Analytical modeling and experimental study of tensile strength of asphalt concrete composite at low temperatures

In this study, analytical modeling of the tensile strength of hot-mix asphalt (HMA) mixtures at low temperatures was developed. To do this, HMA mixtures were treated as a two-phase composite material with aggregates (coarse and fine) dispersed in an asphalt mastic matrix. A two-phase composite model, which was similar to Papanicolaou and Bakos's [J. Reinforced Plast. Compos. 11 (1992) 104] model with a particle embedded in an infinite matrix, was proposed. Unlike Papanicolaou and Bakos's model, an axial stress was introduced to the fiber end to consider the load transferred from the asphalt mastic the aggregate. Efforts were also made to consider the effect of aggregate gradation, asphalt mastic degradation, and interfacial damage between the aggregates and asphalt mastic matrix on the tensile strength of the HMA mixtures. Experimental investigations were conducted to validate the developed theoretical relations. A reasonable agreement was found between the predicted tensile strength and the experimental results at low temperatures. Parameters affecting the tensile strength of asphalt mixtures were discussed based on the calculated results.     

经济型洗煤厂集中控制系统的设计

介绍以三菱FX系列PLC和工控机组成的洗煤厂分布式集中控制系统,同时给出了设计要求、硬件配置以及软件设计等。     

亚齐示范屋与生态技术

亚齐示范屋是在传承印度尼西亚当地住宅传统的基础上，海啸灾区重建的示范性建筑。从当地传统的传承、设计理念及生态技术方面对该示范屋进行了分析、研究，结合我国的情况得出我国生态建筑的发展策略。     

Modeling and performance analysis of IP access interface in optical transmission networks with packet switching

The article analyzes the influence of the Internet Protocol (IP) access interface on the packet loss probability and delay times in the optical packet switched network. The network and node model have been proposed, and the structure of the IP access interface, including assembler and holder, have been included in the analysis. It has been shown that the increase of the maximum optical packet sizes, as well as use of the holding feature as contention resolution mechanism, decrease the packet loss probability, but introduce delays at the optical network access points. Modeling and analysis were based on the discrete event simulation assuming self-similar traffic sources. IP packet lengths were modeled using empirical data. This work has been conducted while the author was affiliated with the Telecommunication Laboratory, Swiss Federal Institute of Technology (EPFL-STI-ITOP-TCOM), Lausanne, Switzerland     

数字式定温热偶真空计

本文介绍了一种新的数字式定温热偶真空计，它具有精度高、工作可靠、结构简单、操作方便等优点。文中具体阐述了微机系统的工作原理，并提供了结构原理框图。概述了研制中的关键技术问题，即用微机软件对非线性进行补偿的方法。最后介绍了该真空计的主要算法及应用实例。     

广播电视发射台技术指标集中自动测试系统

本文介绍了利用计算机技术、网络技术、三遥技术对广播电视发射技术指标进行实时自动测试的系统，以便进一步为安全优质播出提供技术保证。     

公路涵洞CAD系统

介绍作者开发的公路涵洞ＣＡＤ系统的设计原理和实现方法．该系统已在工程设计中体现出其先进的系统设计和优越的系统性能．     

Valid parameter range analyses for chemical reaction kinetic models

The present work quantifies the relations between the structure of a chemical reaction kinetic model, its valid parameter range, and the truncation error tolerance of the model. General methods are presented to solve the three important problems of valid parameter range analysis: (1) identification of the valid parameter range of a kinetic model, (2) estimation of the error tolerance required when applying a kinetic model over a specified parameter range, and (3) improvement of existing model generation algorithms to construct more robust models. Finally, the relationship between a model's structure, its valid parameter range, and the truncation error tolerance are illustrated by the flexibility-tolerance-model graph. The new methods are applied to pyrolysis of methane/ethane mixtures.     

套管动力钳转矩监测系统

下套管作业时，套管螺纹联接质量的好坏直接影响着油井寿命，因此有必要研制一种套管动力钳转矩监测系统。以目前国内常用的ＴＱ－２０型套管动力钳为例，介绍了一种与之相配套的套管钳转矩监测系统的功能特点，测试原理，结构设计，并对实测各类紧扣曲线进行了分析。该系统采用主从机结构，主机为工业控制微机，从机为单片机系统，主从机采用远距离通信传输，大大地改善了工业控制微机的工况条件。该系统实现无人监控、自动记录、绘