老年慢性心力衰竭病人衰弱综合征临床特点及相关危险因素分析

目的:分析老年慢性心力衰竭(CHF)病人衰弱综合征临床特征及相关危险因素。方法:选择CHF病人为研究对象,采用调查问卷及查阅病历资料的方法,分析184例病人衰弱综合征临床特征及相关危险因素。结果:184例老年CHF病人中,发生衰弱综合征66例,发生率35.87%(66/184)。衰弱综合征组女性、年龄、初中及以下文化程度、独居、美国纽约心脏病协会分级(NYHA分级)(Ⅲ级+Ⅳ级)、合并疾病(2~7种)、肌酐高于非衰弱综合征组,血红蛋白、白蛋白、左心室射血分数低于非衰弱综合征组(P<0.05~P<0.01);多因素logistic回归分析结果显示,年龄、合并疾病数量、血红蛋白、肌酐、左心室射血分数是老年CHF病人衰弱综合征的独立影响因素(P<0.05~P<0.01)。结论:老年CHF病人伴发衰弱综合征风险较高,受多种因素影响,应加强对高龄、合并多种疾病等老年CHF病人的管理干预,以减少衰弱综合征的发生。

Derivation and application of time step model in solidification process simulation

The heat transfer during the casting solidification process includes the heat radiation of the high temperature casting and the mold,the heat convection between the casting and the mold,and the heat conduction inside the casting and from the casting to the mold. In this paper,a formula of time step in simulation of solidification is derived,considering the heat radiation,convection and conduction based on the conservation of energy. The different heat transfer conditions between the conventional sand casting and the permanent mold casting are taken into account in this formula. The characteristics of heat transfer in the interior and surface of the casting are also considered. The numerical experiments show that this formula can avoid computational dispersion,and improve the computational efficiency by about 20% in the simulation of solidification process.

2A14铝合金轮毂模锻件开裂原因及控制措施

飞机轮毂是飞机承力关键件之一。本文主要分析轮毂锻件断裂的原因,并提出控制措施。采用金相显微镜、SEM、拉伸试验机和布氏硬度计等对2A14铝合金轮毂锻件断裂位置进行宏观和微观组织观察、能谱及成分分析、力学性能检测。结果表明:2A14铝合金轮毂锻件产生裂纹的主要原因是锻件在固溶淬火过程中产生的残余应力和机械加工过程中切削应力累积引起的应力开裂。提出了自然时效和去应力低温时效两种降低锻件残余应力的方法,防止了锻件开裂,提高了产品性能。