Finite-time adaptive fuzzy control for a class of output constrained nonlinear systems with dead-zone

The article investigates the finite-time adaptive fuzzy control for a class of nonlinear systems with output constraint and input dead-zone. First, by skillfully combining the barrier Lyapunov function, backstepping design method, and finite-time control theory, a novel adaptive state-feedback tracking controller is constructed, and the output constraint of the nonlinear system is not violated. Second, the fuzzy logic system is used to approximate unknown function in the nonlinear system. Third, the finite-time command filter is introduced to avoid the problem of “complexity explosion” caused by repeated differentiations of the virtual control signal in conventional backstepping control schemes. Meanwhile, a new saturation function is added in the compensating signal for filter error to improve control accuracy. Finally, based on Lyapunov stability analysis, all the signals of the closed-loop are proved to be semi-globally uniformly ultimately bounded, and the tracking error converges to a small neighborhood region of the origin in a finite time. A simulation example is presented to demonstrate the effectiveness for the proposed control scheme.     

异烟肼衍生物对聚L-乳酸性能的影响

以异烟肼和均苯三酸为原料合成了新型均苯三酸三异烟肼,考察了其对聚L-乳酸(PLLA)结晶性能和热稳定性的影响。结果表明:均苯三酸三异烟肼起到了异相成核的作用,能有效提升PLLA的结晶速率,其中添加质量分数2.0%的均苯三酸三异烟肼可使PLLA有最大非等温结晶焓,但过量的均苯三酸三异烟肼却不利于PLLA的结晶。均苯三酸三异烟肼的加入不会改变PLLA的热分解行为,但随着均苯三酸三异烟肼含量的增加,其起始分解温度下降。     

砖混结构混凝土现浇板墙内留缝法防治收缩裂缝

砖混结构建筑物中混凝土现浇板裂缝已成为质量通病。为解决这一问题，可采用墙内留缝法：将现浇板的墙内部分人为分隔开，板钢筋仍需穿过，与两端板相连，这样可以减少水平约束，有利于混凝土现浇楼板自由收缩，从而有效避免了收缩裂缝的出现。     

Global stabilisation for a class of upper-triangular nonlinear systems with unmodelled dynamics and time-delay

This paper considers the stabilisation control problem of upper-triangular nonlinear time-delay systems. One distinct characteristic of this work is that the systems contain unmodelled dynamics, unknown control coefficients and time-varying delay, which make the control design much more difficult. By modifying the homogeneous domination approach and introducing a gain-scaling method, a new controller is constructed such that all the states of the closed-loop systems are bounded and convergent to the origin. Simulation examples are given to illustrate the validity of the theory.     

Au/NaYF4 : Yb,Er Binary Superparticles: Synthesis and Optical Properties

Colloidal superparticles (SPs) are nanoparticle (NP) assemblies in the form of colloidal particles. Assembling nanoscopic objects into mesoscopic or macroscopic composite architectures allows for the bottom-up fabrication of functional nanomaterials. In this study, a method for single-step self-assembly synthesis of Au/NaYF₄ : Yb,Er SPs was developed using oil-in-water (O/W) microemulsions to simultaneously encapsulate gold nanoparticles (AuNPs) and NaYF₄ : Yb,Er upconversion nanoparticles (UCNPs) via evaporation at room temperature. The synthesized Au/NaYF₄ : Yb,Er SPs possess good dispersibility and stability. When the number of AuNPs added is increased, the SPs exhibit decreased upconversion luminescence, which can be ascribed to the Förster resonance energy transfer (FRET) from the NaYF₄ : Yb,Er UCNPs to the AuNPs. Time-resolved measurements of the green emission further confirm the existence of a new decay route corresponding to the FRET process. Our research provides a facile and versatile strategy for the synthesis of novel multifunctional nanocomposites with tunable upconversion luminescence properties, which can be of great significance in biological applications.     

Global practical tracking for stochastic time-delay nonlinear systems with SISS-like inverse dynamics

This paper investigates the practical tracking problem of stochastic delayed nonlinear systems. The powers of the nonlinear terms are relaxed to a certain interval rather than a precisely known point. Based on the Lyapunov-Krasovskii (L-K) functional method and the modified adding a power integrator technique, a new controller is constructed to render the solutions of the considered system to be bounded in probability, and furthermore, the tracking error in sense of the mean square can be made small enough by adjusting some designed parameters. A simulation example is provided to demonstrate the validity of the method in this paper.     

各相关领域实用的六类电离辐射量

为适应核科学和电离辐射技术的日益广泛应用,电离辐射量体系一直在不断演进。本文根据各种电离辐射量的实际应用场合和主要特性,归纳整合为六大类各相关领域实用的电离辐射量(包括有关衍生量)加以评述,旨在从方便实用出发,有助于各相关领域人员更好理解和正确应用有关的电离辐射量及单位。     

Removal of DDT in drinking water using nanofiltration process

The removal of DDT[(1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane)] with synthetic waters was carried out on a nanofiltration (NF) pilot unit. The influence of initial DDT concentration, pH, flux and recovery on the removal of DDT was studied. The presence of humic acid and some inorganic (CaCl₂, NaCl, and CaSO₄) matters was also tested in the experiment. The removal percent and that of their adsorption on the membrane have been calculated. The results reveal that DDT was easy to be adsorbed on the membranes and the higher the applied pressure the more rapidly saturation of the membrane was achieved. At the initial concentration of 77 μg/L, the equilibrium for DDT adsorption can be achieved in 30 min. With the initial DDT concentration from 5 to 20 μg/L, the removal percent was from 95 to 85%. On condition that recovery was not changed, higher flux can lead to low rejection of DDT. On the other hand, low recovery can have a high rejection when the fluxes were the same. Humic acid can hinder DDT from passing through the membrane by adsorption and inorganic matter (NaCl, CaCl₂ and CaSO₄) can improve the removal percent by reducing the pore size of the membrane.