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Lateral earth pressure of granular backfills on retaining walls with expanded polystyrene geofoam inclusions under limited surcharge loading 被引量:1
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作者 Kewei Fan Guangqing Yang +2 位作者 Weilie Zou Zhong Han Yang Shen 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1388-1397,共10页
Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,t... Existing studies have focused on the behavior of the retaining wall equipped with expanded polystyrene(EPS)geofoam inclusions under semi-infinite surcharge loading rather than limited surcharge loading.In this paper,the failure mode and the earth pressure acting on the rigid retaining wall with EPS geofoam inclusions and granular backfills(henceforth referred to as EPS-wall),under limited surcharge loading are investigated through two-and three-dimensional model tests.The testing results show that different from the sliding of almost all the backfill in the EPS-wall under semi-infinite surcharge loading,only an approximately triangular backfill slides in the wall under limited surcharge loading.The distribution of the lateral earth pressure on the EPS-wall under limited surcharge loading is non-linear,and the distribution changes from the increase of the wall depth to the decrease with the increase of the limited surcharge loading.An approach based on the force equilibrium of a differential element is developed to predict the lateral earth pressure behind the EPS-wall subjected to limited surcharge loading,and its performance was fully validated by the three-dimensional model tests. 展开更多
关键词 Retaining wall Expanded polystyrene(EPS)geofoam limited surcharge loading Lateral earth pressure Model test Prediction
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Performance Limits and Advancements in Single 2D Transition Metal Dichalcogenide Transistor
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作者 Jing Chen Ming-Yuan Sun +8 位作者 Zhen-Hua Wang Zheng Zhang Kai Zhang Shuai Wang Yu Zhang Xiaoming Wu Tian-Ling Ren Hong Liu Lin Han 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第12期134-188,共55页
Two-dimensional(2D)transition metal dichalcogenides(TMDs)allow for atomic-scale manipulation,challenging the conventional limitations of semiconductor materials.This capability may overcome the short-channel effect,sp... Two-dimensional(2D)transition metal dichalcogenides(TMDs)allow for atomic-scale manipulation,challenging the conventional limitations of semiconductor materials.This capability may overcome the short-channel effect,sparking significant advancements in electronic devices that utilize 2D TMDs.Exploring the dimension and performance limits of transistors based on 2D TMDs has gained substantial importance.This review provides a comprehensive investigation into these limits of the single 2D-TMD transistor.It delves into the impacts of miniaturization,including the reduction of channel length,gate length,source/drain contact length,and dielectric thickness on transistor operation and performance.In addition,this review provides a detailed analysis of performance parameters such as source/drain contact resistance,subthreshold swing,hysteresis loop,carrier mobility,on/off ratio,and the development of p-type and single logic transistors.This review details the two logical expressions of the single 2D-TMD logic transistor,including current and voltage.It also emphasizes the role of 2D TMD-based transistors as memory devices,focusing on enhancing memory operation speed,endurance,data retention,and extinction ratio,as well as reducing energy consumption in memory devices functioning as artificial synapses.This review demonstrates the two calculating methods for dynamic energy consumption of 2D synaptic devices.This review not only summarizes the current state of the art in this field but also highlights potential future research directions and applications.It underscores the anticipated challenges,opportunities,and potential solutions in navigating the dimension and performance boundaries of 2D transistors. 展开更多
关键词 Two-dimensional transistors Dimension limits Performance limits Memory devices Artificial synapses
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Inhibition of the NF-κB Signaling Pathway Improves Cigarette Mainstream Smoke-Induced Lung Injury and Gut Microbiota Disturbance
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作者 Hong Huang Shengjie Li +6 位作者 Lifang Zeng Yan Zhang Ying Chen Yanbing Ma Jing Wei Changwei Zou Tingtao Chen 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2024年第6期676-681,共6页
Currently,cigarette smoke(CS)remains a major contributor to disease morbidity and mortality.CS can be divided into cigarette mainstream smoke(CMS)and side-stream smoke,depending on where it is produced by burning toba... Currently,cigarette smoke(CS)remains a major contributor to disease morbidity and mortality.CS can be divided into cigarette mainstream smoke(CMS)and side-stream smoke,depending on where it is produced by burning tobacco^([1]).CMS is inhaled by smokers from the filter end during cigarette combustion and is strongly associated with the development of several diseases^([2-4]). 展开更多
关键词 smoke CMS CIGARETTE
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A Stroke-Limitation AMD Control System with Variable Gain and Limited Area for High-Rise Buildings
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作者 Zuo-Hua Li Qing-Gui Wu +1 位作者 Jun Teng Chao-Jun Chen 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第1期865-884,共20页
Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a ... Collisions between a moving mass and an anti-collision device increase structural responses and threaten structural safety.An active mass damper(AMD)with stroke limitations is often used to avoid collisions.However,a strokelimited AMD control system with a fixed limited area shortens the available AMD stroke and leads to significant control power.To solve this problem,the design approach with variable gain and limited area(VGLA)is proposed in this study.First,the boundary of variable-limited areas is calculated based on the real-time status of the moving mass.The variable gain(VG)expression at the variable limited area is deduced by considering the saturation of AMD stroke.Then,numerical simulations of a stroke-limited AMD control system with VGLA are conducted on a high-rise building structure.These numerical simulations show that the proposed approach has superior strokelimitation performance compared with a stroke-limited AMD control system with a fixed limited area.Finally,the proposed approach is validated through experiments on a four-story steel frame. 展开更多
关键词 High-rise buildings active control stroke limitations variable gain variable limited area
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Supplementary Information to“Balancing the quantum speed limit and instantaneous energy cost in adiabatic quantum evolution”
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作者 徐建文 张宇佳 +9 位作者 郑文 蔡浩阳 周浩宇 李先科 廖绪东 张钰 李邵雄 兰栋 谭新生 于扬 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第4期13-18,共6页
I.SUPPLEMENTARY NOTE 1:THEORETICAL MATERIALS.The quantum speed limit(QSL)is essential for quantum computing and quantum communication,referring to the minimum time required for a quantum system to evolve from one stat... I.SUPPLEMENTARY NOTE 1:THEORETICAL MATERIALS.The quantum speed limit(QSL)is essential for quantum computing and quantum communication,referring to the minimum time required for a quantum system to evolve from one state to another.Two well-known forms of the QSL are the Mandelstam-Tamm(MT)relation TqsL≥πh/2△E[S1]and the Margolus-Levitin(ML)relation TqsL≥πh/2(E)[S2]where Tqst is denoted as the QSL time,h is the reduced Planck's constant,△E is the energy uncertainty(standard deviation)of the system,and(E)is the average energy of the system above its ground state.Both of relations provide a lower bound on the evolution time. 展开更多
关键词 QUANTUM limit SYSTEM
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Physical, Mental and Social Wellbeing and Quality of Life among Current Smokers
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作者 Steven A. Branstetter 《Health》 2024年第11期985-993,共9页
Cigarette smoking has known negative effects on physical and mental health. Over 16 million Americans suffer from smoking-related illnesses, and one-third of individuals with mental health issues are also cigarette sm... Cigarette smoking has known negative effects on physical and mental health. Over 16 million Americans suffer from smoking-related illnesses, and one-third of individuals with mental health issues are also cigarette smokers. Both physical and mental health are associated with measures of overall quality of life, a critical outcome that can influence treatment, intervention, and prevention decision-making. However, the direct relation between smoking and quality of life is not clear and requires further investigation. The present study utilized data from 34,309 adults who participated in Wave 5 of the Population Assessment of Tobacco and Health (PATH) to examine the relation between smoking and quality of life while considering the mediating effects of physical and mental health, and the moderating effect of social satisfaction. Using Conditional Process Analyses to integrate mediation and moderation approaches, the present study found that smoking had indirect associations with quality of life mediated through both physical and mental health and that social satisfaction moderated these relationships. Additionally, smoking had an independent direct effect on quality of life that was not moderated by social satisfaction. Results suggest the negative impacts associated with smoking reach beyond its effect on physical, social and mental well-being. 展开更多
关键词 Cigarette Smoking Quality of Life Physical Health Mental Health WELL-BEING
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Cosmology-Independent Photon Mass Limits from Localized Fast Radio Bursts by Using Artificial Neural Networks
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作者 冉景遇 王宝 魏俊杰 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第5期177-183,共7页
A hypothetical photon mass m_(γ) can produce a frequency-dependent vacuum dispersion of light, which leads to an additional time delay between photons with different frequencies when they propagate through a fixed di... A hypothetical photon mass m_(γ) can produce a frequency-dependent vacuum dispersion of light, which leads to an additional time delay between photons with different frequencies when they propagate through a fixed distance. The dispersion measure and redshift measurements of fast radio bursts(FRBs) have been widely used to constrain the rest mass of the photon. However, all current studies analyzed the effect of the frequency-dependent dispersion for massive photons in the standard ΛCDM cosmological context. In order to alleviate the circularity problem induced by the presumption of a specific cosmological model based on the fundamental postulate of the masslessness of photons, here we employ a new model-independent smoothing technique, artificial neural network(ANN), to reconstruct the Hubble parameter H(z) function from 34 cosmic-chronometer measurements.By combining observations of 32 well-localized FRBs and the H(z) function reconstructed by ANN, we obtain an upper limit of m_(γ) ≤ 3.5 × 10^(-51)kg, or equivalently m_(γ) ≤ 2.0 × 10^(-15)eV/c^(2)(m_(γ) ≤ 6.5 × 10^(-51)kg, or equivalently m_(γ) ≤ 3.6 × 10^(-15)eV/c_(2)) at the 1σ(2σ) confidence level. This is the first cosmology-independent photon mass limit derived from extragalactic sources. 展开更多
关键词 DISPERSION limit INDEPENDENT
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Parity-Time symmetry helps breaking a new limit
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作者 Wenjie Wan Xiaoshun Jiang 《Light(Science & Applications)》 SCIE EI CSCD 2024年第11期2436-2437,共2页
Parity-Time(PT)symmetry is an emerging concept in quantum mechanics where non-Hermitian Hamiltonians can exhibit real eigenvalues.Now,PT symmetric optical microresonators have been demonstrated to break the bandwidth-... Parity-Time(PT)symmetry is an emerging concept in quantum mechanics where non-Hermitian Hamiltonians can exhibit real eigenvalues.Now,PT symmetric optical microresonators have been demonstrated to break the bandwidth-efficiency limit for nonlinear optical signal processing. 展开更多
关键词 SYMMETRY limit BREAKING
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Small-scale fire tests in the underwater tunnel section model with new sidewall smoke extraction
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作者 Shunyu Yue Ruifeng Miao +2 位作者 Huihang Cheng Maohua Zhong Xiujun Yang 《Deep Underground Science and Engineering》 2024年第2期247-254,共8页
The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the t... The Shenzhen–Zhongshan Bridge is a 24‐km‐long bridge and tunnel system,including a 6.8-km-long super cross section subsea tunnel.To solve the smoke exhaust problem of a super large cross-section subsea tunnel,the tunnel has a new smoke exhaust system that combines a horizontal smoke exhaust cross section at the top and sidewall smoke exhaust holes.In order to evaluate the potential fire hazards of this type of tunnel,a 1:30 tunnel model was established and 140 smallscale experiments on underwater tunnel fires were conducted.By changing the fire power,fire location,and fan operation mode,different scenarios of submarine immersed tunnel fire were simulated and the related key parameters such as fire smoke diffusion behavior and smoke temperature distribution were studied.On this basis,the optimal smoke control strategy was proposed for different fire scenarios.The research results indicate that the new smoke exhaust system can fully utilize the smoke flow characteristics,significantly improve smoke exhaust efficiency,and increase available evacuation time,thus further enhancing the fire safety of super large cross-section subsea tunnels. 展开更多
关键词 sidewall smoke extraction system small‐scale fire tests smoke control
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Study on the Influence of Setting Parameters of Tunnel Centralized Smoke Extraction System on Fire Smoke Flow and Temperature Decay
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作者 Zhisheng Xu SohailMahmood Zihan Yu 《Frontiers in Heat and Mass Transfer》 EI 2024年第3期791-816,共26页
The centralized smoke exhaust system of shield tunnel is an important determinant for tunnel fire safety,and the use of different design parameters of the tunnel smoke exhaust system will affect the smoke exhaust effe... The centralized smoke exhaust system of shield tunnel is an important determinant for tunnel fire safety,and the use of different design parameters of the tunnel smoke exhaust system will affect the smoke exhaust effect in the tunnel,and the influence of different design parameters on the smoke exhaust effect and temperature attenuation of the tunnel can help engineers in designing a more effective centralized smoke exhaust system for the tunnel.In this paper,the Fire Dynamic Simulator(FDS)is utilized to examine smoke exhaust vent settings for a centralized exhaust system in shield tunnel with both flat and sloped conditions,including slopes of+4.5%and−4.5%,under a 30MWfire power with a 150m^(3)/s smoke exhaust rate.The results suggest that maintaining a vent spacing of 60m and a vent size of 4.0 m×1.5 m is a reasonable configuration for centralized smoke exhaust systems in both flat and slope shield tunnels.This choice helpsminimize construction costs and prevent excessive smoke accumulation.It also promotes favorable conditions for maintaining temperature distribution at 2-m height,visibility,smoke spread distance,and temperature below the ceiling,all below the threshold values,while ensuring high smoke extraction efficiency.However,in the slope section,the chimney effect can disrupt exhaust efficiency,visibility,ceiling temperature,and temperature distribution at a height of 2 m.Employing different opening methods,such as having 2 vents up and 4 vents down in a+4.5%slope and 4 vents up and 2 vents down in a−4.5%slope,can help mitigate these effects.Furthermore,the temperature decay formula for shield tunnels follows a bi-exponential decay pattern,and different design parameters of centralized smoke exhaust systems have minimal effects on temperature decay in shield tunnels. 展开更多
关键词 smoke exhaust setting smoke spread efficiency temperature decay
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An Improved YOLOv5s-Based Smoke Detection System for Outdoor Parking Lots
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作者 Ruobing Zuo Xiaohan Huang +1 位作者 Xuguo Jiao Zhenyong Zhang 《Computers, Materials & Continua》 SCIE EI 2024年第8期3333-3349,共17页
In the rapidly evolving urban landscape,outdoor parking lots have become an indispensable part of the city’s transportation system.The growth of parking lots has raised the likelihood of spontaneous vehicle combus-ti... In the rapidly evolving urban landscape,outdoor parking lots have become an indispensable part of the city’s transportation system.The growth of parking lots has raised the likelihood of spontaneous vehicle combus-tion,a significant safety hazard,making smoke detection an essential preventative step.However,the complex environment of outdoor parking lots presents additional challenges for smoke detection,which necessitates the development of more advanced and reliable smoke detection technologies.This paper addresses this concern and presents a novel smoke detection technique designed for the demanding environment of outdoor parking lots.First,we develop a novel dataset to fill the gap,as there is a lack of publicly available data.This dataset encompasses a wide range of smoke and fire scenarios,enhanced with data augmentation to ensure robustness against diverse outdoor conditions.Second,we utilize an optimized YOLOv5s model,integrated with the Squeeze-and-Excitation Network(SENet)attention mechanism,to significantly improve detection accuracy while maintaining real-time processing capabilities.Third,this paper implements an outdoor smoke detection system that is capable of accurately localizing and alerting in real time,enhancing the effectiveness and reliability of emergency response.Experiments show that the system has a high accuracy in terms of detecting smoke incidents in outdoor scenarios. 展开更多
关键词 YOLOv5s smoke detection deep learning SENet
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Speed limit effect during lane change in a two-lane lattice model under V2X environment
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作者 金灿 彭光含 聂方彦 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期718-722,共5页
Speed limit measures are ubiquitous due to the complexity of the road environment,which can be supplied with the help of vehicle to everything(V2X)communication technology.Therefore,the influence of speed limit on tra... Speed limit measures are ubiquitous due to the complexity of the road environment,which can be supplied with the help of vehicle to everything(V2X)communication technology.Therefore,the influence of speed limit on traffic system will be investigated to construct a two-lane lattice model accounting for the speed limit effect during the lane change process under V2X environment.Accordingly,the stability condition and the mKdV equation are closely associated with the speed limit effect through theory analysis.Moreover,the evolution of density and hysteresis loop is simulated to demonstrate the positive role of the speed limit effect on traffic stability in the cases of strong reaction intensity and high limited speed. 展开更多
关键词 traffic flow lattice model speed limit
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Study of the Influence of the Distance between Smoke Outlets and Fire Source on Smoke Flow Characteristics in Tunnel Fires
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作者 Liang Yi Zhiqiang Lei +2 位作者 Zhisheng Xu Yaolong Yin Houlin Ying 《Frontiers in Heat and Mass Transfer》 EI 2024年第4期977-996,共20页
This paper explores the smoke flow characteristics in tunnel fires,giving a particular emphasis on the effects of different distances between the smoke outlets and the fire source.It examines the smoke behavior under ... This paper explores the smoke flow characteristics in tunnel fires,giving a particular emphasis on the effects of different distances between the smoke outlets and the fire source.It examines the smoke behavior under different conditions,including variations in heat release rates,exhaust volumetric flow rates,spacing between smoke outlets,and the longitudinal fire source positions.Results indicate that altering the fire source positions and the smoke outlets in the tunnel leads to variations in the properties of smoke flow both the fire source upstream and downstream;the distance between fire source and smoke outlet increases gradually,airflow rate decreases initially and eventually reaches a stable state.Similarly,smoke mass flow rate exhibits an increasing trend that eventually reaches a stable state.Moreover,the heat exchange between the tunnel walls and hot smoke increases as the smoke outlet moves further away from the fire source.This interaction leads to a reduction in the heat exhaust coefficient and a decrease in the distance the smoke spreads.This study investigates the impact of altering the relative longitudinal fire source positions and smoke outlet on smoke flow characteristics by numerical simulation.A theoretical analytical method is used to give a predictive model for the heat exhaust coefficient and the smoke spreading distance.This research can support the theory and technical process of tunnel smoke exhaust prevention and control. 展开更多
关键词 Tunnel fire numerical simulation centralized smoke exhaust heat exhaust coefficient smoke spreading distance
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Proteomic response of Phaeocystis globosa to nitrogen limitation
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作者 Haisu LIU Ruiwang WEI +2 位作者 Qiangyong LEI Lei CUI Songhui LÜ 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第1期141-149,共9页
Phaeocystis globosa is an important unicellular eukaryotic alga that can also form colonies.P.globosa can cause massive harmful algal blooms and plays an important role in the global carbon or sulfur cycling.Thus far,... Phaeocystis globosa is an important unicellular eukaryotic alga that can also form colonies.P.globosa can cause massive harmful algal blooms and plays an important role in the global carbon or sulfur cycling.Thus far,the ecophysiology of P.globosa has been investigated by numerous studies.However,the proteomic response of P.globosa to nitrogen depletion remains largely unknown.We compared four protein preparation methods of P.globosa for two-dimensional electrophoresis(2-DE)(Urea/Triton X-100 with trichloroacetic acid(TCA)/acetone precipitation;TCA/acetone precipitation;Radio Immuno Precipitation Assay(RIPA)with TCA/acetone precipitation;and Tris buffer).Results show that the combination of RIPA with TCA/acetone precipitation had a clear gel background and showed the best protein spot separation effect,based on which the proteomic response to nitrogen depletion was studied using 2-DE.In addition,we identified six differentially expressed proteins whose relative abundance increased or decreased more than 1.5-fold(P<0.05).Most proteins could not be identified,which might be attributed to the lack of genomic sequences of P.globosa.Under nitrogen limitation,replication protein-like,RNA ligase,and sn-glycerol-3-phosphate dehydrogenase were reduced,which may decrease the DNA replication level and ATP production in P.globosa cells.The increase of endonucleaseⅢand transcriptional regulator enzyme may affect the metabolic and antioxidant function of P.globosa cells and induce cell apoptosis.These findings provide a basis for further proteomic study of P.globosa and the optimization of protein preparation methods of marine microalgae. 展开更多
关键词 Phaeocystis globosa nitrogen limitation proteomic response two-dimensional electrophoresis
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U-Net Inspired Deep Neural Network-Based Smoke Plume Detection in Satellite Images
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作者 Ananthakrishnan Balasundaram Ayesha Shaik +1 位作者 Japmann Kaur Banga Aman Kumar Singh 《Computers, Materials & Continua》 SCIE EI 2024年第4期779-799,共21页
Industrial activities, through the human-induced release of Green House Gas (GHG) emissions, have beenidentified as the primary cause of global warming. Accurate and quantitative monitoring of these emissions isessent... Industrial activities, through the human-induced release of Green House Gas (GHG) emissions, have beenidentified as the primary cause of global warming. Accurate and quantitative monitoring of these emissions isessential for a comprehensive understanding of their impact on the Earth’s climate and for effectively enforcingemission regulations at a large scale. This work examines the feasibility of detecting and quantifying industrialsmoke plumes using freely accessible geo-satellite imagery. The existing systemhas so many lagging factors such aslimitations in accuracy, robustness, and efficiency and these factors hinder the effectiveness in supporting timelyresponse to industrial fires. In this work, the utilization of grayscale images is done instead of traditional colorimages for smoke plume detection. The dataset was trained through a ResNet-50 model for classification and aU-Net model for segmentation. The dataset consists of images gathered by European Space Agency’s Sentinel-2 satellite constellation from a selection of industrial sites. The acquired images predominantly capture scenesof industrial locations, some of which exhibit active smoke plume emissions. The performance of the abovementionedtechniques and models is represented by their accuracy and IOU (Intersection-over-Union) metric.The images are first trained on the basic RGB images where their respective classification using the ResNet-50model results in an accuracy of 94.4% and segmentation using the U-Net Model with an IOU metric of 0.5 andaccuracy of 94% which leads to the detection of exact patches where the smoke plume has occurred. This work hastrained the classification model on grayscale images achieving a good increase in accuracy of 96.4%. 展开更多
关键词 smoke plume ResNet-50 U-Net geo satellite images early warning global monitoring
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Seismic-induced surficial failure of cohesive slopes using three-dimensional limit analysis:A case study of the Wangjiayan landslide in Beichuan, China
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作者 Gao Yufeng Liu Yang +1 位作者 Geng Weijuan Zhang Fei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第3期537-545,共9页
A seismic-induced landslide is a common geological catastrophe that occurs in nature.The Wangjiayan landslide,which was triggered by the Wenchuan earthquake,is a typical case in point.The Wanjiayan landslide caused ma... A seismic-induced landslide is a common geological catastrophe that occurs in nature.The Wangjiayan landslide,which was triggered by the Wenchuan earthquake,is a typical case in point.The Wanjiayan landslide caused many casualties and resulted in enormous property loss.This study constructs a simple surficial failure model based on the upper bound approach of three-dimensional(3D)limit analysis to evaluate the slope stability of the Wangjiayan case,while a traditional two-dimensional(2D)analysis is also conducted as a reference for comparison with the results of the 3D analysis.A quasi-static calculation is used to study the effect of the earthquake in terms of horizontal ground acceleration,while a parametric study is conducted to evaluate the critical cohesion of slopes.Rather than employing a 3D analysis,using the 2D analysis yields an underestimation regarding the safety factor.In the Wangjiayan landslide,the difference in the factors of safety between the 3D and 2D analyses can reach 20%.The sliding surface morphology as determined by the 3D method is similar to actual morphology,and the parameters of both are also compared to analyze the reliability of the proposed 3D method. 展开更多
关键词 LANDSLIDE Wenchuan earthquake surficial failure limit analysis stability QUASI-STATIC
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THE LIMIT CYCLE BIFURCATIONS OF A WHIRLING PENDULUM WITH PIECEWISE SMOOTH PERTURBATIONS
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作者 杨纪华 《Acta Mathematica Scientia》 SCIE CSCD 2024年第3期1115-1144,共30页
This paper deals with the problem of limit cycles for the whirling pendulum equation x=y,y=sin x(cosx-r)under piecewise smooth perturbations of polynomials of cos x,sin x and y of degree n with the switching line x=0.... This paper deals with the problem of limit cycles for the whirling pendulum equation x=y,y=sin x(cosx-r)under piecewise smooth perturbations of polynomials of cos x,sin x and y of degree n with the switching line x=0.The upper bounds of the number of limit cycles in both the oscillatory and the rotary regions are obtained using the Picard-Fuchs equations,which the generating functions of the associated first order Melnikov functions satisfy.Furthermore,the exact bound of a special case is given using the Chebyshev system.At the end,some numerical simulations are given to illustrate the existence of limit cycles. 展开更多
关键词 whirling pendulum limit cycle Melnikov function Picard-Fuchs equation Chebyshev system
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The Limits of Etiological Diagnosis of Convulsions in Children at the Bangui Pediatric Hospital
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作者 Simplice Cyriaque Kango Marie Christine Awa Sepou Yanza +2 位作者 Belly Komangoya Francky Kouandongui Bangue Songrou Jean Chrysostome Gody 《Open Journal of Pediatrics》 2024年第6期1117-1125,共9页
Introduction: Convulsions are a frequent cause of admission to paediatric wards in countries with limited resources, and a major cause of neurological and cognitive sequelae. In sub-Saharan Africa, the aetiology of fe... Introduction: Convulsions are a frequent cause of admission to paediatric wards in countries with limited resources, and a major cause of neurological and cognitive sequelae. In sub-Saharan Africa, the aetiology of febrile convulsions is dominated by infections of the central nervous system. A detailed clinical examination and laboratory and imaging tests are carried out to identify the cause of the disease. Computed tomography is reserved for emergency situations or as a second line of defence, after Magnetic Resonance Imaging (MRI) to look for calcifications. Imaging thus helps to establish the nature of the epileptogenic lesion, specify its extent and guide its therapeutic management. The aim of this study is to clarify the contribution of MRI in the etiological investigation of convulsions in children at the paediatric university hospital, in addition to the usual means of exploration. Patient and Method: This was a cross-sectional, descriptive study from January 2022 to December 2023. We carried out an exhaustive sampling of all children aged between 1 and 59 months admitted for convulsion with fever or not who had undergone complementary examinations for aetiological purposes in relation to our technical platform during the study period. Results: Thirty patients were recruited. Children aged 12 to 59 months were the most represented (69.7%). The sex ratio was 1.30. The mean age was 36 months (range 30 days to 59 months). Of the 30 patients, 21.8% had a history of febrile convulsions. Most of our patients were from Bangui (73.3%). On admission, the majority of patients presented with an elevated temperature ranging from 38.5 degrees Celsius to 39.4 degrees Celsius in 33.1% of cases. The dominant clinical manifestations were tonic-clonic convulsions (53.2%), tonic convulsions (35.3%) and clonic convulsions (11.5%). According to their characteristics, convulsions were complex in 53.7% of cases and simple in 46.3%. Examinations for infectious diseases, tumors or malformation has been ruled out. The anticonvulsants most commonly used were diazepam, phenobarbital and phenytoin. We recorded a 73.3% cure rate and 4 (13.3%) cases of death. Conclusion: The investigation of seizures in search of aetiology outside the usual means in our context still presents difficulties. MRI is the examination of choice for exploring the posterior fossa and midline lesions. Combined with CT, it is better for exploring hemispheric tumours. 展开更多
关键词 limitATIONS Aetiological Diagnosis CONVULSIONS CHILDREN Central African Republic
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Effects of nutrient limitations on the sinking velocity of Thalassiosira weissflogii
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作者 Jie Zhu Qiang Hao +2 位作者 Wei Zhang Yingying Ma Jiangning Zeng 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2024年第6期163-172,共10页
The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,w... The sinking of diatoms is critic al to the formation of oceanic biological pumps and coastal hypoxic zones.However,little is known about the effects of different nutrient restrictions on diatom sinking.In this study,we measured the sinking velocity(SV) of Thalassiosira weissflogii using a new phytoplankton video observation instrument and analyzed major biochemical components under varying nutrient conditions.Our results showed that the SV of T.weissflogii under different nutrient limitation conditions varied substantially.The highest SV of(1.77±0.02) m/d was obtained under nitrate limitation,signific antly surpassing that under phosphate limitation at(0.98±0.13) m/d.As the nutrient limitation was released,the SV steadily decreased to(0.32±0.03) m/d and(0.15±0.05) m/d,respectively.Notably;under conditions with limited nitrate and phosphate concentrations,the SV values of T.weissflogii significantly positively correlated with the lipid content(P <0.001),with R^(2) values of 0.86 and 0.69,respectively.The change of the phytoplankton SV was primarily related to the intracellular compo sition,which is controlled by nutrient conditions but did not significantly correlate with transparent extracellular polymer and biosilica contents.The results of this study help to understand the regulation of the vertical sinking process of diatoms by nutrient restriction and provide new insights into phytoplankton dynamics and their relationship with the marine nutrient structure. 展开更多
关键词 nutrient limitation Thalassiosira weissflogii sinking velocity biochemical component lipid content
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Monolithic Convex Limiting for Legendre-Gauss-Lobatto Discontinuous Galerkin Spectral-Element Methods
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作者 Andrés M.Rueda-Ramírez Benjamin Bolm +1 位作者 Dmitri Kuzmin Gregor J.Gassner 《Communications on Applied Mathematics and Computation》 EI 2024年第3期1860-1898,共39页
We extend the monolithic convex limiting(MCL)methodology to nodal discontinuous Galerkin spectral-element methods(DGSEMS).The use of Legendre-Gauss-Lobatto(LGL)quadrature endows collocated DGSEM space discretizations ... We extend the monolithic convex limiting(MCL)methodology to nodal discontinuous Galerkin spectral-element methods(DGSEMS).The use of Legendre-Gauss-Lobatto(LGL)quadrature endows collocated DGSEM space discretizations of nonlinear hyperbolic problems with properties that greatly simplify the design of invariant domain-preserving high-resolution schemes.Compared to many other continuous and discontinuous Galerkin method variants,a particular advantage of the LGL spectral operator is the availability of a natural decomposition into a compatible subcellflux discretization.Representing a highorder spatial semi-discretization in terms of intermediate states,we performflux limiting in a manner that keeps these states and the results of Runge-Kutta stages in convex invariant domains.In addition,local bounds may be imposed on scalar quantities of interest.In contrast to limiting approaches based on predictor-corrector algorithms,our MCL procedure for LGL-DGSEM yields nonlinearflux approximations that are independent of the time-step size and can be further modified to enforce entropy stability.To demonstrate the robustness of MCL/DGSEM schemes for the compressible Euler equations,we run simulations for challenging setups featuring strong shocks,steep density gradients,and vortex dominatedflows. 展开更多
关键词 Structure-preserving schemes Subcellflux limiting Monolithic convex limiting(MCL) Discontinuous Galerkin spectral-element methods(DGSEMS) Legendre-Gauss-Lobatto(LGL)nodes
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