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101.
This paper investigates the exact and approximate spectrum assignment properties associated with realizable output-feedback pole-placement type controllers for single-input single-output linear time-invariant time-delay systems with commensurate point delays. The controller synthesis problem is discussed through the solvability of a set of coupled diophantine equations of polynomials. An extra complexity is incorporated to the above design to cancel extra unsuitable dynamics being generated when solving the above diophantine equations. Thus, the complete controller tracks any arbitrary prefixed (either finite or delaydependent) closed-loop spectrum. However, if the controller is simplified by deleting the above mentioned extra complexity, then the robust stability and approximated spectrum assignment are still achievable for a certain sufficiently small amount of delayed dynamics. Finally, the approximate spectrum assignment and robust stability problems are revisited under plant disturbances if the nominal controller is maintained. In the current approach, the finite spectrum assignment is only considered as a particular case to the designer‘s choice of a (delay-dependent) arbitrary spectrum assignment objective. 相似文献
102.
LIU Yan-Ping CHEN Zhao-Yang BA Wei-Zhen FAN Yan-Wei DU Yan-Zhao PAN Shi-Lie GUO Qi 《中国物理C(英文版)》2008,32(5)
The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity.Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-acoess and hazardous.In addition.optical fiber dosimeters are immune to electrical and radio-frequency interference.In this paper,a novel remote optical fiber radiation dosimeter is described.The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL.The measuring range of the dosimeter is from 0.1 to 100 Gy.The equipment is relatively simple and small in size,and has low power consumption.This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions. 相似文献
103.
在间接驱动惯性约束聚变的黑腔中,辐射烧蚀的高Z等离子体的流体力学运动过程对激光注入黑腔的效率、辐射场均匀性和通过诊断口的黑腔辐射温度诊断都有显著影响。为研究诊断口在黑腔辐射场中的等离子体缩口过程,用激光产生X光辐射加热低Z泡沫填充的金黑腔诊断口,以激光辐照钛平面靶产生的2~5 keV高能段窄能区X光作为背光源,用X光分幅相机获得了源靶和小孔靶两种靶型的小孔等离子体运动过程图像,研究了X光烧蚀的小孔等离子体的流体力学运动过程,探索了定量测量小孔等离子体面密度的空间分布与时间演化过程的实验诊断方法,初步给出小孔等离子体的面密度。 相似文献
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105.
Structural rearrangement and stiffening of hydrophobically modified supramolecular hydrogels during thermal annealing
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Chao Wang Clinton G. Wiener Yiming Yang R. A. Weiss Bryan D. Vogt 《Journal of Polymer Science.Polymer Physics》2017,55(13):1036-1044
Dynamic crosslinks formed by thermoreversible associations provide an energy dissipation mechanism to toughen hydrogels. However, the details of the organization of these crosslinks impact the hydrogel properties through constraints on the network chain conformation. The physical crosslinks generated by hydrophobic association of the 2‐(N‐ethylperfluorooctane‐sulfonamido)ethyl methacrylate (FOSM) groups in a random copolymer of N,N‐dimethylacrylamide (DMA) and FOSM provide a simple system to investigate how the hydrogel structure (as determined from small angle neutron scattering impacts the mechanical properties of the hydrogel. The initial hydration of the copolymer at 25 °C leads to a kinetically trapped structure with large‐scale heterogeneities. Heating the hydrogel at 60 °C, which is above the glass transition temperature for the FOSM domains, allows the hydrogel structure to rearrange to reduce the density of network defects and the structural heterogeneities. That effectively increases the crosslink density of the network, which stiffens the hydrogel and decreases the swelling at equilibrium at 25 °C. The processing history determines how the hydrophobes aggregate to form the physically crosslinked network, whose structure defines the mechanical properties of these hydrogels. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1036–1044 相似文献
106.
《Biomedical chromatography : BMC》2017,31(5)
Pulsatilla chinensis (Bunge) Regel is commonly used in Asia, and anemoside B4 (AB4) is its major saponin, with diverse pharmaceutical effects. Previous studies showed that intestinal flora plays an important role in the metabolism of herbs administered orally. In this study, the metabolic profile of AB4 with microflora in rat small and large intestines in vitro was investigated. Gut microflora was collected from different intestinal segments and anaerobically incubated with AB4 at 37°C for 24, 48, 72 and 96 h, respectively. A total of 10 metabolites were detected and identified by ultra‐ performance liquid chromatography/quadrupole time‐of‐flight mass spectrometry, involving the products of oxygenation and deglycosylation reactions. Gut microflora in the large intestine generated more comprehensive metabolic pathways, which appears to be attributable to the wider range of bacterial types and numbers of bacteria. Human cancer cell lines SMMC‐7721, Hela and MCF‐7 were treated with metabolite pools by MTT assay, together with M6 as the greatest deglycosylation product. As a result, M6 exhibited a reduction in cell viability of SMMC‐7721 with an IC50 value of 22.28 ± 1.26 μg/mL. The present study provided scientific evidence for AB4 metabolism in small and large intestines, which is helpful to reveal the active forms of AB4 in vivo . 相似文献
107.
Dr. Erin N. Hancock Prof. M. Kevin Brown 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(2):565-576
The ladderane family of natural products are well known for their linearly concatenated cyclobutane skeletal structure. Owing to their unique carbocyclic framework, several chemical syntheses have been reported since their discovery in 2002. The focus of this review is to showcase the novel tactics that have been used to generate the ladderane core and the challenges that are associated with the synthesis of these unusual and complex natural products. 相似文献
108.
Tamara Koledin 《Linear and Multilinear Algebra》2017,65(11):2187-2198
In this paper we focus on connected signed graphs of fixed number of vertices, positive edges and negative edges that maximize the largest eigenvalue (also called the index) of their adjacency matrix. In the first step we determine these signed graphs in the set of signed generalized theta graphs. Concerning the general case, we use the eigenvector techniques for getting some structural properties of resulting signed graphs. In particular, we prove that positive edges induce nested split subgraphs, while negative edges induce double nested signed subgraphs. We observe that our concept can be applied when considering balancedness of signed graphs (the property that is extensively studied in both mathematical and non-mathematical context). 相似文献
109.
110.
The design of the China Spallation Neutron Source (CSNS) low-energy beam transport (LEBT) line, which locates between the ion source and the radio-frequency quadrupole (RFQ), has been completed with the TRACE3D code. The design aims at perfect matching, primary chopping, a small emittance growth and sufficient space for beam diagnostics. The line consists of three solenoids, three vacuum chambers, two steering magnets and a pre-chopper. The total length of LEBT is about 1.74 m. This LEBT is designed to transfer 20 mA of H-pulsed beam from the ion source to the RFQ. An induction cavity is adopted as the pre-chopper.The electrostatic octupole steerer is discussed as a candidate. A four-quadrant aperture for beam scraping and beam position monitoring is designed. 相似文献