Abstract:Hole inflation and tapering techniques have been rated effective methods to change the structure parameters of the photonic crystal fibers (PCFs). Hole inflation can change the air-filling faction, that is, the hole diameter and pitch of the PCFs and tapering can change the core diameter while preserving the cross section of the original PCFs. Controllable-change of the structure parameters of the PCFs allows some special PCF devices to be made,and is of great significance to further realize the potential applications of PCFs.

Abstract:All-solid photonic bandgap fibers have being used for supercontinuum generation. The spectral rang of supercontinuum is controllable with the use of bandgap. But the dispersion has significant effect on supercontinuum generation. In different bandgaps of the same photonic bandgap fiber and in the same order bandgaps of different photonic bandgap fibers, the group velocity dispersions were calculated with plane-wave methods. The results indicate that the relative position of the zero dispersion wavelength in the bandgap strongly depends on the location of the corresponding bandgap. Zero dispersion wavelength is in the proximity of the short wavelength edge of bandgap in long wavelength region.However, it is located near the long wavelength edge of bandgap in short wavelength region. From the calculated waveguide dispersion and material dispersion, it can be found that it is material dispersion that affects the relative position of zero dispersion wavelength in bandgap.

Abstract:To study temperature variation of the detector chip irradiated by spectral unrelated laser, the platinum resistance thermometer is used to monitor temperature of the chip's back surface. The electron-hole pairs separative duty of the field in the junction depletion region is calibrated. The temperature of front chip surface is obtained by the experimental method of laser combination. It is found that both front and back chip surface have temperature rise, but the temperature of back chip surface is always higher than that of the front one in the irradiated process.

Abstract:Reducing the diameter of the discharge tube used in the discharge driven HF/DF chemical laser is useful for integration of multi- module, and may be useful for promoting the performance of the laser as well. The glow discharge characteristics and laser operated parameters of three different discharge tubes were experimental studied, and the diameter of the discharge tubes was 28mm, 20mm and 16mm, respectively. When NF₃gas was injected, the plasma necking phenomenon occurred in all three discharge tubes. For the laser which used the 20mm diameter discharge tube, the plasma necking phenomenon was the weakest, the total consume of working gas was the least, the output power and the electro-optic transfer efficiency were the highest, and the laser output power promotion effect by secondary He was the most outstanding. Through comparison, it is suggested that the stability and volume of the plasma are two intuitionistic parameters for judging the performance of discharge tubes.

Abstract:Ceramic laser, possessing the advantage of polycrystalline inhesion, has the potential to be high-energy and high-light beam quality laser. The current study researched into the performance of domestic Nd:YAG ceramic created by Shanghai institute of ceramics and realized the actively and passively Q-switched ceramic laser side-pumped by flash lamps. The average pulse energy could be above 100mJ and the repeat rate is up to 20Hz. The peak power reaches nearly 10 MW. The research result in the confirmation of ceramic laser in the field of high-energy laser, and a probe in the short pulse ceramic laser with high energy.

Abstract:In order to study the effect of background pressure on the output performance of HF laser, and to provide referenced data for the “Base-ejecting” HF chemical laser, a series of experiments were conducted with different background pressure for a certain HF laser. From them, the output power and faculae were obtained. The results reveal that, the upper limit of background pressure for lasing is 4 kPa. In addition, the dependence of lasing with diffusional mixing on the cavity pressure is deep, on the other hand, lasing will be generated in high background pressure with injection mixing.

Abstract:The experiment of 975nm continuous wave laser irradiating carbon-fiber reinforced resin composite was studied, while the front surface of the target was provided with and without tangential airflow. Analysis indicates that the loading of tangential airflow can enhance the damage effect of laser on carbon-fiber composite. The failure mechanism of carbon-fiber composite irradiated by laser is preliminarily studied in theory. Based on the oxidation characteristics and the oxidation reaction mechanism of carbon, the oxidation rate equation of carbon-fiber was obtained. The three-dimensional temperature field model of thermally decomposing resin composite irradiated by laser was solved using modified smoothed particle hydrodynamics, the failure mechanism of carbon-fiber composite irradiated by laser was numerical simulated. Simulation results proved to be consistent with experimental results.

Abstract:In order to make a theoretical description of the multi-wavelength active coherent beam combination(CBC), and to figure out the significant factors influencing the combination effect, a mathematical model was established based upon the fundamentals of CBC. The combination effect of each frequency component and the whole combination effect are obtained on the calculation of the nine-wavelength seven-channel CBC example with various optical path differences. Only the central frequency component is coherently enhanced and the whole combination effect degenerates to non-coherent beam combination on the condition of large optical path difference. More components are coherently enhanced and the whole combination effect is improved when the optical path difference is small. The optical path difference is the key in multi-wavelength active CBC. To achieve excellent combination effect, the optical path difference should be adjusted to the same and then the phase of each channel is locked.

Abstract:Because of the deformation of shock absorbers, the dither RLGs inertial measurement unit (IMU) can not be calibrated using a precise turntable as attitude reference.This paper introduces a new calibration method for dither RLGs IMU,firstly, the RLGs were turned off and the IMU without absorbers was fastened on a precise turntable to calibrate the error parameters of accelerometers;then the shock absorbers were installed on IMU,paper designed a procedure for the calibration of RLGs error parameters. Further more,according to the output error equation of the RLGs, a systematic calibration algorithm of the RLGs IMU was proposed based on a 21 dimensional kalman filter using velocity errors as measurement vector.The simulation results indicate that the novel calibration method can accurately identify RLGs scale factor errors,drifts, misalignments errors and accelerometers drifts, and the accuracy of this method satisfy the requirements of high precision inertial navigation system.

Abstract:Chemical equilibrium compositions, total temperature and total pressure of HF chemical laser combustor for NF₃-D₂-He reaction system were calculated by combining minimum Gibbs' free energy method and mass flux conservation principle. Mole flux of F atom as a new parameter that can be used to express yield of F atom was presented. The effect of changing fuels' mass flow rates on combustor's characteristics was analyzed with emphasis. When the compositions proportion in combustor was maintained constant, increasing of mass flow rate of F atom and total pressure of combustor was in proportion to the increasing of total mass flow rate. Changing of total pressure had no obvious impact on adiabatic flame temperature, degree of F₂ dissociation, and mole fraction of F atom. The changing of mass flow rates of NF₃ or D₂ was able to adjust the oxidizer excess factor. In comparison with changing mass flow rate of D₂, changing mass flow rate of NF₃ could acquire much higher mole fraction and mole flux of F atom, much smaller fluctuating amplitude of combustor's total pressure. Increasing mass flow rate of He decreased adiabatic flame temperature and mole fraction of F atom observably. Whereas degree of F₂ dissociation and mole flux of F atom maintained a high level still when primary diluent ratio was less than 15.

Abstract:An object tracking algorithm by associating tracklets with the best bidirectional spatio-temporal continuity was proposed. First, reliable tracklets were generated by a primitive frame-by-frame association; then tracklet's motion, position and color features were computed and refined by applying Kalman filter and weighted mean method respectively; finally, the best spatio-temporal association of tracklets was achieved through an iterative association by computing spatio-temporal continuity between tracklets. Experimental results prove that multiple objects can be successfully tracked under occlusion both by other object and scene object.

Abstract:Aiming at the hot issue about the sink node in most traditional data collection protocols in wireless sensor networks, the study presented a data collection method using mobile sink. Data collection problem was decoupled to a dominating set construction and travelling salesman problem. A distributed algorithm was presented for constructing dominating set. According to the result set, approximate algorithm was used to generate a path for sink. Simulation results show that the approach proposed can reduce communication overhead and balance the load.

Abstract:With the purpose of detecting micro-Doppler under the background of missile confrontation, the influence of the radar location was researched. It was proved in theory that when the dimension and the dynamic parameters of the precession target are invariable, the micro-Doppler is only determined by the angle which is between the radar sight and the precession axis called the average sight angle. In the research, the change of the average sight angle and the micro-Doppler bandwidth caused by different locations of radar was studied. At the same time the simulation results in the typical scenarios were shown in figures, which validated the ideas. The conclusion of this paper will benefit how to deploy the radar for detecting ballistic targets.

Abstract:An adaptive threshold estimation method for multiplicative speckle denoising in SAR images was proposed, based on wavelet domain merging with translation invariant denoising. The subband threshold was derived using bayesian estimation theory and a new probability density function. The method was applied for speckle SAR images by using logarithmic transformation. Theoretical analysis and experimental results demonstrate that the method is computationally more efficient, and displays better noise removal as well as better preservation of sharp features.

Abstract:From the point of that knowledge can be seen as the ability to perform classifications, a new kind of measurement of rough set, based on general binary relations, was presented. It is found that the α entropy and α accuracy increase monotonously while α roughness decreases monotonously as the information granularities become smaller. By means of the α entropy knowledge, definitions of α accuracy and α roughness were derived, and the α accuracy and α roughness are more reasonable and accurate than those obtained in the classical methods. These results develop the theory of uncertainty and provide theoretical basis for knowledge acquisition in information systems based on general binary relation.

Abstract:Multi-Carrier Phase-Coded Signal (MCPC) has caught much attention of researchers recently. The flexible structure enables its balanced and adjustable performance, while enhancing the demand of parameter designing. Current designing methods can hardly achieve satisfied ambiguity diagram and envelope control simultaneity, and they mostly perform the research with less sub carriers. This research proposed a random shifted phase-coded MCPC signal, whose ambiguity diagram is ideal thumbtack shaped. To deal with its fluctuating envelope time-frequency clipping iteration was brought forward, after which optimizing method was used to further reduce the side lobes of auto cross function (ACF). Simulation results show that the designed signal keeps ideal ambiguity diagram and low PMEPR at the same time, while maintaining good ACF on sub carriers. Compared with reported MCPC at present, this signal is more suitable for practical use in radar.

Abstract:Aiming at the problem of estimation of the sources number in the underdetermined mixture signals, this paper propose a algorithm based on spatial time-frequency distribution (STFD) and singular value decomposition (SVD) without the assumption of sparsity and independence. First, the time-frequency distribution matrices corresponded to the auto-source TF points was stacked in three-order tensor, then the entries of the tensor stacked in matrix and SVD on this matrix was performed to finish the estimation of the sources number. The efficiency of the algorithm was proved in theory. Computer simulations show that the proposed recognition algorithm is high in performance.

Abstract:Information Geometry, a new subject originated from differential geometry, studies the statistics problem in manifold and metric space, and serves as a new solution method for the problem involved in radar signal processing and data processing. In the current study , radar echoes were modeled as the complex multivariate Gaussian distribution, and a kind of CFAR detector was proposed based on the Riemannian geometric structure of the manifold, and the false alarm probability and detection probability was analyzed. Simulations show that the detection performance of the information geometry method was better than the traditional coherent accumulation method for the small pulse number case. The findings of the research will be helpful to improve the detection performance of mechanical scan radar system at low PRF work mode.

Abstract:A method of automatic building height extraction by Fusing Catadioptric Panoramas and Remote Sensing Images was presented for solving the problem about building height extraction in 3D city reconstruction. The method has three steps. First, images between Catadioptric Panoramas and Remote Sensing were registered. Second, the building in the Catadioptric Panoramas were extracted by using the previous result of image registration, Finally, the building height with catadioptric projection model was calculated based on the information of the top and bottom borderlines. The whole processing of building height extraction was completed automatically. Experiments show that this method is feasible and can obtain a precise result, especially for dwelling houses, error reaches no more than 4%.

Abstract:Modeling of earth observing satellite (EOS) application task is an important part in EOS mission planning and scheduling. From the perspective of the system components, characters of application tasks of EOS and modeling factors, a detailed analysis of EOS application task was accomplished. Among them, task periodicity, strict time limits, entity property complexity and suddenness of mission were investigated in characters of EOS application task. The constraints of task and actions were taken for the main modeling factors and applied to model EOS application task by plan domain define language (PDDL). Finally, through designing a case that EOSs take images from point target, the modeling method presented is illuminated and validated.

Abstract:In current space-based reconnaissance task pretreatment process, resource allocation generally lies on task requirements, which may lead to load imbalance. In light of this, a matching method that considers both task requirements and resource load was presented. For the sake of load balancing, the key task elements and their description method were analyzed. Based on the task flow model, formula and algorithm for calculating the probability of the executed task were available, then the execution probability were used to measure the load status of satellite resources. Finally, the research put forward a load balancing model and a corresponding heuristic algorithm for matching reconnaissance tasks and satellite resources, which takes into consideration the workload, priority, quality of tasks and execution probability. Simulation results show that the proposed load balancing method can effectively improve the utilization of satellite resources and reconnaissance benefit.

Abstract:Simulation models of C⁴ISR possess the properties of multi-granularity in development and relating to many application domains. During the phase of development, those simulation models may have pertinent relationship. The current research proposed simulation model system for C⁴ISR systems development, which provided simulation model with standardization description. First, simulation concept model wasestablished, which consists of simulation entity, organization structure, interface junction, information interaction, function, activity and dynamic behavior for simulation entity to reflect C4ISR systems characteristic abstractly. Simulation component model was designed with hiberarchy idea, which is composed of atomic component model and complex component model. Each component model consists of component description and component implement, whose component description adopts formatting form to describe component model roundly. Finally, component model was encapsulated in Web Services and published as simulation model service which is described in formalization. Through simulation model system and model specification description, simulation models of each development phase can be associated organically, which promotes model reuse and interoperability,and improves system development simulation efficiency.

Abstract:BTT(bank-to-turn) missiles have overwhelming advantages than STT(skid-to-turn) missiles in aerodynamic efficiency, maneuverability, controllability, and the like. However, traditional methods of guidance law designing for BTT missiles face many challenges due to its motion coupling characteristic. In this paper the researches in BTT missile guidance law designing were surveyed. In detail, the basic problem for BTT missile guidance was described firstly, and the difficulties in guidance law designing were analyzed, that is, the factors such as motion coupling, multi-constraints, target maneuver, dynamic effects of missile body, and so on, should be considered synthetically. Then the state of the art in BTT missile guidance law designing was discussed, which could be classified as channels decoupling method, sphere coordinate method and modern geometry method. Finally the further directions of BTT missile guidance law were proposed.

Abstract:Base Object Model (BOM) is a modeling standard for facilitating model composition and reuse. For the problem of conceptual model reuse, similarity between two conceptual models was presented to describe their similar degree. A similarity evaluation algorithm for computing the similarity between two conceptual models was also presented. According to the definition of conceptual model, similarity evaluation of algorithm was induced into two basis processes: name similarity computing and optimization matching computing. How different combinations of interface weighted parameter and behavior weighted parameter of the algorithm to affect the precision and recall was also studied. JC3IEDM was applied as benchmark to evaluate the algorithm. The result reveals that the similar degree of elements and structure between two conceptual models can be represented by their similarity collect. Similarity between two models can be computed by the algorithm. When the recall of algorithm is 100%, the precision is greater than 75%.

Abstract:Some limitations of the Hilbert transform (HT) for computing instantaneous characteristics of complicated mono-component signals were analyzed. As an enhancement of the HT, an algorithm named empirical AM-FM (amplitude and frequency modulation) demodulation was investigated and then improved. Firstly, the weighted smoothing phase-difference method was applied to this demodulation algorithm to increase the precision of instantaneous frequency for noisy signals. Secondly, by combining the Empirical Mode Decomposition (EMD) and the improved empirical AM-FM demodulation algorithm, a method suitable for instantaneous characteristics extraction of complicated multi-component signals was proposed. The validity of the improvements was confirmed by numerical simulations and experimental signals.

Abstract:In view of the lacking of theory and method in determining missile system level testability indices, this research presents a testability indices determining method oriented to mission requirements. The missile mission is divided into four phases, such as storing, combat preparation, disposition and launch. Then the test requirement of each phase was proposed. Based on the performance requirements of store availability, combat preparation mission success rate, disposed combat readiness rate and launch mission success rate, some testability requirement models were built. The relationship between the performance requirements and testability parameters were given, and the testability parameters which were the key factors on the performance were selected. It defines an aggregative index to evaluate the missile mission performance, and then modifies the mission phases performance requirements to unify the testability indices which may vary in deferent missions. The credible testability indices are gained synthetically.

Abstract:The technology of accelerated testing with competing failure is the foundation of application extending from products with simple structure to products with complex structure. Designing optimal test plans, which obtains better result with lower cost, is one of the main research points in the technology. Traditional analytical optimization has some shortcomings, such as complexity of deduce process. To overcome these shortcomings, this study presents a new method of Monte Carlo simulation based optimal designs for accelerated testing with competing failure. When the candidate plans are too many, curve fitting can be introduced to decrease the amount of calculation by reducing the number of test plans for simulation. Two cases of simulation based optimal designs are demonstrated by direct and indirect optimization respectively, which shows that the proposed method is suitable for application. Results of sensitivity analysis show that this method is robust.

Abstract:The dependence of various STI depths on charge sharing in 90nm dual well CMOS technology was investigated. TCAD simulation results show that increasing STI can restrain charge sharing of NMOS effectively, and 550nm is the effective depth for the prevention of charge diffusion, beyond which the collected charge almost keeps constant; for PMOS, charge sharing decreases linearly with the increment of STI depth. This conclusion is useful for irradiation-hardness.

Abstract:There exists a large gap between the data input speed and processing speed in large-size sliding-window applications. To shorten this gap, a parallel processing scheme was proposed, which achieved high data reusability and parallelism with memory resources as few as possible and memory access control logics as simple as possible. The scheme combined the advantages of parallelism among different sliding-windows and parallelism among different data in a single window. For different windows, they were divided into groups and mapped into multiple processing elements. For the data in a single window, multi-module memory structure was introduced to buffer them, where module assignment and addressing scheme was designed for conflict-free parallel access. Experimental results on FPGA show that this approach can improve the processing speed significantly without incurring too much memory resources and too complicated memory access control logics.

Abstract:High-performance computing has witnessed a tremendous growth and acceptance over the last decade, primarily due to the availability of clusters. The performance of these clusters hinges upon the communication interface. User level communication based on storing address translation table in off-chip SRAM has deeply increased the design complex and cost of chip and system. The paper put forward and implemented a novel Free-Memory communication interface of many cores processor which differs from traditional HCA based on I/O bus, without local memory interface and reduced cost of address translation by efficient cache management method. Experimental results show the communication interface which we implemented not only can reduces the design complex and cost of chip and system, but also can achieve better bandwidth and latency than infiniband QDR HCA.

Abstract:In the field of computational fluid dynamics, the upwind finite volume method (FVM) is widely applied to solve the complicated flows with unstructured grids as the volumetric representation. It produces unstructured-grid cell-centered data at the center of each cell（control volume）with the flow discontinuity constraint on the inner-face between face-adjacencies. For visualization, existing reconstruction approaches violate the discontinuity constraint. As a result, the image has low quality due to the lost information of the discontinuity. This research presented a method to reconstruct the discontinuous states at a sample based on the dual control volumes on the framework of multi-pass raycasting. It guarantees that the field on the inner-face is discontinuous between face-adjacencies, which is in accord with the solution of the numerical computation. We also designed a synthesizer for the discontinuous segments based on the reconstruction above, so that the discontinuity information can be transferred to rendering data. The experiments demonstrate that our approach can obviously improve the image quality and clearly visualize the features in the flows.

Abstract:Subspace obtained by SVD is fit for complex interference and few sample, but computation of this method is large. A new subspace projection approach was proposed. It relaxed the requirement of the diagonal matrix in SVD to block lower triangular matrix and reduced the computation while the anti-jammer performance was not affected. The block lower triangular matrix can be computed by Givens rotation. Givens rotation has modular structures and is suitable for parallel computation. Based on the characters of GNSS signal, noise and jammers, it is applied to interference suppression in GNSS receiver. The numerical simulation demonstrates that the performance is effective.