Search

The self-diffusion in very thin Cu (001) film that formed by 2~11 atomic layers have been studied by using modified analytic embedded atom method (MAEAM) and a molecular dynamic (MD) simulation. The vacancy formation is the most easily in of Cu (001) thin film formed by any layers. The vacancy formation energy 0.5054eV in of the Cu (001) thin film formed by layers is the highest in all the values in the ones that formed by layers. The vacancy in and 3 is easily migrated to layer, and the vacancy in is easily migrated in intra-layer, and the vacancy in is easily migrated to when the corresponding atomic layer is existed. The vacancy formation and diffusion will not be affected by the atomic layer when the Cu (001) thin film is formed by more than ten layers ().

In this paper, multiphase composite Al2O3 ceramics including carbon nanotubes was fabricated by hot pressing sintering. And researching and analyzing the influence of different volume fraction of carbon nanotubes for the microstructure of multiphase composite Al2O3 ceramics by SEM.

In this paper, the noise of gear transmission system of the type, source and mechanism is summarized and analyzed. The method of noise control was put forward according to the mechanism of noise of gear system. Put forward reasonable Suggestions For gear type and material selection in the design of gear transmission system, the gear parameters, processing technology, cabinet design, gear train assembly, gear modification, the lubrication mode. For gear system optimization design has a certain guiding significance.

With the rapid development of computer technology and software technology, the application of linear canonical correlation analysis is more and more widely. But in practical applications, variables are often potential nonlinear relations. Therefore, it is necessary to study the nonlinear canonical correlation analysis algorithm, reveal the nonlinear relationship between variables of potential.

With the development of Chinese industry, stainless steel and wire rope pickling sludge pollution problems have become increasingly prominent. Pickling sludge contains a large number of residual acid and heavy metals, and it is hazardous waste which would pose potential environmental problems and threaten people's health if being deposited outdoors or landfill simply. In view of Jiangsu Province present situation of pickling sludge, the paper analyzes the physical properties and the elements content of sludge from 9 enterprises. Pickling sludge pH is basically alkaline and range 7 to 9, moisture content is basically about 50% to 60%. ICP-AES has been applied to identify the content of metals. The range of Fe content is from 13.23% to 35.56% and the range of Ca content is from 1.04% to 29.93%, which shows that pickling sludge is appropriated for resource utilization. Ni and Cr are mainly contained in pickling sludge of stainless steel, the content are 1.79%~3.2% and 2.22%~3.15%, while Pb and Zn are mainly contained in pickling sludge of wire rope, the content are 0.0034%~0.53% and 3.14%~10.18%. The Elemental Analyzer has been applied to determine the content of F, Cl, N, S and P in picking sludge. The paper aims to provide a theoretical basis for making the huge amounts of the sludge harmless and how to utilize the treated sludge.

The development status of self-lubricating tool materials was reviewed in the present study, as well as the five basic types of self-lubricating tool and the current situation of nanometer materials in ceramic cutting tool. Based on these, the design idea of the functional gradient materials and nano-micro composite materials was introduced into the self-lubricating ceramic cutting tool materials, in order to develop new self-lubricating ceramic cutting tool materials with both good mechanical and frictional properties.

No matter the bottom-up design mode is adopted or the top-down design is chosen, one-to-one dimension relation can be realized alone among assembly-components in three-dimensional CAD systems.In the paper, a method of automatic recognition is put forward based on assembly features in UG and various definitions as well as expressional methods of assembly features are analyzed. The interrelated dimension relation is established on account of the fit dimension chain. The converse parametric design is realized besides an independent module in UG is developed to achieve the function.

Unmanned Underwater Vehicle (UUV), which could be used for ocean exploration and development, developed rapidly in recent years. In order to make UUV quieter to be competent for rigorous working conditions, a new propulsion with lower underwater noise must be designed. A new high-skew ducted propeller, which had the advantages of both ducted propeller and high-skew propeller, had been designed for UUV to obtain adequate thrust and lower underwater noise. CFD simulation of the high-skew ducted propeller showed that the thrust was enough for UUV working underwater and the hydrodynamic efficiency was very close to that of conventional ducted propeller. The strength of high-skew ducted propeller had been checked by FEM method, and the maximum stress would appear on the trailing side of blade on 0.5R, where the blade was unsubstantial. Underwater noise had also been measured, which proved that the high-skew ducted propeller had lower noise than that of conventional ducted propellers. As a quiet propulsion, the high-skew ducted propeller could be used on UUV or ship who want to be quiet underwater.

A microgrid is an excellent supplement for both urban and rural utility grids. It assists in the integration of different kinds of renewable and distributed generation and it has the potential to make the distribution system more flexible and reliable. A microgrid is a combination of two or several energy resources like natural gas, wind, photovoltaic, biomass or diesel generators. Different energy resources together with battery storage system can complement one another to provide a more continuous power output. Two microgrid prototypes are discussed and, optional configurations are estimated using the economic analysis tool HOMER. Economic benefits and greenhouse-gas emissions of microgrids are calculated and compared. Results show that microgrids with optimal sizing and operation can achieve both cost efficiency and lower emissions.

The paper investigated the effect of chemical etching and temperature on the optical properties and microstructures of porous silicon layer fabricated by the pulse electrochemically etching by means of the reflectance spectroscopy and photoluminescence spectroscopy. The relationship between the optical thickness (nd) and refractive index n of porous silicon layer and the chemical etching time and temperature has been detailedly studied. With increasing the chemical etching times, the reflectance spectra exhibit the more intense interference oscillations, which mean the uniformity and interface smoothness of porous silicon layers become better, meanwhile, results in decreasing the optical thickness and refractive index, indicating a higher porosity. Moreover, the intensity of photoluminescence spectra increases, and the envelope curves of photoluminescence spectra exhibit a trend of red-shift, which implied the average diameter of silicon nanocrystallite became larger. The chemical etching rate of the optical thickness intensely increases with the chemical etching temperature.

Nanocrystallite Mg-3Al-Zn alloy was synthesized by ball milling of elemental powders of Mg, Al and Zn under hydrogen atmosphere. The powders of Mg, Al and Zn were mechanical alloying and disproportionated by ball milling under hydrogen and desorption-recombination was then performed. The structural changes due to both the milling in hydrogen and the subsequent desorption-recombination treatment were characterized by X-ray diffraction (XRD). The desorption–recombination behavior of the hydrogenation alloy was investigated by differential scanning calorimetry (DSC). The morphology and microstructure of the final alloy powders subject to desorption–recombination treatment were observed by TEM and HRTEM, respectively. The results showed that, by milling in hydrogen for 60 h, the Mg-3Al-Zn alloy was disproportionated into nano-structured with average size of about 60-70 nm, and a subsequent desorption–recombination treatment at 320°C for 30 min alloy didn’t vary the average crystallite size of powders.

The next generation of intelligent surveillance system should be able to recognize human’s spontaneous emotion state automatically. Compared to speaker recognition, sensor signals analyzing, fingerprint or iris recognition, etc, facial expression and body gesture processing are two mainly non-intrusive vision modalities, which provides potential action information for video surveillance. In our work, we care one kind of facial expression, i.e. anxiety and gesture motion only. Firstly facial expression and body gesture feature are extracted. Particle Swarm Optimization algorithm is used to select feature subset and parameters optimization. The selected features are trained or tested for cascaded Support Vector Machine to obtain a high-accuracy classifier.

The influence of bio-filter on domestic sewage treatment in purifying tank was studied in this paper. The result shows that when all the three zones were added bio-filter the mean values of effluent COD and NH3-N were 37.8mg/L and 9.64mg/L respectively, which shows that the bio-filter bed is a key technology and plays important roles for solid-liquid separation, bio-sorption and bio-degradation, to raise the effluent quality in the sewage treatment process.

The section of the column under axial compression used in a certain electrostatic precipitator is composed of double H shaped steel limbs and the stiffened connecting web by weld. As the width of connecting web usually exceeds 3 times of the section height of H shaped steel, the axis which connecting web lies in is the weaker axis for the stiffness of column section, while the midperpendicular of connecting web is the stronger axis. In consideration of initial geometrical imperfections and weld residual stresses, the study on stability round the stronger axis of column subjected to axial compression by nonlinear finite element method is conducted. The research results indicate that the column doesn’t present the flexural buckling round the stronger axis, but present the elasto-plastic flexural-torsional buckling. A buckling factor is produced to measure the stability performance of column round stronger axis. When the connecting channel shaped steels between two limbs and the stiffeners located on connecting web are strengthened, the buckling factor increases slightly. When the width-thickness ratio of connecting web increases, the buckling factor decreases significantly. When the slenderness of H shaped steel round the stronger axis is kept constant and the height-thickness ratio of H-shaped steel web increases, the buckling factor increases. Based on a great many computation results, the regressed recommendation is proposed how to evaluate the design buckling bearing capacity of column under axial compression round stronger axis.

In this paper, two ideal formation models of serrated chips, the symmetric formation model and the unilateral right-angle formation model, have been established for the first time. Based on the ideal models and related adiabatic shear theory of serrated chip formation, the theoretical relationship among average tooth pitch, average tooth height and chip thickness are obtained. Further, the theoretical relation of the passivation coefficient of chip’s sawtooth and the chip thickness compression ratio is deduced as well. The comparison between these theoretical prediction curves and experimental data shows good agreement, which well validates the robustness of the ideal chip formation models and the correctness of the theoretical deducing analysis. The proposed ideal models may have provided a simple but effective theoretical basis for succeeding research on serrated chip morphology. Finally, the influences of most principal cutting factors on serrated chip formation are discussed on the basis of a series of finite element simulation results for practical advices of controlling serrated chips in engineering application.

The fabrication is a key process for the preparation of ceramic tool materials, which governs the mechanical properties of ceramic tool materials under the condition of the same compositions. A computer simulation coupled with fabrication temperature for the hot-pressing process of single-phase ceramic tool materials has been developed using a two-dimensional hexagon lattice model mapped from the realistic microstructure without considering the presence of pores. The fabrication of single-phase Al2O3 is simulated. The mean grain size of simulated microstructure by Monte Carlo Potts model integrated with fabrication temperature increases with an increase in fabrication temperature, which is consistent with the experiment results.

A computer simulation of the sintering process of two-phase ceramic tool materials has been developed using a two-dimensional hexagon lattice model mapped from the realistic microstructure. The relationship between simulation time and real duration time has been proposed. The mean grain size of simulated microstructure increases with an increase in simulation time, which is consistent with the experimental results.

With the widely use of discrete problems in production scheduling, traffic control, logistics, management science and social science, the restraint of the integer solution to the discrete problem, adding to the difficulties. In this paper, knapsack problem as an example, the computational accuracy and computation in the next, studied the design and analysis of algorithms for solving discrete problems.