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Inventions, Volume 3, Issue 3 (September 2018)

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Open AccessArticle Cyber Physical Energy Systems Modules for Power Sharing Controllers in Inverter Based Microgrids
Received: 25 July 2018 / Revised: 25 August 2018 / Accepted: 8 September 2018 / Published: 11 September 2018
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Abstract
The Microgrids (MGs) are an effective way to deal with the smart grid challenges, including service continuity in the event of a grid interruption, and renewable energy integration. The MGs are compounded by multiple distributed generators (DGs), and the main control goals are
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The Microgrids (MGs) are an effective way to deal with the smart grid challenges, including service continuity in the event of a grid interruption, and renewable energy integration. The MGs are compounded by multiple distributed generators (DGs), and the main control goals are load demand sharing and voltage and frequency stability. Important research has been reported to cope with the implementation challenges of the MGs including the power sharing control problem, where the use of cybernetic components such as virtual components, and communication systems is a common characteristic. The use of these cybernetic components to control complex physical systems generates new modeling challenges in order to achieve an adequate balance between complexity and accuracy in the MG model. The standardization problem of the cyber-physical MG models is addressed in this work, using a cyber-physical energy systems (CPES) modeling methodology to build integrated modules, and define the communication architectures that each power sharing control strategy requires in an AC-MG. Based on these modules, the control designer can identify the signals and components that eventually require a time delay analysis, communication requirements evaluation, and cyber-attacks’ prevention strategies. Similarly, the modules of each strategy allow for analyzing the potential advantages and drawbacks of each power sharing control technique from a cyber physical perspective. Full article
(This article belongs to the Special Issue Microgrids 2018)
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Open AccessReview PDMS-Based Microfluidic Devices for Cell Culture
Received: 26 July 2018 / Revised: 1 September 2018 / Accepted: 4 September 2018 / Published: 6 September 2018
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Abstract
Microfluidic technology has affirmed itself as a powerful tool in medical and biological research by offering the possibility of managing biological samples in tiny channels and chambers. Among the different applications, the use of microfluidics for cell cultures has attracted much interest from
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Microfluidic technology has affirmed itself as a powerful tool in medical and biological research by offering the possibility of managing biological samples in tiny channels and chambers. Among the different applications, the use of microfluidics for cell cultures has attracted much interest from scientists worldwide. Traditional cell culture methods need high quantities of samples and reagents that are strongly reduced in miniaturized systems. In addition, the microenvironment is better controlled by scaling down. In this paper, we provide an overview of the aspects related to the design of a novel microfluidic culture chamber, the fabrication approach based on polydimethylsiloxane (PDMS) soft-lithography, and the most critical issues in shrinking the size of the system. Full article
(This article belongs to the Special Issue Microfluidics and Nanofluidics)
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Open AccessArticle Belt-Driven Open Source Circuit Mill Using Low-Cost 3-D Printer Components
Received: 13 August 2018 / Revised: 28 August 2018 / Accepted: 30 August 2018 / Published: 5 September 2018
Cited by 1 | Viewed by 623 | PDF Full-text (7986 KB) | HTML Full-text | XML Full-text
Abstract
Barriers to inventing electronic devices involve challenges of iterating electronic designs due to long lead times for professional circuit board milling or high costs of commercial milling machines. To overcome these barriers, this study provides open source (OS) designs for a low-cost circuit
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Barriers to inventing electronic devices involve challenges of iterating electronic designs due to long lead times for professional circuit board milling or high costs of commercial milling machines. To overcome these barriers, this study provides open source (OS) designs for a low-cost circuit milling machine. First, design modifications for mechanical and electrical subsystems of the OS Distributed 3-D (D3D) Robotics prototyping system are provided. Next, Copper Carve, an OS custom graphical user interface, is developed to enable circuit board milling by implementing backlash and substrate distortion compensation. The performance of the OS D3D circuit mill is then quantified and validated for: positional accuracy, cut quality, feature accuracy, and distortion compensation. Finally, the return on investment is calculated for inventors using it. The results show by properly compensating for motion inaccuracies with Copper Carve, the machine achieves a motion resolution of 10 microns, which is more than adequate for most circuit designs. The mill is at least five times less expensive than all commercial alternatives and the material costs of the D3D mill are repaid from fabricating 20–43 boards. The results show that the OS circuit mill is of high-enough quality to enable rapid invention and distributed manufacturing of complex products containing custom electronics. Full article
(This article belongs to the Special Issue Innovations in 3-D Printing)
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Open AccessArticle A Soft-Switched DC/DC Converter Using Integrated Dual Half-Bridge with High Voltage Gain and Low Voltage Stress for DC Microgrid Applications
Received: 26 July 2018 / Revised: 22 August 2018 / Accepted: 29 August 2018 / Published: 3 September 2018
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Abstract
In this paper, a soft-switched boost converter including an integrated dual half-bridge circuit with high voltage gain and continuous input current is introduced that can be suitable for the applications requiring a wide voltage gain range, such as for the front-end of the
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In this paper, a soft-switched boost converter including an integrated dual half-bridge circuit with high voltage gain and continuous input current is introduced that can be suitable for the applications requiring a wide voltage gain range, such as for the front-end of the inverter in a DC microgrid to integrate renewable energy sources (RES). In the proposed converter, two half-bridge converters are connected in series at the output stage to enhance the voltage gain. Additionally, the balanced voltage multiplier stage is employed at the output to increase the voltage conversion ratio, as well as distribute the voltage stress across semiconductors; hence, switches with smaller on-resistance RDS(on) can be adopted resulting in an improvement in the efficiency. The converter takes advantage of the clamp circuit not only to confine the voltage stress of switches, but also to achieve the soft-switching, which leads to a reduction in the switching loss as well as the cost. The mentioned features make the proposed converter a proper choice for interfacing RES to the DC-link bus of the inverter. The operation modes, steady-state analysis, and design consideration of the proposed topology have been demonstrated in the paper. A 1-kW laboratory prototype was built using gallium nitride (GaN) transistors and silicon carbide (SiC) diodes to confirm the effectiveness of the proposed topology. Full article
(This article belongs to the Special Issue Emerging Technologies Enabling Smart Grid)
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Open AccessArticle Protection of Service-Oriented Environments Serving Critical Infrastructures
Received: 26 July 2018 / Revised: 20 August 2018 / Accepted: 23 August 2018 / Published: 30 August 2018
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Abstract
The emergence of service-oriented architectures has driven the shift towards a service-oriented paradigm, which has been adopted in several application domains. The advent of cloud computing facilities and recently of edge computing environments has increased the aforementioned paradigm shift towards service provisioning. In
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The emergence of service-oriented architectures has driven the shift towards a service-oriented paradigm, which has been adopted in several application domains. The advent of cloud computing facilities and recently of edge computing environments has increased the aforementioned paradigm shift towards service provisioning. In this context, various “traditional” critical infrastructure components have turned to services, being deployed and managed on top of cloud and edge computing infrastructures. However, the latter poses a specific challenge: the services of the critical infrastructures within and across application verticals/domains (e.g., transportation, health, industrial venues, etc.) need to be continuously available with near-zero downtime. In this context, this paper presents an approach for high-performance monitoring and failure detection of critical infrastructure services that are deployed in virtualized environments. The failure detection framework consists of distributed agents (i.e., monitoring services) to ensure timely collection of monitoring data, while it is enhanced with a voting algorithm to minimize the case of false positives. The goal of the proposed approach is to detect failures in datacenters that support critical infrastructures by targeting both the acquisition of monitoring data in a performant way and the minimization of false positives in terms of potential failure detection. The specific approach is the baseline towards decision making and triggering of actions in runtime to ensure service high availability, given that it provides the required data for decision making on time with high accuracy. Full article
(This article belongs to the Special Issue Innovation in Machine Intelligence for Critical Infrastructures)
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Open AccessArticle A New Three-Level Flying-Capacitor Boost Converter with an Integrated LC2D Output Network for Fuel-Cell Vehicles: Analysis and Design
Received: 21 July 2018 / Revised: 20 August 2018 / Accepted: 22 August 2018 / Published: 28 August 2018
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Abstract
In this paper, a new three-level boost converter with continuous input current, common ground, reduced voltage stress on the power switches, and wide voltage gain range is proposed. The proposed converter is composed of a three-level flying-capacitor switching cell and an integrated LC
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In this paper, a new three-level boost converter with continuous input current, common ground, reduced voltage stress on the power switches, and wide voltage gain range is proposed. The proposed converter is composed of a three-level flying-capacitor switching cell and an integrated LC2D output network. The LC2D output network enhances the voltage gain of the converter and reduces the voltage stress on the power switches. The proposed converter is a good candidate to interface fuel cells to the dc-link bus of the three-phase inverter of an electric vehicle (EV). A full steady-state analysis of the proposed converter in the continuous conduction mode (CCM) is given in this paper. A 1.2 kW scaled-down laboratory setup was built using gallium nitride (GaN) transistors and silicon carbide (SiC) diodes to verify the feasibility of the proposed converter. Full article
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Open AccessReview A Review of Current Methods in Microfluidic Device Fabrication and Future Commercialization Prospects
Received: 30 June 2018 / Revised: 15 August 2018 / Accepted: 20 August 2018 / Published: 28 August 2018
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Abstract
Microfluidic devices currently play an important role in many biological, chemical, and engineering applications, and there are many ways to fabricate the necessary channel and feature dimensions. In this review, we provide an overview of microfabrication techniques that are relevant to both research
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Microfluidic devices currently play an important role in many biological, chemical, and engineering applications, and there are many ways to fabricate the necessary channel and feature dimensions. In this review, we provide an overview of microfabrication techniques that are relevant to both research and commercial use. A special emphasis on both the most practical and the recently developed methods for microfluidic device fabrication is applied, and it leads us to specifically address laminate, molding, 3D printing, and high resolution nanofabrication techniques. The methods are compared for their relative costs and benefits, with special attention paid to the commercialization prospects of the various technologies. Full article
(This article belongs to the Special Issue Microfluidics and Nanofluidics)
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Open AccessArticle Experimental Investigation of Impact Localization in Composite Plate Using Newly Developed Imaging Method
Received: 3 August 2018 / Revised: 21 August 2018 / Accepted: 22 August 2018 / Published: 27 August 2018
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Abstract
This paper focuses on impact localization of composite structures, which possess more complexity in the guided wave propagation due to the anisotropic behavior of composite materials. In this work, a composite plate was manufactured by using a compression molding process with proper pressure
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This paper focuses on impact localization of composite structures, which possess more complexity in the guided wave propagation due to the anisotropic behavior of composite materials. In this work, a composite plate was manufactured by using a compression molding process with proper pressure and temperature cycle. Eight layers of woven composite prepreg were used to manufacture the composite plate. A structural health monitoring (SHM) technique was implemented with piezoelectric wafer active sensors (PWAS) to detect and localize the impact on the plate. There were two types of impact event that were considered in this paper (a) low energy impact event (b) high energy impact event. Two clusters of sensors recorded the guided acoustic waves generated from the impact. The acoustic signals were then analyzed using a wavelet transform based time-frequency analysis. The proposed SHM technique successfully detected and localized the impact event on the plate. The experimentally measured impact locations were compared with the actual impact locations. An immersion ultrasonic scanning method was used to visualize the composite plate before and after the impact event. A high frequency 10 MHz 1-inch focused transducer was used to scan the plate in the immersion tank. Scanning results showed that there was no visible manufacturing damage in the composite plate. However, clear impact damage was observed after the high-energy impact event. Full article
(This article belongs to the Special Issue Structural Health Monitoring and Their Applications Across Industry)
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Open AccessArticle Gorilla: An Open Interface for Smart Agents and Real-Time Power Microgrid System Simulations
Received: 1 July 2018 / Revised: 3 August 2018 / Accepted: 20 August 2018 / Published: 27 August 2018
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Abstract
A recurring issue when studying agent-based algorithms and strategies for Power Microgrid Systems is having to construct an interface between the agent domain and the electrical model domain being simulated. Many different tools exist for such simulations, each with its own special external
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A recurring issue when studying agent-based algorithms and strategies for Power Microgrid Systems is having to construct an interface between the agent domain and the electrical model domain being simulated. Many different tools exist for such simulations, each with its own special external interface. Although many interfacing efforts have been published before, many of them support only special cases, while others are too complex and require a long learning curve to be used for even simple scenarios. This work presents a simple programming application interface (API) that aims to provide programming access to the electrical system model for any real-time simulation tool, from any agent-based platform, or programming language. The simplicity of the interface stems from the assumption that the simulation happens in real-time and the agent domain is not being simulated. We propose four basic operations for the API: read, write, call, and subscribe/call-back. We tested these by supporting two examples. In one of the examples, we present a creative way to have the model access libraries that are not available in the simulated environment. Full article
(This article belongs to the Special Issue Microgrids 2018)
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Open AccessArticle Gene Delivery System Using Droplet Injector and Temperature-Controlled Planarian Holder
Received: 26 July 2018 / Revised: 15 August 2018 / Accepted: 16 August 2018 / Published: 21 August 2018
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Abstract
A microinjection system for gene delivery to a planarian was presented with materials widely used by manufacturers. The system consists of a nanoliter droplet generator/injector and a planarian holder. Glass capillary needles were used to consistently generate droplets and to inject droplets into
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A microinjection system for gene delivery to a planarian was presented with materials widely used by manufacturers. The system consists of a nanoliter droplet generator/injector and a planarian holder. Glass capillary needles were used to consistently generate droplets and to inject droplets into a planarian. The holder provides a low-temperature environment that immobilizes the planarian for injection. Our system was tested and showed successful injections of microbeads and droplets with double-stranded RNA into the planarian. The results demonstrated the capability of our system as an alternative for gene delivery for studying gene functions in planarians or other living objects for regenerative medicine studies. Full article
(This article belongs to the Special Issue Microfluidics and Nanofluidics)
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Open AccessArticle Low-Level Control of 3D Printers from the Cloud: A Step toward 3D Printer Control as a Service
Received: 13 July 2018 / Revised: 9 August 2018 / Accepted: 17 August 2018 / Published: 19 August 2018
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Abstract
Control as a Service (CaaS) is an emerging paradigm where low-level control of a device is moved from a local controller to the Cloud, and provided to the device as an on-demand service. Among its many benefits, CaaS gives the device access to
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Control as a Service (CaaS) is an emerging paradigm where low-level control of a device is moved from a local controller to the Cloud, and provided to the device as an on-demand service. Among its many benefits, CaaS gives the device access to advanced control algorithms which may not be executable on a local controller due to computational limitations. As a step toward 3D printer CaaS, this paper demonstrates the control of a 3D printer by streaming low-level stepper motor commands (as opposed to high-level G-codes) directly from the Cloud to the printer. The printer is located at the University of Michigan, Ann Arbor, while its stepper motor commands are calculated using an advanced motion control algorithm running on Google Cloud computers in South Carolina and Australia. The stepper motor commands are sent over the internet using the user datagram protocol (UDP) and buffered to mitigate transmission delays; checks are included to ensure accuracy and completeness of the transmitted data. All but one part printed using the cloud-based controller in both locations were hitch free (i.e., no pauses due to excessive transmission delays). Moreover, using the cloud-based controller, the parts printed up to 54% faster than using a standard local controller, without loss of accuracy. Full article
(This article belongs to the Special Issue Innovations in 3-D Printing)
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Open AccessArticle Design of a Hybrid AC/DC Microgrid Using HOMER Pro: Case Study on an Islanded Residential Application
Received: 26 June 2018 / Revised: 20 July 2018 / Accepted: 10 August 2018 / Published: 14 August 2018
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Abstract
This paper is concerned with the design of an autonomous hybrid alternating current/direct current (AC/DC) microgrid for a community system, located on an island without the possibility of grid connection. It is comprised of photovoltaic (PV) arrays and a diesel generator, AC loads,
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This paper is concerned with the design of an autonomous hybrid alternating current/direct current (AC/DC) microgrid for a community system, located on an island without the possibility of grid connection. It is comprised of photovoltaic (PV) arrays and a diesel generator, AC loads, and battery energy storage devices for ensuring uninterruptible power supply during prolonged periods of low sunshine. A multi-objective, non-derivative optimisation is considered in this residential application; the primary objective is the system cost minimisation, while it is also required that no load shedding is allowed. Additionally, the CO2 emissions are calculated to demonstrate the environmental benefit the proposed system offers. The commercial software, HOMER Pro, is utilised to identify the least-cost design among hundreds of options and simultaneously satisfy the secondary objective. A sensitivity analysis is also performed to evaluate design robustness against the uncertainty pertaining to fuel prices and PV generation. Finally, an assessment of the capabilities of the utilised optimisation platform is conducted, and a theoretical discussion sheds some light on the proposal for an enhanced design tool addressing the identified issues. Full article
(This article belongs to the Special Issue Microgrids 2018)
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Open AccessArticle Examining the Effect of Flow Rate Ratio on Droplet Generation and Regime Transition in a Microfluidic T-Junction at Constant Capillary Numbers
Received: 16 July 2018 / Revised: 7 August 2018 / Accepted: 8 August 2018 / Published: 10 August 2018
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Abstract
The focus of this work is to examine the effect of flow rate ratio (quotient of the dispersed phase flow rate over the continuous phase flow rate) on a regime transition from squeezing to dripping at constant capillary numbers. The effect of the
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The focus of this work is to examine the effect of flow rate ratio (quotient of the dispersed phase flow rate over the continuous phase flow rate) on a regime transition from squeezing to dripping at constant capillary numbers. The effect of the flow rate ratio on the volume of droplets generated in a microfluidic T-junction is discussed, and a new scaling law to estimate their volume is proposed. Existing work on a regime transition reported by several researchers focuses on the effect of the capillary number on regime transition, and the results that are presented in this paper advance the current understanding by indicating that the flow rate ratio is another parameter that dictates regime transition. In this paper, the transition between squeezing and dripping regimes is reported at constant capillary numbers, with a transition region identified between squeezing and dripping regimes. Dripping is observed at lower flow rate ratios and squeezing at higher flow rate ratios, with a transition region between the two regimes at flow rate ratios between 1 and 2. This is presented in a flow regime map that is constructed based on the observed mechanism. A scaling model is proposed to characterise droplet volume in terms of flow rate ratio and capillary number. The effect of flow rate ratio on the non-dimensional droplet volume is presented, and lastly, the droplet volume is expressed in terms of a range of parameters, such as the viscosity ratio between the dispersed and the continuous phase, capillary number, and the geometrical characteristics of the channels. Full article
(This article belongs to the Special Issue Microfluidics and Nanofluidics)
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Open AccessArticle Nonlinear Vibrations of Innovative One-Way Clutch in Vehicle Alternator
Received: 27 May 2018 / Revised: 24 July 2018 / Accepted: 26 July 2018 / Published: 30 July 2018
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Abstract
One-way clutches have been proposed for vehicle alternators. The clutch can play an important role in reducing vibrations of the vehicle engine accessory system, but the severe vibrations of the clutch subsystem limit its stability and durability. This paper investigates the nonlinear vibrations
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One-way clutches have been proposed for vehicle alternators. The clutch can play an important role in reducing vibrations of the vehicle engine accessory system, but the severe vibrations of the clutch subsystem limit its stability and durability. This paper investigates the nonlinear vibrations of a one-way clutch between the accessory pulley and the alternator shaft. The one-way clutch is modelled as a discontinuous stiffness system, and the simplified model is analyzed using discontinuous transform to determine the periodic, primary resonance and the sub and super harmonic resonance solutions. The typical system model is numerically solved and the spectrum and phase plots are characterized. The results give a big picture of and insights into the nonlinear vibration features of one-way clutch system. A relevant US patent is pending. Full article
(This article belongs to the Special Issue Structural Health Monitoring and Their Applications Across Industry)
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Open AccessArticle Biocompatibility of 3D-Printed Methacrylate for Hearing Devices
Received: 17 July 2018 / Revised: 23 July 2018 / Accepted: 24 July 2018 / Published: 27 July 2018
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Abstract
The capacity of 3D printing (3DP) technologies to initiate speedy polymerization of solvent-free resins accounts for their utility in the manufacturing of medical devices. Nonetheless, independent biological evaluation of 3D-printed materials is recommended due to the unique parameters of the manufacturing process, which
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The capacity of 3D printing (3DP) technologies to initiate speedy polymerization of solvent-free resins accounts for their utility in the manufacturing of medical devices. Nonetheless, independent biological evaluation of 3D-printed materials is recommended due to the unique parameters of the manufacturing process, which can influence their physical, chemical and biological properties. In this study, E-Shell 450 clear methacrylate indicated for 3DP of hearing devices was examined for biological safety using zebrafish bioassays adapted to Organization for Economic Cooperation and Development (OECD) fish embryo test. In addition, the proprietary material was characterized for composition using headspace gas chromatography–mass spectrometry (GC–MS). To initiate the biological test, newly fertilized zebrafish eggs were cultured on non-treated and ethanol-treated methacrylates in glass petri dishes with ultrapure water, incubated at 28.5 °C and assessed for developmental endpoints of toxicity at 24 h intervals until 96 h. Toxicological data indicate that non-treated methacrylate is extremely toxic in zebrafish bioassays, whereas ethanol-treated counterpart showed a relative lower toxicity possibly due to ethanoic–aqueous interactions as observed by GC–MS. With the current influx of 3D printing materials, users are urged to exercise caution. Operators must also take cognizance of the potential toxicity of the chemicals used in 3DP and implement safety measures to limit their exposure. Full article
(This article belongs to the Special Issue Innovations in 3-D Printing)
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Open AccessArticle Direct Assessment of Alcohol Consumption in Mental State Using Brain Computer Interfaces and Grammatical Evolution
Received: 17 July 2018 / Accepted: 25 July 2018 / Published: 27 July 2018
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Abstract
Alcohol consumption affects the function of the brain and long-term excessive alcohol intake can lead to severe brain disorders. Wearable electroencephalogram (EEG) recording devices combined with Brain Computer Interface (BCI) software may serve as a tool for alcohol-related brain wave assessment. In this
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Alcohol consumption affects the function of the brain and long-term excessive alcohol intake can lead to severe brain disorders. Wearable electroencephalogram (EEG) recording devices combined with Brain Computer Interface (BCI) software may serve as a tool for alcohol-related brain wave assessment. In this paper, a method for mental state assessment from alcohol-related EEG recordings is proposed. EEG recordings are acquired with the Emotiv EPOC+, after consumption of three separate doses of alcohol. Data from the four stages (alcohol-free and three levels of doses) are processed using the OpenViBE platform. Spectral and statistical features are calculated, and Grammatical Evolution is employed for discrimination across four classes. Obtained results in terms of accuracy reached high levels (89.95%), which renders the proposed approach suitable for direct assessment of the driver’s mental state for road safety and accident avoidance in a potential in-vehicle smart system. Full article
(This article belongs to the Special Issue Frontiers in Wearable Devices)
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Open AccessArticle Heat Transfer Enhancement by Detached S-Ribs for Twin-Pass Parallelogram Channel
Received: 29 May 2018 / Revised: 10 July 2018 / Accepted: 11 July 2018 / Published: 23 July 2018
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Abstract
Detached S-ribs are proposed to arrange in the stagger manner along two parallelogram straight channels interconnecting with a 180° smooth-walled sharp bend for heat transfer enhancements. The detailed Nusselt number distributions over the two opposite channel endwalls at Reynolds numbers of 5000, 7500,
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Detached S-ribs are proposed to arrange in the stagger manner along two parallelogram straight channels interconnecting with a 180° smooth-walled sharp bend for heat transfer enhancements. The detailed Nusselt number distributions over the two opposite channel endwalls at Reynolds numbers of 5000, 7500, 10,000, 12,500, 15,000 and 20,000 are measured using the steady-state infrared thermography method. The accompanying Fanning friction factors are evaluated from the measured pressure drops across the entire test channel. Having acquired the averaged heat transfer properties and Fanning friction factors, the thermal performance factors are determined under the criterion of constant pumping power consumptions. With the regional accelerated flows between the detached S-ribs and the channel endwall, the considerable heat transfer elevations from the Dittus–Boelter correlation levels are achieved. The comparative thermal performances between the two similar twin-pass parallelogram channels with detached 90° and S-ribs disclose the higher regional heat transfer rates over the turning region and the larger Fanning frictions factors, leading to the lower thermal performance factors, for present test channel with the detached S-ribs. To assist design applications, two sets of empirical correlations evaluating the regionally averaged Nusselt numbers and Fanning friction factors are devised for present twin-pass parallelogram channel with the detached S-ribs. Full article
(This article belongs to the Special Issue Heat Transfer and Its Innovative Applications)
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Open AccessArticle Cyclic Block Copolymer Microchannel Fabrication and Sealing for Microfluidics Applications
Received: 16 May 2018 / Revised: 3 July 2018 / Accepted: 13 July 2018 / Published: 16 July 2018
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High mechanical rigidity, chemical resistance, and ultraviolet-visible light transmissivity of thermoplastics are attractive characteristics in microfluidics because various biomedical microfluidic devices require solvent, acid, or base manipulation, and optical observation or detection. The cyclic block copolymer (CBC) is a new class of thermoplastics
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High mechanical rigidity, chemical resistance, and ultraviolet-visible light transmissivity of thermoplastics are attractive characteristics in microfluidics because various biomedical microfluidic devices require solvent, acid, or base manipulation, and optical observation or detection. The cyclic block copolymer (CBC) is a new class of thermoplastics with excellent optical properties, low water absorption, favorable chemical resistance, and low density, which make it ideal for use in polymer microfluidic applications. In the polymer microfabrication process, front-end microchannel fabrication and post-end bonding are critical steps that determine the success of polymer microfluidic devices. In this study, for the first time, we verified the performance of CBC created through front-end microchannel fabrication by applying hot embossing and post-end sealing and bonding, and using thermal fusion and ultraviolet (UV)/ozone surface-assist bonding methods. Two grades of CBC were evaluated and compared with two commonly used cyclic olefin polymers, cyclic olefin copolymers (COC), and cyclic olefin polymers (COP). The results indicated that CBCs provided favorable pattern transfer (>99%) efficiency and high bonding strength in microchannel fabrication and bonding procedures, which is ideal for use in microfluidics. Full article
(This article belongs to the Special Issue Microfluidics and Nanofluidics)
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Open AccessReview A Survey on the Affordances of “Hearables”
Received: 29 May 2018 / Revised: 9 July 2018 / Accepted: 10 July 2018 / Published: 14 July 2018
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Abstract
Recent developments pertaining to ear-mounted wearable computer interfaces (i.e., “hearables”) offer a number of distinct affordances over other wearable devices in ambient and ubiquitous computing systems. This paper provides a survey of hearables and the possibilities that they offer as computer interfaces. Thereafter,
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Recent developments pertaining to ear-mounted wearable computer interfaces (i.e., “hearables”) offer a number of distinct affordances over other wearable devices in ambient and ubiquitous computing systems. This paper provides a survey of hearables and the possibilities that they offer as computer interfaces. Thereafter, these affordances are examined with respect to other wearable interfaces. Finally, several historical trends are noted within this domain, and multiple paths for future development are offered. Full article
(This article belongs to the Special Issue Frontiers in Wearable Devices)
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Open AccessArticle An Improved Control Strategy for Three-Phase Power Inverters in Islanded AC Microgrids
Received: 7 June 2018 / Revised: 2 July 2018 / Accepted: 10 July 2018 / Published: 11 July 2018
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Abstract
Microgrids (MGs) are composed of multiple distributed generators (DGs) interfaced to micronetwork through paralleled connected power inverters (PIs). Load sharing among multiple DG units is an important task for autonomous operation of microgrids. In order to realize satisfactory power sharing and voltage regulation
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Microgrids (MGs) are composed of multiple distributed generators (DGs) interfaced to micronetwork through paralleled connected power inverters (PIs). Load sharing among multiple DG units is an important task for autonomous operation of microgrids. In order to realize satisfactory power sharing and voltage regulation between DG units, different voltage droop control strategies have been reported in the literature. In the medium voltage (MV) microgrids, power sharing, and voltage regulation often deteriorate due to dependence on nontrivial feeder impedances. The conventional control strategies are subject to steady-state active and reactive power-sharing errors along with system voltage and frequency deviations. Furthermore, complex microgrid configurations either in looped or meshed networks often make power balancing and voltage regulations more challenging. This paper presents an improved control strategy that can be extended for radial networks in order to enhance the accuracy of power sharing and voltage regulation. The proposed control strategy considers load voltage magnitude regulation as opposed the voltage regulation at inverters terminals. At the same time, a supervisory control loop is added to observe and correct system frequency deviations. This proposed method is aimed at replacing paralleled inverter control methods hitherto used. Simulation studies of the proposed scheme in comparison with the conventional control strategy in MATLAB/Simulink validate the effectiveness of the proposed strategy. Full article
(This article belongs to the Special Issue Microgrids 2018)
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Open AccessArticle Adjustment and Measurement of Contact Angle with Electrowetting on a Quartz-Crystal Microbalance
Received: 4 June 2018 / Revised: 26 June 2018 / Accepted: 26 June 2018 / Published: 10 July 2018
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Abstract
Electrowetting-on-dielectric (EWOD) has been widely exploited as an actuating force to manipulate liquids by surface tension and modulation of the contact angle on a microscale. To evaluate EWOD, an optical measurement of the droplet contact angle is conventional, but is constrained by the
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Electrowetting-on-dielectric (EWOD) has been widely exploited as an actuating force to manipulate liquids by surface tension and modulation of the contact angle on a microscale. To evaluate EWOD, an optical measurement of the droplet contact angle is conventional, but is constrained by the optical properties of the liquid, especially when two liquid phases (e.g., water in oil) are involved. We developed a non-optical method to study EWOD using a quartz-crystal microbalance (QCM). A QCM provides a promising technique for mass sensing, and has been developed for the study of liquid viscosity, density and contact angle. In this research, a QCM was employed to generate EWOD and concurrently to measure the variation of the contact angle. The contact angle of droplets of water in air and in oil was evaluated. The voltage-dependent oil film between a water droplet and the QCM surface was sensed. A modified QCM model considering a voltage-dependent oil film was derived for the analysis of the contact angle. Full article
(This article belongs to the Special Issue Microfluidics and Nanofluidics)
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Open AccessArticle Pre-Processing of Energy Demand Disaggregation Based Data Mining Techniques for Household Load Demand Forecasting
Received: 3 June 2018 / Revised: 25 June 2018 / Accepted: 4 July 2018 / Published: 8 July 2018
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Abstract
Demand side management has a vital role in supporting the demand response in smart grid infrastructure, in the decision-making of energy management, in household applications is significantly affected by the load-forecasting accuracy. This paper introduces an innovative methodology to enhance household demand forecasting
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Demand side management has a vital role in supporting the demand response in smart grid infrastructure, in the decision-making of energy management, in household applications is significantly affected by the load-forecasting accuracy. This paper introduces an innovative methodology to enhance household demand forecasting based on energy disaggregation for Short Term Load Forecasting. This approach is constructed from Feed-Forward Artificial Neural Network forecaster and a pre-processing stage of energy disaggregation. This disaggregation technique extracts the individual appliances’ load demand profile from the aggregated household load demand to increase the training data window for the proposed forecaster. These proposed algorithms include two benchmark disaggregation algorithms; Factorial Hidden Markov Model (FHMM), Combinatorial Optimization in addition to three adopted Deep Neural Network; long short- term memory (LSTM), Denoising Autoencoder, and a network which regress start time, end time, and average power. The proposed load forecasting approach outperformed the currently available state-of-the-art techniques; namely root mean square error (RMSE), normalized root mean square error (NRMSE), and mean absolute error (MAE). Full article
(This article belongs to the Special Issue Emerging Technologies Enabling Smart Grid)
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Open AccessCommunication Sponsored Libre Research Agreements to Create Free and Open Source Software and Hardware
Received: 25 May 2018 / Revised: 3 July 2018 / Accepted: 4 July 2018 / Published: 6 July 2018
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Abstract
As a growing number of companies reject intellectual property (IP) monopoly-based business models to embrace libre product development of free and open source hardware and software, there is an urgent need to refurbish the instruments of university-corporate research partnerships. These partnerships generally use
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As a growing number of companies reject intellectual property (IP) monopoly-based business models to embrace libre product development of free and open source hardware and software, there is an urgent need to refurbish the instruments of university-corporate research partnerships. These partnerships generally use a proprietary standard research agreement (PSRA), which for historical reasons contains significant IP monopoly language and restrictions for both the company and the university. Such standard research agreements thus create an artificial barrier to innovation as both companies using a libre model and universities they wish to collaborate with must invest significantly to restructure the contracts. To solve this problem, this article provides a new Sponsored Libre Research Agreement (SLRA). The differences between the agreements are detailed. The advantages of using an SLRA are provided for any type of company and include: (1) minimizing research investments on reporting requirements; (2) reducing delays related to confidentiality and publication embargos; and (3) reducing both transaction and legal costs as well as research time losses associated with IP. Moving to libre agreements both speeds up and reduces costs for setting up collaborative research. Under the SLRA, university researchers can spend more time innovating for the same investment. Full article
(This article belongs to the collection Feature Innovation Papers)
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Open AccessReview Inventions and Innovations in Preclinical Platforms for Cancer Research
Received: 29 May 2018 / Revised: 24 June 2018 / Accepted: 27 June 2018 / Published: 3 July 2018
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Abstract
Three-dimensional (3D) cell culture systems can be regarded as suitable platforms to bridge the huge gap between animal studies and two-dimensional (2D) monolayer cell culture to study chronic diseases such as cancer. In particular, the preclinical platforms for multicellular spheroid formation and culture
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Three-dimensional (3D) cell culture systems can be regarded as suitable platforms to bridge the huge gap between animal studies and two-dimensional (2D) monolayer cell culture to study chronic diseases such as cancer. In particular, the preclinical platforms for multicellular spheroid formation and culture can be regarded as ideal in vitro tumour models. The complex tumour microenvironment such as hypoxic region and necrotic core can be recapitulated in 3D spheroid configuration. Cells aggregated in spheroid structures can better illustrate the performance of anti-cancer drugs as well. Various methods have been proposed so far to create such 3D spheroid aggregations. Both conventional techniques and microfluidic methods can be used for generation of multicellular spheroids. In this review paper, we first discuss various spheroid formation phases. Then, the conventional spheroid formation techniques such as bioreactor flasks, liquid overlay and hanging droplet technique are explained. Next, a particular topic of the hydrogel in spheroid formation and culture is explored. This topic has received less attention in the literature. Hydrogels entail some advantages to the spheroid formation and culture such as size uniformity, the formation of porous spheroids or hetero-spheroids as well as chemosensitivity and invasion assays and protecting from shear stress. Finally, microfluidic methods for spheroid formation and culture are briefly reviewed. Full article
(This article belongs to the Section Inventions and innovation in Biotechnology and Materials)
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Open AccessArticle Heat Transfer Performance Enhancement of Gravity Heat Pipes by Growing AAO Nanotubes on Inner Wall Surface
Received: 31 May 2018 / Revised: 26 June 2018 / Accepted: 28 June 2018 / Published: 30 June 2018
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Abstract
In this paper, the heat transfer performance of gravity heat pipes with anodic aluminum oxide (AAO) wall surface is studied. The main purpose is to study the effects of the length and diameter of AAO nanotubes on the temperature distribution, overall thermal resistance,
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In this paper, the heat transfer performance of gravity heat pipes with anodic aluminum oxide (AAO) wall surface is studied. The main purpose is to study the effects of the length and diameter of AAO nanotubes on the temperature distribution, overall thermal resistance, and dry-out occurrence of gravity heat pipes charged with acetone under different input heat powers. AAO nanotubes were first grown by anodizing the inner wall surface of the evaporator section of aluminum alloy gravity heat pipes. The influences of AAO nanotube length and diameter on the temperature distribution, overall thermal resistance, and dry-out occurrence were then investigated by a thermal performance test system. Experimental results show that increasing the AAO nanotube length could result in reduced temperature variation between the evaporator section and the condenser section, leading to reduced thermal resistance, and delayed dry-out occurrence at higher heat inputs. In addition, increasing the AAO nanotube diameter could also cause decreases in temperature variation and overall thermal resistance, but it could not have a significant effect on the occurrence of dry-out phenomenon. Based on these results, it can be concluded that, if the anodic oxidation treatment is applied to the inner wall surface of the evaporator section of a gravity heat pipe, its heat transfer performance could be significantly improved. The maximum temperature difference and overall thermal resistance of the processed heat pipe are 46.12% and 58.68% lower than those of the unprocessed heat pipe, respectively; moreover, compared to the unprocessed heat pipe, the maximum applicable input heat power to avoid dry-out occurrence can be increased up to about 40%. Such a study could be used for cooling purposes in a wide range of applications such as passive cooling of electronic devices, highly efficient heat recovery, and cleanroom air conditioning. Full article
(This article belongs to the Special Issue Heat Transfer and Its Innovative Applications)
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Open AccessReview A Review of Artificial Intelligence Algorithms Used for Smart Machine Tools
Received: 19 April 2018 / Revised: 8 June 2018 / Accepted: 26 June 2018 / Published: 27 June 2018
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Abstract
This paper offers a review of the artificial intelligence (AI) algorithms and applications presently being used for smart machine tools. These AI methods can be classified as learning algorithms (deep, meta-, unsupervised, supervised, and reinforcement learning) for diagnosis and detection of faults in
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This paper offers a review of the artificial intelligence (AI) algorithms and applications presently being used for smart machine tools. These AI methods can be classified as learning algorithms (deep, meta-, unsupervised, supervised, and reinforcement learning) for diagnosis and detection of faults in mechanical components and AI technique applications in smart machine tools including intelligent manufacturing, cyber-physical systems, mechanical components prognosis, and smart sensors. A diagram of the architecture of AI schemes used for smart machine tools has been included. The respective strengths and weaknesses of the methods, as well as the challenges and future trends in AI schemes, are discussed. In the future, we will propose several AI approaches to tackle mechanical components as well as addressing different AI algorithms to deal with smart machine tools and the acquisition of accurate results. Full article
(This article belongs to the Special Issue Selected Papers from ICI2017 and Spintech Thesis Awards)
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Open AccessArticle The Separation of Microalgae Using Dean Flow in a Spiral Microfluidic Device
Received: 15 May 2018 / Revised: 16 June 2018 / Accepted: 18 June 2018 / Published: 21 June 2018
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Abstract
A cell-in-droplet encapsulation using Dean flow in a spiral microfluidic device was applied to separate microalgae. In recent years, researchers have been interested in separating micro particles using microfluidic chips because of its great advantages in relation to various applications such as in
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A cell-in-droplet encapsulation using Dean flow in a spiral microfluidic device was applied to separate microalgae. In recent years, researchers have been interested in separating micro particles using microfluidic chips because of its great advantages in relation to various applications such as in biotechnology, medical examination, and cell studies. The main disadvantage of these microfluidic chips is particle clogging that decreases the separation yield, which then creates difficulties during the investigation of the particles. The microfluidic chip that is introduced in this work is a combination of two distinct designs—a spiral microchannel design to separate microalgae of various sizes, and a microdroplet generation design for cell encapsulation. The yield of the separation is enhanced through the concept of dominant forces (Dean drag force and lift force) in a spiral microchannel design, together with a design of the microdroplet generation that narrows the volume to facilitate cell observation. We report the development of cells, particle separation, and microdroplet generation. Using the spiral microchannel design can solve the clogging problem by distributing the microalgae evenly for the microdroplet generation section. A spiral microfluidics design was used as a separator for the different sized particles and a microdroplets generation design was used to encapsulate the separated particles. As for the design for the microdroplets generation section, a 3-way microchannel was designed. In this research, two kinds of microalgae have been used: the smaller one is chlorella vulgaris and the bigger one is cosmarium. Because of all of these benefits, this device might be an alternative for cell applications using droplet-based platforms. With a different channel height design, the separation efficiency for Chlorella vulgaris is about 75–80% and for Cosmarium is about 60–72%. Full article
(This article belongs to the Special Issue Microfluidics and Nanofluidics)
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