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Active shim coils design for Halbach magnet based on inverse boundary element method

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Magnetic Resonance Letters 2022年第3期2卷 159-169页

作者： Yajie Xu feng Wang Ya Wang peng yu Jingzhong Zhang Xiaodong yang Suzhou Institute of Biomedical Engineering and Technology Chinese Academy of SciencesSuzhou215163China School of Electronics and Information Engineering Changchun University of Science and TechnologyChangchun130022China School of Biomedical Engineering(Suzhou) Division of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefei230026China Jinan Guoke Medical Technology Development Co. LtdJinan250101China

With advantages of small volume,high field strength,and compact stray field,the Halbach array magnet is of great potential in desktop NMR ***,field inhomogeneity poses a main obstacle to its *** shimming is necessary for improving the field *** active shim coil design method for cylindrical Halbach magnet based on inverse boundary element method(iBEM)is introduced in this *** coils targeting 1st~3rd and Z4/Z5/Z6 spherical harmonic(SH)terms were designed with constraints of field accuracy,resistance,inductance,and current *** loops and symmetric property influence were discussed to further improve the performance of high-order shim ***,with the prototype of the shim coils constructed,field pattern and SH transformation proved that the coils designed could fit the target SH distribution,though contamination from low-order components existed in highorder terms.A practical shimming experiment on the Halbach magnet has improved the homogeneity from 40.3 ppm to 3.8 ppm in radius 2.5 mm,height 5 mm cylindrical sample space,verifying the coils'compensation *** work provides a flexible inverse coil design method for cylindrical Halbach magnet and discusses the high-order shim coil design and implementation,which is potential in nuclear magnetic resonance applications based on Halbach magnet arrays.

关键词： Active shimming iBEM Halbach Magnetic resonance

Thick-skinned Contractional Salt Structures in the Kuqa Depression,the Northern Tarim Basin:Constraints from Physical Experiments

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Acta Geologica Sinica(English Edition) 2008年第2期82卷 327-333页

作者： yu Yixin TANG Liangjie yang Wenjing JIN Wenzheng peng Gengxin lei Ganglin State Key Laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 Basin ＆ Reservoir Research Center China University of Petroleum Beijing 102249 Research Institute of Tarim Oilfield Korla Xinjiang 840000

Thick-skinned contractional salt structures are widely developed in the western Kuqa depression, northern Tarim basin. To understand the mechanisms that govern the development of these structures, physical experiments are conducted and the results show that they are largely governed by the activities of basement faults and the forming of paleo-uplifts and basement slopes. The model materials in this study are dry sand, vaseline and plasticene （or hard foam）, simulating the suprasalt, salt, and subsalt layers respectively. The experiments show that, due to the activities of basement faults and the forming of the paleo-uplifts, salt bodies usually accumulate and thicken significantly on the middle top of the paleo-uplifts which are constrained by the pre-exiting boundary faults. The development of large-scale thrust faults and salt nappes is favored by the basement slops with larger dips. The experiments also conclude that differential structural deformation could occur between the subsalt and suprasalt layers because of the presence of salt layers. Their geometries and the locations of structural highs are different, despite of the great similarities in the uplifted areas. The pierced salt diapir is not observed in the experiments, which indicates that the contractional shortening does not effectively accelerate the development of the salt diapir.

关键词： thick-skinned contraction basement structures salt structures physical modeling Kuqa depression

Radical organometallic nanocages with redox switchable poly-NHC ligands

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Nano Research 2023年第7期16卷 10678-10683页

作者： Guang-feng Jin Yan-Zhen Zhang Le yu Wei-Ling Jiang yang Li Li-Ying Sun peng Li Ying-feng Han Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education College of Chemistry and Materials ScienceNorthwest UniversityXi’an 710127China Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan UniversityShanghai 200438China

Developing discrete radical organometallic nanocages is essential for fabricating functional *** this study,we construct a series of poly-NHC-based(NHC=N-heterocyclic carbene)organometallic nanocages 3a-3c with different sizes by employing redox-active bis(triarylamine)derivatives with differentπ-conjugated spacers as building *** varied sizes of nanocages 3a-3c modulate the distance of the redox-active centers and reversibly convert them to radical nanocages 3a^(2+)-3c^(2+)through chemical and electrochemical *** nanocages 3a^(2+)-3c^(2+)display clear bond and angle alteration and retention of their three-dimensional *** work not only merely proves that these nanocages are excellent stimulus-responsive materials but also opens a door to the rational design of novel radical organometallic nanocages.

关键词： stimuli-responsive organometallic nanocage N-heterocyclic carbene radical

Irradiation Resistance of CoCrCuFeNi High Entropy Alloy under Successive Bombardment

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Acta Metallurgica Sinica(English Letters) 2023年第9期36卷 1482-1492页

作者： Rui Li lei Guo yu Liu Qingsong Xu Qing peng School of Mechanical Engineering University of Science and Technology BeijingBeijing100083China Physics Department King Fahd University of Petroleum and Minerals31261DhahranSaudi Arabia K.A.CARE Energy Research and Innovation Center at Dhahran 31261DhahranSaudi Arabia Interdisciplinary Research Center for Hydrogen and Energy Storage King Fahd University of Petroleum and Minerals31261DhahranSaudi Arabia

With the excellent irradiation resistance due to the chemical complexity,high entropy alloys have attracted considerable attention in the design of nuclear structural ***,their performance under successive bombardments remains *** this study,we have investigated the irradiation resistance of equiatomic CoCrCuFeNi HEA compared with Ni metal using molecular dynamics *** evolution of defects such as point defects,defect clusters and dislocations after 400 times of bombardments is *** results show that CoCrCuFeNi has fewer point defects than Ni ***,CoCrCuFeNi has smaller interstitial clusters size,lower interstitial-type Frank partial dislocation density,shorter average interstitial-type Frank partial dislocation length and higher average vacancy formation *** findings suggest that CoCrCuFeNi has superior radiation resistance under successive bombardments due to its high entropy effect.

关键词： High entropy alloys Irradiation resistance Defects Dislocations

Infrared Photodetectors and Image Arrays Made with Organic Semiconductors

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Chinese Journal of Polymer Science 2023年第10期41卷 1629-1637页

作者： Zhi-Ming Zhong feng peng lei Ying Zhen-Qiang Huang Wen-Kai Zhong Gang yu Yong Cao Fei Huang Institute of Polymer Optoelectronic Materials and Devices State Key Laboratory of Luminescent Materials and DevicesSouth China University of TechnologyGuangzhou510640China

Combining the strategies of introducing larger heteroatom,regio-regular backbone and extended branching position of side-chain,we developed polymer semiconductors(PPCPD)with narrow band-gap to construct the photosensing layer of thin-film photodiodes and image *** spectral response of the resulting organic photodiodes spans from the near ultra-violet to short-wavelength infrared *** performance of these short-wavelength infrared photodiodes in 900–1200 nm range achieved a level competitive with that of indium gallium arsenide-based inorganic crystalline detectors,exhibiting a specific detectivity of 5.55×1012 Jones at 1.15µ*** photodetectivity and quantum efficiency in photodiode with amorphous/nanocrystalline thin-films of 100–200 nm thickness enabled high pixel-density image arrays without pixel-level-patterning in the sensing layer.1×256 linear diode arrays with 25µm×25µm pixel pitch were achieved,enabling high pixel-density short-wavelength infrared imaging at room temperature.

关键词： Conjugated polymer Organic semiconductor Infrared Photodetector Image array

Effect of cooling time t8/5 on microstructure and toughness of Nb-Ti- Mo microalloyed C-Mn steel

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Journal of Iron and Steel Research International 2018年第10期25卷 1078-1085页

作者： Xiao-nan Wang Xia-ming Chen feng Wen peng-fei Guo lei yang Qian Yan Hong-shuang Di Shagang School of Iron and Steel Soochow University Suzhou 215021 Jiangsu China State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 Liaoning China

In order to further optimize welding process of Nb-Ti-Mo microalloyed steel, welding thermal cycles on coarse-grained heat-affected zone （CGHAZ） of welded joints were simulated using Gleeble 1500. The microstructure and low-temperature impact fracture were investigated using a scanning electron microscope and a pendulum impact machine, respectively. Moreover, the relationship between cooling time ts/5 and the microstructure of CGHAZ was discussed, and the effect of microstructure on impact toughness was also studied. As cooling time increased, martensite fraction decreased from 97.8% （3 s） to 3.0% （60 s）. The fraction of martensite/austenite （M/A） constituent increased from 2.2% （3 s） to 39.0% （60 s）, its shape changed from granular to strip, and the maximum length increased from 2.4 μm （3 s） to 7.0 μm （60 s）. As cooling time increased, the prior austenite grain size increased from 34.0 μm （3 s） to 49.0 gm （60 s）, the impact absorption energy reduced from 101.8 J （5 s） to 7.2 J （60 s）, and the fracture mechanism changed from quasi-cleavage fracture to cleavage fracture. The decreased toughness of CGHAZ was due to the reduction of lath martensite-content, coarsening of original austenite grain, and increase and coarsening of M/A constituent. The heat input was controlled under 7 kJ cm-1 during actual welding for these steels.

关键词： Microalloyed C-Mn steel Cooling time - Impact absorption energy M/A constituent Coarse-grained heataffected zone Heat input

Distributed Energy Saving Mechanism Based on CoMP in LTE-A System

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China Communications 2016年第7期13卷 39-47页

作者： Fei Zheng Wenjing Li Luoming Meng peng yu lei peng State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Electronics and Information Engineering Faculty Jinggangshan University

To reduce the energy consumption of the LTE-A system,a distributed energy-saving mechanism based on Co MP(Co MPDESM) is proposed to solve the inadequate coverage problem under the dormant ***,the network is divided into clusters based on the equivalent cell ***,we transfer global optimization into a group of ***,a joint processing-based cooperative cell selection model is constructed to determine cooperative cells and dormant ***,the compensative cells with a determined threshold are selected to control users' ***,a simulation is implemented in *** show that the energy-saving rate can reach 36.4% and that the mechanism meets the network coverage ***,joint processing can be effectively applied in an energy saving mechanism and used to improve the network performance of edge users without increasing transmission power.

关键词： LTE-A distributed energy-saving mechanism CoMP equivalent cell principle energy-saving rate

Selenium distribution and nitrate metabolism in hydroponic lettuce(Lactuca sativa L.): Effects of selenium forms and light spectra

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Journal of Integrative Agriculture 2020年第1期19卷 133-144页

作者： BIAN Zhong-hua lei Bo CHENG Rui-feng WANG yu LI Tao yang Qi-chang Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agricultural SciencesBeijing 100081P.R.China School of Animal Rural and Environmental SciencesNottingham Trent UniversityBrackenhurst CampusNG250QFUK

A deficiency in selenium(Se) in the human diet is a worldwide problem. The intake of Se-rich vegetables can be a safe way to combat Se deficiency for humans. However, most leafy vegetables can accumulate a high content of nitrates, which poses a potential threat to human health. Light is an important environmental factor that regulates the uptake and distribution of mineral elements and nitrogen metabolism in plants. However, the effects of Se forms and light conditions, especially light spectra, on the uptake and translocation of Se and on nitrate reduction are poorly understood. In this study, lettuce(Lactuca sativa L.) was treated with exogenous Se applied as selenate(10 mmol L^-1) and selenite(0.5 mmol L^-1) and grown under five different light spectra: fluorescent light(FL), monochromatic red LED light(R), monochromatic blue LED light(B), and mixed red and blue LED light with a red to blue light ratio at 4(R/B=4), 8(R/B=8), and 12(R/B=12), respectively. The effects of light spectra and Se forms on plant growth, photosynthetic performance, Se accumulation and nitrate reduction were investigated. The results showed that the light spectra and Se forms had significant interactions for plant growth, foliar Se accumulation and nitrate reduction. The Se concentration and nitrate content in the leaves were negatively correlated with the percentage of red light from the light sources. Compared to Se applied as selenite, exogenous Se applied as selenate was more effective in reducing nitrate via promoting nitrate reductase and glutamate synthase activities. The lowest nitrate content and highest plant biomass were observed under R/B=8 for both the selenate and selenite treatments. The significant effect of the light spectra on the root concentration factor and translocation factor of Se resulted in marked variations in the Se concentrations in the roots and leaves. Compared with FL, red and blue LED light led to significant decreases in the foliar Se concentration. The r

关键词： selenium light spectra nitrates nitrogen metabolism enzymes LEDs Lactuca sativa L.

Giving maize an excited start-Effects of dopamine on maize germination

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Journal of Integrative Agriculture 2020年第11期19卷 2690-2698页

作者： CHENG Hang-yuan WANG Xing feng Tian-yu peng Chuan-xi WANG Wei yang Mu-yu ZHOU yu-yi College of Agronomy and Biotechnology China Agricultural UniversityBeijing 100193P.R.China Engineering Research Center of Plant Growth Regulator Ministry of EducationBeijing 100193P.R.China

Dopamine(DA)is a neurotransmitter which takes charge of brain activities about memory and self-stimulation behavior in ***,our results suggest that DA could also give maize an“excited state”.The results showed that 1 mmol L–1 DA promoted maize germination by 23.2%significantly,and accelerated the growth rate of roots and shoots by 21.4 and 24.7%,*** we all known,abscisic acid(ABA)is the key hormone involved in seed *** our research,ABA levels in roots and shoots dramatically decreased by 16.45 and 57.57%,*** further investigate how DA reduces the ABA level in budding seed,we studied ABA synthesis and catabolism *** expression of key ABA-synthesis genes,such as ZmNCED1,ZmNCED3 and ZmZEP were down-regulated by ***,the expression levels of ABA8OX1a and ABA8OX1b which are major transcripts of ABA 8´-hydroxylase in ABA catabolism were up-regulated at least 1.5-and 4.6-fold,*** results enriched the functions of animal hormones in plants.

关键词： dopamine(DA) maize germination ABA synthesis ABA catabolism