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排序方式: 共有129条查询结果,搜索用时 15 毫秒
81.
强韧化材料的细观力学设计 总被引:4,自引:1,他引:3
本文主要阐述强韧化材料细观力学设计的基本概念和方法、力学模型和关键技术.探讨建立材料优化设计模型的可能途径.特别强调面向计算机的材料性能定量设计方法和材料细观力学设计的软件系统.评述当前在该领域内的若干研究进展 相似文献
82.
A CAD oriented quasi-analytical large-signal drain current model for 4H-SiC MESFETs 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper reports that a 4H-SiC MESFET (Metal Semiconductor Field
Effect Transistor) large signal drain current model based on
physical expressions has been developed to be used in CAD tools. The
form of drain current model is based on semi-empirical MESFET model,
and all parameters in this model are determined by physical
parameters of 4H-SiC MESFET. The verification of the present model
embedded in CAD tools is made, which shows a good agreement with
measured data of large signal DC I-V characteristics, PAE (power
added efficiency), output power and gain. 相似文献
83.
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85.
Chao Li Chuan Yu Liangjin Xue 《International Journal of Infrared and Millimeter Waves》2001,22(4):627-638
Radial stubs are a superior choice over low characteristic impedance rectangular stubs in terms of providing an accurate localized zero-impedance reference point and maintaining a low input impedance value over a wide frequency range. In this paper, knowledge-based artificial neural networks are used to model the microstrip radial stubs. Using space-mapping technology and Huber optimization make the neural network models for radial stubs decrease the number of training data, improve generalization ability, and reduce the complexity of the neural network topology with respect to the classical neuromodeling approach. The neural networks are developed for design and optimization of radial stubs, which are robust both from the angle of time of computation and accuracy. 相似文献
86.
87.
Caleb Kinsey Tian Lu Alyssa Deiss Kim Vuolo Lee Klein Richard R. Rustandi John W. Loughney 《Electrophoresis》2022,43(9-10):1091-1100
For many years, lipid nanoparticles (LNPs) have been used as delivery vehicles for various payloads (especially various oligonucleotides and mRNA), finding numerous applications in drug and vaccine development. LNP stability and bilayer fluidity are determined by the identities and the amounts of the various lipids employed in the formulation and LNP efficacy is determined in large part by the lipid composition which usually contains a cationic lipid, a PEG-lipid conjugate, cholesterol, and a zwitterionic helper phospholipid. Analytical methods developed for LNP characterization must be able to determine not only the identity and content of each individual lipid component (i.e., the parent lipids), but also the associated impurities and degradants. In this work, we describe an efficient and sensitive reversed-phase chromatographic method with charged aerosol detection (CAD) suitable for this purpose. Sample preparation diluent and mobile phase pH conditions are critical and have been optimized for the lipids of interest. This method was validated for its linearity, accuracy, precision, and specificity for lipid analysis to support process and formulation development for new drugs and vaccines. 相似文献
88.
Heikki Haario Aki Kallonen Marko Laine Esa Niemi Zenith Purisha Samuli Siltanen 《Mathematical Methods in the Applied Sciences》2017,40(18):6649-6669
A two‐dimensional sparse‐data tomographic problem is studied. The target is assumed to be a homogeneous object bounded by a smooth curve. A nonuniform rational basis splines (NURBS) curve is used as a computational representation of the boundary. This approach conveniently provides the result in a format readily compatible with computer‐aided design software. However, the linear tomography task becomes a nonlinear inverse problem because of the NURBS‐based parameterization. Therefore, Bayesian inversion with Markov chain Monte Carlo sampling is used for calculating an estimate of the NURBS control points. The reconstruction method is tested with both simulated data and measured X‐ray projection data. The proposed method recovers the shape and the attenuation coefficient significantly better than the baseline algorithm (optimally thresholded total variation regularization), but at the cost of heavier computation. 相似文献
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A mixed-mode chromatography coupled with charged aerosol detector (CAD) method was developed in this work to simultaneously determine pharmaceutical counterions including both inorganic ions and organic ions in the forms of cations and anions. 25 commonly used pharmaceutical ions were studied and simultaneously separated within 20 min by this single method. A silica based mixed-mode column with reversed-phase/cation-exchange/anion-exchange modes was used. It provides reversed-phase, strong cation-exchange and weak anion-exchange properties at the same time. It also provides the HILIC behavior at high percentage of organic solvent. The effects of mobile-phase organic strength, buffer ions, ionic strength, pH and column temperature have been investigated to optimize the method as well as to understand the retention and separation mechanisms. Conventional HPLC system was used and no special chromatography system is needed. The presented method has been employed successfully for screening and quantitative analysis of counterions, unknown ionic impurities and salts in active pharmaceutical ingredients and in process control samples with excellent accuracy, precision and sensitivity. This method provides a simple, fast and generic approach to speed up pharmaceutical research and development process and enhance lab efficiency. The similar methodologies can be applied to other ion analysis. 相似文献