Indicators for inspection and maintenance planning of concrete structures

Based on an idea introduced by Benjamin and Cornell (1970. Probability, statistics and decision for civil engineers. New York: McGaw Hill) and previous works by the authors it is demonstrated how condition indicators may be formulated for the general purpose of quality control and for assessment and inspection planning in particular. The formulation facilitates quality control based on sampling of indirect information about the condition of the considered components. This allows for a Bayesian formulation of the indicators whereby the experience and expertise of the inspection personnel may be fully utilized and consistently updated as frequentistic information is collected. The approach is illustrated on an example considering a concrete structure subject to corrosion. It is shown how half-cell potential measurements may be utilized to update the probability of excessive repair after 50 years. Furthermore in the same example it is shown how the concept of condition indicators might be applied to develop a cost optimal maintenance strategy composed of preventive and corrective repair measures.     

Preparation and characterization of chitosan‐based dispersions

Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry     

The solution of the inverse problem of gravitational potential using a set of measurements of different field elements

A numerical solution of the inverse problem of the gravitational field at a single point is obtained using six field elements for a point, a spherical cap, a differential spherical sector and a vertical segment. In the system of six equations obtained, the unknowns are the mass of the body, the depth of its center, and the second, third, and fourth degree moments. The accuracy of the solution of this system is ten times higher than when using three field elements. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 3–8, May, 2007.     

郯庐断裂带含油气性研究

郯庐断裂带是中国东部一条巨型断裂构造带,该文从其基本构造特征入手,分析了它的几何学、运动学和动力学特征,并进一步研究其含油气特点,认为:a)郯庐断裂带对中国东部诸多中新生代含油气盆地的形成及演化有重要的控制作用,不同演化阶段产生并控制了不同的沉积盆地(如松辽盆地和渤海湾盆地);b)郯庐断裂带对油气藏的形成及演化有重要的控制作用,不仅控制盆地烃源岩的发育、基本的储集层和盖层条件,以及圈闭的形成等等,而且对油气的生成、运移及聚集成藏、大中型油气田的形成及分布等有重要的控制作用.      

复杂断块油藏剩余油分布及配套挖潜对策

复杂断块油藏开发后期剩余油分散而难以识别，且其分布受多种因素的控制。在大港油区的港东开发区，根据以纵向1118个时间地层单元为对象的精细油藏描述，提出3类剩余油潜力：①已动用油层，即断层与微构造控制、注采井网不完善、层间非均质性、平面低渗透相带、层内渗流屏障、注采滞留区、边底水锥进等因素形成的剩余油；②新层，即以往未发现的低电阻油层和新发现油砂体；③滚动扩边。在潜力认识的基础上，以单砂体或流动单元为挖潜调整对象，在潜力富集区钻新井、更新井，改变非主力层的驱动方式，重组层系、井网，改变液流方向和间歇注水，并对潜力区配套实施补层、提液、压裂防砂、重复射孔、深度调剖等措施。港东开发区复杂断块油藏实施配套挖潜措施后，提高了高含水期的开发效益与水平。图1参17     

Preparation of clean coal by flotation following ultra fine liberation

This paper reports the results of current fundamental research at the Department of Process Engineering, University of Miskolc on the processing of clean coal from Mecsek bituminous coal, Southern Hungary. The theoretical possibility of the separation of different petrographic components was proven experimentally and their liberation degree was determined based on the petrographic composition, flotation kinetic study of isolated components (groups of components), scanning electron microscopy and microprobe analyses. The mill with stirred ball media was chosen for the ultra-fine liberation of the coal components. It was revealed that along with the liberation of coal components, their surface oxidation and spontaneous agglomeration, entrapping the mineral impurities take place in ultra-fine grinding. This paper discusses the interfacial phenomena occurring in the ultra-fine grinding process and their influence on the flotation. The concept for the advanced preparation of clean coal was developed, tested and proved. The main steps of this concept are the ultra-fine liberation in the stirred-media mill, the de-agglomeration of flocs spontaneously formed during the ultra-fine grinding and the induced (hydrophobic) flocculation with the following two-step flotation in a flotation column.     

油藏能量势及应用前景

建立了油藏能量势的定义，阐述了其物理意义。油藏能量势好地揭示油藏开发过程中流体运动的本质，运用该定义能较好地解释油藏开发过程中的水窜、气窜、间歇注水和脉冲注水、注水井调剖和注氮气采油技术机理，对指导油藏勘探、开发具有一定的意义。     

老铁矿寻求新发展

云浮市铁矿是个老矿山，在资源减少、设备陈旧、成本增加和效益骤降等困境中，坚持走“一业为主，多种经营”的路子，在革新挖潜的同时，拓展工、商、贸及房地产业等多元化经营，使老矿山旧貌换新颜，多种经营收益已超过矿山总收益的30％。     

Electrochemical Aspects of Electroosmotic Dewatering of Clay Suspensions

An attempt is made to elucidate the electrochemical aspects of the electroosmotic dewatering (EOD) of clays as reported in some recent work, especially that on interrupted DC power electroosmotic dewatering published by Rabie, Mujumdar and Weber (2). These authors showed that the dewatering by EOD stops after the DC power has been on for several minutes or hours; on interruption of their power and on short-circuiting of the electrodes, conditions can be created again for some further dewatering by DC power EOD. This discovery, of Rabie et al. is interpreted as a fuel cell effect and it is shown that it affords clues to several other electrochemical strategies for the possible enhancement of the efficiency of the EOD by DC power.

Further, the open circuit potentials observed by Rabie et al. (2) on the interruption of DC power are given an electrochemical interpretation which leads to quantitative estimates in agreement with the experimental values.     

Preparation and Properties of Sintering Additives Coated Si3N4 from Heterogeneous Nucleation Processing

The sintering additives such as Al2O3 and /or Y2O3 were coated on the surfaces of Si3N4 particles via heterogeneous nucleation processing using a buffered pH solution as the precipitation reagent .They nucleated and grew only on the surfaces of Si3N4 and did not form sol particles in solution by TEM observation .The isoelectric point(IEP) of coated Si3N4 was different from that of as-received Si3N4.The IEP of Al(OH)3-coated Si3N4 occurred at pH8.4, which is close to that of alumina .When Al(OH)3-coated Si3N4 particles were coated with Y(OH)3,the IEP of coated Si3N4 powder shifted from pH8.4 to pH9.2 ,similar to that of yttria.In addition ,the rheological data showed that Al2O3 and /or Y2O3 coated Si3N4 suspension is nearly Newtonian and that added Si3N4 suspension shows a shear rate thinning behavior.