网络安全概述

介绍了计算机网络安全问题所涉及的各方面内容。从全局角度介绍计算机网络安全的概念、体系结构和模型，讨论了网络安全主要包含的内容和研究方向，介绍当前网络安全的主要产品。     

大线能量焊接耐火耐候建筑用钢的性能试验及应用研究

对武钢研制的大线能量焊接耐火耐候建筑用钢的力学性能、焊接性能与其典型应用进行了研究。试验结果表明：该钢具有优良的综合力学性能，在600℃温度下的屈服强度均高于其室温下屈服强度的2／3，完全满足建筑结构用钢耐火安全性的强度许用指标；该钢具有低的焊接冷裂纹敏感性，能承受大线能量(50～100kJ／cm)焊接；该钢在大型建筑应用中的实际效果良好。     

多自由度系统非线性参数识别的灵敏度方法

为了识别多自由度系统的非线性参数（3次阻尼系数、3次刚度系数和干摩擦力），提出一种基于灵敏度分析用测量响应（位移、速度或加速度）识别非线性参数的方法。将结构抽象为由线性和非线性阻尼、刚度连接的集中质量系统，用四阶Runge—Kutta法求解多自由度非线性系统的振动响应和振动响应对非线性参数的灵敏度。假定非线性参数为零初值，根据计算响应与测试响应的差值，由基于正则化的阻尼最小二乘法迭代识别系统的非线性参数值。算例表明，该方法可以有效地识别多自由度系统的非线性参数。     

Experimental study on the controlled air oxidation of sawdust in a packed-bed reactor

The controlled air oxidation technology is a promising way of disposing medical waste, which has been a huge challenge in China. It converts waste through partial oxidation into a gaseous mixture, small quantities of char and condensable compounds. But operational performance of the primary chamber of the controlled air incinerator is poorly understood, leading to difficulty in control. In this paper, a packed-bed reactor was established to study the effect of O₂ concentration on sawdust oxidation. The feed gas flow rate was kept constant at 0.6 m³/h at room temperature (26 °C) with O₂ concentrations varied from 6% to 12%. Temperature profiles of the beds, product yields and gas compositions in the out-of-bed fuel gas were measured in detail. The results showed that the sawdust beds achieved low temperatures for the given O₂ concentrations and leveled off in the oxidation processes. The bed temperatures increased and the solid yields decreased with the increase of O₂ concentrations. When the O₂ concentration was 10%, the gas yield reached a minimum and the liquid reached a maximum correspondingly. When the O₂ concentration increased from 6% to 10%, the peak concentrations of CO and CH₄ in the gas yield increased. However, when the O₂ concentration exceeded 10%, CO and CH₄ concentrations decreased. As O₂ concentration varied from 6% to 12%, CO₂ concentration increased continuously. This study provides a fundamental insight that the reaction processes could be well regulated by means of adjusting the feed air in practical units.     

Design of the HL-2M power supply control system

The power supply control system is one of the most important local control systems of HL-2M tokamak. The power supply system of HL-2M is composed of four flywheel generator sets with total capacity of 600 MVA, all the magnetic field coil power supplies and high voltage power supplies of auxiliary heating system. The control system of power supply should make sure the large amount of on-site equipment and facilities to operate steadily and reliably.This paper presents the architecture of HL-2M control system and four kinds of established control networks. It describes how the power supply control system is built by using the established hardware structures and software agreements. Specially, it is focused on introducing an application of real-time technology based on the reflective shared memory and the fully digital compact solution for controlling the high power converters. Otherwise, a scheme which adopts PROFINET and Sequence of Events technology to carry out the intellect interlock control system is given.     

预处理温度对SAPO-11催化丁烯骨架异构化性能的影响

采用水热合成法合成的SAPO-11分子筛，经酸洗、干燥和焙烧处理得H-SAPO-11分子筛，考察了预处理温度对催化剂物化性能的影响，采用XRD、XRF、IR和NH₃-TPD等手段对催化剂进行表征。实验证明，500 ℃预处理后H-SAPO-11分子筛的结构缺陷较少，B酸位较多，骨架更完美；将其成型制成催化剂，对丁烯骨架异构化反应显示更优良的催化活性、选择性和稳定性。     

Stimulated emission via quantum interference: Scattering of one-photon packets on an atom in a ground state

Abstract

Usually it is assumed that the stimulated emission appears as a consequence of the Bose—Einstein statistics of photons and that to observe this effect at least two excitations have to be initially present in the atom—field system. That is, both the atom and the electromagnetic field have to be excited. In this paper we show that stimulated emission can appear exclusively as a consequence of quantum interference in a system with just a single excitation. Specifically, we consider a single two-level atom which is initially in its lower energy state and it interacts with a single-photon multi-mode wave packet. We show that for a proper choice of the photon-wave packet the atom can exhibit stimulated emission.     

Effect of the water content of padded cotton fabrics on reactive dye fixation in the pad-steam process

A series of padded cotton fabrics with various water contents were obtained through vacuum dehydration. The effects of the water content on the fabric temperature variation during steaming, the colour properties, and the dye fixation rate (%F) were investigated. Dye distribution in the dyed cotton fibres was assessed. The influences of steaming time and sodium carbonate concentration on K/S value and %F of the dyed fabrics with low water content were also evaluated. The results indicate that reducing the water content of the padded cotton fabric to around 25.0% prior to steaming was favoured for reactive dyeing. The temperature of the wet fabric rose rapidly, the K/S value and %F were enhanced, and in addition the dye penetration into the dyed cotton fibres was sufficient. However, for padded fabrics with extraordinarily low and high water contents (e.g. 1.4% and 70.9% respectively), both the K/S value and %F were decreased. Furthermore, a white core phenomenon was evident for the fibres of the dyed fabric with a water content of 1.4%. Variation in the L^* values was in line with the K/S values as the fabric water content varied. As expected, steaming time and sodium carbonate dosage can also affect reactive dye fixation greatly and should be determined accordingly for dyeing cotton fabric with low water content.     

加氢装置原料泵的故障分析及处理

多级离心泵轴向力的设计及平衡对泵的正常使用有着重要的影响。本文以某石化公司加氢装置原料泵为例,介绍了鼓盘鼓平衡机构在多级泵中的应用特点,并对加氢装置原料泵出现的故障问题进行分析和解决。