Fault tolerant flight control - A survey

Nowadays, control systems are involved in nearly all aspects of our lives. They are all around us, but their presence is not always really apparent. They are in our kitchens, in our DVD-players, computers and our cars. They are found in elevators, ships, aircraft and spacecraft. Control systems are present in every industry, they are used to control chemical reactors, distillation columns, and nuclear power plants. They are constantly and inexhaustibly working, making our life more comfortable and more efficient...until the system fails. © 2010 Springer-Verlag Berlin Heidelberg.

Eigenmodes of lined flow ducts with rigid splices

This paper presents an analytic expression for the acoustic eigenmodes of a cylindrical lined duct with rigid axially running splices in the presence of flow. The cylindrical duct is considered to be uniformly lined except for two symmetrically positioned axially running rigid liner splices. An exact analytic expression for the acoustic pressure eigenmodes is given in terms of an azimuthal Fourier sum, with the Fourier coefficients given by a recurrence relation. Since this expression is derived using a Greens function method, the completeness of the expansion is guaranteed. A numerical procedure is described for solving this recurrence relation, which is found to converge exponentially with respect to number of Fourier terms used and is in practice quick to compute; this is then used to give several numerical examples for both uniform and sheared mean flow. An asymptotic expression is derived to directly calculate the pressure eigenmodes for thin splices. This asymptotic expression is shown to be quantitatively accurate for ducts with very thin splices of less than 1 % unlined area and qualitatively helpful for thicker splices of the order of 6 % unlined area. A thin splice is in some cases shown to increase the damping of certain acoustic modes. The influences of thin splices and thin boundary layers are compared and found to be of comparable magnitude for the parameters considered. Trapped modes at the splices are also identified and investigated. © 2011 Cambridge University Press.

液相色谱-离子阱质谱对水华蓝藻提取物中微囊藻毒素的定性研究

本文研究了野外蓝藻水华样品甲醇提取物的液相色谱和电喷雾质谱特征图谱,利用电喷雾离子化-串联质谱(ESI-MSn)离子阱技术对特征图谱中主要微囊藻毒素的分子离子峰进行了二级质谱分析,获得相应的子离子质谱图,并对其进行了结构解析,确定了野外蓝藻水华样品中微囊藻毒素种类,为准确鉴定和分析水华蓝藻中微囊藻毒素提供了基础。

超重环境对斑马鱼仔鱼早期发育和耳石形态学与化学组成的影响

目的本研究以模式动物斑马鱼为研究对象,通过研究超重下鱼体的早期发育和耳石变化,探讨了脊椎动物前庭系统对超重环境的适应机制。方法斑马鱼受精卵在受精后10h分别置于1G和5G重力环境中,观察鱼体发育状态和耳石的形态;使用Zeiss软件比较1G和5G下耳石大小;使用EDAX检测耳石微化学成分含量变化。结果1)斑马鱼从鱼卵向早期仔鱼发育过程中超重环境影响仔鱼发育,耳石形态在初期显著变大(P<0.01),其后耳石变小;2)EDAX检测表明,耳石中S和Sr含量升高,Na和Ca的含量减少;3)出现矢耳石与微耳石融合的现

葛仙米研究进展

科技部科技型中小企业技术创新基金资助(04EFN216600329); 国家星火计划管理项目(2005EA173005)资助

重金属Cd~(2+)、Pb~(2+)和Zn~(2+)对泥鳅DNA损伤的研究

采用单细胞凝胶电泳技术(SCGE),研究重金属Cd2+、Pb2+、Zn2+在不同暴露时间(1—35d)、单一重金属离子不同暴露浓度(0.05mg/L、0.5mg/L、5.0mg/L)或混合重金属离子(Cd2++Pb2+、Cd2++Zn2+、Pb2++Zn2+、Cd2++Pb2++Zn2+)相同浓度(0.5mg/L)条件下对泥鳅肝胰脏细胞核DNA的损伤作用。以带彗尾核DNA百分率和彗尾长度(TL)与核直径(D)比值为指标,探讨DNA损伤级别与处理浓度间的相关性。结果显示,随着处理时间的延长,带彗尾核DNA百

蓝藻有机无机复混肥对几种作物的增效试验

研究了几种专用蓝藻有机无机复混肥,并对农作物进行了田间肥效试验。结果表明,施用蓝藻有机无机复混肥与普通N、P、K复合肥相比较,对烟草,西芹,韭菜,康乃馨等都有增产和改良土壤的效果。烟草试验表明,蓝藻复混肥的施用量以900kg/hm2效果最好,烟草产量、产值、上等烟比例分别比对照增加7.28%,5.04%,19.81%;西芹试验表明,施用蓝藻有机无机复混肥的各处理比对照高,其中以900kg/hm2和1200kg/hm2最高;其次是600kg/hm2;分别比对照高17.1%、16.3%和9.5%;而施用蓝藻有

长江上游特有鱼类受威胁及优先保护顺序的定量分析

根据本课题组1997~2002年野外渔获物调查数据并结合相关文献资料,运用濒危系数、遗传损失系数和物种价值系数对长江上游16种特有鱼类的优先保护顺序进行了定量分析.结果表明,达到一级急切保护的有达氏鲟(Acipenser dabryanus)、鲈鲤(Percocypris pingi)2种;达到二级急切保护的有宜宾鲴(Xenocypris fangi)、齐口裂腹鱼(Schizothorax prenanti)、四川白甲鱼(Onychostoma angustistomata)及云南鲴(Xenocypris

菹草对湖泊沉积物磷状态的影响

武昌野芷湖湾菹草(PotamogetoncrispusL.)生物量较高位置的沉积物显示明显较高的磷吸附指数,以及据Langmuir方程:C/X=C/Xm+K×1/Xm导出的最大吸附量与吸附强度,这一结果在不同时期与不同采样深度均有体现,故提高沉积物磷的吸附能力应为菹草维持水体较低营养水平的重要机制。铁结合态磷是沉积物磷的主要存在形式,吸附能力的提高可由有机质及其与铁的相互作用部分地得到解释。不同时期菹草生物量较高的沉积物表现明显较低的碱性磷酸酶活性与最大反应速度,降低沉积物有机磷的酶促分解速率应为菹草维持

丝藻光合作用无机碳利用研究

丝藻 p H补偿点为 9.2 ,表明其具有较低的 CO2 补偿点 ;不同 p H值下丝藻光合作用放氧速率明显大于理论上从 HCO- 3脱水来的 CO2 供应速率 ,表明其具有利用 HCO- 3的能力 ;未检测到丝藻有胞外碳酸酐酶活性 ,胞内碳酸酐酶的活性随培养液中 CO2 浓度的升高而降低。