Abstract:The high-aspect-ratio composite wing is generally used in long-endurance Unmanned Aerial Vehicle (UAV), which uses lightweight and high-specific-strength composite structure. This type of wing has significant geometric nonlinearity and aerodynamic nonlinearity during the flight, which further leads to the aeroelastic nonlinearity of the wing. There is a huge difference for design analysis method between the high-aspect-ratio composite wing and the conventional wing. In order to summarize the research status and forecast the future research direction of the high-aspect-ratio composite wing, this paper analyzes and summarizes the design, analysis and experiment methods of the existing high-aspect-ratio composite wing. The aeroelastic characteristics of wing would be affected by the geometric and aerodynamic nonlinearities. The structural design and structural analysis methods of high-aspect-ratio composite wing are introduced. Two kinds of aerodynamic analysis methods are introduced: the aerodynamic analysis method based on the strip theory and binary unsteady aerodynamic method and three dimensional aerodynamic analysis method considering spanwise flow effect. Static aeroelasticity method, dynamic aeroelastic analysis method and active control technology applied in the high-aspect-ratio wing are introduced. The recent advance in aeroelastic tailoring of high-aspect-ratio composite wing is analyzed. Finally, the experimental research progress of high-aspect-ratio composite wing is introduced. Based on the literature analysis, it can be seen that the structural model of the existing high-aspect-ratio composite wing adopts the equivalent beam plate model, while the aerodynamic model adopts the combination of the strip theory and the binary unsteady aerodynamics considering the dynamic stall. The flight test, as well as the research based on the coupling of aerodynamic reduced-order model and the structural model of the high-aspect-ratio composite wing may be the research and development directions of the high-aspect-ratio composite wing in the future.

Abstract:A multiple homotopy method is proposed to optimize the very low thrust fuel-optimal transfer trajectory under the effects of J2 perturbation. A simple problem of high thrust, energy-optimal transfers in the linear gravity without J2 perturbation is constructed as the homotopy initial problem. Three homotopic parameters are embedded in the kinetic equations, thrust magnitude and performance index, respectively, and the optimal control laws in the homotopy process are deduced according to the minimum principle. By solving the subproblems with iterative homotopic parameters, the high thrust energy-optimal transfers, low thrust energy-optimal transfers and fuel-optimal transfers are solved in turn. A numerical example about rendezvous mission of satellite and debris on sun-synchronous orbits is given to substantiate the effectiveness of the method in fuel-optimal low thrust trajectory design in the gravity with J2 perturbation. Using the proposed method, the difficulties of the highly nonlinearity of the dynamic system caused by J2 perturbation, the fuel optimal problem's discontinuous structure of Bang-Bang control and many revolution transfers can be solved.

Abstract:To obtain both good performance on both aerodynamic and stealthy, integrated design and analysis on aerodynamic and stealthy characteristics for flying wing unmanned aerial vehicle(UAV) is conducted based on stealthy inverse design method, focusing on the big bump in the fuselage of twin-engine layout flying wing UAV. Then a kind of fuselage with leading edge similar to eagle mouth is proposed, whose leading edge radius of airfoil is decreased. Using computational fluid dynamics (CFD) method, the numerical simulation is verified on M6 wing. Physical Optics (PO) and Multilevel Fast Multipole Method (MLFMM) are chosen for numerical study on the stealthy performance of cylinder and a certain scale model of flying wing UAV. Moreover, the verified methods are applied to study the aerodynamic and stealthy characteristics of flying wing UAV. The results show that the aerodynamic and stealthy calculation result is close to the experiment data, indicating that the numerical simulation method is valid. Not only the longitudinal aerodynamic performance of flying wing UAV with fuselage leading edge similar to eagle mouth increases appreciably, but also its stealthy performance improves significantly in the forward direction with the azimuth angle from -25°~25°. In addition, it indicates that the stealthy inverse design method is effective. The design with leading edge similar to eagle mouth mainly affects the pressure distribution of fuselage, and it is helpful to advance the lift/drag characteristic. At the same time, the stealthy performance of the optimize design is better than the traditional blunt leading edge at different frequencies and rolling angles.

Abstract:At the on-orbit servicing final approach stage, the traditional monocular vision navigation method is limited by the camera field of view, and artificial feature markers cannot be placed on the non-cooperative target. To overcome the drawbacks, a vision navigation algorithm based on part of the solar array triangle support of non-cooperative spacecraft is proposed. Firstly, a "selfie stick" camera installation structure and a real-time camera calibration scheme are designed, and then the method of calculating the camera installation angle is provided. Next, the optimization model satisfying the real geometry structure of the triangle support is built based on the adverse projection theory. Then, the ant colony search algorithm is applied to solve the depth and the absolute position method is applied to calculate the relative attitude and position. Finally, the mathematical simulation in the background of on-orbit servicing final 2 m~0 m approaching of non-cooperative spacecraft is carried out. The simulation results show that the relative attitude and position determination accuracy are better than 0.2° and 3 mm when the relative distance is less than 1 m, and it proves that this algorithm is effective and feasible. The simulation results have proven the feasibility of the relative navigation scheme, and indicate that the proposed algorithm has high accuracy, which increases with decreasing relative distance between the servicing and the target spacecraft. Furthermore, the algorithm has good robustness to the measurement errors of projection points, and keeps the accuracy for relative large measurement errors.

Abstract:The augmented flight dynamic model for trajectory optimization is built to improve the optimal control strategy of trajectory optimization for tilt-rotor aircraft landing in short takeoff after one engine failure. The longitudinal rigid-body flight dynamic model is augmented with a set of algebra equations describing the relationship between the aerodynamic forces and controls in the cockpit, and a set of differential equations describing the control rates to avoid jump discontinuities of controls in the trajectory optimization. The trajectory optimization problem is transformed into a nonlinear programming problem and solved by a sparse sequential quadratic programming. The XV-15 tilt-rotor aircraft is taken as a sample for the investigation. The optimal solutions are calculated and compared with those obtained in the relevant reference. The results indicate that the augmented flight dynamic model can provide more longitudinal control information such as the collective control input, the root collective pitch, the longitudinal cycle pitch and the rates of control variables. In addition, the time histories of power required, thrust coefficient and longitudinal stick are more relatively gentle. Therefore, the presented method can provide pilots more useful references to perform the landing procedure.

Abstract:There are complex rotor/rotor/ground interference effects when a coaxial-rotor helicopter hovers near ground. A computational method based on free-wake model is developed to analyze the flow field and thrust of coaxial-rotor helicopter in ground effect. Firstly, the lifting-surface blade model and the ground panel model are taken in this method to simulate the effects of blades and ground to the flow field. A 3^rd-order accuracy time-marching scheme is conducted to get the free-wake of coaxial-rotor. Also, the constant-volume-rectification method is incorporated to prevent numerical divergence. Then, the coaxial-rotor out of ground effect (OGE) and the single-rotor in ground effect (IGE) are used as examples to validate the method. Finally, based on the examples, the features are analyzed, including the characteristics of wakes and flow field, the distribution of velocity and thrust in rotor disk plane, the interference effects between two rotors and the gain of thrust. Calculated results show that the wake rolls up and expands radially in ground effect when hovering, besides the induced velocity in rotor disk plane is connected with upper rotor, lower rotor and ground. The results show that ground effect causes the more uniform distribution of induced velocity and thrust along the rotor. Besides, the gain of thrust for coaxial-rotor is higher than that of a single rotor when the power is kept the same.

Abstract:To analyze the muzzle flow field of hyper-velocity projectile, we established a 2-D axisymmetric numerical simulation model based on the finite volume method. The Navier-Stokes equations are solved on an extended mesh covering the whole computational domain. The holistic movement of a partitioned mesh processing method and realizable k-epsilon turbulence model is used coupling the process of interior ballistic and the Six-DOF UDF program which controls the projectile moving. Taking the 300 mm balanced gun as an example, the simulation results indicate here that the initial flow field has been formed clearly when the projectile is 3.3 m away from muzzle, and the pressure is about 3.8 MPa when the shock wave gets to the muzzle. It is noteworthy that the propellant gas velocity reaches 2 500 m/s but it is still unable to catch up and surround the projectile. So the impact of muzzle flow on the hyper-velocity projectile movement is different from the impact on the low-speed projectile. Subsequently it is formed a completely wave system composed of the multilayer shock wave including coronary blast, shock wave, reflected shock wave, Mach disk and the discontinuity surface, which makes the wave structure and the jet flow field more obvious.

Abstract:To get a better de-noising effect, a novel noise reduction method combining the sparse decomposition with lifting wavelet transform is proposed. Firstly, the error model is established for the MEMS gyroscope output signal with noise, and wavelet coefficient of signals with noise can be obtained by lifting wavelet transform. Then the sparsity of the coefficient is recovered according to sparse decomposition theory. Finally, signals are reconstructed by lifting wavelet inverse transform, i.e. the de-noised signal is thus obtained. In addition, since the gradient projection algorithm is global optimal algorithm with high computational efficiency, the theory of gradient projection is used in the restoration of sparse signal. Specifically, a sparse decomposition based on gradient projection is designed to simplify the algorithm complexity and improve the stability of the algorithm. To verify the performance of the proposed algorithm, the static experiment and dynamic car test on MEMS gyroscope are implemented. The results show that the denoising performance of the new method is better than that of wavelet filter either under the static or dynamic condition, especially under the latter condition. Meanwhile, the CPU time of gradient projection is less than orthogonal matching pursuit (OMP) and basis pursuit (BP).

Abstract:When the RLV reaches the TAEM interface, the large-scale perturbation exists in initial position and azimuth angle states. A rapid trajectory planning method based on iterative correction algorithm has been proposed, to ensure that the RLV can get into the approach and landing interface successfully. According to the RLV's specific initial states, the method can select the direct or overhead heading alignment cone (HAC) mode automatically, and can generate a feasible reference profile quickly. First, the reference dynamic pressure-height profile can be generated based on the height and velocity constraints. Tracking the dynamic pressure-height profile is employed as the longitudinal guidance law, whereas tracking the ground track is used as the lateral guidance law. The longitudinal and lateral guidance laws ensure that the speed, flight path angle, azimuth angle, and lateral position of the RLV meet the terminal constraints. The ground track is composed by piecing together several flight segments that are defined by three geometric parameters. Two of the parameters, the position of HAC and its final radius, are determined by the iterative correction algorithm rapidly, until all of the required conditions for approach and landing interface are met. Simulation shows that the algorithm can select the direct or overhead heading alignment cone (HAC) mode automatically, and can generate a feasible reference profile quickly according to the RLV's specific initial states. The profile generation time are 4 to 12 seconds. The numerical methods used by the proposed algorithm are very mature and stable, and very easy to be realized in engineering. Compared with the strategy of the space shuttle, the algorithm does not rely on a number of reference trajectories that are calculated and stored offline, and the algorithm can a new reference trajectory autonomously according to the specific states. Simulation results have demonstrated the rapidity, robustness and practicability of the trajectory planning algorithm.

Abstract:The supersonic mixing layer formed by a planar thin hydrogen jet at 2.3 Ma and a 2.0 Ma surrounding airflow in a scramjet engine model is studied in order to investigate the growth characteristics with consideration of shocks. Flow field structure and features of the supersonic mixing layer are achieved by using large eddy simulation method with the OpenFOAM software. Reasonable agreements are obtained between calculation and experiment in terms of flow field structure and component distribution. The component concentration, the thickness, the compressibility effect and the total pressure loss are analyzed. Results show that four developing regions can be observed for the growth of the mixing layer. The expansion-fan/shock-wave pattern at the injector exit makes the convective mach number decrease dramatically, leading to a reduction in compressibility effects and a contribution to the development of the mixing layer. The interaction of shock/mixing layer results in local amplification of turbulence and gain of vorticity, which is beneficial to the supersonic mixing. However, the increasement in total pressure loss is unavoidable in the presence of shocks because they can bring performance losses of the scramjet. Thus a tradeoff between the enhanced mixing efficiency and the decreased total pressure recovery should be considered in the scramjet optimization design.

Abstract:In the deep space exploration, astronomical image acquisition, transmission and processing have always been the focus of research. To solve problems of slow convergence speed, poor denoising performance in compressed sensing iterative shrinkage-thresholding algorithm for image processing, an improved iterative shrinkage-thresholding astronomical image denoising and reconstruction algorithm with high performance is proposed. Firstly, the BB linear search stepsize of the classical steepest descent algorithm is used to accelerate the convergence speed of iterative shrinkage-thresholding algorithm; secondly, to further improve the reconstructed astronomical image quality, based on the classical VisuShrink shrinkage-threshold, a decreasing VisuShrink shrinkage-threshold is proposed to select the image information; since the pseudo-gibbs effect caused by threshold denoising method will appear in the process of image reconstruction, the cycle spinning method is finally employed to adjust the reconstructed image in each iteration. Multiple experimental results show that, compared with the traditional compressed sensing iterative shrinkage-thresholding algorithm, the algorithm proposed can not only obtain better denoising performance and faster convergence speed, but also effectively protect the astronomical image detail information, such as feature and texture. In addition, when compression sampling ratio is lower, the algorithm proposed also can obtain relatively higher peak signal to noise ratio and visual quality, proving the effectiveness of the algorithm proposed for astronomical image denoising.

Abstract:To accurately evaluate the wobble error of the rotary axis system, the relationships among the wobble error of the rotary axis system, installation errors of the reflected mirror and of the autocollimator, and the readouts of the autocollimator are established firstly. Installation errors of the reflected mirror are referred to be the first harmonic in the quadrature phase of the autocollimator readouts, and then the formation mechanisms of the first harmonic resonance are analyzed, which is represented as the first harmonic in the same phase. A separation method to handle the first harmonics in the same phase and in the quadrature phase are designed for the first harmonics in the x-and the y-direction readouts of the autocollimator. This method eliminates the first harmonics caused by the installation errors of the reflected mirror, and retains the first harmonic resonance in the rotary error. As a result, the data processing method of the wobble error of the rotary axis system is improved. Finally, by changing the installation errors of the reflected mirror, the wobble errors of the same rotary axis system are measured two times. It is proved that this separation method is correct since the first harmonic resonance errors from the two groups of the measured data are consistent. Meanwhile, it only eliminates the first harmonic caused by the installation errors of the reflected mirror, and retains the first harmonic resonance errors in the rotary errors. The experimental results show that the method of data processing for wobble error of the rotary axis system is more reasonable and accurate.

Abstract:In order to realize the high precision, digital and miniaturization of MEMS gyroscope, which is the application requirements of the field of inertial navigation and measurement, this paper designs and implements a practical MEMS gyroscope interface circuit which adopts the process of dual-chip integration, integrated based on N-well CMOS process of 0.5 μm. The paper introduces the design of analog front-end circuit which contains closed-loop self-exciting driving structure based on high-frequency carrier and low noise differential sensitive detection circuit. The high frequency signal modulates the sensitive signal to the high frequency and adds the flicker noise. Through the phase sensitive demodulation and low-pass filtering, the low noise analog angular speed output is obtained. The circuit converts analog signal into digital signal by an integrated high-resolution sigma delta four-order single ring one bit ADC, achieving an interface circuit of silicon gyroscope with digital output. Test results show that the dynamic range of the modulator which bandwidth and scale factor are 60 Hz and 46.45 LSB/(°)·s^-1, respectively, is up to 130 dB, and the measuring range of gyroscope is ±200 °/s. The linearity of the modulator with the noise of 0.004 (°)·s^-1/Hz^1/2 is 340×10^-6, and the stability of the zero bias is 3.4 °/h. It enables miniaturization, low cost and precise digital output of angular speed through integrated circuit. Comparison of the test results with other related research also confirms that the structure can achieve good performance.

Abstract:A bandgap reference is designed with high order curvature compensation method, which has advantages of simple structure, good energy dissipation capacity and an optimized temperature coefficient of the reference voltage. Taking advantage of the nonlinear characteristics between leakage current and gate-source voltage when NMOS is working in the sub-threshold region, the proposed method decreases the temperature coefficient of reference voltage by introducing a high order curvature compensation current of which the temperature coefficient is contrary to reference. The formula of the compensated reference voltage is derived. Based on the 0.18 μm BCD process, the simulation results show that temperature coefficient of reference is 6.94×10^-6 in the temperature range of -40 ℃~150 ℃, linear regulation rate is 0.033% in the supply voltage V_DD range of 2.5~5.0 V, the supply current is 7.36 μA with 5V power supply, the power supply rejection ratio(PSRR) is 77.4 dB at the Tipical corner(TT). The theoretical analysis results of reference agree well with the simulated results. The bandgap reference voltage source shows excellent performance vias the high order compensation, which satisfies the requirement of low power consumption and low temperature drift in bandgap reference designing.

Abstract:A design of controller for a quadrotor vehicle with one rotor failure is proposed based on back-stepping approach, to ensure the safety of vehicle when ordinary controllers are ineffective under one rotor failure. According to the rotational and translational motion equations of the quadrotor with one rotor failure, the controller is divided into inner and outer ring. An attitude control loop is adopted to perform the attitude tracking control, and a position loop is proposed to control the position of the vehicle. Although the controller sacrifices the controllability of the yaw state, the vehicle can reach position tracking, and achieve the near-hover flight state in which roll and pitch angles are zero and the angular speed around the vertical axis is a nonzero constant. The simulation results demonstrate the effectiveness of the proposed controller. The results show that the absence of controllability of the yaw state of the quadrotor vehicle will not threaten the aircraft security or its trajectory tracking. The study confirms that a quadrotor vehicle with a rotor failure is still controllable.

Abstract:Phased microstrip array antenna is an effective method to generate vortex electromagnetic beam containing orbital angular momentum (OAM), and a good design of the multi-mode OAM microstrip array antenna is crucial to improve the vortex performance. We consider circular microstrip antenna with coaxial feed as the element to compose the circular antenna array, which is excited with unit amplitude and equal phase delay from element to element. Two single-ring uniform circular array antennas are designed with the array elements number as eight and sixteen respectively, and a dual-ring uniform circular array antennas is designed with eight elements in inner ring and sixteen elements in outer ring. The OAM-carrying electromagnetic vortex can be generated at 15 GHz from both sing-ring and dual-ring uniform circular array antennas, and the vortex characteristics, such as radiation patterns and OAM modes, are analyzed in detail by using a full-wave electromagnetic field simulation code HFSS. According to the simulation and optimization, with the increase of elements number in the sing-ring structure, we get the better electromagnetic wave vortex performance at the cost of a larger size array antennas. In contrast, through using collaborative optimization simulation combined with inner and outer ring, the vortex properties of dual-ring structure is better than that of the single-ring structure at suitable array configurations and phase shifts.

Abstract:To seek key nodes and improve network robustness, the dynamic convergence complex network model and its node importance evaluation method are proposed for wired and wireless integrating layered networks. Considering characteristic of dynamic convergence complex networks, parameters including edge connection probability, path connection probability, network connection probability, convergence node proportion, convergence node distribution and convergence path proportion are designed. Based on node importance evaluation indexes in single-layer complex networks, the node degree centrality, node betweenness centrality and node convergence centrality in dynamic convergence complex networks are presented. Node convergence centrality of convergence nodes indicates their contribution to network convergence, and that of non-convergence nodes indicates their auxiliary effect to network convergence, especially they are used as relay nodes among convergence nodes. At last, node importance evaluation is implemented considering network topology structure and its dynamic convergence characteristic. Typical example results of improved dynamic convergence kite networks show that the proposed method can comprehensively depict the node importance in dynamic convergence complex networks. Simulation network composed of fiber communication network and satellite communication network is designed by NS2, further indicating the effectiveness of the proposed method.

Abstract:The complex network theory provides a new perspective in the study of operational network, a powerful method to investigate the relationship between network structure and function. To study the load-induced cascading failure of interdependent operational networks, two-layered asymmetrical interdependent network is constructed according to the interactive relationship of military system. Then, an improved "load-capacity" model based on local load redistribution is proposed to study the edge failure and load transfer, and the computation complexity of the cascading model. Thirdly, the influence of edge load and capacity on the cascading invulnerability is simulated under malicious edge attacks and compared with a WS-WS symmetrical interdependent network. The results show that the robustness against malicious attacks is positively related to the capacity, yet negatively to the load either in isolated or interdependent state. A short plateau appears in the progress of cascading due to the hierarchical weighted structure of C2 subnet under isolated status. The cascading invulnerability of asymmetrical interdependent operational networks is worse than the symmetrical one. The two subnets in the former network have different invulnerability performances, while the subnets in the latter system almost have the same performance.

Abstract:To investigate the influences of the empennages on the underwater projectile hydrodynamics, the paper established the numerical models of two high-speed supercavitating underwater projectiles which have identical dimensions except the empennages based on simplified Rayleigh-Plesset equation cavitation model and Shear Stress Transport (SST) turbulence model through solving the Reynolds Averaged Navier-Stokes (RANS) equations of mixture fluid and the mass transport equations between each phase. The projectile′s drag characteristics and supercavitation morphology variations were calculated, analyzed and compared within the identical initial velocity. The results show that the two kinds of projectile models can quickly form stable natural supercavity when moving underwater with a high speed; the impact of the empennages against the cavity surface destroys the original circle cross section of the supercavity and forms a bulge. The drag coefficient of the projectile with empennages is more sensitive to the change of the cavitation number. With the increase of the cavitation number, the drag coefficient of the projectile with empennages increases sharply, and the empennages change the collapse morphology of the supercavity near the tail of the projectile. The cavity collapse at the tail of the projectile causes the drag coefficient fluctuations. The dimensionless length and diameter of the cavity formed by the projectile with empennages are greater than those formed by the projectile without empennages. When the cavity collapses at the tail of the projectile, the variation rates of the dimensionless length and diameter of the cavity for these two projectiles are different due to the influence of empennages.

Abstract:The plates are normally impacted by ogival-nosed projectiles on a one stage-gas gun to investigate the influence of material and configuration on the ballistic resistance of target. By changing the material and configuration of target, the ballistic limit and failure modes of the target under various impact conditions are analyzed. All the targets, including monolithic plates, double-layer plates with the same materials and double-layer plates with different materials, are of equal thickness. The velocity data and ballistic attitude image of projectile are acquired by high-speed camera, the residual velocity versus initial velocity curves and ballistic limit velocities of the projectiles are obtained based on experimental data. By analyzing the ballistic limit and surface density of target, the influence of layering order of target on its impact resistance is revealed from the impact efficiency. The experimental results indicate that the monolithic plates have a better ballistic performance than the double-layer plates with the same materials. The layering order affects the ballistic resistance of the double-plates with different materials, the configuration for anti-impact perfarmance is the upper layer of harder material and the lower layer of softer material, and also the layering order of plate on the ballistic resistance decreases with the increase of initial velocity of projectile. Moreover, it reveals that the ballistic resistance of aluminum alloy target is higher than that of steel target under the similar areal density.

Abstract:To more comprehensively and precisely reproduce mechanical behaviors of frictional and describe properties of energy dissipation, a kind of Iwan model considering variable normal load is developed. In the normal direction, a nonlinear spring is used to describe normal load variation and intermittent separation. In the tangential direction, the original Iwan model is used to describe micro-slip and macro-slip behavior. The relationship between tangential restoring force and relative displacement is derived and the transition criteria among motion states of the model is given. A simplified friction oscillator under harmonic excitation is analyzed to study the effect of different parameters of excitation on the system responses. The proposed model degrades into the original Iwan model when the normal load keeps constant, which validates the model well. This model considering coupling of micro-slip tangential force and variable normal force more comprehensively, exactly reproduces contact interface and effect on the system response. The separation of interface not only reduces damping capability of friction system and makes the responses high, but also strengthens nonlinearity of the system, so it should be avoided in the practical engineering.

Abstract:Floating vertical axis tidal current turbine (VATT) will occur pitching motion response in waves. To study the effect of pitching motion, a complex model of VATT moving in the waves is simplified to an impeller moving in the uniform current and superposed with harmonic motions, and the hydrodynamic performance of VATT is studied based on CFD viscous theory and ANSYS-CFX software, as well as the moving mesh and the sliding mesh. The CFX software is used to simulate the pitching motion under different speed ratio and rotating impeller is forced to pitch. The thrust coefficient and lateral force coefficient time history curves are also analyzed under different speed ratio by the method of least squares. The results show that, compared with turbine only rotating in uniform stream, the turbine under pitching motions has a little higher value in turbine's energy utilization. The instantaneous fluctuation amplitude of the thrust and lateral force under pitching motion are obviously higher than that of turbine under uniform stream, which is bad for the structural strength and fatigue effect of turbine in waves. The damping force is the main ingredient to turbine under pitching motion and the effect of added mass force is small.

Abstract:It is very important to assess failure mode of warship under explosion and shock loading. Stress triaxiality and Lode angle are all important factors to judge stress states of material. By combining the stress states of MMC failure criterion and strain, temperature of J-C failure criterion and taking stress states, strain and temperature into account, a dynamic failure criterion for ship-build metal was set up. A VUMAT material subroutine was introduced into ABAQUS and the ballistic perforation resistance of 2 mm ship-build mild steel was studied by simulation and experiments. The results showed that the new dynamic failure criterion based on stress triaxiality and Lode angle could predict the failure of ship-build metal under dynamic loading, which was more accurate than J-C criterion. The new criterion could be used to predict dimension of crevasse, failure mode and residual velocity under explosion, shock and penetration loading.

Abstract:To solve the problem that architects were always having problems in finding suitable architectural images effectively from websites, a semantic acquisition method of architectural images based on web annotation technology was proposed. First, the concepts and types of architectural images and semantics were defined. Second, the framework and operational processes of this method were illustrated. Finally, the feasibility and validity of this method were verified by famous building websites as examples. Regarding to operational process, there were three steps: building the architectural semantic dictionary by adding artificially and learning online; collecting 6 items of image-related texts (image's name, image's annotation, information around images, webpage's title, webpage's body, and the title of image's hyperlink) from websites where the images were founded; collecting semantics of images according to certain rules, relating them to image files and keeping them to the database of architectural images. This study indicates that the proposed method is feasible and easy to be operated. Architectural images can be automatically downloaded in batches and more than 30 items of architectural semantic characteristics will be collected, such as names, categories, themes of architectural images, as well as names and types of projects. As a result, the semantic acquisition method of architectural images will effectively overcome the problem that architectural images are hard to be searched and it will help architects to improve their abilities of innovation by using images from websites.

Abstract:To study the thermal environment characteristic of the riverside residential areas in severe cold region in winter, field measurements on air temperature and black-bulb temperature have been carried out in riverside residential area and inland residential area of Harbin on typical weather day, then quantitative methods are used to analyze the thermal environment differences in winter between riverside residential area and inland residential area, and the impact of building layout in residential area on thermal environment. Furthermore, human thermal sensation is evaluated according to the wind chill temperature. The results indicate that the thermal environment of riverside residential area is worse than that of inland residential area, and there are significant differences in thermal environment among varied building layout patterns. The mean air temperature of riverside residential area is 2.45 ℃ lower than that of inland residential area, the average black-bulb temperature of riverside residential area is 3.66 ℃ lower, the average wind velocity is 0.48 m/s bigger and the average wind chill temperature is 5.59 ℃ lower. The solar radiation has the maximum effect on raising riverside residential areas' temperature in winter, the second is buildings' layout. Row layout pattern has the highest cold degree, followed by the square, and the riverside entrance, enclosing and semi-enclosing layout pattern has the lowest cold degree. Besides, increasing the building interval in the row layout can effectively reduce the cold degree and improve the thermal comfort degree.

Abstract:The aim of this topic is to indicate the advantages of dynamic daylight performance metrics and advocate the acceptance of dynamic metrics in analysis of building daylight design cases. Firstly, this paper indicates that the dynamic metrics are more reasonable than statistic metrics (daylight factor) in evaluating the daylight environment via theoretical analysis. Then taking the weather data in Guangzhou as the calculation input, based on Daysim simulation results, the depth of daylight available area is defined by DA metric. Under the regional weather condition in Guangzhou, based on Daysim dynamic daylight simulation data, the daylight performance of 4 facade types is ranked via metrics DF/DA/UDI and compared with that ranked by daylight factor, and the result indicates the superiority of dynamic metrics in selecting the optimal design schemes. Furthermore, the daylight available area and probability of glare occurrence towards facades with various WWR and shading overhang size are analyzed, and the results can be adopted as design references which suggest that the dynamic metrics should be used to evaluate daylight performance and the areas where DA metric values are no less than DA_300 lx[50%] should be defined as daylight available area that could indicate the availability of side-lit windows well.

Abstract:Aiming at the mining brownfield of which the ecological environment is badly worsening, a mining brownfield park based on ecological tectonic is presented to keep ecological safety on brownfield landscape. The landscape ecological security patterns of mining brownfield park constructed by MCR model take the artificial natural ecological patches in brownfield parks as "origins" in ecological security pattern at landscape scale, which means the origin of artificial nature. The origins of artificial natural patches bind each other, and according to island theory model, the resistance contours between every origin forms saddle tangentially. This saddle area would become "strategic points" between different "origins" in ecological energy flow spreading process. By analyzing the selected landscape indexes and comparing with traditional planing design pattern, the ecological security pattern of mining brownfield park and the degree of landscaped fragmentation decline obviously, the landscape isolation diminishes obviously, while the landscape diversity reduces. The degree of landscape dominance and landscape spread increases.

Abstract:When treating waste water with low chemical oxygen demand to ammonium, the CANON process brings about a striking innovative effect. The denitrification performance of the CANON process was studied by adopting the aeration up-flow sludge bed reactor (AUSB). Under the condition of ammonia nitrogen being added as the one and only nitrogen source, the reactor shows 73% of the total nitrogen removal rate. With the gradual increase of inflow ammonia nitrogen and reduction of the hydraulic retention time, its denitrification ability continues to be promoted and the total nitrogen removal load reaches to more than 0.47 kg/(m³·d). By the 60th day since the study began, the visible particles appeared. During the start-up period, the activity of NOB in the system were suppressed effectively, and the value of Δρ(TN)/Δρ(NO₃^--N) was close to 8. After the operation of 135 d, the whole process of autotrophic denitrification of granular sludge was successfully started in a continuous flow reactor. The results demonstrated that increasing the influent load promoted the microbial growth, thus a more suitable growth conditions for CANON strain was built and NOB was gradually eliminated. By the interaction of a variety of biological populations, the reactor showed a high nitrogen removal efficiency, and the continuous flow of CANON process started successfully.