Combined indirect and direct method for adaptive fuzzy output feedback control of nonlinear system

A novel control method for a general class of nonlinear systems using fuzzy logic systems （FLSs） is presertted. Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a high-gain observer is used to estimate the derivatives of the system output. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, it is shown that if the approximation accuracy of the fuzzy logic system is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussion.

NEW HYBRID CONJUGATE GRADIENT METHOD AS A CONVEX COMBINATION OF LS AND FR METHODS

In this paper, we present a new hybrid conjugate gradient algorithm for unconstrained optimization. This method is a convex combination of Liu-Storey conjugate gradient method and Fletcher-Reeves conjugate gradient method. We also prove that the search direction of any hybrid conjugate gradient method, which is a convex combination of two conjugate gradient methods, satisfies the famous D-L conjugacy condition and in the same time accords with the Newton direction with the suitable condition. Furthermore, this property doesn't depend on any line search. Next, we also prove that, moduling the value of the parameter t,the Newton direction condition is equivalent to Dai-Liao conjugacy condition.The strong Wolfe line search conditions are used.The global convergence of this new method is proved.Numerical comparisons show that the present hybrid conjugate gradient algorithm is the efficient one.

A Hybrid Decoupled Power Flow Method for Balanced Power Distribution Systems

This paper proposes a hybrid decoupled power flow method for balanced power distribution systems with distributed generation sources. The method formulates the power flow equations in active power and reactive power decoupled form with polar coordinates. Second-order terms are included in the active power mismatch iteration, and constant Jacobian and Hessian matrices are used. A hybrid direct and indirect solution technique is used to achieve efficiency and robustness of the algorithm. Active power correction is solved by means of a sparse lower triangular and upper triangular （LU） decomposition algorithm with partial pivoting, and the reactive power correction is solved by means of restarted generalized minimal residual algorithm with an incomplete LU pre-conditioner. Typical distribution generation models and distribution load models are included. The impact of zero-impedance branches is explicitly modeled through reconfiguring of the adjacent branches with impedances. Numerical examples on a sample distribution system with widespread photovoltaic installations are given to demonstrate the effectiveness of the proposed method.

An Improved Hybrid Method for Inverse Obstacle Scattering Problems

An improved hybrid method is introduced in this paper as a numerical method to reconstruct the scatterer by far-field pattern for just one incident direction with unknown physical properties of the scatterer. The improved hybrid method inherits the idea of the hybrid method by Kress and Serranho which is a combination of Newton and decomposition method, and it improves the hybrid method by introducing a general boundary condition. The numerical experiments show the feasibility of this method.

Optimization of multi-revolution low-thrust transfer based on modified direct method

A modified direct optimization method is proposed to solve the optimal multi-revolution transfer with low-thrust between Earth-orbits.First,through parameterizing the control steering angles by costate variables,the search space of free parameters has been decreased.Then,in order to obtain the global optimal solution effectively and robustly,the simulated annealing and penalty function strategies were used to handle the constraints,and a GA/SQP hybrid optimization algorithm was utilized to solve the parameter optimization problem,in which,a feasible suboptimal solution obtained by GA was submitted as an initial parameter set to SQP for refinement.Comparing to the classical direct method,this novel method has fewer free parameters,needs not initial guesses,and has higher computation precision.An optimal-fuel transfer problem from LEO to GEO was taken as an example to validate the proposed approach.The results of simulation indicate that our approach is available to solve the problem of optimal multi-revolution transfer between Earth-orbits.

Near-zone Direct and Indirect Topographic Effects Based on the Rectangular Prism and Surface Element

Helmert’s second method of condensation is an effective method for terrain reduction in the geoid and quasi-geoid determinations. Condensing the masses outside the geoid to a surface layer on the geoid produces several forms of topographic effects: direct effect on gravity, secondary indirect effect on gravity and indirect effects on the (quasi-) geoid, respectively. To strike a balance between computation accuracy and numerical efficiency, the global integration region of topographic effects is usually divided into near zone and far zone. We focus on the computation of near-zone topographic effects, which are functions of actual topographic masses and condensed masses. Since there have already been mature formulas for gravitational attraction and potential of actual topographic masses using rectangular prism model, we put forward surface element model for condensed masses. Afterwards, the formulas for near-zone direct and indirect effects are obtained easily by combining the rectangular prism model and surface element model. To overcome the planar approximation errors involved with the new formulas for near-zone topographic effects, the Earth’s curvature can be taken into account. It is recommended to apply the formulas based on the rectangular prism and surface element considering the Earth’s curvature to calculate near-zone topographic effects for high-accuracy demand to determine geoid and quasi-geoid.

火山灰质材料的火山灰活性检测方法综述

本文将火山灰质材料的火山灰活性检测方法分为直接法和间接法两大类。其中,直接法包括石灰吸收值法,火山灰反应程度评定法和酸、碱溶出度法;而间接法包括物理性能法,水化反应放热量法和物理、化学特征参数法。为正确指导火山灰活性检测方法的应用,本文详细介绍并比较了各检测方法的原理和特点。笔者认为,直接法可直接测定出火山灰质材料与Ca(OH)2反应的程度,但其操作和分析过程相对复杂;间接法可通过测定火山灰质材料对体系物化性能的影响或材料自身的物理、化学特征参数来评价其火山灰活性。本文从材料科学的角度厘清了各检测方法的适用对象,认为应根据不同的火山灰质材料的特性选择与其相适应的火山灰活性检测方法。

土体抗拉强度试验研究方法的综述

土体抗拉强度比抗压和抗剪强度数值更小,因此时常被忽略,造成理论及试验的落后。文中系统归纳了土体抗拉强度的间接和直接方法,对比分析了现有试验方法的优缺点,结果表明:(1)土体抗拉强度的单轴拉伸方法按照力的加载方向可以分为垂直法和水平法,而垂直法中土样破坏前上半部分的重量会影响试验的准确性;(2)常用的土样固定方式有粘结、锚固、摩擦力和夹持,它们各有优势,但夹持较前三者更便捷和可操作。最后,提出水平单轴拉伸试验的后续仍需优化的问题。如制样脱模中土样的损耗、土样受拉段应力分布差,无法适用于大骨料砾质土、土样固定方式繁琐、土样与平台间的摩擦力难以消除等。

1例假性低钠血症的实验室分析

目的通过对1例低钠血症的实验室分析加强临床对假性低钠血症的认识。方法结合患者的疾病史,实验室检查结果,分析方法学检测原理以及更换方法学检测对造成患者低钠血症的原因进行分析。结果患者高蛋白血症干扰间接离子选择电极法对血钠的检测,造成血钠结果假性偏低。选用直接法的血气分析后血钠正常。结论高蛋白血症人群使用全自动生化分析仪检测血钠结果会造成假性偏低,可更换直接法检测,以免造成误诊。

尿素醇解法合成碳酸二甲酯的研究进展

碳酸二甲酯是一种绿色、环保、性能优良的新型有机化工原料及合成中间体,应用范围十分广阔。尿素醇解法是碳酸二甲酯合成法之一,其具有原料廉价易得、过程安全及绿色环保等优点,受到了学术界及工业界的青睐。尿素醇解法合成碳酸二甲酯主要分为直接合成法和间接合成法。目前,直接法因存在转化率低等问题,还未实现工业化应用;然而,间接法合成碳酸二甲酯取得了重大突破,并已有多个企业建成了年产万吨级的生产车间,并投入到工业化生产中。本文对近年来尿素醇解法合成碳酸二甲酯的研究进展进行了综述。

电力系统碳排放计量与分析方法综述

碳排放的准确计量与分析是电力部门实现低碳转型与深度脱碳的基础和前提。该文分析电力系统中碳排放的来源与特性,阐明电力系统中直接碳排放与间接碳排放的含义与区别,说明电力系统中精准碳计量与分析的必要性。在此基础上,分别研究和归纳电力系统直接和间接碳排放的计量与分析方法;对现有相关研究中提出的碳计量与分析方法进行总结,围绕原理、优缺点以及应用现状等方面对不同方法进行对比分析。最后,对电力系统直接和间接碳排放计量与分析方法的发展方向进行展望。相关研究成果可为我国电力系统碳排放计量与分析体系的构建和完善提供参考,助力电力系统的低碳转型。

关于历史建筑进行结构检测的几点建议——以汉口保元里修缮工程为例

从改造设计的角度出发,就历史建筑改造前进行的地质勘察和检测提出了几点建议:历史建筑采用天然基础的,可采用浅层平板载荷实验确定地基承载力;为查明建筑内部实际情况,需对既有建筑物内部布置物探作业;砌体强度可采用直接法和间接法相结合的检测方法,直接法优先采用现场原位检测方法,采用间接法检测时,块体强度采用取样法对回弹法检测结果进行修正;砂浆强度可采用贯入法进行检测,根据灰缝饱满程度考虑强度折减系数,最后根据规范规定的公式推算出砌体抗压强度。

THE COLLOCATION METHODS FOR SINGULAR INTEGRAL EQUATIONS WITH CAUCHY KERNELS

This paper applies the singular integral operators, singular quadrature operators and discretization matrices associated with singular integral equations with Cauchy kernels, which are established in [1], to give a unified framework for various collocation methods of numerical solutions of singular integral equations with Cauchy kernels. Under the framework, the coincidence of the direct quadrature method and the indirect quadrature method is very simple and obvious.

锂离子电池SOC评估方法研究进展

锂离子电池在电动汽车行业中的应用引起了广泛的关注。然而,由于锂离子电池在运行过程中会逐渐老化,这可能导致意外发生,因此需要对锂离子电池进行监管和维护。荷电状态(state of charge,SOC)对锂离子电池的监测和维护起着至关重要的作用。准确的SOC估计可以确保锂离子电池正常充放电并延长其使用寿命。对锂离子电池SOC估计方法进行了总结和分类,介绍了各种方法的原理,总结了其优缺点,并对未来锂离子电池SOC估计方法做出展望。

杂化X射线探测器的优势与进展

占主导地位的X射线探测器主要分为直接半导体型X射线探测器和间接闪烁体型X射线探测器。近年来,杂化X射线探测器通过结合半导体和闪烁体材料的优势而出现。作为活性层的混合半导体和闪烁体导致了不同的工作机制。两相之间电荷/能量转移可以避免闪烁体的余辉效应。并且闪烁体的存在也优化了半导体材料的性能。本文总结了杂化X射线探测器的机制、进展和协同效应,以突出杂化X射线探测器的优势。根据不同的工作机制和各自的特点,我们详细讨论了三种类型的杂化X射线探测器。最后,我们对杂化X射线探测器存在的局限性和未来的发展方向进行了展望。

不同临时冠材料的边缘和内部适合性评价研究

目的:评价直接-间接法制作的不同材料临时冠的边缘和内部适合性。方法:选择2021年1月至2022年1月在安徽医专门诊部就诊的第一磨牙全冠修复患者40例,按照不同制作方法和材料制作临时冠,随机分成4组,每组10颗。利用体式显微镜比较4组临时冠的边缘和内部适合性的差异。结果:不同材料制作的临时冠平均间隙为184.27~229.40μm。间接法CAD/CAM树脂临时冠组的边缘和内部间隙量最小,且符合正态分布。直接法制作的PMMA树脂临时冠的边缘和内部间隙大于间接法制作的PMMA全冠(P<0.05)。结论:间接法CAD/CAM树脂临时冠具有更高的精度,其次是Protemp树脂,直接法制作的PMMA树脂临时冠边缘和内部间隙最大。

遗传算法与鲍尔方向法相结合的频谱参数混合反演方法

为准确获取地下极化体或岩矿石标本的频谱参数信息,结合遗传算法与鲍尔方向法实现了频谱参数的混合反演。该方法首先通过遗传算法搜索Cole-Cole模型参数的近似极优解,而后将其作为鲍尔方向法局部寻优的初始解,再经过多次迭代可准确获取频谱参数。遗传算法与鲍尔方向法的有机结合,既能改善遗传算法局部搜索能力差的不足,又能压制鲍尔方向方法易陷入局部极值的缺陷。数值实验表明,两者结合的频谱参数混合反演方法,具有收敛速度快,反演结果准确的特点。

基于属性加密的可撤销机制研究综述

属性基加密是实现群组通信系统中数据文件细粒度访问控制的重要密码学技术。群组通信系统存在用户加入、退出、属性变更等情况,因此实现用户或属性级撤销的属性基加密是必须要解决的问题。文章在对可撤销的属性基加密方案的分类情况和构造进行研究的基础上,阐述了可撤销属性基加密方案的研究方向和进展,分别从直接撤销、间接撤销和混合撤销3种撤销机制对已有的可撤销属性基加密方案进行深入分析和综合对比,同时指出了可撤销属性基加密机制存在的不足及未来的研究方向。

垄断行为反竞争效果的直接证明方法

直接证明方法和间接证明方法都是反垄断法合理原则第一步骤中,原告证明行为反竞争效果,进而转移举证责任的分析方法。直接证明方法的法理逻辑是,原告如果提供了表明行为实际反竞争效果的直接证据,便没有必要再进行相关市场界定和市场结构分析。相较于间接证明方法的风险和困境,直接证明方法可以简化反垄断分析框架,并且使其更具连贯性。在我国已有实践的基础上完善直接证明方法,需要合理设置适用范围,并且在消费者福利标准下确定实际反竞争效果的考量因素。同时,直接证明方法与间接证明方法之间并不是对立的,保持两者之间的互补性适用是我国现阶段的可行方案。