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871.
SUNJing-hua ZHANGXin-lu 《船舶与海洋工程学报》2003,2(1):71-75
A simple rate equation model for 2μm Tm, Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power are obtained. The present model provides a straightforward procedure to design the laser resonator and the optical coupling system for optimization. At the same time, the experimental results are reported. At room temperature the slope efficiency is 22.4% and the typical lasing threshold is about 328mW. The theory is in good agreement with experiment. 相似文献
872.
Peter M. P. Muirhead 《WMU Journal of Maritime Affairs》2004,3(2):139-158
This paper examines the impact of new technology on MET institutions in the 21st century and discusses to what extent global MET institutions can enhance and enrich traditional practices through access
to new technology and the use of innovative teaching and assessment methods within a sustainable and achievable framework.
It notes the diverse standards and access to new technology by MET institutions across the globe and discusses the implications
for them if they are to remain competitive and viable. The paper concludes that maritime institutions can benefit from the
use of new technology, but only through rational planning and sustainable staged growth. A series of continua of technical
development is provided to assist institutions, from the smallest to the largest, to plan for technical development and growth
in a rational and feasible way. 相似文献
873.
Dynamic analysis of multibodies system with a floating base for rolling of ro-ro ship caused by wave and slip of heavy load 总被引:2,自引:0,他引:2
SHEN Qing LI Yue and CHEN Xu-jun The Engineering Institute of Engineer Corps PLA University of Science Technology Nanjing China 《船舶与海洋工程学报》2003,2(2):17-24
Common effect of wave and slip of internal heavy load will make rolling of the roll-on ship serious. This is one of the important reasons for overturn of ro-ro ships. The multibodies System with a floating base is composed of ro-ro ship and slipping heavy load. This paper takes the rolling angle of the ship and the transverse displacement of the heavy load on desk as two freedoms. Making use of analysis of apparent gravitation and apparent buoyaney, the wave rolling moment is derived. By use of dynamic method of multibodies system with a floating base, dynamic equations of the system are established. Taking a certain channel ferry as an example, a set of numerical calculation have been carried out for rolling response of the ship and displacement response of the slipping heavy load under common effect of synchro-slipping heavy loads and wave. 相似文献
874.
ZHAO Shu-qin SHI Xiao-cheng SHI Yi-long and BIAN Xin-qian College of Power Nuclear Engineering Harbin Engineering University Harbin China 《船舶与海洋工程学报》2003,2(2):67-71
This research is on horizontal plane motion equations of Air Cushion Vehicle (ACV) and its simulation. To investigate this, a lot of simulation study including ACV‘s voyage and turning performance has been done. It was found that the voyage simulation results were accorded with ACV own characteristic and turning simulation results were accorded with USA ACV‘s movement characteristic basically. 相似文献
875.
Pottengal Mukundan 《WMU Journal of Maritime Affairs》2003,2(2):167-180
This paper sets out the nature, scale and geographical locations of attacks against vessels today. Numerous examples in the paper highlight the worldwide nature of these attacks, the violence and differences in modus operandi and targets. The information is drawn from the International Maritime Bureau’s (IMB) Piracy Reporting Centre in Kuala Lumpur. Against this background, it briefly discusses issues of definition and response, including some technological devices, which can help locate hijacked vessels and deter unlawful boarding. The paper concludes with some practical thoughts on dealing with international crime, the victims of which, through the nature of their work have to travel beyond national boundaries, and so do not always attract the support of and commitment from national governments and law enforcement agencies where the attacks take place. 相似文献
876.
Mümin Tolga Emirler Levent Güvenç Bilin Aksun Güvenç 《International Journal of Automotive Technology》2018,19(2):359-367
This paper is on the design of cooperative adaptive cruise control systems for automated driving of platoons of vehicles in the longitudinal direction. Longitudinal models of vehicles with simple dynamics, an uncertain first order time constant and vehicle to vehicle communication with a communication delay are used in the vehicle modeling. A robust parameter space approach is developed and applied to the design of the cooperative adaptive cruise control system. D-stability is chosen as the robust performance goal and the feedback PD controller is designed in controller parameter space to achieve this D-stability goal for a range of possible longitudinal dynamics time constants and different values of time gap. Preceding vehicle acceleration is sent to the ego vehicle using vehicle to vehicle communication and a feedforward controller is used in this inter-vehicle loop to improve performance. Simulation results of an eight vehicle platoon of heterogeneous vehicles are presented and evaluated to demonstrate the efficiency of the proposed design method. Also, the proposed method is compared with a benchmark controller and the feedback only controller. Time gap regulation and string stability are used to assess performance and the effect of the vehicle to vehicle communication frequency on control system performance is also investigated. 相似文献
877.
Vincenzo Alfieri Giuseppe Conte Carmen Pedicini 《International Journal of Automotive Technology》2018,19(3):405-412
The objective of this study is to investigate a nonlinear model-based multivariable (MIMO, Multi Input Multi Output) technique to decouple actuators interaction and to reduce the calibration effort, while increasing control performances, above all in transient conditions, and robustness with respect to model uncertainties and system parameter variations. The presented control technique is based on the development of a nonlinear dynamical physical model of the diesel air and charging system. Feedback Linearization control is then applied to decouple actuators’ interactions and compensate for nonlinearities. A new set of virtual inputs are defined inverting the system differential equations. Relation among the new virtual inputs and the outputs is purely linear and decoupled, meaning that each virtual input affects linearly only one output. Moreover, a linear control block is added to guarantee transient and steady state performances and closed loop robustness. The proposed control approach has been validated through small diesel engine dyno and vehicle activities. Transient test bench maneuvers show that the control is able to coordinate the actuators in order to fulfill the targets and to guarantee similar performances in different operating points. In addition the robustness to environmental changes has been demonstrated by vehicle tests at different ambient conditions. 相似文献
878.
WANGDong LIZhuang-yun ZHUYu-quan 《船舶与海洋工程学报》2003,2(1):35-40
Water hydraulic systems have provoked major interest because of the human friendly and environmental safety aspects. Piston pump is one of the most frequently used hydraulic units in recent engineering technique. In water hydraulic piston pump, poor lubrication is more likely to happen than in oil hydraulic one because of difference in properties between water and oil. So there are some key problems such as corrosive wear and erosion, which are investigated briefly. Many new materials have been developed, which give longer life expectancies with water without corrosion and erosion. A new type of seawater hydraulic piston pumps with better suction characteristics had been developed at HUST. Much of this research has concentrated on new materials, structure and experiments, which are also specially introduced. 相似文献
879.
The energy distribution model of motion blurred star point is analyzed. The distribution of the star point approximates to a two-dimensional (2D) Gaussian distribution under degeneration. Two multi-parameter nonlinear Gaussian fitting methods (GFMs) are proposed, and the relationship between fitting parameters and motion blur parameters is analyzed. Estimation of the parameters of motion blur by fitting parameters is calculated to realize the error compensation of the motion blur. The simulation results show the effectiveness and accuracy. 相似文献
880.
Based on geomorphological criteria, the Coastal Habitat Management Plan (CHaMP) for the Solent identified some 4,800 hectares of land potentially suitable for the creation of intertidal habitat, principally saltmarsh, through the use of managed realignment. Using “constraint mapping,” this study set out to illustrate that limitations to habitat re-creation through inundation are not merely geomorphological in nature. Indeed, a broad range of social, political, legal, technical, and economic constraints exist and must be evaluated in conjunction with physical parameters if the objectives of the European Birds and Habitats Directives are to be met, and so that future coastal defense policies ensure maintenance of the “favorable conservation status” of designated sites. A numerical filter system has been used to re-evaluate individual sites to establish “realistic” opportunities for compensatory saltmarsh creation in the Solent. As a result of taking into account wider socioeconomic constraints, it is clear that fewer areas are available for habitat creation purposes than were initially identified in the Solent CHaMP study. 相似文献