Intrusions of eastern North Atlantic central waters and phytoplankton in the north and northwestern Iberian shelf during spring

The influence of intrusions of eastern North Atlantic central water (ENACW) in the north and northwestern Iberian shelf on phytoplankton composition and abundance and on particle-size distributions of seston was analyzed using data collected on three extensive cruises during spring 1991 and 1992. Water with temperature and salinity values between 12.20 and 13.86 °C and between 35.66 and 35.98 psu, respectively, characteristics of the subtropical type of ENACW (ENACW_t), was detected in the upper 100 m of the water-column in all cruises, but particularly in the western coast in 1992. The highest salinity values of this water were found near the surface (0–100-m depth) and in early spring 1992, while minimum salinity values, and also minimum geographical extension, were found in late spring in both years. Phytoplankton blooms concentrated in frontal areas between different water types, with maximum intensity and extension in early spring.Using temperature and salinity characteristics, samples were classified in four groups corresponding to the major water types found in the region: Bay of Biscay central water (BBCW), two segments of ENACW of different salinity and surface water influenced by continental runoff. This classification was significantly confirmed by three independent discriminant analyses using hydrographic and chemical (dissolved nutrients and chlorophyll) variables, phytoplankton species abundance variables and particle-size concentration of seston variables. Phytoplankton blooms related to the presence of saline waters were characterized by the dominance of either chain-forming diatoms or a mixture of diatoms and phytoflagellates and high concentrations of seston. The diatom species dominating in saline waters were typical of upwelling-induced blooms occurring generally during summer. Blooms occurring in waters influenced by runoff also contained diatoms but in lower numbers than those of saline waters. Nutrients were not exhausted in the region, suggesting that phytoplankton populations were still in active growth. These results are interpreted taking into account the known variability in water-mass formation and in the poleward current driving ENACW_t along the shelf, and indicate that saline intrusions are a major feature affecting the distribution and composition of plankton in the spring in the southern Bay of Biscay, thus enlarging to a wider spatial scale their reported influence on the pelagic ecosystem.     

谈谈铝的软钎焊

铝的软钎焊看起来很简单，但在许多关键的地方需要严密的过程控制。粘着力强的氧化铝往往使通常的软钎焊显得很困难。由于铝合金钎料与通常的不同，要针对电腐蚀的影响，注意合金的选择。各种不同的铝合金、测     

高速列车用轨道制动装置

在市场经济条件下，发展俄罗斯的高速铁路运输业是很迫切的任务。由于客车运行速度的提高，与其他形式的高速工具相比，即使2站间的运输距离很长，铁路运输的竞争力也在不断增强。然而，摆在面前的突出问题是要提高列车运行的安全性，解决这个问题，在很大程度上取决于制动系统的工作效率和工作稳定性。     

Application of Sensitivity Analysis to the Development of High Performance Adaptive Hydraulic Engine Mounts

Summary In this paper, the sensitivity analysis is applied to the development of high performance adaptive hydraulic mounts. The analysis allows us to select the most effective design parameters for tuning an adaptive mount to different road and engine conditions. It is shown that in the low frequency road excitation, the upper chamber compliance and inertia of the fluid column in the inertia track are the most influential properties in changing the dynamic stiffness of the hydraulic mount. These properties for the high frequency engine excitations are the upper compliance and the inertia of the fluid column of the decoupler. For tuning the adaptive mount to different road and engine excitation, a global optimization technique is used to find the magnitude of the adjusting parameters to minimize objective functions in low and high frequency excitations. The results indicate significant improvement over conventional hydraulic mounts. It is further shown that when the upper compliance is used as the adjusting parameter, a simple on-off control which is triggered by the engine revolution and vehicle speed is sufficient for tuning the adaptive mount.     

Time Domain Model of the Vertical Dynamics of a Railway Track up to 5 kHz

The modelling of the vertical dynamics of a track at high frequencies requires rather complex approaches to take into account section deformations. Validation is usually made by comparing computed frequency responses with measured ones. In this study an experimental model of a railway track is proposed based on the analysis of recorded time histories of impact excitations and the corresponding vibrations of the rail with auloregressive (AR) techniques. Measurements are used not only as a convergence parameter that the model must approach, but are also entirely used to describe the dynamic behaviour of the rail in the frequency range 150 / 5000 Hz. Frequency response functions are reconstructed with a very high fidelity but the model obtained is not general, as it is applicable only to the measured track section under the hypothesis of linearity. The measurement details, the construction and the validation of the model are shown in this paper.     

Multimodal transport in the new millennium

Consignors of goods in international trade want their containers to move door to door whether by land, sea or air — smoothly, seamlessly and at predictable cost. What they actually get from the law is at best a jerky roller coaster: a series of contracts, one for each mode or stage of the journey, contracts with various people and with liability that varies too. All agree that the law should change but attempts to agree on an entirely new multimodal regime have failed. Recently attempts have been not to start again but to expand an existing and established regime. The latest of these, the UNCITRAL draft, is essentially maritime: it applies to the sea phase but and goes further to apply door to door except when its path is blocked by compulsory unimodal law. Has Venus at last arisen from the waves? And what will happen when Beauty meets the Beast in the form of CMR? This article addresses the problems that will be encountered by an ambitious amphibious instrument of this kind. — problems of integration, of compatibility with local legal culture, and of methodology.     

Application of Nonlinear Control Theory to Electronically Controlled Suspensions

This paper illustrates the use of nonlinear control theory for designing electro-hydraulic active suspensions. A nonlinear, “sliding” control law is developed and compared with the linear control of a quarter-car active suspension system acting under the effects of coulomb friction. A comparison will also be made with a passive quarter-car suspension system. Simulation and experimental results show that nonlinear control performs better than PID control and improves the ride quality compared to a passive suspension.     

Succession of the ecosystems of the Aral Sea during its transition from oligohaline to polyhaline water body

During 22 field trips from 1990 to 2002 (mainly the western basin of the Large Aral) data on salinity, phytoplankton, zooplankton, zoobenthos and fish fauna have been collected. In 2002, the salinity of the western basin reached 75 ppt, while that in the eastern basin, 150 ppt. In 1999–2002, 159 species of planktonic algae have been recorded. This is approximately twice as low as recorded before. The diversity of Cyanophyta, Pyrrhophyta and Chlorophyta in particular has dropped in the past few years. As before, currently Bacillariophyta is the most diverse plankton. However, the composition of dominants has changed. Once previously dominant species, Actinocyclus ehrenbergii, vanished from the plankton of the Aral Sea and was replaced by such diatoms as Amphora coffeaformis, A. coffeaformis var. acutiuscula and Synedra tabulata var. parva.Since 1970s, a gradual decrease in the diversity of zooplankton has been taking place. Since 1997, the formerly dominant Calanipeda aquaedulcis vanished, which apparently was the reason for the emergence of Moina salina and Artemia parthenogenetica. Since 2000, artemia has been dominant in the plankton of the Aral Sea, constituting 99% of the zooplankton biomass.In the 1970–1980s, a rapid decrease in the biodiversity of the zoobenthos was observed. In the 1990s, most aboriginal and introduced species became extinct. Currently, the bivalve mollusk Syndosmya segmentum, the ostracod Cyprideis torosa and larvae of the dipteran Chironomus salinarius can still be recorded in the western basin. In the eastern basin no benthos is observed.By 1998, in the Large Aral, only five fish species survived: baltic herring Clupea harengus membras, flounder Platichthys flesus luscus, atherine Atherina boyeri caspia and bullheads Neogobius fluviatilis and Potamoschistus caucasicus. Since 2002, only flounder and atherina have been recorded in the western basin of the Large Aral. No fish have been recorded in the eastern part of the Aral Sea in 2002.With increasing salinity and transition of the Aral Sea from an oligohaline to a polyhaline water body, its biota is becoming drastically poorer. Almost all local species became extinct in the Aral; however, some still survive (including some endemics) in some lakes around the Aral Sea. In the near future, artemia will be the only animal in the Aral Sea.     

New technology and maritime training in the 21<Superscript>st</Superscript> century: Implications and solutions for MET institutions

This paper examines the impact of new technology on MET institutions in the 21^st 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.     

The UNCTAD and WORKPORT models of port development: evolution or revolution?

Around ten years have elapsed since the UNCTAD model on port development was put forward as an explanation of how ports have adapted to incorporate technological, political and operational changes. The UNCTAD Three Generation Port Model is critically examined in the light of research carried out under the WORKPORT project funded by the European Commission, 1998-1999. Evidence from the WORKPORT study shows that, rather than developing in discrete steps, ports evolve continuously, adapting to new technologies, fresh legislation, revised working practices and other influences on an as-required basis. Further, it is demonstrated that several streams of evolution can be observed simultaneously; the pace of change within each stream can vary substantially. One of the prominent features of ports is that they often have several terminals, some operating along traditional lines while others may be leading edge in terms of technology, working practices or other aspects; all of them may be equally effective. The UNCTAD model, implying ports develop in discrete steps, or generations, is therefore shown to be fundamentally flawed.