Feedback linearizing control of a fluidized bed reactor

The design of an adaptive nonlinear controller for the control of a fluidized bed reactor is derived by using exact linearization techniques. Reset action and parameter adaptation are used to make more robust the precise compensation of nonlinear terms, which is called for in the linearization technique. A nonlinear antiwindup mechanism is introduced to handle reset windup problem and to provide fast response without large overshoot. Simulation results show that the proposed adaptive controller guarantees good setpoint tracking. The developed estimation algorithm allows accurate estimation of the parameters for which the regressor component is not zero.     

Robustness of VS-MRAC with respect to unmodelled dynamics and external disturbances

A variable structure model reference adaptive controller (VS-MRAC) using only input and output measurements was recently proposed and shown to be globally asymptotically stable with superior transient behaviour and disturbance rejection properties. In this paper a singular perturbation approach is used in order to establish the robustness of the controller in the presence of unmodelled dynamics (parasitics) and disturbances. We develop a new Lyapunov-based technique to analyse the overall system and show that for sufficiently small parasitics the system remains stable and the output error is small in some sense.     

LED显示技术的现状和发展

综合介绍了ＬＥＤ显示技术的现状，详细叙述了全色ＬＥＤ显示的关键技术和主要性能，对ＬＥＤ在室内，室外的应用前景作出评述。     

玻璃钢管道的特点,设计原理及选用时的注意事项

本文旨在通过对玻璃钢管道及其标准的发展历史、产品特点、基本设计原理、质量影响因素及选用时应注意的事项等方面的介绍，使用户与工程设计人员对该产品有一个比较全面的了解，以便更好地选用并受益于这种管材。     

Experimental evaluation of a multivariable adaptive nonlinear predictive controller

A new multivariable adaptive nonlinear predictive controller is designed using a general nonlinear input-output model and variable transformations. The controller is similar in form to typical linear predictive controllers can be tuned analogously or by specifying a single parameters for each controlled variable. In addition, the design procedure is computationally efficient. The new controller is compared to a multi-loop proportional-integral (PI) controller with one-way static decoupling and to an adaptive linear predictive controller through tests on a simulated nonlinear distillation column. The new controller performed well in an experimental application to a multicomponent distillation column.     

Low-Power Adaptive Biased Integrated Amplifiers

In this paper the author will present the working principle and the applications of a novel adaptive biasing topology, designed to decrease the stand-by power dissipation without affecting the transient performance of low-power amplifiers. The proposed circuit, whose principle and circuit topology can be implemented both in CMOS and in bipolar standard technologies, gives a biasing current whose value depends on the applied input differential voltage and can be set according to the requested transient performance constraints. The adaptive architecture can be utilized in the design of high-efficient low-power operational amplifiers, for the biasing of both the input stage (where the input source current is dynamically increased) and the output stage (where the output current can be controlled and limited). These amplifiers show a very good behaviour, evaluated in terms of two efficiency factors, if compared with those of other adaptive solutions and class-AB topologies, proposed in the literature. Simulation results and also measurements on a chip prototype, fabricated in a standard CMOS technology, are finally presented.     

一个全数字化交流永磁伺服系统

介绍了开发的全数字交流伺服系统的组成、基本原理及软、硬件结构。通过与模拟交流伺服系统的比较，说明了全数字交流伺服系统可编程能力强、系统稳定性好、系统性能提高等特点。     

An investigation of pore cracking in titanium welds

Two welded Ti-6A1-4V pressure vessels leaked prematurely in service. The leaks were caused by cracks emanating from weld porosity. The cracks originated during fabrication, with subsequent growth in service leading to the formation of the leak paths. Pore cracking is thought to be caused by a mechanism that involves both sustained-load and cyclic contributions, with the former being the more prominent. It is shown that the tendency for cracking is influenced by pore position and that pore size is not a deciding factor in that regard. The factors that govern pore cracking are discussed, and the possible role of interstitial embrittlement is assessed.     

The chloride stress-corrosion cracking behavior of stainless steels under different test methods

Chloride-induced stress-corrosion cracking (SCC) is one of the failure modes of stainless steels. Highly alloyed austenitic stainless steels S32654, S31254, and N08028, and duplex grades S32750 and S31803 possess much improved resistance to SCC compared with S30400 and S31600 steels. With the development of a database, SSData, experimental data collected from calcium chloride tests, autoclave tests, and drop evaporation tests were evaluated. Stress-corrosion cracking data generated by autoclave tests agreed well with the practical service conditions and can be used to discriminate alloys for SCC resistance in sodium chloride solution. Drop evaporation test data can be used in situations where evaporation may occur and cyclic loading may be involved. The SCC resistance of alloys under each method increased with increasing molybdenum equivalent Mo + 0.25Cr + 0.1Ni. For a given alloy, the testing result depends on the stress state and environment; different test methods can give different ranking orders concerning SCC resistance. The performance of duplex stainless steels in a chloride-containing environment at higher temperatures was not as good as expected when dynamic loading was involved.