Numerical Experiment of Combined Infrared and Ultraviolet Radiation Remote Sensing to Determine the Profile and Total Content of Atmospheric Ozone

A new remote sensing method is described to determine the vertical distribution and total content of atmospheric ozone. The method combines surface infrared, satellite infrared and ultraviolet channels. The width of the infrared channels is 0.01 cm-1, less than Lorentz half-width at the earth's surface, rather than the present width, because these channels can obtain information about variations in the ozone profile below the profile main-peak. The numerical experiments show that the method has a satisfactory precision in determining total ozone content, just about I percent error, and vertical distribution from the earth to 65 km space. In addition, some semi-analysis functions lor calculating backscattered ultraviolet and a relaxation equation are described in this paper.

Comparative Study of Micro and Nano Size WO3/E44 Epoxy Composite as Gamma Radiation Shielding Using MCNP and Experiment

The radiation shielding characteristics of 50wt% WO3/E44 epoxy composite in various gamma energies from 80 keV to 1.33 MeV are investigated via the MCNP code. Thus two scales are considered for WOa filler particles： micro and nano with sizes of i #m and 5Onto, respectively. The simulation results show that W03 nano particles exhibit a larger increase in linear attenuation coefficient in comparison with micro size particles. Finally, validation of simulation results with the published experimental data shows a good agreement.

Experimental study on terahertz radiation

In this letter, we describe a coherent subpicosecond terahertz (THz) spectroscopy system based on non-resonant optical rectification for the generation of THz radiation. We studied the two-photon absorption (TPA) of ZnTe induced by femtosecond laser pulses via THz generation, and its influence on the generation of THz radiation. Experimental results demonstrated that the intensity of pump beam against TPA must be traded off to get an optimum generation of THz radiation. As an example, we measured absorption spectrum of water vapor by time-domain spectroscopy (TDS) in the frequency range from 0.5 to 2.5 THz with a high overall accuracy.

Experimental measurement of radiation dose in a dedicated breast CT system

Radiation dose is an important performance indicator of a dedicated breast CT（DBCT）.In this paper,the method of putting thermoluminescent dosimeters（TLD） into a breast shaped PMMA phantom to study the dose distribution in breasts was improved by using smaller TLDs and a new half-ellipsoid PMMA phantom.Then the weighted CT dose index（CTDI_w） was introduced to average glandular assessment in DBCT for the first time and two measurement modes were proposed for different sizes of breasts.The dose deviations caused by using cylindrical phantoms were simulated using the Monte Carlo method and a set of correction factors were calculated.The results of the confirmatory measurement with a cylindrical phantom（11 cm/8 cm） show that CTDI_w gives a relatively conservative overestimate of the average glandular dose comparing to the results of Monte Carlo simulation and TLDs measurement.But with better practicability and stability,the CTDI_w is suitable for dose evaluations in daily clinical practice.Both of the TLDs and CTDI_w measurements demonstrate that the radiation dose of our DBCT system is lower than conventional two-view mammography.

Measuring boundary-layer height under clear and cloudy conditions using three instruments

Boundary-layer height （BLH） under clear, altostratus and low stratus cloud conditions were measured by GPS sounding, wind profiler radar, and micro-pulse lidar during the atmospheric radiation measurement experiment from Sep. to Dec. 2008 in Shouxian, Anhui, China. Results showed that during daytime or nighttime, regardless of cloud conditions, the GPS sounding was the most accurate method for measuring BLH. Unfortunately, because of the long time gap between launchings, sounding data did not capture the diurnal evolution of the BLH. Thus, wind profile radar emerged as a promising instrument for direct and continuous measurement of the mixing height during the daytime, accurately determining BLH using the structure parameter of the electromagnetic refractive index. However, during nighttime, radar was limited by weak signal extraction and did not work well for determining the BLH of the stable boundary layer, often recording the BLH of the residual layer. While micro-pulse lidar recorded the evolution of BLH, it overestimated the BLH of the stable boundary layer. This method also failed to work under cloudy conditions because of the influence of water vapor. Future work needs to develop a method to determine BLH that combines the complimentary features of all three algorithms.