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Article
Publication date: 1 December 2003

F. Filser, P. Kocher and L.J. Gauckler

A new process called direct ceramic machining was successfully applied for the fabrication of dental restorations and technical components. It uses prefabricated, easy to…

Abstract

A new process called direct ceramic machining was successfully applied for the fabrication of dental restorations and technical components. It uses prefabricated, easy to machine ceramic blanks. The shape of a ceramic component is machined with enlarged contours to compensate for the sintering shrinkage. Afterwards the machined component is sintered to full density and thereby shrinks to its final dimensions. Technical components from 5 to 100 mm in size possessing features of 1/10th mm to several millimeters and dental restorations were fabricated sucessfully, and thus demonstrate the capability for rapid production of ceramic functional prototypes. The dimensional accuracy is about 20 μm with a relative accuracy of 0.1 per cent of the component's length. Thus accurate net‐shape of the components could be achieved without hard machining.

Details

Assembly Automation, vol. 23 no. 4
Type: Research Article
ISSN: 0144-5154

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Book part
Publication date: 5 August 2015

Abstract

Details

Airport Design and Operation
Type: Book
ISBN: 978-1-78441-869-4

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Article
Publication date: 29 April 2014

Siti Maisurah Mohd Hassan, Yusman M. Yusof, Arjuna Marzuki, Nazif Emran Farid, Siti Amalina Enche Ab Rahim and Mohd Hafis M. Ali

The purpose of this paper is to present the high-frequency performance of 0.13-μm n-type metal-oxide-semiconductor (NMOS) transistors with various multi-finger…

Abstract

Purpose

The purpose of this paper is to present the high-frequency performance of 0.13-μm n-type metal-oxide-semiconductor (NMOS) transistors with various multi-finger configurations for implementation in millimeter-wave (mm-wave) frequency.

Design/methodology/approach

A folded-like double-gate transistor layout is designed to enable the transistor to work in the mm-wave region. Different sizes of transistors with variation in finger width (WF ) and number of fingers (NF ) were fabricated to determine the optimum size of the transistor. The extrinsic parasitic elements of selected transistors were extracted and investigated. The radio frequency (RF) performance of these samples were then analyzed and compared.

Findings

The proposed layout performed well with the highest maximum oscillation frequency (fmax ) achieved at 122 GHz. Based on the comparison done, the optimum WF obtained for the layout is at 2.0 μm. It is found that the extrinsic parasitic capacitance is more dominant than the parasitic resistance in affecting the fmax . In s-parameter analysis, it is observed that the transistor with the least NF has smaller variance in small-signal gain throughout the measurement frequency. The maximum stable gain for the samples is also found to be roughly similar and independent of NF .

Originality/value

A new layout structure for an NMOS transistor that works in mm-wave frequency is proposed. Experimental analyses presented here cover for both NF and WF , unlike others which focus on either NF or WF only.

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Article
Publication date: 25 October 2019

Melvin C. Jose, Radha Sankararajan, Sreeja B.S. and Pratap Kumar

This paper aims to propose a laser micro-machined 4 × 4 elements microstrip array antenna suitable for 5 G millimeter wave (mm-wave) applications. Each patch element of…

Abstract

Purpose

This paper aims to propose a laser micro-machined 4 × 4 elements microstrip array antenna suitable for 5 G millimeter wave (mm-wave) applications. Each patch element of the array is excited with same amplitude and phase that is achieved with proper novel impedance matching stub. The proposed antenna achieves a simulated gain of 13.15 dBi and a measured return loss of −24.80 dB at 28.73 GHz with a total bandwidth of 7.48 GHz. The designed antenna is directional with a directivity of 15.1 dBi at 28.73 GHz, whereas fabricated on a low cost FR4 substrate with a substrate thickness of 0.074 λ mm. The antenna is realized with an aperture size of 2.24λ × 3.26λ.

Design/methodology/approach

The antenna structure starts from the design of single element called unit cell. The single element is designed using the transmission line model equations of a rectangular patch. To design a 28 GHz microstrip patch antenna, a dielectric material with lower permittivity and having thickness (h) less than 1 mm is required. This specification gives better gain and efficiency by reducing surface waves and mutual coupling between elements. The inset width is optimized to achieve the minimum reflection coefficient (S11). The single element has been arranged with a minimum spacing of λ/2 (5.3571 mm) in an H plane and E plane. It is connected using the microstrip lines with proper impedance matching. The four 2 × 2-sub array cell subsystems are connected with a corporate feed together formed the 4 × 4-array cell. Rectangular planar array method is used to arrange the elements in the 4 × 4 array cell.

Findings

The design concept is simple which includes the combination of corporate feed and insect feed. It is compact in size and easy to fabricate. The bandwidth of fabricated prototype antenna array is achieved as 7.48 GHz from 24.98 GHz to 32.46 GHz. The mutual coupling is very less though the antenna array is placed with minimum spacing between adjacent elements. This is because of the microstrip feeding structure with minimum phase shift. The gain can be further enhanced with increasing number of array element and proper designing of feed line. Owing to the advantages of low profile, wide bandwidth and high gain, the designed array will be potentially useful in 5 G wireless communications.

Originality/value

The measured antenna offers bandwidth 7.48 GHz (24.98 GHz-32.46 GHz) with centered frequency 28.73 GHz. The agreement between simulated and measured results is good. The VSWR is observed 0.32 < 2, offers good impedance matching and low mutual coupling. It gives better E-Field and H-field radiation patterns of the 4 × 4 array antenna structure at 28 GHz. The total gain of 13.14 dBi is achieved at the center frequency. The total efficiency of 63.42 per cent is achieved with FR4 substrate.

Details

Circuit World, vol. 46 no. 1
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 1 October 2019

Meltem Altin Karatas, Hasan Gokkaya and Muammer Nalbant

The aim of this paper is to optimize the machining parameters to obtain the smallest average surface roughness values during drilling of the carbon fiber-reinforced…

Abstract

Purpose

The aim of this paper is to optimize the machining parameters to obtain the smallest average surface roughness values during drilling of the carbon fiber-reinforced polymer (CFRP) composite material with abrasive water jet (AWJ) and analyze the damage of the delamination.

Design/methodology/approach

CFRP composite material had been fabricated having fiber orientations frequently used in the aerospace industry (0°/45°/90°/−45°). Three different stand-off distances (1, 2 and 3 mm), three different water pressures (1,800, 2,800 and 3,800 bar) and three different hole diameters (4, 8 and 12 mm) were selected as processing parameters. The average surface roughness values were obtained, and delamination damage was then analyzed using Taguchi optimization. Drilling experiments were performed using the Taguchi L27 orthogonal array via Minitab 17 software. The signal/noise ratio was taken into account in the evaluation of the test results. Using the Taguchi method, the control factors giving the mean surface roughness values were determined. Analysis of variance was performed using the experimental results, and the effect levels of the control factors on the average surface roughness were found.

Findings

It was found that water pressure and hole diameter had a higher effect on average surface roughness, while water pressure and stand-off distance were effective on delamination.

Practical implications

Owing to their excellent thermal and mechanical properties, the CFRP composite materials show greater potential for their applications in aircraft and aerospace industry.

Originality/value

The novel approach is to reduce cost and spent time using Taguchi optimization as a result of AWJ drilling the material in this fiber orientation ([0°/45°/90°/−45°]s, which is often used in the aerospace industry).

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 2
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 1 June 2004

Jan‐Mark Vorstenbosch, Fabien Bourgeois, Sandra Koelemeijer Chollet and Marcel Tichem

In this paper, a flexible solution for part feeding in assembly is analysed for its suitability to feed small parts with typical dimensions between 0.5 and 5.0 mm. The…

Abstract

In this paper, a flexible solution for part feeding in assembly is analysed for its suitability to feed small parts with typical dimensions between 0.5 and 5.0 mm. The feeding concept is based on a tooling plate, which vibrates to separate and reorient the parts. A vision system is used to determine the position of parts in a correct orientation. A robot picks these parts and assembles them. The conditions for a successful reorientation of parts are studied. The influence of adhesive forces on the ability to re‐orientate is investigated. A prototype is built to determine empirically the magnitude of the adhesive forces and the influence of these forces on the feeding process.

Details

Assembly Automation, vol. 24 no. 2
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 24 October 2018

Prashant Sahni, Savita Sharma and Baljit Singh

Meal left after extraction of microalgae functional compounds is not finding its application in food. Hence, present study was aimed for the development of the cookies…

Abstract

Purpose

Meal left after extraction of microalgae functional compounds is not finding its application in food. Hence, present study was aimed for the development of the cookies supplemented with meal of microalgae Chlorella sp. (Abca-17) obtained after solvent extraction of chlorophyll.

Design/methodology/approach

Cookies were prepared by substituting refined wheat flour (RWF) with microalgae meal (MM) at incorporation levels of 3, 6, 9 and 12 per cent. The effect of replacement of RWF with MM was analyzed on the pasting properties of the flour blends and physical, chemical, sensory and textural characteristics of the cookies.

Findings

MM exhibited high water and oil absorption capacity of 0.8 g/g and 1.2 g/g, respectively. Weight and thickness of the cookies increased, whereas the diameter, spread ratio and spread factor decreased with the increased proportion of meal in flour blends. The moisture and ash content (0.8-2.0 per cent) of the cookies increased, whereas fat content showed no pronounced variation. Sensory evaluation of cookies revealed no significant difference at 6 per cent level of incorporation and further supplementation resulted in dark colour and increased hardness. Texture profile analysis of cookies also revealed that the peak positive force for breaking the cookies increased (3115.6-7372.1 N) with increase in the level of incorporation of meal.

Practical implications

MM can be used in the development of the cookies at level of incorporation of 6 per cent and presents novice approach for utilization of bioprocessing waste.

Originality/value

The present study is a pioneer effort in demonstration of utilization of MM as alternate food ingredient. MM of Chlorella sp. (Abca-17) was characterized as food ingredient using physicochemical analysis and model food system using cookies.

Details

Nutrition & Food Science, vol. 49 no. 2
Type: Research Article
ISSN: 0034-6659

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Article
Publication date: 1 April 2006

George Stockman, Jayson Payne, Jermil Sadler and Dirk Colbry

To report on the evaluation of error of a face matching system consisting of a 3D sensor for obtaining the surface of the face, and a two‐stage matching algorithm that…

Abstract

Purpose

To report on the evaluation of error of a face matching system consisting of a 3D sensor for obtaining the surface of the face, and a two‐stage matching algorithm that matches the sensed surface to a model surface.

Design/methodology/approach

Rigid mannikin face that was, otherwise, fairly realistic was obtained, and several sensing and matching experiments were performed. Pose position, lighting and face color were controlled.

Findings

The combined sensor‐matching system typically reported correct face surface matches with trimmed RMS error of 0.5 mm or less for a generous volume of parameters, including roll, pitch, yaw, position, lighting, and facecolor. Error accelerated beyond this “approximately frontal” set of parameters. Mannikin results are compared to results with thousands of cases of real faces. The sensor accuracy is not a limiting component of the system, but supports the application well.

Practical implications

The sensor supports the application well (except for the current cost). Equal error rates achieved appear to be practical for face verification.

Originality/value

No similar report is known for sensing faces.

Details

Sensor Review, vol. 26 no. 2
Type: Research Article
ISSN: 0260-2288

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Article
Publication date: 26 February 2021

Lijun Meng, Xinyu Li and Xin Tan

A fiber Bragg grating (FBG) sensor was designed to measure the door gap of automobile bodies.

Abstract

Purpose

A fiber Bragg grating (FBG) sensor was designed to measure the door gap of automobile bodies.

Design/methodology/approach

The gap sensor was designed through a combination of the sliding wedge and cantilever beam, involving a magnetic force installation and arc structure of the force transmission point. Moreover, the sliding block adopted an anti-magnetic and wear-resistant material and the temperature compensation of the two FBGs was conducted. The magnetic force and contact stress of the sensor were examined to ensure that the sensor exhibited a certain magnetic attraction force and fatigue life. The performance of the gap sensor was examined experimentally.

Findings

The sensor could measure gaps with dimensions of 5 mm to 11 mm, with a sensitivity and measurement accuracy of 150.9 pm/mm and 0.0063% F.S., respectively. Moreover, the sensor exhibited a small gap sensitivity, with a repeatability error of 0.15%, anti-creep properties and magnetic interference abilities.

Originality/value

The sensor is compact and easy to install, as well as use for multiple sensor locations, with a maximum size of 43 mm, a mass of 26 g and installation type of magnetic suction. It can be used for high-precision static and dynamic measurements of the door inner clearance with a resolution of 0.013 mm to improve the efficiency of internal clearance on-line analysis and assembly quality inspection.

Details

Sensor Review, vol. 41 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Content available
Article
Publication date: 8 July 2019

Sharifatul Ain Binti Sharifuddin, Salwani Binti Ismail, Imran Abdullah, Irfan Mohamad and Javeed Shaikh Mohammed

Staphylococcus aureus (S. aureus), Klebsiella pneumoniae (K. pneumoniae) and Streptococcus pneumoniae (S. pneumoniae) are among the pathogens detected during Hajj…

Abstract

Purpose

Staphylococcus aureus (S. aureus), Klebsiella pneumoniae (K. pneumoniae) and Streptococcus pneumoniae (S. pneumoniae) are among the pathogens detected during Hajj pilgrimage known to cause pneumonia. This study aims to evaluate the antibacterial activity of activated carbon cloth (ACC) with Ag+ impregnated with zinc oxide nanoparticles (ZnO NPs) against these pathogens.

Design/methodology/approach

ZnO NPs were impregnated into ACC-Ag+ via layer-by-layer (LbL) self-assembly. Scanning electron microscope (SEM) was used to observe the fine surface morphological details of the ACC-Ag+-ZnO sheets. Antibacterial activity of the ACC-Ag+-ZnO sheets was evaluated using the disk-diffusion susceptibility assay. Allergy patch test was done to evaluate allergic reactions of the ACC-Ag+-ZnO sheets on human skin.

Findings

SEM micrographs showed successful impregnation of ZnO NPs into the ACC-Ag+ sheets. Disk-diffusion susceptibility assay results of ACC-Ag+-ZnO sheets against S. aureus, K. pneumoniae and S. pneumoniae showed good antibacterial activity; with 1.82 ± 0.13 mm zone of inhibition for S. pneumoniae, at a ZnO concentration of 0.78 mg mL-1. No signs of human skin irritation were observed throughout the allergy patch test.

Originality/value

Results indicate that ACC-Ag+-ZnO sheets could potentially be embedded within surgical face masks (pilgrims’ preferred) to reduce the risks involved with the transmission of respiratory tract infections during and after mass gatherings (e.g. Hajj/Umrah, Olympics).

Details

Research Journal of Textile and Apparel, vol. 23 no. 3
Type: Research Article
ISSN: 1560-6074

Keywords

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