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Discrete simulation and micromechanical analysis of two-dimensional saturated granular media

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Particuology 2014年第4期12卷 138-150页

作者： younes Khalili Ahmad Mahboubi Department of Civil and Environmental Engineering.Power and Water University of Technology TehranIran

In this study, a novel approach to incorporate the pore water pressure in the discrete element method （DEM） to comprehensively model saturated granular media was developed. A numerical model was constructed based on the DEM by implanting additional routines in the basic DEM code; pore water pressure calculations were used with a two-dimensional （2D） model to simulate the undrained behavior of satu- rated granular media. This model coupled the interaction of solid particles and the pore fluid in saturated granular media. Finally, several 2D undrained shear tests were simulated. The test results showed that the model could predict the response of the saturated granular soil to shear loading. The effect of initial compaction was investigated. Biaxial tests on dense and loose specimens were conducted, and the effect of the initial density on the change in shear strength and the volume change of the system was inves- tigated. The overall behavior of loose and dense specimens was phenomenologically similar to the real granular material. Constant volume tests were simulated, and the results were compared to those from the coupled model. Induced anisotropy was micromechanically investigated by studying the contact force orientation. The change in anisotropy depended on the modeling scheme. However, the overall responses of the media obtained usinz the couoled and constant volume methods were similar.

关键词： DEM Saturated granular media Numerical simulation Micromechanical investigation

Non-Monotonic Lyapunov-Krasovskii Functional Approach to Stability Analysis and Stabilization of Discrete Time-Delay Systems

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IEEE/CAA Journal of Automatica Sinica 2020年第3期7卷 752-763页

作者： younes Solgi Alireza Fatehi Ala Shariati Advanced Process Automation and Control Research Group Industrial Control Center of ExcellenceFaculty of Electrical EngineeringK.N.Toosi University of TechnologyTehran 16317-14191Iran IEEE

In this paper, a novel non-monotonic Lyapunov-Krasovskii functional approach is proposed to deal with the stability analysis and stabilization problem of linear discrete time-delay systems. This technique is utilized to relax the monotonic requirement of the Lyapunov-Krasovskii theorem. In this regard, the Lyapunov-Krasovskii functional is allowed to increase in a few steps, while being forced to be overall decreasing. As a result, it relays on a larger class of Lyapunov-Krasovskii functionals to provide stability of a state-delay system. To this end, using the non-monotonic Lyapunov-Krasovskii theorem, new sufficient conditions are derived regarding linear matrix inequalities(LMIs)to study the global asymptotic stability of state-delay ***, new stabilization conditions are also proposed for time-delay systems in this article. Both simulation and experimental results on a p H neutralizing process are provided to demonstrate the efficacy of the proposed method.

关键词： Linear matrix inequality(LMI) non-monotonic Lyapunov-Krasovskii functional(NMLKF) pH neutralization plant stabilization state-delay system time-delay system

Novel Non-monotonic Lyapunov-Krasovskii Based Stability Analysis and Stabilization of Discrete State-delay System

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International Journal of Automation and computing 2020年第5期17卷 713-732页

作者： younes Solgi Alireza Fatehi Ala Shariati APAC Research Group Industrial Control Center of ExcellenceFaculty of Electrical EngineeringK.N.Toosi University of TechnologyTehran ***Iran

This paper proposes a novel less-conservative non-monotonic Lyapunov-Krasovskii stability approach for stability analysis of discrete time-delay *** this method,monotonically decreasing requirements of the Lyapunov-Krasovskii method are replaced with non-monotonic *** Lyapunov-Krasovskii functional is allowed to increase in some steps,but the overall trend should be *** model of practical systems used for stability analysis usually contain ***,firstly a non-monotonic stability condition is derived for certain discrete time-delay systems,then robust non-monotonic stability conditions are proposed for uncertain ***,a novel stabilization algorithm is derived based on the introduced non-monotonic stability *** Lyapunov-Krasovskii functional and the controller are obtained by solving a set of linear matrix inequalities(LMI)or iterative LMI based nonlinear *** proposed theorems are first evaluated by some numerical examples,and then by simulation and implementation on the pH neutralizing process plant.

关键词： Lyapunov-Krasovskii functional discrete state-delay systems non-monotonic Lyapunov function robust stability stabilization

A new technique for solving the multi-objective optimization problem using hybrid approach

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Frontiers in Energy 2014年第4期8卷 490-503页

作者： Mimoun younes Khodja FOUAD Belabbes BAGDAD Faculty of Technology Djillali Liabes University Sidi Bel Abbes 22000 Alegria

Energy efficiency, which consists of using less energy or improving the level of service to energy consumers, refers to an effective way to provide overall energy. But its increasing pressure on the energy sector to control greenhouse gases and to reduce CO2 emissions forced the power system operators to consider the emission problem as a consequential matter besides the economic problems. The economic power dispatch problem has, therefore, become a multi-objective optimization problem. Fuel cost, pollutant emissions, and system loss should be minimized simultaneously while satisfying certain system constraints. To achieve a good design with different solutions in a multi-objective optimization problem, fuel cost and pollutant emissions are converted into single optimization problem by introducing penalty factor. Now the power dispatch is formulated into a hi-objective optimization problem, two objectives with two algorithms, firefly algorithm for optimization the fuel cost, pollutant emissions and the real genetic algorithm for minimization of the transmission losses. In this paper the new approach （firefly algorithm-real genetic algorithm, FFA-RGA） has been applied to the standard IEEE 30-bus 6-generator. The effectiveness of the proposed approach is demonstrated by comparing its performance with other evolutionary multi- objective optimization algorithms. Simulation results show the validity and feasibility of the proposed method.

关键词： economic power dispatch (EPD) firefly algo- rithm (FFA) real genetic algorithm (RGA) hybrid method

Unconfined compressive strength prediction of soils stabilized using artificial neural networks and support vector machines

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Frontiers of Structural and Civil Engineering 2021年第2期15卷 520-536页

作者： Alireza TABARSA Nima LATIFI Abdolreza OSOULI younes BAGHERI Depatrment of Civil Engineering Faculty of EngineeringGolestan UniversityGorgan 49138-15759Iran Terr aeon Consultants Inc.NashvilleTN 37211USA Civil Engineering Department Southern Illinois UniversityEdwardsvilleIL 62026-1800USA Faculty of Engineering Mirdamad Institute of Higher EducationGorgan 49166-53989Iran

This study aims to improve the unconfined compressive strength of soils using additives as well as by predicting the strength behavior of stabilized soils using two artificial-intelligence-based *** soils used in this study are stabilized using various combinations of cement,lime,and rice husk *** predict the results of unconfined compressive strength tests conducted on soils,a comprehensive laboratory dataset comprising 137 soil specimens treated with different combinations of cement,lime,and rice husk ash is *** artificial-intelligence-based models including artificial neural networks and support vector machines are used comparatively to predict the strength characteristics of soils treated with cement,lime,and rice husk ash under different *** suggested models predicted the unconfined compressive strength of soils accurately and can be introduced as reliable predictive models in geotechnical *** study demonstrates the better performance of support vector machines in predicting the strength of the investigated soils compared with artificial neural *** type of kernel function used in support vector machine models contributed positively to the performance of the proposed ***,based on sensitivity analysis results,it is discovered that cement and lime contents impose more prominent effects on the unconfined compressive strength values of the investigated soils compared with the other parameters.

关键词： unconfined compressive strength artificial neural network support vector machine predictive models regression

Effects of wollastonite nanofibers on fluid flow in medium-density fiberboard

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Journal of Forestry Research 2016年第1期27卷 209-217页

作者： hamid R.Taghiyari younes Sarvari Samadi Wood Science and Technology Department Faculty of Civil Engineering Shahid Rajaee Teacher Training University Faculty of Wood Technology and Construction Rosenheim University of Applied Sciences

We studied the effect of wollastonite nanofibers on fluid flow in medium-density fiberboard （MDF）. Nanowollastonite （NW） was applied in MDF at 10 %, based on the dry weight of wood fibers. We also tested chicken feathers as an additive to the matrix at 5 and 10 % by weight. The weight of feathers was reduced from the wood fibers to keep the density of the panels constant （0.66 g cm-3）. Wollastonite nanofibers acted as filler in the matrix and significantly decreased gas and liquid perme- ability. Higher thermal conductivity of the N-W-treated MDF-mats resulted in a better cure of resin, and conse- quently more integrity in the composite-matrix and lower permeability. The water-repellant property of wollastonite also contributed to the decrease in liquid permeability. Feathers reduced gas and liquid permeability due to the hydrophobic nature of keratin, as well as its formation as a physical barrier towards passing of fluids. Ten percent feather content proved too high and some checks and cracks occurred in the core of the panels after hot-pressing. Panels with 5 %-feather content resulted in both lower fluid flow and adequate physical integrity in the core sec- tion of the MDF-matrix.

关键词： Chicken feather Composite board Mineralmaterials Thermal conductivity coefficient Wollastonitenanofibers Wood fiber

Metasurfaces for next-generation wireless communication systems

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National Science Review 2023年第8期10卷 17-19页

作者： younes Ra'di Nikita Nefedkin Petar Popovski Andrea Alù Department of Electrical Engineering and Computer Science Syracuse University Photonics Initiative Advanced Science Research Center City University of New York Department of Electronic Systems Aalborg University Physics Program Graduate Center City University of New York

The pace of development in the world of 5G communication systems has proven to be much more demanding than previous generations, with 5G-Advanced seemingly around the corner [1]. Extensive research is already underway to structure the next generation of wireless systems(i.e. 6G), which may potentially enable an unprecedented level of human–machine interaction [2].

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A systematic review of occupational exposure to respirable coal mine dust(RCMD)in the *** industry

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International Journal of Coal Science & Technology 2023年第2期10卷 32-44页

作者： younes Shekarian Elham Rahimi Mohammad Rezaee Pedram Roghanchi John and Willie Leone Family Department of Energy and Mineral Engineering Earth and Mineral Sciences(EMS)Energy InstituteThe Pennsylvania State UniversityUniversity ParkUSA Department of Mineral Engineering New Mexico Institute of Mining and TechnologySocorroNMUSA

Cumulative inhalation of respirable coal mine dust(RCMD)can lead to severe lung diseases,including coal worker's pneu-moconiosis(CWP),silicosis,mixed dust pneumoconiosis,dust-related diffuse fibrosis(DDF),and progressive massive fibrosis(PMF).Statistics from the number of reported cases showed a significant decrease in the progression of respiratory diseases in the ***,an unexpected increase in the number of CWP cases was reported in the late *** date,there has been no comprehensive systematic review to assess all contributing factors to the resurgence of CWP *** study aims to investigate the effects of various mining parameters on the prevalence of CWP in coal mines.A systematic review using the preferred reporting items for systematic reviews and meta-analysis(PRISMA)method was conducted to investigate the health effects of RCMD exposure and identify the factors that may contribute to the recent resurgence of CWP *** systematic review yielded a total of 401 papers,which were added to the *** total number of 148 and 208 papers were excluded from the database in the process of screening and eligibility,***,18 papers were considered for data selection and full-text *** review revealed that factors including geographic location,mine size,mining operation type,coal-seam thickness,coal rank,changes in mining practices,technology advancement,and engi-neering dust control practices are contributing to the recent resurgence of CWP among coal ***,the evidence for root causes is limited owing to the methodological constraints of the studies;therefore,further detailed studies are needed.

关键词： Respirable coal mine dust Systematic review Coal worker's pneumoconiosis Respiratory diseases Exposure limit Occupational exposure

Tocotrienol isoforms:The molecular mechanisms underlying their effects in cancer therapy and their implementation in clinical trials

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Journal of Integrative Medicine 2024年第1期22卷 1-11页

作者： Maria younes Ghady Loubnane Christopher Sleiman Sandra Rizk Department of Natural Sciences Lebanese American UniversityByblosLebanon

Tocotrienols are found in a variety of natural sources,like rice bran,annatto seeds and palm oil,and have been shown to have several health-promoting properties,particularly against chronic diseases such as *** incidence of cancer is rapidly increasing around the world,not only a result of continued aging and population growth,but also due to the adoption of aspects of the Western lifestyle,such as high-fat diets and low-physical *** literature provides strong evidence that tocotrienols are able to inhibit the growth of various cancers,including breast,lung,ovarian,prostate,liver,brain,colon,myeloma and pancreatic *** findings,along with the reported safety profile of tocotrienols in healthy human volunteers,encourage further research into these compounds’potential use in cancer prevention and *** current review provided detailed information about the molecular mechanisms of action of different tocotrienol isoforms in various cancer models and evaluated the potential therapeutic effects of different vitamin E analogues on important cancer hallmarks,such as cellular proliferation,apoptosis,angiogenesis and ***/PubMed and Scopus databases were used to identify recently published articles that investigated the anticancer effects of vitamin E derivatives in various types of cancer in vitro and in vivo along with clinical evidence of adjuvant chemopreventive *** an overview of pre-clinical studies,we describe several completed and ongoing clinical trials that are paving the way for the successful implementation of tocotrienols in cancer chemotherapy.

关键词： Vitamin E Tocotrienols Cancer Molecular mechanism Clinical trials