Promoting sustainable sanitation through wastewater-fed aquaculture: a case study from Ghana

Several of the 10 key challenges targeted by the African Water Vision 2025 are directly or indirectly related to human waste management, in particular strengthening the financial base for providing adequate sanitation services. This case study describes a novel approach to improving the operation and maintenance of a waste stabilization pond system in Ghana by turning it into a dual-purpose wastewater treatment plant and commercial fish farm. Results of a collaborative pilot study between private, public and academic partners to test the institutional and technical feasibility of the model as well as the public health impacts are presented.     

关联时滞大系统的时滞相关镇定

针对具有n2个时滞关联大系统的时滞相关镇定问题,本文基于线性矩阵不等式方法,通过构造适当的Lyapunov—Krasovskii泛函,给出了基于此类大系统分散反馈镇定的充分条件及状态反馈控制器的设计方案,并用数值例子进行验证,所得结果是将现有的时滞无关条件推广到时滞相关条件,证明了所得结论的有效性。     

基于欧拉四元数的欠驱动航天器姿态稳定性滑模控制

针对欠驱动航天器姿态稳定的非线性控制设计问题,给出了欠驱动航天器的姿态动力学方程和基于四元数描述的姿态运动学方程。根据航天器欠驱动轴的角速度分量是否为零分别设计相应的姿态稳定控制律。欠驱动轴角速度分量不为零时引进角速度误差和滑模函数,提出基于滑模函数的反馈控制律,使欠驱动航天器姿态达到稳定状态。数值仿真实验结果表明了所设计控制律的有效性。     

非完整移动机器人的鲁棒镇定

本文针对一类典型的不确定非完整运动学系统--两轮驱动的平面移动机器人,研究了其鲁棒镇定问题。首先给出单目摄像机下的移动机器人的视觉模型,然后建立（2.0）型非完整移动机器人的运动学模型,在视觉参数未知的情形下,设计一种能使系统渐近稳定的控制器,并严格证明了闭环系统的稳定性,仿真结果验证了所设计控制器的有效性。     

不确定仿射非线性奇异系统的鲁棒稳定性

为保证一类仿射非线性奇异系统的运行品质,需要对系统的鲁棒性进行控制.描述了系统的不确定性,将非线性系统鲁棒稳定性分析方法推广到此类系统,提出了不确定非线性奇异系统鲁棒稳定性的概念,并给出了分析方法.利用系统的向量相对阶和标准型,分析了系统的鲁棒稳定化问题.论证结果表明,在其系统和不确定性满足某些匹配条件时,可构造反馈控制律,使其闭环系统获得鲁棒稳定性,并能获得系统鲁棒稳定化的反馈控制律设计方法.     

长江下游马鞍山河段河道治理初步研究

 归纳总结了长江马鞍山河段基本情况、近期河道演变特点和河道治理概况;根据现有河势条件及近年崩岸险情,分析指出了目前本河段存在的主要问题;结合河道治理规划情况,探讨了下一步河道治理措施。研究认为：河势调整工程是该河段整治的关键,重点是通过数学模型和河工模型试验研究提出河势调整工程方案;主要是在左岸新河口一带布置导流工程和上下何家洲及心滩串沟封堵并岸工程,并辅以江心洲尾的何家洲尾挖槽工程。鉴于整治工程的紧迫性和时效性,建议相关部门尽快开展相关前期工作,为整治工程早日实施创造条件,进而实现该河段河势的稳定。     

Design of robust electric power system stabilizers using Kharitonov’s theorem

A robust power system stabilizer (PSS) is proposed as an effective way to damp-out oscillations in electric power systems. Oscillations of small magnitude and low frequency, linked with the electromechanical models in power systems, often persist for long periods of time and in some cases present limitations on the power transfer capability. The proposed PSS is designed according to Kharitonov’s extremal gain margin theory. It has the following advantages: (i) it is based on simultaneous stabilization of limited number of extreme plants, (ii) the control design can be based on frequency response analysis techniques (root locus diagrams or Nyquist plots) and (iii) the resulting controller is a low-order phase-lead compensator, which is robust to the change of operating points. The proposed power system stabilizer is tested through simulation experiments.     

高压摆喷灌浆技术在水库除险加固工程中的应用

通过对水库除险加固工程中高压摆喷灌浆防渗墙工程设计及施工技术成功经验的总结,论述了高压摆喷灌浆防渗技术的主要施工工艺、技术要点、质量控制以及施工过程中应对特殊情况的处理措施。通过在宝鸡市白家窑水库除险加固工程中的实践应用表明,该技术具有防渗处理效果较好、要求施工平台宽度较小、造价适中等优越性。     

砂土地基混凝土衬砌成渠问题的探讨

鉴于砂土工程性质特殊,给穿越砂土地基的渠道设计、施工和运行期维护带来了许多问题.对砂土特性和砂土地基成渠问题探讨,可为设计方案优化和渠道运行维护提供参考依据.     

Input-to-state stability of impulsive and switching hybrid systems with time-delay

This paper investigates input-to-state stability (ISS) and integral input-to-state stability (iISS) of impulsive and switching hybrid systems with time-delay, using the method of multiple Lyapunov–Krasovskii functionals. It is shown that, even if all the subsystems governing the continuous dynamics, in the absence of impulses, are not ISS/iISS, impulses can successfully stabilize the system in the ISS/iISS sense, provided that there are no overly long intervals between impulses, i.e., the impulsive and switching signal satisfies a dwell-time upper bound condition. Moreover, these impulsive ISS/iISS stabilization results can be applied to systems with arbitrarily large time-delays. Conversely, in the case when all the subsystems governing the continuous dynamics are ISS/iISS in the absence of impulses, the ISS/iISS properties can be retained if the impulses and switching do not occur too frequently, i.e., the impulsive and switching signal satisfies a dwell-time lower bound condition. Several illustrative examples are presented, with their numerical simulations, to demonstrate the main results.