Advanced Materials Research Vols. 1061-1062

Abstract: There are some problems existing in open loop system with stepping motor as driving motor, such as lower servo precision, without compensation for step losing of stepping motor and so on. This paper presented a new approach called quasi-close loop control. With the help of the method, the control accuracy will be similar to that of close loop system and can be obtained, and the system will have the same stability as that of open loop system. With MCS-51 single-chip microcomputer as control unit and grating scales for measuring displacement, a quasi-close loop control system was built on NC lathe. The practice shows that the quasi-close loop control system has advantages such as high control accuracy, good stability and high cost performance. It is suited to economical NC machine tools and has wide application prospects.

Abstract: It is serious harm of icing of transmission lines for power system. Deicing robots can replace manual methods, and it is the developmental tendency of transmission lines deice. Recent achievements of the deicing robot were reviewed, focusing on the research of deicing device, which provides technical reference for the design of deicer.

Abstract: The predictions of chaotic time series by applying the least squares support vector machine (LS-SVM), with comparison with the traditional-SVM and-SVM, were specified. The results show that, compared with the traditional SVM, the prediction accuracy of LS-SVM is better than the traditional SVM and more suitable for time series online prediction.

Abstract: A pressure-sensitive tactile sensor is with simple structure, well tolerated material and reliable to meet a variety of applications, particularly easy to realize the structure of the finger sensor that has a biomimetic properties. The characteristics of information collection, and the corresponding supporting technology on tactile reproduction has researched, in order to make the operator aware of the effective electric haptic, and does not appear tinglin. In addition to control the dynamic range of stimulating current, also the waveform, frequency and complete telepresence grasp process are studied.

Abstract: ]:With increasingly serious pollution to surrounding environment,water quality is deteriorating gradually, which on a certain level threats our daily life. In order to detect problems timely, based on FPGA, Multi Parameter Water Quality Online Monitoring System is designed, which, taking Cyclone II FPGA that supports Nios II processor as the core, is responsible for data acquisition, analysis and processing. Data communication adopts General Packet Radio Service (GPRS) to realize the data transmission from acquisition point to the monitoring center. In the analysis of the existing problems of the current water quality monitoring systems, we present the structure and working principle of this system, and then illustrate them from two aspects: hardware and software. Practice shows that the Multi Parameter Water Quality Online Monitoring system with a simple structure is steady, reliable and easy-operated in processing multi-point data acquisition and remote monitoring the whole system, and proves a widely application in the water supply plant of villages and small towns.Key words: FPGA; Water quality; Nios II; remote monitoring

Abstract: This work provides a detection method for failure in rotating machines based on a change of vibration pattern and offers the diagnosis about the operation conditions using Fuzzy Logic. A mechanic structure (as an experimental prototype where faults can be inserted) called Rotating System has been used. The vibration standard of the Rotating System, called "The Spectral Signature", has been obtained. The changes in the vibration standard have been analyzed and used as parameters for detecting incipient failures, as well as their condition evolution, allowing predictive monitoring and planning of maintenance. The faults analyzed in this work are caused due to insertion of asymmetric masses for unbalancing in the axle wheel. The system for diagnosing Fuzzy System was calibrated to detect and diagnose the conditions: normal, incipient failure, maintenance, and danger, using linguistic variables. The frequency of rotation and the amplitudes of vibration of the axle wheel are considered in each situation as parameters for analysis, diagnostic, for the decision by the Expert System based on Fuzzy rules. The results confirm that the proposed method is useful for detecting incipient failures, monitoring the evolution of severity and offering grants for planning and decision making about maintenance or prevention of rotating machines.

Abstract: The scanning acoustic microscope is used to detect the properties of films. The ultrasonic wave propagates in the films with thickness h, acoustic impedance Z₂ between medium with acoustic impedance Z₁. The echoes from upper and lower interfaces overlap and interfere. The echoes are transformed by FFT. The interference phenomena are observed in amplitude spectrum of echoes. The spectrum has periodic extreme values at f_n, f_n=nc/2h. When thickness h is known, sound velocity c₂ of film can be calculated. According to the principle, the properties of films such as thickness, acoustic impendence and elastic modulus are evaluated by scanning acoustic microscopy. The experimental results are good accorded with the actual properties of specimens.

Abstract: The screw pitch error of the ball screw is the primary error source of reducing positioning accuracy during the process of error compensation. When using the laser interferometer compensated the screw pitch error, it was difficult to eliminate the influence of the screw pitch error on the positioning accuracy just by the first compensation .this study proposed the secondary compensation method of the screw pitch error based on the initial compensation. in order to avoid the negative effect of the high prices of the automatic compensation software, the fallibility of the manual compensation and the low efficiency of the manual compensation, this article developed a pitch error rapid compensation software. the experiment result demonstrates that the precision index of the CNC machine tools and the efficiency of compensation can be improved obviously by comprehensive using the secondary compensation method and the pitch error rapid compensation software.

Abstract: The wheel hub detection system produces error inevitably, thus it is necessary to eliminate or reduce such error so that to enhance the measurement precision. Facing the strict requirements on the precision of devices for wheel hub run-out measurement, properties, rules of emerging and contributing factors of such errors were analyzed and results showed that it was necessary to calibrate the laser ranging tester. The input-output relation was learned from the output of such ranging tester too. For non-linear errors emerged, those little errors caused by non-linear issues in actual applications shall be revised so that to reduce detection errors.

Abstract: A skywave radar adaptive frequency selection method based on the preliminary criterion and the weighted criterion is presented. In this method, according to the various operational tasks, the frequency selection criterion is divided into the preliminary criterion and the weighted criterion based on the characteristic of the targets. The adaptive frequency selection of the skywave radar is achieved by the weighted computed of the frequency selection criterion. The feasibility and availability is demonstrated by an example.