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[ASME ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - Quebec City, Quebec, Canada (Sunday 26 August 2018)] Volume 1B: 38th Computers and Information in Engineering Conference - High Degree of Freedom Hand Pose Tracking Using Limited Strain Sensing and Optical Training
摘要： The ability to track human operators’ hand usage when working in production plants and factories is critically important for developing realistic digital factory simulators as well as manufacturing process control. We propose an instrumented glove with only a few strain gauge sensors and a micro-controller that continuously tracks and records the hand configuration during actual use. At the heart of our approach is a trainable system that can predict the fourteen joint angles in the hand using only a small set of strain sensors. First, ten strain gauges are placed at the various joints in the hand to optimize the sensor layout using the English letters in the American Sign Language as a benchmark for assessment. Next, the best sensor configurations for three through ten strain gauges are computed using a support vector machine classifier. Following the layout optimization, our approach learns a mapping between the sensor readouts to the actual joint angles optically captured using a Leap Motion system. Three regression methods including linear, quadratic and neural regression are then used to train the mapping between the strain gauge data and the corresponding joint angles. The final proposed model involves four strain gauges mapped to the fourteen joint angles using a two-layer feed-forward neural network.
关键词： digital factory simulators,neural regression,strain gauge sensors,hand pose tracking,Leap Motion
更新于2025-09-09 09:28:46
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A Comparative Analysis of BaTiO3/(Ba,Sr)TiO3 and BaTiO3/(Ba,Sr)TiO3/SrTiO3 Artificial Superlattices via Raman Spectroscopy
摘要： BaTiO3/Ba50Sr50TiO3 and BaTiO3/Ba50Sr50TiO3/SrTiO3 superlattices are characterized via Raman spectroscopy. Special attention is paid to a comprehensive analysis of their polarized Raman spectra, especially, within a soft mode (E(1TO)) range. The shift of E(1TO) soft mode is found to be more pronounced for BaTiO3/Ba50Sr50TiO3/SrTiO3 sample than for BaTiO3/Ba50Sr50TiO3, presumably owing to stronger 2D compression of BT layers and abruptly increased temperature of transition from ferroelectric to paraelectric phase.
关键词： BaTiO3/Ba50Sr50TiO3/SrTiO3 ferroelectric superlattices,Raman spectroscopy,soft mode,strain,BaTiO3/Ba50Sr50TiO3
更新于2025-09-09 09:28:46
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Probing the nanoscale origin of strain and doping in graphene-hBN heterostructures
摘要： We use confocal Raman microscopy and a recently proposed vector analysis scheme to investigate the nanoscale origin of strain and carrier concentration in exfoliated graphene-hexagonal boron nitride (hBN) heterostructures on silicon dioxide (SiO2). Two types of heterostructures are studied: graphene on SiO2 partially covered by hBN, and graphene fully encapsulated between two hBN flakes. We extend the vector analysis method to produce separated spatial maps of the strain and doping variation across the heterostructures. This allows us to visualise and directly quantify the much-speculated effect of the environment on carrier concentration in graphene. Moreover, we demonstrate that variations in strain and carrier concentration in graphene arise from nanoscale features of the heterostructures such as fractures, folds and bubbles trapped between layers. For bubbles in hBN-encapsulated graphene, hydrostatic strain is shown to be greatest at bubble centres, whereas the maximum carrier concentration is localised at bubble edges. Raman spectroscopy is shown to be a non-invasive tool for probing strain and doping in graphene, which could prove useful for engineering of two-dimensional devices.
关键词： hexagonal boron nitride,Raman,strain,van der Waals heterostructures,graphene,hBN,doping
更新于2025-09-09 09:28:46
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Design and investigation of a sensitivity-enhanced fiber Bragg grating sensor for micro-strain measurement
摘要： The fiber Bragg grating (FBG) sensors are widely used in strain measurement. However, the current FBG sensors are not sensitive enough to monitor the micro-strain. In order to provide a feasible method to monitor the micro-strain of lithium-ion battery, a novel fiber Bragg grating (FBG) strain sensors with enhanced sensitivity was developed in this paper. A lever mechanism was adopted to enhance the sensor sensitivity and flexure hinges as well as serpentine springs were used in sensor structure. The sensor structure dimension was optimized through theoretical calculation and finite element analysis, and the optimized sensor was manufactured and tested. The results of calibration test show that in the measuring range of ±500 με, the sensor has strain sensitivity of 11.49 pm/με, good linearity and repeatability as well as tiny hysteresis error. The battery experimental results illustrate there is a same trend between strain and voltage of battery, and a good uniformity under three working modes of battery. This proposed FBG sensor will provide a solution for strain measurement of battery.
关键词： Sensitivity-enhanced,Battery strain measurement,Flexure hinge,FBG sensor
更新于2025-09-09 09:28:46
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Strain-engineering of twist-angle in graphene/hBN superlattice devices
摘要： The observation of novel physical phenomena such as Hofstadter’s butterfly, topological currents and unconventional superconductivity in graphene have been enabled by the replacement of SiO2 with hexagonal Boron Nitride (hBN) as a substrate and by the ability to form superlattices in graphene/hBN heterostructures. These devices are commonly made by etching the graphene into a Hall-bar shape with metal contacts. The deposition of metal electrodes, the design and specific configuration of contacts can have profound effects on the electronic properties of the devices possibly even affecting the alignment of graphene/hBN superlattices. In this work we probe the strain configuration of graphene on hBN contacted with two types of metal contacts, two-dimensional (2D) top-contacts and one-dimensional (1D) edge-contacts. We show that top-contacts induce strain in the graphene layer along two opposing leads, leading to a complex strain pattern across the device channel. Edge-contacts, on the contrary, do not show such strain pattern. A finite-elements modelling simulation is used to confirm that the observed strain pattern is generated by the mechanical action of the metal contacts clamped to the graphene. Thermal annealing is shown to reduce the overall doping whilst increasing the overall strain, indicating and increased interaction between graphene and hBN. Surprisingly, we find that the two contacts configurations lead to different twist-angles in graphene/hBN superlattices, which converge to the same value after thermal annealing. This observation confirms the self-locking mechanism of graphene/hBN superlattices also in the presence of strain gradients. Our experiments may have profound implications in the development of future electronic devices based on heterostructures and provide a new mechanism to induce complex strain patterns in 2D materials.
关键词： Raman,hBN,Graphene,twist-angle,superlattice,strain
更新于2025-09-09 09:28:46
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Engineering SrSnO <sub/>3</sub> Phases and Electron Mobility at Room Temperature Using Epitaxial Strain
摘要： High-speed electronics require epitaxial films with exceptionally high carrier mobility at room temperature. Alkaline-earth stannates with high room-temperature mobility show outstanding prospects for oxide electronics operating at ambient temperatures. However, despite significant progress over the last few years, mobility in stannate films has been limited by dislocations due to the inability to grow fully coherent films. Here, we demonstrate the growth of coherent, strain-engineered phases of epitaxial SrSnO3 (SSO) films using a radical-based molecular beam epitaxy approach. Compressive strain stabilized the high-symmetry tetragonal phase of SSO at room temperature (RT), which, in bulk, exists only at temperatures between 1062 K and 1295 K. We achieved a mobility enhancement of over 300% in doped films compared with the low temperature orthorhombic polymorph. Using comprehensive temperature-dependent synchrotron-based X-ray measurements, electronic transport and first principles calculations, crystal and electronic structures of SSO films were investigated as a function of strain. We argue that strain-engineered films of stannate will enable high mobility oxide electronics operating at RT with the added advantage of being optically transparent.
关键词： phase transition,Hybrid molecular beam epitaxy,half-order diffraction,strain engineering,density functional theory,high mobility,Octahedral rotations
更新于2025-09-09 09:28:46
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High pressure synthesis of A2NiO2Ag2Se2 (A = Sr, Ba) with a high spin Ni2+ in square planar coordination
摘要： Square-planar coordinate Ni2+ in oxides are exclusively limited to a low spin state (S = 0) owing to extensive crystal field splitting. Here we report layered oxychalcogenides A2NiIIO2Ag2Se2 (A = Sr, Ba) with the S = 1 NiO2 square lattice. The structural analysis revealed that the Ni2+ ion is under-bonded by a significant tensile strain from neighboring Ag2Se2 layers, leading to the reduction in crystal field splitting. Ba2NiO2Ag2Se2 exhibits a G-type spin order at 130 K, indicating fairly strong in-plane interactions. The high-pressure synthesis employed here possibly assists the expansion of NiO2 square lattice by taking the advantage of the difference in compressibility in oxide and selenide layers.
关键词： oxychalcogenide,spin state,high pressure synthesis,strain,square lattice
更新于2025-09-09 09:28:46
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Inverted orbital polarization in strained correlated oxide films
摘要： Manipulating the orbital occupation of valence electrons via epitaxial strain in an effort to induce new functional properties requires considerations of how changes in the local bonding environment affect the band structure at the Fermi level. Using synchrotron radiation to measure the x-ray linear dichroism of epitaxially strained films of the correlated oxide CaFeO3, we demonstrate that the orbital polarization of the Fe valence electrons is opposite from conventional understanding. Although the energetic ordering of the Fe 3d orbitals is confirmed by multiplet ligand field theory analysis to be consistent with previously reported strain-induced behavior, we find that the nominally higher energy orbital is more populated than the lower. We ascribe this inverted orbital polarization to an anisotropic bandwidth response to strain in a compound with nearly filled bands. These findings provide an important counterexample to the traditional understanding of strain-induced orbital polarization and reveal a method to engineer otherwise unachievable orbital occupations in correlated oxides.
关键词： x-ray linear dichroism,epitaxial strain,CaFeO3,correlated oxides,orbital polarization
更新于2025-09-09 09:28:46
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Difference analysis model for the mismatch effect and substrate-induced lattice deformation in atomically thin materials
摘要： Atomically thin materials hold mutative electronic transition properties by virtue of the inevitable strains adding to the lattice distribution. A quantitative approach and clear systematical verification have seldom been presented to effectively illustrate the substrate-induced strain along the lattice distribution, although the substrate perturbations for monolayers have been repeatedly mentioned. Here, a model of difference analysis is introduced to reveal the structural strain of monolayers from the substrate, which is derived from the mismatch effect based on the variation of the thermal expansion coefficient between the substrate and monolayers. A coupling coefficient is proposed to quantitatively manifest the substrate-induced strain and mismatch effect. Furthermore, combined with the coupling coefficient, the lattice disorder from the mismatch effect is demonstrated, experimentally using the WS2 monolayer as reference. This study could promote broad investigations of some fundamental issues from preparation to electrical structural performances in atomically thin materials and further practical applications.
关键词： atomically thin materials,substrate-induced strain,mismatch effect,WS2 monolayer,thermal expansion coefficient
更新于2025-09-09 09:28:46
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Equi-biaxial compressive strain in graphene: Grüneisen parameter and buckling ridges
摘要： Here we report equi-biaxial compressive strain in monolayer graphene on SiO2 and Si3N4 substrates induced by thermal cycling in vacuum. The equi-biaxial strain is attributed to the mismatch in coefficient of thermal expansion between graphene and the substrate and sliding of graphene on the substrate. Importantly, the induced buckling ridges in graphene exhibit a pattern representing the symmetry of graphene crystal structure, which agreed well with our molecular dynamics (MD) simulations. Furthermore, these thermally-induced buckling ridges were found reminiscent of those in graphene synthesized by the CVD and SiC sublimation methods, suggesting the same origin of formation of the buckling ridges.
关键词： biaxial strain,thermal cycling,graphene,buckling ridges,molecular dynamics simulation,Grüneisen parameter
更新于2025-09-09 09:28:46