Angular variation of absorption and thermal emission enhancement from the two dimensional photonic crystals

Photonic crystal structures and their applications are an active growing research area in the scientific community. The photonic crystals can have a complete bandgap for proper choice of the structure and dielectric contrast. Photonic crystal structures are very useful in many areas such as photovoltaic devices, infrared sources and optic fibers. The photonic crystal structures have been used in the thermal photovoltaic devices and as a narrow band infrared emitter. In this thesis we investigate the angular variation of absorption and thermal emission from the two-dimensional metallic and metal-dielectric photonic crystal structures by using rigorous scattering matrix method. We found that the thermal emission of these photonic crystals at different wavelengths is redistributed into different emission angles. The photon emission are partially suppressed at long wavelengths and enhanced at the shorter wavelength range. We utilized the surface plasmon models to describe the angular dependent absorption. The strong spectral variation of the thermal emission with angle should be accounted for the thermo-photovoltaic devices utilizing photonic crystals. We also propose a metallic photonic crystal for incandescent filaments. We simulated the tungsten photonic crystals and found that by using the photonic crystals it is possible to increase the lifetime and brightness of light bulbs. We also present results for metal-dielectric patches at infrared length scales and find absorption peaks can be tuned by the geometry of the patch

The Optimal Configuration and Their Strategic Analysis of Information System Security Technology Portfolios

Confronted with the increasingly severe information security problems, proper configuration of security technologies is critical to enhance the information systems performance. To solve the integrated linkage control problem based on attack detection, the security model including firewall, intrusion detection system (IDS) and vulnerability scan is analyzed by game theory. The analyses show that more IT portfolio will not bring better benefits, and more fixed vulnerabilities are not the better choice for the firm either. However, reasonable configuration of firewall will always reduce the firm’s expected loss. According to the Nash equilibrium of the model, technical parameters are configured to minimize the firm’s expected loss

Towards Efficient and Accurate Approximation: Tensor Decomposition Based on Randomized Block Krylov Iteration

Efficient and accurate low-rank approximation (LRA) methods are of great significance for large-scale data analysis. Randomized tensor decompositions have emerged as powerful tools to meet this need, but most existing methods perform poorly in the presence of noise interference. Inspired by the remarkable performance of randomized block Krylov iteration (rBKI) in reducing the effect of tail singular values, this work designs an rBKI-based Tucker decomposition (rBKI-TK) for accurate approximation, together with a hierarchical tensor ring decomposition based on rBKI-TK for efficient compression of large-scale data. Besides, the error bound between the deterministic LRA and the randomized LRA is studied. Numerical experiences demonstrate the efficiency, accuracy and scalability of the proposed methods in both data compression and denoising

Structures and photoelectron spectroscopy of Cu-n(BO2)(m) - (n, m=1, 2) clusters: Observation of hyperhalogen behavior

The electronic structures of CuBO2 −, Cu(BO2)2 −, Cu2(BO2)−, and Cu2(BO2)2 − clusters were investigated using photoelectron spectroscopy. The measured vertical and adiabatic detachment energies of these clusters revealed unusual properties of Cu(BO2)2 cluster. With an electron affinity of 5.07 eV which is larger than that of its BO2 superhalogen (4.46 eV) building-block, Cu(BO2)2 can be classified as a hyperhalogen. Density functional theory based calculations were carried out to identify the ground stategeometries and study the electronic structures of these clusters. Cu(BO2) and Cu(BO2)2 clusters were found to form chainlike structures in both neutral and anionic forms. Cu2(BO2) and Cu2(BO2)2 clusters, on the other hand, preferred a chainlike structure in the anionic form but a closed ringlike structure in the neutral form. Equally important, substantial differences between adiabatic detachment energies and electron affinities were found, demonstrating that correct interpretation of the experimental photoelectron spectroscopy data requires theoretical support not only in determining the ground stategeometry of neutral and anionic clusters, but also in identifying their low lying isomers

Evaluation of the Ecological Quality of the Taishan Region Based on Landsat Series of Satellite Images

The deterioration of ecological environment has seriously restricted regional sustainable development. Taishan region is one of the ecological protection and restoration of life community of mountains-rivers-forests-farmlands-lakes-grasslands in China. Its ecological quality changes are directly related to the overall layout of ecological restoration and protection projects. In this study, the Taishan region of China was taken as study area, and the grade change, spatial distribution, and spatial temporal fluctuation of the ecological environment quality were quantified. Based on the ENVI platform, the Landsat series of three images of the Taishan region in 2005, 2013, and 2017 serve as the data source, and the remote sensing ecological index model (RSEI) was used. According to the change characteristics of land use types, the driving factors of ecological environmental quality change were analyzed. The results showed that: (1) The area ratio of the ecological environment quality above the middle level was in order from large to small: 2005 (97.37%) > 2017 (91.46%) > 2013 (84.64%). (2) The overall quality of the ecological environment declined during the period of 2005-2013. (3) The overall change ranges from 2013 to 2017 are smaller than those from 2005 to 2013. The area of the deteriorating area decreased by 44.90%, and the area of the constant area and the area of the area that improved increased by 16.17% and 28.72%, respectively. During 2013-2017, the general trend is getting better and better. The improved areas were mainly concentrated in the main urban areas (Taishan District, Daiyue District), eastern Ningyang County, and western Xintai City. The research results can provide a scientific basis for the scientific evaluation of the ecological environment quality during the development and construction of the region, and have important value in the design and application of the ecological environment quality optimization path

Chemical composition of Chinese palm fruit and chemical properties of the oil extracts

The proximate composition, mineral concentration of fleshy mesocarp, palm meat (PM) and palm kernel (PK) of oil palm fruit (Elaeis guineensis S.L.Dura) produced in Hainan, China were investigated. The fatty acid composition, chemical properties and minor constituents of palm oil (PO) and palm kernel oil (PKO) were also studied. The crude fat of PM and PK were 68.09±3.57% and 49.36±2.61%, respectively. The PM and PK were found to be good sources of minerals. The acid value (AV) and free fatty acid (FFA) of PO extracted from fresh PM were much higher. If the fresh PM were heated at 100ºC for 30 min, the AV and % FFA could be reduced to 4.62±0.04 mgKOH/g and 2.72±0.002%, respectively. The major fatty acid of PO was palmitic acid 39.93±1.66% and that of PKO was lauric acid 48.01±0.69%. Tocopherol isomer (α-, (β+γ)- and δ-) contents in PO were 68.8±1.84, 22.8±0.54 and 11.8±0.12 mg/kg, respectively. The β-carotene content in PO was 901.5±11.95 mg/kg. The content of sterols in PO and PKO were 880.0±5.23 and 858.0±4.37 mg/kg, respectively. PO and PKO exhibited good chemical properties and could be used as edible oils and for industrial applications. There are almost no data about Chinese palm fruit now and this study systematically researched on it, which can provide useful information for Chinese oil palm industry.Key words: Chemical composition, palm fruit, palm oil, palm kernel oil, chemical properties