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Workload fluctuation is one of the challenges facing contracting organizations. Previous studies balanced this fluctuation using capacity adjustment. Most of these studies ignored the simultaneous effect between the direct and indirect variables and the nondeterministic nature of these variables. Moreover, local decisions, i.e. project-based decisions, receive the most attention from contractors. Contrarily, its long-term effect on the organization and its influence on the future project's success receives little attention. This study utilizes a system dynamics approach to holistically address the workload fluctuation of contracting organizations. The model links the pre-award and after-award project phases at the portfolio level. The model is validated through extreme case analysis, units' consistency test, sensitivity analysis test, and industry experts. Results from model analysis inform that the internal behavior and mental model (soft logic) are significantly affecting the long-term performance of contractors more than the external (hard) factors. For instance, the quality level is more important than the initial cash. Also, overhead and markup percent have a significant impact on long-term behavior. Overheads have a relatively more effect on short-term behavior than the markup percent. This research is limited to representing the contracting organization in the execution phase and could be enhanced in the future by incorporating other phases such as design. [ABSTRACT FROM AUTHOR]

The Covid-19 pandemic, a major global issue, has created a severe health emergency for the past year. In addition, it led to a crisis of governance and policies for handling Covid-19 worldwide, particularly in the city of Surabaya. The Surabaya city government has implemented various policies to handle the Covid-19 pandemic. However, there is no study to evaluate the effectiveness of those policies. This study aims to provide predictions and evaluations regarding the effectiveness of implementing policies for handling the Covid-19 pandemic in the City of Surabaya, especially the Covid-19 vaccination policy. Furthermore, we simulated the effect of those policies on the rate of infected people using the dynamic system model using Vensim PLE. The simulation results show that implementing of the Covid-19 vaccination policy has proven adequate to reduce the total number of infected by 13.25% and reduce the total number of deaths by 35.55%. Moreover, the implementation of vaccination, the enforcement of community activity restrictions (PPKM), convalescent plasma therapy, contact tracing and isolation, and also swab tests have been proven to reduce the rate of increase in Covid-19 cases effectively. [ABSTRACT FROM AUTHOR]

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]

Today, urban congestion is worsening in many countries as a result of population growth, economic growth, private car ownership, urbanization, housing development, and employment opportunities. It is very important to understand what factors cause this traffic congestion. Thus, this paper discussed on how travel demand strategies contribute to traffic congestion in Kuala Lumpur, Malaysia. Using a causal loop diagram (CLD), a hypothetical framework was developed to represent the causality of connected variables in four subsectors: transport demand, transport supply, transport system, and modal share in traffic congestion based on various reports from government agencies and existing literature reviews. A conceptual structure of CLD allows the modeler to understand the dynamic relationship between variables found in the complex transportation systems. The CLD will be used as a basis for developing a dynamic simulation model in future work. [ABSTRACT FROM AUTHOR]

The dilemma for any model-based controller is its process model's development effort and accuracy. Thus, selecting an appropriate modeling technique for the model-based controller is noteworthy to achieve the best control performance. In this work, a block-oriented modeling technique, namely the neural wiener (NW) model, is developed for the Ethylene Glycol (EG) plug flow hydrogenation reactor. The NW model consists of a linear block using state space (SS) model and a nonlinear element using a static neural network model. Presently, no prior research has been carried out previously using the NW model for EG production. The EG hydrogenation reactor is modeled using Aspen Plus for steady state and Aspen Dynamic for dynamic simulation. For modeling purposes, the selected process inputs are jacket flow rate and hydrogen feed flow rate. Meanwhile, the EG output mole fraction and product temperature are chosen for the process outputs. The performance of the developed NW model is evaluated using a validation dataset, and a state space (SS) model is used as a comparison. Based on the model validation results, the NW model has achieved R2 (coefficient of determination) of 0.97 compared to the SS model with R2 of 0.78 for Output 1(EG mole fraction). For Output 2 (Product temperature), the NW model has produced R2 of 0.94 in comparison with the SS model with R2 of 0.69. Thus, the NW model has outperformed the SS model in modeling the EG hydrogenation reactor. [ABSTRACT FROM AUTHOR]

The integration of high temperature thermal energy storages into existing conventional power plants can help to reduce the CO2 emissions of those plants and lead to lower capital expenditures for building energy storage systems, due to the use of synergy effects [1]. One possibility to implement that, is a molten salt storage system with a powerful power-to-heat unit. This paper presents two possible control concepts for the startup of the charging system of such a facility. The procedures are implemented in a detailed dynamic process model. The performance and safety regarding the film temperatures at heat transmitting surfaces are investigated in the process simulations. To improve the accuracy in predicting the film temperatures, CFD simulations of the electrical heater are carried out and the results are merged with the dynamic model. The results show that both investigated control concepts are safe regarding the temperature limits. The gradient controlled startup performed better than the temperature-controlled startup. Nevertheless, there are several uncertainties that need to be investigated further. [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]

SiO2 glass has been shock-melted at 100 GPa and then ramp compressed on the Z Accelerator at Sandia National Laboratories. In a shock-ramp experiment, a shockless ramp wave follows the shock impact, isentropically compressing the sample. This technique provides access to off-Hugoniot states, which are of importance to both materials and planetary sciences. Here we present results from shock-ramp experiments for two compositions of SiO2 glass, one with 1000 ppm by weight and one with <1ppm OH. We observe an increased particle velocity at the window-interface for SiO2 melt with 1000 ppm OH relative to the anhydrous sample, suggesting higher sound speed for the hydrous silicate melt. We describe how the lower shock impedance of molten silicate relative to the LiF window precludes the usual approach of iterative Lagrangian analysis to extract compressibility from shock-ramp velocity measurements. To understand the observation of higher velocity for the hydrated sample, and to guide development of a new shock-ramp data analysis approach, we present results from LAMMPS molecular dynamic simulations for SiO2 with 0-1wt.% H2O. These simulations show that the incorporation of water into SiO2 melt decreases the compressibility at constant pressure, consistent with the experimental observation of a stiffer response for the hydrated SiO2 melt. [ABSTRACT FROM AUTHOR]

Understanding the path through thermodynamic space that a high explosive experiences during shock to detonation transition (SDT), detonation propagation and failure are important for understanding the roles of these experiments for reactive flow model calibration. SDT, steady detonation propagation, corner turning (ECOT), multi-shock, isothermal and isentropic compression, shock release and re-shock, GapStick and other experiments may "overlap" with respect to the thermodynamic states attained. The focus of this study is to explore a methodology to examine where the reactants equation of state are taken by experiments. To that end, clearly a complete reactive flow model is needed to faithfully ascertain the dynamics of each experiment. For this exploration, an Arrhenius-Wescott-Stewart-Davis (AWSD) model is utilized for dynamic simulations of the tri-amino-tri-nitro-benzene (TATB) based plastic bonded explosive PBX 9502. Here, only an example of SDT will be given, as it serves as a validation of the more general methodology. [ABSTRACT FROM AUTHOR]

Manipulator Robot is a robot shaped like a human arm. This robot has been widely developed, and used in various sectors such as industry, medical, and military. One of the most popular applications of manipulator robots in industrial fields is sorting. Sorting is the activity of separating very many objects to be placed in the appropriate place. Often when sorting, the objects that are lifted have different loads. Therefore, we need a control that can move the manipulator robot remain stable without producing a large error. This proposal discusses the design of a dynamic simulation of a 6 DoF manipulator robot into a small-scale model of an industrial robot. Simulation is used to save costs and avoid component damage during testing. Robot modeling is formed using the features of ROS, namely URDF (Unified Robot Description Format), which will then be displayed in the Gazebo application. PID controller is used to control each joint on the robot so that the robot remains stable when moving. In this study, testing will be carried out by means of the robot will lift several loads with different weights. A node will display the result of the angle error from each joint in the robot on the ros, namely rqt_plot. [ABSTRACT FROM AUTHOR]

The relevance of research is driven by the need to expand the possibilities of an explosion action controlling to obtain a rational rock mass fragmentation, the requirements to improve the safety of mining working, as well as the economic feasibility of reducing the loss of minerals and eliminating negative environmental factors of blasting. The paper presents some regularities of the radial air gap value influence for the TNT and ANFO charges on the yield of fractions during geo-environment explosive failure. The investigation were carried out experimentally on compositional models and numerically by the Smoothed Particle Hydrodynamics method (SPH). The article considers the methodological issues of combined application of compositional axisymmetric models and computer simulation for dynamic loading problems solving of the massive to identify patterns of stress localization and rock fragmentation. The research results made it possible to determine the dependences of the change in the middle rock piece and the yield of fines on the radial air gap value. In addition, the influence of the distance to the charge on the yield of the middle rock piece at different explosive densities was established. The developed research methodology makes it possible to determine numerically the influence of various factors on the nature of stress localization and to identify the trigger effect of the geo-environment explosive failure. The results comparison of processing physical experiments and computer simulation shows that the chosen approach ensures the reliability of the research results and turned out to be very useful for analyzing and better understanding the rock massive explosive failure mechanics. The results comparison for physical experiments processing and computer simulation shows that the chosen approach ensures the reliability of the research results and turned out to be very useful for analyzing and better understanding the rock massive explosive failure mechanics. [ABSTRACT FROM AUTHOR]

The deformation of polycrystal grains is hampered by the action of nearby grains. Their influence on structural changes under uniaxial compression has been studied using molecular dynamics simulations. [100] single crystals were studied as a characteristic orientation of growth grains. This orientation is most found in products obtained by electron-beam surfacing of aluminum bronze. The patterns of slip, twinning, and the formation of deformation domains are traced depending on the conditions for limiting the shear towards the lateral faces of the sample. Shown, that the shear limitation and the complication of the stress tensor contribute to the earlier development of twinning. [ABSTRACT FROM AUTHOR]

This paper focuses on the sorption hysteresis of spruce wood (Picea Abies). First, its hysteretic behaviour was measured under laboratory conditions at a constant temperature in several steps covering the entire hygroscopic range. The measurement had the form of loops with the same relative humidity at the beginning and end of each step. Then two hysteresis models, the independent domain theory based IPM model and empirical Frandsen's model, were successfully fitted to the measured data. To do so, modifications to their shape parameters have been proposed. Only a minor change was necessary in the case of the IPM model, more extensive in the case of Frandsen's model. Testing and application in dynamic simulation showed that the IPM model is able to capture more accurately and reliably the hysteretic behaviour of spruce wood. The use of the Frandsen's model should be preceded by a critical analysis due to the risk of pumping error. [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]

In any chemical process industry, the implementation of flare system involves a significant amount of investment in terms of capital cost. There is a significant opportunity to optimize the flare design by applying High-Integrity Protection System (HIPS). HIPS has been widely used as one of mitigation strategies in reducing the flare capacity for new and existing plant as this being allowed by API Std 521. For a new refinery complex, HIPS was introduced in a total of five (5) column reboilers in order to safely reduce the acid gas flare design capacity. Based on preliminary analysis, partial power failure scenario had been identified as the governing scenario for the acid gas flare design capacity. In this use case, HIPS will mitigate any potential overpressure scenario by cutting off the steam supply to the distillation column reboilers. However, it is important to consider the transient relief from the columns to the acid gas flare system considering this may affect the design capacity of the flare. The total transient relief rate estimated from dynamic simulation accounts for the amount of vapor generated due to residual heat from the reboiler after HIPS valves were closed and loss of reflux to the distillation column. The outcome of the model were time-series plots, detailing out the individual and total relieves of all the distillation columns. This paper presents a case study on relief load calculation with HIPS installation and consideration of transient effect for five columns before activation of HIPS together. [ABSTRACT FROM AUTHOR]

The issue of maintenance and rehabilitation of historical buildings in Slovakia and in the world is nothing special or unusual. Rather, the method and, above all, the effectiveness of routine maintenance, which should keep the historic building in good structural and technical condition, becomes problematic. The vast majority of historical buildings are not insulated by modern standards. In addition, in relatively small quantities, they are equipped with any vapor barrier layer, and therefore their perimeter structures allow the transport of water in liquid form, which allows both rainwater and ground moisture to penetrate into the interior. When trying to increase the interior temperature, increase the overall functional use of historical buildings and reduce the energy consumption of these buildings, thermal insulation from the interior can be a suitable solution. The paper deals with the energy efficiency of historic buildings in the form of internal insulation, where the impact of wood-fiberboard on the thermal and moisture regime of the perimeter wall of a historic building in Košice is assessed using dynamic simulations. [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]

The problem of mechanical wear in cement mills is one of the main problems in the cement industry, which costs cement manufacturers a lot of money. In this paper a modeling of the abrasion uncoated and coated lining by tungsten carbide nanoparticles of the cement mill in Kufa cement factory. This study was carried out using the DEM program for estimating the wear rate with fix the recent external effective normal and tangential forces and energies. The results showed that there are clear improvements in the wear resistance of the lining after the coating process, where the improvement rate in the abrasion rate reached 79%. [ABSTRACT FROM AUTHOR]

The article presents the results of mathematical simulation that deals with the impact of wheelset defects on the defect development according to Figures 10.1-2, 11.1-2, 30.1-2, 31.1-2 and 21.1-2, which leads to the removal of highly defective rails from the railway track structure. The presented assessment method of the dynamic behavior of the welded rail segment allows to evaluate the presence of defective wheelsets with flat spots or rail defects, located on the rolling surface. Dynamic contact simulation was carried out with the use of the equation, describing natural vibrations of the transversally isotropic plate-strip, two edges of which are rigidly pinched, the other two edges are pivotally supported, and the lower edge lies on a deformable roadbed. As a result, the maximum stresses, generated in the contact zone between the wheel and the rail, were determined, in terms of the presence of the wheelset defect. The data, obtained with the help of force criteria for the assessment of wheel roughness, can be used in the diagnostic systems of the wheelset technical condition. [ABSTRACT FROM AUTHOR]

Nowadays, screw press technology is more advanced due to a demand by oil palm industry to produce high oil production for consumer daily activity. The objective is to analyze the single and twin worm screw press by comparing several designs to maximize their lifespan of the worm screw press. This study used visual inspection, model development and simulation of worm screw press by using SolidWorks and calculation of design properties. Simulating a single tapered shaft and uniform pitch worm screw press with static and dynamic simulation resulted in the total life span yield of 4085 hours and 3621 hours, respectively. Meanwhile, simulating twin tapered shaft and uniform pitch worm screw press with static and dynamic analysis yielded the total life span of 3262 hours and 1685 hours, respectively. The option for the tapered shaft of screw press or uniform pitch was to be able to lessen the maintenance cost and further lifespan of the screw press. [ABSTRACT FROM AUTHOR]

The purpose of this study was to simulate Nickel oxide (NiO) and water (H2O) molecules, by observing their molecular characteristics and dynamics in the form of essential parameters, such as kinetic, potential and total energy, including its effect on the division of H2O into hydrogen gas molecules (H2).Simulations were carried out by modeling the molecular structures using Hyperchem Professional Release 8.0 and ChemDraw Ultra program, such as the 2-dimensional analysis with ChemDraw Ultra and 3-dimensional projections made using ChemBio. The molecular dynamics between (NiO) and Water (H2O) molecules were carried out using the Hyperchem program and 3-dimensional visualization displays. The molecular structure of NiO and H2O, as potential and kinetic energy increases, makes the H2O molecules to become unstable which leads to the splitting of the H-atomic body. The results showed that display energy significantly decreased for some time, due to the breakdown of molecular bonds facilitated by the increase in kinetic energy. Therefore, a high kinetic energy, leads to an increase in molecular movement. Furthermore, the maximum total energy versustime on H2O with and without NiO was 7.3kcal/mol and 4.55kcal/mol, respectively at 0.1 pswas obtained. Principally, important parameters, such as kinetic, potential and total energy, including temperature, time and its effect on the division of H2O into hydrogen (H2) molecules between a molecule of nickel oxide and water, indicate a high usability of nickel oxide in the catalytic form. [ABSTRACT FROM AUTHOR]

In the present study, molecular dynamic simulations of high-velocity impact of 3C-SiC nanorod in a wide range of velocities with a rigid wall, were performed. The influence of different types of artificial defects in the nanorod on the ability to accumulate impact energy was investigated. [ABSTRACT FROM AUTHOR]

This paper studies the influence of the structural elements on the output electrical parameters of a linear generator with permanent translational and rotating magnets in its stator windings. Dynamic mode simulations with ANSYS R19.1 have been presented, as well as results from experimental studies of a linear generator with rotating stator magnets. Six types of translational magnets have been studied and the optimal variant, in which the output electrical parameters of the generator significantly improve, has been determined. A model has been developed that adequately simulates the operation of the linear generator. [ABSTRACT FROM AUTHOR]

Molecular modeling has increasingly been used to investigate the structural dynamics, properties, and thermodynamics of biological systems. This study aims to evaluate the structural dynamics of gene-translated lipase structure from PLS 80, a novel bacterium previously isolated from undersea fumaroles, subjected to various temperatures. Prediction using SWISS-MODEL showed PLS 80 lipase had the highest homology (97,7%) with lipase 2DSN. The pair of PLS 80 lipase – 2DSN had the highest Global Model Quality Estimation (GMQE) and Qualitative Model Energy Analysis (QMEAN) values of 0.99 and 0.7, respectively. The lipase 2DSN was then used as the template. The temperature variation simulation was conducted using Assisted Model Building with Energy Refinement (AMBER) software at 300, 350, and 400 K for 50 ns. The parameters used for evaluation were Root Mean Square Deviation (RMSD), Root Mean Square Fluctuation (RMSF), the gyration radii (Rg), total energy, number of hydrogen bonds, and Solvent Accessible Surface Area (SASA). Although produced by a thermophile, the molecular dynamic simulation showed that the lipase had the lowest RMSD, Rg, and total energy when at 300 K. Higher temperatures increased the Rg and reduced the number of hydrogen bonds in the molecule. The RMSF values indicated that some residues were conformationally less rigid than other residues in the structure. The difference in RMSF values of some residues was significant when the temperature was increased, but not necessarily those with high RMSF values. The SASA values increased slightly when the temperature was alleviated by 100 K. However, the polar SASA value at 350 K was the lowest than the other temperatures. Visual evaluation of the lipase structure indicated that the b-sheet only shifted slightly at various temperatures. However, conformational changes were observed in the a-helix and turn/loop. At 350 K, the lipase had an additional b-sheet, while some turn/loop structures frayed to coil structures. These structural differences may explain the optimum lipase activity at around thermophilic temperature. [ABSTRACT FROM AUTHOR]

The delivery of peptide-type drugs to the brain can be passed by the BBB (blood-brain barrier) via the paracellular route. In this pathway, a barrier protein only passes molecules with a size of <11 Å and a molecular mass of <500 Daltons. Epithelium Cadherin is one of the barrier proteins in the pathway. The difficulty of entering the molecule is due to the interaction of E-cadherin...E-cadherin. It has been observed that in the E-Cadherin..ADTC5 complex there is an interaction between the amino acid E-cadherin (Phe35, Tyr36, Phe51, Ile52, Arg55, Val48) with the amino acid ADTC5 (Ace0, Cys1, Pro4, Val6, and Cys7). The interaction is established by 2 hydrogen bonds and 4 hydrophobic interactions. However, the complex is very sensitive to temperature because it can easily change its structure and stability. In the present study, docking experiment was undertaked to evaluate the stability of E-Chaderin..ADTC5 complex in different temperature and water solvent. The temperature range for computational investigation was between 295 K – 320 K with 5 K theshold. The method used in this research is molecular mechanics based on the Newton equation. The results obtained in this simulation are conformation, total potential energy, the radius of gyration, RMSD, RMSF, and MM/PBSA Calculation. The analysis results show that an increase in temperature can change the conformation and stability of the E-Cadherin..ADTC5 complex. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of the self-diffusion of thorium cations in ThO2 nanocrystals with a free surface is conducted. It is shown that a vacancy in the bulk of a crystal initiates a complex collective movement of cations, in which the interstitial positions surrounding the vacancy are involved. The diffusion coefficients of cations in the temperature range are calculated. The effective activation energy of diffusion is ED = (7.6 ± 0.7) eV. [ABSTRACT FROM AUTHOR]

In spite of the discontinuous nature of solar energy, concentrated solar power (CSP) plant with thermal energy can not only stabilize output but also be operated as a peak load regulation plant in a multi-energy system. This work demonstrates the dynamic characteristics of the key heat transfer components and thermal transport processes of a solar power tower (SPT) plant with thermal energy storage, which is operated under the disturbances of external environment and electricity demand. A 50MW commercial power tower plant is chosen as the study object. Detailed systematic dynamic models based on two modelling method of essential sub-systems are developed, implemented, and integrated into TRNSYS to improve the reliability of simulation as well as the prevision accuracy. The model is completed with a control strategy that regulates the water level in the evaporator efficiently. System-level simulation is conducted by two time scales, during a couple of minutes, and on a couple of hours. It is shown that the model can provide theoretical reference data for the unit operating characteristic analysis, predict the trend of the plant thermal characteristics. The thermal transport characteristics in the steam generation system and steam turbine have been revealed, which is useful for the study of regulatory mechanisms for a peak-shaving plant. [ABSTRACT FROM AUTHOR]

The simulation study of colloidal suspensions is important to control the release of active ingredient such as in pharmaceutical industry. In this work, we used Brownian Dynamic simulation to study structural properties colloidal suspensions. The size ratio of large to small particles in the bidisperse colloidal suspension is varied at 2:1, 3:1, 4:1, 5:1, 8:1 and 10:1. The interaction of aggregates (clusters) formed through DLVO and soft sphere interactions in a bi-dispersed suspension were studied. We found that the structural properties of bidisperse is correlated by varying the size ratio of bidisperse particles. [ABSTRACT FROM AUTHOR]

Due to ultrathin nanostructure, the highest specific surface area, the exceptional surface to volume ratio, 2-D materials exhibit diverse and dramatically improved properties. These properties are further dependent on their shapes and sizes. Among the 2-D materials, although lots of investigations on graphene have been carried out and are still going on, borophene nanotube has not received much attention so far for the analysis of mechanical properties. The present study focuses on molecular dynamic simulation with Stillinger-Weber potential for borophene nanotube to explore and evaluate its mechanical properties. The mechanical properties, such as yield strength and modulus of elasticity, of borophene nanotube at different strain rate have been evaluated. It is found that the modulus of elasticity decreases with the increase of strain rate during tension where the tensile loading is applied along the axial direction of the tube. Yield strength and modulus of elasticity decrease with the increase of temperature. The effects of the diameter and percentage of defect on the mechanical properties of borophene nanotube have also been investigated during tension. Mechanical properties evaluated in the present study are found to be much better in comparison with those of other 2-D materials. The obtained results are expected to be useful for near-future technical applications. [ABSTRACT FROM AUTHOR]

The research of molecular dynamic simulation by classical mechanic method on Mg-xZn has been done. The goal of this research is to find out Mg-xZn's structure after it's been given temperature treatment and how it's mechanical properties. Potential which been used are Embedded Atomic Method (EAM), Stillinger and Weber (SW), and Lennard- Jones (LJ). The structure of Mg-xZn before temperature treatment was HCP. Mechanical properties which observed are elastic constant and bulk modulus. Temperature treatment simulation was conducted before mechanical properties simulation is done by doing heating- cooling process simulation on the fixed material's structure. Elastic constant value on Mg-xZn which has low percentage of Zn is higher than the one which has high percentage. Elastic constant value from melting treatment is higher than sintering treatment. Elastic constant that its value is approaching good mechanical properties is sintering treatment Mg-7Zn which has C11, C12, and C44 is 34,05 GPa, 12,79 GPa, and 1,33 GPa respectively. [ABSTRACT FROM AUTHOR]

Two alternative sets of interaction potentials of a xenon atom with the ionic environment in the plutonium dioxide crystal are compared with respect to the simulation of high-energy processes. It is shown that an increase in the hardness of the potentials at the interaction energies near and above 1000 eV significantly increases the fraction of energy transferred to xenon bubbles by collision cascades, also lowering the threshold energy of displacement of the xenon atom. [ABSTRACT FROM AUTHOR]

Molecular dynamic simulation of helium diffusion within a ring dislocation inside a stoichiometric UO2 nanocrystal was carried out. Two different sets interaction potentials were used. One of the sets was characterized by a significantly stronger binding of helium to the crystal lattice. Temperature dependencies of the diffusion coefficient along the dislocation line were obtained. It was shown that the strengthening in the binding of helium led both to a decrease in the diffusion coefficient of the atom and to an increase in the temperatures at which the model dislocation was annealed. [ABSTRACT FROM AUTHOR]

A molecular dynamics simulation of helium diffusion in solid CaF2, SrF2, and BaF2 was carried out using the empirical pair potentials reproducing the experimental strong binding of helium to cations in these crystals. The model diffusion coefficients and activation energies are determined. [ABSTRACT FROM AUTHOR]

This work is connected with the problem of the dynamic loading of initially damaged media. The deformable solid medium with a complex internal structure is considered. The process of fracturing can drastically decrease the material stiffness and affect the wave propagation process. The continuum model of solid media with a discrete set of slip planes and nonlinear viscous-plastic contact conditions on them is formulated. It allows to simulate the dynamic behavior of complex media, like composite materials or geological fractured massifs. For a stable numerical solution of a system of differential equations, an explicit-implicit method is derived with an explicit approximation of motion equations and an implicit approximation of the constitutive relations containing a small parameter. To achieve a high precision, the hyperbolic part is solved with the grid-characteristic method on rectangular grids. In this research we compared simulated wavefields with the same ones obtained by the method of explicitly setting crack positions. The results can be useful for the problem of the low impact damage estimation. [ABSTRACT FROM AUTHOR]

Plant developers of parabolic trough collector (PTC) systems for industrial steam generation face various challenges. Some of the main challenges are availability of land, buildings in the vicinity of the plant that cast shadows on the collectors as well as land restrictions. The typical north-south collector axis alignment in many cases may not be possible due to limits of available ground. These were challenges that were faced in the planning phase for installing a PTC plant on the premises of the KEAN Soft Drinks Ltd factory in Limassol, Cyprus. As these issues cannot be avoided they must be accounted for by the plant developer, especially when a performance guarantee is given. This work presents, amongst other things, factors that should be analysed in order to predict the energy yield in the planning phase as best as possible by using a simulation model. In the sensitivity study presented in this paper, several effects on the energy yield were investigated theoretically. These effects include: Tracking inaccuracy, non-parallel collector row axis orientations as well as north-south vs. east-west collector alignment. A dynamic simulation model developed by the Solar-Institut Jülich (SIJ) [1] was further developed and used for the analysis. The simulation model features a deviation between the measured and simulated oil temperature at the collector outlet of only 1.5 K (rms). The findings are presented in this paper and give an insight into the effectiveness of mid-sized PTC systems for the industry sector. [ABSTRACT FROM AUTHOR]

The most solar-specific components in a Concentrated Solar Power (CSP) plant are the solar field and the receiver. The latter is exposed to extreme working conditions as it withstands high heat fluxes and temperatures in a corrosive environment during usual and transient conditions. It is then of paramount importance to assess the thermal behavior of such a fundamental component of the plant. The object-oriented modelling paradigm enables precise dynamic analysis of physical systems through the solution of sets of equations derived following an acausal approach. This guarantees modularity and description of interactions through physical connection equations with no causality specification. The application of the object-oriented modelling technique on the external receiver of a CSP tower plant is described in detail in this paper, proving its potentialities and modelling capabilities. The model is first verified against data available in literature and then applied for the analysis of dynamic operations, including typical issues of CSP plants as the impact of clouds and heliostats soiling. [ABSTRACT FROM AUTHOR]

The aim of this paper is to explore the possibilities of applying a simple method of the solution of the differential equations of the 2nd order. Such equations describe the behavior of the structure under dynamic load (seismic effects, starting of rotating machines). A friction damper was developed at the Fraunhofer-Institut für Holzforschung in Braunschweig in order to limit the oscillation of the structure. Here is analyzed the mathematical model where hysteresis behavior (energy dissipation) is described. The model is basically based on a strongly non-linear stiffness change of the joints. [ABSTRACT FROM AUTHOR]

The effect of sample concentration on radio frequency magnetic field induced heating of oil-based dispersions of oleic acid capped superparamagnetic Fe3O4 nanoparticles was studied. The sample concentration was varied from 2.5-23 wt. % and field induced heating studies were carried out at a fixed frequency of 126 kHz and at five different amplitudes. Heating efficiency was foundto linearly increase with the square of field amplitudes, in accordance with the linear response theory. Theoretical results on heating efficiency, obtained from high frequency dynamic loop simulations, were in agreement with the experimental findings. The increase in heating efficiency with MNP concentration was attributed to the higher ratio of anisotropy energy to dipolar energy. With increase in MNP concentration, dipolar interaction did not enhance significantly, whereas effective number of heat sources per unit volume increased leading to a larger heating efficiency at higher loading. [ABSTRACT FROM AUTHOR]

The double-articulated scissors wrecker device was taken as the research object, and its motion analysis and mechanical analysis are performed. The dynamics property of scissors wrecker device was analyzed using by ADAMS software. The influence of the control function for the dynamic property was studied, and the optimum project of control function was acquired. The methods and conclusions are available for designers of scissors wrecker device and hydraulic circuit. [ABSTRACT FROM AUTHOR]

With a biodegradation rate exceeding 90%, TMPTO, a polyol ester, is used as a base oil for bio-lubricant. Its excellent physicochemical properties, made TMPTO based bio-lubricants applied as metalworking fluids such as in hydraulics, chains and machines. In this study, TMPTO is derived from chemical reactions between Trimethylolpropane (TMP) and the methyl ester which synthesized from plant oils such as palm and Jatropha curcas. With hBN nanoparticles addition, it is expected improving its heat transfer capability. This study is predicting the thermal conductivity of TMPTO with various hBN nanoparticles concentration using the molecular dynamics simulation method. The thermal conductivity value is computed using Green-Kubo formalism, and it is applied to compute the heat flux vector based on a contribution from atoms in the specified group. Based on simulations, we get the best thermal conductivity value around 0.255 – 0.375 W/mK, which performed by TPMTO with a 0.4% hBN addition. [ABSTRACT FROM AUTHOR]

The simulation study of colloidal suspensions is important to control the release of active ingredient such as in pharmaceutical industry. In this work, we used Brownian Dynamic simulation to study structural properties colloidal suspensions. The size ratio of large to small particles in the bidisperse colloidal suspension is varied at 2:1, 3:1, 4:1, 5:1, 8:1 and 10:1. The interaction of aggregates (clusters) formed through DLVO and soft sphere interactions in a bi-dispersed suspension were studied. We found that the structural properties of bidisperse is correlated by varying the size ratio of bidisperse particles. [ABSTRACT FROM AUTHOR]

This research aimed to identify the effect of punch speed and tool blanking material on the quality of the sheared edge bone-implant product in the form of a keychain cranioplasty plate implant. This research used Ti-6AL-4V sheet metal, 2.5% clearance between punch-die, various punch speeds, and materials of tool blanking. The tool blanking material used the standardized equipment for the blanking process. The sheared edge characteristic with the swift punch and high elastic modulus improved the shear zone 75% more of the workpiece thickness. The utilization of 71.76 mm/s speed and AISI M2 material created a smoother sheared edge of keychain cranioplasty plate compared to the others. [ABSTRACT FROM AUTHOR]

Indonesia’s economic and population growth is predicted to increase energy needs by 4.1 GW each year until the year 2030. This increase in energy needs will be supplied by fossil fuels. Most of the energy consumption is in the household and commercial sector, taking up 61.5% of the total electrical consumption. Hence, reducing energy consumption in this sector is critical. A method known as Building Performance Simulation enables to simulate a building energy consumption, given the climate condition, building envelope properties, occupants activity pattern, lighting system and other components of the building cooling load. Strategies can be applied in the simulation to improve building energy performance. Simulation of a building that serves as a learning center in Universitas Gadjah Mada was conducted utilizing the IES-VE software. The LC-FEB is an eight-story building consists of rooms that functionalize as a library, audiovisual room, modern learning activity room, and instructional development service. This research is conducted to analyze the cooling load components that have the most impact, particularly for hot humid climate and a learning center building. A systematical method for cooling load calculation is proposed. From this study, it can be concluded that the largest heat gain comes from people heat gain (46%), followed by solar heat gain (18%), lighting heat gain (14%), natural ventilation heat gain (12%), and equipment heat gain (10%). It is shown that people's heat gain contributes the most to the overall cooling load. However, given the building function as a learning center, this particular load is considered already fixed for scenarios defined by the number of people and the type of activity. A passive design strategy that variates the building envelope by carefully taking into account the Yogyakarta’s climate condition, can be considered potential to reduce the solar heat gain component and therefore, reduces the total cooling load. It can conclude that for a learning center building, activity inside the building should be designed carefully. For a hot humid climate, the design of the building envelope should respond to the climate condition. This research shows that building thermal dynamics simulations will provide the opportunity for researchers to know directly what components need more attention in designing efficient buildings. [ABSTRACT FROM AUTHOR]

The problem encountered on the regasification terminal is unsteady operating because of unloading from LNG carrier to storage and holding mode that involves the on-off operation of Ambient Air Vaporizer (AAV) caused by frosting. The purposes of this study are to simulate a dynamic operation of small-scale regasification terminal using AAV with and without controls by process simulator UniSim. The result of the simulation without controls, shows that the gas flow rate has deviated 14% from the target, after 4 hours of operation output gas temperature is below 2.5°C, it cannot meet the requirements of the gas power plant. For simulation with controls, a digital on-off type controller is used for pump during unloading and switch or on-off between AAV, while PI type controller is used to control LNG flow rates. For the digital on-off controller, the controller is set to stop the unloading process when the remaining LNG in the carrier is 10% (350m³) and the other digital on-off controller will be set to act on switching AAV when the AAV gas sent out temperature reaches 3°C. For PI controllers, the tuning parameters to regulate the flow rate is Kc = 0.00638 and Ti = 0.00043. The maximum operating time for 1 AAV is 5 hours 15 minutes before it will be switched for defrosting and replaced with other AAV. After the controller installed, the gas sent out specifications from the terminal able to meet the requirements of the power plant, a molar flow rate of 6.53 MMSCFD and a minimum gas temperature of 2.5°C throughout the operating time. [ABSTRACT FROM AUTHOR]

Liquefied natural gas (LNG) is the most economical way of transporting natural gas over long distances. During LNG transportation and storage at -163 °C, boil-off gas (BOG) losses are unavoidable, its effects on the quantity and quality of natural gas. The number of BOGs that are formed along the supply chain changes over time. This study aims to determine the amount of BOG formed and changes in gas quality such as the Wobbe Index, methane number and heating value along the supply chain and also to determine the effect of shipping distance. The method used is a dynamic simulation process using UniSim Design R390.1 software. The results show 2,966 m³ of BOG occurred in the LNG loading process, corresponding to 2.7% of total LNG carried. For the shipping process, 4,118 m3 (4%) of the remaining LNG turn into BOG and 2,545 m3 (2.63%) of the remaining LNG in the unloading process. Longer shipping time causes heating value, Wobbe Index to increase and reduce the methane number. [ABSTRACT FROM AUTHOR]

The aim of this paper is to detail the creation of a roller bearing model in the Adams program suite for subsequent dynamic analysis and to obtain information about different parts of the bearing during the simulation. The bearing model was made so as to closely resemble its real-life counterpart, which allows us to estimate load conditions, dynamic conditions of individual bearing parts and interactions between them. [ABSTRACT FROM AUTHOR]

Radiant heating plants have become increasingly popular in the last decades, particularly for industrial applications. Generally, they are high temperature radiant heating type, even if more recently low temperature radiant floors have increased their spread due to the increased thermal insulation of buildings. Moreover, radiant floors allow for cooling as well. In this paper, energy performance of a high temperature radiant tubes heating plant coupled to a condensing system for the climatization of an industrial building are investigated by dynamic simulation. A Trnsys type is modified in order to simulate the behavior of the high temperature condensing system: both the radiative (between the heating and the surrounding surfaces) and the convective heat exchanges with suitable devices (like baffles applied in order to reduce convection and consequent thermal stratification) are considered. Energy performance is compared to that of two more traditional plants such as warm air heater, and low temperature radiant floor coupled to condensing boiler. Finally, some considerations about the energy performance of the radiant tubes system in cooling mode are reported. [ABSTRACT FROM AUTHOR]

With the aim of promoting Nearly Zero Energy Buildings in Panama, the implementation of low-consumption techniques is studied here via dynamic simulations. For this, a Test model based on the generic construction materials for envelope composition implemented in Panama’s standard buildings was developed in DesignBuilder software to evaluate some low-consumption techniques, such as occupancy profile change, free cooling strategies, and modifications of the envelope composition. The envelope composition of an NZEB encountered in Playa Venao, Panama, is also examined. After implementing the low-consumption techniques, the net energy consumption of the Test model remains far from laying within the energy ranges to be considered as an NZEB. However, this numerical study has shown promising results using few low-consumption techniques, which have managed to reduce the energy consumption of the building in 35% with respect to the original energy consumption of the Test model reference. [ABSTRACT FROM AUTHOR]

In this work the 3DCell method has been extended to the thermo-fluid dynamic simulation of an automotive turbocharger’s compressor. The 3DCell, an approach continuously developed by the authors at Politecnico di Milano, is based on a pseudo-staggered leapfrog method that allows to decompose a generic 3D problem in a set of 1D scalar equation arbitrarily oriented in space. The system of equations has been solved referring to a relative rotating framework for the moving components, whereas to an absolute reference elsewhere. The domain has been discretized on a basis of a polar coordinate system, identifying five macro sub-domains, namely the inlet pipe, impeller, vaneless diffuser, volute, outlet pipe, each treated numerically in a specific way. The diffuser’s momentum in the tangential direction has been modelled resorting to the conservation of the angular momentum, while the rotor channels are modelled as rotating pipes that exchange work and momentum with the blades as they experience a relative source term due to the centrifugal force field and its potential. The model has been validated against measurements carried out on a steady state flow test bench at University of Genoa. [ABSTRACT FROM AUTHOR]

The constant growth of renewable energy sources has changed the working condition of the modern power plants, where a greater flexibility of the conventional units is required. Large steam turbines, for instance, have to be capable of partial load operation as well as quick starts in order to ensure a stable functioning of the power grid. This reflects on the design of the steam turbine and in particular on exhaust hoods which have a significant impact on the overall turbine performance, recovering the energy left and therefore affecting the power output. Exhaust hoods have to convert kinetic energy at the turbine last stage exit into static pressure at the condenser by decreasing the flow speed. In axial-radial hoods the flow must turn by 90 degrees in a very short distance, therefore, if such components are not well designed, this may lead to flow separation phenomena which reduce the hood recovery performance. Due to the nowadays operational requirements, it is mandatory to carefully design the steam turbine exhaust system for a wide range of operating conditions, in order to ensure high efficiencies also at partial loads. This work concerns a numerical investigation on a low-pressure steam turbine exhaust hood through computational fluid dynamic simulations, assessing several numerical methods to couple the exhaust casing with the turbine rear stage. The numerical outcomes were compared in terms of flow field distribution and pressure recovery coefficient, by allowing to define a numerical setup which is a good trade-off between results accuracy and computational effort. [ABSTRACT FROM AUTHOR]