Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER...Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER） is often used to indicate the air flow condition. Based on a fuel cell system model for vehicles, OER performance was analyzed for different stack currents and temperatures in this paper, and the results show that the optimal OER was affected weakly by the stack temperature. In order to ensure the system working in optimal OER, a control scheme that includes an optimal OER regulator and a fuzzy control was proposed. According to the stack current, a reference value of air flow rate was obtained with the optimal OER regulator and then the air compressor motor voltage was controlled with the fuzzy controller to adjust the air flow rate provided by the air compressor. Simulation results show that the control method has good dynamic and static characteristics.展开更多
氨气(NH_(3))作为一种兼具储能的无碳燃料,在能源领域具有极大的应用前景。然而,NH_(3)的燃烧特性与常规碳氢燃料有着明显差异。该文通过数值模拟方法,研究了CH_(4)/NH_(3)的混合燃料低氧稀释(moderate or intense low-oxygen dilution,...氨气(NH_(3))作为一种兼具储能的无碳燃料,在能源领域具有极大的应用前景。然而,NH_(3)的燃烧特性与常规碳氢燃料有着明显差异。该文通过数值模拟方法,研究了CH_(4)/NH_(3)的混合燃料低氧稀释(moderate or intense low-oxygen dilution,MILD)燃烧特性。结果表明,在甲烷MILD燃烧中添加NH_(3)使出口NO排放亟剧增加。过量空气系数大于1时,减小过量空气系数使NO和CO的排放降低。NH_(3)中的N元素转化成NO的转化率随燃料中NH_(3)的增加和过量空气系数的降低而减小。展开更多
The influence of oxygen defects upon the electronic properties of Nb-doped TiO2 has been studied by using the general gradient approximation （GGA）＋U method. Four independent models （i.e., an undoped anatase cell, ...The influence of oxygen defects upon the electronic properties of Nb-doped TiO2 has been studied by using the general gradient approximation （GGA）＋U method. Four independent models （i.e., an undoped anatase cell, an anatase cell with a Nb dopant at Ti site （NbTi）, an anatase cell with a Nb-dopant and an oxygen vacancy （NbTi＋Vo）, and an anatase cell with a Nb-dopant and an interstitial oxygen （NbTi＋Oi）） were considered. The density of states, effective mass, Bader charge, charge density, and electron localization function were calcul^ited. The results show that in the NbTi＋Vo cell both eg and t2g levels of Ti 3d orbits make contributions to the electronic conductivity, and the oxygen vacancies （Vo） collaborate with Nb-dopants to favor the high electrical conductivity by inducing the Nb-dopants to release more excess charges. In NbTi＋Oi, an unoccupied impurity level appears in the band gap, which served as an acceptor level and suppressed the electronic conductivity. The results qualitatively coincide with experimental results and possibly provide insights into the preparation of TCOs with desirable conductivity.展开更多
目的探讨铁蓄积通过氧化应激-自噬对雌性SD大鼠骨代谢的影响及相关机制。方法60只健康雌性SD大鼠随机分为假手术组(SHAM组)、去卵巢组(OVX组)、去卵巢+枸橼酸铁铵组(OVX+FAC组)、去卵巢+枸橼酸铁铵+谷胱甘肽组(OVX+FAC+GSH组)、去卵巢+...目的探讨铁蓄积通过氧化应激-自噬对雌性SD大鼠骨代谢的影响及相关机制。方法60只健康雌性SD大鼠随机分为假手术组(SHAM组)、去卵巢组(OVX组)、去卵巢+枸橼酸铁铵组(OVX+FAC组)、去卵巢+枸橼酸铁铵+谷胱甘肽组(OVX+FAC+GSH组)、去卵巢+枸橼酸铁铵+去铁胺组(OVX+FAC+DFO组)。采用ELISA法检测大鼠血清血清活性氧(reactive oxygen species,ROS)、Ⅰ型胶原的N-末端前肽(N-terminal propeptide of typeⅠcollagen,P1NP)、骨特异性碱性磷酸酶(bone-specific alkphase,B-ALP)、Ⅰ型胶原C末端肽(C-terminal telopeptide of typeⅠcollagen,CTX)、抗酒石酸酸性磷酸酶(tartrate resistant acid phosphatase 5b,TRACP-5b),micro-CT扫描大鼠股骨并分析骨微结构,透射电镜观察胫骨自噬体,Western blot检测骨组织内微管相关蛋白1轻链3(microtubule-associated protein 1 light chain 3,LC3)、叉头框蛋白O3(forkhead box protein O3,FOXO3)、自噬相关蛋白7(autophagy related gene 7,ATG7)的蛋白表达水平。结果各组血清ROS水平较SHAM组显著升高(P<0.01),OVX+FAC组血清ROS水平较OVX组显著升高(P<0.01),GSH和DFO可以显著降低去卵巢铁蓄积大鼠血清ROS水平(P<0.05)。各组血清中P1NP、B-ALP、CTX、TRACP-5b含量较SHAM组均升高(P<0.05),以OVX+FAC组显著(P<0.01);与OVX组、OVX+FAC组比较,GSH和DFO均显著降低血清中P1NP、B-ALP、CTX、TRACP-5b含量(P<0.01)。与SHAM组比较,各组大鼠骨小梁骨密度(trabecular bone mineral density,Tb.BMD)、骨体积分数(bone volume fration,BV/TV)、骨小梁数量(trabecular number,Tb.N)、骨小梁厚度(trabecular thichness,Tb.Th)均明显下降(P<0.05),骨小梁分离度(trabecular separation,Tb.Sp)、骨小梁模式因子(trabecular pattern factor,Tb.Pf)、结构模型指数(stucture model index,SMI)明显增加(P<0.05),以OVX+FAC组变化最为明显(P<0.05);与OVX组和OVX+FAC组比较,GSH和DFO可增加大鼠股骨BMD、BV/TV、Tb.N和Tb.Th(P<0.05),减少Tb.Sp、Tb.Pf和SMI(P<0.05);与GSH比较,DFO在改善BMD、BV/TV、Tb.N和Tb.Pf方面显著(P<0.05)。各组大鼠骨组织中LC3-Ⅱ/LC3-Ⅰ比值、FOXO3和ATG7蛋白表达较SHAM组增加(P<0.05),自噬体数量增加,以OVX+FAC组增加最为显著(P<0.01);与OVX组、OVX+FAC组比较,GSH和DFO均可降低骨组织中LC3-Ⅱ/LC3-Ⅰ比值和下调FOXO3和ATG7蛋白表达(P<0.05),自噬体数量减少。结论铁蓄积可通过产生的ROS激活FOXO3以促进自噬,导致骨量减少和骨质疏松;抗氧化和降铁后可改善骨量。展开更多
In order to study the effect of excess sludge ozonation, a continuous experiment in lab scale process was carried out. During the treatment process, a high level of ozone was produced by the electrolysis-type ozone ge...In order to study the effect of excess sludge ozonation, a continuous experiment in lab scale process was carried out. During the treatment process, a high level of ozone was produced by the electrolysis-type ozone generator, and various parameters, such as Soluble Chemical Oxygen Demand （SCOD）, Mixed Liquor Suspended Solids （MLSS）, Mixed Liquor Volatile Suspended Solids （MLVSS）, pH and so on, which char- acterize sludge were investigated. A substantial reduction in the volume of sludge and the release of intracellular materials were observed： SCOD proliferated as a consequence of extending the ozone feeding time; MLSS and MLVSS, especially the ratio of MLVSS to MLSS, dwindled as the action time rose. Through analyzing the effluent quality and excess sludge activity, the sludge-water volume mixture ratio of 1 ： 20 with 50 -60 minutes＇ oxidation treatment was found to be the optimal condition for ozonic disintegration of excess sludge. A remarkable sludge reduction rate of 57% could be achieved under the ozone feeding time of 40 minutes, which revealed the optimal action time.展开更多
基金supported by the National Natural Science Foundation of China (No. 51177138)the Research Fund for the Doctoral Program of High Education of China (No.20100184110015)Sichuan Province International Technology Cooperation and Exchange Program (No. 2012HH0007)
文摘Air flow control is one of the most important control methods for maintaining the stability and reliability of a fuel cell system, which can avoid oxygen starvation or oxygen saturation. The oxygen excess ratio （OER） is often used to indicate the air flow condition. Based on a fuel cell system model for vehicles, OER performance was analyzed for different stack currents and temperatures in this paper, and the results show that the optimal OER was affected weakly by the stack temperature. In order to ensure the system working in optimal OER, a control scheme that includes an optimal OER regulator and a fuzzy control was proposed. According to the stack current, a reference value of air flow rate was obtained with the optimal OER regulator and then the air compressor motor voltage was controlled with the fuzzy controller to adjust the air flow rate provided by the air compressor. Simulation results show that the control method has good dynamic and static characteristics.
文摘氨气(NH_(3))作为一种兼具储能的无碳燃料,在能源领域具有极大的应用前景。然而,NH_(3)的燃烧特性与常规碳氢燃料有着明显差异。该文通过数值模拟方法,研究了CH_(4)/NH_(3)的混合燃料低氧稀释(moderate or intense low-oxygen dilution,MILD)燃烧特性。结果表明,在甲烷MILD燃烧中添加NH_(3)使出口NO排放亟剧增加。过量空气系数大于1时,减小过量空气系数使NO和CO的排放降低。NH_(3)中的N元素转化成NO的转化率随燃料中NH_(3)的增加和过量空气系数的降低而减小。
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51002135 and 51172200)the Fundamental Research Funds for the Central Universities of Ministry of Education of China(Grant No.2013QNA4011)
文摘The influence of oxygen defects upon the electronic properties of Nb-doped TiO2 has been studied by using the general gradient approximation （GGA）＋U method. Four independent models （i.e., an undoped anatase cell, an anatase cell with a Nb dopant at Ti site （NbTi）, an anatase cell with a Nb-dopant and an oxygen vacancy （NbTi＋Vo）, and an anatase cell with a Nb-dopant and an interstitial oxygen （NbTi＋Oi）） were considered. The density of states, effective mass, Bader charge, charge density, and electron localization function were calcul^ited. The results show that in the NbTi＋Vo cell both eg and t2g levels of Ti 3d orbits make contributions to the electronic conductivity, and the oxygen vacancies （Vo） collaborate with Nb-dopants to favor the high electrical conductivity by inducing the Nb-dopants to release more excess charges. In NbTi＋Oi, an unoccupied impurity level appears in the band gap, which served as an acceptor level and suppressed the electronic conductivity. The results qualitatively coincide with experimental results and possibly provide insights into the preparation of TCOs with desirable conductivity.
文摘目的探讨铁蓄积通过氧化应激-自噬对雌性SD大鼠骨代谢的影响及相关机制。方法60只健康雌性SD大鼠随机分为假手术组(SHAM组)、去卵巢组(OVX组)、去卵巢+枸橼酸铁铵组(OVX+FAC组)、去卵巢+枸橼酸铁铵+谷胱甘肽组(OVX+FAC+GSH组)、去卵巢+枸橼酸铁铵+去铁胺组(OVX+FAC+DFO组)。采用ELISA法检测大鼠血清血清活性氧(reactive oxygen species,ROS)、Ⅰ型胶原的N-末端前肽(N-terminal propeptide of typeⅠcollagen,P1NP)、骨特异性碱性磷酸酶(bone-specific alkphase,B-ALP)、Ⅰ型胶原C末端肽(C-terminal telopeptide of typeⅠcollagen,CTX)、抗酒石酸酸性磷酸酶(tartrate resistant acid phosphatase 5b,TRACP-5b),micro-CT扫描大鼠股骨并分析骨微结构,透射电镜观察胫骨自噬体,Western blot检测骨组织内微管相关蛋白1轻链3(microtubule-associated protein 1 light chain 3,LC3)、叉头框蛋白O3(forkhead box protein O3,FOXO3)、自噬相关蛋白7(autophagy related gene 7,ATG7)的蛋白表达水平。结果各组血清ROS水平较SHAM组显著升高(P<0.01),OVX+FAC组血清ROS水平较OVX组显著升高(P<0.01),GSH和DFO可以显著降低去卵巢铁蓄积大鼠血清ROS水平(P<0.05)。各组血清中P1NP、B-ALP、CTX、TRACP-5b含量较SHAM组均升高(P<0.05),以OVX+FAC组显著(P<0.01);与OVX组、OVX+FAC组比较,GSH和DFO均显著降低血清中P1NP、B-ALP、CTX、TRACP-5b含量(P<0.01)。与SHAM组比较,各组大鼠骨小梁骨密度(trabecular bone mineral density,Tb.BMD)、骨体积分数(bone volume fration,BV/TV)、骨小梁数量(trabecular number,Tb.N)、骨小梁厚度(trabecular thichness,Tb.Th)均明显下降(P<0.05),骨小梁分离度(trabecular separation,Tb.Sp)、骨小梁模式因子(trabecular pattern factor,Tb.Pf)、结构模型指数(stucture model index,SMI)明显增加(P<0.05),以OVX+FAC组变化最为明显(P<0.05);与OVX组和OVX+FAC组比较,GSH和DFO可增加大鼠股骨BMD、BV/TV、Tb.N和Tb.Th(P<0.05),减少Tb.Sp、Tb.Pf和SMI(P<0.05);与GSH比较,DFO在改善BMD、BV/TV、Tb.N和Tb.Pf方面显著(P<0.05)。各组大鼠骨组织中LC3-Ⅱ/LC3-Ⅰ比值、FOXO3和ATG7蛋白表达较SHAM组增加(P<0.05),自噬体数量增加,以OVX+FAC组增加最为显著(P<0.01);与OVX组、OVX+FAC组比较,GSH和DFO均可降低骨组织中LC3-Ⅱ/LC3-Ⅰ比值和下调FOXO3和ATG7蛋白表达(P<0.05),自噬体数量减少。结论铁蓄积可通过产生的ROS激活FOXO3以促进自噬,导致骨量减少和骨质疏松;抗氧化和降铁后可改善骨量。
基金Supported by the Fundamental Research Funds for the Central Universities(2010380003161543)Science and Technology Project of Science and Technology Department of Guangdong Province,China(2010B031700023)
文摘In order to study the effect of excess sludge ozonation, a continuous experiment in lab scale process was carried out. During the treatment process, a high level of ozone was produced by the electrolysis-type ozone generator, and various parameters, such as Soluble Chemical Oxygen Demand （SCOD）, Mixed Liquor Suspended Solids （MLSS）, Mixed Liquor Volatile Suspended Solids （MLVSS）, pH and so on, which char- acterize sludge were investigated. A substantial reduction in the volume of sludge and the release of intracellular materials were observed： SCOD proliferated as a consequence of extending the ozone feeding time; MLSS and MLVSS, especially the ratio of MLVSS to MLSS, dwindled as the action time rose. Through analyzing the effluent quality and excess sludge activity, the sludge-water volume mixture ratio of 1 ： 20 with 50 -60 minutes＇ oxidation treatment was found to be the optimal condition for ozonic disintegration of excess sludge. A remarkable sludge reduction rate of 57% could be achieved under the ozone feeding time of 40 minutes, which revealed the optimal action time.
