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3rd Theoretical Fluid Mechanics Meeting 2002

作者： Borggaard, Jeff Burns, John Interdisciplinary Center for Applied Mathematics Department of Mathematicsm Virginia Tech Blacksburg VA 24061 United States

ISBN: (纸本)9781624101168

In this paper, we pose an optimal design problem involving a feedback control system. The location of the actuator is the design parameter of interest. Since feedback control problems need to be solved efficiently when eventually cascaded with an optimization algorithm, we emphasize two features of distributed parameter control problems that need to be utilized when computing feedback control gains: sparsity and low dimensional control inputs and out-puts. © 2002 by the author(s).

关键词： Feedback control

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Block ratio optimized cationic polyacrylamides for enhanced nitrate rejection under applied potential

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Chemical Engineering Journal 2025年 513卷

作者： Vahid, Hossein Hashemi, Arsalan Khavani, Mohammad Sharma, Abhinav Mofrad, Mohammad R.K. Ala-Nissila, Tapio Leibniz-Institut für Polymerforschung Dresden Institut Theorie der Polymere Dresden01069 Germany Department of Applied Physics Aalto University P.O. Box 15600 AaltoFI-00076 Finland Molecular Cell Biomechanics Laboratory Departments of Bioengineering and Mechanical Engineering University of California Berkeley BerkeleyCA United States Faculty of Mathematics Natural Sciences and Materials Engineering: Institute of Physics University of Augsburg Universitätsstraße 1 Augsburg86159 Germany Molecular Biophysics and Integrative Bioimaging Division Lawrence Berkeley National Laboratory BerkeleyCA United States Quantum Technology Finland Center of Excellence Department of Applied Physics Aalto University P.O. Box 15600 AaltoFI-00076 Finland Interdisciplinary Centre for Mathematical Modelling and Department of Mathematical Sciences Loughborough University Loughborough LeicestershireLE11 3TU United Kingdom

Nitrate contamination in water sources is a growing environmental concern, threatening both human health and ecosystems. However, its combination with sodium forms NaNO3, a compound essential for various industrial applications. The integration of charged polymers and reverse osmosis (RO) membranes presents a promising approach to capture undesired ions and enhance water purification efficiency. In this paper, di-block cationic polyacrylamides (DCPAMs) as charged polymers are evaluated separately in bulk solution and in combination with the RO process to capture nitrite ions introduced by NaNO3. Molecular dynamics simulations are conducted to systematically investigate the effects of polymer block ratio and concentration, as well as salt concentration, on NO3− capturing. Our results in bulk solution indicate that an optimal block ratio of 8:12 yields the highest performance, with polymers adopting a stretched conformation. When an electric potential is applied, anions are strongly attracted to the positively charged electrode, and nitrate ions remain closer to the electrode surface than other ions. Our findings reveal that a 12:8 ratio outperforms all other ratios. The simultaneous application of RO membranes and DCPAMs achieves salt rejection efficiencies ranging from 78% to 100%, depending on DCPAM type and salt concentration. These findings pave the way for further computational studies on combined processes to advance water purification technologies. © 2025 The Authors

关键词： Molecular dynamics

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Effective bifurcation analysis: a time-stepper-based approach (vol 15, pg 491, 2002)

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NONLINEARITY 2002年第3期15卷 955-955页

作者： Runborg, O Theodoropoulos, C Kevrekidis, IG Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 USA Department of Chemical Engineering Princeton University Princeton NJ 08544 USA

We introduce a numerical approach to perform the effective (coarse-scale) bifurcation analysis of solutions of dissipative evolution equations with spatially varying coefficients. The advantage of this approach is that the `coarse model' (the averaged, effective equation) need not be explicitly constructed. The method only uses a time-integrator code for the detailed problem and judicious choices of initial data and integration times; the bifurcation computations are based on the so-called recursive projection method (Shroff and Keller 1993 SIAM J. Numer. Anal. 30 1099-120).

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An Attempt at Axiomatization of Extending Mechanism of Solutions to the Fluid Dynamical Systems

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Chinese Annals of mathematics,Series B 2024年第6期45卷 957-970页

作者： Jinkai LI Meng WANG Wendong WANG South China Research Center for Applied Mathematics and Interdisciplinary Studies School of Mathematical SciencesSouth China Normal UniversityGuangzhou 510631China Department of Mathematics Zhejiang UniversityHangzhou 310027China School of Mathematical Sciences Dalian University of TechnologyDalian 116024LiaoningChina

Note that some classic fluid dynamical systems such as the Navier-Stokes equations, Magnetohydrodynamics (MHD for short), Boussinesq equations and etc., are observably different from each other but obey some energy inequalities of the similar *** this paper, the authors attempt to axiomatize the extending mechanism of solutions to these systems, merely starting from several basic axiomatized conditions such as the local existence, joint property of solutions and some energy inequalities. The results established have nothing to do with the concrete forms of the systems and, thus, give the extending mechanisms in a unified way to all systems obeying the axiomatized conditions. The key tools are several new multiplicative interpolation inequalities of Besov type, which have their own interests.

关键词： Interpolation inequalities of Besov type Blow-up criteria Navier-Stokes equations

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Ultradense Sphere Packings Derived From Disordered Stealthy Hyperuniform Ground States

arXiv

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arXiv 2025年

作者： Kim, Jaeuk Torquato, Salvatore Princeton Materials Institute Department of Physics Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Chemistry Department of Physics Princeton Materials Institute Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Disordered stealthy hyperuniform (SHU) packings are an emerging class of exotic amorphous two-phase materials endowed with novel optical, transport, and mechanical properties. Such packings of identical spheres have been created from SHU ground-state point patterns via a modified collective-coordinate optimization scheme that includes a soft-core repulsion, besides the standard "stealthy" pair potential. To explore maximal ranges of the packing fraction , we investigate the distributions of minimum pair distances as well as nearest-neighbor distances of ensembles of SHU point patterns without and with soft-core repulsions in the first three space dimensions as a function of the stealthiness parameter χ and number of particles N within a hypercubic simulation box under periodic boundary conditions. Within the disordered regime (χ max(χ, d), decrease to zero on average as N increases if there are no soft-core repulsions. By contrast, the inclusion of soft-core repulsions results in very large max(χ, d) independent of N, reaching up to max(χ, d) = 1.0, 0.86, 0.63 in the zero-χ limit and decreasing to max(χ, d) = 1.0, 0.67, 0.47 at χ = 0.45 for d = 1, 2, 3, respectively. We obtain explicit formulas for max(χ, d) as functions of χ and N for a given value of d in both cases with and without soft-core repulsions. In two and three dimensions, our soft-core SHU ground-state packings for small χ become configurationally very close to the corresponding jammed hard-particle packings created by fast compression algorithms, as measured by their pair statistics. As χ increases beyond 0.20, the packings form fewer contacts and linear polymer-like chains as χ tends to 1/2. The resulting structure factors S(k) and pair correlation functions g2(r) reveal that soft-core repulsions significantly alter the short- and intermediate-range correlations in the SHU ground states. We show that the degree of large-scale order of the soft-core SHU ground states increases as χ increases from 0 to

关键词： Digital arithmetic

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Distributing pairs of vertices on Hamiltonian cycles

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Science China mathematics 2018年第5期61卷 955-972页

作者： Weihua He Hao Li Qiang Sun Department of Applied Mathematics Guangdong University of Technology Laboratoire de Recherche en Informatique CNRS-Université Paris-Sud Institute for Interdisciplinary Research Jianghan University School of Mathematical Science Yangzhou University

Let G be a graph of order n with minimum degree δ(G)≥n/2+1. Faudree and Li(2012) conjectured that for any pair of vertices x and y in G and any integer 2≤k≤n/2, there exists a Hamiltonian cycle C such that the distance between x and y on C is k. In this paper, we prove that this conjecture is true for graphs of sufficiently large order. The main tools of our proof are the regularity lemma of Szemer′edi and the blow-up lemma of Koml′os et al.(1997).

关键词： Hamiltonian cycle Faudree-Li conjecture regularity lemma blow-up lemma

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The split common fixed point problem for infinite families of demicontractive mappings

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Fixed Point Theory and Applications 2018年第1期2018卷 1-21页

作者： Hanjing, Adisak Suantai, Suthep Ph.D. Degree Program in Mathematics Faculty of Science Chiang Mai University Chiang Mai Thailand Center of Excellence in Mathematics and Applied Mathematics Department of Mathematics Faculty of Science Chiang Mai University Chiang Mai Thailand Center of Excellence in Mathematics CHE Bangkok Thailand

In this paper, we propose a new algorithm for solving the split common fixed point problem for infinite families of demicontractive mappings. Strong convergence of the proposed method is established under suitable control conditions. We apply our main results to study the split common null point problem, the split variational inequality problem, and the split equilibrium problem in the framework of a real Hilbert space. A numerical example supporting our main result is also given. © 2018, The Author(s).

关键词： Demicontractive mappings Equilibrium problem Fixed point problem Null point problem Variational inequality problem

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Innovation and utilization of coffee skin waste (Coffea robusta L) as a superior compost for the growth of pepper cuttings (Piper nigrum L.)

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AIP Conference Proceedings 2025年第1期3186卷

作者： Awalul Fatiqin Dewi Lestari R. A. Hoetary Tirta Amalia Riri Novita Sunarti Ike Apriani Anita Restu Puji Raharjeng Rr Mini Sari Wulan Thathit Suprayogi Yahya Febrianto Sudarman Rahman Shesanthi Citrariana Rokiy Alfanaar Mu’afa Purwa Arsana Yithro Serang Wansadaj Jaroenram Biology Study Program Faculty of Mathematics and Natural Sciences Palangka Raya University Palangka Raya Central Kalimantan Indonesia Biology Study Program Faculty of Science and Technology Universitas Islam Negeri Raden Fatah Palembang Palembang South Sumatra Indonesia Education Biology Study Program Faculty of Teacher Training and Education Universitas Islam Negeri Raden Fatah Palembang Palembang South Sumatra Indonesia Physics Study Program Faculty of Mathematics and Natural Sciences Palangka Raya University Palangka Raya Central Kalimantan Indonesia Pharmacy Study Program Faculty of Mathematics and Natural Sciences Palangka Raya University Palangka Raya Central Kalimantan Indonesia Chemistry Study Program Faculty of Mathematics and Natural Sciences Palangka Raya University Palangka Raya Central Kalimantan Indonesia Mathematics Study Program Faculty of Mathematics and Natural Sciences Palangka Raya University Palangka Raya Central Kalimantan Indonesia Department of applied chemistry Chaoyang University of Technology Taichung City Taiwan National center for genetic engineering and biotechnology (BIOTEC) Pathum Thani Thailand

This study aimed to determine the potential of coffee skin waste (Coffea robusta L) as a superior compost innovation for the growth of pepper-cutting seedlings (Piper nigrum L). This study used an experimental method with a completely randomized design using five treatments and five repeats, variations in the dose of coffee skin waste used P0 (control), P1 (90 g), P2 (135 g), P3 (180 g), and P4 (225 g). The shoot height, number of leaves, number of roots, and length of roots were measured. The results showed that coffee skin waste compost significantly affected shoot height, especially at P1 (90 g), resulting in an average growth height of 7.24 cm. In addition, the highest number of leaves was found at a concentration of P1 (90 g), with an average of two leaves. Although there was no significant effect on the number of roots, the concentration of P1 (90 g) yielded the best results, with an average of 33 root blades, and the best root length was obtained at the concentration of P1 (90 g), with an average of 44.6 cm. Therefore, coffee skin waste significantly influenced shoot height and the number of leaves on pepper-cut seedlings (Piper nigrum L.) in the P1 treatment (90 g).

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THE EVOLUTION OF DISTURBANCES IN AN EKMAN BOUNDARY-LAYER

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JOURNAL OF FLUID MECHANICS 1982年第FEB期115卷 327-346页

作者： SPOONER, GF CRIMINALE, WO Department of Oceanography University of Washington Seattle Washington 98195 U.S.A. Also at Applied Mathematics Group Geophysics Program University of Washington Seattle.

A linear model of a wave packet in a laminar Ekman boundary layer is proposed for tracing the development of an initially localized pulsed perturbation at the boundary. The model disturbance was built up from a linear combination of growing modes summed numerically over all wavenumbers and frequencies. The input spectrum was assumed to be flat so that there was no biasing at any wavenumber or frequency and the evolution was calculated on the basis of linear-stability theory. The wave packet generated by the summation of modes developed uniformly downstream of the disturbance source location and, depending upon the choice of the Reynolds number, vividly displayed results representative of the different kinds of instabilities that are present in the Ekman layer. Outputs in the form of perspective plots are given in order to explain the evolution of the packet into either a single wave patch or a sum of individual wave patches.

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Differentiable Simulator For Dynamic & Stochastic Optimal Gas & Power Flows 63

Differentiable Simulator For Dynamic & Stochastic Optimal Ga...

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63rd IEEE Conference on Decision and Control, CDC 2024

作者： Hyett, Criston Pagnier, Laurent Alisse, Jean Goldshtein, Igal Saban, Lilah Ferrando, Robert Chertkov, Michael University of Arizona Program in Applied Mathematics & Department of Mathematics TucsonAZ United States Noga the Israel Independent System Operator Haifa Israel

ISBN: (纸本)9798350316339

In many power systems, particularly those isolated from larger intercontinental grids, reliance on natural gas is crucial. This dependence becomes particularly critical during periods of volatility or scarcity in renewable energy sources, further complicated by unpredictable consumption trends. To ensure the uninterrupted operation of these isolated gas-grid systems, innovative and efficient management strategies are essential. This paper investigates the complexities of achieving synchronized, dynamic, and stochastic optimization for autonomous transmission-level gas-grid infrastructures. We introduce a novel methodology grounded in differentiable programming, which synergizes symbolic programming, a conservative numerical method for solving gas-flow partial differential equations, and automated sensitivity analysis powered by SciML/Julia. Our methodology refines the co-optimization landscape for gas-grid systems by grounding gas dynamics in physics-adherent simulation. We demonstrate efficiency and precision of the methodology by solving a stochastic optimal gas flow problem, phrased on an open source model of Israel's gas grid model. © 2024 IEEE.

关键词： Sensitivity analysis

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