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The concept and the primary preparation method of functional gradient materials are described in this paper. Functional gradient material is prepared as a tool electrode by electrochemical method and its performance is further tested in the micro electrical discharge machining (micro-EDM) experiments. Compared with the homogeneous material electrode, the functional gradient material electrode can effectively inhibit the wearing of the tool electrode and improve the distribution trend of current density during the micro-EDM process. The results disclose the prospects for functional gradient material to be used as tool electrode in the micro-EDM process.

The orientation effects of the organic functional groups CH3NH3+ along [100], [110], [111] and [210] on the stability and photoelectric properties of CH3NH3PbI3 were investigated using first-principles calculations. The results showed that the system energies when C-N bond was along [100]/[210] directions were lower than those while C-N bond was along [110]/[111] directions. The band gap while C-N bond was along [100]/[210] direction was larger than that while C-N bond was along [110]/111] direction. The system energy changed within the range of 0.8 eV, and the band gap changed within the range of 0.05 eV as CH3NH3+ moving along the same crystal direction. The optical properties of CH3NH3PbI3 with the C-N bond along [100] direction were different from those with the C-N bond along [111] direction, while the differences were not obvious. The change trends of optical properties with CH3NH3+ moving for two structures were in agreement with each other. The optical properties indicate that CH3NH3PbI3 is a good light absorber material for thin film solar cells.

Simulate rain experiment method was adopted to study the transformation of the change of raindrop speed and diameter with time and the results indicated that the rain intensity change strongly with time at the natural rainfall, However, the rain intensity was stability at simulate rainfall. At the natural rain, the raindrop speed mainly at 0.4-6.6m/s in different time, it have two wave crest were 1m/s and 3.4m/s. However, at the simulate rain, the raindrop speed mainly at 0.2-5.8m/s in different time; it has one wave crest was1m/s.In natural rain and simulate rain, the 0.125mm diameter raindrop speed were about at 0.4-2.6m/s and0.8-5.8m/s, the 0.25mm diameter raindrop speed was about at 0.6-2.6m/s and 0.6-5.8m/s, the 0.375mm diameter raindrop speed was about at 1-1.8m/s and0.4-2.2m/s, the 0.5mm diameter raindrop speed was about at 1-3.4m/s and 0.2-1.8m/s, the 0.75mm diameter raindrop speed was about at 3.4-4.2m/s and1-3.4m/s, the 1mm diameter raindrop speed was about at 3.4-4.2m/s and 1-3.4m/s, the 1.25mm diameter raindrop speed was about at4.2-5m/s and1-5m/s, the 1.5mm diameter raindrop speed was about at5m/s and 2.6m/s.

A kind of 10KV power distribution network fault indicator integrating measurement and communication functions was researched and developed. Used in 10KV power distribution overhead lines, this indicator is also designed with the communication module, current and temperature measurement module in addition to having the function of plate turning indication in case of grounding or short circuit fault. Through a wireless communication mode, the fault or measurement information is sent to the nearby data terminal unit, which sends the data to the monitoring center through the GPRS network. Workers will know the working status of the whole power distribution network in a real-time manner through the computer of the monitoring center. By adopting the ATmega8L MCU as the core, the new type of fault indicator realizes the wireless data transmission function through NRF24L01.

A kind of device for data storage is realized in this article. The data storage device (DSD) has USB and I2C port. By it we can transmit data from terminal for measure and control that base on SCM (single-chip microcomputer) to PC easily. DSD use EEPROM CMOS chip AT24C512 for storing data, and use USB chip CH341 for transmitting data to PC. This article showed AT24C512, CH341 and the characteristic of I2C BUS. The hardware for taking data and software for communicating between terminal and PC were designed in this article.

Operating characteristics of small and medium tonnage lattice boom crane which withstand fatigue loads was analyzed in this paper. It showed that the lattice boom crane utilization level is in the overlap zone of low cycle fatigue and high cycle fatigue. There may be some plastic deformation in the structure. So the total damage calculated by the Palmgren-Miner rule had a large scatter. Typical operating conditions was analyzed that K-type welded joints of the boom is under axial load and in-plane bending loads. Several critical areas of K-type welded joints were determined by ANSYS finite element calculation software where the stress amplitude was larger on the single side of the lattice boom. A new stress spectrum acquisition method based on the “measured+statistics+compare+simulation” integrated strategy of crane K-type welded joints was proposed. Based on a simplified Huffman non-linear cumulative damage theory, fatigue life of crane K-type welded Joints were calculated based on the strain parameters. They were compared with Palmgren-Miner rule and together with fracture mechanics method. Results showed that although they were all conservative compared with test results, the new method can be applied easily in for engineering applications because it only need amplitude constant amplitude fatigue strain-life data.

There are lots of distributed sources in the process of fatigue crack propagation of the lattice boom, static evaluation of the reliability indicators cannot be satisfied to solve practical engineering problems. The load and fatigue resistance regards as a random process, considers the fatigue failure of the randomness in a variety of factors, the concept of dynamic reliability of the weights index is proposed, models of dynamic reliability of the weights index are built based on the fatigue bearing capacity mode and limit damage degree mode. Fatigue stress experiments comparisons are doing during a crawler crane according to the actual operating conditions and a K-type welded joints prototype. The results show that the dynamic reliability evaluation assessment model is more accurately in the fatigue life evaluation and the method can provide a new assessment method for engineering applications.

The excessive tool wear always has a great influence on the machining accuracy in micro electrical discharge machining (micro EDM). According to the image processing on the image of tool electrodes, the contour information of the worn tools is obtained, and then the tool wear, especially the tool shape change in micro EDM is studied in this paper. Firstly, the Canny edge detection method is used to extract the outline image of the tool, the scatter points of outline image are curve fitted, and the mathematical description of the tool outline is presented. And then though the mathematical analysis of the fitting function, the tool shape change and tool wear law of micro EDM are analyzed. Finally, according to the curvature changes of fitting curves, the end wear, corner wear and side wear of cylindrical electrode in micro EDM drilling and micro EDM milling, respectively, are divided reasonably based on the analysis, and the amount of each kind of wear is quantitatively estimated.

To improve stiffness and strength of the deployable antenna truss and to keep the total weight and volume from increasing as caliber increases, this paper presents a new kind of deployable antenna truss with double-ring composed of hexahedrons. Numerical simulation was made by self-programming software and a scaled model of 4.2-meter diameter was designed and manufactured, which demonstrate the developability of double-ring deployable antenna truss. In addition, frequency analysis and experiment was taken to make sure of stiffness of the truss.

Aluminum substitution in CuInSe2could have important implications for photovoltaic applications. To better understand the Al doping effects, we have performed density functional calculations on the CuInSe2chalcopyrite as well as on Al-doped derivative compounds with different concentrations using the generalized gradient approximation. The structural and electronic properties of the pure and Al-doped CuInSe2have been calculated. We find that the substitution of In by Al creates structural deformation, and the band gap of CuIn1-xAlxSe2broadens as Al content increases. These are further discussed with the analysis of lattice parameters, bond lengths and angles, and electronic structures changes.

Based on density functional theory (DFT) within the framework of the generalized gradient approximation method, we have studied the Cd1-xZnxS sphalerite crystal structure and optical properties. We calculated electronic and optical properties of Cd1-xZnxS at the doping concentration x = 0, 0.25, 0.50, 0.75, 1.0. Optical properties (reflectivity, absorption coefficient, refractive index, dielectric function) and the electrical properties (band structure, electron density, etc.) are obtained including Zn-doing effects on the crystal structure, optical properties and electrical properties. With the increase of doping concentration x, the lattice parameter reduces from 0.5910 nm to 0.5409 nm; as a direct wide band gap semiconductor, its band gap increased from 1.15 to 2.22. Optical absorption coefficient increases with the increase of doping concentration, but the rate of increase is relatively small.

Through testing the errors of spur gear and helical gears, transmission error curve of non-grinding gear is drawn. The effect factors on gear transmission error are found. The transmission error effect factors of all kinds of gear high-low frequency are analyzed. It is obtained that gear kinematic error is the evaluating guideline of transmission precision. Experimental results shows that error of gear axial offset and gear frequency period have less effect on gear transmission kinematic error. While gear backlash and face width direction error have more obvious effect on kinematic error. The results provides reasonable theory basis for determining gear cutting precision.

In this paper, the advantages of smart materials and structures are introduced. Because of the influence of friction, it’s difficult to deploy the large ring truss antenna driving by cable. The SPMC hinge is added in the deployable joint, the deployable antenna is deployed by heating the material to cause recovery strain, which substitutes for the driving by cable. Describe the behavior of SPMC material, and do the simulation, from the analysis results, we can aim that the stress of SPMC satisfies the yielding stress when the node is furled. At the same time, the force to expand the antenna caused by heating SPMC is also obtained. Compared the different size of width, the variation of recovery force can be got.

We studied in detail the lattice transition and local lattice structure (including Jahn-Teller distortion) in LaMnO3/SrMnO3surperlattices by classical atomistic simulation. For a certain doping density, it is found that the superlattices with short modulation period have small lattice energies and larger differences among lattice parametersa,b/√2 andc. The average La-Mn (Mn3+-O) distance is larger than the average Sr-Mn (Mn4+-O) distance for all doping densities and superlattice configurations at certain doping density. The standard deviation of Mn-O bond lengths and Jahn-Teller distortion of MnO6octahedra have been calculated. Both the standard deviation and Jahn-Teller distortion of Mn3+O6octahedra in the superlattices are much smaller than those of Mn3+O6octahedra in LaMnO3, while Mn4+O6octahedra in the superlattices have the smallest lattice distortion, but larger than those in SrMnO3.

The fuzzy clustering algorithm is sensitive to the m value and the degree of membership. Because of the deficiencies of traditional FCM clustering algorithm, we made specific improvement. Through the calculation of the value of m, the amendments of degree of membership to the discussion of issues, effectively compensate for the deficiencies of the traditional algorithm and achieve a relatively good clustering effect. Finally, through the analysis of temperature observation data of the three northeastern province of china in 2000, the reasonableness of the method is verified.

Gemini surfactant flooding is a promising technique to enhance oil recovery from medium-high permeability oil reservoirs. The screening of the surfactants is mainly based on their capability of lowering the surface tension between oil and water. However, gemini surfactants with high capability of lowering the surface tension do not necessarily enhance oil recovery from low-permeability oil reservoirs. Based on the fractal analyses of low-permeability cores and molecular spacer group, the fluid mechanics of gemini surfactant flooding in low-permeability oil reservoir is discovered. The fractal dimensions of the spacer group of gemini surfactants should match the fractal dimensions of the pore structures of low-permeability oil reservoirs.

Lateral and edge wear of electrodes in micro-EDM affects workpiece shape accuracy. A method that change materials property of lateral side of electrode was put forward, based on discharge performance difference of different materials, and it was demonstrated with experiments. Results show that the method proposed is more effective and improves the precision of deep holes, compared with traditional sampling methods. The technology can provide reference to practicality of micro-EDM for 3D structure cavity and deep holes.

Wear course was experimental analyzed and mechanism of electrode wear was discussed based on finite element analysis and electromagnetic theory. Cu–TiN nano composite electrode was prepared on Cu electrode by electro deposition and effects of the electrode on discharging were studied. It is shown that electric field distortion and skin effect are two of the basic reasons on electrode wear. Cu–TiN nano composite electrode is one of the the effective ways for uniform wear of electrode in EDM.

In micro electrical discharge machining (micro-EDM) of deep holes, the debris dispersed in gap may increase the possibility of secondary discharge, resulting in electrode shape changing and low accuracy of machined hole. In this paper, the debris movement caused by flow fluid in the machining gap is analyzed to understand the mechanism of debris transport by using software, FLUENT. Comparison of debris movement calculated by the modified N-S equation and N-S equation is conducted. Debris movement calculated by the modified N-S equation is demonstrated to be correct by experiment. The simulation results can explain the phenomena such as subulate electrode and hole, unstable machining process and low machining speed in micro-EDM of deep holes. It is helpful to improve the process of micro-EDM.

In this paper, microstructure and mechanical properties of the chafer cuticle were investigated. The microstructures of the chafer cuticle were first observed with a SEM. It showed that the cuticle is a kind of chitin-fiber-reinforced biocomposite with protein matrix. There are some holes existing in the chafer cuticle and the fibers around hole are continuous. Based on the observed results of the SEM, the analyses of 3D models on the simple composite elements with fiber-round hole were conducted. The result showed the microstructures of composite laminates with fiber-round holes can decrease the stress concentration and well transfer the stress. So it can improve the strength and toughness of the composite laminates included holes. These conclusions may present a bio-inspired approach for design and development of advanced man-made fiber-reinforced composites.

Effects of additive powders on the machining mechanism of powder mixed EDM were researched. The whole discharging process was discussed based on theory of plasma and dielectric. Experiments, oscillograms and energy spectrum analysis gotten in experiments were performed in order to examine the changes of discharge between EDM and powder mixed EDM.

Grinding of single crystal silicon may be achieved by two modes of material removal: ductile mode and brittle mode. Knowing of the brittle to ductile transition point at which the grinding process changes from the brittle mode to ductile mode is critically important for the realization of ductile mode grinding. This paper uses a new single grain diamond grinding method developed recently by the authors to investigate the brittle to ductile transition during grinding of single crystal silicon in all around. The results indicate that there exist four stages of brittle to ductile transition as the depth of cut is reduced: firstly, the surface cracks outside the grinding groove disappeared, secondlycracks on the bottom of the groove disappeared, then the lateral cracks ceased in the subsurface region, and finally the median crack is suppressed beneath the grooves. It is not until the depth of cut reaches the last transition point that a crack-free groove can be produced, therefore, the last transition stage is decisive. The critical depth of cut delineating the brittle to ductile transition point derived based on this criterion is 40 nanometers, which is much lower than that based on surface cracks.

We have developed the laser nanoprocessing technique by the integration of the fs laser and near-field scanning microscopy (NSOM). The second harmonic femtosecond laser working in the optical near-field with the assistance of NSOM equipment was applied to expose the photosensitive polymer material. The nanopatterns with feature size smaller than the laser wavelength can be fabricated. The optical diffraction limitation is therefore broken through by the near-field nanoprocessing. It was found in our experiment that the nanofabrication feature size depends strongly on the gap between the fiber probe tip and the substrate surface, as well as the laser coupling efficiency. The approach offers the advantages of high precision, speed and selectivity in nanopatterning, and is promising to be used in data storage device manufacture for higher density recording.

A method for low resistivity resistor on transparent substrate with laser induced plasma assisted by ablation and laser annealing was described. The diffusion distribution for metallization was measured with XPS. The surface profile was analysed with SEM. The minimum resistivity we got was 0.1 /Sq. It demonstrates that the electronic thin film obtained has a very good conductivity. The most important factors for forming electrically conducting films on the transparent substrate are laser fluence, beam scanning and pulse repetition rate. This technology will be useful in the fabrication of LCD electrode, glass defused resistor and circuit on glass.

The dimensional accuracy of electro-discharge machining (EDM) is greatly influenced by the overcut resulting from discharge gap and electrode wear. In order to achieve fine accuracy, it is necessary to estimate the overcut according to an empirical formula. In this paper, experiments in electro-discharge machining were carried out. The effects of parameters on the overcut, such as peak current, pulse duration, were analyzed. Then an empirical formula for the overcut in EDM was established based on the experimental results using the least square method. Finally, reasonable agreement between calculated results and the further experimental results was obtained.

We successfully developed the potential parameters for simulation of MgB2. With these potential parameters, we calculate the lattice parameters and volume variations with pressure up to 240GPa. All these results agree well with experimental data under 40GPa and provide reasonable tendencies from 40GPa to 240GPa. By employing the McMillan expression, it is found that the lattice stiffening dominants the behavior of Tc under pressure in the scope of BCS theory. Using our calculated Grüneisen parameter G g , the simulated pressure effect on Tc accords well with experimental results. Our result shows that the Tc of MgB2 can be destroyed by high pressure.