Papers by Keyword: Energy Transfer

Abstract: SiO₂ nanoparticles (NPs) are synthesized in ethanol solution and mixed with polyvinyl carbazole (PVK). The sizes of SiO₂ NPs are 40nm and 60nm. PVK/SiO₂ NPs compound systems with different sizes and with different ratios of mass fraction are obtained. Photoluminescence spectra are employed to research the optical properties of PVK molecules and PVK/SiO₂ NPs compound system. In compound system, the process of interface energy transfer between PVK and SiO₂ NPs are observed. The mainly energy transfer form is nonradiative resonance transfer.

Abstract: We report on photoluminescence (PL) properties of europium (Eu) and ytterbium (Yb) co-doped silicon oxide films with different Si excess. After annealing the films in N₂, strong PL were observed from Eu and Yb³⁺ ions and their intensities are correlated. The PL intensity of Eu is mainly from 3+ for no and relatively low temperature anneals (<900 ^°C) while the Eu²⁺ emission is dominating for annealing at 1000 ^°C or above in the co-doped Si-rich oxide films. Transmission electron microscopy shows amorphous (Eu, Yb, Si, O)-containing precipitates in the Si-rich oxide during 1000-1200 ^°C annealing and these precipitates are considered to be responsible for the Eu²⁺-related luminescence.

Abstract: With the actual case of isolation system design and noise control of roots blower room of a pharmaceutical factory in Shenyang taken into consideration, the overall computation was done on the basis of multi-vibration noise source. The vibration energy of equipments and noise propagation were analyzed both qualitatively and quantitatively with the spectral characteristics of vibration and wideband noise taken into account. Furthermore, the acoustic environment in the blower room was improved and the noise emission of the factory got down to the standard after the vibration isolation and noise reduction measures were applied. This work has important guiding significance and reference value for the projects on vibration isolation and noise control in the future.

Abstract: The momentum transfer by a planar wave impinging upon a rigid, free-standing plate in water, a largely incompressible medium, is well understood [1]. Kambouchev et al. [2] extended the results of Taylor [1] to include the nonlinear effects of compressibility whilst Hutchinson [3] has recently addressed the issues of energy and momentum transfer to a rigid, free-standing plate. In this paper, key conclusions from the aforementioned studies are critically re-examined in the context of a `fully-clamped' elastic plate. The dynamic response of an elastic plate is represented by an equivalent single-degree-of-freedom (SDOF) system. A numerical method based on a Lagrangian formulation of the Euler equations of compressible flow and conventional shock-capturing techniques, similar to that employed in [2, 3], were employed to solve numerically the interaction between the air blast wave and elastic plate. Particular emphasis is placed on elucidating the energy and momentum transfer to a `fully-clamped' elastic plate compared to its rigid, free-standing counterpart, and on whether enhancement in the beneficial effects of FSI as a result of fluid compressibility remains and to what extent.

Abstract: Understanding the mechanism of visible luminescence enhancement from rare earth doped glasses containing metallic nanoparticles (NPs) is the challenging issue. The photoluminescence (PL) spectra of Er³⁺: Au-doped tellurite glass is investigated for different concentration of gold NPs. A series of glasses with composition (70-x) TeO₂ -30 ZnO-0.5 Er₂O₃ x Au where x = (0.1, 0.3, 0.5 mol%) are prepared by melt-quenching method. The thermal parameters such as the glass transition (T_g), crystallization temperature (T_c) and melting temperature (T_m) are determined using DTA thermogram. PL spectra exhibit two distinct peaks at 493nm and 550nm which are assigned to the ²H_11/2-⁴I_15/2 and ⁴S_3/2-⁴I_15/2 transition respectively. The influence of gold NPs in enhancing the luminescence intensity under the 360nm excitation wavelength is observed understood.

Abstract: The paper presents research on use of magnetostrictive cores for the recovery of energy from vibrations and its use to power low-power electronics. To achieve this goal a test stand was constructed to generate and to receive the vibrations in the measurement system at the same time. Selection of an appropriate magnetomechanical parameters of the system was an important element influencing end results. The most important were values of the prestress and magnetising field for actuators and harvesters. As a result of the investigation the device operating in a wide frequency range (up to 40 KHz) and a system for energy transportation through mechanical vibrations were developed. Moreover it was shown that the proposed solution allow information transfer in a short bursts over the same system as energy transfer.

Abstract: Hydrogen is the most potential clean energy in the twenty-first century and can be obtained by the electrolysis of water. As a secondary energy, its production would be restricted by large amount of energy consumption and low efficiency. It is advantageous if an electrolyser can be simply and efficiently coupled to a renewable source of electrical energy. In this paper, it investigated the optimal way to maximize the transference of energy from a photovoltaic (PV) array directly coupled to a polymer electrolyte membrane (PEM) electrolyser in a photovoltaic-electrolyte hydrogen generation system (PV hydrogen system). The pivotal strategy is to find the series parallel combination of the PV cells and electrolyser stacks, which produces the highest energy transfer efficiency. The optimal configuration is a PV array consisted of three parallel connected PV cells directly coupled to a PEM electrolyser consisted of twelve series-connected electrolyser stacks with a day energy transfer efficiency of 99.52%. Comparisons between direct coupling systems and traditional ones have been presented. The result shows that direct coupling technology is feasible to improve the energy transfer efficiency in a PV hydrogen system.

Abstract: Luminescence of trivalent lanthanide ions (Ln³⁺) doped glasses is influenced by many factors. The emission enhancement of Ln³⁺ can be achieved either through an external approach or an internal adjustment. The external approaches mainly include application of metal nanoparticles, which changes the local structure, local filed and interaction with active ions. In this work, efforts to obtain luminescence enhancement in Ln³⁺ through introducing noble metals are reviewed. The merits of different processes are concluded.

Abstract: Single-phase Ba₅(PO₄)₃Cl:Ce³⁺,Tb³⁺ (BPCl:Ce³⁺,Tb³⁺) samples have been synthesized via solid-state reaction method. The phase structure and luminescence properties are characterized using powder X-ray diffraction (XRD), photoluminescence excitation and emission spectra. Effective energy transfer occurs from Ce³⁺ to Tb³⁺ due to the observed spectral overlap between the emission band of Ce³⁺ and the excitation band of Tb³⁺. Ce³⁺/Tb³⁺-codoped Ba₅(PO₄)₃Cl shows more intense yellowish-green light compared to that of Tb³⁺-doped sample under UV light excitation.

Abstract: With the asymmetric Schiff-base zinc complex ZnL (H₂L = N-(5-bromo-3-methoxysalicylidene)-N'-(5-(4-cyanophenyl)-3-methoxysalicylidene) phenylene-1,2-diamine) as the precursor, a series of heterobinuclear Zn-Ln complexes [ZnLnL(NO₃)₃(CH₃CN)] (Ln = Nd, 1; Ln = Yb, 2; Ln = Er, 3; Ln = Gd, 4) are synthesized by the further reaction with Ln (NO₃)₃·6H₂O, and characterized by FT-IR, FAB-MS and elementary analysis. Photophysical studies of these complexes show that the strong and characteristic NIR luminescence of Nd³⁺, Yb³⁺and Er³⁺ with emissive lifetimes in the microsecond range has been sensitized from the excited state of the asymmetric Schiff-base ligand due to effective intramolecular energy transfer.