A High Order Bound Preserving Finite Difference Linear Scheme for Incompressible Flows

We propose a high order finite difference linear scheme combined with a high order bound preserving maximum-principle-preserving (MPP) flux limiter to solve the incompressible flow system. For such problem with highly oscillatory structure but not strong shocks, our approach seems to be less dissipative and much less costly than a WENO type scheme, and has high resolution due to a Hermite reconstruction. Spurious numerical oscillations can be controlled by the weak MPP flux limiter. Numerical tests are performed for the Vlasov-Poisson system, the 2D guiding-center model and the incompressible Euler system. The comparison between the linear and WENO type schemes, with and without the MPP flux limiter, will demonstrate the good performance of our proposed approach.     

针刺辅助治疗难治性肠易激综合征临床试验方案关键点设计的思考＊

肠易激综合征（Irritable bowel syndrome，IBS）是临床常见病、多发病，其治疗方法丰富，但部分患者疗效欠佳，发展成难治性IBS。目前国内外关于针灸治疗难治性IBS的临床随机对照试验尚不多见。本文立足试验方案设计的“PICOS”原则，从研究对象及诊断标准、干预措施、对照措施、结局指标四个方面入手，重点探讨针刺辅助治疗难治性肠易激综合征临床试验设计的关键要点。从选择特色优势病种、明确诊断标准、制定符合临床实际的干预方案、运用符合目标的安慰针刺、结合研究设计和目的选定结局指标几个角度，阐述试验相关环节设计的原因和思考。     

Discrete time optimal control of linear time-delay systems

A discrete time optimal control for linear time-delay systems is developed to ensure that all closed-loop eigenvalues will lie inside a circular region centred at (β;, 0) with radius α. It is shown that by suitable manipulations the problem can be reduced to a standard discrete time quadratic regulator problem. An illustrative example is included to demonstrate the applicability of the proposed method.     

根除幽门螺杆菌5种治疗方案的药物经济学评价

目的 探讨不同的方案根除幽门螺杆菌(Hp)所产生的经济效果。方法 151例幽门螺杆菌阳性感染的消化性渍疡和胃炎患者，随机分为5组，给予不同的短程三联治疗方案：A组(胶体次枸橼酸铋 阿莫西林 甲硝唑)、B组(胶体次枸橼酸铋 克拉霉素 甲硝唑)、C组(奥美拉唑 阿莫西林 克拉霉素)、D组(奥关拉唑 阿莫西林 甲硝唑)、E组(奥美拉唑 克拉霉素 甲硝唑)，运用药物经济学的成本-效果分析方法进行评价。结果A、B、C、D、E5组治疗胃炎Hp根除率分别为63．2％、70．9％、89．1％、77．6％、86．8％，治疗消化性溃疡Hp根除率分别为65．1％、73．0％、96．2％、80．4％、93．2％，5组方案对胃炎／消化性溃疡的成本-效果比(C／E)分别为3．14／3.05、4．10／3．98、4．25／3．94、2．91／2.81、2．78／2．59，增长的成本-效果比(△C／△E)分别为-／-、12．00／11．70、6．96／5．80、1．93／1．81、1．83／1．53。结论 E方案为根除Hp的最佳方案。     

Optimal response in siso ripple-free deadbeat systems

The ripple-free deadbeat control problem for SISO plants subjected to arbitrary reference signals is considered. The trade-off between the settling time and the integral square error between the system output and reference signal is investigated. Given a specific order of the controller, it is shown how to design an optimal ripple-free deadbeat controller. An illustrative example is presented to show the feasibility of the proposed algorithm.     

An optimal dynamic output feedback controller for a flexible spacecraft

The design of a low-order dynamic output feedback controller for a flexible spacecraft is carried out using modified linear quadratic Gaussian (LQG) theory. The necessary conditions for optimization are given. The linear equations governing a flexible spacecraft with a central rigid body and two sun-tracking solar panels are presented. The parameters of the Solar Electric Propulsion Spacecraft (SEPS) are selected for analysis and simulation. The optimal gains for the dynamic controller are estimated using an iterative algorithm. The sequential procedure which assures convergence is selected. The initial gains which stabilize the system are chosen on the basis of the principle of a PD controller. A third-order controller for pitch, roll and yaw axes of the 18th-order system, which includes sensor and actuator dynamics, is designed. Numerical simulations carried out to ascertain the performance of the controller show the performance to be satisfactory.     

A multi-input/multi-output optimal PI controller for redundant robots in the presence of flexible disturbances

The two-stage synthesis of a multi-input/multi-output optimal proportional-integral (PI) controller is described for linear, time-invariant systems. In the first stage the PI controller is designed by solving a steady state algebraic Riccati equation. As a result, the optimal cost is expressed in terms of the system's constant output set-points. In the second stage the cost is further reduced by optimally selecting the output set-points to minimize a static quadratic performance index subject to linear algebraic constraints. The design framework is applied to a planar redundant robotic manipulator equipped with four joints and mounted at the tip of a long flexible arm. We then address the problem of self-motion control in the presence of vibratory disturbances.     

The Heartbeat Award Scheme: an evaluation of catering practices

The Heartbeat Award Scheme was launched in England in 1990 by the Health Education Authority as part of the national strategy to reduce the incidence of coronary heart disease. To date there has been no formal evaluation of the impact the award has had on catering practices. This study aimed to compare the differences between those premises with and without the award with regard to their catering practices. All Heartbeat premises (497) within the former Wessex region, along with 495 control premises without the award, were sent postal questionnaires. A total of 380 premises with the award and 306 premises without responded, representing a response rate of 77% and 62%, respectively. Respondents were grouped into one of three categories: public eating places, workplaces or educational establishments. Differences were found between award and non-award holders, particularly with regard to the provision of healthy food, including brown rice and semi/skimmed milk, healthy options available to the consumer and commitment to healthy eating. While this research suggests that the award scheme may be increasing consumer choice, it is not possible to draw conclusions about the impact of the scheme on eating habits.     

关于新型农村合作医疗的支持结构及均势模式探讨

新型农村合作医疗可持续发展需要有完备的社会支持系统,除了要有来自政府的正式支持,如政府责任、完善的组织管理及合理的政策方案外,其他非正式支持同样对新型农村合作医疗的发展有着至关重要的影响。通过研究新型农村合作医疗的社会支持系统结构,探讨社会因素对新型农村合作医疗的双向作用,提出新型农村合作医疗发展的社会支持模式,为提高新型农村合作医疗社会支持程度提供科学依据。