373 research outputs found
First-Principles Calculation of Electric Field Gradients and Hyperfine Couplings in YBa2Cu3O7
The local electronic structure of YBa2Cu3O7 has been calculated using
first-principles cluster methods. Several clusters embedded in an appropriate
background potential have been investigated. The electric field gradients at
the copper and oxygen sites are determined and compared to previous theoretical
calculations and experiments. Spin polarized calculations with different spin
multiplicities have enabled a detailed study of the spin density distribution
to be made and a simultaneous determination of magnetic hyperfine coupling
parameters. The contributions from on-site and transferred hyperfine fields
have been disentangled with the conclusion that the transferred spin densities
essentially are due to nearest neighbour copper ions only with marginal
influence of ions further away. This implies that the variant temperature
dependencies of the planar copper and oxygen NMR spin-lattice relaxation rates
are only compatible with commensurate antiferromagnetic correlations. The
theoretical hyperfine parameters are compared with those derived from
experimental data.Comment: 14 pages, 12 figures, accepted to appear in EPJ
MULTI-CHANNEL MAC PROTOCOL FOR ENERGY SAVING IN WIRELESS SENSOR NETWORKS
Wireless Sensor Network (WSN) is a self-organizing and distributed collection of small sensor nodes with limited energy are connected wirelessly to the sink, where the information is needed. The significant trait for any Wireless Sensor Network is power consumption since WSNs finds its most of the applications in unsafe, risky areas like Volcano eruption identification, Warfield monitoring, where human intervention is less or not possible at all. Hence designing a protocol with minimum energy consumption as a concern is an important challenge in increasing the lifetime of the sensor networks. Medium Access Control (MAC) Layer of WSN consumes much of the energy as it contains the radio component. Energy problems in MAC layer include collision, idle listening, and protocol overhead. Our Proposed MAC protocol provides solution for the problem of: collision by providing multiple channels; idle listening by providing sleeping mechanism for the nodes other than the active node; overhead by reducing the number of control messages. Avoiding collision results in the decrease in number of retransmissions which consumes more energy, avoiding idle listening problem will fairly increase the lifetime of the sensor node as well as the network’s lifetime and reducing overhead in turn consumes less energy
First principles study of local electronic and magnetic properties in pure and electron-doped NdCuO
The local electronic structure of Nd2CuO4 is determined from ab-initio
cluster calculations in the framework of density functional theory.
Spin-polarized calculations with different multiplicities enable a detailed
study of the charge and spin density distributions, using clusters that
comprise up to 13 copper atoms in the CuO2plane. Electron doping is simulated
by two different approaches and the resulting changes in the local charge
distribution are studied in detail and compared to the corresponding changes in
hole doped La2CuO4. The electric field gradient (EFG) at the copper nucleus is
investigated in detail and good agreement is found with experimental values. In
particular the drastic reduction of the main component of the EFG in the
electron-doped material with respect to LaCuO4 is explained by a reduction of
the occupancy of the 3d3z^2-r^2 atomic orbital. Furthermore, the chemical
shieldings at the copper nucleus are determined and are compared to results
obtained from NMR measurements. The magnetic hyperfine coupling constants are
determined from the spin density distribution
Analisis Kehilangan Energi pada Pipa Transmisi SPAM Kecamatan Mempura
Clean water obtained by the community District Mempura is still minimal. This is of course caused by many factors such as reservoir and flow in pipes. Water Supply System (WSS) District Mempura using EPANET 2.0 software with 3 (three) alternative transmission pipes each diameter 6 inch, 8 inch and 10 inch. Projection of population of District Mempura using Geometric method until 2035 is 27.262 soul and requirement of clean water equal to 37 liter / second. From 3 (alternative), 10 inch pipe transmission line is used with flow rate 0,79 m / s, head at node A1 equal to 16,13 meter, pressure value 4,25 meter and headloss 2,31 / 1000 meter
Dzyaloshinsky-Moriya antisymmetric exchange coupling in cuprates: Oxygen effects
We revisit a problem of Dzyaloshinsky-Moriya antisymmetric exchange coupling
for a single bond in cuprates specifying the local spin-orbital contributions
to Dzyaloshinsky vector focusing on the oxygen term. The Dzyaloshinsky vector
and respective weak ferromagnetic moment is shown to be a superposition of
comparable and, sometimes, competing local Cu and O contributions. The
intermediate oxygen O Knight shift is shown to be an effective tool to
inspect the effects of Dzyaloshinsky-Moriya coupling in an external magnetic
field. We predict the effect of oxygen weak antiferromagnetism in
edge-shared CuO chains due to uncompensated oxygen Dzyaloshinsky vectors.
Finally, we revisit the effects of symmetric spin anisotropy, in particular,
those directly induced by Dzyaloshinsky-Moriya coupling.Comment: 12 pages, 2 figures, submitted to JET
Travelling and sticky affects: : Exploring teens and sexualized cyberbullying through a Butlerian-Deleuzian- Guattarian lens
In this paper we combine the thinking of Deleuze and Guattari (1984, 1987) with Judith Butler’s (1990, 1993, 2004, 2009) work to follow the rhizomatic becomings of young people’s affective relations in a range of on- and off-line school spaces. In particular we explore how events that may be designated as sexual cyberbullying are constituted and how they are mediated by technology (such as texting or in/through social networking sites). Drawing on findings from two different studies looking at teens’ uses of and experiences with social networking sites, Arto in Denmark, and Bebo in the UK, we use this approach to think about how affects flow, are distributed, and become fixed in assemblages. We map how affects are manoeuvred and potentially disrupted by young people, suggesting that in the incidences discussed affects travel as well as stick in points of fixation. We argue that we need to grasp both affective flow and fixity in order to gain knowledge of how subjectification of the gendered/classed/racialised/sexualised body emerges. A Butlerian-Deleuzian-Guattarian frame helps us to map some of these affective complexities that shape sexualized cyberbully events; and to recognize technologically mediated lines of flight when subjectifications are at least temporarily disrupted and new terms of recognition and intelligibility staked out. Keywords
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