261 research outputs found

    Ischemic stroke destabilizes circadian rhythms

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    © 2008 Meng et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

    HI-SLAM: Monocular Real-time Dense Mapping with Hybrid Implicit Fields

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    In this letter, we present a neural field-based real-time monocular mapping framework for accurate and dense Simultaneous Localization and Mapping (SLAM). Recent neural mapping frameworks show promising results, but rely on RGB-D or pose inputs, or cannot run in real-time. To address these limitations, our approach integrates dense-SLAM with neural implicit fields. Specifically, our dense SLAM approach runs parallel tracking and global optimization, while a neural field-based map is constructed incrementally based on the latest SLAM estimates. For the efficient construction of neural fields, we employ multi-resolution grid encoding and signed distance function (SDF) representation. This allows us to keep the map always up-to-date and adapt instantly to global updates via loop closing. For global consistency, we propose an efficient Sim(3)-based pose graph bundle adjustment (PGBA) approach to run online loop closing and mitigate the pose and scale drift. To enhance depth accuracy further, we incorporate learned monocular depth priors. We propose a novel joint depth and scale adjustment (JDSA) module to solve the scale ambiguity inherent in depth priors. Extensive evaluations across synthetic and real-world datasets validate that our approach outperforms existing methods in accuracy and map completeness while preserving real-time performance.Comment: Accepted by IEEE Robotics and Automation Letter

    Outage Analysis for Intelligent Reflecting Surface Assisted Vehicular Communication Networks

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    Vehicular communication is an important application of the fifth generation of mobile communication systems (5G). Due to its low cost and energy efficiency, intelligent reflecting surface (IRS) has been envisioned as a promising technique that can enhance the coverage performance significantly by passive beamforming. In this paper, we analyze the outage probability performance in IRS-assisted vehicular communication networks. We derive the expression of outage probability by utilizing series expansion and central limit theorem. Numerical results show that the IRS can significantly reduce the outage probability for vehicles in its vicinity. The outage probability is closely related to the vehicle density and the number of IRS elements, and better performance is achieved with more reflecting elements

    Comparison of progressive collapse resistance of frame with specially shaped columns and frame with rectangular columns

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    Konstrukcije okvira od armiranog betona (RC - reinforced concrete) s posebno oblikovanim stupovima i RC konstrukcije okvira s pravokutnim stupovima su različite vrste konstrukcija s različitim poprečnim presjecima stupova. Predlaže se model za analizu progresivnog kolapsa RC okvira primjenom elementa greda-stup i veznog elementa na temelju programa OpenSees. Simulirao se progresivni kolaps eksperimentalnog okvira i rezultati proračuna su se poklapali s rezultatima dobivenim eksperimentom. Karakteristike progresivnog kolapsa okvira s posebno oblikovanim stupovima analizirale su se usporedbom otpora progresivnom kolapsu jednog okvira s posebno oblikovanim stupovima i onog s tri okvira s pravokutnim stupovima koji su konstruirani u skladu s tri različita principa. Vidjelo se iz rezultata da su otpor progresivnom kolapsu okvira s posebno oblikovanim stupovima i okvira s pravokutnim stupovima s istom armaturom pod istim seizmičkim ojačanjem, konstrukcijom i uvjetima primjene bili jednaki. Okvir s posebno oblikovanim stupovima bolje je reagirao u otporu na progresivni kolaps.RC frame structures with specially shaped columns and RC frame structures with rectangular columns are different types of structures with different column sections. A progressive collapse analysis model of RC frames was proposed using the beam-column element and joint element based on the program OpenSees. Progressive collapse performance of the experimental frame was simulated and the calculation results were in good agreement with the experimental results. The characteristics of progressive collapse performance of frames with specially shaped columns were studied by comparing the progressive collapse resistance of one frame with specially shaped columns with that of three frames with rectangular columns which were designed in accordance with three different principles. It was observed from the results that the progressive collapse resistance of frame with specially shaped columns and frames with rectangular columns with the same reinforcement under the same seismic fortification, design and application conditions were equivalent. The frame with specially shaped columns had a superior performance to resist progressive collapse

    Analysis of tsunami effect and structural response

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    Tsunami predstavlja jednu od ozbiljnih prirodnih katastrofa u svijetu, koja rezultira ogromnom horizontalnom potisnom silom na obalne zgrade, dovodeći do trenutnog urušavanja velikog broja zgrada što uzrokuje velike nesreće i ekonomske gubitke. U ovom radu, uz podršku hidrodinamičkog softvera FLOW-3D, primjenom metode Volumena fluida (VOF), zahvaćena je slobodna dodirna površina i primijenjen model idealnog pojedinačnog vala u svrhu simuliranja valova tsunamija. Zasnivajući se na simuliranju i analizi trodimenzijskog numeričkog modela okvira konstrukcije od armiranog betona pod udarnom silom tsunami valova, može se ustanoviti veličina i raspodjela sila tsunamija. Osim toga, primjenom softvera ANSYS za analizu konačnih elemenata, dobiven je model konačnih elemenata za konstrukciju okvira kako bi se analizirala reakcija konstrukcije od armiranog betona na udar tsunami sila te poduzele odgovarajuće konstrukcijske protumjere, tehničke preventivne i kontrolne mjere te tako oduprlo silama tsunamija.Tsunami is one of the serious natural disasters in the world, which produce huge horizontal thrust on costal buildings, resulting in a large number of houses collapsed instantaneously, causing serious casualties and economic losses. In this paper, based on support from the hydrodynamic software FLOW-3D, the method of Volume of Fluid (VOF) is utilized to capture free interface, and the ideal solitary wave model is applied to simulate tsunami waves. Based on simulating and analysing the three-dimensional numerical model of reinforced concrete frame structure under the impact of tsunami waves, the magnitude and distribution of tsunami forces can be obtained. Moreover, the finite element analysis software ANSYS is adopted to set up finite element model for the frame structure, so as to analyse the response of the reinforced concrete frame structure under the impact of tsunami forces, and to put forward related structural countermeasures, engineering prevention and control measures to resist tsunami forces

    Experimental Study of the Seismic Performance of L-Shaped Columns with 500 MPa Steel Bars

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    Based on tests on six L-shaped RC columns with 500 MPa steel bars, the effect of axial compression ratios and stirrup spacing on failure mode, bearing capacity, displacement, and curvature ductility of the specimens is investigated. Test results show that specimens with lower axial load and large stirrup characteristic value (larger than about 0.35) are better at ductility and seismic performance, while specimens under high axial load or with a small stirrup characteristic value (less than about 0.35) are poorer at ductility; L-shaped columns with 500 MPa steel bars show better bearing capacity and ductility in comparison with specimens with HRB400 steel bars

    Finite-time stability for fractional-order fuzzy neural network with mixed delays and inertial terms

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    This paper explored the finite-time stability (FTS) of fractional-order fuzzy inertial neural network with mixed delays. First, the dimension of the model was reduced by the order reduction method. Second, by leveraging the fractional-order finite-time stability theorem, fractional calculus and inequality methods, we established some sufficient conditions to guarantee the FTS of the model under feasible delay-dependent feedback controller and delay-dependent adaptive controller, respectively. Additionally, we derived the settling times (STs) for each control strategy. Finally, we provided two examples to substantiate our findings
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