673,433 research outputs found
Authorization Framework for the Internet-of-Things
This paper describes a framework that allows fine-grained
and flexible access control to connected devices with very
limited processing power and memory.
We propose a set of security and performance requirements
for this setting and derive an authorization framework distributing
processing costs between constrained devices and less constrained back-end servers while keeping message exchanges
with the constrained devices at a minimum.
As a proof of concept we present performance results from
a prototype implementing the device part of the framework
Modeling and supervisory control design for a combined cycle power plant
The traditional control strategy based on PID controllers may be unsatisfactory when dealing with processes with large time delay and constraints. This paper presents a supervisory model based constrained predictive controller (MPC) for a combined cycle power plant (CCPP). First, a non-linear dynamic model of CCPP using the laws of physics was proposed. Then, the supervisory control using the linear constrained MPC method was designed to tune the performance of the PID controllers by including output constraints and manipulating the set points. This scheme showed excellent tracking and disturbance rejection results and improved performance compared with a stand-alone PID controller’s scheme
A Non-Cooperative Power Control Game in Delay-Constrained Multiple-Access Networks
A game-theoretic approach for studying power control in multiple-access
networks with transmission delay constraints is proposed. A non-cooperative
power control game is considered in which each user seeks to choose a transmit
power that maximizes its own utility while satisfying the user's delay
requirements. The utility function measures the number of reliable bits
transmitted per joule of energy and the user's delay constraint is modeled as
an upper bound on the delay outage probability. The Nash equilibrium for the
proposed game is derived, and its existence and uniqueness are proved. Using a
large-system analysis, explicit expressions for the utilities achieved at
equilibrium are obtained for the matched filter, decorrelating and minimum mean
square error multiuser detectors. The effects of delay constraints on the
users' utilities (in bits/Joule) and network capacity (i.e., the maximum number
of users that can be supported) are quantified.Comment: To apprear in the proceedings of the 2005 IEEE International
Symposium on Information Theory, Adelaide, Australia, September 4-9, 200
LQG Control and Sensing Co-Design
We investigate a Linear-Quadratic-Gaussian (LQG) control and sensing
co-design problem, where one jointly designs sensing and control policies. We
focus on the realistic case where the sensing design is selected among a finite
set of available sensors, where each sensor is associated with a different cost
(e.g., power consumption). We consider two dual problem instances:
sensing-constrained LQG control, where one maximizes control performance
subject to a sensor cost budget, and minimum-sensing LQG control, where one
minimizes sensor cost subject to performance constraints. We prove no
polynomial time algorithm guarantees across all problem instances a constant
approximation factor from the optimal. Nonetheless, we present the first
polynomial time algorithms with per-instance suboptimality guarantees. To this
end, we leverage a separation principle, that partially decouples the design of
sensing and control. Then, we frame LQG co-design as the optimization of
approximately supermodular set functions; we develop novel algorithms to solve
the problems; and we prove original results on the performance of the
algorithms, and establish connections between their suboptimality and
control-theoretic quantities. We conclude the paper by discussing two
applications, namely, sensing-constrained formation control and
resource-constrained robot navigation.Comment: Accepted to IEEE TAC. Includes contributions to submodular function
optimization literature, and extends conference paper arXiv:1709.0882
Power-Constrained Fuzzy Logic Control of Video Streaming over a Wireless Interconnect
Wireless communication of video, with Bluetooth as an example, represents a compromise between channel conditions, display and decode deadlines, and energy constraints. This paper proposes fuzzy logic control (FLC) of automatic repeat request (ARQ) as a way of reconciling these factors, with a 40% saving in power in the worst channel conditions from economizing on transmissions when channel errors occur. Whatever the channel conditions are, FLC is shown to outperform the default Bluetooth scheme and an alternative Bluetooth-adaptive ARQ scheme in terms of reduced packet loss and delay, as well as improved video quality
Chance-Constrained ADMM Approach for Decentralized Control of Distributed Energy Resources
Distribution systems are undergoing a dramatic transition from a passive
circuit that routinely disseminates electric power among downstream nodes to
the system with distributed energy resources. The distributed energy resources
come in a variety of technologies and typically include photovoltaic (PV)
arrays, thermostatically controlled loads, energy storage units. Often these
resources are interfaced with the system via inverters that can adjust active
and reactive power injections, thus supporting the operational performance of
the system. This paper designs a control policy for such inverters using the
local power flow measurements. The control actuates active and reactive power
injections of the inverter-based distributed energy resources. This strategy is
then incorporated into a chance-constrained, decentralized optimal power flow
formulation to maintain voltage levels and power flows within their limits and
to mitigate the volatility of (PV) resources
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