检索结果-南通市图书馆

Remarks on Definitions of Perturbation in General Relativity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2009年第2期51卷 375-377页

作者： he ping Key Laboratory of Frontiers in Theoretical Physics Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100080 China

There are two kinds of definitions of perturbation of physical quantities in the framework of general relativity： one is direct, the other is geometrical. Correspondingly, there are two types of gauge transformation related with these two definitions. The passive approach is based on the property of general covariance, and the active one is through the action of Lie-derivative. Although under a proper coordinate choice, the two approaches seem to agree with each other, they are different in nature. The geometrical definition of relativistic perturbation and the active approach for gauge transformation are more rigorous in mathematics and less confusing in physical explanation. The direct definition, however, seems to be plagued with difficulties in physical meaning, and the passive approach is more awkward to use, especially for high-order gauge transformations.

关键词： general relativistic perturbation gauge transformation active and passive approach

Foreground removal of 21cm fluctuation with multifrequency fitting

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2009年第6期9卷 653-664页

作者： Li-ping he National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

The 21 centimeter （21 cm） line emission from neutral hydrogen in the intergalactic medium （IGM） at high redshifts is strongly contaminated by foreground sources such as the diffuse Galactic synchrotron emission and free-free emission from the Galaxy, as well as emission from extragalactic radio sources, thus making its observation very complicated. However, the 21 cm signal can be recovered through its structure in frequency space, as the power spectrum of the foreground contamination is expected to be smooth over a wide band in frequency space while the 21 cm fluctuations vary significantly. We use a simple polynomial fitting to reconstruct the 21 cm signal around four frequencies 50, 100, 150 and 200 MHz with an especially small channel width of 20 kHz. Our calculations show that this multifrequency fitting approach can effectively recover the 21 cm signal in the frequency range 100 - 200 MHz. However, this method doesn＇t work well around 50 MHz because of the low intensity of the 21 cm signal at this frequency. We also show that the fluctuation of detector noise can be suppressed to a very low level by taking long integration times, which means that we can reach a sensitivity of ≈ 10 mK at 150 MHz with 40 antennas in 120 hours of observations.

关键词： cosmology theory, observations, diffuse radiation -- methods data analysis

Coherent attacks on a practical quantum oblivious transfer protocol

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第10期27卷 202-207页

作者： Guang-ping he School of Physics Sun Yat-sen UniversityGuangzhou 510275China

In a recent quantum oblivious transfer protocol proposed by Nagy et al., it was proven that attacks based on individual measurements and 2-qubit entanglement can all be defeated. Later we found that 5-body entanglement-based attacks can break the protocol. here we further tighten the security bound, by showing that the protocol is insecure against 4-body entanglement-based attacks, while being immune to 3-body entanglement-based attacks. Also, increasing the number of qubits in the protocol is useless for improving its security.

关键词： quantum cryptography quantum algorithm quantum oblivious transfer entanglement

The continuous wavelet derived by smoothing function and its application in cosmology

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2021年第9期73卷 95-104页

作者： Yun Wang ping he College of Physics Jilin UniversityChangchun 130012China Center for High Energy Physics Peking UniversityBeijing 100871China

The wavelet analysis technique is a powerful tool and is widely used in broad disciplines of engineering,technology,and *** this work,we present a novel scheme of constructing continuous wavelet functions,in which the wavelet functions are obtained by taking the first derivative of smoothing functions with respect to the scale *** to this wavelet constructing scheme,the inverse transforms are only one-dimensional integrations with respect to the scale parameter,and hence the continuous wavelet transforms(CWTs)constructed in this way are more ready to use than the usual *** then apply the Gaussian-derived wavelet constructed by our scheme to computations of the density power spectrum for dark matter,the velocity power spectrum and the kinetic energy spectrum for baryonic *** computations exhibit the convenience and strength of the *** transforms are very easy to perform,and we believe that the simplicity of our wavelet scheme will make CWTs very useful in practice.

关键词： wavelet analysis intergalactic medium large-scale structure of Universe

Evaluation of Transient Absorption Spectra of N, N, N, N- Tetra - ( p -methylphenyl ) - 4, 4- diamino - 1, 1- diphenyl Ether ( TPDAE ) for Electron Transfer from TPDAE to Fullerenes ( C_(60) / C_(70) ) by Laser Flash Photolysis

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2002年第12期13卷 1231-1234页

作者： he ping ZENG Department of Chemistry South China Normal UniversityGuangzhou 510631

Photoinduced electron transfer processes between fullerenes (C60 / C70) and N, N, N, N tetra - ( p-methylphenyl ) - 4, 4 diamino - 1, 1- diphenyl ether ( TPDAE ) have been studied by nanosecond laser flash photolysis. Quantum yields and rate constants of electron transfer from TPDAE to excited triplet state of fullerenes (C60 / C70 ) in benzonitrile have been evaluated by observing the transient absorption bands in the near-IR region where the excited triplet state, radical anion of fullerenes ( C60 / C70 ) and radical cations of TPDAE appear.

关键词： Photoinduced electron transfer fullerenes ( C_(60) / C_(70) ) transient absorption bands.

Prediction of liquid circulation flow rate in RH degasser:improvement of decarburization at low atmospheric pressure

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第7期31卷 1661-1667页

作者： Gu-jun Chen Sheng-ping he College of Materials Science and Engineering Yangtze Normal UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-heraeus(RH)*** predicted circulation flow rate was compared with that measured from a water model experiment to validate the mathematical ***,influence of snorkel immersion depth on liquid circulation flow rate was numerically investigated under an atmospheric pressure of 101 and 84 kPa,*** result indicates that the circulation flow rate of the RH degasser in the high-altitude area was severely reduced because of the decrease in atmospheric ***,increasing the snorkel immersion depth from 0.5 to 0.7 m can compensate for the decrease in atmospheric *** test result indicates that decarburization rate is significantly enhanced by increasing the snorkel immersion *** optimization,the percentage of heats with a final carbon content less than 0.002 wt.%is significantly increased from 22.0%to 96.4%.

关键词： RH degasser Two-fluid model Population balance model-Circulation flow rate Decarburization Snorkel immersion depth

Stochastic Estimations of Fermion Matrix Determinants with Unbiased Subtractions

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 1998年第6期15卷 401-403页

作者： YING he-ping Zhejiang Institute of Modern Physics Zhejiang UniversityHangzhou 310027

The Padé-Z_(2) stochastic estimator is used to calculate the fermion matrix determinants and the determinant ratios with an unbiased variational *** results on an 8^(3)×12 lattice with Wilson action show that the determinant ratio with a relatively small number of Z_(2) noises(e.g.,400)can be estimated by using the unbiased subtractions.

关键词： determinant Fermi estimator

NEW PRODUCT DESIGN STRATEGIES WITH SUBSIDY POLICIES

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2012年第3期21卷 356-371页

作者： Xuemei ZHANG Xiaoyan XU ping he School of Management University of Science & Technology of China Hefei 230026 China School of Economics and Management Fuyang Teachers College Fuyang 236037 China

Industrial development can enrich people＇s lives, but it also causes environmental pollution, which is an area of significant concern among governments, consumers, and companies. Governments formulate some environmental policies, which motivate industry by providing greater incentives for green product development. Consumers are classified into two groups - ordinary and green market segments - according to their environmental awareness and attitudes. In this regard, companies need to reconsider their primary product design strategies. By investigating the interactions among customers＇ preferences, firms＇ product strategies, and government subsidy policies, this paper presents a theoretical model for new product design strategies. After detailed theoretical analysis of such strategies, we found that to motivate firms to choose environmentally friendly product design strategies, governments should inaugurate effective subsidy policies. After simultaneously considering environmental issues and firms＇ benefits, we designed a subsidy policy. With such a policy, firms can change their primary product design strategies and develop both green and ordinary products, thereby increasing the firms＇ profits and improving the total environmental quality.

关键词： Product design strategy subsidy policy green product total environmental quality

Volume of fluid simulation of single argon bubble dynamics in liquid steel under RH vacuum conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第4期31卷 828-837页

Single argon bubble dynamics in liquid steel under Ruhrstahl-heraeus(RH)vacuum conditions were simulated using the volume of fluid method,and the ideal gas law was used to consider bubble growth due to heat transfer and pressure *** simulation with a constant bubble density was also performed to validate the numerical method,and the predicted terminal bubble shape and velocity were found to agree with those presented in the Grace diagram and calculated by drag correlation,*** simulation results under RH conditions indicate that the terminal bubble shape and velocity cannot be *** primary bubble growth occurs within a rising distance of 0.3 m owing to heating by the high-temperature liquid steel;subsequently,the bubble continues to grow under equilibrium with the hydrostatic *** the initial diameter is 8-32 mm,the bubble diameter and rising velocity near the liquid surface are 80-200 mm and 0.5-0.8 m/s,*** bubble rises rectilinearly with an axisymmetric shape,and the shape evolution history includes an initial sphere,(dimpled)ellipsoid,and spherical cap with satellite bubbles.

关键词： Bubble dynamics Liquid steel Volume of fluid Bubble growth Bubble shape Rising velocity