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The obtuse triangular defects would result in higher leakage currents and the preferential gate oxide breakdown of SiC devices. The formation and structural features of obtuse triangular defects on the 4° off 4H-SiC epilayers were investigated by confocal microscope and photoluminescence image. Two structrures of obtuse triangular defects were found. By optimizing the growth process, obtuse triangular defect free epitaxial layers were abtained on SiC substrate with serveral stacking fault. The number of triangular SFs defects was less than 0.5/cm2.

In this paper, the effects of hydrogen concentration on growth rate, micropipe density and nitrogen concentration of 4H-SiC crystals were discussed. It was shown that the growth rate is a linear function of the hydrogen concentration, which can be explained not only by C/Si ratio but also the temperature gradient. It was also found that the micropipe density was increased rapidly when the hydrogen concentration exceed a critical value, because the defects such as Si droplets, carbon inclusions and polytype formation were generated at that time. The results of secondary ion mass spectroscopy (SIMS) showed that with increasing the hydrogen concentration, the nitrogen concentration falls down but reaches a constant value which meets the requirements for high purity semi-insulating (HPSI) SiC single crystal growth. Finally, the HPSI 4H-SiC crystals were obtained using 15% hydrogen concentration, the resistivities of wafers cut from these crystals were more than 109Ω•cm, micropipe densities were less than 5cm-2, the full width at the half-maximum (FWHM) were between 30-40 arcsec, making these wafers suitable for microwave devices fabrication.

Dental ceramics has become dominant materials used in dental restorations. Dental ceramics have several advantages, such as stable performance, good bio-compatibility, little possibility to attach plaque, and similarity to the color of permanent tooth. However complex surface characteristics and hard and brittle properties of dental ceramic materials caused difficulties in the processing and subsequent grinding. The complicated craft and high failure rate of dental ceramics greatly limit its wide application in clinical. Thus, fully understanding the special cutting tools grinding performance and researching the material damage process caused by grinding temperature and grinding force are of great significance. Research on dental ceramic grinding was reviewed in this paper. The removal mechanism of dental ceramic materials and the influence of parameters settings on the grinding force, grinding temperature, and the surface quality have been studied. Besides the existing problems in dental ceramic grinding technology were pointed out.

The dry bias of MEMS humidity sensor induced by solar radiation heating seriously affects the accuracy of the relative humidity (RH) measurement. To solve this problem, this paper presents a novel numerical analysis method for the error correction of RH based on computational fluid dynamics (CFD). Firstly, considering the solar radiation, the distribution of temperature field of MEMS humidity sensor is simulated from the ground to 32km altitude by using CFD soft under the boundary condition of fluid-solid coupled heat transfer. Secondly, the numerical analysis model of RH is put forward for solar radiation dry bias (SRDB) correction based on the working principle of the MEMS capacitive humidity sensor and the definition of RH. The results of numerical analysis show that the error of RH caused by solar radiation is nonlinearly increased with the altitude. Meanwhile the errors decrease with the reflectivity of sensor or of solder point increase. The simulation data also indicate that the SRDB can be reduced by improving the reflectivity of sensor or of solder point, adopting the substrate material with high thermal conductivity or choosing the suitable thickness of sensor. However, the SRDB should be corrected, for it still is more than 20% under the low atmospheric pressure. In this paper, the method based on fluid dynamics simulation provides a new way to correct the error of radiosonde MEMS humidity measurement caused by solar radiation heating.

The elastic mechanical properties of silicon nanocantilevers are of prime importance in biotechnology and nanoelectromechanical system (NEMS) applications. In order to make these applications reliable, the exact evaluation of the effect of the undercut on the mechanical properties of silicon nanocantilevers is essential and critical. In this paper, a numerical-experimental method for determining the effect of the undercut on resonant frequencies and Young’s modulus of silicon nanocantilevers is proposed by combining finite element (FE) analysis and dynamic frequency response tests by using laser Doppler vibrometer (LDV) as well as static force-displacement curve test by using an atomic force microscope (AFM). Silicon nanocantilevers test structures are fabricated from silicon-on-insulator (SOI) wafers by using the standard complementary metal-oxide-semiconductor (CMOS) lithography process and anisotropic wet-etch release process based on the critical point drying, which inevitably generating the undercut of the nanocantilever clamping. Combining with three-dimensional FE numerical simulations incorporating the geometric undercut, the dynamic resonance tests demonstrate that the undercut obviously reduces resonant frequencies of nanocantilevers due to the fact that the undercut effectively increases the nanocantilever length by a correct value ΔL. According to a least-square fit expression including ΔL, we extract Young’s modulus from the measured resonance frequency versus the effective length dependency and find that Young’s modulus of a silicon nanocantilever with 200-nm thickness is close to that of bulk silicon. However, when we do not consider the undercut ΔL, the obtained Young's modulus is decreased 39.3%. Based on the linear force-displacement response of 12μm long and 200nm thick silicon nanocantilever obtained by using AFM, our extracted Young’s modulus of the [110] nanocantilever with and without undercut is 169.1GPa and 133.0GPa, respectively. This error reaches 21.3%. Our work reveals that the effect of the undercut on the characterization of the mechanical properties of nanocantilevers with dynamic and static test must be carefully considered.

Resource discovery is the key of network resource management, which includes multiple aspects, such as resource description, resource organization, and resource discovery and resource selection. For a long time, communication network resourcehas been lack of unified and standardized description, causing users difficult to precisely find related resources in demand. This paper presents a distributed resource query methods based on management domain, including distributed resource query architecture, the basic process of resource discovery, update method,query methods and so on. The method of network resources makes use of collaborative queries to realize network resource discovery according to need.

Dissolution behavior of238U from low-level contaminated soil was investigated by Acidithiobacillus ferrooxidans (A. ferrooxidans) . It was found that the removal rate of238U by A. ferrooxidans was much higher than that of deionized water. The A. ferrooxidans can promote the dissolution of238U and the removal rate can achieve 94.50 %. Furthermore, the turnover rate of soil nutrients of A. ferrooxidans treated sample was much lower than that of dissolution by deionized water, and the soil fertility was maintained. This work illustrated the efficacy of leaching of uranium by the involvement of bacteria by indirect mechanism.

One single machine learning algorithm presents shortcomings when the data environment changes in the process of application. This article puts forward a heteromorphic ensemble learning model made up of bayes, support vector machine (SVM) and decision tree which classifies P2P traffic by voting principle. The experiment shows that the model can significantly improve the classification accuracy, and has a good stability.

Medium pressure water asphalt heating equipment and hot oil asphalt heating equipment widely used in asphalt concrete mixture are using indirect heating method. In indirect asphalt heating device design, heating coil full of heating medium in asphalt tank and asphalt delivery pipe to next technological tank or asphalt concrete mixing device are key parts for the heating technology. Based on heat-transfer mechanism of heating medium, medium pressure water and hot oil have been compared, and medium pressure water has been chosen as heating medium for better character in heat transmission capability and efficiency. By thermo technical calculation, diameter,length and layout of heating coil have been decided, and structure of asphalt delivery pipe has been designed. Equipment running effect shows pipeline of medium pressure water system is designed reasonably and goal temperature of asphalt can be reached.

Due to the large amount of network data and complex representation, traditional network security behavior recognition system always leads to high redundancy and dimension, resulting in taking up more resources, larger computation. To solve this problem, we do the features selection. This article presents a consensus decision-making method, which combines current famous feature selection algorithms to obtain a more reasonable result and to sort the features in order of importance to facilitate the appropriate selection of features under different conditions. With this method tested on SVM (Support Vector Machine) as classification algorithm, it proves that the algorithm effectively improves the recognition accuracy with fewer features and performs better in terms of result stability.

In many fields such as asphalt concrete pavement, hot and liquid asphalt is a kind of necessary material. Medium pressure water heating is a new method for asphalt storage or heating with advantages such as safety, energy conservation and low pollution. Heating furnace is the key part for this closed cycle system, and two 800KW medium pressure water heating furnaces are adopted to supply enough thermal energy for the heating system to ensure asphalt working temperature. To ensure asphalt storage volume and strength, size and steel plate thickness of asphalt tank are calculated. Three-layer structure of tank wall is designed to reduce heat dissipation, which is of 5mm inner wall and 1mm outer protection layer filled with 60mm rock wool layer.

End plate of some large container is of non-conventional type and rather large size, which is difficult to be formed. To choose fit technology parameters and mould structure, stress is analyzed and bending of shallow stretch forming rule is obeyed. Technology of large container end plate stretch forming in 500 tons oil hydraulic press is researched and one mould manufacturing method is given fit for shallow stretch forming. In this technology, to form convex bottom and improve strength, material-pressure plate is not adopted. To reduce wrinkle and stretch force, 30 degree cone of cavity die is selected. To reduce bending deformation and destabilization, round radius of male punch is 8 millimeters.

Micro-grid, which coordinates distributed energy resources in a decentralized way, is a promising approach to allow distributed energy resources to provide full benefits while reducing the control burden on the grid. By exploiting the concept of cyber-physical system (CPS), prediction can be easily incorporated into micro-grid, which helps the micro-grid work more effectively and safely. In such a case, in this paper, based on CPS, we propose a novel micro-grid model, within the framework of which, a more explicit wind-solar complementary power system is presented. Moreover, we show how the closed-loop control is implemented in the proposed model which is of benefit to the design of micro-grid.

While lots of works have been done regarding low penetration photovoltaic (PV), high penetration PV has not been well investigated in the literature, especially the issues such as supply reliability and power utilization efficiency. In this paper, we first present a modified microgrid model for high penetration PV. Within the architecture of the proposed microgird, we then design a trust based active power matching scheme for efficient power usage. Power factor regulation is also used to keep the microgird running steadily. Finally, simulation results are shown to verify the effectiveness of the proposed scheme.

Development of product innovation design theory, especially the axiomatic design, has changed the pattern depending upon accumulated experience in product design. Independence rule and information rule are the necessary rules of axiomatic design theory. In design of multi-planetary gear transmission, axiomatic design has been applied to determinate type of even-loading mechanism, being important in evenly dividing power into planetary gears to greatly reduce vibration and impact of gear transmission process. By axiomatic design, flexible pin even-loading system and sun gear floating system were compared, and the best scheme has been decided to realize great power transmission.

Silk nanoparticles were easily obtained from regenerated Antheraea Pernyi Silk Fibroin (ASF). The morphology and average size of the silk particles was sensitive to pH value of fibroin solution. The diameter of nanoparticles prepared was in the range of 30 nm to 1000 nm with a narrow size distribution. On this process, the molecular conformation of regenerated ASF changed from α-helix to β-sheet structure. The shape of prepared nanoparticles were regular spherical structure when the pH value was about 4.3 (pI) in ASF solution. Doxorubicin hydrochloride (DOX) was loaded in the ASF particles as drug release model and the drug-loading ratio was 3.4 %. The release rate of DOX from ASF nanoparticles was pH sensitive. After 23 days release, there was still 84% DOX in the ASF nanoparticles. The result suggested that the ASF nanoparticles might be suitable microcarriers for drug delivery.

Boom is one of key components of concrete pump trucks which can be looked as a projecting beam when unfolded at pumping mode. Under different concrete pumping modes, vibration of boom is serious for the hydraulic cylinder switching over shock, which can lead to the early damage of boom structure. In the finite element analysis software, boom of 37 meters concrete pump truck is simulated for its modal. Natural frequencies and corresponding modes are got and analyzed. To reduce vibration of concrete pump trucks, advices are presented by finite element modal analysis.

A numerical study of premixed propane/air flame propagation in a closed duct is presented. A dynamically thickened flame (TF) method is applied to model the premixed combustion. The reaction of propane in air is taken into account using a single-step global Arrhenius kinetics. It is shown that the premixed flame undergoes four stages of dynamics in the propagation. The formation of tulip flame phenomenon is observed. The pressure during the combustion process grows exponentially at the finger-shape flame stage and then slows down until the formation of tulip shape. After tulip formation the pressure increases quickly again with the increase of the flame surface area. The vortex motion behind the flame front advects the flame into tulip shape. The study indicates that the TF model is quite reliable for the investigation of premixed propane/air flame propagation.

Multi-planetary gear transmission is usually used in construction equipment, metallurgical machinery and wind-driven generator. Driving mechanism of heavy-duty equipment without even-loading system is badly loading, resulting in great impact force and severe vibration. To study characteristic of power dividing, multi-planetary gear transmission without any even-loading mechanism and that with flexible pin even-loading mechanism were simulated in commercial gear drive design software and dynamics analysis software. The simulation results are shown in this paper and conclusions are drawn useful for design and manufacture of heavy-duty multi-planetary gear transmission.

In this paper we propose a new approach combines KNN method with FP-growth algorithm for identification and modeling existing dependencies between labels (ML-FKNN). We define and develop an algorithm that, first, utilize FP-growth algorithm for generating the association rules to identifies dependencies among the labels, then divides the whole train set into several mutually exclusive subsets to calculate the mean vectors of the each subset, and selects K nearest label neighbors for test instance by calculating its similarity with the mean vectors of the training subsets , and finally identifies the final predicted label set incorporating the discovered dependencies. Empirical evaluations on benchmark datasets shows that the proposed approach achieves high and stable accuracy results and is competitive with some existing methods for multi-label classification.

In order to investigate the ratio of Zn/Y on as-cast Mg-4Zn-xY (x=1, 2, 3 in wt. %), microstructure and mechanical properties are analyzed by scanning electronic microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrum (EDS) and tensile testing. The results indicate that with the decrease of the ratio of Zn/Y, microstructures are refined more greatly and the spheroidization and uniformity coefficient are improved obviously, and the morphologies of second phases are changed from diversity to unity, resulting in an improvement of mechanical properties of alloys.

The inverse problem is an important interdisciplinary subject, which receives more and more attention in the fields of mathematics, computer science, information science and other applied natural sciences in recent years. Nowadays, the inverse problem is more and more commonly applied than before, e.g., in image processing and geophysics. This trend promotes the development of both the advanced computing methods and high performance computing techniques. The high performance of computing problems for inverse algorithms is discussed in this paper, which is meaningful for the research of applied inversion subjects.

Steel slag vehicles with tilting arm are advanced equipment used in iron and steel factory for short distance delivery. With great impact force and severe vibration when pouring steel slag, strength of equipment structure must be enough. In product design, theoretical study and simulation of steel slag vehicles were completed using commercial finite element software and dynamics software. Static strength and dynamic tests of some steel slag vehicle were finished using dynamic and static stain instruments, acceleration transducer in order to verify the computer analysis result. The modal analysis result of steel slag vehicle, the field dynamic test procedure and data process are shown in this article. In the end of paper, conclusions are drawn useful for design and manufacture of heavy-duty equipment such as steel slag vehicles.

In this paper, developed a non-aluminum die casting magnesium alloys were studied based on Mg-xGd-Y-Zr（x=6, 8, 12 wt.%）alloys in cold chamber press. The microstructures and mechanical properties of die casting GWK alloys have been investigated using OM, SEM, XRD, EDS and mechanical property test. The experimental results show that with increasing Gd content of Mg-xGd-Y-Zr alloys, the tensile strength increase, but elongation decrease. In particular, die casting GWK alloys after short-term and low-temperature solid solution treatment (T4) have a small variation in grain size and more uniform microstructures, and the second phases distribute at the grain boundaries in form of discontinuous rod shape or granule shape, which result in an obvious improvement in tensile mechanical properties of alloys. The Mg-12Gd-3Y-0.5Zr die casting alloy exhibit maximum tensile strength after solution heat treatment, and the value is 269MPa at room temperature. The effect of solution heat treatment on die casting Mg-xGd-Y-Zr alloys was also discussed.

A high strength and toughness extruded Mg-Zn-Y alloy based on quasicrystal-strengthening has been studied. The effect of extrusion and heat treatment on the microstructures and mechanical properties of Mg-Zn-Y alloy were studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrum (EDS), X-ray diffraction (XRD) and tensile testing. The experimental results indicated that the coarse dendrite crystals were broken through the hot extrusion, and dynamic recrystallization appeared during the hot extrusion, which obviously refined the hot-extruded microstructure to the average grain size about 20μm. A large amount of strengthening phases such as Mg3Zn6Y(I-Phase), Mg12ZnY(X-Phase) and MgZn2, which were massive, grainy and clavate, dispersedly precipitated from the matrix along grain boundary during ageing treatment at 225 after extrusion, and made the sliding of grain boundaries restrained, which resulted in an enhancement for mechanical properties to a great extent. At the same time, the tensile strength and yield strength increased after ageing treatment. After ageing treatment of 225×24h, the highest tensile strength and yield strength of the extruded Mg-Zn-Y alloy were obtained: σb=506.7MPa, σ0.2=373.5MPa, which were increased by 104.8% and 120.4%, respectively, compared with the extruded Mg-Zn-Y alloy, however the elongation decreased to 16.52%.

The microstructure and mechanical properties of AZ81-4%Gd magnesium alloy sheet after aging at 150, 200, 250, 300 were analyzed and tested by x-ray diffraction,scanning electron microscope,energy dispersive spectrometer and hardness tester. The results demonstrated that β-Mg17Al12phases were precipitated in two patterns, those were continuous precipitation and discontinuous precipitation during aging below 250 and the morphology of β-Mg17Al12phase was different. The β-Mg17Al12phases were precipitated in the pattern of continuous during aging at 300. The analysis showed that the precipitation pattern and morphology of β phases were related to the mechanism of nucleation and growth. The alloy hardness achieved the highest value after aging at 250 and 300 for 24 hours, the hardness of the alloy was the highest after aging at 150 and 200 for 32 hours. In addition, the observations on microstructure and the testing on hardness revealed that the best aging temperature is 200 for the AZ81-4%Gd alloys within the scope of the study.

Durable press (DP) finishing is the common process to impart anti-creasing properties to cotton fabrics. Conventionally, the whole fabric was treated by pad-dry-cure (PDC) process in one treating bath. However, this process led to the serious loss of the cotton fabrics in mechanical properties. In this work, the cotton yarns were treated with DP finishing solution. And subsequently, they were dried and cured in a certain temperature. The wrinkle recovery angle (WRA) of yarns was measured. The relationship between the treating process and WRA was studied. The affecting parameters on WRA were acquired by experiment. This work provides basic data for people to know and understand the role of anti-creasing yarns in the whole fabric.

A real-time and high precision ultrasonic ranging method is proposed here. Ultrasonic ranging system based on MCU was established, which is composed of MCU, ultrasonic sending and receiving circuit, temperature compensate circuit, alarm, key and display circuit. Counting pulse method was used to measure the ultrasonic transmission time, and then the distance is calculated. In order to improve the ranging accuracy, temperature compensation was used in this system. Preliminary experiment showed that the system meet the requirements. This system has advantages such as low price, small volume, reliable operation, high accuracy, and can be employed in car backing, obstacle avoiding of robots, industrial logging, reservoir level measuring etc.

Data stream mining has been applied in many domains, but the concept drifts of data streams bring great obstacles to data mining. Current researches about classification algorithm for streaming data with concept drift have achieved many successes, while they pay little attention to the iterancy of data streams, namely, the situation of the historical concept reappears. For this characteristic, this paper puts forward that it utilizes the classifier model of the historical concepts or high similarity concepts through calculating the concept similarity to classify and predict. In this way, we don’t need training any more. Meanwhile, it reduces the cost of update model, speeds up the classification of the rate and improves the prediction efficiency.

Antheraea pernyi silk fibroin (ASF) solution was prepared by dissolving Antheraea pernyi silk fiber in lithium thiocyanate solution. The ASF/glycol blend films were prepared by casting aqueous solution of ASF mixed with glycol. The structure of blend film was investigated by the X-ray diffraction method and infrared spectroscopy. The result showed that the structure of regenerated ASF film was α-helix and random coil conformation. After mixing with glycol, it resulted in significant increase in β-sheet structure with the improvement of water resistance of the films. This effect was strongly dependent on glycol content in the blend film. When the glycol content was more than 45 wt%, the structure of ASF changed to β-sheet and the film became water-insoluble. The breaking strength and elongation of ASF/glycol blend film were 30 Mpa and 50 %, respectively. In summary, the ASF/glycol blend film provided a great potential as a biological material.

260T hot-metal car is a huge shape machinery product used in iron and steel plant for the short distance transportation. The work conditions of the hot-metal car are bad, so the reliability of the product structure must be guaranteed. During the structure design, theoretical study and computer simulation analysis of the car frame are taken using the commercial finite element software. The tests for the 260T hot-metal car product are accomplished by using the modern static testing technology to verify the theoretical calculation. The paper describes the test scheme and field test process, extracts the strain and stress value of key points on the car frame and analyses the test data. At last, the test result data are compared with the finite element computation result data, verifying the theoretical calculation.

It is importance to be able to predict the hot tearing tendency for multicomponent magnesium alloys. Hot tearing is one of the most common and serious defects that occurs during the solidification of commercial magnesium alloys. Clyne and Davies correlated the susceptibility-composition relationship in binary systems based on the concept of the existence of critical time periods during the solidification process when the structure is most vulnerable to cracking. The present work first evaluates the hot tearing susceptibility (HTS) of binary Mg-Zn system using thermodynamic simulations based on Clyne-Davies’ model, a typical “λ shape” curve is obtained. And then a scaling factor is investigated to obtain the internal-consistent cracking susceptibility coefficient for further investigating the addition of aluminum on the HTS in the ternary Mg-Zn-Al system. The predicted hot tearing tendencies is consistent very well with the experimental results of the Mg-Zn binary system and Mg-Zn-Al ternary system.

Regenerated Antheraea Pernyi silk fibroin (ASF) solution was prepared by dissolving Antheraea Pernyi (A. pernyi) silk fiber in lithium thiocyanate solution. Atomic force microscopy (AFM) examination showed that there were many short nanofibers in regenerated ASF solution, which were made up of 10-20 nm nanospheres. In this paper, we discussed the formation mechanism of these nanofibers. The results of the surface tension showed that ASF had surface active and can significantly decline the surface tension of water from 73 mN/m to 51 mN/m. The hydrophobic side chains of ASF molecular would try to break away from water environment and thereby undergo self-assembly into nanospheres. And then, these nanospheres arrange into a short nanofiber. Then, the ASF nanofiber film was prepared by casting regenerated ASF solution blended with glycol. The structure of ASF was β-sheet and the film was water-insoluble. This blend film not only had excellent mechanical properties, but also can be biodegradated by enzyme in vitro. All of this indicated that this new regenerated ASF nanofiber film not only provided excellent biocompatibility, but also had large surface as extracellular matrix (ECM) to cell adhesion. The film made of nanofiber was similar to ECM on the nanoscale, which promoted cell migration and proliferation. In summary, it provided a great potential as a biological material.

Antheraea pernyi silk fibroin (ASF) solution was prepared by dissolving Antheraea pernyi silk fiber in lithium thiocyanate solution. The ASF/1,4-butanediol (ASF/BDO) blend porous materials were prepared with freeze-drying method. The structure of ASF was investigated by the X-ray diffraction method. The result showed that the structure of regenerated ASF scaffold was α-helix and random coil conformation. After ASF mixed with 5 wt% BDO, the structure of ASF was changed to β-sheet and the ASF scaffolds became water-insoluble. There were some small pores and fibrous structure in the big pores and the surface of pores was rough with a great many raised particles. The scaffolds with the average pore size of 300-1000μm and the porosity of 82-92% can efficiently be produced in this paper. Due to avoid the use of organic solvents or harsh chemicals, these new ASF based porous materials provide much more excellent biocompatibility and is expected to be applied to tissue regeneration scaffolds.

The conventional k-means algorithms are sensitive to the initial cluster centers, and tend to be trapped by local optima. To resolve these problems, a novel k-means clustering algorithm using enhanced differential evolution technique is proposed in this paper. This algorithm improves the global search ability by applying Laplace mutation operator and exponentially increasing crossover probability operator. Numerical experiments show that this algorithm overcomes the disadvantages of the conventional k-means algorithms, and improves search ability with higher accuracy, faster convergence speed and better robustness.

Different sterilization techniques such as Co(60) gamma irradiation and autoclaving were used to treat the regenerated Bombyx mori silk fibroin (RSF) in aqueous solutions. The effect of the two above mentioned sterilization methods on the conformational changes and gelation rate of RSF was studied. According to the analysis of circular dichroism spectroscopy, gamma irradiation may initiate the conformational transition from random coil to β-sheet for RSF, while autoclaving shows less significant influence on the structure changes of RSF in aqueous solutions. The results also indicate that gelation time decreased to 5 days after γ-irradiation treatment while gelation time increased to 31 days after autoclave treatment. Moreover, particles of RSF in solutions changed larger and gelation time increased when autoclaving treatment time extended. However, no detectable changes of RSF secondary structure were found investigated by XRD and FTIR. Which indicated that under both sterilization methods, the RSF structure was transformed from random coil to β-sheet structure after gelation.

Due to the exceptionally desirable properties, Chebyshev polynomials have been recently proposed for designing public key cryptosystems. However, some proposed schemes were pointed out to be insecure and unpractical. In this paper, we analyze their defects, discretize the Chebyshev maps, generalize properties of Chebyshev polynomials and design an improved scheme. Theoretical analysis shows that it possesses higher security than RSA and experimental results shows it can be implemented easily.

The dynamic deformation behavior of an as-extruded Mg-Gd-Y magnesium alloy was studied by using Split Hopkinson Pressure Bar (SHPB) apparatus under high strain rates of 102 s-1 to 103s-1 in the present work, in the mean while the microstructure evolution after deformation were inspected by OM and SEM. The results demonstrated that the material is not sensitive to the strain rate and with increasing the strain rate the yield stress of as-extruded Mg-Gd-Y magnesium alloy has a tendency of increasing. The microstructure observation results shown that several deformation localization areas with the width of 10mm formed in the strain rates of 465s-1 and 2140s-1 along the compression axis respectively, and the grain boundaries within the deformation localization area are parallel with each other and are perpendicular to the compression axis. While increasing the strain rate to 3767s-1 the deformation seems become uniform and all the grains are compressed flat in somewhat. The deformation mechanism of as-extruded Mg-Gd-Y magnesium alloy under high strain rate at room temperature was also discussed.

The optimal conditions of production of biopolymer by the culture of Bacillus sp.were examined, using molasses wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in molasses wastewater favorable for the growth of the Bacillus sp.was 4500 mg•L-1, and inoculum size of 6%(v/v), 28◦C, initial pH 7.0 and shaking speed of 160 r•min-1, under the optimal culture conditions, the highest flocculating activity achieved for Kaolin suspension was 97.5% and 4.0 g biomass /L broth was obtained. The Bacillus sp. biomass was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G and reactive Turquoise Blue KN-G with a decolorization efficiency of 98.5 and 92.5%, respectively, using 20 mL of the flocculant in 500 mL of 100 mg•L-1 dye solution.

The investigation on fatigue behavior and fracture surfaces of fatigued specimens of as-extruded AZ31 magnesium alloy can provide a reliable theoretical foundation for both fatigue resistant design and reasonable application of magnesium alloys. Through total-strain-amplitude controlled fatigue tests and analysis on fracture surfaces of fatigued specimens, the behavior of cyclic stress response and fatigue life as well as fracture mechanism were identified for as-extruded AZ31 magnesium alloy. The experimental results show that the extruded AZ31 alloy exhibits significant cyclic strain hardening, the relation between elastic strain amplitude, plastic strain amplitude and reversals to failure can be described by Basquin and Coffin-Manson equations respectively. In addition, it has been found that fatigue cracks initiate and propagate in a transgranular mode.

The high strain rate compression behavior of extruded Mg-Gd-Y magnesium alloy was tested by split Hopkinson pressure bar (SHPB) under the strain rates of 465s-1，2140s-1and 3767s-1. As comparison the quasi-static compression behavior was tested in the meanwhile. The results show that the quasi-static yield stress is equivalent to that of high strain rates, but the flow stress at high strain rates are higher than that of quasi-static stain rate at the same strain. When the strain rate is increase from quasi-static to high strain rates the deformation stresses increase obviously but within the present testing high strain rates, increasing the strain rate the stress has a slight increasing, indicating that at high strain rate the stress of Mg-Gd-Y magnesium alloy is not sensitive to the strain rate. The constitutive equation between deformation stress, strain and strain rate was build based on the tested compression stress strain curves. The calculated stress strain data were compared with tested stress strain curves. The results demonstrate that when the strain rates are 0.001s-1，465s-1，2140s-1respectively the calculated and experimental data are fit very well. The calculated stress is higher than that of tested stress if the strain rate is increase to 3767s-1and the strain is more than 0.15. The discrepancy was explained through the physical soundness of Johnson-Cook model.

The optimal conditions of production of biopolymer by the culture of Bacillus cereus B-11 were examined, using molasses wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in molasses wastewater favorable for the production of the biopolymer was 5000 mg•L-1, and inoculum size of 5%(v/v), 28◦C, initial pH 7.0 and shaking speed of 150 r•min-1, under the optimal culture conditions, the highest flocculating activity achieved for Kaolin suspension was 98.5% and 3.55 g biopolymer /L broth was obtained. The biopolymer was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G and reactive Turquoise Blue KN-G with a decolorization efficiency of 97.5 and 94.7%, respectively,using 25 mL of the flocculant in 500 mL of 100 mg•L-1 dye solution.

The study described the sorption of Cd(II) by a novel extracellular biopolymer (B-11) produced from Bacillus cereus B-11. The effect of experimental parameters such as pH, initial concentration and contact time, sorbent dosage on the sorption was studied. The langmuir isotherm better fitted the sorption data, the maximum adsorption capacity was 80.64 mg.g-1. The kinetic rates were best fitted to the pseudo-second-order model. It was concluded that the prepared B-11 can be used as an effective and environmentally friendly biosorbent for the removal of Cd(II) ions from aqueous solution.

The optimal conditions of production of biopolymer by the culture of Pseudomonas fluorescens were examined, using brewery wastewater to replace glucose as carbon source and energy source in the culture medium. Results showed that the COD concentration in brewery wastewater favorable for the production of the biopolymer was 6000 mg•L-1, and an optimal culture condition of inoculum size of 5%(v/v), 28°C, initial pH 7.0 and shaking speed of 150 r•min-1, under the optimal culture conditions, the highest flocculating activity achieved for Kaolin suspension was 97.5% and 3.67 g biopolymer /L broth was obtained. The biopolymer was effective in flocculating some soluble reactive dyes in aqueous solution, reactive Light-Yellow K-4G and reactive Turquoise Blue KN-G with a decolorization efficiency of 95.8 and 96.2%, respectively，using 25 mL of the flocculant in 500 mL of 100 mg•L-1 dye solution.The decolorization efficiency was dependent on the flocculant dosage and solution pH.

Using La(NO3)3•nH2O and Ni(CH3COO)2•4H2O as starting materials, alcohol mixed with methoxyethanol as solvent, the LaNiO3 (LNO) solution was prepared. Using this solution, conducting LNO films with sheet resistance of 10Ω were obtained. XRD and HRTEM indicate that the LNO films are epitaxially grown on LaAlO3 (LAO) substrates. Using Pb(CH3COO)2•3H2O, La(NO3)3•nH2O, Ti(OC4H9)4, Zr(OC4H9)4 as starting materials, the PZT films were prepared on the LNO films. The PZT films are c-oriented. The as-prepared PZT film has a remanent polarization of 34.7µC/cm2, superior to the PZT film with random orientation and a remanent polarization of 18.4µC/cm2 prepared on ITO/quartz substrate.

The Ni(II) biosorption characteristics of Pseudomonas fluorescens biomass was examined as a function of initial pH, contact time and initial metal ion concentration. The pseudo-second-order kinetic model was found to be well suited for the entire adsorption process of Ni(II) on biomass. Adsorption equilibrium studies showed that Ni(II) adsorption data followed the Langmuir model, the maximum binding capacity of Ni(II) was 84.45 mg/g at pH 7.0 , shaker speed 150 rpm, at 27 °C. FTIR spectra showed that the principal functional sites taking part in the sorption process included carboxyl , hydroxyl groups and -CH3 stretching groups, the mechanism analysis showed that the chemical chelating was the main adsorption form, electrostatic attraction hydrogen bonding in the process of adsorption. The present study indicated that Pseudomonas fluorescens biomass may be used as an inexpensive, effective and easily cultivable biosorbent for the removal of Ni(II) ions from environmental and industrial wastewater.

In the present study we reported the feasibility of extracellular biopolymer(PF01) produced by Pseudomonas fluorescence as an alternative biosorbent to remove Cu(II) ions from environmental wastewater. The ability of PF01 to remove the Cu(II) ions was investigated by using batch biosorption procedure. The effects such as pH, dosage of biosorbent, Cu(II) initial concentration and sorbate–sorbent contact time on the adsorption were studied. The pseudo-second order kinetics and Langmuir isotherm models were noted be fit to the experimental data. The maximum Cu(II) adsorption capacity was 78.99 mg/g at pH 5.0 , at 28°C. The carboxyl , hydroxyl and amino groups of the PF01 were involved in chemical interaction with the Cu(II) ions depicted by Fourier transform infrared spectroscopic (FTIR). The study points to the potential of new use of extracellular biopolymer PF01 as an effective biosorbent for the removal of Cu(II) from environmental wastewater.

The effect of Ga on the microstructure and mechanical properties of Mg-8wt.%Al alloy at room temperature were investigated by SEM and X-ray analysis. The microstructure of as-cast Mg-8wt.%Al alloy was consist of α-Mg matrix, β- Mg17Al12 and α+β eutectic phases. The primary β- Mg17Al12 phase precipitate along the α-Mg matrix grain boundary and in the discontinuous reticular shape. Ga addition in the as-cast Mg-8wt.%Al alloy change the microstructure significantly. When the addition is less then 2% Gd could be detected and distributed mainly within β- Mg17Al12 phase and in the interface of α-Mg matrix and β- Mg17Al12. With increasing Ga content α-Mg matrix grains and β- Mg17Al12 phase are refined. The amount of α+β eutectic structure increase as well. The holes within β phase are diminished. When Ga content was more than 2% with increasing of Ga content β phase was broken along the concentration of Ga. With the increase of Ga content to 4%, a new phase of Ga2Mg form in the microstructure and β phase precipitate in the shape of smooth baboon along the grain boundary. The mechanical properties test showed that as-cast Mg-8wt.%Al-2wt.%Ga alloy has the optimum combination of ultimate tensile strength of 248 MPa and elongation of 10%.