Effects of optical axis direction on optical path difference and lateral displacement of Savart polariscope

A simple method is applied to calculating the optical path difference （OPD） of a plane parallel uniaxial plate with an arbitrary optical axis direction. Then, the theoretical expressions of the OPD and lateral displacement （LD） of Savart polariscope under non-ideal conditions are obtained exactly. The variations of OPD and LD are simulated, and some important conclusions are obtained when the optical axis directions have an identical tolerance of ／pm 1^{{／circ}}. An application example is given that the tolerances of optical axis directions are gained according to the spectral resolution tolerances of the stationary polarization interference imaging spectrometer （SPIIS）. Several approximate formulae are obtained for explaining some conclusions above. The work provides a theoretical guidance for the optic design, crystal processing, installation and debugging, data analysis and spectral reconstruction of the SPIIS.

Hierarchical robot control structure and Newton's divided difference approach to robot path planning

A hierarchical robot control is proposed for robot soccer system. The Newton’s divided difference is utilized in robot path planning. This paper describes the problems encoutered, software design considerations, vision algorithm and controls of individual robots. The solutions to the problems implemented are simple and direct. It is observed that many of the ideas and solutions can be evolved based on simple theories and concepts. This paper focuses on software structure of multi agent controls, vision algorithm and simple path planning method.

A Doppler Location Method Based on Virtual Path Difference

This paper presents a Doppler passive location method for moving targets with fixed single station using the Doppler frequency shift and time difference information.First,based on the relationship between frequency shift and path difference,the virtual path difference is calculated from the measured value of Doppler frequency shift by means of mean value correction.Then,under the assumption that the target is moving at a constant speed along a straight line,two coaxial virtual double base arrays are constructed by using the moving track of the moving target based on the method of fixed period time difference.On this basis,the moving distance of the moving target can be calculated by using the ratio relationship between the frequency difference and the radial distance between the two adjacent detection points in the middle of the array,and the linear solution of the two double base path difference positioning equations.At this point,the relative coordinate position of the moving target can be obtained by directly using the linear solution of the double base path difference positioning equation again.

MFPL:Multi-Frequency Phase Difference Combination Based Device-Free Localization

With the popularity of indoor wireless network,device-free indoor localization has attracted more and more attention.Unlike device-based localization where the target is required to carry an active transmitter,their frequent signal scanning consumes a large amount of energy,which is inconvenient for devices with limited energy.In this work,we propose the MFPL,device-free localization(DFL)system based on WiFi distance measurement.First,we combine multi-subcarrier characteristic of Channel State Information(CSI)with classical Fresnel reflection model to get the linear relationship between the change of the length of reflection path and the subcarrier phase difference.Then we calculate the Fresnel phase difference between subcarrier pairs with different spacing from CSI amplitude time series.Finally,we get the change of the length of the reflection path caused by target moving to achieve distance measurement and localization.Using a combination of subcarriers with different spacing to achieve distance measurement effectively broadens the maximum unambiguous distance of the system.To solve the complex non-linear problem of the intersection of two elliptic equations,we introduce Newton's method to transform the non-linear problem into a linear one.The effectiveness of our approach is verified using commodity WiFi infrastructures.The experimental results show our method achieves a median error of 0.87 m in actual indoor environment.

Surface crack imaging based on delayed temperature difference at symmetric points by laser spot thermography

Laser spot thermography is a novel technique for the detection of surface cracks with a laser to heat sample locally and with an IR camera to record the surface temperature distribution. Common methods to characterize cracks are only suitable for the situation that the laser scanning path is vertical to the crack. But due to the randomness of cracks,when the scanning path is parallel to the crack,surface cracks cannot be detected by these methods. To tackle this problem,a method is presented which is suitable for the situation that the scanning path is parallel to crack. The main idea is to evaluate the crack-caused asymmetries of the surface temperature distribution. The effect of temperature gradient and the maximum scanning interval are analyzed by a 2D simulation. A new crack imaging technique is presented that is based on delayed temperature difference at symmetric points to characterize the crack in the thermal image. Compared well with those obtained by the spatial first derivative method,experimental results are shown to efficiently prove this method.

Measurement for Phase Difference Rate without Phase Ambiguity

Firstly,the direction finding solution at the midpoint of a single base array is given for the purpose of this paper and the several functions relation between phase and frequency is also described.Then,the expression of phase difference rate is described based on the multichannel phase difference measurement.With stripping time difference item correspond to the baseline length from phase difference rate,a function is extracted which signifies the differential characteristics of wavelength integer and phase difference in a unit of length.Simulation calculation found that the variation of differential function of path difference in a unit of length is very regular.The corresponding corrected value can is determine directly by distinguishing the range of differential item of phase difference obtained by actual measurement.Thus,the function expression can be obtained that is equivalence with the quondam differential function of path difference and that is nothing to do with the difference item of wavelength integer.On this basic,several parameters are analyzed by using the method of phase difference measurement without phase ambiguity.The research results in this paper may provide a powerful technical support for engineering practical design related to the phase measuring.

高速飞行器气动光学效应

采用数值模拟、计算光学方法和理论,对超声速飞行器流场进行数值模拟研究,获取不同飞行高度和攻角下光学窗口上方流场的密度分布,根据Gladstone-Dale关系得到光学窗口上方的折射率场,利用光线追迹法计算流场光程差分布情况。对流场光程差的分布情况进行分析,可以得出结论:随着飞行高度的增加,气动光学效应逐渐减弱;随着攻角的增大,气动光学效应逐渐增强。

Analysing the structure of the optical path length of a supersonic mixing layer by using wavelet methods

The nano-particle-based planar laser scattering （NPLS） technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference （OPL）, which is quite crucial for the study of aero-optics, is obtained by post processing. Based on the high spatiotemporal resolutions of the NPLS, the structure of the OPL is ana]ysed using wavelet methods. The coherent structures of the OPL are extracted using three methods, including the methods of thresholding the coefficients of the orthogonal wavelet transform and the wavelet packet transform, and preserving a number of wavelet packet coefficients with the largest amplitudes determined by the entropy dimension. Their performances are compared, and the method using the wavelet packet is the best. Based on the viewpoint of multifractals, we study the OPL by the wavelet transform maxima method （WTMM）, and the result indicates that its scaling behaviour is evident.

云南冬季强降温过程冷空气路径及大气环流差异

基于云南125个测站日平均气温数据,判定了1961—2020年云南冬季95次强降温过程的4种冷空气路径,对比分析了不同路径冷空气对云南降温的影响及大气环流差异.结果表明,东北路径冷空气对云南降温幅度影响最剧烈、影响空间范围最广;偏东路径出现频率最高,偏东路径和偏北路径在降温幅度和影响范围上较为接近;东南路径降温幅度和影响范围最弱,出现频率最低.超前强降温日2 d时,东北路径欧亚大陆500 hPa位势高度场上正高度距平异常区域强度和面积、700 hPa反气旋距平环流强度和西伯利亚高压均为最强,东南路径最弱,偏东路径和偏北路径介于前二者之间.东北路径500 hPa上东亚槽横槽转竖特征最明显,偏东路径和偏北路径东亚槽槽底南压加深,但转竖特征不及东北路径明显;东南路径东亚槽底部较宽广;东北路径副高呈块状面积最小,其它3种路径副高则呈带状,偏东路径副高面积最大.700 hPa上东北路径和偏东路径在日本附近有较强海平面气压负距平发展,朝鲜半岛气旋距平环流较强,其西侧较强的偏北气流引导冷空气进入云南;东南路径和偏北路径在朝鲜半岛气旋距平环流及其西侧的偏北气流较弱.在200 hPa纬向风距平场上,东北路径急流轴附近正负距平区强度最强,偏东路径沿急流轴距平分布为西正东负;东南路径正负距平区强度最弱,负距平区主要分布在急流轴北侧,偏北路径负距平区分布在急流轴南北两侧.

机载米波雷达基于镜面反射多径模型的目标高度计算和距离计算方法研究

本文建立了基于球面的电磁波镜面反射模型,推导了由多径距离计算目标海拔高度的公式和由目标海拔高度计算多径距离的公式,考虑到公式无解析解,依据单调性提出了近似解的二分算法,与迭代算法相比,该算法能够完全收敛于真实解。此外,给出了海面多径产生的条件、多径点的信息特征及多径测高的边界。同一目标的多径点与真实点具有相同的多普勒速度、方位角度,且多径距离与直达波距离满足相应的距离差值,依据该特征,对检测的点迹进行配对,并区分真实点和多径点,可以有效解决多径引起的双航迹和短航迹问题。以外,由多径距离还可以获得目标的海拔高度。最后,基于仿真数据,给出了典型参数下的多径测高精度。

大中小学美育一体化实践课程建设探索——以承德清音会为例

大中小学美育一体化实践课程的建设,目的在于贯穿各学段间的审美教育、情操教育、心灵教育,落实立德树人的根本任务,实现学生核心素养的提升。以承德传统音乐文化“清音会”为例探讨大中小学美育一体化实践课程的建设,通过对当前学校美育课程开设现状的调研发现美育课程覆盖范围有限、内容单一、学段间缺乏衔接等问题。因此,一体化课程建设过程中,首先要充分挖掘传统文化的内涵,厘清传统文化与美育之间的关系,此外,还要确定课程建设的原则与目标,尤其要以高校为中心,发挥智力优势,通过创建清音会美育课程团队,课上教学内容与课外活动互为补充等路径,形成科学、系统、完整的美育课程。

数学成绩的影响因素分析与数学素养提升的探讨——H大学大一新生数学公共课的多维数据分析

数学公共课是大多数专业大一新生的必修课,对学生未来的发展有较大影响。本文依据某“985”高校———H大学大一新生的数学公共课成绩以及问卷调查的真实资料,利用统计方法进行量化分析。从知识、态度、情感3个维度包含的多维指标数据出发,进行了指标间的相关性分析、各个指标对数学成绩的差异性分析、数学成绩的影响因素和预测路径分析,得出相应的结论。并进一步探讨了提升学生数学素养的可行路径。

三峡库区乡村发展主体获得感现状及提升路径——基于重庆巫溪长红村的个案

让人民有较多的获得感、幸福感是党和国家新时期治国理政的伟大方略。近年来,在乡村振兴战略推动下,三峡库区经济社会取得较快发展,人民生活发生了重大变化。他们的获得感如何?文章选取库区的重庆巫溪县长红村为研究对象,通过获得感问卷调查和会见座谈形式获取第一手资料,分析该村三类主体获得感的差异性,探寻导致这种差异的内外因素,并提出提升不同主体获得感的实施路径:增强个体发展能力,激发获得感提升的内生动能;壮大集体经济实力,夯实获得感提升的经济基础;优化乡村治理模式,确立获得感提升的组织体制机制;持续推进落实乡村振兴各项政策,营造获得感提升的宽松环境。

考虑客户满意度的实时取送货路径优化问题

针对即时配送订单出现的动态性、服务客户的满意度、末端配送路网的非对称性,在配送订单的时间窗限制下,建立实时取送货路径优化模型。通过定义并调整非对称网络系数,构建非对称配送网络,提出滚动时域忽略策略(Ignore策略)和滚动时域实时判断策略(Real-time策略)。Ignore策略要求配送员一旦出发,返回配送起点前忽略所有新出现的订单,Real-time策略要求配送途中实时判断当新订单出现时,是否返回起点取货,重新规划配送路线。使用数值仿真软件,在不同非对称系数、客户时间窗、订单数量等的情形下分析策略适用性。数值算例分析表明,Real-time策略适用于网络较大的情形,而网络较小且订单数量较少时,Ignore策略更适用。研究结果可为城市末端合单配送和路径优化策略提供新的思路和参考。

解析中西方乡村振兴的“同”与“不同”——探索理性务实的乡村振兴之路

面对中国城镇化发展进程由量转质的内在需求,乡村振兴是新时期实现城乡融合发展的关键所在。中国当前的乡村振兴既与西方具有共性的方面,但也存在社会制度、具体语境等差异,有必要对二者进行深入的比较剖析,从而促进外来经验与本土化的有机结合与务实落地。首先,文章在梳理中国和西方乡村振兴演进脉络的基础上,阐释了二者的历史共性,包括:化解城乡差距过大的社会矛盾、对乡村价值与环境产生主动需求、面向城乡等值的目标实现等。其次,文章认为中国乡村振兴与西方的差异主要在于城镇化不稳定态、多重战略目标面向、城乡流动限制、复杂严苛规制、新技术经济变革等方面塑造的特殊情景。最后,文章针对当前乡村振兴实践中的问题并基于中国国情,对乡村振兴路径设计提出了五方面的策略建议,包括:空间资源配置、城乡对流机制、乡村空间管控、产业联动发展、治理现代化等。

基于双折射晶体透镜的自干涉全息成像系统

该文介绍了采用α–BBO双折射晶体透镜进行分光和光程差补偿方法,以及使用偏振相机进行单次采集的自干涉全息成像方法。该方法不需要使用额外器件补偿共轴干涉光路的光程差,适用于非相干白光照明情况下日常物体的全息图采集与图像重建。该文推导了再现距离与放大率等重要参数,并在此基础上,搭建了单发成像系统,还进行了实验验证。实验通过单次曝光采集了LED灯组的四幅不同偏振态全息图,并用四步相移法得到复振幅全息图,最后通过图像重建算法反演计算获得准确的再现图像。实验验证了基于α–BBO双折射晶体透镜的单次曝光自干涉全息成像方法的三维成像能力。

不同年份白茶饼主要化学成分及感官品质变化与通径分析

分析不同年份白茶饼的主要化学成分与感官品质变化,以评价白茶饼储藏年份与感官品质的关系。以储藏2年陈至19年的白茶饼为试验材料,测定主要化学成分,结合感官评价,利用主成分分析、聚类分析、相关性分析、多元线性回归及通径分析,探讨主要化学成分与感官品质之间的关系。随着储藏年份的增长,茶多酚、游离氨基酸和茶红素含量呈下降趋势,最低值分别为50.71,5.78 mg/g和6.82 mg/g;而总黄酮、茶褐素呈上升趋势,最高值分别为62.18 mg/g和27.09 mg/g。主成分分析、感官分析表明,储藏4年的白茶饼的内质综合排名第1,感官品质最高(总分为96.8),具有最佳品质。聚类分析表明白茶饼储藏第2年、第4年和第6年时转化反应剧烈,而8~19年趋于稳定且感官品质逐渐上升。通径分析得出不同年份白茶饼感官品质的变化,咖啡碱含量与陈化白茶饼感官品质呈显著正相关,总黄酮含量呈显著负相关。白茶饼感官品质以储存4,10,19年的整体较佳。咖啡碱和总黄酮含量可作为评价陈年白茶饼品质的直接因素。

差序格局下高职中外合作办学高质量发展路径研究

在“十四五”时期教育对外开放的背景下,封闭的高等教育系统已被打破,我国职业院校与国际主体间交流日益紧密,高质量发展成为新时代对高职院校中外合作办学的核心要求。当前教育对外开放政策、职业教育发展规划、社会需求、资源分配等多方面的因素共同形成了高职中外合作办学差序格局。通过不同的半径对高职中外合作办学差序格局进行观察与分析,探究高职中外合作办学差序格局形成的动力机制,分析当前存在的问题,探索新时代高职中外合作办学质量提升的对策。

中国新质生产力发展水平测度与时空演进

发展新质生产力是推动经济高质量发展的内在要求和重要着力点,对于加快实现中国式现代化具有重要意义。文章基于2015—2022年中国30个省份的面板数据,构建了中国新质生产力发展水平评价指标体系,并运用熵值法进行测算分析,运用Dagum基尼系数法、核密度估计法、全局以及局部莫兰指数分析新质生产力发展的时空演进特征。结果表明:第一,中国总体、四大地区新质生产力发展水平呈逐年上升状态,但存在区域差异,四大地区呈“东部—中部—东北—西部”递减状态;第二,中国新质生产力发展水平总体差异及东部、中部、东北地区区域内差异呈上升的趋势,西部地区区域内差异呈下降的趋势。四大地区中,区域间差异是新质生产力发展总体差异的主要来源;第三,新质生产力发展呈现空间正相关性,且东部地区多呈现“H-H”型集聚,中部、西部以及东北地区多呈现“L-L”型集聚。

基于通道光谱的长基线恒星光干涉光程差检测方法研究

干涉条纹快速捕获及稳定跟踪是长基线恒星光干涉的关键技术,其难点在于如何实现大动态范围、高精度光程差检测。面向天文观测需求,提出一种基于通道光谱的光程差检测方法,该方法将干涉星光进行色散,在光谱上形成多个探测通道,有效提升了相干检测范围,结合周期图与充零算法实现高精度光程差检测。实验结果表明,该方法在500~600 nm检测范围,检测精度可以达到0.75μm,动态范围达到±195μm,相关研究工作可为我国正在建设中的百米长基线恒星光干涉仪提供关键技术支撑。