磁控电抗器在北良港变电所无功自动补偿装置中的应用

北良港#3变电所所供电力变化较大,导致其功率因素极低,为此进行了改造,使用了磁控电抗器。介绍了#3变电所的概况。提出了改造要达到的目标,详细介绍了改造方案,作了经济性分析。这一方案达到了节能降耗的目的。     

中国海事推演IMO自愿审核机制的成效分析

国际海事组织从推动全球协调、统一履行国际海上人命安全公约（SOLAS）等六个重要公约的角度,建立并实施了自愿审核机制。中国政府积极参加该机制,于2009年11月7—18日自愿接受了IMO审核并取得良好的审核结果。通过审核工作,较好展现了我国政府履约的良好形象。维护了国家航运利益,促进了中国海事管理事权组织方式的改进,丰富和发展了大国海事公共治理内涵,也为全球协调统一履约发挥了积极的推动作用。海事系统通过迎审准备和接受审核,调整了理念,完善了战略规划,加强了能力建设,推动中国海事管理规范化、科学化、制度化发展。     

电力系统谐波抑制的方法研究与发展趋势

随着电力电子技术的发展,电力电子装置得到了广泛应用。然而,在应用这些设备的同时,它们向电网注入了大量谐波,使电网电能质量受到严重污染。对电力系统谐波产生的原因及其带来的危害进行了阐述,详细介绍了现有的谐波抑制方法,并对各种方法优缺点进行了比较分析。最后,对谐波抑制技术的未来发展趋势进行了展望。     

超高加筋土挡墙稳定性研究

文中根据工程实践,对超高加筋土挡墙的稳定性进行了深入地研究。给出了针对高落差挡墙的设计方案,阐述了加筋土挡墙稳定性验算的方法和原理,系统地分析了加筋土挡墙的内部稳定性和外部稳定性,最后通过工程实例,验算了两阶超高加筋土挡墙的稳定｜陛,给出了详细的计算结果,为加筋土挡墙的设计提供了理论依据和技术支持。     

卸船机小车卷筒联轴器窜动处理及改造

珠海电厂卸船机小车卷筒联轴器窜动的重大缺陷影响了安全生产。分析了缺陷的表现,介绍了处理缺陷的多项办法。改造后,实际使用效果较好。解决了设备本身存在的设计缺陷,提高了设备的安全性。可供借鉴。     

平台上层建筑局部振动预防方法研究

介绍了一种针对平台上层建筑局部振动的预报方法。以宏华海洋研发的一型自升式多功能支持平台为例,利用有限元法,预报其上层建筑局部振动。预报中除考虑了常规主机及推进器激振频率外,还考虑了泥浆泵及大型风机的影响。通过计算发现了上层建筑结构多处局部结构固有频率位于激振区间内。通过结构修改,改良了局部振动性能,预防了共振的产生,达到了预期目标。     

十五相感应电机带螺旋桨负载的矢量控制仿真研究

推导了十五相电机的数学模型,并建立了其仿真模型。分析了螺旋桨非线性负载特性,建立了螺旋桨的数值仿真模型。进行了十五维广义派克变换的推导并研究了变换矩阵的物理意义,在此基础上设计了十五相电机转子磁场定向矢量控制策略。通过MATLAB/Simulink中的仿真实验,验证了多相电机模型和螺旋桨模型的合理性,也验证了多相电机矢量控制策略的有效性。     

基于可重构技术的数字系统再生设计

为了适应数字系统再生设计的需要,设计了一个基于可重构模块的辅助学习系统,完成了对特定模块的功能复制。通过微指令跟踪的方法,获得了研究对象的全部接口数据。并通过软件方法对接口数据进行约简处理,使用VHDL语言编辑配置文件,配置可重构模块。设计了一个实用的并行接口电路板,完成了辅助学习系统的功能切换。最后通过对某型计算机的辅助运算模块的再生设计实例,验证了方法的有效性,并通过对比试验完成了对故障板的故障诊断任务。     

基于OpenGL的雷达显示器仿真

雷达显示器仿真是雷达系统仿真的重点和难点。在简要介绍OpenGL技术和雷达显示器的基础上,提出了利用OpenGL对P型雷达显示器进行仿真的思想,详细介绍了余辉扫描和目标点迹的仿真方法。对于余辉扫描,通过数学建模提出了实现途径,并得出了时间衰减常数和扫描周期的计算公式。对于目标点迹,提出了角度换算和目标位置的计算公式,并实现了点迹的余辉效果。结果表明,该方法达到了很好的仿真效果。     

一种基于场桥的钢丝绳更换新工艺

为了缩短轮胎式集装箱起重机(简称场桥)的钢丝绳替换时间,为此,设计了新型的钢丝绳固定装置,采用了新的换绳工艺。分析了影响钢丝绳换绳时间的原因。介绍了钢丝绳固定装置改造的具体办法和装绳工艺的改进。运行实践证明,改造达到了预期效果。     

Studying port selection on liner routes: An approach from logistics perspective

The research aims to study the port selection in liner shipping. The central work is to set up a model to deal with port choice decisions. The model solves three matters: ports on a ship’s route; the order of selected ports and loading/unloading ports for each shipment. Its objective is to minimize total cost including ship cost, port tariff, inland transport cost and inventory cost. The model has been applied in real data, with cargo flows between the USA and Northern Europe. Afterwards, two sensitive analyses are considered. The first assesses the impact of a number of port calls on the total cost which relates closely to the viability of two service patterns: multi ports and hub & spoke. The second analyzes the efficiency of large vessels in the scope of a logistics network. The overriding result of this research is to indicate the influence of logistics factors in the decision of port choice. The research emphasizes the necessity to combine different factors when dealing with this topic, or else a result can be one-sided.     

Vortex-induced vibration of a tension leg platform tendon: Multi-mode limit cycle oscillations

This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, analyzed using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation (lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency.     

如何提高"条条管理"单位的信息化水平

本文就“条条管理”单位的性质入手,探讨了如何提高“条条管理”单位的信息化水平。全文分五个部分。首先是分析“条条管理”单位的性质,以及其对信息化的影响。第二至四部分,分别从信息化建设、信息化教育和信息化维护三个方面进行探讨。第五部分,是对“条条管理”单位在信息化方面进行一些展望。     

Incident reporting in Finnish shipping companies

The purpose of the International Safety Management Code (the ISM Code) is to promote safety culture in the maritime industry. Learning the lessons from incidents should help to improve safety performance since incidents and accidents can share the same root causes. The aim of this paper is to take a closer look at incident reporting in the Finnish shipping industry, to study the reasons for poor incident reporting and to suggest improvements to increase reporting. The paper consists of a literature study, which focuses on previous studies concerning incident reporting, and an interview study, which focuses on Finnish shipping companies and their personnel. The interview study confirmed that incident reporting does not function properly within the Finnish maritime industry. The maritime personnel have an occupational culture which is incompatible with the rule-based safety management approach provided by the ISM Code. The willingness to report incidents could be increased if all seafarers were involved in the reporting process and the preparation of corrective actions. In addition, the reporting procedures should be streamlined and developed to a more user-friendly direction.     

The value of options for time charterparty extension: an artificial neural networks (ANN) approach

The most frequently associated options in the physical shipping market are options to extend the charter period on time charters and additional shipment options on contracts of affreightment. The value of freight options, in practice, is estimated mostly by referring to forward curves. An option on freight has different properties from its financial counterparts, and the straightforward adoption of theoretical models does not produce promising results. In this paper, extension options, which have the property of options on futures, were transformed into regular European options before the application of the Black-Scholes model (BSM). The efficient market hypothesis, which justifies the parity of the performance of a long-term charter to that of repetitive short-term charters, worked as the basis for the transformation. The option values determined by the BSM were compared with actual realized values. Additionally, the artificial neural networks (ANN) was employed to derive the option values. This study is meaningful as the first-time application of both the closed-form solution and the ANN to the valuation of physical freight options. The research results can contribute to the quality of chartering decisions. The results could also be used in quantifying credit risk, as extension options tend to be granted to charterers with more creditability.     

基于分层系数法与混合比法的长江口盐淡水混合规律研究

采用长江口4条入海汊道3个月的水文测验资料,研究长江口的盐度分布格局和盐淡水混合情况,运用分层系数法和混合比法对长江口实测盐度数据进行分析。结果表明:北支汊道的盐度最高,洪、枯变幅大,全年均为垂向均匀混合型;南支3条汊道盐度从高到低依次为南槽、北槽、北港;盐淡水混合强度从高到低依次为南槽、北槽、北港,这与长江口北港分流量大于北槽、北槽分流量大于南槽的格局相对应;枯季的混合强度大于洪季,大潮的混合强度大于小潮。盐淡水的混合强度呈周期性变化,涨急前后垂向混合程度最大,涨潮的混合强度高于落潮时的混合强度。     

On the use of the autocorrelation function to identify the damage in the side shell of a ship''s hull

When structural damage occurs, the dynamic characteristics of the structure changes correspondingly. This can be used to detect damage occurrence. In this paper, an autocorrelation function was utilized to identify damage in the side shell of ship structures using a combination of experimental and numerical studies. A stiffened plate was used to model the side shell of a ship structure. The damage was simulated by a cut in the longitudinal near the transverse member. The cut was made using a hacksaw. An experimental study using modal testing methods was carried out to measure the random response time history of the undamaged and damaged stiffened plate model. The random response time history was used to obtain its autocorrelation function and its random decrement signature. The autocorrelation function was then compared with the random decrement signature. Finite element models were developed for the stiffened plate, in the undamaged and damaged conditions. The random responses of the model were used to obtain the autocorrelation functions. The autocorrelation functions obtained numerically were compared to the ones obtained experimentally. The results indicate that the autocorrelation functions can be used to identify the occurrence of damage in the stiffened plate model.     

空泡闭合区压力特性试验研究(英文)

The most complicated component in cavitating flow and pressure distribution is the flow in the cavity closure line. The cavitating flow and pressure distribution provide critical aspects of flow field details in the region. The integral of pressure results of the hydrodynamic forces, indicate domination in the design of a supercavitating vehicle. An experiment was performed in a water tunnel to investigate the pressure characteristics of the cavity closure region. Ventilation methods were employed to generate artificial cavity, and the ventilation rate was adjusted accordingly to obtain the desired cavity length. An array of pressure transducers was laid down the cavity closure line to capture pressure distribution in this region. The experimental results show that there is a pressure peak in the cavity closure region, and the rise rate of pressure in space tends to be higher in the upwind side when the flow is non-axisymmetric. The transient pressure variations during the cavity formation procedure were also present. The method of measurement in this paper can be referenced by engineers. The result helps to study the flow pattern of cavity closure region, and it can also be used to analyze the formation of supercavitating vehicle hydrodynamics.     

舰船全寿期配置管理及其编码映射技术研究

舰船全寿期各配置视图,既是全寿命优化设计的结果,又是实现舰船预期功能并保证这些功能有效实施的关键技术.为保证配置的唯一性和处理方便,配置是用各主要编码来表达的.本文所提出的各配置之间的算法乃是实现配置自动处理的基础.舰船全寿期配置管理是实现各配置视图生成、相互映射、配置更改及其状态跟踪技术的综合应用,亦是保证舰船质量和有效使用及全寿期信息共享的核心.     

一新型深吃水平台的概念设计(英文)

The authors analyzed requirements for a new deepwater platform, from conceptual design to hydrodynamic analysis. The design incorporated Deep Draft Multi-Spar (DDMS) that allowed easy fabrication, reduced costs, and provided favorable motion performance. It also provided a dry tree system and other benefits. The conceptual design process included dimension estimation, general arrangements, weight estimation, weight distribution, stability analysis, etc. A high order boundary element method based on potential theory and the modified Morison equation was used to predict the hydrodynamic and viscous effects of this new concept platform. The response amplitude operators (RAOs) were acquired and compared with those of a typical Truss Spar. The response of the platform to the JONSWAP spectra of 3 different extreme ocean conditions was analyzed to evaluate the seakeeping ability of the new concept. The results revealed favorable motion performance due to all the degrees of freedom available.