Kinetics of hydantoin formation

The reaction of lignite in a slagging gasifier produces reactants which in turn form 5,5-dimethylhydantoin (DMH) as a major constituent in the condensate water. Variations in plant operating conditions made it impossible to accurately study the kinetics of formation of DMH in the actual gasifier water, and thus a model system was chosen. The reaction of acetone cyanohydrin in the presence of excess ammonium carbonate at concentrations approaching those obtained in the condensate water were studied at 50,70, and 90 °C. Secondorder kinetics were obeyed, and the pseudo second-order rate constants at the respective temperatures were 1.86, 3.6, and 4.62 dm³ mol^{? 1} h^{? 1}. Independent variation of the concentration of either acetone, cyanide, ammonia or carbonate gave results consistent with the interpretation that the formation of DMH is first order in all reactants: rate of formation of DMH = k[acetone][HCN][NH₃][CO₂]. The pseudo second-order rate constant is a complex rate constant including several rapid equilibria. A mechanism consistent with the kinetic data is presented.     

Precision equipment for symmetrical bending— Part 1. The loading system

The design and performance of precision bending equipment for testing straight beams with constant rectangular section under a pure bending moment is described. Part 1 deals with the loading arrangements and Part 2 with the rig for measuring beam deflection. The methods for recording deflection of strain gauges applied on the beam have been described elsewhere.^1–4
The reactions to the deadweight gravity loads are taken via ball bearings. The total bending moment inaccuracy, i.e. the sum of estimated systematic errors and random errors, the latter expressed as the 2Ga confidence interval about the mean (2G_cim), is about ± 25 x. 10^-4%, for 23 tests with a steel beam with 15 mm × 75 mm cross sectional dimensions, loaded to 1-1.5 mm/m strain.
The measuring rig stands on the beam via hardened and polished spherical segment feet and uses a capacitive transducer system with less than 5nm resolution. Various application tasks are described. The total inaccuracy of the measured deflection, i.e. apart from bending moment inaccuracy, is about ± 35 times 10^4% for about 10 reproduced, not repeated, tests with the same steel beam. The deflection for such a beam is of the order of 2 to 4 mm.     

土壤源热泵取热的实验研究

通过广泛分析国内外对土壤源热泵实验研究的现状,建立了可以模拟多个地区、多种运行工况的土壤源热泵沙箱实验台,并进行了绝热边界工况短期内取热的实验研究。     

Amorphous diffusion bonding of steel pipe and its impact toughness

An iron-based amorphous foil (FeNiCrSiB) was used as an interlayer for the amorphous diffusion bonding of low carbon steel pipes under argon flux. The microstructure and mechanical properties of the joint were analyzed using an electron probe micro-analyzer (EPMA), tensile test, bending test and impact test. The results show that the joint microstructure resembles that of the base metal and no precipitates form at the joint. Melting point depressants (B, Si) diffuse far away from the joint and the base metal element is homogenous across the joint. The joint impact toughness is greater than the base metal toughness and the mechanical properties of the joint are similar around the pipe.     

合理开发利用钨矿资源 促进钨矿业可持续发展

简述了我国钨矿业概况、现有采选技术水平及钨矿加工利用率 ;从资源配置出发 ,阐述了钨矿业发展存在的几个主要问题 ,并且针对性地提出了可持续发展的几点建议。     

Model Validation for Bridge-Road-Vehicle Dynamic Interaction System

The dynamic response of highway bridges subjected to moving truckloads has been observed to be dependent on (1) dynamic characteristics of the bridge; (2) truck configuration, speed, and lane position on the bridge; and (3) road surface roughness profile of the bridge and its approach. Historically, truckloads were measured to determine the load spectra for girder bridges. However, truckload measurements are either made for a short period of time [for example, weigh-in-motion (WIM) data] or are statistically biased (for example, weigh stations) and cost prohibitive. The objective of this paper is to present results of a 3D computer-based model for the simulation of multiple trucks on girder bridges. The model is based on the grillage approach and is applied to four steel girder bridges tested under normal truck traffic. Actual truckload data collected using a discrete bridge WIM system are used in the model. The data include axle loads, truck gross weight, axle configuration, and statistical data on multiple presence (side by side or following). The results are presented as a function of the static and dynamic stresses in each girder and compared with code provisions for dynamic load factor. The study provides an alternate method for the development of live-load models for bridge design and evaluation.     

Experimental Investigation of FRP-Strengthened RC Beam-Column Joints

The results of a comprehensive experimental program, aimed at providing a fundamental understanding of the behavior of shear-critical exterior reinforced concrete (RC) joints strengthened with fiber reinforced polymers (FRP) under simulated seismic load, are presented in this study. The role of various parameters on the effectiveness of FRP is examined through 2/3-scale testing of 18 exterior RC joints. Conclusions are drawn on the basis of certain load versus imposed displacement response characteristics, comprising the strength (maximum lateral load), the stiffness, and the cumulative energy dissipation capacity. The results demonstrate the important role of mechanical anchorages in limiting premature debonding, and they provide important information on the role of various parameters, including: area fraction of FRP; distribution of FRP between the beam and the column; column axial load; internal joint (steel) reinforcement; initial damage; carbon versus glass fibers; sheets versus strips; and effect of transverse beams.     

Identification of photoluminescence features of an epoxy resin based on components features and curing effects

Photoluminescence features in a commercial grade cured DGEBA-based epoxy resin have been investigated with as objective to determine which of the material compounds are responsible for cured resin emissions. The origin of the bands has been approached by considering photoluminescence of base resin and hardener taken separately, of their mixture, and in the course of curing. Most of the bands observed in the cured resin could be interpreted based on those found in the components taken separately. Fluorescence of the cured resin appears dominated by two broad bands that are characteristic of the hardener and exhibits a blue shift by up to 30 nm in the course of curing which could be used for cure monitoring purpose of the investigated system. Fluorescence of the base resin is clearly detected in the resin cured with tertiary amine as catalyser. However, it is very weak if the catalyser is not added. Two phosphorescence processes have been isolated in the cured resin, one of them being related to the base resin. Finally, a chemiluminescence spectrum has been recorded in the course of curing, which has been related to either curing-related reactions or to an oxidation process.