1,652 research outputs found
An Ant Colony Optimization based Routing Techniques for VANET
With number of moving vehicles, vehicular Ad Hoc Network (VANET) is formed. These are provided with the wireless connections. Among various challenges in the VANET such as security and privacy of the messages, data forwarding is also considered as a major challenge. The effective communication is mainly depends on the how safely and fast the data is being forwarded among the vehicles. Data forwarding using Greedy mechanism suitable for routing in the VANETs, it depends only on the position of nodes and also data forwarding is done with minimum number of hops. In this paper, Position based GPCR and topology based DYMO routing protocol are adapted to make the use of Ant Colony Optimization (ACO) procedures. The resulting bio-inspired protocols, ACO_GPCR and ACO_DYMO had its performance evaluated and compared against existing GPCR and DYMO routing protocols. The obtained results suggest that making the use of ACO algorithm make these protocols more efficient in terms of Delay, Jitter, Packet Delivery Ratio and energy consumption
Morphometric studies in the genus Clerodendrum L.
Six Clerodendrum L. species from Kolhapur district were morphometrically analyzed with the help of PCA, cluster analysis and CD. It was observed that the quantitative characters viz. petiole length, leaf length and leaf width have great significance in delimitation of all the species and corolla tube length, leaf width, gynoecium length and leaf length have great contribution in separation of the taxa. Clerodendrum multiflorum (Burm.f.) O. Ktze.- Clerodendrum inerme (L.) Gaertn., Clerodendrum paniculatum L. - Clerodendrum viscosum Vent. and Clerodendrum inerme (L.) Gaertn. - Clerodendrum serratum (L.) Moon. are very closely related with each other and Clerodendrum multiflorum (Burm.f.) O.Ktze.- Clerodendrum paniculatum L. and Clerodendrum multiflorum (Burm.f.) O. Ktze. - Clerodendrum viscosum Vent. are significantly different from each other
A Novel Histogram-Based Multi-Threshold Searching Algorithm for Multilevel Color Thresholding
[[abstract]]Image segmentation is an important preliminary process required in object tracking applications. This paper addresses the issue of unsupervised multi‐colour thresholding design for colour‐based multiple objects segmentation. Most of the current unsupervised colour thresholding techniques require adopting a supervised training algorithm or a cluster‐number decision algorithm to obtain optimal threshold values of each colour channel for a colour‐of‐interest. In this paper, a novel unsupervised multi‐threshold searching algorithm is proposed to automatically search the optimal threshold values for segmenting multiple colour objects. To achieve this, a novel ratio‐map image computation method is proposed to efficiently enhance the contrast between colour and non¬colour pixels. The Otsu’s method is then applied to the ratio‐map image to extract all colour objects from the image. Finally, a new histogram‐based multi‐threshold searching algorithm is developed to search the optimal upper‐bound and lower‐bound threshold values of hue, saturation and brightness components for each colour object. Experimental results show that the proposed method not only succeeds in separating all colour objects-of-interest in colour images, but also provides satisfactory colour thresholding results compared with an existing multilevel thresholding method.[[notice]]補正完畢[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]電子版[[booktype]]紙
Magnetic Anisotropy Variations and Non-Equilibrium Tunneling in a Cobalt Nanoparticle
We present detailed measurements of the discrete electron-tunneling level
spectrum within nanometer-scale cobalt particles as a function of magnetic
field and gate voltage, in this way probing individual quantum many-body
eigenstates inside ferromagnetic samples. Variations among the observed levels
indicate that different quantum states within one particle are subject to
different magnetic anisotropy energies. Gate-voltage studies demonstrate that
the low-energy tunneling spectrum is affected dramatically by the presence of
non-equilibrium spin excitations
Hydrogen peroxide and lime based oxidative pretreatment of wood waste to enhance enzymatic hydrolysis for a biorefinery: Process parameters optimization using response surface methodology
Response surface methodology (RSM) was adopted for the optimization of process variables in the alkaline
peroxide oxidation (APO) pretreatment of Vitellaria paradoxa sawdust based on central composite
design (CCD) experiments. A 23 five level CCD with central and axial points was used to develop a statistical
model for the optimization of process variables. Maximum response for the pretreatment was
obtained when applying the optimum values for temperature (150 �C), time (45 min), and 1% (v/v)
H2O2. At the optimum conditions, up to 70% of the initial hemicellulose was removed in treatments,
which also caused some delignification (up to 11% of the initial lignin was removed), whereas cellulose
was almost quantitatively retained in the solid phase. Alkaline peroxide assisted wet air oxidation (APAWAO)
pretreatment at the optimum conditions resulted in enrichment up to 60% cellulose content along
with solubilization of 80% hemicellulose and 17% of lignin initially present in the raw sawdust. Reducing
sugars yield after 72 h enzymatic hydrolysis of pretreated biomass at optimized APO conditions was
177.89 mg equivalent glucose g�1 dry biomass. Addition of 10 bar air pressure at the optimized pretreatment
conditions increased the sugars yield to 263.49 mg equivalent glucose g�1 dry biomass
Rare earth exchanged HY zeolite, an efficient catalyst for the synthesis of N-monosubstituted amides
369-37
Solving rate equations for electron tunneling via discrete quantum states
We consider the form of the current-voltage curves generated when tunneling
spectroscopy is used to measure the energies of individual electronic energy
levels in nanometer-scale systems. We point out that the voltage positions of
the tunneling resonances can undergo temperature-dependent shifts, leading to
errors in spectroscopic measurements that are proportional to temperature. We
do this by solving the set of rate equations that can be used to describe
electron tunneling via discrete quantum states, for a number of cases important
for comparison to experiments, including (1) when just one spin-degenerate
level is accessible for transport, (2) when 2 spin-degenerate levels are
accessible, with no variation in electron-electron interactions between
eigenstates, and (3) when 2 spin-degenerate levels are accessible, but with
variations in electron-electron interactions. We also comment on the general
case with an arbitrary number of accessible levels. In each case we analyze the
voltage-positions, amplitudes, and widths of the current steps due to the
quantum states.Comment: REVTeX 4, 10 pages, 12 figures, submitted to Phys. Rev. B. Associated
programs available at http://www.ccmr.cornell.edu/~ralph
Relativistic effects in photoionization time delay near the Cooper minimum of noble-gas atoms
Time delay of photoemission from valence ns, np3/2, and np1/2 subshells of noble-gas atoms is theoretically scrutinized within the framework of the dipole relativistic random phase approximation. The focus is on the variation of time delay in the vicinity of the Cooper minima in photoionization of the outer subshells of neon, argon, krypton, and xenon, where the corresponding dipole matrix element changes its sign while passing through a node. It is revealed that the presence of the Cooper minimum in one photoionization channel has a strong effect on time delay in other channels. This is shown to be due to interchannel coupling
Tunneling Via Individual Electronic States in Ferromagnetic Nanoparticles
We measure electron tunneling via discrete energy levels in ferromagnetic
cobalt particles less than 4 nm in diameter, using non-magnetic electrodes. Due
to magnetic anisotropy, the energy of each tunneling resonance shifts as an
applied magnetic field rotates the particle's magnetic moment. We see both
spin-increasing and decreasing tunneling transitions, but we do not observe the
spin degeneracy at small magnetic fields seen previously in non-magnetic
materials. The tunneling spectrum is denser than predicted for independent
electrons, possibly due to spin-wave excitations.Comment: 4 pages, 4 figures. Improved by comments from referees, to appear in
Phys. Rev. Let
- …