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101.
102.
基于直方图均衡化的Robinson图像边缘检测算法 总被引:1,自引:0,他引:1
针对图像边缘检测,现有Robinson相关算法存在效率低、阈值设定随机性大、易出现伪边缘等问题,提出一种改进Robinson的图像边缘检测算法。该算法利用直方图均衡化对图像进行增强,然后将Robinson算子原有的八方向梯度依照两两垂直原则组合为八组,分别计算每组梯度的范数,并取其最大值作为该像素点的梯度。最后取整幅图像的灰度均值作为阈值来识别图像的边缘像素和背景像素。实验表明,相对于现有相关算法,该算法检测结果更加清晰完整,同时避免了传统算子人为设定阈值随机性大的问题。 相似文献
103.
Image contrast enhancement using adjacent-blocks-based modification for local histogram equalization
Infrared images usually have some non-ideal characteristics such as weak target-to-background contrast and strong noise. Because of these characteristics, it is necessary to apply the contrast enhancement algorithm to improve the visual quality of infrared images. Histogram equalization (HE) algorithm is a widely used contrast enhancement algorithm due to its effectiveness and simple implementation. But a drawback of HE algorithm is that the local contrast of an image cannot be equally enhanced. Local histogram equalization algorithms are proved to be the effective techniques for local image contrast enhancement. However, over-enhancement of noise and artifacts can be easily found in the local histogram equalization enhanced images. In this paper, a new contrast enhancement technique based on local histogram equalization algorithm is proposed to overcome the drawbacks mentioned above. The input images are segmented into three kinds of overlapped sub-blocks using the gradients of them. To overcome the over-enhancement effect, the histograms of these sub-blocks are then modified by adjacent sub-blocks. We pay more attention to improve the contrast of detail information while the brightness of the flat region in these sub-blocks is well preserved. It will be shown that the proposed algorithm outperforms other related algorithms by enhancing the local contrast without introducing over-enhancement effects and additional noise. 相似文献
104.
水声信道的严重双扩特性极大地限制了水声高速通信的稳健性。针对近程高速水声通信技术的需求,该文基于水声毫米波频段,提出了一种基于超奈奎斯特发射技术及高阶调制技术的单载波的水声毫米波通信技术。而超奈奎斯特发射技术以及高阶调制给接收机带来了极大的挑战:一是超奈奎斯特发射技术引入了严重的符号间干扰,二是高阶调制系统的符号检测对信道估计的精度要求很高。针对以上问题,该文提出了一种基于迭代信道估计技术的迭代软反馈DFE接收机技术。仿真实验表明:采用128QAM高阶调制时,在较为严重的多途衰落信道条件下,采用所提出的接收机可以在15 dB时实现无误码传输。信道水池试验证明:当通信带宽为300 kHz,通信符号率为300k符号/秒且采用64QAM调制时,在发射平台慢速运动的条件下可以实现900 kbps的净数据率,其相应的频谱利用率高达6 Bits/s/Hz。 相似文献
105.
We have investigated the role of the metal/oxide junction interface on the resistive switching (RS) characteristics in WO3+x films. The WOx films are fabricated on Pt substrates by magnetron sputtering at room temperature. Top metal contact (Au or Al) is fabricated by using thermal evaporator. The thicknesses of WOx films and top electrodes are 1 μm and 200 nm, respectively. It has been found that the bi-polar RS direction is dependent on the choice of top metal electrode, Au or Al. The sample with a Au top electrode shows clockwise (CW) RS mode whilst the sample with a Al top electrode shows counter-clockwise (CCW) RS mode. The on/off ratio is 10 times for Au/WOx/Pt and 100 times for Al/WOx/Pt. The bi-polar RS modes are modeled in terms of the difference in the electronegativity of the top and bottom electrodes. 相似文献
106.
针对目前分数间隔盲均衡算法存在的缺陷,提出了基于分数间隔的四二阶归一化累积量盲均衡算法.先对接收信号进行分数间隔采样,然后利用四二阶归一化累积量将盲均衡算法归结为无约束的极值问题,从而简化了算法,加快了收敛速度,降低了误码率.仿真验证了算法的有效性. 相似文献
107.
108.
A kinetic study of the reaction of hydroxide ion with (CO)5MoC(XCH2CH2OH)(C6H5) (X = O for Mo-OR, and X = S for Mo-SR), and (CO)5WC(OCH2CH2OH)(C6H4-Z) (W-OR(Z)) is reported. The results are consistent with a pathway in basic solution that involves rapid deprotonation of the OH group followed by rate-limiting cyclization. The parameter k1KOH for the reaction of W-OR(Z) was determined as a function of the phenyl substituents. They were found to correlate well with the Hammett equation. The dependence of the reactivity on the metal atoms in the complexes M-OR (M = Cr, Mo and W) shows that the reactivity decreases slightly down the group of the Periodic Table, while for M-SR the reactivity increases slightly down the group. A plausible explanation of these results is offered based on electronegativity values of the metal atoms. The much higher ρ(k1KOH) value for W-OR(Z) over W-SR(Z) arises mainly due to the stabilization of the reactant carbene complex by the stronger π-donor effect of oxygen over sulfur. 相似文献
109.
110.
By using a coarse-grain representation of the molecular electronic density, we demonstrate that the value of the condensed
Fukui function at an atomic site is directly related to the polarization charge (Coulomb hole) induced by a test electron
removed (or added) from (at) the atom. The link between the formation of an electron-hole pair and the condensed Fukui function
provides insights on the possible negativity of the Fukui function which is interpreted in terms of two phenomena: overscreening
and over-strengthening. 相似文献