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991.
992.
By taking the influence of optical phonon modes into account, this paper
adopts the dielectric continuum phonon model and force balance equation
to investigate the electronic mobility parallel to the interfaces for
AlAs/GaAs semiconductor quantum wells (QWs) under hydrostatic
pressure.
The scattering
from confined phonon modes, interface phonon modes and half-space
phonon modes are analysed and the dominant scattering mechanisms in
wide and narrow QWs are presented. The temperature dependence of the
electronic mobility is also studied in the temperature range of
optical phonon scattering being available. It is shown that the
electronic mobility reduces obviously as pressure increases from 0 to
4GPa, the confined longitudinal optical (LO) phonon modes play an
important role in wide QWs, whereas the interface optical
phonon modes are dominant in
narrow QWs, the half-space LO phonon modes hardly influence the electronic
mobility expect for very narrow QWs. 相似文献
993.
Study of total ionizing dose radiation effects on enclosed gate transistors in a commercial CMOS technology 下载免费PDF全文
This paper studies the total ionizing dose radiation effects on MOS
(metal-oxide-semiconductor) transistors with normal and enclosed gate
layout in a standard commercial CMOS (compensate MOS) bulk process.
The leakage current, threshold voltage shift, and transconductance of
the devices were monitored before and after $\gamma $-ray
irradiation. The parameters of the devices with different layout
under different bias condition during irradiation at different total
dose are investigated. The results show that the enclosed layout not
only effectively eliminates the leakage but also improves the
performance of threshold voltage and transconductance for NMOS
(n-type channel MOS) transistors. The experimental results also
indicate that analogue bias during irradiation is the worst case for
enclosed gate NMOS. There is no evident different behaviour observed
between normal PMOS (p-type channel MOS) transistors and enclosed
gate PMOS transistors. 相似文献
994.
Properties of field quantum entropy evolution in the Jaynes--Cummings model with initial squeezed coherent states field 下载免费PDF全文
The properties of the field quantum entropy evolution in a system of
a single-mode squeezed coherent state field interacting with a
two-level atom is studied by utilizing the complete quantum theory,
and we focus our attention on the discussion of the influences of
field squeezing parameter $\gamma $, atomic distribution angle
$\theta $ and coupling strength $g$ between the field and the atom
on the properties of the evolution of field quantum entropy. The
results obtained from numerical calculation indicate that the
amplitude of oscillation of field quantum entropy evolution
decreases with the increasing of squeezing parameter $\gamma $, and
that both atomic distribution angle $\theta $ and coupling strength
$g$ between the field and the atom can influence the periodicity of
field quantum entropy evolution. 相似文献
995.
In this paper an efficient quantum secure direct communication (QSDC) scheme with
authentication is presented, which is based on quantum entanglement and
polarized single photons. The present protocol uses Einstein--Podolsky--Rosen
(EPR) pairs and polarized
single photons in batches. A particle of the EPR pairs is retained
in the sender's station, and the other is transmitted forth and back
between the sender and the receiver, similar to the `ping--pong'
QSDC protocol. According to the shared information beforehand, these
two kinds of quantum states are mixed and then transmitted via a
quantum channel. The EPR pairs are used to transmit secret messages
and the polarized single photons used for authentication and
eavesdropping check. Consequently, because of the dual contributions
of the polarized single photons, no classical information is needed.
The intrinsic efficiency and total efficiency are both 1 in this
scheme as almost all of the instances are useful and each EPR pair
can be used to carry two bits of information. 相似文献
996.
应用计及浮力对湍动能及其耗散率的影响的k-epsilon湍流模式,结合有限分析法对密度差引起的平面铅垂紊动壁羽流进行了数值分析.在均匀环境条件下控制该类流动的连续性方程、流动方向的动量方程、浓度扩散方程、湍动能及其耗散率方程存在相似解.考虑到浮力通量守恒条件,应用有限分析法给出了铅直壁羽流的速度、相对密度差、湍动能及耗散率的分布,进而给出了各物理量最大值沿主流方向变化的关系式.湍流Schmidt数为1.0时的计算结果与实验资料吻合较好,表明应用有限分析法分析铅垂平面羽流是有效的,即在分析壁羽流时浮力对湍动能及其耗散率的影响应该予以考虑. 相似文献
997.
Nanoparticle coagulation in a planar jet via moment method 总被引:3,自引:1,他引:2
Large eddy simulations of nanoparticle coagulation in an incompressible pla- nar jet were performed.The particle is described using a moment method to approximate the particle general dynamics equations.The time-averaged results based on 3000 time steps for every case were obtained to explore the influence of the Schmidt number and the Damkohler number on the nanoparticle dynamics.The results show that the changes of Schmidt number have the influence on the number concentration of nanoparticles only when the particle diameter is less than 1 nm for the fixed gas parameters.The number concentration of particles for small particles decreases more rapidly along the flow di- rection,and the nanoparticles with larger Schmidt number have a narrower distribution along the transverse direction.The smaller nanoparticles coagulate and disperse easily, grow rapidly hence show a stronger polydispersity.The smaller coagulation time scale can enhance the particle collision and coagulation.Frequented collision and coagulation bring a great increase in particle size.The larger the Damkohler number is,the higher the particle polydispersity is. 相似文献
998.
农村地区由于地域和交通问题,给教师开展教研活动带来许多困难,信息技术催生的网络远程教研方式解决了地域和交通问题。如何有效开展网络远程教研活动,结合传统教研活动的特点,对网络远程教研方式进行了研究和探索。 相似文献
999.
CHENG Qing-Hua CAO Li XU Da Hai WU Da-Jin 《理论物理通讯》2005,44(5):867-872
Using the linear approximation method, we have studied how the correlation function C(t) of the laser intensity changes with time in the loss-noise model of the single-mode laser driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts. We have found that when the pump noise self-correlation time T changes, (i) in the case of r 〈〈 1, the C(t) vs. t curve experiences a changing process from the monotonous descending to monotonous rise, and finally to the appearance of a maximum; (ii) in the case of r 〉〉 1, the curve only exhibits periodically surging with descending envelope. When r 〈〈 i and T does not change, with the increase of the pump noise intensity P, the curve experiences a repeated changing process, that is, from the monotonous descending to the appearance of a maximum, then to monotonous rise, and finally to the appearance of a maximum again. With the increase of the quantum noise intensity O,, the curve experiences a changing process from the monotonous rise to the appearance of a maximum, and finally to the monotonous descending. The increase of the quantum noise with cross-correlation between the real and imaginary parts will lead to the fall of the whole curve, but not affect the form of the time evolution of C(t). 相似文献
1000.
HL-2A偏滤器运行模式的探针测量 总被引:1,自引:1,他引:0
在HL-2A装置的偏滤器位形运行模式下,用偏滤器靶板上的平面型嵌入式静电探针阵列测量了同一环截面的内外和上下四个中性化板上的电子温度、密度、悬浮电位分布。偏滤器运行模式下的边缘电子温度高于孔栏运行模式下的边缘的电子温度。比较了内外靶板之间的温度不对称性。给出了由18个米尔诺夫线圈信号重建获得的磁分界面,并用强磁场快速电离规测量了偏滤器室的中性气体压强变化。测量结果表明,在偏滤器运行模式下,主真空室中边缘粒子再循环降低,杂质通量水平下降。 相似文献