Matrix method to determine shift-register connections for delayed pseudorandom binary sequences

A practical method is described to determine the modulo-2 feedback shift-register connections for producing advanced (or delayed) versions of a pseudorandom binary sequence.     

Visualisation of mechanisms involved in Co2 injection and storage in hydrocarbon reservoirsand water-bearing aquifers

Storage of carbon dioxide (CO₂) in hydrocarbon reservoirs and saline aquifers is considered as one of the promising mitigation strategies to reduce the negative impact of this greenhouse gas. The static and dynamic behaviour of CO₂ in these storage sites which are located at various depths and geographical locations, affects the efficiency of this strategy. Understanding the impact of the conditions of these storage sites on mechanisms involved in CO₂ flow, displacement and trapping is also critical for the purpose of site selection and the design of CO₂ storage projects. In this paper we report the results of a series of CO₂ injection (CO₂I) flow visualisation (micromodel) experiments conducted using high-pressure transparent porous media representing various aquifer and depleted oil reservoirs storage conditions. The impact of pertinent parameters on the interaction between the stored CO₂ and the reservoir fluids were investigated. Both sub-critical and supercritical CO₂ were used to investigate the effect of pressure (depth) of the storage site on CO₂ trapping mechanisms. A faster CO₂ breakthrough (BT) was observed in the micromodel test simulating CO₂I into depleted oil reservoirs, compared to that into aquifers, reducing the sequestration capacity of the depleted oil reservoirs. Compared to the injection of supercritical CO₂, the BT of gaseous CO₂ happened faster, adversely affecting the CO₂ displacement performance. The results of these direct flow visualization experiments significantly improve our understanding of the complex mechanisms and interactions involved in CO₂I and storage in geological formations. This knowledge is essential for identifying storage conditions that would lead to maximising CO₂ storage capacity, for better understanding the ultimate fate of the stored CO₂ and the storage safety.     

Electrochemical investigation of galvanic corrosion between aluminum 7075 and glass fiber/epoxy composites modified with carbon nanotubes

We investigate whether the presence of carbon nanotubes in previously non-conductive composites may cause galvanic corrosion. We focus on aluminum 7075 alloy and glass fiber-reinforced polymers (GFRP), where the epoxy resin is modified with multi-walled carbon nanotubes (MWCNTs). Whole aluminum bars were bonded with MWCNT/GFRP in a co-cure, or were connected electrically with the composite through a galvanic cell.The investigation includes characterization of the treated and baseline epoxy resin, high humidity tests at room temperature, full immersion tests in an aggressive environment, and standard galvanic coupling tests in an aggressive environment.Results show that coupling MWCNT/GFRP samples with aluminum 7075 causes approximately doubled corrosion rate and mass loss rate compared to baseline GFRP samples. We envision that this work will impact the research community and indicate the need of careful coupling selection and careful surface treatment between nanomaterials and conventional materials, since the ability to monitor damage in situ is very desirable.     

Secondary hypertension: a practical diagnostic approach

Secondary hypertension is a relatively uncommon, potentially reversible condition for which physicians should maintain a high index of suspicion. When a patient is found to have elevated blood pressure, a through history should be obtained and a complete physical examination should be performed. Depending on the findings, additional screening and diagnostic studies may be necessary. The most common causes of secondary hypertension are renal parenchymal disease, renovascular disease, coarctation of the aorta, pheochromocytoma, primary hyperaldosteronism, thyroid dysfunction and Cushing's syndrome.     

企业项目管理：一个战略视角

迄今为止，人们已经从不同的角度对企业项目管理(enterprise project management，EPM)进行了研究，并把它看做是组织行为的一个独特的组成部分。有一种观点认为，EPM就是一种软件工具，有助于计划和实施组织内的所有项目。还有一种观点认为，EPM是指从一个中心点出发对项目进行选择、计划、控制和实施，从而严格确保所有的项目都指向单一元素。对于组织来说．这两种观点都不能说是错误的，但是大局圈(biggerpicture)将会有助千我们更好地理解EPM的全部潜力。     

Liquid Transport in a Coalescing Froth

A previous study (Ireland and Jameson, J. Colloid Interface Sci., 314 207‐213 (2007)) demonstrated that a “drift‐flux” model could describe liquid transport in a stable rising froth with added “wash water.” In the present study, a drift‐flux model was used to describe a rising coalescing froth. This model incorporated the effect of liquid released into the froth by coalescence. Vertical profiles of liquid fraction and bubble size were obtained in a laboratory cell; a novel technique was used for measuring bubbles deep within the cell. These data were consistent with the predictions of the drift‐flux model.