scholarly journals Modeling and analysis of a mistuned fan blisk

2021 ◽  
Vol 9 ◽  
Author(s):  
Muhammad Usman Bashir ◽  
◽  
Anees Ur Rehman ◽  
Aashir Waleed ◽  
Umar Siddique Virk ◽  
...  
Keyword(s):  
Vital Role ◽  
Model Parameters ◽  
Jet Engines ◽  
Bladed Disks ◽  
Modal Assurance Criterion ◽  
Modeling And Analysis ◽  
Compressor Impeller ◽  
Vibrational Characteristics ◽  
Turbine Blisk ◽  
Critical Components

Turbomachinery has a vital role in the industrial engineering and the bladed disks such as; compressor, impeller pumps, turbine generator and jet engines are the critical components of turbomachinery. This work is focused on the “mistuning effect” of bladed disks of a turbine, which creates the lack of symmetry and ultimately damages the turbine blade. In order to completely understand the severity of the damage caused by the mistuning effect on the turbine disk, the study and analysis of the model parameters is very important. This work provides an insight to the various effects caused by the presence of crack and mistuning levels, in the mistuned turbine blisk, by using smeared material properties and modal assurance criterion (MAC) techniques. Moreover, a mistuned blisk model with four cracks (at various locations and different depth levels) has been developed and compared with the tuned blisk model, in order to determine the severity of damage occurred. The MAC results indicate that the severity of damage may vary depending on the location and depth of the crack and mistuning may alter the dynamic and vibrational characteristics of the structure.

Investigating the vibrational behaviour of a rotating two-blade propeller by using a self-tracking method

2018 ◽  
Vol 233 (3) ◽  
pp. 835-847 ◽  
Author(s):  
Mohammad-Reza Ashory ◽  
Farhad Talebi ◽  
Heydar R Ghadikolaei ◽  
Morad Karimpour
Keyword(s):  
Natural Frequency ◽  
Measurement Errors ◽  
Mode Shapes ◽  
Model Parameters ◽  
Test Results ◽  
Modal Assurance Criterion ◽  
Tracking Method ◽  
Strong Resemblance ◽  
Test Scenarios ◽  
Good Agreement

This study investigated the vibrational behaviour of a rotating two-blade propeller at different rotational speeds by using self-tracking laser Doppler vibrometry. Given that a self-tracking method necessitates the accurate adjustment of test setups to reduce measurement errors, a test table with sufficient rigidity was designed and built to enable the adjustment and repair of test components. The results of the self-tracking test on the rotating propeller indicated an increase in natural frequency and a decrease in the amplitude of normalized mode shapes as rotational speed increases. To assess the test results, a numerical model created in ABAQUS was used. The model parameters were tuned in such a way that the natural frequency and associated mode shapes were in good agreement with those derived using a hammer test on a stationary propeller. The mode shapes obtained from the hammer test and the numerical (ABAQUS) modelling were compared using the modal assurance criterion. The examination indicated a strong resemblance between the hammer test results and the numerical findings. Hence, the model can be employed to determine the other mechanical properties of two-blade propellers in test scenarios.

Hierarchical Bayesian Parameter Estimation for Modeling and Analysis of User Affective Influence

2013 ◽  
Author(s):  
Feng Zhou ◽  
Jianxin (Roger) Jiao
Keyword(s):  
Decision Making ◽  
Interior Design ◽  
Computational Models ◽  
Human Perception ◽  
Model Parameters ◽  
Hierarchical Bayesian ◽  
Affective States ◽  
Modeling And Analysis ◽  
Human Decision

Traditional user experience (UX) models are mostly qualitative in terms of its measurement and structure. This paper proposes a quantitative UX model based on cumulative prospect theory. It takes a decision making perspective between two alternative design profiles. However, affective elements are well-known to have influence on human decision making, the prevailing computational models for analyzing and simulating human perception on UX are mainly cognition-based models. In order to incorporate both affective and cognitive factors in the decision making process, we manipulate the parameters involved in the cumulative prospect model to show the affective influence. Specifically, three different affective states are induced to shape the model parameters. A hierarchical Bayesian model with a technique called Markov chain Monte Carlo is used to estimate the parameters. A case study of aircraft cabin interior design is illustrated to show the proposed methodology.

scholarly journals Small Signal Modeling and Analysis of a Dual Input Interleaved DC-DC Converter

2020 ◽  
Vol 8 (6) ◽  
pp. 5402-5411
Keyword(s):  
Performance Analysis ◽  
Closed Loop ◽  
Dynamic Performance ◽  
Energy System ◽  
Vital Role ◽  
Performance Comparison ◽  
Small Signal ◽  
Solar Pv ◽  
Modeling And Analysis ◽  
Hybrid Energy

The idea of DC-DC converter with multi-input is yet to attain a vital role in the field of 'hybrid energy system (HES)' integration and electric vehicle applications. So, the analysis of the dynamic behavior of the multi input converters is crucial in designing a proper controller to achieve a stable performance. This paper reports a 'small signal model (SSM)' and the performance analysis of a 'dual-input DC-DC converter (DIC)'. The parasitic resistances of capacitor and inductor are considered in the modelling. The significant transfer function (TF)s are derived with the help of the SSM, and the Bode plots for the TFs have been obtained. The performance analysis shows that the derived TFs allow better closed loop performance of the system. The simulation of the DIC converter in MATLAB/ Simulink® has been carried out and the simulation waveforms are presented. A hardware setup of the DIC converter is fabricated and experimented in the laboratory. The dynamic performance of the DIC is analyzed under the variations in the source and load conditions. The presented converter with a closed loop controller can be used in the applications to formulate a HES with solar-PV, battery, fuel cell, etc. Also the performance comparison of the DIC converter has been performed with other reported converters which shows that the DIC converter has higher efficiency and several other potential merits.

scholarly journals A Flexible Data-Driven Framework for COVID-19 Case Forecasting Deployed in a Developing-world Public Health Setting

2021 ◽  
Author(s):  
Sansiddh Jain ◽  
Avtansh Tiwari ◽  
Nayana Bannur ◽  
Ayush Deva ◽  
Siddhant Shingi ◽  
...  
Keyword(s):  
Bayesian Model Averaging ◽  
Model Averaging ◽  
Ground Truth ◽  
Model Parameters ◽  
Forecasting System ◽  
Critical Components ◽  
Approximate Bayesian ◽  
Operational Constraints ◽  
Best Fit ◽  
Public Health Setting

Forecasting infection case counts and estimating accurate epidemiological parameters are critical components of managing the response to a pandemic. This paper describes a modular, extensible framework for a COVID-19 forecasting system, primarily deployed in Mumbai and Jharkhand, India. We employ a variant of the SEIR compartmental model motivated by the nature of the available data and operational constraints. We estimate best-fit parameters using sequential Model-Based Optimization (SMBO) and describe the use of a novel, fast, and approximate Bayesian model averaging method (ABMA) for parameter uncertainty estimation that compares well with a more rigorous Markov Chain Monte Carlo (MCMC) approach in practice. We address on-the-ground deployment challenges such as spikes in the reported input data using a novel weighted smooth-ing method. We describe extensive empirical analyses to evaluate the accuracy of our method on ground truth as well as against other state-of-the-art approaches. Finally, we outline deployment lessons and describe how inferred model parameters were used by government partners to interpret the state of the epidemic and how model forecasts were used to estimate staffing and planning needs essential for addressing COVID-19 hospital burden.

scholarly journals Modeling and analysis of the impacts of jet lag on circadian rhythm and its role in tumor growth

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4877 ◽  
Author(s):  
Azka Hassan ◽  
Jamil Ahmad ◽  
Hufsah Ashraf ◽  
Amjad Ali
Keyword(s):  
Circadian Rhythms ◽  
Circadian Clock ◽  
Clock Genes ◽  
Damage Control ◽  
Vital Role ◽  
Biochemical Networks ◽  
Jet Lag ◽  
Peripheral Tissues ◽  
Modeling And Analysis ◽  
Circadian Clock Proteins

Circadian rhythms maintain a 24 h oscillation pattern in metabolic, physiological and behavioral processes in all living organisms. Circadian rhythms are organized as biochemical networks located in hypothalamus and peripheral tissues. Rhythmicity in the expression of circadian clock genes plays a vital role in regulating the process of cell division and DNA damage control. The oncogenic protein, MYC and the tumor suppressor, p53 are directly influenced by the circadian clock. Jet lag and altered sleep/wake schedules prominently affect the expression of molecular clock genes. This study is focused on developing a Petri net model to analyze the impacts of long term jet lag on the circadian clock and its probable role in tumor progression. The results depict that jet lag disrupts the normal rhythmic behavior and expression of the circadian clock proteins. This disruption leads to persistent expression of MYC and suppressed expression of p53. Thus, it is inferred that jet lag altered circadian clock negatively affects the expressions of cell cycle regulatory genes and contribute in uncontrolled proliferation of tumor cells.

Constitutive Modeling of Corneal Tissue: Influence of Three-Dimensional Collagen Fiber Microstructure

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Shuolun Wang ◽  
Hamed Hatami-Marbini
Keyword(s):  
Extracellular Matrix ◽  
Constitutive Modeling ◽  
Mechanical Response ◽  
Thickness Distribution ◽  
Three Dimensional ◽  
Vital Role ◽  
Collagen Fibrils ◽  
Model Parameters ◽  
Corneal Tissue ◽  
Numerical Predictions

Abstract The cornea, the transparent tissue in the front of the eye, along with the sclera, plays a vital role in protecting the inner structures of the eyeball. The precise shape and mechanical strength of this tissue are mostly determined by the unique microstructure of its extracellular matrix. A clear picture of the 3D arrangement of collagen fibrils within the corneal extracellular matrix has recently been obtained from the secondary harmonic generation images. However, this important information about the through-thickness distribution of collagen fibrils was seldom taken into account in the constitutive modeling of the corneal behavior. This work creates a generalized structure tensor (GST) model to investigate the mechanical influence of collagen fibril through-thickness distribution. It then uses numerical simulations of the corneal mechanical response in inflation experiments to assess the efficacy of the proposed model. A parametric study is also done to investigate the influence of model parameters on numerical predictions. Finally, a brief comparison between the performance of this new constitutive model and a recent angular integration (AI) model from the literature is given.

Modeling and Analysis of Ice Shed in Multistage Compressor of Jet Engines

2014 ◽  
Author(s):  
Reema Kundu ◽  
J V R Prasad ◽  
Rajkeshar Singh ◽  
Swati Saxena ◽  
Andy Breeze-Stringfellow ◽  
...  
Keyword(s):  
Jet Engines ◽  
Modeling And Analysis ◽  
Multistage Compressor

Modeling and Analysis of Elastoplastic Impacts on Supported Composites

2011 ◽  
Vol 471-472 ◽  
pp. 367-372 ◽  
Author(s):  
Majed A. Majeed ◽  
Ahmet S. Yigit ◽  
Andreas P. Christoforou
Keyword(s):  
Isotropic Material ◽  
Composite Layer ◽  
Transversely Isotropic ◽  
Material Behavior ◽  
Model Parameters ◽  
Fe Model ◽  
Transversely Isotropic Material ◽  
Spherical Object ◽  
Modeling And Analysis ◽  
Plastic Indentation

This paper presents an elastoplastic impact model for a spherical object impacting a supported composite layer or a half-space. The model utilizes a contact law that has been developed based on elastic-plastic and fully plastic indentation theories. For an impact event, the model parameters can easily be obtained analytically, computationally using Finite Elements (FE), and from experiments, by assuming transversely isotropic material behavior. Simulations are compared to those from a nonlinear FE model developed in ABAQUS, and to limited experimental data, with excellent results.

scholarly journals Simulation of lead Antimony Alloy Solidification and its Experimental Validation

2020 ◽  
Vol 9 (4) ◽  
pp. 68-72
Keyword(s):  
Direct Method ◽  
Research Work ◽  
Casting Process ◽  
Vital Role ◽  
Simulation Software ◽  
Temperature History ◽  
Alloy Solidification ◽  
Modeling And Analysis ◽  
Transient Thermal ◽  
Antimony Alloy

The solidification of metals continues to be a phenomenon of great interest to physicists, metallurgists, casting engineers, and software developers. It is a non-linear transient phenomenon, posing a challenge in terms of modeling and analysis. During the solidification of a casting in a mould, the heat-transfer between the casting and the mould plays a vital role. This paper attempts to study heat flow within the casting, as well as from the casting to the mould, and finally obtains the temperature history of some points inside the casting. The most important instant of time is when the hottest region inside the casting is solidifying. ProCAST software has been used to obtain the temperature distribution in the casting process by performing Transient Thermal Analysis. In this research work, solidification of lead-2wt%antimony alloy has been carried out in the different sizes of metallic mold to predict the formation of shrinkage during solidification. Theoretical results have been validated experimentally for a particular case of lead-2wt%antimony alloy solidification. Results obtained by simulation software are compared with the experimental reading of temperature and found to be in good agreement. Voids appeared at the top and isolated area of castings for the defect-free direct method used in this study.

scholarly journals Mathematical Modeling and Analysis of an Alcohol Drinking Model with the Influence of Alcohol Treatment Centers

2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Bouchaib Khajji ◽  
Abderrahim Labzai ◽  
Omar Balatif ◽  
Mostafa Rachik
Keyword(s):  
Alcohol Drinking ◽  
Addiction Treatment ◽  
Reproduction Number ◽  
Dynamical Behavior ◽  
Model Parameters ◽  
Asymptotically Stable ◽  
Globally Asymptotically Stable ◽  
Modeling And Analysis ◽  
Private And Public ◽  
The Stability

In this paper, we present a continuous mathematical model PMHTrTpQ of alcohol drinking with the influence of private and public addiction treatment centers. We study the dynamical behavior of this model and we discuss the basic properties of the system and determine its basic reproduction number R0. We also study the sensitivity analysis of model parameters to know the parameters that have a high impact on the reproduction number R0. The stability analysis of the model shows that the system is locally as well as globally asymptotically stable at drinking-free equilibrium E0 when R0≤1. When R0>1, drinking present equilibrium E∗ exists and the system is locally as well as globally asymptotically stable at alcohol present equilibrium E∗.

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