Papers by Keyword: Source

Abstract: This work describes the development of a new post-implant crystal recovery technique in 4H-SiC using XeCl (l=308 nm) multiple laser pulses in the ns regime. Characterization was carried out through micro-Raman spectroscopy, Photoluminescence (PL), Transmission Electron Microscopy (TEM) and outcomes were than compared with 1h thermally annealed at 1650-1770-1750 °C P implanted samples (source implant) and P and Al implanted samples for 30 minutes at 1650 °C (source and body implants). Experimental results demonstrate that laser annealing enables crystal recovery in the energy density range between 0.50 and 0.60 J/cm². Unlike the results obtained with thermal annealing where stress up to 172 Mpa and high carbon vacancies (V_c) concentration is recorded, laser annealing provides almost stress free samples and much less defective crystal avoiding intra-bandgap carrier recombination. Implant was almost preserved except for step-bouncing and surface oxidation phenomena leading to surface roughening. However, the results of this work gives way to laser annealing process practicability for lattice damage recovery and dopant activation.

Abstract: This paper presents the results of studies of the composite metal radio-protective building material by method of atomic-force probe microscopy, before and after its irradiation with gamma rays of 661.7 keV and absorbed dose up to 2 MGy. Composite metal material is based on the filling of hematite iron ore concentrate and aluminum matrix. This composite material has high technical (physical and mechanical) and radio-protective proprieties. The composite is planned to be employed as a bearing structure at various nuclear facilities.

Abstract: Non-destructive testing (NDT) of thin-walled parts is being considered. This technique is based on registration of changes in thermal fields created by sources on internal defects of the material. Mathematical model calculating surface temperatures of the part in each time-step has been built. The deduced system has been transformed into matrix format by the finite elements method. Solution has been found by the finite difference method. Actual tests has been conducted registering changes in surface temperature of the plate with symmetrical and asymmetrical internal source position. The model has been fine-tuned based on comparison of actual tests’ results with numerical calculations.

Abstract: This paper analyzed the content, distribution and source of Cu in Jiaozhou Bay in 1982. Results showed that the Cu contents in surface waters were relatively low, and the pollution level of Cu in 1982 was very slight. The major Cu source in the southwest of the bay was overland runoff; while for the northeast ocean current was responsible. The input contents of overland runoff and ocean current ranged from 2.22-3.56 μg.L^-1 and 0.15-5.31μg.L^-1, respectively.

Abstract: This paper analyzed the content, distribution and source of Zn in Jiaozhou Bay in 1982. Results showed that the Zn contents in surface waters in April, June, July and October ranged from 1.75-167.71 μg.L^-1, 8.31-36.97 μg.L^-1, 7.05-12.18 μg.L^-1 and 1.75-5.25 μg.L^-1, respectively. Cu contents in most of the monitoring sites in April were meeting Grade III or Grade IV in National Sea Water Quality Standard (GB 3097-1997). While most of the monitoring sites in June, July and October were meeting Grade I or Grade II. The major Zn sources in the bay was overland runoff, ocean current, and deposition, whose input contents ranged from 37.90-167.71 μg.L^-1, 1.31-36.97μg.L^-1 and 1.75-12.18 μg.L^-1.

Abstract: This paper suggests methods of using of alternative sources of energy for SIP-houses building in conditions of Kazakhstan. The model of "Polygon for the use of renewable energy” was developed. This model demonstrates possibilities of transforming wind and solar energy into electric and heating energy.

Abstract: Global warming is one of the key fields of global change ecology．The sources and sinks of the Greenhouse Gases (GHGes) in the atmosphere：which result in climate warming have been widely investigated around the world in the last 1 0 years．In this paper, sources and sinks of main GHGes in the atmosphere(CO2，CH4，N20)were reviewed．It is believed that the emission／uptake flux of the 3 GHGes between the atmosphere and various ecosystems were not precisely quauntified yet and there are some uncertainties with aspect to the：kind of source and sink．By analyzing related literature, the trends of international：research on the source and sink of the main GHGes were summarized as follows：more and more advanced instruments have been used in the research，more an d more regions have been investigated，more and more concerns have been on the response of emission／uptake flux of the 3 GHGes to the global change an d integrated research comprising ecology ,soil biology, meteorology, microbiology, atmospheric physics，etc．In our country, the research on source and sink of the 3 GHGes were developed since 1 980s．Compared with advanced countries，our related researches were conducted in fewer sites with less frequency and were less systematic． the rapid development so far involved CH4 emission from rice paddies, wetlands, CH4 and N2O emissions from the study of loess - paleosol sequence composition characteristics of greenhouse gases, and forest, agriculture, Soil CO2 emission and absorption of research in the field.

Abstract: Based on investigation dada on Cr in 1982 in Jiaozhou Bay, this paper analyzed the seasonal and spatial distribution of Cr, and revealed the transfer process of Cr. Results showed that horizontal diffusion and vertical sedimentation were major transfer processes of Cr, which were mainly determined by water exchange and gravity settling. These findings were essential to pollution control and environmental remediation in Jiaozhou Bay. From the point of view of pollution control, reducing the discharge of Cr from the sources was the major countermeasure.

Abstract: Heavy metals (including As, Cd, Pb, Ti, V, Cr, Mn, Ni, Cu and Zn) concentration analysis for soil samples from Westhill (near Huoshaogou) and source assessment of heavy metals in sludge from Huoshaogou wetland park in Xining city (China) have been carried out. Results show that Cd, Pb, Cr and Zn concentrations in the surface soil are much higher than that in the unpolluted soil from Westhill, and Cr concentration in the sludge from Huoshaogou wetland reaches 12 times and 6 times more than that in the unpolluted and in the surface soils from Westhill, respectively. The results reveal that descent of dust contributed Cd, Pb, Cr and Zn to the wetland, and wastewater mainly contributed Cr to the wetland. In order to protect the environment, human activities and heavy metal discharge should be limited effectively.

Abstract: Based on the investigation data of Plumbum (Pb) in surface waters in Jiaozhou Bay in April, August and November 1981, this paper analyzed the content, distribution and source of Pb. Results showed that Pb contents in April, August and November ranged from 0.20-2.65 μg. L^-1, 0.79-3.34 μg. L^-1 and 0.00-3.00 μg. L^-1, respectively, all of which were lower than Grade II (5.00 μg.L^-1) in according to National Standard of China for Seawater Quality (GB3097-1997). Agricultural non-point source and urban point source were the major pollution source of Pb in spring (growing season) and autumn (dry season), respectively; while both point and non-point sources were responsible in summer (wet season).