Relationship between phenolic adhesive chemistry and adhesive joint performance: Effect of filler type on fraction energy

The performance of adhesive bonded joints depends on many factors, one of which is the adhesive formulation. The effects of organic and inorganic fillers upon the fracture toughness of phenol–resorchinol–formaldehyde adhesive in hard maple joints were explored in this study. Analytical techniques (DSC, IR, SEM, and GPC), and solubility studies were employed to relate physical effects to chemical effects of teh fillers. The resin showed two distinct stages of cure: (1) a low temperature exotherm associated with resorcinol and paraformaldehyde and (2) a high temperature endotherm associated with the base resin. Filler was found not to affect the cure. Fillers did have a profound effect on the morphology of the wood-adhesive interphase and upon the bulk adhesive properties. These effects, revealed in both SEM and fracture toughness studies, are discussed at lenghth.     

Investigation of mechanical properties of fractured marbles by uniaxial compression tests

Uniaxial compression tests(UCTs)on 34 naturally fractured marble samples taken from the transportation tunnels of Jinping II hydropower station were carried out using the MTS815 Flex test GT rock testing system.Rockburst proneness index WET is determined for the marble samples with the UCTs.According to the number,size and spatial structure characteristics of the internal natural fractures of the marble samples,fractures are basically divided into 4 types,namely,single fracture,parallel fracture,intersectant fracture and mixed fracture.The mechanical properties of naturally fractured rocks(4 types)are analyzed and compared with those of intact rock samples(without natural fractures).Experimental results indicate that failure characteristics of fractured rocks are appreciably controlled by fracture distribution or fracture patterns.In comparison with intact rocks,the failure of fractured marbles is a locally progressive failure process and finally rocks fail abruptly.Statistically,the uniaxial compressive strengths(UCSs)of rocks with single,parallel,intersectant and mixed fractures are 0.72,0.69,0.59 and 0.46 times those of the intact rocks,respectively.However,the elastic modulus of the fractured Yantang marbles is generally not different from that of intact rocks.But the elastic moduli of Baishan marble with single,intersectant and mixed fractures are 0.61,0.62 and 0.45 times those of intact rocks,respectively.Experimental results also indicate that WET of fractured marbles is generally smaller than that of intact marbles,which implies that rockburst intensity of fractured marble in field may be controlled to some extent.In addition,the bearing capacity of surrounding rocks is also reduced,thus the surrounding rocks should be supported or reinforced timely according to practical conditions.     

Bonding Wood Veneers with Cellulose Solvents

Various solvent systems capable of dissolving cellulose have been reported in the literature. Cuene (cupriethylene diamine hydroxide) and FeTNa (ferric sodium tartrate) are well known examples. Preliminary experiments were conducted with Cuene and FeTNa to determine if the cellulose dissolving ability of these systems could be used to bond yellow birch veneers. The results indicate that relatively high dry shear strengths, and low wet shear strengths are obtained.     

TURBULENT FLOWS AROUND SAND DUNES IN ALLUVIAL RIVERS

The sand dunes are typical bed forms of natural alluvial rivers.In this article,a vertical 2-D Reynolds stress model is established for the simulation of turbulent flows around sand dunes,and water-sand boundary conditions are set with particular attention.By numerical simulations,the following conclusions can be drawn.(1) The flow resistance in rivers with sand dunes could be divided into the sand-grain resistance and the sand dune resistance,and the sand-grain resistance coefficient mainly depends on Reyn...     

长江三峡水利枢纽建筑物安全监测决策支持系统总体设计

结合三峡工程的特点,利用现代的信息技术对三峡工程水利枢纽建筑物安全监测决策支持系统进行总体设计。该系统主要包括三个面向用户的功能分系统,信息管理分系统、分析评价分系统和辅助决策分系统以及底层的系统支持库群,整个系统由计算机网络联成一个有机的整体。     

EXPERIMENTAL STUDIES ON FREQUENCY CHARACTERISTICS OF THE FLUCTUATING PRESSURE ACTING ON THE APRON OF STILLING BASINS WITH LOW FROUDE NUMBER

Using four types of stilling basin models,this paper studies frequency characteris-tics of the fluctuating pressure acting on the stilling basin apron when Froude number is notgreater than 4.5.The testing results show that the frequency of fluctuating pressure,f_s in theranges of 0. 4Hz≤f_s≤1.1Hz.0.2Hz≤f_s≤2.5Hz and 0.4Hz≤f_s≤3.3Hz.can be used as thedesign frequency corresponding to three patterns of hydraulic jump.The reliability of f_s for threejump patterns is all nearly equal to 90%.     

小浪底工程安全监测数据采集系统设计综述

小浪底工程规模大,地下洞室多,地质条件复杂,原型观测对枢纽安全运行具有十分重要的意义。本文系统介绍了工程安全监测数据采集系统的结构及配置、测站布置、功能要求、系统操作、系统软件、实施情况等。     

基于云计算的WebGIS系统构建探析

云计算作为一种技术趋势正迅速兴起,云架构和云服务所提供的技术和体系结构是当今地理信息系统研究和发展的关键领域。本文利用云计算和WebGIS均是基于网络化应用的相同之处,提出了基于云计算构建WebGIS系统的观点,阐述了基于云计算的WebGIS系统层级结构和应用体系结构设计方法,实现对海量空间数据存储、进行各种空间信息检索和空间分析的有力支撑。     

Set up the Mechanical Curriculum System Based on Three-Dimensional Design

1 Reform of Mechanical Curriculum System is the Needs of the Times 1.1 The Great Changes of Designing Methods and Manufacturing Techniques With the development of science and technology, our society has come to the era of knowledge economy and informatization. Informatization represents not only advanced manufacturing and management, but also enterprises?competition capacity. Moreover, it is important to join in international competition and cooperation. For example, the breakthrough in…     

Risk analysis model for landslide mass of high slope in dam area

In order to identify the threat of reservoir bank landslide to dam safety and reduce the risk of dam failure,impact factors of the landslide are analyzed.The concept of landslide risk degree is put forward to measure the threat of landslide to dam safety.The monotony of the landslide risk assessment function which changes with different affecting factors is analyzed qualitatively.Based on gene automatic programming,a data mining model of the landslide risk assessment function is constructed combined with im...