对我国大洋第19航次第Ⅱ航段在西南印度洋脊49°39′E热液区利用电视抓斗获取的热液硫化物烟囱体(Tao C et al.,2007)样品从内到外取了5个小样,进行了铂族元素含量分析,样品的PGE含量较低且变化范围较大。PGE中平均含量最高的Pt和P...对我国大洋第19航次第Ⅱ航段在西南印度洋脊49°39′E热液区利用电视抓斗获取的热液硫化物烟囱体(Tao C et al.,2007)样品从内到外取了5个小样,进行了铂族元素含量分析,样品的PGE含量较低且变化范围较大。PGE中平均含量最高的Pt和Pd仅分别为0.667ng/g和0.展开更多
Rivers often witness non-uniform bed load sedim ent transport. For a long tim e, non-uniform bed load transport has been assum ed to be at capacity regime determined exclusively by local flow. Yet whether the capacity...Rivers often witness non-uniform bed load sedim ent transport. For a long tim e, non-uniform bed load transport has been assum ed to be at capacity regime determined exclusively by local flow. Yet whether the capacity assumption for non-uniform bed load transport is justified remains poorly understood. Here, the relative time scale of non-uniform bed load transport is evaluated and non-capacity and capacity models are compared for both aggradation and degradation cases with observed data. As characterized by its relative time scale, the adaptation of non-uniform bed load to capacity regime should be fulfilled quickly. However, changes in the flow and sedim ent inputs from upstream or tributaries hinder the adaptation. Also, the adaptation to capacity regime is size dependent, the finer the sediment size the slower the adaptation is, and vice versa. It is shown that the capacity model may entail considerable errors compared to the non-capacity model. For modelling of non-uniform bed load, non-capacity modelling is recommended, in which the temporal and spatial scales required for adaptation are explicitly appreciated.展开更多
The objective of this research was to enhance adsorption capacity of Acacia nilotica （keekar） sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorptio...The objective of this research was to enhance adsorption capacity of Acacia nilotica （keekar） sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorption capacity. The sawdust was activated by acid wash and functionalized subsequently with formaldehyde. Functionalization of activated sawdust raised its chromium removal efficiency of almost 10% as compared to its adsorption removal efficiency of HCl treated sawdust in a batch adsorption study. Adsorption kinetic data provided better fitting with pseudo second order model. Maximum adsorption capacity calculated through the best fitting Langmuir model was 6.34 mg·g^-1 and 8.2 mg·g^-1 for HCl treated and formaldehyde functionalized sawdust adsorbents, respectively. The adsorption of Cr（VI） was endothermic when studied by varying temperature from 20℃ to 50℃ for both activated and functionalized adsorbents.展开更多
On lunar exploration missions, the rovers which can move and explore directly are considered by various agency like NASA （National Aeronautics and Space Administration）, JAXA （Japan Aerospace Exploration Agency）, ...On lunar exploration missions, the rovers which can move and explore directly are considered by various agency like NASA （National Aeronautics and Space Administration）, JAXA （Japan Aerospace Exploration Agency）, ESA （European Space Agency）. Lunar rovers are required to move on rough terrains such as craters and rear cliffs where it is scientifically very important to explore. However, there is a problem that the rovers have possibility of stack because of the lunar surface is covered with loose soil named Regolith. Therefore, this paper investigates a mechanism of kinetic behavior between the wheels of the exploration rovers and loose soil. And then, this paper proposed a flexible wheel to solve like that problems. The flexible wheel has the surface which can be changed flexibly toward rough terrain. Running experiments on loose soil which imitated regolith were carried out to observe the traversability of the flexible wheel using slip ratio. Traversality of flexible wheel was better than the circular rigid wheel. The authors believe that stress distribution is important. The stress distribution of the flexible wheels is horizontally long and stress value is small. However, the stress distribution can be changed by loaded more weight. Therefore, the relationship between the stress and the running performance was considered using this differential stress distribution. In experiments, the authors used the flexible wheel with simple structure （3 limbs）. From these considerations, the relationship between the stress of the flexible wheel and the running performance was described.展开更多
基金funded by the N atural Science Foundation of China (G rants No. 11172217, 51279144 and 11432015)Chinese Academy of Sciences (G rant No. KZZDEW -05-01-03)
文摘Rivers often witness non-uniform bed load sedim ent transport. For a long tim e, non-uniform bed load transport has been assum ed to be at capacity regime determined exclusively by local flow. Yet whether the capacity assumption for non-uniform bed load transport is justified remains poorly understood. Here, the relative time scale of non-uniform bed load transport is evaluated and non-capacity and capacity models are compared for both aggradation and degradation cases with observed data. As characterized by its relative time scale, the adaptation of non-uniform bed load to capacity regime should be fulfilled quickly. However, changes in the flow and sedim ent inputs from upstream or tributaries hinder the adaptation. Also, the adaptation to capacity regime is size dependent, the finer the sediment size the slower the adaptation is, and vice versa. It is shown that the capacity model may entail considerable errors compared to the non-capacity model. For modelling of non-uniform bed load, non-capacity modelling is recommended, in which the temporal and spatial scales required for adaptation are explicitly appreciated.
文摘The objective of this research was to enhance adsorption capacity of Acacia nilotica （keekar） sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorption capacity. The sawdust was activated by acid wash and functionalized subsequently with formaldehyde. Functionalization of activated sawdust raised its chromium removal efficiency of almost 10% as compared to its adsorption removal efficiency of HCl treated sawdust in a batch adsorption study. Adsorption kinetic data provided better fitting with pseudo second order model. Maximum adsorption capacity calculated through the best fitting Langmuir model was 6.34 mg·g^-1 and 8.2 mg·g^-1 for HCl treated and formaldehyde functionalized sawdust adsorbents, respectively. The adsorption of Cr（VI） was endothermic when studied by varying temperature from 20℃ to 50℃ for both activated and functionalized adsorbents.
文摘On lunar exploration missions, the rovers which can move and explore directly are considered by various agency like NASA （National Aeronautics and Space Administration）, JAXA （Japan Aerospace Exploration Agency）, ESA （European Space Agency）. Lunar rovers are required to move on rough terrains such as craters and rear cliffs where it is scientifically very important to explore. However, there is a problem that the rovers have possibility of stack because of the lunar surface is covered with loose soil named Regolith. Therefore, this paper investigates a mechanism of kinetic behavior between the wheels of the exploration rovers and loose soil. And then, this paper proposed a flexible wheel to solve like that problems. The flexible wheel has the surface which can be changed flexibly toward rough terrain. Running experiments on loose soil which imitated regolith were carried out to observe the traversability of the flexible wheel using slip ratio. Traversality of flexible wheel was better than the circular rigid wheel. The authors believe that stress distribution is important. The stress distribution of the flexible wheels is horizontally long and stress value is small. However, the stress distribution can be changed by loaded more weight. Therefore, the relationship between the stress and the running performance was considered using this differential stress distribution. In experiments, the authors used the flexible wheel with simple structure （3 limbs）. From these considerations, the relationship between the stress of the flexible wheel and the running performance was described.
