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1.
A new kind of ultra wideband antenna, which consists of a leaf-like dipole and a dielectric block, is proposed and analyzed. The dielectric block is attached in parallel with the dipole near its feed point. Thus, the near field is attracted to the side where the dielectric block is located. It leads to a focusing effect of the energy in the far zone. The finitedifference time-domain (FDTD) method combined with the perfectly matched layers (PML) technique is used in the simulation of the antenna radiation characteristics. The research shows that, with proper dielectric loading and 50 Ωfeeding line, the bandwidth of the antenna can be up to 6.5 GHz, from 3.5 GHz to 10 GHz with VSWR (voltage standing wave ratio) less than 2.5.  相似文献   

2.
In order to study the movement of the long-distance torpedo-like autonomous underwater vehicle (AUV) which is controlled by the dynamic positioning system (DPS), by adopting momentum theorem and the angular momentum theorem, the appropriate movement math model for the long-distance torpedo-like AUV has been built and the thrust of DPS is distributed. Several representative movements of AUV are simulated, such as transferring between two random points and pointing circumrotation movement. The simulation result is analyzed. It shows that DPS including five thrusters can control the AUV movement steadily at low velocity.  相似文献   

3.
The kinetic parameters of the exothermic decomposition reaction of s-Tripicryaminotrinitrobenzene under linear temperature rise condition are studied by means of DSC. The results show that the empirical kinetic model function in differential form, apparent activation energy and pre-exponential constant of the reaction are 225.4 kJ·mol-1 and 1 019.53 s-1, respectively. The critical temperature of thermal explosion of the compound is 267.36 ℃.  相似文献   

4.
An algorithm of broadband minimum variance distortionless response (MVDR) based on the frequency energy normalization is proposed. First, every narrowband frequency component of the broadband signal is normalized by the total narrowband energy of all array elements, and the narrowband power is calculated by MVDR. Finally, final spatial energy spectrum can be obtained by averaging or summing all results of every narrowband frequency bin. Any prior-information about the noise or the signal is unnecessary for the proposed method in this paper. The processing gain of the proposed method compared to the conventional broadband MVDR can be obtained as long as the amplitude fluctuation of the array noise frequency spectrum is severer than that of the target signal. The validity of the method is validated by the optimal signal detection theory. Simulation and real data are used to validate the performance of the method. Analysis results show that about 4 dB processing gain compared to the general broadband MVDR can be reached by the proposed method.  相似文献   

5.
The relationship between the crystal lattice free volume,ΔV,and impact sensitivity,E_(dr),of ten nitramines has been analyzed. It was found that this relationship is not uniquely determined,i. e. it is not given only by their own ΔV values but fundamentally by the type and intensity of the intermolecular forces in the nitramine crystals. Also,relationships between the E_(dr)values,on the one hand,and bulk modulus,K,and shear modulus,G,on the other,have been the subject of discussion not only for pure cyclic nitramines but also for their PBXs,bonded by a poly-fluoro binder. The closest linear correlation exists between the E_(dr)values and dimensionless K·G~(-1) ratio which indicates the plasticity range. A similar relationship is valid also for the ΔV values. Relationships of the E_(dr) and / or ΔV values with the shear modulus or to the K·G~(-1) ratio reflect an unusual behavior of ε-HNIW to which the published morphological instability of this particular HNIW version might also be related.  相似文献   

6.
By using the ATV module of MSC. ADAMS, the dynamic simulation of recoil response of tank gun is analyzed.How the recoil force affects the bodywork and the suspension during gun firing, as well as the changing status of the gun muzzle‘s velocity are gained. All results and analyzing methods are offered for the designing basis of optimizing tank vehicle-gun match. The constructive exploration is beneficial to improving the general capability of tank.  相似文献   

7.
The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.  相似文献   

8.
In explosive research area, one of important trends is to study on the preparation technology of explosive microparticles. A new principle and method based on supercritical anti-solvent (SAS) process is put for ward and discussed for the preparation of explosive micro-particles. The satisfactory micro-particles of explosives can be obtained easily by its particular mechanism of creating micro-particles, and operating conditions at normal temperature. This method is good for further study and development.  相似文献   

9.
An expression for estimating the aeroheating on a warhead nose at different supersonic speeds is proposed by incorporating CFD (computational fluid dynamics) and the least-square method. Compared with the traditional estimation formula, the expression is more accurate, convenient and can be used in the optimized design of warheads. The error from the result obtained in the test of a ball cartridge flight is less than 3 %. It satisfies the engineering requirements.  相似文献   

10.
Stepped frequency radar waveform is put forward for improving the accuracy of radio fuze ranging. IFFT is adopted to synthesize one dimension high resolution range profile. Furthermore, the same range reject method and selection maximum method are made use of removing target redundancy and the simulation results are given. Characters of the two methods are analyzed, and under the proposal of Weibull distribution clutter envelope, the CFAR same range selection maximum method is adopted and realizes the accurate profile and ranging.  相似文献   

11.
The experimental study of the laser beam parameters of the pulse repetitive RF-excited diffusion cooled waveguide CO2 laser are presented. The measurements are carried out for the pumping pulse duration of 100 μs and pulse repetitive rates 5 - 14 kHz. The average power density delivered to the active medium is 76 W/cm^3. Three types of the pulses, namely the square, the sine and the triangular ones have been applied at the input as pumping pulses and their effects on the output power and the delay time have been studied. The output power of the radiation versus input power, pressure of the laser gas mixture and modulation frequency has been investigated. The results indicate that the output peak power for the three types of pulses increases with increase of the pressure of the laser gas mixture and with the input power where as it decreases with the repetition frequency. The delay time of the output pulse decreases with the increase of the repetition frequency and input power, where as it increases with the increase of the pressure of the laser gas mixture. The behavior of the output power and the delay time with duty cycle for square pulse has also been investigated.  相似文献   

12.
针对传统激光功率计无法实时检测的缺点,设计一种基于PIN光电二极管的小型激光脉冲能量和频率实时检测电路。在激光器输出窗口前端设置光学玻璃对激光输出进行透射和散射,利用PIN光电二极管探测激光散射信号并完成光电转换。微弱电信号经后续信号调理电路处理以外部中断方式触发单片机计时、计数,单片机同时采集调理电路的输出电压。系统最终实现了激光脉冲频率及能量的检测。测试结果表明:该系统的频率测量精度优于0.02%,能量测量精度优于1%,灵敏度优于0.8 V/mW,响应时间不大于3 ns。  相似文献   

13.
姚淑娜  苏宁  辛建国 《兵工学报》2006,27(6):1099-1102
对新型百瓦级射频激励扩散型冷却全金属矩形波导C02激光器进行了实验研究,实验中采用了CASE-I平行平面腔,试验结果表明,在采用10%透过率的输出镜时,激光输出最大功率达到146 W,电光转换效率达到17.3%.单位增益体积提取的激光功率达到9.46 W/cm3.  相似文献   

14.
脉冲激光引信微弱回波信号数字检测技术研究   总被引:5,自引:2,他引:5  
回波检测是脉冲激光引信工作的关键环节之一。其基本的数字检测方法是对微弱脉)中信号多点采样并求和后利用信号的相关性和噪声的非相关性来提高输出信噪比。在分析了多脉冲积累特点的基础上,研究了单脉冲积累方法,提出了复合积累方法。探讨了诸积累方法的优缺点,并进行了仿真,仿真结果与理论分析相吻合。最后给出了复合积累方法的原理框图和软件流程图。  相似文献   

15.
脉冲多普勒引信抗有源噪声干扰性能研究   总被引:2,自引:4,他引:2  
李泽  栗苹  郝新红  闫晓鹏  王建涛 《兵工学报》2015,36(6):1001-1008
为提高脉冲多普勒引信抗有源噪声干扰性能,定量研究有源噪声干扰对其作用机理,以处理增益为表征参量,基于功率谱定量研究了脉冲多普勒引信的抗有源噪声干扰性能。理论推导了在射频噪声、噪声调幅和噪声调频干扰作用下脉冲多普勒引信从接收回波至相关检测这一过程的输入、输出信干比和处理增益,获得了影响脉冲多普勒引信抗有源噪声干扰能力的信号特征参数,并进行了仿真验证。定量分析与仿真结果表明:脉冲多普勒引信具有较强的抗有源噪声干扰能力,抗有源噪声干扰能力主要决定于脉冲占空比与多普勒滤波器带宽。  相似文献   

16.
通过实验验证了脉冲激光辐照CCD引起的饱和干扰,详细分析了峰值功率、脉冲宽度、重复频率等脉冲激光参数,通过构建仿真模型分析了单个参数对探测器饱和阈值的影响,仿真结果表明:脉宽越大,峰值功率越高,重复频率越大,越能使探测器达到饱和状态。  相似文献   

17.
小波变换中的小波系是把基本小波进行伸缩和时移得到的,根据这一原理,提出一种快速估计单个脉冲载波频率的算法。该算法通过把基准单个脉冲进行伸缩和时移处理来构建一个函数系,然后求解该函数系中和被测单个脉冲相关性最大的函数,由该函数相对基准脉冲的尺度因子估计出被测单个脉冲的载波频率。文中对该算法进行了仿真验证。  相似文献   

18.
大气湍流和色散导致脉冲展宽的分析比较   总被引:1,自引:0,他引:1  
陆红强  赵卫  谢小平 《兵工学报》2011,32(4):432-438
分析对比了星地激光通信系统中由于大气湍流和大气色散导致的脉冲展宽.计算了大气湍流导致脉冲展宽量与湍流大气折射率结构常数、传输距离、传输链路天顶角和初始脉宽之间的关系.根据大气压强和温度随高度变化的实测数据,推导出1.55μm波段的大气折射率,计算得到大气色散导致脉冲展宽量与光谱宽度、传输距离、传输链路天顶角、初始脉宽和...  相似文献   

19.
脉冲压缩技术在无线电定高引信中的应用   总被引:1,自引:0,他引:1  
无线电定高引信作为一种重要的引信得到了广泛应用。作为一种以高度来控制引爆的引信,定高精度是其一个主要的指标。为得到较高的距离精度,目前使用窄脉冲作为发射信号,导致功率不高,作用距离有限。为了在获得高距离精度的同时提高引信的作用距离,必须采用脉冲压缩技术。本文对目前无线电定高引信的系统进行改进,在发射端采用线性调频方式发射宽脉冲信号,在接收端采用脉冲压缩技术对电路系统作分析推导,得到主要设计参数,并对信号进行仿真,得到了和理论分析相同的结果。  相似文献   

20.
基于增益可控运放的脉冲信号自动增益控制   总被引:1,自引:0,他引:1  
针对脉冲激光探测系统中存在的回波幅度变化大,阈值比较电路受脉冲前沿时差影响导致距离判别精度低的问题,提出基于脉冲信号峰值电压反馈的自动增益控制方法,利用峰值电压采样,反馈控制电压形成,压控增益调整来实现信号增益的可控。通过仿真和实验验证:证明该方法能够解决宽动态范围下脉冲信号增益自动控制问题,从而减小脉冲前沿检测时差,提高系统距离判别精度。  相似文献   

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