In this paper, we first discuss the direct scattering problem for a cylindrical homogeneous elastic tube with a geometrical method, and then study the inverse problem. The heuristics of B-F procedure (Best-First search strategy ) is used. The inner radius, outer radius, sound velocities of the tube and sound velocity of the internal medium are obtained with this heuristics.
As for the problem that reactive power optimization computing speed are slow for large-scale power systems,multi-area parallel calculation is an effective solution. Based on Ward equivalent technique,this paper supplements and improves the decomposition and coordination algorithm for multi-area reactive power optimization. The reactive power optimization parallel calculation model of equivalent partition is established,and the implementation principle of parallel calculation based on Ward equivalent partition is summarized and analyzed. Then,the parallel coordination calculation mode and parallel calculation flow,which are suitable for multi-area reactive power optimization based on Ward equivalent technique,are given. The reactive power parallel optimization calculation is implemented by using Matlab parallel computing platform. Finally,testing results on IEEE 39-bus,real 538-bus systems and real695-bus systems validate the correctness and effectiveness of the proposed algorithm in comparison with the centralized optimization method.
This article describes the work of office design for low-class highway design how to use the HintCAD software for low-class highway survey and design features.
With the increase in the main spans of cable-stayed bridges, the wind-induced vibration, especially the high-mode vortex-induced vibration (VIV) of the long stay cables has become a concern for many researchers. In this study, to investigate the high-mode VIVs of stay cables via wind tunnel tests, the mode order amplification factor (MOAF) of the stay cable was proposed to design the flexible stay cable model with a relatively large-scale ratio (λRe) of the Reynolds number (Re). Furthermore, the wind-induced vibration characteristics of the flexible stay cable model with a smooth surface for wind yaw angle (β) of 0° were investigated. In addition, the β effects on the wind-induced vibration characteristics of the stay cable were studied. Finally, double-helical fillets were applied to suppress the high-mode VIV responses of the flexible stay cable model for different β. The results showed that the flexible stay cable model that was designed by the proposed method of MOAF satisfied the similarity of the prototype stay cable and the damping ratios (ξ) of the first several modes of the flexible stay cable model were from approximately 0.021% to 0.064%. The stay cable exhibited five in-plane VIVs in the test wind velocity (V) range for β = 0°. Furthermore, the maximum amplitude of the displacement of the in-plane VIV of the flexible stay cable model decreased with the increase in the VIV mode order. The significant in-plane VIV responses of the stay cable were observed for β of 15°, 30°, −15°, −30°, and −45°, respectively, and the in-plane vibration acceleration responses were significantly larger than the out-of-plane vibration acceleration responses of the flexible stay cable model. The VIV responses of the stay cable could be effectively suppressed through the double-helical fillets with a diameter (d) of d = 0.10 D (where D = diameter of the stay cable) and pitch (P) of P = 12 D.
The paper presents a design of low power high precision ultrasonic heat meters.The MSP430 was used as MCU of the heat meter,the time measurement chip TDC-GP21,a Time-to-Digital converter,was used to measure the ultrasonic upstream propagation time and downstream propagation time,the PT1000,a platinum thermistor,was used to measure the water temperature at inlet and outlet.It starts with hardware design after investigating the principle of ultrasonic heat meters,and completes software programming based on the hardware design.Moreover,the accuracy and stability of the ultrasonic heat meters in paper can be verified by the actual test results.
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