Development of an aid tool for evaluation of unsaturated soils permeability

2019 ◽  
Vol 16 (2) ◽  
pp. 322-330
Author(s):  
Leila Mechkarini ◽  
Tahar Messafer ◽  
Abderrahim Bali ◽  
Kamel Silhadi
Keyword(s):  
Unsaturated Soils ◽  
Prediction Models ◽  
Laboratory Data ◽  
Degree Of Saturation ◽  
Content Type ◽  
Unsaturated Permeability ◽  
Knowledge Structuring ◽  
The Mathematical Model ◽  
Bibliographic Study ◽  
Help System

Purpose Prediction models for the unsaturated permeability proposed in the literature are numerous. However, a model may give a good result for a sample of a given soil when it may give a bad result for another sample belonging to the same type of soil. This showed that the choice of a model to complete the permeability curve in the unsaturated state is complex. To facilitate such studies, this paper aims to present a help system capable of defining the mathematical model to the user that best represents the permeability of the soil. Design/methodology/approach The authors have detailed the difficulties in determining the correct value of kuns from a thorough bibliographic study. To develop this idea, the authors took real examples, to which they applied mathematical models and then compared their results with those of the bibliographic study. Knowledge structuring in the form of classes, rules and functions. Implementation of the data in generator of help system Kappa-pc. validation of results. Findings An aid tool was developed for the evaluation of unsaturated soils permeability using Brooks and Corey (1964) and Leong and Rahardjo (1997) models, which are known for their effectiveness and ease of application. This system will also evaluate these two methods using estimation models of saturated permeability [Dane and Pocket (1992), Terzaghi (1981) and laboratory data]. This system allows the evaluation of unsaturated permeability by the aforementioned two models, makes comparison between these two models, classifies them and proposes the model presenting the best result. Originality/value This aid system is able to compare results of different models of prediction of the hydraulic conductivity of unsaturated soils according to several criteria (suction, degree of saturation, plasticity index, models of estimation of the permeability to the soil, saturated state, particle size, etc.). It can also deduce the model that best adapts to a given soil. This aid system will be of great use for geotechnical engineers and researchers in the field.

A bibliographic study on big data: concepts, trends and challenges

2017 ◽  
Vol 23 (3) ◽  
pp. 555-573 ◽  
Author(s):  
Deepa Mishra ◽  
Zongwei Luo ◽  
Shan Jiang ◽  
Thanos Papadopoulos ◽  
Rameshwar Dubey
Keyword(s):  
Big Data ◽  
Citation Analysis ◽  
Design Methodology ◽  
Future Directions ◽  
Content Type ◽  
Current Trends ◽  
Bibliographic Study

Purpose The purpose of paper is twofold. First, it provides a consolidated overview of the existing literature on “big data” and second, it presents the current trends and opens up various future directions for researchers who wish to explore and contribute in this rapidly evolving field. Design/methodology/approach To achieve the objective of this study, the bibliographic and network techniques of citation and co-citation analysis was adopted. This analysis involved an assessment of 57 articles published over a period of five years (2011-2015) in ten selected journals. Findings The findings reveal that the number of articles devoted to the study of “big data” has increased rapidly in recent years. Moreover, the study identifies some of the most influential articles of this area. Finally, the paper highlights the new trends and discusses the challenges associated with big data. Research limitations/implications This study focusses only on big data concepts, trends, and challenges and excludes research on its analytics. Thus, researchers may explore and extend this area of research. Originality/value To the knowledge of the authors, this is the first study to review the literature on big data by using citation and co-citation analysis.

Capillary-based effective stress formulation for predicting shear strength of unsaturated soils

2015 ◽  
Vol 52 (12) ◽  
pp. 2067-2076 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Marc Lebeau
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Unsaturated Soils ◽  
Water Retention ◽  
Adsorbed Water ◽  
Soil Strength ◽  
Liquid Films ◽  
Degree Of Saturation ◽  
Stress Parameter ◽  
Effective Stress Parameter

A number of investigations have shown that the shear strength of unsaturated soils can be defined in terms of effective stress. The difficulty in this approach lies in quantifying the effective stress parameter, or Bishop’s parameter. Although often set equal to the degree of saturation, it has recently been suggested that the effective stress parameter should be related to an effective degree of saturation, which defines the fraction of water that contributes to soil strength. A problematic element in this approach resides in differentiating the water that contributes to soil strength from that which does not contribute to soil strength. To address this difficulty, the paper uses theoretical considerations and experimental observations to partition the water retention function into capillary and adsorptive components. Given that the thin liquid films of adsorbed water should not contribute to effective stress, the effective stress parameter is solely related to the capillary component of water retention. In sample calculations, this alternative effective stress parameter provided very good agreement with experimental data of shear strength for a variety of soil types.

Fractional order plasma modeling based on linear polarization of LASER light: an Atangana–Baleanu Caputo approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tamour Zubair ◽  
Muhammad Usman ◽  
Tiao Lu
Keyword(s):  
Fractional Order ◽  
Numerical Algorithm ◽  
Laser Light ◽  
Spectral Estimation ◽  
Initial Perturbation ◽  
Physical Analysis ◽  
Content Type ◽  
Specific Geometry ◽  
The Mathematical Model ◽  
Time Evaluation

PurposeThe purpose of this offered research is to articulate a multifaceted kind of highly unstable initial perturbation and further analyze the performance of the plasma particles for time-fractional order evaluation.Design/methodology/approachFor this purpose, the authors designed specific geometry and further interpreted it into the mathematical model using the concepts of the Vlasov Maxwell system. The suggested algorithm is based on the finite-difference and spectral estimation philosophy. The management of time and memory in generic code for computational purposes is also discussed.FindingsThe main purpose is to analyze the fractional behavior of plasma particles and also the capability of the suggested numerical algorithm. Due to initial perturbations, there are a lot of sudden variations that occurred in the formulated system. Graphical behavior shows that SR parameter produces devastation as compared to others. The variation of fractional parameter between the defend domain demonstrates the hidden pictures of plasma particles. The design scheme is efficient, convergent and has the capability to cover the better physics of the problem.Practical implicationsPlasma material is commonly used in different areas of science. Therefore, in this paper, the authors increase the capability of the mathematical plasma model with specific geometry, and further suitable numerical algorithm is suggested with detailed physical analysis of the outcomes. The authors gave a new direction to study the performance of plasma particles under the influence of LASER light.Originality/valueIn the recent era, science has produced a lot of advancements to study and analyze the physical natural process, which exist everywhere in the real word. On behalf of this current developments, it is now insufficient to study the first-order time evaluation of the plasma particles. One needs to be more precise and should move toward the bottomless state of it, that is, macroscopic and microscopic time-evaluation scales, and it is not wrong to say that there exits a huge gap, to study the time evaluation in this discussed manner. The presented study is entirely an advanced and efficient way to investigate the problem into the new directions. The capability of the proposed algorithm and model with fractional concepts can fascinate the reader to extend to the other dimensions.

A review of literature on risk prediction tools for hospital readmissions in older adults

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Michelle Louise Gatt ◽  
Maria Cassar ◽  
Sandra C. Buttigieg
Keyword(s):  
Risk Prediction ◽  
Prediction Models ◽  
Hospital Readmissions ◽  
Predictive Ability ◽  
Chronic Obstructive ◽  
Risk Category ◽  
Extensive Literature ◽  
Content Type ◽  
Prediction Tools ◽  
Readmission Risk

Purpose The purpose of this paper is to identify and analyse the readmission risk prediction tools reported in the literature and their benefits when it comes to healthcare organisations and management.Design/methodology/approach Readmission risk prediction is a growing topic of interest with the aim of identifying patients in particular those suffering from chronic diseases such as congestive heart failure, chronic obstructive pulmonary disease and diabetes, who are at risk of readmission. Several models have been developed with different levels of predictive ability. A structured and extensive literature search of several databases was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analysis strategy, and this yielded a total of 48,984 records.Findings Forty-three articles were selected for full-text and extensive review after following the screening process and according to the eligibility criteria. About 34 unique readmission risk prediction models were identified, in which their predictive ability ranged from poor to good (c statistic 0.5–0.86). Readmission rates ranged between 3.1 and 74.1% depending on the risk category. This review shows that readmission risk prediction is a complex process and is still relatively new as a concept and poorly understood. It confirms that readmission prediction models hold significant accuracy at identifying patients at higher risk for such an event within specific context.Research limitations/implications Since most prediction models were developed for specific populations, conditions or hospital settings, the generalisability and transferability of the predictions across wider or other contexts may be difficult to achieve. Therefore, the value of prediction models remains limited to hospital management. Future research is indicated in this regard.Originality/value This review is the first to cover readmission risk prediction tools that have been published in the literature since 2011, thereby providing an assessment of the relevance of this crucial KPI to health organisations and managers.

Force tracking control of grinding end effector based on backstepping + PID

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shijie Dai ◽  
Shining Li ◽  
Wenbin Ji ◽  
Zhenlin Sun ◽  
Yufeng Zhao
Keyword(s):  
Mathematical Model ◽  
Linear System ◽  
Control Strategy ◽  
Grinding Force ◽  
Constant Force ◽  
End Effector ◽  
Content Type ◽  
Modeling And Analysis ◽  
The Mathematical Model ◽  
Automobile Wheel

Purpose This study aims to realize the constant force grinding of automobile wheel hub. Design/methodology/approach A force control strategy of backstepping + proportion integration differentiation (PID) is proposed. The grinding end effector is installed on the flange of the robot. The robot controls the position and posture of the grinding end actuator and the grinding end actuator controls the grinding force output. First, the modeling and analysis of the grinding end effector are carried out, and then the backstepping + PID method is adopted to control the grinding end effector to track the expected grinding force. Finally, the feasibility of the proposed method is verified by simulation and experiment. Findings The simulation and experimental results show that the backstepping + PID strategy can track the expected force quickly, and improve the dynamic response performance of the system and the quality of grinding and polishing of automobile wheel hub. Research limitations/implications The mathematical model is based on the pneumatic system and ideal gas, and ignores the influence of friction in the working process of the cylinder, so the mathematical model proposed in this study has certain limitations. A new control strategy is proposed, which is not only used to control the grinding force of automobile wheels, but also promotes the development of industrial control. Social implications The automatic constant force grinding of automobile wheel hub is realized, and the manpower is liberated. Originality/value First, the modeling and analysis of the grinding end effector are carried out, and then the backstepping + PID method is adopted to control the grinding end effector to track the expected grinding force. The nonlinear model of the system is controlled by backstepping method, and in the process, the linear system composed of errors is obtained, and then the linear system is controlled by PID to realize the combination of backstepping and PID control.

Forecasting the risk at infractions: an ensemble comparison of machine learning approach

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lei Li ◽  
Desheng Wu
Keyword(s):  
Machine Learning ◽  
Prediction Models ◽  
Short Term Memory ◽  
Model Performance ◽  
Large Data ◽  
Support Vector ◽  
Learning Approaches ◽  
Content Type ◽  
Day To Day Operations ◽  
Prediction Approach

PurposeThe infraction of securities regulations (ISRs) of listed firms in their day-to-day operations and management has become one of common problems. This paper proposed several machine learning approaches to forecast the risk at infractions of listed corporates to solve financial problems that are not effective and precise in supervision.Design/methodology/approachThe overall proposed research framework designed for forecasting the infractions (ISRs) include data collection and cleaning, feature engineering, data split, prediction approach application and model performance evaluation. We select Logistic Regression, Naïve Bayes, Random Forest, Support Vector Machines, Artificial Neural Network and Long Short-Term Memory Networks (LSTMs) as ISRs prediction models.FindingsThe research results show that prediction performance of proposed models with the prior infractions provides a significant improvement of the ISRs than those without prior, especially for large sample set. The results also indicate when judging whether a company has infractions, we should pay attention to novel artificial intelligence methods, previous infractions of the company, and large data sets.Originality/valueThe findings could be utilized to address the problems of identifying listed corporates' ISRs at hand to a certain degree. Overall, results elucidate the value of the prior infraction of securities regulations (ISRs). This shows the importance of including more data sources when constructing distress models and not only focus on building increasingly more complex models on the same data. This is also beneficial to the regulatory authorities.

Enhanced prediction of vulnerable Web components using Stochastic Gradient Boosting Trees

2019 ◽  
Vol 15 (2) ◽  
pp. 201-214 ◽  
Author(s):  
Mahmoud Elish
Keyword(s):  
Web Applications ◽  
Prediction Models ◽  
Stochastic Gradient ◽  
Gradient Boosting ◽  
Data Sets ◽  
Content Type ◽  
Stochastic Gradient Boosting ◽  
Security Inspection ◽  
Novel Model ◽  
Efficient Software

Purpose Effective and efficient software security inspection is crucial as the existence of vulnerabilities represents severe risks to software users. The purpose of this paper is to empirically evaluate the potential application of Stochastic Gradient Boosting Trees (SGBT) as a novel model for enhanced prediction of vulnerable Web components compared to common, popular and recent machine learning models. Design/methodology/approach An empirical study was conducted where the SGBT and 16 other prediction models have been trained, optimized and cross validated using vulnerability data sets from multiple versions of two open-source Web applications written in PHP. The prediction performance of these models have been evaluated and compared based on accuracy, precision, recall and F-measure. Findings The results indicate that the SGBT models offer improved prediction over the other 16 models and thus are more effective and reliable in predicting vulnerable Web components. Originality/value This paper proposed a novel application of SGBT for enhanced prediction of vulnerable Web components and showed its effectiveness.

scholarly journals Mathematical modeling and harmonic analysis of SISFCL

2017 ◽  
Vol 36 (1) ◽  
pp. 258-270
Author(s):  
Debraj Sarkar ◽  
Debabrata Roy ◽  
Amalendu Bikash Choudhury ◽  
Sotoshi Yamada
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Harmonic Analysis ◽  
Voltage Drop ◽  
Element Model ◽  
Iron Core ◽  
Content Type ◽  
Hysteresis Characteristic ◽  
The Core ◽  
The Mathematical Model

Purpose A saturated iron core superconducting fault current limiter (SISFCL) has an important role to play in the present-day power system, providing effective protection against electrical faults and thus ensuring an uninterrupted supply of electricity to the consumers. Previous mathematical models developed to describe the SISFCL use a simple flux density-magnetic field intensity curve representing the ferromagnetic core. As the magnetic state of the core affects the efficient working of the device, this paper aims to present a novel approach in the mathematical modeling of the device with the inclusion of hysteresis. Design/methodology/approach The Jiles–Atherton’s hysteresis model is utilized to develop the mathematical model of the limiter. The model is numerically solved using MATLAB. To support the validity of model, finite element model (FEM) with similar specifications was simulated. Findings Response of the limiter based on the developed mathematical model is in close agreement with the FEM simulations. To illustrate the effect of the hysteresis, the responses are compared by using three different hysteresis characteristics. Harmonic analysis is performed and comparison is carried out utilizing fast Fourier transform and continuous wavelet transform. It is observed that the core with narrower hysteresis characteristic not only produces a better current suppression but also creates a higher voltage drop across the DC source. It also injects more harmonics in the system under fault condition. Originality/value Inclusion of hysteresis in the mathematical model presents a more realistic approach in the transient analysis of the device. The paper provides an essential insight into the effect of the core hysteresis characteristic on the device performance.

scholarly journals Impact of the moisture content in medium sands on CPTU test results

2016 ◽  
Vol 48 (3) ◽  
pp. 221-231 ◽  
Author(s):  
Łukasz Zawadzki ◽  
Marek Bajda
Keyword(s):  
Moisture Content ◽  
Unsaturated Soils ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Degree Of Saturation ◽  
Test Results ◽  
Time Dynamic ◽  
Tip Resistance ◽  
The Impact ◽  
Resistance Value

Abstract Soils occurring in the soil “active zone” are in contact with the surface and are directly influenced by external factors (mainly climatic changes) that cause variation in their parameters over time. Dynamic and uncontrolled changes of soil properties e.g. due to rainfall and evapotranspiration processes may affect field test results leading to the misinterpretation of the obtained data. This paper presents investigations on the influence of moisture content changes in sandy soils on CPTU results. For this purpose, a field ground model has been constructed and five CPTU tests with a different moisture content of soil were carried out. During the investigations, the tip resistance (qc), friction on sleeve (fs), and pore water pressure (u2) were measured. Moreover, a TDR probe was applied to determine the distribution of the moisture content in the studied soil columns. Differences between CPT results obtained in saturated and unsaturated soils have been shown. Furthermore, a simple equation to correct the tip resistance value due to the impact of the degree of saturation has been proposed.

Realistic design of laser powder bed fusion channels

2020 ◽  
Vol 26 (10) ◽  
pp. 1827-1836
Author(s):  
Christopher Gottlieb Klingaa ◽  
Sankhya Mohanty ◽  
Jesper Henri Hattel
Keyword(s):  
Surface Roughness ◽  
Prediction Models ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Channel Design ◽  
Conformal Cooling ◽  
Content Type ◽  
Powder Bed ◽  
Cooling Channels ◽  
Conformal Cooling Channels

Purpose Conformal cooling channels in additively manufactured molds are superior over conventional channels in terms of cooling control, part warpage and lead time. The heat transfer ability of cooling channels is determined by their geometry and surface roughness. Laser powder bed fusion manufactured channels have an inherent process-induced dross formation that may significantly alter the actual shape of nominal channels. Therefore, it is crucial to be able to predict the expected surface roughness and changes in the geometry of metal additively manufactured conformal cooling channels. The purpose of this paper is to present a new methodology for predicting the realistic design of laser powder bed fusion channels. Design/methodology/approach This study proposes a methodology for making nominal channel design more realistic by the implementation of roughness prediction models. The models are used for altering the nominal shape of a channel to its predicted shape by point cloud analysis and manipulation. Findings A straight channel is investigated as a simple case study and validated against X-ray computed tomography measurements. The modified channel geometry is reconstructed and meshed, resulting in a predicted, more realistic version of the nominal geometry. The methodology is successfully tested on a torus shape and a simple conformal cooling channel design. Finally, the methodology is validated through a cooling test experiment and comparison with simulations. Practical implications Accurate prediction of channel surface roughness and geometry would lead toward more accurate modeling of cooling performance. Originality/value A robust start to finish method for realistic geometrical prediction of metal additive manufacturing cooling channels has yet to be proposed. The current study seeks to fill the gap.

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