基于希尔伯特变换的应力波波速估计的研究

研究基于希尔伯特变换的时间延迟估计方法及其算法,算法通过MATLAB语言编程实现。制作了4块混凝土板并在其上开展基于冲击反射法的双传感器波速测量实验,将互相关时延估计和希尔伯特变换时延估计应用到波速估计中,两者均能解决直接观察法中的人为误差的影响和噪声对测量精度的影响,取得比较满意的结果,希尔伯特变换时延估计得到的波速精度比互相关时延估计得到的波速估计精度更高。     

一座多跨预应力混凝土连续梁桥的施工过程分析

对安徽马鞍山至芜湖高速公路青山河大桥进行施工过程的数值模拟结构分析,计算出用于本桥施工的理论预抛高值,指导该桥的施工线形控制。中小跨径的多跨预应力混凝土连续梁桥的施工线形控制的关键是确定施工预抛高,文中对此提出了需要考虑的有关因素和计算方法。     

驾驶员安全可靠性多因素分析

影响驾驶员安全可靠性的身心因素很多,研究中对22项指标进行分析,将有关指标合并,归纳为6种主因子:第一主因子相关变量5种,反映驾驶员的反应能力;第二主因子相关变量4种,反映中枢神经系统的平衡控制能力;第三主因子相关变量5种,反映驾驶员视觉功能;第四主因子相关变量4种,反映注意综合品质;第五主因子相关变量3种,反映驾驶员速度判断能力;第六主因子为驾驶员听觉能力。基于主因子分析进一步整合,建立驾驶员安全可靠性评价指标体系。     

异形变截面多室曲线箱梁桥的试验研究及三维有限元分析

在对某异形变截面多室曲线箱梁桥试验研究的基础上,构造可以综合考虑拉压、弯扭、畸变、剪力滞及其耦合作用的三维虚拟层合单元法,并对该异形桥梁进行空间有限元分析。理论分析和试验研究表明,利用此法对这种复杂的异形桥梁结构进行空间分析,具有模型单元少、计算效率和精度高的特点,完全可以满足实际工程的需要,是一种简单方便的实用计算方法。最后,综合考虑在一期恒载和纵向预应力筋作用下其应力的空间分布情况。研究成果可供工程设计和施工参考。     

汽车碰撞试验台动力学模型建立与分析

汽车碰撞试验已经成为我国强制性法规试验检测项目,而汽车碰撞试验台的动力特性是进行试验台能力设计、弹射过程控制、速度控制等的基础。本文分析了基于橡皮绳储能介质的汽车碰撞弹射试验台,建立充分考虑橡皮绳质量、摩擦系数、车辆质量、旋转质量因素和空气阻力等影响因子的试验台动力学模型,并经试验得到很好的验证,并提出基于过程动力特性方程的控制算法,所得结论可为同类试验台架系统设计和提高过程控制提供理论参考。     

Bosch VDC系统的控制原理及展望

VDC系统(Vehicle Dynamics Control、车辆动力学控制系统，在美日等国称为VDC，而在欧洲称为ESP，Electronic Stability Program，即电子稳定程序)是Bosch公司1995年推出的用于改善车辆操纵稳定性的一种车辆动力学控制系统。VDC系统包括两个控制回路：控制车辆运动的主控制回路，控制制动和驱动滑移的副控制回路。文中详细介绍了这两个回路的工作原理，并给出了改善车辆操纵稳定性的实例。最后，指出了VDC系统的发展趋势。     

基于CC工法建造的地下结构受力分析

CC工法作为一种新型地下暗挖技术,为地下工程暗挖施工提供了新的思路,其核心思想是将机械化暗挖小断面结构转换为大断面地下空间建筑结构。为了研究CC工法的结构受力情况,满足CC工法的工法特点需要,使结构安全可靠经济适用,故设计和分析其单元结构和整体结构,并结合CC工法的具体工程应用案例,选取CC工法的3个主要工况进行结构受力分析和设计,得到不同工况的弯剪轴力结果。结果表明： 设计方法和思路较为全面,设计结果安全可靠,能够较好地满足工程需要;同时,研究也为CC工法结构分析和设计提供了方法和依据,为今后相关工程提供了一定的参考。     

基于无人水面艇感知网的目标船航迹关联与数据融合

针对现有无人水面艇（Unmanned Surface Vehicle,USV）在航行过程中感知周围航行目标时出现的数据源单一、数据延迟、数据丢失等问题,提出一种基于USV搭载的航海雷达和全球定位系统（GPS）数据源的USV海上航行目标感知数据融合方法。基于最小误差法提出雷达原始图像数据解析算法,并采用数据剔除、时间空间统一方法完成对目标数据预处理,构建基于欧氏距离和马氏距离的航迹关联算法模型、基于层次分析法（Analytic Hierarchy Process,AHP）和专家评价法的融合数据权重分配模型。同时,开展USV试验研究,验证整体融合方法。结果表明,目标原始数据预处理方法合理可靠,融合算法稳定可信,可为USV海上航行目标感知、安全航行及快速避碰提供技术和算法支持。     

A numerical study on the installation configuration design of compliant vertical access riser (CVAR) in deepwater

In oil and gas transportation, the compliant vertical access riser (CVAR) system conducts economic and operational advantages due to its special configuration. In this paper, the static performance of the CVAR is studied by an efficient numerical method. According to the unique configuration of the CVAR, the mathematical model is established based on minimum total potential energy principle. The equilibrium equations are discretized by finite difference method and then solved by Newton-Raphson technique. The accuracy of the numerical method is verified by OrcaFlex software. Detailed parametric analysis is carried out based on practical engineering requirements. The effects of buoyancy section's configuration including buoyancy factor, buoyancy section's length and buoyancy section's location, and external environmental factors including wellhead offset distance, water depth and current velocity on installation shape and mechanical properties of the CVAR are analyzed. The research shows that the presented numerical method has good applicability and flexibility for the early installation configuration design of marine risers which have no touchdown section but only one touchdown point and are equipped with multiple buoyancy blocks subjected to forces of different directions and magnitudes, such as CVARs.     

Experimental study on dynamic response of a floating offshore wind turbine under various freak wave profiles

This study performed experimental investigation on the dynamic response of an in-place floating offshore wind turbine (FOWT) under freak wave actions. Based on the method of wave profile modulation, various freak wave profiles embedded in unidirectional Gaussian seas were generated in wave basin and the action of these waves on the FOWT was measured and analyzed, which has not been done before. The motions of FOWT were analyzed in time domain as well as time-frequency domain. The effect of freak wave parameters on FOWT motions was addressed, i.e., freak wave height, freak wave period, large crest, and deep trough. The dynamic response of FOWT was observed as a spike at the occurrence of freak wave in a conventional random wave, where the impact of freak wave can last for 17 spectral peak periods of wave. Data analysis shows that the motions of FOWT increased linearly with the freak wave height. In addition, the occurrence of freak wave induced the coupled effect on surge and pith, which was strengthen with the increase of freak wave height and wave period. Compared to a large crest, a deep trough of freak wave led to stronger motions and was supposed to be a key concern on the safety of the FOWT. The novel findings in this study provided a reference for the design of survival load on a FOWT and benchmarks for validating numerical models.