Free Space Optics Systems (FSO) is one of the most effective solutions, especially for atmospheric turbulence due to the weather and environment structure. Free space optics system suffers from various limitations. A well-known... more
Free Space Optics Systems (FSO) is one of the most effective solutions, especially for atmospheric turbulence due to the weather and environment structure. Free space optics system suffers from various limitations. A well-known disadvantage of FSO is its sensitivity on local weather conditions-primarily to haze and rain, resulting in substantial loss of optical signal power over the communication path. The main objective of this article is to evaluate the quality of data transmission using Wavelength Division Multiplexing (WDM) with highlighting several factors that will affect the quality of data transmission. The results of these analyses are to develop a system of quality-free space optics for a high data rate transmission. From the result analysis, FSO wavelength with 1550 nm produces less effect in atmospheric attenuation. Short link range between the transmitter and receiver can optimize the FSO system transmission parameters or components. Based on the analysis, it is recommended to develop an FSO system of 2.5 Gbps with 1550 nm wavelength and link range up to 150 km at the clear weather condition of bit-error-rate (BER) 10−9
In book: Adverse weather in Spain, edited by Ediciones Antonio Madrid Vicente, 08/2013. Chapter: Extreme rainfall rates and probable maximum precipitation, pages 135-148, ISBN: 978-84-96709-43-0. ABSTRACT: One of the most important... more
In book: Adverse weather in Spain, edited by Ediciones Antonio Madrid Vicente, 08/2013. Chapter: Extreme rainfall rates and probable maximum precipitation, pages 135-148, ISBN: 978-84-96709-43-0.
ABSTRACT: One of the most important climatic features that characterize a territory is its pluviometric regime and, in particular, the extreme rainfall rates produced in the area. Their knowledge is essential for planning hydraulic works and for designing rainwater drainage systems and flood prevention. In addition, the behavior of this variable can be very useful for the evaluation of possible effects of the climatic change. In this chapter we summarize the methodology used in the calculation of the frequencies associated to maximum precipitations expected in an area according to rainfall duration. Results about the probable maximum precipitation in 24 hours for the 145 pluviometric stations of Catalonia are also shown. The obtained spatial distribution shows rainfall amounts in the range 200-550 mm, in a good concordance with the annual average distribution but with some exceptions caused probably by the different meteorological scales involved in each case.
While rural freeways generally have lower crash rates, interactions between driver behavior, traffic and geometric characteristics, and adverse weather conditions may increase the crash risk along some freeway sections. This paper... more
While rural freeways generally have lower crash rates, interactions between driver behavior, traffic and geometric characteristics, and adverse weather conditions may increase the crash risk along some freeway sections. This paper examines the safety effects of roadway geometrics on crash occurrence along a freeway section that features mountainous terrain and adverse weather. Starting from preliminary exploration using Poisson models, Bayesian hierarchical models with spatial and random effects were developed to efficiently model the crash frequencies on road segments on the 20-mile freeway section of study. Crash data for 6 years (2000–2005), roadway geometry, traffic characteristics and weather information in addition to the effect of steep slopes and adverse weather of snow and dry seasons, were used in the investigation. Estimation of the model coefficients indicates that roadway geometry is significantly associated with crash risk; segments with steep downgrades were found to drastically increase the crash risk. Moreover, this crash risk could be significantly increased during snow season compared to dry season as a confounding effect between grades and pavement condition. Moreover, sites with higher degree of curvature, wider medians and an increase of the number of lanes appear to be associated with lower crash rate. Finally, a Bayesian ranking technique was implemented to rank the hazard levels of the roadway segments; the results confirmed that segments with steep downgrades are more crash prone along the study section.
This study examines the interaction between roadway geometric characteristics, adverse weather conditions on crash occurrence on rural Variable Speed Limit (VSL) freeway corridors through mountainous terrain. On Wyoming Interstate 80,... more
This study examines the interaction between roadway geometric characteristics, adverse weather conditions on crash occurrence on rural Variable Speed Limit (VSL) freeway corridors through mountainous terrain. On Wyoming Interstate 80, winter crashes are three times higher than summer crashes and adverse weather conditions are a contributing factor for more than 70 percent of the winter crashes. As a quantitative measure of the effect of geometrics in adverse weather conditions, a safety performance function was developed with explanatory variables including snow, ice, frost, wind, horizontal curvature and steep grades. The Generalized Linear Regression Model was used for finding the significance of the explanatory variables. This research concluded that the interaction between grades and horizontal curves with weather variables have a significant impact on crash occurrence. The results from the models suggest that distinct VSL strategies should be implemented on segments with challenging roadway geometry.
Free Space Optics Systems (FSO) is one of the most effective solutions, especially for atmospheric turbulence due to the weather and environment structure. Free space optics system suffers from various limitations. A well-known... more
Free Space Optics Systems (FSO) is one of the most effective solutions, especially for atmospheric turbulence due to the weather and environment structure. Free space optics system suffers from various limitations. A well-known disadvantage of FSO is its sensitivity on local weather conditions-primarily to haze and rain, resulting in substantial loss of optical signal power over the communication path. The main objective of this article is to evaluate the quality of data transmission using Wavelength Division Multiplexing (WDM) with highlighting several factors that will affect the quality of data transmission. The results of these analyses are to develop a system of quality-free space optics for a high data rate transmission. From the result analysis, FSO wavelength with 1550 nm produces less effect in atmospheric attenuation. Short link range between the transmitter and receiver can optimize the FSO system transmission parameters or components. Based on the analysis, it is recomme...
