Variability of river plumes off Northwest Iberia in response to wind events

The Western Iberian Buoyant Plume (WIBP) is a low-salinity lens formed by river discharge and continental run-off extending along the shelf off Northwest Iberia. The variability of this structure is evaluated with a numerical model forced by real meteorological data and climatologic river discharge during late 2002, when conditions were those of a typical autumn. The direction and intensity of the wind-induced Ekman transport, but also the previous conditions and the duration of the event are found to determine plume behavior. We have identified three characteristic situations: a) confinement of the plume to the coast during downwelling — southerly-winds, b) expansion of the plume during the declining phase of the downwelling event by relaxation of the wind, and c) expansion of the plume by upwelling — northerly-winds. The short time scale of the response of the plume (1–3 h) adds timing between wind events and the phase of the tide as an additional source of variability. In all cases the Iberian Poleward Current (IPC), a saltier and warmer poleward current flowing over the slope, responds as well to wind changes. Furthermore, our simulations illustrate how topography and differences in the river discharge induce local differences in dynamics. Comparisons to available observations show a reasonable model skill. Differences between wind measurements and wind forcing applied to the model appear to be a major source of uncertainty in model results.     

Forecast verification of a 3D model of the Mediterranean Sea. The use of discrete wavelet transforms and EOFs in the skill assessment of spatial forecasts

The quality assessment of a nested model system of the Mediterranean Sea is realised. The model has two zooms in the Provençal Basin and in the Ligurian Sea, realised with a two-way nesting approach. The experiment lasts for nine weeks, and at each week sea surface temperature (SST) and sea level anomaly are assimilated. The quality assessment of the surface temperature is done in a spatio-temporal approach, to take into account the high complexity of the SST distribution. We focus on the multi-scale nature of oceanic processes using two powerful tools for spatio-temporal analysis, wavelets and Empirical Orthogonal Functions (EOFs). We apply two-dimensional wavelets to decompose the high-resolution model and observed SST into different spatial scales. The Ligurian Sea model results are compared to observations at each of those spatial scales, with special attention on how the assimilation affects the model behaviour. We also use EOFs to assess the similarities between the Mediterranean Sea model and the observed SST. The results show that the assimilation mainly affects the model large-scale features, whereas the small scales show little or no improvement and sometimes, even a decrease in their skill. The multiresolution analysis reveals the connection between large- and small-scale errors, and how the choice of the maximum correlation length of the assimilation scheme affects the distribution of the model error among the different spatial scales.     

The viability of pure vegetable oil as an alternative fuel for large ships

Heavy fuels are likely to remain the dominant fuel source for two-stroke, low-speed diesel engines for large ship propulsion for the next decade or more. There is however, potential for increased use of pure vegetable oils (PVO) as an alternative and, by emitting lower levels of several pollutants, this can help the attainment of Annex VI of the MARPOL 73/78 convention aimed at large ships using fuels with less than 4.5% sulphur or 1.5% sulphur in SO_X emission control areas The use of alternative fuels can also influence the attainment of the Kyoto protocol that requires greenhouse gas emissions to be reduced by 5% by 2010 compared to 1990. This paper analyses the physical and chemical properties of various pure vegetable oils as an alternative to heavy fuel oil for large ship propulsion.     

日本轨道交通列车运行控制系统

在研究日本轨道交通信号系统发展历史的基础上.剖析了日本典型的四类轨道交通运行控制系统总体特征;并从电子技术、计算机技术和通信技术方面分析了日本轨道交通列车控制系统的原理、功能、结构和技术特点.研究了轨道交通列车刹车系统能有效防止列车正面冲撞的原理;分析了轨道交通列车自动保护系统具有列车自动保护的诸多功能;论证了轨道交通列车分布式自动控制系统的功能结构与技术特点.     

A study of the Alboran sea mesoscale system by means of empirical orthogonal function decomposition of satellite data

This paper presents the results of a combined empirical orthogonal function (EOF) analysis of Advanced Very High Resolution Radiometer (AVHRR) sea surface temperature (SST) data and sea-viewing wide field-of-view sensor (SeaWiFS) chlorophyll concentration data over the Alboran Sea (Western Mediterranean), covering a period of 1 year (November 1997–October 1998). The aim of this study is to go beyond the limited temporal extent of available in situ measurements by inferring the temporal and spatial variability of the Alboran Gyre system from long temporal series of satellite observations, in order to gain insight on the interactions between the circulation and the biological activity in the system. In this context, EOF decomposition permits concise and synoptic representation of the effects of physical and biological phenomena traced by SST and chlorophyll concentration. Thus, it is possible to focus the analysis on the most significant phenomena and to understand better the complex interactions between physics and biology at the mesoscale. The results of the EOF analysis of AVHRR-SST and SeaWiFS-chlorophyll concentration data are presented and discussed in detail. These improve and complement the knowledge acquired during the in situ observational campaigns of the MAST-III Observations and Modelling of Eddy scale Geostrophic and Ageostrophic motion (OMEGA) Project.     

煤的气化——清洁选择 煤合成气——天然气的竞争者，清洁、廉价的电厂燃料

作为燃料有几个优势，其中包括储量充足和价格低廉。但是没有“清洁煤”这种说法。除了煤烟、有毒化学品，以及金属外，燃煤电厂每千瓦小时放出的二氧化碳也比燃烧石油或天然气的电厂要多。煤在空气中燃烧时不可避免地产生二氧化碳。因此煤是一种问题燃料，不仅在于它引发气候变化，而且影响到人类健康和安全问题。     

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.     

新型三点式软开关变流器

介绍了一种三点式恒频独立变流器,它使用一个耦合电感器来实现整个系统和负载范围内主开关的零电压开关.因为耦合电感器在负载电流回路中并不作为一个串联电感出现,所以它在输出整流管上并不造成负载循环损耗.在1 kW样机上验证了推荐的变流器工作情况和性能.     

Normal and risky driving patterns identification in clear and rainy weather on freeway segments using vehicle kinematics trajectories and time series cluster analysis

Enhancing traffic safety on freeways is the main goal for all transportation agencies. However, to achieve this goal, many analysis protocols of network screening models need to be improved through considering human factors while analyzing traffic data. This paper introduces one on the new analysis protocol of identifying and discriminating between normal and risky driving in clear and rainy weather. The introduced analysis protocol will consider the effect of human factors on updating the networking screening process of identifying hotspots of crash risk. This paper employs the Second Strategic Highway Research Program (SHRP2) Naturalistic Driving Study (NDS) data to investigate the behavior of normal and risky driving under both rainy and clear weather conditions. Near-crash events on freeways, which were used as Surrogate Measure of Safety (SMoS) for crash risk, were identified based on the changes in vehicle kinematics, including speed, longitudinal and lateral acceleration and deceleration rates, and yaw rates. Through a trajectory-level data analysis, there were significant differences in driving patterns between rainy and clear weather conditions; factors that affected crash risk mainly included driver reaction and response time, their evasive maneuvers such as changes in acceleration rates and yaw rates, and lane-changing maneuvers. A cluster analysis method was employed to classify driving patterns into two clusters: normal and risky driving condition patterns, respectively. Statistical results showed that risky driving patterns started on average one second earlier in rainy weather conditions than in clear weather conditions. Furthermore, risky driving patterns extended in average three seconds in rainy weather conditions, while it was two seconds in clear weather conditions. The identification of these patterns is considered as a primary step towards an automated development that would distinguish between different driving patterns in a Connected Vehicle CV environment using Basic Safety Messages (BSM) and to enhance the network screening analysis for increased crash risk hotspots.