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Technologies, Volume 5, Issue 2 (June 2017)

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Open AccessArticle Railway Continuous Prestressed Concrete Bridge Design in Ballastless Track Turnout Zones
Technologies 2017, 5(2), 11; doi:10.3390/technologies5020011
Received: 31 December 2016 / Revised: 17 March 2017 / Accepted: 23 March 2017 / Published: 30 March 2017
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Abstract
Laying ballastless track on railway bridges has the advantages of reducing the train noise problem, improving passenger comfort, and reducing track maintenance costs. Therefore, railway bridges with ballastless track have gradually turned into a major trend in railway systems all over the world.
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Laying ballastless track on railway bridges has the advantages of reducing the train noise problem, improving passenger comfort, and reducing track maintenance costs. Therefore, railway bridges with ballastless track have gradually turned into a major trend in railway systems all over the world. In Taiwan, railway bridges with ballastless track have been in use for many years, with ballastless track turnouts also starting to be constructed in recent years. Where railway bridges with ballastless track turnouts are located in urban areas, special consideration must be given to the road crossings and the use of continuous bridges in the turnout zones. Accordingly, there arise a number of difficulties related to the bridge configurations or the continuous length of bridges being excessively long. Often, such situations necessitate the use of extremely large-sized bridge piers in the bridge design, or create the risk of serious damage to the pier structure should insufficient attention be given to any of the factors. This article will take a continuous prestressed concrete bridge as an example. The prestressed concrete bridge must be absolutely continuous, be able to include ballastless track turnout zones, and meet the needs of crossing roads. For this example, the length of the continuous prestressed concrete bridge is over 300 m. This article will also discuss the configuration of a continuous prestressed concrete bridge of railway, and—through the analysis of track–bridge interaction and temperature detection—provides suggestions on the optimal configuration model of the continuous prestressed concrete bridges, which should allow improper configuration and possible structural damage to be avoided. Full article
(This article belongs to the Special Issue Construction Materials Technologies)
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Open AccessArticle Research and Application of a SCADA System for a Microgrid
Technologies 2017, 5(2), 12; doi:10.3390/technologies5020012
Received: 8 February 2017 / Revised: 8 March 2017 / Accepted: 29 March 2017 / Published: 31 March 2017
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Abstract
An effective Supervisory Control and Data Acquisition (SCADA) system can improve the reliability, safety and economic benefits of a microgrid operation. In this research, the lower central controller and upper WEB (World Wide Web) monitoring system are connected by the SCADA system, which
[...] Read more.
An effective Supervisory Control and Data Acquisition (SCADA) system can improve the reliability, safety and economic benefits of a microgrid operation. In this research, the lower central controller and upper WEB (World Wide Web) monitoring system are connected by the SCADA system, which is the hub of a microgrid intelligent monitoring platform. This system contains a set of specific functions programmed by Java as a middleware and can provide communication and control functions between the central controller and the upper monitoring system. For the sake of security and stability of the microgrid, the SCADA system realizes business processing on real-time data acquisition and storage, load balancing and resource recovery, concurrent security processing, and control instruction parsing and transmission. All those functions were tested and verified in actual operation. Full article
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Open AccessArticle Moveable Factories for Leapfrog Manufacturing in an Industrial Economy
Technologies 2017, 5(2), 13; doi:10.3390/technologies5020013
Received: 14 March 2017 / Revised: 30 March 2017 / Accepted: 31 March 2017 / Published: 1 April 2017
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Abstract
Moveable factories can enable leapfrogging of fixed industrial factories, and so make immediate contributions to global goals of more resilient sustainable manufacturing. Moveable factories bring into use diverse technological advances that reduce the number, size, and weight of machines needed to carry out
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Moveable factories can enable leapfrogging of fixed industrial factories, and so make immediate contributions to global goals of more resilient sustainable manufacturing. Moveable factories bring into use diverse technological advances that reduce the number, size, and weight of machines needed to carry out manufacturing operations at points of supply and/or demand. However, fixed industrial factories continue to be the principal focus for development and application of new manufacturing technologies. At the same time, fixed industrial factories continue to be seen by policy makers around the world as the default option for developing prosperity: rather than as an old fashioned production paradigm to be leapfrogged over. In this paper, findings are reported from a case study investigating potential for moveable factories to bring leapfrog manufacturing to an industrial economy. This case study comprised literature review, interviews, and theoretical analyses. Study findings indicate that organisations in an industrial economy will consider moveable factories if fixed factories are not feasible, practical, or viable. By contrast, potential for improved efficiency and flexibility may not be sufficient to motivate a shift away from fixed industrial factories. Full article
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Open AccessArticle Proximate Composition, Extraction, and Purification of Theobromine from Cacao Pod Husk (Theobroma Cacao L.)
Technologies 2017, 5(2), 14; doi:10.3390/technologies5020014
Received: 4 March 2017 / Revised: 29 March 2017 / Accepted: 30 March 2017 / Published: 2 April 2017
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Abstract
The aims of this study were to determine the proximate composition of cacao pod husk as well as the optimal conditions for extraction and purification of theobromine from cacao pod husk. The results indicated that cacao pod husk had high contents of moisture
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The aims of this study were to determine the proximate composition of cacao pod husk as well as the optimal conditions for extraction and purification of theobromine from cacao pod husk. The results indicated that cacao pod husk had high contents of moisture and carbohydrate (87.06% and 11.03% by fresh weight, respectively), but low contents of crude protein, crude lipid, and ash (0.31%, 0.12%, and 1.48% by fresh weight, respectively). The optimal conditions for extraction of theobromine from cacao pod husk were of 70% ethanol, with an extraction time of 90 min, and 1 as the number of extractions. A concentration of 10% by volume of 10% lead acetate solution was the best selection for purification of the crude extracts containing theobromine from cacao pod husk. Under these optimal conditions, theobromine content obtained from cacao pod husk was 6.79 mg/100 g dry weight. The finding from this study is a valuable contribution for obtaining theobromine from an abundant, inexpensive, renewable, and sustainable source for potential application in the nutraceutical, medical, and pharmaceutical industries. Full article
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Open AccessArticle Accelerated Detector Response Function in Squeezed Vacuum
Technologies 2017, 5(2), 17; doi:10.3390/technologies5020017
Received: 18 February 2017 / Revised: 12 April 2017 / Accepted: 19 April 2017 / Published: 20 April 2017
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Abstract
Casimir/squeezed vacuum breaks Lorentz symmetry, by allowing light to propagate faster than c. We looked at the possible transformation symmetry group such vacuum could obey. By solving the semi-classical Einstein field equation in squeezed vacuum, we have found that the background geometry
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Casimir/squeezed vacuum breaks Lorentz symmetry, by allowing light to propagate faster than c. We looked at the possible transformation symmetry group such vacuum could obey. By solving the semi-classical Einstein field equation in squeezed vacuum, we have found that the background geometry describes an Anti-deSitter (AdS) geometry. Therefore, the proper transformation symmetry group is the (A)dS group. One can describe quantum field theory in a finite volume as a quantum field theory (QFT) on AdS background, or vice versa. In particular, one might think of QFT vacuum on AdS as a QFT that posses a squeezed vacuum with boundary conditions proportional to R A d S 2 . Applying this correspondence to an accelerating detector-scalar field system, we notice at low acceleration the system is at equilibrium at ground state, however if the detector’s acceleration (a) is greater than a critical acceleration, the system experience a phase transition similar to Hawking-Page Phase transition at the detector gets excited, with equivalent temperature Θ = a 2 - R A d S 2 2 π . Full article
(This article belongs to the Special Issue Quantum Gravity Phenomenology and Experimental Implications)
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Open AccessArticle A Transportable Photovoltaic Power Generation System Utilizing a SiC Inverter and Spherical Si Solar Cells
Technologies 2017, 5(2), 18; doi:10.3390/technologies5020018
Received: 10 March 2017 / Revised: 19 April 2017 / Accepted: 19 April 2017 / Published: 21 April 2017
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Abstract
This paper reports a 100-W class transportable photovoltaic (PV) power generation system built with SiC power devices. Conventionally, studies on SiC power converters have mostly focused on multi-kW applications. In this paper, we have verified the feasibility of the SiC power devices for
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This paper reports a 100-W class transportable photovoltaic (PV) power generation system built with SiC power devices. Conventionally, studies on SiC power converters have mostly focused on multi-kW applications. In this paper, we have verified the feasibility of the SiC power devices for sub-kW PV power generation systems. The developed PV power generation system consisted of a spherical Si solar cell module, a 150-W SiC PV-inverter unit with maximum power point tracking (MPPT) function, and a 12-V Li-ion battery. The total weight of the system was just 4.3 kg. Conversion efficiencies of the MPPT charge controller and the direct current-alternating current converter reached 98.0% and 88.4%, respectively. The developed system exhibited stable output power characteristics, even when the weather conditions were fluctuated. These compactness, high efficiencies, and excellent stability clearly indicated the feasibility of SiC power devices even for sub-kW class PV power generation systems. This kind of system would be available for the applications where compactness and transportability are of tremendous importance. Full article
(This article belongs to the Section Environmental Technology)
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Open AccessArticle Measurement of Assistive Technology Outcomes Associated with Computer-Based Writing Interventions for Children and Youth with Disabilities
Technologies 2017, 5(2), 19; doi:10.3390/technologies5020019
Received: 30 January 2017 / Revised: 22 March 2017 / Accepted: 19 April 2017 / Published: 22 April 2017
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Abstract
Young people who have chronic disabilities use computer technologies and receive rehabilitation services to overcome functional limitations associated with writing activities. However, the functional impact of these specialized assistive technologies on the everyday lives of children is not clearly understood; in part due
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Young people who have chronic disabilities use computer technologies and receive rehabilitation services to overcome functional limitations associated with writing activities. However, the functional impact of these specialized assistive technologies on the everyday lives of children is not clearly understood; in part due to the lack of targeted outcome measures. This article describes the development and evaluation of the Family Impact of Assistive Technology Scale for Writing Interventions (FIATS-WI). The FIATS-WI is a multi-dimensional, parent-report questionnaire designed to measure child functioning and outcomes associated with computer-based writing interventions for children and youth aged 5–18 years. Participants included parents of children with writing-related disabilities who completed the questionnaire at home during one of two study phases. In the first phase, 121 eligible parents, out of 364 invited, completed a single administration of the questionnaire. In the second phase, 28 out of 33 eligible parents completed the FIATS-WI twice to assess its stability. Item and subscale correlations informed an item reduction plan, and Cronbach’s alpha and intraclass correlation coefficients provided acceptable estimates for internal consistency and test–retest reliability, respectively. Correlations between FIATS-WI scores and scores from a standardized home participation measure tested its convergent validity. The study provides emerging evidence for the FIATS-WI as a sound measure of computer-based writing technology outcomes for children and youth with disabilities. Full article
Open AccessArticle Compression Tests of ABS Specimens for UAV Components Produced via the FDM Technique
Technologies 2017, 5(2), 20; doi:10.3390/technologies5020020
Received: 5 April 2017 / Revised: 2 May 2017 / Accepted: 3 May 2017 / Published: 5 May 2017
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Abstract
Additive manufacturing has introduced a great step in the manufacturing process of consumer goods. Fused Deposition Modeling (FDM) and in particular 3D printers for home desktop applications are employed in the construction of prototypes, models and in general in non-structural objects. The aim
[...] Read more.
Additive manufacturing has introduced a great step in the manufacturing process of consumer goods. Fused Deposition Modeling (FDM) and in particular 3D printers for home desktop applications are employed in the construction of prototypes, models and in general in non-structural objects. The aim of this new work is to characterize this process in order to apply this technology in the construction of aeronautical structural parts when stresses are not excessive. An example is the construction of the PoliDrone UAV, a multicopter patented, designed and realized by researchers at Politecnico di Torino. For this purpose, a statistical characterization of the mechanical properties of ABS (Acrylonitrile Butadiene Styrene) specimens in compression tests is proposed in analogy with the past authors’ work about the tensile characterization of ABS specimens. A desktop 3D printer, including ABS filaments as the material, has been employed. ASTM 625 has been considered as the reference normative. A capability analysis has also been used as a reference method to evaluate the boundaries of acceptance for both mechanical and dimensional performances. The statistical characterization and the capability analysis are here proposed in an extensive form in order to validate a general method that will be used for further tests in a wider context. Full article
(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)
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Open AccessArticle Reliability and Degradation of Solar PV Modules—Case Study of 19-Year-Old Polycrystalline Modules in Ghana
Technologies 2017, 5(2), 22; doi:10.3390/technologies5020022
Received: 3 May 2017 / Accepted: 12 May 2017 / Published: 22 May 2017
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Abstract
Fourteen (14) rack-mounted polycrystalline modules installed on the concrete roof of the solar energy applications laboratory at the Kwame Nkrumah University of Science and Technology (KNUST) in Ghana, a hot humid environment, were assessed after 19 years of continuous outdoor exposure. The physical
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Fourteen (14) rack-mounted polycrystalline modules installed on the concrete roof of the solar energy applications laboratory at the Kwame Nkrumah University of Science and Technology (KNUST) in Ghana, a hot humid environment, were assessed after 19 years of continuous outdoor exposure. The physical state of the modules was documented using a visual inspection checklist. They were further assessed by current-voltage (I-V) characterization and thermal imaging. The modules were found to be in good physical state, except some bubbles on front side and minor discolouration/corrosion at edge of the cells. Compared with reference values, the performance decline of the modules observed over the exposure period was: nominal power (Pnom), 21% to 35%; short circuit current (Isc), 5.8% to 11.7%; open circuit voltage (Voc) 3.6% to 5.6% and 11.9% to 25.7% for fill factor (FF). It is hoped that this study will provide some helpful information to project developers, manufacturers and the research community on the long-term performance of PV modules in Ghana. Full article
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Open AccessArticle Effect of Heat Treatment on the Microstructure of Mg-4Al-Nd Alloys
Technologies 2017, 5(2), 23; doi:10.3390/technologies5020023
Received: 27 March 2017 / Revised: 17 May 2017 / Accepted: 18 May 2017 / Published: 23 May 2017
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Abstract
In the present work, Mg-4Al-xNd (x = 0, 1, 4 wt.%) alloys were prepared by a stir casting method, and the effect of the addition of Neodymium (Nd) as-cast and of heat-treated microstructures was studied. The addition of 1 wt.% Nd preferentially formed
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In the present work, Mg-4Al-xNd (x = 0, 1, 4 wt.%) alloys were prepared by a stir casting method, and the effect of the addition of Neodymium (Nd) as-cast and of heat-treated microstructures was studied. The addition of 1 wt.% Nd preferentially formed the Al2Nd phase and completely suppressed the formation of the intermetallic Mg17Al12 (γ) phase, which was initially present in the base alloy (Mg-4Al alloys). On increasing the Nd percentage from 1 to 4 wt.% in the base alloy, two intermetallic phases, Al2Nd and Al11Nd3, were observed in the microstructure, as higher levels of Nd led to a peritectic reaction between Al and the Al2Nd phase, and part of the Al2Nd transformed into the Al11Nd3 phase. The hardness of the as-cast alloy increased with the Nd content. Thus, the hardness increased from 57.1 ± 4.1 Hv of Mg-4Al to 66.5 ± 2.6 Hv of Mg-4Al-4Nd. It was also found that solutionizing and isothermal aging of alloys containing Nd at 180 °C for 96 h led to the size reduction of Al- and Nd-containing intermetallics without altering their morphologies. Further, it was found that Nd does not have any effect on the aging kinetics of the alloys because all of the alloys with and without Nd attained peak hardness at 24 h of aging time. Full article
(This article belongs to the Section Innovations in Materials Processing)
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Open AccessArticle Customised Alloy Blends for In-Situ Al339 Alloy Formation Using Anchorless Selective Laser Melting
Technologies 2017, 5(2), 24; doi:10.3390/technologies5020024
Received: 31 March 2017 / Revised: 18 May 2017 / Accepted: 19 May 2017 / Published: 24 May 2017
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Abstract
The additive manufacturing process Selective Laser Melting (SLM) can generate large thermal gradients during the processing of metallic powder; this can in turn lead to increased residual stress formation within a component. Metal anchors or support structures are required to be built during
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The additive manufacturing process Selective Laser Melting (SLM) can generate large thermal gradients during the processing of metallic powder; this can in turn lead to increased residual stress formation within a component. Metal anchors or support structures are required to be built during the process and forcibly hold SLM components to a substrate plate and minimise geometric distortion/warpage due to the process induced thermal residual stress. The requirement for support structures can limit the geometric freedom of the SLM process and increase post-processing operations. A novel method known as Anchorless Selective Laser Melting (ASLM) maintains processed material within a stress relieved state throughout the duration of a build. As a result, metal components formed using ASLM do not develop signification residual stresses within the process, thus, the conventional support structures or anchors used are not required to prevent geometric distortion. ASLM locally melts two or more compositionally distinct powdered materials that alloy under the action of the laser, forming into various combinations of hypo/hyper eutectic alloys with a new reduced solidification temperature. This new alloy is maintained in a semi-solid or stress reduced state for a prolonged period during the build with the assistance of elevated powder bed pre-heating. In this paper, custom blends of alloys are designed, manufactured and processed using ASLM. The purpose of this work is to create an Al339 alloy from compositionally distinct powder blends. The in-situ alloying of this material and ASLM processing conditions allowed components to be built in a stress-relieved state, enabling the manufacture of overhanging and unsupported features. Full article
(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)
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Open AccessArticle Testbed for Multilayer Conformal Additive Manufacturing
Technologies 2017, 5(2), 25; doi:10.3390/technologies5020025
Received: 8 April 2017 / Revised: 18 May 2017 / Accepted: 19 May 2017 / Published: 24 May 2017
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Abstract
Over the last two decades, additive manufacturing (AM) or 3D printing technologies have become pervasive in both the public and private sectors. Despite this growth, there has been little to no deviation from the fundamental approach of building parts using planar layers. This
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Over the last two decades, additive manufacturing (AM) or 3D printing technologies have become pervasive in both the public and private sectors. Despite this growth, there has been little to no deviation from the fundamental approach of building parts using planar layers. This undue reliance on a flat build surface limits part geometry and performance. To address these limitations, a new method of applying material onto or around existing surfaces with multilayer, thick features will be explored. Prior work proposes algorithms for defining conformal layers between existing and desired surfaces, however this work does not address the derivation of deposition paths, trajectories, or required hardware to achieve this new type of deposition. This paper presents (1) the derivation of deposition paths given a prescribed set of layers; (2) the design, characterization, and control of a proof-of-concept testbed; and (3) the derivation and application of time evolving trajectories subject to the material deposition constraints and mechanical constraints of the testbed. Derivations are presented in a general context with examples extending beyond the proposed testbed. Results show the feasibility of conformal material deposition (i.e., onto and around existing surfaces) with multilayer, thick features. Full article
(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)
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Open AccessArticle Application of an Emergency Alarm System for Physiological Sensors Utilizing Smart Devices
Technologies 2017, 5(2), 26; doi:10.3390/technologies5020026
Received: 12 April 2017 / Revised: 13 May 2017 / Accepted: 22 May 2017 / Published: 27 May 2017
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Abstract
Since innovative smart devices and body sensors including wearables have become prevalent with health informatics such as in Mobile Health (mHealth), we proposed to infer sensed data in sensor nodes to reduce the battery power consumption and bandwidth usage in wireless body area
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Since innovative smart devices and body sensors including wearables have become prevalent with health informatics such as in Mobile Health (mHealth), we proposed to infer sensed data in sensor nodes to reduce the battery power consumption and bandwidth usage in wireless body area networks. It is critical to raise an alarm when the user is in an urgent situation, which can be done by analysing the sensed data against the user’s activity status utilizing accelerometer sensors. However, when the activity changes frequently, there may be an increase in false alarms, which increases sensing and transferring of data, resulting in higher resource consumption. To reduce and mitigate the problem, we propose verifying the alarm and sending a user feedback using a smart device or smartwatch application so that a user can respond to whether the alarm is true or false. This paper presents a user-feedback system for use in activity recognition to mitigate and improve possible false alarm situations, which will consequently result in helping sensors to reduce the frequency of transactions and transmissions in wireless body area networks. As a contribution, the alarm determination can not only improve the accuracy of the alarm by utilising mobile app screen and speech recognition but can also reduce possible false alarms. It may also communicate with their physician in real-time who can assess the status with health data provided by the sensors. Full article
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Open AccessArticle Maxwell–Wagner Effect in Multi-Layered Dielectrics: Interfacial Charge Measurement and Modelling
Technologies 2017, 5(2), 27; doi:10.3390/technologies5020027
Received: 11 April 2017 / Revised: 12 May 2017 / Accepted: 25 May 2017 / Published: 29 May 2017
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Abstract
The development of high voltage direct current (HVDC) technologies generates new paradigms in research. In particular and contrary to the AC case, investigation of electrical conduction is not only needed for understanding the dielectric breakdown but also to describe the field distribution inside
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The development of high voltage direct current (HVDC) technologies generates new paradigms in research. In particular and contrary to the AC case, investigation of electrical conduction is not only needed for understanding the dielectric breakdown but also to describe the field distribution inside the insulation. Here, we revisit the so-called Maxwell–Wagner effect in multi-layered dielectrics by considering on the one hand a non-linear field dependent model of conductivity and on the other hand by performing space charge measurements giving access to the interfacial charge accumulated between different dielectrics. We show that space charge measurements give access to the amount of interfacial charge built-up by the Maxwell–Wagner effect between two dielectrics of different natures. Measurements also demonstrate that the field distribution undergoes a transition from a capacitive distribution to a resistive one, under long lasting stress. Full article
(This article belongs to the Section Innovations in Materials Processing)
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Open AccessArticle Synthesis and Sintering of ZnO Nanopowders
Technologies 2017, 5(2), 28; doi:10.3390/technologies5020028
Received: 14 April 2017 / Revised: 16 May 2017 / Accepted: 22 May 2017 / Published: 30 May 2017
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Abstract
Nanopowders are continuously under investigation as they open new perspectives in numerous fields. There are two main challenges to stimulating their development: sufficient low-cost, high throughput synthesis methods which lead to a production with well-defined and reproducible properties; and for ceramics specifically, the
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Nanopowders are continuously under investigation as they open new perspectives in numerous fields. There are two main challenges to stimulating their development: sufficient low-cost, high throughput synthesis methods which lead to a production with well-defined and reproducible properties; and for ceramics specifically, the conservation of the powders’ nanostructure after sintering. In this context, this paper presents the synthesis of a pure nanosized powder of ZnO (dv50~60 nm, easily redispersable) by using a continuous Segmented Flow Tubular Reactor (SFTR), which has previously shown its versatility and its robustness, ensuring a high powder quality and reproducibility over time. A higher scale of production can be achieved based on a “scale-out” concept by replicating the tubular reactors. The sinterability of ZnO nanopowders synthesized by the SFTR was studied, by natural sintering at 900 °C and 1100 °C, and Spark Plasma Sintering (SPS) at 900 °C. The performance of the synthesized nanopowder was compared to a commercial ZnO nanopowder of high quality. The samples obtained from the synthesized nanopowder could not be densified at low temperature by traditional sintering, whereas SPS led to a fully dense material after only 5 min at 900 °C, while also limiting the grain growth, thus leading to a nanostructured material. Full article
(This article belongs to the Special Issue Ceramic Technologies and Applications)
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Open AccessArticle Monitoring Approach to Evaluate the Performances of a New Deposition Nozzle Solution for DED Systems
Technologies 2017, 5(2), 29; doi:10.3390/technologies5020029
Received: 18 April 2017 / Revised: 19 May 2017 / Accepted: 25 May 2017 / Published: 31 May 2017
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Abstract
Abstract: In order to improve the process efficiency of a direct energy deposition (DED) system, closed loop control systems can be considered for monitoring the deposition and melting processes and adjusting the process parameters in real-time. In this paper, the monitoring of
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Abstract: In order to improve the process efficiency of a direct energy deposition (DED) system, closed loop control systems can be considered for monitoring the deposition and melting processes and adjusting the process parameters in real-time. In this paper, the monitoring of a new deposition nozzle solution for DED systems is approached through a simulation-experimental comparison. The shape of the powder flow at the exit of the nozzle outlet and the spread of the powder particles on the deposition plane are analyzed through 2D images of the powder flow obtained by monitoring the powder depositions with a high-speed camera. These experimental results are then compared with data obtained through a Computational Fluid Dynamics model. Preliminary tests are carried out by varying powder, carrier, and shielding mass flow, demonstrating that the last parameter has a significant influence on the powder distribution and powder flow geometry. Full article
(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)
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Open AccessArticle An Evaluation of an Educational Video Game on Mathematics Achievement in First Grade Students
Technologies 2017, 5(2), 30; doi:10.3390/technologies5020030
Received: 6 April 2017 / Revised: 26 May 2017 / Accepted: 30 May 2017 / Published: 1 June 2017
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Abstract
Development of early math skills is linked to future success in mathematics and other academics. Educational video games have been shown to promote academic achievement; however, few rigorous studies have evaluated the use of educational video games in supporting math development, especially in
[...] Read more.
Development of early math skills is linked to future success in mathematics and other academics. Educational video games have been shown to promote academic achievement; however, few rigorous studies have evaluated the use of educational video games in supporting math development, especially in early primary education. In the current study, an open-label randomized controlled trial was conducted involving 134 first grade students to determine, using standardized assessments, the impact of the educational mathematics tablet-based video game, Knowledge Battle, on math scores and self-competency. Overall, Knowledge Battle did improve math skills in participants who played the game. Among those with lower pre-game math skills, the Knowledge Battle group’s mean math score increased more than the control group’s mean math score (9.7 vs. 6.0; p = 0.02). There was no association between perceived sense of self-competency and total math score (p = 0.8141). However, players who had a higher sense of self-competency were more likely to enjoy playing the game. In conclusion, our findings suggest that Knowledge Battle was an acceptable and enjoyable educational mathematical video game for first grade students, and may be most impactful for those with low math skills. Full article
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Open AccessFeature PaperArticle Oxide Thin-Film Transistors on Fibers for Smart Textiles
Technologies 2017, 5(2), 31; doi:10.3390/technologies5020031
Received: 30 April 2017 / Revised: 26 May 2017 / Accepted: 29 May 2017 / Published: 2 June 2017
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Abstract
Smart textiles promise to have a significant impact on future wearable devices. Among the different approaches to combine electronic functionality and fabrics, the fabrication of active fibers results in the most unobtrusive integration and optimal compatibility between electronics and textile manufacturing equipment. The
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Smart textiles promise to have a significant impact on future wearable devices. Among the different approaches to combine electronic functionality and fabrics, the fabrication of active fibers results in the most unobtrusive integration and optimal compatibility between electronics and textile manufacturing equipment. The fabrication of electronic devices, in particular transistors on heavily curved, temperature sensitive, and rough textiles fibers is not easily achievable using standard clean room technologies. Hence, we evaluated different fabrication techniques and multiple fibers made from polymers, cotton, metal and glass exhibiting diameters down to 125 μm. The benchmarked techniques include the direct fabrication of thin-film structures using a low temperature shadow mask process, and the transfer of thin-film transistors (TFTs) fabricated on a thin (≈1 μm) flexible polymer membrane. Both approaches enable the fabrication of working devices, in particular the transfer method results in fully functional transistor fibers, with an on-off current ratio > 10 7 , a threshold voltage of ≈0.8 V , and a field effect mobility exceeding 7 c m 2 V 1 s 1 . Finally, the most promising fabrication approach is used to integrate a commercial nylon fiber functionalized with InGaZnO TFTs into a woven textile. Full article
(This article belongs to the Special Issue Wearable Technologies)
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Open AccessArticle Roll Bonding Properties of Al/Cu Bimetallic Laminates Fabricated by the Roll Bonding Technique
Technologies 2017, 5(2), 32; doi:10.3390/technologies5020032
Received: 1 May 2017 / Revised: 28 May 2017 / Accepted: 29 May 2017 / Published: 8 June 2017
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Abstract
Roll bonding (RB) of bimetal laminates is a solid phase method of bonding and has been widely used in the manufacturing of layered strips. This process is widely used for brazing sheet for automotive, aerospace, vessel, and electrical industries. In this study, 1-mm
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Roll bonding (RB) of bimetal laminates is a solid phase method of bonding and has been widely used in the manufacturing of layered strips. This process is widely used for brazing sheet for automotive, aerospace, vessel, and electrical industries. In this study, 1-mm bimetallic aluminum 1050 and pure copper (Al/Cu) laminates were produced using the roll bonding (RB) process. The RB process was carried out with thickness reduction ratios of 10%, 20%, and 30%, separately. Particular attention was focused on the bonding of the interface between Al and Cu layers. The optimization of thickness reduction ratios was obtained for the improvement of the bond strength of bimetallic laminates during the RB process. Also, the RB method was simulated using finite element simulation in ABAQUS software. Finite Element (FE) simulation was used to model the deformation of bimetallic laminates for various thickness reduction ratios, rolling temperatures, and tensile stresses. Particular attention was focused on the rolling pressure of Al and Cu layers in the simulation. The results show that the stress distribution in the bimetal Al/Cu laminates is an asymmetrical distribution. Moreover, the bonding strength of samples was obtained using the peeling test. Also, the fracture surface of roll bonded samples around the interface of laminates after the tensile test was studied to investigate the bonding quality by scanning electron microscopy (SEM). Full article
(This article belongs to the Section Innovations in Materials Processing)
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Open AccessArticle Random Walker Coverage Analysis for Information Dissemination in Wireless Sensor Networks
Technologies 2017, 5(2), 33; doi:10.3390/technologies5020033
Received: 4 May 2017 / Revised: 5 June 2017 / Accepted: 7 June 2017 / Published: 10 June 2017
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Abstract
The increasing technological progress in electronics provides network nodes with new and enhanced capabilities that allow the revisit of the traditional information dissemination (and collection) problem. The probabilistic nature of information dissemination using random walkers is exploited here to deal with challenges imposed
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The increasing technological progress in electronics provides network nodes with new and enhanced capabilities that allow the revisit of the traditional information dissemination (and collection) problem. The probabilistic nature of information dissemination using random walkers is exploited here to deal with challenges imposed by unconventional modern environments. In such systems, node operation is not deterministic (e.g., does not depend only on network nodes’ battery), but it rather depends on the particulars of the ambient environment (e.g., in the case of energy harvesting: sunshine, wind). The mechanism of information dissemination using one random walker is studied and analyzed in this paper under a different and novel perspective. In particular, it takes into account the stochastic nature of random walks, enabling further understanding of network coverage. A novel and original analysis is presented, which reveals the evolution network coverage by a random walker with respect to time. The derived analytical results reveal certain additional interesting aspects regarding network coverage, thus shedding more light on the random walker mechanism. Further analytical results, regarding the walker’s spatial movement and its associated neighborhood, are also confirmed through experimentation. Finally, simulation results considering random geometric graph topologies, which are suitable for modeling mobile environments, support and confirm the analytical findings. Full article
(This article belongs to the Section Environmental Technology)
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Open AccessArticle Vision-Based Robot Following Using PID Control
Technologies 2017, 5(2), 34; doi:10.3390/technologies5020034
Received: 15 February 2017 / Revised: 21 May 2017 / Accepted: 7 June 2017 / Published: 10 June 2017
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Abstract
Applications like robots which are employed for shopping, porter services, assistive robotics, etc., require a robot to continuously follow a human or another robot. This paper presents a mobile robot following another tele-operated mobile robot based on a PID (Proportional–Integral-Differential) controller. Here, we
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Applications like robots which are employed for shopping, porter services, assistive robotics, etc., require a robot to continuously follow a human or another robot. This paper presents a mobile robot following another tele-operated mobile robot based on a PID (Proportional–Integral-Differential) controller. Here, we use two differential wheel drive robots; one is a master robot and the other is a follower robot. The master robot is manually controlled and the follower robot is programmed to follow the master robot. For the master robot, a Bluetooth module receives the user’s command from an android application which is processed by the master robot’s controller, which is used to move the robot. The follower robot receives the image from the Kinect sensor mounted on it and recognizes the master robot. The follower robot identifies the x, y positions by employing the camera and the depth by using the Kinect depth sensor. By identifying the x, y, and z locations of the master robot, the follower robot finds the angle and distance between the master and follower robot, which is given as the error term of a PID controller. Using this, the follower robot follows the master robot. A PID controller is based on feedback and tries to minimize the error. Experiments are conducted for two indigenously developed robots; one depicting a humanoid and the other a small mobile robot. It was observed that the follower robot was easily able to follow the master robot using well-tuned PID parameters. Full article
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Open AccessArticle A Robust Multifunctional Sandwich Panel Design with Trabecular Structures by the Use of Additive Manufacturing Technology for a New De-Icing System
Technologies 2017, 5(2), 35; doi:10.3390/technologies5020035
Received: 29 January 2017 / Revised: 23 May 2017 / Accepted: 7 June 2017 / Published: 15 June 2017
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Abstract
Anti-ice systems assure a vital on-board function in most aircraft: ice prevention or de-icing is mandatory for all aerodynamic surfaces to preserve their performance, and for all the movable surfaces to allow the proper control of the plane. In this work, a novel
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Anti-ice systems assure a vital on-board function in most aircraft: ice prevention or de-icing is mandatory for all aerodynamic surfaces to preserve their performance, and for all the movable surfaces to allow the proper control of the plane. In this work, a novel multi-functional panel concept which integrates anti-icing directly inside the primary structure is presented. In fact, constructing the core of the sandwich with trabecular non-stochastic cells allows the presence of a heat exchanger directly inside the structure with a savings in weight and an improvement in thermal efficiency. This solution can be realized easily in a single-piece component using Additive Manufacturing (AM) technology without the need for joints, gluing, or welding. The objective of this study is to preliminarily investigate the mechanical properties of the core constructed with Selective Laser Melting (SLM); through the Design of Experiment (DOE), different design parameters were varied to understand how they affect the compression behaviour. Full article
(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)
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Open AccessArticle Open Source Multi-Head 3D Printer for Polymer-Metal Composite Component Manufacturing
Technologies 2017, 5(2), 36; doi:10.3390/technologies5020036
Received: 1 March 2017 / Revised: 5 April 2017 / Accepted: 18 April 2017 / Published: 15 June 2017
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Abstract
As low-cost desktop 3D printing is now dominated by free and open source self-replicating rapid prototype (RepRap) derivatives, there is an intense interest in extending the scope of potential applications to manufacturing. This study describes a manufacturing technology that enables a constrained set
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As low-cost desktop 3D printing is now dominated by free and open source self-replicating rapid prototype (RepRap) derivatives, there is an intense interest in extending the scope of potential applications to manufacturing. This study describes a manufacturing technology that enables a constrained set of polymer-metal composite components. This paper provides (1) free and open source hardware and (2) software for printing systems that achieves metal wire embedment into a polymer matrix 3D-printed part via a novel weaving and wrapping method using (3) OpenSCAD and parametric coding for customized g-code commands. Composite parts are evaluated from the technical viability of manufacturing and quality. The results show that utilizing a multi-polymer head system for multi-component manufacturing reduces manufacturing time and reduces the embodied energy of manufacturing. Finally, it is concluded that an open source software and hardware tool chain can provide low-cost industrial manufacturing of complex metal-polymer composite-based products. Full article
(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)
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Open AccessArticle A Novel Kernel-Based Regularization Technique for PET Image Reconstruction
Technologies 2017, 5(2), 37; doi:10.3390/technologies5020037
Received: 12 April 2017 / Revised: 11 June 2017 / Accepted: 16 June 2017 / Published: 19 June 2017
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Abstract
Positron emission tomography (PET) is an imaging technique that generates 3D detail of physiological processes at the cellular level. The technique requires a radioactive tracer, which decays and releases a positron that collides with an electron; consequently, annihilation photons are emitted, which can
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Positron emission tomography (PET) is an imaging technique that generates 3D detail of physiological processes at the cellular level. The technique requires a radioactive tracer, which decays and releases a positron that collides with an electron; consequently, annihilation photons are emitted, which can be measured. The purpose of PET is to use the measurement of photons to reconstruct the distribution of radioisotopes in the body. Currently, PET is undergoing a revamp, with advancements in data measurement instruments and the computing methods used to create the images. These computer methods are required to solve the inverse problem of “image reconstruction from projection”. This paper proposes a novel kernel-based regularization technique for maximum-likelihood expectation-maximization ( κ -MLEM) to reconstruct the image. Compared to standard MLEM, the proposed algorithm is more robust and is more effective in removing background noise, whilst preserving the edges; this suppresses image artifacts, such as out-of-focus slice blur. Full article
(This article belongs to the Special Issue Medical Imaging & Image Processing Ⅱ)
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Review

Jump to: Research

Open AccessReview Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need
Technologies 2017, 5(2), 15; doi:10.3390/technologies5020015
Received: 24 March 2017 / Revised: 7 April 2017 / Accepted: 10 April 2017 / Published: 12 April 2017
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Abstract
A useful and increasingly common additive manufacturing (AM) process is the selective laser melting (SLM) or direct metal laser sintering (DMLS) process. SLM/DMLS can produce full-density metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing.
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A useful and increasingly common additive manufacturing (AM) process is the selective laser melting (SLM) or direct metal laser sintering (DMLS) process. SLM/DMLS can produce full-density metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing. This limits the usefulness and applicability of the process, particularly in the fabrication of parts with delicate overhanging and protruding features. The purpose of this study was to examine the current insight and progress made toward understanding and eliminating the problem in overhanging and protruding structures. To accomplish this, a survey of the literature was undertaken, focusing on process modeling (general, heat transfer, stress and distortion and material models), direct process control (input and environmental control, hardware-in-the-loop monitoring, parameter optimization and post-processing), experiment development (methods for evaluation, optical and mechanical process monitoring, imaging and design-of-experiments), support structure optimization and overhang feature design; approximately 143 published works were examined. The major findings of this study were that a small minority of the literature on SLM/DMLS deals explicitly with the overhanging stress problem, but some fundamental work has been done on the problem. Implications, needs and potential future research directions are discussed in-depth in light of the present review. Full article
(This article belongs to the Special Issue Additive Manufacturing Technologies and Applications)
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Open AccessReview Review of Computational Methods on Brain Symmetric and Asymmetric Analysis from Neuroimaging Techniques
Technologies 2017, 5(2), 16; doi:10.3390/technologies5020016
Received: 26 November 2016 / Revised: 16 April 2017 / Accepted: 17 April 2017 / Published: 18 April 2017
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Abstract
The brain is the most complex organ in the human body and it is divided into two hemispheres—left and right. The left hemisphere is responsible for control of the right side of our body, whereas the right hemisphere is responsible for control of
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The brain is the most complex organ in the human body and it is divided into two hemispheres—left and right. The left hemisphere is responsible for control of the right side of our body, whereas the right hemisphere is responsible for control of the left side of our body. Brain image segmentation from different neuroimaging modalities is one of the important parts of clinical diagnostic tools. Neuroimaging based digital imagery generally contain noise, inhomogeneity, aliasing artifacts, and orientational deviations. Therefore, accurate segmentation of brain images is a very difficult task. However, the development of accurate segmentation of brain images is very important and crucial for a correct diagnosis of any brain related diseases. One of the fundamental segmentation tasks is to identify and segment inter-hemispheric fissure/mid-sagittal planes, which separate the two hemispheres of the brain. Moreover, the symmetric/asymmetric analyses of left and right hemispheres of brain structures are important for radiologists to analyze diseases such as Alzheimer’s, autism, schizophrenia, lesions and epilepsy. Therefore, in this paper, we have analyzed the existing computational techniques used to find brain symmetric/asymmetric analysis in different neuroimaging techniques such as the magnetic resonance (MR), computed tomography (CT), positron emission tomography (PET), single-photon emission computed tomography (SPECT), which are utilized for detecting various brain related disorders. Full article
(This article belongs to the Special Issue Medical Imaging & Image Processing Ⅱ)
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Open AccessReview Cuff-Less and Continuous Blood Pressure Monitoring: A Methodological Review
Technologies 2017, 5(2), 21; doi:10.3390/technologies5020021
Received: 5 March 2017 / Revised: 27 April 2017 / Accepted: 5 May 2017 / Published: 9 May 2017
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Abstract
Blood pressure (BP) is one of the most important monitoring parameters in clinical medicine. For years, the cuff-based sphygmomanometer and the arterial invasive line have been the gold standards for care professionals to assess BP. During the past few decades, the wide spread
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Blood pressure (BP) is one of the most important monitoring parameters in clinical medicine. For years, the cuff-based sphygmomanometer and the arterial invasive line have been the gold standards for care professionals to assess BP. During the past few decades, the wide spread of the oscillometry-based BP arm or wrist cuffs have made home-based BP assessment more convenient and accessible. However, the discontinuous nature, the inability to interface with mobile applications, the relative inaccuracy with movement, and the need for calibration have rendered those BP oscillometry devices inadequate for next-generation healthcare infrastructure where integration and continuous data acquisition and communication are required. Recently, the indirect approach to obtain BP values has been intensively investigated, where BP is mathematically derived through the “Time Delay” in propagation of pressure waves in the vascular system. This holds promise for the realization of cuffless and continuous BP monitoring systems, for both patients and healthy populations in both inpatient and outpatient settings. This review highlights recent efforts in developing these next-generation blood pressure monitoring devices and compares various mathematical models. The unmet challenges and further developments that are crucial to develop “Time Delay”-based BP devices are also discussed. Full article
(This article belongs to the Special Issue Wearable Technologies)
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