Search results for "road"
showing 10 items of 851 documents
A Two-Dimensional Autoregressive Model for MIMO Wideband Mobile Radio Channels
2008
In this work, we propose the multichannel two- dimensional (2D) autoregressive (AR) model for multiple-input multiple-output (MIMO) wideband mobile wireless channels. The parameters of the proposed model can be estimated from the real- world measurement data. For this purpose, we suggest using a straightforward extension of the prediction error minimization (PEM) algorithm. We also address the problem of possible instability of the multichannel 2D AR model. A model stabilization procedure based on numerical optimization techniques is proposed. The performance of the multichannel 2D AR model has been evaluated based on the synthetic data generated using two different channel simulators.
Ko atklāj Ķīnas Ceļa un jostas iniciatīvas investīcijas? Nestriktas kopas kvalitatīvā salīdzinošā analīze
2020
Maģistra darbā “Ko atklāj Ķīnas Ceļa un jostas iniciatīvas investīcijas? Nestriktas kopas kvalitatīvā salīdzinošā analīze” tika analizēts Ķīnas Ceļa un jostas iniciatīvas (BRI) investīciju daudzums 78. Eirāzijas valstīs, lai noteiktu, kādi valstis raksturojoši faktori vai apstākļi ietekmē to vēlmi pievienoties BRI. Izvēlētajām valstīm pēc detalizētas pētnieciskās literatūras analīzes tika noteikti astoņi investīcijas veicinošie faktori (gan politiskie, gan ekonomiskie). Izvēlētie faktori tika pretnostatīti Ķīnas BRI investīciju apjomam uz vienu iedzīvotāju konkrētā valstī, lai varētu secināt, kādi valsti raksturojoši apstākļi un priekšnoteikumi veicina Ķīnas BRI investīciju plūsmu uz konkrē…
Construction of Disjoint Virtual Backbones for Wireless Sensor Networks
2020
A wireless sensor network is a wireless network of sensors aimed at monitoring physical events. It has ingratiated itself into almost all areas of human endeavors. Data dissemination in these networks is quite challenging and is generally accomplished by flooding. But flooding introduces broadcast storm problem due from implosion and overlap. To overcome this, topology management can prescribe a virtual backbone network to which routing is confined. In this paper we propose an algorithm that constructs multiple disjoint virtual backbone networks, using only nodes' locations. The disjointedness makes routing more robust and the network exploitation energy efficient. Simulations show our algo…
RoadMic: Road Surface Monitoring Using Vehicular Sensor Networks with Microphones
2010
Road surface analysis including pothole reports is an important problem for road maintainers and drivers. In this paper we propose a methodology for pothole detection using mobile vehicles equipped with off the shelf microphone and global positioning devices attached to an on-board computer. The approach is generic enough to be extended for other kind of event detection using different sensors as well. The vehicles are driving on public streets and measuring pothole induced sound signals. Our approach was tested and evaluated by real world experiments in a road segment for which we had established the ground truth beforehand. The results show pothole detection with high accuracy despite the…
Automated agent-based system for weather information
2009
Road accidents are well correlated with bad weather conditions. In traffic management, several strategies have been considered in order to reduce this kind of accidents. Weather problems can cause difficult situations for the traffic management decision-makers. They need to analyze and absorb a large quantity of information in order to solve some problems due to bad weather. An automated agent-based system is a good solution to help decision-makers in the management of weather information to road users in relation to traffic conditions.In this paper, a distributed system based in autonomous agents and rules for road weather information has been proposed. Also the detection procedure is expl…
Effect of temperature and traffic on mix-design of bituminous asphalt for railway sub-ballast layer
2017
A wide integrated research has been carried out to assess the suitability of bituminous mixtures as the sub-ballast layer in railways. The influence of temperature on the mechanical characteristics and thermal susceptibility of the bituminous conglomerate—which forms sub-ballast layer of railway lines—has provided the motivation for carrying out a measurement of the thermal cycles in this layer. The evaluation of the average seasonal temperatures has proven to be well interpolated by sinusoidal functions, of which characteristic parameters are determined. To expand the validity of the study in different weather situations apart from Sicily, where the experiment was held, we proceeded to app…
Latvijas Vēstures Institūta Žurnāls. 2014, Nr. 2 (91)
2014
Valsts kultūrkapitāla fonds
Optimal Relays Deployment for 802.16j Networks
2012
In this paper, we consider optimal relay station deployment for the IEEE 802.16j networks. IEEE 802.16j is an emerging wireless broadband networking standard that integrates infrastructure base stations with multihop relay technology. The proposed relay deployment mechanism allows us to maximize network capacity for every user or to maximize total network capacity, and, therefore, to reach greater network capacity values while employing smaller number of relay stations. With the proposed approach, the necessary number of relays for a region can be found.
Enable concurrent transmissions with beamforming for broadband wireless access in CSMA/CA-based WLANs
2014
In CSMA/CA based wireless local networks, two stations are not allowed to transmit at the same time due to interference generated to each other, resulting in degraded throughput. Concurrent transmission, which enables simultaneous transmission of two or more stations under certain conditions, is able to overcome this problem, leading to enhanced channel utilization efficiency. Different from earlier work on this topic which focuses on omni-direction concurrent transmission, we introduce in this paper beamforming into a co-channel concurrent transmission scheme and investigate the benefits of concurrency with beamforming. The circumstances for concurrent transmission and frame scheduling are…
Smart transportation as a driver of transition: Big data management, behavioral change and the shift to automated vehicles
2017
Background: Smart mobility can contribute to the design of “Smart cities” to answer users’ requests in terms of transport network efficiency, environmental and social sustainability. Focusing on urban smart mobility issues, the most important aspects are the presence of a connected transportation system, the availability of its information in the arrangement of digital data and the possibility to rapidly communicate it in an effective way to the citizens, urban transportation stakeholders andlocal authorities. Therefore, the challenges for the new era of mobility behavior would range from the effort of big data management and the need to shape the innovation of traveler demand to the change…