检索结果-南通市图书馆

Chinese Journal of Aeronautics 2024年第10期37卷 435-444页

作者： Qi ZHONG Junxian WANG Enguang xu cheng YU Yanbiao LI College of Mechanical Engineering Zhejiang University of TechnologyHangzhou 310023China Key Laboratory of Special Purpose Equipment and Advanced Processing Technology Ministry of Education and Zhejiang ProvinceZhejiang University of TechnologyHangzhou 310023China

Hydraulic circuits with high speed on/off valve(HSV)for servo control have become commonplace in ***,the individual valve that is not volume-optimized results in a large total size of hydraulic control system,diminishing the *** address this issue,the high-precision equivalent reluctance model of the HSV is established by employing an equivalent magnetic circuit,on which the dynamic characteristic of the HSV,as well as the effects of structural parameters on switching behaviour,are *** on this model,multi-objective optimization is adopted to design an HSV with faster dynamic performance and smaller volume,NSGA-II genetic algorithm is applied to obtain the Pareto front of the desired *** assess the impact before and after optimization,an HSV based on the optimized structure is manufactured and *** experimental results show that the optimized HSV reduces 47.1%of its solenoid volume while improving opening and closing dynamic performance by 14.8%and 43.0%respectively,increasing maximum switching frequency by 6.2%,and expanding flow linear control area by 6.7%.These results validate the optimized structure and indicate that the optimization method provided in the paper is beneficial for developing superior HSV.

关键词： High speed on/off valve Dynamic response Volume Multiobjective optimization NSGA-II genetic algorithm

Regulating the oxidation state of Pd to enhance the selective hydrogenation for 5-hydroxymethylfurfural

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第8期72卷 60-68页

作者： Xin Li Yue Ma xuning Wang Jianguo Wu dong Cao Daojian cheng State Key Laboratory of Organic-Inorganic Composites and College of Chemical Engineering Beijing University of Chemical TechnologyBeijing 100029China

The highly selective hydrogenation of 5-hydroxymethylfurfural to 2,5-dihydroxymethylfuran is an important reaction in the field of biomass hydrogenation,because it is a bridge between biomass resources and chemical ***,we precisely constructed carbon nitride supported Pd-based catalysts by a simple impregnation-reduction *** changing the reduction temperature,catalysts with different oxidation state could be precisely ***,the important correlation between the ratio of Pd^(0)/Pd^(2+)and catalytic activity is revealed during the selective hydrogenation of *** Pd/g—C_(3)N_(4)—300 catalyst with a Pd^(0)/Pd^(2+)ratio of 3/2 showed the highest catalytic activity,which could get 96.9%5-hydroxymethylfurfural conversion and 90.3%2,5-dihydroxymethylfuran *** density functional theory calculation revealed that the synergistic effect between Pd0and Pd2+in Pd/g—C_(3)N_(4)—300 system could boost the adsorption of the substrate and the dissociation of *** this work,we highlight the important correlation between metal oxidation state and catalytic activity,which provides valuable insights for the rational design of precious metal catalysts for hydrogenation reactions.

关键词： Pd/g-C_(3)N_(4) Selective hydrogenation 5-hydroxymethylfurfural 2,5-dihydroxymethylfuran Oxidation state

Ambarzumyan's Theorem for the Dirac Operator on Equilateral Tree Graphs

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2024年第2期40卷 568-576页

作者： dong-Jie WU Xin-Jian xu Chuan-Fu YANG Department of Mathematics School of Mathematics and StatisticsNanjing University of Science and TechnologyNanjing 210094China

The classical Ambarzumyan’s theorem states that if the Neumann eigenvalues of the Sturm-Liouville operator-d^(2)/dx^(2)+q with an integrable real-valued potential q on[0,π] are {n^(2):n≥0},then q=0 for almost all x∈[0,π].In this work,the classical Ambarzumyan’s theorem is extended to the Dirac operator on equilateral tree *** prove that if the spectrum of the Dirac operator on graphs coincides with the unperturbed case,then the potential is identically zero.

关键词： dirac operator quantum graph Ambarzumyan’s theorem inverse spectral problem

Topological non-reciprocal robust waveguide transport

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 39-45页

作者： Ruizhi dong Yihuan Zhu dongxing Mao xu Wang Yong Li Institute of Acoustics Tongji UniversityShanghai 200092China

Devices that surpass the restriction of reciprocity of classical physical waves have brought intriguing possibilities for wave ***-reciprocal acoustic devices that rely on the viscosity of the medium or nonlinear effect have low efficiency and distortion problems respectively,and poor immunity to *** appearance of acoustic topological insulators achieves nonreciprocal transport with high ***,the local nature of topological states means that their appearance depends on a system with a larger *** is,most of the area of a topological device is occupied by useless lattices that do not directly contribute to non-reciprocal *** extra cost of topology protection severely limits the application scenarios of topology states,decreases the cost-effectiveness of topology devices,and is not conducive to device miniaturization and *** this work,we construct an acoustic three-layer heterojunction by introducing two types of domain walls into a conventional quantum Hall effect acoustic topological insulator,and successfully construct a non-reciprocal scattering network that forms topological modes spanning the interlayer *** extended states are still protected by bulk-band topology,making their non-reciprocity robust against *** structure flawlessly realizes the path broadening in a two-dimensional topological system and can accomplish functions such as non-reciprocal acoustic splitting and multichannel *** work opens up opportunities for developing topological-insulator-based non-reciprocal devices in acoustics.

关键词： reciprocal topological topology

Rolling Decision Model of Thermal Power Retrofit and Generation Expansion Planning Considering Carbon Emissions and Power Balance Risk

在线全文

学校读者我要写书评

暂无评论

Energy Engineering 2024年第5期121卷 1309-1328页

作者： dong Pan xu Gui Jiayin xu Yuming Shen Haoran xu Yinghao Ma Economic and Technology Research Institute State Grid Anhui Electric Power Co.Ltd.Hefei230022China School of Electrical and Automation Engineering Hefei University of TechnologyHefei230009China

With the increasing urgency of the carbon emission reduction task,the generation expansion planning process needs to add carbon emission risk constraints,in addition to considering the level of power ***,methods for quantifying and assessing carbon emissions and operational risks are *** results in excessive carbon emissions and frequent load-shedding on some days,although meeting annual carbon emission reduction ***,in response to the above problems,carbon emission and power balance risk assessment indicators and assessment methods,were proposed to quantify electricity abundance and carbon emission risk level of power planning scenarios,considering power supply regulation and renewable energy fluctuation ***,building on traditional two-tier models for low-carbon power planning,including investment decisions and operational simulations,considering carbon emissions and power balance risks in lower-tier operational simulations,a two-tier rolling model for thermal power retrofit and generation expansion planning was *** model includes an investment tier and operation assessment tier and makes year-by-year decisions on the number of thermal power units to be retrofitted and the type and capacity of units to be ***,the rationality and validity of the model were verified through an example analysis,a small-scale power supply system in a certain region is taken as an *** model can significantly reduce the number of days of carbon emissions risk and ensure that the power balance risk is within the safe limit.

关键词： Carbon emission risk power balance risk thermal power retrofit generation expansion planning

A Comparative Study on the Post-Buckling Behavior of Reinforced Thermoplastic Pipes(RTPs)Under External Pressure Considering Progressive Failure

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Ocean Engineering 2024年第2期38卷 233-246页

作者： DING Xin-dong WANG Shu-qing LIU Wen-cheng YE Xiao-han College of Engineering Ocean University of ChinaQingdao 266100China Shandong Provincial Key Laboratory of Ocean Engineering Ocean University of ChinaQingdao 266100China Department of Marine Technology Norwegian University of Science and Technology(NTNU)Trondheim NO-7491Norway

The collapse pressure is a key parameter when RTPs are applied in harsh deep-water *** investigate the collapse of RTPs,numerical simulations and hydrostatic pressure tests are *** the numerical simulations,the eigenvalue analysis and Riks analysis are combined,in which the Hashin failure criterion and fracture energy stiffness degradation model are used to simulate the progressive failure of composites,and the“infinite”boundary conditions are applied to eliminate the boundary *** for the hydrostatic pressure tests,RTP specimens were placed in a hydrostatic chamber after filled with *** has been observed that the cross-section of the middle part collapses when it reaches the maximum *** collapse pressure obtained from the numerical simulations agrees well with that in the ***,the applicability of NASA SP-8007 formula on the collapse pressure prediction was also *** has a relatively greater difference because of the ignorance of the progressive failure of *** the parametric study,it is found that RTPs have much higher first-ply-failure pressure when the winding angles are between 50°and 70°.Besides,the effect of debonding and initial ovality,and the contribution of the liner and coating are also discussed.

关键词： reinforced thermoplastic pipes post-buckling behavior progressive failure of composites debonding initial ovality

Synthesis and characterization of iron clusters with an icosahedral [Fe@Fe12]16+ Core

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第4期11卷 123-129页

作者： Gan xu Yun-Shu Cui xue-Lian Jiang Cong-Qiao xu Jun Li xu-dong Chen Jiangsu Collaborative Innovation Center of Biomedical Functional Materials and Jiangsu Key Laboratory of New Power Batteries School of Chemistry and Materials Science Nanjing Normal University Department of Chemistry and Guangdong Provincial Key Laboratory of Catalytic Chemistry Southern University of Science and Technology Department of Chemistry and Engineering Research Center of Advanced Rare-Earth Materials of Ministry of Education Tsinghua University State Key Laboratory of Coordination Chemistry Nanjing University

Iron-metal clusters are crucial in a variety of critical biological and material systems,including metalloenzymes,catalysts,and magnetic storage ***,a synthetic high-nuclear iron cluster has been absent due to the extreme difficulty in stabilizing species with direct iron-iron *** this work,we have synthesized,crystallized,and characterized a（Tp*）4W4S12(Fe@Fe12) cluster(Tp*=tris（3,5-dimethyl-1-pyrazolyl）borate（1-）),which features a rare trideca-nuclear,icosahedral[Fe@Fe12] cluster core with direct multicenter iron-iron bonding between the interstitial iron（Fei） and peripheral irons（Fep）,as well as Fep…Fepferromagnetic *** chemistry studies reveal that the stability of the cluster arises from the 18-electron shell-closing of the [Fe@Fe12]16+core,assisted by its bonding interactions with the peripheral tridentate [（Tp*）WS3]4-ligands which possess both S→Fe donation and spin-polarized Fe-Wσ *** ground-state electron spin is theoretically predicted to be S=32/2 for the *** existence of low oxidation-state（OS～+1.23） iron in this compound may find interesting applications in magnetic storage,spintronics,redox chemistry,and cluster catalysis.

关键词： Fe13 cluster iron-sulfur cluster low-valence iron iron−iron bond high spin complex

Lycium barbarum glycopeptide(wolfberry extract)slows N-methyl-N-nitrosourea-induced degradation of photoreceptors

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第10期19卷 2290-2298页

作者： Qihang Kong Xiu Han Haiyang cheng Jiayu Liu Huijun Zhang Tangrong dong Jiansu Chen Kwok-Fai So xuesong Mi Ying xu Shibo Tang Department of Ophthalmology Aier Eye HospitalJinan UniversityGuangzhouGuangdong ProvinceChina Department of Ophthalmology The First Affiliated Hospital of Jinan UniversityGuangzhouGuangdong ProvinceChina Guangdong-Hong Kong-Macao Institute of CNS Regeneration Key Laboratory of CNS Regeneration(Ministry of Education)Jinan UniversityGuangzhouGuangdong ProvinceChina Department of Ophthalmology Guangzhou Panyu Central HospitalGuangzhouGuangdong ProvinceChina School of Stomatology Jinan UniversityGuangzhouGuangdong ProvinceChina Aier Academician Station ChangshaHunan ProvinceChina Co-Innovation Center of Neuroregeneration Nantong UniversityNantongJiangsu ProvinceChina State Key Laboratory of Brain and Cognitive Sciences Hong Kong Special Administrative RegionChina

Photoreceptor cell degeneration leads to blindness, for which there is currently no effective treatment. Our previous studies have shown that Lycium barbarum(L. barbarum) polysaccharide(LBP) protects degenerated photoreceptors in rd1, a transgenic mouse model of retinitis pigmentosa. L. barbarum glycopeptide(Lb GP) is an immunoreactive glycoprotein extracted from LBP. In this study, we investigated the potential protective effect of Lb GP on a chemically induced photoreceptor-degenerative mouse model. Wild-type mice received the following: oral administration of Lb GP as a protective pre-treatment on days 1–7;intraperitoneal administration of 40 mg/kg N-methylN-nitrosourea to induce photoreceptor injury on day 7;and continuation of orally administered Lb GP on days 8–14. Treatment with Lb GP increased photoreceptor survival and improved the structure of photoreceptors, retinal photoresponse, and visual behaviors of mice with photoreceptor degeneration. Lb GP was also found to partially inhibit the activation of microglia in N-methyl-N-nitrosourea-injured retinas and significantly decreased the expression of two pro-inflammatory cytokines. In conclusion, Lb GP effectively slowed the rate of photoreceptor degeneration in N-methyl-N-nitrosourea-injured mice, possibly through an anti-inflammatory mechanism, and has potential as a candidate drug for the clinical treatment of photoreceptor degeneration.

关键词： anti-inflammation inherited retinal diseases Lycium barbarum glycopeptide N-methyl-N-nitrosourea opsin photoreceptor reactive gliosis retinal degeneration retinitis pigmentosa rhodopsin

A Pseudo-measurement Modelling Strategy for Active Distribution Networks Considering Uncertainty of DGs

在线全文

学校读者我要写书评

暂无评论

Protection and Control of Modern Power Systems 2024年第5期9卷 1-15页

作者： dongliang xu Junjun xu cheng Qian Zaijun Wu Qinran Hu School of Electrical Engineering Southeast UniversityNanjing 210096China College of Automation&College of Artificial Intelligence Nanjing University of Posts and TelecommunicationsNanjing 210003China

Active distribution networks utilize ad-vanced sensors,communication,and control technologies to achieve flexible and intelligent power distribution *** state estimation(SE)is crucial for distribution management systems to monitor these ***,the scarcity of measurement re-sources has hindered the application of SE technology in distribution *** a dependable pseu-do-measurement model for active distribution networks can significantly enhance the feasibility of *** paper proposes a pseudo-measurement model that aligns with the actual operating status of the distribution network,considering the uncertainty in output from distributed generations(DGs)such as wind turbines and ***,it analyzes and models the uncertainty of high-penetration DG output,establishing a reliable out-put model that incorporates the physical characteristics of wind and photovoltaic ***,it proposes a pseudo-measurement modeling method based on support vector machine(SVM),where the kernel function of the SVM is weighted according to the information entropy of fluctuations in historical operating *** weighting ensures that the established pseudo-measurement model better reflects the actual operating status of the active distribution ***,a mathematical model for optimizing pseudo-measurement selection is developed,with the minimum state estimation error as the objective function and the observability of the active distribution network system as the *** studies demon-strate the accuracy and effectiveness of this *** Terms—Distribution network,pseudo-measure-ment,uncertainty of DGs,state estimation,entropy weighting method-support vector machine(EWM-SVM).

关键词： Distribution network pseudo-measurement uncertainty of DGs state estimation entropy weighting method-support vector machine(EWM-SVM)

0^(--) hidden-heavy tetraquark states via QCD sum rules

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第9期48卷 50-59页

作者： Bing-dong Wan Hong-Tai xu Department of Physics Liaoning Normal UniversityDalian 116029China Center for Theoretical and Experimental High Energy Physics Liaoning Normal UniversityDalian 116029China

In this study,we evaluated the mass spectra of the prospective 0^(--) hidden-charm and hidden-bottom tetraquark states in molecular configuration via QCD sum *** our calculation,the nonperturbative condensate contributions are considered up to dimension eight in operator product *** is found that there could exist 4possible 0^(--) hidden-charm tetraquark states with masses(4.68±0.07),(4.22±0.09),(4.53±0.09),and(4.26±0.13) *** corresponding hidden-bottom partners are found lying at(11.04±0.10),(10.71±0.12),(11.09±0.10),and(11.82±0.14) GeV,*** possible tetraquark decay modes were analyzed,which are expected to be measured in BESⅢ,BELLEⅡ,and LHCb experiments.

关键词： exotic hadronic states QCD sum rules tetraquarks