Advanced Materials Research Vols. 622-623

Abstract: Direct synthesis controller design approach has serious limitations when it is applied to plant models that have more complex models and models involving time delays. In such cases the design becomes more cumbersome and the time delay appears in the denominator making it difficult to realize. In order to get simple realizable controllers approximations of plant model and time delays are done. This leads to controllers with non-optimal parameters. In this paper, a new approach for designing the controller by combining direct synthesis approach and system identification is presented. The controller is identified from the plant model and the desired closed-loop without the need for approximating the plant model and the time delay and ensures that the controller parameters are optimal.

Abstract: In actual application the three-phase gird voltage is unbalanced, but the control strategy of PWM rectifier is always based on balance grid voltage. So the control research of rectifier under unbalance voltage is necessary .In view of the mathematical of rectifier is nonlinear, we will adopt a kind of nonlinear control strategy called Passivity-Based Control (PBC).First based on Symmetric component theory we extract positive sequence of unbalance grid voltage, and then establish the standard Euler-Lagrange (EL) model of rectifier under positive sequence, next we design the system controller based on the PBC theory. Based on passivity of rectifier, we can redistribute the system energy, and improve system performance. Simulation results show that PBC method under unbalance grid voltage is practicable.

Abstract: The Capture Trajectory System (CTS) is an advanced measurement method of the trajectory for store separation in wind tunnel test. According to the characteristics of good real-time, high reliability and a large amount of data processing in the CTS test, an open-architecture measurement & control system based on VXI bus and PMAC2 is proposed in this paper, and its overall scheme design, hardware composition and software structure are described. With IPC, embedded operator and PMAC2 applied, the three level microcomputer structure ensures the system has good real-time and accurate trajectory control. The hierarchical software and the modular design method make sure that the system has good portability, universality and extensibility.

Abstract: In this paper, we propose an optimal voltage control for single-phase inverter with resonant LC filter via type-2 ILQ servo-control by 2nd-order polynomial. The improved ILQ control enables to follow the time-variant sinusoidal reference-voltage without phase delay. The excellent voltage control is achieved through the suppression of resonant output voltage.

Abstract: Gyroscopes are important sensors in motion control in equipment such as airplanes, missiles and Segway. Low-cost gyroscopes have problems in signals such as bias, noise and scaling factor that decrease the efficiency of motion control. Therefore this paper is to present signal conditioning of low-cost gyroscopes using a Kalman filter to remove unwanted noise and nonlinear least square method to estimate parameters for compensation errors to the model by comparison with the encoder. The experimental results is shown that Kalman filter and nonlinear least square method can be used in signal conditioning of low-cost gyroscope for a more accurate signal.

Abstract: A novel automatic ultrasonic system used for the inspection of welds in T nodes is developed, in which a linear phased array transducer using electronic scan is adopted. This paper introduces the testing method of welds in T nodes, and the structure of the whole testing system. Optimization of array transducer has been also pursued based on a mathematical model of acoustic field for linear phased array. The experimental results have proved that the phased array transducer system had the same detectability as that of conventional ultrasonic transducer system, but the component part of the system can be simplified greatly, and the testing flexibility and the testing speed can be improved greatly. It provides an excellent base for the further research and development of the defect inspection of welds in TKY nodes.

Abstract: Atomic emission spectrometry with high accuracy, short lag time, and low detection limit, it has been widely applied in various fields. The application of atomic emission spectrometry in the converter steelmaking process has an important significance to improve the smelting of speed and steel quality. This article describes the principle of atomic emission spectroscopy (AES) analysis. Spectra obtained by the experimental for qualitative analysis, detected molten steel containing titanium element.

Abstract: Many studies have successfully applied near infrared (NIR) spectroscopy to estimate important wood properties. In this paper, the use of NIR (350–2500 nm) spectroscopy to predict the cellulose crystallinity of Poplar (Populus nigra var.) was investigated. The calibration and test models were constructed using partial least squares regression (PLS). The correlations were significant both the calibration and the test samples using six factors, and the correlation coefficients (R2) were 0.9367, 0.9472 respectively. The results suggest that NIR spectroscope may provide a useful tool for rapid and accurate prediction of the cellulose crystallinity of Poplar.

Abstract: Several cracks were found on some actual floating roofs of a crude oil tank in the oil refinery located in southern Japan. We assumed that one of reasons would be due to thermal stress caused by temperature changes during the day. In order to consider whether the thermal stress could the cause damages on the floating roof, strain and temperature were measured on the actual floating roof by using optical fiber gauges. Furthermore, fracture possibility due to thermal stress was calculated to discuss whether thermal stress could cause fracture or not. As a result, the probability showed that thermal stresswasnot enough to cause fracture. Anotherexternal factor such as Typhoon could be related.

Abstract: Thermal conductivity and thermal stability plays a vital role on the performance of NAO brake pads . The Steel fiber a semi metallic composition is carried out in this paper to prepare the Non Asbestos Brake Pad. Steel fiber has good thermal stability and bulk density. So the optimization of steel fiber percentage for thermal behaviour is considered using TGA. The temperature rise during brake application will be between 150-400⁰ C and this zone of temperature is very critical to determine the fade characteristics during friction testing. Less weight loss between 150 – 400°C during TGA testing means that it is a better thermally stable product. Hence, three different friction composites were developed with same formulation varying the steel fiber content with the inert filler namely barites and designated as NA01, NA02 and NA03 respectively. After the fabrication of the friction composites, the TGA test revealed that the composite NA01 had minimum weight loss during 160 - 450⁰ C. The composites were then tested for Tribo performance using Constant speed testing machine following SAE J 661a standards. Thus we can correlate the thermal stability with the stability of friction based on minimum weight loss using TGA testing. Hence composite NA01 proved to be the best performer.On another aspect the NA01 has more rotor wear when compared to the other composition in that aspect of rotor wear NA03 is best.