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81.
Herbert Fischer 《Computational Optimization and Applications》1992,1(3):327-344
This paper is concerned with automatic differentiation methods for computing the reduced gradient M
t
G and the reduced Hessian matrix M
t
HM. Hereby G is the gradient and H is the Hessian matrix of a real function F of n variables, and M is a matrix with n rows and k columns where kn. The reduced quantities are of particular interest in constrained optimization with objective function F. Two automatic differentiation methods are described, a standard method that produces G and H as intermediate results, and an economical method that takes a shortcut directly to the reduced quantites. The two methods are compared on the basis of the reqired computing time and storage. It is shown that the costs for the economical method are less than (k
2+3k+2)/(n
2+3n+2) times the expenses for the standard method. 相似文献
82.
Two major side-products and a desired peptide (each was one-third) were found in analysis of a synthesized fragment (65-74) of the acyl carrier protein by a solid-phase automatic peptide synthesizer. The peptide mixtures were separated and collected by HPLC. Each isolated peptide was characterized via amino-acid composition analysis, mass spectra and specific peptide-bond cleavage to prove the sequence. Each by-product had one amino-acid missing (72Ile and 73Asn, respectively) from the sequence of ACP(65-74). 相似文献
83.
食品安全问题一直是社会和广大群众关注的焦点问题,食品安全现状较为严峻,因此实现食品中有害物质的快速检测具有重要的实际意义。合成色素是一种常见的食品添加剂,然而合成色素的超标添加和非法添加依旧是食品安全中的重要问题之一,极大地危害人民群众的身体健康和食品工业的健康发展。常见的合成色素检测方法,均存在耗时长、费用高等缺点,不适应于合成色素的实时监测和快速筛查。为克服传统方法的缺点,提出利用表面增强拉曼光谱检测技术对合成色素进行检测,该方法具有检测速度快、检测灵敏度高等优点,能够达到现场实时检测的目的。此外,由于拉曼检测方法往往依赖于复杂的样品前处理操作,而常见的固相萃取技术一般依赖于人工操作,过程复杂且耗时较长,严重影响食品快速检测效率。因此,开发了一种全自动固相萃取装置,通过设计嵌入式硬件电路系统及其软件,精确控制蠕动泵流速和多路阀门开关实现了活化、上样、淋洗、洗脱四个步骤的全自动操作和参数控制,从而达到食品样品的全自动快速固相萃取。在实验部分,配制不同专利蓝V浓度的果汁饮料,然后利用该装置对果汁中的专利蓝V进行前处理,对萃取柱填料和萃取中各个步骤的时间和试剂进行了合理的选择,利用表面增强拉曼光谱检测技术成功地检测了合成色素中的专利蓝V。实验结果表明,所研制的自动固相萃取装置对比传统手工萃取,每个样品节省了近一半的萃取时间(10 min降为5 min)且能够同时处理5个样品,萃取时间稳定不易受人为因素影响,从而极大地提高了萃取效率和稳定性。此外,通过自动萃取获得的样品,对比手工萃取操作,因其受外界干扰相对较小,能够得到更强的拉曼光谱信号(约增强50%),获得了满意的萃取效果。对不同浓度的专利蓝V样品的结果显示,该方法能够实现检出质量浓度在0.5 mg·L-1水平,可有效满足现场监测需求。具有快速、方便、灵敏度高等特点。 相似文献
84.
85.
对基于连接时序分类准则(connectionist temporal classification,CTC)的端到端声学建模方法进行研究和优化。研究分析了不同声学特征、建模单元以及神经网络结构对CTC声学模型性能的影响,针对CTC模型中blank符号共享导致的建模缺陷提出了建模单元相关的非共享blank方法进行改进,并引入融合建模单元关联信息的模型初始化方法进一步提高CTC模型的性能。在300小时标准英文数据集Switchboard的实验结果显示,结合非共享blank、时延神经网络以及融合建模单元关联信息的初始化方法,CTC声学模型相对于基线系统在词错误率上取得绝对1.1%的下降,同时在训练速度上取得3.3倍的提高,实验结果证明本文针对端到端声学建模提出的优化方法是有效的。 相似文献
86.
This paper presents an automatic scoring method for p53 immunostained tissue images of oral cancer that consist of tissue image segmentation, splitting of clustered nuclei, feature extraction and classification. The tissue images are segmented using entropy thresholding technique in which the optimum threshold value to each color component is obtained by maximizing the global entropy of its gray-level co-occurrence matrix and clustered cells are separated by selectively applying marker-controlled watershed transform. Cell nuclei feature is extracted by maximal separation technique (MS) based on blue component of tissue image and subsequently, each cell is classified into one of four categories using multi-level thresholding. Finally, IHC score of tissue images have been determined using Allred method. A statistical analysis is performed between immuno-score of manual and automatic method, and compared with the scores that have obtained using other MS techniques. According to the performance evaluation, IHC score based on blue component that has high correlation coefficients (CC) of 0.95, low mean difference (MD) of 0.15, and a very close range of 95% confidence interval with manual scores. Therefore, automatic scoring method presented in this paper has high potential to help the pathologist in IHC scoring of tissue images. 相似文献
87.
的:灰阶响应时间需要测试不同灰阶之间切换需要的时间,这样测试的数据量是非常大的。如:9级灰阶,需要的的测试数据量就是9*(9-1)=72个。仅仅靠手动测试已经很难完成该测试。需要自动化的测量方法才能完成。方法:对LCD的灰阶响应时间自动测量进行了研究,用综合测试仪(DMS)与FPGA系统结合的方案完成灰阶响应时间的自动测量,可以快速准确的测试灰阶响应时间。结果:采用这个方案可以在无需额外购买测试设备的情况下几分钟内测试一组灰阶响应时间,测试基准采用DMS设备,所以测试的准确率高。结论:该自动测试方案对于LCD灰阶响应时间的测量和研究具有很强的实用价值。 相似文献
88.
The numerical solution of nonlinear equation systems is often achieved by so-called quasi-Newton methods. They preserve the
rapid local convergence of Newton’s method at a significantly reduced cost per step by successively approximating the system
Jacobian though low-rank updates. We analyze two variants of the recently proposed adjoint Broyden update, which for the first
time combines the classical least change property with heredity on affine systems. However, the new update does require, the
evaluation of so-called adjoint vectors, namely products of the transposed Jacobian with certain dual direction vectors. The
resulting quasi-Newton method is linear contravariant in the sense of Deuflhard (Newton methods for nonlinear equations. Springer,
Heidelberg, 2006) and it is shown here to be locally and q-superlinearly convergent. Our numerical results on a range of test problems demonstrate that the new method usually outperforms
Newton’s and Broyden’s method in terms of runtime and iterations count, respectively.
Partially supported by the DFG Research Center Matheon “Mathematics for Key Technologies”, Berlin and the DFG grant WA 1607/2-1. 相似文献
89.
《Stochastic Processes and their Applications》2020,130(8):5006-5036
We study semi-linear elliptic PDEs with polynomial non-linearity in bounded domains and provide a probabilistic representation of their solution using branching diffusion processes. When the non-linearity involves the unknown function but not its derivatives, we extend previous results in the literature by showing that our probabilistic representation provides a solution to the PDE without assuming its existence. In the general case, we derive a new representation of the solution by using marked branching diffusion processes and automatic differentiation formulas to account for the non-linear gradient term. We consider several examples and estimate their solution by using the Monte Carlo method. 相似文献
90.
《Indagationes Mathematicae》2017,28(4):863-883
We extend and improve our earlier results on automatic regularity of continuous algebra homomorphisms between Riesz algebras of regular operators. 相似文献