799 research outputs found
Lessons learned from the Pefki solar village in Athens, nearly 20 years on
Solar Village 3 in Pefki, Athens, was part of an ambitious program, with active and passive solar systems providing space and water heating for 1750 inhabitants, designed in the early 80's, and inhabited from the late 80's. This paper focuses on passive solar systems applied to a number of the buildings. A survey highlighted the cases of trombe water benches and conservatories as the most frequently, poorly operated systems. Over time this led to a lack of belief by the occupants in the passive systems. Building simulation indicated a much higher cooling load than originally designed for, combined with recent warmer summers and poor maintenance and operation, have led to the present case that many homes have installed air conditioning. Plans for district heating will improve heating provision for residents and reduce CO2 emissions but a lack of a maintenance strategy for the passive systems will surely lead to their increased neglect
Smart Grid Communications: Overview of Research Challenges, Solutions, and Standardization Activities
Optimization of energy consumption in future intelligent energy networks (or
Smart Grids) will be based on grid-integrated near-real-time communications
between various grid elements in generation, transmission, distribution and
loads. This paper discusses some of the challenges and opportunities of
communications research in the areas of smart grid and smart metering. In
particular, we focus on some of the key communications challenges for realizing
interoperable and future-proof smart grid/metering networks, smart grid
security and privacy, and how some of the existing networking technologies can
be applied to energy management. Finally, we also discuss the coordinated
standardization efforts in Europe to harmonize communications standards and
protocols.Comment: To be published in IEEE Communications Surveys and Tutorial
Smart Meter Privacy with an Energy Harvesting Device and Instantaneous Power Constraints
A smart meter (SM) periodically measures end-user electricity consumption and
reports it to a utility provider (UP). Despite the advantages of SMs, their use
leads to serious concerns about consumer privacy. In this paper, SM privacy is
studied by considering the presence of an energy harvesting device (EHD) as a
means of masking the user's input load. The user can satisfy part or all of
his/her energy needs from the EHD, and hence, less information can be leaked to
the UP via the SM. The EHD is typically equipped with a rechargeable energy
storage device, i.e., a battery, whose instantaneous energy content limits the
user's capability in covering his/her energy usage. Privacy is measured by the
information leaked about the user's real energy consumption when the UP
observes the energy requested from the grid, which the SM reads and reports to
the UP. The minimum information leakage rate is characterized as a computable
information theoretic single-letter expression when the EHD battery capacity is
either infinite or zero. Numerical results are presented for a discrete binary
input load to illustrate the potential privacy gains from the existence of a
storage device.Comment: To be published in IEEE ICC201
Smart Meter Privacy: A Utility-Privacy Framework
End-user privacy in smart meter measurements is a well-known challenge in the
smart grid. The solutions offered thus far have been tied to specific
technologies such as batteries or assumptions on data usage. Existing solutions
have also not quantified the loss of benefit (utility) that results from any
such privacy-preserving approach. Using tools from information theory, a new
framework is presented that abstracts both the privacy and the utility
requirements of smart meter data. This leads to a novel privacy-utility
tradeoff problem with minimal assumptions that is tractable. Specifically for a
stationary Gaussian Markov model of the electricity load, it is shown that the
optimal utility-and-privacy preserving solution requires filtering out
frequency components that are low in power, and this approach appears to
encompass most of the proposed privacy approaches.Comment: Accepted for publication and presentation at the IEEE SmartGridComm.
201
Smart Meter Privacy with Renewable Energy and a Finite Capacity Battery
We address the smart meter (SM) privacy problem by considering the
availability of a renewable energy source (RES) and a battery which can be
exploited by a consumer to partially hide the consumption pattern from the
utility provider (UP). Privacy is measured by the mutual information rate
between the consumer's energy consumption and the renewable energy generation
process, and the energy received from the grid, where the latter is known by
the UP through the SM readings, and the former two are to be kept private. By
expressing the information leakage as an additive quantity, we cast the problem
as a stochastic control problem, and formulate the corresponding Bellman
equations.Comment: To appear in IEEE SPAWC 201
Robust and Adaptive Functional Logistic Regression
We introduce and study a family of robust estimators for the functional
logistic regression model whose robustness automatically adapts to the data
thereby leading to estimators with high efficiency in clean data and a high
degree of resistance towards atypical observations. The estimators are based on
the concept of density power divergence between densities and may be formed
with any combination of lower rank approximations and penalties, as the need
arises. For these estimators we prove uniform convergence and high rates of
convergence with respect to the commonly used prediction error under fairly
general assumptions. The highly competitive practical performance of our
proposal is illustrated on a simulation study and a real data example which
includes atypical observations
Load Hiding of Household's Power Demand
With the development and introduction of smart metering, the energy
information for costumers will change from infrequent manual meter readings to
fine-grained energy consumption data. On the one hand these fine-grained
measurements will lead to an improvement in costumers' energy habits, but on
the other hand the fined-grained data produces information about a household
and also households' inhabitants, which are the basis for many future privacy
issues. To ensure household privacy and smart meter information owned by the
household inhabitants, load hiding techniques were introduced to obfuscate the
load demand visible at the household energy meter. In this work, a
state-of-the-art battery-based load hiding (BLH) technique, which uses a
controllable battery to disguise the power consumption and a novel load hiding
technique called load-based load hiding (LLH) are presented. An LLH system uses
an controllable household appliance to obfuscate the household's power demand.
We evaluate and compare both load hiding techniques on real household data and
show that both techniques can strengthen household privacy but only LLH can
increase appliance level privacy
A Lightweight Privacy-Preserved Spatial and Temporal Aggregation of Energy Data
Smart grid provides fine-grained real time energy consumption, and it is able to improve the efficiency of energy management. It enables the collection of energy consumption data from consumer and hence has raised serious privacy concerns. Energy consumption data, a form of personal information that reveals behavioral patterns can be used to identify electrical appliances being used by the user through the electricity load signature, thus making it possible to further reveal the residency pattern of a consumer’s household or appliances usage habit. This paper proposes to enhance the privacy of energy con- sumption data by enabling the utility to retrieve the aggregated spatial and temporal consumption without revealing individual energy consumption. We use a lightweight cryptographic mech- anism to mask the energy consumption data by adding random noises to each energy reading and use Paillier’s additive homo- morphic encryption to protect the noises. When summing up the masked energy consumption data for both Spatial and Temporal aggregation, the noises cancel out each other, hence resulting in either the total sum of energy consumed in a neighbourhood at a particular time, or the total sum of energy consumed by a household in a day. No third party is able to derive the energy consumption pattern of a household in real time. A proof-of- concept was implemented to demonstrate the feasibility of the system, and the results show that the system can be efficiently deployed on a low-cost computing platform
Concentrations and fluxes of isoprene and oxygenated VOCs at a French Mediterranean oak forest
The CANOPEE project aims to better understand the biosphere–atmosphere exchanges of biogenic volatile organic compounds (BVOCs) in the case of Mediterranean ecosystems and the impact of in-canopy processes on the atmospheric chemical composition above the canopy. Based on an intensive field campaign, the objective of our work was to determine the chemical composition of the air inside a canopy as well as the net fluxes of reactive species between the canopy and the boundary layer. Measurements were carried out during spring 2012 at the field site of the Oak Observatory of the Observatoire de Haute Provence (O3HP) located in the southeast of France. The site is a forest ecosystem dominated by downy oak, Quercus pubescens Willd., a typical Mediterranean species which features large isoprene emission rates. Mixing ratios of isoprene, its degradation products methylvinylketone (MVK) and methacrolein (MACR) and several other oxygenated VOC (OxVOC) were measured above the canopy using an online proton transfer reaction mass spectrometer (PTR-MS), and fluxes were calculated by the disjunct eddy covariance approach. The O3HP site was found to be a very significant source of isoprene emissions, with daily maximum ambient concentrations ranging between 2–16 ppbv inside and 2–5 ppbv just above the top of the forest canopy. Significant isoprene fluxes were observed only during daytime, following diurnal cycles with midday net emission fluxes from the canopy ranging between 2.0 and 9.7 mg m−2 h1. Net isoprene normalized flux (at 30 °C, 1000 μmol quanta m−2 s−1) was estimated at 7.4 mg m−2 h−1. Evidence of direct emission of methanol was also found exhibiting maximum daytime fluxes ranging between 0.2 and 0.6 mg m−2 h−1, whereas flux values for monoterpenes and others OxVOC such as acetone and acetaldehyde were below the detection limit.
The MVK+MACR-to-isoprene ratio provided useful information on the oxidation of isoprene, and is in agreement with recent findings proposing weak production yields of MVK and MACR, in remote forest regions where the NOx concentrations are low. In-canopy chemical oxidation of isoprene was found to be weak and did not seem to have a significant impact on isoprene concentrations and fluxes above the canopy
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