Physical modeling of long-term dynamic characteristics of the subgrade for medium-low-speed maglevs

To investigate the dynamic characteristics and long-term dynamic stability of the new subgrade structure of medium-low-speed(MLS)maglevs,cyclic vibration tests were performed under natural and rainfall conditions,and the dynamic response of the subgrade structure was monitored.The dynamic response attenuation characteristics along the depth direction of the subgrade were compared,and the distribution characteristics of the dynamic stress on the surface of the subgrade along the longitudinal direction of the line were analyzed.The critical dynamic stress and cumulative deformation were used as indicators to evaluate the long-term dynamic stability of the subgrade.Results show that water has a certain effect on the dynamic characteristics of the subgrade,and the dynamic stress and acceleration increase with the water content.With the dowel steel structure set between the rail-bearing beams,stress concentration at the end of the loaded beam can be prevented,and the diffusion distance of the dynamic stress along the longitudinal direction increases.The dynamic stress measured in the subgrade bed range is less than 1/5 of the critical dynamic stress.The postconstruction settlement of the subgrade after similarity ratio conversion is 3.94 mm and 7.72 mm under natural and rainfall conditions,respectively,and both values are less than the 30 mm limit,indicating that the MLS maglev subgrade structure has good long-term dynamic stability.

New Developments on Existence and Uniqueness of Solutions to Some Models in Atmospheric Dynamics

This survey is concerned with the new developments on existence and uniqueness of solutions of some basic models in atmospheric dynamics, such as two-and three-dimensional quasi-geostrophic models and three-dimensional balanced model. The main aim of this paper is to introduce some results about the global and local (with respect to time) existence of solutions given by the authors in recent years, but others' important contributions and the literature on this subject are also quoted. We discuss briefly the relationships among the existence and uniqueness, physical instability and computational instability. In the appendixes, some key mathematical techniques in obtaining our results are presented, which are of vital importance to other problems in geophysical fluid dynamics as well.

A study on tourism development model with dynamic mechanism of circular economy

With the social and economic development,conflict among the shortage of resources,environmental destruction and economic development is ever more pronounced.In this context,the circular economy was gradually accepted.Guided by sustainable development concept and promoted by six external forces,tourism circular economy take tourism micro-cycle model as the core,implement in corporate and social levels,improve resource utilization efficiency,reduce tourism's adverse impacts on the surrounding environment through recycling,reducing and reusing resources,achieve economic,social and environmental development of the organic unity.

A SYSTEM DYNAMICS APPROACH FOR SUSTAINABLE DEVELOPMENT IN THE MIYUN RESERVOIR AREA, CHINA

Miyun Reservoir was designated as the water source of Beijing City in 1982. Since that time, socio economic development in Miyun Area has been slowing due to the restriction of severe environmental standards. More and more attention from the public and government has been paid to the regional sustainable development. And an effective planning for the local society management system is urgently desired. In this study, a regional sustainable development system dynamics model, named MiyunSD, is developed for supporting this planning task. MiyunSD consists of dynamic simulation models that explicitly consider information feedback that governs interactions in the system. Such models are capable of simulating the system′s behavior and predicting its developing situation of the future. For the study case, interactions among a number of system components within a time frame of fifteen years are examined dynamically. Three planning alternatives are carefully considered. The base run is based on an assumption that the existing pattern of human activities will prevail in the entire planning horizon, and the other alternatives are based on previous and present planning studies. The different alternatives will get different system′s environmental and socio economic results. Through analyzing these dynamic results, local authorities may find an optimal way to realize the objectives that the regional environment will be well protected and at the same time the economy will be rapidly developed.

Development of a global high-resolution marine dynamic environmental forecasting system

全球海洋环境安全预报保障能力的提升,是我国海洋强国战略和参与全球海洋治理的重要保障。在过去的五年中,国家海洋环境预报中心完成了没有全球保障能力到初步建立的过程,但是现有的全球海洋环境安全保障系统,无论是在精度还是深度上都不能满足需求,因此建立具有自主知识产权高分辨率的全球海洋动力环境数值预报系统迫在眉睫。因此,科技部海洋环境安全保障专项支持了‘全球高分辨率海洋动力环境数值预报系统研制’项目的立项。本项目(1)通过开展现场观测与实验室试验,研究海洋多尺度混合并优化物理参数化方案;(2)发展自主全球高分辨海洋环流、潮汐潮流、海浪及浪-潮-流耦合数值模式,发展海气耦合预报技术;(3)建立自主知识产权高分辨率的全球海洋动力环境数值预报系统,开展集成应用研发,全面提升我国自主能力与预报水平,实现中尺度现象的稳定识别和业务预报,精度达到国际同类预报产品水平。

A system dynamics approach for water resources policy analysis in arid land:a model for Manas River Basin

The Manas River Basin in Xinjiang Uygur autonomous region, similar to other arid regions, is facing water constraints which challenge decision-makers as to how to rationally allocate the available water resources to meet the demands from industries and natural ecosystems. Policies which integrate the supply and demand are needed to address the water stress issues. An object-oriented system dynamics model was developed to capture the interrelationships between water availability and increasing water demands from the growth of industries, agri- cultural production and the population through modeling the decision-making process of the water exploration ex- plicitly, in which water stress is used as a major indicator. The model is composed of four sectors： 1 ） natural surface and groundwater resources; 2） water demand; 3） the water exploitation process, including the decision to build reservoirs, canals and pumps; 4） water stress to which political and social systems respond through increasing the supply, limiting the growth or improving the water use efficiency. The model was calibrated using data from 1949 to 2009 for population growth, irrigated land area, industry output, perceived water stress, groundwater resources availability and the drying-out process of Manas River; and simulations were carried out from 2010 to 2050 on an annual time step. The comparison of results from calibration and observation showed that the model corresponds to observed behavior, and the simulated values fit the observed data and trends accurately. Sensitivity analysis showed that the model is robust to changes in model parameters related to population growth, land reclamation, pumping capacity and capital contribution to industry development capacity. Six scenarios were designed to inves- tigate the effectiveness of policy options in the area of reservoir relocation, urban water recycling, water demand control and groundwater pumping control. The simulation runs demonstrated that the technical solutions for im- proving water availability and water use efficiency are not sustainable. Acknowledging the carrying capacity of water resources and eliminating a growth-orientated value system are crucial for the sustainability of the Manas River Basin.

The dynamic coupling model and its application of urbanization and eco-environment in Hexi Corridor

This paper, taking Hexi Corridor as an example, analyzes the altemating intimidation and the dynamic evolving relation between urbanization and eco-environment in arid area of West China. We argue that the harmonious development system of the urbanization and eco-environment would go through four phases： rudimentary symbiotic phase, harmonious developmental phase, utmost increasing phase and spiral type rising phase. Throughout the four phases, the elements of the system would influence each other, coerce each other, and complete the spiral type rising process from low-grade symbiosis to high-grade harmony together. The study on Hexi Corridor shows that the urbanization level in Hexi Corridor has increased gradually from 1985 to 2003 accompanied with the fluctuations of eco-environment state. The response of eco-environment to urbanization has been evident, but lagged behind the urbanization course. At present, the harmonious development system in Hexi Corridor was in its harmonious developmental phase. However, the coupling degree has increased quickly and approached 90 yet, which is signaling that the system is about to enter the utmost increasing phase, and the ecological crisis will enter the latent period. We have found that the coupling degree can well reflect the interactive coercing and dynamic evolving situation between urbanization and eco-environment in Hexi Corridor. From the temporal change of the coupling degree, it can be concluded that urbanization sometimes needs to pay a certain cost for the damage of the eco-environment in its initial stages, but as the urbanization continues, the state of the eco-environment would be meliorated.

Spatial spillover effects of official development assistance on environmental pressure in sub-Saharan African(SSA)countries

Impoverished sub-Saharan Africa(SSA)is under increasing environmental pressure from global environmental changes.It is now generally accepted in academic circles that economic development in SSA countries can cause environmental pressure in other countries.However,there is research gap on the impact of economic assistance on environmental pressure in SSA countries and whether economic assistance causes spatial spillovers of environ-mental pressure between SSA countries.To better understand the impact of economic assistance on environmental pressures in SSA,a dynamic spatial Dubin panel model was developed.It helped us explore the spatial spillover effects of economic assistance on environmental pressures in recipient countries based on the panel data from 34 SSA countries.The results show that economic assistance had a positive stimulating effect on environmen-tal pressures of recipient countries,which means that the degree of human disturbance to the environment has deepened.Due to the regional correlation effect,neighboring countries were saddled with environmental pres-sures from the target country.Moreover,environmental pressures have time inertia,which can easily produce a snowball effect.The decomposition of effects shows that the impact of economic assistance on environmental pressures is relatively minor.Environmental pressures have spillover effects,so to deal with diffuse risks,joint regional prevention and control policies should be developed.

Predictive Mathematical and Statistical Modeling of the Dynamic Poverty Problem in Burundi: Case of an Innovative Economic Optimization System

The mathematical and statistical modeling of the problem of poverty is a major challenge given Burundi’s economic development. Innovative economic optimization systems are widely needed to face the problem of the dynamic of the poverty in Burundi. The Burundian economy shows an inflation rate of -1.5% in 2018 for the Gross Domestic Product growth real rate of 2.8% in 2016. In this research, the aim is to find a model that contributes to solving the problem of poverty in Burundi. The results of this research fill the knowledge gap in the modeling and optimization of the Burundian economic system. The aim of this model is to solve an optimization problem combining the variables of production, consumption, budget, human resources and available raw materials. Scientific modeling and optimal solving of the poverty problem show the tools for measuring poverty rate and determining various countries’ poverty levels when considering advanced knowledge. In addition, investigating the aspects of poverty will properly orient development aid to developing countries and thus, achieve their objectives of growth and the fight against poverty. This paper provides a new and innovative framework for global scientific research regarding the multiple facets of this problem. An estimate of the poverty rate allows good progress with the theory and optimization methods in measuring the poverty rate and achieving sustainable development goals. By comparing the annual food production and the required annual consumption, there is an imbalance between different types of food. Proteins, minerals and vitamins produced in Burundi are sufficient when considering their consumption as required by the entire Burundian population. This positive contribution for the latter comes from the fact that some cows, goats, fishes, ···, slaughtered in Burundi come from neighboring countries. Real production remains in deficit. The lipids, acids, calcium, fibers and carbohydrates produced in Burundi are insufficient for consumption. This negative contribution proves a Burundian food deficit. It is a decision-making indicator for the design and updating of agricultural policy and implementation programs as well as projects. Investment and economic growth are only possible when food security is mastered. The capital allocated to food investment must be revised upwards. Demographic control is also a relevant indicator to push forward Burundi among the emerging countries in 2040. Meanwhile, better understanding of the determinants of poverty by taking cultural and organizational aspects into account guides managers for poverty reduction projects and programs.

Analyses of the Temporal Development and Yield Losses due to Sheath Blight of Rice (Rhizoctonia solani AG1.1a)

Sheath blight of rice, caused by Rhizoctonia solani AG 1. 1a, has become the most important disease and caused serious yield losses in some major rice-growing regions in China in recent years. In the present study, field plot experiment was conducted to examine the relationships between disease intensity and inoculum density （ID）, the seasonal disease epidemic dynamics, and yield reductions due to disease damages. Results from the experiment demonstrated that the areas under progress curves of disease severity and those of percent rice tillers diseased were positively and closely related to the relative initial ID of the pathogen. The inoculum density-disease （IDD） relationships were simulated and the impractical linear models were obtained. Both logistic and Gompertz functions could be used to simulate the disease progress dynamics in time, but the progress curves of the disease severity were modeled better by the Gompertz than by logistic function. However, the Richards function was found to be the best in simulating the disease progress curves when a most appropriate value was chosen for the shape parameter m by using the computer software Epitimulator. Sheath blight infection decreased rice yield very significantly and a yield reduction of 40% was recorded in rice crop with the highest inoculum density. Rice yield was linearly and negatively correlated with the disease severity and the percent tillers affected. The simulated models for all these relationships were computed through executing Epitimulator software and were presented in this paper.

SIMULATING REGIONAL SYSTEMS: A SYSTEM DYNAMICS APPROACH

System dynamics is a rigorous method for qualitative description,exploration and analysis of complex systems in terms of their processes, information flows, orgaruzational boundaries and strategies, which facilitates quantitative modelling and analysis for design of system structure and the improvement of system behaviour. It can be applied to the study of a wide range of systems, and its ability to describe socio-economic characteristics and behaviour makes it suitable for the analysis of the regional development process. Three examples of System Dynamics models are reviewd to demonstrate the suitability of the method for regional analysis, and on the basis of this review the potential use of system dynamics models in China is discussed.

Research on the Development Strategy of Ningbo Transportation Port &Shipping Industry

Firstly, the development background of Ningbo Transportation Port & Shipping Industry is analyzed on a spatial scale. Based on that, the strategic goal of Ningbo transportation port Port & Shipping Industry is put forward, and strategic path analysis of strategic objectives is carried out. Finally, with the dynamic resource view, the strategic integration model of Ningbo Port & Shipping Industry is proposed.

黄河流域绿色高质量发展与绿色技术创新的动态关联分析

以黄河流域各省份2011—2020年的数据为研究样本,构建绿色高质量发展的评价指标体系,运用全局主成分—熵权法对绿色高质量发展综合指标进行测度,并采用聚类分析和面板向量自回归模型(PVAR)系统考察黄河流域绿色技术创新与绿色高质量发展水平的动态关联效应。研究结果表明:(1)2011—2020年,黄河流域各省份的绿色高质量发展水平整体呈上升趋势,不同地区的绿色高质量发展水平差异显著。(2)黄河流域的绿色技术创新与绿色高质量发展之间相互影响,各个省份绿色技术创新和绿色高质量发展水平一一对应。(3)黄河流域的绿色技术创新和绿色高质量发展之间存在明显的双向促进关系,且影响效果显著,即绿色高质量发展有助于绿色技术创新的提升,绿色技术创新能推动绿色高质量发展。

江西省农业绿色发展协同效应研究

探究江西省农业绿色发展水平的提升路径,可为农业绿色发展提供理论依据。以江西省为例,构建农业资源、生态环境和社会经济3个维度的协同发展关系,测度与评价2008—2020年江西省农业绿色发展水平现状,并通过系统动力学模型设计农业生产方式、农业科技创新、经济发展、消费习惯、政策支持5种策略下的7种情景模式对2021—2030年江西省农业绿色发展系统的影响。结果显示:在2008—2020年,江西省农业绿色发展水平先降后升,总体趋势向好,化肥农药零增长行动效果显著。在维持现有情景模式下,在2021—2030年江西省农业绿色发展水平能够进一步提升,7种情景模式均能有效促进江西省农业绿色发展水平。在各要素独立作用下,调减耕地复种指数、提高化肥利用率对江西省农业绿色发展水平的促进效果更为显著;与单要素发展相比,多要素协同发展对江西省农业绿色发展促进效果更大。为了使江西省农业绿色发展水平朝着有序方向发展,未来应构建区域多要素协同发展机制,实现农业生产生态生活全过程全方位绿色化。

“双碳”目标下黄河流域绿色技术创新效率评价及影响因素

基于“双碳”目标视角,采用超效率动态网络SBM模型测算黄河流域82市(盟)2011—2021年绿色技术创新的综合效率、科技研发效率及成果转化效率,并利用面板Tobit回归模型检验外部环境因素对三种效率的影响。结果表明:将CO_(2)排放量纳入指标体系后,中下游地区绿色技术创新综合效率得以提升,上游地区效率反而下降;黄河流域绿色技术创新综合效率呈波动上升趋势,科技研发效率起引擎作用;黄河流域绿色技术创新综合效率区域差异明显,成果转化效率差异是综合效率差异的主要来源;经济发展水平、产业结构高级化、人力资本禀赋、对外开放水平、政府支持力度和环境规制强度对三种效率的影响具有区域异质性。建议黄河流域提高绿色技术创新能力,完善创新成果转化平台,推动能源和产业结构升级。

劳动力成本上升对物流发展水平影响的时空效应

以长三角城市群26市2004-2020年的面板数据为研究样本,在测算各城市物流发展水平的基础上,借助普通面板模型、动态空间杜宾模型探究劳动力成本对物流业发展的影响。研究表明:长三角城市群物流发展水平整体呈上升趋势,由极化发展逐步转为均衡扩散发展;城市间物流发展水平表现出正向的空间自相关关系,劳动力成本对本地物流发展水平有积极的促进作用,但对邻地产生负向的空间溢出效应,异质性检验发现,发展水平低的城市更易受到劳动力成本的影响。应从物流产业空间布局、产业支持政策及劳动力成本增速等方面助力长三角地区物流业发展。

市场化水平提升对农业高质量发展的促进效应研究

农业高质量发展是我国从农业大国向农业强国迈进的必然要求,是我国经济高质量发展的应有之义。基于2011—2021年我国30个省份(未统计西藏及港澳台地区的数据)的面板数据样本,运用广义矩估计的系统GMM模型、中介效应模型和动态门槛效应模型研究市场化水平提升对农业高质量发展的影响。研究表明:市场化水平提升对农业高质量发展具有显著促进作用,但过度市场化会降低这种促进效应;无论从农业高质量发展和市场化水平的不同构成维度,还是从不同区域视角分析,市场化水平提升对农业高质量发展的影响均存在异质性;市场化水平提升可通过技术创新和产业结构调整两条中介路径对农业高质量发展产生影响;在促进农业高质量发展过程中,政府财政支农与市场化水平提升存在互补作用。为此,我国应从四个方面来提升市场化水平,促进农业高质量发展:一是要深化改革,充分发挥市场的积极作用;二是要因应施策,提升市场化推进的针对性;三是要激励创新,畅通市场化功能发挥路径;四是要优势互补,促进市场与政府协同契合。

中国新质生产力指标构建与时空演进

加快构建以新质生产力为核心的创新体系,是中国加快实现高水平科技自立自强和高质量发展的重要基础。本文从新质劳动者、新质劳动资料和新质劳动对象3个维度构建了新质生产力水平指标测度体系,采用投影寻踪模型测度了2011~2022年中国地级市层面新质生产力发展水平,并运用Dagum基尼系数法、Kernel密度估计法以及Moran's I全面探究并验证了新质生产力对不同时间维度、空间维度的动态演变特征。研究发现:新质生产力发展水平呈现稳步增长态势,相比于新质劳动者、新质劳动对象,新质劳动资料占新质生产力比重更大。各地区新质生产力发展水平存在较大差异,其中,东部地区是新质生产力发展的高地,西部地区和东北地区是新质生产力发展的洼地,并且地区内新质生产力水平也存在较大差异。同时,新质生产力的涌现与生产关系具有一定的协调性,且新质生产力能够正向促进地区的全要素生产率水平的提升。本文为如何捕捉新质生产力的动态演化特征以及生产关系如何更好的引导新质生产力能效发挥提供了参考。

On the Dynamic Model of the Development of Urban Business Center System

The static model applied nowadays in the planning of urban business center systemin China can no longer meet the requirements of modern urban construction. The authoradopted the dynamic model to study the activity pattern of the Nanjing residents who didshopping in the business center and as well the development law of the center itself, hop-ing to find out an effective planning approach for business center system.

干湿料饲喂方式下商品猪生产和健康指标模型构建与比较

【目的】精准饲养是当前生猪养殖产业的大趋势,但在实际应用中存在缺乏前期基础数据、各阶段湿料饲喂的采食量不明确等问题。本研究旨在探究干湿料饲喂猪只的生长发育规律、采食量动态模型和健康情况。【方法】选取132头平均初始体质量为(10.56±1.21)kg的商品猪,随机分为2组,每组11次重复,每次重复6头猪,2组分别饲喂干料和湿料,试验周期为120 d。通过Logistic、Gompertz和Von Bertalanffy 3种模型分析拟合干湿料饲喂猪只的生长曲线和采食量动态模型,并对干湿料饲喂猪只的健康情况进行研究。【结果】Von Bertalanffy模型拟合干料饲喂猪只生长曲线的效果最好,拟合度为0.999;Gomperz模型能更好地拟合湿料饲喂猪只的生长曲线,拟合度为0.999。Gomperz模型拟合干料饲喂猪只采食量模型的效果最好,拟合度为0.851;Von Bertalanffy模型能更好地拟合湿料饲喂猪只的采食量模型,拟合度为0.988。湿料饲喂保育仔猪的腹泻率和腹泻指数显著低于干料饲喂(P<0.05)。【结论】本研究构建了干湿料饲喂猪只的生长曲线和采食量模型,拟合效果较好;探明了干湿饲喂猪只的健康情况,为猪只的精准饲养提供了数据支撑。