In order to investigate the tensile deformation and fracture behaviors of a single crystal Nibased superalloy in the temperature range from room temperature to 1100℃，the fracture surface and dislocation configuration after tensile deformation were characterized by scanning electron microscope and transmission electron microscope, respectively. The results reveal that the yield strength and ultimate tensile strength reach the peak value at 800℃，but the plasticity shows a contrary trend compared with the strength. At room and moderate temperature, the fracture mode is cleavage fracture, and changes to microvoid coalescence fracture at high temperature. The main deformation mechanism at room temperature is dislocation shearing γ′ phase, transits from shearing to bypassing γ′ phase at moderate temperature, and changes to dislocation bypassing γ′ phase at high temperature.

n order to investigate the vibration characteristics of vehicle powertrain under road excitation, the centroid vibration acceleration and relative vibration displacement of the powertrain were suggested as the evaluation indexes, and a full vehicle model with 13 freedom degrees containing the powertrain model with 6 freedom degrees was established. The numerical calculation of powertrain vibration states under the excitations of a certain class road profile and engine vibration was performed at the vehicle velocities of 60, 45 and 30km/h. The powertrain vibration characteristics at different velocities were analyzed, and an average fullcourse vibration acceleration method was proposed for the analysis of vibration acceleration. The results show that with the same road profile, both centroid vibration acceleration and relative vibration displacement of the powertrain get enhanced with increasing the vehicle velocity, but the deflection angle of the powerstrain has no significant difference at various vehicle velocities.

To design a CNC machine tool dedicated for prosthetic dentistry, the technological characteristics of denture processing were analyzed using the functional analysis approach. The necessary functions possessed by denture processing machine tool were clearly defined. The mechanical structure of the processing system was constructed, and the performance parameters of some key components in the system were given. Based on the basic theory of the multibody system and according to the actual situation of the investigated machine tool, the volumetric error model for twospindle denture processing machine tool was developed. It is verified that the error of the machine tool is from three line error and three angular error between structural units as well as the vertical error between axes. The present results provide the theoretical basis for adopting the appropriate error compensation strategy and improving the processing accuracy of machine tool.

Aiming at the effect of the construction parameters, such as the arrangement position, arrangement mode and stiffness of suspendome temporary support system, on the structure performances in construction process, the evaluation indexes for temporary support system and the reasonable selecting ranges of construction parameters were proposed. Then by adopting the ANSYS software, the effects of the key parameters on the mechanical behavior of the structure were analyzed, and the reasonable selecting ranges of the parameters were determined. The analysis results show that such key parameters as the arrangement position, arrangement mode and stiffness of temporary support have the evident effect on the performance of suspendome structure in construction process. The proposed construction parameters can provide the scientific basis for the project design and construction adjustment in construction procedures.

The sintering temperature of magnesia foamed ceramic （MFC） is extremely high. In order to decrease its sintering temperature, the fabricating technology of MFC was studied. MgO powder was taken as the matrix powder, and the polymeric sponge dipping technology was adopted to fabricate MFC. The influence of active carbon on sintering temperature was studied. The experimental results show that when the 〖JP2〗mass fraction of active carbon is 01%, the sintering temperature of MFC decreases from 1550℃ to 1500℃,and its bulk density raises from 0.926g/cm³ to 0.977g/cm³. The XRD analysis shows that the addition of active carbon does not change the crystal structure of magnesia. The SEM analysis reveals that there is no residual active carbon in MFC. The results of crude magnesium pouring test show that MFC with adding active carbon exhibits a good filtering ability.

In order to better understand the development trend of Al₂O₃ thermal shock resistant ceramics and to provide design consideration for the preparation of Al₂O₃ thermal shock resistant ceramics, the commonly used thermal shock resistance test methods for the Al₂O₃ thermal shock resistant ceramics, the influence of microstructures, surface conditions and geometric dimensions of Al₂O₃ ceramics on the thermal shock resistance, the feasibility of second phase method to improve the thermal shock resistance of Al₂O₃ ceramics and the research progress on porous Al₂O₃ thermal shock resistant ceramics, were reviewed. Through the addition of ZrO₂, rare earth compounds, low thermal expansion coefficient components or high thermal conductivity components, some mechanical properties of Al₂O₃ ceramics, e. g. bending strength, fracture toughness and elastic modulus, can be enhanced, and as well as(or)the thermal properties of Al₂O₃ ceramics, such as thermal expansion coefficient and thermal conductivity, so as to improve the thermal shock resistance of Al₂O₃ ceramics. Furthermore, laminated Al₂O₃ composite thermal shock resistant ceramics will become a research direction in the future.

Aiming at the electronic structure and thermodynamic properties of metal Al, the theoretical calculation was performed with the firstprinciple based on density functional theory and the CASTEP software. The balance lattice constant, related elasticity coefficients, electronic energy band, density of states, phonon spectrum, phonon state density and related thermodynamic parameters of metal Al were obtained, and the theoretical analysis was performed for the calculated results. The results show that the metal Al has obvious electrical conductivity and good plasticity. The metal Al has three acoustic branch wave dispersion curves and a phonon state density peak. With increasing the temperature, both entropy and enthalpy increase, while the free energy reduces. The heat capacity significantly increases with increasing the temperature, while the heat capacity is almostly unchanged when the temperature reaches 500K. The obtained conclutions are consistent with the laws of physics.

In order to solve the time-varying problem of meshing stiffness in gear dynamics simulation, a spur gear assembly model was established via the involute parametric equation using the 3D modeling software Solidworks, the model was imported into the transient dynamics module of ANSYS workbench, and the comprehensive meshing stiffness was obtained with the quasi-static method. The gear dynamics simulation was conducted with the consideration for gear inertia effect and tooth friction. The results show that the comprehensive meshing stiffness in the actual situation is asynchronous with that computed in terms of theoretical contact ratio. When the gear teeth enter into or exit from the double teeth meshing, the gear vibration is intensified. The impact force occurs when the gear teeth meshing alternates with each other, and the vibration of single teeth meshing is more intensified than that of double teeth meshing.

In order to study the deformation destruction and energy evolution characteristics of sandstone under split Hopkinson pressure bar (SHPB) coupled static and dynamic loads, the related numerical model was established by using LS-DYNA software. On the premise of satisfying the assumption of one-dimensional stress and stress-strain homogenization, the numerical model was simulated and analyzed with the axial and surrounding pressures as variables. The simulation results show that the sandstone dynamic compressive strength shows a linear rate effect when the axial pressure ratio is less than 0.4. Axial and confining pressures lead to compression shear failure and interlayer dislocation failure of sandstone, and have great influence on energy consumption of sandstone, but can hardly affect the change trend of single energy. In the simulation of one-dimensional coupled static and dynamic loads, when the axial pressure is 20 MPa and with the increase of loading strain rate, the energy utilization first increases and then decreases, however, when the axial pressure is 40 MPa, the energy utilization shows a continuous declination. In the simulation of three-dimensional coupled static and dynamic loads, the influence law of surrounding pressure on the energy utilization rate is more complex, showing the overall downward trend in general.

Aiming at the problem that the peak-valley difference of distribution system load caused by electric vehicle charging is too large, a dynamic multi-objective optimization model for the charging scheduling control strategy of electric vehicle was proposed according to the basic change situation of distribution system load. The dynamic multi-objective optimization model was constructed, and two optimal scheduling control strategies, controlling charging power and initial charging time, were proposed. The dynamic particle swarm optimization algorithm was used to solve the model. The simulation results show that the optimal control scheme can reduce the peak load by about 20% after optimization and save the charging cost by 40% to 55%.

In order to apply a new and special chaotic system to secure signals, image encryption, circuit implementation and other fields, a high order four-dimensional hyperchaotic system with 13 terms was proposed. Three-dimensional space and two-dimensional plane phase diagrams were simulated by computers, the Lyapunov exponential spectrum was calculated, and the equilibrium point of the system was analyzed. According to Lyapunov stability theory, a nonlinear anti-synchronization controller was designed. The response system can synchronize with the driving system under the action of anti-synchronization controller. The effectiveness of the controller was verified by the Matlab test platform.

In order to improve the accuracy of handwritten numeral recognition, a deep learning algorithm for handwritten numeral recognition based on the continuous asymmetric convolution structure was designed and proposed. Based on the continuous asymmetric convolution structure and in combination with the extreme learning machine and MSRA initialization, the network structure was designed. With identifying the input image, the CUDA parallel computing and the Cudnn neural network GPU acceleration library were used to accelerate the handwritten numeral recognition. The experiments were performed on the MNIST handwritten digital database. The accuracy of network structure recognition is 99.62%, and the single image recognition speed is 0.005 8 s. The comparison of experimental results shows that both recognition accuracy and recognition speed for the present network structure has been effectively improved.

Full ceramic ball bearings have excellent properties such as light weight, wear resistance, high(low) temperature resistance, corrosion resistance and good accuracy retention, and have broad application prospects in equipment manufacturing, aerospace and other advanced technology fields. The high-performance manufacturing technology system of full ceramic ball bearings has not yet been formed, which seriously restricts its application and development in high-end equipment and has also become a technical problem for the further expansion of the application field of full ceramic ball bearings. Based on the industry's demand for high-end bearing products, this paper analyzes the characteristics and advantages of full ceramic ball bearings, discusses the design methods applicable to these products, summarizes the high-performance manufacturing processes of key components such as ceramic balls and ceramic rings, evaluates the service performance and test technology of full ceramic ball bearings, and forecasts the related technologies and applications.

In order to meet the demand of renovating a conference auditorium at a university into a multiuse auditorium with such functions as concert hall, cinema and theater, the acoustical environment of original building was modelled and simulated with the acoustic design software EASE. Through comparing and analyzing the obtained data, the acoustic defects in original building and the disadvantages in the sound reinforcement system were found out. In addition, the targeted modification and replacement in both decoration materials and loudspeaker system of auditorium were performed, which could make the various relevant data simulated by computer reach the national standard of acoustic characteristics of multiuse auditorium. The acoustic renovation scheme for the ideal multiuse auditorium, which can combine such functions as conference, reporting, film screening and cultural entertainment in one building, can be obtained. 

In order to solve the larger investment problem in testing the whole unit control system of largescale wind turbine before product delivery, the semiobject simulation platform for variable pitch 〖JP3〗system of largescale wind turbine was experimentally investigated. In addition, the solution for the performance〖JP〗 test of variable pitch control system in the factory was proposed. For whole semiobject simulation platform, various operating conditions and load situations were simulated with the software. The operating control system containing the varible pitch control strategy and dynamoelectric variable pitch actuator were taken as object form. Moreover, the test of control performance and actuator as well as the load simulation were completed through the realtime interaction of information. The simulation results show that the case study verifies the rationality of the semiobject simulation test platform, and this method can provide the reliable references and verification means for the design and successive adjustment of wind turbine.

In order to improve the properties of SmFeN magnets, the effects of Sm content, alloy smelting, heat treatment, rapid quenching and hot-pressing on the properties of SmFeN magnets were analyzed. A SmFe alloy was prepared by a smelting method combined with rapid quenching, SmFeN magnetic powders were obtained by ball milling and nitriding, and sintered magnets were obtained by a hot-pressing method. The structure and magnetic properties of samples were measured with X ray diffractometer(XRD), scanning electron microscope(SEM)and vibration sample magnetometer(VSM). The results show that the proportion of each phase in samples is strongly dependent on the smelting method and the heat treatment condition. When the hot-pressing temperature is around 290 ℃, the maximum deformation rate of samples is obtained. Under the condition of 625 MPa and 500 ℃, the bulk density of samples is 6.65 g/cm³, the coercivity reaches about 800 kA/m, and the remanence is about 0.59 T.

In order to study further the crystal structure and elastic properties of ZnS and MgS crystals under high pressure, the phase transition pressure, elastic coefficients （C11, C12, C44） and bulk modulus （B） of two crystals under high pressures were calculated with first principle planewave pseudopotential density functional theory method and through generalized gradient approximation （GGA）. The results reveal that the pressure of phase transition from B3 to B1 structure is 11.87 and 0.78GPa for ZnS and MgS crystals, respectively. The elastic coefficients of two crystals under different structures exhibit the same variation tendency with increasing the pressure, that is, C11>C12>C44. In addition, the structural parameters of two crystals on the groundstate were calculated. It is found that the obtained results are in good agreement with the experimental data and other theoretical results.

To meet the requirement of efficient realization structure and high performance of electronic war receiver, a scheme for digital channelized monobit receiver was proposed. An efficient structure based on WOLA filter banks to realize wideband digital channelized receiver was derived from the traditional STFT algorithm structure. By using the nonconstraint relationship between decimation rate and channel number, the monobit receiving technology was applied in the present structure without data interpolation. Thus, such disadvantages as low instantaneous dynamic range of wideband monobit receiver and frequency resolution limitation of channelized receiver can be avoided. The simulation results indicate that the proposed scheme can improve the frequency resolution of channelized receiver. The hardware realizing efficiency is high, the computing complexity is low, and the instantaneous dynamic range is dependent on the filter shape, which can meet the realtime requirement of electronic war.

Aiming at the current situation that the environmental pollution has become increasingly serious, the effect mechanisms of bisphenol A （BPA） on the hepatotoxicity and reproductive toxicity of mice were investigated. The key enzymes in the blood plasma and liver as well as the sperm abnormality rate were tested, and the pathological changes of liver and testis were observed with the ultraviolet and visible spectrophotometer. The results show that the BPA can significantly raise the vitalities of glutamicpyruvic transaminase （GPT）, glutamicoxaloacetic transaminase （GOT）, alkaline phosphatase （AKP） and glutathioneStransferase （GST）, the contents of both malonaldehyde （MDA） and nitrogen oxide （NO） as well as the sperm abnormality rate. In addition, the BPA can obviously reduce the superoxide dismutase （SOD）, and change the normal microstructure morphologies of liver and testis. Therefore, BPA can not only injure the liver, but also damage the supporting and Leydig’s cells through penetrating the blood testis barrier to disturb the growth, development and energy metabolism processes of sperms, which will cause the damage to the reproductive system.

To solve the problem that the slight pollution of antibiotics in aqueous solution was hard to be removed with the traditional technologies, the degradation tests for residual ciprofloxacin （CIP） in aqueous solution were carried out with the UV technology, and the oxidative degradation rate of CIP was studied. The effect of initial concentration of reactant, pH value of reaction solution, adding dosage of hydrogen peroxide as well as different anions and cations on the removal rate of CIP was discussed. The results indicate that with increasing the initial concentration of reactant, the reaction rate of degrading CIP by UV decreases. When the initial concentration of reactant increases from 1mg/L to 20mg/L, the degradation rate constant reduces from 0.0322min^-1 to 0.0147min^-1. In addition, the neutral pH value is the most suitable condition for gradation. In the UV/H₂O₂ system, the optimum adding concentration of hydrogen peroxide is 1mg/L. The anions and cations have different influence on the degradation of CIP by UV. The reaction degradation constant in anion system shows the order of NO^-₃>SO ^2-₄>CO ^2-₃, and that in cation system exhibits the order ofCa ²⁺>Mg ²⁺>Cu ²⁺, respectively.

In order to solve the problem for accurate localization by using visual SLAM under complex dynamic scenes with fewer effective points, a monocular visual SLAM algorithm was proposed. The perspective transformation matrix between images was estimated by ARANSAC algorithm, and the dynamic feature points in ORB-SLAM2 were distinguished and eliminated by calculating the optical flow values of feature points in estimated images and current frames. Using the dynamic sequence of TUM data set, the as-proposed algorithm was simulated and compared with the ORB-SLAM2 algorithm. The results show that the standard deviation of the absolute trajectory error of as-proposed visual SLAM algorithm reduces by 84.00% to 96.11%, and the optimal standard deviation of translation and rotation drift reduces by 94.00% and 96.44%, respectively, significantly lowering the error of pose estimation by visual SLAM algorithm. The as-proposed algorithm can eliminate the influence of dynamic objects on the localization performance of visual SLAM under dynamic scenes with fewer effective points to improve the localization accuracy.

In order to perform the contrast in the seismic response analysis with response spectrum and time history analysis methods, a calculation model for one common steel frame of multilayer steel frame was established with ABAQUS finite element analysis software. Such seismic responses as the top floor displacement of structure, the maximum displacement between the layers, the interlayer displacement angle and the value of Mises stress of multilayer steel frame obtained with both response spectrum and time history analysis methods were compared. It can be found through the calculation and simulation that the top floor displacement of structure obtained with the response spectrum method is 1.09 times as large as that obtained with the time history analysis method, and the maximum displacement between layers and the interlayer displacement angle of the former is 1.07 times as large as those of the latter. The results show that the seismic responses of multilayer steel frame with both response spectrum and time history analysis methods are conformed to the requirements of specification. The seismic responses obtained with the response spectrum method are bigger than that obtained with the time history analysis method, and the seismic responses obtained with the response spectrum method should be safer. The analysis results can provide the theoretical support for the seismic design of multistorey steel frame structure.

In order to solve the problem that a layer of dense oxide skin will form on the surface of TC4 titanium alloy in the hotforming process, and both surface morphology and thickness of oxide skin are influenced by the temperature, the technology of thermokalite washing and then acid washing for the removal of oxide skin which formed after oxidation at different temperatures was investigated. The surface morphology of oxide skin was characterized with the optical microscope （OM）. The effect of time on the removal of oxide skin was studied, and the hydrogen mass fraction in the TC4 alloy after the removal of oxide skin was tested with the worldly advanced American LECO RH404 hydrogen determination 〖JP3〗instrument. The results show that through adopting the process of thermokalite washing and then acid washing, the oxide skin on the surface of TC4 titanium alloy can be completely removed. Moreover, the hydrogen mass fraction tested with the RH404 hydrogen determination instrument exhibits no significant change.

Aiming at the nonlinear steering system of ship course subjected to unknown external disturbances and uncertain items, an adaptive neural network control strategy based on a disturbance observer was proposed. The neural network was constructed to approximate the uncertain items in ship model. A disturbance observer was developed to estimate the unknown external disturbances and make feedforward compensation for control amounts so as to improve the robustness of control strategy. By using a Lyapunov function, the ultimately uniform boundedness of error signals in the closed-loop system for ship course tracking was proved. The simulation results show that the as-proposed control strategy can force the ship to follow desired course. Compared with the traditional PID controller, the as-proposed control strategy can effectively overcome unknown external disturbances and has strong robustness.

In order to solve the complex hybrid multiple attribute decisionmaking problem of combining such indexes as definite number, grey number and fuzzy number with the increasing, decreasing and constant numerical values, a model for hybrid multiple attribute decisionmaking was established based on TOPSIS method, grey system theory, fuzzy number and membership function. The calculation examples for the performance evaluation of business process reengineering （BPR） were designed. Both validity and feasibility of the model were verified. Moreover, the sensitivity analysis was also carried out for the model. The analysis results show that the model for hybrid multiple attribute decisionmaking can perform the quantitative ordering of candidate schemes accurately. Furthermore, the selection of evaluation indexes in the model plays an important role in decisionmaking.

In order to solve the problem of low comprehensive utilization rate for steel slag and other bulk industrial solid wastes, silica fume (SF) was selected as reinforcing agent and soda residue (SR) was used as partial activator, to activate steel slag (SS) and granulated blast furnace slag (GBFS) for the preparation of alkali-activated steel slag/furnace slag cementitious materials. Basic tests and researches, such as compressive strength, flexural strength, drying shrinkage, freeze-thaw cycle resistance, sulfate resistance and SEM analysis were carried out. The results show that the addition of SR and SF can significantly improve the mechanical properties and durability of cementitious materials. The 28 d compressive strength and flexural strength of alkali-activated steel slag/furnace slag cementitious materials under the optimal ratio are 36.20 MPa and 13.29 MPa, respectively. After 50 freeze-thaw cycles, the mass loss rate is 1.73%; after soaking in 5% Na₂SO₄ for 28 d, the strength loss rate is 2.98%, meeting the 32.5-grade requirements for ordinary slag cement.

In order to investigate the mechanical behavior and deformation mechanism of extruded AZ31B magnesium alloy at high strain rates, the dynamic compression and tension tests were carried out for extruded AZ31B magnesium alloy with the split Hopkinson pressure bar and reflect tension bar apparatus. The average strain rates were in the range from 500s^-1 to 2600s^-1. The microstructural change of tested samples was observed with optical microscope. The results show that due to the formation of basal plane texture in the extrusion process, the tension twins ｛1012｝<1120> are firstly activated when the sample is compressed along the extrusion direction. The yield strength is insensitive to strain rate, and is lower. But at the second stage of plastic deformation, the dislocation slips take part in the deformation, and the strain rate hardening effect is notable. When the sample is elongated along the extrusion direction, the compression twins ｛1011｝<1120> and nonbasal plane slips are the main deformation mechanisms. In addition, the yield strength of the alloy is higher, and the alloy shows a slightly positive strain rate effect. Due to the formation of texture, the alloy shows the intense tensioncompression asymmetry in the tension and compression processes, and the ratio between the compression and tension yield strengths is about 0.32.

In order to solve the problems in the static aeroelastic divergence speed and load redistribution of airfoils for wind turbine blades, the static aeroelastic basic equations suitable for the two dimensional （2D） airfoil sections of wind turbine blades were derived based on the aeroelastic theory within the linear elastic range. Through taking the attack angle as the input, pressure as the output and elastic twist angle of airfoils as the feedback of system, an aeroelastic feedback model for elastic airfoils of wind turbine blades was established. In the operating condition with dangerous wind speed, the computation and analysis for the 2D airfoil sections of wind turbine blades with three kinds of typical airfoils were performed. In addition, the effect of torsion stiffness and distance from stiffness center to aerodynamic center on the divergence speed, additional twist angle and lift force distribution of 2D airfoil sections of wind turbine blades was determined. And the influence of different airfoils on the additional twist angle and lift force distribution of 2D airfoil sections of wind turbine blades was studied. The results show that under the smaller torsion stiffness, the aerodynamic performance of airfoils gets improved to a certain extent with increasing the additional twist angle. When the torsion stiffness is larger, the additional twist angle slightly increases, and has little effect on the aerodynamic performance of airfoils.

In order to more accurately evaluate the residual strength of corroded pipelines with general metal loss, scientifically and reasonably maintain the pipelines as well as enhance the utilization of pipelines, the evaluation method for the residual strength of corroded pipelines with general metal loss based on the API 579 criteria was investigated. Three grades of evaluation for the residual strength of corroded pipelines with general metal loss were performed based on the API 579 criteria. The maximum safe operating pressure of corroded pipelines at the given defects was obtained through the calculation. The pressure value reflects the pressurebearing capacity of corroded pipelines with general metal loss. The experimental results show that based on the API 579 criteria, the reasonable evaluation for the residual strength of corrosion pipelines with general metal loss can be realized.

Aiming at the thermodynamic properties of main strengthening phase Mg₂Si in 6xxx series aluminum alloys, the theoretical calculation was performed with the density functional theory, first principle and CASTEP software. The balance lattice constant, elastic coefficient, phonon spectrum, phonon density of states(DOS)and related thermodynamic parameters of Mg₂Si were obtained, and the theoretical analysis was performed for the calculated curves. The results show that the strengthening phase Mg₂Si has good rigidity and large brittleness, and can play a role of reinforcement in the alloy. From the phonon spectrum and phonon DOS curves, it can be noted that there are nine dispersion relation curves, where three curves are acoustic waves and six curves are optical waves, and the vibration of lattice wave is stronger around 8.51 THz. With increasing the temperature, both entropy and enthalpy increase, while the free energy reduces. When the temperature is below 200 K, the heat capacity significantly increases with increasing the temperature. When the temperature is above 400 K, the heat capacity is close to a constant. Furthermore, the calculated results are consistent with the physics laws.