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适用于中点钳位H桥五电平逆变器的快速SVPWM算法

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电机与控制学报 2022年第11期26卷 31-38页

作者：吴宇涛贾何飞邓焰浙江大学电气工程学院浙江杭州310027

针对传统多电平空间矢量脉宽调制技术(SVPWM)计算量大的问题,提出一种适用于中点钳位(NPC)H桥五电平逆变器的快速SVPWM算法。首先分析了传统五电平SVPWM算法复杂度高的本质原因。在分析五电平空间矢量图的基础上,提出了一种新型扇区分... 详细信息

针对传统多电平空间矢量脉宽调制技术(SVPWM)计算量大的问题,提出一种适用于中点钳位(NPC)H桥五电平逆变器的快速SVPWM算法。首先分析了传统五电平SVPWM算法复杂度高的本质原因。在分析五电平空间矢量图的基础上,提出了一种新型扇区分割方案,将五电平空间矢量图等效为4个两电平空间矢量图的组合。相较于传统五电平SVPWM算法,新算法应用两电平SVPWM的方法完成运算,从而大幅降低了在参考矢量位置判断和基本矢量作用时间计算部分的计算量。最后搭建了三相NPC/H桥型五电平逆变器原理样机,实验结果表明,新算法的程序运行时间仅为传统算法的55.27%,且输出电压效果保持了与传统算法相同的优越性。

关键词：中点钳位H桥五电平逆变器空间矢量调制空间矢量图扇区分割程序耗时快速算法

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miRNA-21-5p is an important contributor to the promotion of injured peripheral nerve regeneration using hypoxia-pretreated bone marrow-derived neural crest cells

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Neural Regeneration Research 2025年第1期20卷 277-290页

作者： Meng Cong Jing-Jing Hu Yan Yu Xiao-Li Li Xiao-Ting Sun Li-Ting Wang Xia Wu Ling-Jie Zhu Xiao-jia Yang Qian-Ru he fei Ding Hai-Yan Shi School of Medicine Nantong UniversityNantongJiangsu ProvinceChina Key Laboratory of Neuroregeneration of jiangsu and Ministry of Education and Coinnovation Center of Neuroregeneration Nantong UniversityNantongJiangsu ProvinceChina Department of Physiology Jiangsu Health Vocational CollegeNanjingJiangsu ProvinceChina Department of Pathology Affiliated Hospital of Nantong UniversityNantongJiangsu ProvinceChina jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair Affiliated Hospital of Nantong UniversityNantongJiangsu ProvinceChina

Our previous study found that rat bone marrow–derived neural crest cells(acting as Schwann cell progenitors)have the potential to promote long-distance nerve ***-based therapy can enhance peripheral nerve repair and regeneration through paracrine bioactive factors and intercellular ***,the complex contributions of various types of soluble cytokines and extracellular vesicle cargos to the secretome remain *** investigate the role of the secretome and extracellular vesicles in repairing damaged peripheral nerves,we collected conditioned culture medium from hypoxia-pretreated neural crest cells,and found that it significantly promoted the repair of sensory neurons damaged by oxygen-glucose *** mRNA expression of trophic factors was highly expressed in hypoxia-pretreated neural crest *** performed RNA sequencing and bioinformatics analysis and found that miR-21-5p was enriched in hypoxia-pretreated extracellular vesicles of neural crest ***,to further clarify the role of hypoxia-pretreated neural crest cell extracellular vesicles rich in miR-21-5p in axonal growth and regeneration of sensory neurons,we used a microfluidic axonal dissociation model of sensory neurons in vitro,and found that hypoxia-pretreated neural crest cell extracellular vesicles promoted axonal growth and regeneration of sensory neurons,which was greatly dependent on loaded ***,we constructed a miR-21-5p-loaded neural conduit to repair the sciatic nerve defect in rats and found that the motor and sensory functions of injured rat hind limb,as well as muscle tissue morphology of the hind limbs,were obviously *** findings suggest that hypoxia-pretreated neural crest extracellular vesicles are natural nanoparticles rich in ***-21-5p is one of the main contributors to promoting nerve regeneration by the neural crest cell *** helps to explain the mechanism of action of the secretome and e

关键词： axotomy cell-free therapy conditioned medium extracellular vesicles hypoxic preconditioning microRNA oxygen-glucose deprivation peripheral nerve injury Schwann cell precursors

Prediction and stratification for the surgical adverse events after minimally invasive esophagectomy:A two-center retrospective study

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World Journal of Gastroenterology 2025年第3期31卷 50-61页

作者： Qi-Hong Zhong jiang-Shan Huang fei-Long Guo Jing-Yu Wu Mao-Xiu Yuan jia-Fu Zhu Wen-Wei Lin Sui Chen Zhen-Yang Zhang jiang-Bo Lin Department of Thoracic Surgery Fujian Medical University Union HospitalFuzhou 350001Fujian ProvinceChina The Graduate School Fujian Medical UniversityFuzhou 350001Fujian ProvinceChina Department of Thoracic Surgery Affiliated Hospital of Jinggangshan UniversityJi’an 343000Jiangxi ProvinceChina

BACKGROUND Minimally invasive esophagectomy(MIE)is a widely accepted treatment for esophageal cancer,yet it is associated with a significant risk of surgical adverse events(SAEs),which can compromise patient recovery and long-term *** preoperative identification of high-risk patients is critical for improving *** To establish and validate a risk prediction and stratification model for the risk of SAEs in patients with *** This retrospective study included 747 patients who underwent MIE at two centers from January 2019 to February *** were separated into a train set(n=549)and a validation set(n=198).After screening by least absolute shrinkage and selection operator regression,multivariate logistic regression analyzed clinical and intraoperative variables to identify independent risk factors for SAEs.A risk stratification model was constructed and validated to predict the probability of *** SAEs occurred in 10.2%of patients in train set and 13.6%in the validation *** with SAE had significantly higher complication rate and a longer hospital stay after *** key independent risk factors identified included chronic obstructive pulmonary disease,a history of alcohol consumption,low forced expiratory volume in the first second,and low albumin *** stratification model has excellent prediction accuracy,with an area under the curve of 0.889 for the training set and an area under the curve of 0.793 for the validation *** The developed risk stratification model effectively predicts the risk of SAEs in patients undergoing MIE,facilitating targeted preoperative interventions and improving perioperative management.

关键词： Surgical adverse events Minimally invasive esophagectomy Esophageal cancer Stratification model Perioperative management

Synthesis of polyaluminum chloride with a membrane reactor:Process characteristics and membrane fouling

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Journal of Environmental Sciences 2011年第11期23卷 1794-1798页

作者： Zhiqian jia fei he Zhongzhou Liu College of Chemistry Beijing Normal University Beijing 100875 China Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

Polyaluminum chloride was synthesized with a membrane reactor,in which NaOH was added into AlCl 3 solution through the membrane’s micropores to reduce the NaOH droplets *** content of the most efficient species increased to about 80%.The process characteristics in the reaction （i.e.,flow velocity,pressure drop）,and membrane fouling and cleaning were *** evolution of both flow velocity and pressure drop during the reaction were related to changes in species distribution and solution *** process characteristics were well interpreted in terms of the Bernoulli *** reaction,the membranes were recovered by cleaning with diluted hydrochloride *** study is crucial for process design and scale-up of membrane reactors.

关键词： polyaluminum chloride membrane reactor flocculant Alb Al13

New strategies for asymmetric photocatalysis: asymmetric organocatalytic/photoredox relay catalysis for efficient synthesis of polycyclic compounds containing vicinal amino alcohols

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Science China Chemistry 2024年第3期67卷 945-952页

作者： jia-Lu Zhang Wen-Bo he Xiu-Qin Hu Peng-fei Xu State Key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical EngineeringLanzhou UniversityLanzhou 730000China State Key Laboratory of Veterinary Etiological Biology College of Veterinary MedicineLanzhou UniversityLanzhou Veterinary Research InstituteChinese Academy of Agricultural SciencesLanzhou 730000China MOE Frontiers Science Center for Rare Isotopes Lanzhou UniversityLanzhou 730000China

An asymmetric catalytic strategy in photocatalysis utilizing a chirality-induced approach through an organocatalytic/photoredox relay catalysis strategy is successfully achieved for the rapid construction of polycyclic compounds containing vicinal amino alcohols in a one-pot protocol. This methodology facilitates the efficient synthesis of diverse substituted polycyclic tetrahydroquinoline and benzofuran-derived vicinal amino alcohols, each containing five consecutive chiral centers, with high yields,excellent diastereoselectivities and enantioselectivities(up to 95% yield, >20:1 dr and 98% ee), under mild reaction conditions driven by sequential bifunctional squaramide organocatalyst-catalyzed [4+2] annulation and photocatalyst-catalyzed ketyl radical addition cyclization reaction process. Furthermore, investigations into the stereoselectivity mechanism and high-resolution mass spectrometry(HRMS) experiments on free radical trapping have provided evidence for elucidating the detailed mechanism of chirality-induced processes and chiral intermediate conversions in this procedure.

关键词： enantioselective photocatalysis asymmetric organocatalytic/photocatalysis relay catalysis five consecutive chiral centers chirality-induced strategy chirality vicinal amino alcohols

Numerical estimation of thermal insulation performance of different coverage schemes at three places for snow storage

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Advances in Climate Change Research 2021年第6期12卷 903-912页

作者： WANG Xing QIN Da-he REN jia-Wen WANG fei-Teng State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou730000China University of Chinese Academy of Sciences Beijing100049China

With increasing global warming, the skiing season is shortened to different degrees all over the world. As a crucial way to ensure the sustainable development of the ski industry, snow storage has been gradually studied and applied in Europe. Covering thermal insulation materials is a key engineering measure for the success of snow storage. This study used numerical methods rather than an experimental method to evaluate the thermal insulation performance of nine snow storage coverage schemes in Harbin, Beijing, and Altay, China. We investigated the thermal insulation performance of nine snow storage coverage schemes (three natural materials and six artificial ones) using a solar radiation method and an implicit finite difference method. Sensitivity analyses were conducted, and the cost performance of schemes 5–9 were analyzed. Based on the cost and thermal insulation performance, we used schemes 4 (geotextile, straw bale), 5 (geotextile, extruded polystyrene foam), and 7 (geotextile, polyurethane foam) to evaluate the snow storage effects in Harbin, Beijing, and Altay. Results showed that among schemes 1–9, scheme 7 has the best thermal insulation performance. If natural materials are used, then scheme 3 gives the best thermal insulation performance. Among schemes 5–9, scheme 5 is the most economical. The heat transfer in Beijing is higher than that in Harbin and Altay, while the latter two show similar heat transfers. The combination of meteorological conditions and coverage schemes influence the melting rate of snowpacks. The melting rate of snowpacks can be reduced with an optimized coverage scheme. The proposed methods can serve the selection of coverage schemes for snow storage.

关键词： Snow storage Coverage schemes Thermal insulation performance Numerical simulation

Redshift drift constraints on f（T） gravity

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Frontiers of physics 2015年第5期10卷 1-6页

作者： jia-jia Geng Rui-Yun Guo Dong-Ze he Jing-fei Zhang Xin Zhang Department of Physics College of Sciences Northeastern University Shenyang 110004 China Center for High Energy Physics Peking University Beijing 100080 China

We explore the impact of the Sandage-Loeb （SL） test on the precision of cosmological constraints for f（T） gravity theories. The SL test is an important supplement to current cosmological observations because it measures the redshift drift in the Lyman-α forest in the spectra of distant quasars, covering the ＂redshift desert＂ of 2 ≤ z ≤ 5. To avoid data inconsistency, we use the best-fit models based on current combined observational data as fiducial models to simulate 30 mock SL test data. We quantify the impact of these SL test data on parameter estimation for f（T） gravity theories. Two typical f（T） models are considered, the power-law model f（T）pL and the exponential-form model f（T）Exp. The results show that the SL test can effectively break the existing strong degeneracy between the present-day matter density Ωm and the Hubble constant Ho in other cosmological observations. For the considered f（T） models, a 30-year observation of the SL test can improve the constraint precision of Ωm and H0 enormously but cannot effectively improve the constraint precision of the model parameters.

关键词： redshift drift cosmological constraints dark energy modified gravity f(T) gravity

Diversifying Top-κRoutes with Spatial Constraints

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Journal of Computer Science & Technology 2019年第4期34卷 818-838页

作者： Hong-fei Xu Yu Gu jian-Zhong Qi jia-Yuan he Ge Yu College of Computer Science and Engineering Northeastern UniversityShenyang 110169China Department of Computing and Information Systems The University of MelbourneMelbourneVIC 3010Australia

Trip recommendation has become increasingly popular with the rapid growth of check-in data in location-based social *** existing studies focused only on the popularity of *** this paper,we consider further the usability of trip recommendation results through spatial *** thereby formulate a new type of queries named spatial diversified top-κroutes(SDκR)*** type of queries finds k trip routes with the highest popularity,each of which starts at a given starting point,consumes travel time within a given time budget,and passes through points of interest(POIs)of given *** two trip routes returned are diversified to a certain degree defined by the spatial distance between the two *** show that the SDkR problem is *** propose two precise algorithms to solve the *** first algorithm starts with identifying all candidate routes that satisfy the query constraints,and then searches for theκ-route combination with the highest *** second algorithm identifies the candidate routes and builds up the optimalκ-route combination progressively at the same ***,we propose an approximate algorithm to obtain even higher query efficiency with precision *** demonstrate the effectiveness and efficiency of the proposed algorithms on real *** experimental results show that our algorithms find popular routes with diversified POI *** approximate algorithm saves up to 90%of query time compared with the baseline algorithms.

关键词： trip recommendation spatial diversity route search check-in data

Harvesting random embedding for high-frequency change-point detection in temporal complex systems

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National Science Review 2022年第4期9卷 92-104页

作者： jia-Wen Hou Huan-fei Ma Dake he Jie Sun Qing Nie Wei Lin Research Institute of Intelligent Complex Systems Fudan University Centre for Computational Systems Biology Institute of Science and Technology for Brain-Inspired IntelligenceFudan University School of Mathematical Sciences Soochow University Xinhua Hospital Affiliated to Shanghai jiao Tong University School of Medicine School of Mathematical Sciences and Shanghai Center for Mathematical Sciences Fudan University Department of Mathematics Department of Developmental and Cell Biologyand NSF-Simons Center for Multiscale Cell Fate ResearchUniversity of California Shanghai Key Laboratory for Contemporary Applied Mathematics LNMS (Fudan University)and LCNBI (Fudan University) State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain ScienceInstitutes of Brain ScienceFudan University

Recent investigations have revealed that dynamics of complex networks and systems are crucially dependent on the temporal structures. Accurate detection of the time instant at which a system changes its internal structures has become a tremendously significant mission, beneficial to fully understanding the underlying mechanisms of evolving systems, and adequately modeling and predicting the dynamics of the systems as well. In real-world applications, due to a lack of prior knowledge on the explicit equations of evolving systems, an open challenge is how to develop a practical and model-free method to achieve the mission based merely on the time-series data recorded from real-world systems. here, we develop such a model-free approach, named temporal change-point detection(TCD), and integrate both dynamical and statistical methods to address this important challenge in a novel way. The proposed TCD approach, basing on exploitation of spatial information of the observed time series of high dimensions, is able not only to detect the separate change points of the concerned systems without knowing, a priori, any information of the equations of the systems, but also to harvest all the change points emergent in a relatively high-frequency manner, which cannot be directly achieved by using the existing methods and *** effectiveness is comprehensively demonstrated using the data from the representative complex dynamics and real-world systems from biology to geology and even to social science.

关键词： temporal systems time series change-point detection complex dynamical systems