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71.
介绍Verilog-A设计语言的特点,基于Sigma Delta系统介绍分级设计思想.分析开关电容型Sigma Delta调制器的非理想特性,主要包括时钟抖动、开关热噪声、运放增益、摆率等.在建立各自噪声模型的基础上,基于Verilog-A对二阶Sigma Delta系统行为级完整建模,通过仿真结果的比对,验证Verilog-A建模,总结其可准确预测指标并在一定程度上有效地削减仿真时间的优点. 相似文献
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73.
船舶蒸汽动力装置自动控制的首要任务是机组的负荷控制。传统的PID控制算法由于具有结构简单、易于实现、可消除静差等优点得到了广泛的应用,但它受控制对象的影响较大,只有在各参数整定良好的前提下才能得到满意的控制效果。根据上述情况,结合船舶蒸汽动力单元工况变化频繁的特点,提出一种基于输出响应的自适应PID算法,以提高控制系统适应负荷变化的能力。方法在保留传统定值PID控制算法优点的同时,引入模糊控制在线整定PID控制参数,改善了机组的负荷控制特性,具有一定的工程应用价值. 相似文献
74.
基于Haar小波变换高频特征的图像质量评价算法 总被引:1,自引:0,他引:1
在分析人类视觉系统(HVS)特性的基础上,提出一种基于Haar小波变换高频特征的图像质量评价算法(CSSIM)。此方法首先将图像进行小波变换得到不同方向和不同频率的4个频带划分,在3个高频频带比较边缘结构信息上根据人类视觉系统特性,赋予3个频带比较结果相应视觉权重值,最终得到归一化的图像质量评价指标CSSIM。通过非线性回归拟合分析,证明了提出的算法(CSSIM)相对图像结构相似度评价算法(MSSIM)及其改进算法(MGSSIM)更符合人类的主观视觉感受。 相似文献
75.
一种改进的应用于噪声数据中的KNN算法 总被引:1,自引:0,他引:1
基于实例的KNN算法不可避免地要依赖于数据的质量,但原始数据含有噪声,因而KNN算法的结果势必会因为数据中的噪声而受到严重的影响。事实上,大多噪声都服从一定的模型,而且模型一般是已知的。充分利用数据中的噪声模型,以减小噪声对KNN算法结果的影响。通过实验结果表明该方法是有效的。 相似文献
76.
77.
Shapiro DB Maestre MF McClain WM Hull PG Shi Y Quinby-Hunt MS Hearst JE Hunt AJ 《Applied optics》1994,33(24):5733-5744
The coupled-dipole approximation has been used to model polarized light-scattering data obtained from the sperm of the octopus Eledone cirrhosa. Mueller scattering-matrix elements (which describe how a sample alters the intensity and degree of polarization of scattered light) were measured as a function of angle. The sample was modeled as a helical fiber believed to correspond to a DNA protein complex. It was necessary to propose an inherent anisotropy in the polarizability of the fiber in order to fit the data. The direction of the principle axes of the polarizability were determined by comparing the model with experimental data. The results suggest that the 2-nm DNA fibers are perpendicular to the thick fiber that defines the helical geometry of the octopus sperm head. 相似文献
78.
3D Motion recovery via affine Epipolar geometry 总被引:10,自引:6,他引:4
Larry S. Shapiro Andrew Zisserman Michael Brady 《International Journal of Computer Vision》1995,16(2):147-182
Algorithms to perform point-based motion estimation under orthographic and scaled orthographic projection abound in the literature. A key limitation of many existing algorithms is that they operate on the minimum amount of data required, often requiring the selection of a suitable minimal set from the available data to serve as a local coordinate frame. Such approaches are extremely sensitive to errors and noise in the minimal set, and forfeit the advantages of using the full data set. Furthermore, attention is seldom paid to the statistical performance of the algorithms.We present a new framework that allowsall available features to be used in the motion computations, without the need to select a frame explicitly. This theory is derived in the context of theaffine camera, which preserves parallelism and generalises the orthographic, scaled orthographic and para-perspective models. We define the affine epipolar geometry for two such cameras, giving the fundamental matrix in this case. The noise resistant computation of the epipolar geometry is discussed, and a statistical noise model constructed so that confidence in the results can be assessed.The rigid motion parameters are then determineddirectly from the epipolar geometry, using the novel rotation representation of Koenderink and van Doorn (1991). The two-view partial motion solution comprises the scale factor between views, the projection of the 3D axis of rotation and the cyclotorsion angle, while the addition of a third view allows the true 3D rotation axis to be computed (up to a Necker reversal). The computed uncertainties in these parameters permit optimal estimates to be obtained over time by means of a linear Kalman filter. Our theory extends work by Huang and Lee (1989), Harris (1990), and Koenderink and van Doorn (1991), and results are given on both simulated and real data. 相似文献
79.
Although few-shot learning (FSL) has achieved great progress, it is still an enormous challenge especially when the source and target set are from different domains, which is also known as cross-domain few-shot learning (CD-FSL). Utilizing more source domain data is an effective way to improve the performance of CD-FSL. However, knowledge from different source domains may entangle and confuse with each other, which hurts the performance on the target domain. Therefore, we propose team-knowledge distillation networks (TKD-Net) to tackle this problem, which explores a strategy to help the cooperation of multiple teachers. Specifically, we distill knowledge from the cooperation of teacher networks to a single student network in a meta-learning framework. It incorporates task-oriented knowledge distillation and multiple cooperation among teachers to train an efficient student with better generalization ability on unseen tasks. Moreover, our TKD-Net employs both response-based knowledge and relation-based knowledge to transfer more comprehensive and effective knowledge. Extensive experimental results on four fine-grained datasets have demonstrated the effectiveness and superiority of our proposed TKD-Net approach. 相似文献
80.
In this paper, a rare-earth spectral traceability anti-counterfeiting detection technology is proposed. Configure rare-earth samples No.1, No.2 and No.3 with different doping ratios. The spectral signals of these three samples are collected and integrated into a sample library. The traceability anti-counterfeiting detection is to compare the spectral information of the samples to be tested with the established sample library by selecting specific wavelength points for light intensity values. If the sample to be measured meets the light intensity range of the established sample library at a specific wavelength point, the sample model will be output. If it does not meet the light intensity range, the sample to be tested is fake. After testing, the anti-counterfeit rate of samples No.1, No.2 and No.3 can reach 100%. This testing process does not destroy the sample, and the anti-counterfeit effect is unique and reliable. 相似文献