1,326 research outputs found
Stability issues of dye solar cells
No full textThe thesis discusses dye solar cells (DSCs) which are emerging as a potential candidate for many applications. The goal of the work was to find more stable and higher performing materials for flexible DSCs, improve understanding of the effects on the DSC stability, and to develop experimental methods that give improved resolution of the degradation mechanisms.
First an intensive critical literature review was done to highlight the important degradation mechanisms in DSCs. It was concluded that techniques giving chemical information are needed to understand the degradation reactions and their effect on electrical performance. It would be advantageous to have methods that enable monitoring chemical changes in operating DSCs, or periodically over their lifetime during accelerated ageing tests. Here the focus was on new and advanced in-situ methods that allow continuous study of the aging of the cells. In this regard, optical techniques such as Raman spectroscopy, newly introduced image processing method and recently introduced segmented cell method were employed to bridge the link between the chemical changes in the DSCs and the standard PV measurement methods. Here for instance the image processing was demonstrated to study the bleaching of electrolyte under ultraviolet and visible light at 85°C. The results obtained with the image processing method and the standard electrical measurements were in agreement and showed that the bleaching of electrolyte was initiated by TiO2 and slowed down by the presence of the dye.
For the roll-to-roll production of DSCs cheap, flexible and stable substrates are required. In this work, a series of metals i.e. StS 304, StS 321, StS 316, StS 316L and Ti were successfully stabilized at the CE of a DSC by using a sputtered Pt catalyst layer that doubled also as a corrosion blocking layer. This work was an important step forward towards stable flexible DSCs.
Finally, the degradation due to the manufacturing step related to the electrolyte filling in the DSC was studied. With the help of recently introduced segmented cell method, it was found the nanoporous film of TiO2 was acting as filter for some of the commonly used electrolyte additives i.e. tBP and NMBI. This resulted in spatial performance variation in the DSC which lead to significant losses in the overall performance (here up to 35 % losses in the up-scaling) and thus it has important implications for large area DSCs
Wireless control for life-critical actions
No full textHealthcare is one of the application areas of real‐time wireless communications and control. With the development of communication and control technologies, there is a potential to transfer not only observed data but also skills over wireless links. Telesurgery and remote diagnosis are examples of transferring skills with real‐time wireless control. Such applications include observing patients as well as diagnosing them remotely, which is the transfer of skills of doctor to the remote location. In this chapter, we discuss real‐time wireless control for life‐critical actions. In particular, we introduce the basics of wireless control systems and discuss the fundamental design capabilities needed to realize real‐time wireless control, with primary emphasis given to communication‐control co‐design. The goal is to provide integrated solutions for life‐critical actions in healthcare. A co‐design system model is proposed and explained in detail. Simulation results are discussed and benefits of co‐design are depicted in terms of both control and communication performance
A review on solid oxide fuel cell durability : Latest progress, mechanisms, and study tools
No full textFunding Information: The authors are thankful to Academy of Finland (Grant No. 13329016, 13322738) for the financial support. Dr. Asghar also thanks the Hubei Overseas Talent 100 program. Funding Information: The authors are thankful to Academy of Finland (Grant No. 13329016 , 13322738 ) for the financial support. Dr. Asghar also thanks the Hubei Overseas Talent 100 program . Publisher Copyright: © 2022 The AuthorsThe commercial breakthrough of solid oxide fuel cells (SOFCs) is still hampered by degradation related issues. Most SOFCs that perform well do not possess good stability. To achieve a targeted degradation rate of 0.2%/1000 h important to a durable SOFC device, it is vital to identify the sources of degradation. So far, the longest stable performance was given by F1002-97, a short stack from Forschungszentrum Jülich GmbH, which reached 93,000 h of operation at 700 °C under 0.5 A cm−2 constant current density with a degradation rate of 0.5%/1000 h. In this review, we discuss the most detrimental degradation mechanisms for the core components of the SOFC, mainly poisoning, microstructural deformations, and strains. Electrochemical, chemical, and structural characterization tools for quantifying degradation mechanisms are also presented. The following section addresses the most recent progress in SOFC durability and the associated methods for analyzing degradation. These techniques include different doping techniques (including Mo, Nb, Co, Ce, Ta, Sn, etc.), surface modifications (e.g.infiltration, exsolution techniques, protective coatings), and interface engineering. Finally, the factors that inhibit the enhancement of SOFC durability are briefly discussed, such as inadequate knowledge of the degradation process and limitations in the material choices.Peer reviewe
Development and characterization of highly stable electrode inks for low-temperature ceramic fuel cells
No full textFunding Information: The authors are thankful to Academy of Finland (Grant No. 13329016 , 13322738 ) for the financial support. Dr. Asghar also thanks the Hubei Overseas Talent 100 program.Inkjet printing is a potential contactless and mask-free additive manufacturing approach for solid oxide fuel cells. Here, a highly stable cathode ink using La0.6Sr0.4Co0.2Fe0.8O3 was developed and characterized with particle size analysis, viscosity, surface tension, density, and thermal analysis. Both fresh and 6-months stored inks showed excellent jetability behavior with a Z number of 2.77 and 3.45, respectively. The ink was successfully inkjet-printed on a (LiNaK)2CO3-Gd:CeO2 porous electrolyte substrate to fabricate a symmetric cell. The electrochemical impedance spectroscopy measurements showed that at 550 °C the inkjet printing lowered the ohmic resistance to one-third (from 1.05 Ω cm2 to 0.37 Ω cm2) and the mass diffusion resistance by 4.25 times (from 6.09 Ω cm2 to 1.43 Ω cm2) as compared to drop-casted cell by creating a hierarchical porous structure and increasing reaction sites. Successful inkjet printing of the functional electrode material opens up a new avenue for the fabrication of the low-temperature ceramic fuel cells.Peer reviewe
Yksi- ja kolmikerroksisten nanokomposiittipolttokennojen analysointi
No full textThe public defense on 3rd April 2020 at 12:00 will be organized via remote technology.
Link: https://aalto.zoom.us/j/729014568
Zoom Quick Guide: https://www.aalto.fi/en/services/zoom-quick-guideFuel cells (FCs) convert the chemical energy of fuel directly to electricity. FCs are potential canditates for clean electricity sources in the future, provided that the main challenges halting their commercialization can be solved. Several different FC subtypes exist. This Thesis is focused on ceramic nanocomposite FCs (CNFCs) and single-layer FCs (SLFCs). Both of these FCs operate at intermediate temperatures, at around 500-600 °C.
CNFC utilizes the traditional three-layer structure: anode, electrolyte, and cathode. The key component is the electrolyte, that consists of a composite of a solid oxide and a salt, here doped ceria and alkali carbonate mixture respectively. This composite electrolyte allows an efficient multi-ion conduction, reducing the ohmic losses in the cell. Excellent power densities, exceeding 1 W per square centimeter, were achieved with two different CNFCs in this Thesis.
SLFC is a ground-breaking innovation where all FC functions are compressed into one single layer, consisting of a mixture of a semiconductor (here lithium nicke zinc oxide or copper iron oxide) and an ionic conductor (here doped ceria or doped ceria – alkali carbonate mixture). The SLFC desing allows to elimintate the challenges originating from the three-layer structure and to simplify the manufacturing procedure. In this Thesis, the working principle and performance-affecting factors of SLFCs were studied. The key findings include that the proton is dominating over the oxygen-ion in ionic conduction with the studied SLFC configuration and that applying the composite ionic conductor of CNFC to SLFC improves vastly the cell performance.
Since both CNFCs and SLFCs are complex nanoscale structures, studying the microstructure of these devices with electron microscopy and X-ray spectroscopy are identified as crucial procedures to understand the macroscopic output. Systematic studies combined with modern microscopic methods are suggested as a pathway to push both SLFCs and CNFCs towards commercialization.Polttokennot muuttavat polttoaineen kemiallisen energian suoraan sähköksi. Polttokennot ovat potentiaalisia ehdokkaita tulevaisuuden puhtaaseen sähköntuotantoon, mikäli niiden kaupallistamista rajoittavat keskeiset haasteet saadaan ratkaistua. Polttokennoja on useita eri tyyppejä. Tämä väitöskirja käsittelee keraamisia nanokomposiittipolttokennoja (CNFC) ja yksikomponenttipolttokennoja (SLFC). Molemmat näistä operoivat keskialueen lämpötiloissa, noin 500-600 celsiusasteessa.
CNFC:t hyödyntävät perinteistä kolmikerroksista rakennetta: niissä on anodi, elektrolyytti ja katodi. Avainkomponentti on elektrolyytti, joka koostuu kiinteän oksidin ja suolan, tässä väitöskirjassa seostetun ceriumoksidin ja alkalikarbonaattiseoksen, muodostamasta komposiitista. Tällainen komposiittielektrolyytti mahdollistaa tehokaan moni-ionijohtavuuden, mikä vähentää kennon ohmisia häviöitä. Erinomaiset tehotiheydet, yli 1 W neliösenttimetriä kohti, saavutettiin kahdella eri CNFC:llä tässä väitöskirjassa.
SLFC on uraauurtava innovaatio missä kaikki polttokennotoiminnot on tiivistetty yhteen kerrokseen, joka koostuu puolijohteen (tässä väitöskirjassa litium-nikkeli-sinkkioksidi tai kupari-rautaoksidi) ja ionijohteen (tässä väitöskirjassa seostettu ceriumoksidi tai seostettu ceriumoksidi – alkalikarbonaattisekoitus). SLFC:n rakenne eliminoi haasteet, jotka johtuvat kolmikerrosrakenteesta ja mahdollistaa valmistusmenetelmien yksinkertaistamisen. Tässä väitöskirjassa tutkittiin SLFC:n toimintaperiaatetta ja suorituskykyyn vaikuttavia tekijöitä. Avaintuloksiin sisältyy protonin dominointi happi-ionin suhteen ionijohtavuudessa tutkituissa SLFC-konfiguraatioissa sekä se, että CNFC:n komposiitti-ionijohteen soveltaminen SLFC:hen paransi huomattavasti suorituskykyä.
Koska sekä CNFC että SLFC ovat monimutkaisia nanotason rakenteita, niiden mikrorakenteen tutkiminen elektronimikroskopialla ja röntgensädespektroskopialla tunnistettiin kriittiseksi menetelmiksi makroskooppisen toiminnan ymmärtämiseksi. Systemaattisia tutkimuksia yhdistettynä moderneihin mikroskooppisiin metodeihin ehdotetaan keinoksi edistää sekä CNFC:n että SLFC:n kaupallistamista
The Life of Hedonism from the Perspective of Al-Tabari and Sayyid Muhammad Rashid Rida (Comparative Study of Tafsir Surah Ali Imran: 14)
No full textThe Qur'an not only tells us about prohibitions and commands, but also talks about the problems of the lives of previous people. Among them are illustrated by the human lifestyle that prioritizes pleasure and physical luxury. Based on the hedonistic lifestyle, it certainly has 'ibrah that can be learned if an in-depth study of the life of hedonism is carried out. The author wants to examine the life of hedonism from the perspective of al-Tabari and Sayyid Muhammad Rasyid Rida. This paper uses a qualitative approach that is classified into library research with library materials, especially Jami' al-Bayan fi Ta'wil Ayi al-Qur'an and Tafsir al-Manar and uses comparative data analysis. The conclusion in this paper is that the life of hedonism according to al-Tabari and Sayyid Muhammad Rasyid Rida is an excessive human lifestyle and indulges in lust in reaching the pleasures of the world. The similarities and differences according to these two mufassirs are almost the same in interpreting the life of hedonism in surah Ali Imran verse 14 that Allah SWT makes beautiful in human views of the pleasures of the world, namely women, children, large assets of gold and silver, selected horses, livestock and rice fields. Sayyid Muhammad Rasyid Rida besides agreeing with Imam al-Tabari, he added that human love for the beauty and pleasure of the world is not only specific to the Jews, but is general
Developing domain-specific mashup tools for end users
No full textThe recent emergence of mashup tools has refueled research on end user development, i.e., on enabling end users without programming skills to compose own applications. Yet, similar to what happened with analogous promises in web service composition and business process management, research has mostly focused on technology and, as a consequence, has failed its objective. Plain technology (e.g., SOAP/WSDL web services) or simple modeling languages (e.g., Yahoo! Pipes) don't convey enough meaning to non-programmers. We propose a domain-specific approach to mashups that "speaks the language of the user", i.e., that is aware of the terminology, concepts, rules, and conventions (the domain) the user is comfortable with. We show what developing a domain-specific mashup tool means, which role the mashup meta-model and the domain model play and how these can be merged into a domain-specific mashup meta-model. We apply the approach implementing a mashup tool for the research evaluation domain. Our user study confirms that domain-specific mashup tools indeed lower the entry barrier to mashup development. Copyright is held by the author/owner(s)
Interface engineering of bi-layer semiconductor SrCoSnO3-δ-CeO2-δ heterojunction electrolyte for boosting the electrochemical performance of low-temperature ceramic fuel cell
No full textFunding Information: This work was supported Southeast University (SEU) PROJET # 3203002003A1 and National Natural Science Foundation of China (NSFC) under the grant # 51772080 and 11604088 . Dr. Asghar thanks the Hubei overseas Talent 100 program (as a distinguished professor at Hubei University) and Academy of Finland (Grant No. 13329016, 13322738) for their support. Publisher Copyright: © 2021 The Author(s)A comparative study is performed to investigate the electrochemical performance of the low-temperature ceramic fuel cells (CFCs) utilizing two different novel electrolytes. First, a perovskite semiconductor SrCo0.3Sn0.7O3-δ was used as an electrolyte in CFCs due to its modest ionic conductivity (0.1 S/cm) and demonstrated an acceptable power density of 360 mW/cm2 at 520 °C. The performance of the cell was primarily limited due to the moderate ionic transport in the electrolyte. In order to improve the ionic conductivity, a new strategy of using a novel bi-layer electrolyte concept consist of SrCo0.3Sn0.7O3-δ and CeO2-δ in CFCs. These bi-layers of two electrolytes have successfully established heterojunction which considerably improved the ionic conductivity (0.2 S/cm) and enhance the open-circuit voltage of the cell from 0.98 V to 1.001 V. Moreover, the CFCs utilizing bi-layer electrolyte have produced a remarkable power density of 672 mW/cm2 at 520 °C. This enhancement of ionic conduction, power density and blockage of electron conduction in the bi-layer electrolyte was studied via band alignment mechanism based on proposed p-n heterojunction. Our work presents a promising methodology for developing advanced low-temperature CFC electrolytes.Peer reviewe
Tailoring triple charge conduction in BaCo0.2Fe0.1Ce0.2Tm0.1Zr0.3Y0.1O3−δ semiconductor electrolyte for boosting solid oxide fuel cell performance
No full textFunding Information: This work was supported by the National Natural Science Foundation of China (NSFC) under the (grant # 11674085 and 51772080 ) and National Laboratory of solid-state Microstructures, Nanjing University for project support is also acknowledged. Dr. Asghar thanks the Hubei overseas Talent 100 program (as a distinguished professor at Hubei University) and Academy of Finland (Grant No. 13329016 and 13322738 ) for their support. Muhammad Akbar helped in the Scanning electron microscope (SEM) images assistance. Publisher Copyright: © 2021 The Author(s) Copyright: Copyright 2021 Elsevier B.V., All rights reserved.Introducing multiple-ionic transport through a semiconductor-electrolyte is a promising approach to realize the low-temperature operation of SOFCs. Herein, we designed and synthesized a single-phase Ce-doped BaCo0.2Fe0.3-xTm0.1Zr0.3Y0.1O3-δ semiconductor-electrolyte possessing triple-charge (H+/O2−/e−) conduction ability. Two different compositions are synthesized: BaCo0.2Fe0.3-xCexTm0.1Zr0.3Y0.1O3-δ [x = 0.1–0.2]. The 20% doped Ce composition exhibits an outstanding oxide-ion and protonic conductivity of 0.193 S cm−1 and 0.09 S cm−1 at 530 °C and the fuel cell utilizing BaCo0.2Fe0.2Ce0.2Tm0.1Zr0.3Y0.1O3-δ as an electrolyte yields an excellent power density of 873 mW cm−2 at 530 °C. Moreover, the fuel cell performed reasonably well (383 mW cm−2) even at a low temperature of 380 °C. Furthermore, the 10% Ce-doped utilized in fuel cell device illustrates lower performance (661 mW cm−2 at 530 °C and 260 mW cm−2 at 380 °C). Successful doping of Ce supports the formation of oxygen-vacancies at the B-site of perovskite and adjusting the ratio of Fe in the compositions. Moreover, the presence of Tm also assist in the creation of oxygen vacancies. Furthermore, the boosting of electrochemical performance and ionic conductivity of applied materials are enlightened by tuning the energy-band structure via employing the UPS and UV–Vis. The physical characterizations and verification of dual-ions (H+/O2−) in the semiconductor materials are performed via different electrochemical, spectroscopic, and microscopic techniques. A systematic study revealed triple charge conduction in this promising material, which helps in boosting the electrochemical performance of the LT-SOFC.Peer reviewe
Retraction Note: Refining Parkinson’s neurological disorder identification through deep transfer learning (Neural Computing and Applications, (2020), 32, 3, (839-854), 10.1007/s00521-019-04069-0)
No full textThe Editor-in-Chief and the publisher have retracted this article. The article was submitted to be part of a guest-edited issue. An investigation by the publisher found a number of articles, including this one, with a number of concerns, including but not limited to compromised editorial handling and peer review process, inappropriate or irrelevant references or not being in scope of the journal or guest-edited issue. Based on the investigation's findings the Editor-in-Chief therefore no longer has confidence in the results and conclusions of this article. The authors Imran Razzak and Saeeda Naz disagree with this retraction. The author Muhammad Imran has not responded to correspondence regarding this retraction. The Publisher has not been able to obtain a current email address for the authors Amina Naseer, Monail Rani, and Guandong Xu
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