岩爆的相似材料物理模拟研究

 根据不同配合比相似材料的物理力学性质测试结果,选取最具岩爆倾向的相似材料,结合一水电站引水隧洞典型断面,制作大尺寸模型,采取后开孔的隧洞成洞方式进行岩爆物理模拟试验研究。结果表明：在模型的边界条件保持工程区天然应力状态下,隧洞开挖过程中拱顶、拱肩和边墙部位在不同的时间段内分别有较明显的应力、应变突变现象,围岩声发射次数也表现出剧烈增大现象,说明围岩出现明显的岩爆表征。模型在超载条件下出现围岩剥落、鼓折和开裂现象,表明原型隧道段以剥落、鼓折式张性岩爆为主。     

盾构隧道致地层沉降的物理模型试验研究

通过不同隧道埋深、支护压力和掘进速度的盾构隧道施工地表沉降的大型物理模型试验,总结不同条件下的地表沉降规律,分析土压力的变化特性,归纳不同条件下的地表沉降曲线;探讨隧道埋深、支护压力和掘进速度对地表沉降值的影响,推导地表横断面沉降槽计算的经验公式.结果表明:随着隧道埋深增加,地表沉降值减小,地表横向沉降槽影响范围加宽;...     

通过开停控制降低三系统冰箱能耗分析

分析了三系统的三门冰箱开停机的能耗损失原因和数值。通过开停机判断的优化,使原来各个间室的单独开停机组合在一起,减少了开停次数,也即减少了因为开停机造成的能耗损失,实现了节能。     

Pseudotransient Continuation-Based Steady State Solver: Extension to Zero Flow Rates

This paper presents and discusses an extension of the pseudotransient continuation-based steady state solver for hydraulic networks proposed previously to the case of zero flow rates. The original solver, which reduces the solution of the governing nonlinear algebraic equations to the numerical integration of an initial-value problem, has problems in situations in which the head derivative of the flow rate tends to infinity, as is the case with zero flow rates. The extension is on the basis of the use of a model headloss-flow relationship that coincides with the true one at zero and has a finite head derivative at that point. This modified steady state solver is free from some convergence problems that occur in Newton-Raphson method-based solvers when analyzing a pipe network with control devices. The paper includes the results of the numerical analysis of test networks, which demonstrate the convergence of the modified steady state solver for cases in which existing steady state solvers have troubles.     

Calibrating the Water-Hammer Response of a Field Pipe Network by Using a Mechanical Damping Model

Hydraulic transient field tests have been conducted in a water distribution network. Existing transient models are applied to model the measured responses, but poor matches are obtained apart from the estimation of the initial rise of pressure. Possible reasons for these discrepancies include the effects of demands, entrained air, unsteady friction, friction losses associated with small lateral pipes, and mechanical damping caused by the interaction of pipes and joints with surrounding soils (including the effects of vibration and different degrees of restraint). These effects are systematically investigated by inclusion of the previously mentioned phenomena in conceptual transient models and calibration to the measured field responses. A mechanical damping-based conceptual transient model is shown to be the only model that can be accurately calibrated to the measured field responses.     

Q235B钢浇铸过程保护渣成分及性能研究

针对涟源钢铁集团有限公司Q235B钢板坯连铸过程中发生的粘结漏钢现象,调查了Q235B钢浇铸过程中保护渣的使用情况,并分析和测定了现场保护渣原始渣样、渣条样和漏钢渣样的主要化学成分和物理性能。研究表明,保护渣浇铸前后Al2O3质量分数变化最大为2．7％;浇铸后熔化温度、熔化速度和黏度分别增加15℃、6s和0．04Pa·s,浇铸前后保护渣物理性能变化不大。     

Prescribing and primary care psychology: Complementary paths for professional psychology.

Two paths have been suggested for the future evolution of professional psychology. Prescribing psychology has already been legally authorized in two states, the military, and the Indian Health Service. Primary care psychology does not require legal recognition and has been slowly growing as a career option for psychologists across the nation. Both paths have their obstacles and limitations, but both are also associated with great potential. This article provides a brief summary of the strengths and weaknesses of each path and suggests an integrated perspective for planning the future of the profession. Each is seen as complementary to the other and providing a basis for pursuing the other. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Distributed-Controlled Multiagent Mobile Platform with Digital Actuation Concept for Space Applications

This paper describes an architecture for a multiagent robotic system that consists of a number of identical units. The homogeneous units are mechanically connected to construct a mobile platform named a “multiagent transportation (MAT) system.” Every unit has its local controller that communicates only with its adjacent units. This basic configuration of supervisorless structure affirmatively confines the dependence of each unit to a local area, and therefore any unit can be removed from or added into any part of a MAT system regardless of the timing and without disturbing the performance of the whole system. This flexibility of configuration significantly contributes to easy maintenance of units, such as battery charging or hot-replacing for faulty units. Utilizing this flexibility, MAT systems are able to adapt to a variety of tasks including transportation application and to target objects of various shapes and range of mass. These characteristics of MAT systems are the strong advantages for mobile robots, especially for ones activated in distant places, e.g., robotic planetary explorers. A proposed example unit of a MAT system shown in this paper employs a parallel link manipulator as its leg, and the digital-actuation (D-actuation) concept is applied for the local unit controller to actuate the leg. Together with the basic design of the example units, the controlling framework is described with simulation results to show the feasibility of the whole mobile system architecture.     

Childhood physical abuse, internalized homophobia, and experiential avoidance among lesbians and gay men.

This study explored relations among childhood physical abuse, internalized homophobia, experiential avoidance, and current psychological symptoms in a community sample of 122 adult lesbians and 115 adult gay men. Childhood physical abuse predicted depression and posttraumatic stress disorder (PTSD) symptoms. Furthermore, for gay men, internalized homophobia completely mediated the relation between childhood physical abuse and depression symptoms and partially mediated the relation between childhood physical abuse and PTSD symptoms. However, experiential avoidance did not mediate these relations. In contrast, experiential avoidance partially mediated the relation between childhood physical abuse and PTSD symptoms among lesbians; however, internalized homophobia did not mediate these relations. These findings suggest that internalized homophobia and experiential avoidance may have differential mediating roles in predicting psychological symptoms among lesbians and gay men who have experienced childhood physical abuse. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The long-term efficacy of two computer-tailored physical activity interventions for older adults: Main effects and mediators.

Objective: Low-cost (e.g., computer-tailored) interventions with sustained effects are needed to increase and maintain physical activity in older adults. This study examined the long-term efficacy of 2 computer-tailored physical activity interventions for older adults and its psychosocial and environmental mediators. Methods: A clustered randomized controlled trial (N = 1,971) was conducted that included 3 research arms: (a) basic computer-tailored print intervention, targeting psychosocial mediators; (b) environmentally computer-tailored print intervention, targeting psychosocial and environmental mediators; and (c) no-intervention control group. Interventions were developed using the intervention mapping approach and consisted of 3 computer-tailored letters delivered over 4 months. Questionnaires assessed the study outcomes (i.e., total weekly days and total weekly minutes of physical activity) at baseline and 12 months. Potential mediators (i.e., awareness, attitude, self-efficacy, intention, social influence, intrinsic motivation, self-regulation, and perceived environment) were assessed at baseline and at 3 or 6 months. Results: Multilevel regression analyses revealed that both interventions significantly changed total weekly days of physical activity compared with the control group, but only the environmentally computer-tailored print intervention significantly changed weekly minutes of physical activity. Multiple mediation models showed that the effects of both interventions on weekly days of physical activity were mediated by changes in awareness and intention. Conclusions: Computer-tailored interventions were effective in inducing long-term behavioral changes in physical activity behavior of older adults. Awareness and intention were found to be important mediators of changing daily physical activity and should be included in future computer-tailored intervention studies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)