scholarly journals Probabilistic model for flexural strength of carbon nanotube reinforced cement-based materials

2020 ◽  
Author(s):  
Mahyar Ramezani ◽  
Young Hoon Kim ◽  
Zhihui Sun
Keyword(s):  
Flexural Strength ◽  
Probabilistic Model ◽  
Probabilistic Approach ◽  
Cementitious Materials ◽  
Model Parameters ◽  
Bonding Mechanism ◽  
Deterministic Models ◽  
Probability Estimates ◽  
Proposed Model ◽  
Dispersion Quality

The bond between carbon nanotubes (CNTs) and cementitious materials is the key characteristic for predicting the flexural strength. However, CNT dispersion quality may change the bonding mechanism. A probabilistic approach can benefit the deterministic models to capture the uncertainties affecting these characteristics. This study proposes a probabilistic model using the Kelly‐Tyson theory to predict the flexural strength of CNT‐cement nanocomposites. The proposed model considers the effects of experimental variables on CNT dispersion quality, bonding mechanism and the flexural strength. To this end, a Bayesian methodology is employed to calibrate the unknown model parameters and various sources of uncertainty using extensive test data. The model is then used to identify the optimum ranges of variables to maximize the flexural strength through computing the failure probability which is defined as the probability of not meeting certain strength requirements (herein, 50% increase compared with the control). The model suggests that CNT aspect ratio ranges from 400 to 800 and concentration between 0.08 and 0.18 c‐wt% yields the highest flexural strength. Finally, the effect of changes in experimental variables on the probability estimates is examined using sensitivity and importance measures. The analysis reveals that the proposed model can capture the experimentally observed trends with reasonable accuracy. For example, the importance of age increases as CNT concentration increases.

scholarly journals Probabilistic model for flexural strength of cementitious materials containing CNTs

2020 ◽  
Author(s):  
Mahyar Ramezani ◽  
Young Hoon Kim ◽  
Zhihui Sun
Keyword(s):  
Flexural Strength ◽  
Probabilistic Model ◽  
Probabilistic Approach ◽  
Model Development ◽  
Cementitious Materials ◽  
Model Parameters ◽  
Test Results ◽  
Robust Model ◽  
Proposed Model ◽  
Dispersion Quality

The bond between carbon nanotubes (CNTs) and cementitious materials is the key characteristic for predicting the flexural strength. However, the dispersion quality dominantly changes bond mechanisms. A probabilistic approach can benefit a robust model development to capture various relations. This study proposes a probabilistic model based on the deterministic Kelly-Tyson theory to predict the flexural strength of CNT reinforced cementitious materials. The proposed model considers the influences of multiple experimental variables and their interactions on CNT dispersion quality and the flexural strength. A Bayesian methodology is adopted to calibrate the unknown model parameters and their statistical uncertainty using extensive experimental test results from the literature including the authors’ work. The proposed model can be reliably used to predict the flexural strength with reasonable accuracy.

scholarly journals ON THE ISSUE OF PLANNING SOWING AGRICULTURAL CROPS WITH THE MINIMUM RISK UNDER THE PRESENCE OF VARIOUS AGROCLIMATIC CONDITIONS

2021 ◽  
Vol 1 ◽  
pp. 72-83
Author(s):  
Sharif E. Guseynov ◽  
Sergey Matyukhin ◽  
Misir J. Mardanov ◽  
Jekaterina V. Aleksejeva ◽  
Olga Sidorenko
Keyword(s):  
Mathematical Models ◽  
Analytical Solutions ◽  
Probabilistic Model ◽  
Probabilistic Approach ◽  
Minimal Risk ◽  
Agricultural Crops ◽  
Deterministic Approach ◽  
Deterministic Models ◽  
Minimum Risk ◽  
Sown Area

The present paper deals with one problem of quantitative controlling the seeding of the sown area by agricultural crops in different agroclimatic conditions. The considered problem is studied from the standpoint of three strategies: from the seeding planning perspective aiming at minimal risk associated with possible unfavourable agroclimatic conditions (a probabilistic approach is used); from the perspective of obtaining the maximum crops sales profit (a deterministic approach is used); from the perspective of obtaining the maximum crops harvest. For the considered problem, mathematical models are constructed (one probabilistic model and two deterministic models, respectively), their analytical solutions are found, and then, using a specific example, the application of the constructed and solved mathematical models is illustrated as well as the obtained numerical results are analysed..

scholarly journals Elastic modulus formulation of cementitious materials incorporating carbon nanotubes: Probabilistic approach

2020 ◽  
Author(s):  
Mahyar Ramezani ◽  
Young Hoon Kim ◽  
Zhihui Sun
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Modulus ◽  
Probabilistic Approach ◽  
Cementitious Materials ◽  
Matrix Composition ◽  
Extensive Literature ◽  
Selection Procedures ◽  
Sources Of Uncertainty ◽  
Proposed Model ◽  
High Degree

Carbon nanotube (CNT) is one of the most promising nanomaterials to increase the elastic modulus of cementitious composites. However, CNT characteristics, dispersion procedure, and matrix composition/hydration are critical and correlated with a high degree of uncertainty in achieving a desirable performance. This paper proposes a mechanics-based model to predict the elastic modulus of CNT reinforced cementitious materials based on the Halpin-Tsai equation. The current study employs a probabilistic approach to consider the influences of multiple experimental variables and various sources of uncertainty associated with them. To this end, first, a Bayesian methodology is adopted to perform the model validation, evaluation, and selection procedures using extensive literature test data. Then, the optimum rangesof variables are found to maximize the chance of achieving a certain target modulus (herein, 50% more than control) using a reliability analysis. The proposed model suggests that the highest elastic modulus is achieved when using CNT aspect ratio ranges from 400 to 800 and concentration between 0.08 and 0.18 c-wt%. Also, the experimentally observed elastic modulus and the proposed probabilistic model exhibit a similar trend. For example, the importance of hydration age increases as CNT concentrationincreases. Finally, the proposed model can be used to reliably predict the elastic modulus, guiding futureresearchers to design more efficiently.

scholarly journals A probabilistic model for discretionary lane change proposals in highway driving situations

2021 ◽  
Author(s):  
Manuel Schmidt ◽  
Christian Wissing ◽  
Till Nattermann ◽  
Torsten Bertram
Keyword(s):  
Probabilistic Model ◽  
Driving Simulator ◽  
Probabilistic Approach ◽  
Real Data ◽  
Model Parameters ◽  
Lane Change ◽  
Test Vehicle ◽  
Automated Vehicle ◽  
Preceding Vehicle ◽  
Simulator Study

AbstractThis contribution presents a novel probabilistic approach for the generation of discretionary lane change proposals with a focus on highway driving situations. The developed model is based on the quantification of the utility of driving lanes. It generates a lane change proposal if the current driving lane is unsatisfactory in the sense that the desired velocity of the automated vehicle is undershot because of a slow preceding vehicle. A driving simulator study was conducted to create a dataset for the optimization of the model parameters. The optimization goal is to accurately match the timings of the lane change intentions of all participants. Finally, the applicability of the model is shown on real data from a test vehicle.

In-Plane Flexible Ring Tire Model—Part 1: Modeling and Parameter Identification

2018 ◽  
Vol 46 (3) ◽  
pp. 174-219 ◽  
Author(s):  
Bin Li ◽  
Xiaobo Yang ◽  
James Yang ◽  
Yunqing Zhang ◽  
Zeyu Ma
Keyword(s):  
Static Load ◽  
Model Parameters ◽  
Tire Model ◽  
Test Results ◽  
Lumped Mass ◽  
Virtual Test ◽  
Proposed Model ◽  
Particle Swarm Method ◽  
Vehicle Dynamic Simulation ◽  
Flexible Ring

ABSTRACT The tire model is essential for accurate and efficient vehicle dynamic simulation. In this article, an in-plane flexible ring tire model is proposed, in which the tire is composed of a rigid rim, a number of discretized lumped mass belt points, and numerous massless tread blocks attached on the belt. One set of tire model parameters is identified by approaching the predicted results with ADAMS® FTire virtual test results for one particular cleat test through the particle swarm method using MATLAB®. Based on the identified parameters, the tire model is further validated by comparing the predicted results with FTire for the static load-deflection tests and other cleat tests. Finally, several important aspects regarding the proposed model are discussed.

EXPONENTIATED HALF-LOGISTIC LOMAX DISTRIBUTION WITH PROPERTIES AND APPLICATION

2019 ◽  
Vol XVI (2) ◽  
pp. 1-11
Author(s):  
Farrukh Jamal ◽  
Hesham Mohammed Reyad ◽  
Soha Othman Ahmed ◽  
Muhammad Akbar Ali Shah ◽  
Emrah Altun
Keyword(s):  
Real Data ◽  
Continuous Model ◽  
Model Parameters ◽  
Data Set ◽  
Lomax Distribution ◽  
Mathematical Properties ◽  
Proposed Model ◽  
Probability Weighted Moment ◽  
Record Statistics ◽  
Maximum Likelihood Criterion

A new three-parameter continuous model called the exponentiated half-logistic Lomax distribution is introduced in this paper. Basic mathematical properties for the proposed model were investigated which include raw and incomplete moments, skewness, kurtosis, generating functions, Rényi entropy, Lorenz, Bonferroni and Zenga curves, probability weighted moment, stress strength model, order statistics, and record statistics. The model parameters were estimated by using the maximum likelihood criterion and the behaviours of these estimates were examined by conducting a simulation study. The applicability of the new model is illustrated by applying it on a real data set.

scholarly journals A General Temperature-Dependent Stress–Strain Constitutive Model for Polymer-Bonded Composite Materials

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1393
Author(s):  
Xiaochang Duan ◽  
Hongwei Yuan ◽  
Wei Tang ◽  
Jingjing He ◽  
Xuefei Guan
Keyword(s):  
Composite Materials ◽  
Constitutive Model ◽  
Model Parameters ◽  
Temperature Dependent ◽  
Stress Strain ◽  
Proposed Model ◽  
Single Temperature ◽  
Testing Data ◽  
Bonded Composite ◽  
Tension And Compression

This study develops a general temperature-dependent stress–strain constitutive model for polymer-bonded composite materials, allowing for the prediction of deformation behaviors under tension and compression in the testing temperature range. Laboratory testing of the material specimens in uniaxial tension and compression at multiple temperatures ranging from −40 ∘C to 75 ∘C is performed. The testing data reveal that the stress–strain response can be divided into two general regimes, namely, a short elastic part followed by the plastic part; therefore, the Ramberg–Osgood relationship is proposed to build the stress–strain constitutive model at a single temperature. By correlating the model parameters with the corresponding temperature using a response surface, a general temperature-dependent stress–strain constitutive model is established. The effectiveness and accuracy of the proposed model are validated using several independent sets of testing data and third-party data. The performance of the proposed model is compared with an existing reference model. The validation and comparison results show that the proposed model has a lower number of parameters and yields smaller relative errors. The proposed constitutive model is further implemented as a user material routine in a finite element package. A simple structural example using the developed user material is presented and its accuracy is verified.

scholarly journals Flexural behavior of composite structural insulated panels with magnesium oxide board facings

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Łukasz Smakosz ◽  
Ireneusz Kreja ◽  
Zbigniew Pozorski
Keyword(s):  
Magnesium Oxide ◽  
Material Model ◽  
Expanded Polystyrene ◽  
Flexural Behavior ◽  
Joint Analysis ◽  
Model Parameters ◽  
Fe Model ◽  
Computational Results ◽  
Four Point Bending ◽  
Proposed Model

Abstract The current report is devoted to the flexural analysis of a composite structural insulated panel (CSIP) with magnesium oxide board facings and expanded polystyrene (EPS) core, that was recently introduced to the building industry. An advanced nonlinear FE model was created in the ABAQUS environment, able to simulate the CSIP’s flexural behavior in great detail. An original custom code procedure was developed, which allowed to include material bimodularity to significantly improve the accuracy of computational results and failure mode predictions. Material model parameters describing the nonlinear range were identified in a joint analysis of laboratory tests and their numerical simulations performed on CSIP beams of three different lengths subjected to three- and four-point bending. The model was validated by confronting computational results with experimental results for natural scale panels; a good correlation between the two results proved that the proposed model could effectively support the CSIP design process.

scholarly journals Mixture of Inverse Weibull and Lognormal Distributions: Properties, Estimation, and Illustration

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
K. S. Sultan ◽  
A. S. Al-Moisheer
Keyword(s):  
Information Matrix ◽  
Real Data ◽  
Likelihood Method ◽  
Model Parameters ◽  
Component Mixture ◽  
Data Set ◽  
Hazard Functions ◽  
Lognormal Distributions ◽  
Proposed Model ◽  
Estimation Of Model Parameters

We discuss the two-component mixture of the inverse Weibull and lognormal distributions (MIWLND) as a lifetime model. First, we discuss the properties of the proposed model including the reliability and hazard functions. Next, we discuss the estimation of model parameters by using the maximum likelihood method (MLEs). We also derive expressions for the elements of the Fisher information matrix. Next, we demonstrate the usefulness of the proposed model by fitting it to a real data set. Finally, we draw some concluding remarks.

A robust possibilistic programming model for production-routing problem in a three-echelon supply chain

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Ali Beheshtinia ◽  
Narjes Salmabadi ◽  
Somaye Rahimi
Keyword(s):  
Supply Chain ◽  
Real Life ◽  
Model Parameters ◽  
Pickup And Delivery ◽  
Distribution Centers ◽  
Routing Problem ◽  
Remarkable Feature ◽  
Content Type ◽  
Proposed Model ◽  
Production Routing

Purpose This paper aims to provide an integrated production-routing model in a three-echelon supply chain containing a two-layer transportation system to minimize the total costs of production, transportation, inventory holding and expired drugs treatment. In the proposed problem, some specifications such as multisite manufacturing, simultaneous pickup and delivery and uncertainty in parameters are considered. Design/methodology/approach At first, a mathematical model has been proposed for the problem. Then, one possibilistic model and one robust possibilistic model equivalent to the initial model are provided regarding the uncertain nature of the model parameters and the inaccessibility of their probability function. Finally, the performance of the proposed model is evaluated using the real data collected from a pharmaceutical production center in Iran. The results reveal the proper performance of the proposed models. Findings The results obtained from applying the proposed model to a real-life production center indicated that the number of expired drugs has decreased because of using this model, also the costs of the system were reduced owing to integrating simultaneous drug pickup and delivery operations. Moreover, regarding the results of simulations, the robust possibilistic model had the best performance among the proposed models. Originality/value This research considers a two-layer vehicle routing in a production-routing problem with inventory planning. Moreover, multisite manufacturing, simultaneous pickup of the expired drugs and delivery of the drugs to the distribution centers are considered. Providing a robust possibilistic model for tackling the uncertainty in demand, costs, production capacity and drug expiration costs is considered as another remarkable feature of the proposed model.

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