The multiple roles of crop structural change in productivity,nutrition and environment in China:A decomposition analysis

China's crop structure has undergone significant changes in the last two decades since 2000,with an increase in the share of cereals,vegetables,and fruit,squeezing out other crops.As a result,land productivity,nutrient supply,and carbon emissions have changed.How to reallocate limited farmland among crops to achieve the multiple goals of agrifood systems becomes an important issue.This study explores the sources of land productivity and nutrition supply growth and carbon emissions reduction,and identifies the multiple roles of crop structural change from 2003 to 2020 based on a decomposition analysis.The results reveal that the growth within crops is still the primary driver in land productivity and nutrition supply and the reduction in carbon emissions.However,structural change also plays various roles at different periods.From 2003 to 2010,crop structural change increased the total calorie supply but lowered land productivity and contributed at least 70%of the total growth of carbon emissions.The crop structure was relatively stable,and their effects were modest from 2010 to 2015.From 2015 to 2020,the crop structural change began to play a greater role and generate synergistic effects in improving land productivity,micronutrient supply,and reducing carbon emissions,contributing to approximately a quarter of the growth of land productivity and 30%of total carbon emissions reduction.These results suggest that strategies for crop structural change should comprehensively consider its multiple impacts,aiming to achieve co-benefits while minimizing trade-offs.

Multifractal analysis of white matter structural changes on 3D magnetic resonance imaging between normal aging and early Alzheimer's disease

Applications of multifractal analysis to white matter structure changes on magnetic resonance imaging（MRI） have recently received increasing attentions. Although some progresses have been made, there is no evident study on applying multifractal analysis to evaluate the white matter structural changes on MRI for Alzheimer＇s disease（AD） research. In this paper, to explore multifractal analysis of white matter structural changes on 3D MRI volumes between normal aging and early AD, we not only extend the traditional box-counting multifractal analysis（BCMA） into the 3D case, but also propose a modified integer ratio based BCMA（IRBCMA） algorithm to compensate for the rigid division rule in BCMA. We verify multifractal characteristics in 3D white matter MRI volumes. In addition to the previously well studied multifractal feature,△α, we also demonstrated △ f as an alternative and effective multifractal feature to distinguish NC from AD subjects.Both △α and △ f are found to have strong positive correlation with the clinical MMSE scores with statistical significance.Moreover, the proposed IRBCMA can be an alternative and more accurate algorithm for 3D volume analysis. Our findings highlight the potential usefulness of multifractal analysis, which may contribute to clarify some aspects of the etiology of AD through detection of structural changes in white matter.

Structural Changes of Activated Carbon Electrodes for EDLCs in the Manufacturing Process

Supercapacitors,or electric double-layer capacitors(EDLCs),are the new generation of energy storage devices to store electrical charges and provide high power densities and long cyclic life compared to other storage devices.EDLC mainly consists of activated carbon electrodes and an electrolyte,and the performance of EDLC depends on the activated carbon electrodes.In this work,the structural changes of activated carbon electrodes are analyzed using commercial 2.7 V/9500F EDLCs in its manufacturing process.It is found that there is no significant change in morphology and crystal structure of the activated carbon,but its specific surface area(SSA)reduced greatly.The SSA of activated carbon was decreased by 23%after they were manufactured or converted into electrodes and finally retained only 40%of SSA after the capacitance test.Besides,the SSA of the positive electrodes was found to decrease critically than that of the negative electrodes.The SSA of the external positive electrodes is only 14.3%after fl oating test at 65℃.

Studies on Structural Changes of Collagen in Silicosis

In order to provide scientific information on the prevention and treatment of silicosis,studies about changes of silicotic collagen in lungs were carried out. In this paper, we present experiments about the structural changes of collagen in silicotic lungs of rats and patients. These included electron microscopy, circular dichroism and infrared spectroscopy studies of collagen fibers. The results indicated that fibers of silicotic collagen were shorter in length, smaller in diameter and decreased in α-helix content. The -Si-O-R- group and -OH group were found increased and -C-C- backbone shortened. The increase of -Si-O-R-group indicated that silica formed linking bridges between collagens which may be the cause of progressive enlargement of nodules

Study of Local Structural Changes on Air Cooling at the End of Rotor Windings for Variable Speed Pumped Storage Generator-Motor

The shrink fit retaining ring is currently the easiest to install and the most widely used end fixed for structure AC excitation variable speed generator-motor rotor end windings.However,the current research on the effect of high strength sealing on the ventilation and heat dissipation performance of the end is not enough.In this paper,based on the actual structural parameters and periodic symmetry simplification,the three-dimensional coupled calculation model of fluid field and temperature field is established.After solving the fluid and thermal equations,the influence of the length of rotor support block,the height of rotor support block,and the number of rotor support block on the fluid flow and temperature distribution in the rotor end region of generator-motor is studied using the finite volume method.The rheological characteristics of the air in the rotor domain,such as velocity and inter-winding flow,are analyzed.The law of temperature variation with local structure in the computational domain is studied.The variation law of cooling medium performance inside the large variable speed power generator motor is revealed.

High Resolution Electron Microscopy Observations of Structural Changes in Iron Nitride Films Annealed in Vacuum

Iron-nitride films were prepared by reactive sputtering, and the effect of annealing treatment on the structures was investigated by means of in-situ electron microscopy and high resolution electron microscopy (HREM). As-deposited films were observed to be a mixed structure of a few ultrafine epsilon-Fe2-3N particles existing in the amorphous matrix. it was found that the structure-relaxation in the amorphous occurred at 473 K, and the ultrafine grains began to grow at the higher annealing temperatures. The transition of the amorphous to epsilon-Fe2-3N was almost completed at 673 K. It is considered that the formation of the ideal epsilon-Fe3N is originated from the ordering of the nitrogen atoms during the annealing in vacuum. On the other hand, gamma'-phase (Fe4N) was seen to precipitation of epsilon-phase at 723 K. Two possible modes are proposed in the precipitation of gamma'-phase, depending on the heating rate and crystallographic orientation relationships, i.e. [121](epsilon)//[001](gamma), (2(1) over bar0$)(epsilon)//(110)(gamma) and [100](epsilon)//[110](gamma), (001)(epsilon)//(111)(gamma). In addition, alpha-Fe particles were observed to form from the gamma'-phase at high temperatures. We assumed that these structural changes are due to the diffusion of nitrogen and iron atoms during the annealing, except for the case of the precipitation of the gamma'-phase as depicted above. The results obtained in this work are in a good agreement with the assumption.

Artificial Intelligence,Structural Change and Labor Income Share

Artificial intelligence(AI)is a strategic technology that leads a new round of technological revolution and structural transformation.This paper studies the effects of AI on structural change and factor income shares.As a general purpose technology and new infrastructure,AI may substitute either labor or capital and its application has differential prospects across sectors.With a multi-sector general dynamic equilibrium model,we find that AI services or AI-specific technologies will reallocate factors between sectors.The direction of the reallocation depends on sectoral differences in the output elasticity of AI and in the elasticity of substitution between AI and traditional modes of production.The process of structural change will in turn change the labor income share.This paper presents the theoretical conditions for the direction of these changes and the underlying economic mechanism.We derive policy implications about how to promote high-quality development with AI.

Effects of Infrastructure Investment on Structural Change and Productivity Growth in China

The rapid growth of infrastructure investment is a salient feature of China’s economy since the reform and opening-up in 1978,contributing to not only the aggregate demand but also the structural change and productivity growth on the supply-side.This paper builds a multi-sector general equilibrium model to show how infrastructure investment influences structural change through price,investment and income effects,and influences productivity growth through the intensive and extensive marginal effects.By quantifying the model with China’s economy for the period 1981-2017,the paper finds that the infrastructure investment restrained the rise of services,but boosted productivity growth over the period.The policy implication is that China should ramp up infrastructure investment to increase productivity as it pursues high-quality development,but give priority to new infrastructure and public-interest infrastructure to promote industrial structural upgrade.

A Fluctuation Test for Structural Change Detection in Heterogeneous Panel Data Models

Structural change in panel data is a widespread phenomena. This paper proposes a fluctuation test to detect a structural change at an unknown date in heterogeneous panel data models with or without common correlated effects. The asymptotic properties of the fluctuation statistics in two cases are developed under the null and local alternative hypothesis. Furthermore, the consistency of the change point estimator is proven. Monte Carlo simulation shows that the fluctuation test can control the probability of type I error in most cases, and the empirical power is high in case of small and moderate sample sizes. An application of the procedure to a real data is presented.

The Future is in the Past： Projecting and Plotting the Potential Rate of Growth and Trajectory of the Structural Change of the Chinese Economy for the Next 20 Years

Based on the convergence hypothesis and referring to the experience of East Asian high-performing economies from 1950 to 2010, this paper projects and plots the potential growth rate of the Chinese economy over the next 20years. It predicts that the potential growth rate of per capita GDP adjusted by purchasing power parity averages at 6. 02 percent from 2015 to 2035, while the potential GDP growth rate of 2015 would still be above 8percent, which implies that the realized rate of growth has not reached its potential since 2012. Besides, based on the per capita GDP projected and on cross -country comparison, the paper plots the trajectory of structural change of the Chinese economy from 2015 to 2035. The result shows that： （i） the value-added share of primary industry will drop more rapidly than the employment share; （ii） the value-added share of secondary industry will decline and employment share will present an inverted U shape whose turning point will probably come between 2020 and 2025; （iii） both the value-added and employment share of tertiary industry will increase continuously.

Labor Market Dynamics and Structural Change： Evidence from China

Structural change theories usually assume agents are homogeneous. However, because of demand-side or supply-side heterogeneities, the probability of switching among sectors differs across people. This paper reveals these differences through restoring a long-period, individual-level panel dataset from China＇s Urban Household Survey for 1986-2009. We find that both for people who started working for the first time and those who switched jobs, the sector choice depends on personal characteristics. In particular, women and people with higher educational attainment or a previous white- collar job are more likely to join the tertiary sector and less likely to join the primary sector. These effects are substantial even if the macroeconomic variables used in conventional structural change theories are controlled. They are also robust in various periods and at more detailed industry levels. Our research suggests that it is important to pay greater attention to the labor composition when mal^ng policy related to economic structural change.

Oxidation Kinetics,Structural Changes and Element Migration during Oxidation Process of Vanadium-titanium Magnetite Ore

The oxidation kinetics, structural changes, and elements migration during the oxidation process of the va- nadium-titanium magnetite （VTM） ore were analyzed. Kinetics analysis indicated that the oxidation process was con- trolled by diffusion control and could be divided into interface diffusion and lattice diffusion with apparent activation energy of 99.69 kJ/mol and 144.08 kJ/mol in the range of 800--1000℃, respectively. The surface structure changed with the oxidization temperature as follows： dense surface→nano sized sheets→submicron particles→molten particles. The compact structure changed into porous one because of the elements migration and enrichment. Both Fe and Ti elements migrated in the opposite direction during the oxidation process. The V etement in the raw ore stably existed in the form of V^5＋ state, some vanadium migrated and occupied the tetrahedral sites of the hematite during the oxidation process.

Structural Changes in the Renminbi Exchange Rate Mechanism

This paper examines structural changes in China s exchange rate mechanism.For this purpose,we propose a predictive model incorporating three factors that influence the central parity rate:a smoothing factor,a market factor,and a basket factor.We first apply the model to analyze the effects of 12 exchange rate reforms since 2005,treating these reforms as predetermined structural breaks.Among other results,we find that the main impact of introducing a“counter-cyclical factor”is to weaken the role of the basket factor.We estimate structural breaks in data,assuming that the number and dates of breaks are unknown,and we find that,although the majority of estimated breaks occur within the neighborhood of exchange rate reforms,there are breaks due to other external shocks such as the escalation of the China-US trade conflict in May 2019.It is suggested that our model may be used to guide future currency reforms in China.

Modified Testing for Structural Changes in Autoregressive Processes

In this paper, we consider the problem of detecting for structural changes in the autoregressive processes including AR（p） process. In performing a test, we employ the conventional residual CUSUM of squares test （RCUSQ） statistic. The RCUSQ test is based on the subsampling method introduced by Jach and Kokoszka [J. Methodology and Computing in Applied Probability 25（2004）]. It is shown that under regularity conditions, the asymptotic distribution of the test statistic is the function of a standard Brownian bridge. Simulation results as to AR（1） process and an example of real data analysis are provided for illustration.

The Impacts of the Growth of the Three Industries and Industrial Price Structural Changes on China’s Economic Growth between 1952 and 2019

This paper focuses on the impacts and effects of China’s growth of the three industries and price structural change on the real GDP growth rate.First of all,it presents a new accounting method for decomposing growth rates on the basis of existing accounting method for decomposing growth rates.By using this method,we can identify the impacts and effects of structural changes on the growth rate.The paper uses a new decomposition method to recalculate China’s industry-based real GDP growth rates between 1952 and 2019,focuses on the driving effect of growth of the three industries on the real GDP growth,and the impacts of price structural change on GDP growth rate and the contributin of the growth of the three industries on GDP growth rate.By analysis,this paper shows that between 1952 and 2019 China’s economic growth was mainly driven by the secondary industry,which had contributed to the economic growth by over 50%,the role of the tertiary industry in driving economic growth rose,but that of the secondary industry declined over the time;in the short run,the overall effect of the price structural changes of the three industries has a little impact on the economic growth,but the price change of each industry has strong effects,and the price structural change has signifi cantly changed the effect of the growth of the three industries on the real economic growth;in the long term,the price structural change plays a relatively big hindering effect on economic growth due to the Baumol’s cost disease.

Structural Evolution and Phase Change Properties of C-Doped Ge_2Sb_2Te_5 Films During Heating in Air

We elucidate the importance of a capping layer on the structural evolution and phase change properties of carbondoped Ge2 Sb2 Te5（C-GST） films during heating in air. Both the C-GST films without and with a thin SiO2 capping layer（C-GST and C-GST/SiO2） are deposited for comparison. Large differences are observed between C-GST and C-GST/SiO2 films in resistance-temperature, x-ray diffraction, x-ray photoelectron spectroscopy,Raman spectra, data retention capability and optical band gap measurements. In the C-GST film, resistancetemperature measurement reveals an unusual smooth decrease in resistance above 110℃ during heating. Xray diffraction result has excluded the possibility of phase change in the C-GST film below 170℃. The x-ray photoelectron spectroscopy experimental result reveals the evolution of Te chemical valence because of the carbon oxidation during heating. Raman spectra further demonstrate that phase changes from an amorphous state to the hexagonal state occur directly during heating in the C-GST film. The quite smooth decrease in resistance is believed to be related with the formation of Te-rich GeTe4-n Gen（n = 0, 1） units above 110℃ in the C-GST film. The oxidation of carbon is harmful to the C-GST phase change properties.

On the agricultural growth and structural changes in Suzhou Wuxi Changzhou region

s—Suzhou Wuxi Changzhou Region (Su Xi Chang) is a famous prosperous agricultural region in China. Since the early 1980s agriculture in Su Xi Chang has got constant developed, but its growth rate is lower than the provincial average level of Jiangsu, and its structure has not changed much. Therefore it lost many in the position of agricultural areal division of labour within Jiangsu Province. The authors of this paper suggest that Su Xi Chang agriculture should perform multiple social, economic and ecological functions with the suburban and export oriented farming as the main development direction. It is also necessary to improve management and organization structure for enhancing Su Xi Chang agricultural vitality.

Microwave Drying of Scots Pine Lumber:Structure Changes,Its Effect on Liquid Permeability

Microwave(MW)drying method was adopted to enhance the liquid permeability of Scots pine lumber.Structure changes were characterized by stereoscope microscope,scanned electron microscope(SEM)and transmission electron microscope(TEM)examination.Pore parameters before and after MW treatment were detected by mercury intrusion porosimetry(MIP)method,and the effect of structure changes on liquid permeability were analyzed.As stereoscope microscope,SEM and TEM examination results showed,macro and micro checks mainly developed at intercellcular of tracheids,intercellular of ray parenchyma and tracheid,while these checks extend main along the radial-longitudinal plane.Pit border destruction,aspirated pits’orus translocation and micro-checks in tracheid cell wall were also observed.MIP test shown that pore volume and pore area increased as macro and micro checks generated to form new cavities.Microstructure changes would increase the quantity of pores or enlarge the pore diameter.Liquid flow pathways increased as macro and micro checks generated,aspirated pits reopened to form new pathways;liquid flow efficiency improved as porosity,pore volume and pore diameter increased which facilitated the liquid flow.

Ultrafast structural dynamics using time-resolved x-ray diffraction driven by relativistic laser pulses

Based on a femtosecond laser plasma-induced hard x-ray source with a high laser pulse energy(>100 mJ)at 10 Hz repetition rate,we present a time-resolved x-ray diffraction system on an ultrafast time scale.The laser intensity is at relativistic regime(2×10^(19)W/cm^(2)),which is essential for effectively generating K_(α)source in high-Z metal material.The produced copper K_(α)radiation yield reaches to 2.5×10^(8)photons/sr/shot.The multilayer mirrors are optimized for monochromatizating and two-dimensional beam shaping of Kαemission.Our experiment exhibits its ability of monitoring the transient structural changes in a thin film SrCoO_(2.5)crystal.It is demonstrated that this facility is a powerful tool to perform dynamic studies on samples and adaptable to the specific needs for different particular applications with high flexibility.

A Model-Free Method for Structual Change Detection Multivariate Nonlinear Time Series

In this paper, we apply the recursive genetic programming (RGP) approach to the cognition of a system, and then proceed to the detecting procedure for structural changes in the system whose components are of long memory. This approach is adaptive and model-free, which can simulate the individual activities of the system's participants, therefore, it has strong ability to recognize the operating mechanism of the system. Based on the previous cognition about the system, a testing statistic is developed for the detection of structural changes in the system. Furthermore, an example is presented to illustrate the validity and practical value of the proposed.