370 research outputs found
Mobile Conductance in Sparse Networks and Mobility-Connectivity Tradeoff
In this paper, our recently proposed mobile-conductance based analytical
framework is extended to the sparse settings, thus offering a unified tool for
analyzing information spreading in mobile networks. A penalty factor is
identified for information spreading in sparse networks as compared to the
connected scenario, which is then intuitively interpreted and verified by
simulations. With the analytical results obtained, the mobility-connectivity
tradeoff is quantitatively analyzed to determine how much mobility may be
exploited to make up for network connectivity deficiency.Comment: Accepted to ISIT 201
Managing Complex Social Housing Urban Redevelopment Projects through Improved Project Management and Value Generation
Book of abstracts of the workshop:Managing Complex Social Housing Urban Redevelopment Projects through Improved Project Management and Value Generatio
A Contextual Bandit Approach for Value-oriented Prediction Interval Forecasting
Prediction interval (PI) is an effective tool to quantify uncertainty and
usually serves as an input to downstream robust optimization. Traditional
approaches focus on improving the quality of PI in the view of statistical
scores and assume the improvement in quality will lead to a higher value in the
power systems operation. However, such an assumption cannot always hold in
practice. In this paper, we propose a value-oriented PI forecasting approach,
which aims at reducing operational costs in downstream operations. For that, it
is required to issue PIs with the guidance of operational costs in robust
optimization, which is addressed within the contextual bandit framework here.
Concretely, the agent is used to select the optimal quantile proportion, while
the environment reveals the costs in operations as rewards to the agent. As
such, the agent can learn the policy of quantile proportion selection for
minimizing the operational cost. The numerical study regarding a two-timescale
operation of a virtual power plant verifies the superiority of the proposed
approach in terms of operational value. And it is especially evident in the
context of extensive penetration of wind power.Comment: submitted to IEEE Transactions on Smart Gri
Optimal Vehicle Charging in Bilevel Power-Traffic Networks via Charging Demand Function
Electric vehicle (EV) charging couples the operation of power and traffic
networks. Specifically, the power network determines the charging price at
various locations, while EVs on the traffic network optimize the charging power
given the price, acting as price-takers. We model such decision-making
processes by a bilevel program, with the power network at the upper-level and
the traffic network at the lower-level. However, since the two networks are
managed by separate entities and the charging expense term, calculated as the
product of charging price and charging demand, is nonlinear. Solving the
bilevel program is nontrivial. To overcome these challenges, we derive the
charging demand function using multiparametric programming theory. This
function establishes a piecewise linear relationship between the charging price
and the optimal charging power, enabling the power network operator to manage
EV charging power independently while accounting for the coupling between the
two networks. With the derived function, we are also able to replace the
nonlinear charging expense term with a piecewise quadratic one, thus
guaranteeing solution optimality. Our numerical studies demonstrate that
different traffic demands can have an impact on charging patterns and the power
network can effectively incentivize charging at low-price nodes through price
setting.Comment: submitted to IEEE Transactions on Smart Gri
Value-oriented Renewable Energy Forecasting for Coordinated Energy Dispatch Problems at Two Stages
Energy forecasting is deemed an essential task in power system operations.
Operators usually issue forecasts and leverage them to schedule energy dispatch
ahead of time (referred to as the 'predict, then optimize' paradigm). However,
forecast models are often developed via optimizing statistical scores while
overlooking the value of the forecasts in operation. In this paper, we design a
value-oriented point forecasting approach for energy dispatch problems with
renewable energy sources (RESs). At the training phase, this approach
incorporates forecasting with day-ahead/real-time operations for power systems,
thereby achieving reduced operation costs of the two stages. To this end, we
formulate the forecast model parameter estimation as a bilevel program at the
training phase, where the lower level solves the day-ahead and real-time energy
dispatch problems, with the forecasts as parameters; the optimal solutions of
the lower level are then returned to the upper level, which optimizes the model
parameters given the contextual information and minimizes the expected
operation cost of the two stages. Under mild assumptions, we propose a novel
iterative solution strategy for this bilevel program. Under such an iterative
scheme, we show that the upper level objective is locally linear regarding the
forecast model output, and can act as the loss function. Numerical experiments
demonstrate that, compared to commonly used point forecasting methods, the
forecasts obtained by the proposed approach result in lower operation costs in
the subsequent energy dispatch problems. Meanwhile, the proposed approach is
more computationally efficient than traditional two-stage stochastic program.Comment: submitted to European Journal of Operational Researc
3D Automatic Segmentation Method for Retinal Optical Coherence Tomography Volume Data Using Boundary Surface Enhancement
With the introduction of spectral-domain optical coherence tomography
(SDOCT), much larger image datasets are routinely acquired compared to what was
possible using the previous generation of time-domain OCT. Thus, there is a
critical need for the development of 3D segmentation methods for processing
these data. We present here a novel 3D automatic segmentation method for
retinal OCT volume data. Briefly, to segment a boundary surface, two OCT volume
datasets are obtained by using a 3D smoothing filter and a 3D differential
filter. Their linear combination is then calculated to generate new volume data
with an enhanced boundary surface, where pixel intensity, boundary position
information, and intensity changes on both sides of the boundary surface are
used simultaneously. Next, preliminary discrete boundary points are detected
from the A-Scans of the volume data. Finally, surface smoothness constraints
and a dynamic threshold are applied to obtain a smoothed boundary surface by
correcting a small number of error points. Our method can extract retinal layer
boundary surfaces sequentially with a decreasing search region of volume data.
We performed automatic segmentation on eight human OCT volume datasets acquired
from a commercial Spectralis OCT system, where each volume of data consisted of
97 OCT images with a resolution of 496 512; experimental results show that this
method can accurately segment seven layer boundary surfaces in normal as well
as some abnormal eyes.Comment: 27 pages, 19 figure
How evidence-based design supports better value generation for end-users
Interest in Evidence based design (EBD) has been growing extensively. Proper design decisions can not only maximise the occupant's health benefits, but also improve service delivery. There is a clear link between the concept of EBD and that of value generation to guide decision making for better healthcare design. Through an expensive literature review, a conceptual framework is presented, illustrating important decision making steps, considering EBD as means, with an emphasis on how it helps increase the end-users value generation. The paper concludes by identifying limitations and potential future studies
A field survey on the indoor environmental quality of the UK primary school classroom
The indoor environmental quality (thermal, visual, acoustic and air quality) of the primary school classroom has an impact on pupils' learning and wellbeing. A field study, conducted on random days from 2012 to 2013, was carried out in 203 classrooms from 30 primary schools in 3 areas within the UK.
Physical parameters were measured at the site: illuminance, air temperature, relative humidity, CO2 concentration and noise level. It was inferred that: 30.9% classrooms did not meet the proposed standards limiting the level of CO2 levels; light levels were found to be notably low (less than 500lux) because the pedagogy was reliant on smart boards; high noise levels (between 40 to 80dBA) were caused mainly from the adjacent activity areas to the classroom. Based on the findings, practical suggestions are proposed to maximise the environmental benefit to the pupil
Blockchain Network Analysis: A Comparative Study of Decentralized Banks
Decentralized finance (DeFi) is known for its unique mechanism design, which
applies smart contracts to facilitate peer-to-peer transactions. The
decentralized bank is a typical DeFi application. Ideally, a decentralized bank
should be decentralized in the transaction. However, many recent studies have
found that decentralized banks have not achieved a significant degree of
decentralization. This research conducts a comparative study among mainstream
decentralized banks. We apply core-periphery network features analysis using
the transaction data from four decentralized banks, Liquity, Aave, MakerDao,
and Compound. We extract six features and compare the banks' levels of
decentralization cross-sectionally. According to the analysis results, we find
that: 1) MakerDao and Compound are more decentralized in the transactions than
Aave and Liquity. 2) Although decentralized banking transactions are supposed
to be decentralized, the data show that four banks have primary external
transaction core addresses such as Huobi, Coinbase, Binance, etc. We also
discuss four design features that might affect network decentralization. Our
research contributes to the literature at the interface of decentralized
finance, financial technology (Fintech), and social network analysis and
inspires future protocol designs to live up to the promise of decentralized
finance for a truly peer-to-peer transaction network
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