Measurement of Concentration Fields near the Interface of a Rising Bubble by Holographic Interference Technique

holographic interference, concentration near the interface, bubble , mass transfer

Analyzing Bandwidth on the Microwave Absorber by the Interface Reflection Model

Metallic flaky sendust particles are prepared for use as fillers in electromagnetic attenuation composites. We report the interface reflection model to divide the broad bandwidth into electromagnetic loss and quarter-wavelength （λ/4） cancelation. Combining with the face reflection calculation, we identify the electromagnetic loss originated from skin effect, which is used to explain over half of the absorbed energy in high frequency band. Most impor- tantly, the unique electromagnetic loss cannot generate the reflection loss （RL） peak. Using the phase relation of face reflection, we show evidence that the λ/4 cancelation is vital to generate the RL peak. The calculated energy loss agrees well with the experimental data and lays the foundation for further research.

Contribution of Surface Defects to the Interface Conductivity of SrTiO_3/LaAlO_3

Based on the first-principles method, the structural stability and the contribution of point defects such as O, Sr or Ti vacancies on two-dimensional electron gas of n- and p-type LaAlO3/SrTiO3 interfaces are investigated. The results show that O vacancies at p-type interfaces have much lower formation energies, and Sr or Ti vacancies at n-type interfaces are more stable than the ones at p-type interfaces under O-rich conditions. The calculated densities of states indicate that O vacancies act as donors and give a significant compensation to hole carriers, resulting in insulating behavior at p-type interfaces. In contrast, Sr or Ti vacancies tend to trap electrons and behave as acceptors. Sr vacancies are the most stable defects at high oxygen partial pressures, and the Sr vacancies rather than Ti vacancies are responsible for the insulator-metal transition of n-type interface. The calculated results can be helpful to understand the tuned electronic properties of LaAlO3 /SrTiO3 heterointerfaces.

Research of Trap and Electron Density Distributions in the Interface of Polyimide/Al2O3 Nanocomposite Films Based on IDC and SAXS

The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS） tests. According to the electron density distribution for quasi two-phase mixture doped by spherical nanoparticles, the electron densities in the interfaces of PI/Al2O3 nanocomposite films are evaluated. The trap level density and carrier mobility in the interface are studied. The experimental results show that the distribution and the change rate of the electron density in the three layers of interface are different, indicating different trap distributions in the interface layers. There is a maximum trap level density in the second layer, where the maximum trap level density for the nanocomposite film doped by 25 wt% is 1.054 × 10^22 eV·m^-3 at 1.324eV, resulting in the carrier mobility reducing. In addition, both the thickness and the electron density of the nanocomposite film interface increase with the addition of the doped Al2O3 contents. Through the study on the trap level distribution in the interface, it is possible to further analyze the insulation mechanism and to improve the performance of nano-dielectric materials.

THE INTERFACE LAYERS AND CATHODOLUMINESCENCE STUDIES OF DIAMOND FILMS

Polycrystalline diamond films have been synthesized on various substrates by hot filament CVD from the mixture gases of methane and hydrogen. The interface layers between CVD diamond films and substrates have been investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In addition, visible luminescence between 2.0～3.5eV of undoped and boron-doped CVD diamond films has also been studied by cathodoluminescence.

Effect of Metallurgical Behaviour at the Interface between Ceramic and Interlayer on the Si_3N_4/1.25Cr-0.5Mo Steel Joint Strength

By using newly developed CuNi5~25Ti16~28 B rapldly solidifled brazing filler the joining of Si3 N4/1.25Cr-0.5Mo steel has been carried out with interlayer method. If employing the interlayer structure of steel (0.2 mm)/W (2.0 mm)/Ni(0.2 mm), the joint strength can be increased greatly compared with employing that of Ni/W/Ni, and the three point bend strength of the Joint shows the value of 261 MPa. The metallurgical behaviour at the interface between Si3N4 and the interlayer has been studied. It is found that Fe participated in the interfacial reactions between Si3N4 and the brazing filler at the Si3N4/steel (0.2 mm) interface and the compound Fe5Si3 was produced. However, since the reactions of Fe with the active Ti are weaker than those of Ni with Ti, the normal inter facial reactions were still assured at the interface of Si3N4/steel (0.2 mm) instead of Si3N4/Ni (0.2 mm), resulting in the improvement of the joint strength. The mechanism of the formation of Fe5Si3 is also discussed. Finally, some ideas to further ameliorate and simplify the interlayer structure are put forward.

Microstructure Model of the Interfacial Zone Between Fresh and Old Concrete

A new model of repaired concrete which divides the bonding interface into a penetrating layer,a strongly-affected layer and a weakly-affected layer was put forward.The model is mainly based on the observation of the microstructure of interface between fresh and old (3 months to 60 years) concretes by using scanning electron microscopy.Then,the mechanism of the microstructure formed was analyzed.Finally,the relationship between the micro-structure and macro-mechanical performance of the interface was discussed.

A novel interfacial thermodynamic model for predicting solubility of nanoparticles coated by stabilizers

To improve the stability of nanoparticles in aqueous solution,polymer or surfactant,etc.are often added in solutions during the preparation process of nanoparticles,which can induce new interfaces that influence the solubility of nanoparticles.In this work,a novel interfacial thermodynamic model for describing the Gibbs energy of the nanoparticles coated by stabilizers was proposed to predict the solubility of nanoparticles.Within the developed model,the activity coefficient of nano metal system was determined by Davies model and that of nano drug system by Perturbed-Chain Statistical Associating Fluid Theory(PC-SAFT).The Gibbs energy of the interface was established as a function of molecular parameters via the application for nano metal system.Furthermore,the model was further used to predict the solubility of nano drugs itraconazole,fenofibrate,and griseofulvin.It was found that the Gibbs energy of the interface plays an important role especially when the radius of nano metal is less than 40 nm,and the developed model can predict the solubility of nano drug with high accuracy in comparison with the experimental data as well as predict the changing trend of solubility of nano drugs that increases as the particle size decreases.Meanwhile,the stabilization mechanism of stabilizers on nano drugs was studied which provided theoretical guidance for the selection of polymer or surfactant stabilizer.These findings showed that the developed model can provide a reliable prediction of the solubility of nanoparticles and help to comprehend the stabilization mechanism of the stabilizers on nano drugs with different particle sizes,which is expected to provide important information for the design of nano drugs formulations.

FURTHER INVESTIGATION OF THE J_2-INTEGRAL IN BIMATERIAL SOLIDS

The J_2-integral induced from the interface of bimaterial solids(J_2^(interface))is stud- ied by numerical method.First,the effect on the J_2-integral induced from the interface is very significant in bimaterial solids,which is inherently related to that induced from the subinterface cracks.Moreover,it can be concluded that either the first or the second component of the J_k- vector is always equal to zero when the contour encloses both the cracks and the whole interface in bimaterial solids.Secondly,it can also be concluded that the interface does produce significant effect on the J_2-integral induced from the subinterface cracks(J_2^(sub))in bimaterial solids.This effect depends on the geometry of the crack arrangement,which is corresponding to the different interaction effect among the cracks and the interface.Moreover,the interface effect on the J_2^(sub) can be neglected when the distance from the crack center to the interface is large enough,which reveals that the bimaterial solids can be regarded as homogenous solids in fracture analysis when the subinterface crack is far enough from the interface.Three examples are given in this paper.

Numerical Analysis of Asphalt Pavements under Moving Wheel Loads

The responses of the pavement in service are the basis for the design of the semi-rigid base course asphalt pavement. Due to the dynamic characteristics of wheel loacis and the temperature loads, the dynamic response analysis is very significant. In this article, the dynamic analysis of asphalt pavement under moving wheel loads is carried out using finite dement method canpled with non-reflective boundary method. The influences of the base modulus, thickness, the vehicle velocity, the tire pressure, and the contact condition at the interface are studied using parametric analysis. The results of numerical analysis show that it is not appropriate to simply increase the base modulus or thickness in the design. It would be beneficial if the base design is optimized synthetically. The increase of damping is also beneficial to the pavements because of the surface deflection and the stresses declination. Furthermore, the good contact condition at the interface results in good performance because it combines every layer of the pavement to work together. As overload aggravates the working condition of the pavement, it is not allowed.

Applications of An Eddy-Viscosity Eliminator Based on Sigmoid Functions in Reynolds-Averaged Navier-Stokes Simulations of Sloshing Flow

Reynolds-averaged Navier-Stokes(RANS)turbulence modeling can lead to the excessive turbulence level around the interface in two-phase flow,which causes the unphysical motion of the interface in sloshing simulation.In order to avoid the unphysical motion of the interface,a novel eddy-viscosity eliminator based on sigmoid functions is designed to reduce the excessive turbulence level,and the eddy-viscosity eliminator based on polynomials is extracted from the cavitation simulations.Surface elevations by combining the eddy-viscosity eliminators and classical two-equation closure models are compared with the experiments,the ones by using the adaptive asymptotic model(AAM)and the ones by using the modified two-equation closure models.The root-mean-squared error(RMSE)is introduced to quantify the accuracies of surface elevations and the forces.The relation between the turbulence level in the transition layer and RMSEs of surface elevations is studied.Besides,the parametric analysis of the eddy-viscosity eliminators is carried out.The studies suggest that(1)the excessive turbulence level in the transition layer around the interface has a significant influence on the accuracies of surface elevations and the forces;(2)the eddy-viscosity eliminators can effectively reduce the excessive turbulence level in the transition layer to avoid the unphysical motion of the interface;(3)the k-ωSST model combined with the eddy-viscosity eliminators is appropriate for predicting surface elevations and forces in RANS simulations of sloshing flow.

Accurate Determination for the Energy & Temperature Dependence of Electron Capture CrossSection of Si-SiO_2 Interface States Using a New Method

A new technique for accurate determination of the electron and hole capture cross-sections of interface states at the insulator-semiconductor interface has been developed through measuring the initial time variation in the carrier filling capacitance transient, and full consideration is given to the charge-potential feedback effect on carrier capture process. A simplified calculation of the effect is also given. The interface states have been investigated with this technique at the Si-SiO_2 interface in an n-type Si MOS diode. The results show that the electron capture cross-section strongly depends on both temperature and energy.

Meso-mechanical Interfacial Behavior of Elbow Steel Fiber Reinforced Concrete

The strain distributions near the interface when the elbow steel fiber is pulled out from the half-mould concrete matrix are directly measured using a combined method of single fiber pull-out test and digital image correlation. Meanwhile, the real-time processes of the bonding, debonding and sliding at the interface are observed. The micro-mechanism of the strain localization in the failure process of interface when debonding occurs and the strengthening mechanism at the imbedded fiber are discussed. The experimental results show that the meso-scale strain localization gives rise to the localization of shear damage near the fiber interface. This strain localization characterized by the debonding process near the interface occurs, develops and moves gradually at an apparently regular interval. At the elbow part of the imbedded fiber, the peak value of the shearing stress occurs. But the primary debonding does not occur at this place because the strength of the shear damage is increased at the local area of the elbow part in the concrete, displaying an apparent reinforced effect at the end of the fiber.

Studies on the liquid-liquid interfacial mass transfer process using holographic interferometry

This paper aims at the interfacial phenomena of liquid-liquid mass transfer and its characteristic.By using the real-time holographic technique,the concen-tration distributions on the aqueous side were obtained according to holographic diagrams of mass transfer of ethanol through the interface of oil and water at different initial concentrations.Furthermore,the concentrations near the interface and the mass transfer coefficients were attained.A correlation of concentration near the interface to the concentration of the solute in the oil side was proposed.An approach of interfacial energy with solute concentration was established,and the calculated results are at good agreement with the experimental data.It is indicated that the liquid-liquid mass transfer process is approximately in accordance with two-film theory,the interfacial performance may be changed by the addition of the solute,and the interface of liquid-liquid is non-equilibrium thermodynamically during the mass transfer process.

The Curious Case of a Robot Doctor： ＂Human,＂ Labor and Expert Systems

While Amazon Mechanical Turk project refreshes the long-term dream of artificial intelligence by incorporating human beings into the automation of information circuits, it also calls attention to the role of technical platforms in reorganizing the division and mode of labor under the current information capitalism. This essay examines this transformed labor regime by outlining the discourses and imaginaries of Artificial Intelligence （AI） in late 197os and 198os China when expert systems-an artificial intelligence system designed to provide expert consultation in the absence of human experts-first appeared. I argue that these discourses and imaginaries surrounding expert systems were tied to the anticipation of a coming information society, and to the fetish of expert knowledge, and a shift from Mao＇s class-based politics to a depoliticized realm of professionalism. Bringing together the material, technical development of AI, the intellectual discourse of Post-Mao 1980s, as well as the imaginary domain of science fiction, this essay rethinks the politics of the ＂human＂ in the social context of Post-Mao＇s era. Keywords expert systems, labor, the interface, professionalism, depoliticization