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A Mode-switching Strategy of Droop Control for VSC-MTDC Systems Considering Maximum DC Voltage Regulation Capability

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 903-912页

作者： Yizhen Wang Fengliang qiu Zhongguan Wang Yirun Ji Zhengguang Chen Chengshan Wang Key Laboratory of Smart Grid of Ministry of Education Tianjin UniversityTianjin 300072China Electric Power Research Institute of State Grid JiBei Electric Power Co.Ltd. Beijing 100045China State Grid Corporation of China Beijing 100031China IEEE

To achieve the goal of carbon neutrality,renewable energy integration through a voltage source converter based multi-terminal direct current(VSC-MTDC)system has been identified as a promising *** tackle the significant DC voltage over-limit problem in a VSC-MTDC system during disturbances,this paper proposes a mode-switching strategy of droop control considering maximum DC voltage regulation *** close relationship between node injection powers and node DC voltages in the MTDC system is elaborated,and the most effective regulation approach of local injection power for limiting DC voltage deviation is *** operating point trajectories of different droop control explains that the DC voltage deviation can be minimized by fully utilizing the capacity of ***,the mode-switching strategy with the maximum DC voltage regulation capability is realized by the switching between the voltage droop control and the constant maximum power *** addition,a mode recovery process and a smooth switching method are developed to make converters regain the capability of maintaining DC voltage and reduce power fluctuation during mode switching,***,three cases are investigated to verify the effectiveness of the proposed mode-switching *** with simulation results of the conventional droop control and the DC voltage deviation-dependent droop control,better performance of transient and steady-state DC voltage deviation is achieved through the proposed strategy.

关键词： Droop control maximum DC voltage regulation capability mode-switching VSC-MTDC

Clustering for Bivariate Functional Data

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 613-629页

作者： Shi-yun CAO Yan-qiu ZHOU Yan-ling WAN Tao ZHANG School of Science Guangxi University of Science and TechnologyLiuzhou 545006China School of Marxism Guangxi University of Science and TechnologyLiuzhou 545006China Key Laboratory of Intelligent Information Processing and Graph Processing Guangxi University of Science and TechnologyLiuzhou 545006China

In this paper,we consider the clustering of bivariate functional data where each random surface consists of a set of curves recorded repeatedly for each *** k-centres surface clustering method based on marginal functional principal component analysis is proposed for the bivariate functional data,and a novel clustering criterion is presented where both the random surface and its partial derivative function in two directions are *** addition,we also consider two other clustering methods,k-centres surface clustering methods based on product functional principal component analysis or double functional principal component *** results indicate that the proposed methods have a nice performance in terms of both the correct classification rate and the adjusted rand *** approaches are further illustrated through empirical analysis of human mortality data.

关键词： bivariate functional data -centres surface clustering functional principal component analysis partial derivative function

Clinical risk factors for preterm birth and evaluating maternal psychology in the postpartum period

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World Journal of Psychiatry 2024年第5期14卷 661-669页

作者： Jia-Jun Chen Xue-Jin Chen qiu-Min She Jie-Xi Li qiu-Hong Luo Department of Clinical Laboratory Shenzhen Bao’an District Songgang People’s HospitalShenzhen 518000Guangdong ProvinceChina Department of Otolaryngology Head and Neck Surgery Outpatient Shenzhen Children’s HospitalShenzhen 518000Guangdong ProvinceChina Department of Prevention and Health Care Shenzhen Bao’an District Songgang People’s HospitalShenzhen 518000Guangdong ProvinceChina Department of Obstetrics Shenzhen Bao’an District Songgang People’s HospitalShenzhen 518000Guangdong ProvinceChina

BACKGROUND Although the specific pathogenesis of preterm birth(PTB)has not been thoroughly clarified,it is known to be related to various factors,such as pregnancy complications,maternal socioeconomic factors,lifestyle habits,reproductive history,environmental and psychological factors,prenatal care,and nutritional *** has serious implications for newborns and families and is associated with high mortality and ***,the prediction of PTB risk can facilitate early intervention and reduce its resultant adverse *** To analyze the risk factors for PTB to establish a PTB risk prediction model and to assess postpartum anxiety and depression in *** A retrospective analysis of 648 consecutive parturients who delivered at Shenzhen Bao’an District Songgang People’s Hospital between January 2019 and January 2022 was *** to the diagnostic criteria for premature infants,the parturients were divided into a PTB group(n=60)and a full-term(FT)group(n=588).Puerperae were assessed by the Self-rating Anxiety Scale(SAS)and Self rating Depression Scale(SDS),based on which the mothers with anxiety and depression symptoms were screened for further *** factors affecting PTB were analyzed by univariate analysis,and the related risk factors were identified by logistic *** According to univariate analysis,the PTB group was older than the FT group,with a smaller weight change and greater proportions of women who underwent artificial insemination and had gestational diabetes mellitus(P<0.05).In addition,greater proportions of women with reproductive tract infections and greater white blood cell(WBC)counts(P<0.05),shorter cervical lengths in the second trimester and lower neutrophil percentages(P<0.001)were detected in the PTB group than in the FT *** PTB group exhibited higher postpartum SAS and SDS scores than did the FT group(P<0.0001),with a higher number of mothers experiencing anxiety and depress

关键词： Preterm birth Risk factors Postpartum psychological state Risk model Prediction

Hydrogen production from hydrolysis of NaBH_(4) solution over Co-Fe-B@g-C_(3)N_(4)/NF thin film catalyst

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Rare Metals 2024年第6期43卷 2648-2659页

作者： Yan Wang Jia-Xin Ma Jian Ren Di Zhang Feng-Yan Xu Ke Zhang Zhong-qiu Cao qiu-Ju Sun Guo-De Li Shi-Wei Wu Hong-Hui Chen College of Chemistry and Chemical Engineering Shenyang Normal UniversityShenyang 110034China Experimental Center Shenyang Normal UniversityShenyang 110034China Hunan Shande Energy Storage New Materials Research Institute Limited Company Changde 415000China

In this study,the double loaded Co-Fe-B@g-C_(3)N_(4)/NF(NF:Ni foam)thin film catalysts were prepared for the first time via chemical deposition method at room *** optimizing the reducing agent concentration to 0.9 mol·L^(-1),the as-obtained Co-Fe-B@g-C_(3)N_(4)/NF exhibited the twisted ribbon structure with more distinct three-dimensional hierarchy and the smaller particle size,showing the good catalytic property for the hydrolysis of NaBH_(4)*** H_(2)generation rate of Co-Fe-B@g-C_(3)N_(4)/NF and binary Co-B@g-C_(3)N_(4)/NF under visible light irradiation surpassed the value under natural *** apparent activation energy of Co-Fe-B@g-C_(3)N_(4)/NF(45.0 kJ·mol^(-1))under visible light irradiation was obviously reduced when compared with the natural condition(48.4 kJ·mol^(-1))and binary Co-B@g-C_(3)N_(4)/NF(60.6 kJ·mol^(-1))under visible light ***,the catalytic performance of the optimized Co-Fe-B@g-C_(3)N_(4)/NF thin film catalyst was superior to most of the reported non-noble metal and even noble metal ***,it illustrated that the catalytic H_(2)production performance of Co-Fe-B@g-C_(3)N_(4)/NF thin film was distinctly improved after the introduction of light and multicomponent recombination.

关键词： Sodium borohydride Co-Fe-B@g-C_(3)N_(4)/NF catalyst Chemical deposition Hydrogen production

Thymic carcinoid with multiple bone metastases:A case report

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World Journal of Clinical Cases 2024年第13期12卷 2275-2280页

作者： Chun-Qiao Chen Ming-Yue Huang Min Pan qiu-qiu Chen Fei-Fei Wei Hui Huang Department of Oncology People’s Hospital of GuilinGuilin 541000Guangxi Zhuang Autonomous RegionChina

BACKGROUND Thymic carcinoid(TC)is a rare entity among anterior mediastinal *** are neuroendocrine carcinomas that constitute approximately 2%–5%of all thymic epithelial *** SUMMARY The study reported a rare TC with multiple bone metastases.A 77-year-old man presented with a 2-month history of lower back pain and weight loss of 5 *** resonance imaging scans revealed damage to the lumbar spine,sacrocaudal vertebrae and iliac crest,suggesting bone metastasis;computed tomography(CT)scan of the thorax showed a calcified anterior mediastinal mass;positron emission tomography-CT demonstrated multiple abnormal bone signals;and laboratory work-up showed no endocrine ***-needle aspiration biopsy revealed predominantly single small,round to oval cells with scant cytoplasm and some loose clusters,suggesting endocrine *** pathological diagnosis was atypical carcinoid,which tend to originate from the thymus and was classified as intermediate-highly *** patient underwent anlotinib-targeted ***(12 mg)was administered daily for 2 wk,after which the patient was allowed to rest for 21 ***-up CT after one year demonstrated that the tumor had shrunk by approximately 29%after *** has a long stable disease benefit of more than 2.5 *** These findings demonstrated that anlotinib is a promising treatment regimen for patients with TC and multiple bone metastases.

关键词： Thymic carcinoid Anlotinib Multitargeted tyrosine kinase inhibitor Bone metastasis Case report

Reconstruction of biomimetic ionic channels within covalent organic frameworks for ultrafast and selective uranyl capture

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Science China Chemistry 2024年第10期67卷 3423-3431页

作者： Cheng-Rong Zhang Xiao-Juan Chen Cheng-Peng Niu Cheng Meng Shun-Mo Yi Xin Liu Jia-Xin Qi qiu-Xia Luo Ru-Ping Liang Jian-Ding qiu State Key Laboratory of Nuclear Resources and Environment East China University of Technology College of Chemistry and Chemical Engineering Nanchang University

The efficient extraction of uranium, as the primary component of nuclear energy, holds significant implications. Drawing inspiration from the charge interaction observed in biological ion channels, we encapsulated negatively charged polystyrene sulfonate(PSS) or sodium polystyrene carboxylate(PVBA) into the nanochannels of amidoxime functionalized covalent organic framework(COF-AO) in-situ to alter the cavity environment of COF-AO. The synthesized COF-AO-PSS and COF-AO-PVBA are used for ultra-fast and highly selective uranium recovery. The negatively charged PSS/PVBA was confined in the COF-AO channel providing the driving force for uranium transport and blocking other ions, thus creating a highly selective “uranium highway”. Additionally, introducing sulfonate groups or carboxyl groups into COF-AO offers supplementary coordination environments and weak interactions with uranium. Due to charge-assisted migration and various interaction mechanisms, both COF-AO-PSS and COF-AO-PVBA exhibit faster adsorption kinetics and higher selectivity compared to COF-AO alone. Their adsorption capacities are 3.8 times and 2.4 times that of COF-AO alone respectively which highlights the necessity for constructing biomimetic ion channels in uranium adsorption processes. This work presents a bionic adsorbent based on covalent organic frameworks(COFs) for the first time, overcoming environmental and equipment limitations associated with traditional photocatalysis and electrocatalysis methods for uranium capture, opening up new avenues for designing multifunctional materials that mimic biological systems.

关键词： covalent organic frameworks Uranium biomimetic ion-channels adsorption

Coupling coordinated development among digital economy,regional innovation,and talent employment:A case study in the Hangzhou Metropolitan Circle,China

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Regional Sustainability 2024年第1期5卷 93-106页

作者： qiu Luyi Sharina OSMAN HUA Yidi Department of International Trade and Economics Ningbo PolytechnicNingbo315800China Business School Universiti Kuala LumpurKuala Lumpur50250Malaysia Research Institute of Digital Culture and Tourism Ningbo PolytechnicNingbo315800China School of International Studies University of Nottingham Ningbo ChinaNingbo315400China

Coordinative development across various systems,particularly the economic,social,cultural,and human resources subsystems,is a key aspect of urban sustainability and has a direct impact on the quality of *** Hangzhou Metropolitan Circle,comprising Hangzhou City,Huzhou City,Jiaxing City,and Shaoxing City,was the first metropolitan circle approved by the National Development and Reform Commission(NDRC)as a demonstration of economic transformation in *** evaluate the coupling coordination degree of the four cities and analyze the coordinative development in three systems(including digital economy,regional innovation,and talent employment),we collected panel data during 2015–2022 from these four *** development level of the three systems was evaluated by the standard deviation method and comprehensive development *** results are as follows:(1)the level of coupling coordinated development of the three systems in the Hangzhou Metropolitan Circle was relatively low;(2)the coupling coordination degree of the four cities in the Hangzhou Metropolitan Circle showed significant regional differences,among which Hangzhou City was in the leading position,and Huzhou,Jiaxing,and Shaoxing cities made steady but slow progress in the coupling development of the three systems;and(3)the development of digital economy and talent employment needs to be *** study contributes to the coordinative development of Hangzhou Metropolitan Circle by innovatively focusing on the coupling coordination relationship among digital economy,regional innovation,and talent employment,which also meets the industrial layout of Hangzhou Metropolitan *** this way,the optimal allocation and sustainable development of digital economy,regional innovation,and talent employment in the Hangzhou Metropolitan Circle can be achieved.

关键词： Digital economy Regional innovation Talent employment Coupling coordination degree Hangzhou Metropolitan Circle

Controlling solid form and crystal habit of triphenylmethanol by antisolvent crystallization in a microfluidic device

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Chinese Chemical Letters 2024年第4期35卷 393-398页

作者： Jun Lu Jinrui Yan Yaohao Guo Junjie qiu Shuangliang Zhao Bo Bao East China University of Science and Technology Shanghai 200237China Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology and School of Chemistry and Chemical Engineering Guangxi UniversityNanning 530004China

Crystal habit and crystal form are critical elements in determining product properties and functions. In this work, we developed a microfluidic antisolvent crystallization technique to rapidly screen and accurately control the solid form and crystal habit of triphenylmethanol(Ph_(3)COH). This advanced technique separates the primary mixing of solutions from crystal formation(nucleation and growth) by introducing the microfluidic device, avoiding clogging in microchannels to obtain high-quality crystals. The results show that we can achieve controllable preparation of pure 2Ph_(3)COH·DMSO(DMSO solvate), pure Ph_(3)COH(form β), and mixed crystals with different mass ratios. Moreover, the microscale can prompt the DMSO solvate to grow into hexagonal sheet-like and bulk crystals. We can regulate the aspect ratio of hexagonal sheet-like crystals in binary solvents and control the crystal habit of the form β to transition between long needle-like shapes and short hexagonal prisms in DMF-H_(2)O. Meanwhile, we revealed that the solvent ratio, the antisolvent flow rate, and the initial concentration of Ph_(3)COH are the main factors affecting the solid form selectivity and morphology transition. Such a novel method would be considered as a promising technique to be extended to screen and control key crystallization parameters of other substances.

关键词： Microfluidics Triphenylmethanol Antisolvent crystallization Crystal habit Solid form

Thermally Conductive,Healable Glass Fiber Cloth Reinforced Polymer Composite based onβ-Hydroxyester Bonds Crosslinked Epoxy with Improved Heat Resistance

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Chinese Journal of Polymer Science 2024年第5期42卷 643-654,I0009页

作者： Fang Chen Xiao-Yan Pang Ze-Ping Zhang Min-Zhi Rong Ming-qiu Zhang Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education GD HPPC LabIGCMESchool of ChemistrySun Yat-sen UniversityGuangzhou510275China Guangdong Provincial Laboratory of Chemistry and Fine Chemical Engineering Jieyang Center Jieyang515200China

To simultaneously endow thermal conductivity,high glass transition temperature(Tg)and healing capability to glass fiber/epoxy(GFREP)composite,dynamic crosslinked epoxy resin bearing reversibleβ-hydroxyl ester bonds was reinforced with boron nitride nanosheets modified glass fiber cloth(GFC@BNNSs).The in-plane heat conduction paths were constructed by electrostatic self-assembly of polyacrylic acid treated GFC and polyethyleneimine decorated ***,the GFC@BNNSs were impregnated with the mixture of lower concentration(3-glycidyloxypropyl)trimethoxysilane grafted BN micron sheets,3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and hexahydro-4-methylphthalic anhydride,which accounted for establishing the through-plane heat transport pathways and avoiding serious deterioration of mechanical *** resultant GFREP composite containing less boron nitride particles(17.6 wt%)exhibited superior in-plane(3.29 W·m^(-1)·K^(-1))and through-plane(1.16 W·m^(-1)·K^(-1))thermal conductivities,as well as high Tg of 204℃(Tg of the unfilled epoxy=177℃).The reversible transesterification reaction enabled closure of interlaminar cracks within the composite,achieving decent healing efficiencies estimated by means of tensile strength(71.2%),electrical breakdown strength(83.6%)and thermal conductivity(69.1%).The present work overcame the disadvantages of conventional thermally conductive composites,and provided an efficient approach to prolong the life span of thermally conductive GFREP laminate for high-temperature resistant integrated circuit application.

关键词： Thermally conductive composites Boron nitride High-temperature resistance β-Hydroxyl ester bond Healing