Abstract:Based on present research status of grinding with surface structured wheels, different methods of structuring wheel surface, including wheels with defined grain pattern, precise controlling grain geometries, innovative grinding wheel structure design and structuring conventional grinding wheels through particular mechanical or laser dressing method are introduced, and the machining mechanism and the influence of grinding with surface structured wheels on the quality of machined surface are analyzed. The mechanism of machining regular texture surface by surface structured wheels is stated, simultaneously the different methods of obtaining regular texture surface are presented. Moreover, the application prospect in the field of special material machining by surface structured wheel is discussed, the development directions of grinding wheel surface structured technology are further forecasted.

Abstract:A microdroplet distribution method based on water condensation on hydrophobic surface is presented to obtain micromanipulation droplet for capillary gripping. Accordingly, the droplet condition required in micro-objects transfer (pick-and-place) is investigated. Model of liquid bridge stretching is established during microdroplet dispensing. Two configurations (plane-plane, plane-sphere) of dynamic liquid bridge is modeled using VOF (Volume of Fluid) method to analyze the acquisition process of capillary micromanipulation droplet. Simulation results demonstrate that the contact angle and drawing velocity have a significant influence on the acquisition fraction of auxiliary droplet and rupture distance. The initial liquid bridge moves toward the surface with small contact angle after the formed liquid bridge rupture. Micromanipulation probes with big drawing velocity enable manipulation droplet to split on two surfaces equally. The impact of droplet volume on the acquisition fraction of auxiliary droplet is relatively small, but is proportional to the rupture distance. Configurations (plane-plane, plane-sphere) of dynamic liquid bridge are experimental investigated to verify feasibility of the proposed method.

Abstract:The aim of this paper is to optimize femoral prosthesis structure and material based on special patient information. Firstly, femoral external and internal contour are extracted from CT data. Femur model and prosthesis model are got respectively and assembled by using 3D reconstruction software, and then the optimized prosthesis structure is developed based on biomechanical analysis results. Secondly, the prosthesis rated load, the life of prosthesis, stress shielding and deformation are determined by the finite element analysis results, and the optimized material matching model is developed based on multi-objective optimization results that are resolved by fuzzy matter-element method. Finally, this prosthesis design method is utilized to a special patient. The optimized structure for this patient is the spheroidic femoral head and individual prosthesis stem, and the optimized materials are the carbon fiber enhanced pek composite for femoral head and Zr-Nb alloy for prosthesis stem.

Abstract:A novel approach for forecasting the periodic demand of spare parts based on feature synthesis is proposed to solve the problem of inaccurate prediction due to many influencing factors of the spare parts demand for construction machines and the demand cycle hard to be selected. The optimal demand cycle length is obtained with the optimization algorithm by defining a similarity measuring model of the spare parts demand sample sets under equal space, and the demand model for spare parts in every cycle period is built by the regression model. Then, a method is presented to integrate multiple cycle demand models of the spare parts into one according to the vector synthesis method in physics, so the optimal demand forecasting model for the spare parts with periodic pattern is obtained by reduction technology. The model synthetically considers the demand forecasting model for the spare parts in every historical cycle and it is great robust and generalized. The prediction model is verified by simulated datasets and the practical data of the demand of round link chains for mining, and experiment results prove that the model has good stability and accuracy.

Abstract:To meet the requirements of driving and mixing on the microfluidic devices for chemical analysis, cell culture, and pharmaceutical test, multi types of AC electrothermal pump with mixing function were developed. A three-dimensional model was built for the study on the qualitative analysis for transport and mixing efficiency of the multi types of AC electrothermal pump with different driving voltages. We found that the electrodes with deflection angles have the best mixing efficiency. The results indicate that the new types of the asymmetric electrodes could have both functions of transport and mixing. At the limited size of microchannel, the electrodes with deflection angles of 25° were more outstanding on mixing than any other types, and the type of the electrodes with deflection angles is the best type in mixing efficiency. The velocity of 69.53 μm/s could be driven at the applied voltage of 7.070 V for this type, and it was 3.5％ faster than the velocity of the traditional micropump with asymmetric electrodes (67.16 μm/s).

Abstract:To deeply understand the changes of char microstructure, the pyrolysis experiments of Huolinghe lignite(HLH), Jixi bituminous coal(JX), Datong bituminous coal (DT) and Jincheng anthracite (JC) were carried out at 25～1 600 ℃. The microstructure information of char was obtained by X-ray diffraction (XRD) and Raman spectroscopy (Raman), of which the relationship was studied. The result demonstrates that the microstructure changes of char have obvious three stages: depolymerization and liquidity, thermal condensation and aromatization, and graphitization. When L_a ＜3 nm, I_D1/I_G and I_D4/I_G increase with the increase of L_a; When L_a>3 nm, I_D1/I_G and I_D4/I_G decrease with the increase of L_a, indicating that the mode of connection and the number of defects are relate to the change of the size of aromatic layers at different scales. L_c is inversely proportional to I_D3/I_G and the total integrated area of Raman, indicating that the amorphous sp² carbon atoms exist in the interlayer of the aromatic layer, which is related to the activity of the aromatic structure.

Abstract:A method on boundary feature extraction of complex surface fitting was proposed due to the fitting optimization during the assembly of auto-body closure parts. The extraction objects, sampling size and searching neighbor were decided based on the fitting boundary features. Point cloud was sampled and constructed by k-d tree. The points within the searching neighbors were projected to their least square tangent plane and the boundary points with fitting features could be extracted by judging the distribution. A case study was conducted to prove the effectiveness and efficiency of this method.

Abstract:To find an effective way for reduction of NO_x emission, this paper made use of a tube furnace to discuss the effects of residence time, temperature, and different catalysts on char-NO reactions. The particle size of char is 1.7～2.8 mm. The results show that the extending residence time is not conducive to the reduction of NO below 900 ℃, and the residence time has a few effects on the reaction at 900 ℃. With the increase of charring temperature, the reactivity for large char tends to be decreasing. But the principle is the opposite pattern—a rising trend in the range form 500 ℃ to 600 ℃. Adding different types of metal catalysts can promote the reduction of NO, the average order of the catalytic activity is Fe>Cu>K>Na>Ca>Mg. The catalytic effect of metal elements in char is affected significantly by temperature, and the metal catalytic ability is different in different experimental conditions. Besides, the characteristics (including volatile content, pore structure and crystalline structure) of char have a great influence on the char-NO reactions. With the higher volatile content, the more developed pore and the lower degree of graphitization, the reduction effect of NO is better.

Abstract:To improve the application effectiveness of single scanning rate method in the coal pyrolysis field, the weight loss data of temperature programmed pyrolysis of Zhundong coal at three heating rates were investigated and the kinetic parameters were calculated using single scanning rate methods. Several problems such as the impacts of segmentation viewpoint and weight loss in the dehydration and degassing stage on the kinetics calculation results, the possibility of obtaining an accurate and unique kinetic triplet and the theoretical significance of kinetic triplet were analyzed. The results show that the selected segmentation viewpoint affects the well-fitted model functions and Arrhenius parameters, the apparent activation energy E values based on sequential conversion viewpoint are obviously lower than those based on independent conversion viewpoint. When the sequential conversion viewpoint is used, excluding the weight loss in dehydration and degassing stage affects the intervals of the other stages and reduces the E values. The comprehensive application of the integral and differential methods as well as the three heating rates can not provide an accurate and unique kinetic triplet, so the theoretical significance of kinetic triplet is limited. Clarifying the pretreatment method of weight loss data and model function chosen are quite necessary for the evaluation and communication of kinetic parameters, and the explanations of pyrolysis mechanism using kinetic triplets should be made with extreme care.

Abstract:In response of the problems such as ammonia escape, high regenerated energy, low absorbed rate in the late stage which exists in the research of carbon capture by ammonia now, this paper presents a kind of reinforced crystallization technologies based on the way of antisolvent crystallization. Reinforcing the aqueous ammonia of low carbonized degree crystallization can make the average absorbed rate maintain at a high level and regeneration by desorbing crystal product can save the regeneration energy, what’s more, the ammonia of low concentration can be chosen as absorbent which can solve the ammonia escape problem at some extent. The bubbling reactor is adopt to do the fundamental research, the effect of different experimental condition on the constituent of carbonized ammonia and the effect of different carbonized ammonia constituents on the crystallization process are analyzed. The experimental conditions of absorption temperature of 20 ℃, flow rate of 2 L/min, CO₂ volume fraction of 28% and aqueous ammonia mass concentration of 10% benefit the crystallization process.

Abstract:This paper studies the trajectory equations of pedals of an inside arbitrary point to all element lines of a cone for solving the problem of cone curve in actual engineering. Based on the feature of a cone and the theory of differential geometry, when the vector from an inside arbitrary point to an element line is perpendicular to the vector of that element line, their scalar product has to be zero, thus the parameter expression of the pedals is derived. After calculated and simplified, the parameter equation of track points shows an intersection track line of the cone and an offset sphere. And the expression in the Descartes coordinate is given. Furthermore, a conclusion is obtained that if there defines a sphere by a diameter from the summit to an arbitrary point in the cone, then lines from the given point to the intersection of that sphere and cone are perpendicular to the intersected conical element lines. Meanwhile, the projection property of the trajectory is studied, and the frontal projection is a parabola, and the horizontal projection is a quadratic curve.

Abstract:To analyze the performance of the piston with thermal barrier coating (TBC), two dimensional cell vertex FVM (CV-FVM) has been extended to the research of the thermoelastic performance of three-dimensional composite structures. The staggered grid technique was adopted to incorporate property variation into the course of solution so as to avoid numerical discontinuity. The unknown variable was defined at the cell vertex, while the material property was defined at the cell center. The developed CV-FVM was used to simulate the thermoelastic fields of the ordinary piston and the predicted results agreed with the ANSYS results. Then, the CV-FVM was used to simulate the thermoelastic fields of the TBC piston and the performance were analyzed. The maximum temperature is in the area between the combustion chamber and the top surface, and the maximum stress is around the interface between the ceramic layer and the cohesive layer. The circumferential stress contributes the main part of the thermoelastic stress in the TBC area. The successful application demonstrates that the CV-FVM can be used as a predictive tool for the thermoelastic analysis of the TBC piston.

Abstract:This paper focuses on the problem that how to build up basic 3 bars tensegrity unit structure and how to judge its stability. Based on the outer shape geometry parameters, using node general coordinates, member vector matrices, connectivity matrices, the mathematical model of basic 3 bars tensegrity unit is presented. To build up structures automatically, a program is established in the MATLAB software by which one can build any basic 3 bars tensegrity structure under the given outer shape geometry parameters. Then, the scalar parameters force densities are introduced. With the connectivity matrices and node general coordinates, the equilibrium matrix function is built. It is linear about force densities. The balance matrix specifies the given system as one of four kinds of structures, and the stable structure can be chosen out.

Abstract:Aiming at the problem of multi-cause process quality diagnosis under the circumstance of information losing, a method based on construction and inference of Bayesian network model is proposed. In the learning process of Bayesian network structure, the thought of score/search is adopted for the assumption structure so as to reduce the learning complexity through the mutual information parameters sorting. In view of the influence of random factors on the diagnostic accuracy, the Leaky Noisy-OR model is adopted, which simultaneously degrades the requirement quantities of data and reasoning. In the end, a problem diagnosis for channel grinding is taken as an example to verify the feasibility and effectiveness of the proposed model and optimization method.

Abstract:To obtain fully isotropic and decoupled structures of parallel robot, a very simple but very effective structural design is proposed based on G_F set. The basic concept of G_F set, algorithms and the type synthesis principle, requirements for rotation based on G_F set are firstly introduced. Secondly the selection criterion of the input pair and type synthesis principle of decoupled branches are given, therefore it ensures that the various branches' input are isotropic and decoupled. According to the type synthesis theory, structural synthesis of 2T2R four degrees of freedom decoupled parallel mechanism is finished. Simultaneously, a lot of new mechanisms are attained. Finally, the screw theory is applied to analyze kinematic characteristic of a parallel mechanism synthesized above. The expression of the Jacobian matrix is deduced which validated the decoupling feature of the mechanism. In addition it demonstrates the effectiveness of the novel method of structural synthesis for parallel mechanisms.

Abstract:To effectively conduct the operating monitoring and malfunction detection of hydro-turbine, this paper investigated the pressure fluctuation characteristics of hydro-turbine running at partial flow conditions, by using the chaos dynamics. Quantitative information of experimental data was obtained. For the pressure fluctuation data monitoring at draft tube, the lifting wavelet transform was adopted to perform the de-noising, hereby, the fluctuation signal distribution on the frequency domain, the energy changing, and the energy partition accounting for the total energy was calculated. Then, for the flow conditions ranging from no cavitation to severe cavitation, the chaos dynamic features of fluctuation signals were analyzed, including the temporal-frequency distribution, phase trajectory, Lyapunov exponent and Poincaré etc.. It is revealed that, the main energy of pressure fluctuations in the draft tube locates at low-frequency region. As the cavitation grows, the amplitude of power spectrum at frequency domain becomes larger. For all the flow conditions, all the maximum Lyapunov exponents are larger than zero, and they increase as well. Therefore, it is believed that there indeed exist the chaotic attractors in the pressure fluctuation signals. Based on the multi-condition analysis, the on-line operating monitoring can be accomplished.

Abstract:To simulate the shape of the pipe and cable in the initial pipe laying operation accurately, a realistic virtual training environment of pipe-laying operation was created. For the initial S-laying and based on the Euler-Bernoulli beam theory, the geometric nonlinear differential equations is established by analyzing the static force of initial pipe laying and cable. To solve the problem of the differential equations boundary conditions, an iterative method based on differential quadrature method is proposed. By simulation and experiments, the shape and variation of the internal force of the pipe and cable under different operating conditions are analyzed, and the accuracy of the algorithm for initial S-laying is proved. The practical example shows that the algorithm can be applied to the initial S-laying effectively. The accuracy of the differential equation is improved and it is easy to be programmed by using this method, which contributes to the preview of offshore pipe laying operation , feasibility analysis and optimization of operation plan.

Abstract:To solve the problems of ‘cold and hot corners’ and slagging on the hot corners when the burners of dual circle tangential firing single furnace boilers are wall-arranged, an innovated burners arrangement is proposed, and numerical simulation is carried out for a 1 000 MW ultra super-critical lignite boiler with Fluent, to acquire the influence of burner arrangements on the furnace flow field and thermal deviation of heating surfaces at the furnace outlet. The results show that the boiler using a half-wall-half-corner arrangement can effectively improve the form of the tangential flow field, decrease the temperature in the central region of front wall, but it also makes the combustion center higher and the temperature at the platen bottom higher. The increase of the airflow rotation momentum leads to the higher tangential velocity, and makes the airflow fields closer to the side walls. Both the uniformity of the flue gas velocity distributions and the temperature distributions near the furnace outlet sections decrease, but the thermal deviation of heating surfaces at the furnace outlet increase, which can be improved by some methods such as over-fire air deflection.

Abstract:To determine the proper values of process parameters when milling the pre-sintering zirconia denture, the optimization calculation is made to increase the material removal rate and decrease the surface roughness by using the ideal point method, minimum deviation method and linear combination method in finish milling process. Taking molar crown upper surface milling as a project for finding the suitable tool path planning method, the path planning is made by UG CAM. The cavity milling following periphery planning method is used for the rough machining. The reciprocating mode of surface milling, following periphery mode of area milling and reciprocating mode of area milling is used for the finish machining. It is found that the better surface quality can be acquired by the method of reciprocating mode of area milling for finish machining according to the results and contrast of the experiment in the same optimization values of the process parameters and standard tools.

Abstract:To guarantee the wheel-arm inspection robot auto-docks with the recharge stand of the solar charging station correctly and reliably, an auto-recharging docking control way is presented, which is based on position relation coarse positioning, visual servo precise positioning and pressure sensor joint feedback. By perceiving the slope information of the place where the robot stands, the charging plug in the pressing mechanism of the robot is moved near the recharge stand in the central bottom of the pensile C type plate. According to the distance between the central seamed edge of the docks in the image space and the central line in the imaging area, the variety of the image features is shown. Charging precise positioning servo control law is designed by adopting variable universe fuzzy control method. The docking state is fed back according to the signal variety of the pressure straingauge sensor under the positive and negative electrodes. The auto-recharging docking control way has been tested in the imitate and real routines, which proves that the method is correct, reliable and effective, and also can satisfy the docking demands of auto-recharging.

Abstract:Aiming at eliminating the disadvantage in current post-processing system which cannot generate the CNC instruction for serial-parallel machine tool, post-processing algorithm, fit for this sort of processing device, was discussed based on XYZ-3RPS serial-parallel machine tool model. By the analysis of structure and post-processing process of the serial-parallel machine tool, the key algorithm of post-processing which includes interpolation algorithm for cutter bit data under Cartesian coordinates, the inverse solution under coordinate of machine tool and the interference checking algorithm were proposed. Meanwhile, some unqualified cutter bit positions were corrected and cutter location data files had been changed into machine tool driver files. Finally, the validity of the algorithm was verified by the processing experiments of vane and sphere.

Abstract:To investigate into the influence of aeroengine assembly condition on the performance of finger seal, an analysis method about the dynamic performance of C/C composite finger seal considering assembly condition is proposed. Firstly, a distributed mass equivalent dynamic model of finger seal with a stack of finger elements is built according to the mechanical behavior between the finger seal and rotor. Secondly, the equivalent parameters are determined, such as equivalent mass, equivalent structural stiffness coefficient, contact stiffness coefficient, frictional force and rotor displacement excitation. Lastly, the dynamic performance of C/C composite finger seal is calculated by the dynamic model, including the leakage rate and the finger stick/rotor contact pressure. It is shown that, in the accordance with clearance fit, no clearance fit and interference fit, the leakage gap of finger stick and the rotor would be decreased, while the contact pressure would be increased. It is reflected that the leakage and wear are two contradictory performance indexes of finger seal. Therefore the structural stiffness of finger stick is changed by structure design under the certain assembly condition. That makes the leakage and wear to be all optimal.

Abstract:To improve the reliability of numerical-controlled machine tool, the reliability and sensitivity of static stiffness of single nut ball screw pair were studied. Based on the Hertz Contact Theory, a model of axial contact deformation was established using the lead, contact angle, nominal diameter of ball screw, raceway curvature ratio, working load and other technical parameters of single nut ball screw pair. According to the principle that the inaccuracy of axial contact deformation for nut ball screw pair is less than the machining accuracy, a nut ball screw pair reliability model was established. The reliability and sensitivity of single nut ball screw pair were analyzed and calculated using the modified first order second moment method. The results show that the static stiffness of nut ball screw pair can be improved by increasing the lead of nut ball screw and decreasing the raceway curvature ratio appropriately, and the reliability of nut ball screw pair can be improved by decreasing the working load to reduce axial contact deformation of nut ball screw pair.

Abstract:An implicit finite volume method (FVM) with Newmark scheme is proposed for the sound propagation problem, and it is used to simulate the propagation of the plane wave. By comparing to the results from the FVM with that of explicit central difference algorithm, the numerical error, stability and computational consumption are analyzed. It is shown that both methods can acquire accurate numerical solutions when λ／Δx≥10. The relative peak error of the implicit scheme is less than 1％ when ω₀Δt≤0.3. With the same time step and spatial step, the numerical result of the implicit scheme agrees better with the exact result. The implicit method treats the absorbing boundary condition more accurate than the explicit method, but it is reverse for the total reflecting boundary condition. The two methods consume similar memory and the explicit method consumes less CPU time.

Abstract:To calculate the process similarity with consideration of deep semantics correlation between business processes, and to optimize the time complexity and matching result when the node number of business process becomes larger and larger, a process matching method based on GA (Genetic Algorithm) is put forward. This method is applied in similarity calculation for both process semantic and process structure, in which encoding is determined, and greedy algorithm is utilized to initialize the population of GA. By defining genetic operations and adopting some strategies for simplifying, the optimization of business process matching with large node number is fulfilled. As is expected, the experiments prove that the overall performance of algorithm proposed in this paper is better than the others that exist, especially when the count of process nodes grows to a large number. So it is concluded that the application of GA in business process similarity calculation and corresponding process optimization can effectively control the time complexity, meanwhile ensure the quality of the matching result, which shows a good practicability.

Abstract:A fault severity level identification method based on ordinal classification is proposed to identify the gear crack levels. The fault level identification is regarded as ordinal classification in which there are ordinal structures between different severity levels and some features have monotonic relationship with the severity levels. The feature evaluation and feature selection for fault severity level identification based on ordinal classification are discussed. Ranking mutual information is utilized to distinguish monotonic features and non-monotonic features of the original feature set, and then a feature selection algorithm is designed for ordinal classification when monotonic features are mixed with non-monotonic features. The experimental results demonstrate that the designed algorithm can select the features with high classification ability for classifying the crack fault severity. A fault severity recognition model is constructed using ordinal classification. The proposed feature selection algorithm can reduce the dimension of feature space, select the features with strong classification ability and improve the accuracy of fault severity level identification.

Abstract:To obtain high quality gear, the machine-tool settings design is studied for HGT hypoid gears. Using local synthesis method as the basis, and based on the machining principle of Gleason hypoid gear, the machine-tool settings are obtained which can satisfy certain meshing performance, and then the tooth contact analysis is done. From the contact pattern and transmission error curve we can see that the gear pairs has big coincidence degree and stable transmission, and its meshing performance can change through the adjustment of local control parameters, so the correctness of the machine-tool settings design is verified. This method can get the optimal machine-tool settings through pre-controlling the meshing condition of the design reference point, and it has a significance for designing high precision hypoid gears.

Abstract:To improve the connection performances of steel-aluminum hybrid lightweight car-body structure, the clinch-bonded hybrid joint technology between steel and aluminum were researched by simulation and experiment. With the A5052 aluminum alloy and Q235 steel as the connected elements and epoxy as the adhesive, cohesive zone model simulating the damage behavior of the adhesive was applied to build up the shear and peel simulation model of the clinch-bonded hybrid joint. On the basis of the experimental verification of the simulation model and multi-objective optimization set by the RSM model for the connection parameters, a Pareto solution about the shear strength and peel strength as well as the optimization combination of the parameters were gained. The results show that the multiple schemes in the optimization solution can ensure the shear strength above 9 400 N, and the peel strength above 700 N. Experiments confirm that the strength of clinch-bonded joints can be twice or more as the sole clinch joint without adhesive, and it can reach 80% of the weld tensile strength of steels under the same conditions.

Abstract:To accurately control molten steel temperature drop caused by turnover ladle and reduce tapping temperature and energy consumption, the heat transfer computation model for ladle was built by using the software Ansys14 and adaptive mesh refinement of ParaMesh2.3. The influence of preheating time before ladle going online, cooling time, online preheating time, offline preheating time and erosion of ladle lining on the thermal storage of ladle and molten steel temperature drop was analyzed. The infrared measured data was used to verify the veracity of the model. The ladle classification table including ladle condition information coding has been built, which was based on calculated molten steel temperature compensation. The research result showed that the molten steel temperature drop varies from 32.0 K to 39.6 K influenced by the preheating time when ladle in the first thermal circulation. The molten steel temperature drop was 47 K when the cooling time was 3 hours with no online preheating. Molten steel temperature drop could be decreased by 3.1 K~6.2 K through the first online preheating for 10 min. The erosion of ladle lining had a big influence on the temperature field of ladle lining but not on the temperature drop of molten steel, and the molten steel temperature drop could not be more than 1K. The ladle classification table can be used to the tapping temperature setting and ladle selecting. The main steel grades tapping temperature in the M steel plant was decreased by 2.3~13.2 K.

Abstract:To solve the problem of uneven distribution characteristic of contact stress with dome pneumatic wheel finishing for large laser hardening mold, a new crown-type pneumatic wheel is designed, and the stress-strain relationship is obtained by the analysis of flexible reformation during the dynamic contact process. By comparing the different stress distribution of dome and crown-type models via finite element analysis and the effect of different compression to different sizes of crown-type models, it comes to the conclusion that the contact area of the crown-type pneumatic wheel is an approximate circular and the stress value performances Gaussian type distribution, which effectively overcomes the contact stress defects of central region with dome pneumatic wheel. The pneumatic wheel finishing experiment with the laser hardening Cr12 mold shows that the optimum amount of compression is 3, 4 and 5mm with diameter 40, 80 and 120mm respectively, and the average surface roughness is 150~160, 65~60 and 30~33 nm. The crown-type pneumatic wheel can effectively improve the finishing efficiency and surface accuracy, and different sizes fit different processing objects.