桥梁颤振气动导数识别的迭代法

本文提出一种利用自由振动响应通过年顿－拉夫逊迭代同时识别出桥梁全部8个颤振气动导的方法。此法具有对迭代初值要求不高，识别结果稳定的特点，并具有一定的抗噪声干扰能力。数字仿真与实物试验结果表明本文方法有效，可行。     

Approximate channel identification via δ‐signed correlation

A method of approximate channel identification is proposed that is based on a simplification of the correlation estimator. Despite the numerical simplification (no multiplications or additions are required, only comparisons and an accumulator), the performance of the proposed estimator is not significantly worse than that of the standard correlation estimator. A free (user selectable) parameter moves ‘smoothly’ from a situation with small sum‐squared channel estimation error but hard‐to‐identify channel peaks, to one with a larger sum‐squared estimation error but easy‐to‐identify channel peaks. The proposed estimator is shown to be biased and its behaviour is analysed in a number of situations. Applications of the proposed estimator to sparsity detection, symbol timing recovery and to the initialization of blind equalizers are suggested. Copyright © 2002 John Wiley & Sons, Ltd.     

构造性神经网络在测井岩性识别中的应用

测井岩性识别是石油勘探中十分重要的基础工作,准确的岩性识别结果可以为勘探和开发提供可靠的依据。人工神经网络方法可对复杂的高维数据进行非线性映射,在模式识别领域得到越来越广泛的应用。针对传统的BP神经网络算法存在收敛速度慢、隐层数以及隐层节点数难以确定等缺点,研究了一种构造性神经网络学习算法---级联算法（Cascade Correlation Algorithm,简称CC算法）及其在石油工程中的应用。采用该算法对甘肃镇原-泾川地区进行岩性识别研究,通过与BP神经网络的识别结果进行比较,体现出构造性神经网络的优越性。     

Accumulation of amplified target DNAs using thiol/biotin labeling, S1 nuclease, and ferrocene-streptavidin-magnetic system and a direct detection of specific DNA signals with screen printed gold electrode

Combinations of PCR-based amplification platform using 5′ thiolated and biotinylated specific primers, S1 nuclease-PCR products treatment, ferrocene-streptavidin (Fc-Stv)-magnetic binding for DNA accumulation, and screen printed gold electrode for the DNA allocation, were applied to Hoechst 33258-induced DNA aggregation and signals induction system for direct signals detection and DNA quantification in food samples. Thiolated and biotinylated at each 5′ terminus enabled DNA purification through S1 nuclease treatment for primers and non-specific DNA elimination and enabled DNA trapping with a ferrocene-streptavidin-magnetic system. This facilitated the accumulation of target DNAs at higher concentration, resulting in enhanced signals. After allocation of DNA on the surface of gold electrode via thiol binding, intensity of DNA signals through these treatments could be measured directly after being induced by Hoechst 33258. Wider amplitude changes in anodic current peaks between negative and positive samples (increasing from 3.70 to 10.10 μA) compared with those applied with no treatment combinations (decreasing from 3.92 to 1.23 μA) were observed. This enhancement of the signals allowed a greater efficiency of DNA quantification. When this combination was used for GMOs content estimation in reference samples, results revealed an improved accuracy from 66% to 96%. The combined biosensor system, although more costly than the standard Hoechst 33258/carbon electrode system, provided an alternative choice for DNA quantification, offering labor-free immobilization of probe onto electrode surface, easy test administration, and efficient semi-quantitative test without expensive instruments.     

曙光油田超稠油井套管损坏的机理和防治

超稠油特殊的油藏特点决定了其生产周期短、注汽频繁、出砂、汽窜、超覆现象严重，以及套管质量等因素的影响，套管损坏较为严重。对曙光油田超稠油井套管损坏的规律和机理进行了研究，并从钻井和完井工艺的完善、套管钢级和射孔工艺的选择、采油生产参数的确定、注汽管柱隔热效果的提高、防治砂工艺等方面，对套管损坏提出了预防措施和对策。并对套管损坏井制定了修复再利用方案。     

Modelling of fatigue damage progression and life of CFRP laminates

A progressive fatigue damage model has been developed for predicting damage accumulation and life of carbon fibre‐reinforced plastics (CFRP) laminates with arbitrary geometry and stacking sequence subjected to constant amplitude cyclic loading. The model comprises the components of stress analysis, fatigue failure analysis and fatigue material property degradation. Stress analysis of the composite laminate was performed by creating a three‐dimensional finite element model in the ANSYS FE code. Fatigue failure analysis was performed by using a set of Hashin‐type failure criteria and the Ye‐delamination criterion. Two types of material property degradations on the basis of element stiffness and strength were applied: a sudden degradation because of sudden failure detected by the fatigue failure criteria and a gradual degradation because of the nature of cyclic loading, which is driven by the increased number of cycles. The gradual degradation of the composite material was modelled by using functions relating the residual stiffness and residual strength of the laminate to the number of cycles. All model components have been programmed in the ANSYS FE code in order to create a user‐friendly macro‐routine. The model has been applied in two different quasi‐isotropic CFRP laminates subjected to tension–compression (T–C) fatigue and the predictions of fatigue life and damage accumulation as a function of the number of cycles were compared with experimental data available in the literature. A very good agreement was obtained.     

Two-stage fatigue loading of woven carbon fibre reinforced laminates

A brief review of the models used to predict the cumulative fatigue damage in FRP composites is presented. Two‐stage fatigue loading of a [0/90,± 45₂,0/90]_s quasi‐ isotropic woven carbon fibre/epoxy resin laminate was evaluated at stress ratio R = 0.05 and the failure mechanisms investigated using x‐radiography after each loading stage. The results are presented in terms of fatigue strength and damage growth and are compared with those in the literature. A low‐to‐high loading sequence is more damaging than a high‐to‐low one and the Palmgren‐Miner linear damage rule may no longer be valid for this kind of material, as previously reported.     

疲劳/蠕变复合作用下聚苯乙烯的交互损伤研究

探讨了在疲劳／蠕变复合作用下聚苯乙烯的损伤交互作用，结果表明，在疲劳／蠕变复合作用下聚苯乙烯存在疲劳和蠕变的交互损伤，其断裂寿命比纯疲劳或纯蠕变的断裂寿命低；断裂机制是疲劳循环载荷松动和活化了分子链或链段，从而促进蠕变运动和断裂，并且，疲劳／蠕变的交互损伤程度与温度密切相关。     

电子认证与授权管理标准体系研究

以国际上在标识、鉴别与授权标准方面已有的工作为基础，提出了我国电子认证与授权管理标准体系框架。     

隧道受震破壞調查分析與修復管理案例

就隧道震後之災損模式進行統計與災損原因研判,並利用數值分析方法研判安全性,就結構加固等改善措施之設計考量作詳細說明;另由於隧道結構物的損壞範圍大,且修復經費受限,必須藉由定期檢测進行長期維護管理,以防範意外發生。於此,利用Vidco-GIS自動化影像地理资訊系統之e化新技術,以動態及靜態影像紀錄隧道災損狀況,同時亦整合建置前期設計、施工圖及定期維護等資料,相關成果以資料庫方式纳入日常維護管理,以有限人力有效率地進行維護管理紀錄並随時掌握現況供作決策之明確參考。