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Convexification of hybrid AC-DC Optimal Power Flow with Line-Commutated Converters

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CSEE journal of Power and Energy Systems 2024年第2期10卷 617-628页

作者： hongyuan Liang Zhigang Li j.h.Zheng Q.h.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China

Line-commutated converter (LCC)-based high-voltage DC (hVDC) systems have been integrated with bulk AC power grids for interregional transmission of renewable power. The nonlinear LCC model brings additional nonconvexity to optimal power flow (OPF) of hybrid AC-DC power grids. A convexification method for the LCC station model could address such nonconvexity but has rarely been discussed. We devise an equivalent reformulation for classical LCC station models that facilitates second-order cone convex relaxation for the OPF of LCC-based AC-DC power grids. We also propose sufficient conditions for exactness of convex relaxation with its proof. Equivalence of the proposed LCC station models and properties, exactness, and effectiveness of convex relaxation are verified using four numerical simulations. Simulation results demonstrate a globally optimal solution of the original OPF can be efficiently obtained from relaxed model.

关键词： AC-DC power system convex relaxation linecommutated converter optimal power flow second-order cone programming

Observability Analysis of Integrated Electricity and heating Systems with Thermal Quasi-dynamics in Pipelines

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CSEE journal of Power and Energy Systems 2024年第3期10卷 1145-1158页

作者： Zhigang Li Wenjian Zheng junbo Zhao j.h.Zheng Q.h.Wu School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China Fuzhou Changle District Power Supply Company of State Grid Fujian Electric Power Co. Ltd.Fuzhou 350000China Department of Electrical and Computer Engineering University of ConnecticutStorrsCT 06269USA CSEE IEEE

Observability analysis(OA)is vital to obtaining the available input measurements of state estimation(SE)in an integrated electricity and heating system(IEhS).Considering the thermal quasi-dynamics in pipelines,the measurement equations in heating systems are dependent on the estimated results,leading to an interdependency between OA and *** OA methods require measurement equations be known exactly before SE is performed,and they are not applicable to *** bridge this gap,a scenario-based OA scheme for IEhSs is devised that yields reliable analysis results for a predefined set of time-delay scenarios to cope with this *** its core procedure,the observable state identification and observability restoration are formulated in terms of integer linear *** tests are conducted to demonstrate the validity and superiority of the proposed formulation.

关键词： Integrated electricity and heating system measurement observability analysis state estimation thermal quasi-dynamics

Prenatal and postnatal factors associated with sudden infant death syndrome:an umbrella review of meta-analyses

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World journal of Pediatrics 2024年第5期20卷 451-460页

作者： Tae hyeon Kim hyeri Lee Selin woo hayeon Lee jaeyu Park Guillaume Fond Laurent Boyer jong woo hahn jiseung Kang Dong Keon Yon Department of Medicine Kyung Hee University College of MedicineSeoulSouth Korea Center for Digital health Medical Science Research InstituteKyung Hee University College of MedicineSeoulSouth Korea Department of Regulatory Science Kyung Hee UniversitySeoulSouth Korea Department of Biomedical Engineering Kyung Hee UniversityYonginSouth Korea CEReSS-health Service Research and Quality of Life Center Assistance Publique des Hôpitaux de MarseilleAix-Marseille UniversityMarseilleFrance Department of Pediatrics Seoul National University College of MedicineSeoulSouth Korea Department of Pediatrics Seoul National University Bundang HospitalSeongnamSouth Korea Department of Anesthesia Critical Care and Pain MedicineMassachusetts General Hospital14913th StreetRoom 4140CharlestownBostonMAUSA Division of Sleep Medicine Harvard Medical SchoolBostonMAUSA Department of Pediatrics Kyung Hee University Medical CenterKyung Hee University College of Medicine23 Kyungheedae-roDongdaemun-guSeoul02447South Korea Department of Precision Medicine Kyung Hee University College of MedicineSeoulSouth Korea

Background Comprehensive quantitative evidence on the risk and protective factors for sudden infant death syndrome(SIDS)effects is *** investigated the risk and protective factors related to *** We conducted an umbrella review of meta-analyses of observational and interventional studies assessing SIDS-related ***/MEDLINE,Embase,EBSCO,and Google Scholar were searched from inception until january 18,*** extraction,quality assessment,and certainty of evidence were assessed by using A Measurement Tool Assessment Systematic Reviews 2 following PRISMA *** to observational evidence,credibility was graded and classified by class and quality of evidence(CE;convincing,highly suggestive,suggestive,weak,or not significant).Our study protocol was registered with PROSPERO(CRD42023458696).The risk and protective factors related to SIDS are presented as equivalent odds ratios(eORs).Results We identified eight original meta-analyses,including 152 original articles,covering 12 unique risk and protective factors for SIDS across 21 countries/regions and five *** risk factors,including prenatal drug exposure[eOR=7.84(95%CI=4.81–12.79),CE=highly suggestive],prenatal opioid exposure[9.55(95%CI=4.87–18.72),CE=suggestive],prenatal methadone exposure[9.52(95%CI=3.34–27.10),CE=weak],prenatal cocaine exposure[4.38(95%CI=1.95–9.86),CE=weak],prenatal maternal smoking[2.25(95%CI=1.95–2.60),CE=highly suggestive],postnatal maternal smoking[1.97(95%CI=1.75–2.22),CE=weak],bed sharing[2.89(95%CI=1.81–4.60),CE=weak],and infants found with heads covered by bedclothes after last sleep[11.01(95%CI=5.40–22.45),CE=suggestive],were *** the other hand,three protective factors,namely,breastfeeding[0.57(95%CI=0.39–0.83),CE=non-significant],supine sleeping position[0.48(95%CI=0.37–0.63),CE=suggestive],and pacifier use[0.44(95%CI=0.30–0.65),CE=weak],were also *** Based on the evidence,we propose several risk and protecti

关键词： Infant Protective factor Risk factor Sudden infant death syndrome Umbrella review

Synthesis of porous flower-like SnO_(2)/CdSnO_(3) microstructures with excellent sensing performances for volatile organic compounds

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Frontiers of Materials Science 2024年第1期18卷 45-57页

作者： jie Wan Gang Wang haibo Ren jiarui huang Sang woo joo School of Materials Science and Engineering Anhui Polytechnic UniversityWuhu 241000China Key Laboratory of Functional Molecular Solids of the Ministry of Education College of Chemistry and Materials ScienceAnhui Normal UniversityWuhu 241002China School of Mechanical Engineering Yeungnam UniversityGyeongsanGyeoungbuk 712749Republic of Korea

Porous flower-like SnO_(2)/CdSnO_(3) microstructures self-assembled by uniform nanosheets were synthesized using a hydrothermal process followed by calcination,and the sensing performance was measured when a gas sensor,based on such microstructures,was exposed to various volatile organic compound(VOC)*** response value was found to reach as high as 100.1 when the SnO_(2)/CdSnO_(3) sensor was used to detect 100 ppm formaldehyde gas,much larger than those of other tested VOC gases,indicating the high gas sensitivity possessed by this sensor especially in the detection of formaldehyde ***,the response/recovery process was fast with the response time and recovery time of only 13 and 21 s,*** excellent gas sensing performance derive from the advantages of SnO_(2)/CdSnO_(3),such as abundant n-n heterojunctions built at the interface,high available specific surface area,abundant porosity,large pore size,and rich reactive oxygen species,as well as joint effects arising from SnO_(2) and CdSnO_(3),suggesting that such porous flower-like SnO_(2)/CdSnO_(3) microstructures composed of nanosheets have a high potential for developing gas sensors.

关键词： SnO_(2)/CdSnO_(3) porous flower-like microstructure volatile organic gas sensingproperty gas sensor

Dissociation cross sections ofψ(3770),ψ(4040),ψ(4160),andψ(4415)mesons with nucleons

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Communications in Theoretical Physics 2024年第4期76卷 93-112页

作者： Ruo-Qing Ding Xiao-Ming Xu h j Weber Department of Physics Shanghai UniversityBaoshanShanghai 200444China Department of Physics University of VirginiaCharlottesvilleVA 22904United States of America

We study the dissociation of ψ(3770), ψ(4040), ψ(4160), and ψ(4415) mesons in collision with nucleons, which takes place in high-energy proton-nucleus collisions. The quark interchange between a nucleon and a ■ meson leads to the dissociation of the ■ meson. We consider the reactions:■, and■, where R stands for ψ(3770), ψ(4040), ψ(4160), or ψ(4415). A reaction of a neutron and a ■ meson corresponds to a reaction of a proton and the ■ meson by replacing the up quark with the down quark and vice versa. Transition-amplitude formulas are derived from the S-matrix *** cross sections are calculated with the transition amplitudes for scattering in the prior form and in the post form. The cross sections relate to nodes in the radial wave functions of ψ(3770), ψ(4040), ψ(4160), and ψ(4415) mesons.

关键词： inelastic nucleon-charmonium scattering quark interchange relativistic constituent quark potential model

Increasing concentrations of dietary threonine, tryptophan, and glycine improve growth performance and intestinal health with decreasing stress responses in broiler chickens raised under multiple stress conditions

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ANIMAL NUTRITION 2024年第3期18卷 145-153页

作者： Kim, hyun woo Kim, jong hyuk han, Gi Ppeum Kil, Dong Yong Chung Ang Univ Dept Anim Sci & Technol Anseong 17546 South Korea Chungbuk Natl Univ Dept Anim Sci Cheongju 28644 South Korea

The current study aimed to compare the effects of increasing concentrations of dietary threonine (Thr), tryptophan (Trp), and glycine (Gly) on growth performance, stress biomarkers, and intestinal function in broiler chickens under multiple stress conditions. Five hundred sixty broiler chickens at 21 d old were randomly allotted to 5 treatments with 8 replicates. Birds in a positive control (PC) treatment were raised under low stock density (16.9 birds/m(2) per cage) with recommended environmental conditions, whereas birds in 4 treatments were subjected to multiple stress conditions: a cyclic heat stress of 30 +/- 0.3 degrees C for 10 h and 23 +/- 0.2 degrees C for 14 h per day with high stock density (25.3 birds/m(2) per cage). A basal diet was assigned to both PC and negative control (NC) treatments. Three additional diets were individually formulated to contain double concentrations of digestible Thr, Trp, or Gly + Ser compared with their concentrations in the basal diet. The experiment lasted for 14 d. Results showed that NC treatment had less growth performance (P jejunal goblet cell counts (P = 0.018), and trans-epithelial electrical resistance (TEER; P her corticosterone (CORT) concentrations than PC treatment. Thr treatment showed the least (P hr, Trp, and Gly treatments had less (P = 0.026) feather CORT concentrations, but had greater (P han NC treatment. In conclusion, increasing concentrations of dietary Thr, Trp, or Gly improve the growth performance and intestinal health in broiler chickens with decreasing stress response under multiple stress conditions.

关键词： Broiler chicken Glycine Multiple stress Threonine Tryptophan MEAT QUALITY hEAT-STRESS BEhAVIORAL-RESPONSES OXIDATIVE STATUS SUPPLEMENTATION MICROFLORA INTEGRITY PROTEIN METABOLISM EXPRESSION

On an isotropic porous solid cylinder:the analytical solution and sensitivity analysis of the pressure

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1499-1522页

作者： h.ASGhARI L.MILLER R.PENTA j.MERODIO Departamento de Matematica Aplicada a las TIC ETS de Ingenieria de Sistemas InformaticosUniversidad Politecnica de MadridMadrid 28031Spain School of Mathematics and Statistics University of GlasgowGlasgow G128QQU.K.

Within this work,we perform a sensitivity analysis to determine the influence of the material input parameters on the pressure in an isotropic porous solid *** provide a step-by-step guide to obtain the analytical solution for a porous isotropic elastic cylinder in terms of the pressure,stresses,and elastic *** obtain the solution by performing a Laplace transform on the governing equations,which are those of Biot's poroelasticity in cylindrical polar *** enforce radial boundary conditions and obtain the solution in the Laplace transformed domain before reverting back to the time *** sensitivity analysis is then carried out,considering only the derived pressure *** analysis finds that the time t,Biot's modulus M,and Poisson's ratio ν have the highest influence on the pressure whereas the initial value of pressure P_(0) plays a very little role.

关键词： sensitivity analysis Laplace transform cylindrical polar coordinate Biot's modulus cylinder

Editorial for the Special Issue on Emerging Technology and Advanced Application of Nondestructive Detection for Power Equipment

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Chinese journal of Electrical Engineering 2024年第1期10卷 1-2页

作者： Li j. Mei h. Li S. Tianjin University China Tsinghua Shenzhen International Graduate School China Lanzhou jiaotong University China

The rapid development of clean and renewable energy technologies represented by wind and solar energy,as well as the continuous growth of load demand,have put forward higher requirements for the safe operation of the power *** performance of power equipment based on traditional dielectric materials is often limited by various defects generated during molding,transportation,assembly,and operation,which cannot meet the reliability requirements of power systems in the new *** detection is an essential technical method in industrial development,which can detect and evaluate the defect and damage status of in-service equipment,key components,and materials without damaging the object.

关键词： service Application operation

Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

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journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： h.T.jeong S.W.Lee W.j.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)with a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the hCPαphase,were examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy was achieved by employing high-ratio differential speed *** best superplasticity was achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),where tensile elongations of 550±600%were *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size was observed at temperatures above 573 ***,it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding,while at high strain rates,lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation *** was concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it was observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps were constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy Superplasticity Severe plastic deformation Grain size Grain growth