827,293 research outputs found
Zonal Jets as Transport Barriers in Planetary Atmospheres
The connection between transport barriers and potential vorticity (PV)
barriers in PV-conserving flows is investigated with a focus on zonal jets in
planetary atmospheres. A perturbed PV-staircase model is used to illustrate
important concepts. This flow consists of a sequence of narrow eastward and
broad westward zonal jets with a staircase PV structure; the PV-steps are at
the latitudes of the cores of the eastward jets. Numerically simulated
solutions to the quasigeostrophic PV conservation equation in a perturbed
PV-staircase flow are presented. These simulations reveal that both eastward
and westward zonal jets serve as robust meridional transport barriers. The
surprise is that westward jets, across which the background PV gradient
vanishes, serve as robust transport barriers. A theoretical explanation of the
underlying barrier mechanism is provided. It is argued that transport barriers
near the cores of westward zonal jets, across which the background PV gradient
is small, are found in Jupiter's midlatitude weather layer and in the Earth's
summer hemisphere subtropical stratosphere.Comment: Accepted for publication in JA
Isolation of three novel rat and mouse papillomaviruses and their genomic characterization.
Despite a growing knowledge about the biological diversity of papillomaviruses (PV), only little is known about non-human PV in general and about PV mice models in particular. We cloned and sequenced the complete genomes of two novel PV types from the Norway rat (Rattus norvegicus; RnPV2) and the wood mouse (Apodemus sylvaticus; AsPV1) as well as a novel variant of the recently described MmuPV1 (originally designated as MusPV) from a house mouse (Mus musculus; MmuPV1 variant). In addition, we conducted phylogenetic analyses using a systematically representative set of 79 PV types, including the novel sequences. As inferred from concatenated amino acid sequences of six proteins, MmuPV1 variant and AsPV1 nested within the Beta+Xi-PV super taxon as members of the Pi-PV. RnPV2 is a member of the Iota-PV that has a distant phylogenetic position from Pi-PV. The phylogenetic results support a complex scenario of PV diversification driven by different evolutionary forces including co-divergence with hosts and adaptive radiations to new environments. PV types particularly isolated from mice and rats are the basis for new animal models, which are valuable to study PV induced tumors and new treatment options
Modeling and Simulation of Solar Photovoltaic Cell for the Generation of Electricity in UAE
This paper proposes the implementation of a circuit based simulation for a
Solar Photovoltaic (PV) cell in order to get the maximum power output. The
model is established based on the mathematical model of the PV module. As the
PV cell is used to determine the physical and electrical behavior of the cell
corresponding to environmental factors such as temperature and solar
irradiance, this paper evaluates thirty years solar irradiation data in United
Arab Emirates (UAE), also analyzes the performance parameters of PV cell for
several locations. Based on the Shockley diode equation, a solar PV module is
presented. However, to analyze the performance parameters, Solarex MSX 120, a
typical 120W module is selected. The mathematical model for the chosen module
is executed in Matlab. The consequence of this paper reflects the effects of
variation of solar irradiation on PV cell within UAE. Conclusively, this paper
determines the convenient places for implementing the large scale solar PV
modules within UAE.Comment: To be published in 5th International Conference on Advances in
Electrical Engineering (ICAEE-2019
Design of fibre reinforced PV concepts for building integrated applications
Fibre reinforced polymers present an interesting encapsulation medium for PV-modules. Glass fibres can provide increased strength and stiffness to thin polymer layers overcoming the brittleness and limited deformability of glass-panes. Glass fibre reinforced polymers allows for transparency over a broad range of the solar spectrum while the material properties and integral production processes create possibilities for novel product concepts with embedded PV technology. To explore such possibilities, innovative design methods were used to design novel PV product concepts for applications in the build environment.\ud
In our paper three conceptual designs are presented; (1) a thin film module with an adjoining interconnection system functioning as structural element for geodetic roofing structures, (2) a PV lamella with single-axis tracking utilizing a linear concentration effect caused by the geometry of the product and the materials applied, and (3) a prepreg PV-material which allows for easy shaping during the production of PV modules with complex geometries. Each concept employs a specific PV technology and demonstrates a possible application aimed at a specific market. In this way we show the potential of integration of PV technology in fibre reinforced composites. The paper will be illustrated by concept renderings
3D simulation of complex shading affecting PV systems taking benefit from the power of graphics cards developed for the video game industry
Shading reduces the power output of a photovoltaic (PV) system. The design
engineering of PV systems requires modeling and evaluating shading losses. Some
PV systems are affected by complex shading scenes whose resulting PV energy
losses are very difficult to evaluate with current modeling tools. Several
specialized PV design and simulation software include the possibility to
evaluate shading losses. They generally possess a Graphical User Interface
(GUI) through which the user can draw a 3D shading scene, and then evaluate its
corresponding PV energy losses. The complexity of the objects that these tools
can handle is relatively limited. We have created a software solution, 3DPV,
which allows evaluating the energy losses induced by complex 3D scenes on PV
generators. The 3D objects can be imported from specialized 3D modeling
software or from a 3D object library. The shadows cast by this 3D scene on the
PV generator are then directly evaluated from the Graphics Processing Unit
(GPU). Thanks to the recent development of GPUs for the video game industry,
the shadows can be evaluated with a very high spatial resolution that reaches
well beyond the PV cell level, in very short calculation times. A PV simulation
model then translates the geometrical shading into PV energy output losses.
3DPV has been implemented using WebGL, which allows it to run directly from a
Web browser, without requiring any local installation from the user. This also
allows taken full benefits from the information already available from
Internet, such as the 3D object libraries. This contribution describes, step by
step, the method that allows 3DPV to evaluate the PV energy losses caused by
complex shading. We then illustrate the results of this methodology to several
application cases that are encountered in the world of PV systems design.Comment: 5 page, 9 figures, conference proceedings, 29th European Photovoltaic
Solar Energy Conference and Exhibition, Amsterdam, 201
Meeting Global Cooling Demand with Photovoltaics during the 21st Century
Space conditioning, and cooling in particular, is a key factor in human
productivity and well-being across the globe. During the 21st century, global
cooling demand is expected to grow significantly due to the increase in wealth
and population in sunny nations across the globe and the advance of global
warming. The same locations that see high demand for cooling are also ideal for
electricity generation via photovoltaics (PV). Despite the apparent synergy
between cooling demand and PV generation, the potential of the cooling sector
to sustain PV generation has not been assessed on a global scale. Here, we
perform a global assessment of increased PV electricity adoption enabled by the
residential cooling sector during the 21st century. Already today, utilizing PV
production for cooling could facilitate an additional installed PV capacity of
approximately 540 GW, more than the global PV capacity of today. Using
established scenarios of population and income growth, as well as accounting
for future global warming, we further project that the global residential
cooling sector could sustain an added PV capacity between 20-200 GW each year
for most of the 21st century, on par with the current global manufacturing
capacity of 100 GW. Furthermore, we find that without storage, PV could
directly power approximately 50% of cooling demand, and that this fraction is
set to increase from 49% to 56% during the 21st century, as cooling demand
grows in locations where PV and cooling have a higher synergy. With this
geographic shift in demand, the potential of distributed storage also grows. We
simulate that with a 1 m water-based latent thermal storage per household,
the fraction of cooling demand met with PV would increase from 55% to 70%
during the century. These results show that the synergy between cooling and PV
is notable and could significantly accelerate the growth of the global PV
industry
Future Directions in Parity Violation: From Quarks to the Cosmos
I discuss the prospects for future studies of parity-violating (PV)
interactions at low energies and the insights they might provide about open
questions in the Standard Model as well as physics that lies beyond it. I cover
four types of parity-violating observables: PV electron scattering; PV hadronic
interactions; PV correlations in weak decays; and searches for the permanent
electric dipole moments of quantum systems.Comment: Talk given at PAVI 06 workshop on parity-violating interactions,
Milos, Greece (May, 2006); 10 page
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