cationEducation and VocationEducatio

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Distributed and Redundant Design of Ship Monitoring and Control Network

The world trend in ship automation is to integrate the monitoring, intelligent control and systematic management of the instruments and equipments both on bridge and in engine room. The paper presents a design scheme of the ship integrated monitoring and operating system based on two layers distributed and redundant computer network. The lower layer network is the field bus network connected mainly by CAN bus; the upper one is the PC local network in TCP/IP protocol, which consisted of a database server, monitoring and operating computers, industrial computers and a set of switches. Distributed schemes are fully applied to both software and hardware. This paper specifically describes the composition, software distribution and redundant technology of the upper local network and gives some important sample codes for the implement of the redundant and distributed design. The technologies here have been proved in the many applications and it may be applied to other industrial fields.     

Analysis and Comparison of Range-Range Positioning Mode and Hyperbolic Positioning Mode

Three key factors are discussed, which affect positioning accuracy of range-range positioning mode and hyperbolicpositioning mode.Based on the error elliptical theory, the expressions of positioning error and of positioning geometric factor ofrange-range positioning mode and hyperbolic positioning mode are derived, and the positioning error and the blind positioningarea of two different positioning modes are analyzed. According to the requirement of navigation area, an optimum positional     

Building both friendship and trade bridges

The POrt Of BQSton 15 NeW巨ngland,S major full serviee Portand gatewayfor trade,aeeounting for aP-Proximatelyg,000」obsandeontributinganestimated$8 billion to the了egionaleeonomy ofthe NortheastUnitedstates. Thesix一stateNew Englandregion 15made uP ofthestatesof Mas3aehusetts,Conneetieut,Rhode lsland,Maine,NewHamPshire,and论rmont.New Englandlseonsideredto be oneof the mostafflUentregionsin the USA.The Port of Bostonhas a strong lmPort and exPortmarketwithaPProxirnately 60%of New…     

河海大学Water Science and Engineering创刊

国家新闻出版总署日前正式批复，同意河海大学创办英文期刊Water Science and Engineering（水科学与水工程）。该刊为季刊，面向国内外公开发行，国内统一连续出版物号为：CN32—1785／TV。     

Navigator and diplomat Zheng He remembered

The year 2005 witnesses a number of large-scalecommemorative activities to celebrate the great navigator anddiplomat Zheng He (1371-1435) all over the country. Widelyconsidered to be an important person in the history of Chinesenavigation, Zheng He led hi…     

Review and pros-pects ofr China''''s economy

The Chinese economy grew 8 per cent in 2002. The speedy growth of China's economy in 2002 was fuelled by booming exports and the central government efforts to stimulate domestic demand. Preliminary figures from the National Bureau of Statistics suggest that the country's gross domestic product (GDP) reached 10.2 trillion yuan (US$1.23 trillion) in 2002, an increase of 8 per cent from the previous year. 2002 is a year for which we have a whole host of things to rejoice over, to remember, and to toast. The momentous 16th National Congress of the Communist Party of China, which selected a new leadership for our country, was the biggest event on China's     

Review and pros pects for China economy

The Chinese economy grew 8 per cent in 2002. The speedy growth of China‘s economy in 2002 was fuelled by booming exports and the central government efforts to stimulate domestic demand.     

Cooperative path following control of UAV and USV cluster for maritime search and rescue北大核心CSCD

［Objectives ］ This paper studies a three-dimensional (3D) cooperative path-following control problem in the process of maritime search and rescue for a heterogeneous unmanned cluster system composed of unmanned aerial vehicles (UAVs) and unmanned surface vehicles (USVs).［Methods ］ First, kinematic models of the UAVs and USVs are established under a fixed coordinate system and body coordinate system. In order to design a 3D path-following controller suitable for motion control, an air coordinate system is established, and the path tracking error models of the UAVs and USVs are established in the Serret-Frenet coordinate system. Next, a 3D line-of-sight (LOS) guidance law is designed at the kinematic level, and a cooperative path-following control method suitable for heterogeneous clusters of marine vehicles is proposed, allowing the UAVs and USVs to track the preset parameterized path. Finally, the stability of the control system is analyzed based on the Lyapunov stability theory.［Results］The simulation results verify the effectiveness of the proposed cooperative path-following control method for heterogeneous clusters of marine vehicles.［Conclusions］The results of this study can provide references for maritime search and rescue by using the proposed cooperative path-following control method. © 2022 Journal of Clinical Hepatology. All rights reserved.     

Asian Economic Recovery and Chinese Economic Acceleration

The economies of the Asian region have recovered quickly since the second half of 1999, and the sphere of recovery is extending further. Financial market confidence returns in most economies that have been affected by the crisis. It is shown by not only the powerful export, but also the growth of domestic demand and intra-regional trade and the industry of both service and real estate begin to bottom out, etc. In the field of macro-economic control, Asian countries have made remarkable achievements in     

Problems and measures after China''''s WTO entry

China's accession to the World Trade Organization (WTO) will not only benefit the country's economic development, but also have far-reaching influences on Chinese society, pointed out a report released by the Development Research Centre under the State Council at a recent forum. WTO membership will accelerate the modernization of Chinese society and have a positive effect on people's lives. However, it may also exacerbate some existing problems such as unemployment and the widening gap between social classes, said the report. The government is urged to draft specific laws and policies to deal with coming challenges, ease potential social conflicts and     

Uncertainty quantification of Delft catamaran resistance,sinkage and trim for variable Froude number and geometry using metamodels,quadrature and Karhunen–Loève expansion

A framework for assessing convergence and validation of non-intrusive uncertainty quantification (UQ) methods is studied and applied to a complex industrial problem in ship design, namely the high-speed Delft Catamaran advancing in calm water, with variable Froude number and geometry. Relationship between UQ studies and deterministic verification and validation is discussed. Computations are performed using high- (URANS) and low- (potential flow) fidelity simulations. Froude number has expected value and standard deviation equal to 0.5 and 0.05, respectively, on a truncated normal distribution. Geometric uncertainty is related to the research space of a simulation-based design optimization, and assessed through the Karhunen–Loève expansion (KLE). Monte Carlo method with Latin hypercube sampling (MC-LHS) is used to compute expected value, standard deviation, distribution and uncertainty intervals for resistance, sinkage and trim. MC-LHS with CFD is used as a benchmark for validating less costly UQ methods, including MC-LHS with metamodels and standard quadrature formulas. Gaussian quadrature is found the most efficient method; however, MC-LHS with metamodels is preferred since provides with confidence intervals and distributions in a straightforward way and at reasonably small computational cost. UQ results are compared to earlier deterministic single- and multi-objective optimization; reduced-dimensional KLE studies for geometric variability indicate that stochastic optimization would not be of great benefit for the present problem.     

Flexural wave bandgap and isolation characteristics of vibration and sound in periodic sandwich plates北大核心CSCD

[目的]旨在研究轻质夹芯板弹性波的传播规律与减振降噪机理。[方法]采用有限元方法结合布洛赫定理,对周期性夹芯板色散关系与弯曲波带隙特性进行研究,分析振动传输特性和声传输特性,研究轻质夹芯板减振降噪特性,并对轻质夹芯板振动传递衰减特性进行实验验证。[结果]研究结果表明,由于布拉格(Bragg)散射调制作用,轻质夹芯板在特定频段存在弯曲波带隙,弯曲振动带隙频率范围内具有良好的减振降噪效果。[结论]轻质夹芯板结构参数对弯曲波带隙具有显著的调节作用,为舰船结构振动噪声控制与声隐身设计提供了新的技术途径。     

Difference in ship motion and wave load in long and short crested irregular waves北大核心CSCD

[Objective]To investigate ship motion and load responses in realistic 3D waves and overcome the limitations of the traditional 2D wave assumption, this paper develops a method for predicting ship motion and load responses in short-crested waves. [Method]The long- and short-term responses of ship motion and load in long- and short-crested waves are numerically predicted using the spectral analysis and statistical probability methods, respectively. The influence of directional function on ship response is also numerically analyzed. Moreover, tank model tests and a large-scale model sea trial are comparatively conducted to validate the difference between ship response and statistics in long- and short-crested irregular waves. [Results]The results show that when navigating against the waves in the same sea condition, the long-crested wave assumption overestimates the statistical mean value of ship load response, but underestimates extreme load in real seas. For long-crested waves, the ship motion and acceleration power spectrum is concentrated around a certain frequency band. [Conclusion]Ship motion and load responses in realistic 3D waves are significantly different from those in 2D long-crested waves. The directional function of short-crested waves also has a significant effect on ship motion and load responses. © 2023 The Author(s).     

Inland container terminal—function and rationale

Increasing commercial and recreational pressures on urban waterfront lands, growing demand by seaports for back-up areas and changes in cargo-distribution concepts have caused the relocation of several port functions and the establishment of inland container terminals.     

On Wavemaking Characteristics of Catamarans and Trimarans

A method for calculating wavemaking resistance of a multihull vessel and corresponding computer program have been developed. The wavemaking characteristics of catamarans and trimarans were analysed based on theoretical calculations. The ranges of Froude numbers at which beneficial and adverse interferences occur, have been indicated and the interference mechanism been preliminarily shown as well.