443 research outputs found
Tin Sulfide (SnS) Films Deposited by an Electric Field-Assisted Continuous Spray Pyrolysis Technique with Application as Counter Electrodes in Dye-Sensitized Solar Cells
The deposition of tin sulfide (SnS) nanostructured films using a continuous spray pyrolysis technique is reported with an electric field present at the nozzle for influencing the
atomization and the subsequent film deposition. In the absence of the electric field, the X-ray diffraction pattern shows the orthorhombic phase of SnS with a crystallographic preferred orientation along the (040) plane. The application of the electric field results in significant improvement in the morphology and a reduction in surface roughness (28 nm from 37 nm). The direct optical band gap of the films deposited with and without the electric field is estimated to be 1.5 and 1.7 eV, respectively. The photothermal deflection spectroscopy studies show a lower energetic disorder (no Urbach tail), which indicates an annealing effect in the SnS films deposited under the electric field. The improvement in the film properties is reflected in the expected improvement in the power conversion efficiency (PCE) of dye-sensitized solar cells fabricated using the SnS film as a counter electrode. An enhancement of PCE from 2.07% for the film deposited without the electric field to 2.89% for the film deposited with the electric field shows the role of the
electric field in the fabrication of improved SnS film
Spray deposited copper zinc tin sulphide (Cu<inf>2</inf>ZnSnS<inf>4</inf>) film as a counter electrode in dye sensitized solar cells
Stoichiometric thin films of Cu2ZnSnS4 (CZTS) were deposited by the spray technique on a FTO coated glass substrate, with post-annealing in a H2S environment to improve the film properties. CZTS films were used as a counter electrode (CE) in Dye-Sensitized Solar Cells (DSCs) with N719 dye and an iodine electrolyte. The DSC of 0.25 cm2 area using a CE of CZTS film annealed in a H2S environment under AM 1.5G illumination (100 mW cm-2) exhibited a short circuit current density (JSC) = 18.63 mA cm-2, an open circuit voltage (VOC) = 0.65 V and a fill factor (FF) = 0.53, resulting in an overall power conversion efficiency (PCE) = 6.4%. While the DSC using as deposited CZTS film as a CE showed the PCE = 3.7% with JSC = 13.38 mA cm-2, VOC = 0.57 V and FF = 0.48. Thus, the spray deposited CZTS films can play an important role as a CE in the large area DSC fabrication. © the Partner Organisations 2014
Governing culture: legislators, interpreters and accountants
Cultural policy has become dominated by questions of how to account for the intangible value of government investments. This is as a result of longstanding developments within government’s approaches to policy making, most notably those influenced by practices of audit and accounting. This paper will outline these developments with reference to Peter Miller’s concept of calculative practices, and will argue two central points: first, that there are practical solutions to the problem of measuring the value of culture that connect central government discourses with the discourses of the cultural sector; and second, the paper will demonstrate how academic work has been central to this area of policy making. As a result of the centrality of accounting academics in cultural policy, for example in providing advice on the appropriate measurement tools and techniques, questions are raised about the role academia might take vis-à-vis public policy. Accounting professionals and academics not only provide technical expertise that informs state calculative practices, but also play a surveillance role through the audit and evaluation of government programmes, and act as interpreters in defining terms of performance measurement, success and failure. The paper therefore concludes by reflecting on recent work by Phillip Schlesinger to preserve academic integrity whilst allowing accounting scholars and academics influence and partnership in policy
Cosmological Evolution Across Phantom Crossing and the Nature of the Horizon
In standard cosmology, with the evolution of the universe, the matter density
and thermodynamic pressure gradually decreases. Also in course of evolution,
the matter in the universe obeys (or violates) some restrictions or energy
conditions. If the matter distribution obeys strong energy condition (SEC), the
universe is in a decelerating phase while violation of SEC indicates an
accelerated expansion of the universe. In the period of accelerated expansion
the matter may be either of quintessence nature or of phantom nature depending
on the fulfilment of the weak energy condition (WEC) or violation of it. As
recent observational evidences demand that the universe is going through an
accelerated expansion so mater should be either quintessence or phantom in
nature. In the present work we study the evolution of the universe through the
phantom barrier (i.e. the dividing line between the quintessence and phantom
era) and examine how apparent and event horizon change across the barrier.
Finally, we investigate the possibility of occurrence of any singularity in
phantom era.Comment: 7 pages and 4 figure
Study of Thermodynamics in Generalized Holographic and Ricci Dark Energy Models
We have considered the flat FRW model of the universe which is filled with
the combination of dark matter and dark energy. Here we have considered two
types of dark energy models: (i) Generalized holographic and (ii) generalized
Ricci dark energies. The general descriptions of first law and generalized
second law (GSL) of thermodynamics have studied on the apparent horizon,
particle horizon and event horizon of the universe. We have shown that the
first law and GSL are always valid on apparent horizon and first law can not be
satisfied on the particle and event horizons in Einstein's gravity. These
results are always true for any types of dark energy models i.e., these results
do not depend on the dark energy models in Einstein's gravity. But the GSL
completely depends on the choices of dark energy models in Einstein's gravity.
Here we have discussed the validity of GSL in Generalized holographic and
generalized Ricci dark energy models. On the particle horizon GSL may be
satisfied but on the event horizon the GSL can not be satisfied for both the
dark energy models. Also we have considered the Generalized holographic dark
energy and generalized Ricci dark energy as the original holographic dark
energy, so in this situation we have calculated the expression of the radius of
the horizon . On this horizon, we have shown that the first law can not be
satisfied. Finally, on the horizon of radius , we have found that the GSL
can not be satisfied for both the dark energy models.Comment: 11 pages, 3 figure
Pion, kaon, proton and anti-proton transverse momentum distributions from p+p and d+Au collisions at GeV
Identified mid-rapidity particle spectra of , , and
from 200 GeV p+p and d+Au collisions are reported. A
time-of-flight detector based on multi-gap resistive plate chamber technology
is used for particle identification. The particle-species dependence of the
Cronin effect is observed to be significantly smaller than that at lower
energies. The ratio of the nuclear modification factor () between
protons and charged hadrons () in the transverse momentum
range GeV/c is measured to be
(stat)(syst) in minimum-bias collisions and shows little
centrality dependence. The yield ratio of in minimum-bias d+Au
collisions is found to be a factor of 2 lower than that in Au+Au collisions,
indicating that the Cronin effect alone is not enough to account for the
relative baryon enhancement observed in heavy ion collisions at RHIC.Comment: 6 pages, 4 figures, 1 table. We extended the pion spectra from
transverse momentum 1.8 GeV/c to 3. GeV/
Azimuthal anisotropy and correlations in p+p, d+Au and Au+Au collisions at 200 GeV
We present the first measurement of directed flow () at RHIC. is
found to be consistent with zero at pseudorapidities from -1.2 to 1.2,
then rises to the level of a couple of percent over the range . The latter observation is similar to data from NA49 if the SPS rapidities
are shifted by the difference in beam rapidity between RHIC and SPS.
Back-to-back jets emitted out-of-plane are found to be suppressed more if
compared to those emitted in-plane, which is consistent with {\it jet
quenching}. Using the scalar product method, we systematically compared
azimuthal correlations from p+p, d+Au and Au+Au collisions. Flow and non-flow
from these three different collision systems are discussed.Comment: Quark Matter 2004 proceeding, 4 pages, 3 figure
Azimuthal anisotropy: the higher harmonics
We report the first observations of the fourth harmonic (v_4) in the
azimuthal distribution of particles at RHIC. The measurement was done taking
advantage of the large elliptic flow generated at RHIC. The integrated v_4 is
about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8)
harmonics upper limits on the magnitudes are reported.Comment: 4 pages, 6 figures, contribution to the Quark Matter 2004 proceeding
Partonic flow and -meson production in Au+Au collisions at = 200 GeV
We present first measurements of the -meson elliptic flow
() and high statistics distributions for different
centralities from = 200 GeV Au+Au collisions at RHIC. In
minimum bias collisions the of the meson is consistent with the
trend observed for mesons. The ratio of the yields of the to those of
the as a function of transverse momentum is consistent with a model
based on the recombination of thermal quarks up to GeV/,
but disagrees at higher momenta. The nuclear modification factor () of
follows the trend observed in the mesons rather than in
baryons, supporting baryon-meson scaling. Since -mesons are
made via coalescence of seemingly thermalized quarks in central Au+Au
collisions, the observations imply hot and dense matter with partonic
collectivity has been formed at RHIC.Comment: 6 pages, 4 figures, submit to PR
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