Recloser based energy exposure assessment of a distribution network

The optimised placement of reclosers on a distribution network is known to improve the reliability of a power system. Furthermore, the protection settings on distribution systems rely heavily on the number and placement of such reclosers. This study examined the effect of using protection settings methodology with the placement of reclosers to ameliorate the damage sustained during faults on a distribution network. The aim of the study was to determine whether this ‘damage control factor’ should be a future consideration for recloser placement. It has been found that the determination of the number and placement of reclosers, which are the function of the energy exposure of feeder, helped to optimise the operation and reliability of a distribution network. This could benefit both energy users and energy suppliers, who often face different challenges during the fault levels on the network

Non-Abelian (p,q) Strings in the Warped Deformed Conifold

We calculate the tension of $(p,q)$-strings in the warped deformed conifold using the non-Abelian DBI action. In the large flux limit, we find exact agreement with the recent expression obtained by Firouzjahi, Leblond and Henry-Tye up to and including order $1/M^2$ terms if $q$ is also taken to be large. Furthermore using the finite $q$ prescription for the symmetrised trace operation we anticipate the most general expression for the tension valid for any $(p,q)$. We find that even in this instance, corrections to the tension scale as $1/M^2$ which is not consistent with simple Casimir scaling.Comment: 18 pages, Latex, 1 figure; Added a discussion of the case when the warp factor parameter $b\neq 1$ and typos correcte

Improving the identification of hydrologically sensitive areas using LiDAR DEMs for the delineation and mitigation of critical source areas of diffuse pollution

AbstractIdentifying critical source areas (CSAs) of diffuse pollution in agricultural catchments requires the accurate identification of hydrologically sensitive areas (HSAs) at highest propensity for generating surface runoff and transporting pollutants. A new GIS-based HSA Index is presented that improves the identification of HSAs at the sub-field scale by accounting for microtopographic controls. The Index is based on high resolution LiDAR data and a soil topographic index (STI) and also considers the hydrological disconnection of overland flow via topographic impediment from flow sinks. The HSA Index was applied to four intensive agricultural catchments (~7.5–12km2) with contrasting topography and soil types, and validated using rainfall-quickflow measurements during saturated winter storm events in 2009–2014. Total flow sink volume capacities ranged from 8298 to 59,584m3 and caused 8.5–24.2% of overland-flow-generating-areas and 16.8–33.4% of catchment areas to become hydrologically disconnected from the open drainage channel network. HSA maps identified ‘breakthrough points’ and ‘delivery points’ along surface runoff pathways as vulnerable points where diffuse pollutants could be transported between fields or delivered to the open drainage network, respectively. Using these as proposed locations for targeting mitigation measures such as riparian buffer strips reduced potential costs compared to blanket implementation within an example agri-environment scheme by 66% and 91% over 1 and 5years respectively, which included LiDAR DEM acquisition costs. The HSA Index can be used as a hydrologically realistic transport component within a fully evolved sub-field scale CSA model, and can also be used to guide the implementation of ‘treatment-train’ mitigation strategies concurrent with sustainable agricultural intensification

Global QCD analysis and dark photons

Published: September 15, 2023We perform a global QCD analysis of high energy scattering data within the JAM Monte Carlo framework, including a coupling to a dark photon that augments the Standard Model (SM) electroweak coupling via kinetic mixing with the hypercharge B boson. We first set limits on the dark photon mass and mixing parameter assuming that the SM is the true theory of Nature, taking into account also the effect on g – 2 of the muon. If instead we entertain the possibility that the dark photon may play a role in deep-inelastic scattering (DIS), we find that the best fit is preferred over the SM at 6.5σ, even after accounting for missing higher order uncertainties. The improvement in χ² with the dark photon is stable against all the tests we have applied, with the improvements in the theoretical predictions spread across a wide range of x and Q². The largest improvement corresponds to the fixed target and HERA DIS data, while the best fit yields a value of g – 2 which significantly reduces the disagreement with the latest experimental determination.N. T. Hunt-Smith, a W. Melnitchouk, a, b N. Sato, b A. W. Thomas, a X. G. Wanga and M. J. Whitea on behalf of the Jefferson Lab Angular Momentum (JAM) collaboratio

Inflation with improved D3-brane potential and the fine tunings associated with the model

We investigate brane-antibrane inflation in a warped deformed conifold background that includes contributions to the potential arising from imaginary anti-self-dual (IASD) fluxes including the term with irrational scaling dimension discovered recently. We find that the model can give rise to required number of e-foldings; observational constraint on COBE normalization is easily satisfied and low value of the tensor to scalar ratio of perturbations is achieved. We observe that these corrections to the effective potential help in relaxing the severe fine tunings associated with the earlier analysis.Comment: 8 pages, 4 figures; typos corrected, minor clarifications and new refs added, to appear in epj

Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model

The physics of a two-component cold fermi gas is now frequently addressed in laboratories. Usually this is done for large samples of tens to hundreds of thousands of particles. However, it is now possible to produce few-body systems (1-100 particles) in very tight traps where the shell structure of the external potential becomes important. A system of two-species fermionic cold atoms with an attractive zero-range interaction is analogous to a simple model of nucleus in which neutrons and protons interact only through a residual pairing interaction. In this article, we discuss how the problem of a two-component atomic fermi gas in a tight external trap can be mapped to the nuclear shell model so that readily available many-body techniques in nuclear physics, such as the Shell Model Monte Carlo (SMMC) method, can be directly applied to the study of these systems. We demonstrate an application of the SMMC method by estimating the pairing correlations in a small two-component Fermi system with moderate-to-strong short-range two-body interactions in a three-dimensional harmonic external trapping potential.Comment: 13 pages, 3 figures. Final versio

Improved numerical stability of stationary black hole evolution calculations

We experiment with modifications of the BSSN form of the Einstein field equations (a reformulation of the ADM equations) and demonstrate how these modifications affect the stability of numerical black hole evolution calculations. We use excision to evolve both non-rotating and rotating Kerr-Schild black holes in octant and equatorial symmetry, and without any symmetry assumptions, and obtain accurate and stable simulations for specific angular momenta J/M of up to about 0.9M.Comment: 13 pages, 11 figures, 1 typo in Eq. (20) correcte

Dust Devil Tracks

Dust devils that leave dark- or light-toned tracks are common on Mars and they can also be found on the Earth’s surface. Dust devil tracks (hereinafter DDTs) are ephemeral surface features with mostly sub-annual lifetimes. Regarding their size, DDT widths can range between ∼1 m and ∼1 km, depending on the diameter of dust devil that created the track, and DDT lengths range from a few tens of meters to several kilometers, limited by the duration and horizontal ground speed of dust devils. DDTs can be classified into three main types based on their morphology and albedo in contrast to their surroundings; all are found on both planets: (a) dark continuous DDTs, (b) dark cycloidal DDTs, and (c) bright DDTs. Dark continuous DDTs are the most common type on Mars. They are characterized by their relatively homogenous and continuous low albedo surface tracks. Based on terrestrial and martian in situ studies, these DDTs most likely form when surficial dust layers are removed to expose larger-grained substrate material (coarse sands of ≥500 μm in diameter). The exposure of larger-grained materials changes the photometric properties of the surface; hence leading to lower albedo tracks because grain size is photometrically inversely proportional to the surface reflectance. However, although not observed so far, compositional differences (i.e., color differences) might also lead to albedo contrasts when dust is removed to expose substrate materials with mineralogical differences. For dark continuous DDTs, albedo drop measurements are around 2.5 % in the wavelength range of 550–850 nm on Mars and around 0.5 % in the wavelength range from 300–1100 nm on Earth. The removal of an equivalent layer thickness around 1 μm is sufficient for the formation of visible dark continuous DDTs on Mars and Earth. The next type of DDTs, dark cycloidal DDTs, are characterized by their low albedo pattern of overlapping scallops. Terrestrial in situ studies imply that they are formed when sand-sized material that is eroded from the outer vortex area of a dust devil is redeposited in annular patterns in the central vortex region. This type of DDT can also be found in on Mars in orbital image data, and although in situ studies are lacking, terrestrial analog studies, laboratory work, and numerical modeling suggest they have the same formation mechanism as those on Earth. Finally, bright DDTs are characterized by their continuous track pattern and high albedo compared to their undisturbed surroundings. They are found on both planets, but to date they have only been analyzed in situ on Earth. Here, the destruction of aggregates of dust, silt and sand by dust devils leads to smooth surfaces in contrast to the undisturbed rough surfaces surrounding the track. The resulting change in photometric properties occurs because the smoother surfaces have a higher reflectance compared to the surrounding rough surface, leading to bright DDTs. On Mars, the destruction of surficial dust-aggregates may also lead to bright DDTs. However, higher reflective surfaces may be produced by other formation mechanisms, such as dust compaction by passing dust devils, as this may also cause changes in photometric properties. On Mars, DDTs in general are found at all elevations and on a global scale, except on the permanent polar caps. DDT maximum areal densities occur during spring and summer in both hemispheres produced by an increase in dust devil activity caused by maximum insolation. Regionally, dust devil densities vary spatially likely controlled by changes in dust cover thicknesses and substrate materials. This variability makes it difficult to infer dust devil activity from DDT frequencies. Furthermore, only a fraction of dust devils leave tracks. However, DDTs can be used as proxies for dust devil lifetimes and wind directions and speeds, and they can also be used to predict lander or rover solar panel clearing events. Overall, the high DDT frequency in many areas on Mars leads to drastic albedo changes that affect large-scale weather patterns

Association of community engagement with vaccination confidence and uptake: A cross-sectional survey in Sierra Leone, 2019

Background The 2014-2016 Ebola epidemic disrupted childhood immunization in Sierra Leone, Liberia, and Guinea. After the epidemic, the Government of Sierra Leone prioritized community engagement to increase vaccination confidence and uptake. To support these efforts, we examined potential drivers of vaccination confidence and uptake in Sierra Leone. Methods We conducted a population-based household survey with primary caregivers of children in a birth cohort of 12 to 23 months in four districts with low vaccination coverage in Sierra Leone in 2019. Modified Poisson regression modeling with robust variance estimation was used to examine if perceived community engagement in planning the immunization program in the community was associated with vaccination confidence and having a fully vaccinated child. Results The sample comprised 621 age-eligible children and their caregivers (91% response rate). Half of the caregivers (52%) reported that it usually takes too long to get to the vaccination site, and 36% perceived that health workers expect money for vaccination services that are supposed to be given at no charge. When mothers were the decision-makers of the children’s vaccination, 80% of the children were fully vaccinated versus 69% when fathers were the decision-makers and 56% when other relatives were the decision-makers. Caregivers with high confidence in vaccination were more likely to have fully vaccinated children compared to caregivers with low confidence (78% versus 53%). For example, caregivers who thought vaccines are ‘very much’ safe were more likely to have fully vaccinated children than those who thought vaccines are ‘somewhat’ safe (76% versus 48%). Overall, 53% of caregivers perceived high level of community engagement, 41% perceived medium level of engagement, and 6% perceived low level of engagement. Perceiving high community engagement was associated with expressing high vaccination confidence (adjusted prevalence ratio (aPR) = 2.60; 95% confidence interval (CI) = 1.67-4.04) and having a fully vaccinated child (aPR = 1.67; 95% CI = 1.18-2.38). Conclusions In these four low coverage districts in Sierra Leone, the perceived level of community engagement was strongly associated with vaccination confidence among caregivers and vaccination uptake among children. We have provided exploratory cross-sectional evidence to inform future longitudinal assessments to further investigate the potential causal effect of community engagement on vaccination confidence and uptake

Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter

Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{$6\times 10^{19}$eV}. The anisotropy was measured by the fraction of arrival directions that are less than $3.1^\circ$ from the position of an active galactic nucleus within 75 Mpc (using the V\'eron-Cetty and V\'eron $12^{\rm th}$ catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is $(38^{+7}_{-6})$, compared with $21$ expected for isotropic cosmic rays. This is down from the early estimate of $(69^{+11}_{-13})$. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201