Abstract:In this paper, a novel SEU/SET hardened PFD is proposed in order to reduce the SEE sensitivity of traditional D flip-flop type PFD. SPICE simulation shows that this structure has very high accuracy. Compared with traditional PFD, the electrical properties of PLL with radiation harden PFD are not changed. Compared with the number of hit nodes which can cause PLL jitter both for D flip-flop type PFD and radiation harden PFD, the number of sensitive nodes is reduced by 80%, indicating that the anti-radiation of the proposed PFD is quite effective.

Abstract:YHFT-DX is a high performance DSP designed by national university of defense technology. This paper focuses on improving Cache performance, investigates optimization methods to reduce Cache miss stall penalties, designs and implements an optimization method focusing on one level data Cache controller in high frequency and high performance DSP-miss pipelining. Compared with traditional optimization methods, this method can deal with continual cache misses in pipeline, which overlaps multi Cache miss stalls, and then it can achieve the goal of reducing Cache miss stall penalties. Applying the method to the design and optimization in one level data Cache controller in YHFT-DX DSP, the Cache miss stall is reduced from 8 cycles to 2 cycles, and the system performance is evidently improved.

Abstract:Applying the radiation-hardened-by-design (RHBD) technique to improve the bias generator and the ring oscillator of the differential voltage-controlled oscillator (VCO) with symmetrical loads, a single-event transient (SET) hardened VCO was designed and implemented in 0.18 μm CMOS process based on the failure mechanisms. Simulation results indicate that the single-event susceptibility of the VCO is significantly reduced. Simultaneously, it also reduces the jitter sensitivity to supply noise. This new VCO topology results in a decrease in the frequency, but it can be figured out by adjusting the sizes of the delay buffer. Furthermore, the radiation hardened VCO leads to a decreased area requirement.

Abstract:Dynamic and differential logic styles are proposed as a typical differential power analysis (DPA) resistant technology. Because of the constant transition rate of dynamic and differential logic gates, the correlation between power consumption and signal values is significantly reduced. In this paper, a novel look-up-table (LUT) based differential logic (LBDL) and the design method based on this logic are presented. Instead of a full custom design, this method combines some modification with a regular standard cell design flow. Thus, have a better practicability. Unlike WDDL (Wave Dynamic Differential Logic), which can also be implemented by standard cell design flow, the transition time of LBDL gates is independent of input values, hence power consumption of LBDL is more constant. Experimental results indicate that the LBDL-based design method can eliminates most of the power leakage.

Abstract:The single electron transistor (SET) has become one of the most promising components in nanometer electronic functional devices because of its advantages of low power consumption, high speed and high integration. But due to the special features in structure, SET usually operates only in very low temperature, which prevents SET from being feasible devices. Therefore, it is very important to investigate SET which operates in room-temperature. In this paper, based on the analysis of working mechanism of SET, we calculate the conditions in which SET can operate in room-temperature, then prepare SET samples in laboratory. The measurement results show that the prepared SET can operate normally in room-temperature. The research findings will deliver a fine foundation for the practical application of SET.

Abstract:In multi-voltage island SoC, power management is one of the most important fields. The current of workload is the firsthand information of power dissipation, so, the current sampling is the first step in the cycle for high accuracy real-time power management. In this paper, we presented a kind of high accuracy current sampling technology. The circuit is based on current mirrors without operation amplifier, and the voltage of power supply can be ultra low. We designed this circuit with 0.18μm CMOS process. It is shown that the accuracy of this circuit can be 99.1% according to the Hspice simulation and power consumption is less than 4mW for workload in 60～1300mA.

Abstract:Various sub-pixel interpolation technologies are adopted in video coding applications. A multi-standard configuration interpolation architecture is proposed. It consists of two independent 8-tap filters. It can also reduce about 46% interpolation computation by a two-step filter method. Each filter includes a filter parameter register, which stores different filter parameter for various video standards. As a pipeline architecture, filter can have three filter results in one cycle. In SMIC 0.13μm CMOS process, the frequency of this architecture is up to 400MHz, and the area is about 32.6k gates. The experiment results show that, working on 250MHz, this architecture can satisfy the interpolation computation requirements of encoding 1920×1080,30fps HD video sequences.

Abstract:Conventional diffuser is introduced briefly and its mechanism is analyzed. Full Navier-Stokes equations based on low magnetic Reynolds number assumption with Favre weighted average mass are used to simulate the flow field in supersonic diffuser with added electric and magnetic field. Compared with conventional diffuser, it is obvious to see that the deceleration and expansion are realized in shorter distance when proper electric and magnetic field added, and part of the kinetic energy is transformed into electric energy. Study shows that the positions of the first shock wave, and the second shock wave and the length of shock train in the diffuser when certain magnetic field added are respectively 62.19%, 77.74% and 50.18% to the ones of conventional diffuser.

Abstract:On-orbit capture by space robots is one of the main modes of spacecraft on-orbit servicing. For space robots capture of uncontrolled rotating satellites, the 6-DOF synchronization control approach strategy is investigated to improve the time horizon to suit grasp. Firstly, the target motion model is provided, and the attitude is described by modified rodrigues parameters. Then suppose that the attitude control of space robot is actuated by momentum wheels, the 6-DOF synchronization control is conducted in two phases: translational control and rotational control. In consideration of the uncertainty in inertia parameters, the control laws for translational and rotational synchronization are derived respectively by adaptive output feedback control. The simulation results show that the models and algorithms are efficient under the condition of unknown bounded disturbances and inertia parameters uncertainty.

Abstract:The orbital reconfiguring problem after maneuver failure for rendezvous phasing is studied. The orbital reconfiguring design rules are proposed and four types of orbital reconfiguring plan are provided respectively for every maneuver failure in five-impulse phasing mission. Based on the proposed design rules, the provided reconfiguring plan's correcting ability, tracking and command condition, propellant consumed, terminal precision and security are analyzed. Finally, the orbital counter plan to deal with rendezvous phasing maneuver failure is obtained.

Abstract:The newly finished Φ200 hypersonic wind tunnel(Mach numbers 2.5 to 7) has been tested and calibrated. The results of calibration indicating total temperature, total pressure, operating time of HWT-200 have accorded with the purpose of design. HWT-200 can run within large Mach number span at supersonic/hypersonic flow. The rms of Mach numbers (σ_M) at all test sections Mach numbers from 2.5 to 7.0 reaches the requirement of GJB1179-91. A large, uniform region of flow was documented. Operational time of HWT-200 is no less than 20s. So, HWT-200 is a facility which can be used for teaching of aerodynamic experiments and elementary scientific researches.

Abstract:Considering the fact that it is difficult for the conventional PID controller to meet control request in the aircraft control process, we designed a normalized feedforward-feedback controller system. Furthermore, the hybrid optimization algorithm that combined the chaos optimization algorithm and the conjugate gradient method was used to search for the optimum parameters of the feedforward-feedback controller system. Simulation experimental results and experimental analysis proved the superiority of the hybrid optimum feedforward-feedback controller, which showed better dynamical and steady behavior, strengthened the fitness and robustness of the system, and weakened the blindness to selection of learning factors and high dependency on experience.

Abstract:In order to maximize the range of reentry, the trajectory of hypersonic glide-reentry vehicle is studied. The optimal trajectory is obtained using legendre pseudospactral method (LPM). The effect of the path constraints on the trajectory is analyzed. Furthermore, the regulation of the control variable of the constrained trajectory is analyzed. According to the rule, a piecewise linear model of the coefficient of lift is proposed. Numerical simulation shows that the trajectory derived by this model is very similar to the optimal trajectory, and the ranges of the two trajectories are nearly the same, demonstrating a good control method for the maximum-range trajectory.

Abstract:A multi-objective optimization for rest-to-rest maneuvers of flexible spacecraft is presented by using MOEA/D (Multiobjective Evolutionary Algorithm based on Decomposition). The multiobjective control design functions which deal with the minimal maneuver time and fuel consume are developed by using rigid-flexible couple dynamics model of spacecraft. A new MOEA/D approach is introduced for maneuvers problem of flexible spacecraft control system. The simulation results show that the approach can be efficiently realized in design and analysis of flexible spacecraft.

Abstract:Trajectory optimization is a key technology of hypersonic glide vehicle. In order to avoid the disadvantage of indirect method's sensitivity to initial guess and pseudospectral method's difficulty to settle path constraints, a direct method based on Akima spline interpolation is proposed to solve reentry trajectory optimization problem. A numerical example that minimizes the stagnation point heat flux and fly time to target while satisfying state constraints such as vehicle dynamics, control limitation, waypoint, no-fly zone, dynamic pressure and overload is presented. Compared with literature results, the results show that the Akima interpolation can decrease the control parameter's bound violation phenomena during interpolation; the Pareto front distributed nicely, providing more choice to designer during concept design stage. Compared with the single object optimize result in literature, the algorithm adopted in this paper also shows better performance.

Abstract:The removal function in ion beam figuring (IBF) exerts great influence on the fabrication residual error of optical surface, so that the performance of optical surface is changed because of the surface scattering induced by the fabrication residual error. In order to reduce the influence of the fabrication residual error on the optical performance, the IBF simulation procedure based on the computer controlled optical surfacing (CCOS) technique was used in surfacing the optical mirrors, and the influence of the removal function width on the ratio of scattering loss (RSL) was analyzed. It was shown that the influence of the fabrication residual error on the RSL declines with decrease of the removal function width. Thus the removal function width can be chosen reasonably according to the influence of the fabrication residual error on the RSL and the requirement of RSL index, and the processing technique can be optimized under the condition of satisfying the surface accuracy requirement of the optical mirrors.

Abstract:To realize the super-smooth polishing of chemical vapor deposition silicon carbide (CVD SiC), nano-scratch test is applied to study the critical load for brittle-ductile transition, and its polishing mechanism is analyzed according to the force on an abrasive grain. Furthermore, the influencing factors on the surface roughness are systemically investigated by experiments from the aspects of material characteristics, processing parameters and pH values of the polishing fluids. The research results show that the polishing mechanism for CVD SiC in a steady polishing process is a ductile scratch process of abrasive particles on the surface of CVD SiC. The inhomogeneity of CVD SiC grains and surface high spots degrade the surface finish. The surface roughness increases near-linearly with the abrasive particle size in a certain extent, and increases with the hardness of polishing pad. However, the effect of polishing pressure on surface roughness is related to the deformation behavior of polishing pad, i.e., when polishing pad has an elastic or elastic-plastic deformation, surface roughness increases with polishing pressure in a narrow range; when polishing pad has a plastic deformation, polishing pressure has no obvious effect on surface roughness. In addition, polishing velocity and the pH value of polishing fluid have little effect on surface roughness. The research results provide a quantitative experimental basis for the optimization of selecting processing parameters during the super-smooth polishing of CVD SiC.

Abstract:The optimization of Latin hypercube design is an important area of the space filling experimentations. The existing procedures to find optimal LHD by minimizing the pairwise correlations or maximizing the minimum inter-site distance in traditional LHD optimization are introduced, and their drawbacks are discussed in these methods. This paper proposes a multi-objective optimization approach to find optimal LHD by combining pairwise correlation and the maximin inter-site distance performance measures by modified ESE algorithm. Several examples are presented to show that the optimal designs are good in terms of both the correlation and distance criteria.

Abstract:Availability, as a scale of the reliability and maintainability level, is an important parameter of repairable system. A method of calculating system availability for series repairable system is studied in the current research. From the states of components, the methodology presented uses a gamma distribution to model the material degradation, and the impact of imperfect maintenance actions on the system reliability is investigated. At last, a numerical example is presented to demonstrate the use of the model.

Abstract:Based on finite element virtual bench test, a new method to acquire the reduced load spectrum, which is used to conduct accelerated fatigue bench test of driving axle housing, is brought up in this paper. After static strength analysis, fatigue life prediction, strain history acquisition and time correlated damage analysis, the reduced load spectrum for the accelerated fatigue bench test of a military special vehicle driving axle housing was acquired under the FE simulation circumstance. The bench test result shows that the reduced load spectrum can significantly shorten the test period, while the damage can be preserved as well, which proves the value of the method.

Abstract:To deal with the location estimation problem in many observations by the satellite-borne interferometer, this paper presents a new location integration algorithm, which is independent of any prior knowledge. First, it analyzes the location precision of the satellite-borne interferometer. On the basis of this, it presents an integration algorithm of emitter loci by using the location errors covariance matrix as weights. Simulation results show that the location precision can be improved by using the new method.

Abstract:Situation display plays an important role in the combating simulation system based on HLA, especially in reflecting the status of combating entities and assisting decision-makers to modify the combating plan. The situation display systems used in combating simulation systems have betrayed the deficiencies of low adaptability and limited scope application field. These deficiencies restrict the widespread of situation display. Military symbols mapping and the pretreatment of simulation situation data are presented to improve situation display. Then a situation display system using the key techniques is realized. Finally, the advantages and disadvantages of the key techniques in situation display are summarized and the future is expected.

Abstract:Analyzing similarity of news video stories is crucial for searching, retrieving, browsing and tracking news video stories. A method based on “scene words” is proposed for measuring the similarity of news stories. Each key frame is seen as a “word” and a news story is seen as a document which is represented by a sequence of “scene words”. In light of this, the particularity of “scene words” is investigated. An effective method to describe weight of words and calculating similarity of stories is presented. Experiment results show that the method based on “scene words” is closer to the sensory and requirement of users.

Abstract:By means of fault tree analysis method, this paper gives a systemic analysis of the relevant factors which cause the fault of bird strike aircraft，and its fault tree is also established. Through qualitative analysis, 2580 minimum cut sets can be obtained. Expert estimation method, combined with fuzzy sets theory, is adopted to assess the happening probability of the base events. The calculating of “waste landfill attracting bird”—one of the base events of bird-strike-aircraft, is given as an example of this method. Through quantitative analysis, the happening probability of the top event is 0.00241, and the importance degree of all base events can be analyzed.

Abstract:Catalogue service is an important function of battlefield environment support system oriented service architecture, and it aims to introduce the multi-source massive battlefield environment information into task oriented datasets for operators. To standardize catalogue service for battlefield environment information and realize intelligent search function, the OGC-CSW specification and ontology were introduced. The framework of the catalogue service for battlefield environment information was established, and the key techniques, such as metadata information model, task ontology model and semantic search mechanism, were researched. At last, the methods were validated by the experiment.

Abstract:The ballistic experiment of 30mm semi-AP obliquely penetrating ceramic/steel target is designed, and the image measurement method of impact angle, displacement and back plate deformation is proposed. The high-speed photography image sequences is measured based on digital image processing, and the effect of impact angle of oblique penetration is analyzed. The study shows that the impact angle will induce asymmetric effect in the projectile's penetration process, and the angle of yaw will gradually increase; under the same velocity condition, when the impact angle increases, the time of penetration will prolong, and the penetration performance will be reduced.

Abstract:The rheology and spinnability of PACS with various aluminum contents were studied by a single-pole spinning equipment. It has been shown that: the melting PACS behaves to be a near-Newton fluid with increasing temperature. The viscosity of PACS strongly depends on the temperature. Its apparent viscosity energy occurs between the range of 190～260 kJ/mol when its softening point lies between the range of 190℃～220℃. Its spinnability is good when its viscosity is about 100Pa·s. It is revealed that the higher Al content in PACS will increase the viscosity, leading to a higher spinning temperature and poorer spinnability.