1,665 research outputs found
Environmental Liquid Effluents, A Novel Approach For Treatment Of Industrial Waste Water
Nutrient enrichment or eutrophication of aquatic ecosystems can cause an increase in algae and aquatic
plants, loss of component species, and loss of ecosystem function. For these reasons, numerous studies
were focused on nitrogen and phosphorus removal from wastewater streams. Most of these studies were
based on biological processes and different combinations of anaerobic, aerobic, and anoxic zones such
as Bardenpho, A2O, UCT, and their modifications. Hence phosphate recovery from sewage is in synergy
with reducing other environmental impacts and making it a long term economic resource. The aim of the
novel treatment process is to highlight on studies investigated for the nutrient removal performance using
Chorella-vulgaris at different nitrogen and phosphorus concentrations. The effect of ammonia nitrogen
and phosphorus concentration on removal of these nutrients from synthetic wastewater by algae
Chorella-vulgaris in batch cultivation have been investigated in this study and kinetic coefficients were
determined. It is observed that an effluent may contain specific nutrients valuable for recovery and this
observation may lead to the idea or understanding of treating an effluent from industrial source as a
useful resource instead of the general idea of treating the effluent as waste products, and in the same
process losing money in terms of expenses on chemicals and energy. Treatment and discharge of
effluents into the receiving streams should not be an issue that will be considered as usual because there
are specified standards required by the legislation, in terms of the quality and characteristic of the effluent
before it is discharged into the waterways
On the Number of Solutions of Exponential Congruences
For a prime and an integer we obtain nontrivial upper bounds
on the number of solutions to the congruence , . We use these estimates to estimate the number of solutions to the
congruence , , which is of
cryptographic relevance
Transport in the XX chain at zero temperature: Emergence of flat magnetization profiles
We study the connection between magnetization transport and magnetization
profiles in zero-temperature XX chains. The time evolution of the transverse
magnetization, m(x,t), is calculated using an inhomogeneous initial state that
is the ground state at fixed magnetization but with m reversed from -m_0 for
x0. In the long-time limit, the magnetization evolves into a
scaling form m(x,t)=P(x/t) and the profile develops a flat part (m=P=0) in the
|x/t|1/2 while it
expands with the maximum velocity, c_0=1, for m_0->0. The states emerging in
the scaling limit are compared to those of a homogeneous system where the same
magnetization current is driven by a bulk field, and we find that the
expectation values of various quantities (energy, occupation number in the
fermionic representation) agree in the two systems.Comment: RevTex, 8 pages, 3 ps figure
Magnetization distribution in the transverse Ising chain with energy flux
The zero-temperature transverse Ising chain carrying an energy flux j_E is
studied with the aim of determining the nonequilibrium distribution functions,
P(M_z) and P(M_x), of its transverse and longitudinal magnetizations,
respectively. An exact calculation reveals that P(M_z) is a Gaussian both at
j_E=0 and j_E not equal 0, and the width of the distribution decreases with
increasing energy flux. The distribution of the order-parameter fluctuations,
P(M_x), is evaluated numerically for spin-chains of up to 20 spins. For the
equilibrium case (j_E=0), we find the expected Gaussian fluctuations away from
the critical point while the critical order-parameter fluctuations are shown to
be non-gaussian with a scaling function Phi(x)=Phi(M_x/)=P(M_x)
strongly dependent on the boundary conditions. When j_E not equal 0, the system
displays long-range, oscillating correlations but P(M_x) is a Gaussian
nevertheless, and the width of the Gaussian decreases with increasing j_E. In
particular, we find that, at critical transverse field, the width has a
j_E^(-3/8) asymptotic in the j_E -> 0 limit.Comment: 8 pages, 5 ps figure
Formation of Liesegang patterns: Simulations using a kinetic Ising model
A kinetic Ising model description of Liesegang phenomena is studied using
Monte Carlo simulations. The model takes into account thermal fluctuations,
contains noise in the chemical reactions, and its control parameters are
experimentally accessible. We find that noisy, irregular precipitation takes
place in dimension d=2 while, depending on the values of the control
parameters, either irregular patterns or precipitation bands satisfying the
regular spacing law emerge in d=3.Comment: 7 pages, 8 ps figures, RevTe
AdS_4/CFT_3 Construction from Collective Fields
We pursue the construction of higher-spin theory in AdS_4 from CFT_3 of the
O(N) vector model in terms of canonical collective fields. In null plane
quantization an exact map is established between the two spaces. The
coordinates of the AdS_4 space-time are generated from the collective
coordinates of the bi-local field. This, in the light cone gauge, provides an
exact one to one reconstruction of bulk AdS_4 space-time and higher-spin
fields.Comment: 17 pages, no figures; v2: references added; v3: minor change
Matrix Model Maps and Reconstruction of AdS SUGRA Interactions
We consider the question of reconstructing (cubic) SUGRA interactions in
AdS/CFT. The method we introduce is based on the matrix model maps (MMP) which
were previously successfully employed at the linearized level. The strategy is
to start with the map for 1/2 BPS configurations which is exactly known (to all
orders) in the hamiltonian framework. We then use the extension of the matrix
model map with the corresponding Ward identities to completely specify the
interaction. A central point in this construction is the non-vanishing of
off-shell interactions (even for highest-weight states).Comment: 28 page
Non-Gaussian Resistance Noise near Electrical Breakdown in Granular Materials
The distribution of resistance fluctuations of conducting thin films with
granular structure near electrical breakdown is studied by numerical
simulations. The film is modeled as a resistor network in a steady state
determined by the competition between two biased processes, breaking and
recovery. Systems of different sizes and with different levels of internal
disorder are considered. Sharp deviations from a Gaussian distribution are
found near breakdown and the effect increases with the degree of internal
disorder. However, we show that in general this non-Gaussianity is related to
the finite size of the system and vanishes in the large size limit.
Nevertheless, near the critical point of the conductor-insulator transition,
deviations from Gaussianity persist when the size is increased and the
distribution of resistance fluctuations is well fitted by the universal
Bramwell-Holdsworth-Pinton distribution.Comment: 8 pages, 6 figures; accepted for publication on Physica
Probability distribution of magnetization in the one-dimensional Ising model: Effects of boundary conditions
Finite-size scaling functions are investigated both for the mean-square
magnetization fluctuations and for the probability distribution of the
magnetization in the one-dimensional Ising model. The scaling functions are
evaluated in the limit of the temperature going to zero (T -> 0), the size of
the system going to infinity (N -> oo) while N[1-tanh(J/k_BT)] is kept finite
(J being the nearest neighbor coupling). Exact calculations using various
boundary conditions (periodic, antiperiodic, free, block) demonstrate
explicitly how the scaling functions depend on the boundary conditions. We also
show that the block (small part of a large system) magnetization distribution
results are identical to those obtained for free boundary conditions.Comment: 8 pages, 5 figure
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