检索结果-南通市图书馆

Neural Regeneration Research 2022年第6期17卷 1343-1347页

作者： Wei Pi ci Li Meng zhang Wei zhang Pei-Xun zhang Department of Orthopedics and Trauma Peking University People’s HospitalPeking UniversityBeijingChina Key Laboratory of Trauma and Neural Regeneration Peking UniversityBeijingChina National Center for Trauma Medicine BeijingChina

Studies have shown that myelin-associated glycoprotein(MAG)can inhibit axon regeneration after nerve ***,the effects of MAG on neuroma formation after peripheral nerve injury remain poorly *** this study,local injection of MAG combined with nerve cap made of chitin conduit was used to intervene with the formation of painful neuroma after sciatic nerve transfection in *** 8 weeks of combined treatment,the autotomy behaviors were reduced in rats subjected to sciatic nerve transfection,the mRNA expression of nerve growth factor,a pain marker,in the proximal nerve stump was decreased,the density of regenerated axons was decreased,the thickness of the myelin sheath was increased,and the ratio of unmyelinated to myelinated axons was ***,the percentage of collagen fiber area and the percentage of fibrosis marker alpha-smooth muscle actin positive staining area in the proximal nerve stump were *** combined treatment exhibited superior effects in these measures to chitin conduit treatment *** findings suggest that MAG combined with chitin conduit synergistically inhibits the formation of painful neuroma after sciatic nerve transection and alleviates neuropathic *** study was approved by the Animal Ethics Committee of Peking University People’s Hospital(approval No.2019PHE027)on December 5,2019.

关键词： autotomy axon chitin conduit fibrosis myelin-associated glycoprotein painful neuroma peripheral nerve regeneration

Frequency Domain Fatigue Evaluation on SCR Girth-Weld Based on Structural Stress

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第2期38卷 255-270页

作者： zhang Long ZHAO tian-feng College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

The Steel Catenary Riser(SCR)is a vital component for transporting oil and gas from the seabed to the floating *** harsh environmental conditions and complex platform motion make the SCR’s girth-weld prone to fatigue *** structural stress fatigue theory and Master S-N curve method provide accurate predictions for the fatigue damage on the welded joints,which demonstrate significant potential and compatibility in multi-axial and random fatigue ***,we propose a new frequency fatigue model subjected to welded joints of SCR under multiaxial stress,which fully integrates the mesh-insensitive structural stress and frequency domain random process and transforms the conventional welding fatigue technique of SCR into a spectrum analysis technique utilizing structural ***,a full-scale FE model of SCR with welds is established to obtain the modal structural stress of the girth weld and the frequency response function(FRF)of modal coordinate,and a biaxial fatigue evaluation about the girth weld of the SCR can be achieved by taking the effects of multi-load correlation and pipe-soil interaction into *** research results indicate that the frequency-domain fatigue results are aligned with the time-domain results,meeting the fatigue evaluation requirements of the SCR.

关键词： SCR girth weld random vibration self(cross)power spectrum structural stress method biaxial fatigue damage

Bimetallic water oxidation: One-site catalysis with two-sites oxidation

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2021年第12期30卷 1-7,I0001页

作者： Fei Xie Ming-tian zhang Center of Basic Molecular Science(CBMS) Department of ChemistryTsinghua UniversityBeijing 100084China

Water oxidation is the key half reaction to achieve full splitting of water to hydrogen and ***,a binuclear complex,[(L^(4-))Co_(2)~Ⅲ(OH)]ClO_(4),was reported as a stable and efficient homogenous catalyst for electrocatalytic water oxidation in 0.1 M phosphate buffer(pH 7.0).Cyclic voltammetry experiments indicated that the catalytic process proceed via "one-site catalysis with two-sites oxidation" mechanism in which both two metal sites store the required oxidation equivalents for water oxidation and O-O bond formation occurs by single-site water nucleophilic attack(WNA).

关键词： Water oxidation Bimetallic catalysis O-O bond formation Cobalt catalyst Oxygen evolution

An electroencephalography-based human-machine interface combined with contralateral C7 transfer in the treatment of brachial plexus injury

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2022年第12期17卷 2600-2605页

作者： Meng zhang ci Li Song-Yang Liu Feng-Shi zhang Pei-Xun zhang Department of Orthopedics and Trauma Peking University People’s HospitalBeijingChina Key Laboratory of Trauma and Neural Regeneration Peking UniversityBeijingChina National Center for Trauma Medicine BeijingChina

Transferring the contralateral C7 nerve root to the median or radial nerve has become an important means of repairing brachial plexus nerve ***,outcomes have been ***(EEG)-based human-machine interfaces have achieved promising results in promoting neurological recovery by controlling a distal exoskeleton to perform functional limb exercises early after nerve injury,which maintains target muscle activity and promotes the neurological rehabilitation *** review summarizes the progress of research in EEG-based human-machine interface combined with contralateral C7 transfer repair of brachial plexus nerve *** transfer may result in loss of nerve function in the donor area,so only nerves with minimal impact on the donor area,such as the C7 nerve,should be selected as the *** tendon transfer does not fully restore optimal joint function,so multiple functions often need to be reestablished *** with traditional manual rehabilitation,EEG-based human-machine interfaces have the potential to maximize patient initiative and promote nerve regeneration and cortical remodeling,which facilitates neurological *** the early stages of brachial plexus injury treatment,the use of an EEG-based human-machine interface combined with contralateral C7 transfer can facilitate postoperative neurological recovery by making full use of the brain’s computational capabilities and actively controlling functional exercise with the aid of external *** can also prevent disuse atrophy of muscles and target organs and maintain neuromuscular junction *** cortical remodeling is also particularly important for neurological recovery after contralateral C7 *** studies are needed to investigate the mechanism by which early movement delays neuromuscular junction damage and promotes cortical *** this mechanism should help guide the development of neurolog

关键词： arm injuries brachial plexus brain-computer interfaces nerve transfer nerve regeneration nerve tissue neurofeedback neurological rehabilitation user-computer interface

Unmanned Aerial Vehicle Formation Inspired by Bird Flocking and Foraging Behavior

在线全文

学校读者我要写书评

暂无评论

International Journal of Automation and computing 2018年第4期15卷 402-416页

作者： tian-Jie zhang Beijing University of Aeronautics and Astronautics Beijing 100191China

This paper considers a multiple unmanned aerial vehicles （UAV） formation problem and proposes a new method inspired by bird flocking and foraging behavior. A bidirectional communication network, a navigator based on bird foraging behavior, a controller based on bird interaction and a movement switch are developed for multi-UAV formation. Lyapunov＇s second method and mechanical energy method are adopted for stability analysis. Parameters of the controller are optimized by Levy-flight based pigeon inspired optimization （Levy-PIO）. Patrol missions along a square and an S shaped trajectory are designed to test this formation method. Simula- tions prove that the bird flocking and foraging strategy can accomplish the mission and obtain satisfying performance.

关键词： Unmanned aerial vehicle(UAV) formation bird flocking foraging pigeon-inspired optimization Levy-flight.

Formation Characteristics of Calcium Ferrite in Low Silicon Sinter

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2011年第10期18卷 1-7页

作者： WANG Yi-ci zhang Jian-liang zhang Fang LUO Guo-ping College of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China College of Material and Metallurgy University of Science and Technology Inner Mongolia Baotou 014010 Inner Mongolia China

Influence of sintering temperature, basicity and MgO content on the formation characteristics of calcium ferrite in low silicon sinter of Baotou Iron and Steel Company was studied by means of mini-sintering test and mineralographic microscope analysis. In addition, the suitable sintering parameters such as temperature and basicity were explored. The results found that optimum temperature for the formation of calcium ferrite is 1 280℃, the basicity of 2.5-2.8 is helpful to the development of acicular or columnar calcium ferrite, and MgO content in the low silicon sintering raw materials should be lower than 2.8 % because MgO can intensively inhibit the formation of calcium ferrite. And calcium ferrite in the sinter belongs to calcium ferrite with low calcium, which is different from that in ordinary sinter at home and abroad. So, it provided theoretical basis for promoting formation of calcium ferrite in low silicon sinter and improving properties of sinter.

关键词： low silicon sinter formation characteristics calcium ferrite sintering temperature basicity

Enhanced photoluminescence of monolayer MoS_(2)on stepped gold structure

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第8期31卷 639-644页

作者： Yu-Chun Liu Xin Tan tian-ci Shen Fu-Xing Gu School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai 200093China

Different Mo S_(2)/Au heterostructures can play an important role in tuning the photoluminescence(PL)and optoelectrical properties of monolayer Mo S_(2).Previous studies of PL of Mo S_(2)/Au heterostructures were mainly limited to the PL enhancement by using different Au nanostructures and PL quenching of monolayer Mo S_(2)on flat Au ***,we demonstrate the enhanced excitonic PL emissions of monolayer Mo S_(2)/Au heterostructures on Si/Si O_(2)*** transferring the continuous monolayer Mo S_(2)onto a stepped Au structure consisting of 60-nm and 100-nm Au films,the Mo S_(2)/Au-60 and Mo S_(2)/Au-100 heterostructures exhibit enhanced PL emissions,each with a blue-shifted PL peak in comparison with the Mo S_(2)/Si O_(2).Furthermore,the PL intensity of Mo S_(2)/Au-60 is about twice larger than that of Mo S_(2)/*** different enhanced excitonic PL emissions in Mo S_(2)/Au heterostructures can be attributed to the different charge transfer effects modified by the stepped Au *** work may provide an insight into the excitonic PL and charge transfer effect of Mo S_(2)on Au film and yield novel phenomena in Mo S_(2)/Au heterostructures for further study of PL tuning and optoelectrical properties.

关键词： MoS_(2) stepped gold heterostructures enhanced photoluminescence

A novel subsidence monitoring technique based on space-surface bistatic differential interferometry using GNSS as transmitters

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2015年第6期58卷 68-83页

作者： ZENG Tao zhang tian tian WeiMing HU Cheng Beijing Key Laboratory of Embedded Real-time Information Processing Technology Radar Research Laboratory School of Information and ElectronicsBeijing Institute of Technology

Synthetic Aperture Radar Differential Interferometry(DIn SAR) technique is an effective tool with large coverage and high spatial accuracy for subsidence monitoring. Nevertheless, the temporal resolution is usually poor so that rapid deformation cannot be measured due to the long revisit time of radar *** SAR Differential Interferometry technique using Global Navigation Satellite System(GNSS) as illuminator has a shorter revisit time, whereas the measurement accuracy is constrained by low signal power, narrow bandwidth and atmospheric delay error. To cope with these problems, in this paper, we propose a novel subsidence monitoring technique based on Space-Surface bistatic Differential Interferometry(SS-DI) with GNSS transmitters, where two stations consist of a reference one and a measurement one that are deployed on the ground. First, we applied a space differential processing between two stations to cancel identical errors such as tropospheric and ionospheric errors etc. Then we used a long time coherent integration to improve the signal noise ratio. Subsequently, we also utilized a time differential processing to construct double differential equations with respect to unknown deformation variables. Finally, we solved the equations to obtain a highly accurate estimation of three dimension deformation. Furthermore, an SS-DI experiment using Beidou-2 as transmitters was carried out to validate the proposed method, where a high accuracy(0.01 mm) device was utilized to simulate subsidence deformation. The experimental results reveal that the proposed method has better performance of spatial measurement accuracy of 0.53 mm compared with differential GPS method.

关键词： differential interferometry subsidence monitoring Beidou-2/Compass-2 space-surface bistatic radar differential GPS

Control Policy Learning Design for Vehicle Urban Positioning via BeiDou Navigation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第1期37卷 114-135页

作者： QIN Yahang zhang Chengye CHEN ci XIE Shengli LEWIS Frank L School of Automation Guangdong University of TechnologyGuangzhou 510006China Guangdong Key Laboratory of IoT Information Technology Guangzhou 510006China. Center for Intelligent Batch Manufacturing Based on IoT Technology Key Laboratory of Intelligent Detection and The Internet of Things in Manufacturing Ministry of EducationGuangzhou 510006China Guangdong-HongKong-Macao Joint Laboratory for Smart Discrete Manufacturing Guangzhou 510006China Key Laboratory of Intelligent Information Processing and System Integration of IoT Ministry of EducationGuangzhou 510006China. UTA Research Institute The University of Texas at ArlingtonFort WorthTX 76019USA

This paper presents a learning-based control policy design for point-to-point vehicle positioning in the urban environment via BeiDou *** navigating in urban canyons,the multipath effect is a kind of interference that causes the navigation signal to drift and thus imposes severe impacts on vehicle localization due to the reflection and diffraction of the BeiDou ***,the authors formulated the navigation control system with unknown vehicle dynamics into an optimal control-seeking problem through a linear discrete-time system,and the point-to-point localization control is modeled and handled by leveraging off-policy reinforcement learning for feedback *** proposed learning-based design guarantees optimality with prescribed performance and also stabilizes the closed-loop navigation system,without the full knowledge of the vehicle *** is seen that the proposed method can withstand the impact of the multipath effect while satisfying the prescribed convergence rate.A case study demonstrates that the proposed algorithms effectively drive the vehicle to a desired setpoint under the multipath effect introduced by actual experiments of BeiDou navigation in the urban environment.

关键词： BeiDou navigation multipath effect prescribed convergence rate reinforcement learning urban localization.

Relative volume comparison of Ricci flow

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2021年第9期64卷 1937-1950页

作者： Gang tian Zhenlei zhang School of Mathematical Sciences and Beijing International Center for Mathematical Research Peking UniversityBeijing 100871China School of Mathematical Sciences Capital Normal UniversityBeijing 100048China

In this paper we derive a relative volume comparison of Ricci flow under a certain local curvature *** is a refinement of Perelman’s no local collapsing theorem in Perelman(2002).

关键词： Ricci flow relative volume comparison local entropy

同方期刊数据库