Discrete‐time sector based hands‐off control for nonlinear system

This article presents a hands‐off control design for discrete‐time nonlinear system with a special type of nonlinear sector termed as “discrete‐time sector.” The design method to define the boundary of a discrete‐time sector is done with control‐Lyapunov function. The generalization of nonlinear system is viewed in the perspective of a comparison function. By means of a proposed sector, a switching control is designed such that no control action is experienced inside the sector thus, saving unnecessary control efforts. However, to study the robustness for discrete‐time system, a hands‐off control is modified to ensure the monotonic decrease in the energy of the system. Finally, the proposed approach is verified with the simulation results.     

Systematic convergence of nonlinear stochastic estimators on the Special Orthogonal Group SO(3)

This paper introduces two novel nonlinear stochastic attitude estimators developed on the Special Orthogonal Group with the tracking error of the normalized Euclidean distance meeting predefined transient and steady‐state characteristics. The tracking error is confined to initially start within a predetermined large set such that the transient performance is guaranteed to obey dynamically reducing boundaries and decrease smoothly and asymptotically to the origin in probability from almost any initial condition. The proposed estimators produce accurate attitude estimates with remarkable convergence properties using measurements obtained from low‐cost inertial measurement units. The estimators proposed in continuous form are complemented by their discrete versions for the implementation purposes. The simulation results illustrate the effectiveness and robustness of the proposed estimators against uncertain measurements and large initialization error, whether in continuous or discrete form.     

Distribution-free composite Shewhart-GWMA Mann-Whitney charts for monitoring the process location

The Mann-Whitney (MW) statistic is one of the most recommended two-sample statistical tests when the assumption of normality fails to hold due to its robustness and fascinating properties especially when small sample sizes are involved. In order to improve the sensitivity of the generally weighted moving average (GWMA) monitoring scheme toward the detection of large shifts, in this paper, a new distribution-free phase II composite Shewhart-GWMA (CSG) scheme is proposed using the MW U statistic. The performance of the proposed scheme is investigated using the average run-length (ARL) and average extra quadratic loss (AEQL) values through extensive simulations. The performance of this newly proposed monitoring scheme is found to be superior when compared to numerous memory-type MW schemes (some existing and others introduced in this paper) in many situations. An illustrative example is given to demonstrate the implementation of the CSG MW U scheme using real-life data.     

Asymptotic stability of general linear methods for systems of linear neutral delay differential-algebraic equations

This paper is concerned with numerical stability of general linear methods (GLMs) for a system of linear neutral delay differential-algebraic equations. A sufficient and necessary condition for asymptotic stability of GLMs solving such system is derived. Based on this main result, we further investigate the asymptotic stability of linear multistep methods, Runge–Kutta methods, and block θ-methods, respectively. Numerical experiments confirm our theoretical result.     

新疆沙漠砂密实度划分研究

通过对沙漠砂进行的大中型槽原位测试模拟试验研究 ,建立了静力触探和标准贯入试验指标与砂土密实度间的经验相关关系 ,分析了现有规范应用到沙漠砂中的一些弊端 ,并提出了一套工程实用的沙漠砂密实度的划分标准。     

工业废料磷石膏的工程特性试验研究

对大量作为工业废料堆放的磷石膏进行材料试验，即级配试验、击实试验、三轴试验和压缩试验，研究其压缩特性和强度特性及影响其力学性能的因素，探讨了其作为地基处理时的换填材料的可行性。     

水力压裂中多孔岩体的等效弹性常数应用

水力压裂调研结果认为，地下岩体中所含随机分布孔隙能够影响水力压裂的造缝过程。将多孔岩石的孔隙简化成规则排列的球形孔洞，采用渐近均匀化方法建立了等效弹性常数随孔隙比变化的关系；与基于Budiallsky自治理论得到的有效弹性常数进行比较，两曲线能较好地吻合；为水力压裂法准确地预测出水力压裂的造缝结果提供了可行方案。     

沥青混凝土面层施工中的质量控制

从沥青混合料、运输、摊铺、碾压这四个方面，介绍了沥青混凝土面层施工质量控制中应注意的几个问题，以提高沥青混凝土面层的压实度和平整度，确保路面的施工质量。     

混凝土密实度的雷达检测方法

混凝土的密实度是混凝土耐久性及抗渗性的一个重要指标.由于探地雷达检测具有无损、检测速度快、扫描面积大、效率高等优点,故作者尝试用探地雷达对混凝土的密实度进行检测.针对三种不同外观质量的混凝土路面,对其密实度进行了雷达扫描检测,发现雷达图像有明显差别.并利用渗水性检测仪,对这些路面的抗渗性作了现场测试.结果表明,两种方法的结论是一致的,这表明探地雷达对混凝土的密实度检测,是一种可行的方法.