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Closed-loop Control Using High Power Hexapole Magnetic Tweezers for 3D Micromanipulation

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Journal of Bionic Engineering 2020年第1期17卷 113-122页

作者： Xiao zhang louis WRogowski Min Jun Kim Department of Mechanical Engineering Southern Methodist UniversityDallasTX 75275USA

This paper presents the design,modeling,integration,and application of 3D printed high power hexapole magnetic tweezers for 3D micromanipulation *** sharp-tipped magnetic poles were configured with electromagnetic coils and mounted on 3D printed magnetic yokes to form a tilted Cartesian coordinate system for actuation.A closed loop control algorithm was developed to automatically manipulate external power supplies connected to the magnetic tweezers,by using 3D positional information obtained from real-time image processing *** compared against other designs of magnetic tweezers,our system has a larger working space and can generate higher magnetic field *** allows for more diverse applications regarding small scale manipulation,including cell manipulation and cell *** and analytics explained in this paper demonstrate the closed-loop manipulation of microswimmers can provide a magnetic force as high as 800 pN while maintaining a positional error below 4μm in 3D and 1.6μm in *** the desired location as the control input,the microswimmers investigated were able to achieve arbitrary 2D and 3D *** also show that the implemented hexapole magnetic tweezers have adequate power to control microswimmers in Newtonian fluid *** system will later be optimized and deployed to control microswimmers in non-Newtonian fluid environments.

关键词： magnetic tweezers micromanipulation magnetic gradient control 3D motion control microswimmers

Fabrication of lithium silicates from zeolite for CO2 capture at high temperatures

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Journal of Energy Chemistry 2019年第6期28卷 81-89页

作者： Yu zhang Yanshan Gao Benoit louis Qiang Wang Weiran Lin College of Environmental Science and Engineering Beijing Forestry UniversityBeijing 100083China ICPEES - Institut de Chimie et Procedes pour l’energie l’Environnement et la SanteUMR 7515 CNRS - Universite de Strasbourg67087 StrasbourgFrance Beijing Research Institute of Chemical Industry SINOPECBeijing 100013China

Li4Si O4 has been regarded as one of the most promising high-temperature CO2 ***,for practical applications,its CO2sorption kinetics,cycling stability and sorption properties at lower temperatures or lower CO2 concentrations have to be *** this contribution,four Li4Si O4 sorbents were synthesized from zeolite precursors MCM-41,MCM-48,TS-1,and *** CO2 uptake,cycling stability and the optimal CO2 sorption conditions were *** the samples,MCM-41-Li4Si O4 showed the best cycling stability at 650°C,with a stable reversible CO2 uptake of 29.1 wt%under 100 vol%CO2 during 20 *** its sorption kinetics and CO2 uptakes at lower temperatures and lower CO2 concentrations need to be *** then demonstrated that the sorption kinetics can be improved by modifying the MCM-41 precursor with metals such as Al,Ti,Ca,and *** Na-MCM-41-Li4Si O4 sample exhibited the highest sorption rate,and reached the equilibrium sorption capacity close to the theoretical value of 36.7 wt%within 20 *** addition,we proved that coating the MCM-41-Li4Si O4with Na2CO3and K2CO3can significantly increase the CO2uptakes at lower temperatures(e.g.550℃)and lower CO2concentrations(10–20 vol%).At 550℃ and under 20 vol%CO2,15 wt%K2CO3-MCM-41-Li4Si O4 and 10 wt%Na2CO3-MCM-41-Li4Si O4 sorbents resulted in a CO2 uptake of 32.2 wt%and 34.7 wt%,respectively,which are much higher than that of MCM-41-Li4Si O4(11.8 wt%).These two sorbents also showed good cycling *** promoiting mechasnim by alkali carbonate coating was discussed by a doubleshell model.

关键词： Li4SiO4 Zeolite Lithium silicate-based CO2 sorbents Global warming

Approximation algorithms for nonnegative polynomial optimization problems over unit spheres

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Frontiers of Mathematics in China 2017年第6期12卷 1409-1426页

作者： Xinzhen zhang Guanglu ZHOU louis CACCETTA Mohammed ALQAHTANI School of Mathematics Tianjin University Tianjin 300072 China Department of Mathematics and Statistics Curtin University Perth Australia

We consider approximation algorithms for nonnegative polynomial optimization problems over unit spheres. These optimization problems have wide applications e.g., in signal and image processing, high order statistics, and computer vision. Since these problems are NP-hard, we are interested in studying on approximation algorithms. In particular, we propose some polynomial-time approximation algorithms with new approximation bounds. In addition, based on these approximation algorithms, some efficient algorithms are presented and numerical results are reported to show the efficiency of our proposed algorithms.

关键词： Approximation algorithm polynomial optimization approximationbound

Synthesis and characterization of novel star-shaped pyridine cored compounds with alternating carbazole and triphenylamine moieties

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Chinese Chemical Letters 2008年第6期19卷 647-650页

作者： Ji Bing Yuan Zhi Guo zhang louis Man Leung Ke Li zhang College of Chemistry and Molecular Sciences Wuhan University Wuhan 430072 China College of Chemical and Environmental Engineering Hubei University of Technology Wuhan 430068 China Department of Chemistry Hong Kong Baptist University Hongkong China

Amorphous 2,4,6-trissubstituted pyridines containing three peripheral carbazole or two triphenylamine and one carbazole moieties, respectively, have been synthesized and characterized. The properties of the compounds are investigated by UV-vis absorption, photoluminescence spectroscopy, thermal analysis as well as cyclic voltammetry. The results show that the compounds have high thermal stability, emit blue light. Also, the compounds possess the HOMO and LUMO energy levels comparable to those of NPB. The effects of different substituents on the electronic properties of the materials have been discussed.

关键词： Star-shaped Carbazole Tdphenylamine Pyridine

Lightweight Multi-scale Convolutional Neural Network for Rice Leaf Disease Recognition

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Computers, Materials & Continua 2023年第1期74卷 983-994页

作者： Chang zhang Ruiwen Ni Ye Mu Yu Sun Thobela louis Tyasi College of Information Technology Jilin Agricultural UniversityChangchun130118China Jilin Province Agricultural Internet of Things Technology Collaborative Innovation Center Changchun130118China Jilin Province Intelligent Environmental Engineering Research Center Changchun130118China Jilin Province Information Technology and Intelligent Agriculture Engineering Research Center Changchun130118China Department of Agricultural Economics and Animal Production University of LimpopoPrivate Bag X 1106Sovenga0727PolokwaneSouth Africa

In the field of agricultural information,the identification and prediction of rice leaf disease have always been the focus of research,and deep learning(DL)technology is currently a hot research topic in the field of pattern *** research and development of high-efficiency,highquality and low-cost automatic identification methods for rice diseases that can replace humans is an important means of dealing with the current situation from a technical *** paper mainly focuses on the problem of huge parameters of the Convolutional Neural Network(CNN)model and proposes a recognitionmodel that combines amulti-scale convolution module with a neural network model based on Visual Geometry Group(VGG).The accuracy and loss of the training set and the test set are used to evaluate the performance of the *** test accuracy of this model is 97.1%that has increased 5.87%over ***,the memory requirement is 26.1M,only 1.6%of the *** results show that this model performs better in terms of accuracy,recognition speed and memory size.

关键词： Rice leaf diseases deep learning lightweight convolution neural networks VGG

Dendritic Morphology Affects the Velocity and Amplitude of Back-propagating Action Potentials

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Neuroscience Bulletin 2022年第11期38卷 1330-1346页

作者： Wu Tian Luxin Peng Mengdi Zhao louis Tao Peng Zou Yan zhang State Key Laboratory of Membrane Biology College of Life SciencesPeking UniversityBeijing 100871China College of Chemistry and Molecular Engineering Synthetic and Functional Biomolecules CenterBeijing National Laboratory for Molecular SciencesKey Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationPeking UniversityBeijing 100871China Center for Quantitative Biology Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijing 100871China PKU-IDG/McGovern Institute for Brain Research Peking UniversityBeijing 100871China Center for Bioinformatics National Laboratory of Protein Engineering and Plant Genetic EngineeringSchool of Life SciencesPeking UniversityBeijing 100871China Peking-Tsinghua Center for Life Sciences Peking UniversityBeijing 100871China Chinese Institute for Brain Research(CIBR) Beijing 102206China Beijing Academy of Artifcial Intelligence Beijing 100084China

The back-propagating action potential(bpAP)is crucial for neuronal signal integration and synaptic plasticity in dendritic *** properties(velocity and amplitude)can be affected by dendritic *** to limited spatial resolution,it has been difficult to explore the specific propagation process of bpAPs along dendrites and examine the influence of dendritic morphology,such as the dendrite diameter and branching pattern,using patch-clamp *** taking advantage of Optopatch,an all-optical electrophysiological method,we made detailed recordings of the real-time propagation of bpAPs in dendritic *** found that the velocity of bpAPs was not uniform in a single dendrite,and the bpAP velocity differed among distinct dendrites of the same *** velocity of a bpAP was positively correlated with the diameter of the dendrite on which it *** addition,when bpAPs passed through a dendritic branch point,their velocity decreased *** to velocity,the amplitude of bpAPs was also positively correlated with dendritic diameter,and the attenuation patterns of bpAPs differed among different *** results from neuron models with different dendritic morphology corresponded well with the experimental *** findings indicate that the dendritic diameter and branching pattern significantly influence the properties of *** diversity among the bpAPs recorded in different neurons was mainly due to differences in dendritic *** results may inspire the construction of neuronal models to predict the propagation of bpAPs in dendrites with enormous variation in morphology,to further illuminate the role of bpAPs in neuronal communication.

关键词： Dendrite Action potential Backpropagation Synaptic integration

Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1216-1230页

作者： Fanzhen Meng Feili Wang louis Ngai Yuen Wong Jie Song Muzi Li Chuanqing zhang Liming zhang College of Science Qingdao University of TechnologyQingdao266033China Department of Earth Sciences The University of Hong KongPokfulamHong KongChina State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China Cooperative Innovation Center of Engineering Construction and Safety Shandong Peninsula Blue Economic Zone Qingdao266033China

The damage of rock joints or fractures upon shear includes the surface damage occurring at the contact asperities and the damage beneath the shear surface within the host *** latter is commonly known as off-fault damage and has been much less investigated than the surface *** main contribution of this study is to compare the results of direct shear tests conducted on saw-cut planar joints and tension-induced rough granite joints under normal stresses ranging from 1 MPa to 50 *** shear-induced off-fault damages are quantified and compared with the optical microscope *** results clearly show that the planar joints slip stably under all the normal stresses except under 50 MPa,where some local fractures and regular stick-slip occur towards the end of the *** post-peak stress drop and stick-slip occur for all the rough *** residual shear strength envelopes for the rough joints and the peak shear strength envelope for the planar joints almost *** root mean square(RMS)of asperity height for the rough joints decreases while it increases for the planar joint after shear,and a larger normal stress usually leads to a more significant decrease or increase in ***,the extent of off-fault damage(or damage zone)increases with normal stress for both planar and rough joints,and it is restricted to a very thin layer with limited micro-cracks beneath the planar joint *** comparison,the thickness of the damage zone for the rough joints is about an order of magnitude larger than that of the planar joints,and the coalesced micro-cracks are generally inclined to the shear direction with acute *** findings obtained in this study contribute to a better understanding on the frictional behavior and damage characteristics of rock joints or fractures with different roughness.

关键词： Planar joint Rough joint Shear behavior Off-fault damage Micro-cracks

Kinematic History and Changes in the Tectonic Stress Regime during the Cenozoic along the Qinling and Southern Tanlu Fault Zones

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Acta Geologica Sinica(English Edition) 1999年第3期73卷 264-274页

作者： zhang Yueqiao Pierre Vergèly Jacques-louis Mercier WANG Yongmin zhang Yong HUANG Dezhi Institute of Geomechanics Chinese Academy of GeologyBeijing 100081China URA-CNRS:Géophysique et Géodynamique Interne Universitéde Parie-SudBatment 509F-91405Orsay-CedexFrance Institute of Geology Bureau of Geology and Mineral Resouces of Anhui ProvinceHefeiChina

Since the mid-late Eocene, North China has been subjected to extensional stress, resulting in the formation and development of basins. The dynamic origin of this crustal extension has long been an issue of debate. This paper presents the results of kinematic analyses of faults obtained from two seperated areas in North China. In the Weihe graben situated on the southernmost margin of the Ordos block, analyses of fault kinematics were coupled with an analysis of the basin's subsidence history. Three successive extensional tectonic phases accompaning the basin's formation and development have been distinguished. The Palaeogene extension was oriented in a WNW-ESE direction; the Neogene extension in a NE-SW direction and the Pliocene-Quaternary extension in a NW-SE direction. Such changes have also been recorded by fault kinematics along the southern Tanlu fault zone. This has been demonstrated by three successive sets of fault striations indicating normal dip slip resulting from NW-SE extension, then left-lateral slip with a normal component resulting from NE-SW extension, and right-lateral slip with a minor normal component, respectively. The kinematic history of faults and their chronological evolution indicate changes in continental dynamics acting in North China over Cenozoic time.

关键词： fault kinematics tectonic stress regime Qinling and Tanlu fault zones

Structure and species composition of tree stands on verges and slopes along a major highway in Hong Kong

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Journal of Forestry Research 2023年第5期34卷 1347-1358页

作者： louis Shing Him Lee Hao zhang Kathy Tze Kwun Ng Shun Cheong Lo Alan Siu Lun Yu Faculty of Design and Environment Technological and HigherEducation Institute of Hong KongHong KongPeople’s Republic of China Landscape Division Highways DepartmentHong KongPeople’s Republic of China Greening Landscape and Tree Management SectionDevelopment BureauHong KongPeople’s Republic of China

Arboricultural research focusing on transport land use was lacking in Hong *** highway slopes were registered in the Systematic Identification of Maintenance Responsibility of Slopes in the Territory(SIMAR),abbreviated as SIMAR *** aimed to analyze patterns in the structure and species composition of the tree stock along a highway in Hong Kong and examined how a slope registration system could help explain the characteristics of urban *** 53 slopes and 52 verges along San Tin Highway,Hong Kong were randomly *** trees on each slope and verge were collectively sampled as a tree *** variables,namely tree abundance,species richness,maximum tree height,Shannon-Wiener diversity,Simpson's dominance,and Pielou's evenness were measured for each *** addition,a limited visual tree risk assessment was *** 7,209 trees in 23 species were *** richness was low,ranging from one to eight species per *** and non-SIMAR slopes were *** slopes had significantly higher species richness,diversity,evenness but lower dominance,with mean difference of 1.41 species,0.17,0.17 *** slopes were associated with lower tree risk *** training regression models,boosting as an ensemble method arbitrarily raised the explanatory power and the predictive accuracy of some *** height,length,angle and area could be significant predictors of the biodiversity-related *** research can sample more habitat characteristics related to the structure and species composition of slopes and verges which were important components of urban forestry.

关键词： Highway greenery Roadside tree management Tree risk assessment Monospecific urban forest Slope geophysical environment Urban forests