ON MARKOV CHAINS IN SPACE-TIME RANDOM ENVIRONMENTS

In Section 1, the authors establish the models of two kinds of Markov chains in space-time random environments (MCSTRE and MCSTRE(+)) with abstract state space. In Section 2, the authors construct a MCSTRE and a MCSTRE(+) by an initial distribution Φ and a random Markov kernel (RMK) p(γ). In Section 3, the authors es-tablish several equivalence theorems on MCSTRE and MCSTRE(+). Finally, the authors give two very important examples of MCMSTRE, the random walk in spce-time random environment and the Markov br...

Model of Markov Chains in Space-Time Random Environments

A general framework of stochastic model for a Markov chain in a space-time random environment is introduced, here the environment ξ^＊：={ξ1,x∈N,x∈ X}is a random field. We study the dependence relations between the environment and the original chain, especially the ＂feedback＂. Some equivalence theorems and law of large numbers are obtained.

Research on the Construction of Aerospace Equipment Maintenance Support Chain Models

The current space launch missions are intense, and the utilization of equipment is frequent, demanding increasingly higher responsiveness and capability in maintenance and support. The aerospace equipment maintenance and support chain relies on aerospace equipment maintenance and support facilities, deploying various maintenance and support resources rationally according to specific requirements and principles, ultimately forming a unidirectional functional chain or network from the supply side to the demand side. This system helps address the “bottleneck” issue in the generation of aerospace equipment support capability and significantly improves the level of aerospace equipment maintenance and support. The model construction is a prerequisite for analyzing the formation and operation mechanism of the chain, and identifying factors affecting the efficiency and effectiveness of maintenance and support. With consideration of the particularity of aerospace equipment maintenance and support, the paper extensively investigates the construction of the aerospace equipment maintenance and support chain model by drawing on research achievements in modern supply chain and logistics theories, as well as model construction methods. It develops a structural diagram-based chain model, with symbols as key elements, and establishes an evaluation indicator system, providing insights into understanding and grasping the composition of the aerospace equipment maintenance and support chain effectively. Furthermore, it offers a reference for solving other equipment support chains’ construction and optimization problems.

Performance Evaluation System of Pig Supply Chain Based on Time-Space Perspective and Balanced Score Card(BSC)

The overall structure of live pig supply chain was constructed based on theoretical study and practical investigation, and the performance evaluation sys- tem for supply chain was studied from two perspectives of time and space and balanced score card （BSC）. From the space perspective and BSC, the performance evaluation system composed of four primary indicators （financial dimension, customer dimension, internal business dimension and innovation/learning perspective） and 26 secondary indicators. From the time perspective and BSC, the system could be divided into four stages, including formation stage, development stage, matu- rity stage and recession stage, with a total of 30 indicators.

Interaction Mechanism between Formation Process of Bank Collapse Disaster Chain and Territorial Space Utilization of Large Reservoirs

Number of reservoirs in China ranks the first in the world. Due to the complex geology, and superimposing rainfall and reservoir water fluctuation, the bank collapse chain is prone to disasters. The Yangtze River Reservoir is key geological disaster prevention area. Studying the process of reservoir disaster is significant because of the limited territorial space utilization. Scientific and technological issues, i.e., the mechanism of bank collapse disaster chain of large reservoirs, the interaction mechanism of bank collapse disaster chain and territorial space utilization, the early identification, monitoring technology and ecological prevention and control technology system of disaster chain, and the territorial space geological safety and control technology system are focused. We consider the material transformation, energy transfer and information transmission in disaster chain;adopt the survey, Space-Air-Ground integrated monitoring, theoretical analysis, numerical simulation and the multidisciplinary research methods;reveal the chain source development, evolution process of secondary and derivative disasters;explore the interaction mechanism of disaster chain and territorial space utilization;construct the system of early identification, monitoring, early warning, control and ecological preven-tion to achieve Emission Peak and Carbon Neutrality;provide theoretical and technical support for the territorial space geological safety, regulation and utilization of large reservoirs.

THE BRANCHING CHAIN WITH DRIFT IN SPACE-TIME RANDOM ENVIRONMENT(I):MODEL,MARKOV PROPERTY,MOMENTS

There are three parts in this article. In Section 1, we establish the model of branching chain with drift in space-time random environment （BCDSTRE）, i.e., the coupling of branching chain and random walk. In Section 2, we prove that any BCDSTRE must be a Markov chain in time random environment when we consider the distribution of the particles in space as a random element. In Section 3, we calculate the first-order moments and the second-order moments of BCDSTRE.

群聚传播的凝结空间生产与价值指向

互联网群聚传播生成的凝结空间强化了群聚传播多重关系缠绕的复杂机制。受到多元主体不平衡交往碰撞的影响,散漫、飘荡和漫渍的凝结空间随着互联网群聚传播的随机涨落处于永恒的流动之中,进而生产了复杂的关系链条。在以往的传播学视域中,空间始终是“缺席”或“被征服”的对象,西方空间学者虽然提出了空间生产理论,但是忽视了空间生产后伴随环境和交互作用而发生的跃变。随时随地“因事”而“凝结的空间”改变了以往空间的永恒性,借助群聚传播的时间之流对空间碎片的拼接与镶嵌,随时会发生位置漂移,没有边际亦无永久性的节点,只有永恒的空间聚合与消散,以及伴随这一过程的持续流动。凝结空间的流动习惯以多样性、复杂性、异质性来摧毁整体性和均质性。这种流动本身所具有的物质力量暗含了偶然性聚集的合力和对立性的张力,进而形成了斑斓杂陈的社会景观。在凝结空间的无限嵌套、互渗和叠置中,群聚传播的驳杂性增强了时空结构的混沌度。这些都提醒我们要重塑凝结空间中的交往理性,认识凝结空间生产的初始条件和演进规律,破除群聚传播空间生产的阻碍,实现自我超越,回归人类共通的价值本性。

CONSIDER SAINT-VENANT'S PRINCIPLE BY MEANS OF CHAIN MODEL

A precise background theory of computational mechanics is formed. Saint_Venant's principle is discussed in chain model by means of this precise theory. The classical continued fraction is developed into operator continued fraction to be the constrictive formulation of the chain model. The decay of effect of a self_equilibrated system of forces in chain model is decided by the convergence of operator continued fraction, so the reasonable part of Saint_Venant's principle is described as the convergence of operator continued fraction. In case of divergence the effect of a self_equilibrated system of forces may be non_zero at even infinite distant sections, so Saint_Venant's principle is not a common principle.

中国区域双循环价值链嵌入的分工测度与空间网络特征

面对全球经济增长动力衰退,中国经济由外循环主导的价值链结构将转向双循环格局下的价值链结构。结合全球价值链与国内价值链,构建双循环价值链的统一分析框架,并基于投入产出表的匹配及平衡,测算区域双循环间接价值链、折返价值链和区外价值链的嵌入特征,对推动新发展格局下区域经济平衡可持续发展具有重要现实意义。研究发现:区域生产存在明显的“间接偏好”和“区外偏好”。中西部地区“内循环偏好”普遍大于东部沿海地区。东部沿海地区是构成区域间价值链分工联系的核心区域,中西部区域则大多分布在分工网络的中外层。随着价值链分工方式的逐渐复杂化,区域的“东向集聚”特征愈发明显。商业、运输业和服务业在所有价值链分工中所带来的增加值均有较高份额,机械工业、交通运输设备和电气电子设备等中高技术制造业在外循环价值链中占有不小比例。要实现中国产业部门双循环价值链快速升级,应更加重视促进要素流动、破除区域壁垒;挖掘市场潜力、培育品牌企业;提升配套能力、构建自主链条。

基于电驱动的智能播补一体化马铃薯播种机设计研究

马铃薯是我国重要的粮食和经济作物,在西南丘陵山区受限于地势条件,现有马铃薯播种机在作业时均不同程度的存在株距误差大、漏播及重播率高、土壤条件适应性差的问题。为此,设计了以AT89S51单片机为运算核心的播补薯一体机,主要由漏播监测、播补薯、株距控制模块组成。其中,漏播监测模块主要由红外线发生和接收装置组成,播补薯模块主要由步进电机驱动的取种勺根据系统命令执行指定作业,株距控制模块则通过设定的株距指令控制电机的转速及修正;同时,以步进电机作为动力取代了传统的地轮驱动以减小株距误差,步进电机驱动的单链取种勺集成播补薯功能于一体。试验表明:机具作业行走速度在0.6~1m/s时,补薯成功率为73%~81%,总播种成功率为97%~98%,播种株距误差为2.52%~4.83%,整体播种性能完全满足马铃薯播种农艺要求。

电子商务发展与企业供应链效率——来自长江经济带上市公司的证据

电子商务作为数字经济时代的一种新型经济形态,对畅通经济循环、促进产业转型升级、提高企业生产经营效率方面具有重要作用。以2014-2022年长江经济带82个城市1432家沪深A股上市公司为研究样本,研究电子商务发展对企业供应链效率的影响。研究结果表明:电子商务发展能够促进企业供应链效率提高;电子商务发展直接提高了本地企业供应链效率,间接提高了周边城市企业供应链效率。异质性分析显示,电子商务发展对企业供应链效率的提高作用受企业股权性质、地理位置、所处行业的影响。研究结论有助于实现供应链健康可持续发展,并为推动长江经济带高质量发展提供参考。

铁路地质灾害勘察识别与监测预警

地质灾害对铁路建设、安全运营构成了极大威胁,“天空地”一体化综合勘察技术有效解决了地质灾害勘察识别难题。“天”基多源立体卫星遥感技术实现艰险复杂山区地质灾害的大范围精准判识,长时序InSAR与高精度GPS实现高陡岸坡的稳定性监测分析;“空”基真实感大场景、机载倾斜摄影和机载LiDAR扫描技术实现高植被覆盖区隐蔽性地质灾害判识;“地”基三维立体勘探技术获取岩土体结构、属性、参数;共同构建沟谷山地灾害链风险评价方案,为建设工程合理选址和工程设置提供依据。介绍地质灾害监测预警的方法、内容、技术和预警模型,对监测预警技术发展方向进行展望。

数字基础设施、产业链协同与全国统一大市场

数字基础设施是推动全国统一大市场建设、实现经济高质量发展的重要引擎。本文从城市间产业链协同的视角论证了数字基础设施促进全国统一大市场建设的作用机制。结果显示,数字基础设施能够促进全国统一大市场建设,对周边城市的统一大市场具有正向空间溢出效应。机制检验发现,数字基础设施通过增强城市间产业链供求信息匹配、深化产业链分工和产业链要素共享机制推动全国统一大市场建设。进一步研究发现,数字基础设施的空间溢出地理阈值大约为300km。东部地区数字基础设施对中西部地区全国统一大市场的空间溢出效应存在“极化效应”,大城市数字基础设施对中小城市全国统一大市场存在显著的正向空间溢出效应。因此,本文提出数字化转型政策要因城施策,围绕城市间产业链协同,进一步优化和完善全国统一大市场制度设计。

基于数字经济的造纸产业转型升级路径研究

数字经济是指以信息和通信技术为基础,以数据为核心,以创新为驱动,以互联网为载体,以网络效应为特征的经济形态。数字经济的发展对各行各业都有着深远的影响,其中包括了传统的造纸产业。数字经济对传统造纸产业转型升级的直接驱动效应是沿着产业链数字化转型和产业链合理空间布局展开的,并形成造纸产业空间结构的完整思路体系框架。基于此,从数字转型与各省份造纸产业链空间布局两个方面阐述数字经济影响下,传统造纸产业经济转型升级的有效路径,以突破造纸产业发展困境。

空间用高导热柔性石墨烯膜冷链性能研究

超柔性高导热冷链研究在空间载荷的红外焦平面制冷、活动性高效传热和均温热管理领域具有重要的工程价值和战略意义。提出一种新型石墨烯膜冷链构型,并对其开展热力协同设计和性能试验研究。系统地探究了冷链长度、搭接长度、端头立柱尺寸及数量等对导热带热传递的影响,同时验证了冷链长度、厚度和宽度分别对其振动传递的影响。研究结果表明:焊料填充对于冷链热导率的提升有着显著的影响。增加搭接长度、端头立柱数量和直径均能有效提高冷链热导率,而减小厚度、增加宽度和宽厚比均会增加冷链端部响应幅值。本文的研究结果可为兼具高柔性和高导热性的新一代冷链的选型与设计提供依据。

基于DEA的我国生鲜农产品冷链物流空间效率测度及提升策略研究

通过测度我国生鲜农产品冷链物流空间效率,对全国31省市生鲜农产品冷链效率差异进行分析,对提升农产品冷链物流效率提出对策建议。以全国31个省市为分析对象,采集2017—2021年面板数据,利用DEA 3.0从静态和动态两个维度对我国各省市农产品冷链物流空间效率进行测度,构建CCR模型和BCC模型分析静态效率,利用Malmquist指数分析动态效率。结果表明:我国整体冷链物流效率水平较高,但距离DEA效率前沿面还存在一定差距,各地区冷链物流效率呈现出空间差异性,技术进步变化对全要素生产力有显著推动作用。提出要提升农产品冷链物流效率各地区需结合实际情况,加大政府规划指引,促进冷链物流技术革新,培养冷链物流技术人才,提高冷链物流管理水平,促进我国农产品冷链物流协调发展。

铁路冷链运输服务产品发展研究

铁路冷链运输服务产品的发展是我国综合运输体系下的重要组成部分。在阐述冷链市场需求的基础上,从运输货物品类、基础设施配备及服务产品特性等方面重点分析Rail Express、CoolRail、Trans Cold Express等国外铁路冷链运输服务产品,并结合国外运营经验,针对国内现有服务产品提出问题分析并给出发展建议;同时合理整合冷链运输服务产品,分析成组式、整列式及混合运输服务产品特性及前景趋势,最终通过采用改良的车站作业时空网络图,实现了对冷藏集装箱的车站作业流程以及区间运行的描述,满足了冷藏集装箱全程性、时效性的要求,更好地服务铁路冷链运输发展。

基于空间双重性的全球城市功能建构

全球城市具有不同于一般城市的异质性功能,并在全球化中发挥着重大作用,这一直是全球城市研究的核心问题之一。学者们对此进行了大量探索性工作,形成了丰富的文献,但大多数研究基于单一地点空间来阐述全球城市功能的形成机理,以特征事实的现象学表述方法对此进行定义,并强调其功能发挥的控制和支配性。为此,需要对此进行反思,深刻认识全球城市功能的空间性问题,从地点与流动空间双重性来重新建构全球城市功能的形成机理、本质特征(本源性),以及全球城市的功能结构与作用方式等基本框架。

天基引导对海打击杀伤链构建方法

针对远海作战条件下传统侦察手段保障对海精确打击受限的问题,提出一种基于天基侦察信息引导对海打击的杀伤链构建方法。明确天基引导对海打击杀伤链的基本定义,设计该杀伤链的一般作战流程;建立杀伤链模型,提出打击能力和闭合时间两类性能评估指标及其综合评估方法;设计了杀伤链的构建算法,可以遍历寻找打击每一个目标的所有杀伤链,并按照性能指标评估方法将杀伤链进行排序输出。在实验验证中,基于某作战想定生成了45种杀伤链结果,验证了该方法的合理性。

我国城市区域产业链空间研究进展与方法综述

在“双循环”背景下,城市区域产业链空间组织及优化将为提升区域乃至国家的竞争力提供契机。采用Citespace软件对相关中文文献进行关键词共现和演进趋势分析。其次,梳理了城市区域产业链空间研究的主要内容及方法,研究内容主要包括产业链空间布局研究、产业链空间发展模式、产业链空间演变的动力机制、产业链空间优化对策;研究方法主要包括产业链空间特征与产业链空间布局影响因素的分析方法。最后,提出对于城市区域产业链空间研究的展望,以期为后续城市区域产业链空间组织优化研究的开展提供一定参考。