检索结果-南通市图书馆

质谱离子源内裂解和重排可能会为化学反应中间体的捕获带来错误信息

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

质谱学报 2024年第1期45卷 111-122,I0004页

作者：赵玲玲梁驰予汪杰张新星南开大学化学学院天津300071

质谱法广泛应用于在线反应监测和高活性中间体捕获,极大助力了化学反应机理研究。微液滴具有极端的化学环境,有望捕获高活性中间体,与质谱联用可实现原位表征。有报道表明,微液滴表面的局部强酸环境可以稳定短寿命的碳正离子,结合在线... 详细信息

质谱法广泛应用于在线反应监测和高活性中间体捕获,极大助力了化学反应机理研究。微液滴具有极端的化学环境,有望捕获高活性中间体,与质谱联用可实现原位表征。有报道表明,微液滴表面的局部强酸环境可以稳定短寿命的碳正离子,结合在线质谱可以检测其信号。本文使用电喷雾电离质谱(ESI-MS)测定了一系列碳正离子的前体分子,在排除微液滴效应影响的前提下,检测到这些碳正离子信号。进一步的实验表明,受进样毛细管高温和管透镜电压的共同影响,在质谱的粗真空区域,前体物种会发生源内裂解产生碳正离子碎片,这些碎片可能会被误判为液滴反应中产生的高活性中间体,从而影响反应机理研究。本工作表明,在使用质谱进行反应监测和中间体捕获研究时,应谨慎地考察各仪器参数,尤其是离子光学系统所加电压对离子的影响,以避免对化学反应机制的误判。

关键词：电喷雾电离质谱(ESI-MS) 碳正离子源内裂解

优秀民族文化融入民族地区儿童价值观教育的逻辑进路

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

民族教育研究 2024年第3期35卷 145-151页

作者：杨茂庆苏天一周驰亮广西师范大学教育学部广西桂林541004 广西师范大学职业技术师范学院广西桂林541004

优秀民族文化融入民族地区儿童价值观教育遵循必要的逻辑进路,其逻辑起点是以铸牢中华民族共同体意识为根本目标,以弘扬社会主义核心价值观为本质要求,以准确把握中华文化与各民族优秀文化关系为关键基点,促进民族地区儿童形成价值共识... 详细信息

优秀民族文化融入民族地区儿童价值观教育遵循必要的逻辑进路,其逻辑起点是以铸牢中华民族共同体意识为根本目标,以弘扬社会主义核心价值观为本质要求,以准确把握中华文化与各民族优秀文化关系为关键基点,促进民族地区儿童形成价值共识。优秀民族文化贯穿于民族地区儿童的日常生活,其价值逻辑体现为传承文化基因,推进以文化人;挖掘文化价值,深化以文育人;促进文化共生,实现以文成人。基于此,深化教育主体的优秀民族文化认知,科学挖掘优秀民族文化资源,构建家校社“三位一体”的教育体系是优秀民族文化融入民族地区儿童价值观教育的应然选择。

关键词：社会主义核心价值观铸牢中华民族共同体意识优秀民族文化民族地区儿童价值观教育

Particle fracture and debonding during orthogonal machining of metal matrix composites

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

Advances in Manufacturing 2017年第1期5卷 77-82页

作者： A. Pramanik liang-chi Zhang Department of Mechanical Engineering Curtin UniversityBentley WA 6102 Australia School of Mechanical and Manufacturing Engineering University of New South Wales Sydney NSW 2052Australia

This paper investigates the particle fracture and debonding during machining of metal matrix composite （MMC） due to developed stress and strain, and interaction with moving tool by finite element analysis. The machining zone was divided into three regions： primary, secondary and tertiary deformation zones. The tendency of particles to fracture in each deformation zone was investigated. The findings of this study were also discussed with respect to the experimental results available in the literature. It was found that particles at the cutting path inthe tertiary deformation zone fractured as it interacted with tool. In the secondary deformation zone, particles interacted with other particles as well as cutting tool. This caused debonding and fracture of huge number of particles as those were moving up along the rake face with the chips. No particle fracture was noted at the primary deformation zone. The results obtained from finite element analysis were very similar to those obtained from experimental studies.

关键词： Particle reinforced metal matrix composite Particle fracture Particle debonding Finite elementanalysis Strain distribution

Understanding the formation mechanism of subsurface damage in potassium dihydrogen phosphate crystals during ultraprecision fly cutting

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Manufacturing 2019年第3期7卷 270-277页

作者： Yong Zhang Ning Hou liang-chi Zhang School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001People's Republic of China School of Mechatronics Engineering Shenyang Aerospace UniversityShenyang 110136People's Republic of China Laboratory for Precision and Nano Processing Technologies School of Mechanical and Manufacturing EngineeringThe University of New South WalesSydneyNSW 2052Australia

Potassium dihydrogen phosphate(KDP)crystals play an important role in high-energy laser systems,but the laser damage threshold(LDT)of KDP components is lower than *** LDT is significantly influenced by subsurface damage produced in KDP ***,it is very challenging to detect the subsurface damage caused by processing because a KDP is soft,brittle,and sensitive to the external environment(e.g.,humidity,temperature and applied stress).Conventional characterization methods such as transmission electron microscopy are ineffective for this *** paper proposes a nondestructive detection method called grazing incidence X-ray diffraction(GIXD)to investigate the formation of subsurface damage during ultra-precision fly cutting of KDP *** crystal planes,namely(200),(112),(312),(211),(220),(202),(301),(213),(310)and(303),were detected in the processed subsurface with the aid of GIXD,which provided very different results for KDP crystal *** results mean that single KDP crystals change into a lattice misalignment structure(LMS)due to mechanical stress in the *** crystal planes match the slip systems of the KDP crystals,implying that dislocations nucleate and propagate along slip systems to result in the formation of the LMS under shear and compression *** discovery of the LMS in the subsurface provides a new insight into the nature of the laser-induced damage of KDP crystals.

关键词： Potassium dihydrogen phosphate(KDP)crystals Subsurface damage Lattice misalignment structure Slip systems

大跨度变截面钢箱梁托管桥安全监测设计与成果分析

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

水利科技与经济 2024年第5期30卷 40-45页

作者：梁迟郝永志新疆水利水电勘测设计研究院有限责任公司乌鲁木齐830000

针对目前国内单跨跨度最大的变截面连续钢箱梁桥面上铺设的输水管道直径最大的托管桥桥体应力应变、竖向挠度以及桥上输水管道应力应变监测成果进行分析。结果表明,钢箱梁上下表面的钢板应力均与环境温度呈负相关,与过水荷载大小呈正相... 详细信息

针对目前国内单跨跨度最大的变截面连续钢箱梁桥面上铺设的输水管道直径最大的托管桥桥体应力应变、竖向挠度以及桥上输水管道应力应变监测成果进行分析。结果表明,钢箱梁上下表面的钢板应力均与环境温度呈负相关,与过水荷载大小呈正相关;桥体竖向挠度与过水荷载呈正相关,运行期变形量较首次通水时小;输水管道钢板应力分布上基本呈底部最大、左右管腰次之、顶部最小。

关键词：大跨度钢箱梁托管桥安全监测成果分析

Ultrasonic vibration-assisted machining:principle,design and application

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

Advances in Manufacturing 2015年第3期3卷 173-192页

作者： Wei-Xing Xu liang-chi Zhang Laboratory for Precision and Nano Processing Technologies School of Mechanical and Manufacturing EngineeringThe University of New South Wales

Ultrasonic vibration-assisted （UVA） machining is a process which makes use of a micro-scale high frequency vibration applied to a cutting tool to improve the material removal effectiveness. Its principle is to make the tool-workpiece interaction a microscopically non-monotonic process to facilitate chip separation and to reduce machining forces. It can also reduce the deformation zone in a workpiece under machining, thereby improving the surface integrity of a component machined. There are several types of UVA machining processes, differentiated by the directions of the vibrations introduced relative to the cutting direction. Applications of UVA machining to a wide range of workpiece materials have shown that the process can considerably improve machining performance. This paper aims to provide a comprehensive discussion and review about some key aspects of UVA machining such as cutting kinematics and dynamics, effect of workpiece materials and wear of cutting tools, involving a wide range of workpiece materials including metal alloys, ceramics, amorphous and composite materials. Some aspects for further investigation are also outlined at the end.

关键词： Ultrasonic vibration-assisted (UVA) machining. Cutting Metal alloys Ceramics Composites

Nano-machining of materials： understanding the process through molecular dynamics simulation

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

Advances in Manufacturing 2017年第1期5卷 20-34页

作者： Dan-Dan Cui liang-chi Zhang Laboratory for Precision and Nano Processing TechnologiesSchool of Mechanical and Manufacturing Engineering TheUniversity of New South Wales Sydney NSW 2052Australia

Molecular dynamics （MD） simulation has been widely applied in various complex, dynamic processes at atomistic scale, because an MD simulation can provide some deformation details of materials in nano-processing and thus help to investigate the critical and important issues which cannot be fully revealed by experiments. Extensive research with the aid of MD simulation has provided insights for the development of nanotechnology. This paper reviews the fundamentals of nano-machining from the aspect of material structural effects, such as single crystalline, polycrystalline and amorphous materials. The classic MD simulations of nano-indentation and nano-cutting which have aimed to investigate the machining mechanism are discussed with respect to the effects of tool geometry, material properties and machining parameters. On nano-milling, the discussion focuses on the understanding of the grooving quality in relation to milling conditions.

关键词： Molecular dynamics Nano-milling Nano-indentation Nano-cutting Groove quality Multi-grooving

Elastic-plastic-brittle transitions of potassium dihydrogen phosphate crystals:characterization by nanoindentation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Manufacturing 2020年第4期8卷 447-456页

作者： Yong Zhang Ning Hou liang-chi Zhang Qi Wang School of Mechatronics Engineering Harbin Institute of TechnologyHarbin 150001People's Republic of China School of Mechatronics Engineering Shenyang Aerospace UniversityShenyang 110136.People's Republic of China Laboratory for Precision and Nano Processing Technologies School of Mechanical and Manufacturing EngineeringThe University of New South WalesSydneyNSW 2052Australia

Potassium dihydrogen phosphate(KDP)crystals are widely used in laser ignition facilities as optical switching and frequency conversion *** crystals are soft,brittle,and sensitive to external conditions(e.g.,humidity,temperature,and applied stress).Hence,conventional characterization methods,such as transmission electron microscopy,cannot be used to study the mechanisms of material ***,understanding the mechanism of plastic-brittle transition in KDP crystals is important to prevent the fracture damage during the machining *** study explores the plastic deformation and brittle fracture mechanisms of KDP crystals through nanoindentation experiments and theoretical *** results show that dislocation nucleation and propagation are the main mechanisms of plastic deformation in KDP crystals,and dislocation pileup leads to brittle fracture during *** experiments using various indenters indicate that the external stress fields influence the plastic deformation of KDP crystals,and plastic deformation and brittle fracture are related to the material's ***,the E l Ning Hou 13b908074@*** liang-chi Zhang ***@*** 1 School of Mechatronics Engineering,Harbin Institute of Technology,Harbin 150001,People's Republic of china 2 School of Mechatronics Engineering,Shenyang Aerospace University,Shenyang ***'s Republic of china'Laboratory for Precision and Nano Processing Technologies,School of Mechanical and Manufacturing Engineering,The University of New South Wales,Sydney,NSW 2052,Australia effect of loading rate on the KDP crystal deformation is practically *** results of this research provide important information on reducing machining-induced damage and further improving the optical performance of KDP crystal components.

关键词： Potassium dihydrogen phosphate(KDP)crystal Transition mechanism Plastic deformation Brittle fracture

Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Manufacturing 2018年第4期6卷 376-383页

作者： Yong Zhang Ning Hou liang-chi Zhang School of Mechatronics Engineering The Harbin Institute of Technology Harbin 150001 People's Republic of China Ministry of Education Key Laboratory of Micro-systems and Micro-structures Manufacturing The Harbin Institute of Technology Harbin 150001 People's Republic of China Laboratory for Precision and Nano Processing Tech no logies. School of Mechanical and Manufacturing Engineering The University of New South Wales Sydney NSW 2052 Australia

It has been a tremendous challenge to manu facture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the require ments of high-energy laser systems. The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP. This study investigates the room tem perature creep-deformation of KDP crystals with the aid of nanoindentation. A stress analysis was carried out to identify the creep mechanism. The results showed that KDP crystals could be plastically deformed at the nanoscale. Dislocation motion is responsible for creep-deformation. Both creep rate and creep depth decrease with decrease in peak force and loading rate. Dislocation nucleation and propagation bring about pop-ins in the load displacement curves during nanoindentation.

关键词： Potassium dihydrogen phosphate (KDP) crystals Creep-deformation Stress Dislocation