Road Lateral Disconnection and Crossing Impacts in River Landscape of Lancang River Valley in Yunnan Province,China

Roads are conspicuous components in a river landscape;however,their impacts on river landscape patterns and ecological processes have not been systematically studied at the watershed scale.In this paper,the Lancang River Valley in Yunnan Province,China was selected as a case to study road lateral disconnection and crossing impacts and identify river-road network interaction.This study was primarily focused on the road impacts on soil erosion intensity and patch density by using GIS analysis at different scales and explored their distribution with terrain factors.The results showed that river density revealed spatial autocorrelation although both of the roads and rivers were distributed unevenly in the valley.The lateral road(road curvature≥1.1)proportion correlated with soil erosion intensity(p 0.01)at the small sub-basin scale.Soil erosion intensity decreased with increasing lateral road buffer width.Light erosion generally accounted for a large proportion of the erosion in the lateral road buffer zones(1.0–4.0 km),while higher class lateral roads imposed greater impacts on soil erosion than lower class roads,which primarily had a moderate erosion level.In addition,the results of road-river intersection density indicated that road crossing impacts were significantly correlated with patch density at the small sub-basin scale.Topography factor(percent of slope>25°in each sub-basin had a close relationship with the ratio of total length of road line with curvature value≥1.1 to the total number of intersections.The correlation(p 0.01)between road impacts and terrain factor revealed that topography affected the road impact distribution in the Lancang River Valley.

Hyperstatic reaction method for calculations of tunnels with horseshoe-shaped cross-section under the impact of earthquakes

Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.

Preliminary Measurement of the K-Shell Ionization Cross Sections of Ti by Positron Impact in the Low Energy Region

Measurements were performed of K-shell ionization cross sections of Ti element by 10～30 keV positron impact using the thick-target method. The effects of multiple scattering of incident positron and from bremsstrahlung photons and annihilation photons with the thick-target method are discussed with the Monte Carlo code PENELOPE. Meanwhile, the Monte Carlo method is also applied to determine the detection efficiencies of X- and γ-ray detectors. Our experimental K-shell ionization cross sections for Ti element are compared with the distorted-wave Born approximation （DWBA） theoretical predictions, and it is found that the agreement of the experimental data and theoretical values is good and this indicates that the experimental method adopted in this study is applicable.

An effective method to calculate the electron impact excitation cross sections of helium from ground state to a final channel in the whole energy region

The electron impact excitation(EIE) cross sections of an atom/ion in the whole energy region are needed in many research fields, such as astrophysics studies, inertial confinement fusion researches and so on. In the present work, an effective method to calculate the EIE cross sections of an atom/ion in the whole energy region is presented. We use the EIE cross sections of helium as an illustration example. The optical forbidden 1^(1)S–n^(1)S(n = 2–4) and optical allowed 1^(1)S–n^(1)P(n = 2–4) excitation cross sections are calculated in the whole energy region using the scheme that combines the partial wave R-matrix method and the first Born approximation. The calculated cross sections are in good agreement with the available experimental measurements. Based on these accurate cross sections of our calculation, we find that the ratios between the accurate cross sections and Born cross sections are nearly the same for different excitation final states in the same channel. According to this interesting property, a universal correction function is proposed and given to calculate the accurate EIE cross sections with the same computational efforts of the widely used Born cross sections,which should be very useful in the related application fields. The datasets presented in this paper are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00142.

Calculated cross sections for the single ionization of atoms (N, Cu, As, Se, Sn, Sb, Te, I, Pb) by electron impact

By correcting some primary parameters in the semi-classical Deutsch-Mark （DM） formula, this paper calculates the absolute single electron-impact ionization cross sections of atoms N, Cu, As, Se, Sn, Sb, Te, I and Pb from threshold to 10000 eV. The calculated cross sections are compared with available experimental data and other theoretical results. An excellent agreement was achieved between the calculated and measured cross sections for these atoms over a wide range of impact energies.

Measurement of 8～25keV electron impact K－shell ionization cross sections of Cu and Co elements

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Ab initio Calculations of Electron-Impact Excitation Cross Sections for N_2 Molecule

One of the great difficulties in understanding nitrogen plasma elementary processes is the lack of an available database of the cross-sections of electron-impact excitations and radiations. Ab initio calculations of vibrational excitation cross sections for electron collisions with nitrogen molecules in low-lying states using similarity function approach, such as a-a＇, a-w, B-B＇ and B-W transition systems, are reported here for the first time. In the meantime, the average excitation energies of neighboring levels of these systems have been calculated. In order to obtain the cross sections, accurate spectroscopic constants and transition dipole moments have been investigated. Potential energy curves and other electronic transition dipole moments for the low-lying states of N2 have been re-evaluated using complete active space self-consistent field （CASSCF） approach with aug-cc-pVqZ basis set. The calculated cross-sections could provide a database for studying the elementary processes and the properties in N2 plasma.

Theoretical analysis on fully differential cross sections for C^(6+)impact ionization of helium

Fully differential cross sections （FDCS） are calculated within a four-body model for single ionization of helium by C6＋ impact at the incident energy of 100 MeV/a.u. （atomic unit）. The results are compared with experimental data and other theoretical predictions. It is shown that our results are in very good agreement with experiment for three small momentum transfers in the scattering plane; however, some significant discrepancies are still present at the largest momentum transfer in both the scattering plane and the perpendicular plane. In actuality, the problem has not been explained by the theory during the last decade. Accordingly, the contributions of different scattering amplitudes to FDCS are analyzed. It is found that for the largest momentum transfer the cross section arising from a destructive interference of the three amplitudes is much smaller than the experimental data. However, the cross section due to the constructive interference of two scattering amplitudes between projectile-ionized electron interaction and projectile-passive electron interaction almost approaches the experimental data.

Low-Energy Multi-Impact Fracture Resistance of Cross Rolled Low Chromium Cast Semi-Steel Containing Rare Earth Grinding Ball

The low-energy multi-impact fracture resistance of the cross rolled low chromium cast semi-steel containing RE grinding balls was studied. Moreover, its damage mode was analyzed by means of metallographic examination, scanning electron microscopic examination and drop ball test. The results show that it can obtain extractive impact fracture resistance after proper heat treatment. More advantages were obtained for the ball worked in the condition of low-imp ductility act. The main reasons are the function of RE and the change in morphology of eutectic carbide network.

Properties of Cross-Rolled Low Alloy White Cast Iron Grinding Ball

The low-energy, multi-impact fracture resistance and the abrasiveness of the cross-rolled low alloy white cast iron grinding balls were studied after heat treatments at residual rolling temperature. Moreover, the means by which they are damaged and characters of the wear surface were analyzed. The results show that high resistance to impact fracture and high abrasiveness can be achieved after appropriate heat treatment at residual rolling temperature. This kind of heat treatment technology has several advantages under low impact and hard abrasive. These results are very useful for determining the optimized heat treatment technology at residual rolling temperatures.

Electron impact excitation of helium atom

A method to deal with the electron impact excitation cross sections of an atom from low to high incident energies are presented. This method combines the partial wave method and the first Born approximation(FBA), i.e., replacing the several lowest partial wave cross sections of the total cross sections within FBA by the corresponding exact partial wave cross sections. A new set of codes are developed to calculate the FBA partial wave cross sections. Using this method,the convergent e–He collision cross sections of optical-forbidden and optical-allowed transitions at low to high incident energies are obtained. The calculation results demonstrate the validity and efficiency of the method.

Electron-impact single ionizaiton for W^(4+) and W^(5+)

Electron-impact single ionization cross sections for W^q＋（q = 4–5） were calculated using the flexible atomic code（FAC） in the level-to-level distorted-wave method, considering the explicit branching ratio. The calculated cross sections are compared with the available theoretical and experiment results in detail. In the case of the contribution from the same channles as the available theoretical results, all of the calculated ionization cross sections agree with the experimental measured cross sections. But the present calculated results are larger than the experimental measurement when all channels contributions are included. Some important channels excitation autoionization（EA） contributions, such as the excitation to higher higher nl subshell from 4 f and 5[s,p], were not included into the available theoretical calculation. In general, the distorted-wave（DW） results are overestimated.

Fully differential cross sections for C^(6+) single ionization of helium

The three-Coulomb-wave （3C） model is applied to study the single ionization of helium by 2 MeV/amu C6＋ impact. Fully differential cross sections （FDCS） are calculated in the scattering plane and the results are compared with experimental data and other theoretical predictions. It is shown that the 3C results of the recoil peak are in very good agreement with experimental observations, and variation of the position of the binary peak with increasing momentum transfer also conforms better to the experimental results. Furthermore, the contributions of different scat- tering amplitudes are discussed. It turns out that the cross sections are strongly influenced by the interference of these amplitudes.

基于D-I-M协同模型的企业数字化转型财务管理风险识别研究

数字化正在重塑经济发展的轨道,成为赋能经济增长新动力。精准识别财务管理风险中的关键指标及其相互关系,对企业更好地完成数字化转型尤为关键。融合企业人力、运营、财务、环境4个基本维度,从链式传导视角构建转型背景下企业财务管理风险指标体系。通过决策试验与评价实验室(DEMATL)法,分析各影响因素之间中心度和原因度关系,并利用解释结构模型(ISM),将矩阵进一步分析得到影响因素的层级划分,归纳影响因素之间的内在指向关系,最后运用交叉影响矩阵相乘(MICMAC)法计算各因素的驱动—依赖关系以判断其属性类别。提出通过D-I-M协同分析的方法,识别财务管理风险路径,为企业进行多链融合数字化转型、规避财务管理风险提供参考。

基于CIA-ISM-BN煤矿瓦斯爆炸事故分析

为识别动态情景下煤矿瓦斯爆炸事故的影响因素,推断因素之间的因果关系,采用CIA(Cross Impact Analysis)、ISM(Interpretive Structural Model)和BN(Bayesian Network)结合的情景建模方法来构建煤矿井下瓦斯爆炸事故风险评价模型。利用CIA-ISM组合生成不同影响级别下瓦斯爆炸事故影响因素的因果层次网络,并进行情景推断和分析。将层次网络映射到BN模型中,通过概率推理量化复杂依赖关系的层次网络,确定瓦斯爆炸的主要致因和造成的损害。结果表明:(1)重视监管机制、违规生产、管理技术、员工安全教育培训、违章作业和通风环境之间的微循环,可以有效阻断事故演化路径;(2)瓦斯爆炸事故发生下,造成人员伤亡、经济损失和社会影响以及有毒有害等次灾害的概率分别为94.7%,95.0%,24.0%;(3)不健全的监管机制是导致瓦斯爆炸事故发生的根本原因。

既有交叉隧道和站台下新建地铁盾构隧道施工变形预测模型研究

在地铁建设过程中,盾构施工对既有结构的影响一直是工程施工安全和效率的关键考量因素。文章运用有限元数值模拟方法,研究广州地铁隧道A盾构施工对相邻隧道B、C和站台D的变形影响,旨在揭示新建隧道下穿既有结构时的变形规律,并预测其影响范围。研究结果表明,变形最大值位于施工轴线最近点,随着与施工位置距离的增加而减小,变形主要发生在施工平行经过期间。地表沉降呈对称分布,最大值位于隧道中部,既有隧道连接处的von-Mises应力受新建隧道开挖影响较小,应力峰值随盾构施工推进而移动,但变化幅度有限。现场监测数据与数值模拟结果高度一致,可验证该模拟方法的有效性和可靠性。文章相关研究可为地铁工程施工提供重要参考,有助于优化施工方案,提高工程的安全性和效率。

跨境合作区的尺度重构与空间响应--以横琴为例

基于尺度重构理论,搭建尺度重构对空间影响的分析框架,并以横琴为例,从领域空间、制度建构、治理结构多维度协同入手,分析尺度重构不同阶段对空间的影响,探讨尺度不协调带来的空间治理问题以及尺度再重构下横琴空间规划响应的重点。研究认为,横琴空间演化的实质是通过尺度重构的渐进式调整、治理机制的优化来实现国家战略意图。在横琴新区建设时期,其多维度尺度关系相对复杂,存在领域空间模糊化、制度空间配置失衡、治理机制失效等问题;在横琴粤澳深度合作区建设时期,尺度再次上移,对领域空间、制度建构、治理结构进行了系统调整,尝试修正“尺度陷阱”问题。因此,在新一轮尺度重构下,横琴规划应当坚持制度设计的初心,创新空间标准,创建跨界包容共享的优质生活与就业场景,探索构建多元融合的“社会特区”。

原油价格不确定性测度及其对宏观经济的非对称影响研究

有效测度原油价格不确定性并研究其对我国宏观经济的影响,具有重要的理论和现实意义。本文基于最小生成树模型,从全局视角衡量原油多元定价机制中195个影响因素的相对重要程度,并采用高维因子非预期条件波动率模型测度国际原油价格的不确定性。基于收敛交叉映射模型,本文对原油价格不确定性与宏观经济间的非线性因果关系进行识别,研究发现仅存在原油价格不确定性对固定资产投资、产出增速的单向因果关系。进一步地,在厘清原油价格不确定性对宏观经济影响机制的基础上,利用包含马尔可夫区制转移特征的向量自回归模型考察原油价格不确定性对我国宏观经济的影响,理论与实证结果均表明原油价格不确定性对我国宏观经济具有显著负向影响;在不同经济状态下,原油价格不确定性对投资、产出增速的影响具有非对称性。本研究为有效防范原油市场风险、保障能源安全和推动经济稳定增长提供了理论支持。

基于钻铤伽马信息交会的随钻中子气层识别方法

基于数值模拟方法开展钻铤次生伽马气层识别方法研究。从总非弹和俘获伽马信息中获取钻铤次生伽马产额信息,分析其在气/水层的响应差异,提出了一种基于钻铤非弹伽马和俘获伽马产额信息交会的气层识别方法,并对环境影响因素进行了分析。研究结果表明,相比于总非弹和总俘获伽马信息,钻铤的非弹和俘获伽马产额在气层识别方面具有更高的灵敏度;基于钻铤非弹伽马和俘获伽马交会的气层识别方法不但摆脱了对孔隙度信息的依赖,而且几乎不受井径和泥质含量的影响。该研究可以为改善随钻气层识别效果提供新的思路。

连续梁桥跳车冲击下车桥耦合振动响应分析

为研究车辆在不同工况下发生跳车对变截面连续梁桥动力响应的影响,文章选用1/4车辆模型,采用D’Alembert原理建立车辆振动平衡方程;基于Euler-Bernoulli梁理论将变截面连续梁划分成多个微段并进行受力分析,建立桥梁振动平衡方程,采用模态坐标法考虑振型的正交性对方程进行简化,与车辆振动方程联立得到车桥耦合振动方程,最终理论推导出跳车冲击过程中的车桥耦合振动平衡方程;利用MATLAB自编程序求解车桥耦合振动方程,得出车桥耦合动力响应。研究表明:当跳车高度不断增加时,桥梁动力响应持续加重,位移最大值逐渐增加;当不同桥跨跨中发生跳车时,跳车跨位移响应最大,距离跳车跨越远,位移响应越小。