摘要：A multiphysics model for a production scale planar solid oxide fuel cell （SOFC） stack is important for the SOFC technology, but usually requires an unpractical amount of computing resource. The major cause for the huge computing resource requirement is identified as the need to solve the cathode O2 transport and the associated electrochemistry. To overcome the technical obstacle, an analytical model for solving the O2 transport and its coupling with the electrochemistry is derived. The analytical model is used to greatly reduce the numerical mesh complexity of a multiphysics model. Numerical test shows that the analytical approximation is highly accurate and stable. A multiphysics numerical modeling tool taking advantage of the analytical solution is then developed through Fluent@. The numerical efficiency and stability of this modeling tool are further demonstrated by simulating a 30- cell stack with a production scale cell size. Detailed information about the stack performance is revealed and briefly discussed. The multiphysics modeling tool can be used to guide the stack design and select the operating parameters.

摘要：High volumetric power density （VPD） is the basis for the commercial success of micro-tubular solid oxide fuel cells （mtSOFCs）. To find maximal VPD （MVPD） for anode-supported mtSOFC （as-mtSOFC）, the effects of geometric parameters on VPD are analyzed and the anode thickness, tan, and the cathode length, lea, are identified as the key design parameters. Thermo-fluid electrochemical models were built to examine the dependence of the electrical output on the cell parameters. The multiphysics model is validated by reproducing the experimental I-V curves with no adjustable parameters. The optimal lea and the corresponding MVPDs are then determined by the multiphysics model for 20 combinations of rin, the inner tube radius, and tan. And all these optimization are made at 1073.15 K. The results show that： （i） significant performance improvement may be achieved by geometry optimization, （ii） the seemingly high MVPD of 11 and 14 W/cm^3 can be easily realized for as-mtSOFC with single- and double-terminal anode current collection, respectively. Moreover, the variation of the area specific power density with/cac（2 mm, 40 mm） is determined for three representative （tin, tan） combinations. Besides, it is demonstrated that the current output of mtSOFC with proper geometric parameters is comparable to that of planar SOFC.

摘要：Internal reformation of low steam methane fuel is highly beneficial for improving the energy efficiency and reducing the system complexity and cost of solid oxide fuel cells(SOFCs).However,anode coking for the Ni-based anode should be prevented before the technology becomes a reality.A multi-physics fully coupled model is employed to simulate the operations of SOFCs fueled by low steam *** multi-physics model produces I-V relations that are in excellent agreement with the experimental *** multi-physics model and the experimental non-coking current density deduced kinetic carbon activity criterion are used to examine the effect of operating parameters and the anode diffusion barrier layer on the propensity of carbon *** interplays among the fuel utilization ratio,current generation,thickness of the barrier layer and the cell operating voltage are *** is demonstrated that a barrier layer of 400μm thickness is an optimal and safe anode design to achieve high power density and non-coking *** anode structure design can be very useful for the development of high efficiency and low cost SOFC technology.

摘要：通过应变调控二维材料的电学性质和光学性质是设计新型二维电子和光电子器件的重要环节,也是后摩尔时代薄膜器件设计中的关键技术.薄膜CrI_(3)具有铁磁和层间反铁磁的独特性质,但是关于应变调制其电学性质和光学性质的研究未见报道.本文采用高精度杂化密度泛函理论研究了面内单双轴应变对单层CrI_(3)载流子迁移率和介电函数的调控规律,研究结果与已有的实验和理论值符合较好.计算发现:单层CrI_(3)载流子迁移率非常小,均在10 cm^(2)·V^(-1)·s^(-1)以内;与拉伸应变相比,双轴压缩应变可以显著提升迁移率;当双轴压缩应变量增至8%时,沿锯齿方向电子迁移率增至174 cm^(2)·V^(-1)·s^(-1),达到了MoS_(2)水平.可见光区介电函数虚部x(y)方向Ⅰ号吸收峰强度随双轴拉伸应变量增加明显增强,而z方向几乎没有变化;可见光区x(y)和z方向的介电函数虚部曲线开始攀升的起点对应的光子能量均随双轴压缩应变量增加明显减小,且所有吸收峰呈现明显的红移.结果表明,应变可以明显提升单层CrI_(3)的电荷输运性能和可见光区的光学性能.

摘要：依据同时考虑电化学及热平衡耦合的二维模拟软件 ,计算了薄膜钇稳氧化锆 (YSZ)中温燃料电池在不同工作条件下的稳态特性 .通过电流～电压关系参数进行自拟合实验 ,格点选取由平衡收敛性和计算效率而得 ,研究了不同连接体、气流流向设计等工作条件下的温度场 ,给出了不同工作温度下输出功率及电池效率与工作电压的关系 .对温度场的分析表明 :电池板内最高温度及最大温差以并流为最小 ,交叉流为最大 ,并流是最好的气流流向设计 .与以陶瓷材料作连接体相比 ,使用金属连接体能显著减小热应力和电池板内最高温度 ,受益最大的是交叉流 ,其最高温度及最大温差均小于陶瓷连接体的并流设计 .不同的气流流向对于输出功率及电池效率影响很小 ,对并流和金属连接体组合 ,给出了工程设计的燃料分布、电流密度。

摘要：为提高公交专用道利用率,构建了公交-合乘车道(bus-HOV lanes)优化设计的多目标双层规划模型。该模型上层最小化交通总阻抗、公交运营成本和车辆排放;下层考虑非合乘车、合乘车和公交车实现多方式交通网络用户均衡;由快速非支配排序遗传算法求解,其下层由相继平均法和连续权重平均法求解;并使用Nguyen-Dupuis网络验证模型及其求解算法。结果表明:所给算法能有效获得公交-合乘车道设置方案的Pareto最优解集;合理的公交-合乘车道设置方案能有效促进合乘出行;相比不设置公交-合乘车道,全部和部分合乘车进入公交-合乘车道分别使交通总阻抗降低-0.007%~1.088%和0.038%~4.493%,使公交运营成本上升1.057%~3.864%和4.011%~5.611%,使车辆排放减少-7.598%~-1.111%和-0.677%~3.526%;当起讫点(OD)对客流量不低于其临界值,设置公交-合乘车道有利于增加公交车客流量。

摘要：【目的】研究以生物有机肥替代常规化肥对番茄生长及品质的影响,为化肥减施和提高番茄品质、稳定现有产量提供应用和理论基础。【方法】化肥常规用量减施30%、50%,根据不同减施比例配施生物有机肥,小区采用随机区组设计,土样及番茄果实采用随机取样法,测定减施化肥配施生物有机肥对土壤养分转化、及番茄果实营养品质、产量、发病率的影响。【结果】用生物有机肥代替化肥可增加土壤中速效N、P、K的含量,降低土壤pH值和电导率,与常规施肥处理相比,番茄果实总酸提高7.87%,VC含量提高24.95%,可溶性糖提高17.19%,产量与常规持平,差异不显著,番茄脐腐病发病率较常规施肥降低56.83%。【结论】在加工番茄种植中,用生物有机肥代替化肥的施肥方式可以降低化肥的施用量,有利于番茄果实的生长,品质提高,降低番茄脐腐病发病率。

摘要：主要对碳基固体氧化物燃料电池(SOFC)中三传二反的控制方程、不同尺度的不同物理场理论模型以及碳基燃料的重整、催化和硫化等方面进行概括总结。SOFC有可使用氢气、一氧化碳、甲烷和其他的碳氢化合物作为燃料进行电化学反应的燃料灵活性,但使用碳氢燃料需要解决诸如碳基燃料的重整、电极的催化、积碳和硫化等问题。电池内部反应气体的物质输运、电荷输运、能量输运、动量输运和化学及电化学反应状态均可以用偏微分方程来描述。运用这些电化学反应和输运的偏微分方程,结合材料的微观性质,可以建立SOFC的多尺度多物理场模型。通过理论模型研究材料微结构与性质、工作条件、几何构型等参数对电池性能的影响,对SOFC材料组成与电池堆结构进行定量分析和优化设计,可以加速SOFC技术的更快发展。

摘要：《我们班的数学秘密日记》的作者是一名"教数学、写文字"的老师兼科普作家——卢声怡,这本书凝聚着卢老师的教学创意和心得。卢老师在这本书中用班级学习日记的形式,记录了孩子们的数学学习故事,这些故事既包着各种各样的数学知识,又充满趣味。