Simulation Modeling Approach Research Articles

PENGUKURAN TINGKAT RISIKO DAN KEUNTUNGAN SAHAM INDIVIDUAL DENGAN MENGGUNAKAN PENDEKATAN HISTORIS PADA METODE VALUE AT RISK (VaR) (STUDI KASUS TOP 10 SAHAM TERBAIK JANUARI 2022)

In research has been conducted to measure individual daily in January 2022 which is included in the Top 10 best stocks version of kontan.co.id risk and profit level using the Value at Risk (VaR) approach. The research method used to analyze the data refers to the Historical Simulation Model approach. The data used is the daily asset return data obtained from the daily closing price of shares during the January 2021 period. The results of the VaR method approach are Historical Simulation. The model shows CMPP stock with a risk of 91 million. The measurement results show that if the funds invested are Rp. 500,000,000.00 with a 95% confidence level, the period is 21 days.

Models for Assessing Urban Ecosystem Services: Status and Outlooks

Urban ecosystem services provide many benefits for human beings. Given the dramatic increase of urbanization, maintaining sustainability of cities relies heavily on ecosystem services, and it is crucial for quantifying, managing, and optimizing urban ecosystem services to promote social and ecological sustainable development. This study presents the review of models for assessing urban ecosystem services through gathering the pertinent literatures which were published recent years. The main types of approaches for assessing urban ecosystem services were summarized, and the model simulation approach was detailed. From modelling techniques to the existing models, it was found that a process-based model is, relatively, a better way to detect the mechanism of urban ecological processes and simulate the future dynamic changes of urban ecosystem services. Three key limitations of existing products and frameworks were identified: (1) lacking understanding of multiple urban ecosystem services interactions, (2) ignoring accounting the socioeconomic factors into dynamics of urban ecosystem, and (3) lacking considerations of feedback effects between social system and urban ecosystem. The study concludes with outlooks that a comprehensive social-ecosystem model based on the social-ecological framework is helpful to reveal the relationships and interactions among various urban ecosystem services, and can better assess how human-induced urban growth affects ecosystem services, and better describe the feedback effect between the social environment and urban ecosystem services, as well as dynamically predict the changes of urban ecosystem services under different scenarios in future long time series.

A rational hybrid RANS-LES model for CFD predictions of microclimate and environmental quality in real urban structures

We report on the application and comparative assessment of two rational turbulence modelling approaches for the computer simulation of air flow and pollutant dispersion in real urban environment: a stand-alone unsteady Reynolds-averaged Navier-Stokes eddy-viscosity model (URANS), and its blend with Large-eddy simulations (LES) in a hybrid mode (HRL). The elliptic-relaxation (k−ε)ζ−feddy-viscosity model was applied in both methods. The models, verified earlier in a range of engineering flows including heat transfer, were here validated in two environmental benchmark cases, a single building and an idealized urban settlement, both subjected to a steady wind. The velocity field and pollutant concentration are better predicted by the HRL method in both benchmarks. The HRL is then applied to predictions of air flow and spreading of pollutant from road traffic in downtown of a real city (Sarajevo) containing 100 realistic buildings. The simulations were performed with the in-house open-source CFD code T-Flows, specifically optimized for a fast and efficient high-quality unstructured meshing of the terrain orography and building configurations. The benchmark validations demonstrated that, compared with the standard k−ε, in typical urban applications with complex urban shapes and arrangements the accuracy and credibility of the predictions can substantially be improved by applying a physically sounder and yet still relatively simple ζ−f eddy-viscosity model that specifically accounts for the elliptic inviscid wall-blocking effects and near-wall stress anisotropy. The benchmarking also showed that still further improvements are achieved by using the HRL scheme which ensures a rational balance in capturing the important physics and the computational economy.

The Molecular Basis of the Effect of Temperature on the Structure and Function of SARS-CoV-2 Spike Protein

The remarkable rise of the current COVID-19 pandemic to every part of the globe has raised key concerns for the current public healthcare system. The spike (S) protein of SARS-CoV-2 shows an important part in the cell membrane fusion and receptor recognition. It is a key target for vaccine production. Several researchers studied the nature of this protein under various environmental conditions. In this work, we applied molecular modeling and extensive molecular dynamics simulation approaches at 0°C (273.15 K), 20°C (293.15 K), 40°C (313.15 K), and 60°C (333.15 K) to study the detailed conformational alterations in the SARS-CoV-2 S protein. Our aim is to understand the influence of temperatures on the structure, function, and dynamics of the S protein of SARS-CoV-2. The structural deviations, and atomic and residual fluctuations were least at low (0°C) and high (60°C) temperature. Even the internal residues of the SARS-CoV-2 S protein are not accessible to solvent at high temperature. Furthermore, there was no unfolding of SARS-CoV-2 spike S reported at higher temperature. The most stable conformations of the SARS-CoV-2 S protein were reported at 20°C, but the free energy minimum region of the SARS-CoV-2 S protein was sharper at 40°C than other temperatures. Our findings revealed that higher temperatures have little or no influence on the stability and folding of the SARS-CoV-2 S protein.

ANALISIS KINERJA SIMPANG EMPAT NONONGAN DENGAN PENGGUNAAN WAKTU SINYAL DOUBLE CYCLE PADA PENERAPAN CONTRA FLOW BUS LANE

<p><em>Traffic jams and accidents on urban roads are a challenge for the city government in carrying out traffic management and engineering efforts. The intersection is the meeting point of various traffic movements from each intersection approach that has the potential to cause traffic jams and accidents. One of the traffic management and engineering efforts carried out by the Surakarta City Government is by providing public transportation services for Batik Solo Trans in serving the movement of people's journeys. The implementation of the contra flow bus lane on Jalan Brigjen Slamet Riyadi, Surakarta City is part of the Surakarta City Government's efforts to provide a reliable public transportation system. However, the implementation of the contra flow bus lane has an impact on the performance of signalized intersections along Jalan Brigjen Slamet Riyadi, one of which is the Nonongan Empat Junction. This study aims to streamline the timing of the APILL signal by using a double cycle at the Simpang Empat Nonongan. Evaluation of intersection performance uses a simulation modeling approach with the VISSIM simulation program. The results of the Base output performance of the VISSIM simulation model with the existing signal time are compared with the VISSIM simulation model scenario using a double cycle signal time. The use of double cycle signal time shows the intersection performance is more effective than using the existing signal time. Intersection delays decreased by 13.6% for the morning rush hour and 18.8% for the afternoon rush hour.</em><strong> </strong></p>

How human-robot collaboration impacts construction productivity: An agent-based multi-fidelity modeling approach

Though construction robots have drawn attention in research and practice for decades, human-robot collaboration (HRC) remains important to conduct complex construction tasks. Considering its complexity and uniqueness, it is still unclear how HRC process will impact construction productivity, which is difficult to handle with conventional methods such as field tests, mathematical modeling and physical simulation approaches. To this end, an agent-based (AB) multi-fidelity modeling approach is introduced to simulate and evaluate how HRC influences construction productivity. A high-fidelity model is first proposed for a scenario with one robot. Then, a low-fidelity model is established to extract key parameters that capture the inner relationship among scenarios. The multi-fidelity models work together to simulate complex scenarios. Based on the simulation model, the twofold influence of HRC on productivity, namely the supplement strategy on the worker side, and the design for proactive interaction on the robot side, are fully investigated. Experimental results show that: 1) the proposed approach is feasible and flexible for simulation of complex HRC processes, and can cover multiple collaboration and interaction modes; 2) the influence of the supplement strategy is simple when there is only one robot, where lower Check Interval (CI) and higher Supplement Limit (SL) will improve productivity. But the influence becomes much more complicated when there are more robots due to the internal competition among robots for the limited time of workers; 3) HRC has a scale effect on productivity per robot, which means the productivity improves if there are more robots and workers, even if the human-robot ratio remains the same; 4) introducing proactive interaction between robots and workers could improve productivity significantly, up to 22% in our experiments, which further depends on the supplement strategy and the human-robot ratio. Overall, this research contributes an integrated approach to simulate and evaluate HRC’s impacts on productivity as well as valuable insights on how to optimize HRC for better performance and occupational health. The proposed approach is also useful for the evaluation and development of new robots.

Conceptual System Dynamics and Agent-Based Modelling Simulation of Interorganisational Fairness in Food Value Chains: Research Agenda and Case Studies

System dynamics and agent-based simulation modelling approaches have a potential as tools to evaluate the impact of policy related decision making in food value chains. The context is that a food value chain involves flows of multiple products, financial flows and decision making among the food value chain players. Each decision may be viewed from the level of independent actors, each with their own motivations and agenda, but responding to externalities and to the behaviours of other actors. The focus is to show how simulation modelling can be applied to problems such as fairness and power asymmetries in European food value chains by evaluating the outcome of interventions in terms of relevant operational indicators of interorganisational fairness (e.g., profit distribution, market power, bargaining power). The main concepts of system dynamics and agent-based modelling are introduced and the applicability of a hybrid of these methods to food value chains is justified. This approach is outlined as a research agenda, and it is demonstrated how cognitive maps can help in the initial conceptual model building when implemented for specific food value chains studied in the EU Horizon 2020 VALUMICS project. The French wheat to bread chain has many characteristics of food value chains in general and is applied as an example to formulate a model that can be extended to capture the functioning of European FVCs. This work is to be further progressed in a subsequent stream of research for the other food value chain case studies with different governance modes and market organisation, in particular, farmed salmon to fillet, dairy cows to milk and raw tomato to processed tomato.

Calibration of a continuous hydrologic simulation model in the urban Gowrie Creek catchment in Toowoomba, Australia

Study regionToowoomba, Queensland, Australia Study focusIn this study we derive loss model parameters suitable for use in the dynamic loss Australian Representative Basin Model (ARBM) through the calibration of a continuous simulation hydrologic model. We compare the derived parameters to those published in the literature, and our results highlight the need to develop a database of calibrated loss parameters for urban catchments. New hydrological insightsThe development of design storms for flood modelling commonly uses the initial loss/continuous loss model to estimate the conversion of rainfall to runoff. This loss model, when applied to pervious areas, uses parameters that have been calibrated for gauged rural catchments. These same parameters are often applied to the pervious component of ungauged urban catchments with minimal understanding of the resulting impact on runoff. This research uses a continuous simulation modelling approach to calibrate parameters suitable for use in the ARBM loss model built into the hydrological modelling software XPRAFTS. Through a two-stage calibration approach, the model offered a satisfactory fit (Nash Sutcliffe Efficiency > 0.5) for 9 of the 11 selected storm events, with seven events exceeding a Nash Sutcliffe Efficiency of 0.75. Events used in the calibration/validation included peak flows as low as 9 m3/s and as high as 600 m3/s. Developing these loss model parameters offers new insights into the suitability of a dynamic loss model approach in an urban catchment in regional Australia and provides an alternative to the parameters already available in the literature which were found to overestimate the peak flow in frequent events.

Autoregressive Modeling Approach for Non-Stationary Vehicular Channel Simulation

A framework is proposed for long-term vehicular channel simulation based on the vector time-frequency autoregressive (VTFAR) model for a sparse parametric description of nonstationary multivariate random processes. Based on vehicle-to-infrastructure tunnel measurements, we estimate the VTFAR model parameters and validate the model by comparing the parametric and non-parametric spectra of the measured channel in terms of the delay spread and stationarity time. In addition, the VTFAR model stability is investigated and an approximation for the correlated scattering channel is proposed. The experimental validation shows a good agreement with RMSE of only 0.01 for the delay spread and 0.4 for the stationarity time. This approach provides an efficient alternative for non-stationary channel simulation that is measurement-based and computationally inexpensive.

Analysis of pressure wave signal generation in MPT: An integrated model and numerical simulation approach

Mud pulse telemetry (MPT) is one of the essential means to ensure a high transmission rate of downhole data. Continuous-wave mud pulse has a high transmission rate, strong stability, and outstanding adaptability, the most widely used downhole data transmission mode. One factor that restricts the high transmission rate of downhole data is the quality of the pressure wave generation signal. However, there is a lack of complete mathematical modeling research methods. Based on CFD theory, a numerical model of the integration of pulse generator and upstream and downstream pipelines was established for the first time, as well as the corresponding grid division process, which was to simulate the pressure wave generation and propagation process under drilling conditions, and the sensitivity analysis of parameters was carried out. The results show that the pressure drop curve derived from the thin-wall throttling theory is not the actual pressure wave, so the optimization results have a particular theoretical error. In fact, with the periodic change of the flow area, the upstream and downstream synchronously generate compression waves and expansion waves, which propagate and gradually decay. The amplitude of pressure wave increases with the increase of displacement and density but decreases sharply with the increase of gap height. Meanwhile, the amplitude does not change with the frequency and viscosity, but it aggravates the propagation attenuation of the pressure wave. Moreover, it is observed that the pressure wave is not a perfect sine wave in the case of sinusoidal rotor rotation, which needs further study. The research results of this paper provide a technical means for the optimization of downhole pressure wave generation, transmission, and noise reduction and help improve the transmission rate of downhole data.

A review on key aspects of wet granulation process for continuous pharmaceutical manufacturing of solid dosage oral formulations

Wet granulation process is a major unit operation in production of pharmaceuticals as solid dosage oral formulation. Indeed, granulation is used to improve the formulation properties such as flowability, compressibility, and so on for pharmaceutical manufacturing. Different types of granulations can be used in pharmaceutical manufacturing in which the selection of proper process depends on the operational conditions as well as formulation properties. In current decades, twin-screw wet granulation has been of paramount interest owing to its superior properties. Pharmaceutical manufacturing industry are trying to move towards continuous mode by which the efficiency can be improved compared to the batch mode. Therefore, development of continuous granulation process is of great importance. In this review article, various processing units applicable for wet granulation of pharmaceutical formulations for solid dosage forms are reviewed and discussed. The advantages and disadvantages of the processes are discussed and listed along with modeling approaches for simulation of process. The governing models and numerical schemes applicable for design of wet granulation are also critically discussed. The main focus is on wet granulation as this method has attracted much attention in pharmaceutical processing.

Detached eddy simulation of turbulent flow fields over steep hilly terrain

The verification and validation (V&V) of multi-fidelity turbulence models is crucial for the efficient and reliable industrial application of computational fluid dynamics (CFD). This study aims to evaluate the performance of detached eddy simulation (DES) modeling approaches embedded with various unsteady Reynolds Averaged Navier-Stokes (URANS) models in simulating the turbulent flow fields over a steep-sloped hill. And the high-fidelity numerical methodology based on the DES model was proposed and analyzed in the context of URANS modes, mesh resolution and sampling duration. In comparison with the experimental data, the shear stress transport (SST) k-ω based DDES (Delayed Detached eddy simulation) turbulence model (DDES SST k-ω) could better predict the profiles of mean velocity and turbulence fluctuation, while the Spalart-Allmaras (S-A) based DES and DDES turbulence models show its stronger capability to reproduce the spectral characteristics. Additionally, in contrast to DES S-A and DDES S-A, a larger time-averaged separation bubble was predicted by DES SST k-ω and DDES SST k-ω. Moreover, the instantaneous flow patterns such as the formation and evolution of turbulent eddies in the hill wake could be reasonably reproduced by DES S-A and DDES S-A. Furthermore, the numerical results obtained from DES models were sensitive to URANS modes and vertical mesh resolution but trivially affected by the increase in sampling time after reaching the statistical convergence.

Understanding the Rheological Transitions in Semi-Solid Alloys by a Combined <i>In Situ</i> Imaging and Granular Micromechanics Modeling Approach

To gain better understanding of rheological transitions from suspension flow to granular deformation and shear cracking, this research conducted shear-deformation on globular semi-solid Al-Cu alloys to study the rheological behavior of semi-solid as a function of solid fraction (38% - 85%) and shear rate (10-4 – 10-1 s-1) under real-time synchrotron radiography observation. By analyzing 17 X-ray imaging datasets, we define three rheological transitions: (i) the critical solid fraction from a suspension to a loosely percolating assembly; (ii) from the net contraction of a loose assembly to the net dilation of a densely packed assembly, and (iii) to shear cracking at high solid fraction and shear rate. Inspired by in-situ observations of semi-solid deformation showing a disordered assembly of percolating crystals in partially-cohesive contact with liquid flow, we reproduced a two-phase sample using the coupled lattice Boltzmann method-discrete element method (LBM-DEM) simulation approach for granular micromechanical modeling. In DEM, each globular Al grain is represented by a discrete element, and the flow of interstitial liquid is solved by LBM. The LBM-DEM simulations show quantitative agreement of semi-solid strain localization with the experiments and are used to explore the components involved in the shear rate dependence of the transitions, and the role of liquid pressure on the initiation of shear cracking.

Effect of applying independence axiom of Axiomatic Design theory on performance of an Integrated Manufacturing Information System: a computer simulation modeling approach

To control manufacturing processes, integration of flows of manufacturing information is an important starting point. In this regard, an effective Integrated Manufacturing Information System (IMIS) which is capable of monitoring, analyzing, and inspecting manufacturing processes properly is critical. Often, most of difficulties in achieving an effective IMIS stem from a poor design for the system architecture. This study particularly addresses the problem of coupling in architecture of an IMIS and its effect on the system performance. This study employs “Independence Axiom” of the Axiomatic Design (AD) theory to deal with the problem and uses “times in process” and “utilized capacities of available resources” as two important criteria for evaluating the system performance. To verify the proposed methodology, a real IMIS is addressed, its stochastic behavior is simulated in Visual SLAM and AweSim (version 3.o) software environment, and the outcomes are analyzed by using logistic regression method for each level of system decomposition. Results of the analyses indicate that fulfillment of independence axiom of AD theory can significantly enhance performance of the concerned IMIS.

The Performance of Wastewater Surveillance for the Early Detection of Local SARS-CoV-2 Outbreaks in Low Incidence Situations: A Simulation Modelling Approach

The Performance of Wastewater Surveillance for the Early Detection of Local SARS-CoV-2 Outbreaks in Low Incidence Situations: A Simulation Modelling Approach

A proposal of data-driven multi-scale modeling approach for production flow simulation

A proposal of data-driven multi-scale modeling approach for production flow simulation

Can Postoperative Geometric Changes Help to Explain Pancreatic Leaks in Pancreaticoduodenectomy?

Introduction: Pancreatic leaks (PLs) occur after pancreatic resection in up to 30% of cases; this rate has been unchanged for decades. Numerous associated factors and proposed theories as to the etiology of PL, as well as preventative strategies regarding PL, have been detailed in the literature. However, the effect of the geometric changes in pancreaticoduodenectomy (PD) has received scant attention. In this work, computational fluid dynamics[ CFD] surgical models are constructed with the aim of comparing geometry pre and post operatively in PD. Methods: The CFD analysis comparing preoperative and postoperative states was performed using commercial software Ansys with Multiphase flow modeling approach for reliable numerical simulation of internal human organs. Mixtures of Euler-Euler multiphase model were used to compute the interactions of multiple fluids. All phases were treated as inter-penetrating continua with mixture momentum solved and each dispersed phase velocity was prescribed. Results: CFD 3D streamline distribution revealed a higher peak fluid velocity because the post-operative stomach size is smaller and more vertically positioned compared to preoperatively. In addition, the postoperative pancreas duct junction fluid flow velocity distribution is highly restrictive and in combination with altered geometry postoperatively, fluid velocity is much lower resulting in stagnation. Conclusion: CFD of the postoperative state reveals altered geometry resulting in altered flow and pressure patterns which could potentially contribute to PL. Future work will evaluate the difference in geometry with resection alone as well as possible interventions for clinically significant PL.

Performance analysis of single slope solar still under composite climate in India: Numerical simulation and thermal modeling approach

With increasing environmental concerns and depletion of fossil fuels, solar energy has grown significantly in producing potable water. 3D CAD model of solar still with single slope and single basin has been created. Multi-phase transient simulations were conducted in ANSYS FLUENT considering Delhi Technological University's climatic conditions (28.7501°N, 77.1177°E). Simulation findings of basin water temperature, condensing glass cover temperature, freshwater productivity was validated with experimental results of solar still and were found to be in good agreement. Thermal models developed by Dunkle, Clark, Kumar and Tiwari, and Adhikari model were also applied to predict and validate the performance evaluation of solar still with utmost accuracy. Characteristic equation of solar still has also been developed where instantaneous efficiency is plotted against (Tw − Ta)/I(t) with the value of R2 being 0.96 and 0.97 for linear and quadratic regression equations. An acceptable error of 12.7% between simulated output and experimental results was found.

Molecular Modeling Studies of Natural Inhibitors of Androgen Signaling in Prostate Cancer.

Prostate cancer is the second most common disease in men and the sixth leading cause of death from cancer globally, with 20 million men expected to be affected by 2024 thus considered as chronic illness which requires immediate attention. As an androgen-dependent illness that relies on the androgen receptor for development and progression, inhibition of the androgen receptor can lead to a therapeutic solution, hence serving as a vital therapeutic target. This study focused on the computational analysis of the inhibitory potentials of Vitis vinifera, a reported plant with anti-cancer properties, against androgen receptor employing molecular docking, ADMET studies, Binding energy study, pharmacophore modeling, and molecular dynamics simulation approaches. After the investigation, it was determined that 5 compounds: cis-piceid, cis-astrigin, gallocatechin, phlorizin, and trans-polydatin, might be possible androgen receptor inhibitors since they had higher docking scores and ADMET qualities than compared standards, with cis-piceid being the best-predicted inhibitor.

Pharmacokinetic, DFT Modeling, Molecular Docking, and Molecular Dynamics Simulation Approaches: Diptoindonesin A as a Potential Inhibitor of Sirtuin-1

Pharmacokinetic, DFT Modeling, Molecular Docking, and Molecular Dynamics Simulation Approaches: Diptoindonesin A as a Potential Inhibitor of Sirtuin-1