An improved shear lag model for predicting stress distribution in hybrid fiber reinforced rubber composites

An improved micromechanical shear lag model, which considers the interphase and bonded fiber end, is developed to investigate the load-carrying characteristics and stress profiles in hybrid aramid/sepiolite fiber reinforced rubber composites. The properties of the equivalent matrix, which is combination of sepiolite fiber and rubber matrix, are determined by Mori-Tanaka method. The axial and shear stresses at the fiber end are resolved by the imaginary fiber technique. The results obtained from the improved model show the tensile stress has a maximal at the real fiber center and the interfacial shear stress has a maximal at the end of the real fiber. Comparing with the results from Tsai’s model, the improved model has a better agreement with the numerical simualtion results. The effects of the imaginary fiber length on the stress transfer are analyzed and the results show that the effects can be ignored when the imaginary fiber length is greater than twice of the fiber radius. The effects of interphase modulus and thickness on the maximal axial and shear stresses are discussed. The results show that the interphase modulus and thickness of about 106.3 MPa and 0.2 μm are optimal to prevent interfacial debonding and improve the strength of hybrid fiber reinforced rubber composites.     

独蒜兰离体快繁技术研究

以野生独蒜兰成熟未开裂的蒴果为外植体,对独蒜兰离体快繁技术进行研究。结果显示:用清水冲洗后再用75%酒精消毒30s,0.1%升汞消毒10min,污染率低至26%。培养基VW+0.005mg·L^-1TDZ+0.3mg·L^-1NAA适宜于独蒜兰的种子萌发培养,在该培养基中独蒜兰种子的萌发率为39.3%;适宜独蒜兰芽增殖的培养基为VW+1.0mg·L^-16-BA+0.2mg·L^-1NAA,在该培养基中独蒜兰芽的增殖系数为7.6;在VW+0.2mg·L^-1NAA+0.2mg·L^-1IBA+0.3g·L^-1活性炭的培养基上,独蒜兰的生根率为92%。独蒜兰组织培养技术体系的建立,对于解决其生产用苗紧缺以及遗传改良有着重要的理论价值及实践意义。     

浅议南水北调西线工程 促进甘肃经济社会发展

通过对我国水资源少、南北水资源时空分布不均衡等方面的分析,指出我国南水北调西线工程的利弊关系。建议从增加甘肃省黄河可供水量的分配限额、实施河西走廊调水工程、开辟南水西调新线工程、治理水患、从西南调水等方面来调整我国水资源分配,以缓解水资源分布不均衡的现状,从而解决我国沙尘暴、洪涝灾害严重等问题。特别是可以缓解甘肃省极度干旱缺水的矛盾,对甘肃经济发展,特别是林业经济发展将有非凡的现实意义和战略意义。     

石屏县松纵坑切梢小蠹的发生现状及防治对策

针对松纵坑切梢小蠹在石屏的发生现状及趋势,结合石屏县采取的防治措施及效果进行比较分析,总结出适合石屏县特点的综合防治技术措施。     

核桃专用生物-有机-无机复混肥对核桃种植的影响

目前核桃专用肥以复混肥搭配有机肥为主,肥料利用率较低,且会造成肥料浪费,增加施肥成本;本研究结合核桃需肥规律和核桃主产区土壤养分情况,针对核桃专用肥的施用现状在云南核桃主产区进行生物-有机-无机复混肥的应用研究,旨在提高肥料利用率、减少肥料施用量和提高核桃产区土壤微生物活性;在肥料施用期间检测土壤微生物情况以及功能菌株...     

果蔬热物性的研究与比较

利用测量热物性的实验装置与计算模型,对多种果蔬进行实验数据的研究比较,找出较为准确的方法,通过研究发现式(2)(6)和式(17)较好,并为今后果蔬热物性的研究提供理论基础.     

Mechanical amplification of insect campaniform sensilla

Research on the mechanical amplification function of natural organisms presents a bio-inspired approach for the future design of strain sensors to be embedded in engineering bodies. By the observation under FTEM, the micromorphology of chafer cuticle is found as follows：insect cuticle is a typical example of a natural composite plate with cross-fiber laminates reinforced,on the surface of which a series of trichopores with diameter of 50~70 μm are distributed in the space of 40~50 μm. This microstructure is characterized as a composite plate with holes with cross-fiber laminates reinforced. The stress amplification factor that helps to improve sensilla’s sensitivity is achieved as 2.424 by finite element method and weighted average method. Furthermore continuous helicoidal fibers around the channel under trichopore are found,which resist stress concentration from every orientation and protect the gland and body wall.     

Real Time Monitoring System of Drilling State in the Different Places Based on Internet

On the basis of the Real Time Multi-parameter Monitoring System of Drilling Engineering, a new Internet-based Real Time Monitoring System of Drilling State in Different Places is developed. This system enables long-distance monitoring on the drilling field through the Internet. In the different places the basic data can be obtained from the drilling field, in this way the technology resource and expert resource in the different places can be taken full advantage to resolve the problem of the weak technology of the drilling team, and realize the long distance monitoring, long distance direction, and long-distance management. This system makes use of the popular network technology and data management technology, and adopts the Asp and Java to settle the key technology problem of the real time transmission and real time display.     

Nonlinear Predictive Control of Small Sag cable with Axial Displacement

An approach for the control of a small sag cable is presented.The approach is based on a nonlinear predictive control scheme that determines the required axial displacement input so that the predicted response match the desired Results.It is accomplished by minimizing the norm squared local errors between the predicted and desired values.Finally simulation results that use the new control strategy to demonstrate the effective are show.