scholarly journals An introduction to the topological derivative

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Samuel Amstutz
Keyword(s):  
Simple Model ◽  
Design Methodology ◽  
Topological Derivative ◽  
Modern Approach ◽  
Content Type ◽  
Adjoint State ◽  
Topological Derivatives ◽  
State Technique ◽  
Didactic Presentation

PurposeThis paper provides a self-contained introduction to the mathematical aspects of the topological derivative.Design/methodology/approachFull justifications are given on simple model problems following a modern approach based on the averaged adjoint state technique. Extensions are discussed in relation with the literature on the field.FindingsClosed expressions of topological derivatives are obtained and commented.Originality/valueSeveral cases are covered in a unified and didactic presentation. Some elements of proof are novel.

Topological derivatives via one-sided derivative of parametrized minima and minimax

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Michel C. Delfour
Keyword(s):  
Directional Derivative ◽  
Topological Derivative ◽  
Dimensional Euclidean Space ◽  
Objective Functions ◽  
State Equations ◽  
Content Type ◽  
Adjoint State ◽  
Topological Derivatives ◽  
Wide Range ◽  
The One

PurposeThe object of the paper is to illustrate how to obtain the topological derivative as a semidifferential in a general and practical mathematical setting for d-dimensional perturbations of a bounded open domain in the n-dimensional Euclidean space.Design/methodology/approachThe underlying methodology uses mathematical notions and powerful tools with ready to check assumptions and ready to use formulas via theorems on the one-sided derivative of parametrized minima and minimax.FindingsThe theory and the examples indicate that the methodology applies to a wide range of problems: (1) compliance and (2) state constrained objective functions where the coupled state/adjoint state equations appear without a posteriori substitution of the adjoint state.Research limitations/implicationsDirect approach that considerably simplifies the analysis and computations.Originality/valueIt was known that the shape derivative was a differential. But the topological derivative is only a semidifferential, that is, a one-sided directional derivative, which is not linear with respect to the direction, and the directions are d-dimensional bounded measures.

Representative bubbles and deleveraging

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Francesco Strati
Keyword(s):  
Simple Model ◽  
Theoretical Approach ◽  
Design Methodology ◽  
Sufficient Conditions ◽  
Sufficient Condition ◽  
Demand Side ◽  
Content Type ◽  
Real Effects ◽  
Crowd Out ◽  
Practical Implications

PurposeThe causes for the formation of a bubble in the collateral market when agents are provided with homogeneous expectations are explored. This bubbly dynamics will define a sufficient condition for deleveraging.Design/methodology/approachTheoretical approach with neutral deleveraging.FindingsFindings of the study are defined sufficient conditions for a behavioral rational bubble's formation in a market of collateral and the subsequent deleveraging. The crowd-in effect of the representative bubble is caused by errors in extrapolating information and thus by representativeness, while the crowd-out effect of deleveraging is set off by reverting to a rational heuristic.Research limitations/implicationsThe limit is that it is a homogeneous expectations approach, the implication is that cannot be rational speculation.Practical implicationsEven in a simple model of homogeneous expectations a bubble may arise with serious effect on the demand side: models that detect just rational mispricings cannot account for behavioral components that have financial and real effects.Originality/valueThe paper defines how deleveraging may occur even in case of homogeneous expectations. The latter should not be seen just as a limit but also as a signal of the importance of being aware of behavioral components.

scholarly journals On the justification of topological derivative for wave-based qualitative imaging of finite-sized defects in bounded media

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Marc Bonnet
Keyword(s):  
Design Methodology ◽  
Bessel Functions ◽  
Order Term ◽  
True Anomaly ◽  
Single Measurement ◽  
Bounded Linear ◽  
Content Type ◽  
Focusing Effect ◽  
Decay Properties ◽  
Topological Derivatives

PurposeThis work contributes to the general problem of justifying the validity of the heuristic that underpins medium imaging using topological derivatives (TDs), which involves the sign and the spatial decay away from the true anomaly of the TD functional. The author considers here the identification of finite-sized (i.e. not necessarily small) anomalies embedded in bounded media and affecting the leading-order term of the acoustic field equation.Design/methodology/approachTD-based imaging functionals are reformulated for analysis using a suitable factorization of the acoustic fields, which is facilitated by a volume integral formulation. The three kinds of TDs (single-measurement, full-measurement and eigenfunction-based) studied in this work are given expressions whose structure allows to establish results on their sign and decay properties. The latter are obtained using analytical methods involving classical identities on Bessel functions and Legendre polynomials, as well as asymptotic approximations predicated on spatial scaling assumptions.FindingsThe sign component of the TD imaging heuristic is found to be valid for multistatic experiments and if the sought anomaly satisfies a bound (on a certain operator norm) involving its geometry, its contrast and the operating frequency. Moreover, upon processing the excitation and data by applying suitably-defined bounded linear operatirs to them, the magnitude component of the TD imaging heuristic is proved under scaling assumptions where the anomaly is small relative to the probing region, the latter being itself small relative to the propagation domain. The author additionally validates both components of the TD imaging heuristic when the probing excitation is taken as an eigenfunction of the source-to-measurement operator, with a focusing effect analogous to that achieved in time-reversal based methods taking place. These findings extend those of earlier studies to the case of finite-sized anomalies embedded in bounded media.Originality/valueThe originality of the paper lies in the theoretical justifications of the TD-based imaging heuristic for finite-sized anomalies embedded in bounded media.

An experimental/numerical hydrothermal analysis on natural convection and TiO2-SiO2/W-EG nanofluid’s properties in a hollow/finned cavity

2020 ◽  
Vol 30 (10) ◽  
pp. 4563-4581 ◽  
Author(s):  
Mahshid Zaresharif ◽  
Fatemeh Zarei ◽  
Ali Mohammad Ranjbar ◽  
Loke Kok Foong ◽  
David Ross
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Design Methodology ◽  
Heat Transfer Performance ◽  
Square Cavity ◽  
Modern Approach ◽  
Content Type ◽  
Different Temperatures ◽  
The Stability ◽  
Boltzmann Method

Purpose This paper aims to provide an experimental/numerical analysis of free convection within a hollow/finned cavity. Design/methodology/approach The hollow square cavity is equipped with eight active fins which have a similar configuration and different temperatures. Furthermore, four different thermal arrangements are considered to determine the order of temperature for each fin. The coupled lattice Boltzmann method is used, which not only maintains the considerable advantages of standard lattice Boltzmann method such as accuracy but also enhances the stability of this method. Findings The cavity is filled with TiO2-SiO2/Water-Ethylene Glycol nanofluid. The thermal conductivity and dynamic viscosity of nanofluid are experimentally measured using high-precision devices in six concentrations of the nanoparticle. In this study, some main parameters, including a range of Rayleigh number (103 < Ra < 106), the concentration of nanofluid (0.5 to 3 Vol.%) and thermal arrangements of fins, are considered. The effects of these main parameters on the flow, isotherms, heat transfer performance and entropy generation are studied. Originality/value The originality of this paper is combining the numerical simulation (lattice Boltzmann method) using a modern approach with experimental observations of nanofluid’s properties.

Social learning augmented by social media: creating better organizations for a better world

2014 ◽  
Vol 28 (6) ◽  
pp. 6-8
Author(s):  
Marcia L. Conner
Keyword(s):  
Social Media ◽  
Social Learning ◽  
Design Methodology ◽  
Education Programs ◽  
Modern Approach ◽  
Content Type ◽  
Social Technologies ◽  
New Knowledge ◽  
Learning Labs ◽  
New Type

Purpose – Social media provides a modern approach to working and learning with people across vast distances as easily as if they were side by side. The new tools foster a new type of social learning, offering leaders an opportunity to transform their organizations into rich learning labs where new knowledge and innovative practices emerge in real-time. Design/methodology/approach – Based on my book published in 2010, and the work I have done with more than 100 companies on social media’s use for fostering social learning. Findings – Social technologies should be used to replace outmoded education programs with more effective and mobile means. With these tools, learners can reframe learning from a passive activity done to learners to an active and very human activity that enables people to build upon their individual and collective potential. Originality/value – Written for this publication, yet based on the learnings since and research done originally for The New Social Learning.

Global environmental policies with innovation spillovers

2019 ◽  
Vol 30 (4) ◽  
pp. 833-850 ◽  
Author(s):  
Manoj Kumar
Keyword(s):  
Simple Model ◽  
Fuel Economy ◽  
Design Methodology ◽  
Environmental Problem ◽  
Fuel Efficiency ◽  
Environmental Policies ◽  
The Other ◽  
Content Type ◽  
Fuel Tax ◽  
Global Environmental

Purpose The purpose of this paper is to explore automobile fuel efficiency policies in the presence of two externalities: a global environmental problem and international innovation spillovers. Design/methodology/approach Using a simple model with two regions, the authors show that both a fuel tax and a tax on vehicles based on their fuel economy rating are needed to decentralize the first best. Findings If standards are used instead of taxes, the authors find that spillovers may alleviate free-riding. Under some conditions, a strict standard in one region may favor the adoption of a strict standard in the other one. Originality/value The authors also show that if policies are not coordinated between regions, the resulting gas taxes will be set too low and each region will use the tax on fuel rating to reduce the damage caused by foreign drivers.

scholarly journals Vulnerable adults in police custody

2019 ◽  
Vol 22 (1) ◽  
pp. 5-8
Author(s):  
Ian Cummins
Keyword(s):  
Design Methodology ◽  
Research Literature ◽  
Police Custody ◽  
England And Wales ◽  
Content Type ◽  
Increased Risk ◽  
Vulnerable Adults

Purpose The purpose of this paper is to discuss the recent National Appropriate Adult Network (NAAN) report on the role of the appropriate adult. Design/methodology/approach This paper is based on the NAAN report and a review of relevant policy and research literature. Findings There to Help 2 highlights that there are still significant gaps in the provision of appropriate adult schemes across England and Wales. These gaps potentially place vulnerable adults at increased risk. Originality/value This paper is a review of recent research.

Co-workers’ perceptions of and reactions to employee’s involuntary demotion

2019 ◽  
Vol 41 (4) ◽  
pp. 740-757 ◽  
Author(s):  
Sophie Hennekam ◽  
Subramaniam Ananthram ◽  
Steve McKenna
Keyword(s):  
Design Methodology ◽  
Emotional Responses ◽  
Emotional Reaction ◽  
Content Type ◽  
Informational Justice ◽  
Behavioural Responses ◽  
Behavioural Reaction ◽  
Three Stages ◽  
Depth Interviews ◽  
The Way

Purpose The purpose of this paper is to investigate how individuals perceive and react to the involuntary demotion of a co-worker in their organisation. Design/methodology/approach The authors draw on 46 semi-structured in-depth interviews (23 dyads) with co-workers of demoted individuals. Findings The findings suggest that an individual’s observation of the demotion of a co-worker has three stages: their perception of fairness, their emotional reaction and their behavioural reaction. The perception of fairness concerned issues of distributive, procedural, interpersonal and informational justice. The emotional responses identified were feelings of disappointment/disillusion, uncertainty, vulnerability and anger. Finally, the behavioural reactions triggered by their emotional responses included expressions of voice, loyalty, exit and adaptation. Originality/value Perceptions of (in)justice perpetrated on others stimulate emotional and behavioural responses, which impacts organisational functioning. Managers should therefore pay attention to the way a demotion is perceived, not only by those directly concerned, but also by co-workers as observers.

Consumer value creation through WhatsApp use

2019 ◽  
Vol 32 (4) ◽  
pp. 455-471
Author(s):  
Jorge Cruz-Cárdenas ◽  
Jorge Guadalupe-Lanas ◽  
Ekaterina Zabelina ◽  
Andrés Palacio-Fierro ◽  
Margarita Velín-Fárez ◽  
...  
Keyword(s):  
Latin American ◽  
Value Creation ◽  
Emotional Support ◽  
Design Methodology ◽  
Instant Messaging ◽  
Role Performance ◽  
Content Type ◽  
Consumer Value ◽  
Depth Interviews ◽  
Practical Implications

Purpose The purpose of this paper is to understand in-depth how consumers create value in their lives using WhatsApp, the leading mobile instant messaging (MIM) application. Design/methodology/approach The study adopts the perspective of customer-dominant logic (CDL) and uses a qualitative multimethod design involving 3 focus groups and 25 subsequent in-depth interviews. The research setting was Ecuador, a Latin American country. Findings Analysis and interpretation of the participants’ stories made it possible to identify and understand the creation of four types of value: maintaining and strengthening relationships; improving role performance; emotional support; and entertainment and fun. In addition, the present study proposes a conceptual model of consumer value creation as it applies to MIM. Practical implications Understanding the way consumers create value in their lives using MIM is important not only for organizations that offer MIM applications, but also for those companies that develop other applications for mobile phones or for those who wish to use MIM as an electronic word-of-mouth vehicle. Originality/value The current study is one of the first to address the topic of consumer behavior in the use of technologies from the perspective of CDL; this perspective enables an integrated qualitative vision of value creation in which the consumer is the protagonist.

scholarly journals Advantages and potential challenges of data management in e-maintenance

2019 ◽  
Vol 25 (3) ◽  
pp. 378-396 ◽  
Author(s):  
Arian Razmi-Farooji ◽  
Hanna Kropsu-Vehkaperä ◽  
Janne Härkönen ◽  
Harri Haapasalo
Keyword(s):  
Data Management ◽  
Design Methodology ◽  
Management Practices ◽  
Future Research ◽  
Conceptual Approach ◽  
Content Type ◽  
Different Types ◽  
Maintenance Systems ◽  
Industry Leader ◽  
Practical Implications

Purpose The purpose of this paper is twofold: first, to understand data management challenges in e-maintenance systems from a holistically viewpoint through summarizing the earlier scattered research in the field, and second, to present a conceptual approach for addressing these challenges in practice. Design/methodology/approach The study is realized as a combination of a literature review and by the means of analyzing the practices on an industry leader in manufacturing and maintenance services. Findings This research provides a general understanding over data management challenges in e-maintenance and summarizes their associated proposed solutions. In addition, this paper lists and exemplifies different types and sources of data which can be collected in e-maintenance, across different organizational levels. Analyzing the data management practices of an e-maintenance industry leader provides a conceptual approach to address identified challenges in practice. Research limitations/implications Since this paper is based on studying the practices of a single company, it might be limited to generalize the results. Future research topics can focus on each of mentioned data management challenges and also validate the applicability of presented model in other companies and industries. Practical implications Understanding the e-maintenance-related challenges helps maintenance managers and other involved stakeholders in e-maintenance systems to better solve the challenges. Originality/value The so-far literature on e-maintenance has been studied with narrow focus to data and data management in e-maintenance appears as one of the less studied topics in the literature. This research paper contributes to e-maintenance by highlighting the deficiencies of the discussion surrounding the perspectives of data management in e-maintenance by studying all common data management challenges and listing different types of data which need to be acquired in e-maintenance systems.

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