Combining the reliability-based optimization design theory with the reliability sensitivity analysis method, the reliability-based robust optimization design is extensively discussed. Based on the saddle point approximation theory, the reliability sensitivity formula was derived systematically. The reliability sensitivity was added into the reliability-based optimization design model, and then the reliability-based robust optimization design was described as a multi-objective optimization. Based on the premise that the probability distribution of random parameters had been known, the cumulative distribution function and the probability density function of the limit state function were obtained by the saddle point approximation method, and the result was applied into the reliability sensitivity analysis of machine parts. Finally, the reliability-based robust optimization design was completed. According to the result compared with the result obtained by Monte-Carlo method, it is known that the design information can be acquired accurately and quickly.

In order to quantitatively analyze the beam structural stiffness reliability at different life cycles, it is important to establish the accurate formula of degradation of physical property of beam under fatigue loads. According to influence of cumulative damage caused by fatigue loads on ultimate stress and using the relation of material strength and material elastic modulus, the formula of elastic modulus degradation was deduced based on residual strength degradation model. On this basis, the recursive formula of the beam structural elastic modulus degradation coefficient was given. The residual bending stiffness of beam with circular cross section was put forward. Adequate original data is necessary for probabilistic reliability model and fuzzy reliability model to analyze the structural reliability. To make use of the uncertain information of structures, the uncertain parameters such as initial elastic modulus, the load applied and so on were described as interval variables. Time-dependent non-probability reliability model of beam structural stiffness was established based on interval model. A numerical example has been used to illustrate the proposed method. The result shows that the proposed method is feasible and reasonable and practicable for the beam structural stiffness degradation analysis and the beam structural stiffness time-dependent reliability analysis.

The dynamic characteristics of frame structure of high-speed dynamic balancing machine directly affects the accuracy of the dynamic balance test. In order to improve the vibration characteristic of frame structure of dynamic balancing machine, how the stiffness of the main stiffness rod influences the dynamic stiffness of the machine was investigated. First, the frame structure model of the high-speed dynamic balancing machine was established using finite element analysis software ANSYS and the modal analysis was carried on it. The natural frequency and vibration mode of the frame structure were obtained, removing vibration modes which have no influence on balancing machine. Modal analysis was carried out on different frame structure and the results were compared, aiming to remove structure which had no influence on natural frequency of frame structure. Then, in the simplified model, the dynamic stiffness of five improved models were calculated. The results show that the appropriately changes in the structure size or the material properties of the main stiffness rod will change the dynamic stiffness of the frame structure. In the design process, we can change the structure size or the properties of the main stiffness rod to meet the design requirements. This method has good engineering practice value, and provides analysis method and improvement reference for engineering application．

Solution to the stress of each part of insulators leads to understand of structural performance, and the optimization for each part plays an important role in reducing the construction cost of high-voltage transmission line. this article converted it into a two dimensional problem based on feature of axisymmetric structure of ceramic cap and pin insulator and the nature of axial tension load and the statically analysis was made by ANSYS. on this basis, the results were extracted to establish optimization parameter and made dimension optimization design for the insulator using pin volume as the objective function. the results show that each design parameter and pin volume are reduced slightly, through calculation, the saved steel products consumption each pin is 25.12 g; therefore, it is significant to analyze and optimize insulators, not only verifying structural rationality, but also reducing pin volume, saving considerable raw material and thereby obtaining good economic benefit．

In order to analyze the influence of meshing position, load and rotating speed on the lubrication properties of filtering reducer, an internal-meshing lubrication model of filtering reducer was established, the Newton-Raphson(FEM) method was employed to solve the elastohydrodynamic lubrication equations. The complete numerical solution was obtained by a numerical calculation method with Matlab software. The film pressure and film thickness of lubricant between the two teeth of the reducer at different meshing positions, loads and rotating speeds had been calculated. The lubrication condition of different meshing positions, loads and rotating speeds was analyzed. The effects of meshing position, normal load and rotating speed on lubrication features were obtained. The results show that the values of hydrodynamic film thickness at engaging-in region, engaging-out region and pitch point are different; the thinnest film thickness occurs at the pitch point; the film thickness becomes larger with the increase of rotating speed and the decrease of load. The hydrodynamic pressure also becomes larger with the increase of load, but changes little when the rotating speed increases. 

The performance of thermoelectric refrigerators based on water-cooling method for heat emission was studied both experimentally and theoretically. The cooling performance of refrigerators under different conditions, namely air cooling, the recycled water cooling and the recycled cooling with water at constant temperature, was tested experimentally by using a typical small thermoelectric refrigerator. The experiment results show that water cooling approach is significantly better than the original air cooling method and the cooling effect of the small thermoelectric refrigerator strongly depends on the temperature of the cooling water. The lower the temperature of the cooling water, the lower the cooling temperature is in the end. The small thermoelectric water-cooled refrigerator can achieve refrigerating effect rapidly with water at 17.1 ℃. A theoretical model for water-cooled refrigerators was established, in different temperature constant cooling water conditions, the relationship between temperature changing of semiconductor refrigeration cold end with time was calculated and analyzed. The outcome of the theoretical model agrees well with the experimental results. Our study provides a basis for the performance improvement of thermoelectric refrigerators by using water cooling．

Aiming at the working characteristics of liquid viscosity soft start-up equipment, asking for more larger range of variation of driving torque and output speed of the output shaft, the deformation of output shaft should be located in smaller range, the performance of the output shaft have a major impact to liquid viscosity soft start-up equipment work,the structure of the output shaft needs further analysis. Through establishing the pro/E 3D model of liquid soft viscosity start-up output shaft, using the finite element software ANSYS Workbench to conduct finite element analysis on the output shaft of liquid viscosity start-up equipment, determining output shaft deformation and stress conditions, calculating the modal and fatigue damage of output shaft, simulation results show that the largest damage part of the output shaft is in the coarse side of the shaft keyway, and some improvements are made, providing the reference for structure design and fatigue life estimation of output shaft of liquid viscosity soft start-up equipment. 

 The adaptive growth method of stiffener layout on plate structures is inspired from the growth mechanism of the branch systems in nature. This paper studied the implemental techniques of the design method on the platform of the commercial FEA software ANSYS. The  APDL language was used to program the growth method, and the approach was comprised of three phases, which were pre-process, optimal iteration, and post-process. In the phase of the pre-process, a ground structure was constructed, which included a basic shell structure and initial baby stiffeners. The basic shell structure can be constructed by the modeling module of ANSYS or imported its geometric model constructed by other CAE software. And the initial baby stiffeners were formed by the nodes of shell elements of the basic shell structure. The optimal iteration included seeding, sensitivity analysis and growth, degeneration, and branching. A variable perturbing method was adopted to calculate the approximate sensitivity based on the FEA module of ANSYS. Finally, the post-process phase outputted the optimal structure. Several typical design examples were given to validate the effectiveness of the method, and their optimality of the designed structures were compared with that obtained from the topology design optimization module of ANSYS.

To solve the design problem of identifying the multitone excitation signal for nonlinear system, a design method was proposed for the multitone signal. Firstly, the frequency-domain output characteristics of Volterra series excited by the multitone signal were investigated. Then a comprehensive searching technique was adopted to search the best frequency components, which made the output frequency components of each kernel of the nonlinear system excited by the designed multitone signal don't overlap. Thereby, the conditions for a nonlinear system to be identified were met. With the stimulus signal produced by the proposed method, the top three orders of Volterra frequency-domain kernels can be identified for a target nonlinear circuit. The effectiveness of the proposed method is validated via the simulation test.

In order to improve the service performance and developing speed of the forest fire pump and according to its low-flow, high-head and high-speed professional feature, the performance test system for forest fire pump was designed. The test system adopted open type test device composed by industry control computer, data acquisition module and pump test-bed. It was powered by alternating current electric dynamometer, then drove the pump to work and transmitted the data to industrial control computer for processing. Finally, the new BJL5C forest fire pump was used as an example to conduct the test, the result proved the system was stable and reliable. The test system realizes automated test, with high accuracy, high speed and high transmission rate. In line with the national standards, the test system can meet the forest fire pump's test requirement, and provide guidance on these type fire pump's research and improvement. 

In order to improve the precision of the linear motion part, a new position feedback method using the steel belt transmission was proposed, and a set of position feedback mechanism based on single belt wheel was designed. The modeling and theoretical analysis were presented. When the maximum angle of the steel wheel was fixed, the new kind of steel belt transmission mechanism has many advantages, such as the smaller radius of the belt wheel, the smaller volume, the lighter weight and so on, compared with the usual steel belt transmission mechanism. So the new mechanism has significant superiority in the overall structural design and manufacturing costs of the transmission system. The experimental results show that, when the linear motion stroke is 109.9 mm, the maximum displacement error is 0.006 mm. The linear motion components satisfy the use requirement. The principle of method is reasonable and the structure is compact, simple design, and can be widely used in various instruments．

With the development of space robot technology, the space robot could be used to close and capture the space target. The space three-fingered gripper was developed to help the robot. Using the single and dual fingers, V-shape groove and the interface handle, robot can realize high precision docking capture of big range of pose of moving target. The transmission machine such as worm, bearing and sealing was designed to meet for the space environment. In experiments, in the larger pose migration cases, gripper can capture target and lock in the only pose. So the gripper has higher precision and adapt to the high and low temperature changes,so the developed gripper has the capability of capturing docking target in the space．

In order to reduce the investment cost and pressure loss during operation of steam pipes of modern large capacity thermal power generating unit,the conception of same height design of boiler and turbine was proposed. It means to ensure the elevation of boiler over heater outlet,inlet and outlet of re-heater,main steam inlet and reheat steam outlet of turbine at the same height as much as possible in the design and constructing process of thermal power generating unit. At undulate region, the boiler may be built in lower elevation and the turbine is installed at higher elevation, so the design can be used to guide power plant site selection. If the power plant is built in plain, the method of boiler sinking construction can be used to shorten the length of steam pipes, the energy consumption of construction excavation will be increased, but the energy consumption of coal transportation will be reduced, it is estimated that the energy balance of construction excavation and coal transportations can be achieved in five years. Boiler sinking construction also brings a number of other advantages,such as reducing power plant noise．

Roadway characteristics and bolting can be seen as a non-linear mapping, using the general mathematical methods are difficult to represent non-linear mapping between roadway bolting scheme and its influencing factors. Neural network has been widely used in optimization of bolting scheme and achieved good results. Based on the fact that there existing deficiencies when only using neural networks to predict bolting scheme, the optimization model of bolting scheme was set up combining principal component analysis with neural networks.Principal component analysis was used to do neural network input data pre-processing, which could reduce the input data and make input data unrelated, accelerate the convergence rate of the network,and prediction accuracy was over 90%.The results show that combining principal components analysis with BP neural networks to optimize bolting scheme has a high prediction accuracy. Compared with the single BP neural network,it can improve the precision accuracy．

In order to make the folding bike be ride comfortably and be carried easily,the stress analysis and optimization design for frame,chain box and other major components were made.The “N-bike” bicycle had been folded easily in five times,then the volume became 0.03 m³ and the weight was 5.4 kg. The bicycle frame was “N” font shape and according to the principle of ergonomics,its layout was reasonable.The riding position of the bicycle becomes more comfortable. With more labor-saving transmission,strong practicability,dynamic and stylish appearance, the N-bike is more suitable as a convenient means of transport for cities. 