Traffic is a major source of ultrafine aerosol particles in urban environments. Recent studies show that a significant fraction of traffic-related particles are only few nanometers in diameter. Here, we study the dispersion of this nanocluster aerosol (NCA) in the size range 1.3–4 nm. We measured particle concentrations near a major highway in the Helsinki region of Finland, varying the distance from the highway. Additionally, modelling studies were performed to gain further information on how different transformation processes affect NCA dispersion. The roadside measurements showed that NCA concentrations fell more rapidly than the total particle concentrations, especially during the morning. However, a significant amount of NCA particles remained as the aerosol population evolved. Modelling studies showed that, while dilution is the main process acting on the total particle concentration, deposition also had a significant impact. Condensation and possibly enhanced deposition of NCA were the main plausible processes explaining why dispersion is faster for NCA than for total particle concentration, while the effect of coagulation on all size ranges was small. Based on our results, we conclude that NCA may play a significant role in urban environments, since, rather than being scavenged by larger particles, NCA particles remain in the particle population and grow by condensation.
Abstract-The aim of this paper is to introduce the measurement method for challenging Non-Line of Sight (NLOS) conditions in mobile networks. The need to develop the measurement method appeared LTE (Long Term Evolution) uplink (UL) performance with different antenna technologies when receiving NLOS signal in field tests. Many challenges appeared during the study. This paper introduces the challenges and presents solution.
Geographic information system (GIS) is traditionally used with desktop computers. The development of embedded, wireless, and positioning technologies have opened possibilities to apply GIS in new application areas and conditions. In this research area interoperability issues have been regognized to be one of the main challenges of in situ measurements in geosensor network (GSN) when using low-rate communication. We will present in this paper our first experiences about how to use geosensor network nodes and interoperable communication together with our location-aware system platform called Locawe. In the designed system GSN nodes are supporting IPv6 Packets over IEEE 802.15.4 (6LoWPAN) specification and are integrated with a GPS receiver. In addition in the designed system, GSN nodes can be used with mobile devices based on Open Geospatial Consortium (OGC) SensorML standard and Binary XML best practices specification. As a result interoperable communication was tested successfully with two different kinds of mobile devices. On the other hand results show that better compressions are still needed for more efficient communication in low-rate networks.
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