灌注桩高应变测试若干问题探讨与实例分析

本文分析了灌注桩高应变检测中存在的各种问题,指出可能影响拟合分析结果精度的主要因素,并通过某检测实例的动静对比分析,证明高应变法应用于桩身完整性和单桩极限承载力推定是可行的,可作为大直径灌注桩静载试验的有效补充。     

公路桥梁施工中钢纤维混凝土技术的应用研究

本文通过对钢纤维混凝土性能的仔细分析,提出了钢纤维混凝土技术在公路桥梁施工中的应用,并对其施工技术要点做了研究探讨,以供读者阅读和参考。     

巨型五边形钢柱加工方案的研究

大连国贸中心大厦总高320 mm,其外框柱采用的是五边形的巨型钢结构,该形式的外观结构在国内较为罕见,且需兼顾前期施工的影响,在钢结构设计与加工方面具有一定的难度.以此为出发点,介绍了2种加工方法：地样法与胎架法,通过分析两者的优劣势最终确定了地样法的方法来加工钢结构.该方法为实际工程提供了切实可行的思路与依据,可为相关工程提供借鉴与参考.     

一种常见电梯鼓式制动器的性能改进及其检验

制动器是电梯重要的安全部件,一旦失效,可能造成轿厢蹴底、冲顶、开门运行以致人员受到剪切伤害等严重后果。所以,电梯的制动系统除了电气制动外,还应有一个机一电式摩擦型的制动器,其兼备了驻车制动和行车紧急制动的功能。     

透明硅烷改性聚醚密封胶的研制

以硅烷改性聚醚树脂(MS树脂)为基料,加入增塑剂、气相二氧化硅、偶联剂、自制催化剂等助剂,制备了一种透明硅烷改性聚醚密封胶(MS密封胶)。该密封胶固化后拉伸强度为2.93 MPa,断裂伸长率为258%,1 mm厚胶片的透光率达92%,综合性能较优,能够满足相关标准的要求。     

浅谈村镇规划中存在的问题

一、前言当前,国家把解决“三农”问题作为工作的重中之重,要求跳出农业抓农业。2003年6月,浙江省政府召开专题会议,启动“千村示范、万村整治”工程,提出以中心村建设为重点,推动城市基础设施向农村延伸,推动城市公共服务事业向农村覆盖,推动城市文明向农村辐射。实施“千村示范、万村整治”工程,加大村庄环境整治的力度,完善农村基础设施,加强农村基层组织和民主建设,加快农村社会发展,使农村面貌有一个明显改变。为加快实现农业和农村现代化,为保证农民物质文明、精神文明上一个新台阶打下扎实的基础。在这个政策的指引下,近几年全国各地…     

Tribological Characteristics of Aqueous Graphene Oxide,Graphitic Carbon Nitride,and Their Mixed Suspensions

The tribological performance of graphene oxide (GO), graphitic carbon nitride (g-C₃N₄), and their mixed (g-C₃N₄/GO) aqueous suspensions was investigated. The 0.06 wt% GO, 0.06 wt% g-C₃N₄, and 0.06 wt% 1:1 g-C₃N₄/GO suspensions reduced the coefficient of friction (COF) by 37, 26 and 37% and wear mark radius by 19.1, 16.0 and 19.6%, respectively, in comparison with water. Pure g-C₃N₄ and GO suspensions showed unstable lubrication in the tests with relatively high loads and speeds, while the g-C₃N₄/GO mixed suspension had superior tribological performance in all tested conditions. This is because in the mixed suspension g-C₃N₄ agglomerates became smaller, and GO nanosheets exhibited fewer wrinkles and less stacking, which enabled the formation of a layer of tribo-composite film. As a result, the friction, wear and tribo-corrosion were reduced during sliding.     

Rapid Bonding of Ti3SiC2 and Ti3AlC2 by Pulsed Electrical Current Heating

Inspired by pressure resistance welding of metallic materials, herein we describe how two MAX phases—Ti₃SiC₂ and Ti₃AlC₂—were successfully joined by a rapid electric current heating method in a pulsed electric current sintering furnace. No welding agent was employed and the total processing time was less than 6 min. When the bulk temperature of the joint couple exceeded 1070°C, good joints, with shear strength above 50 MPa, were achieved in both homo‐ and heterojunction joints.     

Tuning of dielectric and ferroelectric properties in single phase BiFeO3 ceramics with controlled Fe/Fe ratio

Single phase multiferroic BiFeO₃ (BFO) ceramics were synthesized with controllable amount of Fe²⁺ and oxygen vacancies in a very wide concentration range. Double ferroelectric hysteresis loops are observed in fresh BFO ceramics at room temperature without any aging processes. Detailed study shows that this is due to the defect dipoles which have preferential orientations antiparallel to the direction of spontaneous polarization, providing a driving force for domain back-switching. The dielectric constant of BFO could be enormously enhanced by 100 times by increasing the Fe²⁺ content, employing a polaronic relaxation process.     

A Moisture Transfer Model for Isothermal Drying of Plant Cellular Materials Based on the Pore Network Approach

Plant materials with cellular structure, like fruits and vegetables, are often viewed as porous media in terms of model building of the drying process, on the basis of a hypothesis that all of the moisture of a plant tissue is trapped in a continuous and connected pore network system. However, most of the moisture in the plant tissue is contained naturally in enclosed cells. In the course of drying, the trapped moisture has to cross the cell membranes and then migrates in the extracellular space. Based on this concept, a pore network model for isothermal drying of plant materials was developed in which two stages of moisture movement—transmembrane transfer and extracellular transfer in the pore network—were considered. Finally, the isothermal convective air-drying processes of a potato slice were simulated. The calculated results were validated by the experiments conducted under the simulation conditions.