Application of shifted lattice model to 3D compressible lattice Boltzmann method

An additional potential energy distribution function is introduced on the basis of previous D3Q25 model,and the equilibrium distribution function of D3Q25 is obtained by spherical function.A novel three-dimensional(3D)shifted lattice model is proposed,therefore a shifted lattice model is introduced into D3Q25.Under the finite volume scheme,several typical compressible calculation examples are used to verify whether the numerical stability of the D3Q25 model can be improved by adding the shifted lattice model.The simulation results show that the numerical stability is indeed improved after adding the shifted lattice model.

基于改进Theil指数和Shift-Share模型的2012—2021年中国产业偏离分析

文章首先通过对现有文献的梳理和分析,发现针对产业偏离的测算,传统的产业偏离度E系数、Theil指数及Shift-Share模型均存在一定的缺陷,E系数和Theil指数的缺陷主要体现在计算原理方面,而Shift-Share模型的缺陷主要表现在参照系选择的合理性和数据采集的可行性方面。然后,基于现有模型的基本原理,提出了更为合理和更具可操作性的产业偏离测算方法,再采用实证研究的方法,根据2012—2021年的数据,对中国的产业偏离情况进行具体分析,得出尽管中国存在产业偏离,但产业偏离度在逐渐减小。最后,基于修正模型的计算结果,并结合当前的国际国内环境,提出如下政策建议:1)第一产业要依靠创新和科技引领,促进农村劳动力在城乡间有序转移,实现农业生产的规模化和现代化;2)第二产业要加快产业的升级换代,建立和保持独立、自主、完整的工业体系,加大在基础研究方面的投入,尽早突破美西方的技术封锁;3)第三产业的发展重点应该在金融和科教两个方面,要进一步提升香港地区、上海和北京等城市的世界金融中心地位,依靠金融创新来规避现行国际金融体系的不利约束和影响,同时要将科教兴国战略落到实处,努力探索适合中国国情的从小学到大学各阶段的教育模式。

Discussion on the Impact of“Shift System”Teaching Model of Physical Education on Students’Mental Health

The“shift system”teaching model of physical education is an emerging education model that aims to improve students’independent choice and personalized development.However,there are also some challenges in the practical application of this model.For example,there are mental health issues for some students including difficulty in adaptation,social interaction,high psychological pressure,etc.Based on this,this article analyzes the impact of the“shift system”teaching model of physical education on students’mental health and explores the optimization path of the physical education“shift system”teaching model in order to promote students’mental health and all-round development.

Existence of Forced Waves and Their Asymptotic for Leslie-Gower Prey-Predator Model with Nonlocal Effects under Shifting Environment

In this paper, we prove the existence of forced waves for Leslie-Gower prey-predator model with nonlocal effects under shifting environment. By constructing a pair of upper and lower solutions with the method of monotone iteration, we can obtain the existence of forced waves for any positive constant shifting speed. Finally, we show the asymptotical behavior of traveling wave fronts in two tails.

Regime Shifts in the North Pacific Simulated by a COADS-driven Isopycnal Model

The Miami Isopycnal Coordinate Ocean Model (MICOM) is adopted to simulate the intevdecadal variability in the Pacific Ocean with most emphasis on regime shifts in the North Pacific. The computational domain covers 60°N to 40°S with an enclosed boundary condition for momentum flux, whereas there are thermohalirie fluxes across the southern end as a restoring term. In addition, sea surface salinity of the model relaxes to the climatological season cycle, which results in climatological fresh water fluxes. Surface forcing functions from January 1945 through December 1998 are derived from the Comprehensive Ocean and Atmospheric Data Set (COADS). Such a numerical experiment reproduces the observed evolution of the interdecadal variability in the heat content over the upper 400-m layer by a two-year lag. Subduction that occurs at the ventilated thermocline in the central North Pacific is also been simulated and the subducted signals propagate from 35°N to 25°N, taking about 8 to 10 years, in agreement with the expendable Bathy Thermograph observation over recent decades. Interdecadal signals take a southwest-ward and downward path rather than westward propagation, meaning they are less associated with the baroclinic planetary waves. During travel, the signals appear to conserve potential vorticity. Therefore, the ventilated thermocline and related subduction are probably the fundamental physics for interdecadal variability in the mid-latitude subtropics of the North Pacific.

Model update mechanism for mean-shift tracking

In order to solve the model update problem in mean-shift based tracker, a novel mechanism is proposed. Kalman filter is employed to update object model by filtering object kernel-histogram using previous model and current candidate. A self-tuning method is used for adaptively adjust all the parameters of the filters under the analysis of the filtering residuals. In addition, hypothesis testing servers as the criterion for determining whether to accept filtering result. Therefore, the tracker has the ability to handle occlusion so as to avoid over-update. The experimental results show that our method can not only keep up with the object appearance and scale changes but also be robust to occlusion.

MODEL SHIFT AND STRANGE ATTRACTOR ON MBIUS STRIP

A new model shift mapping was given in bilateral symbol space. It is topologically conjugate with the traditional shift mapping. Similar to Smale Horseshoe, a model was constructed correspondent to the model shift mapping, i.e., a class of mapping on Mbius strip was given. Its attractors' structure and dynamical behaviour were described.

Investigation on the Doppler shifts induced by 1-D ocean surface wave displacements by the first order small slope approximation theory:comparison of hydrodynamic models

Based on the first order small slope approximation theory （SSA-I） for oceanic surface electromagnetic scattering, this paper predicts the Doppler shifts induced by wave displacements. Theoretical results from three distinct hydrody- namic models are compared： a linear model, the nonlinear Barrick model, and the nonlinear Creamer model. Meanwhile, the predicted Doppler shifts are also compared with the results associated to the resonant Bragg waves and the so-called long waves in the framework of the two-scale model. The dependences of the predicted Doppler shifts on the incident angle, the radar frequency, and the wind speed are discussed. At large incident angles, the predicted Doppler shifts for the linear and nonlinear Barrick models are found to be insensitive to the wind speed and this phenomenon is not coincident with the experimental data. The conclusions obtained in this paper are promising for better understanding the properties of time dependent radar echoes from oceanic surfaces.

Existence of Many Blue Shifted Galaxies in the Universe by Dynamic Universe Model Came True

There are many blue shifted Galaxies in our universe. Here we will see old simulations to make such predictions from the output graphs using SITA simulations. There are four new simulations also presented here. In these sets of simulations, different point masses are placed in different distances in a 3D Cartesian coordinate grid;and these point masses are allowed to move on universal gravitation force (UGF) acting on each mass at that instant of time at its position. The output pictures depict the three dimensional orbit formations of point masses after some iterations. In an orbit so formed, some Galaxies are coming near (Blue shifted) and some are going away (Red shifted). In this paper, the simulations predicted the existence of a large number of Blue shifted Galaxies, in an expanding universe, in 2004 itself. Over 8300 blue shifted galaxies have been discovered extending beyond the Local Group by Hubble Space Telescope (HST) in the year 2009. Thus Dynamic Universe model predictions came true.

面向旋转载体的卫星导航天线相位缠绕问题与分析

为解决卫星导航接收机在小口径旋转导弹应用中无法实现载波连续跟踪问题,本文通过分析小口径旋转导弹接收的卫星导航信号特点,研究载体旋转对接收信号幅度和载波相移的影响,建立载体旋转状态下接收信号的幅度变化模型和载波相移模型,提出了天线相位缠绕会引入额外的载波相移并改进原有的系统模型。依据信号模型进行系统仿真,并搭建了试验环境以证明相位缠绕对载波相位测量引入的误差不可忽略。试验结果表明,本文所改进的相位缠绕系统模型与实测数据均方根误差为11.13°,为卫星导航接收机实现载波跟踪进行精确的相位补偿提供理论依据,进而为提高高速旋转载体卫星导航性能提供理论支撑。

DAB储能变换器双闭环模型预测控制与PI补偿控制策略研究

针对直流微电网中分布式电源输入输出功率不稳定造成的直流母线电压波动问题,鉴于双有源桥(DAB)储能变换器具有能量双向流动的特点,提出一种基于内模原理的双闭环模型预测控制策略。在分析DAB变换器扩展移相调制原理与特性基础上,重点研究电压外环和电流内环的模型预测控制策略。针对模型预测控制性能依赖电路参数准确度问题,分别从电路主要参数失配对功率传输和直流母线稳压的影响两个角度出发,深入分析模型参数敏感度。最终设置直流母线电压稳态误差灵敏度区,在误差灵敏度区外仅采用双闭环模型预测控制以保证系统的动态响应性能,在误差灵敏度区内采用双闭环模型预测控制和PI补偿控制以消除系统稳态误差。搭建实验平台进行实验验证,结果表明:在系统受到扰动时,DAB储能变换器可实现快速地充放电对系统进行补偿,混合控制策略可快速保持母线电压的稳定,实现系统功率均衡,增强系统抗扰能力。

从ChatGPT到Sora:面向AIGC的四能教育和范式革新

AIGC作为集成了文本、图像、视频处理等多功能的技术体系,其多平台、多终端、多模态的“涌现”不仅为教育领域带来技术突破,也构成当前教研体系的挑战与机遇。文章梳理了AIGC的内生价值,提出了面向AIGC的四能教育理论,通过“低能到高能、单能到多能、多能到超能、超能到异能”的智教合一和范式革新,将教学结果过程化,将创新思维工业化,将知识涌现常态化;形成“自生产”和“自适应”的教学理念,从“天人合一”最终达到“天人智一”,共创人机共生的教研环境。文章还提出了面向未来的AIGC教育大模型架构,为利用AIGC技术推动我国教育创新提供了理论依据和实践指导,有助于培养适应未来社会需求的创新型人才。

基于改进Yolov5模型的纱筒余纱量检测方法

为实现针织圆纬机纱架上纱筒余纱量的实时检测,提出一种深度学习与传统图像处理相结合的检测方法。通过优化Yolov5的主干网络并加入Shuffle-Attention注意力机制,利用改进后模型在图像中检测并框出纱筒位置;然后利用透视变换、均值偏移、canny轮廓检测、闭操作等处理获取纱筒内外圆轮廓,设计基于梯度下降的圆拟合算法,拟合纱筒内外圆的轮廓,得到纱筒的内外圆半径;最后结合小孔成像的原理完成纱筒余纱量的测量。结果表明:改进后的Yolov5模型在纱筒检测精度上达到99.5%,检测速度可达20帧/s,同时模型参数减少至3.255×106可检测的最小纱筒余纱量为3 mm,当纱筒余纱量小于3 mm后,将其视为空筒,进行延时更换。本文算法拟合圆所花费时间是传统霍夫圆检测算法的1/4左右,因此可满足针织车间的实际应用需求。

基于Mean Shift的视觉目标跟踪算法综述

基于Mean Shift的视觉跟踪算法具有计算复杂度低、调节参数少、稳健性较好和易于工程实现等优点,是目前视觉跟踪领域的重要研究方向。首先介绍了经典的Mean Shift跟踪算法,分析了此跟踪框架存在的缺陷。然后从目标模型表达、模型更新、尺度与方向估计、抗遮挡跟踪和快速目标跟踪等5个方面详细地综述了Mean Shift跟踪算法的发展与改进。针对上述每个方面,对典型方法与最近研究成果进行了介绍与评述。最后展望了Mean Shift跟踪今后的研究方向与发展趋势。

Shift-Share区域经济评价模型及其扩展研究

讨论了Shift-Share模型的经济思想,指出现有研究反映经济信息的片面性。对Shift-Share方法进行了扩展,提出了产业结构效率新概念,并诠释了其经济思想,构造了更具经济评价和政策意义的区域产业结构分析统计模型,用具体案例介绍了模型使用方法。

铁电光伏效应的理论机制及其研究进展

近期,铁电体的反常光伏效应在太阳能光伏领域引起了广泛关注。基于体光伏效应的铁电光伏器件的内部机制与基于p-n结的传统光伏器件不同。体光伏效应是指在缺乏反演对称性的材料中产生稳定的光电流和超过带隙的光电压。尽管体光伏效应具备巨大应用潜力,但其内部机制尚不明确。回顾了铁电体中铁电光伏效应的理论发展历程和最新进展,重点讨论了体光伏效应的内部机制和理论模型。揭示了对体光伏效应现象与弹道电流、位移电流机制的理论理解及其实验研究。最后,讨论了体光伏效应在未来应用中所面临的机遇和挑战。

基于CamShift的自适应颜色空间目标跟踪算法

CamShift算法只适于特定颜色目标的跟踪,针对这一不足,提出了自适应颜色空间目标跟踪算法。依据当前测量值,根据类间平均距离动态选择当前颜色空间。颜色空间更新判断机制的引入,降低了颜色空间更新带来的时间开销。实验结果表明,该算法可以更准确地在复杂背景下的跟踪各种色彩的目标。

基于直方图比的背景加权的Mean Shift目标跟踪算法

针对Mean Shift跟踪算法目标模型中背景像素所造成的目标跟踪定位的偏差,提出了一种基于直方图比的背景加权的目标表示方法。该方法使用由目标核直方图和背景直方图的对数似然比值推导出的隶属度因子作为权值,通过只对目标模型进行加权变换,而不变换目标候选模型的方法,增强了目标和背景的可分性,有效减少了跟踪过程中背景像素的干扰,提高了目标定位的准确性。仿真实验结果表明算法的有效性。

三有源桥DC-DC变换器广义状态空间平均模型及控制策略研究

基于移相加占空比控制策略的三有源桥TAB(triple active bridge)DC-DC变换器具有效率高和软开关范围可扩展等优点,但其小信号建模过程复杂、闭环控制环路参数整定困难。针对该问题,提出1种TAB工作在移相加占空比控制下的全阶连续广义状态平均建模和PI控制器设计方法。首先,分析TAB的运行原理和Y型等效结构;然后,结合移相加占空比控制的特点和交流方波源等效方法,推导出TAB的广义状态空间平均模型;接着,在推得模型的基础上求得输入到输出的传递函数,设计出PI控制器参数。最后,结合数字仿真及样机实验验证了所提方法的正确性及有效性。

一种新的Mean-Shift对象跟踪方法

由于存在外点干扰,传统的Mean-Shift对象跟踪方法不能有效的跟踪尺寸逐步变大的目标。猜想利用对象初始模型能有效排除外点对跟踪结果的干扰,在此基础上本文提出了一种利用对象初始模型的候选目标模型和相似度测量方法;为了使内核窗口中心及大小与对象形心及大小一致,根据内核窗口外一定宽度子带内像素分布情况,动态调整内核窗口大小和位置。通过对尺寸逐渐变大的汽车进行跟踪,验证了算法的有效性,同时试验结果也证明新算法具有更低的计算复杂度。