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The operation and repair of locomotives is characterized by indicators that assess the quality of the repair and maintenance work performed. The article considers a new indicator that characterizes the quality of work of locomotive repair enterprises of service companies. The components of the equation are investigated and the procedure for calculating the coefficient of technical readiness is analyzed. It has been established that there is a time that is taken into account separately for the responsibility of the repair and maintenance company and is Administrative costs. In order to obtain a tool to increase the time spent by locomotives in working condition, it is offered to use simulation dynamic models. The main stages and results of constructing a simulation model of a typical technical inspection point for locomotives are considered. Dependent events were identified and the degree of influence was assessed. The conclusions are drawn that the current version of the simulation dynamic model can be considered a digital twin, because it is a digital copy of the existing physical process for loading the production section. [ABSTRACT FROM AUTHOR]

As the most widely applied heaters and recuperators in supercritical CO2 (sCO2) power cycles, the Printed Circuit Heat Exchangers (PCHEs) received considerable interests in their transient behavior simulation. After an introduction and comparison about the state-of-art PCHEs numerical simulation approaches, this paper presents a generic one-dimensional (1D) numerical PCHEs modelling methodology featured for 1) ability fulfilling transient simulation; 2) precise capture of the sharp local variations in sCO2 thermo-physical properties. The dynamic simulation ability of the proposed 1D modelling methodology is justified by validating its Modelica implementation against experimental results measured at the Pinjarra Hills High Pressure Loop, the University of Queensland. The proposed PCHE model successfully predicts the changing trends in the temperature and mass flow rate of the working fluids except for a minor time delay. Therefore, the PCHE model is verified as a proper simulation tool for control strategy development for the sCO2 power cycle simulation study. [ABSTRACT FROM AUTHOR]

Model Predictive Control (MPC) can be used to achieve offset-free control utilizing an observer. The use of an observer is problematic when the observability is low and may add additional tuning problems. A combined MPC, based on a min-max configuration, is combined with an integral controller as an alternative way of introducing integral action and achieving offset-free control. The controller setup is tuned for control of a distillation unit, which is a non-linear system with considerable interactions when using LV-configuration and controlling both top and bottoms products. The suggested controller is tested using a dynamic model for simulation of the distillation unit. The control simulations show that the proposed technique can achieve good performance, achieving offset-free control and not many oscillations, for both disturbance rejection and set-point tracking. [ABSTRACT FROM AUTHOR]

The paper describes numerical simulations with a meso-scale discrete model, specifically the Lattice Discrete Particle Model (LDPM). The Voronoi tessellation is used to build the random geometry of the model. The previous solver was capable to simulate only static behavior of the concrete, development of the dynamic solver is the contribution of the present work. The simulation of the dynamic response is based on the implicit generalized-alpha method. A mass matrix involving translational and rotational inertia as well as eccentricity of the centroid of the particle is derived. Numerical examples of the simple cantilever beam loaded by single force at the free end are used to verify the transient response of the linear elastic material, in our case the plain concrete. Computed results with different model settings are compared with the analytical solution and static response. [ABSTRACT FROM AUTHOR]

Parabolic trough collector (PTC) systems are commercially available concentrating solar power plants widely known for their application to generate electrical power. To further reduce the dependency on fossil fuels, such systems can also be deployed for producing process heat for industrial purposes. In combination with a thermal energy storage system, this technology has the ability to reliably supply on-demand process heat. This paper gives details on a fully automated PTC system with concrete thermal energy storage (C-TES) and kettle-type boiler that supplies saturated steam for a beverage factory in Limassol, Cyprus. In the focus is the validation of a dynamic simulation model in Modelica® that physically describes the entire PTC system. The simulation model uses various plant data as inputs including mirror reflectivity and weather data from on-site measurements. The validation was carried out in three steps. First, the PTC was validated as a stand-alone component. A time-dependent inlet oil temperature vector was given as input and the outlet oil temperature was computed. The root mean square (rms) error between the measured to simulated outlet oil temperature values results in 3.86% (equivalent to about 1.9 K). The second part of the validation then considered a complete PTC oil cycle in PTC-and-boiler operation mode (without C-TES). In the simulation, both the PTC inlet and outlet oil temperatures were computed. The result is a deviation < 4.25 % (rms) between measured to simulated values. Finally, in the third step, the C-TES model was validated as a stand-alone component. The deviation between measurement and simulated values is < 5% compared to the design point. [ABSTRACT FROM AUTHOR]