检索结果-南通市图书馆

Microstructure evolution,mechanical properties and fracture behavior of Al-xSi/AZ91d bimetallic composites prepared by a compound casting

引用

Journal of Magnesium and Alloys 2024年第5期12卷 1944-1964页

作者： guangyu Li Wenming Jiang feng guan Junwen Zhu Yang Yu Zitian Fan State Key Laboratory of Materials Processing and die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

In this paper,the effect of the Si content on microstructure evolution,mechanical properties,and fracture behavior of the Al-xSi/AZ91d bimetallic composites prepared by compound casting was investigated *** obtained results showed that all the Al-xSi/AZ91d bimetallic composites had a metallurgical reaction layer(MRL),whose thickness increased with increasing Si content for the hypoeutectic Al-Si/AZ91d composites,while the hypereutectic Al-Si/AZ91d composites were *** MRL included eutectic layer(E layer),intermetallic compound layer(IMC layer)and transition region layer(T layer).In the IMC layer,the hypereutectic Al-Si/AZ91d composites contained some Si solid solution and flocculent Mg_(2)Si+Al-Mg IMCs phases not presented in the hypoeutectic Al-Si/AZ91d ***,increasing Si content,the thickness proportion of the T layer increased,forming an inconsistent preferred orientation of the *** shear strengths of the Al-xSi/AZ91d bimetallic composites enhanced with increasing Si content,and the Al-15Si/AZ91d composite obtained a maximum shear strength of 58.6 MPa,which was 73.4% higher than the Al-6Si/AZ91d *** fractures of the Al-xSi/AZ91d bimetallic composites transformed from the T layer into the E layer with the increase of the Si *** improvement of the shear strength of the Al-xSi/AZ91d bimetallic composites was attributed to the synergistic action of the Mg_(2)Si particle reinforcement,the reduction of oxidizing inclusions and the ratio of Al-Mg IMCs as well as the orientation change of the MRL.

关键词： Al/Mg bimetallic composites Si content Mg_(2)Si reinforcement Microstructure Mechanical properties Fracture behavior

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

dimensional reduction enhances photocatalytic carbon dioxide reduction performance of metal-organic frameworks

引用

Nano Research 2024年第5期17卷 3653-3659页

作者： Kaiyue Ma Jixin Li Jinlu Liu Chunguang Li Zhan Shi Shouhua feng State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of ChemistryJilin UniversityChangchun 130012China

Metal-organic frameworks(MOFs)have shown significant potential as *** has been widely assumed that all catalytic active sites within MOFs are functional in photocatalytic reactions but for a three-dimensional MOF,whether the internal catalytic active sites can effectively absorb light and actively contribute to photocatalytic reactions remains to be *** this context,we synthesized a two-dimensional nanosheet MOF(2d-MOF)and a three-dimensional bulk MOF(3d-MOF)composed of Zr^(6) clusters and tetracarboxylic porphyrin(TCPP)by the approach described in the ***(bpy)(CO)^(3)Cl(bpy=2,2’-bipyridine),which has remarkable CO_(2) photoreduction ability,was introduced to the two MOFs to create two new photocatalysts 2d-MOF-Re and 3d-MOF-Re,*** CO_(2) reduction experiments show that based on the equal number of catalytic active sites,the CO turnover number(TON)of 2d-MOF-Re reaches 27.8 in 6 h,which is 50 times that of *** result shows that certain catalytic active sites inside the bulk MOF are inactive due to the inability to absorb *** study illuminates the potential of the dimensional reduction approach in the design of photocatalysts to exploit the capabilities fully.

关键词： photocatalysis CO_(2)reduction metal-organic frameworks(MOFs) nanosheets light absorption

来源：

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

A fast and high-accurate commutation failure identification method for LCC-HVdC system

引用

HIgH VOLTAgE 2024年第3期9卷 721-732页

作者： feng, Jing Liu, Zhijie Li, Kejun Li, Bingkun Li, Jiachen Li, Liangzi Shandong Univ Sch Elect Engn Jinan Shandong Peoples R China

Commutation failure (CF) is one of the most common issues in line-commuted converter-based high voltage direct current systems (LCC-HVdC), leading to critical power system security and stability problems. Accurate and rapid identification of CF is crucial to prevent subsequent CF in HVdC systems. However, the existing CF identification methods are lack of the required accuracy and speed. The relationship between bridge arm current, commutation voltage, and trigger pulse based on the commutation progress mechanism after the AC fault is analysed in this paper. A novel CF identification method is presented, which utilises the CF identification factor, enabling fast and high-accurate identification without relying on the value of the extinction angle. The proposed method offers a simpler and more efficient implementation in engineering practice. Finally, the effectiveness of the proposed method is verified in both the standard International Council on Large Electric systems HVdC model and the Hardware in Loop test using practical project parameters. The results demonstrate that the proposed method can accurately and fast identify CF.

关键词： STABILITY ANALYSIS VOLTAgE STRATEgY

来源：

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

Subnanometric bimetallic Pt-Pd clusters in zeolites for efficient hydrogen production and selective tandem hydrogenation of nitroarenes

引用

Science China Chemistry 2024年第9期67卷 2911-2917页

作者： Jiafu Li Tao Cai Yanran feng Xia Liu Ning Wang Qiming Sun Institute of Sustainable Energy and Resources College of Chemistry and Chemical EngineeringKey Laboratory of Shandong Provincial Universities for Functional Molecules and MaterialsQingdao UniversityQingdao 266071China Innovation Center for Chemical Sciences College of ChemistryChemical Engineering and Materials ScienceJiangsu Key Laboratory of Advanced Negative Carbon TechnologiesSoochow UniversitySuzhou 215123China

The solvolysis of ammonia borane(AB)and the hydrogenation of nitroarenes represent significant reactions for hydrogen generation and value-added chemical *** strategic engineering of the catalysts is imperative for surmounting obstacles associated with their stability and catalytic *** this work,subnanometric bimetallic Pt–Pd clusters were encapsulated within silicalite-1(S-1)zeolites through a ligand-protected in-situ hydrothermal synthesis *** synergetic effect of bimetallic composition and zeolite confinement markedly enhances the catalytic performance of representative Pt_(0.5)Pd_(0.5)@S-1-H catalyst,affording exceptional turnover frequency(TOF)values of 1,043 and 573 mol_(H_(2))mol_(metal)^(-1)min^(-1)for AB hydrolysis and methanolysis at ambient conditions,respectively,surpassing most of the state-of-the-art Pt-based *** and isotopic experiments reveal that the bimetallic catalytic system remarkably boosts the O-H cleavage of water,thereby facilitating the H_(2) production from AB ***,a conspicuous synergistic effect is demonstrated in the shape-selective tandem hydrogenation of nitroarenes,with the bimetallic catalyst facilitating both AB hydrolysis and nitroarene hydrogenation,giving a high TOF value of 1,260 h^(-1)under atmospheric *** study not only demonstrates the effectiveness of bimetallic nanocatalysts encapsulated in zeolites for hydrogen production from chemical hydrogen storage materials,but also paves the way for the design of catalysts with multifunctional active sites capable of synergistically promoting tandem catalytic processes.

关键词： subnanometer bimetallic cluster zeolite synergistic effect ammonia borane solvolysis selective tandem hydrogenation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Preparation of Chemically Recyclable Poly(ether-alt-ester) by the Ring Opening Polymerization of Cyclic Monomers Synthesized by Coupling glycolide and Epoxides

引用

Chinese Journal of Polymer Science 2024年第2期42卷 168-175,I0006页

作者： feng Ren Zhuang-Zhuang Liang Ming-Xin Niu Chen-Yang Hu Xuan Pang Key Laboratory of Polymer Ecomaterials Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei230026China

Polyester and polyether are two key oxygenated polymers, and completely alternative sequence of poly(ester-alt-ether) could efficiently combine the advantages(including flexibility, degradability, etc.) of both segments. Currently, despite their copolymers could be synthesized from one-pot mixture of cyclic esters and epoxides, perfectly alternative microstructure is very challenging to realize and typically restricted to certain monomer pairs. Moving forward, synthesizing poly(ester-alt-ether) from commercially available and largescale monomers would be a significant advance. For example, successfully commercialized poly(glycolic acid)(PgA), which is not easily soluble in polymers due to its high crystallinity and is brittle and difficult to control the degradation cycle, would encounter a new paradigm if engineered into poly(ester-altether). In this work, starting from the design of monomer with hybrid structures, we successfully synthesized a series of 1,4-dioxan-2-one containing different substituents based on glycolide(gA) and epoxides using commercially available Salen-Cr(III) and PPNCl catalytic *** new monomers underwent ring-opening polymerization(ROP) to form a series of poly(ester-alt-ether) with perfectly alternating glycolic acid and propylene glycol repeat units under catalytic system of thiourea/base. The poly(ester-alt-ether) have significantly lower glass-transition temperature than PgA. Additionally, the poly(ester-alt-ether) can be chemically recovered to monomer using Sn(Oct)2 or 1,8-diazabicyclo[5.4.0]undecane-7-ene(dBU) as a catalyst in solution, thus establishing a closed-loop life cycle. From monomers derived from gA and epoxides, this work furnishes a novel strategy for the synthesis of poly(ester-alt-ether) with chemical recyclability.

关键词： Polyester Polyether Alternative copolymer Ring-opening polymerization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Pure quantum gradient descent algorithm and full quantum variational eigensolver

引用

Frontiers of physics 2024年第2期19卷 221-234页

作者： Ronghang Chen Zhou guang Cong guo guanru feng Shi-Yao Hou College of Physics and Electronic Engineering Center for Computational SciencesSichuan Normal UniversityChengdu 610068China Shenzhen SpinQ Technology Co. Ltd.Shenzhen 518045China dEEPROUTE.AI

Optimization problems are prevalent in various fields,and the gradient-based gradient descent algorithm is a widely adopted optimization ***,in classical computing,computing the numerical gradient for a function with variables necessitates at least d+1 function evaluations,resulting in a computational complexity of O(d).As the number of variables increases,the classical gradient estimation methods require substantial resources,ultimately surpassing the capabilities of classical ***,leveraging the principles of superposition and entanglement in quantum mechanics,quantum computers can achieve genuine parallel computing,leading to exponential acceleration over classical algorithms in some *** this paper,we propose a novel quantum-based gradient calculation method that requires only a single oracle calculation to obtain the numerical gradient result for a multivariate *** complexity of this algorithm is just O(1).Building upon this approach,we successfully implemented the quantum gradient descent algorithm and applied it to the variational quantum eigensolver(VQE),creating a pure quantum variational optimization *** with classical gradient-based optimization algorithm,this quantum optimization algorithm has remarkable complexity advantages,providing an efficient solution to optimization *** proposed quantum-based method shows promise in enhancing the performance of optimization algorithms,highlighting the potential of quantum computing in this field.

关键词： quantum algorithm gradient descent variational quantum algorithm

来源：

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

On the Performances of Estimating Stellar Atmospheric Parameters from CSST Broad-band Photometry

引用

Research in Astronomy and Astrophysics 2024年第4期24卷 161-173页

作者： Rui-feng Shi Yang Huang Xin-Yi Li Hua-Wei Zhang School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China South-Western Institute for Astronomy Research Yunnan UniversityKunming 650500China CAS Key Lab of Optical Astronomy Key Laboratory of Space Astronomy and TechnologyNational Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China College of Physics and Electronic Engineering Qilu Normal UniversityJinan 250200China department of Astronomy School of PhysicsPeking UniversityBeijing 100871China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

deriving atmospheric parameters of a large sample of stars is of vital importance to understand the formation and evolution of the Milky *** surveys,especially those with near-ultraviolet filters,can offer accurate measurements of stellar parameters,with the precision comparable to that from low/medium resolution *** this study,we explore the capability of measuring stellar atmospheric parameters from Chinese Space Station Telescope(CSST)broad-band photometry(particularly in the near-ultraviolet bands),based on synthetic colors derived from model *** find that colors from the optical and near-ultraviolet filter systems adopted by CSST show significant sensitivities to the stellar atmospheric parameters,especially the *** to our mock data tests,the precision of the photometric metallicity is quite high,with typical values of0.17 and 0.20 dex for dwarf and giant stars,*** precision of the effective temperature estimated from broad-band colors are within 50 K.

关键词： methods:data analysis stars:abundances surveys

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Regulated polarization degree of upconversion luminescence and multiple anti-counterfeit applications

引用

Rare Metals 2024年第5期43卷 2172-2183页

作者： dong-Ping Wen Ping Chen Yi Liang Xiao-Ming Mo Cao-feng Pan Center On Nanoenergy Research Guangxi Key Laboratory for Relativistic AstrophysicsSchool of Physical Science and TechnologyGuangxi UniversityNanning 530004China Key Laboratory of Micronano Energy and Sensor CAS Center for Excellence in NanoscienceBeijing Institute of Nanoenergy and NanosystemsChinese Academy of SciencesBeijing 100140China

Polarization upconversion luminescence(PUCL)of lanthanide ions(Ln^(3+))has been widely used in single particle tracking,microfluidics detection,three-dimensional displays,and so ***,no effective strategy has been developed for modulating *** we report a strategy to regulate PUCL in Ho^(3+)-doped NaYF4single nanorods based on the number of upconversion *** constructing a multiphoton upconversion system for Ho^(3+),we regulate the degree of polarization(dOP)of PUCL from 0.590 for two-photon luminescence to 0.929 for three-photon upconversion luminescence(UCL).Furthermore,our strategy is verified from cross-relaxation between Ho^(3+)and Yb^(3+),excitation wavelength,excitation power density,and local site *** this regulation strategy of PUCL has also been achieved in Tm^(3+),with the dOP ranging from 0.233 for two-photon luminescence to 0.925 for four-photon UCL Besides,multi-dimensional anti-counterfeiting display has been explored with *** work provides an effective strategy for regulating PUCL and also provides more opportunities for the development of polarization display optical encoding,anti-counterfeiting,and integrated optical devices.

关键词： Polarization upconversion luminescence degree of polarization Population density of excited state Number of upconversion photons Polarization anti-counterfeitingdisplay

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Supermassive black holes triggered by QCd axion bubbles

引用

Communications in Theoretical Physics 2024年第5期76卷 134-139页

作者： Hai-Jun Li Ying-Quan Peng Wei Chao Yu-feng Zhou Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Center for Advanced Quantum Studies Department of PhysicsBeijing Normal UniversityBeijing 100875China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China International Centre for Theoretical Physics Asia-Pacific Beijing/HangzhouChina

Supermassive black holes(SMBHs)are ubiquitous in the center of galaxies,although the origin of their massive seeds is still *** this paper,we investigate the formation of SMBHs from the quantum chromodynamics(QCd)axion *** this case,primordial black holes(PBHs)are considered as the seeds of SMBHs,which are generated from the QCd axion bubbles due to an explicit Peccei–Quinn(PQ)symmetry breaking after *** QCd axion bubbles are formed when the QCd axion starts to oscillate during the QCd phase *** consider a general case in which the axion bubbles are formed with the bubble effective angle θ_(eff)∈(0,π],leading to the minimum PBH mass∼■(10^(4)−10^(7))M⊙for the axion decay constant f_(a)∼■(10^(16))*** PBHs at this mass region may account for the seeds of SMBHs.

关键词： supermassive black holes primordial black holes quantum chromodynamics axion

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Multimorbidity and mortality among older patients with coronary heart disease in Shenzhen,China

引用

Journal of geriatric Cardiology 2024年第1期21卷 81-89页

作者： Fu-Rong LI Shuang WANg Xia LI Zhi-Yuan CHENg Cheng JIN Chun-Bao MO Jing ZHENg feng-Chao LIANg dong-feng gU Shenzhen Key Laboratory of Cardiovascular Health and Precision Medicine Southern University of Science and TechnologyShenzhenGuangdongChina School of Public Health and Emergency Management Southern University of Science and TechnologyShenzhenGuangdongChina Shenzhen Health development Research and data Management Center ShenzhenChina School of Medicine Southern University of Science and TechnologyShenzhenGuangdongChina

BACKgROUNd The current understanding of the magnitude and consequences of multimorbidity in Chinese older adults with coronary heart disease(CHd)is *** aimed to assess the association and population-attributable fractions(PAFs)between multimorbidity and mortality among hospitalized older patients who were diagnosed with CHd in Shenzhen,*** We conducted a retrospective cohort study of older Chinese patients(aged≥65 years)who were diagnosed with *** proportional hazards models were used to estimate the associations between multimorbidity and all-cause and cardiovascular disease(CVd)*** also calculated the *** The study comprised 76,455 older hospitalized patients who were diagnosed with CHd between January 1,2016,and August 31,*** them,70,217(91.9%)had multimorbidity,defined as the presence of at least one of the predefined 14 chronic *** with cancer,hemorrhagic stroke and chronic liver disease had the worst overall death risk,with adjusted HRs(95%CIs)of 4.05(3.77,4.38),2.22(1.94,2.53),and 1.85(1.63,2.11),*** CVd mortality,the highest risk was observed for hemorrhagic stroke,ischemic stroke,and chronic kidney disease;the corresponding adjusted HRs(95%CIs)were 3.24(2.77,3.79),1.91(1.79,2.04),and 1.81(1.64,1.99),***-cause mortality was mostly attributable to cancer,heart failure and ischemic stroke,with PAFs of 11.8,10.2,and 9.1,*** for CVd mortality,the leading PAFs were heart failure,ischemic stroke and diabetes;the corresponding PAFs were 18.0,15.7,and 6.1,*** Multimorbidity was common and had a significant impact on mortality among older patients with CHd in Shenzhen,***,heart failure,ischemic stroke and diabetes are the primary contributors to ***,prioritizing improved treatment and management of these comorbidities is essential for the survival prognosis of CHd patients from a holistic public health perspective.

关键词： patients morbidity mortality

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：