Control of stable, integrating and unstable processes by the Modified Smith Predictor

The Modified Smith Predictor (MSP) is designed, and in the literature classified, as a Dead-Time Compensator for integrating processes. In the present paper it is shown that the MSP is a PID controller in series with a second-order filter, defined by the dead-time and an adjustable parameter. Optimization of the regulatory performance of this controller is performed under constraints on the robustness and sensitivity to measurement noise. Excellent performance/robustness tradeoff is obtained for stable, integrating and unstable processes, including dead-time, as confirmed by simulations and by experimental result obtained on a laboratory thermal process.     

Asymptotic stability, ℓ2 gain,boundness analysis,and control synthesis for switched systems: a switching frequency approach

In this paper, several concepts of switching frequency are introduced to analyze the properties and performance of switched systems in infinite as well as finite‐time intervals. The observation is very motivating that different system properties and performances depend on different switching frequencies. Sufficient conditions ensuring asymptotic stability, ?₂ gain performance, and state boundness are derived on the basis of the notions of switching frequency, respectively. Then, on the basis of the analysis results, the control synthesis problems are addressed. LMI‐based design algorithms are proposed to meet different control synthesis requirements. Numerical design examples are provided to demonstrate our results. Copyright © 2011 John Wiley & Sons, Ltd.     

Research of Electrochemical Noise Technology on Corrosion Resistance

This paper is focus on the corrosion resistance property analysis on three electric blasting of the coating-FeAl,FeCrAl,FeCrAlRE by electrochemical noise technology,acceleration of copper acetate salt spray accelerated corrosion test.According to a comparative analysis of three tests coated by the Impedance curve,FeCrAlRE coating power spectral density(SPD)curve and Power curve,FeAl,FeCrAlRE coating has two more notable for the corrosion resistance properties than FeAl,FeCrAl coatings.     

高速公路噪声防治措施分析

论述了高速公路噪声防治工作目标和实施原则,分析了高速公路现有噪声防治措施的特点和适用条件,提出了噪声防治措施方案比选方法,在高速公路的规划、设计中得到了较好的应用。     

An Energy-efficient Switching Scheme with Reduced Switching Transients for a Wind-driven Induction Generator

This article presents a scheme for improving the power output of grid-connected induction generator commonly used in wind energy conversion systems. Generally, the stator of the induction generator is connected in a star with a line voltage of √3 times the rated winding voltage to reduce the line current and, hence, conductor size. To extend the generating operation over a wider speed range, delta-star switchable stator windings are also in vogue. In such cases, the stator is star connected in the lower speed range and switched to a delta connection above a threshold speed. In this study, a new switching scheme is proposed wherein the stator coils are always connected in a star, while the stator is connected to different voltages in low- and high-speed conditions. At low wind speeds, nominal winding voltage is applied to the stator, whereas at higher speeds, the stator applied voltage is √3 times higher than the rated winding voltage. The efficacy of the scheme is demonstrated experimentally with a suitable microcontroller-based switching arrangement. Typical results indicate an increase in output with reduced switching transients. A case study on a 3-Φ, 50-kW induction generator is presented to emphasize the performance improvement with the proposed scheme.     

Stochastic evolution of regulation errors in a boundary-actuated desalination plant

A desalination plant – considered in two configurations (once-through and brine recirculation) – is modelled and controlled using a system of coupled PDEs that describe the desalination processes. The analysis is conducted in two separate parts. First, the operating point of the plant is obtained based on the deterministic process models of the plant. The steady-state distillate production is optimized with respect to a reference pressure head (operating point) that is achieved by applying relatively simple boundary controls. Both deterministic plant configurations are compared in term of characteristic numbers that evaluates the energy-efficient operation of the plant. In particular, those are the thermal ratio and the specific flow rate, where gains of roughly 5.5% and 21.5% are obtained in favour of the brine recirculation plant. The pressure head is subject to turbulence phenomena that disturb its surface so that a deterministic model is an insufficient representation of the real-case scenario. Concerning the second part of the paper, the effects of turbulence are incorporated through stochastic elements given as generalized and cylindrical Wiener processes located on the boundaries and throughout the plant (subdomain), respectively. The pressure head residual is defined as the difference between the deterministic and stochastic system. As both systems are actuated by the same type of boundary controls, the residual field is interpreted as a measure of a regulation error. It is statistical characterization is done spatially by means of the first four statistical moments (sampled) and temporarily with the autocorrelation function. It is found that the applied boundary controls are robust enough to keep the regulation error within tight bounds throughout the whole subdomain of the plant. Throughout the plant, the spatial standard deviation (std) is less than 0.3.     

Study on multi-frequency weak signal detection method based on stochastic resonance tuning by multi-scale noise

In practical engineering applications, useful information is often submerged in strong noise and the feature information is difficult to be extracted. Aimed at the detection problem of multi-frequency signal under colored noise background, a novel weak signal detection method based on stochastic resonance (SR) tuning by multi-scale noise is proposed. Firstly, noisy signal is processed by orthogonal wavelet transform to decompose the signal into multi-scale ingredients. According to the orthogonal wavelet transform coefficients characteristics of 1/f distribution, multi-scale noise is constructed so as to make the frequency-band containing the driving frequency be enhanced through SR system. Thus multi-frequency weak signal is detected. The method is effective to detect multi-frequency weak signal under colored noise background. Experiment signal analysis results show that the proposed method is simple for multi-frequency weak signal detection, and has good prospects for engineering applications.     

Signal noise perturbation on automotive mixed-mode semiconductor device generated by graded substrate defect

The semiconductor technologies evolution allows greatly reducing noise impact on products and many structures have been created to reduce its effect. However, this paper presents the apparition of a noise issue during the production of a mixed-mode device dedicated to automotive applications. The research investigations concerned the fact that failure was not detected at test level but at customer level; therefore, it was determinant to understand the root cause of this failure mode to drive corrective actions in order to secure customer. The challenge was to analyse noise in Failure Analysis (FA) without fault spatial localization results. Indeed, Light Emission Microscopy (EMMI) and Thermal Laser Stimulation (ex: Soft Defect Localization – SDL) were unable to provide any defective area in the product. The lack of failing device identification led us to combine electrical and design analyses in order to define hypothesis on the failure origin. It was then possible to drive physical investigations through different approaches, using physical cross-section, Secondary Ion Mass Spectrometry (SIMS) and Scanning Capacitance Microscopy (SCM) techniques. Finally, the obtained complementary results will be discussed and an explanation of the failure mechanism will be presented as the root cause issue, allowing defining the defective step in production process.     

A wireless multi-channel implantable neural recording microsystem based on optimized analog TDM-FDM combination

Crosstalk noise (CT) is a limiting factor to increase the number of channels in analog Time-Division-Multiplexing (TDM)-based Wireless Neural Recording microsystems (WNRs). This paper proposes a novel approach to mitigate and decrease the effect of the CT by combining TDM with Frequency-Division-Multiplexing (FDM). In particular, we evaluate some possible configurations of the TDM-FDM combination and present a system that has less CT than other configurations. A 12-channel WNR based on the proposed system is designed in both system and circuit-level. In this system, channels are first divided into three 4-channel groups and after multiplexing in time domain, they are combined together with FDM method. While the group containing the marker pulse is located in the base-band, the second and third group are shifted to the frequency domain by employing quadrature modulation. The circuit-level of the system is designed and simulated by using 0.18 μm CMOS technology. The designed circuit consumes a power of 1.4 mW at a supply voltage of 1.8 V. The performance of the proposed system is also compared with simple TDM-based WNR. Simulations shows that in the proposed system the CT is considerably decreased.     

公路噪声源强预测模型研究进展

随着公路建设和城镇化的不断发展，车辆行驶过程中产生的环境噪声对沿线居民、学校的影响也日益明显。针对目前我国的标准规范中未明确给出公路噪声源强预测模型的问题，对国外公路环境噪声源强模型进行系统的分析和总结，并对我国公路噪声源强预测模型的研究提出建议。