An Equilibrium Prediction Method for Control and Fault Detection of Energy Systems

Author(s):  
Austin Rogers ◽  
Fangzhou Guo ◽  
Bryan Rasmussen

Abstract Many fault detection, optimization, and control logic methods rely on sensor feedback that assumes the system is operating at steady state conditions, despite persistent transient disturbances. While filtering and signal processing techniques can eliminate some transient effects, this paper proposes an equilibrium prediction method for first order dynamic systems using an exponential regression. This method is particularly valuable for many commercial and industrial energy system, whose dynamics are dominated by first order thermo-fluid effects. To illustrate the basic advantages of the proposed approach, Monte Carlo simulations are used. This is followed by three distinct experimental case studies to demonstrate the practical efficacy of the proposed method. First, the ability to predict the carbon dioxide level in classrooms allows for energy efficient control of the ventilation system and ensures occupant comfort. Second, predicting the optimal time to end the cool-down of an industrial sintering furnace allows for maximum part throughput and worker safety. Finally, fault detection and diagnosis methods for air conditioning systems typically use static system models; however, the transient response of many air conditioning signals may be approximated as first order, and therefore, the prediction model enables the use of static fault detection methods with transient data. In this paper, the equilibrium prediction method's performance will be quantified using both Monte Carlo simulations and case studies.

2013 ◽  
Vol 13 (03) ◽  
pp. 1250075 ◽  
Author(s):  
VAHID ZEINODDINI MEIMAND ◽  
LORI GRAHAM-BRADY ◽  
BENJAMIN WILLIAM SCHAFER

The objective of this paper is to demonstrate how simple bar-spring models can illustrate elementary and advanced structural behavior, including stability, imperfection sensitivity, and plastic collapse. In addition, the same bar-spring models also provide a ready means for assessing structural reliability. Bar-spring models for a column (both post-buckling stable and unstable), a frame, and a plate are all developed. For each model the influence of geometric imperfections are explicitly introduced and the ultimate strength considering plastic collapse of the supporting springs derived. The developed expressions are compared to material and geometric nonlinear finite element analysis models of analogous continuous systems, using yield surface based plastic hinge beam elements (in MASTAN) for the column and frame and shell elements (in ABAQUS) for the plate. The results show excellent qualitative agreement, and surprisingly good quantitative agreement. The developed bar-spring models are used in Monte Carlo simulations and in the development of first order Taylor Series approximations to provide the statistics of the ultimate strength as used in structural reliability calculations. Good agreement between conventional first order second moment assumptions and the Monte Carlo simulations of the bar-spring models is demonstrated. It is intended that the developed models provide a useful illustration of basic concepts central to structural stability and structural reliability.


2021 ◽  
Author(s):  
Shokofe Rahimi ◽  
Majid Ataee-pour ◽  
Hasan Madani

Abstract It is very difficult to predict the emission of coal gas before the extraction, because it depends on various geological, geographical and operational factors. Gas content is a very important parameter for assessing gas emission in the coal seam during and after the extraction. Large amounts of gas released during the mining cause concern about adequate airflow for the ventilation and worker safety. Hence, the performance of the ventilation system is very important in an underground mine. In this paper, the gas content uncertainty in a coal seam is first investigated using the central data of 64 exploratory boreholes. After identifying the important coal seams in terms of gas emission, the variogram modeling for gas content was performed to define the distribution. Consecutive simulations were run for the random evaluation of gas content. Then, a method was proposed to predict gas emission based on the Monte Carlo random simulation method. In order to improve the reliability and precision of gas emission prediction, various factors affecting the gas emission were investigated and the main factors determining the gas emission were identified based on a sensitivity analysis on the mine data. This method produced relative and average errors of 2% and 0.57%, respectively. The results showed that the proposed model is accurate enough to determine the amount of emitted gas and ventilation. In addition, the predicted value was basically consistent with the actual value and the gas emission prediction method based on the uncertainty theory is reliable.


2012 ◽  
Vol 548 ◽  
pp. 521-526 ◽  
Author(s):  
Xing Hao Wang ◽  
Jiang Shao ◽  
Xiao Yu Liu

Different from the reliability prediction method on handbook, the reliability prediction method based on Physics of Failure (PoF) model takes failure mechanism as theoretical basis, and combines the design in-formation with the environment stress of the product to predict the time to failure. When the uncertain of the parameters is considered to predict the reliability, Monte-Carlo calculation method is always used here. How-ever, the Monte-Carlo method needs large computational cost, especially for large and complicated electronic systems. A new reliability prediction method which combines the first order reliability with the reliability pre-diction method based on PoF model was proposed. The new method utilized the first order method to calculate the position of design point and reliability index, thus Monte-Carlo calculation process was avoided. Example calculation results showed that the new method improves the prediction efficiency without decreasing the accuracy of reliability, thus it is feasible for reliability prediction of electronic product in engineering.


2009 ◽  
Vol 12 (1) ◽  
pp. 96-97 ◽  
Author(s):  
Benjamin P. Geisler ◽  
Uwe Siebert ◽  
G. Scott Gazelle ◽  
David J. Cohen ◽  
Alexander Göhler

1997 ◽  
Vol 493 ◽  
Author(s):  
J. Romero ◽  
L. F. Fonseca

ABSTRACTThe macroscopic polarization of ferroelectric thin films was studied by Monte Carlo simulations using a Transverse Ising Model Hamiltonian with four-spins interactions. The dependence of the ferroelectric phase transition temperature, Tc, on the thickness of the film was obtained resulting in a shifting of Tc towards lower temperatures and a change from first-order to second-order phase transition as the thickness of the film is reduced. Comparison between the surface and internal order was carried out by the calculation of layer-averaged polarizations as a function of the sample temperature and the surface interaction parameters. These comparisons show that increasing disorder at the surface can be reverted by increasing the four-spins surface interactions.


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