Open AccessArticle
Improved Decision Fusion Model for Wireless Sensor Networks over Rayleigh Fading Channels
Technologies 2017, 5(1), 10; doi:10.3390/technologies5010010 -
Abstract
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
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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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Open AccessArticle
In-Built Customised Mechanical Failure of 316L Components Fabricated Using Selective Laser Melting
Technologies 2017, 5(1), 9; doi:10.3390/technologies5010009 -
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
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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
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Open AccessArticle
Additive Manufacturing: Reproducibility of Metallic Parts
Technologies 2017, 5(1), 8; doi:10.3390/technologies5010008 -
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
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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
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Open AccessFeature PaperArticle
Emergence of Home Manufacturing in the Developed World: Return on Investment for Open-Source 3-D Printers
Technologies 2017, 5(1), 7; doi:10.3390/technologies5010007 -
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
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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
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Open AccessArticle
Wireless Accelerometer for Neonatal MRI Motion Artifact Correction
Technologies 2017, 5(1), 6; doi:10.3390/technologies5010006 -
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
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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
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Open AccessEditorial
Acknowledgement to Reviewers of Technologies in 2016
Technologies 2017, 5(1), 5; doi:10.3390/technologies5010005 -
Abstract The editors of Technologies would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2016.[...] Full article
Open AccessArticle
Tribological Behavior of Spark Plasma Sintered Aluminum-Graphene Composites at Room and Elevated Temperatures
Technologies 2017, 5(1), 4; doi:10.3390/technologies5010004 -
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
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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
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Open AccessReview
Tool Wear and Life Span Variations in Cold Forming Operations and Their Implications in Microforming
Technologies 2017, 5(1), 3; doi:10.3390/technologies5010003 -
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
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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
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Open AccessArticle
Agustin de Betancourt’s Wind Machine for Draining Marshy Ground: Approach to Its Geometric Modeling with Autodesk Inventor Professional
Technologies 2017, 5(1), 2; doi:10.3390/technologies5010002 -
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
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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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Open AccessReview
Quantum Sensing of Noisy and Complex Systems under Dynamical Control
Technologies 2017, 5(1), 1; doi:10.3390/technologies5010001 -
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
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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
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Open AccessTechnical Note
Deriving an Indoor Environmental Index for Portuguese Office Buildings
Technologies 2016, 4(4), 40; doi:10.3390/technologies4040040 -
Abstract
In 2002, the European Commission (EU) issued a Directive aiming to reduce the energy consumption of buildings, which was adopted by the EU member states and came into force in 2006. Portugal adopted it by issuing law decrees in 2006 which considered not
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In 2002, the European Commission (EU) issued a Directive aiming to reduce the energy consumption of buildings, which was adopted by the EU member states and came into force in 2006. Portugal adopted it by issuing law decrees in 2006 which considered not only the energy saving aspects but also additional specific measures aiming to protect indoor air quality (IAQ). This new legislation is now being enforced, and it will be necessary to define compliance acceptance levels for the prescribed indoor air limits. The use of comfort or environmental indexes could be of considerable help to ameliorate the evaluation of IAQ. This paper presents a proposal of an index regarding IAQ which considers both the aspects of thermal comfort and non-toxicity. The proposed index was calculated for offices of several European countries, available from previous studies and for Portugal as well. Bearing in mind there is few existing data, this study is consistent with the proposed index, as the obtained values are similar to Greece, which has several similarities with the Portuguese situation. Full article
Open AccessArticle
The Physics of Turbulence-Free Ghost Imaging
Technologies 2016, 4(4), 39; doi:10.3390/technologies4040039 -
Abstract
Since its first experimental demonstration, ghost imaging has attracted a great deal of attention due to interests in its fundamental nature and its potential applications. In terms of applications, the most interesting and useful feature, perhaps, is the turbulence insensitivity of thermal light
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Since its first experimental demonstration, ghost imaging has attracted a great deal of attention due to interests in its fundamental nature and its potential applications. In terms of applications, the most interesting and useful feature, perhaps, is the turbulence insensitivity of thermal light ghost imaging, i.e., atmospheric turbulence would not have any influence on the ghost images of sunlight. Inspired by ghost imaging, a new type of camera is ready for turbulence-free imaging applications. This turbulence-free camera would be especially useful for long distance imaging, such as satellite imaging. How could fluctuations of thermal light produce an image? Why is it turbulence-free? This article addresses these questions. Full article
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Open AccessArticle
Tensile Properties of Al-12Si Fabricated via Selective Laser Melting (SLM) at Different Temperatures
Technologies 2016, 4(4), 38; doi:10.3390/technologies4040038 -
Abstract
Additive manufacturing processes such as selective laser melting (SLM) are attracting increasing attention and are regarded as the manufacturing technology of the future, because of their ability to produce near net shaped components of theoretically any shape with added functionality. Various properties, including
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Additive manufacturing processes such as selective laser melting (SLM) are attracting increasing attention and are regarded as the manufacturing technology of the future, because of their ability to produce near net shaped components of theoretically any shape with added functionality. Various properties, including mechanical, tribological, welding, and corrosion properties, of Al-12Si alloys fabricated via SLM have been extensively studied. However, all of these studies were carried out at ambient conditions. Nevertheless, under working conditions, these alloys experience service temperatures ranging between 373 and 473 K. The present study focuses on the evaluation of the mechanical properties of SLM-fabricated Al-12Si alloys in this temperature range. For this, Al-12Si alloy specimens were annealed at 573 K, a temperature well beyond the test temperature in order to provide a stable microstructure during tensile testing. The plasticity of these materials increases along with the size of the dimples on the fracture surface with increasing tensile test temperature. Moreover, the annealed Al-12Si alloy exhibits appreciable tensile properties when tested between 373 K and 473 K. The results suggest that Al-12Si samples fabricated via SLM may be ideal candidates for automotive applications such as pistons and cylinder heads. Full article
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Open AccessArticle
Effect of Particle Size on Microstructure and Mechanical Properties of Al-Based Composite Reinforced with 10 Vol.% Mechanically Alloyed Mg-7.4%Al Particles
Technologies 2016, 4(4), 37; doi:10.3390/technologies4040037 -
Abstract
The effect of Mg-7.4%Al reinforcement particle size on the microstructure and mechanical properties in pure Al matrix composites was investigated. The samples were prepared by hot consolidation using 10 vol.% reinforcement in different size ranges, D, 0 < D < 20 µm (0–20
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The effect of Mg-7.4%Al reinforcement particle size on the microstructure and mechanical properties in pure Al matrix composites was investigated. The samples were prepared by hot consolidation using 10 vol.% reinforcement in different size ranges, D, 0 < D < 20 µm (0–20 µm), 20 ≤ D < 40 µm (20–40 µm), 40 ≤ D < 80 µm (40–80 µm) and 80 ≤ D < 100 µm (80–100 µm). The result reveals that particle size has a strong influence on the yield strength, ultimate tensile strength and percentage elongation. As the particle size decreases from 80 ≤ D < 100 µm to 0 < D < 20 µm, both tensile strength and ductility increases from 195 MPa to 295 MPa and 3% to 4% respectively, due to the reduced ligament size and particle fracturing. Wear test results also corroborate the size effect, where accelerated wear is observed in the composite samples reinforced with coarse particles. Full article
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Open AccessArticle
Mass Proportion, Bioactive Compounds and Antioxidant Capacity of Carrot Peel as Affected by Various Solvents
Technologies 2016, 4(4), 36; doi:10.3390/technologies4040036 -
Abstract
The aim of this study was to determine the mass proportion of carrot root and the effects of four various solvents (methanol, water, ethanol and hexane) on the contents of total phenolics and saponins as well as antioxidant capacity of carrot peel to
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The aim of this study was to determine the mass proportion of carrot root and the effects of four various solvents (methanol, water, ethanol and hexane) on the contents of total phenolics and saponins as well as antioxidant capacity of carrot peel to identify an optimal solvent for effective extraction of bioactive compounds from carrot peel for further investigation. The results showed that carrot root consisted of body, heads and peel with their mass proportion of 83.19%, 5.01% and 14.19% by fresh weight, respectively. Among four solvents tested, methanol obtained the highest levels of extraction yield (54.02% by dry weight), total phenolic content (9.02 mg GAE/g dry weight) and antioxidant capacity (DPPH radical scavenging capacity, cupric ion reducing antioxidant capacity, and ferric reducing antioxidant power) from carrot peel, while water extracted the highest content of saponins (272.9 mg EE/g dry weight) and possessed the maximum ABTS radical scavenging capacity. Therefore, methanol and water are considered for effective extraction of phenolics and saponins from carrot peel, respectively. The phenolic/saponin-enriched extracts are potential sources for further applications in the healthy food and/or pharmaceutical industries. Full article
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Open AccessArticle
Capturing the True Value of Assistive Technologies to Consumers in Routine Outcome Measurement
Technologies 2016, 4(4), 35; doi:10.3390/technologies4040035 -
Abstract
(1) Background: Recent reforms in Australia, providing people with disability and older people with choice and control over allocated funding, have altered consumer expectations and transformed the landscape of assistive technology (AT) service provision. The purpose of this study is to report on
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(1) Background: Recent reforms in Australia, providing people with disability and older people with choice and control over allocated funding, have altered consumer expectations and transformed the landscape of assistive technology (AT) service provision. The purpose of this study is to report on the routine AT outcomes of people who accessed an AT consultation service and examine how well these capture the impact of AT on their lives; (2) Methods: This study, which uses mixed methods for concurrent triangulation of the data, reports on the outcomes for 127 people who acquired a range of assistive technology in 2015 and examines the adequacy of an existing service outcome framework in capturing the true value of these technologies to AT users. Outcome data was routinely collected by a community service 2–4 months following an AT consultation. A telephone or face-to-face interview gathered demographic information as well as AT outcomes, using two standardized tools, the Individualized Prioritised Problem Assessment (IPPA) and the EATS 6D. Qualitative comments relating to the impact of the AT on the person’s life were also documented; (3) Results: The acquired AT generally met or exceeded expectations of the person using the AT and the attending health professional. Overall, people experienced decreased difficulty and increased feelings of autonomy, with most of the reported improvements identified in mobility and usual activities; (4) Conclusion: Routine outcome data provide some evidence of the value of AT in addressing concerns as identified by clients. Qualitative data, which captured the impact of AT on people’s lives, suggest that the empowering and transformative aspects of AT are not currently being captured by existing measures. Full article
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Open AccessArticle
Characterization of 316L Steel Cellular Dodecahedron Structures Produced by Selective Laser Melting
Technologies 2016, 4(4), 34; doi:10.3390/technologies4040034 -
Abstract
The compression behavior of different 316L steel cellular dodecahedron structures with different density values were studied. The 316L steel structures produced using the selective laser melting process has four different geometries: single unit cells with and without the addition of base plates beneath
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The compression behavior of different 316L steel cellular dodecahedron structures with different density values were studied. The 316L steel structures produced using the selective laser melting process has four different geometries: single unit cells with and without the addition of base plates beneath and on top, and sandwich structures with multiple unit cells with different unit cell sizes. The relation between the relative compressive strength and the relative density was compared using different Gibson-Ashby models and with other published reports. The different aspects of the deformation and the mechanical properties were evaluated and the deformation at distinct loading levels was recorded. Finite element method (FEM) simulations were carried out with the defined structures and the mechanical testing results were compared. The calculated theory, simulation estimation, and the observed experimental results are in good agreement. Full article
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Open AccessArticle
Mechanical and Corrosion Behavior of New Generation Ti-45Nb Porous Alloys Implant Devices
Technologies 2016, 4(4), 33; doi:10.3390/technologies4040033 -
Abstract
Strategies to improve the mechanical compatibility of Ti-based materials for hard tissue implant applications are directed towards significant stiffness reduction by means of the adjustment of suitable β-phases and porous device architectures. In the present study, the effect of different compaction routes of
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Strategies to improve the mechanical compatibility of Ti-based materials for hard tissue implant applications are directed towards significant stiffness reduction by means of the adjustment of suitable β-phases and porous device architectures. In the present study, the effect of different compaction routes of the gas-atomized β-Ti-45Nb powder on the sample architecture, porosity, and on resulting mechanical properties in compression was investigated. Green powder compacted and sintered at 1000 °C had a porosity varying between 8% and 12%, strength between 260 and 310 MPa, and Young’s modulus ranging between 18 and 21 GPa. Hot pressing of the powder without or with subsequent sintering resulted in microporosity varying between 1% and 3%, ultimate strength varying between 635 and 735 MPa, and Young’s modulus between 55 and 69 GPa. Samples produced with NaCl space-holder by hot-pressing resulted in a macroporosity of 45% and a high strength of ˃200 MPa, which is higher than the strength of a human cortical bone. Finally, the corrosion tests were carried out to prove that the presence of residual NaCl traces will not influence the performance of the porous implant in the human body. Full article
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Open AccessArticle
Interactions between the Ionic Liquid and the ZrO2 Support in Supported Ionic Liquid Membranes for CO2 Separation
Technologies 2016, 4(4), 32; doi:10.3390/technologies4040032 -
Abstract
This work reports the interaction study of two supported ionic liquid membranes (SILMs) based on 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), which were impregnated into porous zirconia supports with 20 nm average pore diameters.
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This work reports the interaction study of two supported ionic liquid membranes (SILMs) based on 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]), which were impregnated into porous zirconia supports with 20 nm average pore diameters. The interaction of ionic liquid-support observed from diffuse reflectance (DR), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) is reported. The IR spectrum in the 600 to 4000 cm−1 range showed a specific interaction of the ionic liquid with the support. The N2 and CO2 permeances in the SILMs with [C4mim][BF4] were 8.7 × 10−8 mol·s−1·m−2·Pa−1 and 9.6 × 10−7 mol·s−1·m−2·Pa−1, respectively. The separation factor through the ionic liquid in the membrane as a function of temperature showed that the SILMs studied here can be used for CO2 separation at low temperatures. Full article
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Open AccessArticle
Reactive Spark Plasma Sintering and Mechanical Properties of Zirconium Diboride–Titanium Diboride Ultrahigh Temperature Ceramic Solid Solutions
Technologies 2016, 4(3), 30; doi:10.3390/technologies4030030 -
Abstract
Ultrahigh temperature ceramics (UHTCs) such as diborides of zirconium, hafnium tantalum and their composites are considered to be the candidate materials for thermal protection systems of hypersonic vehicles due to their exceptional combination of physical, chemical and mechanical properties. A composite of ZrB
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Ultrahigh temperature ceramics (UHTCs) such as diborides of zirconium, hafnium tantalum and their composites are considered to be the candidate materials for thermal protection systems of hypersonic vehicles due to their exceptional combination of physical, chemical and mechanical properties. A composite of ZrB2-TiB2 is expected to have better properties. In this study, an attempt has been made to fabricate ZrB2-TiB2 ceramics using mechanically activated elemental powders followed by reactive spark plasma sintering (RSPS) at 1400 °C. Microstructure and phase analysis was carried out using X-ray diffractometer (XRD) and electron microscopy to understand microstructure evolution. Fracture toughness and hardness were evaluated using indentation methods. Nanoindentation was used to measure elastic modulus. Compressive strength of the composites has been reported. Full article
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