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Machine-learning-based head impact subtyping based on the spectral densities of the measurable head kinematics

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Journal of Sport and Health Science 2023年第5期12卷 619-629,F0003页

作者： Xianghao Zhan Yiheng Li Yuzhe Liu Nicholas J.Cecchi Samuel J.Raymond Zhou Zhou Hossein vahid alizadeh Jesse Ruan Saeed Barbat Stephen Tiernan Olivier Gevaert Michael M.Zeineh Gerald A.Grant David B.Camarillo Department of Bioengineering Stanford UniversityStanfordCA 94305USA Department of Biomedical Data Science Stanford UniversityStanfordCA 94305USA Ford Motor Company 3001 Miller RdDearbornMI 48120USA Technological University Dublin DublinD07 EWV4Ireland Department of Radiology Stanford UniversityStanfordCA 94305USA Department of Neurosurgery Stanford UniversityStanfordCA 94305USA

Background:Traumatic brain injury can be caused by head impacts,but many brain injury risk estimation models are not equally accurate across the variety of impacts that patients may undergo,and the characteristics of different types of impacts are not well *** investigated the spectral characteristics of different head impact types with kinematics ***:Data were analyzed from 3262 head impacts from lab reconstruction,American football,mixed martial arts,and publicly available car crash data.A random forest classifier with spectral densities of linear acceleration and angular velocity was built to classify head impact types(e.g.,football,car crash,mixed martial arts).To test the classifier robustness,another 271 lab-reconstructed impacts were obtained from 5 other instrumented ***,with the classifier,type-specific,nearest-neighbor regression models were built for brain ***:The classifier reached a median accuracy of 96% over 1000 random partitions of training and test *** most important features in the classification included both low-and high-frequency features,both linear acceleration features and angular velocity *** head impact types had different distributions of spectral densities in low-and high-frequency ranges(e.g.,the spectral densities of mixed martial arts impacts were higher in the high-frequency range than in the low-frequency range).The type-specific regression showed a generally higher R2value than baseline models without ***:The machine-learning-based classifier enables a better understanding of the impact kinematics spectral density in different sports,and it can be applied to evaluate the quality of impact-simulation systems and on-field data augmentation.

关键词： Classification Contact sports Head impacts Impact kinematics Traumatic brain injuryTagedAPTARAEnd

Structural and Mechanical Properties of Al/B_4C Composites Fabricated by Wet Attrition Milling and Hot Extrusion

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Journal of Materials Science & Technology 2013年第8期29卷 725-730页

作者： Morteza alizadeh Mostafa alizadeh Rasool Amini Department of Materials Science and Engineering Shiraz University of TechnologyModarres Blvd.71555-313 ShirazIran Department of Metals Institute of Materials Science and EngineeringGraduate University of Advanced TechnologyP.O.Box 76315-115KermanIran

In this study, Al matrix composites reinforced by 7.5 and 15 vol.% B4C particles and also monolithic Al （Al without the B4C particles） were produced by wet attrition milling and subsequent hot forward extrusion processes. The microstructure of the composites, evaluated by scanning electron microscopy （SEM）, showed that the B4C particles were properly distributed in the Al matrix. Mechanical properties of the Al/B4C composites and monolithic Al were investigated by tensile, wear and hardness tests, The results revealed that with increasing content of B4C particles, the tensile strength and microhardness of composites increased but the elongation decreased. In addition, the tensile strength and microhardness of composite samples were higher than those of monolithic Al. The density measurements revealed that the density of composites decreased with increasing content of the B4C particles.

关键词： Composites Mechanical properties Attrition milling Hot extrusion

AN IMPRINTED POLYMER FOR REMOVAL OF Cd^(2+) FROM WATER SAMPLES:OPTIMIZATION OF ADSORPTION AND RECOVERY STEPS BY EXPERIMENTAL DESIGN

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Chinese Journal of Polymer Science 2011年第6期29卷 658-669页

作者： Taher alizadeh Department of Applied Chemistry Faculty of ScienceUniversity of Mohaghegh ArdabiliArdabilIran

A new ion-imprinted polymer （liP） was synthesized by copolymerization of 4-vinylpyridine （monomer）, ethyleneglycoldimethacrylate （cross-linker） and 2,2-azobis-isobutyronitrile （initiator） in the presence of Cd2＋ and quinaldic acid （complexing agent）. It was found that the adsorption capacity of IIP and blank polymer were 45.0 and 6.2 mg g-l, respectively. The relative selectivity coefficients of the imprinted polymer for different binary mixture were also calculated. Compared to non-imprinted polymer （NIP）, the IIP had higher selectivity for Cd（II）. The IIP was used as a sorbent for cadmium extraction from water samples by using a simple batch extraction procedure. The effect of different parameters on Cd2＋ extraction and its recovery from the IIP were evaluated and optimized by using experimental design methodology. The optimized adsorption/desorption procedure was applied for cadmium removal from the real water samples. The obtained recoveries proved that this IIP could be used for removal of trace cadmium ions from water samples.

关键词： Cd2+ removal Ion imprinted polymer Solid phase extraction Experimental design

Numerical prediction of hydrodynamic cavitating flow structures and their corresponding erosion

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Journal of Hydrodynamics 2021年第3期33卷 546-571页

作者： Amirhossein Mohammadkhani Mansour alizadeh Department of Mechanical Engineering Iran University of Science and TechnologyTehranIran

Hydrodynamic cavitating flows usually consist of 3-D intense vortical flows that are detached from solid *** vortical flows normally generate heaps of cavitating flow structures,which,in turn,govern the location of cavitation erosion before ***,this study introduces a new numerical approach based on the improved delayed detached eddy simulation(IDDES)turbulence modeling for predicting cavitating ***,the solution of compressible Eulerian-Eulerian two-phase flow and the IDDES turbulence model was linked to the microjet hypothesis and unsteady behavior of pressure and vapor volume to predict the corresponding erosion of cavitating *** method for cavitation erosion prediction,a modified version taken from previous studies,was applied as a post-processing *** validation of cavitating flow predictions was performed for the first time on the Grenoble axisymmetric nozzle by comparing them with 21 photos of cavitation from the previous experimental *** results showed that the present numerical approach estimated various features of hydrodynamic cavitation well,including shedding processes and the length,shape,and collapse of cavitating *** the numerical analysis,three main stages were detected for the present cavitating flow,and the vorticity-cavitation interactions were investigated by the vorticity transport *** streak-like and tube-like cavitating(STLIC and TULIC)structures were introduced in the second stage,initiated by flow instability,and entirely governed by corresponding turbulent flow *** collapse of these cavitating structures is one of the primary sources of cavitation erosion on lower and upper *** results of the numerical erosion predictions were compared with those of the previous erosion tests on the Grenoble axisymmetric *** numerical performance was achieved in predicting the location and intensity of cavitation erosion.

关键词： Turbulent and cavitating structures cavitation erosion detached vortical flow Hybrid RANS-LES turbulence modeling flow instability flow visualization

Experimental and modeling study of the kinetics of methane hydrate formation and dissociation

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Chinese Journal of Chemical Engineering 2021年第1期34卷 365-374页

作者： Vafa Feyzi vahid Mohebbi Ahvaz Petroleum Faculty Petroleum University of Technology(PUT)AhvazIran

In this work,several experiments were conducted at isobaric and isothermal condition in a CSTR reactor to study the kinetics of methane hydrate formation and *** were performed at five temperatures and three pressure levels(corresponding to equilibrium pressure).Methane hydrate formation and dissociation rates were modeled using mass transfer limited kinetic models and mass transfer coefficients for both formation and dissociation were *** of results,shows that mass transfer coefficients for methane hydrate dissociation are one order greater than formation *** transfer coefficients were correlated by polynomials as relations of pressure and *** results and the method can be applied for prediction of methane production from naturally occurring methane hydrate deposits.

关键词： Methane hydrate Kinetics Formation Dissociation Mass transfer

Dynamic analysis of the composite laminated repaired perforated plates by using multi-patch IGA method

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Chinese Journal of Aeronautics 2021年第1期34卷 266-280页

作者： Jamshid FAZILATI vahid KHALAFI Aeronautical Science and Technology Department Aerospace Research InstituteTehran 14657-74111Iran Aerospace Engineering Department Shahid Sattari Aeronautical University of Science and TechnologyTehranIran

The bonded repair techniques seem to be the most frequent procedures in the aviation *** achieved composite repaired perforated thin-walled plate is a complex geometry with high numerical analysis *** NURBS-based Isogeometric Analysis(IGA)proposes a sensible and affordable tool to carry out such geometry *** this context,a well-known technique is to divide the original geometry assembly into number of simple neighbors connected *** the present study the free vibration analysis of the perforated plates repaired on one side with an external bonded composite laminated patch is investigated.A multi-patch geometry modeling approach is implemented in line with the first order shear deformation theory of *** order to hold the geometry integrity and uniformity,all the degrees of freedom between adjacent geometry patches are completely tied through implementing a Nitsche *** show the effectiveness and accuracy of the developed formulation,some representative results are extracted and compared with those from *** effects of geometrical as well as material parameters including boundary condition,cutout shape,and repair layup on the dynamic response of the repaired perforated plates are then investigated.

关键词： Composite laminate Perforated plate Bonded repair Isogeometric analysis(IGA) Multi-patch model

Ocean Chemistry Revealed by Mineralogical and Geochemical Evidence at the Permian——Triassic Mass Extinction,Offshore the Persian Gulf,Iran

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Acta Geologica Sinica(English Edition) 2016年第5期90卷 1852-1864页

作者： vahid TAVAKOLI School of Geology College of ScienceUniversity of Tehran

The Upper Permian Dalan Formation and the Lower Triassic Kangan Formation in the Persian Gulf area are mainly composed of shallow marine facies limestone and *** subsurface-cored intervals were investigated in order to understand the original mineralogy and paleoceanic *** decreasing trend of Sr concentration in these deposits shows that aragonite was precipitated during the Late Permian and then gradually changed to calcite toward the Permian-Triassic boundary（PTB）.The dissolution rate of aragonite decreased from 60 m below the PTB toward the boundary,with the only exception at 10 m below the Permian-Triassic Boundary（PTB） due to the Permian-Triassic unconformity in this *** increasing trend of Mg/Ca ratio in a global scale at the end-Permian time shows that the interpreted variation of mineralogy does not result from the change of this *** increasing p（CO2） and decreasing pH are considered to be the main controlling *** increase of Ca2＋ at the end-Permian time due to the input of meteoric waters is too little to fully compensate this effect.A local maximum of the Si content just at the PTB confirms the input of runoff waters.

关键词： Permian Triassic carbonate mineralogy elemental composition Iran Persian Gulf

Wedge-Shaped Pop-Up Structure in the Eslami Peninsula, Lake Urmia, Northwestern Iran

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Acta Geologica Sinica(English Edition) 2017年第4期91卷 1264-1269页

作者： Akram alizadeh Fayezeh JANGJOO Department of Geology Faculty of Science Urmia University Urmia 57153-165 Iran

Ancient subduction zones are characterized by metamorphic and orogenic belts. The Zagros Orogenic Belt comprises almost all sections of an ancient subduction zone along which Neo-Tethyan oceanic crust was subducted beneath central Iran. The Eslami Peninsula, as a part of the Zagros Orogenic Belt in Azerbaijan province, northwestern Iran, is situated between the Lake Urmia fore-arc basin and the Sahand Magmatic Arc. This region contains Eocene leucite dikes, trachyte, tephrite, phenolite, basanite and syenite. Volcanic features related to the Sahand are located in the eastern part of the Eslami Peninsula. In view of its relative age and composition, the Eslami Peninsula proposed as an outer arc of the Sahand Magmatic Arc that formed within the post-collisional setting of the central Iranian and Arabian plates. After subduction and contact of the two plates, a symmetric pop-up structure has been created by thrusting in the Zagros belt as a result of the collision processes. The injesction of dikes in the Eslami Peninsula is also a result of the continent continent collision.

关键词： Eslami Peninsula Lake Urmia Sahand post-collision Zagros

A multiscale spatio-temporal framework to regionalize annual precipitation using k-means and self-organizing map technique

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Journal of Mountain Science 2018年第7期15卷 1481-1497页

作者： Kiyoumars ROUSHANGAR Farhad alizadeh Department of Water Resources Engineering Faculty of Civil EngineeringUniversity of Tabriz

Determination of homogenous precipitation-based regions is a very important task in effective management of water resources. The present study tried to propose an effective precipitation-based regionalization methodology by conjugating both temporal pre-processing and spatial clustering approaches in a way to take advantage of multiscale properties of precipitation time series. Annual precipitation data of 51 years(1960-2010) for 31 rain gauges(RGs) were collected and used in proposed clustering approaches. Discreet wavelet transform(DWT) was used to capture the time-frequency attributes of the time series and multiscale regionalization was performed by using k-means and Self Organizing Maps(SOM) clustering techniques. Daubechies function(db) was selected as mother wavelet to decompose the precipitation time series. Also, proper boundary extensions and decomposition level were applied. Different combinations of the approximation(A) and detail(D) coefficients were used to determine the input dataset as a basis of spatial clustering. The proposed model's efficiency in spatial clustering stage was verified using three different indexes namely, Silhouette Coefficient(SC), Dunn index and Davis Bouldin index(DB). Results approved superior performance of k-means technique in comparison to SOM. It was also deduced that DWT-based regionalization methodology showed improvements in comparison to historical-based models. Cross mutual information was used to investigate the RGs of cluster 3's homogeneousness in DWT-k-means approach. Results of non-linear correlation approach verified homogeneity of cluster 3. Verifications based on mean annual precipitation values of rain gauges in each cluster also approved the capability of multiscale approach in precipitation regionalization.

关键词： Precipitation Discrete wavelet transform (DWT) k-means Self Organizing Map(SOM) Iran