Dissolved organic matter in shelf waters off the Ría de Vigo (NW Iberian upwelling system)

Net in situ production and export of dissolved organic carbon (DOC) and nitrogen (DON) have been studied in shelf waters off the Ría de Vigo (NW Spain), as part of a comprehensive hydrographic survey carried out from September 1994 to September 1995 with a fortnight periodicity. DOC and DON correlated well (r=+0.78), the slope of the regression line being 12.0±0.7 mol-C mol-N⁻¹, about twice the Redfieldian slope of particulate organic matter, 6.5±0.2 mol-C mol-N⁻¹ (r=+0.95). Labile DOC and DON accumulated in the upper 50 m during the upwelling season (March–September), mainly after prolonged periods of wind relaxation, when horizontal flows were reduced. This labile material represented 50% and 35% of the total (dissolved+particulate) organic carbon and nitrogen susceptible of microbial utilisation, which assert the key contribution of dissolved organic matter (DOM) to the export of new primary production in the NW Iberian upwelling system. This surface excess in shelf waters appeared to be formed into the highly productive Ría de Vigo (a large coastal indentation) at net rates of 4.4 μM-C d⁻¹ and 1.3 μM-C d⁻¹ in the inner and outer segments of the embayment respectively, and subsequently exported to the shelf. Once in the shelf, simple dilution with the inert DOM pool of recently upwelled Eastern North Atlantic Central Water (ENACW) occurred. Eventually, the DOM excess produced during the upwelling season is exported to the adjacent open ocean waters by the coastal circulation. Conversely, during the unproductive downwelling season (October–February), the lowest DOC and DON levels were recorded and export was prevented by the characteristic downwelling front associated to the seasonal poleward slope current.     

The role of copepods in the Baikal ecosystem

This describes a study of the pelagic zone of Lake Baikal with particular reference to copepods. In addition the cycling of matter and energy in lacustrine basins is described.     

The combined effect of rain and wind on air–water gas exchange: A feasibility study

A series of experiments were conducted at University of Delaware's Air–Sea Interaction Laboratory to examine the combined effects of rain and wind on air–water gas exchange. During this study, ASIL WRX I, a combination of 3 rain rates and 4 wind speeds were used, for a total of 12 different environmental conditions. The SF₆ evasion method was used to determine the bulk gas transfer velocities, and airside profiles of wind and CO₂ were used to estimate flux–profiles of momentum and carbon dioxide. In addition to measurements of fluxes with and without rain in a wind–wave boundary layer, measurements of wave properties were also obtained. Rain is shown to alter the wind profile in the flume, and dampen surface waves. Also, SF₆ evasion indicates that with the present experimental setup, for most of the experimental conditions, rain and wind combine linearly to influence air–water gas exchange. Flux–profile relationships for marine atmospheric boundary layers, which were performed to scale up to field measurements, were explored by a comparison between SF₆-derived bulk fluxes and airside CO₂ profile measurements.     

Numerical method of electromagnetic pulse response of conductor with complex load北大核心CSCD

[Objectives]Electromagnetic pulse can seriously affect and even destroy naval shipborne electronic information systems, weapons, equipment and so on. Due to the complexity of the antenna port load circuit, it is necessary to formulate a numerical method which can easily obtain the antenna load current. [Methods]The induced current of the terminal is obtained on the basis of the finite-difference time-domain (FDTD) and Holland model. According to the Thévenin equivalent circuit, the conductor is equivalent to the voltage source to realize decoupling between the conductor and load end, and the load circuit is solved using Simulink software.[Results]Compared with the traditional terminal model, this method is simple and feasible for high-order circuit processing. The effectiveness of the model is verified using non-linear elements and parallel capacitors and resistors as the load respectively. The results show that the calculation results of this method are consistent with those of the traditional methods. Finally, the antenna of the end-connected protect- or is calculated. The results show that the lead inductance caused by the installation of the protector is an important factor affecting the protection performance.[Conclusions]The method proposed in this paper can greatly reduce the simulation complexity of the coupling current of an antenna with a complex load, giving it useful reference value for the field of ship electromagnetic pulse protection design. © 2023 Editorial Department of Chinese Journal of Ship Research. All Rights Reserved.     

迎接STCW‘95公约的挑战

介绍了英国喀里多尼亚ＭａｃＢｒａｙｎｅ公司驾驶员与轮机员的培训模式,并对其进行了分析。     

Do mergers and alliances influence European shipping and port competition?

In Europe, ports are confronted with a closer integration in the maritime and shipping industries. The co-operation agreements can take several forms such as alliances and mergers among shipping lines, conferences, involvement of shipping companies in terminal management, and extending interests in inland transport of shipping companies. In this paper we give a brief overview of these different types of agreement and we examine the consequences of this evolution of the market structures in which ports and shipping companies have to operate. More specifically, attention goes to the competitive position of the port in this new environment. It is clear that the role of the port and the port authorities has to be redefined to guarantee that it remains a fully fledged player in this fast evolving integrated market.     

A model to identify airport hubs and their importance to tourism in Brazil

Air transportation in Brazil has been recently liberalized and one of the consequences of this process is the concentration of flights in a few hubs. During the years 2006-2007 two fatal accidents created unprecedented chaos in both land and air sides of the system with harmful consequences to tourism in Brazil. The consequences were more airport congestion and many episodes of flight delays and cancellations that lasted for several months. We argue that, among other factors, this state of blackout was a result of the increase in the degree of concentration in few airports, particularly Congonhas (in São Paulo) and Brasília. Using data obtained from a survey with Brazilian experts, a comparison was made with two existing methods (the one used by the US Federal Aviation Administration and the usual Herfindahl-Hirschman method) in order to calculate the number of hubs in Brazil. Due to the huge discrepancy obtained between data from the survey and the other two methods considered, a new mathematical method based on the Herfindahl-Hirschman Index was proposed to identify the number of hubs in a given network. Drawing from the examples of what happened to tourist destinations during and after the air transport crisis in Brazil, the article concludes discussing the need for a more accurate tool to identify and to monitor the concentration of flights at the Brazilian air transportation network and its importance to tourism.     

Outsourcing rural school transportation: A Brazilian handbook for practice at the municipal level

In Brazil, Rural School Transportation (RST) falls under the responsibility of state and municipal governments. However, there are no clear rules to guide the provision of this essential service. RST in Brazil is characterised by inefficient contracting practices, poor service control by school administration, and lack of legal instruments to penalise poor services, thus allowing operators to run services according to their own commercial criteria. In addition, payment is low, leading to the employment of old vehicles, lack of safety equipment, and non-convenient routes, among other aspects. As a result, school children provided with this service are subject to long travel time over large distances, and irregular and late services, coupled with poorly maintained roads. When children finally arrive at school they are tired, which often negatively affects their school performance and attendance, contributing to early school drop-out. In order to contribute to the improvement of school transportation quality, state and municipal authorities must develop the required organisational, planning, and regulatory skills. Accordingly, this article addresses the elements and the structure of a handbook that is being elaborated for local governments.     

Rural school transportation in emerging countries: The Brazilian case

The lack of proper policies for the rural environment, in contrast to the situation in the urban environment in Brazil, has prevented the rural population from benefiting from basic infrastructure and access to their rights as citizens. The poor school transportation conditions are large barriers to access and retention of pupils in schools. These poor conditions, with lack of comfort and high accident risks, result in long travelling hours to reach the school and lessen learning performance because the children arrive in the school tired and sleepy. The Brazilian Federal Government has adopted different programs and actions in order to overcome these difficulties and to improve school conditions in general. A new standard vehicle has been adopted, which will be fit for the harsh road conditions in the rural areas, and handbooks have been introduced to help the municipalities and their officials to plan and to contract school transport services. This paper provides an overview of the outlook for rural school transportation in Brazil, describing the operational conditions (including trip and vehicle conditions) and their users, as well as analysis on the effects on school performance, and also the role of the local and Federal governments.     

Analysis of the application and development of integrated electric power technology for unmanned ships北大核心CSCD

近年来,随着动力、信息等技术的不断发展,无人船在反水雷、反潜、电子战、海上安全、海上拦截等军用领域凸显出越来越大的优势。为此,首先阐述无人船及其动力技术的发展概况,明确综合电力系统已成为中大型无人船的重要发展趋势,然后介绍综合电力系统在有人/无人平台的应用情况,提出设备尺寸、重量和振动噪声控制等问题是综合电力系统应用于无人平台的研究重点,最后阐明无人平台综合电力技术的发展趋势,指出综合电力系统智能化运行、高性能电机材料、复杂电机系统信息感知、电力电子器件与系统、高性能电能变换和高效储能是无人平台综合电力技术的关键科学问题。