用近红外无损肌氧及运动心率检测技术评定100m极量强度运动对心脏冲击影响

利用连续双波长近红外光技术测量肌肉中血红蛋白含氧量的变化情况,同时应用运动心率无线实时采集设备,设计了检测实时肌肉组织血氧含量和瞬时心率实验方案,对6名健康男性进行了100 m跑同步实测实验。实验表明,肌肉组织氧合血红蛋白浓度在100 m跑结束后继续降低,达到最低值的时刻滞后于运动结束时刻的时间为(6.65±1.10)s;心率则在运动结束后继续上升,达到最高值的时刻滞后于运动结束时刻的时间为(8.00±1.57)s。这些结果显示了双波长近红外光组织氧测试技术和运动心率无线实时采集系统能够正确检测极量强度运动时的血氧参数和心率,揭示了极量强度运动过程中肌肉中氧运输与消耗的过程及其与心率之间的动力学特征。     

Closed Unstretchable Knotless Ribbons and the Wunderlich Functional

In 1962, Wunderlich published the article “On a developable Möbius band,” in which he attempted to determine the equilibrium shape of a free standing Möbius band. In line with Sadowsky’s pioneering works on Möbius bands of infinitesimal width, Wunderlich used an energy minimization principle, which asserts that the equilibrium shape of the Möbius band has the lowest bending energy among all possible shapes of the band. By using the developability of the band, Wunderlich reduced the bending energy from a surface integral to a line integral without assuming that the width of the band is small. Although Wunderlich did not completely succeed in determining the equilibrium shape of the Möbius band, his dimensionally reduced energy integral is arguably one of the most important developments in the field. In this work, we provide a rigorous justification of the validity of the Wunderlich integral and fully formulate the energy minimization problem associated with finding the equilibrium shapes of closed bands, including both orientable and nonorientable bands with arbitrary number of twists. This includes characterizing the function space of the energy functional, dealing with the isometry and local injectivity constraints, and deriving the Euler–Lagrange equations. Special attention is given to connecting edge conditions, regularity properties of the deformed bands, determination of the parameter space needed to ensure that the deformation is surjective, reduction in isometry constraints, and deriving matching conditions and jump conditions associated with the Euler–Lagrange equations.

     

侧向局部加热对流的周期性

通过流体力学方程组的数值模拟,研究了侧向局部加热条件下Prandtl数Pr=0.0272时流体对流的周期性.结果表明:随着Grashof数Gr的增加,对流按稳态对流、单局部周期对流、双局部周期对流、准周期对流的顺序发展.当Gr<3.6×103时,对流为稳态;在3.6×103相似文献   

考虑策略型消费者和退货的零售商降价促销决策研究

基于零售商降价促销问题,引入策略型消费者,考虑到异质性消费者有可能对商品不满意,构建两期决策模型,旨在从退货和价格路径优化两方面提高零售商利润。研究给出(不)允许退货时,零售商面对策略型消费者的定价建议,指出零售商制定价格要在一定程度上参考商品类型。订货量相同时,给出策略型消费者降低零售商的期望利润的条件;面对短视型或者策略型消费者时,允许退货可在特定条件下提升零售商利润。消费者退货成本越高,对策略型消费者消极影响的抑制作用越明显,零售商的利润增长越显著。最后,通过数值算例分析了在两种退货决策以及不同退货成本下产品类型对零售商定价的影响,以及退货措施对策略型消费者消极影响的作用。     

关于“评测指标权重确定的结构熵权法”的注记

本文基于文献[1]所提出的观点,根据熵理论和德尔斐专家调查法,对文献[1]所提出的方法进行了改进,得到了改进的结构熵权法,并运用此方法对环保项目指标进行权重确定,同时与经典的德尔斐专家调查法确定的权重进行比较,并对二者的差异作出了合理解释。     

基于可用度的复杂结构装备检修时机决策模型

为最大限度地提高装备的可用度水平,检修工作十分必要,而检修时机的确定即成为一个重要的决策问题。对于复杂结构装备,组成部件的数量、寿命分布及对应的维修策略等都是可用度的影响因素。在采取预防性维修和修复性维修相结合策略的基础上,推导出了单装备任务周期内可用度关于检修时机的表达式,以此获得了装备群系统的检修时机决策模型,并充分考虑了部件工作年龄的影响。通过实例分析,验证了模型的合理性和实用性。     

基于空间价格均衡理论的二层供应链网络模型研究

利用空间价格均衡理论和两层规划理论研究了由供应商和需求市场构成的两级供应链网络,构建了具有变分不等式约束形式的两层供应链网络模型,该模型既能反映同层成员间的非合作博弈关系,又能反映上下层之间的所具有的均衡性,通过算例分别分析了决策函数在对称和不对称情况下的均衡解,并给出了经济解释。     

Eu掺杂ZnO薄膜光学性能的研究

采用射频磁控溅射技术在硅衬底上制备了ZnO∶Eu3+薄膜,利用X射线衍射仪和荧光光谱仪对样品的微观结构及光学性能进行了表征。结果表明:ZnO∶Eu3+薄膜具有六角纤锌矿结构;在基质激子的激发下,ZnO∶Eu3+有很强的Eu红光特征发射且强度随着ZnO缺陷的增加而增加,激发光谱中出现ZnO的带间激发与纯Eu2O3的直接激发光谱,证明了ZnO和Eu3+之间存在能量转移;荧光衰减谱也进一步证明Eu3+依赖ZnO缺陷的能量转移过程,Eu3+的衰减时间随着ZnO缺陷的衰减时间的变化而变化,促进能量传递的一个有效的方法就是在ZnO基质中确定一个合适的缺陷中心。     

新型10-取代小檗碱衍生物的合成

2-羟基-3-甲氧基苯甲醛在酸性条件下脱除甲基制得2,3-二羟基苯甲醛（2）;在不同碱作用下,2与卤代烷烃选择性反应生成邻、间烷氧基单取代中间体（3和4）,经二次烷基化反应制得2-甲氧基-3-烷氧基、2-烷氧基-3-丁氧基苯甲醛（5a~5f）; 5a~5f与3,4-亚甲二氧基苯乙胺经脱水缩合生成席夫碱中间体,再依次经硼氢化钠还原生成胺,并与乙二醛水溶液发生双重环合反应,合成了一系列10-位非甲基取代的小檗碱衍生物（9a~9f）,其中5b~5e和9a~9f为新化合物,其结构经¹H NMR、¹³C NMR和HR-MS(ESI)表征。     

Blue-to-Orange Tunable Luminescence from Europium Doped Yttrium--Silicon--Oxide--Nitride Phosphors

Europium-doped yttrium-silicon-oxide-nitride phosphors are synthesized by carbothermal reduction and nitridation method. The crystal structure of the phosphors changed gradually from oxide Y2Si2O7 to nitride YSi3N5 state with increasing dosage of Si3N4 and carbon powder. The Y2Si2O7：Eu phosphor shows a blue emission at 465 nm with 300 nm excitation and a characteristic red emission of Eu^3＋ at 612 nm with 230 nm excitation. The YSi3N5：EU phosphor shows a broad emission band centred at 595nm with some sharp peaks of Eu^3＋ with 325nm excitation. The absorption of the studied phosphors increases from 450 to 700hm with an increment in nitrogen content. Blue-to-orange tunable luminescence is observed with 390 nm excitation.