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Comparative evaluation of roundabout capacities under heterogeneous traffic conditions

Journal of Modern Transportation 2015年第4期23卷 310-324页

作者： Ramu Arroju Hari krishna Gaddam Lakshmi Devi Vanumu k.Ramachandra Rao Department of Civil Engineering IIT Delhi Department of Civil Engineering and Transportation Research and Injury Prevention Programme (TRIPP) IIT Delhi

In heterogeneous traffic conditions, roundabout capacity is described by vehicle and driver characteristics which are different from traffic conditions in homogeneous conditions. In the present study, the capacity of the roundabout is determined using various capacity formulas such as gap acceptance models given by Highway Capacity Manual 2010 （US）, German model （2001）; empirical regression models given by TRRL （Uk） and weaving models given by IRC： 65-1976 （India）. In addition, microscopic simulation model like VISSIM （PTV Ger- many） is also used to derive capacity values. Unlike the other capacity estimation models, VISSIM is helpful in estimating capacity values using geometric and driver characteristics and it can also simulate heterogeneous traffic condition accurately. Capacity is estimated after calibrating the simulation model （VISSIM） developed for the roundabout. This is achieved by incorporating different vehicle classes to represent the heterogeneous traffic environment, driver gap acceptance, and lane changeparameters. All the required inputs were extracted from the video using semi-automatic data collection methods. Data are used for the estimation of capacity values from dif- ferent methods mentioned above and for the calibration and validation of simulation model. The capacity values esti- mated form various formulas except German model are distinctly different from the field values and they are either overestimating or underestimating. Analysis of these observations reveals that the capacity values from VISSIM and German models are nearly matching with the field capacity.

关键词： Roundabout Capacity VISSIM Simulation Heterogeneous

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Community-based interventions for the prevention and control of helmintic neglected tropical diseases

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Infectious Diseases of Poverty 2014年第1期3卷 206-222页

作者： Rehana A Salam Hasina Maredia Jai k Das Zohra S Lassi Zulfiqar A Bhutta Division of Women and Child Health The Aga Khan UniversityKarachi 74800Pakistan Brown University ProvidenceRIUSA Center of Excellence in Women&Child Health The Aga Khan UniversityKarachiPakistan Center for Global Child Health Hospital for Sick Children TorontoCanada

In this paper,we aim to systematically analyze the effectiveness of community-based interventions(CBIs)for the prevention and control of helminthiasis including soil-transmitted helminthiasis(STH)(ascariasis,hookworms,and trichuriasis),lymphatic filariasis,onchocerciasis,dracunculiasis,and *** systematically reviewed literature published before May 2013 and included 32 studies in this *** from the meta-analysis suggest that CBIs are effective in reducing the prevalence of STH(RR:0.45,95%CI:0.38,0.54),schistosomiasis(RR:0.40,95%CI:0.33,0.50),and STH intensity(SMD:−3.16,95 CI:−4.28,−2.04).They are also effective in improving mean hemoglobin(SMD:0.34,95%CI:0.20,0.47)and reducing anemia prevalence(RR:0.90,95%CI:0.85,0.96).However,it did not have any impact on ferritin,height,weight,low birth weight(LBW),or ***-based delivery significantly reduced STH(RR:0.49,95%CI:0.39,0.63)and schistosomiasis prevalence(RR:0.50,95%CI:0.33,0.75),STH intensity(SMD:−0.22,95%CI:−0.26,−0.17),and anemia prevalence(RR:0.87,95%CI:0.81,0.94).It also improved mean hemoglobin(SMD:0.24,95%CI:0.16,0.32).We did not find any conclusive evidence from the quantitative synthesis on the relative effectiveness of integrated and non-integrated delivery strategies due to the limited data available for each ***,the qualitative synthesis from the included studies supports community-based delivery strategies and suggests that integrated prevention and control measures are more effective in achieving greater coverage compared to the routine vertical delivery,albeit it requires an existing strong healthcare *** evidence suggests that effective community-based strategies exist and deliver a range of preventive,promotive,and therapeutic interventions to combat helminthic neglected tropical diseases(NTDs).However,there is a need to implement and evaluate efficient integrated programs with the existing disease control programs on a larger scal

关键词： Neglected tropical diseases Soil-transmitted helminthiasis Community-based interventions

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Age hardening,fracture behavior and mechanical properties of QE22 Mg alloy

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Journal of Magnesium and Alloys 2015年第3期3卷 210-217页

作者： F.khan MD S.k.Panigrahi Department of Mechanical Engineering Indian Institute of Technology MadrasChennai 600036India

The microstructure,mechanical properties and fracture behavior of an as-received QE22 alloy have been investigated under different thermal conditions,including solution treated(ST),under aged(UA),peak aged(PA)and over aged(OA)conditions.A significant increase in hardness of 27%,yield strength of 60%and ultimate tensile strength of 19%was observed in peak aged sample as compared to solution treated *** improvements of mechanical strength properties are mainly associated with the metastable λ and β′*** growth was not observed in the ST samples after subjecting to UA and PA treatments due to the presence of eutectic Mg_(12)Nd particles along the grain *** over aged sample,significant grain growth occurred because of dissolution of eutectic phase *** natures of crack initiation and propagation were observed under different thermal conditions during tensile testing at room *** mode of failure of solution treated sample is transgranular,cleavage and twin boundary fractures.A mixed mode of transgranular,intergranular,cleavage and twin boundary failure is observed in both peak aged and over aged samples.

关键词： Magnesium alloy(QE22) Age hardening behavior Microstructure Mechanical properties Fracture

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Preparation of Anhydrate Phosphogypsum Binders

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武汉理工大学学报 2010年第17期32卷 193-195,200页

作者： YANG M XIE Y CHENG J k PANG Y School of Chemistry and Chemical Engineering Guizhou UniversityGuiyang 550003China

In this work,phosphogypsum(PG) with a small amount of lime was thermally pretreated at 450 ℃ to produce anhydrate gypsum for the purpose of searching new ways for utilization of waste PG. Additives,k2SO4 and one selected seed crystal(SC),were used as activator for anhydrate PG. The hydration characteristics of the anhydrate PG binders were investigated by determination of the setting time,the ratio of hydrated anhydrate PG,the compressive strength development,and the microstructure of the hardenite. The resistance to water was studied by measuring mass loss of binders exposed to hydrodynamic water. Results suggest that activated by k2SO4 and SC,anhydrate PG hydrates much more rapidly than that without additives. The anhydrate PG binder with k2SO4 and SC has proper setting time and good strength developments. SEM photos show that the set binders have hydrated products of rodlike and regularly shaped crystals. Those crystals connected closely,and the hardenite has a compact structure,which is beneficial to the obtainment of good properties.

关键词： anhydrate PG binders activator hydration

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Neural network modeling to evaluate the dynamic flow stress of high strength armor steels under high strain rate compression

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Defence Technology（防务技术） 2014年第4期10卷 334-342页

作者： Ravindranadh BOBBILI V.MADHU A.k.GOGIA Defence Metallurgical Research Laboratory Hyderabad 500058 India

An artificial neural network(ANN) constitutive model is developed for high strength armor steel tempered at 500 C, 600 C and 650 C based on high strain rate data generated from split Hopkinson pressure bar(SHPB) experiments. A new neural network configuration consisting of both training and validation is effectively employed to predict flow stress. Tempering temperature, strain rate and strain are considered as inputs, whereas flow stress is taken as output of the neural network. A comparative study on Johnsone Cook(Je C) model and neural network model is performed. It was observed that the developed neural network model could predict flow stress under various strain rates and tempering temperatures. The experimental stressestrain data obtained from high strain rate compression tests using SHPB, over a range of tempering temperatures(500e650 C), strains(0.05e0.2) and strain rates(1000e5500/s) are employed to formulate Je C model to predict the high strain rate deformation behavior of high strength armor steels. The J-C model and the back-propagation ANN model were developed to predict the high strain rate deformation behavior of high strength armor steel and their predictability is evaluated in terms of correlation coefficient(R) and average absolute relative error(AARE). R and AARE for the Je C model are found to be 0.7461 and 27.624%, respectively, while R and AARE for the ANN model are 0.9995 and 2.58%, respectively. It was observed that the predictions by ANN model are in consistence with the experimental data for all tempering temperatures.

关键词：人工神经网络模型高应变率高强度装甲钢流变应力可预测性压缩评估

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Screening for 26 per-and polyfluoroalkyl substances(PFAS)in German drinking waters with support of residents

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Eco-Environment & Health 2023年第4期2卷 235-242页

作者： Vanessa Ingold Alexander kämpfe Aki Sebastian Ruhl German Environment Agency Section II 3.3Schichauweg 5812307BerlinGermany German Environment Agency Section II 3.2Heinrich-Heine-Straße 1208645Bad ElsterGermany Technische Universität Berlin Chair of Water TreatmentKF4Straße des 17.Juni 13510623BerlinGermany

The occurrence of per-and polyfluoroalkyl substances(PFAS)in water cycles poses a challenge to drinking water quality and *** order to counteract the large knowledge gap regarding PFAS in German drinking water,89 drinking water samples from all over Germany were collected with the help of residents and were analyzed for 26 PFAS by high-performance liquid chromatography with tandem mass spectrometry(HPLC-MS/MS).The 20 PFAS recently regulated by sum concentration(PFAS_(∑20)),as well as six other PFAS,were quantified by targeted *** all drinking water samples,PFAS_(∑20 )was below the limit of 0.1μg/L,but the sum concentrations ranged widely from below the limit of quantification up to 80.2 ng/*** sum concentrations(PFASP4)of perfluorohexanesulfonate(PFHxS),perfluorooctanesulfonate(PFOS),perfluorooctanoate(PFOA),and perfluorononanoate of 20 ng/L were exceeded in two *** most frequently detected individual substances were PFOS(in 52%of the samples),perfluorobutanesulfonate(52%),perfluorohexanoate(PFHxA)(44%),perfluoropentanoate(43%)and PFHxS(35%).The highest single concentrations were 23.5 ng/L for PFHxS,15.3 ng/L for PFOS,and 10.1 ng/L for *** regionally elevated concentrations were identified,but some highly urbanized areas showed elevated *** of substitution PFAS,including 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate and 2,2,3-trifluor-3-[1,1,2,2,3,3-hexafluor-3-(trifluormethoxy)propoxy]-propanoate(anion of ADONA),were very low compared to regulated *** most frequently detected PFAS were examined for co-occurrences,but no definite correlations could be found.

关键词： Persistent chemicals Organic micro-pollutants EU drinking water directive Indicator PFAS Drinking water

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Factors associated with crash severities in built-up areas along rural highways of Nevada:A case study of 11 towns

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Journal of Traffic and Transportation Engineering(English Edition) 2017年第1期4卷 96-102页

作者： Pramen P.Shrestha k.Joseph Shrestha Department of Civil and Environmental Engineering and Construction University of Nevada Las VegasLas VegasNV 89154USA Department of Engineering Technology Surveyingand Digital MediaEast Tennessee State UniversityJohnson CityTN 37614USA

In 2014, 32,675 deaths were recorded in vehicle crashes within the United States. Out of these, 51% of the fatalities occurred in rural highways compared to 49% in urban highways. No specific crash data are available for the built-up areas along rural highways. Due to high fatalities in rural highways, it is important to identify the factors that cause the vehicle crashes. The main objective of this study is to determine the factors associated with se- verities of crashes that occurred in built-up areas along the rural highways of Nevada. Those factors could aid in making informed decisions while setting up speed zones in these built-up areas. Using descriptive statistics and binary logistic regression model, 337 crashes that occurred in 11 towns along the rural highways from 2002 to 2010 were analyzed. The results showed that more crashes occurred during favorable driving conditions, e.g., 87% crashes on dry roads and 70% crashes in clear weather. The binary logistic regression model showed that crashes occurred from midnight until 4 a.m. were 58.3% likely to be injury crashes rather than property damage only crashes, when other factors were kept at their mean values. Crashes on weekdays were three times more likely to be injury crashes than that occurred on weekends. When other factors were kept at their mean value, crashes involving motorcycles had an 80.2% probability of being injury crashes. Speeding was found to be 17 times more responsible for injury crashes than mechanical defects of the vehicle. As a result of this study, the Nevada Department of Transportation now can take various steps to improve public safety, including steps to reduce speeding and encourage the use of helmets for motorcycle riders.

关键词： Speed-zone guideline Crash severity Binary logistic regression model Rural highway Nevada department of transportation

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Total Synthesis Endeavors and Their Contributions to Science and Society: A Personal Account

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CCS Chemistry 2019年第1期1卷 3-37页

作者： k.C.Nicolaou Stephan Rigol Ruocheng Yu Department of Chemistry BioScience Research CollaborativeRice University6100 Main StreetHoustonTX 77005United States of America

The advent of organic synthesis in the 19th century,serendipitous as it was,set in motion a revolution in science that continues to evolve into increasing levels of sophistication and to expand into new domains of science and technology for the benefits of science and *** evolution was always driven by the chal-lenges posed by natural products,whose structures were becoming increasingly complex and diverse.

关键词： education and training method develop-ment molecules for biology and medicine natural products structural elucidation total synthesis

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Minimal conceptual models for tropical cyclone intensification

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Tropical Cyclone Research and Review 2022年第2期11卷 61-75页

作者： Michael T.Montgomery Roger k.Smith Department of Meteorology Naval Postgraduate SchoolMontereyCAUSA Meteorological Institute Ludwig-Maximilians UniversityMunichGermany

We examine a hierarchy of minimal conceptual models for tropical cyclone *** models are framed mostly in terms of axisymmetric balance *** the first set of models,the heating rate is prescribed in such a way to mimic a deep overturning circulation with convergence in the lower troposphere and divergence in the upper troposphere,characteristic of a region of deep moist *** the second set,the heating rate is related explicitly to the latent heat release of ascending air *** release of latent heat markedly reduces the local static stability of ascending air,raising two possibilities in the balance *** first possibility is that the effective static stability and the related discriminant in the Eliassen equation for the overturning circulation in saturated air,although small,remains positive so the Eliassen equation is globally *** second possibility,the more likely one during vortex intensification,is that the effective static stability in saturated air is negative and the Eliassen equation becomes locally *** models help to understand the differences between the early Ooyama models of 1968 and 1969,the Emanuel,1989 model,and the later Emanuel models of 1995,1997 and *** provide insight also into the popular explanation of the WISHE feedback mechanism for tropical cyclone *** implications for recent work are discussed.

关键词： Tropical cyclone intensification Conventional spin-up mechanism Minimal models Nonlinear boundary layer spin-up mechanism WISHE feedback Mechanism

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The epigenetics of CHARGE syndrome

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Frontiers in Biology 2016年第2期11卷 85-95页

作者： Nina k. Latcheva Rupa Ghosh Daniel R. Marenda Department of Biology Drexel University Philadelphia PA 19104 USA Program in Molecular and Cellular Biology and Genetics Drexel University College of Medicine Philadelphia PA 19129 USA Department of Neurobiology and Anatomy Drexel University College of Medicine Philadelphia PA 19129 USA

In biology, we continue to appreciate the fact that the DNA sequence alone falls short when attempting to explain the intricate inheritance patterns for complex traits. This is particularly true for human disorders that appear to have simple genetic causes. The study of epigenetics, and the increased access to the epigenetic profiles of different tissues has begun to shed light on the genetic complexity of many basic biological processes, both physiological and pathological. Epigenetics refers to heritable changes in gene expression that are not due to alterations in the DNA sequence. Various mechanisms of epigenetic regulation exist, including DNA methylation and histone modification. The identification, and increased understanding of key players and mechanisms of epigenetic regulation have begun to provide significant insight into the underlying origins of various human genetic disorders. One such disorder is CHARGE syndrome （OMIM #214800）, which is a leading cause of deaf-blindness worldwide. A majority of CHARGE syndrome cases are caused by haploinsufficiency for the CHD7 gene, which encodes an ATP-dependent chromatin remodeling protein involved in the epigenetic regulation of gene expression. The CHD7 protein has been highly conserved throughout evolution, and research into the function of CHD7 homologs in multiple model systems has increased our understanding of this family of proteins, and epigenetic mechanisms in general. Here we provide a review of CHARGE syndrome, and discuss the epigenetic functions of CHD7 in humans and CHD7 homologs in model organisms.

关键词： Drosophila kismet CHD7 CHARGE syndrome chromatin remodeling

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