光力场中粒子运动轨迹的计算

在采用米氏散射理论严格计算微纳粒子所受光力的基础上,研究了基于欧拉-理查森算法计算粒子运动轨迹的问题.相比欧拉算法和欧拉-克罗默算法,欧拉-理查森算法精度更高且收敛速度更快,是非常适合描绘粒子运动轨迹的方法.纳米粒子在周期性保守光力场中的运动轨迹与物理分析完全吻合,验证了该方法的有效性和稳定性.给出的计算方法,可用于更高效地研究光学微操控中胶体粒子和生物大分子的囚禁、输运、分类,以及宏观粒子的冷却等.

光场力对烧蚀物时空分布的影响

对烧蚀物的时空分布进行了研究。烧蚀物离开靶材表面时的速率分布由蒸发机制决定 ,在激光作用时间内烧蚀物的传输行为由扩散机制和光场力机制共同决定 ,激光作用结束后烧蚀物的传输行为由扩散机制单独决定 ,并解释了烧蚀物的时空分布及烧蚀物趋光运动的现象。

纳秒激光与靶材相互作用过程分析

利用纳秒激光在薄铜片上进行多脉冲打孔时 ,出现一种反常现象 ,在 2个值处 ,随着单脉冲能量的提高 ,打 1个孔所需脉冲次数不但没有减少 ,反而增加 ,根据环境气体分解消耗激光能量解释了第 1处的反常现象 ,并首次提出了等离子体受光场力的作用 ,在激光作用初期 ,使靶表面形成一层致密的等离子体 ,阻挡了后续激光到达靶材 ,引起了第

Activating d^(10)electronic configuration to regulate p-band centers as efficient active sites for solar energy conversion into H_(2)by surface atomic arrangement

Relationship between the activity for photocatalytic H_(2)O overall splitting(HOS)and the electron occupancy on d orbits of the active component in photocatalysts shows volcanic diagram,and specially the d^(10)electronic configuration in valley bottom exhibits inert activity,which seriously fetters the development of catalytic materials with great potentials.Herein,In d^(10)electronic configuration of In_(2)O_(3)was activated by phosphorus atoms replacing its lattice oxygen to regulate the collocation of the ascended In 5p-band(Inɛ5p)and descended O 2p-band(Oɛ2p)centers as efficient active sites for chemisorption to*OH and*H during forward HOS,respectively,along with a declined In 4d-band center(Inɛ4d)to inhibit its backward reaction.A stable STH efficiency of 2.23%under AM 1.5 G irradiation at 65°C has been obtained over the activated d^(10)electronic configuration with a lowered activation energy for H_(2)evolution,verified by femtosecond transient absorption spectroscopy,in situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculations of dynamics.These findings devote to activating d^(10)electronic configuration for resolving the reaction energy barrier and dynamical bottleneck of forward HOS,which expands the exploration of high-efficiency catalytic materials.

Reflection spectra of fiber Bragg gratings in quadratic strain field

We theoretically analyze the reflection spectra of the fiber Bragg gratings in the quadratic strain field,and resolve the numerical value with transfer matrix method.When the value of pressure is changed,we can obtain diverse reflection spectra of the fiber Bragg gratings,which is in good accordance with the experimental results.

Channel-Resolved Ultrafast Dissociation Dynamics of NO2 Molecules Studied via Femtosecond Time-Resolved Ion Imaging

The ultrafast dissociation dynamics of NO2 molecules was investigated by femtosecond laser pump-probe mass spectra and ion images.The results show that the kinetic energy release of NO+ions has two components,0.05 eV and 0.25 eV,and the possible dissociation channels have been assigned.The channel resolved transient measurement of NO^+provides a method to disentangle the contribution of ultrafast dissociation pathways,and the transient curves of NO^+ions at different kinetic energy release are fitted by a biexponential function.The fast component with a decay time of 0.25 ps is generated from the evolution of Rydberg states.The slow component is generated from two competitive channels,one of the channel is absorbing one 400nm photon to the excited state A^2B2,which has a decay time of 30.0ps,and the other slow channel is absorbing three 400nm photons to valence type Rydberg states which have a decay time less than 7.2ps.The channel and time resolved experiment present the potential of sorting out the complex ultrafast dissociation dynamics of molecules.

Ab initio Study of Anharmonic Force Field and Spectroscopic Constants for Germanium Dichloride

Ab initio study of the equilibrium structure, spectroscopy constants, and anharmonic force field for several isotopomers of germanium dichloride （70GeCl2, 72GECl2, and 76GeCl2） have been carried out at the MP2 and CCSD（T） levels of theory using cc-pVTZ basis set. The cal- culated geometries, rotational constants, vibration-rotation interaction constants, harmonic frequencies, anharmonic constants, quartic and sextic centrifugal distortion constants, cubic and quartic force constants are compared with experimental data. For small mass differences of the Ge isotopes, the isotopic effects for germanium dichloride are much weaker. The agreements are satisfactory for these two methods, but the deviations of CCSD（T） results are slightly larger than that of MP2, because of CCSD（T）＇s inadequate treatment of electron correlation in hypervalent Cl atom.

Labor Market Aspects of the ＂New Rurality＂： Employment, Commuting and Entrepreneurship in Rural Sweden

Around two thirds of the Swedish rural areas experienced positive net migration during the period 2003-2005. This paper examines the development in the Swedish rural areas from the perspective of the ＂new rurality＂ or the new rural economic order with regard to migratory movements. The paper analyzes determinants of net migration to rural areas in general and to different types of regions, and the impacts of in-migration on rural labor markets, self-employment and other socio-economic conditions. The determinants of the migration pattern were mainly the size of adjacent local and regional centers, income and education levels that all had positive impacts, while commuting distance and unemployment rate had contrary effects. In comparison with the original inhabitants, the newcomers had lower incomes, a lower employment ratio and a lower degree of entrepreneurial activities, but higher education levels. These differences might be explained by the age differences between stayers （older） and in-migrants （younger）. This indicates that the two groups were in different stages of their life cycles. One central conclusion drawn from the paper is that the effect of in-migration on the composition of the rural population is about the same in rural areas all over Sweden.

The redshift and the blueshift of spectral lines and the motion of mass-points in gravitational fields of photon stars

The redshift and the blueshift of spectral lines in gravitational fields of photon stars are studied when the observing and emitting points of the spectral lines locate at different positions. And the motion of masspoints is also studied. The studies show that the redshift and the blueshift of spectral lines in gravitational fields of photon stars can he arbitrarily positive, and the motion of mass-points in gravitational fields of photon stars can be used to determine the mass of photon stars.

Quantum Entanglement Dynamics of Two Atoms in Quantum Light Sources

Quantum entanglement dynamics of two Tavis-Cummings atoms interacting with the quantum light sourcesin a cavity is investigated.The results show the phenomenon that the concurrence disappears abruptly in a finite time,which depends on the initial atomic states and the properties of squeezed states.We find that there are two decoherencefreestates in squeezed vacuum fields:one is the singlet state,and the other entangled state is the state that combinesboth excited states and ground states with a relative phase being equal to the phase of the squeezed state.

Potential of Photovoltaic Industry in Egypt

PV （photovoltaic） market is dominated by Europe, especially Germany and Spain. However, the PV industry leaders recently exist in Asia. The huge market growth require industry growth, but with competitive cost. The electricity shortage in Egypt makes transferring to photovoltaic technology necessary, especially with the high solar radiation. The only reason why grid parity is not yet reached in Egypt is the elevated subsidiary of conventional electricity. If this subsidy is transformed to incentives for using and manufacturing solar cells, the situation will vary. This article shows that transferring PV industry to Egypt has a potential of cost saving of 5.7%, which could be translated either into competitive price or higher return on investment. This work is not a feasibility study. However, based on the cost structure of each phase in the PV industry value chain, the benefit （5.7% cost reduction potential） of transferring the industry to Egypt is worthy to accomplish the needed feasibility study.

Surface Temperature Field of Ti-66Al and Ti-Al and Ti-4848Al AlloysAl Alloys Under Continuous Laser AblationUnder Continuous Laser Ablation

The high temperature fire retardancy of titanium alloy is an important factor restricting its application in aero-engine,and the laser ignition method can accurately reflect the fire retardancy of titanium alloy under local heating.Due to the limitations of laser ignition experiments on the microscopic boundary and the transient propagation mechanism of the temperature field,molecular dynamics(MD)simulations and JMatPro calculation were applied to study the temperature field of Ti-6Al and Ti-48Al alloys.The results show that a molten pool is formed on the surface of Ti-Al alloys under continuous laser irradiation,and the temperature field of the molten pool is normally distributed from the center to the edge.When the center temperature reaches the critical point of ignition,the extended combustion occurs,and the extended combustion path advances along the direction of the air flow.Compared with Ti-6Al alloy,Ti-48Al alloy has higher fire retardancy under laser ablation.This is due to the better heat transfer performance of Ti-48Al,which leads to the weakening of the heat concentration effect near the boundary of the spot temperature field.So it is necessary to increase the partial pressure of oxygen,and thus to reduce the ignition point of the alloy in order to achieve the ignition boundary condition of Ti-48Al alloy under the same laser heat source.In the aspect of extended combustion path,the boundary heat collection effect of specimens shown by MD models reveals another mechanism affecting combustion expansion path besides the direction of air flow.That is,the heat generated by the laser spot is interrupted when it is transmitted to the boundary of the specimen along the short side direction,resulting in a concentration of heat near the boundary.So the combustion path also tends to expand along this direction.

A triple-exposure color PIV technique for pressure reconstruction

The study developed a triple-exposure color particle image velocimetry(TE-CPIV) technique associated with pressure reconstruction, and validated its feasibility. A light source with the three primary colors of red, green, and blue(R, G, and B) is produced in a time sequence by a liquid crystal display(LCD) projector. Particle images at three different instants under the color illuminations are captured in one snapshot using a color digital single-lens reflex(SLR) camera with a complementary metal-oxide semiconductor(CMOS) sensor. A contamination correction algorithm based on a specific calibration is performed on the different color layers(R layer, G layer, and B layer) of the raw color image to reduce the contaminated intensity of each color illumination on the other two color layers. The corrected intensity generates three new color layers, from which a standard cross-correlation process in the classical PIV method is used to obtain two velocity fields. Eventually, an instantaneous pressure field is reconstructed from the two velocity fields. The feasibility of TE-CPIV was tested by two experiments with a solid body rotation flow and a cylinder wake flow. The results show acceptable accuracy and robustness of the new technique. The idea of the TE-CPIV is believed to provide a simple and effective way of estimating a pressure field with low cost and high convenience.

Exact transformation optics by using electrostatics

We present a novel method for designing transformation optical devices based on electrostatics.An arbi-trary transformation of electrostatic field can lead to a new refractive index distribution,where wave-fronts and energy flux lines correspond to equipotential surfaces and electrostatic flux lines,respectively.Owing to scalar wave propagating exactly following an eikonal equation,wave optics and geometric optics share the same solutions in the devices.The method is utilized to design multipole lenses derived from multipoles in electrostatics.The source and drain in optics are considered as corre-sponding to positive charge and negative charge in the static field.By defining winding numbers in vir-tual and physical spaces,we explain the reason for some multipole lenses with illusion effects.Besides,we introduce an equipotential absorber to replace the drain to correspond to a negative charge with a grounded conductor.Therefore,it is a very general platform to design intriguing devices based on the combination of electrostatics and transformation optics.