美国小妞 寻根北京

张密有着一双不输赵薇的大眼睛，笑起来特别特别像港剧《鉴证实录》中的“小糖菜”，黝黑的肌肤又给人充满活力和健康的印象。张密很爱国，乍听之下用这个词来形容一名模特很突兀，可若你知道她是一个离开父母孤身回中国奋斗的美籍华人，就明白为什么这样给她下定义了。

Full tensor gravity gradiometry data inversion:Performance analysis of parallel computing algorithms

We apply reweighted inversion focusing to full tensor gravity gradiometry data using message-passing interface （MPI） and compute unified device architecture （CUDA） parallel computing algorithms, and then combine MPI with CUDA to formulate a hybrid algorithm. Parallel computing performance metrics are introduced to analyze and compare the performance of the algorithms. We summarize the rules for the performance evaluation of parallel algorithms. We use model and real data from the Vinton salt dome to test the algorithms. We find good match between model efficiency and feasibility of parallel computing gravity gradiometry data. and real density data, and verify the high algorithms in the inversion of full tensor

Pomeron-Quark Coupling from Charge Conjugation Invariance

Based on the charge conjugation invariance and the vazuum property of the Pomeron, we point out that the commonly used vector vertex of the Pomeron coupling to quarkis incorrect since it contradicts with the Pomeron property. We also claim that the soft Pomeron could be a tensor glueball ξ（2230） with quantum numbers I^GJ^PC = 0^＋2^＋＋ and total decay width Гtot ≌ 100 MeV, which lies on the soft Pomeron trajectory αp = 1.08＋ 0.20t. Therefore, the coupling vertex of the soft Pomeron to quark should be tensorial which is invariant under the charge conjugation and can explaIn why the inadequate vector coupling, γ^μ, of the soft Pomeron to quark is successful in dealing with Pomeron physics.

3D numerical investigation of effects of density and surface tension on mixing time in bottom-blown gas-stirred ladles

In molten phase metallurgical processes,mixing via gas injection has a vital role in obtaining a homogeneous product.The efficiency of mixing depends on operational variables such as gas flow rate and slag height as well as physical properties of the molten phases.A numerical simulation is conducted to study the above parameters in the flow behavior of a bottom-blown bath.The molten metal and the slag are modeled by water and oil,respectively.The numerical results,particularly the mixing time,are validated against experimental data.The results show that mixing time increases as the slag height increases and decreases as the density of the slag material increases.The mixing time decreases with an increase in the density of the primary phase;however,it increases as the surface tension between air and water increases.A case with properties close to a real molten metal is also modeled.The performance of the system is influenced by the momentum rather than the dissipative forces.Thus,the effect of the density of the molten phase on the mixing process is more pronounced compared to the effect of the surface tension between the air and the molten phase.

Crack fluid identification of shale reservoir based on stress-dependent anisotropy

Shale reservoirs are typically very tight, and crack are only a small part of the reservoir. The directional arrangement of cracks leads to the anisotropic characteristics of shale, and the type of fluid filled in cracks affects the shale reservoir evaluation and late development. Many rock physics theories and methods typically use second-and fourthorder crack density tensors to characterize the elastic anisotropy induced by cracks as well as the normal-to-tangential crack compliance ratio to distinguish between dry and saturated cracks. This study def ines an anisotropic crack f luid indicator for vertical transversely isotropy(VTI) media with vertical symmetry axis which is the integration of the normal-to-tangential crack compliance ratio in three directions. A new dimensionless fourth-order tensor, including crack f luid type, azimuth distribution, and geometric shape, is constructed by substituting the normal and tangential compliance into the fourth-order crack density tensor, which can also be used to identify the type of crack fluid in the VTI media. Using the Callovo–Oxfordian shale experimental data, the variation of the elastic properties of dry and saturated shale samples with axial stress is analyzed. The results demonstrate that the anisotropic crack f luid indicator of water-bearing shale samples is less than that of the dry shale samples and that the dimensionless fourth-order tensor of water-bearing shale samples is nearly one order of magnitude greater than that of the dry shale samples. Therefore, the anisotropic crack f luid indicator and dimensionless fourth-order tensor can ref lect the crack f luid type in shale samples and can be used for shale reservoir prediction and f luid identif ication.

Expansion of Urban Space and Land Use Control in the Process of Urbanization: an Overview

Urban expansion brought by the rapid progress of urbanization has caused many problems in China. It is a significant issue to evaluate the extent of urban expansion and to make appropriate controls over the sprawl of urban areas. With a comparative study of international experiences, this article analyzed the mechanism and consequences of urban expansion, reviewed the typical planning and financial policies adopted by other countries for controlling urban sprawl, and discussed the suitable densities of urban areas. The analysis results suggested that Chinese cities have no better choice but compact urban forms. To achieve the goal of compact development, intensive use of public transportation and high proportion of collective houses should be encouraged, and 60–100 m2 per capita is recommended as the reasonable range of urban density in large cities.

The Reduced Planck＇s Constant, Mach＇s Principle, Cosmic Acceleration and the Black Hole Universe

Based on the Mach＇s principle and the characteristic mass of the present universe, Mo a c3/2GHo, it is noticed that, ＇rate of decrease in the laboratory fine structure ratio＇ is a measure of the cosmic rate of expansion. If the observed laboratory fine structure ratio is a constant, then, independent of the cosmic red shift and CMBR observations, it can be suggested that, at present there is no cosmic acceleration. Obtained value of the present Hubble constant is 70.75 Km/sec/Mpc. If it is true that, rate of decrease in temperature is a measure of cosmic rate of expansion, then from the observed cosmic isotropy it can also be suggested that, at present there is no cosmic acceleration. At present if the characteristic mass of the universe is, Mo = c3/2GHo and if the primordial universe is a natural setting for the creation of black holes and other non-perturbative gravitational entities, it is also possible to assume that throughout its journey, the whole universe is a primordial growing and light speed rotating black hole. At any time, if cot is the angular velocity, then cosmic radius is c/ω1 and cosmic mass is c3/2Gω1 Instead of the Planck mass, initial conditions can be addressed with the Coulomb mass = Mc = √/4xeoG At present, if ω1= H0 the cosmic black hole＇s volume density, observed matter density and the thermal energy density are in geometric series and the geometric ratio is 1 ＋ ln（M0 ＋Mc）.

Key Exchange Protocol Based on Tensor Decomposition Problem

The hardness of tensor decomposition problem has many achievements, but limited applications in cryptography, and the tensor decomposition problem has been considered to have the potential to resist quantum computing. In this paper, we firstly proposed a new variant of tensor decomposition problem, then two one-way functions are proposed based on the hard problem. Secondly we propose a key exchange protocol based on the one-way functions, then the security analysis, efficiency, recommended parameters and etc. are also given. The analyses show that our scheme has the following characteristics: easy to implement in software and hardware, security can be reduced to hard problems, and it has the potential to resist quantum computing.Besides the new key exchange can be as an alternative comparing with other classical key protocols.

A new entropic force scenario and holographic thermodynamics

We propose a new holographic program of gravity in which we introduce a surface stress tensor.Our proposal differs from Verlinde's in several aspects.First,we use an open or a closed screen.Second,the temperature is not necessary,but a surface energy density and pressure are introduced.The surface stress tensor is proportional to the extrinsic curvature.Third,the energy we use is Brown-York energy and the equipartition theorem is violated by a non-vanishing surface pressure.We discuss holographic thermodynamics of a gas of weak gravity and find a chemical potential,and then show that Verlinde's program does not lead to reasonable thermodynamics.The holographic entropy is similar to the Bekenstein entropy bound.

Plane Symmetric Solutions in f(R,T) Gravity

The main purpose of this paper is to investigate the exact solutions of plane symmetric spacetime in the context of f(R,T)gravity[Phys.Rev.D 84(2011)024020],where f(R,T)is an arbitrary function of Ricci scalar R and trace of the energy momentum tensor T.We explore the exact solutions for two different classes of f(R,T)models.The first class f(R,T)=R+2f(T)yields a solution which corresponds to Taub's metric while the second class f(R,T)=f_1(R)+f_2(T)provides two additional solutions which include the well known anti-deSitter spacetime.The energy densities and corresponding functions for f(R,T)models are evaluated in each case.

Efect of Tensor Force on the Halo Structure of ^(29)Ne and ^(31)Ne

The structure of Ne isotopes has been investigated by using deformed Skyrme-Hartree-Fock （SHF） method and BCS approximation. Especially the effect of tensor force on the halo structure of 29Ne and 31Ne is discussed. To this end, the tensor contributions are considered to the energy density function and the single particle potential in SHF theory. For comparison, four Skyrme interactions are used： SLy5 and SGII without tensor force, and SLy5＋T and SGII＋ T with tensor force. The results indicate that the inclusion of tensor force shows a more pronounced halo structure for 31Ne.