Search results for " PUM"
showing 10 items of 412 documents
A Hybrid Power Supply with Variable Speed Drive for Automatically Move Irrigation Equipment: Margin of Feasibility
2021
Center pivot irrigation systems are widely used in agriculture. Their water pumping systems are primary energy consumers. The use of photovoltaic power plants and variable speed drives of electric motors can reduce energy costs. The purpose of this study is to determine the feasibility of integrating variable speed drives and photovoltaic modules into water pumping systems. A novel architecture of a pumping system was suggested. Its features are no battery backup and the sale of electricity into the grid.
Performance analysis of photovoltaic powered dc motor — Propeller system
2015
The application of autonomous directly photovoltaic (PV) powered electro-mechanical has received increasing attention for different applications (e.g. PV water pumping, PV powered cooling of arid climate greenhouses, solar vehicles etc). The PV array output is a nonlinear and time-dependent power supply that varies with solar intensity and cell temperature, so the performance characteristics of the directly PV-powered DC motor — propeller system are very different than when powered by a constant DC voltage. The focus of this work is to do performance analysis of directly PV-powered DC motor — propeller system. Through performance evaluation, it has been observed that power transfer matching…
Design, modeling, and simulation of a photovoltaic water pumping system
2018
Electric pumps cannot be fed in those areas where they are not connected to the electric public distribution grid. In those areas, it is useful to feed electric pumps by means of the electricity generated from renewable energy sources plants. Among these, the Solar Water Pumping Systems feed electric pump thanks to the electricity generated by a photovoltaic plant. In this paper, a whole SWPS is fully designed, modelled, and simulated in Matlab environment. The proposed implementation is an useful tool for SWPS testing.
Modelling of Laser Operation in RPE Nd3+:LiNbO3 Channel Waveguides
2006
In this work, laser action in RPE Nd3+:LiNbO3 is modelled by using the overlapping integrals method. Different pumping schemes, TE or TM, have been considered in order to reproduce the experimental measurements. Calculated results indicate that the slope efficiency remains basically independent on the pumping scheme while the threshold pump power increases for TE pumping.
Physicochemical characteristics and phenotypic diversity of sicilian winter pumpkin (Cucurbita maxima) populations
2017
Six pumpkin genotypes (G1, G2, G3, G4, G5 and G6) were evaluated for their morphological, agronomical and physico-chemical properties under ecological conditions of Sicily (Italy). Considering the agronomical, morphological and physicochemical data including fiber, humidity, pH, total acidity, soluble solids, carotenoids, phenolic and ascorbic acid content, it was possible to differentiate among genotypes. The morphological analysis showed that the pumpkin genotypes did not have a homogenous morphology and present a large physico-chemical characteristic variability. Furthermore, high contents of carotenoids and dietary fiber, soluble solids, phenolic and ascorbic acid were observed with the…
Near-IR-to-visible emission in ytterbium-doped silica fiber at in-core 488-nm pumping
2008
We report near-IR-to-visible broadband emission in Ytterbium-doped silicate fiber (YF) at 488-nm in-core excitation. This emission is revealed to originate from Yb3+-Yb3+ pair clusters (900 – 1200-nm band), whose presence is proved by a separate study of cooperative processes in the fiber, and Yb2+ phototropic centers (600 – 900-nm band) provisionally accepted to be present in the YF.
Mode-locked Yb-doped all-fiber laser based on in-fiber acoustooptic modulation
2011
We show what we believe is the first demonstration of an ytterbium-doped strictly all-fiber active mode-locking laser. The active control of the laser is based on in-fiber amplitude modulation at 11 MHz, which is achieved by using an all-fiber acoustooptic superlattice modulator driven by standing acoustic waves. In our experiments, the laser was operated at 1091.3 nm and had two stable regimes producing either a train of mode-locked single pulses or a train of pulse pairs. Best results for the mode-locked train of single pulses were 740 ps of time width and 26 mW of average power, at a pump power of 480 mW.
SELECTIVE AMPLIFICATION OF NARROW RESONANCE FORMED IN TRANSMISSION SPECTRUM OF Rb NANO-CELL IN MAGNETIC FIELD
2012
Recently it was shown that "λ-Zeeman Technique" (λ-ZT) is a convenient tool to study individual transitions between the Zeeman sublevels of hyperfine levels in an external magnetic field. λ-ZT is based on resonant transmission spectrum of nanometric thin cell (NTC) of thickness L = λ, where λ is the resonant wavelength 794 nm for Rb D1 line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field. Examination of VSOP resonances allows one to identify and investigate an atomic transition in the range of magnetic fields 10 - 5000 G. Here we present a new method for selective addressing of VSOP r…
Lāčplēša tēma latviešu apziņā, literatūrā, mākslā un LU mācībspēku pētījumos
2022
Atzīmējot Andreja Pumpura eposa “Lāčplēsis” 135. gadadienu, kas aprit 2023. gada jūnijā, Humanitāro zinātņu bibliotēkā tika izveidota izstāde "Lāčplēša tēma latviešu apziņā, literatūrā, mākslā un LU mācībspēku pētījumos". Eposs tika publicēts 1888. gada jūnijā saistībā ar Trešo Vispārējo latviešu dziesmu svētku norisēm. Darbs tapis, sintezējot teikas, pasakas un laikabiedru priekšstatus par senatni, saskaņā ar 19. gs. nacionālā romantisma idejām Eiropā laikā, kad eposa esamība tika uztverta kā nācijas eksistences apliecinājums. Izstāde izkārtota 4 plauktos. Pirmajā plauktā izstādīts eposa 1888.gada izdevums. Otrajā plauktā redzami Latvijas Universitātes mācībspēku pētījumi, skatot Lāčplēsi …
Transient collisionally excited X-ray laser in nickel-like zirconium pumped with the PHELIX laser facility
2004
A transient collisionally excited X-ray laser has been put into operation using the front end of the PHELIX laser system as a pump laser. Strong lasing at 22 nm has been observed in nickel-like zirconium.