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.

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.

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.

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.

scholarly journals Increasing sulfate levels show a differential impact on synthetic communities comprising different methanogens and a sulfate reducer

2019 ◽  
Vol 16 (154) ◽  
pp. 20190129 ◽  
Author(s):  
Jing Chen ◽  
Matthew J. Wade ◽  
Jan Dolfing ◽  
Orkun S. Soyer
Keyword(s):  
Microbial Communities ◽  
Methane Production ◽  
System Stability ◽  
Sulfate Reducer ◽  
Differential Impact ◽  
Sulfate Reducers ◽  
Hydrogenotrophic Methanogens ◽  
The Stability ◽  
The Impact

Methane-producing microbial communities are of ecological and biotechnological interest. Syntrophic interactions among sulfate reducers and aceto/hydrogenotrophic and obligate hydrogenotrophic methanogens form a key component of these communities, yet, the impact of these different syntrophic routes on methane production and their stability against sulfate availability are not well understood. Here, we construct model synthetic communities using a sulfate reducer and two types of methanogens representing different methanogenesis routes. We find that tri-cultures with both routes increase methane production by almost twofold compared to co-cultures and are stable in the absence of sulfate. With increasing sulfate, system stability and productivity decreases and does so faster in communities with aceto/hydrogenotrophic methanogens despite the continued presence of acetate. We show that this is due to a shift in the metabolism of these methanogens towards co-utilization of hydrogen with acetate. These findings indicate the important role of hydrogen dynamics in the stability and productivity of syntrophic communities.

scholarly journals Impedance Aggregation Method of Multiple Wind Turbines and Accuracy Analysis

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2035 ◽  
Author(s):  
Liang Chen ◽  
Heng Nian ◽  
Yunyang Xu
Keyword(s):  
Stability Analysis ◽  
Reference Frame ◽  
Wind Turbines ◽  
Power Distribution ◽  
Wind Farm ◽  
System Level ◽  
Small Signal ◽  
Impedance Model ◽  
The Stability ◽  
The Impact

The sequence domain impedance modeling of wind turbines (WTs) has been widely used in the stability analysis between WTs and weak grids with high line impedance. An aggregated impedance model of the wind farm is required in the system-level analysis. However, directly aggregating WT small-signal impedance models will lead to an inaccurate aggregated impedance model due to the mismatch of reference frame definitions among different WT subsystems, which may lead to inaccuracy in the stability analysis. In this paper, we analyze the impacts of the reference frame mismatch between a local small-signal impedance model and a global one on the accuracy of aggregated impedance and the accuracy of impedance-based stability analysis. The results revealed that the impact is related to the power distribution of the studied network. It was found that that the influence of mismatch on stability analysis became subtle when subsystems were balanced loaded. Considering that balanced loading is a common configuration of the practical application, direct impedance aggregation by local small-signal models can be applied due to its acceptable accuracy.

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.

scholarly journals Information and Statistical Efforts of Selected Safety Network Institutions in the Area of Financial System Stability

2019 ◽  
pp. 143-157
Author(s):  
Piotr Komorowski ◽  
Dariusz Filip
Keyword(s):  
Public Good ◽  
Statistical Data ◽  
Financial System ◽  
System Stability ◽  
Main Role ◽  
Overall Stability ◽  
System Information ◽  
The Stability ◽  
The Impact

Financial system stability is considered a public good. The main role of the financial safety network is to stabilise the system. Information and statistical activities of institutions which belong to the safety network are the tools which may improve the stability. We need to stress that most decisions are based on information, in particular decisions on investment or speculation, hence by providing information and statistical data these institutions indirectly enhance the overall stability of the system. An overview and analysis of selected studies addressing financial system stability helped the authors draw theoret- ical and practical conclusions as to the stability itself and the impact of information and statistics upon its improvement.

scholarly journals The Impact of Service and Channel Integration on the Stability and Complexity of the Supply Chain

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-27 ◽  
Author(s):  
Jianheng Zhou ◽  
Xingli Chen
Keyword(s):  
Supply Chain ◽  
Dynamic Models ◽  
Stackelberg Game ◽  
Profit Sharing ◽  
System Stability ◽  
Stable Region ◽  
Channel Integration ◽  
Profit Allocation ◽  
The Stability ◽  
The Impact

This paper constructs a supply chain consisting of a manufacturer and a retailer. Considering channel integration and service cooperation, two dynamic Stackelberg game models are established: one without unit profit allocation M and the other one with unit profit allocation Mε. In two dynamic models, we analyze the influence of relevant parameters on the stability and complexity of the dynamic system and system profit by nonlinear system theory and numerical simulation. We find that the higher adjustment parameters can cause the system to lose stability, showing double period bifurcation or wave-shape chaos. The stable region becomes larger with increase in service value and value of unit profit sharing. Besides, when the system is in chaotic state, we find that the profit of the system will fluctuate or even decline sharply; however, keeping the parameters in a certain range is helpful in maintaining the system stability and is conducive to decision-makers to obtain steady profits. In order to control the chaos phenomenon, the state feedback method is employed to control the chaotic system well. This study provides some valuable significance to supply chain managers in channel integration and service cooperation.

scholarly journals Modeling the stability of the financial system of the country

2019 ◽  
Vol 65 ◽  
pp. 04015
Author(s):  
Valdemar Vitlinskyi ◽  
Liubov Makhanets
Keyword(s):  
Public Finance ◽  
Financial System ◽  
System Stability ◽  
Financial Security ◽  
State Institutions ◽  
The Public ◽  
The Stability ◽  
The Impact

The security of the public finance sector of Ukraine requires monitoring of indicators of the stability of the financial system of the country, as well as modeling the impact of these indicators on the country’s financial security. It is shown that the stability of the financial system of the economy can be checked with the help of the provisions of econophysics. The concept of equilibrium is using to determine stability. The influence of factors on the level of financial security, which is one of the aspects of assessing the stability of the financial system of Ukraine is able to evaluate by simulation. The model of the financial system stability of the country is constructed in the paper. This research can serve as the basis for the adoption by the relevant state institutions of sound decisions on ensuring the stability of the financial system of Ukraine.

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.

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