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.

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 ±1 . 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.

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.

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.

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.

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.

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。

沿海欠发达地区乡村经济的区域分异与驱动机制——以浙江省遂昌县为例

为探索沿海欠发达县域乡村经济的区域分异现象,本研究以浙江遂昌县为例,运用泰尔指数与多种空间分析方法,分析2012—2021年该地区村域经济的时空分异规律并探索其驱动机制。研究结果表明:(1)区域差异的时序演化可以划分为振荡调整期、差异上行期和振荡下行期,有明显缩小趋势;从区域差异的贡献度对比看,人口与经济不匹配会导致其组内差异累计值偏高。(2)空间分布的“中心—外围”分层现象明显,高值集聚区主要集中在县域中部的大拓镇和石练镇,低值区大多分布在周边地势较高的村镇;高经济水平村对外辐射效应受地形影响较大,地势平坦的村受益更多,而不是呈圈层式外溢。(3)经济重心位置一直处于大拓镇范围内,但呈现沿西南—东北方向的小范围偏移现象;在研究期后期,当县域西南方向的乡村经济发展表现出“后来居上”时,经济的重心、主体区域和方位角表现出较高一致性。(4)驱动机制的测度结果显示,政策扶持和区位优势驱动因子的单因子或交互组合因子q值要普遍大于其他因子的交互结果;“先天性”的资源条件既可以是快速发展的基础,也可以是经济发展亟需突破或者加以利用的关键所在;政策发挥着引领作用,是促进区域经济差异缩小的外在力量,是物质交换的保障。

Securing Forwarding Layers from Eavesdropping Attacks Using Proactive Approaches

As an emerging network paradigm,the software-defined network(SDN)finds extensive application in areas such as smart grids,the Internet of Things(IoT),and edge computing.The forwarding layer in software-defined networks is susceptible to eavesdropping attacks.Route hopping is amoving target defense(MTD)technology that is frequently employed to resist eavesdropping attacks.In the traditional route hopping technology,both request and reply packets use the same hopping path.If an eavesdropping attacker monitors the nodes along this path,the risk of 100%data leakage becomes substantial.In this paper,we present an effective route hopping approach,called two-day different path(TDP),that turns communication paths into untraceable moving targets.This technology minimizes the probability of data leakage by transmitting request data and reply data through different paths.Firstly,a brief introduction to the network model and attack model involved in this paper is given.Secondly,the algorithm and processingmethod of the TDP are proposed.Thirdly,the paper proposes three differentmetrics tomeasure the effectiveness of the proposed approach.Finally,theoretical analysis and simulation results show that the TDP can effectively reduce the percentage of data exposure,decrease eavesdropping attack success probability,and improve the unpredictability of the path.

中国式现代化道路的早期探索:对工农产品剪刀差的一种解释

在中国式现代化道路的早期探索中,工农产品剪刀差发挥了重要作用,为改革开放及新时代中国式现代化道路的继续探索提供了物质基础。英国通过工业化走出英国现代化道路,李嘉图对此作出理论回应,揭示了现代化道路的一般规律。李嘉图认为,工业是经济增长的主导部门,工业增长需具备资本积累和工资调节两个条件,这为中国工农产品剪刀差提供了理论解释。中英现代化实践共同表明,农业积累和非市场化手段对工业起步是必要而有效的。

针对地下室场景4.8 GHz频段传播特性研究

地下室无线网络信号覆盖一直都是关系到人们感知通信的重要民生事件,但由于其空间封闭,使得室外信号难以穿透,严重影响了运营商的服务质量。文中基于入射及反弹射线法/镜像法对典型地下室环境进行建模仿真;研究了4.8 GHz频段下有车体存在和无车体存在时的电波传播特性并对数据进行处理;计算出不同距离的发射机与接收机对应的接收功率和路径损耗,并与1.9 GHz频段相应参数进行了对比,为优化网络覆盖提供了理论依据。通过研究表明,有车体存在时接收功率更大一些,5G频段相比4G频段接收功率更小一些。

江西省碳排放效率与产业结构升级的耦合研究

本文采用包含非期望产出的超效率SBM模型进行碳排放效率测算,并根据已有研究和应用扩展的耦合模型,对11个设区市按耦合程度和耦合特征进行多重分类,以此考察江西省各设区市碳排放效率与产业结构升级的耦合关系。研究表明:江西省碳排放效率和产业结构升级水平在时间和空间格局上存在差异,从地区分布看,各设区市关联度不明显,西北地区总体碳排放效率水平有待提高;从时间维度看,各设区市产业结构升级水平自2010年后一直稳步缓慢上升,但碳排放效率却整体呈下降趋势,且各设区市之间的水平差异较大。综上,江西省应协调好经济发展与生态文明建设之间的关系,在实现产业结构升级的同时控制碳排放量。

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 analysed 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.

粮食安全党政同责落实情况、制度完善与分区域保供路径

实行粮食安全党政同责把粮食安全这个国之大者的重要性提升到崭新的政治高度。2021—2022年,地方党委和政府都把扛稳粮食安全责任作为一项重要政治任务,粮食安全党政同责初步见到实效。下一步,在制度上要细化主产区、产销平衡区和主销区的考核指标并强化考核结果的运用。三大区域在落实粮食安全党政同责、保障粮食供给方面,应采取不同措施:主产区在保障自身粮食供给的同时还要努力增加净调出量,重点是以新增和改造提升高标准农田为主要抓手,进一步夯实粮食生产的“良田”基础;产销平衡区粮食供给主要依靠自己,重点是将新增和改造提升高标准农田与高效节水灌溉、撂荒地整治等工程同步实施,加快补齐粮食生产的农田水利设施短板;主销区粮食供给主要依靠主产区,要在巩固区域内粮食生产的同时积极拓展外部粮源渠道。

京津冀物流业发展时空差异及发展路径研究

以京津冀省、市、县(市、区)、乡(镇)四个行政层级物流业发展相关数据为基础,综合应用DEA、GIS专题图示法、ESDA(探索性空间数据分析)、空间分析法等方法,探究了京津冀不同层级物流业发展时空差异,最后提出了做好京津冀省市域层面物流业的顶层协同设计、加快提升京津冀城市物流业生产效率、做好县市区物流业数据积累和优化布局乡镇域物流业节点等建议。

页岩中固体沥青的识别、演化路径及地质意义——以松辽盆地白垩系青山口组一段为例

在梳理国内外页岩固体沥青研究现状的基础上,以松辽盆地白垩系青山口组一段富有机质页岩为例,对固体沥青的定义、分类、赋存形式和演化路径进行深入研究,探讨固体沥青对成熟度的指示意义及其对储集空间发育的影响。研究表明:①原生显微组分类型差异是造成固体沥青演化路径不同的主要原因,油前沥青多为原位固体沥青,而油后沥青和焦沥青则多为迁移固体沥青;②在未成熟—生油阶段早期,沥青质体、镜质体、惰质体可通过光学特性观察与固体沥青进行区分,藻类体可通过荧光特征与固体沥青进行区分;③扫描电镜下可有效识别原位和迁移固体沥青,受脂族结构减少、芳构化增强的影响,固体沥青反射率随着镜质体反射率的增加而呈线性增加;④生油窗内的固体沥青主要发育残留孔、脱气裂缝和气泡孔3种次生孔隙类型,高成熟阶段的焦沥青发育海绵状孔隙;⑤扫描电镜结合激光拉曼光谱等原位分析技术的应用,可以反映不同类型固体沥青的结构信息,用于有机质迁移路径、动力等微尺度研究。

陕西皮影多维认知差异NVivo质性研究与发展路径构建

目的通过访谈研究者、皮影工作者和游客三个皮影产业发展过程中的主要参与者,对其认知差异和需求进行探识,了解和平衡三者的认知差异,为传承陕西皮影,制定合理可行的发展路径和政策提供科学依据,达到精准施策的作用。方法运用访谈法对三个群体进行半结构化的访谈。以扎根理论思想为指导,利用NVivo12软件作为研究分析工具,完成90份访谈资料的内容编码与质性分析。结论三者的认知差异可归纳为发展情绪、生存状况、政策影响和关注内容4个维度,认知和利益追求存在显著差异。研究者与艺人的成果贡献不能互惠互利、相互支撑,并与游客的现实需求不匹配。传承人与传承群体间得到的社会关注度和支持力度差距大,未能发挥集体存在价值。最后以分析结果为依据,构建了“一引六维”的发展路径,提出了“活化”设计视角可围绕皮影的基础生产工具、设备、设施和文创产品展开,并结合国家“双减”教育背景,指出未来皮影认知教育从体验感受走向职业化成为可能。

基于改进RRT-Connect算法的机械臂运动规划

针对双向快速拓展随机树(RRT-Connect)算法在多障碍物复杂环境下算法收敛速度慢、搜索效率低、采样具有随机性等问题,提出一种基于椭球子集采样的RRT-Connect算法,首先在传统的RRT-Connect算法的基础上,结合目标偏执采样策略和椭球子集采样的优势,构造一种新的采样方法,对采样区域进行约束,在此基础上找到从起始点到目标点的最优路径点集合,并将该路径作为初始路径,通过引入基于三角不等式的路径修剪算法,在迭代过程中对路径不断优化,得到一条从起始点到目标点的代价小、无碰撞路径,最后结合五次多项式差值算法进行路径优化,生成一条路径平滑且曲率连续的优化路径,从而使机械臂沿着该最优路径快速、准确、稳定的到达目标点。实验结果表明,对比原始的RRT-Connect算法,平均规划时间效率提高了30.5%、平均采样点减少了76.74%、平均路径长度缩短了13.22%,该算法在规划过程中收敛速度更快、搜索效率更高、路径优化效果更显著。

成渝地区双城经济圈经济高质量发展空间差异及解释

党的二十大报告指出,高质量发展是全面建设社会主义现代化国家的首要任务。采用Dagum基尼系数、Markov链等分析成渝地区双城经济圈经济高质量发展水平空间变化动态差异,借助Tobit面板模型对上述空间变化进行解释,分析成渝地区双城经济圈高质量协同发展路径。结果表明:成渝地区双城经济圈经济高质量发展水平值呈上升态势;经济圈整体Dagum基尼系数差异表现出“缩减-增强-缩减”的动态变化趋势,区域间相对差异是影响经济圈相对差异的主要因素;传统Markov链和空间Markov链分析结果均证实存在相邻关系的经济高质量发展水平存在较强溢出性;区域创新指数、高技术产业发展水平、区域产业结构、吸引外商投资能力、环境规制强度和碳排放强度等指标能显著提升经济圈经济高质量发展。