Use of a Trophic Structure Test Bed to Validate a New Systems-of-Systems Resilience Metric

2020 ◽  
Author(s):  
Bryan C. Watson ◽  
Sanaya Kriplani ◽  
Marc J. Weissburg ◽  
Bert Bras
Keyword(s):  
Network Structure ◽  
Trophic Structure ◽  
Design Tool ◽  
Natural Ecosystem ◽  
Test Bed ◽  
Systems Of Systems ◽  
Network Characteristics ◽  
Biologically Inspired Design ◽  
Future Work ◽  
Structure Test

Abstract Systems of Systems (SoS) combine complex systems such as financial, transportation, energy, and healthcare systems to provide greater functionality. A failure in a constituent system, however, can render the entire SoS ineffective by causing cascading faults. One method to prevent constituent faults from compromising SoS performance is to increase the SoS’s “resilience,” a measure of the SoS’s ability to cope with these faults and efficiently recover. Attempts to engineer improved resilience require a metric to measure resilience across different SoS architectures (network arrangements). In a previous work, the System of System Resilience Metric (SoSRM) was presented as a possible solution, but this new metric requires additional testing. This work examines the key question: “How can natural ecosystem characteristics be used to validate the SoSRM metric?” We hypothesize that the analysis of a test bed of generic ecosystems will produce SoSRM values that will positively correlate with a triangular trophic structure (wide base), validating SoSRM as a useful design metric. First principles for test bed creation are presented including biodiversity, trophic structure, and the role of detritus. SoSRM is measured for 31 case studies in a trophic structure test bed. Ecosystem network structure is quantified with graph theory. SoSRM correlates as expected with ecosystem network structure (r2 = .5016, n = 31), thus providing a validation of SoSRM as a design tool. As a final check, tests are conducted to ensure SoSRM is independent of trivial network characteristics (i.e. the number of nodes or links). By validating SoSRM, we provide a foundation for future work that focuses on increasing SoS resilience with biologically inspired design heuristics.

Use of a Trophic Structure Test Bed to Validate a New Systems-of-Systems Resilience Metric

2021 ◽  
Author(s):  
Bryan Watson ◽  
Sanaya Kriplani ◽  
Marc Weissburg ◽  
Bert Bras
Keyword(s):  
Trophic Structure ◽  
Test Bed ◽  
Systems Of Systems ◽  
Structure Test

Use of a Trophic Structure Test Bed to Validate a New Systems-of-Systems Resilience Metric

2021 ◽  
Author(s):  
Bryan Watson ◽  
Sanaya Kriplani ◽  
Marc Weissburg ◽  
Bert Bras
Keyword(s):  
Trophic Structure ◽  
Test Bed ◽  
Systems Of Systems ◽  
Structure Test

A case for multi-level optimisation in aeronautical design

1999 ◽  
Vol 103 (1028) ◽  
pp. 481-485 ◽  
Author(s):  
G. M. Robinson ◽  
A. J. Keane
Keyword(s):  
Computational Cost ◽  
Design Tool ◽  
Test Bed ◽  
Design Environment ◽  
Aircraft Wing ◽  
Computing Power ◽  
Transport Aircraft ◽  
Estimation Algorithms ◽  
Multi Level ◽  
Optimisation Algorithms

Abstract This paper discusses how the inevitable limitations of computing power available to designers has restricted adoption of optimisation as an essential design tool. It is argued that this situation will continue until optimisation algorithms are developed which utilise the range of available analysis methods in a manner more like human designers. The concept of multi-level algorithms is introduced and a case made for their adoption as the way forward. The issues to be addressed in the development of multi-level algorithms are highlighted. The paper goes on to discuss a system developed at Southampton University to act as a test bed for multi-level algorithms deployed on a realistic design task. The Southampton University multi-level wing design environment integrates drag estimation algorithms ranging from an empirical code to an Euler CFD code, covering a 150,000 fold difference in computational cost. A simple multi-level optimisation of a civil transport aircraft wing is presented.

scholarly journals Brain connectivity dynamics during social interaction reflect social network structure

2016 ◽  
Author(s):  
Ralf Schmälzle ◽  
Matthew Brook O’Donnell ◽  
Javier O. Garcia ◽  
Christopher N. Cascio ◽  
Joseph Bayer ◽  
...  
Keyword(s):  
Social Network ◽  
Social Exclusion ◽  
Network Structure ◽  
Mental States ◽  
Individual Variability ◽  
Friendship Networks ◽  
Imaging Data ◽  
Network Characteristics ◽  
Social Network Structure ◽  
Mentalizing System

AbstractSocial ties are crucial for humans. Disruption of ties through social exclusion has a marked effect on our thoughts and feelings; however, such effects can be tempered by broader social network resources. Here, we use functional magnetic resonance imaging data acquired from 80 male adolescents to investigate how social exclusion modulates functional connectivity within and across brain networks involved in social pain and understanding the mental states of others (i.e., mentalizing). Furthermore, using objectively logged friendship network data, we examine how individual variability in brain reactivity to social exclusion relates to the density of participants’ friendship networks, an important aspect of social network structure. We find increased connectivity within a set of regions previously identified as a mentalizing system during exclusion relative to inclusion. These results are consistent across the regions of interest as well as a whole-brain analysis. Next, examining how social network characteristics are associated with task-based connectivity dynamics, participants who showed greater changes in connectivity within the mentalizing system when socially excluded by peers had less dense friendship networks. This work provides novel insight to understand how distributed brain systems respond to social and emotional challenges, and how such brain dynamics might vary based on broader social network characteristics.

Human Rights and Transnational Advocacy Networks

2016 ◽  
Author(s):  
Amanda Murdie ◽  
Marc Polizzi
Keyword(s):  
Human Rights ◽  
Transnational Advocacy ◽  
Local Data ◽  
Network Characteristics ◽  
Transnational Advocacy Networks ◽  
Advocacy Network ◽  
Political Networks ◽  
Human Rights Advocacy ◽  
Global And Local ◽  
Future Work

Human rights advocates have been argued to be working as part of a larger “network” of actors supporting the respect and security of individuals. However, until recently, much scholarship in this area has used “network” as a synonym for “connected actors” instead of examining the network characteristics of advocacy actors and the ways in which the nature of the advocacy network could influence human rights outcomes. This chapter examines the growing literature that focuses on human rights advocacy using network theory and methodologies. It outlines both global and local data collection efforts and the state of the literature and addresses how this literature has drawn on the larger political networks literature. It concludes with a call for future work on how the network characteristics of advocacy actors influences both which human rights issues receive international attention and whether this attention translates into improvements in human rights practices on the ground.

scholarly journals Industrial Feedback on Implementing Functional Decomposition Design Processes for Reliability and Functional Safety

2018 ◽  
Vol 223 ◽  
pp. 01023
Author(s):  
Matt Pallaver ◽  
Ahed Qaddoura ◽  
Sung-hee Do
Keyword(s):  
System Development ◽  
Implementation Process ◽  
Axiomatic Design ◽  
Lessons Learned ◽  
Design Tool ◽  
Functional Requirements ◽  
Interface Elements ◽  
Systems Of Systems ◽  
Functional Decomposition ◽  
Design Processes

The value of Axiomatic Design functional decomposition as a design analysis point tool has been widely reported. This paper reports on the implementation of functional decomposition design processes as a system design tool on 23 industrial projects over a 5 year period with product development teams ranging from 6 to 35 engineers. The products developed were systems of systems with mechanical, electrical, firmware, software, and operational interface elements. Functional decompositions ranged from about 200 to 1600 Functional Requirements. A number of these projects are now in commercial production. This paper reviews the process definition and implementation process steps that evolved from these experiences. The paper then reports on the implementation lessons learned and the value propositions noted. Conclusions and recommendations are made. The experiences demonstrated that functional requirement decomposition processes aid in achieving on-time, on-cost and on-specification project development targets. The authors propose this paper summarizes the “Endgame” design process impact that axiomatic design can reasonably expect in industry design practices for system development.

scholarly journals The Association Between Internet Addiction and Anxiety in Nursing Students: A Network Analysis

2021 ◽  
Vol 12 ◽  
Author(s):  
Hong Cai ◽  
Hai-Tao Xi ◽  
Fengrong An ◽  
Zhiwen Wang ◽  
Lin Han ◽  
...  
Keyword(s):  
Nursing Students ◽  
Network Analysis ◽  
Network Structure ◽  
Internet Addiction ◽  
Internet Use ◽  
Anxiety Symptoms ◽  
Network Characteristics ◽  
School Grades ◽  
Region Of Residence ◽  
Urban Rural

Background: Nursing students who suffer from co-occurring anxiety experience added difficulties when communicating and interacting with others in a healthy, positive, and meaningful way. Previous studies have found strong positive correlations between Internet addiction (IA) and anxiety, suggesting that nursing students who report severe IA are susceptible to debilitating anxiety as well. To date, however, network analysis (NA) studies exploring the nature of association between individual symptoms of IA and anxiety have not been published.Objective: This study examined associations between symptoms of IA and anxiety among nursing students using network analysis.Methods: IA and anxiety symptoms were assessed using the Internet Addiction Test (IAT) and the Generalized Anxiety Disorder Screener (GAD-7), respectively. The structure of IA and anxiety symptoms was characterized using “Strength” as a centrality index in the symptom network. Network stability was tested using a case-dropping bootstrap procedure and a Network Comparison Test (NCT) was conducted to examine whether network characteristics differed on the basis of gender and by region of residence.Results: A total of 1,070 nursing students participated in the study. Network analysis showed that IAT nodes, “Academic decline due to Internet use,” “Depressed/moody/nervous only while being off-line,” “School grades suffer due to Internet use,” and “Others complain about your time spent online” were the most influential symptoms in the IA-anxiety network model. Gender and urban/rural residence did not significantly influence the overall network structure.Conclusion: Several influential individual symptoms including Academic declines due to Internet use, Depressed/moody/nervous only while being off-line, School grades suffering due to Internet use and Others complain about one's time spent online emerged as potential targets for clinical interventions to reduce co-occurring IA and anxiety. Additionally, the overall network structure provides a data-based hypothesis for explaining potential mechanisms that account for comorbid IA and anxiety.

scholarly journals Rethinking the Role of the Angular Gyrus in Remembering the Past and Imagining the Future: The Contextual Integration Model

2017 ◽  
Vol 24 (4) ◽  
pp. 342-352 ◽  
Author(s):  
Siddharth Ramanan ◽  
Olivier Piguet ◽  
Muireann Irish
Keyword(s):  
Contextual Information ◽  
Angular Gyrus ◽  
Test Bed ◽  
Medial Temporal Lobes ◽  
Integration Model ◽  
The Past ◽  
Contextual Integration ◽  
Core Elements ◽  
Future Work

Despite consistent activation on tasks of episodic memory, the precise contribution of the left angular gyrus (AG) to mnemonic functions remains vigorously debated. Mounting evidence suggests that AG activity scales with subjective ratings of vividness and confidence in recollection, with further evidence pointing to its involvement during construction of detailed and coherent future simulations. Lesion studies, however, indicate that damage to the AG does not render patients amnesic on standard source and associative memory paradigms. To reconcile these findings, we present the Contextual Integration Model as a unifying framework that couches the mnemonic role of the AG in terms of multimodal integration and representation of contextual information across temporal contexts. Irrespective of whether one is remembering the past or constructing future or hypothetical scenarios, the Contextual Integration Model holds that the core elements of an event (i.e., the who, what, when, where) are bound within the medial temporal lobes while the multimodal details, which give rise to perceptually rich recollection, are integrated and represented in the AG. Building on previous work, the Contextual Integration Model therefore provides a comprehensive exposition of the mnemonic and constructive functions of the AG across temporal contexts, offering a novel test-bed for future work.

ON THE DETERMINANTS OF FIBRE THICKNESS AND FIBRIN NETWORK CHARACTERISTICS.

1987 ◽  
Author(s):  
C H Nair ◽  
G A Shah ◽  
D P Dhall
Keyword(s):  
Network Structure ◽  
Plasma Proteins ◽  
Antithrombin Iii ◽  
Network Development ◽  
Network Characteristics ◽  
Fibrin Network ◽  
Fibre Growth ◽  
Network Properties ◽  
Kinetics Of ◽  
Lower Tensile Strength

Spectacular differences are found between characteristics of networks developed in plasma and those developed in pure fibrinogen solution. Networks in plasma have thicker fibres, are more permeable and have lower tensile strength. In this investigation determinants of network structure under "hycio-logical conditions of clotting have been examined in an attempt to account for differences in network structure in plasma and in fibrinogen solution.Two independent variations of mass-length ratio ( µp and µr-.) from permeability and turbidity respectively were used. Effect of varying fibrinogen and thrombin concentrations and the effect of physiological concentrations of Antithrombin III, fibronectin, albumin, γ-globulin and platelet extract on fibrin network structure was examined.Fibrinogen and thrombin alter network characteristics through the modification of kinetics of network development.In these and several other studies it has been found that the kinetics of fibrin formation ultimately determine the final network structure through events preceding the appearance of visible fibrin. In separate experiments it was found that spectacular differences in network structure developed in plasma and fibrinogen were not entirely accounted for by alterations induced in network properties by albumin, y-globulin, fibronectin, ATIII and platelet extract.It is concluded that the final network structure is determined by kinetics of fibrin fibre growth and is highly responsive to the presence of plasma proteins and platelets.The findings may have fundamental applications to haemostasis and thrombosis.

scholarly journals A Large-Scale Comparative Study of Informal Social Networks in Firms

2021 ◽  
Author(s):  
Abigail Z. Jacobs ◽  
Duncan J. Watts
Keyword(s):  
Network Structure ◽  
Large Scale ◽  
Network Size ◽  
Emergent Properties ◽  
Network Data ◽  
Data Set ◽  
Network Characteristics ◽  
Individual Level ◽  
Industrial Sectors ◽  
Wide Range

Theories of organizations are sympathetic to long-standing ideas from network science that organizational networks should be regarded as multiscale and capable of displaying emergent properties. However, the historical difficulty of collecting individual-level network data for many (N ≫ 1) organizations, each of which comprises many (n ≫ 1) individuals, has hobbled efforts to develop specific, theoretically motivated hypotheses connecting micro- (i.e., individual-level) network structure with macro-organizational properties. In this paper we seek to stimulate such efforts with an exploratory analysis of a unique data set of aggregated, anonymized email data from an enterprise email system that includes 1.8 billion messages sent by 1.4 million users from 65 publicly traded U.S. firms spanning a wide range of sizes and 7 industrial sectors. We uncover wide heterogeneity among firms with respect to all measured network characteristics, and we find robust network and organizational variation as a result of size. Interestingly, we find no clear associations between organizational network structure and firm age, industry, or performance; however, we do find that centralization increases with geographical dispersion—a result that is not explained by network size. Although preliminary, these results raise new questions for organizational theory as well as new issues for collecting, processing, and interpreting digital network data. This paper was accepted by David Simchi-Levi, Special Issue of Management Science: 65th Anniversary.

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