scholarly journals SOLVING THE BOTTLENECK PROBLEM IN A WAREHOUSE USING SIMULATIONS

2021 ◽  
Vol 8 (2) ◽  
pp. 107-116
Author(s):  
Jana Fabianova ◽  
Jaroslava Janekova ◽  
Jozef Horbulak
Keyword(s):  
Risk Factor ◽  
Computer Simulations ◽  
Simulation Analysis ◽  
Simulation Method ◽  
System Stability ◽  
Financial Resources ◽  
Customer Requirements ◽  
Financial Costs ◽  
Distribution Process ◽  
Workload Distribution

The uneven workload distribution and working time utilisation create a bottleneck, leading to inefficient utilisation of capacity and increased costs. A bottleneck is a limiting and risk factor for any business entity. In the case of a distribution warehouse, the bottleneck limits its ability to meet the requirements for sending an order within the required time limit. Delays at any phase of a distribution process may result in non-compliance with customer requirements. In solving capacity problems and bottlenecks elimination, computer simulations and optimisation are often used. The article presents a basic simulation analysis of workload distribution and work times, useful for logistics companies, thus for the area of human and financial resources. In the article, the use of simulations in the ExtendSim9 program to eliminate the bottleneck is discussed. The bottleneck is solved by experiments on a simulation model when optimal workers assignment to individual workplaces of the warehouse is sought. The two final proposals for workers allocation, with the current and increased number of workers, are compared in workforce utilisation and system stability. The simulation method allows verification of the proposals' impacts in advance and practically with no financial costs.

A Research of Shaft Modal Simulation Method Based on the Preloaded Angular Contact Ball Bearing

2013 ◽  
Vol 389 ◽  
pp. 364-370
Author(s):  
Bei Li ◽  
Jian Bin Zhang ◽  
Lu Sha Jiang
Keyword(s):  
Simulation Analysis ◽  
Simulation Method ◽  
Numerical Control ◽  
Angular Contact Ball Bearing ◽  
Tightening Force ◽  
Shaft System ◽  
Element Simulation ◽  
Rolling Element ◽  
Bearing Stiffness ◽  
Main Spindle

In order to analysis modal characteristic of bearing with pre-tightening force on main spindle of numerical control lathe, this paper proposes a model of spindle modality analysis. This model is used to simulate the preloaded bearing shaft system modal, and the simulation results are verified by modal experiment. This paper takes 7005c as the research object to establish the equivalent-spring model based on the Hertz theory considering the pre-tightening force, whose focus is dealing with the contact between bearings rolling element and raceway. Then the model will be used to get the bearing stiffness for finite element simulation analysis. The shafting modal with preloaded bearing test platform is structured to get the shaft system modal parameters, which is compared with and verified the simulation analysis.

Experimental and numerical investigation of the thermomechanical load on a turbine housing in a radial turbocharger

2021 ◽  
pp. 095440702110521
Author(s):  
Shaolin Chen ◽  
Hong Zhang ◽  
Liaoping Hu ◽  
Guangqing He ◽  
Fen Lei ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Fatigue Life ◽  
Simulation Analysis ◽  
Simulation Method ◽  
Testing Temperature ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Monitoring Point ◽  
Turbine Housing

The fatigue life of turbine housing is an important index to measure the reliability of a radial turbocharger. The increase in turbine inlet temperatures in the last few years has resulted in a decrease in the fatigue life of turbine housing. A simulation method and experimental verification are required to predict the life of a turbine housing in the early design and development process precisely. The temperature field distribution of the turbine housing is calculated using the steady-state bidirectional coupled conjugate heat transfer method. Next, the temperature field results are considered as the boundary for calculating the turbine housing temperature and thermomechanical strain, and then, the thermomechanical strain of the turbine housing is determined. Infrared and digital image correlations are used to measure the turbine housing surface temperature and total thermomechanical strain. Compared to the numerical solution, the maximum temperature RMS (Root Mean Square) error of the monitoring point in the monitoring area is only 3.5%; the maximum strain RMS error reached 11%. Experimental results of temperature field test and strain measurement test show that the testing temperature and total strain results are approximately equal to the solution of the numerical simulation. Based on the comparison between the numerical calculation and experimental results, the numerical simulation and test results were found to be in good agreement. The experimental and simulation results of this method can be used as the temperature and strain (stress) boundaries for subsequent thermomechanical fatigue (TMF) simulation analysis of the turbine housing.

scholarly journals From behavioural simulation to computer models: how simulation can be used to improve healthcare management and policy

2018 ◽  
Vol 6 (2) ◽  
pp. 95-102 ◽  
Author(s):  
Guillaume Lamé ◽  
Rebecca K Simmons
Keyword(s):  
Computer Simulations ◽  
Policy Making ◽  
Simulation Method ◽  
Healthcare Management ◽  
Policies And Procedures ◽  
Simulation Based ◽  
Behavioural Simulation ◽  
Human Participants ◽  
New Policies

Simulation is a technique that evokes or replicates substantial aspects of the real world, in order to experiment with a simplified imitation of an operations system, for the purpose of better understanding and/or improving that system. Simulation provides a safe environment for investigating individual and organisational behaviour and a risk-free testbed for new policies and procedures. Therefore, it can complement or replace direct field observations and trial-and-error approaches, which can be time consuming, costly and difficult to carry out. However, simulation has low adoption as a research and improvement tool in healthcare management and policy-making. The literature on simulation in these fields is dispersed across different disciplinary traditions and typically focuses on a single simulation method. In this article, we examine how simulation can be used to investigate, understand and improve management and policy-making in healthcare organisations. We develop the rationale for using simulation and provide an integrative overview of existing approaches, using examples of in vivo behavioural simulations involving live participants, pure in silico computer simulations and intermediate approaches (virtual simulation) where human participants interact with computer simulations of health organisations. We also discuss the combination of these approaches to organisational simulation and the evaluation of simulation-based interventions.

scholarly journals Methods for the Calculation of Thermoacoustic Stability Margins and Monte Carlo-Free Uncertainty Quantification

2017 ◽  
Author(s):  
Georg A. Mensah ◽  
Luca Magri ◽  
Jonas P. Moeck
Keyword(s):  
Monte Carlo ◽  
Factor Analysis ◽  
Risk Factor ◽  
Uncertainty Quantification ◽  
Frequency Domain ◽  
Gas Turbines ◽  
Network Models ◽  
System Stability ◽  
Risk Factor Analysis ◽  
Model Parameters

Thermoacoustic instabilities are a major threat for modern gas turbines. Frequency-domain based stability methods, such as network models and Helmholtz solvers, are common design tools because they are fast compared to compressible CFD computations. Frequency-domain approaches result in an eigenvalue problem, which is nonlinear with respect to the eigenvalue. Nonlinear functions of the frequency are, for example, the n–τ model, impedance boundary conditions, etc. Thus, the influence of the relevant parameters on mode stability is only given implicitly. Small changes in some model parameters, which are obtained by experiments with some uncertainty, may have a great impact on stability. The assessment of how parameter uncertainties propagate to system stability is therefore crucial for safe gas turbine operation. This question is addressed by uncertainty quantification. A common strategy for uncertainty quantification in thermoacoustics is risk factor analysis. It quantifies the uncertainty of a set of parameters in terms of the probability of a mode to become unstable. One general challenge regarding uncertainty quantification is the sheer number of uncertain parameter combinations to be quantified. For instance, uncertain parameters in an annular combustor might be the equivalence ratio, convection times, geometrical parameters, boundary impedances, flame response model parameters etc. Assessing also the influence of all possible combinations of these parameters on the risk factor is a numerically very costly task. A new and fast way to obtain algebraic parameter models in order to tackle the implicit nature of the eigenfrequency problem is using adjoint perturbation theory. Though adjoint perturbation methods were recently applied to accelerate the risk factor analysis, its potential to improve the theory has not yet been fully exploited. This paper aims to further utilize adjoint methods for the quantification of uncertainties. This analytical method avoids the usual random Monte Carlo simulations, making it particularly attractive for industrial purposes. Using network models and the open-source Helmholtz solver PyHoltz it is also discussed how to apply the method with standard modeling techniques. The theory is exemplified based on a simple ducted flame and a combustor of EM2C laboratory for which experimental validation is available.

Schuldenbremse oder Schuldenschranke für die deutschen Bundesländer?

2008 ◽  
Vol 59 (2) ◽  
Author(s):  
Max Groneck ◽  
Robert C. Plachta
Keyword(s):  
Public Debt ◽  
Simulation Analysis ◽  
Golden Rule ◽  
Simulation Method ◽  
Economic Approach ◽  
Debt Brake ◽  
German Länder

SummaryThis paper studies two alternative budget rules to overcome the shortcomings of the current laws for the German Länder: The Swiss debt brake as well as a version incorporating a golden rule presented by the German Council of Economic Experts. A simulation analysis reveals the necessary consolidation path, the loss of benefits, and the recursive development of public debt. Extending the standard simulation method we present a politico-economic approach considering the budget rules in their full complexity. The Swiss debt brake yields stronger restrictions on public debt than the version incorporating the golden rule. Yet applying the simulation to both Länder and their municipalities leads to contrasting results.

scholarly journals Robust Noise Suppression Technique for a LADAR System via Eigenvalue-Based Adaptive Filtering

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2311
Author(s):  
Xianzhao Xia ◽  
Rui Chen ◽  
Pinquan Wang ◽  
Yiqiang Zhao
Keyword(s):  
Adaptive Filtering ◽  
Noise Level ◽  
Noise Suppression ◽  
Simulation Analysis ◽  
Asymptotic Properties ◽  
Estimation Method ◽  
System Stability ◽  
Noise Level Estimation ◽  
Sample Covariance ◽  
Guided Filtering

The laser detection and ranging system (LADAR) is widely used in various fields that require 3D measurement, detection, and modeling. In order to improve the system stability and ranging accuracy, it is necessary to obtain the complete waveform of pulses that contain target information. Due to the inevitable noise, there are distinct deviations between the actual and expected waveforms, so noise suppression is essential. To achieve the best effect, the filters’ parameters that are usually set as empirical values should be adaptively adjusted according to the different noise levels. Therefore, we propose a novel noise suppression method for the LADAR system via eigenvalue-based adaptive filtering. Firstly, an efficient noise level estimation method is developed. The distributions of the eigenvalues of the sample covariance matrix are analyzed statistically after one-dimensional echo data are transformed into matrix format. Based on the boundedness and asymptotic properties of the noise eigenvalue spectrum, an estimation method for noise variances in high dimensional settings is proposed. Secondly, based on the estimated noise level, an adaptive guided filtering algorithm is designed within the gradient domain. The optimized parameters of the guided filtering are set according to an estimated noise level. Through simulation analysis and testing experiments on echo waves, it is proven that our algorithm can suppress the noise reliably and has advantages over the existing relevant methods.

scholarly journals Y25 freight car bogie models properties analysis by means of computer simulations

2018 ◽  
Vol 157 ◽  
pp. 03014 ◽  
Author(s):  
Tomáš Lack ◽  
Juraj Gerlici
Keyword(s):  
Tangential Stress ◽  
Computer Simulations ◽  
Simulation Analysis ◽  
The Other ◽  
Bogie Frame ◽  
Friction Dampers ◽  
Research Results ◽  
Railway Wagon ◽  
Freight Car ◽  
Railway Wheels

The article deals with the results of the simulation analysis of a railway wagon bogie model. We analysed four freight wagon bogie variants for its dynamics properties research. The bogie models correspond in general to the Y25 bogie concept. The models were created in SIMPACK software enhanced by the RAIL module. From the research results depicted in the graphs we found out, that the newly designed bogie variant gives the best results when compared to the other analysed versions. The newly designed model consists of a standard Y25 bogie frame with two Lenoire friction dampers. This bogie is equipped with longitudinal linkages on both sides. These linkages are completed with a radial torsion binding, torsion rod, between side bogie parts. The contact of railway wheels and rails generates active forces affecting the surface contact, affecting the size of the normal and tangential stress, wear surfaces of the wheel/rail, or directly the size of the derailment.

Controller Designs for a Class of Polynomial Fuzzy Models

2015 ◽  
Vol 19 (6) ◽  
pp. 796-803 ◽  
Author(s):  
Hugang Han ◽  
◽  
Yuta Higaki ◽  
Keyword(s):  
Control System ◽  
Computer Simulations ◽  
Disturbance Observer ◽  
Point Of View ◽  
Polynomial Model ◽  
The Other ◽  
System Stability ◽  
Control Performance ◽  
Fuzzy Models ◽  
Better Than

This paper proposes two polynomial fuzzy controllers in the context of the fuzzy polynomial model with a so-called lumped disturbance. One, called regular controller, is designed only based on the control system stability, while the other, called controller with disturbance observer, is designed on the basis of both control system stability and a disturbance observer proposed in this paper. Though both controllers are able to stabilize the control system, computer simulations conclude that the latter is better than the former from the point of view of the control performance when it comes to the lumped disturbance in the system concerned.

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