arXiv subjects

J. Velasco

Publications and source records attributed to J. Velasco.

10 recordsLinked to original sources

arXiv2019

Automated Smart Wick System-Based Microfarm Using Internet of Things

This paper presents a study conducted to allow urban farmers to remotely monitor their farm through the design and development of an Internet of Things-based (IoT) microfarm prototype which utilized wick system as planting method. The system involves the detection of three environmental parameters namely, light intensity, soil moisture and temperature through the use of respective sensors which were connected to the Arduino microcontroller, the sensor node of the system. Irregularities in the aforementioned parameters were neutralized through the use of parameter regulators such as LED growlight strips, water pump and air cooler. The data collected by these sensors were gathered by the Arduino microcontroller and were sent to the Web database through the IoT gateway which was the Raspberry Pi computer chip. These data were also sent to an Android unit installed with the Microfarm Companion application which was capable of monitoring and controlling the environmental parameters observed in the microfarm. The application allows the user to view the current value of the parameter involved and to choose whether to control the parameter regulators automatically or manually. The microfarm system runs autonomously which reduces the labor required to produce healthy plants and crops. Mustard greens samples were used in testing the system. After a month of monitoring the height of the samples, it was observed that the average height of the samples is about 0.23 cm taller than the standard height. The proponents has also tested the system functionality by evaluating the sensor data log that provides the values gathered by the sensors and the turn-on times of the parameter regulators. From these data, it can be observed that whenever the values obtained by the sensors fall outside the threshold range, the parameter regulators turns on, indicating that the system is working properly.

cs.CY↗

arXiv2013

Fixed points for nilpotent actions on the plane and the Cartwright-Littlewood theorem

The goal of this paper is proving the existence and then localizing global fixed points for nilpotent groups generated by homeomorphisms of the plane satisfying a certain Lipschitz condition. The condition is inspired in a classical result of Bonatti for commuting diffeomorphisms of the 2-sphere and in particular it is satisfied by diffeomorphisms, not necessarily of class $C^{1}$, whose linear part at every point is uniformly close to the identity. In this same setting we prove a version of the Cartwright-Littlewood theorem, obtaining fixed points in any continuum preserved by a nilpotent action.

math.DS↗

arXiv2011

Measurement of zero degree single photon energy spectra for sqrt(s) = 7TeV proton-proton collisions at LHC

In early 2010, the Large Hadron Collider forward (LHCf) experiment measured very forward neutral particle spectra in LHC proton-proton collisions. From a limited data set taken under the best beam conditions (low beam-gas background and low occurance of pile-up events), the single photon spectra at sqrt(s)=7TeV and pseudo-rapidity (eta) ranges from 8.81 to 8.99 and from 10.94 to infinity were obtained for the first time and are reported in this paper. The spectra from two independent LHCf detectors are consistent with one another and serve as a cross check of the data. The photon spectra are also compared with the predictions of several hadron interaction models that are used extensively for modeling ultra high energy cosmic ray showers. Despite conservative estimates for the systematic errors, none of the models agree perfectly with the measurements. A notable difference is found between the data and the DPMJET 3.04 and PYTHIA 8.145 hadron interaction models above 2TeV where the models predict higher photon yield than the data. The QGSJET II-03 model predicts overall lower photon yield than the data, especially above 2TeV in the rapidity range 8.81<eta<8.99.

hep-ex↗

arXiv2010

Early results of the LHCf Experiment and their contribution to Ultra-High-Energy Cosmic Ray Physics

LHCf is an experiment dedicated to the measurement of neutral particles emitted in the very forward region of LHC collisions. The physics goal is to provide data for calibrating hadron interaction models that are used in the study of Extremely High-Energy Cosmic-Rays. The LHCf experiment acquired data from April to July 2010 during commissioning time of LHC operations at low luminosity. Production spectra of photons and neutrons emitted in the very forward region ($η>$ 8.4) have been obtained. In this paper preliminary results of the photon spectra taken at $\sqrt{s}$ = 7TeV are reported.

hep-ex↗

arXiv2009

Evidence for Strain-Induced Local Conductance Modulations in Single-Layer Graphene on SiO2

Graphene has emerged as an electronic material that is promising for device applications and for studying two-dimensional electron gases with relativistic dispersion near two Dirac points. Nonetheless, deviations from Dirac-like spectroscopy have been widely reported with varying interpretations. Here we show evidence for strain-induced spatial modulations in the local conductance of single-layer graphene on SiO2 substrates from scanning tunneling microscopic (STM) studies. We find that strained graphene exhibits parabolic, U-shaped conductance vs. bias voltage spectra rather than the V-shaped spectra expected for Dirac fermions, whereas V-shaped spectra are recovered in regions of relaxed graphene. Strain maps derived from the STM studies further reveal direct correlation with the local tunneling conductance. These results are attributed to a strain-induced frequency increase in the out-of-plane phonon mode that mediates the low-energy inelastic charge tunneling into graphene.

cond-mat.mtrl-sci↗

arXiv2004

P-P Total Cross Sections at VHE from Accelerator Data

Comparison of P-P total cross-sections estimations at very high energies - from accelerators and cosmic rays - shows a disagreement amounting to more than 10 %, a discrepancy which is beyond statistical errors. Here we use a phenomenological model based on the Multiple-Diffraction approach to successfully describe data at accelerator energies. The predictions of the model are compared with data On the basis of regression analysis we determine confident error bands, analyzing the sensitivity of our predictions to the employed data for extrapolation. : using data at 546 and 1.8 TeV, our extrapolations for p-p total cross-sections are only compatible with the Akeno cosmic ray data, predicting a slower rise with energy than other cosmic ray results and other extrapolation methods. We discuss our results within the context of constraints in the light of future accelerator and cosmic ray experimental results.

hep-ph↗

arXiv2001

Precise measurement of the total cross section and the Coulomb scattering at the LHC

A precise measurement of the total cross section and the coulomb scattering at the LHC requires the observation of elastically scatteredparticles at extremely small angles (14 microrad, -t < 0.01 GeV**2 for the first case; 3 microrad, -t<0.0006 GeV**2 for the second one). In this paper a very high-beta insertion optics is presented. A feasibility study, including the acceptance of the detectors, for an experiment to be installed in IR1 or IR5, is also presented.

hep-ex↗

arXiv2000

Parametrization of proton-proton total cross section from 10 GeV to 100 TeV

Present estimations of proton-proton total cross section at very high energies are obtained from cosmic rays (>10^17 eV) by means of some approximations and the knowledge of the measured proton-air cross section at these energies. Besides, total cross section are measured with present day high energy colliders up to nearly 2 TeV in the center of mass (~ 10^15 eV in the laboratory). Here we use a phenomenological model based on the Multiple-Diffraction approach to succesfully describe data at accelerator energies. Then we estimate with it proton-proton total cross sections at cosmic ray energies. On the basis of a forecasting regression analysis we determine confident errors bands, analyzing the sensitivity of our predictions to the employed data for extrapolation.

hep-ph↗

arXiv1999

Proton-proton total cross sections estimations at very high energies

Proton-proton total cross sections are measured with present day high energy colliders up to 2 TeV in the centre-of-mass of the system (10^{15}) eV in the laboratory). Several parameterizations, very succesful at low energies, can then be used to extrapolate the measured values and get estimations of cross sections to higher energies (10^{17} eV). On the other hand, from very high energetic cosmic rays (> 10^{17} eV) and using some approximations, it is possible to get a value for proton-proton total cross section from the knowledge of the proton-proton total cross section at these energies. Here we use a phenomenological model to estimate proton-proton total cross section at cosmic ray energies. On the basis of regression analysis we show that the predictions are highly sensitive to the employed data for extrapolation. Using data at 1.8 TeV our extrapolations for proton-proton total cross section are incompatible with most of cosmic ray results

hep-ph↗

arXiv1996

A comparative study on two characteristic parametrizations for high energy pp and pp total cross sections

Available high energy data for both pp and pp total cross sections ($ 5 \ GeV \ < \ \sqrt s \ < \ 1.8 \ TeV$) are described by means of two well-known distinct parametrizations, characteristic of theoretical (``Regge-like" expression) and experimental (``Froissart-Martin-like" expression) practices, respectively. Both are compared from the statistical point of view. For the whole set of present data, statistical analysis ($χ^2/d.o.f.$) seems to favour a ``Froissart-like" ((ln $s$)$^{γ\approx 2}$ ) rise of the total cross section rather than a ``Regge-like" ($s^ε$) one.

hep-ph↗