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VRML (Virtual Reality Modeling Language) is a nonproprietary language used for scientific simulation and visualization. VRML alone do not have the capability of holding numerical values but with the help of slider design, the numeric values can be dynamically varied. The VRML Graphic User Interface (GUI) presented in this paper demonstrates dynamic simulation of Seed Grader Machine Parameters and its effect on final output. This paper describes how VRML capabilities can be utilized for simulating Seed Grader Machine Parameters in virtual Environment. The concept can be applied for variety of applications involving similar requirements.

Extensive reviews and cross-comparison studies are essential to analyze the emerging developments in a specific field of research. In the past decade, hydrocarbon exploration and exploitation from the shale reservoirs have been the most discussed and researched area around the globe. A dramatic development in shale formations became the game-changer, especially in the US. On the other hand, Artificial Intelligence (AI) and Machine Learning (ML) are playing an important role in the rapid development in all the industries through automating most of the routine operations. The oil industry is also getting equal benefits of AI and ML for the reservoir development planning and its operational accuracy through a series of automated systems. For the field development, computerized static and dynamic simulation models are generated based on several Petrophysical and Geomechanical properties gathered through different resources that are quite a time taking and expensive. AI and ML have made this process much easier, faster, and economical by means of learning through uncounted experiences from already explored and developed reservoirs, their rock properties, and the cross-ponding fluid flow behavior under different circumstances and hence, predicts accordingly. This article provides a comprehensive literature review in the area of AI and ML application to model Petrophysical and Geomechanical properties using different approaches and algorithms. Also, a systematic publication counts in each field of subject study per year in different literature databases are presented that infect reflects the trending interest in this subject. Finally, multiple AI and ML techniques are discussed in detail that has been tested in the last decade for the sake of achieving more accuracy in Petrophysical and Geo-Mechanical simulation models.

Pipeline inner inspection technology based on Pipeline Inspection Gauge (PIG), is the primary means for ensuring the safety of submarine pipelines. The dynamic characteristics of a PIG can change abruptly with the excitation of obstacles such as girth welds inside the pipeline, which would result in failure or inaccuracy of the inspection results. This study establishes a dynamic model of the PIG sealing disc based on Kelvin spring damping in the circumferentially confined space. The axial vibration differential equations of the PIG is examined in detail. MSC/ADAMS is used to conduct the dynamic simulation of the PIG at different motion velocities and center of mass positions while passing through the girth weld process. Results indicate that the axial vibration caused by the girth weld intensifies substantially as the speed of the PIG increases, while the pitch and vertical vibrations exhibit a significant decline with an increase in the motion velocity. The change in the PIG’s center of mass positions has little effect on its axial vibration, while the pitch and vertical vibration conditions are significantly different in the same circumstances.

This article describes a soft robot based on boundary constrained modular subunits. The loop-shaped robot consists of a granule-filled elastic toroidal membrane with a series of modular subunit robots attached to its exterior. The robot can operate both as a soft robot to conform to external objects or navigate through narrow corridors and as a rigid robot by jamming its internal granules using a vacuum. The jammed state is useful for exerting forces on the environment in object manipulation or locomotion tasks. This article describes the robot’s design, object handling capabilities, locomotion, shape formation, and ability to navigate narrow corridors. We also present computationally efficient control methodologies used for self-reconfiguration and target tracking, which enable scaling the number of subunits to create larger systems. The robot’s scalability and the control methodologies are verified through simulation with ProjectChrono, a multibody dynamic simulation platform. All other results are obtained experimentally.

This paper describes algorithms for the animation of men and women performing three dynamic athletic behaviors: running, bicycling, and vaulting. We animate these behaviors using control algorithms that cause a physically realistic model to perform the desired maneuver. For example, control algorithms allow the simulated humans to maintain balance while moving their arms, to run or bicycle at a variety of speeds, and to perform a handspring vault. Algorithms for group behaviors allow a number of simulated bicyclists to ride as a group while avoiding simple patterns of obstacles. We add secondary motion to the animations with spring-mass simulations of clothing driven by the rigid-body motion of the simulated human. For each simulation, we compare the computed motion to that of humans performing similar maneuvers both qualitatively through the comparison of real and simulated video images and quantitatively through the comparison of simulated and biomechanical data., Alternate location: http://graphics.berkeley.edu/papers/Hodgins-AHA-1995-08 8 pages, figures

This paper presents a dynamical analysis of a tethered aerostat using a multibody simulation tool called SimscapeMultibody™. Tethered aerostats are lighter than air vehicles that float in the air and are connected to the ground through the tether. Atmospheric winds are a source of disturbance to the aerostat. The wind produces drag force that causes the aerostat to displace from its mean position. This phenomenon is called blow-by. Solving the mathematical model of the motion dynamics with time step is the conventional method used for simulating the flight dynamics of the aerostat. This paper discusses the application of Simscape Multibody™ for the three-degrees-of-freedom flight dynamic simulation of spherical tethered aerostat. Simscape Multibody™, an extension of MATLAB®/Simulink, is a multibody modeling tool in which physical bodies and their interactions have to be defined to simulate the dynamics. The mathematical model of the defined system is automatically generated by the SimscapeMultibody™ solver, and the system dynamics is simulated. The simulation of dynamics using multibody modeling tools provides high fidelity simulation for the tethered aerostats.

Hinged booms are widely used in astrophysics missions; however, the trajectory and deployment velocity are difficult to control because they are usually driven by springs, which limits their application in narrow spaces. Thus, a novel hinged boom is highly required to achieve motion controllability. Through an equivalent substitution between the cable drive loop and the binary link in topology, a type synthesis method for the cable-driven single-degree-of-freedom chain is proposed based on the single-open-chain (SOC) adding method. According to the configuration design, a novel cable-driven hinged boom is proposed, aiming to achieve boom synchronism. Then, to preload easily, a method that preload is applied and measured at the cable ends is adopted and the relationship between the initial preload and the target preload is deduced. By analyzing the distribution of cable tension, a new stiffness model is proposed thus a stiffness equation is obtained. Finally, the dynamic simulation analysis and zero-gravity deployment experiment of the hinged boom is carried out to verify its reliability. This research provides a new way for the type synthesis of cable-driven single-degree-of-freedom chain and a new model for analyzing cable-driven stiffness. Moreover, the novel cable-driven hinged boom obtained in this study can be well-applied in the field of aerospace.

The industrial sector is one of the biggest oil consumers in Cyprus, corresponding to 20% of the fuel consumption. A parabolic trough collector (PTC) system seems the best option to produce clean thermal energy at higher temperatures than those that can be achieved from the already widely used flat plate collectors on the island. This paper presents a simulation model built to investigate the performance of the first industrial PTC system in Cyprus, installed at the Cyprus biggest soft drinks factory. The simulation model is built in TRNSYS and is validated using data from the real PTC system installed at the factory. The results show a very good fitting between the operating parameters and the power output of the Solar Field (SF), Concrete Thermal Storage System (CTES), and the Steam Generator (SG). The average percentage relative error of the system's contribution to the process is less than 6.32% for the daily steam production and during a week did not exceed 6.45%. The novelty of this study is the development of a design tool that can be used by potential interested industries to identify the suitable system that fits their needs. All data are provided in the form of graphs and allow anyone to use as input data the thermal energy demand and required steam temperature of the industry to retrieve information about the size of a suitable system which satisfies these requirements depending on each case. The payback period for all cases examined varies from 2 to 6 years, depending on the size of the system.

The rapid deployment of distributed energy resources (DERs) in distribution networks has made it challenging to balance the transmission system and stabilize frequency. DERs have the ability to provide frequency regulation services; however, existing frequency dynamic simulation tools—which were developed mainly for the transmission system—lack the capability to simulate distribution network dynamics with high penetrations of DERs. Although electromagnetic transient simulation tools can simulate distribution network dynamics, the computation efficiency limits their use for large-scale transmission-and-distribution (T&D) co-simulation. This paper presents an efficient open-source T&D dynamic co-simulation framework for DER frequency response based on the HELICS platform and off-the-shelf T&D simulators. The challenge of synchronizing the simulation time between the transmission network and the DERs in the distribution network is solved through the detailed modeling of DERs in frequency dynamic models while DER power flow models are also preserved in the distribution networks, thereby respecting local voltage constraints when dispatching DER power for frequency response. DER frequency response (primary and secondary) is simulated in case studies to validate the proposed framework. Last, the accuracy of the proposed co-simulation model is benchmarked, and a large T&D system simulation (2k transmission and 1M distribution nodes) is presented to demonstrate the efficiency and effectiveness of the overall framework.

The research is aimed at the study and validation of an impact attenuator to be installed on roads. Its main function is to absorb the energy generated by an impact, therefore, the different regulations (national and international) are analyzed together with the materials that lead to reduce the severity of the accident. From this point, the best material is selected through a decision matrix under specific parameters, the design of the shape of the attenuator using a Pugh matrix ideal for the selection of completely new designs and the dynamic simulation is established to observe the behavior. The modeling of the attenuator geometry is created by engineering software and its geometry itself, it is designed in sections with mitigating elements among them. For the validation of the design, the one with the greatest capacity to dissipate energy is chosen, for this purpose, the behavior of the impact attenuator in the event of a vehicle crash is observed using finite element analysis software, defining simulation variables and varying geometry parameters, resulting after several simulations that the 0.8 mm thick impact attenuator design is the most suitable to reduce the crashing effect by reducing the kinetic energy of the rigid body by 92.72%.

This works aims at evaluating different process configurations for producing solketal from reacting glycerol with acetone. The research carries out the regression of thermodynamic and kinetic parameters, rigorous design of four process configurations, optimization, carbon emission analysis, and control. The results from steady-state analysis reveal that the solvent-free coupled reaction/distillation (SFCRD) process is the most promising. It reduces 40.09% of total annual cost and 45.09% of CO2 emission from the base case, the separated reactor-distillation process. Besides, the CO2 emission rate of the SFCRD process is found 35.29% and 65.91% less than the recently reported upper and the middle partition reactive dividing-wall column process, respectively, indicating the unfavorability of intensifying this reacting system through reactive distillation. Finally, a control structure for the SFCRD process is established for effectively handling the disturbances from the flowrate, composition and catalyst deactivation. Through the dynamic simulation, the closed-loop control results were revealed satisfactory.

The rotating packed bed (RPB) has been widely used in gas-liquid flow systems as a process intensification device, exhibiting excellent mass transfer enhancement characteristics. However, the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods. In the past two decades, Computational Fluid Dynamics (CFD) has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design. This article covers the development of the CFD simulation of gas-liquid flow in RPB. Firstly, the improvement of the simulation method in the aspect of mathematical models, geometric models, and solving methods is introduced. Secondly, new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed, including pressure drop, velocity distribution, flow pattern, and concentration distribution, etc. Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works. In addition, the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different applications. The defects of current research and future development directions are also discussed at last.

This paper presents the study of binary component analysis subjected to distillation process using Aspen Plus. Binary components namely Isopropyle alcohol and water were considered for the study and their characteristics are analyzed at certain temperature and pressure. Aspen Plus provides virtual exposure of physical process, gives quantitative measure of mole fraction of liquid phase, vapor phase with changes in temperature, pressure and activity coefficients. Steady state and dynamic simulation results depicts the behavior of the system and enables the user to understand how the system reacts in virtual environment, to realize the system behavior in real-time environment.

To study the internal flow characteristics of the photovoltaic pump under the transient change of solar radiation, the simulation algorithm of the photovoltaic pump system was established by MATLAB/Simulink and CFD for the first time and the results were validated by the test. Firstly, the change rule of pump flow rate and rotation speed under transient solar radiation was obtained by Simulink. Then the results of the change rule were transformed into the boundary condition of CFD by CEL function and the transient flow field in the photovoltaic pump was obtained. The internal flow characteristics and pressure pulsation in the pump were analyzed when the solar radiation increases or decreases transiently. The results demonstrate that the numerical calculation can provide accurate prediction for the characteristics of internal flow in the pump. The numerical results are closed to the experimental results, the minimum error of pressure is 0.93% and the maximum error is 1.78%. When the solar radiation increases transiently, the low pressure area at the impeller inlet gets larger obviously and the jet-wake at the impeller outlet becomes more obvious. The pressure pulsation in the impeller gradually increases and becomes stable after 0.6 s. The pressure from the impeller outlet to the guide vane outlet is stable at 123 kPa. When the solar radiation decreases transiently, the pressure in the impeller takes 1.6 s to be stable. Larger pressure pulsation occurs from the impeller outlet to the guide vane inlet and the maximum differential pressure is 10 kPa. Compared with the transient increase of solar radiation, the pressure in the impeller takes over 0.2 s to stabilize when the solar radiation transient decreases. Meanwhile, the results in this paper can provide references for other transient characteristics research. Highlight First, the relation between pump flow rate and rotation speed under transient solar radiation was obtained by Simulink. Then the results from Simulink were transformed to be the boundary condition of CFD by CEL function. The internal flow characteristics and pressure pulsation in the pump were analyzed under the instantaneous increase or decrease of the solar radiation.

Extracting thermal energy from medium-deep ground layer for building heating is a promising means for pushing forward cleaner heating initiative. There is no available analytical model that can provide fast, accurate and effective simulation of both fluid and soil temperature field of deep borehole heat exchanger (DBHE) under complex geothermal gradient and subsurface stratifications. In this study, a stratified segmented finite line source method (SS-FLS) is proposed as an main contribution and novelty. The proposed model is validated by comparing with finite element method, model degradation example, and actual engineering project data of DBHE. The accuracy and robustness of the SS-FLS is fully checked. Then the effects of stratification on soil temperature field and fluid temperature field are investigated. It is found that the shape of temperature contour and temperature distribution have direct link with stratification as well as heat extraction rate on the heat pump side. Moreover, two critical model parameters are discussed in details which poses an important guide for both model application and system analysis.

Sensible thermal energy storage is the most common solution for small-to-medium solar process heat systems. Hence, it is vital to enhance the thermal stratification and energy utilization of stratified tanks. In this study, four process heat systems are dynamically simulated: 1) S0 with a single outlet port to the load, 2) S1 with a single port and a thermostatic mixing valve, 3) M0 with multiple ports, and 4) M1 with multiple ports and a mixing valve. Two novel models are proposed for the compound parabolic collectors and the stratified tanks. System M1, with annual system efficiency of 47.3% and solar fraction of 0.57, was found to be the best-performing one, followed by S1, M0, and S0. System M1 also reduced the annual energy consumption of the backup heater in S0 by 16.45%. The thermostatic mixing valve reduced the thermocline thickness. The incorporation of both mixing valve and multiple ports delayed the startup of the heater, reduced the system's thermal losses, and slightly improved the collectors' efficiencies. The proposed tank model can be a viable tool for solar energy designers to optimize the number and relative positions of the inlet and outlet ports for maximized system efficiency and solar coverage.

Daily start-up is a typical feature of concentrated solar power plants (CSPs) due to solar energy intermittency. Therefore, appropriate start-up operation strategies are significant for CSPs. A parabolic trough concentrated solar power plant (PTCSP) with molten salt (MS) is a potential technical route. However, little attention has been paid to the dynamic start-up performance of PTCSP using MS. To mend the research gap, the dynamic start-up simulation of PTCSP using MS is conducted. Main contributions of this study are the dynamic start-up simulation of PTCSP using MS and evaluation of two MS anti-freezing solutions. Results indicate that the outlet MS temperature of solar field transiently exceeds nominal values during start-up processes. The inlet feedwater temperature of the preheater is much lower than MS freezing temperature during start-up processes. Therefore, two anti-freezing solutions were used to avoid MS solidification. Compared with utilizing the recirculating pump, utilizing the low-load regenerative heater can enhance anti-freezing performance, which could reduce the maximum control deviation of the preheater inlet feedwater temperature by 2.0 °C and increase the average outlet MS temperature of the preheater by 2.4 °C. This study may provide guidance for the dynamic simulation and operation optimization of CSPs during start-up processes.

To achieve national target proposed by the Renewable Energy Source Directive 2009/28/EC, to also accomplish to the CO2 emission reduction targets and to decrease the energy dependency Latvian government is planning to adopt different strategy policies such as feed-in tariffs (FITs) and capital subsidies, in order to incentive investor to use renewable based technology for power production Neverthelss it is crucial to understand in long term perspective the effect and the costs of a specific policy (made even by the combination of different policy tools) applied to the energy sector. Using this model, or an extended version of it, a cost/benefit analysis of a different set of policy scenarios can be carried out. More in specific this study is driving its attention at a situation where it is possible to increase the share of wind power in the energy balance respect the use of natural gas as primary energy for power generation. Four political instruments are chosen in this model: subsidies for construction of new wind-power facilities, information package at all power supply levels for risk reduction and reduction of maintenance costs through a learning effect. The simulation period is from 2010 to 2110. The analysis of policy instruments for development of renewable energy resources in power system illustrates wide potential of system dynamic modelling use for statement of priorities on power diversification. The policy instrument of use of subsidies is a crucial priority. Feed-in tariff is not providing an evident. The reason of that can be related to the key aspect on the way Latvia is organizing its feed-in tariff policy.

Intensified interaction between electric power system (EPS) and district heating network (DHN) has raised an urgent requirement of security control to ensure the regular operation of the heat and electricity integrated energy system (HE-IES). However, the implicit expressions of thermal dynamics remain an obstacle to building the quantitative relationships between the EPS and the DHN. To solve this, this paper proposes a novel dynamic model of the district heating network, which contains the equivalent pipe model and the analytical thermal source-load function (TSLF). Then, the interaction between EPS and DHN is divided into the energy flow calculation at the control points and the dynamic simulation during the control intervals to investigate the coupling effect. On this basis, the dynamic characteristics in HE-IES are employed to quantitatively establish the security control strategy using the combined sensitivity analysis. Case studies verify the accuracy and efficiency of the proposed method.

The variation and uncertainty of renewable energy potentially impact power system stability. This article proposes an efficient uncertainty evaluation algorithm to evaluate the influence of renewable energy uncertainty on power system dynamic performance. This algorithm applies probabilistic collocation method (PCM), which greatly reduces the simulation burden without compromising the result accuracy, to approximate the dynamic simulation results. The proposed algorithm also considers the correlation among adjacent renewable generators by using the Copula function, which is suitable to model nonlinear correlations. Additionally, this article extends the utilization of PCM. The actual historical data of renewable generation productions can be utilized directly, and kernel density estimation (KDE) is used to capture the nonparametric distribution of renewable generation production. To improve the accuracy of the approximation results, the proposed method adopts K-means clustering technique to select the approximation samples of input variables. The proposed probabilistic dynamic simulation algorithm is compared with Monte Carlo simulations (MCS) with the probabilistic results on the IEEE 39-bus system with multiple renewable generators, and the accuracy and efficiency of the proposed algorithm are validated.

An explicit dynamic simulation of the vertical crash of a regional airliner’s middle fuselage section has been conducted to investigate its crashworthiness. The simulation result shows that there a...

A hybrid photovoltaic thermal (PVT) panel is a module in which the photovoltaic (PV) layer is not only producing electricity, but also operates as a thermal absorber. As a result, thermal and electrical energy are being produced simultaneously, operating as a micro-cogeneration equipment. As in any cogeneration system, there is tight link between the electrical and thermal performance and it is dependent on multiple parameters: climate conditions, thermo-physical, geometrical and electrical properties. This paper investigates the effect of the variation of several of these parameters on the electrical and thermal performance, as well as on the global output. In order to achieve this, a dynamic numerical model is proposed, which simulates the heat exchange between the layers of the PVT panel. The model was applied to two different climatic conditions: Bucharest, Romania and Strasbourg, France, in order to assess and compare their behavior and performance. The simulation computes the temperature of each layer at any particular time, and a slightly higher outlet temperature of the working fluid can be observed in Bucharest during the summer, and in Strasbourg during the winter. The model is validated against data from the literature and can be applied to any climatic conditions and adapted for multiple geometrical and thermo-physical configuration. Next, a one-factor-at-a-time parametric analysis is carried out in order to assess the impact of various parameters on the electrical, thermal and global efficiency. The results showed in most cases a compromise between the electrical and thermal performance: in terms of wind speed and insulation, the thermal benefits of low wind and high insulation overcome the decrease in electrical efficiency. The packing factor was found to be optimum when maximized, as the electrical benefits are more significant than the thermal loss. The width of the channels in the heat exchanger should also be maximized as far as technologically possible for best performance.

The effects of different human walking patterns on contaminant dispersion in residential kitchens were investigated through computational fluid dynamics simulation with the dynamic mesh method. A tracer gas experiment was performed to verify the feasibility and accuracy of the simulation method. Flow characteristics induced by human walking were minutely described, and the transient capture efficiency of the range hood was adopted to assess the impact of human walking quantitatively. Human walking parallel to a counter, human walking parallel to a counter manned by another human, and human walking toward a counter were studied. Results showed that the mutual effect of the wake and thermal plume caused contaminant dispersion and decreased the performance of the range hood as the human subject walked beside the counter. Even a standing person operated ahead the counter, the wake would affect the thermal plume in a certain extent. The decrement of capture efficiency approached 0.5 in the most unfavorable situation. Moreover, the coaction of the positive/negative pressure zone and impinging air jet drew the thermal plume to the human body. The fluctuation of capture efficiency in this condition was moderate relative to that for the human walking pattern beside the counter. This research could provide a comprehensive overview of different human walking patterns and their impact on residential kitchens and thereby facilitate the maintenance of kitchen air quality.

Readily available processing hardware and "off-the-shelf" (OTS) simulation software has made "high fidelity" first principles models of both steady and transient states, for both axial and centrifugal industrial compressors, relatively easy to construct. These high-fidelity models are finding their way into "real-time. digital twin" performance monitors, front-end engineering design, and post-design – pre-construction compressor performance evaluation. The compressor models are useful for reliably demonstrating the compressor and – to some degree, based on the complexity of the model – process response to various operating conditions. Once the model is constructed, it is trivial to run a "what-if" analysis of compressor performance to answer questions related to (a) recommendations or validation of the recycle/vent valve size and actuation speed, (b) general piping layout and sizing around the compressor, (c) and hot gas bypass requirements, to name a few. This paper takes a practical approach in discussing the compressor and process parameters necessary for building these dynamic "high-fidelity" industrial-compressor models. We identify compressor inputs and compressor responses that are faithfully modeled by first-principle equations available in the simulation software and those that typically require a compromise between an "ab initio" and data-fitting approximation. We discuss the simulation's tendency to overstate pressure excursions during surge events and understate the compressor operation in the "stonewall" region. We also discuss using the simulator software's compressor-stage enthalpy calculations to predict and quantify the compressor train reverse rotation. We use our broad experience and understanding of the compressor operation and simulation and our experience with the AVEVA™ Dynamic-Simulation "OTS" simulation software as the basis for this discussion.

Gear tooth profile deviations are usually inevitable due to the application of intentional tooth profile modification, the existence of undesired gear manufacturing errors and the tooth surface defects during operation, and they have been demonstrated to have significant effect on the vibration and noise level of gear transmissions. How to calculate the gear mesh forces accurately is crucial for gear dynamic simulation, especially in the presence of gear tooth profile deviations that will complicate the interactions at the gear mesh interface. This paper presents a spur gear dynamic model where the detailed deformations of individual teeth are considered, including the tooth flexible deformations, gear body deformations, the local teeth contact deflections, and the tooth deformations due to its neighboring loaded tooth. This dynamic model is validated by experimental test results with and without tooth tip reliefs. Then, the optimization of the tooth tip relief is performed. Finally, it is compared with three traditional dynamic models to reveal their discrepancies and applicability which could supply theoretical guidance for selection of gear dynamic models.

The transparent elements of the building envelope have a crucial role not only in term of heat and mass transfers control, but also for natural light penetration, sound insulation, thermal and visual comfort of the occupants and their health. Among passive technologies, the light shelves could be architectural solutions for improving daylight penetration and for controlling thermal loads. The available research papers usually focus on one aspect. For this reason, the aim of the present study is to analyse the application of the light shelves with multidisciplinary approach and thus, taking into account: daylight, electricity for lighting, cooling and heating needs and thermo-hygrometric comfort. The case study is a real dormitory building placed in Athens and subject to a deep energy renovation toward the nearly zero energy building target. EnergyPlus, by means of DesignBuilder interface, has been used as dynamic simulation tool. Among ten different configurations, the optimal one turns out to be the internal horizontal light shelf placed at 50 cm from the top of the window with a depth of 90 cm or 60 cm. It has been found that in some cases the reduction of electricity for lighting cannot balance the variation in heating and cooling needs.

The objective of this paper is to perform an in-depth feasibility analysis and dimensioning of a potential Environmental Control and Life Support System (ECLSS) and power system for a crewed lunar base at the lunar south pole. The analyzed ECLSS includes an In-Situ Resource Utilization (ISRU) reactor for oxygen resupply and a Regenerative Fuel Cell System (RFCS) as power supply during shadow phases. The co-dependencies and interactions between the ECLSS sub-systems themselves and with the environment are incorporated to achieve a holistic system analysis. We used a fixed ECLSS configuration based on the current NASA plans for a Moon base ECLSS with a fixed function-to-subsystem allocation. The performed trade-offs are then restricted within the design space, to e.g. resize tanks and individual subsystems instead of considering other possible subsystems. We chose this approach because the aim of this paper is to perform an in-depth system analysis of all related subsystems and their interaction with the environment instead of a top-level trade-off. The first step is the selection of a suitable landing site and the dynamic simulation of its lighting conditions over the investigated period of 1 year. We use a slope map with a resolution of 120 m per pixel, a Permanently Shaded Region (PSR) map with a resolution of 240 m per pixel and a digital elevation model with a resolution of 240 m per point, which is interpolated from a source with a resolution of 60 m per pixel and meshed with triangles by the Thermal Moon Simulator (TherMoS) tool in order to calculate illumination values. The requirements chosen for the candidate landing sites are a slope of less than 5° over a diameter of at least 1 km and having both a PSR and a Peak of Light (POL) in less than 10 km distance. We discuss the four most promising candidate sites in this paper and calculate initial energy storage system estimates to select two landing sites for further analysis. We derive a reaction kinetics model for the ilmenite hydrogen reduction ISRU process from literature data and incorporate it into a dynamic model with simulated lighting and thermal conditions to calculate heat losses to the environment and the required electrical energy for its operation. In addition, we use the derived model to analyze and compare different design options of the ISRU reactor with an Equivalent System Mass (ESM) based optimization approach to identify the optimal operating conditions. Using this approach, we found operating temperatures above 1150 K resulted in higher ESM values for the reactor than lower temperatures. For the Moon base, we combine an ISS ECLSS model and the ISRU reactor model. The state-of-the-art urine and water processing technologies achieve recovery rates of up to 98%. Hence, we expect the overall ECLSS including the ISRU reactor to have a water surplus when combined with a Sabatier reactor to process metabolic CO2 from the crew into methane and water. Therefore, the Sabatier reactor combined with an electrolyzer can potentially generate methane and oxygen as fuel for resupply missions. The system can achieve a theoretic fuel production of 4100 kg per year using this approach. Although the dynamic analysis showed that only 2588 kg could be produced per year because of the lean operating conditions of the Sabatier and its efficiency of below 100%. The produced oxygen and methane could reduce operating costs for the base by reducing the required fuel resupply. Based on the power demands of the other subsystems and the available solar power and shadow duration at the selected landing site, we dimensioned the RFCS and estimate the required mass for it to 19,500 kg. Which is less than half the mass required if lithium batteries are used. The overall system requires resupply of approximately 6580 kg per year for a crew of six. The dynamic analysis of the system showed that the initial mostly steady state sizing approach can be optimized and relevant system parameters can be reduced by more than 15%.

A numerical model has been developed to investigate the dynamic characteristics of the Superconducting electrodynamic suspension (EDS) system. Modeling of the guideway with the surface irregularity and the Maglev vehicle are described. Numerical simulations were performed in Simulink to solve the coupled problem. A 3-D model of the electromagnetic system of the superconducting EDS train is established, and the computed real electromagnetic forces are coupled with the maglev train. The EDS train was simulated by using the SIMPACK multi-body dynamic program. The simulation was carried out by using two body models of rigid and flexible bodies. In order to use the modal information to construct the flexible car body, the finite element method and the ABAQUS software were used to construct it together with equivalent elements. The final framework is constructed in MATLAB/Simulink to simulate dynamics and electromagnetic forces together with the constructed simulation framework. In order to consider the interference caused by irregularities, randomness and power spectral density (PSD) are used to analyze vibration interactions. We compared random signal inputs with PSD, greatly enhancing accuracy, and analyzed the vibrational interaction between car body and ride quality.

A nonlinear dynamic model considering the effect of heat transfer on outlet pulverized coal mass flow is established based on the principles of conservation laws. Raw coal moisture estimation which is connected to coal mass and internal energy in coal mills is included in the model. The model has proved to have good predictions and reflects the dynamics of the coal mill by verifications on historical data and dynamic simulation tests. Results show that the mean absolute error of mill differential pressure, mill electric current and outlet primary air temperature are 3.08%, 3.05% and 0.05% on validation operation data, respectively. The predictions fit the curves of the measured data that cover the whole operation of coal mill from starting up to shutting down.

The review aims to present a classification and applicability analysis of methods for preliminary molecular modelling for targeted organic, catalytic and biocatalytic synthesis. The following three main approaches are considered as a primary classification of the methods: modelling of the target – ligand coordination without structural information on both the target and the resulting complex; calculations based on experimentally obtained structural information about the target; and dynamic simulation of the target – ligand complex and the reaction mechanism with calculation of the free energy of the reaction. The review is meant for synthetic chemists to be used as a guide for building an algorithm for preliminary modelling and synthesis of structures with specified properties. The bibliography includes 353 references.

A novel coupling system that combines a photovoltaic/thermal (PV/T) subsystem and an Organic Rankine Cycle (ORC) driven by solar parabolic trough collector (PTC) is presented in this paper. The mathematical model is initially built. On the basis, the influence of area ratio of two collectors (PV/T and PTC) on the performance of system is discussed. The results show that the optimal area ratio of PV/T to PTC is 8:2, which can achieve the maximum energy output. Moreover, the performance of the coupling system and two independent systems (PV/T and ORC system) are compared and analyzed. The results show that the coupling system is more reliable and its total output energy (heat and electricity) is the highest, compared with the other two independent systems. The solar energy utilization efficiency of the coupling system is 40% higher than that of the other two independent systems in the steady-state simulation. Moreover, the annual output energy per unit area collector of the coupling system is 13% higher than that of the other two independent systems in the dynamic simulation. Furthermore, in the dynamic simulation of a typical day, the PV panels’ temperature of the coupling system is 5°C–7°C lower than that of the independent PV/T system. It means that the power generation efficiency of PV panels can be increased by 1.5%–3.5%. This study aims to explore the operation characteristics of the novel solar energy utilization coupling system and promote the development of renewable energy utilization models, which provides a reference for the design and optimization of related energy systems.

In the drilling process of difficult-to-cut materials, conventional drilling has resulted in various problems such as high drilling temperature and poor machining quality. Low-frequency vibration-assisted drilling has great potential in overcoming these problems since broken chips are generated. In order to promote the application of low-frequency vibration-assisted drilling device in machining difficult-to-cut materials. In this paper, a low-frequency vibration-assisted drilling device is developed by using a novel ring flexure hinge as the elastic recovery mechanism. First, based on the theory of elastic mechanics and mechanical vibration, the stiffness of the ring flexure hinge is designed theoretically, and the influence of its structural parameters on its deflection is analyzed. And then the correctness of the theoretical design is further verified by static and dynamic simulation and stiffness test. Finally, the vibration performance of the device is tested under no-load condition, and the actual drilling test is conducted to verify the drilling performance. The results show that the device could realize the axial low-frequency vibration with constant frequency-to-rotation ratio and amplitude stepless adjustment and present good working stability under no-load and load conditions. In the actual drilling test of titanium alloy and carbon fiber reinforced plastic (CFRP)/ titanium alloy laminated structure, the device under appropriate processing parameters breaks the titanium alloy chip into small pieces and reduces the drilling temperature by 44% and inhibits the secondary damage of CFRP. It is demonstrated that the device could meet the actual processing requirements. And it also provides guidance for the design of low-frequency vibration-assisted drilling device.

In order to comprehensively consider the dynamic behavior of vehicle system and the contact forces between wheel and rail, the vehicle-track coupling model is established considering the flexible wheelset and rail modal characteristics. Guyan reduction theory is introduced to reduce the degrees of freedom of wheelset and rail and to improve the calculation speed. Due to small axle load variation of freight wagon operating on the special line for the coal transportation, the vehicles with different speeds and wheel flat lengths, whether in empty or loaded conditions, are simulated and then the mapping relations between the flat lengths and wheel/rail impact force are obtained. Subsequently, the fitting functions for the empty and loaded vehicles are fitted to quantitatively detect the wheel flat by trackside equipment. The results indicate that the fitting function of empty vehicle has a better effect on predicting the flat length within 6% error since wheel/rail contact force of empty vehicle induced by wheel flat increases with the increase of flat length, while that of loaded vehicle presents a parabola variation trend at low speed and increasing trend at higher speed.

This work illustrates the results achieved by ongoing collaboration between the Uffizi Gallery and the University of Florence. This collaboration has focused on the New Uffizi Project and sought to evaluate the energy consumption of the HVAC systems of the Vasari Corridor by applying the typical tools and methods for the Building Energy Model (BEM) of existing buildings. In order to perform a dynamic simulation of the energy behavior and thermal comfort of the Corridor, the Building Energy Model was validated by comparing the hourly measured and simulated indoor temperature values and through the varying of natural ventilation and solar shading. Due to its building characteristics the control of the indoor thermo-hygrometric parameters is a critical issue. These aspects expose the Corridor to climatic variations which necessitate major energy consumption. In estimating energy consumption, three different scenarios of the use of the Corridor itself were referenced: one of which was its return to the original Medici use as a connection between Palazzo Pitti and Palazzo Vecchio through the Uffizi Galleries;the other two were the possible uses for temporary exhibitions of artwork which met the acceptable parameters of indoor air quality (thermal comfort and control of risk of SARS-CoV 2).

This study aims to investigate the mixing time of the side-entry mixer tank and the influence of the propeller's rotational speed on mixing time by the Computational Fluid Dynamic (CFD) method. The tank's model is a flat-bottom cylinder tank whose diameter is 40 cm with a 6 cm propeller contains three blades. The tracer, HCL 37%, was injected on the water's surface while the propeller's rotation speed is varied 100 rpm, 200 rpm, 300 rpm, and 400 rpm. The simulation process is examined using CFD FLUENT 17.1, with a turbulence model is k-ɛ RNG. Its conditions are single-phase then proceeded using species transport. Furthermore, the monitoring point's simulation is identical to the experimental data monitoring probe, which is used to inspect the mass fraction at each point. After all, this simulation contains three processes: pre-processing, solving, and post-processing. as a result, the propeller's higher rotational speed makes the mixing time shorter in the CFD method, which has a good agreement with the experimental method. Moreover, this study also examines the impact of the grid's type and the geometric size for the mixing process in the side-entry mixer tank.

Transmission of natural gas from its sources to end users in various geographical locations is carried out mostly by natural gas transmission pipeline networks (NGTNs). Effective design and operation of NGTNs requires insights into their steady-state and, particularly, dynamic behavior. This, in turn, calls for efficient computer-aided approaches furnished with accurate mathematical models. The conventional mathematical methods for the dynamic simulation of NGTNs are computationally intensive. In this paper, the use of autoregressive neural networks for cost-effective dynamic simulation of NGTNs is proposed. Considering the length, diameter, roughness, and elevation as the main characteristics of a single pipeline, a neural network pipeline (NNPL) is designed and trained based on the data from a dynamic process simulator. Arbitrary NGTNs can then be easily constructed by connecting the developed NNPLs as the building blocks. The performance of the NNPL network is demonstrated through a number of benchmark pipeline systems, where a very good agreement with the benchmark results is found.

A solid oxide cell-based energy system is proposed for a solar-powered stand-alone building. The system is comprised of a 5 kWel solid oxide fuel cell (SOFC), a 9.5 kWel solid oxide electrolysis cell (SOEC), and the required balance of plant. The SOFC supplies: 1- building demand in the absence of sufficient solar power, 2- heat for SOEC in endothermic and standby modes. Thermal integration of SOFC and SOEC is implemented through a network of heat exchangers, combined with set of control algorithms. Two control strategies were implemented to actuate the SOFC in response to endothermic heat demands of SOEC by manipulating: 1- electric power, 2- fuel utilization. The results of dynamic simulation of system for two scenarios (sunny day and cloudy day) showed successful compliance of temperature constraints with both methods. Manipulation of fuel utilization, however, resulted in better system performance in terms of efficiency and H2 balance.

Numerical simulation is the key technique for large-scale power system analysis. Redistribution of global renewable power via international interconnections requires new simulation tools to study the interconnected systems with different nominal frequencies as a whole. This paper introduces an open-source simulation toolkit for electrical power systems (STEPS) hosted at Github. Its kernel is coded in C++ with major functions of power flow and electro-mechanical dynamic simulation. Flexible options are provided and configurable to improve power flow solution and dynamic simulation. Common devices and models are supported in STEPS for AC/DC hybrid system studies. The study of interconnected systems with different nominal frequencies is supported in STEPS for research of international interconnection. Application program interfaces are provided and wrapped with Python to enable high-level interfaces for general applications. STEPS is thread-safe, and parallel computation is supported in both kernel-level and task-level parallelization to accelerate simulation. It is portable and works on Windows and GNU/Linux platforms. Cases from small to large-scale systems are thoroughly tested to validate the toolkit with commercial packages as benchmarks.

The paper presents a method of determining the dynamic parameters of multiple-rocket-launcher system mounted on the wheeled vehicle based on Newton's law of motion. The dynamic simulation was conducted and then the results were compared with the corre-sponding experimental data to verify the reliability of the model. The model was ap-plied in calculation and tested out on multiple-rocket-launcher system B?-21 (of Rus-sia). The theoretical model calculation results are relatively consistent with the meas-ured experimental data. The dependence of the launcher oscillation on the rate of fire was investigated, which determined the optimal rate of fire for each launcher. These results are used to evaluate the firing stability of the launcher when firing individual shots and firing bursts. This is an important theoretical basis which can be a reference for designers in the design process of improvement, manufacture, exploitation and use of a launcher mounted on the wheeled vehicle.

In order to more accurately analyze the dynamic characteristics of the working device of the hydraulic excavator. The load changes on the two digging trajectories were calculated and analyzed by using the limit digging force model and the theoretical digging force model, respectively. The rigid-flexible coupling model of the working device was established in ADAMS. Taking the limit digging force (LDF) and the theoretical digging force (TDF) as the external load of the working device, the dynamic simulation of the hinge force of the working device in the two trajectories was carried out, and the structural strength analysis of the bucket was carried out by using ANSYS. The results show that the tangential force of the LDF is generally larger than that of the TDF, the hinge point force of the working device changes dynamically with the external load of the tooling, and the influence of the LDF on the hinge point force is greater than that of the TDF. When the LDF is taken as the external load, the structural strength of the bucket meets the operational requirements.

Prediction of the way wildfires propagate in forests and rangelands is one of the critical issues in environmental protection and disaster management. This research aims to simulate wildfire propagation using a geographical information system (GIS)-based cellular automata (CA) model. The model considers the most effective spatial and temporal drivers of wildfire propagation, including wind speed and direction, type and density of vegetation, and topographic conditions. Wind speed and direction were considered changeable over the simulation process. A genetic algorithm (GA) was used to calibrate the model developed. Validation of the model was performed using an independent fire case assessed by the overall accuracy (OA) criterion and the Kappa coefficient index. The mean values obtained for the OA and the Kappa coefficient in 100 runs for two wildfire cases indicated that the proposed model could be effectively used in the simulation of wildfire propagation. The results of this model can assist fire managers in predicting fire propagation to better control wildfires.

Train derailments in railway switches are becoming more and more common, which have caused serious casualties and economic losses. Most previous studies ignored the derailment mechanism when vehicles pass through the turnout. With this consideration, this work aims to research the 3D derailment coefficient limit and passing performance in turnouts through the quasi-static analysis and multi-body dynamic simulation. The proposed derailment criteria have considered the influence of creep force and wheelset yaw angle. Results show that there are two derailing stages in switch panel, which are climbing the switch rail and stock rail, respectively. The 3D derailment coefficient limit at the region of top width 5 mm to 20 mm is much lower than the main track rail, which shows that wheels are more likely to derail in this area. The curve radius before the switch rail is suggested to be set as 350 m. When the curve radius before turnout is 65 m, the length of the straight line between the curve and turnout needs to be larger than 3 m. This work can provide a good understanding of the derailment limit and give guidance to set safety criteria when vehicles pass through the turnout.

Zero-dimensional two-stage SOFC stacks dynamic model was developed to investigate the effect of operating parameters on stacks performance. The model resolves spatially thermal and thermo-electrochemical behaviour for electrochemical reactions, Catalytic Partial Oxidation and Steam Reforming processes. Design variables and thermo-electrochemical properties were obtained from in-house-fabricated SOFCs carried out by project partners. The completed SOFCs based Combined Heat and Power, CHP, system model was validated by data 18 and numerical results obtained at steady-state mode showing its high-fidelity. A parametric study with respect to key operating parameters including changes in fuel utilization, lambda number and current density values was conducted. The global CHP system dynamic response, in term of the current/voltage delivered by two-stage SOFC stacks, under a fixed fuel utilization, has been determined resulting in greater variations in the voltage of a single cell in the first stack in comparison to the corresponding values in the second stack.

In this article, we describe the use of dynamic simulation when designing an effective system for order picking within a distribution warehouse. The simulation model was created in the Witness software environment for discrete dynamic simulation and is a modification of a general simulation model of material flows in supplier systems. Using the example of a batch system for picking orders in a drugstore goods warehouse, we discuss the possibilities of using a general simulation model of material flows as an effective framework for the development of system support for warehouse processes using warehouse management system (WMS). The simulation model is based on the possibility of distributing any material flow in the supply system into a finite number of movements with the possibility of using one of the sources and fulfilment of certain conditions. In order to achieve the required optimisation of the order picking system, which depends, in particular, on the unknown duration of goods collection at the picking location, and on the duration of goods sorting in consolidation, the “what-if” analysis has been used as a tool to measure the impact of uncertainty of one or more variables entering the model on the uncertainty of output variables. The study showed that minimisation of the number of physical elements in the model leads to a significantly higher speed of its operation. By means of dynamic simulation, it is possible to test a large number of variants of the picking system layout in a relatively short time and minimise the risk of erroneous decisions associated with the implementation of a suitable WMS.

Extractive distillation is widely accepted and commercialized for separating azeotrope mixtures, but using traditional organic solvents leads to intrinsic obstacles such as the high energy requirement and solvent-related environmental problems. Benefiting from the development of green solvents, using ionic liquids instead of traditional solvents as entrainers for extractive distillation has attracted wide attention. This paper presents a multi-objective optimization strategy to integrate the design and control of the ionic liquid-based extractive distillation processes. In the optimization processes, the condition number (CN) and total annual cost (TAC) are minimized as the objective functions to evaluate the control properties and design of three different separation systems. The optimization results are shown by the Pareto front, which is based on trade-offs between controllability and economics. The environmental impact is evaluated by the environmental impact potential of energy for each system in a posterior stage during the optimization processes. Designs with minimum TAC (PT), trade-off designs between TAC and CN (PO) and designs with minimum CN (PC) on Pareto front are optimized and compared. The results show that the increase of reflux ratio can improve the control properties for the ionic liquid-based extractive distillation processes. Furthermore, the dynamic simulation of PT and PO are carried out to compare their dynamic responses based on the same dynamic control structure, and PO shows better performance in the aspects which include maximum deviation and residual error of dynamic response.

At present, nitrogen production from air by pressure swing adsorption (PSA) is simulated almost exclusively at low product purity levels (2). However, with increasing global demand for highly purified gases provided by energy-efficient separation processes the requirement for either extensive experimental research in the high-purity range or predictive computer simulations arises. This paper presents a mathematical model of a twin-bed PSA plant equipped with a carbon molecular sieve (Shirasagi MSC CT-350) for the generation of high-purity nitrogen (99.9–99.999% N2). The model is implemented in the process simulator Aspen Adsorption™. The influence of operating conditions as well as the cycle organisation on the process performance is validated, especially the influence of pressure, temperature, half-cycle time, purge flow rate, and cutting time. The precision of the performance prediction by numerical simulations is critically discussed. Based on the new insights efficiency improvement strategies with a focus on reduced energy consumption are introduced and discussed by means of radar charts.

Esse trabalho tem como objetivo estudar os parâmetros primordiais de uma máquina de relutância variável por meio do método analítico e uma simulação dinâmica com o auxílio do software MATLAB/SIMULINK. As respostas obtidas por meio destes dois métodos devem se apresentar muito próximas e exatas.