为了研究He在材料中的行为,借助10B的(n,α)核反应,通过反应堆热中子对Al-B合金进行辐照,引入He原子密度达6.2×1025 m-3。采用同步辐射X射线小角散射法(Synchrotron small angle X-ray scattering,SAXS)原位测试了不同温度下合金...为了研究He在材料中的行为,借助10B的(n,α)核反应,通过反应堆热中子对Al-B合金进行辐照,引入He原子密度达6.2×1025 m-3。采用同步辐射X射线小角散射法(Synchrotron small angle X-ray scattering,SAXS)原位测试了不同温度下合金中He的状态变化,并结合透射电镜(Transmission electron microscope,TEM)对试样进行了观察;采用X射线衍射和中子衍射法分析了合金晶格参数的变化。SAXS分析表明,随着温度升高试样内部的颗粒和孔洞消失,He泡数量不断增多、尺寸增大。700 oC下He泡的半径大约增大到10 nm,与室温时颗粒和孔洞相当。衍射分析表明,B原子引入使得Al晶格常数增大,但不存在可见的第二相,中子辐照使得生成的Li和He原子进入Al晶格,进一步加大了晶格常数。辐照后的样品加热使得He从晶格间隙位置扩散到晶界形成He泡,从而缓解了对晶格的挤压,导致了晶格常数的回复减小,第一性原理计算得到的间隙原子B、Li、He引起的晶格肿胀解释了这一结果。展开更多
The existence of global solution and the blow-up problem for a model of nuclear reactorsare discussed by using the upper-lower solution and energy estimate methods; asymptoticbehavior of global solution is also discus...The existence of global solution and the blow-up problem for a model of nuclear reactorsare discussed by using the upper-lower solution and energy estimate methods; asymptoticbehavior of global solution is also discussed with the aid of L_p estimate and semigroupmethod for this model. Nice results, which explain the phenomenon of nuclear reactorsbetter, are obtained.展开更多
A powerful non-destructive testing (NDT) technique is adopted to study the quality of RHA brick-1 and RHA brick-2. In that case, rice husk ash has been utilized for the preparation of bricks in full replacement of cla...A powerful non-destructive testing (NDT) technique is adopted to study the quality of RHA brick-1 and RHA brick-2. In that case, rice husk ash has been utilized for the preparation of bricks in full replacement of clay. In these studies, homogeneity of elemental distribution, water absorption and size and shape of the pores have been observed. From the studies, it was observed that elemental distribution is very good at various level, large number of porosity is presented with little bit size, initial rate of absorption (IRA) due to first five minutes immersion of water is higher compared to other immersion time (>5 minute), incremental water intrusion area increases very slowly with the increasing immersion time and the water absorption for RHA brick-2 becomes saturated very early than that of the RHA brick-1.展开更多
Neutron radiography (NR) technique has been adopted to study the internal structure and quality of the KAB bricks made by Hoffman kiln method. Thermal neutron radiography facility installed at the tangential beam port...Neutron radiography (NR) technique has been adopted to study the internal structure and quality of the KAB bricks made by Hoffman kiln method. Thermal neutron radiography facility installed at the tangential beam port of 3 MW TRIGA Mark-II Research Reactor, AERE, Savar, Dhaka, Bangladesh is used in the present study. Measurements were made to determine the internal structure and quality of the automated machine made environmentally friendly brick sample. In this case, optical density/gray values of the neutron radiographic images of the sample have been measured. From these measurements, the porosity, water penetrating height, water penetrating behavior, initial rapid absorption of water (IRA), elemental distribution/homogeneity and incremental water intrusion area in the sample have been found. From the observation of different properties, it is seen that, homogeneity of the Hoffman kiln brick KAB is not perfectly homogeneous and contains small internal porosity;the incremental water intrusion area is very poor, and the water penetrating height through the two edges is higher than the middle part;the initial rapid absorption (IRA) rate is also very poor and the water penetrating behavior of the samples is different as like as stair, capillary, wave and zigzag shape. From these points of view, it is concluded that the quality of the environmentally friendly brick KAB is better. The results obtained and conclusion made in this study can only be compared to the properties of bricks produced under similar conditions with similar raw materials.展开更多
文摘为了研究He在材料中的行为,借助10B的(n,α)核反应,通过反应堆热中子对Al-B合金进行辐照,引入He原子密度达6.2×1025 m-3。采用同步辐射X射线小角散射法(Synchrotron small angle X-ray scattering,SAXS)原位测试了不同温度下合金中He的状态变化,并结合透射电镜(Transmission electron microscope,TEM)对试样进行了观察;采用X射线衍射和中子衍射法分析了合金晶格参数的变化。SAXS分析表明,随着温度升高试样内部的颗粒和孔洞消失,He泡数量不断增多、尺寸增大。700 oC下He泡的半径大约增大到10 nm,与室温时颗粒和孔洞相当。衍射分析表明,B原子引入使得Al晶格常数增大,但不存在可见的第二相,中子辐照使得生成的Li和He原子进入Al晶格,进一步加大了晶格常数。辐照后的样品加热使得He从晶格间隙位置扩散到晶界形成He泡,从而缓解了对晶格的挤压,导致了晶格常数的回复减小,第一性原理计算得到的间隙原子B、Li、He引起的晶格肿胀解释了这一结果。
文摘The existence of global solution and the blow-up problem for a model of nuclear reactorsare discussed by using the upper-lower solution and energy estimate methods; asymptoticbehavior of global solution is also discussed with the aid of L_p estimate and semigroupmethod for this model. Nice results, which explain the phenomenon of nuclear reactorsbetter, are obtained.
文摘A powerful non-destructive testing (NDT) technique is adopted to study the quality of RHA brick-1 and RHA brick-2. In that case, rice husk ash has been utilized for the preparation of bricks in full replacement of clay. In these studies, homogeneity of elemental distribution, water absorption and size and shape of the pores have been observed. From the studies, it was observed that elemental distribution is very good at various level, large number of porosity is presented with little bit size, initial rate of absorption (IRA) due to first five minutes immersion of water is higher compared to other immersion time (>5 minute), incremental water intrusion area increases very slowly with the increasing immersion time and the water absorption for RHA brick-2 becomes saturated very early than that of the RHA brick-1.
文摘Neutron radiography (NR) technique has been adopted to study the internal structure and quality of the KAB bricks made by Hoffman kiln method. Thermal neutron radiography facility installed at the tangential beam port of 3 MW TRIGA Mark-II Research Reactor, AERE, Savar, Dhaka, Bangladesh is used in the present study. Measurements were made to determine the internal structure and quality of the automated machine made environmentally friendly brick sample. In this case, optical density/gray values of the neutron radiographic images of the sample have been measured. From these measurements, the porosity, water penetrating height, water penetrating behavior, initial rapid absorption of water (IRA), elemental distribution/homogeneity and incremental water intrusion area in the sample have been found. From the observation of different properties, it is seen that, homogeneity of the Hoffman kiln brick KAB is not perfectly homogeneous and contains small internal porosity;the incremental water intrusion area is very poor, and the water penetrating height through the two edges is higher than the middle part;the initial rapid absorption (IRA) rate is also very poor and the water penetrating behavior of the samples is different as like as stair, capillary, wave and zigzag shape. From these points of view, it is concluded that the quality of the environmentally friendly brick KAB is better. The results obtained and conclusion made in this study can only be compared to the properties of bricks produced under similar conditions with similar raw materials.
