot activator; both Greiner Bio-One GmbH, Kremsmünster, Austria) samples, on Abbott AxSYM analyzer using the original Abbott Digoxin III assay (Abbott, Wiesbaden, Germany). Tube comparability was assessed using the Passing Bablok regression and Bland-Altman plot.

Results:

Serum and plasma digoxin concentrations are comparable. Passing Bablok intercept (0.08 [95% CI = −0.10 to 0.20]) and slope (0.99 [95% CI = 0.92 to 1.11]) showed there is no constant or proportional error.

Conclusion:

Blood samples drawn in plastic serum tubes and plastic plasma tubes can be interchangeably used for determination of digoxin concentration.     

A more rational approach to the problem of an elastoplastic thick-walled cylinder

A new incremental theory has been developed for solving the problem of partially yielded thick-walled cylinders. Incremental stresses and strains are directly used as variables, hence numerical differentiation in the evaluation of stresses and strains is not required. The stresses and strains in all principal directions can be computed at the same time from governing equations for each increment of loading. Since the consideration of loading history is involved, the present theory is particularly suitable for predicting stress and strain distribution of a thick-walled cylinder subjected to nonproportionate loading.     

An interpretative model from the elasticity theory to explore knowledge integration in new product development

This paper presents a conceptual model to explore the knowledge integration (KI) practices of internal and external company actors involved in the New Product Development (NPD) process of the aerospace industry. The model is based on the linkage of elasticity principles, particularly Hooke’s Law, to Knowledge Management theory. KI practices are considered as a force pushing the NPD process and are metaphorically described as the spring addressed by Hooke’s law. The integration of the knowledge of internal and external company actors impacts NPD, reducing the dimensions of the whole process, in terms of phases, through the application of the concurrent engineering approach. The whole NPD process is improved in terms of the reduction of uncertainty and complexity, and with an ‘integrated energy’ that sustains the pressure of the fast-changing competitive environment. The model is explored to provide an interpretation of the conceptualisation phase of a new aerospace product development process. Qualitative data were collected and analysed. Insights regarding the applications of the model and the theoretical implications are also provided for applications in other industries.     

Some extensions of elementary plasticity theory

A detailed investigation is presented of yield or loading criteria, for work hardening materials, which lead to constant strain ratios under increasing stress when stress ratios are maintained constant. The experimenter is given a choice of incremental stress-strain theories with which results of simple or complicated combined loading tests may be correlated. These theories are dealt with in order of increasing complexity and, at the same time, increasing capacity to represent experimentally established phenomena.The objective is the use of the mathematically simplest theory which will provide the desired flexibility in the analysis of experimental data.Loading functions of isotropic as well as anisotropic types are examined, among them those depending explicitly on stress alone and those depending on both stress and plastic strain. In the latter cases only those functions are investigated in which plastic strain appears to the first order. The predicted results of some basic tests are examined for several loading criteria.     

The compound cylinder and the strength problem

A general discussion is given of the effects of various strength theories on the design of compound cylinders composed of as many as four tubes. Departing from the usual practice in problems of this type, the more modern theories of strength are included.The problem considered is limited to simultaneous, yielding in all component tubes of the cylinder under the action of bore pressure. In addition, new short design procedures employing graphical means are discussed which will considerably reduce the time ordinarily required in such calculations. The methods used are flexible since component tubes of different materials following different strength theories can be treated as easily as cylinders composed of tubes of one material.     

散体材料桩复合地基桩土应力应变关系研究

根据桩土变形连续及协调条件,采用土力学及弹性力学理论分析了散体材料桩复合地基在鼓胀变形情况下桩与桩间土的应力-应变关系,并推导出当桩周土体达到极限平衡状态时的单桩极限承载力及复合地基极限承载力的计算公式。经工程实例验证,计算值与实测值基本吻合。     

沉管灌注筒桩施工挤土效应分析与比较

简单介绍了沉管灌注筒桩及其沉桩施工工艺;假定沉管灌注筒桩沉桩时的挤土过程,是一个有初始孔径的圆柱形孔扩张过程,初始孔径等于筒桩内径,最终孔径等于筒桩外径,应用圆孔扩张理论进行弹塑性分析,得出应力场、塑性区半径、超静孔隙水压力等解析表达式,并通过与普通沉管灌注桩或预制实心桩挤土效应进行了比较,得出筒桩施工挤土效应远远小于普通沉管灌注桩或预制实心桩的结论,从施工挤土效应这个侧面揭示沉管灌注筒桩的优越性。     

论我国生态文明法制建设的三个着力点——基于马克思物质变换与断裂理论的思考

要全面推进依法治国,建设中国特色社会主义法治体系,建设社会主义法治国家,离不开生态文明法制建设。我国生态文明法制建设,应遵循马克思的物质变换及其断裂思想,坚持我国生态文明法制建设的三个着力点：生态文明法制建设要有利于人与自然关系的和谐发展、要符合社会和自然发展规律的要求、要做到有法可依和有法必依及执法必严。     

A probabilistic approach to polycrystalline plasticity part II: applications

Using our constitutive theory for polycrystalline plasticity, we have calculated characteristic yield conditions for several sample materials in which the dependence of the dislocation velocity on stress is given by an empirical power function. The shape of the yield surfaces for these materials varies resembling that of von Mises when the stress exponent is small and that of Tresca when the exponent is large. Additional examples illustrate the ability of the proposed theory to model such phenomena as the development of anisotropy during plastic deformation, material hardening and softening, the occurrence of upper and lower yield points, and a Bauschinger effect.     

离心钢管混凝土弯扭组合作用承载力三维数值相关分析

通过三维有限元模型来模拟现场试验及结构在工程实际中的情况,对离心钢管混凝土结构在弯扭组合作用下的力学性能进行了全过程的分析;并将计算值与试验值进行了对比,发现两者的吻合程度很好。在此基础上对该结构在承受弯扭组合作用下的弹塑性变形性状,和结构强度与刚度的非线性变化机理进行了分析。提出了离心钢管混凝土在弯扭组合下的弹性极限承载力相关方程,为工程设计和应用提供了依据。也为进一步对该结构在复杂应力状态下的力学性状的三维模拟分析提供了参照依据。     

一种模拟液化后的砂土在高孔压比状态下流动特性的试验方法研究

根据流体力学中的绕球定常黏性流动理论,在传统振动台试验的基础上,设计了一套模拟液化砂土高孔压比状态下流动特性的试验装置,在装有与氯化钠溶液混合的塑料砂的模型箱中埋入可以竖直滑动的有机玻璃半球,半球在其中竖直运动时可以模拟出半球在液化砂土中的运动,可以观察半球运动过程中塑料砂颗粒的运动特性。试验结果表明,本方法可以有效地做到模拟砂土液化后的力学状态,并且性质稳定,可以较好地获得砂土液化后的流动特性。     

湖北省第十届大学生运动会健美操比赛情况的分析

作者运用文献资料法、问卷调查法、对比分析法、访谈法等研究方法,对湖北省第十届大学生健美操比赛的参赛学校情况、比赛成绩等进行分析,探讨我省高校健美操运动的发展状况以及存在的主要问题,为该项活动更好地开展与普及提供一定的理论依据。     

基于哈肯模型的城市再生资源系统演化机制研究

城市再生资源的利用已成为世界各国谋求可持续发展的重要课题.城市再生资源系统演化机制是探索城市再生资源发展规律的一个重要途径.本文从城市再生资源系统的演化机理出发,首先分析了城市再生资源系统的内涵与理论演进方式,然后运用自组织理论中的哈肯模型,建立城市再生资源系统的演化方程,并以中国的19个省市区为样本进行了实证研究,结果表明反映经济效益的废旧材料回收加工业的利润是城市再生资源系统演化的序参量,最后对城市再生资源系统的演化机制进行了分析,为探索我国城市再生资源系统的发展规律提供理论参考.     

Yield loci around fiber inclusions

An analysis of the plastic enclaves developed around the end points of rigid fiber inclusions embedded in an elastic plate is undertaken. The plate is subjected to a uniform uniaxial stress at any angle of inclination with the axis of the fiber. It is assumed that the material of the plate is elastic-perfectly plastic and that the deformations are small. A singular solution of the stress field in the vicinity of the end points of the fiber is used in conjunction with the Mises yield criterion to obtain the radius of the plastic zone under conditions of plane strain and generalized plane stress. The dependence of the size and shape of the plastic deformation on the orientation of the fiber, the Poisson's ratio of the plate and the state of stress (plane strain or generalized plane stress) is established.     

The use of S-Monovette is effective to reduce the burden of hemolysis in a large urban emergency department

Background

Due to the high prevalence of hemolysis in specimens received from the emergency department (ED), several strategies have been proposed to improve sample quality, but none of these seem effective to overcome the problem. In a preliminary study we showed that the use of S-Monovette blood collection system was effective to lower the risk of hemolysis in venous blood samples collected from intravenous catheters. This study was hence aimed to verify whether the replacement of a conventional vacuum system with S-Monovette may be effective to reduce the burden of hemolysis in the daily practice of a large urban ED.

Materials and methods

The study was divided in two observational periods of 4 months each. In the former period, blood was collected from intravenous catheters using BD Vacutainer SST II Plus plastic serum tubes, whereas in the latter period the blood was drawn from intravenous catheters using S-Monovette blood tubes in aspiration mode. Sample hemolysis was automatically assessed in all serum samples by photometrical measurement.

Results

The total number of hemolysed serum specimens was 624/14155 (4.41%) in the first phase of the study, and 342/13319 (2.57%) in the second phase of the study (P < 0.001).

Conclusion

Results of our study confirm that the introduction of the Sarstedt S-Monovette blood tubes has reduced the hemolysis rate in the emergency department compared to the previously used BD Vacutainer® SST II Plus plastic serum tubes.Key words: preanalytical phase, hemolysis, blood specimen collection, catheter, emergency department     

湖北省第十届大学生运动会健美操比赛情况的分析

作者运用文献资料法、问卷调查法、对比分析法、访谈法等研究方法,对湖北省第十届大学生健美操比赛的参赛学校情况、比赛成绩等进行分析,探讨我省高校健美操运动的发展状况以及存在的主要问题,为该项活动更好地开展与普及提供一定的理论依据。     

影响橄榄石集合体蠕变性质物化因素的研究进展

综述了高温高压条件下岩石和矿物流变性的实验研究结果 ,总结了影响橄榄石集合体流变性能的各种物理和化学因素 .岩石和矿物在高温高压条件下变形的微观机制主要有 2种 :扩散蠕变和位错蠕变 .橄榄石集合体在扩散蠕变机制作用下 ,应变率 ε和差应力之间的关系为线性 ;在位错蠕变机制作用下 ,差应力指数n约等于 3.在相同差应力作用下 ,温度、熔融组分与橄榄石集合体的应变率是正相关的 .含水条件下 ,橄榄石集合体的强度显著降低 .颗粒度对差应力和应变率的影响比较复杂 ,低应变率和小颗粒度对应的差应力指数约等于 1 ;高应变率和粗糙颗粒度时 ,n为 3左右 .