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

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Journal of Integrative Agriculture 2024年第5期23卷 1763-1773页

作者： Xiangyang zhang yumei zhang Shenggen Fan College of Economics and Management China Agricultural UniversityBejing 100083China Academy of Global Food Economics and Policy China Agricultural UniversityBejing 100083China

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 *** a result,land productivity,nutrient supply,and carbon emissions have *** to reallocate limited farmland among crops to achieve the multiple goals of agrifood systems becomes an important *** 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 *** results reveal that the growth within crops is still the primary driver in land productivity and nutrition supply and the reduction in carbon ***,structural change also plays various roles at different *** 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 *** crop structure was relatively stable,and their effects were modest from 2010 to *** 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 *** results suggest that strategies for crop structural change should comprehensively consider its multiple impacts,aiming to achieve co-benefits while minimizing trade-offs.

关键词： crop structural change land productivity nutrition carbon emissions

Kernel Estimation of Truncated Volterra Filter Model Based on DFP Technique and Its Application to Chaotic Time Series Prediction

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Chinese Journal of Electronics 2019年第1期28卷 127-135页

作者： zhang yumei BAI Shulin LU Gang WU Xiaojun Key Laboratory of Modern Teaching Technology Ministry of EducationShaanxi Normal University School of Computer Science Shaanxi Normal University School of Electronics and Information Northwestern Polytechnical University

In order to overcome some problems caused by improper parameters selection when applying Least mean square(LMS), Normalized LMS(NLMS) or Recursive least square(RLS) algorithms to estimate coefficients of second-order Volterra filter, a novel DavidonFletcher-Powell-based Second-order Volterra filter(DFPSOVF) is proposed. Analysis of computational complexity and stability are presented. Simulation results of system parameter identification show that the DFP algorithm has fast convergence and excellent robustness than LMS and RLS algorithm. Prediction results of applying DFPSOVF model to single step predictions for Lorenz chaotic time series illustrate stability and convergence and there have not divergence problems. For the measured multiframe speech signals, prediction accuracy using DFPSOVF model is better than that of Linear prediction(LP).The DFP-SOVF model can better predict chaotic time series and the real measured speech signal series.

关键词： Chaos Davidon-Fletcher-Powell algorithm Prediction model Second-order Volterra filter Speech signal

FMR-GNet: Forward Mix-Hop Spatial-Temporal Residual Graph Network for 3D Pose Estimation

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Chinese Journal of Electronics 2024年第6期33卷 1346-1359页

作者： Honghong YANG Hongxi LIU yumei zhang Xiaojun WU Key Laboratory of Modern Teaching Technology Ministry of Education Shaanxi Normal University Key Laboratory of Intelligent Computing and Service Technology for Folk Song Ministry of Culture and Tourism School of Computer Science Shaanxi Normal University

Graph convolutional networks that leverage spatial-temporal information from skeletal data have emerged as a popular approach for 3D human pose estimation. However, comprehensively modeling consistent spatialtemporal dependencies among the body joints remains a challenging task. Current approaches are limited by performing graph convolutions solely on immediate neighbors, deploying separate spatial or temporal modules, and utilizing single-pass feedforward architectures. To solve these limitations, we propose a forward multi-scale residual graph convolutional network(FMR-GNet) for 3D pose estimation from monocular video. First, we introduce a mix-hop spatialtemporal attention graph convolution layer that effectively aggregates neighboring features with learnable weights over large receptive fields. The attention mechanism enables dynamically computing edge weights at each layer. Second,we devise a cross-domain spatial-temporal residual module to fuse multi-scale spatial-temporal convolutional features through residual connections, explicitly modeling interdependencies across spatial and temporal domains. Third, we integrate a forward dense connection block to propagate spatial-temporal representations across network layers, enabling high-level semantic skeleton information to enrich lower-level features. Comprehensive experiments conducted on two challenging 3D human pose estimation benchmarks, namely Human3.6M and MPI-INF-3DHP, demonstrate that the proposed FMR-GNet achieves superior performance, surpassing the most state-of-the-art methods.

关键词： Location awareness Three-dimensional displays Correlation Graph convolutional networks Fuses Aggregates Pose estimation Semantics Benchmark testing Skeleton

Optimizing environmental insulation thickness of buildings with CHP-based district heating system based on amount of energy and energy grade

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Frontiers in Energy 2022年第4期16卷 613-628页

作者： yumei zhang Pengfei JIE Chunhua LIU Jing LI School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Engineering and Technology R&D Center of Clean Air Conditioning in Colleges of Shandong Shandong Huayu University of TechnologyDezhou 253000China China Environmental Resources Technology Co. LtdBeijing 100012China

The increase of insulation thickness(IT)results in the decrease of the heat demand and heat medium temperature.A mathematical model on the optimum environmental insulation thickness(OEIT)for minimizing the annual total environmental impact was established based on the amount of energy and energy grade ***,a case study was conducted based on a residential community with a combined heat and power(CHP)-based district heating system(DHS)in Tianjin,***,the effect of IT on heat demand,heat medium temperature,exhaust heat,extracted heat,coal consumption,carbon dioxide(CO_(2))emissions and sulfur dioxide(SO_(2))emissions as well as the effect of three types of insulation materials(i.e.,expanded polystyrene,rock wool and glass wool)on the OEIT and minimum annual total environmental impact were *** results reveal that the optimization model can be used to determine the *** the OEIT of expanded polystyrene,rock wool and glass wool is used,the annual total environmental impact can be reduced by 84.563%,83.211%,and 86.104%,*** can be found that glass wool is more beneficial to the environment compared with expanded polystyrene and rock wool.

关键词： optimum environmental insulation thickness heat medium temperature energy grade extracted heat exhaust heat

Determination of physical properties for the mixtures of [BMIM]Cl with different organic solvents

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Chinese Journal of Chemical Engineering 2015年第5期23卷 804-811页

作者： Hina Saba Xinjun Zhu Ye Chen yumei zhang State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua University Department of Material and Engineering Luoyang Institute of Science and Technology

Physical properties including refractive index, density, viscosity and conductivity for binary mixtures of l-butyl- 3-methyl imidazolium chloride （[BMIM]CI） and different organic solvents at 298.15 K have been investigated. Ex- cess molar volumes have been calculated and obtained data has been fitted by the Redlich-Kister equation. The density and refractive index were found to increase with increasing concentration of [BMIM]CI, however, excep- tions do exist as in the case of dimethyl sulfoxide （DMSO）/[BMIM]CI. For DMSO/[BMIM]CI, the density decreases with increasing concentration. The addition of different organic solvents was able to disrupt the interactions within mixtures, leading to free mobility of ions. The free mobility of ions has been found to enhance conductivity and decrease viscosity to varying extents in all mixtures studied. It has been observed that solubility parameters, dielectric constants and composition of the solvents used play a vital role in determining the resultant properties. The data obtained will play an important role in understanding the effect of the addition of organic solvents in ILs to enhance their applicability.

关键词： Ionic liquid Viscosity Conductivity Refractive index Density Binary mixtures Organic solvents

A New Phase Transition in Dense Vortices

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Chinese Physics Letters 1995年第5期12卷 293-296页

作者： CHEN Zhijian zhang yumei XU Bowei Department of Physics Shanghai Jiaotong UniversityShanghai 200030 Department of Physics Tongji UniversityShanghai 200092

An improved XY model is adopted for the vortices in the *** the case of high density,the fugacity should be modified by the higher *** use of the variational effective potential,we analyze the discontinuous phase tran... 详细信息

关键词： temperature Transition harmonics

Multi-Traffic Targets Tracking Based on an Improved Structural Sparse Representation with Spatial-Temporal Constraint

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Chinese Journal of Electronics 2022年第2期31卷 266-276页

作者： YANG Honghong SHANG Junchao LI Jingjing zhang yumei WU Xiaojun Key Laboratory of Modern Teaching Technology Ministry of EducationShaanxi Normal University School of Computer Science Shaanxi Normal University School of Journalism and Communication Shaanxi Normal University

Vehicles or pedestrians tracking is an important task in intelligent transportation system. In this paper, we propose an online multi-object tracking for intelligent traffic platform that employs improved sparse representation and structural constraint. We first build the spatial-temporal constraint via the geometric relations and appearance of tracked objects, then we construct a robust appearance model by incorporating the discriminative sparse representation with weight constraint and local sparse appearance with occlusion analysis. Finally, we complete data association by using maximum a posteriori in a Bayesian framework in the pursuit for the optimal detection estimation. Experimental results in two challenging vehicle tracking benchmark datasets show that the proposed method has a good tracking performance.

关键词： road vehicles multiobject tracking target tracking improved structural sparse representation object tracking Bayes methods image representation robust appearance model object detection data association pedestrians intelligent traffic platform optimisation road traffic geometric relations local sparse appearance optimal detection estimation spatial-temporal constraint intelligent transportation system multitraffic targets tracking weight constraint pedestrians tracking Bayesian framework occlusion analysis intelligent transportation systems

Hidden Phase Space Reconstruction: A Novel Chaotic Time Series Prediction Method for Speech Signals

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Chinese Journal of Electronics 2018年第6期27卷 1221-1228页

作者： LI Jingjing zhang Qijin zhang yumei WU Xiaojun WANG Xiaoming SU Yuping Key Laboratory of Modern Teaching Technology Ministry of Education Shaanxi Normal University School of Computer Science Shaanxi Normal University

Speech signals are nonlinear chaotic time series. This paper proposes a novel speech signal nonlinear prediction model with the hidden phase space reconstruction method. The parameters, embedding dimension m, time delay τ and model structure are solved simultaneously, breaking the restriction of phase space, which needs to be reconstructed before modeling for the existing prediction method. Subsequently, an explicit speech signal prediction model is generated. Meanwhile, the introduction of the frame length parameter k effectively extends the prediction length. Experimental results show that the values of m and τ solved by the proposed method are consistent with the values addressed by the Cao method and mutual information method, respectively. In addition, the optimal value of k is further discussed. The prediction results obtained using the proposed model are more accurate than those of linear prediction coding, the radial basis function neural network model and the long short-term memory network.

关键词： Speech signal Hidden phase space reconstruction Chaotic time series prediction Frame length parameter

Experimental research on hydrophilic characteristics of natural soft rock at high stress state

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International Journal of Mining Science and Technology 2015年第3期25卷 489-495页

作者： Guo Hongyun Lei Xiangyang zhang yumei Yang Guoxing Niu zhang The Engineering Design Research Institute of Equipment of PLA Astronaut Center of China China Taiyuan Satellite Launch Center

In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks(ITSWADSR) was utilized to analyze the hydrophilic behaviors of natural soft rock at high stress state. Combining X-ray diffraction and mercury injection test, main influencing factors on hydrophilic characteristics were studied. According to the results, it could be concluded as the following:(1) the effective porosity, and the content of illite, illite/smectite formation(S = 5%) and kaolinite have positive correlation with the water absorption capacity of rock; meanwhile, the initial moisture content, fractal dimension of effective pores, illite/smectite formation(S = 30%) and chlorite present negative correlation;(2) among the positive factors, the ascending order is kaolinite, illite/smectite formation(S = 5%) and illite;(3) the descending order among the negative factors are chlorite, illite/smectite formation(S = 30%) and fractal dimension of the effective pores;(4) influence of effective porosity on the pressurized water absorbing capacity of rock is minimal, while it is maximal in the process of no pressurized water absorption.

关键词： Natural soft rock Water absorption tests X-ray diffraction Mercury injection test Hydrophilic characteristics