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Impedance Analysis Considering Unstable Subsystem Poles for MMC-HVDC-based Wind Farm Integration System

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CSEE Journal of Power and Energy Systems 2022年第2期8卷 634-639页

作者： ke ji Hui Pang Shan liu Guangfu Tang China Electric Power Research Institute Beijing100192China Global Energy Interconnection Research Institute Beijing 102211China

Employing the AC/DC impedance analysis method,extensive research has been conducted on issues pertaining to harmonic resonance observed in wind farm-connected MMCHVDC systems over the past 5 years.In general,this method divides the studied system into two subsystems at AC and DC sections.Subsequently,the impedance produced by these subsystems can be used to determine the system stability by implementing Nyquist criterion or generalized Nyquist stability criterion.However,the existing impedance analysis methods usually assume the subsystems to be stable and disregard certain special cases with potentially unstable subsystems,where the unstable poles of these subsystems must be evaluated before applying Nyquist criterion.In view of this consideration,a simplified method for identifying unstable subsystem poles is presented in this paper.Hence,the shortcoming of existing impedance analyses is rectified by considering the unstable subsystem poles.The proposed method and the stability analyses are validated by the electromagnetic transient simulation performed in PSCAD/EMTDC.

关键词： AC/DC side impedance method harmonic resonance MMC-HVDC small-signal stability wind farm

Effects of anesthetic depth on postoperative pain and delirium:a meta-analysis of randomized controlled trials with trial sequential analysis

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Chinese Medical Journal 2022年第23期135卷 2805-2814页

作者： Yuqin Long Xiaomei Feng Hong liu Xisheng Shan Fuhai ji ke Peng Department of Anesthesiology First Affiliated Hospital of Soochow UniversitySuzhouJiangsu 215006China Institute of Anesthesiology Soochow UniversitySuzhouJiangsu 215006China Department of Anesthesiology University of Utah HealthSalt Lake CityUTUSA Department of Anesthesiology and Pain Medicine University of California Davis HealthSacramentoCA

Background:Whether anesthetic depth affects postoperative outcomes remains controversial.This meta-analysis aimed to evaluate the effects of deepvs.light anesthesia on postoperative pain,cognitive function,recovery from anesthesia,complications,and mortality.Methods:PubMed,EMBASE,and Cochrane CENTRAL databases were searched until January 2022 for randomized controlled trials comparing deep and light anesthesia in adult surgical patients.The co-primary outcomes were postoperative pain and delirium(assessed using the confusion assessment method).We conducted a meta-analysis using a random-effects model.We assessed publication bias using the Begg’s rank correlation test and Egger’s linear regression.We evaluated the evidence using the trial sequential analysis and Grading of Recommendations Assessment,Development and Evaluation(GRADE)methodology.We conducted subgroup analyses for pain scores at different postoperative time points and delirium according to cardiac or non-cardiac surgery.Results:A total of 26 trials with 10,743 patients were included.Deep anesthesia compared with light anesthesia(a mean difference in bispectral index of-12 to-11)was associated with lower pain scores at rest at 0 to 1 h postoperatively(weighted mean difference=-0.72,95%confidence interval[CI]=-1.25 to-0.18,P=0.009;moderate-quality evidence)and an increased incidence of postoperative delirium(24.95%vs.15.92%;risk ratio=1.57,95%CI=1.28-1.91,P<0.0001;high-quality evidence).No publication bias was detected.For the exploratory secondary outcomes,deep anesthesia was associated with prolonged postoperative recovery,without affecting neurocognitive outcomes,major complications,or mortality.In the subgroup analyses,the deep anesthesia group had lower pain scores at rest and on movement during 24 h postoperatively,without statistically significant subgroup differences,and deep anesthesia was associated with an increased incidence of delirium after non-cardiac and cardiac surgeries,without statistically significant subgroup differences.Conclusion

关键词： Anesthetic depth GRADE level of evidence Postoperative delirium Postoperative pain Trial sequential analysis

Probing the processing of facial expressions in monkeys via time perception and eye tracking

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动物学研究(英文) 2023年第5期44卷 882-893页

作者： Xin-He liu Lu Gan Zhi-Ting Zhang Pan-ke Yu ji Dai Shenzhen Technological Research Center for Primate Translational Medicine Shenzhen-Hong Kong Institute of Brain ScienceShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenGuangdong 518055China CAS key Laboratory of Brain Connectome and Manipulation Brain Cognition and Brain Disease InstituteShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenGuangdong 518055China Guangdong Provincial key Laboratory of Brain Connectome and Behavior Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenGuangdong 518055China Research Center for Medical Artificial Intelligence Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenGuangdong 518055China University of Chinese Academy of Sciences Beijing 100049China

Accurately recognizing facial expressions is essential for effective social interactions.Non-human primates(NHPs)are widely used in the study of the neural mechanisms underpinning facial expression processing,yet it remains unclear how well monkeys can recognize the facial expressions of other species such as humans.In this study,we systematically investigated how monkeys process the facial expressions of conspecifics and humans using eye-tracking technology and sophisticated behavioral tasks,namely the temporal discrimination task(TDT)and face scan task(FST).We found that monkeys showed prolonged subjective time perception in response to Negative facial expressions in monkeys while showing longer reaction time to Negative facial expressions in humans.Monkey faces also reliably induced divergent pupil contraction in response to different expressions,while human faces and scrambled monkey faces did not.Furthermore,viewing patterns in the FST indicated that monkeys only showed bias toward emotional expressions upon observing monkey faces.Finally,masking the eye region marginally decreased the viewing duration for monkey faces but not for human faces.By probing facial expression processing in monkeys,our study demonstrates that monkeys are more sensitive to the facial expressions of conspecifics than those of humans,thus shedding new light on inter-species communication through facial expressions between NHPs and humans.

关键词： Monkey Facial expression Time perception Eye-tracking Pupil size

Inhibition of Abnormal Grain Growth in Stir Zone via In‑Situ Intermetallic Particle Formation During Friction Stir Welding of AA6061

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Acta Metallurgica Sinica(English Letters) 2023年第4期36卷 597-610页

作者： Xin Zou Cunli liu Muyang Deng ji Chen Lanting Zhang ke Chen School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai key Laboratory of Material Laser Processing and Modification Shanghai Jiao Tong UniversityShanghai 200240China Shanghai-FANUC Robotics CO. LTDShanghai 201906China

Abnormal grain growth(AGG)has been widely observed in many friction stir welded(FSWed)joints during post-weld heat treatment(PWHT).The coarse grain structure not only reduces the strength of the joint but also limits its usage in superplastic forming.Several methods have been reported in previous studies to inhibit AGG,but all of them can only mitigate AGG.Complete inhibition of AGG was not achieved.In the current research,AGG was widely observed during the PWHT of friction stir welded AA6061.Multi-pass FSW enhanced the thermal stability of the as-welded grain structure but did not eliminate the occurrence of AGG.A new welding method was developed with the ball-milled Al–Ti powder mixture introduced into the stir zone and proved effective in inhibiting AGG in FSWed AA6061 during PWHT.The adoption of 5-pass FSW with an alternate rotation mode succeeded in producing an AGG-free sample.Microscopic characterizations conducted in the stir zone showed an evolution of Al–Ti powder mixture into different particle formations and Al3Ti new phase.Quantitative analysis of the second phase particles(SPPs)in the stir zone confirmed the increases in both particle number and average size.The quantitative results fit well with Humphreys’grain growth model,which theoretically explains the mechanism for AGG inhibition,i.e.,the significantly enhanced particle pinning effect.

关键词： Abnormal grain growth Friction stir welding AA6061 Second phase particle Particle pinning

Characteristics and comfort evaluation of sinusoidal airflows by regulating motor rotating frequency of a floor fan

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Building Simulation 2022年第6期15卷 1035-1049页

作者： Chenqiu Du Hong liu Wei Yu Yu ji ke Yan Liyang Ruan Joint International Research Laboratory of Green Buildings and Built Environments(Ministry of Education) Chongqing UniversityChongqing400045China National Centre for International Research of Low-carbon and Green Buildings(Ministry of Science and Technology) Chongqing UniversityChongqing400045China

Increasing air movement by utilizing electric fans is among the common approaches for comfort and energy savings in buildings in summer;however,the use of electric fans is usually the forced constant airflow.This study reformed the one-chip computer program of a floor fan motor and simulated dynamic airflow through controlling the rotating frequency only.The flow field characteristics of constant,oscillated,sinusoidal airflows with periods of 10 s,30 s,60 s,100 s were measured.The comfort performance was evaluated by chamber experiments,with 20 subjects exposed to six airflow patterns under 30℃,70%RH.The results showed that the simulated sinusoidal airflows had relatively higher turbulence intensity(32%–37%)andβvalues(>0.4).While subjects’thermal sensations were not statistically significant among six airflows,their reported discomfort symptoms during 60 min exposure were reduced under sinusoidal airflows.The calculated convective heat transfer shared similar variations to instantaneous air velocity and skin temperature.A large fluctuation of 10–50 W/m^(2)and higher total convective heat loss(3000–3500 W/m^(2))were found for sinusoidal period 30 s.This study develops a new method to simulate varying air velocities through conveniently controlling the fan motor amplitude and frequency,and verifies the comfortable feelings to dynamic sinusoidal airflows.The work benefits to improve the performance of the current electric fans with lower costs and promote the applications of personal ventilation devices in buildings,thus optimizing human thermal comfort,reducing dependences on air conditionings and achieving building energy efficiency.

关键词： dynamic airflow floor fan sinusoidal law airflow field characteristics thermal perceptions

Identification and Bioactivities of Secondary Metabolites Derived from Endophytic Fungi Isolated from Ethnomedicinal Plants of Tujia in Hubei Province:A Review

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Natural Products and Bioprospecting 2021年第2期11卷 185-205页

作者： ke Ye Hong-Lian Ai ji-Kai liu School of Pharmaceutical Science South-Central University for NationalitiesWuhan 430074HubeiChina

Tujia is a national minority,inhabiting in the mountainous Wuling area in China.Since 1978,Tujia medicine has been studied,summarized and developed,leading to numerous achievements by Chinese researchers,such as the publishing of approximately 30 monographs of Tujia medicine.These publications are focused on summarizing and improving the theory of Tujia medicine and developing clinical therapies from this system of medicine.The shortage of natural medicinal plants used in Tujia medicine has created the need to discover new resources to replace them and protect endangered natural plant species.Endophytic fungi are one of the conservation options,are considered a source of new bioactive natural products,and are a renewable and inexhaustible source of new drugs and agrochemicals.This review summarizes 260 compounds from endophytic fungi that have been previously isolated from the medicinal plants of Tujia.These compounds include steroids,terpenoids,meroterpenoids,polyketides,alkaloids,peptides,aliphatic compounds,aromatic compounds,and heterocyclic compounds.

关键词： Tujia medicine Endophytic fungi Secondary metabolites Bioactivities

Identification of Dynamic Active Sites Among Cu Species Derived from MOFs@CuPc for Electrocatalytic Nitrate Reduction Reaction to Ammonia

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Nano-Micro Letters 2023年第8期15卷 20-34页

作者： Xue‑Yang ji ke Sun Zhi‑Kun liu Xinghui liu Weikang Dong Xintao Zuo Ruiwen Shao Jun Tao key Laboratory of Cluster Science of Ministry of Education School of Chemistry and Chemical EngineeringLiangxiang CampusBeijing Institute of TechnologyBeijing 102488People’s Republic of China Department of Chemistry Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Department of Materials Physics Saveetha School of EngineeringSaveetha Institute of Medical and Technical Sciences(SIMTS)ThandalamChennaiTamilnadu 602105India Beijing Advanced Innovation Center for Intelligent Robots and Systems and Institute of Engineering Medicine Beijing Institute of TechnologyBeijing 100081People’s Republic of China key Laboratory of Bio‑inspired Smart Interfacial Science and Technology of Ministry of Education School of ChemistryBeihang UniversityBeijing 100191People’s Republic of China

Direct electrochemical nitrate reduction reaction(NITRR)is a promising strategy to alleviate the unbalanced nitrogen cycle while achieving the electrosynthesis of ammonia.However,the restructuration of the high-activity Cu-based electrocatalysts in the NITRR process has hindered the identification of dynamical active sites and in-depth investigation of the catalytic mechanism.Herein,Cu species(single-atom,clusters,and nanoparticles)with tunable loading supported on N-doped TiO_(2)/C are successfully manufactured with MOFs@CuPc precursors via the pre-anchor and post-pyrolysis strategy.Restructuration behavior among Cu species is co-dependent on the Cu loading and reaction potential,as evidenced by the advanced operando X-ray absorption spectroscopy,and there exists an incompletely reversible transformation of the restructured structure to the initial state.Notably,restructured CuN_(4)&Cu_(4) deliver the high NH_(3) yield of 88.2 mmol h^(−1)g_(cata)^(−1) and FE(~94.3%)at−0.75 V,resulting from the optimal adsorption of NO_(3)^(−) as well as the rapid conversion of^(*)NH_(2)OH to^(*)NH_(2) intermediates originated from the modulation of charge distribution and d-band center for Cu site.This work not only uncovers CuN_(4)&Cu_(4) have the promising NITRR but also identifies the dynamic Cu species active sites that play a critical role in the efficient electrocatalytic reduction in nitrate to ammonia.

关键词： Metal-organic frameworks Copper phthalocyanine Electrocatalytic nitrate reduction reaction

Therapeutic effect of oridonin on mice with prostate cancer

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Asian Pacific Journal of Tropical Medicine 2016年第2期9卷 182-185页

作者： Ming Ming Feng-Yin Sun Wen-Tong Zhang Ji-Ke Liu Department of Pediatric Surgery Qilu Hospital of Shandong University Department of Pediatric Surgery Taian City Central Hospital Department of Pediatric Surgery Liaocheng Hospital

Objective: To investigate the therapeutic effect and the related mechanism of oridonin on mice with prostate cancer. Methods: Sixty BALB/C male nude mice were selected. A model of RM-1 cell transplantation tumor of prostate cancer was built by the subcutaneous inoculation of RM-1 cells. After that, those 60 experimental mice were randomly divided into groups A, B and C. Each group had 20 mice. Mice in group A were treated with 0.2 m L of normal saline(0.9%) by intraperitoneal injection once a day; mice in group B received intraperitoneal injection of 1.875 mg/m L of oridonin once a day; and mice in group C received intraperitoneal injection of 7.5 mg/m L of oridonin once a day. Mice in the three groups were treated uninterruptedly for 5 weeks and were all killed. Then, tumors were excised and weighed to calculate their growth inhibitory rate, volume increment and anti-tumor rate. Thymus and spleen of mice in the three groups were collected to calculate the thymus and spleen index. Immunohistochemical staining was applied to observe the expression of caspase-3 in prostate cancer tissue of mice of the three groups. Results: The qualities and volume increment of tumors in groups B and C were significantly lower than those of group A(P 0.05). Immumohistochemical staining revealed that the caspase-3 protein in prostate cancer tissue of mice of group A expressed negatively with colourless or light-colored karyon; while the caspase-3 protein in prostate cancer tissue of mice of group B expressed positively with dark-colored karyon, centralized distribution and granular sensation; a

关键词： Oridonin Prostate cancer RM-1 cells Caspase-3

A Novel Feature Selection Strategy Based on Salp Swarm Algorithm for Plant Disease Detection

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Plant Phenomics 2023年第2期5卷 209-225页

作者： Xiaojun Xie Fei Xia Yufeng Wu Shouyang liu ke Yan Huanliang Xu Zhiwei ji College of Artificial Intelligence Nanjing Agricultural UniversityNanjingJiangsu 210095China Center for Data Science and Intelligent Computing Nanjing Agricultural UniversityNanjingJiangsu 210095China State key Laboratory for Crop Genetics and Germplasm Enhancement Bioinformatics CenterAcademy for Advanced Interdisciplinary StudiesNanjing Agricultural UniversityNanjingJiangsu 210095China Academy for Advanced Interdisciplinary Studies Nanjing Agricultural UniversityNanjingJiangsu 210095China Department of the Built Environment College of Design and EngineeringNational University of Singapore4 Architecture DriveSingapore 117566Singapore

Deep learning has been widely used for plant disease recognition in smart agriculture and has proven to be a powerful tool for image classification and pattern recognition.However,it has limited interpretability for deep features.With the transfer of expert knowledge,handcrafted features provide a new way for personalized diagnosis of plant diseases.However,irrelevant and redundant features lead to high dimensionality.In this study,we proposed a swarm intelligence algorithm for feature selection[salp swarm algorithm for feature selection(SSAFS)]in image-based plant disease detection.SSAFS is employed to determine the ideal combination of handcrafted features to maximize classification success while minimizing the number of features.To verify the effectiveness of the developed SSAFS algorithm,we conducted experimental studies using SSAFS and 5 metaheuristic algorithms.Several evaluation metrics were used to evaluate and analyze the performance of these methods on 4 datasets from the UCI machine learning repository and 6 plant phenomics datasets from PlantVillage.Experimental results and statistical analyses validated the outstanding performance of SSAFS compared to existing state-of-the-art algorithms,confirming the superiority of SSAFS in exploring the feature space and identifying the most valuable features for diseased plant image classification.This computational tool will allow us to explore an optimal combination of handcrafted features to improve plant disease recognition accuracy and processing time.

关键词： Plant image redundant