Influence of climatic variables on wireless: case study Base-Station Receiver

The development of this research is done with the aim of finding the relationship betweenweather conditions and the loss of wireless connection. The data were obtained by ameteorological center of the area and a telecommunications company that operates in the sameplace. We studied different models based on fuzzy logic due to the easy interpretation the easyinterpretation of the rules and data management. We used the Weka application that providestools for pre-processing of data and Keel software tool for data classification. Nine classifiersbased on fuzzy rules were applied, where the Furia-C was that better results obtained in orderto quality and quantity of rules. In this scenario, a preprocessing of data were computed, wheresome techniques to improve the information was performed. Some of the obtained rulerscorroborate the influence of heavy rain over the loss of the signal, but other relationships thatincorporate new knowledge in the area, such as dew point and the average relative humidityappear

Imaging of high-Z material for nuclear contraband detection with a minimal prototype of a Muon Tomography station based on GEM detectors

Muon Tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons in matter is a promising technique for detecting heavily shielded high-Z radioactive materials (U, Pu) in cargo or vehicles. The technique uses the deflection of cosmic ray muons in matter to perform tomographic imaging of high-Z material inside a probed volume. A Muon Tomography Station (MTS) requires position-sensitive detectors with high spatial resolution for optimal tracking of incoming and outgoing cosmic ray muons. Micro Pattern Gaseous Detector (MPGD) technologies such as Gas Electron Multiplier (GEM) detectors are excellent candidates for this application. We have built and operated a minimal MTS prototype based on 30cm \times 30cm GEM detectors for probing targets with various Z values inside the MTS volume. We report the first successful detection and imaging of medium-Z and high-Z targets of small volumes (~0.03 liters) using GEM-based Muon Tomography

Influence of climatic variables on wireless: case study Base-Station Receiver

The development of this research is done with the aim of finding the relationship betweenweather conditions and the loss of wireless connection. The data were obtained by ameteorological center of the area and a telecommunications company that operates in the sameplace. We studied different models based on fuzzy logic due to the easy interpretation the easyinterpretation of the rules and data management. We used the Weka application that providestools for pre-processing of data and Keel software tool for data classification. Nine classifiersbased on fuzzy rules were applied, where the Furia-C was that better results obtained in orderto quality and quantity of rules. In this scenario, a preprocessing of data were computed, wheresome techniques to improve the information was performed. Some of the obtained rulerscorroborate the influence of heavy rain over the loss of the signal, but other relationships thatincorporate new knowledge in the area, such as dew point and the average relative humidityappear

Spitzer observations of the Orion OB1 association: second generation dust disks at 5-10 Myr

We report new Spitzer observations of intermediate mass stars in two regions of the Orion OB1 association located in the subassociations OB1a ($\sim$10 Myr) and OB1b ($\sim$5 Myr). In a representative sample of stars earlier than F5 of both stellar groups, we find a population of stars surrounded of debris disks, without excess in the IRAC bands and without emission lines in their optical spectra, but with a varying degree of 24{\micron} excess. Comparing our samples with 24{\micron} observations of intermediate mass stars in other stellar groups, spanning a range of ages from 2.5 Myr to 150 Myr, we find that debris disks are more frequent and have larger 24{\micron} excess at 10 Myr (OB1a). This trend agrees with predictions of models of evolution of solids in the outer regions of disks ($>$30 AU), where large icy objects ($\sim$1000 Km) begin to form at $\sim$10 Myr; the presence of these objects in the disk initiates a collisional cascade, producing enough dust particles to explain the relatively large 24 {\micron} excess observed in OB1a. The dust luminosity observed in the stellar groups older than 10 Myr declines roughly as predicted by collisional cascade models. Combining Spitzer observations, optical spectra and 2MASS data, we found a new Herbig Ae/Be star (HD290543) and a star (HD36444) with a large 24 {\micron} excess, both in OB1b. This last object could be explained as a intermediate stage between HAeBe and true debris systems or as a massive debris disk produced by a collision between two large objects ($>$1000 Km).Comment: 25 pages, 8 figures, 2 tables. To be published in Astrophysical Journal (Acepted: 24 Jul 2006

Definición de retiros en cuencas urbanas.

Se propone en este trabajo una metodología para la definición de los retiros en cuencas urbanas altamente intervenidas, en función de elementos tales como: capacidad hidráulica del río, estabilidad de márgenes y taludes del cauce, franjas para zonas ornamentales y recreación pasiva, franjas de terreno para la extensión de redes de servicios públicos, zonas para la circulación, vías vehiculares o peatonales, zonas de amortiguación para la protección de los ecosistemas en los cauces y las riberas y acceso al cauce y a las zonas de amortiguación para su mantenimiento

Electrometeoros y aerosoles piroelectricos en tormentas tropicales

Los electrometeoros, como los rayos y los relámpagos, son manifestaciones del campo eléctrico atmosférico y de lapluviosidad. La microfísica asociada de los elecrometeoros parece estar asociada también a las propiedades físicas y químicas de la atmósfera local de ocurrencia. El metano es un aerosol asociado a la microfísica atmosférica. La concentración de metano en la troposfera superior podría favorecer la formación de núcleos polares donde el campo eléctrico se incrementa localmente en las nubes de tormentas. Se presenta un estudio microfísico de la influencia del metano como agente cocausal de los electrometeoros en la atmósfera baja. El modelo teórico elaborado muestra de que manera está vinculado el campo eléctrico local y los aerosoles piroelectricos, como el metano, con los procesos microfísicos de la convección y el transporte de cargas en nubes de tormentas. Se concluye que los cristales piroelectricos facilitan la génesis de electrometeoros en tormentas

Electrical self-polarization in intracloud lightning flashes

We present a theoretical microphysical model of thundercloud electrification that incorporates the influence of an aerosol with electrical self-polarization (pyroelectric) like methane. We estimate the water and methane dipole contribution to the internal electric field of a cloudy cell. Using a cloudy cell like a cube of 3.6 Km side, we obtain that the water contribution to the internal electric field, due to the electrical displacement vector generated by the atmospheric electric field of the Earth, is not enough to produce a typical discharge; the methane increases the electric field inside the thunderclouds and facilitates the electrical charge generation and separation process. We calculate the associated capacitance for the cloudy cell and the internal electric field. The results obtained for the charge of a cloudy cell due to a methane concentration (using a concentration lower than the air composition) and water, seem to agree with recent observations in lightnin

The methane influence as a self-polarized aerosol in Titan’s electrical activity

13th International Conference on Atmospheric Electricity, August 13-17, 2007, Beijing, ChinaMicrophysics that generates lightning flashes is associated with the physical chemistry properties of the local occurrence atmosphere. The principal agent of the electrical activity in Titan could be the methane because of its self-polarization properties or pyroelectricity. We calculate the charge obtained by Titan’s thunderclouds due to methane, using the approximations of thunderclouds as telluric capacitors. We present a time dependent mechanism because the life time of thunderclouds is very low; for that, we employ common atmospheric approach used for the Earth, because the similitude of both atmospheres in their chemical compositions. In Titan’s atmosphere the methane concentration is bigger than the Earth, and the electrical activity is superior, so the observed phenomenology seems to agree with this model