信息缺失时基于HMM的故障诊断方法

在突发事件导致的事故中,状态监测与故障诊断系统的研究对象已经发生很大的变化,常规设计的状态监测与故障诊断系统往往很难满足要求.文章针对信息缺失提出了一种新的状态监测与故障诊断方法.该方法基于HMM模型的似然率计算过程,提出在发生信息缺失时,对缺失信号依据各模型采用最大似然率填充的方式进行故障诊断,并通过实际数据的测试实验对该方法进行了验证.验证结果表明,信号缺失时依据各模型采用最大似然率填充的方式进行故障诊断的方法是有效的.     

网络环境下高职院学生开放式考核管理初探

针对新时期网络环境下的高职院学生,采取有效的日常考核手段成为学生管理的重点.文章对高职院学生日常考核管理的现状和成因进行分析,提出运用网络手段进行开放式考核的论点,并对其产生的效果进行论证.     

Overview of flowline bundle technology from concept selection to offshore installation

Flowline bundle system consisting of carrier pipe,sleeve pipe and internal flowlines offers innovative solution for the infield transportation of oil and gas. Due to its features,flowline bundle offers a couple of advantages over conventional flowline in particular for cases where multi-flowlines and high thermal performance is of great interest. The main benefits and advantages of such system include excellent thermal performance to prevent wax formation and hydrates,multiple bundled flowlines,mechanical and corrosion protection,potential reuse, etc. With the developments of offshore oil and gas industries,more and more hydrocarbon resources are being explored and discovered from shallow to deep water. Pipeline bundle system can be a smart solution for certain applications,which can be safe and cost effective solution. The objective of this paper is to overview pipeline bundle technology,outline detailed engineering design issue and procedure. Focus is given to its potential application in offshore for infield transportation. Engineering design principles and procedures for pipeline bundle system are highlighted. Construction methods of flowline bundle onshore are reviewed. Offshore towing and installation of pipeline bundle procedure is outlined.     

建筑施工进度的管理方法探讨

建设项目的进度管理,是施工管理中不可或缺的重要一环,有着特殊的重要性与作用。本文从现场施工管理的角度,阐述了施工进度管理在项目管理中的作用,并对如何做好施工进度进行了比较分析。     

一类具有吸收效应的时滞病原体免疫模型(英文)

研究了一类具有吸收效应的时滞病原体免疫模型.推导出系统的基本再生数与免疫再生数的表达式.通过运用Lyapunov泛函方法,分别给出了系统的无病平衡点、无免疫平衡点及地方病平衡点全局渐近稳定的条件.     

Magnetoacoustic tomography with current injection

Magnetoacoustic tomography combines the advantages of electrical impedance tomography with sonography.It can reconstruct conductivity images of biological tissue with high spatial resolution and high contrast.In addition,magnetoacoustic tomography is a new nondestructive functional imaging technology,with which we can realize the early diagnosis of human diseases.In this paper,through theory analysis we deduced the analytical formula of acoustic pressure.Computer simulation and experimental studies on magnetoacoustic tomography with current injection(MAT-CI)were made,and a copper ring was used as the model for the simulation and experiment.Experimental setup and methods are introduced,and the acoustic signals and the image of a metal object by means of MAT-CI are presented.Results of the simulation and experiment were in a good agreement.The reconstructed image of an acoustic source can reflect the conductivity information of a sample.The conductivity distribution of a sample can be obtained by means of MAT-CI.The results provide foundations of study on a model with complex conductivity distribution and tissues for MAT-CI.     

Development of DArT markers for a linkage map of flue-cured tobacco

Tobacco(Nicotiana tabacum) is one of the most economically important nonfood crops,and flue-cured tobacco accounts for approximately 80% of world tobacco production.An extremely narrow genetic diversity in the tobacco pool has led to a low efficiency of PCR-based molecular markers(such as AFLP and SSR).Diversity Arrays Technology(DArT) is a high-throughput hybridisation-based marker system that has been developed in many plants including wheat,which,like tobacco,has a complex genome.In this study,we developed a tobacco DArT chip that included 7680 representative sequence tags based on typical tobacco accessions.The 1076 DArT markers of flue-cured tobacco were identified and most(82.1%) of their polymorphism information contents(PICs) were greater than 0.4.An integrated linkage map that included 851 markers(238 DArT and 613 SSR),which is the highest density map of flue-cured tobacco to date,was constructed.This chip-based DArT system provides an alternative in high-throughput marker genotyping for tobacco.     

宁夏地区水泥强度富余系数R_c研究

结合宁夏地区实际特点,选取不同来源不同等级水泥测试其实际强度,在保证可靠性基础上计算水泥强度富余系数范围.所得结果可为宁夏地区混凝土生产过程中减少水泥用量、降低成本和提高性能提供理论依据.     

纤维过滤介质在容尘阶段的非稳态过滤效率

基于黏性牛顿流体的N-S方程,从一般控制方程的通用形式,结合纤维过滤介质的积尘填充率与粉尘颗粒或气溶胶微粒沉积量,推导出纤维多孔过滤介质内粒子浓度分布的非线性微分方程.分析了过滤效率经验公式中无量纲参数之间的内在联系及其对纤维滤料在容尘阶段过滤效率的影响,利用非线性回归方法拟合出纤维过滤介质的非稳态过滤效率经验公式.结果表明:微粒的Re数均小于1,即空气的流动均处于斯托克斯区域,同时其流动状态为层流;计算得到的拦截参数为0.086～0.559.根据实验结果拟合的纤维滤料在容尘阶段的过滤效率经验公式适用于St小于1的场合.     

溶氧水平对梭鱼幼鱼能量代谢与氧化应激的影响

为分析低氧胁迫对梭鱼（Liza haematocheila）幼鱼能量代谢与氧化应激的影响,选择体重为6～10g的梭鱼,在溶氧水平从7.18 mg/L降至0.60mg/L过程中测定其耗氧率和排氨率,计算幼鱼相对应的氧氮原子比（O∶ 2 N）;又在溶氧水平大于6.0mg/L、4.5 mg/L、3.0 mg/L、1.5 mg/L、0.5 mg/L时,分别测定幼鱼肌肉和肝脏组织中的乳酸（LD）含量、过氧化物歧化酶（SOD）活力、总抗氧化能力（T-AOC）、抗超氧阴离子活力（ASOR）、丙二醛（MDA）含量.结果显示,随着溶氧水平的下降,梭鱼的耗氧率和排氨率总体呈降低趋势,氧氮原子的比值在溶氧水平3.23～1.92 mg/L时达到最大,在溶氧水平1.03～1.60 mg/L时达到最小;溶氧水平为6.15mg/L时,肝脏中LD、SOD、T-AOC、ASOR、MDA均显著大于其它溶氧水平下的相应指标（P＜0.05）.溶氧水平下降过程中,肌肉组织中的SOD、MDA、TAOC差异不显著（P＞0.05）,溶氧水平在0.5 mg/L时,LD显著高于其它组（P＜0.05）.这表明,梭鱼能通过降低耗氧率和排氨率、改变代谢底物和提高肌肉、肝脏组织无氧代谢能力等方式,达到新陈代谢的平衡,以适应低氧生活.