Auto-parametric resonance of a continuous-beam-bridge model under two-point periodic excitation:an experimental investigation and stability analysis

The auto-parametric resonance of a continuous-beam bridge model subjected to a two-point periodic excitation is experimentally and numerically investigated in this study.An auto-parametric resonance experiment of the test model is conducted to observe and measure the auto-parametric resonance of a continuous beam under a two-point excitation on columns.The parametric vibration equation is established for the test model using the finite-element method.The auto-parametric resonance stability of the structure is analyzed by using Newmark's method and the energy-growth exponent method.The effects of the phase difference of the two-point excitation on the stability boundaries of auto-parametric resonance are studied for the test model.Compared with the experiment,the numerical instability predictions of auto-parametric resonance are consistent with the test phenomena,and the numerical stability boundaries of auto-parametric resonance agree with the experimental ones.For a continuous beam bridge,when the ratio of multipoint excitation frequency(applied to the columns)to natural frequency of the continuous girder is approximately equal to 2,the continuous beam may undergo a strong auto-parametric resonance.Combined with the present experiment and analysis,a hypothesis of Volgograd Bridge's serpentine vibration is discussed.

Research on the Model of Coastline Demarcation and Management

The coastline demarcation and announcement models in China are outlined in this paper. The issues related to the coastline revision system, coastline zoning, coastline usage and the coastline information management are put forward. The concreted research and discussion on these issues are made which are valuable for the coastline management in our country.

Demarcation of Seabuckthorn Plantations in Three Northern Areas of China

Seabuckthorn （Hippophae rhamnoides） planting areas in the three northern areas （north, northeast and northwest） of China are divided into five planting zones： the semi-humid forest prairie climate zone for ecological and economic types of seabuckthorn plantations in the southern part of the Loess Plateau; the semi-arid steppe climate zone for similar types of plantations in the central part of the Loess Plateau; the arid desert steppe climate zone for ecological type of seabuckthorn plantations in the northern part of the Loess Plateau; the semi-arid and semi-humid steppe climate zone again for ecological and economic types of plantations in northern Hebei and western Liaoning and the cold humid steppe climate zone for economic types of plantations in the northern part of northeast China. The aim of this demarcation is to avoid a random introduction of seabuckthorn. In each of the five zones, objectives should be set and suitable seabuckthorn species, subspecies and varieties should be planted according to site conditions, seed sources and methods of tree breeding. The cultivation centers, bases, stations, or units should be established and successful models of seedling and planting methods should be encouraged. The principle of matching trees with suitable site conditions and adjusting measures to local conditions should be practiced. From a strategic viewpoint of solving ecological and economic problems of seabuckthorn development in the three northern areas, every seabuckthorn center must have its own germplasm nursery, standard plantation for popularizing, excellent seed and seedling nurseries and sufficient afforestation areas for demonstration and propaganda purposes. These measures would improve the ecological environment and promote economic and social development in the three northern areas of China.

Correlation between corneal demarcation line depth in epithelium-off and trans-epithelium accelerated corneal cross linking and keratoconus progression

AIM:To compare corneal demarcation line(DL)depth in both accelerated epithelium-off and trans-epithelium cross linking(CXL)using anterior segment optical coherence tomography(AS-OCT)and its relation to maximum keratometry(Kmax)progression in both techniques.METHODS:A prospective comparative interventional study where patients with mild to moderate keratoconus(KC)were classified into two groups:accelerated epitheliumoff and trans-epithelium CXL based on corneal pachymetry.Assessment of corneal DL depth was carried out after 3mo by AS-OCT.Kmax readings were evaluated after one year follow up using the Scheimpflug imaging system.RESULTS:Study included 74 eyes of 44 patients.Group A underwent epithelium-off CXL(41 eyes),while Group B underwent trans-epithelium CXL(33 eyes).At 3mo follow up,mean corneal DL depth in Group A was 219.9±58.4μm while in Group B was 127.2±7.8μm(P<0.05).The mean Kmaxchangedfrom51.9±3.9to51.3±4.2dioptersin Group A and from 53.1±4.1 to 53.6±5 diopters in Group B with insignificant difference in Kmax changes in either group(P>0.05).In addition,no significant change in corneal pachymetry was found in both groups(meanchange at 1y:6.4±4.7 and-10.1±2.3μm in Groups A and B respectively).CONCLUSION:Despite a significantly deeper corneal DL depth created by accelerated epithelium-off CXL technique compared to accelerated trans-epithelium CXL,there is no significant impact on keratoconus progression.

Poor rich demarcation of Matthew effect on scale-free systems and its application

In a scale-free network, only a minority of nodes are connected very often, while the majority of nodes are connected rarely. However, what is the ratio of minority nodes to majority nodes resulting from the Matthew effect？ In this paper, based on a simple preferential random model, the poor-rich demarcation points are found to vary in a limited range, and form a poor-rich demarcation interval that approximates to k/m E [3,4]. As a result, the （cumulative） degree distribution of a scale-free network can be divided into three intervals： the poor interval, the demarcation interval and the rich interval. The inequality of the degree distribution in each interval is measured. Finally, the Matthew effect is applied to the ABC analysis of project management.

Distribution area demarcation for logistic centers under geographical information system decision support system

Demarcating distribution area of goods is often guided by the rule of thumb by business proprietors. However, this method seems to be unsuitable when the demand points increase to a certain large extent. The present work attempted to convert the problem of distribution area demarcation into a localized problem of warehouseing and networking, and tried to establish district-based planning mode based on location based heuristic (LBH). Two methods were used in this study: 1) the manual method to construct the mathematical model and conduct simulation; 2) the automatic method using TransCAD software of geographical information system (GIS) for simulation. By comparing the effects of the two methods, the research provides theoretical support for business proprietors to demarcate the distribution area rationally with the application of GIS system. The results show that GIS has very good graphics construction function to replace complex text, and the automatic demarcating mode with human-machine interaction provides a good business decision-making support.

The Dilemma of Scientific Demarcation and Its Possible Approach

From logicism to historicism,philosophers of science have put forward different standards of scientific demarcation according to their own scientific views.However,these standards encounter problems either in theory or in practice,and then fall into difficulties,thus moving towards relativism.Philosophy of scientific practice has reversed the previous image of science with scientific practice and pointed out the temporality,dynamics and locality of science.Therefore,the scientific boundary under this approach also has the above characteristics.Besides,the scientific boundary constructed by the scientific image is developmental and features temporary stability and effectiveness.Scientific demarcation is not a purely epistemological problem,but also a practical one.

Stochastic Programming for Hub Energy Management Considering Uncertainty Using Two-Point Estimate Method and Optimization Algorithm

To maximize energy profit with the participation of electricity,natural gas,and district heating networks in the day-ahead market,stochastic scheduling of energy hubs taking into account the uncertainty of photovoltaic and wind resources,has been carried out.This has been done using a new meta-heuristic algorithm,improved artificial rabbits optimization(IARO).In this study,the uncertainty of solar and wind energy sources is modeled using Hang’s two-point estimating method(TPEM).The IARO algorithm is applied to calculate the best capacity of hub energy equipment,such as solar and wind renewable energy sources,combined heat and power(CHP)systems,steamboilers,energy storage,and electric cars in the day-aheadmarket.The standard ARO algorithmis developed to mimic the foraging behavior of rabbits,and in this work,the algorithm’s effectiveness in avoiding premature convergence is improved by using the dystudynamic inertia weight technique.The proposed IARO-based scheduling framework’s performance is evaluated against that of traditional ARO,particle swarm optimization(PSO),and salp swarm algorithm(SSA).The findings show that,in comparison to previous approaches,the suggested meta-heuristic scheduling framework based on the IARO has increased energy profit in day-ahead electricity,gas,and heating markets by satisfying the operational and energy hub limitations.Additionally,the results show that TPEM approach dependability consideration decreased hub energy’s profit by 8.995%as compared to deterministic planning.

中国儿童文学知识生产的机制与路径

中国儿童文学的现代化得益于其知识体系的建构。中国儿童文学含纳的知识主要体现在“中国”、“儿童”与“文学”上。三者的知识意涵及权力关系衍生了新的文学框架。从发生学的机理看,现代概念向现代知识的转换开启了中国儿童文学学科化的自主道路。对儿童文学元概念的界定是确立知识范畴、依据和方法的重要途径,这要求突破描述性概念的知识单面化,向着结构与系统的知识场域跃升。学科界分与跨学科构成了知识生产的完整序列,学科界分是跨学科的理论前提,跨学科又促发了新一轮关于学科界分的思考。中国儿童文学与现当代文学的界分要遵循“一体化”与“主体性”辩证的逻辑,在文学史建制的基础上推动百年新文学知识体系的现代化发展。

低温共烧陶瓷激光测厚系统设计与误差分析

基于提升低温共烧陶瓷(low temperature co-fired ceramic,LTCC)厚度的检测精度、测量效率和可溯源性的需求,设计一套LTCC激光测厚系统。针对测量精度难以满足需求的问题,对存在误差进行分析,采用厚度测量用调整夹具消除同轴度误差和线性度误差,优化设计结构降低倾角误差,循环传感器标定消除重复度误差,通过数据优化和滤波处理降低机械振动误差,提高了系统测量精度。与实际产品厚度数据对比,最终精度误差≤5μm,符合产品的应用要求,具有广阔的应用市场。

大范围生态保护红线定标布局方法

生态保护红线勘界定标是生态保护红线划定落实之后的又一项重要工作,是常态化监管的基础和前提。当前,生态保护红线勘界定标处于摸索试点阶段,国家层面缺乏具体指导细则,省市作为生态保护红线勘界定标工作的责任主体,只能结合实地因地制宜开展,缺乏系统性、标准性。定标布局是勘界定标的关键环节,主要解决生态保护红线区域内界桩和标识牌的数量确定、拟埋设位置选择等问题。本文提出一种大范围生态保护红线定标布局方法,先将生态保护红线区域按一定尺度划分为格网单元,筛选出涉及生态保护红线边界的格网单元,再引入行政区域、人口数量、道路交通、地形类别等特征因子构建度量模型,进一步开展度量特征计算,根据特征阈值最终选定格网单元,并以最终选定的格网单元作为定标布局方案,指导界桩和标识牌数量设定及埋设点位选址。以重庆市为例开展大范围生态保护红线定标布局应用,为重庆全市域生态保护红线勘界定标工作提供了第一手资料,同时,验证了本文方法在指导省市实施生态保护红线定标布局的科学性和实用性。

基于休止角试验的颗粒钾肥离散元模型参数标定

为了获取颗粒钾肥的离散元模型参数,对一种颗粒钾肥测量三轴尺寸、质量,通过查阅文献确定离散元仿真参数的取值范围,并通过无底圆筒堆积物理试验,获得颗粒钾肥的休止角。采用EDEM软件建立颗粒钾肥仿真模型,通过试验设计,以期获得不同参数组合下的休止角仿真试验结果。通过Design Expert软件内部的Plackett-Burman功能,对仿真所需要的8个关键参数进行显著性测评,发现钾肥-钾肥静摩擦因数以及钾肥-钾肥滚动摩擦因数对休止角的角度有显著影响;通过最陡爬坡试验进一步确定这两个参数的取值范围,其余6个参数由于显著性较小全部取中值。在此基础上,根据Box-Behnken试验结果建立了休止角与显著性参数的二阶回归模型,并对模型进行了优化,最终确定参数的取值为:钾肥泊松比为0.25,钾肥剪切模量为7.3×10^(7),钾肥-钾肥恢复系数为0.35,钾肥-钢板恢复系数为0.25,钾肥-钾肥静摩擦因数为0.4,钾肥-钢板静摩擦因数为0.3、钾肥-钾肥滚动摩擦因数为0.2、钾肥-钢板滚动摩擦因数为0.245。采用上述参数组合,进行休止角仿真试验,对仿真休止角与物理试验休止角结果作对比验证,通过T检验发现二者没有显著差异(t<t_(0.05/2))。由此表明,采用响应面优化标定颗粒钾肥离散元模型关键参数可行,标定的参数可为颗粒钾肥离散元仿真提供参考。

高速铁路信号系统碳排放边界划分及分析

准确量化高速铁路信号系统的碳排放量,对高速铁路碳排放核算及低碳化发展有重要意义。本文提出在计算其碳排放时需要综合考虑信号系统相关关联活动的思路,并划分信号系统的碳排放边界;提出基于能源消耗的信号系统碳排放计算方法,进一步利用碳流理论分析计算信号系统内各设备的相关碳流指标;最后以甘肃省兰州西高铁站为例进行分析,验证本文所提方法的可行性和有效性。结果显示,控制及监测系统的碳排放主要与电力碳排放因子有关,维护保养电码化设备所产生的碳排放平均仅有0.12 kgCO_(2)·d^(-1);信号系统各设备间的平均支路碳流密度为0.0076 kgCO_(2)·kWh^(-1),各设备的节点碳势与支路碳流密度相等。结论表明,各子系统的碳排放量主要和其能耗类型有关,电能消耗引起的间接碳排放是信号系统碳排放的主要组成部分,信号系统相关活动引起的直接碳排放与一次能源消耗成正比。

临近空间竞争格局与应对策略

临近空间是空气空间和外层空间之间的过渡区域,其独特的战略价值和广阔的应用前景引起各国竞相发展。本文阐述了临近空间的特点及国际社会对临近空间划分界定的主张,重点分析了美国、欧盟、俄罗斯等主要国家和地区临近空间领域的发展态势及其竞争力,剖析了我国临近空间发展面临的风险和挑战,包括国家安全风险、飞行安全风险、技术迟滞风险、技术突袭风险,飞行器技术挑战、经济可持续挑战、政策法规挑战等,并提出了我国在临近空间领域应对国际竞争、全面发展的对策建议。研究建议,加强临近空间防御技术研究、加快制定飞行安全标准规定、破解飞行器研发应用卡滞点、加大颠覆性创新技术攻关应用等,力争我国在全球临近空间发展中处于有利地位。

论破产欺诈行为刑民界分的认定标准

破产欺诈行为既可能构成民事违法也可能构成刑事犯罪,破产欺诈行为的刑民界分是指以何种标准将破产欺诈行为中构成虚假破产罪、妨害清算罪的行为挑选出来以两罪论处。司法实务中因对虚假破产罪与妨害清算罪做了不合理的限制解释导致对破产欺诈行为做出了不合理的刑民界分,破产主体、破产欺诈行为所处何种程序不应当成为刑民界分时的筛选标准;破产欺诈行为的刑民界分除了数额、情节等可作为筛选标准外,可从破产欺诈的行为类型上进行筛选,也可从破产欺诈行为与破产状态的因果关系上进行筛选。

GIS在农业资源管理项目中的应用分析

以粮食生产功能区和重要农产品生产保护区划定管理项目为依托,建立农业资源管理数据库,进而为提高农业资源优化配置和合理开发利用服务。以项目业务流程为主线,分析GIS在生产工序中发挥的作用和遇到的问题,总结问题并提出解决建议,对GIS在行政审批和数据共享方面应用进行展望,为农业资源管理和信息化建设提供参考和借鉴。

基于Norton-Bailey模型的高温设备316H不锈钢蠕变本构参数标定方法研究

基于Norton-Bailey模型,开展316H不锈钢蠕变本构方程参数的第1、2阶段分阶段标定方法研究。为了合理确定两个阶段的分界点时间,提出一种用于阶段划分的数据处理方法,该方法通过给定一组应力相关的分界点时间初值,分阶段分别进行蠕变参数拟合标定,使用最佳平方逼近方法修正分界点时间,获取最佳蠕变参数。以ASME BPVC.Ⅲ.5—2021提供的316H不锈钢蠕变数据作为基础数据,拟合500、550℃时的Norton-Bailey蠕变本构方程参数,结果显示,拟合所得曲线与原数据一致性较好。

关于两个两点Witten-Kontsevich关联子公式等价的一个注记

We prove the equivalence between two explicit expressions for two-point Witten-Kontsevich correlators obtained by Bertola-Dubrovin-Yang and by Zograf, respectively.

Global Calibration Method for Monocular Multi-View System Using Rotational Dual-Target

To make the problems of existing high requirements of calibration tools, complex global calibration process addressed for monocular multi-view visual measurement system during measurement, in the paper, a global calibration method is proposed for the geometric properties of rotational correlation motion and the absolute orientation of the field of view without over lap. Firstly, a dual-camera system is constructed for photographing and collecting the rotating image sequence of two flat targets rigidly connected by a long rod at different positions, and based on the known parameters, such as, target feature image, world coordinates, camera internal parameters and so on, then the global PnP optimization method is used to solve the rotation axis and the reference point at different positions;Then, the absolute orientation matrix is constructed based on the parameters of rotation axis, reference point and connecting rod length obtained by this method. In the end, the singular value decomposition method is used to find the optimal rotation matrix, and then get the translation matrix. It’s shown based on simulation and actual tests that in comparison with the existing methods, the maximum attitude and pose errors is 0.0083˚ and 0.3657 mm, respectively, which improves the accuracy by 27.8% and 24.4%, respectively. The calibration device in this paper is simple, and there are no parallel, vertical and coplanar requirements between multiple rotating positions. At the same time, in view of the calibration accuracy, the accuracy requirements of most application scenarios can be met.

水利“一张图”在水利工程划界管理中的应用

本文从解决水利工程划界工作中存在的水利系统内部数据融合性不强、水利系统与其他外部系统间业务融合度不高、水利系统辅助决策能力偏弱等问题出发,提出一种以水利“一张图”为基础、以空间地理信息等关键技术为支撑的水利工程划界方法,通过厘清设备设施权属、管理范围、保护范围和工程范围等内容,实现对水利工程划界工作的关键信息归集、异构系统互联互通、区域范围对比等功能,验证了方法的有效性,为解决同类问题提供了一种新思路。