- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Femtosecond Optical Annealing Induced Polymer Melting and Formation of Solid Droplets
摘要： Interaction between femtosecond laser pulses with polymeric thin films induced transient optical annealing of the polymer molecules. Melting of the polymer films took place during the transient annealing process, so that a solid-liquid-solid phase transition process was observed. Ultrafast cooling of the melting polymer produced solidified droplets. Microscopic and spectroscopic characterization revealed that the polymer molecules were rearranged with preferable H-aggregation to reach the lowest formation energy during the melting process. Intermolecular coupling was enhanced due to the modified molecular arrangement. This observation of melting of polymeric semiconductors due to the interaction with femtosecond light pulses is potentially important for better understanding laser-matter interactions and for exploring organic optoelectronic devices through special material processing.
关键词： transient optical annealing,melting polymer droplets,solid-liquid-solid phase transition,femtosecond laser-matter interaction,molecular rearrangement
更新于2025-09-23 15:22:29
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A camera based human computer interaction through virtual keyboard assistant
摘要： Human Computer Interaction has evolved with time and exploited almost all the possible relationships that human can have with computers. The present scenario of using the computer is often inaccessible to people with severe motor impairment, which cannot inhabit the traditional keyboard and mouse, and require another specialized input device. A Camera mouse Human-Computer Interface (HCI) based virtual assistant is designed and planned to be evaluated with 15 subjects and hoped to work for individuals with advanced Amyotrophic Lateral Sclerosis (ALS), all of whom were given tasks to execute through the virtual assistant. In the proposed system, this includes primarily, a virtual keyboard with an embedded Internet browser. The virtual keyboard allows users with movement impairments, basically hand movement issues, to directly interact with the computer. The keyboard has varied functions, apart from just typing; namely, searching anything on google, login to social media and checking emails, text to speech facilities and has a database that holds all the basic helper commands for the person. The camera mouse is software that allows people to interact with the computer by registering any part of their body and then using that part as the pointing device to work on the computer system. The participants of the evaluation will be both, subjects that have knowledge about the HCI interface and those completely new to it. We define additional criteria for unrestricted internet access for evaluation of the presented and future internet browsers, Camera based browser provides unrestricted access and enables free web surfing for individuals with motor impairments. This system improves the subject’s quality of life and provides uninterrupted access for the subject to use the computer.
关键词： Camera,Virtual keyboard,Graphical User Interface,Human computer Interaction
更新于2025-09-23 15:22:29
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Field dependence of THz spectra of effective models for <i>α</i> -RuCl <sub/>3</sub>
摘要： We calculate polarized terahertz (THz) spectra of two effective models for a honeycomb-lattice magnet α-RuCl3 by using a numerical exact-diagonalization method. One of the two models is the ab initio model proposed in H.-S. Kim and H.-Y. Kee [Phys. Rev. B 93, 155143 (2016)] and the other is the large-|K| model that we have proposed by an empirical way in order to explain experimental results for α-RuCl3. We discuss the magnetic-?eld dependence of the lowest-excitation mode in the polarized THz spectra for the two models. We ?nd that the energy gap of the lowest-excitation mode in both models does not close and increases almost linearly above the critical ?eld, where the zigzag order is suppressed. From the obtained results, we point out that the low-energy excitation is mainly governed not by the Kitaev interaction but by the Heisenberg interaction and the off-diagonal interactions.
关键词： exact-diagonalization method,honeycomb-lattice magnet,α-RuCl3,THz spectra,Heisenberg interaction,Kitaev interaction
更新于2025-09-23 15:21:21
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Coulomb interaction-induced jitter amplification in RF-compressed high-brightness electron source ultrafast electron diffraction
摘要： We have theoretically and experimentally demonstrated an RF compression-based jitter-amplification effect in high-brightness electron source ultrafast electron diffraction (UED), which degrades the temporal resolution significantly. A detailed analysis and simulations reveal the crucial role of the longitudinal and transverse Coulomb interaction for this jitter-amplification effect, which accord very well with experimental results. An optimized compact UED structure for full compression has been proposed, which can suppress the jitter by half and improve the temporal resolution to sub-100 fs. This Coulomb interaction-induced jitter amplification exists in nearly the whole ultrafast physics field where laser-electron synchronization is required. Moreover, it cannot be suppressed completely. The quantified explanation for the mechanism and optimization provides important guidance for photocathode accelerators and other compression-based ultrashort electron pulse generation and precise control.
关键词： system optimization,jitter amplification,RF compression,high-brightness electron source,ultrafast electron diffraction,Coulomb interaction
更新于2025-09-23 15:21:21
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seed layers
摘要： We characterize asymmetric growth of magnetic bubble domains in perpendicularly magnetized Co/Ni multilayers grown on PtxIr1?x seed layers by application of perpendicular and in-plane magnetic fields. Using a refined model of domain wall creep that incorporates contributions from the anisotropic elastic energy, ε, and a chirality-dependent prefactor, v0, we elucidate factors that govern the mobility of Dzyaloshinskii domain walls as a function of seed-layer composition. The interfacial Dzyaloshinskii-Moriya interaction (DMI) magnitude is found to decrease monotonically with xIr, which is independently confirmed by Brillouin light scattering. Moreover, the persistence of significant asymmetry in velocity curves across the full composition range supports previous assertions that a chirality-dependent attempt frequency akin to chiral damping could play a critical role in the observed trends. This work helps resolve fundamental questions about the factors governing Dzyaloshinskii domain-wall creep and demonstrates varying Pt-Ir seed-layer composition as a method to tune DMI.
关键词： Dzyaloshinskii domain-wall creep,PtxIr1?x seed layers,Brillouin light scattering,interfacial Dzyaloshinskii-Moriya interaction,Co/Ni thin films
更新于2025-09-23 15:21:21
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-electron materials: Sn monolayer on a SiC(0001) surface
摘要： Materials with sp magnetism demonstrate strongly nonlocal Coulomb interactions, which opens a way to probe correlations in the regimes not achievable in transition metal compounds. By the example of Sn monolayer on a SiC(0001) surface, we show that such systems exhibit unusual but intriguing magnetic properties at the nanoscale. Physically, this is attributed to the presence of a significant ferromagnetic coupling, the so-called direct exchange, which fully compensates ubiquitous antiferromagnetic interactions of the superexchange origin. Having a nonlocal nature, the direct exchange was previously ignored because it cannot be captured within the conventional density functional methods and significantly challenges ground state models earlier proposed for Sn/SiC(0001). Furthermore, heavy adatoms induce strong spin-orbit coupling, which leads to a highly anisotropic form of the spin Hamiltonian, in which the Dzyaloshinskii-Moriya interaction (DMI) is dominant. The latter is suggested to be responsible for the formation of a nanoskyrmion state at realistic magnetic fields and temperatures.
关键词： Dzyaloshinskii-Moriya interaction,SiC(0001) surface,direct exchange,nonlocal Coulomb interactions,nanoskyrmion state,sp magnetism,Sn monolayer
更新于2025-09-23 15:21:21
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Dipolar Quantum Mixtures of Erbium and Dysprosium Atoms
摘要： We report on the first realization of heteronuclear dipolar quantum mixtures of highly magnetic erbium and dysprosium atoms. With a versatile experimental setup, we demonstrate binary Bose-Einstein condensation in five different Er-Dy isotope combinations, as well as one Er-Dy Bose-Fermi mixture. Finally, we present first studies of the interspecies interaction between the two species for one mixture.
关键词： erbium,dipolar quantum mixtures,Bose-Einstein condensation,interspecies interaction,dysprosium
更新于2025-09-23 15:21:21
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Multisoliton interactions for the Manakov system under composite external potentials
摘要： The soliton interactions of Manakov soliton trains subjected to composite external potentials are modelled by the perturbed complex Toda chain (PCTC). The model is applied to several classes of potentials, such as: (i) harmonic, (ii) periodic, (iii) ‘wide well’-type potentials, and (iv) inter-channel interactions. We demonstrate that the potentials can change the asymptotic regimes of the soliton trains. Our results can be implemented, e.g., in experiments on Bose–Einstein condensates and can be used to control the soliton motion. In general, our numerical experiments demonstrate that the predictions of complex Toda chain (CTC) (respectively PCTC) match very well the Manakov (respectively perturbed Manakov) model numerics for long-time evolution, often much longer than expected. This means that both CTC and PCTC are reliable dynamical models for predicting the dynamics of the multisoliton trains of the Manakov model in adiabatic approximation. This extends our previous results on scalar soliton trains to the Manakov trains with compatible initial parameters.
关键词： adiabatic interaction,perturbed complex Toda chain,Manakov system,breathing of multisoliton trains
更新于2025-09-23 15:21:21
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Triptycene Based Fluorescent Polymers with Pendant Alkyl Chains: Interaction with Fullerene and Morphology of Thin Films
摘要： We report unique triptycene based alternating copolymers bearing long alkyl chains as pendants. Syntheses utilized 2,6-diethynyltriptycene and appropriate alkyloxyarene monomers polymerized via Sonogashira cross coupling reaction to yield triptycene based poly(phenylene ethynylene)s (TPPEs). Resulting polymers are soluble in organic solvents and were characterized by FT-IR, NMR, GPC, TGA, AFM, SEM, UV-visible and fluorescence spectroscopic techniques. Experimental results suggest polymers are thermally stable and fluorescent. The fluorescence emission was quenched in presence of fullerenes (C60 and C70) suggesting their strong host-guest interactions. The magnitude of binding constant between polymer and these fullerenes was determined to be in the order of 105 M-1.The effect of chain length on the morphology and wettability of polymers on silicon substrates were studied using atomic force microscope. Three distinct dewetting patterns viz., spherical domains, fractal and ring structures, were observed with variation in the pendant chain length. This ability to control the thin film morphology of polymers may have potential technological applications, which includes but is not limited to sensors, fluorescent coatings and organic electronics.
关键词： Triptycene,binding interaction with fullerene,AFM,fluorescence
更新于2025-09-23 15:21:21
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[IEEE 2018 27th IEEE International Symposium on Robot and Human Interactive Communication (RO-MAN) - Nanjing, China (2018.8.27-2018.8.31)] 2018 27th IEEE International Symposium on Robot and Human Interactive Communication (RO-MAN) - Passive Demonstrations of Light-Based Robot Signals for Improved Human Interpretability
摘要： When mobile robots navigate crowded, human-populated environments, the potential for conflict arises in the form of intersecting trajectories. This study investigates the use of light-emitting diodes (LEDs) arranged along the chassis of a robot in an arrangement similar to a turn signal on a car as a non-anthropomorphic, yet familiar signal to convey the intended path of a mobile service robot. We study the scenario of a human and a robot heading directly toward each other in a hallway, which may give rise to the familiar human experience in which both parties step to the right, then the left, then the right, continuing to block each other’s paths until they are able to coordinate their movements and pass each other. We conducted a pilot study which revealed that people do not always interpret this signal as one may expect, which would be similar to how a car uses its turn signal. This motivated a 2×2 experiment in which the robot either does or does not use LEDs to indicate its intended direction of travel, and in which study participants either are able to or unable to witness the robot’s “lane-changing” behavior further down the hallway prior to coming into direct proximal contact with the robot. The results demonstrate that exposing participants to the robot’s use of the LED signal only once prior to passing each other in the hallway is sufficient to disambiguate its meaning to the user, and thus greatly enhances its utility in-situ, with no direct instruction or training to the user. These findings suggest a paradigm of passive demonstration of such signals in future applications.
关键词： mobile robots,human-robot interaction,passive demonstration,non-anthropomorphic signals,LED signals
更新于2025-09-23 15:21:21