Optomechanical Design and Application of Solar-Skylight Spectroradiometer

Using a solar radiometer is an effective approach for improving the remote sensing of solar irradiance distribution and atmospheric composition. Long-term development of a solar scanning radiometer enables frequent and reliable measurement of atmospheric parameters such as the water vapor column and aerosol optical properties. However, the discrete wavelength radiometer has encountered a bottleneck with respect to its insufficient spectral resolution and limited observation waveband, and it has been unable to satisfy the needs of refined and intelligent on-site experiments. This study proposes a solar-skylight spectroradiometer for obtaining visible and near-IR fine spectrum with two types of measurement: direct-sun irradiance and diffuse-sky radiance. The instrument adopts distributed control architecture composed of the ARM-Linux embedded platform and sensor networks. The detailed design of the measuring light-path, two-axis turntable, and master control system will be addressed in this study. To determine all coefficients needed to convert instrument outputs to physical quantities, integrating sphere and Langley extrapolation methods are introduced for diffuse-sky and direct-sun calibration, respectively. Finally, the agreement of experimental results between spectroradiometers and measuring benchmarks (DTF sun-photometer, microwave radiometer, and Combined Atmospheric Radiative Transfer simulation) verifies the feasibility of the spectroradiometer system, and the radiation information of feature wavelengths can be used to retrieve the characteristics of atmospheric optics.

Development of Asymmetric Low Pressure Reverse Osmosis-Surfactants Membrane: Effect of Surfactant Types and Concentration

The effect of surfactants that are cationic (Cetyl trimethylammonium bromide (CTAB)), anionic (Sodium Dodecyl Sulphate (SDS)) and non-ionic (Triton X-100) on performance, morphologies and molecular orientation of Polysulfone (PSF) low pressure reverse osmosis (LPRO) membrane were addressed. The experimental data showed that the increasing of 0.5 wt% in surfactant concentration produced higher pure water permeation (PWP) and flux. At 2.5 wt% of SDS, the LPRO membranes achieved the highest PWP of about 64.42 L/m2 × h while 3.0 wt% of CTAB demonstrated the highest flux of 55.28 L/m2 × h. Analysis from morphological results foundthat the optimal performance at 89.6 % rejection was produced by the membrane with 2 wt% SDS which is a good promoter for the fine morphological structures of the membrane, thus producing fine spectrum of molecular orientation factor.