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Rarefied gas effects are of critical importance for the aerodynamic performance of hypersonic vehicles operating at high altitudes. In these scenarios, conventional computational fluid dynamics (CFD) solvers break down as the linear…

Fluid Dynamics · Physics 2026-05-25 Wenpei Long , Junzhe Cao , Yue Zhang , Kun Xu

This paper proposes a convex optimization based distributed algorithm to solve multi-period optimal gas-power flow (OGPF) in coupled energy distribution systems. At the gas distribution system side, the non-convex Weymouth gas flow…

Optimization and Control · Mathematics 2016-10-18 Cheng Wang , Wei Wei , Jianhui Wang , Linquan Bai , Yile Liang

The equations governing one-dimensional, steady-state electrodiffusion are considered when there are arbitrarily many mobile ionic species present, in any number of valence classes, possibly also with a uniform distribution of fixed…

Quantitative Methods · Quantitative Biology 2017-02-23 A. J. Bracken , L. Bass

In this work we analyse a stochastic control problem for the valuation of a natural gas power station while taking into account operating characteristics. Both electricity and gas spot price processes exhibit mean-reverting spikes and…

Mathematical Finance · Quantitative Finance 2016-08-02 Nemat Safarov , Colin Atkinson

We present a pure linear cutting-plane relaxation approach for rapidly proving tight and accurate lower bounds for the Alternating Current Optimal Power Flow Problem (ACOPF) and its multi-period extension with ramping constraints. Our…

Optimization and Control · Mathematics 2024-09-19 Daniel Bienstock , Matias Villagra

The hypersonic flow around near-space vehicles constitutes a multi-scale flow problem. Due to insufficient molecular collisions to achieve equilibrium, rarefied gas effects are present in the flow field. Thus, numerical methods capable of…

Fluid Dynamics · Physics 2025-07-02 Sirui Yang , Chengwen Zhong , Ningchao Ding , Junzhe Cao , He Zhang , Congshan Zhuo , Sha Liu

The ever increasing utilization of sensitive loads in the industrial, commercial and residential areas in distribution networks requires enhanced reliability and quality of supply. This can be achieved thanks to self healing features of…

Optimization and Control · Mathematics 2018-04-18 Hossein Sekhavatmanesh , Rachid Cherkaoui

The optimization of well locations and controls is an important step in the design of subsurface flow operations such as oil production or geological CO2 storage. These optimization problems can be computationally expensive, however, as…

Geophysics · Physics 2024-05-16 Haoyu Tang , Louis J. Durlofsky

Gaseous flows under an external force are intrinsically defined by their multi-scale nature due to the large variation of densities along the forcing direction. Devising a numerical method capable of accurately and efficiently solving…

Computational Physics · Physics 2025-07-15 Shuangqing Liu , Zuoxu Li , Yonghao Zhang , Tianbai Xiao

The gap equations lie at the core of the Bardeen-Cooper-Schrieffer (BCS) theory, a standard tool in the description of superfluidity. As a set of non-linear integral equations, the gap equations' inherent difficulties oftentimes hinder even…

Nuclear Theory · Physics 2025-10-10 Georgios Palkanoglou , Alexandros Gezerlis

We study the static equilibria of a simplified Leslie--Ericksen model for a unidirectional uniaxial nematic flow in a prototype microfluidic channel, as a function of the pressure gradient $\mathcal{G}$ and inverse anchoring strength,…

Analysis of PDEs · Mathematics 2017-06-28 Maria Crespo , Ian Griffiths , Apala Majumdar , Angel Ramos

Ensuring the safe and reliable operation of integrated electricity and gas systems (IEGS) requires dynamic energy flow (DEF) simulation tools that achieve high accuracy and computational efficiency. However, the inherent strong nonlinearity…

Systems and Control · Electrical Eng. & Systems 2025-02-28 Zhikai Huang , Shuai Lu , Wei Gu , Ruizhi Yu , Suhan Zhang , Yijun Xu , Yuan Li

The well-known Navier--Stokes--Fourier equations of fluid dynamics are, in general, not adequate for describing rarefied gas flows. Moreover, while the Stokes equations -- a simplified version of the Navier--Stokes--Fourier equations -- are…

Fluid Dynamics · Physics 2025-03-21 Himanshi , Anirudh Singh Rana , Vinay Kumar Gupta

The power flow equations are at the core of most of the computations for designing and operating electric power systems. The power flow equations are a system of multivariate nonlinear equations which relate the power injections and…

Optimization and Control · Mathematics 2016-11-17 Dhagash Mehta , Daniel K Molzahn , Konstantin Turitsyn

We demonstrate that valid inequalities, or lifted nonlinear cuts (LNC), can be projected to tighten the Second Order Cone (SOC), Convex DistFlow (CDF), and Network Flow (NF) relaxations of the AC Optimal Power Flow (AC-OPF) problem. We…

Optimization and Control · Mathematics 2024-09-27 Sergio I. Bugosen , Robert B. Parker , Carleton Coffrin

Security-constrained unit commitment with alternating current optimal power flow (SCUC-ACOPF) is a central problem in power grid operations that optimizes commitment and dispatch of generators under a physically accurate power transmission…

Optimization and Control · Mathematics 2025-05-12 Matthew Brun , Thomas Lee , Dirk Lauinger , Xin Chen , Xu Andy Sun

Nonlinearity continuation method, applied to boundary value problems for steady-state Richards equation, gradually approaches the solution through a series of intermediate problems. Originally, the Newton method with simple line search…

Numerical Analysis · Mathematics 2021-05-27 Denis Anuprienko

In this paper, we present decomposition techniques for solving large-scale instances of the security-constrained optimal power flow (SCOPF) problem with primary response. Specifically, under each contingency state, we require that the nodal…

Optimization and Control · Mathematics 2019-10-10 Alexandre Velloso , Pascal Van Hentenryck , Emma S. Johnson

This paper presents heavily grad-div and pressure jump stabilised, equal- and mixed-order discontinuous Galerkin finite element methods for non-isothermal incompressible flows based on the Oberbeck-Boussinesq approximation. In this…

Numerical Analysis · Mathematics 2017-08-16 Philipp W. Schroeder , Gert Lube

This letter investigates properties of the second-order cone relaxation of the optimal power flow (OPF) problem, with emphasis on relaxation tightness, nodal voltage angles recovery, and alternating-current-OPF feasibility in meshed…

Systems and Control · Electrical Eng. & Systems 2026-02-20 Ginevra Larroux , Matthieu Jacobs , Mario Paolone