Computerised development control and approval system for City Hall of Kuala Lumpur

This paper will discuss the computerised development control and approval system being developed for the Planning and Development Control Department. City Hall of Kuala Lumpur, with stress on the GIS architecture developed within the system. The prospects and challenges towards implementation of the system are also discussed.     

锚泊辅助动力定位系统推力器故障模式影响分析

锚泊辅助动力定位是将锚泊定位和动力定位相结合的一种新型位置控制系统。以某深水半潜式钻井平台为例,通过时域模拟分析了两个推力器失效模式对平台锚泊辅助动力定位系统定位精度、功率消耗及缆绳张力的影响。分析结果可以看出,深水作业时平台同一配电板上两推力器失效对平台水平偏移有很大影响,可通过减小或取消失效推力器相邻推力器的禁止角及拉紧迎风缆并松弛背风缆的方法来减小平台偏移,节约功耗,为动力定位系统的故障模式与影响分析提供了参考。     

Voigt regularization for the explicit time stepping of the Hall effect term

This article studies the stabilization of the explicit time stepping methods for Hall Maxwell and incompressible Hall MHD equations. Since the Hall effect term contains two spatial derivatives, classical time-stepping schemes result in very restrictive CFL condition. We consider weakening the restrictive time step condition via Voigt regularization. We establish the energy stability result and validate our approach numerically. Numerical experiments demonstrate that we are able to take larger time steps, compared to classical schemes, at additional, negligible computational cost.     

A Hall MHD model to study energetic charged particle events produced during fluctuations in the interplanetary magnetic field intensity

Energetic charged particles, which are often observed in solar active regions, may be also produced in interplanetary space due to the decoupling of ions and electrons in plasma. The Hall term in general Ohm's law is generally thought to be responsible for the decoupling of electrons and ions in plasma during magnetic reconnection. In this paper, a Hall MHD model is developed to study energetic charged particle events produced during fluctuations in the interplanetary magnetic field intensity. Two energetic charged particle events are used to test this model. It is concluded that the Hall effect does not only play the important role in the process of magnetic reconnection, but also in energetic charged particle events produced during fluctuations in the interplanetary magnetic field intensity.     

喉部结构不对称的微喷管数值计算

以FLUENT6.1软件为工具,利用湍流k-ε模型,求解二维稳态可压缩N-S方程,模拟了微喷管内的超音速流动,分析了喷管喉部结构不对称对喷管流场与喷管出口推力的影响。这种喉部结构不对称由于喉部上下顶点在x方向上偏离一定距离所造成。数值计算结果表明,喷管喉部上下顶点在流体流动方向的不对称,将导致喷管内部流体流场不平衡性,诱导喷管内部产生康达效应,使得喷管出口的x方向推力减小,y方向产生了多余的推力。     

水下机器人推力器布置及控制仿真研究

针对自治水下机器人(Autonomous underwater vehicle,AUV)推力器布置和控制仿真的困难性及以往电机仿真难以进行的缺点,提出1种进行多推力器运动仿真的方法,该方法建立的模型克服了推力器推力控制系统不能与电机结合的问题,能较好地反映推力器布置和电机的响应情况,可为AUV的运动控制、布置设计及控制系统开发等提供验证模型.针对流线型AUV CRanger-2的推力器布置情况,在对其建立推力器模型的基础上,利用模型对设定推力下的推力器控制进行仿真.仿真结果表明:该方法能够有效地模拟推力器布置既定情况下的电机运动与推力控制,可为水下机器人控制策略优化提供仿真平台.     

基于霍尔三维模型的气象工程项目管理方法

霍尔三维模型为工程项目管理提供了一种系统化的思维模式.以我国气象工程中综合气象观测系统运行监控平台(ASOM)开发项目为实例,结合气象工程项目的实际特点,从5个阶段的时间维度、7个步骤的逻辑维度和10个方面的知识维度对我国气象工程项目的霍尔三维模型进行了尝试性研究,结果具有较好适用性.研究结果可作为我国气象工程项目的管理依据,同时可为其他行业基于职能式管理模式的项目管理工作提供参考.     

Ship propulsion in waves by actively controlled flapping foils

Flapping wings located beneath or to the side of the hull of the ship are investigated as unsteady thrusters, augmenting ship propulsion in waves. The main arrangement consists of horizontal wing(s) in vertical oscillatory motion which is induced by ship heave and pitch, while rotation about the wing pivot axis is actively controlled. In this work we investigate the energy extraction by the system operating in irregular wave conditions and its performance concerning direct conversion to propulsive thrust. More specifically, we consider operation of the flapping foil in waves characterised by a spectrum, corresponding to specific sea state, taking into account the coupling between the hull and the flapping foil dynamics. The effect of the wavy free surface is accounted for through the satisfaction of the corresponding boundary conditions and the consideration of the wave velocity on the formation of the incident flow. Numerical results concerning thrust and power coefficients are presented, indicating that significant thrust can be produced under general operating conditions. The present work can be exploited for the design and optimum control of such systems extracting energy from sea waves for augmenting marine propulsion in rough seas, with simultaneous reduction of ship responses offering also dynamic stabilisation.     

地球等离子体片中磁泡对地面磁场的扰动

观测到的爆发流（Busty Bulk Flows,简称为BBFs）有很多主要特征都可以用磁泡图像描述 . 磁泡模型认为电离层中绝大部分电势降落都发生在磁泡中,据此可以估算它周围的霍尔电 流及其在地面引起的地磁扰动. 将本文结果与SMA（Scandinavian Magnetometer Array）雷 达阵列观测的BBFs的特征进行比较之后,发现二者符合得很好. 这表明BBFs与磁泡在引起地 面磁场扰动上的表征是一样的,暗示BBFs很可能就是磁泡.     

Hall effect on magnetic reconnection at the Earth's magnetopause

We analyze in situ observations of magnetic reconnection at the Earth magnetopause to estimate the importance of the Hall current during the merging of interplanetary and magnetospheric magnetic field lines. The reconnection process is studied through numerical simulations, integrating the Hall MHD equations in 2.5 dimensions. A large influence of the Hall effect is found, which can be measured by a significant increase of the reconnection rate.