Applied Sciences

344 KiB

Open AccessArticle

A Novel MPPT Control Method of Thermoelectric Power Generation with Single Sensor

by Hiroaki Yamada, Koji Kimura, Tsuyoshi Hanamoto, Toshihiko Ishiyama, Tadashi Sakaguchi and Tsuyoshi Takahashi

Appl. Sci. 2013, 3(2), 545-558; https://doi.org/10.3390/app3020545 - 29 Apr 2013

Cited by 15 | Viewed by 8616

Abstract

This paper proposes a novel Maximum Power Point Tracking (MPPT) control method of thermoelectric power generation for the constant load. This paper reveals the characteristics and the internal resistance of thermoelectric power module (TM). Analyzing the thermoelectric power generation system with boost chopper [...] Read more.

This paper proposes a novel Maximum Power Point Tracking (MPPT) control method of thermoelectric power generation for the constant load. This paper reveals the characteristics and the internal resistance of thermoelectric power module (TM). Analyzing the thermoelectric power generation system with boost chopper by state space averaging method, the output voltage and current of TM are estimated by with only single current sensor. The proposed method can seek without calculating the output power of TM in this proposed method. The basic principle of the proposed MPPT control method is discussed, and then confirmed by digital computer simulation using PSIM. Simulation results demonstrate that the output voltage can track the maximum power point voltage by the proposed MPPT control method. The generated power of the TM is 0.36 W when the temperature difference is 35 °C. This is well accorded with the V-P characteristics. Full article

(This article belongs to the Special Issue Renewable Energy)

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1051 KiB

Open AccessReview

What We Can Learn about Ultrashort Pulses by Linear Optical Methods

by Adam Borzsonyi, Attila P. Kovacs and Karoly Osvay

Appl. Sci. 2013, 3(2), 515-544; https://doi.org/10.3390/app3020515 - 26 Apr 2013

Cited by 33 | Viewed by 13250

Abstract

Spatiotemporal compression of ultrashort pulses is one of the key issues of chirped pulse amplification (CPA), the most common method to achieve high intensity laser beams. Successful shaping of the temporal envelope and recombination of the spectral components of the broadband [...] Read more.

Spatiotemporal compression of ultrashort pulses is one of the key issues of chirped pulse amplification (CPA), the most common method to achieve high intensity laser beams. Successful shaping of the temporal envelope and recombination of the spectral components of the broadband pulses need careful alignment of the stretcher-compressor stages. Pulse parameters are required to be measured at the target as well. Several diagnostic techniques have been developed so far for the characterization of ultrashort pulses. Some of these methods utilize nonlinear optical processes, while others based on purely linear optics, in most cases, combined with spectrally resolving device. The goal of this work is to provide a review on the capabilities and limitations of the latter category of the ultrafast diagnostical methods. We feel that the importance of these powerful, easy-to-align, high-precision techniques needs to be emphasized, since their use could gradually improve the efficiency of different CPA systems. We give a general description on the background of spectrally resolved linear interferometry and demonstrate various schematic experimental layouts for the detection of material dispersion, angular dispersion and carrier-envelope phase drift. Precision estimations and discussion of potential applications are also provided. Full article

(This article belongs to the Special Issue Ultraintense Ultrashort Pulse Lasers)

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Graphical abstract

705 KiB

Open AccessArticle

Photopolymerization Reactions: On the Way to a Green and Sustainable Chemistry

by Mohamad Ali Tehfe, Fanny Louradour, Jacques Lalevée and Jean-Pierre Fouassier

Appl. Sci. 2013, 3(2), 490-514; https://doi.org/10.3390/app3020490 - 24 Apr 2013

Cited by 170 | Viewed by 13644

Abstract

The present paper reviews some aspects concerned with the development of green technologies in the photopolymerization area: use of visible light sources (Xe and Hg-Xe lamps, diode lasers), soft irradiation conditions (household lamps: halogen lamp, fluorescence bulbs, LED bulbs), sunlight exposure, development of [...] Read more.

The present paper reviews some aspects concerned with the development of green technologies in the photopolymerization area: use of visible light sources (Xe and Hg-Xe lamps, diode lasers), soft irradiation conditions (household lamps: halogen lamp, fluorescence bulbs, LED bulbs), sunlight exposure, development of very efficient photoinitiating systems and use of renewable monomers. The drawbacks/breakthroughs encountered when going on the way of a greener approach are discussed. Examples of recent achievements are presented. Full article

(This article belongs to the Special Issue Greener and Sustainable Chemistry)

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465 KiB

Open AccessArticle

Effect of the Presence of Nonionic Surfactant Brij35 on the Mobility of Metribuzin in Soil

by Eman M. ElSayed and Shiv O. Prasher

Appl. Sci. 2013, 3(2), 469-489; https://doi.org/10.3390/app3020469 - 24 Apr 2013

Cited by 5 | Viewed by 7537

Abstract

Given the water scarcity becoming endemic to a large portion of the globe, arid region irrigation has resorted to the use of treated, partially treated, or even untreated wastewaters. Such waters contain a number of pollutants, including surfactants. Applied to agricultural lands, these [...] Read more.

Given the water scarcity becoming endemic to a large portion of the globe, arid region irrigation has resorted to the use of treated, partially treated, or even untreated wastewaters. Such waters contain a number of pollutants, including surfactants. Applied to agricultural lands, these surfactants could affect the fate and transport of other chemicals in the soil, particularly pesticides. A field lysimeter study was undertaken to investigate the effect of nonionic surfactant, Brij35, on the in-soil fate and transport of a commonly used herbicide, metribuzin [4-amino-6-tert-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one]. Nine PVC lysimeters, 1.0 m long × 0.45 m diameter, were packed with a sandy soil to a bulk density of 1.35 mg m⁻³. Antibiotic-free cattle manure was applied (10 mg ha⁻¹) at the surface of the lysimeters. Metribuzin was then applied to the soil surface of all lysimeters at a rate of 1.00 kg a.i. ha⁻¹. Each of three aqueous Brij35 solutions, 0, 0.5 and 5 mg L⁻¹ (i.e., “good”, “poor” and “very poor” quality irrigation water) were each applied to the lysimeters in triplicate. Analysis for metribuzin residues in samples of both soil and leachate, collected over a 90-day period, showed the surfactant Brij35 to have increased the mobility of metribuzin in soil, indicating that continued use of poor quality water could influence pesticide transport in agricultural soils, and increase the risk of groundwater contamination. Full article

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215 KiB

Open AccessArticle

Ultrasonics Promoted Synthesis of 5-(Pyrazol-4-yl)-4,5-Dihydropyrazoles Derivatives

by Jorge Trilleras, Efraín Polo, Jairo Quiroga, Justo Cobo and Manuel Nogueras

Appl. Sci. 2013, 3(2), 457-468; https://doi.org/10.3390/app3020457 - 16 Apr 2013

Cited by 14 | Viewed by 7012

Abstract

A series of new 1,3-diaryl-5-(1-phenyl-3-methyl-5-chloropyrazol-4-yl)-4,5-dihydropyrazole derivatives have been synthesized under sonication conditions in ethanol or methanol/glacial acetic acid mixture (5/1 ratio) with two equivalents of hydrazines and seven kinds of chalcone-like heteroanalogues obtained from 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde. The structures were established on the [...] Read more.

A series of new 1,3-diaryl-5-(1-phenyl-3-methyl-5-chloropyrazol-4-yl)-4,5-dihydropyrazole derivatives have been synthesized under sonication conditions in ethanol or methanol/glacial acetic acid mixture (5/1 ratio) with two equivalents of hydrazines and seven kinds of chalcone-like heteroanalogues obtained from 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde. The structures were established on the basis of NMR, IR, MS and element analysis. This method provides several advantages over current reaction methodologies, including a simple work-up procedure, shorter reaction times (2–20 min) and good yields (65%–80%). Full article

(This article belongs to the Special Issue Greener and Sustainable Chemistry)

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511 KiB

Open AccessArticle

Control of a Stand-Alone Variable Speed Wind Energy Supply System

by Mahmoud M. Hussein, Tomonobu Senjyu, Mohamed Orabi, Mohamed A. A. Wahab and Mohamed M. Hamada

Appl. Sci. 2013, 3(2), 437-456; https://doi.org/10.3390/app3020437 - 11 Apr 2013

Cited by 62 | Viewed by 16275

Abstract

This paper presents a simple control strategy for the operation of a variable speed stand-alone wind turbine with a permanent magnet synchronous generator (PMSG). The PMSG is connected to a three phase resistive load through a switch mode rectifier and a voltage source [...] Read more.

This paper presents a simple control strategy for the operation of a variable speed stand-alone wind turbine with a permanent magnet synchronous generator (PMSG). The PMSG is connected to a three phase resistive load through a switch mode rectifier and a voltage source inverter. Control of the generator side converter is used to achieve maximum power extraction from the available wind power. Control of the DC-DC bidirectional buck-boost converter, which is connected between batteries bank and DC-link voltage, is used to maintain the DC-link voltage at a constant value. It is also used to make the batteries bank stores the surplus of wind energy and supplies this energy to the load during a wind power shortage. The load side voltage source inverter uses a relatively complex vector control scheme to control the output load voltage in terms of amplitude and frequency. The control strategy works under wind speed variation as well as with variable load. Extensive simulation results have been performed using MATLAB/SIMULINK. Full article

(This article belongs to the Special Issue Renewable Energy)

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3053 KiB

Open AccessArticle

Power Collection from Wave Energy Farms

by Jonas Sjolte, Gaute Tjensvoll and Marta Molinas

Appl. Sci. 2013, 3(2), 420-436; https://doi.org/10.3390/app3020420 - 2 Apr 2013

Cited by 45 | Viewed by 9169

Abstract

Most Wave Energy Converters (WECs) produce highly distorted power due to thereciprocal motion induced by ocean waves. Some WEC systems have integrated energystorage that overcomes this limitation, but add significant expenses to an already costlysystem. As an alternative approach, this article investigates the [...] Read more.

Most Wave Energy Converters (WECs) produce highly distorted power due to thereciprocal motion induced by ocean waves. Some WEC systems have integrated energystorage that overcomes this limitation, but add significant expenses to an already costlysystem. As an alternative approach, this article investigates the direct export option thatrelies on aggregate smoothing among several WECs. By optimizing the positioning of theWEC devices with respect to the incoming waves, fluctuations may be mutually canceledout between the devices. This work is based on Fred. Olsen’s WEC system Lifesaver, anda WEC farm consisting of 48 devices is designed in detail and simulated. The major costdriver for the electrical export system is the required oversize factor necessary for transferof the average power output. Due to the low power quality, this number can be as high as20 at the entry point of the electrical system, and it is thus crucial to quickly improve thepower quality so that the downstream power system is efficiently utilized. The simulationsundertaken in this work indicate that a high quality power output can be achieved at the farmlevel, but that a significant oversize factor will be required in the intermediate power systemwithin the farm. Full article

(This article belongs to the Special Issue Renewable Energy)

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528 KiB

Open AccessReview

A Review of the Role of Amphiphiles in Biomass to Ethanol Conversion

by Anahita Dehkhoda Eckard, Kasiviswanathan Muthukumarappan and William Gibbons

Appl. Sci. 2013, 3(2), 396-419; https://doi.org/10.3390/app3020396 - 2 Apr 2013

Cited by 39 | Viewed by 8788

Abstract

One of the concerns for economical production of ethanol from biomass is the large volume and high cost of the cellulolytic enzymes used to convert biomass into fermentable sugars. The presence of acetyl groups in hemicellulose and lignin in plant cell walls reduces [...] Read more.

One of the concerns for economical production of ethanol from biomass is the large volume and high cost of the cellulolytic enzymes used to convert biomass into fermentable sugars. The presence of acetyl groups in hemicellulose and lignin in plant cell walls reduces accessibility of biomass to the enzymes and makes conversion a slow process. In addition to low enzyme accessibility, a rapid deactivation of cellulases during biomass hydrolysis can be another factor contributing to the low sugar recovery. As of now, the economical reduction in lignin content of the biomass is considered a bottleneck, and raises issues for several reasons. The presence of lignin in biomass reduces the swelling of cellulose fibrils and accessibility of enzyme to carbohydrate polymers. It also causes an irreversible adsorption of the cellulolytic enzymes that prevents effective enzyme activity and recycling. Amphiphiles, such as surfactants and proteins have been found to improve enzyme activity by several mechanisms of action that are not yet fully understood. Reduction in irreversible adsorption of enzyme to non-specific sites, reduction in viscosity of liquid and surface tension and consequently reduced contact of enzyme with air-liquid interface, and modifications in biomass chemical structure are some of the benefits derived from surface active molecules. Application of some of these amphiphiles could potentially reduce the capital and operating costs of bioethanol production by reducing fermentation time and the amount of enzyme used for saccharification of biomass. In this review article, the benefit of applying amphiphiles at various stages of ethanol production (i.e., pretreatment, hydrolysis and hydrolysis-fermentation) is reviewed and the proposed mechanisms of actions are described. Full article

(This article belongs to the Special Issue Renewable Energy)

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1710 KiB

Open AccessReview

Cutting-Edge High-Power Ultrafast Thin Disk Oscillators

by Clara J. Saraceno, Cinia Schriber, Florian Emaury, Oliver H. Heckl, Cyrill R. E. Baer, Martin Hoffmann, Kolja Beil, Christian Kränkel, Matthias Golling, Thomas Südmeyer and Ursula Keller

Appl. Sci. 2013, 3(2), 355-395; https://doi.org/10.3390/app3020355 - 2 Apr 2013

Cited by 33 | Viewed by 10738

Abstract

A growing number of applications in science and industry are currently pushing the development of ultrafast laser technologies that enable high average powers. SESAM modelocked thin disk lasers (TDLs) currently achieve higher pulse energies and average powers than any other ultrafast oscillator technology, [...] Read more.

A growing number of applications in science and industry are currently pushing the development of ultrafast laser technologies that enable high average powers. SESAM modelocked thin disk lasers (TDLs) currently achieve higher pulse energies and average powers than any other ultrafast oscillator technology, making them excellent candidates in this goal. Recently, 275 W of average power with a pulse duration of 583 fs were demonstrated, which represents the highest average power so far demonstrated from an ultrafast oscillator. In terms of pulse energy, TDLs reach more than 40 μJ pulses directly from the oscillator. In addition, another major milestone was recently achieved, with the demonstration of a TDL with nearly bandwidth-limited 96-fs long pulses. The progress achieved in terms of pulse duration of such sources enabled the first measurement of the carrier-envelope offset frequency of a modelocked TDL, which is the first key step towards full stabilization of such a source. We will present the key elements that enabled these latest results, as well as an outlook towards the next scaling steps in average power, pulse energy and pulse duration of such sources. These cutting-edge sources will enable exciting new applications, and open the door to further extending the current performance milestones. Full article

(This article belongs to the Special Issue Ultraintense Ultrashort Pulse Lasers)

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488 KiB

Open AccessArticle

Modelling the Contribution of Domestic Heat Pumps to Delivering UK Energy Policy Objectives

by David Braun and Paul Rowley

Appl. Sci. 2013, 3(2), 338-354; https://doi.org/10.3390/app3020338 - 28 Mar 2013

Cited by 3 | Viewed by 7195

Abstract

The UK Government has ambitious targets for CO₂ emissions reductions, particularly for the domestic housing stock. One technology that is expected to contribute significantly is heat pumps, both air and ground source. However, recent field trial results suggest that heat pumps in [...] Read more.

The UK Government has ambitious targets for CO₂ emissions reductions, particularly for the domestic housing stock. One technology that is expected to contribute significantly is heat pumps, both air and ground source. However, recent field trial results suggest that heat pumps in the UK are not delivering to performance expectations. This paper looks at the implications of these results for the UK housing stock’s future CO₂ emissions. The English Housing Condition Survey dataset is used as the basis for a Monte Carlo simulation in order to model CO₂ emissions and energy consumption for the whole of English housing stock out to 2050. The results suggest that, given the current UK electricity grid CO₂emission factor, in the short term poor heat pump performance could lead to a rise in emissions where natural gas boilers are displaced. In the longer term, heat pumps can realise emissions reductions when installed at high penetration levels when combined with a grid decarbonisation strategy. Until grid decarbonisation occurs, an alternative phased strategy is proposed that includes phased replacement of resistive electric heating, first in households in fuel poverty and then the remainder of properties with this heating type. Following this phased strategy, real emissions savings are possible along with a potential reduction in fuel poverty. Full article

(This article belongs to the Special Issue Renewable Energy)

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257 KiB

Open AccessArticle

A Comparative Analysis of Energy Costs of Photovoltaic, Solar Thermal, and Wind Electricity Generation Technologies

by Michael Dale

Appl. Sci. 2013, 3(2), 325-337; https://doi.org/10.3390/app3020325 - 25 Mar 2013

Cited by 85 | Viewed by 16190

Abstract

Global installed capacity of renewable energy technologies is growing rapidly. The ability of renewable technologies to enable a rapid transition to a low carbon energy system is highly dependent on the energy that must be “consumed” during their life-cycle. This paper presents the [...] Read more.

Global installed capacity of renewable energy technologies is growing rapidly. The ability of renewable technologies to enable a rapid transition to a low carbon energy system is highly dependent on the energy that must be “consumed” during their life-cycle. This paper presents the results of meta-analyses of life-cycle assessments (LCA) of energy costs of three renewable technologies: solar photovoltaic (PV), concentrating solar power (CSP), and wind. The paper presents these findings as energetic analogies with financial cost parameters for assessing energy technologies: overnight capital cost, operating costs and levelized cost of electricity (LCOE). The findings suggest that wind energy has the lowest energy costs, followed by CSP and then PV. Full article

(This article belongs to the Special Issue Renewable Energy)

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Appl. Sci., Volume 3, Issue 2 (June 2013) – 11 articles , Pages 325-558

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