基于复杂海空背景行均值曲线的海天线定位算法

复杂海空背景下红外舰船目标总是出现在海天线附近,因此获取海天线位置能确定目标的潜在区域。利用海天线区域在背景灰度上的渐变特性,提出了一种海天线定位方法,该方法首先运用形态学开运算抑制高频目标和杂波、提取平滑背景;然后采用背景行均值曲线首次突降区间检测算法,定位出一个窄的海天线区域,其中线即为工程误差范围内的近似海天线。实验结果表明,该海天线定位算法准确率高、适应于复杂海天环境。

行均值梯度与直线拟合联合优化的UUV海面红外图像海天线检测

在近海面水下无人航行器(underwater unmanned vehicle,UUV)的红外图像采集过程中,由于波浪起伏引起的高倾斜度、海空背景复杂等原因,红外图像的噪声过大,不利于目标的识别与海天线的检测。为此提出了一种海天线检测的改进方法。首先,将经过中值滤波和非线性增强预处理后的红外图像进行处理,得到行均值梯度图,确定海天线粗略位置;然后对其中的天空区域和海面区域进行滤波平滑处理,平滑二者背景中灰度起伏较大的噪声;最后利用优化的直线拟合法对天空区域和海面区域滤波后的图像进行海天线提取。实验结果表明,该方法可改善海天线位置的检测效果,具有较强的通用性,适用于复杂的海天环境。

海天复杂背景下红外目标的检测跟踪算法

在分析海天复杂背景下红外目标图像特征的基础上,提出适合该环境的红外目标检测算法.该算法采用行均值相减的方法抑制海平面非线性温度场的影响,并进行中值滤波处理.对于更加复杂的环境,选用数学形态滤波法抑制背景中的大面积云团或海浪,从而确定出目标区域来进行目标图像的分割及增强.同时,综合使用图像捕获区域指定、运动目标检测法、弱目标的增强提取、记忆外推功能、数据融合加权跟踪方法,来保证在海天复杂背景下红外目标的可靠跟踪.实验表明,该算法能较好地处理海天复杂背景下红外目标的检测,且算法易于硬件实现,提高目标检测的实时效率.

基于模态柔度差曲率的梁结构损伤识别

对于梁式结构的损伤识别,模态柔度比结构的频率和位移模态更加灵敏,通过结构的前几阶模态就可以容易计算得到。文中提出了基于柔度差曲率的损伤识别方法,通过3种方式计算所提指标,将得到的指标进行损伤敏感性对比,在简支梁设置一处、多处和支座处的损伤工况,在两跨连续梁设置多个和支座处的损伤,仿真结果表明,通过模态柔度行均值计算的柔度差曲率最好,柔度列最大元素计算的指标次之,柔度对角元素计算的指标可以进行简支梁1处损伤,但对多处损伤有些模糊。

C-means-based ant colony algorithm for TSP

To solve the traveling salesman problem with the characteristics of clustering,a novel hybrid algorithm,the ant colony algorithm combined with the C-means algorithm,is presented.In order to improve the speed of convergence,the traveling salesman problem(TSP)data is specially clustered by the C-means algorithm,then,the result is processed by the ant colony algorithm to solve the problem.The proposed algorithm treats the C-means algorithm as a new search operator and adopts a kind of local searching strategy—2-opt,so as to improve the searching performance.Given the cluster number,the algorithm can obtain the preferable solving result.Compared with the three other algorithms—the ant colony algorithm,the genetic algorithm and the simulated annealing algorithm,the proposed algorithm can make the results converge to the global optimum faster and it has higher accuracy.The algorithm can also be extended to solve other correlative clustering combination optimization problems.Experimental results indicate the validity of the proposed algorithm.

Numerical analysis of behavior of active layer in rotary kilns by discrete element method

The behavior of the active layer of material bed within rotary kilns plays a key role in industrial applications.To obtain its influences on industrial process,different regimes of particle motion have been simulated by discrete element method(DEM) in three dimensions under variant rotation speeds,filling degree,based on the background of induration process of iron ore pellets.The influences of the mentioned factors on the maximum thickness of the active layer and the average velocity of particles have been investigated.The average velocity of particles increases with Froude number following the power function over a wide range,and the maximum thickness rises with increasing rotation speed in a way of logarithm.The influence of the filling degree f on the maximum thickness exhibits a good linearity under two classic regimes,but the increasing of the average velocity of the active layer is limited at f=0.4.This basic research highlights the impact of the active layer within rotary kilns,and lays a good foundation for the further investigation in mixing and heat transfer within the particle bed inside rotary kilns.

The effect of actuation frequency on the plasma synthetic jet

The flow induced by plasma synthetic jet actuator was simulated through solving the Reynolds-averaged Navier-Stokes equations augmented by body force phenomenological plasma model.The effect of actuation frequency on the plasma synthetic jet was examined by case study.The numerical results present that with the actuation frequency increasing,the stream-wise distance of the adjacent vortex pairs induced by the actuator decreases monotonically,which is the same as the situation of the velocity fluctuations field caused by the vortex pairs.When the actuation frequency is 60 Hz,the vortex pairs formed during the adjacent actuation periods merge together quickly,and the flow structure in the downstream region is more close to that of the steady case.The actuation frequency has no visible influence on the time-averaged flow field of plasma synthetic jet.However,when the actuation frequency is relatively low(f<40 Hz),the momentum flux close to the actuator increases with the actuation frequency increasing,which is contrary to the situation in the far field from the wall.

WEAK TRAVELLING WAVE FRONT SOLUTIONS OF GENERALIZED DIFFUSION EQUATIONS WITH REACTION

The author demonstrate that the two-point boundary value problemhas a solution (A,P(8)), where III is the smallest parameter, under the minimal stringent resstrictions oil f(8), by applying the shooting and regularisation methods. In a classic paper)Kolmogorov et. al. studied in 1937 a problem which can be converted into a special case of theabove problem.The author also use the solutioll (A, p(8)) to construct a weak travelling wave front solutionu(x, t) = y((), (= x -- Ct, C = AN/(N + 1), of the generalized diffusion equation with reactionO { 1 O.IN￣1 OUI onde L k(u) i ox: &) ￣ & = g(u),where N > 0, k(8) > 0 a.e. on [0, 1], and f(s):= ac i: g(t)kl/N(t)dt is absolutely continuouson [0, 11, while y(() is increasing and absolutely continuous on (--co, +co) and(k(y(())ly,(OI'), = g(y(()) -- Cy'(f) a.e. on (--co, +co),y(￣oo) ￣ 0, y(+oo) ￣ 1.