为研究基于混合气体燃料的旋转爆震发动机燃烧室内流场特性,对混合气体燃料(H2+C2 H4+C2 H2)与空气在燃烧室内掺混的冷态流场进行了三维数值仿真研究.根据数值仿真结果,系统地描述了燃烧室内混合气体的流动特性,对比分析了不同喷注结构(燃料喷注深度、空气喷注环缝宽度)及不同的气体质量流率等因素对三维冷态流场及掺混的影响,并用掺混不均匀度定量评价了混合气体燃料与空气掺混的程度.研究结果表明,在文中给定的计算参数条件下,随着空气环缝宽度的增大,掺混效果能够得到一定提升;随着燃料喷注深度的增大,掺混效果有所下降;随着空气及燃料的质量流率的增大,燃烧室头部掺混效果略有下降,在中部掺混效果得到提升.

A control strategy without current and rotor-position sensors is proposed to drive the ultra-high-speed permanent magnet synchronous motor (UHSPMSM) fed by current source inverter (CSI), which is beneficial to the simplification of control structure as well as the reduction of system size and cost. In the proposed control strategy, command currents of the CSI are obtained by mathematical calculation with reference currents of the motor stator, leading to the removal of current sensors. In addition, an improved sliding- mode-observer (SMO) is used to calculate rotor position, allowing the rotor position sensor to be eliminated. A prototype and the control system were built and the control strategy simulation by utilizing the actual parameters of the prototype was conducted, which verify the effectiveness of the proposed control strategy under 550000rpm.

The Minimum Connected Dominating Set (MCDS) problem is a fundamental problem in wireless ad hoc networks. The majority of approximation algorithms for this NP-hard problem follow a two-phased approach: The first phase is to construct a Maximal Independent Set (MIS), and the second phase is to connect the nodes in it. The upper bounds of the MISs play a key role in the design of constant approximation MCDS algorithms. This paper considers this problem for 3D heterogeneous ad hoc networks, where the transmission ranges of nodes are allowed to be different. We prove upper bounds of MISs with two classical mathematical problems, the Spherical Code Problem and the Sphere Packing Problem. When the transmission range ratio (the ratio of the maximum transmission range over the minimum transmission range) is (1, 1.023], (1.023, 1.055], (1.055, 1.082], ..., we reduce the MIS upper bounds from the best-known results 22 | O P T | + 1 , 23 | O P T | + 1 , 24 | O P T | + 1 , ..., to 12 | O P T | + 1 , 13 | O P T | + 1 , 14 | O P T | + 1 , ..., where OPT is an optimal CDS and | OPT | is the size of OPT . With the bounds of MISs, the approximation ratio of MCDS algorithms can be reduced from 25.02 to 16.02 in heterogeneous 3D wireless ad hoc networks.

为研究大口径火箭增程榴弹发动机点火时刻以及助推时间对射程的影响,建立了火箭增程榴弹的质点外弹道模型,利用Matlab解算了火箭增程榴弹外弹道质心运动微分方程组.以某155 mm榴弹为算例,研究了榴弹在发动机不同点火时刻以及助推时间下的增程效果.研究结果表明:火箭发动机的点火时刻对射程影响较大,可以改变约30％的射程;助推时间对射程影响不超过5％;通过增程方案的合理选择可以实现单门炮多发弹同时弹着.

编队控制模型仿真是无人机编队设计中不可或缺的一部分.但当无人机规模较大时,仿真耗时问题突出.为解决仿真耗时问题,文中讨论了一种基于GPU的并行仿真方法并对所涉及的CUDA程序进行了优化.该方法设法将控制模型拆分成多个子模型,然后在多个仿真机上利用GPU同时求解子模型以提高效率.仿真结果验证了方法的正确性和高效性,同时也验证了GPU在大规模矩阵运算中的优势,且随着规模增大,优势愈加突出.

In order to further study on geomagnetic navigation technology,the paper introduced the the basic principle of geomagnetic navigation,analyzed the research progress home and abroad,including the building of geomagnetic navigation system,error compensation technique of geomagnetic sensors,and summarized the technical keys of the posture calculation al-gorithms,the geomagnetic models,the applications of geomagnetic maps and the geomagnetism-based integrated navigation technology,then discussed the existing problems in research of geomagnetic navigation.Finally,the developing tendency and the application prospects of geomagnetic navigation were expected.

Tri-benzene organic emission is a kind of toxic exhaust commonly produced in petrochemical industry.There are some characteristics,such as large emissions,low concentration,difficult centralized processing and decontamination.So,we set up a device to generate a large volume and stable microwave plasma at atmospheric pressure.The working gas could be nitrogen,oxygen or air with the gas flow rate of 0.3～10 L/min to generate the plasma.By experiments,we studied the effect of microwave propagation on the plasma characteristics under different working gas.Then p-Xylene exhaust gas was treated with three kinds of plasma.The results show that removal efficiency of p-Xylene is higher than 95％ in different microwave power and gas flow rate,and the lowest treatment microwave power can be achieved by 1 000 W with a great performance.In the air plasma treatment condition,the p-Xylene concentration can be up to 2 400 mg/m3 with little incomplete oxidized production.However,the nitrogen oxides are generated as by-products during the reaction,which have to be passed to the alkali solution to be removed.The results show that atmospheric microwave plasma can efficiently and completely reduce the p-Xylene content of exhausts,and other similar organic compounds in the exhaust gas also have apparent removal efficiency.The method has great potential environmental protection industry.

A two-side optimization problem where the intercepting satellite pursued the target satellite was studied in this paper.In the pursuit-evasion game,it was assumed that both sides use the continuous thruster and suffer from the earth central gravity with J2 perturbation.The dynamics equations were established to describe their three dimensional motion.Then the optimal control outputs of both side satellites were obtained by building the systems Hamilton and applying the functional extremal condition.The pursuit evasion games was transformed to the two point boundary value problem.At last the new problem was solved with the mixed numerical method where an initial solution was acquired by the genetic algorithm and sent to nonlinear programming as its starting value.Simulation was used to obtain the optimal interception and escaping trajectories of the two satellites and validate the proposed method.

针对拦截卫星和目标航天器都可以采用幅值受限连续推力进行轨道机动时的卫星末端拦截控制问题,由于对抗双方都会采用对自己有利的控制策略来实现追击和逃逸,因此将该问题可以看作追踪逃逸问题.由于两卫星距离较近,因此将非线性拦截逃逸相对动力学简化为CW方程.根据拦截任务终止要求引入零控脱靶矢量将动力学方程降阶,采用拦截脱靶量和燃料消耗作为二次最优目标函数,推导了卫星轨道次优控制策略,仿真表明该控制方法可以在目标卫星具有机动逃逸能力时仍能成功将其拦截.

In this paper, the fatigue life of a mechanical elastic wheel is studied to improve its reliability and dura?bility . The finite element model of the fatigue tests is established by combining the structure and the loading mode of a mechanical elastic wheel. Sine and cosine loads with the same amplitude and frequency are applied to simulate a load cycle process of the wheel skeleton. The fatigue life is predicted on the basis of Miner linear fatigue cumulative damage theory. The analysis results show that the fatigue failures of the wheel skeleton is mainly centered on the connection of the flexible ring composite clip and hinge group. The minimum fatigue life is 4.03 × 105 times. The fatigue life nonlinearly increases as the number and cross-section area of the hinge group increase. The fatigue life decreases as the actual load increases.

According to the characteristics of the compound coaxial helicopter, the general aerodynamic forces and moments of rotors, wing, fuselage, stabilator, vertical stabilizers (containing the rudder) and propeller were modeled and a trimming equation set was established accordingly. In view of the controlling redundancy problem, a control strategy was studied for the compound coaxial helicopter under conversion mode, using the linear transition method and minimal power optimization transition method. A sample compound coaxial helicopter was taken as an example to demonstrate the effectiveness of the method. Then the trimming values, the attitude angles and the power of these two methods were compared. The result shows that both the two methods can solve the controlling redundancy problem, while the trimming values and the attitude angles are reasonable and the linear transition method is better in the smooth change of the control values, the difficulty level of the controlling system and the flight quality.

Small unmanned aircraft has been the subject of extensive research because of its wide use in civil and military fields. In this paper, we have set up a global visual navigation platform and completed the autonomous flight control of the aircraft. On measurement aspect, locations and attitude angle are obtained by image processing algorithm. The paper describes an adaptive image segmentation algorithm based on color space, which can make accurate detection in different light conditions. Camera correction algorithm is applied to provide locations with higher precision, and the feedback rate of image program meets system requirements well. On control aspect, digital control of the system is decoupled into four channels. We adopt an incremental PID controller for each channel and achieve good response effects respectively. The aircraft performs well in hovering and autonomous flying according to planed path, which demonstrates the stability and accuracy of the system.

In this paper, a nonlinear controller is designed and implemented for longitudinal–lateral motion of a model-scaled helicopter. The underlying principle of controller design is the backstepping technique with slight modifications to accommodate the helicopter model. It is proved theoretically that, under the proposed controller, velocities and yaw angle of the closed-loop system are capable of tracking reference signals. A practical helicopter testbed is constructed to test the performances of the closed-loop system. Experimental results of practical flight tests demonstrate that performances of the closed-loop system are satisfactory.

The fault-tolerant topology is important for multi-agent systems to complete the established objectives and tasks based on distributed cooperative control. The fault-tolerant topology of multi-agent systems is studied. A clustering algorithm based on weight is presented, and the hierarchical topology is constructed by distributed extraction of the virtual backbone network. A bi-connected network is realized using a distributed algorithm which combines articulation node-based algorithm with control of relay nodes on the basis of hierarchical structure. Application of the method to the networked fire-control system is represented. Experimental results show that the proposed methods enhance the fault tolerance of topology for multi-agent systems, which lays the foundations for the networked unmanned warfare theory into practice.

以Fokker 27机群的过载-超越数曲线族为基础,建立了严重谱对应的严重超越数包线的获取方法.首先对外场使用的Fokker 27飞机机群的过载-超越数曲线进行筛选,得到59架飞机的过载-超越数曲线,采用线性累积损伤理论计算得到59架飞机每次飞行的损伤；假定机群载荷损伤服从对数正态分布,以严重谱下安全寿命满足机群寿命可靠度要求为准则,给出了严重谱的损伤程度.其次,采用对数正态分布描述指定过载下超越数的分布特性,外推得到满足损伤要求的严重超越数包线及对应的概率要求.结果表明,Fokker 27飞机严重过载-超越数曲线包线对应的超越数增量为1.117倍标准差.

This paper present the design and implementation of a dual-redundant flight control system for a miniature autonomous helicopter, named SRD-Heli. The systematic design procedure includes hardware integration, flight control law, exchange scheme, as well as experimental evaluation. A dual-redundant control architecture is adopted to construct the flight control system for the helicopter. The control architecture is composed by (1) an active flight control law designed for the active computer, which works in normal condition, (2) a standby flight control law to effectively control the helicopter by standby computer in fault condition. The result of actual flight tests shows that the flight control system is capable of achieving the desired performance.

According to the characteristics of the compound coaxial helicopter, general aerodynamic forces and moments of rotors, wing, fuselage, horizontal stabilizer (contains the elevator), vertical stabilizers (contains the rudder) and auxiliary propeller are modeled. A control strategy and its corresponding trimming algorithm are studied for the compound coaxial helicopter under various steady-state flight conditions. The conditions include the hover and low speed flight in helicopter mode, high speed flight in airplane mode, especially the conversion mode from helicopter to airplane with the linear transition method. Together with the control strategy, the trimming method is investigated to obtain the trimming values. A small-scale compound coaxial helicopter is taken as an example to demonstrate the effectiveness of the method. The result shows that the trimming values, the lift distribution of rotors and the wing under the whole steady-state flight conditions are reasonable.

The initial rotor position of brushless DC motor (BLDCM) is very important, not only for the anti-reverse rotation startup but also for the maximum starting torque. This paper analyzed the relation between the changing trends of the floating phase terminal voltages and the initial rotor position when voltage vectors were applied to the stator windings. A novel method was presented to estimate the initial rotor position based on the stator core saturation. In the proposed method, three voltage vectors were applied to the stator windings, and then, the changing trend of each floating phase terminal voltage was detected one by one. As a result, the 60 degree resolution could be achieved. This method can be implemented conveniently without current sensors, and is suited for sensorless BLDCM applications, in which low cost is the major consideration. The proposed method was validated by the results on the BLDCM experiment platform, which was controlled by the STM8S903K3 microprocessor. © 2012 Chin. Soc. for Elec. Eng.

A robust automatic flight control system is designed for a small scale unmanned helicopter in this paper.We first apply system identification to the design of a high-bandwidth controller for robotic helicopters.The overall concept is to extract a complete set of non-parametric input-to-output frequency responses that fully characterize the coupled helicopter dynamics,and then apply a nonlinear search algorithm for a linear high-fidelity simulation model that matches the frequency response data set.The H∞ loop-shaping method is used to design the inner loop of the unmanned helicopter based on the identified model.The greatest common right divisors(GCRD) method is employed to move the transfer function matrix from the real system to the target system,which is a very useful way to solve the difficulties in choosing a proper weighting matrix in H∞ loop-shaping.Compared with the traditional method,the system using the new method exhibits a larger robust stability margin,and the decoupling and the bandwidth of the system are also improved considerably.Furthermore,it reduces the complexity and blindness for the designer to find the proper weighting matrix.The simulation results prove that the unmanned helicopter system achieves a top level control performance that conforms relevant requirements in military standards ADS-33E.

A novel adaptive path following controller was presented for a miniature autonomous helicopter with uncertain inertial parameters and external disturbance.It was implemented by using dual-loop structure,including an outer-loop for path following and an inner-loop for attitude control.The outer-loop controlled the attitude angles and lift forces to track the expected path and velocity,and the inner-loop was designed as a attitude controller based on L1 adaptive controller.The uncertain inertial parameters were and external disturbance were also compensated online by using parameter adaptive update laws in the inner-loop.The stability analysis for the inner-and outer-loop was provided separately and the closed-loop stability analysis was given on the basis of time-scale separation assumption.Finally,a simulation and a flight test were carried out.The results demonstrate that the feasibility and performance of the proposed controller.