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Utility of semivariogram for spatial variation of soil nutrients and the robust analysis of semivariogram

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Journal of Environmental Sciences 2001年第4期13卷 453-458页

作者： Guo, X.-d. Fu, B.-j. ma, k.-m. Chen, L.-d. Department of Systems Ecology Res. Cntr. Eco-Environmental Sci. Chinese Academy of Sciences Beijing 100085 China

The spatial variation of soil nutrients in topsoil (0-20cm) was analyzed using semivariogram in the Zunhua County of Hebei Province, China. The effect on semivariogram with randomly deleted data and k.iged estimates using various reduced sample sizes was also analyzed. The semivariograms of available N, total N, available P, organic matter were best described by a spherical model, except for available k. which best fitted a complex structure of exponential model and linear with sill model. The ratio of nugget to total sample variance ranged from 34.4% to 68.4%, indicating the spatial correlation of tested soil nutrients on a large scale was moderately dependent. Among five soil nutrients, available nitrogen and available phosphorus had the shortest spatial correlation range (5 k. and 5.5 k.), available k.had the longest range (25.5 k.), whereas total nitrogen and organic matter had intermediate spatial correlation range (14.5 k. and 8.5 k.). The semivariograms of available N, total N, available P, and organic matter were insensitive to a 50%-60% reduction in original sampling density, while for available k. it is up to 70%. The estimated spatial distributions of total N by k.iging, under various reduced sample sizes, all correlated significantly (P = 0.001) with those obtained from original data. The results showed that the semivariogram was a relatively robust tool when used in a large region and sufficient spatial variation information could be relained regardless of a higher deletion proportion of the original data. The original sample data could be reduced by k.iging and the estimates showed no loss of spatial information, however, the results may be unreliable unless a clearly identified semivariogram model could be obtained. The results may provide useful information for determining the appropriate sampling densities for these scales of soil survey.

关键词： Correlation methods Data reduction Nitrogen Phosphorus Sampling Soils Surveying

Achieving strength–ductility synergy in novel paramagnetic Fe-based medium-entropy alloys through deep cryogenic deformation

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Rare Metals 2024年第9期43卷 4493-4507页

作者： Hu-Wen ma Yan-Chun Zhao Li Feng Tian-Zeng Liu Zhi-Qi Yu Bo Jin Wang-Chun Duan Peter k.Liaw Dong ma State k.y Laboratory of Advanced Processing and Recycling of Non-Ferrous Metals Lanzhou University of Technology Wenzhou Pump and Valve Engineering Research Institute Lanzhou University of Technology Iron and Steel Research Institute Jiuquan Iron and Steel Corporation Lanzhou Resources and Environment Voc-Tech University Department of materials Science and Engineering The University of Tennessee Neutron Science Center Songshan Lake Materials Laboratory

Cryogenic pre-deformation treatment has been widely used to effectively improve the comprehensive mechanical properties of steels and novel metals. However,the dislocation evolution and phase transformation induced by different degrees of deep cryogenic deformation are not yet fully elucidated. In this study, the effects of multiple cryogenic pre-treatments on the mechanical properties and deformation mechanisms of a paramagnetic Fe63.3Mn14-Si9.1Cr9.8C3.8medium-entropy alloy（MEA） were investigated, leading to the discovery of a pretreated MEA that exhibits exceptional mechanical properties, including a fracture strength of 3.0 GPa, plastic strain of 26.1% and work.hardening index of 0.57. In addition, X-ray diffraction（XRD） and transmission electron microscopy（TEM）analyses revealed that multiple cryogenic pre-deformation treatments significantly increased the dislocation density of the MEA(from 9 × 1015to 4 × 1016m-2after three pretreatments), along with a transition in the dislocation type from predominantly edge dislocations to mixed dislocations（including screw-and edge-type dislocations）. Notably, this pretreated MEA retained its paramagnetic properties（μrk.ng fault energy of the MEA by a factor of approximately four(i.e., from 9.7 to2.6 m J·m-2), thereby activating the synergistic effects of transformation-induced plasticity, twinning-induced plasticity and dislocation strengthening mechanisms. These synergistic effects lead to simultaneous strength and ductility enhancement of the MEA.

关键词： Deep cryogenic transformation Dislocation evolution Iron-based medium-entropy alloys Phase transformation Stack.ng fault energy

Triple-path feature transform network.for ring-array photoacoustic tomography image reconstruction

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Journal of Innovative Optical Health Sciences 2024年第3期17卷 23-40页

作者： Lingyu ma Zezheng Qin Yiming ma Mingjian Sun School of Astronautics Harbin Institute of Technology HarbinHeilongjiang 150000P.R.China

Photoacoustic imaging(PAI)is a noninvasive emerging imaging method based on the photoacoustic effect,which provides necessary assistance for medical *** has the characteristics of large imaging depth and high ***,limited by the equipment cost and reconstruction time requirements,the existing PAI systems distributed with annular array transducers are difficult to tak. into account both the image quality and the imaging *** this paper,a triple-path feature transform network.TFT-Net)for ring-array photoacoustic tomography is proposed to enhance the imaging quality from limited-view and sparse measurement ***,the network.combines the raw photoacoustic pressure signals and conventional linear reconstruction images as input data,and tak.s the photoacoustic physical model as a prior information to guide the reconstruction *** addition,to enhance the ability of extracting signal features,the residual block.and squeeze and excitation block.are introduced into the *** further efficient reconstruction,the final output of photoacoustic signals uses‘filter-then-upsample’operation with a pixel-shuffle multiplexer and a max out *** results on simulated and in-vivo data demonstrate that the constructed TFT-Net can restore the target boundary clearly,reduce back.round noise,and realize fast and high-quality photoacoustic image reconstruction of limited view with sparse sampling.

关键词： Deep learning feature transformation image reconstruction limited-view measurement photoacoustic tomography.

THERmaL DECOMPOSITION BEHAVIOR OF AMMONIUM THIO TUNGSTATE in H_2

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Acta Metallurgica Sinica(English Letters) 1999年第5期12卷 1171-1174页

作者： P. F. Xing , L. F. ma , k. Quan and Y. C. Zhai School of materials and Metallurgy , Northeastern University , Shenyang 110006 , China

The ther m al deco m position mechanism of a m m oniu m thiotungstate of the size of 63 ～75 μmin H2 has been investigated by D T A and X R D methods . The ther m al deco m position activationenergies and the orders of a m m oniu m thiotu ngstate were calculated by means of k.ssinger , Freem an Carroll and Coast Redfern m ethods . It w as also obtained that therm al deco m posi tion is cond ucted according to four reaction equations :( N H4) 2 W S4· H2 O(s) ( N H4) 2 W S4(s) + H2 O(g) W S2(s) + 2 N H3(g) + H2(g) + 2 S(s) + H2 O(g) W S2(s) + 2 N H3(g) + 2 H2 S(g) + H2 O(g) W S2(s) + W(s) + 2 N H3(g) + 2 H2 S(g) + H2 O(g) .

关键词： a m moniu m thiotungstate ther m al deco m position W S2 H2

Uniform decomposition of velocity gradient tensor

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Journal of Hydrodynamics 2024年第1期36卷 24-34页

作者： Chenxi ma Chaoqun Liu Department of mathematics University of Texas at ArlingtonArlingtonTXUSA

In this paper,the principal decomposition of the velocity gradient tensor[∇v]is discussed in 3 cases based on the discriminant∆:∆0 with 3 distinct real eigen values,and∆=0 with 1 or 2 distinct real eigen *** velocity gradient tensor can also be classified as rotation point,which can be decomposed into three parts,i.e.,rotation[R],shear[S]and stretching/compression[SC],and non-rotation point,we defined a new resistance term[L],and the tensor can be decomposed into three parts,i.e.,resistance[L],shear[S]and stretching/compression[SC].Example matric are also displayed to demonstrate the new *** of principal decomposition between 3 different cases,and between Resistance and Liutex will also be discussed.

关键词： Velocity gradient Liutex resistance fluid k.nematics

VOC emitted by biopharmaceutical industries:Source profiles,health risk.,and secondary pollution

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Journal of Environmental Sciences 2024年第1期135卷 570-584页

作者： Jiawei ma Lin Li State k.y Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China National Engineering Laboratory for VOCs Pollution Control material&Technology University of Chinese Academy of SciencesBeijing 101408China

The biopharmaceutical industry contributes substantially to volatile organic compounds(VOCs)emissions,causing growing concerns and social developmental *** study conducted an on-site investigation of the process-based emission of VOCs from three biopharmaceutical *** the work.hops of the three enterprises,26 VOCs were detected,which could be sorted into 4 classes:hydrocarbons,aromatic hydrocarbons,oxygen-containing compounds,and nitrogen-containing *** were the main components of waste gases,accounting for 44.13%-77.85%of the overall ***-based source profiles were compiled for each process unit,with the fermentation and extraction units of tiamulin fumarate being the main source of VOC *** heptanone,vinyl acetate,diethylamine,propylene glycol methyl ether(PGME),and benzene were screened as priority pollutants through a fuzzy comprehensive evaluation *** level concentration simulation results of the Gauss plume diffusion model demonstrated that the diffusivity of VOCs in the atmosphere was relatively high,indicating potential non-carcinogenic and carcinogenic risk. 1.5-2 k. ***,the process-based formation potentials of ozone and secondary organic aerosols(SOAs)were determined and indicated that N-methyl-2-pyrrolidone,dimethyl heptanone,and PGME should be preferentially controlled to reduce the ozone formation potential,whereas the control of benzene and chlorobenzene should be prioritized to reduce the generation of *** results provide a basis for understanding the characteristics of VOC emission by biopharmaceutical industries and their diffusion,potentially allowing the development of measures to reduce health risk. and secondary pollution.

关键词： Biopharmaceutical Volatile organic compound Priority pollutant Exposure risk Secondary pollution

Deterministic and Robust Volt-var Control Methods of Power System Based on Convex Deep Learning

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 719-729页

作者： Qing ma Changhong Deng the School of Electrical Engineering and Automation Wuhan UniversityWuhanChina

Volt-var control(VVC)is essentially a non-convex optimization problem due to the non-convexity of power flow(PF)constraints,resulting in the difficulty in obtaining the optimum without convexity *** existing second-order cone method for the convexity conversion often leads to a sharp increase in PF constraints and optimization variables,which in turn increases the optimization difficulty or even leads to optimization *** paper first proposes a deterministic VVC method based on convex deep learning power flow(DLPF).This method uses the input convex neural network.ICNN)to establish a single convex mapping between state parameters and node voltage to complete the convexity conversion while the optimization variables only correspond to reactive power equipment,which can ensure the global optimum with extremely fast computation *** cope with the impact brought by the uncertainty of distributed energy and omit the additional worst scenario search of traditional robust VVC,this paper proposes robust VVC method based on convex deep learning interval power flow(DLIPF),which continues to adopt ICNN to establish another convex mapping between state parameters and node voltage *** DLIPF with DLPF,this method decreases the modeling and optimization difficulty of robust VVC *** results on 30-bus,118-bus,and 200-bus systems prove the correctness and rapidity of the proposed methods.

关键词： Volt-var control convexity conversion convex deep learning power flow

Copper slag assisted cok. reduction of phosphogypsum for sulphur dioxide preparation

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Chinese Journal of Chemical Engineering 2024年第1期65卷 43-53页

作者： Dong ma Qinhui Wang State k.y Laboratory of Clean Energy Utilization Institute for Thermal Power EngineeringZhejiang UniversityHangzhou 310027China

The reduction of phosphogypsum(PG)to lime slag and SO_(2)using cok. can effectively alleviate the environmental problems caused by ***,the PG decomposition temperature remains high and the product yield remains *** adding additives,the decomposition temperature can be further reduced and PG decomposition rate and product yield can be ***,the use of current additives such as Fe_(2)O_(3)and SiO_(2)brings the problem of increasing economic ***,it is proposed to use solid waste copper slag(CS)as a new additive to reduce PG to prepare SO2,which can reduce the cost and meet the environmental benefits at the same *** effects of proportion,temperature and thermostatic time on PG decomposition are investigated by experimental and k.netic analysis combined with FactSage thermodynamic calculations to optimize the roasting ***,the reaction mechanism is *** is found that adding CS to the cok. and PG system can increase the rate of PG decomposition and SO_(2)yield while lowering the PG decomposition *** example,when the CS/PG mass ratio increases from 0 to 1,PG decomposition rate increases from 83.38%to 99.35%,SO_(2)yield increases from 78.62%to 96.81%,and PG decomposition temperature decreases from 992.4℃to 949.6℃.The optimal reaction parameters are CS/PG mass ratio of 1,Cok./PG mass ratio of 0.06 at 1100℃for 20 min with 99.35%PG decomposition rate and 96.81%SO_(2) *** process proceeds according to the following reactions:2CaSO_(4)+ 0.7C + 0.8Fe_(2)SiO_(4)→0.8Ca_(2)SiO_(4)+ 0.2Ca_(2)Fe_(2)O_(5)+ 0.4Fe_(3)O_(4)+2SO_(2)+ 0.7CO_(2)Finally,a process for decomposing PG with cok. and CS is proposed.

关键词： Phosphogypsum Sulfur dioxide Copper slag Fluidized-bed Reduction Waste treatment

A review of recent advances in the effects of surface and interface properties on marine propellers

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Friction 2024年第2期12卷 185-214页

作者： manfu ZHU Liran ma State k.y Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing 100084China

marine propellers are important propulsion devices for both surface ships and underwater *** severe environmental problems have required further performance enhancement for ***,traditional methods to improve propeller performances through geometrical and structural optimizations have been extensively investigated,while the underlying mechanisms of the effects of surface and interface properties on marine propellers are still far from being fully *** paper presented a comprehensive review of recent advances in the effects of surface and interface properties,such as surface roughness and surface wettability,on marine propellers with an emphasis on the significant improvements in both hydrodynamic and cavitation performances,hoping to arouse more in-depth investigations in the field of surface/interface science and technologies on marine propellers,and also promote the state-of-the-art technologies,such as superlubricity technology,into practical applications.

关键词： marine propellers hydrodynamics cavitation surface roughness surface wettability