Applied Sciences

2487 KiB

Open AccessArticle

Improved Permeate Flux of PVDF Ultrafiltration Membrane Containing PVDF-g-PHEA Synthesized via ATRP

by Kwang-Mo Kim, Sahng Hyuck Woo, Ju Sung Lee, Hyun Sic Park, Jinwon Park and Byoung Ryul Min

Appl. Sci. 2015, 5(4), 1992-2008; https://doi.org/10.3390/app5041992 - 21 Dec 2015

Cited by 17 | Viewed by 7949

Polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane combined with polyvinylidene fluoride-graft-2-hydroxyethyl acrylate (PVDF-g-PHEA) was fabricated via non-solvent induced phase separation (NIPS). In this study, PVDF-g-PHEA was synthesized via atom transfer radical polymerization (ATRP) method, and then synthesized graft copolymer was characterized using Fourier transform [...] Read more.

Polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane combined with polyvinylidene fluoride-graft-2-hydroxyethyl acrylate (PVDF-g-PHEA) was fabricated via non-solvent induced phase separation (NIPS). In this study, PVDF-g-PHEA was synthesized via atom transfer radical polymerization (ATRP) method, and then synthesized graft copolymer was characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and thermogravimetry analysis (TGA). Moreover, PVDF membranes containing graft copolymer (PVDF-g-PHEA) showed lower water contact angle value than pristine PVDF membranes. Macrovoid holes were also observed in cross sectional scanning electron microscope (SEM) image of PVDF membrane containing PVDF-g-PHEA. Accordingly, it was confirmed that these characteristics led PVDF membrane blended with graft copolymer has high final permeate flux and normalized flux compared to pristine PVDF membrane. Full article

(This article belongs to the Special Issue Organo-Fluorine Chemical Science)

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13682 KiB

Open AccessArticle

Image Hiding Scheme Based on the Atrial Fibrillation Model

by Martynas Vaidelys, Jurate Ragulskiene, Pranas Ziaukas and Minvydas Ragulskis

Appl. Sci. 2015, 5(4), 1980-1991; https://doi.org/10.3390/app5041980 - 21 Dec 2015

Cited by 4 | Viewed by 5694

Abstract

An image communication scheme based on the atrial fibrillation (AF) model is presented in this paper. Self-organizing patterns produced by the AF model are used to hide and transmit secret visual information. A secret image is encoded into the random matrix of initial [...] Read more.

An image communication scheme based on the atrial fibrillation (AF) model is presented in this paper. Self-organizing patterns produced by the AF model are used to hide and transmit secret visual information. A secret image is encoded into the random matrix of initial cell excitation states in the form of a dot-skeleton representation. Self-organized patterns produced by such initial cell states ensure a secure and efficient transmission of secret visual images. Procedures for digital encoding and decoding of secret images, as well as the sensitivity of the communication scheme to the perturbation of the AF model’s parameters are discussed in the paper. Full article

(This article belongs to the Special Issue Intelligence Computational and Control Approaches for Multi-Physic Coupling Engineering Systems)

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4690 KiB

Open AccessFeature PaperArticle

Generation of 25-TW Femtosecond Laser Pulses at 515 nm with Extremely High Temporal Contrast

by Marco Hornung, Georg Alexander Becker, Andreas Seidel, Jan Reislöhner, Hartmut Liebetrau, Lennart Bock, Sebastian Keppler, Alexander Kessler, Matthew Zepf, Joachim Hein and Malte Christoph Kaluza

Appl. Sci. 2015, 5(4), 1970-1979; https://doi.org/10.3390/app5041970 - 19 Dec 2015

Cited by 11 | Viewed by 6696

Abstract

We report on the frequency doubling of femtosecond laser pulses at 1030 nm center wavelength generated from the fully diode-pumped laser system POLARIS. The newly generated pulses at a center wavelength of 515 nm have a pulse energy of 3 J with a [...] Read more.

We report on the frequency doubling of femtosecond laser pulses at 1030 nm center wavelength generated from the fully diode-pumped laser system POLARIS. The newly generated pulses at a center wavelength of 515 nm have a pulse energy of 3 J with a pulse duration of 120 fs. On the basis of initially ultra-high contrast seed pulses we expect a temporal intensity contrast better 10 17 200 ps before the peak of the main pulse. We analyzed the temporal intensity contrast from milliseconds to femtoseconds with a dynamic range covering more than 20 orders of magnitude. The pulses were focussed with a f/2-focussing parabola resulting in a peak intensity exceeding 10 20 W / cm 2 . The peak power and intensity are to the best of our knowledge the highest values for 515 nm-laser-pulses achieved so far. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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801 KiB

Open AccessArticle

Main Leaf Polyphenolic Components of Berry Color Variant Grapevines and Their Acclimative Responses to Sunlight Exposure

by Marianna Kocsis, László Abrankó, Ferhan Ayaydin, Kristóf Csepregi, Nóra Papp, Péter Teszlák and Gábor Jakab

Appl. Sci. 2015, 5(4), 1955-1969; https://doi.org/10.3390/app5041955 - 18 Dec 2015

Cited by 7 | Viewed by 5538

Abstract

Grapevine leaf synthesizes a wide variety of bioactive secondary metabolites, including polyphenols, which are also key components in ensuring development and growth of the whole plant even under adverse environmental conditions. Our study evaluates the nonanthocyanin polyphenolic composition in grapevine leaves of three [...] Read more.

Grapevine leaf synthesizes a wide variety of bioactive secondary metabolites, including polyphenols, which are also key components in ensuring development and growth of the whole plant even under adverse environmental conditions. Our study evaluates the nonanthocyanin polyphenolic composition in grapevine leaves of three varieties of Gohér conculta (Vitis vinifera L.) native to Hungary. A high performance liquid chromatography (HPLC) system including a diode array detector (DAD) coupled to a time-of-flight mass spectrometer (q-TOFMS) was successfully applied to profile intact glycoconjugate forms in samples. In-source fragmentation was utilized in order to provide structural information on the compounds. Using this method, the presence of 16 polyphenolic metabolites were confirmed, and eight of them were subjected to further quantification in sun acclimated and half shaded leaves. Intracellular microimaging detected accumulation of flavonols in cell nuclei, cell wall and chloroplasts. Our findings demonstrated that Gohér conculta—a special grapevine taxon of our viticultural heritage with berry color variants—is a suitable model to study the interaction between genetic and environmental factors in determination of grapevine phenolic composition. Full article

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2689 KiB

Open AccessArticle

A Novel Piezoelectric Energy Harvester Using the Macro Fiber Composite Cantilever with a Bicylinder in Water

by Rujun Song, Xiaobiao Shan, Fengchi Lv, Jinzhe Li and Tao Xie

Appl. Sci. 2015, 5(4), 1942-1954; https://doi.org/10.3390/app5041942 - 17 Dec 2015

Cited by 64 | Viewed by 9232

Abstract

A novel piezoelectric energy harvester equipped with two piezoelectric beams and two cylinders was proposed in this work. The energy harvester can convert the kinetic energy of water into electrical energy by means of vortex-induced vibration (VIV) and wake-induced vibration (WIV). The effects [...] Read more.

A novel piezoelectric energy harvester equipped with two piezoelectric beams and two cylinders was proposed in this work. The energy harvester can convert the kinetic energy of water into electrical energy by means of vortex-induced vibration (VIV) and wake-induced vibration (WIV). The effects of load resistance, water velocity and cylinder diameter on the performance of the harvester were investigated. It was found that the vibration of the upstream cylinder was VIV which enhanced the energy harvesting capacity of the upstream piezoelectric beam. As for the downstream cylinder, both VIV and the WIV could be obtained. The VIV was found with small L/D, e.g., 2.125, 2.28, 2.5, and 2.8. Additionally, the WIV was stimulated with the increase of L/D (such as 3.25, 4, and 5.5). Due to the WIV, the downstream beam presented better performance in energy harvesting with the increase of water velocity. Furthermore, it revealed that more electrical energy could be obtained by appropriately matching the resistance and the diameter of the cylinder. With optimal resistance (170 kΩ) and diameter of the cylinder (30 mm), the maximum output power of 21.86 μW (sum of both piezoelectric beams) was obtained at a water velocity of 0.31 m/s. Full article

(This article belongs to the Special Issue Ferroelectric Ceramics)

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726 KiB

Open AccessArticle

Self-Seeded RSOA-Fiber Cavity Lasers vs. ASE Spectrum-Sliced or Externally Seeded Transmitters—A Comparative Study

by Simon A. Gebrewold, Romain Bonjour, Sophie Barbet, Anaelle Maho, Romain Brenot, Philippe Chanclou, Marco Brunero, Lucia Marazzi, Paola Parolari, Angelina Totovic, Dejan Gvozdic, David Hillerkuss, Christian Hafner and Juerg Leuthold

Appl. Sci. 2015, 5(4), 1922-1941; https://doi.org/10.3390/app5041922 - 17 Dec 2015

Cited by 8 | Viewed by 6597

Abstract

Reflective semiconductor optical amplifier fiber cavity lasers (RSOA-FCLs) are appealing, colorless, self-seeded, self-tuning and cost-efficient upstream transmitters. They are of interest for wavelength division multiplexed passive optical networks (WDM-PONs) based links. In this paper, we compare RSOA-FCLs with alternative colorless sources, namely the [...] Read more.

Reflective semiconductor optical amplifier fiber cavity lasers (RSOA-FCLs) are appealing, colorless, self-seeded, self-tuning and cost-efficient upstream transmitters. They are of interest for wavelength division multiplexed passive optical networks (WDM-PONs) based links. In this paper, we compare RSOA-FCLs with alternative colorless sources, namely the amplified spontaneous emission (ASE) spectrum-sliced and the externally seeded RSOAs. We compare the differences in output power, signal-to-noise ratio (SNR), relative intensity noise (RIN), frequency response and transmission characteristics of these three sources. It is shown that an RSOA-FCL offers a higher output power over an ASE spectrum-sliced source with SNR, RIN and frequency response characteristics halfway between an ASE spectrum-sliced and a more expensive externally seeded RSOA. The results show that the RSOA-FCL is a cost-efficient WDM-PON upstream source, borrowing simplicity and cost-efficiency from ASE spectrum slicing with characteristics that are, in many instances, good enough to perform short-haul transmission. To substantiate our statement and to quantitatively compare the potential of the three schemes, we perform data transmission experiments at 5 and 10 Gbit/s. Full article

(This article belongs to the Special Issue Fibre Lasers: From Underlying Science and Technology to Applications)

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1983 KiB

Open AccessArticle

Thermal Lattice Boltzmann Simulation of Entropy Generation within a Square Enclosure for Sensible and Latent Heat Transfers

by Alissar Yehya and Hassane Naji

Appl. Sci. 2015, 5(4), 1904-1921; https://doi.org/10.3390/app5041904 - 17 Dec 2015

Cited by 10 | Viewed by 4606

Abstract

This paper deals with the numerical simulation of heat transfer and entropy generation in a 2D square enclosure for convective melting. A thermal lattice Boltzmann method (TLBM) is used to handle the study, which has been conducted for Prandtl numbers from 0.02 to [...] Read more.

This paper deals with the numerical simulation of heat transfer and entropy generation in a 2D square enclosure for convective melting. A thermal lattice Boltzmann method (TLBM) is used to handle the study, which has been conducted for Prandtl numbers from 0.02 to 70 at Rayleigh numbers of 10⁴ and 10⁵. The results are presented in terms of the total entropy generation, average Bejan number and average Nusselt number. Within the range considered for the key parameters, the entropy generation is found to be controlled by the heat transfer loss for low Prandtl numbers. However, for the large Prandtl numbers, its variation is dominated by shearing losses. Moreover, the presence of the latent heat state decreases the overall thermodynamic losses while increasing the quantity of heat transferred. Full article

(This article belongs to the Special Issue Phase Change Materials (PCM))

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2894 KiB

Open AccessArticle

Design and Implementation of an IoT Access Point for Smart Home

by Chih-Yung Chang, Chin-Hwa Kuo, Jian-Cheng Chen and Tzu-Chia Wang

Appl. Sci. 2015, 5(4), 1882-1903; https://doi.org/10.3390/app5041882 - 16 Dec 2015

Cited by 46 | Viewed by 11554

Abstract

Network communication and micro-electro-mechanical embedded technologies have attracted much attention in recent years. Through these technologies, the capabilities of sensing, identification, and communication can be embedded in various smart devices. These smart devices can automatically connect to the Internet and form an intelligent [...] Read more.

Network communication and micro-electro-mechanical embedded technologies have attracted much attention in recent years. Through these technologies, the capabilities of sensing, identification, and communication can be embedded in various smart devices. These smart devices can automatically connect to the Internet and form an intelligent network called Internet of Things (IoT). However, these devices are embedded with different wireless communication interfaces such as Wi-Fi and ZigBee. This paper presents the design and implementation of an IoT access point that supports functionalities of coordination of various wireless transmission protocols. Based on the existing Wi-Fi access point, we have embedded a ZigBee module and implemented ZigBee and UPnP protocols into the designed IoT access point, which supports ZigBee communication capabilities over the Internet. Full article

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5187 KiB

Open AccessArticle

Kinetic Adsorption Study of Silver Nanoparticles on Natural Zeolite: Experimental and Theoretical Models

by Alvaro Ruíz-Baltazar and Ramiro Pérez

Appl. Sci. 2015, 5(4), 1869-1881; https://doi.org/10.3390/app5041869 - 16 Dec 2015

Cited by 17 | Viewed by 6504

Abstract

In this research, the adsorption capacity of Ag nanoparticles on natural zeolite from Oaxaca is presented. In order to describe the adsorption mechanism of silver nanoparticles on zeolite, experimental adsorption models for Ag ions and Ag nanoparticles were carried out. These experimental data [...] Read more.

In this research, the adsorption capacity of Ag nanoparticles on natural zeolite from Oaxaca is presented. In order to describe the adsorption mechanism of silver nanoparticles on zeolite, experimental adsorption models for Ag ions and Ag nanoparticles were carried out. These experimental data obtained by the atomic absorption spectrophotometry technique were compared with theoretical models such as Lagergren first-order, pseudo-second-order, Elovich, and intraparticle diffusion. Correlation factors R² of the order of 0.99 were observed. Analysis by transmission electron microscopy describes the distribution of the silver nanoparticles on the zeolite outer surface. Additionally, a chemical characterization of the material was carried out through a dilution process with lithium metaborate. An average value of 9.3 in the Si/Al ratio was observed. Factors such as the adsorption behavior of the silver ions and the Si/Al ratio of the zeolite are very important to support the theoretical models and establish the adsorption mechanism of Ag nanoparticles on natural zeolite. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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5381 KiB

Open AccessArticle

Numerical Simulation of Laminar Forced Convection of Pin-Fin Heat-Sink Array in a Channel by Using Porous Approach

by Tzer-Ming Jeng and Sheng-Chung Tzeng

Appl. Sci. 2015, 5(4), 1846-1868; https://doi.org/10.3390/app5041846 - 16 Dec 2015

Cited by 10 | Viewed by 7880

Abstract

This work used a porous approach model to numerically investigate the fluid flow and heat transfer characteristics of the pin-fin heat-sink array in a rectangular channel with in-line arrangement. The air flow through the channel was laminar. The pin-fin heat sinks with various [...] Read more.

This work used a porous approach model to numerically investigate the fluid flow and heat transfer characteristics of the pin-fin heat-sink array in a rectangular channel with in-line arrangement. The air flow through the channel was laminar. The pin-fin heat sinks with various porosities and pin-fin numbers were employed. The relative center-to-center longitudinal and transverse distances between adjacent heat sinks were changed. The results indicate that the Nusselt number of various heat-sink arrays increased with decreasing the relative center-to-center transverse distance, but not varied with the relative center-to-center longitudinal distance. For the typical pin-fin heat-sink arrays, the Nusselt number changed slightly for the heat sinks with 0.358–0.556 porosity, but increased by 11.7%–24.8% when the porosity increased from 0.556 to 0.750, and then dropped obviously when the porosity exceeded 0.750. Increasing the number of pin fins continuously could increase Nusselt number. However, when the number of pin fins was large, the Nusselt number increased with the number of pin fins slowly. The present numerical simulation has been validated by the typical experiment. Finally, a semi-empirical correlation of Nusselt number for each heat sink in the heat-sink array was proposed. Full article

(This article belongs to the Special Issue Intelligence Computational and Control Approaches for Multi-Physic Coupling Engineering Systems)

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826 KiB

Open AccessArticle

High Power Diode-Side-Pumped Q-Switched Nd:YAG Solid-State Laser with a Thermoelectric Cooler

by Jian Dong, Xue-Sheng Liu, Chao Peng, You-Qiang Liu and Zhi-Yong Wang

Appl. Sci. 2015, 5(4), 1837-1845; https://doi.org/10.3390/app5041837 - 16 Dec 2015

Cited by 16 | Viewed by 7246

Abstract

A diode-side-pumped, high-energy, high-beam-quality, pulsed solid-state Nd³⁺:Y₃Al₅O₁₂ (Nd:YAG) laser with a thermoelectric cooler (TEC) is investigated in this study. The pump laser was a pulsed laser diode array with maximum peak power of 15 kW. A [...] Read more.

A diode-side-pumped, high-energy, high-beam-quality, pulsed solid-state Nd³⁺:Y₃Al₅O₁₂ (Nd:YAG) laser with a thermoelectric cooler (TEC) is investigated in this study. The pump laser was a pulsed laser diode array with maximum peak power of 15 kW. A 350 mJ laser pulse was obtained with a wavelength of 1064 nm, a pulse duration of 10 ns, a total electrical-to-optical efficiency of 7.5%, a relative stability of output energy of 5%, and a beam quality of M² < 4. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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1618 KiB

Open AccessReview

Sequentially Palladium-Catalyzed Processes in One-Pot Syntheses of Heterocycles

by Timo Lessing and Thomas J. J. Müller

Appl. Sci. 2015, 5(4), 1803-1836; https://doi.org/10.3390/app5041803 - 16 Dec 2015

Cited by 38 | Viewed by 8340

Abstract

Sequentially Pd-catalyzed processes are excellent entries to heterocycle synthesis. The broad mechanistic variety combined with often very mild reaction conditions allow the concatenation of elementary organic and organometallic steps to novel sequences in the sense of one-pot domino and multicomponent reactions. Given the [...] Read more.

Sequentially Pd-catalyzed processes are excellent entries to heterocycle synthesis. The broad mechanistic variety combined with often very mild reaction conditions allow the concatenation of elementary organic and organometallic steps to novel sequences in the sense of one-pot domino and multicomponent reactions. Given the numerous opportunities of alkyne coordination and their Pd-mediated transformations, alkynylation and carbometallation play a key role, both for purely organometallic sequences as well as in those processes that are intercepted by cyclocondensation. Pd-catalyzed aminations also find more and more entry into novel heterocycle syntheses based upon this theme. Full article

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3035 KiB

Open AccessArticle

Temporal Shaping of High Peak Power Pulse Trains from a Burst-Mode Laser System

by Jörg Körner, Jürgen Reiter, Joachim Hein and Malte C. Kaluza

Appl. Sci. 2015, 5(4), 1790-1802; https://doi.org/10.3390/app5041790 - 15 Dec 2015

Cited by 6 | Viewed by 5689

Abstract

It has been shown in the past that pulsed laser systems operating in the so-called “burst mode” are a beneficial approach to generate high peak power laser pulses at high repetition rates suitable for various applications. So far, most high-energy burst-mode laser systems [...] Read more.

It has been shown in the past that pulsed laser systems operating in the so-called “burst mode” are a beneficial approach to generate high peak power laser pulses at high repetition rates suitable for various applications. So far, most high-energy burst-mode laser systems put great effort into generating a homogeneous energy distribution across the burst duration, e.g., by shaping the pump pulse. In this work, we present a new shaping technique, which is able to produce arbitrary energy distributions within the burst by pre-shaping the seed pulse burst with a Pockels cell. Furthermore, this technique allows for the precompensation of any static modulations across the burst, which may be introduced during the subsequent amplification process. Therefore, a pulse burst with a uniform energy distribution can also be generated. The method is tested with an ultra-short pulse burst mode laser amplifier system producing bursts of a 1 ms duration with a pulse repetition rate of 1 MHz and a maximum output power of 800 W during the burst. Furthermore, a method to predict the influence of the amplifier on a non-uniformly shaped burst is presented and successfully tested to produce a pre-defined pulse shape after amplification. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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324 KiB

Open AccessArticle

On the Design of an Elegant CFO Estimate System with the Assistance of Pilots for OFDM Transmission

by Tsui-Tsai Lin and Fuh-Hsin Hwang

Appl. Sci. 2015, 5(4), 1773-1789; https://doi.org/10.3390/app5041773 - 12 Dec 2015

Cited by 1 | Viewed by 3683

Abstract

We present an improved line search method of the carrier frequency offset (CFO) estimate technique for OFDM systems aided with pilots. Unlike the conventional approaches, prior knowledge of channel order is unnecessary for the presented scheme, because we apply an interpolation technique for [...] Read more.

We present an improved line search method of the carrier frequency offset (CFO) estimate technique for OFDM systems aided with pilots. Unlike the conventional approaches, prior knowledge of channel order is unnecessary for the presented scheme, because we apply an interpolation technique for obtaining the extended channel frequency response. The search mechanism of the proposed approach is primarily based on the criterion that CFO can be found by discovering the frequency that achieves the minimum value of the well-defined channel residual energy. In addition, we substitute the line search method with an iterative approach to reduce the proposed estimator’s complexity. Analytical and simulation results have been conducted to verify the efficacy of the proposed schemes in this paper. Full article

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386 KiB

Open AccessArticle

A Modified Feature Selection and Artificial Neural Network-Based Day-Ahead Load Forecasting Model for a Smart Grid

by Ashfaq Ahmad, Nadeem Javaid, Nabil Alrajeh, Zahoor Ali Khan, Umar Qasim and Abid Khan

Appl. Sci. 2015, 5(4), 1756-1772; https://doi.org/10.3390/app5041756 - 11 Dec 2015

Cited by 46 | Viewed by 6033

Abstract

In the operation of a smart grid (SG), day-ahead load forecasting (DLF) is an important task. The SG can enhance the management of its conventional and renewable resources with a more accurate DLF model. However, DLF model development is highly challenging due to [...] Read more.

In the operation of a smart grid (SG), day-ahead load forecasting (DLF) is an important task. The SG can enhance the management of its conventional and renewable resources with a more accurate DLF model. However, DLF model development is highly challenging due to the non-linear characteristics of load time series in SGs. In the literature, DLF models do exist; however, these models trade off between execution time and forecast accuracy. The newly-proposed DLF model will be able to accurately predict the load of the next day with a fair enough execution time. Our proposed model consists of three modules; the data preparation module, feature selection and the forecast module. The first module makes the historical load curve compatible with the feature selection module. The second module removes redundant and irrelevant features from the input data. The third module, which consists of an artificial neural network (ANN), predicts future load on the basis of selected features. Moreover, the forecast module uses a sigmoid function for activation and a multi-variate auto-regressive model for weight updating during the training process. Simulations are conducted in MATLAB to validate the performance of our newly-proposed DLF model in terms of accuracy and execution time. Results show that our proposed modified feature selection and modified ANN (m(FS + ANN))-based model for SGs is able to capture the non-linearity(ies) in the history load curve with 97 . 11 % accuracy. Moreover, this accuracy is achieved at the cost of a fair enough execution time, i.e., we have decreased the average execution time of the existing FS + ANN-based model by 38 . 50 % . Full article

(This article belongs to the Special Issue Applied Artificial Neural Network)

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1490 KiB

Open AccessArticle

Enhancement Effects of the Terahertz Near-Field Microscopy

by Jian Huang, Zhongbo Yang, Dongshan Wei, Chunlei Du and Hong-Liang Cui

Appl. Sci. 2015, 5(4), 1745-1755; https://doi.org/10.3390/app5041745 - 11 Dec 2015

Cited by 8 | Viewed by 5795

Abstract

Terahertz near-field detection based and imaging on a nanotip has drawn wide attention following extensive applications of terahertz imaging technologies. Through the local enhanced electric field created by a terahertz nanotip in the near field, it is very likely to attain superior detection [...] Read more.

Terahertz near-field detection based and imaging on a nanotip has drawn wide attention following extensive applications of terahertz imaging technologies. Through the local enhanced electric field created by a terahertz nanotip in the near field, it is very likely to attain superior detection sensitivity and higher spatial resolution. This paper simulates the local enhancement effects of the terahertz near-field microscopy using a two-dimension finite difference time domain (2D-FDTD) method. Factors that influence the enhancement effects are investigated and analyzed in detail. Simulation results show that the size of the nanotip apex, the apex-substrate distance, dielectric properties of the substrate and the detected sample, etc., have significant impacts on the electric field enhancement and spatial resolution of the terahertz near-field nanotip, which can be explained from the effective polarizability of the nanotip-sample/substrate system. Full article

(This article belongs to the Special Issue Frontiers in Terahertz Science and Technology)

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2521 KiB

Open AccessArticle

Optical Simulation of Light Management in CIGS Thin-Film Solar Cells Using Finite Element Method

by Nikola Bednar, Noemi Severino and Nadja Adamovic

Appl. Sci. 2015, 5(4), 1735-1744; https://doi.org/10.3390/app5041735 - 11 Dec 2015

Cited by 21 | Viewed by 6995

Abstract

In this paper we present an optical simulation of light management in Cu(In,Ga)Se₂ thin-film solar cells with reduced absorber layer thickness, with the goal of absorption enhancement in the absorber layer. The light management was achieved by texturing of the substrate layer, [...] Read more.

In this paper we present an optical simulation of light management in Cu(In,Ga)Se₂ thin-film solar cells with reduced absorber layer thickness, with the goal of absorption enhancement in the absorber layer. The light management was achieved by texturing of the substrate layer, and the conformal growth of all the following layers was assumed. Two texturing shapes have been explored: triangular and convex, with different periods and height aspect ratios. The simulations have shown that significant enhancement of absorption within the absorber layer can be achieved using the proposed geometry. The results showed that the triangular textures with small periods (100–200 nm) and high aspect ratios have the most prominent effect on the enhancement of absorption within the absorber layer, although they are difficult to achieve experimentally. Full article

(This article belongs to the Special Issue Selected Papers from the 2nd Spring International School and Workshop of Nanotechnology for the Next Generation High Efficiency Photovoltaics)

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2840 KiB

Open AccessArticle

Electromagnetic Acoustic Transducers Applied to High Temperature Plates for Potential Use in the Solar Thermal Industry

by Maria Kogia, Liang Cheng, Abbas Mohimi, Vassilios Kappatos, Tat-Hean Gan, Wamadeva Balachandran and Cem Selcuk

Appl. Sci. 2015, 5(4), 1715-1734; https://doi.org/10.3390/app5041715 - 11 Dec 2015

Cited by 15 | Viewed by 6067

Abstract

Concentrated Solar Plants (CSPs) are used in solar thermal industry for collecting and converting sunlight into electricity. Parabolic trough CSPs are the most widely used type of CSP and an absorber tube is an essential part of them. The hostile operating environment of [...] Read more.

Concentrated Solar Plants (CSPs) are used in solar thermal industry for collecting and converting sunlight into electricity. Parabolic trough CSPs are the most widely used type of CSP and an absorber tube is an essential part of them. The hostile operating environment of the absorber tubes, such as high temperatures (400–550 °C), contraction/expansion, and vibrations, may lead them to suffer from creep, thermo-mechanical fatigue, and hot corrosion. Hence, their condition monitoring is of crucial importance and a very challenging task as well. Electromagnetic Acoustic Transducers (EMATs) are a promising, non-contact technology of transducers that has the potential to be used for the inspection of large structures at high temperatures by exciting Guided Waves. In this paper, a study regarding the potential use of EMATs in this application and their performance at high temperature is presented. A Periodic Permanent Magnet (PPM) EMAT with a racetrack coil, designed to excite Shear Horizontal waves (SH₀), has been theoretically and experimentally evaluated at both room and high temperatures. Full article

(This article belongs to the Special Issue Acoustic and Elastic Waves: Recent Trends in Science and Engineering)

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1315 KiB

Open AccessArticle

Feasibility Study of Sensor Aided Impact Acoustic Sorting of Plastic Materials from End-of-Life Vehicles (ELVs)

by Jiu Huang, Zhengfu Bian and Shaogang Lei

Appl. Sci. 2015, 5(4), 1699-1714; https://doi.org/10.3390/app5041699 - 9 Dec 2015

Cited by 6 | Viewed by 4770

Abstract

The purpose of this feasibility research was to study a novel sensor based separation method for recycling of plastic materials from end-of-life vehicles (ELVs) by using eigen-frequency response of impact acoustic emission. In this research three kinds of commonly used plastics, polypropylene (PP), [...] Read more.

The purpose of this feasibility research was to study a novel sensor based separation method for recycling of plastic materials from end-of-life vehicles (ELVs) by using eigen-frequency response of impact acoustic emission. In this research three kinds of commonly used plastics, polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), and styrene-maleic-anhydride (SMA) sampled from end-of-life vehicles, were researched. Almost all the crushed plastic scraps had a flake structure, theoretically their impact response behaviors were determined by their diameters and thicknesses. The equivalent diameters of the scraps were characterized by fine sieving and their thicknesses were measured online by a 3D laser triangulation sensor above the conveying path. Following this the scraps were free dropped one-by-one to impact with an impact passive body on which impact acoustic emission (AE) signals were generated and acquired by an acoustic pickup sensor. Thirdly, the AE signals which carried eigen-frequency response features were processed and characterized. Results demonstrated that the scraps with diameters < 8 mm were too weak for the actual devices to process; the scraps with diameter from 8–13 mm still generated quite a lot of AE signals of inadequate intensity. Finally the general characterization and recognition yields were 64.6%, 61.7%, and 63.9% of PP, ABS, and SMA in mass, respectively of tested materials. Full article

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2508 KiB

Open AccessArticle

Correlation between Earthquakes and AE Monitoring of Historical Buildings in Seismic Areas

by Giuseppe Lacidogna, Patrizia Cutugno, Gianni Niccolini, Stefano Invernizzi and Alberto Carpinteri

Appl. Sci. 2015, 5(4), 1683-1698; https://doi.org/10.3390/app5041683 - 8 Dec 2015

Cited by 8 | Viewed by 5132

Abstract

In this contribution a new method for evaluating seismic risk in regional areas based on the acoustic emission (AE) technique is proposed. Most earthquakes have precursors, i.e., phenomena of changes in the Earth’s physical-chemical properties that take place prior to an earthquake. [...] Read more.

In this contribution a new method for evaluating seismic risk in regional areas based on the acoustic emission (AE) technique is proposed. Most earthquakes have precursors, i.e., phenomena of changes in the Earth’s physical-chemical properties that take place prior to an earthquake. Acoustic emissions in materials and earthquakes in the Earth’s crust, despite the fact that they take place on very different scales, are very similar phenomena; both are caused by a release of elastic energy from a source located in a medium. For the AE monitoring, two important constructions of Italian cultural heritage are considered: the chapel of the “Sacred Mountain of Varallo” and the “Asinelli Tower” of Bologna. They were monitored during earthquake sequences in their relative areas. By using the Grassberger-Procaccia algorithm, a statistical method of analysis was developed that detects AEs as earthquake precursors or aftershocks. Under certain conditions it was observed that AEs precede earthquakes. These considerations reinforce the idea that the AE monitoring can be considered an effective tool for earthquake risk evaluation. Full article

(This article belongs to the Special Issue Acoustic and Elastic Waves: Recent Trends in Science and Engineering)

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1900 KiB

Open AccessArticle

Monitoring Techniques of Cerium Stabilized Zirconia for Medical Prosthesis

by Adriana Savin, Mihail-Liviu Craus, Vitalii Turchenko, Alina Bruma, Pierre-Antoine Dubos, Sylvie Malo, Tatiana E. Konstantinova and Valerii V. Burkhovetsky

Appl. Sci. 2015, 5(4), 1665-1682; https://doi.org/10.3390/app5041665 - 8 Dec 2015

Cited by 22 | Viewed by 5718

Abstract

The purpose of this paper is to emphasize the improvement of Zr-based ceramics properties as a function of addition of Ce ions in the structure of the original ceramics. The structural investigations proposed in this paper cover X-ray, and neutron diffraction offered the [...] Read more.

The purpose of this paper is to emphasize the improvement of Zr-based ceramics properties as a function of addition of Ce ions in the structure of the original ceramics. The structural investigations proposed in this paper cover X-ray, and neutron diffraction offered the first indication of the variation of the phase composition and the structural parameters, micro-hardness measurements as well as non-destructive evaluations in order to analyze the structural properties of these materials with utmost importance in fields such as medicine, where these composite materials are used in hip-implants or dental implants/coatings. In combination of Resonant Ultrasound Spectroscopy, which makes use of the resonance frequencies corresponding to the normal vibrational modes of a solid in order to evaluate the elastic constants of the materials, we emphasize a unique approach on evaluating the physical properties of these ceramics, which could help in advancing the understanding of properties and applications in medical fields. Full article

(This article belongs to the Special Issue Acoustic and Elastic Waves: Recent Trends in Science and Engineering)

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Open AccessArticle

Magnetohydrodynamic Flow and Heat Transfer of Nanofluids in Stretchable Convergent/Divergent Channels

by Syed Tauseef Mohyud-Din, Umar Khan, Naveed Ahmed and Saleh M. Hassan

Appl. Sci. 2015, 5(4), 1639-1664; https://doi.org/10.3390/app5041639 - 4 Dec 2015

Cited by 88 | Viewed by 6671

Abstract

This article is dedicated to analyzing the heat transfer in the flow of water-based nanofluids in a channel with non-parallel stretchable walls. The magnetohydrodynamic (MHD) nature of the flow is considered. Equations governing the flow are transformed into a system of nonlinear ordinary [...] Read more.

This article is dedicated to analyzing the heat transfer in the flow of water-based nanofluids in a channel with non-parallel stretchable walls. The magnetohydrodynamic (MHD) nature of the flow is considered. Equations governing the flow are transformed into a system of nonlinear ordinary differential equations. The said system is solved by employing two different techniques, the variational iteration method (VIM) and the Runge-Kutta-Fehlberg method (RKF). The influence of the emerging parameters on the velocity and temperature profiles is highlighted with the help of graphs coupled with comprehensive discussions. A comparison with the already existing solutions is also made, which are the special cases of the current problem. It is observed that the temperature profile decreases with an increase in the nanoparticle volume fraction. Furthermore, a magnetic field can be used to control the possible separation caused by the backflows in the case of diverging channels. The effects of parameters on the skin friction coefficient and Nusselt number are also presented using graphical aid. The nanoparticle volume fraction helps to reduce the temperature of the channel and to enhance the rate of heat transfer at the wall. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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861 KiB

Open AccessArticle

Lean-Agile Adaptations in Clinical Laboratory Accredited ISO 15189

by Carlos Vilaplana Pérez, Gloria Soria Guerrero, Federico Garriga Garzón and Angel Salas Garcia

Appl. Sci. 2015, 5(4), 1616-1638; https://doi.org/10.3390/app5041616 - 4 Dec 2015

Cited by 2 | Viewed by 5253

Abstract

It’s introduced Lean techniques in a Clinical Laboratory to improve the operability and the efficiency in continuous processes of analysis, failsafe systems, analysis of areas of value pursuit of zero defects and reduction of waste, and it promote continuous improvement in presented difficulties [...] Read more.

It’s introduced Lean techniques in a Clinical Laboratory to improve the operability and the efficiency in continuous processes of analysis, failsafe systems, analysis of areas of value pursuit of zero defects and reduction of waste, and it promote continuous improvement in presented difficulties in adapting to the changing needs of the healthcare environment. Whereas it is necessary to incorporate certification and accreditation, note that the adaptability of the clinical laboratory to the changing needs of physicians in obtaining analytical information is reduced. The application of an agile methodology on analytical systems can provide a line of work that allows the incorporation of planning short work cycles on equips quickly with operational autonomy on the basis of demand and respecting the accreditation requirements and flexibility to ensure adequate performance as the intercomparison of results from the different units analytics, analytical quality and turnaround times. Between 2012 and 2014, a process of analysis and improvement was applied to circuits, a 5 s system, transportation of samples, inventory of reactive and samples, motion of personal and samples, reductions of waiting and delays, overproduction, over processing, and defects of results and reports. At last it seems necessary to apply the Agile methodology to adapt to the evolving necessities in time and the different origins of the samples. It’s have used modular systems where the modules of this study are programmed with immunoassay techniques and it has reduced the operative modules depending on the required activity, ensuring the goals of turnaround times, analytic quality, service, health care continuity, and keeping up with the ISO 15189 accreditation requirements. The results of applying the concept of Lean-Agile to a modular system allows us to reduce the associated costs to the seasonal variation of the health care demand and to adapt the system to the changes on the pattern of analytic demand. The savings obtained are two laboratory technicians for a month and those derived from deactivating a complete modular section consisting of three analysts. Average turnaround time (TAT) of 99.5% from the analyzed parameters has been kept equal to the one obtained in common conditions with a p < 0.01. The laboratory has maintained the quality goals measured in analytical variability. Prior to that, it most objectified the inter-comparability of the results among the used channels. Full article

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Open AccessArticle

Application of Linear Quadratic Gaussian and Coefficient Diagram Techniques to Distributed Load Frequency Control of Power Systems

by Tarek Hassan Mohamed, Ahmed A. Zaki Diab and Mahmoud M. Hussein

Appl. Sci. 2015, 5(4), 1603-1615; https://doi.org/10.3390/app5041603 - 4 Dec 2015

Cited by 10 | Viewed by 5282

Abstract

This paper presented both the linear quadratic Gaussian technique (LQG) and the coefficient diagram method (CDM) as load frequency controllers in a multi-area power system to deal with the problem of variations in system parameters and load demand change. The full states of [...] Read more.

This paper presented both the linear quadratic Gaussian technique (LQG) and the coefficient diagram method (CDM) as load frequency controllers in a multi-area power system to deal with the problem of variations in system parameters and load demand change. The full states of the system including the area frequency deviation have been estimated using the Kalman filter technique. The efficiency of the proposed control method has been checked using a digital simulation. Simulation results indicated that, with the proposed CDM + LQG technique, the system is robust in the face of parameter uncertainties and load disturbances. A comparison between the proposed technique and other schemes is carried out, confirming the superiority of the proposed CDM + LQG technique. Full article

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Open AccessArticle

Diode-Pumped High Energy and High Average Power All-Solid-State Picosecond Amplifier Systems

by Jiaxing Liu, Wei Wang, Zhaohua Wang, Zhiguo Lv, Zhiyuan Zhang and Zhiyi Wei

Appl. Sci. 2015, 5(4), 1590-1602; https://doi.org/10.3390/app5041590 - 4 Dec 2015

Cited by 20 | Viewed by 7537

Abstract

We present our research on the high energy picosecond laser operating at a repetition rate of 1 kHz and the high average power picosecond laser running at 100 kHz based on bulk Nd-doped crystals. With diode-pumped solid state (DPSS) hybrid amplifiers consisting of [...] Read more.

We present our research on the high energy picosecond laser operating at a repetition rate of 1 kHz and the high average power picosecond laser running at 100 kHz based on bulk Nd-doped crystals. With diode-pumped solid state (DPSS) hybrid amplifiers consisting of a picosecond oscillator, a regenerative amplifier, end-pumped single-pass amplifiers, and a side-pumped amplifier, an output energy of 64.8 mJ at a repetition rate of 1 kHz was achieved. An average power of 37.5 W at a repetition rate of 100 kHz pumped by continuous wave laser diodes was obtained. Compact, stable and high power DPSS laser amplifier systems with good beam qualities are excellent picosecond sources for high power optical parametric chirped pulse amplification (OPCPA) and high-efficiency laser processing. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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2629 KiB

Open AccessReview

Irregular Homogeneity Domains in Ternary Intermetallic Systems

by Jean-Marc Joubert, Mohamed Andasmas and Jean-Claude Crivello

Appl. Sci. 2015, 5(4), 1570-1589; https://doi.org/10.3390/app5041570 - 4 Dec 2015

Cited by 10 | Viewed by 5687

Abstract

Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds AB_x, AC_x and BC_x with the same crystal structure. This causes irregular shapes of the [...] Read more.

Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds AB_x, AC_x and BC_x with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe–Nb–Zr, Hf–Mo–Re, Hf–Re–W, Mo–Re–Zr, Re–W–Zr, Cr–Mn–Si, Cr–Mo–Re, and Mo–Ni–Re, and involving the topologically close-packed Laves, χ and σ phases. These systems have been studied using ternary isothermal section determination, DFT calculations, site occupancy measurement using joint X-ray, and neutron diffraction Rietveld refinement. Conclusions are drawn concerning this phenomenon. The paper also reports new experimental or calculated data on Co–Cr–Re and Fe–Nb–Zr systems. Full article

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Local Effects on Lung Parenchyma Using a 600 µm Bare Fiber with the Diode-Pumped Nd:YAG Laser LIMAX^® 120

by Peter Rexin, Detlef Bartsch and Andreas Kirschbaum

Appl. Sci. 2015, 5(4), 1560-1569; https://doi.org/10.3390/app5041560 - 3 Dec 2015

Cited by 2 | Viewed by 5225

Abstract

Lung metastases are frequently removed with an Nd:YAG laser. The aim is to perform a non-anatomic resection of all intraoperatively palpable lung metastases completely in order to preserve the largest possible amount of healthy lung parenchyma. The surgeon can either work with a [...] Read more.

Lung metastases are frequently removed with an Nd:YAG laser. The aim is to perform a non-anatomic resection of all intraoperatively palpable lung metastases completely in order to preserve the largest possible amount of healthy lung parenchyma. The surgeon can either work with a focusing handpiece or use a laser fiber of the so-called bare fiber with direct contact to the lung parenchyma. We currently use a 600 µm bare fiber for applications involving the lung parenchyma. Precise data on the local effect of the laser fiber on the lung parenchyma are not available, especially with regard to an increase in the laser energy. We want to study this question within the scope of an experimental model in pig lungs by means of systematic and reproducible tests. The lung lobes were removed from animals recently slaughtered in the abattoir and taken to the laboratory immediately, where the lobes were stored such that the surface of the lungs was parallel to the floor. A 600 µm bare fiber was attached to a mounting bracket vertically above the lung surface at a distance of either 0, 5, or 10 mm. This mounting bracket was in turn connected to a hydraulic feed motor. The feed motor is capable of moving the bare fiber forward across the lungs consistently at three different speeds (5 mm/s, 10 mm/s, or 20 mm/s). The bare fiber itself was connected to the diode-pumped Nd: YAG Laser LIMAX^® 120 (Gebrüder Martin GmbH & Co KG, Tuttlingen, Germany). We carried out the tests using three different laser powers: 20 W, 60 W, and 120 W. The lung lesions caused by the laser in each of the lungs were resected and sent in for histological analysis. The exact size of the vaporization and coagulation zone was measured using the HE sections, and the respective mean values (with standard deviations) were ascertained. For all laser powers, the extent of the vaporization was greatest with a motion speed of 5 mm/s for the respective laser power: 756.4 ± 1.2 µm (20 W), 1411.0 ± 2.3 µm (60 W) and 2126.0 ± 1.4 µm (120 W). At the same time, the extent of the coagulation zone decreased with a consistent speed: 221.8 ± 2.9 µm (20 W), 324.9 ± 1.8 µm (60 W), and 450.5 ± 1.8 µm (120 W). With a consistent laser energy and increasing speed, we also saw a decrease in the size of the vaporization and of the coagulation zone. The same applies for an increasing distance of the bare fiber to the lung surface. The coagulation effect is the dominant effect here. At an operating speed of 5 mm/s and a maximum laser energy of 120, the 600 µm bare fiber exerts a maximum effect. With an increasing distance of the tip of the bare fiber to the lung surface, the coagulation effect is dominant. The effect of the laser decreases with increasing operating speeds. Full article

(This article belongs to the Special Issue Casting Light on Cancer Therapy)

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Open AccessArticle

Synthesis and Physical and Chemical Properties of Hypergolic Chemicals such as N,N,N-Trimethylhydrazinium and 1-Ethyl-4-Methyl-1,2,4-Triazolium Salts

by Young-Seok Kim, Gi-Hyuk Son, Tae-Kyung Na and Seong-Ho Choi

Appl. Sci. 2015, 5(4), 1547-1559; https://doi.org/10.3390/app5041547 - 2 Dec 2015

Cited by 10 | Viewed by 5259

Abstract

Hypergolic chemicals N,N,N-trimethylhydrazinium iodide, [TMH]⁺[I]⁻, and 1-ethyl-4-methyl-1,2,4-triazolium iodide, [EMT]⁺[I]⁻ were firstly synthesized by nucleophilic substitution (S_N2). The successful synthesis of hypergolic chemicals [TMH]⁺[I]⁻ and [EMT]⁺ [...] Read more.

Hypergolic chemicals N,N,N-trimethylhydrazinium iodide, [TMH]⁺[I]⁻, and 1-ethyl-4-methyl-1,2,4-triazolium iodide, [EMT]⁺[I]⁻ were firstly synthesized by nucleophilic substitution (S_N2). The successful synthesis of hypergolic chemicals [TMH]⁺[I]⁻ and [EMT]⁺[I]⁻ was confirmed by IR and ¹H-NMR spectroscopy and, GC-mass spectrometry. Subsequently the hypergolic chemicals [TMH]⁺[X]⁻ (X = CN⁻, N₃⁻, NO₃⁻, NO₂⁻, ClO₄⁻, AlCl₄⁻) were prepared via an ion exchange reaction from [TMH]⁺[I]⁻ and [EMT]⁺[I]⁻, respectively. After that, a mixture of hypergolic chemicals was prepared by dissolving the synthesized hypergolic chemicals in 2-hydroxyethylhydrazine (HOCH₂CH₂NHNH₂). The physical and chemical properties of the mixture such as decomposition temperature (T_d), density (d), viscosity (η), and decomposition energy (ΔH_d) was then evaluated to determine suitability for use as liquid rocket fuels. The ignition delay (ID) time of the mixture of hypergolic chemicals with [TMH]⁺[N₃]⁻ and [TMH]⁺[CN]⁻ using H₂O₂ as an oxidizer was determined as 55.6 ms and 97.4 ms; respectively. The ID time of the mixture of hypergolic chemicals with [EMT]⁺[N₃]⁻; [EMT]⁺[CN]⁻; [EMT]⁺[AlCl₄]⁻; and [EMT]⁺[I]⁻ using H₂O₂ as an oxidizer was also determined as 18.0 ms; 32.6 ms; 27.6 ms; and 7.96 ms; respectively. The synthesized mixture of hypergolic chemicals could thus be used as a rocket propellant liquid fuel. Full article

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Open AccessArticle

A Local Texture-Based Superpixel Feature Coding for Saliency Detection Combined with Global Saliency

by Bingfei Nan, Zhichun Mu, Long Chen and Jian Cheng

Appl. Sci. 2015, 5(4), 1528-1546; https://doi.org/10.3390/app5041528 - 2 Dec 2015

Cited by 4 | Viewed by 6122

Abstract

Because saliency can be used as the prior knowledge of image content, saliency detection has been an active research area in image segmentation, object detection, image semantic understanding and other relevant image-based applications. In the case of saliency detection from cluster scenes, the [...] Read more.

Because saliency can be used as the prior knowledge of image content, saliency detection has been an active research area in image segmentation, object detection, image semantic understanding and other relevant image-based applications. In the case of saliency detection from cluster scenes, the salient object/region detected needs to not only be distinguished clearly from the background, but, preferably, to also be informative in terms of complete contour and local texture details to facilitate the successive processing. In this paper, a Local Texture-based Region Sparse Histogram (LTRSH) model is proposed for saliency detection from cluster scenes. This model uses a combination of local texture patterns and color distribution as well as contour information to encode the superpixels to characterize the local feature of image for region contrast computing. Combining the region contrast as computed with the global saliency probability, a full-resolution salient map, in which the salient object/region detected adheres more closely to its inherent feature, is obtained on the bases of the corresponding high-level saliency spatial distribution as well as on the pixel-level saliency enhancement. Quantitative comparisons with five state-of-the-art saliency detection methods on benchmark datasets are carried out, and the comparative results show that the method we propose improves the detection performance in terms of corresponding measurements. Full article

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Privacy-Preserving Smart Metering with Authentication in a Smart Grid

by Jun Beom Hur, Dong Young Koo and Young Joo Shin

Appl. Sci. 2015, 5(4), 1503-1527; https://doi.org/10.3390/app5041503 - 1 Dec 2015

Cited by 20 | Viewed by 5920

Abstract

The traditional security objectives of smart grids have been availability, integrity, and confidentiality. However, as the grids incorporate smart metering and load management, user and corporate privacy is increasingly becoming an issue in smart grid networks. Although transmitting current power consumption levels to [...] Read more.

The traditional security objectives of smart grids have been availability, integrity, and confidentiality. However, as the grids incorporate smart metering and load management, user and corporate privacy is increasingly becoming an issue in smart grid networks. Although transmitting current power consumption levels to the supplier or utility from each smart meter at short intervals has an advantage for the electricity supplier’s planning and management purposes, it threatens user privacy by disclosing fine-grained consumption data and usage behavior to utility providers. In this study, we propose a distributed incremental data aggregation scheme where all smart meters on an aggregation path are involved in routing the data from the source meter to the collection unit. User privacy is preserved by symmetric homomorphic encryption, which allows smart meters to participate in the aggregation without seeing any intermediate or final result. Aggregated data is further integrated with an aggregate signature to achieve data integrity and smart meter authentication in such a way that dishonest or fake smart meters cannot falsify data en route. Only the collection unit can obtain the aggregated data and verify its integrity while the individual plain data are not exposed to the collection unit. Therefore, user privacy and security are improved for the smart metering in a smart grid network. Full article

(This article belongs to the Special Issue Smart Grid: Convergence and Interoperability)

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Appl. Sci., Volume 5, Issue 4 (December 2015) – 83 articles , Pages 637-2008

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