407 research outputs found
Study on Ultrasonic Degradation of Pentachlorophenol Solution
Pentachlorophenol (PCP) ion was degraded by ultrasound at 25 C. Four aspects that could affect the degradation of PCP were investigated, i.e. initial pH of solution, initial concentration of pentachlorophenol ion, different sound intensity with catalyst and different frequencies of ultrasound. Results showed that PCP ion could be ultrasonic degraded
totally after 3 hour treatment if CCl4, which can provide free radical, was added in solution. The mechanism of ultrasonic degradation was considered as free radical oxidation by adding n-butyl alcohol as free radical scavenger
Study on Ultrasonic Degradation of Pentachlorophenol Solution
Pentachlorophenol (PCP) ion was degraded by ultrasound at 25 C. Four aspects that could affect the degradation of PCP were investigated, i.e. initial pH of solution, initial concentration of pentachlorophenol ion, different sound intensity with catalyst and different frequencies of ultrasound. Results showed that PCP ion could be ultrasonic degraded
totally after 3 hour treatment if CCl4, which can provide free radical, was added in solution. The mechanism of ultrasonic degradation was considered as free radical oxidation by adding n-butyl alcohol as free radical scavenger
The effect of applied electric field on pulsed radio frequency and pulsed direct current plasma jet array
Here we compare the plasma plume propagation characteristics of a 3-channel pulsed RF plasma jet array and those of the same device operated by a pulsed dc source. For the pulsed-RF jet array, numerous long life time ions and metastables accumulated in the plasma channel make the plasma plume respond quickly to applied electric field. Its structure similar as “plasma bullet” is an anode glow indeed. For the pulsed dcplasma jet array, the strong electric field in the vicinity of the tube is the reason for the growing plasma bullet in the launching period. The repulsive forces between the growing plasma bullets result in the divergence of the pulsed dcplasma jet array. Finally, the comparison of 309 nm and 777 nm emissions between these two jet arrays suggests the high chemical activity of pulsed RF plasma jet array
Electrical transport and magnetic properties of nanostructured La0.67Ca0.33MnO3
Nanostructured La0.67Ca0.33MnO3 (NS-LCMO) was formed by pulsed-laser
deposition on the surface of porous Al2O3. The resistance peak temperature (Tp)
of the NS-LCMO increases with increasing average thickness of the films, while
their Curie temperatures (Tc) remain unchanged. The coercive field of the
samples increases with decreasing film thickness and its temperature dependence
can be well described by Hc(T) = Hc(0)[1-(T/TB)1/2]. A large magnetoresistance
and strong memory effect were observed for the NS-LCMO. The results are
discussed in terms of the size effect, Coulomb blockade and magnetic tunneling
effect. This work also demonstrates a new way to get nanostructured manganites
Basis Functions for Linear-Scaling First-Principles Calculations
In the framework of a recently reported linear-scaling method for
density-functional-pseudopotential calculations, we investigate the use of
localized basis functions for such work. We propose a basis set in which each
local orbital is represented in terms of an array of `blip functions'' on the
points of a grid. We analyze the relation between blip-function basis sets and
the plane-wave basis used in standard pseudopotential methods, derive criteria
for the approximate equivalence of the two, and describe practical tests of
these criteria. Techniques are presented for using blip-function basis sets in
linear-scaling calculations, and numerical tests of these techniques are
reported for Si crystal using both local and non-local pseudopotentials. We
find rapid convergence of the total energy to the values given by standard
plane-wave calculations as the radius of the linear-scaling localized orbitals
is increased.Comment: revtex file, with two encapsulated postscript figures, uses epsf.sty,
submitted to Phys. Rev.
Towards a Linear-Scaling DFT Technique: The Density Matrix Approach
A recently proposed linear-scaling scheme for density-functional
pseudopotential calculations is described in detail. The method is based on a
formulation of density functional theory in which the ground state energy is
determined by minimization with respect to the density matrix, subject to the
condition that the eigenvalues of the latter lie in the range [0,1].
Linear-scaling behavior is achieved by requiring that the density matrix should
vanish when the separation of its arguments exceeds a chosen cutoff. The
limitation on the eigenvalue range is imposed by the method of Li, Nunes and
Vanderbilt. The scheme is implemented by calculating all terms in the energy on
a uniform real-space grid, and minimization is performed using the
conjugate-gradient method. Tests on a 512-atom Si system show that the total
energy converges rapidly as the range of the density matrix is increased. A
discussion of the relation between the present method and other linear-scaling
methods is given, and some problems that still require solution are indicated.Comment: REVTeX file, 27 pages with 4 uuencoded postscript figure
A probabilistic method for the operation of three-phase unbalanced active distribution networks
YesThis paper proposes a probabilistic multi-objective optimization method for the operation of three-phase distribution networks incorporating active network management (ANM) schemes including coordinated voltage control and adaptive power factor control. The proposed probabilistic method incorporates detailed modelling of three-phase distribution network components and considers different operational objectives. The method simultaneously minimizes the total energy losses of the lines from the point of view of distribution network operators (DNOs) and maximizes the energy generated by photovoltaic (PV) cells considering ANM schemes and network constraints. Uncertainties related to intermittent generation of PVs and load demands are modelled by probability density functions (PDFs). Monte Carlo simulation method is employed to use the generated PDFs. The problem is solved using ɛ-constraint approach and fuzzy satisfying method is used to select the best solution from the Pareto optimal set. The effectiveness of the proposed probabilistic method is demonstrated with IEEE 13- and 34- bus test feeders
A Measurement of Psi(2S) Resonance Parameters
Cross sections for e+e- to hadons, pi+pi- J/Psi, and mu+mu- have been
measured in the vicinity of the Psi(2S) resonance using the BESII detector
operated at the BEPC. The Psi(2S) total width; partial widths to hadrons,
pi+pi- J/Psi, muons; and corresponding branching fractions have been determined
to be Gamma(total)= (264+-27) keV; Gamma(hadron)= (258+-26) keV, Gamma(mu)=
(2.44+-0.21) keV, and Gamma(pi+pi- J/Psi)= (85+-8.7) keV; and Br(hadron)=
(97.79+-0.15)%, Br(pi+pi- J/Psi)= (32+-1.4)%, Br(mu)= (0.93+-0.08)%,
respectively.Comment: 8 pages, 6 figure
Measurements of the Mass and Full-Width of the Meson
In a sample of 58 million events collected with the BES II detector,
the process J/ is observed in five different decay
channels: , , (with ), (with
) and . From a combined fit of all five
channels, we determine the mass and full-width of to be
MeV/ and
MeV/.Comment: 9 pages, 2 figures and 4 table. Submitted to Phys. Lett.
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