In this paper, classical molecular dynamics simulations were used to explore the impact of deposition temperature and bias voltage on the growth of Al2O3 thin films through magnetron sputtering. Ion energy distributions were derived from plasma mass spectrometer measurements. The fluxes of deposited particles (Ar+, Al+, and O−) were categorized into low, medium, and high energies, and the results show that the films are dominated by amorphous Al2O3 at low incident energies without applying bias. As the deposition temperature increased, the crystallinity of the films also increased, with the crystals predominantly consisting of γ-Al2O3. The crystal content of the deposited films increased when biased with −20 V compared to when no bias was applied. Crystalline films were successfully obtained at a deposition temperature of 773 K with a −20 V bias. When biased with −40 V, crystals could be obtained at a lower deposition temperature of 573 K. Increasing the bias enables the particles to have higher energy to overcome the nucleation barrier of the crystallization process, leading to a greater degree of film crystallization. At this stage, the average bond length between Al-O is measured to be approximately 1.89 Å to 1.91 Å, closely resembling that of the crystal.

In order to improve the current-carrying properties of AgCu10 alloy, AgCuS-carbon nanotubes (CNTs) composite coatings were synthesized on AgCu10 substrates using an in-situ sulfide method. During the process, an entangled CNTs layer was formed firstly on the AgCu10 substrate by dipping the substrate into a CNTs dispersant and dried at room temperature, then an AgCuS-CNTs coating was synthesized in-situ by immersing the substrate with the CNTs layer in a 0.1 M Na2S solution. The current-carrying friction performance of the composite coating was significantly improved. Compared with the AgCu10 substrate, the friction coefficient was decreased from similar to 0.35 to similar to 0.15, and the wear rate was reduced by 2 orders of magnitude. Furthermore, the electrical resistivity of the coatings was as low as 2.44 x 10 (-6) Omega center dot cm, which was almost the same as the AgCu10 substrate.

为得到更大速度适用范围的钨合金球形破片侵彻低碳钢板弹道极限速度计算模型,分析不同着靶速度下钨合金球形破片侵彻低碳钢板的侵彻破坏特征,建立了包含弹、靶主要力学参数的弹道极限速度计算模型,模型系统考虑破片刚性、塑性、侵蚀以及破碎侵彻等情况;根据模型求解需要,针对钨合金破坏特征建立对应速度阈值的计算方法;基于已有试验数据,应用信赖域方法获得模型系数,建立弹道极限速度计算模型;开展破片对Q235、Q345 E钢板弹道侵彻试验,根据试验结果分析模型的计算精度.结果表明:该模型计算结果较试验结果平均误差和最大误差均低10％,较现有弹道极限速度计算模型计算结果平均误差减少了60％.

Aiming at the geometric errors that affect the machining accuracy of CNC machine tools and the errors caused by cutting forces, the homogeneous coordinate transformation matrix of each component with errors relative to adjacent components is derived by using the principle of homogeneous coordinate transformation, and 21 geometric error elements and 35 cutting force error elements in the machining process of three-axis CNC milling machine are identified. Because the NC machine tool in the process of machining can be regarded as a new transmission chain, one end of the chain is the tool of the machine tool, and the other end is the workpiece to be machined. According to the relationship that the coordinates of the theoretical cutting point of the workpiece and the theoretical cutting point of the tool are the same in the basic coordinate system of the machine tool, the mathematical model of the comprehensive error in the machining process of the NC machine tool including geometric error and cutting force error is derived.

螺纹连接是侵彻弹体与引信体连接的主要形式之一,直接影响着弹体与引信系统振动响应特性.针对现有数值仿真手段难以准确表征螺纹连接的问题,提出用薄层单元模拟螺纹连接的有效方案,结合理论与试验研究建立薄层单元材料参数的确定方法.基于螺纹连接弹性模型与薄层单元理论推导出薄层单元的材料参数;将薄层单元材料参数传递到有限元模型中进行建模,通过螺纹管以及弹体与引信系统模态试验对薄层单元模型的计算结果进行验证.结果表明:与不同螺距及不同旋合长度螺纹管模态试验结果比较,薄层单元模型计算误差最大为5.11％;与节点融合建模方式比较,弹体与引信系统采用薄层单元建模方式进行计算后,前3阶模态频率最大误差从17.72％下降到2.54％.

Vanadium dioxide (VO2) has attracted a great interest in energy saving and smart coating applications because of its promising thermochromic properties. Generally, high luminous transmittance (Tlum) and good modulation capability of solar energy (ΔTsol) are desired. However, most experiments report that they have an antagonism relationship, meaning that it is difficult to improve both simultaneously and the point turns to find a balance between them. In this work, we put forward a novel perspective on the design of VO2 films. Ab initio calculations are associated with experimental results by finite-difference time-domain (FDTD) method. The refractive indexes of the rutile-like metal phase (R-VO2) and the monoclinic insulator phase (M-VO2) provided by ab initio calculations are imported into the FDTD simulations, where a series of configurations with various thickness are constructed. The simulation transmittance spectra of VO2 films are well consistent with our experiment results, of which the VO2 films are fabricated by High Power Impulse Magnetron Sputtering (HiPIMS). The present results provide an efficient and reliable approach to the improvement of smart material behavior.

TiAlSiN monolayer coatings with different hardness and hardness-modulated TiAlSiN multilayer coatings with varied modulation periods were obtained on WC-Co substrates by plasma immersion ion implantation and deposition using TiAlSi cathodes. (Ti, Al)N (111), (200), (220), (311) and (222) diffraction peaks could be found in X-ray diffraction (XRD) patterns of the as-deposited coatings and a preferred orientation (Ti, Al)N (200) peak was obvious for all samples. Energy dispersive X-ray spectrometry (EDS) results showed that the TiAlSiN monolayer coating prepared at a high N-2 pressure obtained a large Si content. The nano-indentation tests revealed that the hardness of the TiAlSiN monolayer coating could be varied from 33.71 to 41.43 GPa when the N-2 pressure during the deposition process was changed from 0.08 to 0.2 Pa, which proved that hardness-modulated TiAlSiN multilayers could be obtained by varying the working pressure. Meanwhile, the hardness (32.25-37.56 GPa) of the modulated multilayers lied between those of the TiAlSiN monolayers. Scratch tests exhibited that the TiAlSiN monolayer coating prepared at 0.2 Pa N-2 pressure peeled obviously at the L-C1 value of 20.8 N, while that of the multilayer coating occurred at 144.4 N. Tribological tests showed that the wear rate of the hardness-modulated TiAlSiN multilayer coating could be reduced to 1/8 of that of the monolayer coating.

Machine condition monitoring is important for health management of mechanical systems, efficient feature selection technique will promote the model performance for the monitoring. This paper proposed a new method for condition health monitoring based on an improved variational mode decomposition (VMD) and granular computing method. The singular entropy increment (SEI) was used to optimize the mode decomposition number of intrinsic mode functions (IMF) for the VMD method, then the granular computing method was employed to select the optimal feature subset from a high dimensional dataset. The developed method was used to assess the health status of a continuous cutting process, and the method was also compared with the empirical mode decomposition (EMD) for cutting tool health monitoring. The experimental results demonstrated that the proposed method can achieve a high classification accuracy with the optimal feature set, which indicates that the method is promising in the application of tool wear condition monitoring for mechanical systems.

螺纹连接是侵彻弹体与引信体连接的主要形式之一,针对现有动力学数值分析手段无法准确表征螺纹连接问题,提出利用薄层单元模拟螺纹连接的解决方案,并建立基于试验结果对薄层单元材料参数识别的方法.开展管螺纹模态试验研究,分析激励力幅值与螺纹松、紧连接状态对模态频率与频率响应曲线的影响,将薄层单元方法应用于管螺纹仿真计算中.结果 表明:螺纹松连接状态相比紧连接状态受非线性因素的影响更大;激励力大小对螺纹松连接的测量结果影响更大;与节点固连建模方式进行比较,采用薄层单元仿真计算之后,模态频率最大误差从26.66％下降到1.35％.

To develop a fast and economical process of preparing NiAl coatings on steel substrates, the plane wave propagating mode of combustion synthesis was employed in this study. Prior to the combustion process, Ni/Al compacts were obtained with a pressure of 180 MPa. To improve the adhesion strength of the NiAl coating, a Cu-Zn foil, which could be melted by the heat in the combustion synthesis process and acted as a joining layer, was mounted between the Ni/Al compact and the Q235 substrate. The combustion reaction of the Ni/Al compact was triggered by an arc, and propagated along the substrate surface. The phase composition and microstructure of the as-synthesized NiAl coating and the joining area were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy. The XRD results showed that the coating was composed of NiAl and some Ni2Al3 when the preheating temperature was lower than 300 degrees C. When the preheating temperature reached this value, only NiAl could be found. Additionally, in the joining area, CU0.64Zn0.36, NiAl, Ni3Al as well as unreacted Ni could be characterized. The influences of the applied pressure and the preheating temperature on the adhesion strength of the as-synthesized coating were also investigated. When the applied pressure was enhanced from 10 to 40 MPa, the shear strength between the NiAl coating and the substrate was increased from 52.3 to 60.8 MPa. However, when the preheating temperature rose from 0 to 300 degrees C, the shear strength increased firstly and then decreased with it. When the preheating temperature was 100 degrees C, the shear strength reached the maximum value, 64.7 MPa.

A finite element model with a heat source based on a temperature criterion was used to simulate the combustion synthesis process of the NiAl coating, and the influences of the processing parameters on the distributions of the temperature were analyzed. In addition, the surface and inner temperatures of the reaction system were tested by a thermal infraraed imager and a thermocouple, respectively. The simulated and experimental results of surface temperature distributions of the NiAl compact in the self propagating process are similar, indicating that the finite element model can accurately simulate the temperature changes of the self propagating process. The surface temperature of the substrate reaches the maximum temperature with the propagating of combustion wave. The highest surface temperature at different locations of the matrix are different, distributed wavily, lying at 913.4-1 044.0 degrees C. The temperature of the Ni/Al compact and the substrate can be increased by a preheating. When preheating to 300 degrees C, the surface temperature of the substrate can reach 1 123.3 degrees C. When the Ni/Al reaction was ignited from the middle, the spead rate was the same as that ignited from the side, but the spead time was reduced by half, which caused the combustion more concentrated and the temperature of the compact and substrate higher.

高等教育正成为军民融合深度发展的关键主体.军民融合为高等教育提供了新的平台与技术转移阵地、新的创新生态系统和创新发展机遇;高等教育则为军民融合提供了关键的人才资源、科技生产力和创新动力保障.当前高等教育的军民融合参与应着力解决思想观念、顶层统筹统管体制、政策法规和运行机制、工作执行力度等4方面核心问题,不断提高军民融合参与的广度、深度、强度和厚度.

In order to extract the mapping relationship between the structure parameters and the damping coeffi -cients of micro-channel , three-layer feed-forward neural network was adopted to build the damping feature model . Meanwhile , to improve the training efficiency of the model , PSE-BP algorithm was proposed .The damping feature model was trained with the samples generated by numerical simulation by taking the straight rectangular micro -chan-nel as an example .The trained model are verified by experiments .Compared with BP algorithm , the training effi-ciency of PSE-BP algorithm is improved by more than twenty times .The trained results are in good agreement with the simulation results .The average deviation of the theoretical and experimental results trained by PSE-BP algo-rithm is 5.2％.The average deviation of the theoretical and experiment results trained by BP algorithm is 5.8％. The theoretical and experimental curves are in good agreement .

Due to the special performance requirements on the composite body structure,the shape and the material of the composite body are quite different from that of the common body,and the change of body quality parameters,such as the mass and the centroid position,has negative impact on the vehicle steering stability.Through taking the shape parameters β1,β2 and h of the composite body structure as the design variables,the nonlinear relationship between the steering stability,the body internal space and the quality of body with the design variables is established by using the dynamic modeling and the analysis of the vehicle and the response surface approximation method,and the design variables are optimized by using the target programming algorithm.The optimization results show that,compared with the preliminary design,the serpentine score of the condition of stability control by the method in this paper increases by 22% with the expense of the internal space part of the body,and the body mass decreases by 30 kg.

To reduce the surface roughness of the screw, orthogonal experiment of form grinding process parameters was carried out based on orthogonal design theory.Considering the complex and asymmetric characteristics of screw rotor surface, a formula for the evaluation of the surface roughness of screw rotor was proposed.Furthermore, based on the experimental results, grinding process parameters were optimized and the relationship between grinding parameters and surface roughness of screw rotor was established by using multivariate nonlinear regression method.The results show that the optimized parameters could decrease the surface roughness of the female rotor and the male one by 1.6% and 2.4% respectively, and the reliability of this formula was verified by comparison experiment.All of which are helpful for the process of mass-form grinding screw rotor.

In order to study electron trajectories in an annular cathode high current pulsed electron beam (HCPEB) source based on carbon fiber bunches, the transmission process of electrons emitted from the annular cathode was simulated using a particle-in-cell model with Monte Carlo collisions (PIC-MCC). The simulation results show that the intense flow of the electrons emitted from the annular cathode are expanded during the transmission process, and the uniformity of the electron distribution is improved in the transportation process. The irradiation current decreases with the irradiation distance and the pressure, and increases with the negative voltage. In addition, when the irradiation distance and the cathode voltage are larger than 40 trim and -15 kV, respectively, a uniform irradiation current distribution along the circumference of the anode can be obtained. The simulation results show that good irradiation uniformity of circular components can be achieved by this annular cathode HCPEB source. (C) 2016 Elsevier B.V. All rights reserved.

To achieve intellectualization and miniaturization of fuze,a novel high-g dual-threshold MEMS (Micro-Electro-Mechanical Systems)inertial switch has been designed and simulated under the premise of ensu-ring its service safety and launching reliability.The MEMS inertial switch consists of two modules named rec-ognition module M1 and energized module M2 respectively.It can recognize two typical loads (load 1∶15 000g-300 μs,load 2∶3000g-3 ms)by taking advantage of collisions between a mass and two baffles without power consumption.The planar Z-shaped tooth on the mass and two baffles are significant to recognize these two dif-ferent loads and their parameters have been studied.Dynamic simulations have been taken to optimize the de-sign.Corresponding simulation results show that when load 1 is applied on the switch in the sensing direction, it keeps disconnected.While load 2 is applied in the same direction,it is closed.

In order to irradiate circular components with high current pulsed electron beam (HCPEB), an annular cathode based on carbon fiber bunches was designed and fabricated. Using an acceleration voltage of 25 kV, the maximum pulsed irradiation current and energy of this annular cathode can reach 7.9 kA and 300 J, respectively. The irradiation current density distribution of the annular cathode HCPEB source measured along the circumferential direction shows that the annular cathode has good emission uniformity. In addition, four 9310 steel substrates fixed uniformly along the circumferential direction of a metal ring substrate were irradiated by this annular cathode HCPEB source. The surface and cross-section morphologies of the irradiated samples were characterized by scanning electron microscopy (SEM). SEM images of the surface reveal that crater and surface undulation have been formed, which hints that the irradiation energy of the HCPEB process is large enough for surface modification of 9310 steel. Meanwhile, SEM cross-section images exhibit that remelted layers with a thickness of about 5.4 mu m have been obtained in all samples, which proves that a good practical irradiation uniformity can be achieved by this annular cathode HCPEB source. (C) 2016 Elsevier B.V. All rights reserved.

For the common parametric uncertainties and uncertain nonlinearities(hysteresis,nonG linear friction,external disturbances,et al)existing in electro?hydraulic servo systems,a novel methG od was proposed,which was based on adaptive robust control,and named prescribed performance tracking control with hysteresis compensation.First,taking valve controller single?rod hydraulic cylG inder position servo system for instance,a mathematic model consisting of hysteresis nonlinearity was constructed.And then,a prescribed performance function was utilized to characterize the convergence rate,maximum over?shoot,and steady?state errors.At last,an adaptive robust controller was design based on the planned tracking errors to guarantee the excellent steady?state performance and transient performance.Extensive simulations show that the proposed controller can attenuate the hysteresis effects on the tracking accuracy,improve the convergence rate,reduce the over?shoot,and eventually achieve an excellent tracking.

为快速预测微尺度下液柱受惯性力作用时其分界面的运动位移,基于非定常伯努利方程建立了其理论模型.首先,推导了惯性力作用下微液柱的运动方程.然后,利用封闭的环形微通道仿真模型,对微液柱受阶跃型加速度作用时的动态响应进行了数值仿真,利用仿真数据拟合得到了对应的待定系数k值,并进一步确定了k值表达式.最后,制作了微通道实验样机,利用高速摄影机和离心实验平台进行离心加载实验.结果表明,所建立的惯性力驱动微液柱运动模型,可用于预测微尺度下液柱的分界面运动位移,其计算精度满足工程设计要求.