Characterization of Damping and Beating Effects Within the Aggregate Power Demand of Heterogeneous Thermostatically Controlled Loads

2015 ◽  
Author(s):  
Donald J. Docimo ◽  
Hosam K. Fathy
Keyword(s):  
Population Heterogeneity ◽  
Parameter Distribution ◽  
Population Parameter ◽  
Control Input ◽  
Power Demand ◽  
Response Dynamics ◽  
Parameter Heterogeneity ◽  
Thermostatically Controlled Loads ◽  
Aggregate Dynamics

This paper presents an analysis of the damping and beating effects within the aggregate power demand of heterogeneous thermostatically controlled loads (TCLs). Demand response using TCLs is an appealing method to enable higher levels of penetration of intermittent renewable resources into the electric grid. Previous literature covers the benefits of TCL population heterogeneity for control purposes, but the focus is solely on the damping observed in these systems. This work is, to the best of the authors’ knowledge, the first to characterize the combined damping and beating response of power demand versus the level of TCL population parameter heterogeneity. The forced aggregate dynamics of TCLs have been shown to be bilinear when set point temperature adjustment is used as a control input. This motivates the paper’s use of free response dynamics, which are linear, to characterize both the damping and beating phenomena. A stochastic parameter distribution is applied to the homogeneous power demand solution, furnishing an analytic expression for aggregate power demand. The resulting analysis shows that increasing parameter heterogeneity increases damping and shortens the beat period.

Demand Response Using Heterogeneous Thermostatically Controlled Loads: Characterization of Aggregate Power Dynamics

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Donald Docimo ◽  
Hosam K. Fathy
Keyword(s):  
Demand Response ◽  
Population Heterogeneity ◽  
Power Dynamics ◽  
Parameter Distribution ◽  
Control Input ◽  
Power Demand ◽  
Response Dynamics ◽  
Parameter Heterogeneity ◽  
Thermostatically Controlled Loads ◽  
Aggregate Dynamics

This article presents an analysis of the damping and beating effects within the aggregate power demand of heterogeneous thermostatically controlled loads (TCLs). Demand response using TCLs is an appealing method to enable higher levels of penetration of intermittent renewable resources into the electric grid. Previous literature covers the benefits of TCL population heterogeneity for control purposes, but the focus is solely on the damping observed in these systems. This work, in contrast, characterizes the combined damping and beating effects in the power demand for different types of TCL parameter heterogeneity. The forced aggregate dynamics of TCLs have been shown to be bilinear when set point temperature adjustment is used as a control input. This motivates the article's use of free response dynamics, which are linear, to characterize both the damping and beating phenomena. A stochastic parameter distribution is applied to the homogeneous power demand solution, furnishing an analytic expression for the aggregate power demand. The time-varying damping ratios of this reduced-order model characterize the damping in the system. By analyzing a variety of case studies, it is determined that only a distribution of the TCL characteristic frequency creates damping in the aggregate power dynamics. The beating effect decays over time due to damping, and a relationship between the beat's amplitude and period is presented.

Design, Modeling, and Experimental Drag Characterization of a Bio-Inspired, Shape-Adapting Underwater Vehicle

2018 ◽  
Author(s):  
Levi D. DeVries ◽  
Michael D. M. Kutzer ◽  
Rebecca E. Richmond ◽  
Archie C. Bass
Keyword(s):  
Spatial Scales ◽  
Autonomous Underwater Vehicles ◽  
Major Axis ◽  
Underwater Vehicle ◽  
Great Promise ◽  
Hydrodynamic Drag ◽  
Control Input ◽  
Semi Major Axis ◽  
Generative Modeling

Autonomous underwater vehicles (AUVs) have shown great promise in fulfilling surveillance, scavenging, and monitoring tasks, but can be hindered in expansive, cluttered or obstacle ridden environments. Traditional gliders and streamlined AUVs are designed for long term operational efficiency in expansive environments, but are hindered in cluttered spaces due to their shape and control authority; agile AUVs can penetrate cluttered or sensitive environments but are limited in operational endurance at large spatial scales. This paper presents the prototype testbed design, modeling, and experimental hydrodynamic drag characterization of a novel self-propelled underwater vehicle capable of actuating its shape morphology. The vehicle prototype incorporates flexible, buckled fiberglass ribs to ensure a rigid shape that can be actuated by modulating the length of the semi-major axis. Tools from generative modeling are used to represent the vehicle shape by using a single control input actuating the vehicles length-to-diameter ratio. By actuating the length and width characteristics of the vehicle’s shape to produce a desired drag profile, we derive the feasible speeds achievable by shape actuation control. Tow-tank experiments with an experimental proto-type suggest shape actuation can be used to manipulate the drag by a factor between 2.15 and 5.8 depending on the vehicle’s operating speed.

scholarly journals Maximum Entropy Framework For Inference Of Cell Population Heterogeneity In Signaling Networks

2017 ◽  
Author(s):  
Purushottam D. Dixit ◽  
Eugenia Lyashenko ◽  
Mario Niepel ◽  
Dennis Vitkup
Keyword(s):  
Cell Population ◽  
Egf Receptor ◽  
Joint Probability ◽  
Network Models ◽  
Population Heterogeneity ◽  
Signaling Networks ◽  
Joint Probability Distribution ◽  
Parameter Distribution ◽  
Signaling Dynamics ◽  
Phosphorylated Akt

AbstractPredictive models of signaling networks are essential tools for understanding cell population heterogeneity and designing rational interventions in disease. However, using network models to predict signaling dynamics heterogeneity is often challenging due to the extensive variability of signaling parameters across cell populations. Here, we describe a Maximum Entropy-based fRamework for Inference of heterogeneity in Dynamics of sIgAling Networks (MERIDIAN). MERIDIAN allows us to estimate the joint probability distribution over signaling parameters that is consistent with experimentally observed cell-to-cell variability in abundances of network species. We apply the developed approach to investigate the heterogeneity in the signaling network activated by the epidermal growth factor (EGF) and leading to phosphorylation of protein kinase B (Akt). Using the inferred parameter distribution, we also predict heterogeneity of phosphorylated Akt levels and the distribution of EGF receptor abundance hours after EGF stimulation. We discuss how MERIDIAN can be generalized and applied to problems beyond modeling of heterogeneous signaling dynamics.

EXPLORING THE EFFECTS OF PARAMETER HETEROGENEITY ON THE INTRINSIC DYNAMICS OF HIV/AIDS IN HETEROSEXUAL SETTINGS

2011 ◽  
Vol 04 (01) ◽  
pp. 75-92
Author(s):  
E. T. NGARAKANA-GWASIRA ◽  
C. P. BHUNU ◽  
S. MUSHAYABASA ◽  
S. D. HOVE-MUSEKWA ◽  
W. GARIRA ◽  
...  
Keyword(s):  
Population Heterogeneity ◽  
Transmission Dynamics ◽  
Heterosexual Transmission ◽  
Related Parameter ◽  
Basic Model ◽  
Progression Model ◽  
Mathematical Properties ◽  
Parameter Heterogeneity ◽  
Epidemiological Parameters ◽  
Hiv Aids

A sex-structured staged progression model for heterosexual transmission dynamics of HIV/AIDS in a community to theoretically assess the effects of gender parameter accounting for population heterogeneity is formulated and analyzed. The basic model without this parameter is analyzed, and then extended to include gender heterogeneity in order to explore its role on the transmission dynamics of the disease. Mathematical properties including epidemic thresholds known as reproductive numbers are derived. The models are numerically analysed using some demographic and epidemiological parameters for Zimbabwe. These simulations suggest that the use of identical gender attributes simplifies computation at the expense of reality as it underestimates the size of the epidemic by 5%. This study demonstrates that the use of gender related parameter in the transmission dynamics of HIV gives a better estimate of the prevalence of the epidemic and should be given prominence.

A Basic Study on the Response Dynamics of Pulse-Frequency Controlled Digital Hydraulic Drives

2013 ◽  
Author(s):  
Christoph Gradl ◽  
Rudolf Scheidl
Keyword(s):  
Pulse Width ◽  
Pulse Width Modulation ◽  
Control Strategies ◽  
Frequency Control ◽  
Hydraulic Drive ◽  
Pulse Frequency ◽  
Control Input ◽  
Response Dynamics ◽  
Basic Study ◽  
Performance Requirements

Various control strategies in digital hydraulics have been proposed and studied so far. In hydraulic switching control Pulse Width Modulation (PWM) of one or two switching valves was mostly considered. This paper deals with Pulse Frequency Control (PFC) which — opposite to PWM — uses the pulse repeating frequency and not the pulse width as control input. PFC may be to be preferred if the hydraulic switching device can realize a very particular pulse in a quite favorable way. This paper studies the influences of the flow rate pulse shapes and of the pulse frequency on the overall system dynamics. Based on a dimensionless mathematical model of a simple linear hydraulic drive and on elementary performance requirements (e.g. overshooting and pressure pulsations) dimensioning rules are derived. In addition to a repeated pulsing single or just a few pulses are investigated. It turns out that particular single or twin pulses can realize stepping motions of the drive without subsequent pulsations. In this way a hydraulic stepping drive can be realized. In case of repeated pulsing, high pulsing frequencies, in particular frequencies well above the natural frequency of the drive system, reduce oscillations considerably. Such frequencies may be realized either by one high frequency pulse device or by several pulse devices which are arranged in parallel and are operated in a phase shifted mode.

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