775 results
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2. Strain in Halide Perovskite Solar Cells: Origins, Impacts, and Regulation.
- Author
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Guo, He, Li, Zi Jia, Kim, Soo Chan, Han, Gill Sang, and Jung, Hyun Suk
- Subjects
SOLAR cells ,CHEMICAL decomposition ,PEROVSKITE ,THIN films ,PHASE transitions ,SOLAR technology - Abstract
Perovskite solar cells have made significant progress in the past decade, demonstrating promising potential for next‐generation solar technology. However, the strain‐induced intrinsic instability of mixed‐halide perovskites poses a significant obstacle to their widespread commercialization. Relaxation of the perovskite lattice strain is a crucial approach for enhancing photovoltaic performance and broadening their application potential. In this study, the authors conduct an analysis of strain progression in perovskite thin films, examining its impact on the physical properties of perovskites and the performance of perovskite solar cells. Furthermore, they explore its influence on device stability from the perspectives of phase transitions, chemical decomposition, and mechanical fragility. Additionally, they provide a summary of key advancements in strain‐relaxation strategies and offer design principles and synthetic approaches to address the issue of lattice strain in perovskites. This paper is intended to lay the groundwork for the theoretical development of effective strain‐relaxation methods, moving beyond sole reliance on empirical optimization. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Decomposition reaction kinetics of double‐base propellant catalyzed with graphene oxide–copper oxide nanocomposite.
- Author
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Louafi, Elamine, Boulkadid, Moulai Karim, Belgacemi, Raouf, Touidjine, Sabri, Akbi, Hamdane, Belkhiri, Samir, and Benaliouche, Fouad
- Subjects
CHEMICAL decomposition ,CHEMICAL kinetics ,GRAPHENE oxide ,COPPER oxide ,PROPELLANTS ,NANOCOMPOSITE materials - Abstract
The purpose of this paper is the investigation of the catalytic effect of graphene oxide–copper oxide nanocomposite (GCNC) on the thermal comportment and decomposition reaction kinetics of a double‐base propellant (DBP) formulation. Differential scanning calorimetry (DSC) was used to conduct the thermal analysis. Using well‐known iso‐conversional kinetics methods, namely, Vyazovkin's nonlinear integral with compensatory effect (VYA/CE), Kissinger–Akahira–Sunose (KAS), and Flynn–Wall–Ozawa (FWO), the thermokinetic parameters for the investigated propellant, including activation energy and frequency factor, were estimated. Additionally, based on the results obtained from the kinetic analysis, the critical ignition temperature was calculated. The results showed that after the addition of GCNC, the activation energy barrier is lowered by 18%, and the critical ignition temperature is reduced. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Comparative Analysis of Two Online Identification Algorithms in a Fuel Cell System.
- Author
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Kandidayeni, M., Macias, A., Amamou, A. A., Boulon, L., and Kelouwani, S.
- Subjects
FUEL cells ,ENERGY management ,CHEMICAL decomposition ,TEMPERATURE ,ALGORITHMS - Abstract
Abstract: Output power of a fuel cell (FC) stack can be controlled through operating parameters (current, temperature, etc.) and is impacted by ageing and degradation. However, designing a complete FC model which includes the whole physical phenomena is very difficult owing to its multivariate nature. Hence, online identification of a FC model, which serves as a basis for global energy management of a fuel cell vehicle (FCV), is considerably important. In this paper, two well‐known recursive algorithms are compared for online estimation of a multi‐input semi‐empirical FC model parameters. In this respect, firstly, a semi‐empirical FC model is selected to reach a satisfactory compromise between computational time and physical meaning. Subsequently, the algorithms are explained and implemented to identify the parameters of the model. Finally, experimental results achieved by the algorithms are discussed and their robustness is investigated. The ultimate results of this experimental study indicate that the employed algorithms are highly applicable in coping with the problem of FC output power alteration, due to the uncertainties caused by degradation and operation condition variations, and these results can be utilized for designing a global energy management strategy in a FCV. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
5. Winter cover crop legacy effects on litter decomposition act through litter quality and microbial community changes.
- Author
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Barel, Janna M., Kuyper, Thomas W., Paul, Jos, Boer, Wietse, Cornelissen, Johannes H. C., De Deyn, Gerlinde B., and Cheng, Lei
- Subjects
NITROGEN in soils ,CHEMICAL decomposition - Abstract
Copyright of Journal of Applied Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2019
- Full Text
- View/download PDF
6. Impact of Platinum Loading on Performance and Degradation of Polymer Electrolyte Fuel Cell Electrodes Studied in a Rainbow Stack.
- Author
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Gazdzicki, P., Mitzel, J., Dreizler, A. M., Schulze, M., and Friedrich, K. A.
- Subjects
PROTON exchange membrane fuel cells ,PLATINUM ,CHEMICAL decomposition ,ELECTRIC potential ,DURABILITY - Abstract
Abstract: The paper focuses on the investigation of durability and performance of a low temperature polymer electrolyte membrane fuel cell (PEMFC) stack as a function of Pt loading in automotive test conditions. Major motivations are problems related to the need to reduce the amount of Pt in membrane electrode assemblies (MEAs) in order to make PEMFC more competitive. The particular challenge is to maintain sufficiently high performance and long‐term durability. The study shows that for cathode Pt loadings below 0.2 mg cm
−2 and for current densities exceeding 1 A cm−2 a sudden drop of performance is observed. The same threshold value is found for the increase of irreversible voltage losses which lead to an intense reduction of PEMFC durability for cathodic loadings below 0.2 mg cm−2 . Another durability issue at cathodic Pt loadings < 0.4 mg cm−2 is the acceleration of reversible degradation, which leads to a strong voltage drop during continues fuel cell operation (i.e., without a recovery interruption). [ABSTRACT FROM AUTHOR]- Published
- 2018
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7. Interpreting the replacement and richness difference components of beta diversity.
- Author
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Legendre, Pierre
- Subjects
DEVELOPMENTAL biology ,FISH communities ,ANIMAL species ,ECOSYSTEMS ,CHEMICAL decomposition ,FISH ecology ,COMPARATIVE studies - Abstract
Aim The variation in species composition among sites, or beta diversity, can be decomposed into replacement and richness difference. A debate is ongoing in the literature concerning the best ways of computing and interpreting these indices. This paper first reviews the historical development of the formulae for decomposing dissimilarities into replacement, richness difference and nestedness indices. These formulae are presented for species presence-absence and abundance using a unified algebraic framework. The indices decomposing beta play different roles in ecological analysis than do beta-diversity indices. Innovation Replacement and richness difference indices can be interpreted and related to ecosystem processes. The pairwise index values can be summed across all pairs of sites; these sums form a valid decomposition of total beta diversity into total replacement and total richness difference components. Different communities and study areas can be compared: some may be dominated by replacement, others by richness/abundance difference processes. Within a region, differences among sites measured by these indices can then be analysed and interpreted using explanatory variables or experimental factors. The paper also shows that local contributions of replacement and richness difference to total beta diversity can be computed and mapped. A case study is presented involving fish communities along a river. Main conclusions The different forms of indices are based upon the same functional numerators. These indices are complementary; they can help researchers understand different aspects of ecosystem functioning. The methods of analysis used in this paper apply to any of the indices recently proposed. Further work, based on ecological theory and numerical simulations, is required to clarify the precise meaning and domain of application of the different forms. The forms available for presence-absence and quantitative data are both useful because these different data types allow researchers to answer different types of ecological or biogeographic questions. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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8. Theoretical study on initial decomposition paths of energetic materials featuring RDX ring.
- Author
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Shang, Fangjian, Shi, Yanlin, Wang, Caifeng, Liu, Huaxin, and Lv, Meiheng
- Subjects
- *
CYCLONITE , *ACTIVATION energy , *CHEMICAL decomposition , *FUNCTIONAL groups , *QUANTUM chemistry - Abstract
The molecular properties of RDX are affected by the introduction of different functional groups, and the decomposition process of these analogues is studied in this paper. DFT method is used to study the initial decomposition reaction paths of 30 high energy materials based RDX skeleton. In the nitro cleavage reaction, the energy barrier become relatively low by introducing CH(NO2)2 or C(NO2)3 groups on the C site of the six membered ring. In the ring opening reaction, the ring opening process is easier to proceed by introducing NH2 or NHNH2 groups on the C site of the six membered ring. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. Comparison of UV‐Cl and UV‐H2O2 advanced oxidation processes in the degradation of contaminants from water and wastewater: A review.
- Author
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Farzanehsa, Mahshid, Vaughan, Liam C., Zamyadi, Arash, and Khan, Stuart J.
- Subjects
DISINFECTION by-product ,POLLUTANTS ,WATER purification ,WASTEWATER treatment ,CHEMICAL decomposition - Abstract
Applications of advanced oxidation processes (AOPs) in water and wastewater treatment have been the subject of growing interest throughout the last decade. Although UV/hydrogen peroxide (UV‐H2O2) is the most established technology among the UV‐AOPs, UV‐chlorine (UV‐Cl) is emerging as a reliable and potentially more cost‐effective alternative. Recent studies have indicated that UV‐Cl processes may be more efficient and economically favourable for the degradation of some chemicals of emerging concern from contaminated water. Moreover, in terms of the formation of disinfection by‐products (DBPs), UV‐H2O2 seems to have no superiority over UV‐Cl. This said, more investigation in the assessment of genotoxicity and cytotoxicity of DBPs is required. Additionally, more pilot‐scale and full‐scale studies are required to establish UV‐Cl as a reliable alternative to UV‐ H2O2. This paper compares UV‐Cl and UV‐H2O2 AOPs for the degradation of intractable chemicals from water and wastewater based on the practical considerations of efficiency, cost, DBP formation, kinetics and sensitivity to water matrix variability. Finally, various modelling approaches to UV‐Cl have been reviewed. This review showed that UV‐Cl is superior to UV‐H2O2 in terms of degradation efficiency and cost effectiveness and can be a robust alternative in many UV‐AOPs applications. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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10. An Analysis of Sorting and Recycling of Household Waste: A neo- Ricardian Approach.
- Author
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Hosoda, Eiji B.
- Subjects
WASTE management ,WASTE recycling ,RICARDIAN equivalence theorem ,ECONOMIC development ,CHEMICAL decomposition ,RECYCLED products - Abstract
One of the most interesting but troublesome features of daily recycling is the mixture of different types of household waste and degradation of a recycled material caused by the mixture of different types of waste. This is often seen in recycling of materials such as used papers, plastics and so on. This paper analyses this aspect, and demonstrates how the formation of prices and activity levels is made in a long-run growing economy, by means of a neo- Ricardian type of production model. It is proved that a long-run equilibrium exists under reasonable assumptions. It is also shown how the sorting rate of different types of waste affects the grade of recyclable resources as well as prices. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
11. Thermal Properties of γ‐Cyclodextrin Nitrates with Various Degrees of Nitration.
- Author
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Maksimowski, Paweł, Janson, Agnieszka, and Gołofit, Tomasz
- Subjects
CYCLODEXTRINS ,THERMAL properties ,NITRATION ,HEAT of combustion ,DIFFERENTIAL scanning calorimetry ,CHEMICAL decomposition - Abstract
The aim of this paper was to analyze the thermal properties of γ‐cyclodextrins with different degrees of nitration and to determine the kinetic parameters of their decomposition reactions. The differential scanning calorimetry was used to investigate six nitro derivatives of γ‐cyclodextrins obtained and characterized by various degrees of nitration. The tested samples differed in the number of esterified OH groups in γ‐cyclodextrins from 6.4 to 24.0 and nitrogen content from 6.3 to 14.1 %. It was concluded that the value of the heat of combustion increases with the nitrogen content and achieves the highest value (4.0 kJ/g) for nitrogen content 14.1 %. The thermal effect of decomposition was found to increase significantly and proportionally to the increased heating rate of the sample. The largest temperature shift of the decomposition process with changed heat flow rate was observed for the samples with the highest nitrogen content (13.7 % and 14.1 %). No influence of nitrogen content on the value of apparent activation energy for the obtained γ‐nitrocyclodextrins was observed, which may indicate that the initial stage of decomposition is independent from the nitrogen content. The determined kinetic parameters of the decomposition reaction make it possible to estimate the safe conditions for the synthesis, use and storage of γ‐nitrocyclodextrins and to determine parameters such as Self‐Accelerating Decomposition Temperature (SADT), Adiabatic Decomposition Temperature (ADT24). [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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12. Design of PI controller parameters of a CSI‐fed SCIM drive ensuring high damping ratio and maximum system stability.
- Author
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Tripathi, Saurabh Mani, Vaish, Rachna, and Pandey, Ashok Kumar
- Subjects
ELECTRIC motors ,AUTOMOBILE driving ,CHEMICAL decomposition ,ELECTRIC power ,HYBRID electric vehicles - Abstract
The control scheme for an electric motor drive is generally implemented by involving proportional‐integral (PI) controllers in current and speed feedback control loops. A good design of PI controller parameters has always been a challenging task for control system design engineers. This paper describes the D‐decomposition method for the design of the parameters of involved DC‐link current and speed PI controllers in closed‐loop scheme of a pulse width‐modulated, current source inverter (CSI)‐fed squirrel‐cage induction motor drive. The PI controllers ensure the stable operation of CSI‐fed induction motor in natural unstable operating region of its torque‐slip characteristic. In order to achieve smoother speed tracking performance with minimum overshoot/undershoot, the damping ratio has been pre‐specified while designing the PI controller parameters using the D‐decomposition method. Simulation results have been presented to confirm the design and have been compared with the results already published. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
13. THE DECOMPOSITION AND DYNAMICS OF INDUSTRIAL CARBON DIOXIDE EMISSIONS FOR 287 CHINESE CITIES IN 1998-2009.
- Author
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Auffhammer, Maximilian, Sun, Weizeng, Wu, Jianfeng, and Zheng, Siqi
- Subjects
CARBON dioxide mitigation ,EMISSION control ,CHEMICAL decomposition ,GREENHOUSE gases ,URBAN economics - Abstract
85% of China's GHG emissions are attributed to urban economic activities, and this share is expected to rise given China's fast urbanization process. This paper provides estimates of city-level industrial CO
2 emissions and their growth rates for all 287 Chinese prefecture-level and above cities during the years 1998-2009. We decompose the CO2 emission changes into scale, composition and technique effects. The decomposition results show that these three effects differ significantly across the three tiers of cities in China. The scale effect contributes to rising CO2 emissions, while the technique effect leads to declining CO2 emissions in all cities. The composition effect leads to increasing CO2 emissions in the third-tier cities, while it reduces CO2 emissions in the first and second-tier cities, due to the relocation of energy-intensive industries from the latter to the former type of cities. Based on these decomposition results, we identify the separate channels through which the inflow of FDI and the environmental regulations affect city-level CO2 emissions. The decomposition framework in our paper can help policy makers and scholars to better understand Chinese cities' trade-offs between economic growth and environmental goals. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
14. Irregular Time-Varying Stress Degradation Path Modeling: a Case Study on Lithium-ion Cell Degradation.
- Author
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Liu, Tianyu, Sun, Quan, Pan, Zhengqiang, Feng, Jing, and Tang, Yanzhen
- Subjects
CHEMICAL decomposition ,RELIABILITY in engineering ,TIME-varying systems ,LEAST squares - Abstract
The aim of this paper is to investigate the issue of degradation modeling and reliability assessment for products under irregular time-varying stresses. Conventional degradation models have been extensively used in the relevant literature to characterize degradation processes under deterministic stresses. However, the time-varying stress, which may affect degradation processes, widely exists in field conditions. This paper extends the general degradation-path model by considering the effects of time-varying stresses. The new degradation-path model captures influences of varying stresses on performance characteristics. A nonlinear least square method is used to estimate the unknown parameters of the proposed model. A bootstrap algorithm is adopted for computing the confidence intervals of the mean time to failure and percentiles of the failure-time distribution. Finally, a case study of lithium-ion cells is presented to validate the proposed method. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
15. Engineering Durable Superhydrophobic Photocatalyst for Oil‐Water Separation and Degradation of Chemical Pollutants.
- Author
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Zhu, Haiguang, Chen, Long, Dou, Xinyue, Liu, Yong, and Yuan, Xun
- Subjects
POLLUTANTS ,CHEMICAL decomposition ,PHOTOCATALYSTS ,WASTEWATER treatment ,CHEMICAL bonds ,POLYDIMETHYLSILOXANE ,ENVIRONMENTAL protection ,OIL spill cleanup - Abstract
Wastewater treatment, especially for those containing insoluble oils and soluble chemical pollutants, has been a major concern in the field of environmental protection. Materials integrating both hydrophobicity and photocatalytic activity are good candidates in terms of separating insoluble oils from water and photodegrading soluble chemical pollutants. However, the wide application of such materials is curtailed by their susceptible photodecomposition issue. In this paper, we report the design of a durable yet efficient hydrophobic photocatalyst by immobilizing photocatalytic titanium dioxide (TiO2) on a carbonized melamine foam (CMF) for a three‐dimensional (3D) porous structure, and subsequently coating a hydrophobic polydimethylsiloxane (PDMS) layer on TiO2 surface (CMF‐TiO2‐PDMS). The key feature of the design is that the PDMS layer could re‐graft on the TiO2 surface via forming chemical bonds with TiO2 under UV illumination, granting the resulting CMF‐TiO2‐PDMS stable hydrophobicity to durably resist photocatalytic oxidation. As expected, the as‐designed CMF‐TiO2‐PDMS photocatalyst shows excellent durability in removing insoluble organic solvents and photodegrading soluble chemical pollutants under UV illumination. This study is interesting not only because it provides a paradigm in designing durable yet efficient hydrophobic photocatalyst for wastewater treatment, but also shed lights on the design of other multifunctional materials. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
16. Additive-state-decomposition-based tracking control framework for a class of nonminimum phase systems with measurable nonlinearities and unknown disturbances.
- Author
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Quan, Quan, Cai, Kai‐Yuan, and Lin, Hai
- Subjects
CHEMICAL decomposition ,TRACKING & trailing ,NONLINEAR systems ,FIBERS ,PSYCHOLOGICAL feedback - Abstract
SUMMARY This paper aims to propose an additive-state-decomposition-based tracking control framework, based on which the output feedback tracking problem is solved for a class of nonminimum phase systems with measurable nonlinearities and unknown disturbances. This framework is to 'additively' decompose the output feedback tracking problem into two more tractable problems, namely an output feedback tracking problem for a linear time invariant system and a state feedback stabilization problem for a nonlinear system. Then, one can design a controller for each problem respectively using existing methods, and these two designed controllers are combined together to achieve the original control goal. The main contribution of the paper lies on the introduction of an additive state decomposition scheme and its implementation to mitigate the design difficulty of the output feedback tracking control problem for nonminimum phase nonlinear systems. To demonstrate the effectiveness, an illustrative example is given. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
17. The chemical degradation of the oil sludge produced from polymer flooding in offshore oilfield.
- Author
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Chen, Bin, Zhao, Lin, Duan, Ming, Yao, Meng, Fang, Shenwen, Wang, Chengsheng, and Chen, Shijia
- Subjects
CHEMICAL decomposition ,SEWAGE sludge ,OIL fields ,POLYMER flooding (Petroleum engineering) ,DIETHYLENETRIAMINE ,ACETIC acid ,POLYMER colloids - Abstract
Usually, the treatment of oil sludge produced from polymer flooding (OSPPF) in offshore oilfield needs transport and incineration. It is time‐consuming and high‐economic cost. In this paper, firstly, the OSPPF in an offshore oilfield was analyzed by IR, SEM, EDS, and XRD and its formation mechanism was discussed. Then, chemical degradation was proposed according to the formation mechanism. Mixture of H2O2 and diethylene triamine pentacetic acid (DTPA) was chosen for the chemical degradation of OSPPF. The effects of different factors on degradation rate were studied and the national condition was obtained as follows: 3 g OSPPF, 3 g kerosene, and 9 g aqueous solutions containing 5 wt% H2O2+ DTPA (H2O2:DTPA was 1:1) were mixed at 65°C for 12 hour. After the degradation, the oil in the OSPPF can be recovered and polymer gel in the OSPPF can be destroyed completely. This chemical degradation is a good choice for treatment of OSPPF in situ. In this paper, the composition and causation of OSPPF produced from one offshore oilfield was analyzed firstly and then it was treated by chemical degradation. The chemical degradation is a good choice for in situ treatment of OSPPF for the offshore oilfield. To our knowledge, this is the first study for treatment of OSPPF produced from offshore oilfield in situ by chemical degradation. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
18. On the Relationship between Classical Structure Determination and Retrosynthetic Analysis/Total Synthesis†.
- Author
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Seeman, Jeffrey I.
- Subjects
ORGANIC synthesis ,MOLECULAR structure ,CHEMICAL decomposition ,CHEMICAL reactions ,ANALYTICAL chemistry - Abstract
Abstract: The relationship between classical structure determination and retrosynthetic analysis combined with total synthesis is examined in detail. The chemical degradation steps in the former are the counterparts of the retrosynthetic steps in the latter. And the gedankenexperiment, also known as “paper chemistry,” working forward and solving the structure from the degradation data, is the counterpart of the experimental forward steps in a total synthesis. The wide use of genealogic‐like “trees” to organize and illustrate many reaction sets in organic chemistry is discussed. Excerpts from the writings of Sir Robert Robinson, R. B. Woodward, and Carl Djerassi reveal historically important insights about these activities in the 1940s–1960s. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
19. Identification of decomposition reactions for HMDSO organosilicon using quantum chemical calculations.
- Author
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Huang, Yaosong, Chen, Yugong, and Zhou, Mingfei
- Subjects
CHEMICAL decomposition ,ACTIVATION energy ,DENSITY functional theory ,FLAME - Abstract
Hexamethyldisiloxane [HMDSO, (CH3)3‐SiOSi‐(CH3)3] is an important precursor for SiO2 formation during flame‐based silica material synthesis. As a result, HMDSO reactions in flame have been widely investigated experimentally, and many results have indicated that HMDSO decomposition reactions occur very early in this process. In this paper, quantum chemical calculations are performed to identify the initial decomposition of HMDSO and its subsequent reactions using the density functional theory at the level of B3LYP/6‐311+G (d, p). Four reaction pathways—(a) SiO bond dissociation of HMDSO, (b) SiC bond dissociation of HMDSO, (c) dissociation and recombination of SiO and SiC bonds, and (d) elimination of a methane molecule from HMDSO—have been examined and identified. From the results, it is found that the barrier of 84.38 kcal/mol and SiO bond dissociation energy of 21.55 kcal/mol are required for the initial decomposition reaction of HMDSO in the first pathway, but the highest free energy barrier (100.69 kcal/mol) is found in the third reaction pathway. By comparing the free energy barriers and reaction rate constants, it is concluded that the most possible initial decomposition reaction of HMDSO is to eliminate the CH3 radical by SiC bond dissociation. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
20. Facile crosslinking of polybutadienes via triazoline heterocyclics: Deciphering mechanism and structural‐property relations.
- Author
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Sasidharakurup, Reshmi, Kunduchi Periya, Vijayalakshmi, Chinthalapalli, Srinivas, Thomas, Deepthi, and Nair, C. P. Reghunadhan
- Subjects
PROPELLANTS ,CHEMICAL yield ,SOLID propellants ,CHEMICAL decomposition ,ADDITION reactions ,DENSITY functional theory - Abstract
Chain‐end functionalized polybutadiene polymers have widespread application in composite solid propellants (CSP). Curing of these polymers is effected using the reactions at the terminal groups with isocyanates or aziridines if the functional groups are hydroxyl or carboxyl respectively. The high toxicity of isocyanates and aziridines demands alternate cure methods. A facile reaction, devoid of any side reactions is the most desirable one. The large number of double bonds in polybutadienes is favorable for 1, 3 ‐dipolar addition reaction with an azide to yield triazolines. The mechanistic aspects of the uncatalyzed and copper‐mediated azide‐alkene reaction have not been explored previously. The present study focuses on elucidation of the reaction using model compounds of polybutadiene namely trans 3‐hexene, cis‐3 hexene and 3‐methyl pentene which mimic the microstructure of polybutadienes. The paper presents the elucidation of the mechanism using density functional theory (DFT) calculations, detailed reaction pathway and its experimental validation using Fourier transform infrared (FTIR) spectroscopy and 13C nuclear magnetic resonance (NMR) spectroscopy. DFT studies indicate that the activation barrier of 63.8 to 85 kJ/mol for the uncatalyzed reaction. In the copper catalyzed reaction, it diminishes to the range of 18.1 to 33.0 kJ/mol. The thermal decomposition aspects of the cured triazoline system were evaluated using thermogravimetric‐mass spectrometer (TG‐MS). The binder undergoes single stage decomposition in the temperature regime of 278°C‐534°C which is lower than that reported for polyurethane‐polybutadienes. The decomposition reaction yields more volatile products like nitrogen, carbon dioxide, 1,4 butadiene and 4‐vinylcyclohexene, conducive for propellant applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
21. Carbon Nanotubes as a Solid Acid Fuel Cell Cathode Material: Insights into In Operando Functional Stability.
- Author
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Naumov, Olga, Lohmann, Felix P., Abel, Bernd, and Varga, Aron
- Subjects
FUEL cells ,ELECTROCATALYSTS ,MULTIWALLED carbon nanotubes ,CHEMICAL decomposition ,OXYGEN reduction - Abstract
Carbon nanomaterials, such as carbon nanotubes and graphene doped with heteroatoms, have drawn much attention, owing to their activity as a fuel cell electrocatalyst. This discovery is very important, as the wide application of low- and intermediate-temperature fuel cells is partly hindered by the need for precious-metals, such as platinum, as the electrocatalyst. Here, we report multi-walled carbon nanotubes (MWCNTs) as the active electrode component for the oxygen reduction reaction (ORR) in solid acid fuel cells (SAFCs) and their in operando changes of surface chemistry and structure. We show, for the first time with fuel cell measurements, the effective (time-dependent) electrocatalytic behavior of MWCNTs in SAFC cathodes. For all measurements, the MWCNTs were platinum free and were not doped with heteroatoms during or after the synthesis. AC impedance spectroscopy of the electrochemical cells, MWCNT|CsH
2 PO4 |MWCNT, with and without a DC bias, were performed and the long-term stability was evaluated over a 20 day period. Scanning electron microscopy, Raman, and XPS spectroscopy, before and after the electrochemical measurements, show significant changes in the surface chemistry and structure of the MWCNTs. We observe an increase in the surface oxygen concentration and an increased electrochemical activity. However, this active state is transient in nature, as other chemical degradation processes become more dominant. We conclude that carbon nanomaterials are promising as electrochemically active SAFC materials; however, challenges with stability need to be overcome for a realistic application. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
22. Defining the radiation chemistry during liquid cell electron microscopy to enable visualization of nanomaterial growth and degradation dynamics.
- Author
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WOEHL, T.J. and ABELLAN, P.
- Subjects
NANOSTRUCTURED materials ,CHEMICAL decomposition ,SOLUTION (Chemistry) ,RADIOLYSIS ,NUCLEATION ,RADIATION chemistry - Abstract
Copyright of Journal of Microscopy is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2017
- Full Text
- View/download PDF
23. A Novel Process for CO2 Capture by Using Sodium Metaborate, Part II: Carbonation Reaction and Kinetic Studies.
- Author
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Kibar, Murat Efgan and Akin, Ayşe Nilgün
- Subjects
CARBONATION (Chemistry) ,CHEMICAL kinetics ,SODIUM metabolism ,CHEMICAL decomposition ,ACTIVATION energy - Abstract
ABSTRACT In Part II of this two-part series of papers, optimization of carbonation reaction with sodium metaborate and kinetics of the reaction are studied and compared to the structural properties, which were reported in Part I. This paper presents a comprehensive study on the optimization of reaction conditions and determination of reaction parameters of sodium metaborate (NaBO
2 ) and carbon dioxide (CO2 ). Both hydrated and dehydrated forms of NaBO2 have high sorption capacities of CO2 up to 400°C. Decomposition of the products starts beyond 400°C and completes at 600°C. The shrinking core model is used to explain the kinetics of the noncatalytic heterogeneous reaction. The reaction progresses in two stages: one is surface reaction controlled and the other is diffusion controlled. The apparent activation energy and preexponential factor for reaction-controlled and diffusion-controlled regions are calculated as 11.8 kJ/mol and 3.5 × 106 cm2 /min and 18.2 kJ/mol and 6.5 × 10−5 cm2 /min, respectively. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
24. Thermal decomposition of ammonium nitrate.
- Author
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Babrauskas, Vytenis and Leggett, David
- Subjects
AMMONIUM nitrate ,EXPLOSIVES ,CHEMICAL decomposition ,ROCKET fuel ,POLLUTANTS ,OXIDIZING agents - Abstract
Summary: The thermal decomposition reactions of ammonium nitrate (AN) are reviewed. Both neat AN and AN containing various contaminants are examined, however quantitative kinetics results are not encompassed. Also not included is the performance of AN as the oxidizer in rocket propellants or in explosives such as ANFO. The review is intended to be the most comprehensive review of decomposition reactions of AN since Berthelot's treatise of 1892. Despite hundreds of papers on the topic that have appeared in the intervening years, understanding of decomposition mechanisms remains only modestly more complete than it was in Berthelot's day. However, some additional reaction steps and mechanisms have been identified and these are discussed. Explosions of AN most commonly involve fire as the proximate cause, yet chemical‐mechanism research on the topic is nil. A modest number of studies have explored the potentiation of AN decomposition by organic contaminants. These have, thus far, not produced guidance useful for promoting of safety from fire‐related causes. Contamination from inorganic sources, notably chlorides is better understood and some mechanisms have been studied. The UN classification of AN as an oxidizer, instead of as an explosive, should not be interpreted literally, since AN has been associated with numerous detonation disasters. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
25. Fire suppression performance of a new type of composite superfine dry powder.
- Author
-
Li, Hangchen, Feng, Li, Du, Dexu, Guo, Xinxin, Hua, Min, and Pan, Xuhai
- Subjects
POWDERS ,FIREFIGHTING ,CHEMICAL processes ,PARTICLE analysis ,DIFFERENTIAL scanning calorimetry ,CHEMICAL decomposition - Abstract
Summary: To enhance the performance of existing dry powders and ensure process security, a new type of dry powder based on ammonium dihydrogen phosphate (NH4H2PO4) was prepared. The prepared composite superfine dry powder was denoted as NH4H2PO4/zeolite composite in this paper. The effectiveness of commercial ABC dry powder, superfine dry powder, and the NH4H2PO4/zeolite composite in fire suppression were compared in a small‐sized fire‐extinguishing chamber. Laboratory‐scale tests showed that the NH4H2PO4/zeolite composite had considerably superior fire‐extinguishing efficiency to that of commercial ABC dry powder and superfine dry powder, along with shorter average extinguishing time and less average mass of powders consumed. In addition, the NH4H2PO4/zeolite composite also displayed much improved toxic gas suppression ability. The physical and chemical characteristics of commercial ABC dry powder, superfine dry powder, and the NH4H2PO4/zeolite composite were characterized using a range of techniques of laser particle size analysis, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Based on the analysis results, the improved fire suppression performance of the NH4H2PO4/zeolite composite can be ascribed to smaller particle size, larger surface area, and a special chemical decomposition process. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
26. Gas Releasing Mechanism of LLM‐105 Using Two‐Dimensional Correlation Infrared Spectroscopy.
- Author
-
Xiao, Qian, Sui, Heliang, Yu, Qian, Chen, Jie, Yin, Ying, and Ju, Xin
- Subjects
CHEMICAL decomposition ,CHEMICAL reactions ,GASES ,WATER - Abstract
In this paper, a sealed in‐situ reaction system and infrared spectroscopy (IR) were used to study the gas releasing mechanism of 2,6‐diamino‐3,5‐dinitropyrazine‐1‐oxide (LLM‐105) at different temperatures. Three characteristic stages of LLM‐105 during the heating process to 400 °C were detected by the moving‐window two‐dimensional correlation spectroscopy (MW2D). Two‐dimensional correlation infrared spectroscopy (2DCOS) was employed to examine changes of gas concentration in the sealed system at each stage. We found that in the first stage, LLM‐105 first released H2O and NH3. In the second stage, the decomposition is intensified, the explosive molecule first undergoes the decomposition reaction of releasing H2O, and CO2, subsequently chemical reaction producing several nitrogen gases, such as NO, N2O, HCN, NO2 and NH3. In the third stage, the decomposition process mainly releases CO2 and NH3, and the concentrations of HCN and NO2 decreased gradually. 2DCOS proven to be a very sensitive method for detecting thermal decomposition mechanisms and monitoring gas changes in sealed system. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
27. Unitarily invariant decomposition of arbitrary Hermitian matrices of physical interest.
- Author
-
Alcoba, Diego R.
- Subjects
CHEMICAL decomposition ,MATRICES (Mathematics) ,HERMITIAN forms - Abstract
Copyright of International Journal of Quantum Chemistry is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2004
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- View/download PDF
28. Influence of Gas Mixture and Temperature on AP-CVD Synthesis of Graphene on Copper Foil.
- Author
-
Kostogrud, Ilya A., Trusov, Konstantin V., and Smovzh, Dmitry V.
- Subjects
GAS mixtures ,GASES at high temperatures ,HYDROGEN-ion concentration ,CHEMICAL vapor deposition ,GRAPHENE synthesis ,CHEMICAL decomposition ,COPPER surfaces ,ETCHING - Abstract
The influence of methane and hydrogen concentration as well as temperature of synthesis on the number of layers, area of coverage, and quality of graphene formed by chemical vapor deposition on copper is studied in this paper. It is shown that methane concentration primarily affects the sample coverage area. The temperature determines the number of graphene layers and the defect rate of graphene planes. The influence of hydrogen concentration is complex: low hydrogen concentrations are insufficient to induce efficient decomposition of methane on the copper surface; high concentrations of hydrogen limit nucleation of graphene layers and the formed graphene structures are subject to etching. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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- View/download PDF
29. Chemical and Textural Characterization of Iron Oxide Nanoparticles and Their Effect on the Thermal Decomposition of Ammonium Perchlorate.
- Author
-
Campos, Eunice Aparecida, Cortez Fernandes, Maria Tereza, Kawachi, Elizabete Yoshie, Sampaio de Oliveira, José Irineu, and de Cássia Lazzarini Dutra, Rita
- Subjects
IRON oxide nanoparticles ,AMMONIUM perchlorate ,CHEMICAL decomposition - Abstract
Metal oxide nanoparticles have been used as burning rate catalysts for ammonium perchlorate (AP) decomposition in composite solid propellants. Though most papers point to the efficiency of different sizes, shapes and compositions, the texture of the agglomerated particles plays an important role in the catalytic efficiency, but this aspect is not always discussed. In this paper, iron oxide and composite iron oxide/silica powders were synthesized in microemulsion systems and their effect on the decomposition of AP was investigated. X-ray diffraction (XRD) analysis and Fourier transformed infrared spectroscopy (FT-IR) showed that the synthesized powders have an amorphous to nanocrystalline pattern, with Fe
2 O3 composition. The use of different FT-IR spectroscopic techniques - transmission, diffuse reflectance (DRIFT) and universal attenuated total reflectance (UATR) - allied to electron microscopy analysis allowed the characterization of the samples' surface, indicating that silicon oxide forms a thick matrix that covers the iron oxide nanoparticles. Adsorption of N2 , light scattering and electron microscopy pointed that all samples are formed by mesoporous agglomerated nanoparticles containing micropores indicating that silicon oxide forms a thick matrix that covers the iron oxide nanoparticles. Adsorption of N2 , pointed that all samples show different microstructures and light scattering indicated results refer to agglomerated particles. Finally, the catalytic effect of the samples on the decomposition of AP was evaluated by thermogravimetric analysis coupled to differential thermal analysis (TG/DTA), showing that only the high temperature decomposition step of AP was affected by the catalyst, shifting to lower temperatures the higher the surface area of the synthesized iron oxide sample, regardless of the presence of the silica matrix. [ABSTRACT FROM AUTHOR]- Published
- 2015
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- View/download PDF
30. Time‐lapse laboratory tests to monitor multiple phases of DNAPL in a porous medium.
- Author
-
Orlando, Luciana and Palladini, Lucia
- Subjects
SOIL pollution ,HYDROFLUOROETHERS ,CHEMICAL decomposition ,TRICHLOROETHYLENE ,GROUNDWATER - Abstract
A soil contaminated by dense non‐aqueous phase liquids generally exhibits variation of electrical permittivity and resistivity over time. In this paper, we relate photo images with results of electrical resistivity tomography, induced polarization tomography, and ground‐penetrating radar survey in a laboratory‐controlled test, where a cell, filled with grained‐glass beads contaminated with HFE‐7100 (hydrofluoroether) and under saturated conditions, was used. The aim was to find robust links between geophysical and physico‐chemical parameters of a contaminated soil in order to reduce the ambiguities in data interpretation. The monitoring, conducted over 100 days, shows that each geophysical method may or may not be sensitive to the multiple phases of hydrofluoroether (pure, dissolved and gaseous phases) depending on the contaminant (chemical composition, fresh, mature, etc.) and on the host enviroment. We propose some empirical relationships that allow us to quantitatively monitor the water saturation variation induced by hydrofluoroether. The photo images confirm that the pure phase of hydrofluoroether changes over time, which is probably due to biological or/and chemical variation of the contaminant. Electrical resistivity tomography results appear to be sensitive to the vast amount of pure phase of the hydrofluoroether. Induced polarization, measured in the extremely low frequency range (<25 Hz), allows detecting the pure phase of the contaminant, probably due to the decrease of water permeability and chemical degradation of the compound over time. The ground‐penetrating radar and time domain reflectometry methods based on measurements in very‐high frequency and ultra‐high frequency ranges are mainly sensitive to the water content and, as a consequence, to the replacement of water by pure and gaseous phases of hydrofluoroether. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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- View/download PDF
31. PID Effect of c-Si Modules: Study of Degradation and Recovery to More Closely Mimic Field Behavior.
- Author
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Jaeckel, Bengt, Cosic, Marijo, and Arp, Juergen
- Subjects
CHEMICAL decomposition ,ELECTRIC potential ,SILICON crystals ,POLARITY (Chemistry) ,PHOTOVOLTAIC power generation - Abstract
Recent research demonstrates several failure modes of photovoltaic modules operating under high electric potentials. In crystalline-silicon modules, the predominant failure mode is potential-induced degradation (PID), causing dramatic power losses in systems under high voltage and critical polarity. Environmental conditions highly influence the degradation behavior. The ability to reproduce field observation in the laboratory is challenging and not all stressors can be checked simultaneously. PID and its root cause are not fully understood, but we know several mechanisms are working simultaneously and at varying rates. The main mechanisms are degradation, characterized by ion diffusion and cell shunting, and recovery, driven by temperature, voltage, and potential. Most studies have focused on simulating module degradation using a constant set of parameters. However, field exposure to high voltage is variable, measured by the hour. In 2012, Nagel presented a module stability test with varying environmental conditions, notably temperature. To investigate PID remedies, this research develops a testing procedure that reproduces field observations while understanding that some modules do not degrade in real PV installations under high potentials. Conductive foil is applied to the front side of the module and voltage cycling is introduced to examine potential-induced degradation and potential-induced recovery behavior. The relationship between the two defines a PID stability criterion. Results show general PID sensitivity and suitable remedies for PID affected systems. PID recovery and protection solutions include applying recovery potential at night, and potential shifting, which regulates potential for the module string. This paper explores possible degradation mechanisms, recovery of module output power and PID stability criteria. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
32. The Role of Oxygen in the Degradation of Methylammonium Lead Trihalide Perovskite Photoactive Layers.
- Author
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Aristidou, Nicholas, Sanchez-Molina, Irene, Chotchuangchutchaval, Thana, Brown, Michael, Martinez, Luis, Rath, Thomas, and Haque, Saif A.
- Subjects
OXYGEN ,METHYLAMMONIUM ,PEROVSKITE ,CHEMICAL decomposition ,PHOTOACTIVATION ,MOLECULAR probes ,SUPEROXIDES - Abstract
In this paper we report on the influence of light and oxygen on the stability of CH
3 NH3 PbI3 perovskite-based photoactive layers. When exposed to both light and dry air the mp-Al2 O3 /CH3 NH3 PbI3 photoactive layers rapidly decompose yielding methylamine, PbI2 , and I2 as products. We show that this degradation is initiated by the reaction of superoxide (O2 - ) with the methylammonium moiety of the perovskite absorber. Fluorescent molecular probe studies indicate that the O2 - species is generated by the reaction of photoexcited electrons in the perovskite and molecular oxygen. We show that the yield of O2 - generation is significantly reduced when the mp-Al2 O3 film is replaced with an mp-TiO2 electron extraction and transport layer. The present findings suggest that replacing the methylammonium component in CH3 NH3 PbI3 to a species without acid protons could improve tolerance to oxygen and enhance stability. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
33. Experimental Investigation into a Novel Modular PEMFC Fuel Cell Stack.
- Author
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Scott, P., Bhinder, F., Chen, Y., and Calay, R.
- Subjects
ELECTROCHEMISTRY ,PROTON exchange membrane fuel cells ,GRAVIMETRIC analysis ,VOLUMETRIC analysis ,FAULT tolerance (Engineering) ,CHEMICAL decomposition - Abstract
The polymer electrolyte membrane fuel cell (PEMFC), despite being regarded as an ideal replacement to the internal combustion engine, is still not an economically attractive prime-mover due to a number of key challenges that have yet to be fully resolved; such as degradation to cell components resulting in inadequate lifetimes, specialized manufacturing processes, and poor gravimetric/volumetric energy densities. This paper presents a stack concept which replaces the conventional bipolar plate (BPP), a component that is responsible for a large proportion of stack cost and volume in traditional fuel cell stack designs. The stack architecture compromises of active and passive components which are suited to mass manufacture and maintain functionality that the BPP fulfilled. Furthermore, the design allows the implementation of a fault tolerant system (FTS) which can bypass faulty cells while still ensuring electrical output. The stack architecture is presented and characterized over a number of operating scenarios. The experimental studies suggest that the performance of the new design is similar to that of traditional stacks over a number of operating conditions despite the removal of the BPP and the FTS continued to operate at a desired operating criterion despite the loss of a cell within the stack [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
34. SAXS Analysis of Catalyst Degradation in High Temperature PEM Fuel Cells Subjected to Accelerated Ageing Tests.
- Author
-
Valle, F., Zuliani, N., Marmiroli, B., Amenitsch, H., and Taccani, R.
- Subjects
FUEL cells ,CHEMICAL decomposition ,PHOSPHORIC acid ,SYNCHROTRONS ,CATALYSTS - Abstract
The loss in performance during fuel cell operation is one of the critical factors that hamper fuel cells commercialization. This paper presents a research activity related to high temperature polymer electrode membrane fuel cell (HT-PEMFC) degradation. The aim of the study is to investigate catalyst degradation of membrane electrode assemblies (MEAs) subjected to load cycles. Two HT-PEM MEAs have been subjected to accelerated ageing tests based on load cycling. The cycles profile has been chosen in order to enhance catalyst degradation. Both the tests show a fuel cell performance loss lower than 30mV after 100,000 cycles at 600 mA cm
-2 . In order to analyze the catalyst evolution, synchrotron small angle X-ray scattering (SAXS) has been employed. The catalyst degradation of the two conditioned samples has been compared with the data obtained from a new MEA that has been used as reference sample. The SAXS results showed a mean size increase of the platinum nanoparticles up to the 100%. [ABSTRACT FROM AUTHOR]- Published
- 2014
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- View/download PDF
35. An Ultradurable and Uniform Cu Electrode by Blending Carbon Nanotube Fillers in Copper‐Based Metal–Organic Decomposition Ink for Flexible Printed Electronics.
- Author
-
Seong, Kwang‐dong, Kim, Jong Min, Kang, Jeongmin, Hwang, Minsik, Lee, Chaedong, and Piao, Yuanzhe
- Subjects
CARBON nanotubes ,CHEMICAL decomposition ,PRINTED electronics ,MULTIWALLED carbon nanotubes ,COPPER electrodes ,WEARABLE technology - Abstract
Abstract: Cu‐based metal–organic decomposition (MOD) ink is widely studied for printed electronics owing to its cost‐effectiveness and low‐temperature processing. The main purpose of using a low‐temperature processible Cu MOD ink is to fabricate flexible wearable devices. However, most researches are focused on enhancing the uniformity and conductivity of the formed electrode rather than increasing the durability. This paper presents an ultradurable and uniform Cu flexible electrode using a multiwalled carbon nanotube (MWCNT) filler‐blended Cu MOD ink. This MOD ink is synthesized through a facile sonication‐based mixing method. The MWCNT enhances not only the uniformity of the Cu electrode by providing a heterogeneous nucleation site but also the durability of the electrode due to mechanical robustness of MWCNT. With an optimum MWCNT content (1.0 wt%), the Cu/MWCNT film exhibits a resistivity of 25.31 µΩ cm and a resistance increase of only 1.66 times after the 150 000 times bending test with 2.6 mm of bending radius. It is expected that this Cu/MWCNT nanocomposite electrode can be used for practical applications because of its easy preparation, and its improved quality and durability. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
36. Analyses on the application of components in the phosphogypsum decomposition residue: Based on the study of migration and conversion rules of elements in the purification procedure of CaO.
- Author
-
Dai, Quxiu, Ma, Liping, Xie, Longgui, Yan, Bei, Zheng, Dalong, and Yang, Jie
- Subjects
PHOSPHOGYPSUM ,CHEMICAL decomposition ,MIGRATION reactions (Chemistry) ,CHEMICAL purification ,LIME (Minerals) - Abstract
Phosphogypsum (PG), which is a solid waste in phosphate fertilizer industry, is harmful to the environment. The pyrogenetic decomposition is mainly used in the utilization of PG, and PG decomposition residue is produced in the decomposition process. In this paper, the migration and conversion rules of elements (Al, Si, P, K, Ca, and Fe) in the purification procedure of CaO in PG decomposition residue was investigated. The acid–base method was used to purify CaO. Content and chemical forms of elements in the purification procedure were analyzed by many characterization methods such as SEM and EDS. And moreover, changes on chemical forms of elements were supported theoretically by some ternary phase diagrams, which were made by the FactSage thermodynamics software. The result showed that, the soluble silicon dioxide and the acid‐insoluble material in PG decomposition residue were effectively removed by using the acid–base method. Meanwhile, impurities separated from CaO and the CaO sample were produced in the experiment, the former can be used to produce the building materials, refractories, insulating materials in various industrial fields, and CaO sample could be used as the filler, building materials, decolorant, etc. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1020–1030, 2018 [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
37. Prescribing Functional Additives for Treating the Poor Performances of High‐Voltage (5 V‐class) LiNi0.5Mn1.5O4/MCMB Li‐Ion Batteries.
- Author
-
Xu, Gaojie, Pang, Chunguang, Chen, Bingbing, Ma, Jun, Wang, Xiao, Chai, Jingchao, Wang, Qingfu, An, Weizhong, Zhou, Xinhong, Cui, Guanglei, and Chen, Liquan
- Subjects
LITHIUM-ion batteries ,PERFORMANCE evaluation ,ADDITIVES ,SULFATES ,ELECTROLYTES ,CHEMICAL decomposition - Abstract
Abstract: In this paper, tris(trimethylsilyl) phosphite (TMSP) and 1,3‐propanediolcyclic sulfate (PCS) are unprecedentedly prescribed as binary functional additives for treating the poor performances of high‐voltage (5 V‐class) LiNi
0.5 Mn1.5 O4 /MCMB (graphitic mesocarbon microbeads) Li‐ion batteries at both room temperature and 50 °C. The high‐voltage LiNi0.5 Mn1.5 O4 /MCMB cell with binary functional additives shows a preponderant discharge capacity retention of 79.5% after 500 cycles at 0.5 C rate at room temperature. By increasing the current intensity from 0.2 to 5 C rate, the discharge capacity retention of the high‐voltage cell with binary functional additives is ≈90%, while the counterpart is only ≈55%. By characterizations, it is rationally demonstrated that the binary functional additives decompose and participate in the modification of solid–electrolyte interface layers (both electrodes), which are more conductive, protective, and resistant to electrolyte oxidative/reductive decompositions (accompanying active‐Li+ consuming parasitic reactions) due to synergistic effects. Specifically, the TMSP additive can stabilize LiPF6 salt and scavenge erosive hydrofluoric acid. More encouragingly, at 50 °C, the high‐voltage cell with binary functional additives holds an ultrahigh discharge capacity retention of 79.5% after 200 cycles at 1 C rate. Moreover, a third designed self‐extinguishing flame‐retardant additive of (ethoxy)‐penta‐fluoro‐cyclo‐triphosphazene (PFPN) is introduced for reducing the flammability of the aforementioned binary functional additives containing electrolyte. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
38. Kinetics and Mechanism of the Thermal and Hydrolytic Decomposition Reaction of Rosocyanin.
- Author
-
John, Jeena, Rugmini, Sudha Devi, and Nair, Balachandran Sreedharan
- Subjects
CURCUMIN ,HYDROLYSIS kinetics ,CHEMICAL decomposition ,ANALYTICAL chemistry ,TEMPERATURE effect ,THERMAL stability - Abstract
ABSTRACT: Spiroborate esters of curcumin find applications in the field of medicinal and analytical chemistry. The present paper reports the hydrolytic and thermal stability of rosocyanin, a 1:2 spiroborate ester of curcumin used for the photometric estimation of boron in different matrices. The effect of temperature, pH, and solvents was monitored spectrophotometrically for the hydrolysis of rosocyanin. The reaction followed first‐order kinetics, and the reaction rate enhanced with an increase in the percentage of water in an aqueous organic mixture, temperature, and pH.
11 B NMR and UV–visible spectra were used to identify the hydrolysis product. The possible mechanistic route for the hydrolysis of rosocyanin was proposed. Solid‐state stability of rosocyanin was investigated by thermogravimetric analysis, and the data were analyzed using different solid‐state reaction models to find the suitable reaction model. Kinetic parameters associated with its thermal decomposition were calculated using Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose isoconversional methods and were compared. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
39. Precision Calcination Mechanism of CaCO3 to High‐Porosity Nanoscale CaO CO2 Sorbent Revealed by Direct In Situ Observations.
- Author
-
Martinez, Jenny, Wardini, Jenna L., Zheng, Xueli, Moghimi, Lauren, Rakowsky, Jason, Means, Jonathan, Guo, Huiming, Kuzmenko, Ivan, Ilavsky, Jan, Zhang, Fan, Dholabhai, Pratik P., Dresselhaus‐Marais, Leora, and Bowman, William J.
- Subjects
CARBON dioxide adsorption ,CARBON sequestration ,TRANSMISSION electron microscopy ,CHEMICAL decomposition ,HETEROGENOUS nucleation ,TEMPERATURE control - Abstract
Deploying energy storage and carbon capture at scale is hindered by the substantial endothermic penalty of decomposing CaCO3 to CaO and CO2, and the rapid loss of CO2 absorption capacity by CaO sorbent particles due to sintering at the high requisite decomposition temperatures. The decomposition reaction mechanism underlying sorbent deactivation remains unclear at the atomic level and nanoscale due to past reliance on postmortem characterization methods with insufficient spatial and temporal resolution. Thus, elucidating the important CaCO3 decomposition reaction pathway requires direct observation by time‐resolved (sub‐)nanoscale methods. Here, chemical and structural dynamics during the decomposition of CaCO3 nanoparticles to nanoporous CaO particles comprising high‐surface‐area CaO nanocrystallites are examined. Comparing in situ transmission electron microscopy (TEM) and synchrotron X‐ray diffraction experiments gives key insights into the dynamics of nanoparticle calcination, involving anisotropic CaCO3 thermal distortion before conversion to thermally dilated energetically stable CaO crystallites. Time‐resolved TEM uncovered a novel CaO formation mechanism involving heterogeneous nucleation at extended CaCO3 defects followed by sweeping reaction front motion across the initial CaCO3 particle. These observations clarify longstanding, yet incomplete, reaction mechanisms and kinetic models lacking accurate information about (sub‐)nanoscale dynamics, while also demonstrating calcination of CaCO3 without sintering through rapid heating and precise temperature control. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Methods for Biochemical Model Decomposition and Quantitative Submodel Comparison.
- Author
-
Mizera, Andrzej, Czeizler, Elena, and Petre, Ion
- Subjects
BIOCHEMISTRY ,CHEMICAL decomposition ,QUANTITATIVE chemical analysis ,CHEMICAL kinetics ,CHEMICAL reactions ,CHEMISTRY periodicals - Abstract
Comparing alternative models for a given biochemical system is in general a very difficult problem: the models may focus on different aspects of the same system and may consist of very different species and reactions. The numerical setups of the models also play a crucial role in the quantitative comparison. When the alternative designs are submodels of a reference model, for example, knockdown mutants of a model, the problem of comparing them becomes simpler: they all have very similar, although not identical, underlying reaction networks, and the biological constraints are given by those in the reference model. In the first part of our study, we review several known methods for model decomposition and for quantitative comparison of submodels. We describe knockdown mutants, elementary flux modes, control-based decomposition, mathematically controlled comparison and its extension, local submodel comparison and a discrete approach for comparing continuous submodels. In the second part of the paper we present a new statistical method for comparing submodels, which complements the methods presented in the review. The main difference between our approach and the known methods is related to the important question of how to chose the numerical setup in which to perform the comparison. In the case of the reviewed methods, the comparison is made in the numerical context of the reference model, i.e., in each of the alternative models both the kinetics of the reactions and the initial values of all variables are chosen to be identical to those from the reference model. We propose in this paper a different approach, better suited for response networks, where each alternative model is assumed to start from its own steady state under basal conditions. We demonstrate our approach with a case study focusing on the heat shock response in eukaryotes. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
41. Dinuclear Au(I), Au(II) and Au(III) Complexes with (CF2)n Chains: Insights into The Role of Aurophilic Interactions in the Au(I) Oxidation.
- Author
-
Portugués, Alejandro, Bautista, Delia, and Gil‐Rubio, Juan
- Subjects
CHEMICAL decomposition ,REDUCTION potential ,HALOGENATION ,DIPHOSPHINE - Abstract
New dinuclear Au(I), Au(II) and Au(III) complexes containing (CF2)n bridging chains were obtained. Metallomacrocycles [Au2{μ‐(CF2)4}{μ‐diphosphine}] show an uncommon figure‐eight structure, the helicity inversion barrier of which is influenced by aurophilic interactions and steric constraints imposed by the diphosphine. Halogenation of LAu(CF2)4AuL (L=PPh3, PMe3, (dppf)1/2, (binap)1/2) gave [Au(II)]2 species, some of which display unprecedented folded structures with Au−Au bonds. Aurophilic interactions facilitate this oxidation process by preorganizing the starting [Au(I)]2 complexes and lowering its redox potential. The obtained [Au(II)]2 complexes undergo thermal or photochemical elimination of R3PAuX to give Au(III) perfluorinated auracycles. Evidence of a radical mechanism for these decomposition reactions was obtained. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
42. Effect of Electron-Transport Material on Light-Induced Degradation of Inverted Planar Junction Perovskite Solar Cells.
- Author
-
Akbulatov, Azat F., Frolova, Lyubov A., Griffin, Monroe P., Gearba, Ioana R., Dolocan, Andrei, Vanden Bout, David A., Tsarev, Sergey, Katz, Eugene A., Shestakov, Alexander F., Stevenson, Keith J., and Troshin, Pavel A.
- Subjects
SOLAR cells ,ELECTRON transport ,CHEMICAL decomposition ,METHYL formate ,MASS spectrometry ,LEAD iodide - Abstract
This paper presents a systematic study of the influence of electron-transport materials on the operation stability of the inverted perovskite solar cells under both laboratory indoor and the natural outdoor conditions in the Negev desert. It is shown that all devices incorporating a Phenyl C
61 Butyric Acid Methyl ester ([60]PCBM) layer undergo rapid degradation under illumination without exposure to oxygen and moisture. Time-of-flight secondary ion mass spectrometry depth profiling reveals that volatile products from the decomposition of methylammonium lead iodide (MAPbI3 ) films diffuse through the [60]PCBM layer, go all the way toward the top metal electrode, and induce its severe corrosion with the formation of an interfacial AgI layer. On the contrary, alternative electron-transport material based on the perylendiimide derivative provides good isolation for the MAPbI3 films preventing their decomposition and resulting in significantly improved device operation stability. The obtained results strongly suggest that the current approach to design inverted perovskite solar cells should evolve with respect to the replacement of the commonly used fullerene-based electron-transport layers with other types of materials (e.g., functionalized perylene diimides). It is believed that these findings pave a way toward substantial improvements in the stability of the perovskite solar cells, which are essential for successful commercialization of this photovoltaic technology. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
43. Synthesis and Characterization of New Calixarenes Containing Explosives with High Temperature Stabilities.
- Author
-
Zhang, Xingcheng, Xiong, Hualin, Yang, Hongwei, and Cheng, Guangbin
- Subjects
CALIXARENES synthesis ,THERMAL stability ,HIGH temperature chemistry ,SUBSTITUTION reactions ,CHEMICAL sample preparation ,CHEMICAL decomposition - Abstract
A few of novel, thermally stable, nitro-substituted calixanes were successfully synthesized and their spatial configurations also were confirmed. 1
4 ,16 ,34 ,36 ,54 ,56 ,74 ,76 -octanitro-2,4,6,8-tetraoxa-1,3,5,7(1,3)-tetraben-zenacyclooctaphane ( 7) as heat-resistant explosives can be prepared by means of a facile synthetic produced and shows outstanding properties (good thermal stability and high thermal decomposition temperature and energetic performances). It has also been pointed out that the production of compound 7 is very easy on a large scale. All target compounds was characterized by single-crystal X-ray diffraction, NMR and elemental analysis, TG and DSC. In this paper, the macrocyclic compounds are introduced into the study as heat-resistant explosives firstly, which will change the past stagnant situation! [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
44. A complete decomposition and coordination algorithm for large-scale hydrothermal optimal power flow problems.
- Author
-
Wang, Chaoqun, Wei, Hua, and Tan, Jiancheng
- Subjects
HYDROTHERMAL alteration ,OCEAN thermal power plants ,ALGORITHMS ,CHEMICAL decomposition ,TECHNOLOGY convergence - Abstract
This paper presents a complete decomposition and coordination algorithm to solve large-scale hydrothermal optimal power flow (HTOPF) problems. Based on the approximate Newton directions method, which decouples the first-order Karush-Kuhn-Tucker conditions of the original problem, an HTOPF problem with cascaded hydro plants is decomposed into a thermal plant subproblem with independent optimal power flow solutions for each time period and a hydro plant subproblem combined with fixed and variable heads and cascaded plants issues. In order to verify the effectiveness of the proposed algorithm, numerical tests are performed on three large-scale test systems with up to 3120 buses and 7 531 915 primal-dual variables over 168 time periods. Test results show that the proposed algorithm gives excellent performances in convergence and stability. It not only reduces memory usage significantly but also decreases CPU time by about 65-75%. With parallel computing, it is capable of achieving 10-20 times or even 1000 times speed without loss of optimality. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
45. Effect of Communication Quality Degradation on Web Usability over 6to4 Networks.
- Author
-
MIZOGUCHI, TOMOHIKO, ITO, YOSHIHIRO, and KOYASHIKI, RYO
- Subjects
QUANTUM tunneling ,WEB services ,INTERNET ,CHEMICAL decomposition ,COMMUNICATION - Abstract
SUMMARY This paper evaluates effect on the overheads caused by 6to4 tunneling on QoE for Web services by experiment. The authors consider Web usability as QoE and treat three actual Web services which support both of the IPv4 Internet and the IPv6 Internet. The results show that the effect of QoS degradation caused by 6to4 on Web usability depends on the Web service. According to Web service, QoE degradation caused by 6to4 does not always occur. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
46. Modeling the depletion of dissolved oxygen in a water body located near a city.
- Author
-
Venturino, Ezio, Tiwari, P.K., and Misra, A.K.
- Subjects
DISSOLVED oxygen in water ,MATHEMATICAL models of population ,WATER purification ,COMPUTER simulation ,CHEMICAL decomposition - Abstract
Water bodies located nearby cities are much prone to pollution, especially in the developing countries, where effluents treatment facilities are generally lacking. The main reason for this phenomenon is the increasing population in the cities, and the large number of industries located near them. This leads to generation of huge amounts of domestic and industrial sewage that is discharged into the water bodies, increasing their organic pollutant load and resulting in the depletion of dissolved oxygen. In this paper, we propose a mathematical model for this situation, focusing especially on the resulting quality of the water, determined by the level of dissolved oxygen. The model also accounts for resources needed for the population survival and for the industrial operations. In addition, we describe also the decomposition of organic pollutants by bacteria in the aquatic medium. Feasibility conditions and stability criteria of the system's equilibria are determined analytically. The results show that human population and industries are relevant influential factors responsible for the increase in organic pollutants and the decrease in dissolved oxygen in the water body, in the sense that they may exert a destabilizing effect on the system. The numerical simulations confirm the analytical results. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
47. Ascorbate degradation in tomato leads to accumulation of oxalate, threonate and oxalyl threonate.
- Author
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Truffault, Vincent, Fry, Stephen C., Stevens, Rebecca G., and Gautier, Hélène
- Subjects
- *
VITAMIN content of food , *CARBOHYDRATES , *ASCORBATE oxidase , *OXALATES , *CHEMICAL decomposition - Abstract
Ascorbate content in plants is controlled by its synthesis from carbohydrates, recycling of the oxidized forms and degradation. Of these pathways, ascorbate degradation is the least studied and represents a lack of knowledge that could impair improvement of ascorbate content in fruits and vegetables as degradation is non-reversible and leads to a depletion of the ascorbate pool. The present study revealed the nature of degradation products using [14C]ascorbate labelling in tomato, a model plant for fleshy fruits; oxalate and threonate are accumulated in leaves, as is oxalyl threonate. Carboxypentonates coming from diketogulonate degradation were detected in relatively insoluble (cell wall-rich) leaf material. No [14C]tartaric acid was found in tomato leaves. Ascorbate degradation was stimulated by darkness, and the degradation rate was evaluated at 63% of the ascorbate pool per day, a percentage that was constant and independent of the initial ascorbate or dehydroascorbic acid concentration over periods of 24 h or more. Furthermore, degradation could be partially affected by the ascorbate recycling pathway, as lines under-expressing monodehydroascorbate reductase showed a slight decrease in degradation product accumulation. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
48. A Systems-Level Roadmap for Biomass Thermal Fractionation and Catalytic Upgrading Strategies.
- Author
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Herron, Jeffrey A., Vann, Tyler, Duong, Nhung, Resasco, Daniel E., Crossley, Steven, Lobban, Lance L., and Maravelias, Christos T.
- Subjects
BIOMASS ,CHEMICAL decomposition ,CATALYTIC reforming - Abstract
Although multistage thermal decomposition (fractionation) of biomass with catalytic upgrading is a promising strategy of achieving sustainable fuels production, the number of thermal decomposition stages, their conditions, and the optimal catalytic upgrading chemistries are not known. In this paper, we use conceptual process modeling to propose a general roadmap for the design of a biorefinery by employing these technologies. The overall process considered includes a biomass pretreatment system, a (multistage) thermal decomposition system in which the biomass in decomposed into various fractions, a fraction upgrading system, and a combustion system. We focus primarily on the design of the thermal decomposition and fraction upgrading systems. The goal of our work is to demonstrate the key trade-offs between various process options and to identify important areas for improvement. In general, increasing the complexity of the fraction upgrading systems increases the ultimate yield of C
6+ products, though there are diminishing returns on the increase in product yield versus the complexity of the catalytic upgrading sequences. The choice of the number of thermal decomposition stages is not simple and requires careful consideration of the chemistries available to upgrade different components and the relative abundances of these different components. Therefore, the optimal design of the thermal decomposition and fraction upgrading systems cannot be done independently. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
49. Tensor decompositions and data fusion in epileptic electroencephalography and functional magnetic resonance imaging data.
- Author
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Hunyadi, Borbála, Dupont, Patrick, Van Paesschen, Wim, and Van Huffel, Sabine
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ELECTROENCEPHALOGRAPHY ,FUNCTIONAL magnetic resonance imaging ,BLIND source separation ,CHEMICAL decomposition ,BIODEGRADATION - Abstract
Electroencephalography ( EEG) and functional magnetic resonance imaging ( fMRI) record a mixture of ongoing neural processes, physiological and nonphysiological noise. The pattern of interest, such as epileptic activity, is often hidden within this noisy mixture. Therefore, blind source separation ( BSS) techniques, which can retrieve the activity pattern of each underlying source, are very useful. Tensor decomposition techniques are very well suited to solve the BSS problem, as they provide a unique solution under mild constraints. Uniqueness is crucial for an unambiguous interpretation of the components, matching them to true neural processes and characterizing them using the component signatures. Moreover, tensors provide a natural representation of the inherently multidimensional EEG and fMRI, and preserve the structural information defined by the interdependencies among the various modes such as channels, time, patients, etc. Despite the well-developed theoretical framework, tensor-based analysis of real, large-scale clinical datasets is still scarce. Indeed, the application of tensor methods is not straightforward. Finding an appropriate tensor representation, suitable tensor model, and interpretation are application dependent choices, which require expertise both in neuroscience and in multilinear algebra. The aim of this paper is to provide a general guideline for these choices and illustrate them through successful applications in epilepsy. WIREs Data Mining Knowl Discov 2017, 7:e1197. doi: 10.1002/widm.1197 For further resources related to this article, please visit the . [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
50. Multisurface plasticity for Cosserat materials: Plate element implementation and validation.
- Author
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Godio, Michele, Stefanou, Ioannis, Sab, Karam, and Sulem, Jean
- Subjects
MATERIAL plasticity ,MICROPOLAR elasticity ,TIME-dependent density functional theory ,FINITE element method ,CHEMICAL decomposition - Abstract
The macroscopic behavior of materials is affected by their inner micro-structure. Elementary considerations based on the arrangement, and the physical and mechanical features of the micro-structure may lead to the formulation of elastoplastic constitutive laws, involving hardening/softening mechanisms and non-associative properties. In order to model the non-linear behavior of micro-structured materials, the classical theory of time-independent multisurface plasticity is herein extended to Cosserat continua. The account for plastic relative strains and curvatures is made by means of a robust quadratic-convergent projection algorithm, specifically formulated for non-associative and hardening/softening plasticity. Some important limitations of the classical implementation of the algorithm for multisurface plasticity prevent its application for any plastic surfaces and loading conditions. These limitations are addressed in this paper, and a robust solution strategy based on the singular value decomposition technique is proposed. The projection algorithm is then implemented into a finite element formulation for Cosserat continua. A specific finite element is considered, developed for micropolar plates. The element is validated through illustrative examples and applications, showing able performance. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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