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Article
Publication date: 3 August 2020

Emad Ebrahimi

Multiphase and quadrature voltage-controlled oscillators (QVCOs) play key roles in modern communication systems and their phase noise performance affects the performance of the…

271

Abstract

Purpose

Multiphase and quadrature voltage-controlled oscillators (QVCOs) play key roles in modern communication systems and their phase noise performance affects the performance of the overall system. Different studies are devoted to efficient quadrature signals generation. This paper aims to present a new low-phase noise superharmonic injection-locked QVCO.

Design/methodology/approach

The proposed QVCO is comprised of two identical inductor-capacitor circuit (LC)-voltage-controlled oscillators (VCOs) in which second harmonics, with 180° phase shift, are injected from one core VCO to the gate of tail current source of the other VCO via a coupling capacitor. Using second harmonics with high amplitude will switch the tail from the inversion to the accumulation, and therefore, flicker noise is reduced. Also, because of the use of lossless and noiseless coupling elements, that is, coupling capacitors, and also because of the existence of an inherent high-pass filter, the proposed LC-QVCO has a good phase noise performance.

Findings

The introduced technique is designed and simulated in a commercial 0.18 µm radio frequency complementary metal oxide semiconductor (RF-CMOS) technology and 10 dB improvement of close-in phase noise is achieved (compared to the conventional method). Simulation results show that the phase noise of the proposed QVCO is −130.3 dBc/Hz at 3 MHz offset from 5.76 GHz center frequency, while the total direct current (DC) current drawn from a 0.9-V power supply is 4.25 mA (figure of merit = −190.2 dBc). Monte Carlo simulation results show that the figure of merit of the circuit has a Gaussian distribution with mean value and standard deviation of −189.97 dBc and 0.183, respectively.

Originality/value

This technique provides a new simple but efficient superharmonic coupling and noise shaping method that reduces close-in phase noise of superharmonic multiphase VCOs by switching of tail transistors with 2 ω0 (second harmonic of oscillation frequency). No extra devices such as area-consuming transformer or additional power-hungry oscillator are used for coupling.

Details

Circuit World, vol. 47 no. 4
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 29 March 2022

Emad Kazemzadeh, Mohammad Taher Ahmadi Shadmehri, Taghi Ebrahimi Salari, Narges Salehnia and Alireza Pooya

The purpose of this study is to examine oil price shocks on US shale oil supply and energy security during the period 2000q1–2020q4.

195

Abstract

Purpose

The purpose of this study is to examine oil price shocks on US shale oil supply and energy security during the period 2000q1–2020q4.

Design/methodology/approach

In this study, the Shannon–Wiener index was used to calculate energy security, and then a structural vector autoregression (VAR) was applied to measure the effect of oil price shocks.

Findings

The results of the variance decomposition indicate that oil prices account for about 20% of changes in US shale oil production, while it explains only about 3% of changes in energy security. Finally, historical decomposition confirms the results of impulse response functions.

Originality/value

The novelty of this study is that so far, no study has examined the effect of oil price shock on shale oil production and energy security in the USA using the structural VAR model. This study also used the latest Shannon–Wiener index as a measure of energy security in the USA. The reason for selecting this index is that, in addition to considering the share of the total consumption of each primary energy, the share of energy imports from each country as well as the political risk of energy exporting countries to the USA are also included.

Details

International Journal of Development Issues, vol. 21 no. 2
Type: Research Article
ISSN: 1446-8956

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Article
Publication date: 10 May 2022

Emad Kazemzadeh, Mohammad Taher Ahmadi Shadmehri, Taghi Ebrahimi Salari, Narges Salehnia and Alireza Pooya

The USA is one of the largest oil producers in the world. For this purpose, the authors model and predict the US conventional and unconventional oil production during the period…

230

Abstract

Purpose

The USA is one of the largest oil producers in the world. For this purpose, the authors model and predict the US conventional and unconventional oil production during the period 2000–2030.

Design/methodology/approach

In this research, the system dynamics (SD) model has been used. In this model, economic, technical, geopolitical, learning-by-doing and environmental (social costs of carbon) issues are considered.

Findings

The results of the simulation, after successfully passing the validation test, show that the US unconventional oil production rate under the optimistic scenario (high oil prices) in 2030 is about 12.62 million barrels/day (mb/day), under the medium oil price scenario is about 11.4 mb/day and under the pessimistic scenario (low oil price) is about 10.18 mb/day. The results of US conventional oil production forecasting under these three scenarios (high, medium and low oil prices) show oil production of 4.62, 4.26 and 3.91 mb/day, respectively.

Originality/value

The contribution of this study is important in several respects: First, by modeling SD that technical, economic, proven reserves and technology factors are considered, this paper models US conventional and unconventional oil production separately. In this modeling, nonlinear relationships and feedback loops are presented to better understand the relationships between variables. Second, given the importance of environmental issues, the modeling of social costs of CO2 emissions per barrel of oil is also presented and considered as a part of oil production costs. Third, conventional and unconventional US oil production by 2030 is forecast separately, the results of this study could help policymakers to develop unconventional oil and plan for energy self-sufficiency.

Details

International Journal of Energy Sector Management, vol. 17 no. 2
Type: Research Article
ISSN: 1750-6220

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Article
Publication date: 11 August 2022

Emad Kazemzadeh, Mohammad Taher Ahmadi Shadmehri, Taghi Ebrahimi Salari, Narges Salehnia and Alireza Pooya

One of the most important ways to pay attention to sustainable economic development is to invest in green technology and alter the energy consumption structure (ECS) in countries…

126

Abstract

Purpose

One of the most important ways to pay attention to sustainable economic development is to invest in green technology and alter the energy consumption structure (ECS) in countries. Changing the ECS can be important in two ways: first, it increases the diversity of energy consumption and reduces energy dependence on other countries. Second, the use of highly polluted nonrenewable energy sources (such as oil and coal) is reduced, leading to the transfer of energy to natural gas with less carbon emissions or renewable energy. To this end, the authors examined the asymmetric effects of eco-innovation on the US ECS from 1980 to 2019. This paper aims to address this issue.

Design/methodology/approach

In this research, the nonlinear autoregressive distributed lag (ARDL) (NARDL) model is used and the results are compared with the linear ARDL model.

Findings

The ARDL results also confirm the positive effects of oil prices and GDP per capita in the long run. On the other hand, short-term and long-term Wald test results confirm the nonlinear effects of eco-innovation (LPATENT) on US ECS. These results indicate that 1% positive shock in LPATENTˆ+ increases the ECS by 0.179, while 1% negative fluctuations (LPATENTˆ-) leads to a decrease (−0.085) in the ECS. However, the ARDL results, in general, show the positive effects of LPATENT on the ECS in long run. Evidence suggests that ignoring nonlinear effects can lead to inaccurate results. Policy suggestions for environmental technology innovation are presented in the results.

Originality/value

This research has innovations in various aspects so that the previous studies in this field have examined the effects of environmental innovation on renewable or nonrenewable energy consumption, and so far no study has been done on the ECS. In this research, the Shannon–Wiener index has been used to calculate the ECS.

Details

Management of Environmental Quality: An International Journal, vol. 34 no. 1
Type: Research Article
ISSN: 1477-7835

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Article
Publication date: 27 March 2007

Mobin Salasi, Taghi Shahrabi and Emad Roayaei

To study and compare the inhibition effects of eco‐friendly inhibitors of sodium silicate and 1‐hydroxyethylidene 1,1 diphosphonic acid (HEDP) in corrosion control and prevention…

744

Abstract

Purpose

To study and compare the inhibition effects of eco‐friendly inhibitors of sodium silicate and 1‐hydroxyethylidene 1,1 diphosphonic acid (HEDP) in corrosion control and prevention of soft water discolouration (red water) in carbon steel pipelines.

Design/methodology/approach

Electrochemical impedance and Tafel polarization measurements were used to study corrosion inhibition properties. The experiments were carried out under different concentration ratios of inhibitors. Different hydrodynamic conditions were applied to simulate pipeline fluid flow. Scanning electron microscopy (SEM) and EDAX analysis were used for surface studies.

Findings

It was observed that corrosion inhibitor combinations under static conditions showed synergistic effects at low concentrations. The inhibition efficiency and synergistic behaviours of inhibitors were enhanced as the electrolyte turbulence was increased. In addition, the inhibitor concentration value required to reach maximum inhibition decreased. It was found that at 20 ppm sodium silicate and 5 ppm HEDP, co‐inhibition efficiencies increased significantly to more than 90 per cent and the corrosion rate decreased far below 1 mpy as the electrode rotational speed was increased. Surface studies using SEM revealed the formation of a compact and uniform film of co‐inhibitors.

Practical implications

The results of this paper can be used for the development of effective, non‐toxic and economically attractive corrosion inhibitor formulations for soft water transmission pipelines.

Originality/value

The observed synergistic behaviour can be due to the incorporation of the silicate gel‐like network through organic phosphorous bonds. The hydrodynamic condition of the electrolyte leads to enhancement of inhibition efficiency, which indicates that the corrosion inhibition was mass transfer controlled.

Details

Anti-Corrosion Methods and Materials, vol. 54 no. 2
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 28 June 2024

Bahareh Osanlou and Emad Rezaei

This study aims to examine the effect of Muslim consumers’ religiosity on their brand verdict regarding clothing brands, through the mediating role of decision-making style, brand…

318

Abstract

Purpose

This study aims to examine the effect of Muslim consumers’ religiosity on their brand verdict regarding clothing brands, through the mediating role of decision-making style, brand status and brand attitude.

Design/methodology/approach

Structural equation modeling was used to analyze the data collected from 200 clothing buyers in Mashhad, one of Iran’s religious cities.

Findings

The results indicate that intrapersonal religiosity, compared to interpersonal religiosity, has a more significant effect on Muslim consumers’ decision-making styles, and different decision-making styles of Muslim consumers affect their brand verdict through brand status and brand attitude.

Research limitations/implications

The research sample consists solely of respondents from the Islamic religion. Therefore, the impact of religiosity might differ among individuals from other religions, such as Christianity and Judaism.

Practical implications

This study’s findings are crucial for clothing brands, both national and international, that cater to the Muslim customers’ market. They need to consider the degree of religiosity when segmenting and targeting their market. This study shows that clothing brand marketers can best influence the brand verdict of Muslim consumers by targeting those with a brand-loyal decision-making style, focusing on their religious beliefs.

Originality/value

To achieve success in Iran’s Muslim market, marketers must consider their consumers’ religious beliefs and tailor their marketing plans accordingly. This study aims to investigate the impact of religiosity on consumer behavior toward brands in Iran’s Muslim market.

Details

Journal of Islamic Marketing, vol. 16 no. 1
Type: Research Article
ISSN: 1759-0833

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Article
Publication date: 4 October 2018

Alireza Rahimi, Abbas Kasaeipoor, Emad Hasani Malekshah and Lioua Kolsi

This paper aims to perform the lattice Boltzmann simulation of natural convection heat transfer in cavities included with active hot and cold walls at the side walls and internal…

126

Abstract

Purpose

This paper aims to perform the lattice Boltzmann simulation of natural convection heat transfer in cavities included with active hot and cold walls at the side walls and internal hot and cold obstacles.

Design/methodology/approach

The cavity is filled with double wall carbon nanotubes (DWCNTs)-water nanofluid. Different approaches such as local and total entropy generation, local and average Nusselt number and heatline visualization are used to analyze the natural convection heat transfer. The cavity is filled with DWCNTs-water nanofluid and the thermal conductivity and dynamic viscosity are measured experimentally at different solid volume fractions of 0.01 per cent, 0.02 per cent, 0.05 per cent, 0.1 per cent, 0.2 per cent and 0.5 per cent and at a temperature range of 300 to 340 (K).

Findings

Two sets of correlations for these parameters based on temperature and solid volume fraction are developed and used in the numerical simulations. The influences of different governing parameters such as Rayleigh number, solid volume fraction and different arrangements of active walls on the fluid flow, heat transfer and entropy generation are presented, comprehensively. It is found that the different arrangements of active walls have pronounced influence on the flow structure and heat transfer performance. Furthermore, the Nusselt number has direct relationship with Rayleigh number and solid volume fraction. On the other hand, the total entropy generation has direct and reverse relationship with Rayleigh number and solid volume fraction, respectively.

Originality/value

The originality of this work is to analyze the two-dimensional natural convection using lattice Boltzmann method and different approaches such as entropy generation and heatline visualization.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 10
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 16 May 2016

Lana Bataineh and Emad Abu-Shanab

This study aims to predict the intention to participate (ITP) in public activities by utilizing five levels of e-participation reported in the literature. The study used the…

1546

Abstract

Purpose

This study aims to predict the intention to participate (ITP) in public activities by utilizing five levels of e-participation reported in the literature. The study used the levels of e-informing, e-consulting, e-involving, e-collaborating and e-empowering as predictors of the intention to participate in e-government services.

Design/methodology/approach

An empirical test was adopted using a survey to measure the five levels of e-participation and the dependent variable, ITP in e-government initiatives. The survey included items from previous studies translated to Arabic. Subjects responded to a five-point Likert scale to measure their perceptions regarding the sub-dimensions of each e-participation level. Statistical analyses of the collected data were conducted to test the assumed hypotheses. Multiple regression of the five predictor levels was conducted to predict the ITP in e-government services.

Findings

All the estimated means of e-participation levels were moderately perceived. The regression results indicated a significant prediction of three levels: e-informing, e-consulting and e-empowering. The other two levels (e-involving and e-collaborating) failed to predict the ITP. The coefficient of determination R2 resulting from the regression test was significant at the 0.001 level, which explained 61.9 per cent of the variance in the dependent variable.

Research limitations/implications

The instrument used is a newly developed one in Arabic language, which might have influenced the results. The distinction between e-involving and e-collaborating might not have been recognized by subjects, which might have increased the limitations of the study. The results of this study call for more research to validate the instrument and try to see if new statements of e-consulting and e-involving might be employed. The other side could be to reduce the levels to three levels only or merge the insignificant ones into one (four levels only).

Practical implications

Governments need to assert the role of citizens in the decision-making process. Such assertion is done through the e-participation process.

Social implications

Jordanians perceive the e-informing and e-consulting levels to be a foundation that can be easily attained, but jumping to the e-empowering level means that the society is keen on the partnership with the government.

Originality/value

This study is the first to use the participation levels (five levels) as predictors of the ITP. Most studies have utilized theories such as technology acceptance model (TAM), theory of reseaoned action (TRA) and unified theory of acceptance and use of technology (UTAUT) and other technology adoption theories. Also, this research has established ground for an Arabic survey to measure such levels, regardless of their prediction or description purpose.

Details

Transforming Government: People, Process and Policy, vol. 10 no. 2
Type: Research Article
ISSN: 1750-6166

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Article
Publication date: 2 November 2018

Alireza Rahimi, Abbas Kasaeipoor, Emad Hasani Malekshah, Mohammad Mehdi Rashidi and Abimanyu Purusothaman

This study aims to investigate the three-dimensional natural convection and entropy generation in a cuboid enclosure filled with CuO-water nanofluid.

247

Abstract

Purpose

This study aims to investigate the three-dimensional natural convection and entropy generation in a cuboid enclosure filled with CuO-water nanofluid.

Design/methodology/approach

The lattice Boltzmann method is used to solve the problem numerically. Two different multiple relaxation time (MRT) models are used to solve the problem. The D3Q7–MRT model is used to solve the temperature field, and the D3Q19 is used to solve the fluid flow of natural convection within the enclosure.

Findings

The influences of different Rayleigh numbers (103 < Ra < 106) and solid volume fractions (0 < f < 0.04) on the fluid flow, heat transfer, total entropy generation, local heat transfer irreversibility and local fluid friction irreversibility are presented comprehensively. To predict thermo–physical properties, dynamic viscosity and thermal conductivity, of CuO–water nanofluid, the Koo–Kleinstreuer–Li (KKL) model is applied to consider the effect of Brownian motion on nanofluid properties.

Originality/value

The originality of this work is to analyze the three-dimensional natural convection and entropy generation using a new numerical approach of dual-MRT-based lattice Boltzmann method.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 18 December 2020

Biju Augustine Puthanveettil, Shilpa Vijayan, Anil Raj and Sajan MP

This paper explores and interprets the linkage between total quality management (TQM) practices and organizational performance measures for improving the healthcare firms’…

1107

Abstract

Purpose

This paper explores and interprets the linkage between total quality management (TQM) practices and organizational performance measures for improving the healthcare firms’ performance. Indian healthcare firms are aware of TQM practices and their benefits, but the awareness level varies among the firms and staff. The study looks into the effectiveness of quality awareness to meet quality performance in Indian hospitals.

Design/methodology/approach

A questionnaire based on previous research was circulated among the managers and medical staff. The model linking TQM and organizational performance is analyzed with structural equation modelling and confirmed the hypotheses stated. Interpretations to improve hospital performance are made.

Findings

The study identified ten relevant TQM factors and confirmed their importance towards the improved organizational performance of Indian hospitals. Top management initiative, continuous process improvement and team work are the most contributing TQM factors. Differences in the awareness levels by the management staff and medical staff are attributed. The managers and medical staff are aware of the benefits of TQM towards firm performance, but it is to be improved further.

Research limitations/implications

Cross-validation and interpretation are affected due to the limited sample size. Longitudinal study is recommended to explore the individual hospital as specific cases. Larger sample size is suggested as an extended work to overcome the demographic and infrastructural limitations of the firms included.

Practical implications

The management is more interested in TQM, but there is lack of awareness among the staff. The quality awareness and customer focus by medical staff are the most weakly loaded factors, and the weaknesses can be remedied by the lead role by the hospital management in providing proper training and thereby improving the attitude of the medical staff.

Social implications

Effectiveness of hospital operations is highly dependent on customer focus. Properly communicated, committed and trained staff with good-quality awareness can better implement TQM and thereby improve hospital performance. Lead role by the management is very important, and the paper lists ways to attain these outcomes.

Originality/value

Very little is reported from the Indian healthcare sector linking TQM and outcome performance. The quality awareness, customer focus, communication and learning by the medical staff are to be improved, and the paper suggests ways to link TQM more effectively to improve the performance in hospitals. These findings may be useful to the managers, medical staff and researchers in healthcare to bring better results.

Details

The TQM Journal, vol. 33 no. 6
Type: Research Article
ISSN: 1754-2731

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