Numerical simulation of acoustic wake effect in acoustic agglomeration under Oseen flow condition

We numerically simulate the hydrodynamic interaction of aerosol particles due to the acoustic wake effect under the Oseen flow condition.Attraction is found for two nearby particles with an orientation angle of 0 to 50° with respect to the acoustic field,and weak repulsion is found outside this range.Good agreement is obtained between the numerical results and experiments in the literature.We study the influence of particle size,sound wave frequency and the particle separation.The result shows that the acoustic wake effect plays a significant role in acoustic agglomeration.It could be either the major agglomeration mechanism of monodisperse aerosols or the major refill mechanism for polydisperse aerosols to supplement orthokinetic interaction.     

Thermal detection of surface plasmons on gold nanohole arrays

We used a thin-film thermocouple to detect the thermal effect of surface plasmons excited in Au nanohole array structures.We found that the thermal electromotive force of Au film with periodic nanohole structures is three times greater than that of a bare Au film for 785-nm laser excitation at a given power.This effect is caused by the resonant excitation of localized surface plas- mons in the nanoholes.In addition,we found that the thermal electromotive force(EMF)of the Au film with dumbbell-like na- nohole arrays depends strongly on the incident polarization.The thermal EMF is the greatest when the excitation light is polarized perpendicular to the long axis of the dumbbell.     

Phosphonylation and aging mechanisms of mipafox and butyrylcholinesterase: A theoretical study

Phosphonylation and aging processes between butyrylcholinesterase with mipafox have been studied at the B3LYP/6-311G(d,p) level of theory. The calculated results indicate that the phosphonylation process employs a two-step addition-elimination mechanism with the addition (the first step) as the rate-limiting step. Two different calculation models revealed that the catalytic triad of butyrylcholinesterase plays an important role in accelerating the reaction. This is the same mechanism as the phosphonylation reaction of acetylcholinesterase by sarin reported by Wang et al. However, the energy barrier of the rate-limiting step in the present reaction is higher than that in phosphonylation reaction of acetylcholinesterase by sarin. This indicates the differences in the phosphonylation activity of sarin and mipafox. The aging process occurs through a two-step addition-elimination mechanism similar to the phosphonylation process with the addition as the rate-limiting step. The solvent effects have been evaluated by using a CPCM model and the results show that the stationary structures and the negative charges around some important atoms involved in the two processes are not significantly different. However, the energy barrier of the phosphonylation process is remarkably decreased, revealing that this process is feasible in solution.     

Single atoms in the ring lattice for quantum information processing and quantum simulation

We have demonstrated preparing and rotating single neutral rubidium atoms in an optical ring lattice generated by a spatial light modulator, inserting two atoms into a single microscopic optical potential efficiently by dynamically reshaping the optical dipole trap, trapping single atoms in a blue detuned optical bottle beam trap, and confining single atoms into the Lamb-Dicke regime by combining red and blue detuned optical potentials. In combination with the manipulation of internal states of single atoms, the study is opening a way for research in the field of quantum information processing and quantum simulation. In this paper we review the past works and discuss the prospects.     

Estimation of urbanization bias in observed surface temperature change in China from 1980 to 2009 using satellite land-use data

Since the 1980s,China has undergone rapid urbanization.Meanwhile,the climate has been warming substantially.In this paper,the urbanization effect on observed temperatures from 1980 to 2009 in China is estimated,based on analysis of urban land use from satellite observation.Urban land-use expansion(U) during 1980-2005 is applied as an urbanization index.According to these U values,stations are divided into three categories:(C1) intense urbanization around the stations;(C2) moderate urbanization around the stations;and(C3) minimal urbanization around the stations.Most C1 stations are in municipalities or provincial capitals,while C2 stations tend to be in prefecture-level cities.C3 stations are mostly in counties.The urban heat island(UHI) effect can be estimated if the urban effect on C3 is negligible.The warming of C1 or C2 relative to that of C3 represents their urbanization effects,assuming that the same larger-scale natural warming has affected each category.For C1,the local urbanization effect is 0.258°C/10 a over 1980-2009,accounting for 41% of the total warming;the trend at C2 is 0.099°C/10 a,or 21%.For all China,the urbanization effect is 0.09°C/10a,accounting for 20% of the total national warming.Winter urban warming is greater than in summer.The assumption of negligible urbanization effect on C3 is debatable,and so the true urbanization effect may equal or slightly exceed estimates.Further,the U index may have some uncertainties,for it is only one of the urbanization indices.However,it provides a new and direct estimation of environmental change,in contrast to indirect indices.     

Optimization criteria for the performance of heat and mass transfer in indirect evaporative cooling systems

The wide application of evaporative cooling techniques in which the optimization criteria form the theoretical basis for improving evaporative cooling performance is essential for energy conservation and emission reduction.Based on exergy analysis and the entransy dissipation-based thermal resistance method,this contribution aims to investigate the effects of flow and area distributions in the optimization of the performance of indirect evaporative cooling systems.We first establish the relationships of exergy efficiency,entransy dissipation-based thermal resistance and cooling capacity of a typical indirect cooling system.Using the prescribed inlet parameters,the heat and mass transfer coefficients and the circulating water mass flow rate,we then numerically validate that when the cooling capacity reaches a maximum,the entransy dissipation-based thermal resistance falls to a minimum while the exergy efficiency is not at an extreme value.The result shows that the entransy dissipation-based thermal resistance,not the exergy efficiency,characterizes the heat transfer performance of an evaporative cooling system,which provides a more suitable method for evaluating and analyzing the indirect cooling system.     

近断层长周期地震动前向性效应对峰值影响研究

筛选了断层距不大于15km的具有前向性效应的长周期近断层地震记录,分类汇总建立了统计分析数据样本库,对长周期地震动的竖向分量和水平向分量峰值比进行了分析,研究了震级、脉冲周期、不同分量对峰值加速度比的影响。在此基础上,采用前期建立的回归分析模型,对长周期地震动竖向分量和水平向两分量的峰值加速度进行了回归分析,拟合给出了峰值参数与震级和断层距的衰减关系式,通过拟合曲线与数据样本的峰值实测值对比,说明拟合关系式在一定的范围内可以用于近断层长周期地震峰值的预测。     

Investigations of a nanostructured FeMnSi shape memory alloy produced via severe plastic deformation

Low-cost iron-based shape memory alloys (SMAs) show great potential for engineering applications. The developments of new processing techniques have recently enabled the production of nanocrystalline materials with improved properties. These developments have opened avenues for newer applications for SMAs. The influence of severe plastic deformation induced by the high-speed high-pressure torsion (HSHPT) process on the microstructural evolution of an Fe–Mn–Si–Cr alloy was investigated. Transmission electron microscopic analysis of the alloy revealed the existence of nanoscale grains with an abundance of stacking faults. The high density of dislocations characteristic of severe plastic deformation was not observed in this alloy. X-ray diffraction studies revealed the presence of ε-martensite with an HCP crystal structure and γ-phase with an FCC structure.     

SEEBECK EFFECT IN OXYGEN PROBE USED FOROXYGEN DETERMINATION IN LIQUID STEEL

Heat conduction in oxygen probe was analyzed by means of non-steady state method and measured using "double probe" arrangement. The results showed that during the response process the thermal emf was decreased exponentially with the time and in case of low oxygen level the Seebeck coefficient and thermal conductivity of solid electrolyte agreed well with those in literatures.     

Zn-Cu电池的Joule热电阻与Ohmic电阻的理论研究

当Zn－Cu伏打电池处于缓慢、均匀稳定放电状态时,Joule热电阻RJ不等于Ohmic电阻R.RJ涉及由电流I所带的离子,而R则涉及电解质内所有离子．