5,309 research outputs found
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Machine Learning on residential electricity consumption: Which households are more responsive to weather?
The introduction of smart meters has created opportunities for both utilities and policymakers to understand residential electricity consumption in greater depth. Machine learning techniques have distinct advantages over traditional approaches in dealing with extremely large volumes of high-resolution usage data. We introduce a novel clustering method to detect household behaviour using different types of weather data as proxies. Based on this approach, we combine Irish smart meter and weather data to identify and characterize clear differences in the daily patterns between workdays and weekends in both summer and winter and investigate how households respond to changing weather patterns. We also examine the relationships between response groups and household demographic features using different statistical tests. We find the magnitude of the effect of occupancy-related variables in the clustering of weather sensitivity to be larger than incomerelated factors. This proposed new approach could be the basis of a classification model to identify households that are more responsive to different types of weather. Tariff design could benefit from such a model and enable specific schemes to be developed that would target weather-sensitive households and result in improved load management
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Identifying residential consumption patterns using data-mining techniques: A large-scale study of smart meter data in Chengdu, China
The fine-grained electricity consumption data created by advanced metering technologies offers an opportunity to understand residential demand from new angles. Although there exists a large body of research on demand response in short- and long-term forecasting, a comprehensive analysis to identify household consumption behaviour in different scenarios has not been conducted. The study’s novelty lies in its use of unsupervised machine learning tools to explore residential customers’ demand patterns and response without the assistance of traditional survey tools. We investigate behavioural response in three different contexts: 1) seasonal (using weekly consumption profiles); 2) holidays/festivals; and 3) extreme weather situations. The analysis is based on the smart metering data of 2,000 households in Chengdu, China over three years from 2014 to 2016. Workday/weekend profiles indicate that there are two distinct groups of households that appear to be white-collar or relatively affluent families. Demand patterns at the major festivals in China, especially the Spring Festival, reveal various types of lifestyle and households. In terms of extreme weather response, the most striking finding was that in summer, at night-time, over 72% of households doubled (or more) their electricity usage, while consumption changes in winter do not seem to be significant. Our research offers more detailed insight into Chinese residential consumption and provides a practical framework to understand households’ behaviour patterns in different settings
Modeling of Jovian Hectometric Radiation Source Locations: Ulysses Observations
The Unified Radio and Plasma Wave (URAP) experiment on Ulysses has provided unique high latitude measurements of Jovian hectometric radiation (HOM) during its encounter with Jupiter in February 1992. URAP was the first radio instrument in the Jovian environment with radio direction-finding capability, which was previously used to determine the HOM source locations in the Jovian magnetosphere. These initial source location determinations were based on several assumptions, including the neglect of refractive effects, which may be tested. We have, for the first time, combined the measured incident ray-direction at the spacecraft with a model magnetosphere to directly trace the rays back to the HOM source. We concentrate on the observations of HOM from high northern latitudes when Ulysses was at distances less than 15 R(sub j). The three- dimensional ray-tracing calculations presented here indicate that the HOM sources probably lie on L shells in the range 3 less than or approximately equal to L less than 7 (tilted dipole magnetic field model) consistent with previous determinations that ignored the effects of refraction. The ray-tracing results, however, indicate that wave refraction due to the Io torus and the magnetic field can significantly influence the precise source location. We show that constraints on the locations imposed by the gyroemission mechanism suggest that the lo torus density may have experienced temporal and/or spatial fluctuations during the Ulysses observations of HOM. Finally, in the cold plasma approximation we demonstrate that even if the emission were nearly linearly polarized near the source region, almost circular polarization will be observed at Ulysses, in agreement with observations
Reflection factorizations of Singer cycles
Abstract. The number of shortest factorizations into reflections for a Singer cycle inGLn(Fq) is shown to be (q n − 1) n−1. Formulas counting factorizations of any length, and counting those with reflections of fixed conjugacy classes are also given. Résumé. Nous prouvons que le nombre de factorisations de longueur minimale d’un cycle de Singer dans GLn(Fq) comme un produit de réflexions est (q n −1) n−1. Nous présentons aussi des formules donnant le nombre de factorisations de toutes les longueurs ainsi que des formules pour le nombre de factorisations comme produit de réflexions ayant des classes de conjugaison fixes
Optical Tweezers as an Effective Tool for Spermatozoa Isolation from Mixed Forensic Samples
A single focus optical tweezer is formed when a laser beam is launched through a high numerical aperture immersion objective. This objective focuses the beam down to a diffraction-limited spot, which creates an optical trap where cells suspended in aqueous solutions can be held fixed. Spermatozoa, an often probative cell type in forensic investigations, can be captured inside this optical trap and dragged one by one across millimeter-length distances in order to create a cluster of cells which can be subsequently drawn up into a capillary for collection. Sperm cells are then ejected onto a sterile cover slip, counted, and transferred to a tube for DNA analysis workflow. The objective of this research was to optimize sperm cell collection for maximum DNA yield, and to determine the number of trapped sperm cells necessary to produce a full STR profile. A varying number of sperm cells from both a single-source semen sample and a mock sexual assault sample were isolated utilizing optical tweezers and processed using conventional STR analysis methods. Results demonstrated that approximately 50 trapped spermatozoa were required to obtain a consistently full DNA profile. A complete, single-source DNA profile was also achieved by isolating sperm cells via optical trapping from a mixture of sperm and vaginal epithelial cells. Based on these results, optical tweezers are a viable option for forensic applications such as separation of mixed populations of cells in forensic evidence
Multigraded Castelnuovo-Mumford Regularity
We develop a multigraded variant of Castelnuovo-Mumford regularity. Motivated
by toric geometry, we work with modules over a polynomial ring graded by a
finitely generated abelian group. As in the standard graded case, our
definition of multigraded regularity involves the vanishing of graded
components of local cohomology. We establish the key properties of regularity:
its connection with the minimal generators of a module and its behavior in
exact sequences. For an ideal sheaf on a simplicial toric variety X, we prove
that its multigraded regularity bounds the equations that cut out the
associated subvariety. We also provide a criterion for testing if an ample line
bundle on X gives a projectively normal embedding.Comment: 30 pages, 5 figure
High transport currents in mechanically reinforced MgB2 wires
We prepared and characterized monofilamentary MgB2 wires with a mechanically
reinforced composite sheath of Ta(Nb)/Cu/steel, which leads to dense filaments
and correspondingly high transport currents up to Jc = 10^5 A/cm^2 at 4.2 K,
self field. The reproducibility of the measured transport currents was
excellent and not depending on the wire diameter. Using different precursors,
commercial reacted powder or an unreacted Mg/B powder mixture, a strong
influence on the pinning behaviour and the irreversibility field was observed.
The critical transport current density showed a nearly linear temperature
dependency for all wires being still 52 kA/cm^2 at 20 K and 23 kA/cm^2 at 30 K.
Detailed data for Jc(B,T) and Tc(B) were measured.Comment: 21 pages, 13 figures, revised version, to be published in Supercond.
Sci. Techno
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Trust in Government and Effective Nuclear Safety Governance in Great Britain
Nuclear power can play a role in reducing CO2 emissions and improving energy security. Public attitudes to nuclear safety governance will be critical in whether a large-scale rollout of nuclear power will be successful, so we commissioned a survey of 1,007 members of the British public to understand the determinants of such views. In particular, we focus on the role of trust in government, which has been largely neglected as a subject of study. We find that higher risk perceptions of new nuclear power technologies is associated with lower overall government trustworthiness, while higher engagement levels, being male and intentions to vote Conservative increase trustworthiness. Risk perceptions towards old and the new nuclear technologies do not differ significantly, which raises questions about the view that newer defence-in-depth nuclear technologies can reduce public fear of nuclear power. To build public trust, the UK government must demonstrate its trustworthiness in nuclear safety governance, especially along the dimensions of integrity, reliability and openness. Further, improving stakeholder engagement and thus increasing the levels of public satisfaction towards the government are necessary. Our novel research methodology of determining government trustworthiness in relation to public risk perceptions, technical knowledge, and stakeholder engagement is more broadly applicable and can be transferred to other subject areas and to countries where public concerns over nuclear safety and energy security are significant
Conditional control of quantum beats in a cavity QED system
We probe a ground-state superposition that produces a quantum beat in the
intensity correlation of a two-mode cavity QED system. We mix drive with
scattered light from an atomic beam traversing the cavity, and effectively
measure the interference between the drive and the light from the atom. When a
photon escapes the cavity, and upon detection, it triggers our feedback which
modulates the drive at the same beat frequency but opposite phase for a given
time window. This results in a partial interruption of the beat oscillation in
the correlation function, that then returns to oscillate.Comment: 9 pages, 5 figures, XVII Reuni\'on Iberoamericana de \'Optica, X
Encuentro de \'Optica, L\'aseres y Aplicaciones (RIAO-OPTILAS-2010
Relativistic Proton Production During the 14 July 2000 Solar Event: The Case for Multiple Source Mechanisms
Protons accelerated to relativistic energies by transient solar and
interplanetary phenomena caused a ground-level cosmic ray enhancement on 14
July 2000, Bastille Day. Near-Earth spacecraft measured the proton flux
directly and ground-based observatories measured the secondary responses to
higher energy protons. We have modelled the arrival of these relativistic
protons at Earth using a technique which deduces the spectrum, arrival
direction and anisotropy of the high-energy protons that produce increased
responses in neutron monitors. To investigate the acceleration processes
involved we have employed theoretical shock and stochastic acceleration
spectral forms in our fits to spacecraft and neutron monitor data. During the
rising phase of the event (10:45 UT and 10:50 UT) we find that the spectrum
between 140 MeV and 4 GeV is best fitted by a shock acceleration spectrum. In
contrast, the spectrum at the peak (10:55 UT and 11:00 UT) and in the declining
phase (11:40 UT) is best fitted with a stochastic acceleration spectrum. We
propose that at least two acceleration processes were responsible for the
production of relativistic protons during the Bastille Day solar event: (1)
protons were accelerated to relativistic energies by a shock, presumably a
coronal mass ejection (CME). (2) protons were also accelerated to relativistic
energies by stochastic processes initiated by magnetohydrodynamic (MHD)
turbulence.Comment: 38 pages, 9 figures, accepted for publication in the Astrophysical
Journal, January, 200
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