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10th International Conference on Local mechanical Properties, LMP 2013

作者： Burik, Peter Pešek, Ladislav Voleský, Lukáš Technical University of Liberec Faculty of Mechanical Engineering Department of Material Science Studentská 2 461 17 Liberec Czech Republic Technical University of Košice Faculty of Metallurgy Department of Materials Science Letná 9 042 00 Košice Slovakia

ISBN: (纸本)9783038350620

mechanical properties by depth sensing indentation are derived from the indentation load-displacement data used a micromechanical model developed by Oliver & Pharr (O&P). However, O&P analysis on the indentation unloading curve is developed from a purely elastic contact mechanics (sink-in). The applicability of O&P analysis is limited by the materials pile-up. However, when it does, the contact area is larger than that predicted by elastic contact theory (material sinks-in during purely elastic contact), and both hardness H and Young's modulus E are overestimated, because their evaluation depends on the contact area deduced from the loaddisplacement data. H can be overestimated by up to 60 % and E by up to 30 % depending on the extent of pile-up [1,2]. It is therefore important to determine the effect of pile-up on obtained mechanical characteristics of the material by depth sensing indentation. The work experimentally analyses the effect of pile-up height on mechanical characteristics H and E, which are determined by O&P analysis. Pile-up height was measured by atomic force microscopy (AFM). © (2014) Trans Tech Publications, Switzerland.

关键词： Atomic force microscopy

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Abstracts from Hydrocephalus 2016 Abstracts

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FLUIDS AND BARRIERS OF THE CNS 2017年第SUPPL 1期14卷 1-21页

作者： [Anonymous] Johns Hopkins University Baltimore MD USA. Department of Neurosurgery Johns Hopkins University Baltimore MD USA. Johns Hopkins Biostatistics Center Johns Hopkins Bloomberg School of Public Health Baltimore MD USA. Johns Hopkins Bloomberg School of Public Health Baltimore MD USA. Department of Neurosurgery Johns Hopkins University School of Medicine Baltimore MD USA. Johns Hopkins Aramco Healthcare Dhahran Saudi Arabia. Johns Hopkins Hopkins Aramco Healthcare Dhahran Saudi Arabia. Johns Hopkins Aramco Healthcare Ras Tanura Saudi Arabia. Primary Care Johns Hopkins Aramco Healthcare Ras Tanura Saudi Arabia. Bloomberg School of Public Health Johns Hopkins University Baltimore MD USA. Department of Neurosurgery Rhode Island Hospital Providence RI USA. Department of Epidemiology Johns Hopkins Bloomberg School of Public Health Baltimore MD USA. The Interface Group Institute of PhysiologyUniversity of Zurich Zurich Switzerland. Institute of Physiology University of Zurich Zurich Switzerland. Neuroscience Center Zurich and the Zurich Center for Integrative Human Physiology University of Zurich Zurich Switzerland. BioFlowImage Laboratory University of Picardie Jules Verne Amiens France. Reims Mathematics Laboratory University of Reims Champagne-Ardenne Reims France. Image Processing Laboratory University Hospital of Amiens-Picardie Amiens France. BioFlowImage Laboratory Department of Medical Image Processing University Hospital of Picardie Jules Verne Amiens France. Department of Geriatric University Hospital of Toulouse Toulouse France. Departments of Geriatric University Hospital of Toulouse Toulouse France. Department of Geriatry University Hospital Toulouse Toulouse France. Neurosciences department University of Cambridge Cambridge UK. Brain Physics Lab Academic Neurosurgery University of Cambridge Cambridge UK. Department of Nuclear Medicine University Hospital of Toulouse Toulouse France. Department of Nuclear Medicine University Hospit

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Electronic transport characterization of BiVO₄ using AC field hall technique

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Journal of British Studies 2014年第3期1633卷 43-49页

作者： Lindemuth, Jeffery Rettie, Alexander J. E. Marshall, Luke G. Zhou, Jianshi Mullins, C. Buddie Lake Shore Cryotronics Westerville 43082 OH United States McKetta Department of Chemical Engineering University of Texas Austin 78712 TX United States Center for Electrochemistry Department of Chemistry and Biochemistry University of Texas Austin 78712 TX United States Materials Science and Engineering Program Department of Mechanical Engineering University of Texas Austin 78712 TX United States

Bismuth vanadate (BiVO4) is a photoelectrode for the oxidation of water. It is of fundamental importance to understand the electrical and photoelectrochemical properties of this material. In metal oxides, the electronic transport is described by the small polaron model, first described by Mott. In this model, the resistivity varies with temperature as ρ(T) Te (E_a(k_BT)), where E_a is the hopping activation energy, k_B is the Boltzmann constant and T is the absolute temperature. Resistivity measurements confirm that small polaron hopping dominates in temperature ranges from 250 K to 300 K. In addition measurements from 175K to 250K show the variable range hopping dominates the transport. To this end, the electronic transport properties of BiVO4 single crystal were characterized using resistivity measurements and Hall effect measurements over temperatures ranging from 175 K to 300 K. © 2014 materials Research Society.

关键词： Bi electronic material V

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CALPHAD and cluster dynamics modeling of Ni-Mn-Si precipitate stability and kinetics in reactor pressure vessel steels

CALPHAD and cluster dynamics modeling of Ni-Mn-Si precipitat...

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2014 ANS Winter Meeting and Nuclear Technology Expo

作者： Morgan, Dane Ke, Huibin Xiong, Wei Barnard, Leland Wells, Peter Odette, G. Robert Department of Materials Science and Engineering University of Wisconsin MadisonWI United States Materials Science Program University of Wisconsin MadisonWI United States Materials Department University of California Santa BarbaraCA United States Mechanical Engineering University of California Santa BarbaraCA United States

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Development of new generation bone graft material: Silver, silicon co-substituted apatite with bi-functional properties

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Prehospital and Disaster Medicine 2014年第1期1626卷 mrsf13-1626-k09-05-mrsf13-1626-k09-05页

作者： Lim, Poon Nian Chang, Lei Ho, Bow Tay, Bee Yen Cleo, Choong Thian, Eng San Department of Mechanical Engineering National University of Singapore 9 Engineering Drive 1 Singapore 117 576 Singapore Department of Microbiology Yong Loo Lin School of Medicine National University of Singapore 5 Science Drive 2 Singapore 119757 Singapore Singapore Institute of Manufacturing Technology 71 Nanyang Drive Singapore 638 075 Singapore School of Material Science and Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639 798 Singapore

With the rise of ageing population, the need to restore the function of degenerative bone greatly drives the market for bone grafts. Hydroxyapatite (HA) is chemically similar to natural bone mineral and has been widely used in bone graft applications. However, its slow osseointegration process and lack of antibacterial property could lead to implant-related infection, resulting in implant failure. Studies on ionic substitution of apatite have gained attention in recent years with greater understanding of the composition of bone mineral being a multi-substituted apatite. An integrated approach is proposed by co-substituting silver (Ag) and silicon (Si) into HA (Ag,Si-HA) to modify its surface for bi-functional properties. Incorporation of Si can enhance the biomineralization of HA and introduction of Ag can create antibacterial property. Ag,Si-HA containing 0.5 wt.% of Ag and 0.8 wt.% of Si was prepared by a wet precipitation method. A phase-pure apatite with a nanorod morphology of dimensions 60 nm in length and 10 nm in width was synthesized. Surface Ag⁺ ions of Ag,Si-HA were demonstrated to prevent the replication of adherent Staphylococcus aureus bacteria for up to 120 h. Biocompatibility tests revealed that human adipose-derived mesenchymal stem cells (hMSCs) proliferated well on Ag,Si-HA with culturing time. Enhanced cell attachment in turn permitted greater bone differentiation as evidenced in the increase of collagen type I and osteocalcin expressions of hMSCs cultured on Ag,Si-HA as compared to HA from day 14 onwards. Overall, co-substitution of Ag and Si could complement the benefits of each substituent by endowing HA with antibacterial property, and concurrently promoting its biological performance. Their synergistic effects can serve unmet medical needs and solve the problem of implant-related infection. This work also enhances the understanding of substituted apatite with multiple ions for bi-functional properties. © materials Research Society

关键词： Ag biomaterial Si

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Melting and solidification of nanoparticles: Scale effects, thermally activated surface nucleation, and bistable states

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Physical Review B 2014年第7期89卷 075427-075427页

作者： Valery I. Levitas Kamran Samani Department of Aerospace Engineering Department of Mechanical Engineering and Department of Material Science and Engineering Iowa State University Ames Iowa 50011 USA Department of Aerospace Engineering Iowa State University Ames Iowa 50011 USA

Previously unknown phenomena, scale, and kinetic effects are revealed by introducing the finite width Δξ of the particle-exterior interface as the additional scale parameter and thermally activated melting in the phase field approach. In addition to traditional continuous barrierless premelting and melting for Δξ= 0, barrierless hysteretic jumplike premelting (melting) and thermally activated premelting (melting) via critical nucleus are revealed. A very rich temperature θ−Δξ transformation diagram is found, which includes various barrierless and thermally activated transformations between solid, melt, and surface melt, and complex hysteretic behavior under various temperature and Δξ trajectories. Bistable states (i.e., spontaneous thermally activated switching between two states) between solid and melt or surface melt are found for Al particles. Strong dependence of the melting temperature (which, in contrast to previous approaches, is defined for thermally activated premelting and melting) for nanoparticles of various radii on Δξ is found. Results are in good agreement with experiments for Al for Δξ=0.8–1.2nm. They open an unexplored direction of controlling surface melting and melting or solidification by controlling the width of the external surface and utilizing predicted phenomena. They also can be expanded for other phase transformations (e.g., amorphization, solid-solid diffusionless, diffusive, and electromagnetic transformations) and phenomena, imbedded particles, and mechanical effects.

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Increased resistance to mechanical shock of metallic materials by metal-ceramic surface coatings 6

Increased resistance to mechanical shock of metallic materia...

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6th International Conference on Biomaterials, Tissue engineering and Medical Devices, BiomMedD 2014

作者： Biniuc, Carmen Istrate, Bogdan Munteanu, Corneliu Dorin, Luca Technical University Gh. Asachi Faculty of Mechanical Engineering Street. D. Mangeron No.43 Iasi700050 Romania Technical University Gh. Asachi Faculty of Science and Material Engineering Street. D. Mangeron No.41 Iasi700050 Romania

ISBN: (纸本)9783038354321

Recently, material engineering has developed materials' design and processing technology with well-defined goals. Thus, there were designed and achieved metal alloys, meant to be used in areas under powerful mechanical shock, using methods of surface engineering. For this, there have been developed superficial deposition techniques by thermal spray of ceramic and metal powders, both for hard coating, but also to protect surfaces in refractory environments. In a controlled manner, there can be formed new structures, which lead us to an improvement in the tribological properties of the coatings obtained. In this paper, there are described the experimental results obtained from the tests of resistance to mechanical shock of metal-ceramic coatings on forged titanium support. We analyzed the behaviour of thermal deposited layers of ZrO2 stabilized with 8% Y2O3 and Al2O3 after applying the mechanical shock test and scratch test. These materials were analyzed in terms of structural, of mechanical properties and adhesion of the surface layers using electron microscopy, X-ray diffraction. The results showed that the investigated materials have a stratified columnar structure, presenting lamellar and intra - lamellar cracks and pores formed between neighbour "splats". From microscopic analysis, after these tests, it was observed that the thermal deposited layers were not separated and there was a fingerprint on their surface. The experimental results show that the new structures obtained present much better mechanical properties compared to the material, forged titanium, with no deposit. © (2015) Trans Tech Publications, Switzerland.

关键词： Powder metals

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Numerical simulation of membrane desalination in a conjugated heat transfer configuration: Role of spacers

Numerical simulation of membrane desalination in a conjugate...

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International Renewable and Sustainable Energy Conference (IRSEC)

作者： Isam Janajreh Raed Hashaikeh Dana Suwwan Mechanical Engineering Program Masdar Institute of Science and Technology Abu Dhabi UAE Materials Engineering Program Masdar Institute of Science and Technology Abu Dhabi UAE

The performance of the Direct Contact Membrane is assessed via the Computational Fluid Dynamics (CFD) simulation. The developed conjugated heat numerical model from the authors' previous work is used t investigate the role of spacer on the flow and DCMD metrics. The feed (hot stream) and permeate (cold stream) channels are subjected to uniform Navier-Stokes flow and are thermally coupled with a hydrophobic membrane polyvinylidene fluoride (PVDF) in conjugate heat transfer formulation. Depending on the membrane properties (permeability, thickness, pour size, conductivity, etc.) a temperature, and therefore, a pressure gradient across the membrane is created leading to vaporizing, transporting, and condensing the feed at the permeate side. This work investigates the influence of the spacers in modifying the thermal and kinetic boundary layers, i.e. adjustment of surface temperature, heat flux, and shear stress. The DCMD membrane mass transfer coefficient is evaluated additional to the temperature polarization factor (TPF) and thermal efficiency. Results showed a significant change in Temperature, Nusselts number, and surface shear stresses when spacers are introduced as the boundary layer became fully turbulent which enhanced the mass and heat flux but to a smaller extent.

关键词： Lead Heating Feeds

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High energy density, high operating frequency and energy efficient on-chip inductors based on coiled carbon nanotubes (CCNTs)

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2013 MRS Spring Meeting

作者： Faraby, H. Bandaru, P.R. Department of Electrical and Computer Engineering University of California San Diego San Diego CA 92093-0407 United States Department of Mechanical and Aerospace Engineering Materials Science Program University of California San Diego San Diego CA 92093-0411 United States

ISBN: (纸本)9781605115283

We demonstrate the superior inductive properties of coiled carbon nanotubes (CCNTs) through numerical computation and analytical modeling, for the next generation of nanoscale, on-chip inductors. Taking advantage of the kinetic inductance (Lk), particularly evident at the nanoscale we find that the inductance can be increased by three orders of magnitude through changing the tube radius as well as the coil radius while the device footprint of the CCNTs can be reduced by 60%. By varying the geometric parameters of the coiled structure, the external magnetic inductance (***) can be as high as 20% of the Lk. We also report that the self resonant frequency (fSR) of CCNTs can be as much of the order of THz whereas the f SR of conventional copper(Cu) spiral inductors are limited to around 40GHz. Moreover when the material volume is considered, CCNTs have the potential to achieve Quality Factor (Q) eight times as Cu and when the footprint volume is considered O can be twice as Cu All these promising properties of CCNTs make them a potential candidate for the entire frequency spectrum. © 2013 materials Research Society.

关键词： Inductance

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A driving assistance for a powerd wheelchair on a pedestrian flows

A driving assistance for a powerd wheelchair on a pedestrian...

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作者： Chugo, Daisuke Liu, Zhaoyu Muramatsu, Satoshi Yokota, Sho Sakaida, Yuki Hashimoto, Hiroshi Graduate School of Science and Technology Kwansei Gakuin University Sanda Hyogo Japan Department of Mechanical Engineering Toyo University Kawagoe Saitama Japan Nagoya Aichi Japan Master Program of Innovation for Design and Engineering Advanced Institute of Industrial Technology Shinagawa Tokyo Japan

ISBN: (纸本)9781479940325

This paper propose a driving assistance scheme for a powered wheelchair with a force feedback function of its joystick. Generally, a powered wheelchair moves in a human coexistence environment such as a pedestrian way and it is important to move on these environments without a feeling of oppression to other people around it. Therefore, we propose a concept of a dynamic personal space which is a region surrounding a person who can feel comfortable psychologically to other person with a moving wheelchair in the pedestrian flows. A dynamic personal space is defined considering with a relative velocity and acceleration between the powered wheelchair and the pedestrians around it. Using this concept, we develop a driving assistance system using a force feedback of its joystick, which enables the powered wheelchair to move in a human coexistence environment without a feeling of oppression on other people. In this paper, we investigate spatial relationship with a powered wheelchair experimentally and define a dynamic personal space using these results. For verifying its effectiveness, the performance of our system is verified by experiments using our prototype. © 2014 IEEE.

关键词： Feedback

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