Effect of heterogeneity of materials and heat cycles on diffusion of hydrogen as a factor of the risk of development of hydrogen degradation of metals

Conclusions The analysis results show that in the presence of hydrogen the nonstationary nature of the thermal effects (heat changes, thermal cycles) in the presence of heterogeneities may on its own be a factor causing a high risk of hydrogen degradation and may be of the implicit type (hidden). The degree of risk depends, in particular, on the kinetics of thermal processes. These defects must be taken into account by estimating the properties of materials after the effect of hydrogen and solving the problems of ensuring safety of structures both in the design stage and controlling efficiency and in determining the optimum (permissible) operating conditions, and also in determining the residual service life. In certain cases the conditions of transition of thermal processes may be of controlling importance for the efficiency of materials in structures.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 6, pp. 7–20, November–December, 1992.     

输入估计值的测量不确定度评定

本文所介绍的与1993年由ISO等7个国际组织联合发表的《测量不确定表示指南》（简称《指南》）完全一致，只是指南上的实用于物理测量的绝大多数领域，而本文介绍的仅适用于校准实验的测量。同时本文主要侧重于对输入估计值的A类测量不确定度和B类测量不确定度的评定的介绍，为输出估计值的测量不确定度评定奠定了良好的基础。     

水线震荡对斜拉桥拉索风雨激振稳定性的作用

从理论和试验两个方面研究了水线震荡对斜拉桥拉索风雨激振稳定性的作用。建立了拉索和水线的运动方程，应用李雅普诺夫函数给出了水线不平衡角的判别公式。设计了一种新型的带有可运动人工水线的拉索模型，并进行了风洞试验。理论和试验结果表明，水线震荡是导致拉索风雨激振具有较大不稳定范围的主要原因。试验结果证明了理论模型和分析的结果是正确的。     

粗氩冷凝器堵塞故障的处理

因为进分子筛吸附器的空气温度偏高,分子筛吸附器出口空气中二氧化碳含量超标,二氧化碳在粗氩冷凝器换热通道内积聚,造成粗氩冷凝器堵塞,制氩系统停运。介绍粗氩冷凝器堵塞时的参数变化情况和采取的加温措施。     

基于管道声模态的消声器传递损失计算

传递损失是评价消声器声学性能的一个重要指标。提出了一种方法—管道声模态法代替传统方法估算传递损失。对进出口截面积较小的消声器进行计算和检验,与传统方法比较,结果基本吻合,且过程简单,提高传递损失的计算效率。对进出口截面积较大的消声器,中高频段由于大量高次波的出现,传统方法失效;但低频段管中声波以平面波为主,其结果与传统法一致。因此可以采用管道声模态法快速估算传递损失。     

Evaluation of vibration-induced stresses in teeth of rotor disks of compressors of gas-turbine engines

We show that loads induced in turbine blades by vibration make a significant contribution to the dynamic stressed state of the teeth of compressor disks. The dynamic stresses formed in the teeth of the investigated blade wheels can be as high as 42% of the stresses induced in the blades. Together with fretting corrosion, static stresses, and other factors, this may lead to initiation and propagation of cracks in teeth and, as a final result, their fracture.     

Two methods of investigation of the influence of hydrogen on the propagation rate of a crack and behavior of fracture of high-strength steels

We present two methods for the investigation of the influence of hydrogen on the propagation rate of a crack and behavior of fracture of high-strength steels. The method for investigation of the influence of electrolytic hydrogenation on a subcritical growth of a crack in high-strength steels is based on the use of simple beam specimens of a certain geometry and on the application of lateral loading in such a way that the stress intensity factor can be constant at the tip of a preliminary induced crack. The method is of great importance for the performance of comparative experiments in evaluating the influence of active media and structural anisotropy of specimens made of high-strength steels with limited sizes on their corrosion crack resistance. Typical examples of the application of the method to investigation of the role of electrolytic hydrogenation in subcritical propagation of cracks and their branching in highstrength steels are given. The method for investigation of heat release under strain and fracture of hydrogenated specimens involves the use of microcalorimetric devices, which allow one to study the influence of hydrogenation on peculiarities of the kinetics of elastic and plastic strains of high-strength steels. We illustrate the efficiency of the method proposed by plotting the “load-elongation” curves and corresponding (in time) characteristics of heat release power in the process of strain and fracture of specimens made of a high-strength steel. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 34, No. 4, pp. 113–120, July–August, 1998     

Solution of the Problem of Identification of the Process of Heating of Cylindrically Shaped Bodies in Industrial Furnaces

The values of the coefficients of heat exchange by convection and radiation in the case of heating of cylindrically shaped billets in industrial furnaces are determined. The algorithm and the composition of software for the problem under solution are described. The results of testing and recommendations on assignment of the errors of computations of the coordinates of a minimum from the viewpoint of decrease in the calculation time are given.     

一起主换热器液氧通道堵塞故障分析与处理

因为液氧通道存在部分堵塞,35000m^3／h空分设备主换热器存在明显的偏流现象,扒砂割管处理后,消除了偏流现象。文章简介了主换热器的结构和流程,介绍偏流存在时主换热器中部温度异常现象和原因分析过程,阐述了停车扒砂处理故障的过程和效果。     

A Review of Analysis of Dynamic Response in Design of Experiments

Systems with dynamic characteristics have gained increasing attention of both researchers and engineers in industry in recent years. The purpose of this article is to provide an overview of investigations on what might be called dynamic response in experimental design, so as to facilitate further research in this area. We briefly review the development of research on dynamic problems in diverse fields such as statistical quality control, biostatistics, experimental design and repeated measurements. Discussions in the past are specially sorted out on the definition and classification of dynamic response problems as encountered in general experimental design and robust design, and various perspectives of system types and response types. Four categories of modelling techniques in classical experimental design are summarized from the literature according to distinct application conditions; this would provide a useful basis for future investigations. Copyright © 2014 John Wiley & Sons, Ltd.     

Evaluation of solid dispersions of Clofazimine

Clofazimine (CLF) was formulated with polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) as a solid solid dispersion (SSD) to increase the aqueous solubility and dissolution rate of the drug. Different molecular weights of PEG (1500, 4000, 6000, and 9000 Da) and PVP (14,000 and 44,000 Da) were used in different drug:carrier weight ratios (1:1, 1:5, and 1:9) and their effect on the dissolution performance of the drug was evaluated in USP Type 2 apparatus using 0.1 N HCl medium. The dissolution rate was compared with corresponding physical mixtures, a currently marketed soft gelatin capsule product, and free CLF. The effect of different methods of preparation (solvent/melt) on the dissolution rate of CLF was evaluated for PEG solid dispersions. Saturation solubility and phase solubility studies were carried out to indicate drug:carrier interactions in liquid state. Infrared (IR) spectroscopy and X-ray diffraction (XRD) were used to indicate drug:carrier interactions in solid state. Improvement in the drug dissolution rate was observed in solid dispersion formulations as compared to the physical mixtures. The dissolution rate improved with the decreasing weight fraction of the drug in the formulation. Polyvinyl pyrrolidone solid dispersion systems gave a better drug release profile as compared to the corresponding PEG solid dispersions. The effect of molecular weight of the PEG polymers did not follow a definite trend, while PVP 14,000 gave a better dissolution profile as compared to PVP 44,000. Improvement in saturation solubility of the drug in the solid dispersion systems was noted in all cases. Further, IR spectroscopy indicated drug:carrier interactions in solid state in one case and XRD indicated reduction in the crystallinity of CLF in another. It was concluded that solid-dispersion formulations of Clofazimine can be used to design a solid dosage form of the drug, which would have significant advantages over the currently marketed soft gelatin capsule dosage form.     

秒表检定的测量不确定度评定

介绍了用标准时间间隔发生器检定秒表时,测量结果不确定度分析和评定过程;讨论了测量不确定度的几个主要来源;通过一组实例,给出了秒表检定不确定度的分析和评定结果,该过程和结论可应用在对于计量标准进行相应指标的不确定度分析上,也可用于估计秒表检定本身的不确定度。     

Quantitation of Activity of Alkyl Ester Prodrugs of Ibuprofen

ABSTRACT

A quantitative relationship has been derived for the physicochemical properties and pharmacological activity of alkyl ester prodrugs of ibuprofen. A comprehensive study consisting of aqueous solubility, octanol-water partition coefficient, hydrolysis kinetics in aqueous buffer (pH 7.4) & human plasma, ulcerogenic studies, anti-inflammatory and analgesic activity was carried on alkyl ester prodrugs of ibuprofen. n-Propyl and n-butyl esters offered significant improvement in oral delivery of ibuprofen in terms of reduced gastroulcerogenicity and maintenance of pharmacological activity.     

Effect of addition of carbon on magnetic properties of sputter-deposited CoCr film

The addition of carbon changes Ms, Hkeff and Hc(perp) of sputter-deposited CoCr films: Ms is always increased, while Hkeff and Hc(perp) are either increased or decreased by the addition of up to 0.32 at% carbon. How the substrate temperature and the Cr content in the film influence the effect of added carbon is investigated. Higher substrate temperature tends to stimulate the increase in Ms caused by the addition of carbon. A higher substrate temperature and higher Cr content tend to stimulate the increase in Hkeff and Hc(perp) and to prevent the decrease in Hkeff and Hc(perp) caused by the addition of carbon. The increase in Ms with the addition of carbon seems to be caused by an increase in the degree of compositional segregation. The increase and decrease in Hkeff may be attributed to an increase and decrease in Ku, respectively. The increase in Hc(perp) caused by the addition of carbon is probably due to the increase in Ku and/or to the refinement of the magnetic domain. The decrease in Hc(perp) may be attributed to the decrease in Ku even though the magnetic domain is refined.     

计数法测量采集速率的不确定度评价

介绍了用标准周期计数法评价线性测量系统采集速率时，测量结果的不确定度分析和评价过程；讨论了影响评价结果不确定度的几个主要来源；给出了减小采集速率评价不确定度的主要措施，通过一组实例，给出了采集速率不确定度分析和评价结果，该过程及结论可应用在对于计量标准进行相应指标的不确定度分析上，也可用于估计采集速率指标本身的不确定度。     

Linearization of families of germs of hyperbolic vector fields

In this article, we develop some techniques to linearize families of smooth vector fields in a neighbourhood of a hyperbolic equilibrium point. In particular, we present the linearizing conjugacy in an explicit way and describe the smoothness of the conjugacy in terms of the eigenvalues of the vector fields.     

Investigations of deformation of FGM

FGM are marked by a heterogeneous composition changing continuously. Therefore, it must be considered while deformation that different material ranges show different deformation behaviour and that the overall deformation is inhomogeneous. For this reason the graded material was subdivided into a finite number of ranges for the simulation of the deformation behaviour. Homogeneous material behaviour is assumed in these ranges. The yield strengths of the respective homogeneous materials are determined experimentally and then applied as material parameters in the simulation. A simple upsetting of a cylindrical specimen at constant temperature and deformation rate was calculated as an example. The results of the simulation show that, as expected, the material flow is marked differently in various material ranges due to the differing yield strength. This is confirmed by experimental investigations. Differences in the results of simulation and experiments in particular occur in the case of the direct comparison of the geometrical dimensions. This is mainly explained by differing initial microstructures. The comparison of the compression forces shows good agreement between simulation and experiment.     

Strain mapping by measurement of the degree of polarization of photoluminescence

A technique is described for the simultaneous measurement of the difference in the normal components of strain and of the shear strain in luminescent III-V material from the degree of polarization (DOP) of photoluminescence. This technique for the measurement of shear strain and of the difference in the normal components of strain in InP was calibrated by applying known external loads on the bars of InP with V grooves etched into the bars and by fitting the experimental results to two-dimensional finite-element simulations. Fits to the difference in the normal components of strain (as opposed to stress) yielded significantly smaller residues. On this basis we conclude that the DOP of luminescence is proportional to the difference in the normal components of strain.     

聚丁内酰胺的生物降解性研究进展

目的 介绍聚丁内酰胺(Polybutyrolactam,PA4)的生物降解性研究现状,综述聚丁内酰胺及其衍生物在海洋、土壤、堆肥等自然环境中的生物降解速率及降解机制,为聚丁内酰胺的改性和应用研究提供指导.方法 采用分类总结的方法,对比聚丁内酰胺及其衍生物在不同环境下的降解行为,阐述目前关于其降解机制的研究进展.结论 聚丁内酰胺可在自然环境中短期内降解,其优异的生物降解性与亲水性有关,同时自然环境中长期存在的某些菌群能够分泌胞外酶水解酰胺键,使得聚丁内酰胺可在自然环境中快速降解.结构改性对聚丁内酰胺的降解速率具有一定影响,探究聚丁内酰胺改性后生物降解性的变化,有助于开拓控制其降解速率的新思路.聚丁内酰胺具有极高的气体阻隔性和出色的力学性能,未来作为可降解材料在食品包装方面应用具有极高的应用前景,通过合适的改性手段实现PA4热塑加工,并保留PA4良好的生物降解性,明确环境微生物对PA4及其改性产物的代谢和降解途径,也是未来研究的难点和热点.