Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 4

gain Related Abstracts

4 Long Wavelength GaInNAs Based Hot Electron Light Emission VCSOAs

Authors: Faten Adel Ismael Chaqmaqchee


Optical, electrical and optical-electrical characterisations of surface light emitting VCSOAs devices are reported. The hot electron light emitting and lasing in semiconductor hetero-structure vertical cavity semiconductor optical amplifier (HELLISH VCSOA) device is a surface emitter based on longitudinal injection of electron and hole pairs in their respective channels. Ga0.35In0.65N0.02As0.08/GaAs was used as an active material for operation in the 1.3 μm window of the optical communications. The device has undoped Distributed Bragg Reflectors (DBRs) and the current is injected longitudinally, directly into the active layers and does not involve DBRs. Therefore, problems associated with refractive index contrast and current injection through the DBR layers, which are common with the doped DBRs in conventional VCSOAs, are avoided. The highest gain of around 4 dB is obtained for the 1300 nm wavelength operation.

Keywords: Luminescence, HELLISH, VCSOA, GaInNAs, gain

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3 Evaluation of Short-Term Load Forecasting Techniques Applied for Smart Micro-Grids

Authors: Xiaolei Hu, Enrico Ferrera, Riccardo Tomasi, Claudio Pastrone


Load Forecasting plays a key role in making today's and future's Smart Energy Grids sustainable and reliable. Accurate power consumption prediction allows utilities to organize in advance their resources or to execute Demand Response strategies more effectively, which enables several features such as higher sustainability, better quality of service, and affordable electricity tariffs. It is easy yet effective to apply Load Forecasting at larger geographic scale, i.e. Smart Micro Grids, wherein the lower available grid flexibility makes accurate prediction more critical in Demand Response applications. This paper analyses the application of short-term load forecasting in a concrete scenario, proposed within the EU-funded GreenCom project, which collect load data from single loads and households belonging to a Smart Micro Grid. Three short-term load forecasting techniques, i.e. linear regression, artificial neural networks, and radial basis function network, are considered, compared, and evaluated through absolute forecast errors and training time. The influence of weather conditions in Load Forecasting is also evaluated. A new definition of Gain is introduced in this paper, which innovatively serves as an indicator of short-term prediction capabilities of time spam consistency. Two models, 24- and 1-hour-ahead forecasting, are built to comprehensively compare these three techniques.

Keywords: Artificial Neural Networks, Linear Regression, gain, short-term load forecasting, radial basis function network, smart micro grid

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2 Design of H-Shape X-band Application Electrically Small Antenna

Authors: Riki H. Patel, Trushit Upadhyaya, Arpan H. Desai


This paper presents a new small electrically antenna rectangular X- band micro-strip patch antenna loaded with material Rogers RT/duroid 5870 (tm). The present discussion focuses on small Electrically antenna which are electrically small compared to wave length the performance of electrically small antenna are closely related to their electrical size, the gain can be increased to maintain the efficiency of the radiator. Basically micro-strip Patch antennas have been used in satellite communications and for their good characteristics such as lightness, low cost, and so on. Here in the design H- shape folded dipole, which increase the band width of the antenna.

Keywords: Antenna, feed, gain, electrically small antennas, X-band application, micro-strip patch, frequency antenna

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1 Increasing of Gain in Unstable Thin Disk Resonator

Authors: M. Asl. Dehghan, M. H. Daemi, S. Radmard, S. H. Nabavi


Thin disk lasers are engineered for efficient thermal cooling and exhibit superior performance for this task. However the disk thickness and large pumped area make the use of this gain format in a resonator difficult when constructing a single-mode laser. Choosing an unstable resonator design is beneficial for this purpose. On the other hand, the low gain medium restricts the application of unstable resonators to low magnifications and therefore to a poor beam quality. A promising idea to enable the application of unstable resonators to wide aperture, low gain lasers is to couple a fraction of the out coupled radiation back into the resonator. The output coupling gets dependent on the ratio of the back reflection and can be adjusted independently from the magnification. The excitation of the converging wave can be done by the use of an external reflector. The resonator performance is numerically predicted. First of all the threshold condition of linear, V and 2V shape resonator is investigated. Results show that the maximum magnification is 1.066 that is very low for high quality purposes. Inserting an additional reflector covers the low gain. The reflectivity and the related magnification of a 350 micron Yb:YAG disk are calculated. The theoretical model was based on the coupled Kirchhoff integrals and solved numerically by the Fox and Li algorithm. Results show that with back reflection mechanism in combination with increasing the number of beam incidents on disk, high gain and high magnification can occur.

Keywords: gain, unstable resonators, thin disk lasers, external reflector

Procedia PDF Downloads 283