Technologies

488 KiB

Open AccessArticle

Improved Decision Fusion Model for Wireless Sensor Networks over Rayleigh Fading Channels

by Ali Jamoos

Technologies 2017, 5(1), 10; https://doi.org/10.3390/technologies5010010 - 10 Mar 2017

Cited by 3 | Viewed by 5120

This paper deals with decision fusion in wireless sensor networks (WSNs) over Rayleigh fading channels. The likelihood ratio test (LRT) is considered as the optimal fusion rule when applied at the fusion center (FC). However, applying the LRT at the FC requires both [...] Read more.

This paper deals with decision fusion in wireless sensor networks (WSNs) over Rayleigh fading channels. The likelihood ratio test (LRT) is considered as the optimal fusion rule when applied at the fusion center (FC). However, applying the LRT at the FC requires both the channel state information (CSI) and the local sensors’ performance indices. Acquiring such information is considered as an overhead in energy and bandwidth constrained systems such as WSNs. To avoid these drawbacks, we propose a modiﬁcation to the traditional three-layer system model of a WSN where the LRT is applied as a local decision making method at the sensors level. Applying the LRT at the sensors level does not require the CSI or the local sensors’ performance indices. It only requires the signal-to-noise ratio (SNR). Moreover, a new fusion rule based on selection combining (SC) is suggested. This fusion method has the lowest complexity when compared to other diversity combining based fusion rules such as the equal gain combiner (EGC) and the maximum ratio combiner (MRC). Simulation results show that the performance of the proposed model outperforms the traditional model. In addition, applying the EGC at the FC in the proposed model provides comparable performance to the traditional model that applies the LRT at the FC. Full article

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3216 KiB

Open AccessArticle

In-Built Customised Mechanical Failure of 316L Components Fabricated Using Selective Laser Melting

by Andrei Ilie, Haider Ali and Kamran Mumtaz

Technologies 2017, 5(1), 9; https://doi.org/10.3390/technologies5010009 - 25 Feb 2017

Cited by 19 | Viewed by 6043

Abstract

The layer-by-layer building methodology used within the powder bed process of Selective Laser Melting facilitates control over the degree of melting achieved at every layer. This control can be used to manipulate levels of porosity within each layer, effecting resultant mechanical properties. If [...] Read more.

The layer-by-layer building methodology used within the powder bed process of Selective Laser Melting facilitates control over the degree of melting achieved at every layer. This control can be used to manipulate levels of porosity within each layer, effecting resultant mechanical properties. If specifically controlled, it has the potential to enable customisation of mechanical properties or design of in-built locations of mechanical fracture through strategic void placement across a component, enabling accurate location specific predictions of mechanical failure for fail-safe applications. This investigation examined the process parameter effects on porosity formation and mechanical properties of 316L samples whilst maintaining a constant laser energy density without manipulation of sample geometry. In order to understand the effects of customisation on mechanical properties, samples were manufactured with in-built porosity of up to 3% spanning across ~1.7% of a samples’ cross-section using a specially developed set of “hybrid” processing parameters. Through strategic placement of porous sections within samples, exact fracture location could be predicted. When mechanically loaded, these customised samples exhibited only ~2% reduction in yield strength compared to samples processed using single set parameters. As expected, microscopic analysis revealed that mechanical performance was closely tied to porosity variations in samples, with little or no variation in microstructure observed through parameter variation. The results indicate that there is potential to use SLM for customising mechanical performance over the cross-section of a component. Full article

(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)

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1051 KiB

Open AccessArticle

Additive Manufacturing: Reproducibility of Metallic Parts

by Konda Gokuldoss Prashanth, Sergio Scudino, Riddhi P. Chatterjee, Omar O. Salman and Jürgen Eckert

Technologies 2017, 5(1), 8; https://doi.org/10.3390/technologies5010008 - 22 Feb 2017

Cited by 45 | Viewed by 8086

Abstract

The present study deals with the properties of five different metals/alloys (Al-12Si, Cu-10Sn and 316L—face centered cubic structure, CoCrMo and commercially pure Ti (CP-Ti)—hexagonal closed packed structure) fabricated by selective laser melting. The room temperature tensile properties of Al-12Si samples show good consistency [...] Read more.

The present study deals with the properties of five different metals/alloys (Al-12Si, Cu-10Sn and 316L—face centered cubic structure, CoCrMo and commercially pure Ti (CP-Ti)—hexagonal closed packed structure) fabricated by selective laser melting. The room temperature tensile properties of Al-12Si samples show good consistency in results within the experimental errors. Similar reproducible results were observed for sliding wear and corrosion experiments. The other metal/alloy systems also show repeatable tensile properties, with the tensile curves overlapping until the yield point. The curves may then follow the same path or show a marginal deviation (~10 MPa) until they reach the ultimate tensile strength and a negligible difference in ductility levels (of ~0.3%) is observed between the samples. The results show that selective laser melting is a reliable fabrication method to produce metallic materials with consistent and reproducible properties. Full article

(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)

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1212 KiB

Open AccessFeature PaperArticle

Emergence of Home Manufacturing in the Developed World: Return on Investment for Open-Source 3-D Printers

by Emily E. Petersen and Joshua Pearce

Technologies 2017, 5(1), 7; https://doi.org/10.3390/technologies5010007 - 9 Feb 2017

Cited by 107 | Viewed by 30123

Abstract

Through reduced 3-D printer cost, increased usability, and greater material selection, additive manufacturing has transitioned from business manufacturing to the average prosumer. This study serves as a representative model for the potential future of 3-D printing in the average American household by employing [...] Read more.

Through reduced 3-D printer cost, increased usability, and greater material selection, additive manufacturing has transitioned from business manufacturing to the average prosumer. This study serves as a representative model for the potential future of 3-D printing in the average American household by employing a printer operator who was relatively unfamiliar with 3-D printing and the 3-D design files of common items normally purchased by the average consumer. Twenty-six items were printed in thermoplastic and a cost analysis was performed through comparison to comparable, commercially available products at a low and high price range. When compared to the low-cost items, investment in a 3-D printer represented a return of investment of over 100% in five years. The simple payback time for the high-cost comparison was less than 6 months, and produced a 986% return. Thus, fully-assembled commercial open source 3-D printers can be highly profitable investments for American consumers. Finally, as a preliminary gauge of the effect that widespread prosumer use of 3-D printing might have on the economy, savings were calculated based on the items’ download rates from open repositories. Results indicate that printing these selected items have already saved prosumers over $4 million by substituting for purchases. Full article

(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)

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Graphical abstract

5254 KiB

Open AccessArticle

Wireless Accelerometer for Neonatal MRI Motion Artifact Correction

by Martyn Paley, Steven Reynolds, Nurul Ismail, Mari Herigstad, Deborah Jarvis and Paul Griffiths

Technologies 2017, 5(1), 6; https://doi.org/10.3390/technologies5010006 - 22 Jan 2017

Cited by 3 | Viewed by 9824

Abstract

A wireless accelerometer has been used in conjunction with a dedicated 3T neonatal MRI system installed on a Neonatal Intensive Care Unit to measure in-plane rotation which is a common problem with neonatal MRI. Rotational data has been acquired in real-time from phantoms [...] Read more.

A wireless accelerometer has been used in conjunction with a dedicated 3T neonatal MRI system installed on a Neonatal Intensive Care Unit to measure in-plane rotation which is a common problem with neonatal MRI. Rotational data has been acquired in real-time from phantoms simultaneously with MR images which shows that the wireless accelerometer can be used in close proximity to the MR system. No artifacts were observed on the MR images from the accelerometer or from the MR system on the accelerometer output. Initial attempts to correct the raw data using the measured rotational angles have been performed, but further work will be required to make a robust correction algorithm. Full article

(This article belongs to the Special Issue Medical Imaging & Image Processing Ⅱ)

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155 KiB

Open AccessEditorial

Acknowledgement to Reviewers of Technologies in 2016

by Technologies Editorial Office

Technologies 2017, 5(1), 5; https://doi.org/10.3390/technologies5010005 - 10 Jan 2017

Viewed by 3693

Abstract

The editors of Technologies would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article

9451 KiB

Open AccessArticle

Tribological Behavior of Spark Plasma Sintered Aluminum-Graphene Composites at Room and Elevated Temperatures

by Sara Rengifo, Cheng Zhang, Sandip Harimkar, Benjamin Boesl and Arvind Agarwal

Technologies 2017, 5(1), 4; https://doi.org/10.3390/technologies5010004 - 3 Jan 2017

Cited by 22 | Viewed by 6444

Abstract

This study examines the role of Graphene nanoplatelets (GNPs) as a solid lubricant additive to aluminum. Pure Al and Al-2 vol % GNP pellets are sintered by Spark Plasma Sintering (SPS). Their tribological properties are evaluated by a ball-on-disk tribometer at room temperature [...] Read more.

This study examines the role of Graphene nanoplatelets (GNPs) as a solid lubricant additive to aluminum. Pure Al and Al-2 vol % GNP pellets are sintered by Spark Plasma Sintering (SPS). Their tribological properties are evaluated by a ball-on-disk tribometer at room temperature (RT) and high temperature (200 °C). Al-2 vol % GNP composite displayed poor densification (91%) and low hardness, resulting in poor wear resistance as compared to pure Al. However GNP addition resulted in a lower coefficient of friction (COF) as compared to pure aluminum at both temperatures. The results demonstrated that GNPs contribute to reducing COF by forming a protective tribolayer. GNPs also play a unique role in reducing oxygen ingress at 200 °C. It is concluded that the packing density of a starting powder blend of Al-GNP needs to be improved by using irregular shaped aluminum powder mixed with both larger and smaller GNPs. This would result in greater densification and improve wear rate while maintaining low COF. Full article

(This article belongs to the Special Issue Spark Plasma Sintering of Materials)

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7044 KiB

Open AccessReview

Tool Wear and Life Span Variations in Cold Forming Operations and Their Implications in Microforming

by Anders E. W. Jarfors, Sylvie J. Castagne, Atsushi Danno and Xinping Zhang

Technologies 2017, 5(1), 3; https://doi.org/10.3390/technologies5010003 - 27 Dec 2016

Cited by 15 | Viewed by 7089

Abstract

The current paper aims to review tooling life span, failure modes and models in cold microforming processes. As there is nearly no information available on tool-life for microforming the starting point was conventional cold forming. In cold forming common failures are (1) over [...] Read more.

The current paper aims to review tooling life span, failure modes and models in cold microforming processes. As there is nearly no information available on tool-life for microforming the starting point was conventional cold forming. In cold forming common failures are (1) over stressing of the tool; (2) abrasive wear; (3) galling or adhesive wear, and (4) fatigue failure. The large variation in tool life observed in production and how to predict this was reviewed as this is important to the viability of microforming based on that the tooling cost takes a higher portion of the part cost. Anisotropic properties of the tool materials affect tool life span and depend on both the as-received and in-service conditions. It was concluded that preconditioning of the tool surface, and coating are important to control wear and fatigue. Properly managed, the detrimental effects from surface particles can be reduced. Under high stress low-cycle fatigue conditions, fatigue failure form internal microstructures and inclusions are common. To improve abrasive wear resistance larger carbides are commonly the solution which will have a negative impact on tooling life as these tend to be the root cause of fatigue failures. This has significant impact on cold microforming. Full article

(This article belongs to the Special Issue Advanced Manufacturing Technologies for Novel Microstructures and Components Shapes)

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10383 KiB

Open AccessArticle

Agustin de Betancourt’s Wind Machine for Draining Marshy Ground: Approach to Its Geometric Modeling with Autodesk Inventor Professional

by José Ignacio Rojas-Sola and Eduardo De la Morena-de la Fuente

Technologies 2017, 5(1), 2; https://doi.org/10.3390/technologies5010002 - 26 Dec 2016

Cited by 14 | Viewed by 5796

Abstract

The present study shows the process followed in making the three-dimensional model and geometric documentation of a historical invention of the renowned Spanish engineer Agustin de Betancourt y Molina, which forms part of his rich legacy. Specifically, this was a wind machine for [...] Read more.

The present study shows the process followed in making the three-dimensional model and geometric documentation of a historical invention of the renowned Spanish engineer Agustin de Betancourt y Molina, which forms part of his rich legacy. Specifically, this was a wind machine for draining marshy ground, designed in 1789. The present research relies on the computer-aided design (CAD) techniques using Autodesk Inventor Professional software, based on the scant information provided by the only two drawings of the machine, making it necessary to propose a number of dimensional and geometric hypotheses as well as a series of movement restrictions (degrees of freedom), to arrive at a consistent design. The results offer a functional design for this historic invention. Full article

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1994 KiB

Open AccessReview

Quantum Sensing of Noisy and Complex Systems under Dynamical Control

by Gershon Kurizki, Gonzalo A. Alvarez and Analia Zwick

Technologies 2017, 5(1), 1; https://doi.org/10.3390/technologies5010001 - 24 Dec 2016

Cited by 7 | Viewed by 6318

Abstract

We review our unified optimized approach to the dynamical control of quantum-probe interactions with noisy and complex systems viewed as thermal baths. We show that this control, in conjunction with tools of quantum estimation theory, may be used for inferring the spectral and [...] Read more.

We review our unified optimized approach to the dynamical control of quantum-probe interactions with noisy and complex systems viewed as thermal baths. We show that this control, in conjunction with tools of quantum estimation theory, may be used for inferring the spectral and spatial characteristics of such baths with high precision. This approach constitutes a new avenue in quantum sensing, dubbed quantum noise spectroscopy. Full article

(This article belongs to the Special Issue Quantum Metrology)

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Technologies, Volume 5, Issue 1 (March 2017) – 10 articles

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