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介绍了一种微波有源倍频器的设计方法。按照这种方法设计了一个X波段有源二倍频器,应用微波CAD软件进行了仿真与优化,并给出了仿真与实验的结果。实验结果表明,这种设计方法与过程在工程设计生产中是有效的。 相似文献
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CMMI模型和敏捷方法Scrum都是目前国际上主流的应用于软件开发过程的方法,文章分析了Scrum方法与CMMI相结合的可行性,提出了Scrum方法与CMMI相结合的软件配置管理过程。 相似文献
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针对模拟电路的软故障,文中提出了一种基于改进Elman神经网络与提高特征向量有效性相结合的诊断方法。该方法对不同情况下的输出信号进行3次小波分析,形成8维的特征向量,再与改进的Elman神经网络结合进行分类与诊断。将改进Elman神经网络应用于非线性模拟电路故障诊断中可提高其诊断率与分类率。文中对其诊断方法进行了实验对比测试,结果表明,该方法提高了诊断性能,其诊断率与分类率分别为92.5%和83%。 相似文献
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提出了一种基于深度学习的多视窗SSD (Single Shot multibox Detector)目标检测方法。首先阐述了经典SSD方法的模型与工作原理,并根据卷积感受野的概念和模型特征层与原始图像的映射关系,分析了各层级卷积感受野大小和特征层上默认框在原始图像上的映射区域尺寸,揭示了经典SSD方法在小目标检测上不足的原因。基于此,提出了一种多视窗SSD模型,阐述了其模型结构与工作原理,并通过106张小目标图像数据集测试,评估和对比了多视窗SSD方法与经典SSD方法在小目标检测上的物体检索能力与物体检测精度。结果表明:在置信度阈值为0.4的条件下,多视窗SSD方法的AF (Average F-measure)为0.729,mAP (mean Average Precision)为0.644,相比于经典SSD方法分别提高了0.169和0.131,验证了所提出算法的有效性。 相似文献
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Feature-guided shape-based image interpolation 总被引:1,自引:0,他引:1
A feature-guided image interpolation scheme is presented. It is an effective and improved, shape-based interpolation method used for interpolating image slices in medical applications. The proposed method integrates feature line-segments to guide the shape-based method for better shape interpolation. An automatic method for finding these line segments is given. The proposed feature-guided shape-based method can manage translation, rotation and scaling situations when the slices have similar shapes. It can also interpolate intermediate shapes when the successive slices do not have similar shapes. This method is experimentally evaluated using artificial and real two-dimensional and three-dimensional data. The proposed method generated satisfactory interpolated results in these experiments. We demonstrate the practicality, effectiveness and reproducibility of the proposed method for interpolating medical images. 相似文献
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为了解决医学图像在采集和传输过程中引入噪 声和干扰导致图像质量恶化从而严重影响医学诊断的问题,提出 一种基于剪切波(shearlet)域改进Gamma校正的图像增强方法。首先,通过剪切波变换,把 图像分解成高频 部分和低频部分;其次,用改进的Gamma校正处理剪切波分解后的低频部分以调整图像的整 体对比 度,采用改进的自适应阈值函数对高频部分进行去噪;最后,把剪切波反变换的重构图 像进行模糊对比 增强,以突出图像的细节信息。实验结果表明,本文算法的峰值信噪比(PSNR )、结构相似度(SSIM)和 绝对均值差(MAE)优于其他对比算法,尤其是PSNR的提升更加明显。这些 客观指标说明,本 文算法不仅能有效地抑制噪声,而且能明显改善增强对比度。从主观方面观察,本文算法与 其他算法相比,能获得更好的视觉效果。 相似文献
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通过傅里叶光学理论和透镜成像理论对轴棱锥线 聚焦与凸透镜点聚焦两种成像系统进行分析, 并探讨了它们对成像系统焦深的影响。利用ZEMAX光学设计软件,仿真模拟出系统在不同轴 向距离的截面 光强分布图。以蓝光LED为光源,对这两种成像系统进行实验验证,拍摄不同轴向距离处的 截面光强分布 图。结果表明,轴棱锥所具有的线聚焦特性,能将光线连续地会聚到沿轴线不同位置上,图 像的清晰度高, 且在最大无衍射距离内无需调焦,具有更大的焦深;理论分析、仿真模拟与实验结果相吻合 。 相似文献
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Mostafa Heydari Mohammad-Reza Karami Azizollah Babakhani 《Signal, Image and Video Processing》2016,10(7):1211-1218
Among different methods of image de-noising, partial differential equation (PDE)-based de-noising attracted much attention in the field of medical image processing. The benefit of PDE-based de-noising methods is the ability to smooth image in a nonlinear way, which effectively removes the noise as well as preserving edge through anisotropic diffusion (AD) controlled by the diffusive function. Today, AD filtering such as Perona and Malik (P–M) model is widely used for MR Image enhancement. However, the AD filter is non-optimal for MR images that have Rician noise. Originally, the PDE-based de-noising designed for additive Gaussian distributed noise was signal independent, but the Rician noise was signal dependent. In this paper, we proposed a new adaptive coupled diffusion PDE fitted with MRI Rician noise which not only preserved the edges and fine structures, but also performed efficient de-noising. Our method was an improved version of AADM (automatic parameter selection anisotropic diffusion for MR Images). For this purpose, we have presented a new adaptive method to estimate the standard deviation of noise. As the simulation results showed, our proposed diffusion effectively improved the improved signal-to-noise ratio (ISNR) and preserved edges more than P–M, AADM and unbiased NLM (UNLM—unbiased non-local means) methods to remove Rician noise in MR Images. 相似文献
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Uchino E. Suetake N. Koga T. Kubota R. Ichiyama S. Hashimoto G. Hiro T. Matsuzaki M. 《Electronics letters》2009,45(9):451-453
A novel plaque boundary extraction method for an intravascular ultrasound (IVUS) image employing image separability and Takagi-Sugeno's fuzzy inference model is presented. The membership functions are allocated heuristically with special consideration of the features of the IVUS image. The method has not only improved the accuracy of plaque boundary extraction but has also reduced the workload of medical doctors. 相似文献
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针对现有医学图像中存在有采集后图像质量不高、图像过暗等现象,对遗传算法中的选择、交叉、变异特性进行研究,同时结合粒子群优化、禁忌搜索及模糊增强算法,提出一种基于改进混合遗传的医学图像模糊增强方法.该方法通过对传统遗传算法改进,将粒子群优化思想及粒子空间对称分布原理引入以改善遗传算法缺乏明确的目标指向性、“突变”性过高的现象,并且为有效降低粒子的同一位置二次搜索,在算法执行过程中加入了禁忌搜索算法.最后,通过与模糊增强算法相结合,并设置二维方向寻优,可自适应的同时寻找到两个模糊参数Fp、Fe最优值,完成医学图像的模糊增强.实验结果表明,改进后算法可有效改善过暗医学CT图像的质量,增强效果较好. 相似文献
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分区域的医学图像高容量无损信息隐藏方法 总被引:1,自引:0,他引:1
针对医学图像的分区域典型特征,提出一种基于区域和直方图平移的高容量无损信息隐藏方法。本方法用最大类间距分割法求得原始图像的前景区域,再用聚合多边形逼近和图像拟合法得到其数据嵌入区域。在数据嵌入过程中,提出利用差值直方图循环平移和基于编码的直方图平移方法分别在前景和背景区域嵌入数据,提高了原始直方图平移方法容量和解决了溢出问题。实验结果表明该方法总的嵌入容量可达1 bit/packet以上,并且隐秘图像质量在40dB左右,适用于具有区域特征的质量敏感图像的大容量信息隐藏。 相似文献
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针对传统的医学图像分割算法存在组织边缘模糊、灰度不均匀和图像噪声高的问题,将信息熵和改进的粒子群算法相结合,提出了一种基于信息熵和改进的粒子群算法的医学图像分割方法,在确保信息熵最大的条件下,实现医学图像的最佳阈值分割.将信息熵最大化作为适应度函数,通过改进的粒子群算法优化获得最佳分割门限,实现医学图像的最佳阈值分割.选择不合噪声和含噪声的脑部图像为研究对象,通过直观分析、客观分析和分割速度分析发现,提出的新方法在很大程度上克服了传统医学图像分割算法存在的缺陷,分割速度和精度得到显著提升;与此同时,新的算法具有很强的鲁棒性和抗噪声能力. 相似文献
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Recent years have witnessed that the multimodal medical image fusion (MMIF) plays critical roles in clinical diagnostics and treatment. Many MMIF algorithms have been proposed to improve the MMIF images quality. The quality of multimodal medical fused images will significantly affect the results of the clinical diagnosis. However, little work has been designed to evaluate the effectiveness of MMIF algorithms and the quality of MMIF images. To this end, this paper presents a perceptual quality assessment method for MMIF. A MMIF image database (MMIFID) is first built to employ the classical MMIF algorithms, and the subjective experiment is conducted to assess the quality of each fused image. Then, a no-reference objective method is proposed for the perceptual quality evaluation of MMIF images,which uses Pulse Coupled Neural Network (PCNN) in Non-subsampled Contourlet Transform (NSCT). A fused image is decomposed by NSCT into low frequency sub-band (LFS) and high frequency sub-band (HFS). It is used to motivate the PCNN processing, and large firing times are employed to measure LFS and HFS. Finally, two components evaluation results are combined to obtain the overall objective quality score. Experimental results based on the MMIFID indicate that our presented method outperforms the existing image fusion quality evaluation metrics, and it provides a satisfactory correlation with subjective scores, which shows effectiveness in the quality assessment of medical fused images. 相似文献
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基于互信息方法的医学图像检索 总被引:4,自引:0,他引:4
提出了一种适用于医学图像检索的新方法,即最大互信息方法,使用该方法对超声图像库进行了检索实验,验证了基于最大互信息方法具有良好的检索性能;该方法既能满足位置不变性,旋转不变性和比例不变性,又能避免进行图像分割,从而避免了因图像分割引起的复杂计算,该方法还具有检索速度不受数据库中图像数目影响等优点,也适用于对一般图像进行相似性检索。 相似文献