Trefftz method in solving the pennes’ and single-phase-lag heat conduction problems with perfusion in the skin

2019 ◽  
Vol 30 (6) ◽  
pp. 3231-3246
Author(s):  
Krzysztof Grysa ◽  
Artur Maciag
Keyword(s):  
Linear Combination ◽  
Thermal Wave ◽  
Single Phase ◽  
Wave Attenuation ◽  
Initial Boundary ◽  
Approximate Solutions ◽  
Phase Lag ◽  
Content Type ◽  
Pennes Equation ◽  
First Time

Purpose The purpose of this paper is to derive the Trefftz functions (T-functions) for the Pennes’ equation and for the single-phase-lag (SPL) model (hyperbolic equation) with perfusion and then comparing field of temperature in a flat slab made of skin in the case when perfusion is taken into account, with the situation when a Fourier model is considered. When considering the process of heat conduction in the skin, one needs to take into account the average values of its thermal properties. When in biological bodies relaxation time is of the order of 20 s, the thermal wave propagation appears. The initial-boundary problems for Pennes’ model and SPL with perfusion model are considered to investigate the effect of the finite velocity of heat in the skin, perfusion and thickness of the slab on the rate of the thermal wave attenuation. As a reference model, the solution of the classic Fourier heat transfer equation for the considered problems is calculated. A heat flux has direction perpendicular to the surface of skin, considered as a flat slab. Therefore, the equations depend only on time and one spatial variable. Design/methodology/approach First of all the T-functions for the Pennes’ equation and for the SPL model with perfusion are derived. Then, an approximate solutions of the problems are expressed in the form of a linear combination of the T-functions. The T-functions satisfy the equation modeling the problem under consideration. Therefore, approximating a solution of a problem with a linear combination of n T-functions one obtains a function that satisfies the equation. The unknown coefficients of the linear combination are obtained as a result of minimization of the functional that describes an inaccuracy of satisfying the initial and boundary conditions in a mean-square sense. Findings The sets of T-functions for the Pennes’ equation and for the SPL model with perfusion are derived. An infinite set of these functions is a complete set of functions and stands for a base functions layout for the space of solutions for the equation used to generate them. Then, an approximate solutions of the initial-boundary problem have been found and compared to find out the effect of finite velocity of heat in the skin, perfusion and thickness of the slab on the rate of the thermal wave attenuation. Research limitations/implications The methods used in the literature to find an approximate solution of any bioheat transfer problems are more complicated than the one used in the presented paper. However, it should be pointed out that there is some limitation concerning the T-function method, namely, the greater number of T-function is used, the greater condition number becomes. This limitation usually can be overcome using symbolic calculations or conducting calculations with a large number of significant digits. Originality/value The T-functions for the Pennes’ equation and for the SPL equation with perfusion have been reported in this paper for the first time. In the literature, the T-functions are known for other linear partial differential equations (e.g. harmonic functions for Laplace equation), but for the first time they have been derived for the two aforementioned equations. The results are discussed with respect to practical applications.

Thermo-diffusion of solid cylinders based upon refined dual-phase-lag models

2020 ◽  
Vol 16 (6) ◽  
pp. 1417-1434
Author(s):  
Ashraf M. Zenkour
Keyword(s):  
Single Phase ◽  
Chemical Potential ◽  
Thermal Flux ◽  
Closed Form Solution ◽  
Generalized Thermoelasticity ◽  
Phase Lag ◽  
Dual Phase ◽  
Solid Cylinder ◽  
Content Type ◽  
Coupled Equations

PurposeThe thermo-diffusion analysis of an isotropic cylinder under thermal flux and chemical potential impacts has been discussed. Improvements of Green and Naghdi generalized thermoelasticity theory have been proposed.Design/methodology/approachSome models with and without energy dissipation have been presented as well as the simple forms of Green–Naghdi (G–N) theories. These novel multi- and single-/dual-phase-lag models are presented to investigate the thermo-diffusion of the solid cylinder. The closed-form solution of thermo-diffusion governing equations of solid cylinder has been obtained to deduce all field variables.FindingsA comparison study between the simple G–N II and III models and their improved models has been presented. The validations of outcomes are acceptable and so benchmarks are reported to help other investigators in their future comparisons.Originality/valueThe modified Green and Naghdi theories of types II and III are presented to get novel and accurate models of single- and dual-phase-lag of multiterms. The heat of mass diffusion equation as well as the constitutive equations for the stresses and chemical potential of a solid cylinder is added to the present formulation. The system of three differential coupled equations is solved, and all field variables are obtained for the thermal diffusion of the solid cylinder. Some validation examples and applications are presented to compare the simple and modified Green and Naghdi theories of types II and III. Sample plots are illustrated along the radial direction of the solid cylinder. Some results are tabulated to serve as benchmark results for future comparisons with other investigators. The reported and illustrated results show that the simple G–N II and III models yield the largest values of all field quantities. The single-phase-lag models give the smallest values. However, the dual-phase-lag model yields results that are intermediate between those of the simple and single-phase-lag G–N models.

Conference report: innovation, interaction … and a lot of data: first time reflections on Internet Librarian International, UK 2018

2019 ◽  
Vol 36 (2) ◽  
pp. 21-22
Author(s):  
Ray Harper
Keyword(s):  
Best Practice ◽  
New Technologies ◽  
Conference Report ◽  
Library Services ◽  
New Techniques ◽  
Content Type ◽  
Making A Difference ◽  
Analyse Data ◽  
Physical Spaces ◽  
First Time

Purpose The purpose of this paper is to summarise a number of presentations at Day 1 of the Internet Librarian International conference, London, UK (16 October 2018). This was the 20th conference in the series, and the three key themes included were the next-gen library and librarian; understanding users, usage and user experience; and inclusion and inspiration: libraries making a difference. Design/methodology/approach This paper reports from the viewpoint of a first-time attendee of the conference. This summarises the main issues raised by each presentation and draws out the key learning points for practical situations. Findings The conference covered a variety of practical ways in which libraries can use technology to support users and make decisions about services. These include developing interactive physical spaces which include augmented reality; introducing “chat-bots” to support users; using new techniques to analyse data; and piloting new ways to engage users (such as coding clubs). A key theme was how we use and harness data in a way that is ethical, effective and relevant to library services. Originality/value This conference focussed on practical examples of how library and information services across sectors and countries are innovating in a period of huge change. The conference gave delegates numerous useful ideas and examples of best practice and demonstrated the strength of the profession in adapting to new technologies and developments.

Interest rate option hedging portfolios without bank account

2019 ◽  
Vol 37 (1) ◽  
pp. 134-142
Author(s):  
Alberto Bueno-Guerrero
Keyword(s):  
Design Methodology ◽  
Contingent Claim ◽  
Necessary And Sufficient Condition ◽  
Barrier Option ◽  
Bank Account ◽  
Content Type ◽  
Option Hedging ◽  
Hedging Portfolio ◽  
Necessary And Sufficient ◽  
First Time

Purpose This paper aims to study the conditions for the hedging portfolio of any contingent claim on bonds to have no bank account part. Design/methodology/approach Hedging and Malliavin calculus techniques recently developed under a stochastic string framework are applied. Findings A necessary and sufficient condition for the hedging portfolio to have no bank account part is found. This condition is applied to a barrier option, and an example of a contingent claim whose hedging portfolio has a bank account part different from zero is provided. Originality/value To the best of the authors’ knowledge, this is the first time that this issue has been addressed in the literature.

A “Learning from Action” workshop in Japan

2019 ◽  
Vol 40 (2) ◽  
pp. 77-83
Author(s):  
Robert Douglas Hinshelwood ◽  
Luca Mingarelli ◽  
Simona Masnata
Keyword(s):  
Far East ◽  
Opportunity To Learn ◽  
Content Type ◽  
Work Activities ◽  
Defensive Role ◽  
Feedback Data ◽  
Experiential Workshop ◽  
First Time ◽  
Practical Implications

Purpose Many people in severe mentally disturbed states do not use language or other symbolic media well or coherently. Therefore, the non-verbal medium needs to be understood by workers with such people. The “Learning from Action” experiential workshop was developed in order to provide an opportunity to learn about hidden messages in the relationships and roles occurring in activities. In August 2017, a workshop was run for the first time in Japan. The purpose of this paper is to report the experience and dynamics observed by the three consultants, who are here the authors of this paper. Design/methodology/approach After the workshop all the staff and members, including interpreters, were invited to give feedback. Findings Analysis of the feedback data showed certain important dynamics, concerning especially dependence, cultural defences and the defensive role of activity in a multicultural context. Research limitations/implications This is an initial experience to be followed up by later feedback and further workshops. Practical implications Workers awareness of non-verbal communication within the roles of work activities is a training possibility. It faces various resistances including the mental health assumptions of meaninglessness of any communication outside the verbal. Originality/value This is a method of training not widely used even in European countries, and is the first in a country in the far east.

Whirling in between the personal and the impersonal

2019 ◽  
Vol 25 (2) ◽  
pp. 257-284
Author(s):  
Armen E. Petrosyan
Keyword(s):  
Organization Theory ◽  
Conceptual Analysis ◽  
Essential Elements ◽  
Organizational Life ◽  
Critical Perspective ◽  
Content Type ◽  
Organizational Goals ◽  
Last Stage ◽  
First Time ◽  
Current Paradigm

Purpose The paper aims to present a systematic conceptual analysis of the problem of organizational goal and to reduce the insights into it provided by the main conceptions taken in their development from one to another, to break out of the ruling paradigm and outline a new solution. Design/methodology/approach The study has been carried out from the historical and critical perspective. Findings The paper discovers the logic of the evolution the approaches to organizational goals have undergone and portrays it in a matrix form in the heart of which is the “zigzag effect”: each posterior stage returns to the essential elements rejected by those preceding it, and the last stage, being diametrically opposite to the first, is, at that, as well as the latter, akin to the intermediate stages. The opportunities afforded by the current paradigm have been exhausted and it seems to run to an impasse. Instead, the author suggests a new frame of orientation: organizational goals are closely interknit with personal, but not reducible to them and bear fundamentally transpersonal character, while the mechanism of involving the preferences of individuals and groups in goal-setting is based on the self-contained interests of the organization they pertain to. Research limitations/implications The findings, conclusions and generalizations obtained can serve for a necessary ground to researchers getting deeper into the essence of what bonds organizational life and activity. Practical implications The material empowers practitioners to comprehend the difficulties of framing cohesive goal and find efficient ways to overcome them. It is of value also to the teachers seeking to present a more exact and elaborate view of teleological foundations of management and organization theory. Originality/value Both the conceptual analysis of the evolution of the approaches to organizational goals and the author’s exposition of its logic and vision of their nature are provided for the first time.

scholarly journals Mechanical and Thermoelectric Properties of Bulk AlSb Synthesized by Controlled Melting, Pulverizing and Subsequent Vacuum Hot Pressing

2019 ◽  
Vol 9 (8) ◽  
pp. 1609 ◽  
Author(s):  
A. K. M. Ashiquzzaman Shawon ◽  
Soon-Chul Ur
Keyword(s):  
Mechanical Properties ◽  
Intermetallic Compound ◽  
Thermoelectric Properties ◽  
Hot Pressing ◽  
Single Phase ◽  
Aluminum Antimonide ◽  
Simple Method ◽  
Group Iii ◽  
Indirect Band Gap ◽  
First Time

Aluminum antimonide is a semiconductor of the Group III-V order. With a wide indirect band gap, AlSb is one of the least discovered of this family of semiconductors. Bulk synthesis of AlSb has been reported on numerous occasions, but obtaining a single phase has always proven to be extremely difficult. This work reports a simple method for the synthesis of single-phase AlSb. Subsequently, consolidation was done into a near single-phase highly dense semiconductor in a form usable for thermoelectric applications. Further, the thermoelectric properties of this system are accounted for the first time. In addition, the mechanical properties of the intermetallic compound are briefly discussed for a possibility of further use.

The drivers of corporate governance disclosure: the case of Nifty 500 Index

2018 ◽  
Vol 60 (2) ◽  
pp. 681-700 ◽  
Author(s):  
Androniki Katarachia ◽  
Electra Pitoska ◽  
Grigoris Giannarakis ◽  
Elpida Poutoglidou
Keyword(s):  
Corporate Governance ◽  
Financial Leverage ◽  
Policy Makers ◽  
Content Type ◽  
Explanatory Variables ◽  
Size Number ◽  
Governance Practices ◽  
Board Director ◽  
First Time ◽  
Governance Disclosure

Purpose Based on agency theory, the purpose of this paper is to investigate the determinants on the dissemination level of corporate governance disclosure (CGD). Design/methodology/approach The sample of the study incorporates listed companies in Nifty 500 Index for the period 2009-2014. The Governance Disclosure Score calculated by Bloomberg is used as a proxy for the dissemination level of corporate governance information. In total, eight explanatory variables are uses, namely, board’s size, number of board meetings, CEO duality, presence of women on the board, company’s size, financial performance, Tobin’s Q ratio and financial leverage. Findings The results of study suggest a need for improvement in CGDs by Indian companies, as they fail to comply the majority of the proposed disclosure items. Furthermore, it is revealed that the number of board director, the value of company, the financial leverage and the presence of women affect negatively the dissemination level of corporate governance information. While, the size of company is the only determinant that positively affects the extent of CGD. Practical implications The results are valuable because they reveal the attributes that determines which companies needs less or extra monitoring by shareholders and investors regarding the applied corporate governance practices. In addition, the study can be valuable to policy makers responsible for the regulation of company’s accountability in relation to corporate governance practices. Originality/value The study extents previous studies by incorporating for the first time Bloomberg’s rating approach regarding the dissemination level of CGD in Indian context.

Loyalty program in Africa: risk-seeking and risk-averse adventurers

2014 ◽  
Vol 69 (2) ◽  
pp. 137-157 ◽  
Author(s):  
Shogo Mlozi
Keyword(s):  
Consumer Behavior ◽  
Consumer Products ◽  
Loyalty Programs ◽  
Risk Averse ◽  
Loyalty Program ◽  
Content Type ◽  
Risk Seeking ◽  
Proposed Model ◽  
First Time ◽  
The Relationship

Purpose – This article aims to test the relationship between expected attractiveness-satisfaction-loyalty for international adventure tourists visiting Tanzania. The proposed model is based on travel consumer behavior theoretical constructs extracted from the literature. Design/methodology/approach – This article aims to test the relationship between expected attractiveness-satisfaction-loyalty for international adventure tourists visiting Tanzania. The proposed model is based on travel consumer behavior theoretical constructs extracted from the literature. Findings – The findings for overall model differed from the moderating factors of high risk, low risk, first-time visit and repeat visit. Also, the results are interesting when satisfaction is tested as a mediator. Practical implications – Practitioners could consider the fact that repeat visits may change tourists’ perceptions toward destination and may even increase their inclination to take on risks. This may impact innovation of consumer products in tourism. Also, policy makers could benefit on how loyalty programs can be developed to increase performance. Originality/value – The study offers specific strategic recommendations toward different groups of tourists (i.e. first-time, repeat visitors, risk averse, risk seeking) and proposes logic for setting up a loyalty program as a long-term strategy for success.

The carmine dilemma: does the natural colourant preference outweigh nausea?

2018 ◽  
Vol 120 (8) ◽  
pp. 1915-1928
Author(s):  
Judith Müller-Maatsch ◽  
Johannes Jasny ◽  
Katharina Henn ◽  
Claudia Gras ◽  
Reinhold Carle
Keyword(s):  
Design Methodology ◽  
Consumer Perception ◽  
Natural Food ◽  
German Population ◽  
Misleading Information ◽  
Content Type ◽  
Broad Cross Section ◽  
First Time ◽  
Self Administered Questionnaire ◽  
Insight Into

Purpose The purpose of this paper is to provide insight into the consumers’ perception of natural and artificial food colourants. Furthermore, attitudes towards the application of carmine, being technically important and ubiquitously used to impart red shades, are assessed and analysed. Originating from insects, carmine is considered as natural but may arouse disgust. Design/methodology/approach In total, 625 individuals were surveyed using an online, self-administered questionnaire to represent a broad cross-section of the German population. Findings Independent of their origin, the application of colourants was rejected by 57.0 per cent of the interviewees. In total, 31.8 per cent of the participants stated a neutral attitude, while only 11.2 per cent expressed a positive notion. Most respondents preferred colourants from natural sources to artificial ones. While consumers perceive natural food colourants composed of genuine plant pigments positively, 61.6 per cent of respondents disliked the application of animal-derived colourants, 24.8 per cent of them did neither reject nor like it, and only 13.6 per cent of the interviewees stated a positive attitude towards them. The findings of this paper further indicate consumers’ preference for colourants to be either artificial or plant-derived rather than carmine. Food colourants are being rejected, possibly due to misleading information and confusing labelling. Consequently, information about carmine, including its origin and production, did not increase the aversion to products that are dyed with it, but increased their acceptance. Originality/value This study outlines consumer perception and attitudes towards food colourants. For the first time, the findings of this paper report the effect of revealing information about an additive, which initially aroused disgust, and its influence on consumer perception.

A multi-manned assembly line balancing problem with classified teams: a new approach

2016 ◽  
Vol 36 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Hamid Yilmaz ◽  
Mustafa Yilmaz
Keyword(s):  
Design Methodology ◽  
Assembly Line ◽  
Assembly Line Balancing ◽  
Line Balancing ◽  
Test Problems ◽  
New Approach ◽  
Content Type ◽  
Line Test ◽  
Assembly Line Balancing Problem ◽  
First Time

Purpose – Within team-oriented approaches, tasks are assigned to teams before being assigned to workstations as a reality of industry. So it becomes clear, which workers assemble which tasks. Design/methodology/approach – Team numbers of the assembly line can increase with the number of tasks, but at the same time, due to physical situations of the stations, there will be limitations of maximum working team numbers in a station. For this purpose, heuristic assembly line balancing (ALB) procedure is used and mathematical model is developed for the problem. Findings – Well-known assembly line test problems widely used in the literature are solved to indicate the effectiveness and applicability of the proposed approach in practice. Originality/value – This paper draws attention to ALB problem in which workers have been assigned to teams in advance due to the need for specialized skills or equipment on the line for the first time.

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