海洋油气钻采中海洋平台环境载荷分析

随着油气需求量的不断增加,海洋油气勘探开发的力度逐步增大,对海洋平台的使用越来越多。海洋平台作为服役于恶劣境且承受风、波浪、海流和地震等多种载荷作用的结构体,其安全性对油气开采有重要影响。通过分析风载荷、波浪载荷、海流载荷和地震载荷对平台的作用形式,得到平台在不同服役环境下这些载荷作用于平台的动态响应,对海洋平台的结构设计、强度分析及其安全评估具有重要意义。     

极端风速条件下风力机结构动力响应特性研究

为评估极端风速条件对风力机动力响应的影响，掌握风力机运行中的不利风速条件，以某2MW陆上风力机为例，基于FAST软件分别进行极端运行阵风、极端方向变化、垂直极端风切变和水平极端风切变四种条件下的风力机动力响应计算，并将结果与稳态风作用下的结构响应对比，分析不同极端风速条件对风力机动力响应的影响。算例结果表明，垂直极端风切变对叶根挥舞弯矩变化幅值最大；俯仰弯矩是塔底的控制载荷，在持续极端风速条件的范围内，极端运行阵风是塔底俯仰弯矩的最不利风速条件；当出现极端风向变化且未进行风力机偏航操作时，载荷与振动幅值将高于原有水平，加剧风力机结构发生疲劳破坏的风险。     

基于振动检测的海洋平台固有特性评估方法

海洋平台作为海上油气开采的主要结构形式,在整个生命周期中都会受到外部复杂环境载荷的作用,海洋平台结构长时间在这些载荷的作用下,有时会出现安全问题.一旦海洋平台结构发生破坏,造成的损失是不可估量的,因此,为了做到防患于未然,对于在役中后期的海洋平台进行结构安全评估显得非常必要,文中所述的振动检测评估海洋平台的固有特性就是一种非常有效的手段.     

多载荷工况下塔式起重机的强度、刚度和安全裕度

基于有限元参数化建模技术,运用Ansys中的APDL程序语言编写了塔式起重机整机金属结构命令流,在自重、起升载荷、风载荷等共同作用下选择3种危险工况,进行结构强度、刚度有限元分析,得到塔式起重机结构最大应力发生的位置和变形最大出现的位置。对整机结构稳定性进行了研究,得到不同工况下的临界极限载荷,来确定塔式起重机不同工况下的安全裕度。     

基于Ansys的船用甲板起重机结构风振响应研究

以工程中风载荷研究所通用的Davenport谱为基础,以有限元分析软件Ansys为操作平台,对船用甲板起重机金属结构风载荷作用下的动态响应进行仿真研究,并对整机结构的风振系数做数值计算,为工程中风载荷效应的研究提供理论参考.     

波浪作用下ETMD对W12—1海洋平台振动控制分析

建立W12-1海洋平台的有限元模型.利用MATLAB编写程序,生成不同有效波高时随机波浪载荷.在不同波浪载荷的作用下,选择合适的ETMD系统参数,获取有ETMD减振系统和无ETMD减振系统情况下海洋平台有限元模型节点的位移时程曲线.对海洋平台振动控制效果进行有限元分析表明:ETMD减振系统能够有效控制海洋平台在随机波浪载荷作用下的振动,平台甲板位移最小减少64.46%,最大减少87.86%;平台整体在不同波浪载荷作用下的平均减振效果分别为67.06%、86.90%和80.01%.     

船用甲板起重机臂架结构风振响应研究

以工程中风载荷研究所通用的Davenport理论为理论基础,利用有限元分析软件ANSYS和动力学分析软件MSC．ADAMS为操作平台,对风载荷作用下的船用甲板起重机臂架结构的响应进行仿真分析,并对其风振系数进行数值计算,为工程中风载荷效应的研究提供理论参考。     

大型门式起重机的风振特性研究

为了解随机风载荷在风灾频发地区对大型门式起重机的影响,借鉴建筑工程学中随机风载荷的处理方法,利用风载荷功率谱密度函数得到风载荷的时程曲线并应用于门式起重机的风振特性研究,利用计算流体软件对风场进行模拟仿真,在起重机行业还不够成熟。工程界对于结构的动态响应分析一般有时域和频域两种分析方法,虽然频域分析法方便迅速,但时域分析因其在复杂系统的非线性方面的优势以及其计算结果的精确直观并易于掌握结构的整机风振特性,更易被结构工程师所接受。利用ANSYS软件分析了门式起重机金属结构在静风载荷和随机风载荷作用下的响应,通过对比得出,大型门式起重机在不考虑风载荷的脉动效应时将使计算结果偏于不安全。     

仿生波浪滑翔器的可靠性验证

由于海洋气象条件复杂,极端海况时有出现,因此需要对仿生波浪滑翔器在极端海况下的可靠性进行验证。利用ANSYS流固耦合技术,分别对水下牵引机和水面浮体平台进行分析,验证仿生波浪滑翔器具有高可靠性,可抵御浪高为14 m的海浪。     

海洋平台起重机臂架在波浪载荷作用下的瞬态动力学分析

海洋平台起重机在正常服役期间通常会受到除工作载荷之外的环境载荷的严重影响,而以往对海洋平台起重机的研究都着重于考虑工作载荷的作用,对此,文中对环境载荷中破坏力较大的随机波浪载荷进行模拟计算。首先基于JONSWAP谱采用WAWS法对波浪载荷进行模拟,在验证方法的正确性后计算了海洋平台在随机波浪载荷作用下的运动响应;然后将海洋平台加速度谱作为输入计算了起重机臂架的瞬态动力学响应,得到了随机波浪载荷作用时起重机臂架的薄弱部位,从而可以在设计或者生产制造时对相应的部位进行加强。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.