S.A. Fam, O.F. Moustafa, T.M. Ezzat and A.M. Motawie
A dewaxed and dearomatized petroleum fraction having a boiling range 180–250°C was oxidised by air at 140°C. under atmospheric pressure using cobalt or manganese naphthenate as…
Abstract
A dewaxed and dearomatized petroleum fraction having a boiling range 180–250°C was oxidised by air at 140°C. under atmospheric pressure using cobalt or manganese naphthenate as catalyst. The oxynaphthenic acids were isolated from the oxidation product, purified and then neutralised to sodium salts.
Tor Guimaraes and Ketan Paranjape
This study aims to test the moderating impact of competition intensity on the relationships between the new product development (NPD) success factors and company success in NPD.
Abstract
Purpose
This study aims to test the moderating impact of competition intensity on the relationships between the new product development (NPD) success factors and company success in NPD.
Design/methodology/approach
A mailed questionnaire collected information from 311 manufacturing companies to test the proposed model with moderated multivariate regression analysis.
Findings
The results corroborate the impact of competition intensity on the relationships between the success factors individually and company success performing NPD.
Research limitations/implications
Despite the relatively broad scope of the proposed model, other success factors and/or moderating and mediating variables may also be important. As such, these variables should be identified and tested in future studies.
Practical implications
In practice, competition is viewed as an unavoidable factor beyond the control of managers within a company. Undeniably, competition is a great stimulant for business innovation. Thus, it is important for managers to understand the need, to focus attention managing the success factors most important to increase the likelihood of long-term success for NPD projects, particularly in markets under intense competition.
Originality/value
While the study is grounded on well-established literature, its major constructs originated from relatively isolated areas of knowledge. The major contribution is empirically testing an integrated model for variables considered important for success in NPD and the moderating effect of intense competition.
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The literature prescribing important determinants of innovation success is grouped into four main areas encompassing strategic leadership, competitive intelligence, management of…
Abstract
Purpose
The literature prescribing important determinants of innovation success is grouped into four main areas encompassing strategic leadership, competitive intelligence, management of technology, and specific characteristics of the company's innovation process. Further, industry clockspeed has been considered to be a possible moderator for these determinants of innovation success. While these major areas of study may indeed be important to enhance company innovation and competitiveness, the existing literature on each area is not being shared by researchers in the other areas. That has led until now to the study of models relatively narrow in scope and primarily focused on the particular research area. This study aims to test these constructs as a set of determinants of innovation success and the possible moderating effect of industry clockspeed.
Design/methodology/approach
A field test using a mailed questionnaire to collect a relatively large sample has been used to test the proposed model. To eliminate possible multicollinearity among the independent variables, a multivariate regression analysis was used.
Findings
The results provide clear evidence about the importance of industry clockspeed as a moderator of the relationships between strategic leadership, competitive intelligence, management of technology, and specific characteristics of the company's innovation process with company success in business innovation. Also, the company's change process as defined here is equally important to low and high clockspeed industries for successfully implementing business innovations.
Research limitation/implications
Despite the relatively broad scope of the proposed model, other factors may also be important and should be included in future studies.
Practical implications
The items used for measuring the main constructs provide further and more specific insights into how managers should go about developing these areas within their organizations.
Originality/value
While the study is grounded in the literature of what until now have been four separate areas of knowledge, it proposed an integrated model for these areas important to business innovation, and empirically tested the model.
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Jitesh Tripathi, Shrikant Warbhe, K.C. Deshmukh and Jyoti Verma
The present work is concerned with the solution of a fractional-order thermoelastic problem of a two-dimensional infinite half space under axisymmetric distributions in which…
Abstract
Purpose
The present work is concerned with the solution of a fractional-order thermoelastic problem of a two-dimensional infinite half space under axisymmetric distributions in which lower surface is traction free and subjected to a periodically varying heat source. The thermoelastic displacement, stresses and temperature are determined within the context of fractional-order thermoelastic theory. To observe the variations of displacement, temperature and stress inside the half space, the authors compute the numerical values of the field variables for copper material by utilizing Gaver-Stehfast algorithm for numerical inversion of Laplace transform. The effects of fractional-order parameter on the variations of field variables inside the medium are analyzed graphically. The paper aims to discuss these issues.
Design/methodology/approach
Integral transform technique and Gaver-Stehfast algorithm are applied to prepare the mathematical model by considering the periodically varying heat source in cylindrical co-ordinates.
Findings
This paper studies a problem on thermoelastic interactions in an isotropic and homogeneous elastic medium under fractional-order theory of thermoelasticity proposed by Sherief (Ezzat and El-Karamany, 2011b). The analytic solutions are found in Laplace transform domain. Gaver-Stehfast algorithm (Ezzat and El-Karamany, 2011d; Ezzat, 2012; Ezzat, El Karamany, Ezzat, 2012) is used for numerical inversion of the Laplace transform. All the integrals were evaluated using Romberg’s integration technique (El-Karamany et al., 2011) with variable step size. A mathematical model is prepared for copper material and the results are presented graphically with the discussion on the effects of fractional-order parameter.
Research limitations/implications
Constructed purely on theoretical mathematical model by considering different parameters and the functions.
Practical implications
The system of equations in this paper may prove to be useful in studying the thermal characteristics of various bodies in real-life engineering problems by considering the time fractional derivative in the field equations.
Originality/value
In this problem, the authors have used the time fractional-order theory of thermoelasticity to solve the problem for a half space with a periodically varying heat source to control the speed of wave propagation in terms of heat and elastic waves for different conductivity like weak conductivity, moderate conductivity and super conductivity which is a new and novel contribution.
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Magdy A. Ezzat, Shereen M. Ezzat and Modhi Y. Alkharraz
The purpose of this study is to develop a comprehensive size-dependent piezoelectric thermo-viscoelastic coupling model that accounts for two fundamentally distinct size-dependent…
Abstract
Purpose
The purpose of this study is to develop a comprehensive size-dependent piezoelectric thermo-viscoelastic coupling model that accounts for two fundamentally distinct size-dependent models that govern fractional dual-phase lag heat transfer and viscoelastic deformation, respectively.
Design/methodology/approach
The fractional calculus has recently been shown to capture precisely the experimental effects of viscoelastic materials. The governing equations are combined into a unified system, from which certain theorems results on linear coupled and generalized theories of thermo-viscoelasticity may be easily established. Laplace transforms and state–space approach will be used to determine the generic solution when any set of boundary conditions exists. The derived formulation is used to two concrete different problems for a piezoelectric rod. The numerical technique for inverting the transfer functions is used to generate observable numerical results.
Findings
Some analogies of impacts of nonlocal thermal conduction, nonlocal elasticity and DPL parameters as well as fractional order on thermal spreads and thermo-viscoelastic response are illustrated in the figures.
Originality/value
The results in all figures indicate that the nonlocal thermal and viscoelastic parameters have a considerable influence on all field values. This discovery might help with the design and analysis of thermal-mechanical aspects of nanoscale devices.
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In the present paper, the new concept of “memory dependent derivative” in the Pennes’ bioheat transfer and heat-induced mechanical response in human living tissue with variable…
Abstract
Purpose
In the present paper, the new concept of “memory dependent derivative” in the Pennes’ bioheat transfer and heat-induced mechanical response in human living tissue with variable thermal conductivity and rheological properties of the volume is considered.
Design/methodology/approach
A problem of cancerous layered with arbitrary thickness is considered and solved analytically by Kirchhoff and Laplace transformation. The analytical expressions for temperature, displacement and stress are obtained in the Laplace transform domain. The inversion technique for Laplace transforms is carried out using a numerical technique based on Fourier series expansions.
Findings
Comparisons are made with the results anticipated through the coupled and generalized theories. The influence of variable thermal, volume materials properties and time-delay parameters for all the regarded fields for different forms of kernel functions is examined.
Originality/value
The results indicate that the thermal conductivity and volume relaxation parameters and MDD parameter play a major role in all considered distributions. This dissertation is an attempt to provide a theoretical thermo-viscoelastic structure to help researchers understand the complex thermo-mechanical processes present in thermal therapies.
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Magdy A. Ezzat and Roland W. Lewis
The system of equations for fractional thermo-viscoelasticity is used to investigate two-dimensional bioheat transfer and heat-induced mechanical response in human skin tissue…
Abstract
Purpose
The system of equations for fractional thermo-viscoelasticity is used to investigate two-dimensional bioheat transfer and heat-induced mechanical response in human skin tissue with rheological properties.
Design/methodology/approach
Laplace and Fourier’s transformations are used. The resulting formulation is applied to human skin tissue subjected to regional hyperthermia therapy for cancer treatment. The inversion process for Fourier and Laplace transforms is carried out using a numerical method based on Fourier series expansions.
Findings
Comparisons are made with the results anticipated through the coupled and generalized theories. The influences of volume materials properties and fractional order parameters for all the regarded fields are examined. The results indicate that volume relaxation parameters, as well as fractional order parameters, play a major role in all considered distributions.
Originality/value
Bio-thermo-mechanics includes bioheat transfer, biomechanics, burn injury and physiology. In clinical applications, knowledge of bio-thermo-mechanics in living tissues is very important. One can infer from the numerical results that, with a finite distance, the thermo-mechanical waves spread to skin tissue, removing the unrealistic predictions of the Pennes’ model.
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Mohamed M. Hendy and Magdy A. Ezzat
Whereas, the classical Green-Naghdi Type II (GN-II) model struggles to accurately represent the thermo-mechanical behavior of thermoelectric MHD due to its inability to account…
Abstract
Purpose
Whereas, the classical Green-Naghdi Type II (GN-II) model struggles to accurately represent the thermo-mechanical behavior of thermoelectric MHD due to its inability to account for the memory effect. A new mathematical model of the GN-II theory incorporates a fractional order of heat transport to address this issue.
Design/methodology/approach
The employment of the matrix exponential method, which forms the basis of the state-space approach in contemporary theory, is central to this strategy. The resulting formulation, together with the Laplace transform techniques, is applied to a variety of problems. Solutions to a thermal shock problem and to a problem of a layer media both without heat sources are obtained. Also, a problem with the distribution of heat sources is considered. The numerical technique is used to achieve the Laplace transform inversion.
Findings
According to the numerical results and its graphs, the influences of the fractional order parameters, figure-of-merit factor, thermoelectric power and Peltier coefficient on the behavior of the field quantities are investigated in the new theory.
Originality/value
The new modeling of thermoelectric MHD has advanced significantly as a result of this work, providing a more thorough and precise tool for forecasting the behavior of these materials under a range of thermal and magnetic conditions.
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Gaurav Mittal and Vinayak Kulkarni
The purpose of this paper is to frame a dual-phase-lag model using the fractional theory of thermoelasticity with relaxation time. The generalized Fourier law of heat conduction…
Abstract
Purpose
The purpose of this paper is to frame a dual-phase-lag model using the fractional theory of thermoelasticity with relaxation time. The generalized Fourier law of heat conduction based upon Tzou model that includes temperature gradient, the thermal displacement and two different translations of heat flux vector and temperature gradient has been used to formulate the heat conduction model. The microstructural interactions and corresponding thermal changes have been studied due to the involvement of relaxation time and delay time translations. This results in achieving the finite speed of thermal wave. Classical coupled and generalized thermoelasticity theories are recovered by considering the various special cases for different order of fractional derivatives and two different translations under consideration.
Design/methodology/approach
The work presented in this manuscript proposes a dual-phase-lag mathematical model of a thick circular plate in a finite cylindrical domain subjected to axis-symmetric heat flux. The model has been designed in the context of fractional thermoelasticity by considering two successive terms in Taylor’s series expansion of fractional Fourier law of heat conduction in the two different translations of heat flux vector and temperature gradient. The analytical results have been obtained in Laplace transform domain by transforming the original problem into eigenvalue problem using Hankel and Laplace transforms. The numerical inversions of Laplace transforms have been achieved using the Gaver−Stehfast algorithm, and convergence criterion has been discussed. For illustrative purpose, the dual-phase-lag model proposed in this manuscript has been applied to a periodically varying heat source. The numerical results have been depicted graphically and compared with classical, fractional and generalized thermoelasticity for various fractional orders under consideration.
Findings
The microstructural interactions and corresponding thermal changes have been studied due to the involvement of relaxation time and delay time translations. This results in achieving the finite speed of thermal wave. Classical coupled and generalized thermoelasticity theories are recovered by considering the various special cases for different order of fractional derivatives and two different translations under consideration. This model has been applied to study the thermal effects in a thick circular plate subjected to a periodically varying heat source.
Practical implications
A dual-phase-lag model can effectively be incorporated to study the transient heat conduction problems for an exponentially decaying pulse boundary heat flux and/or for a short-pulse boundary heat flux in long solid tubes and cylinders. This model is also applicable to study the various effects of the thermal lag ratio and the shift time. These dual-phase-lag models are also practically applicable in the problems of modeling of nanoscale heat transport problems of semiconductor devices and accordingly semiconductors can be classified as per their ability of heat conduction.
Originality/value
To the authors’ knowledge, no one has discussed fractional thermoelastic dual-phase-lag problem associated with relaxation time in a finite cylindrical domain for a thick circular plate subjected to an axis-symmetric heat source. This is the latest and novel contribution to the field of thermal mechanics.
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The purpose of this paper is to deal with a new generalized model of thermoelasticity theory with memory-dependent derivatives (MDD).
Abstract
Purpose
The purpose of this paper is to deal with a new generalized model of thermoelasticity theory with memory-dependent derivatives (MDD).
Design/methodology/approach
The two-dimensional equations of generalized thermoelasticity with MDD are solved using a state-space approach. The numerical inversion method is employed for the inversion of Laplace and Fourier transforms.
Findings
The solutions are presented graphically for different values of time delay and kernel function.
Originality/value
The governing coupled equations of the new generalized thermoelasticity with time delay and kernel function, which can be chosen freely according to the necessity of applications, are applied to a two-dimensional problem of an isotropic plate.