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Mode coupling with Fabry-Perot modes in photonic crystal slabs
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作者 秦恳 胡鹏 +2 位作者 刘杰 向红 韩德专 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第8期90-94,共5页
Fabry–Perot(FP)modes are a class of fundamental resonances in photonic crystal(PhC)slabs.Owing to their low quality factors,FP modes are frequently considered as background fields with their resonance nature being ne... Fabry–Perot(FP)modes are a class of fundamental resonances in photonic crystal(PhC)slabs.Owing to their low quality factors,FP modes are frequently considered as background fields with their resonance nature being neglected.Nevertheless,FP modes can play important roles in some phenomena,as exemplified by their coupling with guided resonance(GR)modes to achieve bound states in the continuum(BIC).Here,we further demonstrate the genuine resonance mode capability of FP modes PhC slabs.Firstly,we utilize temporal coupled-mode theory to obtain the transmittance of a PhC slab based on the FP modes.Secondly,we construct exceptional points(EPs)in both momentum and parameter spaces through the coupling of FP and GR modes.Furthermore,we identify a Fermi arc connecting two EPs and discuss the far-field polarization topology.This work elucidates that the widespread FPs in PhC slabs can serve as genuine resonant modes,facilitating the realization of desired functionalities through mode coupling. 展开更多
关键词 Fabry–Perot mode photonic crystal slab mode coupling exceptional point
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Moment Redistribution Effect of the Continuous Glass Fiber Reinforced Polymer-Concrete Composite Slabs Based on Static Loading Experiment
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作者 Zhao-Jun Zhang Wen-Wei Wang +4 位作者 Jing-Shui Zhen Bo-Cheng Li De-Cheng Cai Yang-Yang Du Hui Huang 《Structural Durability & Health Monitoring》 EI 2025年第1期105-123,共19页
This study aimed to investigate the moment redistribution in continuous glass fiber reinforced polymer(GFRP)-concrete composite slabs caused by concrete cracking and steel bar yielding in the negative bending moment z... This study aimed to investigate the moment redistribution in continuous glass fiber reinforced polymer(GFRP)-concrete composite slabs caused by concrete cracking and steel bar yielding in the negative bending moment zone.An experimental bending moment redistribution test was conducted on continuous GFRP-concrete composite slabs,and a calculation method based on the conjugate beam method was proposed.The composite slabs were formed by combining GFRP profiles with a concrete layer and supported on steel beams to create two-span continuous composite slab specimens.Two methods,epoxy resin bonding,and stud connection,were used to connect the composite slabs with the steel beams.The experimental findings showed that the specimen connected with epoxy resin exhibited two moments redistribution phenomena during the loading process:concrete cracking and steel bar yielding at the internal support.In contrast,the composite slab connected with steel beams by studs exhibited only one-moment redistribution phenomenon throughout the loading process.As the concrete at the internal support cracked,the bending moment decreased in the internal support section and increased in the midspan section.When the steel bars yielded,the bending moment further decreased in the internal support section and increased in the mid-span section.Since GFRP profiles do not experience cracking,there was no significant decrease in the bending moment of the mid-span section.All test specimens experienced compressive failure of concrete at the mid-span section.Calculation results showed good agreement between the calculated and experimental values of bending moments in the mid-span section and internal support section.The proposed model can effectively predict the moment redistribution behavior of continuous GFRP-concrete composite slabs. 展开更多
关键词 Moment redistribution GFRP-concrete composite slabs bending moment experimental study analysis model
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Numerical analysis of high‑speed railway slab tracks using calibrated and validated 3D time‑domain modelling
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作者 A.F.Esen O.Laghrouche +4 位作者 P.K.Woodward D.Medina‑Pineda Q.Corbisez J.Y.Shih D.P.Connolly 《Railway Engineering Science》 EI 2024年第1期36-58,共23页
Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance frequency.In this paper,the elastic performance of a ... Concrete slabs are widely used in modern railways to increase the inherent resilient quality of the tracks,provide safe and smooth rides,and reduce the maintenance frequency.In this paper,the elastic performance of a novel slab trackform for high-speed railways is investigated using three-dimensional finite element modelling in Abaqus.It is then compared to the performance of a ballasted track.First,slab and ballasted track models are developed to replicate the full-scale testing of track sections.Once the models are calibrated with the experimental results,the novel slab model is developed and compared against the calibrated slab track results.The slab and ballasted track models are then extended to create linear dynamic models,considering the track geodynamics,and simulating train passages at various speeds,for which the Ledsgard documented case was used to validate the models.Trains travelling at low and high speeds are analysed to investigate the track deflections and the wave propagation in the soil,considering the issues associated with critical speeds.Various train loading methods are discussed,and the most practical approach is retained and described.Moreover,correlations are made between the geotechnical parameters of modern high-speed rail and conventional standards.It is found that considering the same ground condition,the slab track deflections are considerably smaller than those of the ballasted track at high speeds,while they show similar behaviour at low speeds. 展开更多
关键词 High-speed railways slab track New ballastless track Ballasted track Critical speeds Finite element modelling Calibration of numerical models
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Effect of temperature gradientinduced periodic deformation of CRTS Ⅲ slab track on dynamic responses of the train-track system
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作者 Wang Jijun Zhang Huanxin +1 位作者 Shi Cheng Wang Meng 《Railway Sciences》 2024年第4期437-452,共16页
Purpose-Temperature is an important load for a ballastless track.However,little research has been conducted on the dynamic responses when a train travels on a ballastless track under the temperature gradient.The dynam... Purpose-Temperature is an important load for a ballastless track.However,little research has been conducted on the dynamic responses when a train travels on a ballastless track under the temperature gradient.The dynamic responses under different temperature gradients of the slab are theoretically investigated in this work.Design/methodology/approach-Considering the moving train,the temperature gradient of the slab,and the gravity of the slab track,a dynamic model for a high-speed train that runs along the CRTS Ⅲ slab track on subgrade is developed by a nonlinear coupled way in Abaqus.Findings-The results are as follows:(1)The upward transmission of the periodic deformation of the slab causes periodic track irregularity.(2)Because of the geometric constraint of limiting structures,the maximum bending stresses of the slab occur near the end of the slab under positive temperature gradients,but in the middle of the slab under negative temperature gradients.(3)The periodic deformation of the slab can induce periodic changes in the interlayer stiffness and contact status,leading to a large vibration of the slab.Because of the vibration-reduction capacity of the fastener and the larger mass of the concrete base,the accelerations of both the slab and concrete base are far less than the acceleration of the rail.Originality/value-This study reveals the influence mechanism of temperature gradient-induced periodic deformation in the dynamic responses of the train-track system,and it also provides a guide for the safe service of CRTS Ⅲ slab track. 展开更多
关键词 Ballastless track CRTSⅢslab track Temperature gradient Periodic deformation Train performance
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Laminated Solid Timber Slab with Transverse Prestressing Using the Strategy of Interleaved Vertical Displacement of Lamellae
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作者 Bianca Bispo dos Reis Jorge Daniel de Melo Moura +1 位作者 Marcos Vinício de Camargo Everaldo Pletz 《Journal of Civil Engineering and Architecture》 2024年第4期186-198,共13页
This article presents a study on the structural behavior of transversely prestressed laminated timber slabs,focusing on an innovative approach:vertically misaligned lamellae.This misalignment,achieved by sliding verti... This article presents a study on the structural behavior of transversely prestressed laminated timber slabs,focusing on an innovative approach:vertically misaligned lamellae.This misalignment,achieved by sliding vertically the wooden lamellae rather than aligning them,enhances the slab’s cross-section moment of inertia,thereby improving load-bearing capacity and stiffness.Testing involved two groups of structural size specimens:one with vertically aligned lamellae(control group)and the other with misaligned lamellae(study group).Results showed the study group exhibited 42%superior stiffness and 10%less load capacity compared to the control.Failures typically occurred individually in the lamellae,particularly in those with defects or lower modulus of elasticity,concentrated in the middle third of the slabs’free span where tensile stresses peak.Despite a higher number of failed lamellae,the study group demonstrated promising performance.Analysis of prestressing bar indicated no damage at all in the thread,suggesting potential for reducing bar diameter.These findings offer crucial insights into applying these slabs in timber construction as well as to any kind of construction. 展开更多
关键词 Transversal prestressed slabs wooden construction plantation wood flexural testing design methodology
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基于SLAB和AFTOX模型的LNG加气站大气环境风险评估
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作者 时任辉 《绿色科技》 2024年第4期193-197,220,共6页
通过设定LNG加气站环境风险事故情景,分别采用SLAB和AFTOX模型模拟预测LNG加气站泄漏和火灾伴生/次生污染物CO的大气环境风险影响程度。结果表明:在风险事故情景下,下风向5 km范围内不同距离的甲烷和CO最大浓度未超过大气毒性终点浓度,... 通过设定LNG加气站环境风险事故情景,分别采用SLAB和AFTOX模型模拟预测LNG加气站泄漏和火灾伴生/次生污染物CO的大气环境风险影响程度。结果表明:在风险事故情景下,下风向5 km范围内不同距离的甲烷和CO最大浓度未超过大气毒性终点浓度,甲烷最大浓度出现在下风向10m处,浓度值为32637.575 mg/m^(3);CO最大浓度出现在下风向5 km处,浓度值为1.746E-4 mg/m^(3)。考虑低温液态LNG的危险性和事故触发具有不确定性,LNG加气站在运营过程中仍需重点做好风险防范措施,编制企业突发环境事件应急预案,建立企业/区域环境风险防控体系,有效防控环境风险。 展开更多
关键词 LNG加气站 slab模型 AFTOX模型 大气环境风险评估
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Exploring the Synergy: Experimental and Theoretical Investigation of Steel and Glass Fiber Reinforced Polymer (GFRP) Reinforced Slab Incorporating Alccofine and M-Sand
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作者 Vijayalakshmi Ravichandran Ravichandran Ramanujam Srinivasan +1 位作者 Saravanan Jagadeesan Prithiviraj Chidambaram 《Open Journal of Civil Engineering》 2024年第3期334-347,共14页
Introduction: This study investigates the Experimental and Theoretical Investigation of Steel and Glass Fiber Reinforced Polymer (GFRP) Reinforced Slab Incorporating Alccofine and M-sand. Objective: Specific objective... Introduction: This study investigates the Experimental and Theoretical Investigation of Steel and Glass Fiber Reinforced Polymer (GFRP) Reinforced Slab Incorporating Alccofine and M-sand. Objective: Specific objectives include evaluating the mechanical properties and structural behaviour of steel and GFRP-reinforced one-way slabs and comparing experimental and theoretical predictions. Methods: Four different mix proportions were arrived at, comprising both conventional concrete and Alccofine-based concrete. In each formulation, a combination of normal river sand and M-sand was utilized. Results: Concrete with Alccofine exhibits superior mechanical properties, while M-sand incorporation minimally affects strength but reduces reliance on natural sand. GFRP-reinforced slabs display distinct brittle behaviour with significant deflections post-cracking, contrasting steel-reinforced slabs’ gradual, ductile failure. Discrepancies between experimental data and design recommendations underscore the need for guideline refinement. Conclusion: Alccofine and M-sand enhance concrete properties, but reinforcement type significantly influences slab behaviour. GFRP-reinforced slabs, though exhibiting lower values than steel, offer advantages in harsh environments, warranting further optimization. 展开更多
关键词 Fiber Reinforced Polymer Alccofine Concrete Structural Behaviour Mechanical Properties One-Way slab Sustainable Construction Materials Alternative Aggregates
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A CLASS OF MULTIWAVELETS AND PROJECTED FRAMES FROM TWO-DIRECTION WAVELETS 被引量:3
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作者 李尤发 杨守志 《Acta Mathematica Scientia》 SCIE CSCD 2014年第2期285-300,共16页
This article aims at studying two-direction refinable functions and two-direction wavelets in the setting R^s, s 〉 1. We give a sufficient condition for a two-direction refinable function belonging to L^2(R^s). The... This article aims at studying two-direction refinable functions and two-direction wavelets in the setting R^s, s 〉 1. We give a sufficient condition for a two-direction refinable function belonging to L^2(R^s). Then, two theorems are given for constructing biorthogonal (orthogonal) two-direction refinable functions in L^2(R^s) and their biorthogonal (orthogonal) two-direction wavelets, respectively. From the constructed biorthogonal (orthogonal) two-direction wavelets, symmetric biorthogonal (orthogonal) multiwaveles in L^2(R^s) can be obtained easily. Applying the projection method to biorthogonal (orthogonal) two-direction wavelets in L^2(R^s), we can get dual (tight) two-direction wavelet frames in L^2(R^m), where m ≤ s. From the projected dual (tight) two-direction wavelet frames in L^2(R^m), symmetric dual (tight) frames in L^2(R^m) can be obtained easily. In the end, an example is given to illustrate theoretical results. 展开更多
关键词 two-direction refinable functions two-direction wavelets MULTIWAVELETS waveletframes biothogonal (orthogonal) SYMMETRY projection method
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Working mechanism of two-direction reinforced composite foundation 被引量:10
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作者 张玲 赵明华 贺炜 《Journal of Central South University of Technology》 EI 2007年第4期589-594,共6页
Based on the discussion about working mechanism of horizontal reinforcement and that of vertical reinforcement,respectively,the working mechanism of two-direction reinforced composite foundation was studied.The enhanc... Based on the discussion about working mechanism of horizontal reinforcement and that of vertical reinforcement,respectively,the working mechanism of two-direction reinforced composite foundation was studied.The enhancing effect of horizontal reinforcement on vertical reinforced composite foundation was analyzed.A simplified calculation method for such two-direction reinforced working system was presented.A model experiment was carried out to validate the proposed method.In the experiment,geocell reinforcement worked as the horizontal reinforcement,while gravel pile composite foundation worked as the vertical reinforcement.The results show that the calculated curve is close to the measured one.The installation of geosynthetic reinforcement can increase the bearing capacity of composite foundation by nearly 68% at normal foundation settlement,which suggests that the enhancing effect by geosynthetic reinforcement should be taken into account in current design/analysis methods. 展开更多
关键词 composite foundation two-direction reinforcement working mechanism bearing capacity
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AXISYMMETRIC BENDING OF TWO-DIRECTIONAL FUNCTIONALLY GRADED CIRCULAR AND ANNULAR PLATES 被引量:6
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作者 Guojun Nie Zheng Zhong 《Acta Mechanica Solida Sinica》 SCIE EI 2007年第4期289-295,共7页
Assuming the material properties varying with an exponential law both in the thick- ness and radial directions, axisymmetric bending of two-directional functionally graded circular and annular plates is studied using ... Assuming the material properties varying with an exponential law both in the thick- ness and radial directions, axisymmetric bending of two-directional functionally graded circular and annular plates is studied using the semi-analytical numerical method in this paper. The deflections and stresses of the plates are presented. Numerical results show the well accuracy and convergence of the method. Compared with the finite element method, the semi-analytical nu- merical method is with great advantage in the computational efficiency. Moreover, study on ax- isymmetric bending of two-directional functionally graded annular plate shows that such plates have better performance than those made of isotropic homogeneous materials or one-directional functionally graded materials. Two-directional functionally graded material is a potential alternative to the one-directional functionally graded material. And the integrated design of materials and structures can really be achieved in two-directional functionally graded materials. 展开更多
关键词 two-directional functionally graded materials circular and annular plates axisym-metric bending semi-analytical numerical method integrated design
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ON TWO-DIRECTION SPATIAL SMOOTHING FOR ESTIMATION ANGLE-OF-DIRECTION OF COHERENT SIGNALS
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作者 赵滨生 陆仲良 《Journal of Electronics(China)》 1990年第3期215-222,共8页
Based on Evans’spatial smoothing preprocessing scheme,a new approach calledtwo-direction spatial smoothing preprocessing method is presented.It is proved that the decorre-lation,the effective aperture and the maximum... Based on Evans’spatial smoothing preprocessing scheme,a new approach calledtwo-direction spatial smoothing preprocessing method is presented.It is proved that the decorre-lation,the effective aperture and the maximum number of distinguishable coherent signals(whenarray size is given)of the new method are better than those of the Evans’method.Simulationresults give a comparison between the eigenvector spectrums produced by the two methods. 展开更多
关键词 Array ANTENNA COHERENT SIGNAL two-direction SPATIAL SMOOTHING method
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Experimental investigation of ultra-early-strength cement-based selfcompacting high strength concrete slabs(URCS)under contact explosions 被引量:1
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作者 Wei Wang Qing Huo +2 位作者 Jian-chao Yang Jian-hui Wang Xing Wang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第6期326-339,共14页
In this paper,UR50 ultra-early-strength cement-based self-compacting high-strength concrete slabs(URCS)have been subjected to contact explosion tests with different TNT charge quality,aiming to evaluate the anti-explo... In this paper,UR50 ultra-early-strength cement-based self-compacting high-strength concrete slabs(URCS)have been subjected to contact explosion tests with different TNT charge quality,aiming to evaluate the anti-explosive performance of URCS.In the experiment,three kinds of ultra-early-strength cement-based reinforced concrete slabs with different reinforcement ratios and a normal concrete slab(NRCS)were used as the control specimen,the curing time of URCS is 28 days and 24 h respectively.The research results show that URCS has a stronger anti-explosion ability than NRCS.The failure mode of URCS under contact explosion is that the front of the reinforced concrete slab explodes into a crater,and the back is spall.With the increase of the charge,the failure mode of the reinforced concrete slab gradually changed to explosive penetration and explosive punching.The experiment results also show that the reinforcement ratio of URCS has little effect on the anti-blast performance,and URCS can reach its anti-blast performance at 28 days after curing for 24 h.On this basis,the damage parameters of URCS for different curing durations were quantified,and an empirical formula for predicting the diameter of the crater and spalling was established. 展开更多
关键词 Ultra-early-strength concrete slabs Blast load Contact blast Blast-resistant performance
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Topography of the 660-km discontinuity within the Izu-Bonin subduction zone and evidence of slab penetration near the Bonin Super Deep Earthquake(~680 km) 被引量:1
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作者 Gang Hao 《Earthquake Science》 2023年第6期458-476,共19页
The Izu-Bonin subduction zone in the Northwest Pacific is an ideal location for understanding mantle dynamics such as cold lithosphere subduction. The slab produces a lateral thermal anomaly, inducing local topographi... The Izu-Bonin subduction zone in the Northwest Pacific is an ideal location for understanding mantle dynamics such as cold lithosphere subduction. The slab produces a lateral thermal anomaly, inducing local topographic changes at the boundary of a post-spinel phase transformation, considered to be the origin of the ‘660-km discontinuity.’ In this study, the short-period(1–2 Hz) S-to-P conversion phase S660P was used to obtain the fine-scale structure of the discontinuity. More than 100 earthquakes that occurred from the 1980s to the 2020s and were recorded by high-quality seismic arrays in the United States and Europe were analyzed. A discontinuity in the ambient mantle with an average depth of ~670 km was found beneath the 300–400-km event zone in the northern Bonin region near 33°N. Meanwhile, the ‘660-km discontinuity’ has been pushed upward, away from the slab, possibly because of a hot upwelling mantle plume. In the central part of the subduction zone, the 660-km discontinuity is depressed to an average depth of(690 ± 5) km within the slab at approximately 150 km below the coldest slab core, indicating a(300 ± 100) ℃ cold anomaly estimated using a post-spinel transformation Clapeyron slope of(-2.0 ± 1.0) MPa/K. In southern Bonin near 28°N, the discontinuity was found to be further depressed at an average depth of(695 ± 5) km below the deepest event and with a focal depth of ~550 km. The discontinuity is located where the slab bends abruptly to become sub-horizontal toward the west-southwest. Near the zone of the isolated Bonin Super Deep Earthquake, which occurred at ~680 km on May 30,2015, the discontinuity is depressed to ~700 km, suggesting a near-vertical penetrating slab and an S-to-P conversion in the coldest slab core, where a large low-temperature anomaly should exist. 展开更多
关键词 Izu-Bonin subduction zone DISCONTINUITY post-spinel transformation S-to-P wave conversion vertical subduction cold slab
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Damage response of conventionally reinforced two-way spanning concrete slab under eccentric impacting drop weight loading 被引量:2
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作者 S.M.Anas Mehtab Alam Mohd Shariq 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第1期12-34,共23页
Reinforced concrete(RC)structures are generally designed to carry quasi-static gravity loads through almost indispensable components namely slab,however,it may be subjected to high intense loads induced from the impac... Reinforced concrete(RC)structures are generally designed to carry quasi-static gravity loads through almost indispensable components namely slab,however,it may be subjected to high intense loads induced from the impact of projectiles generated by the tornado,falling construction equipment,and also from accidental explosions during their construction and service lifespan.Impacts due to rock/boulder falls do occur on the structures located especially in hilly areas.Such loadings are not predictable but may cause severe damage to the slab/structure.It stimulates structural engineers and researchers to investigate and understand the dynamic response of RC structures under such impulsive loading.This research work first investigates the performance of 1000×1000×75 mm^(3)conventionally reinforced two-way spanning normal strength concrete slab with only tension reinforcement(0.88%)under the concentric impact load(1035 N)using the finite element method based computer code,ABAQUS/Explicit-v.6.15.The impact load is delivered to the centroid of the slab using a solid-steel cylindroconical impactor(drop weight)with a flat nose of diameter 40 mm,having a total mass of 105 kg released from a fixed height of 2500 mm.Two popular concrete constitutive models in ABAQUS namely;Holmquist-Johnson-Cook(HJC)and Concrete Damage Plasticity(CDP),with strain rate effects as per fib MODEL CODE 2010,are used to model the concrete material behavior to impact loading and to simulate the damage to the slab.The slab response using these two models is analyzed and compared with the impact test results.The strain rate effect on the reinforcing steel bars has been incorporated in the analysis using the Malvar and Crawford(1998)approach.A classical elastoplastic kinematic idealization is considered to model the steel impactor and support system.Results reveal that the HJC model gives a little overestimation of peak displacement,maximum acceleration,and damage of the slab while the predictions given by the CDP model are in reasonable agreement with the experimental test results/observations available in the open literature.Following the validation of the numerical model,analyses have been extended to further investigate the damage response of the slab under eccentric impact loadings.In addition to the concentric location(P1)of the impacting device,five locations on a quarter of the slab i.e.,two along the diagonal(P2&P3),the other two along the mid-span(P4&P5),and the last one(P6)between P3 and P5,covering the entire slab,are considered.Computational results have been discussed and compared,and the evaluation of the most damaging location(s)of the impact is investigated.It has been found that the most critical location of the impact is not the centroid of the slab but the eccentric one with the eccentricity of 1/6th of the span from the centroid along the mid-span section. 展开更多
关键词 RC slabs Impact loading Eccentric impacts Concrete models Finite element analysis Damage profiles Stresses Peak acceleration Failure modes Damage dissipation energy CRACKING Drop-weight locations
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The dynamic response and damage models of rebar reinforced polymer slabs subjected to contact and near-field explosions
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作者 Hao-nan Zhao Hong-yuan Fang Xiao-hua Zhao 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第10期330-342,共13页
Non aqueous reactive polymer materials produced by the reaction of isocyanate and polyol have been widely used in infrastructure construction,which may be subjected to explosion loads during complex service conditions... Non aqueous reactive polymer materials produced by the reaction of isocyanate and polyol have been widely used in infrastructure construction,which may be subjected to explosion loads during complex service conditions.The blast response of composite materials is a crucial aspect for applications in engineering structures potentially subjected to extreme loadings.In this work,damage caused to rebar reinforced polymer slabs by surface explosive charges was studied experimentally and numerically.A total of 6 field tests were carried out to investigate the performances of the failure modes of rebar reinforced polymer slabs under contact and near-field explosions.The influence of explosive quantity(10-40 g)and stand-off distances(0-20 cm)at the damage modes were studied.The results show that the failure modes of rebar reinforced polymer slabs under near-field explosion mainly were bending and surface spalling,while under the impact of contact explosion,the failure modes were craters of the top surface,spalling of the bottom surface,and middle perforation.Furthermore,a detailed fully coupled model was developed and validated with the test data.The influences of explosive quantity and slab thickness on rebar reinforced polymer slabs under contact explosion were studied.Based on this,the calculation formula between breach diameter,explosive quantity,and slab thickness is fitted. 展开更多
关键词 Reinforced polymer slab Numerical investigations Empirical prediction Damage models
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Lead spall velocity of fragments of ultra-high-performance concrete slabs under partially embedded cylindrical charge-induced explosion
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作者 Yi Fan Li Chen +2 位作者 Heng-bo Xiang Qin Fang Fang-yu Han 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第5期50-59,共10页
When an explosion occurs close to or partially within the face of a concrete structure, fragments are rapidly launched from the opposite face of the structure owing to concrete spalling, posing a significant risk to n... When an explosion occurs close to or partially within the face of a concrete structure, fragments are rapidly launched from the opposite face of the structure owing to concrete spalling, posing a significant risk to nearby personnel and equipment. To study the lead fragment velocity of ultra-high-performance concrete(UHPC), partially embedded explosion experiments were performed on UHPC slabs of limited thickness using a cylindrical trinitrotoluene charge. The launch angles and velocities of the resulting fragments were the determined using images collected by high-speed camera to document the concrete spalling and fragment launching process. The results showed that UHPC slabs without fiber reinforcement had a fragment velocity distribution of 0-118.3 m/s, which are largely identical to that for a normal-strength concrete(NSC) slab. In addition, the fragment velocity was negatively correlated to the angle between the velocity vector and vertical direction. An empirical Eq. for the lead spall velocity of UHPC and NSC slabs was then proposed based on a large volume of existing experimental data. 展开更多
关键词 Ultra-high-performance concrete Reinforced concrete slabs Explosion Fragment velocity Blast resistance
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Blast resistance of air-backed RC slab against underwater contact explosion
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作者 Guang-dong Yang Yong Fan +3 位作者 Gao-hui Wang Xian-ze Cui Zhen-dong Leng Wen-bo Lu 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第10期236-250,共15页
Reinforced concrete(RC)structures are common in engineering,and usually exposed to air or water,may be subjected to various blast scenarios.This paper aims to investigate the blast resistance of an airbacked RC slab a... Reinforced concrete(RC)structures are common in engineering,and usually exposed to air or water,may be subjected to various blast scenarios.This paper aims to investigate the blast resistance of an airbacked RC slab against underwater contact explosions(UWCEs).A detailed numerical model based on CLE method considering explosive,water,air,and RC slab is developed to examine the structural behavior of the air-backed RC slab due to UWCEs.At first,the reliability of the numerical method is validated by comparing the numerical results of an UWCE test with experimental data.Then,the difference in dynamic behavior of air-backed and water-backed RC slabs due to UWCEs is explored with the calibrated model.The results indicate that the blast response of the air-backed slab induced by UWCE is fiercer than that of water-backed slab with equal charge mass.In addition,parametric studies are also conducted to explore the effects of the charge mass,standoff distance,reinforcement spacing,concrete compression strength,and boundary condition on the blast performance of the air-backed RC slab. 展开更多
关键词 Air-backed RC slab Underwater contact explosion Dynamic behavior Parametric study Numerical simulation
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Influences of cement asphalt emulsified mortar construction on track slab geometry status
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作者 Tao Wang Shaoliang Wu +5 位作者 Hengqiong Jia Zhao Wei Haiyan Li Piyan Shao Shanqing Peng Yi Shi 《Railway Sciences》 2023年第4期447-458,共12页
Purpose–The construction of cement asphalt(CA)emulsified mortar can obviously disturb the slab status after the fine adjustment.To decrease or eliminate the influence of CA mortar grouting on track slab geometry stat... Purpose–The construction of cement asphalt(CA)emulsified mortar can obviously disturb the slab status after the fine adjustment.To decrease or eliminate the influence of CA mortar grouting on track slab geometry status,the effects of grouting funnel,slab pressing method,mortar expansion ratio,seepage ratio and grouting area on China Railway Track System Type(CRTS I)track slab geometry status were discussed in this paper.Design/methodology/approach–Combined with engineering practice,this paper studied the expansion law of filling layer mortar,the liquid level height of the filling funnel,the pressure plate device and the amount of exudation water and systematically analyzed the influence of filling layer mortar construction on the state of track slab.Relevant precautions and countermeasures were put forward.Findings–The results showed that the track slab floating values of four corners were different with the CA mortar grouting and the track slab corner near CA mortar grouting hole had the maximum floating values.The anti-floating effect of“7”shaped slab pressing device was more efficient than fixed-joint angle iron,and the slab floating value could be further decreased by increasing the amount of“7”shaped slab pressing devices.After CA mortar grouting,the track slab floating pattern had a close correlation with the expansion rate and water seepage rate of CA mortar over time and the expansion and water seepage rate of the mortar were faster when the temperature was high.Furthermore,the use of strip CA mortar filling under the rail bearing platform on bothsides could effectively reduce the float under the track slab,and it could also save mortar consumption and reduce costs.Originality/value–This study plays an important role in controlling the floating values,CA mortar dosage and the building cost of projects by grouting CA mortar at two flanks of filling space.The research results have guiding significance for the design and construction of China’s CRTS I,CRTS II and CRTS III track slab. 展开更多
关键词 Ballastless track Track slab CA mortar Geometry status
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基于预测校正算法的Spike and Slab Lasso逻辑回归模型
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作者 齐琪 张齐 《应用数学进展》 2023年第1期292-307,共16页
尽管Spike and Slab方法广泛应用于贝叶斯变量选择,但其惩罚似然估计的潜力在很大程度上被忽视了。通过在贝叶斯模态中引入惩罚化似然观点,本文提出了新的Spike and Slab Lasso逻辑回归模型,将两个拉普拉斯密度的混合先验置于单个坐标上... 尽管Spike and Slab方法广泛应用于贝叶斯变量选择,但其惩罚似然估计的潜力在很大程度上被忽视了。通过在贝叶斯模态中引入惩罚化似然观点,本文提出了新的Spike and Slab Lasso逻辑回归模型,将两个拉普拉斯密度的混合先验置于单个坐标上,可以自适应地收缩系数,即弱收缩重要预测量,强收缩不相关预测量,从而可以得到准确的估计和预测。同时,我们使用了预测–校正算法来求解Spike and Slab Lasso逻辑回归模型,并将该算法扩展到不可分离惩罚的情况。该算法利用凸优化的预测校正算法,沿着整个正则化路径有效的计算解,方便了模型选择,避免了正则化参数值不同时的独立优化。最后,模拟学习和实证结果表明本文所提模型比Lasso逻辑回归模型具有更优的性能。 展开更多
关键词 Spike and slab Lasso 逻辑回归 惩罚似然 预测校正算法 贝叶斯先验
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Design and Construction Technology of Prefabricated Reinforced Concrete Slab Culverts
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作者 Qiang Yang 《Journal of World Architecture》 2023年第5期52-59,共8页
Compared with traditional cast-in-situ concrete slab culverts,prefabricated reinforced concrete slab culverts can be produced more quickly and has strong quality controllability,strong earthquake resistance,and repeat... Compared with traditional cast-in-situ concrete slab culverts,prefabricated reinforced concrete slab culverts can be produced more quickly and has strong quality controllability,strong earthquake resistance,and repeatability.They will be the primary production method of slab culverts in the future.This article offers a comprehensive review of the design and construction technology associated with prefabricated reinforced concrete slab culverts.The objective is to provide a valuable reference for related enterprises,enhance the quality of design and construction in precast pile configuration,and,in turn,contribute to the advancement of construction projects within our country. 展开更多
关键词 slab culvert Prefabricated reinforced concrete Design points Construction technology
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