Abstract:In order to measure the axis perpendicularities, axis intersections, and alignment errors of five-axis simulator, the measuring principle of vertical axis′s perpendicularity vs. horizontal plane and the way of leading to rotation axis line with a theodolite and crosshair targets or filaments was introduced, in which the vertical axis system cannot rotate in full circle. Based on the measurement of the plumb errors of yaw axis lines of the three-axis simulators and the two-axis simulator, then an elementary coordinate system fixed on the theodolite was established by adjusting the pose of theodolite. By fixing crosshair targets A and B on the two ends of pitch axis of three-axis simulator, C and D on roll axis of 3-axis simulator, E and F on pitch axis of two-axis simulator, these three axis lines were led to by theodolite and crosshair targets. Then S₃ and S₂ filaments were mounted on the ends of two yaw axes of 3-axis and 2-axis turntables′, and two points on these two yaw axis lines were also led to by two theodolites. Finally the perpendicularities, axis intersections and alignment errors are achieved by the leading axis lines or points on the axis lines. Accordingly, the measurement error analysis is conducted and the validation of this method is achieved.

Abstract:To improve the guidance precision of far range autonomous proximity of non-cooperative target under double line-of-sights (LOS) navigation in geostationary orbit (GEO), a formation proximity method is proposed by using particle swarm optimization (PSO) multiple impulses guidance law. More specifically,this method transforms the two impulses C-W guidance law into multiple impulses C-W guidance law with mid-correction. Then, the multiple impulses of fixed-time fuel optimal problem is presented under the constraints, and a PSO algorithm with two fitness functions is introduced to solve the multi-objective optimization problem with constraints of guidance precision and double LOS. Numerical simulations are studied to verify effectiveness and feasibility of the PSO algorithm of multiple impulses guidance under different conditions.

Abstract:In order to study the influence of parameters on mechanical performance of stratosphere non-rigid airship, Sobol’ method which is a global sensitivity analysis method based on the Latin hypercube sampling is used for analyzing the multi-parameter sensitivity. The global sensitivities of material parameters, load parameters and configuration parameters to the static performances and the vibration characteristics are analyzed. The influence laws of the main sensitive parameters on the maximum equivalent stress, the maximum deformation and frequencies are analyzed based on the single parameter changing. The research indicates that the sensitivities of membrane surface density and sling parameters to the static performances can be neglected. The sensitivities of sling parameters to the vibration characteristics can be neglected. Local mechanical properties can be effectively improved by increasing slenderness ratio, membrane thickness, membrane elastic modulus or decreasing pressure at the radial lowest point. The anti-deformation capacity of waist can be effectively improved by increasing the pressure at the radial lowest point or decreasing slenderness ratio.

Abstract:Composite structures in service are usually subject to complex loading conditions that can induce a stress field with two or even three dynamic principal stresses. The experimental analysis of composite structures could approximate the real loading condition to produce a multiaxial stress field for validating the load carrying capability. Based on the microstructure of the composite laminates reinforced by non-crimp unidirectional carbon fiber fabrics, specimen of biaxial compression was designed and followed by the testing under uniaxial and biaxial compression as well. Comparative analysis was also carried out for the mechanical behavior of the composites reinforced by unidirectional carbon fiber fabrics under different compression loads. The results show that the composites performs linear compression behavior and brittle fracture, and the failure mechanism of composite is overall represented as shear buckling under uniaxial compression. Compared with uniaxial compression, although the composites still performed linear compression behavior and brittle fracture under biaxial compression, its stress-strain curves showed some nonlinear characteristics. The strength of composites under biaxial compression was much lower than that of the uniaxial compression results. Resistance to deformation of the composite was enhanced when the biaxial compression loading was kept at 1∶1, resulting in the increasing of the compression modulus. The result was opposite while the biaxial compression loading was kept at 2∶1. The failure mechanism of the composite was basically the same when the biaxial compression loads were kept at 1∶1 and 2∶1, mainly as matrix cracking, fiber breakage and interlaminar debonding. Especially, the phenomenon of interlaminar debonding was obvious.

Abstract:To satisfy the constrain of structure space of flexible trailing edge, the single cable transmission mechanism is designed in this paper. The nonlinear differential equations coupled by the mid-plate and single cable are derived, and the solving approach and the calculational example are given. The results show that the single cable can be actuated any deformation of the flexible trailing edge within the deflection angle between 0° and 20°. The linear relationship between the deflection angle and the driving force is good. So is the deflection angle and the displacement of cable. The pressure load on every limit pulley increases as the deflection angle increases. The maximum pressure load exerted on the limit pulley is about 20％ of the input force.

Abstract:The Multi-UAVs cooperative path planning has a complex search space in 3D environment, while the cooperative of Multi-UAVs is very hard to deal with. So a novel cultural algorithm based on spatial fuzzy set and differential evolution is proposed in this paper. The proposed approach uses fuzzy set to present spatial grid points in 3D, so that the key way-points on path should be paid more attention. Then the spatial fuzzy knowledge, history knowledge and cooperative knowledge that contained in the belief space of cultural algorithm prune the search space of Multi-UAVs path planning. Moreover, this approach uses differential evolution as the population space of cultural algorithm to generate the optimal solution, while it satisfies the constraints of multi-UAVs cooperative. The differential also extends the belief space with the unknown information of spatial to ensure the population diversity. In addition, the cultural algorithm exchanges the shared information, so that it accumulates the knowledge and revises the searching direction. The simulation results show that the spatial grid points based on fuzzy set enhance the efficiency of key way-points selected, and the cultural algorithm could explore more unknown space out of spatial grid such that it avoids the search fall into local optimization. Cooperative knowledge is also introduced to satisfy the requirements of Multi-UAVs cooperative to planning feasible paths for Multi-UAVs cooperative quickly.

Abstract:It is reported that the preparation of Co₃O₄-Pt/graphene hybrid and its use as air cathode catalyst for enhanced specific capacity in Lithium-air battery. Co₃O₄-Pt/graphene was synthesized by a two-step method. More specifically, Pt/graphene was prepared by microwave-assisted polyol process, and then it was mixed with Co₃O₄ uniformly to get highly efficient Co₃O₄-Pt/graphene as air-cathode catalyst. Micromorphology, composition and compositional dispersion of the obtained hybrid catalyst were then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (XEDS), transmission electron microscopy (TEM),Raman Spectroscopy(Ram). Co₃O₄-Pt/graphene air cathode catalyst was assembled with metal lithium anode, LiPF₆/EC-DMC-EMC electrolyte, and PP/PE/PP to construct a lithium-air battery. The constant current charge-discharge tests of the lithium-air battery exhibit enhanced specific capacity: the discharge specific capacity reaches up to 8 000 mAh/g and the voltage is above 2.6 V, which is superior to alternative cathode catalysts. The enhanced performance of lithium-air battery is attributed to the joint effect of preparation process, composition, and compositional dispersion.

Abstract:Togeta more accuratemodel ofcutting powerand improve the ability of evaluating energy consumption of machine tool and energy optimization, this paper takes face milling for example, chooses gray cast iron as the work-piece material, adopts four factors (spindle speed, feed rate per tooth, milling depth and milling width) and four levels orthogonal experiment and carries out cutting experiments ina machining center, obtains the cutting power by the power data acquisition device.The experimental results and model accuracy assessment show that when the coating milling cutter of W400F-FS cuts HT250 gray cast iron, specific energy and empirical formula of cutting force calculate cutting power with the average relative error of 16.06% and 32.63%respectively, but the fit cutting power model with the average relative error of 3.7% is achieved by SPSS software. The problem of calculating cutting power through specific energy and empirical formula of cutting forcewith much error is solved.

Abstract:High-speed train gearbox shell is an important component of high-speed train. In order to protect the operational safety of high-speed train gearbox shell, it is needed to detect the casting internal defect as product testing and maintenance inspection accurately and rapidly. In this paper, based on three-dimensional CT technology the test was developed to detect the casting defects of high-speed train gearbox shell; through the analysis of three-dimensional data of the four kinds detects, three-dimensional geometric features and characteristic values were obtained, and the Adaboost_BTSVM algorithm were used to achieve the automatic classification of casting defects of high-speed train gearbox shell. The according classification accuracy of shrinkage defects can be 85%, and the classification accuracy of crack defects can stand at 100%. These will provide an available automatic identification method for the defect of high-speed train gearbox shell.

Abstract:In order to ascertain superplastic mechanism and establish constitutive equation, strain rate sensitivity exponent (mvalue) is required to be calculated. Fine-grained AA7075 aluminum alloy sheets were fabricated by casting, rolling and annealing, and variation in the mvalues were investigated by high temperature tensile machine and image analyzer. Aiming at the superplastic deformation of materials with the equiaxed grain and the elongated grain microstructures, the relations between the mvalue and the strain were modeled. It is noted that the mvalue for the equiaxed grain microstructure decreases with increasing the strain during constant velocity tension, and the mvalue for the elongated grain microstructure increases with increasing the strain during superplasticity. Theoretical predictions were verified by the superplastic experimental evidence in AA7075 alloy and AA7475+0.7Zr alloy with fine equiaxed grains and in Mg-8.5%Li alloys with the elongated grains and AA7475 alloy with low angle grain boundaries. The calculated results agree well with the experimental ones, and it is shown that variation in microstructure leads to the variation in the mvalue.

Abstract:The paper discussed the effects of ceramic polishing powder, a type of supplementary cementing material, on concrete frost resistance. More specifically, two kinds of concrete (without air entraining admixture and with air entraining admixture) were developed, and for each case, there were 12 groups of concrete, including 1 group of control concrete, 4 groups of concrete mixed with ceramic polishing powder, 4 groups of concrete mixed with fly ash, and 3 groups of concrete mixed with ceramic polishing powder and fly ash simultaneously, but the cement substitution rate in each group were different. The concrete frost resistance tests were carried out, and some valuable results are obtained. Firstly, when there is not mixed air entraining admixture, the frost resistance of concrete with ceramic polishing powder is the best one, in which the substitution rate of cement with ceramic polishing powder is 30%, and with other substitution rate, the frost resistance of concrete with ceramic polishing powder is the same as that of control concrete. Secondly, when there is not mixed air entraining admixture, the frost resistance of concrete with fly ash is better than that of concrete with ceramic polishing powder, in which the substitution rate of cement with fly ash is 20%, and with other substitution rate, the frost resistance of concrete with ceramic polishing powder is the same as that of concrete with fly ash. In addition, when there is not mixed air entraining admixture, the frost resistance of concrete mixed with ceramic polishing powder and fly ash simultaneously is the same as that of concrete mixed with either. Finally, air entraining admixture can improve the frost resistance of ceramic polishing powder concrete obviously. Therefore, frost resistance of concrete mixed with ceramic polishing powder is the same as or better than that of control concrete.

Abstract:Simulation system was developed, in order to achieve the purpose of offline functional debugging and optimization for the plate rolling line automation system. For the system, it was designed based on the object-oriented technology. Plate mill line was divided into equipment object, instrument object and plate piece object, in which single object attributes are updated by private service and different objects are associated through public property. Based on process control system platform environment, multi-thread structure was used to meet the simulation requirements of multiple process areas. Time trigger was used to control simulation time step, and actual rolling process data can be generated through data playback method. The process from putting slab online to end of rolling was simulated. The developed simulation system was used for one practical project, and the offline commissioning requirements were satisfied well.

Abstract:In order to solve the problem of GFRP tube in practical engineering, two or more than two GFRP tubes were spliced together and the mechanical properties of the joint were guaranteed. The experimental research on the mechanical property of continuous reinforced concrete-filled GFRP tubular specimen and splicing composite columns connected with steel bars, steel plates and steel tubes subjected to axial loading was conducted, and the results showed that the white stripes appeared on the surface of GFRP tube when the load respectively reached about 35%P_u (P_u -limit load), and the confinement effect of GFRP tube began to produce when the load reached 65%P_u. With continued loading, the confinement effect still existed, and the failure of splicing specimens with GFRP tube was a symbol, and the splicing specimens occurred near the end of connectors around 250 mm. Relatively, the failure of the continuous specimen occurred in the middle position along the length direction of the specimen. The chosen connecting ways with three methods could ensure the normal work of splicing reinforced concrete-filled GFRP tubular composite columns under axial compression.

Abstract:For the problem of severer flight delays, based on the relative research achievements in domestic and aboard, this paper proposes a two-stage method for extracting flight delay patterns. Firstly, this method uses the phase-space reconstruction theory and Recurrence Plot to analyze the chaotic characteristics of flight delay rate. Then, after acquiring the delay time subsequences, the Recursive Quantitative Analysis and K-means Clustering technology were used to extract flight delay patterns, and the characteristics of time-varying of flight delay patterns were analyzed. Finally, the example verifies this method can not only effectively extract flight delay patterns, but also can get the time-varying characteristics of the patterns. The result provides managerial and decisive reference of prediction and warning of flight delay for airports and airlines.

Abstract:In order to solve the performance limitations of traditional ship-type and prismatic FPSO, a novel concept of docking pyramidal FPSO is presented. For the new floating body, five independent shape parameters are presented to decide the geometry of floating body and also affect the basic functions and hydrodynamic performance of FPSO. Then boundary element method based on potential flow theory is applied to analyze the motion response of docking pyramidal floating body in wave. Furthermore, the effect of shape parameters on the hydrodynamic performance of FPSO is qualitatively studied, and the design guideline of the new floating body is also proposed to improve the heave motion performance based on wave potential flow theory and engineering approximate method. Finally, the new floating body can be designed according to the basic functions of an octagon FPSO, and the comparison results show the performance advantages of docking pyramidal FPSO and the rationality of design principle in this paper provide effective engineering equipment and solutions for deep-water oil and gas development.

Abstract:In order to study the influence of transition zone length on stretching bending, in this paper, typical asymmetric aluminum profile used in high-speed train was selected as the research object, and stretching bending research of four different transition zone length was carried out. Numerical simulation was used to analyze and compare stress and strain distribution, shape error, springback, cross-section distortion and spatial twist, and the forming defects index was defined to characterize the integrated forming effects. The results reveal that an increment of the post-stretching elongation leads to small shape error and springback but large cross-sectional distortion and spatial twist. The forming defects index illustrates that a 200 mm transition zone leads to the least forming defects for stretching bending. The 0.618 method was used to optimize transition zone length. Experimental validation was also conducted on stretch-wrap bending machine to show the consistence with the numerical analysis.

Abstract:The flow control and drag reduction in a turbulent channel flow by using a spanwise travelling wave Lorentz force are investigated numerically via the direct numerical simulation (DNS). The evolution of the streaks and the vortex structures adjoining the wall in the turbulent channel flow controlled by Lorentz force are described. Moreover, normal fluctuation velocity, streamwise fluctuation velocity distribution, the average Reynolds stress distribution and the spectra analysis of Reynolds stress are also discussed simultaneously. The results show that, under the action of the distributed Lorentz force with proper control parameters, only well-organized strip-shaped streamwise vortexes are observed in the near-wall region of the turbulent channel flow, and the others vortexes are almost disappeared, which is the same as the streaks in the near-wall region. Besides the Reynolds stress in the controlled channel flow was inhibited sharply by the spanwise travelling wave Lorentz force which leads to the reduction of skin-friction drag. The mechanism of turbulence drag reduction controlled by using a spanwise travelling wave Lorentz force is further clarified.

Abstract:To obtain anti-plane elastodynamic analytic solution of a semi-circular cylinder, subject to anti-plane point source loading in a vertical bound of an elastic quarter space, image method and wave function expansion method are employed to study steady state scattering of the semi-circular cylinder and interaction of bounds, then displacement and stress are determined in this quarter space. More specifically, firstly, the quarter space is extended as a half space, and the semi-circular cylinder is also extended as a circular cylinder. Then, displacement wave is constructed as series form of wave function and circular cylindrical bound is expanded as Fourier series to determine coefficients of wave function finally. Dynamic stress distributed around circular cylinder is calculated to show that scattering of the semi-circular cylinder is apparently to distinguish front and back, and relative low frequency of loading usually causes more dynamic stress around the semi-circular cylinder, and material parameters also have two widely divergent influences on the radial and circumferential dynamic stress distribution. This steady state solution is presented to enrich SH wave scattering theory and to formulate Green function method for SH wave scattering of bi-material interfacial circular cylinder with theoretical analysis. Numerical calculating examples demonstrate the related engineering problem for underground engineers, earthquake engineers, geotechnical engineers and civil engineers as well.

Abstract:The starting up of onboard SSR is slow and the management is unreliable ,they can not satisfy the demand of the mission which is becoming more and more complex and flexible. To solve the problem, this paper focuses on the index establishing mechanism for onboard Solid State Recorder (SSR), a quick initialization method for onboard massive capacity SSR based on NAND FLASH is proposed by analyzing the advantages and disadvantages of traditional scheme, the requirement of on-orbit operation and control, and working mode, etc. The proposed method uses the design of reserved area and corresponding booting process on the basis of the original NAND FLASH indexing mechanism by space area, which largely reduced the organization time for index table. By considering the memory error caused by single particle effect, the index information in the reserved area of NAND FLASH uses reliability methods including ECC coding, redundancies and partition storage to improve the reliability of the index table. The restart working mechanism and the update of different mode for the reserved area of application is firstly introduced. Followed by the description of the scanning mode in both functional restart and fault restart, and a mathematical model is built to prove the effectiveness, and is verified in a platform established using Orbita NAND FLASH. Finally, in the designed platform the functional restart of the algorithm takes 3.643 ms and the fault restart takes 73.985 ms while the traditional algorithm takes 50.37 s, which demonstrate that the proposed algorithm significantly reduces the mounting up time.

Abstract:In order to assess the influence of combat organizational structure on operational effectiveness dynamically, the network characteristic of combat organizational structure on condition of information was analyzed by using complex network theory. Considering the heterogeneity of combat organizational entity and organizational structure relation, a multi-dimensions weighted operational network model was firstly constructed, and then the characteristic value of cooperative gain, which depicts the performance of operational network, was defined. Under this, to enhance operational effectiveness, two dynamic evolution models of operational network, which are random evolution model and preferred evolution model, were designed, and the internal relation and influence law between operational network dynamic evolution and operational effectiveness was analyzed by using the models along with the characteristic values of cooperative gain. Finally, simulation results show the feasibility of the proposed method, which can be used to provide theoretical basis for designing and optimizing combat organizational structure.

Abstract:This paper proposes a DSmT & wavelet packet energy analysis fusion method for the problem of reactor core hanging basket fault information. Three kinds of vibration signals in fault conditions from fastener bursting, fastener parts falling off and heat treatment deformation are analyzed and investigated. Then the extracted fault signal frequency band energy based method is directly used and assigned the collected data to DSmT reliability function. The experimental results show that diagnostic accuracy of DSmT is superior to sub-band energy vector graphics, and DSmT can effectively identify hanging basket failure mode with high diagnostic efficiency and reliability.

Abstract:In order to enlarge a low resolution image clearly, an improved Papoulis-Gerchberg super-resolution method was proposed to solve the space complexity and the edge blurring phenomenon of reconstruction results. More specifically, the proposed algorithm uses edge detection operator, and canny detection is also joined in every Papoulis-Gerchberg iterative process, while reconstruction error is projected to next iterative process, such that the space complexity can be reduced and the lost high-frequency edge information can be recovered effectively. MATLAB experimental results show that the PSNR and the gray standard deviation improve 0.5 dB and 2.5, respectively, with comparison to the conventional Papoulis-Gerchberg method. Furthermore, the proposed algorithm can reconstruct multi-frame Low-Resolution images of same scene more accurately and the visual quality of the reconstruction image is clearer that the conventional one, and the proposed algorithm can also eliminate edge shadow and obtain a clear high-resolution image.

Abstract:To study the seismic behavior of interior joints of high-strength concrete frame structure, 10 interior joints with construction joints of high-strength concrete frame structure are carried out based on the low-cycle loadings test. The influences of the axial compression ratio, concrete strength grade of core area of interior joints, and the length of high-strength concrete in columns and joints extends to beams are studied. Failure characteristics, bearing capacity, displacement ductility and hysteretic curves are also analyzed deeply. Test results show that all of the interior joints are damaged at the end of beam by bending. The lengths of high-strength concrete in columns and joints extension to beams have little effect on yield load, peak load and hysteretic curves as well. While the length of high-strength concrete in columns and joints extensions to beams have significant effect on displacement ductility. On the basis of the test results analysis and construction factors, it is shown that 1.5his the optimal length of high-strength concrete in columns and joints extension to beams.