480 research outputs found
Impact of surface reflection on transmission eigenvalue statistics and energy distributions inside random media
The impact of surface reflection upon transmission through and energy
distributions within random media has generally been described in terms of the
boundary extrapolation lengths at the input and output end of an
open sample, which are the distance beyond the sample surfaces at which the
energy density within the sample extrapolates to zeroThe importance of
reflection at the sample boundaries plays a key role in the scaling of
transmission. Here we consider the impact of surface reflection on the
propagation of diffusive waves in terms of the modification of the distribution
of transmission eigenvalues (DTE). We review our finding of a transition in the
analytical form of the DTE at the point that the sample length equals
. The highest transmission eigenvalue for stronger asymmetry in
boundary reflection is strictly smaller than unity. The average transmission
and profiles of energy density inside the sample can still be described in
terms of the sample length, , and the boundary extrapolation lengths on both
sides of the sample, . For localized waves, we find the energy
density profile within the sample is a segment of the distribution that would
be found in a longer sample with length . These results suggest new
ways of controlling wave interference in both diffusive and localized systems
by varying boundary reflectivity
Adaptive Power Load Balancing in Cellular Networks
Load balancing in mobile cellular networks is an important mechanism that enables distribution of demand across neighboring cells, which is critical for better resource utilization and user satisfaction. Current approaches for load balancing are reactive, redistributing users only when the offered load approaches the cell capacity. This approach can lead to deteriorated network performance and user experience. In order to better cater to users, mobile networks need to be proactive and provision resources based on expected demand. To this end we propose a load balancing mechanism that allows for proactive network configuration based on prediction of traffic load. Our approach makes use of power control mechanisms to reconfigure the coverage of a mobile base station and thus control the amount of users and offered load at that base station. We apply our method on a real-world cellular network in Senegal and show that it enables better distribution of load in Orange Telecom’s network in Senegal
An insight of p-type to n-type conductivity conversion in oxygen ion-implanted ultrananocrystalline diamond films by impedance spectroscopy
The impedance spectroscopy measurements were used to investigate the separated contributions of diamond grains and grain boundaries (GBs), giving an insight into p-type to n-type conductivity conversion in O+-implanted ultrananocrystalline diamond (UNCD) films. It is found that both diamond grains and GBs promote the conductivity in O+-implanted UNCD films, in which GBs make at least half contribution. The p-type conductivity in O+-implanted samples is a result of H-terminated diamond grains, while n-type conductive samples are closely correlated with O-terminated O+-implanted diamond grains and GBs in the films. The results also suggest that low resistance of GBs is preferable to obtain high mobility n-type conductive UNCD films
Dependence of quantum correlations of twin beams on pump finesse of optical parametric oscillator
The dependence of quantum correlation of twin beams on the pump finesse of an
optical parametric oscillator is studied with a semi-classical analysis. It is
found that the phase-sum correlation of the output signal and idler beams from
an optical parametric oscillator operating above threshold depends on the
finesse of the pump field when the spurious pump phase noise generated inside
the optical cavity and the excess noise of the input pump field are involved in
the Langevin equations. The theoretical calculations can explain the previously
experimental results, quantitatively.Comment: 27 pages, 8 figure
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Marjolin’s ulcer: a preventable malignancy arising from scars
Background: Marjolin’s ulcer (MU) is a rare malignancy arising from various forms of scars. This potentially fatal complication typically occurs after a certain latency period. This article attempts to reveal the importance of the latency period in the prevention and early treatment of the malignancy. Methods: A retrospective review of 17 MU patients who underwent surgical procedures between June of 2005 and December 2011 was conducted. Etiology of injuries, latency period, repeated ulceration, and outcomes were recorded. This observational report reveals characteristics of patients who develop MU. Results: An incidence of 0.7% of MU was found amongst patients complaining of existing scars in our study; burns and trauma were the most common etiology of MU. The mean latency period was 29 years (SD = 19) and the mean post-ulceration period was 7 years (SD = 9). Statistical analysis revealed a negative correlation between the age of patients at injury and the length of latency period (r = −0.8, P <0.01), as well as the lengths of pre-ulceration and post-ulceration periods (r = −0.7, P <0.01). Conclusions: Patients experience different lengths of pre- and post-ulceration periods during the latency period. Younger patients tend to have a longer latency period. Skin breakdown on chronic scars and chronic unhealed ulcers are two main sources of MU. MU may be preventable with a close surveillance of the ulcer during the latency period
On the Toda Lattice Equation with Self-Consistent Sources
The Toda lattice hierarchy with self-consistent sources and their Lax
representation are derived. We construct a forward Darboux transformation (FDT)
with arbitrary functions of time and a generalized forward Darboux
transformation (GFDT) for Toda lattice with self-consistent sources (TLSCS),
which can serve as a non-auto-Backlund transformation between TLSCS with
different degrees of sources. With the help of such DT, we can construct many
type of solutions to TLSCS, such as rational solution, solitons, positons,
negetons, and soliton-positons, soliton-negatons, positon-negatons etc., and
study properties and interactions of these solutions.Comment: 20 page
Altering the wetting properties of orthopaedic titanium alloy (Ti–6Al–7Nb) using laser shock peening
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