Articles de revues : « Dynamical filtrations »

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Bartłomiejczyk, P., et Z. Dzedzej. « Index filtrations and Morse decompositions for discrete dynamical systems ». Annales Polonici Mathematici 72, n^o 1 (1999) : 51–70. http://dx.doi.org/10.4064/ap-72-1-51-70.

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Gordin, M. I. « Double extensions of dynamical systems and constructing mixing filtrations ». Journal of Mathematical Sciences 99, n^o 2 (avril 2000) : 1053–60. http://dx.doi.org/10.1007/bf02673626.

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Jiao, Rui, Wei Liu et Yijun Hu. « The Optimal Consumption, Investment and Life Insurance for Wage Earners under Inside Information and Inflation ». Mathematics 11, n^o 15 (5 août 2023) : 3415. http://dx.doi.org/10.3390/math11153415.

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This paper studies the dynamically optimal consumption, investment and life-insurance strategies for a wage earners under inside information and inflation. Assume that the wage earner can invest in a risk-free asset, a risky asset and an inflation-indexed bond and that the wage earner can obtain some additional information on the risky asset from the financial market. By maximizing the expected utility of the wage earner’s consumption, inheritance and terminal wealth, we obtain the dynamically optimal consumption, investment and life-insurance strategies for the wage earner. The method of this paper is mainly based on (dynamical) stochastic control theory and the technique of enlargement of filtrations. Moreover, sensitivity analysis is carried out, which reveals that a wage earner with inside information tends to increase his/her consumption and investment, while reducing his/her purchase of life insurance.

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KCHIA, YOUNES, et PHILIP PROTTER. « PROGRESSIVE FILTRATION EXPANSIONS VIA A PROCESS, WITH APPLICATIONS TO INSIDER TRADING ». International Journal of Theoretical and Applied Finance 18, n^o 04 (juin 2015) : 1550027. http://dx.doi.org/10.1142/s0219024915500272.

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The development of the theory of the expansion of filtrations took place mostly three decades ago, in the 1980s. Researchers developed two types of expansions: Initial expansions, where one adds information to the σ algebra ℱ0, and progressive expansions, where information is added dynamically to turn a positive random variable (such as a last exit time) into a stopping time. The goal was to preserve the semimartingale property in the enlarged filtration. In this paper, we propose a new type of expansion, that of expansion with a stochastic process. This has antecedents in the work of Jeulin, Kohatsu-Higa, and a few others, but the theoretical and systematic approach given here is new. We begin by showing one can enlarge a filtration with a point process rather easily, and that semimartingales remain semimartingales under the expansions, if done correctly. Since one can approximate most stochastic processes with marked point processes, we then prove convergence theorems of the sequence of point processes together with their corresponding enlarged filtrations. To do this, we rely on a theory of the convergence of filtrations. We next need to give conditions such that semimartingales remain semimartingales in the limit. This is delicate, and we obtain partial results, but they are sufficient for our needs; this involves a kind of continual initial expansion procedure. One drawback of this procedure is that we do not always obtain the semimartingale decompositions for the enlarged filtrations of the limiting case, except in a class of examples that are in a Brownian motion paradigm. Recently, there have been attempts to model mathematically insider trading via a theory of enlarged filtrations. There are many technical issues involved, and creating a model with the presence of arbitrage is a constant problem, a situation one wishes to avoid. We show how one can use this procedure to create models of insider trading that do not have arbitrage opportunities, but under which the risk neutral measure for the insider is different than is the risk neutral measure for the rest of the market.

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Atamanyuk, Volodymyr, et Yaroslav Gumnytskyi. « Mass Exchange Dynamics During the Second Filtration Drying Period ». Chemistry & ; Chemical Technology 3, n^o 2 (15 juin 2009) : 129–37. http://dx.doi.org/10.23939/chcht03.02.129.

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The work is dedicated to theoretical and experimental investigations of kinetics and dynamics of filtration drying of capillary and pore materials, and mineral granulated fertilizers, in particular. The proposed physical model of a moist particle and the differential system of equations which describes heat exchange in the second drying period enables to determine the transfer velocity of mass-exchange zone in a dispersion layer of the material during filtration drying.

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Razvan, M. R. « On Conley's fundamental theorem of dynamical systems ». International Journal of Mathematics and Mathematical Sciences 2004, n^o 26 (2004) : 1397–401. http://dx.doi.org/10.1155/s0161171204202125.

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Savrassov, Ju S. « Algorithms of filtration and extrapolation for discrete-time dynamical systems ». Acta Applicandae Mathematicae 30, n^o 3 (mars 1993) : 193–263. http://dx.doi.org/10.1007/bf00995471.

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Duda, Zdzisław. « Hierarchical filtration for distributed linear multisensor systems ». Archives of Control Sciences 22, n^o 4 (1 décembre 2012) : 507–18. http://dx.doi.org/10.2478/v10170-011-0038-7.

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In the paper two filtration algorithms for distributed multisensor system are presented. The first one is derived for a linear dynamical system composed of local subsystems described by local state equations. Local estimates are sent to a central station to be fused and formed an optimal global estimate. The second algorithm is derived for a system observed by local nodes that determine estimates of the whole system using local information and periodically aggregated information from other nodes. Periodically local estimates are sent to the central station to be fused. Owing to this a reduced communication can be achieved

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H.Z, Igamberdiev, et Kholodzhayev B.A. « ALGORITHMS FOR SUSTAINABLE RECOVERY OF INPUT INFLUENCE ON THE BASIS OF DYNAMIC FILTRATION METHODS ». International Journal of Psychosocial Rehabilitation 24, n^o 03 (18 février 2020) : 232–39. http://dx.doi.org/10.37200/ijpr/v24i3/pr200774.

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Bang, Jong-Geun, et Yoong-Sup Yoon. « Analysis of Filtration Performance by Brownian Dynamics ». Transactions of the Korean Society of Mechanical Engineers B 33, n^o 10 (1 octobre 2009) : 811–19. http://dx.doi.org/10.3795/ksme-b.2009.33.10.811.

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Mahamadou Harouna, Bassirou, Othmane Benkortbi, Salah Hanini et Abdeltif Amrane. « Modeling of transitional pore blockage to cake filtration and modified fouling index – Dynamical surface phenomena in membrane filtration ». Chemical Engineering Science 193 (janvier 2019) : 298–311. http://dx.doi.org/10.1016/j.ces.2018.07.054.

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Jasiński, Bartłomiej. « Określenie dynamicznej filtracji płuczek wiertniczych w warunkach HPHT z użyciem nowatorskiej metody pomiarowej ». Nafta-Gaz 74, n^o 2 (février 2018) : 85–95. http://dx.doi.org/10.18668/ng.2018.02.02.

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Afanasyev, Y. D., et E. K. Demirov. « A variational filtration and interpolation technique for PIV employing fluid dynamical constraints ». Experiments in Fluids 39, n^o 5 (26 juillet 2005) : 828–35. http://dx.doi.org/10.1007/s00348-005-0017-5.

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Wang, Hao, Junfei Wu, Ping Fu, Zhiping Qu, Wenjie Zhao et Yixuan Song. « CFD-DEM Study of Bridging Mechanism of Particles in Ceramic Membrane Pores under Surface Filtration Conditions ». Processes 10, n^o 3 (26 février 2022) : 475. http://dx.doi.org/10.3390/pr10030475.

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In the surface filtration process with pores larger than the particle size, the formation of particle bridges plays a crucial role in the filter cake structure and the filtration efficiency throughout the filtration process. First, to understand the microscopic information required for the bridging mechanism, we use the two-way coupling of computational fluid dynamics (CFD)–discrete element method (DEM) to simulate the deposition characteristics of particles in the pores of ceramic membranes. Next, by dynamically observing the deposition morphology and bridging process of particles, the bridging mechanism was revealed at the level of a single hole. Then, we studied the influence of particle concentration and inlet velocity on the bridge erection process. The results show that the bridging function of particles runs through the clean filtration stage and the transition stage. Particle concentration and inlet flow rate have a crucial influence on the formation of particle bridges and filtration efficiency.

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Boychuk, Leonid M. « Two Approaches to the Structural Synthesis of Control Systems : Dynamical Filtration and Automatic Compensation ». Journal of Automation and Information Sciences 30, n^o 6 (1998) : 13–22. http://dx.doi.org/10.1615/jautomatinfscien.v30.i6.20.

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Gotfredsen, Anders, Lene Bæksgaard et And Jannik Hilsted. « Body composition analysis by DEXA by using dynamically changing samarium filtration ». Journal of Applied Physiology 82, n^o 4 (1 avril 1997) : 1200–1209. http://dx.doi.org/10.1152/jappl.1997.82.4.1200.

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Gotfredsen, Anders, Lene Bæksgaard, and Jannik Hilsted.Body composition analysis by DEXA by using dynamically changing samarium filtration. J. Appl. Physiol.82(4): 1200–1209, 1997.—Dual-energy X-ray absorptiometry (DEXA) has a high accuracy for body composition analysis but is influenced by beam hardening and other error sources in the extremes of measurement. To compensate for beam hardening, the Norland XR-36 introduces a dynamically changing samarium filtration system, which depends on the current-absorber thickness. With this system we found a good agreement ( r = 0.99) between reference and measured amounts of tissue or fat percentages in a plastic phantom and in smaller (∼0.5–4 kg) and larger (∼5–20 kg) piles of tissue (ox muscle and lard). Scans of six healthy volunteers covered with combinations of beef and lard (∼5–15 kg) showed a good agreement ( r = 0.99) between reference and DEXA values of added soft tissue mass and fat percentage. We conclude that the DEXA method (and, in particular, the Norland XR-36 using dynamic filtration) has a high accuracy for body composition analysis. It has a potential for gaining status as a reference method in the future and may presently be used as a supplement to the traditional methods for body composition analysis.

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Pongsumpun, Puntipa, et Puntani Pongsumpun. « The Simulation Model of Dengue Transmission by Gender of Human in Thailand ». International Journal of Membrane Science and Technology 10, n^o 4 (30 septembre 2023) : 1319–31. http://dx.doi.org/10.15379/ijmst.v10i4.2246.

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Dengue disease can be transmitted to human by the biting of infected Aedes aegypti mosquitoes. This disease has 4 serotypes such as DEN-1, DEN-2, DEN-3 and DEN-4. The symptoms of this disease are high fever, headache, body aches, nausea and rash. This paper describes the spread of this disease by formulating the dynamical model between human and mosquito populations. The human are separating into man and woman populations. The standard dynamical modelling method is used to analyze our dynamical model. The numerical solutions are presented. The basic reproduction value of the disease is found. The way for reducing the transmission of this disease is introduced.

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Kostyuchenko, S. V., et N. A. Cheremisin. « Dynamic phase permeability for calculating oil locations in digital models ». Oil and Gas Studies, n^o 5 (31 octobre 2021) : 168–76. http://dx.doi.org/10.31660/0445-0108-2021-5-168-176.

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The article presents the author's formulas for calculating the residual oil saturation and the end points of relative phase permeabilities that dynamically depend on the filtration rate of reservoir fluids and capillary numbers. The dependences of the residual oil saturation and the end points of the phase permeabilities on the capillary number are investigated and described. An element of a five-point system for the development of an oil deposit case study shows the possibility of calculating oil targets using dynamic phase permeabilities. The difference between the model with static relative phase permeabilities and the model with dynamic phase permeabilities should be stressed. The text gives valuable information on the dependence of the simulation results on the parameters of the nonlinearity of the filtration processes with the traditional filtration-capacitance properties of the oil deposit model unchanged.

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Xia, Yongfang, Tingyong Fang, Haitao Wang, Erbao Guo et Jinwei Ma. « Numerical investigation of low-velocity filtration combustion instability based on the initial preheating non-uniformity ». E3S Web of Conferences 136 (2019) : 02040. http://dx.doi.org/10.1051/e3sconf/201913602040.

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The effects of the initial preheating perturbation on the dynamical behaviors of FGC wave propagation instability for low-velocity FGC in packed bed are studied numerically. The behaviors of the flame front inclination, break, and shrinking instabilities are always observed in experiments. Based on the experimental phenomena, an initial thermal perturbation model is numerically proposed as to predict the deformation behaviors of the flame front instabilities. The typical flame shapes are obtained depending on filtration velocity, equivalence ratio, and initial preheating temperature difference. It is demonstrated that the development of flame front inclination instability is proportional to the magnitude of initial preheating perturbation. At a lower equivalence ratio, the initial thermal perturbation of 300 K leads to the evolution of flame front break. Increasing filtration velocity leads to the appearance of flame front break, due to the intensification of the hydrodynamic instability. In addition, a perculiar instability of flame front shifting is also confirmed with the initial thermal perturbation of 400 K, which results in a fuel leakage of incomplete combustion.

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Jepsen, Kasper L., Mads V. Bram, Leif Hansen, Zhenyu Yang et Steven M. Ø. Lauridsen. « Online Backwash Optimization of Membrane Filtration for Produced Water Treatment ». Membranes 9, n^o 6 (5 juin 2019) : 68. http://dx.doi.org/10.3390/membranes9060068.

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In the offshore oil and gas sector, produced water is discharged into the sea, but increasing environmental concerns and stricter governmental regulations require new technologies to be considered. Membrane filtration is a promising technology to improve separation, but fouling of the membranes causes a significant reduction in flow capacity. To reduce fouling, optimization of the backwashing parameters is given much attention. Comprehensive and time-consuming experiments are used to model the effect of backwashing, but most methods neglect time varying features present in the offshore produced water treatment train. In this paper, a backwashing scheduling algorithm is proposed, which dynamically selects the filtration and backwashing durations to maximize the average net permeate production. The proposed algorithm is tested on a lab-scaled pilot plant, where it was able to adapt as irreversible fouling accumulated and the OiW concentration changed. The paper concludes that the removal rate of oil fouling was observed to be dependent on the rate at which the backwashing pressure could be established. As the proposed method online adapts to the current conditions, it can improve the filtration capacity compared to cases with constant backwashing and filtration durations throughout the lifetime of the facilities.

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Zhang, Shu Dong, Zhen Xing Sun et Ning Luo. « Design and Implementation of Report Model for Base Information of Farm Produce Quantity Security Based on TelerikReporting Component ». Key Engineering Materials 480-481 (juin 2011) : 872–76. http://dx.doi.org/10.4028/www.scientific.net/kem.480-481.872.

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We design and implement a kind of dynamic report model in Silverlight application which based on TelerikReporting component and the technology of dynamic linked library. This model supports multi-parameter choice and can format custom report dynamically based on decided condition. By custom filter, this model implements filtrating large amount of data by receiving multiple parameters with multiple values.

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Grudzien, Colin, Alberto Carrassi et Marc Bocquet. « Chaotic dynamics and the role of covariance inflation for reduced rank Kalman filters with model error ». Nonlinear Processes in Geophysics 25, n^o 3 (4 septembre 2018) : 633–48. http://dx.doi.org/10.5194/npg-25-633-2018.

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Abstract. The ensemble Kalman filter and its variants have shown to be robust for data assimilation in high dimensional geophysical models, with localization, using ensembles of extremely small size relative to the model dimension. However, a reduced rank representation of the estimated covariance leaves a large dimensional complementary subspace unfiltered. Utilizing the dynamical properties of the filtration for the backward Lyapunov vectors, this paper explores a previously unexplained mechanism, providing a novel theoretical interpretation for the role of covariance inflation in ensemble-based Kalman filters. Our derivation of the forecast error evolution describes the dynamic upwelling of the unfiltered error from outside of the span of the anomalies into the filtered subspace. Analytical results for linear systems explicitly describe the mechanism for the upwelling, and the associated recursive Riccati equation for the forecast error, while nonlinear approximations are explored numerically.

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CORNEA, O., K. A. DE REZENDE et M. R. DA SILVEIRA. « Spectral sequences in Conley’s theory ». Ergodic Theory and Dynamical Systems 30, n^o 4 (13 octobre 2009) : 1009–54. http://dx.doi.org/10.1017/s0143385709000479.

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AbstractIn this paper, we analyse the dynamics encoded in the spectral sequence (Er,dr) associated with certain Conley theory connection maps in the presence of an ‘action’ type filtration. More specifically, we present an algorithm for finding a chain complex C and its differential; the method uses a connection matrix Δ to provide a system that spans Er in terms of the original basis of C and to identify all of the differentials drp:Erp→Erp−r. In exploring the dynamical implications of a non-zero differential, we prove the existence of a path that joins the singularities generating E0p and E0p−r in the case where a direct connection by a flow line does not exist. This path is made up of juxtaposed orbits of the flow and of the reverse flow, and proves to be important in some applications.

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Kong, Xiangwei, Bing Liu, Hongxing Xu, Jianwen Shen et Song Li. « Optimization and Performance Evaluation of Foam Acid Systems for Plugging Removal in Low Pressure Oil and Gas Reservoirs ». Processes 11, n^o 3 (21 février 2023) : 649. http://dx.doi.org/10.3390/pr11030649.

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Foam acidization has unique advantages such as low damage, low filtration, low friction, high efficiency, excellent retardation, and fast liquid discharge rate, which is suitable for stimulation and reconstruction of low-pressure oil and gas reservoirs that have been developed over many years. It is obtained that the main chemical components of downhole plugging materials include vegetable oil, fatty acids and their esters, silicone oil, amide polymers, and additional organic components, as well as non-organic components, elemental sulfur, ferrous sulfide, iron disulfide, silicon dioxide, mineral salts, etc. The performance of foam acid was investigated by experiments, including the effective range of action of active acids, reducing filtration, increasing temperature resistance and high-temperature stability of foam acid deep wells. The new foam acid system is developed and optimized to suitable for low-pressure deep well acidification operations. Experimental evaluation optimized the acid foaming agent and foam stabilizer and developed a new foam acid formulation with foam stability, filter loss reduction, temperature resistance, and easy backflow performance. The experimental condition is that the temperature is 90 °C, the foam quality can reach more than 70% when mixed for more than 30 s, the average half-life is 38.75 min, and the liquid separation rate is 19.90 s/mL. Its suspension is better than that of conventional hydrochloric acid, its corrosion rate is 1.872 g/m2·h, and the flowback rate of foam acid residue reaches 97%. Experimental evaluation has shown that the developed foam acid features high surface activity, stable foam, strong temperature resistance, significant speed and corrosion suppression, and excellent drainage assist performance. Dynamical simulation evaluation of reservoir core foam acidification demonstrated that the foam features long-life, strong suspension capacity, excellent rheology, low filtration, and significant acidization and plug removal effects, and can be used in stimulating the medium-deep, high-temperature, and low-pressure oil and gas reservoirs.

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Abdelraouf, M. E., A. Kandil, W. K. Zahra et A. Elsaid. « Investigation of a MEMS resonator model with quintic nonlinearity ». Journal of Physics : Conference Series 2793, n^o 1 (1 juillet 2024) : 012019. http://dx.doi.org/10.1088/1742-6596/2793/1/012019.

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Abstract Micro-electromechanical system (MEMS) resonator is decidedly utilized in a diversity of areas, including time referencing, movement sensing, signal filtration, mass detecting, and further numerous applications. The aim of this article is to use the multiple scales approach to derive analytical formulas for MEMS resonator vibration response. The properties of the complicated nonlinear system at various AC and DC voltages are investigated to be extremely well captured by modeling the dynamics of the micro-beam using multiple scales technique. The resulting Jacobian matrix eigenvalues are tested to verify the stability ranges of these solutions; hence, the jump phenomenon that occurs in experimental performance is interpreted. To study the influence of resonator characteristics on the nonlinear dynamical behavior of such a beam, several response plots are presented. Finally, a numerical solution is obtained with the fourth order Rung-Kutta method to verify the studied model’s overall behavior.

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Liu, Xu. « Optimization of sewage treatment processes : Process control based on artificial intelligence ». Applied and Computational Engineering 93, n^o 1 (8 novembre 2024) : 185–90. http://dx.doi.org/10.54254/2755-2721/93/20240981.

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Abstract. The optimization of sewage treatment processes is critical for improving efficiency and reducing energy consumption. This paper explores the application of machine learning and artificial intelligence algorithms in optimizing key processes such as aeration, sedimentation, and filtration. By leveraging real-time monitoring and adaptive control, these algorithms can dynamically adjust operational parameters to enhance treatment efficiency and minimize energy usage. This study provides detailed insights into the implementation and benefits of AI-driven process control in sewage treatment, supported by case studies and data analysis. The findings indicate significant improvements in treatment performance, showcasing the transformative potential of AI in environmental engineering.

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Legowo, Ari, Zahratu H. Mohamad et Hoon Cheol Park. « Mixed Unscented Kalman Filter and Differential Evolution for Parameter Identification ». Applied Mechanics and Materials 256-259 (décembre 2012) : 2347–53. http://dx.doi.org/10.4028/www.scientific.net/amm.256-259.2347.

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This paper presents parameters estimation techniques for coupled industrial tanks using the mixed Unscented Kalman Filter (UKF) and Differential Evolution (DE) method. UKF have known to be a typical estimation technique used to estimate the state vectors and parameters of nonlinear dynamical systems and DE is one of the most powerful stochastic real-parameter optimization algorithms. Meanwhile, liquid tank systems play important role in industrial application such as in food processing, beverage, dairy, filtration, effluent treatment, pharmaceutical industry, water purification system, industrial chemical processing and spray coating. The aim is to model the coupled tank system using mixed UKF and DE method to estimate the parameters of the tank. First, a non-linear mathematical model is developed. Next, its parameters are identified using mixed Unscented Kalman Filter (UKF) and Differential Evolution (DE) based on the experimental data. DE algorithm is integrated into the UKF algorithm to optimize the Kalman gain obtained. The obtained results demonstrate good performances.

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Shakhverdiev, A. Kh. « Effect of irreversible and unstable processes on reservoir recovery ». SOCAR Proceedings, n^o 1 (30 mars 2024) : 87–94. http://dx.doi.org/10.5510/ogp20240100945.

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Hysteresis behaviour, during filtration, is caused by lithological differences in geo-fluid-dynamical media, geological-physical characteristics, and properties of saturating fluids. Typically, irreversible changes are caused by excessive external loads on the investigated porous media. The proposed solutions are part of a new concept of unsteady water flooding, which allows for early prediction of water breakthrough into production wells. This text discusses the negative impact of hysteresis phenomena on oil recovery and proposes a solution. To solve this task, control parameters, based on growth models and catastrophe theory, are selected so to predict local instability and irreversibility before the bifurcation moment., Herewith it is necessary to develop technologies, which can prevent irreversible changes in permeability, capillary retention of oil, oil degassing, and to consider the unstable behavior of the displacement front. Systemic optimization of oil field development aims to increase oil production, effectively mobilize, save injected and recovered water and gas. Keywords: hysteresis; instability; irreversible changes in permeability and porosity; phase transition; capillary forces; oil recovery.

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Holdich, R. G., et J. S. Boston. « Microfiltration using a dynamically formed membrane ». Filtration & ; Separation 27, n^o 3 (mai 1990) : 184–87. http://dx.doi.org/10.1016/0015-1882(90)80061-o.

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González, Enrique, Oliver Díaz, Luisa Vera, Luis E. Rodríguez-Gómez et Juan Rodríguez-Sevilla. « Feedback control system for filtration optimisation based on a simple fouling model dynamically applied to membrane bioreactors ». Journal of Membrane Science 552 (avril 2018) : 243–52. http://dx.doi.org/10.1016/j.memsci.2018.02.007.

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Garg, Puneet. « A Review of Podocyte Biology ». American Journal of Nephrology 47, Suppl. 1 (2018) : 3–13. http://dx.doi.org/10.1159/000481633.

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Background: Podocyte biology is a developing science that promises to help improve understanding of the mechanistic nature of multiple diseases associated with proteinuria. Proteinuria in nephrotic syndrome has been linked to mechanistic dysfunctions in the renal glomerulus involving the function of podocyte epithelial cells, including podocyte foot process effacement. Summary: Developments in imaging technology are improving knowledge of the detailed structure of the human renal glomerulus and cortex. Podocyte foot processes attach themselves to the glomerular capillaries at the glomerular basement membrane (GBM) forming intercellular junctions that form slit diaphragm filtration barriers that help maintain normal renal function. Damage in this area has been implicated in glomerular disease. Injured podocytes undergo effacement whereby they lose their structure and spread out, leading to a reduction in filtration barrier function. Effacement is typically associated with the presence of proteinuria in focal segmental glomerulosclerosis, minimal change disease, and diabetes. It is thought to be due to a breakdown in the actin cytoskeleton of the foot processes, complex contractile apparatuses that allow podocytes to dynamically reorganize according to changes in filtration requirements. The process of podocyte depletion correlates with the development of glomerular sclerosis and chronic kidney disease. Focal adhesion complexes that interact with the underlying GBM bind the podocytes within the glomerular structure and prevent their detachment. Key Messages: Knowledge of glomerular podocyte biology is helping to advance our understanding of the science and mechanics of the glomerular filtering process, opening the way to a variety of new potential applications for clinical targeting.

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Nikiforov, Anatoly, et Roman Sadovnikov. « Particle removal by two-phase filtration flow from a porous medium under wave action ». Georesursy 23, n^o 4 (30 novembre 2021) : 58–64. http://dx.doi.org/10.18599/grs.2021.4.7.

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The paper discusses the influence of wave action on the process of detachment and removal of particles from a porous body by a two-phase filtration flow. When modeling this process, the problem of the influence of the wave field on the force under the action of which the particles are detached from the pore walls is solved. For the first time, a pore-size distribution function is used for its solution. An expression for the critical flow velocity under wave action has been obtained. Critical frequency value of wave action depends on the capillary radius and the smaller the capillary radius is, the higher frequency is needed to enhance the effect of the action. At higher frequency of oscillation the peak of maximum change in the thickness of the sedimentary layer is shifted towards the pores of small radius. To maintain the influence of the wave field on the filtration parameters of the porous medium, the wave action should be carried out at a dynamically changing frequency range to increase the coverage of the effect of as many pores as possible. It is shown that particle removal during wave action increases due to the action of inertial forces, which reduce the influence of forces holding the particles on the pore surface.

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Schmid, Martin G., Karin Schreiner, Daniela Reisinger et Gerald Gübitz. « Fast chiral separation by ligand-exchange HPLC using a dynamically coated monolithic column ». Journal of Separation Science 29, n^o 10 (juillet 2006) : 1470–75. http://dx.doi.org/10.1002/jssc.200600102.

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Anzian, Kouadio Fabrice, Mykhailo Illich Fyk, Al-Sultan Mohammed Bassam, Mohammed Khaleel Abbood, Haval Mohammed Abdullatif et Yevhen Alexender Shapchenko. « Analysis of Dynamical Heat Conductivity of the Reservoir and Fluid Evacuation Zone on the Gas Condensate Well Flow Rate ». J — Multidisciplinary Scientific Journal 3, n^o 1 (14 mars 2020) : 124–37. http://dx.doi.org/10.3390/j3010011.

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This study shows that the thermal conductivity of the rock borehole adjacent to the wells varies depending on the operation of the well. This is due to the fact that the actual temperature and temperature difference affect the humidity and other thermal properties of the rocks, which in turn affect the heat transfer coefficient across the section between the moving gas and the rocks. The static temperature field of primitive geothermal gradients acquires changes in a dynamic form. Theoretical consideration of changes in the thermal conductivity of rocks near the face and the wells is proposed to improve the prediction of gas condensate wells production. The result is achieved by introducing the specified equations of the thermal energy balance in the radial filtration and lifting of well products, which contain the coefficients of heat exchange and throttling. The refinement bias estimation of the 10%–15% level of gas condensate well extraction is shown using proposed methodological approach to relatively well-known (traditional in the field development practice) methods for estimating the extraction of a “medium well” from a particular oil and gas field evaluation. The results of this work demonstrate important scientific, applied, educational and methodological significance of using the methodology presented by the authors.

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Virbulis, J., J. Telicko, A. Sabanskis, D. D. Vidulejs et A. Jakovics. « Numerical Model and System for Prediction and Reduction of Indoor Infection Risk ». Latvian Journal of Physics and Technical Sciences 60, s6 (1 décembre 2023) : 5–19. http://dx.doi.org/10.2478/lpts-2023-0041.

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Abstract The developed numerical model assesses the risk of a COVID-19 infection in a room based on the measurements of temperature, relative humidity, CO2 and particle concentration, as well as the number of people and occurrences of speech, coughing, and sneezing obtained through a low-cost sensor system. As the model operates faster than real-time, it can dynamically inform the persons in the room or building management system about the predicted risk level. When the infection risk is high, the model can activate an air purifier equipped with filtration and UV-C disinfection. This solution improves energy efficiency by reducing the ventilation intensity required during colder seasons to maintain the same safety level and activating the purifier only when the predicted infection risk surpasses a specified threshold.

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Sanders, Steven L., Krassimira A. Garbett et P. Anthony Weil. « Molecular Characterization of Saccharomyces cerevisiae TFIID ». Molecular and Cellular Biology 22, n^o 16 (15 août 2002) : 6000–6013. http://dx.doi.org/10.1128/mcb.22.16.6000-6013.2002.

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ABSTRACT We previously defined Saccharomyces cerevisiae TFIID as a 15-subunit complex comprised of the TATA binding protein (TBP) and 14 distinct TBP-associated factors (TAFs). In this report we give a detailed biochemical characterization of this general transcription factor. We have shown that yeast TFIID efficiently mediates both basal and activator-dependent transcription in vitro and displays TATA box binding activity that is functionally distinct from that of TBP. Analyses of the stoichiometry of TFIID subunits indicated that several TAFs are present at more than 1 copy per TFIID complex. This conclusion was further supported by coimmunoprecipitation experiments with a systematic family of (pseudo)diploid yeast strains that expressed epitope-tagged and untagged alleles of the genes encoding TFIID subunits. Based on these data, we calculated a native molecular mass for monomeric TFIID. Purified TFIID behaved in a fashion consistent with this calculated molecular mass in both gel filtration and rate-zonal sedimentation experiments. Quite surprisingly, although the TAF subunits of TFIID cofractionated as a single complex, TBP did not comigrate with the TAFs during either gel filtration chromatography or rate-zonal sedimentation, suggesting that TBP has the ability to dynamically associate with the TFIID TAFs. The results of direct biochemical exchange experiments confirmed this hypothesis. Together, our results represent a concise molecular characterization of the general transcription factor TFIID from S. cerevisiae.

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Shi, Ruheng, Yuanlong Zhang, Tiankuang Zhou et Lingjie Kong. « HiLo Based Line Scanning Temporal Focusing Microscopy for High-Speed, Deep Tissue Imaging ». Membranes 11, n^o 8 (17 août 2021) : 634. http://dx.doi.org/10.3390/membranes11080634.

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High-speed, optical-sectioning imaging is highly desired in biomedical studies, as most bio-structures and bio-dynamics are in three-dimensions. Compared to point-scanning techniques, line scanning temporal focusing microscopy (LSTFM) is a promising method that can achieve high temporal resolution while maintaining a deep penetration depth. However, the contrast and axial confinement would still be deteriorated in scattering tissue imaging. Here, we propose a HiLo-based LSTFM, utilizing structured illumination to inhibit the fluorescence background and, thus, enhance the image contrast and axial confinement in deep imaging. We demonstrate the superiority of our method by performing volumetric imaging of neurons and dynamical imaging of microglia in mouse brains in vivo.

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Schiller, Alicia M., Peter R. Pellegrino et Irving H. Zucker. « Renal nerves dynamically regulate renal blood flow in conscious, healthy rabbits ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 310, n^o 2 (15 janvier 2016) : R156—R166. http://dx.doi.org/10.1152/ajpregu.00147.2015.

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Despite significant clinical interest in renal denervation as a therapy, the role of the renal nerves in the physiological regulation of renal blood flow (RBF) remains debated. We hypothesized that the renal nerves physiologically regulate beat-to-beat RBF variability (RBFV). This was tested in chronically instrumented, healthy rabbits that underwent either bilateral surgical renal denervation (DDNx) or a sham denervation procedure (INV). Artifact-free segments of RBF and arterial pressure (AP) from calmly resting, conscious rabbits were used to extract RBFV and AP variability for time-domain, frequency-domain, and nonlinear analysis. Whereas steady-state measures of RBF, AP, and heart rate did not statistically differ between groups, DDNx rabbits had greater RBFV than INV rabbits. AP-RBF transfer function analysis showed greater admittance gain in DDNx rabbits than in INV rabbits, particularly in the low-frequency (LF) range where systemic sympathetic vasomotion gives rise to AP oscillations. In the LF range, INV rabbits exhibited a negative AP-RBF phase shift and low coherence, consistent with the presence of an active control system. Neither of these features were present in the LF range of DDNx rabbits, which showed no phase shift and high coherence, consistent with a passive, Ohm's law pressure-flow relationship. Renal denervation did not significantly affect nonlinear RBFV measures of chaos, self-affinity, or complexity, nor did it significantly affect glomerular filtration rate or extracellular fluid volume. Cumulatively, these data suggest that the renal nerves mediate LF renal sympathetic vasomotion, which buffers RBF from LF AP oscillations in conscious, healthy rabbits.

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Werner, Roman Alejandro, Alexander Michael Hummel, Dominik Ulrich Geier et Thomas Becker. « Investigations on Backflush Cleaning of Spent Grain-Contaminated Filter Cloths Using Continuous and Pulsed Jets ». Foods 11, n^o 12 (15 juin 2022) : 1757. http://dx.doi.org/10.3390/foods11121757.

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This study investigated the continuous and pulsed backflush cleaning of woven fabrics that act as filter media in the food and beverage industry. Especially in breweries, they are commonly used in mash filters to separate solid spent grains from liquid wort. After filtration, the removal of such cereal residues via self-discharge is necessary. However, this filter cake discharge is typically incomplete, and various spots remain contaminated. In addition to the reduced filter performance of subsequent batches, cross-contamination risk increases significantly. A reproducible contamination method focusing on the use case of a mash filter was developed for this study. Additionally, a residue analysis based on microscopical image processing helped to assess cleaning efficiency. The experimental part compared two backflushing procedures for mash filters and demonstrated fluid dynamical, procedural, and economic differences in cleaning. Specifically, pulsed jets show higher efficiency in reaching cleanliness faster, with fewer cleaning agents and less time. According to the experimental results, the fluid flow conditions depended highly on cloth geometry and mesh sizes. Larger mesh sizes significantly favored the cloth’s cleanability as a larger backflush volume can reach contamination. With these results, cloth cleaning can be improved, enabling the realization of demand-oriented cleaning concepts.

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Matcharashvili, T., T. Chelidze et Z. Javakhishvili. « Nonlinear analysis of magnitude and interevent time interval sequences for earthquakes of the Caucasian region ». Nonlinear Processes in Geophysics 7, n^o 1/2 (30 juin 2000) : 9–20. http://dx.doi.org/10.5194/npg-7-9-2000.

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Abstract. It is well known that lithospheric seismic processes are characterized by self-similarity or scale invariance in terms of earthquake-size, time, space and space-time distributions, although precise details of underlying dynamics are not clear. In this study we apply nonlinear dynamics theory tools, such as a correlation dimension, "surrogate" data analysis and positive Lyapunov exponent calculation, to investigate dynamical characteristics of seismicity in the Caucasian region. Interevent time intervals and magnitude sequences are considered for different area and magnitude windows. We find significant evidence of a low dimensional nonlinear structure of earthquake time distribution, obtained by consideration of time interval sequences between all events encountered, above some threshold magnitude, in the original catalogue. However nonlinear structure is absent in artificially generated sequences of time intervals between independent events as well as time intervals between aftershocks. It seems that this kind of filtration of the original catalogue destroys the existing temporal structure of considered lithospheric processes. Unlike artificial inter-aftershock time interval sequences, obtained by removing independent events from the original series, the time interval sequence between the Racha earthquake aftershocks reveals clear evidence of nonlinear structure. Earthquake magnitude dynamics. for all considered regions and magnitude windows, reveal high dimensional nonlinearity.

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He, Yan, Colleen Isele, Weiying Hou et Margaret Ruesch. « Rapid analysis of charge variants of monoclonal antibodies with capillary zone electrophoresis in dynamically coated fused-silica capillary ». Journal of Separation Science 34, n^o 5 (25 janvier 2011) : 548–55. http://dx.doi.org/10.1002/jssc.201000719.

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Chie, Lee Hooi, Ahmad Khairi Abd Wahab et Fauzan Kamal Mohd Yapandi. « Development of the Long-Term Morphodynamic Model to Determine the Seawater Intake Location ». MATEC Web of Conferences 203 (2018) : 01004. http://dx.doi.org/10.1051/matecconf/201820301004.

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Seawater intake structures are often used at coastal power plant to draw ambient seawater into the cooling system for operation. However, improper selection of water intake location will lead to sediments deposition at the intake structure causing lower intake flow rate, clogging of water filtration devices and reduces the efficiency of the power plant. A 2D process-based model is developed to investigate the morphodynamic behavior of the Kapar coast. The model is developed by coupling the processes of hydrodynamic, waves and sediment transport. The processes are interacted dynamically with bathymetry and lead to the morphological changes. The model is input with the schematisation of seasonal wind-wave conditions and a representative morphological tide. Morphological acceleration technique is used to simulate the long-term morphodynamic changes with acceptable computational times. Sedimentation and erosion patterns are represented by the model and suitable intake location is determined based on the long-term morphodynamic investigation.

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Ferreira, Mónica P. S., Afonso S. Gonçalves, Joana C. Antunes, João Bessa, Fernando Cunha et Raúl Fangueiro. « Fibrous Structures : An Overview of Their Responsiveness to External Stimuli towards Intended Application ». Polymers 16, n^o 10 (9 mai 2024) : 1345. http://dx.doi.org/10.3390/polym16101345.

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In recent decades, the interest in responsive fibrous structures has surged, propelling them into diverse applications: from wearable textiles that adapt to their surroundings, to filtration membranes dynamically altering selectivity, these structures showcase remarkable versatility. Various stimuli, including temperature, light, pH, electricity, and chemical compounds, can serve as triggers to unleash physical or chemical changes in response. Processing methodologies such as weaving or knitting using responsive yarns, electrospinning, as well as coating procedures, enable the integration of responsive materials into fibrous structures. They can respond to these stimuli, and comprise shape memory materials, temperature-responsive polymers, chromic materials, phase change materials, photothermal materials, among others. The resulting effects can manifest in a variety of ways, from pore adjustments and altered permeability to shape changing, color changing, and thermal regulation. This review aims to explore the realm of fibrous structures, delving into their responsiveness to external stimuli, with a focus on temperature, light, and pH.

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Dong, Jianghu(James), Shijia Wang, Liangliang Wang, Jagbir Gill et Jiguo Cao. « Joint modelling for organ transplantation outcomes for patients with diabetes and the end-stage renal disease ». Statistical Methods in Medical Research 28, n^o 9 (19 juillet 2018) : 2724–37. http://dx.doi.org/10.1177/0962280218786980.

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This article is motivated by jointly modelling longitudinal and time-to-event clinical data of patients with diabetes and end-stage renal disease. All patients are on the waiting list for the pancreas transplant after kidney transplant, and some of them have a pancreas transplant before kidney transplant failure or death. Scant literature has studied the dynamical joint relationship of the estimated glomerular filtration rates trajectory, the effect of pancreas transplant, and time-to-event outcomes, although it remains an important clinical question. In an attempt to describe the association in the multiple outcomes, we propose a new joint model with a longitudinal submodel and an accelerated failure time submodel, which are linked by some latent variables. The accelerated failure time submodel is used to determine the relationship of the time-to-event outcome with all predictors. In addition, the piecewise linear function in the survival submodel is used to calculate the dynamic hazard ratio curve of a time-dependent side event, because the effect of the side event on the time-to-event outcome is non-proportional. The model parameters are estimated with a Monte Carlo EM algorithm. The finite sample performance of the proposed method is investigated in simulation studies. Our method is demonstrated by fitting the joint model for the clinical data of 13,635 patients with diabetes and the end-stage renal disease.

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Akamatsu, Kazuki, Miyuki Okuyama, Keita Mitsumori, Akihiro Yoshino, Aiko Nakao et Shin-ichi Nakao. « Effect of the composition of the copolymer of carboxybetaine and n-butylmethacrylate on low-fouling property of dynamically formed membrane ». Separation and Purification Technology 118 (octobre 2013) : 463–69. http://dx.doi.org/10.1016/j.seppur.2013.07.034.

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Sverrisson, Kristinn, Josefin Axelsson, Anna Rippe, Daniel Asgeirsson et Bengt Rippe. « Dynamic, size-selective effects of protamine sulfate and hyaluronidase on the rat glomerular filtration barrier in vivo ». American Journal of Physiology-Renal Physiology 307, n^o 10 (15 novembre 2014) : F1136—F1143. http://dx.doi.org/10.1152/ajprenal.00181.2014.

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The proteinuric actions of protamine sulfate (PS) have classically been, at least partly, attributed to alterations of the negatively charged glomerular endothelial glycocalyx. To investigate whether the charge-selective properties of the glomerular filtration barrier (GFB) would be altered by PS, we assessed the glomerular sieving of conventional, uncharged, polydispersed Ficoll (n-Ficoll) compared with charge modified, conformationally intact, anionic (carboxymethylated) Ficoll (a-Ficoll) before and after systemic infusions of PS in rats. For comparison, we also investigated the impact of hyaluronidase (hyase), which partially degrades the glycocalyx, on GFB permeability. In anaesthetized Wistar rats, blood access was achieved, and the left ureter was cannulated for urine collection. Rats were infused with either n-Ficoll or a-Ficoll before and during systemic infusions with either PS or hyase. Plasma and urine samples were taken repeatedly and analyzed by high-performance size exclusion chromatography to assess glomerular sieving coefficients (θ) for Ficoll (radius 10–80 Å). The GFB showed a significant glomerular charge selectivity for Ficoll molecules of radius 20–35 Å. PS and hyase infusions reversibly increased θ for large Ficoll molecules (Ficoll molecules of radius 50–80 Å). Thus, for PS, θ for a-Ficoll molecules of radius 70 Å increased from 2.47 × 10−5± 1.1−5to 7.25 × 10−5± 1.1−5( P < 0.05) at 15 min. For hyase, changes in a-Ficoll molecules of radius 50–80 Å were, however, not statistically significant. Neither PS nor hyase had any effect on θ for n-Ficoll molecules of radius 20–45 Å or a-Ficoll molecules of radius 20–45 Å. It is concluded that systemically administered PS and hyase in moderate doses dynamically decreased the size selectivity of the rat GFB without affecting its charge selective properties.

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Yu, Bing, Hailin Cong, Huwei Liu, Yuanzong Li et Feng Liu. « Ionene-dynamically coated capillary for analysis of urinary and recombinant human erythropoietin by capillary electrophoresis and online electrospray ionization mass spectrometry ». Journal of Separation Science 28, n^o 17 (novembre 2005) : 2390–400. http://dx.doi.org/10.1002/jssc.200500156.

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Khasambiev, Mokhammad Vakhaevich. « Boundary value problemfor multidimensional fractional advection-dispersion equation ». Vestnik MGSU, n^o 5 (mai 2015) : 35–43. http://dx.doi.org/10.22227/1997-0935.2015.5.35-43.

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In recent time there is a very great interest in the study of differential equations of fractional order, in which the unknown function is under the symbol of fractional derivative. It is due to the development of the theory of fractional integro-differential theory and application of it in different fields.The fractional integrals and derivatives of fractional integro-differential equations are widely used in modern investigations of theoretical physics, mechanics, and applied mathematics. The fractional calculus is a very powerful tool for describing physical systems, which have a memory and are non-local. Many processes in complex systems have nonlocality and long-time memory. Fractional integral operators and fractional differential operators allow describing some of these properties. The use of the fractional calculus will be helpful for obtaining the dynamical models, in which integro-differential operators describe power long-time memory by time and coordinates, and three-dimensional nonlocality for complex medium and processes.Differential equations of fractional order appear when we use fractal conception in physics of the condensed medium. The transfer, described by the operator with fractional derivatives at a long distance from the sources, leads to other behavior of relatively small concentrations as compared with classic diffusion. This fact redefines the existing ideas about safety, based on the ideas on exponential velocity of damping. Fractional calculus in the fractal theory and the systems with memory have the same importance as the classic analysis in mechanics of continuous medium.In recent years, the application of fractional derivatives for describing and studying the physical processes of stochastic transfer is very popular too. Many problems of filtration of liquids in fractal (high porous) medium lead to the need to study boundary value problems for partial differential equations in fractional order.In this paper the authors first considered the boundary value problem for stationary equation for mass transfer in super-diffusion conditions and abnormal advection. Then the solution of the problem is explicitly given. The solution is obtained by the Fourier’s method.The obtained results will be useful in liquid filtration theory in fractal medium and for modeling the temperature variations in the heated bar.

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Remelli, Maurizio, Giovanni Pozzati et Chiara Conato. « Direct chiral resolution of underivatized amino acids on a stationary phase dynamically modified with the ion-exchanger N τ -decyl-l -spinacine ». Journal of Separation Science 38, n^o 6 (5 février 2015) : 894–900. http://dx.doi.org/10.1002/jssc.201401381.

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Patel, Darshil, Rushali Dargan, Wesley S. Burr, Benoit Daoust et Shari Forbes. « Identifying the Early Post-Mortem VOC Profile from Cadavers in a Morgue Environment Using Comprehensive Two-Dimensional Gas Chromatography ». Separations 10, n^o 11 (10 novembre 2023) : 566. http://dx.doi.org/10.3390/separations10110566.

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Understanding the VOC profile released during the early post-mortem period is essential for applications in training human remains detection dogs and urban search and rescue operations (USAR) to rapidly locate living and deceased victims. Human cadavers were sampled at the UQTR morgue within a 0–72 h post-mortem interval. VOC samples were collected from the headspace above the cadavers, using Tenax TA/Carbograph 5TD dual sorbent tubes, and analyzed using GC×GC-TOFMS. Multiple data processing steps, including peak table alignment and filtering, were undertaken using LECO ChromaToF and custom scripts in R programming language. This study identified 104 prevalent VOCs, some of which are linked to human decomposition, while others are connected to the persistence of living scent. Principal Component Analysis (PCA) further highlighted that VOC profiles can change dynamically over time, even in a controlled setting. The findings underscore the complexity and variability in VOC profiles during the early post-mortem period. This variability is influenced by multiple factors including the individual’s biological and physiological conditions. Despite the challenges in characterizing these profiles, the identified VOCs could potentially serve as markers in forensic applications. The study also highlights the need for additional research to build a dataset of VOCs for more robust forensic applications.

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