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Article
Publication date: 1 April 1993

Hamid Z. Fardi

An empirical velocity‐field relationship, based on Monte Carlo simulation, is used to modify a drift‐diffusion model for the characterization of short gate GaAs MESFET's. The…

43

Abstract

An empirical velocity‐field relationship, based on Monte Carlo simulation, is used to modify a drift‐diffusion model for the characterization of short gate GaAs MESFET's. The modified drift‐diffusion model is used to generate both the steady‐state and the small‐signal parameters of submicron GaAs MESFET's. The current, transconductance, and cutoff frequency are compared with two‐dimensional Monte Carlo simulation results on a 0.2 µm gate‐length. The model is also used to predict measured I‐V and s‐parameters of a 0.5 µm gate‐length ion‐implanted GaAs MESFET. The comparison and the analysis made, support the accuracy of the modified drift‐diffusion simulator and makes it computationally efficient for analysis of short‐gate devices.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 12 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 April 1994

Hamid Z. Fardi

Numerical device simulation is developed to study the steady‐state and transient current‐voltage characteristics of double heterostructure AlGaAs/GaAs PNPN electro‐photonic device…

38

Abstract

Numerical device simulation is developed to study the steady‐state and transient current‐voltage characteristics of double heterostructure AlGaAs/GaAs PNPN electro‐photonic device when its performance is influenced by the presence of interface and bulk recombination mechanism. The simulation results show that the holding current and voltage and the breakover point are strongly affected by varying the minority carrier lifetime at outer heterojunctions. Numerical results also indicate that shortening the minority carrier lifetime in the inner PN homojunction region only increases the OFF‐state current. These results are in agreement with experimental data on AlGaAs/GaAs PNPN devices. The numerical modelling approach taken in this study is shown to be essential in the design and optimization of PNPN switch.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 13 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 September 2002

H.Z. Fardi

An energy balance equation model coupled with drift‐diffusion transport equations are solved in heterojunction p‐i‐n diodes with embedded single quantum well to model hot electron…

1099

Abstract

An energy balance equation model coupled with drift‐diffusion transport equations are solved in heterojunction p‐i‐n diodes with embedded single quantum well to model hot electron effects. A detailed formulation of hot electron transport is presented. In the well, the carrier energy levels are estimated from the analytical expressions applied to a quantum well with finite height. Both bound and free carriers are modeled by Fermi‐Dirac statistics. Both size quantization and the two dimensional density of states in the well are considered. Thermionic emission is applied to the heterojunctions and quantum wells boundary. Energy transfer among the charge carriers and crystal lattice is modeled by an energy relaxation lifetime. Two sets of devices are simulated. First, the simulated kinetic energy and carrier density profiles were compared with published Monte Carlo results on an GaAs n+/n/n+ diode. Second, the current‐voltage characteristics of an embedded single quantum well AlGaAs/GaAs p‐i‐n structure was compared with measured data. Both comparisons are satisfactory and demonstrate the usefulness of the model for studying quantum well structures.

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COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 21 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 13 November 2007

Hamid Z. Fardi

To model the differential dc gain, base resistance, and current voltage performance of 4H‐Silicon Carbide (SiC) bipolar junction transistors (BJT) operating at and above room…

479

Abstract

Purpose

To model the differential dc gain, base resistance, and current voltage performance of 4H‐Silicon Carbide (SiC) bipolar junction transistors (BJT) operating at and above room temperature. Accurate modeling will result in improved process efficiency, interpretation of experimental data, and insight into device behavior.

Design/methodology/approach

The PISCES two dimensional device simulation program is used to allow for modeling the behavior of 4H‐SiC BJT. The physical material parameters in PISCES such as carrier's mobility and lifetime, temperature dependent bandgap, and the density of states are modified to accurately represent 4H‐SiC. The simulation results are compared with the measured experimental data obtained by others. The comparisons made with the experimental data are for two different devices that are of interest in power electronics and RF applications.

Findings

The simulation results predict a dc current gain of about 25 for power device and a gain of about 20 for RF device in agreement with the experimental data. The comparisons confirm the accuracy of the modeling employed.

Research limitations/implications

The simulated current‐voltage characteristics indicate that higher gain may be achieved for 4H‐SiC transistors if the leakage current is reduced.

Practical implications

The simulation work discussed in this paper complements the current research in the design and characterization of 4H‐SiC bipolar transistors. The model presented will aid in interpreting experimental data at a wide range of temperatures.

Originality/value

This paper reports on a new model that provides insight into the device behavior and shows the trend in the dc gain performance important for the design and optimization of 4H‐SiC bipolar transistors operating at or above the room temperature.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 9 August 2024

Ahmed Babeker Elhag, Ali Raza, Nabil Ben Kahla and Muhammed Arshad

The external confinement provided by the fiber-reinforced polymer (FRP) sheets leads to an improvement in the axial compressive strength (CS) and strain of reinforced concrete…

47

Abstract

Purpose

The external confinement provided by the fiber-reinforced polymer (FRP) sheets leads to an improvement in the axial compressive strength (CS) and strain of reinforced concrete structural members. Many studies have proposed analytical models to predict the axial CS of concrete structural members, but the predictions for the axial compressive strain still need more investigation because the previous strain models are not accurate enough. Moreover, the previous strain models were proposed using small and noisy databases using simple modeling techniques. Therefore, a rigorous approach is needed to propose a more accurate strain model and compare its predictions with the previous models.

Design/methodology/approach

The present work has endeavored to propose strain models for FRP-confined concrete members using three different techniques: analytical modeling, artificial neural network (ANN) modeling and finite element analysis (FEA) modeling based on a large database consisting of 570 sample points.

Findings

The assessment of the previous models using some statistical parameters revealed that the estimates of the newly recommended models were more accurate than the previous models. The estimates of the new models were validated using the experimental outcomes of compressive members confined with carbon-fiber-reinforced polymer (CFRP) wraps. The nonlinear FEA of the tested samples was performed using ABAQUS, and its estimates were equated with the calculations of the analytical and ANN models. The relative investigation of the estimates solidly substantiates the accuracy and applicability of the recommended analytical, ANN and FEA models for predicting the axial strain of CFRP-confined concrete compression members.

Originality/value

The research introduces innovative methods for understanding FRP confinement in concrete, presenting new models to estimate axial compressive strains. Utilizing a database of 570 experimental samples, the study employs ANNs and regression analysis to develop these models. Existing models for FRP-confined concrete's axial strains are also assessed using this database. Validation involves testing 18 cylindrical specimens confined with CFRP wraps and FE simulations using a concrete-damaged plastic (CDP) model. A comprehensive comparative analysis compares experimental results with estimates from ANNs, analytical and finite element models (FEMs), offering valuable insights and predictive tools for FRP confinement in concrete.

Details

Multidiscipline Modeling in Materials and Structures, vol. 20 no. 5
Type: Research Article
ISSN: 1573-6105

Keywords

Available. Open Access. Open Access
Article
Publication date: 29 September 2022

Sumaira Siddiky, Randi Swandaru and Aishath Muneeza

Micro-enterprises, like any other business entity, face financing challenges. However, micro-enterprises often cannot access financial institutions as they cannot fulfill the…

1412

Abstract

Purpose

Micro-enterprises, like any other business entity, face financing challenges. However, micro-enterprises often cannot access financial institutions as they cannot fulfill the conditions to obtain financing facilities from a formal financial institution. As such, they have to rely on family or friends for financing needs. The most critical challenge faced in this regard to Muslim micro-enterprises is finding out a way in which family and friends could give a financial helping hand without the involvement of riba (interest). At the same time, the person giving the financing can enjoy a profit. This paper aims to propose the Tawarruq Fardi Financing (TFF) model that Islamic micro-enterprises could use to fulfill their financial needs. It becomes a solution when obtaining financing from friends and family or any other third party who could be a private investor who does not want to engage in an equity relationship.

Design/methodology/approach

This study adopts a qualitative research methodology, combining descriptive and content analysis using the inductive reasoning approach.

Findings

The paper's outcome shows that the proposed TFF could assist Islamic micro-enterprises in obtaining Shariah-compliant financing without engaging in an equity partnership. It allows them to fulfill their financing needs bearing in mind the interest of both parties involved in the transaction.

Originality/value

This research will assist Islamic micro-enterprises to find out a Shariah-compliant financing facility from family, friends and any other private investors without entering into an equity relationship. The proposed model would be a Shariah-compliant alternative to interest-free loans and engaging in an equity relationship for the sake of getting benefits for both parties involved in the transaction.

Details

PSU Research Review, vol. 8 no. 2
Type: Research Article
ISSN: 2399-1747

Keywords

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Book part
Publication date: 30 May 2019

Homa Khorasani Esmaeili

Environment Management, Solid Waste Management.

Abstract

Subject Area

Environment Management, Solid Waste Management.

Study Level

This case is suitable to be used in advanced undergraduate and MBA/MSc level.

Case Overview

This case revolves around the challenges pertaining to waste management in Iran. Poor waste management practices can result in soil contamination, water pollution, and air pollution, can cause respiratory problem, and can create permanent adverse health effect. Thus, a solid waste management system is needed for safeguarding the public health, safety, and welfare. However, it seems not an easy task for the developing countries, and Iran is not an exception to this. Recycling has three particular steps: collection and processing, manufacturing, and purchasing new products which made from recycled materials which require heavy investment. Lack of investment in the Iranian recycling sector has made this issue more complicated and lagging behind. This case highlights the challenges faced by the Iranian Municipality in this regard.

Expected Learning Outcomes

The learning objectives are as follows:

  • to expose students to an actual situation where they will be aware of the necessity to care for the environment and reduce and reuse the products that they are utilizing in their every days’ life;

  • to highlight the need of a municipal waste management system to make route optimization for waste collection and transport system, storage, recycling plan, compost and incineration facility, proper site for landfill, etc.; and

  • to emphasize the required support from all stake holders in managing waste.

to expose students to an actual situation where they will be aware of the necessity to care for the environment and reduce and reuse the products that they are utilizing in their every days’ life;

to highlight the need of a municipal waste management system to make route optimization for waste collection and transport system, storage, recycling plan, compost and incineration facility, proper site for landfill, etc.; and

to emphasize the required support from all stake holders in managing waste.

Details

Green Behavior and Corporate Social Responsibility in Asia
Type: Book
ISBN: 978-1-78756-684-2

Keywords

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Article
Publication date: 12 August 2014

Kazi Tanvir Mahmud, M. Kabir Hassan, Md. Ferdous Alam, Kazi Sohag and Farhana Rafiq

The purpose of this paper is to assess the impact of zakat fund on the food expenditure of the households to assess the impact of zakat fund on the agricultural production of the…

1330

Abstract

Purpose

The purpose of this paper is to assess the impact of zakat fund on the food expenditure of the households to assess the impact of zakat fund on the agricultural production of the households and to assess the opinion of the zakat recipients on food security status under zakat program.

Design/methodology/approach

Samples were selected for this study using the simple random sampling (SRS) technique. A total of 149 households were selected from 196 households. A survey was conducted during January to March 2011 among the project beneficiaries using questionnaire. The ordinary least squares technique was used to assess the impact of zakat on food security status of the zakat recipients. Heteroscedasticity problem was detected in this study which was corrected using White's method. Logit model was used to assess the opinions of the zakat recipients on their food security status under the Hasana project.

Findings

This study shows that amount of zakat provided to the poor recipients failed to create any significant influence on their agricultural production, food expenditure and food security status. The study also shows that household income, family members’ involvement in agricultural activities and numbers of income-generating activities pursued by the households were the key determinants of households’ food consumption.

Originality/value

This study helps in assessing the opinion of the zakat recipients about the effectiveness of the zakat program on their living standard in terms of household agricultural production and food security and also assisting in policy planning for alleviating rural poverty in Bangladesh through the zakat system.

Details

International Journal of Islamic and Middle Eastern Finance and Management, vol. 7 no. 3
Type: Research Article
ISSN: 1753-8394

Keywords

Available. Open Access. Open Access
Article
Publication date: 14 October 2021

Sakhri Aicha and Ahcene Merad

This study describes the applicability of the a priori estimate method on a nonlocal nonlinear fractional differential equation for which the weak solution's existence and…

1069

Abstract

Purpose

This study describes the applicability of the a priori estimate method on a nonlocal nonlinear fractional differential equation for which the weak solution's existence and uniqueness are proved. The authors divide the proof into two sections for the linear associated problem; the authors derive the a priori bound and demonstrate the operator range density that is generated. The authors solve the nonlinear problem by introducing an iterative process depending on the preceding results.

Design/methodology/approach

The functional analysis method is the a priori estimate method or energy inequality method.

Findings

The results show the efficiency of a priori estimate method in the case of time-fractional order differential equations with nonlocal conditions. Our results also illustrate the existence and uniqueness of the continuous dependence of solutions on fractional order differential equations with nonlocal conditions.

Research limitations/implications

The authors’ work can be considered a contribution to the development of the functional analysis method that is used to prove well-positioned problems with fractional order.

Originality/value

The authors confirm that this work is original and has not been published elsewhere, nor is it currently under consideration for publication elsewhere.

Details

Arab Journal of Mathematical Sciences, vol. 29 no. 2
Type: Research Article
ISSN: 1319-5166

Keywords

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Article
Publication date: 4 August 2020

Leyla Bouzid, Mohand Hamizi, Naceur-Eddine Hannachi, Aghiles Nekmouche and Karim Akkouche

The purpose of this study is to establish a relationship between causes and effects, the respect of materials characteristics values [concrete compressive strength (fc) and steel…

102

Abstract

Purpose

The purpose of this study is to establish a relationship between causes and effects, the respect of materials characteristics values [concrete compressive strength (fc) and steel yield stress (fy)] and the norms of the construction dispositions value (covers). This study is motivated by the post-seismic damages related to the plastification of the reinforced concrete (RC)/beams sections, named plastic hinges. The results are given by fragility curves representing the failure probability (Pf) of the plastic hinges versus covers value.

Design/methodology/approach

A mechanical-reliability coupling methodology is proposed and performed on three frames (three, six and nine storey). For each frame, seven covers the value of reinforcement steel bars has been taken into account in the beams. After definition of the limit state function G(x), a process of idea to twin-track; deterministic and probabilistic, is considered. Thus, numerical simulations are carried out under ETABS© software, to extract a soliciting moments Ms(x). Then, ultimate moments Mu(x), the result of reliability approach are calculated using Monte Carlo Simulations. In this step, two random variables; concrete compressive strength in 28 days of age (fc) and steel yield stress (fy), have been studied.

Findings

In the mechanical study, the results show that, the first plastic hinge appears at the beams for all frames. In the reliability study, the (fy) variation shows that all plastic hinges are in failure domain, nevertheless, the (fc) variation leads to have all sections in the safety domain, except A7 and B7 models. The failure probability (Pf) calculation according to (fc) and (fy) shows that an absolute error of 0.5 cm in the steel bars covers can switch the frame from the safety domain to the failure domain.

Originality/value

The plastic hinges reliability of the RC/ frame structures is independent on the high of the structure. The (fc) random variable according to the used distribution law does not affect the reliability (safety or failure). However, the impact of the steel yield stress variation (fy) is not negligible. The errors in covers affect considerably the strength of the elements.

Details

World Journal of Engineering, vol. 17 no. 5
Type: Research Article
ISSN: 1708-5284

Keywords

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