28,261 research outputs found
Challenges of Primary Frequency Control and Benefits of Primary Frequency Response Support from Electric Vehicles
As the integration of wind generation displaces conventional plants, system inertia provided by rotating mass declines, causing concerns over system frequency stability. This paper implements an advanced stochastic scheduling model with inertia-dependent fast frequency response requirements to investigate the challenges on the primary frequency control in the future Great Britain electricity system. The results suggest that the required volume and the associated cost of primary frequency response increase significantly along with the increased capacity of wind plants. Alternative measures (e.g. electric vehicles) have been proposed to alleviate these concerns. Therefore, this paper also analyses the benefits of primary frequency response support from electric vehicles in reducing system operation cost, wind curtailment and carbon emissions
Wearable Sensor Data Based Human Activity Recognition using Machine Learning: A new approach
Recent years have witnessed the rapid development of human activity
recognition (HAR) based on wearable sensor data. One can find many practical
applications in this area, especially in the field of health care. Many machine
learning algorithms such as Decision Trees, Support Vector Machine, Naive
Bayes, K-Nearest Neighbor, and Multilayer Perceptron are successfully used in
HAR. Although these methods are fast and easy for implementation, they still
have some limitations due to poor performance in a number of situations. In
this paper, we propose a novel method based on the ensemble learning to boost
the performance of these machine learning methods for HAR
Microwave-induced nonequilibrium temperature in a suspended carbon nanotube
Antenna-coupled suspended single carbon nanotubes exposed to 108 GHz
microwave radiation are shown to be selectively heated with respect to their
metal contacts. This leads to an increase in the conductance as well as to the
development of a power-dependent DC voltage. The increased conductance stems
from the temperature dependence of tunneling into a one-dimensional electron
system. The DC voltage is interpreted as a thermovoltage, due to the increased
temperature of the electron liquid compared to the equilibrium temperature in
the leads
Coherent control at its most fundamental: CEP-dependent electron localization in photodissoziation of a H2+ molecular ion beam target
Measurements and calculations of the absolute carrier-envelope phase (CEP)
effects in the photodissociation of the simplest molecule, H2+, with a 4.5-fs
Ti:Sapphire laser pulse at intensities up to (4 +- 2)x10^14 Watt/cm^2 are
presented. Localization of the electron with respect to the two nuclei (during
the dissociation process) is controlled via the CEP of the ultra-short laser
pulses. In contrast to previous CEP-dependent experiments with neutral
molecules, the dissociation of the molecular ions is not preceded by a
photoionization process, which strongly influences the CEP dependence.
Kinematically complete data is obtained by time- and position-resolved
coincidence detection. The phase dependence is determined by a single-shot
phase measurement correlated to the detection of the dissoziation fragments.
The experimental results show quantitative agreement with ab inito 3D-TDSE
calculations that include nuclear vibration and rotation.Comment: new version includes minore changes and adding the supp_material.pd
q-Analogue of Shock Soliton Solution
By using Jackson's q-exponential function we introduce the generating
function, the recursive formulas and the second order q-differential equation
for the q-Hermite polynomials. This allows us to solve the q-heat equation in
terms of q-Kampe de Feriet polynomials with arbitrary N moving zeroes, and to
find operator solution for the Initial Value Problem for the q-heat equation.
By the q-analog of the Cole-Hopf transformation we construct the q-Burgers type
nonlinear heat equation with quadratic dispersion and the cubic nonlinearity.
In q -> 1 limit it reduces to the standard Burgers equation. Exact solutions
for the q-Burgers equation in the form of moving poles, singular and regular
q-shock soliton solutions are found.Comment: 13 pages, 5 figure
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Comparing carbon sequestration in an oil reservoir to sequestration in a brine formation-field study
Geologic sequestration of CO2 in an oil reservoir is generally considered a different class than sequestration in
formations which contain only brine. In this paper, the significance and validity of this conceptualization is
examined by comparing the performance of CO2 injected into a depleted oil reservoir with the performance of
similar injection into non-oil bearing sandstones using a field test at Cranfield Field, Mississippi as a case study. The
differences considered are:
(1)Residual oil in the reservoir slightly reduces the CO2 breakthrough time and rate of pressure build up as
compared to a reservoir containing only brine, because under miscible conditions, more CO2 dissolves into oil
than in to brine.
(2)Dense wells provide improved assessment of the oil reservoir quality leading to improved prediction as well as
verification of CO2 movement in this reservoir as compared to the sparsely characterized brine leg. The value of
this information exceeds the risk of leakage.
Assessment of the difference made by the presence of residual oil requires a good understanding reservoir properties
to predict oil and gas distribution. Stratal slicing, attribute analysis and petrographic analyses are used to define the
reservoir architecture. Real-time pressure response at a dedicated observation well and episodic pressure mapping
has been conducted in the reservoir under flood since mid-2008; comparison measurements are planned for 2009 in
down-dip environments lacking hydrocarbons. Model results using GEM compositional simulator compare well in
general to measured reservoir response under CO2 flood; imperfections in model match of flood history document
uncertainties Time laps RST logging is underway to validate fluid composition and migration models. Monitoring
assessing the performance of the wells during the injection of CO2 suggests that the value of wells to provide field
data for characterization exceeds the risk of leakage.Bureau of Economic Geolog
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