Abstract:Based on the finite volume method (FVM), OC-TVD scheme and Runge-Kutta method, parallel numerical simulation of the flow field around the hypersonic/supersonic vehicle was performed on a super computer. The parallel computation efficiency was tested with the CPU nodes varied form 2 to 64. The program was tested for its parallel efficiency on the super computer and was applied to the calculation of the flow field around space shuttle. In this way, the large-scale parallel calculating capacity of the program was examined. The results indicate that, given that the load is balanced, the parallel computation on the super computer reaches super-linear speedup. The maximum efficiency ratio reaches 126%, which is far larger than the value on PC cluster parallel platform.

Abstract:All speeds control equations were deduced from traditional compressible equations with precondition method and applied to 2D inviscous/viscous flows at all speeds. Jameson central difference scheme, LU-SGS implicit iterative method and round-off control were used to accelerate convergence rates and improve numerical precision. Computations were carried out in the bump flow in a channel, viscous cavity flow and chemical non-equilibrium flow. Numerical results were compared with standard cases. The methods and programs proved to be precise and credible. All these will serve as foundations for further study of integrated flow in combustor and nozzle.

Abstract:On the basis of direct-connect scramjet test system simulating flight Mach number 4, different injection modes were compared to study the influence of flame stability on fixed geometry dual-mode scramjet combustor fueled with liquid kerosene and ignited with torch-model ignition. It is indicated that the flame is difficult to stabilize in the flow condition of lower total pressure and total temperature. It is also indicated that the flame stability in dual-mode scramjet combustor is greatly influenced by the injection mode of kerosene.

Abstract:Laser propulsion is an advanced technology with the prospect of wide application. In this paper the main performance parameters of laser propulsion engine was analyzed. Such problems as the optimum specific impulse, the average laser power and the energy consumption of electric current for launching in 2D plane without air drag were addressed. The results show that higher mass ratio can be obtained by utilizing laser propulsion technology while the optimum specific impulse is 12240m/s.

Abstract:The interfacial debonded cracks are liable to occur in the stress relief boot of solid missile motor. In order to determine the allowable debonded depth in different storage period, a method to analyze the stability of the interfacial crack is presented. Under the circumstance of internal pressure and axial acceleration loading, the three-dimension finite element models of the motor grain with interfacial debonded cracks were established, and several interfacial debonded cracks were preset along the stress relief boot between cladding and propellant. Thus three-dimension singular crack elements at the tips of fore and rear stress relief boot were established to simulate the debond propagation. Along with the interfacial debonded crack propagation, the stress intensity factors of the crack tips in different storage period were respectively calculated to prejudge its stability. The method and conclusions will be helpful in using solid missile motor with interfacial debonded cracks.

Abstract:The purpose of this paper is to study the type optimization of small satellite major joint, which is based on static and buckling analysis of honeycomb sandwich plates. Firstly the 3-D FEM model of honeycomb sandwich plates was established by the sandwich plate theory, in which the fork-form or faceplate major joint was buried beforehand. After the liner static and buckling analysis, the maximal Von-Mises stress and buckling load were obtained. Compared with the result of experiment, the failure causation to the Honeycomb Sandwich Plates was then determined. Finally the influence of the structural parameters upon load capacity was discussed, and the optimum major joint type was ascertained.

Abstract:The formation process of shaped charge jet was analyzed and the models of all the phases in the formation process were proposed. The detonation of explosive, the interaction of the explosive with the metal liner, the collapse of the liner, and the formation of the jet and slug were taken into account in the models. A calculation of a specified shaped charge was conducted on the basis of the model, and the results conformed to the data from experiment. It shows that the collapse velocity of the peak and the bottom of liner is smaller than that of the middle of liner and therefore the reverse velocity gradient is formed. It can be concluded that the models can be used in the engineering design of MWS and the calculation of penetration parameters.

Abstract:C/SiC composites were manufactured by the process of reactive infiltration of gaseous silicon with carbon felt reinforced carbon green, which is made from viscose rayon-based carbon felt perform treated with CVD carbon and phenolic resin pyrolysis carbon. Effects of re-impregnation and pyrolysis cycles of resin on the density and porosities of green and the micrograph and mechanical properties of C/SiC were studied. The result indicates that with the increase of re-impregnation cycles and the density of green, the porosities of green declines. The bending strength and modulus of C/SiC reach the maximal figures, respectively 231MPa and 209GPa when the pyrolysis carbon content of preform is set to 27wt%. The mechanical and microstructure properties of C/SiC can be tailored by controlling the pyrolysis carbon volume in the green.

Abstract:A novel core-shell type branched macromolecule was synthesized from the tris(hydroxymethyl) aminomethane(Tris) and the monomethoxypoly(ethylene glycol)(mPEG). The first step was to protect the amino group of Tris by using t-butyloxycarbonyl anhydride ((Boc)2O), then mPEG was activated by changing hydroxide terminal into acid chloride and carboxylation of mPEG was fulfilled before. The amino group was reserved so that it could be used as functional radical to modify the protein later. The product was confirmed to inosculate with FT-IR, EA and M.W. through infrared spectroscopic analysis, element analysis and mensuration of molecular weight.

Abstract:After analyzing the background of cluster routers, this paper proposes two cluster routing reference models: Software-based Cluster Router Reference Model (SCR-RM) and Parallel Cluster Routing Reference Model (PCR-RM). The detailed description of the two models is also made. These models will provide reference systems, experiment systems and IP flow processing scenarios for future studies.

Abstract:After analyzing the background of open network architecture, the paper proposes an OpenRouter model. The model consists of 4 logic layers, between which there are 3 standard APIs to separate the router into variant modular functions. Based on the OpenRouter model, an IPv6 router system is implemented and the key points of implementation are described within the paper.

Abstract:With the rapid development of the Internet, for the benefit of improving the using rate of the entire network resources, the technique of inter-domain traffic engineering was proposed for the performance optimization of traffic that originates in one administrative domain and terminates in a different one. Based on the analysis and evaluation of current researches on the architecture of inter-domain traffic engineering, the RCP architecture for inter-domain traffic engineering was suggested. Finally, some main key problems were discussed for future researches.

Abstract:This paper presents a new mechanism called BGP(border gateway protocol) with ATS (advertisement time stamp), which can greatly reduce routing convergence delay for BGP greatly. In the approach presented, when a BGP speaker sends a peer an advertisement packet, it marks the corresponding routing prefix/prefixes with the system time. When the next advertisement packet is ready, the BGP speaker decides whether the packet should be sent immediately or not via the corresponding time stamp checking. It shows that ATS takes advantage of the per-peer MRAI(min-route-advertisement-interval) Timer and per-peer per-destination MRAI Timer while overcoming their disadvantages. Theoretical analysis demonstrates that ATS can achieve a dramatic improvement in routing convergence for Tup, Tshort and Tlong events in comparison with BGP and other existing solutions.

Abstract:Maximizing the collective functional lifetime is clearly one of the biggest design objectives of any wireless sensor network. For this purpose, it is important to find out the value of maximum lifetime of a sensor network exactly. In this paper, the lifetime maximization was formalized for the multi-source multi-sink maximum flow problem of a directed graph with arc and vertex capacity powers. Then a method was proposed to solve this kind of maximum flow problem.

Abstract:The number and the quality of the paths dictate the performance of a multipath routing scheme, a problem which has not been sufficiently dealt with before. With an analysis of two current problems and a discussion of the routing reliability model and the virtual non-crossing multiple path routing model, a pathset selection algorithm called Maximal Reliability Pathset Selection for Multipath Routing is proposed in this paper, which selects the pathset according to the reliability of the paths and distributes traffic into multiple paths to optimize bandwidth usage and improve the throughput. By implementing this algorithm on the OPNET environment, the result shows that the scheme can balance the network load and improve the stability and reliability with minimal additional exchange overhead and with minimal additional storage requirements. Therefore it can be beneficial for mobile ad hoc networks.

Abstract:The behaviors of the Inter-domain Routing (IDR) System are becoming rather complicated with the rapid development of the Internet. Security incidents in IDR system have attracted extensive attention among people. This paper proposes a rule-based monitoring framework to secure IDR System, in which the rules can be used to effectively detect anomalous routes and possible attacks. Unlike GADRs, SADRs were defined according to some Internet models that are behavior-models represented by large numbers of normal routes. Furthermore the construction of the Internet Hierarchy Model and ISP Commercial Relationships Model were studied, and methods based on these models were developed to detect hidden route anomalies or attacks. ISP-Health, the prototype of such a monitoring system supported by the above-mentioned framework, was implemented, and its capabilities were exhibited at last.

Abstract:With the Internet continuing its expansion in range and its increase of linking density, the BGP routing protocol, which works as the inter-domain route standard, has met serious challenge. The emergence of clustered router, which has the advantages of distributed storage, computation resources and high extensibility in system and structure, is helpful for people to meet the challenges. Considering that BGP protocol architecture is not suitable for clustered router, this paper proposes a new distributed BGP architecture, which can take advantage of distributed resources of clustered router greatly. Compared with traditional BGP architecture, the distributed BGP architecture can improve protocol reliability, lower administration costs, simplify BGP network topology and improve BGP scalability.

Abstract:Task allocation is one of the core steps to effectively exploit the capabilities of cooperative control of multi-UCAV. Factors that effect the three key tactical objects, target value damage, UCAV attritions and task expending time are analyzed. By integrating the two typical instances in combat, that is multi-UCAV attacking the same target simultaneously and using soft kill weapon systems, a multi-UCAV cooperation task allocation model for attacking task is formulated. A new algorithm based on the principles of particle swarm optimization is proposed. Simulation results indicate that the task allocation model formulated in this paper is rational and the PSO based algorithm is effective.

Abstract:Based on interferometry measurement theory of satellite carrier phase, the technology of land vehicle heading determination through Beidou Bi-Satellite System was studied. Firstly the mathematical model of Beidou heading determination was set up. Then the ERMM (Equivalent Rotating Maximum/Minimum) ambiguity resolution method based on antenna swap thoughts was discussed. Vehicle real-time heading resolution experiments were designed by using a two-antenna pointing system, and the heading precision was verified through a vehicular RLG (Ring Laser Gyro) strap-down INS with high attitude accuracy. The test results confirmed the effectiveness of ERMM ambiguity resolution method with the real-time heading determination accuracy reaching 0.62 degree. The research indicates that Beidou Bi-Satellite System can be used to real-time land vehicle heading resolution.

Abstract:Due to the short streamline nose, the aerodynamic performance of Shanghai maglev train is not very good. In this paper, several streamline shapes were designed for domestic maglev train according to the given section and requirements supplied by domestic rolling stock works. By using the three-dimensional compressible N-S equations and turbulence model, aerodynamic performances of all schemes were analyzed, and then the streamline shapes were optimized based on the calculation results. In so doing, the best streamline shape with good aerodynamic performance and good appearance were obtained. Because of the narrowest horizontal contour line and the smallest curvature of vertical contour line, the aerodynamic drag force and train passing pressure pulse of the third scheme are the least among the final three selected schemes, so it is the best. The results show that this streamline shape designed for domestic maglev train is better than Shanghai maglev train (TR08) in aerodynamic performance, and the aerodynamic drag force of domestic maglev train is 33.84KN at the speed of 4300 km/h, while TR08 is 54.07KN; at the same time, the train passing pressure pulse of domestic maglev train is 2913Pa, while TR08 is 3827Pa.

Abstract:This paper studies the undulation control on the bionic device of long flexible fin based on undulation movement generated by the long flexible fin of Gymnarchus niloticus. Firstly, the principle of forming propulsion wave and the realization scheme of long flexible fin were studied. Secondly, a kinematics model was established to describe the undulation surfaces of the bionic device, the undulation control parameters which can be used in realizing multiple undulation modes of bionic object were distilled, and the methods of realizing some given undulation modes of long flexible fin were studied by simulations. According to the physical constraints of the bionic device, the criteria to judge the validity of these parameters were also presented. Finally, the paper studies undulation control strategy and control-flow of the bionic device of long flexible fin.The research result indicates that the bionic device of long flexible fin can imitate multiple undulation modes of bionic object via setting control parameters properly, and can realize multi-parameter control of propulsion wave. So, it can satisfy the unsteady hydrodynamic measurement demands of the bionic device with multiple undulation parameters.

Abstract:This paper presents a numerical method to compute CAD surface models. The method first divided a CAD model into a sequence of subfields, each of which is a simple surface-patch of the CAD model. Then, by setting up the governing equations for the patch-element, it computed the total field by assembling governing equations of all subfields into the global equations of the total field according to the manifold structure of the CAD model. The element's governing equations can be formed by coupling finite element (FE) with boundary element (BE), and FE with element free (EF) or else according to the objective of the computed problems. The paper systematically demonstrates the key procedures of selecting elements and setting up governing equations via a solution process of linear elastic problems. A numerical example with comparison to ANSYS computation is shown in the analysis of deformation on a blending surface of three-rounded corner. Finally the static loads are presented before the paper comes to an end.

Abstract:To detect faults of a liquid rocket engine (LRE) turbopump effectively, a turbopump fault detection approach based on rotor intrinsic frequency is presented in this paper. First of all, 28 LRE historical test data were analyzed, from which the values of the first, second and third order critical frequency and the axial intrinsic frequency were achieved. After that, the stability and turbopump fault sensitivity of this four rotor intrinsic frequencies were researched, from which we found that their intrinsic frequency amplitudes had high stability and fault sensitivity. Finally, the turbopump fault detection approach was validated by LRE historical test data. The results show that the turbopump faults can be detected effectively by using the amplitudes of rotor first, second and third order critical frequency as well as axial intrinsic frequency.

Abstract:The immune clone evolutionary (ICE) algorithm is presented to optimize the parameters of the fuzzy neural network (FNN) controller for the complex billet heating process. First, the neural model of the process was set up via the observation data; then, based on the model, the rule optimization algorithm of the fuzzy neural network controller (FNNC) was introduced to obtain the optimal rule numbers of the FNNC. Finally, by combining the FNNC parameters obtained with the rule optimization into an individual in the initial population, the ICE algorithm was adopted to optimize the parameters of the FNNC. The proposed search strategy is a global optimization and local precision optimization algorithm. Results from simulations prove the effectiveness of the constructed system.

Abstract:The present paper deals with the long time behavior of semilinear parabolic equations with time delays in the non-self adjoint case. Under the condition of right spectral gap and the assumption of properly small delay time, the existence of inertial manifolds is proved by Lyapunov-Perron method.

Abstract:Dynamic weapon target assignment (WTA) is an important theoretical problem for military operation research and a challenging practical concern in the process of combat command. Based on the description and analysis of dynamic WTA problem, the Markov characteristic of the WTA problem was proved with stochastic theory, and the transition possibility matrix of the Markov decision process was also presented. Meanwhile, the characteristic of the transition probability matrix was analyzed. The result of the research sheds light on the study on the WTA problem in theory and method.

Abstract:Using degradation measurement of product performance over time to analyze product reliability is an effective approach for high-reliability or long-life products. Based on the performance degradation mechanism of aerospace product and the small sampling characteristic of field test, a model in terms of Normal-Poisson process is proposed. Then the calculation formula for parameter and reliability evaluation is presented through the small sampling test combined with Bayes method. Finally, an example is given to show the validity of this method.