摘要：In this paper,the CFD simulation and new flow unsteadiness analysis for a single-blade centrifugal pump with whole flow passage were carried *** periodic flow unsteadiness has been quantitatively investigated in detail by defining unsteady intensity and turbulence intensity in both rotor and volute domains under design condition Q=33 L s *** results show that the distributions of flow unsteadiness are the functions of impeller rotating angle and have complex unsteady *** obvious T u fluctuations can be also observed for different impeller *** addition,time-averaged unsteady intensity and time-averaged turbulence intensity were calculated by averaging the results of each mesh node for entire impeller revolution period to evaluate the strength distributions of flow unsteadiness directly and *** accumulative results of an impeller revolution can directly show the positions and strength of the flow unsteadiness and turbulence intensity in both rotor and stator domains which can be an important aspect to be considered in the single-blade pump optimum design procedure for obtaining more stable inner flow of the pump and decreasing flow-induced vibration and *** flow unsteadiness in the side chamber cannot be neglected for an accurate prediction of the inner flow of the pump,and the optimizing design procedure for a single-blade pump impeller will not be accurate using CFD tool if the unsteady flow phenomenon in the side chamber is not considered.

摘要：An OOK-NRZ visible light communication (VLC) system is designed by using a single white LED and a 550 nm visible photodetector. The emitting model of the single LED is established, and the general expression of the detector's output signals under OOK modulation is deduced. With the selected LED, detector and other related parameters, the designed communication system is optimized and its performance is analyzed. The optimized communication distance between the LED and the detector is 0.54 m at the communication bit rate of 1 Mbit/s. With the best communication distance, when the signal-to-noise ratio (SNR) is larger than 6.5 dB, the bit error rate (BER) can drop to 10-4. The analytical model and theory presented in this paper can be of certain practical meanings in the design of similar communication systems.

摘要：A new fabrication technology for three-dimensionally buried silica on silicon optical waveguide based on deep etching and thermal oxidation is presented. Using this method, a silicon layer is left at the side of waveguide. The stress distribution and effective refractive index are calculated by using finite element method and finite different beam propagation method, respectively. The results indicate that the stress of silica on silicon optical waveguide fabricated by this method can be matched in parallel and vertical directions and stress birefringence can be effectively reduced due to the side-silicon layer.

摘要：The design of counter-rotating turbine is one of new techniques to improve the thrust-weight ratio of jet propulsion *** analysis of a low pressure（LP）counter-rotating turbine rotor blade is presented by using ANSYS/CFX *** of aerodynamics and solid mechanics coupling in the computation is *** some rating of turbine,stress distribution and vibration characteristics of low pressure turbine（LPT）blade are *** wake aerodynamic forces and LPT blade vibration are transformed in frequency domain using fast Fourier transform（FFT）*** results show that under wake aerodynamic force excitation,the first order modal vibration is more easily aroused and the higher order response cannot be ***,with different temperature fields,the vibration responses of blade are also different.

摘要：In a centrifugal compressor, the leakage flow through the tip clearance generates the tip leakage vortex by the in- teraction with the main flow, and consequently makes the flow in the impeller passage more complex by the inte- raction with the passage vortex. In addition, the tip leakage vortex interacts with the shock wave on the suction surface near the blade tip in the transonic centrifugal compressor impeller. Therefore, the detailed examination for the influence of the tip leakage vortex becomes seriously important to improve the aerodynamic performance cs- pccia｜ly for the transonic centrifugal compressor. In this study, the flows in the transonic centrifugal compressor with and without the tip clearance at the design condition were analyzed numerically by using the commercial CFD code. The computed results revealed that the tip leakage vortex induced by the high loading at the blade tip around the leading edge affected the loss generation by the reduction or the suppression of the shock wave on the suction surface of the blade.

摘要：This study first investigated cracks on the surface of an actual steel strip. Formulating the Anand model in ANSYS software, we then simulated the stress field in the molten pool of type 304 stainless steel during the twin-roll casting process. Parameters affecting the stress distribution in the molten pool were analyzed in detail and optimized. After twin-roll casting, a large number of transgranular and intergranular cracks resided on the surface of the thin steel strip, and followed a tortuous path. In the molten pool, stress was enhanced at the exit and at the roller contact positions. The stress at the exit decreased with increasing casting speed and pouring temperature. To ensure high quality of the fabricated strips, the casting speed and pouring temperature should be controlled above 0.7 m/s and 1520℃, respectively.

摘要：High-energy rotor uncontained failure can cause catastrophic damage effects to aircraft systems if not addressed in design. In this paper, numerical simulations of three high-energy rotor disk fragments impacting on U type protection rings are carried out using LS-DYNA. Protection rings with the same mass and different groove depths are designed to study the influence of the groove depth. Simulation results including kinetic energy and impact force variation of single frag- ment are presented. It shows that the groove depth infects both the axial containment ability of the protection ring and the transfer process of energy. The depth of groove ought to be controlled to an appropriate value to meet both the requirement of axial containment and higher safety factor. Ver- ification test on high-speed spin tester has been conducted and shows that protection ring with appropriate U structure can resist the impact of the disk burst fragments. The ring is inflated from a circular to an oval-triangle shape. The corresponding simulation shows good agreement with the test.

摘要：A new pressure Poisson equation method with viscous terms is established on staggered grids. The derivations show that the newly established pressure equation has the identical equation form in the projection method. The results show that the two methods have the same velocity and pressure values except slight differences in the CPU time.

摘要：A new Matlab function based on a versatile compensator design approach is *** function allows design of lead-lag, PID, proportional plus rate feedback, proportional-integral plus rate feedback, and nth order linear *** primary inputs to this function are the plant transfer function and the desired closedloop behavior in terms of an nth order transfer *** output is the particular compensator *** unified design approach is primarily based on minimizing a mean-squared error type objective *** minimization gives the compensator parameters in terms of a set of linear simultaneous algebraic *** solution method requires the user to input such parameters as the lower and upper limits of frequency range of interest;such parameters are automatically determined by the use of numerical *** design method and the associated software are demonstrated by solving a flexible satellite problem, and the results are compared with those obtained by two other methods reported in the open literatures.

摘要：An alluvium with a sandy aquifer at the bottom,but lacking an effective impermeable layer between the sandy aquifer and bedrock is referred to as a special alluvial *** by the drainage of the aquifer due to mining activities,a shaft wall in this special alluvial stratum will be subject to a downward load by an additional vertical force which must be taken into consideration in the design of the shaft *** complexity of interaction between shaft wall and the surrounding walls makes it extremely difficult to determine this additional vertical *** a particular shaft wall in an extra-thick alluvium and assuming that the friction coefficient between shaft wall and stratum does not change with depth,an analysis of a numerical simulation of the stress within the shaft wall has been carried *** and size of the additional vertical stress have been obtained,based on specific values of the friction coefficient,the modulus of elasticity of the drainage layer and the thickness of the drainage ***, the safety of shaft walls with different structural types was studied and a more suitable structural design,providing an important basis for the design of shaft walls,is promoted.