Abstract

Abstract. Radiation fog occurs over many locations around the world in stable atmospheric conditions. Air traffic at busy airports can be significantly disrupted because low visibility at the ground makes it unsafe to take off, land and taxi on the ground. Current numerical weather prediction forecasts are able to predict general conditions favorable for fog formation, but not the exact time or location of fog occurrence. A selected set of observations available in near-real time at strategic locations could also be useful to track the evolution of key processes and key parameters that drive fog formation. Such observations could complement the information predicted by numerical weather prediction (NWP) models that is made available to airport forecasters in support of their fog forecast. This paper presents an experimental setup based on collocated automatic lidar and ceilometer measurements, relative humidity measurements and horizontal visibility measurements to study hygroscopic growth of fog condensation nuclei. This process can take several minutes to hours, and can be tracked using lidar- or ceilometer-attenuated backscatter profiles. Based on hygroscopic growth laws we derive a set of parameters that can be used to provide alerts minutes to hours prior to formation of radiation fog. We present an algorithm that uses the temporal evolution of attenuated backscatter measurements to derive pre-fog formation alerts. The performance of the algorithm is tested on 45 independent pre-fog situations at two locations (near Paris, France, and Brussels, Belgium). We find that an alert for pre-fog conditions predominantly occurs 10–50 min prior to fog formation at an altitude ranging 0 to 100 m above ground. In a few cases, alerts can occur up to 100 min prior to fog formation. Alert durations are found to be sensitive to the relative humidity conditions found a few hours prior to the fog. Document type: Article

Abstract

RESUMO: O sistema de transporte coletivo da cidade de Curitiba, no Paraná, é reconhecido pelas suas soluções inovadoras e modelo para o Brasil. Neste trabalho foi analisada a influência do combustível (diesel e biodiesel) e das condições da frota de veículos do transporte coletivo de Curitiba nas emissões de NOx, e essa é uma iniciativa pioneira. Foram selecionados 188 veículos (9,7% do total) com motores de 7 a 12 L, denominados B7R, B10M, B12M e B215RH, e foram realizadas medições de NO e NO2 na saída dos escapamentos. Com relação ao tipo de combustível, as emissões de NO e NO2 para o biodiesel (B100) foram, respectivamente, 37 e 26% superiores aos valores observados com o combustível diesel (S10). Comparando motores B12M com até 3 e 10 anos de operação, as emissões médias de NOx foram próximas de 40% maior. Assim, foi possível observar que os veículos a biodiesel tiveram maior emissão de NOx quando comparados com veículos a diesel, em condições similares de operação e tempo de uso do motor. Entretanto, embora o uso de biodiesel traga vantagens ambientais, como energia renovável, novas tecnologias e dispositivos devem ser desenvolvidos para controlar emissões de NO e NO2 em motores que utilizam esse tipo de combustível. Para trabalhos futuros, os autores recomendam testes em dinamômetro, para simular emissões de NOx em motores a diesel e biodiesel em diferentes condições de carga e regime de rotação do motor. ABSTRACT: The public transportation system in Curitiba, Paraná, Brazil, is recognized by its innovative solutions; and is a model for Brazil. In this work, the influence of fuel (diesel and biodiesel) and the conditions of the public transport vehicle fleet of Curitiba in NOx emissions was assessed, and this is a pioneered initiative. A total of 188 vehicles (9.7% of the total) with engines of 7 and 12 L were selected, named B7R, B10M, B12M and B215RH, and measurements of NO and NO2 were performed in the exhaust output. In relation to the type of fuel, the emissions of NO and NO2 for biodiesel (B100) were, respectively, 37 and 26% superior to the values observed with the fuel diesel (S10). Comparing the engines B12M with up to 3 and 10 years of operation, the average emissions of NOx were close to 40% higher. Thus, it was possible to observe that the biodiesel vehicles had higher NOx emissions when compared with diesel vehicles in similar conditions of operation and engine wear time. Therefore, although the use of biodiesel brings environmental advantages, as renewable fuel, new technologies and devices must be developed to control emissions of NO and NO2 in engines that use this type of fuel. For future works the authors recommend tests on dynamometer to simulate NOx emission in diesel and biodiesel engine in different conditions of charge and engine speed. Document type: Article

Abstract

The goal of the study presented in this article is to provide a general overview of the various aspects related to electric vehicles (EVs), along with all associated emerging challenges and perspectives. In this context, the basic types of EVs and the corresponding charging technologies are analyzed. Since EVs are expected to be a key component of future smart electrical grids (SEG), connection to the grid issues, along with advanced charging techniques (i.e., wireless power transfer), are analyzed as well. To this end, the main features, the requirements of vehicle to grid (V2G) communications, as well as future developments and scenarios of electrification, are also presented and analyzed. Moreover, integration issues with currently deployed fifth generation (5G) mobile wireless networks are also outlined, in order to ensure optimum transmission and reception quality in V2G communications and improved user experience. This integration is also expanded in autonomous vehicles (AVs) technology (self-driving objects), since optimized information processing from various diverse sources is required in order to ensure advanced traffic management aspects. Document type: Article