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Numerical simulation and prediction of grain formation and defects, including the stray grain and high angle orientation deviation during directional solidification process of a single crystal superalloy hollow turbine blade are experimentally conducted by means of commercial software ProCAST and backscattering scanning electron microscope. The results show that the initial nucleation amount at the beginning section of the starter block is 104 of magnitude, and the number of grains decreases gradually with the competitive growth, and the number is about 100 at the spiral of the selector. And the orientation distribution of grains is close to direction, with the orientation deviation between 10° and 15°. Moreover, with the increase of withdrawal rate, the curvature of isoline of liquidus of single crystal blade increases, and the tendency to form stray grains defects increases. The grain with a large deviation from orientation blocks the growth of other grains at the first rotating transition site of the selector, and then gradually grows and solidifies to form the final blade.

In this paper, thermoelastic damping (TED) in a simply supported rectangular functionally graded material (FGM) micro plate with continuous variation of the material properties along the thickness direction is performed. The equations of motion and the heat conduction equation coupled with the thermal effects are derived based on the Mindlin plate theory and the one-way coupled heat conduction theory, respectively. The heat conduction equation with variable coefficients is solved by using the layer-wise homogenization approach. Analytical solution of TED is obtained by complex frequency method. Numerical results of TED are presented for the rectangular FGM micro plate made of ceramic-metal constituents with the power-law gradient profile. The effects of the shear deformation, the material gradient index, the plate thickness on the TED of the FGM micro plate are studied.

Corrosion leakage became serious due to cyclic sewage injection and continuous increase in water injection pressure. Corrosion behavior for N80 casing was studied during long-term service, using corrosion reaction kettle and weight loss method. The morphology and composition were characterized with laser confocal microscopy (LCM), scan electron microscopy (SEM) and energy disperse spectroscopy (EDS). These results showed that corrosion rate remained constantly at initial stage, and increased gradually, then sharply reached to 0.327mm/a at later stage, accompanying with inflection point under oxygen condition. Meanwhile, corrosion rate decreased significantly from 0.028mm/a to 0.020mm/a under oxygen-free condition. The corrosion of N80 steel was dominated by dissolved oxygen, and accelerated by chloridion. The micro-mechanism was suggested to be the transition of defect structure from crack with micron range to etch pit with millimeter range.

Azapropellanes have been extensively studied for their special application. Debenzylation of pentabenzylpentaaza[3,3,3]propellane was studied in this paper. The N-benzyl groups were removed by catalytic hydrogen transfer under the mild conditions with simple process. The yield of the debenzylation product was lower. Their structures of all compounds were confirmed by spectra.

In view of the external thread fracture during casing running in a well in Xinjiang Oilfield, the failure reasons of thread fracture were analyzed by combining the theory with experiment, and the casing safe service window with harsh working conditions was given. The operation of the failed casing and determined the actual working conditions of the casing threaded joints during the running process were investigated in this paper. According to the theoretical method, the boundary conditions and load conditions of the fracture casing joint in service were determined. With the aid of full-scale physical simulation test device, as well as the above boundary conditions and load conditions, the same batch casing tensile bearing characteristics were determined. Through nondestructive testing, the metallographic observation, scanning electron microscopy, spectral analysis and up-and-down test, the main controlling factors of casing thread fracture were determined. By the finite element analysis, the casing threads service state under axial tension and bending loads was established, the safety performance of threads under ideal working conditions was studied, and the fatigue mechanism of threads was revealed. Combined with the analysis results, the corresponding relationship between the casing tensile bearing characteristics and safety factor was given, which provides technical support for the safe service selection of casing body and thread under harsh conditions, saving cost and shortening the well construction period.

To introduce a method for reliability analysis of China's large-scale natural gas pipeline system, one should first have a method to calculate the reliability of pipe segments, compressors, valves, and other factors. This article models the rules prescribed in BS7910-2013, a guide to methods for assessing the acceptability of flaws in metallic structures, and combines pipeline reliability assessments from CSA Z662-2015 to present a method (based on the Monte Carlo method) to calculate the failure probability/reliability of long-distance pipelines containing a large number of girth weld defects. The method involves the destruction of plastic material, brittle fracture failure analysis, consideration of the division of units by using pipeline area classes for calculation, and reliability index analysis. The results of a magnetic flux leakage (MFL) in-line inspection (ILI) of a defective girth weld from a section of a pipeline in China are used to demonstrate how to determine the reliability of the entire pipeline.

The quasi-regular arrangements porous silicon was fabricated by by electrochemical process using organic solutions with front-side illumination, and SEM showed that the morphology of porous silicon was dependent sensitively on the current density, organic electrolytes and their concentration. The results indicate that N-dimethylformamide (DMF) is the best organic solution and quasi-regular arranged pores can be well organized in 20%HF/DMF solution. The luminescence shows fresh porous silicon can emit the red luminescence at room temperature and quench after nanoporous layer destroyed.

The second generation single crystal superalloy DD6 after standard heat treatment was respectively overheated at 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, 1320°C for 1h and air cooled. The effect of overheating on the microstructure and stress rupture properties at 980°C/250MPa of the alloy was investigated. The results showed that the size of γ′ phase was slightly increased overheating at 1100°C, 1150°C and 1200°C. The size of γ′ phase had a big increase and its size distribution was very uneven after overheating at 1250°C. The small part of γ′ phase has serrated γ′/γ phase surface as a result of un-completely solution and the irregular small γ′ phase was in the majority when overheated at 1300°C. While all the irregular small γ′ phase precipitated again after completely solution when overheated at 1320°C. There was no fine second γ′ phase in the γ matrix channel of the alloy after standard heat treatment and overheating at 1320°C. But the fine second γ′ phase precipitated in the γ matrix channel after overheating at every temperature of 1100 °C~1300°C. No obvious change of the stress rupture life was found after overheating at 1100°C, 1150°C, 1200°C and 1250°C. The stress rupture life considerably reduced after overheating at 1300°C, whereas slightly reduced after overheating at 1320°C. The appearance of the raft had almost no change after overheating at 1100°C. With increasing of overheating temperature from 1100°C to 1250°C, the length of raft became shorter and the width thickening. The γ phase formed the wavy raft after overheating at 1300°C and 1320°C and the thickness of latter was larger than that of the former. Finally, the relationship between the microstructural evolution and stress rupture properties of the alloy after overheating was discussed.

The microstructures of low angle boundaries (LABs) of a third generation single crystal superalloy DD9 in as-cast state and after different heat treatment processes were studied by optical microscopy (OM) and field emission scanning electron microscopy (FESEM). The results showed that the as-cast LABs of DD9 alloy consisted of rod-like and bulk γ' phases with γ matrix between them, and there were eutectic γ-γ' precipitating at the LABs, as well as small amounts of discrete distribution of carbides. The γ' phase locateed at the grain boundaries was larger than that distributed on both sides of the grain boundaries. After the solution heat treatment, as-cast eutectic γ-γ' at LABs dissolved completely, and rod-like γ' phase was still found at some LABs. Meanwhile, the LABs were inclined to be straight compared to the as-cast state. The primary aging heat treatment made γ' phase at the LABs dissolved completely, and the secondary aging heat treatment resulted little change in the morphology of the LABs. Thus, the effect of the primary aging heat treatment on the microstructures of the LABs was greater than that of the secondary aging heat treatment.

To theoretically evaluate three widely used second generation single crystal superalloys-PWA1484, ReneN5 and DD6, the alloy densities, phase graphs, TCP contents, d-electron energy, and creep rupture lives were calculated, and the calculation results were analyzed combined with actual data. Results showed that among the three alloys, PWA1484 had the greatest density, secondly was DD6, and ReneN5’s density was the lowest. The PWA1484 alloy was most likely to precipitate TCP due to its highest d-orbital energy level; the ReneN5 alloy had a medium d-orbital energy level, but its high Cr content induced it to precipitate the most TCP types; the DD6 alloy had the least chance to precipitate TCP phases because of its lowest d-orbital energy level as well as lowest Cr content. It is concluded that thermodynamic calculation had the ability to simulate TCP types and TCP content at steady states, while d-orbital energy concept was capable of exhibiting the alloys in sequence of TCP precipitation potential. Mere thermodynamic calculation will lead to comparatively conservative results, including more TCP types, higher TCP contents and lower rupture lives. Analyzing the thermodynamic and d-orbital energy calculations comprehensively, it can be considered that the DD6 alloy has the most stable microstructure among the three single crystal superalloys.

The precipitation behavior of γ′ precipitates in typical section dimensions of DD6 single crystal superalloy turbine blade was investigated experimentally during directional solidification process. The phase transformation temperatures in the single crystal Ni-based DD6 superalloy from DSC analysis and JmatPro simulation were basically in consistent with the isothermal solidification experiments. The solidification route of DD6 single crystal superalloy could be described as follows: L1 → γ + L2; L2 → (γ + γ′)eutectic + MC; γ → γ′/γ. With increasing continuous cooling rates, the primary γ′ precipitates tended to be refined, and the size distributions of the primary γ′ precipitates at every temperature measuring position followed the normal distribution. In comparison to the interdendritic regions, nearly a 60% reduction in the average sizes of the primary γ′ precipitates was measured in the dendritic core regions. The result of the primary γ′ size difference was strongly affected by the multi-component segregations between the interdendritic and dendritic regions, where the γ′ forming elements of Al and Ta segregated towards the interdendritic regions. Furthermore, the secondary γ′ precipitation was found to occur within a relatively wide corridor of γ matrix for low cooling rates (12.6, 23.3 and 29.7 °C/min) during the directional solidification process. The occurrence of the secondary γ′ precipitation resulted from the complex interaction of multiple thermodynamic and kinetic factors in the γ′ nucleation and the diffusion rate of γ′ forming elements.

The microstructures, phase constitutions and mechanical properties of as-cast samples, extruded rods and plates of Mg-3.52Sn-3.32Al and Mg-6.54Sn-4.78Al alloys were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction and mechanical testing. The results show that as-cast microstructure consists of α-Mg matrix, Mg2Sn and a few dispersed β-Mg17Al12 phases. The two as-cast alloys exhibit good tensile mechanical properties. After hot extrusion, dynamic recrystallization occurs. Average grain size reaches 6 μm ~ 8 μm for rods, and a lot of fine micro-scaled particles exist, resulting in significant enhancement of tensile mechanical properties. The extruded Mg-3.52Sn-3.32Al rod exhibits better comprehensive tensile mechanical property than AZ31B alloy, with tensile strength σb of 295 MPa, yield strength of 200 MPa and elongation of 21.5% at ambient temperature. The extruded Mg-6.54Sn-4.78Al rod exhibits equivalent comprehensive tensile mechanical properties with ZK60 alloy, achieving tensile strength of 355 MPa, yield strength of 275 MPa and elongation of 11% at ambient temperature. The extruded plates at ambient temperature performed a tensile strength of 270 MPa.

Experimental research was conducted using concrete produced by adding the polycarboxylic-type water-reducing agent. The cement, sand, aggregates, fillers and water-reducing agent were used as the important raw materials for the concrete. Then the following properties of the concrete were analyzed: compressive strength, elastic modulus and frost resistance. The compressive strength was 84 MPa at 56 days and the modulus of elasticity was 45.3 GPa at 28 days. Therefore, the water-reducing agent played an important role for the concrete. All the properties met the technical requirements of the CRTS III track plate.

Compared with the traditional water reducer, polycarboxylicwater-reducing agent exhibits the advantages of high water-reducing rate, cement paste fluidity and low slump loss, etc. The structure of polycarboxylates water reducing agent molecular is comb type. Water reducing agent can be used in the molecular design because it has high water reducing rate, low dosage, good slump stability, and have great potential in increase strength. In recent years, it has attracted many researchers' attention. Water reducing agent can block or destroy cement granular flocculation structure, through the surface function, complexation, electrostatic repulsion force and stereo repulsive force. Research on water reducing agent based on the application of poly carboxylic acid can realize functional design of water reducing agent, so as to promote the development of high-performance concrete.

A new process so-called air-cooled stirring rod (ACSR) was developed to prepare semisolid slurries of Al-8Si alloy. A simplified rheological high pressure die-casting (Rheo-HPDC) process was developed by combining the ACSR device with a HPDC machine to form wireless base station shells. Microstructures of slurries at different rotation speeds and air flows prepared by ACSR device were studied. Microstructures, mechanical properties and thermal conductivities of the shells formed by Rheo-HPDC were studied and compared with those produced by HPDC. The results indicate the ACSR device can prepare slurries in which primary particles are fine, spherical and uniformly distributed in the matrix. As rotation speed or air flow increases, the size of primary particles (α1-Al) decreases and shape factor increases. Rheo-HPDC parts show improved properties to those formed by HPDC, and increasing rates of ultimate tensile strength, yield strength, elongation, hardness and thermal conductivity are 15.4%, 8.2%, 62.1%, 6.67% and 2.1%, respectively.

The porous silicon carbide ceramics were fabricated by adding a variety of low melting point oxides in this paper. The additives were mullite, magnesium oxide, calcium oxide, and vanadium oxide. Effects of the additives content on the properties of porous silicon carbide ceramics were studied. The results showed that, when the additives content was greater than 2.8%, the apparent porosity, the bending strength, the permeability and the pore size were in an inversely proportional relationship with the additives content, while the content was less than 2.8%, proportional relationship was observed. When the additives content reached 2.8%, the porous SiC ceramics showed the best performances.

An arc spray gun with inner holes was used to spray two typical iron-based wear-resistant coatings, 08A and 08CrMoVA, on the inner wall of an aluminum cylinder block for an engine. In addition, microstructures of the coatings were observed through an optical microscope and a scanning electron microscope. Then, X-ray diffraction (XRD) patterns were employed to analyze the types of oxides in the coatings, and a quantitative metallographic analyzer was applied to test the porosity and the amount of oxides in the coatings. Afterwards, the coatings were immersed in the oil to conduct the wearing test and the test result showed that the coatings had better wear resistance, compared with the gray cast iron. Besides, it was further found that the coatings were formed on the substrate surface by the accumulation of flat particles, and unmelted particles, oxides, pores and fissures were also found in the coating layer. While being lubricated by oil, FeO in the coatings and the oil stored in pores decreased the friction coefficient and thus increased the wear resistance of the coating layer.

This paper discusses a digital control method for efficiency improvement of switching power circuit at light load by using C2000 Series DSP (Texas Instruments Inc.). In this work, we alter the module in DSP to adjust the link voltage between a bridgeless PFC AC/DC converter and a phase shift full bridge DC/DC converter, as well as to control the PWM frequency of power circuit in order to improve the power efficiency in a suitable way. Our experiments result show that the efficiency of the power circuit at half or light load improves by adjusting the link voltage and/or PWM frequency

TRISO coated fuel particle is the most important component in HTR fuel, the silicon carbide (SiC) coating layer is regarded as the pressure vessel to contain the fission products. During reactor operation, the inner pressure resulting from fission products and pyrocarbon (PyC) thermal effect will contribute to the failure of TRISO-coated particles. The higher temperature will result in the increasing of inner pressure and PyC thermal expansion, which will then change the stress of SiC layer. Considering the effects of temperature on inner-pressure expansion and elastic strain into the pressure vessel failure model, thermal effects on the stress of TRISO-coated particles were studied with analytical solution. The results indicated that the effects of inner pressure on the particle stresses were increasingly highlighted at the late stage of irradiation. And the increasing temperature caused a slight effect on PyC elastic modulus while elastic strain is unaffected greatly, either. Therefore, CFP stresses remain unchanged basically.

In this paper, ZnO nanocrystalline photoanodes were treated by zinc acetate aqueous solution. The effect of surface chemical modification processing on the photovoltaic performance and electrochemical properties of ZnO nanocrystalline dye-sensitized solar cells (DSSCs) were studied systematically. The SEM results revealed that the surface of the ZnO photoanode films were rough and some aggregations were formed after the surface chemical modification processing. The number of aggregations increased with increasing processing time, and showed wide grain size distribution simultaneously, which effectively increased the light scattering and decreased the grain boundaries to suppress the electron recombination. Moreover, the surface of these photoanode films were filled with micropores, which was benefit to the infiltration of electrolyte solution. The short circuit current density increased from 7.20 mA•cm-2 to 8.61 mA • cm-2 when post-treatment 20 min, and the maximum energy conversion efficiency reached 3.61%, which enhanced 43% compared with that without post-treatment.

The hot-gas corrosion resistance of DD9 single crystal superalloy at 900°Cwas investigated in the present study. The composition and the morphology of corrosion layer were characterized by energy dispersive X-ray analysis spectroscope (EDS) and scanning electron microscopy (SEM). The results show that DD9 single crystal superalloy has excellent hot-gas corrosion resistance and basically obeys parabolic rate law during corrosion test for 100 h at 900 °C. The irregular and prismatic morphology of NiO tightly piles each other on the surface after 100 h corrosion test. The corrosion products possess three layers, outer layer is predominate NiO with a little of Al2O3, middle layer is mixed oxide, and inner layer is sulfide. It was found that flake shaped NiS phase formed in the sulfide layer.

The stress rupture properties, fracture behavior and microstructure evolution of the second generation single crystal superalloy DD6 at different conditions were investigated. The results show that the alloy has excellent stress rupture properties. The fracture mechanism of stress rupture of the alloy at 760°C/785MPa, 760°C/750MPa and 760°C/720MPa shows quasi-cleavage mode and the fracture mechanism at 980°C/250MPa, 1070°C/160MPa and 1100°C/140MPa shows dimple mode, while the fracture mechanism at 850°C/550MPa shows quasi-cleavage and dimple mixture mode. Only a little change in the morphology of γ′ phase occurred at 760°C/750MPa. The γ′ rafts form at temperature above 760°C and the thickness of rafts increases with increasing temperature. The dislocation shear mechanism including stacking fault formation is operative at lower temperature and high stress. The dislocation by-passing mechanism occurs to form networks at γ/γ′ interface under the condition of high temperature and lower stress.

Plastic deformation and recrystallization of a Ni-based single crystal superalloy were experimentally investigated. Compression and Brinell Indentation were utilized to cause plastic deformation, and thereafter some deformed samples received heat treatment. Surface topography around the indent confirms the anisotropic plasticity of single crystal superalloys. The influential distance below the indent is much larger than that on the indent surface. Microstructural observation by Electron Back-scatter Diffraction (EBSD) shows that it is easier for nucleation and grain boundary migration in the dendritic arms. In addition, the recovery has almost no effect on preventing recrystallization for deformed samples with small plastic strains (around 5%).

Due to their high melting temperatures, low densities and excellent high-temperature strengths, Nb-Si-Ti-based ultra high temperature alloys shows great potential for vane materials on the next generation of high thrust-weight ratio aero-engines. In the present paper, the Nb-Si-Ti ternary system was studied, the phase diagram of Nb-Si-Ti and the phase fraction calculated, and the curve of solidification process established. The calculated results provide primary guidance for developing Nb-Si-Ti-X ultrahigh temperature alloys. Moreover, it is very useful as a guide for alloy design and processing development.

This paper introduced a kind of micro/nanomotion platform. The platform mainly includes 12 flexible hinges, piezoelectric ceramic driver (PZT), motion platform (loaded platform), pre-tightening force adjusting screw and so on. The orthogonal experiment method was used to the output displacement of the micro/nanoplatform. The relationship among the voltage, pre-tightening force and output displacement of the platform was analyzed. The factor level table of the output displacement was produced. The experimental system was established by Laser interferometer and pressure sensor, then the output displacement was obtained when the voltage ranges from 0V to 150V on the condition of every force (20N, 40N, 60N, 80N and 100N). The experimental result lays the foundation for the regression analysis of the output displacement of the platform.

This paper proposes a single inductor dual output (SIDO) DC-DC converter with an exclusive control circuit. We propose two kinds of converter: a buck-buck and a boost-boost converter. Multiple voltage outputs are controlled exclusively, using error voltage feedback. This approach requires a few additional components (a switch, a diode and a comparator), but requires no current sensors and does not depend on the value of output voltage or output current. We describe circuit topologies, operation principles and simulation results.

This paper describes digital auto-tuning schemes for second-order Gm-C bandpass filters which are suitable for fine CMOS implementation. We propose a switched Gm-C analog filter and two digital tuning schemes: a center frequency tuning scheme using the phase information and a Q factor tuning scheme using the magnitude information. We present circuits, describe their operations, and present SPICE simulation results.

The single crystal superalloy with [001] orientation were prepared by screw selecting method in the directionally solidified furnace. Three different cooling method, water cooling (WC), air cooling (AC) and furnace cooling (FC) were used after same solution treatment. Then these specimens received same two-step aging treatment. Influence of solution cooling method on the microstructure and stress rupture properties of the alloy under the test condition of 980 °C and 300 MPa was investigated. The microstructures of the samples were examined by scanning electron microscope (SEM). The results showed that the solution cooling method of heat treatment played an important role in the microstructure and stress rupture properties of the alloy. The size of γ′ phase and the width of the γ matrix channel of the alloy increased with decreasing cooling rate. The stress rupture properties of the alloy increased at first and decreased afterwards with decreasing cooling rate. The alloy with air cooling (AC) has the best stress rupture properties. The γ′ phase changed into a perfect raft structure during the stress rupture process of the specimens with AC method. However, the γ′ phase changed into a very irregular raft microstructure in the specimens with the water cooling (WC) and furnace cooling (FC) method. The micro-cracks in the specimen with irregular raft make the initiation and interconnection easier than that in the specimen with regular raft. Therefore, the alloy with AC method has optimum microstructure and stress rupture property.

The microstructure and mechanical properties of the high-purity magnesium (99.99wt.% Mg) extruded by single direct extrusion experiment were investigated. For the extrusion speed of 0.2mm/s, the microstructure of extruded Mg rods was composed of equiaxed fine dynamical recrystallized (DRXed) grains and some elongated coarse un-DRXed grains. The yield strength (YS) and the elongation of the extruded bars were 105.3MPa and 46.7% respectively. In the case of extrusion speed of 4.0mm/s, the DRXed grains were remarkably coarsened and the elongated coarse un-DRXed grains vanished, meanwhile lots of twins occurred and the intensity of basal-plane texture increased a little. With the extrusion speed being raised from 0.2mm/s to 4.0mm/s, the YS and the elongation decreased to 60.5MPa and 22.1% respectively, but the ultimate tensile strength (UTS) was improved from 154.7MPa to 178.8MPa.

According to the basic principles of electromagnetism, the magnetic flux density on the surface of the metal melt was calculated by numerical simulation method. The relational expression of the electromagnetic body force and the magnetic flux density was deduced. The results show that the electromagnetic body force in the melt is directly proportional to the square of the magnetic induction intensity. Increasing the electric current, the electromagnetic body force in the melt can be increased effectively. Increasing the frequency, the particular electromagnetic body force within the melt can be increased first and then decreased.

This paper proposes an improved L index which is adapted to analyze the voltage stability of power system with the ZIP loads. First it introduces derivation of the traditional L index. Then, it analyzes the differences between ZIP loads and PQ loads and then proposes an improved version of L index based on the derivation. Furthermore, the proposed improved index is used to analyze the voltage stability under different operation conditions of the power system with ZIP loads. The simulations show the effectiveness of the proposed improved L index.

(Sr1-xBax) 2(Nb0.9Ta0.1) 2O7 (SBNT) ceramics were prepared by solid state reaction. The crystal structure of SBNT ceramics, surface morphology and dielectric properties were studied using XRD, SEM and LCR instrument analyzer, respectively. The results show that the grain size decreases with increasing Ba concentration, and all samples show single phase, no second phase can been observed. Addition of Ba ion can improve the dielectric properties of SBN ceramics. The dielectric constant increases first, then decreases; the maximum value (εr=97) can be obtained at x=0.1, the dielectric constant changes slightly with increasing wide frequency.

In application-layer DoS/DDoS attacks, malicious users attack the victim server by sending lots of legitimate requesting packages, which overwhelm the server bottleneck resources. Normal user’s request thus may not be satisfied. The traditional intrusion detection systems for network-layer cannot effectively identify this attack, and recent researches on this kind of attack are mainly for Web servers. This paper proposed a new defense algorithm based on user activity for topic-based Pub/Sub communication servers in mobile push notification systems. Users consuming system bottleneck resources the most can get high scores and thus are considered overactive. With some resource retaken strategy, overactive users’ connections will be dropped according to system performance level. Therefore, the system can get rid of latent threatens. Experiments indicated that this algorithm can identify normal and abnormal users well.

The photovoltaic effect in Ag/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3heterostructures was investigated and the short circuit photocurrent was found to be strongly dependent on the polarization orientation and oxygen vacancies (VOs) distribution. The photocurrent direction was switched accompanying polarization switching. Besides, according to manipulate theVOsaccumulated at either the Ag/Bi0.9La0.1FeO3or the Bi0.9La0.1FeO3/La0.7Sr0.3MnO3interface by electric pulses, obvious enhancement of photovoltaic effects was obtained. These results can be explained well using the concepts of drift current and diffusion current controlled by the combination of oxygen vacancies and polarization. This work provides deep insights into the nature of photovoltaic effects in ferroelectric films, and will facilitate the advanced design devices combining spintronic, electronic, and optical functionalities.

Bismuth ferrite is an important material in ferroelectric photovoltaic field, because of its narrow band gap and large polarization. Doping is a common method to further improve the photovoltaic properties of bismuth ferrite. Mn-doped bismuth ferrite thin films were prepared by sol-gel method. The effects of manganese on the crystal structure, ferroelectric and photovoltaic properties have been investigated. The result indicates that Mn-doped bismuth ferrite thin films are single phase and the lattice constant increases with the increase of manganese content. As manganese content increases, the remnant polarization and coercive electric field increase, while the short circuit photocurrent density and power conversion efficiency decrease. The open circuit photovoltage increases first and reaches the maximum and then decreases as manganese content increases. The results indicate that enhanced ferroelectricity caused by addition of manganese doesn’t make improvement on the photovoltaic characteristic.

Based on the direct reduction alloying theory, the kinetics investigations on process of direct smelting and alloying between high-carbon ferrochrome and molybdenum were conducted. The results indicate that at the high temperature MoO3(g) can easily reduced by carbon dissolved in iron liquid. Reducing the volatilization loss of MoO3is the most effective measure to increase the Mo yield. With regard to the reaction between CaMoO4(l) and dissolved carbon at steelmaking temperature, the increases of mass transfer coefficient of CaMoO4in slag and phase contact area between metal and slag make for increasing the reduction rate. CO gas generated from extra carbon acting as reducing agent can provide favorable kinetics conditions for reduction reaction. The reaction between Cr7C3(l) and MoO3(l) in liquid steel is similar to the reaction between CaMoO4(l) and dissolved carbon. The incensement of mass transfer coefficient of MoO3(l) in slag can improve the reduction rate effectively. The CO gas generated from reaction can stir molten bath promote foam slag formation, so as to increase the phase contact area, which provides favorable kinetics condition.

In this paper, a new method using wavelet packet energy spectrum to identify transformer inrush and internal fault current was proposed. Wavelet packet transform respectively decomposed inrush and fault current, then calculated the energy of each frequency band of decomposed signal. Finally, the conclusion showed that the energy of internal fault in high frequency band is much less than that of inrush. The difference was quantified and it could be observed intuitively. Through extensive simulations, this paper proves that the method in terms of identifying transformer inrush is accurate and effective.

Slow strain rate test (SSRT) applied with different potential was adopted to investigate the stress corrosion cracking (SCC) sensibility of stainless steel under marine environment. The fracture morphology of 321 stainless steel SCC specimens were analyzed with the aid of SEM. The strain-stress results showed that 321 stainless steel exhibited less SCC sensitivity when anodic potential or cathodic potential were applied on the specimen, both fracture elongation and fracture time ascended compared with that of corrosion potential. The fractography analysis results also proved this susceptibility clearly.

This paper uses the L indexes to analyze the impact of large-scale wind power penetration on the static voltage stability of the power system. First it presents some common indexes in analyzing voltage stability. Then, it introduces the principle of the L index. After that, Simulation based on the L Index of a typical power system interconnected with large-scaled wind power shows the grid alternatives have a considerable impact on the voltage stability. Finally it gives the conclusions.

In this paper, we describe some privacy threats in the Internet of Things and some research works on privacy protection. We present a new scheme base on cryptosystem to protect privacy in the Internet of Things. The scheme includes location privacy protection, data privacy homomorphism mechanism and information hiding technology, and secure multi-party computation on data privacy.

The research of diagnosis and treatment system of child mental health disorders is based on artificial neural network and expert system. It combines the diagnosis standard of ICD 10, DSM IV with 40 years clinical experiences and knowledge of senior child psychiatrists. It also combines computer science with child psychiatry, child psychology, psychological estimate, psychological therapy and so on. The learning samples come from the epidemiological data in more than a dozen nationwide hospitals. The correct rate of system diagnosis is 99%. The system can diagnose 61 kinds of child mental health disorders and give a treatment method suggestion.

In order to study the impact of mechanical properties of aluminum alloy that is added into carbon powder, the aluminum alloy with carbon powder were melt and test bars were cast. The mechanical properties were tested by a tensile tester, the fracture morphology were observed by SEM and the morphology of material surface and composition were checked by SEM and EDAX. The results showed that: several slip platforms were observed during bar stretching and the longer slip platform is better elongation, so the ductile of alloy was improved obliviously after adding carbon powder. Microscopic studies showed that the aluminum alloy system has been infiltrated by the carbon powder and some stable compounds were formed in the alloy systems. Overall, Carbon is added can effectively promote the toughness of the aluminum alloy and improve the mechanical properties to some extent. Keywords: Carbon powder, Cast aluminum alloy, Slip platform, Toughness

The vehicular LNG(Liquefied Natural Gas) tank is a key component in the land transportation of-163°C LNG. The cryo-insulation performance of vehicular tank directly affects the security of LNG transport greatly. Based on a 40m3 vehicular LNG tank, a structural design of the vehicular LNG tank is completed, which includes its body,nozzles,heat-insulating layer,sealing devices,saddles and so on. With the safety requirements of less than 2% LNG evaporation rate, the leakage heat of LNG tank is analyzed completely. Then, a heat-insulating layer outside of LNG tank is completed with thermal design. Finally, with thermal software, the effectiveness of heat-insulating layer is proved.

The Internet of things is the technology extension and expansion of computer, Internet and mobile communication network. We will strongly rely on the Internet of Things in the future. The Internet of Things provides more conveniences, but it also will face more threats. In this article, we describe architecture of the Internet of Things, the function of every layer and what components every layer need. Our emphasis is to analyze the threats for the security and privacy at different levels of architecture in the Internet of Things.

Skin Stapler is an alternative instrument, which makes surgy easily and quickly and owns fine-looking effect without scars after the wound healed, to traditional surgical suture for the wound skin sewing. Magnesium recently is considered to develop medical implants because of its beneficial biocompatibility and bioabsorability. Due its less mechanical strength than traditional 316L stainless steel used in common staple, this paper try to optimize the structure of pure magnesium skin staple by FEM models and simulation as so to assure its biomechanical safty. Using ADINA software, two staples with different pre-bended shoulders and the traditional staple without shoulder are modeling to analyze its stress and plastical strain during structural deformation under load. The results, not only of pure magnesium models but also of 316L stainless steel models, showed that the shoulders optimization on staple structure has important role in its mechanical performance. The research increases the possibility of bioabsorable magnesium material application on medical skin staple.

The design uses silicon-AlN thin films as the piezoelectric substrate, Use apo- dization weighting methods to optimize the design of IDT. The improved δ function model was Modeling Tools of Apodization weighted ellipse IDT structure, According to the result of simulation, we designed a layout of SAW band-pass filter and fabricated a sample of it which center frequency is 300MHz and insertion loss is 7dB, The research shows the consistency of simulation results with the experimental results.

Using 663-tin bronze, Ni, W, nanoAl2O3, MoS2, graphite, CaF2, and Ni coated graphite as the matrix alloy powder, in which copper-coated carbon fiber of 5%, 7%, 9%, 11% and 13% in volume fraction were added as the reinforcing phase, a novel type carbon fiber/copper-matrix self-lubricating composite materials was prepared by means of powder metallurgy. The results indicate that the mechanical properties of the composite materials are improved after adding copper-coated carbon fibers. The composite materials reach optimal overall mechanical performance under testing when the volume fraction of the added copper-coated carbon fibers is 11%.: with a hardness of 57.8 HV and a compressive strength of 222 MPa. The addition of carbon fiber also improved the friction and wear properties of the composite materials. Increasing the volume fraction of fiber, was found to increase the wear resistance and improve self-lubricating performance. A volume fraction of 11% gave a friction coefficient of 0.09 and abrasion loss of 4mg.

Breakout is the most detrimental event associated with the continuous casting process, with the overview of the breakout prevention system, a lot of valuable things had been acquired. For breakout prevention, the embedded thermocouples had been proved best for breakout signals detecting. But in china, the system which used well in foreign countries did not fit for the current local condition, and gives error reports more often, so developing an efficient breakout system which fit for the condition of nowadays in China becomes more and more urgently.