19,450 research outputs found
Privacy-Protecting Energy Management Unit through Model-Distribution Predictive Control
The roll-out of smart meters in electricity networks introduces risks for
consumer privacy due to increased measurement frequency and granularity.
Through various Non-Intrusive Load Monitoring techniques, consumer behavior may
be inferred from their metering data. In this paper, we propose an energy
management method that reduces energy cost and protects privacy through the
minimization of information leakage. The method is based on a Model Predictive
Controller that utilizes energy storage and local generation, and that predicts
the effects of its actions on the statistics of the actual energy consumption
of a consumer and that seen by the grid. Computationally, the method requires
solving a Mixed-Integer Quadratic Program of manageable size whenever new meter
readings are available. We simulate the controller on generated residential
load profiles with different privacy costs in a two-tier time-of-use energy
pricing environment. Results show that information leakage is effectively
reduced at the expense of increased energy cost. The results also show that
with the proposed controller the consumer load profile seen by the grid
resembles a mixture between that obtained with Non-Intrusive Load Leveling and
Lazy Stepping.Comment: Accepted for publication in IEEE Transactions on Smart Grid 2017,
special issue on Distributed Control and Efficient Optimization Methods for
Smart Gri
Enhancement of height system for Malaysia using space technology: the study of the datum bias inconsistencies in Peninsular Malaysia
The algorithm for orthometric height transfer using GPS has been widely presented. Its practical limitations are mostly due to datum bias inconsistencies and lack of precise geoid. In most applications, datum biases are assumed to be systematic over short baselines and therefore could be eliminated by differential heighting techniques. In this study, optimal algorithms were investigated to model biases between local vertical datum in Peninsular Malaysia and the datums implied by by EGM96, OSU91A and the regional Gravimetric Geoid in South_East Asia. The study has indicated that local vertical datum is not physically parallel to the datums implied by the above geoids. The shift parameters between the datums implied by the GPS/leveling data, and the EGM96, OSU91A and the gravimetric datums are about – 41cm, -54 cm and – 8 cm respectively. Also the maximum tilts of the planes fitting the residual geoids above these datums relative to GPS/Leveling datum are of the order of 36, 51 and 33 centimeters per degree. It is therefore necessary to take into account the effect of inconsistent datum bias particularly for baseline height transfer. The level of accuracy achieved by the bias corrected relative orthometric height differences of the EGM96, OSU91A and the gravimetric geoid models combined with GPS/leveling data for baseline lengths up to 36 km, is sufficient to replace the conventional tedious, time consuming ordinary leveling technique for rapid height transfer for land surveying and engineering applications
A Numerical Simulation of Chern-Simons Inflation
In this work, we present results of numerical simulations of the Chern-Simons
Inflation Model proposed by Alexander, Marciano and Spergel. According to this
model, inflation begins with a fermion condensate interacting with a gauge
field. Crucial to the success of this mechanism is the assumption that the
Chern-Simons interaction would drive energy from the initial random spectrum
into a narrow band of frequencies at superhorizon scales. In this work we
numerically confirm this expectation. These gauge fields and currents, when
combined with the Friedmann equations, were broken into a system of hyperbolic
equations and numerically simulated. It was found in our simulation that, by
including the effects of the chiral anomaly for the axial vector current,
inflation ended satisfactorily after approximately 60 e-folds.Comment: 6 pages, 8 figure
Regional quasigeoid determination in Northern Germany and comparison with GPS
For the northern part of the Federal Republic of Germany, new quasigeoid solutions were computed by least squares collocation and fast Fourier transformation (FFT) techniques using point and mean gravity data, a digital terrain model, and a global geopotential model. As severe accuracy limitations for precise regional quasigeoid determination come from global model uncertainties, different geopotential models were investigated by combining them with gravimetric data and comparing the quasigeoid heights with GPS and leveling. Optimum results were obtained by a global model tailored to gravity data in Europe. Collocation and FFT results based on this model agree well. The comparison with GPS and leveling yields rms discrepancies of + or - 2 cm over approximately 400 km range
Converting NAD83 GPS heights into NAVD88 elevations with LVGEOID, a hybrid geoid height model for the Long Valley volcanic region, California
A GPS survey of leveling benchmarks done in Long
Valley Caldera in 1999 showed that the application of the
National Geodetic Survey (NGS) geoid model GEOID99 to
tie GPS heights to historical leveling measurements would
significantly underestimate the caldera ground deformation (known from other geodetic measurements). The NGS
geoid model was able to correctly reproduce the shape of the
deformation, but required a local adjustment to give a realistic estimate of the magnitude of the uplift. In summer 2006,
the U.S. Geological Survey conducted a new leveling survey
along two major routes crossing the Long Valley region from
north to south (Hwy 395) and from east to west (Hwy 203 –
Benton Crossing). At the same time, 25 leveling bench marks
were occupied with dual frequency GPS receivers to provide a
measurement of the ellipsoid heights. Using the heights from
these two surveys, we were able to compute a precise geoid
height model (LVGEOID) for the Long Valley volcanic region.
Our results show that although the LVGEOID and the latest
NGS GEOID03 model practically coincide in areas outside
the caldera, there is a difference of up to 0.2 m between the
two models within the caldera. Accounting for this difference
is critical when using the geoid height model to estimate the
ground deformation due to magmatic or tectonic activity in the
calder
Electrochemical energy storage systems for solar thermal applications
Existing and advanced electrochemical storage and inversion/conversion systems that may be used with terrestrial solar-thermal power systems are evaluated. The status, cost and performance of existing storage systems are assessed, and the cost, performance, and availability of advanced systems are projected. A prime consideration is the cost of delivered energy from plants utilizing electrochemical storage. Results indicate that the five most attractive electrochemical storage systems are the: iron-chromium redox (NASA LeRC), zinc-bromine (Exxon), sodium-sulfur (Ford), sodium-sulfur (Dow), and zinc-chlorine (EDA)
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