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131.
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133.
Ming-Fong Tsai Naveen Chilamkurti Ce-Kuen Shieh Alexey Vinel 《Mathematical and Computer Modelling》2011,53(11-12):2067-2077
Wireless transmission suffers from poor wireless channel conditions, such as high bit error rate and error bursts resulting from channel fading and radio interference. The MAC-level Forward Error Correction (MFEC) mechanism is proposed to solve these problems. The MFEC mechanism cannot only adaptively adjust Forward Error Correction (FEC) redundancy, depending on the network condition, but can also retransmit whole packets even if the error packet includes several bit errors. In this paper, an Adaptive MAC-level FEC (AMFEC) mechanism is proposed to improve wireless transmission quality. The AMFEC mechanism relies on the effective packet loss rate model to dynamically adjust MFEC redundancy in order to minimize error recovery overhead. The AMFEC mechanism will retransmit the error of sub-packets and increase FEC redundancy to reduce transmission redundancy. The AMFEC mechanism not only enhances the quality of wireless transmission but also reduces the overhead of retransmission. The experimental results show the AMFEC mechanism is better than conventional MFEC mechanisms. 相似文献
134.
135.
Naveen Bijalwan 《International Journal of Theoretical Physics》2012,51(1):23-34
General exact higher-dimensional (n+2), n>2 solutions in general theory of relativity of Einstein-Maxwell field equations for spherically symmetric distribution of
charged pressure perfect fluid are expressed in terms of pressure extending 4-dimensional solutions presented by Bijalwan
(Astrophys. Space Sci. 2011, doi:). Subsequently, metrics (e
λ
and e
υ
), matter density and electric intensity are expressible in terms of pressure. Consequently, Pressure is found to be an invertible
arbitrary function of ω (=c
1+c
2
r
2), where c
1 and c
2 (≠0) are arbitrary constants, and r is the radius of star, i.e. p=p(ω). We present a general solution for charged pressure fluid in terms for ω. We list and discuss some old and new solutions which fall in this category. Also, these solutions satisfy barotropic equation
of state relating the radial pressure to the energy density. But we noticed that none of these solutions in terms of pressure
for charged fluids has a well behaved neutral counter part for a spatial component of metric e
λ
i.e. choosing same spatial component for charged and neutral fluid. To illustrate the approach, we discovered a new solution
for extended charged analogues of Schwarzschild interior solution in higher dimensions which is found to be well behaved only
for n=2. The maximum mass found to be 1.512 M
Θ with linear dimension 14.964 km. Physical quantities pressure, energy density, red-shift, velocity of sound and p/c
2
ρ are well behaved and monotonically decreasing towards the surface while adiabatic index and charge density are monotonically
increasing. For brevity we don’t discuss the numerical results in detailed. 相似文献
136.
Naveen Kumar Saxena Nitendar Kumar 《Journal of magnetism and magnetic materials》2010,322(18):2641-865
In this paper the characteristics of LiTiMg-ferrite radome are presented. A thin layer of LiTiMg-ferrite is used as superstrate or radome, which controls the radiation, reception, and scattering from a printed antenna or array by applying a dc magnetic bias field in the plane of the ferrite, orthogonal to the RF magnetic field. In this analysis absorbing and transmission power coefficients are calculated to obtain the power loss and transmitted power through the radome layer respectively. The absorbing power coefficient verifies the switching behavior of radome for certain range of applied external magnetic field (Ho), which depends on the resonance width parameter (ΔH) of ferrite material. By properly choosing the bias field, electromagnetic wave propagation in the ferrite layer can be made zero or negligible over a certain frequency range, resulting in switching behavior of the ferrite layer. In this communication we also show precise preparation of radome layer and present its electric and magnetic properties along with its Curie temperature, which shows the working efficiency of layer under extreme situation. This radome layer can be very useful for the sensitive and smart communication systems. 相似文献
137.
D.P. Rojas J. Rodríguez Fernández J.C. Gómez Sal F.G. Gandra A.N. Medina 《Journal of magnetism and magnetic materials》2010,322(20):3192-3195
We have investigated the crystallographic, magnetic and thermodynamic properties of the as-cast and annealed Ce2NiSi3 alloys, crystallizing in the AlB2-type hexagonal structure. The DC-magnetic susceptibility data show that the as-cast sample exhibits an antiferromagnetic (AFM) ordering below TN= 3.8 K, whereas the annealed sample shows, at 4.2 K, a magnetic transition of AFM nature and, around 2.5 K, an additional anomaly. The specific heat shows a peak with at 3.8 K for the as cast sample, which shifts to lower temperatures when the magnetic field increases, consistent with the antiferromagnetic nature of the transition. On the other hand, in the annealed alloy, the maximum of the specific heat peak reaches at 4.2 K, and no additional anomalies were observed. The different magnetic behavior between the as-cast and annealed samples is attributed to thermal effects on the structural disorder of nickel and silicon atoms, as already observed in other isotypic R2TSi3 alloys, where R=U or Ce, and T= transition metal. 相似文献
138.
A new approach to prepare and characterize double network elastomeric systems was investigated. A styrene‐ethylene‐co‐butylene‐styrene (SEBS) triblock copolymer system containing physical crosslinks was used to achieve a double network by additional crosslinking using ultra‐violet (UV) light. An ethylene–propylene–diene monomer (EPDM) terpolymer system containing chemical crosslinks was used to achieve a conventional double network using UV crosslinking. Properties from conventional monotonic tensile tests, dynamic mechanical analysis, and thermomechanical properties were investigated. These double network elastomers show a transition between competitive and collaborative behavior in their mechanical properties and lower coefficients of thermal expansion arising from a competition of the networks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 778–789, 2010 相似文献
139.
T.M. Aliev S. Rai Choudhury A.S. Cornell Naveen Gaur 《The European Physical Journal C - Particles and Fields》2007,49(3):657-664
Standard model (SM) CP asymmetries in B→Kℓ+ℓ- are expected to be very small. This feature could help in the understanding of new physics scenarios which predict the existence
of CP odd phases in various Wilson coefficients. In this paper we have analyzed the B→Kℓ+ℓ- decay in scenarios beyond the SM where the Wilson coefficients have new CP odd phases. The sensitivity of the CP asymmetries
on these new weak phases is discussed.
PACS 13.20.He; 12.60.-i; 13.88.+e 相似文献
140.