Thermal noise in amorphous coatings is a limitation for a wide range of
precision experiments such as gravitational-wave detectors (GWDs). Mirrors for
GWDs are composed of multiple thin layers of ...dielectric materials deposited on
a substrate: the stack is made of layers with a high refractive index
interleaved with layers of a low refractive index. The goal is to obtain high
reflectivity and low thermal noise. In this paper we report on the optical and
mechanical properties of ion-beam-sputtered aluminium fluoride (AlF$_3$) thin
films which have one of the lowest refractive index among the known coating
materials and we discuss their application in current and future GWDs.
Phys. Rev. Applied 17 (2022) 034058 Brownian thermal noise associated with highly reflective coatings is a
fundamental limit for several precision experiments, including
gravitational-wave detectors. ...Research is currently ongoing to find coatings
with low thermal noise that also fulfill strict optical requirements such as
low absorption and scatter. We report on the optical and mechanical properties
of ion-beam-sputtered magnesium fluoride thin films, and we discuss the
application of such coatings in current and future gravitational-wave
detectors.
Thermal noise in amorphous coatings is a limitation for a wide range of precision experiments such as gravitational-wave detectors (GWDs). Mirrors for GWDs are composed of multiple thin layers of ...dielectric materials deposited on a substrate: the stack is made of layers with a high refractive index interleaved with layers of a low refractive index. The goal is to obtain high reflectivity and low thermal noise. In this paper we report on the optical and mechanical properties of ion-beam-sputtered aluminium fluoride (AlF\(_3\)) thin films which have one of the lowest refractive index among the known coating materials and we discuss their application in current and future GWDs.
Brownian thermal noise associated with highly reflective coatings is a fundamental limit for several precision experiments, including gravitational-wave detectors. Research is currently ongoing to ...find coatings with low thermal noise that also fulfill strict optical requirements such as low absorption and scatter. We report on the optical and mechanical properties of ion-beam-sputtered magnesium fluoride thin films, and we discuss the application of such coatings in current and future gravitational-wave detectors.
•A control-oriented 0-D model of VRFB cell is proposed.•Precise simulation of crossover is performed.•Analytical solution for crossover flux with all three modes is elaborated.•Contribution of ...different crossover components to the capacity decay is investigated.
A 0-D dynamic mathematical model for a single Vanadium Redox Flow Battery (VRFB) cell is proposed. The model is based on the conservation principles of charge and mass transfer focusing on the precise simulation of crossover with diffusion, migration and convection. The influence of these phenomena on the capacity decay was systematically analyzed, revealing considerable impact of convection component, which dominates under diffusion and migration and mainly responsible for observed capacity loss. The model allows to simulate main characteristics of VRFB systems (such as battery voltage, state of charge, charge/discharge time and capacity decay due to crossover) with high accuracy. The model was validated with experimental data in the wide range of current densities (40–100 mA cm−2), and the results demonstrated good agreement with experiments having an average error within 5% range. In addition, the model requires a modest computational time and power, and, therefore, it can be suitable for application in advanced control-monitoring tools, which are necessary for a long-service life and sustainable operation of VRFB systems.
•A new approach for estimation of key VRFB parameters is proposed.•A kilo-watt class VRFB system energy efficiency is analyzed (5 kW/15kWh).•Voltage losses and capacity decay for charge and discharge ...processes are analyzed.•Contribution of internal processes to the voltage and capacity losses is analyzed.•Analytical dependencies for voltage and coulombic efficiencies are proposed.
A new methodology for estimation of the key characteristics of commercial scale Vanadium Redox Flow Battery (VRFB) at different operating conditions is proposed. The method is based on a set of simplified correlations that allow estimating VRFB rated power, capacity and operation time directly from the geometry of stack and tank without detailed numerical simulation of the battery. The study is focused on investigation of a kilo-watt class VRFB system (5 kW/15kWh) considering a wide range of current densities (40–100 mA cm−2). The proposed simplified approach is validated considering the most representative cases of battery operation strategies related to slow and fast modes. It demonstrated high accuracy for the estimation of rated power and operation time (average error below 3%) as well as stored energy (average error below 6%) compare to results of detailed numerical simulation. As a result, the proposed methodology can be used as a simple tool for development of proper battery usage protocol (a schedule for battery usage), which could allow avoiding over/underestimation of committed battery energy and power during battery operation. In addition, the obtained results can be also used in order to improve the accuracy of techno-economic studies determining the most economically attractive cases for application of VRFB systems.
In this paper, we propose a new strategy for electrolyte flow rate control in Vanadium Redox Flow Batteries. The keystone of our approach is a novel methodology for determination of optimal reference ...voltage and robust feedback controller design that provides the desired transient and steady state battery performance. In addition, we introduce a hierarchical scheme of the general battery control system that significantly simplifies classification of battery control tasks and gives guidelines for multistage controller design. The research considers a kilo-watt class VRFB system operating in a wide range of loading currents (20–180 A). The proposed control algorithm allows reference trajectory tracking with high accuracy (average error less than 0.0005%), yet providing the required battery performance at twice lower flow rates as compared to the existing solutions, and thus, decreasing pump energy consumption by a factor of 3. As a result, the proposed method can be used for flow rate regulation in practical VRFB systems ensuring their stable and efficient operation under dynamic loading conditions.
•A new approach for flow rate control in VRFB systems is proposed.•A kilo-watt class VRFB system is considered (5 kW/15 kWh).•A hierarchical classification of tasks related to flow rate regulation is proposed.•The control strategy is based on proportional-and-integral controller.•The designed controller assures stable VRFB operation at dynamic loads.
