Incorporating Process Architecture in the Evaluation of Stability in Distributed Design

2011 ◽  
Author(s):  
Erich Devendorf ◽  
Kemper Lewis
Keyword(s):  
Solution Process ◽  
System Stability ◽  
System Level ◽  
Design System ◽  
Distributed Design ◽  
Equilibrium Solutions ◽  
General Process ◽  
Architecture Model ◽  
The Stability ◽  
Process Architecture

In distributed design processes, individual design subsystems have local control over design variables and seek to satisfy their own individual objectives, which may also be influenced by some system level objectives. The resulting network of coupled subsystems will either converge to a stable equilibrium, or diverge in an unstable manner. In this paper, we study the dependence of system stability on the solution process architecture. The solution process architecture describes how the design subsystems are ordered and can be either sequential, parallel, or a hybrid that incorporates both parallel and sequential elements. In this paper we demonstrate that the stability of a distributed design system does indeed depend on the solution process architecture chosen and we create a general process architecture model based on linear systems theory. The model allows the stability of equilibrium solutions to be analyzed for distributed design systems by converting any process architecture into an equivalent parallel representation. Moreover, we show that this approach can accurately predict when the equilibrium is unstable and the system divergent when previous models suggest the system is convergent.

The Impact of Process Architecture on Equilibrium Stability in Distributed Design

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Erich Devendorf ◽  
Kemper Lewis
Keyword(s):  
Solution Process ◽  
System Stability ◽  
System Level ◽  
Design System ◽  
Distributed Design ◽  
General Process ◽  
Architecture Model ◽  
The Stability ◽  
Process Architecture ◽  
The Impact

In distributed design processes, individual design subsystems have local control over design variables and seek to satisfy their own individual objectives, which may also be influenced by some system level objectives. The resulting network of coupled subsystems will either converge to a stable equilibrium or diverge in an unstable manner. In this paper, we study the dependence of system stability on the solution process architecture. The solution process architecture describes how the design subsystems are ordered and can be either sequential, parallel, or a hybrid that incorporates both parallel and sequential elements. In this paper, we demonstrate that the stability of a distributed design system does indeed depend on the solution process architecture chosen, and we create a general process architecture model based on linear systems theory. The model allows the stability of equilibrium solutions to be analyzed for distributed design systems by converting any process architecture into an equivalent parallel representation. Moreover, we show that this approach can accurately predict when the equilibrium is unstable and the system divergent when previous models suggest that the system is convergent.

scholarly journals From foodwebs to gene regulatory networks (GRNs) - weak repressions by microRNAs confer system stability

2017 ◽  
Author(s):  
Yuxin Chen ◽  
Yang Shen ◽  
Stefano Allesina ◽  
Chung-I Wu
Keyword(s):  
Regulatory Networks ◽  
Stability Control ◽  
System Stability ◽  
Yeast Cells ◽  
System Level ◽  
Main Function ◽  
Highly Expressed Genes ◽  
Gene Regulatory ◽  
Mechanistic Basis ◽  
The Stability

AbstractMore than 30% of mRNAs are repressed by microRNAs (miRNAs) but most repressions are too weak to have a phenotypic consequence. The diffuse actions have been a central conundrum in understanding the functions of miRNAs. By applying the May-Wigner theory used in foodweb studies, we show that i) weak repressions cumulatively enhance the stability of gene regulatory network (GRN), and ii) broad and weak repressions confer greater stability than a few strong ones. Transcriptome data show that yeast cells, which do not have miRNAs, use strong and non-specific mRNA degradation to stabilize their GRN; in contrast, human cells use miRNAs to increase degradation more modestly and selectively. Simulations indicate that miRNA repressions should be distributed broadly to >25% of mRNAs, in agreement with observations. As predicted, extremely highly expressed genes are avoided and transcription factors are preferred by miRNAs. In conclusion, the diffuse repression by miRNAs is likely a system-level strategy for enhancing GRN stability. This stability control may be the mechanistic basis of “canalization” (i.e., developmental homeostasis within each species), sometimes hypothesized to be a main function of miRNAs.

Optimal Process Architectures for Distributed Design Using a Social Network Model

2012 ◽  
Author(s):  
Peter Cormier ◽  
Erich Devendorf ◽  
Kemper Lewis
Keyword(s):  
Genetic Algorithm ◽  
Social Network ◽  
Design Process ◽  
Network Theory ◽  
Solution Process ◽  
Design System ◽  
Optimal Order ◽  
Distributed Design ◽  
Theory Approach ◽  
Design Systems

Distributed design systems fundamentally preserve individual design subsystem secrecy by limiting communication across subsystems. The natural secrecy of distributed design makes it difficult for design process managers to determine the appropriate order of subsystems in the design process. In this paper, we discuss a social network theory based heuristic to prescribe the optimal order of design subsystems. We call the order of the design subsystems process architecture and we leverage concepts like ‘distance,’ ‘bridging,’ and degree centrality’ to analyze the aggregate design system and identify preferable solution process architectures. Our network theory approach only requires a manager to know which subsystems share design information. We distinguish this research from previous work by empirically validating the heuristic against a genetic algorithm for 80 randomly generated distributed design systems. The heuristic performs well against the genetic algorithm and beats it in the majority of cases. Moreover, it does so without requiring any function evaluations.

Examining Interactions Between Solution Architecture and Designer Mistakes

2010 ◽  
Author(s):  
Erich Devendorf ◽  
Kemper Lewis
Keyword(s):  
Design Process ◽  
Optimization Problem ◽  
Solution Process ◽  
Unintended Consequences ◽  
Convergence Time ◽  
Distributed Design ◽  
Damping Properties ◽  
Process Architecture ◽  
The Impact

When designing complex systems, it is often the case that a design process is subjected to a variety of unexpected inputs, interruptions, and changes. These disturbances can create unintended consequences including changes to the design process architecture, the planned design responsibilities, or the design objectives and requirements. In this paper a specific type of design disturbance, mistakes, is investigated. The impact of mistakes on the convergence time of a distributed multi-subsystem optimization problem is studied for several solution process architectures. A five subsystem case study is used to help understand the ability of certain architectures to handle the impact of the mistakes. These observations have led to the hypothesis that selecting distributed design architectures that minimize the number of iterations to propagate mistakes can significantly reduce their impact. It is also observed that design architectures that converge quickly tend to have these same error damping properties. Considering these observations when selecting distributed design architectures can passively reduce the impact of mistakes.

Quantifying the Convergence Time of Distributed Design Processes

2011 ◽  
Author(s):  
Erich Devendorf ◽  
Kemper Lewis
Keyword(s):  
Systems Design ◽  
Discrete Systems ◽  
Product Development Process ◽  
Convergence Time ◽  
Distributed Design ◽  
Equilibrium Solutions ◽  
Acceptable Solution ◽  
Design Processes ◽  
Process Architecture ◽  
Number Of Iterations

Time is an asset of critical importance in the design process and it is desirable to reduce the amount of time spent developing products and systems. Design is an iterative activity and a significant portion of time spent in the product development process is consumed by design engineers iterating towards a mutually acceptable solution. Therefore, the amount of time necessary to complete a design can be shortened by reducing the time required for design iterations or by reducing the number of iterations. The focus of this paper is on reducing the number of iterations required to converge to a mutually acceptable solution in distributed design processes. In distributed design, large systems are decomposed into smaller, coupled design problems where individual designers have control over local design decisions and seek to satisfy their own individual objectives. The number of iterations required to reach equilibrium solutions in distributed design processes can vary depending on the starting location and the chosen process architecture. We investigate the influence of process architecture on the convergence behavior of distributed design systems. This investigation leverages concepts from game theory, classical controls and discrete systems theory to develop a transient response model. As a result, we are able to evaluate process architectures without carrying out any solution iterations.

Examining the Impact of Aggregated Design Impulses on Process Architecture in Distributed Design

2013 ◽  
Author(s):  
Sourobh Ghosh ◽  
Erich Devendorf ◽  
Kemper Lewis
Keyword(s):  
Complex Systems ◽  
Design Process ◽  
Transient Response ◽  
Design System ◽  
Distributed Design ◽  
Slow Convergence ◽  
Stochastic Inputs ◽  
Process Architecture ◽  
The Impact

During the design of complex systems, a design process may be subjected to stochastic inputs, interruptions, and changes. These design impulses can have a significant impact on the transient response and converged equilibrium for the design system. We distinguish this research by focusing on the interactions between local and architectural impulses in the form of designer mistakes and dissolution, division, and combination impulses, respectively. We find that local impulses tend to slow convergence but systems subjected to dissolution/division impulses still favor parallel arrangements. The strategy to mitigate combination impulses is unaffected by the presence of local impulses.

Are We There Yet? Investigating the Role of Design Process Architecture in Convergence Time

2009 ◽  
Author(s):  
Erich Devendorf ◽  
Kemper Lewis
Keyword(s):  
Design Process ◽  
Parallel Architecture ◽  
Convergence Time ◽  
Distributed Design ◽  
Theoretic Approach ◽  
Equilibrium Solutions ◽  
Design Variables ◽  
Decentralized Design ◽  
Time Required ◽  
Process Architecture

In distributed design individual designers have local control over design variables and seek to minimize their own individual objectives. The amount of time required to reach equilibrium solutions in decentralized design can vary based on the design process architecture chosen. There are two primary design process architectures, sequential and parallel, and a number of possible combinations of these architectures. In this paper a game theoretic approach is developed to determine the time required for a parallel and sequential architecture to converge to a solution for a two designer case. The equations derived solve for the time required to converge to a solution in closed form without any objective function evaluations. This result is validated by analyzing a distributed design case study. In this study the equations accurately predict the convergence time for a sequential and parallel architecture. A second validation is performed by analyzing a large number of randomly generated two designer systems. The approach in this case successfully predicts convergence within 3 iterations for nearly 98% of the systems analyzed. The remaining 2% highlight one of the approach’s weaknesses; it is susceptible to numerically ill conditioned problems. Understanding the rate at which distributed design problems converge is of key importance when determining design architectures. This work begins the investigation with a two designer case and lays the groundwork to expand to larger design systems with multiple design variables.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

Design of Electrostatic Precipitator Power System Based on Auto Disturbance Rejection Controller

2013 ◽  
Vol 846-847 ◽  
pp. 190-194
Author(s):  
Shu Jun Yin ◽  
Xue Ren Li ◽  
Ji Geng Luo
Keyword(s):  
Power Supply ◽  
Disturbance Rejection ◽  
Power Supply System ◽  
Electrostatic Precipitator ◽  
Supply System ◽  
System Stability ◽  
Engineering Practice ◽  
Single Chip ◽  
High Voltage Power Supply ◽  
The Stability

The paper designs a three-phase high voltage power supply system based on active disturbance rejection controller which make single-chip microcomputer ATmega128 as the main control chip and the system improve the stability and control precision of dust removing power. Engineering practice shows that, the DC power supply system has the advantages of convenient operation, high work efficiency, system stability.

scholarly journals Modelling of the Power Interface of the Digital-Physical Hybrid Simulation System of a VSC-HVDC Based on Virtual Resistance Compensation

Electronics ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 333
Author(s):  
Jian Le ◽  
Hao Zhang ◽  
Cao Wang ◽  
Xingrui Li ◽  
Jiangfeng Zhu
Keyword(s):  
Current Source ◽  
Hybrid Simulation ◽  
Simulation System ◽  
System Stability ◽  
Interface Model ◽  
Simulation Accuracy ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
The Stability ◽  
Stability And Accuracy

To enhance the stability and accuracy of the digital-physical hybrid simulation system of a modular multilevel converter-based high voltage direct current (MMC-HVDC) system, this paper presents an improved power interface modeling algorithm based on ideal transformer method (ITM). By analyzing the stability condition of a hybrid simulation system based on the ITM model, the current of a so-called virtual resistance is added to the control signal of the controlled current source in the digital subsystem, and the stability of the hybrid simulation system with the improved power interface model is analyzed. The value of the virtual resistance is optimized by comprehensively considering system stability and simulation precision. A two-terminal bipolar MMC-HVDC simulation system based on the proposed power interface model is established. The comparisons of the simulation results verify that the proposed method can effectively improve the stability of the hybrid simulation system, and at the same time has the advantages of high simulation accuracy and easy implementation.

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