Rain erosion damage in brittle materials

In order to understand the processes involved in the high-velocity rain erosion of brittle materials the impact damage produced in soda-lime-silica glass by single and multiple jet impact was studied. The damage was quantified by measuring the post-impact strength of specimens. It is shown that the impact damage depends on the impact velocity, the number of impacts and the specimen dimensions. A new analysis for calculating the velocity dependence of jet/drop impact damage in brittle materials is presented. The model is based on Hertzian contact analysis and dynamic fracture mechanics and takes into account the statistical nature of the flaws in the specimen. A good qualitative agreement with experimental results is obtained.     

A simple method for measuring friction for spheres and cylinders

A method is given for determining the static coefficient of friction between a sphere or cylinder and a flat surface, or between two spheres or cylinders. This paper describes a simple approach for making such measurements and demonstrates that it produces acceptable values.     

冀中坳陷饶阳凹陷留西沙三段岩性油藏勘探思路

在已勘探多年的留西地区,遵循新的研究思路和工作方法,即"构造研究找背景、层序划分建(地层对比)格架、微相研究定(砂体)类型、成岩分析划(经济)界线、储层预测描砂体、综合分析建(成藏)模式、圈闭优选标井位、滚动研究扩成果",开展Es3低位体系域辫状河三角洲砂体岩性油藏勘探取得了重要突破,控制、预测两级石油地质储量达5000×104t。     

Identification of bacteria crucial to histamine accumulation in pacific mackerel during storage

Bacterial growth and histamine formation in Pacific mackerel during storage at 0, 4, 15, and 25 degrees C were monitored. To identify bacterial species contributing to histamine formation, several groups of bacteria were isolated by using selective media under temperatures corresponding to the various storage conditions. Initially, low counts of bacteria were found in the gill, skin, and intestine of fresh fish, and only weak histamine formers were found in the gill. Histamine was found in the muscle when fish were stored above 4 degrees C, and aerobic plate counts reached 10(6) CFU/g. When fish became unsuitable for human consumption by abusive storage, toxicological levels of histamine were always found. The highest level of histamine formed was 283 mg/100 g in 2 days. The optimum temperature for supporting growth of prolific histamine formers was 25 degrees C. The most prolific and prevalent histamine former was Morganella morganii, followed by Proteus vulgaris, both of which were isolated on violet red bile glucose (VRBG) agar. At 15 degrees C, a significant level of histamine was still produced in fish muscle, although prolific histamine formers were less frequently detected than at 25 degrees C. The isolates on thiosulfate citrate bile salts sucrose (TCBS) agar were weak histamine formers and identified as Vibrio parahaemolyticus and Vibrio alginolyticus. At 4 degrees C, less than 57.4 mg/100 g of histamine was found in fish stored for 14 days. Most isolates were natural bacterial flora in the marine environment and identified as weak histamine formers. At 0 degrees C, neither histamine former nor histamine production was detected up to 14 days of storage.     

An approximate compositional approach to the analysis of fluid queue networks

Fluid models have for some time been used to approximate stochastic networks with discrete state. These range from traditional ‘heavy traffic’ approximations to the recent advances in bio-chemical system models. Here we present a simple approximate compositional method for analysing a network of fluid queues with Markov-modulated input processes at equilibrium. The idea is to approximate the on/off process at the output of a queue by an n-state Markov chain that modulates its rate. This chain is parameterised by matching the moments of the resulting process with those of the busy period distribution of the queue. This process is then used, in turn, as a separate Markov-modulated on/off process that feeds downstream queue(s). The moments of the busy period are derived from an exact analytical model. Approximation using two- and three-state intermediate Markov processes are validated with respect to an exact model of a tandem pair of fluid queues — a generalisation of the single queue model. The analytical models used are rather simpler and more accessible, albeit less general, than previously published models, and are also included. The approximation method is applied to various fluid queue networks and the results are validated with respect to simulation. The results show the three-state model to yield excellent approximations for mean fluid levels, even under high load.     

从HSE检查规范入手，提高HSE管理水平

2007年中国石化浙江石油分公司在总部安环局和销售公司的直接领导下，从HSE检查规范入手，努力提高HSE管理水平，按照总部“严细实恒”的要求，在强化安全监督、人员培训、应急管理、未遂事故管理等方面开展工作；强“三基”、反“三违”、控制作业风险，克服了资源紧张，低库存运作所带来的经营困难和安全风险，战胜了历史上罕见的超强台风袭击，安全生产形势总体平稳，经济效益明显。     

ELASTOPLASTIC CONTACT BEHAVIOR AND SHAPE OPTIMIZATION OF DRILLPIPE THREAD

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EFFECT OF DRILLPIPE ROTATION ON BOREHOLE CLEANING FOR EXTENDED REACH WELL

Wellbore cleaning is a key technology for the Extended Reach Drilling (ERD). The success of drilling extended reach wells depends directly upon the quality of wellbore cleaning. The rotation of the drillpipe, and hydraulic and rheological parameters, are the key factors for wellbore cleaning. In this study, Computational Fluid Dynamics (CFD) is applied to simulate solid-liquid two-phase flows in wellbore annulus. The annual flow field with the presence of drillpipe rotation is described through analyzing various rotation conditions. The results indicate that the quasi-spiral flow is the main flow pattern for liquid-solid transport in the horizontal annulus. The influence of rotation on the cuttings transport is also investigated, as the rotation of drillpipe increases the disturbance of liquid to solid in annulus. As a result, the solid flow becomes favorable and the solid volume is reduced. Comparisons with previously published results are also performed to prove the importance of drillpipe rotation in the wellbore clearing for the ERD.     

Evolution of Annealing Twins in Sputtered Cu Films

The Monte Carlo Potts model with n-fold method was used to simulate grain structure evolution in thin Cu films according to energetic competition principles. Surface/interface, grain boundary, and strain energy factors were applied to determine grain growth and crystallographic texture evolution as a function of film thickness. Furthermore, annealing twins were simulated through specific criteria that arbitrarily insert twin grains into the structure through grain boundary energy considerations. Four different types of microstructures were observed experimentally and simulated by the Monte Carlo technique.