Statistical Methodology Commons^™

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 …

Simulation Study On Confidence Interval Estimation For Standard Deviation With Non-Normal Distributions, Theophilus Oppong Kyeremeh

Electronic Theses and Dissertations

This study explores innovative approaches to constructing confidence intervals for the population standard deviation, σ, in non-normal data scenarios. While the sample standard deviation, s, is widely used, its reliability is compromised when dealing with skewed or heavy-tailed distributions and exhibits sensitivity to outliers. Our research addresses these limitations by investigating alternative estimation methods that offer greater robustness and accuracy.

A Uniformly Most Powerful Test For The Mean Of A Beta Distribution, Richard Ntiamoah Kyei

Electronic Theses and Dissertations

The beta distribution is used in numerous real-world applications, including areas such as manufacturing (quality control) and analyzing patient outcomes in health care. It also plays a key role in statistical theory, including multivariate analysis of variance (MANOVA) and Bayesian statistics. It is a flexible distribution that can account for many different characteristics of real data. To our surprise, there has been very little work or discussion on performing statistical hypothesis testing for the mean when it is reasonable to assume that the population is beta distributed. Many analysts conduct traditional analyses using a t-test or nonparametric approach, try transformations, …

Forecasting Commercial Vehicle Miles Traveled (Vmt) In Urban California Areas, Steve Chung, Jaymin Kwon, Yushin Ahn

Mineta Transportation Institute

This study investigates commercial truck vehicle miles traveled (VMT) across six diverse California counties from 2000 to 2020. The counties—Imperial, Los Angeles, Riverside, San Bernardino, San Diego, and San Francisco—represent a broad spectrum of California’s demographics, economies, and landscapes. Using a rich dataset spanning demographics, economics, and pollution variables, we aim to understand the factors influencing commercial VMT. We first visually represent the geographic distribution of the counties, highlighting their unique characteristics. Linear regression models, particularly the least absolute shrinkage and selection operator (LASSO) and elastic net regressions are employed to identify key predictors of total commercial VMT. LASSO regression …

Bayesian Approaches In Multi-State Markov Models And High Dimensional Time-To-Event Data., Yuchen Han

Electronic Theses and Dissertations

This dissertation consists of two projects. The first one involves nonparametric methods on Continuous Time Markov Chains (CTMCs). The second one is centered around Bayesian shrinkage models for detecting prognostic and predictive biomarkers in high-dimensional clinical data. Both these projects build on methods from across the frequentist and Bayesian paradigm to offer novel solutions. In the first project, we aim to model the nonlinear effects of continuous variables within multistate framework in a non-parametrically by appealing to the rich mathematical framework of Reproducing Kernel Hilbert Spaces (RKHS). Then we adapted the classical Representer Theorem to penalized (squared norm) log-likelihood which …

Experimental Study On Reinforced Geogrid Of Construction And Demolition Wastes Based On Dic Technology, Tan Peng, Li Hai, Li Xiangping, Gu Fan, Zhang Junhui

Journal of China & Foreign Highway

In order to control differential settlement caused by new and old subgrade connections after expressway reconstruction and expansion，this paper proposed a layered treatment structure for the loose steps of the old road with high water content.A layer of construction and demolition waste was laid on the step surface of the old road to wrap the geogrid.The treatment effect was compared with that of sand wrapping and lime mixing，and the digital speckle correlation （DIC） was used to observe the reinforced influence zone，so as to determine the thickness of different layers of the subgrade wrapped by construction and demolition wastes.The particle rotation …

Experimental Study On Effect Of Temperature On Bound Water Adsorption And Deformation Of High Liquid Limit Soil, Zi Yinhui, Shen Xuning, Zhang Hao, Zhang Rui, Li Lu

Journal of China & Foreign Highway

In order to study the effect of temperature change on the bound water content adsorbed by high liquid limit clay and the deformation law of high liquid limit clay embankment，the high liquid limit clay in Hainan Province was selected as the primary research object and compared with the low liquid limit sand in Hunan Province.The effect of temperature on the bound water content adsorbed by high liquid limit clay was explored through a nuclear magnetic resonance test.In addition，the effect of temperature on the deformation of high liquid limit clay embankments was analyzed through the consolidation test with a temperature-controlled consolidometer.The …

Stability Analysis Of High And Steep Bank Slope Of Jinqi Bridge On Wudang‑Changshun Expressway, Wang Hao

Journal of China & Foreign Highway

Jinqi Bridge on the Wudang-Changshun Expressway in Guizhou Province crosses the Maotiao River，and the poor geological conditions such as dangerous rock mass and collapse accumulation body on the bank slope of the river are relatively developed，which seriously affects the site selection and safety of the bridge.In order to study the stability of the high and steep bank slope of the bridge，the paper explored the main poor geological conditions in the bridge site through a comprehensive air-ground investigation.By means of numerical analysis，InSAR，and other technologies，the movement range of dangerous rock mass on the bank slope was quantitatively evaluated.The stability and deformation mode …

Shear Creep Characteristics And Slope Deformation Mechanism Of Siliceous Slate, Li Jian, Yan Liangyu, Yu Kaibing, Li Ming, Yan Tingzhou, Zhao Jia

Journal of China & Foreign Highway

To study the time-dependent creep effect of siliceous slate and the deformation and failure evolution law of high slope，in this paper，the shear creep test of indoor rock mass was carried out to plot the shear creep duration curves of siliceous slate under different normal stresses，the shear displacement-time curve，and the creep rate-time curve under different normal loads and shear loads.The average creep rate and shear load variation of siliceous slate were studied，and the long-term shear strength parameters of siliceous slate were determined by the steady-state creep rate method.The results show that in the creep test，the sensitivity of cohesion is significantly greater …

Working Performance Of Rigid Airfield Runway Considering Influence Of Cavity Depth, Dai Xuan, Li Zhao, Cai Jing, Li Yue, Liu Guoguang, Qi Lin

Journal of China & Foreign Highway

In order to analyze the influence of cavity depth on runway safety，a numerical simulation was carried out using the finite difference method.A total of 208 sets of different working conditions were designed by taking into account factors such as different aircraft types，runway dimensions，and cavity depth and area.Based on the runway life model considering the exponential decay of the structural condition，an analytical method was proposed to evaluate the impact of the cavity on the runway life.The results show that the bending and stress of the runway increase gradually with the increase in the cavity depth，but the growth rate is getting slower …

Intelligent Compaction Of Asphalt Pavement And Its Key Influencing Factors, Zhu Huifang, Wang Liang

Journal of China & Foreign Highway

Intelligent compaction，as a new type of road construction quality monitoring and management technology，has been widely used in the compaction process of asphalt pavement.However，due to the lack of understanding of the compaction process and the interaction mechanism between asphalt mixture particles，the problems of over-compaction and non-uniformity of compaction often occur in the actual construction，which seriously affects the quality of road construction and service performance.In this study，through the combination of the engineering field and indoor tests，the variation characteristics of asphalt mixture compaction with the number of compaction were analyzed by using the semi-variance function of the geostatistical model，and the effect of temperature …

Properties And Mechanism Of Reclaimed Asphalt Based On Sbs Structure Repair, Feng Xinjun, Yang Hongyang, Xiao Honghai, Zhu Ziqiang

Journal of China & Foreign Highway

At present，the common asphalt regenerant is used for treating the aged styrene-butadiene-styrene （SBS） modified asphalt in China，which fails to repair the SBS cross-networking structure，resulting in the poor regeneration effect of the aged SBS modified asphalt.In this study，a new reactive regenerator containing a structural repair agent，extractive oil，plasticizer，solubilizer，and a small amount of SBS was used to regenerate the aged SBS modified asphalt.The conventional properties and rheological properties of reclaimed SBS modified asphalt were studied by three index tests，Brookfield viscosity test，dynamic shear rheological test，and low temperature bending rheological test.Then，a fluorescence microscope and infrared spectrometer were used to study the regeneration mechanism of the …

Influence Of Lateral Constraint Conditions And Compactness On Compression Characteristics Of Compacted Loess In Northern Shaanxi, Chang Yinghong, Zhao Jinpeng, Zhang Xiaozhou, Yang Hao, Li Zhe, Shao Dengfeng, Liu Lulu

Journal of China & Foreign Highway

In recent years，with the rapid development of road engineering construction，subgrade settlement caused by vertical compression of compacted loess has become increasingly serious.The previous research on the deformation of compacted loess mostly focuses on moisture content，porosity，saturation，and other aspects，ignoring the influence of lateral constraint conditions and different compaction on compacted loess.To address these issues，based on the reconstruction and expansion project of G 307 road in northern Shaanxi，this paper selected compacted soil samples of subgrade on site to carry out indoor compression tests.By applying different lateral constraint conditions，the stress-strain curves of compacted loess subjected to vertical multistage load under different compactness and confining …

Effect Of Aging Temperature On Properties Of Sealant Under Field Construction Conditions, Liu Hanchao, Teng Xinhua, Zhang Jingyan, Zhang Kaihua, Lin Hui

Journal of China & Foreign Highway

In order to study the influence of short-term aging temperature on the properties of sealant,a sealant was prepared,and field construction conditions were simulated.The properties of the sealant before and after short-term aging at 180‒220 ℃ were tested.The viscoelastic properties,physicochemical properties,and microstructures of the sealant were studied,and the mechanism of property changes was discussed.The results show that the cone penetration and flow value of the aged sealant decrease,while the softening point and elastic recovery rate increase.Aging at high temperature (>180 ℃) for a short time and low temperature (160 ℃) for a long time will cause obvious property changes.The tensile …

Experimental Study On Capillary Water‑Holding Characteristics Of Loess Backfill In Ecological Ditches, Nan Yalin, Zhang Xiaoyu, Chen Hong, An Peng, Liu Kui, Camara Ibrahima Kalil

Journal of China & Foreign Highway

The municipal ecological ditches have the basic functions of accumulating water for infiltration in the rainy season and conserving moisture in the dry season.However，the design of loess backfill in ecological ditches is based on no evidence，which often leads to landscape vegetation drowning in the rainy season or dying in the dry season.For this reason，a study was carried out by remoulding loess with a small-size capillary water rise height test，a large-size water-holding characteristic model test，and an unsaturated numerical analysis.The results show that the final capillary water rise height of the soil column can reach 100 cm when the dry density is …

Rotating Wheel Tracking Tester And Torsional Resistance Of Asphalt Mixtures, Yao Hongru, Wang Qiang, Lu Guangyan, Zhou Xiaolong

Journal of China & Foreign Highway

Asphalt pavement is prone to pla stic deformation and aggregate raveling when it is in torsion.At present，there is no standard test method and equipment to evaluate the torsional resistance of asphalt mixtures.In order to study the effective evaluation method for the torsional shear resistance of asphalt mixtures，this paper introduced the structures and working principles of three kinds of equipment developed in Japan.The torsional resistance of five typical asphalt mixtures was evaluated by rotating wheel tracking tests，and factors affecting the torsional resistance of asphalt mixtures were analyzed.The results show that the types of structures and binders of asphalt mixtures have an …

Performance Of Composite Modified Permeable Concrete With Nano‑Silicon And Polypropylene Fiber, Liu Benli, Zhang Peng, Shan Jingsong, Zhao Haijian, Su Benjun, Li Chao

Journal of China & Foreign Highway

In order to improve the comprehensive performance of permeable concrete，nano-silicon and polypropylene fiber were added to permeable concrete to study the performance of the composite modified permeable concrete.Firstly，the influence of single-doped nano-silicon on the performance of cement paste and permeable concrete was studied，and the content of nano-silicon and the optimal water-to-binder ratio were determined.On this basis，different proportions of polypropylene fiber were mixed，and the reasonable content of polypropylene fiber was determined.The results show that nano-silicon improves the porosity of permeable concrete and increases the optimal water-to-binder ratio.When the content of nano-silicon is 0.5%，and the water-to-binder ratio is 0.32，the compressive strength of …

Research On Performance Of Coal Gangue Concrete, Wang Jiliang, Ma Wenhui, Xu Weidong, Lyu Zhigang

Journal of China & Foreign Highway

Coal gangue is an industrial solid waste produced in the process of raw coal mining.It has a large stock and a relatively low utilization rate.Using coal gangue as concrete aggregate can not only solve the environmental pollution caused by coal gangue storage but also make up for the shortage of natural sand and gravel resources，which opens up an effective way for the large-scale utilization of coal gangue.According to the application characteristics of coal gangue as concrete aggregate，the chemical component，mineral composition，and physical properties of coal gangue were systematically analyzed.The influence of coal gangue as aggregate on the working performance，mechanical properties，volume stability，and …

Oxygen Diffusion Behavior In Asphalt Film Based On Molecular Dynamics Simulation, Zhang Yu, Li Zheng, Fang Long, Han Bo, Wang Weicheng, Mao Zigen, Liu Qi, Yu Bin

Journal of China & Foreign Highway

Asphalt aging is one of the most important concerns during the use of asphalt pavement.However，asphalt usually exists in the form of a film in the mixture.Oxygen diffusion is an important factor affecting asphalt aging.To investigate the oxygen diffusion behavior in asphalt film under different working conditions，an oxygen-asphalt-aggregate （OAA） model was developed in this study to simulate the state of the asphalt film on the aggregate surface under real conditions.Oxygen diffusion and asphalt component migration in the OAA model were investigated under different conditions of time，temperature，oxygen concentration，and aggregate type.The influence of each factor on the molecular behavior of the model was …