浅谈防火墙在网络安全中的作用

本文介绍网络安全相关技术特性。     

连续刚构箱梁剪力滞效应分析

以靖远黄河大桥这一五跨连续刚构箱梁桥为工程背景,运用当量截面法计算靖远桥的剪力滞系数。分析其简化计算,将结果与ANSYS分析结果进行比较。     

聚合物熔体挤出流动中的弹性行为

研究了聚合物熔体挤出过程中出口压力降ΔＰｅｘｉｔ与剪切应力τｗ和挤出胀大比Ｂ三者之间的关系。提出了描述这一关系的方程：ΔＰｅｘｉｔ＝τｗ（Ｂ＾４－１）＾０５／３。初步验证，用该方程计算的ΔＰｅｘｉｔ值与文献提供的毛细管挤出实测值有较好的一致性。     

纳米TiO2改性内墙涂料研究

主要研究了纳米TiO2的加入对内墙涂料性能的影响。结果表明,加入2%纳米TiO2能极大地提高涂料降解甲醛的能力,但加入4%纳米TiO2反而使涂料的性能变差。涂料的常规性能研究也表明,加入少于2%的纳米TiO2对涂料的常规性能会有极大的提高。     

Shear Stress in Smooth Rectangular Open-Channel Flows

The average bed and sidewall shear stresses in smooth rectangular open-channel flows are determined after solving the continuity and momentum equations. The analysis shows that the shear stresses are function of three components: (1) gravitational; (2) secondary flows; and (3) interfacial shear stress. An analytical solution in terms of series expansion is obtained for the case of constant eddy viscosity without secondary currents. In comparison with laboratory measurements, it slightly overestimates the average bed shear stress measurements but underestimates the average sidewall shear stress by 17% when the width–depth ratio becomes large. A second approximation is formulated after introducing two empirical correction factors. The second approximation agrees very well (R2>0.99 and average relative error less than 6%) with experimental measurements over a wide range of width–depth ratios.     

Interface Characteristics and Laboratory Constructability Tests of Novel Fiber-Reinforced Polymer/Concrete Piles

Conventional pile materials such as steel, concrete, and timber are prone to deterioration for many reasons. Fiber-reinforced polymer (FRP) concrete composites represent an alternative construction material for deep foundations that can eliminate many of the performance disadvantages of traditional piling materials. However, FRP composites present several difficulties related to constructability, and the lack of design tools for their implementation as a foundation element. This paper describes the results of an experimental study on frictional FRP/dense sand interface characteristics and the constructability of FRP–concrete composite piles. An innovative toe driving technique is developed to install the empty FRP shells in the soil and self-consolidating concrete is subsequently cast in them. The experimental program involves interface shear tests on small FRP samples and uplift load tests on large-scale model piles. Two different FRP pile materials with different roughness and a reference steel pile are examined. Static uplift load tests are conducted on different piles installed in soil samples subjected to different confining pressures in the pressure chamber. The results showed that the interface friction for FRP materials compared favorably with conventional steel material. It was shown that toe driving is suitable for installation of FRP piles in dense soils.     

水下长隧道最小安全顶板厚度研究

根据轴线地质剖面和隧道轴线布置图,对某拟建中水下公路隧道最小安全顶板厚度的确定进行了研究,通过比较得出最合理的最小安全顶板厚度,对同类工程有很大的参考价值。     

剪切场下聚合物结晶形态学研究进展

聚合物熔体被引入剪切场后，会发生与静态下不同的结晶现象。微观上可以得到伸直链晶体、片晶及串晶；宏观上除了静态下典型的球晶外，还能观察到球晶的变形和柱晶等。另外，剪切还可以使晶体发生晶型转变。本文对聚合物熔体在剪切场下结晶形态学的研究进展进行了介绍。     

岩溶地区施工人工挖孔桩及基岩爆破应注意的问题

徐州皇城大厦桩基工程--人工挖孔嵌岩桩在基岩爆破施工时,发生井下塌方,造成施工困难。对此,根据工程地质和现场施工情况,对爆破后的基岩进行护壁,从而消除了井下塌方事故,使工程得以顺利进展。     

框剪悬挂结构的动力特性分析

介绍了悬挂结构特点，利用奇异函数方法建立了悬挂框剪结构的侧移刚度矩阵和动力方程．采用Matlab算法语言编程计算了悬挂框剪结构的频率和阵型，对影响框剪结构动力特性的参数(主结构的侧移刚度，分层悬挂时的悬挂位置)进行了计算和讨论．