最敏感扰动的演变与夏季乌拉尔地区的持续性异常环流

通过数值实验对初始扰动不稳定发展建立异常环流型的过程进行了分析。选择了东亚夏季风异常的１９９１年和１９８５年两个典型年份的平均环流作为基流，以共轭敏感性分析得到的最敏感扰动作为初始扰动，分析其在不同的环流背景下的发展情况。结果说明，１９９１年欧亚地区的基流不稳定性较强，且初始扰动结构有利扰动发展，因而通过能量频散在乌拉尔地区激发扰动并强烈发展，建立起阻塞形势。而１９８５年的扰动在乌拉尔地区形成正涡度距平，不利于阻高的建立。从而导致１９９１年和１９８５年夏季乌拉尔地区几乎相反的异常环流。一系列对比实验说明，异常环流型的建立，不仅依靠能量的频散，更依靠扰动通过正压不稳定过程从基流吸收能量而发展。它既有赖于基流自身的不稳定，又取决于初始扰动的结构以及相对于基流的位置。基流选择了具有特定结构的初始扰动型，只要在有利位置上给予扰动，就能够激发出扰动波列，建立强的持续异常环流型。不论初始波列的位相在一定范围内如何改变，扰动总是倾向于在基流的特定不稳定区域发展。

齿轮接触面最大剪应力最敏感参数的分析

通过理论分析和实例计算,分析了轮齿接触区次表面的应力分布;指出发生在接触区次表面的最大剪应力对接触疲劳磨损起着重要作用;论证了最大剪应力最敏感的参数为最大Hertz应力Pmax及其相关参数。进而完善了齿轮传动接触强度的设计方法。

基于最敏感索力的大跨斜拉桥辅助墩损伤识别研究

在大跨度斜拉桥中,为了在桥梁监测系统内对辅助墩进行快速准确的损伤识别,提出使用最敏感索力对辅助墩损伤识别方法。对于辅助墩损伤识别问题,采用最敏感索力与辅助墩位移进行拟合得到的关系公式,以此通过最敏感索力的变化对辅助墩进行损伤识别。辅助墩竖向位移与最敏感索力关系式的得出,可以运用在桥梁健康监测的损伤研究中,对辅助墩的损伤进行更加快速且准确的识别。

某滑坡滑带土强度参数的敏感性分析

针对#Ⅸ滑坡滑带土强度参数的确定需研究其敏感性问题,以滑坡的某一纵剖面为计算剖面,基于极限平衡法理论,采用不平衡推力传递系数法计算了不同参数取值下滑坡的稳定性,并在强度参数内聚力、内摩擦角和滑带土重度三者中,分别保持某一参数不变,作出其余二者与稳定性系数的关系曲线图,并固定一套参数取值方案,比较各参数随稳定性系数的变化趋势,进而得出敏感性分析结果。结果表明,内摩擦角为影响滑坡稳定性的最敏感因素,重度的敏感性次之,内聚力的敏感性最低。

方案排序对属性值的敏感性分析

多属性决策问题的属性值是决定方案排序的基础。由于许多主观和客观的原因 ,多属性决策问题中属性值的确定常常受到不确定、不精确和易变的因素影响 ,而这些因素将直接影响到决策的结果。从属性值最小变化量出发 ,结合实际案例研究了属性值变化对方案排序的影响及其量化方法 ,采用该方法可以确定出每一个方案对属性值改变的敏感性以及最敏感的方案。

实用光温敏核不育水稻育性稳定性鉴定方法的初步研究Ⅰ．水稻光温敏核不育系育性的光温反应分析

１９９１～１９９４年，在人工气候条件下，通过设宜不同的光温条件对６４个不同类型、不同基因来源的光温敏核不育水稻品系的育性光温反应进行了研究。结果表明：（１）供试材料中未发现典型的光敏雄性不育系，现阶段选育导致不育的起点温度较低的实用型光温敏核不育系是正确的；（２）日均温在２３．８℃以下，光强为４５００１×的低温弱光条件对幼穗发育进度有一定影响，但１５ｄ以内的短期处理影响不明显；（３）不同基因来源或不同类型的光温敏核不育系其育性对温度的最敏感期有差异。

分区总负荷空间上电压稳定安全域的研究

提出了一种高维节点负荷空间到分区总负荷空间的电压稳定安全域降维方法。分区总负荷空间中的电压稳定安全域具有空间维数低,易于描述,便于实现电压稳定在线监测和控制等优点。应用切平面作为该域边界的局部近似,进行电压稳定性的实时监控,从而在保证计算精度的前提下节约计算代价。通过一种迭代搜索算法获取最敏感分区总负荷变化方向,此方向能够辅助运行调度人员进行电压安全监视,同时揭示出电压稳定敏感分区,为安全控制措施的制定及分区总负荷空间中电压稳定安全域的局部可视化表达提供有价值的信息。

大温差地区沥青混合料材料组成因素对路用性能的影响

针对大温差地区沥青混合料材料组成因素(级配类型、沥青标号、石料类型、外加剂掺入方式)的变化对其高低温性能、水稳定性等的影响,分别以动稳定度、低温破坏应变、冻融劈裂强度作为混合料高温稳定性、低温抗裂性及水稳定性的评价指标,通过极差分析和试验验证,证明影响混合料高低温性能因素的敏感性从大到小依次为沥青标号、石料类型、外加剂掺入方式、级配类型,影响水稳性能因素的敏感性从大到小依次为石料类型、外加剂掺入方式、沥青标号、级配类型,且最敏感因素变化对评价指标的影响程度均远超过其他三个因素。最终确定出最优搭配方案,为大温差地区沥青混合料原材料的选择和组成方案提供了依据。

顺序输送润滑油基础油与柴油掺混实验研究

针对润滑油基础油运输成本过高问题,提出了采用管道顺序输送的方式来降低输送成本。基于相邻输送的两种油品顺序输送时物理化学性质越相近混油量越少的原则,提出了抚顺—鲅鱼圈成品油管道应将润滑油基础油和柴油相邻输送。以成品油质量潜力和国家标准中的规定为依据,进行了润滑油基础油和柴油的掺混实验,分析得出HVI150润滑油基础油中掺入0#柴油的最敏感指标(TMSI)为运动粘度,确定了可以掺入0#柴油而又不致使HVI150润滑油基础油指标恶化的最大掺混比例(TLMP)为0.37%。为了降低管道末站接收混油的作业难度,应用IBM SPSS软件对实验数据进行拟合,得出了滑油基础油中掺入0#柴油允许浓度的经验公式,为管道顺序输送润滑油基础油提供了理论依据。

锰金属粉尘最小点火能量实验研究

为了研究锰金属粉尘的最小点火能,在实验室湿度为40~60%、温度为20~32℃的条件下,以粒径范围1.13~138um的锰粉为研究对象,利用1.2L哈特曼实验装置对锰粉进行最小点火能实验。结果表明:在设定锰粉质量为0.6g,喷涂压力为100kPa时,进行不同点火延迟时间对锰粉尘云最小点火能影响实验,锰粉尘云的最小点火能随着点火延迟时间的增加呈现先降低后增大的趋势;在设定质量浓度为0.836g/L及点火延迟时间为100ms时,进行不同喷涂压力对锰粉尘云最小点火能影响实验,锰粉尘云的最小点火能随着喷涂压力的增加呈现先降低后增大的趋势,400kPa为锰粉尘云的最佳分散压力值;进行不同质量浓度的锰粉对锰粉尘云最小点火能影响实验,设定喷涂压力300kPa及点火延迟时间100ms时,锰粉尘云的最小点火能随着粉尘质量浓度的增加呈现先降低后增大的趋势,锰粉云燃烧爆炸的最敏感浓度在1~1.25g/L之间。

217例智力低下儿童病因分析

智力低下(Mental Ketardation,简称MR)病因多,临床表现复杂,不仅鉴别困难,治疗效果也差,严重危害几童生长发育,影响人口素质。根据全国0—14岁儿童调查表明智力低下患者约300万左右,给国家和家庭带来沉重负担,因此正确认识MR的病因,对预防和治疗MR有极其重要的意义。

PARAMETRIC SENSITIVITY AND RUNAWAY IN FIXED BED REACTORS

This paper presents a comprehensive treatment of the parametric sensitivity and runaway in fixed bed reactors with one dimensional pseudo homogeneous dispersion model (ODDM). In this case, we find the existence of multiplicity and determine the runaway criterion through the critical isodisper sion curve. The calculated results indicate when the axial dispersion is relatively small, the impact of the axial dispersion on the parametric sensitivity may be neglected; but when the axial dispersion is large, this impact must be considered.

多跨钢筋混凝土连续梁损伤前后力学变化探究

桥梁在长久运行过程中将遭受到不同程度的损伤,影响桥梁的承载能力及运行安全。连续梁桥在局部出现损伤将会出现内力重分布情况,本文利用Midas软件建立多跨钢筋混凝土连续梁桥的模型,并分别分析了边梁中跨位置在不同损伤宽度下的内力变化规律。得到当损伤宽度上升时,剪力随之上升、正弯矩值下降、挠度值上升。其中挠度变化最为显著,选定挠度为钢筋混凝土连续梁的最敏感识别参数,为后续准确识别出桥梁损伤位置奠定基础。

Social Networks Design of Hospital Facilitators （HFs）＂ An Empirical Study of the Case of Italy

In this paper, the author provides a representation of Italian public hospital facilitators （HFs） （clinics, regional or local community hospitals, and medical centers） by means of different types of networks. Moving from the balance scorecards of HFs, the author has analyzed the representation of those data through the use of the minimum spanning tree （MST） and the planar maximally-filtered graph （PMFG）. This paper firstly examined the amount of information provided by the two networks and then run a sensitivity analysis of the networks by varying the elements of the balance scorecards to be considered. In this way, the author obtained a quite unusual representation of the overall economic situation of Italian HFs. Moreover, the author observed the emergence of patterns which in the author＇s opinion might help policy makers to realize a more efficient allocation of financial resources among the existing HFs.

Mapping the Farming-pastoral Ecotones in China

Conventional farming-pastoral ecotones methods of delineating were not quantitative and could not fully show their spatial distribution. The present paper attempts to develop quantitative methods for mapping farming-pastoral ecotones in China. Nine indicators, related to temperature, precipitation and altitude aspects, were selected to quantify ecological susceptibility of vegetation （crops and forage）. Methods of analytic hierarchy process （AHP） and expert score ranking combined with fuzzy set theory were applied to assign the weight for each indicator and to define the membership functions. The geographic information system （GIS） was used to manage the spatial database and conduct the spatial analysis. According to the spatial calculation of evaluation model integrated with GIS, the ecological susceptibility of vegetation （crops and forage） was mapped. Three different zones, pastoral area, farming-pastoral ecotones and farming area, were classified by spatial cluster analysis and the maximum likelihood classification for the numeric map of vegetation ecological susceptibility by GIS. This map was validated by the economic statistical result based on the ratio of the output value from animal husbandry in total output value of agriculture by the National Bureau of Statistics in China, indicating that the mapping of the farming-pastoral ecotones may be accepted.

Application of the Conditional Nonlinear Optimal Perturbations Method in a Theoretical Grassland Ecosystem

Using a simplified nonlinearly theoretical grassland ecosystem proposed by Zeng et al.,we study the sensitivity and nonlinear instability of the grassland ecosystem to finiteamplitude initial perturbations with the approach of conditional nonlinear optimal perturbation （CNOP）.The results show that the linearly stable grassland （desert or latent desert） states can turn to be nonlinearly unstable with finite amplitude initial perturbations.When the precipitation is between the two bifurcation points,a large enough finite amplitude initial perturbation can induce a transition between the grassland statethe desert state or the latent desert.

Crack detection using integrated signals from dynamic responses of girder bridges

An innovative approach for the identification of cracks from the dynamic responses of girder bridges was proposed.One of the key steps of the approach was to transform the dynamical responses into the equivalent static quantities by integrating the excitation and response signals over time.A sliding-window least-squares curve fitting technique was then utilized to fit a cubic curve for a short segment of the girder.The moment coefficient of the cubic curve can be used to detect the locations of multiple cracks along a girder bridge.To validate the proposed method,prismatic girder bridges with multiple cracks of various depths were analyzed.Sensitivity analysis was conducted on various effects of crack depth,moving window width,noise level,bridge discretization,and load condition.Numerical results demonstrate that the proposed method can accurately detect cracks in a simply-supported or continuous girder bridges,the five-point equally weighted algorithm is recommended for practical applications,the spacing of two discernable cracks is equal to the window length,and the identified results are insensitive to noise due to integration of the initial data.

Novel Method for Optimal Location of STATCOM in Distribution Systems Using Sensitivity Analysis by DIgSILENT Software

In this paper a new method has been proposed to decide optimal placement and best sizing of STATCOM （static synchronous compensator）. The best place of STATCOM is found using the sensitivity analysis and optimum sizing of STATCOM is managed using the genetic algorithm. The average model can account for the high-frequency effects and power electronic losses, and more accurately predict the active and reactive power outputs of the STATCOM. This paper employs the DIgSILENT simulator and DPL （DIgSILENT programming language） as a programming tool of the DIgSILENT to show the validity of the proposed method. The effectiveness of suggested approach has been tested on part of the distribution network of Iran, Khoramdarreh city in Zanjan province.

Prediction of the Maximum Flow by the Model SASIS： Sensibility to the Empirical Parameters of the Shape of the Furrow

The model developed in this research presents effective mechanisms in simulations of a discharge strip understood between the minimum and the maximum allowable values, aiming to determine the relationship between discharge and water application efficiency, deep percolation and runoff rates, and consequently to optimize the performance of the furrow irrigation systems with continuous flow. The flow applied in each furrow must be adapted to the length, to the field slope and to the nature of the ground. The authors studied the maximum non erosive flow （Q,,,~）, in function of parameters obtained from the dimensions of the furrow, being Pl and/92, respectively, the linear and exponential parameters of the potential functions that described the relationship between the area of the cross section of flow （or wetted perimeter） and height of flow; in this way, the multiplicative effect of,01 on the area of the cross section of flow is linear, while ,02 is exponential. It verified a conjugated effect of,or and p20n the value of Q,,~. The results of this research point out for the importance of having an estimate of the parameters of the geometry of the cross section of flow （,01 and ,02） the most precise as possible, being known that the dimensions of this section can result in impracticable values of Qmax, outside of the acceptable strip in the literature, that is from 1.2 to 4.0 L.sl. This sensibility analysis was also of great benefit to create an interface in the software SASIS, capable to guide the user of this tool in the input of appropriate values for ,01 and P2 to the process of simulation of the irrigation for furrow with continuous flow and of the optimization of its performance.

Nasal carriage of Streptococcus pneumoniae among children in Beijing

Objective To investigate the antimicrobial susceptibility of Streptococcus pneumoniae carried in the nose among children in Beijing and the distribution of serotypes,and to analyze the risk factors for nasal carriage of penicillin non-susceptible S.pneumoniae.Methods A disk diffusion test was applied to detect the antimicrobial susceptibilities of S.pneumoniae to erythromycin,trimethoprim-sulfamethoxazole,chloramphenicol and tetracycline.The E test was applied to determine the minimal inhibitory concentrations of penicillin,cefuroxime,cefotaxime,augmentin and imipenem.S.pneumoniae isolates were serotyped by the Quellung reaction.Results S.pneumoniae that was resistant to penicillin or cefuroxime was not found,but S.pneumoniae intermediate resistant to penicillin and cefuroxime accounted for 8.2% and 2.1%,respectively.All of the isolates were susceptible to cefotaxime,augmentin and imipenem.S.pneumonia that was resistant to erythromycin,trimethoprim-sulfamethoxazole and tetracycline were extremely numerous,accounting for 72%,70% and 79%,respectively.Five serotypes(19,6,14,23,17)accounted for 54.7%,and nontypables accounted for 20.6% of all the S.pneumoniae.Previous history of otitis media was a risk factor we found for nasal carriage of penicillin non-susceptible S.pneumoniae.Conclusions Continued surveillance of the antimicrobial susceptibilities of S.pneumoniae is necessary.A larger scale investigation is needed to identify if the 7 or 9-valent conjugate pneumococcal vaccine is appropriate for Chinese children.