1,021 research outputs found
Integrated simulation and optimisation of hybrid photovoltaic-thermal (PV-T) and photovoltaic systems for decentralised rural hot water provision and electrification
Demands for electricity and hot water continue to rise worldwide, with many people in low-income countries, especially in rural areas, lacking access to these basic services. Decentralised minigrids, capable of powering small off-grid communities, are increasingly used in low-income countries as a means of providing power to the 13% of people globally without access to electricity. Hybrid solar photovoltaic-thermal (PV-T) collectors combine both photovoltaic (PV) cell and solar-thermal absorbers and, therefore, output both electricity and heat from a single collector with efficiency benefits over standalone PV panels and solar-thermal collectors. Despite this, no models have yet been developed capable of assessing the performance of PV-T collectors generalisable across a range of off-grid settings. We present an integrated model for simulating and optimising combined systems comprising PV panels and PV-T collectors, accurate to within +/- 5% rms error, connected to wider electrical and hot water systems, and employ this to evaluate their potential to meet both electrical and hot-water demands of rural communities. We provide a tool for simulating the lifetime output from combined PV and PV-T systems, assessing their economic and environmental impact, and for optimising the systems to meet the needs of specific communities. We carry out simulations for a case study of a combined PV and PV-T system in Uttar Pradesh, India, and find that the system is able to meet 59.3% and 33.5% of hot water demand for upper and lower bounds for installed capacity. We carry out optimisations for static high demand and growing low-demand scenarios and find that that 35 kWpel and 5 hot-water tanks and 75 kWpel and 15 hot-water tanks are needed to meet these demand scenarios respectively
Particle Size Distribution and Human Respiratory Deposition of Trace Metals in Indoor Work Environments
Respiratory response to inhalation of fine particles has been investigated for the aerosol generated by welding. Particles were sampled using a pair of 5-stage cascade impactors operating at 1 l./min flow rate. The subject exhaled into one impactor through an air ballast arrangement, and the other impactor simultaneously sampled the surrounding air. Particle size fractions were analyzed for principal elemental constituents from sulphur to lead using proton induced X-ray emission, PIXE. The results indicated a complex respiratory response, including both increase in particle size due to exposure to high humidity in the respiratory tract and deposition of particles during inhalation. The response was found to be different for the element group Mn, Cr, Fe, Ni compared to the group K, Ca, Ti by observing the associations among the elements as a function of particle size in the inhaled and exhaled aerosol. However, for respiratory deposition efficiency alone in all runs averaged together, no systematic differences between the different elements are demonstrated at the 99 % confidence level
Thermal excitation of heavy nuclei with 5-15 GeV/c antiproton, proton and pion beams
Excitation-energy distributions have been derived from measurements of
5.0-14.6 GeV/c antiproton, proton and pion reactions with Au target
nuclei, using the ISiS 4 detector array. The maximum probability for
producing high excitation-energy events is found for the antiproton beam
relative to other hadrons, He and beams from LEAR. For protons
and pions, the excitation-energy distributions are nearly independent of hadron
type and beam momentum above about 8 GeV/c. The excitation energy enhancement
for beams and the saturation effect are qualitatively consistent with
intranuclear cascade code predictions. For all systems studied, maximum cluster
sizes are observed for residues with E*/A 6 MeV.Comment: 14 pages including 5 figures and 1 table. Accepted in Physics Letter
B. also available at http://nuchem.iucf.indiana.edu
KIR-HLA and Maternal-Infant HIV-1 Transmission in Sub-Saharan Africa
Numerous studies have suggested a role for natural killer (NK) cells in attenuation of HIV-1 disease progression via recognition by killer-cell immunoglobulin-like receptors (KIRs) of specific HLA class I molecules. The role of KIR and HLA class I has not been addressed in the context of maternal-infant HIV-1 transmission. KIR and HLA class I B and C genes from 224 HIV-1-infected mothers and 222 infants (72 infected and 150 uninfected) from South Africa were characterized. Although a number of significant associations were determined in both the total group and in the nevirapine (NVP) exposed group, the most significant findings involved KIR2DL2 and KIR2DL3 and HLA-C. KIR2DL2/KIR2DL3 was underrepresented in intrapartum (IP)-transmitting mothers compared to non-transmitting (NT) mothers (P = 0.008) and remained significant (P = 0.036) after correction for maternal viral load (MVL). Homozygosity for KIR2DL3 alone and in combination with HLA-C allotype heterozygosity (C1C2) was elevated in IP-transmitting mothers compared to NT mothers (P = 0.034 and P = 0.01 respectively), and after MVL correction (P = 0.033 and P = 0.027, respectively). In infants, KIR2DL3 in combination with its HLA-C1 ligand (C1) as well as homozygosity for KIR2DL3 with C1C2, were both found to be underrepresented in infected infants compared to exposed uninfected infants in the total group (P = 0.06 and P = 0.038, respectively) and in the sub-group of infants whose mothers received NVP (P = 0.007 and P = 0.03, respectively). These associations were stronger post MVL adjustment (total group: P = 0.02 and P = 0.009, respectively; NVP group: P = 0.004 and P = 0.02, respectively). Upon stratification according to low and high MVL, all significant associations fell within the low MVL group, suggesting that with low viral load, the effects of genotype can be more easily detected. In conclusion this study has identified a number of significant associations that suggest an important role for NK cells in maternal-to-infant HIV-1 transmission
KIR-HLA and Maternal-Infant HIV-1 Transmission in Sub-Saharan Africa
Numerous studies have suggested a role for natural killer (NK) cells in attenuation of HIV-1 disease progression via recognition by killer-cell immunoglobulin-like receptors (KIRs) of specific HLA class I molecules. The role of KIR and HLA class I has not been addressed in the context of maternal-infant HIV-1 transmission. KIR and HLA class I B and C genes from 224 HIV-1-infected mothers and 222 infants (72 infected and 150 uninfected) from South Africa were characterized. Although a number of significant associations were determined in both the total group and in the nevirapine (NVP) exposed group, the most significant findings involved KIR2DL2 and KIR2DL3 and HLA-C. KIR2DL2/KIR2DL3 was underrepresented in intrapartum (IP)-transmitting mothers compared to non-transmitting (NT) mothers (P = 0.008) and remained significant (P = 0.036) after correction for maternal viral load (MVL). Homozygosity for KIR2DL3 alone and in combination with HLA-C allotype heterozygosity (C1C2) was elevated in IP-transmitting mothers compared to NT mothers (P = 0.034 and P = 0.01 respectively), and after MVL correction (P = 0.033 and P = 0.027, respectively). In infants, KIR2DL3 in combination with its HLA-C1 ligand (C1) as well as homozygosity for KIR2DL3 with C1C2, were both found to be underrepresented in infected infants compared to exposed uninfected infants in the total group (P = 0.06 and P = 0.038, respectively) and in the sub-group of infants whose mothers received NVP (P = 0.007 and P = 0.03, respectively). These associations were stronger post MVL adjustment (total group: P = 0.02 and P = 0.009, respectively; NVP group: P = 0.004 and P = 0.02, respectively). Upon stratification according to low and high MVL, all significant associations fell within the low MVL group, suggesting that with low viral load, the effects of genotype can be more easily detected. In conclusion this study has identified a number of significant associations that suggest an important role for NK cells in maternal-to-infant HIV-1 transmission
Evidence of Critical Behavior in the Disassembly of Nuclei with A ~ 36
A wide variety of observables indicate that maximal fluctuations in the
disassembly of hot nuclei with A ~ 36 occur at an excitation energy of 5.6 +-
0.5 MeV/u and temperature of 8.3 +- 0.5 MeV. Associated with this point of
maximal fluctuations are a number of quantitative indicators of apparent
critical behavior. The associated caloric curve does not appear to show a
flattening such as that seen for heavier systems. This suggests that, in
contrast to similar signals seen for liquid-gas transitions in heavier nuclei,
the observed behavior in these very light nuclei is associated with a
transition much closer to the critical point.Comment: v2: Major changes, new model calculations, new figure
Critical Behavior in Light Nuclear Systems: Experimental Aspects
An extensive experimental survey of the features of the disassembly of a
small quasi-projectile system with 36, produced in the reactions of 47
MeV/nucleon Ar + Al, Ti and Ni, has been carried
out. Nuclei in the excitation energy range of 1-9 MeV/u have been investigated
employing a new method to reconstruct the quasi-projectile source. At an
excitation energy 5.6 MeV/nucleon many observables indicate the presence
of maximal fluctuations in the de-excitation processes. The fragment
topological structure shows that the rank sorted fragments obey Zipf's law at
the point of largest fluctuations providing another indication of a liquid gas
phase transition. The caloric curve for this system shows a monotonic increase
of temperature with excitation energy and no apparent plateau. The temperature
at the point of maximal fluctuations is MeV. Taking this
temperature as the critical temperature and employing the caloric curve
information we have extracted the critical exponents , and
from the data. Their values are also consistent with the values of the
universality class of the liquid gas phase transition. Taken together, this
body of evidence strongly suggests a phase change in an equilibrated mesoscopic
system at, or extremely close to, the critical point.Comment: Physical Review C, in press; some discussions about the validity of
excitation energy in peripheral collisions have been added; 24 pages and 32
figures; longer abstract in the preprin
Tracing the Evolution of Temperature in Near Fermi Energy Heavy Ion Collisions
The kinetic energy variation of emitted light clusters has been employed as a
clock to explore the time evolution of the temperature for thermalizing
composite systems produced in the reactions of 26A, 35A and 47A MeV Zn
with Ni, Mo and Au. For each system investigated, the
double isotope ratio temperature curve exhibits a high maximum apparent
temperature, in the range of 10-25 MeV, at high ejectile velocity. These
maximum values increase with increasing projectile energy and decrease with
increasing target mass. The time at which the maximum in the temperature curve
is reached ranges from 80 to 130 fm/c after contact. For each different target,
the subsequent cooling curves for all three projectile energies are quite
similar. Temperatures comparable to those of limiting temperature systematics
are reached 30 to 40 fm/c after the times corresponding to the maxima, at a
time when AMD-V transport model calculations predict entry into the final
evaporative or fragmentation stage of de-excitation of the hot composite
systems. Evidence for the establishment of thermal and chemical equilibrium is
discussed.Comment: 9 pages, 5 figure
- …