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Article
Publication date: 2 February 2021

D. Srikar and Sundru Anuradha

This study aims to propose a two-element multi-input-multi-output (MIMO) antenna for cognitive radio MIMO applications to avoid the complexities involved in reconfigurable…

304

Abstract

Purpose

This study aims to propose a two-element multi-input-multi-output (MIMO) antenna for cognitive radio MIMO applications to avoid the complexities involved in reconfigurable antennas and improve the spectrum utilization efficiency.

Design/methodology/approach

The proposed MIMO antenna system comprises a wideband antenna that operates at 2 GHz–12 GHz for sensing the spectrum and four pairs of antennas for communication, which are single and dual-band antennas. Each pair of antennas meant for communication consists of two similar antennas. Moreover, the antennas meant for communication cover 93% of the bandwidth of the sensing antenna.

Findings

The first pair of antennas accessible at ports P2 and P6 and the second pair of antennas accessible at ports P4 and P8, which are dual-band antennas, operate at 3.05 GHz–3.85 GHz, 5.8 GHz–8 GHz and 2.05 GHz–2.55 GHz, 4.7 GHz–6.1 GHz, respectively. While the third pair of antennas accessible at ports P3 and P7 and the fourth pair of antennas accessible at ports P5 and P9 are single-band antennas and operate at 3.85 GHz–4.7 GHz and 8 GHz–11 GHz, respectively. Minimum isolations of 20 dB and 15 dB are attained between every two similar antennas for communication and between the sensing antenna and the antennas meant for communication, respectively. The correctness of the proposed antenna is verified with a fine match between the results obtained from simulations and measurements.

Originality/value

The proposed MIMO antenna possesses salient features, such as polarization diversity and performing a maximum of four communication tasks when all the white spaces are detected.

Details

Circuit World, vol. 48 no. 1
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 6 July 2023

Iqra Masroor and Jamshed Aslam Ansari

Compact and wideband antennas are the need of modern wireless systems that preferably work with compact, low-profile and easy-to-install devices that provide a wider coverage of…

84

Abstract

Purpose

Compact and wideband antennas are the need of modern wireless systems that preferably work with compact, low-profile and easy-to-install devices that provide a wider coverage of operating frequencies. The purpose of this paper is to propose a novel compact and ultrawideband (UWB) microstrip patch antenna intended for high frequency wireless applications.

Design/methodology/approach

A square microstrip patch antenna was initially modeled on finite element method-based electromagnetic simulation tool high frequency structure simulator. It was then loaded with a rectangular slit and Koch snowflake-shaped fractal notches for bandwidth enhancement. The fabricated prototype was tested by using vector network analyzer from Agilent Technologies, N5247A, Santa Clara, California, United States (US).

Findings

The designed Koch fractal patch antenna is highly compact with dimensions of 10 × 10 mm only and possesses UWB characteristics with multiple resonances in the operating band. The −10 dB measured impedance bandwidth was observed to be approximately 13.65 GHz in the frequency range (23.20–36.85 GHz).

Originality/value

Owing to its simple and compact structure, positive and substantial gain values, high radiation efficiency and stable radiation patterns throughout the frequency band of interest, the proposed antenna is a suitable candidate for high frequency wireless applications in the K (18–27 GHz) and Ka (26.5–40 GHz) microwave bands.

Details

Microelectronics International, vol. 41 no. 3
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 30 July 2024

Srikar Sarma Kona, Navdeep Sharma Dugala and Gurmeet Singh

This study aims to investigate the erosion wear rate of a stainless steel automobile exhaust manifold, both computationally and physically.

11

Abstract

Purpose

This study aims to investigate the erosion wear rate of a stainless steel automobile exhaust manifold, both computationally and physically.

Design/methodology/approach

The experiment was performed on a motorcycle exhaust manifold as well as on a 3D model, created using SolidWorks 2022 CAD software. The analysis was later achieved using ANSYS 19.2 simulation software using Fluent – code.

Findings

The analysis of solid particle erosion in the exhaust manifold revealed that erosion wear is concentrated predominantly at the extrados of the manifold, with the most significant wear occurring at the lowermost bend. The erosion wear rate increases with larger particulate sizes and varies among bends, with negligible wear observed in straight pipes. The SEM analysis further confirmed surface degradation, with rugged textures, pits and grooves indicating abrasive wear. Spine-like structures and fractured soot particles suggest erosive and abrasive forces caused by high-speed contact of exhaust gas compounds. Energy dispersive X-ray spectroscopy revealed significant carbon abundance, indicating carbonaceous compounds from fuel combustion, along with notable amounts of oxygen and iron, typical of oxidized metallic constituents. The discrete phase modeling (DPM) analysis highlighted peak particulate matter deposition at the first bend exit, with maximum concentrations observed at specific angles. This deposition is influenced by centrifugal force, leading to increased PM concentration at outer bend walls. Velocity magnitude contours showed asymmetrical flow profiles, with high turbulence levels and secondary flow induced by centrifugal effects in bend areas. Dynamic pressure contours revealed varying pressures at intrados and extrados, with maximum pressure observed at the intrados of the manifold’s bends. These findings provide valuable insights into erosion wear, particulate dispersion and flow dynamics within the exhaust manifold.

Originality/value

The study investigated an automobile exhaust manifold model using ANSYS Fluent code and DPM to analyze erosion wear rate phenomena and its various constituents. This analysis was conducted in comparison with a physically eroded sample. The study offers insights into the mechanism underlying the exhaust manifold of an automobile.

Details

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

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Article
Publication date: 6 July 2021

Phaneendra Kumar Kopparthi, Srikar Gemaraju, Bhaskara Rao Pathakokila and Suresh Gamini

Delamination is a common and crucial damage mode which occurs during manufacturing of layered composites or their service life. Its existence leads to degradation in mechanical…

176

Abstract

Purpose

Delamination is a common and crucial damage mode which occurs during manufacturing of layered composites or their service life. Its existence leads to degradation in mechanical properties or even structural failure of composites. Hence, the purpose of this article is to study the effect of induced delamination on flexural performance of CFRP composites.

Design/methodology/approach

In this article, the flexural behaviors of intact and delaminated carbon/epoxy laminates were investigated under pure bending. A circular PTFE film was introduced during fabrication to create artificial delamination. Moreover, finite element models were developed for intact and delaminated composites using ANSYS. The created models were discretized using 3D structural eight node solid elements.

Findings

The delamination influenced considerably flexural properties of composite. The composite exhibited a linear elastic nature prior to the damage of top ply on the compression side. The flexural strength and stiffness of the composite reduced to 44.5% and 18.2% respectively due to the existence of artificial delamination. The results of four point bending experiments and finite element analysis agreed for both intact and delaminated composites within acceptable error. Finally for same composites, first ply failure analysis was carried out using Tsai-Hill, Tsai-Wu and Hashin failure criteria.

Originality/value

In pure bending, beam section of the middle portion is free from shear. It is not so in case of three-point bending. Hence, the effect of embedded artificial defect on bending performance of CFRP composite due to pure bending has been investigated.

Details

Multidiscipline Modeling in Materials and Structures, vol. 17 no. 5
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 26 August 2024

Amin Eidi and Sakineh Zeynali

The effect of viscosity on the performance of disk-shaped electromechanical resonators has been studied and investigated in the past. The vibration frequency of a disk-shaped…

21

Abstract

Purpose

The effect of viscosity on the performance of disk-shaped electromechanical resonators has been studied and investigated in the past. The vibration frequency of a disk-shaped resonator changes according to the viscosity of the liquid which the resonator is in contact with. Therefore, the purpose of this paper is based on design a sensor for measuring the viscosity of liquids using a disk-shaped electromechanical resonator. The viscosity of liquids is of interest to researchers in industry and medicine.

Design/methodology/approach

In this paper, a viscosity sensor for liquids is proposed, which is designed based on a disk-shaped electromechanical resonator. In this proposed sensor, two comb drives are used as electrostatic actuators to stimulate the resonator. Also, two other comb drives are used as electrostatic sensors to monitor the frequency changes of the proposed resonator. The resonance frequency of the resonator in response to different fluids under test varies according to their viscosity.

Findings

After calibration of the proposed sensor by nonlinear weights, the viscosity of some liquids are calculated using this sensor and results confirm its accuracy according to the liquids real viscosity.

Originality/value

The design of the proposed sensor and its simulated performance are reported. Also, the viscosity of several different liquids are evaluated with simulations of the proposed sensor and presented.

Details

Sensor Review, vol. 44 no. 6
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 3 October 2019

Dharmendra B.V., Shyam Prasad Kodali and Nageswara Rao Boggarapu

The purpose of this paper is to adopt the multi-objective optimization technique for identifying a set of optimum abrasive water jet machining (AWJM) parameters to achieve maximum…

207

Abstract

Purpose

The purpose of this paper is to adopt the multi-objective optimization technique for identifying a set of optimum abrasive water jet machining (AWJM) parameters to achieve maximum material removal rate (MRR) and minimum surface roughness.

Design/methodology/approach

Data of a few experiments as per the Taguchi’s orthogonal array are considered for achieving maximum MRR and minimum surface roughness (Ra) of the Inconel718. Analysis of variance is performed to understand the statistical significance of AWJM input process parameters.

Findings

Empirical relations are developed for MRR and Ra in terms of the AWJM process parameters and demonstrated their adequacy through comparison of test results.

Research limitations/implications

The signal-to-noise ratio transformation should be applied to take in to account the scatter in the repetition of tests in each test run. But, many researchers have adopted this transformation on a single output response of each test run, which has no added advantage other than additional computational task. This paper explains the impact of insignificant process parameter in selection of optimal process parameters. This paper demands drawbacks and complexity in existing theories prior to use new algorithms.

Practical implications

Taguchi approach is quite simple and easy to handle optimization problems, which has no practical implications (if it handles properly). There is no necessity to hunt for new algorithms for obtaining solution for multi-objective optimization AWJM process.

Originality/value

This paper deals with a case study, which demonstrates the simplicity of the Taguchi approach in solving multi-objective optimization problems with a few number of experiments.

Details

Multidiscipline Modeling in Materials and Structures, vol. 16 no. 2
Type: Research Article
ISSN: 1573-6105

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Book part
Publication date: 20 May 2017

Dean R. Lillard

I investigate the well-known educational gradient in smoking. It is well established that, at least in recent decades, people with higher levels of education are less likely to…

Abstract

I investigate the well-known educational gradient in smoking. It is well established that, at least in recent decades, people with higher levels of education are less likely to smoke and, conditional on being a smoker, are more likely to quit than are people with less education. Using longitudinal data on lifetime smoking histories, I explore whether the educational gradient changes when one accounts for differences in the amount of information smokers have about the health risks associated with smoking. At the core of the analysis is a new way to measure not only the flow of information a person receives but also a person’s stock of information in any year. I construct measures of the stock and flow of information with consumer magazine articles that discuss cigarette smoking and health. To calculate exposure, I predict individuals’ reading of particular magazines and link predicted exposure to data on individual smoking status in every year of life. The analysis sample includes many individuals who started smoking in the 1930s and 1940s – well before scientific evidence had accumulated. After replicating the education gradient in terms of smoking cessation, I show that it is mostly explained by the interaction between educational attainment and the stock of knowledge individuals possess. The findings suggest that education affects whether and how a stock of health risk information induces people to quit smoking.

Details

Human Capital and Health Behavior
Type: Book
ISBN: 978-1-78635-466-2

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Article
Publication date: 3 January 2017

Peyman Rafiee, Golta Khatibi and Michael Zehetbauer

The purpose of this paper is to provide an overview of the major reliability issues of microelectromechanical systems (MEMS) under mechanical and environmental loading conditions…

1155

Abstract

Purpose

The purpose of this paper is to provide an overview of the major reliability issues of microelectromechanical systems (MEMS) under mechanical and environmental loading conditions. Furthermore, a comprehensive study on the nonlinear behavior of silicon MEMS devices is presented and different aspects of this phenomenon are discussed.

Design/methodology/approach

Regarding the reliability investigations, the most important failure aspects affecting the proper operation of the MEMS components with focus on those caused by environmental and mechanical loads are reviewed. These studies include failures due to fatigue loads, mechanical vibration, mechanical shock, humidity, temperature and particulate contamination. In addition, the influence of squeeze film air damping on the dynamic response of MEMS devices is briefly discussed. A further subject of this paper is discussion of studies on the nonlinearity of silicon MEMS. For this purpose, after a description of the basic principles of nonlinearity, the consequences of nonlinear phenomena such as frequency shift, hysteresis and harmonic generation and their effects on the device performance are reviewed. Special attention is paid to the mode coupling effect between the resonant modes as a result of energy transfer because of the nonlinearity of silicon. For a better understanding of these effects, the nonlinear behavior of silicon is demonstrated by using the example of Si cantilever beams.

Findings

It is shown that environmental and mechanical loads can influence on proper operation of the MEMS components and lead to early fracture. In addition, it is demonstrated that nonlinearity modifies dynamic response and leads to new phenomena such as frequency shift and mode coupling. Finally, some ideas are given as possible future areas of research works.

Originality/value

This is a review paper and aimed to review the latest manuscripts published in the field of reliability and nonlinearity of the MEMS structures.

Details

Microelectronics International, vol. 34 no. 1
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 5 October 2018

Bilal El Itani, Fouad Ben Abdelaziz and Hatem Masri

Ambulance response time is an important factor in saving lives and is highly linked with the ambulance location problem. The Maximum Expected Covering Location Problem (MEXCLP)…

453

Abstract

Purpose

Ambulance response time is an important factor in saving lives and is highly linked with the ambulance location problem. The Maximum Expected Covering Location Problem (MEXCLP), introduced by Daskin (1983), is one of the most used ambulance location models that maximize the probability of stratifying demands for emergency medical service (EMS) centers. Due to huge increase in the operational costs of EMS centers, ambulance location models must consider the cost of coverage and the opportunity to use other companies’ private ambulances to answer emergency calls. The paper aims to discuss these issues.

Design/methodology/approach

In this paper, the authors propose to extend the MEXCLP to a bi-objective optimization problem where the cost of satisfying emergency calls is minimized.

Findings

The proposed model is tested using data retrieved from the Lebanese Red Cross (LRC) in Beirut capital of Lebanon. The reported findings show significant enhancements in the results where the LRC can fully satisfy the perceived demands from all areas in Beirut within 9 min with an affordable cost.

Originality/value

The model is a first attempt to reduce operational costs of EMS centers while constraining the response time to satisfy emergency calls at an acceptable rate.

Details

Management Decision, vol. 57 no. 2
Type: Research Article
ISSN: 0025-1747

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Article
Publication date: 28 September 2010

Wen‐Jinn Chen

In practical environments, machines subject to maintenance are prevalent in many production systems. This paper aims to find a schedule that minimizes the completion time (or…

949

Abstract

Purpose

In practical environments, machines subject to maintenance are prevalent in many production systems. This paper aims to find a schedule that minimizes the completion time (or equivalently, the total setup time) subject to maintenance and due dates.

Design/methodology/approach

An efficient heuristic is presented to provide the near‐optimal solution for the problem. The performance of the heuristic is evaluated by comparing its solution with the optimal solution obtained from the integer linear programming model.

Findings

In many production systems, the sequence‐dependent setup time of a job cannot be ignored when a switch between two different jobs occurs. The paper studies the sequence‐dependent setup time problem with periodic maintenance, where several maintenances are required. Computational results show that problems with larger time interval and smaller maintaining time can produce a smaller completion time.

Practical implications

Here an efficient heuristic is developed to provide the near‐optimal schedule for the problem. The proposed integer linear programming model is also presented to provide the optimal schedule. However, the proposed heuristic and the integer linear programming model developed in the paper are appropriate for those companies where maintenance is performed periodically and the sequence‐dependent setup times of their jobs are required.

Originality/value

The paper presents the heuristic and the integer linear programming model to deal with sequencing and maintenance problems.

Details

Journal of Quality in Maintenance Engineering, vol. 16 no. 4
Type: Research Article
ISSN: 1355-2511

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