9,460 results on '"STABILITY"'
Search Results
2. The Stability of Cylindrical Pendant Drops
- Author
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John McCuan and John McCuan
- Subjects
- Drops, Spheroidal state, Fluid mechanics, Stability, Liquids
- Abstract
The author considers the stability of certain liquid drops in a gravity field satisfying a mixed boundary condition. He also considers as special cases portions of cylinders that model either the zero gravity case or soap films with the same kind of boundary behavior.
- Published
- 2018
3. Generalized TASE-RK methods for stiff problems
- Author
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S. González-Pinto, D. Hernández-Abreu, G. Pagano, and S. Pérez-Rodríguez
- Subjects
Computational Mathematics ,Numerical Analysis ,Explicit Runge-Kutta methods ,TASE-RK methods ,W-methods ,Rosenbrock methods ,Time integration ,Stability ,Stiffness ,Applied Mathematics - Published
- 2023
4. Application of correlation coefficients and principal components analysis in stability of quantitative and qualitative traits on rice improvement cultivation
- Author
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M. Nikzad Semeskandi, P. Mazloom, B. Arabzadeh, M. N. Moghadam, and T. Ahmadi
- Subjects
PCA ,rice ,irrigation regimes ,correlation ,adaptability ,regimes de irrigação ,arroz ,adaptabilidade ,stability ,estabilidade ,correlação ,General Agricultural and Biological Sciences - Abstract
In order to investigate the stability of qualitative and quantitative traits and choose the most appropriate cultivation method and irrigation regime in rice plants, the experiment was conducted in the form of a split-plot design based on a randomized complete block design in three replications and in two cropping years. The results of compound analysis indicated that the effect of year × irrigation regimes in terms of traits, grain yield, rainfall, productivity 2, number of full grains, number of hollow grains, harvest index, percentage of crushed grains and yield of white rice, the effect of year × Cultivation method characteristics in terms of water consumption, rainfall, productivity 1, number of tillers, plant height, spike length, number of hollow grains, thousand seed weight, small grain percentage and white rice yield and the effect of irrigation regime × cultivation methods in terms of all Traits except traits productivity 2 were significant. The results of the mean comparison of the interaction effect of irrigation regimes and cultivation methods also showed that treatments T1W1, T2W1 and T1W3 are favorable for all evaluated traits. Based on the table of correlation coefficients, correlation diagram and map of the intensity of the correlation in the years of the experiment, it is possible to report the correlation of the grain yield trait with the traits of water consumption, rainfall, plant height, 100- seed weight, full grain number and white rice yield. Also, traits productivity 1, productivity 2 and small grain percentage showed a positive correlation and a negative correlation of these three traits with most of the traits evaluated in the experiment was observed. Based on the analysis of the main components, the first four main components explained the most data variance, and T2W2 and T2W3 treatments were identified as suitable treatments for rice cultivation in terms of the first and second main components. Resumo Para investigar a estabilidade dos caracteres qualitativos e quantitativos e escolher o método de cultivo e regime de irrigação mais adequados em plantas de arroz, o experimento foi conduzido em esquema de parcelas subdivididas em blocos completos em três repetições e em dois anos de colheita. Os resultados da análise composta indicaram os seguintes fatores significativos: o efeito dos regimes de irrigação do ano X em termos de características, rendimento de grãos, pluviosidade, produtividade 2, número de grãos cheios, número de grãos ocos, índice de colheita, porcentagem de grãos esmagados e rendimento de arroz branco, o efeito do ano X, características do método de cultivo relativamente ao consumo de água, precipitação, produtividade 1, número de perfilhos, altura da planta, comprimento da espiga, número de grãos ocos, peso de 1000 sementes, porcentagem de grãos pequenos e rendimento de arroz branco e o efeito da irrigação no regime X, métodos de cultivo em relação a todos os caracteres, exceto os caracteres produtividade 2. Já os resultados da comparação média do efeito de interação entre regimes de irrigação e métodos de cultivo também mostraram que os tratamentos T1W1, T2W1 e T1W3 são favoráveis para todas as características avaliadas. Com base na tabela de coeficientes de correlação, diagrama de correlação e mapa da intensidade da correlação nos anos do experimento, é possível relatar a correlação da característica produtividade de grãos com as características consumo de água, pluviosidade, altura de planta, 100 - peso da semente, número de grãos cheios e rendimento do arroz branco. Além disso, os caracteres produtividade 1, produtividade 2 e porcentagem de grãos pequenos apresentaram correlação positiva e foi observada correlação negativa desses 3 caracteres com a maioria dos caracteres avaliados no experimento. Por fim, com base na análise dos componentes principais, os quatro primeiros componentes principais explicaram a maior variância dos dados, e os tratamentos T2W2 e T2W3 foram identificados como tratamentos adequados para o cultivo de arroz quanto aos primeiro e segundo componentes principais.
- Published
- 2024
5. Aumento no desempenho de rendimento de genótipos de soja induzidos por mutação em condições agroecológicas variadas
- Author
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M. S. H. Bhuiyan, M. A. Malek, R. M. Emon, M. K. Khatun, Mohammad Moneruzzaman Khandaker, and Md. Amirul Alam
- Subjects
herdabilidade ,Genotype ,QH301-705.5 ,Science ,soybean mutant ,heritability ,melhoramento genético por mutação ,variância genética ,estabilidade ,Biology (General) ,Bangladesh ,yield performance ,soja mutante ,desempenho produtivo ,fungi ,Botany ,food and beverages ,mutation breeding ,stability ,Plant Breeding ,Phenotype ,QL1-991 ,QK1-989 ,Mutation ,Soybeans ,genetic variance ,Zoology - Abstract
In soybean breeding program, continuous selection pressure on traits response to yield created a genetic bottleneck for improvements of soybean through hybridization breeding technique. Therefore an initiative was taken to developed high yielding soybean variety applying mutation breeding techniques at Plant Breeding Division, Bangladesh Institute of Nuclear Agriculture (BINA), Bangladesh. Locally available popular cultivar BARI Soybean-5 was used as a parent material and subjected to five different doses of Gamma ray using Co60. In respect to seed yield and yield attributing characters, twelve true breed mutants were selected from M4 generation. High values of heritability and genetic advance with high genotypic coefficient of variance (GCV) for plant height, branch number and pod number were considered as favorable attributes for soybean improvement that ensure expected yield. The mutant SBM-18 obtained from 250Gy provided stable yield performance at diversified environments. It provided maximum seed yield of 3056 kg ha-1 with highest number of pods plant-1 (56). The National Seed Board of Bangladesh (NSB) eventually approved SBM-18 and registered it as a new soybean variety named ‘Binasoybean-5’ for large-scale planting because of its superior stability in various agro-ecological zones and consistent yield performance. Resumo No programa de melhoramento da soja, a pressão pela seleção contínua para a resposta das características de rendimento criou um gargalo genético para melhorias da soja por meio da técnica de melhoramento por hibridação. Portanto, foi desenvolvida uma variedade de soja de alto rendimento, aplicando técnicas de reprodução por mutação, na Divisão de Melhoramento de Plantas, no Instituto de Agricultura Nuclear de Bangladesh (BINA), em Bangladesh. A cultivar popular BARI Soybean-5, disponível localmente, foi usada como material original e submetida a cinco doses diferentes de raios gama usando Co60. Em relação ao rendimento de sementes e às características de atribuição de rendimento, 12 mutantes genuínos foram selecionados a partir da geração M4. Altos valores de herdabilidade e avanço genético com alto coeficiente de variância genotípico (GCV) para altura da planta, número de ramos e número de vagens foram considerados atributos favoráveis ao melhoramento da soja, garantindo, assim, a produtividade esperada. O mutante SBM-18, obtido a partir de 250Gy, proporcionou desempenho de rendimento estável em ambientes diversificados e produtividade máxima de sementes de 3.056 kg ha-1 com o maior número de vagens planta-1 (56). O Conselho Nacional de Sementes de Bangladesh (NSB) finalmente aprovou o SBM-18 e o registrou como uma nova variedade de soja, chamada ‘Binasoybean-5’, para plantio em larga escala por causa de sua estabilidade superior em várias zonas agroecológicas e desempenho de rendimento consistente.
- Published
- 2024
6. Lead immobilization for environmentally sustainable perovskite solar cells
- Author
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Hui Zhang, Jin-Wook Lee, Giuseppe Nasti, Richard Handy, Antonio Abate, Michael Grätzel, and Nam-Gyu Park
- Subjects
life-cycle assessment ,Multidisciplinary ,metal ,hybrid ,exposure ,toxicity ,pollution ,stability ,health-hazards ,efficient - Abstract
Lead halide perovskites are promising semiconducting materials for solar energy harvesting. However, the presence of heavy-metal lead ions is problematic when considering potential harmful leakage into the environment from broken cells and also from a public acceptance point of view. Moreover, strict legislation on the use of lead around the world has driven innovation in the development of strategies for recycling end-of-life products by means of environmentally friendly and cost-effective routes. Lead immobilization is a strategy to transform water-soluble lead ions into insoluble, nonbioavailable and nontransportable forms over large pH and temperature ranges and to suppress lead leakage if the devices are damaged. An ideal methodology should ensure sufficient lead-chelating capability without substantially influencing the device performance, production cost and recycling. Here we analyse chemical approaches to immobilize Pb2+ from perovskite solar cells, such as grain isolation, lead complexation, structure integration and adsorption of leaked lead, based on their feasibility to suppress lead leakage to a minimal level. We highlight the need for a standard lead-leakage test and related mathematical model to be established for the reliable evaluation of the potential environmental risk of perovskite optoelectronics.
- Published
- 2023
7. Evaluation of the effectiveness of secondary support of haulage drifts based on a comparative analysis of the deformation characteristics of protective structures
- Author
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Oleksandr Tkachuk, Daria Chepiga, Serhii Pakhomov, Serhiy Volkov, Yaroslav Liashok, Yaroslava Bachurina, Iryna Shvets, and Serhii Podkopaiev
- Subjects
deformation characteristics ,Applied Mathematics ,Mechanical Engineering ,protective structures ,coal rock array ,Energy Engineering and Power Technology ,stability ,compression ,Industrial and Manufacturing Engineering ,potential energy ,Computer Science Applications ,Control and Systems Engineering ,Management of Technology and Innovation ,Environmental Chemistry ,compaction ,Electrical and Electronic Engineering ,Food Science - Abstract
The object of this study is the processes of managing the state of lateral rocks in the coal rock array with preparatory workings. The influence of deformation characteristics of the protective structures of the preparatory workings on the stability of lateral rocks in the coal rock array has been established. The stable state of the above-the-drift pillars of coal is provided within the deformation resource, which corresponds to the critical level of the specific potential energy of the deformation. The limits of the deformation resource are the range of change in the relative deformation of coal pillars 0.1≤λ≤0.25. When the critical level of the specific potential energy of deformation is passed, at λ˃0.25, there is a relative change in the volume of pillars δλ˃0,1, as a result of which their durability decreases and the state changes. Under such conditions, the residual strength of coal pillars is not enough to limit the movement of lateral rocks, which provokes their collapse. For protective structures made of crushed rock, within the established deformation resource of 0.4≤λ≤0.7, with an increase in static load and cross-sectional area, the specific potential energy of deformation decreases, simultaneously with the relative change in the volume of the embedded material. This is due to the compaction of the crushed rock and an increase in its strength. Regularities of change in the specific potential energy of deformation of protective structures have been established, which, under conditions of uniaxial compression, make it possible to assess, within the deformation resource, their stability. To ensure the stability of lateral rocks in the coal rock array and to preserve the operational condition of the preparatory workings, it is advisable to use protective structures made of crushed rock. This method will limit the movement of the roof and sole in the produced space and avoid collapses.
- Published
- 2023
8. The Effects of Surfactant and Metal Ions on the Stability and Rheological Properties of Nanoemulsions Loaded with Gardenia Yellow Pigment
- Author
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Li Gao and Bin Li
- Subjects
Geography, Planning and Development ,gardenia yellow pigment ,nanoemulsion ,hydrophilic–lipophilic balance ,stability ,rheology - Abstract
The present work reports the preparation of gardenia yellow pigment containing paraffin oil nanoemulsions stabilized by Span80 and Tween80. The preparation of the required nanoemulsions was optimized by testing different conditions, such as varying the hydrophilic–lipophilic balance (HLB), the emulsifier concentration (EC), the oil–water ratio (OWR), and the temperature (T), as determined by the average droplet diameter (ADD) and polydispersity index (PDI). Our results indicated that a minimum ADD of 65.9 nm and PDI of 0.116 were obtained at an optimum HLB value of 6.0, EC of 10% (w/w), OWR of 2:1, and T of 40 °C. Both the steady-state and dynamic rheological parameters were further investigated, revealing that the emulsions exhibited pseudoplastic behaviors. The long-term stabilities of the nanoemulsions after the addition of inorganic salts were monitored by observing their visual appearances. It was found that the emulsions containing pure water or 0.1 M CaCl2 and AlCl3 became slightly separated, while the emulsions containing 0.1 M KCl and NaCl showed no separation after 30 days of storage at room T. This difference among different salts could be related to the number of valence electrons of their cations. The spatial electrostatic effects of the monovalent cationic (KCl and NaCl) and the nonionic surfactants were greater than the delamination/sedimentation forces of the system, which was better than the salt based on the cations with valences greater than one (CaCl2 and AlCl3). In conclusion, the present work illustrated the formation, rheological properties, and stability of water containing gardenia yellow pigment in paraffin oil nanoemulsions, which can be of great significance for the application of gardenia-yellow-pigment-based formulations.
- Published
- 2023
9. The critical role of the donor polymer in the stability of high-performance non-fullerene acceptor organic solar cells
- Author
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Yiwen Wang, Joel Luke, Alberto Privitera, Nicolas Rolland, Chiara Labanti, Giacomo Londi, Vincent Lemaur, Daniel T.W. Toolan, Alexander J. Sneyd, Soyeong Jeong, Deping Qian, Yoann Olivier, Lorenzo Sorace, Ji-Seon Kim, David Beljonne, Zhe Li, and Alexander J. Gillett
- Subjects
material degradation ,General Energy ,transient absorption spectroscopy ,Raman spectroscopy ,electron paramagnetic resonance spectroscopy ,organic solar cell ,non-fullerene electron acceptor ,stability ,polaron pairs - Abstract
The poor operational stability of non-fullerene electron acceptor (NFA) organic solar cells (OSCs) currently limits their commercial application. While previous studies have primarily focused on the degradation of the NFA component, we also consider here the electron donor material. We examine the stability of three representative donor polymers, PM6, D18, and PTQ10, paired with the benchmark NFA, Y6. After light soaking PM6 and D18 in air, we find an enhanced conversion of singlet excitons into trapped interchain polaron pairs on sub-100 femtosecond timescales. This process outcompetes electron transfer to Y6, significantly reducing the charge generation yield. However, this pathway is absent in PTQ10. We identify twisting in the benzo[1,2-b:4,5-b′]dithiophene (BDT)-thiophene motif shared by PM6 and D18 as the cause. By contrast, PTQ10 does not contain this structural motif and has improved stability. Thus, we show that the donor polymer can be a weak link for OSC stability, which must be addressed collectively with the NFA.
- Published
- 2023
10. Stability analysis of ef Gaussian direct quadrature methods for Volterra integral equations
- Author
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Angelamaria Cardone
- Subjects
Computational Mathematics ,Numerical Analysis ,Exponential fitting ,Volterra integral equations ,Applied Mathematics ,Direct Quadrature ,Stability - Published
- 2023
11. Low-Frequency Passivity-Based Analysis and Damping of Power-Synchronization Controlled Grid-Forming Inverter
- Author
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Fangzhou Zhao, Xiongfei Wang, and Tianhua Zhu
- Subjects
Eigenvalues and eigenfunctions ,Grid-forming inverter ,passivity index ,Frequency control ,Resistance ,Energy Engineering and Power Technology ,Indexes ,Admittance ,Inverters ,Synchronization ,stability ,Electrical and Electronic Engineering ,virtual reactance - Abstract
This paper presents a passivity-based analysis and damping method for the low-frequency dynamics of grid-forming (GFM) control. A closed-form analytical solution to the positive realness of control input admittance is developed, which reveals the inherent non-passive property of GFM control. This feature gives rise to the risk of instability, especially in connection with a nearby non-passive GFM inverter, which may induce undesired control interactions. It is further revealed that the passivity index is determined by a low-frequency resonance around 10 Hz in the dq-frame, and this resonance can be better dampened, therefore with enhanced passivity index, by using a virtual reactance than using a virtual resistance. Finally, the theoretical findings are verified by the experimental results.
- Published
- 2023
12. Stability of Rosenzweig–MacArthur models with non-diffusive dispersal on non-regular networks
- Author
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Ryusuke Kon and Dinesh Kumar
- Subjects
Network structure ,Geometric singular perturbation theory ,Rosenzweig–MacArthur model ,Stability ,Ecology, Evolution, Behavior and Systematics - Abstract
This paper examines the stability of the Rosenzweig–MacArthur model distributed to identical discrete habitat patches. Migration between patches is assumed to follow the non-diffusive rule that individuals have a fixed rate of leaving their local habitat patch and migrating to another. Under this non-diffusive migration rule, we found that population dispersal on a non-regular and connected habitat network can both stabilize and destabilize the Rosenzweig–MacArthur model. It is also shown that our non-diffusive migration rule apparently becomes diffusive if the habitat network is regular.
- Published
- 2023
13. Heat Stress Response of Bread Wheat Genotypes Under High and Low Rainfall Environments
- Author
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Mehmet KARAMAN, Cuma AKINCI, Mehmet YILDIRIM, Dicle Üniversitesi, Ziraat Fakültesi, Tarla Bitkileri Bölümü, Akıncı, Cuma, and Yıldırım, Mehmet
- Subjects
Heat and drought stress ,GGE biplot ,Grain yield ,Bread wheat ,General Agricultural and Biological Sciences ,Stability - Abstract
The research was carried out to determine the yield, yield components, quality, and stability of the bread wheat (Triticum aestivum L.) genotypes in heat-stressed and water-limited environments for two years. ANOVA and GGE biplot analysis were applied to determine the differences and relationships of investigated traits belonging to 10 different wheat varieties. While grain yield (GY) is associated with thousand-grain weight (TGW) and test weight (TW); protein ratio (PR) was found to be positively correlated with heading time (HT) and the number of spikes per square meter (SN). Besides, spike weight (SW) was found to be negatively correlated with PR, HT, and (SN). The biplot graph showed that PC1 explained 83.67% of the variability and the proportion attributed to PC2 was 16.33%. The cultivar of Kate A-1 was the most stable genotype, according to the biplot graph and it could be visually determined from the biplot graph in PC1 and PC2 together to explain 100% of the variability. In terms of the quality characteristics examined, Tahirova 2000 passed other varieties. It was concluded that Kate A-1 and Anapo varieties can be used for grain yield-oriented breeding studies, while Tahirova 2000 and Karatopak varieties can be used as parents for quality purposes.
- Published
- 2023
14. Electrocatalytic Reduction of O2 by ITO-IrOx: Implication for Dissolved Oxygen Sensor in the Alkaline Medium
- Author
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Munira Siddika, Md. Mahmudul Hasan, Tahamida A. Oyshi, and Mohammad A. Hasnat
- Subjects
Iridium oxide ,oxygen reduction reaction ,dissolved oxygen ,sensitivity ,stability ,General Medicine - Abstract
Water pollution has badly affected human health, aquatic life, and the ecosystem. The purity of surface water can be measured in terms of dissolved oxygen (DO) measurements. Hence, it is desirable to have a portable and simple-to-use dissolved oxygen sensor. One possible remedy is an electrochemical sensor. Thus, we proposed an ITO-IrOx electrocatalyst for an effective and interference-free DO sensor utilizing the principle of oxygen reduction reaction (ORR). The ITO-IrOx was characterized using cyclic voltammetry (CV), scanning electron microscopy (SEM), electrochemical impedance spectrometry (EIS), X-ray photoelectron spectroscopy (XPS), and reflectance spectroscopy-based techniques. Reflectance spectra of the ITO-IrOx electrode showed the photoresist capability. The EIS spectra revealed lower charge transfer resistance for the ITO-IrOx electrode in ORR. The IrOx film on ITO exhibited a quick (one electron, α = 1.00), and reversible electron transfer mechanism. The electrode demonstrated high stability for oxygen sensing, having a limit of detection (LOD) of 0.49 ppm and interference-free from some common ions (nitrate, sulphate, chloride etc.) found in water.
- Published
- 2023
15. Quasi-interpolation in Spline Spaces: Local Stability and Approximation Properties
- Author
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CASTILLO, M. E. and GARAU, E. M.
- Subjects
B-splines ,quasi-interpolation ,General Medicine ,stability ,spline approximation - Abstract
In this work we analyze the approximation error in Sobolev norms for quasi-interpolation operators in spline spaces. We establish in a general way the hypotheses on a quasi-interpolant to achieve the optimal order of approximation. Finally, we propose simple but general constructions of such operators that satisfy the established hypotheses and illustrate their performance through some numerical tests.
- Published
- 2023
16. Architecture-Controllable Single-Crystal Helical Self-assembly of Small-Molecule Disulfides with Dynamic Chirality
- Author
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Qi Zhang, Ryojun Toyoda, Lukas Pfeifer, Ben L. Feringa, and Synthetic Organic Chemistry
- Subjects
Colloid and Surface Chemistry ,General Chemistry ,amplification ,stability ,Biochemistry ,polymers ,Catalysis - Abstract
Beyond the common supramolecular helical polymers in solutions, controlling single-crystal helical self-assembly with precisely defined chirality and architectures has been challenging. Here, we report that simply merging static homochiral amino acids with dynamic chiral disulfides can produce a class of building blocks featuring supramolecular helical single-crystal self-assembly with unusual stereodivergency. Analysis of 20 single-crystal structures of 1,2-dithiolanes gives an atom-precision understanding of the chirality transfer from the molecular to supramolecular level, featuring homochiral and heterochiral helical supramolecular self-assembly in the solid state. The underlying structure-assembly relationship reveals that the synergistic interplay of intermolecular H-bonds and the 1,2-dithiolane ring with adaptive chirality plays a key role in determining the assembly pathway, also involving the effects of residue groups, substituents, molecular stacking, and solvents. The confinement effect in the solid state can stabilize the dynamic stereochemistry of disulfide bonds and selectively result in specific conformers that can minimize the energy of global supramolecular systems. We envision that these results represent a starting point to use dynamic chiral disulfide as a functional entity in supramolecular chemistry and may inspire a new class of supramolecular helical polymers with dynamic functions.
- Published
- 2023
17. A long term analysis of stochastic theta methods for mean reverting linear process with jumps
- Author
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Raffaele D'Ambrosio, Afsaneh Moradi, and Carmela Scalone
- Subjects
Computational Mathematics ,Numerical Analysis ,Long term behavior ,Applied Mathematics ,Poisson jump ,Stability ,Stochastic theta methods - Published
- 2023
18. 1+ XTZ States within QCD Sum Rules
- Author
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Albuquerque, R. M., Narison, S., Rabetiarivony, D., and HEP, INSPIRE
- Subjects
quark model ,Nuclear and High Energy Physics ,Laplace ,axial-vector ,FOS: Physical sciences ,tetraquark ,stability ,sum rule ,[PHYS.HPHE] Physics [physics]/High Energy Physics - Phenomenology [hep-ph] ,High Energy Physics - Phenomenology ,High Energy Physics - Phenomenology (hep-ph) ,quantum chromodynamics ,mass ratio ,lattice - Abstract
We present improved estimates of the couplings, masses and mass ratios of the $X_Q, Z_Q$ and $T_{QQ\bar q\bar q'}$ states using (inverse) QCD Laplace sum rules (LSR), their ratios ${\cal R}$ and double ratios (DRSR), within stability criteria. We conclude that the observed $X_c(3872)$ and $Z_c(3900)$ are tetramoles states (superposition of quasi-degenerated molecule and tetraquark states having similar couplings to the currents) with the predicted masses: $M_{{\cal T}_{X_c}}=3876(44)$ MeV and $M_{{\cal T}_{Z_c}}=3900(42)$ MeV. We also do an extensive analysis of the four-quark nature of different $T_{QQ\bar q\bar q'}$ axial-vector states. Then, combining ${\cal R}$ and DRSR, we reanalyze the observed state $X_c(3872)$ and we obtain a precise prediction of $M_{T_{cc}^{1^+}}$=3886(6) MeV. Extending to the beauty sector, we find the results: $M_{{\cal T}_{Z_b}}=10579(99)$ MeV and $M_{X_b}=10545(131)$ MeV. Finally, we confront our combined LSR $\oplus$ DRSR results with the ones from some other approaches (lattices and quark models)., Comment: To appear in the proceedings of the 25th High-Energy Physics International Conference in Quantum Chromodynamics (QCD 22)
- Published
- 2023
19. Optimized fuzzy PI controller for variable speed wind turbine using DE algorithm
- Author
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Khaddouj Ben Meziane, Faiza Dib, Nabil Benaya, and Ismail Boumhidi
- Subjects
Fuzzy logic ,Wind turbine system ,PI controller ,DE algorithm ,Stability ,Wind energy - Abstract
To design an optimal fuzzy proportional-integral (PI) controller for the variable speed wind turbine systems, a new differential evolution (DE) algorithm approach is developed in this paper. We have investigated a fuzzy PI controller, in which fuzzy rules are applied to adapt the parameters of the PI controller founded on the error and its first-time derivative. The fuzzy PI controller's inputs and outputs are tuned using the DE optimization method. The superiority of the suggested (DE fuzzy PI) controller has been proved by comparing the results with (fuzzy PI) and only the PI controller applied to the wind turbine system. In comparison to a fuzzy controller with parameters selected by a human operator, the numerical validation results of the suggested approach (DE fuzzy PI) have shown good performance in terms of robustness, pursuit, and response time.
- Published
- 2023
20. ТЕОРЕТИЧНІ ТА ПРАКТИЧНІ АСПЕКТИ УПРАВЛІННЯ ФІНАНСОВОЮ СТІЙКІСТЮ ПІДПРИЄМСТВА
- Author
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Svitlana Osypova and Valery Korzun
- Subjects
фінансова стійкість ,управління ,устойчивость ,General Medicine ,stability ,управління фінансовою стійкістю ,управление ,финансовая устойчивость ,mechanism of enterprise management ,management of financial stability ,управление финансовой устойчивостью ,стійкість ,management ,механизм управления предприятием ,механізм правління підприємством ,financial stability - Abstract
The article considers the basic scientific approaches to the economic contents of the notions of financial stability, mechanism of enterprise management. Offered interpretations of the concept of the mechanism of financial stability enterprise management and main stages of the process of its formation. The activity of the Ukrainian enterprise "Stalkonstruktsia" LLC is characterized. It was determined that during 2019-2021, the company's balance sheet is completely liquid, which indicates a sufficient amount of funds to repay current liabilities. The indicators of the business activity of "Stalkonstruktsia" LLC in 2019-2021 positively characterize the company's activity, namely, the company uses its own capital effectively, we observe an increase in the turnover rate of stocks, finished products, accounts payable and an increase in the efficiency of their use, which is positively reflected in the business activity of the company. It was concluded that the enterprise needs to use more long-term debt financing in its economic activities, which will increase the return on equity., В статье рассмотрены основные научные подходы к определению сущности понятий финансовая устойчивость и механизм управления предприятием, предложена трактовка понятия механизм управления финансовой устойчивостью предприятия и определены основные этапы процесса его формирования. Охарактеризованы деятельность украинского предприятия ООО «Стальконструкция». Определено, что в течение 2019-2021 гг. баланс предприятия абсолютно ликвиден, что свидетельствует о достаточном количестве средств для погашения текущих обязательств. Показатели деловой активности ООО «Стальконструкция» в 2019-2021 годах положительно характеризуют деятельность предприятия, а именно собственный капитал используется предприятием эффективно, наблюдается увеличение скорости оборачиваемости запасов, готовой продукции, кредиторской задолженности и рост эффективности их использования, что отражается на деловой активности предприятия. Сделаны выводы, что предприятию необходимо использовать в своей хозяйственной деятельности больше заемных средств долгосрочного финансирования, что повысит рентабельность собственного капитала., У статті розглянуто основні наукові підходи щодо визначення сутності понять фінансова стійкість і механізм управління підприємством, запропоновано трактування поняття механізм управління фінансовою стійкістю підприємства та визначено основні етапи процесу його формування. Охарактеризовано діяльність українського підприємства ТОВ «Стальконструкція». Визначено, що протягом 2019-2021 рр. баланс підприємства є абсолютно ліквідним, що свідчить про достатню кількість коштів для погашення поточних зобов’язань. Показники ділової активності ТОВ «Стальконструкція» у 2019-2021 роках позитивно характеризують діяльність підприємства, а саме власний капітал використовується підприємством ефективно, спостерігаємо збільшення швидкості оборотності запасів, готової продукції, кредиторської заборгованості та зростання ефективності їх використання, що позитивно відображається на діловій активності підприємства. Зроблено висновки, що підприємству необхідно використовувати в своїй господарській діяльності більше позикових засобів довгострокового фінансування, що підвищить рентабельність власного капіталу.
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- 2023
21. Nonlinear frequency response curves estimation and stability analysis of randomly excited systems in the subspace framework
- Author
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D. Anastasio and S. Marchesiello
- Subjects
Applied Mathematics ,Mechanical Engineering ,nonlinear frequency ,periodic solution ,Aerospace Engineering ,Ocean Engineering ,harmonic balance ,nonlinear system identification ,continuation ,bifurcation ,stability ,Control and Systems Engineering ,Electrical and Electronic Engineering - Abstract
In this paper, the periodic solutions of nonlinear mechanical systems are studied starting from the nonlinear state-space model estimated using the nonlinear subspace identification (NSI) technique. In its standard form, NSI needs the input–output data from a nonlinear structure undergoing broadband excitation and requires the prior knowledge of the locations and kind of nonlinearities to be estimated. The method allows the estimation of the nonlinear features of the system and the indirect study of its periodic solutions using a single broadband excitation, without the need of feedback control loops. To this end, the nonlinear frequency response curves of the system are estimated merging the harmonic balance method with the NSI technique and using a continuation approach. Then, a monodromy-based stability analysis is developed in the nonlinear state-space framework to study the stability of the periodic solutions of the system and to track its bifurcations. The method is validated considering conservative nonlinearities on two numerical examples and one experimental application, the latter comprising a double-well oscillator with period-doubling phenomena. The effects of noise and nonlinear modeling errors are also evaluated.
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- 2023
22. Home First: Stability and Opportunity in Out-of-Home Care
- Author
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Steven Segal
- Subjects
out-of-home placement ,foster care ,Pharmacology (medical) ,stability - Abstract
In this report, the concept of “Home First” is introduced for those children who require long-term, non-kin placements. The term “Home First” connotes a placement engendering stability and continuity; this concept is introduced in conjunction with an evaluation of the historical, theoretical, and empirical evidence surrounding different forms of out-of-home placement, including group-care placements and foster family care. In light of these observations and studies, this report will argue that stability is a major factor, perhaps a necessary if not a sufficient condition, in successful child development. It will argue for the initiation of a new focus on the creation of long-term positive and stable residential placements within the out-of-home care system and show that such placements can and have contributed to the development of healthy, happy, and successful adulthoods. This report offers a bio-psycho-social perspective on child development in out-of-home care. It provides a brief overview of the multiple bio-psycho-social theoretical perspectives that inform us on the necessary role of stability in growth and development and the contribution of instability to dysfunction. This report considers stability in out-of-home care in relation to its associated outcomes and those factors believed to enhance or detract from these outcomes. It reviews the history of substitutive care provision for children and youth and the role of the “stability objective” in that history. Finally, it looks at how child welfare system priorities have influenced stability, and it offers some suggestions for ensuring more stable growth and development in child placement provision.
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- 2023
23. Adaptive potential of a watermelon collection for performance indicators
- Author
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Serhiienko, O.V., Linnik, Z.P., and Serhiienko, M.B.
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breeding ,plasticity ,watermelon ,breeding value ,collection accession ,General Medicine ,stability ,adaptive capacity ,breeding trait - Abstract
Purpose and Objectives. To select highly adaptable watermelon starting material by the main indicators of the performance (yield and average marketable fruit weight). Materials and Methods. The watermelon collection was investigated: 101 cultivars and lines from 9 countries (55 accessions from Ukraine, 23 - from Russia, 8 - from China, 5 - from the USA, 3 - from Moldova, 2 - from Kazakhstan, Thailand and the Czech Republic each, and 1 - from Italy). A Ukrainian cultivar, Maks Plus, was taken as the check accession. The following parameters were calculated: Vi - general adaptive capacity (GAC), σ2SACi - specific adaptive capacity (SAC), Sgi - genotype stability, bi - regression coefficient of the genotype's response to changing conditions (plasticity), and GBVi – genotype breeding value. AV Kilchevskyi and LV Khotylyova’s method was applied to estimate the parameters of adaptive capacity and stability of the genotypes. The environmental plasticity coefficients (bi) were calculated according to SA Eberhart and WA Russel algorithm. Data were statistically processed, as BA Dospekhov recommended. Results and Discussion. The adaptive potential of the watermelon collection was evaluated for the following traits: total yield, marketable yield, and average marketable fruit weight. The variation amplitude (Am) of the "total yield" trait based on the averaged three-year data on the collection was 51.26; the variation range was 15.07 - 66.33 t/ha. In the check accession, Maks Plus, the mean total yield across the 3 years was 64.72 t/ha. For further work, we selected 31 collection accessions, basing on the total yield” trait. The adaptability parameters of the collection watermelon accessions for the "marketable yield" trait differed somewhat from those for the “total yield” trait. From the averaged three-year data, the variation amplitude (Am) of the "marketable yield" trait was 51.15 t/ha; the variation range of this trait was 13.19 - 64.34 t/ha. The variation amplitude of the "average marketable fruit weight" trait based on the averaged three-year data was 3.00 kg. The variation range of this trait was 0.99–3.99 kg. The average fruit weight in the sample across the 3 years was 2.14 kg. In the check cultivar, Maks Plus, the average fruit weight was 2.50 kg. For the breeding for the characteristics under investigation, accessions of practical value, with high values of the general adaptive capacity, stability, and genotype breeding value were selected. By the environmental plasticity coefficient bi, the collection watermelon accessions were categorized as low-, mid- and highly plastic in terms of the characteristics under investigation: intensive accessions with enhanced responses to growing conditions, accessions with moderate levels of the environmental plasticity, and highly plastic accessions, which slightly respond to changes in growing conditions.
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- 2023
24. Nanonized carbamazepine for nose-to-brain delivery: pharmaceutical formulation development
- Author
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Angela Bonaccorso, Maria Rosa Gigliobianco, Rosamaria Lombardo, Rosalia Pellitteri, Piera Di Martino, Antonia Mancuso, and Teresa Musumeci
- Subjects
biocompatibility ,design of experiment ,Pharmaceutical Science ,nose-to-brain ,General Medicine ,stability ,Nanocrystals - Published
- 2023
25. Ecological plasticity and stability of promising lines of spring wheat (Triticum aestivum L.) in terms of yield
- Author
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Ye. A. Kuzmenko, M. V. Fedorenko, A. V. Pirych, and R. M. Blyzniuk
- Subjects
spring wheat ,productivity ,plasticity ,homeostatic ,breeding value ,General Medicine ,stability - Abstract
Purpose.To analyze lines of competitive testing of soft spring wheat in terms of ecological plasticity and stability using statistical methods of analysis and identify lines with high stability of grain yield. Methods.The studies were carried out during 2018–2020, on the basis of the V. M. Remeslo Myronivka Institute of Wheat NAAS of Ukraine. When considering the results obtained, generally accepted methodsof genetic and statistical analysis were used. Results.Evaluation of breeding material in different years makes it possible to obtain information about the characteristics of the reaction of genotypes to changes in environmental conditions. As a result of the studies, it was found that the lines Lutescens 14-32 (bi= 0.59), Erythrospermum 15-32 (bi= 0.44), Lutescens 14-47 (bi= 0.22) were of high plasticity. Calculations of ecological stability indicate that lines are considered stable, the variance of stability is zero or close to zero. From a practical point of view, lines with a combined manifestation of high ecological plasticity and stability are considered valuable. This was the line Erythrospermum 15-32 (bi= 0.44;S2di= 0.01) that indicates its low reaction rate and the ability to provide a consistently high level of yield under any growing conditions. The most valuable are the genotypes that combine a low level of the coefficient of variation, high homeostaticity and breeding value, which include the lines Erythrospermum 15-32 (Hom= 206.42,Sc= 4.11), Lutescens 14-47 (Hom= 98.41,Sc= 3.91), Erythrospermum 17-08 (Hom= 78.57,Sc=3.76), Erythrospermum 14-65 (Hom= 54.84,Sc= 3.75), Lutescens 14-32 (Hom= 54.60,Sc= 4.17), Lutescens 14-13 (Hom= 35.60,Sc= 3.78), Lutescens 14-48 (Hom= 46.66,Sc= 3.58). Conclusions.The evaluation of breeding material is of great importance when creating new high-performance varieties with adaptive potential. The method for assessing ecological plasticity and variants of its stability made it possible to differentiate wheat lines of soft spring competitive testing by their response to changes in growing conditions. For a more optimal selection of breeding material in terms of ecological plasticity and stability, breeding programs should take into account ranked estimates of genotypes.
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- 2023
26. Radical polymeric p-doping and grain modulation for stable, efficient perovskite solar modules
- Author
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Shuai You, Haipeng Zeng, Yuhang Liu, Bing Han, Min Li, Lin Li, Xin Zheng, Rui Guo, Long Luo, Zhe Li, Chi Zhang, Ranran Liu, Yang Zhao, Shujing Zhang, Qi Peng, Ti Wang, Qi Chen, Felix T. Eickemeyer, Brian Carlsen, Shaik M. Zakeeruddin, Liqiang Mai, Yaoguang Rong, Michael Grätzel, and Xiong Li
- Subjects
Multidisciplinary ,hysteresis ,growth ,impact ,cells ,films ,stability ,performance - Abstract
High-quality perovskite light harvesters and robust organic hole extraction layers are essential for achieving high-performing perovskite solar cells (PSCs). We introduce a phosphonic acid–functionalized fullerene derivative in mixed-cation perovskites as a grain boundary modulator to consolidate the crystal structure, which enhances the tolerance of the film against illumination, heat, and moisture. We also developed a redox-active radical polymer, poly(oxoammonium salt), that can effectively p-dope the hole-transporting material by hole injection and that also mitigates lithium ion diffusion. Power conversion efficiencies of 23.5% for 1-square-centimeter mixed–cation-anion PSCs and 21.4% for 17.1-square-centimeter minimodules were achieved. The PSCs retained 95.5% of their initial efficiencies after 3265 hours at maximum power point tracking under continuous 1-sun illumination at 70° ± 5°C.
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- 2023
27. Comparison of the Color Change of Porcelain Laminate Veneers Produced by Different Materials After Luting with Three Resin Cements
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Karaokutan, I, Aykent, F., and Özdoğan, M. S.
- Subjects
Surface ,Internal Fit ,Optical-Properties ,Mechanical-Properties ,Strength ,Translucency ,Thickness ,Stability ,Microstructure ,General Dentistry ,Exposure - Abstract
SUMMARYObjectivesThis study aimed to compare color change of porcelain laminate veneers fabricated with two lithium disilicate ceramics and a zirconia-reinforced lithium silicate ceramic material after luting with conventional dual-cure, amine-free dual-cure, or light-cure resin cements using artificial accelerated aging (AAA).Methods and MaterialsNinety noncarious human maxillary central incisors were embedded in autopolymerizing acrylic resin blocks to prepare conventional laminate veneers with incisal coverage. Prepared teeth were randomly divided into 3 groups (n=30) to fabricate laminate veneer restorations using: (1) lithium disilicate ceramic, (2) lithium disilicate ceramic with high-density micronization, and (3) zirconia-reinforced lithium silicate ceramic. Impressions of the preparations were taken with a laboratory scanner. Acquired 3D images were processed into a surface tessellation language file. Data were exported for 3D printing on a printer, and laminate veneers were printed in castable wax resin. Ceramic veneers were heat-pressed after investment according to the manufacturer’s recommendations and further divided into three groups (n=10) according to luting cement type: (1) light-cure resin cement, (2) amine-free dual-cure resin cement, and (3) conventional dual-cure resin cement. Color measurements were performed from the middle of each specimen with a spectrophotometer before and after AAA for 300 hours with a total energy of 150 kJ/m2. Color changes were calculated with the CIEDE 2000 (ΔE00) formula. Color differences were assessed using two-way analysis of variance (ANOVA) (α=0.05), and the paired t-test was used to compare the L*, a*, and b* parameters in each group before and after aging.ResultsThere were no significant differences between the ceramic groups (p>0.05). The color changes of the materials ranged from 2.26 to 3.13. All materials were above the clinically acceptable limit (ΔE00>1.8). The conventional dual-cure resin cement group showed more color change (p>0.05).ConclusionsColor changes were observed in all porcelain laminate veneers after artificial accelerated aging. The zirconia-reinforced lithium silicate veneers showed similar color changes as lithium disilicate veneers; the amine-free dual-cure resin cement showed a similar color change as light-cure resin cement after aging.
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- 2023
28. LTD 'STRŪŽĀNU SILTUMS’’ SOLVENCY ESTIMATION
- Author
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Jeršova, Klinta
- Subjects
General Medicine ,finance ,liquidity ,solvency ,stability - Abstract
In our time, the survival of the enterprise in the context of competition depends on its financial stability, therefore, it is important to conduct its financial analysis. Analysing the financial activities of the enterprise, it is necessary to conduct liquidity and solvency analysis. The study examines theoretical aspects of liquidity and solvency, as well as investigates and analyses Ltd “STRŪŽĀNU SILTUMS” liquidity and solvency coefficients, using graphic, monographic and documents analysis methods.
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- 2023
29. Accurate Small Sized Load Bearing Components Displacement Analysis
- Author
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MERCAN, Kadir
- Subjects
Engineering ,ANSYS ,Small cross section ,Stability ,Structural Steel ,Surface Elasticity ,Mühendislik ,General Medicine - Abstract
Load bearing components with cross sections in scale of millimeters attracted popularity with the advance in material engineering. As standard size scale of load bearing structures are around 100 times bigger than millimeter sized components, classical stability analyzes may be insufficient to simulate all stress and strains in load bearing structures which may lead to fail in whole structure. In this paper, the displacement analysis of small cross-sectional load bearing metals is presented using finite element analyzes and higher order elasticity theory. To take the size effect into consideration surface elasticity theory is selected. It is obtained higher order analyzes results differs from F.E.A. results. This result reveals that classical methods are insufficient to give accurate success in millimeters scale.
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- 2023
30. Effect of Aging and Cortical Stroke on Motor Adaptation to Overground Gait-Slips: Quantifying Differences in Adaptation Rate and Adaptation Plateau
- Author
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Rudri Purohit, Shuaijie Wang, and Tanvi Bhatt
- Subjects
General Medicine ,reactive balance ,stability ,motor adaptation ,fall prevention ,stroke ,aging - Abstract
We examined the effect of aging and cortical stroke on the rate of motor adaptation (adaptation rate) and amount of performance gains (adaptation plateau) in balance skills. Fourteen older (≥60 years) and fifteen younger ( 0.05). However, both stroke groups demonstrated a smaller adaptation plateau for the majority of reactive variables compared to healthy older adults (p < 0.05). The rate of adaptation to gait-slips does not slow with aging and cortical stroke; however, cortical stroke, age notwithstanding, may reduce performance gains in reactive balance skills, possibly hindering retention and transfer to real-life scenarios. People with stroke may need adjunctive therapies/supplemental agents to apply laboratory-acquired balance skills to daily life.
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- 2023
31. Instability of uracil in whole blood might affect cancer treatment with fluoropyrimidines
- Author
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Tybirk, Lea, Hoffmann-Lücke, Elke, and Greibe, Eva
- Subjects
Whole blood ,Preanalytical ,Dihydropyrimidine dehydrogrenase (DPD) deficiency ,Biochemistry (medical) ,Clinical Biochemistry ,5-fluorouracil ,General Medicine ,Uracil ,Stability ,Biochemistry - Abstract
Background and aims: Measurement of plasma uracil is used before cancer treatment with fluoropyrimidines to determine if patients tolerate a full dose. Incorrect preanalytical handling may cause falsely elevated concentration and result in suboptimal cancer treatment. We aimed to examine the stability of uracil in whole blood stored at room temperature (RT) and the effect of centrifugation temperature. Materials and methods: EDTA tubes (6x4 mL) were collected from 25 healthy volunteers. Five samples were stored 0, 1.5, 2, 3, and 4 h at RT and centrifuged at 4 °C. The sixth sample was centrifuged at RT after 1.5 h. Uracil was measured using an in-house LC-MS/MS method. Results: Storage of whole blood at RT followed by centrifugation at 4 °C caused a rapid increase in uracil concentration. Already after 1.5 h, the mean change (20.5 % (95 % CI: 11.9–29.2 %)) exceeded the maximum permissible difference. Centrifugation at RT instead of 4 °C after 1.5 h resulted in a smaller increase (7.0 % (95 % CI: 0.7–13.4 %)), although not statistically significant (p = 0.0527). Conclusion: Uracil was unstable in samples processed according to current recommendations. Our data indicates better stability when centrifugation is performed at RT compared with 4 °C but further research into this is necessary.
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- 2023
32. Adaptive Fuzzy Supplementary Controller for SSR Damping in a Series-Compensated DFIG-Based Wind Farm
- Author
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Mohamed Abdeen, Sayed Hosny Ahmed El-Banna, Sara Elgohary, Hend Mostafa, Nora Ghaly, Nourhan Adel, Zeinab Elkhwas, Mohamed Alahmady, Hossam M. Zawbaa, Salah Kamel, and European Union's Horizon 2020 Research and Enterprise Ireland through the Marie Sklodowska-Curie (Grant Number: 847402)
- Subjects
General Computer Science ,Electrical and Electronics ,Sub-synchronous resonance (SSR) ,General Engineering ,adaptive fuzzy supplementary controller ,General Materials Science ,gate-controlled series capacitor (GCSC) ,stability ,Electrical and Computer Engineering ,Electrical and Electronic Engineering - Abstract
Although using a series compensation technique in a long transmission line effectively increases the transmittable power; it may cause a sub-synchronous resonance (SSR) phenomenon. Gate-controlled series capacitor (GCSC) is an effective method for SSR damping by controlling the turn-off angle. In the previous studies, a constant supplementary damping controller (SDC) was used for controlling the turn-off angle, which can mitigate the SSR phenomenon. However, these methods can not capture the maximum transmittable power at different operating points. In this paper, a fuzzy logic controller (FLC) is proposed to compute the gain of SDC based on the wind speed and the error between the measured and reference line currents for transferring as much power as possible and damping the SSR phenomenon simultaneously. Using the MATLAB/SIMULINK program, the proposed method is tested at different operating points to validate its effectiveness and robustness. Compared to the traditional method (constant SDC), the maximum transmittable power, as well as SSR damping, is achieved in all studied cases by the proposed method (variable SDC).
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- 2023
33. Sedimentation and rheological behavior of reactive and non-reactive magnesium hydroxide pulps for industrial spray dryer processing
- Author
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E. C. Campos, D. H. S. Chaves, C. M. F. Santos, S. D. F. Rocha, and V. S. Birchal
- Subjects
Ceramics and Composites ,rheology ,structural particle arrangements ,sedimentation ,stability ,physical-chemical characterization - Abstract
Two different reactive concentrated magnesium hydroxide (HM) pulps, produced in a lab reactor mill, and a synthetic and non-reactive HM-pulp, for comparative analyses, have been prepared and studied. Sodium polyacrylate was selected as a dispersant for improving the HM pulp fluidity, with concentrations varying from 0.42% to 2.0% on a dry basis. The two reactive pulps differed from each other mainly by the impurity level and for both, a residual MgO amount was detected, implying that the hydration reaction could proceed. Results (with and without dispersant) confirmed the formation of particle clusters as HM concentration rose until a critical value, above which the pulp behaved as a solid. Reactive HM-pulps with high impurities may represent a limiting factor in the drying operation. Among all HM-pulps studied, the purest reactive pulp with 1% dispersant presented the best flow behavior making this reactive pulp the most suitable to be tested in a pilot spray dryer.
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- 2023
34. Stability Constraints on Reliability-Oriented Control of AC Microgrids – Theoretical Margin and Solutions
- Author
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Yubo Song, Subham Sahoo, Yongheng Yang, and Frede Blaabjerg
- Subjects
droop control ,Stability criteria ,reliability ,Power electronic systems ,power distribution ,Thermal stability ,AC Microgrids ,Microgrids ,stability ,Electrical and Electronic Engineering ,Stress ,Power system stability ,Reliability engineering - Abstract
Reliability is of importance for operation maintenance and cost reduction in power electronics and systems. Based on the reliability models of power devices, reliability-oriented power sharing in microgrids enforces the redistribution of power among converters to prolong the lifetime of the entire system, and droop control is typically used herein. However, this could affect the system stability, which contradicts the prerequisite of secure operation. In light of the above, this article is aimed to reveal this limitation of reliability-oriented droop control and emphasize its impact on system stability. Accordingly, a framework of stability-constrained reliability-oriented droop control is proposed, together with solutions that can help to enhance the stability. With this, the reliability of the system could be further improved without violating the stability criteria. Moreover, experimental tests and long-term reliability evaluations are included, which demonstrates that the aforementioned issues can be effectively addressed alongside with the proposed framework and solutions.
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- 2023
35. Parallel MPC for Linear Systems With State and Input Constraints
- Author
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Jiahe Shi, Yuning Jiang, Juraj Oravec, and Boris Houska
- Subjects
decomposition ,algorithm ,Control and Optimization ,recursive feasibility ,model predictive control ,parallel computing ,springs ,quadratic programming ,robustness ,stability ,real-time systems ,distributed mpc ,Optimization and Control (math.OC) ,Control and Systems Engineering ,model-predictive control ,standards ,FOS: Mathematics ,real-time control ,Mathematics - Optimization and Control ,prediction algorithms ,predictive control - Abstract
This letter proposes a parallelizable algorithm for linear-quadratic model predictive control (MPC) problems with state and input constraints. The algorithm itself is based on a parallel MPC scheme that has originally been designed for systems with input constraints. In this context, one contribution of this letter is the construction of time-varying yet separable constraint margins ensuring recursive feasibility and asymptotic stability of sub-optimal parallel MPC in a general setting, which also includes state constraints. Moreover, it is shown how to tradeoff online run-time guarantees versus the conservatism that is introduced by the tightened state constraints. The corresponding performance of the proposed method as well as the cost of the recursive feasibility guarantees is analyzed in the context of controlling a large-scale mechatronic system. This is illustrated by numerical experiments for a large-scale control system with more than 100 states and 60 control inputs leading to run-times in the millisecond range.
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- 2023
36. Probabilistic Risk Evaluation of Microgrids Considering Stability and Reliability
- Author
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Yubo Song, Subham Sahoo, Yongheng Yang, and Frede Blaabjerg
- Subjects
Stability criteria ,reliability ,Power electronic systems ,Uncertainty ,Thermal stability ,AC Microgrids ,Microgrids ,stability ,Electrical and Electronic Engineering ,Power system stability ,Probabilistic logic ,risk evaluation - Abstract
Microgrids are being developed with higher penetration of renewable energy sources (RES) and utilization of power electronics. The functionality of microgrids is normally measured by two indices, stability and reliability, which are highly influenced by system configuration and generation/load mission profiles. Although system-level modeling approaches have been proposed to evaluate both the said indices for microgrids, they are still considered independently due to the mismatch in their timescales. To this end, it limits the derivation of a comprehensive risk framework to exploit the interdependencies between stability and reliability. Hence, this article addresses this gap for the first time in the realm of microgrids by proposing a probabilistic risk framework by considering stability and reliability simultaneously. Long-timescale reliability are basically decomposed into shorter-timescale events, whereas stability is treated as probabilistic events to be integrated into the risk evaluation. This framework can quantify the operation risk of microgrids, thereby providing a more intuitive approach to the design of microgrids. To validate the ruggedness of the proposed framework, system stability and reliability are assessed and interpreted under experimental conditions.
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- 2023
37. Coupling of multiscale imaging analysis and computational modeling for understanding thick cathode degradation mechanisms
- Author
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Minghao Zhang, Mehdi Chouchane, S. Ali Shojaee, Bartlomiej Winiarski, Zhao Liu, Letian Li, Rengarajan Pelapur, Abbos Shodiev, Weiliang Yao, Jean-Marie Doux, Shen Wang, Yixuan Li, Chaoyue Liu, Herman Lemmens, Alejandro A. Franco, Ying Shirley Meng, Laboratoire réactivité et chimie des solides - UMR CNRS 7314 (LRCS), Université de Picardie Jules Verne (UPJV)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Réseau sur le stockage électrochimique de l'énergie (RS2E), Aix Marseille Université (AMU)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Collège de France (CdF (institution))-Université de Picardie Jules Verne (UPJV)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Université Grenoble Alpes (UGA)-Nantes Université (Nantes Univ)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), Université de Montpellier (UM), National Physical Laboratory [Teddington] (NPL), School of Materials [Manchester], University of Manchester [Manchester], Institute of Metal Research [Chinese Academy of Sciences] (IMR), Chinese Academy of Sciences [Beijing] (CAS), University of Missouri [Columbia] (Mizzou), University of Missouri System, University College Dublin [Dublin] (UCD), Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Advanced Lithium Energy Storage Systems - ALISTORE-ERI (ALISTORE-ERI), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
LITHIUM METAL ,SULFONE ,General Energy ,STABILITY ,TOMOGRAPHY ,BATTERY ELECTRODES ,CARBONATE ,INSIGHT ,[CHIM.MATE]Chemical Sciences/Material chemistry ,ELECTROLYTE INTERPHASE ,CHARGE - Abstract
International audience; Using a thick NMC811 (LiNi0.8Mn0.1Co0.1O2) electrode as an example, we present a macro-to nanoscale 2D and 3D imaging analysis approach coupled with 4D (space + time) computational modeling to probe its degradation mechanism in a lithium-ion bat-tery cell. Particle cracking increases and contact loss between parti-cles and carbon-binder domain are observed to correlate with the cell degradation. This study unravels that the reaction heterogene-ity within the thick cathode caused by the unbalanced electron con-duction is the main cause of the battery degradation over cycling. The increased heterogeneity in the system will entail more cathode regions where the degree of active material utilization is uneven, leading to higher probabilities of particle cracking. These findings shed light on the crucial role of the electronic and ionic transporta-tion networks in the performance deterioration of the thick cathode. They also provide guidance for cathode architecture optimization and performance improvement.
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- 2023
38. Design principles for transition metal nitride stability and ammonia generation in acid
- Author
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Jiayu Peng, Juan J. Giner-Sanz, Livia Giordano, William P. Mounfield, Graham M. Leverick, Yang Yu, Yuriy Román-Leshkov, Yang Shao-Horn, Peng, J, Giner-Sanz, J, Giordano, L, Mounfield, W, Leverick, G, Yu, Y, Román-Leshkov, Y, and Shao-Horn, Y
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General Energy ,electrocatalysi ,descriptor ,dissolution ,transition metal nitride ,stability ,ammonia ,energy - Abstract
Transition metal nitrides have shown promise as electrocatalysts in proton exchange membrane fuel cells and electrolyzers, but the instability of these nitrides in acid has limited their function for such technologies. On the other hand, having fast, complete nitride dissolution and ammonia formation in acid can offer new opportunities for distributed, on-demand ammonia generation. Optimizing nitride chemistries for these clean energy applications requires design principles for nitride dissolution and ammonia formation in acid. Here, we report that lowering the nitrogen 2p band center of transition metal nitrides relative to the Fermi level weakens metal–nitrogen bonds and increases labile metallic character, reducing dissolution reaction barriers and boosting ammonia formation kinetics in acid. Increasing the solubility of dissolved metal cations further facilitates the decomposition of nitrides in acid by prohibiting surface oxide passivation. These findings highlight essential future directions for preventing nitride dissolution or facilitating ammonia production for diverse acidic applications.
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- 2023
39. A note on the wave equation controlled with a dynamic saturating boundary control
- Author
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Gauvrit, Mario, Prieur, Christophe, Tarbouriech, Sophie, Ecole Normale Supérieure Paris-Saclay (ENS Paris Saclay), GIPSA - Infinite Dimensional Dynamics (GIPSA-INFINITY), GIPSA Pôle Automatique et Diagnostic (GIPSA-PAD), Grenoble Images Parole Signal Automatique (GIPSA-lab), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Grenoble Images Parole Signal Automatique (GIPSA-lab), Université Grenoble Alpes (UGA), Équipe Méthodes et Algorithmes en Commande (LAAS-MAC), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT), Jochen Trumpf, Robert Mahony, and ANR-19-P3IA-0003,MIAI,MIAI @ Grenoble Alpes(2019)
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well-posedness ,Control and Systems Engineering ,saturation ,Infinite-dimensional systems ,stability ,[SPI.AUTO]Engineering Sciences [physics]/Automatic - Abstract
International audience; This paper studies the nonlinear systems obtained by considering a wave equation in closed loop with a nonlinear dynamical boundary controller. The controller is subject to a magnitude limitation and modeled by a linear ordinary differential equation with a saturation map in the input. The well-posedness of the obtained infinite-dimensional system is first studied and then two stability results are given. These two stability results apply for two cascade cases and give sufficient conditions for the asymptotic stability of the equilibrium. The well-posedness is proven by using nonlinear semigroups techniques, whereas the global asymptotic stability results are obtained by Lyapunov-based arguments in infinite-dimensional state space.
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- 2023
40. Qualitative study of a second order difference equation
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Berkal, Messaoud, Navarro, Juan F., Universidad de Alicante. Departamento de Matemática Aplicada, and Geodesia Espacial y Dinámica Espacial
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Difference equations ,General Mathematics ,Neimark-Sacker bifurcation ,Stability - Abstract
In this paper, we study a second order rational difference equation. We analyze the stability of the unique positive equilibrium of the equation and prove the existence of a Neimark-Sacker bifurcation, validating our theoretical analysis via a numerical exploration of the system.
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- 2023
41. Cocoa Shell as an Innovative Ingredient in Chocolate with a Strong Alcoholic Filling
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Mirela Trgovac, Ivana Flanjak, Đurđica Ačkar, Drago Šubarić, Jurislav Babić, Borislav Miličević, Antun Jozinović, and Veronika Barišić
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chocolate ,alcoholic filling ,bitter herbal liqueur ,sensory acceptability ,stability ,General Medicine - Abstract
he chocolate industry is constantly developing new products with different fillings, toppings, flavours, etc. Chocolates with alcoholic filling are popular, especially with young adults. In chocolates with alcoholic filling different kinds of thickeners can be used to increase the viscosity of the filling and make production easier. In this study, we examined cocoa shells, a by-product of the chocolate industry, as a new ingredient and thickener of an alcoholic filling. Chocolates with bitter herbal liqueur were produced in a ball mill with four different fillers. A comparison of guar gum and cocoa shell as thickeners was conducted. The influence of the filling ingredients on the stability of the filled chocolate was determined by measuring colour and gloss over 30 days of accelerated fat bloom. The results showed that chocolates for which the cocoa shell was used were more stable than chocolates where guar gum was used. Evaluation of sensory properties of chocolates with bitter herbal liqueur and different thickeners was conducted by the trained sensory panel. The highest-rated, after sensory assessment, were dark chocolates that contained cocoa shells in the filling. Also, an online questionnaire was conducted to examine consumer preference for a new product. According to the results, it can be concluded that the production of this chocolate would be desirable.
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- 2022
42. Determination of 2,4-dichlorophenoxyacetic acid in water, sediment and soil using high performance liquid chromatography
- Author
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James, Stella, Ele Yaya, Estifanos, Singh Chandravanshi , Bhagwan, and Zewge, Feleke
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Soil ,Lake Koka ,2,4-Dichlorophenoxyacetic acid ,Water ,Sediment ,General Chemistry ,Stability - Abstract
The purpose of this study was to develop a method for the extraction and determination of 2,4-dichlorophenoxyacetic acid (2,4-D) from the soil, sediment, and water, and to investigate its stability in water using high-performance liquid chromatography (HPLC). The recoveries of the spiked compound from water and soil samples was found to be in the range of 80 to 100%. The yield of 2,4-D during acidification of the corresponding amine was 93.84-99.98%. A calibration curve for the method showed good linearity (R2 ≥ 0.9996). The LOD was determined to be 0.45 µg/mL while the LOQ was 2 µg/mL. From the analysis of the samples, 2,4-D was not detected in sediment or soil samples from the Wafiko or Kontola sites (Ethiopia), respectively. The 2,4-D concentrations in soil samples from Bochessa, and water samples from Wafiko and Sher sites (Ethiopia) were high, ranging from 68.22 to 167.7 mg/L which exceeded the United States Environmental Protection Agency (US EPA) regulatory agency standards of 70 µg/L. A 45-day experiment on spiked water samples from Lake Koka (Ethiopia) demonstrated that the acidic form of 2,4-D is stable in water with 73.46 ± 2.00% recoveries. The developed method can be used to determine 2,4-D residues in soil, sediment, and water. KEY WORDS: 2,4-Dichlorophenoxyacetic acid, Lake Koka, Sediment, Soil, Stability, Water Bull. Chem. Soc. Ethiop. 2023, 37(2), 251-263. DOI: https://dx.doi.org/10.4314/bcse.v37i2.1  
- Published
- 2022
43. Chemical Stability of Petrichorins
- Author
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Chunshun Li, Ariel M. Sarotti, Antonio Hernández Daranas, Xiaohua Wu, Shao-Liang Zheng, Joshua A. V. Blodgett, Shugeng Cao, Inouye College of Pharmacy, University of Hawaii, Universidad Nacional de Rosario (Argentina), Agencia Nacional de Promoción Científica y Tecnológica (Argentina), Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), and National Science Foundation (US)
- Subjects
Organic Chemistry ,Chemical ,stability ,petrichorins - Abstract
The structure of petrichorin C1 (4) converted from petrichorin C (3) was determined using NMR spectroscopy and X-ray crystallography. The chemical stability of petrichorins A and C (1 and 3) was investigated by NMR spectroscopy, X-ray crystallography, and calculations., This work was financially supported by a start-up funding from Daniel K. Inouye College of Pharmacy (DKICP), Seed Grants from University of Hawaii at Hilo (UHH) to SC. We also acknowledge UNR (BIO 567), ANPCyT (PICT-2017-1524), and CONICET for financial support to AMS. This work was partially supported by NSF-CAREER 1846005 to JB.
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- 2022
44. Conversion of Lithium Chloride into Lithium Hydroxide by Solvent Extraction
- Author
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Sofía Riaño, Koen Binnemans, Ward Caytan, Clio Deferm, Viet Tu Nguyen, and Peter Tom Jones
- Subjects
Technology ,Science & Technology ,Solvent extraction ,MONOHYDRATE ,STABILITY ,CHLORINATION ,PHASE-TRANSFER CATALYSIS ,Metals and Alloys ,Aliquat 336 ,Lithium ,RECOVERY ,Environmental Science (miscellaneous) ,EXTRACTABILITY ,MEDIA ,Antisolvent precipitation ,Mechanics of Materials ,BETA-SPODUMENE ,DILUENT ,Hydrometallurgy ,SEPARATION ,Science & Technology - Other Topics ,Metallurgy & Metallurgical Engineering ,Green & Sustainable Science & Technology ,Ion exchange - Abstract
UNLABELLED: A hydrometallurgical process is described for conversion of an aqueous solution of lithium chloride into an aqueous solution of lithium hydroxide via a chloride/hydroxide anion exchange reaction by solvent extraction. The organic phase comprises a quaternary ammonium chloride and a hydrophobic phenol in a diluent. The best results were observed for a mixture of the quaternary ammonium chloride Aliquat 336 and 2,6-di-tert-butylphenol (1:1 molar ratio) in the aliphatic diluent Shellsol D70. The solvent extraction process involves two steps. In the first step, the organic phase is contacted with an aqueous sodium hydroxide solution. The phenol is deprotonated, and a chloride ion is simultaneously transferred to the aqueous phase, leading to in situ formation of a quaternary ammonium phenolate in the organic phase. The organic phase, comprising the quaternary ammonium phenolate, is contacted in the second step with an aqueous lithium chloride solution. This contact converts the phenolate into the corresponding phenol by protonation with water extracted to the organic phase, followed by a transfer of hydroxide ions to the aqueous phase and chloride ions to the organic phase. As a result, the aqueous lithium chloride solution is transformed into a lithium hydroxide solution. The process has been demonstrated in continuous counter-current mode in mixer-settlers. Solid battery-grade lithium hydroxide monohydrate was obtained from the aqueous solution by crystallization or by antisolvent precipitation with isopropanol. The process consumes no chemicals other than sodium hydroxide. No waste is generated, with the exception of an aqueous sodium chloride solution. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40831-022-00629-2. ispartof: JOURNAL OF SUSTAINABLE METALLURGY vol:9 issue:1 pages:107-122 ispartof: location:Netherlands status: published
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- 2022
45. Sulfonic Acid Derivatives in the Production of Stable Co-Amorphous Systems for Solubility Enhancement
- Author
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Nuno F. da Costa, Inês A. Santos, Ana I. Fernandes, and João F. Pinto
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Saccharin ,Solubility ,Olanzapine ,Carboxylic acids ,Sulfonic acid derivatives ,Pharmaceutical Science ,Salts ,Sulfonic Acids ,Co-amorphous systems ,Stability - Abstract
"Co-amorphization is a promising approach to stabilize drugs in the amorphous form. Olanzapine, a poorly water-soluble drug was used in this study. Sulfonic acids (saccharin, cyclamic acid and acesulfame), free and in salt forms, were used as co-formers and compared with carboxylic acids commonly used in the preparation of co-amorphous systems. Several manufacturing techniques were tested, and the co-amorphous systems characterized by differential scanning calorimetry, X-ray powder diffraction, thermogravimetry and Fourier-transform infrared spectroscopy. Free sulfonic acids produced co-amorphous systems with the drug, unlike their salts. Spectroscopy data suggests the formation of salts between olanzapine and the sulfonic acids, used as co-formers. The co-amorphous system produced with saccharin by solvent evaporation, showed the most notable solubility enhancement (145 times). The stability of amorphous and co-amorphous olanzapine systems was assessed upon exposure to stress conditions during storage. Amorphized olanzapine readily reconverted back to the crystalline form while sulfonic acids:olanzapine co-amorphous were stable for up to 24 weeks in low/medium humidity conditions (11-75% RH). Results highlight the potential advantages offered by sulfonic acids as co-formers to produce stable and more soluble co-amorphous olanzapine." info:eu-repo/semantics/publishedVersion
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- 2022
46. Artificial Neural Network-Based Pole-Tracking Method for Online Stabilization Control of Grid-Tied VSC
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Chen Zhang, Nenad Mijatovic, Xu Cai, and Tomislav Dragicevic
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Artificial neural network (ANN) ,Control and Systems Engineering ,Impedance ,Voltage source converter (VSC) ,Electrical and Electronic Engineering ,Poletracking ,Stability ,Stabilization control - Abstract
To cope with the weak grid stability issue of grid-tied Voltage Source Converters (VSCs), this letter proposes an Artificial Neural Network (ANN)-based approach for online stabilization control of the grid-tied VSC with the pole-tracking feature. First, an ANN is adopted to establish the mapping between the control parameters and the closed-loop poles of the grid-VSC system, serving as a computationally light model surrogate that is favorable for real-time control applications. Then, an online parameter search algorithm enabling simultaneous tuning of multiple controllers and parameters is developed, by which the systems poles under a new grid condition can be pulled to the reference ones, i.e., achieving the pole-tracking-based stabilization control of this work. Finally, the efficacy of the proposed method along with its stabilization effect is verified by MATLAB simulations and experimental results.
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- 2022
47. Control and Stability Analysis of Current-Controlled Grid-Connected Inverters in Asymmetrical Grids
- Author
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Ali Akhavan, Josep Guerrero, Juan C. Vasquez, and Saeed Golestan
- Subjects
Control systems ,Stability criteria ,Impedance ,interaction ,Inverters ,stability ,Damping ,Power system stability ,MIMO system ,grid-connected inverters ,multi-input multioutput (MIMO) system ,MIMO communication ,Asymmetrical grids ,Electrical and Electronic Engineering - Abstract
In symmetrical grids, single-input single-output (SISO) analysis/design tools are applicable for the analysis and design of grid-tied inverter systems as their average αβ-or dq-frame models are to a high extent decoupled (in the high-frequency range). In this way, designing the control system could be done in a straightforward manner. However, this is not the case under asymmetrical grids. In this condition, the interaction between different phases makes the average model of the grid-tied inverter a multi-input multioutput (MIMO) system, and therefore, complicated to analyze and design. To cope with this challenge, this article deals with deriving the MIMO control system considering the impact of the asymmetrical grid. Then, the MIMO system turns into two decoupled SISO systems. Thus, a simple yet accurate model is developed which intuitively demonstrates the effect of the grid asymmetry on creating coupling between current control loops. In this way, the stability analysis could be carried out irrespective of the MIMO system difficulties. The experimental results validate the accuracy of the proposed approach in asymmetrical grid conditions.
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- 2022
48. Amino-Alkylphosphonate-Grafted TiO2: How the Alkyl Chain Length Impacts the Surface Properties and the Adsorption Efficiency for Pd
- Author
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Nick Gys, Rui An, Bram Pawlak, David Vogelsang, Kenny Wyns, Kitty Baert, Alexander Vansant, Frank Blockhuys, Peter Adriaensens, Tom Hauffman, Bart Michielsen, Steven Mullens, and Vera Meynen
- Subjects
PLATINUM ,Science & Technology ,STABILITY ,PALLADIUM ,Chemistry, Multidisciplinary ,General Chemical Engineering ,OXIDE ,General Chemistry ,ACIDS ,PHOSPHONATE MONOLAYERS ,Chemistry ,SELF-ASSEMBLED MONOLAYERS ,AMINOPROPYL GROUPS ,Physical Sciences ,NANOPARTICLES ,FUNCTIONALIZATION - Abstract
Amino-alkylphosphonic acid-grafted TiO2 materials are of increasing interest in a variety of applications such as metal sorption, heterogeneous catalysis, CO2 capture, and enzyme immobilization. To date, systematic insights into the synthesis-properties-performance correlation are missing for such materials, albeit giving important know-how towards their applicability and limitations. In this work, the impact of the chain length and modification conditions (concentration and temperature) of amino-alkylphosphonic acid-grafted TiO2 on the surface properties and adsorption performance of palladium is studied. Via grafting with aminomethyl-, 3-aminopropyl-, and 6-aminohexylphosphonic acid, combined with the spectroscopic techniques (DRIFT, 31P NMR, XPS) and zeta potential measurements, differences in surface properties between the C1, C3, and C6 chains are revealed. The modification degree decreases with increasing chain length under the same synthesis conditions, indicative of folded grafted groups that sterically shield an increasing area of binding sites with increasing chain length. Next, all techniques confirm the different surface interactions of a C1 chain compared to a C3 or C6 chain. This is in line with palladium adsorption experiments, where only for a C1 chain, the adsorption efficiency is affected by the precursor concentration used for modification. The absence of a straightforward correlation between the number of free NH2 groups and the adsorption capacity for the different chain lengths indicates that other chain-length-specific surface interactions are controlling the adsorption performance. The increasing pH stability in the order of C1 < C3 < C6 can possibly be associated to a higher fraction of inaccessible hydrophilic sites due to the presence of folded structures. Lastly, the comparison of adsorption performance and pH stability with 3-aminopropyl(triethoxysilane)-grafted TiO2 reveals the applicability of both grafting methods depending on the envisaged pH during sorption. ispartof: ACS OMEGA vol:7 issue:49 pages:45409-45421 ispartof: location:United States status: published
- Published
- 2022
49. Initial formation of channel–shoal patterns in double–inlet systems
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Xiao Deng, Tom De Mulder, and Henk Schuttelaars
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Technology and Engineering ,Double-inlet systems ,MORPHODYNAMIC EQUILIBRIA ,SEA ,STABILITY ,Channels and shoals ,FLOW ,SEDIMENT ,Oceanography ,TRANSPORT ,LONG-TERM EVOLUTION ,MODEL ,Linear stabilities ,BARRIER ISLANDS - Abstract
Channel-shoal patterns are often observed in the back-barrier basins of inlet systems and are important from both an economical and ecological point of view. Focussing on double-inlet systems, the initial formation of these patterns is investigated using an idealized model. The model is governed by the depth-averaged shallow water equations, a depth-integrated concentration equation and a tidally-averaged bottom evolution equation. Focussing on rectangular basins and neglecting the effects of earth rotation, it is found that laterally uniform morphodynamic equilibria can become linearly unstable, resulting in initial patterns that resemble channels and shoals. When the water motion is only forced by an M-2 tidal constituent, the existence of (laterally uniform) morphodynamic equilibria for which both inlets are connected strongly depends on the relative phase and amplitudes of the tidal forcing. If such equilibria exist, they can be either stable against small perturbations or linearly unstable. If these equilibria are linearly unstable, two instability mechanisms can be identified, the first related to the convergences and divergences of diffusive transports, the second mechanism related to a combination of advective and diffusive transports. In the former case, all eigenvalues are real and the bedforms grow exponentially in time. In the latter case, the eigenvalues are complex, resulting in bedforms that both migrate and grow in time. In case external overtides and a time-independent discharge are included, no diffusive instabilities are found anymore for the parameters considered in this paper. This implies that all instabilities are migrating in time. In all cases considered, the bed perturbations have only an appreciable amplitude at locations where the underlying laterally uniform equilibrium has a local minimum in water depth. This is consistent with observations from numerical models and laboratory experiments.
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- 2022
50. Fabrication and Characteristic of Rhamnolipid-chitosan Coated Emulsions for Loading Ergocalciferol
- Author
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Ma, Zhaoxiang, Sun, Cuixia, Chen, Zhang, and Zhao, Yiguo
- Subjects
Chitosan ,Ergocalciferol ,Layer-by-layer emulsions ,Rhamnolipids ,Biophysics ,Bioengineering ,Environmental stress ,Stability ,Applied Microbiology and Biotechnology ,Food Science ,Analytical Chemistry - Abstract
To overcome the intrinsic limitations of ergocalciferol, layer-by-layer oil-in-water emulsions were formulated and applied in the microencapsulation of ergocalciferol. The primary emulsions were prepared using rhamnolipids to stabilize oil droplets, and then the secondary emulsions were formed by electrostatic deposition of cationic chitosan onto anionic rhamnolipids-coated droplets. The effects of pH, ionic strength, and thermal treatment on the stability of emulsions were investigated. Secondary emulsions were more stable than primary emulsions at low pH and high NaCl concentrations. Both emulsions showed excellent physicochemical stability during long-term storage. The droplet size of emulsions remained stable, and the ergocalciferol retention in emulsions was still maintained at over 95% after 30 days of storage. These results indicate that the resistance of prepared emulsions to different environmental stresses is enhanced. Moreover, this study gives important information for extending the utilization of rhamnolipids and chitosan in the delivery system for functional ingredients.
- Published
- 2022
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