Abstract:Aimed at high strength, durability requirements of airport pavement concrete, by adding Na2SiO3 and NaOH complex activator in slag, self-compacting alkali-activated concrete (AAC) is prepared with slump 160 mm and upwards, flexural strength 7 d and 28 d respectively reaching 7.6 MPa and 8.5 MPa. Its durability, distortion, construction and economy performances are also studied by comparing with porland concrete. The results show that the anti-permeability, anti-frozen, corrosion resistance and abrasion resistance of SCAAC are superior to the porland concrete, and its anti-permeability rank exceeds S40, anti-frozen rank exceeds F300, sulfate resistance and abrasion are excellent. The Alkali-activated concrete is of low deformation concrete but with ratherish great early deformation, therefore early keep should be reinforced. AAC can meet the requirements of airport pavement in workability, strength, durability, constructing and economy,and it can be applied to the construction of airport pavement.

Abstract:Inverse simulation is important in validating the known flying state. In the process of establishing equations, quaternion is used to set up six degree-of-freedom(6-DOF) flight model in order to avoid singularities，the flight simulation based on quaternion is also performed. The general method of inverse simulation is introduced; the means of identifying key parameters in the inverse simulation is discussed. The 3-DOF model trajectory acquired by avoiding a missile is inversely simulated to get the control rule for producing the initial trajectory, the inversely simulated trajectory is gained by running the 6-DOF model with the obtained control rules. The rationality of the initial optimal trajectory is verified by comparing the inversely simulated trajectory with the initial trajectory.

Abstract:Because of aging, the structure state and mechanical property of HTPB composite solid propellant will change during the storage. These results have bad effects on the structural integrity of propellant grain and the service life of rocket motor. In view of this problem, many scholars have developed a large number of researches. In this paper, the related research progress in this field both at home and abroad are reviewed from analyses and experiments. The achievements and problems on the research are analyzed and reviewed emphatically. Direction, key point and the way of future research in this field are pointed out. Since HTPB propellant is regarded as a high polymer filled with a kind of solid stuffing, its structure state is closely related to mechanical property. The research on the correlation of its structure state and mechanical property from the chemical structure, network structure and is microscopic structure and etc. is of great benefit to revealing failure cause of chemistry-mechanics correlation of HTPB propellants.

Abstract:The shape parameter in Radius Basis Function (RBF) determines RBF's ability of approximation. Aimed to improve the ability, the error function of RBF is build, and then the shape parameter is chosen by optimization of the error function. The results of test functions show that the algorithm proposed here is much more adaptable to higher dimensional problems than Kriging model. Compare with Kriging, when the present algorithm is used in building Response Surface of wing structure, better approximation results are obtained in the computation of the mass of wing, the maximum stress of skin and the front edge displacement of wing. The effectiveness of the algorithm is further verified at the same time.

Abstract:It is an important problem how to effectively transform the information of time and attitude into aircraft's expectation control command of velocity and attitude on condition of taking UCAV's performance constrains into account. This paper presents a new method which apply maneuver movement matching planned path by establishing maneuver action database to create the expectation commands such as thrust brake gate, perpendicular load, flight path angle and flight path bank. The UCAV's performance constrains are taken into consideration in the design of the method, so the created expectation commands are reasonable and easy to be realized. The results of simulation show that the method has a good real-time and the created command is easy to be followed.

Abstract:Flow fields of 2-D vectoring nozzle at different jet angles are calculated by the finite volume method based on 2-D Reynolds average N-S equation and RNG κ-ε turbulent model. The results show that the effective throat area of the nozzle is reduced as the jet angle is closed to 0°. Compared with the case without jet, the relative throat area ratio of the nozzle can achieve 78.15％ in the case of the jet location 29.5, width 1 mm, angle 0° and RSP=1.0. If RSP is kept unchanged, the coefficient of the total pressure recovery, thrust coefficient of the nozzle and the jet mass flow will approximately keep in a same level at different jet angles. The throat area of the nozzle can be effectively controlled by changing the jet angle.

Abstract:A beamed scan technology is proposed for small IFOV of a missile seeker. Three typical scan graphics of S figure, Z figure and line-by-line helix scan are researched in a contrast way. Based on the synthetic analysis of scan period and detection probability, line-by-line helix scan is chosen as the beamed scan mode. A mathematical model of angle-scheduled loop is established and a dual-module fuzzy PID controller is designed. The angle-scheduled loop is simulated to effectively control the seeker. A mathematic model of dual-model controller of Fuzzy-PID is established. Finally, when target-indicating angle is at 1°, system simulation is conducted with step input. The results show that the dual-module fuzzy PID controller has the advantage of small over shoot, high static accuracy and short response time, which meet the requirements of the system and realize beamed scan control.

Abstract:The problem of observability for bearings-only target tracking is discussed in this paper based on the target traveling in the three-dimensional space at a uniform velocity, constant acceleration and first-order lag acceleration. Pseudo measurement equations are constructed, Grammian criterion of linear system theory is used, and the problem of solving complex nonlinear differential equations is avoided, the method can be used to deal with the general situation, and is not restricted to Nth order target dynamics. The analysis of the necessary and sufficient conditions shows that some types of observer maneuver do not satisfy the condition, the maneuver order of observer is not necessarily higher than that of the target, this conclusion is different from the previous ones. The method adopted in the paper is also effective to the general bearings-only measuring problem.

Abstract:Based on the idea that PBG can restrain the promulgating of surface wave in substrate, a novel patch antenna is designed with multi-layer in order to enhance the gain. Through loading the PBG structure, 11.54 dB gain of element can be achieved. Compared to the patch antenna with single layer, 8.68 dB is increased. Then a planar array fed by parallel net with 4×4 elements is manufactured and tested. The experimental results show that VSWR is less than 2.0 from 12.0 GHz to 13.0 GHz, and 22.23 dB gain can be achieved at 12.5 GHz, which is approximately doubled in comparison with the common array. Such planar array will be used extensively in the field of miniaturization for satellite reception.

Abstract:This paper discusses the problem that the cracks the coating of aircraft result in the variation of the medium performance index and thus affect the stealthy performance of aircraft. By using Ansoft Designer based on MOM and resolution methods, the calculation and analysis of radar X-band frequency wave high frequency electromagnetic characteristics are done when the medium parameter variation caused by cracks appear on the coating sinter ferrite stealthy layer of a perfect conductor disc base. By using V polarization wave incidence and H polarization wave incidence in calculation and analyses, the result shows that the infection is obvious on the stealthy electromagnetic performance because of the coating sinter Ferrite medium performance variation caused by cracks in 8-12 GHz.

Abstract:In order to store and transmit largely and efficiently, SAR images must be compressed effectually. The traditional coding method of SAR image based on wavelet translation can only be used to decompose low frequency, so a lot of information of intermediate/high frequency is lost. In view of the above problem, this paper presents an adaptive SAR image compression algorithm based on wavelet transform. In this paper, the speckle noise is reduced to improve the image quality first. And then according to the energy index, the SAR image is decomposed into a series of subbands, which have different significances. Finally, all the subbands are quantized by the minimal error quantization at the same bit rate. The use of the algorithm can protect the high frequency details of SAR image adequately, and can achieve a better compression result.

Abstract:With the widespread use of satellite navigation technique, the requirement of the precision and effectiveness in particular of navigation is more and more strict. To guarantee the requirement, the method of RAIM is addressed. The superiority of the method has become more and more apparent. The common methods of RAIM include the comparison of pseudo-range, the LSE and the Parity method. In this article, the novel method is studied and simulated. The graphic and numeral simulation results adequately demonstrate that the method is feasible.

Abstract:Modulation hopping technique is a new kind of anti-interception technology against modulation recognition by shortening the duration of each modulation and keeping modulation hopping in pseudo-random way. In order to capture modulation-hopping signal effectively and rapidly, a dual-dwell parallel acquisition approach with code matching is proposed, and the acquisition performance is analyzed. This approach is used to realize modulation classification by matching modulation identification code and make synchronization acquisition by dual-dwell parallel approach, and finally ensure good performance on the condition of low SNR and few signal symbols. The analysis results verify that the approach has higher modulation recognition rate and shorter average acquisition time on AWGN channel. However, the performance on Rayleigh fading channel is relatively poor; in such case, the use of an improved RAKE-based method can effectively enhance the performance effectively.

Abstract:Aimed to ensure the correct transmission of most important data in case of the channel's performance deterioration, this paper presents a novel unequal error protection scheme based on LT codes. Firstly, the UEP performance deterioration of the alternative UEP scheme, which is caused by the simple rounding operation, is analyzed, and an improved scheme that can avoid the UEP performance deterioration is proposed. In this scheme the bidirectional rounding operations according to different probabilities in degree computations of most important bits are introduced, and the fixed degree skew coefficient is revised to a function of priority and degree of output nodes. Then the upper and lower bounds on the ML decoding error probabilities of MIB and LIB over the BEC are deduced. Finally the UEP performance on the BP decoding over erasure channel is simulated. The theoretical deduction and simulation results show that the proposed UEP scheme has better UEP performance and more flexibility in code design than the alternative UEP schemes.

Abstract:With the coming of 3G Age, the new mobile communication network is building in all-round way. Especially the indoor network construction is more complicated and important. To solve the problems about the network overlays and the cost of the construction, this paper presents a kind of broadband omnidirectional indoor antenna for the third generation mobile communication system. The proposed antenna is of an asymmetrical biconical structure. Based on theoretical analysis，the structure sizes of the antenna have been changed and optimized by HFSS. Its voltage standing wave ratio(VSWR) is less than 1.4 within the frequency range of 800 MHz-2 500 MHz. The gain is more than 2 dBi in low frequency and 5 dBi in high frequency. The antenna can meet the requirements of the wireless broadband communications for 2G and 3G systems, thus the cost of construction for indoor communication is reduced effectively.

Abstract:In order to optimize the design of equipment, and reduce the investment in experiment expense, a large eddy simulation method coupling with 2-D unsteady VOF model is adopted to simulate the gas-liquid water-jet in and around the nozzle of pulsed anti-riots water cannon. After the setting up of experiment tape, the high-speed photography technology is adopted to photo the water jet around the nozzle, and then the velocity reader software is used to gain the velocity of the outside water-jet. Compared with the numerical result, the obtained experiment water-jet figure and velocity are in better accord with the simulation results. By using the said method to do the simulation of changing numerical parameters, the initial pressure has significant influence on the velocity of water-jet, but the initial launch angle has little influence on the velocity of water-jet, which only affect the biggest cannon-shot. The study results show that with bigger initial pressure and smaller initial water quantity, bigger water-jet velocity and shorter launch time can be obtained. The conclusion achieved is of some guide sense to the optimization of design of water cannon.

Abstract:The situation of present network security is becoming rigorous day by day，the traditional security technologies such as firewall, intrusion detective system have some kinds of defects, that is, they cannot identify the unknown intrusion pattern effectively, the honeypot technology as a proactive defense method also has its own limitations. As to the defaults of the above every single technology and from the angle of active defense, the paper builds up an Intrusion deception architecture based on network active defensive security model, and simultaneously designs an interface system among the honeypot, firewall and the IDS to overcome the default that the firewall can not perform unreal time detection. This can decrease the false alarm and leaking alarm of IDS, make up the deficiency and unleash the superior of each method, thus, the proactive defense capacity of the network systems is enhanced. The paper also gives out a finite state auto-machine model, simulates the basic functions of the intrusion deception system, which provide a theory and reasoning supplement for the system's action description and architecture design.

Abstract:According to the theory of the equivalence between the independence and the uncorrelation of two random variables, which only need two values, a joint probability distribution's integrated expressive form is found. Through extending the theory to multidimensional joint probability distribution of two states, a multidimensional description is multidimensional is discovered. If marginal distributions of all random variables are written down, the range of each correlative coefficient can be calculated and then the joint distributed matrix can be found. The validity of this method is verified through simulations. By the way, this is applied to the description of joint channel from data communications and a highly fine conclusion is achieved.

Abstract:To improve on the ability to efficiently explore and approximate large subspaces of the multidimensional input variable models, find out the orthogonal and uniform combining point in experimental design, reduce the complexity of the experimental design algorithm, this research develops a new set of experimental designs for metamodeling. The traditional experimental designs are of orthogonal experimental design and uniform design, but the orthogonal experimental design has poor space-filling and the uniform design has a big correlation. The paper combines orthogonal Latin hypercube and uniform designs to create the designs with near orthogonality and excellent space-filling properties based on multiple measures. By using the method the nearly orthogonal experiment with eight to eleven variables is designed, each of which has thirty-three levels, to testify the nearly orthogonal experimental design. Through comparison and analysis, the results show that the nearly orthogonal experiment designed by this method has near orthogonality and excellent space-filling properties. So this method is feasible and of significance in improving the effect of computer experiments

Abstract:With the development of science and technology and environment, lead-free piezoelectric ceramics has been a necessary trend, and potassium-sodium niobium (KNN) based lead-free piezoelectric ceramics has become a hotspot because of its high Curie temperature and piezoelectric properties. This paper firstly summarizes and analyzes the study direction and actuality of potassium-sodium niobium (KNN) based lead-free piezoelectric ceramics from new component, ions substitute, sintering reagent and temperature dependence in recent years, and then indicates the future hotspot and problem. We think it can improve the temperature stability to introduce diffusion mechanism into KNN based ceramics. Meanwhile, we also should study the effect of nano-sized domain on properties of KNN ceramics. At last, the paper forecasts the future study direction——the study of electric properties, of temperature stability and micro mechanism.