Ultrasonic Vibration Suspends Large Pendant Drops

A stationary substrate can suspend only small pendant drops even with excellent wetting ability because of gravity. We report the suspension of large pendant water drops by a copper substrate that vibrates ultrasonically with a frequency of 22 kHz. The mass of the largest pendant drop suspended by the vibrating substrate reaches 1.1 g, which is 9 times that by the same stationary substrate. The pendant drop deforms drasticaJly and quickly at both the beginning and the end of the vibration procedure. As the vibration power increases, the contact area between the drop and substrate expands and the drop height shrinks accordingly. Theoretical analysis indicates that the Bernoulli pressure induced by ultrasonic vibration may contribute strongly to enhancing the suspensibility of pendant drops.     

Capillary Forces between Submillimeter Spheres and Flat Surfaces at Constant Liquid Volumes

We investigate the capillary forces between submillimeter spheres and flat surfaces at constant liquid volumes theoretically and experimentally. An iterative method is used to estimate the capillary force with contact angles as the boundary conditions and the constant volume as a constraint. The theoretical analysis shows that the maximum capillary force between them decreases with the increase of the liquid bridge volume at small contact angles. The experimental results show that the force is smaller than the theoretical values at the initial separation distances. It is also observed that the force first increases and then decreases with an increasing separation distance in some cases. These phenomena of capillary forces hysteresis are explained according to the wetting hysteresis.     

Influence of the Nonlinearity of Loudspeakers on the Performance of Thermoacoustic Refrigerators Driven by Current and Voltage

The influence of the nonlinearity of electrodynamic loudspeakers on the performance of thermoacoustic refrigerators with the loudspeakers as acoustic sources is studied by nonlinear equivalent circuit models of electrodynamic loudspeakers driven by current and voltage. The simulated results demonstrate that there are different nonlinear effects between current-drive and voltage-drive refrigerators, and the differences are mainly induced by the motional electromotive force caused by the coil moving in the magnetic field. With voltage driving, the influence of the nonlinearity of the loudspeaker on the diaphragm displacement and acoustic output power is much smaller than that with current driving. Therefore, considering the nonlinearity of the loudspeakers, a proper driving method must be chosen according to the practical applications although little difference is found with the linear models.     

Effect of Rolling Massage on Particle Moving Behaviour in Blood Vessels

The rolling massage manipulation is a classic Chinese massage, which is expected to eliminate many diseases. Here the effect of the rolling massage on the particle moving property in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that the particle moving behaviour depends on the rolling velocity, the distance between particle position and rolling position. The average values, including particle translational velocity and angular velocity, increase as the rolling velocity increases almost linearly. The result is helpful to understand the mechanism of the massage and develop the rolling techniques.     

Nonlinear Flow Numerical Simulation of an Ultra-Low Permeability Reservoir

A nonlinear flow mathematical model is established and the grid equation is deduced. A nonlinear flow reservoir numerical simulation program is compiled. The permeability loss coefficient is used to describe the permeability loss. A pilot calculation is made on the basis of actual field data, which reflects the reservoir development characteristics. The numerical simulation program based on nonlinear flow can anticipate the dynamic characteristics of the ultra-low permeability reservoir exploitation more exactly.     

Electrical Studies on Pentacene Thin Film Transistors with Different Channel Widths

In order to conduct electrical studies on organic thin film transistors, top-contact devices are fabricated by growing polycrystalline films of freshly synthesized pentacene over Si/SiO2 substrates with two different channel widths under identical conditions. Reasonable field effect mobilities in order of 10^-2-10^-3 cm^2V^-1s^-1 are obtained in these devices. An elaborative electrical characterization of all the devices is undertaken to study the variance in output saturation current, field effect mobility, and leakage current with aging under ambient conditions. As compared to the devices with longer channel width, the devices with shorter channel width exhibit better electrical performance initially. However, the former devices sustain the moderate performance much longer than the latter ones.     

Investigation on Guided-Mode Characteristics of Hollow-Core Photonic Crystal Fibre at Near-Infrared Wavelengths

Guided-mode characteristics of hollow-core photonic crystal fibre （HC-PCF） are experimentally and theoretically investigated. The transmission spectrum in the range from 755 to 845nm is observed and the loss is measured to be 0.12dB/m at 800nm by cut-back method. Based on the full-vector beam propagation method and the full-vector plane-wave method, the characteristics of mode field over propagation distance 1 m are simulated, and the results show that the propagation efficiency can be above 80%. Compared with the fundamental guided mode well confined in air core within shorter propagation distance, the second-order guided mode leaks into the cladding region and gradually attenuates due to larger refractive index difference. The primary loss factors in HC-PCF and the corresponding solutions are elementarily discussed.     

Spin Transport in a Magnetic Superlattice with Broken Two-Fold Symmetry

We theoretically investigate the spin-dependent electron transport properties in a magnetic superlattice （MSL） with broken two-fold symmetry. An abnormal barrier in the MSL can break the two-fold symmetry of the system when it is not located at the two-fold symmetry center. A two-fold symmetry breaking factor is introduced to describe the two-fold symmetry breaking degree. Our numerical calculations show that the transmission, the conductance and the spin polarization are non-trivially dependent on the two-fold symmetry breaking factor. When the factor is large enough, the polarization almost approaches 100% in a proper Fermi energy range. However, for two mutually mirror-symmetric MSLs with the same factor, their polarizations may be either similar or distinct. These features provide some clues to the design and applications of MSL-based spin filters or spin-dependent tunneling electron devices.     

Symmetry Energy and Isovector Giant Dipole Resonance in Finite Nuclei

We study the relationship between the properties of the isovector giant dipole resonance of finite nuclei and the symmetry energy in the framework of the relativistic mean field theory with six different parameter sets of nonlinear effective Lagrangian. A strong linear correlation of excited energies of the dipole resonance in finite nuclei and symmetry energy at and below the saturation density is found. This linear correlation leads to the symmetry energy at the saturation density at the interval 33.0 MeV ≤ S（po） 〈37.0 MeV. The comparison to the present experimental data in the soft dipole mode of 132Sn constrains approximately the symmetry energy at p = 0,1 fm^-3 at the interval 21,2MeV- 22.5 MeV. It is proposed that a precise measurement of the soft dipole mode in neutron rich nuclei could set up an important constraint on the equation of state for asymmetric nuclear matter.     

Effect of Discharge Voltage on an Ion Sheath Formed at a Grid in a Multi-Dipole Discharge Plasma

It is experimentally demonstrated that a relatively strong ion-rich sheath formed at a fixed negative bias of the grid can be changed to a rather weak ion sheath （sheath potential weakly retards electrons） only by increasing the discharge voltage in the system. At sufficiently high negative grid bias, an increase of discharge voltage enhances the ion collection current at the grid. An explanation is put forward in support of this experimental observation. A slight density enhancement with a fall in plasma electron temperature is also observed with the increasing negative grid bias.     

Structural Investigation of Solid Methane at High Pressure

High pressure studies of solid methane are performed using both classical simulated annealing and first-principles methods. A series of simulated annealing and geometry optimization reveal a monoclinic P21/b structure with the unit cell containing four methane molecules. The phonon dispersion curves and vibrational density of states indicate that this structure is stable in the pressure range 10-90 GPa. The electronic band structure and density of states show that this structure has not metalized until 90 GPa.     

Modification of Band Gap of -SiC by N-Doping

The geometrical and electronic structures of nitrogen-doped β-SiC are investigated by employing the first principles of plane wave ultra-soft pseudo-potential technology based on density functional theory. The structures of SiC1-xNx （x = 0, 1/32, 1/16, 1/8, 1/4） with different doping concentrations are optimized. The results reveal that the band gap of β-SiC transforms from an indirect band gap to a direct band gap with band gap shrinkage after carbon atoms are replaced by nitrogen atoms. The Fermi level shifts from valence band top to conduction band by doping nitrogen in pure β-SiC, and the doped β-SiC becomes metallic. The degree of Fermi levels entering into the conduction band increases with the increment of doping concentration; however, the band gap becomes narrower. This is attributed to defects with negative electricity occurring in surrounding silicon atoms. With the increase of doping concentration, more residual electrons, more easily captured by the 3p orbit in the silicon atom, will be provided by nitrogen atoms to form more defects with negative electricity.     

Effect of Coma Aberration on Orbital Angular Momentum Spectrum of Vortex Beams

Spiral spectra of vortex beams with coma aberration are studied. It is shown that the orbital angular momentum （OAM） states of vortex beams with coma aberration are different from those aberration-free vortex beams. Spiral spectra of beams with coma aberration are spreading. It is found that in the presence of coma aberration, the vortex beams contain not only the original OAM component but also other components. A larger coma aberration coefficient and/or a larger beam waist will lead to a wider spreading of the spiral spectrum. The results may have potential applications in information encoding and transmittance.     

Continuous-Variable Quantum Teleportation of Entangled Coherent States

We propose a quantum teleportation scheme for tripartite entangled coherent state （ECS） with continuous variable. Our scheme is feasible and economical in the sense that we need only linear optical devices such as beam splitters, phase shifters and photon detectors and employ three bipartite maximally ECSs as quantum channels. We also generalize the tripartite scheme into multipartite ease and calculate the minimum average fidelity for the schemes in tripartite and multipartite cases.     

First-Principles Study of Li Doping in a Double-Wall Carbon Nanotube

By performing first-principles calculations, we study Li doping in a double-wall carbon nanotube where a （5,0） tube is confined inside a （14,0） tube. There are three possible sites for Li doping and two of them are energetically favorable. The change of energy band structure is closely related to the doping sites and the charge transfer is investigated. Bader charge analysis indicates that Li prefers to donate its electron to the inner （5,0） tube. Moreover, the Li capacity of the system can reach LIC4.75 which makes it a promising candidate for Li-ion battery materials.     

A Novel Filter Scheme of Data Processing for SQUID-Based Magnetocardiogram

We present a new filter scheme for magnetocardiogram （MCG） signal processing based on the quasi-periodic characteristic of the signals. The key points of this scheme are to determine the exact numbers of data points in each cardiac cycle by using electrocardiogram （ECG） data acquired simultaneously with the MCG signal and to normalize the MCG data sequence in each cycle into an identical length. Compared with conventional filters, the scheme has the advantage of more powerful noise suppression with less signal distortion. The desire for having high quality output signals from raw MCG data acquired in a simple shielded room or even in unshielded environment may be realized with the scheme.     

New Periodic Solution to Jacobi Elliptic Functions of a (2+1)-Dimensional BKP Equation and a Generalized Klein-Gordon Equation

With the help of the homogeneous balance method, the Jacobi elliptic expansion method and the auxiliary equation method, the first elliptic function equation is used to obtain the Jacobi doubly periodic wave solutions of the (2+1)-dimensional B-type Kadomtsev-Petviashvili (BKP) equation and the generalized Klein-Gordon equation. The method is also valid for other (1+1)-dimensional and higher dimensional systems.     

Hybrid Deconvolution of Adaptive Optics Retinal Images from Wavefront Sensing

Adaptive optics can be used to compensate for the wave aberration of the human eyes to achieve high-resolution imaging in real time. However the correction ＆ partial due to the limitation of hardware. We propose a kind of hybrid image post-processing method, which uses the blind deconvolution combined with the residual data in wavefront sensor to restore the partially adaptive optics corrected retinal image. This method is applied in the image restoration of the vivid human retinal images. The results show that it is effective to improve the retinal image quality.     

Diagnosis of Multiple Gases Separated from Transformer Oil Using Cavity-Enhanced Raman Spectroscopy

The Raman signal of gas molecules is very weak due to its small scattering cross section. Here, a near-confocal cavity-enhanced Raman detection system is demonstrated. In the cavity, a high power light of 9W is achieved by using a cw 200mW 532nm laser, which greatly enhances the detection sensitivity of gas species. A photomultiplier tube connected to a spectrometer is used as the detection system. The Raman spectra of the mixed gases separated from transformer oil has been observed. The relationship of absolute Raman intensity and gas pressure is also obtained. To our knowledge, this is the first Raman system to detect the gases separated from transformer oil.