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Theory of Flexural Shear, Bending and Torsion for a Thin-Walled Beam of Open Section

World Journal of mechanics 2024年第3期14卷 23-53页

作者： david W. A. Rees Abdelraouf m. Sami Alsheikh College of Engineering and Design Brunel University Uxbridge UK

Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at which transverse shear forces when applied do not produce torsion. This centre, when taken to be coincident with the centre of twist implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric with the shear centre will twist but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers with a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-walled sections when the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular twist and the free warping displacement. It is shown from the Wagner-Kappus torsion theory how the end constrained warping generates an axial stress distribution that varies with the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for wider applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the web centre. Therein, both bending and twisting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified with the sum of axial stress

关键词： Thin Wall Theory Cantilever Beam Open Channel Section Principal Axes Flexure Transverse Shear Torsion Shear Centre Shear Flow Warping Fixed-End Constraint

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Cognitive function among military veterans with STEm occupations

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military medical Research 2024年第2期11卷 308-310页

作者： Justin T.mcDaniel Kevin N.Hascup Erin R.Hascup Ugochukwu G.Ezigbo Amanda m.Weidhuner Harvey Henson david L.Albright Dale and Deborah Smith Center for Alzheimer's Research and trEatment(CARE) Southern Illinois University School of MedicineSpringfieldIL 62794USA STEm Education Research Center Southern Illinois UniversityCarbondaleIL 62901USA Department of Political Science The University of AlabamaTuscaloosaAL 35487USA

Dear Editor,There is limited research on the relationship between science,technology,engineering,and mathematics(STEm)occupational history and cognitive function in later life,especially among military veterans,who may be at greater risk for later-life cognitive *** study examines a nationally representative sample of military veterans to address this gap in knowledge.

关键词： Alzheimer's disease Veterans Science technology engineering and mathematics(STEm) Animal fluency test Dementia

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AutomL: A systematic review on automated machine learning with neural architecture search

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Journal of Information and Intelligence 2024年第1期2卷 52-81页

作者： Imrus Salehin md.Shamiul Islam Pritom Saha S.m.Noman Azra Tuni md.mehedi hasan md.Abu Baten Department of Computer Engineering Dongseo University47 Jurye-roSasang-guBusan 47011Republic of Korea Department of Computer Science and Engineering Daffodil International UniversityDhaka 1216Bangladesh Department of Computer Science and Engineering Bangladesh University of Business and TechnologyDhaka 1216Bangladesh Faculty of Computer Science and Engineering Frankfurt University of Applied SciencesFrankfurt 60318Germany Department of Computer Science and Engineering University of Asia PacificDhaka 1205Bangladesh Department of Computer Science and Engineering Ahsanullah University of Science and TechnologyDhaka 1208Bangladesh Department of Computer Science and Engineering Northern University BangladeshDhaka 1215Bangladesh

AutomL(Automated machine Learning)is an emerging field that aims to automate the process of building machine learning *** emerged to increase productivity and efficiency by automating as much as possible the inefficient work that occurs while repeating this process whenever machine learning is *** particular,research has been conducted for a long time on technologies that can effectively develop high-quality models by minimizing the intervention of model developers in the process from data preprocessing to algorithm selection and *** this semantic review research,we summarize the data processing requirements for AutomL approaches and provide a detailed *** place greater emphasis on neural architecture search(NAS)as it currently represents a highly popular sub-topic within the field of *** methods use machine learning algorithms to search through a large space of possible architectures and find the one that performs best on a given *** provide a summary of the performance achieved by representative NAS algorithms on the CIFAR-10,CIFAR-100,ImageNet and wellknown benchmark ***,we delve into several noteworthy research directions in NAS methods including one/two-stage NAS,one-shot NAS and joint hyperparameter with architecture *** discussed how the search space size and complexity in NAS can vary depending on the specific problem being *** conclude,we examine several open problems(SOTA problems)within current AutomL methods that assure further investigation in future research.

关键词： AutomL Neural architecture search Advance machine learning Search space Hyperparameter optimization

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Efficiency improvement by using metal–insulator‑semiconductor structure in InGaN/GaN micro‑light‑emitting diodes

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Frontiers of Optoelectronics 2024年第1期17卷 77-84页

作者： Jian Yin david Hwang Hossein Zamani Siboni Ehsanollah Fathi Reza Chaji Dayan Ban Department of Electrical and Computer Engineering Waterloo Institute NanotechnologyUniversity of WaterlooWaterlooON N2L 3G1Canada Vuereal InC. 440 Philip StreetUnit 100WaterlooON N2L 5R9Canada

InGaN/GaN micro-light-emitting diodes(micro-LEDs)with a metal–insulator-semiconductor(mIS)structure on the sidewall are proposed to improve *** this mIS structure,a sidewall electrode is deposited on the insulating layer-coated sidewall of the device mesa between a cathode on the bottom and an anode on the ***(EL)measurements of fabricated devices with a mesa diameter of 10μm show that the application of negative biases on the sidewall electrode can increase the device external quantum efficiency(EQE).In contrast,the application of positive biases can decrease the *** band structure analysis reveals that the EQE is impacted because the application of sidewall electric fields manipulates the local surface electron density along the mesa sidewall and thus controls surface Shockley–Read–Hall(SRH)*** suggested strategies,reducing insulator layer thickness and exploring alternative materials,can be implemented to further improve the EQE of mIS micro-LEDs in future fabrication.

关键词： micro-LED GaN EQE improvement micro-fabrication

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Finding the magnetopause location using soft X-ray observations and a statistical inverse method

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Earth and Planetary Physics 2024年第1期8卷 184-203页

作者： Gonzalo Cucho-Padin Hyunju Connor Jaewoong Jung Brian Walsh david G.Sibeck Space Weather Laboratory NASA Goddard Space Flight CenterGreenbeltMDUSA Department of Physics The Catholic University of AmericaWashingtonDCUSA Geospace Physics Laboratory NASA Goddard Space Flight CenterGreenbeltMDUSA Astronomy Department University of Maryland College ParkCollege ParkMDUSA Center for Space Physics Department of Mechanical EngineeringBoston UniversityBostonMAUSA

Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the *** spatial and temporal properties of the magnetopause,under varying solar and magnetospheric conditions,remain largely unknown because empirical studies using in-situ observations are challenging to *** wide field-of-view(FOV)imaging is the only means to simultaneously observe the spatial distribution of the plasma properties over the vast dayside magnetospheric region and,subsequently,quantify the energy transport from the interplanetary medium into the terrestrial *** upcoming missions,ESA/CAS SmILE and NASA’s LEXI will provide wide-field imagery of the dayside magnetosheath in soft X-rays,an emission generated by charge exchange interactions between high charge-state heavy ions of solar wind origin and exospheric neutral ***-cadence two-dimensional observations of the magnetosheath will allow the estimation of dynamic properties of its inner boundary,the magnetopause,and enable studies of its response to changes in the solar wind dynamic pressure and interplanetary magnetic field *** work introduces a statistically-based estimation approach based on inverse theory to estimate the spatial distribution of magnetosheath soft X-ray emissivities and,with this,identify the location of the magnetopause over the Sun−Earth *** do so,we simulate the magnetosheath structure using the mHD-based OpenGGCm model and generate synthetic soft X-ray images using LEXI’s orbit and attitude *** results show that 3-D estimations using the described statistically-based technique are robust against Poisson-distributed shot noise inherent to soft X-ray ***,our proposed methodology shows that the accuracy of both three-dimensional(3-D)estimation and the magnetopause standoff distance calculation hi

关键词： magnetopause soft X-ray tomography

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An Investigation into Forced Convection of a Nanofluid Flowing in a Rectangular microchannel under the Influence of a magnetic Field

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Fluid Dynamics & materials Processing 2024年第2期20卷 311-323页

作者： muataz S.Alhassan Ameer A.Alameri Andrés Alexis Ramírez-Coronel I.B.Sapaev Azher m.Abed david-Juan Ramos-Huallpartupa Rahman S.Zabibah Division of Advanced Nanomaterial Technologies Scientific Research CenterAl-Ayen UniversityThi-QarIraq Department of Chemistry College of ScienceUniversity of BabylonBabylonIraq Research Group in Educational Statistics National University of EducatiosnAzoguesEcuador Department Physics and Chemistry Tashkent Institute of Irrigation and Agricultural Mechanization EngineersNational Research UniversityTashkentUzbekistan Akfa University TashkentUzbekistan New Uzbekistan University TashkentUzbekistan Department of Airconditioning and Refrigeration Engineering Al-Mustaqbal University CollegeHilla51001Iraq Academic Department of Agro-Industrial Engineering and Technology Universidad Nacional JoséMaría ArguedasApurimacPerú The Islamic University NajafIraq

In line with recent studies,where it has been shown that nanoﬂuids containing graphene have a stronger capacity to boost the heat transfer coefﬁcient with respect to ordinary nanoﬂuids,experiments have been conducted using water with cobalt ferrite/graphene *** particular,a circular channel made of copper subjected to a constant heatﬂux has been *** nanoparticles are sensitive to the presence of a magneticﬁeld,different conditions have been examined,allowing both the strength and the frequency of such aﬁeld to span relatively wide ranges and assuming different concentrations of *** to theﬁndings,the addition of nanoparticles to theﬂuid causes its rotation speed to increase by a factor of two,whereas ultraviolet radiation plays a negligible *** amount of time required to attain the maximum rotation speed of the nanoﬂuid and the Nusselt number have been measured under both constant and alternating magneticﬁelds for a ferroﬂuid with a concentration of 0.5%and atﬂow Reynolds number of 550 and 1750.

关键词： Nano fluid rectengular tube magnetic field

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Acceptor doping and actuation mechanisms in Sr-doped BiFeO_(3)-BaTiO_(3)ceramics

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Journal of materiomics 2024年第1期10卷 57-69页

作者： Ziqi Yang Yizhe Li Bing Wang Juncheng Pan Annette K.Kleppe david A.Hall Department of materials University of ManchesterM139PLManchesterUK Diamond Light Source Ltd. Harwell Science and Innovation CampusOX110DEDidcotUK

BiFeO_(3)-BaTiO_(3)(BF-BT)ceramics are important multiferroic materials,which are attracting significant attention for potential applications in high temperature lead-free piezoelectric *** the present study,the effects of Sr^(2+)as an acceptor dopant for Bi^(3+),in the range from 0 to 1.0%(in mole),on the structure and ferroelectric/piezoelectric properties of 0.7BiFeO_(3)-0.3BaTiO_(3)ceramics were *** use of a post-sintering Ar annealing process was found to be an effective approach to reduce electrical conductivity induced by the presence of electron holes associated with reoxidation during cooling.A low Sr dopant concentration(0.3%,in mole)yielded enhanced ferroelectric(P_(max)∼0.37 C/m^(2),P_(r)∼0.30 C/m^(2))and piezoelectric(d_(33)∼178 pC/N,k_(p)∼0.27)properties,whereas higher levels led to chemically heterogeneous core-shell structures and secondary phases with an associated decline in *** electric field-induced strain of the Sr-doped BF-BT ceramics was investigated using a combination of digital image correlation macroscopic strain measurements and in-situ synchrotron X-ray *** of the intrinsic(lattice strain)and extrinsic(domain switching)contributions to the electric field induced strain indicated that the intrinsic contribution dominated during the poling process.

关键词： Bismuth ferrite-barium titanate Acceptor doping Electroceramics Piezoelectricity In-situ X-ray diffraction

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Epidemiology and control of monkeypox outbreak in Houston,Texas

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Global Health Journal 2024年第3期8卷 133-139页

作者： Abisola m.Oladimeji Abayomi Joseph Afe Louis Carillo Courtney Hundley Yufang Zhang Stephen Long Kirstin Short Roger Sealy Janeana White david Persse Bureau of Epidemiology Houston Health DepartmentHoustonTX 77054USA

Background:In the 2022-2023 global outbreak,the United States and state of Texas recorded a total of 31,277 and 3,085 confirmed monkeypox(mpox)cases respectively as of November *** study aims to investigate the demographic characteristics and risk factors of mpox outbreak in Houston and document the epidemiologic control measures implemented with their ***:Houston Health Department received reports of suspected mpox cases via electronic case reports and laboratory reports from healthcare providers within *** were then investigated and reclassified as either positive or negative using DNA polymerase chain reaction *** the reported cases received between may 2022 and January 2023 were included in this study using convenient sampling *** statistics using frequency distribution was used to analyze the sociodemographic,clinical features and travel history of the cases.A two-sided Chi-squared test was used to determine association between mpox test results and risk factors with significant level set at Pmeasures such as community engagement,health education,tracking and contact tracing,vaccination,referrals and laboratory sample logistics support were implemented by the health ***:Out of the total of 1,625 suspected persons investigated for mpox,724(44.6%)tested *** the 724 confirmed cases,male was 700(96.7%),females 20(2.8%),transgender male 1(0.1%),transgender female 3(0.4%).Age groups 30-39 years constituted 43.6%,18-29 years 27.4%,40-49 years 18.2%,50-59 years was 8%.Race distribution of positive cases was Whites 43.4%,African American 38.7%,Asian 1.4%.Risk factors with Pmale gender,age groups 30-39 years and 40-49 years,travel history to mpox endemic areas,recent sexual contact with known or suspected mpox cases,human immunodeficiency virus *** as gay and bisexual were also statistically significant risk factors for mpox inf

关键词： monkeypox mpox Riskfactors Control Tecovirimat Vaccination

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Failure mechanism and simulation for long run-out of the catastrophic rock landslide in the Shanyang Vanadium mine,China

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Journal of mountain Science 2024年第9期21卷 2905-2917页

作者： LIU Yinpeng mumtaz HAIDER david-darnor LAWRENCE LI Tonglu SHEN Wei LI Ping College of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China Observation and Research Station of Water Cycle and Geological Environment for the Chinese Loess Plateau Ministry of EducationZhengning 745399China

On 12th August 2015,a massive rapid long run-out rock landslide occurred in the Shanyang Vanadium mine in Shaanxi Province,China,which claimed the lives of 65 *** heavy rainfalls,earthquakes,and mining blasts were recorded before the ***,the failure mechanism and the cause of the long run-out movement are always in *** this paper,we conducted a detailed field investigation,laboratory tests,block theory analysis,and numerical simulation to investigate the failure and long run-out mechanisms of the *** field investigation results show that the source material of the rock landslide is a huge dolomite wedge block bedding on siliceous shale *** compression tests indicate that the uniaxial compression strength of the intact dolomite is 130-140mPa and the dolomite shows a brittle failure *** to the progressive downward erosion of the gully,the dolomite rock bridge at the slope toe became *** the compression stress in the dolomite bridge increased to surpass its strength,the brittle failure of the bridge *** huge potential energy was released following the disintegration of the landslide,which led to the high acceleration of this rock *** 3D discrete element simulation results suggest that the low intergranular friction contributes to the long run-out movement of this rock landslide.

关键词： Rock landslide Gully erosion Long run-out Wedge block Discrete element method

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Organic heterojunction synaptic device with ultra high recognition rate for neuromorphic computing

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Nano Research 2024年第6期17卷 5614-5620页

作者： Xuemeng Hu Jialin meng Tianyang Feng Tianyu Wang Hao Zhu Qingqing Sun david Wei Zhang Lin Chen School of microelectronics State Key Laboratory of Integrated Chips and SystemsFudan UniversityShanghai 200433China National Integrated Circuit Innovation Center Shanghai 201203China

Traditional computing structures are blocked by the von Neumann bottleneck,and neuromorphic computing devices inspired by the human brain which integrate storage and computation have received more and more ***,a flexible organic device with 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene(C8-BTBT)and 2,9-didecyldinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene(C10-DNTT)heterostructural channel having excellent synaptic behaviors was fabricated on muscovite(mICA)substrate,which has a memory window greater than 20 *** device shows better electrical characteristics than organic field effect transistors with single organic semiconductor ***,the device simulates organism synaptic behaviors successfully,such as paired-pulse facilitation(PPF),long-term potentiation/depression(LTP/LTD)process,and transition from short-term memory(STm)to long-term memory(LTm)by optical and electrical ***,the neuromorphic computing function was verified using the modified National Institute of Standards and Technology(mNIST)pattern recognition,with a recognition rate nearly 100%without *** research proposes a flexible organic heterojunction with the ultra-high recognition rate in mNIST pattern recognition and provides the possibility for future flexible wearable neuromorphic computing devices.

关键词： organic heterojunction neuromorphic computing synapse behaviors optical modulation modified National Institute of Standards and Technology(mNIST)pattern recognition

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