1,111 research outputs found
Sistema de monitoreo multivariable para electrolizadores alcalinos de baja escala
No full textEn este estudio se enfatiza la relevancia de la transición hacia energías renovables mediante la implementación de electrolizadores alcalinos (AWEs) para la producción de hidrógeno verde. Los AWEs, desde su introducción en el siglo XVIII, han evolucionado desde capacidades iniciales de 0.08 Nm³/h hasta alcanzar 1.200 Nm³/h en configuraciones industriales modernas. Este trabajo introduce un sistema de monitoreo multivariable y modular (EMM) diseñado para AWEs de baja escala (hasta 2.5 kW), que incorpora una interfaz gráfica de usuario para facilitar una operación eficiente y segura. El EMM monitoriza en tiempo real las variables críticas incluyendo temperatura (T), presión (P), flujo de hidrógeno (Fh), voltaje (Vy), y corriente (C), lo que permite adaptaciones dinámicas a las condiciones operativas. Durante las pruebas, el sistema demostró un incremento del 250 % en la producción de hidrógeno al ajustar la temperatura en un 60 % y la presión en un 10 %. El diseño compacto del EMM, con dimensiones de 14 cm x 5 cm x 15 cm y un peso de 2 kg, junto con su capacidad de operar autónomamente por 18 horas, subrayan su aplicabilidad en diversos entornos operativos. Estos resultados destacan la importancia de sistemas de monitoreo integrados y adaptativos en la optimización de la producción de hidrógeno y la integración de AWEs con las redes de energía renovable.This study emphasizes the importance of transitioning to renewable energies through the deployment of alkaline water electrolyzers (AWEs) for green hydrogen production. AWEs, since their introduction in the 18th century, have evolved from initial capacities of 0.08 Nm³/h to modern industrial configurations reaching up to 1,200 Nm³/h. This work introduces a multivariable and modular monitoring system (EMM) designed for low-scale AWEs (up to 2.5 kW), incorporating a graphical user interface to facilitate efficient and safe operation. The EMM monitors critical variables in real-time including temperature (T), pressure (P), hydrogen flow (Fh), voltage (Vy), and current (C), allowing dynamic adaptations to operational conditions. During testing, the system demonstrated a 250 % increase in hydrogen production by adjusting the temperature by 60 % and the pressure by 10 %. The compact design of the EMM, with dimensions of 14 cm x 5 cm x 15 cm and a weight of 2 kg, along with its capability to operate autonomously for 18 hours, underscore its applicability in various operational environments. These results highlight the importance of integrated and adaptive monitoring systems in optimizing hydrogen production and integrating AWEs with renewable energy networks.Pregrad
Particle production in 158.A GeV Pb + Pb collisions
No full textThe production of neutral pions in 158.A GeV /sup 208/Pb+/sup 208/Pb collisions has been studied in the WA98 experiment. The centrality dependence of the neutral pion production is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with more than about 50 participants. The transverse mass spectrum is analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement constrains the extracted freeze-out parameters, and provides information on the freeze-out velocity profile. (18 refs)
Spectra and ratios of identified particles in Au plus Au and d plus Au collisions at root s(NN)=200 GeV
No full textThe transverse momentum (p(T)) spectra and ratios of identified charged hadrons (pi(+/-), K-+/-, p, (p) over bar) produced in root s(NN) = 200 GeV Au + Au and d + Au collisions are reported in five different centrality classes for each collision species. The measurements of pions and protons are reported up to p(T) = 6 GeV/c (5 GeV/c), and the measurements of kaons are reported up to p(T) = 4 GeV/c (3.5 GeV/c) in Au + Au (d + Au) collisions. In the intermediate p(T) region, between 2 and 5 GeV/c, a significant enhancement of baryon-to-meson ratios compared to those measured in p + p collisions is observed. This enhancement is present in both Au + Au and d + Au collisions and increases as the collisions become more central. We compare a class of peripheral Au + Au collisions with a class of central d + Au collisions which have a comparable number of participating nucleons and binary nucleon-nucleon collisions. The p(T)-dependent particle ratios for these classes display a remarkable similarity, which is then discussed.Physics, NuclearSCI(E)0ARTICLE2null8
Azimuthal anisotropy of pi(0) and eta mesons in Au plus Au collisions at root s(NN)=200 GeV
No full textThe azimuthal anisotropy coefficients v2 and v4 of p 0 and. mesons are measured in Au + Au collisions at root s(NN) = 200 GeV as a function of transverse momentum p(T) (1-14 GeV/c) and centrality. The extracted v(2) coefficients are found to be consistent between the two meson species over the measured p(T) range. The ratio of v(4)/v(2)(2) for pi(0) mesons is found to be independent of p(T) for 1- 9 GeV/c, implying a lack of sensitivity of the ratio to the change of underlying physics with p(T). Furthermore, the ratio of v(4)/v(2)(2) is systematically larger in central collisions, which may reflect the combined effects of fluctuations in the initial collision geometry and finite viscosity in the evolving medium.Physics, NuclearSCI(E)0ARTICLE6null8
Wave Limitations for Floating AWES: A method for determining effects of wave induced motions on horizontally landing Airborne Wind Energy Systems on floating foundations
No full textAirborne Wind Energy (AWE) is a field of engineering that utilizes tethered aircraft for the generation of electrical power. The potential for the application of AWE in deep-water offshore environments on top of floating foundations is enormous. Where conventional wind turbines would require a very stable platform to reduce motions at the nacelle, AWE requires just enough stability to survive extreme conditions, take-off and land horizontally, and not negatively affect cross-wind performance. The requirements scale well with increasing capacity of AWE systems, which mostly influences the mooring configuration instead of the steel structure. That is why Ampyx Power started an investigative study into the floating offshore application of AWE in collaboration with Mocean Offshore, MARIN and ECN.A driving factor in the design of the floating foundations is the maximum allowed motions in different sea states. The objective of this research is to determine the relative magnitude of the effect of platform motions on the landing performance. This will result in more clearly defined design requirements for both the floating platform and the aircraft. The method used in this research can be extended to more advanced numerical models at a later stage of the design to obtain quantified motion constraints or operational limits. It is assumed that standard deviations of several parameters at the end of the landing approach serve as good indicators of successful landings. A numerical model of a tethered aircraft (RPA) making a horizontal landing in time domain is developed to determine these parameters in a multitude of wind conditions. By performing a Monte-Carlo analysis, the standard deviations of these parameters can be acquired. Especially symmetric motions (X, Z and RY) are expected to affect landing performance, which is why a 3DOF model is used. Then harmonic platform motions are included in the model in order to investigate what type of platform motions are most critical. Finally, the platform designed by Mocean Offshore is examined. By combining the motion response of this platform with metocean data at a reference location, the standard deviation of critical parameters is obtained in comparison to an onshore application. The motion response of the platform is determined using a numerical model that combines potential theory with semi-empirical drag formulations. This model is validated with basin tests at MARIN.Simulations with harmonic platform motions indicate that both frequency and amplitude of platform motions are critical for the landing performance. The landing performance appear to be mainly related to the platform motion velocities. Therefore, increasing damping and added mass of the platform will both have a positive effect on the landing of the RPA.When looking further at the results of the simulations with platform motions based on metocean data and the hydrodynamic, numerical model, it was found that the current design of the floating platform by Mocean Offshore leads to an expected decrease in landing performance compared to the onshore application. The performance decrease is not insurmountable, and multiple methods of reducing the negative effects on landing performance are presented.Marine Technolog
K*(892)(0) and phi(1020) production in Pb-Pb collisions at root s(NN)=2.76 TeV
No full textThe yields of the K*(892)(0) and phi(1020) resonances are measured in Pb-Pb collisions at root s(NN) = 2.76 TeV through their hadronic decays using the ALICE detector. The measurements are performed in multiple centrality intervals at mid-rapidity (vertical bar y vertical bar < 0.5) in the transverse-momentum ranges 0.3 < p(T) < 5 GeV/c for the K*(892)(0) and 0.5 < p(T) < 5 GeV/c for the phi(1020). The yields of K*(892)(0) are suppressed in central Pb-Pb collisions with respect to pp and peripheral Pb-Pb collisions (perhaps due to rescattering of its decay products in the hadronic medium), while the longer-lived phi(1020) meson is not suppressed. These particles are also used as probes to study the mechanisms of particle production. The shape of the pT distribution of the phi(1020) meson, but not its yield, is reproduced fairly well by hydrodynamic models for central Pb-Pb collisions. In central Pb-Pb collisions at low and intermediate p(T), the p/phi(1020) ratio is flat in p(T), while the p/pi and phi(1020)/pi ratios show a pronounced increase and have similar shapes to each other. These results indicate that the shapes of the p(T) distributions of these particles in central Pb-Pb collisions are determined predominantly by the particle masses and radial flow. Finally, phi(1020) production in Pb-Pb collisions is enhanced, with respect to the yield in pp collisions and the yield of charged pions, by an amount similar to the Lambda and Xi
Direct photon production in d+Au collisions at root s(NN)=200 GeV
No full textDirect photons have been measured in root s(NN) = 200 GeV d + Au collisions at midrapidity. A wide p(T) range is covered by measurements of nearly real virtual photons (1 < p(T) < 6 GeV/c) and real photons (5 < p(T) < 16 GeV/c). The invariant yield of the direct photons in d + Au collisions over the scaled p + p cross section is consistent with unity. Theoretical calculations assuming standard cold-nuclear-matter effects describe the data well for the entire p(T) range. This indicates that the large enhancement of direct photons observed in Au + Au collisions for 1.0 < p(T) < 2.5 GeV/c is attributable to a source other than the initial-state nuclear effects.AuthorOverflow(546
System-size dependence of open-heavy-flavor production in nucleus-nucleus collisions at root s(NN)=200 GeV
No full textThe PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open-heavy-flavor production in Cu + Cu collisions at v root s(NN) = 200 GeV through the measurement of electrons at midrapidity that originate from semileptonic decays of charm and bottom hadrons. In peripheral Cu + Cu collisions an enhanced production of electrons is observed relative to p + p collisions scaled by the number of binary collisions. In the transverse momentum range from 1 to 5 GeV/c the nuclear modification factor is R-AA similar to 1.4. As the system size increases to more central Cu + Cu collisions, the enhancement gradually disappears and turns into a suppression. For p(T) > 3 GeV/c, the suppression reaches R-AA similar to 0.8 in the most central collisions. The p(T) and centrality dependence of R-AA in Cu + Cu collisions agree quantitatively with R-AA in d + Au and Au + Au collisions, if compared at a similar number of participating nucleons < N-part >.Physics, NuclearSCI(E)[email protected]; [email protected]
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