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1.
针对复杂海洋环境中声呐探测弱目标易被强干扰淹没的问题,提出一种对被动声呐探测到的强干扰源进行跟踪抑制的方法,通过对观测数据的互谱密度矩阵(Cross Spectral Density Matrix,CSDM)进行特征分解,根据干扰方位范围的先验知识,对干扰源的方位进行跟踪,依据方位信息选择代表强干扰的特征向量,依此根据不同的算法重构剔除了干扰信息的CSDM。数值仿真和海试数据验证结果表明,该方法能够在已知干扰初始方位区域的情况下自适应地抑制强干扰,较好地保留并提取目标信息,检测出感兴趣的目标。该方法为后续的目标识别与跟踪提供了有利条件。  相似文献   

2.
马敬广  徐晓男 《声学技术》2013,32(3):243-247
为了改善纯方位目标运动分析方法的性能,提出了一种水下目标方位预处理方法。该方法利用目标运动模型对观测方位序列进行预处理,经仿真验证,与常规的多项式拟合方法相比,能够有效降低水下目标方位观测量的估计误差,提高了目标运动分析的性能,可获得更高的运动参数估计精度。  相似文献   

3.
被动传感器系统的快速航迹起始算法   总被引:1,自引:0,他引:1  
针对传统航迹起始算法在纯方位目标跟踪应用中存在的问题,提出了一种基于被动式单传感器系统的快速航迹起始算法.算法通过分析二维纯方位目标运动的特点设定威胁目标的筛选规则,利用改进的启发式算法在最短时间内对威胁目标进行舷迹起始.再将基于逻辑的方法应用到纯方位坐标系下,进行一般目标的航迹起始.通过这两种方法在纯方位目标跟踪系统中的联合运用,不仅使目标航迹得到有效确认,而且为系统建立目标威胁等级提供了基础.仿真和实际系统的应用表明了此算法的有效性和实用性.  相似文献   

4.
罗美玲  马艳 《声学技术》2012,31(4):427-430
针对海洋环境中估计目标方位的误差而导致多传感器被动目标跟踪算法效果不佳、稳定性差的问题,提出一种稳健的多传感器被动目标跟踪方法。该方法首先将各个传感器的观测信息从角度转化为位置,从而有效地线性化了系统模型,然后运用卡尔曼滤波,在滤波过程中根据滤波预测值剔除通信过程中因误码率产生的失真角度测量值,并用预测值代替,从而有效地保证了目标跟踪方法的稳健性。最后进行了数值仿真,结果表明该方法在信息误差较大时也可以提供较为稳健的跟踪性能。  相似文献   

5.
应用图像处理中的Hough变换方法检测目标方位,并将方位跟踪转化为Hough域的点跟踪,用以解决两个目标或多个目标方位交叉问题。通过仿真数据验证这一方法稳定可行。  相似文献   

6.
针对单线阵进行弱目标跟踪时容易受到强目标影响的问题,将三元组线列阵进行分裂波束定向,可提高对弱目标的方位跟踪能力。通过将三元组线列阵等分为两个三元组子阵,对两个三元组子阵分别进行心形波束形成,利用各自心形波束输出进行分裂波束处理得到目标方位。与常规单线阵分裂波束目标跟踪方法相比,该方法不但能给出跟踪目标的左右舷信息,同时提高了不同舷侧存在多目标时的目标跟踪能力。对海试数据的实际处理结果表明,三元组线列阵分裂波束定向时提高了对多目标的方位跟踪能力。  相似文献   

7.
在已知固定目标方位的前提下 ,本文提出了—种根据固定目标回波的方位测量 ,建立状态方程和观测方程 ,利用稳态卡尔曼算法进行传感器方位偏差的配准方法。仿真实验结果表明这种方法是有效的  相似文献   

8.
针对纯方位被动目标跟踪中扩展卡尔曼滤波算法易发散的不足,提出了一种自适应的改进算法。该算法利用极大后验噪声估计器Sage-Husa对虚拟观测噪声进行实时在线估计,动态补偿线性化带来的误差。算法的对比仿真分析结果表明,AEKF较之EKF滤波效果有所改善,增强了稳定性,提高了精度,为ST纯方位被动目标跟踪的实现提供一种新的方法。  相似文献   

9.
庞玉红  严琪  陈托 《声学技术》2023,42(5):684-688
双曲调频信号的多普勒不变性可使运动目标匹配滤波输出的能量损失达到最小,在运动目标检测与参数估计中具有独特优势,已广泛应用于新型主动声呐。然而其多普勒不变性在提高检测能力的同时,会引入目标距离估计误差,从而影响主动声呐跟踪性能。文章在分析双曲调频信号距离估计误差的基础上,提出了目标跟踪算法的误差修正方法,通过将距离估计误差公式与传统观测方程及滤波算法进行融合,实现目标跟踪算法的误差补偿,显著提高了算法的跟踪性能,尤其是对快速运动目标的跟踪性能。  相似文献   

10.
石章松  王树宗  刘忠 《声学技术》2004,23(3):173-177
针对纯方位被动目标跟踪中,直角坐标系下的扩展卡尔曼滤波器容易发散,导致滤波精度很差的情况,文章中提出了一种直角坐标系下自适应卡尔曼滤波算法,对虚拟噪声进行了估计,动态补偿观测模型的线性化误差,削减系统的观测误差,并对其滤波理论及其算法进行了研究和仿真,结果表明,该算法提高了滤波的稳定性、快速性和精确性,优于一般的扩展卡尔曼滤波算法。  相似文献   

11.
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.  相似文献   

12.
13.
A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.  相似文献   

14.
On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……  相似文献   

15.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

16.
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill.  相似文献   

17.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

18.
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...  相似文献   

19.
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.  相似文献   

20.
Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.  相似文献   

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