Robust reliable H_∞ control for a class of uncertain time-delay systems

This paper deals with the problem of robust reliable H∞ control for a class of uncertain nonlinear systems with time-varying delays and actuator failures. The uncertainties in the system are norm-bounded and time-varying. Based on Lyapunov methods, a sufficient condition on quadratic stabilization independent of delay is obtained. With the help of LMIs (linear matrix inequalities) approaches, a linear state feedback controller is designed to quadratically stabilize the given systems with a H∞ performance constraint of disturbance attenuation for all admissible uncertainties and all actuator failures occurred within the prespecified subset. A numerical example is given to demonstrate the effect of the proposed design approach.     

A causation mechanism for coal bursts during roadway development based on the major horizontal stress in coal: Very specific structural geology causing a localised loss of effective coal confinement and Newton's second law

In 2017, one of the international authorities on coal bursts, Mark Christopher, published a paper entitled‘‘Coal bursts that occur during development: A rock mechanics enigma", in which several relevant technical issues were identified. This paper outlines what is considered to be a credible, first-principles,mechanistic explanation for these three current development coal burst conundrums by reference to early published coal testing work examining the significance of a lack of ‘‘constraint" to coal stability and an understanding of how very specific structural geology and other geological features can logically cause this to occur in situ, albeit on a statistically very rare basis. This basic model is examined by reference to published information pertaining to the development coal-burst that occurred at the Austar Coal Mine in New South Wales, Australia, in 2014 and from the Sunnyside District in Utah, the United States.The ‘‘cause and effect" model for development of coal bursts presented also offers a meaningful explanation for the statistical improbability for what are nonetheless potentially highly-destructive events, being able to explain the statistical rarity being just as important to the credibility of the model as explaining the local conditions associated with burst events. The model could also form the basis for a robust, riskbased approach utilising a ‘‘hierarchy of controls", to the operational management of the development coal burst threat. Specifically, the use of pre-mining predictions for likely burst-prone and non-burstprone areas, the use of the mine layout to avoid or at least minimise mining within burst-prone areas if appropriate, and finally the development of an operational Trigger Action Response Plan(TARP) that reduces the likelihood of inadvertent roadway development into a burst-prone area without suitable safety controls already being in place.     

低凸起带油气充注机理及运聚模式:以济阳坳陷林樊家低凸起带为例

断陷盆地低凸起带具有远离油源,油气富集层系浅的特点,其油气充注机理及运聚模式研究还较薄弱。以济阳坳陷林樊家低凸起带为例,从油气来源入手,分析了油气成藏动力与阻力的关系,探讨了低凸起带油气充注方式和运聚模式。结果表明:林樊家低凸起带原油具有高伽马蜡烷/C30霍烷值、低姥植比的特点,来源于利津洼陷沙四上亚段烃源;在成藏地质背景分析的基础上,结合成藏动力-阻力计算结果,确定了林樊家低凸起带油气主要为“断层双重输导-多层系充注-不整合面分流”的充注方式;根据断层在活动时期和静止时期输导方式及输导能力的差异,结合圈闭发育情况,林樊家低凸起带油气成藏可总结为“断层垂向输导-岩性尖灭控圈”。“断层侧向输导-‘天窗’开启-岩性尖灭控圈”、“断层侧向输导-不整合面遮挡”、“断层侧向输导-岩性尖灭控圈”等4种成藏模式。     

电液比例系统鲁棒自适应动态表面控制

对基于语义网络的产品建模及配置方案的搜索方法进行集成研究,以提高产品配置设计的效率.在相关本体的基础上,建立了基于语义网络的产品模型结构,并据此解析用户所输入的查询语句.基于语义网络的产品模型提供一种定量与定性相结合的一致化的设计实例与需求的表达方式.进一步通过产品的语义网络模型可以获取设计需求的隐含条件,使得需求在设计方案的搜索匹配过程中被更充分地考虑.配置设计方案的搜索则首先利用基于语义网络的推理技术与本体语言RDFS构造待求配置设计问题的语义网络片断,然后通过语义搜索与匹配度计算排序从设计实例库中获取符合当前需求配置设计方案.同时,通过注塑机螺杆为实例的应用证明了基于语义网络的产品模型在支持配置选型设计方案搜索方面的有效性与实用性.相对于传统的产品模型而言,基于语义网络的产品模型更关注属性之间的内部联系,经实例验证基于语义网络的产品模型使得配置设计过程更符合用户的实际需求.     

Robust interference alignment for norm-bounded channel uncertainties

Conventional interference alignment (IA) requires perfect channel state infromation and is sensitive to channel uncertainties. Based on the norm-bounded channel uncertainties model, this paper proposes three worst-case approach robust IA algorithms. First, to decrease the interference and signal leakage, a robust algorithm is proposed to minimize the maximum leakage power; Second, to increase the interference and signal in the corresponding subspace, another robust algorithm is proposed to maximize the minimun subspace projection; finally, a united robust algorithm is proposed by uniting the two algorithms above. Simulation results show that the proposed algorithms can outperform the conventional algorithms when channel uncertainties are norm-bounded, which affirms the robustness of the proposed algorithm.     

大牛地气田钻井液不落地技术与实践

大牛地气田地表环境差、钻井废弃物多。为加强环境保护和提高钻井废弃物的再利用效率,实现气田绿色经济开发,从硬件装备和钻井液体系方面,逐步试验了以"砖砌泥浆池+成熟钻井液体系"、"撬装式设备+环保钻井液"为主体的钻井液不落地技术。现场应用21口井,实践表明:撬装式设备与环保钻井液一体化的钻井液不落地技术环保、节能减排效果良好。该技术规模化应用能提高废弃物的回用价值,提高油田经济效益和环保效益。     

不确定网络化控制系统保性能控制器设计

针对一类具有时变网络诱导时延的不确定网络控制系统,研究了一种可以对时变时延进行补偿的保性能控制器的设计问题。通过引入两个附加的松弛矩阵使Lyapunov矩阵和系统矩阵分离,得到了一个新的时延补偿保性能判据,并基于该判据设计了系统的保性能状态反馈控制器。当将其应用于具有凸多面体不确定性的网络控制系统时,可以得到与系统不确定性相关联的Lyapunov函数,有效降低了设计的保守性,并且设计了一个迭代算法来得到问题的优化解。最后通过一个算例验证了所提出的时延补偿策略的可行性和优越性。     

A robust multi-objective and multi-physics optimization of multi-physics behavior of microstructure

A new strategy is presented to solve robust multi-physics multi-objective optimization problem known as improved multi-objective collaborative optimization(IMOCO) and its extension improved multi-objective robust collaborative(IMORCO).In this work,the proposed IMORCO approach combined the IMOCO method,the worst possible point(WPP) constraint cuts and the Genetic algorithm NSGA-II type as an optimizer in order to solve the robust optimization problem of multi-physics of microstructures with uncertainties.The optimization problem is hierarchically decomposed into two levels: a microstructure level,and a disciplines levels.For validation purposes,two examples were selected: a numerical example,and an engineering example of capacitive micro machined ultrasonic transducers(CMUT) type.The obtained results are compared with those obtained from robust non-distributed and distributed optimization approach,non-distributed multi-objective robust optimization(NDMORO) and multi-objective collaborative robust optimization(McRO),respectively.Results obtained from the application of the IMOCO approach to an optimization problem of a CMUT cell have reduced the CPU time by 44% ensuring a Pareto front close to the reference non-distributed multi-objective optimization(NDMO) approach(mahalanobis distance,D_M~2=0.9503 and overall spread,S_o=0.2309).In addition,the consideration of robustness in IMORCO approach applied to a CMUT cell of optimization problem under interval uncertainty has reduced the CPU time by 23% keeping a robust Pareto front overlaps with that obtained by the robust NDMORO approach(D_M~2=10.3869 and S_o=0.0537).     

油藏地质建模及实时跟踪研究

为了提高采收率,降低开发风险,以滩海地区某油田为研究对象,结合地质、测井、地震等资料,对该油藏进行实时跟踪地质特征综合研究。应用地质建模、随钻测井、地质导向等技术,建立了精细的三维地质导向模型,并根据随钻测井数据和综合地质信息,实时验证构造和储集层信息,对导向模型不断校正,使模型与实钻结果一致,还以该模型为基础,优化水平井钻井的前进轨迹。结果表明,此种方法的应用降低了海上油田开发风险,能取得良好的开发效果。     

不确定线性系统的容错控制器设计

针对一类含有时变范数有界参数不确定性和部分执行器可能失效的系统,结合一个二次型性能指标,研究了使得闭环系统保持稳定,且闭环性能指标值不超过某个确定界的鲁棒容错状态反馈控制率的设计问题,通过求解一个代数Riccati方程的对称正定解给出了鲁棒容错控制率的构造。     

综合超前地质预报在岩溶隧道施工中的应用

在岩溶地区,富水、岩溶及断层破碎带等不良地质常是制约隧道正常施工的主要因素。超前地质预报是探查地下工程开挖掌子面前方不良地质情况、降低施工风险的一项重要技术措施,已成为岩溶地区隧道施工过程中不可或缺的重要工序。文章提出了运用“地质调查法+TSP+TEM+超前钻探”综合地质预报方法对岩溶地区隧道不良地质情况进行探查,建立了在地质调查法的基础上,使用TSP长距离辅助探测技术,以小线圈瞬变电磁法为核心手段,最后再通过超前地质钻孔来验证的综合预报流程。以某岩溶地区隧道为工程背景,采用了“地质调查法+TSP+TEM+超前钻探”综合超前预报方法,达到了提高预报准确性的效果。     

Adaptive fuzzy integral sliding mode pressure control for cutter feeding system of trench cutter

A nonlinear pressure controller was presented to track desired feeding pressure for the cutter feeding system (CFS) of trench cutter (TC) in the presence of unknown external disturbances. The feeding pressure control of CFS is subjected to unknown load characteristics of rock or soil; in addition, the geological condition is time-varying. Due to the complex load characteristics of rock or soil, the feeding velocity of TC is related to geological conditions. What is worse, its dynamic model is subjected to uncertainties and its function is unknown. To deal with the particular characteristics of CFS, a novel adaptive fuzzy integral sliding mode control (AFISMC) was designed for feeding pressure control of CFS, which combines the robust characteristics of an integral sliding mode controller and the adaptive adjusting characteristics of an adaptive fuzzy controller. The AFISMC feeding pressure controller is synthesized using the backstepping technique. The stability of the overall closed-loop system consisting of the adaptive fuzzy inference system, integral sliding mode controller and the cutter feeding system is proved using Lyapunov theory. Experiments are conducted on a TC test bench with the AFISMC under different operating conditions. The experimental results demonstrate that the proposed AFISMC feeding pressure controller for CFS gives a superior and robust pressure tracking performance with maximum pressure tracking error within ±0.3 MPa.

     

Robust Topology Optimization of Vehicle Suspension Control Arm

A robust topology optimization design framework is developed to solve lightweight structural design problems under uncertain conditions. To enhance the calculation accuracy and flexibility of the statistical moments of robust analysis, number theory integral method is applied to sample point selection and weight assignment. Both the structure topology optimization and number theory integral methods are combined to form a new robust topology optimization method. A suspension control arm problem is provided as a demonstration of robust topology optimization methods under loading uncertainties. Based on the results of deterministic and robust topology optimization, it is demonstrated that the proposed robust topology optimization method can produce a more robust design than that obtained by deterministic topology optimization. It is also found that this new approach is easy to apply in the existing commercial topology optimization software and thus feasible in practical engineering problems.     

基于小波神经网络的变参数振动钻削仿真

为了改变因寻找最优振动参数和切削参数而需要在实验中大幅度频繁地改变参数的状况,利用小波函数对一维信号逼近能力较强的特点,提出了一种适用于变参数振动钻削加工过程仿真的小波神经网络模型, 并运用灰色理论中的关联分析法对小波神经网络输入权值进行选取。理论分析和实验表明:应用该仿真模型,能在振动钻削过程的不同区段寻找最优的振动参数和切削参数。     

Die Sterbehilfedebatte und das Bild der Palliativmedizin in deutschen Printmedien

Background In Germany the discussion about euthanasia and physician assisted suicide is prevalent in the media. This study will analyse the way German newspapers represent the discussion about the end of life and how they report about palliative medicine. Methods A qualitative data analysis was performed of 433 articles published in the years 2006 and 2007 in different German newspapers. The archives of the selected newspapers were searched for “palliative medicine”, “hospice”, “patient’s autonomy”, “patient’s will”, “euthanasia” and “terminal care”. Results Dignity, autonomy, inadequate provision of care and uncertainties were identified as the major topics in the debate about euthanasia. Dignity was used both as an argument for and against legislation of euthanasia. The terminology on euthanasia is not used consistently in Germany. Palliative medicine is described as a possible alternative to euthanasia which should be developed and reimbursed better. Conclusion These findings underline the importance of dignity and autonomy for the public opinion on the end of life. The media show the potential of palliative medicine as an alternative to euthanasia but claim further development of palliative care. The inconsistencies in terminology as well as in the content of end of life decisions have to be clarified to allow an objective discussion. Politicians and the medical profession should know about the public statements and opinions, to react adequately to patient’s fears and allowances.     

2-D奇异系统的鲁棒稳定性分析

考虑具有结构不确定性的2-D奇异系统Roesser模型(简称2-DSRM)鲁棒稳定性问题，提出了一种新的鲁棒稳定性分析方法，得到了2-D奇异系统在结构摄动下仍保持容许、稳定、无跳跃模的充分条件。     

含未建模动态的非线性参数系统的鲁棒自适应控制

许多实际系统如生化过程、带有摩擦的机器等都是具有不确定性的非线性参数系统。如何有效地控制这类系统是-富有挑战性问题。针对一类重要的非线性参数系统提出了一种鲁棒自适应控制器，可用于存在参数和非线性不确定性、未知扰动和未建模动态的情况。该鲁棒自适应控制器的设计是基于控制李亚普诺夫函数法，通过引入一动态信号和自适应非线性阻尼来抑止未建模动态、非线性不确定性和未知有界扰动的影响，同时采用反推设计方法来克服控制器设计的复杂性。所提方法不必对系统的未知参数进行估计，且无论系统的阶次多高、未知参数多少，只需要一个自适应参数。理论证明，所提出的鲁棒自适应控制器可保证整个具有不确定性的非线性参数系统的稳定性，且通过适当选择设计参数，可使状态以任意精度趋于平衡点。仿真结果例证了所提方法的有效性。     

Design of robust stability augmentation system for an airship using genetic algorithm

This paper presents the design of stability augmentation system (SAS) for the airship, which is robust with respect to parametric plant uncertainties. A robust pole placement approach is adopted in the design,which uses genetic algorithm (GA) as the optimization tool to derive the most robust solution of the state-feedback gain matrix K. The method can guarantee the resulting closed-loop poles to remain in a specified allocation region despite plant parameter uncertainty. Thus, the longitudinal stability of the airship is augmented by robustly assigning the closed-loop poles in a prescribed region of the left half s-plane.     

均值-方差组合模型的鲁棒投资优化

针对投资组合优化模型中收益率的期望值、协方差矩阵等参数扰动时对原问题最优解产生较大影响的问题,文中提出将鲁棒优化应用到均值-方差投资组合模型中,建立了"势"不确定集下的鲁棒投资组合选择模型,通过市场数据对该模型进行了实证研究.试验结果表明该模型得到的解兼具鲁棒性与最优性.     

参数不确定δ算子系统的鲁棒保成本l_2-l_∞滤波

研究参数不确定δ算子系统鲁棒保成本l2-l∞滤波问题。针对l2-l∞性能这一类扰动抑制度指标,设计滤波器,使滤波误差动态系统是鲁棒渐近稳定的(当外部扰动恒为零时),l2-l∞性能指标上界尽可能的小,同时保证保成本函数具有一定的上界。采用线性矩阵不等式方法,给出了鲁棒保成本l2-l∞滤波器存在的充分条件,进而提出滤波器的设计方法。数值算例验证了该方法的可行性。