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Piezoelectric coupling in energy-harvesting fluttering flexible plates : linear stability analysis and conversion efficiency  [PDF]
Olivier Doare,Sebastien Michelin
Physics , 2011, DOI: 10.1016/j.jfluidstructs.2011.04.008
Abstract: This paper investigates the energy harvested from the flutter of a plate in an axial flow by making use of piezoelectric materials. The equations for fully-coupled linear dynamics of the fluid-solid and electrical systems are derived. The continuous limit is then considered, when the characteristic length of the plate's deformations is large compared to the piezoelectric patches' length. The linear stability analysis of the coupled system is addressed from both a local and global point of view. Piezoelectric energy harvesting adds rigidity and damping on the motion of the flexible plate, and destabilization by dissipation is observed for negative energy waves propagating in the medium. This result is confirmed in the global analysis of fluttering modes of a finite-length plate. It is finally observed that waves or modes destabilized by piezoelectric coupling maximize the energy conversion efficiency.
New approach to enhance the up-conversion efficiency in the Ho3+-Yb3+ co-doped system
New approach to enhance the up—conversion efficiency in the Ho^3+—Yb^3+ co—doped system

Xiao Si-Guo,Yang Xiao-Liang,Liu Zheng-Wei,

中国物理 B , 2002,
Abstract: We investigate the up-conversion luminescence spectra of Ho3+-Yb3+ co-doped materials excited with two types of laser. It is found that the efficiency of green emission (5S2-5I8) can be enhanced by restraining the transition of 5S2-5I7 since the two types of radiation both start on the 5S2 level. We propose an important approach to enhance an expected up-conversion emission.
Solar cells conversion efficiency enhancement techniques
Optica Applicata , 2007,
Abstract: In order to enhance the conversion efficiency of GaAs p-i-n solar cells GaAs/AlxGa1–xAs QW within intrinsic region or gradation of Al fraction of AlxGa1–xAs emitter and base region were applied. The influence of AlAs Bragg reflectors on the performance of MQWSC was studied theoretically by using SimWindows software.
Adaptive Critic Based Neuro-Fuzzy Tracker for Improving Conversion Efficiency in PV Solar Cells  [cached]
Halimeh Rashidi,Saeed Niazi,Jamshid Khorshidi
Research Journal of Applied Sciences, Engineering and Technology , 2012,
Abstract: The output power of photovoltaic systems is directly related to the amount of solar energy collected by the system and it is therefore necessary to track the sun’s position with high accuracy. This study proposes multi-agent adaptive critic based nero fuzzy solar tracking system dedicated to PV panels. The proposed tracker ensures the optimal conversion of solar energy into electricity by properly adjusting the PV panels according to the position of the sun. To evaluate the usefulness of the proposed method, some computer simulations are performed and compared with fuzzy PD controller. Obtained results show the proposed control strategy is very robust, flexible and could be used to get the desired performance levels. The response time is also very fast. Simulation results that have been compared with fuzzy PD controller show that our method has the better control performance than fuzzy PD controller.
Optimization of Photoelectrode for Flexible Dye-sensitized Solar Cell and Preliminary Study of Tandem Cell
LIU Feng-Juan, SHAO Jing-Zhen, DONG Wei-Wei, DENG Zan-Hong, WANG Shi-Mao, FANG Xiao-Dong
无机材料学报 , 2013, DOI: 10.3724/sp.j.1077.2013.12386
Abstract: Based on the preparation of flexible dye-sensitized solar cells (DSC) by cold isostatic pressing method, optimization of the paste and tandem DSC were investigated. The results presented that hydrothermal treatment of P25 paste could improve the stability of the paste and the efficiency of DSC obviously. Proper amount of 200 nm TiO2 particles was added to the P25 paste to enhance light scattering of photoelectrode. The highest conversion efficiency of 3.11% was obtained at the 4:1 ratio of P25 to 200 nm TiO2. Subsequently, N719 and N749 double-layer tandem DSC were studied. The results show that the efficiency of the double-layer tandem DSC is higher than that of N749 totally sensitized DSC but lower than that of N719 totally sensitized DSC. This may be caused by that thicker photoelectrode hampers the electronic transmission and dyes contact impacts the purity of dyes. The thickness of photoelectrode and cell structure need to be optimized.
Efficiency of Energy Conversion in Thermoelectric Nanojunctions  [PDF]
Yu-Shen Liu,Yi-Ren Chen,Yu-Chang Chen
Physics , 2009, DOI: 10.1021/nn900986r
Abstract: Using first-principles approaches, this study investigated the efficiency of energy conversion in nanojunctions, described by the thermoelectric figure of merit $ZT$. We obtained the qualitative and quantitative descriptions for the dependence of $ZT$ on temperatures and lengths. A characteristic temperature: $T_{0}= \sqrt{\beta/\gamma(l)}$ was observed. When $T\ll T_{0}$, $ZT\propto T^{2}$. When $T\gg T_{0}$, $ZT$ tends to a saturation value. The dependence of $ZT$ on the wire length for the metallic atomic chains is opposite to that for the insulating molecules: for aluminum atomic (conducting) wires, the saturation value of $ZT$ increases as the length increases; while for alkanethiol (insulating) chains, the saturation value of $ZT$ decreases as the length increases. $ZT$ can also be enhanced by choosing low-elasticity bridging materials or creating poor thermal contacts in nanojunctions. The results of this study may be of interest to research attempting to increase the efficiency of energy conversion in nano thermoelectric devices.
Semiconductor-Optical-Amplifier-Based Inverted and Non-Inverted Wavelength Conversion at 40Gb/s Using a Detuning Optical Bandpass Filter
Semiconductor-Optical-Amplifier-Based Inverted and Non-Inverted Wavelength Conversion at 40 Gb/s Using a Detuning Optical Bandpass Filter

DONG Jian-Ji,ZHANG Xin-Liang,HUANG De-Xiu,

中国物理快报 , 2007,
Abstract: We experimentally demonstrate 40Gb/s semiconductor-optical-amplifier-based tunable wavelength conversion (WC) using a detuning optical bandpass filter. Both inverted and non-inverted WCs are obtained by shifting the filter centralwavelength with respect to the probe wavelength. When the filter is red shifted by 0.4nm or blue shifted by 0.3nm, the WC is non-inverted. However, when the filter is blue shifted by 0.1nm, the WC is inverted. It is experimentally demonstrated that the WC has a tunable range covering the C-band.
Investigation on inverted and non-inverted wavelength conversion based on transient cross phase modulation of semiconductor optical amplifier

Dong Jian-Ji,Zhang Xin-Liang,Fu Song-Nian,P Shum,Huang De-Xiu,

物理学报 , 2007,
Abstract: All-optical wavelength conversion based on transient cross phase modulation of semiconductor optical amplifier (SOA) is a promising approach to achieve high-speed all-optical signal processing. We experimentally demonstrate inverted and non-inverted wavelength conversion (WC) based on single SOA and an optical bandpass filter with 0.4 nm bandwidth. When the central wavelength of the following filter is blue shifted by 0.25 nm or red shifted by 0.05 nm with respect to the wavelength of probe signal, the WC is inverted. When the filter detuning is blue shifted 0.29 nm or red shifted 0.25 nm, the WC is non-inverted. The polarity evolution from inverted WC to non-inverted WC is also presented with numerical simulation. The obtained results are in good agreement with the experiment.
Inverted Hierarchy of Neutrino Masses Disfavored by Supernova 1987A  [PDF]
Hisakazu Minakata,Hiroshi Nunokawa
Physics , 2000, DOI: 10.1016/S0370-2693(01)00254-4
Abstract: We discuss the flavor conversion of supernova neutrinos in the three-flavor mixing scheme of neutrinos. We point out that by neutrino observation from supernova one can discriminate the inverted hierarchy of neutrino masses from the normal one if s_{13}^2 \gsim a few \times 10^{-4}, irrespective of which oscillation solution to the solar neutrino problem is realized in nature. We perform an analysis of data of SN1987A and obtain a strong indication that the inverted mass hierarchy is disfavored unless s_{13}^2 \lsim a few \times 10^{-4}.
Simultaneous Inverted and Non-inverted Wavelength Conversion Based on Cross Polarization Modulation in Semiconductor Optical Amplifier

Zhou Yunfeng,Zhang Junyi,Wu Jian,Lin Jintong,

光子学报 , 2006,
Abstract: Based on cross polarization modulation effect in semiconductor optical amplifier (SOA), wavelength conversion was analyzed theoretically.Which shows that wavelength conversion can be realized. Both inverted and non-inverted wavelength conversions of 10 Gb/s RZ signal were experimentally achieved simultaneously for the first time, with 8.1 dB and 6.9 dB output extinction ratio respectively.
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