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81.
This paper addresses the assessment of power quality (PQ) in 3-Ф grid connected photovoltaic (PV) system that consists of single and dual stage power extraction circuits. The single stage circuit comprises of Z-source inverter (ZSI) controlled by space vector pulse width modulation (SVPWM), while dual stage is traditional boost based voltage source inverter controlled by sinusoidal pulse width modulation. The PQ of signals in both the circuits is analyzed during transient variations like solar intensity and load conditions, with/without use of hybrid filter. The simulation and experimental results suggest an improved smooth sinusoidal waveform available at PCC in case of ZSI based circuit using hybrid filter, if power quality improvement is of prime importance with both linear and nonlinear load connected in the system. 相似文献
82.
解释了膨胀聚苯乙烯泡沫板(EPS板)、石墨模塑聚苯乙烯泡沫塑料板(SEPS板)和热固性改性聚苯乙烯泡沫塑料板(热固性EPS板)的定义,对6个不同厂家生产的EPS板、SEPS板、热固性EPS板的主要物理性能进行了研究,得出了一些有实用价值的结论。 相似文献
83.
《Carbon》2014
Titanium dioxide nanoparticles prepared in situ by sol–gel method were supported on a spherical activated carbon to prepare TiO2/AC hybrid photocatalysts for the oxidation of gaseous organic compounds. Additionally, a granular activated carbon was studied for comparison purposes. In both types of TiO2/AC composites the effect of different variables (i.e., the thermal treatment conditions used during the preparation of these materials) and the UV-light wavelength used during photocatalytic oxidation were analyzed. The prepared materials were deeply characterized (by gas adsorption, TGA, XRD, SEM and photocatalytic propene oxidation). The obtained results show that the carbon support has an important effect on the properties of the deposited TiO2 and, therefore, on the photocatalytic activity of the resulting TiO2/AC composites. Thus, the hybrid materials prepared over the spherical activated carbon show better results than those prepared over the granular one; a good TiO2 coverage with a high crystallinity of the deposited titanium dioxide, which just needs an air oxidation treatment at low-moderate temperature (350–375 °C) to present high photoactivity, without the need of additional inert atmosphere treatments. Additionally, these materials are more active at 365 nm than at 257.7 nm UV radiation, opening the possibility of using solar light for this application. 相似文献
84.
《Carbon》2015
We present a facile and efficient route to introduce in-plane nanopores on the graphene sheets by activation of graphene aerogel (GA) with phosphoric acid (H3PO4). Results from N2 adsorption and TEM images showed that H3PO4 activation created mesopores with pore size of 2–8 nm on the graphene sheets. With such nanopores on graphene sheets, the activated GA exhibits a specific capacitance of 204 F g−1, enhanced rate capability (69% capacitance retention from 0.2 to 30 A g−1), reduced equivalent series resistance (3.8 mΩ) and shortened time constant (0.73 s) when comparing with the hydrothermally-derived pristine GA and thermally annealed GA in the absent of H3PO4. The excellent capacitive properties demonstrate that introduction of nanopores on GA by H3PO4 activation not only provides large ion-accessible surface area for efficient charge storage, but also promotes the kinetics of electrolyte across the graphene two-dimensional planes. 相似文献
85.
By electrospraying solvent dispersed carbon nanotubes (CNTs) with a binder onto carbon fibre (CF), hybrid structures, with an end aim to improve interfacial bonding in composites, were formed. The electrospray parameters controlling the modification of the CNT morphologies were studied. High-speed camera observations found applied voltage was critical for determining spray mode development. Electric field simulations revealed a concentrated electric field region around each fibre. Both voltage and distance played an important role in determining the CNT morphology by mediating anchoring strength and electric field force. The forming mechanism investigation of different surface morphologies suggested that binder with appropriate wetness gives freedom to the CNTs, allowing them to orientate radially from the CF surface. Linear density (LD) measurements and thermogravimetric analysis revealed that a 10 min coating increased the LD of a single CF filament by up to 31.7% while a 1 h treatment increased fibre bundle mass by 1%. 相似文献
86.
We have demonstrated continuous wave (CW) laser operation of Nd:YNbO4 crystal at 1066 nm for the first time. A maximum output power of 1.12 W with the incident power of 5.0 W is successfully achieved corresponding to an optical-to-optical conversion efficiency of 22.4% and a slope efficiency of 24.0%. The large absorption cross section (8.7 × 10−20 cm2) and wide absorption band (6 nm) at around 808 nm indicates the good pumping efficiency by laser diodes (LD). The small emission cross section (29 × 10−20 cm2) and relative long lifetime of the 4F3/2 → 4I11/2 transition indicates good energy storage capacity of Nd:YNbO4. Moreover, the raw materials of Nd:YNbO4 are stable, thus, it can grow high-quality and large-size by Czochralski (CZ) method. Therefore the Nd:YNbO4 crystal is a potentially new laser material suitable for LD pumping. 相似文献
87.
太原市博物馆为不规则的椭圆倒锥体,致使其外墙幕墙工程施工难度大。本工程采用了敞缝干挂铝板—玻璃肋幕墙方法施工,有效地解决了开缝铝板幕墙施工中的难点问题,取得了良好的经济效益和社会效益。 相似文献
88.
89.
以某建筑住宅的外墙保温施工为例,在了解该工程施工背景概况的基础上,深入研讨了外墙保温施工的方法,着重对基层墙面清理、石墨聚苯板粘贴、固定件安装等技术作了阐述,为同类工程施工积累了经验。 相似文献
90.
Selective oxidation of alkenes with air to corresponding epoxides was performed over simple ion-exchanged Co-MOR and Co-5A. Among all transition metal ions-exchanged M-zeolites, both Co-MOR and Co-5A exhibited the highest activity at 363 K. Notably, for the epoxidation of styrene, α-pinene, α-methyl styrene and cyclooctene, Co-MOR obtained higher conversions than Co-5A, in agreement with the difference of pore sizes of both zeolitic materials. Recycling and control tests showed high durability of Co-MOR as a heterogeneous catalyst in our catalytic system. 相似文献