Evolution and Development Trend Prospect of Metal Milling Equipment

The world is currently undergoing profound changes which have never happened within the past century.Global competition in the technology and industry fields is becoming increasingly fierce.The strategic competition of the major powers further focuses on the manufacturing industry.Developed countries such as the United States,Germany,and Japan have successively put forward strategic plans such as“re-industrialization”and“return of manufacturing industry”,aiming to seize the commanding heights of a new round of global high-end technology competition and expand international market share.Standing at the historic intersection of a new round of scientific and technological revolution and China's accelerated high-quality development,the“14th Five-Year Plan”clearly pointed out that intelligent manufacturing is the main development trend to promote China's manufacturing to the medium-high end of the global value chain.This reflects the importance of advanced manufacturing for national strategic layout.To better grasp the development direction of advanced manufacturing equipment,the development process and current application status of manufacturing equipment are summarized,and thereafter the characteristics of manufacturing equipment in different development stages of the manufacturing industry are analyzed.Finally,the development trend of advanced milling equipment is prospected.

Spatial Distribution Characteristics and Evolution Trends of Urban Aging Population

This paper selects Beijing, Shanghai, Guangzhou, and Wuhan as examples and builds a database based on the statistics of the ? fth and sixth national population censuses and the latest statistics of aging population collected by ministries and commissions of the Central Government and local departments, as well as by our research team from 2000 to 2010. With its data unit accurate to Jiedao~① level, it is the ? rst time to analyze the micro-level spatial distribution characteristics of the aging population in China's mega cities in comparison with research accomplishments in geography, which lays a foundation for further relevant studies and strategy formulation. The paper draws spatial distribution maps of the aging population in Beijing, Shanghai, Guangzhou, and Wuhan by Geograpic Information System(GIS), and uses Aging Degree Index and Population Gravitational Center respectively to analyze the spatial distribution characteristics and spatial evolution trends of aging population in these mega cities. The research indicates that, on the one hand, the spatial distribution of the aging population shows similar characteristics with that of developed countries when they were at the same urbanization level, especially with Japan which shares a cultural homology with China; on the other hand, it is greatly in? uenced by the distribution of af? liated residential space of large industrial sectors, enterprises, and research institutes under the early planned economic system. There are two trends: one is centrifugal spread, namely, the elderly are moving from the city center to the outside; the other is centripetal concentration, namely, the elderly who lived in the outer suburbs are moving towards the city center. These phenomena, such as centripetal concentration, suburban spread, exurban concentration, and socio-spatial differentiation of urban aging population, are driven by selective development in the city center, city function upgrading, re-hollowing of villages, and occupation and income differentiation of the elderly before retirement.

广义进化论视域下现代足球运动的发展趋势研究

现代足球运动起源于英国,它也被誉为“世界第一运动”。随着现代社会不断发展,人民群众的生活水平逐渐提高,现代足球运动逐渐发展成了极具影响力并深受人民群众欢迎的体育运动项目。该文将从广义进化论的角度评析现代足球运动的发展趋势,为现代足球的发展趋势提供理论依据。

长江口冲淤交替及变化趋势

The morphological changing trend of the Yangtze Estuary,the largest estuary of Asia,has become a focus of research in recent years.Based on a long series of topographic data from 1950 to 2015,this paper studied the erosion-deposition pattern of the entire Yangtze Estuary.An alternation between erosion and deposition was found during the past 65 years,which was in correspondence to the alternation between flood and dry periods identified by multi-year average duration days of high-level water flow(defined as discharge≥60,000 m 3/s,namely,D≥60,000)from the Yangtze River Basin.A quantitative relationship was further developed between the erosional/depositional rate of the Yangtze Estuary and the interpreting variables of yearly water discharge,D≥60,000 and yearly river sediment load,with contributing rates of 1%,59%and 40%,respectively.Mechanism behind the alternate erosion and deposition pattern was analyzed by examining residual water surface slope and the corresponding capacity of sediment transport in flood and dry periods.In flood periods,a larger discharge results in steeper slope of residual water level which permits a greater capacity of sediment transport.Therefore,more bed materials can be washed to the sea,leading to erosion of the estuary.In contrast,flatter slope of residual water level occurs in dry periods,and deposition dominates the estuarine area due to the decreased capacity of sediment transport and the increased backwater effect of flood-tide.Coastal dynamics and estuarine engineering projects alter the local morphological changes,but slightly affect the total erosional/depositional rate of the whole estuarine region.Heavy sedimentation within the Yangtze Estuary after the impoundment of the Three Gorges Dam can be attributed to the reduced occurrence frequency of flood years due to water regulation by the dam,and largely(at least 36%-52%)sourced from the sea.Deposition is still possible to occur in the Yangtze Estuary in the future,because the multi-year average D≥60,000 is unlikely to exceed the critical value of 14 days/yr which corresponds to the future equilibrium state of the Yangtze Estuary,under the water regulation of the large cascade dams in the upper Yangtze.Nevertheless,the mean depositional rate will not surpass the peak value of the past years,since the total sediment load entering the Yangtze Estuary has presented a decreasing trend.

基于时空交互视角的中国综合交通运输绿色效率动态演化趋势

It is urgent and important to explore the dynamic evolution in comprehensive transportation green efficiency(CTGE)in the context of green development.We constructed a social development index that reflects the social benefits of transportation services,and incorporated it into the comprehensive transportation efficiency evaluation framework as an expected output.Based on the panel data of 30 regions in China from 2003-2018,the CTGE in China was measured using the slacks-based measure-data envelopment analysis(SBM-DEA)model.Further,the dynamic evolution trends of CTGE were determined using the spatial Markov model and exploratory spatio-temporal data analysis(ESTDA)technique from a spatio-temporal perspective.The results showed that the CTGE shows a U-shaped change trend but with an overall low level and significant regional differences.The state transition of CTGE has a strong spatial dependence,and there exists the phenomenon of“club convergence”.Neighbourhood background has a significant impact on the CTGE transition types,and the spatial spillover effect is pronounced.The CTGE has an obvious positive correlation and spatial agglomeration characteristics.The geometric characteristics of the LISA time path show that the evolution process of local spatial structure and local spatial dependence of China’s CTGE is stable,but the integration of spatial evolution is weak.The spatio-temporal transition results of LISA indicate that the CTGE has obvious transfer inertness and has certain path-dependence and spatial locking characteristics,which will become the major difficulty in improving the CTGE.