EXISTENCE OF POSITIVE PERIODIC SOLUTION TO A CLASS OF NEUTRAL DELAY COMPETITION MODEL

By means of the theory of coincidence degree, sufficient condition for the existence of positive periodic solution to certain neutral delay competition model is obtained.     

引力场中的质量亏损效应

利用Hellings-Nordtvedt理论,我们得到了一类荷磁天体(含宇宙常数)的引力场中质量亏损效应的表达式。通过讨论这些表达式中的参数，我们得到了在不同条件下的质量亏损表达式。这些结果对于天体形成过程中能量辐射机制的研究是有意义的。     

Flexibly Enhanced Photonic Spin Hall Effect via Selective Brewster Angle

The manipulating of photonic spin Hall effect (SHE) plays a crucial role for development of spin-dependent nanodevices and systems. Since the photonic SHE is generally enhanced near the Brewster angle, the choice of incident angle usually has low flexibility with natural materials due to their dielectric constants. Herein, an efficient method to flexibly enhance the photonic SHE by utilizing selective Brewster angle in an anisotropic metamaterial is proposed. Through adjusting the thickness ratio of two media in metamaterial, the Brewster angle can be flexibly adjusted in a broad range (nearly 0–90°). With the selective Brewster angle, the spin-dependent transverse shift can be enhanced at nearly arbitrary incident angles. Furthermore, based on this structure, a binary encoding system is demonstrated, realizing information conversion around incident angles. This research work provides more possibilities for applications in manipulating photonic SHE.     

Resonance Interaction Energy in κ-Minkowski Spacetime

If gravity is quantized, one of the consequences may be that the spacetime coordinates are quantized and become noncommutative. The κ-Minkowski spacetime is such kind of noncommutative spacetime. In this paper, the resonance interaction energy of a two-atom system coupled with a fluctuating vacuum scalar field in the κ-Minkowski spacetime is studied. It is found that the resonance interaction energy is dependent on the interatomic separation, the transition wavelength of the atoms, and the spacetime non-commutativity. When the interatomic separation is small compared with a characteristic length determined by the spacetime non-commutativity parameter and the transition wavelength, the resonance interaction energy is that in the Minkowski spacetime plus a correction due to the spacetime non-commutativity. When the interatomic separation is comparable to or larger than the characteristic length, the resonance interaction energy cannot be organized in the form of a Minkowski term plus a correction, which indicates that the long-range behavior of the vacuum in the κ-Minkowski spacetime is fundamentally different from that in the Minkowski spacetime.     

ELECTROELASTIC FIELD FOR AN IMPERMEABLE ANTI-PLANE SHEAR CRACK IN A PIEZOELECTRIC CERAMICS PLATE

ＩｎｔｒｏｄｕｃｔｉｏｎＤｕｅｔｏｔｈｅｉｎｔｒｉｎｓｉｃｃｏｕｐｌｉｎｇｃｈａｒａｃｔｅｒｉｓｔｉｃｓｂｅｔｗｅｅｎｅｌｅｃｔｒｉｃａｎｄｅｌａｓｔｉｃｂｅｈａｖｉｏｒｓ,ｔｈａｔｉｓ,ａｐｐｌｉｅｄｍｅｃｈａｎｉｃａｌｌｏａｄｉｎｇｐｒｏｄｕｃｅｓｅｌａｓｔｉｃｄｅｆｏｒｍａｔｉｏｎ ,ａｓｗｅｌｌａｓｅｌｅｃｔｒｉｃｆｉｅｌｄ ,ａｎｄｃｏｎｖｅｒｓｅｌｙｅｌｅｃｔｒｉｃｆｉｅｌｄｃａｎｇｉｖｅｒｉｓｅｔｏｅｌａｓｔｉｃｄｅｆｏｒｍａｔｉｏｎ ,ｐｉｅｚｏｅｌｅｃｔｒｉｃｍａｔｅｒｉａｌｓｈａｖｅ…     

An implicit-explicit upwind algorithm for the parabolized Navier-Stokes equations

In this paper, a second-order implicit-explicit upwind algorithm has been developed for three-dimensional Parabolized Navier-Stokes (PNS) equations. The agreement between the results of the new upwind algorithm and those of the implicit upwind algorithm and its ability in marching a long distance along the streamwise direction have been shown for the supersonic viscous flow past a sphere-cone body. The CPU time is greatly reduced. The project supported by the National Natural Science Foundation of China     

Highly efficient enzyme immobilization by nanocomposites of metal organic coordination polymers and carbon nanotubes for electrochemical biosensing

New nanocomposites with multi-walled carbon nanotubes (MWCNTs) embedded in metal-organic coordination polymers (MOCPs) were successfully prepared as highly efficient matrices of enzyme immobilization for sensitive electrochemical biosensing. NaAuCl₄ was pre-adsorbed on the MWCNTs to act as anchor sites to further coordinate with ligand benzenedithiol and form MOCPs. The formation of MWCNTs-MOCPs one-pot entrapped glucose oxidase (GOx) with a ratio close to 100% and exhibited enhanced mass-transfer over MOCPs. Thus MWCNTs-MOCPs-modified electrodes present superior enzymatic catalysis performance of greatly enhanced sensitivity (136 μA cm^− 2 mM^− 1) and magnitudes-lower detection limit (48 nM), being superior to most analogues.     

Griffith crack moving in a piezoelectric strip

Summary  The dynamic problem of an impermeable crack of constant length 2a propagating along a piezoelectric ceramic strip is considered under the action of uniform anti-plane shear stress and uniform electric field. The integral transform technique is employed to reduce the mixed-boundary-value problem to a singular integral equation. For the case of a crack moving in the mid-plane, explicit analytic expressions for the electroelastic field and the field intensity factors are obtained, while for an eccentric crack moving along a piezoelectric strip, numerical results are determined via the Lobatto–Chebyshev collocation method for solving a resulting singular integral equation. The results reveal that the electric-displacement intensity factor is independent of the crack velocity, while other field intensity factors depend on the crack velocity when referred to the moving coordinate system. If the crack velocity vanishes, the present results reduce to those for a stationary crack in a piezoelectric strip. In contrast to the results for a stationary crack, applied stress gives rise to a singular electric field and applied electric field results in a singular stress for a moving crack in a piezoelectric strip. Received 14 August 2001; accepted for publication 24 September 2002 The author is indebted to the AAM Reviewers for their helpful suggestions for improving this paper. The work was supported by the National Natural Science Foundation of China under Grant 70272043.     

On lengths,areas and Lipschitz continuity of polyharmonic mappings

In this paper, we continue our investigation of polyharmonic mappings in the complex plane. First, we establish two Landau type theorems. We also show a three circles type theorem and an area version of the Schwarz lemma. Finally, we study Lipschitz continuity of polyharmonic mappings with respect to the distance ratio metric.