非对称齿廓齿轮弯曲疲劳强度理论分析与试验

为提高齿轮承载能力设计齿轮两侧压力角不等的非对称渐开线新齿形,推导双压力角非对称齿廓齿轮工作齿侧与非工作齿侧的渐开线齿廓方程和齿根过渡曲线方程,通过迭代计算和优化策略提出非对称齿廓齿轮疲劳强度解析法计算公式。编制生成非对称齿轮齿廓的参数化程序,在此基础上建立非对称齿廓齿轮有限元分析模型。通过解析法对不同压力角组合的非对称齿廓齿轮弯曲应力和危险截面位置计算得出,随着工作齿侧压力角的增大齿根最大弯曲应力逐渐降低,单齿啮合区向齿顶偏移;通过对有限元模型进行计算得出的结果与解析法一致,应用最小二乘法拟合出非对称齿廓齿轮齿根弯曲应力随工作齿侧压力角变化的计算公式。采用数控电火花线切割方法加工制造非对称与标准齿廓齿轮,在高频疲劳试验机上采用双齿脉动加载方法对其进行疲劳强度试验。试验结果表明,非对称齿廓齿轮在相同寿命下比对称齿轮极限载荷提高了50%,非对称齿廓齿轮的应力值变化趋势与前两种方法是一致的

非对称齿廓齿轮弯曲疲劳强度理论分析与试验

为提高齿轮承载能力设计齿轮两侧压力角不等的非对称渐开线新齿形,推导双压力角非对称齿廓齿轮工作齿侧与非工作齿侧的渐开线齿廓方程和齿根过渡曲线方程,通过迭代计算和优化策略提出非对称齿廓齿轮疲劳强度解析法计算公式。编制生成非对称齿轮齿廓的参数化程序,在此基础上建立非对称齿廓齿轮有限元分析模型。通过解析法对不同压力角组合的非对称齿廓齿轮弯曲应力和危险截面位置计算得出,随着工作齿侧压力角的增大齿根最大弯曲应力逐渐降低,单齿啮合区向齿顶偏移;通过对有限元模型进行计算得出的结果与解析法一致,应用最小二乘法拟合出非对称齿廓齿轮齿根弯曲应力随工作齿侧压力角变化的计算公式。采用数控电火花线切割方法加工制造非对称与标准齿廓齿轮,在高频疲劳试验机上采用双齿脉动加载方法对其进行疲劳强度试验。试验结果表明,非对称齿廓齿轮在相同寿命下比对称齿轮极限载荷提高了50%,非对称齿廓齿轮的应力值变化趋势与前两种方法是一致的

非对称齿廓齿轮弯曲疲劳强度理论分析与试验

为提高齿轮承载能力设计齿轮两侧压力角不等的非对称渐开线新齿形,推导双压力角非对称齿廓齿轮工作齿侧与非工作齿侧的渐开线齿廓方程和齿根过渡曲线方程,通过迭代计算和优化策略提出非对称齿廓齿轮疲劳强度解析法计算公式。编制生成非对称齿轮齿廓的参数化程序,在此基础上建立非对称齿廓齿轮有限元分析模型。通过解析法对不同压力角组合的非对称齿廓齿轮弯曲应力和危险截面位置计算得出,随着工作齿侧压力角的增大齿根最大弯曲应力逐渐降低,单齿啮合区向齿顶偏移;通过对有限元模型进行计算得出的结果与解析法一致,应用最小二乘法拟合出非对称齿廓齿轮齿根弯曲应力随工作齿侧压力角变化的计算公式。采用数控电火花线切割方法加工制造非对称与标准齿廓齿轮,在高频疲劳试验机上采用双齿脉动加载方法对其进行疲劳强度试验。试验结果表明,非对称齿廓齿轮在相同寿命下比对称齿轮极限载荷提高了50%,非对称齿廓齿轮的应力值变化趋势与前两种方法是一致的

Studies on Factors of Nasal Absorption of Hirudin

目的:探讨蛋白多肽类中药水蛭素的经鼻吸收特性及其影响因素。方法:用离体蟾蜍上颚黏膜模型,评价水蛭素的鼻纤毛毒性; 采用Valia-Chien水平扩散池实验与在体大鼠鼻腔灌流实验,观察水蛭素鼻腔给药的吸收特性以及药物浓度、pH值等因素对吸收的影响。结果:Valia-Chien水平扩散池实验和在体大鼠鼻腔灌流实验显示水蛭素能够透过鼻黏膜吸收; 介质pH值、药物浓度等因素均能影响水蛭素的吸收,但水蛭素的浓度与渗透系数、吸收速度间线性关系不明显,水蛭素浓度为0.6mg.mL-1时,鼻黏膜吸收较好。结论:水蛭素对离体蟾蜍上颚黏膜纤毛影响较小,并且能透过鼻黏膜吸收; 药物的浓度和介质的pH值对鼻黏膜的吸收均有影响

Effects of volatie oil of Fineleaf schizonepeta herb and Divaricate saposhnikovia root on proinflammatory cytokine expression and regulation

目的：研究荆防挥发油对炎症相关因子表达和调节的影响。方法：用OA和LPS2次打击，建立2次打击急性肺损伤（ALI）模型。荆防挥发油（45．19μL·kg^-1）对大鼠ALI模型支气管上皮细胞间黏附分子CD54，肺组织核因子-κB（NF—κB）p65、支气管上皮细胞中NF—κB p65 mRNA的组织化学观察及统计。结果：荆防挥发油能明显抑制CD54的表达、NF—κB p65的活化及阻止NF—κB p65 mRNA的转录增加。结论：荆防挥发油抑制CD54的表达，减少p65蛋白的合成可能是其抗炎的分子机制之一

Self-Healing Control Design under Actuator Fault Occurrence on Single-rotor Unmanned Helicopters

Actuator faults are inevitable but affect reliability and safety of unmanned helicopters (UHs), especially when there are actuator constraints. In this paper, self-healing control, which is an extended active fault-tolerant control (FTC) method with reference redesign on-line, is proposed to analyze and to guarantee the safety of single-rotor UHs (SUHs) under both actuator faults and constraints. The safety includes body safety and mission safety. More specifically, body safety represents the stability of SUH itself and mission safety represents mission accomplishment with acceptable performance, furthermore, set-point tracking mission is considered. The main contribution of this paper is to analyze and to guarantee the safety of SUHs by solving a set of Linear Matrix Inequalities (LMIs) at one time. The set of LMIs includes saturation compensator design and stability guaranty with a given controller in the absence of actuator constraints, actuator fault compensation analysis, reference reachability analysis and reference redesign. On the other hand, by adding swashplate configuration, SUH model with real actuator outputs as control inputs is constructed which can describe actuator faults more clearly compared to SUH models with nominal control inputs. Finally, the proposed self-healing control method is illustrated by simulation with a nonlinear SUH model

Fault Diagnosis and Fault Tolerant Control Methods for Manned and Unmanned Helicopters: A Literature Review

With the development of unmanned helicopters, the dependability of helicopters have attracted more and more attention of many researchers. In order to deal with these problems, fault diagnosis and fault tolerant control methods were used for manned or unmanned helicopter platforms. This paper presents an overview of the existing works on fault diagnosis, including analytical/model-based, signal processingbased and knowledge-based techniques, and passive/active fault tolerant control approaches for helicopters mainly with single rotor. Before the main part of the review, a short description of fault classification is presented. Compared with the former work, this review contains some in-depth discussion of various fault diagnosis techniques and a survey for fault tolerant control methods