Journal articles on the topic 'Electrical energy systems, n.e.c'
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Adigun, Oluwole Daniel, Emmanuel Ricohermoso, Ayodele Abeeb Daniyan, Lasisi Ejibunu Umoru, and Emanuel Ionescu. "Structure and Electrical Properties of Carbon-Rich Polymer derived Silicon Carbonitride (SiCN)." Ceramics 5, no. 4 (October 3, 2022): 690–705. http://dx.doi.org/10.3390/ceramics5040050.
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This article reports on the structure and electronic properties of carbon-rich polysilazane polymer-derived silicon carbonitride (C/SiCN) corresponding to pyrolysis temperatures between 1100 and 1600 °C in an argon atmosphere. Raman spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM) and Hall measurements were used to support the structural and electronic properties characterization of the prepared C/SiCN nanocomposites. A structural analysis using Raman spectroscopy showed the evolution of sp2 hybridized carbon phase that resulted from the growth in the lateral crystallite size (La), average continuous graphene length including tortuosity (Leq) and inter-defects distance (LD) with an increase in pyrolysis temperature. The prepared C/SiCN monoliths showed a record high room temperature (RT) electrical conductivity of 9.6 S/cm for the sample prepared at 1600 °C. The electronic properties of the nanocomposites determined using Hall measurement revealed an anomalous change in the predominant charge carriers from n-type in the samples pyrolyzed at 1100 °C to predominantly p-type in the samples prepared at 1400 and 1600 °C. According to this outcome, tailor-made carbon-rich SiCN polymer-derived ceramics could be developed to produce n-type and p-type semiconductors for development of the next generation of electronic systems for applications in extreme temperature environments.
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Alexandrov, Peter, Xueqing Li, Matt O'Grady, and John Hostetler. "Analog and Logic High Temperature Integrated Circuits based on SiC JFETs." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2014, HITEC (January 1, 2014): 000061–65. http://dx.doi.org/10.4071/hitec-tp12.
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Harsh environment applications such as electrical actuation on military and commercial aircraft, advanced engine controls, downhole energy exploration, propulsion systems of hybrid and all electric vehicles, and space exploration require sensor interfaces, control circuits, and power systems with electronics capable of operating at high temperatures. Wide band-gap materials such as SiC can be used to build devices with high operating temperatures due to their fundamental material properties. This paper presents initial results on developing basic analog and logic integrated circuits based on SiC JFET technology. Analog and logic integrated circuits were built using enhancement vertical channel lateral JFET transistors, metal film resistors and lateral p-n diodes. The analog circuits built include different types of operational amplifiers. The logic circuits include NOT, NAND, AND, NOR and OR gates. Transistors and integrated circuits were packaged in ceramic DIP packages and tested at temperatures up to 500 °C. The tested JFETs show proper operation up to the maximum tested temperature of 500 °C. The operational amplifiers remained functional at temperatures up to 430 °C. Basic logic circuits showed proper operation up to the maximum tested temperature of 500 °C.
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Wang, Guoming. "Efficient quantum algorithms for analyzing large sparse electrical networks." Quantum Information and Computation 17, no. 11&12 (September 2017): 987–1026. http://dx.doi.org/10.26421/qic17.11-12-5.
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Analyzing large sparse electrical networks is a fundamental task in physics, electrical engineering and computer science. We propose two classes of quantum algorithms for this task. The first class is based on solving linear systems, and the second class is based on using quantum walks. These algorithms compute various electrical quantities, including voltages, currents, dissipated powers and effective resistances, in time poly(d, c,log(N), 1/λ, 1/e), where N is the number of vertices in the network, d is the maximum unweighted degree of the vertices, c is the ratio of largest to smallest edge resistance, λ is the spectral gap of the normalized Laplacian of the network, and e is the accuracy. Furthermore, we show that the polynomial dependence on 1/λ is necessary. This implies that our algorithms are optimal up to polynomial factors and cannot be significantly improved.
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Ngernchuklin, Piyalak, Arjin Boonruang, Saengdoen Daungdaw, and Nestchanok Yongpraderm. "Comparison of Milling Techniques to Figure of Merit of 0.98PZT-0.02BYF Piezoelectric Ceramic Energy Harvester." Key Engineering Materials 690 (May 2016): 218–23. http://dx.doi.org/10.4028/www.scientific.net/kem.690.218.
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Nowadays, the concept of harvesting energy from the environment, for example, thermal, wind, sun, vibration and human activities is much of interest. PZT is one of the materials which show an ability to harness vibration energy and then change to electrical energy. Therefore, the PZT (Pb(Zr0.53Ti0.47)O3) doped with 0.02 mol% BYF (Bi(Y0.7Fe0.3)O3) piezoelectric ceramics has been studied to improve the figure of merit (d33*g33). The PZT and BYF powder systems were prepared by solid state reaction with calcination temperature of 800 and 850 °C for 2 h, respectively. XRD results showed that both powders exhibited pure perovskite phase for PZT and single phase of BYF without pyrochlore phase. Then, the two calcined powders (PZT and BYF) were mixed according to the composition of 0.02 mol% BYF doped PZT by two different milling techniques called conventional ball-milling (CBM) and high energy ball-milling (HBM) for 10 h. The result showed that average particle size obtain from HBM was 1 µm which was smaller than from CBM shown up to a few microns in bimodal mode. The PZT-BYF-HBM ceramics showed higher physical and electrical properties but lower K value. Thus promoting to higher g33 which was equal to 36.89 * 10-3(Vm/N) and FOM was 11,632*10-15(m2/N), while PZT-BYF-CBM had g33 of 26.86* 10-3(Vm/N) and FOM at 8,016*10-15(m2/N), respectively.
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Satpute, Jitendra, and John Rajan. "Analysis of energy, exergy, environmental and economics (4E) on PV-thermal collector system." Thermal Science, no. 00 (2022): 10. http://dx.doi.org/10.2298/tsci210905010s.
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In this paper, a novel thermal absorber based photovoltaic thermal system is presented. The thermal absorber is attached at the rear surface of photovoltaic, and water is re-circulated to extract heat. The outdoor experimentations are performed at Pune, India (18.7611?N, 73.5572?) on clear sky day, and water temperatures, surface temperature, radiation and flow rate are measured to analyze techno-economical performance at different operating conditions. The surface temperature of the photovoltaic module plummeted from 54.65?C to 47.9?C with the incorporation of a thermal absorber with flipside water cooling at a ranging flow rate of 0.03 to 0.06 kg/sec. The result shows an average enhancement of 4.2 % in the electrical power output of the photovoltaic thermal system. The maximum thermal and electrical efficiencies were 47.82 % and 9.88 %, respectively, at 0.06 kg/sec. The exergy efficiency was found in the range of 9.85-14.30%. Based on the experimental evaluation, uncertainty analysis was performed. The results revealed that the annual CO2 mitigation for photovoltaic and photovoltaic thermal system was 225.46 kg/annum and 464.8 kg/annum, while simple payback periods were 4.53 years 3.03 years, respectively. The analysis offers an efficient estimate of experimental features of photovoltaic and photovoltaic thermal systems from an energy-exergy, environmental and cost-benefit standpoint.
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Abu Khalla, Shada, Salman Abdalla, Arunchander Asokan, and Matthew Suss. "Desalination Fuel Cells: Producing Clean Energy and Water." ECS Meeting Abstracts MA2022-01, no. 45 (July 7, 2022): 1939. http://dx.doi.org/10.1149/ma2022-01451939mtgabs.
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Desalination has evolved into a viable alternative to fresh water supply, increasing water availability and decreasing scarcity1. Reverse osmosis (RO) is the most-widely used technology today for desalination, and requires significant electrical energy investment, about 4 kWh/m3 of treated water, when desalinating sea water2. In contrast to such conventional desalination systems which utilize energy, we will here dicsuss desalination fuel cells (DFCs), an emerging electrochemical desalination technology proposed by our group3. DFC’s utilize hydrogen gas to simultaneously desalinate water and produce electricity from a single cell. Thus, water can be desalinated without any external electrical supply required. The desalination fuel cell is based on continuous energy conversion from chemical to electrical, and thus is not cyclic as with capacitive deionization4. As with an ED cell, our cell consists of one anion and one cation exchange membrane which sandwich a desalination channel fed with feedwater. Unlike an ED cell, on the opposite side of the anion exchange membrane is a hydrogen anode and anolyte, while an oxygen cathode and catholyte are placed opposite to the CEM. During operation, the reductant present in the anolyte (hydrogen) and oxidant present in the catholyte (oxygen) react spontaneously at the anode and cathode surfaces, respectively, providing an electric current between the anode and cathode which can be delivered to a load. The half-reactions also give rise to a spontaneous ionic current through the cell, which drives ion removal from the desalination channel (Figures a,b). The cell was characterized by running it in two modes, with either near-neutral pH in all channels (H2|O2) (Figure a) or with a pH-gradient mode (H2+B|O2+A) (Figure b), which allowed for deep insight into cell performance and detailed characterizations (Figures c-f)5. The results show that our prototype can desalinate water effectively while generating electricity, it was also found that operation in H2+B|O2+A mode enabled improved DFC performance, higher OCV, and produced electricity of up to 10 kWh/m3 (Figure g)5. A detailed voltage breakdown, elucidating key sources of loss in the cell was also demonstrated adding quasi-reference electrodes in all flow channels of the cell. It was shown that voltage loss across ion exchange membranes was generally insignificant, but the cathode is generally the component associated with the largest voltage loss, largely due to Nernstian losses exacerbated by likely chloride poisoning of the cathode catalyst (Figure i)6. Chloride poisoning was studied in-situ, by flowing different catholytes through the cell, and ex-situ using an RRDE. We further synthesized and optimized custom, non-precious metal-based Fe/N/C catalyst for desalination fuel cell cathodes, and showed nearly equal catalytic performance to that of the Pt/C commercial cathode (Figure h)7. References: Kummu, M. et al. The world’s road to water scarcity: Shortage and stress in the 20th century and pathways towards sustainability. Rep. 6, 1–16 (2016). Malaeb, L. & Ayoub, G. M. Reverse osmosis technology for water treatment: State of the art review. Desalination 267, 1–8 (2011). Atlas, I., Abu Khalla, S. & Suss, M. E. Thermodynamic Energy Efficiency of Electrochemical Systems Performing Simultaneous Water Desalination and Electricity Generation. Electrochem. Soc. 167, 134517 (2020). Porada, S., Zhao, R., Van Der Wal, A., Presser, V. & Biesheuvel, P. M. Review on the science and technology of water desalination by capacitive deionization. Mater. Sci. 58, 1388–1442 (2013). Abu Khalla, S., Atlas, I. & Suss, M. E. Desalination fuel cells with high thermodynamic energy efficiency. Environmental Science & Technology. Accepted. Abdalla, S., Abu Khalla, S. & Suss, M. E. Voltage loss breakdown in desalination fuel cells. Electrochemistry Communications 107136 (2021). Asokan, A., Abu-Khalla, S., Abdalla, S. & Suss., M. E. Chloride-tolerant, inexpensive Fe/N/C catalysts exceed platinum catalysts for desalination fuel cell cathodes. ACS Applied Energy Materials. Submitted. Figure 1
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Jaita, Pharatree, Narumon Lertcumfu, and Gobwute Rujijanagul. "Temperature Dependence on Ferroelectric, Energy Storage Density, and Electric Field-Induced Strain Response of Lead-Free Bi0.485(Na0.388K0.097)Ba0.021Sr0.009TiO3 Ceramics." Integrated Ferroelectrics 201, no. 1 (September 2, 2019): 142–54. http://dx.doi.org/10.1080/10584587.2019.1668698.
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In this research, Bi0.485(Na0.388K0.097)Ba0.021Sr0.009TiO3 or BNKBSrT ceramic sintered at various temperatures from 1100 °C to 1150 °C were investigated. The optimum density (5.80 g/cm3), mechanical (HK = 5.3 GPa, HV = 4.1 GPa, E = 62 GPa, and KIC = 1.35 MPa m1/2), dielectric (εr = 1525, tanδ = 0.0566), piezoelectric (d33 = 172 pC/N, g33 = 12 × 10−3 Vm/N), electric field-induced strain (Smax = 0.32%, d*33 = Smax/Emax = 640 pm/V, Q33 = 0.0340 m4/C2), and energy storage (W = 0.55 J/cm3, η = 67.2% @ 150 °C) were obtained for the ceramic sintered at 1125 °C.
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MORALES-SÁNCHEZ, E., J. GONZÁLEZ-HERNÁNDEZ, R. RAMÍREZ-BON, F. ESPINOZA-BELTRÁN, Y. VOROBIEV, A. MORALES-ACEVEDO, PETRO GORLEY, Z. KOVALYUK, and PAUL HORLEY. "CdTe and Si SOLAR CELL PERFORMANCE COMPARISON IN A NEW SYSTEM FOR SOLAR ENERGY CONVERSION AND STORAGE." Modern Physics Letters B 15, no. 17n19 (August 20, 2001): 597–600. http://dx.doi.org/10.1142/s0217984901002087.
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A new system for the effective conversion and storage of solar energy using CdTe and Si based photovoltaic solar cells and the Li- Bi 2 Se 3 rechargable batteries was created and studied. PV Solar Cells with the different types of structure and barrier were studied (Shottky. MIS with thin insulating layer, and p-n junction), employing low-temperature and high-temperature technological cycles. The influence of the technological details upon the electrical parameters as well as the efficiency and stability of their performance were analyzed, and also the condition for improving the efficiency were found. In particular, it was established that Zn-doping of CdTe and the Al alloying to Si at 800°C have a profound effect upon the PV cell characteristics. The influence of the recombination in different parts of the cell upon the cell's efficiency and the recombination dependence upon the technological features were investigated. A comparison of the performance and fabrication cost of the new systems for solar energy conversion and storage with others using conventional cells and batteries is made. It is shown that newly developed systems could provide a global efficiency close to that for traditional ones, with simpler and cheaper technology. With some modifications of the technology, we expect to get even higher efficiencies and a wider system operation temperature range. The possibilities are discussed for the creation of a hybrid energy conversion system on the basis of our cells and batteries, with an overall efficiency of transformation of solar-to-electric energy around 40%.
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Laverde, Jennifer, Nataly C. Rosero-Navarro, Akira Miura, Robison Buitrago-Sierra, Kiyoharu Tadanaga, and Diana López. "Impact of Sulfur Infiltration Time and Its Content in an N-doped Mesoporous Carbon for Application in Li-S Batteries." Batteries 8, no. 6 (June 17, 2022): 58. http://dx.doi.org/10.3390/batteries8060058.
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Li-S batteries are ideal candidates to replace current lithium-ion batteries as next-generation energy storage systems thanks to their high specific capacity and theoretical energy density. Composite electrodes based on carbon microstructures are often used as a host for sulfur. However, sulfur lixiviation, insoluble species formation, and how to maximize the sulfur-carbon contact in looking for improved electrochemical performance are still major challenges. In this study, a nitrogen doped mesoporous carbon is used as a host for sulfur. The S/C composite electrodes are prepared by sulfur melting-diffusion process at 155 °C. The effect of the sulfur melting-diffusion time [sulfur infiltration time] (1–24 h) and sulfur content (10–70%) is investigated by using XRD, SEM, TEM and TGA analyses and correlated with the electrochemical performance in Li-S cells. S/C composite electrode with homogeneous sulfur distribution can be reached with 6 h of sulfur melting-diffusion and 10 wt.% of sulfur content. Li-S cell with this composite shows a high use of sulfur and sufficient electronic conductivity achieving an initial discharge capacity of 983 mA h g−1 and Coulombic efficiency of 99% after 100 cycles.
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Ishii, I., R. McLaren, A. P. Hitchcock, K. D. Jordan, Y. Choi, and M. B. Robin. "The σ* molecular orbitals of perfluoroalkanes as studied by inner-shell electron energy loss and electron transmission spectroscopies." Canadian Journal of Chemistry 66, no. 8 (August 1, 1988): 2104–21. http://dx.doi.org/10.1139/v88-336.
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Absolute oscillator strength spectra in the C 1s (280–340 eV) and F 1s (680–740 eV) regions of the perfluoro-n-alkanes from C2 to C6 and perfluorocycloalkanes from C3 to C6 have been determined from inner-shell electron energy loss spectra recorded under electric-dipole scattering conditions. The spectral features are interpreted in terms of spatially localized transitions terminating at orbitals of predominantly σ*(C—F) and σ*(C—C) character. When compared to the spectra of the perfluoro-n-alkanes, both the C 1s and F 1s spectra of the perfluorocycloalkanes exhibit additional low-lying bands which are assigned to transitions terminating at σ*(C—C) orbitals which are shifted to low energy by the combination of the strain of cyclization and the inductive effect of the fluorination. The electron transmission spectra of selected perfluorocycloalkanes (which provide information on their anion states) show as well that the electron affinities of the cyclic systems are substantially lower than those of the corresponding perfluoro-n-alkanes, again as a result of a low-lying σ* orbital in the cyclic species. Quantum chemical calculations of the alkane and perfluoroalkane ground-state orbital structures support the experimental results. The localized character of the inner-shell excitations, indicated by the constancy of both term values and oscillator strengths with increasing chain length, contrasts with the more delocalized character of the states accessed in ultraviolet excitation or negative ion formation.
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Gablech, Imrich, Jaroslav Klempa, Jan Pekárek, Petr Vyroubal, Jan Hrabina, Miroslava Holá, Jan Kunz, Jan Brodský, and Pavel Neužil. "Simple and Efficient AlN-Based Piezoelectric Energy Harvesters." Micromachines 11, no. 2 (January 28, 2020): 143. http://dx.doi.org/10.3390/mi11020143.
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In this work, we demonstrate the simple fabrication process of AlN-based piezoelectric energy harvesters (PEH), which are made of cantilevers consisting of a multilayer ion beam-assisted deposition. The preferentially (001) orientated AlN thin films possess exceptionally high piezoelectric coefficients d33 of (7.33 ± 0.08) pC∙N−1. The fabrication of PEH was completed using just three lithography steps, conventional silicon substrate with full control of the cantilever thickness, in addition to the thickness of the proof mass. As the AlN deposition was conducted at a temperature of ≈330 °C, the process can be implemented into standard complementary metal oxide semiconductor (CMOS) technology, as well as the CMOS wafer post-processing. The PEH cantilever deflection and efficiency were characterized using both laser interferometry, and a vibration shaker, respectively. This technology could become a core feature for future CMOS-based energy harvesters.
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Sukach, A. V. "SiCN films: preparation, properties and practical application (review)." Optoelektronìka ta napìvprovìdnikova tehnìka 55 (December 31, 2020): 83–108. http://dx.doi.org/10.15407/iopt.2020.55.083.
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Si-CN films exhibit high mechanical and optoelectronic properties such as photoconductivity, photoluminescence, variable energy gap in the range of 1.37-5.2 eV, high mechanical and thermal strength, low thermal expansion, which allows them to be used in semiconductor devices. and in microelectronic mechanical systems. They are obtained by chemical deposition methods, and to activate the reaction using thermal heating, plasma or ultraviolet radiation, and by physical methods of deposition at relatively low temperatures by magnetron sputtering. The structure of the films can vary from microcrystalline to amorphous, the main influence being the deposition temperature. Chemical bonding in films is carried out mainly due to the interaction of Si-N, Si-C, C-C, C-N. Despite a significant amount of experimental work to study the properties of Si-C-N films, there are virtually no studies of films deposited by plasma chemical methods using hexamethyldisilazane as the main precursor. The review analyzes the influence of the main parameters of plasma chemical deposition, such as substrate temperature, reagent flow rate, high-frequency discharge power and displacement on the substrate on the physical properties of the films. It is shown that the main mechanism of transport of charge carriers in the investigated films is the space charge limited current. Based on electrical measurements, a number of band parameters as well as parameters of deep traps in a-SiCN films were estimated for the first time.
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Samoylov, A. V. "OPTIMIZATION OF THE DESIGN OF POLYMER QUARTER SUPERACHROMATIC WAVEPLATES." Optoelektronìka ta napìvprovìdnikova tehnìka 55 (December 31, 2020): 151–55. http://dx.doi.org/10.15407/iopt.2020.55.151.
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Si-CN films exhibit high mechanical and optoelectronic properties such as photoconductivity, photoluminescence, variable energy gap in the range of 1.37-5.2 eV, high mechanical and thermal strength, low thermal expansion, which allows them to be used in semiconductor devices. and in microelectronic mechanical systems. They are obtained by chemical deposition methods, and to activate the reaction using thermal heating, plasma or ultraviolet radiation, and by physical methods of deposition at relatively low temperatures by magnetron sputtering. The structure of the films can vary from microcrystalline to amorphous, the main influence being the deposition temperature. Chemical bonding in films is carried out mainly due to the interaction of Si-N, Si-C, C-C, C-N. Despite a significant amount of experimental work to study the properties of Si-C-N films, there are virtually no studies of films deposited by plasma chemical methods using hexamethyldisilazane as the main precursor. The review analyzes the influence of the main parameters of plasma chemical deposition, such as substrate temperature, reagent flow rate, high-frequency discharge power and displacement on the substrate on the physical properties of the films. It is shown that the main mechanism of transport of charge carriers in the investigated films is the space charge limited current. Based on electrical measurements, a number of band parameters as well as parameters of deep traps in a-SiCN films were estimated for the first time.
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Gorbunov, A. V., O. G. Devoino, V. A. Gorbunova, O. K. Yatskevitch, and V. A. Koval. "Thermodynamic Estimation of the Parameters for the C–H–O–N–Me-Systems as Operating Fluid Simulants for New Processes of Powder Thermal Spraying and Spheroidizing." Science & Technique 20, no. 5 (October 7, 2021): 390–98. http://dx.doi.org/10.21122/2227-1031-2021-20-5-390-398.
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Over the past few years, a group of new processes was developed for high-temperature, including plasma electric arc spraying (at ambient pressure) and spheroidizing of some ceramic and metal powder materials with the use of gaseous hydrocarbons in the heat carriers as well as with feeding of organic additions into a high-temperature jet, in particular, polymeric ones, to control porosity of sprayed metallic functional coatings. The paper considers the possibility to modify such technological processes by introducing solid fuel additions of a polymer type into the operating fluid of an apparatus for gasthermal (plasma or other) treatment, which provides melting of metal or oxide powders. For this, with the help of thermodynamic analysis, the processes have been evaluated at temperatures (300–3000) K for the set of such reacting five component systems as C–H–O–N–Me (at ambient pressure 0.101 MPa) with five variants of Ме – aluminum, titanium, chrome, copper, nickel. This makes it possible to consider these systems as simulants for potential technologies for the treatment of oxide powders (Al2O3, TiO2, Cr2O3) as well as metallic ones (Cu, Ni and their alloys). In order to obtain high exothermic contribution to the heating of powders, the combination “air + polymeric addition (polyethylene) of LDPE grade” was chosen as mixed heat carrier (operating fluid) for the basic version of simulated process. During the analysis of equilibria for the considered multicomponent systems (17 variants), a set of following parameters has been used to characterize the energy intensity of the target powder heating process: the equivalence ratio for reacting mixture and its adiabatic temperature; the energy efficiency of material heating with and without taking into account the effect of fuel addition; specific energy consumption for the powder melting; autothermicity degree of the process during the combined heating (electrothermal heating by the arc of plasma torch and heat flux from the “air + solid fuel additions” mixture) of refractory powders. As a result of the assessment, the preferred (from thermodynamic standpoint) regimes of the considered processes have been found and the possibility to realize an energy-efficient heating of these oxide and metal materials (without oxidation of the latter to CuOx, NiO) with a reduced part of the electric channel of energy transfer, resulted from the carrying out of appreciable effect of the fuel-initiated mechanism of heating in the analyzed C–H–O–N–Mesystems, has been shown in the paper.
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Yazvinskaya, Nataliya N., Nikolay E. Galushkin, Dmitriy V. Ruslyakov, and Dmitriy N. Galushkin. "Generalized Peukert Equations Use for Finding the Remaining Capacity of Lithium-Ion Cells of Any Format." Energies 14, no. 16 (August 15, 2021): 5009. http://dx.doi.org/10.3390/en14165009.
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In many studies, for predicting the remaining capacity of batteries belonging to different electrochemical systems, various analytical models based on the Peukert equation are used. This paper evaluates the advantages and disadvantages of the most famous generalized Peukert equations. For lithium-ion batteries, the Peukert equation cannot be used for estimation of their remaining capacity over the entire range of discharge currents. However, this paper proves that the generalized Peukert equations enable estimation of the capacity released by lithium-ion batteries with high accuracy. Special attention is paid to two generalized Peukert equations: C = Cm/(1 + (i/i0)n) and C = Cmerfc((i-i0)/n))/erfc(-i0/n). It is shown that they correspond to the experimental data the best.
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Zhang, Wenting, Caorui Zhang, Junmin Wu, Fei Yang, Yunlai An, Fangjing Hu, and Ji Fan. "Low Temperature Hydrophilic SiC Wafer Level Direct Bonding for Ultrahigh-Voltage Device Applications." Micromachines 12, no. 12 (December 17, 2021): 1575. http://dx.doi.org/10.3390/mi12121575.
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SiC direct bonding using O2 plasma activation is investigated in this work. SiC substrate and n− SiC epitaxy growth layer are activated with an optimized duration of 60s and power of the oxygen ion beam source at 20 W. After O2 plasma activation, both the SiC substrate and n− SiC epitaxy growth layer present a sufficient hydrophilic surface for bonding. The two 4-inch wafers are prebonded at room temperature followed by an annealing process in an atmospheric N2 ambient for 3 h at 300 °C. The scanning results obtained by C-mode scanning acoustic microscopy (C-SAM) shows a high bonding uniformity. The bonding strength of 1473 mJ/m2 is achieved. The bonding mechanisms are investigated through interface analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). Oxygen is found between the two interfaces, which indicates Si–O and C–O are formed at the bonding interface. However, a C-rich area is also detected at the bonding interface, which reveals the formation of C-C bonds in the activated SiC surface layer. These results show the potential of low cost and efficient surface activation method for SiC direct bonding for ultrahigh-voltage devices applications.
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Almehmadi, Fahad Awjah, H. F. Elattar, A. Fouda, Saeed Alqaed, Jawed Mustafa, Mathkar A. Alharthi, and H. A. Refaey. "Energy Performance Assessment of a Novel Solar Poly-Generation System Using Various ORC Working Fluids in Residential Buildings." Energies 15, no. 21 (November 6, 2022): 8286. http://dx.doi.org/10.3390/en15218286.
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Poly-generation systems are an exciting new technology that provide an alternative to separating existing energy production methods in buildings. A poly-generation system enables the efficient simultaneous production of heating, cooling, fresh water, and electricity, resulting in many technological, economic, energy recovery, and environmental advantages. This study numerically investigates three proposed novel solar-driven poly-generation systems (BS, IS-I, and IS-II) integrated with organic Rankine cycle (ORC), humidification-dehumidification desalination system (HDH), and desiccant cooling system (DCS) with different heat recovery system arrangements. The suggested systems supply residential structures with energy, space conditioning, domestic heating, and fresh water. The effects of system operating circumstances on productivity and performance characteristics and several organic working fluid types (n-octane, R245fa, R113, isopentane, and toluene) on optimum system performance have been investigated. The results show that (i) the average enhancement percentage of TGOR using integrated poly-generation systems over the separated ones is 68.5%, 68.5%, and 95.5% for BS, IS-I, and IS-II systems, respectively; (ii) when comparing the three systems, the IS-I system outperforms the other systems (BS & IS-II); and (iii) the maximum values of W•net, m•fresh, Q•cooling, and Q•heating, obtained for different proposed systems using n-octane are 102 kW (all systems), 214.7 kg/h (IS-II), 29.94 kW (IS-II), and 225.6 kW (IS-I); (iv) R113 has the highest TGOR of 0.6924 (IS-I) compared to other organic fluids. (v) The improvements in Wnet•, mfresh•, Qcooling• and Qheating• with using toluene instead of R113 at tf1 = 40 °C are 177.5%, 105.8%, 389.25%, and 79%, respectively.
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Owhoso, Fiki V., and David G. Kwabi. "Effect of Covalent Modification on Proton-Coupled Electron Transfer at Quinone-Functionalized Carbon Electrodes." ECS Meeting Abstracts MA2022-02, no. 57 (October 9, 2022): 2171. http://dx.doi.org/10.1149/ma2022-02572171mtgabs.
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Electrodes functionalized with molecularly well-defined reactive/catalytic species have become attractive for promoting a wide variety of electrochemical energy conversion processes or systems, such as electrocatalytic CO2 and O2 reduction, as well as metal-sulfur and redox-flow batteries.1-3 Critical to the performance of these electrodes is the interaction between the electric field, and the molecular species at the electrical double layer. Nevertheless, elucidating the potential/electric field experienced at the functionalized interface is challenging. We show in this work that the acid-base thermochemical (i.e. Pourbaix) behavior of molecular quinones can vary depending on their mode of covalent attachment to a carbon electrode and ionic strength of the electrolyte, in a manner that sheds light on the experienced interfacial electric field. This work can inform strategies for effective pH modulation at electrified interfaces in ways that can enhance the electrocatalytic processes and systems mentioned above, and enable newer applications such as pH-swing-based electrochemical CO2 capture using appropriately chemically modified electrodes.4 References 1 Ren, G. et al. Porous Core–Shell Fe3C Embedded N-doped Carbon Nanofibers as an Effective Electrocatalysts for Oxygen Reduction Reaction. ACS Applied Materials & Interfaces 8, 4118-4125, doi:10.1021/acsami.5b11786 (2016). 2 Zhang, S., Fan, Q., Xia, R. & Meyer, T. J. CO2 Reduction: From Homogeneous to Heterogeneous Electrocatalysis. Accounts of Chemical Research 53, 255-264, doi:10.1021/acs.accounts.9b00496 (2020). 3 Zhao, C.-X. et al. Semi-Immobilized Molecular Electrocatalysts for High-Performance Lithium–Sulfur Batteries. Journal of the American Chemical Society 143, 19865-19872, doi:10.1021/jacs.1c09107 (2021). 4 Jin, S., Wu, M., Gordon, R. G., Aziz, M. J. & Kwabi, D. G. pH swing cycle for CO2 capture electrochemically driven through proton-coupled electron transfer. Energy & Environmental Science, doi:10.1039/D0EE01834A (2020).
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Papadimitriou, Dimitra N. "Engineering of Optical and Electrical Properties of Electrodeposited Highly Doped Al:ZnO and In:ZnO for Cost-Effective Photovoltaic Device Technology." Micromachines 13, no. 11 (November 13, 2022): 1966. http://dx.doi.org/10.3390/mi13111966.
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Resistivity and transparency of zinc-oxide layers (ZnO) for chalcopyrite photovoltaic technology applications were engineered by activation of the Burstein–Moss (BM) effect at high concentrations of aluminium (Al) and indium (In) dopant. The Al:ZnO and In:ZnO layers were processed by cost-effective, large-area, fast-rate electrochemical deposition techniques from aqueous solution of zinc nitrate (Zn(NO3)2) and dopant trichlorides, at negative electrochemical potential of EC = (−0.8)–(−1.2) V, moderate temperature of 80 °C, and solute dopant concentrations of AlCl3 and InCl3 up to 20 and 15 mM, respectively. Both Al:ZnO and In:ZnO layers were deposited on Mo/glass substrates with ZnO and ZnO/ZnSe buffers (Al:ZnO/ZnO/Mo/glass, In:ZnO/ZnO/ZnSe/Mo/glass), respectively. Based on the band-gap energy broadening of Al:ZnO and In:ZnO originated by the BM effect, maximum carrier concentrations of the order 1020 and 1021 cm−3, respectively, were determined by optical characterization techniques. The (electrical) resistivity values of Al:ZnO calculated from optical measurements were commensurate with the results of electrical measurements (10−4 Ohm·cm). In both cases (Al:ZnO and In:ZnO), calibration of carrier density in dependence of solute dopant concentration (AlCl3 and InCl3) was accomplished. The p–n junctions of Au/In:ZnO/ZnO/ZnSe/CIGS/Mo on glass substrate exhibited current–voltage (I–V) characteristics competing with those of crystalline silicon (c-Si) solar cells.
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Lin, Yuan, Min-Lu Kao, You-Chen Weng, Chang-Fu Dee, Shih-Chen Chen, Hao-Chung Kuo, Chun-Hsiung Lin, and Edward-Yi Chang. "Buffer Traps Effect on GaN-on-Si High-Electron-Mobility Transistor at Different Substrate Voltages." Micromachines 13, no. 12 (December 3, 2022): 2140. http://dx.doi.org/10.3390/mi13122140.
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Substrate voltage (VSUB) effects on GaN-on-Si high electron mobility transistors (HEMTs) power application performance with superlattice transition layer structure was investigated. The 2DEG conductivity and buffer stack charge redistribution can be affected by neutral/ionized donor and acceptor traps. As the donor/acceptor traps are excessively ionized or de-ionized by applying VSUB, the depletion region between the unintentionally doped (UID)/Carbon-doped (C-doped) GaN layer may exhibit a behavior similar to the p–n junction. An applied negative VSUB increases the concentration of both the ionized donor and acceptor traps, which increases the breakdown voltage (BV) by alleviating the non-uniform distribution of the vertical electric field. On the other hand, an applied positive VSUB causes the energy band bending flattener to refill the ionized traps and slightly improves the dynamic Ron degradation. Moreover, the amount of electrons injected into the buffer stack layer from the front side (2DEG channel/Ohmic contact) and the back side (AlN nucleation layer/superlattice transition layer) are asymmetric. Therefore, different VSUB can affect the conductivity of 2DEG through the field effect, buffer trapping effect, and charge redistribution, which can change the electrical performance of the device.
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Wang, Yi, Xinzi Yuan, Xingyu Guan, Kunling Ren, Yan Yang, Jun Luo, and Yantao Zheng. "Mango-Stone-Derived Nitrogen-Doped Porous Carbon for Supercapacitors." Micromachines 13, no. 9 (September 14, 2022): 1518. http://dx.doi.org/10.3390/mi13091518.
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The preparation of N-doped porous carbon (NC-800) is presented via facile mango stone carbonization at 800 °C. The NC-800 material exhibits good cycle stability (the capacity retention is 97.8% after 5000 cycles) and high specific capacitance of 280 F/g at 1 A/g. Furthermore, the assembled symmetric device of NC-800//NCs-800 exhibits about 31.1 Wh/kg of energy density at 800 W/kg in a voltage range of 0–1.6 V. The results of the study suggest that NC-800 may be a promising energy storage material for practical application.
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Ghazanfary, Samereh, Fatemeh Oroojalian, Rezvan Yazdian-Robati, Mehdi Dadmehr, and Amirhossein Sahebkar. "Density Functional Theory Study of Antioxidant Adsorption onto Single- Wall Boron Nitride Nanotubes: Design of New Antioxidant Delivery Systems." Combinatorial Chemistry & High Throughput Screening 22, no. 7 (December 3, 2019): 470–82. http://dx.doi.org/10.2174/1386207322666190930113200.
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Background: Boron Nitride Nanotubes (BNNTs) have recently emerged as an interesting field of study, because they could be used for the realization of developed, integrated and compact nanostructures to be formulated. BNNTs with similar surface morphology, alternating B and N atoms completely substitute for C atoms in a graphitic-like sheet with nearly no alterations in atomic spacing, with uniformity in dispersion in the solution, and readily applicable in biomedical applications with no obvious toxicity. Also demonstrating a good cell interaction and cell targeting. Aim and Objective: With a purpose of increasing the field of BNNT for drug delivery, a theoretical investigation of the interaction of Melatonin, Vitamin C, Glutathione and lipoic acid antioxidants using (9, 0) zigzag BNNTs is shown using density functional theory. Methods: The geometries corresponding to Melatonin, Vitamin C, Glutathione and lipoic acid and BNNT with different lengths were individually optimized with the DMOL3 program at the LDA/ DNP (fine) level of theory. Results: In the presence of external electric field Melatonin, Vitamin C, Glutathione and lipoic acid could be absorbed considerably on BNNT with lengths 22 and 29 Å, as the adsorption energy values in the presence of external electric field are considerably increased. Conclusion: The external electric field is an appropriate technique for adsorbing and storing antioxidants on BNNTs. Moreover, it is believed that applying the external electric field may be a proper method for controlling release rate of drugs.
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Chelfouh, Nora, Gaël Coquil, Steeve Rousselot, Elsa Briqueleur, Gabrielle Foran, and Mickaël Dollé. "Apple Pectin Based Hydrogel Electrolyte for Energy Storage Application." ECS Meeting Abstracts MA2022-01, no. 4 (July 7, 2022): 571. http://dx.doi.org/10.1149/ma2022-014571mtgabs.
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With the increase of portable power sources demand, new technologies, e.g. wearable and flexible electronics, are projected to generate $1.25 billion market by 2022.[1] New storage energy devices are more than ever in demand which requires new specifications in order to be used in those future applications. To achieve this development, we have to minimize the environmental impact in the whole battery life cycle, from conception to degradation of the system, and reduce production costs. Polymer hydrogel electrolyte are one of the promising alternative for processing new flexible batteries.[2] A great hydrogel electrolyte should promise excellent ionic transport pathways and sufficient mechanical strength, not to cause short-circuits. As a matter of fact, hydrogel electrolytes are well-known for their good ionic conductivity. Nevertheless, the original polymers used in these systems don’t take into account the cost of the environmental impact and safety due to the processing or biodegradability of those hydrogels.[3] In this study, we report a new hydrogel-based electrolyte material made by apple pectin. This presentation will mainly focus on the interactions between pectin functional groups, water and ions using solid NMR spectroscopy. Thermal properties will be discussed based on differential scanning calorimetry analysis. Electrical and electrochemical characterisctics obtained by electrochemical impedance spectroscopy, galvanostatic cycling and cyclic voltametry will demonstrate the applicability of such hydrogel electrolyte. This study could promote a great innovation in the energy storage field, by recycling one of apple peel’s component (which is the main waste in preserves manufacturing[4]) into a hydrogel electrolyte. References [1] N. R. C. Canada in Environmentally friendly printed batteries, Vol. Boucherville, Quebec, 2021. [2] C. Y. Chan, Z. Wang, H. Jia, P. F. Ng, L. Chow and B. Fei, Journal of Materials Chemistry A 2021, 9, 2043-2069. [3] Y. Huang, M. Zhong, F. Shi, X. Liu, Z. Tang, Y. Wang, Y. Huang, H. Hou, X. Xie and C. Zhi, Angewandte Chemie International Edition 2017, 56, 9141-9145. [4] B. S. Virk and D. S. Sogi, International Journal of Food Properties 2004, 7, 693-703.
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Almadani, Ibrahim Khalil, Ibrahim Sufian Osman, and Nasir Ghazi Hariri. "In-Depth Assessment and Optimized Actuation Method of a Novel Solar-Driven Thermomechanical Actuator via Shape Memory Alloy." Energies 15, no. 10 (May 22, 2022): 3807. http://dx.doi.org/10.3390/en15103807.
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Currently, energy demand is more significant than ever due to population growth and advances in recent technologies. In order to supply more energy while maintaining a healthy environment, renewable energy resources are employed. This paper proposes a novel solar-driven shape memory alloy thermomechanical actuator as an eco-friendly solution for solar thermal applications. The proposed actuator was assessed numerically and experimentally. The numerical tests showed that the designed actuation mechanism’s inner temperature has a minimum variation per day of about 14 °C and a temperature variation of 19 °C for most days of the year, which allows for proper activation and deactivation of the actuator. As for the experimental tests, the presented actuation mechanism achieved a bi-directional force of over 150 N, where the inner temperatures of the actuator were recorded at about 70.5 °C while pushing forces and 28.9 °C while pulling forces. Additionally, a displacement of about 127 mm was achieved as the internal temperature of the actuator reached 70.4 °C. The work presented adds to the body of knowledge of a novel solar-based self-driven actuation mechanism that facilitates various applications for solar thermal systems.
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Fu, Yu, Sichen Wei, Yingjie Chen, Huamin Li, Yuguang Chris Li, and Fei Yao. "Novel Hollow Spherical Carbon Nitride Synthesis and Its Application in Zinc-Air Batteries." ECS Meeting Abstracts MA2022-02, no. 8 (October 9, 2022): 654. http://dx.doi.org/10.1149/ma2022-028654mtgabs.
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The pressing need for carbon emission reduction calls for a rapid move toward electrified mobility and expanded deployment of solar and wind on the electric grid. As a result, high-performance electrical energy storage systems are highly demanded. Rechargeable lithium-ion batteries (LIBs) are the most widely used battery system in portable electronics and electric vehicles nowadays because of their high energy per unit mass, power-to-weight ratio, and high-temperature performance. However, concerns about their high cost (250 US$ kW h−1), inherent safety hazards, and limited cathode capacity have motivated the investigation beyond Li-ion technology. In particular, Zn-air batteries (ZABs) have emerged as a much more sustainable option than LIBs with high energy densities of 1218 Wh kg-1 (gravimetric) and 6136 Wh L-1 (volumetric) benefiting from the earth-abundant, low-cost, and environmentally friendly nature of Zn metal and the ample oxygen supply in ambient air. One of the major challenges in ZABs research is the inefficient oxygen reaction kinetics at the air cathode. Among various proposed bifunctional oxygen catalysts, metal-free carbon-based catalysts have drawn tremendous attention due to their potential in reducing the costs and environmental impacts of noble and transition metal-based catalysts. In particular, nitrogen-doped carbonaceous materials have been recognized as one of the most promising catalysts because of their increased electrical conductivity via stimulating the delocalization of electrons and induced electron depletion on carbon atoms which optimize valence orbital energy for active sites. Nevertheless, conventional post-synthesis doping methods not only involve complicated experimental setups but also offer limited nitrogen doping (1 - 20%) levels along with poor control over C-N configurations. Accordingly, a facile synthesis method enabling high nitrogen doping content with the C-N configuration controllability is highly demanded for high-performance ZABs. In this report, we successfully synthesized high nitrogen-content hollow carbon spheres (H-CxNy) via a novel metal-assisted denitrification (MAD) process. Specifically, we employed Zn metal and low-cost graphitic carbon nitride (g-C3N4) as catalyst and precursor, respectively, to construct the H-CxNy microstructures. During the annealing process, the Zn metal reacts with nitrogen during pyrolysis of the g-C3N4 and converts it into heat-stable Zn3N2 intermediates, which not only avoids the direct volatilization of nitrogen content but also displaces carbon atoms and subsequently rearranges carbon and nitrogen atoms into H-CxNy spherical structures. The content and the configuration of the nitrogen species on the hollow spherical skeleton were successfully modulated by controlling the synthesis conditions. To investigate the structure-property-activity relationship, scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy, Raman spectroscopy, and various electrochemical characterizations were conducted. The optimized H-CxNy sample demonstrated excellent bifunctional catalysis performance with a stable cyclic performance when employed as an air electrode in ZABs.
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Hoffmann, Viola, Dennis Jung, Muhammad Jamal Alhnidi, Lukas Mackle, and Andrea Kruse. "Bio-Based Carbon Materials from Potato Waste as Electrode Materials in Supercapacitors." Energies 13, no. 9 (May 11, 2020): 2406. http://dx.doi.org/10.3390/en13092406.
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This study investigates the production of biobased carbon materials from potato waste and its application in energy storage systems such as supercapacitors. Three different categories of carbons were produced: hydrochar (HC) from hydrothermal carbonization (HTC) at three different temperatures (200 °C, 220 °C, 240 °C) and two different duration times (two hours and five hours), pyrolyzed hydrochar (PHC) obtained via pyrolysis of the HTC chars at 600 °C and 900 °C for two hours and pyrochar from the pyrolysis of biomass at 600 °C and 900 °C for two hours. The carbon samples were analysed regarding their physico-chemical properties such as elemental composition, specific surface area, bulk density and surface functionalities as well as their electrochemical characteristics such as electric conductivity and specific capacity via cyclic voltammetry. N- and O-enriched carbon materials with promising specific surface areas of up to 330 m2 g−1 containing high shares of microporosity were produced. Electric conductivities of up to 203 S m−1 and specific capacities of up to 134 F g−1 were obtained. The presence of high contents of oxygen (4.9–13.5 wt.%) and nitrogen (3.4–4.0 wt.%) of PHCs is assumed to lead to considerable pseudocapacitive effects and favor the high specific capacities measured. These results lead to the conclusion that the potential of agricultural biomass can be exploited by using hydrothermal and thermochemical conversion technologies to create N- and O-rich carbon materials with tailored properties for the application in supercapacitors.
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Tang, Hua, Hang Xu, Lin Chen, Hao Zhu, and Qingqing Sun. "Anomalous PBTI Effects in N-Type Super Junction under High Gate Voltage Stress." Electronics 11, no. 9 (April 25, 2022): 1362. http://dx.doi.org/10.3390/electronics11091362.
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In this work, an anomalous thick oxide-degradation phenomenon in n-type 650-V class super-junction VDMOS transistors is investigated. An unexpected threshold voltage (Vt) decrease was observed with high positive bias temperature instability stress, and the saturation current (IDsat) increases with the stress time. Repeatable and reproducible behaviors have been achieved from multiple devices under test. Based on simulation and experimental results, it is found that the high-energy electrons (caused by high positive gate voltage) in the n-type region at the bottom of the gate oxide layer (top of the N-pillar) are injected into the gate oxide. The high-energy electrons generate electron-hole pairs during the transport to the anode, leaving holes in the gate oxide layer, and thus decreased Vt and increased IDsat. Finally, C-V measurement is also carried out which further confirms the above analysis.
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Tang, Hua, Hang Xu, Lin Chen, Hao Zhu, and Qingqing Sun. "Anomalous PBTI Effects in N-Type Super Junction under High Gate Voltage Stress." Electronics 11, no. 9 (April 25, 2022): 1362. http://dx.doi.org/10.3390/electronics11091362.
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In this work, an anomalous thick oxide-degradation phenomenon in n-type 650-V class super-junction VDMOS transistors is investigated. An unexpected threshold voltage (Vt) decrease was observed with high positive bias temperature instability stress, and the saturation current (IDsat) increases with the stress time. Repeatable and reproducible behaviors have been achieved from multiple devices under test. Based on simulation and experimental results, it is found that the high-energy electrons (caused by high positive gate voltage) in the n-type region at the bottom of the gate oxide layer (top of the N-pillar) are injected into the gate oxide. The high-energy electrons generate electron-hole pairs during the transport to the anode, leaving holes in the gate oxide layer, and thus decreased Vt and increased IDsat. Finally, C-V measurement is also carried out which further confirms the above analysis.
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Danilov, Pavel, Evgeny Kuzmin, Elena Rimskaya, Jiajun Chen, Roman Khmelnitskii, Alexey Kirichenko, Nikolay Rodionov, and Sergey Kudryashov. "Up/Down-Scaling Photoluminescent Micromarks Written in Diamond by Ultrashort Laser Pulses: Optical Photoluminescent and Structural Raman Imaging." Micromachines 13, no. 11 (November 1, 2022): 1883. http://dx.doi.org/10.3390/mi13111883.
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Elongated photoluminescent micromarks were inscribed inside a IaAB-type natural diamond in laser filamentation regime by multiple 515 nm, 0.3 ps laser pulses tightly focused by a 0.25 NA micro-objective. The micromark length, diameter and photoluminescence contrast scaled as a function of laser pulse energy and exposure, coming to a saturation. Our Raman/photoluminescence confocal microscopy studies indicate no structural diamond damage in the micromarks, shown as the absent Raman intensity variation versus laser energy and exposition along the distance from the surface to the deep mark edge. In contrast, sTable 3NV (N3)-centers demonstrate the pronounced increase (up to 40%) in their 415 nm zero-phonon line photoluminescence yield within the micromarks, and an even higher—ten-fold—increase in NV0-center photoluminescence yield. Photogeneration of carbon Frenkel “interstitial–vacancy” (I–V) pairs and partial photolytic dissociation of the predominating 2N (A)-centers were suggested to explain the enhanced appearance of 3NV- and NV-centers, apparently via vacancy aggregation with the resulting N (C)-centers or, consequently, with 2N- and N-centers.
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Mustapić, Nenad, Vladislav Brkić, Željko Duić, and Toni Kralj. "Thermodynamic Optimization of Advanced Organic Rankine Cycle Configurations for Geothermal Energy Applications." Energies 15, no. 19 (September 23, 2022): 6990. http://dx.doi.org/10.3390/en15196990.
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The Organic Rankine Cycle (ORC) is commonly accepted as a viable technology to convert from low to medium temperature geothermal energy into electrical energy. In practice, the reference technology for converting geothermal energy to electricity is the subcritical simple ORC system. Over time, geothermal ORC plants with more complex configurations (architectures) have been developed. In the open literature, a large number of advanced architectures or configurations have been introduced. An analysis of the scientific literature indicates that there is some confusion regarding the terminology of certain advanced ORC system architectures. A new categorization of advanced configurations has been proposed, with a special emphasis on the application of geothermal energy. The basic division of advanced plant configurations is into dual-pressure and dual-stage ORC systems. In this study, the real potential of advanced ORC architectures or configurations to improve performance as compared with the simple ORC configuration was explored. The research was conducted for a wide range of geothermal heat source temperatures (from 120 °C to 180 °C) and working fluids. Net power output improvements as compared with the basic subcritical simple ORC (SORC) configuration were examined. The ability to produce net power with different ORC configurations depends on the magnitude of the geothermal fluid temperature and the type of working fluid. At a lower value of geothermal fluid temperature (120 °C), the most net power of 18.71 (kW/(kg/s)) was realized by the dual-pressure ORC (DP ORC configuration) with working fluid R1234yf, while the double stage serial-parallel ORC configuration with a low-temperature preheater in a high-temperature stage ORC (DS parHTS LTPH ORC) generated 18.51 (kW/(kg/s)) with the working fluid combination R1234yf/R1234yf. At 140 °C, three ORC configurations achieved similar net power values, namely the simple ORC configuration (SORC), the DP ORC configuration, and the DS parHTS LTPH ORC configuration, which generated 31.03 (kW/(kg/s)) with R1234yf, 31.07 (kW/(kg/s)) with R1234ze(E), and 30.96 (kW/(kg/s)) with R1234ze(E)/R1234yf, respectively. At higher values of geothermal fluid temperatures (160 °C and 180 °C) both the SORC and DP ORC configurations produced the highest net power values, namely 48.58 (kW/(kg/s)) with R1234ze(E), 67.23 (kW/(kg/s)) with isobutene for the SORC configuration, and 50.0 (kW/(kg/s)) with isobutane and 69.67 (kW/(kg/s)) with n-butane for the the DP ORC configuration.
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Park, Sangwoo, and Sangjin Byun. "A 0.026 mm2 Time Domain CMOS Temperature Sensor with Simple Current Source." Micromachines 11, no. 10 (September 28, 2020): 899. http://dx.doi.org/10.3390/mi11100899.
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This paper presents a time domain CMOS temperature sensor with a simple current source. This sensor chip only occupies a small active die area of 0.026 mm2 because it adopts a simple current source consisting of an n-type poly resistor and a PMOS transistor and a simple current controlled oscillator consisting of three current starved inverter delay cells. Although this current source is based on a simple architecture, it has better temperature linearity than the conventional approach that generates a temperature-dependent current through a poly resistor using a feedback loop. This temperature sensor is designed in a 0.18 μm 1P6M CMOS process. In the post-layout simulations, the temperature error was measured within a range from −1.0 to +0.7 °C over the temperature range of 0 to 100 °C after two point calibration was carried out at 20 and 80 °C, respectively. The temperature resolution was set as 0.32 °C and the temperature to digital conversion rate was 50 kHz. The energy efficiency is 1.4 nJ/sample and the supply voltage sensitivity is 0.077 °C/mV at 27 °C while the supply voltage varies from 1.65 to 1.95 V.
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Zuo, Xi, Li Chen, Wenjun Pan, Xingchen Ma, Tongqing Yang, and Xiaoqing Zhang. "Fluorinated Polyethylene Propylene Ferroelectrets with an Air-Filled Concentric Tunnel Structure: Preparation, Characterization, and Application in Energy Harvesting." Micromachines 11, no. 12 (December 1, 2020): 1072. http://dx.doi.org/10.3390/mi11121072.
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Fluorinated polyethylene propylene (FEP) bipolar ferroelectret films with a specifically designed concentric tunnel structure were prepared by means of rigid-template based thermoplastic molding and contact polarization. The properties of the fabricated films, including the piezoelectric response, mechanical property, and thermal stability, were characterized, and two kinds of energy harvesters based on such ferroelectret films, working in 33- and 31-modes respectively, were investigated. The results show that the FEP films exhibit significant longitudinal and radial piezoelectric activities, as well as superior thermal stability. A quasi-static piezoelectric d33 coefficient of up to 5300 pC/N was achieved for the FEP films, and a radial piezoelectric sensitivity of 40,000 pC/N was obtained in a circular film sample with a diameter of 30 mm. Such films were thermally stable at 120 °C after a reduction of 35%. Two types of vibrational energy harvesters working in 33-mode and 31-mode were subsequently designed. The results show that a power output of up to 1 mW was achieved in an energy harvester working in 33-mode at a resonance frequency of 210 Hz, referring to a seismic mass of 33.4 g and an acceleration of 1 g (g is the gravity of the earth). For a device working in 31-mode, a power output of 15 μW was obtained at a relatively low resonance frequency of 26 Hz and a light seismic mass of 1.9 g. Therefore, such concentric tunnel FEP ferroelectric films provide flexible options for designing vibrational energy harvesters working either in 33-mode or 31-mode to adapt to application environments.
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Faiz, Faizan Ul Hassan, Rabia Shakoor, Abdur Raheem, Farhana Umer, Nadia Rasheed, and Muhammad Farhan. "Modeling and Analysis of 3 MW Solar Photovoltaic Plant Using PVSyst at Islamia University of Bahawalpur, Pakistan." International Journal of Photoenergy 2021 (May 29, 2021): 1–14. http://dx.doi.org/10.1155/2021/6673448.
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Conventional means of electrical energy generation are costly, create environmental pollution, and demand a high level of maintenance and also going to end one day. This has made it crucial to exploit the untapped prospective of the environmentally friendly renewable energy resources. To address this problem, present research proposed an efficient, everlasting, and environment-friendly grid-connected PV system at The Islamia University of Bahawalpur, Pakistan (latitude: 29° 22 ′ 34 ″ N, longitude: 71° 44 ′ 57 E). Bahawalpur is one of those sites where the potential of solar energy is immense. The global daily horizontal solar irradiance at the site is 1745.85 kWh/m2, having average solar irradiation of 5.9 kWh/m2 per day, and the ambient average temperature is about 25.7°C. In this research, the performance ratio and different power losses just like soiling, PV module losses, inverter, and losses due to temperature are taken into account and calculated by using PVSyst. The coal saving per day is 15369.3 kg which is equal to planting 147600 teak trees over a lifetime. The cost of the energy produced is 0.11 US $/kWh whereas in Pakistan the conventional energy tariff is 0.18 $/kWh. From the simulation results, the value of PR comes out 83.8%, and the CUF value is 16% with a total energy generation of 4908 MWh/year. The performance analysis of this grid-connected system would help in the designing, analysis, operation, and maintenance of the new grid-connected systems for different locations.
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Pei, Younan, Xueshan Han, Pingfeng Ye, Yumin Zhang, Mingbing Li, and Huizong Mao. "Distributionally Robust Unit Commitment with N-k Security Criterion and Operational Flexibility of CSP." Energies 15, no. 23 (December 5, 2022): 9202. http://dx.doi.org/10.3390/en15239202.
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In order to reduce the conservatism of the robust optimization method and the complexity of the stochastic optimization method and to enhance the ability of power systems to deal with occasional line fault disturbance, this paper proposes a distributionally robust unit commitment (DRUC) model with concentrating solar power (CSP) operational flexibility and N-k safety criterion under distributed uncertainty. According to the limited historical sample data, under the condition of satisfying a certain confidence level, based on the imprecise Dirichlet model (IDM), an ambiguity set is constructed to describe the uncertainty of transmission line fault probability. Through the identification of the worst probability distribution in the ambiguity set, the adaptive robust optimal scheduling problem is transformed into a two-stage robust optimization decision model under the condition of deterministic probability distribution. The CSP flexibility column and constraint generation (C&CG) algorithm is used to process the model and the main problem and subproblem are solved by using the Big-M method, linearization technique, and duality principle. Then, a mixed integer linear programming problem (MILP) model is obtained, which effectively reduces the difficulty of solving the model. Finally, case studies on the IEEE 14 bus system and the IEEE 118 bus system demonstrate the efficiency of the proposed method, such as enhancing the ability of power systems to cope with occasional line fault disturbances and reducing the conservatism of the robust optimization method.
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Song, Wenming, Changmeng Xu, Mai Li, Zhi Cheng, Yunjie Liu, Peng Wang, and Zhiming Liu. "Cobalt Nanocluster-Doped Carbon Micro-Spheres with Multilevel Porous Structure for High-Performance Lithium-Sulfur Batteries." Energies 16, no. 1 (December 26, 2022): 247. http://dx.doi.org/10.3390/en16010247.
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Lithium-Sulfur batteries (Li-S batteries) have gained great interest in next-generation energy storage systems due to their high energy density and low-cost sulfur cathodes. There is, however, a serious obstacle in the commercial application of Li-S batteries due to the poor kinetics of the redox process at the sulfur cathode and the “shuttle effect” caused by lithium polysulfide (LiPSs). Herein, we report the synthesis of a sulfur cathode host material that can drastically inhibit the “shuttle effect” and catalyze the conversion of LiPSs by a simple electrostatic spray technique, namely, cobalt (Co) nanoclusters doped with N-containing porous carbon spheres (Co/N-PCSs). The results show that Co/N-PCSs has catalytic activity for the transformation of liquid LiPSs to solid Li2S and alleviates the notorious “shuttle effect.” This new sulfur cathode exhibits stable running for 300 cycles accompanied by a capacity of 650 mAh g−1 at a current density of 1 C, a capacity fading rate of 0.051% per cycle, and a Coulombic efficiency maintained at close to 100%. The results demonstrate that Co/N-PCSs offers the possibility of practical applications for high-performance Li-S batteries.
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Meng, Qingzhi, Qijing Lin, Weixuan Jing, Na Zhao, Ping Yang, and Dejiang Lu. "Investigation on the Effect of Annealing Temperature on the Side Ohmic Contact Characteristics for Double Channel GaN/AlGaN Epitaxial Layer." Micromachines 13, no. 5 (May 19, 2022): 791. http://dx.doi.org/10.3390/mi13050791.
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A side ohmic contact mode for the double channel GaN/AlGaN epitaxial layer is proposed in this paper. Rectangle transmission line model (TLM) electrodes are prepared, and the specific contact resistance is tested at the annealing temperatures from 700 °C to 850 °C. The results show that the minimum specific contact resistance is 2.58 × 10−7 Ω·cm2 at the annealing temperature of 750 °C, which is three to four times lower than the surface contact mode. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS), and atomic force microscope (AFM) were carried out for the analysis of the morphology, element composition, and the height fluctuation at the contact edge. With the increase in the annealing temperature, the specific contact resistance decreases due to the alloying of electrodes and the raised number of N vacancies. However, when the annealing temperature exceeds 800 °C, the state of the stress in the electrode films transforms from compressive stress to tensile stress. Besides, the volume expansion of metal electrode film and the increase in the roughness at the contact edge leads to the degradation of the side ohmic contact characteristics.
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Butt, Iftikhar Bashir, Jinwang Tan, Adeel Waqas, Majid Ali, Adeel Javed, and Asfand Yar Ali. "Effect of Modified Flow Schemes of Heat Transfer Fluid on the Performance of a Solar Absorption–Cooling System for an Educational Building in Pakistan." Applied Sciences 10, no. 9 (May 11, 2020): 3327. http://dx.doi.org/10.3390/app10093327.
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Performance of solar absorption cooling systems (SACS) is the focus of contemporary studies for decreasing the electrical energy consumption of buildings as the conventional cooling system of buildings is the main consumer of electrical energy during the summer season in hot–humid climates. In this study, the performance analysis of SACS by manipulating different flow schemes to the heat transfer fluid between different components of the system was performed. TRNSYS model of SACS in an education building located at the city of Peshawar (34.00 N, 71.54 E), Pakistan to encounter the peak cooling load of 108 kW (during operating hours of the building i.e., 09 a.m. to 05 p.m.) is developed and all possible flow schemes of heat transfer fluid between the system’s components were compared. In Scheme-1 (S-1), a conventional flow pattern is used in which the hot water exiting from the chiller unit flows directly toward the stratified thermal storage unit. In Scheme-2 (S-2), the modified flow pattern of hot water exiting from the chiller unit will divert towards the auxiliary unit, if its temperature exceeds the temperature at the hot side outlet of the tank. Another modified flow pattern is Scheme-3 (S-3) in which the hot water leaving the chiller to keep diverting towards the auxiliary unit unless the outlet temperature from the hotter side of the tank would reach the minimum driving temperature (109 °C) of the chiller’s operation. Simulations in TRNSYS evaluates the SACS’s performance of all the schemes (conventional and modified) for the whole summer season and for each month. In general, S-3 with evacuated tube solar collector results in better primary energy saving with the smallest collector area per kilowatt for achieving 50% primary energy saving for the whole summer season.
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Zhang, Ji-Guang, Xia Cao, Phung M.-L. LE, Yan Jin, Ju-Myung Kim, and Wu Xu. "Development of Anode-Free Metal Batteries." ECS Meeting Abstracts MA2022-01, no. 1 (July 7, 2022): 36. http://dx.doi.org/10.1149/ma2022-01136mtgabs.
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Ever increasing need for electrical vehicles (EVs) continually pushes the boundary of high-density energy storage systems. To date, the state of the art of lithium (Li) ion batteries (LIBs) consisting of graphite anode and high voltage Li intercalation cathodes cannot satisfy the energy demand from these applications. By replacing graphite anode with Li metal anode (LMA), specific energy density of Li metal batteries (LMBs) can increase by more than 50% because LMA has a much higher specific capacity (3820 mAh g-1) than that of graphite (372 mAh g-1). To further increase the energy density of Li batteries, the concept of “anode-free” Li batteries (AFLBs) has been explored. Similar approach can also be used in “anode-free” sodium (Na) batteries (AFSBs) to further improve their energy densities. In this work, we will report our recent work on the development of AFLBs and AFSBs. The common challenges in these batteries will be analyzed and compared first. Several approaches, including development of novel electrolytes, substrate treatment, optimization of testing protocol and environment conditions, have been adopted to increase the cycle life of these batteries. At last, future perspective and application of anode-fee metal batteries will be discussed. References Niu, C.; Liu, D.; Lochala, J. A.; Anderson, C. S.; Cao, X.; Gross, M. E.; Xu, W.; Zhang, J.-G.; Whittingham, M. S.; Xiao, J.; Liu, J., Balancing interfacial reactions to achieve long cycle life in high-energy lithium metal batteries. Nature Energy 2021. Zhang, J.-G., Anode-less. Nature Energy 2019, 4 (8), 637-638. Pereira, N.; Amatucci, G. G.; Whittingham, M. S.; Hamlen, R., Lithium–titanium disulfide rechargeable cell performance after 35 years of storage. Journal of Power Sources 2015, 280, 18-22. Boyle, D. T.; Huang, W.; Wang, H.; Li, Y.; Chen, H.; Yu, Z.; Zhang, W.; Bao, Z.; Cui, Y., Corrosion of lithium metal anodes during calendar ageing and its microscopic origins. Nature Energy 2021.
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Bellas Chatzigeorgis, Georgios, Justin B. Haskins, and James B. Scoggins. "Transport properties for neutral C, H, N, O, and Si-containing species and mixtures from the Gordon and McBride thermodynamic database." Physics of Fluids 34, no. 8 (August 2022): 087106. http://dx.doi.org/10.1063/5.0098060.
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Accurate transport properties of non-ionized gas mixtures of C, H, O, N, and Si-containing species at temperatures up to 4000 K are essential in many scientific fields. Mixture transport properties are computed through the solution of linear transport systems, requiring collision integrals as functions of temperature for each binary collision pair in the mixture. Due to the dimensionality of the problem, no such database exists for all the 180 hydrocarbons and silicon species detailed in the nine-coefficient polynomial thermodynamic database of Gordon and McBride, widely used in many applications. This constraint was overcome by using a phenomenological inter-molecular potential energy surface suitable for transport properties, which describes the pair interaction approximated with two fundamental species physical properties, namely the dipole electric polarizability and the number of effective electrons participating in the interaction. These two parameters were calculated with ab initio quantum chemistry calculations, since they were not always available in literature. The studied methodology was verified and validated against other approaches at a species and collision integral level. Transport properties for a variety of equilibrium mixtures, including planetary atmospheres and chemical compositions of thermal protection materials relevant to aerospace applications, were calculated, assessing the predictive capabilities of this new database.
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Wisinska, Natalia H., Magdalena Skunik-Nuckowska, Sławomir Dyjak, Wladyslaw Wieczorek, and Pawel J. Kulesza. "Poly(norepinephrine) As a Functional Additive for Hybrid Cellulose/Agarose-Based Hydrogel Membranes: Application to Supercapacitors." ECS Meeting Abstracts MA2022-02, no. 54 (October 9, 2022): 2051. http://dx.doi.org/10.1149/ma2022-02542051mtgabs.
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A rapidly growing interest in renewable energy sources requires not only developing efficient energy storage systems but also incorporating a greater number of eco-friendly components. Electrochemical double-layer capacitors (EDLCs) are a class of energy storage devices capable to store the electrical charge due to the separation of oppositely charged ions in the electrical field which results in the formation of an electrical double layer (EDL) at the electrode/electrolyte interface. EDLCs consist in general of two porous carbon-based electrodes pre-soaked with electrolyte and separated with a membrane (separator). The simple electrostatic mechanism of energy storage, coupled with a lack of chemical changes and faradaic transitions during operation, results in high electrical capacitance compared to classical capacitors, significantly higher power density in contrast to batteries, and practically unlimited life span. Currently, commercial EDLCs typically rely on organic solvents, such as acetonitrile or propylene carbonate, with the addition of ionically-conductive salts. However, there are several drawbacks when it comes to practical applications involving particular low conductivity, toxicity, flammability and high cost. This resulted in an increased interest in aqueous electrolytes such as KOH, H2SO4 or simple inorganic salts, which although they have a limited potential window, exhibit many positive features including higher ionic conductivity, lower viscosity, increased safety, lower cost and ease of assembly under ambient atmosphere. Modern and technologically advanced charge storage devices often require high safety flexible and deformable devices for specific applications. However, at the current state-of-the-art, the EDLCs suffer from two prominent limitations (i) the possibility of electrolyte leakage and (ii) high standards of technology to safely encapsulate electrolytes in the device. Therefore, a lot of research is held to develop alternatives for currently used liquid (aqueous and organic) electrolytes. One of the solutions to overcome these limitations are solid-state EDLCs. Those systems use an ionically-conductive polymer or hydrogel membrane, which serves as both the separator and the electrolyte. Cellulose, built of β-(1→4)-linked D-glucose units, is one of the most prevalent and easily degradable biopolymers. Albeit, its wide availability, biodegradability and low cost, the usage of cellulose is limited due to insolubility in most common solvents. The recent alternative, to toxic and flammable organic compounds, such as N, N- dimethylformamide/N2O4, N-methylmorpholine oxide (NMMO), are ionic liquids (ILs), that have been gaining lately a lot of attention in energy storage systems. Various ILs based on imidazolium, pyridinium and ammonium cation paired with strongly basic anion (e.g., OAc-, HCOO-) were also recently used to dissolve cellulose. However, the requirements of high-purity syntheses and the cost of some of the cations/anions may affect a large scale application. Therefore, our research refers to an alternative route of chemical regeneration of microcrystalline cellulose, i.e. its dissolution using an aqueous mixture of NaOH/urea, and further processing into a hydrogel membrane in the presence of cross-linking agent epichlorohydrin. To improve the mechanical strength and electrolyte uptake, in-situ polymerized norepinephrine and agarose were subsequently incorporated obtaining an interpenetrating polymer network (IPN). The structure and morphology of the membranes were characterized with SEM/EDX, CP/MAS 13C-NMR, AT-FTIR, TGA, contact angle, and elementary analysis. The ionic conductivity was determined using impedance spectroscopy over a wide range of temperatures (5-60°C). The relation between stress and strain in the materials was also determined to diagnose the mechanical properties. The cellulose-based hydrogel membranes were further used as a support for various aqueous electrolytes, including H2SO4, Na2SO4, i.e. most commonly used for aqueous EDLCs. Also, the alternative electrolyte was used, i.e. silicotungstic acid, H4SiW12O40 which according to our recent results seems to be a promising candidate to replace conventional acidic electrolytes [1]. The designed systems were compared, in terms of energy, power and cycleability, with their analogues using conventional polypropylene separators and a liquid electrolyte. [1] N.H. Wisinska, M. Skunik-Nuckowska, S. Dyjak, P.J. Kulesza, Factors affecting the performance of electrochemical capacitors operating in Keggin-type silicotungstic acid electrolyte, Appl. Surf. Sci. 530 (2020) 147273, https://doi.org/10.1016/j.apsusc.2020.147273 Acknowledgement Financial support was provided by the National Science Center under Preludium 19 grant no. 2020/37//N/ST4/01679. This work was implemented as a part of Operational Project Knowledge Education Development 2014–2020 co-financed by the European Social Fund, Project No POWR.03.02.00-00-I007/16-00 (POWER 2014-2020)
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Giron Rodriguez, Carlos Andres, Asger Barkholt Moss, Sahil Garg, Ib Chorkendorff, and Brian Seger. "Understanding the Temperature Effects on CO2 Electrolysis Performance at High Current Densities." ECS Meeting Abstracts MA2022-01, no. 39 (July 7, 2022): 1783. http://dx.doi.org/10.1149/ma2022-01391783mtgabs.
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The CO2 electrolysis driven with renewable sources is a promising alternative to mitigate greenhouse gas emissions by converting CO2 into valuable feedstocks and storing renewable electrical energy 1. Membrane electrode assemblies (MEAs) equipped with gas diffusion electrodes (GDEs) have shown great potential to overcome the current limitation of aqueous-fed systems while bringing this technology to economically-competing levels 2. In the last decade, many studies have been devoted to developing efficient catalyst materials and reactor designs; however, the effect of operating conditions such as temperature has not been thoroughly studied3. Given that the temperature affects CO2 electrolysis in a complex way (simultaneous effects on the CO2 diffusivity, solubility, the ionic conductivity of the membrane, and surface wettability of the GDE4), a systematic investigation is necessary to determine temperature influence on the product distribution In this study, we investigate the temperature effects on CO2 electrolysis of Cu-based GDEs in an MEA-based approach in a temperature range between 25 and 80˚C, to enhance the selectivity of C2+ products and the energy efficiency while suppressing the hydrogen evolution (HER) and the degradation of the GDE and the membrane. For this investigation, a robust system for controlling and measuring the temperature of all the system components was developed, and we simultaneously set up proper guidelines to perform these electrocatalytic temperature measurements in a consistent and reproducible way. For evaluating the temperature influence on electrocatalytic performance, a series of electrochemical measurements such as linear sweep voltammetry (LSV), double-layer capacitance measurements (DLC), potentiostatic and galvanostatic experiments were performed. The obtained results provide insights into how CO2 diffusion, reaction kinetics, and CO2 mass transport vary with temperature and affect the overall performance. We observed improvement in reaction rates and a drop in cell voltages at higher temperatures due to the enhancement of membranes' ionic conductivity and water management. The experiments focused on selectivity and product crossover revealed a specific trend at temperatures above 60˚C for gas and liquid products, setting up the optimal conditions for a stable operation with higher faradaic efficiencies of carbon-based compounds. 1 A. Vasileff, Y. Zheng and S. Z. Qiao, Adv. Energy Mater., 2017, 7, 1–21. 2 T. Burdyny and W. A. Smith, Energy Environ. Sci., 2019, 12, 1442–1453. 3 B. Endrődi, G. Bencsik, F. Darvas, R. Jones, K. Rajeshwar and C. Janáky, Prog. Energy Combust. Sci., 2017, 62, 133–154. 4 A. Löwe, C. Rieg, T. Hierlemann, N. Salas, D. Kopljar, N. Wagner and E. Klemm, ChemElectroChem, 2019, 6, 4497–4506.
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Boualam, Soukayna Riffi, Mariya Ouaissa, Mariyam Ouaissa, and Abdellatif Ezzouhairi. "Secure and efficient routing protocol for low-power and lossy networks for IoT networks." Indonesian Journal of Electrical Engineering and Computer Science 27, no. 1 (July 1, 2022): 478. http://dx.doi.org/10.11591/ijeecs.v27.i1.pp478-487.
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R outing p rotocol for l ow p ower and l ossy (RPL) is destined to support the specific requirements of l ow p ower and l ossy n etworks (LLN). This type of network suffers from the problem of determining and securing a routing protocol to best suit an environment. This article aims to present a new version of the efficient and secure RPL protocol. The proposed scheme consists of two parts : i) Proposing a new o bjective f unction (OF) based RPL which combines three nodes and links metrics are: e xpected r etransmission n umber (ETX), h ope c ount (HC), and the residual energy in order to have a precise decision to c hoose the optimal way to the des tination. ii) To securing the new efficient RPL protocol by combining an improved Diffie - Hellman (DH) algorithm for a robust key exchange model with k eyed - h ash m essage a uthentication c ode (HMAC) to ensure the authentication and integrity of RPL data exchan ged. To verify the level of security, we apply a formal verification using AVISPA tool which indicate that the s ecure and e fficient RPL (SE-RPL) achieve all security requirements. Simulation results on the Contiki platform illustrate that our proposed is m ore efficient in terms of p acket d elivery r atio (PDR) and energy compared to others standard OF.
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Zhang, Hongguang, Tanghan Wu, Lei Tang, Ziye Ling, Zhengguo Zhang, and Xiaoming Fang. "Preparation and Thermal Model of Tetradecane/Expanded Graphite and A Spiral Wavy Plate Cold Storage Tank." Energies 15, no. 24 (December 13, 2022): 9435. http://dx.doi.org/10.3390/en15249435.
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A cold storage unit can store the cold energy off-peak and release it for building cooling on-peak, which can reduce the electricity load of air conditioning systems. N-tetradecane is a suitable cold storage material for air conditioning, with a phase change temperature of is 4–8 °C and a phase change enthalpy of 200 kJ/kg. However, its low thermal conductivity limits the application of n-Tetradecane for high-power cold storage/release. This paper prepares a tetradecane/expanded graphite (EG) composite phase change material (CPCM), whose thermal conductivity can be increased up to 21.0 W/m·K, nearly 100 times over the raw n-tetradecane. A novel model to predict the maximum loading fraction of paraffin in the EG matrix is presented, with an error within 1.7%. We also develop a thermal conductivity model to predict the thermal conductivity of the CPCM precisely, with an error of less than 10%. In addition, an innovative spiral wave plate cold storage tank has been designed for the tetradecane/EG composite. The power and energy density of the cold storage tank are significantly improved compared to that of raw tetradecane. The energy density reaches 40 kWh/m3, which is high among the organic PCM thermal storage tank. This paper shows the significance of thermal conductivity enhancement in designing a cold storage tank.
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Wang, Cheng, Yibo Wang, Zhaoping Shi, Wenhua Luo, Junjie Ge, Wei Xing, Ge Sang, and Changpeng Liu. "RuCo Alloy Nanoparticles Embedded into N-Doped Carbon for High Efficiency Hydrogen Evolution Electrocatalyst." Energies 15, no. 8 (April 15, 2022): 2908. http://dx.doi.org/10.3390/en15082908.
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For large-scale and sustainable water electrolysis, it is of great significance to develop cheap and efficient electrocatalysts that can replace platinum. Currently, it is difficult for most catalysts to combine high activity and stability. To solve this problem, we use cobalt to regulate the electronic structure of ruthenium to achieve high activity, and use carbon matrix to protect alloy nanoparticles to achieve high stability. Herein, based on the zeolitic imidazolate frameworks (ZIFs), a novel hybrid composed of RuCo alloy nano-particles and N-doped carbon was prepared via a facile pyrolysis-displacement-sintering strategy. Due to the unique porous structure and multi-component synergy, the optimal RuCo500@NC750 material in both acidic and alkaline media exhibited eminent HER catalytic activity. Notably, the 3-RuCo500@NC750 obtained a current density of 10 mA cm−2 at 22 mV and 31 mV in 0.5 M H2SO4 and 1.0 M KOH, respectively, comparable to that of the reference Pt/C catalyst. Furthermore, the Tafel slopes of the catalyst are 52 mV Dec−1 and 47 mV Dec−1, respectively, under acid and alkali conditions, and the catalyst has good stability, indicating that it has broad application prospects in practical electrolytic systems. This work contributes to understanding the role of carbon-supported polymetallic alloy in the electrocatalytic hydrogen evolution process, and provides some inspiration for the development of a high efficiency hydrogen evolution catalyst.
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Huth, Michael, Fabrizio Porrati, Peter Gruszka, and Sven Barth. "Temperature-Dependent Growth Characteristics of Nb- and CoFe-Based Nanostructures by Direct-Write Using Focused Electron Beam-Induced Deposition." Micromachines 11, no. 1 (December 25, 2019): 28. http://dx.doi.org/10.3390/mi11010028.
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Focused electron and ion beam-induced deposition (FEBID/FIBID) are direct-write techniques with particular advantages in three-dimensional (3D) fabrication of ferromagnetic or superconducting nanostructures. Recently, two novel precursors, HCo 3 Fe(CO) 12 and Nb(NMe 3 ) 2 (N-t-Bu), were introduced, resulting in fully metallic CoFe ferromagnetic alloys by FEBID and superconducting NbC by FIBID, respectively. In order to properly define the writing strategy for the fabrication of 3D structures using these precursors, their temperature-dependent average residence time on the substrate and growing deposit needs to be known. This is a prerequisite for employing the simulation-guided 3D computer aided design (CAD) approach to FEBID/FIBID, which was introduced recently. We fabricated a series of rectangular-shaped deposits by FEBID at different substrate temperatures between 5 ° C and 24 ° C using the precursors and extracted the activation energy for precursor desorption and the pre-exponential factor from the measured heights of the deposits using the continuum growth model of FEBID based on the reaction-diffusion equation for the adsorbed precursor.
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Peng, Ruochen, Qu Zhou, and Wen Zeng. "First-Principles Insight into Pd-Doped C3N Monolayer as a Promising Scavenger for NO, NO2 and SO2." Nanomaterials 11, no. 5 (May 12, 2021): 1267. http://dx.doi.org/10.3390/nano11051267.
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The adsorption and sensing behavior of three typical industrial toxic gases NO, NO2 and SO2 by the Pd modified C3N monolayer were studied in this work on the basic first principles theory. Meanwhile, the feasibility of using the Pd doped C3N monolayer (Pd-C3N) as a sensor and adsorbent for industrial toxic gases was discussed. First, the binding energies of two doping systems were compared when Pd was doped in the N-vacancy and C-vacancy sites of C3N to choose the more stable doping structure. The result shows that the doping system is more stable when Pd is doped in the N-vacancy site. Then, on the basis of the more stable doping model, the adsorption process of NO, NO2 and SO2 by the Pd-C3N monolayer was simulated. Observing the three gases adsorption systems, it can be found that the gas molecules are all deformed, the adsorption energy (Ead) and charge transfer (QT) of three adsorption systems are relatively large, especially in the NO2 adsorption system. This result suggests that the adsorption of the three gases on Pd-C3N belongs to chemisorption. The above conclusions can be further confirmed by subsequent deformable charge density (DCD) and density of state (DOS) analysis. Besides, through analyzing the band structure, the change in electrical conductivity of Pd-C3N after gas adsorption was studied, and the sensing mechanism of the resistive Pd-C3N toxic gas sensor was obtained. The favorable adsorption properties and sensing mechanism indicate that the toxic gas sensor and adsorbent prepared by Pd-C3N have great application potential. Our work may provide some guidance for the application of a new resistive sensor and gas adsorbent Pd-C3N in the field of toxic gas monitoring and adsorption.
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Platonov, Vadim B., Marina N. Rumyantseva, Alexander S. Frolov, Alexey D. Yapryntsev, and Alexander M. Gaskov. "High-temperature resistive gas sensors based on ZnO/SiC nanocomposites." Beilstein Journal of Nanotechnology 10 (July 26, 2019): 1537–47. http://dx.doi.org/10.3762/bjnano.10.151.
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Increasing requirements for environmental protection have led to the need for the development of control systems for exhaust gases monitored directly at high temperatures in the range of 300–800 °C. The development of high-temperature gas sensors requires the creation of new materials that are stable under these conditions. The stability of nanostructured semiconductor oxides at high temperature can be enhanced by creating composites with highly dispersed silicon carbide (SiC). In this work, ZnO and SiC nanofibers were synthesized by electrospinning of polymer solutions followed by heat treatment, which is necessary for polymer removal and crystallization of semiconductor materials. ZnO/SiC nanocomposites (15–45 mol % SiC) were obtained by mixing the components in a single homogeneous paste with subsequent thermal annealing. The composition and microstructure of the materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The electrophysical and gas sensing properties of the materials were investigated by in situ conductivity measurements in the presence of the reducing gases CO and NH3 (20 ppm), in dry conditions (relative humidity at 25 °C RH25 = 0) and in humid air (RH25 = 30%) in the temperature range 400–550 °C. The ZnO/SiC nanocomposites were characterized by a higher concentration of chemisorbed oxygen, higher activation energy of conductivity, and higher sensor response towards CO and NH3 as compared with ZnO nanofibers. The obtained experimental results were interpreted in terms of the formation of an n–n heterojunction at the ZnO/SiC interface.
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Baborska-Narożny, M., M. Laska, N. Fidrów-Kaprawy, and M. Malyszko. "Circadian winter thermal profiles and thermal comfort in historical housing — field study." Journal of Physics: Conference Series 2069, no. 1 (November 1, 2021): 012081. http://dx.doi.org/10.1088/1742-6596/2069/1/012081.
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Abstract In winter thermally inefficient building envelopes of pre-retrofit historical housing allow for ca. sevenfold higher heat loss from heated apartments than the new built housing in Poland. As a result space heating in pre-retrofit tenements is regarded to be highly energy demanding and costly if the internal temperatures were to be kept on average at standard 20 °C assumed in building regulations. In this field study, carried out in January-March 2020, we investigated circadian thermal profiles and the associated thermal comfort in historical tenements both pre-and post-retrofit. The 16 apartments participating in our research were equipped with heating systems prevalent in Polish urban historical buildings, i.e. solid fuel stoves, electric heating, district-supplied central heating, or individual gas boilers. The former systems provided intermittent local heating while the latter central heating with thermostats. Our research comprised spot check multi-parameter measurements and continuous monitoring of the thermal environment, together with a longitudinal thermal comfort questionnaire survey (N=.2539), energy consumption analysis and semi-structured interviews with the residents. The differences detected in average (12.6°C) and range (up to 5.0°C) of diurnal temperatures did not explain the thermal comfort survey results on individual thermal sensations and preferences. What proved more important for the residents was the time of day when the maximum or minimum temperatures occurred and their perceived control over temperature and the cost associated with heating. Accordingly, we identified a need for further studies investigating the link between domestic thermal comfort and satisfaction with the usability of the heating system and control over the cost of heating.
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Nędzarek, Arkadiusz, Małgorzata Bonisławska, Agnieszka Tórz, Adam Tański, and Krzysztof Formicki. "Effect of Filter Medium on Water Quality during Passive Biofilter Activation in a Recirculating Aquaculture System for Oncorhynchus mykiss." Energies 15, no. 19 (September 20, 2022): 6890. http://dx.doi.org/10.3390/en15196890.
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High-performance biofilters for water purification in recirculating aquaculture systems (RAS) ensure the safety of cultures of highly nutritious fish. As the most critical step in the functioning of biofilters is their activation, the objective of this study was to evaluate the suitability of commercial artificial media, namely RK Plast (BR-1), Mutag-BioChip30 (BR-2), and LevaPor (BR-3), for the passive activation of biofilters used in rainbow trout farming. Changes in NH4+-N, NO2−-N, NO3− -N, phosphorus, and carbon concentrations were analyzed. In the first period, an increase in NH4+-N concentration was recorded, before an increase in NO2−-N concentration (maximum concentrations ranged 0.728–1.290 and 0.982–5.198 mg N dm−3, respectively), followed by a reduction and stabilization to a level safe for the fish (both below 0.100 mg N dm−3). Concurrently, a steady increase in NO3−-N concentration was noted, with a maximum concentration between 6.521 and 7.326 mg N dm−3. Total phosphorus and total carbon ranged from 0.423 to 0.548 mg P dm−3, and from 43.8 to 45.2 mg C dm−3. The study confirmed the feasibility of using the tested artificial biofilter media for rainbow trout farming in RAS with passive biofilter activation. Biofilter activation efficiency was highest for the media with the highest specific surface area (BR-2 and BR-3). The removal of ammonium nitrogen and nitrite nitrogen was above 90%. Nitrogen biotransformation was not limited by phosphorus or carbon concentrations.
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Rehman, Iqra, Muhammad Riaz, Sajid Ali, Muhammad Saleem Arif, Shafaqat Ali, Mohammed Nasser Alyemeni, and Abdulaziz Abdullah Alsahli. "Evaluating the Effects of Biochar with Farmyard Manure under Optimal Mineral Fertilizing on Tomato Growth, Soil Organic C and Biochemical Quality in a Low Fertility Soil." Sustainability 13, no. 5 (March 2, 2021): 2652. http://dx.doi.org/10.3390/su13052652.
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Biochar amendments are widely recognized to improve crop productivity and soil biogeochemical quality, however, their effects on vegetable crops are less studied. This pot study investigated the effects of cotton stick, corncob and rice straw biochars alone and with farmyard manure (FYM) on tomato growth, soil physico–chemical and biological characteristics, soil organic carbon (SOC) content and amount of soil nutrients under recommended mineral fertilizer conditions in a nutrient-depleted alkaline soil. Biochars were applied at 0, 1.5 and 3% (w/w, basis) rates and FYM was added at 0 and 30 t ha−1 rates. Biochars were developed at 450 °C pyrolysis temperature and varied in total organic C, nitrogen (N), phosphorus (P) and potassium (K) contents. The results showed that biochars, their amounts and FYM significantly improved tomato growth which varied strongly among the biochar types, amounts and FYM. With FYM, the addition of 3% corncob biochar resulted in the highest total chlorophyll contents (9.55 ug g−1), shoot (76.1 cm) and root lengths (44.7 cm), and biomass production. Biochars with and without FYM significantly increased soil pH, electrical conductivity (EC) and cation exchange capacity (CEC). The soil basal respiration increased with biochar for all biochars but not consistently after FYM addition. The water-extractable organic C (WEOC) and soil organic C (SOC) contents increased significantly with biochar amount and FYM, with the highest SOC found in the soil that received 3% corncob biochar with FYM. Microbial biomass C (MBC), N (MBN) and P (MBP) were the highest in corncob biochar treated soils followed by cotton stick and rice straw biochars. The addition of 3% biochars along with FYM also showed significant positive effects on soil mineral N, P and K contents. The addition of 3% corncob biochar with and without FYM always resulted in higher soil N, P and K contents at the 3% rate. The results further revealed that the positive effects of biochars on above-ground plant responses were primarily due to the improvements in below-ground soil properties, nutrients’ availability and SOC; however, these effects varied strongly between biochar types. Our study concludes that various biochars can enhance tomato production, soil biochemical quality and SOC in nutrient poor soil under greenhouse conditions. However, we emphasize that these findings need further investigations using long-term studies before adopting biochar for sustainable vegetable production systems.