In this note, we establish a new characterization on g-frames in Hilbert C;-modules from the operator-theoretic point of view, with which we provide a correction to one result recently obtained by Yao(Yao X Y. Some pr...In this note, we establish a new characterization on g-frames in Hilbert C;-modules from the operator-theoretic point of view, with which we provide a correction to one result recently obtained by Yao(Yao X Y. Some properties of g-frames in Hilbert C;-modules（in Chinese）. Acta Math. Sinica, 2011, 54（1）: 1–8.).展开更多
The current study presents the characterization of three types of materials after exposure to solar UV radiation. The selection of the materials is related to socio-economic aspects and rural activities in the northwe...The current study presents the characterization of three types of materials after exposure to solar UV radiation. The selection of the materials is related to socio-economic aspects and rural activities in the northwest of Argentina (a.k.a. NOA). The objective was to establish a time parameter that allows estimating the durability of the materials according to their use. One of the materials is used as a protective cover (polyethylene film) of greenhouses, which are used for crop cultivation in the area. Another material is used in photovoltaic modules (PVMs), which are used to supply energy in isolated areas and the third material is sunscreen used by people that are exposed to UV radiation during rural activities. Degradation or deterioration of the materials was monitored using different spectroscopic assays: infrared was used to detect any structural changes in the material, X-rays were used for possible changes in the crystalline structure of the material, and spectral transmittance as this property is likely to be affected by changes in the structure of the material. The results showed that degradation of polyethylene seems to be related to the diminution in transparency and the loss of mechanical resistance with increasing exposure time. The decrease in transparency of one of the layers of a PVM caused a considerable decrease in the energy generated, whereas the sunscreens with a low sun protection factor (SPF) rapidly lost their protective properties and changed their photostability properties. Our results revealed a relationship between relative transmittance loss and exposure timse, which allows estimating the stability of different materials.展开更多
基金The NSF(11271148,11561057)of Chinathe NSF(20151BAB201007)of Jiangxi Provincethe Science and Technology Project(GJJ151061)of Jiangxi Education Department
文摘In this note, we establish a new characterization on g-frames in Hilbert C;-modules from the operator-theoretic point of view, with which we provide a correction to one result recently obtained by Yao(Yao X Y. Some properties of g-frames in Hilbert C;-modules（in Chinese）. Acta Math. Sinica, 2011, 54（1）: 1–8.).
文摘The current study presents the characterization of three types of materials after exposure to solar UV radiation. The selection of the materials is related to socio-economic aspects and rural activities in the northwest of Argentina (a.k.a. NOA). The objective was to establish a time parameter that allows estimating the durability of the materials according to their use. One of the materials is used as a protective cover (polyethylene film) of greenhouses, which are used for crop cultivation in the area. Another material is used in photovoltaic modules (PVMs), which are used to supply energy in isolated areas and the third material is sunscreen used by people that are exposed to UV radiation during rural activities. Degradation or deterioration of the materials was monitored using different spectroscopic assays: infrared was used to detect any structural changes in the material, X-rays were used for possible changes in the crystalline structure of the material, and spectral transmittance as this property is likely to be affected by changes in the structure of the material. The results showed that degradation of polyethylene seems to be related to the diminution in transparency and the loss of mechanical resistance with increasing exposure time. The decrease in transparency of one of the layers of a PVM caused a considerable decrease in the energy generated, whereas the sunscreens with a low sun protection factor (SPF) rapidly lost their protective properties and changed their photostability properties. Our results revealed a relationship between relative transmittance loss and exposure timse, which allows estimating the stability of different materials.
