ABSTRACT
Ensuring national food security is an eternal topic. We unified six categories of food with calorie content including grain, oil, sugar, fruits and vegetables, animal husbandry, and aquatic products on the basis of provincial-level data, and we dynamically evaluated caloric production capacity and the supply-demand equilibrium under the increase in feed-grain consumption as well as the food losses and waste in China from 1978 to 2020 at four different levels. The results show that: (1) From the perspective of food production, the total national calorie production showed a linear growth trend, with a growth rate of 31.7 × 1012 kcal/year, of which the proportion of grain crops has always exceeded 60%. Most provinces showed significant increasing trends in food calorific production, except for Beijing, Shanghai, and Zhejiang, which showed slightly decreasing trends. The distribution pattern of food calories and their growth rate were high in the east and low in the west. (2) From the perspective of the food supply-demand equilibrium, the national food calorie supply has been in surplus since 1992, but significant spatial heterogeneity is detected, with the Main Marketing Region changing from a tight balance to a short surplus, North China always remaining in calorie shortage, and 15 provinces still presenting supply and demand gaps up to 2020, necessitating the establishment of a more efficient and faster flow and trade system. (3) The national food caloric center has shifted 204.67 km to the northeast, and the population center has shifted to the southwest. The reverse migration of the centers of food supply and demand will further aggravate the pressure on water and soil resources and cause higher requirements for ensuring the circulation and trade system of food supply. The results are of great significance for the timely adjustment of agricultural development policies, making rational use of natural advantages and ensuring China's food security and sustainable agricultural development.
ABSTRACT
In the context of the complex international situation and novel Coronavirus pandemic, the issue of food security in China has become more important. Shaanxi province is an important agricultural production base in northwest China. It is of great significance to explore and analyze the spatial-temporal evolution characteristics and driving factors of cultivated land pressure in Shaanxi Province. This study is based on the number and distribution situation of cultivated land from 1995 to 2019 in Shaanxi, the minimum area of cultivated land per capita Sminand cultivated land pressure index P measure, to integrate the traditional difference index, establish the overall differentiation measure index of GDI, reference gravity mobile model and overall differentiation measure index of GDI describe the spatial and temporal variation characteristics of cultivated land pressure in the area. The driving factors of cultivated land pressure change were analyzed and discussed by using grey correlation analysis method. The results showed that the cultivated land area in Shaanxi province decreased firstly and then increased from 1995 to 2019. The cultivated land pressure index showed a downward trend, and remained at the level of "warning pressure" for a long time, with a small variation range. The center of cultivated land pressure in Shaanxi province was located in Guanzhong area, and moved northwestward first, then southward year by year. The spatial differentiation of cultivated land pressure in Shaanxi province was not obvious before 2003, and the state was relatively stable, and the differentiation pattern became more and more obvious after 2003. Frost-free period, precipitation, grain yield per unit, fertilizer use, income of rural residents, income of urban residents, economic development level and industrial level had significant effects on cultivated land pressure in Shaanxi Province from 1995 to 2019. © 2022 Journal of Chinese Agricultural Mechanization Editorial Office. All rights reserved.
ABSTRACT
It is the cornerstone of precise and scientific prevention and control to understand the temporal evolution and spatial pattern of the COVID-19 epidemic. Based on the county-level COVID-19 case of the United States from January 22, 2020 to October 8, 2021, we explored and analyzed the epidemic by using time series analysis, spatial autocorrelation analysis and gravity center trajectory analysis. The results show that: (1) the epidemic in the United States experienced four stages of low incidence, growth, peak and rebound with June 15, September 30 and October 1, 2020 as the cut-off points. (2) The global Moran index experienced a process of 'increase-decrease-increase-stability', with the maximum value exceeding 0.6, indicating that the epidemic has obvious spatial aggregation;the epidemic is dominated by high-high clusters (over 150 counties) and low-low clusters (over 500 counties), presenting a pattern of 'three cores and multiple islands' and 'north-south belt'. (3) In 60% of states, the trajectory of the epidemic center of gravity is near-linear type. The epidemic hotspots in these states were relatively stable over time. In more than half of the states, the curve of the moving distance of the epidemic center of gravity is exponential. These states experienced a very rapid epidemic. This study is expected to provide a reference for evaluating the effectiveness of epidemic prevention measures and determining targeted epidemic prevention measures, as well as accumulate experience for future research on the spread of different infectious diseases in different regions. © 2022 IEEE.
ABSTRACT
Scientific and moderate exercise is an effective remedy to boost the immune system and minimize the risk of infection in coronavirus disease 2019 (COVID-19) epidemic period. In this context, social media platforms play an essential role in communicating scientific fitness at home. Based on the integrated analysis of communication, physical geography, and health geography, this article takes short fitness-based videos on TikTok as the research object and comprehensively uses text analysis, mathematical statistics, and spatial analysis to reveal the characteristics of communication elements, fitness preferences, and the spatiotemporal evolution of these short videos, and to explore the communication mechanism and optimization path of short videos. The results show that: (1) the communication information focusing on "fighting against the epidemic and keeping fit at home" is made into short videos by female youth. Through the communication channels mainly composed of texts, pictures, and audio, the communication subjects carry out multilevel interactive communication with the communication objects;(2) fitness preferences are mainly composed of dances, unarmed fitness, and fitness with equipment;(3) from the perspective of time, taking February 20 as the node, the daily number of released short videos shows a trend of "increase before decrease";from the perspective of space, the distribution is significantly unbalanced across provinces, and the direction is not apparent;and (4) this article explores the communication mechanism and targeted optimization countermeasures of short fitness-based videos on TikTok in China's COVID-19 epidemic period.
ABSTRACT
The spatio-temporal evolution of major public infectious epidemics during government's strict control period in prefecture-level city can effectively reflect china's comprehensive emergency prevention and control capabilities. Based on statistical data including number of active cases, total confirmed, deaths of COVID-19 in 312 cities in China from January 24 to March 5, 2020, this paper uses methods including exploratory spatial data analysis, optimized hot spot analysis, spatial Markov chain, spatial panel data model to analyze spatio-temporal evolution characteristics of COVID-19 epidemic in China under government's strict control.The study found that: (1) The number of active cases of COVID-19 in China experienced characteristics of "rapid growth and diffusion, basic control, gradual decline, and complete control in some areas" and reached its peak on February 17, with an average daily growth rate of 17.5% during rising period and an average daily decline rate of 5.1% during falling period, and the epidemic change characteristics of most cities are similar to Nationwide's situation;(2) The high population mobility during Spring Festival transportation period is main reason for rapid expansion of epidemic. The Baidu's migration scale index for the 14 days prior to Wuhan closure was significantly correlated with total confirmed cases of COVID-19 in some cities;(3) The method called optimized hot spot analysis has identified that spatial distribution of hot spots of epidemic is stable and mainly distributed in 36 cities with Wuhan as the center and a radius of about 350 kilometers, while no statistically significant cold spot cities were identified;(4) The results of Markov chain transfer probability matrix analysis of active cased of COVID-19 in 312 cities show that various types are more stable and the probability of maintaining original type is greater than 0.85. The average probability of downward transfer is significantly higher than the probability of upward transfer. The probability of each type of transition changes significantly under the influence of different spatial lag types;(5) The estimation results of the spatial panel data model show that the number of active cases of COVID-19 in cites has spatial-temporal autocorrelation. This paper analyzed spatio-temporal evolution characteristics of COVID-19 epidemic during government's strict control period at prefecture-level city level from multiple perspectives, the focus of COVID-19 prevention and control is to reduce its spatio-temporal autocorrelation effects, this study provides a decision-making reference for government's current and future response to major public infectious epidemics. 2021, Science Press. All right reserved.