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   Science & Technology Review
2023, Vol.41, No. 20
28 October 2023

Reviews

Foreword
Papers
Special to S&T Review
Suggestions
Exclusive:Food Security
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Science & Technology Review. 2023, 41 (20): 0-0.
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Abstract ( 100 )
Foreword

Science & Technology Review. 2023, 41 (20): 1-1.
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Abstract ( 112 )
Special to S&T Review

Promoting agricultural engineering to ensure food security in China

WEI Xiuju, ZHU Ming, LIAO Yan
Science & Technology Review. 2023, 41 (20): 5-19. ;  doi: 10.3981/j.issn. 1000-7857.2023.20.001
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Abstract ( 96 )
In order to better play the role of agricultural engineering in ensuring food security, this article analyzes the different contributions of various branches of agricultural engineering, and proposes key directions for the development of agricultural engineering in China according to the constraints of resources, environment, and ecology faced by food production in China. The contributions of various branches of agricultural engineering in ensuring food security are as follows: agricultural mechanization improves labor production efficiency and ensures the planting area of grain; agricultural soil and water engineering ensures the safety of soil and water resources; land consolidation engineering ensures the quantity and quality of cultivated land; agricultural biological environmental engineering implements intensive production without competing with grain for land; rural energy and environmental engineering reduces environmental pollution; agricultural product processing engineering reduces grain loss and seed processing increases grain production. The key development directions of agricultural engineering technology are as follows: playing a comprehensive and collaborative role in promoting the construction of high standard farmland, improving the level of agricultural mechanization and informatization, improving agricultural product processing technology, promoting seed industry engineering, developing ecological agricultural engineering, and improving farmland infrastructure construction. Food security is a comprehensive project, and the coordinated implementation of agricultural engineering technology can provide technical support and necessary guarantees for China's food security.
Suggestions

Problems and suggestions of Anti-food Waste Law of the People's Republic of China at the present stage

CHENG Shengkui, WANG Lingen, WU Liang, ZHANG Dan
Science & Technology Review. 2023, 41 (20): 20-24. ;  doi: 10.3981/j.issn.1000-7857.2023.20.002
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Abstract ( 59 )
Food security is a major issue in state governance. Carrying out work has significance for ensuring national food security. The promulgation and implementation of the "Anti-food Waste Law of the People's Republic of China" marks that the anti-food waste of China has shifted from moral constraints to legal governance. However, there are still problems such as the need for further clarification of work rights and responsibilities, the lack of a standard system, the basic data statistics system has not been established, and the scientific research support needs to be strengthened during the implementation of this law. Relevant departments should take the following measures to guide and standardize the "Anti-Food Waste Law": strengthening relevant scientific research; strengthening the monitoring and assessment of food waste; implementing the relevant rules; strengthening the linkage between relevant departments; strengthening publicity and education against food waste; and strengthening the implementation and supervision of laws and other measures.
Exclusive:Food Security

The achievements of China's agricultural science and technology innovation and development as socialism with Chinese characteristics for a new era

WANG Xiaojun, MAO Shiping
Science & Technology Review. 2023, 41 (20): 25-31. ;  doi: 10.3981/j. issn. 1000-7857.2023.20.003
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Abstract ( 57 )
Entering the new era of socialism with Chinese characteristics, the strategic position of agricultural science and technology innovation in the development of“agriculture, rural areas and farmers”has been continuously improved, and its supporting and leading role in the development of“agriculture, rural areas and farmers”has been continuously enhanced, which has made important contributions to ensuring national food security and winning the fight against poverty. In the future, agricultural scientific and technological innovation will not only face multiple challenges,such as the increase of international uncertain factors, the prominent domestic agricultural structural contradictions and enhanced resource and environmental constraints, but also face enormous development opportunities brought by the new round of scientific and technological revolution. It is suggested that the investment and support policies for scientific and technological innovation should be strengthened in eight areas: biological breeding, cultivated land conservation, agricultural machinery equipment and intelligence, smart agriculture, digital agriculture, green ecology, new food manufacturing, and prevention and control of major risks and disasters.

Regional difference and distribution dynamic evolution of virtual cultivated land resources flow in China's grain trade

CAO Chong
Science & Technology Review. 2023, 41 (20): 32-43. ;  doi: 10.3981/j.issn.1000-7857.2023.20.004
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Abstract ( 79 )
Taking the grain-related data of 30 provinces in China from 2002 to 2020 as the research sample, based on the estimation of the flow of virtual cultivated land resources in grain trade, the Dagum Gini coefficient and its decomposition method, Kernel density estimation method and Markov chain analysis method were used to empirically investigate the regional differences and distribution dynamic evolution trend of virtual cultivated land resource flow in China's grain trade. The results show that: (1) the net import of virtual arable land resources in China's grain trade is on the rise, but the development is unbalanced between regions, showing the characteristics of "eastern> western > central"; (2) Inter-regional differences are the main source of regional differences in the net import of virtual arable land resources in China's grain trade, with a contribution share between 60%~70%, and the overall differences between the whole country and the three major regions are large, showing a trend of "rising first and then falling"; (3) The center development trend of net imports of virtual arable land resources in grain trade in the whole country and the three major regions gradually shifted to the right, except for the central region, the phenomenon of right tailing is significant, and the polarization phenomenon is alleviated; (4) When the spatial conditions are not considered, the net import of virtual cultivated land resources is more sustainable, and there will be no state transfer between provinces, but the trend to a high level is obvious. Therefore, it is necessary to clearly understand the spatial imbalance of the net import of virtual cultivated land resources in grain trade, and dynamically adjust the grain import and export trade policy, and at the same time pay attention to avoiding the negative impact of excessive import of virtual cultivated land resources in grain trade on the domestic market.

Spatio-temporal changes of cultivated land non-grain conversion and the regional differences of its influence on economic growth in sichuan province in recent 20 years

CHEN Lei
Science & Technology Review. 2023, 41 (20): 44-54. ;  doi: 10.3981/j.issn.1000-7857.2023.20.005
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Abstract ( 72 )
In this paper, the spatial-temporal characteristics of non-grain cultivated land in Sichuan province from 2000 to 2019 were analyzed by using quantitative model, and the influence of non-grain cultivated land on economic growth was discussed by using Theil index decomposition method. The results showed that: In terms of temporal characteristics, both the non-grain area and the non-grain rate of cultivated land in Sichuan province showed a fluctuating increase in time series, which increased first, then decreased before 2010 and then increased after 2010, and there was a negative correlation between the nongrain conversion of cultivated land and the proportion of cultivated area of food crops in the five economic zones. In terms of spatial characteristics, the non-grain area of 21 cities and prefectures was less in northwest and more in southeast, but the non-grain rate was higher in northwest and lower in southeast, and the spatial difference of the five economic zones was obvious, and the changes of the non-grain area and the non-grain rate of cultivated land were not synchronous. The non-grain area of cultivated land in Sichuan province and its five economic zones was correlated with GDP, and the non-grain conversion of cultivated land had non-absoluteness to regional GDP growth; Although the overall difference of the impact of non-grain cultivation on economic growth had decreased, the regional and spatial difference was significant, and the regional contribution difference was the source of the overall difference of the whole province, which was affected by the regional difference of economic development. And the countermeasures and suggestions of strengthening the control of the use of cultivated land, strengthening the coordinated management of departments, perfecting the compensation system of cultivated land, and strengthening the publicity of cultivated land protection were put forward.

The concept, scientific issues and prospect of the groundwater benefit zone in the saline farmland

ZHAO Ying
Science & Technology Review. 2023, 41 (20): 55-63. ;  doi: 10.3981/j.issn.1000-7857.2023.20.006
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Abstract ( 58 )
This paper focuses on the processes of water and salt movements in the groundwater-soil-plant-atmosphere continuum (GSPAC) system. First, it analyzes the key driving factors and mutual feedback mechanisms of the groundwater hydrological process and farmland ecosystem and proposes a new conception of groundwater benefit zone (GBZ). Secondly, it elaborates on the formation mechanisms of the groundwater benefit zone and the model development for simulation of the GBZ. Finally, based on the saline farmland water-salt coupling transport mechanism, scale effects, quantitative model of GBZ, and technical parameters of regional groundwater and salt regulation and control, the scientific issues and challenges related to the research framework of GBZ are prospected.

Influence of land consolidation on profit of planting industry in dry hot valley in China

WANG Bao, ZHANG Yanyu, ZHANG Jiansheng, GUO Xiaofei, GE Xingyan
Science & Technology Review. 2023, 41 (20): 64-70. ;  doi: 10.3981/j.issn.1000-7857.2023.20.007
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Abstract ( 60 )
Economic benefit is the first aim of land consolidation, and it is significant to analyze the influence of land consolidation on the profit of planting industry, which can improve the level of project design and agricultural management. In this article the typical project area of land consolidation was selected, the original data was collected by in situ field survey, and all the data were analyzed based on the theory of statistics. Now the preponderant crop in the study area is fruit, and the planting area proportion of grape is above 80%. The profit per unit area of grape is significantly higher than citrus and maize, and the difference are 114.3 k and 193.8 k yuan per ha, respectively. Generally, the new excellent variety reaches higher profit compared with ordinary variety. The average profit in the past three years remained stable, and in the enlargement course of the plot size, the profit per unit area rose at first, then declined dramatically and then rose again, and maintained in high level stably. It is found that the structure of planting industry has changed dramatically with the significant promotion of economic benefit, larger size plot should be designed and built as possible, and new excellent variety of predominant crop should be updated timely in the field management.
Reviews

Research progress on key technologies for drilling and completion of offshore gas hydrate

WANG Zhigang, GONG Jianyu, WU Jixiu, YIN Hao, SHI Shanshan, YAN Jia, LI Xiaoyang
Science & Technology Review. 2023, 41 (20): 71-78. ;  doi: 10.3981/j.issn.1000-7857.2023.20.008
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Abstract ( 86 )
Natural gas hydrate is a kind of solid crystalline substance formed by water and methane under high pressure and low temperature, which is considered as the clean energy with the most potential to replace fossil energy by all countries in the world. The status of gas hydrate pilot production in the United States, Japan, India, South Korea and China was summarized. It was pointed out that there were some technical problems for the drilling and completion of natural gas hydrate in the sea area, such as narrow drilling fluid density window, difficult bottom hole pressure control, difficult directional well deflection, poor wellbore and wellhead stability, difficult reservoir reconstruction, and difficult sand control. The research and development status of solid fluidization drilling technology, horizontal well drilling technology, dual gradient drilling technology, pressure controlled casing drilling technology, hydraulic jet micro hole drilling technology, drilling fluid technology, and completion sand control technology were reviewed, and it was proposed that the scientific research efforts such as sand production mechanism, sand production prediction, well completion, drilling and completion equipment and instrument development must be strengthened to provide technical support for large-scale exploitation of natural gas hydrate in sea area.

Fracturing technology development status and high efficiency fracturing technology on normal hydrostatic pressure shale gas

LIU Hu, ZUO Luo, YIN Decan, JIANG Tingxue, DUAN Hua, WANG Haitao
Science & Technology Review. 2023, 41 (20): 79-88. ;  doi: 10.3981/j.issn.1000-7857.2023.20.009
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Abstract ( 66 )
In view of the problems of poor development effect, unclear understanding of multi-cluster fracturing equilibrium expansion control and temporary plugging mechanism, and low-cost and high-efficiency fracturing technology system that has not yet been formed in the economic development of normal hydrostatic pressure shale gas,and based on reservoir characteristics and technology development status, low-cost and high-efficiency fracturing technology countermeasures for normal hydrostatic pressure gas are carried out. The results present that low cost, dense clusters, multi-stage temporary plugging, high-strength continuous pumping sand and increasing ESRV are the directions for continuous optimization of high-efficiency fracturing technology for normal hydrostatic pressure shale gas. Optimizing fracturing cost composition and applying new technologies are effective ways to reduce costs and enhancing production. The cluster spacing has a great influence on the fracturing effect, and the recommended range is 5-10 m. Plugging in the middle and early stage and increasing the plugging times can improve the temporary plugging effect. The higher the stress difference, the more times the temporary plugging is required to increase SRV. To improve the plugging effect, the beneficial time for plugging agent injection is in the middle of the construction for reservoirs with natural fractures density more than 0.5 fracture/m, while the beneficial time is in the early stage of construction for reservoirs with natural fractures density less than 0.5 fracture/m. Temporary plugging agent with particle size smaller than 40/70 mesh, fracturing fluid with viscosity greater than 12mPa·s, and pumping rate greater than 12m³/min with volume fraction less than 0.1 can enhance plugging fracturing effect. The quartz sand combination of 140/200 mesh (10%) + 70/140 mesh (30%) + 40/70 mesh (60%) and the ratio of sand and liquid greater than 7% are recommended to reduce the cost and to increase the production.

Advances in new diagnosis and current treatment of idiopathic central precocious puberty with Western medicine and Traditional Chinese medicine

DING Yicheng, WANG Hai, BAO Mulong, GU Shengnan
Science & Technology Review. 2023, 41 (20): 89-96. ;  doi: 10.3981/j.issn.1000-7857.2023.20.010
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Abstract ( 70 )
Children's health is a key concern in China at present. The incidence rate of precocious puberty in China is 2%, which is an important disease threatening children's physical and mental health. Idiopathic central precocious puberty (ICPP) is the most common type. This article reviews the current clinical research status, latest achievements, and cutting-edge trends of ICPP. The latest“Expert Consensus on Diagnosis and Treatment of Central Sexual Precocity (2022)”up-dates the age limit of central sexual precocity from 8 to 7.5 years old. Gene diagnosis is a new method to assist in the diagnosis of ICPP, and the“2022 Consensus”suggests that children with the family history of precocious puberty should undergo gene testing. GnRH agonists (GnRHa) are the gold standard treatment regimen for ICPP, which are beneficial for inhibiting bone age development, increasing the final adult height of children, reducing body mass index, and improving brain function. The traditional Chinese medicine treatment of ICPP is currently a research hotspot, including traditional Chinese medicine internal treatment, as well as external treatment methods such as ear acupoint pressing and massage, it has a significant therapeutic effect on ICPP, with its efficacy superior to GnRHa, and its safety may be better. Traditional Chinese medicine or a combination of traditional Chinese and Western medicine is expected to become a cutting-edge treatment option for ICPP.
Papers

Analysis on the security guarantee of new energy related minerals supply in China

LIU Binbin, GE Jianping
Science & Technology Review. 2023, 41 (20): 97-105. ;  doi: 10.3981/j.issn.1000-7857.2023.20.011
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Abstract ( 83 )
With the goal of carbon peaking and carbon neutralization in China, the demand for critical minerals in new energy transformation will grow rapidly. Four typical new energy related minerals of copper, lithium, cobalt and nickel are taken as the research objects in this study. This study analyzes the current situation and problems of new energy related minerals from four aspects: reserves security, supply and demand security, trade security and investment security. It is found that the supply security of new energy related minerals in China is faced with the problems of insufficient domestic reserves and contradiction between supply and demand. In addition, the centralized geographical distribution of imports and unstable production capacity of overseas mining investment projects also threaten the supply security of China’s new energy related minerals. In order to ensure the safe and stable supply of new energy minerals, the Chinese government and mining enterprises should improve the supply security capabilities domestically and overseas.
On the domestic front, the government and mining enterprises should strengthen the exploration and development of domestic resources and accelerate the layout of the whole mining industry chain. On the foreign side, the government and mining enterprises should expand overseas trade and investment cooperation and innovate the investment model of overseas mining projects.

A prediction model for coal calorific value based on L-M gradient iterative algorithm

HUANG Kui, WANG Chongshi, WANG Linli, DOU Youquan, ZHANG Donglian, ZENG Wenhui, WANG Jiayin, ZENG Yong
Science & Technology Review. 2023, 41 (20): 106-112. ;  doi: 10.3981/j.issn.1000-7857.2023.20.012
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Abstract ( 50 )
The coal quality test data of about 150 thermal power enterprises are selected, and the coal calorific value prediction model based on L-M algorithm is built by analyzing the ubiquitous coal quality test data information. The experimental results show that: (1) the linear relationships between calorific value and carbon, ash are significant respectively, and the correlation coefficients are 0.8768 and 0.6880; (2) principal component analysis(PCA) method excavates the information of the principal component eigenvalue, characteristic matrix and score, which could realize the dimension reduction effect from six-dimensional matrix to four-dimensional matrix, and enhance the convergence stability of neural network in the training process; (3) based on the L-M algorithm, the training coefficient , verification coefficient and test coefficient of the Levenberg-Marquardt back propagation neural network prediction method(LMBP) model are 0.9957, 0.9942 and 0.9963 respectively, and the overall coefficient is 0.9931. Through the further verification of 20 groups of data to be tested, the LMBP prediction model is more reliable, the prediction accuracy is higher, and better to meet the actual forecast demand.

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