螺旋桨诱导的船体表面力预报新方法

在已知船舶的质量、刚度、阻尼以及实测尾端振动速度的条件下,反推出螺旋桨叶频激振力.这是属于结构动力学的反问题即载荷识别问题.在深入研究国内外螺旋桨激振力计算方法以及综合分析影响螺旋桨激振力的各种要素后,采用载荷识别方法,提出计算空泡螺旋桨诱导的船体表面力的新公式,用该公式预报了四条船的表面力并与国外有关方法进行比较,预报的螺旋桨激振力与脉动压力值均在国外各公式预报值之间.用该公式预报的5.2万吨多用途货船的脉动压力值与空泡水筒中的实验值相比误差为21.8%;预报了30万吨超大型油船的激振力并由该激振力算出的尾端振动速度值与实测值相比误差仅为3.64%.     

船舶结构动载试验的基于参考测点随机子空间法

文章提出了基于参考点的随机子空间船舶模态参数识别方法.该方法直接根据环境激励下测得的输出响应来构建Hankel矩阵,并通过QR分解技术对数据进行精简,再对投影矩阵进行奇异值分解(SVD)来剔除噪声,最后识别出结构的模态参数.它不受FFT(傅立叶变换)的影响,识别速度快,精度高.对于需快速识别船舶结构的模态参数,检测其可能存在的损伤,建立起预警及适时维修机制提供了有效手段.     

Operational profiles of ships in Norwegian waters: An activity-based approach to assess the benefits of hybrid and electric propulsion

Various regulations are imposed on shipping to increase energy efficiency and reduce environmental impacts. Alternative fuels and power systems are among the solutions for compliance with these regulations. The power system of a ship may not operate optimally because of the diversity of the operational profile during its lifetime. This article uses an activity-based approach and big data from the Automatic Identification System (AIS) to study the operational profiles of eight ship types operating in Norwegian waters around mainland Norway in 2016. The aim is to identify ship types that can benefit from electric and hybrid propulsion through analysis of their operational profiles. Close to shore, the operational profiles of various ship types are similar, and all ships spend a great proportion of their time with lower loads. As the distance from shore increases, the operational profiles of various ship types follow distinct trends. Among the considered ship types, reefers spend more operational time close to the diesel engine design condition. On the other hand, offshore and passenger ships show the most dynamic operational profiles and spend a large percentage of their operational time with a partial load, away from diesel engine design conditions. Such ships can benefit from hybridisation, diesel-electric propulsion, and other electric concepts, such as batteries and fuel cells. Another option is to downsize diesel engines for better operation while fuel cells and batteries supply peak and partial loads. Operational profiles are plotted and details of the approach are presented in the article.     

Surrounding traffic complexity analysis for efficient and stable conflict resolution

The constant increase in air traffic demand increases a probability of the separation minima infringements in certain areas as a consequence of increased traffic density. The Annual Safety Report 2016 reports that in recent years the number of infringements, measured per million flight hours, had been increased at a lower rate (Eurocontrol, 2018). However, this level of infringements still generates a continuous pressure on the air traffic control (ATC) system and seeks for more control resources ready to tactically solve potential conflicts, while increasing at the same time the operational costs. Considering present air traffic management (ATM) trade-off criteria: increased airspace capacity and traffic efficiency but reducing the cost while preserving safety, new services must be designed to distribute the separation management ATC task loads among other actors. Based on the Single European Sky Air Traffic Management Research and Next Generation Air Transportation System initiatives, this paper proposes an innovative separation management service to shift the completely centralized tactical ATC interventions to more efficient decentralized tactical operations relying on an advanced surrounding traffic analysis tool, to preserve the safety indicators while considering the operational efficiency. A developed methodology for the proposed service is an application-oriented, trying to respond to characteristics and requirements of the current operational environment. The paper further analysis the traffic complexity taking into consideration the so-called domino effect, i.e. a number of the surrounding aircraft causally involved in the separation management service by the means of identification of the spatiotemporal interdependencies between them and the conflicting aircraft. This complexity is driven by the interdependencies structure and expressed as a time-criticality in quantifying the total number of the system solutions, that varies over time as the aircraft are approaching to each other. The results from two randomly selected ecosystem scenarios, extracted from a simulated traffic, illustrate different avoidance capacities for a given look-ahead time and the system solutions counts, that in discrete moments reach zero value.     

无人水下航行器外热源热机用无气体产生燃料

无人水下航行器(UUV)在军事领域正得到愈发广泛的应用,动力装置是其技术难点之一。无人水下航行器采用外热源热机,在续航力和航速上,都优于其他类型动力装置,且使用无气体产生燃料,可从根本上解决水下气体排放问题,提高航行隐蔽性,具有良好的军事应用前景。本文根据无人水下航行器的使用条件和技术要求,对适用于无人水下航行器外热源热机的无气体产生燃料进行了广泛考察,给出了可用于无人水下航行器外热源热机的无气体产生燃料和氧化剂的组合。     

基于铜排的新型短路保护用大电流传感器的分析与设计

由于含有铁芯,现有保护装置上铜排用大电流传感器传感器笨重,繁杂并且占用较大体积。这对珍贵的船用空间十分不利。考虑到大电流时铜排周边能对传感器形成大干扰的可能性较小的缘故,提出用固定在铜排特殊位置上的单一芯片替代一整圈铁芯的电流测量方案。本文从霍尔传感器的基本原理出发,用有限元软件分析从实际角度考虑了霍尔芯片的摆放位置,并用试验验证了仿真的准确性。在此基础上,分析了干扰源对其产生的各种影响。最后得出结论:可以仅使用放置在特定位置上的霍尔芯片的方法测量特定铜排上的大电流,这样节省了大量体积。     

波浪补偿绞车稳态和动态特性的试验研究

在海上施工、科研考察和海洋平台等领域中广泛运用波浪补偿绞车技术。本文介绍了一种波浪补偿绞车组成、工作原理及试验方案。通过试验,分析了波浪补偿绞车开环和闭环控制下的稳态和动态特性,运用频率分析仪对波浪补偿绞车机、电、液系统的开环和闭环系统进行系统辨识,掌握了波浪补偿绞车机电液系统的近似传递函数。最后提出了试验应该注意的事项,以为工程实际提供试验研究和分析手段。     

基于粒子群遗传搜索算法的水下结构内部激励力源识别

文章针对水下弹性结构,提出一种识别结构内部激励力源的匹配场处理方法及基于结构辐射声场的广义拷贝场概念,并提出采用粒子群遗传融合搜索算法对最优力源强度进行匹配搜索。以水下自由声场中的单层圆柱壳体为研究对象,采用数值计算方法建立了结构辐射声场传递函数拷贝场,并对匹配搜索算法进行了数值仿真分析。在消声水池中进行了水下单层圆柱壳体辐射声场测试,将测试结果与拷贝场进行了匹配处理。仿真结果与试验结果均表明,这种力源识别匹配场处理方法可以有效地针对结构内部的力源强度进行分析排序,利用匹配识别的结果进行辐射噪声预报时,预报精度很高。     

基于移动热源的盘式制动器三维瞬态温度场仿真分析

以FSAE赛车前轮盘式制动器为研究对象,考虑了移动热源的影响,运用Ansys软件建立了其三维瞬态温度场模型。由此得到了一次紧急制动工况,不同初始车速制动盘的温度场分布以及其上不同位置节点温度的时间历程曲线。     

城乡居民家庭消费支出与阶层认同——基于CGSS2010的数据分析

运用STATA软件对2010年CGSS数据进行多元线性回归分析,用以探讨城乡居民的家庭消费支出对个体阶层认同的影响。研究发现家庭消费支出中的服装支出、交通通讯支出、耐用品支出、非个人自付医疗支出、文化娱乐支出及人情送礼支出对城乡居民的阶层认同具有积极影响,这也反映了消费在阶层认同中的重要作用。研究还发现:不同于已有研究,个体的阶层认同的他者取向并没有完全消失。