Material,energy and spatial fields for metallogenic prediction:Theory and practice An example:Limu Sn polymetallic crisis mines

The Limu tin deposits located in the Nanling tin and tungsten-polymetallic ore belt are now facing resource depletion after decades of exploitation.Peripheral mineral exploration therefore has become an urgent task.Using mineral exploration around the Limu crisis mines as an example,we introduce a breakthrough method of how the three-field theory,i.e.,the material,energy and spatial fields,is applied to intensively studies areas,a history of years of mineral exploitation and complex ore-forming systems.Taking a cue from Limu regional metallogeny,we based our investigation on the metallogenic information from geology,geophysics,geochemistry and remote sensing.We conducted our study of the three-field integrated information system,associated with metallogenic prognoses from deposits,with assignments and calculations which correct and allocate synthetic metallogenic prognosis by relying on GIS.We submitted a synthetic metallogenic prognosis map of tin in Limu where we delineated three ore target areas.A breakthrough was achieved by finding about 4785 t of tin metal outside the Shiziling deposit,which has been confirmed by drilling.The successful application in Limu shows that this three-field theory is of scientific and practical importance and deserves to be extended to utilization.

Identifying the scope of the Lhasa Metropolitan Area based on a spatial field energy model

The cultivation and development of modern metropolitan areas with the aim of establishing new regional centers with competitive edge is a key objective for the new-type urbanization directions in China.The construction of the Lhasa Metropolitan Area is of great significance for the promotion of the South Asia Channel,the‘Belt and Road’initiative,the Bangladesh-China-India-Myanmar Economic Corridor,the Himalaya Economic Cooperation Zone,and for rapid development and long-term stability of the Qinghai-Tibet Plateau.This paper examines the scope of the Lhasa Metropolitan Area including Chengguanqu(Chengguan District),Doilungdeqen,Dagze,Lhunzhub,Damxung,Nyemo,Quxu,Maizhokunggar,Samzhubze Qu(Samzhubze District),Gyangze,Rinbung,Bainang,Nedong,Gonggar,and Zhanang using a spatial field energy model that combines nodality and accessibility indices and considers multiple indicators including traffic flow between cities.By combining factors such as the natural background,population agglomeration,the social economy,infrastructure construction,and the urban spatial structure of the Lhasa Metropolitan Area,it is proposed to build a bow-and-arrow-shaped urban system with‘one core,two centers,one axis,and two wings’along the valleys and the transportation trunk lines of the area.The study advocates the construction of a pure land industrial system comprising a green cultural and tourism-oriented plateau.

Study upon the Spatial Structure of Regional Eco-tourism-Based upon the Perspective of Supply and Demand and Competition Field

Along with the coming of the low-carbon era, people have paid more and more attention to the natural environment and eco-tourism will embrace a huge development. From the perspectives of the market relationship of supply-demand in economics and of field competition in physics, this paper has discussed upon the present status of the spatial structure of eco-tourism, and analyzed the relationship between supply-demand and field, in order to clarify the direction for the balance between supply and demand in the field and to guide eco-tourism to the way of sustainable development.

Selection of quantum path in high-order harmonics and isolated sub-100 attosecond generation in few-cycle spatially inhomogeneous laser fields

We theoretically study the selection of the quantum path in high-order harmonics（HHG） and isolated attosecond pulse generation from a one-dimensional（1D） model of a H_2~＋ molecule in few-cycle inhomogeneous laser fields.We show that the inhomogeneity of the laser fields play an important role in the HHG process.The cutoff of the harmonics can be extended remarkably,and the harmonic spectrum becomes smooth and has fewer modulations.We investigate the time-frequency profile of the time-dependent dipole,which shows that the short quantum path is enhanced and the long quantum path disappears in spatially inhomogeneous fields.The semi-classical three-step model is also applied to illustrate the physical mechanism of HHG.The influence of driving field carrier-envelop phase（CEP） on HHG is also discussed.By superposing a series of properly selected harmonics,an isolated attosecond pulse（IAP） with duration 53 as can be obtained by a 15-fs,1600-nm laser pulse with the parameter ε = 0.0013（e is the parameter that determines the order of inhomogeneity of the laser field）.

Effect of multiple rescattering processes on harmonic emission in spatially inhomogeneous field

The effect of multiple rescattering processes on the harmonic emission from He atom in a spatially inhomogeneous field is discussed by solving the one-dimensional time-dependent Schrtdinger equation and the classical equation of motion. By establishing the physical model of the harmonic emission in the inhomogeneous field, we discuss the related characters of the multiple rescatterings process in the harmonic generation process. It shows that the second rescattering rather than the first rescattering tends to determine the harmonic cutoff energy when the inhomogeneous parameter is larger than 0.0055. Additionally, with the classica/simulation, the underlying physical mechanism of the continuum-continuum harmonics is also revealed. Moreover, this work may provide new physical insight into the harmonic generation in an inhomogeneous field, and is beneficial to further extract the harnaonic emission from molecular systems.

Horizontal-Longitudinal Spatial Correlation of Acoustic Field with Deep Receiver in the Direct Zone in Deep Water

The horizontal-longitudinal correlation of acoustic field for the receiver near the bottom is analyzed by using nu- merical modeling. An approximate analytical solution of horizontal-longitudinal correlation coefficient is derived based on the ray method. Combining the characteristic of Lloyd＇s mirror interference pattern, the variability of acoustic field and its effect on horizontal-longitudinal spatial correlation are discussed. The theoretical pre- diction agrees well with the numerical results. Experimental results confirm the validity of analytical solution. Finally, the applicability of the analytical solution is summarized. The conclusion is beneficial for the design of bottom-moored array and the estimation of integral time for moving source localization.

Multi-threaded Fast Distance Field Computation Using Spatial Partition

This article describes three algorithms for distance field generation on triangulated model: brute force algorithm, single-threaded algorithm based on spatial partition and multi-threaded algorithm based on spatial partition. Spatial partition algorithm use equidistant network divide the bounding box into equal-sized cubes, calculates the maximum and minimum distances between the sample point and each of the small cubes,taking the minimum value from the maximum distance as the minimum distance from the sample point to the model named d1, comparing d1 with the distance from sample point to every little cube's minimum distance d2, if d1 <d2, the sample point's distance to all triangles inside this cube are greater than d1, skip this cube, otherwise, calculated the distance from the point to all the triangles intersect with the cube, then alternative d1 with the minimum value, circulate all small cubes intersect with the model. Comparing the calculation results, it can be seen that the algorithm about the multi-threaded distance field relative to the other two algorithms in computational speed is greatly improved especially for complex models.

Spatial information recognizing of ocean eddies based on virtual force field and its application

A new approach to detecting ocean eddies automatically from remote sensing imageries based on the ocean eddy＇s eigen-pattern in remote sensing imagery and ＂force field-based shape extracting method＂ is proposed. First, the analysis on extracting eddies＇ edges from remote sensing imagery using conventional edge detection arithmetic operators is performed and returns digitized vector edge data as a result. Second, attraction forces and fusion forces between edge curves were analyzed and calculated based on the vector eddy edges. Thirdly, the virtual significant spatial patterns of eddy were detected automatically using iterative repetition followed by optimized rule. Finally, the spatial form auto-detection of different types of ocean eddies was done using satellite images. The study verified that this is an effective way to identify and detect the ocean eddy with a complex form.

Available Contents and Spatial Distribution of Soil Microelements of Tobacco Fields in Liupanshui City

The contents of soil microelements can affect the growth, yield and quality of tobacco, but it is not clear of the status quo of soil microelements in tobacco fields in Liupanshui city. In this study, soil samples of the plough layers (0 - 20 cm) were collected from January to March in 2021 from 500 typical tobacco fields in Liupanshui City (100, 180 and 220 fields in Zhongshan, Shuicheng and Panzhou, respectively), the particle size composition, pH, the contents of organic matter (OM), available boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) were measured and discussed. the results show that the mean contents of B, Cu, Fe, Mn, Mo and Zn are 0.92, 2.55, 66.47, 47.26, 0.39 and 3.96 mg/kg, respectively, and among which, B, Cu and Zn are at the high grades while Fe, Mn and Mo are at the very-high grades. There are significant differences in B, Fe and Zn among the three regions, while Cu is significantly different between Zhongshan and Shuicheng, Mn is significantly different between Panzhou with Zhongshan and Shuicheng, and Mo is significantly different between Zhongshan and Panzhou. The proportions of fields deficient in microelements are relatively low, no field is Fe-deficient, and the fields deficient in Mo, B, Cu, Zn and Mn are only account for 10.40%, 9.40%, 7.40%, 2.80% and 2.00% of the total fields respectively. B-deficient fields (green and light green colors, the same below) are mainly scattered in the northwest of Zhongshan and in the north and south of Panzhou, Cu-deficient fields mainly in the middle of Shuicheng and Panzhou, Mn-deficient fields mainly in northern Zhongshan, central Shuicheng and north of Panzhou. Mo-deficient fields are mainly in the middle of Shuicheng and the middle and east of Panzhou, while Zn-deficient fields are mainly in the middle of Shuicheng and the middle and east of Panzhou. Altitude is negatively correlated with Mn (P < 0.05), pH is negatively correlated with B (P < 0.05), Fe and Mn (P < 0.01), and OM is positively correlated with Fe and Zn (P < 0.01). Sand is negatively correlated with B (P < 0.05), Mn and Mo (P < 0.01), but positively correlated with Zn (P < 0.01). Silt is positively correlated with Mo (P < 0.05);clay is positively correlated with B (P < 0.05) and Mn (P < 0.01), but negatively correlated with Zn (P < 0.01). In conclusion, most of the fields do not need to apply micro-fertilizers in Liupanshui, but the fields deficient in microelements should be considered to use the corresponding fertilizers.

Numerical modeling calculation for the spatial distribution characteristics of horizontal field transfer functions

Applying 3-dimension finite difference method, the distribution characteristics of horizontal field transfer functions for rectangular conductor have been computed, and the law of distribution for Re-part and Im-part has been given. The influences of source field period, the conductivity, the buried depth and the length of the conductor on the transfer functions were studied. The extrema of transfer functions appear at the center, the four corners and around the edges of conductor, and move with the edges. This feature demonstrates that around the edges are best places for transfer functions' observation.

基于场致二次谐波的大气压脉冲流注放电时变非均匀电场测量研究

诊断大气压脉冲流注放电空间电场是实现流注放电精准调控和揭示等离子体不稳定性机制的重要基础。基于场致二次谐波的空间电场测量方法具有非侵入式、时空分辨率高等优点。然而,流注放电时变非均匀电场对二次谐波信号产生过程的影响规律尚不完善,真实电场标定系数随流注放电不同阶段的变化规律尚不清晰。该文首先计算二次谐波信号产生规律和电场空间分布的影响;然后,基于等离子体流体模拟,分析二次谐波信号对流注放电不同阶段时变非均匀电场的敏感程度;最后,基于纳秒脉冲激光场致二次谐波电场测量平台,实验获得了重频脉冲作用下组合电极结构产生的单根负流注轴向电场演变规律,分析脉冲重复频率对空间电场的影响机制,并针对流注放电时变非均匀电场特点提出电场致二次谐波测量优化若干建议。

卷积神经网络与随机场分析桩梁基础承载力

岩土体的参数在空间上随机分布,为能更好地反应实际工程地质条件,在桩基础承载力研究中考虑土体的不确定性,并建立具有重要工程价值的承载力预测模型,将基于随机场理论的岩土参数空间变异性引入桩梁基础的研究中,采用数值方法建立桩梁基础与群桩基础的二维随机有限元模型分析承载能力,并与模型试验结果验证。随后通过卷积神经网络建立土体参数随机场图像与基础极限承载力之间的模型进行承载力预测,并基于预测模型研究不同参数的影响。结果表明:考虑土体空间变异性的基础承载力与试验结果基本吻合,随机结果均高于确定性分析;随机场下桩梁基础与群桩基础的承载力均为正态分布;采用卷积神经网络建立的基础承载力预测模型精度较高,且可以用于参数分析,基础承载力随着土体参数的增加而增加,随变异系数的增加而下降。随机条件下,桩梁基础的承载力高于群桩基础,可以充分发挥土体强度并抵御参数不确定性带来的承载力损失。

时空矢量场下人群活动聚散模式提取与分析

由于传统方法缺乏顾及人群在区域间的动态流动而无法反映人群在未来(下一时刻)的活动聚散趋势,因此,文中借助时空矢量场来建模人群活动的趋向性,通过矢量场理论中的散度算子来定量计算人群活动聚散强度,将人群活动聚散模式提取问题转化为时间序列聚类问题识别出主要聚散模式。在海口市滴滴出行数据集上进行实验,选取角度偏态系数证明了主体方向计算方法的有效性,提取出了4种主要人群活动聚散模式,并结合POI类型的分布情况对4种模式进行了语义解释,为探索人类移动性提供研究思路和方法支持。

考虑土体空间变异性的液化区埋地管道上浮反应与易损性分析

为分析可液化场地土体空间变异性对管道上浮反应的影响,以土体相对密度Dr为随机场变量,采用基于乔列斯基分解的中点法生成随机场,基于OpenSees软件进行埋地管道二维随机有限元计算,分析了土体空间变异性对管道上浮位移的随机统计特征以及管道上浮易损性的影响。结果表明:当管道上浮位移较大时,土体空间变异性条件下管道上浮位移均值小于确定性分析结果,且差距随空间变异性增强而更为显著;局部致密区间的存在一定程度上限制了管道上浮行为的发展;累积绝对速度CAV可较好表征地震动强度对管道上浮位移的影响;易损性函数的离差随土体空间变异性增强而不断增加,且均大于所对应的确定性离差,导致易损性曲线更为平缓;随机变量模型不能合理表征空间变异性对管道上浮反应的影响。

联合收割机滚动轴承故障诊断系统研究--基于声场空间分布特征

首先,介绍了联合收割机滚动轴承振动机理和故障特征,并研究了基于声场空间分布特征的故障诊断流程;然后,对联合收割机滚动轴承的声音信号采集及特征提取进行了深入研究;最后,利用神经网络算法的模式识别对联合收割机滚动轴承的故障进行诊断。验证结果表明:系统对联合收割机滚动轴承故障的综合诊断率为91.67%,系统具有可行性。

HALF-SPACE GREENS'S FUNCTION DUE TO A SPATIALLY HARMONIC LINE LOAD AND SCATTERED FIELDS IN THE FAR FIELD REGION

Half-space Green's function due to a spatially harmonic line load has been expressed as a sum of the full-space Green's functions and a 2-D integral representation of the reflected waves by the free surface of the half-space.By using the obtained half-space Green's function,an integral rep- resentation of the scattered waves by a cylindrical obstacle is then derived.Finally,by analyzing the far-zone behavior of the integrands of the integral representation.the far-field pattern of the scattered waves in a half-space obtained.

空间相干结构光场产生、传输及应用研究进展

空间相干性是光场除了振幅、相位和偏振以外的一个固有属性,它在理解光的干涉、传输、光与物质相互作用等方面起着重要作用.近年来,对空间相干性的研究已经逐渐拓展至对空间相干结构的构建及特性研究,这是因为具有特定空间相干结构分布的光场展现出了新奇的物理效应,如自聚焦、自分裂、自偏移和自整形传输特性等.这些新奇物理效应的许多潜在应用也逐渐被发现,包括在自由空间光通信中降低大气湍流的负面效应、基于空间相干结构的光学加密和鲁棒光信息传输、光学微粒俘获及操纵等.本综述系统地回顾空间相干结构光场的表征方法、理论构建和实验产生方法、在自由空间和湍流介质中的传输特性和相关应用.首先,利用非负正定条件和相干模式分解理论来表示空间相干结构光场的交叉谱密度函数;然后,讨论理论和实验上构建及产生空间相干结构光场的2种不同策略,一种是基于广义范西特-泽尼克定理,另一种是基于相干模分解理论;接下来,概述特定空间相干结构光束在自由空间和湍流大气中的新颖物理特性;最后,介绍空间相干结构光场在降低大气湍流负面效应、光学加密、复杂介质中的鲁棒光信息传输和光学微粒俘获和操纵等方面的应用.光学空间相干结构不仅为光操控提供了新的自由度,产生的空间相干结构光场在诸多领域也展现出了重要应用价值.

乡村文化传承与空间重构的逻辑辨析和重构路径

基于场域理论,从乡村文化场域的物质要素和非物质要素两方面研究建构乡村文化传承与空间重构的逻辑框架,探索在乡镇级国土空间规划中乡村文化场域的空间重构路径。以北京妙峰山镇为例,结合实际调查数据与社交媒体数据,从场域—资本—惯习的动态变化及三者的匹配关系出发,剖析妙峰山镇现存的社会、制度、经济与生态问题及其原因,从文化认同、文化创新、文化传承的视角提出乡村文化场域空间重构的路径,通过重构健康的制度场域和永续的社会场域、高效的经济场域、和谐的生态场域,探索新场所与乡土文化融合模式,推进乡村振兴及韧性发展。

基于改进YOLOv5s的面向自动驾驶场景的道路目标检测算法

在复杂道路场景中检测车辆、行人、自行车等目标时,存在因多尺度目标及部分遮挡易造成漏检及误检等情况,提出一种基于改进YOLOv5s的面向自动驾驶场景的道路目标检测算法。首先,利用深度可分离卷积替换部分普通卷积,减少模型的参数量以提升检测速度。其次,在特征融合网络中引入基于感受野模块(receptive field block,RFB)改进的RFB-s,通过模仿人类视觉感知,增强特征图的有效感受野区域,提高网络特征表达能力及对目标特征的可辨识性。最后,使用自适应空间特征融合(adaptively spatial feature fusion,ASFF)方式以提升PANet对多尺度特征融合的效果。实验结果表明,在PASCAL VOC数据集上,所提算法检测平均精度均值相较于YOLOv5s提高1.71个百分点,达到84.01%,在满足自动驾驶汽车实时性要求的前提下,在一定程度上减少目标检测时的误检及漏检情况,有效提升模型在复杂驾驶场景下的检测性能。

考虑土性参数空间变异性的珠三角软土地区土钉支护结构可靠度分析

如何定量定性描述软土土性参数空间变异性对准确确定软土土性参数和合理评价软土地区土钉支护结构稳定性至关重要。采用既有统计分析方法定量描述空间变异性通常需要大量数据,难以满足。本文基于随机场理论模拟软土土性参数空间变异性,建立了一套考虑土性空间变异性的软土地区土钉支护结构可靠度设计方法,最后以MATLAB软件包为平台进行计算程序的开发与工程实例研究。分析结果表明,本文采用随机场方法模拟软土土体固有空间变异性及其在土钉支护结构可靠度分析中的应用具有合理性与普适性。