The accepted doping ion in Ti^(4+)-site of PbZr_(y)Ti_(1–y)O_(3)(PZT)-based piezoelectric ceramics is a well-known method to increase mechanical quality factor(Q_(m)),since the acceptor coupled by oxygen vacancy beco...The accepted doping ion in Ti^(4+)-site of PbZr_(y)Ti_(1–y)O_(3)(PZT)-based piezoelectric ceramics is a well-known method to increase mechanical quality factor(Q_(m)),since the acceptor coupled by oxygen vacancy becomes defect dipole,which prevents the domain rotation.In this field,a serious problem is that generally,Qm decreases as the temperature(T)increases,since the oxygen vacancies are decoupled from the defect dipoles.In this work,Q_(m) of Pb_(0.95)Sr_(0.05)(Zr_(0.53)Ti_(0.47))O_(3)(PSZT)ceramics doped by 0.40%Fe_(2)O_(3)(in mole)abnormally increases as T increases,of which the Qm and piezoelectric coefficient(d_(33))at room temperature and Curie temperature(TC)are 507,292 pC/N,and 345℃,respectively.The maximum Qm of 824 was achieved in the range of 120–160℃,which is 62.52%higher than that at room temperature,while the dynamic piezoelectric constant(d_(31))was just slightly decreased by 3.85%.X-ray diffraction(XRD)and piezoresponse force microscopy results show that the interplanar spacing and the fine domains form as temperature increases,and the thermally stimulated depolarization current shows that the defect dipoles are stable even the temperature up to 240℃.It can be deduced that the aggregation of oxygen vacancies near the fine domains and defect dipole can be stable up to 240℃,which pins domain rotation,resulting in the enhanced Q_(m) with the increasing temperature.These results give a potential path to design high Q_(m) at high temperature.展开更多
The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributio...The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributions of the critical chloride concentration Cc, the chloride diffusion coefficient D, and the surface chloride concentration Cs were determined based on the collected natural exposure data. And the estimation of probability of corrosion initiation considering the coupling effects of influence factors is presented. It is found that the relative humidity and curing time are the most effective factors affecting the probability of corrosion initiation before and after 10 years of exposure time. At the same exposure time, the influence of load-induced crack and stress state on the probability of corrosion initiation is obvious, in which the effect of crack is the most one展开更多
In a wind-vehicle-bridge(WVB) system,there are various interactions among wind,vehicle and bridge.The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundament...In a wind-vehicle-bridge(WVB) system,there are various interactions among wind,vehicle and bridge.The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundamental factors,such as mean wind,fluctuating wind,buffeting,rail irregularities,light rail vehicle vibration and bridge stiffness.A long cable-stayed bridge which carries light rail traffic is regarded as a numerical example.Firstly,a finite element model is built for the long cable-stayed bridge.The deck can generally be idealized as three-dimensional spine beam while cables are modeled as truss elements.Vehicles are modeled as mass-spring-damper systems.Rail irregularities and wind fluctuation are simulated in time domain by spectrum representation method.Then,aerodynamic loads on vehicle and bridge deck are measured by section model wind tunnel tests.Eight vertical and torsional flutter derivatives of bridge deck are identified by weighting ensemble least-square method.Finally,dynamic responses of the WVB system are analyzed in a series of cases.The results show that the accelerations of the vehicle are excited by the fluctuating wind and the track irregularity to a great extent.The transverse forces of wheel axles mainly depend on the track irregularity.The displacements of the bridge are predominantly determined by the mean wind and restricted by its stiffness.And the accelerations of the bridge are enlarged after adding the fluctuating wind.展开更多
为明晰水肥耦合对炭基质栽培番茄产量品质的提升效应,将生物炭混掺到由酒糟、秸秆等农业废弃物拌制成的基质模块中,设置2个灌溉量(I_(1):100%ET_(c),I_(2):80%ET_(c),ET_(c)为作物蒸发蒸腾量),2个施肥量(N-P_(2)O_(5)-K_(2)O)(F_(1):240...为明晰水肥耦合对炭基质栽培番茄产量品质的提升效应,将生物炭混掺到由酒糟、秸秆等农业废弃物拌制成的基质模块中,设置2个灌溉量(I_(1):100%ET_(c),I_(2):80%ET_(c),ET_(c)为作物蒸发蒸腾量),2个施肥量(N-P_(2)O_(5)-K_(2)O)(F_(1):240-180-200 kg/hm^(2),F2:180-135-150 kg/hm^(2))及基质中4个生物炭添加量(B0:0,B1:1%,B3:3%,B5:5%),共16组处理,研究水肥耦合对炭基质栽培番茄叶面积指数(leaf area index,LAI)、叶绿素相对含量(soil and plant analyzer development,SPAD)、植株养分(全氮、全钾、有机碳)吸收量、化学计量特征(氮钾比、碳氮比)、产量及品质(可溶性固形物含量、维生素C含量、硝酸盐含量、可溶性糖含量、可滴定酸含量、糖酸比)的影响,揭示炭基质栽培番茄产量及品质的关键驱动因子,构建以番茄产量、品质及其关键驱动因子为目标的熵权-TOPSIS多目标综合评价模型,提出水肥与炭基质耦合的最优方案。结果表明:炭基质对番茄LAI、SPAD值、养分吸收量、产量及品质影响显著(P<0.05);在相同灌溉和施肥条件下,炭基质增加了番茄整株钾吸收量、整株碳同化量、产量及维生素C含量,降低了硝酸盐含量;基于结构方程模型,番茄整株碳同化量是产量的关键驱动因子,其增加有助于提高番茄产量,氮钾比是品质的关键驱动因子,其降低有助于改善番茄品质;采用熵权-TOPSIS多目标综合评价模型,筛选出I_(1)F_(2)B_(3)处理是水肥与炭基质耦合的最优方案。研究可为农业废弃物高效利用及高品质果蔬的水肥炭有效管理提供理论依据。展开更多
基金National Natural Science Foundation of China(U2241242)National Key R&D Program of China(2023YFB3812000,2021YFA0716502)。
文摘The accepted doping ion in Ti^(4+)-site of PbZr_(y)Ti_(1–y)O_(3)(PZT)-based piezoelectric ceramics is a well-known method to increase mechanical quality factor(Q_(m)),since the acceptor coupled by oxygen vacancy becomes defect dipole,which prevents the domain rotation.In this field,a serious problem is that generally,Qm decreases as the temperature(T)increases,since the oxygen vacancies are decoupled from the defect dipoles.In this work,Q_(m) of Pb_(0.95)Sr_(0.05)(Zr_(0.53)Ti_(0.47))O_(3)(PSZT)ceramics doped by 0.40%Fe_(2)O_(3)(in mole)abnormally increases as T increases,of which the Qm and piezoelectric coefficient(d_(33))at room temperature and Curie temperature(TC)are 507,292 pC/N,and 345℃,respectively.The maximum Qm of 824 was achieved in the range of 120–160℃,which is 62.52%higher than that at room temperature,while the dynamic piezoelectric constant(d_(31))was just slightly decreased by 3.85%.X-ray diffraction(XRD)and piezoresponse force microscopy results show that the interplanar spacing and the fine domains form as temperature increases,and the thermally stimulated depolarization current shows that the defect dipoles are stable even the temperature up to 240℃.It can be deduced that the aggregation of oxygen vacancies near the fine domains and defect dipole can be stable up to 240℃,which pins domain rotation,resulting in the enhanced Q_(m) with the increasing temperature.These results give a potential path to design high Q_(m) at high temperature.
基金Project(50925829) supported by the National Science Fund for Distinguished Young Scholars of ChinaProject(50908148) supported by the National Natural Science Foundation of ChinaProjects(2009-K4-23,2010-11-33) supported by the Research of Ministry of Housing and Urban Rural Development of China
文摘The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributions of the critical chloride concentration Cc, the chloride diffusion coefficient D, and the surface chloride concentration Cs were determined based on the collected natural exposure data. And the estimation of probability of corrosion initiation considering the coupling effects of influence factors is presented. It is found that the relative humidity and curing time are the most effective factors affecting the probability of corrosion initiation before and after 10 years of exposure time. At the same exposure time, the influence of load-induced crack and stress state on the probability of corrosion initiation is obvious, in which the effect of crack is the most one
基金Projects (U1334201,51525804) supported by the National Natural Science Foundation of ChinaProject (15CXTD0005) supported by the Sichuan Province Youth Science and Technology Innovation Team,China
文摘In a wind-vehicle-bridge(WVB) system,there are various interactions among wind,vehicle and bridge.The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundamental factors,such as mean wind,fluctuating wind,buffeting,rail irregularities,light rail vehicle vibration and bridge stiffness.A long cable-stayed bridge which carries light rail traffic is regarded as a numerical example.Firstly,a finite element model is built for the long cable-stayed bridge.The deck can generally be idealized as three-dimensional spine beam while cables are modeled as truss elements.Vehicles are modeled as mass-spring-damper systems.Rail irregularities and wind fluctuation are simulated in time domain by spectrum representation method.Then,aerodynamic loads on vehicle and bridge deck are measured by section model wind tunnel tests.Eight vertical and torsional flutter derivatives of bridge deck are identified by weighting ensemble least-square method.Finally,dynamic responses of the WVB system are analyzed in a series of cases.The results show that the accelerations of the vehicle are excited by the fluctuating wind and the track irregularity to a great extent.The transverse forces of wheel axles mainly depend on the track irregularity.The displacements of the bridge are predominantly determined by the mean wind and restricted by its stiffness.And the accelerations of the bridge are enlarged after adding the fluctuating wind.
文摘为明晰水肥耦合对炭基质栽培番茄产量品质的提升效应,将生物炭混掺到由酒糟、秸秆等农业废弃物拌制成的基质模块中,设置2个灌溉量(I_(1):100%ET_(c),I_(2):80%ET_(c),ET_(c)为作物蒸发蒸腾量),2个施肥量(N-P_(2)O_(5)-K_(2)O)(F_(1):240-180-200 kg/hm^(2),F2:180-135-150 kg/hm^(2))及基质中4个生物炭添加量(B0:0,B1:1%,B3:3%,B5:5%),共16组处理,研究水肥耦合对炭基质栽培番茄叶面积指数(leaf area index,LAI)、叶绿素相对含量(soil and plant analyzer development,SPAD)、植株养分(全氮、全钾、有机碳)吸收量、化学计量特征(氮钾比、碳氮比)、产量及品质(可溶性固形物含量、维生素C含量、硝酸盐含量、可溶性糖含量、可滴定酸含量、糖酸比)的影响,揭示炭基质栽培番茄产量及品质的关键驱动因子,构建以番茄产量、品质及其关键驱动因子为目标的熵权-TOPSIS多目标综合评价模型,提出水肥与炭基质耦合的最优方案。结果表明:炭基质对番茄LAI、SPAD值、养分吸收量、产量及品质影响显著(P<0.05);在相同灌溉和施肥条件下,炭基质增加了番茄整株钾吸收量、整株碳同化量、产量及维生素C含量,降低了硝酸盐含量;基于结构方程模型,番茄整株碳同化量是产量的关键驱动因子,其增加有助于提高番茄产量,氮钾比是品质的关键驱动因子,其降低有助于改善番茄品质;采用熵权-TOPSIS多目标综合评价模型,筛选出I_(1)F_(2)B_(3)处理是水肥与炭基质耦合的最优方案。研究可为农业废弃物高效利用及高品质果蔬的水肥炭有效管理提供理论依据。
