Abstract:A new type of self-compensated conical hydrostatic bearing for precision rotary table was designed, manufactured and tested. The design formulas were derived based on flow equilibrium, and the optimal stiffness was obtained both from the axial and the radial directions. The effect of manufacturing error on the performance was investigated, and the stiffness and revolution accuracy was experimentally tested. Results show that the bearing stiffness is influenced by the resistance ratio between the restricting gap, the bearing gap and the inner flow coefficient between pockets; the resistance ratio has an optimal value, and a little value of the inner flow coefficient is favorable to the stiffness; the model considering manufacturing errors can effectively predict the range of the bearing stiffness. 

Abstract:Getting accurate geomagnetic field measurements on the route of the vehicle is the precondition for geomagnetic navigation. The interferential magnetic field of the vehicle would distort the outputs of the magnetometer and influence the matching precision, so it must be compensated. Based on the analysis of the characteristics of the vehicle magnetic field, a method to compensate the geomagnetic magnitude, using vector measurements, is presented. A formulation was derived according to the measurement model of vectorial magnetometer, a nonlinear evaluation method was adopted to evaluate the vehicle interferential fields parameters, and then the evaluated results were used to compensate the real- time measurements. A simulation was conducted to test the effect of the method and an experiment was performed to validate its practicability. The results show that after compensating with the presented method, the measurement error of geomagnetic field magnitude is less than 20nT, indicating that the method has high compensating precision, good convenience in use, and can compensate the interferential magnetic field of the navigation vehicle effectively.

Abstract:Space electromagnetic formation is characterized mainly by advantages of no propellant consumption, no plume contaminations, continuous reversible and synchronous controllability, and static electromagnetic formation has a broad prospect of application in such fields as optical interferometry. The stability and control issues of dynamics equilibrium are the foundation for static electromagnetic formation. This research focused on the three equilibriums of two-spacecraft aligned with radial, along-track and normal direction, developed the 6-DOF coupled nonlinear dynamic models by the Kane method, and analyzed the open-loop stability, the coupled characteristics and the control requirements for each equilibrium respectively. Finally, an LQR feedback controller was designed and verified to stabilize the equilibriums.

Abstract:Convergence rates of the original LU-SGS scheme and its modified methods were investigated and compared under hypersonic conditions, which is aimed to implement the LU-SGS algorithm efficiently for numerical simulation of complex geometries in engineering environment. Numerical results of 2D cylinder, 3D blunt cone and space shuttle show that: the viscous terms must take the implicit form for hypersonic viscous flows. the convergence rate of the BLU-SGS inner iterations is fast than that in the DP-LUR method. Jacobian matrices in the LU-SGS algorithm have a significant effect on computational work and convergence performance. for the flows without separation, fast convergence can be reached by using the exact matrix method and for the flows with large separation, numerical instability makes the exact matrix method less efficient than the diagonal method.

Abstract:Cadets recruiting plan is an essential measurement to prescribe source and quantity of officers, which is significant for the construction and development of officer. With the accumulation of recruiting plans, it is meaningful to make analysis and evaluation of them. By utilizing the clustering technique, this research analyzed recruiting plans in the past years, and provided a quantitative approach to look into the fluctuation of plans and to understand and evaluate closeness of plans with policies. Firstly, the paper summarized characteristics of recruiting plans. Secondly, it proposed a solution which utilized labeled tree to represent recruiting plan and extracted representative subtrees to participate in clustering. Finally, it used co-occurrence idea of "forming clustering cores first, classifying the plans then" to finish the clustering process. Experimental results reveal that the method can provide better clustering results and is efficient.

Abstract:According to the ubiquitous uncertainty of resource availability, a multi-objective military mission planning model with uncertain resource availability is proposed based on reasonable hypotheses. A proactive schedule method based on resource buffer was designed according to the special features and particularity of the model. In the method, the resource buffer was added into the project during the task-platform allocation in order to minimize the disadvantage of resource uncertainty; the multi-objective evolutionary algorithm NSGA-Ⅱ was adopted to calculate the Pareto Front of the problem. Finally, an example was illustrated to show the feasibility and practicability of the proposed model and method.

Abstract:Aiming at the complexities such as huge solution space and many decision-making objectives in the system of armament systems portfolio planning, an integrated decision making and optimization framework is proposed to select the models from the candidate armament systems, and to plan the development time and production quantity of the selected armament systems. By quantitatively describing and formulating the system of armament systems portfolio planning, and focusing on the NP-hard and the large-dimensional multi-objective nature firstly; a dual-objective optimization model was proposed through adopting the goal programming method; an intelligent optimization approach was developed based on the NSGA-II evolutionary computation method, in order to obtain the Pareto solutions set thirdly; the TOPSIS method was applied to acquire the compromise solution finally. A portfolio planning example on a system of intelligence, surveillance, and reconnaissance systems validated the effectiveness of the framework. When given empirical data and decision-makers preferences, the framework can get the satisfactory portfolio plan, which supports the demonstration and development for the system of armament systems.

Abstract:Means of warfare and using of the military force are always changing as technology changes. Learning from the idea of NCW, it explored the formation mechanism of the operation network, and analyzed the combat behavior of micro and macro mechanisms. Aiming at the feature of obtaining the operational effectiveness through the information superiority，it proposed the conception of the control loop and the action rhythm in the information age, which reflected the different capability of using information between the combat systems. Thus, it proposed the combat model of operational network, and the performance indicators of measuring the operational network. It designed the experiments to study the engagement process and results of the different network structures, the different attack patterns.

Abstract:In the traditional Network-on-Chip routers, packets from different directions are temporarily stored in different buffer regions, and these buffering resources are independent from each other. Under non-uniform traffic patterns, buffers in some input channel will be crammed by the coming packets quickly, while the others are still in idle state. As a result, the buffers are utilized inefficiently, and it has a negative influence on the overall network performance. In the method proposed, an adaptive buffer regulating scheme that can be used to achieve similar performance by using less buffering resources was introduced. The VLSI implementation of a router with the buffer regulating scheme was completed under 90nm CMOS process. The experimental results show that the proposed router can bring significant performance improvement and power reduction under non-uniform traffic patterns, 20.3% area saving of the proposed router and 41% power reduction of the buffers can be achieved compared to the traditional one.

Abstract:According to the characters of web news stream, an on-line news event detection (ONED) method, based on the two-stage clustering, is proposed to solve the problem of repeated matching. A novel incremental event model was established by calculating terms weighting of events directly. Two stages are involved in our method. In the first stage, the similar reports collected in a certain period were clustered into micro-clusters. In the second, the micro-clusters were matched with existed events, and then this method updated the event model. Experiment shows that the proposed method improves the efficiency and accuracy of ONED with lower complexity and less feature information loss. 

Abstract:In order to manage the trade-off between the workflow execution time and the workflow execution cost on utility grids, the task was divided into several groups by using the workflow synchronization properties, and three real-time heuristics were proposed: the bottom level based sufferage (BLSuff), the bottom level based min-min (BLMin) and the bottom level based min-max (BLMax). A metric was designed in these heuristics to optimize the execution time and the execution cost simultaneously based on the trade-off factor, and the expected finish time was set for the task trying to make most of the cost optimization space to save the workflow execution cost. The experimental results demonstrate that these heuristics can optimize the execution time and execution cost simultaneously with various trade-off factors.

Abstract:In balanced load allocation problem in complex systems like large-scale data center and P2P overlay network, the various load allocation methods is proposed. In order to achieve better balanced load index, many methods, however, are in pursuit of more and more complicated algorithms, which makes the time and algorithm complexity hard to control. Based on the study of the original balls-into-bins model, Azar balls-into-bins model and balls into non-uniform bins model, the paper brings forward an efficient and balanced non-uniform balls-into-bins load allocation model, which is provided with heterogeneous balls, heterogeneous bins and different bin selection probabilities. The model can achieve rational largest load with high probabilities, at the cost of little time and algorithm complexity. The model is extensible and can be applied in many domains.

Abstract:Sketch-based military marking diagrams consist of many linear and regional symbols. Typically, these symbols are irregularly shaped because they are drawn according to specific terrain or battle scenario with freehand. Therefore, they are also called irregular symbols. Traditional appearance-based methods are not appropriate for recognizing these symbols. A structural recognition method for sketched irregular military marking symbols was proposed. Symbols were decomposed and represented by 9 types of primitives together with 4 types of spatial relationships among them. By matching the primitive counting vector and the primitive relationship matrix of the unknown symbol with those of the templates, the class label was recognized, and their primitive correspondences were also estimated. Experimental results demonstrate that the proposed method is effective and efficient for recognizing sketched irregular military marking symbols.

Abstract:Automatic image scene detection is very important to image annotation and semantic retrieval. According to the requirement of application, eight specific image scenes such as meeting, mass, beach, etc. were focused on. First, to extract the local features of images, the local key points were detected and reduced, and then the SIFT feature descriptors were calculated. Second, a multi-classifier based on support vector machine was constructed and the features for training were selected to achieve relatively accurate detection results. The experiments were designed to mainly focus on two problems, namely the decision of kernel function of classifier and the strategy of feature selection. Experimental results show that the method can achieve relatively accurate and robust results by using radial basis kernel function to construct classifier and the feature extraction strategy of selecting the top n key points by the scale size order. This method is simple and fast, and can satisfy the actual requirements of application for relatively high precision.

Abstract:In HLA simulation, data distribution management (DDM) service provides data filtering capability, which can effectively reduce the transmission and reception of redundant data. During the advancing of large-scale HLA simulation system, much region matching calculation is needed. However, in most of the existing regional matching algorithms, all regions are calculated in every matching calculation process, which results in a waste of computing resources. Meanwhile, the current matching algorithms are mostly based on serial region matching, and the advantage of multi-core cannot be fully taken. Aiming at the limitation of existing algorithms, a parallel region matching algorithm for large-scale HLA simulation is proposed. By this algorithm, the matching process of multiple regions which changes in the same simulation advancing can be calculated in parallel, the advantage of parallel computing environment can be taken. During the process of matching calculation, a method which is based on intersecting information was used. By the history of moving regions, matching calculation only happened within a limited range, and the redundant calculation could be avoided. Theoretical analysis and experimental results showed that the algorithm is particularly suitable for large-scale distributed simulation applications which execute on multi-core computing platform.

Abstract:An improved collision avoidance behavior of multi-agents was presented due to the fact that the existing methods do not comform to the reality and are devoid of universality. By introducing the role and personality parameters, the agents adjust their collision avoidance behaviors. The improved method constructs a link between collision avoidance behaviors and the attributes of real humans. In this way, the consistency and smoothness of humans' motion is retained. So it fits in with the real humans' collision avoidance behavior more tightly. Also it is more hominine and universal than the existing methods. Simulation tests show that the improved collision avoidance behavior accords with the characteristics of the real people. So it can be used in virtual crowd simulation, multi-robot system and multi-agent system more efficiently.

Abstract:To improve the capability of the single-electron transistor (SET) for the practical application, it is inevitable to make the researches under the condition of room temperature. Initialized from the orthodox theory, this research calculated the critical size of coulomb island of SET which can work normally at room temperature: the memory device is 6.5nm, the logic device is 1.5nm; it also calculated the critical size of coulomb island of SET when the energy quantization effect at room temperature, 4.7nm, appeared. Furthermore, it verified and analyzed these two kinds of critical size. In addition, through a comparative analysis, it drew conclusion that all logical devices must consider the energy quantization effect and all memory devices should consider the energy quantization effect at room temperature. The analysis result shows that determination for critical size of coulomb island has important significance for the application of SET.

Abstract:Improved combination weighting radar chart method is provided and applied in synthetic evaluation of power quality. The optimization model was established based on minimizing the deviation between the vectors of evaluation weights before and after the combination weighting. In the method, the sector area was ranked and the angle of the sector area was distributed by the weighting. Moreover, the diagonal of sector area was employed by using the radar chart as index axes. The unattached weighting of every index was not only reflected by the whole hog, but also the interactant was incarnated. Synthetic evaluation of power quality was completed by the area and girth of the radar chart. Verification results demonstrate the reliability and validity of the method.

Abstract:The coordinated observation technique of air and space assets has been increasing in recent years and this trend of earth observation area is expected to continue in the future. A service model for space-aeronautics cooperation earth-observing operations is proposed after analyzing the SWE (Sensor Web Enablement) standard. In this model, in order to provide a common framework for air and space assets, the sensor model language of space-aeronautics observing resources was constructed. The primary focus of this language is to define processes and processing components associated with the measurement and post-measurement transformation of observations. Through introducing the inheritance mechanism, the proposed language can provide more robust definitions of platform, measurement, location, position, constraints and other characters. Besides, to shorten the data acquisition cycle, the standard interface of SWE was encapsulated, and a common end-user can request data directly without detailed knowledge of the platforms state and capabilities. To test the performance of proposed model, some experiments were designed and the simulations and analysis display the feasibility and the adaptability of the proposed model.

Abstract:Blind zones and ambiguities in range and velocity measurement are two important issues in the traditional pulse-Doppler radar. By generating random deviations with respect to a mean pulse repetition interval (PRI), which is converted to the restricted isometry property of the observing matrix, the proposed random PRI radar, based on the compressed sensing theory, provides a new way for moving target detection. In order to solve the problems of 'straddling loss' and clutter perturbation, a precise velocity measurement by local dictionary fractionization is proposed according to the iterative idea and the clutter is suppressed by modifying the optimization problem of CS. The simulation results demonstrate that this scheme has high performance of velocity measurement and clutter suppression.

Abstract:The time delay of output signal is sensitive to the frequency of input signal in LFM pulse compression radars. In light of this, a novel repeat jamming is presented based on pulse separation in which the separated pulses are retransmitted in a rearranged order. After the matched filtering, a set of false targets were induced. The jamming technique was explained in detail with group delay theory. Formulas of separation number on condition that false targets hold amplitude dominance and retransmitted order with the maximum number of false targets were presented. Finally, the theoretical analysis was verified by the simulation results.

Abstract:Based on the independent national protocol (GJB 7377.1-2011), the current research proposes a coding and decoding algorithm for passive RFID tags, which features variation-tolerance of the clock frequency. This algorithm substantially considered the influence upon coding and decoding caused by clock frequency variation, counting error, dividing error, et al. Subsequently, the clock restriction that ensures correct coding and decoding was deduced. and a method to implement coding and decoding was found. As the simulation results show, the proposed algorithm has a low requirement for clock accuracy. It will meet the demand as long as the clock frequency is higher than 1.60 MHz. Furthermore, this algorithm dramatically reduces the difficulty and complexity of hardware implementation. Compared with that of previous works, the power consumption of this work decreases by nearly 50%.

Abstract:The key mechanism of strong target influence over the STAP nonhomogeneous detector was analyzed. Then, considering the declining performance of nonhomogeneous detector with strong interference targets, and the high computational complexity of traditional APR method, a new nonhomogeneous detector based on local template was presented. Compared with the traditional methods, the method proposed can obtain high computational efficiency and more robust detection performance. Finally, experiments with the actual data proved the effectiveness of the proposed model.

Abstract:Aiming at the rehearsal demand in military information system, an efficient and integrated mission rehearsal method based on Spatiotemporal Event Series (SES) is proposed. First the mission expression based on hiberarchy decompounding and materialization strategy by capability was put forward, and then a mission-oriented data application model was advanced for data customization, which minimized the integrative spatiotemporal dataset according to the least demand of battle mission. After that, the event definition model of SES and its data driving pattern were illustrated. Finally the application method was discussed with specific emulation example. The experimental prototype system proved their validity and feasibility. 

Abstract:The bow-tie antenna, which is widely used in impulse ground penetrating radar (GPR), has very low radiating efficiency. It is because that nearly 70% of the radiated energy exists as the form of end reflection, which is obstructive to probing objects. In order to keep the probing ability, the remarkable energy in end reflections is usually dissipated by resistive loading. Through the current research, it was found that, if the exciting pulse is bipolar and monocycle, the radiation efficiency can be significantly improved by utilizing the energy in end reflection, and the improvement can be implemented by optimizing the antenna length. The simulated results show that the radiation efficiency can be increased by nearly 100%. The measured results validate the proposed method again. Additionally, the proposed method is easy to be carried out in applications and of great use.

Abstract:Aiming at the nonlinear characteristics and memory effects of power amplifier, a memory rational function behavioral model, which is based on the memory polynomial model and memoryless rational function model, is proposed. The model coefficients were identified by conjugate gradient method. The estimation of the best model nonlinearity order and the best memory depth was carried out with the minimized the normalized mean squared error (MNSE). The model was validated using multi-carrier WCDMA signal and a MRF6S21140H power amplifier by measurement. The result indicates that the proposed model can achieve better model performance with less number of coefficients, compared with the memory polynomial model and memoryless rational function model.

Abstract:Aiming at the high precise and real-time computation of the satellite orbit in GNSS (Global Navigation Satellite System) simulator with satellite orbit, a fitting method based on Powell optimization theory is proposed. The method converts the fitting method for satellite position to the non-restraint least method, and the parameters of the satellite orbit model were obtained by the optimization theory, with which it is easy to compute the velocity, acceleration and so on. The computation examples show that, in the case of fitting the satellite ephemeris, the new method speeds up the computation three times faster than the direct ephemeris calculation, and the position error is less than 1×10^-4m and the velocity error 1×10^-6m/s. In the case of fitting the GPS precise ephemeris, the new method increases precisely two times efficiency than that of the ephemeris Lagrange interpolation.

Abstract:Usual estimation method of satellite on-board clock short-term stability demands continuous observation of large ground monitoring network and complex algorithm, which is not suitable for single station observation. Based on an analysis of the short-term frequency stability estimation method of satellite on-board clock using observation from one single station, a simpler method combining satellite two-way carrier ranging with GNSS one-way carrier phase observation is proposed. This method is based on GNSS carrier phase observation eliminating geometric distance between satellite and receiver, which is determined by satellite two-way carrier ranging. Performance of this method is evaluated by using BDS data. The estimation result agrees well with result of complex algorithm, and is very close to the smoothed broadcast ephemeris method (SBE method) for average time of 1~1000 seconds with relative error less than 10%, but better than SBE method for average time above 1000 seconds.

Abstract:Considering that there exist many signals with nonuniform distributions and different bandwidths in the complicated electromagnetic environment, a new method is proposed for designing a dynamic channelized receiver. Firstly, a halfband filter was designed and its frequency response was compressed by zero-value interpolation to form periodic spectra. Secondly, the input signal was filtered with the interpolated halfband filter, and then the output of the interpolated halfband filter was subtracted from a suitably delayed version of the input signal. In this way, two channel signals whose spectra are complementary were obtained. Thirdly, the two channel signals were filtered respectively with the analysis filter bank to realize the uniform channelization. Finally, according to the energy detection of sub-channels, the outputs from adjacent sub-channels, which belong to the same signal, were treated as the input of the synthesis section, and the corresponding synthesis filter bank was designed to extract the desired signal. Theory analysis and simulation results verify the validity of the new method.

Abstract:A novel method, the Qth order Mixed Moment Structure Partition Function (Q-MMSPF) method, is proposed for the detection of long range cross- correlations and multifractality. With this method, the multifractal cross-correlation characteristic of sea clutters was investigated. The analysis, based on the real sea clutter data, shows that the cross-correlation multifractality is quite weaker between the two sea clutter series, and the multifractality is significant between two time series of target plus sea clutter, whereas the multifractality is in the middle for the case, which is between target time series and sea clutter time ones. Consequently, an approach was suggested to detect the targets in sea clutter. The test results show that the target can be clearly distinguished from the sea clutter background with the proposed feature-based method. 

Abstract:In a positioning system based on calculating the distance by measuring the time delay, increasing the accuracy of the estimation of time delay is a key factor to improve the performance of navigation receivers. Generally, the off-the-shelf timekeeping chip cannot achieve the performance of high accuracy and low power consumption at the same time, which is especially required in portable and hand-held navigation receivers. A novel architecture of the timekeeping chip was presented to solve that contradiction. In this architecture, the time is compensated directly according to the temperature. And two circuit operation states, the low-power operation and the high-power bursty process, work alternately in turn. The chip can achieve the time accuracy of 0.5ppm and the stand by power consumption of 173μW, which can replace state-of-art commercial RTCs to improve the performance of portable and hand-held navigation receivers.

Abstract:Signals through transmitting and receiving homologous equipment contain analog down conversion, A/D sampling, digital signal transfer and management, D/A recovering and analog up conversion. A signal transmission model of transmitter and receiver homologous equipment is presented, and an analysis of the influence of phase noise on the signal is made. Through an analysis of the frequency standard phase noise changes at down-convert moment and the up-convert moments, an expression for the influence of frequency standard phase noise upon the signals through transmitting and receiving homologous equipment was derived, and a conclusion was drawn that: because of frequency standard phase noise, signals through transmitting and receiving homologous equipment, RF carrier frequency and code rate were multiplied as a constant factor. It could be viewed as the equivalent to a Doppler offset shift, and its trend keeps consistent with frequency standard drift trend. The result is fundamentally different from the general conclusion. It considers that the transmitter and receiver derived by the same frequency standard can fully offset the impact. Finally, by designing the special experimental program, efforts were made to verify the derivation of Doppler drift factor expression. Experimental test results show that the Doppler shift test results are consistent with the formula derived result, and the frequency drift trend is in line with expectations. Therefore, the experimental test results met well with the deduced conclusion from the theoretical analysis.