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Single-electromagnet levitation for density measurement and defect detection

Yuhan JIA, Peng ZHAO, Jun XIE, Xuechun ZHANG, Hongwei ZHOU, Jianzhong FU

《机械工程前沿(英文)》 2021年 第16卷 第1期   页码 186-195 doi: 10.1007/s11465-020-0608-0

摘要: This paper presents a single-electromagnet levitation device to measure the densities and detect the internal defects of antimagnetic materials. The experimental device has an electromagnet in its lower part and a pure iron core in the upper part. When the electromagnet is activated, samples can be levitated stably in a paramagnetic solution. Compared with traditional magnetic levitation devices, the single-electromagnet levitation device is adjustable. Different currents, electromagnet shapes, and distances between the electromagnet and iron core are used in the experiment depending on the type of samples. The magnetic field formed by the electromagnet is strong. When the concentration of the MnCl aqueous solution is 3 mol/L, the measuring range of the single-electromagnet levitation device ranges from 1.301 to 2.308 g/cm . However, with the same concentration of MnCl aqueous solution (3 mol/L), the measuring range of a magnetic levitation device built with permanent magnets is only from 1.15 to 1.50 g/cm . The single-electromagnet levitation device has a large measuring range and can realize accurate density measurement and defect detection of high-density materials, such as glass and aluminum alloy.

关键词: single-electromagnet     electromagnetic levitation     density measurement     defect detection    

Crystallographic orientation effect on cutting-based single atomic layer removal

Wenkun XIE, Fengzhou FANG

《机械工程前沿(英文)》 2020年 第15卷 第4期   页码 631-644 doi: 10.1007/s11465-020-0599-x

摘要: The ever-increasing requirements for the scalable manufacturing of atomic-scale devices emphasize the significance of developing atomic-scale manufacturing technology. The mechanism of a single atomic layer removal in cutting is the key basic theoretical foundation for atomic-scale mechanical cutting. Material anisotropy is among the key decisive factors that could not be neglected in cutting at such a scale. In the present study, the crystallographic orientation effect on the cutting-based single atomic layer removal of monocrystalline copper is investigated by molecular dynamics simulation. When undeformed chip thickness is in the atomic scale, two kinds of single atomic layer removal mechanisms exist in cutting-based single atomic layer removal, namely, dislocation motion and extrusion, due to the differing atomic structures on different crystallographic planes. On close-packed crystallographic plane, the material removal is dominated by the shear stress-driven dislocation motion, whereas on non-close packed crystallographic planes, extrusion-dominated material removal dominates. To obtain an atomic, defect-free processed surface, the cutting needs to be conducted on the close-packed crystallographic planes of monocrystalline copper.

关键词: ACSM     single atomic layer removal mechanism     crystallographic orientation effect     mechanical cutting     Manufacturing III    

Design and analysis of partially decoupled translational parallel mechanisms with single-loop structures

《机械工程前沿(英文)》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0695-1

摘要: This study presents a family of novel translational parallel mechanisms (TPMs) with single-loop topological structures. The proposed mechanism consists of only revolute and prismatic joints. The novel TPMs are simpler in structure and have fewer joints and components than the well-known Delta Robot. Four types of 2-degree of freedom driving systems are applied to different limb structures to avoid the moving actuator that causes the problem of increased moving mass. Four sample TPMs are constructed using the synthesized limbs, and one of them is investigated in terms of kinematic performance. First, a position analysis is performed and validated through numerical simulation to reveal the characteristics of partially decoupled motion, which improves the controllability of TPM. Second, singular configurations are identified, and the resulting singularity curve is obtained. Lastly, the workspace of TPM is analyzed, and the relationship between the singular configurations and the reachable workspace is explored. The workspace of the 3-CRR (C denotes the cylindrical joint and R denotes the revolute joint) translational mechanism is also presented to prove that the proposed TPM has a fairly large workspace.

关键词: translational parallel mechanism     single loop     multiple driving system     workspace analysis     singularity    

Moving policy and regulation forward for single-use plastic alternatives

《环境科学与工程前沿(英文)》 2021年 第15卷 第3期 doi: 10.1007/s11783-021-1423-5

摘要: Single-use plastics are often used once or cannot be reused for extended periods. They are widely consumed with the rapid development of social economy. The waste generated by single-use plastics threatens ecosystem health by entering the environment and ultimately restricts sustainable human development. The innovation of sustainable and environmentally friendly single-use plastic alternative materials and the joint participation of governments, enterprises and the public are promising technologies and management approaches that can solve the problem of single-use plastics wastes. The development of single-use plastic alternative products can be promoted fundamentally only by improving relevant legislation and standards, providing differentiated industrial policies, encouraging scientific and technological innovation and expanding public participation.

关键词: Single-use plastic alternatives     Policy     Regulation     Sustainable development    

Damage propagation and strength prediction of a single-lap interference-fit laminate structure

Peng ZOU, Xiangming CHEN, Hao CHEN, Guanhua XU

《机械工程前沿(英文)》 2020年 第15卷 第4期   页码 558-570 doi: 10.1007/s11465-020-0591-5

摘要: Experimental and finite element research was conducted on the bolted interference fit of a single-lap laminated structure to reveal the damage propagation mechanism and strength change law. A typical single-lap statically loading experiment was performed, and a finite element damage prediction model was built based on intralaminar progress damage theory. The model was programmed with a user subroutine and an interlaminar cohesive zone method. The deformation and damage propagation of the specimen were analyzed, and the failure mechanism of intralaminar and interlaminar damage during loading was discussed. The effect of secondary bending moment on load translation and damage distribution was revealed. The experimental and simulated load–displacement curves were compared to validate the developed model’s reliability, and the ultimate bearing strengths under different fit percentages were predicted. An optimal percentage was also recommended.

关键词: single-lap     interference fit     secondary bending moment     damage mechanism     bearing strength    

Novel casting processes for single-crystal turbine blades of superalloys

Dexin MA

《机械工程前沿(英文)》 2018年 第13卷 第1期   页码 3-16 doi: 10.1007/s11465-018-0475-0

摘要:

This paper presents a brief review of the current casting techniques for single-crystal (SC) blades, as well as an analysis of the solidification process in complex turbine blades. A series of novel casting methods based on the Bridgman process were presented to illustrate the development in the production of SC blades from superalloys. The grain continuator and the heat conductor techniques were developed to remove geometry-related grain defects. In these techniques, the heat barrier that hinders lateral SC growth from the blade airfoil into the extremities of the platform is minimized. The parallel heating and cooling system was developed to achieve symmetric thermal conditions for SC solidification in blade clusters, thus considerably decreasing the negative shadow effect and its related defects in the current Bridgman process. The dipping and heaving technique, in which thin-shell molds are utilized, was developed to enable the establishment of a high temperature gradient for SC growth and the freckle-free solidification of superalloy castings. Moreover, by applying the targeted cooling and heating technique, a novel concept for the three-dimensional and precise control of SC growth, a proper thermal arrangement may be dynamically established for the microscopic control of SC growth in the critical areas of large industrial gas turbine blades.

关键词: superalloy     investment casting     Bridgman process     directional solidification     single crystal     turbine blade    

Numerical analysis of bearing behaviors of single batter piles under horizontal loads in various directions

《结构与土木工程前沿(英文)》 2023年 第17卷 第2期   页码 224-237 doi: 10.1007/s11709-022-0914-1

摘要: The horizontal bearing behavior of a single batter pile (SBP) is vital to its application in practical engineering; however, the horizontal responses of SBPs change with the directions of horizontal loads, and this phenomenon is rarely investigated. Therefore, the directional differences in the horizontal bearing behaviors of SBPs are investigated in this study. Four model tests are conducted to preliminarily examine the effects of the skew angle of horizontal loads on the horizontal bearing capacities and distributions of the bending moments of the SBPs. Subsequently, the differences in the responses of the SBPs under horizontal loads in various directions at full scale are analyzed comprehensively via finite-element (FE) analysis. The effects of the skew angle on SBP-soil interaction are discussed. Moreover, an empirical design method is proposed based on the FE analysis results to predict the bearing ratios of SBPs in medium-dense and dense sand while considering the effects of the skew angle, batter angle, and pile diameter. The method is confirmed to be effective, as confirmed by the close agreement between the predicting results with the model test (reported in this study) and centrifuge model test results (reported in the literature).

关键词: single batter pile     skew horizontal load     model test     finite-element analysis     empirical design method    

Promising approach for preparing metallic single-atom catalysts: electrochemical deposition

《能源前沿(英文)》 2022年 第16卷 第4期   页码 537-541 doi: 10.1007/s11708-022-0837-5

Ionic strength directed self-assembled polyelectrolyte single-bilayer membrane for low-pressure nanofiltration

《化学科学与工程前沿(英文)》 2022年 第16卷 第5期   页码 699-708 doi: 10.1007/s11705-021-2093-3

摘要: Layer-by-layer assembly is a versatile technique for fabricating nanofiltration membranes, where multiple layers of polyelectrolytes are usually required to achieve reasonable separation performance. In this work, an ionic strength directed self-assembly procedure is described for the preparation of nanofiltration membranes consisting of only a single bilayer of poly(diallyldimethylammoniumchloride) and poly(sodium-4-styrenesulfoate). The influence of background ionic strength as well as membrane substrate properties on the formation of single-bilayer membranes are systematically evaluated. Such a simplified polyelectrolyte deposition procedure results in membranes having outstanding separation performance with permeating flux of 14.2 ± 1.5 L∙m–2∙h–1∙bar–1 and Na2SO4 rejection of 97.1% ± 0.8% under a low applied pressure of 1 bar. These results surpass the ones for conventional multilayered polyelectrolyte membranes. This work encompasses an investigation of ionic strength induced coiling of the polyelectrolyte chains and emphasizes the interplay between-polyelectrolyte chain configuration and substrate pore profile. It thus introduces a new concept on the control of membrane fabrication process toward high performance nanofiltration.

关键词: layer-by-layer self-assembly     single bilayer     nanofiltration membrane     desalination    

一种混合电磁气门驱动机构设计 Article

Jawad ASLAM, Xing-hu LI, Faira Kanwal JANJUA

《信息与电子工程前沿(英文)》 2017年 第18卷 第10期   页码 1635-1643 doi: 10.1631/FITEE.1601215

摘要: 提出一种应用于可变气门正时技术无凸轮轴发动机的新型电磁驱动机构。该机构具有轴对称结构,且采用永磁(permanent magnet, PM)和电磁(electro magnet, EM)两种力混合驱动;可提供较大磁动势但保持较低能耗,且改善了瞬态响应,具有较低线圈电感、永磁退磁隔离等优点。仿真和试验结果证实,该机构在平衡位置处可产生约200 N作用力(线圈通电),在电枢底座可以产生500 N作用力(线圈不通电)。对该机构同双电磁阀驱动机构(double solenoid valve actuator,DSVA)进行了比较分析。所提机构和DSVA有限元设计方法经过自主制作的试验样机验证。

关键词: 永磁;电磁;可变气门正时;无凸轮轴发动机;磁动势    

Computer-Aided Design System for CP Single-Screw Compressor

SHEN Jing-feng, YAO Fu-sheng

《机械工程前沿(英文)》 2006年 第1卷 第1期   页码 21-25 doi: 10.1007/s11465-005-0018-3

摘要:

To design various optimum parameters and simulate the working process of CP single-screw compressor, the Computer-Aided Design (CAD) system for the CP single-screw compressor has been established. A new method based on computer graphics technology, database technology, object-oriented programming technology, and visual simulation technology has been adopted in this CAD system. The system has integrated solid modeling function with parameterization design function and animator simulation function based on analyzing the working principle of the CP single-screw compressor. The experimental results show that the CAD system for the CP single-screw compressor is practical and feasible.

关键词: CP single-screw     database technology     simulation technology     programming technology     animator simulation    

The role of single deformed bubble on porous foam tray with submerged orifices on the mass transfer enhancement

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 2127-2143 doi: 10.1007/s11705-023-2363-3

摘要: Foam trays with porous submerged orifices endow bubbles uniformly distributed, which are considered attractive column internals to enhance the gas-liquid mass transfer process. However, its irregular orifice and complex gas-liquid flow make it lack pore-scale investigations concerning the transfer mechanism of dynamic bubbling. In this work, the actual porous structure of the foam tray is obtained based on micro computed tomography technology. The shape, dynamic, and mass transfer of rising bubbles at porous orifices are investigated using the volume of fluid and continue surface force model. The results demonstrate that the liquid encroaching on the gas channels causes the increasing orifices velocity, which makes the trailing bubble easily detach from the midst of the leading bubble and causes pairing coalescence. Additionally, we found that the central breakup regimes significantly improve the gas-liquid interface area and mass transfer efficiency. This discovery exemplifies the mechanism of mass transfer intensification for foam trays and serves to promote its further development.

关键词: bubble formation     porous submerged orifices     process intensification     foam tray    

Evaluation of regenerative braking based on single-pedal control for electric vehicles

Wei LIU, Xintian LIU, Yansong WANG, Hongzhong QI

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 166-179 doi: 10.1007/s11465-019-0546-x

摘要: More than 25% of vehicle kinetic energy can be recycled under urban driving cycles. A single-pedal control strategy for regenerative braking is proposed to further enhance energy efficiency. Acceleration and deceleration are controlled by a single pedal, which alleviates driving intensity and prompts energy recovery. Regenerative braking is theoretically analyzed based on the construction of the single-pedal system, vehicle braking dynamics, and energy conservation law. The single-pedal control strategy is developed by considering daily driving conditions, and a single-pedal simulation model is established. Typical driving cycles are simulated to verify the effectiveness of the single-pedal control strategy. A dynamometer test is conducted to confirm the validity of the simulation model. Results show that using the single-pedal control strategy for electric vehicles can effectively improve the energy recovery rate and extend the driving range under the premise of ensuring safety while braking. The study lays a technical foundation for the optimization of regenerative braking systems and development of single-pedal control systems, which are conducive to the promotion and popularization of electric vehicles.

关键词: electric vehicle     single-pedal control     regenerative braking     co-simulation     dynamometer test    

Single incision laparoscopic cholecystectomy using the one-incision three-trocar technique with all straight

Hongyi Cui

《医学前沿(英文)》 2011年 第5卷 第3期   页码 283-287 doi: 10.1007/s11684-011-0151-9

摘要: Single incision laparoscopic surgery (SILS) is a novel minimally invasive surgical technique that is gaining popularity around the world. One of the most commonly performed procedures is single incision laparoscopic cholecystectomy (SILC). Most reported techniques utilize special purpose-made access port and articulating instruments, rendering the procedure costly and difficult to learn. This article provides a stepwise description of SILC technique using all straight instruments without the need for a special port. It aims to shorten the learning curve for surgeons wishing to adopt a safe and cost-effective SILC technique to their practice.

关键词: laparoscopic cholecystectomy     single incision laparoscopic surgery    

Exhaust hood for steam turbines-single-flow arrangement

Michal HOZNEDL , Ladislav TAJC , Jaroslav KREJCIK , Lukas BEDNAR , Kamil SEDLAK , Jiri LINHART ,

《能源前沿(英文)》 2009年 第3卷 第3期   页码 321-329 doi: 10.1007/s11708-009-0039-4

摘要: In the past, increased attention was given to the development of an optimal shape for the inlet part of LP turbine casings in SKODA POWER. A double-flow design is typically used for high power output turbines. An optimized shape for the internal diffuser has been found, which transforms the kinetic energy of steam into increased pressure, thus effectively increasing the thermodynamic efficiency of the stage. Some conclusions have been drawn from laboratory experiments, others derived directly from on-site measurements at power plants. The conclusions from the development of double-flow turbines form the basis for the design of the single-flow turbine arrangement. Single-flow design is typically used for lower output turbines. There are still some limitations in applying this arrangement. The designer needs to resolve the bearing position and how to ensure access to them. Reinforcing the ribs and supports are used, therefore, to ensure the rigidity of the entire casing. The optimization of the single-flow diffuser shape is therefore the subject of the study presented below.

关键词: exhaust hood     steam turbines     single-flow arrangement    

标题 作者 时间 类型 操作

Single-electromagnet levitation for density measurement and defect detection

Yuhan JIA, Peng ZHAO, Jun XIE, Xuechun ZHANG, Hongwei ZHOU, Jianzhong FU

期刊论文

Crystallographic orientation effect on cutting-based single atomic layer removal

Wenkun XIE, Fengzhou FANG

期刊论文

Design and analysis of partially decoupled translational parallel mechanisms with single-loop structures

期刊论文

Moving policy and regulation forward for single-use plastic alternatives

期刊论文

Damage propagation and strength prediction of a single-lap interference-fit laminate structure

Peng ZOU, Xiangming CHEN, Hao CHEN, Guanhua XU

期刊论文

Novel casting processes for single-crystal turbine blades of superalloys

Dexin MA

期刊论文

Numerical analysis of bearing behaviors of single batter piles under horizontal loads in various directions

期刊论文

Promising approach for preparing metallic single-atom catalysts: electrochemical deposition

期刊论文

Ionic strength directed self-assembled polyelectrolyte single-bilayer membrane for low-pressure nanofiltration

期刊论文

一种混合电磁气门驱动机构设计

Jawad ASLAM, Xing-hu LI, Faira Kanwal JANJUA

期刊论文

Computer-Aided Design System for CP Single-Screw Compressor

SHEN Jing-feng, YAO Fu-sheng

期刊论文

The role of single deformed bubble on porous foam tray with submerged orifices on the mass transfer enhancement

期刊论文

Evaluation of regenerative braking based on single-pedal control for electric vehicles

Wei LIU, Xintian LIU, Yansong WANG, Hongzhong QI

期刊论文

Single incision laparoscopic cholecystectomy using the one-incision three-trocar technique with all straight

Hongyi Cui

期刊论文

Exhaust hood for steam turbines-single-flow arrangement

Michal HOZNEDL , Ladislav TAJC , Jaroslav KREJCIK , Lukas BEDNAR , Kamil SEDLAK , Jiri LINHART ,

期刊论文