Temperature and current sensitivity extraction of optical superconducting transition-edge sensors based on a two-fluid model

Optical superconducting transition-edge sensor(TES)has been widely used in quantum information,biological imaging,and fluorescence microscopy owing to its high quantum efficiency,low dark count,and photon number resolving capability.The temperature sensitivity(α_(I))and current sensitivity(β_(I))are important parameters for optical TESs,which are generally extracted from the complex impedance.Here we present a method to extractα_(I)andβ_(I)based on a two-fluid model and compare the calculated current-voltage curves,pulse response,and theoretical energy resolution with the measured ones.This method shows qualitative agreement that is suitable for further optimization of optical TESs.

High-order targeted essentially non-oscillatory scheme for two-fluid plasma model

The weakly ionized plasma flows in aerospace are commonly simulated by the single-fluid model,which cannot describe certain nonequilibrium phenomena by finite collisions of particles,decreasing the fidelity of the solution.Based on an alternative formulation of the targeted essentially non-oscillatory(TENO)scheme,a novel high-order numerical scheme is proposed to simulate the two-fluid plasmas problems.The numerical flux is constructed by the TENO interpolation of the solution and its derivatives,instead of being reconstructed from the physical flux.The present scheme is used to solve the two sets of Euler equations coupled with Maxwell's equations.The numerical methods are verified by several classical plasma problems.The results show that compared with the original TENO scheme,the present scheme can suppress the non-physical oscillations and reduce the numerical dissipation.

Effect of Solving Models on Euler Vectors

In the process of solving Euler vectors based on GNSS horizontal movement field,the number of estimated parameters can affect Euler vector results. This issue is analyzed through theoretical deduction and practical example in this paper. Firstly,the difference between the results of Euler vectors in different solving models is deduced. Meanwhile, based on GNSS horizontal movement field in the Chinese mainland from 2004 to 2007,two common models( RRM and REHSM) are used to discuss the impact of solving models on Euler vectors and the follow-up study. The result shows that the maximum value of the difference in a block's entire rotation can reach 2. 6mm /a,and should not be ignored. Therefore,the results of horizontal movement are different using different kinematic block models,and this should be paid more attention in the analysis of crustal horizontal movement.

Euler Characteristic Scheme of Globally Searching for Flaws in Surface Modeling

This paper presents a new scheme of flaw searching in surface modeling based on Euler Characteristic. This scheme can be applied to surface construction or reconstruction in computer. It is referred to as Euler Accompanying Test (EAT) algorithm in this paper. Two propositions in algebraic topology are presented, which are the foundation of the EAT algorithm. As the modeling is the first step for rendering in the animation and visualization, or computer-aided design (CAD) in related applications, the flaws can bring some serious problems in the final image or product, such as an artificial sense in animation rendering or a mistaken product in industry. To verify the EAT progressive procedure, a three-dimensional (3D) stamp model is constructed. The modeling process is accompanied by the EAT procedure. The EAT scheme is verified as the flaws in the stamp model are found and modified.

GPR Wave Propagation Model in a Complex Geoelectric Structure Using Conformal First-Order Symplectic Euler Algorithm

Possessing advantages such as high computing efficiency and ease of programming,the Symplectic Euler algorithm can be applied to construct a groundpenetrating radar(GPR)wave propagation numerical model for complex geoelectric structures.However,the Symplectic Euler algorithm is still a difference algorithm,and for a complicated boundary,ladder grids are needed to perform an approximation process,which results in a certain amount of error.Further,grids that are too dense will seriously decrease computing efficiency.This paper proposes a conformal Symplectic Euler algorithm based on the conformal grid technique,amends the electric/magnetic fieldupdating equations of the Symplectic Euler algorithm by introducing the effective dielectric constant and effective permeability coefficient,and reduces the computing error caused by the ladder approximation of rectangular grids.Moreover,three surface boundary models(the underground circular void model,the undulating stratum model,and actual measurement model)are introduced.By comparing reflection waveforms simulated by the traditional Symplectic Euler algorithm,the conformal Symplectic Euler algorithm and the conformal finite difference time domain(CFDTD),the conformal Symplectic Euler algorithm achieves almost the same level of accuracy as the CFDTD method,but the conformal Symplectic Euler algorithm improves the computational efficiency compared with the CFDTD method dramatically.When the dielectric constants of the two materials vary greatly,the conformal Symplectic Euler algorithm can reduce the pseudo-waves almost by 80% compared with the traditional Symplectic Euler algorithm on average.

Anisotropic Plane Symmetric Two-Fluid Cosmological Model with Time-Varying G and A

We investigate a two-fluid anisotropic plane symmetric cosmological model with variable gravitational constant G（t） and cosmological term A（t）. In the two-fluid model, one fluid is chosen to be that of the radiation field modeling the cosmic microwave background and the other one a perfect fluid modeling the material content of the universe. Exact solutions of the field equations are obtained by using a special form for the average scale factor which corresponds to a specific time-varying deceleration parameter. The model obtained presents a cosmological scenario which describes an early acceleration and late-time deceleration. The gravitation constant increases with the cosmic time whereas the cosmological term decreases and asymptotically tends to zero. The physical and kinematical behaviors of the associated fluid parameters are discussed.

The Corrected Simulation Method of Critical Heat Flux Prediction for Water-Cooled Divertor Based on Euler Homogeneous Model

An accurate critical heat flux（CHF） prediction method is the key factor for realizing the steady-state operation of a water-cooled divertor that works under one-sided high heating flux conditions.An improved CHF prediction method based on Euler＇s homogeneous model for flow boiling combined with realizable k-ε model for single-phase flow is adopted in this paper in which time relaxation coefficients are corrected by the Hertz-Knudsen formula in order to improve the calculation accuracy of vapor-liquid conversion efficiency under high heating flux conditions.Moreover,local large differences of liquid physical properties due to the extreme nonuniform heating flux on cooling wall along the circumference direction are revised by formula IAPWSIF97.Therefore,this method can improve the calculation accuracy of heat and mass transfer between liquid phase and vapor phase in a CHF prediction simulation of water-cooled divertors under the one-sided high heating condition.An experimental example is simulated based on the improved and the uncorrected methods.The simulation results,such as temperature,void fraction and heat transfer coefficient,are analyzed to achieve the CHF prediction.The results show that the maximum error of CHF based on the improved method is 23.7%,while that of CHF based on uncorrected method is up to 188%,as compared with the experiment results of Ref.[12].Finally,this method is verified by comparison with the experimental data obtained by International Thermonuclear Experimental Reactor（ITER）,with a maximum error of 6% only.This method provides an efficient tool for the CHF prediction of water-cooled divertors.

Numerical Simulation of Countercurrent Flow in a PWR Hot Leg by Using Two-Fluid Model

In order to evaluate CCFL （countercurrent flow limitation） characteristics in a PWR （pressurized water reactor） hot leg under reflux condensation, numerical simulations have been conducted using a 2F （two-fluid） model and a VOF （volume of fluid） method implemented in the CFD （computational fluid dynamics） software, FLUENT6.3.26. The 2F model gave good agreement with CCFL data in low pressure conditions but did not give good results for high pressure steam-water conditions. In the previous study, the computational grid and schemes were improved in the VOF method to improve calculations in circular tubes, and the calculated CCFL characteristics agreed well with the UPTF （Upper Plenum Test Facility） data at 1.5 MPa. In this study, therefore, using the 2F model and the computational grid previously improved for the VOF calculations, numerical simulations were conducted for steam-water flows at 1.5 MPa under PWR full-scale conditions. In the range of medium gas volumetric fluxes, the calculated CCFL characteristics agreed well with the values calculated by the VOF method and the UPTF data at 1.5 MPa. This indicated that the reference set of the interfacial drag correlations employed in this study could be applied not only to low pressures but also to high pressures.

Quantum geometric tensor and the topological characterization of the extended Su-Schrieffer-Heeger model

We investigate the quantum metric and topological Euler number in a cyclically modulated Su-Schrieffer-Heeger(SSH)model with long-range hopping terms.By computing the quantum geometry tensor,we derive exact expressions for the quantum metric and Berry curvature of the energy band electrons,and we obtain the phase diagram of the model marked by the first Chern number.Furthermore,we also obtain the topological Euler number of the energy band based on the Gauss-Bonnet theorem on the topological characterization of the closed Bloch states manifold in the first Brillouin zone.However,some regions where the Berry curvature is identically zero in the first Brillouin zone result in the degeneracy of the quantum metric,which leads to ill-defined non-integer topological Euler numbers.Nevertheless,the non-integer"Euler number"provides valuable insights and an upper bound for the absolute values of the Chern numbers.

基于Euler-Euler模型的空气重介质流化床密度分布特性

以Geldart B类磁铁矿粉为主体加重质,采用试验测量与基于Euler-Euler多相流模型的数值计算相结合的方法,考察流化床沿床层高度方向和轴向的密度分布特性。结果表明:当操作气速控制在1.50Umf≤U≤2.20Umf时,床层密度沿床层高度方向与轴向位置的分布范围分别为1.95～2.10 g/cm3与2.00～2.10 g/cm3,两者的密度标准差均小于0.20 g/cm3。其中,轴向密度稳定性要高于床高方向密度稳定性,因此在实际分选过程中要侧重保持沿床高方向的密度波动性最小,进而提高流化床三维空间内的密度均匀稳定性,试验测量与数值模拟结果基本吻合。

改进的6-DOF并联机器人Newton-Euler动力学模型

本文在 6 - DOF并联机器人运动模型的基础上 ,采用对加速度及作用力正交分解的方法 ,将其 Newton- Euler动力学模型归结为一个简单的、可用于实时计算的模型 .

基于Euler多相流模型的卧螺离心机速度场数值模拟与分析

应用计算流体力学软件Fluent,基于Euler多相流模型,在多重参考系坐标下,选用RNG k-ε湍流模型,对卧螺离心机内部的三维速度场进行了数值模拟和分析。结果表明:当液体进入转鼓后,对沉降分离起主要作用的周向速度迅速增大,经过较短的距离即可获得稳定的流动状态,且沿转鼓轴向变化较小;轴向速度沿径向的梯度在转鼓柱段较小,而在锥段较大,且在靠近转鼓的区域,锥段的轴向速度比柱段的大;径向速度复杂多变,无明显规律,流动受几何结构的影响很大。

Euler网仿真建模方法

本文介绍Ｅｕｌｅｒ网仿真建模方法。这种方法是在图论和网论的指导下，在活动周期图建模方法基础上发展起来的。ＳｉｍＳｔｕｄｉｏ仿真环境的研制和应用实践表明。

基于Euler模型的水平流对底沙的输运过程模拟

基于液固两相流动的Euler双流体模型,结合颗粒动力学理论,对颗粒相(沙)进行拟流体化处理,对近岸水域水平流环境下的泥沙起运进行了数值模拟研究。研究结果表明:随着水平射流的不断推进,水平射流对底层沙的影响范围与深度不断增大,导致水平流对底层沙的起运和输送过程显著。水平流的速度越快,起运与输送作用越强烈与迅速。水平流的入射高度与底层沙表面之间的距离越小,水平流对底沙的扰动、起运过程越明显。研究结论可为研究海床的冲刷机理、航道回淤疏浚等提供一定的参考依据。

利用生物量动态模型与Euler-Lotka方程估算亲体-补充量模型的陡度参数

陡度是亲体与补充量模型中的关键参数,能反映补充量受亲体量的约束程度,但该参数难以通过渔业资源评估模型直接估计,而随意假设则可能会降低渔业资源评估结果的可靠性。因此,本文提出了利用生物量动态模型(Biomass dynamic model)与Euler-Lotka方程估计陡度经验分布的方法。先利用贝叶斯生物量动态模型估计内禀增长率的分布,在此基础上,利用Euler-Lotka方程估计陡度的经验分布,再以印度洋长鳍金枪鱼(Thunnus alalunga)陡度估计为例,展示了该方法。研究表明:陡度的估计受资源丰度指数、自然死亡系数、性成熟率、生长参数等数据的影响;当使用中国台湾延绳钓渔业在15°S^45°S、55°E^100°E海域的标准化CPUE、4种自然死亡系数与4种性成熟率时,生物量动态模型能较好估计内禀增长率,估计的陡度均值在0.80~0.87之间,与大西洋、北太平洋长鳍金枪鱼陡度值基本一致,估计结果具有合理性;同时,本文陡度估计支持印度洋长鳍金枪鱼资源处于健康状态的判断。研究结果将进一步丰富陡度估计方法,为陡度的合理假设及印度洋长鳍金枪鱼的资源评估提供理论支持。

车辆-轨道系统振动响应分析——Timoshenko梁与Euler梁轨道模型的比较

近年来,铁路的高速化、高运量化以及轻微的地震灾害等因素加速了轨道结构的沉降或变形,导致车辆轨道系统振动的加剧。本文运用车辆-轨道耦合动力学理论,编制了基于Timoshenko梁钢轨模型的车辆-轨道耦合振动仿真分析软件,分析了车辆-轨道系统的垂向振动特性,并与基于Euler梁模型的VICT软件的仿真结果进行了比较分析。结果表明:仿真结果与VICT的仿真结果基本一致,但在较高频域,前者能更好地反映轮轨系统的高频特性。因而,在研究轮轨高频振动及轮轨噪声时,采用Timoshenko梁钢轨模型更具合理性。

基于Euler Bernoulli理论的压电系统集中参数模型修正

针对压电俘能系统悬臂梁结构集中参数模型的局限性,引入Euler Bernoulli梁振动模型。通过分析两模型在振动时相对位移传递率发现,集中参数模型在基础激励情况下,传递率峰值存在较大偏差。理论分析Euler Bernoulli及集中参数模型在1阶模态附近位移传递率函数,对集中参数模型进行修正。仿真及有限元结果表明修正后的集中参数模型相对位移传递率峰值与Euler Bernoulli模型在低阶模态吻合良好。

Euler方程的二速度三熵级格子Boltzmann模拟

提出了一个新的用于模拟可压缩Ｅｕｌｅｒ方程的格子Ｂｏｌｔｚｍａｎｎ模型。数值试验表明它可以模拟具有激波和接触面的问题。计算结果与经典算法的结果可以比较。

引水隧洞施工通风Euler-Lagrange两相流大涡模拟

目前,地下通风两相流研究主要集中在矿井巷道通风且研究多采用雷诺时均法,无法准确获取湍流瞬态信息以及尘粒在湍流脉动影响下的瞬时运移规律.本文基于分子动理学理论,建立考虑热交换的三维非稳态EulerLagrange两相流颗粒轨道大涡模型,实现了对引水隧洞施工通风两相流的大涡数值模拟,揭示了引水隧洞风流场瞬态发展机制及颗粒在大涡结构影响下的运移规律,并验证了模型的准确性.运用该模型模拟某水电站引水隧洞施工通风排尘过程,结果表明:大涡模拟能捕捉到湍流脉动细节,结果较雷诺时均法更接近实际;通风可有效降低工作面附近温度;颗粒分布由初始的颗粒簇逐渐弥散,最终对隧洞全断面造成污染;通风3,700,s后,绝大多数颗粒从隧洞出口排出.

基于Gauss滤波和Euler修复模型的SAR图像去噪

针对二阶偏微分模型(Total variation,TV)在合成孔径雷达(Synthetic aperture radar,SAR)图像去噪时会产生阶梯效应的问题,结合Euler修复正则项的优点,提出一种基于Euler修复正则项的高阶变分模型应用到图像去噪。为有效求解模型,采用加性算子分裂(Additive operating splitting,AOS)方法进行数值离散。迭代方式为半隐式,克服了显示格式对步长的限制。试验结果表明,仿真实验取得了很好的效果,而对真实的SAR图像,去噪图像会有明显的孤立大颗粒噪声存在,使视觉效果不好。针对此问题,本文又提出一种将Gauss滤波和Euler修复模型相结合的复合模型,数值实验表明,该方法有效地消除了大颗粒噪声,阶梯效应也被有效抑制。