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Acta Mechanica Solida Sinica 2012年第2期25卷 186-196页

作者： Guobin Gong Xiaoxiong zha jun Wei Civil and Environmental Engineering Graduate School in ShenzhenHarbin Institute of TechnologyHIT campusUniversity TownXiliNanshan DistrictShenzhen 518055China (2 School of Civil Engineering Central Sourh UniversityChangsha 410004China

Three dimensional （3D） DEM （discrete element method） simulations of drained triaxial compression and plane strain tests are presented for both dense and loose assemblies of polydisperse spheres using a periodic cell. In the work reported, drained tests were modelled by deforming the samples under constant mean stress conditions. The drained behaviour is shown to be qualitatively similar to published physical experimental results. The Bishop＇s formula for the estimation of the intermediate principal stress is evaluated. The existence of critical density is shown to be independent of initial packing densities and strain conditions. Different failure criteria have been compared based on the DEM simulation results, and the Lade criterion is found to be the most appropriate one. A new microscopic fabric parameter is introduced to give insight to structural anisotropy under general 3D fabric conditions. It is found that two parameters characterize the evolution of the stress and fabric respectively independent of strain conditions.

关键词： DEM simulations drained constant mean stress failure criteria fabric

Effect of Working Position on Vertical Motion Straightness of Open Hydrostatic Guideways in Grinding Machine

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Chinese Journal of Mechanical Engineering 2017年第1期30卷 46-52页

作者： zha jun WANG Zhiwei XUE Fei CHEN Yaolong State Key Laboratory for Manufacturing Systems Engineering Xi 'an Jiaotong University Xi 'an 710049 China College of Mechanical and Electronic Engineering Shandong University of Science and Technology Qingdao 266590 China

Hydrostatic guideways have various applications in precision machine tools due to their high motion accuracy. The analysis of motion straightness in hydrostatic guideways is generally ignoring the external load on the slider. A variation force also exists, caused by the different working positions, together with the dead load of the slider and that of other auxiliary devices. The effect of working position on vertical motion straightness is investigated based on the equivalent static model, considering the error averaging effort of pressured oil film in open hydrostatic guideways. Open hydrostatic guideways in LGF1000 are analyzed with this approach. The theoretical results show that the slider has maximum vertical motion straightness when the working position is closer the guiderail of Y axis. The vertical motion straightness reaches a minimum value as the working position is located at the center of the two guiderails on the Y axis. The difference between the maximum and minimum vertical motion straightness is 34.7%. The smaller vertical motion straightness is attributed to the smaller spacing of the two pads centers, along the Y direction. The experimental results show that the vertical motion straightness is 4.15 μm/1200 mm, when the working position is located in the middle of the Xbeam, and 5.08 pro/1200 mm, when the working position is approaching the Y guiderails, denoting an increase of 18.3%. The changing trends of the measured results validate the correctness of the theoretical model. The research work can be used to reveal the variation law of accuracy of the open hydrostatic guideways, under different working positions, to predict the machining precision, and provides the basis for an error compensation strategy for gantry type grinding machines.

关键词： open hydrostatic guideways error averaging vertical motion straightness working position

Optimized damping for LCL filters in three-phase voltage source inverters coupled by power grid

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Journal of Modern Power Systems and Clean Energy 2017年第4期5卷 642-651页

作者： Meng HUANG Jianjun SUN Yu peng Xiaoming zha Wuhan University WuhanChina Wuhan Electric Power Technical College WuhanChina

The application of LCL filters has become popular for inverters connected to the power grid due to their advantages in harmonic current reductions. However,the power grid in a distribution system is non-ideal, presenting itself as a voltage source with significant impedance. This means that an inverter using an LCL filter may interact with other grid-connected inverters via the nonideal grid. In this paper, damping optimization of LCLfilters to reduce this interaction is studied for a three-phase voltage source inverter(VSI). Simulation results show that resonant oscillation occurs in a distributed power grid, even if the VSI with an LCL filter is well designed for standalone applications. A small-signal analysis is performed to predict this stability problem and to locate the boundary of the instability using an impedance approach. Based on these analytical results, optimized damping of the LCLfilter can be designed. The oscillation phenomena and optimized damping design are verified by simulations and experimental measurements.

关键词： LCL filter Three-phase voltage source inverter Non-ideal power grid Optimized design Interacting converters

Simulation of dual transponder carrier ranging measurements

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第10期10卷 1395-1403页

作者： Xiang-yu zha Xiao-jun JIN Zhong-he JIN Department of lnformation Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

The most dominant error source for microwave ranging is the frequency instability of the oscillator that generates the carrier phase signal. The oscillator noise is very difficult to filter due to its extremely low frequency. A dual transponder carrier ranging method can effectively minimize the oscillator noise by combing the reference phase and the to-and-fro measurement phase from the same single oscillator. This method does not require an accurate time tagging system, since it extracts phases on the same satellite. This paper analyzes the dual transponder carrier ranging system by simulation of the phase measurements with comprehensive error models. Both frequency domain and time domain noise transfer characteristics were simulated to compare them with dual one-way ranging. The simulation results in the two domains conformed to each other and demonstrated that a high level of accuracy can also be achieved by use of the dual transponder carder ranging system, with relatively simple instruments.

关键词： Dual transponder carrier ranging Dual one-way ranging Oscillator noise Transfer characteristic

Constructing p, n-forms from p-forms via the Hodge star operator and the exterior derivative

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Communications in Theoretical Physics 2020年第6期72卷 97-105页

作者： jun-Jin peng School of Physics and Electronic Science Guizhou Normal UniversityGuiyangGuizhou 550001China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyangGuizhou 550001China

In this paper,we aim to explore the properties and applications on the operators consisting of the Hodge star operator together with the exterior derivative,whose action on an arbitrary p-form field in n-dimensional spacetimes makes its form degree remain *** operations are able to generate a variety of p-forms with the even-order derivatives of the *** do this,we first investigate the properties of the operators,such as the Laplace–de Rham operator,the codifferential and their combinations,as well as the applications of the operators in the construction of conserved *** the basis of two general p-forms,then we construct a general n-form with higher-order ***,we propose that such an n-form could be applied to define a generalized Lagrangian with respect to a p-form field according to the fact that it includes the ordinary Lagrangians for the p-form and scalar fields as special cases.

关键词： p-form Hodge star Laplace–Beltrami operator Lagrangian for p-form

Persistent alterations in gray matter in COVID-19 patients experiencing sleep disturbances:a 3-month longitudinal study

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Neural Regeneration Research 2025年第10期20卷 3013-3024页

作者： Kaixuan Zhou Gaoxiong Duan Ying Liu Bei peng Xiaoyan Zhou Lixia Qin Lingyan Liang Yichen Wei Qingping zhang Xiaocheng Li Haixia Qin Yinqi Lai Yian Lu Yan zhang Jiazhu Huang Jinli Huang Yinfei Ouyang Bolin Bin Mingming zhao jun Liu Jianrong Yang Demao Deng Guangxi Key Laboratory of Special Biomedicine School of MedicineGuangxi UniversityNanningGuangxi Zhuang Autonomous RegionChina Department of Radiology the People’s Hospital of Guangxi Zhuang Autonomous RegionGuangxi Academy of Medical SciencesNanningGuangxi Zhuang Autonomous RegionChina Department of Sleep Medicine the People’s Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxi Zhuang Autonomous RegionChina Department of Radiology The Second Xiangya HospitalCentral South UniversityChangshaHunan ProvinceChina Guangxi Clinical Research Center for Sleep Medicine the People’s Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxi Zhuang Autonomous RegionChina

Sleep disturbances are among the most prevalent neuropsychiatric symptoms in individuals who have recovered from severe acute respiratory syndrome coronavirus 2 *** studies have demonstrated abnormal brain structures in patients with sleep disturbances who have recovered from coronavirus disease 2019(COVID-19).However,neuroimaging studies on sleep disturbances caused by COVID-19 are scarce,and existing studies have primarily focused on the long-term effects of the virus,with minimal acute phase *** a result,little is known about the pathophysiology of sleep disturbances in the acute phase of *** address this issue,we designed a longitudinal study to investigate whether alterations in brain structure occur during the acute phase of infection,and verified the results using 3-month follow-up data.A total of 26 COVID-19 patients with sleep disturbances(aged 51.5±13.57 years,8 women and 18 men),27 COVID-19 patients without sleep disturbances(aged 47.33±15.98 years,9 women and 18 men),and 31 age-and gender-matched healthy controls(aged 49.19±17.51 years,9 women and 22 men)were included in this *** COVID-19 patients with sleep disturbances were included in a longitudinal *** found that COVID-19 patients with sleep disturbances exhibited brain structural changes in almost all brain *** cortical thicknesses of the left pars opercularis and left precuneus were significantly negatively correlated with Pittsburgh Sleep Quality Index ***,we observed changes in the volume of the hippocampus and its subfield regions in COVID-19 patients compared with the healthy *** 3-month follow-up data revealed indices of altered cerebral structure(cortical thickness,cortical grey matter volume,and cortical surface area)in the frontal-parietal cortex compared with the baseline in COVID-19 patients with sleep *** findings indicate that the sleep disturbances patients had altered morphology in the cortical an

关键词： brain structure cortical gray matter volume cortical surface area cortical thickness hippocampus magnetic resonance imaging Pittsburgh Sleep Quality Index severe acute respiratory syndrome coronavirus 2 infections sleep disturbances sub-cortical volume

A nonparametric distance function approach with endogenous direction for estimating marginal abatement costs of CO_(2) emissions

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Journal of Management Science and Engineering 2022年第2期7卷 330-345页

作者： Fei Wu Dan-jun Ji Dong-Lan zha De-Qun Zhou peng Zhou College of Economics and Management&Research Centre for Soft Energy Science Nanjing University of Aeronautics and AstronauticsNanjing211106China School of Economics and Management&Institute for Energy Economics and Policy China University of PetroleumQingdao266580China

The directional distance function(DDF)framework has been widely used to estimate the marginal abatement cost(MAC)of CO_(2)emissions to support decision-making in environmental sustainability and climate change *** the use of DDF,an important task is mapping evaluated entities towards a realistic production technology *** study develops a new nonparametric approach for estimating the MAC of CO_(2)*** approach incorporates the optimal endogenous direction into an enhanced environmental production technology and has three ***,it avoids the arbitrariness in mapping ***,it captures the heterogeneity in optimization paths across different decision-making units(DMUs).Third,it generates more reliable benchmarks for estimating MAC by constructing an environmental technology frontier that is consistent with the material balance *** apply the approach to study China's thermal power industry and find clear heterogeneity in MACs and optimization paths at the province *** results on the optimal endogenous directions show that the DMUs prefer to increase both desirable output and CO_(2)emissions when CO_(2)emissions are *** with other approaches reveal that arbitrarily mapping exogenous directions and technology representations are likely to generate distorted and unrealistic MACs.

关键词： Marginal abatement cost Carbondioxideemissions Directional distance function Weak disposability Dataenvelopment analysis

SOX4 contributes to TGF-β-induced epithelialemesenchymal transition and stem cell characteristics of gastric cancer cells

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Genes & Diseases 2018年第1期5卷 49-61页

作者： Xudong peng Guangyi Liu Hongxia peng Anqi Chen Lang zha Ziwei Wang Gastrointestinal Surgical Unit The First Affiliated Hospital of Chongqing Medical UniversityChongqing400000China Department of General Surgery The First People’s HospitalYibinSichuan644000 China

SOX4 is highly expressed in gastric cancer(GC)and is associated with tumor grade,metastasis and prognosis,however the mechanism is not *** report herein that SOX4 was upregulated and overexpression of SOX4 was associated with increased expression of the markers of Epithelialemesenchymal transition(EMT)and stemness in clinic patient *** vitro,overexpression of SOX4 promoted the invasion as showed by Transwell assay and stemness of GC cells as assessed by sphere formation assay,which was suppressed by silencing SOX4 with *** studies showed that SOX4 up-regulated the expression of EMT transcription factors Twist1,snail1 and zeb1 and stemness transcription factors SOX2 and OCT4,and promoted the nuclear translocation of β-***,we revealed that TGF-β treatment significantly up-regulated the expression of SOX4 and silencing SOX4 reversed TGF-β induced invasion and sphere formation ability of GC ***,we showed that SOX4 promoted the lung metastasis and tumor formation ability of gastric cancer cells in nude *** results suggest that SOX4 is a target TGF-β signaling and mediates TGF-β-induced EMT and stem cell characteristics of GC cells,revealing a novel role of TGF-β/SOX4 axis in the regulation of malignant behavior of GC.

关键词： Epitheliale mesenchymal transition Gastric cancer SOX4 Stemness TGF-β

Amine-Actuated Catalyst Switch for One-Pot Synthesis of Ether-Ester Type Block Copolymers

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Chinese Journal of Polymer Science 2024年第12期42卷 1925-1932,I0008页

作者： Hong Qiu peng-Fei zhang jun-peng zhao Faculty of Materials Science and Engineering South China University of TechnologyGuangzhou 510640China

Organocatalysis has shown special potency for simplifying the construction of complex polymer *** are reporting here a one-pot synthetic pathway using amine as a selectivity-switching agent in the two-component catalytic system consisting of triethylborane(Et_(3)B)and a phosphazene *** first modelled the interactions of a variety of amines with Et_(3)B by density functional theory *** results indicate that the aliphatic diamines comprising both primary and tertiary amino groups,capable of forming stable intramolecular hydrogen bonds,undergo the strongest complexation with Et_(3)***,experimental results demonstrate that the addition of such amines promptly actuates the in situ selectivity switch from Lewis pair-catalyzed ring-opening polymerization(ROP)of epoxide(propylene oxide,n-butylglycidyl ether,or glycidyl phenyl ether)to organobase-catalyzed ROP ofδ-valerolactone,allowing one-pot continuous synthesis of ether-ester type block *** thus exploited the noncovalent interaction between amine and Et_(3)B to refine the catalyst switch strategy by exempting it from loading of extra catalyst.

关键词： Ring-opening polmerization Block copolymers Organocatalysis

Numerical investigation and optimisation of heat transfer performance in a vertical sinter cooling packed bed using Taguchi and ANOVA methods

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Journal of Iron and Steel Research International 2020年第8期27卷 898-912页

作者： jun-peng Fu Jiu-ju Cai Department of Thermal Engineering SEP Key Laboratory of Eco-IndustrySchool of MetallurgyNortheastern UniversityShenyang 110819LiaoningChina

The Taguchi and analysis of variance (ANOVA) methods were applied to investigate the effects of the structural and operational parameters on the heat transfer performance of a vertical sinter cooling packed bed. The analysed parameters were the gas flow rate, the air inlet temperature, the sinter inlet temperature, the cooling bed diameter and the cooling bed height, all of which contain three levels. The purpose was to improve the heat transfer performance of a vertical sinter cooling bed. A numerical analysis model was established to assess the heat transfer performance with respect to the varying parameters and their different levels. This mathematical model was validated by using data from practical industrial processes. The Taguchi method for the L27 (35) orthogonal design experiment was selected to evaluate the impacts of the design parameters on the heat transfer performance and to acquire the optimum combination of parameters. The analysis of variance was applied to assess the impact weights and the order of significance of the design parameters. The results show that the sinter inlet temperature and cooling bed diameter have great influences and impact the exergy of the wasted heat recovery by 61.65% and 23.31%, respectively. However, the gas flow rate and the air inlet temperature have small effects on the response. Furthermore, the air and sinter inlet temperatures have the most significant impacts on the efficiency of heat transfer by 68.83% and 23.31%, respectively. The optimal parameter combination (A1B1C3D3E3) was obtained, and the optimal results were validated by confirmation tests.

关键词： Vertical sinter packed bed Wasted heat recovery Taguchi method Analysis of variance(ANOVA) Gas–solid heat transfer