The geometric phase of a two-level atom in a narrow-bandwidth squeezed vacuum

In this paper, we derive the time dependent solution of the effective master equation for the reduced density matrix operator of a two level atom driven by a coherent laser field and damped by a finite bandwidth squeezed vacuum. The results show that the initial state setting, detuning parameter and Rabi frequency play important roles in the evolution of the system dynamics and geometric phase. We present a useful way for controlling the geometric phase variation for the system under consideration.     

Correlation between charge decay and solvent effect for melt-blown polypropylene electret filter fabrics

Melt-blown polypropylene electret fabrics are widely used as air filter media. However, its filtration efficiency gradually decays in application process. This paper is to investigate the correlation between filtration efficiency decay and solvent effect. Experimental results show that filtration efficiency displays a regular decrease when polypropylene electret fabrics are exposed to solvents in the sequence of water, ethanol, isopropanol and acetone. The results can be correlated to solubility parameter difference between polypropylene and solvent according to the Flory–Huggins swelling theory. Smaller solubility parameter difference leads to greater decay of filtration efficiency owing to greater affinity between polypropylene and solvent.     

Asymmetric shock heating and the terrestrial magma ocean origin of the Moon

One of the difficulties of the current giant impact model for the origin of the Moon is to explain the marked similarity in the isotopic compositions and the substantial differences in the major element chemistry. Physics of shock heating is analyzed to show that the degree of heating is asymmetric between the impactor and the target, if the target (the proto-Earth) had a magma-ocean but the impactor did not. The magma ocean is heated much more than the solid impactor and the vapor-rich jets come mainly from the magma-ocean from which the Moon might have been formed. In this scenario, the similarity and differences in the composition between the Moon and Earth would be explained as a natural consequence of a collision in the later stage of planetary formation. Including the asymmetry in shock heating is the first step toward explaining the chemical composition of the Moon.     

基于CPLD高精度恒流源技术的呼吸体积描记系统的设计

利用呼吸感应体积描记(RIP)技术测量呼吸参数已得到了越来越广泛的认可,针对人体呼吸运动引起传感线圈的电感量变化非常小(小于几百nH),一般系统难以保证精确性和适用性问题;硬件设计采用了高精度恒流源,锁相放大和自动增益控制放大电路,并详细分析了各部分电路的特性,包括在平静呼吸和用力呼吸模式下分别对14位测试者测量潮气量和呼吸频率,并且与德国耶格公司的肺功能仪所测量的结果对比;实验证明RIP系统在这两种模式下测量潮气量和呼吸频率等呼吸参数与速度描记仪存在显著的正相关关系,说明该系统工作良好、测量精确,操作简单、便于携带和低功耗,未来可以在临床上推广应用于长时间动态的呼吸监测。     

增程式电动汽车动力总成参数匹配设计

增程式电动汽车作为一种新型节能环保型汽车,是传统内燃机汽车向纯电动汽车过渡的一种车型;根据动力传动系统的设计原则和设计目标,基于铃木奥拓燃油汽车改装设计了增程式电动汽车的动力传动系统的参数匹配方法,根据电动汽车基本参数及其控制目标,对动力总成系统的关键零部件进行了匹配设计;匹配结果表明:电动机的额度电压为60 V,最高转速为4 000 r/min,额定功率为8 kW,额定转矩为40.43 N·m,峰值功率为11 kW,最大扭矩为80.86 N·m;增程器采用马勒增程器和两缸直列四冲程发动机;动力电池组采用磷酸铁锂子电池,单组额定容量为80 Ah、总电压为96 V;对于指导增程式电动汽车的开发、提高汽车性能和安全性,以及对于电动汽车底盘集成控制系统的开发都具有重要的工程应用意义。     

大模场掺镱双包层光子晶体光纤内包层新型结构研究

制备了掺镱多组分硅酸盐光子晶体光纤纤芯材料。其折射率为1.586,有效荧光半高宽为85.3 nm,荧光寿命为1.30 ms。分析了光纤结构参数对光子晶体光纤的归一化频率（单模截止条件）、数值孔径、有效模面积、非线性效应和限制损耗等参数的影响。设计了以该材料为纤芯,内包层为八边形、五层空气孔的新型结构光子晶体光纤。用有限元法对该光子晶体光纤性能进行了数值模拟。结果表明,该光纤有效模场面积为1 150 μm²;当空气孔直径为21.6 μm、孔间距为60 μm时,内包层数值孔径达到0.45。     

A frictional receding contact plane problem between a functionally graded layer and a homogeneous substrate

This paper investigates the plane problem of a frictional receding contact formed between an elastic functionally graded layer and a homogeneous half space, when they are pressed against each other. The graded layer is assumed to be an isotropic nonhomogeneous medium with an exponentially varying shear modulus and a constant Poisson’s ratio. A segment of the top surface of the graded layer is subject to both normal and tangential traction while rest of the surface is devoid of traction. The entire contact zone thus formed between the layer and the homogeneous medium can transmit both normal and tangential traction. It is assumed that the contact region is under sliding contact conditions with the Coulomb’s law used to relate the tangential traction to the normal component. Employing Fourier integral transforms and applying the necessary boundary conditions, the plane elasticity equations are reduced to a singular integral equation in which the unknowns are the contact pressure and the receding contact lengths. Ensuring mechanical equilibrium is an indispensable requirement warranted by the physics of the problem and therefore the global force and moment equilibrium conditions for the layer are supplemented to solve the problem. The Gauss–Chebyshev quadrature-collocation method is adopted to convert the singular integral equation to a set of overdetermined algebraic equations. This system is solved using a least squares method coupled with a novel iterative procedure to ensure that the force and moment equilibrium conditions are satisfied simultaneously. The main objective of this paper is to study the effect of friction coefficient and nonhomogeneity factor on the contact pressure distribution and the size of the contact region.     

Drag force on a moving heavy quark with deformed string configuration

To study drag force on a moving heavy quark through a plasma, we use a deformed AdS space-time, in which deformation parameter c describes non-conformality in AdS/QCD. In this case, the quark is mapped to a probe string in the AdS space. Considering the probable contribution of the deformation parameter in the probe string, we apply a general form of c-dependent string ansatz in the drag force computation. Then, we find the acceptable value of this parameter as it satisfies QCD calculations. Using this result, we also discuss the diffusion constant which is in agreement with the phenomenological result for the non-relativistic limit. Also, we show that while in absence of a deformation parameter, the probe string is a strictly increasing function of radial coordinate, the c-dependent probe string has a maximum value versus z.     

Predicting retention in reverse‐phase liquid chromatography at different mobile phase compositions and temperatures by using the solvation parameter model

The prediction capability of the solvation parameter model in reverse‐phase liquid chromatography at different methanol‐water mobile phase compositions and temperatures was investigated. By using a carefully selected set of solutes, the training set, linear relationships were established through regression equations between the logarithm of the solute retention factor, logk, and different solute parameters. The coefficients obtained in the regressions were used to create a general retention model able to predict retention in an octadecylsilica stationary phase at any temperature and methanol‐water composition. The validity of the model was evaluated by using a different set (the test set) of 30 solutes of very diverse chemical nature. Predictions of logk values were obtained at two different combinations of temperature and mobile phase composition by using two different procedures: (i) by calculating the coefficients through a mathematical linear relationship in which the mobile phase composition and temperature are involved; (ii) by using a general equation, obtained by considering the previous results, in which only the experimental values of temperature and mobile phase composition are required. Predicted logk values were critically compared with the experimental values. Excellent results were obtained considering the diversity of the test set.     

Intrinsic anisotropy of the effective acoustic properties in metafluids made of two-dimensional cylinder arrays

Within a unified theoretical framework, we extract the omnidirectional effective acoustic parameters for the metafluid consisting of isotropic fluid cylinders embedded in an isotropic fluid background. Besides the analytical formulas for the effective parameters reported previously, i.e., the bulk modulus and the mass density perpendicular to the cylinders, we also derive a simple expression for the effective mass density parallel to the cylinders. As expected, these two effective mass densities are not identical and constitute an anisotropic density tensor. Such intrinsic anisotropy can be engineered much stronger than the pure in-plane anisotropy induced by either anisotropic lattices or anisotropic scatterers.