- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Valley-Hall topological plasmons in a graphene nanohole plasmonic crystal waveguide
摘要： In this paper, we first formulate the confinement-escape problem of a defender and an evader who attempts escaping from a circular region, which differs from the traditional pursuit-evasion problems. In our setting of the confinement-escape problem, the defender is restricted to move and patrol on the circle, trying to prevent possible escape of the evader who is initially located inside the circle. We describe and characterize some general properties of the problem, and then design two bio-inspired control strategies for the evader and the defender, respectively. In addition, we illustrate some possible motion patterns of the system, investigate the escaping time as a function of the relative-initial-positions of the agents, as well as the winning sets of the two players, respectively, under different system-parameters. To that end, we characterize the contour lines of the winning sets with their gradient properties. Finally, we indicate the abrupt phase transitions between successful confinement and escaping, revealing the strong sensitivity and nonlinearities of the system under critical conditions.
关键词： Confinement-escape problem,pursuer-evader,evader,defender,pursuit-evasion,phase transition,patrolling
更新于2025-09-23 15:21:01
-
Brazing, Laser, and Electron-Beam Welding of Additively Manufactured GRCop-84 Copper for Phased Array Lower Hybrid Launchers
摘要： Recent advances in selective laser melting 3-D printing technology allow additive manufacturing of lower hybrid current drive (LHCD) RF launchers from a new material, Glenn Research Copper 84 (GRCop-84), a Cr2Nb (8 at. % Cr, 4 at. % Nb) precipitation hardened alloy, in configurations unachievable by conventional machining. Cr2Nb crystals pin grain boundaries within the copper matrix resulting in high tensile strength and resistance to annealing at elevated temperatures. Brazing, laser, and electron-beam welding (EBW) techniques are explored for joining a thin-walled GRCop-84 waveguide with zero porosity and minimal internal surface roughness. GRCop-84 wets well with the silver solder, CuSil, and Cusil-ABA brazes, once the durable surface oxide is mechanically removed. GRCop-84 melt pool size and flow during EBW is reduced compared to oxygen-free copper (OFC). Pulsed laser and e-beam welding maintains the Cr2Nb precipitate size; precipitate coarsening occurs in conduction mode e-beam welding.
关键词： joining processes,fusion reactor design,magnetic confinement,Annealing,tokamaks,copper alloys,melt processing,materials processing,phased arrays,waveguide
更新于2025-09-23 15:21:01
-
Nanocatalosomes as Plasmonic Bilayer Shells with Interlayer Catalytic Nanospaces for Solara??Lighta??Induced Reactions
摘要： Paramount interest and challenges remain in designing and synthesizing catalysts with nature-like complexities at few-nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”— bio-inspired bilayer-vesicular design of nanoreactor with metallic bilayer hollow shell-in-shell structure, having numerous controllable confined cavities within few-nm interlayer space, customizable with different noble metals. The intershell-confined plasmonically-coupled hot-nanospaces within the few-nm cavities play pivotal role in harnessing synergistic catalytic effects for various transformations, as demonstrated by ‘acceptorless dehydrogenation’, ‘Suzuki-Miayura cross-coupling’ and ‘alkynyl-annulation’ affording clean conversions and TOF at least one order of magnitude higher than state-of-the-art Au-nanorod-based plasmonic-catalysts. This work paves the way towards next-generation nanoreactors, craftable at few-nm scale to maximize their functionality and customizable to carry out diverse chemical transformations efficiently with green solar energy.
关键词： hollow nanostructure,nanocatalyst,bilayer structure,plasmonic-catalytic material,nano-space confinement
更新于2025-09-23 15:21:01
-
Nanocatalosomes as Plasmonic Bilayer Shells with Interlayer Catalytic Nanospaces for Solara??Lighta??Induced Reactions
摘要： Paramount interest and challenges remain in designing and synthesizing catalysts with nature-like complexities at few-nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”— bio-inspired bilayer-vesicular design of nanoreactor with metallic bilayer hollow shell-in-shell structure, having numerous controllable confined cavities within few-nm interlayer space, customizable with different noble metals. The intershell-confined plasmonically-coupled hot-nanospaces within the few-nm cavities play pivotal role in harnessing synergistic catalytic effects for various transformations, as demonstrated by ‘acceptorless dehydrogenation’, ‘Suzuki-Miayura cross-coupling’ and ‘alkynyl-annulation’ affording clean conversions and TOF at least one order of magnitude higher than state-of-the-art Au-nanorod-based plasmonic-catalysts. This work paves the way towards next-generation nanoreactors, craftable at few-nm scale to maximize their functionality and customizable to carry out diverse chemical transformations efficiently with green solar energy.
关键词： hollow nanostructure,nanocatalyst,bilayer structure,plasmonic-catalytic material,nano-space confinement
更新于2025-09-23 15:21:01
-
Graphene for Flexible Lighting and Displays || Graphene-based quantum dot emitters for light-emitting diodes
摘要： Quantum dot is a zero-dimensional material that is introduced from the quantum con?nement effect when it is sized in nanometer scale and has various electrical and optical properties depending on the size of the particle. The electrons con?ned in small areas of nanoscale which are smaller than exciton Bohr radius are quantized and limited in free motion, and electrons in quantum dot are con?ned in every three direction by the quantum con?nement effect which causes a ?nite number of electron, hole, and exciton states, resulting in various characteristics on the size of the particle. In other words, the full con?nement in every three direction results in the complete quantization or discretization of the energy states of con?ned charge carriers in quantum dot [1]. Therefore, the fewer energy levels are quanti?ed as the energy level of the carrier decreases as the particle size decreases, resulting in a wider and more discretized bandgap [2e4].
关键词： electroluminescence,light-emitting diodes,quantum confinement,graphene quantum dots,photoluminescence
更新于2025-09-23 15:21:01
-
Transition kinetics of impurity doped quantum dots under time-dependent confinement potential: role of noise
摘要： Present study endeavors to analyze the role of Gaussian white noise and fluctuating confinement potential on time-average excitation rate (TAER) of impurity doped quantum dot (QD). The TAER profiles are exhaustively monitored as a number of physical quantities are varied over a range with and without noise. Application of noise to the system takes place in two different pathways known as ‘additive’ and ‘multiplicative’. And the fluctuation of the confinement potential has been considered to be cosinusoidal and random which induces the excitation of ground state electronic population to the higher states. The TAER profiles comprise of features like steady increase/decrease, maximization, minimization and saturation. However, the specific characteristics of a particular profile depend on presence/absence of noise, the noise mode, the nature of fluctuating confinement potential and the identity of the physical quantity being varied. Production of large TAER of doped QD depends on noise-mode and nature of fluctuating confinement potential based on which the noise strength is required to be maintained in the vicinity of some typical values.
关键词： additive noise,Gaussian white noise,time-average excitation rate,impurity doped quantum dot,multiplicative noise,fluctuating confinement potential
更新于2025-09-23 15:21:01
-
Square and Hexagonal Columnar Liquid Crystals Confined in Square and Triangular Pores
摘要： Columnar liquid crystals confined in cylindrical pores are known to orient perpendicular to the pore axis, although for potential nanoelectronic applications they would need to be aligned axially. The X-ray diffraction study reveals that while in all three compounds examined, the columns arrange in concentric circles in circular pores, axial alignment is indeed achieved for the hexagonal phase of a discotic hexa-peri-hexabenzocoronene in “triangular pores,” and for the square phase of a T-shaped amphiphile in “square pores.” For the third compound, a carbazole dendron with very soft hexagonal columns, a new three-circle configuration is observed by atomic force microscopy (AFM) in triangular pores. The complex structure of domain walls in columnar liquid crystals is thus seen for the first time on the level of individual columns. A simple estimation of free energies confirms that it is the distortion of polygonal columnar lattice that prevents axial orientation in circular pores. The model also explains the appearance of the three-circle arrangement of soft columns.
关键词： columnar liquid crystals,confinement,axial orientation,triangular pores,square pores
更新于2025-09-23 15:21:01
-
Amplified and Multicolor Emission from Films and Interfacial Layers of Lead Halide Perovskite Nanocrystals
摘要： Lead halide perovskites are promising for energy harvesting and lighting applications. We show amplified emission from films of organic-inorganic or all inorganic lead halide perovskite nanocrystals. Also, multicolor emission is detected from interfacial layers of chloride and bromide perovskites. While amplified emission originates from spatial confinement of manifold charge carriers in films, multicolor emission emanates from interfacial ion exchanged layers. In a film, the amplified emission is averaged over a large number of nanocrystals, which prevents us from detecting any spectral narrowing. Conversely, amplified spontaneous emission (ASE) and spectral narrowing are detected from an isolated perovskite microcrystal. Interestingly, under low intensity excitation, a perovskite nanocrystal film shows unusually delayed emission, which becomes extremely fast and spatially confined at higher intensities of excitation light. By precisely detecting photoluminescence from an irradiated area and outside, we reveal the migration as well as confinement of photogenerated charge carriers in the film. The migration of charge carriers is more efficient in a film of organic-inorganic perovskites than all-inorganic perovskites.
关键词： spatial confinement,multicolor emission,interfacial ion exchange,amplified emission,Lead halide perovskites,charge carriers
更新于2025-09-23 15:21:01
-
Design of quad core photonic crystal fibers with flattened zero dispersion
摘要： Two photonic crystal fiber structures with quad-core have been investigated in this paper. Both the structures are geometrically similar but have different background materials. Both PCF structures exhibit very high birefringence. However, structure with silica background material reports birefringence of the order 10-2. It is to be noted that, this PCF structure has also shown zero dispersion behavior over a wide range of telecommunication wavelength. Moreover, the other structure with lead silicate as background material has also reported very low dispersion. Thus both the PCF structures simulated show ability to mitigate the effect of polarized mode dispersion. Besides this, other propagation characteristics like confinement loss, normalized frequency and non linear coefficient have been reported.
关键词： confinement loss,dispersion,birefringence,nonlinearity,Photonic crystal fibers
更新于2025-09-23 15:21:01
-
The interaction of parametric instabilities from 3?? laser and 2?? laser in large-scale inhomogeneous plasmas
摘要： The interaction of parametric instabilities from 3ω laser and 2ω laser in large-scale inhomogeneous plasmas. The mechanism of energy transfer from 3ω pump light to stimulated Brillouin scattering (SBS) generated by 2ω pump light is proposed. The backscattering light of stimulated Raman scattering (SRS) generated by 3ω pump light can work as a seed of the SBS of 2ω pump light, which results in the increase of the later. Adding 2ω pump light into 3ω pump light will decrease the reflectivity of SBS generated from 3ω pump light. The total reflectivity will firstly decrease and then increase with increase of the ratio of 2ω light intensity to the intensity of 2ω and 3ω lights f = I2ω0/(I2ω0 + I3ω0), and will be controlled in a lower level when this ratio f is about 10% ? 20%. These results give a method to control the total reflectivity of SBS and SRS in inertial confinement fusion (ICF) by adding 2ω light into 3ω light.
关键词： inertial confinement fusion,2ω laser,3ω laser,parametric instabilities,stimulated Raman scattering,stimulated Brillouin scattering,large-scale inhomogeneous plasmas
更新于2025-09-23 15:19:57