On numerical analysis of damage evolution in cyclic elastic-plastic crack growth problems

Structures subjected to severe cyclic loading may fail due to low cycle fatigue. During the latter part of the fatigue life the crack growth rate may increase due to crack growth from static failure modes. This was investigated numerically by Skallerud and Zhang ( Int. J. Solids Struct. 34, 3141–3161, 1997) for a butt-welded plate with a circular crack growing from the centre of the weld. The weld material was slightly overmatching, and for simplicity, base material properties were employed in the finite element model. The predicted crack growth rate was significantly underpredicted in the early part of crack growth. In the present investigation, more detailed material modelling was used, and some metallurgical aspects were addressed. The fatigue part of the crack growth was determined by using the computed cyclic J -integral, and the static mode crack growth from ductile tearing is determined from computations accounting for void nucleation/growth/coalescence by means of a modified Gurson–Tvergaard model.     

Life cycle cost analysis of HPVT air collector under different Indian climatic conditions

In this communication, a study is carried out to evaluate an annual thermal and exergy efficiency of a hybrid photovoltaic thermal (HPVT) air collector for different Indian climate conditions, of Srinagar, Mumbai, Jodhpur, New Delhi and Banglore. The study has been based on electrical, thermal and exergy output of the HPVT air collector. Further, the life cycle analysis in terms of cost/kWh has been carried out. The main focus of the study is to see the effect of interest rate, life of the HPVT air collector, subsidy, etc. on the cost/kWh HPVT air collector. A comparison is made keeping in view the energy matrices. The study reveals that (i) annual thermal and electrical efficiency decreases with increase in solar radiation and (ii) the cost/kWh is higher in case of exergy when compared with cost/kWh on the basis of thermal energy for all climate conditions. The cost/kWh for climate conditions of Jodhpur is most economical.     

鄂尔多斯盆地姬塬地区三角洲前缘储层砂体成因分析

鄂尔多斯盆地姬塬地区延长组三角洲前缘是主要的油气储集带,为了探讨该地区储层砂体成因,文章将储层砂体类型分为六种：截削式河道、完整式河道、叠加河口坝、下残坝上河、完整坝上河和上残坝上河砂体.利用短期基准面旋回原理将这六种砂体的短期基准面旋回划分三大类六亚类,并对每一亚类砂体成因进行了分析.分析表明,砂体成因明显受基准面升降、可容纳空间和沉积物补给量比值的共同控制.最后,讨论了储层砂体分布规律并建立了该地区砂体成因分布模式.对砂体成因的细致刻画不仅可以提高该地区储层预测的精度,而且对今后的勘探和开发具有一定的指导意义.     

高分辨率层序地层学的应用——以鄂尔多斯盆地榆林长北气田山西组2段为例

以高分辨率层序地层学原理为指导,利用测井、钻井和野外露头剖面等资料,对鄂尔多斯盆地榆林长北气田山西组2段不同级次基准面旋回进行了详细划分,将山西组2段划分为1个长期、2个中期和5个短期基准面旋回.短期基准面旋回细分为两大类5种结构;中期基准面细分为两大类3种结构;长期基准面旋回为不完全对称型结构,区域分布较稳定.分析了不同级别的基准面旋回叠加式样与沉积相展布、演化规律之间的关系,中期基准面旋回上升半旋回开始阶段是辫状河三角洲河道砂体连续叠置形成巨厚砂体时期,洪泛面期及下降半旋回为细粒沉积物发育期.连续叠置的主水道和分支水道砂体形成了有利储层发育区,水下分流河道砂体与河口坝砂体构成了较好储层发育区.     

Life cycle energy of single landed houses in Indonesia

Building enclosures contribute 10–50% of the total building cost and 14–17% of the total material mass. The direct as well as indirect influence of the enclosure materials plays an important role in the building life cycle energy. Single landed houses, the typical houses in Indonesia, have been chosen for this study. The life cycle energy of the house enclosures and energy consumed during their life spans shows intriguing results. The initial embodied energy of typical brick and clay roof enclosures is 45 GJ compared to the other typical walls and roof material (cement based) which is 46 GJ. However, over the 40 years life span of the houses, the clay based ones have a better energy performance than the cement based ones, 692 GJ versus 733 GJ, respectively. The material selection during the design phase is thus crucial since the buildings have at least 40–50 years’ life span.     

Catalytic activity of polymer-bound Ru(III)-EDTA complex

Chloromethylated styrene-divinylbenzene copolymer was chemically modified with ethylenediaminetetraacetic acid ligand. Catalytically active polymer containing Ru(III) moieties were synthesized from this polymeric ligand. They were characterized using FTIR, UV-vis, SEM, ESR and TGA. Other physico-chemical properties such as bulk density, surface area, moisture content and swelling behaviour in different solvents were also studied. The polymer bound complex was used to study hydrogenation of 1-hexene ton-hexane under mild conditions. Influence of [1-hexene], [catalyst], temperature and nature of the solvent on the rate of the reaction was investigated. A rate expression is proposed based on the observed initial rate data. Recycling efficiency of the catalyst has also been studied.     

Thermal design of a laboratory—scale SO3 decomposer for nuclear hydrogen production

Designing of a sulfur trioxide decomposer is one of the main technical challenges in the development of a nuclear hydrogen production system. Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer to withstand the severe operating conditions. In this design, the hot gas side is equipped with printed circuit-type heat exchangers (PCHE), and the process gas side is equipped with plate fin-type heat exchangers (PFHE). In this study, the sensitivity analysis is performed to estimate the effects of the various factors on the thermal design of a sulfur trioxide decomposer for its performance test in a small-scale gas loop. The principal factors affecting the decomposer's thermal design are categorized into four groups: rate constants, geometrical parameters, heat transfer parameters, and operating conditions. Our results indicate that the rate constant of the catalyzed reaction and the decomposer retention time are the most important factors dictating the thermo-chemical behavior of the sulfur trioxide decomposer. The information obtained from this analysis will serve to guide the manufacture and operation of this laboratory-scale decomposer.     

有串联间隙金属氧化物避雷器动作负载特性分析

带串联间隙金属氧化物避雷器动作负载试验频繁失败的原因和如何正确选取电阻片整体参数一直是制造厂和用户关注的问题。笔者通过对 1 996年全国避雷器统检情况及 GB1 1 0 3— 2 0 0 0标准验证试验的详细分析和反复研究性试验 ,对带串联间隙金属氧化物避雷器动作负载试验失败原因进行了分析并提出了改进建议     

水资源可持续利用与水工业

从水的自然循环和社会循环的相互关系，论述了水环境污染产生的原因及对水资源可持续利用的影响，并针对水资源危机和水资源可持续利用提出了对策意见，以水的社会循环为研究对象，给水排水已从过去的城市基础设施发展成为一个新兴产业－水工业。文中对其前景作了简要阐述。