2,560 research outputs found
Distributional Analysis for Model Predictive Deferrable Load Control
Deferrable load control is essential for handling the uncertainties
associated with the increasing penetration of renewable generation. Model
predictive control has emerged as an effective approach for deferrable load
control, and has received considerable attention. In particular, previous work
has analyzed the average-case performance of model predictive deferrable load
control. However, to this point, distributional analysis of model predictive
deferrable load control has been elusive. In this paper, we prove strong
concentration results on the distribution of the load variance obtained by
model predictive deferrable load control. These concentration results highlight
that the typical performance of model predictive deferrable load control is
tightly concentrated around the average-case performance.Comment: 12 pages, technical report for CDC 201
Approaches to Support Student Learning in Introductory Programming Laboratory Classes
Objectives: This thesis will explore some innovative solutions to communication difficulties that exist in higher education teaching of introductory programming. Communication between a teacher and student is important, as it is the main opportunity where a student can ask a teacher questions about a particular problem they have, and a teacher can give feedback to direct them towards a solution. It is expected that through utilising technology in laboratory practical classes, communication between teachers and student can be improved.
Methods: This thesis primarily explores the possibilities of using student compiler and method invocation data, collected during a practical class and sent directly to a teacher. This data maybe beneficial as a method of allowing teachers to see if a student requires help. This thesis utilises a variety of research methods including questionnaires, observations of classroom interactions and collection of data recorded from student and teachers interactions with the technology. The approaches are used during an investigation into the current approaches of laboratory practical teaching, before progressing onto investigations using the technology developed that accompanies this thesis.
Results: The results identified that the majority of the students and teachers who used the technology felt that it improved their ability to communicate within laboratory practical classes. The teachers felt that they could use the data collected by the technology to view activity from the students and see a student’s progress. The teachers could interpret the data collected from the technology and students who needed help could be identified.
Conclusions: This thesis has demonstrated that technology has the potential to improve communication in laboratory classes, and enable teachers to support students more effectively. However, the technology developed in this thesis, does not eliminate the requirement for a teacher to interact with a student face-to-face, but rather its role is to act as an indicator of students who may need assistance
Less is More: Real-time Failure Localization in Power Systems
Cascading failures in power systems exhibit non-local propagation patterns
which make the analysis and mitigation of failures difficult. In this work, we
propose a distributed control framework inspired by the recently proposed
concepts of unified controller and network tree-partition that offers strong
guarantees in both the mitigation and localization of cascading failures in
power systems. In this framework, the transmission network is partitioned into
several control areas which are connected in a tree structure, and the unified
controller is adopted by generators or controllable loads for fast timescale
disturbance response. After an initial failure, the proposed strategy always
prevents successive failures from happening, and regulates the system to the
desired steady state where the impact of initial failures are localized as much
as possible. For extreme failures that cannot be localized, the proposed
framework has a configurable design, that progressively involves and
coordinates more control areas for failure mitigation and, as a last resort,
imposes minimal load shedding. We compare the proposed control framework with
Automatic Generation Control (AGC) on the IEEE 118-bus test system. Simulation
results show that our novel framework greatly improves the system robustness in
terms of the N-1 security standard, and localizes the impact of initial
failures in majority of the load profiles that are examined. Moreover, the
proposed framework incurs significantly less load loss, if any, compared to
AGC, in all of our case studies
Failure Localization in Power Systems via Tree Partitions
Cascading failures in power systems propagate non-locally, making the control
and mitigation of outages extremely hard. In this work, we use the emerging
concept of the tree partition of transmission networks to provide an analytical
characterization of line failure localizability in transmission systems. Our
results rigorously establish the well perceived intuition in power community
that failures cannot cross bridges, and reveal a finer-grained concept that
encodes more precise information on failure propagations within tree-partition
regions. Specifically, when a non-bridge line is tripped, the impact of this
failure only propagates within well-defined components, which we refer to as
cells, of the tree partition defined by the bridges. In contrast, when a bridge
line is tripped, the impact of this failure propagates globally across the
network, affecting the power flow on all remaining transmission lines. This
characterization suggests that it is possible to improve the system robustness
by temporarily switching off certain transmission lines, so as to create more,
smaller components in the tree partition; thus spatially localizing line
failures and making the grid less vulnerable to large-scale outages. We
illustrate this approach using the IEEE 118-bus test system and demonstrate
that switching off a negligible portion of transmission lines allows the impact
of line failures to be significantly more localized without substantial changes
in line congestion
Extracting |V_{ub}| from the Hadronic Mass Spectrum of Inclusive B decays
Following a strategy introduced earlier by the authors, we show that it is
possible to extract |V_{ub}| from the cut hadronic mass spectrum of B decays
without large systematic errors which usually arise from having to model the
Fermi motion of the heavy quark. We present a closed form expression for
|V_{ub}|/|V_{ts}| which is accurate up to corrections of order \alpha_s^2,
\alpha_s \rho, (\Lambda/m_b)^2/\rho, where \rho is the experimental cut
(s_c/m_b^2) on the hadronic mass used to veto charmed decays. Modulo duality
violation errors, which are intrinsic to all inclusive predictions, we estimate
the theoretical error in the extraction to be at the 5% level.Comment: 11 pages, 1 figur
Real-time Flexibility Feedback for Closed-loop Aggregator and System Operator Coordination
Aggregators have emerged as crucial tools for the coordination of distributed, controllable loads. However, to be used effectively, aggregators must be able to communicate the available flexibility of the loads they control to the system operator in a manner that is both (i) concise enough to be scalable to aggregators governing hundreds or even thousands of loads and (ii) informative enough to allow the system operator to send control signals to the aggregator that lead to optimization of system-level objectives, such as cost minimization, and do not violate private constraints of the loads, such as satisfying specific load demands. In this paper, we present the design of a real-time flexibility feedback signal based on maximization of entropy. The design provides a concise and informative signal that can be used by the system operator to perform online cost minimization and real-time capacity estimation, while provably satisfying the private constraints of the loads. In addition to deriving analytic properties of the design, we illustrate the effectiveness of the design using a dataset from an adaptive electric vehicle charging network
What if the Higgs couplings to W and Z bosons are larger than in the Standard Model?
We derive a general sum rule relating the Higgs coupling to W and Z bosons to
the total cross section of longitudinal gauge boson scattering in I=0,1,2
isospin channels. The Higgs coupling larger than in the Standard Model implies
enhancement of the I=2 cross section. Such an enhancement could arise if the
Higgs sector is extended by an isospin-2 scalar multiplet including a doubly
charged, singly charged, and another neutral Higgs.Comment: 11 pages, no figures. v2: comments and references added. v3: early
QCD references adde
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