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Initial results from the first airborne campaign to evaluate P-band reflectometry for soil moisture remote sensing are presented. P-band radiation has a penetration depth of 10–20 cm, compared to around 5 cm for L-band. This offers the possibility of measuring Root-Zone Soil Moisture (RZSM), a capability that does not presently exist in spaceborne remote sensing. Signals of Opportunity Airborne Demonstrator...
Advanced antenna arrays were designed for NASA's EcoSAR airborne radar instrument. EcoSAR is a beamforming synthetic aperture radar instrument designed to make polarimetric and "single pass" interferometric measurements of Earth surface parameters. EcoSAR's operational requirements of a 435MHz center frequency with up to 200MHz bandwidth, dual polarization, high cross-polarization isolation...
Advanced Digital Beamforming (DBF) Synthetic Aperture Radar (SAR) technology is an area of research and development pursued at the NASA Goddard Space Flight Center (GSFC). Advanced SAR architectures enhances radar performance and opens a new set of capabilities in radar remote sensing. DBSAR-2 and EcoSAR are two state-of-the-art radar systems recently developed and tested. These new instruments employ...
This paper is oriented towards comparison of measurement methods for iodine absorption cells quality evaluation. Traditionally used method of laser induced fluorescence with evaluation of Stern-Volmer coefficients and method of measurement of absolute frequency shifts of hyperfine spectras have several limitations and sensitivity limits. Due to this reason an alternative technique of hyperfine spectra...
In this paper, we propose an approach for demand side energy scheduling to reduce residential users' energy cost by smoothing the energy consumption. The energy consumption of each residential user is smoothed in time horizon to reach the goal that the energy consumption of a large number of users is smoothed as well. Both the energy cost and peak-to-average ratio are reduced through our proposed...
A compact fiber torsion sensor, in which a short section of polarization-maintaining (PM) fiber stub containing a normal straight fiber Bragg grating (FBG) is spliced to another single-mode fiber without any lateral offset, is proposed and experimentally demonstrated. Two well-defined resonances (orthogonal-polarimetric FBG core-modes) with ∼0.5 nm wavelength separation have been achieved in reflection...
We report on the frequency stabilization of an infrared (IR) laser emitting at 1.5 μm onto molecular iodine hyperfine transitions at 514 nm. Third harmonic generation process based on Periodically Poled Lithium Niobate non linear crystals (PPLN) is used to link the IR emission to the green region. We have developed and tested a compact experimental setup using a multi-pass iodine cell in order to...
In order to make an accurate prediction of the greenhouse environment parameters, this paper proposes a controlling method for greenhouse prediction. Targeting that the former greenhouse model is not precise enough, and that the model parameters are difficult to determine, the paper firstly makes an analysis of the technical difficulties, and then proposes a prediction method based on dynamic matrix...
We report on phase locking of two infrared (IR) lasers separated by 500 nm, using independent harmonic generation processes in periodically poled LiNbO3 (PPLN) crystals.
This paper describes objectives and recent progress on the development of the EcoSAR, a new P-band airborne radar instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. These measurements support science requirements for the study of the carbon cycle and its relationship to climate change...
The physics of the transport of large currents of fast (relativistic) electrons in dense matter underpins many topics in high intensity laser-solid interactions, including warm dense matter, ion acceleration and the fast ignition approach to inertial confinement fusion. The propagation of fast electrons within the target is subject to transport instabilities (e.g. resistive instabilities) which give...
This paper outlines the design strategy for the University of Johannesburg's (UJ's) hybrid vehicle entry into the South African Solar Challenge (SASC) 2010. The SASC is a biennial event focused on alternative energies and showcasing various automotive technologies. The SASC is broken up into different classes; UJ entered in the Greenfleet Technology class. This paper presents the design principles...
Application areas like global sensor networks and data stream processing involve the on-line processing of large amounts of data in an overlay network of operators on top of the Internet infrastructure. Trying to fulfill QoS guarantees in such networks is a challenging task that should be realized under the requirement for optimal usage of common resources in the network. Therefore in this paper,...
We have demonstrated an intense plasma-based THz source using ~5 TW femtosecond laser pulses to irradiate solid targets. The energy of a single THz pulse emitted in the laser specular direction increases with the laser energy. The maximum THz energy can be as high as tens μJ/sr. The polarization of the THz pulse is measured to be linear.
Summary form only given. The effects of preplasma on lateral fast electron transport at front target surface irradiated by ultraintense (>1018 W/cm2) laser pulses are experimentally investigated. A spherically bent quartz crystal is used to record two-dimensional spatially resolved Kα x-ray emission resulting from fast electron transport. A large (~ 600μm in diameter) annular Kα halo structure...
This paper presents two comprehensive models of DC subway traction system to simulate the starting-up process using Matlab/simulink. One is DC motor driven, the other is AC motor driven. The model includes substation rectifiers, the track and the different driven subway trains. The objective of the model is to study the short circuit faults and the train starting current. Analysis and conclusion of...
This paper presents a simulation and protection algorithm of DDL in DC traction system based on MATLAB/Simulink. With the introduction of the operation of DC traction system, this paper developed different models and implemented the simulation and test separately for different feeding arrangement and operation condition of DC power supply system, analyzed the characteristics of the typical train starting...
We have demonstrated an intense plasma-based THz source using ~5 TW femtosecond laser pulses to irradiate solid targets. The energy of a single THz pulse emitted in the laser specular direction increases with the laser energy. The maximum THz energy can be as high as tens μJ/sr. The polarization of the THz pulse is measured to be linear.
This paper presents a new current selective trip protection algorithm which is based on the current changes on the same end of line. The new algorithm can reduce the communication of transmission line pressure and reduce the length of the signal delay to the protection of the impact. With the introduction of the new algorithm, the typical AC power ring line for DC railway system based on PSCAD is...
This paper presents a simulation of regenerative braking in DC railway system. The model of DC locomotive with DC-AC PWM convertor has been proposed which is according to Beijing No.5 Line Subway train. Based on the data of a practical train, this paper has made calculation of regenerative braking currents. The calculation has verified the correctness of the simulation model.
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