Abstract:The ventilated cavitation is first predigested to be an air suspension, and then, based on the theory of added mass and air suspension, the FSI vibration equation of ventilated cavitating underwater vehicles is deduced. The change of natural frequency of underwater vehicle, which is enwrapped by ventilated cavitation of different length, is computed, and the influences of ventilated cavitation on vibration of underwater vehicles are investigated. Based on these, the response of structure, impacted by a transverse force, has been analyzed. The results reveal that the natural frequency of structure increases wavily as well as the increment of the length of ventilated cavitation. It is also found that the first step mode frequency is influenced mostly by the elasticity of ventilated cavitation, besides, the influence of ventilated cavitation becomes weaker with the increase of mode step; Under the impact force, the response of amplitude becomes smaller and the response of frequency becomes bigger with the increment of the length of ventilated cavitation.

Abstract:Taking account of earth oblateness and atmospheric drag, this article established the relative orbital dynamics for electromagnetic formation flying. The model of electromagnetic force is derived by the dipole approximation of the coils, and the relative orbital dynamics of EMFF is derived by Hill equation. Utilizing the linearization of electromagnetic force between any two satellites, atmospheric drag and earth oblateness, the linear relative orbital dynamics is presented. The results indicate that the linear relative orbital dynamics is reasonable and feasible. Compared to the nonlinear dynamics, the error of 3 revolution is about 0.05 m~5 m, which is resulted from the linearization of electromagnetic force. 

Abstract:In order to study the frequency cracking caused by the nonuniform of density distribution, the dynamics equations of resonator under the nonuniform of density distribution were established by way of Bubonov—Galerkin method which is common used for solution of differential equations, the state equation was established by the dynamics equations, and then the system characteristic equations were derived. According to the system characteristic equations, two second order natural frequency caused by the density nonuniformity around the hemispherical of vibration system and the expression of frequency cracking were solved.

Abstract:To better understand the properties of gravity field of irregularly shaped asteroid, this paper adopted the Polyhedron modeling method to calculate the gravity filed of asteroid Eros433, and analyzed the distributing properties of this asteroid’s gravity field. Firstly this article introduced the concept of Polyhedron model and the method of calculating polyhedron model of asteroid, and then the polyhedron model of asteroid Eros433 was given. After that, Gauss Law and Green’s formula are applied to the calculation, and by twice integral transformation the triple integral of gravitational potential function can be transformed into single integral, which can be used in polyhedron model to derive the formulas of gravitational potential function, gravitational acceleration and Laplacian. Finally, the formulas derived were applied to calculate and analyze the distributing properties of gravity field of Eros433, after taking the self-rotation of asteroid into consideration, Pseudo-potential surface and Zero velocity curve are used to analyze the orbital dynamic environment around the asteroid and the position conditions of equilibrium points of asteroid.

Abstract:To improve the on board data handling ability, an on-board electronic system required further optimization. On the basis of present reconfigurable on-board computer design, the paper introduced a concept of multiple core processors. According to the functions of the data handling and limitation of the hardware resource, the tasks implemented by single processor are divided into two parts taken by dual-processors. Compared with on-board computer employed on SY-3, multiple core processors have surmounted the peers in computation speed and calculation accuracy. The result verifies that multiple processors will play an important role in future spacecraft designs.

Abstract:A micro mechanical model was established to analyze the longitudinal Young’ modulus and transverse shear modulus of the fiber composite columns reinforced foam core by using Corrected Mori-Tanaka theory. The test results show that the prediction results of the longitudinal Young’ modulus and transverse shear modulus of the composite structure was effective. And then the effect of the fiber composite column parameters was evaluated. Results indicate that the volume fraction in the fiber composite columns has great influence on longitudinal Young’ modulus, but has little influence on the transverse shear modulus. The specific longitudinal Young’s modulus increases with the increase of diameter of fiber composite columns, but the specific transverse shear modulus decreases with the increase diameter of fiber composite columns.

Abstract:To deal with the problems of limited samples, high dimension and non-linear in hyperspectral imagery classification, two new techniques, support vector machine (SVM) and relevance vector machine (RVM), are researched in this paper. Similarities and differences are compared and analyzed between SVM and RVM in hyperspectral imagery classification theoretically and experimentally. By simulations and experiments on classification accuracy, computational cost and sparsity, the results show that RVM model is sparser compared with SVM, which makes its test time much shorter, and thus more suitable for online testing of large amount of hyperspectral data. However, the main drawback of RVM is that its classification accuracy is slightly lower than that of SVM. To improve this performance, Fisher linear discriminant analysis (FLDA) is utilized before classification as a pre-processing to make transformation of hyperspectral data. In this way, not only the dimension of image is reduced, but also the classification accuracy of RVM is improved, especially in small land-cover patches, which makes the application of RVM more widely.

Abstract:To compare the effectiveness of three methods to extract the information of 3d surface roughness of particle reinforced aluminum matrix composites, specimens was high-speed milled, and the surface micro-topography was measured by OLS 3000 microscope. The least squares method, Gaussian filtering method and extensional Gaussian filtering method were adopted to extract the information of 3d surface roughness and 3d roughness parameters were computed. Gaussian filtering and extensional Gaussian filtering method are sensitive to the defect, also the information extracted is unstable. The least squares method is appropriate for this material because of the retention of the defect’s information and the high stability. 

Abstract:To design a better output performance radial piston motor with inner curve, a new-type inner curve which is named modified heart-shaped curve is presented. The curve is simple, continuous, closed and higher-order differentiable. Using this curve as an inner curve of radial piston motor, the internal impact problem is solved. The influence of the piston’s number and periodicity to the phase position are analyzed. The result shows that the motor’s pulsation rate depends on the equivalent number of piston. A general formula for the pulsation rate of the motor with the modified heart-shaped curve as an inner curve is derived, and the formula shows that the motor’s pulsation rate decreases with the increase of the equivalent piston number. At last, the conclusions are certified by simulation.

Abstract:Aiming at the problem that the edge features of vibration parameter images for rotating machinery are difficult to be extracted, the filtering enhancement processing method and the self-adaptive edge detection operator are established according to fuzzy soft morphology theory. The 3d vibration parameter images of rotor's normal state, fault of unbalance, misalignment, steam exciting vibration and bearing pedestal looseness were obtained from the experiments on the modeling of 600 MW turbine rotor experimental bench. These 3d images were transformed to 2d gray-scale images, and these 2d gray-scale images are processed with fuzzy soft morphology filtering enhancement processing and self-adaptive edge detection. The results show that with this method the noise of parameter images can be filtered out and the edge features of images can be extracted effectively, so that a new method to extract image features for rotating machinery fault diagnosis is provided.

Abstract:To make use of available system resources and obtain higher reliability optimum, a heuristic greedy replication algorithm is designed. This algorithm is based on the increased reliability optimum of each unit's bandwidth OB and memory OM. It uses the greedy idea to select two sets of software components that may be replicated. The software components of the set with higher reliability optimum are selected to replicate by the algorithm. Given the limited available system resource, comparing with greedy replication algorithm, this algorithm can obtain higher reliability optimum and higher service reliabilities. Therefore, when the available system resource is constrained, the heuristic greedy replication algorithm is a good method of selecting software components to replicate.

Abstract:In order to render large scale ocean waves in real-time, an effective method is presented. Firstly, a novel geometry model based on LOD (Level of Detail) is used as the ocean surface, and the Gerstner wave is applied on GPU to simulate dynamic ocean wave and choppy wave. A bump mapping texture is utilized on areas far from the eyes for improving rendering performance, and the animated bump mapping textures are used to enhance the rendering effect of ocean surface. Secondly, the sun and sky reflections are achieved via cube mapping texture. Phong light and Fresnel reflection are discussed and applied. Special effects such as cloud shadow and whitecaps based on texture animation are implemented. Experimental results show that the method can be used to render a 90 km ocean scene interactively in real-time and has been applied to a flight simulator successfully.

Abstract:Quantitative analysis and mining of product reviews posted by users are helpful for both manufacturers and consumers. During the work of fine-granularity product review mining, extracting feature-opinion pair is one of the core works. The corresponding corpus construction is of great significance for the application of high performance machine learning methods, improving the performance of feature-opinion extraction algorithm and automatic evaluation. This article introduces corpus constructing technology for fine-granularity product review mining and the initial corpus labeling work, thus realizing non-structured to structural changes. The corpus can be stored in database and thus provide great convenience for automatic query processing. Although current labeling work was performed in mobile phone products, it can be applied also to other product types for fine granularity corpus construction. So our work has good transplantation ability. 

Abstract:During the micro wire electrical discharge machining (MWEDM), the micro wire electrode will deform under all kinds of force. A finite element analysis approach is presented for calculating the wire electrode deform. At first, the wire’s stiffness matrix only by wire tension and that only by spark force were obtained independently, and then the total stiffness matrix and the wire max deform analytic expression were got and the influential factors were analyzed. The results show that the wire deformation can be reduced by increasing the wire tension and the wire rigidity, and decreasing the span between the guide pulleys, while providing the micro energy pulse power is the best choice.

Abstract:To solve the problem of target polarization loss and phase distortation of conventional three-dimension polarization filter for High Frequency Surface Wave Radar (HFSWR), a three-dimension polarization filter approach based on oblique projection is proposed in this paper. The spatial polarization parameters of the target signal and interference signal are used to span the corresponding subspace respectively, and then an oblique projection operator is obtained to form a polarization filter vector. Compared with the conventional three dimensions polarization filter, no amplitude loss and phase distortion of the target signals are introduced while the interference is mitigated perfectly, the improvement of significant signal to interference plus noise power ratio (SINR) can be expected and the phase coherence of the target signal can be kept. The simulation results indicate that the proposed method can effectively suppress the polarized interference for HFSWR.

Abstract:For the accuracy of indoor location system based on the strength of received signal being restricted by the multipath effect and non line of sight propagation,a location algorithm using radio frequency identification was proposed which was suitable for 915 MHZ UHF signal. Dual frequency subcarriers were introduced to overcome the ambiguity of whole cycles and reduce the demands of sample rate. On the basis of spectrum analysis of All-Phase FFT, a mechanism was put forward to estimate the phase difference so as to achieve the ranging information with under-sampling, and then the position of the tracking tags could be obtained by the least square method. Simulation results show that, the proposed algorithm possesses a higher accuracy and stability.

Abstract:To reduce the influence of current allocation strategy of monitoring points for control system of process quality and the influence of error propagation of quality indicators among processes, a decision-making model of quality monitoring and control for a multi-stage manufacturing process based on dynamic programming method is built up. The example analysis proves the validity of the model, and the results show that the model will benefit for monitoring and control and make the strategy formulation more reasonable.

Abstract:Simulations on three kinds of working conditions (heating, cooling and radiation) and different kinds of air-inlet and air-outlet patterns to gain the corresponding distribution of air velocity and temperature inside the shelter were done with FLUENT software. The results indicated that: the cabin average temperature rose from 243 K to 290 K after 300 s when heated; the temperature reduced from 343 K to 302 K after 300 s when cooling; the temperature reduced from 343 K to 302 K after 264 s when considering the effect of radiation during the course of cooling. The results also indicated that: the average air velocity of left-in and left-out pattern was the biggest in the upper space of shelter, while it was the biggest in the lower space of shelter by choosing the right-in and right-out pattern; ventilating effect of complicated air-inlet pattern was better than that of simple air-inlet pattern, and the front-direction removal pattern was better than the down-direction removal pattern. 

Abstract:To improve vehicle ride comfort and handling stability, a multi-objective optimization strategy based on improved genetic algorithm was designed for the suspension system. As the study of a light passenger bus, taken the vehicle body side angle, yaw rate and the amplitude of vibration acceleration as optimization index, a multi-objective optimization model of suspension system parameters was established. The method improved the selection mechanism in the individual populations, and the improvements would enable the parent population and offspring population of optimal individuals to have the same opportunity to be selected to ensure diversity of new species. The real vehicle experimental results showed that: compared with the suspension before optimization, the vehicle body side angle, yaw rate and the amplitude of vibration acceleration had been reduced by 12.3%, 6.4% and 9.8%. The new strategy could reasonably match the parameters of suspension system, and simultaneously improve the vehicle ride comfort and handling stability.

Abstract:Three-dimensional (3D) model reconstruction needs to resolve the association problem of precursory 3D process model and process drawing. An approach based on the attribute adjacency graph of the primitive combination units is proposed. By extracting the primitive combination units of process drawing and the projection drawings of the precursory 3D process model, the process drawing and the projection drawings was presented in an attribute adjacency graph. According to the attributes of the vertexes and edges, whether the two attribute adjacency graphs were isomorphism were judged, and the association problem of precursory 3D process model and process drawing was translated to the matching problem of attribute adjacency graphs. Taking the side plate part as an example, the experimental result shows that this method realizes the association of precursory 3D process model and process drawing.

Abstract:In this paper, an information fusion method based on fuzzy set and evidence theory was proposed. Firstly, the fuzzy membership function of the recognition framework was obtained from the uncertain observation collected by the sensor. Then by using the membership function, the mass function could be obtained. After that, the evidence distance was used to determine the credibility and the discounting factor of each sensor. The present approach was tested in a target recognition system to illustrate its efficiency. The simulation results show that even if the evidences are conflict with each other in a high degree, correct results can be obtained.

Abstract:To solve the problems of network management and security monitoring and auditing in trusted network, by researching the framework of trusted network connect (TNC) and the architecture of cyberspace situational awareness (CSA), in view of the certain and uncertain characteristics of multi-source information in trusted network security, a new security situational awareness and forecast based on set pair analysis (SPA) called SPSAF is proposed. SPSAF audited network connection information, system management information, system monitoring information and application service information by the method based on feature base. The security situational indexes were extracted by the method of improved entropy method (EM) and analytic hierarchy process (AHP). The SPA method was utilized to assess these indexes to get the value of network security situation, and the security-situation-graph of network was drawn. The time series of the assessment results was analyzed via the Box-Jenkin model to forecast the network security trend. The simulation experiment results show that SPSAF is accurate and effective to reflect the network security situation and its trend, which can help the administrator to make security policies efficiently, to discover risks timely, to adjust policies and take relevant protective or emergency measures quickly and accurately, and to ensure overall and reliable security.

Abstract:To overcome the problems that there are unsafe loopholes, functional duplication in TCG authorization protocols, a new trusted computing authorization protocol is proposed in the paper, in which the session key is introduced in the new protocol generated by Diffie_Hellman algorithm to guarantee its confidentiality. The new protocol can provide the function of anti-replay attack and can be applied to multiple entities. It can also guarantee the communication integrity and confidentiality of data effectively. The security properties are analyzed and verified by BAN logic in the paper.

Abstract:A lossless compression method for 3-D color images is proposed based on Improved Integer Karhunen-Loeve Transform(IIntKLT), incorporated with SPECK for color image compression. First, the IIntKLT is applied to reduce the redundancies between the color components, so that the complete reversible transform is guaranteed, and then by using SPECK, the performance of coding is improved. The results of experimentation of standard testing color image, show that the new approach has an increase of 0.1 bpp in lossless image compression, and in the case of complete reversible lossy compression, compared with JPEG2000, it at most has a increase of 0.88 dB.

Abstract:To improve the performance of AES on FPGA, an idea of fully pipeline is proposed. After analyzing the needs of memory and logic elements deeply and finding out the factors restricting the efficiency of data blocks, the high-speed operation of the pipeline node model with dual channel mold is found to implement the AES full line. Experimental results show that the throughput of the AES encryption and decryption algorithm on FPGA of EP4CE40F29C8, can reach up to 7.2 Gbps. In the framework of fully pipeline, the idea of dual channel mold makes all the pipeline data blocks in efficient working condition. System under the premise of low-cost achieves a substantial improvement in performance. 

Abstract:To examine the integration capability of candidate schemes under the condition of uncertainty, the probability multiple-criteria decision-making (MCDM) method, which is based on interval number analytic hierarchy process (AHP) and the robust design (RD), has been introduced to the effectiveness evaluation of aircraft conceptual/preliminary scheme, and the evaluation method of the Efficiency Practicability of Aircraft Conceptual/Preliminary Scheme (EPACS) has been founded. At first, the basic definition and correlative mathematics model of EPACS was made up. And then, taking into account of the correlation of all design/state variables in aircraft scheme, the structural model and the evaluation flow of EPACS was established. At last, the feasibility and validity of the above analysis had been proved by some examples.

Abstract:In spaceborne SAR (Synthetic Aperture Radar), the pulse compression of LFM (Linear Frequency Modulated) signal would be affected by the system phase error which changes in the space environment. Therefore a method of in-orbit phase pre-distortion for LFM signal based on polynomial fitting is put forward, in which the system phase error is obtained by in-orbit calibration, the phase compensation parameters are obtained by polynomial fitting on ground, and by uploading phase compensation parameters, LFM signal with compensation phase is generated by in-orbit calculation. The basis of the theory is described, as well as the realizing flow of the method is presented. Also, hardware requirements and advantages of the method are analyzed. The method is compared with other methods, and is verified to be efficient by the simulation and experiments in real system.

Abstract:The factor of equipartition of entransy dissipation was defined at first, and then, applying three-dimensional CFD software-ANSYS CFX, the double chevron-type plate heat exchangers (DCPHE) were simulated, and the entransy loss rate, the exergy loss rate and the equipartition of entransy dissipation (EoED) of the working fluid in DCPHE with five corrugation angles were investigated. Results from numerical simulations showed that the exergy loss rate of the working fluid in DCPHE with β=30° were lower than those under same mass flow conditions; the entransy loss rate of the working fluid in DCPHE with β=30° were lower than those under same amount of heat conditions; the factor of EoED of the working fluid in DCPHE with β=30° were more than those under same number of transfer units (NTU) and effectiveness conditions.