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991.
992.
Nobuaki Obata 《Acta Appl Math》2000,63(1-3):283-291
An infinite-dimensional extension of a coherent state representation is discussed within the framework of white noise calculus. The exponential vectors (unnormalized coherent states) and the complex Gaussian integral play a role in such representations of a white noise function and of a white noise operator. 相似文献
993.
We study the phase portrait of a harmonic oscillator with friction for the case in which random perturbations of white noise type expressed in the Itô form act at a certain angle to the phase velocity vector. 相似文献
994.
An experimental approach to two-dimensional, viscoelastic, steadily moving rolling contact is described. The photoviscoelastic technique is employed for the analysis of rolling contact stresses between a viscoelastic plate and a rigid rolling cylinder in which the principal axes of stress, strain and birefringence are not coincident with each other. Using an elliptically polarized white light, the distribution of isochromatic fringe order and the principal axes of birefringence at an instant are determined from a single photoviscoelastic image. The time variations of the differences of the principal stresses and strains, as well as their directions, are obtained by use of the optical constitutive equations of photoviscoelasticity. The experimental results involving the time variation of the stresses around the contact surface and their distributions are analyzed. 相似文献
995.
L. Gruber J.P. Holder B.R. Beck J. Steiger J.W. McDonald J. Glassman H. DeWitt D.A. Church D. Schneider 《Hyperfine Interactions》2000,127(1-4):215-222
The investigation of highly charged ion Coulomb crystallization in mixed strongly coupled plasmas is of interest in many areas:
white dwarf astrophysical plasmas are believed to have very similar thermodynamic properties, cold highly charged ions can
be used as an object for high precision laser spectroscopy of fine and hyperfine transitions in the visible due to the absence
of Doppler broadening and, an entirely new area of research is the potential application to highly charged ion based quantum
computing schemes.
We report the formation of such plasmas in a cryogenic Penning trap. These plasmas consisting of many species including Be+ and Xe44+ or Be+ and Xe15+ ions, are formed at a temperature of less than 4 K. The temperatures were obtained by applying a laser based sympathetic
cooling scheme. The determination of the temperature and density from the laser resonance width and the fluorescence imaging
of the Be+ clouds, respectively, yields a Coulomb coupling constant for the centrifugally separated Xe plasma high enough for crystallization.
A molecular dynamics code, developed just for this purpose, was run to clarify the understanding of these plasmas and it was
possible to show consistency between experiment and simulation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
996.
以黄冶窑四个时期的白瓷样品作为研究对象,利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对样品进行分析,结果表明:黄冶窑白瓷胎的物相基本相同,主要是莫来石、α石英和方石英、未熔石英和少量的粘土相;黄冶窑白瓷釉中有气泡存在,釉中气泡为圆形,釉中存在微米级的针状或柱状钙长石晶体,釉存在分相结构,且分相结构与析晶相伴而生;黄冶窑白瓷胎中有气孔、未熔的石英颗粒、较大的Ti颗粒、莫来石晶体和石英晶体。The white porcelain samples of the four periods of Huangye kiln were studied in this paper, and the samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the material phase is basically the same of the white porcelain bodies from Huangye kiln, and mainly mullite, alpha quartz and cristobalite, unmelted quartz and a small amount of clay phase; There are some round bubbles in HuangYe kiln white porcelain, glazes, so are some feldspathic crystals with micro-level needles or columnar. It is evident to observe phase separation structure, which is accompanied by the birth. Apart from some pores, unfused quartz particles, larger Ti particles, mullite crystals and quartz crystals can also be found in the embryo of Huangye kiln white porcelain. 相似文献
997.
998.
Daniela Fracassetti Sara Limbo Natalia Messina Luisa Pellegrino Antonio Tirelli 《Molecules (Basel, Switzerland)》2021,26(17)
Light exposure of white wine can cause a light-struck taste (LST), a fault induced by riboflavin (RF) and methionine (Met) leading to the formation of volatile sulfur compounds (VSCs), including methanethiol (MeSH) and dimethyl disulfide (DMDS). The study aimed to investigate the impact of different antioxidants, i.e., sulfur dioxide (SO2), glutathione (GSH) and chestnut tannins (CT), on preventing LST in model wine (MW) and white wine (WW), both containing RF and Met. Both MW and WW samples were added with the antioxidants, either individually or in different combinations, prior to 2-h light exposure and they were stored in the dark for 24 months. As expected, the light induced the degradation of RF in all the conditions assayed. Met also decreased depending on the antioxidants added. The presence of antioxidants limited the formation of LST as lower concentrations of VSCs were found in both MW and WW samples. In the latter matrix, neither MeSH nor DMDS were detected in the presence of CT, while only DMDS was found in WW+GSH, WW+SO2+GSH and WW+CT+SO2 samples at a concentration lower than the perception thresholds. Considering the antioxidants individually, the order of their effectiveness was CT ≥ GSH > SO2 in WW under the adopted experimental conditions. The results indicate tannins as an effective enological tool for preventing LST in white wine and their use will be further investigated in different white wines under industrial scale. 相似文献
999.
1000.
以镉的脂肪酸盐和分散在三辛基膦中的硒单质分别作为镉和硒的前体,采用十二烷基硫醇做“成核剂”,十二烷基胺为活化剂,在非配位溶剂十八碳烯中,实现了连续尺寸高质量魔幻尺寸半导体纳米簇(CdSe)的合成。所得CdSe纳米簇的形态和光学性质分别通过透射电子显微镜、紫外可见吸收光谱、荧光激发光谱、荧光发射光谱及时间分辨的荧光光谱测试技术进行了表征和测定。该系列CdSe纳米簇具有良好的室温荧光性质,能够得到较强的以往只有低温(5~200K)下才能探测到的荧光光谱。所得发射光谱大部分为表面缺陷导致的黄光发射。部分尺寸的纳米簇能够实现白光发射,其CIE坐标为(0.339,0.340),为白光光源的开发提供了备选材料。 相似文献