Analyses of Inclined Boreholes in Poroelastic Media

Solutions for the borehole problem based on Biot’s poroelasticity theory have shown that drilling through fluid saturated formations, gives rise to time-dependent stress and pore pressure fields in the vicinity of the borehole. As a natural consequence, borehole stability in such formations is of a time-dependent nature. However, existing analyses are based on two limiting cases viz., constant pore pressure and/or no flux boundary conditions at the borehole wall. Adding time dependency to the pore fluid boundary conditions can simulate realistic field conditions such as those observed during hydraulic fracturing, fluid injection or development of filter cake. Analytical solutions for inclined boreholes with time-dependent pore pressure and flux boundary conditions at the borehole wall are presented in this paper. Analysis is carried out for two special cases of the ramp-type pore pressure and linearly reducing flux boundary conditions. Analytical solutions are supplemented with asymptotic solutions for small and large time analysis. The effects of these conditions on stress concentrations near the borehole wall and their implications on borehole stability are examined in detail.     

Instability Conditions of Loose Sand in Plane Strain

When a loose sand specimen is loaded under an undrained condition, it may become unstable. The instability conditions may be specified by an instability line determined using undrained tests. However, the instability behavior of sand has seldom been studied under plane-strain conditions. Experimental data obtained under both triaxial and plane-strain conditions are presented in this paper to define the instability conditions of loose sand under plane-strain conditions. Using the state parameter, a unified relationship can be established between the normalized slope of instability line and the state parameters for both axisymmetric and plane-strain conditions. Using this relationship, the instability conditions established under axisymmetric conditions can also be used for plane-strain conditions.     

胶东地区金矿地质背景及金矿分布特征分析

我国胶东地区,矿物储备广泛,其中金矿的储备也是优于其他地区,胶东地区的金矿地质背景及金矿分布特征分析。本文介绍并分析了胶东地区的地层情况,以及由于此地区的地壳运动而使该地区的地质结构适用出矿和容矿。江东地区岩浆岩分布较为广泛,也为金矿的出产带来了有利条件,通过分析地质情况,对金矿的分布特征进行分析。     

冀东地区金属矿赋存特征及找矿浅析

本文对冀东石人沟金矿区域地质特征、矿床特征进行了充分论述,应用最新成矿理论和找矿方法对冀东地区的金属矿成矿地质条件、控矿因素、成矿规律进行了认真的研究探讨,总结了冀东地区区域成矿条件,并从中筛选控制矿床形成的重要条件,推测出石人沟地区成矿远景区。     

Flow Conditions of Undular Hydraulic Jumps in Horizontal Rectangular Channels

The flow conditions of undular jumps for fully developed inflow condition have been investigated systematically. If the inflow Froude number is larger than 1.2, an undular jump has lateral shock waves near the toe of the jump. For a narrow channel, the shock waves cross upstream of the first wave crest, and the flow conditions of undular jumps depend on the aspect ratio and the inflow Froude number. In contrast, for a wide channel the shock waves do not cross upstream of the first wave crest, and the flow conditions of undular jumps are independent of the aspect ratio. The flow conditions of undular jumps are classified by considering the cross position of the lateral shock waves and the inflow Froude number. Also, the hydraulic conditions for the formation of nonbreaking and breaking undular jumps are determined. The effect of the Reynolds number on undular-jump formations is discussed, and changes of the flow conditions with the Reynolds number are described.     

Behavior of the Working Fluid in Mechanized Support in Permafrost

This paper summarizes the results of an investigation of mechanized support under permafrost conditions. The present paper analyzes mechanized support behavior under subzero temperatures. The influence of cooling of the working fluid on support resistance is considered, and recommendations are given for efficient operation of mechanized complexes under those conditions. The laboratory experimental data are in good agreement with the results obtained from a field study.     

Video detection of problems in the melting of consumable electrodes in a vacuum arc furnace

Methods are proposed for the detection of problems in vacuum arc melting. Video cameras are mounted on the vacuum arc furnace in order to monitor the melting process. Usually, the automatic control system for the melting process only measures the quantities required for direct control. In some cases, those measurements do not permit the detection of specific nonstandard melting conditions. However, on the basis of the video images, the supervisor can identify and eliminate such problems. The video feed is divided into frames. Each frame is a matrix consisting of pixels. On the basis of the sum of pixels in the image, anomalous melting conditions may be determined. Algorithms are proposed for analysis of the video images so as to detect anomalous melting conditions.     

Two-Dimensional Analysis of Dam-Break Flow in Vertical Plane

This work presents numerical computations for the analysis of Dam-Break Flow using two-dimensional flow equations in a vertical plane. The numerical model uses the general approach of the simplified marker and cell method combined with the volume of fluid approach for the surface tracking. The time evolution of flow depth at the dam site and the evolution of the pressure distribution are investigated for both wet and dry bed conditions. The effect of the initially nonhydrostatic state on the long term surface profile and wave velocity are studied. These long term effects are found to be marginal in the case of wet-bed conditions, but are significant in dry-bed conditions. The dry-bed tip velocity immediately after the dam break, computed numerically, compares well with analytical results published previously. The time taken to obtain a constant flow depth at the dam site increases with decreasing initial depth ratio. The numerical result for this time elapse for dry-bed conditions is close to the experimentally obtained value.     

Medical problems affecting the management of children in dentistry

Medical problems can affect the type and timing of dental treatment in children and also the methods of pain control used. In this paper, conditions which influence the choice of anaesthesia and the performance of nonsurgical and surgical dentistry are discussed, as are conditions which affect dental development.     

石煤钠化焙烧物中不同价态钒的测定

石煤钠化焙烧物中含有V3+、V4+、V5+、Fe2+、Fe3+、SiO2等多种组分。研究了石煤钠化焙烧物中V5+、V4+的碱浸分离,以及V3+、V4+、Fe2+、Fe3+、SiO2在磷酸-氢氟酸介质中的溶解和干扰组分的消除,获得了满意结果。     

Evaluation of Differing Subsurface Ground Conditions in Construction Contracts

Subsurface ground conditions present a big factor of uncertainty in a construction project. It is difficult to determine subsurface ground conditions even with a prebid site investigation. Nevertheless, such conditions must be included in the bid price. Due to this uncertainty, claims arise during the construction of a project. Many claims end up in litigation. This paper presents an analysis of legal cases dealing with differing subsurface ground conditions in construction contracts. By creating a database containing salient features from legal cases related to subsurface ground conditions, this research identifies the most important factors influencing the outcome of legal cases pertaining to subsurface ground conditions. Further, the most commonly used arguments by the litigating parties and the precedent cases supporting them are identified and categorized.     

螺旋离合制动机构在卷扬机上的应用

结合２００ｋｇ手动卷扬机上应用螺旋离合制动机构的实例，对该机构的结构进行了介绍，分析了荷重在提升、吊挂与下降各种状态下的机动原理，提供了满足正常运转必需的验算条件，还对关键零件扭力弹簧的功能与计算条件作了介绍，提出了机构设计中应注意的问题。     

前常铜铁矿采矿方法优化选择

根据前常铜铁矿开采技术条件,运用传统的选择手段,对适用于该条件的采矿方法进行初选,然后应用模糊理论对初选的采矿方法进行了优选,实践证明,模糊理论可以运用于采矿方法的选择,并且将使选择的采矿方法更科学、准确。     

Debonding and Calibration Shift of Optical Fiber Sensors in Concrete

Fiber optic sensors have recently be considered for strain monitoring in concrete structures. The calibration factor of the sensor depends on the strain distribution along the fiber. When an embedded fiber is under strain, debonding may occur, causing the strain distribution and hence the calibration to change. Since interfacial properties that govern debonding are sensitive to environmental conditions, the calibration factor can also change when exposed to various environments. In this paper, a theoretical framework is developed to quantify the effect of environmental conditions on calibration shift. To illustrate the application of the theoretical approach, pullout test results on specimens subjected to various environmental conditions are first analyzed to obtain interfacial parameters. With these parameters, the effects of applied strain, environmental conditions, and fiber length on the calibration factor of two kinds of fiber optic sensors are quantified with the use of a strain transfer model. Based on the results, design guidelines to minimize calibration shift can be identified.     

Cultural-societal roots of violence: The examples of genocidal violence and of contemporary youth violence in the United States.

Widespread violence in a society must have its origins in cultural characteristics, current societal conditions, or both. In this article, the cultural, societal, and psychological origins of two very different forms of violence are examined. A conception of the origins of genocide and mass killing is briefly presented, with the Holocaust and the violence in the former Yugoslavia as supporting evidence. Difficult life conditions give rise to scapegoating, destructive ideologies, and the evolution of increasing violence against a designated enemy. Cultural characteristics that make this process more or less probable are described. This is followed by a presentation of the socialization experiences of children that generate youth violence. To explain the increase in youth violence, the presence of difficult life conditions in the United States is noted (due primarily to substantial social change). The effects of difficult life conditions, cultural characteristics, and social conditions such as poverty and discrimination against minority groups on family life and parenting are described. Similarities and differences in the origins of the two forms of violence are examined.… (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Asymmetric deformation of metal and front flexure of thick sheet in rolling. Part 2

Laboratory experiments are followed by the rolling of sheet in industrial conditions on 3600, 2300, and 5000 thick-sheet mills. The parameters that affect the front curvature of the sheet leaving the rollers are identified. The sheet-reduction conditions on the 3600 and 2300 mills are assessed, so as to determine the rolling parameters responsible for asymmetry of the process in the vertical plane. Means of compensating the sheet flexure at the roller exit are proposed.     

Age differences in lapses of intention in the Stroop task

The study evaluated the hypothesis that older adults are more susceptible to lapses of intention (lapses) than are younger adults, and explored the factors contributing to these lapses. The findings of three experiments examining the pattern of intrusion errors in the Stroop task revealed that older adults were more likely to experience lapses than were younger adults, and that lapses tended to be of longer duration in older than younger adults. Lapses were observed under conditions of suboptimal controlled attentional processing, when task conditions required the allocation of this processing in the service of multiple behavioral goals, and during periods of slowed responding. The findings of these experiments are consistent with those from a growing number of studies indicating that older adults are more susceptible to lapses of intention than younger adults.     

Usefulness of transesophageal echocardiography in predicting mortality and morbidity in stroke patients without clinically known cardiac sources of embolus

Shoulder pain is encountered commonly in older people. Most of the conditions are amenable to nonoperative treatment, but a clear understanding of the anatomy and those conditions encountered most commonly is essential. A careful history and physical examination, as well as limited diagnostic tests, point to a clear diagnosis in the majority of patients. Most often, conservative measures are effective. Steroid injections are often helpful for both diagnostic and therapeutic reasons. A small percentage of patients do not respond to conservative management and require operative intervention.     

Phase compositions of titanium and chromium coatings produced by reactive deposition in an active gas atmosphere

The structures of titanium-and chromium-based coatings produced by electron-plasma deposition in an active gas atmosphere consisting of N₂, CO₂, C₂H₂, and their binary (50: 50) mixtures have been studied. Phase-composition data are used to analyze the conditions of interaction between a deposited metal and the gas atmosphere. These conditions are shown to be much more severe than in gas-saturation processes under furnace conditions. As a consequence, the reactions of active gases on the coating surface go to completion, and the conditions of phase equilibria during coating formation are shifted toward high active-gas pressures at a given deposition temperature.     

Estimating in situ exposure in the presence of acoustic nonlinearity

Evidence is presented for excess attenuation of pulsed ultrasound due to finite amplitude effects in water. Measurements on a modern scanner are used to demonstrate that linear derating can underestimate many exposure quantities, including all safety indices apart from the cranial thermal index. More appropriate methods for estimating in situ exposure are reviewed. A preferred procedure that requires exposure measurements to be made in water under "small signal" conditions is selected. A spectral index is defined that is proposed as an indicator of finite amplitude effects, where spectral index = 0.1 defines the threshold between nonlinear and quasi-linear conditions.