Search

The sealing line between two conjugated rotors is a main leakage path in the vacuum pump, however, it is unable to be adjusted before the rotor profiles are determined in the traditional rotor profile generation method. Therefore, a generation method of rotor profiles for claw-type vacuum pumps based on the sealing line is proposed in this paper. The sealing line can be firstly specified as specific segments regarding the characteristics of claw-shaped rotor profiles. By applying the enveloping theory and the cubic spline curve fitting method, the rotor profile is able to be generated from the sealing line. Moreover, the adjustment method is proposed to segmentally correct the shape of sealing line using the quadratic functions by considering the geometric limitations to avoid interference and undercutting in rotor profiles. A three-lobe claw rotors profile is carried out to demonstrate the reasonability and stability of the proposed method.

The internal gear honing is more popular than the external gear honing by its advantages such as higher contact surface and easier correct profile errors. It is usually applied for modifying the gear surface to compensate for the distortions after heat treatment process. However, the lead crowning and anti-twist tooth flank of a helical gear on internal CNC gear honing has not studied yet. Therefore, a novel method for lead crowning tooth flank of work gear surfaces is proposed by using a linear swivel angle function of the honing wheel and a variable pressure angle (VPA) honing wheel is also applied for anti-twist of the crowned tooth flank in honing process.

The effects of dynamic forces and elastic contacts in a pair of intermeshing rotors with the gas-induced cyclic loads based on the multibody dynamics simulation have not investigated yet. The comparison of numerical spectra of time and frequency domains of acceleration with the experimental noise spectrum of an oil-injected twin-screw compressor has not also considered. Therefore, this study proposes a new strategy, which combines the fluctuating torques and forces induced by cyclic gas pressure on the screw rotors to numerically predict vibration response in an oil-injected twin-screw compressor.

It is well known that titanium (Ti) has excellent properties of anticorrosion, biocompatibility and low modulus that would be applied in many clinical applications. The aim of this study wants to increase the hydrophilicity of titanium surface through silanization and then grafted with hydroxyapatite (HA) by hydrothermal synthesis method. Physiochemical analysis of grafting plate substrate was observed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and contact angle analysis. The surfaces with silanization were strongly interaction between SiO2 and TiO2, and thus Ti-O-Si-bonds formed having larger surface areas but only showed a little improved hydrophilicity. The hydrophilicity of Ti substrate was largely increased after the hydrothermal process. Compared with Ti surface without any surface treatment, the surface which modified with hydrothermal synthesis can improve the wettability of Ti surfaces. Furthermore, the Ti surface through silanized modification before hydrothermal synthesis held good calcium phosphate precipitates existing due to the better calcium ion combined ability with polar bond of aldehyde group (Ti-O-Si-CO-).

Using ADAMS software to create a virtual prototype model of luffing mechanism of QY20A crane truck. The entire work process of telescopic arm is analyzed, and the result shows that luffing cylinder lifting force is maximum at the beginning moment. The luffing cylinder force is calculated in different conditions based on the analysis and select the maximum force condition as optimized conditions, make the mathematical model of optimization and optimized using genetic algorithm, which played a guiding role for the of telescopic boom design.

The paper is devoted to a theoretical study of nonlinear wave on a free-surface thin film down an inclined uneven plane. The problem is quite different from that of a viscous films flow along a smooth surface. Thus nondimensional variables are introduced in two ways according to the different relationship of the shallow water parameter and the topography parameter. Further, the zero-order and first-order stream function are derivated on the basis of perturbation method. Finally, the equations which govern the surface height of surface wave on a viscous fluid film down an inclined uneven wall are obtained.

Because of the problems of fault diagnosis in the power electric circuit and the merit of FCM is efficient in clustering and the merit of hidden Markov model (HMM) that have the ability to deal with continuous dynamic signals and the merit of support vector machine (SVM) with perfect classifying ability, With the features extracted from the circuit, based on the trained FCM algorithm, HMM was used to calculate the matching degree among the unknown signal and the circuit’s states, which formed the features for SVM to diagnosis. Double-bridge 12-pulse rectifier is used as a example to verifiy the effectiveness of the method. The experimental results show that the proposed method has a good correct rate.

With the increasingly salient social influence of virtual practice, personalized lifelong learning concept could be realized through network platform. The new learning environment and platform generate the new evaluation system and model. The working experience and features of network learning of the meteorological technical personnel determine the difference between network evaluation model and the traditional summative evaluation system.. The nonlinearity between input vector and output vector also determines the neural network learning evaluation model orientation. The training and simulation show that the network learning evaluation achieves its best effect when the hidden node is 4.

Based on the scale-free networks and combining the characteristics of the independent innovation in network society, mining the key factors affecting independent innovation in network society, establishing the open independent innovation model and algorithm. Through the process of the open independent innovation model, the paper raises the point that the model has the characteristics of small world and scale - free, which can provide reference for the future study.

Knowledge-based Engineering (KBE) should be introduced into the field of mechanical part modeling. The knowledge-based and featured mechanical part modeling is proposed based on the two layers of knowledge base. Features and process planning rules for mechanical parts are integrated and explicit knowledge and tacit knowledge are involved in this model. Explicit knowledge includes basic information, shape feature, precision feature, material feature and assemble feature, and tacit knowledge includes process rule-based reasoning and process feasibility analysis. The model proposed will help to the following process planning and play a very important role to improve the success rate of design mechanical parts. Finally a case study is conducted.

A new model based on multi-scale asperities is established in order to accurately describe flat profile error. After measuring the surface, surface points are projected to each cross-section according to three-dimensional coordinates. Graham’s Scan algorithm is used to search border points of each data set. Then minimum circum-circle is calculated and optimized. Asperity’s radius of curvature and coordinates is calculated by relationship of circle radius and section’s interval. In the assembly process, it is primarily that the peaks on surface actually contact. The contact error plane equation is determined by three asperities which can stability support the other part, so three proper asperities should be searched out firstly. Finally, experimental results show that this model can be applied to calculated contact error.

The effect of waving bottom on the fluid surface wave was investigated. Starting from the basic equations of potential flow theory and boundary conditions, we used the multiple scales perturbation method to deduce fluid surface waves satisfy the first-order approximate equation and second-order approximate equation. Under the second-order approximation, the fluid surface waveform was simulated with the Matlab in the presence of different waving bottom form. The results show that there are three solitary waves on the surface of the fluid. With the development of time, the amplitude of each solitary wave has not changed. It seems that they are not affected each other and propagate independently. So it suggests that the waving bottom is effective for maintaining surface wave energy balance income and expenditure in spreading process.

The government and the power grid corporations pay close attention how to evaluate the peak power load shifting ability of electric thermal storage air-conditioning system scientifically and rationally. The evaluation method of existing standard was analyzed briefly, and a new operable evaluation model based on the field tests was put forward. Based on the above analysis, the peak power load shifting of four projects was analyzed. Example shows that the analysis model can provides the basis for calculating the power load shifting indicator of electric thermal storage air-conditioning project.

Improvement on noise, vibration and wear in silent chain drives is always an important research subject. However, design methods revealed in public are few because the silent chain shapes are variable and complex. A feasible design procedure is extremely required for improving transmission performance of chain drives. Therefore, a novel design optimization procedure for the rocker-joint silent (RJS) chain and sprocket drive is proposed in this paper. The mathematical models of geometry generation, tooth contact analysis and impact velocities at different mesh stages and chain raise amount in the RJS chain drive have been established. Besides, impact velocities and raise amount which may produce ill effects in the chine drive are incorporated as a multi-objective function to carry out the global minimization trying to find out the optimal design parameters for RJS chain drives. The single-objective optimization trends have also been verified with the previous references.

In the paper, with the change of the relation between the Bond numbers and 1/3, the different control equations with different dispersion item was obtained for the surface wave of film under uneven bottom. The equation under tension and bottom was reduced from the potential flow theory with the little parameter perturbation technique, and then was solved by using the numerical method. The waterfall of the surface wave was simulated with Matlab software. The results show that different surface tension and different bottom has different effect on the film surface.

With the development of the heating industry, the higher level of operation and management are required. Therefore it needs more accurate values of nodes pressure and flow. In this paper, based on the genetic algorithm, In order to realize the improved algorithm, change the rate of cross and mutation according to the fitness. After revising the resistance characteristic coefficient, we can get the more accurate values of nodes pressure. Finally, an example is given to verify the feasibility and validity of this method.