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Can whole steps of grain production be outsourced? Empirical analysis based on the three provinces of Jiangsu,Jilin,and Sichuan in China

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Journal of Integrative Agriculture 2024年第1期23卷 336-347页

作者： Jiacheng Liu Shengzhi Mao Qiufen Zheng Zhigang Xu School of Finance and Taxation Nanjing University of Finance and EconomicsJiangsu 210023China School of economics Southwestern University of Finance and EconomicsSichuan 611130China School of economics and Management Nanjing Agricultural UniversityJiangsu 210095China

Certain outsourcing services for agricultural management in China,such as pest control in grain production,have experienced prolonged sluggishness,contrasting with the relatively high level of outsourcing services observed in harvesting,land preparation,and sowing.This study examines the feasibility of implementing whole-step outsourcing in grain production by conducting a case study of rice and maize production in Jiangsu,Jilin,and Sichuan provinces in China.The provision of outsourcing services hinges on two essential conditions:technological advancements fostering specialized production and economies of scale,coupled with a market size sufficient to realize the aforementioned potential economies of scale.The results showed that outsourcing pest control or harvesting services had varying economies of scale.The outsourcing services in pest control were less common than in harvesting services,and their marginal growth space of the economies of scale with technological change was also smaller.Determined by the operational characteristics of pest control itself,the market scale of its professional services is small.Therefore,achieving the whole-step outsourcing of grain production necessitates not only technological innovation but also effective policy interventions to overcome the constraints of market scale.Such interventions include(1)optimizing crop layouts between planning regions and reducing land fragmentation and(2)supplying timely and effective inter-regional agricultural information for service providers aided by information technology.

关键词： outsourcing services economy of scale technical conditions market scale

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Wettability,reactivity,and interface structure in Mg/Ni system

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Journal of Magnesium and Alloys 2024年第2期12卷 659-672页

作者： S.Terlicka N.Sobczak Ł.Maj P.Darłak J.J.Sobczak Institute of Metallurgy and Materials Science Polish Academy of Sciences25 Reymonta Str.KrakowPoland Faculty of Foundry Engineering AGH University23 Reymonta Str.KrakowPoland

The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni substrates.For comparison,the experiments were performed in two variants:(1)using the Capillary Purification(CP)procedure,which allows the non-contact heating and squeezing of a pure oxide-free Mg drop;(2)by classical Contact Heating(CH)procedure.The high-temperature tests were performed under isothermal conditions(CP:760℃for 30 s;CH:715℃for 300 s)using Ar+5 wt%H_(2) atmosphere.During the sessile drop tests,images of the Mg/Ni couples were recorded by CCD cameras(57 fps),which were then applied to calculate the contact angles of metal/substrate couples.Scanning and transmission electron microscopy analyses,both coupled with energy-dispersive X-ray spectroscopy,were used for detailed structural characterization of the solidified couples.It was found that an oxide-free Mg drop obtained by the CP procedure showed a wetting phenomenon on the Ni substrate(an average contact angleθ<90°in<1 s),followed by fast spreading and good wetting over the Ni substrate(θ_((CP))~20°in 5 s)to form a final contact angle ofθ_(f(CP))~18°.In contrast,a different wetting behavior was observed for the CH procedure,where the unavoidable primary oxide film on the Mg surface blocked the spreading of liquid Mg showing apparently non-wetting behavior after 300 s contact at the test temperature.However,in both cases,the deep craters formed in the Ni substrates under the Mg drops and significant change in the structure of initially pure Mg drops to Mg-Ni alloys suggest a strong dissolution of Ni in liquid Mg and apparent values of the final contact angles measured for the Mg/Ni system.

关键词： Magnesium-based alloys Sessile drop tests Capillary purification procedure Wettability Reactivity Contact angle

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Women’s empowerment and food consumption:Evidence from female-headed households in Tanzania

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Journal of Integrative Agriculture 2024年第2期23卷 457-467页

作者： Mosses Lufuke Xu Tian College of economics and Management Nanjing Agricultural UniversityNanjing 210095China Department of economics The University of DodomaDodoma 41218Tanzania College of economics and Management China Agricultural UniversityBeijing 100083China Academy of Global Food economics and Policy China Agricultural UniversityBeijing 100083China

Despite the growing recognition of women’s increasing role in the household and corresponding empowerment programs in sub-Saharan Africa,intensive research on the relationship between women’s influence and household food consumption is minimal.Using the most recent(2017-2018)national household survey data from Tanzania,this study examined the influence of women’s empowerment on household food consumption.First,we compared the monthly consumption of eight food categories between female-headed households(FHHs)and male-headed households(MHHs)using both descriptive statistics and the propensity score matching(PSM)method.Furthermore,we adopted the two-stage Linear Expenditure System and Almost Ideal Demand System model(LES-AIDS)to estimate income and price elasticities for the two household types.The results show that FHHs consume bread and cereals,fish,oils and fats,vegetables,and confectionery(sugar,jam,honey,chocolate,etc.)more than MHHs.Moreover,FHHs have a significantly higher income elasticity of demand for all food groups than MHHs.They are also more price elastic than MHHs in meat,fish,oils,fats,sugar,jam,honey,chocolate,etc.

关键词： women’s empowerment food consumption income elasticity price elasticity

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Non-Convex Optimization of Resource Allocation in Fog Computing Using Successive Approximation

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Journal of Systems Science & Complexity 2024年第2期37卷 805-840页

作者： LI Shiyong LIU Huan LI Wenzhe SUN Wei School of economics and Management Yanshan UniversityQinhuangdao 066000China

Fog computing can deliver low delay and advanced IT services to end users with substantially reduced energy consumption.Nevertheless,with soaring demands for resource service and the limited capability of fog nodes,how to allocate and manage fog computing resources properly and stably has become the bottleneck.Therefore,the paper investigates the utility optimization-based resource allocation problem between fog nodes and end users in fog computing.The authors first introduce four types of utility functions due to the diverse tasks executed by end users and build the resource allocation model aiming at utility maximization.Then,for only the elastic tasks,the convex optimization method is applied to obtain the optimal results;for the elastic and inelastic tasks,with the assistance of Jensen’s inequality,the primal non-convex model is approximated to a sequence of equivalent convex optimization problems using successive approximation method.Moreover,a two-layer algorithm is proposed that globally converges to an optimal solution of the original problem.Finally,numerical simulation results demonstrate its superior performance and effectiveness.Comparing with other works,the authors emphasize the analysis for non-convex optimization problems and the diversity of tasks in fog computing resource allocation.

关键词： Fog computing non-convex optimization optimal resource allocation successive approximation method utility function

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Customer Joining Behavior and Regulation Strategy in Visible Multi-Server Queues with Synchronous Vacations of Partial Servers

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Journal of Systems Science & Complexity 2024年第3期37卷 1209-1232页

作者： SUN Wei WANG Hao XIE Xumeng LI Shiyong School of economics and Management Yanshan UniversityQinhuangdao 066004China

This paper studies customer joining behavior and system regulation strategy in nonexhaustive visible M/M/m queues with synchronous vacations of a part of the servers.Once this part of the servers are idle,they take multiple vacations simultaneously(vacation period).Until there are customers waiting in the queue,they are reactivated and all servers are busy or idle(busy period).The authors call this part of the servers as“partial servers”.In view of the fully visible queue and the almost visible queue,the authors obtain customers’equilibrium joining threshold strategies and their socially optimal joining threshold strategies,respectively,and observe that customer joining behavior in equilibrium generally makes the system overcrowded,which makes the equilibrium social welfare lower than the optimal social welfare.After regulation,interestingly,for optimizing social welfare,the system manager hopes not only customers arriving in vacation period pay attention to the number of partial servers,but also customers arriving in busy period should care about it rather than ignore.Moreover,arranging more servers for vacation does not necessarily lead to the decrease of social welfare on condition that the number of partial servers is close to m.As for the information advantage of the fully visible case,it is not obvious for increasing social welfare and even unfavorable to servers’profit unless the number of partial servers is big enough.Furthermore,given the different composition of social welfare,there exists the optimal number of partial servers and the optimal arrival rate of customers for maximizing social welfare.

关键词： Customer behavior non-exhaustive service partial servers regulation strategy synchronous vacations visible queue

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Global Spillovers of China's Monetary Policy

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China & World Economy 2024年第3期32卷 1-30页

作者： Wenni Lei Dongzhou Mei Mi Zhang School of economics Minzu University of ChinaChina School of International Trade and economics Central University of Finance and EconomicsChina

Spillovers from China's monetary policy have become increasingly obvious with China's growing importance in the global economy and its close economic and trade ties with the world.This study establishes a proxy structure vector autoregression model to investigate the magnitude and transmission channel of spillovers from China to global and regional economies,taking advantage of high-frequency changes in asset prices in the financial markets to identify monetary policy shocks.The analysis reveals that China's monetary policy can affect the global economy by influencing international trade and commodity prices but there is no evidence of China's monetary policy affecting global financial variables.Tightness in China's monetary policy can cause a decline in world output whereas expansion in monetary policy can support global trade and output.This study also finds that the response of emerging Asian economies to China's monetary policy shock was nearly twice that of developed economies,while the transmission path did not change.The results of this study are consistent with the stylized fact that China's monetary policy plays an important role in the global trade and commodity cycle,although it does not drive the global financial cycle.

关键词： China's monetary policy commodity prices external instruments global trade spillovers

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Foreign Ownership and International Trade Performance in China

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China & World Economy 2024年第2期32卷 42-72页

作者： Zhiyuan Li Yichun Lin Mingyao Xu School of economics Fudan University Shanghai Institute of International Finance and economics China School of economics Fudan UniversityChina

We investigate the causal relationship between foreign ownership and international trade performance by comparing foreign-acquired firms with similar domestic-acquired firms in China with regard to changes in their post-acquisition international trade performance.Our findings indicate that foreign ownership significantly enhanced the probability of both exporting and importing,and strongly increased trade value.Foreign ownership took effect from the year of the acquisition and persisted for at least 2 years.It stimulated both processing trade and ordinary trade,and expanded products and trading partners.Post-acquisition trade performance also exhibited heterogeneity based on the different pre-acquisition and post-acquisition ownership.As for the underlying mechanisms,we show that firms experienced significant output expansion,increased export dependence,and eased financial constraints after foreign acquisition.

关键词： domestic acquisition foreign acquisition foreign ownership international trade performance

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Climbing the Export Quality Ladder:Role of Human Capital

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China & World Economy 2024年第2期32卷 125-159页

作者： Xiaogang He Ruifeng Teng Dawei Feng School of Applied economics Jiangxi University of Finance and EconomicsChina

This study assesses the effect of human capital expansion on China's export product quality.It employs the difference-in-differences(DID)framework based on a quasi-natural experiment investigating the 1999 higher education enrollment expansion as the exogenous policy shock.The empirical results confirm that human capital expansion appreciably improved the quality of China's export products.Human capital expansion promoted the transformation and upgrading of old products and the development of new products in term of intensive margin;it strengthened the endowment advantages of incumbent high-quality export enterprises while preventing low-quality enterprises from entering the market through price competition on the extensive margin.This prevented quality decline.Further,the study reveals that the improvement effect driven by human capital came from both innovation-induced and managerial efficiency improvement channels and was more prominent for large or foreign-funded enterprises in the eastern region.Our findings highlight the role of human capital in China's remarkable export performance from an endogenous growth perspective.

关键词： endogenous growth export product higher education expansion human capital quality improvement

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Will the State-owned Capital Transfer Policy Enhance the Sustainability of the Urban Employee Basic Pension Insurance Fund in China?

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China & World Economy 2024年第3期32卷 98-129页

作者： Jia Wang Huan Liu Mei Li Han Li School of economics Xiamen UniversityChina School of economics and Management Nanjing Agricultural UniversityChina School of economics and Management Wuhan UniversityChina

To analyze the efect of the state-owned capital transfer policy on the sustainability of China's urban employee basic pension insurance fund(CUEBPIF),this study develops an actuarial model for pension insurance.The results reveal the following:(i)Without policy intervention,the CUEBPIF would face a deficit in 2027 and a cumulative shortfall of RMB207.44 trillion by 2050,and the proportion of fiscal subsidies for the CUEBPIF in the total fiscal expenditure would increase to 12.86 percent in 2050.(i)Based on a delayed retirement policy,the transfer of 10 percent of state-owned capital can delay the onset of the fund deficit by 6 years,and the accumulated shortfall in 2050 would fall to RMB39.42 trillion,and the proportion of fiscal subsidies would decrease by I1.77 percentage points.(ii)The state-owned capital transfer policy can improve the sustainability of the CUEBPIF and reduce the burden of enterprise social security contributions when the transfer ratio increases to 20 percent.

关键词： burden of enterprise social security contributions delayed retirement policy state-owned capital transfer policy sustainability of basic pension insurance fund

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Tracking the change in Spanish greenhouse gas emissions through an LMDI decomposition model:A global and sectoral approach

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Journal of Environmental Sciences 2024年第5期139卷 114-122页

作者： Paula Fernández González María José Presno Manuel Landajo Department of Applied economics University of OviedoAuda del Cristos/n 33011 OviedoSpain

The reduction of GHG emissions to reverse the greenhouse effect is one of the main challenges in this century.In this paper we pursue two objectives.First,we analyze the evolution of GHG emissions in Spain in 2008–2018,at both the global and sectoral levels,with the variation in emissions decomposed into a set of determining factors.Second,we propose several actions specifically oriented to more tightly controlling the level of emissions.Our results showed a remarkable reduction(18.44%)in GHG emissions,mainly due to the intensity effect,but also to the production-per-capita effect.We detected somewhat different patterns among the various sectors analyzed.While the intensity effect was the most influential one in the agricultural,transport,and others sectors,the production-per-capita effect was predominant in the case of industry.The carbonization effect was revealed as crucial in the commerce sector.The above findings highlight the importance of the energy efficiency measures taken in recent years in the Spanish economy,also pointing to the need to deepen those strategies and to propose new measures that entail greater efficiency in emissions.Additional efforts in areas like innovation,R&D,diffusion of more eco-friendly technologies,and a greater use of greener energies all prove to be essential reduction actions to fight the greenhouse effect.

关键词： LMDI Decomposition Spain GHG emissions

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