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21.
We apply the theory developed in quantum cosmology to a model of charged generalized Brans–Dicke gravity. This is a quantum model of gravitation interacting with a charged Brans–Dicke type scalar field which is considered in the Pauli frame. The Wheeler–DeWitt equation describing the evolution of the quantum Universe is solved in the semiclassical approximation by applying the WKB approximation. The wave function of the Universe is also obtained by applying both the Vilenkin-like and the Hartle–Hawking-like boundary conditions. We then make predictions from the wave functions and infer that the Vilenkin's boundary condition is more reasonable in the Brans–Dicke gravity models leading a large vacuum energy density at the beginning of the inflation.  相似文献   
22.
Kelvin−Helmholtz (KH) instability is a fundamental fluid instability that widely exists in nature and engineering. To better understand the dynamic process of the KH instability, the influence of the tangential velocity on the compressible KH instability is investigated by using the discrete Boltzmann method based on the nonequilibrium statistical physics. Both hydrodynamic and thermodynamic nonequilibrium (TNE) effects are probed and analyzed. It is found that, on the whole, the global density gradients, the TNE strength and area firstly increase and decrease afterwards. Both the global density gradient and heat flux intensity in the vertical direction are almost constant in the initial stage before a vortex forms. Moreover, with the increase of the tangential velocity, the KH instability evolves faster, hence the global density gradients, the TNE strength and area increase in the initial stage and achieve their peak earlier, and their maxima are higher for a larger tangential velocity. Physically, there are several competitive mechanisms in the evolution of the KH instability. (i) The physical gradients increase and the TNE effects are strengthened as the interface is elongated. The local physical gradients decrease and the local TNE intensity is weakened on account of the dissipation and/or diffusion. (ii) The global heat flux intensity is promoted when the physical gradients increase. As the contact area expands, the heat exchange is enhanced and the global heat flux intensity increases. (iii) The global TNE intensity reduces with the decreasing of physical gradients and increase with the increasing of TNE area. (iv) The nonequilibrium area increases as the fluid interface is elongated and is widened because of the dissipation and/or diffusion.  相似文献   
23.
The characteristics of Al2O3 film grown by atomic‐layer deposition as blocking layer with and without fluorine plasma treatment were investigated based on a capacitor structure of Al/Al2O3/TaON/SiO2/Si. The physical structure was studied by transmission electron microscopy, and the chemical composition of the blocking layer was analyzed by X‐ray photoelectron spectroscopy and secondary ion mass spectroscopy. Moreover, the surface roughness of the blocking layer was investigated by atomic force microscopy. Compared with a capacitor with Al2O3 blocking layer, the one with fluorinated Al2O3 displayed higher programming/erasing speeds, better endurance property and better charge retention characteristic because the fluorination could reduce excess oxygen and traps in the blocking layer, thus forming a larger barrier height at the interface between the charge‐trapping layer and the blocking layer. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
24.
A near infrared reflective (NIR, nickel antimony titanium yellow rutile) pigment filler was incorporated into a polyethylene terephthalate (PET) matrix via a melt blending approach to increase the infrared reflection of PET and limit the thermal heat accumulation in light of environmental and energy conservation concerns. Two different types of surface modifiers, polyethylene glycol (PEG) and cetyltrimethylammonium bromide (CTAB), were used to modify the NIR surface, as NIR–PEG and NIR–CTAB fillers, to investigate the surface modification effect. Fourier transform infrared spectroscopy (FTIR), a Zetasizer, and electron spectroscopy for chemical analysis (ESCA) results suggested a successful adsorption of the organic modifiers onto the NIR surface. Thermogravimetric analysis indicated a higher adsorption degree for the CTAB modifier than the PEG modifier due to the electronic interaction between CTAB and NIR. The thermal crystallization temperature (Tc) for neat NIR-filled samples decreased with increasing NIR content within the PET matrix at first, up to 9°C, but then tended to increase again up to a measurable difference of 6°C with respect to pure PEG, indicating the promotion of the crystallization kinetics of the neat NIR within the PET matrix. On the other hand, a decrease in Tc for all NIR-CTAB or NIR-PEG loadings was found, with the depression close to 10°C for all NIR-CTAB samples regardless of the loading. CTAB modified NIR gave the highest improvement in tensile strength and strain at break in comparison with NIR and NIR-PEG filled samples. The near infrared reflection values of modified PET were higher than those of neat PET. The reflection values appeared to be the highest for some concentrations of the NIR-CTAB filled samples, but were of similar orders of magnitude with those for NIR or NIR-PEG filled samples.  相似文献   
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26.
The theory of anisotropic sputtering published in Phys. Rev. B 71(2), 026101 (2005) and Radiat. Effects Defects Solids 159(5), 301 (2004) has been modified and used to calculate the sputtering yield energy distributions for copper, tungsten, and aluminum targets bombarded by low-energy argon ion. As usual, the electronic stopping is ignored in the analysis. The present theory (modified Sigmund’s theory) has been shown to fit the corresponding experimental results of sputtering yield energy distributions well, except for the cases where the larger ion incident angle and larger sputtering emission angles were considered. The larger discrepancy between the present theory and the experimental result in the latter cases is probably due to the influence of direct recoil atoms on the energy spectrum. Compared with Falcone’s analytical theory, the present theory can reproduce much better experimental results of sputtering phenomena. The fact clearly demonstrates the intrinsic relation between the ion–energy dependence of the total sputtering yield and the sputtering yield energy distribution and suggests the great importance of momentum deposited on the target surface in the physical sputtering  相似文献   
27.
Smart windows are crucial to dynamic control over light transmission to fulfill various demands in energy saving, privacy, and information display; however, most present technologies still perform a single function (often tint or haze adjustment) and require continuous electricity for operation. In this study, novel self-assembled ionic liquid crystals (ILCs) doped with negative cholesteric liquid crystals (CLCs) to offer electrically switchable and stable scattering-mode light modulators are presented. The novel smectic A phase based on the ILCs exhibits high solubility in the adopted nematics, enhancing the LC device's performance in several ways, including improved homogeneity, stable alignment quality, prolonged stability, and simplified fabrication. The LC device can potentially offer a dynamically rapid switching function between stable transparent (imperfect fingerprint textures) states and stable scattering (focal conic textures with small domains) states by using external stimuli and highly maintained multistable states for prolonged periods, even when the external stimuli are removed. The LC device also offers polarization-independent scattering and transparent-mode LC light modulators, low operating voltage, excellent contrast, and broad viewing angles. Its versatility and outstanding field-off stability make it ideal for various applications such as smart lighting, building climate control, energy-saving displays, and augmented reality (AR) glasses.  相似文献   
28.
QiuHong Wang  Abdusalam Abdukerim  Wei Chen  Xun Chen  YunHua Chen  XiangYi Cui  YingJie Fan  DeQing Fang  ChangBo Fu  LiSheng Geng  Karl Giboni  Franco Giuliani  LinHui Gu  XuYuan Guo  Ke Han  ChangDa He  Di Huang  Yan Huang  YanLin Huang  Zhou Huang  Peng Ji  XiangDong Ji  YongLin Ju  YiHui Lai  Kun Liang  HuaXuan Liu  JiangLai Liu  WenBo Ma  YuGang Ma  YaJun Mao  Yue Meng  Parinya Namwongsa  KaiXiang Ni  JinHua Ning  XuYang Ning  XiangXiang Ren  ChangSong Shang  Lin Si  AnDi Tan  AnQing Wang  HongWei Wang  Meng Wang  SiGuang Wang  XiuLi Wang  Zhou Wang  MengMeng Wu  ShiYong Wu  JingKai Xia  MengJiao Xiao  PengWei Xie  BinBin Yan  JiJun Yang  Yong Yang  ChunXu Yu  Jumin Yuan  Dan Zhang  HongGuang Zhang  Tao Zhang  Li Zhao  QiBin Zheng  JiFang Zhou  Ning Zhou  XiaoPeng Zhou 《中国科学:物理学 力学 天文学(英文版)》2020,(3):54-63
In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.  相似文献   
29.
AnN-person noncooperative discounted vector-valued game with a metric space is investigated. We define aD-convex equilibrium point and prove that aD-convex equilibrium point exists in this game system. A modified version of the original game system is formulated so that an equilibrium point of the modified version is aD-convex equilibrium point of the original game system. Under appropriate conditions, the converse holds in the sense that aD-convex equilibrium point is also an equilibrium point of the modified game system.  相似文献   
30.
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