Diatomaceous soils are comprised of the silica frustules of diatom microalgae that are present in marine and lacustrine environments throughout the world.Owing to their unique origin,diatomaceous soils are typically c...Diatomaceous soils are comprised of the silica frustules of diatom microalgae that are present in marine and lacustrine environments throughout the world.Owing to their unique origin,diatomaceous soils are typically characterized by high intraparticle porosity,complex particle shapes,and uniform mineralogy,causing them to exhibit atypical physical and engineering behaviors.A substantial deposit of diatomaceous silt was observed during site exploration for construction of the Buck Creek Bridge on OR140 near Klamath Falls,OR,USA.A comprehensive laboratory and in situ testing program indicated that the diatomaceous soil possessed“non-textbook”engineering properties.Specifically,tested samples had high liquid limits(≈100%-140%)with natural water contents at or near the liquid limit.Geologically,the soil is expected to be normally consolidated,yet high apparent overconsolidation ratios(OCR)(≈15-40)were observed both in oedometric consolidation tests and through cone penetration test(CPT)correlations.Standard penetration test(SPT)results show a corrected standard penetration resistance consistent with a medium-dense sand(i.e.(N1)_(60)≈25).CPT results include corrected tip resistances(qt)of approximately 7-10 MPa and excess pore pressures(u_(2))of up to 4 MPa.In CPT dissipation tests,pore water pressures(PWPs)returned to hydrostatic pressure in less than 1 h.In this work,we synthesize these seemingly disparate material properties in an attempt to infer appropriate engineering properties for the diatomaceous deposit at the Buck Creek Bridge and attempt to provide insight into the underlying reasons for the observed behavior.展开更多
Climate change is expected to have long-term impacts on drought and wildfire risks in Oregon as summers continue to become warmer and drier. This paper investigates the projected changes in drought characteristics and...Climate change is expected to have long-term impacts on drought and wildfire risks in Oregon as summers continue to become warmer and drier. This paper investigates the projected changes in drought characteristics and drought propagation in the Umatilla River Basin in northeastern Oregon for mid-century(2030–2059) and late-century(2070–2099) climate scenarios. Drought characteristics for projected climates were determined using downscaled CMIP5 climate datasets from ten climate models and Soil and Water Assessment Tool to simulate effects on hydrologic processes. Short-term(three months) drought characteristics(frequency, duration, and severity) were analyzed using four drought indices, including the Standardized Precipitation Index(SPI-3), Standardized Precipitation-Evapotranspiration Index(SPEI-3), Standardized Streamflow Index(SSI-3), and the Standardized Soil Moisture Index(SSMI-3). Results indicate that short-term meteorological droughts are projected to become more prevalent, with up to a 20% increase in the frequency of SPI-3drought events. Short-term hydrological droughts are projected to become more frequent(average increase of 11% in frequency of SSI-3 drought events), more severe, and longer in duration(average increase of 8% for short-term droughts).Similarly, short-term agricultural droughts are projected to become more frequent(average increase of 28% in frequency of SSMI-3 drought events) but slightly shorter in duration(average decrease of 4%) in the future. Historically, drought propagation time from meteorological to hydrological drought is shorter than from meteorological to agricultural drought in most sub-basins. For the projected climate scenarios, the decrease in drought propagation time will likely stress the timing and capacity of water supply in the basin for irrigation and other uses.展开更多
Cybercriminals often use fraudulent emails and fictitious email accounts to deceive individuals into disclosing confidential information,a practice known as phishing.This study utilizes three distinct methodologies,Te...Cybercriminals often use fraudulent emails and fictitious email accounts to deceive individuals into disclosing confidential information,a practice known as phishing.This study utilizes three distinct methodologies,Term Frequency-Inverse Document Frequency,Word2Vec,and Bidirectional Encoder Representations from Transform-ers,to evaluate the effectiveness of various machine learning algorithms in detecting phishing attacks.The study uses feature extraction methods to assess the performance of Logistic Regression,Decision Tree,Random Forest,and Multilayer Perceptron algorithms.The best results for each classifier using Term Frequency-Inverse Document Frequency were Multilayer Perceptron(Precision:0.98,Recall:0.98,F1-score:0.98,Accuracy:0.98).Word2Vec’s best results were Multilayer Perceptron(Precision:0.98,Recall:0.98,F1-score:0.98,Accuracy:0.98).The highest performance was achieved using the Bidirectional Encoder Representations from the Transformers model,with Precision,Recall,F1-score,and Accuracy all reaching 0.99.This study highlights how advanced pre-trained models,such as Bidirectional Encoder Representations from Transformers,can significantly enhance the accuracy and reliability of fraud detection systems.展开更多
This research investigates the intricate relationship between the number of lanes on highways and injury severities sustained by commercial motor vehicle(CMV)drivers.Many studies have addressed crash determinants,but ...This research investigates the intricate relationship between the number of lanes on highways and injury severities sustained by commercial motor vehicle(CMV)drivers.Many studies have addressed crash determinants,but the safety implications of differing numbers of lanes remain insufficiently examined,especially during the highway planning stages.Our study fills this knowledge gap by analyzing injury severity crash factors for a varied number of lane scenarios.Employing a random parameter logit modeling framework,we differentiated injury levels for 2-4 lanes and 6-10 lanes.Key factors were identified for each number of lanes,with older,loss of vehicle control,non-collision crashes,and crashes,on locations where grade or hill existed,being more perilous and increasing the risk of sustaining severe injuries on 2-lane highways.For 4-lane highways,factors such as non-Oregonian drivers,older drivers,crashes that occurred during the spring season,and crashes that occurred beyond shoulders were associated with an elevated probability of being involved in severe injury crashes.Regarding highways with 6 lanes and higher,driving too fast for conditions and driver error(drowsy,fatigued,inattentive,or reckless)increases the odds of being involved in higher levels of injury crashes.To enhance truck driver safety,we recommend the implementation of electronic stability control in CMVs,with moderated speeds on graded sections,improved curve markers,and robust public safety campaigns.展开更多
Persons with disabilities have difficulties traveling from one point to the other due to the limited options of travel modes for the first and last mile.Western Michigan University tested using an autonomous shuttle o...Persons with disabilities have difficulties traveling from one point to the other due to the limited options of travel modes for the first and last mile.Western Michigan University tested using an autonomous shuttle on the main campus's sidewalks for persons with disabilities.This study's objectives are to understand the empathy college students without disabilities had on the need for suitable transportation services for students with disabilities and the perceived risks of the services'operation on sidewalks.The Bayesian ordered logit model and text mining analyzed 396 survey responses.The Bayesian ordered logistic regression results revealed that age,gender,and ethnicity are important factors that contribute to different opinions concerning perceived risks and sympathy brought by an autonomous shuttle operating on pedestrians'sidewalks.The text mining results revealed several patterns.While respondents who were against the operation focused on potential safety hazards and the crowdedness of the sidewalks,supporters focused on the expected improved mobility for people with disabilities.The findings from this study are expected to assist policymakers and vehicle manufacturers with pedestrian expectations and considerations related to risk and safety when sharing their walkways with the autonomous shuttle.展开更多
Pavement condition monitoring and its timely maintenance is necessary to ensure the safety and quality of the roadway infrastructure. The International Roughness Index (IRI) is a commonly used measure to quantify road...Pavement condition monitoring and its timely maintenance is necessary to ensure the safety and quality of the roadway infrastructure. The International Roughness Index (IRI) is a commonly used measure to quantify road surface roughness and is a critical input to asset management. In Indiana, the IRI statistic contributes to roughly half of the pavement quality index computation used for asset management. Most agencies inventory IRI once a year, however, pavement conditions vary much more frequently. The objective of this paper is to develop a framework using crowdsourced connected vehicle data to identify and detect temporal changes in IRI. Over 3 billion connected vehicle records in Indiana were analyzed across 30 months between 2022 and 2024 to understand the spatiotemporal variations in roughness. Annual comparisons across all major interstates in Indiana showed the miles of interstates classified as “Good” decreased from 1896 to 1661 miles between 2022 and 2024. The miles of interstate classified as “Needs Maintenance” increased from 82 to 120 miles. A detailed case study showing monthly and daily changes of estimated IRI on I-65 are presented along with supporting dashcam images. Although the crowdsourced IRI estimates are not as robust as traditional specialized pavement profilers, they can be obtained on a monthly, weekly, or even daily basis. The paper concludes by suggesting a combination of frequent crowdsourced IRI and commercially available dashcam imagery of roadway can provide an agile and responsive mechanism for agencies to implement pavement asset management programs that can complement existing annual programs.展开更多
Crushing of grains can greatly influence the strength,dilatancy,and stress-strain relationship of rockfill materials.The critical state line(CSL)in the void ratio versus mean effective stress plane was extended to the...Crushing of grains can greatly influence the strength,dilatancy,and stress-strain relationship of rockfill materials.The critical state line(CSL)in the void ratio versus mean effective stress plane was extended to the breakage critical state plane(BCSP).A state void-ratio-pressure index that incorporated the effect of grain crushing was proposed according to the BCSP.Rowe’s stress-dilatancy equation was modified by adding the breakage voidratio-pressure index,which was also incorporated into the formulations of the bounding stress ratio and plastic modulus.A BCSP-based bounding surface plasticity model was proposed to describe the state-dependent stressstrain behaviors and the evolution of grain crushing during shearing process of rockfill materials,and was shown to sufficiently capture the breakage phenomenon.展开更多
Grain crushing is commonly encountered in deep foundation engineering,high rockfill dam engineering,railway engineering,mining engineering,coastal engineering,petroleum engineering,and other geoscience application.Gra...Grain crushing is commonly encountered in deep foundation engineering,high rockfill dam engineering,railway engineering,mining engineering,coastal engineering,petroleum engineering,and other geoscience application.Grain crushing is affected by fundamental soil characteristics,such as their mineral strength,grain size and distribution,grain shape,density and specimen size,and also by external factors including stress magnitude and path,loading rate and duration,degree of saturation,temperature and geochemical environment.Crushable material becomes a series of different materials with the change in its grading during grain crushing,resulting in a decrease in strength and dilatancy and an increase in compressibility.Effects of grain crushing on strength,dilatancy,deformation and failure mechanisms have been extensively investigated through laboratory testing,discrete element method(DEM)modelling,Weibull statistics,and constitutive modelling within the framework of the extended crushing-dependent critical state theory or the energy-based theory.Eleven papers summarized in this review article for this special issue addressed the above issues in grain crushing through the advanced testing and modelling.展开更多
Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, ...Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, this work estimates local-scale vehicular emissions and concentrations near a highway traffic network, where a school zone is located in. In the case study, VISSIM traffic micro-simulation is used to estimate the source of vehicular emissions at each roadway segment. The local-scale emission sources are then used as inputs to the California line source dispersion model(CALINE4) to estimate concentrations across the study area. To justify the local-scale emissions modeling approach, the simulation experiment is conducted under various traffic conditions. Different meteorological conditions are considered for emission dispersion. The work reveals that emission concentrations are usually higher at locations closer to the congested segments, freeway ramps and major arterial intersections. Compared to the macroscopic estimation(i.e. using network-average emission factors), the results show significantly different emission patterns when the local-scale emission modeling approach is used. In particular, it is found that the macroscopic approach over-estimates emission concentrations at freeways and under-estimations are observed at arterials and local streets. The results of the study can be used to compare to the US environmental protection agency(EPA) standards or any other air quality standard to further identify health risk in a fine-grained manner.展开更多
This paper presents the results from a case study highlighting the difficulties of pile driving in diatomaceous soils.In the companion(first)paper to this article,results of an extensive laboratory and in situ testing...This paper presents the results from a case study highlighting the difficulties of pile driving in diatomaceous soils.In the companion(first)paper to this article,results of an extensive laboratory and in situ testing program were presented while the results from pile driving and further analysis of field observations were presented herein.Unexpected high pile rebound(HPR)was observed during driving of a closed-end pipe pile,with refusal occurring at a depth of less than 5 m.Subsequent open-ended piles were thus driven.Piezometer and case pile wave analysis program(CAPWAP)data were collected during driving of both closed-and open-end piles.Piezometer data indicated that negative pore water pressures(PWPs)were generated while the closed-ended pile exhibited high rebound.Results from in situ tests indicated change in material stiffness and strong dilative tendencies near the depth of refusal.A hypothesis for observed behavior was proposed that considers the soil beneath the pile as a medium with an effectively infinite bulk modulus.展开更多
Viscoelastic（VE） dampers, with their stiffness and energy dissipation capabilities, have been widely used in civil engineering for mitigating wind-induced vibration and seismic responses of structures, thus enhancin...Viscoelastic（VE） dampers, with their stiffness and energy dissipation capabilities, have been widely used in civil engineering for mitigating wind-induced vibration and seismic responses of structures, thus enhancing the comfort of residents and serviceability of equipment inside. In past relevant research, most analytical models for characterizing the mechanical behavior of VE dampers were verified by comparing their predictions with performance test results from small-scale specimens, which might not adequately or conservatively represent the actual behavior of full-scale dampers, especially with regard to the ambient temperature, temperature rise, and heat convection effects. Thus, in this study, by using a high-performance testing facility with a temperature control system, full-scale VE dampers were dynamically tested with different displacement amplitudes, excitation frequencies, and ambient temperatures. By comparing the analytical predictions with the experimental results, it is demonstrated that adopting the fractional derivative method together with considering the effects of excitation frequencies, ambient temperatures, temperature rises, softening, and hardening, can reproduce the design performance of full-scale VE dampers very well.展开更多
Although pre-Northridge earthquake steel moment resisting frame buildings have been shown to be susceptible to brittle connection failures,they still represent a large fraction of the existing steel buildings in the U...Although pre-Northridge earthquake steel moment resisting frame buildings have been shown to be susceptible to brittle connection failures,they still represent a large fraction of the existing steel buildings in the United States of America.In this study,the performance of the 3-and 9-story Los Angeles pre-Northridge SAC buildings are analyzed considering ductile and brittle beam-column connection failures,and their uncertainty.This paper contributes to understanding the influence of uncertainty associated with connections brittle fracture on building interstory deformation capacity and its impact on bias and variability of fragility functions and loss assessment.The results show that considering brittle connections leads to significantly l arger d rift demands a nd t o h igher r epair costs,particularly under intense ground shaking.New fragility curve parameters are derived that account for the effect of the uncertainty of the strength and deformation capacity of brittle connections.展开更多
Higher-order multiscale structures are proposed to predict the effective elastic properties of 3-phase particle reinforced composites by considering the probabilistic spherical particles spatial distribution,the parti...Higher-order multiscale structures are proposed to predict the effective elastic properties of 3-phase particle reinforced composites by considering the probabilistic spherical particles spatial distribution,the particle interactions,and utilizing homogenization with ensemble volume average approach.The matrix material,spherical particles with radius a1,and spherical particles with radius a2,are denoted as the 0th phase,the 1st phase,and the 2nd phase,respectively.Particularly,the two inhomogeneity phases are different particle sizes and the same elastic material properties.Improved higher-order(in ratio of spherical particle sizes to the distance between the centers of spherical particles)bounds on effective elastic properties of 3-phase particle reinforced proposed Formulation II and Formulation I derive composites.As a special case,i.e.,particle size of the 1st phase is the same as that of the 2nd phase,the proposed formulations reduce to 2-phase formulas.Our theoretical predictions demonstrate excellent agreement with selected experimental data.In addition,several numerical examples are presented to demonstrate the competence of the proposed frameworks.展开更多
Accuracy of hydrodynamic and water quality numerical models developed for a specific site is dependent on multiple model parameters and variables whose values are attained via calibration processes and/or expert knowl...Accuracy of hydrodynamic and water quality numerical models developed for a specific site is dependent on multiple model parameters and variables whose values are attained via calibration processes and/or expert knowledge. Real time variations in the actual aquatic system at a site necessitate continuous monitoring of the system so that model parameters and variables are regularly updated to reflect accurate conditions. Multiple sources of observations can help adjust the model better by providing benefits of individual monitoring technology within the model updating process. For example, remote sensing data provide a spatially dense dataset of model variables at the surface of a water body, while in-situ monitoring technologies can provide data at multiple depths and at more frequent time intervals than remote sensing technologies. This research aims to present an overview of an integrated modeling and data assimilation framework that combines three-dimensional numerical model with multiple sources of observations to simulate water column temperature in a eutrophic reservoir in central Indiana. A variational data assimilation approach is investigated for incorporating spatially continuous remote sensing temperature observations and spatially discrete in-situ observations to change initial conditions of the numerical model. The results demonstrate the challenges in improving the model performance by incorporating water temperature from multi-spectral remote sensing analysis versus in-situ measurements. For example, at a eutrophic reservoir in Central Indiana where four images of multi-spectral remote sensing data were assimilated in the numerical model, the overall error for the four images reduced from 20.9% (before assimilation) to 15.9% (best alternative after the assimilation). Additionally, best improvements in errors were observed on days closer to the starting time of model’s assimilation time window. However, when the original and updated model results for the water column temperature were compared to the in-situ measurements during the data assimilation period, the error was found to have actually increased from 1.8℃ (before assimilation) to 2.7℃ (after assimilation). Sampling depth differences between remote sensing observations and in-situ measurements, and spatial and temporal sampling of remote sensing observations are considered as possible reasons for this contrary behavior in model performance. The authors recommend that additional research is needed to further examine this behavior.展开更多
This study compares the effect of treated pineapple leaves fibres (T-PALF) with sodium hydroxide solution and untreated fibres (N-PALF) on the compressive and flexural strength of earth bricks stabilized with 3% and 5...This study compares the effect of treated pineapple leaves fibres (T-PALF) with sodium hydroxide solution and untreated fibres (N-PALF) on the compressive and flexural strength of earth bricks stabilized with 3% and 5% cement. The fibre content ranged from 0% to 5% in steps of 1% by weight. The compressive strength tests were made at 7, 14, 21 and 28 days of curing;the flexural strength test were conducted at 28th day only. The results show that the T-PALF had a higher compressive strength when comparing to the N-PALF. The highest compressive strength of the bricks was obtained at 28 days of curing. The compressive strength at 28 days of stabilized brick at 3% and 5% of cement reinforced with T-PALF were 4.01 and 4.81 MPa, respectively, while the one reinforced with N-PALF was 3.19 and 4.63 MPa, respectively. The results further show that the highest flexural strength of both stabilized bricks at 3% and 5% of cement reinforced with T-PALF and N-PALF was obtained with the bricks stabilized with 5% of cement reinforced with T-PALF. This results show that bricks stabilized with 5% cement and reinforced with 3% of treated fibres content are good for construction of load bearing walls. It was observed;a significant improvement of the reinforced blocks under flexure than under compression.展开更多
Safe water of adequate quantity, and dignified sanitation, is vital for the sustenance of a healthy and productive human population. In the recognition of this, the United Nations formulated the Sustainable Developmen...Safe water of adequate quantity, and dignified sanitation, is vital for the sustenance of a healthy and productive human population. In the recognition of this, the United Nations formulated the Sustainable Development Goal No. 6 to ensure access to safe water and sanitation by all by 2030. Actualization of this Goal requires information on the existing status of water resources and sanitation levels. Knowledge on contamination of groundwater is essential to prevent risks to human health. The objective of this study was to determine groundwater contamination in Kisumu, Kenya. A total of 275 water samples were collected from 22 sites within the informal settlements between December 2016 and December 2017. The samples were analysed for bacterial contamination and physical chemical quality. Thermal tolerant coliform bacteria enumeration was used as a proxy to bacteria contamination, and the pH, turbidity, dissolved oxygen, conductivity, salinity and temperature were used as physical chemical indicators of contamination. The results indicate that groundwater in Kisumu hosed coliform bacteria and therefore didn’t comply with contamination limits for domestic water proposed by WHO and local KEBS standards. The results further indicated that the levels of bacteriological contamination vary with water type, shallow well having the highest bacterial loads. The study concluded that there were potential risks to human health due to high content of coliform bacteria. The study attributed the contribution to pit latrines that were present in virtually all compounds. The pit latrines are located close to the water points. The study recommended the definition of minimum distance between the pit latrines and shallow wells to minimize contamination. The low income dwellers should be educated on simple ways of treating drinking water contaminated by microbial to minimize enteric infections.展开更多
This work aims at solving the problems of difficult dispersion,easy oxidation and high cost of nano carbon during application,carbon/magnesium aluminate spinel(C/MgAl_(2)O_(4))composite powders were prepared using MgC...This work aims at solving the problems of difficult dispersion,easy oxidation and high cost of nano carbon during application,carbon/magnesium aluminate spinel(C/MgAl_(2)O_(4))composite powders were prepared using MgC2O4·2H2O,MgO2,Al2O3 powder,and Al powder as raw materials by combustion synthesis.The results indicate that with the maximum MgC2O4·2H2O addition of 33.34 mass%,the prepared powder contains 1.17 mass%of carbon and carbon distributes among spinel grains.The MgAl_(2)O_(4)spinel shows both granular and rod-like morphologies.The granular MgAl_(2)O_(4)spinel is generated from mutual diffusion between MgO and Al2O3;while the rod-like MgAl_(2)O_(4)spinel is mainly formed by the vapor-solid growth mechanism from Mg vapor and Al2O3.展开更多
Many studies have been conducted by analyzing crash data that included road profile, site conditions, vehicle configurations and weights, driver behavior, etc.. However, limited studies have been conducted evaluating ...Many studies have been conducted by analyzing crash data that included road profile, site conditions, vehicle configurations and weights, driver behavior, etc.. However, limited studies have been conducted evaluating the impact of these factors on crashes and/or rollover through simulations. This is mainly due to lack of availability of verified full vehicle flexible-body models. The verification process is costly as it requires instrumentation of a heavy vehicle, scanning of road surfaces, and collection of data by running the vehicle over different road conditions, performing various maneuvering, etc. This paper presents the reverse engineering process of a class-8 truck and validation of a full flexible-body simulation model of a Wabash 53-foot trailer against the strain data recoded from proving ground testing of an instrumented truck. Simulation results show that, with the exception of the noise from the strain gage data from instrumented test run at 30 mph, there is a good agreement in periodicity and relative amplitude with the ADAMS model. A comparison of strain data from the flex-body model and the instrumented truck shows that the modeling and verification approach presented in this paper can be confidently used to validate the full flexible-body models developed for specific analyses.展开更多
This experimental research is focused on the effect of concrete made by incorporating lime treated Palm Kernel Shell (PKS) & Sugarcane Bagasse Ash (SCBA) as partial replacements of coarse aggregates and Ordinary P...This experimental research is focused on the effect of concrete made by incorporating lime treated Palm Kernel Shell (PKS) & Sugarcane Bagasse Ash (SCBA) as partial replacements of coarse aggregates and Ordinary Portland Cement (OPC) respectively. An experimental analysis for concrete grade 30 with a mix design ratio of 1:1.97:3.71 of cement:fine aggregates:coarse aggregates with a constant water to cement ratio of 0.5, was used. Physical tests such as workability on fresh concrete and water absorption on hardened concrete of each batch were carried out. Mechanical tests like compressive strength and split tensile strength were carried out on hardened concrete cubes (100 mm × 100 mm × 100 mm) and cylinders (100 mm × 200 mm) at 7 and 28 days. The experimental results obtained in this study indicate the possibility of using up 15% of lime treated PKS and 10% of SCBA for production of structural concrete.展开更多
The early asphalt pavement in our country severely reduced the road performance due to various external factors during the use process.According to incomplete statistics,there are more asphalt pavements that need to b...The early asphalt pavement in our country severely reduced the road performance due to various external factors during the use process.According to incomplete statistics,there are more asphalt pavements that need to be renovated and repaired every year in China,and the amount of construction waste such as asphalt concrete and other construction waste reaches 1,000.About ten thousand tons.If such a huge amount of construction waste is not used,it will inevitably cause great pollution to the environment.If it can be reused,not only will it be environmentally friendly and energy-saving,it will also save more than one billion yuan in costs.In view of the above problems,this article conducts related Research and Analysis on the Principle in Plant Cold Recycling for Foamed Bitumen and Mixture Performance to provide reference for future projects.展开更多
基金This work was funded by the Oregon Department of Transportation(ODOT),which is gratefully acknowledged.
文摘Diatomaceous soils are comprised of the silica frustules of diatom microalgae that are present in marine and lacustrine environments throughout the world.Owing to their unique origin,diatomaceous soils are typically characterized by high intraparticle porosity,complex particle shapes,and uniform mineralogy,causing them to exhibit atypical physical and engineering behaviors.A substantial deposit of diatomaceous silt was observed during site exploration for construction of the Buck Creek Bridge on OR140 near Klamath Falls,OR,USA.A comprehensive laboratory and in situ testing program indicated that the diatomaceous soil possessed“non-textbook”engineering properties.Specifically,tested samples had high liquid limits(≈100%-140%)with natural water contents at or near the liquid limit.Geologically,the soil is expected to be normally consolidated,yet high apparent overconsolidation ratios(OCR)(≈15-40)were observed both in oedometric consolidation tests and through cone penetration test(CPT)correlations.Standard penetration test(SPT)results show a corrected standard penetration resistance consistent with a medium-dense sand(i.e.(N1)_(60)≈25).CPT results include corrected tip resistances(qt)of approximately 7-10 MPa and excess pore pressures(u_(2))of up to 4 MPa.In CPT dissipation tests,pore water pressures(PWPs)returned to hydrostatic pressure in less than 1 h.In this work,we synthesize these seemingly disparate material properties in an attempt to infer appropriate engineering properties for the diatomaceous deposit at the Buck Creek Bridge and attempt to provide insight into the underlying reasons for the observed behavior.
基金the financial support received from the U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA), USA (Grant No.2017-67003-26057) via an interagency partnership between USDA-NIFAthe National Science Foundation (NSF) on the research program Innovations at the Nexus of Food, Energy and Water Systemsfunded by the Ministry of Education, Government of India through the Scheme for Promotion of Academic and Research Collaboration (SPARC) project grant (SPARC/2018-2019/P1080/SL)。
文摘Climate change is expected to have long-term impacts on drought and wildfire risks in Oregon as summers continue to become warmer and drier. This paper investigates the projected changes in drought characteristics and drought propagation in the Umatilla River Basin in northeastern Oregon for mid-century(2030–2059) and late-century(2070–2099) climate scenarios. Drought characteristics for projected climates were determined using downscaled CMIP5 climate datasets from ten climate models and Soil and Water Assessment Tool to simulate effects on hydrologic processes. Short-term(three months) drought characteristics(frequency, duration, and severity) were analyzed using four drought indices, including the Standardized Precipitation Index(SPI-3), Standardized Precipitation-Evapotranspiration Index(SPEI-3), Standardized Streamflow Index(SSI-3), and the Standardized Soil Moisture Index(SSMI-3). Results indicate that short-term meteorological droughts are projected to become more prevalent, with up to a 20% increase in the frequency of SPI-3drought events. Short-term hydrological droughts are projected to become more frequent(average increase of 11% in frequency of SSI-3 drought events), more severe, and longer in duration(average increase of 8% for short-term droughts).Similarly, short-term agricultural droughts are projected to become more frequent(average increase of 28% in frequency of SSMI-3 drought events) but slightly shorter in duration(average decrease of 4%) in the future. Historically, drought propagation time from meteorological to hydrological drought is shorter than from meteorological to agricultural drought in most sub-basins. For the projected climate scenarios, the decrease in drought propagation time will likely stress the timing and capacity of water supply in the basin for irrigation and other uses.
文摘Cybercriminals often use fraudulent emails and fictitious email accounts to deceive individuals into disclosing confidential information,a practice known as phishing.This study utilizes three distinct methodologies,Term Frequency-Inverse Document Frequency,Word2Vec,and Bidirectional Encoder Representations from Transform-ers,to evaluate the effectiveness of various machine learning algorithms in detecting phishing attacks.The study uses feature extraction methods to assess the performance of Logistic Regression,Decision Tree,Random Forest,and Multilayer Perceptron algorithms.The best results for each classifier using Term Frequency-Inverse Document Frequency were Multilayer Perceptron(Precision:0.98,Recall:0.98,F1-score:0.98,Accuracy:0.98).Word2Vec’s best results were Multilayer Perceptron(Precision:0.98,Recall:0.98,F1-score:0.98,Accuracy:0.98).The highest performance was achieved using the Bidirectional Encoder Representations from the Transformers model,with Precision,Recall,F1-score,and Accuracy all reaching 0.99.This study highlights how advanced pre-trained models,such as Bidirectional Encoder Representations from Transformers,can significantly enhance the accuracy and reliability of fraud detection systems.
文摘This research investigates the intricate relationship between the number of lanes on highways and injury severities sustained by commercial motor vehicle(CMV)drivers.Many studies have addressed crash determinants,but the safety implications of differing numbers of lanes remain insufficiently examined,especially during the highway planning stages.Our study fills this knowledge gap by analyzing injury severity crash factors for a varied number of lane scenarios.Employing a random parameter logit modeling framework,we differentiated injury levels for 2-4 lanes and 6-10 lanes.Key factors were identified for each number of lanes,with older,loss of vehicle control,non-collision crashes,and crashes,on locations where grade or hill existed,being more perilous and increasing the risk of sustaining severe injuries on 2-lane highways.For 4-lane highways,factors such as non-Oregonian drivers,older drivers,crashes that occurred during the spring season,and crashes that occurred beyond shoulders were associated with an elevated probability of being involved in severe injury crashes.Regarding highways with 6 lanes and higher,driving too fast for conditions and driver error(drowsy,fatigued,inattentive,or reckless)increases the odds of being involved in higher levels of injury crashes.To enhance truck driver safety,we recommend the implementation of electronic stability control in CMVs,with moderated speeds on graded sections,improved curve markers,and robust public safety campaigns.
文摘Persons with disabilities have difficulties traveling from one point to the other due to the limited options of travel modes for the first and last mile.Western Michigan University tested using an autonomous shuttle on the main campus's sidewalks for persons with disabilities.This study's objectives are to understand the empathy college students without disabilities had on the need for suitable transportation services for students with disabilities and the perceived risks of the services'operation on sidewalks.The Bayesian ordered logit model and text mining analyzed 396 survey responses.The Bayesian ordered logistic regression results revealed that age,gender,and ethnicity are important factors that contribute to different opinions concerning perceived risks and sympathy brought by an autonomous shuttle operating on pedestrians'sidewalks.The text mining results revealed several patterns.While respondents who were against the operation focused on potential safety hazards and the crowdedness of the sidewalks,supporters focused on the expected improved mobility for people with disabilities.The findings from this study are expected to assist policymakers and vehicle manufacturers with pedestrian expectations and considerations related to risk and safety when sharing their walkways with the autonomous shuttle.
文摘Pavement condition monitoring and its timely maintenance is necessary to ensure the safety and quality of the roadway infrastructure. The International Roughness Index (IRI) is a commonly used measure to quantify road surface roughness and is a critical input to asset management. In Indiana, the IRI statistic contributes to roughly half of the pavement quality index computation used for asset management. Most agencies inventory IRI once a year, however, pavement conditions vary much more frequently. The objective of this paper is to develop a framework using crowdsourced connected vehicle data to identify and detect temporal changes in IRI. Over 3 billion connected vehicle records in Indiana were analyzed across 30 months between 2022 and 2024 to understand the spatiotemporal variations in roughness. Annual comparisons across all major interstates in Indiana showed the miles of interstates classified as “Good” decreased from 1896 to 1661 miles between 2022 and 2024. The miles of interstate classified as “Needs Maintenance” increased from 82 to 120 miles. A detailed case study showing monthly and daily changes of estimated IRI on I-65 are presented along with supporting dashcam images. Although the crowdsourced IRI estimates are not as robust as traditional specialized pavement profilers, they can be obtained on a monthly, weekly, or even daily basis. The paper concludes by suggesting a combination of frequent crowdsourced IRI and commercially available dashcam imagery of roadway can provide an agile and responsive mechanism for agencies to implement pavement asset management programs that can complement existing annual programs.
基金financial support from the 111 Project (Grant No. B13024)the National Science Foundation of China (Grant Nos. 51509024, 51678094 and 51578096)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. 106112017CDJQJ208848)the Special Financial Grant from the China Postdoctoral Science Foundation (Grant No. 2017T100681)
文摘Crushing of grains can greatly influence the strength,dilatancy,and stress-strain relationship of rockfill materials.The critical state line(CSL)in the void ratio versus mean effective stress plane was extended to the breakage critical state plane(BCSP).A state void-ratio-pressure index that incorporated the effect of grain crushing was proposed according to the BCSP.Rowe’s stress-dilatancy equation was modified by adding the breakage voidratio-pressure index,which was also incorporated into the formulations of the bounding stress ratio and plastic modulus.A BCSP-based bounding surface plasticity model was proposed to describe the state-dependent stressstrain behaviors and the evolution of grain crushing during shearing process of rockfill materials,and was shown to sufficiently capture the breakage phenomenon.
基金financial support from the National Science Foundation of China (Grant Nos. 51922024, 41831282, 51678094 and 51578096)
文摘Grain crushing is commonly encountered in deep foundation engineering,high rockfill dam engineering,railway engineering,mining engineering,coastal engineering,petroleum engineering,and other geoscience application.Grain crushing is affected by fundamental soil characteristics,such as their mineral strength,grain size and distribution,grain shape,density and specimen size,and also by external factors including stress magnitude and path,loading rate and duration,degree of saturation,temperature and geochemical environment.Crushable material becomes a series of different materials with the change in its grading during grain crushing,resulting in a decrease in strength and dilatancy and an increase in compressibility.Effects of grain crushing on strength,dilatancy,deformation and failure mechanisms have been extensively investigated through laboratory testing,discrete element method(DEM)modelling,Weibull statistics,and constitutive modelling within the framework of the extended crushing-dependent critical state theory or the energy-based theory.Eleven papers summarized in this review article for this special issue addressed the above issues in grain crushing through the advanced testing and modelling.
文摘Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, this work estimates local-scale vehicular emissions and concentrations near a highway traffic network, where a school zone is located in. In the case study, VISSIM traffic micro-simulation is used to estimate the source of vehicular emissions at each roadway segment. The local-scale emission sources are then used as inputs to the California line source dispersion model(CALINE4) to estimate concentrations across the study area. To justify the local-scale emissions modeling approach, the simulation experiment is conducted under various traffic conditions. Different meteorological conditions are considered for emission dispersion. The work reveals that emission concentrations are usually higher at locations closer to the congested segments, freeway ramps and major arterial intersections. Compared to the macroscopic estimation(i.e. using network-average emission factors), the results show significantly different emission patterns when the local-scale emission modeling approach is used. In particular, it is found that the macroscopic approach over-estimates emission concentrations at freeways and under-estimations are observed at arterials and local streets. The results of the study can be used to compare to the US environmental protection agency(EPA) standards or any other air quality standard to further identify health risk in a fine-grained manner.
文摘This paper presents the results from a case study highlighting the difficulties of pile driving in diatomaceous soils.In the companion(first)paper to this article,results of an extensive laboratory and in situ testing program were presented while the results from pile driving and further analysis of field observations were presented herein.Unexpected high pile rebound(HPR)was observed during driving of a closed-end pipe pile,with refusal occurring at a depth of less than 5 m.Subsequent open-ended piles were thus driven.Piezometer and case pile wave analysis program(CAPWAP)data were collected during driving of both closed-and open-end piles.Piezometer data indicated that negative pore water pressures(PWPs)were generated while the closed-ended pile exhibited high rebound.Results from in situ tests indicated change in material stiffness and strong dilative tendencies near the depth of refusal.A hypothesis for observed behavior was proposed that considers the soil beneath the pile as a medium with an effectively infinite bulk modulus.
基金Science and Technology Authority of Taiwan under Grant No.107-2221-E-492-004-
文摘Viscoelastic（VE） dampers, with their stiffness and energy dissipation capabilities, have been widely used in civil engineering for mitigating wind-induced vibration and seismic responses of structures, thus enhancing the comfort of residents and serviceability of equipment inside. In past relevant research, most analytical models for characterizing the mechanical behavior of VE dampers were verified by comparing their predictions with performance test results from small-scale specimens, which might not adequately or conservatively represent the actual behavior of full-scale dampers, especially with regard to the ambient temperature, temperature rise, and heat convection effects. Thus, in this study, by using a high-performance testing facility with a temperature control system, full-scale VE dampers were dynamically tested with different displacement amplitudes, excitation frequencies, and ambient temperatures. By comparing the analytical predictions with the experimental results, it is demonstrated that adopting the fractional derivative method together with considering the effects of excitation frequencies, ambient temperatures, temperature rises, softening, and hardening, can reproduce the design performance of full-scale VE dampers very well.
文摘Although pre-Northridge earthquake steel moment resisting frame buildings have been shown to be susceptible to brittle connection failures,they still represent a large fraction of the existing steel buildings in the United States of America.In this study,the performance of the 3-and 9-story Los Angeles pre-Northridge SAC buildings are analyzed considering ductile and brittle beam-column connection failures,and their uncertainty.This paper contributes to understanding the influence of uncertainty associated with connections brittle fracture on building interstory deformation capacity and its impact on bias and variability of fragility functions and loss assessment.The results show that considering brittle connections leads to significantly l arger d rift demands a nd t o h igher r epair costs,particularly under intense ground shaking.New fragility curve parameters are derived that account for the effect of the uncertainty of the strength and deformation capacity of brittle connections.
基金This work was in part sponsored by the 2015-2016 California State University Long Beach Research,Scholarship and Creative Activity(RSCA)Award。
文摘Higher-order multiscale structures are proposed to predict the effective elastic properties of 3-phase particle reinforced composites by considering the probabilistic spherical particles spatial distribution,the particle interactions,and utilizing homogenization with ensemble volume average approach.The matrix material,spherical particles with radius a1,and spherical particles with radius a2,are denoted as the 0th phase,the 1st phase,and the 2nd phase,respectively.Particularly,the two inhomogeneity phases are different particle sizes and the same elastic material properties.Improved higher-order(in ratio of spherical particle sizes to the distance between the centers of spherical particles)bounds on effective elastic properties of 3-phase particle reinforced proposed Formulation II and Formulation I derive composites.As a special case,i.e.,particle size of the 1st phase is the same as that of the 2nd phase,the proposed formulations reduce to 2-phase formulas.Our theoretical predictions demonstrate excellent agreement with selected experimental data.In addition,several numerical examples are presented to demonstrate the competence of the proposed frameworks.
文摘Accuracy of hydrodynamic and water quality numerical models developed for a specific site is dependent on multiple model parameters and variables whose values are attained via calibration processes and/or expert knowledge. Real time variations in the actual aquatic system at a site necessitate continuous monitoring of the system so that model parameters and variables are regularly updated to reflect accurate conditions. Multiple sources of observations can help adjust the model better by providing benefits of individual monitoring technology within the model updating process. For example, remote sensing data provide a spatially dense dataset of model variables at the surface of a water body, while in-situ monitoring technologies can provide data at multiple depths and at more frequent time intervals than remote sensing technologies. This research aims to present an overview of an integrated modeling and data assimilation framework that combines three-dimensional numerical model with multiple sources of observations to simulate water column temperature in a eutrophic reservoir in central Indiana. A variational data assimilation approach is investigated for incorporating spatially continuous remote sensing temperature observations and spatially discrete in-situ observations to change initial conditions of the numerical model. The results demonstrate the challenges in improving the model performance by incorporating water temperature from multi-spectral remote sensing analysis versus in-situ measurements. For example, at a eutrophic reservoir in Central Indiana where four images of multi-spectral remote sensing data were assimilated in the numerical model, the overall error for the four images reduced from 20.9% (before assimilation) to 15.9% (best alternative after the assimilation). Additionally, best improvements in errors were observed on days closer to the starting time of model’s assimilation time window. However, when the original and updated model results for the water column temperature were compared to the in-situ measurements during the data assimilation period, the error was found to have actually increased from 1.8℃ (before assimilation) to 2.7℃ (after assimilation). Sampling depth differences between remote sensing observations and in-situ measurements, and spatial and temporal sampling of remote sensing observations are considered as possible reasons for this contrary behavior in model performance. The authors recommend that additional research is needed to further examine this behavior.
文摘This study compares the effect of treated pineapple leaves fibres (T-PALF) with sodium hydroxide solution and untreated fibres (N-PALF) on the compressive and flexural strength of earth bricks stabilized with 3% and 5% cement. The fibre content ranged from 0% to 5% in steps of 1% by weight. The compressive strength tests were made at 7, 14, 21 and 28 days of curing;the flexural strength test were conducted at 28th day only. The results show that the T-PALF had a higher compressive strength when comparing to the N-PALF. The highest compressive strength of the bricks was obtained at 28 days of curing. The compressive strength at 28 days of stabilized brick at 3% and 5% of cement reinforced with T-PALF were 4.01 and 4.81 MPa, respectively, while the one reinforced with N-PALF was 3.19 and 4.63 MPa, respectively. The results further show that the highest flexural strength of both stabilized bricks at 3% and 5% of cement reinforced with T-PALF and N-PALF was obtained with the bricks stabilized with 5% of cement reinforced with T-PALF. This results show that bricks stabilized with 5% cement and reinforced with 3% of treated fibres content are good for construction of load bearing walls. It was observed;a significant improvement of the reinforced blocks under flexure than under compression.
文摘Safe water of adequate quantity, and dignified sanitation, is vital for the sustenance of a healthy and productive human population. In the recognition of this, the United Nations formulated the Sustainable Development Goal No. 6 to ensure access to safe water and sanitation by all by 2030. Actualization of this Goal requires information on the existing status of water resources and sanitation levels. Knowledge on contamination of groundwater is essential to prevent risks to human health. The objective of this study was to determine groundwater contamination in Kisumu, Kenya. A total of 275 water samples were collected from 22 sites within the informal settlements between December 2016 and December 2017. The samples were analysed for bacterial contamination and physical chemical quality. Thermal tolerant coliform bacteria enumeration was used as a proxy to bacteria contamination, and the pH, turbidity, dissolved oxygen, conductivity, salinity and temperature were used as physical chemical indicators of contamination. The results indicate that groundwater in Kisumu hosed coliform bacteria and therefore didn’t comply with contamination limits for domestic water proposed by WHO and local KEBS standards. The results further indicated that the levels of bacteriological contamination vary with water type, shallow well having the highest bacterial loads. The study concluded that there were potential risks to human health due to high content of coliform bacteria. The study attributed the contribution to pit latrines that were present in virtually all compounds. The pit latrines are located close to the water points. The study recommended the definition of minimum distance between the pit latrines and shallow wells to minimize contamination. The low income dwellers should be educated on simple ways of treating drinking water contaminated by microbial to minimize enteric infections.
文摘This work aims at solving the problems of difficult dispersion,easy oxidation and high cost of nano carbon during application,carbon/magnesium aluminate spinel(C/MgAl_(2)O_(4))composite powders were prepared using MgC2O4·2H2O,MgO2,Al2O3 powder,and Al powder as raw materials by combustion synthesis.The results indicate that with the maximum MgC2O4·2H2O addition of 33.34 mass%,the prepared powder contains 1.17 mass%of carbon and carbon distributes among spinel grains.The MgAl_(2)O_(4)spinel shows both granular and rod-like morphologies.The granular MgAl_(2)O_(4)spinel is generated from mutual diffusion between MgO and Al2O3;while the rod-like MgAl_(2)O_(4)spinel is mainly formed by the vapor-solid growth mechanism from Mg vapor and Al2O3.
文摘Many studies have been conducted by analyzing crash data that included road profile, site conditions, vehicle configurations and weights, driver behavior, etc.. However, limited studies have been conducted evaluating the impact of these factors on crashes and/or rollover through simulations. This is mainly due to lack of availability of verified full vehicle flexible-body models. The verification process is costly as it requires instrumentation of a heavy vehicle, scanning of road surfaces, and collection of data by running the vehicle over different road conditions, performing various maneuvering, etc. This paper presents the reverse engineering process of a class-8 truck and validation of a full flexible-body simulation model of a Wabash 53-foot trailer against the strain data recoded from proving ground testing of an instrumented truck. Simulation results show that, with the exception of the noise from the strain gage data from instrumented test run at 30 mph, there is a good agreement in periodicity and relative amplitude with the ADAMS model. A comparison of strain data from the flex-body model and the instrumented truck shows that the modeling and verification approach presented in this paper can be confidently used to validate the full flexible-body models developed for specific analyses.
文摘This experimental research is focused on the effect of concrete made by incorporating lime treated Palm Kernel Shell (PKS) & Sugarcane Bagasse Ash (SCBA) as partial replacements of coarse aggregates and Ordinary Portland Cement (OPC) respectively. An experimental analysis for concrete grade 30 with a mix design ratio of 1:1.97:3.71 of cement:fine aggregates:coarse aggregates with a constant water to cement ratio of 0.5, was used. Physical tests such as workability on fresh concrete and water absorption on hardened concrete of each batch were carried out. Mechanical tests like compressive strength and split tensile strength were carried out on hardened concrete cubes (100 mm × 100 mm × 100 mm) and cylinders (100 mm × 200 mm) at 7 and 28 days. The experimental results obtained in this study indicate the possibility of using up 15% of lime treated PKS and 10% of SCBA for production of structural concrete.
基金the research result of the project"Research and Analysis of the Recycling and Utilization of Waste Concrete Based on Energy-saving and Environmental Protection"PJ20201390519 of the project of"Innovation and Entrepreneurship Training Program for College Students in 2020".Instructor:Congrong Tang。
文摘The early asphalt pavement in our country severely reduced the road performance due to various external factors during the use process.According to incomplete statistics,there are more asphalt pavements that need to be renovated and repaired every year in China,and the amount of construction waste such as asphalt concrete and other construction waste reaches 1,000.About ten thousand tons.If such a huge amount of construction waste is not used,it will inevitably cause great pollution to the environment.If it can be reused,not only will it be environmentally friendly and energy-saving,it will also save more than one billion yuan in costs.In view of the above problems,this article conducts related Research and Analysis on the Principle in Plant Cold Recycling for Foamed Bitumen and Mixture Performance to provide reference for future projects.
