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International Bhurban Conference on Applied sciences & Technology, IBCAST

作者： Zhaib Muneer Ahmed Muhammad Ali Nasir Zafar Iqbal Muhammad Talha Aamir Dept. of Mechanical Engineering University of Engineering & Technology (UET) Taxila Pakistan Dept. of Surface & Materials Engineering (SCME) National University of Science & Technology (NUST) Islamabad Pakistan

ISBN: (数字)9798350308259

ISBN: (纸本)9798350308266

Today, Sandwich composite radomes are being used in fighter aircrafts, drones, UAV's and missiles. Generally radome structure can be monolayer, two layer, three layer (A-Type) and five layer (C-Type). For current study, a multidisciplinary design process for manufacturing hybrid sandwich composite A-type radomes is presented. The methodology is composed of two parallel setups for testing of electromagnetic behavior and mechanical properties of selected materials, which are simultaneously essential for the better performance of radome. The design process begins with the choice of an appropriate material to satisfy the service requirements, such as EMI transparency and structural integrity against aerodynamic loads. To choose the appropriate material and core foam, the Multi Criteria Decision Making (MCDM) method was also used. The MCDM assigns ranking to the materials to be chosen in order to satisfy functional requirements. Accordingly full scale nose radome of a flight vehicle (<0.8 Mach) was manufactured utilizing hand-layup technique assisted by vacuum bagging using SGlass/PMI Foam/Kevl $a$ and low viscosity epoxy. The full scale radome was tested to check EMI behavior (X-band frequencies) by free space measurement method. EMI response was found satisfying the requirements (as per MIL R-7705B) Furthermore, to ensure that selected materials and layup sequence will fulfil structural performance requirements of Radome, multiple specimens were prepared adhering same stacking sequence as that of the Radome. mechanical testing of specimens was carried out in accordance of ASTM Standard for flexure and tensile testing (ASTM D7246/D760 and ASTM D3039, respectively). Tensile strength of S-Glass and Kevlar was found 263 MPa and 335 MPa respectively, and flexural strength was 351 MPa and 336 MPa, respectively. The flexural testing was also done of sandwich samples comprises, as per ASTM D7246, of S-glass / Foam / Kevlar in accordance 3x ply/4mm/3x ply and 200 gsm in weig

关键词： Viscosity Antenna measurements Electromagnetic interference Vacuum technology Bending Extraterrestrial measurements Radomes MCDM Electromagnetics Testing

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Improving the Adhesion of Cold Sprayed Al Deposits Through In-Situ Micro-Forging

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SSRN 2023年

作者： Luo, Xiao-Tao Liu, Xingke Wei, Yingkang Li, Chang-Jiu State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi’an Jiao Tong University Shaanxi Xi’an710049 China

The much lower processing temperature makes cold spray have many merits to deposit metallic coatings, repair failed metallic parts and additively manufacture metallic parts as compared with the high-energy beam based metal depositing processes. Although adhesion is critical for coating and repairing applications for cold sprayed deposits, it is still challenging to get high bonding strength especially for depositing materials with low density and elastic modulus. Here we introduced an in-situ micro-forging (MF) effect to cold spray by mixing 200-300 μm big-sized 410 stainless steel shot peening particles into the depositing Al powder. Due to the in-situ forging by the shot peening particles with 100 time higher kinetic energy than the depositing Al particle, vortex-like material intermixing between the Al deposit and the AZ31BMg substrate is periodically formed along the deposit/substrate interface. Meanwhile, the greatly improved interfacial plastic deformation at the deposit/substrate interface remarkably promotes the breaking and segmentation of the native oxide scale on both the spraying particle surface and substrate surface which promotes metallurgical bonding formation across the deposit/substrate interface. Both the vortex-like material intermixing induced enhanced mechanical interlocking and the improved metallurgical bonding contribute to a higher adhesion. As a consequence, the adhesion of Al deposit increases from 47.9 MPa to 107.2 MPa. © 2023, The Authors. All rights reserved.

关键词： Kinetics

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Study on the Boost Converter with Parasitic Parameters of SiC MOSFET 7

Study on the Boost Converter with Parasitic Parameters of Si...

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2021 7th International Symposium on Sensors, Mechatronics and Automation System, ISSMAS 2021

作者： Yin, Yifan Mechanical and Materials Science Department Swanson School of Engineering University of Pittsburgh PA15261 United States

As a new type of transistors, SiC MOSFETs have excellent performance on switching speed and are capable to improve the energy efficiency and energy density of power conversion devices. On the other hand, the parasitic parameters associated with them bring potential problems when designing switching regulators or analysing the converter performances. In this paper, a boost converter model based on the switching characteristics of SiC MOSFETs is presented for describing the power conversion behaviours comprehensively and accurately. Applying that model, a feedback control system is designed and simulated to explore the influence of each parasitic capacitance on the boost converter. Also, the power loss of the converter during steady operation is analysed and simulated. The research method and simulation results in this paper can be referenced for the design of boost converter with parasitic parameters of SiC MOSFET. © Published under licence by IOP Publishing Ltd.

关键词： Boost converter

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Nanometer-Scale Acoustic Wave Packets Generated by Stochastic Core-Level Photoionization Events

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Physical Review X 2024年第4期14卷 041010页

作者： Yijing Huang Peihao Sun Samuel W. Teitelbaum Haoyuan Li Yanwen Sun Nan Wang Sanghoon Song Takahiro Sato Matthieu Chollet Taito Osaka Ichiro Inoue Ryan A. Duncan Hyun D. Shin Johann Haber Jinjian Zhou Marco Bernardi Mingqiang Gu James M. Rondinelli Mariano Trigo Makina Yabashi Alexei A. Maznev Keith A. Nelson Diling Zhu David A. Reis Department of Physics Stanford PULSE Institute Department of Applied Physics Stanford Institute for Materials and Energy Sciences Dipartimento di Fisica e Astronomia “Galileo Galilei” Department of Mechanical Engineering SLAC National Accelerator Laboratory Menlo Park California 94025 USA 1-1-1 Kouto Sayo-cho Sayo-gun Hyogo 679-5148 Japan Department of Chemistry Department of Applied Physics and Materials Science Department of Materials Science and Engineering

We demonstrate that the absorption of femtosecond hard x-ray pulses excites quasispherical, high-amplitude, and high-wave-vector coherent acoustic phonon wave packets using an all hard-x-ray pump-probe scattering experiment. The time- and momentum-resolved diffuse scattering signal is consistent with an ensemble of 3D strain wave packets induced by the rapid electron cascade dynamics following photoionization at uncorrelated excitation centers. We quantify key parameters of this process, including the localization size of the stress field and the photon energy conversion efficiency into elastic energy. The parameters are determined by the photoelectron and Auger electron cascade dynamics, as well as the electron-phonon interaction. In particular, we obtain the localization size of the observed strain wave packet to be 1.5 and 2.5 nm for bulk SrTiO3 and KTaO3 single crystals, respectively. The results provide crucial information on the mechanism of x-ray energy deposition into matter and shed light on the shortest collective length scales accessible to coherent acoustic phonon generation using x-ray excitation.

关键词： Electron relaxation Electron-phonon coupling Light-matter interaction Phonons Ultrafast phenomena Oxides Perovskites Semiconductors Ultrafast femtosecond pump probe Ultrafast pump-probe spectroscopy X-ray scattering

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Piezo-/ferroelectric phenomena in biomaterials: A brief review of recent progress and perspectives

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science China(Physics,Mechanics & Astronomy) 2020年第7期63卷 29-46页

作者： Yao Sun KaiYang Zeng Tao Li Department of Mechanical Engineering National University of SingaporeSingapore 546080Singapore Center for Spintronics and Quantum Systems State Key Laboratory for Mechanical Behavior of MaterialsSchool of Materials Science and EngineeringXi'an Jiaotong UniversityXi'an 710049China

There have been overwhelming observations of piezo-/ferroelectric phenomena in many biological tissues and macromolecules,boosting the development of bio-based smart devices and the applications using electromechanical coupling phenomena in biological *** electromechanical coupling is believed to be responsible for various biophysical behaviors and remarkable biomaterial *** the abundant phenomenal observations,the fundamental understanding of the piezo-/ferroelectric effect in biomaterials/systems and the rational design of biobased macroscopic materials with desired piezoelectric responses are still *** this review,we firstly present remarkable historical events on the development of piezo-/ferroelectricity in biomaterials,followed by a brief overview of the fundamental physics of piezo-/*** developments of biopiezo-/bioferroelectricity in protein-based biomaterials and their implications are highlighted *** experimental studies,to identify the intrinsic piezo-/ferroelectric properties from other effects or artifacts is usually *** issue is also addressed and discussed in detail,especially using piezoelectric force microscopy(PFM)and spectroscopy techniques to investigate the local piezo-/ferroelectric phenomena in nanostructured materials are highlighted emphatically.

关键词： biomaterials electromechanical coupling piezoelectric ferroelectric piezoresponse force microscopy

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Separation of Nonionic Surfactant-Stabilized Oil-in-Water Emulsion by Electrolytes

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SSRN 2024年

作者： Alanazi, Khalid Mohan, Ram Kolla, Srinivas Swaroop Shoham, Ovadia Department of Mechanical Engineering The University of Tulsa TulsaOK74104 United States Materials Science and Engineering Oklahoma State University TulsaOK74106 United States McDougall School of Petroleum Engineering The University of Tulsa TulsaOK74104 United States Department of Mechanical Engineering University of Tabuk Tabuk47512 Saudi Arabia

HypothesisThe ionized aqueous solution and the temperature of liquid-liquid mixtures influence the precipitation of hydrophilic nonionic surfactants. Therefore, even if stored at higher temperatures, electrolyte-free oil-in-water emulsions are expected to be very stable. However, once ions are combined with elevated temperatures, the surfactant cloud point will drop significantly leading to immediate separation of the *** tension data of Tergitol 15-S-7 aqueous solution were collected before and after the addition of monovalent and divalent ions. Next, the effect of such ions on emulsions stabilized by Tergitol 15-S-7 was evaluated. The study further emphasized the effect of mixing speed, temperature, and oil fraction on the stability of oil-in-water ***-free oil-in-water emulsions were found to be very stable even when stored at temperatures above the cloud point of the surfactant. However, upon introducing ions to emulsions stored at elevated temperatures, a full separation took place within seconds. Surface tension data of Tergitol 15-S-7 solution showed marginal effects to the presence of ions. © 2024, The Authors. All rights reserved.

关键词： Nonionic surfactants

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Investigation of the High-Temperature Fatigue Mechanism Related to Altered Local Short-Range Order in Al6xn Austenitic Stainless Steel

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SSRN 2023年

作者： Hong, Yanyan Gao, Jun Liu, Xuqiang Wang, Yan-Dong School of Mechanical and Electrical Engineering Wuhan Business University Wuhan430056 China Key Laboratory for Anisotropy and Texture of Materials School of Materials Science and Engineering Northeastern University Shenyang110004 China

An increase in crystal local short-range order (SRO), characterized by obvious diffuse intensity maxima at 1/3{422} in the [111]-axis selected area diffraction pattern, was evidenced by aberration-corrected transmission electron microscopy observations of AL6XN austenitic stainless steel subjected to high-temperature low-cycle fatigue deformation. The SRO structure can be well explained by the ordering arrangement of segregated Cr and Mo atomic layers along the {422} crystal plane in austenite, which was possibly promoted by N atoms segregation and was preferably observed at the planar slip bands: Synchrotron-based X-ray microdiffraction (μXRD) experiment indicates that the distribution of SRO presents a band-like feature. In situ high-energy X-ray diffraction (HE-XRD) experiments were further performed to investigate the deformation behavior of both as-received and fatigued samples under uniaxial loading. The lattice strain evolution revealed an interesting lattice expansion in the initial elastic stage, which provided direct evidence of a decrease in SRO during further uniaxial tensile deformation, indicating that the deformation modes greatly affect the SRO transition. We believe that the high-temperature fatigue damage originated mainly from the accumulation of planar slip bands accompanied by a localized increase in SRO, which promotes work hardening near the final fatigue fracture. © 2023, The Authors. All rights reserved.

关键词： X ray diffraction

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β-relaxation anomaly with low modulus and enhanced recoverable strain in strain glasses crossover

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Acta Materialia 2025年 286卷

作者： Liang, Chuanxin Wang, Dong Ji, Yuanchao Zhang, Jian Ren, Xiaobing Wang, Yunzhi Center of Microstructure Science Frontier Institute of Science and Technology State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an710049 China Frontier Institute of Science and Technology MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an710049 China Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology School of Mechanical Engineering Jiangnan University Wuxi214122 China Ferroic Physics Group National Institute for Materials Science Ibaraki Tsukuba305-0047 Japan Department of Materials Science and Engineering The Ohio State University 2041 College Road ColumbusOH43210 United States

The β-relaxation phenomenon in glasses has shown important effects on toughness, ductility, and creep. However, such a β-relaxation has not been reported yet in an important class of glassy materials, ferroic glasses. Here, we report the existence of a β-relaxation anomaly and its physical origin in strain glass systems by combining molecular statics calculation and phase field simulation. The resolved β-relaxation is observed below the strain glass transition temperature at a critical composition accompanied with spontaneous strain glass to normal martensitic phase transformation, and the internal friction for this β-relaxation anomaly fits well with the Arrhenius equation. The superelasticity with β-relaxation has shown low modulus with high recoverable strain over a wide temperature range. Calculated microstructural evolution and the local stress field caused by point defects suggest that the formed percolation-like metastable suppression field under cooling could be the physical origin of the β-relaxation in strain glass systems and is correlated with crystallization. © 2024 Acta Materialia Inc.

关键词： Point defects

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Gold Nanostars-AIE Theranostic Nanodots with Enhanced Fluorescence and Photosensitization Towards Effective Image-Guided Photodynamic Therapy

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Nano-Micro Letters 2021年第4期13卷 43-57页

作者： Mohammad Tavakkoli Yaraki Min Wu Eshu Middha Wenbo Wu Soroosh Daqiqeh Rezaei Bin Liu Yen Nee Tan Institute of Materials Research and Engineering Agency for ScienceTechnology and Research(A*STAR)Singapore 138634Singapore Department of Chemical and Biomolecular Engineering National University of Singapore4 Engineering Drive 4Singapore 117585Singapore Department of Mechanical Engineering National University of Singapore9 Engineering Drive 1Singapore 117575Singapore Faculty of Science Agriculture and EngineeringNewcastle UniversityNewcastle Upon Tyne NE17RUUK Newcastle Research and Innovation Institute(NewRIIS) 80 Jurong East Street 21#05‑04Singapore 609607Singapore

Dual-functional aggregation-induced photosensitizers(AIE-PSs)with singlet oxygen generation(SOG)ability and bright fluorescence in aggregated state have received much attention in image-guided photodynamic therapy(PDT).However,designing an AIE-PS with both high SOG and intense fluorescence via molecular design is still *** this work,we report a new nanohybrid consisting of gold nanostar(AuNS)and AIE-PS dots with enhanced fluorescence and photosensitization for theranostic *** spectral overlap between the extinction of AuNS and fluorescence emission of AIE-PS dots(665 nm)is carefully selected using five different AuNSs with distinct localized surface plasmon(LSPR)*** show that all the AuNS s can enhance the 1 O2 production of AIE-PS dots,among which the AuNS with LSPR peak at 585 nm exhibited the highest 1 O2 enhancement factor of15-fold with increased fluorescence *** the best of our knowledge,this is the highest enhancement factor reported for the metalenhanced singlet oxygen generation *** Au585@AIE-PS nanodots were applied for simultaneous fluorescence imaging and photodynamic ablation of HeLa cancer cells with strongly enhanced PDT efficiency in *** study provides a better understanding of the metal-enhanced AIE-PS nanohybrid systems,opening up new avenue towards advanced image-guided PDT with greatly improved efficacy.

关键词： Plasmon enhancement Photosensitizer Aggregation-induced emission Fluorescence imaging Theranostics

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Quantifying Electrochemical Processes in Batteries and Beyond

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Energy & Environmental materials 2022年第4期5卷 1001-1004页

作者： Emma N.Antonio Michael F.Toney Materials Science and Engineering Program University of Colorado BoulderBoulderColorado 80309USA Joint Center for Energy Storage Research(JCESR) University of Colorado BoulderBoulderColorado 80309USA Department of Chemical and Biological Engineering University of Colorado BoulderBoulderColorado 80309USA Renewable and Sustainable Energy Institute University of Colorado BoulderBoulderColorado 80309USA

The correlation of electrochemical measurements with materials characterization has advanced our understanding of operation and degradation mechanisms in electrochemical energy storage and many other ***,often these correlations are qualitative,preventing the unambiguous identification of both operational principles and the root causes of performance *** we suggest quantitative approaches to define competing mechanisms and determine their relative *** illustrate the importance of quantitative methodologies over a range of electrochemical systems and highlight the need to consider the effect of the experimental design and measurement *** approaches will reveal the most detrimental degradation mechanisms and enable the development of strategies to suppress,stabilize or eliminate them,leading to materials and devices with longer lifetimes,reduced environmental impact,and improved performance.

关键词： electrochemistry in situ and operando characterization batteries quantification materials science

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