China Academy of Engineering Physics Terahertz Free Electron Laser(CTFEL) needs a terahertz switch for picking of single-pulse, which can facilitate the experiments that require high peak power but low average power. With the self-induced plasma switching technology, single pulses can be reflected by a plasma mirror on a slab that is generated by short pulse laser. The critical density of the plasma and the threshold of the laser power density are calculated and the numerical simulation of the laser targeting process is carried out by using the radiation fluid simulation software. The simulation results show that the plasma density generated by the laser is much larger than the critical density, which proves the feasibility of the experiment. In addition, the parameters of the experimental equipment and the experimental optical path design are given.

For near field high resolution imaging, near-field radar transceiver modules based on the 220-325?GHz bands, adopt Synthetic Aperture Radar(SAR) and focal plane imaging under the same measure environments. The advantages and disadvantages are compared between SAR and focal plane measurement. Detailed measurement parameters and imaging results comparison will be helpful to make improvement on the resolution of terahertz near-field imaging.

A 340 GHz Backward Wave Tube(BWT) based on Staggered Double Rectangular Waveguide Structure(SDRWS) is studied in detail by computer simulation. Firstly, an electron gun and a permanent magnet focus system are calculated, the results shows that beams with 14 kV-17 kV of voltage, 43.4 mA of current and 18-21 kV of voltage, 56.1 mA of current are produced and maintained, the maximum radius of the beam is smaller than 0.08 mm, and the maximum radius variance of the beam reaches 0.034 mm. Secondly, combining those beams with SDRWS, the interaction in the BWT based on SDRWS is calculated, the results shows that the working frequencies of the BWT cover 326-352.6 GHz when the beam voltage is tuned within 14-21 kV and the output powers of the BWT are larger than 2 W. In the simulations, the radius of the SDRWS is set to be a relatively big value of 0.09 mm, signifying that the manufacturing of the BWT is relatively easy.

Based on electric dipole resonance, a polarization-insensitive broadband metamaterial absorber in W-band is designed. The broadband metamaterial with highly symmetric structure, is composed of the periodic arrays of copper with different sizes. Absorption performance of metamaterial in W band is simulated by Finite Difference Time Domain(FDTD) method, and the physical mechanism of resonance absorption is discussed through electric field and charge distribution. The metamaterial is implemented by Printed Circuit Board(PCB), and the experimental results of absorption are compared with simulation. Experimental results show that the average absorption rate of the metamaterial in W band reaches 84.7%, which is close to the simulation results.

A metasurface with four toroidal dipole resonances in the terahertz band is proposed. The metasurface cell structure consists of a pair of inverted Asymmetric Split Ring Resonators(ASRR) fabricated on a base medium. A typical Electromagnetically Induced Transparency(EIT) phenomenon is observed in its resonant spectrum. The Fano resonance model is adopted to fit EIT transparent resonant spectrum and the good fitting results reveal the coupling effect between different resonant modes. In addition, studies have shown that resonance is very sensitive to the gap of the split ring resonator, and the variation of the gap brings about the frequency shift and a change in Q value of the resonance. This multi-toroidal dipole resonance metasurface not only provides an effective way for realizing the EIT effect but also facilitates the development of more terahertz functional devices.

The development of the Cognitive Radio(CR) technology has benefited from the availability of realistic and accurate spectrum occupancy models. The spectrum occupancy models proposed in the literatures so far are able to capture and reproduce the statistical characteristics of occupied time series. For example, the busy/idle-period lengths of terrestrial wireless network can be fitted by Generalized Pareto(GP) distribution, exponential distribution, etc. However, the traditional parameter estimation distribution cannot give a good fit in satellite link spectrum occupancy. In this context, a method of Kernel Density Estimation(KDE) is proposed to fit the probability density distribution. On this basis, the Auto Regressive Integrated Moving Average Model(ARIMA) and fuzzy neural network are adopted to predict and compare the time series of the spectrum occupancy models. The conclusion shows that the proposed method can describe and reproduce the statistical characteristics of the occupied time series of the S-band used in the satellite downlink more accurately; while the prediction of the fuzzy neural network is more accurate than that of the ARIMA model.

Based on the positioning information and attitude information provided by the high-precision receiver with the inertial navigation module, through the space rotation coordination system method, the satellite angle in the geographic coordinate system is deduced, and the existing antenna-satellite mathematical model is improved. The radius of curvature of the earth's ring and the height of the antenna are introduced, which improves the accuracy of the antenna pointing angle in the geographic coordinate system. In addition, the attitude information is introduced, and the antenna-satellite angle model in the carrier coordinate system is established to reduce the influence of the carrier attitude. Finally, the simulation results show that the improved algorithm model can improve the accuracy of the antenna pointing angle to some extent.

In order to realize the efficient disposal of rocket telemetry image and optimize its encoding process, a new encoding method of rocket telemetry image based on wavelet transform is put forward. On the basis of image wavelet transform, the modified Set Partitioning In Hierarchical Tree(SPIHT) algorithm is adopted to realize the bit flat encoding of important wavelet coefficient in the image by the encoding unit of space direction tree, the optimized interception method of united code rate preferentially cuts out and transmits the important bit flat data of telemetry image. Through the system testing, the results demonstrate that compared with the traditional encoding method of rocket telemetry image, the new encoding method has the advantage of low frame-drop-ratio, good quality of reconstructed image, and efficient encoding, etc, which can meet the engineering requirements of the disposal and transmission of rocket telemetry image.

Distributed Coherent Aperture Radar(DCAR) is an important research direction in the field of radar at home and abroad. Accurate parameter estimation is the premise and core of good coherence performance. Based on the moving target model, a coherent parameter estimation method based on multi-pulse accumulation is proposed. The method performs fast-time and slow-time match filtering for multi-pulse signals, and obtains the results of multi-pulse coherent accumulation. Then the cross-correlation method is utilized to estimate the coherent parameters. The performance of parameter estimation and correlation under different numbers of pulses and different input signal-to-noise ratios are compared by simulation analysis. The simulation results show that the method is feasible and can effectively improve the performance of parameter estimation and coherence in low signal-to-noise ratio.

In the traditional quantum phase tracking method, the output results are usually linearized, which has a strict limit on the local oscillator phase and signal phase, therefore, it is not applicable to the angle measurement by interferometry. In this paper, the quantum homodyne output is transformed and an iterative algorithm for maximum likelihood estimation is designed to realize the coherent state phase tracking. The Fisher information matrix is calculated to show that the proposed method can reach the quantum Cramer-Rao bound theoretically and has the best estimation.

In order to solve the problems of low test speed, inaccurate analysis of transient signal detection and poor real-time performance of traditional spectrum analysis systems, a Frequency Mask Triggering(FMT) technology combined with reconfigurable computing is proposed to achieve ultra-high speed data capture, detection and analysis. The digital fluorescent display technology is adopted to make the displayed signal spectrum more real-time and intuitive. The measured results show that the system has improved the accuracy of signal analysis within the acceptable performance loss range. The reconfigurable calculation makes the system run more efficiently, reduces the energy consumption, and enables the system to achieve real-time and accurate analysis on the transient signals and complex signals even under large bandwidth conditions.

It is an effective way to use the integrated pole piece structure in order to improve the output power of millimeter wave Folded Waveguide(FWG) Traveling Wave Tube(TWT). Based on the circular beam electron optical system, an integrated pole piece structure is designed for E-band folded waveguide TWT. In this paper, the cold characteristic parameters of slow wave structure are designed and simulated by using the Computer Simulation Technology(CST), and the integrated pole piece focusing system is designed. The magnetic field is simulated and verified by Operating Environment for Electromagnetic Research and Analysis(OPERA). The final Particle-In-Cell(PIC) simulation calculation results show that the output power of more than 1?kW can be obtained in the frequency band of 61-71 GHz. The integrated pole piece structure not only provides strong axial magnetic field, but also has the advantages of compact structure and good heat dissipation.

Based on odd-even mode theory and multidirectional-feed coupling, a cross-shaped new structure Tri-band Band-Pass Filter(TBPF) with folded stub is studied and designed on the basis of cross-shaped Dual-band Band-Pass Filter(DBPF). The structure analysis shows that the TBPF based on multidirectional-feed has the characteristics of flexible and independent adjustment at the three center frequencies, easy cascade structure, miniaturization and less frequency design parameters. The simulation results show that the added feed-direction excites the third passband of the filter. The designed TBPF has good performance in 5G medium-low frequency band and Indoor WiFi band. Literature comparison shows that the proposed multi-directional feed design method reduces the structure complexity and the number of frequency design parameters of the resonator. Meantime, this method can provide reference for increasing passband numbers of the basic resonator.

Aiming at solving the problem that the non-uniformity of spatial frequency affects the accuracy in the process of two-dimensional cross-section imaging, an interpolation optimization algorithm based on truncated sine cardinal(sinc) function is proposed. The algorithm takes the sinc function as the convolution kernel to interpolate the data. Compared with the cell element interpolation method, the obtained scattering interpolation amplitude is closer to the actual value, and the imaging accuracy is higher. On this basis, sinc interpolation requires infinite summation and the amount of data to be calculated is huge, therefore, the interpolation summation should be truncated. The cross-sectional images formed by different truncation points are compared and processed by windowing to further optimize image quality. The simulation results verify the feasibility and accuracy of the optimization algorithm.

A circuit topology based on six-port network is presented, which can be adopted to effectively suppress the leakage signal. This six-port network is mainly composed of three 3?dB hybrid couplers and an unequal Wilkinson power divider. Among the two output ports corresponding to the receiving signals, two leakage signals of the transmitting antenna are offset each other for their equal-magnitude and out-of-phase, which is benefit to achieve a high level of transmitting(Tx)-to-Rx isolation in the radar network. In order to demonstrate the Tx leakage canceller, a circuit topology is designed and simulated from 22 GHz to 26 GHz. In the operating band, the isolation of the Tx leakage canceller is lower than -29.5 dB, and it achieves the maximum isolation -44 dB at its center frequency. As shown, the circuit topology efficiently improves the isolation of single-antenna radar system and performs cancellation for the Tx leakage power.

The purpose of this study is to obtain the estimation of the electromagnetic interference caused by the antenna feed system to the given equipment nearby, so as to optimize the design parameters of the antenna feed system. In this study, the magnetic field module in COMSOL is utilized to simulate the electric field intensity and current density excited by the whole antenna feed system under the external electromagnetic field. The model space is truncated by infinite element domain. The induced current is mainly distributed on the inner and outer surface of the solid of the antenna feed subsystem, and its value is generally about 650 A/mm2, while the induced current in the solid of the antenna feed subsystem is less than 6 A/mm2. For the region with thin wall, the induced current in the solid is also large. For a given excitation, the wave reaches two line probes at the same time and produces induction current. The simulation results show that the coupling electromagnetic effect of the antenna feed subsystem on the external radiation electromagnetic source is mainly concentrated on the surface of the solid part, which causes the signal to change and has a great effect on the bit error rate.

In order to overcome the problem of false detection and missing detection when the threshold is not set properly, an image copy-paste tamper detection algorithm based on the optimal correlation rule of circle segmentation coupling is designed by using Cross-Correlation Function(CCF). The FAST operator is introduced to extract the image feature points accurately by calculating the gray value of the pixels and their adjacent points. Using the histogram information corresponding to the feature points, the principal direction of the feature points is obtained, and the neighborhood circle of the feature points is established in this direction. Through the segmentation of the circle, the gradient features of each segmentation area are obtained, and the feature vectors of the feature points are obtained. The correlation degree between feature points is calculated by CCF to construct the optimal correlation rule to complete feature matching. The Euclidean distance between feature points is calculated by matching the feature vectors of feature points. The feature points are clustered, and the copy-paste tampering content is locked to realize forgery detection. The simulation experiments shows that the detection results of the proposed algorithm for copy-paste tampered images are more accurate than those of the current algorithm for copy-paste tampered images, and it has higher robustness for content modifying such as rotation and zooming.

Inspired by the classical segmentation algorithm, this paper proposes a grayscale image segmentation algorithm based on the image complexity. Firstly, the grayscale image is divided into background and target categories by the threshold, the corresponding histogram and total number of pixels are calculated, as well as the complexity of objects. Secondly, according to the image complexity segmentation criterion, the image complexity of each gray level is calculated. Finally, the optimal segmentation threshold is obtained by the minimum value of the object complexity. Compared with the other three classical algorithms, the experimental results show that the proposed image segmentation algorithm is fast, stable and efficient.

In order to overcome the discontinuities and Gibbs phenomenon in many remote sensing image fusion methods, this paper designs an image with Non Sampling Shearlet Transform(NSST) coupling detail enhancement factor by using the gray level and gradient information between pixels fusion method. The intensity(I) component of Multi Spectral(MS) image is separated by Intensity-Hue-Saturation(IHS) transformation. The high and low frequency coefficients of I component and Panchromatic(PAN) image are extracted by NSST. Based on the low-frequency coefficient corresponding to component I, the filling coefficient is calculated by the spatial frequency characteristics of the image. The low-frequency coefficient corresponding to the image is filled into the low-frequency coefficient corresponding to component I, and the low-frequency coefficient is fused. The gray level and gradient information between pixels are utilized to construct detail enhancement factors to measure the differences between pixels and their neighbors, and then the high-frequency coefficients are fused. Based on the fusion coefficient, IHS and NSST inverse transforms are adopted to reconstruct the coefficients, and the fusion results are obtained. The experimental results show that the image fusion algorithm has higher mutual information value, lower spectral deviation value and better spectral and spatial characteristics than the current image fusion algorithm.

In order to improve the retrieval accuracy of images in datasets, an image retrieval algorithm based on weighted distance and multivariate polar harmonic transformation is designed by making full use of the texture and shape features of the query object. The color features are extracted in the Hue-Saturation-Value(HSV) space of the query image. Bessel K-distribution and Non-down Sampled Shearlet Transform(NSST) are introduced to obtain the texture features of the query image for improving its robustness to blur and brightness transformation. With the help of the Quaternion Polar Harmonic Transform(QPHT) mechanism, the QPHT modulus of an image is regarded as a shape feature to improve the robustness to noise and geometric transformation. By fusing the three features, the corresponding feature distance between the query image and the database image is calculated, and the corresponding weight of them is given to measure the similarity so as to output the retrieval results accurately. The test data show that this algorithm has higher retrieval accuracy and robustness, which can still accurately retrieve the target under various geometric transformation attacks compared with the current content-based image retrieval technology.

According to the high real-time requirements of the 3D visual simulation scene, higher requirements are put on the modeling and optimization of the 3D model. Using the software of Multigen Creator and Terra Vista, taking the "MQ-1 Predator" drone as an example, based on the virtual reality technology, the Degree of Freedom(DOF) is controlled by the process of constructing the drone model. Key technologies such as DOF control technology, model database optimization technology and texture mapping technology are utilized to realize the construction of the dynamic entity model of the drone and the simulation of mission flight. This paper studies the key technologies of virtual environment visual simulation modeling based on drones, realizes the construction of visual simulation models, and models virtual environments to generate efficient and optimized models for subsequent real-time simulation. The application lays a solid foundation for the optimization of 3D models and the precise matching of terrain, imagery and GIS(Geographic Information System) data.

In order to resolve the security monitoring problem of critical infrastructure based on Wireless Sensor Network(WSN), an adaptive intrusion detection scheme in data fusion stage is presented. The presented scheme takes the cluster network structure based on weight as the foundation, respectively using the anomaly detection subsystem and the misuse detection subsystem to detect the known attacks and the unknown attacks, and then adaptively adjusts the proportion of fusion data transmitted to the two sub-systems by tracking the Receiver Operating Characteristics(ROC) and the reward and punishment mechanism of the two sub-systems, so the intrusion detection of critical infrastructure in the data fusion stage can be realized. The simulation analysis indicates that the accuracy rate and detection rate of the presented algorithm is as high as 99.6% and 94.9% respectively, and can be improved at least 0.5% and 10.2% by comparing with other classic intrusion detection systems based on cluster structure.

Aiming at the problem of insufficient security of traditional cross-domain key agreement protocol, a new cross-domain quantum key agreement protocol is proposed. In the certificateless key negotiation system, the combination of quantum key negotiation and classical cryptographic algorithm is adopted to improve the ability of the protocol to adapt to the existing communication network architecture. The key negotiation process uses three-particle quantum teleportation, and the quantum state non-cloning theorem can guarantee the security of the key during the negotiation process. Compared with other schemes, the proposed protocol has higher quantum bit efficiency and can resist various internal and external attacks such as man-in-the-middle attacks and replay attacks.

In order to improve the data transmission convergence ability of Wireless Sensor Networks (WSNs), a data transmission and aggregation algorithm based on sparse dense array transmission mechanism is proposed. A new transmission matrix is designed by introducing the kernel generation function to quantify the connectivity and load between cluster head node and sink node for improving the evaluation ability of cluster head node transmission effect. And the eigenvectors are sorted by column and convolution algorithm to reduce the transmission value of cluster head nodes for effectively reducing the load of cluster head nodes. The tree decomposition mode is utilized to search available Hamiltonian circuits, and a convergence stability method based on path decomposition optimization mechanism is constructed. The Hamiltonian addressing mode is adopted to optimize the data link between leaf node and root node one by one so as to enhance the coverage ability of cluster head nodes and improve the stability performance of data transmission process. The simulation results show that, compared with the current common algorithm of a stable clustering for WSN data based on threshold filtering and fuzzy clustering, and the energy-saving and reliable multi-path data transmission in wireless sensor networks for medical applications, the proposed algorithm has higher concentration of message transmission, stronger control ability on transmission link jitter, and higher network bandwidth.

In downlink Cloud Radio Access Network(C-RANs), the data is transferred from a Base Band Unit(BBU) in the core network to several remote radio heads via a set of edge routers over capacity-limited fronthaul links. The remote radio heads then send the received signals to their users via radio access links. Now, energy efficiency of C-RANs is a topic issue. Therefore, the general downlink of C-RANs is studied in order to maximize the network energy efficiency by jointly optimizing User Association(UA), Radio Remote Head(RRH) activation, data rate allocation and signal precoding. By employing the successive convex quadratic programming framework, an iterative algorithm is proposed to solve the challenging mixed-integer nonlinear problem formulation. Simulation results show that the proposed joint optimization approach significantly improves the energy efficiency.

Model-driven design has been used in embedded system software design. The software architecture model and detailed functional model are the focuses in the software design stage. There are many languages and tools for the embedded system software modeling. The architecture of embedded software can be built by the Architectural Analysis and Design Language(AADL) model, and the logic function of embedded software can be described by the Safety Critical Application Development Environment(SCADE) model. The integration of the two models can meet the modeling requirements of outline design and detailed design of embedded software. AADL and SCADE are adopted to model the architecture and function of the software of an aircraft control system, KCG tool is utilized to auto generate C code from SCADE model, and the aircraft control system software is partly designed through the integration of handmade and auto-generated codes. Actual application indicates that AADL associated with SCADE is suitable for model-driven design applied in the embedded software design.

To detect the center and radius parameters of defect circle, the paper proposes a detection method based on random sampling and voting strategy. Through randomly selecting three points from the target edge, two arbitrary chords are obtained, and the intersection points of two vertical bisectors are calculated. Several candidate center coordinates are obtained by repeating the above process. By using voting strategy, one can extract the coordinate value holding the highest frequency and so the ideal circle’s center is detected. Then the radius parameter is obtained by using the voting strategy again. The results of simulation and experiment show that the proposed method has strong adaptability and robustness and may be applied to different types of defect circle. In addition, it is accurate and reliable, easy to realize, and can meet the requirement of engineering application.

The rapid development of tourism and Internet leads to the increasingly serious problem of tourism information overload. Therefore, tourism recommendation method is very important to solve the problem of information overload. Traditional recommendation algorithms only calculate similarity between users and items based on the score and basic attributes, behavioral needs and comments with tourist emotional factors are ignored. In this paper, Convolutional Neural Network(CNN) is utilized to classify the feature extraction of text comments, Pearson similarity formula is adopted to calculate similar user groups, and Mean Absolute Error(MAE) is employed to evaluate the error of the results. Compared with the traditional collaborative filtering method, the experimental results show that the proposed model can effectively reduce the prediction error.

Voltage mode Buck-Boost converter is a typical non-minimum phase system. According to the working characteristics of the DC-DC buck-boost converter, the small signal model is established by using the state space average method, and the Proportional-Integral(PI) controller parameters are designed. Buck-Boost converter is a time-varying nonlinear system. Traditional PI control is difficult to achieve the optimal control effect, so the fuzzy PI control is adopted to avoid the disadvantages of PI control. Aiming at the problem that the control precision of fuzzy PI control becomes worse when the controlled variable changes greatly, a variable universe fuzzy PI controller with adaptive scaling change in the fuzzy universe is designed to control the Buck-Boost circuit. Through Matlab/Simulink environment simulation, the experimental results show that the variable universe fuzzy PI control has better dynamic control performance.

With the development of phased array radar technology, as the key device of T/R module, front-end module is evolving towards the directions of high performance, high reliability, multi-function, miniaturization and low cost. The module is implemented by microwave hybrid integrated process and micro-assembly technology. In the case of input power of 6 to 8 dBm, the output power of 200 W is achieved, with efficiency as high as 50%. The gain of the receiving channel is larger than 30 dB and the Noise Figure(NF) is less than 1.5 dB in defined bandwidth. Test results show that the module performance is up to the specifications and sufficient to meet the requirements of practical application.

Capacitance voltage dividers are often utilized to monitor voltage values in high power electrical pulse devices. The amplitude linearity of the capacitive voltage divider characterizes the consistency of the voltage value monitored. In this paper, the principle of the ceramic capacitance divider is analyzed, and the performance of the ceramic capacitance divider is simulated by the simulation software under the rectangular pulse high-voltage source(500?V-4?kV) with a pulse width of 200?ns and the impulse high-voltage source(10?kV-100?kV) with a half-width of 10?μs respectively, and the design and processing are carried out. The results show that the amplitude linearity of the ceramic capacitor voltage divider is 1.5% within the range of 500?V-100?kV, and the linearity is good. The voltage divider calibrated under small signals can be applied to the measurement of large signals.

There are some disadvantages in the simulation test of transient dose rate radiation effect, such as limited test resources, strong environmental electromagnetic interference and low repeatability. There are some disadvantages, such as limited test resources, strong electromagnetic interference and low repeatability. In this paper, the pulsed laser simulation test technology of transient dose rate effect is developed, and a complete and fine ground test system is constructed with 1?064 nm laser. The transient dose rate effects of different process nodes, different channel types and different substrates are experimentally studied by using this system. The experimental results show that under the same conditions, the photocurrent of bulk silicon devices is more than 10 times larger than that of Silicon-On-Insulator(SOI), and the photocurrent is more affected by the source-drain voltage than SOI.