μ Control for Satellites Formation Flying

In this paper, a μ controller is designed for a satellite formation flying system around the Earth based on an uncertainty model derived from a nonlinear relative position equation. In this model, nonzero eccentricity and varying semimajor axis are included as parametric uncertainties. J2 perturbation, atmospheric drag, and actuation and sensor noise are bounded by functional uncertainties. The μ controller design based on the nominal mission (an 800?km altitude circular reference orbit) is capable of achieving desired performance, is robust to uncertainties, and satisfies fuel consumption requirements even in a challenge nonnominal mission (a 0.1 eccentricity and 7,978?km semimajor axis elliptic reference orbit) with the same control gain. In this nonnominal mission, the designed μ controller is able to keep formation with almost the same level of the ΔV budget (43.86?m/s/year) as used in the nominal mission (39.65?m/s/year). For comparison, linear quadratic regulator (LQR) and sliding mode controllers (SMC) are developed and extensively tuned to get the same ΔV consumption as that of the designed μ controller for the nominal mission. However, as shown in the simulation, the designed linear robust controller (LQR) and nonlinear robust controller (SMC) have a serious ΔV consumption penalty (1.72?km/s/year for SMC) or are unstable (for LQR) in the nonnominal mission.     

Introduction to the special section on cognitive processes and psychotherapy.

Theoretical models featuring cognitive processes have played a fundamental role in advancing knowledge of psychopathology and its treatment and have emphasized the importance of cognition in psychotherapy. Recognition of the importance of cognition in psychotherapy has led to a number of questions that are addressed by the articles in this special section of the Journal of Consulting and Clinical Psychology. Cognitive therapy is well represented in the articles in this special section, but therapeutic procedures that do not represent typical cognitive therapy are also examined. The articles in this special section focus on homework in the modification of cognition, cognition in the treatment of anxiety in adults and in children, change in depressive cognitions in children, cognition and rapid change in the treatment of depression, and the role of cognition in the treatment and prevention of depression that is recurrent. Examination of these types of questions holds the possibility of advances in existing treatments and the possibility of innovations in new treatments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

SAR ADC驱动运算放大器的选择

运算放大器输出级极限 运算放大器的轨至轨运行是指其输入级或输出级,或者是指其输入级与输出级.作为驱动SAR ADC输入端的一个缓冲器,我们更关注运算放大器轨至轨的输出能力.     

Design of Managed Aquifer Recharge for Agricultural and Ecological Water Supply Assessed Through Numerical Modeling

The Walla Walla Basin, in Eastern Oregon and Washington, USA, faces challenges in sustaining an agricultural water supply while maintaining sufficient flow in the Walla Walla River for endangered fish populations. Minimum summer river flow of 0.71 m³/s is required, forcing irrigators to substitute groundwater from a declining aquifer for lost surface water diversion. Managed Aquifer Recharge (MAR) was initiated in 2004 attempting to restore groundwater levels and improve agricultural viability. The Integrated Water Flow Model (IWFM) was used to compute surface and shallow groundwater conditions in the basin under water management scenarios with varying water use, MAR, and allowable minimum river flow. A mean increase of 1.5 m of groundwater elevation, or 1.5 % of total aquifer storage, was predicted over the model area when comparing maximum MAR and no MAR scenarios where minimum river flow was increased from current level. When comparing these scenarios a 53 % greater summer flow in springs was predicted with the use of MAR. Results indicate MAR can supplement irrigation supply while stabilizing groundwater levels and increasing summer streamflow. Potential increase in long-term groundwater storage is limited by the high transmissivity of the aquifer material. Increased MAR caused increased groundwater discharge through springs and stream beds, benefiting aquatic habitat rather than building long-term aquifer storage. Judicious siting of recharge basins may be a means of increasing the effectiveness of MAR in the basin.     

Developers, regeneration and sustainability issues in the reuse of vacant industrial buildings

The outcomes from a survey of developer and related organizations active in a local industrial property market in mid-1998 are reported in respect of the use and reuse of industrial buildings. The discussion focuses on both refurbishment and reuse and new build sectors, and draws out some evidence on sustainability issues. Despite a relatively limited understanding of sustainability as a concept, developers are found to have a positive attitude to reuse when conditions allow it. Indeed, those more actively involved in reuse have sometimes engaged in a variety of practical, sustainable solutions to refurbishment needs. Most are open to influence on questions of good practice and sustainability. This all suggests that legislation designed to turn the development and construction industry towards brownfield opportunities and the sustainable reuse of existing infrastructure is likely to induce a favourable response. Cet article presente les resultats, a la mi-1998, d'une etude menee par des promoteurs et des entreprises du secteur actives sur le marche de la propriete industrielle locale sur l'utilisation et la reutilisation des batiments industriels. Le debat porte, pour l'essentiel, sur la remise en etat, la reutilisation et les constructions nouvelles; les conclusions mettent en lumiere des evidences en ce qui concerne les questions de durabilite. Malgre une comprehension relativement limitee du concept de durabilite, il s'avere que les promoteurs ont une attitude positive en ce qui concerne la reutilisation de batiments lorsque les conditions le permettent. Certes, les plus actifs dans le secteur de la reutilisation se sont parfois orientes vers l'option de la remise en etat en proposant une grande variete de solutions pratiques et durables. La plupart d'entre eux restent ouverts aux questions de bonne pratique et de durabilite. Tout cela suggere que la legislation visant a orienter les promoteurs et les entreprises du batiment vers des opportunites d'investissement dans des installations existantes et vers la reutilisation durable d'infrastructures existantes est susceptible d'entrainer une reponse favorable.     

Longitudinal patterns of risk for depression in dementia caregivers: Objective and subjective primary stress as predictors.

The present study examined how patterns of risk for depression over 1 year in 188 dementia caregivers (consistently asymptomatic, n ?=?88; consistently symptomatic, n ?=?40; changing risk, n ?=?60) could be predicted by objective (behavior problems of the relative) and subjective (role captivity and overload) primary stress. Results reveal that all primary stressors differentiated caregivers who remained at low levels of symptomatology over the course of 1 year from those who were at risk for experiencing a depressive disorder. In addition, caregivers' subjective experience of role captivity predicted the chronicity of risk. Findings extend prior caregiving research on patterns of depressive symptomatology by highlighting the relationship between subjective primary stressors and stability and change in caregivers' mental health. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

将电阻式触摸屏用于人／机接口

触摸屏被有效应用于多种信息设备中，如个人教字助理（PDA）以及用于仪表与控制应用领域的通用指示器等。从触摸屏获取信息，井将这些信息传辅至德处理器是一项复杂的难题。本文将介绍电阻式触摸屏的基本工作原理，以及如何高效地将这些模拟辅入信息转换为可用的教字信息，井将解决诸如建立时间、噪声过滤以及速度权衡等问题。