The Poisson Distribution Is Applied to Improve the Estimation of Individual Cell and Micropopulation Lag Phases

Many articles dealing with individual cell lag phase determination assume that growth, when observed, comes from one cell. This assumption is not in agreement with the Poisson distribution, which uses the probability of growth in a sample to predict how many samples contain one, two, or some other number of cells. This article analyses and compares different approaches to improve the accuracy of lag phase estimation of individual cells and micropopulations. It argues that if the highest initial load, as predicted by the Poisson distribution, is assigned to the sample with the shortest lag phase, the second highest to the sample with the second shortest lag phase and so on, the resulting lag phase distributions would be more accurate. This study also proposes the use of a robust test, permutation test, to compare lag phase distributions obtained in different situations.

Generalized thermoelastic interaction in functional graded material with fractional order three-phase lag heat transfer

The present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. The governing equations of fractional order generalized thermoelasticity with three-phase lag model for functionally graded materials(FGM)(i.e., material with spatially varying material properties) are established. The analytical solution in the transform domain is obtained by using the eigenvalue approach.The inversion of Laplace transform is done numerically. The graphical results indicate that the fractional parameter has significant effects on all the physical quantities. Thus, we can consider the theory of fractional order generalized thermoelasticity an improvement on studying elastic materials.

Mechanism of Phase Lag Between Current Speed and Suspended Sediment: Combined Effect of Erosion, Deposition, and Advection

To retrieve and explain the phase lag between current speed and suspended sediment concentration(SSC), erosion, deposition, and advection were isolated as primary processes of sediment movement in a three-dimensional model. The response time was proved to be one of the reasons for the phase lag, as time is needed for suspension to diffuse from bottom to surface. A fitted Shields diagram was introduced into the model to reflect the relationship between SSC and shear stress, between shear stress and critical shear stress, as well as between SSC and critical shear stress for erosion. It takes some time for shear stress to increase to the critical value after high or low tide, and this was proved to be an important contributor to the phase lag. Overall, the variation of vertically integrated SSC is influenced by erosion mass flux, deposition mass flux, and advection flux. The phase pattern of erosion mass flux is consistent with the pattern of current if there was no wave action. However, phase difference is produced by the influence of deposition mass flux and advection. In this study, SSC peak/trough mostly occurred near the moment erosion mass flux approximately equaled deposition mass flux and would be impacted by advection. The time required for instantaneous variation of suspension to get to 0 after current peak/trough represents the phase lag between current speed and SSC.

Time fractional dual-phase-lag heat conduction equation

We build a fractional dual-phase-lag model and the corresponding bioheat transfer equation, which we use to interpret the experiment results for processed meat that have been explained by applying the hyperbolic conduction. Analytical solutions expressed by H-functions are obtained by using the Laplace and Fourier transforms method. The inverse fractional dual-phase-lag heat conduction problem for the simultaneous estimation of two relaxation times and orders of fractionality is solved by applying the nonlinear least-square method. The estimated model parameters are given. Finally, the measured and the calculated temperatures versus time are compared and discussed. Some numerical examples are also given and discussed.

A Problem of a Semi-Infinite Medium Subjected to Exponential Heating Using a Dual-Phase-Lag Thermoelastic Model

The problem of a semi-infinite medium subjected to thermal shock on its plane boundary is solved in the context of the dual-phase-lag thermoelastic model. The expressions for temperature, displacement and stress are presented. The governing equations are expressed in Laplace transform domain and solved in that domain. The solution of the problem in the physical domain is obtained by using a numerical method for the inversion of the Laplace transforms based on Fourier series expansions. The numerical estimates of the displacement, temperature, stress and strain are obtained for a hypothetical material. The results obtained are presented graphically to show the effect phase-lag of the heat flux and a phase-lag of temperature gradient on displacement, temperature, stress.

Effects of rotation and gravity on an electro-magneto-thermoelastic medium with diffusion and voids by using the Lord-Shulman and dual-phase-lag models

The effects of rotation and gravity on an electro-magneto-thermoelastic medium with diffusion and voids in a generalized thermoplastic half-space are studied by using the Lord-Shulman (L-S) model and the dual-phase-lag (DPL) model. The analytical solutions for the displacements, stresses, temperature, diffusion concentration, and volume fraction field with different values of the magnetic field, the rotation, the gravity, and the initial stress are obtained and portrayed graphically. The results indicate that the effects of gravity, rotation, voids, diffusion, initial stress, and electromagnetic field are very pronounced on the physical properties of the material.

Green’s Function Solution for the Dual-Phase-Lag Heat Equation

The present work is devoted to define a generalized Green’s function solution for the dual-phase-lag model in homogeneous materials in a unified manner .The high-order mixed derivative with respect to space and time which reflect the lagging behavior is treated in special manner in the dual-phase-lag heat equation in order to construct a general solution applicable to wide range of dual-phase-lag heat transfer problems of general initial-boundary conditions using Green’s function solution method. Also, the Green’s function for a finite medium subjected to arbitrary heat source and arbitrary initial and boundary conditions is constructed. Finally, four examples of different physical situations are analyzed in order to illustrate the accuracy and potentialities of the proposed unified method. The obtained results show good agreement with works of [1-4].

Effects of three-phase-lag on two-temperature generalized thermoelasticity for infinite medium with spherical cavity

The thermoelastic interaction for the three-phase-lag （TPL） heat equation in an isotropic infinite elastic body with a spherical cavity is studied by two-temperature generalized thermoelasticity theory （2TT）. The heat conduction equation in the theory of TPL is a hyperbolic partial differential equation with a fourth-order derivative with respect to time. The medium is assumed to be initially quiescent. By the Laplace trans- formation, the fundamental equations are expressed in the form of a vector-matrix differ- ential equation, which is solved by a state-space approach. The general solution obtained is applied to a specific problem, when the boundary of the cavity is subjected to the ther- mal loading （the thermal shock and the ramp-type heating） and the mechanical loading. The inversion of the Laplace transform is carried out by the Fourier series expansion tech- niques. The numerical values of the physical quantity are computed for the copper like ma- terial. Significant dissimilarities between two models （the two-temperature Green-Naghdi theory with energy dissipation （2TGN-III） and two-temperature TPL model （2T3phase）） are shown graphically. The effects of two-temperature and ramping parameters are also studied.

个体化频带滑动窗特征的轻度认知障碍诊断研究

轻度认知障碍(MCI)是老年性痴呆诊断的关键阶段,脑电(EEG)信号特征可以反映MCI患者的认知状态,帮助实现早期诊断。现有研究在EEG特征提取过程中,针对脑电各节律,大多采用固定的时间窗完成分段处理,忽略了不同节律的特征差异,从而影响诊断效果。针对该问题,本文提出了一种新的组合滑动窗优化算法,该算法通过迭代振幅调整傅里叶变换(IAAFT)对零模型的构建方法进行了改进,以此得到评估大脑动态特性指标KPLI,通过对EEG各频段信号采取多种滑动窗组合,并以KPLI指标引导,得到适合不同频段的最佳滑动窗组合。在最佳滑动窗组合基础上,对各频段组合提取相位滞后指数(PLI),进行连续小波变换(CWT)特征,通过ResNet-MLP双通道分类网络实现MCI诊断。结果显示,使用个性化组合频段滑动窗对88名受试者(32名MCI患者,36名阿尔茨海默症患者以及20名正常对照组)实现了诊断分类,得到了82.2%的分类准确率,比固定窗的分类提高了10%(得到了72.2%的分类准确率)。结果表明,基于个体化脑电节律特征组合能够更好提取MCI的特征,提高轻度认知障碍诊断的正确率与特异性,是一种有效的脑电特征提取方法。

2023年2月6日土耳其两次7.8级地震引起的井水位同震响应对比分析

2023年2月6日,土耳其发生的两次7.8级地震引起了新疆乌鲁木齐地区新04井、新10井和新11井的同震响应,但同震变化形态各有不同。本文对比分析了这三口观测井水位的同震响应特征,探讨了地震引起的井水位同震响应机理。结果显示,本研究中的三口观测井水位的同震响应类型有振荡、同震下降和同震上升三种。其中,新10井表现为振荡,而新04井和新11井则分别表现为同震下降和上升,表明井水位同震变化机理的复杂性。两次地震在同一观测井的同震响应形态一致,不同观测井水位同震变化与井孔所在位置的渗透性结构改变有关。

平原河网地区稻田农药脉冲输出迟滞分析研究

针对目前有关稻田施药后短期内农药的脉冲式输出过程及运移机理尚不十分明确的问题,以扬州市江都区农田水利科学研究站的试验稻田为研究区,针对稻田施药后农药面源污染物与排水的双脉冲输出过程开展高频监测,捕捉到毒死蜱、阿维菌素、三环唑和噻呋酰胺等4种水稻常用农药的脉冲式输出过程,结果显示:上述4种农药的输出浓度和负荷率峰值均发生在施药后2.5~5h内,输出脉冲特征明显.农药和排水双脉冲的相位关系受人为因素影响较大,呈现一定的随机性.对于淋溶性较好、受田间水文状况影响较大的农药(以杀菌剂三环唑和噻呋酰胺为代表),其迟滞指数分别为0.419和0.326,首次观察到较为明显的c-Q迟滞现象,该现象的发生与稻田施药先后顺序以及农药施入稻田后随水流运移到农沟水体的路径长短有关;而对挥发性较大的农药(以杀虫剂毒死蜱为代表),其迟滞系数仅为0.083,由于易受风向等不确定性因素影响未能观察到明显的迟滞现象.上述3种农药的FI值均等于或接近于1,说明排水脉冲对农药以富集作用为主.

基于加权相位滞后指数热力图的脑力负荷识别

脑力负荷识别对提高人机交互操作人员的工作绩效具有重要意义。目前已有研究表明,通过提取脑电(electroencephalogram,EEG)信号的能量特征进行脑力负荷识别取得了不错的分类效果。但该方法只关注到信号的幅度信息,而忽略了相位信息;只分析了各个通道的频域特征,没有考虑不同通道信号之间的同步关系。为充分考虑不同脑区间的功能连接性,提出一种基于加权相位滞后指数(weighted phase lag index,WPLI)热力图的脑力负荷分类方法。对预处理后的脑电信号计算两两通道间的WPLI并绘制热力图,用于评估不同通道信号之间的相位耦合情况,由此反映不同脑区间的功能连接性。由WPLI热力图可以直观地观察到:在高、低负荷状态下,大脑功能连接性的分布存在明显差异。通过实验分别对能量特征图和WPLI热力图采用方向梯度直方图-支持向量机(histogram of oriented gradient-support vector machine,HOG-SVM)和LeNet-5两种方法进行分类。结果表明:WPLI热力图和LeNet-5的组合具有较好的分类结果。

基于加权相位延迟指数的阿尔茨海默病静息态脑电图定量分析

目的分析阿尔茨海默病(AD)、轻度认知功能障碍(MCI)患者定量脑电图的特征,探讨定量脑电图在早期检测和评估认知衰退方面的效用。方法本研究选取AD患者、MCI患者和认知功能正常的老年人作为研究对象,采用64导脑电图记录静息状态下脑电信号,通过加权相位延迟指数(wPLI)分析人组患者全脑功能连接的差异性。结果AD组在θ频段的相对功率超过对照组,在β频段则低于对照组。此外,三组间的功能连接呈现差异性。在θ和频段,AD组不同脑区之间的相位同步性增强。而在α频段中,AD组局部脑区之间功能连接强度减弱。同时,θ和β频段下的全脑电极平均相功率改变均与临床认知评估量表呈现相关关系。结论定量脑电图分析显示AD患者脑波存在频率慢化的特点。另外,AD患者同时存在脑网络皮层神经通路功能代偿和失连接现象。

Shear mechanical properties and frictional sliding responses of rough joint surfaces under dynamic normal displacement conditions

A comprehensive understanding of the dynamic frictional characteristics in rock joints under high normal load and strong confinement is essential for ensuring the safety of deep engineering construction and mitigating geological disasters.This study conducted shear experiments on rough rock joints under displacement-controlled dynamic normal loads,investigating the shear behaviors of joints across varying initial normal loads,normal loading frequencies,and normal loading amplitudes.Experimental results showed that the peak/valley shear force values increased with initial normal loads and normal loading frequencies but showed an initial increase followed by a decrease with normal loading amplitudes.Dynamic normal loading can either increase or decrease shear strength,while this study demonstrates that higher frequencies lead to enhanced friction.Increased initial normal loading and normal loading frequency result in a gradual decrease in joint roughness coefficient(JRC)values of joint surfaces after shearing.Positive correlations existed between frictional energy dissipation and peak shear forces,while post-shear joint surface roughness exhibited a negative correlation with peak shear forces through linear regression analysis.This study contributes to a better understanding of the sliding responses and shear mechanical characteristics of rock joints under dynamic disturbances.

风速对光纤复合相线覆冰监测有效性分析

为分析环境温度呈正弦函数变化时光纤复合相线覆冰时温度变化特性及风速对光纤复合相线覆冰监测有效性的影响,考虑风速影响建立环境温度呈正弦时变函数变化时光纤复合相线覆冰温度场模型,分析趋肤效应的焦耳热、风速、环境温度均值及波动幅值对光纤复合相线温度场的影响,研究了环境温度、风速、覆冰厚度与光纤复合相线覆冰与未覆冰时温差变化曲线及光纤复合相线温度滞后相位关系,定义了临界风速并给出基于光纤复合相线温度滞后相位的临界风速计算公式。研究表明,焦耳热对光纤复合相线温度影响较小,风速、覆冰厚度对光纤复合相线温度滞后相位影响较大,环境温度均值与波动幅值对光纤复合相线温度滞后相位影响较小但波动幅值对光纤复合相线温差影响较大。

一种提高数字控制LCL型并网逆变器对电网阻抗鲁棒性的补偿策略

与模拟控制相比,采用数字控制的LCL型并网逆变器会引入控制延迟,在电网阻抗变化较大的弱电网中,严重降低了系统的稳定性。为了提高数字控制的LCL型并网逆变器对电网阻抗变化的鲁棒性,提出一种比例-相位滞后的补偿策略。首先,在考虑控制延时的基础上,对电网阻抗宽变化范围内的系统进行稳定性分析;然后基于Nyquist稳定性判据识别稳定区域,并合理设计比例和相位滞后补偿器的参数,使改进后的系统在电网阻抗宽变化范围时仍能够稳定运行。最后,仿真与半实物实验结果验证了所提方法的可行性和有效性。

基于长期验潮站信息的潮汐分析模型改进

论文基于长期验潮站数据分析结果,利用实际分潮的振幅比和迟角差,在传统的分潮合并理论的基础上,设计和实现了一种新的用于月尺度和年尺度分析的交近点改正方法,目的在于精化潮汐参数的提取,提高短期潮汐分析和预报的精确度。论文给出了合并模型的具体推导过程和计算方法;做了厦门某验潮站548分潮19年的潮汐调和分析,得出相应分潮的调和常数,将选取分潮的振幅比和迟角差用于潮汐短期调和分析;实验验证表明利用新的分潮合并策略进行的潮汐月调和分析和年调和分析得到的调和常数更加接近分潮的长期分析结果,有效提高了潮汐参数的分析精度。

基于脑功能网络的抑郁脑电信号分类方法

通过探究多种脑功能网络构建方法在抑郁脑电信号分类中的性能,提出了一种基于相位滞后指数、自适应阈值和卷积神经网络的高精度抑郁脑电信号分类方法。首先,利用不同连通性方法和二值化方法的组合构建了多种抑郁脑功能网络;然后,基于图论分析从脑功能网络中提取网络参数;最后,将脑网络参数输入多种分类器,实现抑郁脑电信号分类。此外,建立了一种基于可分性测度和量子粒子群优化的自适应阈值法和自适应密度法,以避免人工设置阈值和网络密度的主观性。实验结果表明:与其他常用方法相比,在alpha频带上,所提分类方法的性能最好,分类准确率和灵敏度分别为88.03%、89%。

RCC坝料改进刚度指标及压实质量综合评估研究

有效控制碾压混凝土压实质量是确保大坝安全稳定运行的前提。本文提出了考虑滞后相位角的碾压混凝土坝料改进刚度指标,并给出了滞后相位角的测定方法;结合耦合滞后相位角改进刚度指标、坝料特性参数、碾压参数和频域压实指标,提出了基于XGBoost算法的碾压混凝土压实质量综合评估方法。实例分析表明,改进刚度指标能够更好表征坝料压实质量,综合评估模型的决定系数约为0.86,表明模型精度较高,计算压实度与实测压实度的相对误差平均值为0.47%。本文方法为碾压混凝土坝施工压实质量控制提供了新的有效途径。

Predicting Net Cross-Shore Total Load Transport: A Phase-Averaging, Quasi-Steady Approach Incorporating Undertow Contribution

Wave shapes that induce velocity skewness and acceleration asymmetry are usually responsible for onshore sediment transport, whereas undertow and bottom slope effect normally contribute to offshore sediment transport. By incorporating these counteracting driving forces in a phase-averaged manner, the theoretically-based quasi-steady formula of Wang （2007） is modified to predict the magnitude and direction of net cross-shore total load transport under the coaction of wave and current. The predictions show an excellent agreement with the measurement data on medium and fine sand collected by Dohmen-Janssen and Hanes （2002） and Schretlen （2012） in a full-scale wave flume at the Coastal Research Centre in Hannover, Germany. The modified formula can predict the net onshore transport of fine sand in sheet flows. In particular, it can predict the net offshore transport of medium sand in rippled beds through enlarged bed roughness, as well as the net offshore transport of fine-to-coarse sand in sheet flows with the aid of a new criterion to judge the occurrence of net offshore transport.