The unit cell volume and phase transition temperature of LaFe11.4Al1.6Cx compounds have been studied. The magnetic entropy change, refrigerant capacity and the type of magnetic phase transition are investigated in det...The unit cell volume and phase transition temperature of LaFe11.4Al1.6Cx compounds have been studied. The magnetic entropy change, refrigerant capacity and the type of magnetic phase transition are investigated in detail for LaFe11.4Al1.6Cx with x=0.1, All the LaFe11.4Al1.6Cx (x=0-0.8) compounds have the cubic NaZn13-type structure. The addition of carbon atoms brings about a considerable increase in the lattice parameter. The bulk expansion results in the change of phase transition temperature (Tc), Tc increases from 187K to 269 K with x varying from 0.1 to 0.8, Meanwhile an increase in the lattice parameter can also cause a change of the magnetic ground state from antiferromagnetic to ferromagnetic. Large magnetic entropy change IASI is found over a large temperature range around Tc and the refrigerant capacity is about 322J/kg for LaFe11.4Al1.6C0.1. The magnetic phase transition belongs in weakly first-order one for x=0.1.展开更多
Land use/land cover (LULC) changes have become a central issue in current global change and sustainability research. Saudi Arabia has undergone significant change in land use and land cover since the government embark...Land use/land cover (LULC) changes have become a central issue in current global change and sustainability research. Saudi Arabia has undergone significant change in land use and land cover since the government embarked on a course of intense national development 30 years ago, as a result of huge national oil revenues. This study evaluates LULC change in Makkah and Al-Taif, Saudi Arabia from 1986 to 2013 using Landsat images. Maximum likelihood and object-oriented classification were used to develop LULC maps. The change detection was executed using post-classification comparison and GIS. The results indicated that urban areas have increased over the period by approximately 174% in Makkah and 113% in Al-Taif. Analysis of vegetation cover over the study area showed a variable distribution from year to year due to changing average precipitation in this environment. Object-based classification provided slightly greater accuracy than maximum likelihood classification. Information provided by satellite remote sensing can play an important role in quantifying and understanding the relationship between population growth and LULC changes, which can assist future planning and potential environmental impacts of expanding urban areas.展开更多
The selecting of a site for landfill is considered as a difficult process because many criteria should be involved. The main aim of establishing a landfill is to protect the human and environment. Al-Qasim district is...The selecting of a site for landfill is considered as a difficult process because many criteria should be involved. The main aim of establishing a landfill is to protect the human and environment. Al-Qasim district is considered as the study area in this work. It is one of the main districts in Babylon Governorate, Iraq. There is no systematic site as landfill that fulfil the environmental and scientific criteria in this area. Therefore, the most important fifteen criteria that suited the environmental requirements were selected in the current study.?These criteria are: groundwater depth, urban centers, rivers, villages, soil types, elevation, roads agricultural land use, slope, land use, archaeological sites, power lines, gas pipelines, oil pipelines and railways. Two methods of multi criteria decision making AHP (analytical hierarchy process) and SRS (straight rank sum) were applied to obtain the weights of criteria in dissimilar styles. The raster maps of the selected criteria were prepared and analyzed within the GIS software. Then, the change detection method was implemented to compare the two output raster maps resulted from AHP and SRS methods. Two appropriate candidate sites for landfill were selected to accommodate the cumulative solid waste until the year 2030 in Qasim district. The areas of these sites were 2.766 km2 and 2.055 km2 respectively.展开更多
We expose the results of the study of the south-western Alboran seismic sequence of January-March 2016 and the stress perturbations it caused by means of Coulomb modeling. The use of data from numerous stations allowe...We expose the results of the study of the south-western Alboran seismic sequence of January-March 2016 and the stress perturbations it caused by means of Coulomb modeling. The use of data from numerous stations allowed us to relocate the largest events (Mw ≥ 3.8) south of those determined by IGN (Spain). The main shock of 25 January 2016 (Mw = 6.3) was relocated at 35.6133°N × 3.6888°W, at a hypocentral depth of 15.5 ± 6.0 km. The epicenters are aligned along two distinct clusters: The first runs N-S towards the Moroccan coast along Al-Idrissi fracture zone, while the second is centered on the Alboran ridge northern thrust fault. The focal mechanisms determined by different agencies correspond to a strike-slip/normal/reverse motion in the western cluster and thrusting in the eastern one. Coulomb stress change modeling shows that the main earthquake: (1) may have been triggered by stress accumulation by the 1994 and 2004 earthquakes;(2) has induced stress perturbations that provide a suitable explanation for the distribution of the aftershock clusters, including the eastern cluster. The prediction of the next event shows that it is likely to occur near the Moroccan coast.展开更多
The structural change and mineralogy of Al gel during aging time were investigated by using spectroscopy techniques.The results indicated that:1) the aggregation extent of solution-gel system increases with aging time...The structural change and mineralogy of Al gel during aging time were investigated by using spectroscopy techniques.The results indicated that:1) the aggregation extent of solution-gel system increases with aging time,and the structure of amorphous gel becomes more short-ordered;2) after six months,the gel formats nordstrandite and little gibbsite;3) a marked decrease in the number of(Al-OH)oh bands occurring at 610 cm-1 and increase in the number of(Al-OH2)oh bands occurring at 555 cm-1 indicate that the gel undergoes rearrangement-like process during aging;4) the gel constantly contains Al-O tetrahedron of Keggin structure,but the signal peak occurring at ≈61×10-6 of 27Al MAS NMR have a slight shift to downfield with aging time.A mineralogical transformation mechanism for hydrolysis Al(Ⅲ) solution was proposed.展开更多
Rapidly solidified Al 2.5Ti 2.5Fe 2.5V alloy was prepared by melt spinning. As spun and as annealed microstructures were studied by TEM, HREM, XRD and EDS analysis. The microhardness of the alloy at different annealin...Rapidly solidified Al 2.5Ti 2.5Fe 2.5V alloy was prepared by melt spinning. As spun and as annealed microstructures were studied by TEM, HREM, XRD and EDS analysis. The microhardness of the alloy at different annealing temperature was measured. The results show that the as spun microstructure of the alloy includes four kinds of primary phases: Al 11 (V,Ti), AlTi 3, Al 80 (V,Ti) 20 and Al 82 (Fe,Ti,V) 18 phase. After annealing at 300 ℃ for 10 h, metastable phase Al 82 (Fe,Ti,V) 18 transforms to the stable phase Al 13 Fe 4. After annealing at 400 ℃ for 10 h, the primary phases Al 11 (V,Ti) and AlTi 3 has completely transformed to Al 80 (V,Ti) 20 and Al 23 Ti 9 phase, respectively. The addition of element V increases the microhardness of melt spun Al 2.5Ti 2.5Fe alloy at elevated temperatures.展开更多
对 Si 含量为10%~13%的 Al-Si 合金进行了加速氧化、热循环和掺 Fe 实验,研究了其在不同热循环条件下的相变储热性能和可靠性.结果表明,在空气中经几百 h 的高温氧化后,氧化率小于0.01%,其影响可以忽略不计.经过0,4,23,60, 100,200,...对 Si 含量为10%~13%的 Al-Si 合金进行了加速氧化、热循环和掺 Fe 实验,研究了其在不同热循环条件下的相变储热性能和可靠性.结果表明,在空气中经几百 h 的高温氧化后,氧化率小于0.01%,其影响可以忽略不计.经过0,4,23,60, 100,200,300,400,500,600,700次熔化-凝固循环后,相变温度的变化为3.8~11.8℃,相变潜热从484.86 kJ/kg下降到432.62 kJ/kg.当 Al-Si 合金的掺铁量为0.5%时,相变潜热下降6.5%;对于缓冷的储能过程,偏析较小并在循环多次后趋于缓和和稳定.Al-Si 合金成份和结构的变化对材料的储热性能影响较小,在长期的热循环过程中有良好和稳定的储热性能.展开更多
介绍了La Fe M(M=Al,Si)化合物在磁热性能研究方面的最新进展。具有NaZn13型晶体结构,含高浓度Fe的La Fe M(M=Al,Si)化合物为良好的软磁材料;用少量的Co替代化合物中Si,Al元素可以将化合物的居里温度提高至室温;对La(Fe1-yCoy)xSi13-x...介绍了La Fe M(M=Al,Si)化合物在磁热性能研究方面的最新进展。具有NaZn13型晶体结构,含高浓度Fe的La Fe M(M=Al,Si)化合物为良好的软磁材料;用少量的Co替代化合物中Si,Al元素可以将化合物的居里温度提高至室温;对La(Fe1-yCoy)xSi13-x化合物,适量的Si,Co组合可使化合物在室温产生可与Gd5Si2Ge2比拟的磁热效应;加入适量的间隙原子H,也可使La(FexSi1-x)13在室温的磁热性能远远大于金属Gd;对含Si量低及含Si量高的La(FexSi1-x)13化合物在相转变点附近由温度和磁场诱导相变的本质做了详细阐述。展开更多
基金Project supported by the State Key Program of Basic Research of China (Grant No 2006CB601101), and the National Natural Science Foundation of China ( Grant No 50271082).
文摘The unit cell volume and phase transition temperature of LaFe11.4Al1.6Cx compounds have been studied. The magnetic entropy change, refrigerant capacity and the type of magnetic phase transition are investigated in detail for LaFe11.4Al1.6Cx with x=0.1, All the LaFe11.4Al1.6Cx (x=0-0.8) compounds have the cubic NaZn13-type structure. The addition of carbon atoms brings about a considerable increase in the lattice parameter. The bulk expansion results in the change of phase transition temperature (Tc), Tc increases from 187K to 269 K with x varying from 0.1 to 0.8, Meanwhile an increase in the lattice parameter can also cause a change of the magnetic ground state from antiferromagnetic to ferromagnetic. Large magnetic entropy change IASI is found over a large temperature range around Tc and the refrigerant capacity is about 322J/kg for LaFe11.4Al1.6C0.1. The magnetic phase transition belongs in weakly first-order one for x=0.1.
文摘Land use/land cover (LULC) changes have become a central issue in current global change and sustainability research. Saudi Arabia has undergone significant change in land use and land cover since the government embarked on a course of intense national development 30 years ago, as a result of huge national oil revenues. This study evaluates LULC change in Makkah and Al-Taif, Saudi Arabia from 1986 to 2013 using Landsat images. Maximum likelihood and object-oriented classification were used to develop LULC maps. The change detection was executed using post-classification comparison and GIS. The results indicated that urban areas have increased over the period by approximately 174% in Makkah and 113% in Al-Taif. Analysis of vegetation cover over the study area showed a variable distribution from year to year due to changing average precipitation in this environment. Object-based classification provided slightly greater accuracy than maximum likelihood classification. Information provided by satellite remote sensing can play an important role in quantifying and understanding the relationship between population growth and LULC changes, which can assist future planning and potential environmental impacts of expanding urban areas.
文摘The selecting of a site for landfill is considered as a difficult process because many criteria should be involved. The main aim of establishing a landfill is to protect the human and environment. Al-Qasim district is considered as the study area in this work. It is one of the main districts in Babylon Governorate, Iraq. There is no systematic site as landfill that fulfil the environmental and scientific criteria in this area. Therefore, the most important fifteen criteria that suited the environmental requirements were selected in the current study.?These criteria are: groundwater depth, urban centers, rivers, villages, soil types, elevation, roads agricultural land use, slope, land use, archaeological sites, power lines, gas pipelines, oil pipelines and railways. Two methods of multi criteria decision making AHP (analytical hierarchy process) and SRS (straight rank sum) were applied to obtain the weights of criteria in dissimilar styles. The raster maps of the selected criteria were prepared and analyzed within the GIS software. Then, the change detection method was implemented to compare the two output raster maps resulted from AHP and SRS methods. Two appropriate candidate sites for landfill were selected to accommodate the cumulative solid waste until the year 2030 in Qasim district. The areas of these sites were 2.766 km2 and 2.055 km2 respectively.
文摘We expose the results of the study of the south-western Alboran seismic sequence of January-March 2016 and the stress perturbations it caused by means of Coulomb modeling. The use of data from numerous stations allowed us to relocate the largest events (Mw ≥ 3.8) south of those determined by IGN (Spain). The main shock of 25 January 2016 (Mw = 6.3) was relocated at 35.6133°N × 3.6888°W, at a hypocentral depth of 15.5 ± 6.0 km. The epicenters are aligned along two distinct clusters: The first runs N-S towards the Moroccan coast along Al-Idrissi fracture zone, while the second is centered on the Alboran ridge northern thrust fault. The focal mechanisms determined by different agencies correspond to a strike-slip/normal/reverse motion in the western cluster and thrusting in the eastern one. Coulomb stress change modeling shows that the main earthquake: (1) may have been triggered by stress accumulation by the 1994 and 2004 earthquakes;(2) has induced stress perturbations that provide a suitable explanation for the distribution of the aftershock clusters, including the eastern cluster. The prediction of the next event shows that it is likely to occur near the Moroccan coast.
基金supported by National Natural Science Fund of China (Grant No. 40972110)the specialized research fund for the doctoral program of Higher Education of China (Grant No. 2006029009)the program for New Century Excellent Talents in Universities and Colleges (Grant No. NCET-07-0801)
文摘The structural change and mineralogy of Al gel during aging time were investigated by using spectroscopy techniques.The results indicated that:1) the aggregation extent of solution-gel system increases with aging time,and the structure of amorphous gel becomes more short-ordered;2) after six months,the gel formats nordstrandite and little gibbsite;3) a marked decrease in the number of(Al-OH)oh bands occurring at 610 cm-1 and increase in the number of(Al-OH2)oh bands occurring at 555 cm-1 indicate that the gel undergoes rearrangement-like process during aging;4) the gel constantly contains Al-O tetrahedron of Keggin structure,but the signal peak occurring at ≈61×10-6 of 27Al MAS NMR have a slight shift to downfield with aging time.A mineralogical transformation mechanism for hydrolysis Al(Ⅲ) solution was proposed.
基金Project ( 2 0 0 0JL172 )supportedbytheEducationBureauofAnhuiProvince China
文摘Rapidly solidified Al 2.5Ti 2.5Fe 2.5V alloy was prepared by melt spinning. As spun and as annealed microstructures were studied by TEM, HREM, XRD and EDS analysis. The microhardness of the alloy at different annealing temperature was measured. The results show that the as spun microstructure of the alloy includes four kinds of primary phases: Al 11 (V,Ti), AlTi 3, Al 80 (V,Ti) 20 and Al 82 (Fe,Ti,V) 18 phase. After annealing at 300 ℃ for 10 h, metastable phase Al 82 (Fe,Ti,V) 18 transforms to the stable phase Al 13 Fe 4. After annealing at 400 ℃ for 10 h, the primary phases Al 11 (V,Ti) and AlTi 3 has completely transformed to Al 80 (V,Ti) 20 and Al 23 Ti 9 phase, respectively. The addition of element V increases the microhardness of melt spun Al 2.5Ti 2.5Fe alloy at elevated temperatures.
文摘对 Si 含量为10%~13%的 Al-Si 合金进行了加速氧化、热循环和掺 Fe 实验,研究了其在不同热循环条件下的相变储热性能和可靠性.结果表明,在空气中经几百 h 的高温氧化后,氧化率小于0.01%,其影响可以忽略不计.经过0,4,23,60, 100,200,300,400,500,600,700次熔化-凝固循环后,相变温度的变化为3.8~11.8℃,相变潜热从484.86 kJ/kg下降到432.62 kJ/kg.当 Al-Si 合金的掺铁量为0.5%时,相变潜热下降6.5%;对于缓冷的储能过程,偏析较小并在循环多次后趋于缓和和稳定.Al-Si 合金成份和结构的变化对材料的储热性能影响较小,在长期的热循环过程中有良好和稳定的储热性能.
文摘介绍了La Fe M(M=Al,Si)化合物在磁热性能研究方面的最新进展。具有NaZn13型晶体结构,含高浓度Fe的La Fe M(M=Al,Si)化合物为良好的软磁材料;用少量的Co替代化合物中Si,Al元素可以将化合物的居里温度提高至室温;对La(Fe1-yCoy)xSi13-x化合物,适量的Si,Co组合可使化合物在室温产生可与Gd5Si2Ge2比拟的磁热效应;加入适量的间隙原子H,也可使La(FexSi1-x)13在室温的磁热性能远远大于金属Gd;对含Si量低及含Si量高的La(FexSi1-x)13化合物在相转变点附近由温度和磁场诱导相变的本质做了详细阐述。