Abstract: According to the requirement of measurement of plantar pressure, this thesis puts forward a plan to construct a new insole plantar pressure system based on multifunction data acquisition modular and Test Point. Then the hardware part and software part are designed and developed respectively. The piezoelectric ceramic type sensors are designed, manufactured and calibrated according to scientific methods. Meanwhile, the DAQ card is selected carefully. Of course, the software part is developed based on Test Point. A series of tests are performed in order to validate the function of the plantar pressure measurement system. The results satisfy the anticipated design requirements. At last, the problems and application trend of the plantar pressure system are predicted.
Abstract: This paper takes metal-insulator-metal system as example and investigates the main types of electrical contact through the view of energy band structure, to analyze the whole process of the transition from ohm contact to barrier contact. Ohm contact, which promotes charges injection from electrode (metal) to insulator, can be used as storage of charge carrier, which is body limited; it can also be regarded as a type of contact that forms an accumulation layer extending from the interface to the interior of the insulator. Whereas, barrier contact is a type of contact which forms a depletion region extending from the interface to the interior of insulator. As for this type of contact, electron injection from metal tends to the state of saturation. The characteristic of neutral contact is that there is no space charge in the insulator, nor band bending, which means the boundary of conduction band and valence band up to the interface is flat.
Abstract: To maintain the ecosystem health and guarantee the social-economic water demand in the Dongjiang river basin, proper management of the water resources is essential. This research introduced the Morlet Wavelet analyses method to investigate the patterns of the past 45 years runoff times series of the main gauges in the Dongjiang River. The general trend and the changing characteristics in both time domain and frequency domain at different scales were revealed. The results were verified by the real part of the Wavelet coefficient and the Wavelet variance. The study discovered that the runoff in the basin exhibited multi-scales of main circle, synchronization and declining. The results could provide valuable information for the management of the water resources and ecosystem of the Dongjiang River.
Abstract: In the ultrasonic gas temperature measurement system, the principle is that the velocity of sound in gas is a function of temperature. But because the propagation speed of ultrasonic wave can be easily affected by humidity, the accuracy of the gas temperature measurement will be affected too. This dissertation will implement the ultrasonic gas temperature measurement system with humidity correction suitable for all kinds of environment humidity. This type of ultrasonic technique is a highly efficient algorithm with the advantages of both time-of-flight method and phase shift method. And the system is realized with a single-chip microcomputer-based with a relative humidity/water vapor pressure meter. The main advantages of this ultrasonic temperature measurement system are high resolution, using narrow-bandwidth ultrasonic transducer of low cost and ease of implementation.
Abstract: Research on the shielding effectiveness (SE) of small shielding enclosures has attracted more and more attention since small shielding enclosures are widely applied in many areas, such as aviation electronics, testing equipment and industrial control. There is still not proper standard to follow for SE tests in a reverberation chamber. The SE of a small enclosure is simulated and measured by moving a field probe along particular positions inside the enclosure using a reverberation chamber.
Abstract: The accurate measurement of the length of steel plate is the key to control technology for cross-cutting production line. Three steel plates determining-length control algorithms were deeply analyzed, in the set-length control strategy fuzzy control technology was introduced, and determining-length fuzzy controller structure and realization was analyzed; In order to improve the accuracy of steel plate crosscut, on the basis of the fuzzy control system self-learning function and artificial self-learning function were increased. Practical applications show that technical advancement, reliability of the control system and shear plate accuracy are high, fully meet the requirements of control.
Abstract: Three-dimension vision coordinates measurement presents many virtues such as high accuracy, flexible construction, simple operation, large measuring range and high measuring speed. So it has become a hot spot of application and research in many fields such as manufacturing, reverse engineering and computer aided surgery. In this paper, a 3D vision coordinates measurement system based on binocular stereo vision and a planar target has been designed and set up. The system’s composing and measuring principles are discussed. The geometric model and detail design of the planar target, which is one of the main factors affecting the system’s measuring stability and accuracy, are presented. A new algorithm for target calibration is proposed. The location and orientation of the planar target can be reconstructed according to rigid geometric transformation. Further results of calibration and measurement are verified experimentally, and a high geometrical accuracy can be achieved.
Abstract: A transformer protection scheme using fault component computed from instantaneous measurement values is proposed in this paper. The algorithm utilizes reactive power directional elements computed from the received IEC 61850-9-2 sampled values, and uses the ratio of active and reactive currents to determine an inrush condition. A transformer fault is declaimed if the directional elements from all transformer terminals seen the fault in its forward direction. Extensive simulation tests show that the proposed algorithm is sensitive to detecting faults, and is able to distinguish faults internal or external to the protected transformer zone, and to discriminate a fault from inrush conditions.
Abstract: In optical measuring system with a handheld digital camera, image points matching is very important for 3-dimensional(3D) reconstruction. The traditional matching algorithms are usually based on epipolar geometry or multi-base lines. Mistaken matching points can not be eliminated by epipolar geometry and many matching points will be lost by multi-base lines. In this paper, a robust algorithm is presented to eliminate mistaken matching feature points in the process of 3D reconstruction from multiple images. The algorithm include three steps: (1) pre-matching the feature points using constraints of epipolar geometry and image topological structure firstly; (2) eliminating the mistaken matching points by the principle of triangulation in multi-images; (3) refining camera external parameters by bundle adjustment. After the external parameters of every image refined, repeat step (1) to step (3) until all the feature points been matched. Comparative experiments with real image data have shown that mistaken matching feature points can be effectively eliminated, and nearly no matching points have been lost, which have a better performance than traditonal matching algorithms do.
Abstract: In this paper, the correction factor is introduced to improve the wavelet packet entropy, which is used to analyze the transient fault current of the series compensated line with Static Synchronous Series Compensator (SSSC). The results show that the wavelet packet entropy when the fault point is before SSSC is much larger than that when the fault point is after SSSC. According to this characteristic, the scheme of identifying fault position for series compensated lines with SSSC is put forward. Cooperated this scheme with the distance protection, the measured impedance of distance protection is adjusted adaptively so that the over-reaching and under-reaching of the distance protection due to SSSC can be eliminated effectively.