Microstructure and mechanical properties of Co-28Cr-6Mo-0.22C investment castings by current solution treatment

This study examined the impact of current solution treatment on the microstructure and mechanical properties of the Co-28Cr-6Mo-0.22C alloy investment castings.The findings reveal that the current solution treatment significantly promotes the dissolution of carbides at a lower temperature.The optimal conditions for solution treatment are determined as a solution temperature of 1,125°C and a holding time of 5.0 min.Under these parameters,the size and volume fraction of precipitated phases in the investment castings are measured as6.2μm and 1.1vol.%.The yield strength,ultimate tensile strength,and total elongation of the Co-28Cr-6Mo-0.22C investment castings are 535 MPa,760 MPa,and 12.6%,respectively.These values exceed those obtained with the conventional solution treatment at 1,200°C for 4.0 h.The findings suggest a phase transformation of M_(23)C_(6)→σ+C following the current solution treatment at 1,125°C for 5.0 min.In comparison,the traditional solution treatment at 1,200°C for 4.0 h leads to the formation of M_(23)C_(6)and M_(6)C carbides.It is noteworthy that the non-thermal effect of the current during the solution treatment modifies the free energy of both the matrix and precipitation phase.This modification lowers the phase transition temperature of the M_(23)C_(6)→σ+C reaction,thereby facilitating the dissolution of carbides.As a result,the current solution treatment approach achieves carbide dissolution at a lower temperature and within a significantly shorter time when compared to the traditional solution treatment methods.

How R&D investment promotes green technology innovation in the context of digitalization?-An empirical analysis based on provincial panel data

Green technology innovation is an important driving force and source to promote my country’s high-quality development,and it is the core path to achieve sustainable development.This paper uses my country’s provincial panel data from 2016 to 2019 to study the impact mechanism of R&D investment on green technology innovation,and introduces the level of digitization,using the panel threshold model to discuss its role in the impact mechanism of R&D investment on green technology innovation.The study found that when the level of digitalization in a region is low,increasing R&D investment does not necessarily improve the ability of green technology innovation;when the level of digitalization is relatively high,R&D investment has a positive role in promoting green technology innovation.Therefore,it is necessary to improve policies to encourage enterprises to increase investment in research and development;at the same time,it is necessary to promote the coordinated development of digital foundation,digital investment,digital literacy,digital economy and digital application,and promote the deep integration of digitalization and green technology innovation.

National Social Investment Programmes in Nigeria:A Descriptive Analysis of the Socio-Economic Contributions of N-Power Programme in Benue State

This study analysed the socio-economic contributions of N-Power programme amongst the beneficiaries of the scheme in Benue State.Prior to the introduction of N-Power programme,successive administrations in Nigeria have made concerted efforts towards improving the standard of living of the citizenry through the execution of various welfare or social intervention programmes,but not much successes were recorded.Learning from the mistakes of the past regimes,and by way of deliberate state policy,the Buhari’s government initiated a multi-pronged social investment policy,one of which is the N-power programme that came onboard in 2016,which also doubles as the subject of this study.To achieve the goal of this study,a combination of desktop research and survey design was employed.Questionnaires were administered to 390 respondents through a combination of stratified and random sampling techniques.The results of the survey were matched with that of the secondary data obtained through online websites and other related sources.The result indicated that N-Power made positive contributions to the socio-economic life of the beneficiaries in Benue State:specifically,the scheme contributed in poverty eradication,employment generation,skills acquisitions and capacity building.However,some aspect of our findings revealed that the programme has a number of challenges such as:inadequate cash support,delay in monthly cash transfer to beneficiaries,distance participants had to move to their work stations,absence of posting in N-Teach scheme,and lack of adequate working tools amongst others.To salvage this problem the paper recommended the following solutions:expansion of the scheme to cover N-Teach and other aspects,increment in the monthly cash transfer to cushion the high rate of inflation,support for the participants/beneficiaries in transportation and logistics,enrolment of more youth into the various schemes,proper monitoring and evaluation of the implementation of the schemes amongst others.

基于PLUS-InVEST模型的陕南地区土地利用变化多情景模拟与碳储量评估

在PLUS模型中纳入POI驱动因子并利用LASSO回归进行驱动体系筛选与精度验证,设定自然发展、经济保护与生态保护3种情景,利用筛选后的驱动因子模拟2030年各情景下陕南地区的土地利用格局,利用InVEST模型分析2000—2020年陕南地区碳储量的时空分异特征,探讨不同发展情景下土地利用变化对陕南地区碳储量的影响。结果表明:(1)2000—2020年,陕南地区的建设用地面积由23648.49 hm^(2)增长到78000.21 hm^(2),侵占了耕地、林地和草地的生存空间,使其分别减少了39415.05 hm^(2),8787.51 hm^(2)与17476.56 hm^(2),2030年3种发展情景下的建设用地均保持扩张的趋势。(2)在PLUS模型中加入POI驱动因子且利用LASSO算法筛选驱动因子有效提升了模型的精度与运行效率,模型的Kappa系数和OA系数分别提高了2.53%和0.20%,更精准地模拟了建设用地的分布情况。(3)2000—2020年陕南地区碳储量总量呈下降趋势,由2.1887×10^(9)t下降至2.1775×10^(9)t。2030年经济保护情景与自然发展情景的碳储量总量均小于2020年,生态保护情景下的碳储量总量最高,达到了2.1830×10^(9)t。(4)生态保护情景更有利于陕南地区的可持续发展策略,以陕南地区平均碳密度分区分布为基础,可为陕南地区分区发展与区域碳收支平衡提供参考,对未来不同情景下土地利用对区域碳储量的影响和双碳背景下的国土空间规划具有借鉴意义。

基于InVEST-PLUS模型的陕西省水源涵养量估算及预测

[目的]为估算陕西省水源涵养量。[方法]通过耦合InVEST模型和PLUS模型,计算陕西省2000—2020年水源涵养量,并预测未来2030年土地利用变化下的水源涵养量。[结果]陕西省2000—2020年平均水源涵养量为132.25 mm,空间分布特征为水源涵养量由北向南逐渐增强。从植被类型来看,林地是陕西省水源涵养量的主体,年平均水源涵养量为199.55×10^(8)m^(3);从行政区来看,安康市水源涵养量最大(308.96 mm)。2030年陕西省水源涵养总量为285.16×10^(8)m^(3),相比2020年降低8.68×10^(8)m^(3)。[结论]陕西省未来2020—2030年水源涵养量呈略微下降趋势。

基于PLUS-InVEST模型的呼和浩特市多情景土地利用变化动态模拟及碳储量评估

为探究呼和浩特市土地利用变化对生态系统碳储量的影响,本研究基于InVEST模型与PLUS模型模拟预测呼和浩特市在自然发展、生态保护、耕地保护、城市发展4种情景下的土地利用与碳储量。结果表明:1990-2020年呼和浩特市不透水面、林地、草地、水体等土地利用类型的面积呈增加状态,耕地、裸地、灌木地等土地类型的面积呈减少状态,其中灌木地和裸地的土地转出率较高,分别为93.63%和98.24%。InVEST模型估算结果显示,不透水面不断扩张,侵蚀耕地等高碳密度土地类型,造成呼和浩特市1990-2020年碳储量呈逐年递减趋势。2030年自然发展、生态保护、耕地保护、城市发展情景模拟下的呼和浩特市的碳储量与2020年相比均呈现减少状态,其中耕地保护情景碳储量降幅最小,其次为生态保护情景,说明采取合理的保护措施能够有效抑制碳储量下降。耕地保护情景能够有效减缓城市建筑的扩张趋势,生态保护情景则可有效增加水体、草地等生态类用地面积。研究表明,落实耕地和生态保护政策、优化土地利用结构、提高土地利用效率对呼和浩特市的可持续发展均有重要意义。

基于CA-Markov和InVEST模型的昆明市土地利用与生境质量时空变化及预测

基于2000年、2010年和2020年3期GlobeLand30土地利用数据,采用CA-Markov和InVEST模型,通过预测2030年土地利用以及生境变化特征,揭示昆明市土地利用变化趋势及对其生境质量时空演变的影响,为生态环境可持续性发展提供参考。结果表明:①研究区以耕地、林地和草地为主,2000—2020年由于退耕还林还草政策的实施和社会经济快速发展,耕地面积比例持续降低,人造地表面积比例增加,其他类型变化不大。②预计2030年人造地表扩张速度加快,主要是来自耕地、林地和草地的转换,除人造地表和草地外,其他用地类型面积均为下降趋势。③研究区于2010年景观破碎化程度达到最高,2020—2030年破碎化程度持续降低,各类型景观趋于简单化和规则化。④研究区平均生境质量逐渐降低,低生境质量区域与高生境质量区域面积逐渐增加,两极分化态势逐渐明显。

基于PLUS-InVEST模型的生态脆弱区生境质量时空演变分析

基于PLUS模型预测阿坝州生态脆弱区2030年土地利用情况,并利用InVEST模型计算2000年、2010年、2020年及2030年生境质量,对其时空演变进行分析。结果表明,研究区草地、湿地退化情况显著且裸地持续增加,预计2030年裸地面积将达334.38 km^(2);与2000年相比将会有204.55 km^(2)湿地退化。驱动因子中,降雨是限制林地、湿地扩张的主要因素,侧面反映水源涵养功能的重要性;草地受各项因子的影响程度相差不大,一般生长在远离政府的地方,且其面积扩张受DEM限制;气温是导致裸地增加的主要因素。生境质量总体较高但空间分布差异较大,且有缓慢变差的趋势,预计2030年生境质量低的区域面积将比2000年增加670.28 km^(2),主要由扩张的耕地、建设用地造成。未来生境质量降低的速率将有所减缓,但仍需加强人工措施来阻止降低。

耦合PLUS-InVEST模型的南平市土地利用模拟与碳储量评估

为探究南平市不同发展导向下土地利用模拟对生态系统碳储量的影响,揭示碳储量时空变化特征和未来演变趋势,通过耦合InVEST模型和PLUS模型,分析了2005—2020年南平市土地利用及碳储量时空演化特征,并从自然发展、耕地保护和生态优先3种情景预测了2035年土地利用及碳储量变化.结果表明:2005—2020年南平市林地、草地和耕地面积总体上呈下降趋势,水域面积小幅度上升,建设用地面积则增长迅速,是由于建设用地的快速扩张侵占和挤压了大量的城市生态用地所致;南平市碳储量在15年间整体上呈现下降态势,累计损失了1.61×10^(6)t;在自然发展和耕地保护情景下,2035年南平市的碳储量较2020年预计将分别损失1.50×10^(6)t和3.62×10^(6)t;而在生态优先情景下,2035年的区域碳储量较2020年将上升38825.37 t;造成3种情景碳储量发生变化的主要因素是土地利用类型的改变,而林地和草地等生态用地向建设用地和耕地更多地转移,是导致碳储量下降的核心因素.开展科学有效的生态环境治理,可有效缓解碳储量下降问题,提升区域碳储量水平,加快落实双碳目标.

基于PLUS-InVEST模型的福建省土地利用变化与碳储量评估

[目的]福建省森林覆盖率高达66.8%,是我国森林覆盖率排名第1的省份。探讨福建省土地利用变化对碳储量时空变化的影响是探寻社会发展和生态保护平衡点的理论基础。[方法]基于PLUS模型和InVEST模型碳储量模块,揭示2000-2020年全省碳储量时空变化特征与土地利用类型之间的关系,并从自然发展、生态保护和城镇发展3种情景预测2020-2030年福建省碳储量时空变化。[结果]2000年、2010年和2020年研究区的总碳储量分别为214.77×10^(7),214.51×10^(7),212.93×10^(7) t,呈逐年下降趋势。人类活动对土地的开发和改造是导致碳储量变化的主导因素,大面积的耕地和林地转变为建设用地是导致碳储量降低的直接原因。预测结果认为,与2020年相比,2030年自然发展、生态保护和城镇发展情景下碳储量分别减少1.47×10^(7) t,增加0.17×10^(7) t,减少1.85×10^(7) t。生态保护情景是唯一逆转碳储量下降的发展情景,该情景与2020年相比,林地面积扩张1900.87 km 2,林地碳储量增长2.08×10^(7) t,在切实保护生态的同时也能够满足城镇发展的土地需求。[结论]落实以林地保护为主,控制建设用地是福建省实现“双碳”目标的重要前提。

基于PLUS-InVEST模型的珠三角碳储量时空演变与预测

[目的]探究珠三角地区2005—2020年土地利用变化及其对碳储量的影响,并对2035年珠三角的土地利用格局和碳储量进行模拟预测,以期为珠三角地区“双碳”目标下的国土空间规划和生态决策提供科学依据。[方法]基于2005—2020年4期土地利用数据,以珠三角城市群为研究区域,采用PLUS模型和InVEST模型对该区的土地利用变化和碳储量演变进行分析,并预测其2035年土地利用空间格局和碳储量变化趋势。[结果]①2005—2020年,珠三角地区碳储量先增加后减少,林地、建设用地和未利用地增多促进碳储量增长了4.82×10^(7)t,耕地、草地和水域减少导致碳储量减少了5.10×10^(7)t。②预计2035年,随着建设用地和林地的增加,该区碳储量较2020年增长5.75×10^(7)t,生态环境向好发展。③该区碳储量表现出“四周高,中部低”的空间分布格局,与土地利用空间分布具有显著一致性,即碳储量高值区集中在林地、耕地和草地,碳储量低值区集聚在建设用地。[结论]随着未来城市发展需要,政府部门应进行土地综合开发利用,采取生物、工程技术等生态修复措施,提升区域固碳能力,助力实现碳中和目标。

基于PLUS-InVEST模型的天山北坡生态系统碳储量时空变化与预测

土地利用变化作为影响陆地生态系统碳储量的重要因素,研究两者间的关系对维持区域碳平衡和实现双碳目标具有重要意义。基于第三次新疆综合科学考察背景,分析天山北坡1990年、2000年、2010年、2020年土地利用变化与碳储量的定量关系,结合PLUS和InVEST模型,模拟在历史趋势、水资源保护和经济发展3种情景下2030年区域碳储量的空间格局。结果表明:(1)草地和裸地是天山北坡主要土地覆被类型,1990—2020年耕地、林地、水域、建设用地和湿地面积增加,耕地面积增加最多,其余土地利用类型面积减少,草地减少最多。(2)1990—2020年天山北坡碳储量呈“先升后降”趋势,草地、裸地、耕地和林地间的转化是总碳储量变化的主要成因。(3)3种情景下碳储量均低于2020年水平,经济发展情景减幅最为显著,草地减少、裸地增加是碳损失的主要原因。

基于PLUS-InVEST的济南多情景土地利用变化模拟与碳储量评估

土地利用类型变化和人类社会活动带来的碳排放问题日益严重。以济南市为研究区域,对济南市2000—2020年的土地利用变化和碳储量变化进行了研究,并基于PLUS-InVEST模型对不同发展情景下济南市2040年的土地利用和碳储量进行了预测,结果表明:土地利用变化对济南市碳储量具有重要影响,与2000年相比,2020年济南市的碳储量减少;2040年生态保护情景下碳储量下降最少,城镇发展情景下碳储量下降最多;不同土地利用类型之间的转换会对碳储量产生影响,林地碳密度高,林地转换为其他用地会导致碳储量减少。

基于InVEST-PLUS模型的黄河流域内蒙古段生态系统碳储量评价及预测

陆地生态系统碳储量对减缓全球气候变暖有重要意义,评估黄河流域内蒙古段土地利用变化对碳储量变化的影响,可以为“双碳”目标的实现提供助力。本研究运用InVEST模型对黄河流域内蒙古段过去20 a的碳储量进行评估,运用PLUS模型预测了2040年3种不同发展情景下的土地利用格局,并耦合InVEST-PLUS对黄河流域内蒙古段未来20 a的碳储量进行估算,探讨土地利用变化和碳储量之间的响应关系。结果表明:2000—2020年黄河流域内蒙古段草地是主要土地利用类型和最重要的碳库。草地面积增加是黄河流域内蒙古段碳储量上升的主要原因,碳储量累计上升4.08×10^(7)t。在生态保护情景下,最有利于2040年黄河流域内蒙古段碳储量的增加,可使碳储量累计增加4.50×10^(7)t。年均降水是解释度最高的单因子影响因素,随着社会经济的发展,社会经济因子对碳储量时空分异特征的解释度增加。双因子交互影响的解释度普遍远高于单因子对于碳储量时空分异特征的解释度。本研究以期为区域用地规划提供建议,为我国更好的实现碳中和目标提供服务。

基于InVEST模型的碳储量时空变化研究--以长株潭城市群为例

碳中和、碳达峰作为应对气候变化的关键战略,在实现区域可持续发展中发挥着重要作用。碳储量是衡量生态系统中碳存储量的关键指标。因此,本研究以长株潭城市群为研究对象,基于2000年和2020年的土地利用数据,通过InVEST模型对其碳储量进行了全面量化,并结合土地利用变化转移分析,探究了长株潭城市群碳储量时空变化的特征。结果表明:2000—2020年,长株潭城市群总碳储量呈现下降趋势,共减少了10.23×10^(6) t,平均碳储量减少了0.30t·hm^(-2);在空间分布上,长株潭城市群的碳储量呈现东南高西北低的空间格局,过去20年间碳储量低值区域面积显著增加;在长株潭城市群区域,土地利用类型在过去的20年间发生了明显转变,其中建设用地、灌丛、水体和草地的占地面积有所增加,而耕地和林地的面积大幅度减少;在快速城市化进程中耕地和林地大量转向建设用地是碳储量下降的主导因素。因此,在未来的城市规划中,应该严格坚守城市建设边界,限制城市化对林地等高碳密度土地的进一步侵蚀,减缓碳储量的损失。此外,在城市化进程中需要注重可持续土地利用规划,以保障生态系统服务的稳定供给。研究结果可为长株潭城市群的生态管理和空间规划提供科学依据和决策支持,对于实现碳中和目标和城市可持续发展具有重要意义。

Risk assessment of oil and gas investment environment in countries along the Belt and Road Initiative

With the implementation of the Belt and Road Initiative, China is deepening its cooperation in oil and gas resources with countries along the Initiative. In order to better mitigate risks and enhance the safety of investments, it is of significant importance to research the oil and gas investment environment in these countries for China's overseas investment macro-layout. This paper proposes an indicator system including 27 indicators from 6 dimensions. On this basis, game theory models combined with global entropy method and analytic hierarchy process are applied to determine the combined weights, and the TOPSIS-GRA model is utilized to assess the risks of oil and gas investment in 76 countries along the Initiative from 2014 to 2021. Finally, the GM(1,1) model is employed to predict risk values for 2022-2025. In conclusion, oil and gas resources and political factors have the greatest impact on investment environment risk, and 12 countries with greater investment potential are selected through cluster analysis in conjunction with the predicted results. The research findings may provide scientific decisionmaking recommendations for the Chinese government and oil enterprises to strengthen oil and gas investment cooperation with countries along the Belt and Road Initiative.

Temporal and spatial variation and prediction of water yield and water conservation in the Bosten Lake Basin based on the PLUS-InVEST model

To comprehensively evaluate the alterations in water ecosystem service functions within arid watersheds,this study focused on the Bosten Lake Basin,which is situated in the arid region of Northwest China.The research was based on land use/land cover(LULC),natural,socioeconomic,and accessibility data,utilizing the Patch-level Land Use Simulation(PLUS)and Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)models to dynamically assess LULC change and associated variations in water yield and water conservation.The analyses included the evaluation of contribution indices of various land use types and the investigation of driving factors that influence water yield and water conservation.The results showed that the change of LULC in the Bosten Lake Basin from 2000 to 2020 showed a trend of increasing in cultivated land and construction land,and decreasing in grassland,forest,and unused land.The unused land of all the three predicted scenarios of 2030(S1,a natural development scenario;S2,an ecological protection scenario;and S3,a cultivated land protection scenario)showed a decreasing trend.The scenarios S1 and S3 showed a trend of decreasing in grassland and increasing in cultivated land;while the scenario S2 showed a trend of decreasing in cultivated land and increasing in grassland.The water yield of the Bosten Lake Basin exhibited an initial decline followed by a slight increase from 2000 to 2020.The areas with higher water yield values were primarily located in the northern section of the basin,which is characterized by higher altitude.Water conservation demonstrated a pattern of initial decrease followed by stabilization,with the northeastern region demonstrating higher water conservation values.In the projected LULC scenarios of 2030,the estimated water yield under scenarios S1 and S3 was marginally greater than that under scenario S2;while the level of water conservation across all three scenarios remained rather consistent.The results showed that Hejing County is an important water conservation function zone,and the eastern part of the Xiaoyouledusi Basin is particularly important and should be protected.The findings of this study offer a scientific foundation for advancing sustainable development in arid watersheds and facilitating efficient water resource management.

Agricultural Investment Project Decisions Based on an Interactive Preference Disaggregation Model Considering Inconsistency

Agricultural investment project selection is a complex multi-criteria decision-making problem,as agricultural projects are easily influenced by various risk factors,and the evaluation information provided by decisionmakers usually involves uncertainty and inconsistency.Existing literature primarily employed direct preference elicitation methods to address such issues,necessitating a great cognitive effort on the part of decision-makers during evaluation,specifically,determining the weights of criteria.In this study,we propose an indirect preference elicitation method,known as a preference disaggregation method,to learn decision-maker preference models fromdecision examples.To enhance evaluation ease,decision-makers merely need to compare pairs of alternatives with which they are familiar,also known as reference alternatives.Probabilistic linguistic preference relations are employed to account for the presence of incomplete and uncertain information in such pairwise comparisons.To address the inconsistency among a group of decision-makers,we develop a pair of 0-1mixed integer programming models that consider both the semantics of linguistic terms and the belief degrees of decision-makers.Finally,we conduct a case study and comparative analysis.Results reveal the effectiveness of the proposed model in solving agricultural investment project selection problems with uncertain and inconsistent decision information.

Chinese Enterprises’ Investment in Southeast Asia Continues Unabated

As we all know,Southeast Asia has become a hot destination for Chinese enterprises to invest in.The latest report shows that Southeast Asia continues to attract China’s capital,within which the medical industry has become an important area for Chinese enterprises to invest in,and the investment activity has gradually warmed up despite fluctuations.

How to Further Attract and Stabilize Foreign Investment

During the Two Sessions,how to attract foreign investment to China and how to further optimize the business environment for foreign investment have become hot topics in the economic field.The 2024 government work report proposes increased efforts to attract foreign investment.It will continue to reduce the negative list of foreign investment access,completely lift restrictions on foreign investment accessto the manufacturing industry.