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1.
Based on the potential flow theory, the vortex ring is introduced to simulate the toroidal bubble, and the boundary element
method is applied to simulate the evolution of the bubble. Elastic-plasticity of structure being taken into account, the interaction
between the bubble and the elastic-plastic structure is computed by combining the boundary element method (BEM) and the finite
element method (FEM), and a corresponding 3D computing program is developed. This program is used to simulate the three-dimensional
bubble dynamics in free field, near wall and near the elastic-plastic structure, and the numerical results are compared with
the existing experimental results. The error is within 10%. The effects of different boundaries upon the bubble dynamics are
presented by studying the bubble dynamics near different boundaries.
Supported by the National Natural Science Foundation of China (Grant No. 50779007), the National Science Foundation for Young
Scientists of China (Grant No. 50809018), the Specialized Research Fund for the Doctoral Program of Higher Education of China
(Grant No. 20070217074), the Defense Advanced Research Program of Science and Technology of Ship Industry (Grant No. 07J1.1.6),
and Harbin Engineering University Foundation (Grant No. HEUFT07069) 相似文献
2.
By using quantum bang-bang control technique, we studied the suppression of amplitude damping, or energy dissipation, in a
three-level atom in various configurations. We have explicitly given the bang-bang control groups in three different configurations,
and the pulse sequences for these bang-bang control operations.
Supported by the National Natural Science Foundation of China (Grant No. 10547003), the Key Project of Chinese Ministry of
Education (Grant No. 306020) and Chifeng College Scientific Research Fund (Grant No. ZRZD200604) 相似文献
3.
An efficient quantum secure direct communication protocol is presented over the amplitude damping channel. The protocol encodes
logical bits in two-qubit noiseless states, and so it can function over a quantum channel subjected to collective amplitude
damping. The feature of this protocol is that the sender encodes the secret directly on the quantum states, the receiver decodes
the secret by performing determinate measurements, and there is no basis mismatch. The transmission’s safety is ensured by
the nonorthogonality of the noiseless states traveling forward and backward on the quantum channel. Moreover, we construct
the efficient quantum circuits to implement channel encoding and information encoding by means of primitive operations in
quantum computation.
Supported by the National Natural Science Foundation of China (Grant Nos. 60873191 and 60821001), the Specialized Research
Fund for the Doctoral Program of Higher Education (Grant No. 200800131016), the Natural Science Foundation of Beijing (Grant
No. 4072020), the National Laboratory for Modern Communications Science Foundation of China (Grant No. 9140C1101010601), and
the ISN Open Foundation 相似文献
4.
Hausdorff Measure of the Singular Set of Landau-Lifshitz Equations with a Nonlocal Term 总被引:2,自引:0,他引:2
This paper is concerned with the partial regularity of the stationary solutions to the Landau-Lifshitz system of ferromagnetic spin chain with Gilbert damping and a nonlocal term in 3-dimensions. The Hausdorff measure of the singular set is discussed.The author is partially supported by the National Natural Science Foundation of China (Grant No.19971030) and by Guangdong Provincial Natural Science Foundation (Grant No.000671 and No.031495). 相似文献
5.
As is distinct from general gas-liquid two-phase flow, a large number of bubbles with different diameters belong to ship wakes.
Feasibility of Laplace equation, used to calculate wake sound speed (WSS), is confirmed based on differential postulation.
Defect for calculating the adiabatic sound speed of gases in references is showed, and a concept of WSS is proposed clearly.
A minimum WSS of 24.5 m/s is got when bubble ratio reads 0.5 according to the calculation when bubble dimension is less than
that of resonance. Also a weak dependence of WSS on pressures is predicted. WSS from calculation corresponds with the experimental
data of references well in high frequency domain, when the actual scale of bubbles is greater than the resonant scale.
Supported by the National Natural Science Foundation of China (Grant No.10274046) and Pre-study Fund of Military Equipment
(Grant No. 51448030101ZK1801) 相似文献
6.
We modify a uniform model of single bubble sonoluminescence, in which heat diffusion, water vapor diffusion and chemical reactions
are included to describe the bubble dynamics, and the processes of electron-atom bremsstrahlung, electron-ion bremsstrahlung
and recombination radiation, radiative attachment of electrons to atoms and molecules, line emissions of OH radicals and Na
atoms are taken into account to calculate the light emission. With this model, we compute the light pulse width, the photon
number per flash, the continuum and line spectra and the gas species as the products of chemical reactions, and try to compare
with all the experimental data available. We obtain good agreement with the observations of Ar and Xe bubbles in many cases,
but fail to match the experimental data of the photon number per flash. We also find that for He bubble the computed photon
number is always too small to interpret the observations.
Supported by the National Natural Science Foundation of China (Grant Nos. 10674081 and 10434070) 相似文献
7.
A recursive formulation is proposed for the method of reverberation-ray matrix (MRRM) to exactly analyze the free vibration
of a multi-span continuous rectangular Kirchhoff plate, which has two opposite simply-supported edges. In contrast to the
traditional MRRM, numerical stability is achieved by using the present new formulation for high-order frequencies or/and for
plates with large span-to-width ratios. The heavy computational cost of storage and memory are also cut down. An improved
recursive formulation is further proposed by modifying the iterative formula to reduce the matrix inversion operations. Numerical
examples are finally given to demonstrate the effectiveness and efficiency of the proposed recursive formulae.
Supported by the National Natural Science Foundation of China (Grant Nos. 10725210, 10832009, and 10432030), the National
Basic Research Program of China (Grant No. 2009CB623204), the Specialized Research Fund for the Doctoral Program of Higher
Education (Grant No. 20060335107), and the Program for New Century Excellent Talents in University (Grant No. NCET-05-0510) 相似文献
8.
Results from a space experiment on bubble thermocapillary migration conducted on board the Chinese 22nd recoverable satellite
were presented. Considering the temperature field in the cell was disturbed by the accumulated bubbles, the temperature gradient
was corrected firstly with the help of the temperature measurement data at six points and numerical simulation. Marangoni
number (Ma) of single bubble migrating in the space experiment ranged from 98.04 to 9288, exceeding that in the previous experiment
data. The experiment data including the track and the velocity of two bubble thermocapillary migration showed that a smaller
bubble would move slower as it was passed by a larger one, and the smaller one would even rest in a short time when the size
ratio was large enough.
Supported by the National Natural Science Foundation of China (Grant No. 10432060) and the Knowledge Innovation Program of
Chinese Academy of Sciences (KJCX2-SW-L05, KACX2-SW-322) 相似文献
9.
A nonlinear time dependent fluid simulation model is developed that describes the evolution of magnetohydrodynamic waves in the presence of collisional and charge exchange interactions of a partially ionized plasma. The partially ionized plasma consists of electrons, ions and a significant number of neutral atoms. In our model, the electrons and ions are described by a single fluid compressible magnetohydrodynamic (MHD) model and are coupled self-consistently to the neutral gas, described by the compressible hydrodynamic equations. Both the plasma and neutral fluids are treated with different energy equations that describe thermal energy exchange processes between them. Based on our self-consistent model, we find that propagating Alfvénic and fast/slow modes grow and damp alternately through a nonlinear modulation process. The modulation appears to be robust and survives strong damping by the neutral component. 相似文献
10.
Single-bubble sonoluminescence (SBSL) is achieved with strong stability in sulfuric acid solutions. Bubble dynamics and the
SBSL spectroscopy in the sulfuric acid solutions with different concentrations are studied with phase-locked integral stroboscopic
photography method and a spectrograph, respectively. The experimental results are compared with those in water. The SBSL in
sulfuric acid is brighter than that in water. One of the most important reasons for that is the larger viscosity of sulfuric
acid, which results in the larger ambient radius and thus the more contents of luminous material inside the bubble. However,
sonoluminescence bubble’s collapse in sulfuric acid is less violent than that in water, and the corresponding blackbody radiation
temperature of the SBSL in sulfuric acid is lower than that in water.
Supported by the National Natural Science Foundation of China (Grant Nos. 10434070 and 10704037) and the Ministry of Education
Priorities Project of China (Grant No. 103078) 相似文献
11.
A threshold quantum secret sharing (TQSS) scheme between multi-party and multi-party was proposed using a sequence of single
photons, which is useful and efficient when the parties of communication are not all present. We described the process of
this TQSS scheme and discussed its security. It was shown that entanglement is not necessary for quantum secret sharing. Moreover,
the theoretic efficiency was improved to approach 100% as almost all the instances can be used for generating the private
key, and each photon can carry one bit of information. This protocol is feasible with the present-day technique.
Supported by the National Basic Research Program of China (973 Program)(Grant No. 2007CB311100), the National High-Technology
Research and Development Program of China (Grant Nos. 2006AA01Z419 and 2006AA01Z440), the Major Research Plan of the National
Natural Science Foundation of China (Grant No. 90604023), the Scientific Research Common Program of Beijing Municipal Commission
of Education (Grant No. KM200810005004), the Scientific Research Foundation for the Youth of Beijing University of Technology
(Grant No. 97007016200701), the Doctoral Scientific Research Activation Foundation of Beijing University of Technology (Grant
No. 52007016200702), the ISN Open Foundation, and the National Laboratory for Modern Communications Science Foundation of
China (Grant No. 9140C1101010601) 相似文献
12.
Based on the three-phase theory proposed by Santos, acoustic wave propagation in a poroelastic medium saturated by two immiscible
fluids was simulated using a staggered high-order finite-difference algorithm with a time partition method, which is firstly
applied to such a three-phase medium. The partition method was used to solve the stiffness problem of the differential equations
in the three-phase theory. Considering the effects of capillary pressure, reference pressure and coupling drag of two fluids
in pores, three compressional waves and one shear wave predicted by Santos have been correctly simulated. Influences of the
parameters, porosity, permeability and gas saturation on the velocities and amplitude of three compressional waves were discussed
in detail. Also, a perfectly matched layer (PML) absorbing boundary condition was firstly implemented in the three-phase equations
with a staggered-grid high-order finite-difference. Comparisons between the proposed PML method and a commonly used damping
method were made to validate the efficiency of the proposed boundary absorption scheme. It was shown that the PML works more
efficiently than the damping method in this complex medium. Additionally, the three-phase theory is reduced to the Biot’s
theory when there is only one fluid left in the pores, which is shown in Appendix. This reduction makes clear that three-phase
equation systems are identical to the typical Biot’s equations if the fluid saturation for either of the two fluids in the
pores approaches to zero.
Supported by the Key Program of the National Natural Science Foundation of China (Grant No. 10534040) and the National Natural
Science Foundation of China (Grant No. 10674148) 相似文献
13.
The bending problem of a magnetic film-nonmagnetic substrate cantilever system is studied by using the principle of energy
minimization. Emphasis is placed on the analysis of geometrical and physical parameter dependence of the neutral plane, internal
film stress and strain of the cantilever system, and then the influence of such a parameter on the bending characteristic
is presented. The results indicate, owing to the anisotropic expanding feature of the magnetostriction, that the neutral plane
is generally anisotropic, and moves downwards rapidly with the increasing thickness ratio. Meanwhile, the bounding rigidity
of substrate on the film will decrease with the increasing thickness ratio, and thus release the film stress, i.e., it decreases,
but the film strain increases. The effect of Poisson’s ratio of the materials on the film strain, the stress and the neutral
plane in the direction transverse to the magnetization is prominent. For the strain and the stress in the magnetization, however,
the role of Poisson’s ratio is inconspicuous. This property is due to the initiative elongating (or contracting) feature of
the magnetic film along its magnetization.
Supported by the National Natural Science Foundation of China (Grant No. 10762001), the Key Project of the Chinese Ministry
of Education (Grant No. 206024), and the Program for New Century Excellent Talents in University of China (Grant No. NCET-2005-0272) 相似文献
14.
Kramers' model of diffusion over potential barriers, e.g., chemical reactions, based on the noise activated escape of a particle from a potential well, is considered. Kramers derived escape rates valid for intermediate and large damping, and in a separate analysis, for small damping. In the small damping limit, Kramers' intermediate result reduces to the transition state rate which does not agree with the small damping result. A new escape rate is derived that is uniformly valid for all values of the damping coefficient. The new rate reduces to Kramers' results in the appropriate limits and, in particular, connects Kramers' intermediate and small damping results.This work was partially supported by the Air Force Office of Scientific Research under Grant No. AFOSR-83-0086, U.S. Department of Energy under Grant No. DE-AC02-78ERO-4650, and the National Science Foundation under Grant No. MCS-83-00562. One of us (BJM) gratefully acknowledges the support of a John Simon Guggenheim Memorial Foundation Fellowship. 相似文献
15.
Leighton TG White RR Morfey CL Clarke JW Heald GJ Dumbrell HA Holland KR 《The Journal of the Acoustical Society of America》2002,112(4):1366-1376
The measurement of an acoustic emission, or scatter, from a bubble is not difficult. However, an accurate interpretation of that signal in terms of the bubble dynamics may require careful consideration. The study presented here is at first sight relatively simple: comparison of the predicted and measured quality factors of injected bubbles. While the measurement is normally done by monitoring the decay of passive emissions from a bubble, this technique becomes difficult with smaller bubbles. Therefore an active technique is introduced, which removes all the frequency-dependent effects on the measurement (such as transducer response) bar one. That, critically, is the effect of the change in the bubble resonance (frequency and damping) which results from the loading on the bubble due to the reverberant field. The vast majority of theoretical treatments of bubble acoustics assume free field conditions, yet the environmental conditions rarely if ever match these. Therefore measurements of bubble damping are compared both with the established free field theory, and with a new theory relevant to the prevailing reverberant conditions (whether caused by tank surfaces, monochromatic neighboring bubbles, or both). 相似文献
16.
The way to compare the efficiencies of different detect strategies (DSs) in the “ping-pong” protocol is studied. The trade-off
between information gain and disturbance is calculated and compared for different DSs. The comparison result primely tallies
with our intuitional analysis. It is shown that the analysis of this trade-off is a feasible way to compare the performances
of different DSs in theory.
Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA01Z419), the National
Natural Science Foundation of China (Grant Nos. 90604023 and 6087319), the National Laboratory for Modern Communications Science
Foundation of China (Grant No. 9140C1101010601), the Natural Science Foundation of Beijing (Grant No. 4072020), and the ISN
Open Foundation. 相似文献
17.
From the perspective of information theory and cryptography, the security of two quantum dialogue protocols and a bidirectional
quantum secure direct communication (QSDC) protocol was analyzed, and it was pointed out that the transmitted information
would be partly leaked out in them. That is, any eavesdropper can elicit some information about the secrets from the public
annunciations of the legal users. This phenomenon should have been strictly forbidden in a quantum secure communication. In
fact, this problem exists in quite a few recent proposals and, therefore, it deserves more research attention in the following
related study.
Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA01Z419), the National
Natural Science Foundation of China (Grant Nos. 90604023 and 60373059), the National Research Foundation for the Doctoral
Program of Higher Education of China (Grant No. 20040013007), the National Laboratory for Modern Communications Science Foundation
of China (Grant No. 9140C1101010601), the Natural Science Foundation of Beijing (Grant No. 4072020) and the ISN Open Foundation 相似文献
18.
Ambient noise data measured in an experiment conducted in shallow water near a sea-route were analyzed. It was observed that,
at low frequency, the horizontal correlation has an obvious difference from that predicted by the classical ambient noise
model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise
nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different
times verify that the proposed model can be used to forecast the ambient noise field in shallow water near the sea-route.
Supported by the National Natural Science Foundation of China (Grant No. 10734100), the Knowledge Innovation Program of the
Chinese Academy of Sciences (Grant No. KZCX1-YW-12-2), the National Basic Research Program of China (Grant No. 2007CB209603),
and the Open Foundation of China National Petroleum Corporation Key Laboratory (Grant No. GPKL0804) 相似文献
19.
Deceleration of a continuous-wave (CW) molecular beam with a single quasi-CW semi-Gaussian laser beam
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We propose a promising scheme to decelerate a CW molecular beam by using a red-detuned quasi-cw semi-Gaussian laser beam (SGB). We study the dynamical process of the deceleration for a CW deuterated ammonia (ND3) molecular beam by Monte-Carlo simulation method. Our study shows that we can obtain a ND3 molecular beam with a relative average kinetic energy loss of about 10% and a relative output molecular number of more than 90% by using a single quasi-cw SGB with a power of 1.5kW and a maximum optical well depth of 7.33mK. 相似文献
20.
The relationships between the morphological characteristics and the vulnerability of atherosclerotic plaque were analyzed
theoretically and several suggestions were proposed to evaluate the plaque vulnerability. Validated by animal experiments
and clinical studies, the theoretical results were confirmed.
Supported by the National Natural Science Foundation of China (Grant Nos. 10302016 and 60402023), the National Basic Research
Program of China (973 Program)(Grant No. 2006CB503803), and the National Hi-Tech Research and Development Program of China
(863 Program) (Grant No. 2007AA02Z448) 相似文献