共查询到20条相似文献,搜索用时 78 毫秒
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应用Lukosz预校正模型算法可以校正波前畸变的低阶像差,缩小迭代算法的搜寻范围;应用自适应余弦衰减的随机并行梯度下降(AcSPGD)算法可以补偿波前畸变的高阶像差,提升迭代算法的校正精度。本文提出了一种基于预校正模型和AcSPGD算法的混合模型算法,并将其应用于无波前传感自适应光学系统中校正湍流大气产生的畸变波前,最后搭建实验光路验证了算法的有效性。结果表明,混合模型算法的校正速率是常用的随机并行梯度下降(SPGD)算法的3倍,且校正精度比传统的Lukosz模型算法更高,应用于无波前传感自适应光学系统中有效减小了光场波前的相位起伏,提高了远场光斑斯特列尔比(SR),使自由空间光通信(FSO)系统的通信性能得到有效提升。 相似文献
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输入信息测试不完备是结构动力测试中常遇到的问题,本文在回顾这方面文献的基础上,重点对预报-校正迭代算法进行了研究,针对该算法提出的第一类迭代过程,分别从部分输入未知和全部输入未知两方面进行讨论,从理论分析和数值算例说明了该迭代算法存在的不足,证明了学者们长期以来对该算法提出的疑问. 相似文献
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将Lissajous标定技术应用到相移干涉测量的相移算法(PSA)中,提出一种基于Lissajous标定技术的随机相移误差校正算法。该算法不需要计算各帧干涉图之间的实际相移量,直接用Lissajous标定和椭圆拟合的方法计算相移算法的相位提取误差(包括离焦、偏倚、相移量偏差)然后进行校正。数值模拟结果表明:该算法不需要迭代运算就能从大于3帧的带有随机相移误差的干涉图中有效恢复出正确的相位信息,运算时间少,计算精度高并且适合于所有的相移算法。实验结果表明:基于Lissajous标定技术的随机相移误差校正算法与现有的迭代随机相移算法(AIA)精度相当,但计算速度得到明显提升。 相似文献
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通过对常用图像拼接算法的研究,提出一种基于图像特征点的拼接算法,利用梯度方向特征点的数据,确定一组最合理的特征匹配,利用这一数据给出两幅图像间矩阵变换的初值,再利用迭代的方法校正,最终得到精确值,通过仿真结果验证算法的有效性。 相似文献
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本文提出了求解非线性耦合系统的一种迭代算法,这种方法是应用广泛拉氏乘子构造较正泛函,然后用变分理论最佳识别。这种方法对初近似不敏感,也没有“小参数”的限制,可广泛用于非线性振动问题。 相似文献
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通过摄像机自动旋转判读360°空间内的多台仪表是比较有优势的计算机视觉判读仪表方案,但由此造成的倾斜拍摄会使表盘画面严重畸变.因此设计了一种能够在任意拍摄角度下自动校正仪表图像畸变的判读算法.首先通过设计定位校正板从背景中自动提取表盘图像,然后以此板上的校正标识为基础利用LM算法迭代建立8参数透视畸变模型将表盘校正回真实形状,实现仪表高精度判读. 相似文献
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计算结构可靠度指标的修正迭代算法 总被引:1,自引:0,他引:1
针对一次二阶矩法可靠度指标分析中验算点的计算问题,提出一种新的修正迭代算法。基于对文献已有迭代算法无法收敛原因的认识和讨论,提出一个迭代迂回振荡的判据,并在检测到迭代迂回振荡后,在经典的HL-RF迭代算法的基础上采用插值技术引入验算点的校正解。数值算例表明:该修正迭代算法一定程度上克服了迭代过程迂回振荡的问题,与经典的HL-RF算法以及文献已有算法相比,在迭代的收敛性和稳定性方面具有优势。 相似文献
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目的为了解决当前航空行李码放流程中存在的劳动密集、效率低下的问题,开展行李码放算法研究。方法搭建含有重量、体积和货舱空间约束的航空行李码放数学模型,采用聚类、排序、关键点构建策略,设计一种K-means聚类与"关键点"思想相结合的组合式算法。结果采用100件真实旅客行李数据进行了实验,结果表明算法给出的布局方案规划合理,垛型左右两侧质量之差低于1%,满足了货舱的空间约束与载重平衡约束。结论算法具备在复杂环境下得到优良布局方案的能力,K-means聚类的引入也将机器学习领域的聚类算法引入装箱问题,架起了机器学习算法与传统装箱算法的桥梁,为今后装箱问题算法的设计提供了一条新思路。 相似文献
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Ratnasingam S Collins S Hernández-Andrés J 《Journal of the Optical Society of America. A, Optics, image science, and vision》2011,28(4):541-547
In this paper, the results of an investigation of the possibility of extending "color constancy" to obtain illuminant-invariant reflectance features from data in the near-ultraviolet (UV) and near-infrared (IR) wavelength regions are reported. These features are obtained by extending a blackbody-model-based color constancy algorithm proposed by Ratnasingam and Collins [J. Opt. Soc. Am. A27, 286 (2010)] to these additional wavelengths. Ratnasingam and Collins applied the model-based algorithm in the visible region to extract two illuminant-invariant features related to the wavelength-dependent reflectance of a surface from the responses of four sensors. In this paper, this model-based algorithm is extended to extract two illuminant-invariant reflectance features from the responses of sensors that cover the visible and either the near-UV or near-IR wavelength. In this investigation, test reflectance data sets are generated using the goodness-fitness coefficient (GFC). The appropriateness of the GFC for generating the test data sets is demonstrated by comparing the results obtained with these data with those obtained from data sets generated using the CIELab distance. Results based upon the GFC are then presented that suggest that the model-based algorithm can extract useful features from data from the visible and near-IR wavelengths. Finally, results are presented that show that, although the spectrum of daylight in the near UV is very different from a blackbody spectrum, the algorithm can be modified to extract useful features from visible and near-UV wavelengths. 相似文献
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Czesław Smutnicki 《OR Spectrum》1998,20(4):229-235
Problems with blocking (limited intermediate storage space) are used frequently for modelling and scheduling just-in-time and flexible manufacturing systems. In this paper, an approximation algorithm is presented for the problem of finding the minimum makespan in a two-machine permutation flow-shop scheduling problem with the mediating buffer of finite capacity. The algorithm is based on the tabu search approach supported by the reduced neighborhood, search accelerator and technique of back jumps on the search trajectory. Due to some special properties, the proposed algorithm provides makespans very close to optimal in a short time. It has been shown that this algorithm outperforms all known approximation algorithms for the problem stated. 相似文献
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In this paper the solution of the specialized measuring system for electrocardiography (ECG) signal recording and introductory recognition is presented. The project aims at designing the complete PC-based Virtual Instrument as a "testing platform" for acquisition, processing, presenting, and distributing ECG data. A new design involving the latest technique in signal simulation was developed to create a controllable model of the electrocardiography signal. Then it was implemented for testing of the developed QRS detection algorithm, based on the time-frequency analysis method. The processing stage involving discrete wavelet transform was used to detect QRS complexes in the ECG signal. By using the controlled signal model and the real ones, the algorithm was shown to be advantageous in reducing ventilation artifacts and motion noise, resulting in good accuracy. 相似文献
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Diffraction data are used to develop 300-K models of the amorphous Ni62Nb38 and Ni44Nb56 alloys using a hybridization algorithm, in which the force functions for each atomic pair are linear combinations of those generating the structure of the alloy at 0 and 300 K. These force functions are found using the Schommers algorithm at 300 K and the coordination number comparison algorithm (proposed in this work) at 0 K. The pair correlation functions thus found agree well with the diffraction data. The calculated vibrational densities of states for the Ni and Nb atoms in the amorphous alloys studied are in reasonable agreement with inelastic neutron scattering data. The calculated heat capacity of Ni62Nb38 agrees well with experiment, while that of Ni44Nb56 is lower than the reported values. 相似文献
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The aim of this work is to present a computationally efficient algorithm to simulate the butt curl deformation. In our previous articles [1, 2] the nonlinearities due to the viscoplastic law and the contact condition with the bottom block were solved by means of duality methods involving two multipliers. In [1] these multipliers were computed with a fixed point algorithm and in [2] with a generalized Newton’s method. In this work we improve the viscoplastic algorithm by means of a generalized duality method with variable parameters. We will present numerical results showing the applicability of the resultant algorithm to casting processes. 相似文献
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Thaer M. Dieb Shenghong Ju Kazuki Yoshizoe Zhufeng Hou Junichiro Shiomi 《Science and Technology of Advanced Materials》2013,14(1):498-503
AbstractComplex materials design is often represented as a black-box combinatorial optimization problem. In this paper, we present a novel python library called MDTS (Materials Design using Tree Search). Our algorithm employs a Monte Carlo tree search approach, which has shown exceptional performance in computer Go game. Unlike evolutionary algorithms that require user intervention to set parameters appropriately, MDTS has no tuning parameters and works autonomously in various problems. In comparison to a Bayesian optimization package, our algorithm showed competitive search efficiency and superior scalability. We succeeded in designing large Silicon-Germanium (Si-Ge) alloy structures that Bayesian optimization could not deal with due to excessive computational cost. MDTS is available at https://github.com/tsudalab/MDTS. 相似文献
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Parallel computation of a damage localization problem using parallel multifrontal solver 总被引:1,自引:0,他引:1
In this paper, nonlinear parallel structural analyses are performed using a distributed memory sparse direct multifrontal linear solver. The linear solver is fully parallel, working with substructures determined by a parallel graph partitioner. The parallel performance of the nonlinear parallel algorithm is demonstrated using damage localization problems for two and three dimensional crack models. Convergence studies of the predicted local variation of damage at the crack tip are performed using discretizations with up to one million degrees of freedom. Implementation issues for damage localization problems are discussed, including the selection of independent variables and the use of Riks continuation method.We acknowledge the financial support of Ministry of Science and Technology by National Research Laboratory program. (grant number 00-N-NL-01-C-026) 相似文献
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L. Gournay J. J. Risler 《Applicable Algebra in Engineering, Communication and Computing》1993,4(4):239-252
In this paper we describe an algorithm of construction of a roadmap for a compact semi-algebraic setS Rn, which is similar to the algorithm of [3], but which is simpler in the sense that it does not need the use of Whitney stratifications, and more general because it accepts as input any compact semi-algebraic set. The complexity of this algorithm is measured in terms of the numberk of polynomials definingS, their maximum degreed, and the number of variablesn. With respect to those measures, our algorithm runs in time
. The goal of this paper is not a strengthening of the previous results (similar bounds of complexity are obtained in [5] and [13], even for a non-compact set), but more a new approach, and we hope the efficiency of the algorithm. 相似文献