Abstract:Lower implement ratio of gear strength standard still occurs in the industrial applications, which results in lack of generality for the design of gear products based on different standards.Comparative analysis of contact and bending strength using ISO 10300-2014 and ANSI/AGMA 2003-B97 standards for spiral bevel gears is carried out, which is verified by finite element contact analysis in this paper. The differences for the definition and evaluation methods of the design parameters and the correction factors between the above two standards are investigated. The effects of geometrical and working parameters of a spiral bevel gear pair on contact and bending strength are illustrated subsequently and discussed briefly. The results show that the maximum contact and bending stresses calculated by the two gear standards are largely deviated, which are closely relative to the definition and evaluation methods of the design parameters and correction factors. Furthermore, the comparative results of finite element contact analysis and the calculation results from the gear standards indicate that the fatigue strength limit of gear material and the gear strength are necessary to be included simultaneously. These results also show that a more reasonable determination of load capacity in spiral bevel gears is attained according to the safety factors of contact and bending strength.

Abstract:This study aimed at exploring the design guidelines of restraints system parameters for occupants in oblique crash under car to car collision. The full car finite element model of a compact car was used to conduct the 30° oblique impact, and the model of occupant restraint system in the driving area were established and validated. The sensitive analysis of restraint system parameters to the driver in target car and driving car was then carried out. These parameters included seat belt parameters, airbag parameters and safety seat parameters. Furthermore, restraint system parameters were optimized according to these sensitive injury parameters. It is showed that the driver’s head and chest injuries are sensitive to the locations of D-ring, anchor and buckle in the 30° oblique crash. Meanwhile, the femur forces are sensitive to the locations of anchor and buckle. Further, the driver injuries in both the target car and driving car are sensitive to airbag fire time, pretensioner fire time, airbag holes areas and mass flow rate of the airbag. After the optimization, the injury index WIC of driver of target car is induced by 33.7% and that of the driver of driving car is induced by 7.4%. The optimization results make the protecting effect of the restraint system for drivers both in target car and in driving car to be optimized.

Abstract:To realize the lightweight design of the Formula Student China's (FSC) frame structure, the geometry optimization is performed with the concern of modal, strength and stiffness constraints. Firstly, a finite element model of the frame is built based on the FSC rules. Subsequently, five types of static characteristic analysis conditions, five types of stiffness analysis conditions of important parts and six free modal analysis conditions are conducted for performance analysis of the frame structure. The size optimization model is set up with minimizing mass as the objective, the allowable stress of materials, allowable stiffness of important parts and excitation modal of the engine as the constraints, and the frame tube thickness as the design variable. Finally, approximate solution is acquired by sequential linear programming with nonlinear optimization model. A good lightweight result is obtained. The weight of the FSC frame decreases by 5.34 kg with a reduction rate of 15.7%.

Abstract:The traditional finite element (FE) modeling method of manually generating high-quality mesh is very time-consuming. In this study, a method of identifying and extracting landmarks automatically was proposed. 9 years old child's C4-C5 cervical spine based on mesh morphing was developed rapidly. A scaling method was used to calculate the material properties of 9 years old child's C4-C5 cervical spine. The morphed FE model was validated by 9 years old child's post-mortem human subject data under the conditions of stretch, flexion and extension. The analysis results showed that the time for landmarks selection was reduced by 2/3 to 3/4 through the automatic method in comparison to the traditional method. The mesh quality of the morphed FE model was of higher quality and was close to the baseline FE model. The mean geometric error was 0.46 mm. The simulated output value of the model was in good agreement with the experimental value, and the accuracy was over 90%. This proposed method can save large amount of time for identifying and extracting landmarks and can develop the morphed model with high biomechanical fidelity. At the same time, the method shows a strong adaptability and can be applied to the finite element modeling of various complex geometries.

Abstract:Research progress of monitoring engineering ceramics grinding by acoustic emission (AE) is firstly described. It is found that the study of grinding diamond wheel wear monitoring is normally based on the analysis of the root mean square of acoustic emission signal, and the accuracy of acoustic emission monitoring is not high. In order to promote the accuracy of acoustic emission monitoring for wear states of grinding diamond wheel, support vector machine is applied to establish the classification model of grinding diamond wheel wear states. Through the analysis of acoustic emission signals, it is found that the strongest spectral energy of alumina ceramic acoustic emission signal under precision grinding is in 30~40 kHz band. The AE signal spectrum of the diamond grinding wheel wear states including mild wear, serious wear and after dressing are significantly different. The wavelet decomposition coefficient variances of the grinding acoustic emission signal can well reflect the wear states of the grinding diamond wheel. Therefore, the wavelet decomposition coefficient variances of grinding acoustic emission signal is applied as the input characteristics of support vector machine to identify grinding diamond wheel wear states, and the accuracy of classification test is 100%.

Abstract:In order to investigate the effect of ultrasonic assistance on the microstructure and properties of 2219 aluminum alloy welded joint, the butt welding test on 3 mm thickness 2219-T87 aluminum alloy plate was carried out by ultrasonic assisted friction stir welding method. The microstructure, mechanical properties, three?dimensional deformation measurement, fracture scanning and XRD were studied. The results showed that the tensile strength was increased by 8.48% and the fracture strain was raised by 9.25% owing to the addition of high frequency ultrasonic vibration to the friction stir welding technology. At the same time, it also effectively improved the upper and lower inhomogeneity of the microstructure of the welded joint, and increased the size of weld bottom cross sections. Particularly, the formation of the defects was inhibited at the bottom of the weld, which can improve the overall strength of the weld. Through the XRD test, it was confirmed that with the decrease of welding temperature, the degree of dissolution of the main strengthening phase θ ″ and θ ′was reduced, and the coarse θ phase particles’s aggregation extent reduced after the addition of ultrasound to the friction stir welding, which improved the mechanical properties greatly.

Abstract:To realize the rational prediction of system friction torque in the design phase and improve the correctness of performance prediction for the actuator, taking the electronic mechanical brake (EMB) actuator with planetary gear and ball screw as the study object, the main source of system friction and its influence on the EMB actuator were analyzed. Firstly, the dynamic model and friction torque model were established according to the structure and load of EMB. The prediction of the friction torque model was compared with the experimental results, and the reason of the difference between the experimental and predicted results was discussed. Based on the dynamic model and friction torque model, the influence of parameters in the friction torque model on the gap closing time and maximum clamping force was studied. The energy dissipation during braking with the maximum clamping force was calculated. The proportion of the friction torque at each component and the influence of rotation rate and clamping force on these friction torques were analyzed. It was found that the frictions which influence the gap closing time come from ball screw and motor, while the frictions which affect the capability to clamp are generated by ball screw, motor and thread bearing. With the increase of the clamping force, the influence of the frictions due to ball screw and thread bearing increased significantly, while the impact of friction from motor decreased greatly. During emergency braking, the effective torque transfer ratio was 73.56%, and the energy dissipation ratio was 48.1%.

Abstract:Aiming at the problems remaining in the gasoline direct injection (GDI) engines such as high pressure fuel pump noise and low dynamic response in high pressure fuel rail, the driving current in the pump spill valve is optimized and a control strategy of pump fuel quantity is designed to reduce the work noise of high pressure oil pump and also to shorten the dynamic response time in high pressure fuel rail. When the throttle opening increases from 20% to 50% and target fuel rail pressure from 6.5 MPa to 9.3 MPa, the dynamic response time is only 4 s. Therefore, it is concluded that the method is feasible, and it provides the reference value for optimization of engine fuel injection control system.

Abstract:The load-displacement characteristic curves of C-series disc spring with outside diameter of 28 mm under different working conditions were obtained by static loading test with microcomputer controlled electronic testing machine. Based on the ABAQUS finite element software, the finite element model of disc spring was established and the numerical simulation was carried out under different displacement loads. The numerical models were tested and modified using the experimental data. The modified model agreed well with the measured results. On this basis, the finite element model of non-standard grooved disc spring was established, and the load-displacement characteristic curve and stiffness-displacement curve of the disc spring under different slot positions and different slots were calculated. The effects of different slotting positions and slotting modes on the disc spring load variation range, stiffness change rate, stiffness variation range, negative stiffness zone size and maximum equivalent stress were analyzed. This study has a certain reference value for the design of non-standard grooved disc spring and the application of negative stiffness element on the vibration isolation device.

Abstract:In the process of analyzing crack growth with traditional finite element method, crack tip singularity is an urgent problem that must be faced with, and then the direction and length of the propagation are closely related to the mesh of model. In this paper, a model that is not thoroughly dependent on the mesh and can be used for analyzing problems of crack growth is set up. Because interaction integral method can relieve the effects of singularity to some extent, severe requirements for meshing caused by singularity can be avoided. Stress intensity factor at the crack tip is solved by interaction integral via finite element method, and direction of the propagation is determined by the maximum circumferential tensile stress theory. When cracks propagate, only the meshes of concerned areas are regenerated in order to obtain the final extension path in a relatively precise way. At last, several typical examples, including growth of mode-I crack, cracks with a hole plate and cracks subjected to compression, are compared with references. Reliability of the method in this paper is verified and applicability in many damaged patterns is shown as well.

Abstract:For the phase-to-phase short circuit fault occurred in transmission lines without shunt reactor, a method of adaptive sequential reclosure is proposed in this paper. A circuit model is built for analyzing the phase-to-phase short circuit fault, and the time domain expression of terminal voltage is deduced for the open-phase at different stages of transient fault. The recovery voltage characters of terminal voltage at open-phase is analyzed in detail. The theoretical analysis shows that the phase angle difference of terminal voltage at open-phase changes suddenly from -120° to 180° in the moment of arc extinction, and the decaying DC component appears obviously in the recovery voltage after the arc extinction. According to the above characteristics of terminal voltage at open-phase, a criterion was proposed to detect the arc extinction time and realize the adaptive sequential reclosure of transmission line. The simulations verified the correctness of the analysis result and the validity of the proposed method.

Abstract:In terms of the problem that the suppression of impulse noise (IN) in orthogonal frequency division multiplexing (OFDM) based power line communication depends on the characteristic parameters and sparsity of IN, this paper proposed a suppression algorithm based on compressive sensing (CS) and False-Alarm probability. In this approach, the projection of IN is observed using OFDM zero carriers, and the rough estimation of IN is carried out by using the method of base pursuit denoise (BPDN). Then, an adaptive impulse noise detection threshold based on false alarm probability is designed, and the support set of IN is obtained according to the designed threshold. Finally, the IN in power line communication is reconstructed by the least square method. The original OFDM signal can be derived by subtracting the estimated IN from the received OFDM signal. The simulation results show that the proposed algorithm can reconstruct the IN well even if the sparsity conditions of IN is unknown, the performance of the algorithm is superior to the traditional compressed sensing and the nonlinear denoising methods, and this algorithm is reliable and effective for mitigating IN in broadband power line communication.

Abstract:Conventional chaotic optimization is a sensitive initial values algorithm with low search accuracy and slowness of convergence. Besides, convergence of harmony search algorithm is not stable and its adaptability for the multi-objective optimization problems is poor. Therefore, a multi-objective hybrid algorithm based on parallel chaos optimization and harmony search algorithm (MOCOHSA) is proposed in this paper. In the MOCOHSA, the global search ability of parallel chaos optimization and local search ability of harmony research are utilized, and adaptive operation is introduced in the harmony search algorithm. In this way, the MOCOHSA has good search speed and convergence performance for multi-objective optimization problems. The proposed algorithm performs better than other multi-objective optimization algorithms for the optimization of 8 multi-objective optimization test functions. Finally, the algorithm is used to solve the satellite heat pipe design problem.

Abstract:The rapid and accurate reliability assessment technique is critical to the improvement of distribution network operational level. A reliability evaluation method of distribution network based on load classification is proposed in the paper, which uses probabilities and sampling approach to determine the operating state of the system and the place where the fault or failure occurs. The distribution system is divided into different types of loads for analysis, and the functions of network reconfiguration and load transfer are taken into account under the case of distributed generation. This method can effectively simplify the traditional reliability evaluation process and improve the efficiency of analysis. It can be also suitable for the real-time reliability evaluation of the distribution network. The validity of the proposed method is verified by the improved IEEE-RBTS Bus 6 system as an example.

Abstract:According to the structural features of power system stabilizer PSS4B, a hybrid PSO algorithm is applied to PSS4B parameter optimization in this paper. By connecting RTDS analog input/output interface card with NES6100 excitation regulator, the semi-physical simulation system is constituted, and the single machine infinite model is established on RTDS real-time digital simulation platform. Based on testing the phase frequency characteristic without compensation of generator excitation system and after parameter optimization, PSS4B critical gain experiment, step response test under load, short circuit disturbance test and inverse-regulation effect test are carried out in turn. The test results show that the optimized PSS4B can suppress power oscillation well in the different frequency bands, and have good inverse-regulation suppression effect.

Abstract:To solve the problem of sheets counting in the printing industry and so on, the count measurement method based on machine vision is proposed. Image acquisition system is built by using the latest high-resolution CMOS camera and megapixel, low distortion of the fixed focus lens. Aiming at the problem of detecting low contrast stacked sheets, a local histogram equalization algorithm and a linear enhancement based on bi-Gaussian second order are proposed. The algorithm is divided into the following parts. First, to improve the speed of the algorithm, only part of the image, which is obtained from image acquisition platform, is selected as processing area, and wavelet de-noising is performed. Second, the preprocessed image is enhanced by the local histogram equalization. Then, the detecting of the stacked sheets is acquired by using second-order derivative of bi-Gaussian and mean filter processing in the horizontal and vertical directions, respectively. Finally, the counting result can be acquired by the peak detection, and displayed in time. Experimental results show that the error rate of the count measurement method is less than 0.01% for the various types of sheets (including the 0.05 mm pure white sheets). It can also save a lot of manpower and material sources. Therefore, it deserves being promoted and used.

Abstract:The main technical bottleneck in the research of on-line inductive wear particles monitoring sensor lies in the contradiction between the sensor sensitivity and channel diameter. The sensor with high sensitivity generally adopts the micro-flow channel structure, leading to a small maximum allowable flow rate, while the sensor with large channel diameter has markedly lower sensitivity. To satisfy the requirements of online wear condition monitoring of heavy machinery, the sensitivity improvement method of large aperture inductive abrasive particle sensor is studied. It is proposed to make the sensor work in full resonance state, in which the excitation coil works in the parallel resonance state and the induction coil works in the series resonance state so as to jointly enhance the sensor output induced electromotive force caused by the wear particles. For the detection mechanism, a perturbation model of magnetic field caused by wear debris in the alternating magnetic field is established, which considers the eddy current effect of particles in alternating magnetic field and improves the practicability of the model. The experimental results show that the resonance mechanism largely increases the sensitivity of the sensor, which can successfully detect up to 75 μm ferromagnetic particles and 220 μm non-ferromagnetic particles, and satisfy the online monitoring requirements of initial abnormal wear stage of the heavy machineries.

Abstract:To support the high proportion grid interconnection of renewable energy power generation such as wind power and photovoltaic, this paper integrates the wind power plant (WPP), photovoltaic power station (PV), convention gas turbine (CGT) and pumped storage power station (PHSP) as the multi-power Hybrid System (MPHS), and establishes a WPP-PV-CGT-PHSP stochastic scheduling optimization model based on robust stochastic optimization theory. First, this paper introduces the basic structure of MPHS and establishes a multi-power output model. Then, based on the optimization goal of system operation economic benefit maximization and output power fluctuation minimization, the MPHS scheduling operation multi-objective model is established. Simultaneously, to overcome the uncertainty impact on the system, this paper presents an uncertainty characterization method of wind power and photovoltaic based on predictive power, transforms the constraints containing uncertainty variables into the constraints reflecting the decision makers’ risk attitude, and then forms MPHS stochastic scheduling optimization model. Finally, WPP with 9.6 MW installed capacity, PV with 6.5 WM installed capacity, 3 CGT and 1 upper reservoir with 10 MW·h equivalent capacity are taken as the simulation system. The simulation results show as follow: 1) MPHS can make full use of the power generation complementary characteristics of different energy, and achieve optimal overall system operation results. 2) PHSP can optimize and adjust the operational behavior to provide greater capacity for wind power and photovoltaic grid connection. 3) The introduction of robust coefficients can provide scheduling decision-making tool for different risk-preference decision makers, minimize the operational risk during chasing the maximum economic benefits.

Abstract:Defense lawyers accountability for binary system has its historical evolution of the origin and the professional theory foundation, the reform is difficult to adapt to a defense lawyer scale expansion and identity change, lead to a defense lawyer criminal responsibility for frequent responsibility and administrative responsibility and discipline to distinguish the unknown aspects of realistic foundation. Outside of the defense attorney accountability paradigm comparison, the dominant modes of American court, Germany's jointed dominant mode, and the Japanese bar exclusive mode is worth reference, the all China lawyers association fully autonomous is lack of universality, which shall enjoy the right of some regulation reflecting the modern country under the rule of law, it is the basic principle of decentralized management. Defense lawyer accountability for the reform path of binary system including the binary system of judicial reform, implement macro regulation and micro accountability for relatively independent effective connection, discipline, responsibility and administrative responsibility. Necessary defense lawyers undertaking civil compensation should be brought into the regulatory system, it is realized from the dual system to quasi ternary system transformation, promoting the defense lawyer system of accountability for three-dimensional.

Abstract:In order to deal with the problem of the explosion of the signal level input stimuli space in the massive design, a high level structural stimuli generation algorithm and corresponding functional coverage model targeted at bus system are presented. Firstly, the bus system is abstracted to be a general bipartite graph model (BGM), and then, the mathematical model of the stimuli is established. Consequently, a general layered equivalence partition algorithm of ISS and the relevant high level functional coverage model are proposed. Finally, two structural stimuli generation algorithms based on the search of ISS tree are presented. Experiments are performed in the functional verification of bus system of IME-Diamond SoC. The result indicates that the high level functional coverage model can help uncover functional bugs more easily when compared to code coverage, and structural stimuli generation can reduce 96% stimuli for coverage convergence when compared to random stimuli generation.

Abstract:The Imperial Palace is a representative Chinese cultural symbol. The documentary creation related to it has always been an extremely important part of the historical and cultural documentary creation in China. Since the new century, the changes in the concept of history, the development of media in the market, the strengthening of international cultural exchanges, and the spiritual guidance of “national revival” have made the documentaries of the theme of the palace exhibit obvious changes in terms of narrative objects, structural design, and expression techniques. Through an analysis of several representative documentaries, this article will clearly sort out its evolution path and deeply think about how documentary can tell a good story of the Imperial Palace .

Abstract:By the Delphi method, this study calculated the frequency of full score and used the analysis method based on the AHP of Index Number Scale, establishing the evaluation criteria for the intangible cultural heritage micro-blogs. then it, using Arithmetic Average, calculated the Matrix and analyzed the relevant weights of all the indexes and screened out of 34 intangible cultural heritage micro-blogs to assess, showed online behaviors of the intangible cultural heritage micro-blogs originated from the offline activities, showing the characteristics of the online behaviors which were typically triggered by the offline ones; the spread of intangible cultural heritage micro-blogs was only limited among small groups who participated in the activities related to intangible heritages. Accordingly, the ways to disseminate intangible cultural heritage micro-blogs should be expanded through their intermediate, technological and data integration. That is how the synergetic management and service can be achieved in cross-class, cross-regional, cross-system and cross-sector ways.

Abstract:This paper proposed a novel phase detector structure that prevent the effect of metastability,and using a inverted delay line structure to reduce its area.The structure was implemented in SMIC 65 nm low leakage tech node inside an all digital DDR PHY which can work in frequency from 100~400 MHz.The total area is 4 298 μm2 and the DLL has a area of 2 350 μm2,chip testing results shows the IP works as expected.And since its all digital,the design also has good transplantability.