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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]