Abstract:By using a femtosecond laser as the excitation source, a two-photon fluorescence microscopy system was constructed to conduct some researches on two-photon microcsopy. Firstly, the advantage of introducing an ultrashort pulse mode-locked laser was verified, the definite expression of saturation power was calculated, and the resolution of two-photon fluorescence microscopy was deduced. Then based on the femtosecond laser, microscope, data acquisition device, control equipment and the software that we wrote, a two-photon fluorescence microscopy system was built. At last, the two-photon fluorescence microscopy system is applied into the microscopy study of Rhodamine B specimen. The results show that in the same condition, two-photon excitation productivity is as much as 10⁵ times with an ultrashort pulse mode-locked laser compared with a CW laser. By using the UPLSAPO60XO objective, the saturation power is 50 mW while the radial and the axial resolution reach 303 nm and 727 nm. The image ability of the system is proved by the results, and the actual radial resolution is less than 3 μm.

Abstract:The relative position and attitude coupled second-order sliding mode controller is proposed by combining twisting algorithm with linear compensator for on-orbit servicing to a non-cooperative target spacecraft. On the basis of a coupled relative motion model between docking ports on two spacecrafts, the modified twisting controllers with linear compensation items are designed by using two different sliding surfaces. A strict Lyapunov function is proposed to prove that the modified twisting controllers have the property of finite time convergence for bounded perturbations and the upper bound for the time convergence is estimated. Simulation results are presented to validate strong robustness of the proposed second-order controllers for model uncertainties and limited perturbations with the comparison with the standard twisting algorithm. The chattering alleviation and attenuation is also achieved in actuating mechanism.

Abstract:In order to obtain the characterization of AC driven low-temperature plasma initiating the detonation combustion, single-trial detonation has been ignited by low-temperature plasma using acetylene as fuel and the air as oxidant in a 1.5 m long detonation tube and with 60 mm inner diameter. The air and acetylene were filled in the tube according to Dalton law of additive pressure. The air and acetylene would be mixed uniformly by circulating pump. The discharge time of the AC driven low-temperature plasma igniter was 0.5 ms and the energy was 0.2 J once. Meanwhile, propagation characteristics of flame and pressure wave were measured by ion probes and pressure sensors. The experimental results indicated that low-temperature plasma ignited detonation combustion successfully in the mixture when the excess air coefficients were 1.0 and 0.6; the peak pressure values of detonation waves reduced as the initial pressure and the excess air coefficient went down, meanwhile the DDT (Deflagration to Detonation Transition) time and distance increased. Detonation waves cannot be generated in the detonation tube when the excess air coefficient was 1.4.

Abstract:In order to represent causal relationship when relevance measure is used in statistic inference methods to filter gene pair, inspired by the research that casual-effect orientation algorithm can identify direction of causal-effect variables effectively,we propose an additive noise model based on the gene regulatory network construction algorithm by using additive noise model orientation algorithm to measure degree of causal relationship. The algorithm extends additive noise model based orientation algorithm to a feature selective algorithm, and builds ANM model of transcription factors set and each gene to select transcription factors of gene. In the experiments of three datasets DREAM5, the method has clear improvement in comparison with other algorithms, and could be used as an efficient algorithm to build gene regulatory networks.

Abstract:To solve the problem that the calculation accuracy of the robust principal component analysis is reduced when the high dimensional data is disturbed by the sparse large noise and Gaussian noise at the same time, this paper proposes the advanced augmented Lagrange multiplier method for the robust principal component analysis. On one hand, we enhance the calculation accuracy by the advanced method which is based on the optimal initialization of the Lagrange multiplier. On the other hand we propose a dual noise convex optimization model for the robust principal component analysis. As the experimental results shown, the proposed advanced method provides an optimal multiplier for the augmented Lagrange multiplier method and enhances the calculation accuracy of the method. Besides, the proposed dual noise model can separate the Gaussian noise and sparse noise from the data clearly and reinforces the robustness of the robust principal component analysis facing with dual noise.

Abstract:To improve dissemination toward all directions and decrease duration that message is forwarded, in this paper, the multi-hop broadcast for warning protocol in urban VANETs is proposed. The roads which wireless signal cover every time areclassified into four directions:east, south, west and north. Relay node at the intersection is decided by following rules: first, it has at least two neighbor nodeswhosedirections are different to the relay node, and the distances between relay nodeand the neighbors are more than the width of road.Second, its ID is the smallest among the nodes at the intersection. Relay nodes at intersections prioritize to forward messages without waiting. Relay nodes on the road are selected according to waiting-time equation and message is rebroadcasted if waiting time ends.MBW supports that message is propagated in both directions along the road. Due to relay node selection strategy, the number of relay nodes and message retransmissions is decreased. Simulation results show that MBW offers better coverage, lower delay, lower forwarding nodes ratio and lower overhead compared to exiting broadcasting protocols in VANETs.

Abstract:In order to improve the performance of signal detection algorithms in spatial modulation systems, we propose an intelligent signal detectionalgorithm and its improved algorithm based on particle swarm optimization. Efficient signal detection can be achieved by using particles' intelligent searches. Unnecessary local convergence can be avoided by designing weight coefficients for traditional velocity updating formula to improve its performance. Convergence and complexity are analyzed and simulations with different antenna numbers and modulation schemes are executed. Results show that the improved algorithm excels the particle swarm optimization in bit error rate, convergence and computing complexity, all these make it an appealing detection method for spatial modulation receivers.

Abstract:Based on the analytical Bit Error Rate (BER) upper bound of Spatial Modulation (SM) systems, the optimal configuration of SM by allocating properly of the information bits onto spatial and signal constellation diagrams is investigated. The analytical BER upper bound of SM systems is derived by employing the moment generating function method. The tightness of the upper bound is verified by a comparison to Monte-Carlo simulations. The antenna number and modulation order of SM systems are optimized based on the upper bound of analytical BER. It is shown that, the Quadrature Phase Shift Keying (QPSK) signal mapping is the optimal constellation in SM systems in terms of BER. Also, a SM system with a given signal constellation can increase the transmission rate without sacrificing BER performance and adding Radio Frequency (RF) chains by increasing the number of transmit antennas.

Abstract:To solve the problem of pulse shaping with arbitrary up-sampling rate in the high speed digital communication system, a new general high-speed algorithm based on look-up table is proposed, which can flexibly change sample rate. The algorithm uses FIR filter structure to realize arbitrary and flexible up-sampling rate conversion within in a range, by mapping different sample-rate conversion to the address problemof look-up table. Meanwhile, the proposed algorithm combining with pipeline structure and improved full parallel distributed arithmetic (DA) realizes the pulse shaping filter function at high speed, which is also validated through hardware platform. The proposed algorithm not only occupies less resource, but also implements at high speed with strong stability. In addition, the algorithm can flexibly realize arbitrary up-sampling rate conversion within a range.

Abstract:For high strength fiber airship envelope, a mesostructure model based on link model was built to explore its tearing propagation behavior by considering the friction and adhesion between the warp and weft yarn bundles. Tests with different length, location and angle incision crack specimens were carried out to observe the tearing propagation behavior which resulted in the tear propagation data under tensile tearing instruments. Combined with the mesosopic model and tests data, tearing propagation of the envelope material was simulated via Matlab to verify the model validity and obtain the max tearing values, which are in consistency with the tests, verifying the validity of the model and providing a new method to analyze the envelope tearing propagation behavior and predict the corresponding tearing values.

Abstract:Spatial modulation is one of the alternative physical layer technologies in 5G cellular communication system. To study the influence of LLL algorithm and augmented lattice reduction on the bit error rate and computational complexity of spatial modulation, two schemes are proposed, which are called LLL aided MMSE detection scheme and augment detection scheme. With different modulation symbols and different antenna numbers, the error rate of the two detection schemes is compared by simulation. Then, the computational complexity of the two detection schemes is compared by the matrix operation analysis. To make the analysis result more intuitive, the simulation with different antenna numbers is executed. Theoretical analysis and simulation results show that in the aspect of bit error rate and computational complexity, the augment detection scheme excels the LLL aided MMSE detection scheme. Therefore, the augment detection scheme is more suitable for spatial modulation technology.

Abstract:When the ideal frontier is discontinuous or inhomogeneous, the multi-objective evolutionary algorithm can’t solve multi-objective problems effectively by decomposition. In order to improve this situation, a novel multi-objective gravitational search algorithm based on decomposition (MOGSA／D) is proposed. In MOGSA／D, the multi-population serial strategy is good for the population study evolutionary information. According to shape prediction of ideal frontier, a suitable generation method of weight coefficient is selected. A pruning strategy is adopted to prune the solution set. Experimental results show that MOGSA has a good performance to solve multi-objective problems in comparison with other multi-objective optimization algorithms.

Abstract:To solve the problem that traditional sorting methods can not effectively deal with multimode radar signals, a new signal sorting method based on date field and hierarchical clustering is proposed to avoid the appearance of increasing-batch phenomenon when sorting multimode radar signals, and then a new algorithm based on cloud model used to evaluate the effectiveness of sorting results without database of radar radiation source is presented. The proposed algorithm is verified by simulations.

Abstract:A hyperspectral image band selection algorithm based on artificial bee colony algorithm isproposed to reducespectralredundancy of hyperspectral remote sensing image and computational complexity.Firstly, accordingtothecorrelationcoefficientmatrices among bands some pretreatments have been taken too btain the band sub space with less relevance. Then, neighborhood search has been implemented on each sub-space by using artificial bee colony algorithm together with the weighted sum between JM distance and OIF as the fitness function.To obtain the optimal band combination,the search is updated until the algorithm is convergent. Finally, the proposed algorithmis used to compare with band selection methods based on ACO, PSO and APO. The experimental results show that the proposed algorithm can not only ensure a good convergence but also reduce the computational cost. Simultaneously, when the obtained bands combination is used for hyperspectral image classification, higher classification accuracy can be obtained.

Abstract:To handle the difficult task of setting the relative parameters properly in the research and application of Pulse Coupled Neural Networks (PCNN), an improved PCNN algorithm is proposed. It uses the maximum between-cluster variance function as the fitness function of bacterial foraging optimization algorithm, and adopts bacterial foraging optimization algorithm to search the optimal parameters, and eliminates the trouble of manually setting the experiment parameters. Experimental results show that the proposed algorithm can effectively complete document image segmentation, and result of the segmentation is obviously better than the contrast algorithms.

Abstract:An implementation scheme of dual polarized millimeter wave microstrip patch antenna with broad bandwidth is proposed. The impedance bandwidth is broadened by employing coplanar parasitic patches and spatial parallel parasitic patches. The pair-wise anti-phase technology is used to design the 2×2 array antenna. The impedance bandwidth of the proposed antenna is 6.13% at the center frequency of 37.5 GHz with the isolation larger than 30 dB.The cross-polarization is -23.6 dB and the gain of the antenna is 11.5 dBi under the criterion of VSWR less than 2 . The proposed dual polarized microstrip antenna has promising features in terms of broad impedance bandwidth, high isolation between the input ports, reduced cross-polarization and high gains. The performances can meet the general requirements of the engineering dual polarized millimeter wave antenna.

Abstract:In order to reduce the area of solar cell, minimize the size and cut down the cost of the concentrator solar system, the partitioning method is adopted to design a Fresnel lens with high efficiency, short focal length and high concentrator ratio. The large round or square size Fresnel lens is separated into three parts: the central area, refractive area and total refractive area, and the computational equations of partitioning method are derived. A Fresnel lens is designed through this method, whose focal length and diameter ratio is 0.75 and concentration ratio is high up to 1000. TracePro simulation shows that the light concentrating efficiency of the designed Fresnel lens can be up to 88.75％. The Fresnel lens designed through partitioning method possesses the advantages of high optical efficiency, high concentration ratio and short focal length, and the cost and weight of concentrator solar cells system can be reduced.

Abstract:To explore the effect of narrowband interference suppression on carrier phase measurement zero value for satellite navigation system,this article establishes the equivalent filter model for classic NBIsuppression algorithm, and presents a study in order to analyze the effect of NBIsuppression on Carrier Phase bias.Then, the articlebuilds an analysis model of carrier phase zero value in the introduction of the NBIsuppression, works out the relationship between the carrier phase zero value bias and equivalent filter, and shows a condition for the unbiasedness of carrier phase measurement zero value. It is shown that linear phase filter has no effect on carrier phase zero value. Nonlinear phase filter has an effect on carrier phase zero value, which isdirectlyrelatedtothefilter weights. Based on the Monte Carlosimulation, thebiasvalue of carrier phase measurement zero value, which is simulated in the different parameter of the narrowband interference by using classic narrowband interference suppression algorithms, is obtained.

Abstract:In tightly-coupled Inertial Navigation System(INS)／Global Position System(GPS) systems, the filtering precision of Kalman filter (UKF) will be affected seriously by the calculation rounding error leading to the covariance matrix negative definiteness and the time-varying measurement noise in practical application. To deal with this problem, an adaptive square root unscented Kalman filter(NASRUKF) based on fuzzy control theory algorithm is proposed. This algorithm not only can ensure the covariance matrix non-negative definiteness, but also can track and adjust the time-varying measurement noise. Experimental results show that the algorithm has a good adaptability for the time-varying noise with higher accuracy,which makes the system have higher stability and robustness in comparison with UKF algorithm.

Abstract:To solve the forming die' s early failure of 7A60 aluminum cup in the twist-pressure isothermal composite formingexperiment,withthe use of finite element software DEFORM, a detailed discussion and analysis of the cause of failure is studied in terms of the technical characteristics, stress distribution and mold structure. The results show that the main reasons which cause the early rupture at the corner of the die arethe stress concentration, hot-cold cycle thermal stress and the oxidation of high-temperature mold. Then based on thetheory of “no crack first division”, the structure of the die is improved. Finally, the results show thatthe improvements of die effectively avoid the stress concentration and reduce the equivalent stress extremes by 30%.The metal flow lines are visible on the surface of cup with no obvious defects.

Abstract:To explore the effect of different heat treatment temperature on structure and electrochemical performance of electrode material(TiO₂/AC) prepared by sol-gel method, Scanning Electron Microscopy (SEM), thermal gravimetric analysis (TG-DTG), Brunauer-Emmett-Teller gas adsorption method (BET), X-ray diffraction (XRD) and electrochemical workstation are introduced to analyses the micro-structure and electrochemical performance. The results show that the crystal anatase TiO₂ nanoparticles were attached to the surface and pores in the activated carbon by heat treatment. With the increase of temperature, the specific surface area increased first and then decreased. Moreover, the crystal form changed from anatase to rutile and grain size increasing gradually, and the specific capacitance of corresponding electrode increased first and then decreased. When the temperature was 450 ℃, crystal form was anatase ; the grain size, effective specific surface area and electrochemical performance were the best.

Abstract:The study aims at providing recommendations for resource allocation of disaster prevention and mitigation in rural areas. Focusing on disaster performance forms and based on disaster data collection and statistics closely linked with rural residents' production and living, firstly the main types of disaster were determined by representing the proportion of households affected by disaster. Then, taking the potential investment relations of government and villagers, two main bodies in responding to disasters, as a premise, and winter disaster as an example, a relational model of disaster influence universality by multiple linear regression was constructed. Last, the corresponding methods and strategies about disaster prevention and mitigation for rural areas in cold regions were put forwards.