非酒精脂肪性肝病患者中医健康管理行为意向模型构建

目的 探究非酒精脂肪性肝病(NAFLD)患者参与中医健康管理的影响因素,为优化中医健康管理策略、提高患者参与度及依从性提供依据。方法 基于计划行为理论建立NAFLD患者中医健康管理行为意向模型,采用自行编制的调查问卷对2018年1~6月湖北省中医院体检中心及肝病门诊的NAFLD患者进行问卷调查,使用AMOS 22.0软件进行模型拟合、分析和评价。结果 NAFLD患者中医健康管理行为意向模型与样本数据的适配度良好。行为态度、主观规范和知觉行为控制对行为意向的效应值分别为0.22、0.21和0.21,差异均有统计学意义(均P <0.05)。结论 计划行为理论适用于解释NAFLD患者的中医健康管理意向,在依据计划行为理论提升患者行为意向时,应树立积极的行为态度、重视主观规范的作用、改善知觉行为控制,共同提升患者的行为意向,促进NAFLD中医健康管理的发展与完善。

基于思维导图预防患者跌倒工作坊培训探讨

目的探讨基于思维导图的工作坊模式在临床护士预防患者跌倒培训中的应用效果。方法2018年8月-2018年10月采用方便抽样法对40名临床护士实施思维导图的工作坊培训模式,采用问卷调查培训前、后护士的跌倒防范知识水平及培训后学员对工作坊教学模式的满意度评价。通过配对样本t检验、描述性统计学分析对数据进行分析。结果培训后学员跌倒防范测试成绩(17.98±1.51)分,较培训前(15.03±1.73)分明显提高,两者之间的差异具有统计学意义(P<0.01),学员对教学模式的评价较高满意度均在90%及以上。结论基于思维导图的工作坊教学模式可提高临床护士预防患者跌倒知识水平,提升教学培训效果,有助于保障临床护理安全。

Fluid-structure Interaction Analysis and Lifetime Estimation of a Natural Gas Pipeline Centrifugal Compressor under Near-choke and Near-surge Conditions

Up to present, there have been no studies concerning the application of fluid-structure interaction（FSI） analysis to the lifetime estimation of multi-stage centrifugal compressors under dangerous unsteady aerodynamic excitations. In this paper, computational fluid dynamics（CFD） simulations of a three-stage natural gas pipeline centrifugal compressor are performed under near-choke and near-surge conditions, and the unsteady aerodynamic pressure acting on impeller blades are obtained. Then computational structural dynamics（CSD） analysis is conducted through a one-way coupling FSI model to predict alternating stresses in impeller blades. Finally, the compressor lifetime is estimated using the nominal stress approach. The FSI results show that the impellers of latter stages suffer larger fluctuation stresses but smaller mean stresses than those at preceding stages under near-choke and near-surge conditions. The most dangerous position in the compressor is found to be located near the leading edge of the last-stage impeller blade. Compressor lifetime estimation shows that the investigated compressor can run up to 102.7 h under the near-choke condition and 200.2 h under the near-surge condition. This study is expected to provide a scientific guidance for the operation safety of natural gas pipeline centrifugal compressors.

涡轮式砂磨机数值模拟与改进

采用计算流体动力学(CFD)方法对涡轮式砂磨机进行单相流场数值模拟,改进其涡轮结构,分析涡轮改进前、后以及不同涡轮转速对砂磨机内部流场和研磨特性带来的影响。结果表明:改进后的涡轮可以使砂磨机内部流体拥有更大的流速,提升研磨介质中颗粒间的碰撞频率与能量,并且增大流体近壁侧的速度梯度,整体研磨强度与最大研磨强度都有所提升;在一定范围内提升涡轮转速,砂磨机内流场特征并不会改变,其研磨强度的提升同涡轮转速呈正相关。

Robust Design Optimization Method for Centrifugal Impellers under Surface Roughness Uncertainties Due to Blade Fouling

Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression（SVR） metamodel is combined with the Monte Carlo simulation（MCS） method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

A Rapid and Automatic Optimal Design Method for Six-Stage Axial-Flow Industry Compressor

Existing aerodynamic design systems for multi-stage axial-flow compressor suffer from several limitations,such as experience dependent models and time costly simulations.Few attempts,however,have been devoted to the rapid and automatic optimization of aerodynamic performance at the preliminary design phase,which plays a crucial role in the final aerodynamic performance.In this work,a rapid and automatic aerodynamic optimal design method is developed for the multi-stage axial-flow compressor based on one-dimensional meanline design method,radial-equilibrium equation and genetic algorithm.The one-dimensional performance prediction model includes some popular empirical correlations to calculate the flow loss,incidence angle,deviation angle and flow blockage.The radial-equilibrium equation is solved to obtain the spanwise distribution of aerodynamic and thermodynamic parameters at the inlet and outlet of each blade row.The genetic algorithm is used for an automatic search of the global optimal compressor configuration aiming at maximizing the design efficiency.The developed method is illustrated with the aerodynamic optimal design of a 6-stage axial-flow industry compressor and verified by computational fluid dynamics simulations.The results show that the developed method is capable of improving effectively the design efficiency and predicting accurately the aerodynamic performance of the 6-stage axial-flow industry compressor in a few minutes.This work is of scientific significance to improve the axial-flow compressor design system and of engineering importance to release the designers from the heavy experience dependence especially at the preliminary design phase.