Decentralised sampled-data control for large-scale systems with nonlinear interconnections

This paper presents a decentralised sampled-data control technique for a class of large-scale systems, which are considered to consist of linear subsystems and nonlinear interconnections. The decentralised sampled-data controller design problem is established using a closed-loop subsystem. Based on the controller design problem, the stability condition is derived for a closed-loop large-scale system, and the maximum interconnection bound is guaranteed to satisfy the stability condition. Also, its sufficient condition is formulated in terms of linear matrix inequalities. Finally, the effectiveness of the proposed technique is verified by using an example of the multi-machine power system.     

A 2‐in. a‐Si:H TFT‐LCD with embedded backlight control TFT sensors with various channel widths

Abstract— A 2.0‐in. a‐Si:H TFT‐LCD with embedded TFT sensors for the control of the backlight intensity according to the ambient light intensity has been developed. Two types of a‐Si:H TFT sensors with various channel widths were embedded into a TFT backplane with bottom‐ and top‐gate structures for measuring the ambient light and backlight illumination, respectively. The output signal, measured by a readout IC, increased with backlight intensity until 20,000 lux.     

Curie transition and piezoelectricity of the blends of a ferroelectric VDF/TrFE copolymer and PMMA

The Curie transition, even though the conformational change at the Curie transition primarily arises from intermolecular interaction, is highly dependent on the crystallization conditions. A slower cooling rate from the melt during paraelectric crystallization lowers T_c, increases the portion of F_β at the expense of F_α reduction, and produces a more unstable ferroelectric phase. T is rarely dependent upon the amount of PMMA, but T is increased with the PMMA content. PMMA has a favorable action in forming a more stable ferroelectric phase in the P(VDF/TrFE)/PMMA blend and elevating the Curie transition point because of the all-trans sequence conformation of PMMA and a specific intermolecular interaction with P(VDF/TrFE) in the melt state. However, PMMA reduces the total amount of the crystalline phase, the electric response, and the piezoelectricity. © 1993 John Wiley & Sons, Inc.     

Run-to-run control of inductively coupled C2F6 plasma etching of SiO2: Construction of a numerical process with a computational fluid dynamics code

A numerical process to simulate SiO₂ dry etching with inductively coupled C₂F₆ plasmas has been constructed using a commercial CFD code as a first step to design a run-to-run control system. The simulator was found to reasonably predict the reactive ion etching behavior of C₂F₆ plasmas and used to investigate the effects of plasma operating variables on the etch rate and uniformity. The relationship between the operating variables and the etching characteristics was mathematically modeled through linear regression for future run-to-run control system design.     

Subject-based extraction of a latent blog community

In the blogosphere, there exist posts relevant to a particular subject and blogs that show interest in the subject. In this paper, we define a set of such posts and blogs as a blog community and propose a method for extracting the blog community associated with a particular subject. The proposed method is based on the idea that the blogs who have performed actions (e.g., read, comment, trackback, scrap) to the posts of a particular subject are the ones with interest in the subject, and that the posts that have received actions from such blogs are the ones that contain the subject. The proposed method starts with a small number of manually-selected seed posts containing the subject. Then, the method selects the blogs that have performed actions to the seed posts over some threshold and the posts that have received actions over some threshold. Repeating these two steps gradually expands the blog community. This paper presents various techniques to improve the accuracy of the proposed method. The experimental results show that the proposed method exhibits a higher level of accuracy than the methods proposed in prior research. This paper also discusses business applications of the extracted community, such as target marketing, market monitoring, improving search results, finding power bloggers, and revitalization of the blogosphere.     

An approximation by neural networkswith a fixed weight

Neural networks are widely used in many applications including astronomical physics,image processing, recognition, robotics, and automated target tracking, etc. Their ability to approximate arbitrary functions is the main reason for this popularity. In this paper, we discuss the constructive approximation on the whole real line by a neural networks with a sigmoidal activation function and a fixed weight. Using the convolution method, we show neural network approximation with a fixed weight to a continuous function on a compact interval. Also, we demonstrate a computational work that shows good agreement with theory.     

Vibration Control of Wind-Excited Tall Buildings Using Sliding Mode Fuzzy Control

A sliding mode fuzzy control (SMFC) is proposed to design a controller for the third-generation benchmark problem on wind-excited buildings. A distinctive feature in vibration control of large civil infrastructure is the existence of large disturbances, such as wind, earthquake, and sea wave forces. Those disturbances govern the behavior of the structure; however, they cannot be precisely measured, especially for the case of wind excitations. Since the structural accelerations are measured only at a limited number of locations without the measurement of the wind forces, the structure of the conventional control may have the feedback loop only. The general structure of the SMFC, proposed herein, is composed of a compensation part and a convergent part. The compensation part prevents the system from diverging, and the convergent part directs the system to the sliding surface. The compensation part uses not only the structural response measurement but also the disturbance measurement, so the SMFC has a feedback loop and a feedforward loop. To realize the virtual feedforward loop for the wind-induced vibration control, a disturbance estimation filter is introduced. The structure of the filter is constructed based on an autoregressive model for the stochastic wind force. This filter estimates the wind force at each time instance based on the measured structural responses and the stochastic information of the wind force. For verification of the proposed algorithm, numerical simulation is carried out on the benchmark problem for wind-excited buildings. The results indicate that the present control algorithm is efficient for reducing the wind-induced vibration.     

Counterweight optimization for reducing dynamic effects of clearance at a revolute joint

An optimal design formulation is developed to reduce undesirable dynamic effects due to clearance at a joint. The objective function to be minimized is the maximum ratio of the rate of change of the joint force direction ( ) to the magnitude of the joint force (R), i.e. max ( ) as calculated from the nominal mechanism without clearances. Design variables are the magnitude and the location of an added mass attached to each link.

Numerical examples for an offset slider crank mechanisms are considered. To check suitability of the objective function, the initial and optimized systems are simulated dynamically by integrating the system model equations and the phenomena of contact loss compared. It is found that although max ( ) is not a function of the magnitude of clearances and not of dimensionless form, it is a reasonable indicator of the contact loss phenomena for the single clearance system considered. The input torques have also been obtained and compared, shown to be more uniform in the optimized system.