713 research outputs found
Wave Profile for Anti-force Waves with Maximum Possible Currents
In the theoretical investigation of the electrical breakdown of a gas, we apply a one-dimensional, steady state, constant velocity, three component fluid model and consider the electrons to be the main element in propagation of the wave. The electron gas temperature, and therefore the electron gas partial pressure, is considered to be large enough to provide the driving force. The wave is considered to have a shock front, followed by a thin dynamical transition region. Our set of electron fluid-dynamical equations consists of the equations of conservation of mass, momentum, and energy, plus the Poisson\u27s equation. The set of equations is referred to as the electron fluid dynamical equations; and a successful solution therefor must meet a set of acceptable physical conditions at the trailing edge of the wave. For breakdown waves with a significant current behind the shock front, modifications must be made to the set of electron fluid dynamical equations, as well as the shock condition on electron temperature. Considering existence of current behind the shock front, we have derived the shock condition on electron temperature, and for a set of experimentally measured wave speeds, we have been able to find maximum current values for which solutions to our set of electron velocity, electron temperature, and electron number density within the dynamical transition region of the wave
Wave Profile for Current Bearing Antiforce Waves
For fluid dynamical analysis of breakdown waves, we employ a one-dimensional, three-component (electrons, ions and neutral particles) fluid model to describe a steady-state, ionizing wave propagating counter to strong electric fields. The electron gas temperature and therefore the electron fluid pressure is assumed to be large enough to sustain the wave motion down the discharge tube. Such waves are referred to as antiforce waves. The complete set of equations describing such waves consists of the equations of conservation of mass, momentum and energy coupled with Poisson’s equation. Inclusion of current behind the wave front alters the set of electron fluid dynamical equations and also the boundary condition on electron temperature. For a range of experimentally observed current values, using the modified boundary condition on electron temperature, we have been able to integrate our modified set of electron fluid dynamical equations through the Debye layer. Our solutions meet the expected boundary conditions at the trailing edge of the wave. We present the wave profile for electric field, electron velocity, electron number density and electron temperature within the Debye layer of the wave
Low Speed Current Bearing Anti-force Waves
For theoretical investigation of electrical breakdown of a gas, we apply a one-dimensional, steady profile, constant velocity, three-component (electrons, ions and neutral particles) fluid model. Our fluid model consists of the equations of conservation of mass, momentum and energy, coupled with the Poison’s equation. The set of equations is referred to as the electron fluid dynamical equations (EFD). This investigation involves breakdown waves with a substantial current behind the wave front, and waves for which the electric field force on electrons is in the opposite direction of the wave propagation (anti-force waves – lightning return stroke). Therefore, the set of electron fluid dynamical equations need to be modified. For a low wave speed, we intend to find current values, and also the maximum current, for which solutions for our set of electron fluid dynamical equations become possible
Monte Carlo simulations of magnetic ordering in the fcc Kagome lattice
Monte Carlo simulation results are reported on magnetic ordering in ABC
stacked Kagom\'{e} layers with fcc symmetry for both XY and Heisenberg models
which include exchange interactions with the eight near-neighbors. Well known
degeneracies of the 2D system persist in the 3D case and analysis of the
numerical data provides strong evidence for a fluctuation-driven first-order
transition to well-defined long-range order characterized as the layered
(120-degree) spin structure. Effects of varying the inter-layer coupling are
also examined. The results are relevant to understanding the role of
frustration in IrMn alloys widely used by the magnetic storage industry as
thin-films in the antiferromagnetic pinning layer in GMR and TMR spin valves.
Despite the technological importance of this structure, it has not previously
been noted that the magnetic Mn-ions of fcc IrMn form Kagom\'{e} layers.Comment: 9 pages, 14 figures. Submitted to Phys. Rev.
Zero Energy Building by Multi-Carrier Energy Systems including Hydro, Wind, Solar and Hydrogen
This paper proposes a unified solution to address the energy issues in net zero energy building (ZEB), as a new contribution to earlier studies. The multi carrier energy system including hydro-wind-solar-hydrogen-methane-carbon dioxide-thermal energies is integrated and modeled in ZEB. The electrical sector is supplied by hydro-wind-solar, combined heat and power, and pumped hydro storage. The purpose is to minimize the released CO2 to the atmosphere while all the electrical-thermal load demands are successfully supplied following events and disruptions. The model improves the energy resilience and minimizes the environmental pollutions simultaneously. The results demonstrate that the developed model reduces the CO2 pollution by about 33451 kg per year. The model is a resilient energy system that can handle all failures of components and supply both the thermal and electrical loads following events. The model can efficiently handle 26% increment in the electrical loads and 110% increment in the thermal loads.© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.fi=vertaisarvioitu|en=peerReviewed
hints to chromosomal instability after irradiation
Background Total body irradiation (TBI) has been part of standard conditioning
regimens before allogeneic stem cell transplantation for many years. Its
effect on normal tissue in these patients has not been studied extensively.
Method We studied the in vivo cytogenetic effects of TBI and high-dose
chemotherapy on skin fibroblasts from 35 allogeneic stem cell transplantation
(SCT) patients. Biopsies were obtained prospectively (n = 18 patients) before,
3 and 12 months after allogeneic SCT and retrospectively (n = 17 patients)
23–65 months after SCT for G-banded chromosome analysis. Results Chromosomal
aberrations were detected in 2/18 patients (11 %) before allogeneic SCT, in
12/13 patients (92 %) after 3 months, in all patients after 12 months and in
all patients in the retrospective group after allogeneic SCT. The percentage
of aberrant cells was significantly higher at all times after allogeneic SCT
compared to baseline analysis. Reciprocal translocations were the most common
aberrations, but all other types of stable, structural chromosomal aberrations
were also observed. Clonal aberrations were observed, but only in three cases
they were detected in independently cultured flasks. A tendency to non-random
clustering throughout the genome was observed. The percentage of aberrant
cells was not different between patients with and without secondary
malignancies in this study group. Conclusion High-dose chemotherapy and TBI
leads to severe chromosomal damage in skin fibroblasts of patients after SCT.
Our long-term data suggest that this damage increases with time, possibly due
to in vivo radiation-induced chromosomal instability
Multicarrier Microgrid Operation Model Using Stochastic Mixed Integer Linear Programming
The microgrid operation is addressed in this article based on a multicarrier energy hub. Natural gas, electricity, heating, cooling, hydrogen, carbon dioxide, and renewable energies are considered as the energy carriers. The designed microgrid optimizes and utilizes a wide range of resources at the same time including renewables, electrical storage, hybrid storage, heating-cooling storage, electric vehicles (EVs) charging station, power to gas unit, combined cooling-heating-power, and carbon capture-storage. The purpose is to reduce the environmental pollutions and operating costs. The resilience and flexibility of the energy hub is also improved. Vehicle to grid and fully-partial charge models are incorporated for EVs to improve the system resilience and supplying the critical loads following events. Different events are modeled to evaluate the system resilience. The model is expressed as a stochastic mixed integer linear programming problem. Both active and reactive powers are modeled. The microgrid is simulated under four different cases. The results show that the multitype energy storages reduce the annual cost of energy while the integrated charging station can decrease the load shedding.©2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.fi=vertaisarvioitu|en=peerReviewed
Boundary Condition on Electron Temperature for Antiforce Current Bearing Waves
In our investigation of breakdown waves, we apply a one-dimensional, three-component, steady-state fluid model. The wave is considered to be shock fronted and the electrons are assumed to be the main element in propagation of the wave. In our fluid model, the electron gas temperature is assumed to be large enough to sustain the wave motion. Our set of fluid equations is composed of the equations of conservation of mass, momentum and energy plus the Poisson’s equation. This investigation involves breakdown waves for which a large current exist in the vicinity of the wave front. Existence of current behind the wave front alters the equation of conservation of energy and also the Poisson’s equation. Therefore, the boundary conditions at the shock front will change as well. For current bearing breakdown waves we will derive the appropriate boundary condition for electron temperature, and using the new boundary condition, we will integrate the fluid dynamical equations through the dynamical transition region of the wav
The Temperature of the CMB at 10 GHz
We report the results of an effort to measure the low frequency portion of
the spectrum of the Cosmic Microwave Background Radiation (CMB), using a
balloon-borne instrument called ARCADE (Absolute Radiometer for Cosmology,
Astrophysics, and Diffuse Emission). These measurements are to search for
deviations from a thermal spectrum that are expected to exist in the CMB due to
various processes in the early universe. The radiometric temperature was
measured at 10 and 30 GHz using a cryogenic open-aperture instrument with no
emissive windows. An external blackbody calibrator provides an in situ
reference. A linear model is used to compare the radiometer output to a set of
thermometers on the instrument. The unmodeled residuals are less than 50 mK
peak-to-peak with a weighted RMS of 6 mK. Small corrections are made for the
residual emission from the flight train, atmosphere, and foreground Galactic
emission. The measured radiometric temperature of the CMB is 2.721 +/- 0.010 K
at 10 GHz and 2.694 +/- 0.032 K at 30 GHz.Comment: 8 pages including 5 figures. Submitted to The Astrophysical Journa
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