Statistical Methodology Commons^™

Structural Repair And Performance Evaluation Of Aged Sbs Modified Asphalt, Xu Guang, Li Qishi, Kuang Huaping, Zhang Henglong, Zhou Ruibo, Chen Yanmei

Journal of China & Foreign Highway

To rejuvenate the excellent performance of aged styrene-butadiene-styrene （SBS） modified asphalt，colza oil bio-asphalt （COA） and polymethylene polyphenyl isocyanate （PAPI） were used in this study for adjusting the asphalt components and repairing SBS molecular structure，respectively.The above-mentioned dual regeneration mechanism was verified by comparing the effects of different rejuvenation components on the physical and rheological properties，as well as the molecular weight distribution of short-term aged SBS modified asphalt.Moreover，according to the change law of rheological properties of unaged base asphalt and SBS modified asphalt under the effect of dual regeneration agent，the influence of the regeneration agent on the phase angle platform area was …

Vessel Collision Force And Anti‑Collision Performance Of Long‑Span Beam‑Arch Composite Rigid Frame Bridge, Zhang Wenming, Wang Zhiwei, Lai Yaping

Journal of China & Foreign Highway

Beam-arch composite rigid frame bridge is a new bridge type，and it has few vessel collision studies.By taking the Lijia Jialing River Bridge as the engineering background，the standard value of vessel collision force and anti-collision performance of the long-span beam-arch composite rigid frame bridge were studied.After determining the representative vessel type and vessel collision calculation conditions，the vessel-bridge collision processes of the single-pier models under various calculation scenarios were simulated by using ANSYS/LS-DYNA nonlinear finite element transient dynamic software.The simulation results of collision forces were compared with the results of several empirical formulas.Finally，the full bridge model and the ultimate bearing capacity of …

Installation And Connection Mode Of Stiffening Beam Segment Of Steel Truss Suspension Bridge, Chen Changsong, Wu Junjie

Journal of China & Foreign Highway

During the construction of long-span steel truss suspension bridges，the main girder can be connected in segment-by-segment articulated connection method and rigid-articulated connection combination method.Taking a Yangtze River Highway Bridge in Hubei Province as an example，this paper established the plane calculation model of the full bridge using the Bridge Design and Construction Monitoring System BDCMS to simulate the above two connection methods of the main girder in construction.From the comprehensive analysis of chord member internal forces and line shape of the stiffening beam，this paper finds that the rigid-articulated connection combination method is more appropriate in the construction.In addition，this paper researched the …

Seismic Responses Of Cable‑Sta Yed Bridge Considering Ponding Effect Under Near‑Fa Ult Ground Motions, Lyu Long, Yu Deen, Yuan Yuhang, Yang Huaiyu

Journal of China & Foreign Highway

To study the influence of the pon ding e ffect on seismic responses of the cable-stayed bridge under near-fault ground motions，taking a double-tower cable-stayed bridge as the engineering background，this paper analyzed the ponding response of the main bridge and the main beam of the approach bridge of the cable-stayed bridge under near-fault ground motions and the influence of the ponding response on the structural seismic response.Besides，the influence of viscous dampers and elastic cables on the ponding effect of the cable-stayed bridge under near-fault ground motions was studied，which was compared with the seismic response of the cable-stayed bridge under far-fault ground …

Multi‑Dimensional And Multi‑Point Random Seismic Response Analysis Of Long‑Span Cable‑Stayed Bridges At Different Sites, Shi Yi, Lu Lu, Fan Shuli, Shen Meng, Zuo Chunyuan, Sun Xinguo, Cao Feifei

Journal of China & Foreign Highway

To study the random seismic response of long-span cable-stayed bridges at different sites，the site transfer function was used to evaluate the influence of different site conditions on ground motion propagation.By considering the traveling wave effect and the coherence effect，the multi-point power spectrum under different site conditions was generated.By using the pseudo excitation method for solving the absolute displacement，the seismic responses of cable-stayed bridges under uniform excitation and multi-dimensional and multi-point excitation at different sites were compared.A long-span cable-stayed bridge was selected as an example，and Ansys finite element software was used to analyze the random seismic response of the bridge.By considering …

Rigid Domain Optimization Of Steel Truss Joint With Reference To Multi‑Scale Model, Liu Gaocheng, Liu Jian, Dong Chuangwen, Li Chuanxi

Journal of China & Foreign Highway

The rigidity enhancement effect of the integral gusset plate is often simulated in the calculation of an integral nodal steel truss bridge by using a beam element with a rigid arm to improve the calculation accuracy.By taking Zhongshan Lianshwan Bridge as the engineering background，an optimization method based on a multi-scale truss model for nodal rigid domain simulation was proposed and verified.Five consecutive standard sections were selected as the study objects，and the beam element model with rigid arm and the multi-scale model of gusset plate substructure were established by using Ansys.The same boundary and loading conditions were applied.The deflection of the …

Impact Resistance Of Ecc Pipe Piles Based On Ls‑Dyna, Zeng Qingyou, Ye Chenfeng, Liu Junjun, Feng Kai, Cheng Peiyuan, Chen Weihong

Journal of China & Foreign Highway

To study the impact resistance of Engineering Cementitious Composite （ECC） pipe piles，this paper used ANSYS/LS-DYNA to simulate the impact of a vertical drop hammer on the pipe piles.The HJC constitutive model of ECC was established based on key parameters obtained from static tension and compression tests and dynamic compression tests.The correctness of the finite element model was verified by split Hopkinson Pressure Bar （SHPB） tests.The parametric analysis conducted on the pipe pile models compounded with different hammer mass and impact velocity yielded dynamic responses including the displacement，time-history curve of energy，and effective plastic strain diagrams of the pipe piles under various …

Comparative Study Of Different Ventilation Methods During Tunnel Construction, Yue Kun, Bao Xiaohua, Ao Xiang, Liu Kuan, Wu Han, Li Tao, Shen Jun

Journal of China & Foreign Highway

The continuous improvement of tunnel construction technology brings a rapid increase in the speed and mileage of tunnel excavation，during which ventilation is a main problem affecting construction efficiency and safety.Taking the Zhuhai Xingye Express （West Line ） tunnel project as an example，this paper studied the influences of forced ventilation，exhaust ventilation，and hybrid ventilation on the dilution and discharge of harmful gas CO near the tunnel face and the wind speed in the tunnel.The results show that hybrid ventilation performs better in CO dilution，while exhaust ventilation has higher CO emission efficiency with a lower wind speed near the working face.Therefore，although forced ventilation …

Stability Of Excavation Face Of Double‑Mode Shield In Earth Pressure Mode Crossing Fault Zone Of Pearl River, Tong Bin, Zhang Bin, Zhu Hanbiao, Wang Shuying

Journal of China & Foreign Highway

In view of the stability of the excavation face of the double-mode shield crossing the fault zone of the Pearl River，the project of the section from Hongshengsha Station to Yufengwei Station of the second phase of Guangzhou Metro Line Seven was studied.Through numerical simulations conducted to analyze the whole area and the local high-risk area of the shield crossing the fault zone of the Pearl River，this paper explored the construction risk of the shield crossing process.Besides，this paper analyzed the influence of different support stresses and grouting pressures on the stability of the excavation face and ground deformation，and finally，the tunneling parameters …

Development Trend On Raw Materials Market Of Ready‑Mixed Concrete Under Green Construction, Ding Hu, Ding Qingjun, Lin Haojun, Zhang Zhen

Journal of China & Foreign Highway

In the face of resource depletion，high energy consumption in production，high carbon emissions，and serious pollution brought by traditional pumpcrete raw materials，a variety of new raw materials have been gradually developed and promoted to conform with the green construction promoted by China ’s civil engineering industry，witnessing a stable increase in quality，output，and social recognition.High-quality natural river sand and pebbles are in short supply at the origin，and they can be explored in old silted river channels.Gravel and manufactured sand produced using large particle size natural pebbles，limestone，construction waste，and others as raw materials will become new substitutes.In the transformation and upgrading of production enterprises which tend …

Review Of Snow And Ice Melting Techniques For Road And Bridge In Cold Regions, Tang Liyun, Shao Haitao, Tang Huaming, Qiu Peiyong, Du Xiaoqi, Zhang Lei, Peng Hui

Journal of China & Foreign Highway

Snow and ice melting of road and bridge surfaces is crucial for traffic safety，but current research on snow and ice melting techniques mainly focuses on engineering effects and technical evaluation，without the analysis and elaboration from the perspective of their mechanisms.To this end，based on the different mechanisms，this study divided snow and ice melting techniques into three types and summarized them：passive deicing，active deicing，and energy utilization deicing.This study systematically evaluated the advantages and disadvantages of traditional deicing methods such as deicing agents and mechanical deicing，analyzed two active deicing techniques，namely inhibitive freezing pavement and phase change material pavement，discussed the environmental-friendly method for road deicing …

Post‑Evaluation Method For Decision‑Making And Implementation Of Highway Maintenance Projects Based On Ahp‑Dematel, Yu Wei, Yang Na, Li Jue

Journal of China & Foreign Highway

Addressing the current lack of post-evaluation management systems related to highways，particularly highway maintenance，this paper proposed a post-evaluation method for the decision-making and implementation of highway maintenance projects based on the combination of analytic hierarchy process （AHP） and decision-making trial and evaluation laboratory （DEMATEL ）.After building a post-evaluation model for the decision-making and implementation of highway maintenance projects and designing the evaluation process，this paper calculated key factors influencing the post-evaluation of the decision-making and implementation of highway maintenance projects and their respective comprehensive weights.The research results indicate that decision-making can possess higher accuracy and efficiency under the above calculation method，providing a …

Statistical Downscaling Of Climate Datasets With Deep Generative Model And Bayesian Inference, Guiye Li, Guofeng Cao

I-GUIDE Forum

Facing the challenges of global climate change, precise and high spatial resolution climate data are crucial and in pressing need for scientific research and analysis. However, most existing datasets are only available with very coarse spatial resolution and demand large-scale resolution enhancement. Meanwhile, climate datasets own much more intricate textures than natural images. Statistical downscaling or super-resolution (SR) with the deep-learning-based generative model might be a promising approach to address these challenges. It is worth noting that a learned Bayesian reconstruction with generative models (L-BRGM) method was proposed recently. The proposed Bayesian deep learning framework employs a single pre-trained generative …

Assessing The Impact Of Femur Morphological Variations On Pediatric Hip Joint Biomechanics Using Statistical Shape Modeling, Tamara Chambers

Doctoral Dissertations and Master's Theses

This dissertation aimed to (1) quantify morphological variations in the pediatric hip joint and (2) evaluate the sensitivity of an infant musculoskeletal model (MSM) to these variations, considering hip joint center estimation errors. A shape statistical model (SSM) of decedent infant femurs from the Ortolani collection was created using ShapeWorks, capturing key morphological features, such as variations in the femoral neck-shaft and anteversion angles. Seven synthetic femurs were generated from the SSM to create SSM-informed MSMs, which were systematically evaluated through kinematics and kinetics analyses in OpenSim. Incorporating the SSM led to slight changes in the pediatric MSMs’ kinematics but …

Human Capital At Home: Evidence From A Randomized Evaluation In The Philippines, Noam Angrist, Sarah Kabay, Dean S. Karlan, Lincoln Lau, Kevin M. Wong

Education Division Scholarship

Children spend most of their time at home in their early years, yet efforts to promote human capital at home in many low- and middle-income settings remain limited. We conduct a randomized controlled trial to evaluate an intervention which encourages parents and caregivers to foster human capital accumulation among their children between ages 3 and 5, with a focus on math and phonics skills. Children gain 0.52 and 0.51 standard deviations relative to the control group on math and phonics tests, respectively (p<0.001). A year later effects persist, but math gains dissipate to 0.15 (p=0.06) and phonics to 0.13 (p=0.12). Effects appear to be mediated largely through instructional support by parents and not other parent investment mechanisms, such as more positive parent-child interactions or additional time spent on education at home beyond the intervention. Our results show that parents can be effective conduits of educational instruction even in low-resource settings.

Improvement And Evaluation Of Multiple Imputation By Heckman's One-Step Mle For Binary Mnar Outcomes And Various Types Of Mar Covariates, Xin W. Shore

Mathematics & Statistics ETDs

Missing data is inevitable in clinical epidemiology. It becomes one of the major challenges in the analyses and can potentially undermine the validity of results and conclusions. Although methods for handling missing data with mechanisms of missing completely at random (MCAR) or missing at random (MAR) have been widely researched, methods adapted for the missing not at random (MNAR) mechanism are less studied. Galimard et al. (2018) have derived a method to use multiple imputation by Heckman's One-Step ML Estimation for binary MNAR outcome and continuous MAR covariates (MIHEml). This dissertation focuses on updating MIHEml in terms of …

Investigating Mixed Effects Random Forest Models In Predicting Satisfaction With Online Learning In Higher Education, Jiaqi (Jackie) Shi

Electronic Theses and Dissertations

One of the many impacts of the COVID-19 pandemic has been the increasing prevalence and accessibility of online education. This trend has also introduced challenges for students, instructors, and institutions. This study examines factors affecting online course satisfaction, focusing on individual, instructor, and institutional level characteristics with clustered, separated train and test datasets across two terms. This study compares Hierarchical Linear Model (HLM), Non-clustered and Clustered Random Forest (RF & MERF) models to understand these impacts. This intention is to provide a comprehensive framework comparing traditional HLM with the latest developed MERF models while delving into the effectiveness of RF …

The Naked Truth Of My Voice: Surveying The Soul Of An Aspiring Educator From Dusk To Dawn: An Arts-Based Auto-Criticism Inquiry, Siddharth Maan

Electronic Theses and Dissertations

This dissertation is based on auto-criticism, a new qualitative inquiry that combines educational criticism and arts-based research. It focuses on my own experiences as an aspiring educator who struggles with stuttering and public speaking anxiety. The study aims to describe, interpret, evaluate, and thematize my experiences of dealing with public speaking anxiety and stuttering before, during, and after classroom teaching. In addition, this dissertation highlights the potential contributions of auto-criticism as a methodology to qualitative research and higher education. I utilized journaling to document data. Photos and music were also used to enhance the understanding of my lived experiences and …

Bayesian Variational Inference In Keyword Identification And Multiple Instance Classification, Yaofang Hu

Statistical Science Theses and Dissertations

This dissertation investigates (1) Variational Bayesian Semi-supervised Keyword Extraction and (2) Variational Bayesian Multimodal Multiple Instance Classification.

The expansion of textual data, stemming from various sources such as online product reviews and scholarly publications on scientific discoveries, has created a demand for the extraction of succinct yet comprehensive information. As a result, in recent years, efforts have been spent in developing novel methodologies for keyword extraction. Although many methods have been proposed to automatically extract keywords in the contexts of both unsupervised and fully supervised learning, how to effectively use partially observed keywords, such as author-specified keywords, remains an under-explored …

Assessing Gtfs Accuracy, Gregory L. Newmark

Mineta Transportation Institute

The promised benefits of the General Transit Feed Specification (GTFS) Schedule and Realtime standards are dependent on the underlying quality of the data. Despite this fundamental reliance, there has been relatively little research on techniques and strategies to assess GTFS accuracy. The need for such assessment is growing as federal and state governments increasingly require transit agencies to make these data available to the public. This research fills this gap by presenting a suite of methods and metrics to assess the temporal accuracy of GTFS Realtime and the spatial accuracy of GTFS Schedule feeds. The temporal assessment demonstrates an approach …