WorldWideScience

Sample records for base course pavements

  1. 柔性基层和半刚性基层沥青路面有限元对比分析%Finite Element Comparative Analysis for Asphalt Pavement with Flexible Base Course and Semi-rigid Base Course

    Institute of Scientific and Technical Information of China (English)

    刘鹏飞; 杨刚; 梁乃兴

    2013-01-01

    Based on graded gravel bearing plate test this paper establishes formulae of constitutive model of nonlinear bearing capacity of base course materials of graded gravel and builds planar model of typical structure of asphalt pavement with flexible base course by means of ANSYS universal finite element software.The paper analyzes structural stress of asphalt pavement with aggregate base course and semirigid base course,including propagation laws of stress and strain of asphalt pavement with flexible base course under different stress conditions and propagation differences of stress and strain from asphalt pavement with semi-rigid base course.%通过级配碎石承载板试验建立级配碎石基层材料的非线性承载力本构模型公式,利用ANSYS通用有限元软件建立柔性基层沥青路面典型结构平面模型.对粒料基层沥青路面和半刚性基层沥青路面结构受力进行分析,包括柔性基层沥青路面在不同受力条件下应力、应变的传播规律以及与半刚性基层沥青路面之间的应力、应变传播差异.

  2. BEHAVIOR OF MODEL ASPHALT PAVEMENT CONTAINING A HYDRAULIC, GRADED IRON AND STEEL SLAG BASE-COURSE UNDER REPEATED PLATE-LOADING

    Science.gov (United States)

    Yoshida, Nobuyuki; Sugisako, Yasunari

    In this paper, the dynamic response of asphalt pave ment containing a hydraulic, graded iron and steel slag (hereafter called HMS) base-course under repeated plate-loading was investigated using a model asphalt pavement and the influence of hydraulicity on th e pavement behavior was discussed. The model pavement constructed was a 4-layer system consis ting of a dense-graded asphalt mix surface layer, a dense-graded asphalt mix binder-course, a HMS base-course and a Masado (heavily-weathered granitic sand) subgrade. A repeated plate-loading test was carri ed out so as to achieve a resilient state. It is shown that surface resilient deflection decreases as curing progresses and after 90 days, the deflection becomes almost half of the initial. Large horizontal tensile strains develop at the bottoms of binder- and base-course, which decrease significantly with curing. It is indicative that HMS base-course behaves like a stiffer plate resulting in a hard-to-deflect state due to the development of hydraulicity.

  3. 柔性路面级配碎石底基层施工质量控制措施%Construction Quality Control Measures for Graded Crushed-Stone Base Course of Flexible Pavement

    Institute of Scientific and Technical Information of China (English)

    张帆

    2001-01-01

    结合佛开高速公路施工实践,介绍柔性路面级配碎石底基层施工质量控制的做法和经验。%Combining the construction practice of Fokai Express Highway, it introduces the measures and experience of construction quality control for the graded crushed-stone base course of flexible pavement.

  4. Vibration molding technology and application of semi-rigid base course pavement%半刚性基层路面振动成型技术及应用

    Institute of Scientific and Technical Information of China (English)

    赵评宏

    2015-01-01

    The paper introduces semi-rigid base course material design and construction status in highway engineering,discusses vibration mold-ing technology features of semi-rigid base course pavement according to vibration molding technology principles,compares and analyzes merits and defects of static pressure molding and vibration molding method,and puts forward raw material quality control measures in vibration molding con-struction. As a result,it improves the anti-cracking and anti-fatigue properties of semi-rigid base course pavement,and prolongs the pavement u-tilization cycle.%介绍了公路工程中半刚性基层材料设计及施工现状,根据振动成型技术原理,论述了半刚性基层路面振动成型技术的特点,并对比分析了静压成型法与振动成型法的优缺点,提出了振动成型施工中原材料的质控措施,提高了半刚性基层路面的抗裂性和抗疲劳性,延长了路面使用寿命。

  5. Experimental Study and Engineering Application of Cement Stabilized Recycled Aggregate Pavement Base Course%水泥稳定再生集料基层性能试验研究与工程应用∗

    Institute of Scientific and Technical Information of China (English)

    胡忠辉; 贾致荣; 张文刚; 袁中玉; 高磊

    2016-01-01

    To study the feasibility of applying cement stabilized recycled aggregate to high⁃grade highway pavement base course, the technical indicators of recycled aggregate and natural aggregate were tested, the pavement performances of cement stabilized recycled aggregate were tested, and the first class highway test road was paved in northern Jiangsu area. The results show that the recycled aggregate reaches the material technical requirements of pavement base course. The strength of cement stabilized recycled aggregate with 4�5% cement totally using recycled aggregate meets the strength requirement of high⁃grade highway base course. The shrink age coefficient of cement stabilized recycled aggregate is higher, so more attention should be paid to the early maintenance. Obvious cracking was not found on the test road after being opened to traffic for three months.%为研究再生集料应用于高等级道路基层的可行性,对比测试了天然集料与再生集料的各项指标,进行了再生水泥稳定碎石路用性能试验研究,并铺筑了苏北地区某一级公路基层试验路。结果显示:再生集料满足路面基层材料的技术要求;水泥剂量4�5%、全再生集料水泥稳定碎石抗压强度满足规范及设计要求;再生水泥稳定碎石干缩系数较大,工程中需注意早期养护;试验路通车3个月后调查,没有发现明显开裂。

  6. The influence of recycled asphalt pavement on 20mm binder course mix performance

    OpenAIRE

    Tabakovic, Amir; Gibney, Amanda; Gilchrist, M. D.; McNally, Ciaran

    2006-01-01

    This paper presents the results of ongoing research on the mechanical performance of a 20mm binder course asphalt pavement mix incorporating recycled asphalt pavement (RAP). A series of binder course mixes were designed containing varying percentages of RAP. A mix made only from virgin material was selected as the control mix for the investigation. The effect of introducing RAP into the binder course mix was evaluated through a series of laboratory tests including the Marshall Test, Indire...

  7. Structural Design of Pavement Overlays Based on Functional Parameters

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper reports a practical pavement overlay design methodbased on PCI (Pavement Condition Index). Current pavement investigation method (JTJ 073-96) is compared to the ASTM D 5340, which is the standard test method for airport pavement condition evaluation initially developed for US Air Force. The deficiency in the calculation of PCI based on field data in JTJ 073 is discussed. The proposed design method is compared to AASHTO overlay design method with good agreement. The paper concludes with an example illustrating how the existing pavement structural capacity is related to pavement distress survey results. The presented design method can be used in the design for overlay rehabilitation of pavements of highways, urban streets and airports.

  8. Research on elastic modulus backcalculation of asphalt course using BP artificial neural network based on surface deflection basin of pavement%基于路表弯沉盆的BP人工神经网络反演沥青面层弹性模量研究

    Institute of Scientific and Technical Information of China (English)

    杨国良; 钟雯; 黄晓韵; 梁思敏; 何慧慧; 陈家驹

    2015-01-01

    Based on layered elastic theory,the elastic modulus of asphalt course in asphalt pavement was predicted using BP artificial neural network.According to the types of pavement structure in common use,the database of surface deflections with their corresponding structural parameters of asphalt course based on layered elastic theory was established.The elastic modulus backcalculation model of asphalt course in asphalt pavement was developed using BP artificial neural network to predict.The predictive results of asphalt course elastic modulus backcalculation using theoretical deflection basin and measured deflection basin indicate that the elastic modulus backcalculation model of asphalt course in asphalt pavement is of good predictive accuracy and reliability.It would provide the references with the elastic modulus backcalculation model of asphalt course to accurately and quickly estimate the conditions of asphalt course in asphalt pavement.%基于层状弹性体系理论,建立BP人工神经网络反演沥青路面沥青面层弹性模量预测模型,利用BP人工神经网络预测沥青路面沥青面层弹性模量.理论弯沉盆和实测弯沉盆反演沥青面层弹性模量的结果表明,建立的BP人工神经网络反演沥青路面沥青面层弹性模量模型具有良好的预测精度和可靠性,为评价沥青路面的沥青面层性能状况提供了参考.

  9. An Airport Pavement Traffic Simulation Based on CPN

    OpenAIRE

    Heng Hong-jun; Yang Jue

    2014-01-01

    According to the characteristics of airport pavement traffic, we discuss a method of building an airport pavement traffic model which is based on CPN theory and simulate a practical situation as well. The method overcomes the shortage of modelling with normal Petri Net theory, solves the difficult problems of airport pavement traffic such as complex traffic nets, frequent road changing, etc., refines the process of the model, and will be good for the model’s analysis and simulation.

  10. Plastic Damage Model to Evaluate the Fracture Size of Semi-Rigid Base Pavement

    Directory of Open Access Journals (Sweden)

    Cao Peng

    2013-01-01

    Full Text Available A simple supported beam model has been presented to simulate the response of semi-rigid pavement structure, which are consistent of the upper layer, middle layer, bottom layer, base and sub base course, during the cycle vehicle loading. This mechanics model coupled with plastic-damage mechanics model could simulate the limit broken of the pavement structure in condition that soil base layer losing bearing capacity gradually. In the meanwhile, numerical calculations based on preceding mechanics model, using the FEM software ABAQUS, have been used to define the broken size of beam. The results indicated that: when the size of simple supported beam expanded to 10 m, brittle damage could happen immediately, Just the standard vehicle loading (about 0.7 Mpa has been implement once. Objective of this study is to provide a physical and rather concrete explanation for the style and concept of the semi-rigid pavement brittle broken.

  11. Pavement structure mechanics response of flexible on semi-flexible overlay that based on the old cement concrete pavement damage

    Directory of Open Access Journals (Sweden)

    Jiang Ruinan

    2015-01-01

    Full Text Available The old cement pavement damage status directly affect the design of the paving renovation. Based on the state of the old road investigation, combined with the research data at home and abroad, use the control index that average deflection, deflection value and CBR value to determine the reasonable time to overlay. Draw up the typical pavement structure according to the principle of combination of old cement pavement overlay structure design, and calculated that the tensile stress and shear stress in asphalt layer ,semi-flexible layer and the tensile in the old cement pavement adopting BISA3.0 statics finite element analysis model when modulus in the old road was diminishing. Use the computed result to analyses the influence of old road damage condition the influence of pavement structure.

  12. Pavement Evaluation and Maintenance Decisions Based on Fuzzy Inference Systems

    Directory of Open Access Journals (Sweden)

    Beltrán-Calvo Gloria Inés

    2014-07-01

    Full Text Available The remaining service life and maintenance decisions of existing pavements are highly dependent on stiffness and deterioration conditions throughout their operation. A non-conventional fuzzy logic based methodology is proposed in this work to address the stiffness-deterioration condition and conservation decisions, by means of three Fuzzy Inference Systems. Analysis were conducted using a database gathered from field tests performed on three and four layer pavement systems, that included traditional layer structuring and pavements having a subbase stiffer than their granular base. Information about layer thicknesses, magnitude and severity of structural distresses, and parameters and indicators derived from deflection testing by impulse load devices were used. The developed systems, allowed representing expert knowledge and linguistic variables of subjective and qualitative nature, commonly used to describe the severity levels of deterioration; thus they can be involved into structural characterization of pavements. Results were also expressed linguistically, to facilitate their interpretation and understanding. Based on the high quality of results obtained, it seems reasonable to conclude that the proposed systems could be used confidently for assessing and making decisions about pavement conservation, with low computational cost.

  13. Low cost pavement marking materials based on plasticized sulfur

    Science.gov (United States)

    Dale, J. M.

    1982-04-01

    Pavement marking was made more cost effective by reducing the cost of the marking materials. A low cost marking material based on sulfur was developed. Elemental sulfur is a hard, brittle, crystalline material which, on heating, melts to a thin liquid that can be spray applied. If molten elemental sulfur is spray applied to the road as markings, it will on application solidify, crack and adhere poorly to the road. The first ten high speed trucks that ride over the markings will remove them. To make a useful sulfur based pavement marking material it was necessary to chemically modify (plasticize) the sulfur and mix it with fillers and pigments such that it had all of the characteristics desired of a pavement marking material. Yellow and white formulations were developed. For identification they were given the names YS-EIGHT and WS-EIGHT for the yellow and white formulations.

  14. Smart pavement sensor based on thermoelectricity power

    Science.gov (United States)

    Yu, Xiong; Zhang, Bin; Tao, Junliang; Liu, Zhen

    2010-04-01

    The aging infrastructure requires a proactive strategy to ensure their functionality and performance. Innovative sensors are needed to develop infrastructures that are intelligent and adaptive. A power supply strategy is among the crucial components to reduce the instrument cost and to ensure the long term function of these embedded sensors. This paper introduces the results of a preliminary study on using thermo-electricity generation to power sensors. This presents an innovative strategy for long term monitoring of pavement performance.

  15. Genetic Optimization Method of Asphalt Pavement Based on Rutting and Cracking Control

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Nowadays asphalt pavement structure bearing is not the main subject for pursuers to study.Comparatively,the pavement performance is more important and emphasized.Based on this,rutting and cracking analysis is introduced into pavement optimization.A optimization model based on these two considerations is also established.The genetic algorithms (GAs) is adopted to solve the model.It is an intellective method.This research provides a new idea and technique for asphalt pavement structure optimization.

  16. Utilize Cementitious High Carbon Fly Ash (CHCFA) to Stabilize Cold In-Place Recycled (CIR) Asphalt Pavement as Base Coarse

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Haifang; Li, Xiaojun; Edil, Tuncer; O' Donnell, Jonathan; Danda, Swapna

    2011-02-05

    The purpose of this study was to evaluate the performance of cementitious high carbon fly ash (CHCFA) stabilized recycled asphalt pavement as a base course material in a real world setting. Three test road cells were built at MnROAD facility in Minnesota. These cells have the same asphalt surface layers, subbases, and subgrades, but three different base courses: conventional crushed aggregates, untreated recycled pavement materials (RPM), and CHCFA stabilized RPM materials. During and after the construction of the three cells, laboratory and field tests were carried out to characterize the material properties. The test results were used in the mechanistic-empirical pavement design guide (MEPDG) to predict the pavement performance. Based on the performance prediction, the life cycle analyses of cost, energy consumption, and greenhouse gasses were performed. The leaching impacts of these three types of base materials were compared. The laboratory and field tests showed that fly ash stabilized RPM had higher modulus than crushed aggregate and RPM did. Based on the MEPDG performance prediction, the service life of the Cell 79 containing fly ash stabilized RPM, is 23.5 years, which is about twice the service life (11 years) of the Cell 77 with RPM base, and about three times the service life (7.5 years) of the Cell 78 with crushed aggregate base. The life cycle analysis indicated that the usage of the fly ash stabilized RPM as the base of the flexible pavement can significantly reduce the life cycle cost, the energy consumption, the greenhouse gases emission. Concentrations of many trace elements, particularly those with relatively low water quality standards, diminish over time as water flows through the pavement profile. For many elements, concentrations below US water drinking water quality standards are attained at the bottom of the pavement profile within 2-4 pore volumes of flow.

  17. Decision of National and Provincial Highway Asphalt Pavement Structure Based on Value Engineering

    OpenAIRE

    Yingwei Ren; Jingsong Shan

    2014-01-01

    It is important that decision of asphalt pavement structure requires overall considerations of the performance and financial investment. To have asphalt pavement structure fulfilling good reliability, the asphalt pavement structure decision was researched based on value engineering theory. According to the national and provincial highway investigation data in Shandong Province during the last decade, the asphalt pavement performance attenuation rules of traffic levels and asphalt layer thickn...

  18. Long Life Pavements; Firmes de larga duracion

    Energy Technology Data Exchange (ETDEWEB)

    Mateos Moreno, A.; Marron Fernandez, J. O.; Perez Ayuso, J.

    2009-07-01

    The existence of long-life pavements is not new; they have been built in Europe and the United States for decades. In fact, the concept arises from the observation of in-service roads; it was verified how particular pavements, initially designed for a 20-year service life, did not seem to have reduced the bearing capacity along the time, and its maintenance necessities had been exclusively focused on the wearing course. The base idea of long-life pavements is the existence of a fatigue threshold below which the damage produced by each load application is, in practice, zero or below the healing potential of the asphalt mix. The use practice of long-life pavements design considers a pavements constituted by three asphalt layers, each one with a very specific role: a wearing course that provides with the surface characteristics, an intermediate course that provides with most of the structural capacity and a base course that provides with the fatigue resistance. Furthermore, one of the particularities is the design against specific distress mechanisms. Maintenance strategy also presents specific particularities for long-life pavements. It is essentially focused on the detection of surface deterioration, and the appropriate and timely repair, before the damage extends beyond the wearing course, putting into risk the structural integrity of the pavement. Nowadays, this new way to conceive the design, the construction and the maintenance of road pavements, constitutes one of the main challenges for pavement engineering worldwide. (Author) 5 refs.

  19. FLEXIBLE PAVEMENT REHABILITATION DESIGN BASED ON PAVEMENT SERVICE LIFE TIME SPAN LEFT

    OpenAIRE

    Gamelyak, I.; Shevchuk, V.

    2005-01-01

    The design of flexible pavement rehabilitation is analysed in terms of durability-cost. A notion of the remaining service life span is described. the model of rehabilitation strategy selection is presented for both design project and operation stages. the results can be used in the pavement management system.

  20. Reliability-based performance simulation for optimized pavement maintenance

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Jui-Sheng, E-mail: jschou@mail.ntust.edu.tw [Department of Construction Engineering, National Taiwan University of Science and Technology (Taiwan Tech), 43 Sec. 4, Keelung Rd., Taipei 106, Taiwan (China); Le, Thanh-Son [Department of Construction Engineering, National Taiwan University of Science and Technology (Taiwan Tech), 43 Sec. 4, Keelung Rd., Taipei 106, Taiwan (China)

    2011-10-15

    Roadway pavement maintenance is essential for driver safety and highway infrastructure efficiency. However, regular preventive maintenance and rehabilitation (M and R) activities are extremely costly. Unfortunately, the funds available for the M and R of highway pavement are often given lower priority compared to other national development policies, therefore, available funds must be allocated wisely. Maintenance strategies are typically implemented by optimizing only the cost whilst the reliability of facility performance is neglected. This study proposes a novel algorithm using multi-objective particle swarm optimization (MOPSO) technique to evaluate the cost-reliability tradeoff in a flexible maintenance strategy based on non-dominant solutions. Moreover, a probabilistic model for regression parameters is employed to assess reliability-based performance. A numerical example of a highway pavement project is illustrated to demonstrate the efficacy of the proposed MOPSO algorithms. The analytical results show that the proposed approach can help decision makers to optimize roadway maintenance plans. - Highlights: > A novel algorithm using multi-objective particle swarm optimization technique. > Evaluation of the cost-reliability tradeoff in a flexible maintenance strategy. > A probabilistic model for regression parameters is employed to assess reliability-based performance. > The proposed approach can help decision makers to optimize roadway maintenance plans.

  1. USE OF RECLAIMED ASPHALT PAVEMENT WITH MILLED ROAD PAVEMENT LAYERS

    OpenAIRE

    Andrzej Plewa; Marta Wasilewska; Władysław Gardziejczyk; Paweł Gierasimiuk

    2015-01-01

    The article presents the results of research on the functional properties of asphalt mixes using RAP obtained from milling asphalt road pavements. Asphalt concrete AC 22P with 0%, 10%, 15% and 20% addition of RAP used for base course of road pavements were designed. It was found that asphalt mixes with RAP characterized by comparable and in some cases better functional properties compared to the asphalt mixes without RAP (0%). One should notice the influence of RAP on the performance and ...

  2. Base Course Modification through Stabilization using Cement and Bitumen

    Directory of Open Access Journals (Sweden)

    S. M. Marandi

    2009-01-01

    Full Text Available The main objectives of this research was to analyze the use of combined cement and bitumen emulsion in base course stabilization in details and examine its replacement with conventional pavement in regions with low quality materials and limited construction period. To conduct the objectives, the research divided into three phases. Phase I involved the optimization of cement and bitumen emulsion. In this case, a series of Indirect Tensile Strength (ITS, Unconfined Compressive Strength (UCS and Marshal Tests carried out. In the second phase, various alternative roadway sections examined for minimizing the pavement thickness and increasing the bearing capacity and finally in third phase, a Falling Weight Deflectometer (FWD machine used to examine the pavement bearing capacity for three sections of the roadway. It was found that, the optimum values to eliminate the creation of shrinkage cracks in the whole project and minimize the execution period and construction costs were 3% for both binders in stabilization and its replacement with conventional pavement method (i.e., stabilized layer with conventional sub-base and base layers. Also, FWD results showed that, the bearing capacity of the constructed pavement using stabilization method is far beyond the predicted values in pavement design. Furthermore, it was found that, with high inflation rate and political situation in the region, base stabilized method decreased the final roadway construction costs in compare with conventional pavement method.

  3. Decision of National and Provincial Highway Asphalt Pavement Structure Based on Value Engineering

    Directory of Open Access Journals (Sweden)

    Yingwei Ren

    2014-01-01

    Full Text Available It is important that decision of asphalt pavement structure requires overall considerations of the performance and financial investment. To have asphalt pavement structure fulfilling good reliability, the asphalt pavement structure decision was researched based on value engineering theory. According to the national and provincial highway investigation data in Shandong Province during the last decade, the asphalt pavement performance attenuation rules of traffic levels and asphalt layer thicknesses were developed, and then the road performance evaluation method was presented. In addition, the initial investments, the costs of road maintenance, and middle-scale repair in a period were analyzed. For the light traffic and medium traffic example, using the value engineering method, the pavement performance and costs of which thickness varies from 6 cm to 10 cm were calculated and compared. It was concluded that value engineering was an effective method in deciding the asphalt pavement structure.

  4. Mechanical Response Analysis of Asphalt Pavement Structure

    Directory of Open Access Journals (Sweden)

    Yu Zhenqing

    2015-11-01

    Full Text Available Generally, the Chinese designed life of the high- grade asphalt concrete pavement is required 15 years, however, the designed life of the road in surface is often lower than the designed life, and even premature failure. Especially in heavy traffic conditions, the early damage of some high grade-asphalt pavement in China is serious. According to some investigations, we founded the main reason of the long-life asphalt pavement is to determine the function of each structure layer. According to the stress of pavement structure layer, so as to select the structure layer materials. Based on the viewpoint of mechanics, asphalt pavement damage mode is divided into three categories, such as top-down crack, fatigue cracking and rutting. Therefore, this paper uses ANSYS finite element software as calculation tool, the combination of road vehicle load and the primary influence on asphalt pavement structure mechanics response characteristics were analyzed. In this paper, the method of analysis is control variable: that means under different vehicle axle load, only change surface layer modulus and observe the pavement structure mechanical response trends to compare the effect. By using the same method, the response of the pavement base course parameters to the pavement mechanical structure is analyzed.

  5. In-Situ Behavior of Geosynthetically Stabilized Flexible Pavement

    OpenAIRE

    Appea, Alexander Kwasi

    1997-01-01

    The purpose of a geotextile separator beneath a granular base, or subbase in a flexible pavement system is to prevent the road aggregate and the underlying subgrade from intermixing. It has been hypothesized that in the absence of a geotextile, intermixing between base course aggregate and soft subgrade occurs. Nine heavily instrumented flexible pavement test sections were built in Bedford County Virginia to investigate the benefits of geosynthetic stabilization in flexible pavements. ...

  6. Research on pavement crack recognition methods based on image processing

    Science.gov (United States)

    Cai, Yingchun; Zhang, Yamin

    2011-06-01

    In order to overview and analysis briefly pavement crack recognition methods , then find the current existing problems in pavement crack image processing, the popular methods of crack image processing such as neural network method, morphology method, fuzzy logic method and traditional image processing .etc. are discussed, and some effective solutions to those problems are presented.

  7. Applying AHP—Based CBR to Estimate Pavement Maintenance Cost

    Institute of Scientific and Technical Information of China (English)

    Jui-Sheng Chou

    2008-01-01

    The cost-efficacy control of maintenance operations in developing countries has become critical to the infrastructure asset management after highway construction.To effectively manage numerous projects annually with limited resources,it is necessary to reasonably estimate costs during the process of making maintenance project selection decisions.This study outlines the modeling of case-based reasoning (CBR) estimation that compares and retrieves the most similar instance across the case library.Four CBR ap- proaches were presented and assessed in terms of their mean absolute prediction error rates.The resulting model demonstrates the ability of estimating the pavement maintenance project costs with the satisfactory accuracy at the early stages.

  8. An Optimization Model for Design of Asphalt Pavements Based on IHAP Code Number 234

    Directory of Open Access Journals (Sweden)

    Ali Reza Ghanizadeh

    2016-01-01

    Full Text Available Pavement construction is one of the most costly parts of transportation infrastructures. Incommensurate design and construction of pavements, in addition to the loss of the initial investment, would impose indirect costs to the road users and reduce road safety. This paper aims to propose an optimization model to determine the optimal configuration as well as the optimum thickness of different pavement layers based on the Iran Highway Asphalt Paving Code Number 234 (IHAP Code 234. After developing the optimization model, the optimum thickness of pavement layers for secondary rural roads, major rural roads, and freeways was determined based on the recommended prices in “Basic Price List for Road, Runway and Railway” of Iran in 2015 and several charts were developed to determine the optimum thickness of pavement layers including asphalt concrete, granular base, and granular subbase with respect to road classification, design traffic, and resilient modulus of subgrade. Design charts confirm that in the current situation (material prices in 2015, application of asphalt treated layer in pavement structure is not cost effective. Also it was shown that, with increasing the strength of subgrade soil, the subbase layer may be removed from the optimum structure of pavement.

  9. Permeable pavement study (Edison)

    Data.gov (United States)

    U.S. Environmental Protection Agency — While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types...

  10. Application of matter-element analysis based on entropy right to evaluate the pavement condition in permafrost region

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Evaluation of pavement performance is one of the most important issues in a pavement-management system.By employing the concept of entropy,the matter-element model for evaluating pavement is established,and the weights of the evaluation indices are obtained from surveying data.By calculating the degree of dependence of the matter-element model,the pavement performance evaluation can be obtained by this method.The results show that the matter-element model based on entropy right has good performance for evaluating the pavement condition in permafrost region.

  11. Vehicle-Pavement Interaction

    OpenAIRE

    Khavassefat, Parisa

    2014-01-01

    Several aspects of vehicle-pavement interaction have been studied and discussed in this thesis. Initially the pavement response is studied through a quasi-static and a dynamic computationally efficient framework under moving traffic loads. Subsequently, a non-stationary stochastic solution has been developed in order to account for the effect of pavement surface deterioration on pavement service life.The quasi-static procedure is based on a superposition principle and is computationally favou...

  12. Reliability-based Design Procedure for Flexible Pavements

    OpenAIRE

    Dinegdae, Yared Hailegiorgis

    2015-01-01

    Load induced top-down fatigue cracking has been recognized recently as a major distress phenomenon in asphalt pavements. This failure mode has been observed in many parts of the world, and in some regions, it was found to be more prevalent and a primary cause of pavements failure. The main factors which are identified as potential causes of top down fatigue cracking are primarily linked to age hardening, mixtures fracture resistance and unbound layers stiffness. Mechanistic Empirical analytic...

  13. Investigating In Situ Properties of Recycled Asphalt Pavement with Foamed Asphalt as Base Stabilizer

    Directory of Open Access Journals (Sweden)

    Christina Plati

    2010-01-01

    Full Text Available The objective of the present study was to conduct a comprehensive field experiment for the in situ assessment of in-depth recycled asphalt pavement using foamed asphalt as a stabilization treatment for base works. For this purpose Nondestructive Testing (NDT data collected using the Falling Weight Deflectometer (FWD and Ground Penetrating Radar (GPR along a foamed asphalt recycled pavement section was thoroughly analysed. Critical issues including the stabilized material curing and the contribution of the asphalt layers to the structural properties of the in-depth recycled pavement are discussed. In addition, recommendations concerning the improvement of the structural condition of the in-depth recycled pavement are developed based on this practical approach of investigation using NDT.

  14. Investigating In Situ Properties of Recycled Asphalt Pavement with Foamed Asphalt as Base Stabilizer

    OpenAIRE

    Antonis Kaltsounis; Vasilis Papavasiliou; Andreas Loizos; Christina Plati

    2010-01-01

    The objective of the present study was to conduct a comprehensive field experiment for the in situ assessment of in-depth recycled asphalt pavement using foamed asphalt as a stabilization treatment for base works. For this purpose Nondestructive Testing (NDT) data collected using the Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) along a foamed asphalt recycled pavement section was thoroughly analysed. Critical issues including the stabilized material curing and the con...

  15. USE OF RECLAIMED ASPHALT PAVEMENT WITH MILLED ROAD PAVEMENT LAYERS

    Directory of Open Access Journals (Sweden)

    Andrzej Plewa

    2015-07-01

    Full Text Available The article presents the results of research on the functional properties of asphalt mixes using RAP obtained from milling asphalt road pavements. Asphalt concrete AC 22P with 0%, 10%, 15% and 20% addition of RAP used for base course of road pavements were designed. It was found that asphalt mixes with RAP characterized by comparable and in some cases better functional properties compared to the asphalt mixes without RAP (0%. One should notice the influence of RAP on the performance and durability of the asphalt mixtures, as compared to virgin asphalt mixtures (without RAP.

  16. New Asphalt Pavement Failure Criterion Based on Unifi ed Strength Theory

    Institute of Scientific and Technical Information of China (English)

    YANG Qun; CHEN Lu; WANG Ping; DAI Jingwang

    2015-01-01

    This study aims to introduce an appropriate analytical method for asphalt pavement based upon unified strength theory (UST). The traditional maximum shear stress strength theory (MSST) cannot describe the marked difference between tension strength and compressive strength or variable intermediate principal stress, which significantly affects the geotechnical materials. Our studies try to find a new asphalt pavement failure criterion that considers the influence of both tension-compression strength ratio and intermediate principal stress of asphalt mixture. In order to select a suitable theory on pavement material, the UST is introduced and compared with the traditional theory. Results show that the tension-compression strength ratio of asphalt mixture, which is used as a material parameter, dramatically affects the stress and stress distribution law in pavement; the pavement stress level increases dramatically after considering the intermediate principal stresses. Therefore, the UST which considers both tension-compression strength ratio and intermediate principal stress is more in line with the material characteristics of asphalt pavement.

  17. Building Asphalt Pavement with SBS-based Compound Added Using a Dry Process in Greenland

    DEFF Research Database (Denmark)

    Lee, Hosin; Kim, Yongjoo; Geisler, Nivi;

    2009-01-01

    -based compound seemed to affect the asphalt mix to become more flexible under the heavy loads. By adding SBS-based compound to asphalt mixtures using a “dry” process, it is expected that the pavement would become more resistant to rutting than a typical asphalt mixture used in Greenland while enduring its arctic...... PMA where it is formulated to melt and blend with asphalt quickly during a batch mixing process. The main objectives of this study are to (1) build asphalt pavement using asphalt mixtures with SBS-based compound added using a “dry” process at the batch plant and (2) evaluate its performance under...

  18. Comparative Evaluation of Pavement Crack Detection Using Kernel-Based Techniques in Asphalt Road Surfaces

    Science.gov (United States)

    Miraliakbari, A.; Sok, S.; Ouma, Y. O.; Hahn, M.

    2016-06-01

    With the increasing demand for the digital survey and acquisition of road pavement conditions, there is also the parallel growing need for the development of automated techniques for the analysis and evaluation of the actual road conditions. This is due in part to the resulting large volumes of road pavement data captured through digital surveys, and also to the requirements for rapid data processing and evaluations. In this study, the Canon 5D Mark II RGB camera with a resolution of 21 megapixels is used for the road pavement condition mapping. Even though many imaging and mapping sensors are available, the development of automated pavement distress detection, recognition and extraction systems for pavement condition is still a challenge. In order to detect and extract pavement cracks, a comparative evaluation of kernel-based segmentation methods comprising line filtering (LF), local binary pattern (LBP) and high-pass filtering (HPF) is carried out. While the LF and LBP methods are based on the principle of rotation-invariance for pattern matching, the HPF applies the same principle for filtering, but with a rotational invariant matrix. With respect to the processing speeds, HPF is fastest due to the fact that it is based on a single kernel, as compared to LF and LBP which are based on several kernels. Experiments with 20 sample images which contain linear, block and alligator cracks are carried out. On an average a completeness of distress extraction with values of 81.2%, 76.2% and 81.1% have been found for LF, HPF and LBP respectively.

  19. Optical fiber based sensing system design for the health monitoring of multi-layered pavement structure

    Science.gov (United States)

    Liu, Wanqiu; Wang, Huaping; Zhou, Zhi; Li, Shiyu; Ni, Yuanbao; Wang, Geng

    2011-11-01

    This paper introduces an optical fiber based sensing system design for multi-layered pavement structural health monitoring. The co-line and integration design of FBG (Fiber Bragg Gating) sensors and BOTDR (Brillouin Optical Time Domain Reflectometry) sensors will ensure the large scale damage monitoring and local high accurate strain measurement. The function of pavement structure multi-scale shape measurement will provide real time subgrade settlement and rutting information. The sensor packaging methodology and strain transfer problem of the system will also be discussed in this paper. Primary lab tests prove the potential and feasibility of the practical application of the sensing system.

  20. Relation Between PAHs and Coal-Tar-Based Pavement Sealant in Urban Environments (Invited)

    Science.gov (United States)

    Mahler, B. J.; van Metre, P. C.

    2010-12-01

    Since 2003, coal-tar-based sealant products have come under increased scrutiny as a source of PAHs in urban environments. Sealant (or sealcoat) is the black, shiny substance often applied to asphalt pavement, in particular parking lots and driveways, for esthetic and maintenance purposes. Coal-tar-based sealant, one of the two primary pavement sealant types on the market, typically is 20-35 percent coal-tar pitch, a known carcinogen that is more than 50 percent polycyclic aromatic hydrocarbons (PAHs). The PAH content of the coal-tar-based sealant product is about 1,000 times that of a similar, asphalt-based product, on average. This difference is reflected in regional differences in sealant use and PAH concentrations in pavement dust. In the central and eastern U.S., where the coal-tar-based formulation is prevalent, ΣPAH in mobile particles from sealed pavement have been shown to be about 1,000 times higher than in the western U.S., where the asphalt-based formulation is prevalent (the median ΣPAH concentrations are 2,200 mg/kg in the central and eastern U.S. and 2.1 mg/kg in the western U.S.). Source apportionment modeling indicates that, in the central and eastern U.S., particles from sealed pavement are contributing the majority of the PAHs in recently deposited (post-1990) lake sediment, with implications for ecological health, and that coal-tar-based sealant is the primary cause of upward trends in PAHs in U.S. urban lakes. From the standpoint of human health, research indicates that mobile particles from parking lots with coal-tar-based sealant are tracked indoors, resulting in elevated PAH concentrations in house dust. Coal-tar-based sealcoat being applied to an asphalt parking lot at the University of Texas Pickle Research Center.

  1. Mechanics based model for predicting structure-induced rolling resistance (SRR) of the tire-pavement system

    Science.gov (United States)

    Shakiba, Maryam; Ozer, Hasan; Ziyadi, Mojtaba; Al-Qadi, Imad L.

    2016-05-01

    The structure-induced rolling resistance of pavements, and its impact on vehicle fuel consumption, is investigated in this study. The structural response of pavement causes additional rolling resistance and fuel consumption of vehicles through deformation of pavement and various dissipation mechanisms associated with inelastic material properties and damping. Accurate and computationally efficient models are required to capture these mechanisms and obtain realistic estimates of changes in vehicle fuel consumption. Two mechanistic-based approaches are currently used to calculate vehicle fuel consumption as related to structural rolling resistance: dissipation-induced and deflection-induced methods. The deflection-induced approach is adopted in this study, and realistic representation of pavement-vehicle interactions (PVIs) is incorporated. In addition to considering viscoelastic behavior of asphalt concrete layers, the realistic representation of PVIs in this study includes non-uniform three-dimensional tire contact stresses and dynamic analysis in pavement simulations. The effects of analysis type, tire contact stresses, pavement viscoelastic properties, pavement damping coefficients, vehicle speed, and pavement temperature are then investigated.

  2. Implications of Use of Coal-Tar-Based Pavement Sealcoat on Urban Water Quality

    Science.gov (United States)

    Van Metre, P. C.

    2015-12-01

    Coal-tar-based (CT) sealcoat is used to protect and improve the appearance of asphalt pavement of driveways and parking lots primarily in the central and eastern U.S. and in Canada. CT sealcoat typically is 20 to 35% crude coal tar or coal-tar pitch and contains from 50,000 to 100,000 mg/kg polycyclic aromatic hydrocarbons (PAH), about 1,000 times more than asphalt-based (AS) sealcoat or asphalt itself. Tires and snowplows abrade the friable sealcoat surface into fine particles—median total PAH concentrations in dust from CT-sealcoated pavement are 2,200 mg/kg compared to a median concentration of 11 mg/kg for dust from unsealed pavement. Use of CT sealcoat has several implications for urban streams and lakes. Source apportionment modeling has indicated that, in regions where CT sealcoat is prevalent, particles from sealcoated pavement are contributing the majority of the PAHs to recently deposited lake sediment, often resulting in sediment concentrations above toxicity thresholds based on effects-based sediment quality guidelines. Acute 2-day laboratory toxicity testing of simulated runoff from CT-sealcoated pavement to a cladoceran (Ceriodaphnia dubia) and fathead minnows (Pimephales promelas) demonstrated that toxicity continues for samples collected for weeks or months following sealcoat application and that toxicity is enhanced by exposure to UV light. Using the fish-liver cell line RTL-W1, runoff collected as much as 36 days following CT-sealcoat application has been demonstrated to cause DNA damage and impair DNA repair capacity. These results demonstrate that CT runoff is a potential hazard to aquatic ecosystems and that exposure to sunlight can enhance toxicity and genetic damage. Recent research has provided direct evidence that restricting use of CT sealcoat in a watershed can lead to a substantial reduction in PAH concentrations in receiving water bodies.

  3. Dynamics of vehicle-pavement coupled system based on a revised flexible roller contact tire model

    Institute of Scientific and Technical Information of China (English)

    YANG ShaoPu; LI ShaoHua; LU YongJie

    2009-01-01

    A revised flexible roller contact tire model (RFRC tire model) is proposed, which considers not only the geometric and flexible filtering effect, but also tire damping and pavement displacement. A vehi-cle-pavement coupled system is modeled as a two DOF oscillator moving along a simply supported beam on a linear viscoelastic foundation. By using the Galerkin's and Direct Integral method, dynamical responses of the vehicle-pavement coupled system are obtained based on the RFRC tire model and the traditional single point contact tire model (SPC tire model). The simulation results are compared with test data and the validity of the proposed RFRC tire model is verified. Differences between the two models are also investigated. It is found that the dynamical behaviors for both models agree with each other quite well when road surface roughness is a long harmonic wave. On the other hand, they are different under short harmonic wave or impulse road excitation. Thus the RFRC tire model should be used to compute the tire force and investigate dynamical responses of vehicle and pavement.

  4. Analysis and design of a stabilized fly ash as pavement base material

    Energy Technology Data Exchange (ETDEWEB)

    A. Hilmi Lav; M. Aysen Lav; A. Burak Goktepe [Istanbul Technical University, Istanbul (Turkey). Faculty of Civil Engineering

    2006-11-15

    The main objective of this study is to utilize a class F fly ash as base material in road pavements. Since class F fly ashes do not manifest desirable engineering properties for this purpose, it was decided to stabilize the material with cement. Fly ash may be utilized with or without aggregate as a pavement layer. It should be noted that, in this research only aggregate free stabilized mixtures (fly ash and cement only) were used since the aim was to utilize high volumes of this waste material. Cement content in the stabilized, laboratory prepared samples were between 2%, 4%, 8%, and 10% by total weight. Initially, Texas triaxial test was carried out to justify the suitability of the fly ash as pavement material. Then, mechanical tests were performed to obtain the fundamental properties of the cement stabilized material in order to analyze the pavement structure. Under repeated wheel loading, fatigue cracking is the primary mode of failure of stabilized materials in which cracks initiate due to the repeated tensile stresses. Utilizing an accelerated full scale road test data for the fatigue performance of cement stabilized fly ash and performing a mechanistic-empirical design procedure, required layer thickness for different lives were obtained for different amount of cement content. 32 refs., 13 figs., 3 tabs.

  5. Dynamics of vehicle-pavement coupled system based on a revised flexible roller contact tire model

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A revised flexible roller contact tire model (RFRC tire model) is proposed, which considers not only the geometric and flexible filtering effect, but also tire damping and pavement displacement. A vehi- cle-pavement coupled system is modeled as a two DOF oscillator moving along a simply supported beam on a linear viscoelastic foundation. By using the Galerkin’s and Direct Integral method, dynamical responses of the vehicle-pavement coupled system are obtained based on the RFRC tire model and the traditional single point contact tire model (SPC tire model). The simulation results are compared with test data and the validity of the proposed RFRC tire model is verified. Differences between the two models are also investigated. It is found that the dynamical behaviors for both models agree with each other quite well when road surface roughness is a long harmonic wave. On the other hand, they are different under short harmonic wave or impulse road excitation. Thus the RFRC tire model should be used to compute the tire force and investigate dynamical responses of vehicle and pavement.

  6. Development of Mechanistic-Empirical Pavement Design for Tropical Climate Using Cement-Treated Base Layer

    Directory of Open Access Journals (Sweden)

    O. S. Aderinola

    2016-08-01

    Full Text Available A mechanistic-empirical pavement design method is developed characterising cement-treated base layers for pavement design in Nigeria or other similar tropical and subtropical countries. Asphalt Concrete surface, Subbase and Aggregate base were characterised based on back calculation data from Claros et al (1986 while cement-treated base layer was based on modulus tests that had been conducted by past researchers. Failure criteria for the Asphalt Concrete fatigue failure and the subgrade rutting failure were based on those by Claros and Ijeh (1987 for Nigerian pavements. Cracking criterion used for the cement-treated layer was that developed by Otee et al. (1982. The comparison between the Soil-Cement and Aggregate base showed that at a low Equivalent Single Axle Load (ESAL (0.5 million repetitions was considered, the use of Aggregate base was better than Soil-Cement base. That for Aggregate base and Cement-Treated Gravel Base showed that the Cement-Treated Gravel Base was better than the Aggregate base at high ESAL (2.5 million repetitions was considered

  7. Influence of Repeated Loading and Geosynthetic Reinforcement on Base Course Thickness over Soft Soil

    Directory of Open Access Journals (Sweden)

    Slamet Widodo

    2012-01-01

    Full Text Available Vehicle wheels at surface of pavement will pass through it many times. Pavement or base course over soft soil always needs a reinforcement.  Influence of repeated loading to thickness of base course and base course reinforced by geosynthetic is presented. Several existing methods as Giroud-Han, USA Corps of Engineers and DuPont Typar method respectively to calculate thickness of base course over soft soil using reinforcement material either geotextile or geogrid is presented and the influence of repeated loading will be compared. Results from calculation and analysis indicate that Giroud-Han method gives thickness of base course higher than other methods when CBR values of subgrade at least 2 %.

  8. A fully Bayesian before-after analysis of permeable friction course (PFC) pavement wet weather safety.

    Science.gov (United States)

    Buddhavarapu, Prasad; Smit, Andre F; Prozzi, Jorge A

    2015-07-01

    Permeable friction course (PFC), a porous hot-mix asphalt, is typically applied to improve wet weather safety on high-speed roadways in Texas. In order to warrant expensive PFC construction, a statistical evaluation of its safety benefits is essential. Generally, the literature on the effectiveness of porous mixes in reducing wet-weather crashes is limited and often inconclusive. In this study, the safety effectiveness of PFC was evaluated using a fully Bayesian before-after safety analysis. First, two groups of road segments overlaid with PFC and non-PFC material were identified across Texas; the non-PFC or reference road segments selected were similar to their PFC counterparts in terms of site specific features. Second, a negative binomial data generating process was assumed to model the underlying distribution of crash counts of PFC and reference road segments to perform Bayesian inference on the safety effectiveness. A data-augmentation based computationally efficient algorithm was employed for a fully Bayesian estimation. The statistical analysis shows that PFC is not effective in reducing wet weather crashes. It should be noted that the findings of this study are in agreement with the existing literature, although these studies were not based on a fully Bayesian statistical analysis. Our study suggests that the safety effectiveness of PFC road surfaces, or any other safety infrastructure, largely relies on its interrelationship with the road user. The results suggest that the safety infrastructure must be properly used to reap the benefits of the substantial investments. PMID:25897515

  9. DRAINAGE AND FLEXIBLE PAVEMENT PERFORMANCE

    Directory of Open Access Journals (Sweden)

    SIDDHARTHA ROKADE

    2012-04-01

    Full Text Available Providing adequate drainage to a pavement system has been considered as an important design consideration to prevent premature failures due to water related problems such as pumping action, loss of support, and rutting, among others. Most water in pavements is due to rainfall infiltration into unsaturated pavement layers, throughjoints, cracks, shoulder edges, and various other defects, especially in older deteriorated pavements. Water also seep upward from a high groundwater table due to capillary suction or vapour movements, or it may flow laterally from the pavement edges and side ditches. Providing adequate drainage to a pavement system has been considered as an important design consideration to ensure satisfactory performance of the pavement, particularly from the perspective of life cycle cost and serviceability. To minimize premature pavement distresses and to enhance the pavement performance, it is imperative to provide adequate drainage to allow infiltrated water to drain out from the base and sub-base, thus avoiding saturation of base and subgrade soils. This paper deals with the analysis of the impact of subsurface drainage on pavement system performance. The requirement ofeffective subsurface drainage for pavement performance is also discussed.

  10. Simplified Pavement Design for LPAs: Introduction to PaveXpress

    OpenAIRE

    Bonte, Dudley

    2015-01-01

    Simplified Pavement Design for LPA's; An introduction to and use of PaveXpress, a simplified, free, web-based pavement design scoping tool for roadway and parking lot pavements. The system was developed by Pavia Systems in partnership with the National Asphalt Pavement Association. PaveXpress creates technical sound pavement structural designs for flexible and rigid pavements based on widely accepted industry standards from the Association of State Highway Officials (AASHTO). The simplified p...

  11. GPR-based evaluation of strength properties of unbound pavement material from electrical characteristics

    Science.gov (United States)

    Benedetto, Andrea; D'Amico, Fabrizio; Tosti, Fabio

    2013-04-01

    the use of road material, typically employed for subgrade and subbase courses. Different types of soil ranging from group A1 to A4 by AASHTO soil classification system, are analyzed. As regards the laboratory experiments, material is gradually compacted in electrically and hydraulically isolated test boxes. A large metal sheet supports the experimental boxes, so that the transmitted GPR signal is totally reflected. GPR inspections are carried out for any compaction step up to the maximum density value available. Moreover, in-situ tests are carried out on targeted types of soil, with grain size distribution and texture comparable to those analyzed in laboratory environment. The results of this study confirm a promising correlation between the electric permittivities and the strength and deformation properties of the surveyed soils. Laboratory analyses show that the relationship between the relative permittivity and the bulk density is positive: the higher the density of the compacted soil sample, the higher the electric permittivity of the medium. Analogously, in-situ validation presents a good comparison between measured and predicted data. Percentage errors less than 20% demonstrate that a reliable prediction of Young Modulus using this GPR-based approach can be achieved.

  12. Numerical Analysis of Asphalt Pavements under Moving Wheel Loads

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The responses of the pavement in service are the basis for the design of the semi-rigid base course asphalt pavement.Due to the dynamic characteristics of wheel loads and the temperature loads,the dynamic response analysis is very significant.In this article, the dynamic analysis of asphalt pavement under moving wheel loads is carried out using finite element method coupled with non-reflective boundary method.The influences of the base modulus, thickness, the vehicle velocity, the tire pressure, and the contact condition at the interface are studied using parametric analysis.The results of numerical analysis show that it is not appropriate to simply increase the base modulus or thickness in the design.It would be beneficial if the base design is optimized synthetically.The increase of damping is also beneficial to the pavements because of the surface deflection and the stresses declination.Furthermore, the good contact condition at the interface results in good performance because it combines every layer of the pavement to work together.As overload aggravates the working condition of the pavement, it is not allowed.

  13. Coal-tar-based pavement sealcoat and PAHs: implications for the environment, human health, and stormwater management.

    Science.gov (United States)

    Mahler, Barbara J; Metre, Peter C Van; Crane, Judy L; Watts, Alison W; Scoggins, Mateo; Williams, E Spencer

    2012-03-20

    Coal-tar-based sealcoat products, widely used in the central and eastern U.S. on parking lots, driveways, and even playgrounds, are typically 20-35% coal-tar pitch, a known human carcinogen that contains about 200 polycyclic aromatic hydrocarbon (PAH) compounds. Research continues to identify environmental compartments-including stormwater runoff, lake sediment, soil, house dust, and most recently, air-contaminated by PAHs from coal-tar-based sealcoat and to demonstrate potential risks to biological communities and human health. In many cases, the levels of contamination associated with sealed pavement are striking relative to levels near unsealed pavement: PAH concentrations in air over pavement with freshly applied coal-tar-based sealcoat, for example, were hundreds to thousands of times higher than those in air over unsealed pavement. Even a small amount of sealcoated pavement can be the dominant source of PAHs to sediment in stormwater-retention ponds; proper disposal of such PAH-contaminated sediment can be extremely costly. Several local governments, the District of Columbia, and the State of Washington have banned use of these products, and several national and regional hardware and home-improvement retailers have voluntarily ceased selling them.

  14. Coal-tar-based pavement sealcoat and PAHs: implications for the environment, human health, and stormwater management

    Science.gov (United States)

    Mahler, Barbara J.; Van Metre, Peter C.; Crane, Judy L.; Watts, Alison W.; Scoggins, Mateo; Williams, E. Spencer

    2012-01-01

    Coal-tar-based sealcoat products, widely used in the central and eastern U.S. on parking lots, driveways, and even playgrounds, are typically 20-35% coal-tar pitch, a known human carcinogen that contains about 200 polycyclic aromatic hydrocarbon (PAH) compounds. Research continues to identify environmental compartments—including stormwater runoff, lake sediment, soil, house dust, and most recently, air—contaminated by PAHs from coal-tar-based sealcoat and to demonstrate potential risks to biological communities and human health. In many cases, the levels of contamination associated with sealed pavement are striking relative to levels near unsealed pavement: PAH concentrations in air over pavement with freshly applied coal-tar-based sealcoat, for example, were hundreds to thousands of times higher than those in air over unsealed pavement. Even a small amount of sealcoated pavement can be the dominant source of PAHs to sediment in stormwater-retention ponds; proper disposal of such PAH-contaminated sediment can be extremely costly. Several local governments, the District of Columbia, and the State of Washington have banned use of these products, and several national and regional hardware and home-improvement retailers have voluntarily ceased selling them.

  15. “路基路面”课程设计探索%Elementary Analysis on "Roadbed and Pavement" Course Design

    Institute of Scientific and Technical Information of China (English)

    赵桂娟

    2013-01-01

    "Roadbed and pavement" course design is essential supplement and deepening to theory teaching for curriculum design for Road and bridge students of civil engineering. In view of the current existing problems in the course design, combining with own teaching experience, the author prepared "Roadbed and pavement" course design task and guide book, from the use of three years, the effect is good.%“路基路面”课程设计是对土木工程专业路桥方向学生课堂理论教学的必要补充和深化.针对目前“路基路面”课程设计中存在的问题,结合自身教学经验,编制了“路基各面”课程设计任务书和指导书,从3年的使用情况看,效果良好.

  16. An elastoplastic model based on the shakedown concept for flexible pavements unbound granular materials

    Science.gov (United States)

    Habiballah, Taha; Chazallon, Cyrille

    2005-05-01

    Nowadays, the problem of rutting of flexible pavements linked to permanent deformations occurring in the unbound layers is taken into account only by mechanistic empirical formulas. Finite element modelling of realistic boundary value problems with incremental rheological models will lead to unrealistic calculation time for large cycle numbers. The objective of the authors is to present a simplified model which can be used to model the flexible pavements rutting with the finite elements framework. This method is based on the shakedown theory developed by Zarka which is usually associated to materials like steels. It has been adapted for granular materials by introducing a yield surface taking into account the mean stress influence on the mechanical behaviour and a dependency of the hardening modulus with the stress state. The Drucker-Prager yield surface has been used with a non-associated flow rule. Comparisons with repeated load triaxial tests carried out on a subgrade soil have been done. These comparisons underline the capabilities of the model to take into account the cyclic behaviour of unbound materials for roads. Finally, a discussion, dealing with the use of the simplified method within a finite element modelling of a full-scale experiment, is presented.

  17. GPR used in combination with other NDT methods for assessing pavements in PPP projects

    Science.gov (United States)

    Loizos, Andreas; Plati, Christina

    2014-05-01

    In the recent decades, Public-Private Partnerships (PPP) has been adopted for highway infrastructure procurement in many countries. PPP projects typically take the form of a section of highway and connecting roadways which are to be construction and managed for a given concession period. Over the course of the highway concession period, the private agency takes over the pavement maintenance and rehabilitation duties. On this purpose, it is critical to find the most cost effective way to maintain the infrastructure in compliance with the agreed upon performance measures and a Pavement Management Systems (PMS) is critical to the success of this process. For the prosperous operation of a PMS it is necessary to have appropriate procedures for pavement monitoring and evaluation, which is important in many areas of pavement engineering. Non Destructive Testing (NDT) has played a major role in pavement condition monitoring, assessments and evaluation accomplishing continuous and quick collection of pavement data. The analysis of this data can lead to indicators related to trigger values (criteria) that define the pavement condition based on which the pavement "health" is perceived helping decide whether there is the need or not to intervene in the pavement. The accomplished perception appoints required management activities for preserving pavements in favor not only of the involved highway/road agencies but also of users' service. Amongst NDT methods Ground Penetrating Radar (GPR) seems to be a very powerful toll, as it provides a range of condition and construction pavement information. It can support effectively the implementation of PMS activities in the framework of pavement monitoring and evaluation. Given that, the present work aims to the development and adaptation of a protocol for the use of GPR in combination with other NDT methods, such as Falling Weight Deflectometer (FWD), for assessing pavements in PPP projects. It is based on the experience of Laboratory of

  18. Theoretical Development and Engineering Practice of Pavements in China

    Institute of Scientific and Technical Information of China (English)

    QIU Yan-jun

    2008-01-01

    This paper presents a comprehensive review of historical theory development and current construction practice of pavement engineering in China. Mechanical models, design guides, construction techniques, evaluation methods and maintenance standards are elaborated for Portland cement concrete (PCC) pavements and asphalt concrete (AC) pavements. Differences in design methodology among pavements of rural highways, urban roads and airport fields are discussed based on service requirements.Lessons and experiences based on the past 20 years' construction practice and pavement performance are summarized. Current research areas in pavement engineering associated with unconventional geological and/or landscaping in China's highway construction and national strategic plan for pavement engineering are also covered.

  19. Analytical prediction and field validation of transient temperature field in asphalt pavements

    Institute of Scientific and Technical Information of China (English)

    陈嘉祺; 李亮; 汪浩

    2015-01-01

    This work presented the development and validation of an analytical method to predict the transient temperature field in the asphalt pavement. The governing equation for heat transfer was based on heat conduction radiation and convection. An innovative time-dependent function was proposed to predict the pavement surface temperature with solar radiation and air temperature using dimensional analysis in order to simplify the complex heat exchange on the pavement surface. The parameters for the time-dependent pavement surface temperature function were obtained through the regression analysis of field measurement data. Assuming that the initial pavement temperature distribution was linear and the influence of the base course materials on the temperature of the upper asphalt layers was negligible, a close-form analytical solution of the temperature in asphalt layers was derived using Green’s function. Finally, two numerical examples were presented to validate the model solutions with field temperature measurements. Analysis results show that the solution accuracy is in agreement with field data and the relative errors at a shallower depth are greater than those at a deeper one. Although the model is not sensitive to dramatic changes in climatic factors near the pavement surface, it is applicable for predicting pavement temperature field in cloudless days.

  20. Design and implementation of PAVEMON: A GIS web-based pavement monitoring system based on large amounts of heterogeneous sensors data

    Science.gov (United States)

    Shahini Shamsabadi, Salar

    A web-based PAVEment MONitoring system, PAVEMON, is a GIS oriented platform for accommodating, representing, and leveraging data from a multi-modal mobile sensor system. Stated sensor system consists of acoustic, optical, electromagnetic, and GPS sensors and is capable of producing as much as 1 Terabyte of data per day. Multi-channel raw sensor data (microphone, accelerometer, tire pressure sensor, video) and processed results (road profile, crack density, international roughness index, micro texture depth, etc.) are outputs of this sensor system. By correlating the sensor measurements and positioning data collected in tight time synchronization, PAVEMON attaches a spatial component to all the datasets. These spatially indexed outputs are placed into an Oracle database which integrates seamlessly with PAVEMON's web-based system. The web-based system of PAVEMON consists of two major modules: 1) a GIS module for visualizing and spatial analysis of pavement condition information layers, and 2) a decision-support module for managing maintenance and repair (Mℝ) activities and predicting future budget needs. PAVEMON weaves together sensor data with third-party climate and traffic information from the National Oceanic and Atmospheric Administration (NOAA) and Long Term Pavement Performance (LTPP) databases for an organized data driven approach to conduct pavement management activities. PAVEMON deals with heterogeneous and redundant observations by fusing them for jointly-derived higher-confidence results. A prominent example of the fusion algorithms developed within PAVEMON is a data fusion algorithm used for estimating the overall pavement conditions in terms of ASTM's Pavement Condition Index (PCI). PAVEMON predicts PCI by undertaking a statistical fusion approach and selecting a subset of all the sensor measurements. Other fusion algorithms include noise-removal algorithms to remove false negatives in the sensor data in addition to fusion algorithms developed for

  1. Prediction of Permanent Deformation of Pavement's Unbounded Layers Based on Cyclic Triaxial Tests

    Directory of Open Access Journals (Sweden)

    B. Žlender

    2008-01-01

    Full Text Available This research presents an analytical model for determining permanent deformation of pavement's sub grade and unbound granular base and sub-base material due to cyclic traffic loading. The model is given for interpreting results of repeated load triaxial tests. It considers long term elastoplastic behavior and resilient behavior of sub-grade and unbound granular material. Permanent deformations are expressed as a function of the number of loading cycles and the spherical component and the deviatoric component of the repeated loading. The permanent axial deformation is given as a function of the resilient modulus and the secant modulus for different states of spherical and distortional stresses, and number of loading cycles. By analytical derivation it is presented that the normalized permanent axial strain can be expressed with the modulus values and the parameter D. The moduli are expressed as the functions of the spherical stress component and the distortional stress component. The magnitude of normalized permanent axial strain depends on the limit value of the resilient modulus and ratios between resilient and secant modulus. The parameter D gives the shape of the change of the normalized permanent axial strain with the number of cycles, and is a function of the change of modules with the number of cycles. The applicability of the presented model is demonstrated on the practical example of a repeated load triaxial test of sub-base granular material.

  2. Evaluation and verification of two systems for mechanistic structural design of asphalt concrete pavements in Nebraska

    Science.gov (United States)

    Sneddon, R. V.

    1982-07-01

    The VESY-3-A mechanistic design system for asphalt pavements was field verified for three pavement sections at two test sites in Nebraska. PSI predictions from VESYS were in good agreement with field measurements for a 20 year old 3 layer pavement located near Elmwood, Nebraska. Field measured PSI values for an 8 in. full depth pavement also agreed with VESYS predictions for the study period. Rut depth estimates from the model were small and were in general agreement with field measurements. Cracking estimates were poor and tended to underestimate the time required to develop observable fatigue cracking in the field. Asphalt, base course and subgrade materials were tested in a 4.0 in. diameter modified triaxial cell. Test procedures used dynamic conditioning and rest periods to simulate service conditions.

  3. 半刚性基层沥青路面常见病害分析%Analysis of semi-rigid base asphalt pavement diseases

    Institute of Scientific and Technical Information of China (English)

    李晗

    2011-01-01

    半刚性基层沥青路面是国内应用最广泛的路面类型。沥青路面受施工水平、路基强度、温度变化、水损害、交通量增长及超限车辆等因素的影响,易出现多种病害。本文分析了沥青路面常见病害及其形成原因,并提出了减少沥青路面病害的预防措施,为沥青路面养护提供决策依据。%Asphalt pavement with semi-rigid base is the most national widely used type of pavement. Subgrade of asphalt pavement many occur many diseases under the influence of construction level, strength, temperature changes, moisture damage, traffic growth and oversize vehicles. This article analyses the common diseases of asphalt pavement and its causes, and suggests reducing asphalt pavement disease prevention measures for asphalt pavement maintenance decision-making basis.

  4. Permanent deformation of flexible pavements

    Science.gov (United States)

    Brown, S. F.; Broderick, B. V.; Pappin, J. W.

    1980-06-01

    Seven pairs of pavements with granular bases were tested under controlled conditions. One pavement in each pair contained fabric inclusions. An improved testing facility was developed, including: (1) servo-hydraulic system for the loading carriage; (2) amplification and read-out system for pressure cells; (3) linearizing unit for strain coils; (4) transducers for measuring vertical and resilient deflection; (5) techniques for measuring in situ strain on fabric inclusions; (6) extensive use of nuclear density meter to monitor pavement and foundation materials. The following conclusions are drawn: (1) No improvement in performance resulted from fabric inclusions. (2) No consistent reduction in in-situ stresses, resilient strains, or permanent strains was observed as a result of fabric inclusion. (3) No consistent improvement in densities resulted from fabric inclusions. (4) Some slip apparently occurred between fabric and soil on those pavements which involved large deformations. The slip occurred between fabric and crushed limestone base rather than between fabric and silty-clay subgrade.

  5. Research on segregation evaluation methods of asphalt pavement based on air voids distribution

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Eye observation was used to evaluate the segregation degree of asphalt pavement, which was not much creditable. To the asphalt pavement, road surface texture measuring method which has appeared recently can identify gradational segregation; but it can't reflect the influence of the temperature segregation. However,using infrared temperature detector to evaluate the segregation must be taken during paving, which brings much inconvenience. In this paper, measuring the air voids distribution using non-nuclear density gauge to evaluate asphalt pavement segregation was introduced. Result shows that this method can directly reflect the comprehensive results of the two types of segregation in a high efficient and accurate way. Moreover, using the sketch map of segregation area can help to analyze the segregation reason visually.

  6. Assessment of in-situ compaction degree of HMA pavement surface layers using GPR and novel dielectric properties-based algorithms

    Science.gov (United States)

    Georgiou, Panos; Loizos, Fokion

    2015-04-01

    Field compaction of asphalt pavements is ultimately conducted to achieve layer(s) with suitable mechanical stability. However, the achieved degree of compaction has a significant influence on the performance of asphalt pavements. Providing all desirable mixture design characteristics without adequate compaction could lead to premature permanent deformation, excessive aging, and moisture damage; these distresses reduce the useful life of asphalt pavements. Hence, proper construction of an asphalt pavement is necessary to develop a long lasting roadway that will help minimize future maintenance. This goal is achieved by verifying and confirming that design specifications, in this case density specifications are met through the use of Quality Assurance (QA) practices. With respect to in-situ compaction degree of hot mix asphalt (HMA) pavement surface layers, nearly all agencies specify either cored samples or nuclear/ non nuclear density gauges to provide density measurement of the constructed pavement. Typically, a small number of spot tests (with either cores or nuclear gauges) are run and a judgment about the density level of the entire roadway is made based on the results of this spot testing. Unfortunately, density measurement from a small number of spots may not be representative of the density of the pavement mat. Hence, full coverage evaluation of compaction quality of the pavement mat is needed. The Ground Penetrating Radar (GPR), as a Non Destructive Testing (NDT) technique, is an example of a non-intrusive technique that favors over the methods mentioned above for assessing compaction quality of asphalt pavements, since it allows measurement of all mat areas. Further, research studies in recent years have shown promising results with respect to its capability, coupled with the use of novel algorithms based on the dielectric properties of HMA, to predict the in-situ field density. In view of the above, field experimental surveys were conducted to assess the

  7. Study on Axle Load Conversion for Concrete Base of Durable Asphalt Pavement%耐久性沥青路面混凝土基层轴载换算研究

    Institute of Scientific and Technical Information of China (English)

    郑木莲; 陈拴发; 马庆雷

    2012-01-01

    刚性基层耐久性沥青路面作为一种新型的路面结构,现行规范对于上覆沥青层水泥混凝土路面的设计思路对其并不适用,其轴载换算公式由于没有考虑刚性基层沥青路面结构的特点,得出的结果存在较大误差.依据普通混凝土及贫混凝土的疲劳方程,结合耐久性沥青路面混凝土基层在标准轴载和不同轴-轮型荷载作用下回归得出的荷载应力计算公式,按照混凝土基层等效疲劳损伤原则,推求得出单轴-单轮、单轴-双轮组、双轴-双轮组荷载换算为标准轴载的公式.结果表明:得出的轴载换算公式可充分考虑混凝土基层耐久性沥青路面基层厚度、基层模量、地基模量结构设计参数的影响,具有良好的实用性,可为路面结构设计提供依据.%As a new kind pavement structure, the design method of cement concrete pavement with asphalt surface course in the current specification is not suitable to the durable asphalt pavement with rigid base. Since the characteristics of durable pavement with rigid base are not taken into account, there exists large error in the results getting from the axle-load conversion equation. According to the fatigue equations of popular concrete and lean concrete, the load stress calculation equations rigid base in durable asphalt pavement subjecting standard axle load and different axle-wheel load, and the equivalent fatigue damage principle of concrete base, the axle load conversion equations from the load of single-axle and single-wheel, single-axle and two-wheel and two-axle and two-wheel to the standard axle load are derived. The results show that the axle load conversion equations got in the paper can fully consider the influences of the structure design parameters of base depth, base modulus and subgrade modulus etc. Of durable asphalt pavement with concrete pavement, so the equations have good suitability and can provide basis for pavement structure design.

  8. Dynamic Response of a Rigid Pavement Plate Based on an Inertial Soil.

    Science.gov (United States)

    Gibigaye, Mohamed; Yabi, Crespin Prudence; Alloba, I Ezéchiel

    2016-01-01

    This work presents the dynamic response of a pavement plate resting on a soil whose inertia is taken into account in the design of pavements by rational methods. Thus, the pavement is modeled as a thin plate with finite dimensions, supported longitudinally by dowels and laterally by tie bars. The subgrade is modeled via Pasternak-Vlasov type (three-parameter type) foundation models and the moving traffic load is expressed as a concentrated dynamic load of harmonically varying magnitude, moving straight along the plate with a constant acceleration. The governing equation of the problem is solved using the modified Bolotin method for determining the natural frequencies and the wavenumbers of the system. The orthogonal properties of eigenfunctions are used to find the general solution of the problem. Considering the load over the center of the plate, the results showed that the deflections of the plate are maximum about the middle of the plate but are not null at its edges. It is therefore observed that the deflection decreased 18.33 percent when the inertia of the soil is taken into account. This result shows the possible economic gain when taking into account the inertia of soil in pavement dynamic design. PMID:27382639

  9. Dynamic Response of a Rigid Pavement Plate Based on an Inertial Soil

    Science.gov (United States)

    Gibigaye, Mohamed; Yabi, Crespin Prudence; Alloba, I. Ezéchiel

    2016-01-01

    This work presents the dynamic response of a pavement plate resting on a soil whose inertia is taken into account in the design of pavements by rational methods. Thus, the pavement is modeled as a thin plate with finite dimensions, supported longitudinally by dowels and laterally by tie bars. The subgrade is modeled via Pasternak-Vlasov type (three-parameter type) foundation models and the moving traffic load is expressed as a concentrated dynamic load of harmonically varying magnitude, moving straight along the plate with a constant acceleration. The governing equation of the problem is solved using the modified Bolotin method for determining the natural frequencies and the wavenumbers of the system. The orthogonal properties of eigenfunctions are used to find the general solution of the problem. Considering the load over the center of the plate, the results showed that the deflections of the plate are maximum about the middle of the plate but are not null at its edges. It is therefore observed that the deflection decreased 18.33 percent when the inertia of the soil is taken into account. This result shows the possible economic gain when taking into account the inertia of soil in pavement dynamic design. PMID:27382639

  10. Potential applicability of stress wave velocity method on pavement base materials as a non-destructive testing technique

    Science.gov (United States)

    Mahedi, Masrur

    Aggregates derived from natural sources have been used traditionally as the pavement base materials. But in recent times, the extraction of these natural aggregates has become more labor intensive and costly due to resource depletion and environmental concerns. Thus, the uses of recycled aggregates as the supplementary of natural aggregates are increasing considerably in pavement construction. Use of recycled aggregates such as recycled crushed concrete (RCA) and recycled asphalt pavement (RAP) reduces the rate of natural resource depletion, construction debris and cost. Although recycled aggregates could be used as a viable alternative of conventional base materials, strength characteristics and product variability limit their utility to a great extent. Hence, their applicability is needed to be evaluated extensively based on strength, stiffness and cost factors. But for extensive evaluation, traditionally practiced test methods are proven to be unreasonable in terms of time, cost, reliability and applicability. On the other hand, rapid non-destructive methods have the potential to be less time consuming and inexpensive along with the low variability of test results; therefore improving the reliability of estimated performance of the pavement. In this research work, the experimental program was designed to assess the potential application of stress wave velocity method as a non-destructive test in evaluating recycled base materials. Different combinations of cement treated recycled concrete aggregate (RAP) and recycled crushed concrete (RCA) were used to evaluate the applicability of stress wave velocity method. It was found that, stress wave velocity method is excellent in characterizing the strength and stiffness properties of cement treated base materials. Statistical models, based on P-wave velocity were derived for predicting the modulus of elasticity and compressive strength of different combinations of cement treated RAP, Grade-1 and Grade-2 materials. Two

  11. Simultaneous Multi-vehicle Detection and Tracking Framework with Pavement Constraints Based on Machine Learning and Particle Filter Algorithm

    Institute of Scientific and Technical Information of China (English)

    WANG Ke; HUANG Zhi; ZHONG Zhihua

    2014-01-01

    Due to the large variations of environment with ever-changing background and vehicles with different shapes, colors and appearances, to implement a real-time on-board vehicle recognition system with high adaptability, efficiency and robustness in complicated environments, remains challenging. This paper introduces a simultaneous detection and tracking framework for robust on-board vehicle recognition based on monocular vision technology. The framework utilizes a novel layered machine learning and particle filter to build a multi-vehicle detection and tracking system. In the vehicle detection stage, a layered machine learning method is presented, which combines coarse-search and fine-search to obtain the target using the AdaBoost-based training algorithm. The pavement segmentation method based on characteristic similarity is proposed to estimate the most likely pavement area. Efficiency and accuracy are enhanced by restricting vehicle detection within the downsized area of pavement. In vehicle tracking stage, a multi-objective tracking algorithm based on target state management and particle filter is proposed. The proposed system is evaluated by roadway video captured in a variety of traffics, illumination, and weather conditions. The evaluating results show that, under conditions of proper illumination and clear vehicle appearance, the proposed system achieves 91.2% detection rate and 2.6% false detection rate. Experiments compared to typical algorithms show that, the presented algorithm reduces the false detection rate nearly by half at the cost of decreasing 2.7%–8.6% detection rate. This paper proposes a multi-vehicle detection and tracking system, which is promising for implementation in an on-board vehicle recognition system with high precision, strong robustness and low computational cost.

  12. Influence of mixture composition on the noise and frictional characteristics of flexible pavements

    Science.gov (United States)

    Kowalski, Karol J.

    Both traffic noise and wet pavement-tire friction are mainly affected by the tire/pavement interaction. Existing laboratory test methods allow for evaluation of polishing resistance of the aggregates only. Currently, there is no generally accepted standardized laboratory test method to address noise related issues and the overall frictional properties of pavements (including macrotexture). In this research, which included both laboratory and field components, friction and noise properties of the flexible (asphalt) pavements were investigated. As a part of this study, a laboratory device to polish asphalt specimens was developed and the procedure to evaluate mixture frictional properties was proposed. Following this procedure, forty-six different Superpave mixtures (each utilizing a different aggregate blends), one stone matrix asphalt (SMA) mixture and one porous friction course (PFC) mixture were tested. Six of the above mixes (four Superpave mixtures, SMA mixture and PFC mixture) were selected for laboratory noise testing. This testing was performed using a one-of-a-kind tester called the Tire/Pavement Test Apparatus (TPTA). In addition, the field sections constructed using Superpave, SMA and PFC mixtures were also periodically tested for friction and noise. Field measurements included testing of total of 23 different asphalt and two concrete pavements. The field friction testing was performed using both portable CTM and DFT devices and the (ASTM E 274) locked wheel friction trailer. The laboratory friction testing was performed using CTM and DFT devices only. The results of both field and laboratory friction measurements were used to develop an International Friction Index (IFI)-based frictional requirement for laboratory friction measurements. The results collected in the course of the study indicate that the IFI-based flag values could be successfully used in place of SN-based flag values to characterize frictional characteristics of pavements.

  13. Locating the Drainage Layer for Bituminous Pavements in Indiana

    OpenAIRE

    Hassan, Hossam Farouk.; White, Thomas D.

    1996-01-01

    Pavement subsurface drainage and its effect on pavement performance has been a subject of interest since the 18th and 19th centuries. With no doubt the detrimental effects of heavy wheel loads on pavements with saturated base material is a significant factor. The consequence of subsurface water on pavement performance includes premature rutting, cracking, faulting, and increased roughness, all of which lead to a decrease in serviceability. This research study involves the evaluation of the...

  14. Porous Flame-retarded Asphalt Pavement for Highway Tunnel

    Institute of Scientific and Technical Information of China (English)

    HU Shuguang; HUANG Shaolong; Ding Qingjun

    2008-01-01

    A new way to improve the tunnel fire protection by using flame-retarded porous asphalt pavement containing ATH powders was introduced. Based on the miniature burning test designed and conducted, the burning time and temperature of porous asphalt (PA) and flame-retarded porous asphalt (FRPA) were studied comparing with cement concrete pavement, dense-graded HMA and S MA. Results of burning test and pavement performance test indicate that FRPA is appropriate and suitable as the pavement material of highway tunnel.

  15. Performance of pavements designed with low-cost materials

    Science.gov (United States)

    Grau, R. W.; Yrjanson, W. A.; Packard, R. G.; Barksdale, R. D.; Potts, C. F.; Ruth, B. E.; Smith, L. L.; Huddleston, I. J.; Vinson, T. S.; Hicks, R. G.

    1980-04-01

    The following areas are discussed. Utilization of marginal aggregate materials for secondary road surface layers; econocrete pavements; current practices; construction and performance of sand-asphalt bases and performance of sand-asphalt and limerock pavements in Florida. Cement stabilization of degrading aggregates use of crushed stone screenings in highway construction (abridgement); and sulfur-asphalt pavement technology are also reviewed.

  16. Oral exposure to commercially available coal tar‐based pavement sealcoat induces murine genetic damage and mutations

    Science.gov (United States)

    Watson, Margaret; Arlt, Volker M.; White, Paul A.

    2016-01-01

    Coal tar (CT) is a thick black liquid produced as a by‐product of coal carbonization to produce coke or manufactured gas. It is comprised a complex mixture of polycyclic aromatic compounds, including a wide range of polycyclic aromatic hydrocarbons (PAHs), many of which are genotoxic and carcinogenic. CT is used in some pavement sealants (also known as sealcoat), which are applied to pavement in order to seal and beautify the surface. Human exposure is known to occur not only during application, but also as a result of the weathering process, as elevated levels of PAHs have been found in settled house dust in residences adjacent to CT‐sealed surfaces. In this study we examined the genotoxicity of an extract of a commercially available CT‐based sealcoat in the transgenic Muta™Mouse model. Mice were orally exposed to 3 doses of sealcoat extract daily for 28 days. We evaluated genotoxicity by examining: (1) stable DNA adducts and (2) lacZ mutations in bone marrow, liver, lung, small intestine, and glandular stomach, as well as (3) micronucleated red blood cells. Significant increases were seen for each endpoint and in all tissues. The potency of the response differed across tissues, with the highest frequency of adducts occurring in liver and lung, and the highest frequency of mutations occurring in small intestine. The results of this study are the first demonstration of mammalian genotoxicity following exposure to CT‐containing pavement sealcoat. This work provides in vivo evidence to support the contention that there may be adverse health effects in mammals, and potentially in humans, from exposure to coal tar. Environ. Mol. Mutagen. 57:535–545, 2016. © 2016 Her Majesty the Queen in Right of Canada PMID:27473530

  17. Oral exposure to commercially available coal tar-based pavement sealcoat induces murine genetic damage and mutations.

    Science.gov (United States)

    Long, Alexandra S; Watson, Margaret; Arlt, Volker M; White, Paul A

    2016-08-01

    Coal tar (CT) is a thick black liquid produced as a by-product of coal carbonization to produce coke or manufactured gas. It is comprised a complex mixture of polycyclic aromatic compounds, including a wide range of polycyclic aromatic hydrocarbons (PAHs), many of which are genotoxic and carcinogenic. CT is used in some pavement sealants (also known as sealcoat), which are applied to pavement in order to seal and beautify the surface. Human exposure is known to occur not only during application, but also as a result of the weathering process, as elevated levels of PAHs have been found in settled house dust in residences adjacent to CT-sealed surfaces. In this study we examined the genotoxicity of an extract of a commercially available CT-based sealcoat in the transgenic Muta™Mouse model. Mice were orally exposed to 3 doses of sealcoat extract daily for 28 days. We evaluated genotoxicity by examining: (1) stable DNA adducts and (2) lacZ mutations in bone marrow, liver, lung, small intestine, and glandular stomach, as well as (3) micronucleated red blood cells. Significant increases were seen for each endpoint and in all tissues. The potency of the response differed across tissues, with the highest frequency of adducts occurring in liver and lung, and the highest frequency of mutations occurring in small intestine. The results of this study are the first demonstration of mammalian genotoxicity following exposure to CT-containing pavement sealcoat. This work provides in vivo evidence to support the contention that there may be adverse health effects in mammals, and potentially in humans, from exposure to coal tar. Environ. Mol. Mutagen. 57:535-545, 2016. © 2016 Her Majesty the Queen in Right of Canada. PMID:27473530

  18. PAH Concentrations Decline Following 2006 Ban on Coal-Tar-Based Pavement Sealants in Austin, Texas

    Science.gov (United States)

    Van Metre, P. C.; Mahler, B. J.

    2013-12-01

    Recent studies have concluded that coal-tar-based pavement sealants (CT sealants) are a major source of polycyclic aromatic hydrocarbons (PAHs) in non-industrial urban settings in the United States. In 2006, Austin, TX, became the first jurisdiction in the U.S. to ban the use of CT sealants. We evaluated PAH concentrations following the ban by analyzing sediment cores collected from Lady Bird Lake in 2012; Lady Bird Lake impounds the Colorado River in central Austin and receives runoff from much of the greater Austin area. The mean sum concentration of the 16 U.S. Environmental Protection Agency Priority Pollutant PAHs (∑PAH16) in one of two 2012 sediment cores analyzed for PAHs declined 75% from before 2006 (mean of 4 samples=8,090 μg kg-1) to 2012 (mean of 2 samples=2,030 μg kg-1), reversing a 40-year (1959-1999) upward trend in PAH concentrations that was previously documented. The downward trend in PAH concentrations in the seven uppermost 1 cm sampling intervals in the first 2012 core was statistically significant (r=0.93, p-value=0.002). Post-2008 PAH trends in the second 2012 core were similar (significant downward trend in the six uppermost 1 cm sampling intervals and mean 2012 ∑PAH16 of 2,390 μg kg-1); however, pre-2007 sediment did not appear to have been preserved in this core likely because of the effects of flooding on sediment deposition and mixing at this site--the largest flood on the Colorado River in Austin in 20 years was in 2007. On the basis of a comparison of lake-sediment PAH profiles to 22 PAH source profiles, the PAH loading to lake sediment continues to be dominated by CT sealants. The continued dominance of proportional PAH loading by CT sealants in spite of decreased concentrations since 2006 might be because legacy CT sealant and contaminated soils and sediments continue to yield PAHs to runoff. A previous study using source-receptor modeling concluded that CT sealants were the largest PAH source to 40 urban lakes studied in the

  19. Comportamiento de una pista experimental de pavimento flexible con base estabilizada con cal Behavior of an experimental track of flexible pavement with lime stabilized base

    Directory of Open Access Journals (Sweden)

    César Augusto Hidalgo Montoya

    2010-01-01

    Full Text Available En este trabajo se presentan resultados de una investigación realizada para determinar las propiedades de deformabilidad de bases estabilizadas con cal a partir de ensayos de campo no destructivos. Se realizaron ensayos de placa estática y viga Benkelman en un tramo de prueba de pavimento flexible de 70m de longitud. Se usaron diferentes mezclas de suelo-cal y varios espesores de la estructura para evaluar el comportamiento del pavimento. A partir de los resultados de estos ensayos fueron realizados retroanálisis del comportamiento del pavimento. El método de los elementos finitos y el modelo elástico de esfuerzos y deformaciones en sistema de capas múltiples se usaron en los retroanálisis para estimar los módulos de deformabilidad de la base estabilizada con cal. Se concluye que la adición de cal mejora sustancialmente las propiedades de los pavimentos evaluados.This paper presents results of a research carried out to determine the proprieties of deformation of lime stabilized bases using non destructive field tests. Static plate tests and Benkelman beam tests were made on an experimental track of flexible pavement of 70 m length. Several mixtures of soil-lime and several thickness of the stabilized base were used to evaluate the behavior of the pavement. With the results of these tests, back analysis of the behavior of pavement was carried out. The finite elements method and the elastic stress and strain in a multi layers system were used to estimate the deformation modulus of the lime stabilized bases. It is concluded that the lime addition significantly improves the properties of evaluated pavements.

  20. Pavement Subgrade Performance Study

    DEFF Research Database (Denmark)

    Zhang, Wei; Ullidtz, Per; Macdonald, Robin

    1998-01-01

    The report describes the second test in the Danish Road Testing Machine (RTM) under the International Pavement Subgrade Performance Study. Pavement response was measured in different layers, and compared to different theroretical values. Performance in terms of plastic strains, rutting...

  1. Sampling optimization for high-speed weigh-in-motion measurements using in-pavement strain-based sensors

    International Nuclear Information System (INIS)

    Weigh-in-motion (WIM) measurement has been widely used for weight enforcement, pavement design, freight management, and intelligent transportation systems to monitor traffic in real-time. However, to use such sensors effectively, vehicles must exit the traffic stream and slow down to match their current capabilities. Hence, agencies need devices with higher vehicle passing speed capabilities to enable continuous weight measurements at mainline speeds. The current practices for data acquisition at such high speeds are fragmented. Deployment configurations and settings depend mainly on the experiences of operation engineers. To assure adequate data, most practitioners use very high frequency measurements that result in redundant samples, thereby diminishing the potential for real-time processing. The larger data memory requirements from higher sample rates also increase storage and processing costs. The field lacks a sampling design or standard to guide appropriate data acquisition of high-speed WIM measurements. This study develops the appropriate sample rate requirements as a function of the vehicle speed. Simulations and field experiments validate the methods developed. The results will serve as guidelines for future high-speed WIM measurements using in-pavement strain-based sensors. (paper)

  2. Analysis and design optimization of flexible pavement

    Energy Technology Data Exchange (ETDEWEB)

    Mamlouk, M.S.; Zaniewski, J.P.; He, W.

    2000-04-01

    A project-level optimization approach was developed to minimize total pavement cost within an analysis period. Using this approach, the designer is able to select the optimum initial pavement thickness, overlay thickness, and overlay timing. The model in this approach is capable of predicting both pavement performance and condition in terms of roughness, fatigue cracking, and rutting. The developed model combines the American Association of State Highway and Transportation Officials (AASHTO) design procedure and the mechanistic multilayer elastic solution. The Optimization for Pavement Analysis (OPA) computer program was developed using the prescribed approach. The OPA program incorporates the AASHTO equations, the multilayer elastic system ELSYM5 model, and the nonlinear dynamic programming optimization technique. The program is PC-based and can run in either a Windows 3.1 or a Windows 95 environment. Using the OPA program, a typical pavement section was analyzed under different traffic volumes and material properties. The optimum design strategy that produces the minimum total pavement cost in each case was determined. The initial construction cost, overlay cost, highway user cost, and total pavement cost were also calculated. The methodology developed during this research should lead to more cost-effective pavements for agencies adopting the recommended analysis methods.

  3. Pavement Crack Detection Using Spectral Clustering Method

    Directory of Open Access Journals (Sweden)

    Jin Huazhong

    2015-01-01

    Full Text Available Pavement crack detection plays an important role in pavement maintaining and management, nowadays, which could be performed through remote image analysis. Thus, edges of pavement crack should be extracted in advance; in general, traditional edge detection methods don’t consider phase information and the spatial relationship between the adjacent image areas to extract the edges. To overcome the deficiency of the traditional approaches, this paper proposes a pavement crack detection algorithm based on spectral clustering method. Firstly, a measure of similarity between pairs of pixels is taken into account through orientation energy. Then, spatial relationship is needed to find regions where similarity between pixels in a given region is high and similarity between pixels in different regions is low. After that, crack edge detection is completed with spectral clustering method. The presented method has been run on some real life images of pavement crack, experimental results display that the crack detection method of this paper could obtain ideal result.

  4. Stabilization of Black Cotton Soil With Sand and Cement as a Subgrade for Pavement

    OpenAIRE

    Mrs. Neetu B. Ramteke *1 ,; Prof. Anilkumar Saxena 2 ,; , Prof. T. R. Arora 3

    2014-01-01

    Expansive soil (Black cotton soil) is very weak and does not have enough stability for any type of construction work. In pavement, subgrade layer is the bottommost layer underlying the base course or surface course. To make the subgrade soil stable, by improving its engineering properties is very essential. In the present work, stabilization of subgrade soil by using sand and cement (varying percentage of sand and constant percentage of cement by weight of soil) is used to enh...

  5. Strain transfer analysis of optical fiber based sensors embedded in an asphalt pavement structure

    Science.gov (United States)

    Wang, Huaping; Xiang, Ping

    2016-07-01

    Asphalt pavement is vulnerable to random damage, such as cracking and rutting, which can be proactively identified by distributed optical fiber sensing technology. However, due to the material nature of optical fibers, a bare fiber is apt to be damaged during the construction process of pavements. Thus, a protective layer is needed for this application. Unfortunately, part of the strain of the host material is absorbed by the protective layer when transferring the strain to the sensing fiber. To account for the strain transfer error, in this paper a theoretical analysis of the strain transfer of a three-layered general model has been carried out by introducing Goodman’s hypothesis to describe the interfacial shear stress relationship. The model considers the viscoelastic behavior of the host material and protective layer. The effects of one crack in the host material and the sensing length on strain transfer relationship are been discussed. To validate the effectiveness of the strain transfer analysis, a flexible asphalt-mastic packaged distributed optical fiber sensor was designed and tested in a laboratory environment to monitor the distributed strain and appearance of cracks in an asphalt concrete beam at two different temperatures. The experimental results indicated that the developed strain transfer formula can significantly reduce the strain transfer error, and that the asphalt-mastic packaged optical fiber sensor can successfully monitor the distributed strain and identify local cracks.

  6. Evaluation of Permeability of Asphalt Pavement Based on Differential Thermal Infrared of Pavement Surface%基于路表红外差热的沥青混凝土路面渗水性能评价

    Institute of Scientific and Technical Information of China (English)

    李志栋; 黄晓明; 赵洁雯; 郭辉; 许涛; 陈广秀

    2012-01-01

    因离析、荷载、自然等因素的影响,沥青混凝土路面产生密实性不均一以及渗水性能表面差异性,为了改变目前渗水仪检测效率低、代表性差等现状,能够快速、多剖面对其渗水性能进行检测评价.首先,通过试验与有限元方法分析了沥青混凝土路面表面温度及其差异度与其渗水性能的相关性;同时,优选了路表温度差异度的最佳检测方法.研究表明:路表温度差异度与渗水性能相关系数达到0.9747,与传统渗水仪的渗水系数相关性达0.8272,建立了通过红外识别路表温度差异度来检测沥青混凝土路面渗水性能的方法和相应评价标准.另外,开发了连续测速达100 km/h的沥青混凝土路面渗水性红外检测仪,与传统渗水仪相比,检测范围由点变面,效率提高80倍,费用节约58%,并与处治透水的雾封层技术实现数据信息共享.%Because of synthesis effect of the segregation, loads and climate, the densification and permeability of the surface of asphalt concrete pavement is different. To change the status that the detecting efficiency and veracity of permeability detector at present is low and the permeability can be detected quickly and multi-section,firstly, the relativity between the surface temperature difference degree and permeability of asphalt concrete pavement is analyzed by the laboratory experiments and ABAQUS elements, and the detecting way of temperature difference degree optimized. It proved that relativity of the surface temperature difference degree and permeability of asphalt concrete pavement or permeability coefficient by the permeability detector arrived to 0. 974 7 or 0. 827 2, and detecting way of asphalt concrete pavement permeability is established based on the surface temperature difference degree identified by the infrared technology. At the same time, based on this principle the first continuous infrared detector reached l00km/h ,of asphalt concrete pavement

  7. Experimental Analysis on Semi-rigid Base Pavement Performance Improvement%半刚性基层路面性能改良试验分析

    Institute of Scientific and Technical Information of China (English)

    张敏; 党玲博; 罗阳明

    2011-01-01

    Cement-lime-clay base is commonly used for asphalt pavement in southern Henan area.In order to improve pavement performance,this paper studies the influence of fiber on semi-rigid base pavement performance through test.Through comparison from various tests,it is shown that pavement splitting strength can be improved with the proportion of cement,lime and clay of 642664 and mixed with 0.05 % polypropylene fiber.%河南南部地区沥青路面常用水泥石灰河砂土基层。为了改进其路用性能,通过试验,研究了添加纤维丝对改善半刚性基层路面性能的影响,并对多组不同的试验比较分析,得到在水泥石灰粘土河砂=6:4:26:64的基础上,摻0.05%聚丙烯纤维,能提高其劈裂强度。

  8. Mechanical Properties of Asphalt Pavement Structure in Highway Tunnel

    Institute of Scientific and Technical Information of China (English)

    SHI Chun-xiang; GUO Zhong-yin

    2008-01-01

    A linear full 3D finite element method (FEM) was performed in order to present the key design parameters of highway tunnel asphalt pavement under double-wheel load on rectangular loaded area considering horizontal contact stress induced by the acceleration/deceleration of vehicles. The key design parameters are the maximum horizontal tensile stresses at the surface of the asphalt layer, the maximum horizontal tensile stresses at the bottom of the asphalt layer and the maximum vertical shear stresses at the surface of the as- phalt layer were calculated. The influencing factors such as double-wheel weight; asphalt layer thickness; base course stiffness modulus and thickness; and the contact conditions among the structure layers on these key design parameters were also examined separately to propose construction procedures of highway tunnel asphalt pavement.

  9. Network-based Database Course

    DEFF Research Database (Denmark)

    Nielsen, J.N.; Knudsen, Morten; Nielsen, Jens Frederik Dalsgaard;

    A course in database design and implementation has been de- signed, utilizing existing network facilities. The course is an elementary course for students of computer engineering. Its purpose is to give the students a theoretical database knowledge as well as practical experience with design...... and implementation. A tutorial relational database and the students self-designed databases are implemented on the UNIX system of Aalborg University, thus giving the teacher the possibility of live demonstrations in the lecture room, and the students the possibility of interactive learning in their working rooms...

  10. Mechanistic design concepts for conventional flexible pavements

    Science.gov (United States)

    Elliott, R. P.; Thompson, M. R.

    1985-02-01

    Mechanical design concepts for convetional flexible pavement (asphalt concrete (AC) surface plus granular base/subbase) for highways are proposed and validated. The procedure is based on ILLI-PAVE, a stress dependent finite element computer program, coupled with appropriate transfer functions. Two design criteria are considered: AC flexural fatigue cracking and subgrade rutting. Algorithms were developed relating pavement response parameters (stresses, strains, deflections) to AC thickness, AC moduli, granular layer thickness, and subgrade moduli. Extensive analyses of the AASHO Road Test flexible pavement data are presented supporting the validity of the proposed concepts.

  11. Concentrations of Polycyclic Aromatic Hydrocarbons (PAHs) and Azaarenes in Runoff from Freshly Applied Coal-Tar-Based Pavement Sealcoat

    Science.gov (United States)

    Mahler, B. J.; Van Metre, P. C.

    2013-12-01

    Coal-tar-based sealcoat (CT-sealcoat) is extensively applied to asphalt parking lots and driveways in the U.S. and Canada. Toxicity to fish and invertebrates of runoff from pavement to which CT-sealcoat has been freshly applied has been reported, but relatively little is known about how concentrations of chemicals in runoff change in the hours to days following sealcoat application. We measured the concentrations of 16 U.S. Environmental Protection Agency Priority Pollutant polycyclic aromatic hydrocarbons (PAHs) and 7 azaarenes in 9 samples of simulated runoff from a coal-tar-sealed test plot collected at increasing intervals from 5 hours to 16 weeks following application. Azaarenes, several of which are common constituents in coal-tar pitch, and their oxidized derivatives, azaarones, are an emerging group of little-studied heterocyclic chemicals. Runoff samples were collected by spraying 25 L of a diluted groundwater to 10 m2 on sealed pavement and retrieving the runoff downgradient where the runoff pooled against spill berms. Unfiltered samples were analyzed by GC/MS following liquid-liquid extraction. In the first sample (t=5 hr), phenanthrene had the highest concentration (130 μg/L) among the 16 PAHs. Concentrations of the lower molecular weight (LMW) PAHs (2 and 3 ring) decreased during the 16 weeks following application, and concentrations of the higher molecular weight (HMW) PAHs (4 to 6 ring) increased, coincident with an increase in the concentration of suspended particulates. In the final sample (t=16 weeks), fluoranthene had the highest concentration (36 μg/L) among the 16 PAHs. Of the azaarenes measured, concentrations of acridine and carbazole (107 and 750 μg/L, respectively) in the initial sample exceeded those of any of the PAHs measured except phenanthrene; acridine and carbazole concentrations decreased over the 5 weeks to <5% of their initial values. Samples of dried sealcoat were analyzed the day of application and 5 weeks later. Samples were

  12. Thermal stability analysis under embankment with asphalt pavement and cement pavement in permafrost regions.

    Science.gov (United States)

    Junwei, Zhang; Jinping, Li; Xiaojuan, Quan

    2013-01-01

    The permafrost degradation is the fundamental cause generating embankment diseases and pavement diseases in permafrost region while the permafrost degradation is related with temperature. Based on the field monitoring results of ground temperature along G214 Highway in high temperature permafrost regions, both the ground temperatures in superficial layer and the annual average temperatures under the embankment were discussed, respectively, for concrete pavements and asphalt pavements. The maximum depth of temperature field under the embankment for concrete pavements and asphalt pavements was also studied by using the finite element method. The results of numerical analysis indicate that there were remarkable seasonal differences of the ground temperatures in superficial layer between asphalt pavement and concrete pavement. The maximum influencing depth of temperature field under the permafrost embankment for every pavement was under the depth of 8 m. The thawed cores under both embankments have close relation with the maximum thawed depth, the embankment height, and the service time. The effective measurements will be proposed to keep the thermal stabilities of highway embankment by the results. PMID:24027444

  13. Pavement Testing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Comprehensive Environmental and Structural Analyses The ERDC Pavement Testing Facility, located on the ERDC Vicksburg campus, was originally constructed to provide...

  14. A study of bituminous pavements to determine a correlation between pavement structure designs and tripping of asphalt cement

    Science.gov (United States)

    Barton, B. R.

    1984-03-01

    After detecting a few cases of stripping of asphalt cement from the aggregate in bituminous pavement, there was concern that stripping might be a widespread problem in the state. It is agreed that water is the cause of stripping, and it was the opinion of some that pavements on granular bases would be less likely to strip because of supposedly better drainage characteristics. Differently designed pavement structures in all areas of the state were investigated to determine if there is a correlation between base and pavement design and stripping. Stripping was not as widespread as had been feared and there was less stripping in fulldepth bituminous base and pavement constructed over a lime-treated subgrade than in pavements constructed oer granular bases. This was contrary to what some had theorized.

  15. Assessment of highway pavements using GPR

    Science.gov (United States)

    Plati, Christina; Loizos, Andreas

    2015-04-01

    Highway infrastructure is a prerequisite for a functioning economy and social life. Highways, often prone to congestion and disruption, are one of the aspects of a modern transport network that require maximum efficiency if an integrated transport network, and sustainable mobility, is to be achieved. Assessing the condition of highway structures, to plan subsequent maintenance, is essential to allow the long-term functioning of a road network. Optimizing the methods used for such assessment will lead to better information being obtained about the road and underlying ground conditions. The condition of highway structures will be affected by a number of factors, including the properties of the highway pavement, the supporting sub-base and the subgrade (natural ground), and the ability to obtain good information about the entire road structure, from pavement to subgrade, allows appropriate maintenance programs to be planned. The maintenance of highway pavements causes considerable cost and in many cases obstruction to traffic flow. In this situation, methods that provide information on the present condition of pavement structure non-destructively and economically are of great interest. It has been shown that Ground-Penetrating-Radar (GPR), which is a Non Destructive Technique (NDT), can deliver information that is useful for the planning of pavement maintenance activities. More specifically GPR is used by pavement engineers in order to determine physical properties and characteristics of the pavement structure, information that is valuable for the assessment of pavement condition. This work gives an overview on the practical application of GPR using examples from highway asphalt pavements monitoring. The presented individual applications of GPR pavement diagnostics concern structure homogeneity, thickness of pavement layers, dielectric properties of asphalt materials etc. It is worthwhile mentioning that a number of applications are standard procedures, either

  16. EVALUATION OF RUTTING DEPTH IN FLEXIBLE PAVEMENTS BY USING FINITE ELEMENT ANALYSIS AND LOCAL EMPIRICAL MODEL

    Directory of Open Access Journals (Sweden)

    Alaa H. Abed

    2012-01-01

    Full Text Available The objective of this research is to predict rut depth in local flexible pavements. Predication model in pavement performance is the process that used to estimate the parameter values which related to pavement structure, environmental condition and traffic loading. The different local empirical models have been used to calculate permanent deformation which include environmental and traffic conditions. Finite element analysis through ANSYS computer software is used to analyze two dimensional linear elastic plane strain problem through (Plane 82 elements. Standard Axle Load (ESAL of 18 kip (80 kN loading on an axle with dual set of tires, the wheel spacing is 13.5 in (343 mm with tire contact pressure of 87 psi (0.6 MPa is used. The pavement system is assumed to be an elastic multi-layers system with each layer being isotropic, homogeneous with specified resilient modulus and Poisson ratio. Each layer is to extend to infinity in the horizontal direction and have a finite thickness except the bottom layer. The analysis of results show that, although, the stress level decrease 14% in the leveling course and 27% in the base course, the rut depth is increased by 12 and 28% in that layers respectively because the material properties is changed.

  17. MODELING PAVEMENT DETERIORATION PROCESSES BY POISSON HIDDEN MARKOV MODELS

    Science.gov (United States)

    Nam, Le Thanh; Kaito, Kiyoyuki; Kobayashi, Kiyoshi; Okizuka, Ryosuke

    In pavement management, it is important to estimate lifecycle cost, which is composed of the expenses for repairing local damages, including potholes, and repairing and rehabilitating the surface and base layers of pavements, including overlays. In this study, a model is produced under the assumption that the deterioration process of pavement is a complex one that includes local damages, which occur frequently, and the deterioration of the surface and base layers of pavement, which progresses slowly. The variation in pavement soundness is expressed by the Markov deterioration model and the Poisson hidden Markov deterioration model, in which the frequency of local damage depends on the distribution of pavement soundness, is formulated. In addition, the authors suggest a model estimation method using the Markov Chain Monte Carlo (MCMC) method, and attempt to demonstrate the applicability of the proposed Poisson hidden Markov deterioration model by studying concrete application cases.

  18. Permanent Deformation Computation Research of Graded Gravel Base in Flexible Pavement%柔性路面粒料层的永久变形计算

    Institute of Scientific and Technical Information of China (English)

    王修山; 丁小军; 谢永利

    2011-01-01

    基于重复动三轴试验结果,运用Kenlayer程序计算和lstopt统计分析软件进行非线性回归拟合,建立了一种在车辆重复轴栽作用下的柔性路面粒料层永久变形量计算方法,并引入现场修正系数对室内永久变形量预估模型进行修正.结果表明,柔性路面粒料层的永久变形量可通过所提出的回归方程直接计算,并可将其用于中国沥青路面车辙预估.%Based on repeatedly dynamic triaxial test result fitting, using the Kenlayer computational procedure and the 1stopt statistical analysis software, the nonlinear regression and fitting were carried out. One permanent deformation computational method of flexible pavement graded gravel base under the vehicles axle load repeatedly function was established. A scene correction coefficient was introduced to modify the indoor permanent deformation estimate model. The permanent deformation of flexible pavement graded gravel base may be directly calculated through the regression formula proposed in this article. And it can be used to forecast Chinese asphalt pavement rutting.

  19. Performance of Drained and Undrained Flexible Pavement Structures Under Wet Conditions Test Data From Accelerated Pavement Test Section 543-Drained

    OpenAIRE

    Harvey, John; Bejarano, Manuel O.; Ali, Abdikarim; Russo, Mark; Mahama, David; Hung, Dave; Preedonant, Pitipat

    2004-01-01

    This report is the first in a series of four reports that describe the results of accelerated pavement tests on full-scale pavements with “wet†base conditions at the Pavement Research Center, located at the University of California Berkeley Richmond Field Station (RFS). The report contains a summary of the results and associated analysis of a pavement section comprised of three lifts of asphalt concrete, an asphalt treated permeable base (ATPB) layer, and untreated aggregate base layers o...

  20. Study on Asphalt Pavement Mechanical Model Based on Calibration of Measurement%基于实测验证的沥青路面力学模型研究

    Institute of Scientific and Technical Information of China (English)

    白琦峰; 钱振东; 吴春颖

    2011-01-01

    The data of temperature and strain of asphalt pavement were measured. Based on comparing the calculated strains and pavement mechanical models, the pavement mechanical model and parameters which can agree with the actual pavement more closely was studied. Furthermore, the interface continuity conditions of different types of pavement and the amendment method of calculated pavement mechanical parameters was studied. It is found that (1) multi-layer elastic model using dynamic modulus is the better choice for pavement mechanical analysis; (2) as for the layers interface continuity condition, flexible pavement and combined base pavement are continuous, however semi-rigid base pavement is semi-continuous with friction coefficient of 0.65 ~ 0.75. The amendment method of calculated pavement mechanical parameters was proposed, and the correlation coefficient between the measured and the calculated values is about 0.9 accordingly.%实测不同路面结构温度、应变数据,与不同路面力学模型、参数的计算结果对比,研究与路面实际受力更为相符的力学模型和材料力学参数.对不同路面结构的层间连续状态进行分析,并研究了路面力学指标计算结果的修正方案.结果表明:基于动态模量的弹性层状体系更适于路面力学分析;力学模型中柔性路面、组合式基层沥青路面层间状态可假设为连续,半刚性基层与沥青面层间合适的摩擦系数为0.65~0.75;提出了力学理论计算指标向实测结果修正的方法,按此修正,不同路面结构的力学分析结果与实测结果的相关系数可达到0.9.

  1. Layered pavement systems

    Science.gov (United States)

    Numerous aspects of the mechanical and structural response of layered pavement systems are discussed. Subgrade moduli for soil that exhibits nonlinear behavior are predicted. The use of a pressure meter test to predict modulus is discussed. Load equivalency factors of triaxial loading for flexible pavements is discussed, as well as a constitutive equation for the permanent strain of sand subjected to cyclic loading.

  2. Asphalt in Pavement Maintenance.

    Science.gov (United States)

    Asphalt Inst., College Park, MD.

    Maintenance methods that can be used equally well in all regions of the country have been developed for the use of asphalt in pavement maintenance. Specific information covering methods, equipment and terminology that applies to the use of asphalt in the maintenance of all types of pavement structures, including shoulders, is provided. In many…

  3. Experimental Study of Recycling of Waste Concrete Cement Pavement in Semi-rigid Base Course%废弃水泥混凝土道面在路面半刚性基层中再生利用的试验研究

    Institute of Scientific and Technical Information of China (English)

    单双成; 陈满

    2013-01-01

    It is an important problem to make effective use of scrap concrete material during maintenance or reconstruction of a cement concrete road.By studying the waste concrete crushed and screened some results were obtained that the recycled aggregate contained water of crystallization which would affect the optimal amount of water and the determination of the maximum dry density.Recycled coarse aggregate and natural gravel had quite mechanical properties.Cement stabilized recycled mixtures' design were did and performance tests found that cement stabilized recycled aggregate has good strength,frost resistance,water stability.It had similar resilient modulus with cement stabilized natural aggregate and poor performance anti-shrinkage deformation.Control regeneration mixing amount of fine aggregate can be very good to meet the requirements of the semi-rigid base material.%水泥混凝土道路改建时形成的废弃混凝土块的有效利用是一个亟待解决的问题.通过对破碎、筛分后的废弃混凝土性能研究发现:再生料中含有部分结晶水,会影响最佳用水量和最大干密度的确定;再生粗集料和天然碎石具有相当的力学性能.对水泥稳定再生集料进行了配合比设计,并通过性能测试发现:水泥稳定再生集料具有较好的强度,抗冻性能,水稳定性能;和水稳天然集料的抗压回弹模量相当;抗收缩变形性能较差.控制再生细集料掺加量可以非常好的满足半刚性基层材料的要求.

  4. Precast concrete pavements

    Science.gov (United States)

    Rollings, R. S.; Chou, Y. T.

    1981-11-01

    This report reviewed published literature on precast concrete pavements and found that precast concrete pavements have had some limited application in airfields, roads, and storage areas. This review of past experience and an analytical study of precast slabs concluded that existing design and construction techniques can be adapted for use with precast concrete pavements, but more work is needed to develop effective and easily constructed load transfer designs for slab joints. Precast concrete does not offer any advantage for conventional pavements due to its high cost and surface roughness, but it may find applications for special problems such as construction in adverse weather, subgrade settlement, temporary pavements that need to be relocated, and military operations.

  5. “路基路面工程”课程教学改革与探讨%Reform and Study of the Problems in the Course Teaching of Subgrade and Pavement Engineering

    Institute of Scientific and Technical Information of China (English)

    张瑛

    2012-01-01

    As for the problems existing in teaching the course of Subgrade and Pavement Engineering, this paper discusses the innovation of teaching content and method, which stresses the characters of engineering nature, and the equal importance of both theoretical and practical teaching.%针对目前"路基路面工程"课程教学中存在的若干问题,对课程教学内容和教学方法的改革进行了相关探讨,突出了"路基路面工程"课程理论教学与实践教学并重、工程性强的特点。

  6. Numerical Investigation of Design Strategies to Achieve Long-Life Pavements

    CERN Document Server

    Ghauch, Ziad G

    2011-01-01

    Increasing the HMA base thickness and modifying the HMA mixture properties to improve the resistance to fatigue cracking are among the most popular methods for achieving long-lasting pavements. Such methods are based on the idea of reducing the tensile strain at the bottom of the HMA layer below the Fatigue Endurance Limit (FEL), a level of strain below which no cumulative damage occurs to the HMA mixture. This study investigates the effectiveness of several design strategies involved in long-life, perpetual pavement design. A 3D Finite Element model of the pavement involving a linear viscoelastic constitutive model for HMA materials and non-uniform tire contact stresses is developed using ABAQUS 6.11. The effects of asphalt base course thickness and mixture type, rich binder layer, and aggregate subbase layer are examined. Four asphalt base course mixture types, namely dense graded, polymer modified, high modulus, and standard binder, are studied as a function of the asphalt base course thickness. The result...

  7. Study on Flexible Pavement Failures in Soft Soil Tropical Regions

    Science.gov (United States)

    Jayakumar, M.; Chee Soon, Lee

    2015-04-01

    Road network system experienced rapid upgrowth since ages ago and it started developing in Malaysia during the colonization of British due to its significant impacts in transportation field. Flexible pavement, the major road network in Malaysia, has been deteriorating by various types of distresses which cause descending serviceability of the pavement structure. This paper discusses the pavement condition assessment carried out in Sarawak and Sabah, Malaysia to have design solutions for flexible pavement failures. Field tests were conducted to examine the subgrade strength of existing roads in Sarawak at various failure locations, to assess the impact of subgrade strength on pavement failures. Research outcomes from field condition assessment and subgrade testing showed that the critical causes of pavement failures are inadequate design and maintenance of drainage system and shoulder cross fall, along with inadequate pavement thickness provided by may be assuming the conservative value of soil strength at optimum moisture content, whereas the exiting and expected subgrade strengths at equilibrium moisture content are far below. Our further research shows that stabilized existing recycled asphalt and base materials to use as a sub-base along with bitumen stabilized open graded base in the pavement composition may be a viable solution for pavement failures.

  8. Analysis of Mechanical Response of Wheel Load on Semi -rigid Base Asphalt Pavement Structure%车轮荷载对半刚性基层沥青路面结构的力学响应分析

    Institute of Scientific and Technical Information of China (English)

    徐伟杰

    2012-01-01

    Based on the theory and standards of the asphalt pavement design, typical semi - rigid asphalt pavement structure and material parameters were chosen. To calculate the stress, strain, displacement of the pavement structure under different loads BISAR3.0 software was adopted and analyzed the impact of the mechanical indicator on the pavement structure. The results show that the impact of different load patterns on the pavement structure is quite large, which can provide a useful reference for further explaining the pavement damage phenomenon of the%基于我国的沥青路面设计理论及标准,选取典型半刚性基层路面结构及材料参数,采用BISAR3.0软件对不同荷载作用下的路面结构应力、应变和位移进行计算,并分析了各力学指标对道路结构的影响。结果显示:不同荷载模式对路面结构的影响相当大,这对进一步解释路面面层的一些破坏现象提供了有益的参考。

  9. 刚柔复合式路面沥青面层动态应变试验研究%Experimental Study on Dynamic Strain of Asphalt Surface Course of Rigid-flexible Composite Pavement Structure

    Institute of Scientific and Technical Information of China (English)

    刘志胜; 赵娟娟

    2016-01-01

    为深入研究刚柔复合式路面沥青面层车辙病害机理,采用复合路面结构车辙试验模拟路面荷载动态作用,借助光纤光栅应变检测技术测试不同方向、不同荷载、不同类型混合料和不同温度下沥青混合料的动态应变,从荷载大小、混合料类型和温度3个方面分析复合式路面沥青面层车辙变形特征.结果表明:动态荷载作用下刚柔复合式路面沥青面层的横向应变小于纵向应变,荷载消除后横向应变可恢复60%,而纵向应变仅可恢复20%;一定范围内沥青混合料动态应变与荷载大小成正线性关系,应变的恢复能力与荷载大小成反向线性关系;SMA的应变比AC小12%,而变形恢复能力高出约60%;高温环境下,荷载间接作用也会引起沥青混合料的应变,SMA的抗变形能力明显高于AC沥青混合料.%For further research into rut disease mechanism of asphalt surface course of rigid-flexible composite pavement,wheel rutting test was used to simulate dynamic load on pavement.The dynamic strain of asphalt mixture of different types under different temperature,under different loads in sizes and directions were measured by use of optical fiber testing technology to analyze the characters of wheel rutting deformation of asphalt surface course in composite pavement from the three aspects of load size,mixture types and the temperature.The result showed that under dynamic loading,the cross strain of the asphalt surface course of the rigid-flexible composite pavement is less than the longitudinal strain.After removal of load,the cross strain can recover by 60% while the longitudinal strain can recover only by 20%.Within given range there exists a positive linear relationship between the dynamic strain of asphalt mixture and load size while a reverse directional linear relationship between strain recovering ability and load size.SMA is of 12% less dynamic strain than AC and of 60% higher recovering ability

  10. 基于价值流图的高速公路路面施工管理%Pavement Construction Management Based on Value Stream Map

    Institute of Scientific and Technical Information of China (English)

    张连营; 刘婧; 李彦伟

    2015-01-01

    To improve the reliability and stability of the pavement construction process,this research implemented improvements based on the value stream map(VSM). Firstly,through the field data collection,this research drew the current-state map of the pavement construction. We diagnosed incompact construction process,unstable production rhythm,construction delay and quality defect via analyzing the current-state map. Aiming at above problems,this research proposed five improvement measures from three aspects:construction team,process flow and project site. Comparing with the future-state map of the pavement construction,the schedule,quality and occupational health and safety(OHS)of the pavement construction process has significantly increased. This research of pavement construction management based on VSM provides case studying reference and theory support for the lean construction.%为提高高速公路路面施工流程的可靠性和稳定性,基于价值流图进行施工管理改进。通过收集现场数据,绘制路面施工的现状价值流图。分析发现施工过程中存在工序不紧凑、生产节拍不稳定、工期拖延和质量缺陷等施工管理问题。针对这些问题,从施工团队、工序流程和项目现场三方面提出了改进措施。通过与路面施工未来价值流图的对比,精益改进的实施使公路路面施工流程在工期、质量和职业健康安全指标上得到显著提升,为公路项目的精益管理提供了实际案例借鉴和理论方法支持。

  11. Hybrid green permeable pave with hexagonal modular pavement systems

    Science.gov (United States)

    Rashid, M. A.; Abustan, I.; Hamzah, M. O.

    2013-06-01

    Modular permeable pavements are alternatives to the traditional impervious asphalt and concrete pavements. Pervious pore spaces in the surface allow for water to infiltrate into the pavement during rainfall events. As of their ability to allow water to quickly infiltrate through the surface, modular permeable pavements allow for reductions in runoff quantity and peak runoff rates. Even in areas where the underlying soil is not ideal for modular permeable pavements, the installation of under drains has still been shown to reflect these reductions. Modular permeable pavements have been regarded as an effective tool in helping with stormwater control. It also affects the water quality of stormwater runoff. Places using modular permeable pavement has been shown to cause a significant decrease in several heavy metal concentrations as well as suspended solids. Removal rates are dependent upon the material used for the pavers and sub-base material, as well as the surface void space. Most heavy metals are captured in the top layers of the void space fill media. Permeable pavements are now considered an effective BMP for reducing stormwater runoff volume and peak flow. This study examines the extent to which such combined pavement systems are capable of handling load from the vehicles. Experimental investigation were undertaken to quantify the compressive characteristics of the modular. Results shows impressive results of achieving high safety factor for daily life vehicles.

  12. Experimental evaluation of high performance base course and road base asphalt concrete with electric arc furnace steel slags.

    Science.gov (United States)

    Pasetto, Marco; Baldo, Nicola

    2010-09-15

    The paper presents the results of a laboratory study aimed at verifying the use of two types of electric arc furnace (EAF) steel slags as substitutes for natural aggregates, in the composition of base course and road base asphalt concrete (BBAC) for flexible pavements. The trial was composed of a preliminary study of the chemical, physical, mechanical and leaching properties of the EAF steel slags, followed by the mix design and performance characterization of the bituminous mixes, through gyratory compaction tests, permanent deformation tests, stiffness modulus tests at various temperatures, fatigue tests and indirect tensile strength tests. All the mixtures with EAF slags presented better mechanical characteristics than those of the corresponding asphalts with natural aggregate and satisfied the requisites for acceptance in the Italian road sector technical standards, thus resulting as suitable for use in road construction. PMID:20566237

  13. Experimental evaluation of high performance base course and road base asphalt concrete with electric arc furnace steel slags.

    Science.gov (United States)

    Pasetto, Marco; Baldo, Nicola

    2010-09-15

    The paper presents the results of a laboratory study aimed at verifying the use of two types of electric arc furnace (EAF) steel slags as substitutes for natural aggregates, in the composition of base course and road base asphalt concrete (BBAC) for flexible pavements. The trial was composed of a preliminary study of the chemical, physical, mechanical and leaching properties of the EAF steel slags, followed by the mix design and performance characterization of the bituminous mixes, through gyratory compaction tests, permanent deformation tests, stiffness modulus tests at various temperatures, fatigue tests and indirect tensile strength tests. All the mixtures with EAF slags presented better mechanical characteristics than those of the corresponding asphalts with natural aggregate and satisfied the requisites for acceptance in the Italian road sector technical standards, thus resulting as suitable for use in road construction.

  14. Pavement Sealcoat, PAHs, and the Environment

    Science.gov (United States)

    Van Metre, P. C.; Mahler, B. J.

    2011-12-01

    Recent research by the USGS has identified coal-tar-based pavement sealants as a major source of polycyclic aromatic hydrocarbons (PAHs) to the environment. Coal-tar-based sealcoat is commonly used to coat parking lots and driveways and is typically is 20-35 percent coal tar pitch, a known human carcinogen. Several PAHs are suspected mutagens, carcinogens, and (or) teratogens. In the central and eastern U.S. where the coal-tar-based sealants dominate use, sum-PAH concentration in dust particles from sealcoated pavement is about 1,000 times higher than in the western U.S. where the asphalt-based formulation is prevalent. Source apportionment modeling indicates that particles from sealcoated pavement are contributing the majority of the PAHs to recent lake sediment in 35 U.S. urban lakes and are the primary cause of upward trends in PAHs in many of these lakes. Mobile particles from parking lots with coal-tar-based sealcoat are tracked indoors, resulting in elevated PAH concentrations in house dust. In a recently completed study, volatilization fluxes of PAHs from sealcoated pavement were estimated to be about 60 times fluxes from unsealed pavement. Using a wide variety of methods, the author and colleagues have shown that coal-tar-based sealcoat is a major source of PAHs to the urban environment and might pose risks to aquatic life and human health.

  15. Nutrient Infiltrate Concentrations from Three Permeable Pavement Types

    Science.gov (United States)

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha...

  16. Full-Depth Asphalt Pavements for Parking Lots and Driveways.

    Science.gov (United States)

    Asphalt Inst., College Park, MD.

    The latest information for designing full-depth asphalt pavements for parking lots and driveways is covered in relationship to the continued increase in vehicle registration. It is based on The Asphalt Institute's Thickness Design Manual, Series No. 1 (MS-1), Seventh Edition, which covers all aspects of asphalt pavement thickness design in detail,…

  17. Research on Fatigue Properties of Asphalt Pavement on Mix Base%混合式基层沥青路面的疲劳特性分析研究

    Institute of Scientific and Technical Information of China (English)

    彭宏图

    2013-01-01

    According to the 06 standard design methods,AASHTO experiment methods and actual interlayer bonding state,the fatigue properties of three different bituminous pavements of composite base are analyzed in this paper.The results reveal that with the same thickness,the mixed asphalt pavement has a better fatigue life than the semi-rigid base AC pavement.For the purpose of analyzing the sensitivity of the fatigue property,the thickness of the pavement and modulus of graded gravel are also taken into account in three different asphalt pavements of composite.%采用了06版规范方法、考虑实际层间粘接状态的规范方法以及AASH00经验方法对3种类型的混合式基层沥青路面的疲劳特性进行了分析研究,得出了相同厚度的混合式基层沥青路面比半刚性基层沥青路面具有更长的疲劳寿命的结论.并对不同结构层厚度、级配碎石模量对3种类型的混合式基层沥青路面的疲劳特性的敏感性进行了分析.

  18. Shakedown analysis of anisotropic asphalt concrete pavements with clay subgrade

    Energy Technology Data Exchange (ETDEWEB)

    Boulbibane, M.; Collins, I.F. [Auckland Univ., Auckland (New Zealand). Dept. of Engineering Science; Weichert, D. [RWTH-Aachen Inst. of General Mechanics, Aachen (Germany); Raad, L. [Alaska-Fairbanks Univ., Fairbanks, AK (United States). Transportation and Research Centre

    2000-08-04

    A mathematical model has been presented which can predict the effect of inherent anisotropic cohesion on the long-term behaviour of multilayered pavements. The model is based on the lower bound theorem of shakedown analysis and makes allowances for variations of soil strength with direction. Pavements operating above the critical shakedown load exhibit plastic strains under long term repeated loading conditions and eventually result in deep ruts. This model was used to examine the influence of subgrade properties on the shakedown behaviour of two-layer pavement systems consisting of an asphalt concrete layer and a granular base over a clay subgrade. The shakedown load for pavements under repeated loadings was estimated and the effects of variables such as temperature, asphalt thickness, stiffness and strength were determined. The materials in the various layers of the pavement were modeled as elastic-plastic Mohr-Coulomb materials. 38 refs., 3 tabs., 5 figs.

  19. An analysis of pavement heat flux to optimize the water efficiency of a pavement-watering method

    International Nuclear Information System (INIS)

    Pavement-watering as a technique of cooling dense urban areas and reducing the urban heat island effect has been studied since the 1990's. The method is currently considered as a potential tool for and climate change adaptation against increasing heat wave intensity and frequency. However, although water consumption necessary to implement this technique is an important aspect for decision makers, optimization of possible watering methods has only rarely been conducted. An analysis of pavement heat flux at a depth of 5 cm and solar irradiance measurements is proposed to attempt to optimize the watering period, cycle frequency and water consumption rate of a pavement-watering method applied in Paris over the summer of 2013. While fine-tuning of the frequency can be conducted on the basis of pavement heat flux observations, the watering rate requires a heat transfer analysis based on a relation established between pavement heat flux and solar irradiance during pavement insolation. From this, it was found that watering conducted during pavement insolation could be optimized to 30-min cycles and water consumption could be reduced by more than 80% while reducing the cooling effect by less than 13%. - Highlights: • The thermal effects of pavement-watering were investigated in Paris, France. • Pavement-watering was found to significantly affect pavement heat flux 5 cm deep. • When insolated, a linear relation was found between heat flux and solar radiation. • Pavement-watering did not alter its slope, but introduced a negative intercept. • Subsequent improvements of the watering period, frequency and rate are proposed

  20. The mechanical response of multi-tower continuous-span suspension bridge deck pavement based on whole bridge analysis

    Institute of Scientific and Technical Information of China (English)

    Li Hongtao; Zhang Chenchen; Hu Jing; Qian Zhendong

    2011-01-01

    The effect of multiple span suspension structure on the mechanical response of bridge deck pavement was studied, and finite element analysis (FEM) of stress and strain of pavement according to the bridge floor system features of super-long and high flexibility was made. Meanwhile, the FEM results were compared with those of the single span suspension structure. Three-stage analytic hierarchy process (AHP) is developed to analyze the mechanical response including whole bridge analysis, partial beams section analysis and orthotropic plate analysis. The most unfavorable load position was determined by the numerical solutions acquired from each stage to study the main mechanical index of multiple span suspension structure. The FEM results showed that the mechanical response numerical solutions by using the three-stage AHP are greater than those by simplified boundary condition, and the force condition of multiple span suspension structure is worse than that of the single span suspension structure.

  1. 柔性基层沥青路面与组合式沥青路面层底拉应力分析%The bottom layer tensile stress analysis of flexible base asphalt pavement and combined asphalt pavement

    Institute of Scientific and Technical Information of China (English)

    姜凤连

    2014-01-01

    对两种典型路面结构层层底拉应力进行对比,分析了基层厚度变化对各层层底拉应力的影响,得出两种路面结构层层底拉应力变化规律,根据其变化规律来选择路面结构材料。%In this paper,two kinds of typical pavement structure layers tensile stress of bottom layer were,the analysis of the impact of the thickness variation on tensile stress of bottom layer.We obtain two kinds of change regulation of pavement structure layers tensile stress of bottom layer, and choose the materials of pavement structure according to the change regulation.

  2. 不同类型基层沥青路面设计指标的控制%Control of designing indices for asphalt pavement with different types of base

    Institute of Scientific and Technical Information of China (English)

    张艳红; 申爱琴; 郭寅川; 王学礼; 冯亚军

    2011-01-01

    Based on the reconstruction and extension project of Xitong expressway, the fatigue and breakage forms of semi-rigid asphalt pavement, compound base asphalt pavement and flexible base asphalt pavement were analyzed and the corresponding design parameter system was established separately. The sensibility of the materials parameter as the mechanical responses was analyzed using Shell designing software Bisar3. 0, which verified the rationality of pavement designing indices from the point of stress balance. The results show that taking flexible strain and surface shear stress as designing indices for flexible pavement could keep the modulus value of semi-rigid base in proper range. Taking flexible stress of base and shear stress of base as designing indices for semi-rigid pavement and compound pavement could constraint the modulus value of semi-rigid base. The introduction of shearing stress is particularly necessary for asphalt pavement design because it can seriously affect material parameters and help optimize both the structure and material design. 9 tabs, 6 figs, 10 refs.%以西安-铜川高速公路改扩建工程为依托,分析半刚性基层沥青路面、复合式基层沥青路面及柔性基层沥青路面的破坏形式,并建立与之相对应的设计指标体系.采用壳牌计算软件Bisar3.0分析材料参数对路面力学响应的敏感性,从路面受力均衡角度验证各类沥青路面设计指标的合理性.结果表明:对柔性路面采取弯拉应变与面层剪应力指标进行双控,可实现基层模量的合理取值;半刚性路面与复合式路面采取基层拉应力与面层剪应力指标进行双控,可对半刚性基层模量起到牵制作用;沥青路面设计增加抗剪指标尤为必要,可对材料参数起到制约作用,实现结构设计与材料设计的双重优化.

  3. Influence Factors of Mechanical Response of Cold Recycled Base Pavement Structure%冷再生基层路面结构力学响应影响因素分析

    Institute of Scientific and Technical Information of China (English)

    侯昭光

    2011-01-01

    针对佛山官西线冷再生路面结构设计,采用有限元计算软件BISAR 3.0分析了原路当量回弹模量、沥青面层厚度、基层厚度和基层模量对冷再生路面结构力学性能的影响,以便为合理的冷再生路面结构设计提供参考.分析表明:原路面当量回弹模量直接决定改建后路面的使用性能;面层越厚,基层抗疲劳性能、路面抗车辙性能增强,路表弯沉减小;冷再生基层模量增加,基层层底易开裂,但当基层模量过小时,面层层底易产生弯拉疲劳,且易产生车辙;基层厚度一般不能低于15 cm.%According to the cold recycled pavement structure design of Guanxi line in Foshan, BISAR3.0 is chosen as the calculation software to study the mechanical response of the equivalent rebounding modulus of the original pavement, the thickness of surface pavement layer, the thickness of cold recycled base and cold recycled base modulus on cold recycled pavement structure performance. Therefore, references for the cold recycled pavement structure design are provided. The analysis shows that the equivalent rebounding modulus of the original pavement directly determines the service performance of the road after the reconstruction; the thicker surface layer, the anti-fatigue properties of base, anti-rutting performance of pavement enhance markedly, and the deflection on the surface reduce; as cold recycled base modulus increases, the bottom of base layers is easy to crack; but when the base modulus is too small, the bottom of surface layers is easy to produce bending fatigue, the pavement is also prone to rutting; so the cold recycled base thickness is of no less than 15cm.

  4. A smartphone based method to enhance road pavement anomaly detection by analyzing the driver behavior

    NARCIS (Netherlands)

    Seraj, Fatjon; Zhang, Kui; Türkes, Okan; Meratnia, Nirvana; Havinga, Paul J.M.

    2015-01-01

    This paper introduces a method to detect road anomalies by analyzing driver behaviours. The analysis is based on the data and the features extracted from smartphone inertial sensors to calculate the angle of swerving and also based on distinctive states of a driver behaviour event. A novel approach

  5. Asphalt pavement temperature prediction

    OpenAIRE

    Minhoto, Manuel; Pais, Jorge; Pereira, Paulo

    2006-01-01

    A 3-D finite element model (FEM) was developed to calculate the lemperature of an asphtalt rubber pavement localed in the Northeast of Portugal. The goal of the case study presented in this paper is to show the good accuracy temperature prediction tha can be obtained with this model when compared with the field pavement thermal condition obtained during a year. lnput data to the model are the hourly values for solar radiation and temperature and the mean daily value of wind speed obtained fr...

  6. Problem-based, interdisciplinary field-based courses

    DEFF Research Database (Denmark)

    Hill, Trevor; Birch-Thomsen, Torben; Traynor, Catherine;

    2008-01-01

    Student field courses at Universities are increasingly incorporating problem-based interdisciplinary approaches to enhance learning opportunities. This paper reports upon seven field-based, problem-oriented, interdisciplinary courses held within southern Africa concerning natural resource...... in a positive manner and a strong respectful working relationship from the staff. We advocate this process as worthwhile as classroom theory becomes real in all applied and complex environment....

  7. Evaluation of accelerated deterioration in NAPTF flexible test pavements

    Institute of Scientific and Technical Information of China (English)

    Kasthurirangan GOPALAKRISHNAN

    2008-01-01

    Previous research studies have successfully demonstrated the use of artificial neural network(ANN)models for predicting critical structural responses and layer moduli of highway flexible pavements.The primary objective of this study was to develop an ANN-based approach for backcalculation of pavement moduli based on heavy weight deflectometer(HWD)test data,especially in the analysis of airport flexible pavements subjected to new generation aircraft(NGA).Two medium-strength subgrade flexible test sections,at the National Airport Pavement Test Facility(NAPTF),were modeled using a finite element(FE) based pavement analysis program,which can consider the non-linear stress-dependent behavior of pavement geomaterials.A multi-layer,feed-forward network which uses an error-backpropagation algorithm was trained to approximate the HWD backcalculation function using the FE program generated synthetic database.At the NAPTF,test sections were subjected to Boeing 777 (B777)trafficking on one lane and Boeing 747(B747)trafficking on the other lane using a test machine.To monitor the effect of traffic and climatic variations on pavement structural responses.HWD tests were conducted on the traffieked lanes and on the untraffieked centerline of test sections as trafficking progressed.The trained ANN models were successfully applied on the actual HWD test data acquired at the NAPTF to predict the asphalt concrete moduli and non-1inear subgrade moduli of the medium-strength subgrade flexible test sections.

  8. Deterioration modeling for condition assessment of flexible pavements considering extreme weather events

    Science.gov (United States)

    Hashemi Tari, Yasamin; Shahini Shamsabadi, Salar; Birken, Ralf; Wang, Ming

    2015-04-01

    Accurate pavement management systems are essential for states' Department Of Transportation and roadway agencies to plan for cost-effective maintenance and repair (M and R) strategies. Pavement deterioration model is an imperative component of any pavement management system since the future budget and M and R plans would be developed based on the predicted pavement performance measures. It is crucial for the pavement deterioration models to consider the factors that significantly aggravate the pavement condition. While many studies have highlighted the impact of different environmental, load, and pavement's structure on the life cycle of the pavement, effect of extreme weather events such as Floods and Snow Storms have often been overlooked. In this study, a pavement deterioration model is proposed which would consider the effect of traffic loads, climate conditions, and extreme weather events. Climate, load and performance data has been compiled for over twenty years and for eight states using the Long Term Pavement Performance (LTPP) and National Oceanic and Atmospheric Administration (NOAA) databases. A stepwise regression approach is undertaken to quantify the effect of the extreme weather events, along with other influential factors on pavement performance in terms of International Roughness Index (IRI). Final results rendered more than 90% correlation with the quantified impact values of extreme weather events.

  9. Permeable Pavements at Purdue

    OpenAIRE

    Knapp, Jim

    2013-01-01

    Two case studies will be presented describing sustainable drainage alternatives. The processes used for the 2nd Street project in Seymour will provide a comparison of the design processes for conventional and green infrastructure solutions. Purdue University will discuss a number of permeable pavement installations on campus and provide a map for viewing. Asphalt, concrete, and permeable paver options will be discussed.

  10. Pervious Pavement System Evaluation

    Science.gov (United States)

    Pervious pavement is a low impact development stormwater control. The Urban Watershed Management Branch of the U.S. Environmental Protection Agency in Edison, NJ, is evaluating concrete pavers as a popular implementation. The pollutant removal of a bench-scale permeable interlo...

  11. Influence of differential settlement on pavement structure of widened roads based on large-scale model test

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    This study introduced at first the background of numerous highway widening projects that have been developed in recent years in China.Using a large ground settlement simulator and a fiber Bragg grating (FBG) strain sensor network system,a large-scale model test,with a similarity ratio of 1:2,was performed to analyze the influence of differential settlement between new and old subgrades on pavement structure under loading condition.The result shows that excessive differential settlement can cause considerabl...

  12. Calibrating mechanistic-empirical pavement performance models with an expert matrix

    Energy Technology Data Exchange (ETDEWEB)

    Tighe, S.; AlAssar, R.; Haas, R. [Waterloo Univ., ON (Canada). Dept. of Civil Engineering; Zhiwei, H. [Stantec Consulting Ltd., Cambridge, ON (Canada)

    2001-07-01

    Proper management of pavement infrastructure requires pavement performance modelling. For the past 20 years, the Ontario Ministry of Transportation has used the Ontario Pavement Analysis of Costs (OPAC) system for pavement design. Pavement needs, however, have changed substantially during that time. To address this need, a new research contract is underway to enhance the model and verify the predictions, particularly at extreme points such as low and high traffic volume pavement design. This initiative included a complete evaluation of the existing OPAC pavement design method, the construction of a new set of pavement performance prediction models, and the development of the flexible pavement design procedure that incorporates reliability analysis. The design was also expanded to include rigid pavement designs and modification of the existing life cycle cost analysis procedure which includes both the agency cost and road user cost. Performance prediction and life-cycle costs were developed based on several factors, including material properties, traffic loads and climate. Construction and maintenance schedules were also considered. The methodology for the calibration and validation of a mechanistic-empirical flexible pavement performance model was described. Mechanistic-empirical design methods combine theory based design such as calculated stresses, strains or deflections with empirical methods, where a measured response is associated with thickness and pavement performance. Elastic layer analysis was used to determine pavement response to determine the most effective design using cumulative Equivalent Single Axle Loads (ESALs), below grade type and layer thickness.The new mechanistic-empirical model separates the environment and traffic effects on performance. This makes it possible to quantify regional differences between Southern and Northern Ontario. In addition, roughness can be calculated in terms of the International Roughness Index or Riding comfort Index

  13. Hydro-Radical Polymer Stabilized Base Material Mechanical Properties and Pavement Structure Analysis%路用水基聚合物稳定基层材料力学性能及路面结构分析

    Institute of Scientific and Technical Information of China (English)

    张敏江; 赵云龙; 于保阳; 欧培冬

    2012-01-01

    Through the study of SRX stabilized base material mechanical properties and SRX flexible base asphalt pavement structural mechanics response results, the aim of this paper is to verify whether the SRX stable material can be used as pavement base layer, and to provide a theoretical basis for the SRX flexible base asphalt pavement structure design. The CBR value and modulus of resilient of SRX stabilized base material were determined by indoor test, application of BISAR software on SRX flexible base asphalt pavement structure and semi-rigid base asphalt pavement structure to analyze the mechanical response,according to the calculation results, two kinds of pavement structure fatigue life were analyzed. The results have shown that the California bearing ratio (CBR) value of SRX flexible material is 227. 85,the modulus of resilience of SRX flexible material is 520 MPa; Two kinds of pavement structure of each has its own characteristics on horizontal stress distribution, structure layer strain distribution, pavement shear stress distribution, deflection and compressive strain on top of subgrade soil and heavy load sensitivity. The conclusion is that SRX stable material can be used as pavement base, but in pavement structure design, the fatigue performance of SRX flexible base materials should be paid much attention; Relative to the SRX flexible base, the fatigue life of semi-rigid base of axle load is more sensitive.%目的 研究SRX稳定基层材料力学性能和SRX柔性基层沥青路面结构力学响应规律,验证SRX稳定材料是否可以用作路面基层,并为SRX柔性基层沥青路面结构设计提供理论依据.方法 通过室内试验确定SRX稳定基层材料的CBR值和回弹模量,应用BISAR软件对SRX柔性基层和半刚性基层沥青路面结构进行力学响应分析,并以此计算结果对两种路面结构的疲劳寿命进行分析.结果 SRX柔性材料的加州承载比(CBR)值为227.85;SRX柔性材料的回弹模量为520MPa;

  14. Assessment of porous asphalt pavement performance: hydraulics and water quality

    Science.gov (United States)

    Briggs, J. F.; Ballestero, T. P.; Roseen, R. M.; Houle, J. J.

    2005-05-01

    The objective of this study is to focus on the water quality treatment and hydraulic performance of a porous asphalt pavement parking lot in Durham, New Hampshire. The site was constructed in October 2004 to assess the suitability of porous asphalt pavement for stormwater management in cold climates. The facility consists of a 4-inch asphalt open-graded friction course layer overlying a high porosity sand and gravel base. This base serves as a storage reservoir in-between storms that can slowly infiltrate groundwater. Details on the design, construction, and cost of the facility will be presented. The porous asphalt pavements is qualitatively monitored for signs of distress, especially those due to cold climate stresses like plowing, sanding, salting, and freeze-thaw cycles. Life cycle predictions are discussed. Surface infiltration rates are measured with a constant head device built specifically to test high infiltration capacity pavements. The test measures infiltration rates in a single 4-inch diameter column temporarily sealed to the pavement at its base. A surface inundation test, as described by Bean, is also conducted as a basis for comparison of results (Bean, 2004). These tests assess infiltration rates soon after installation, throughout the winter, during snowmelt, after a winter of salting, sanding, and plowing, and after vacuuming in the spring. Frost penetration into the subsurface reservoir is monitored with a frost gauge. Hydrologic effects of the system are evaluated. Water levels are monitored in the facility and in surrounding wells with continuously logging pressure transducers. The 6-inch underdrain pipe that conveys excess water in the subsurface reservoir to a riprap pad is also continuously monitored for flow. Since porous asphalt pavement systems infiltrate surface water into the subsurface, it is important to assess whether water quality treatment performance in the subsurface reservoir is adequate. The assumed influent water quality is

  15. 广东省柔性基层沥青路面设计弯沉计算参数研究%Study on Calculation Parameters of Design Deflection for Asphalt Pavement with Flexible Base in Guangdong Province

    Institute of Scientific and Technical Information of China (English)

    黄博彦; 王钊

    2012-01-01

    Through analyzing origin of actual design deflection calculation formula in specification for design of highway asphalt pavement and their applications in Guangdong Province, being combined with highway condition data of several highway asphalt pavement constructed earliest, study on calculation parameters of design deflec- tion for asphalt pavement with flexible base is conducted and the formula of asphalt pavement design deflection calculation is calibrated. By means of mechanically analyzing total thickness of flexible base and condition of flexural tensile stress in coarse bottom of semi-rigid base, composite base and flexible base pavement which are commonly used in Guangdong Province, the applicable situation for different values of deflection calculation pa- rameters is put forward.%通过分析现行沥青路面设计规范中设计弯沉计算公式的由来及在广东省的适用情况,结合广东省最早修建的几条高速公路沥青路面的路况资料,对柔性基层沥青路面设计弯沉相关计算参数进行了研究,标定了沥青路面设计弯沉计算公式。此外,通过力学分析计算广东省内常见的半刚性、组合式及柔性路面结构中柔性层的总厚度及层底弯拉应力的受力状况,提出了弯沉计算参数不同取值的适用条件。

  16. Development of Improved Mechanistic Deterioration Models for Flexible Pavements

    DEFF Research Database (Denmark)

    Ullidtz, Per; Ertman, Hans Larsen

    1998-01-01

    The paper describes a pilot study in Denmark with the main objective of developing improved mechanistic deterioration models for flexible pavements based on an accelerated full scale test on an instrumented pavement in the Danish Road Tessting Machine. The study was the first in "International...... Pavement Subgrade Performance Study" sponsored by the Federal Highway Administration (FHWA), USA. The paper describes in detail the data analysis and the resulting models for rutting, roughness, and a model for the plastic strain in the subgrade.The reader will get an understanding of the work needed...

  17. An Innovative Strategy for Maintenance of Highway Pavement

    Directory of Open Access Journals (Sweden)

    Sandeep Choudhary, Dr. P. K. Agarwal

    2013-05-01

    Full Text Available Highway pavement are deteriorating fast due to lack of timely maintenance, leading to higher vehicle operating costs, increasing number of accidents etc. Thus, timely maintenance of the highway pavement is essential. Because, once pavements start to deteriorate; they deteriorate rapidly beyond the point where maintenance is effective. Thus, there is an urgent need to develop a strategy for maintenance of pavement in a huge highway network. In this study, an innovative strategy for maintenance of highway pavement is proposed. A two stage maintenance strategy is proposed. In stage I, it is proposed to determine priority of highway sections. In Stage II, priority of various maintenance activities to be carried out on various sections will be determined. Maintenance priority of the pavement is based on importance of the road sections, present road conditions, and future road conditions. The methodology proposed in this study is illustrated with the help of example of some hypothetical highway network consisting of 4 sections. Analysis results indicated that the proposed strategy is considered to be more rational, innovative & logical. Some strategies for maintenance of urban roads are also presented in this study. Therefore, it is expected that this study will be useful for maintenance of huge highway network in India and thus will be useful for preserving huge asset of pavement infrastructure.

  18. 广河高速公路柔性基层ATB-25配合比设计及施工控制%Mix Design and Construction Control of Flexible Base Course ATB - 25 of Guanghe Expressway

    Institute of Scientific and Technical Information of China (English)

    廖小军

    2012-01-01

    In combination with mix design and construction control and application practice of flexile base course of asphalt pavement at Guangzhou section of Guanghe Expressway, mix design and construction points and attentions of flexible base course ATB -25 are elaborated emphatically.%结合广河高速公路广州段工程沥青路面柔性基层配合比设计及施工控制应用实践,重点阐述了柔性基层ATB-25配合比设计和施工要点及注意事项。

  19. Comparative Study on Pavement Temperature Features of Bridge Deck and Road Pavement

    OpenAIRE

    Yueqin Hou; Nanxiang Zheng; Yiluo Zhang

    2013-01-01

    The objective of this study was to comparatively analyze the difference of pavement temperature of bride deck and road pavement. The asphalt pavement temperature of road pavement and bride deck were tested in Guozigou area of Xinjiang, China. And the air temperature, wind speed, humidness and sunlight radiation were collected. Further, the distribution features of asphalt pavement of bridge deck and road pavement were comparatively analyzed. At last, the predictive model of pavement temperatu...

  20. Adaptation of AASHTO Pavement Design Guide for Local Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hajek, J.J. [Applied Research Associates Inc., Toronto, ON (Canada)

    2001-07-01

    The methodology used to adapt the 1993 AASHTO Guide for Design of Pavement Structures to Ontario conditions was described. The guide expresses the effect of traffic loads on pavement performance using the concept of axle Load Equivalency Factors (LEF). LEF is regarded as a pavement damage factor assigned to each specific load and axle configuration. The size of LEF is related to the damage that is expected to occur from a standard load of 80 kN carried by a single axle with dual tires. The factors are summarized to yield the number of Equivalent Single Axle Loads (ESALs) a pavement is expected to sustain during its life. A summary was also provided of the additional work done to prepare for the transition to the proposed mechanistically-based 2002 AASHTO Guide. The paper focused only on the design of flexible pavements in terms of load characterization using equivalent single axle loads along with axle load spectra, below grade and material characterization, plus initial and terminal serviceability and reliability. The AASHTO Guide uses two parameters to deal with design reliability: design reliability level and overall standard deviation. Data collected on Ontario highway pavements and materials was used for assessing the design inputs. Other data was also collected from research and development studies, laboratory experiments, and from a survey of experienced pavement design engineers. The end result was a new grouping of Ontario soils for pavement design, recommended values for the resilient modulus of below grade soils, recommendations for structural layer coefficients for Ontario pavement materials and recommendations for the initial pavement serviceability based on Ontario smoothness specifications. Results of calibration and verification processes indicate that for new flexible pavements, the AASHTO-Ontario model is in good agreement with the observed results. It was recommended that the calibration and verification of the AASHTO-Ontario model should be a

  1. Asphalt for draining pavement; Haisuisei hosoyo asphalt

    Energy Technology Data Exchange (ETDEWEB)

    Yamamori, H.; Nakamura, Y. [Mitsubishi Oil Co. Ltd., Tokyo (Japan)

    1994-12-28

    The effect and functions of draining pavement with a superb performance as a paved road were introduced. In the draining pavement, a porous asphalt mixture was used for the surface and base layers of the road and the remaining layers are not in water penetration property. It is necessary that void continues to prevent water film from being generated when rain falls and resistance against water flow is small but durability has problems when the void rate is large. According to the balance, the void rate ranges from 20 to 23 % for execution, thus preventing water splash on a rainy day, hydroplaning, and dazzlement, etc. due to reflection of light. The noise during driving due to the tire of an automobile is reduced by 5 to 6 dB owing to draining pavement. Also, engine noise is reduced to 40 - 60 % since the surface is porous. In the draining pavement, a high-viscosity asphalt is used for a binder and the void rate is large, thus preventing temperature to rise easily due to heat release and achieving an improved flow behavior. 6 refs., 11 figs., 14 tabs.

  2. Urban pavement surface temperature. Comparison of numerical and statistical approach

    Science.gov (United States)

    Marchetti, Mario; Khalifa, Abderrahmen; Bues, Michel; Bouilloud, Ludovic; Martin, Eric; Chancibaut, Katia

    2015-04-01

    The forecast of pavement surface temperature is very specific in the context of urban winter maintenance. to manage snow plowing and salting of roads. Such forecast mainly relies on numerical models based on a description of the energy balance between the atmosphere, the buildings and the pavement, with a canyon configuration. Nevertheless, there is a specific need in the physical description and the numerical implementation of the traffic in the energy flux balance. This traffic was originally considered as a constant. Many changes were performed in a numerical model to describe as accurately as possible the traffic effects on this urban energy balance, such as tires friction, pavement-air exchange coefficient, and infrared flux neat balance. Some experiments based on infrared thermography and radiometry were then conducted to quantify the effect fo traffic on urban pavement surface. Based on meteorological data, corresponding pavement temperature forecast were calculated and were compared with fiels measurements. Results indicated a good agreement between the forecast from the numerical model based on this energy balance approach. A complementary forecast approach based on principal component analysis (PCA) and partial least-square regression (PLS) was also developed, with data from thermal mapping usng infrared radiometry. The forecast of pavement surface temperature with air temperature was obtained in the specific case of urban configurtation, and considering traffic into measurements used for the statistical analysis. A comparison between results from the numerical model based on energy balance, and PCA/PLS was then conducted, indicating the advantages and limits of each approach.

  3. 基于累积损伤因子的水泥混凝土路面设计%Cement concrete pavement design based on cumulative damage factor

    Institute of Scientific and Technical Information of China (English)

    蔡良才; 朱占卿; 吴爱红; 潘正华; 王维国

    2012-01-01

    Based on the compositive fatigue equation of load fatigue stress and temperature fatigue stress, the coverage-to-pass ratios of single-axle-single-wheel load and single-axle-double-wheel load were calculated by adopting cumulative damage factor. A direct calculating method of total cumulative fatigue damage of pavement structure produced by multi-axle load and a new design method of cement concrete pavement were put forward by replacing design axle load with cumulative damage factor. The accuracy and application feasibility of calculating fatigue damage produced by multi-axle load were done through a design example with two types of traffic volumes. Analysis result indicates that the acting times of multi-axle load at all points on the cross section of highway are different, and the peak value of cumulative damage of each axle load may be not at the same location. The thicknesses of worst pavement places under the traffic volumes calculated by the design method based on cumulative damage factor are all 22 cm, which meets the design requirement, and the thicknesses of other places can reduce according to the cumulative damage curve. Thereby, it can avoid the differences and localizations of present specification design method of concrete pavement based on standard axle load and equivalent fatigue consumption principle. 1 tab, 8 figs, 12 refs.%考虑荷载疲劳应力和温度疲劳应力的综合疲劳方程,计算了单轴单轮及单轴双轮轴载的覆盖通行率,利用累积损伤因子替代标准轴载在交通量换算中的作用,提出了直接计算各级轴载对路面结构总的累积疲劳损伤方法和新的水泥混凝土路面设计方法,并采用两组交通量对轴载累积损伤量的计算方法的准确性与可行性进行了验证。分析结果表明:公路横断面上各点处轴载的作用次数是不同的,各级轴载的累积疲劳损伤峰值不一定在同一位置,利用基于累积损伤因子的水泥混凝土路面设计

  4. Asynchronous, web-based course in astronomy

    Science.gov (United States)

    Spergel, M.

    The course described here is a general educational, non-prerequisite and non- mathematical college course in astronomy offered on the web. It consists of readings from the text plus other periodical sources both online and offline. The course also requires the student to utilize a virtual planetarium to perform exercises in viewing the sky. The students respond to conceptual, multiple-choice questions. This course gives the student a sense of the night sky through the use of computer simulations and night observation. The students learn to understand and express scientific ideas. In addition, since the course is enhanced in computer usage and writing, students also develop these important skills.

  5. 基于非线性疲劳损伤特性的沥青路面形变规律%Deformation Regularity of Asphalt Pavement Based on Nonlinear Fatigue Damage Characteristics

    Institute of Scientific and Technical Information of China (English)

    孙志林; 黄晓明

    2012-01-01

    In order to study the fatigue damage characteristic and deformation regularity of asphalt pavement under vehicle load, by using the general finite element software ABAQUS and the secondary development platform, an asphalt pavement numerical model which considers pavement material nonlinear fatigue damage was established to analyze the spatial distribution/evolution of asphalt pavement structure damages, the spatial distribution/evolution of asphalt pavement structure horizontal normal strains, and the evolution of pavement surface deflection varying with loads under repeated vehicle load. The results show that (1) The pavement structural damage mainly distributes in a specific damage zone located at the bottom of the layer along the middle line between the double wheels. With the increasing of load cycles, the damage degrees at the bottom of the base layer and the sub-base layer increase, and the rate of which gradually increases. (2) The horizontal tensile strain close to the bottom of the pavement layer increases, the rate of which gradually increases, and neutral axis moves upward. (3) The deflection of pavement surface increases with the increase of load cycles, and the rate of which increases gradually. The regularity is in agreement with related measured results. The results can provide a theoretical support for asphalt pavement structure design, maintenance and prediction of the long-term performance.%为了研究沥青路面结构在车辆荷载作用下的疲劳损伤演化特性,并分析其形变规律,运用通用有限元软件ABAQUS及其二次开发平台,建立考虑路面材料非线性疲劳损伤的沥青路面结构数值计算模型,分析沥青路面结构在车辆荷载反复作用下路面结构损伤和路面结构水平正应变的空间分布及演化规律,以及路表弯沉随荷载作用的演变规律.结果表明:路面结构损伤主要分布在双轮中心线下靠近层底的区域,基层层底与底基层层底损伤度随荷载

  6. NonPAS: A Program for Nonlinear Analysis of Flexible Pavements

    Directory of Open Access Journals (Sweden)

    Ali Reza Ghanizadeh

    2015-06-01

    Full Text Available The primary step in design of a pavement using Mechanistic-Empirical (M-E method is the analysis of pavement and calculation of the critical responses of pavement under various loadings. This confirms the need for developing pavement analysis software as an analytical base of the M-E method. To this end, NonPAS program has been developed for linear and nonlinear analysis of flexible pavements. Developed program allows nonlinear analysis of flexible pavements using five nonlinear models, including K-θ, Uzan, Uzan-Witczak, MEPDG 2002 and Bilinear models. Nonlinear Analysis of flexible pavements by utilizing these constitutive models provides a more accurate modeling of granular material behavior. Developed program can be used to analyze a pavement system consists of maximum of 10 layers, which is subjected to a maximum of six circular loads. Developed program allows for calculating the responses at 400 different points of pavement. In order to validate the results of linear and nonlinear analysis, responses obtained from NonPAS have been compared with responses obtained using Kenlayer program. Results show very good agreement between responses, which are obtained using both linear and nonlinear analysis and approve that developed program can be used with high reliability for the purposes of pavement analysis and design.

  7. Course Redesign: An Evidence-Based Approach

    Directory of Open Access Journals (Sweden)

    Kathy Nomme

    2014-11-01

    Full Text Available A first year non-majors biology course, with an enrollment of around 440 students, has been redesigned from a course of traditional content and teaching style to one that emphasizes biological concepts in current global issues and incorporates active learning strategies. We were informed by the education literature incorporating many aspects of established curriculum redesign principles and extended its application to a biology course. Systematic measurement of student attitudes and collection of student feedback through a series of surveys as well as focus group interviews proved to be invaluable in the course redesign process. The information gathered over a two-year period enabled us to fine-tune the course content and teaching strategies effectively to better meet the interests of students in the non-majors course as was documented by the evidence gathered in this research.

  8. A Theory Based Introductory Programming Course

    DEFF Research Database (Denmark)

    Hansen, Michael Reichhardt; Kristensen, Jens Thyge; Rischel, Hans

    1999-01-01

    This paper presents an introductory programming course designed to teach programming as an intellectual activity. The course emphasizes understandable concepts which can be useful in designing programs, while the oddities of today's technology are considered of secondary importance. An important......, intellectual activity where the solution of a programming problem can be described in an understandable way. The approach is illustrated by an example which is a commented solution of a problem posed to the students in the course....

  9. Geotextiles in Flexible Pavement Construction

    Science.gov (United States)

    Alungbe, Gabriel D.

    2004-01-01

    People everywhere in the developed world regularly drive on paved roads. Learning about the construction techniques and materials used in paving benefits technology and construction students. This article discusses the use of geosynthetic textiles in pavement construction. It presents background on pavements and describes geotextiles and drainage…

  10. Pavement roughness and skid properties

    Science.gov (United States)

    Road roughness and roadway safety as it relates to both surface and air transportation are discussed. The role of road roughness in vehicle ride, the measurement of roughness, the evaluation of riding confort, and the effect of grooving pavements are discussed. The effects of differential pavement friction on the response of cars in skidding maneuvers is discussed.

  11. Procedures and Technologies for Pavement Monitoring

    OpenAIRE

    GEORGE, Luc Amaury; Brosseaud, Yves

    2009-01-01

    Pavement Monitoring (surface and structure). Surface characteristics - main indicators Pavement structures (non destructive testings). Monitoring objectives. Devices and indicators used in France Innovation & Research. Measurement's use by roads owners. Main road network (States & motorway concessionaires). Local and urban road networks. Some maintenance techniques. High modulus mixtures and very thin mixtures. Pavement in situ recycling Pavement in plan recycling. Low noise & coloured ...

  12. 混合式基层沥青路面结构应力、应变特性及经济性分析%Mechanical 、Economic and Budget Analysis of Asphalt Pavement Structure on Mix Base

    Institute of Scientific and Technical Information of China (English)

    彭红卫; 蒋功雪; 朱沅峰

    2012-01-01

    Based on asphalt pavement design theory and criterions in China, five asphalt structures are put out, including three mix base pavement structures, one typical semi-rigid base pavement structure and one typical flexible base pavement structure. For contract study, different pavement structures were selected with various combinations of modulus and Poisson ratio, but the total thickness is same for comparative analysis. The stress-strain at different depth in asphalt layer is calculated by using BISAR program. The data analysis is carried out for the maximum tensile stress, and the maximum strain of asphalt layer, and the maximum compressive strain on top of sub grade, deflection on asphalt surface. And budget basis price for base is contrasted too. The data analysis results show that the mix base asphalt pavement structures can be designed to get better pavement mechanical performance than typical semi-rigid base and typical flexible base asphalt pavement structures, while the price is higher than semi-rigid base. If thinking over fatigue life, the cost performance for mix base of upper base with asphalt stabilized macadam is the best. This gives out the important reference for widespread the mix base in future.%基于我国沥青路面设计理论及标准,拟定了3种混合式基层、一种典型半刚性基层与一种典型柔性基层共5种沥青路面结构,利用BISAR3.0程序对5种结构进行力学计算分析.主要针对5种路面结构的沥青层内最大拉应力、最大拉应变、路基顶面压应变、路表弯沉等力学指标进行深入对比分析,并根据疲劳寿命对各类基层进行了经济性分析.数据分析结果表明:通过合理的设计,混合式基层结构在力学性能上可以较典型半刚性基层和柔性基层结构更加优秀,虽然从单价上来讲,经济性能上不如半刚性基层,但考虑路面疲劳寿命性价的话,采用沥青稳定碎石作为上基层的混合式基层可以优于半刚性基

  13. Analysis of asphalt pavements with flexible base using viscoelastic three-dimensional finite element method%柔性基层沥青路面结构粘弹性三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    陈诚诚; 刘俊卿; 王保实; 李倩

    2015-01-01

    以沈大高速公路沈鞍段路面结构为例,在温度变化时考虑沥青混合料粘弹性影响,建立了柔性基层沥青路面温度场疲劳断裂模型,借用三维有限元实现交通荷载及温度荷载耦合作用下路面结构的动力特性. 研究多场耦合作用下柔性基层沥青路面结构的破坏行为. 研究表明:荷载在移动过程中剪切型应力强度因子对路面开裂起控制作用;降温时张开型应力强度因子是沥青路面开裂破坏的主要因素;对柔性基层沥青路面结构考虑变温和交通荷载耦合作用下的疲劳寿命预估,结果显示,该方法与实际更为接近.%Taking the pavement structure of Shen-An period in Shen-Da highway as the example and considering the asphalt mixture viscoelasticity when temperature changed, the fatigue fracture model of flexible base asphalt pavement in temperature field was established. Then using the three dimensional finite element technology, the dynamic properties of the pavement structure under the coupling action of the traffic and temperature load were achieved and the destructive action of flexible base asphalt pavement was also analyzed under the action of multiple field coupling. The study showed that in the process of pavement cracking, the shear stress intensity factor played a control role as the load moved and the opening mode stress intensity factor was the critical role as the temperature felled. Predicting the fatigue life of flexible base asphalt pavement by considering the coupling action of the traffic and temperature load,the result showed this method was almost completely approaching the reality.

  14. Stormwater quality of spring-summer-fall effluent from three partial-infiltration permeable pavement systems and conventional asphalt pavement.

    Science.gov (United States)

    Drake, Jennifer; Bradford, Andrea; Van Seters, Tim

    2014-06-15

    This study examined the spring, summer and fall water quality performance of three partial-infiltration permeable pavement (PP) systems and a conventional asphalt pavement in Ontario. The study, conducted between 2010 and 2012, compared the water quality of effluent from two Interlocking Permeable Concrete Pavements (AquaPave(®) and Eco-Optiloc(®)) and a Hydromedia(®) Pervious Concrete pavement with runoff from an Asphalt control pavement. The usage of permeable pavements can mitigate the impact of urbanization on receiving surface water systems through quantity control and stormwater treatment. The PP systems provided excellent stormwater treatment for petroleum hydrocarbons, total suspended solids, metals (copper, iron, manganese and zinc) and nutrients (total-nitrogen and total-phosphorus) by reducing event mean concentrations (EMC) as well as total pollutant loadings. The PPs significantly reduced the concentration and loading of ammonia (NH4(+)+NH3), nitrite (NO2(-)) and organic-nitrogen (Org-N) but increased the concentration and loading of nitrate (NO3(-)). The PP systems had mixed performances for the treatment of phosphate (PO4(3-)). The PP systems increased the concentration of sodium (Na) and chloride (Cl) but EMCs remained well below recommended levels for drinking water quality. Relative to the observed runoff, winter road salt was released more slowly from the PP systems resulting in elevated spring and early-summer Cl and Na concentrations in effluent. PP materials were found to introduce dissolved solids into the infiltrating stormwater. The release of these pollutants was verified by additional laboratory scale testing of the individual pavement and aggregate materials at the University of Guelph. Pollutant concentrations were greatest during the first few months after construction and declined rapidly over the course of the study.

  15. Stormwater quality of spring-summer-fall effluent from three partial-infiltration permeable pavement systems and conventional asphalt pavement.

    Science.gov (United States)

    Drake, Jennifer; Bradford, Andrea; Van Seters, Tim

    2014-06-15

    This study examined the spring, summer and fall water quality performance of three partial-infiltration permeable pavement (PP) systems and a conventional asphalt pavement in Ontario. The study, conducted between 2010 and 2012, compared the water quality of effluent from two Interlocking Permeable Concrete Pavements (AquaPave(®) and Eco-Optiloc(®)) and a Hydromedia(®) Pervious Concrete pavement with runoff from an Asphalt control pavement. The usage of permeable pavements can mitigate the impact of urbanization on receiving surface water systems through quantity control and stormwater treatment. The PP systems provided excellent stormwater treatment for petroleum hydrocarbons, total suspended solids, metals (copper, iron, manganese and zinc) and nutrients (total-nitrogen and total-phosphorus) by reducing event mean concentrations (EMC) as well as total pollutant loadings. The PPs significantly reduced the concentration and loading of ammonia (NH4(+)+NH3), nitrite (NO2(-)) and organic-nitrogen (Org-N) but increased the concentration and loading of nitrate (NO3(-)). The PP systems had mixed performances for the treatment of phosphate (PO4(3-)). The PP systems increased the concentration of sodium (Na) and chloride (Cl) but EMCs remained well below recommended levels for drinking water quality. Relative to the observed runoff, winter road salt was released more slowly from the PP systems resulting in elevated spring and early-summer Cl and Na concentrations in effluent. PP materials were found to introduce dissolved solids into the infiltrating stormwater. The release of these pollutants was verified by additional laboratory scale testing of the individual pavement and aggregate materials at the University of Guelph. Pollutant concentrations were greatest during the first few months after construction and declined rapidly over the course of the study. PMID:24681366

  16. Field evaluation of in-situ test technology for Q(C)/Q(A) during construction of pavement layers and embankments

    Science.gov (United States)

    Nazzal, Munir Darwish

    2007-12-01

    This dissertation documents the results of an extensive research study that was conducted to characterize the behavior of geogrid reinforced base course materials. The research was conducted through an experimental testing and numerical modeling programs. The experimental testing program included performing different laboratory tests to evaluate the effect of various factors on the performance geogrid reinforced base course materials. Finite element models were also developed to investigate the benefits of placing geogrids within the base course layer in a flexible pavement structure. The results of the experimental testing demonstrated that the inclusion of the geogrid reinforcement layer(s) improved the compressive strength and stiffness of base course materials under static loading. This improvement was more pronounced at higher strain levels. Furthermore, the results showed that the geogrid significantly reduced the base course material permanent deformation under cyclic loading, but it did not show appreciable effect on their resilient deformation. The results also showed that for stress levels less than the plastic shakedown stress limit, the geogrid had a minimum contribution to the permanent deformation resistance during primary post-compaction stage; however, it significantly increased this resistance during the secondary stage. The results also showed that the change in the moisture content of the base material altered its state of stress; this significantly affected the geogrid improvement. The finite modeling program showed that the geogrid reinforcement reduced the lateral, vertical, and shear strains within the base course and subgrade layers. Furthermore, the geogrid had appreciable reduction in permanent deformation for pavement sections built on top of weak subgrade soils with medium to thin base layer thickness; with the thin base layer thickness showing greater values of improvement. However, negligible to modest reinforcement effect on permanent

  17. Evaluation of pavement skid resistance using high speed texture measurement

    Directory of Open Access Journals (Sweden)

    Jay N. Meegoda

    2015-12-01

    Full Text Available Skid resistance is an important parameter for highway designs, construction, management, maintenance and safety. The purpose of this manuscript is to propose the correlation between skid resistance, which is measured as skid resistance trailer, and mean profile depth (MPD or the macro surface texture, which is measured by vehicle mounted laser, so that highway agencies can predict the skid resistance of pavement without the use of expensive and time consuming skid resistance trailer, which also causes disruption of traffic in use. In this research skid numbers and MPD from 5 new asphalt pavements and 4 old asphalt pavements were collected using a locked wheel skid trailer and a vehicle mounted laser. Using the data collected, a correlation between the skid number (SN40R collected by locked wheel skid tester and the texture data or MPD collected by a vehicle mounted laser operating at highway speeds was developed. The proposed correlation for new pavements was positive for MPD values less than 0.75 mm to reach a peak SN40R value, then there was a negative correlation as the MPD increases until the MPD value was equal to 1.1 mm and beyond the MPD value of 1.1 mm to the maximum value of 1.4 mm, SN40R value remained almost constant. There were significant data scatter for the MPD value of 0.8 mm. To explain these results, water film thickness during the friction test was calculated and the critical MPD was defined. The effect of sealed water pool on the SN40R was discussed. The test result showed a similar trend for older asphalt pavements, but with lower SN40R values due to the polishing of pavement micro-texture by traffic. Hence, a reduction factor was proposed for older pavements based on cumulative traffic volume for the above correlation to predict the skid resistance of older pavements.

  18. Application Study on Geotextile as Bond-Breaking Layer Between Concrete Pavement Slab and Lean Concrete Base%土工布作水泥混凝土路面隔离层应用研究

    Institute of Scientific and Technical Information of China (English)

    林天干; 姚佳良; 于远征; 袁剑波

    2012-01-01

    主要结合广东、湖南等省高速公路中采用土工布作水泥混凝土路面隔离层进行的路面层间力学性能试验与工程应用研究,探讨了贫混凝土基层上铺筑水泥混凝土面层时采用土工布隔离层与无隔离层时的层间力学性能差别.通过现场试验路施工,总结了土工布用于路面隔离层的施工控制技术.获得的土工布隔离层层间力学性能参数与施工应用技术,为实体工程路面设计、施工控制提供了科学依据.%This research explored the difference in mechanical performance of slab-base interface between the pavements without a bond-breaking layer and the pavements with geotextile as the bond-breaking layer installed between the concrete pavement surface slab and the lean concrete base, via the field tests for mechanical performance of slab-base interface treated with geotextile as the bond-breaking layers in some highway projects of Hunan and Guangdong Provinces. The techniques of construction control in placing geotextile atop the lean concrete base as the bond-breaking layer is concluded from the construction of the field test roads. The mechanical performance of slab-base interface with geotextile as the bond-brea king medium derived from this research and the techniques of construction offer scientific reference to pavement design and construction control in the practical road engineering projects.

  19. 轴距对柔性基层沥青路面轴数系数的影响研究%Influence of wheelbase parameters on Equivalent Axle-number Coefficient of Asphalt Pavement with flexibility Base

    Institute of Scientific and Technical Information of China (English)

    康荣根

    2014-01-01

    应用弹性层状体系理论计算程序,考虑轴距变化的影响,计算柔性基层沥青路面轴载换算公式中的轴数系数。针对典型柔性基层沥青路面结构组成,以路表最大弯沉为验算指标,计算并总结归纳出适合柔性基层沥青路面典型结构的轴数系数。%By use of program based on layer-elastic theory,with wheelbase parameters,the axle-number coefficient in the axle-load conversion formula for semi-rigid asphalt pavement is calculated .Through analyzing the results, the axle-number coeffi cient in Asphalt Pavement with fl exibility Base is concluded.

  20. Noise emission of concrete pavement surfaces produced by diamond grinding

    Directory of Open Access Journals (Sweden)

    Jens Skarabis

    2015-04-01

    Full Text Available In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, the relationship among surface texture, concrete composition and noise emission of concrete pavement surfaces has been systematically investigated. The simulation program SPERoN was used in a parameter study to investigate the main factors which affect noise emission. Based on the results of the simulations, textured concrete surfaces were produced by using a laboratory grinding machine. As well as the composition of the concrete, the thickness and spacing of the diamond blades were varied. The ability of the textured surfaces to reduce noise emission was assessed from the texture characteristics and air flow resistance of textured surfaces measured in the laboratory. It was found that concrete composition and, in particular, the spacing of the blades affected the reduction in noise emission considerably. The noise emission behaviour of numerous road sections was also considered in field investigations. The pavement surfaces had been textured by diamond grinding during the last years or decades. The results show that diamond grinding is able to provide good, durable noise-reducing properties. Several new pavement sections were investigated using thicknesses and spacings of the blades similar to those used in the laboratory to optimize noise emission reduction. It is concluded that diamond grinding is a good alternative to exposed aggregate concrete for the production of low-noise pavement surfaces.

  1. Competency-Based Education: A Framework for Measuring Quality Courses

    Science.gov (United States)

    Krause, Jackie; Dias, Laura Portolese; Schedler, Chris

    2015-01-01

    The growth of competency-based education in an online environment requires the development and measurement of quality competency-based courses. While quality measures for online courses have been developed and standardized, they do not directly align with emerging best practices and principles in the design of quality competency-based online…

  2. Cracks Long-term Development Law of Asphalt Pavement with Different Base Types%不同基层类型沥青路面裂缝的长期发展规律

    Institute of Scientific and Technical Information of China (English)

    高玲玲; 张艳聪

    2015-01-01

    In order to determine the effect of base structures on cracks long-term development law of asphalt pavement,the number and distribution of cracks of six test freeways in Shanxi province were investigated.It contains three base types (flexible base,semi-rigid base and rigid base)and two base thicknesses (50cm and 55cm).The investigating time was four years after construction and four years after overlay.The results showed that:number,area and development speed of asphalt pavement with semi-rigid base were significantly bigger than pavement with flexible base and rigid base.In-creasing thickness of semi-rigid base can reduce the number and area of cracks,but it was limited for rigid and flexible base.Cracks development law of pavement after overlay was similar to new pave-ment.Overlay is more valuable for pavement with flexible base.%为探讨基层类型对沥青路面裂缝长期发展规律的影响,针对山西某高速公路3种基层类型(柔性基层、半刚性基层、刚性基层)、2种基层厚度(50,55 cm)的6段沥青路面试验路,于铺筑后连续4年、加铺后连续4年测定了路面裂缝数目和分布规律的发展情况。结果表明,半刚性基层沥青路面的裂缝数目、开裂面积及其发展速度均明显大于刚性和柔性基层;增加基层厚度可以减少半刚性基层沥青路面裂缝数目和开裂面积,但对于刚性基层和柔性基层路面作用有限;加铺后路面裂缝的发展规律与新建路面相似,加铺对于柔性基层路面意义更大。

  3. Numerical modeling of inelastic structures at loading of steady state rolling. Thermo-mechanical asphalt pavement computation

    Science.gov (United States)

    Wollny, Ines; Hartung, Felix; Kaliske, Michael

    2016-05-01

    In order to gain a deeper knowledge of the interactions in the coupled tire-pavement-system, e.g. for the future design of durable pavement structures, the paper presents recent results of research in the field of theoretical-numerical asphalt pavement modeling at material and structural level, whereby the focus is on a realistic and numerically efficient computation of pavements under rolling tire load by using the finite element method based on an Arbitrary Lagrangian Eulerian (ALE) formulation. Inelastic material descriptions are included into the ALE frame efficiently by a recently developed unsplit history update procedure. New is also the implementation of a viscoelastic cohesive zone model into the ALE pavement formulation to describe the interaction of the single pavement layers. The viscoelastic cohesive zone model is further extended to account for the normal pressure dependent shear behavior of the bonding layer. Another novelty is that thermo-mechanical effects are taken into account by a coupling of the mechanical ALE pavement computation to a transient thermal computation of the pavement cross-section to obtain the varying temperature distributions of the pavement due to climatic impact. Then, each ALE pavement simulation considers the temperature dependent asphalt material model that includes elastic, viscous and plastic behavior at finite strains and the temperature dependent viscoelastic cohesive zone formulation. The temperature dependent material parameters of the asphalt layers and the interfacial layers are fitted to experimental data. Results of coupled tire-pavement computations are presented to demonstrate potential fields of application.

  4. Test on Dynamic Response of Flexible Base Asphalt Pavement%柔性基层沥青路面动力响应试槽试验

    Institute of Scientific and Technical Information of China (English)

    李起伟; 黎晓; 梁乃兴

    2012-01-01

    根据室内试槽柔性基层沥青路面结构的重复加载试验,总结了路用电阻应变片的选择依据和黏贴工艺,对比分析了压路机压实方式对应变片存活率的影响;利用惠斯登电桥电路测试了柔性基层沥青路面的动力响应,并与数值计算进行对比.研究表明:路用电阻应变片栅长应大于80 mm,并与集料的最大公称粒径相关;电阻应变片在压路机静压的方式下有较理想的存活率,而在强振作用下却极难存活;在移动荷载作用下沥青面层底部横向应变交替出现拉、压应变,其最大值比层状弹性体系模型计算值小.%According to repeated load test of flexible base asphalt pavement, the structure is built in the indoor pit. The principle of choosing resistance strain gauges and the surface-sticking process of gauge was summarized; the survival rate of strain gauge based on the comparison of road roller' s compaction mode strong vibration or static pressure was discussed. The data of time-history curves was collected through the Wheatstone Bridge with the numerical calculation comparative study. The detection results show; the gate length of resistance strain gauge should not be less than 80mm, which is related to nominal maximum size of aggregate. Gauges' survival rate is affected by different compaction model, which is much lower under the strong vibration model. Also the response of. strain in layer bottom under the dynamic load of moving vehicle is more complex than that in static situation. However, the current pavement structure design method needs transforming from static model to dynamic load model.

  5. Research on Nonlinear Property and Granular Base Modulus of Flexible Base Asphalt Pavement%柔性基层沥青路面非线性特性及模量研究

    Institute of Scientific and Technical Information of China (English)

    何兆益; 唐伯明

    2001-01-01

    Through laboratory research and theory analysis , the nonlinear property of semi-rigid asphalt pavement with granular (upper)base is studied and the modulus values of granular (upper)base is suggested. It is proved that the modulus of traditional flexible base is further smaller than granular(upper)base.In addition, the nonlinear property of granular (upper)base is advantageous to the fatigue of pavement.%从室内试验和理论分析两方面研究具有碎石上基层的半刚性沥青路面非线性特性和碎石上基层模量合理取值,研究结果表明碎石上基层具有比传统柔性基层高得多的弹性模量,此外碎石上基层非线性特性有利于重交通对路面的疲劳作用。

  6. Mechanical Analysis on Influence of Flexible Base Modulus and Thickness on Inverted Pavement Structure%柔性基层模量及厚度对倒装式路面结构受力影响分析

    Institute of Scientific and Technical Information of China (English)

    王为义; 陈景雅; 吴菲; 王健

    2016-01-01

    In order to research the influence of flexible base parameters on inverted structure pavement, the study used ABAQUS software to establish a three-dimensional pavement structure model and analyzed mechanical properties of asphalt pavement structure with different flexible base modulus and thickness. Calculation results showed that increasing thickness of flexible base could reduce road surface deflection and decrease stress of se-mi-rigid base layer tensile at the bottom, but had adverse effects on tensile stress of asphalt layer at the bottom and the fatigue life of the pavement; thickness of flexible base had less effects on shear stress in surface layer;increasing modulus of flexible base was beneficial to the mechanical indexes of pavement. Through comprehen-sive analysis of various indicators, the study concluded that a reasonable modulus of flexible base was from 450 to 500MPa and a reasonable thickness of the flexible base was from 10 to 15cm.%为研究柔性基层参数对倒装式路面结构的受力影响,利用ABAQUS有限元软件建立倒装式路面结构模型,分析在不同柔性基层模量及厚度下倒装式沥青路面结构的各项力学性质。计算结果表明:增加柔性基层厚度可以降低路表弯沉值,改善半刚性基层底部拉应力,但是对面层底部拉应力以及沥青面层疲劳寿命不利,对面层中剪应力值影响较小;提高柔性基层模量对各项力学指标均有利。综合考虑各项指标,建议柔性基层模量取450~500 MPa,柔性基层厚度取10~15 cm。

  7. "Full-Scale Testing of Pavement Response"

    DEFF Research Database (Denmark)

    Ullidtz, Per; Ekdahl, Peter

    1998-01-01

    -analysing FWD data and for calculating the stresses and the strains, the simple method based on Odemark's transformations and Boussinesq's equations appeared to be as good as, or better than, the more sophisticated methods using layered elastic theory or the Finite Element Method.......Three pavement sections in southern Sweden were instrumented in late 1991. Each section have instruments for measuring the strain at the bottom of the asphalt layer, vertical stress and strains in the subgrade and temperatures at different depths. The purpose was to evaluate different theoretical...... methods for determining stresses, strains and deflections in pavement structurers.Falling Weight Deflectometer (FWD) test were done on the test sections, and stresses and strains were measured both under FWD loading and under a rolling wheel load. Different back-analysis procedures were used to derive...

  8. The Dependence of Physical Mechanical Properties of Concrete Pavement Blocks on Coarse Aggregate Type

    Directory of Open Access Journals (Sweden)

    Malaiškienė Jurgita

    2014-12-01

    Full Text Available The aim of this research is to determine the dependences of the physical mechanical properties of vibropressed concrete (pavement blocks on the type of coarse aggregate used in the main layer. Sustainability of concrete pavement blocks is a really important matter. Five different batches of pavement blocks were produced, changing the consistence ratio of coarse aggregate in the main layer. There are two types of course aggregate: crushed gravel and granite. The consistence of a facing layer was not changed. All tests: density, tensile split strength, water absorption for vibro-pressed concrete units were made according to EN 1338:2003+AC2006.

  9. Improving Student Engagement Using Course-Based Social Networks

    Science.gov (United States)

    Imlawi, Jehad Mohammad

    2013-01-01

    This study proposes an engagement model that supports use of course-based online social networks for engaging student, and hence, improving their educational outcomes. This research demonstrates that instructors who create course-based online social networks to communicate with students can increase the student engagement in these online social…

  10. Project Based Case Learning and Massive Open Online Courses

    Science.gov (United States)

    Jian, Bo; Yang, Cheng

    2015-01-01

    In this article, the authors provide a new approach to massive open online course: project based case learning. Although there are many online teaching websites, such as Coursera and Edx, most of the courses are video based. That is, students learn knowledge through watching lecture videos. This method may apply to theoretical subjects, but for…

  11. Pervious Pavement System Evaluation- Abstract

    Science.gov (United States)

    Porous pavement is a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete pavers as a popular implementation. The pavers themselves are impermeable, but the spaces between the pavers are backfilled with washed, gra...

  12. Architecture of a MOOC based on CourseBuilder

    OpenAIRE

    Pernías Peco, Pedro; Luján Mora, Sergio

    2013-01-01

    This paper focuses on the development of Uni-MOOC aemprende, a MOOC (Massive Open Online Course) based on Google CourseBuilder. Firstly, we discuss the current available platforms aimed to develop MOOCs: before developing UniMOOC aemprende, different MOOC platforms were reviewed in order to choose the most suitable for our requirements. Then, we explain why we selected Google CourseBuilder as the most suitable option for the requirements of our MOOC. Finally, we present the architecture of ou...

  13. A Course in Heterogeneous Catalysis Involving Video-Based Seminars.

    Science.gov (United States)

    White, Mark G.

    1984-01-01

    A video-based format was used during a graduate seminar course designed to educate students on the nature of catalysis, to help transfer information among students working on similar problems, and to improve communication skills. The mechanics of and student reaction to this seminar course are discussed. (JN)

  14. Implementing Problem-Based Learning in an Undergraduate Psychology Course

    Science.gov (United States)

    Searight, H. Russell; Searight, Barbara K.

    2009-01-01

    Problem-based learning (PBL) is a small-group pedagogical technique widely used in fields such as business, medicine, engineering, and architecture. In PBL, pre-written cases are used to teach core course content. PBL advocates state that course material is more likely to be retained and applied when presented as cases reflecting "real life"…

  15. An Honors Interdisciplinary Community-Based Research Course

    Science.gov (United States)

    Dunbar, David; Terlecki, Melissa; Watterson, Nancy; Ratmansky, Lisa

    2013-01-01

    This article describes how two faculty members at Cabrini College--one from biology and the other from psychology--incorporated interdisciplinary community-based research in an honors course on environmental watershed issues. The course, Environmental Psychology, was team-taught in partnership with a local watershed organization, the Valley Creek…

  16. A Framework for Concept-Based Digital Course Libraries

    Science.gov (United States)

    Dicheva, Darina; Dichev, Christo

    2004-01-01

    This article presents a general framework for building conceptbased digital course libraries. The framework is based on the idea of using a conceptual structure that represents a subject domain ontology for classification of the course library content. Two aspects, domain conceptualization, which supports findability and ontologies, which support…

  17. Developing a Competency-based Fundamentals of Management Communication Course.

    Science.gov (United States)

    Murranka, Patricia A.; Lynch, David

    1999-01-01

    Describes steps the authors went through to develop an innovative course in fundamentals of management communication that derives from competency-based instruction. Describes how they reviewed administrative and course parameters; identified instructional modules and generated competencies for each one; and created objectives, achievement levels,…

  18. Introducing Process Competences in a PBL-based Engineering Course

    DEFF Research Database (Denmark)

    Soler, José; Andersson, Pernille Hammar

    2013-01-01

    The article describes an experiment in which elements related to generic professional competences, such as group work methodology, project planning, task delegation and communication, have been introduced in an existing course, tailored as a Problem Base Learning (PBL) course in Advanced...

  19. Numerical analysis of applying special pavements to solve the frost heave diseases of high-speed railway roadbeds in seasonally frozen ground regions

    Institute of Scientific and Technical Information of China (English)

    Chang Yuan; FuJun Niu; QiHao Yu; XinBin Wang; Lei Guo; YanHui You

    2015-01-01

    The Haerbin-Dalian Passenger Dedicated Line is the first high-speed railway constructed in the seasonally frozen ground regions of northeastern China. Frost heave diseases occurred in the first winter of its operation (between October 2012 and January 2013), and frost heave was observed mainly in the roadbed fills that were considered not susceptible to frost heave. This paper proposes applying two special pavements — black pavement and insulation-black pavement — to improve the thermal regime of the roadbed. Three numerical models of the roadbed temperature field were built based on the field con-ditions of the Changchun section (D3K692+840 to D3K692+860). The results show that: (1) Compared with cement pave-ment, black pavement and insulation-black pavement could reduce the freezing index at the roadbed surface by 37% and 64%, respectively, which could influence the maximum frozen depth; (2) the maximum frozen depths under the black pavement and insulation-black pavement were respectively 1.3–1.4 m and 1 m. Compared with cement pavement, they could reduce the maximum frozen depth by 0.4 m and 0.7–0.8 m, respectively, which would reduce the permitted amount of frost heave by 4 mm and 7–8 mm, which would meet the deformation limit established by theCode for Design on Special Subgrade of Railway; (3) the freezing periods of the black pavement and the insulation-black pavement were, respectively, approximately four months and two months. Compared with cement pavement, they could reduce the freezing period by approximately 19 days and 40 days, respectively, and delay the initial freezing time by 9 days and 18 days; and (4) compared with cement pavement, black pavement and black-insulation pavement could reduce the frozen areas of roadbeds in the cold season, which suggests that these two special pavements could provide better thermal stability for roadbeds.

  20. Modeling of unsaturated granular materials in flexible pavements

    Directory of Open Access Journals (Sweden)

    Gu Fan

    2016-01-01

    Full Text Available The unsaturated granular material (UGM is found to exhibit the moisture-sensitive and stress-dependent nonlinear cross-anisotropic behaviour in flexible pavements. This paper aims at developing a finite element (FE model for pavement structure, which takes into account this behaviour of UGM. First, the Lytton model is employed to characterize the moisture-sensitive and stress-dependent behaviour of UGM, which incorporated a matric suction term to the existing stress-dependent constitutive model. The Lytton model is validated by the laboratory resilient modulus tests on the selected UGMs at different moisture contents. Second, the nonlinear cross-anisotropic constitutive equation of UGM is derived from the generalized Hooke’s Law. The coefficients of the constitutive model are determined by the rapid triaxial test. Third, a User-Defined Material (UMAT subroutine is developed to characterize this constitutive behaviour in the FE software ABAQUS. The UMAT subroutine adopts the secant stiffness approach with multiple damping factors. The UMAT subroutine is then implemented in the FE model of flexible pavement structures. The FE simulation results indicate the nonlinear cross-anisotropic model predicts greater pavement responses than the isotropic model. When the UGM is suction sensitive, it is found that the moisture content of UGM significantly affects the moduli distribution of base layer and the critical strains (i.e., tensile strain at the bottom of asphalt concrete, and compressive strains in base and subgrade layers of pavement structures.

  1. Quantifying Evaporation in a Permeable Pavement System

    Science.gov (United States)

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  2. Dynamic contracting mechanism for pavement maintenance management

    NARCIS (Netherlands)

    Demirel, H.C.; De Ridder, H.A.J.

    2013-01-01

    Technological advances, financial possibilities and changes of demands have increasingly affected the pavement maintenance environment for outsourcing in recent years. This induces complexity in the contracting methods of pavement maintenance activities. Despite the fact that current contracting pra

  3. Pervious Pavement System Evaluation-Poster

    Science.gov (United States)

    Pervious pavement is a low impact development stormwater control. The Environmental Protection Agency's Urban Watershed Management Branch is evaluating interlocking concrete pavingstone pervious pavement systems. The pavingstones themselves are impermeable, but the spaces between...

  4. Integrated wave propagation devices for quality control or diagnostics of pavements

    Science.gov (United States)

    Nazarian, Soheil; Yuan, Deren; Baker, Mark R.; Crain, Kevin

    1996-11-01

    Seismic Pavement Analyzer and a portable version of it have been extensively used for quality control and monitoring the structural condition of pavements. With them, a pavement can be tested at closely spaced points and at a fraction of the cost and time of coring. The main tests used are the impact echo for determining the thickness of the slab, ultrasonic body wave and ultrasonic surface wave for determining the moduli of top layer, impulse response for determining the condition of subgrade, and SASW method for determining the modulus profile of pavement. Based on extensive field testing on numerous types of base and subgrade,the techniques in general, and the two devices in particular are quite suitable for many quality and pavement evaluation projects.

  5. 基于加速加载试验的微表处长期路用性能%Accelerated Test-based Study of Long-term Pavement Performance of Micro-surfacing

    Institute of Scientific and Technical Information of China (English)

    孙晓立; 张肖宁; 蔡旭

    2012-01-01

    A distinct deviation appears between the results of the test methods of micro-surfacing technical guideline and actual pavement performance, which influences the micro-surfacing application. Based on driving wheel pavement analyzer, the indoor accelerated test on micro-surfacing was carried out to study the impact of aggregate gradation, type and content of padding, content of polypropylene fiber on the anti-slip performance and wear resistance of micro-surfacing. Test results show that coarse gradation micro-surfacing is of the higher anti-slip performance and worse wear resistance than those of fine gradation micro-surfacing. The wear resistance performance can be improved by increasing the content of cement or mineral filler. Polypropylene fiber can improve the anti-slip and wear resistance performance. Test results also show that the interaction between tires and pavement can be simulated by driving wheel pavement analyzer, as a result, the performance of pavement surface can be evaluated quantitatively and efficiently.%现有微表处技术指南中评价微表处路用性能的试验方法与实际情况差异较大,影响了微表处技术的应用与发展.以轮胎驱动式路面功能加速加载试验系统为基础试验平台,通过室内加速加载试验研究集料级配、填料类型与用量和聚丙烯纤维用量等对微表处混合料抗滑性能和耐磨耗性能的影响.试验研究结果表明:粗级配微表处的抗滑性能相对较好,然而耐磨耗性能相对细级配微表处要差;适当增加水泥或添加矿粉都可以较大地提高微表处的耐磨耗性能;掺入适当比例的聚丙烯纤维可以显著提高微表处的抗滑性能和耐磨耗性能.研究结果同时表明了轮胎驱动式路面功能加速加载试验系统可真实模拟轮胎与路面间的相互作用,快速和定量评价路面的表面功能.

  6. Recycling of asphalt pavements with asphalt rubber

    OpenAIRE

    Pais, Jorge; Pereira, Paulo; Minhoto, Manuel; Baptista, António

    2008-01-01

    Pavement recycling has been an important rehabilitation technique to deal with reclaimed materials from old pavements which are usually sent to landfills. The application of this technique contributes to: i) the accomplishment of the requirements defined by the European legislation for the amount of material sent to landfills; ii) the reduction in the use of new raw materials used to produce pavement layers. The reduction of materials to be used in pavement rehabilitation has also been possib...

  7. Water quality and quantity assessment of pervious pavements performance in experimental car park areas.

    Science.gov (United States)

    Sañudo-Fontaneda, Luis A; Charlesworth, Susanne M; Castro-Fresno, Daniel; Andres-Valeri, Valerio C A; Rodriguez-Hernandez, Jorge

    2014-01-01

    Pervious pavements have become one of the most used sustainable urban drainage system (SUDS) techniques in car parks. This research paper presents the results of monitoring water quality from several experimental car park areas designed and constructed in Spain with bays made of interlocking concrete block pavement, porous asphalt, polymer-modified porous concrete and reinforced grass with plastic and concrete cells. Moreover, two different sub-base materials were used (limestone aggregates and basic oxygen furnace slag). This study therefore encompasses the majority of the materials used as permeable surfaces and sub-base layers all over the world. Effluent from the test bays was monitored for dissolved oxygen, pH, electric conductivity, total suspended solids, turbidity and total petroleum hydrocarbons in order to analyze the behaviour shown by each combination of surface and sub-base materials. In addition, permeability tests were undertaken in all car parks using the 'Laboratorio Caminos Santander' permeameter and the Cantabrian Portable Infiltrometer. All results are presented together with the influence of surface and sub-base materials on water quality indicators using bivariate correlation statistical analysis at a confidence level of 95%. The polymer-modified porous concrete surface course in combination with limestone aggregate sub-base presented the best performance.

  8. Water quality and quantity assessment of pervious pavements performance in experimental car park areas.

    Science.gov (United States)

    Sañudo-Fontaneda, Luis A; Charlesworth, Susanne M; Castro-Fresno, Daniel; Andres-Valeri, Valerio C A; Rodriguez-Hernandez, Jorge

    2014-01-01

    Pervious pavements have become one of the most used sustainable urban drainage system (SUDS) techniques in car parks. This research paper presents the results of monitoring water quality from several experimental car park areas designed and constructed in Spain with bays made of interlocking concrete block pavement, porous asphalt, polymer-modified porous concrete and reinforced grass with plastic and concrete cells. Moreover, two different sub-base materials were used (limestone aggregates and basic oxygen furnace slag). This study therefore encompasses the majority of the materials used as permeable surfaces and sub-base layers all over the world. Effluent from the test bays was monitored for dissolved oxygen, pH, electric conductivity, total suspended solids, turbidity and total petroleum hydrocarbons in order to analyze the behaviour shown by each combination of surface and sub-base materials. In addition, permeability tests were undertaken in all car parks using the 'Laboratorio Caminos Santander' permeameter and the Cantabrian Portable Infiltrometer. All results are presented together with the influence of surface and sub-base materials on water quality indicators using bivariate correlation statistical analysis at a confidence level of 95%. The polymer-modified porous concrete surface course in combination with limestone aggregate sub-base presented the best performance. PMID:24718346

  9. Determination of Pavement Rehabilitation Activities through a Permutation Algorithm

    Directory of Open Access Journals (Sweden)

    Sangyum Lee

    2013-01-01

    Full Text Available This paper presents a mathematical programming model for optimal pavement rehabilitation planning. The model maximized the rehabilitation area through a newly developed permutation algorithm, based on the procedures outlined in the harmony search (HS algorithm. Additionally, the proposed algorithm was based on an optimal solution method for the problem of multilocation rehabilitation activities on pavement structure, using empirical deterioration and rehabilitation effectiveness models, according to a limited maintenance budget. Thus, nonlinear pavement performance and rehabilitation activity decision models were used to maximize the objective functions of the rehabilitation area within a limited budget, through the permutation algorithm. Our results showed that the heuristic permutation algorithm provided a good optimum in terms of maximizing the rehabilitation area, compared with a method of the worst-first maintenance currently used in Seoul.

  10. Use of scrap rubber in asphalt pavement surfaces

    Science.gov (United States)

    Eaton, Robert A.; Roberts, Richard J.; Blackburn, Robert R.

    1991-12-01

    Scrap tire rubber was mixed into an asphalt concrete wearing course to study the effect of ice disbonding from the pavement surface under traffic. Rubber contents of 0, 3, 6, and 12 percent by weight were studied. Initial laboratory ice disbonding test results led to the development of a new paving material, Chunk Rubber Asphalt Concrete (CRAC), that uses larger pieces of rubber in a much denser asphalt concrete mix. Strength values doubled and ice disbonding performance was enhanced.

  11. A Comparative Study of Competency-Based Courses Demonstrating a Potential Measure of Course Quality and Student Success

    Science.gov (United States)

    Krause, Jackie; Dias, Laura Portolese; Schedler, Chris

    2015-01-01

    While competency-based education is growing, standardized tools for evaluating the unique characteristics of course design in this domain are still under development. This preliminary research study evaluated the effectiveness of a rubric developed for assessing course design of competency-based courses in an undergraduate Information Technology…

  12. Pavement Subgrade Performance Study in the Danish Road Testing Machine

    DEFF Research Database (Denmark)

    Ullidtz, Per; Ertman Larsen, Hans Jørgen

    1997-01-01

    Most existing pavement subgrade criteria are based on the AASHO Road Test, where only one material was tested and for only one climatic condition. To study the validity of these criteria and to refine the criteria a co-operative research program entitled the "International Pavement Subgrade...... Performance Study" was sponsored by the FHWA with American, Finnish and Danish partners. This paper describes the first test series which was carried out in the Danish Road Testing Machine (RTM).The first step in this program is a full scale test on an instrumented pavement in the Danish Road Testing Machine...... of elasticity to calculate the stresses and strains at the position of the gauges and to compare these values to the stresses and strains recorded under the rolling wheel load.Plastic strains resulting from 50 000 applications of each of two load levels (20 kN and 40 kN) were recorded, as well as the permanent...

  13. RAPID INSPECTION OF PAVEMENT MARKINGS USING MOBILE LIDAR POINT CLOUDS

    Directory of Open Access Journals (Sweden)

    H. Zhang

    2016-06-01

    Full Text Available This study aims at building a robust semi-automated pavement marking extraction workflow based on the use of mobile LiDAR point clouds. The proposed workflow consists of three components: preprocessing, extraction, and classification. In preprocessing, the mobile LiDAR point clouds are converted into the radiometrically corrected intensity imagery of the road surface. Then the pavement markings are automatically extracted with the intensity using a set of algorithms, including Otsu’s thresholding, neighbor-counting filtering, and region growing. Finally, the extracted pavement markings are classified with the geometric parameters using a manually defined decision tree. Case studies are conducted using the mobile LiDAR dataset acquired in Xiamen (Fujian, China with different road environments by the RIEGL VMX-450 system. The results demonstrated that the proposed workflow and our software tool can achieve 93% in completeness, 95% in correctness, and 94% in F-score when using Xiamen dataset.

  14. Rapid Inspection of Pavement Markings Using Mobile LIDAR Point Clouds

    Science.gov (United States)

    Zhang, Haocheng; Li, Jonathan; Cheng, Ming; Wang, Cheng

    2016-06-01

    This study aims at building a robust semi-automated pavement marking extraction workflow based on the use of mobile LiDAR point clouds. The proposed workflow consists of three components: preprocessing, extraction, and classification. In preprocessing, the mobile LiDAR point clouds are converted into the radiometrically corrected intensity imagery of the road surface. Then the pavement markings are automatically extracted with the intensity using a set of algorithms, including Otsu's thresholding, neighbor-counting filtering, and region growing. Finally, the extracted pavement markings are classified with the geometric parameters using a manually defined decision tree. Case studies are conducted using the mobile LiDAR dataset acquired in Xiamen (Fujian, China) with different road environments by the RIEGL VMX-450 system. The results demonstrated that the proposed workflow and our software tool can achieve 93% in completeness, 95% in correctness, and 94% in F-score when using Xiamen dataset.

  15. Pavement Roughness Measurement System Based on Distributed Sensors%基于分布式传感器的路面平整度检测系统

    Institute of Scientific and Technical Information of China (English)

    邓海斌; 柳颖臣; 杜豫川; 刘成龙

    2016-01-01

    In order to solve the disadvantages of traditional profile-based roughness measurement meth⁃ods, such as time consuming, strenuosity and high cost, a measurement system was proposed from the perspective of system response, combined with wireless sensors technology. Pavement roughness system was developed by calculating international roughness index using the vibration of vehicles suspension system. Whereby, several high precision triaxial-acceleration sensors were used to collect vehicular vi⁃bration data. To guarantee the stability of data transmission, a short-ranged wireless communication de⁃vice Zigbee was applied. Data labels were proposed to conduct data fusion. A 3G module was utilized to connect the vehicle data and information center. The acceleration power spectral density analysis was conducted to evaluate the international roughness index (IRI), as well as published and stored the results with e-map. The field tests demonstrate the multiple linear relationship between international roughness index and vehicle suspension system vibration. Compared with the data measured by via laser roughness detection devices, the measuring error of this system is basically under 10%, meeting the need of roadmaintenance activities, which is appropriate for wide range pavement roughness measurement.%为解决传统基于断面高程的平整度检测方法耗时费力、价格昂贵等问题,从系统响应的角度出发,结合无线传感技术与谱密度分析法等,通过测量车辆悬架的振动变化推算了路面的平整度,构建了平整度快速采集系统,包括数据采集设备、车载数据终端及信息处理应用。其中,利用高精度三轴传感器采集车辆不同位点的振动信息,利用Zigbee短程无线传输技术保证数据的实时采集与稳定传输,利用数据标签实现多源信息融合,通过3G模块实现车辆数据与信息中心的平台对接,借助加速度功率谱密度分析模型实时

  16. An interactive Web-based radiation protection course in fluoroscopy

    International Nuclear Information System (INIS)

    The teaching of radiation protection to a large group of physicians, who are separated geographically and have complicated schedules, is a formidable problem. Therefore a Web-based solution is attractive, allowing access to the material at any time and place. In this implementation the didactic material is presented in a Web-based format. Subsequently, students attend a practical demonstration in one of the departments' fluoroscopy rooms. Because of local experience with distance education, WebCT was chosen to present the material. WebCT (Web Course Tools) was developed by the University of British Columbia (UBC) to allow educators, with or without technical expertise, to create a sophisticated Web-base. Authors use a standard Web browser to create courses, and students use their browsers to access course material. WebCT provides a wide variety of tools and features that can be added to a course. Among the most useful tools used in this fluoroscopy course are the glossary, multiple-choice questions for each section, and a final test which is scored by the computer. As with all Web-based material the courses can be viewed in the traditional linear fashion or in any random way through the use of linkages. (author)

  17. A Framework for a WAP-Based Course Registration System

    Science.gov (United States)

    AL-Bastaki, Yousif; Al-Ajeeli, Abid

    2005-01-01

    This paper describes a WAP-based course registration system designed and implemented to facilitating the process of students' registration at Bahrain University. The framework will support many opportunities for applying WAP based technology to many services such as wireless commerce, cashless payment... and location-based services. The paper…

  18. Incorporating Code-Based Software in an Introductory Statistics Course

    Science.gov (United States)

    Doehler, Kirsten; Taylor, Laura

    2015-01-01

    This article is based on the experiences of two statistics professors who have taught students to write and effectively utilize code-based software in a college-level introductory statistics course. Advantages of using software and code-based software in this context are discussed. Suggestions are made on how to ease students into using code with…

  19. RCR Online Course: Build an Online Course to Augment RCR Training Using Evidenced-Based Learning Theory

    OpenAIRE

    Ratliff, Mary; Masen, Nicole; Sullivan, Stephen; Michael F. Fleming; Carney, Paula

    2012-01-01

    This article demonstrates how to apply evidenced-based instructional design principles to develop a supplemental, online Responsible Conduct of Research (RCR) course. The supplement RCR course may serve to appropriately augment the National Institutes of Health (NIH) required RCR training. The way to ensure that an online RCR course is effective is to incorporate evidence-based learning theories into the development of the course content. This article specifically demonstrates application of ...

  20. Implementation of a Project-Based Telecommunication Engineering Design Course

    OpenAIRE

    Ali Akbarian, Hadi; Soh, Ping Jack; Farsi, Saeed; Xu, Hantao; Van Lil, Emmanuel; Nauwelaers, Bart; Vandenbosch, Guy; Schreurs, Dominique

    2014-01-01

    This paper describes and discusses the implementation of a project-based graduate design course in Telecommunication Engineering. This course, which requires a combination of technical and softskills for its completion, enables guided independent learning (GIL) and application of technical knowledge acquired from classroom learning. Its main implementation challenge is the need for instructors to define graduate-level GIL activities which are unique for the project objectives and scope. This ...

  1. Use of Ground Penetrating Radar at the FAA's National Airport Pavement Test Facility

    Science.gov (United States)

    Injun, Song

    2015-04-01

    The Federal Aviation Administration (FAA) in the United States has used a ground-coupled Ground Penetrating Radar (GPR) at the National Airport Pavement Test Facility (NAPTF) since 2005. One of the primary objectives of the testing at the facility is to provide full-scale pavement response and failure information for use in airplane landing gear design and configuration studies. During the traffic testing at the facility, a GSSI GPR system was used to develop new procedures for monitoring Hot Mix Asphalt (HMA) pavement density changes that is directly related to pavement failure. After reviewing current setups for data acquisition software and procedures for identifying different pavement layers, dielectric constant and pavement thickness were selected as dominant parameters controlling HMA properties provided by GPR. A new methodology showing HMA density changes in terms of dielectric constant variations, called dielectric sweep test, was developed and applied in full-scale pavement test. The dielectric constant changes were successfully monitored with increasing airplane traffic numbers. The changes were compared to pavement performance data (permanent deformation). The measured dielectric constants based on the known HMA thicknesses were also compared with computed dielectric constants using an equation from ASTM D4748-98 Standard Test Method for Determining the Thickness of Bound Pavement Layers Using Short-Pulse Radar. Six inches diameter cylindrical cores were taken after construction and traffic testing for the HMA layer bulk specific gravity. The measured bulk specific gravity was also compared to monitor HMA density changes caused by aircraft traffic conditions. Additionally this presentation will review the applications of the FAA's ground-coupled GPR on embedded rebar identification in concrete pavement, sewer pipes in soil, and gage identifications in 3D plots.

  2. Teaching Methodology of Flexible Pavement Materials and Pavement Systems

    Science.gov (United States)

    Mehta, Yusuf; Najafi, Fazil

    2004-01-01

    Flexible pavement materials exhibit complex mechanical behavior, in the sense, that they not only show stress and temperature dependency but also are sensitive to moisture conditions. This complex behavior presents a great challenge to the faculty in bringing across the level of complexity and providing the concepts needed to understand them. The…

  3. 基于BOTDA的钢桥面铺装裂缝疲劳扩展研究%A study on crack fatigue propagation of steel deck pavement based on BOTDA

    Institute of Scientific and Technical Information of China (English)

    钱振东; 韩光义; 黄卫; 尹祖超

    2009-01-01

    The fatigue propagation of cracking in epoxy asphalt concrete surfacing of steel decks was studied by using BOTDA sensing technology. Based on indoor three-point bending tests of composite beams composed of pavement and steel plate with cuts, the propagation process of cracking was monitored. The number of times of fatigue load action and the optical fiber strain values in each layer at various levels, including initial pavement cracking and cracking propagation till failure, were obtained. The formulas of crack fatigue propagation model with optical fiber strain e as the variable and the fatigue propagation patterns of cracking in pavement were presented. The results may serve as the base for the fatigue resistant and cracking resistant design of steel decks with epoxy asphalt concrete surfacing.%采用分布式光纤传感技术BOTDA研究钢桥面环氧沥青混凝土铺装层裂缝的疲劳扩展规律.通过由铺装层和钢板组成的带切口复合梁的室内三点弯曲疲劳试验,采用BOTDA监测铺装层裂缝疲劳扩展过程,得到铺装层启裂、裂缝扩展直至破坏的各级疲劳荷载作用次数以及埋设于各层的光纤应变值,给出以光纤应变ε为变量的铺装层裂缝扩展模型公式和铺装层裂缝的疲劳扩展规律,本研究成果为钢桥面环氧沥青混凝土铺装层的抗裂设计和抗疲劳设计提供理论基础.

  4. Introducing Risk Management Techniques Within Project Based Software Engineering Courses

    Science.gov (United States)

    Port, Daniel; Boehm, Barry

    2002-03-01

    In 1996, USC switched its core two-semester software engineering course from a hypothetical-project, homework-and-exam course based on the Bloom taxonomy of educational objectives (knowledge, comprehension, application, analysis, synthesis, and evaluation). The revised course is a real-client team-project course based on the CRESST model of learning objectives (content understanding, problem solving, collaboration, communication, and self-regulation). We used the CRESST cognitive demands analysis to determine the necessary student skills required for software risk management and the other major project activities, and have been refining the approach over the last 5 years of experience, including revised versions for one-semester undergraduate and graduate project course at Columbia. This paper summarizes our experiences in evolving the risk management aspects of the project course. These have helped us mature more general techniques such as risk-driven specifications, domain-specific simplifier and complicator lists, and the schedule as an independent variable (SAIV) process model. The largely positive results in terms of review of pass / fail rates, client evaluations, product adoption rates, and hiring manager feedback are summarized as well.

  5. 基于路面再生技术的道路重建工程研究%Study on road reconstruction project pavement recycling technology based on

    Institute of Scientific and Technical Information of China (English)

    王祥铭; 游仁清

    2014-01-01

    本文从水泥混凝土路面再生技术、现场冷再生技术、沥青再生技术三个方面对于路面再生技术在道路重建工程中的应用进行了探讨。施工过程中,不仅提高了工程的经济效益,缩短了工期,还起到了保护环境的作用。%This article from the cement concrete pavement recycling technology, cold in place recycling technology of asphalt recycling technology, three aspects for pavement recycling technology in road recon-struction project in the application are discussed. In the process of construction, not only improve the econ-omy benefit of the project, shorten the construction period, also played the role of Protect environment.

  6. Revised Design-Based Research Methodology for College Course Improvement and Application to Education Courses in Japan

    Science.gov (United States)

    Akahori, Kanji

    2011-01-01

    The author describes a research methodology for college course improvement, and applies the results to education courses. In Japan, it is usually difficult to carry out research on college course improvement, because faculty cannot introduce experimental design approaches based on control and treatment groupings of students in actual classroom…

  7. Tuning in to pavement radio

    NARCIS (Netherlands)

    Ellis, S.D.K.

    1989-01-01

    This article describes a phenomenon known all over Africa, for which there is no really satisfactory term in English but which is summed up in the French term 'radio trottoir', literally 'pavement radio'. It may be defined as the popular and unofficial discussion of current affairs in Africa, partic

  8. The Concrete and Pavement Challenge

    Science.gov (United States)

    Roman, Harry T.

    2012-01-01

    The modern world is characterized by the extensive use of concrete and asphalt pavement. Periodically, these materials are replaced and the old materials disposed of. In this challenge, students will be asked to develop ways to reuse the old materials. It is important for students to understand how concrete and asphalt are made and applied, as…

  9. Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.

    Science.gov (United States)

    Ma, Feng; Sha, Aimin; Lin, Ruiyu; Huang, Yue; Wang, Chao

    2016-03-22

    In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase.

  10. Determination of allowable subgrade frost heave with the pavement roughness index in numerical analysis

    Institute of Scientific and Technical Information of China (English)

    HongYan Ma; Feng Zhang; DeCheng Feng; Bo Lin

    2015-01-01

    Frost heave is an upward swelling of soil during cryogenic conditions in cold regions. It is caused by the accumulation of ice crystals in subgrade soil, which grow upwards when freezing temperatures penetrate into the subgrade. This study establishes the allowable soil subgrade frost heave based on the roughness standard of asphalt pavement in China, and aims to balance the pavement design and frost heave resistance of subgrades in cold regions. We formulated a mechanical model of pavement supported by the boundary conditions of differential frost heave, based on the elastic layered system theory. The differential soil subgrade frost heave was modeled as a sinusoidal function, and the allowable frost heave and the roughness index were modeled as the displacement boundaries for the top and bottom of the pavement structure. Then the allowable frost heave was back-calculated according to the roughness standard. Numerical results show that the allowable frost heave depends on the pavement structure, material properties, the highway grade, and other factors. In order to ensure that the actual soil subgrade frost heave is lower than the allowable frost heave, pavement structures and materials need to be selected and designed carefully. The numerical method proposed here can be applied to establish the frost heave re-sistance of subgrade when the pavement structure and materials are determined.

  11. Greenhouse Gas Emissions from Asphalt Pavement Construction: A Case Study in China.

    Science.gov (United States)

    Ma, Feng; Sha, Aimin; Lin, Ruiyu; Huang, Yue; Wang, Chao

    2016-03-01

    In China, the construction of asphalt pavement has a significant impact on the environment, and energy use and greenhouse gas (GHG) emissions from asphalt pavement construction have been receiving increasing attention in recent years. At present, there is no universal criterion for the evaluation of GHG emissions in asphalt pavement construction. This paper proposes to define the system boundaries for GHG emissions from asphalt pavement by using a process-based life cycle assessment method. A method for evaluating GHG emissions from asphalt pavement construction is suggested. The paper reports a case study of GHG emissions from a typical asphalt pavement construction project in China. The results show that the greenhouse gas emissions from the mixture mixing phase are the highest, and account for about 54% of the total amount. The second highest GHG emission phase is the production of raw materials. For GHG emissions of cement stabilized base/subbase, the production of raw materials emits the most, about 98%. The GHG emission for cement production alone is about 92%. The results indicate that any measures to reduce GHG emissions from asphalt pavement construction should be focused on the raw materials manufacturing stage. If the raw materials production phase is excluded, the measures to reduce GHG emissions should be aimed at the mixture mixing phase. PMID:27011196

  12. Decision Making Research on Preventive Maintenance Measures for Pavement Based on AHP- Fuzzy Comprehensive Evaluation%基于AHP-模糊综合评价的路面预防性养护措施决策研究

    Institute of Scientific and Technical Information of China (English)

    王淼

    2012-01-01

    预防性养护是一种在路面状况尚处于良好情况下采取的对现有道路系统进行有计划的、基于费用效益的养护策略.养护措施的选择应针对不同路况采取不同的策略.以唐山市某国道工程为实例,介绍采用AHP -模糊综合评价法得到路面预防性养护的最佳措施.%The preventive maintenance ia a planned maintenance polices for existing road system based on cost effectiveness in the case that the pavement conditions are still perfect. The selection of maintenance measures should take different polices in allusion of different road conditions. Based on some national highway project in Tangshan as an example, this paper introduces the optimal measures for preventive maintenance of pavement obtained by means of the AHP - fuzzy comprehensive evaluation method.

  13. PROBLEM BASED LEARNING IN MANAGEMENT AND CLINICAL ENGINEERING COURSE

    Directory of Open Access Journals (Sweden)

    Nur Azah Hamzaid

    2012-07-01

    Full Text Available This paper addressed student perceptions and opinion of the problem based learning method, as well as the empirically collected data on students' learning outcomes on a Biomedical Engineering course, i.e. Management and Clinical Engineering. Pure lecture delivery with absence of practical intervention was deemed insufficient to provide appropriate means to achieve the course objectives. Therefore, a Mock Company assignment was introduced in this course as a problem based learning application aimed to aid the achievement of the program outcome while improving the attainment of the course objectives. The students were divided into groups to form individual mock company. Each mock company formed their organization post for each member, and came up with a business plan for a new project to be presented for fund approval by the panels, made up of the course instructors and invited lecturers from the clinical engineering industry and hospital practitioners. The company discussion progress and performance were monitored by the instructors through the formal university e- learning platform throughout the semester with occasional response and suggestions. The panels identified the expected lack of business and management knowledge but this was counteracted by the reasonably successful business plan produced independently by all companies’ At the end of the semester, through questionnaires, 69.6% of the 56 students agreed that this mock company assignment was useful in achieving the course objectives and should be conducted in the following years. Students who performed weakly in this assignment also demonstrated lower performance in all evaluations including by traditional means (p = 0.01, although there were no direct associations amongst the problem-based and the traditional evaluations (r <0.66. The students’ responses also reflected their readiness to perform more independent learning approaches, despite them expressing the lack of clear scope

  14. Generating enhanced site topography data to improve permeable pavement performance assessment methods - presentation

    Science.gov (United States)

    Permeable pavement surfaces are infiltration based stormwater control measures (SCM) commonly applied in parking lots to decrease impervious area and reduce runoff volume. Many are not optimally designed however, as little attention is given to draining a large enough contributin...

  15. Assessing artificial neural network performance in estimating the layer properties of pavements

    Directory of Open Access Journals (Sweden)

    Gloria Inés Beltran

    2014-07-01

    Full Text Available A major concern in assessing the structural condition of existing flexible pavements is the estimation of the mechanical properties of constituent layers, which is useful for the design and decision-making process in road management systems. This parameter identification problem is truly complex due to the large number of variables involved in pavement behavior. To this end, non-conventional adaptive or approximate solutions via Artificial Neural Networks – ANNs – are considered to properly map pavement response field measurements. Previous investigations have demonstrated the exceptional ability of ANNs in layer moduli estimation from non-destructive deflection tests, but most of the reported cases were developed using synthetic deflection data or hypothetical pavement systems. This paper presents further attempts to back-calculate layer moduli via ANN modeling, using a database gathered from field tests performed on three- and four-layer pavement systems. Traditional layer structuring and pavements with a stabilized subbase were considered. A three-stage methodology is developed in this study to design and validate an “optimum” ANN-based model, i.e., the best architecture possible along with adequate learning rules. An assessment of the resulting ANN model demonstrates its forecasting capabilities and efficiency in solving a complex parameter identification problem concerning pavements.

  16. Effectiveness of pavement-solar energy system – An experimental study

    International Nuclear Information System (INIS)

    Highlights: • We built a small-scale pilot project of pavement-solar energy utilization. • Design an automatic monitoring system to record the operating data. • The average heat absorptivity of pavement-solar energy is 37%. • The average thermal storage effectiveness of the system is 17%. - Abstract: A small-scale pilot project was built for the pavement-solar energy utilization in this paper. An automatic data acquisition system was designed to measure the effectiveness of the pavement solar energy system based on the operation data of 24 h a day in both summer and winter. Through 69 days (1656 h) of operation in summer, 2821 kW h of heat energy were stored in soil underground. In the transitional season, 4598 kW h of heat energy were taken out from soil during 104 days (2496 h) of operation in winter. The analysis showed that in summer, solar heat collection of asphalt pavement could effectively reduce 7 °C of its temperature. Under conditions of natural radiation, the average heat absorptivity of pavement was 37% and the average thermal storage effectiveness of the system was 17%. The electrical energy consumed by the system is only 11% of stored heat. During the winter, the asphalt pavement absorbs heat from underground soil which effectively increases its temperature, cutting 32% days of surface temperature below the freezing point. This not only save the energy for ice/snow removal but also mitigate associated safety risks

  17. Fuzzy logic inference-based Pavement Friction Management and real-time slippery warning systems: A proof of concept study.

    Science.gov (United States)

    Najafi, Shahriar; Flintsch, Gerardo W; Khaleghian, Seyedmeysam

    2016-05-01

    Minimizing roadway crashes and fatalities is one of the primary objectives of highway engineers, and can be achieved in part through appropriate maintenance practices. Maintaining an appropriate level of friction is a crucial maintenance practice, due to the effect it has on roadway safety. This paper presents a fuzzy logic inference system that predicts the rate of vehicle crashes based on traffic level, speed limit, and surface friction. Mamdani and Sugeno fuzzy controllers were used to develop the model. The application of the proposed fuzzy control system in a real-time slippery road warning system is demonstrated as a proof of concept. The results of this study provide a decision support model for highway agencies to monitor their network's friction and make appropriate judgments to correct deficiencies based on crash risk. Furthermore, this model can be implemented in the connected vehicle environment to warn drivers of potentially slippery locations. PMID:26914521

  18. Fuzzy logic inference-based Pavement Friction Management and real-time slippery warning systems: A proof of concept study.

    Science.gov (United States)

    Najafi, Shahriar; Flintsch, Gerardo W; Khaleghian, Seyedmeysam

    2016-05-01

    Minimizing roadway crashes and fatalities is one of the primary objectives of highway engineers, and can be achieved in part through appropriate maintenance practices. Maintaining an appropriate level of friction is a crucial maintenance practice, due to the effect it has on roadway safety. This paper presents a fuzzy logic inference system that predicts the rate of vehicle crashes based on traffic level, speed limit, and surface friction. Mamdani and Sugeno fuzzy controllers were used to develop the model. The application of the proposed fuzzy control system in a real-time slippery road warning system is demonstrated as a proof of concept. The results of this study provide a decision support model for highway agencies to monitor their network's friction and make appropriate judgments to correct deficiencies based on crash risk. Furthermore, this model can be implemented in the connected vehicle environment to warn drivers of potentially slippery locations.

  19. Re-use of stabilised flue gas ashes from solid waste incineration in cement-treated base layers for pavements

    DEFF Research Database (Denmark)

    Cai, Zuansi; Jensen, Dorthe Lærke; Christensen, Thomas Højlund;

    2003-01-01

    would teach during a 100-year period from a 0.5 m thick concrete stab exposed to water on one side. Leaching of the common ions Ca, Cl, Na and SO4 was increased 3-20 times from the specimens with chemically stabilised flue gas ashes from waste incineration. However, the quantities leached were still...... modest. These experiments suggest that FGA from waste incineration after Ferrox-treatment could be re-used in CTB without compromising the strength and teaching from the base layer.......Fly ash from coal-burning power plants has been used extensively as a pozzolan and fine filter in concrete for many years. Laboratory experiments were performed investigating the effect of substituting the coal-based fly ash with chemically stabilised flue gas ashes (FGA) from waste incineration...

  20. Re-use of stabilised flue gas ashes from solid waste incineration in cement-treated base layers for pavements.

    Science.gov (United States)

    Cai, Zuansi; Jensen, Dorthe L; Christensen, Thomas H; Bager, Dirch H

    2003-02-01

    Fly ash from coal-burning power plants has been used extensively as a pozzolan and fine filler in concrete for many years. Laboratory experiments were performed investigating the effect of substituting the coal-based fly ash with chemically stabilised flue gas ashes (FGA) from waste incineration. Two types of FGA were treated by the Ferrox-process, which removes the majority of the easily soluble salts in the FGA and provides binding sites for heavy metals in terms of ferrihydrite. Cubes of cement treated base layer materials containing 5% stabilised FGA were cast, sealed and cured for two weeks. Cylinders (diameter 100 mm, length 150 mm) were drilled from these cubes for tank leaching experiments. Duplicate specimens were subject to compression strength testing and to tank leaching experiments. The compressive strength of the CTB fulfilled the Danish requirements for CTB, i.e. strength more than 5 MPa after 7 days. The tank leaching tests revealed that leaching of heavy metals was not significantly affected by the use of chemically stabilised flue gas ashes from waste incineration. Assuming that diffusion controls the leaching process it was calculated that less than 1% of the metals would leach during a 100-year period from a 0.5 m thick concrete slab exposed to water on one side. Leaching of the common ions Ca, Cl, Na and SO4 was increased 3-20 times from the specimens with chemically stabilised flue gas ashes from waste incineration. However, the quantities leached were still modest. These experiments suggest that FGA from waste incineration after Ferrox-treatment could be re-used in CTB without compromising the strength and leaching from the base layer.

  1. Pavement Preservation for Elected Officials: The Inside Story of Pavement Deterioration

    OpenAIRE

    Olson, Jim

    2012-01-01

    This session is intended to provide elected officials and practitioners with an introduction to the concept of pavement preservation and its applicability within public agencies. Topics include definitions, budget planning, pavement life, road networks, alternative strategies, pavement distresses, guidelines and preservation treatments.

  2. Decreasing transactional distance in a Web-based course.

    Science.gov (United States)

    Pattillo, Robin E

    2007-01-01

    The Horizon Wimba online Web-conferencing voice system was used to facilitate dialogue and decrease transactional distance in a Web-based course. Small-group (Flashlight survey at the end of the semester. Anecdotal and survey responses indicated that discussion groups increased dialogue between faculty and students. PMID:17496503

  3. An overview of curriculum-based course timetabling

    DEFF Research Database (Denmark)

    Bettinelli, Andrea; Cacchiani, Valentina; Roberti, Roberto;

    2015-01-01

    In 2007, the Second International Timetabling Competition (ITC-2007) has been organized and a formal definition of the Curriculum-Based Course Timetabling (CB-CTT) problem has been given, by taking into account several real-world constraints and objectives while keeping the problem general. CB...

  4. Formative Evaluation of a Web-Based Course in Meteorology.

    Science.gov (United States)

    Phelps, Julia; Reynolds, Ross

    1999-01-01

    Describes the formative-evaluation process for the EuroMET (European Meteorological Education and Training) project, Web-Based university courses in meteorology that were created to address the education and training needs of professional meteorologists and students throughout Europe. Usability and interactive and multimedia elements are…

  5. A Methods-Based Biotechnology Course for Undergraduates

    Science.gov (United States)

    Chakrabarti, Debopam

    2009-01-01

    This new course in biotechnology for upper division undergraduates provides a comprehensive overview of the process of drug discovery that is relevant to biopharmaceutical industry. The laboratory exercises train students in both cell-free and cell-based assays. Oral presentations by the students delve into recent progress in drug discovery.…

  6. Web-Based Course Management and Web Services

    Science.gov (United States)

    Mandal, Chittaranjan; Sinha, Vijay Luxmi; Reade, Christopher M. P.

    2004-01-01

    The architecture of a web-based course management tool that has been developed at IIT [Indian Institute of Technology], Kharagpur and which manages the submission of assignments is discussed. Both the distributed architecture used for data storage and the client-server architecture supporting the web interface are described. Further developments…

  7. A Research-Based Development Economics Course for Undergraduates

    Science.gov (United States)

    Singh, Prakarsh; Guo, Hongye; Morales, Alvaro

    2015-01-01

    The authors present details of a research-based course in development economics taught at a private liberal arts college. There were three key elements in this class: teaching of applied econometrics, group presentations reviewing published and working papers in development economics, and using concepts taught in class to write an original…

  8. Automated management for pavement inspection system (AMPIS)

    Science.gov (United States)

    Chung, Hung Chi; Girardello, Roberto; Soeller, Tony; Shinozuka, Masanobu

    2003-08-01

    An automated in-situ road surface distress surveying and management system, AMPIS, has been developed on the basis of video images within the framework of GIS software. Video image processing techniques are introduced to acquire, process and analyze the road surface images obtained from a moving vehicle. ArcGIS platform is used to integrate the routines of image processing and spatial analysis in handling the full-scale metropolitan highway surface distress detection and data fusion/management. This makes it possible to present user-friendly interfaces in GIS and to provide efficient visualizations of surveyed results not only for the use of transportation engineers to manage road surveying documentations, data acquisition, analysis and management, but also for financial officials to plan maintenance and repair programs and further evaluate the socio-economic impacts of highway degradation and deterioration. A review performed in this study on fundamental principle of Pavement Management System (PMS) and its implementation indicates that the proposed approach of using GIS concept and its tools for PMS application will reshape PMS into a new information technology-based system providing a convenient and efficient pavement inspection and management.

  9. Impact of Overweight Traffic on Pavement Life Using Weigh-In-Motion Data and Mechanistic-Empirical Pavement Analysis

    OpenAIRE

    Wang, Hao; Zhao, Jingnan; Wang, Zilong

    2015-01-01

    The objective of this study is to evaluate the impact of overweight traffic on pavement life using mechanistic-empirical analysis approach. The state-of-practice mechanistic-empirical pavement design and analysis software (Pavement-ME) was used to predict pavement life under different traffic loading scenarios. Field performance data at the sites where the WIM data were collected were analyzed to estimate the pavement service life at field condition. The pavement structures considered in the ...

  10. Contributions of performance-graded asphalt to low temperature cracking resistance of pavements. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Loh, S.W.; Olek, J.

    1999-05-01

    The purpose of this research was to study and evaluate the role that asphalt cracking. As part of the Strategic Highway Research Program (SHRP) new specifications for asphalt binders were developed that are based on the performance of the material. The asphalt binder graded and specified according to these new performance-based specifications is called PG binder. These new specifications are commonly referred to as Superpave (Superior Performing Asphalt Pavement) binder specifications. A section of Interstate 64 in southern Indiana was experiencing severe low temperature cracking before it was reconstructed over the summers of 1995 and 1996. The binder used in the new pavement mixes was PG material. Dynamic Shear Rheometer (DSR) tests, Bending Beam Rheometer (BBR) tests, and viscosity tests were performed on this binder. Comparisons were made between test results obtained from the binders in the old pavement and the new pavement. All tests and comparisons were based on the Superpave binder specifications.

  11. Do sediment type and test durations affect results of laboratory-based, accelerated testing studies of permeable pavement clogging?

    Science.gov (United States)

    Nichols, Peter W B; White, Richard; Lucke, Terry

    2015-04-01

    Previous studies have attempted to quantify the clogging processes of Permeable Interlocking Concrete Pavers (PICPs) using accelerated testing methods. However, the results have been variable. This study investigated the effects that three different sediment types (natural and silica), and different simulated rainfall intensities, and testing durations had on the observed clogging processes (and measured surface infiltration rates) of laboratory-based, accelerated PICP testing studies. Results showed that accelerated simulated laboratory testing results are highly dependent on the type, and size of sediment used in the experiments. For example, when using real stormwater sediment up to 1.18 mm in size, the results showed that neither testing duration, nor stormwater application rate had any significant effect on PICP clogging. However, the study clearly showed that shorter testing durations generally increased clogging and reduced the surface infiltration rates of the models when artificial silica sediment was used. Longer testing durations also generally increased clogging of the models when using fine sediment (<300 μm). Results from this study will help researchers and designers better anticipate when and why PICPs are susceptible to clogging, reduce maintenance and extend the useful life of these increasingly common stormwater best management practices.

  12. Flexible pavement performance evaluation using deflection criteria

    Science.gov (United States)

    Wedner, R. J.

    1980-04-01

    Flexible pavement projects in Nebraska were monitored for dynamic deflections, roughness, and distress for six consecutive years. Present surface conditions were characterized and data for evaluating rehabilitation needs, including amount of overlay, were provided. Data were evaluated and factors were isolated for determining the structural adequacy of flexible pavements, evaluating existing pavement strength and soil subgrade conditions, and determining overlay thickness requirements. Terms for evaluating structural condition for pavement sufficiently ratings were developed and existing soil support value and subgrade strength province maps were evaluated.

  13. Structural Evaluation for Maputo Airport Pavement

    Institute of Scientific and Technical Information of China (English)

    Jose F.R.Diogo; LU Yang; ZHANG Hua

    2007-01-01

    Maputo Airport was initially constructed to serve mixed traffic of light and medium aircrafts. With its opening to heavier aircrafts such as B727, DC10, Airbus 340, etc. , structural improvements have become necessary. For this purpose, structural evaluation were described and performed using falling weight deflectometer. Results show that while subgrade response to loads appears more consistent with depth, surface layer of the pavement is significantly influenced by the layer thickness as well as mechanical properties of pavement materials. Load magnitude also affects pavement performance. But loading conditions show an equivalent or even greater influence on pavement performance.

  14. Recyclability of Concrete Pavement Incorporating High Volume of Fly Ash

    Directory of Open Access Journals (Sweden)

    Isamu Yoshitake

    2015-08-01

    Full Text Available Recyclable concrete pavement was made from fly ash and crushed limestone sand and gravel as aggregates so that the concrete pavement could be recycled to raw materials for cement production. With the aim to use as much fly ash as possible for the sustainable development of society, while achieving adequate strength development, pavement concrete having a cement-replacement ratio of 40% by mass was experimentally investigated, focusing on the strength development at an early age. Limestone powder was added to improve the early strength; flexural strength at two days reached 3.5 MPa, the minimum strength for traffic service in Japan. The matured fly ash concrete made with a cement content of 200 kg/m3 achieved a flexural strength almost equal to that of the control concrete without fly ash. Additionally, Portland cement made from the tested fly ash concrete was tested to confirm recyclability, with the cement quality meeting the Japanese classification of ordinary Portland cement. Limestone-based recyclable fly ash concrete pavement is, thus, a preferred material in terms of sustainability.

  15. Monitoring pavement response and performance using in-situ instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.H.; Bilyeu, J.; Hugo, F.

    1999-07-01

    The purpose of this paper is to present the effectiveness of in-situ instrumentation on diagnosing the pavement layer conditions under full-scale accelerated traffic loading. The test section is an in-service pavement (US281) in Jacksboro, Texas. Multi-Depth Deflectometers (MDDs) are used to measure both permanent deformations and transient deflections, caused by accelerated traffic loading and Falling Weight Deflectometers (MDDs) are used to measure both permanent deformations and transient deflections, caused by accelerated traffic loading and Falling Weight Deflectometer (FWD) tests. Four different FWD loads of 25, 40, 52, and 67 kN were applied in close proximity to the MDDs at various traffic loading intervals to determine pavement conditions. It was found that the majority of rutting occurred in the newly recycled asphalt mix. The aged ({gt}40 years) underlying base and subgrade layers contributed less than 30% to overall rutting. Only the top recycled Asphalt layer underwent notable deterioration due to traffic loading. Up to 1.5 million axle repetitions, the test pad responded to FWD load almost linearly, not only over the whole pavement system but also within individual layers. However, under higher FWD loads, the percentage of total deflection contributed by the subgrade increased.

  16. An Approach for Nonlinear Fatigue Damage Evaluation in Asphalt Pavements

    Science.gov (United States)

    Rajbongshi, Pabitra; Thongram, Sonika

    2016-08-01

    Fatigue due to vehicular loads is one of the primary distress mechanisms in asphalt pavements. It happens primarily due to deterioration in asphalt material with load repetitions. Degradation of asphalt material may be evaluated using different parameters. In view of degradation, the incremental damage in a given pavement section would be different for different repetitions, even with same loadings. Therefore, the damage progression becomes nonlinear with repetitions. Accounting such nonlinearity in damage accumulation, and based on different damage evaluation parameters, this paper presents an equivalent approach for fatigue damage evaluation in asphalt pavements. Traditional fatigue equation adopted in mechanistic-empirical pavement design has been used in the present work. Four different criteria, namely number of load repetitions, asphalt stiffness reduction, strain enhancement and fatigue life reduction with repetitions are considered for damage estimation. The proposed approach could estimate same value of nonlinear damage, irrespective of the criteria used. The simplest form of criterion i.e. the number of load repetitions can be used for fatigue performance evaluation. Probabilistically, the damage propagation is also correlated and assessed with the failure probability.

  17. 基于分形理论评价沥青路面微观构造%Valuation of Microscopic Structure of Asphalt Pavement Based on Fractal Theory

    Institute of Scientific and Technical Information of China (English)

    李智; 刘涛

    2013-01-01

    鉴于路面微观构造对抗滑性能有着重要的影响,选取4种不同材质的石料分别成型试样,借助散射法-激光纹理仪测量各试样在不同磨损状况下的微观构造,运用分形理论的盒子计数法,通过MATLAB编程实现对试样在不同磨损状况下分维数的计算.试验结果表明:花岗岩的分维数水平和耐磨光性能均较优,石灰岩的耐磨光性能差,该评价方法可以准确评价路面的微观纹理复杂程度,并能有效预测路面的长期抗滑性能.%As pavement micro-structure has an important influence on skid resistance condition,this paper chooses 4 different road stones and then prepared samples,with scattering-laser texture meter,The microscopic texture of the samples curve was measured in different wear condition,by the fractal dimension of the box theory counting method,the samples curve was fast calculated by use MATLAB programming in different wear condition fractal dimension,The results show that sample A have better fractal dimension results and wear resistance,sample C have less wear resistance.The evaluation method can accurately evaluate the micro-texture of pavement,and the pavement long term skid resistance condition can be predicted effectively.

  18. 工业废渣路面基层材料试验研究%An Experimental Study on Pavement Base Materials with Industrial Wastes

    Institute of Scientific and Technical Information of China (English)

    高伏良; 黄永强; 李飞; 孙超林; 黄大成; 马韧

    2012-01-01

    Portland cement, cement-fly ash, and lime-fly ash stabilized pavement base materials using steel slag and crushed stone as aggregate was prepared. Experiments on unconfined compressive strength, splitting strength, compressive resilient modulus, and scour-resistance were conducted. Steel slag shows superior performance as aggregate than macadam. Materials using steel slag show superior strength than materials using crushed stone. While cement stabilized steel slag shows the highest unconfined compressive strength, lime-fly ash stabled steel slag shows the highest splitting strength. Resilient modulus of base materials with cement-fly ash keeps rising in 180d curing age, while resilient modulus of base materials with cement only exhibits little change. Resilient modulus of lime-fly ash stabilized steel slag is significantly higher than other materials. Scour-resistance of cement stabled steel slag is better than that of cement stabled crushed stone. However, influence of aggregate type-on scour-resistance is insignificant for both cement-fly ash~and lime-fly ash stabilized base materials.%以钢渣、碎石为集料,通过实验室试验研究了水泥、水泥粉煤灰、石灰粉煤灰稳定路面基层材料的无侧限抗压强度、劈裂强度、抗压回弹模量和抗冲刷性能.结果表明,钢渣作为公路基层集料具有较碎石更为良好的性能.钢渣作为集料的基层材料强度高于碎石作为集料的基层材料;用水泥稳定钢渣可获得相对高的无侧限抗压强度,用石灰粉煤灰稳定钢渣获得相对高的劈裂强度.掺加粉煤灰的基层材料在180 d龄期间抗压回弹模量保持增长,水泥稳定基层材料90 d以后抗压回弹模量无明显增长.石灰粉煤灰稳定钢渣的回弹模量显著高于其他基层材料.水泥稳定钢渣抗冲刷性较水泥稳定碎石好,水泥粉煤灰与石灰粉煤灰稳定类用钢渣代替碎石作为集料对冲刷性能影响不明显.

  19. Gender-based performance differences in an introductory physics course

    Science.gov (United States)

    McKinnon, Mark Lee

    Cognitive research has indicated that the difference between males and females is negligible. Paradoxically, in traditionally-taught college level introductory physics courses, males have outperformed females. UC Davis' Physics 7A (the first class of a three-quarter Introduction to Physics sequence for Life-Science students), however, counters this trend since females perform similarly to males. The gender-based performance difference within the other two quarters (Physics 7B & 7C) of the radically restructured, active-learning physics sequence still echo the traditionally-taught courses. In one experiment, I modified the laboratory activity instructions of the Physics 7C course to encourage further group interaction. These modifications did not affect the gender-based performance difference. In a later experiment, I compared students' performance on different forms of assessment for certain physics concepts during the Physics 7C course. Over 500 students took weekly quizzes at different times. The students were given different quiz questions on the same topics. Several quiz questions seemed to favor males while others were more gender equitable. I highlighted comparisons between a few pairs of questions that assessed students' understanding of the same physical concept. Males tended to perform better in responding to questions that seemed to require spatial visualization. Questions that required greater understanding of the physical concept or scientific model were more gender neutral.

  20. Design and Model Test of Cement Concrete Pavement Slab Based on Phase Change and Temperature Control%相变控温水泥混凝土路面板设计及模型试验

    Institute of Scientific and Technical Information of China (English)

    高英力; 胡柏学; 贺敬; 杨文剑

    2011-01-01

    Based on the phase change energy storage material and functionally-graded material design method, the conventional structure of cement concrete pavement slab was designed for enhancing the function of anti-freezing and wear-resistance, and the model test of pavement slab was carried out. The step cooling test method was adopted to select the composite phase change material, and then it was placed in the high-strength seamless steel pipe. The size of the formed cement concrete pavement slab model was 500 mm × 400 mm × 80 mm. Anti-freezing and wearresistance property test of the model was carried out. Results indicate that phase change temperature point of the selected phase change material is about 5 ℃, and at the point, the liquidsolid phase transition happens to reject heat which can play better ice-melting effect and delay or control the low-temperature freezing phenomena of the pavement slab model surface. The wearresistance of the pavement slab surface material is excellent and its 28-day wear rate is only 51.9% of the standard limited value. The reinforced role of steel pipe in the phase change function layer can prevent the problem of inconsistent volume deformation between the main structure layer and surface layer and also can enhance interface stability.%引入相变储能材料及梯度功能材料设计方法,对传统水泥混凝土路面板结构进行防冻、耐磨功能设计,开展路面板模型试验研究.采取步冷试验方法,将优选出的复合相变储能材料封装入高强度无缝钢管中,制成500 mm×400 mm×80 mm的水泥混凝土路面板模型,进行模型的防冻性能和耐磨性能试验.结果表明:优选的相变材料体系相变温度点可控制在5℃左右,并产生液-固相变过程,放出热量,起到了较好的融冰效果,延缓或控制了路面板模型表面的低温冰冻现象;表面层材料耐磨性优良,28 d磨耗率仅为标准限值的51.9%;相变功能层中钢管的加筋作用可防止主

  1. Preliminary evaluation of the lifecycle costs and market barriers of reflective pavements; TOPICAL

    International Nuclear Information System (INIS)

    , which we call the chipping and aggregate methods, and calculated their potential life cycle costs. By analyzing the potential for increased pavement durability resulting from these conceptual approaches, we then estimated the incremental costs that would allow them to be cost-effective compared to conventional AC. For our example case of Los Angeles, we found that those allowable incremental costs range from less than dollar 1 to more than dollar 11 per square yard (dollar 1 to dollar 13 per square meter) depending on street type and the condition of the original pavement. Finally, we evaluated the main actors in the pavement market and the existing and potential market barriers associated with reflective pavements. Apart from situations where lifecycle costs are high compared to conventional AC, all reflective paving technologies face a cultural barrier based on the belief that black is better. For PCC, high first costs were found to be the most significant economic barrier, particularly where agencies are cons trained by first cost. Lack of developer standards was found to be a significant institutional barrier to PCC since developers are often not held accountable for the long-term maintenance of roads after initial construction, which creates a misplaced incentive to build low first-cost pavements. PCC also faces site-specific barriers such as poorly compacted base soils and proximity to areas of frequent utility cutting

  2. Preliminary evaluation of the lifecycle costs and market barriers of reflective pavements

    Energy Technology Data Exchange (ETDEWEB)

    Ting, M.; Koomey, J.G.; Pomerantz, M.

    2001-11-21

    , which we call the chipping and aggregate methods, and calculated their potential life cycle costs. By analyzing the potential for increased pavement durability resulting from these conceptual approaches, we then estimated the incremental costs that would allow them to be cost-effective compared to conventional AC. For our example case of Los Angeles, we found that those allowable incremental costs range from less than dollar 1 to more than dollar 11 per square yard (dollar 1 to dollar 13 per square meter) depending on street type and the condition of the original pavement. Finally, we evaluated the main actors in the pavement market and the existing and potential market barriers associated with reflective pavements. Apart from situations where lifecycle costs are high compared to conventional AC, all reflective paving technologies face a cultural barrier based on the belief that black is better. For PCC, high first costs were found to be the most significant economic barrier, particularly where agencies are cons trained by first cost. Lack of developer standards was found to be a significant institutional barrier to PCC since developers are often not held accountable for the long-term maintenance of roads after initial construction, which creates a misplaced incentive to build low first-cost pavements. PCC also faces site-specific barriers such as poorly compacted base soils and proximity to areas of frequent utility cutting.

  3. Numerical Simulation of Moving Load on Concrete Pavements

    Directory of Open Access Journals (Sweden)

    Lajčáková Gabriela

    2015-06-01

    Full Text Available The knowledge of the development with time of the strain and stress states in pavement structures is needed in the solution of various engineering tasks as the design fatigue lifetime reliability maintenance and structure development. The space computing model of the truck TATRA 815 is introduced. The pavement computing model is created in the sense of Kirchhof theory of the thin slab on elastic foundation. The goal of the calculation is to obtain the vertical deflection in the middle of the slab and the time courses of vertical tire forces. The equations of motion are derived in the form of differential equations. The assumption about the shape of the slab deflection area is adopted. The equations of the motion are solved numerically in the environment of program system MATLAB. The dependences following the influence of various parameters (speed of vehicle motion, stiffness of subgrade, slab thickness, road profile on the pavement vertical deflections and the vertical tire forces are introduced. The results obtained from the plate computing model are compared with the results obtained by the FEM analysis. The outputs of the numerical solution in the time domain can be transformed into a frequency domain and subsequently used to solve various engineering tasks.

  4. Water quality and quantity assessment of pervious pavements performance in experimental car park areas

    OpenAIRE

    Sañudo Fontaneda, Luis Ángel; Charlesworth, Susanne M.; Castro Fresno, Daniel; Andrés Valeri, Valero Carlos Alessio; Rodríguez Hernández, Jorge

    2014-01-01

    Pervious pavements have become one of the most used sustainable urban drainage system (SUDS) techniques in car parks. This research paper presents the results of monitoring water quality from several experimental car park areas designed and constructed in Spain with bays made of interlocking concrete block pavement, porous asphalt, polymer-modified porous concrete and reinforced grass with plastic and concrete cells. Moreover, two different sub-base materials were used (limestone aggregates a...

  5. Applicability Analysis of Existing Widening Pavement Structure%旧路加宽路面结构适用性分析

    Institute of Scientific and Technical Information of China (English)

    李春明

    2011-01-01

    应用弹性层状体系理论对路面结构在不均匀沉降条件下的附加应力状况进行了计算。计算结果表明,在不均匀沉降位移作用下,降低基层材料模量,有利于路面各层合理受力;半刚性基层容易引起附加应力过大而产生结构性破坏;柔性基层更适合在旧路加宽路面结构中使用。%Additional stress of pavement structure under differential settlement is calculated with elastic layered system theory.The result shows that under the effect of differential settlement displacement,decreasing modulus of base course material is helpful for reasonable stress of each layer;semi-rigid base course easily leads to large additional stress which could cause structure damage;flexible base course is moreapplicable for existing widening pavement structure.

  6. Stress Analysis and Determination of Effective k-value for Rigid Pavement

    Directory of Open Access Journals (Sweden)

    Kundan Meshram

    2013-03-01

    Full Text Available EverFE is a user-friendly 3D finite-element analysis tool for simulating the response of jointed plain concrete pavement (JPCP systems to axle loads and environmental effects. EverFE is useful for both concrete pavement researchers and designers who must perform either complex nonlinear or simple linear stress analyses of JPCP.With help of this develop any type of model of rigid pavement considering practical condition thus getting more accurate and advance analysis for rigid pavement. It can also determine effective k-values for different combination of granular sub-base and dry lean concrete. A comparative study is done for two types of loading i.e. single and tandem axle. Edge and Corner stresses are also calculated for Class-AA of loading. Also calculate moment and shear force transfer by dowel bar by EverFE.

  7. Innovative Data Mining Based Approaches for Life Course Analysis

    OpenAIRE

    Ritschard, Gilbert; Gabadinho, Alexis; Mueller, Nicolas Séverin; Studer, Matthias

    2007-01-01

    This communication presents a just starting research project aiming at exploring the possibilities of resorting to data-mining-based methods in personal life course analysis. The project has also a socio-demographic goal, namely to gain new insights on how socio-demographic, familial, educational and professional events are entwined, on what are the characteristics of typical Swiss life trajectories and on changes in these characteristics over time. Methods for analyzing personal event histor...

  8. Modelling Flexible Pavement Response and Performance

    DEFF Research Database (Denmark)

    Ullidtz, Per

    This textbook is primarily concerned with models for predicting the future condition of flexible pavements, as a function of traffic loading, climate, materials, etc., using analytical-empirical methods.......This textbook is primarily concerned with models for predicting the future condition of flexible pavements, as a function of traffic loading, climate, materials, etc., using analytical-empirical methods....

  9. Numerical Simulation of Tire-Pavement Interaction

    NARCIS (Netherlands)

    Srirangam, S.K.

    2015-01-01

    Good skid resistance of a pavement surface is essential for road safety. Loss of skid resistance can lead to property damage and loss of lives. Ever increasing need of driver safety poses challenges to the highway authorities to evaluate pavement conditions even more precisely under different condit

  10. Pervious Pavement System Evaluation-Paper

    Science.gov (United States)

    The use of a pervious pavement can be effective as a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete paver systems as a type of porous pavement. Although the pavers are impermeable, the spaces between the pave...

  11. 基于模糊综合评价的沥青路面施工质量过程控制模型%Asphalt pavement construction quality process control model based on the fuzzy synthetic evaluation

    Institute of Scientific and Technical Information of China (English)

    李海滨

    2012-01-01

    There is a problem of control delay in the asphalt pavement construction quality control and if the quality control is effectively achieved it can ensure the engineering quality. The index system model of quality process control is proposed through analyzing the quality influence factors of the construction which the indexes are selected from materials, machines, staffs and technologies, then the right weight of pivotal index is valuated based on the principle of improved Analytic Hierarchy Process. It can realize multipoint control and real-time monitoring in the asphalt pavement construction process using fuzzy synthetic evaluation. The example of index of " staff" proves that the asphalt pavement construction quality control model based on the fuzzy synthetic evaluation is feasible and it can be used in the practical engineering.%沥青路面施工质量控制具有一定的滞后性,有效实现施工质量过程控制可以确保良好的工程质量.通过分析沥青路面施工过程中的质量影响因素,从材料、设备、人员、工艺4个方面选择质量控制指标,构建过程控制指标体系,并采用改进层次分析法确定各指标权重值.采用模糊综合评价方法对沥青路面施工质量过程实现分阶段的多点控制,实现有效实时的施工质量监控.人员指标过程控制实例证明,基于模糊综合评价的沥青路面施工质量控制模型是可行的,可以在实际工程中进行运用.

  12. Research on Rutting Resistance of Asphalt Pavement Structure%沥青路面结构抗车辙的研究

    Institute of Scientific and Technical Information of China (English)

    高立波

    2011-01-01

    结合对某高速公路路面车擞近十年的跟踪检测和试验,从新的角度认识路面结构因素对路面车辙的影响,提出了路面结构组合设计原则和联结层设计理念及结构抗车辙措施。%Combined with the almost ten years of tracing inspection and test about an expressway pavement rutting, the influence of pavement structure on pavement rutting is recognized from a new angle. The design principle of pavement structure of pavement combination, design concept of binder course and rutting resistance measures are proposed.

  13. 水泥混凝土路面填缝料疲劳试验方法研究%Research on Fatigue Test Methods for Joint Sealing Materials for Cement Concrete Pavement

    Institute of Scientific and Technical Information of China (English)

    王宝松; 王进勇; 龙丽琴

    2012-01-01

    水泥混凝土路面填缝料在实际应用中,受气候、机械外力作用产生疲劳老化,使用寿命下降.填缝料疲劳导致地表水渗入基层是水泥混凝土路面破坏的重要原因之一.现有填缝料评价体系中无体现疲劳性能的评价指标.基于对现有水泥混凝土路面接缝料的力学研究和室内试验,提出适合于水泥混凝土路面填缝料疲劳性能检测的试验方法和仪器,其对于水泥混凝土路面填缝料的研究及应用具有重要意义.%Joint sealing materials for cement concrete pavement in practical application produce fatigue aging under effect of climate and mechanical force and the service life decreases. Penetration of surface water into base course caused by fatigue of joint sealing materials is one of important reasons for damage to cement concrete pavement. Existing evaluation system for joint sealing materials has no evaluation indices for fatigue performance. On the basis of mechanical research and indoor test for joint sealing materials for cement concrete pavement, this paper proposes test methods and instruments suitable for detection of fatigue performance of joint sealing materials for cement concrete pavement, which show importance significance for research and application of joint sealing materials for cement concrete pavement.

  14. Pavement response to vehicular loads: a mechanistic approach involving nondestructive evaluation techniques

    Science.gov (United States)

    Kennedy, James C., Jr.

    1996-11-01

    The need for effective design in the nation's highways is greater now, more than ever, due to shrinking funds for new construction and rehabilitation/maintenance practices and the need to preserve the lands that are not now part of the roadway system. Most of the nation's highways were constructed within the last 30 years and many of these are due for significant rehabilitation and even reconstruction. Thus, the need to infuse robust design methods into these rehabilitation and reconstruction strategies is paramount. Currently, methods for cost allocation for pavement rehabilitation/maintenance activities and pavement management estimations are based on empirical and semi- empirical founded predictions that come up short, particularly when the roadway i subjected to multi-axle, heavy weight vehicles. Additionally, materials currently used int he construction of the pavement structure do not always behave in an elastic manner and the ability to predict the pavement response in the presence of other than elastic material behavior is essential. Finally, prediction of pavement states of distress based on empirical methods and elastic material behavior are inadequate, particularly when heavy weight vehicular traffic is involved. This paper includes descriptions of the overall methodology for pavement design and the unique requirements for the design and implementation of the structural and environmental sensing elements. Description of the mechanistic aspects in the software for the structural and material models is discussed and comparison of predicted and field measured results are presented.

  15. Improving Rutting Resistance of Pavement Structures Using Geosynthetics: An Overview

    Directory of Open Access Journals (Sweden)

    Sina Mirzapour Mounes

    2014-01-01

    Full Text Available A pavement structure consists of several layers for the primary purpose of transmitting and distributing traffic loads to the subgrade. Rutting is one form of pavement distresses that may influence the performance of road pavements. Geosynthetics is one type of synthetic materials utilized for improving the performance of pavements against rutting. Various studies have been conducted on using different geosynthetic materials in pavement structures by different researchers. One of the practices is a reinforcing material in asphalt pavements. This paper intends to present and discuss the discoveries from some of the studies on utilizing geosynthetics in flexible pavements as reinforcement against permanent deformation (rutting.

  16. Improving rutting resistance of pavement structures using geosynthetics: an overview.

    Science.gov (United States)

    Mirzapour Mounes, Sina; Karim, Mohamed Rehan; Khodaii, Ali; Almasi, Mohammad Hadi

    2014-01-01

    A pavement structure consists of several layers for the primary purpose of transmitting and distributing traffic loads to the subgrade. Rutting is one form of pavement distresses that may influence the performance of road pavements. Geosynthetics is one type of synthetic materials utilized for improving the performance of pavements against rutting. Various studies have been conducted on using different geosynthetic materials in pavement structures by different researchers. One of the practices is a reinforcing material in asphalt pavements. This paper intends to present and discuss the discoveries from some of the studies on utilizing geosynthetics in flexible pavements as reinforcement against permanent deformation (rutting).

  17. Improving rutting resistance of pavement structures using geosynthetics: an overview.

    Science.gov (United States)

    Mirzapour Mounes, Sina; Karim, Mohamed Rehan; Khodaii, Ali; Almasi, Mohammad Hadi

    2014-01-01

    A pavement structure consists of several layers for the primary purpose of transmitting and distributing traffic loads to the subgrade. Rutting is one form of pavement distresses that may influence the performance of road pavements. Geosynthetics is one type of synthetic materials utilized for improving the performance of pavements against rutting. Various studies have been conducted on using different geosynthetic materials in pavement structures by different researchers. One of the practices is a reinforcing material in asphalt pavements. This paper intends to present and discuss the discoveries from some of the studies on utilizing geosynthetics in flexible pavements as reinforcement against permanent deformation (rutting). PMID:24526919

  18. Immersive Interprofessional Education Using an Evidence-Based Practice Course.

    Science.gov (United States)

    Hale, LaDonna S; DiLollo, Anthony

    2016-09-01

    Beyond medical knowledge and clinical skills, physician assistant curricula must include instruction in collaborative, interprofessional, patient-centered, evidence-based practice (EBP). Development and implementation of interprofessional education (IPE) are challenging. This article describes a replicable model for an interprofessional graduate-level course that incorporates both exposure and immersion, allowing students to develop and demonstrate the Interprofessional Education Collaborative's 38 core competencies for interprofessional, collaborative decision making and problem solving while also acquiring functional skills in EBP. Pre- and postcourse surveys demonstrated both improved student self-confidence with EBP skills and appreciation for an interprofessional approach to patient care. Barriers to, and facilitators of, development and implementation of IPE courses, as well as effective IPE strategies and tools, are discussed. PMID:27548762

  19. Study on Influence Factors of Anti-shear Performance of High Grade Asphalt Concrete Pavement%高等级沥青混凝土路面抗剪性能影响因素研究

    Institute of Scientific and Technical Information of China (English)

    王志强

    2014-01-01

    Based on the multilayered elastic system theory and the GAMES software,considering the thickness of pavement structure courses,the stiffness and the interface condition,the paper analyzed the change law of anti-shear performance of the asphalt pavement.The results show that:the effect of the thickness of the surface course and the base course on the asphalt pavement is insignificant,so it is a waste of cost to increase the thickness of the surface course and the base course to enhance the shearing capability;the shear stress peak value in the surface course would be reduced by increasing the modulus of base course,but the change is not obvious,which indicates that it does little to promote the anti-shear performance by increasing the modulus of base course;the more the modulus ratio between the wearing course and the mid-course,the greater the shear stress peak value in the surface course,which can be ob-viously seen;the shear stress peak value in the surface course would be reduced by the decrease of inter-facial bonding performance.%运用多层弹性体系理论,以 GAMES 软件为力学分析工具,考虑路面结构层厚度、基面层模量及层间状态等因素,分析沥青路面抗剪性能的变化规律。结果表明:沥青路面剪应力峰值受面层厚度和基层厚度影响不明显,通过增加面层厚度和基层厚度提高路面抗剪性能加重了经济成本,收效甚微;面层内剪应力峰值随基层模量增加而减小,但变化不明显,说明增加基层模量对沥青路面抗剪性能的提高作用不大;上面层与中面层模量比越大,上面层内剪应力峰值越大,且这种影响较为明显;在层间粘结减弱的过程中,面层内最大剪应力峰值随之减小。

  20. Aircraf landing gear design in respect of pavement design

    OpenAIRE

    Fabre, C.; ALBIN, A; Balay, Jean Maurice

    2009-01-01

    This paper considers the close relationship between aircraft landing gear (LG) and pavement design in respect of airfield pavement compatibility. In pavement design and analysis, we usually deal with pavement structures, materials and design thickness procedure but rarely aircraft LG design This paper emphasizes key drivers, which must be considered for new aircraft LG design to achieve aircraft pavement compatibility. Several parameters such as number & size of wheels, type of gear, brakes, ...

  1. Automatic Road Pavement Assessment with Image Processing: Review and Comparison

    Directory of Open Access Journals (Sweden)

    Sylvie Chambon

    2011-01-01

    Full Text Available In the field of noninvasive sensing techniques for civil infrastructures monitoring, this paper addresses the problem of crack detection, in the surface of the French national roads, by automatic analysis of optical images. The first contribution is a state of the art of the image-processing tools applied to civil engineering. The second contribution is about fine-defect detection in pavement surface. The approach is based on a multi-scale extraction and a Markovian segmentation. Third, an evaluation and comparison protocol which has been designed for evaluating this difficult task—the road pavement crack detection—is introduced. Finally, the proposed method is validated, analysed, and compared to a detection approach based on morphological tools.

  2. A STEM-Based, High School Aviation Course

    Science.gov (United States)

    Surra, Alex; Litowitz, Len S.

    2015-01-01

    The authors describe a vocational training course that was developed to give more than just an overview of how aircraft work, or a course on how to fly. This training course was a half-year course in aviation technology. Powered flight is an area of interest for many students, and the intent of creating a curriculum rich with science, technology,…

  3. Influential Factors on Deicing Performance of Electrically Conductive Concrete Pavement

    Institute of Scientific and Technical Information of China (English)

    TANG Zuquan; QIAN Jueshi; LI Zhuoqiu; WU Chuanming

    2006-01-01

    The deicing experiment of carbon fiber reinforced electrically conductive concrete (CFRC) slab was conducted in laboratory at first, then the deicing process of CFRC pavement was analyzed by means of finite element method (FEM). At last, based on the energy conservation law and the computing results of finite element method, the influential factors including the setting of electric heating layer, environmental temperature, the thickness of ice, material parameters, and deicing power on deicing performance and energy consumption were discussed.

  4. Texture friction relationship: from texture empirical decomposition to pavement friction

    OpenAIRE

    Kane, Malal; RADO, Zoltan; CEREZO, Véronique; TIMMONS, Andrew; DO, Minh Tan

    2014-01-01

    This work investigates the friction-texture relationship: starting from a decomposition method of the pavement texture that is part of a new signal processing so called “Huang Hilbert Transformation” to texture parameters-friction relation. This method allows empirical decomposition of the texture profile to a set of basic profiles in a limited number, so called “Intrinsic Mode Functions” or IMF. From the obtained IMFs, a set of four new functions so called “Base...

  5. An inquiry-based course in nano-photonics

    Science.gov (United States)

    Broadbridge, Christine; Calvert, Jodi; Donnelly, Judith; Garofano, Jacquelynn; Massa, Nicholas

    2010-08-01

    We developed a curriculum to introduce nanotechnology and photonics concepts to community college students enrolled in a program designed to attract and retain students in technology associate degree programs. Working with the Center for Research on Interface Structures and Phenomena, an NSF Materials Research Science and Engineering Center, and the PHOTON projects, funded by the Advanced Technological Education program of NSF, we developed hands-on, inquiry-based activities to address the course goals: improve critical thinking, introduce science and technology concepts common to technology programs and provide opportunity to practice math skills in context.

  6. Video-based problems in introductory mechanics physics courses

    International Nuclear Information System (INIS)

    Introductory mechanics physics courses at the transition from school to university are a challenge for students. They are faced with an abrupt and necessary increase of theoretical content and requirements on their conceptual understanding of phyiscs. In order to support this transition we replaced part of the mandatory weekly theory-based paper-and-pencil problems with video analysis problems of equal content and level of difficulty. Video-based problems (VBP) are a new problem format for teaching physics from a linked sequence of theoretical and video-based experimental tasks. Experimental tasks are related to the well-known concept of video motion analysis. This introduction of an experimental part in recitations allows the establishment of theory–experiment interplay as well as connections between physical content and context fields such as nature, technique, everyday life and applied physics by conducting model-and context-related experiments. Furthermore, laws and formulas as predominantly representative forms are extended by the use of diagrams and vectors. In this paper we give general reasons for this approach, describe the structure and added values of VBP, and show that they cover a relevant part of mechanics courses at university. Emphasis is put on theory–experiment interplay as a structural added value of VBP to promote students' construction of knowledge and conceptual understanding. (paper)

  7. The Impact of Course Length on Online Numeric-Based Course Grades

    Science.gov (United States)

    Mensch, Scott

    2013-01-01

    When offering online classes, it is necessary to ensure that all course material and objectives will be covered and learners will be successful in the course. This becomes especially important when the same class material and objectives are offered in a three-, five-, and fourteen-week format. This paper outlines the difficulty of delivering…

  8. A Module-Based Environmental Science Course for Teaching Ecology to Non-Majors

    Science.gov (United States)

    Smith, Geoffrey R.

    2010-01-01

    Using module-based courses has been suggested to improve undergraduate science courses. A course based around a series of modules focused on major environmental issues might be an effective way to teach non-science majors about ecology and ecology's role in helping to solve environmental problems. I have used such a module-based environmental…

  9. Nonlinear Responses of a Two Dimensional Vehicle-pavement System

    Directory of Open Access Journals (Sweden)

    Shaohua Li

    2013-09-01

    Full Text Available The vehicle and pavement are usually investigated separately in vehicle dynamics and pavement dynamics. In this work, a new research scheme is proposed to link the vehicle and pavement model by tire loads and compute the nonlinear dynamic responses by analytical methods. A two-DOF nonlinear vehicle and a Bernoulli-Euler beam on a nonlinear elastic foundation with two simply supported ends compose the nonlinear vehicle-pavement system. The nonlinear tire loads are analytically gained using the averaging method. Then the nonlinear vibration equation of the pavement is obtained using Galerkin method and solved using the multiple scales method. The theoretical solutions are verified by numerical results and the effects of system parameters on pavement vibration are also studied. It is found that the pavement responses excited by tire loads attenuate quickly and small pavement mass, large foundation damping or foundation stiffness may decrease the pavement vibration.

  10. Development of a fiber optic pavement subgrade strain measurement system

    Science.gov (United States)

    Miller, Craig Emerson

    2000-11-01

    This dissertation describes the development of a fiber optic sensing system to measure strains within the soil subgrade of highway pavements resulting from traffic loads. The motivation to develop such a device include improvements to: (1)all phases of pavement design, (2)theoretical models used to predict pavement performance, and (3)pavement rehabilitation. The design of the sensing system encompasses selecting an appropriate transducer design as well as the development of optimal optical and demodulation systems. The first is spring based, which attempts to match its spring stiffness to that of the soil-data indicate it is not an optimal transducer design. The second transducer implements anchoring plates attached to two telescoping tubes which allows the soil to be compacted to a desired density between the plates to dictate the transducer's behavior. Both transducers include an extrinsic Fabry- Perot cavity to impose the soil strains onto a phase change of the optical signal propagating through the cavity. The optical system includes a low coherence source and allows phase modulation via path length stretching by adding a second interferometer in series with the transducer, resulting in a path matched differential interferometer. A digitally implemented synthetic heterodyne demodulator based on a four step phase stepping algorithm is used to obtain unambiguous soil strain information from the displacement of the Fabry-Perot cavity. The demodulator is calibrated and characterized by illuminating the transducer with a second long coherence source of different wavelength. The transducer using anchoring plates is embedded within cylindrical soil specimens of varying soil types and soil moisture contents. Loads are applied to the specimen and resulting strains are measured using the embedded fiber optic gage and LVDTs attached to the surface of the specimen. This experimental verification is substantiated using a finite element analysis to predict any differences

  11. Promoting Inquiry-Based Teaching in Laboratory Courses: Are We Meeting the Grade?

    OpenAIRE

    Beck, Christopher; Butler, Amy; Burke da Silva, Karen

    2014-01-01

    Over the past decade, repeated calls have been made to incorporate more active teaching and learning in undergraduate biology courses. The emphasis on inquiry-based teaching is especially important in laboratory courses, as these are the courses in which students are applying the process of science. To determine the current state of research on inquiry-based teaching in undergraduate biology laboratory courses, we reviewed the recent published literature on inquiry-based exercises. The majori...

  12. A "Medical Physics" Course Based Upon Hospital Field Experience

    Science.gov (United States)

    Onn, David G.

    1972-01-01

    Describes a noncalculus, medical physics'' course with a basic element of direct hospital field experience. The course is intended primarily for premedical students but may be taken by nonscience majors. (Author/PR)

  13. Permeable Pavement Research - Edison, New Jersey

    Science.gov (United States)

    This presentation provides the background and summary of results collected at the permeable pavement parking lot monitored at the EPA facility in Edison, NJ. This parking lot is surfaced with permeable interlocking concrete pavers (PICP), pervious concrete, and porous asphalt. ...

  14. Pervious Pavement System Evaluation- Abstract 1

    Science.gov (United States)

    Porous pavement is a low impact development stormwater control. The Urban Watershed Management Branch is evaluating interlocking concrete pavers as a popular implementation. The pavers themselves are impermeable, but the spaces between the pavers are backfilled with washed, gra...

  15. Course-Based Undergraduate Research--It Can Be Accomplished!

    Science.gov (United States)

    Allyn, Debra A.

    2013-01-01

    This article describes a senior seminar course in the Health and Human Performance (HHP) Department at the University of Wisconsin-River Falls. All students in the HHP department are required to complete the course. The emphases within HHP include physical education, health education, and exercise and sport science. In this course students learn…

  16. Introductory Graduate Research Courses: An Examination of the Knowledge Base.

    Science.gov (United States)

    Mundfrom, Daniel J.; Shaw, Dale G.; Thomas, Ann; Young, Suzanne; Moore, Alan D.

    This study addresses the question, "What should graduate students know about research and statistics after completing an initial course?" Individuals who teach such courses at various Carnegie classifications of institutions were surveyed about the specific characteristics of an introductory graduate research course at their own institutions to…

  17. Children, urban care, and everyday pavements

    OpenAIRE

    Kim Kullman

    2014-01-01

    This paper takes a mundane piece of urban infrastructure, the pavement, as a starting point, approaching it through the experiences of 7–12-year-old children who journey between home and school in Helsinki, Finland. In doing so, the paper argues that the children and their travel companions are employing pavements to cultivate the caring potential of their city, whether this entails patting dogs, picking up empty bottles, or checking the safety of zebra crossings. Inspired by recent work on t...

  18. PAHs underfoot: contaminated dust from coal-tar sealcoated pavement is widespread in the United States.

    Science.gov (United States)

    Van Metre, Peter C; Mahler, Barbara J; Wilson, Jennifer T

    2009-01-01

    We reported in 2005 that runoff from parking lots treated with coal-tar-based sealcoat was a major source of polycyclic aromatic hydrocarbons (PAHs) to streams in Austin, Texas. Here we present new data from nine U.S. cities that show nationwide patterns in concentrations of PAHs associated with sealcoat. Dust was swept from parking lots in six cities in the central and eastern U.S., where coal-tar-based sealcoat dominates use, and three cities in the western U.S., where asphalt-based sealcoat dominates use. For six central and eastern cities, median SigmaPAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg, respectively. For three western cities, median SigmaPAH concentrations in dust from sealcoated and unsealcoated pavement are similar and very low (2.1 and 0.8 mg/kg, respectively). Lakes in the central and eastern cities where pavement was sampled have bottom sediments with higher PAH concentrations than do those in the western cities relative to degree of urbanization. Bottom-sediment PAH assemblages are similar to those of sealcoated pavement dust regionally, implicating coal-tar-based sealcoat as a PAH source to the central and eastern lakes. Concentrations of benzo[a]pyrene in dustfrom coal-tarsealcoated pavement and adjacent soils greatly exceed generic soil screening levels, suggesting that research on human-health risk is warranted. PMID:19209579

  19. PAHs underfoot: contaminated dust from coal-tar sealcoated pavement is widespread in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Peter C. Van Metre; Barbara J. Mahler; Jennifer T. Wilson [U.S. Geological Survey, Austin, TX (USA)

    2009-01-15

    We reported in 2005 that runoff from parking lots treated with coal-tar-based sealcoat was a major source of polycyclic aromatic hydrocarbons (PAHs) to streams in Austin, Texas. Here we present new data from nine U.S. cities that show nationwide patterns in concentrations of {Sigma}PAHs associated with sealcoat. Dust was swept from parking lots in six cities in the central and eastern U.S., where coal-tar-based sealcoat dominates use, and three cities in the western U.S., where asphalt-based sealcoat dominates use. For six central and eastern cities, median SPAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg, respectively. For three western cities, median SPAH concentrations in dust from sealcoated and unsealcoated pavement are similar and very low (2.1 and 0.8 mg/kg, respectively). Lakes in the central and eastern cities where pavement was sampled have bottom sediments with higher PAH concentrations than do those in the western cities relative to degree of urbanization. Bottom-sediment PAH assemblages are similar to those of sealcoated pavement dust regionally, implicating coal-tar-based sealcoat as a PAH source to the central and eastern lakes. Concentrations of benzo(a)pyrene in dust from coal-tar sealcoated pavement and adjacent soils greatly exceed generic soil screening levels, suggesting that research on human-health risk is warranted. 30 refs., 4 figs., 2 tabs.

  20. Environmental interactions of Sulphlex pavement.

    Science.gov (United States)

    Ferenbaugh, R W; Gladney, E S; Soholt, L F; Lyall, K A; Kimber Wallwork-Barber, M; Herman, L E

    1992-01-01

    Sulphlex, a mixture of elemental sulfur and plasticizers, has been considered for use as an asphalt substitute in road construction. Because this material contains substantial quantities of elemental sulfur, it is a potential substrate for growth of sulfur-oxidising bacteria. Experiments, performed to determine the susceptibility of Sulphlex in Sulphlex-containing media to degradation by Thiobacillus thiooxidans, resulted in breakdown of the Sulphlex material and concomitant production of acid. In concurrent studies, plants were grown in Sulphlex-amended soils. These plants exhibited higher sulfur content and reduced productivity as compared with plants grown in unamended soils, indicating that Sulphlex was being broken down in the soil and that the breakdown products were apparently having a detrimental effect on plant productivity. These experiments indicate that naturally occurring sulfur-oxidising bacteria have the potential to break down Sulphlex paving material, resulting in adverse effects on both the structural integrity of the pavement and the local environment. PMID:15091995

  1. 基层组合形式对沥青路面性能影响的效果评价与分析%Evaluation and Analysis on the Impact of Base Combination to Asphalt Pavement

    Institute of Scientific and Technical Information of China (English)

    李月勇

    2012-01-01

    对广昆高速公路柔性基层沥青路面试验段进行跟踪调查,包括了试验路车辙、裂缝等的调查分析.运用横向力系数车评价了路面抗滑性能.通过对检测结果的分析,以及与半刚性基层沥青路面的对比,表明基层组合方式对沥青路面使用性能影响显著,为沥青路面基层结构选型提供有益的参考.%This study based on the survey of Guangkun express way to evaluate the rut depth, crack, and SFC in-dex. The comparison between flexible base and semi-rigid base indicated that the combinations of base significantly affected the performance of asphalt pavement. This study aimes to provide a reference of flexible base design.

  2. Pavement Performance Index for Indian rural roads

    Directory of Open Access Journals (Sweden)

    Abhay Tawalare

    2016-09-01

    Full Text Available The performance of a road is evaluated from time to time so as to improve its quality and helps in planning maintenance of roads. For this purpose various pavement deteriorating models as a decision tool are available. But they are not easy to use for field engineers due to either huge past data requirement or complicated calculations. Therefore, this paper presents a Pavement Performance Index for rural roads by using simple methodology. The distress parameters of rural roads were identified through literature review. Similarly rating criteria for each distress parameters were identified through literature. For final selection of distress parameters in context of Indian rural road, opinions of five highly experienced industrial experts were taken. After that the weightage for severity of each parameter causing distress of pavement is calculated by using data of questionnaire survey in which 117 professionals working in Pradhan Mantri Gram Sadak Yojana across the country were participated. The paper suggests a formula to decide Pavement Performance Index that depends on rating criterion and severity weightage of distress parameters of pavement performance. The study concluded that suggested Pavement Performance Index makes calculations easy for field engineers and will be useful to decide priority list of rural roads for repair and maintenance schedule.

  3. A Case-Based Toxicology Elective Course to Enhance Student Learning in Pharmacotherapy

    OpenAIRE

    Brown, Stacy D.; Pond, Brooks B.; Creekmore, Kathryn A.

    2011-01-01

    Objective. To assess the impact of a case-based toxicology elective course on student learning in related required courses and student performance on the Pharmacy Curriculum Outcomes Assessment (PCOA) examination.

  4. Reliability, compliance, and security in web-based course assessments

    Directory of Open Access Journals (Sweden)

    Scott Bonham

    2008-04-01

    Full Text Available Pre- and postcourse assessment has become a very important tool for education research in physics and other areas. The web offers an attractive alternative to in-class paper administration, but concerns about web-based administration include reliability due to changes in medium, student compliance rates, and test security, both question leakage and utilization of web resources. An investigation was carried out in introductory astronomy courses comparing pre- and postcourse administration of assessments using the web and on paper. Overall no difference was seen in performance due to the medium. Compliance rates fluctuated greatly, and factors that seemed to produce higher rates are identified. Notably, email reminders increased compliance by 20%. Most of the 559 students complied with requests to not copy, print, or save questions nor use web resources; about 1% did copy some question text and around 2% frequently used other windows or applications while completing the assessment.

  5. Effects on evaporation rates from different water-permeable pavement designs.

    Science.gov (United States)

    Starke, P; Göbel, P; Coldewey, W G

    2011-01-01

    The urban water balance can be attenuated to the natural by water-permeable pavements (WPPs). Furthermore, WPPs have a 16% higher evaporation rate than impermeable pavements, which can lead to a better urban climate. Evaporation rates from pavements are influenced by the pavement surface and by the deeper layers. By a compared evaporation measurement between different WPP designs, the grain size distribution of the sub-base shows no influence on the evaporation rates in a significant way. On the contrary, a sub-base made of a twin-layer decreases the evaporation by 16% compared to a homogeneous sub-base. By a change in the colour of the paving stone, 19% higher evaporation rates could be achieved. A further comparison shows that the transpiration-effect of the grass in grass pavers increases the evaporation rates more than threefold to pervious concrete pavements. These high evapotranspiration rates can not be achieved with a pervious concrete paving stone. In spite of this, the broad field of application of the pervious concrete paving stone increases the importance in regard to the urban climate.

  6. Effects on evaporation rates from different water-permeable pavement designs.

    Science.gov (United States)

    Starke, P; Göbel, P; Coldewey, W G

    2011-01-01

    The urban water balance can be attenuated to the natural by water-permeable pavements (WPPs). Furthermore, WPPs have a 16% higher evaporation rate than impermeable pavements, which can lead to a better urban climate. Evaporation rates from pavements are influenced by the pavement surface and by the deeper layers. By a compared evaporation measurement between different WPP designs, the grain size distribution of the sub-base shows no influence on the evaporation rates in a significant way. On the contrary, a sub-base made of a twin-layer decreases the evaporation by 16% compared to a homogeneous sub-base. By a change in the colour of the paving stone, 19% higher evaporation rates could be achieved. A further comparison shows that the transpiration-effect of the grass in grass pavers increases the evaporation rates more than threefold to pervious concrete pavements. These high evapotranspiration rates can not be achieved with a pervious concrete paving stone. In spite of this, the broad field of application of the pervious concrete paving stone increases the importance in regard to the urban climate. PMID:22049757

  7. Influence of Anti-cracking Agent on Pavement Performance of Semi-rigid Base%道路抗裂缝剂在半刚性基层中的应用研究

    Institute of Scientific and Technical Information of China (English)

    谭俊民; 罗辉; 刘小波

    2011-01-01

    为减小半刚性基层材料收缩变形量,增强其抗裂能力,本课题组通过化工废料火山灰反应产物开发低成本的微膨胀道路基层抗裂缝剂,将其添加于道路基层混合料中.通过对半刚性基层材料掺加抗裂缝剂的试验研究,分析了抗裂缝剂对半刚性基层材料的水泥净浆凝结时间、基本力学性能和材料收缩性能的影响;并借助SEM测试手段,从微观上对水泥体系中钙矾石的生成进行了分析.结果表明,半刚性基层抗裂缝剂具有很好的微膨胀性和增密性,使道路基层结构因温度和湿度的变化引起材料收缩的空间大大减少,源头上解决路面裂缝难题,延长道路使用寿命.%In order to reduce shrinkage deformation and enhance the crack resistance of the semi-rigid base materials, a low-cost and micro-expansion anti-cracking agent is developed from pozzolanic reaction waste to reduce the cracks in the road or pavement. The influence of anti-cracking agent on setting time of cement paste, basic mechanical property and shrinkage property is analyzed, and by the scanning electronic microscope (SEM) testing approach, the generation of ettringite from cement system is investigated from the perspective of microscopic. The test results indicate that the semi-rigid base added anti-cracking agent has a good micro-expansion and densification, which makes the shrinkage space caused by the temperature and humidity change significantly reduced, improves the pavement performance of semi-rigid base and prolongs the roadway service life.

  8. Improving a pavement-watering method on the basis of pavement surface temperature measurements

    CERN Document Server

    Hendel, Martin; Diab, Youssef; Royon, Laurent

    2014-01-01

    Pavement-watering has been studied since the 1990's and is currently considered a promising tool for urban heat island reduction and climate change adaptation. However, possible future water resource availability problems require that water consumption be optimized. Although pavement heat flux can be studied to improve pavement-watering methods (frequency and water consumption), these measurements are costly and require invasive construction work to install appropriate sensors in a dense urban environment. Therefore, we analyzed measurements of pavement surface temperatures in search of alternative information relevant to this goal. It was found that high frequency surface temperature measurements (more than every 5 minutes) made by an infrared camera can provide enough information to optimize the watering frequency. Furthermore, if the water retaining capacity of the studied pavement is known, optimization of total water consumption is possible on the sole basis of surface temperature measurements.

  9. Oxygen demand of aircraft and airfield pavement deicers and alternative freezing point depressants

    Science.gov (United States)

    Corsi, Steven R.; Mericas, Dean; Bowman, George

    2012-01-01

    Aircraft and pavement deicing formulations and other potential freezing point depressants were tested for biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Propylene glycol-based aircraft deicers exhibited greater BOD5 than ethylene glycol-based aircraft deicers, and ethylene glycol-based products had lower degradation rates than propylene glycol-based products. Sodium formate pavement deicers had lower COD than acetate-based pavement deicers. The BOD and COD results for acetate-based pavement deicers (PDMs) were consistently lower than those for aircraft deicers, but degradation rates were greater in the acetate-based PDM than in aircraft deicers. In a 40-day testing of aircraft and pavement deicers, BOD results at 20°C (standard) were consistently greater than the results from 5°C (low) tests. The degree of difference between standard and low temperature BOD results varied among tested products. Freshwater BOD test results were not substantially different from marine water tests at 20°C, but glycols degraded slower in marine water than in fresh water for low temperature tests. Acetate-based products had greater percentage degradation than glycols at both temperatures. An additive component of the sodium formate pavement deicer exhibited toxicity to the microorganisms, so BOD testing did not work properly for this formulation. BOD testing of alternative freezing point depressants worked well for some, there was little response for some, and for others there was a lag in response while microorganisms acclimated to the freezing point depressant as a food source. Where the traditional BOD5 test performed adequately, values ranged from 251 to 1,580 g/kg. Where the modified test performed adequately, values of BOD28 ranged from 242 to 1,540 g/kg.

  10. 基于非线性疲劳损伤的沥青路面轴载换算%AXLE LOAD CONVERSION OF ASPHALT PAVEMENT BASED ON NONLINEAR FATIGUE DAMAGE

    Institute of Scientific and Technical Information of China (English)

    吕松涛

    2012-01-01

    In order to establish the non-linear fatigue damage evolution equation of asphalt mixture and the axial load conversion method of asphalt pavement,the aggregate gradation and optimum asphalt-aggregate ratios are determined by a proportion design of asphalt mixture.Then,the fatigue damage variable is defined by the modulus decay basing on the basic theory of damage mechanics.The fatigue damage equation was deduced.The direct tensile fatigue test results were fitted from using the fatigue damage equation.The regularities of model parameters and damage with a stress ratio are given out.The new axle load conversion method is established for asphalt pavement.The results indicate that the fatigue damage evolution has the apparent non-linear properties of asphalt mixture.The Miner linear fatigue damage theory is not suitable to describe the process of fatigue damage evolution for asphalt pavement.It is not safe to use the axial load conversion method deriving from the Miner equation.The new axial load conversion method basing on the nonlinear fatigue damage evolution can consider the influence of loading history and damage history.%为了建立沥青混合料的非线性疲劳损伤演化方程,同时为完善沥青路面的轴载换算方法,首先进行沥青混合料的配合比设计,确定矿料级配及最佳油石比,然后从损伤力学基本理论出发,定义模量衰减为其疲劳损伤参量,由此推导得到了疲劳损伤方程,并以此方程对小梁直接拉伸疲劳试验结果进行拟合,得到了模型参数和损伤随应力比的变化规律,建立了沥青路面轴载换算新方法。结果表明:沥青混合料的疲劳损伤演化具有明显的非线性,用Miner线性疲劳损伤理论来描述沥青路面疲劳损伤演化过程不合适,由此推导得到的轴载换算方法偏不安全,建立在非线性疲劳损伤演化基础上的轴载换算方法考虑了加载历史和损伤历史的影响。

  11. State-of-the-art review of the applications of nanotechnology in pavement materials

    Science.gov (United States)

    Castillo, Luis, Jr.

    The use of nanotechnology in pavement materials is one main area that shows great promise and has the potential to change commonly used materials. This will develop more effective solutions to achieve the desired performance. The overall objective of this work is to present a state-of-the-art literature review of nano-science-based principles to improve the performance and, ultimately, the life cycle of transportation construction materials. This work will be organized into two different parts. The first part will consist of six sections: applications of nanotechnology in concrete pavements, applications of nanotechnology in asphalt pavement, application of nanotechnology in general soils, cost-benefit analysis, challenges, and trends to the future. In addition, a current practice review was performed from a literature review that included a questionnaire of the knowledge and opinion about nanotechnology, which included students, general contractors, teachers, engineers, and architects. The second part will deal with the advancement of the application of nanotechnology in pavement materials for different developed countries. Because nanotechnology is relatively a young field in pavement materials, limited research has been conducted in North America, Europe, and Asia. A comparison of the advancement of nano-science-based principles, as applied to the performance and life cycle of transportation materials, for the three continents will be carried out in a summarized manner.

  12. Impact of Vehicle Class and Tire Pressure on Pavement Performance in MEPDG

    Directory of Open Access Journals (Sweden)

    Mohamed I. E. Attia

    2014-10-01

    Full Text Available The new Mechanistic-Empirical Pavement Design Guide (MEPDG design and analysis procedures defines the exact traffic loading by defining the specific number of each vehicle class and the use of axle load distribution factors instead of the equivalent single axle load (ESAL. The number of traffic inputs (parameters in MEPDG was found to be 17024. This research aimed to evaluate the sensitivity of the predicted flexible pavement distress to vehicle class and tire pressure in MEPDG. To evaluate the impact of vehicle (truck class on pavement sections, different cases of loading were analyzed. For each case, the MEPDG Ver. 1.1 was used to evaluate the effect of tire pressure by solving each case for a tire pressure of 120 and 140 psi. The effect of the traffic parameters on asphalt pavement (AC rutting, base rutting, subgrade rutting, international roughness index (IRI, longitudinal cracking and fatigue (alligator cracking were investigated. It was found that vehicle class distribution (VCD would cause clear impact (comparable to the effect of AADTT level only if the major traffic is of specific class (very light or very heavy. If this is not the case, the vehicle class distribution will not be a significant factor that affects the final design because most of the trucks had similar impact on flexible pavement distresses. The impact of tire pressure is clear on longitudinal cracking, fatigue cracking and AC rutting, and have no significant impact on both base and subgrade rutting.

  13. The Greenhouse Gas Emission from Portland Cement Concrete Pavement Construction in China.

    Science.gov (United States)

    Ma, Feng; Sha, Aimin; Yang, Panpan; Huang, Yue

    2016-01-01

    This study proposes an inventory analysis method to evaluate the greenhouse gas (GHG) emissions from Portland cement concrete pavement construction, based on a case project in the west of China. The concrete pavement construction process was divided into three phases, namely raw material production, concrete manufacture and pavement onsite construction. The GHG emissions of the three phases are analyzed by a life cycle inventory method. The CO₂e is used to indicate the GHG emissions. The results show that for 1 km Portland cement concrete pavement construction, the total CO₂e is 8215.31 tons. Based on the evaluation results, the CO₂e of the raw material production phase is 7617.27 tons, accounting for 92.7% of the total GHG emissions; the CO₂e of the concrete manufacture phase is 598,033.10 kg, accounting for 7.2% of the total GHG emissions. Lastly, the CO₂e of the pavement onsite construction phase is 8396.59 kg, accounting for only 0.1% of the total GHG emissions. The main greenhouse gas is CO₂ in each phase, which accounts for more than 98% of total emissions. N₂O and CH₄ emissions are relatively insignificant. PMID:27347987

  14. The Greenhouse Gas Emission from Portland Cement Concrete Pavement Construction in China

    Science.gov (United States)

    Ma, Feng; Sha, Aimin; Yang, Panpan; Huang, Yue

    2016-01-01

    This study proposes an inventory analysis method to evaluate the greenhouse gas (GHG) emissions from Portland cement concrete pavement construction, based on a case project in the west of China. The concrete pavement construction process was divided into three phases, namely raw material production, concrete manufacture and pavement onsite construction. The GHG emissions of the three phases are analyzed by a life cycle inventory method. The CO2e is used to indicate the GHG emissions. The results show that for 1 km Portland cement concrete pavement construction, the total CO2e is 8215.31 tons. Based on the evaluation results, the CO2e of the raw material production phase is 7617.27 tons, accounting for 92.7% of the total GHG emissions; the CO2e of the concrete manufacture phase is 598,033.10 kg, accounting for 7.2% of the total GHG emissions. Lastly, the CO2e of the pavement onsite construction phase is 8396.59 kg, accounting for only 0.1% of the total GHG emissions. The main greenhouse gas is CO2 in each phase, which accounts for more than 98% of total emissions. N2O and CH4 emissions are relatively insignificant. PMID:27347987

  15. The Greenhouse Gas Emission from Portland Cement Concrete Pavement Construction in China.

    Science.gov (United States)

    Ma, Feng; Sha, Aimin; Yang, Panpan; Huang, Yue

    2016-06-24

    This study proposes an inventory analysis method to evaluate the greenhouse gas (GHG) emissions from Portland cement concrete pavement construction, based on a case project in the west of China. The concrete pavement construction process was divided into three phases, namely raw material production, concrete manufacture and pavement onsite construction. The GHG emissions of the three phases are analyzed by a life cycle inventory method. The CO₂e is used to indicate the GHG emissions. The results show that for 1 km Portland cement concrete pavement construction, the total CO₂e is 8215.31 tons. Based on the evaluation results, the CO₂e of the raw material production phase is 7617.27 tons, accounting for 92.7% of the total GHG emissions; the CO₂e of the concrete manufacture phase is 598,033.10 kg, accounting for 7.2% of the total GHG emissions. Lastly, the CO₂e of the pavement onsite construction phase is 8396.59 kg, accounting for only 0.1% of the total GHG emissions. The main greenhouse gas is CO₂ in each phase, which accounts for more than 98% of total emissions. N₂O and CH₄ emissions are relatively insignificant.

  16. A Preliminary Study on Web-based English Course Design and Materials Development

    OpenAIRE

    Shuhama, Yuji; シュハマ, ユウジ; 主濱, 祐二

    2010-01-01

    Abstract:In this article, we consider what an effective web-based English course and its course materials should be in order to promote English learning of advanced course students at technical colleges. We review second language acquisition theories and researches and some case studies at other technical colleges. We will apply the research findings to our web-based English course and create an effective and learner-centered e-learning course. Keywords: web-based, e-learning, second languag...

  17. Detecting Concepts Crucial for Success in Mathematics Courses from Knowledge State-based Placement Data

    CERN Document Server

    Harper, Marc

    2013-01-01

    We show that individual topics and skills can have a dramatic effect on the outcomes of students in various mathematics courses at the University of Illinois. Data from the placement program at Illinois associates a knowledge state, a subset of 182 items and skills that a student is able to complete successfully and repeatedly, with their final grades in a variety of courses from college algebra through multivariate calculus. Using various conditional probabilities and odds ratios, we classify items based on their association with successful and unsuccessful course outcomes, showing that some skills that are advanced for some courses are fundamental or basic to more advanced courses. We examine the impact of specific items across the courses in the traditional college algebra, precalculus, and calculus sequence, as well as courses not typically covered by placement programs, such as higher calculus courses. Visualizations of the knowledge states associated to each student are given for some specific courses a...

  18. Inquiry-based course in physics and chemistry for preservice K-8 teachers

    Directory of Open Access Journals (Sweden)

    Michael E. Loverude

    2011-05-01

    Full Text Available We describe an inquiry-based course in physics and chemistry for preservice K-8 teachers developed at California State University Fullerton. The course is one of three developed primarily to enhance the science content understanding of prospective teachers. The course incorporates a number of innovative instructional strategies and is somewhat unusual for its interdisciplinary focus. We describe the course structure in detail, providing examples of course materials and assessment strategies. Finally, we provide research data illustrating both the need for the course and the effectiveness of the course in developing student understanding of selected topics. Student responses to various questions reflect a lack of understanding of many relatively simple physical science concepts, and a level of performance that is usually lower than that in comparable courses serving a general education audience. Additional data suggest that course activities improve student understanding of selected topics, often dramatically.

  19. Study on Design Index and Model for Controlling Permanent Deformation of Granular Base Course%粒料基层设计指标和控制模型研究

    Institute of Scientific and Technical Information of China (English)

    高启聚; 姚祖康

    2016-01-01

    为提出控制粒料基层永久变形的设计指标并建立控制模型,采用两种级配碎石,3种围压和不同应力比为试验加载条件,利用重复荷载三轴试验和安定理论,研究了粒料的永久变形安定特性.为了克服试验加载次数的限制,对试验结果进行了统计回归和曲线拟合.根据拟合结果,利用试验曲线外延的方法,分析了粒料永久变形处于不同安定状态下的安定极限荷载,提出了在A区(塑性安定状态)内建立控制粒料基层永久变形设计模型的原则.利用分层应变总和法和美国力学经验法路面设计指南目前所采用的粒料层永久变形预估模型,计算了典型沥青路面结构的粒料基层永久变形,确定了粒料基层永久变形量和永久应变临界值标准,在此基础上提出了控制粒料基层永久变形的应力比设计指标,初步建立了基于室内试验的应力比与荷载作用次数回归公式的控制模型.%To introduce a design index and a model for controlling permanent deformation of granular base course for asphalt pavements, by adopting 2 types of graded macadam, 3 kinds of confining pressure stresses and different stress ratios as test loading conditions, the permanent deformation shakedown characteristics of the graded macadam are examined using triaxial repeated load test based on shakedown theory. The methods of statistical regression and curve fitting are used to the testing result in order to overcome the limitation of the number of repeated loads. According to the fitting result, the method of extension of testing curves is used to analyze the limit stresses for shakedown under different shakedown statuses of permanent deformation of the aggregates, and the principle of establishing design model for controlling permanent deformation of granular base course in zone A ( plastic shakedown status) is put forward. The permanent deformation of granular base courses of typical asphalt pavement

  20. 基于环境温度变化的混合式基层沥青路面结构疲劳损伤分析%Fatigue damage analysis of composite base asphalt pavement structure based on change of ambient temperature

    Institute of Scientific and Technical Information of China (English)

    郭芳; 付宏渊; 邵腊庚

    2015-01-01

    In order to analyze the fatigue characteristics of composite base asphalt pavement structure under the change of ambient temperature, the impact of Hechi temperatures of each month in Guangxi and seasonal variations of subgrade resilient modulus were considered, and three kinds of asphalt pavement structures on composite base were put forward. With ABAQUS software, two states between layers were considered, and the temperature field, strain response and the cumulative fatigue damage of four pavement structures were calculated and analyzed. By monitoring results oftemperature sensors and strain gauges with straight road tests, simulation models were used to calculate fatigue damage of asphalt layer. The results indicate that the strain response with different temperature fields in each month in asphalt pavement is varied. When the temperature increases, the tensile strain at the bottom of asphalt layer increases. The fatigue damage in different seasons is varied and has high proportion in high temperature season. Based on the ambient temperature change considerations, the temperature sensitivity of scheme B is the smallest (scheme B means composite base asphalt pavement which is made of cement stabilized, graded gravel for the base layer and large size asphalt macadam mixture layer), and its fatigue damage is the minimum. The research results can provide reference for choosing good pavement structure on composite base.%为了分析环境温度变化时混合式基层沥青路面结构的疲劳损伤特性,拟定3种混合式基层沥青路面结构,充分考虑广西河池地区各月温度变化以及土基回弹模量的季节性变化,运用ABAQUS软件对2种层间结合状态的4种路面结构方案的温度场、应变响应和疲劳损伤进行计算分析,通过试验路面温度传感器、应变片的监测结果和疲劳损伤模拟模型计算沥青层的疲劳损伤。研究结果表明:在不同月份温度下,沥青路面应变响应差

  1. 基于BISAR软件的半柔性复合路面层间粘结力分析%The Analysis of Layer Cohesive Force of Semi-flexible Composite Pavement Based on the Software of BISAR

    Institute of Scientific and Technical Information of China (English)

    高建华; 王兆仑

    2013-01-01

    As research the influence of pavement structure stress of layer cohesive force of Semiflexible composite pavement.This paper uses the BISAR software for calculating the typical structure layer of the design pavement form the protocol road traffic and material parameters.Designing Semi-flexible composite pavement as the top layer of typical structure and the asphalt pavement structure layer.Influence the interlayer bonding Semi-flexible composite pavementt deflection,shear stress,driving direction tensile stress and load direction tensile stress.The results showed that the interlayer bonding status for composite pavement structure layer of the deflection and stress distribution has special significant influence.So it is suggested that in the design of the pavement of interlayer bonding for key consideration.%为研究半柔性复合路面层间粘结力对路面结构层应力的影响.通过拟定路面交通量以及材料参数,通过BISAR软件进行设计路面典型结构层计算,设计出以半柔性复合材料作为上面层的典型结构层以及沥青路面结构层,并研究层间粘结对半柔性复合路面弯沉、剪应力、行车方向拉应力和荷载方向拉应力的影响.结果表明层间粘结对半柔性复合路面弯沉、剪应力分布具有一定影响,建议在设计时将层间粘结作为重点考虑指标之一.

  2. Design of Subgrade Resilient Modulus Based on Coordinate Deformation of Subgrade and Pavement%基于路基路面协调变形的路基回弹模量设计

    Institute of Scientific and Technical Information of China (English)

    董城; 岳志平; 李志勇; 冷伍明

    2012-01-01

    基于路基路面协调变形,建立三维有限元分析模型.采用该模型对典型水泥混凝土路面结构的荷载应力进行计算,分析了轴重、轴型对路基工作区应力和变形的影响.结果表明,随着轴重和与轴数的增加,路基工作区深度不断扩展,同时该范围内的应力和变形也不断增大;多轴荷载在路基中产生的响应均高于单轴荷载,同时多轴荷载应力的叠加效应在路基深层愈加显著.在重载作用下,现行规范将0~80 cm作为路基工作区深度是不够的,随着重载和超载的加剧,可将交通荷载影响区加深至1.5m.基于不同路基回弹模量下路基路面应力应变响应,提出了路基回弹模量的合理设计值,并结合水泥处治土的回弹模量试验,提出了最佳水泥处治剂量,为基于路基路面协调变形的路基回弹模量设计提供了思路.%Based on the principle of coordinate deformation of subgrade and pavement, the 3D finite element model was established and used for load stress analysis of typical cement concrete pavement structure, the stress and deformation of the subgrade workspace were calculated under all kinds of axle load and configuration. The analysis results indicate that ( 1 ) The depth of subgrade workspace, the stress and deformation level in this region increased with increasing the axle load and the number of axles. (2) The stress induced by multi-axle load exceeded that of the single one, the overlapped stress induced by multi-axle load in the deep-seated subgrade was remarkable. (3 ) Under heavy traffic, the subgrade workspace of 0 -80 cm depth specified in current specification is not enough. According to the analysis, the subgrade workspace depth of expressway can be 1.5 m. The reasonable subgrade resilient modulus was put forward in accordance with the responses of stress and strain in pavement and subgrade with different subgrade resilient moduli. The optimal cement content was proposed in

  3. 磷渣微粉基隧道沥青路面阻燃剂的制备及其性能试验%Preparation and performance test phosphorus slag powder base tunnel asphalt pavement retardants

    Institute of Scientific and Technical Information of China (English)

    钱国平; 王坤; 郑卫芳

    2016-01-01

    针对隧道沥青路面防火安全问题,配制了6种磷渣微粉基材阻燃剂 A~F。通过 DSC 试验评价了各阻燃剂阻燃性能,选出了最优阻燃剂;对掺入不同掺量的阻燃改性沥青进行路用性能试验和极限氧指数试验,分析了阻燃剂最佳掺量和阻燃效果;采用锥形热试验对阻燃沥青混合料进行阻燃性能研究。试验结果表明,阻燃剂 D,F 有明显的两个吸热峰;阻燃剂 D 和 F 的加入使沥青的氧指数得到显著的提高;不同掺量阻燃剂 D,F 的加入,能够满足沥青路用性能的要求,阻燃剂的最佳掺量为8%;与非阻燃改性沥青混合料相比,阻燃改性沥青的引燃时间变长,热释放速率减缓,总释热量全过程低于非阻燃沥青混合料。阻燃剂 D,F 的加入对沥青及沥青混合料的阻燃效果明显,且阻燃剂 D 阻燃效果最优。%Six kinds of phosphorus slag powder-based flame retardants were prepared in or-der to solve fire-proof safety problem of tunnel asphalt pavement A-F.The combustion prop-erties of flame retardants were evaluated by DSC experiment and the optimal flame retard-ants were selected.The pavement performance and limiting oxygen index of flame-retardant modified asphalt with different amounts of retardants were tested,then the optimum a-mount of flame retardants and flame retardancy were analyzed.The Cone thermal test was conducted to study the flame retardant properties of flame retardant asphalt mixture.the re-sults show that flame D,F two endothermic peaks are obvious.With the addition of flame retardant D and F,the oxygen index of asphalt was significantly improved.Different dosage of the addition of flame retardant D,F can meet the requirements of the pavement perform-ance.The optimum amount of flame retardant is 8%.Compared with the nonflame-retardant asphalt mixture,the retardancy of flame-retardant modified asphalt mixture is better:its ig-nition time is longer,heat release rate is slower and the

  4. Quantitative Assessment of a Field-Based Course on Integrative Geology, Ecology and Cultural History

    Science.gov (United States)

    Sheppard, Paul R.; Donaldson, Brad A.; Huckleberry, Gary

    2010-01-01

    A field-based course at the University of Arizona called Sense of Place (SOP) covers the geology, ecology and cultural history of the Tucson area. SOP was quantitatively assessed for pedagogical effectiveness. Students of the Spring 2008 course were given pre- and post-course word association surveys in order to assess awareness and comprehension…

  5. Inquiry-Based Course in Physics and Chemistry for Preservice K-8 Teachers

    Science.gov (United States)

    Loverude, Michael E.; Gonzalez, Barbara L.; Nanes, Roger

    2011-01-01

    We describe an inquiry-based course in physics and chemistry for preservice K-8 teachers developed at California State University Fullerton. The course is one of three developed primarily to enhance the science content understanding of prospective teachers. The course incorporates a number of innovative instructional strategies and is somewhat…

  6. Making Students Do the Thinking: Team-Based Learning in a Laboratory Course

    Science.gov (United States)

    Simonson, Shawn R.

    2014-01-01

    Team-based learning (TBL) is a teaching pedagogy for flipping the classroom that moves the focus of the classroom from the instructor conveying course concepts via lecture to the application of concepts by student teams. It has been used extensively in lecture courses; however, there is little evidence of its use in laboratory courses. The purpose…

  7. Designing “Theory of Machines and Mechanisms” course on Project Based Learning approach

    DEFF Research Database (Denmark)

    Shinde, Vikas

    2013-01-01

    by the industry and the learning outcomes specified by the National Board of Accreditation (NBA), India; this course is restructured on Project Based Learning approach. A mini project is designed to suit course objectives. An objective of this paper is to discuss the rationale of this course design...... and the process followed to design a project which meets diverse objectives....

  8. Assessment of Problem-Based Learning in the Undergraduate Statistics Course

    Science.gov (United States)

    Karpiak, Christie P.

    2011-01-01

    Undergraduate psychology majors (N = 51) at a mid-sized private university took a statistics examination on the first day of the research methods course, a course for which a grade of "C" or higher in statistics is a prerequisite. Students who had taken a problem-based learning (PBL) section of the statistics course (n = 15) were compared to those…

  9. Implementation and Validation of the Viscoelastic Continuum Damage Theory for Asphalt Mixture and Pavement Analysis in Brazil

    Science.gov (United States)

    Nascimento, Luis Alberto Herrmann do

    This dissertation presents the implementation and validation of the viscoelastic continuum damage (VECD) model for asphalt mixture and pavement analysis in Brazil. It proposes a simulated damage-to-fatigue cracked area transfer function for the layered viscoelastic continuum damage (LVECD) program framework and defines the model framework's fatigue cracking prediction error for asphalt pavement reliability-based design solutions in Brazil. The research is divided into three main steps: (i) implementation of the simplified viscoelastic continuum damage (S-VECD) model in Brazil (Petrobras) for asphalt mixture characterization, (ii) validation of the LVECD model approach for pavement analysis based on field performance observations, and defining a local simulated damage-to-cracked area transfer function for the Fundao Project's pavement test sections in Rio de Janeiro, RJ, and (iii) validation of the Fundao project local transfer function to be used throughout Brazil for asphalt pavement fatigue cracking predictions, based on field performance observations of the National MEPDG Project's pavement test sections, thereby validating the proposed framework's prediction capability. For the first step, the S-VECD test protocol, which uses controlled-on-specimen strain mode-of-loading, was successfully implemented at the Petrobras and used to characterize Brazilian asphalt mixtures that are composed of a wide range of asphalt binders. This research verified that the S-VECD model coupled with the GR failure criterion is accurate for fatigue life predictions of Brazilian asphalt mixtures, even when very different asphalt binders are used. Also, the applicability of the load amplitude sweep (LAS) test for the fatigue characterization of the asphalt binders was checked, and the effects of different asphalt binders on the fatigue damage properties of the asphalt mixtures was investigated. The LAS test results, modeled according to VECD theory, presented a strong correlation with

  10. Teaching Compressed-Format Courses: Teacher-Based Best Practices

    Science.gov (United States)

    Kops, William J.

    2014-01-01

    This study provides insight into how highly rated instructors approached teaching compressed summer session courses, and offers a set of best practices that others might use when teaching in similar settings. Top-rated instructors indicated differences in the way they taught compressed-format summer session courses, with respect to course…

  11. Evaluating an Inquiry-Based Bioinformatics Course Using Q Methodology

    Science.gov (United States)

    Ramlo, Susan E.; McConnell, David; Duan, Zhong-Hui; Moore, Francisco B.

    2008-01-01

    Faculty at a Midwestern metropolitan public university recently developed a course on bioinformatics that emphasized collaboration and inquiry. Bioinformatics, essentially the application of computational tools to biological data, is inherently interdisciplinary. Thus part of the challenge of creating this course was serving the needs and…

  12. Differentiating Biochemistry Course Laboratories Based on Student Experience

    Science.gov (United States)

    Jakubowski, Henry V.

    2011-01-01

    Content and emphases in undergraduate biochemistry courses can be readily tailored to accommodate the standards of the department in which they are housed, as well as the backgrounds of the students in the courses. A more challenging issue is how to construct laboratory experiences for a class with both chemistry majors, who usually have little or…

  13. Course Management and Students' Expectations: Theory-Based Considerations

    Science.gov (United States)

    Buckley, M. Ronald; Novicevic, Milorad M.; Halbesleben, Jonathon R. B.; Harvey, Michael

    2004-01-01

    This paper proposes a theoretical, yet practical, framework for managing the formation process of students unrealistic expectations in a college course. Using relational contracting theory, alternative teacher interventions, aimed at effective management of students expectations about the course, are described. Also, the formation of the student…

  14. Application of viscoelastic continuum damage approach to predict fatigue performance of Binzhou perpetual pavements

    Directory of Open Access Journals (Sweden)

    Wei Cao

    2016-04-01

    Full Text Available For this study, the Binzhou perpetual pavement test sections constructed in Shandong Province, China, were simulated for long-term fatigue performance using the layered viscoelastic pavement analysis for critical distresses (LVECD finite element software package. In this framework, asphalt concrete was treated in the context of linear viscoelastic continuum damage theory. A recently developed unified fatigue failure criterion that defined the boundaries of the applicable region of the theory was also incorporated. The mechanistic modeling of the fatigue mechanisms was able to accommodate the complex temperature variations and loading conditions of the field pavements in a rigorous manner. All of the material models were conveniently characterized by dynamic modulus tests and direct tension cyclic fatigue tests in the laboratory using cylindrical specimens. By comparing the obtained damage characteristic curves and failure criteria, it is found that mixtures with small aggregate particle sizes, a dense gradation, and modified asphalt binder tended to exhibit the best fatigue resistance at the material level. The 15-year finite element structural simulation results for all the test sections indicate that fatigue performance has a strong dependence on the thickness of the asphalt pavements. Based on the predicted location and severity of the fatigue damage, it is recommended that Sections 1 and 3 of the Binzhou test sections be employed for perpetual pavement design.

  15. Knowledge Discovery and Pavement Performance: Intelligent Data Mining

    NARCIS (Netherlands)

    Miradi, M.

    2009-01-01

    The main goal of the study was to discover knowledge from data about asphalt road pavement problems to achieve a better understanding of the behavior of them and via this understanding improve pavement quality and enhance its lifespan. Four pavement problems were chosen to be investigated; raveling

  16. Effect of age of permeable pavements on their infiltration function

    NARCIS (Netherlands)

    Boogaard, Floris; Lucke, Terry; Beecham, Simon

    2013-01-01

    This study describes field investigations designed to compare the infiltration capacities of 55 permeable pavement systems installed in the Netherlands and in Australia. The ages of the pavements varied from 1 to 12 years. Using infiltrometer testing, the performance of the pavements has been compar

  17. A TECHNIQUE OF ESTIMATION OF TECHNICAL CONDITION OF RIGID AIRFIELD PAVEMENTS IN THE CONTEXT OF RISK THEORY

    Directory of Open Access Journals (Sweden)

    A. N. Popov

    2012-02-01

    Full Text Available Problem statement. To provide for safe takeoff and landing of modern aviation complexes, specialattention is given to technical condition of artificial pavements of runways which can be serviceableor faulty, efficient or limiting. Available standard methods of an expeditious estimation of an operational-technical condition of airfield pavements are based on general principles of defect graduationand of definition of integrated total generalized indicator of pavement condition and often yield theresults contradicting each other, which complicate making decision in relation to operation.Results and conclusions. The classification of linear constructions of airfields by responsibilitylevel is proposed. Theoretical basics and practical recommendations on estimation of a technicalcondition of rigid airfield pavements by permissible level of are formulated with respect to level ofrisk with the use of principals of reliability theory and of risk theory. The recommendations proposedrest on new principles of technical regulation established by Federal Law N 184-FZ “Ontechnical regulation”.

  18. The Effect of Slope Geometry and Shoulder on Rutting Depth of Flexible Pavement

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Khabiri

    2015-05-01

    Full Text Available The slope and width of the road shoulder are important parameters in geometry of the road pavement. Therefore, it is important to comply with the requirements relating to the slope and width of the shoulders. So that by using the minimum width and slope of the shoulders according to regulations not only stresses and strains transferred to the lower layers will decrease, but also reduces damages in asphalt layers, base, and sub-base. Therefore, it is vital to conduct analyses which can bring good amount of accuracy in assessment of the stress and settlement due to shoulder width and slope. The aim of this study is to investigate the effect of geometry of the shoulder on the performance and behavior of weak or strong pavement. For this purpose, numerical two-dimensional modeling of the road pavement (asphalt،base،sub-base on which the axel load is placed was done using finite element method, ABAQUS, and the effect of the shoulder width and slope on the stresses and settlements caused by the strong and weak pavement have been studied. Also for verification of the software, several obtained field values are compared to each other. The results indicate that the increase in the width of the shoulders and the decrease in the slope will cause in decrease of the stress and settlements in different layers of the roadways. Thus, creating less steeper shoulder and wider pavement can reduce damages and will contribute to the increased safety and sustained life of the pavement.

  19. The Case of Web-Based Course on Taxation: Current Status, Problems and Future Improvement

    Science.gov (United States)

    Qin, Zhigang

    This paper mainly introduces the case of the web-based course on taxation developed by Xiamen University. We analyze the current status, problems and future improvement of the web-based course. The web-based course has the basic contents and modules, but it has several problems including unclear object, lacking interaction, lacking examination module, lacking study management module, and the learning materials and the navigation are too simple. According to its problems, we put forward the measures to improve it.

  20. 丹通高速公路沥青路面新材料、新工艺的应用%Application of New Material and New Technology of Asphalt Pavement of Dantong Expressway

    Institute of Scientific and Technical Information of China (English)

    刘立安

    2012-01-01

    Several new ideas adopted in Dantong Expressway pavement design are introduced, including rubber asphalt, flame retardant asphalt, warm mix asphalt, large grain size asphalt macadam and cement stabilized macadam base course in the type of closed skeleton compaction.%介绍了丹通高速路面设计采用的一些新的材料和新的工艺,包括橡胶沥青、阻燃沥青、温拌沥青、大粒径沥青碎石以及紧密嵌挤骨架密实型水泥稳定碎石基层。

  1. Modelling of composite concrete block pavement systems applying a cohesive zone model

    DEFF Research Database (Denmark)

    Skar, Asmus; Poulsen, Peter Noe

    This paper presents a numerical analysis of the fracture behaviour of the cement bound base material in composite concrete block pavement systems, using a cohesive zone model. The functionality of the proposed model is tested on experimental and numerical investigations of beam bending tests...... that the cohesive model is suitable for simulation of crack propagation in cement bound materials subjected to monotonic loading. The methodology implemented gives a new understanding of the mechanical behaviour of cement bound materials which can be used in further refinements of mechanical models for composite...... block pavements. It is envisaged that the methodology implemented in this study can be extended and thereby contribute to the ongoing development of rational failure criteria that can replace the empirical formulas currently used in pavement engineering....

  2. Design of airport pavements for expansive soils

    Science.gov (United States)

    McKeen, R. G.

    1981-01-01

    Expansive soil subgrades exhibit volume changes with variation in moisture condition. These changes result in differential movement of airport pavements resting on these soils. Special design procedures must be used to account for the expansive soil activity during equilibration. In addition, special precautions are required to protect the subgrade from moisture variation with climate. Measurement of soil suction is a key step in quantifying moisture-induced soil behavior. Procedures are outlined for suction characterization of the soil and for estimating the in situ differential movement likely to occur under the pavement. Once the wavelength and amplitude characteristics of the differential movement are obtained, design calculations to select the thickness and materials for the pavement may proceed.

  3. Creating a Standards-Based Economics Principles Course

    OpenAIRE

    W. Lee Hansen; Michael K. Salemi; John J. Siegfried

    2001-01-01

    America's adult population is economically illiterate. College economics instruction must shoulder some of the blame for this situation. Forty percent of all college graduates take an economics course. Over 95 percent of principles of economics students do not continue on to major in economics, however. For them, introductory economics is a terminal course. To improve adult economic literacy the authors argue for replacing much of the detail and technical material in the traditional two-semes...

  4. Effects of cross-anisotropy and stress-dependency of pavement layers on pavement responses under dynamic truck loading

    Directory of Open Access Journals (Sweden)

    Rafiqul A. Tarefder

    2016-06-01

    Full Text Available Previous studies by the authors have determined pavement responses under dynamic loading considering cross-anisotropy in one layer only, either the cross-anisotropic viscoelastic asphalt concrete (AC layer or the cross-anisotropic stress-dependent base layer, but not both. This study evaluates pavement stress–strain responses considering cross-anisotropy in all layers, i.e. AC, base and subbase, using finite element modeling (FEM technique. An instrumented pavement section on Interstate I-40 near Albuquerque, New Mexico was used in ABAQUS framework as model geometry. Field asphalt cores were collected and tested in the laboratory to determine the cross-anisotropy (n-values defined by horizontal to vertical modulus ratio, and other viscoelastic parameters as inputs of the model incorporated through user defined material interface (UMAT functionality in ABAQUS. Field base and subbase materials were also collected and tested in the laboratory to determine stress-dependent nonlinear elastic model parameters, as inputs of the model, again incorporated through UMAT. The model validation task was carried out using field-measured deflections and strain values under falling weight deflectometer (FWD loads at the instrumented section. The validated model was then subjected to an actual truck loading for studying cross-anisotropic effects. It was observed that horizontal tensile strain at the bottom of the AC layer and vertical strains in all layers decreased with an increase in n-value of the asphalt layer, from n < 1 (anisotropy to n=1 (isotropy. This indicates that the increase in horizontal modulus caused the decrease in layer strains. It was also observed that if the base and subbase layers were considered stress-dependent instead of linear elastic unbound layers, the horizontal tensile strain at the bottom of the asphalt layer increased and vertical strains on top of the base and subbase also increased.

  5. Effects of cross-anisotropy and stress-dependency of pavement layers on pavement responses under dynamic truck loading

    Institute of Scientific and Technical Information of China (English)

    Rafiqul A. Tarefder; Mesbah U. Ahmed; Asifur Rahman

    2016-01-01

    Previous studies by the authors have determined pavement responses under dynamic loading consid-ering cross-anisotropy in one layer only, either the cross-anisotropic viscoelastic asphalt concrete (AC) layer or the cross-anisotropic stress-dependent base layer, but not both. This study evaluates pavement stressestrain responses considering cross-anisotropy in all layers, i.e. AC, base and subbase, using finite element modeling (FEM) technique. An instrumented pavement section on Interstate I-40 near Albu-querque, New Mexico was used in ABAQUS framework as model geometry. Field asphalt cores were collected and tested in the laboratory to determine the cross-anisotropy (n-values) defined by horizontal to vertical modulus ratio, and other viscoelastic parameters as inputs of the model incorporated through user defined material interface (UMAT) functionality in ABAQUS. Field base and subbase materials were also collected and tested in the laboratory to determine stress-dependent nonlinear elastic model pa-rameters, as inputs of the model, again incorporated through UMAT. The model validation task was carried out using field-measured deflections and strain values under falling weight deflectometer (FWD) loads at the instrumented section. The validated model was then subjected to an actual truck loading for studying cross-anisotropic effects. It was observed that horizontal tensile strain at the bottom of the AC layer and vertical strains in all layers decreased with an increase in n-value of the asphalt layer, from n<1 (anisotropy) to n ¼ 1 (isotropy). This indicates that the increase in horizontal modulus caused the decrease in layer strains. It was also observed that if the base and subbase layers were considered stress-dependent instead of linear elastic unbound layers, the horizontal tensile strain at the bottom of the asphalt layer increased and vertical strains on top of the base and subbase also increased.

  6. Construction of an experimental sulfur-extended-asphalt pavement

    Science.gov (United States)

    Dodge, K. S.

    1982-07-01

    The design, placement and collection of initial data from a sulfur extended asphalt (SEA) pavement and a conventional pavement used as a control is documented. The SEA pavement used 30 percent sulfur by total weight of the binder. Mix temperatures, hot bin gradations, and toxic emissions were monitored at the plant and the site throughout placement. Aggregates were collected from the hot bin during production of the control and SEA mixes for use in a Marshall mix design. Cores were extracted from both SEA and control pavements 1 month after placement for laboratory testing. Pavement surface properties were also examined after 1 month of service.

  7. Formative Evaluations of a Web-Based Masters Program: Insights for Web-Based Course Developers.

    Science.gov (United States)

    Shih, Ching-Chun; Howard, Marvin; Thompson, Ann D.

    The purpose of this paper is to report on the various formative evaluation activities that have been conducted for the Masters of Science in Agronomy Distance Education Program at Iowa State University and to provide useful recommendations for educators involved in World Wide Web-based course development. It was found that those faculty members…

  8. System Identification Method for Evaluating the Effect of Thickness Error on Backcalculated Pavement Layer Moduli

    Institute of Scientific and Technical Information of China (English)

    ZHONG Yan-hui; WANG Fu-ming; ZHANG Bei; CAI Ying-chun

    2004-01-01

    Based on system identification theory and FWD testing data, the effect of thickness error on backcalculating pavement layer moduli is studied and the method of singular value decomposition (SVD) is presented to solve the morbidity problem of sensitivity matrix in this paper.The results show that the thickness error has great effects on the backcalculated pavement layer moduli. The error of backcalculated moduli can be controlled within the range of ±15% by limiting the thickness error within the range of ±5%.

  9. Construction and Preliminary HVS Tests of Pre-Cast Concrete Pavement Slabs

    OpenAIRE

    Kohler, Erwin R.; du Plessis, Louw; Theyse, Hechter

    2008-01-01

    This report presents the details on the construction and preliminary load tests on an experimental pavement comprised of ten pre-cast slabs of the pavement known as the Super-Slab® System, installed at the intersection of I-15 and SR210, in San Bernardino County in southern California. The construction of the test section consisted of: (a) Construction of a cement-treated base (CTB), (b) Preparation of a sand bedding layer, (c) Placement of the pre-cast slabs, (d) Application of grout materi...

  10. CDIO Based Optimization of Urban Planning Personnel Training Courses in Forestry Universities

    Institute of Scientific and Technical Information of China (English)

    Ming; SUN; Jun; ZHANG; Jun; DONG; Bing; CHANG

    2014-01-01

    On the basis of analyzing existing course system of urban planning discipline,this paper came up with a framework for optimization of urban planning personnel training mode and course system,oriented towards training practical engineering personnel and based on CDIO engineering education and teaching platform. Then it made empirical study on setting of the urban planning discipline in Northeast Forestry University. It proposed changing the original "3 + 2" course system,exploring and optimizing the course system,improving teaching effect of urban planning personnel training courses,and raising planning and design ability of students.

  11. Statmaster and HEROS - web-based courses first and second generation

    DEFF Research Database (Denmark)

    Larsen, Pia Veldt; Rootzen, Helle

    2008-01-01

    With the increasing focus on life-long learning, and with the convenience and accessibility of the Internet, the market for web-based courses has expanded vastly in recent times–in particular in connection with continuing education. However, teaching web-based courses presents various technical as...... well as pedagogical challenges. Some of these challenges are addressed, and means to dealing with them are suggested. A second generation of web-based courses is comprised of learning objects, which allows for tailoring courses for specialized groups of students, and accommodate individualized learning...

  12. Evaluation of clay content in soils for pavement engineering applications using GPR

    Science.gov (United States)

    Tosti, Fabio; Patriarca, Claudio; Benedetto, Andrea; Slob, Evert C.; Lambot, Sébastien

    2013-04-01

    Clay content significantly influences the mechanical behavior of soils, thereby playing an important role in many fields of applications such as civil engineering, geology and agriculture. In the area of pavement engineering, clay content in structural bearing courses of pavement frequently causes damages and defects, such as transversal and longitudinal cracks, or other faults. The main consequence is a lowering of both the road safety and operability, with the number of expected accidents increasing. In this study, ground-penetrating radar (GPR) laboratory tests were carried out to predict the clay amount in pavement structural layers under different clay and moisture conditions. GPR data processing is performed using two different methods. The first method is based on the Fresnel theory and focuses on the Rayleigh scattering of the radar waves. The approach is based on a different scattering of the various components of the frequency spectrum, mostly depending on both the soil texture and variation in soil moisture content. For the application of this method, we used a pulse radar with ground-coupled, 500 MHz centre-frequency antennas in a common offset, bistatic configuration. The transmitter and receiver were linked by optic fiber electronic modules. The second method is based on full-waveform inversion of the ultra wideband radar data. In particular, a specific radar-antenna electromagnetic model is used to filter out antenna effects and antenna-medium interactions from the raw radar data and retrieve the response of the soil only, expressed in terms of a layered medium Green's function. To estimate the medium geometrical and electrical values, an optimization inverse problem is formulated. For the application of that second method, we used a vector network analyzer (VNA) as continuous-wave stepped-frequency radar system to acquire data in the 500-3000 MHz frequency range. A doubled-ridged broadband horn antenna operating in far-field conditions was used as

  13. Nanotechnology and Society: A discussion-based undergraduate course

    Science.gov (United States)

    Tahan, Charles; Leung, Ricky; Zenner, G. M.; Ellison, K. D.; Crone, W. C.; Miller, Clark A.

    2006-05-01

    Nanotechnology has emerged as a broad, exciting, yet ill-defined field of scientific research and technological innovation. There are important questions about the technology's potential economic, social, and environmental implications. We discuss an undergraduate course on nanoscience and nanotechnology for students from a wide range of disciplines, including the natural and social sciences, the humanities, and engineering. The course explores these questions and the broader place of technology in contemporary societies. The course is built around active learning methods and seeks to develop the students' critical thinking skills, written and verbal communication abilities, and general knowledge of nanoscience and nanoengineering concepts. Continuous assessment was used to gain information about the effectiveness of class discussions and enhancement of student understanding of the interaction between nanotechnology and society.

  14. The Design of a Web-Based Course for Self-Directed Learning

    Science.gov (United States)

    Liu, Mingzhuo

    2009-01-01

    Purpose: The purpose of this paper is to explore how to design a web-based course in the context of China for self-directed learning from four perspectives--i.e. pedagogical, psychological, social and technological--and also to summarize the design principles for the web-based course. Design/methodology/approach: The paper reviews literature…

  15. Effects of a Case-Based Reasoning System on Student Performance in a Java Programming Course

    Science.gov (United States)

    Schmidt, Cecil

    2007-01-01

    The purpose of this study was to determine if a case-based reasoning tool would improve a student's understanding of the complex concepts in a Java programming course. Subjects for the study were randomly assigned from two sections of an introductory Java programming course. Posttests were used to measure the effects of the case-based reasoning…

  16. Effectiveness of an e-learning course in evidence-based medicine for foundation (internship) training

    NARCIS (Netherlands)

    J. Hadley; R. Kulier; J. Zamora; S.F. Coppus; S. Weinbrenner; B. Meyerrose; T. Decsi; A.R. Horvath; E. Nagy; J.I. Emparanza; T.N. Arvanitis; A. Burls; J.B. Cabello; M. Kaczor; G. Zanrei; K. Pierer; R. Kunz; V. Wilkie; D. Wall; B.W. Mol; K.S. Khan

    2010-01-01

    Aim To evaluate the educational effectiveness of a clinically integrated e-learning course for teaching basic evidence-based medicine (EBM) among postgraduate medical trainees compared to a traditional lecture-based course of equivalent content. Methods We conducted a cluster randomized controlled t

  17. Using the 4MAT Framework to Design a Problem-Based Learning Biostatistics Course

    Science.gov (United States)

    Nowacki, Amy S.

    2011-01-01

    The study presents and applies the 4MAT theoretical framework to educational planning to transform a biostatistics course into a problem-based learning experience. Using a four-question approach, described are specific activities/materials utilized at both the class and course levels. Two web-based instruments collected data regarding student…

  18. The Impact of an Inquiry-Based Geoscience Field Course on Pre-Service Teachers

    Science.gov (United States)

    Nugent, Gwen; Toland, Michael D.; Levy, Richard; Kunz, Gina; Harwood, David; Green, Denise; Kitts, Kathy

    2012-01-01

    The purpose of this quasi-experimental study was to determine the effects of a field-based, inquiry-focused course on pre-service teachers' geoscience content knowledge, attitude toward science, confidence in teaching science, and inquiry understanding and skills. The field-based course was designed to provide students with opportunities to…

  19. Explore the Human-Based Teaching for the Professional Course of Materials Science and Engineering

    Science.gov (United States)

    Zhao, Yiping; Chen, Li; Zhang, Yufeng

    2008-01-01

    As viewed from two sides such as teacher and student, in this article, we explore the human-based teaching reform for the college professional course of materials Science and Engineering, point out the qualities and conditions that professional teacher should possess in the process of human-based teaching reform of professional course and the…

  20. ATB基层的合理模量和厚度范围研究%Research on Reasonable Modulus and Thickness Range of ATB Base Course

    Institute of Scientific and Technical Information of China (English)

    赵晓玲

    2012-01-01

    采用Bisar3.0程序对设置ATB柔性基层的沥青路面结构进行力学响应分析,分析各结构层层底最大拉应力随ATB层厚度和模量的变化趋势。结果表明,上面层、下面层和基层的层底最大拉应力随ATB模量和厚度的增大而增大;中面层的层底最大拉应力随ATB层厚度的增大、模量的降低而增大;底基层的层底最大拉应力随ATB模量和厚度的增大而减小;根据各结构层层底最大拉应力的分析结果和2100万交通轴载作用寿命下的要求,综合推荐ATB层的合理厚度范围为6~14cm、合理模量范围为1000~1400MPa。%Mechanical response analysis is conducted on the structure of asphalt pavement with ATB flexible base course with Bisar3.0. The change trend of maximum tensile stress of each structure layer bottom along with the thickness and modulus of ATB layer is analyzed. The result shows that the maximum tensile stress of bottom of up- per surface, lower surface and base course increases with the increase of modulus and thickness of ATB ; the maxi- mum tensile stress of bottom of middle surface increases with the increase of thickness and decrease of modulus of ATB ; the maximum tensile stress of bottom of subbase course decreases with the increase of modulus and thickness of ATB ; According to the analysis result on the maximum tensile stress of bottom of each structure layer and re- quirements for service life under 21,000,000 traffic axial load, the reasonable thickness range is comprehensively recommended to be 6cm N 14cm and reasonable modulus range to be 1000MPa - 1400MPa for ATB base course.

  1. Developing a project-based computational physics course grounded in expert practice

    CERN Document Server

    Burke, Christopher

    2016-01-01

    We describe a project-based computational physics course developed using a backwards course design approach. From an initial competency-based model of problem solving in computational physics, we interviewed faculty who use these tools in their own research to determine indicators of expert practice. From these, a rubric was formulated that enabled us to design a course intended to allow students to learn these skills. We also report an initial implementation of the course and, by having the interviewees regrade student work, show that students acquired many of the expert practices identified.

  2. 基于入渗产流分析的透水砖地面铺装结构试验%Experimental study on pavement structure of pervious bricks based on infiltration and nmoff generation analysis

    Institute of Scientific and Technical Information of China (English)

    张书函; 陈建刚; 赵飞; 侯立柱

    2011-01-01

    In order to find pervious pavement structures in favor of rainfall infiltration and runoff reduction, the characteristics of the rainfall infiltration and runoff generation in the pervious pavements with different structures were studied by means of artificial rainfall experiments. According to the comparison of performances of runoff reduction, infiltration increase and runoff generation lagging among 8 kinds of pavement structures, the optimal pavement structure should be the mode of " pervious brick and concrete without sand and single gradation gravel" from top to bottom.%为了找出有利于降雨入渗、削减径流的透水地面铺装结构,通过人工降雨试验,研究不同铺装垫层结构透水地面的降雨入渗与产流特性.根据8种铺装结构在径流削减、入渗量增加、开始产流时间滞后等方面的效果比较,推荐透水砖地面自上而下的铺装结构为“透水砖面层+无砂混凝土+单级配碎石”形式.

  3. 基于土工合成材料加铺层的沥青混凝土路面抗裂性能%Crack Resistance of Geosynthetics Overlay Based Asphalt Concrete Pavement

    Institute of Scientific and Technical Information of China (English)

    孙雅珍; 刘杰民; 赵复笑

    2012-01-01

    应用数值计算的方法和冲击韧性试验研究在行车载荷作用下土工合成材料加铺层对含反射裂缝沥青混凝土路面的抗裂效果,并对土工合成材料弹性模量进行了优化设计.分析了温度、时间和加铺层弹性模量对裂缝延长线上各点正应力和面层层底拉应力的影响;应用冲击韧性试验系统评价了土工合成材料加铺层的抗裂效果.数值计算与冲击韧性试验结果基本一致.研究结果表明:铺设土工合成材料是防治反射裂缝的有效途径,能有效地改变结构的应力分布,更大程度地减少了应力集中;同时确定最佳的土工布加铺层的弹性模量为1 000 MPa;但加铺层对含裂缝沥青混凝土路面的路表弯沉基本没有影响.%The effect of geosynthetics overlay on retarding propagation of reflective cracks in AC pavement under vehicle load was studied by numerical calculation and impact toughness test, and the modulus of geosynthetics overlay was optimized. The effects of temperature, time and elastic modulus of the geosynthetics overlay on the tensile stress at the bottom of surface course and the normal stresses on the line of extensional crack-tip were analyzed. The impact toughness test was conducted to evaluate the effectiveness of the crack resistance of the geosynthetics overlay. The numerical calculation result was consistency with the test result. The results show that (1) geosynthetics overlay is effective for reflective crack resistance, it could obviously decrease stress concentration and change stress distribution; (2 ) the elastic modulus of the optimum geosynthetics overlay is 1 000 Mpa; (3) the geosynthetics overlay basically has no effect on the vertical deflection of the road surface.

  4. Permeable pavement research – Edison, New Jersey

    Science.gov (United States)

    These are the slides for the New York City Concrete Promotional Council Pervious Concrete Seminar presentation. The basis for the project, the monitoring design and some preliminary monitoring data from the permeable pavement parking lot at the Edison Environmental Center are pre...

  5. Development of New Bituminous Pavement Design Method

    DEFF Research Database (Denmark)

    Ullidtz, Per

    The report and work of COST Action 333 sets in place the foundation for a coherent, cost-effective and harmonised European pavement design method. In order to do this, the work programme focused on information gathering, identification of requirements and the selection of the necessary design...

  6. Viscoelastic Pavement Modeling with a Spreadsheet

    DEFF Research Database (Denmark)

    Levenberg, Eyal

    2016-01-01

    The aim herein was to equip civil engineers and students with an advanced pavement modeling tool that is both easy to use and highly adaptive. To achieve this, a mathematical solution for a layered viscoelastic half-space subjected to a moving load was developed and subsequently implemented...

  7. Teaching Academic Skills in Content-based Courses

    OpenAIRE

    Evelyn J,NAOUMI

    2010-01-01

    This papers the result of one teacher's reflections about her teaching and uses qualitative data drawn from weekly student reflections on the class and student end of course self evaluations to illustrate her experience. Some of this material has appeared in a joint paper published with a collaborative teacher.

  8. Web-Based Interactive Visualization in an Information Retrieval Course.

    Science.gov (United States)

    Brusilovsky, Peter

    Interactive visualization is a powerful educational tool. It has been used to enhance the teaching of various subjects from computer science to chemistry to engineering. In computer science education, this powerful tool is used almost exclusively in programming and data structure courses. This paper suggests that visualization could be very…

  9. A Web-Based Course of Lectures in Respiratory Physiology

    Science.gov (United States)

    West, John B.

    2011-01-01

    A complete course of respiratory physiology suitable for first-year medical and graduate students has been placed on the Web for our own students and for other educational institutions. There are several reasons for doing this. The first is that the modern-day student uses a variety of options for acquiring knowledge. These include attending…

  10. Developing a course in nuclear reactor modelling and going from campus-based to web-based teaching

    International Nuclear Information System (INIS)

    This paper presents the development of a course in nuclear reactor modelling at Chalmers University of Technology in Gothenburg, Sweden. This course, part of an international master program in nuclear engineering, deals with the modelling of deterministic neutron transport, fluid dynamics, and heat transfer in nuclear cores. The objective of the course is to present the methods applied in the simulation tools used by the industry for both steady-state and transient calculations. The originality of the course lies with the fact that all the above fields are tackled in a single course and that all the fundamental algorithms, together with their approximations and limitations, are detailed. The paper also reports on a web-based teaching framework lately adopted for the course. In this configuration, the course was entirely based on using the web for all lectures, tutorials, examination, and communication with the teaching staff. All course materials were accessible on the web to all students at any time, with the lectures recorded in advance and the tutorials live broadcasted and also available for on-demand viewing. The on-site students also had the possibility to attend the tutorials in a classical campus-based teaching set-up. An evaluation of the web-based teaching methods was made possible by the fact that the course was earlier run in a campus-based format. Despite a limited number of students making difficult to draw any systematic conclusions, a deeper learning to the course concepts was perceived. (author)

  11. Analysis on Dynamic Response of Saturated Asphalt Pavement under Moving Vehicle Loads by 3D Finite Element Method%移动荷载作用下饱和沥青路面动力响应三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    任瑞波; 祁文洋; 李美玲

    2011-01-01

    Asphalt pavement is a kind of porous medium which consists of solid, liquid and gas phases under the action of outside environment. The coupled hydro-mechanical action leads to the initial failure of asphalt pavement. To explore the dynamic response of asphalt pavement subjected to moving vehicle loads is the premise for understanding the structure behavior of asphalt pavement. First, regarding asphalt mixture as a media consists of solid and liquid phases in level one reasonable approximation, based on the porous media theory, a 3D finite element model of typical semi-rigid base asphalt concrete pavement under moving load was developed in the assumption that the asphalt pavement is saturated. Then, the variation of 3D strain and stress as well as 3D distribution of vertical stress of pavement under saturated condition and dry condition were comparatively analysed. The result indicates that (1) the characteristics of dynamic response of asphalt pavement with moving load under saturated condition and dry condition in surface course are different; (2) it' is more likely to have structure damage such as fatigue cracking and permanent deformation when asphalt pavement is under saturated condition; (3) in asphalt pavement design, it is more reasonable to use flexural-tensile strain as the index than flexural-tensile stress.%沥青路面结构在外界环境作用下是气、液、固三相介质体,水和荷载的耦合作用导致了沥青路面初期损坏的产生,探究其在车辆移动荷栽作用下的动力响应是获知沥青路面结构行为的前提.首先,在沥青路面饱和情况下,作一级合理近似,将其视为流固两相介质.基于多孔介质理论,对于典型半刚性基层沥青路面结构建立了移动荷载作用下的三维有限元模型;而后对比分析了移动荷载作用下,饱和沥青路面和无水沥青路面三向应力、应变响应的时程变化规律以及竖向应力场的三维分布情况.结果表明:移动荷载

  12. Bearing capacity evaluation of rubblized concrete pavements

    Directory of Open Access Journals (Sweden)

    González, M.

    2009-03-01

    Full Text Available The paper presents the findings of a research work performed on a real scale concrete pavement project where Rubblizing technology was used for its structural rehabilitation. Rubblizing may be defined as a fracture technique in which a concrete pavement slab is transformed in a granular base with a very high Modulus. This technique, fractures the concrete slab in angular pieces by using a concentrated dynamic load of low amplitude and high frequency. The research work was based on field study on the rehabilitation of 5 km motorway. The structural evaluations where made, before, during and after one year construction. Measurements and site evaluation where made by using DCP, Light Weight Deflectometer and FWD (on top of asphalt layer and excavating inside pits. The structural capacity of the Rubblized layer was evaluated through theoretical analysis. Because of the anisotropic properties of the Rubblized layer the results are presented using AASHTO structural layer coefficient. The structural layer coefficients recommended are between the range of 0.25 and 0.30 for concrete slabs with thickness grater than 220 mm.El trabajo presenta los resultados de un estudio a escala real de la capacidad estructural de un firme de hormigón rehabilitado utilizando la técnica de Rubblizing. La técnica de Rubblizing ha sido traducida como el pulverizado del firme de hormigón pero, es más bien un efecto combinado de trituración y fracturación de la losa de hormigón en todo su espesor para convertir esta en una base granular de alto módulo. Esta tecnica fractura la losa de hormigón en trozos angulares y entrelazados empleando una carga dinámica concentrada, de baja amplitud y alta frecuencia. La investigación se basó en el estudio de la rehabilitación de 5 km de autopista. Los estudios de la capacidad estructural fueron realizados durante, al término y un año después de la construcción. Para las mediciones y evaluaciones de terreno se utilizó, el

  13. 层间接触位置和状态对沥青路面力学指标的影响%Influence of Interlayer Contacting Surface and Condition on Mechanical Indexes of Asphalt Pavement

    Institute of Scientific and Technical Information of China (English)

    张争奇; 张苛; 罗要飞

    2015-01-01

    In order to study the influence of interlayer contacting surfaces and condition on me-chanical index of asphalt pavement,the paper selected typical semi-rigid base pavement structure of ex-pressway.The pavement mechanical indexes under different contacting surface were calculated by BISAR 3.0.The changing laws of asphalt pavement mechanical indexes and fatigue life under different contac-ting condition between base and surface course were discussed.The results show that:the influence of smooth condition between surface courses,surface course and base,base and subbase on tensile stress, tensile strain and shear stress is prominent.Deflection is slightly affected by different interlayer contacting surface.The stress and strain of pavement increase gradually with the increasing of sliding coefficient be-tween base and surface course.The tensile stress,shear stress and tensile strain of following layer under completely sliding condition are 2.93 times,2.45 times and 69.36 times of fully continuous condition re-spectively.Decreasing range of fatigue life is small when the sliding coefficient between base and surface course is less than 0.6,then decreasing range increases.When the base and surface course are in com-pletely smooth,the fatigue life declines 44.5%.%为研究沥青路面层间接触位置和接触状态对路面结构内力学指标的影响,选择典型的高速公路半刚性基层路面结构,利用 BISAR3.0软件计算分析不同层间接触位置时的路面力学指标,并探讨不同基面层接触状态下沥青路面力学响应和疲劳寿命的变化规律。结果表明:面层与面层、面层与基层、基层与底基层之间在完全光滑时对拉应力、拉应变、剪应力影响显著,弯沉受层间接触位置的影响变化不大;随着基面层间滑动系数的增加,路面结构内的应力、应变逐渐增大,在完全滑动时下面层底的拉应力、剪应力和拉应变分别是完全连续时的2.93倍、2

  14. Grey Relational Analysis of Fatigue Property of Pavement Structure of Inverted Flexible Base%倒装式桑性基层路面结构疲劳性能灰关联分析

    Institute of Scientific and Technical Information of China (English)

    张悦; 周举成

    2012-01-01

    利用有限元软件建立多个不同的倒装式路面结构模型进行计算,并将计算结果导入到nSoft软件进行疲劳分析,得到不同倒装式路面结构模型的抗疲劳性能。根据灰色关联分析理论,对得到的不同倒装式路面结构的抗疲劳性能进行灰关联分析,得出各倒装式路面结构参数对倒装式路面结构抗疲劳性能影响程度的依次顺序。研究结论对以提高倒装式路面结构抗疲劳性能为目标的路面结构调整有一定的指导作用。%Finite element software is used to establish many different inverted pavement structural models to perform calculation and lead the calculation results into nSoft to perform fatigue analysis. Therefore, anti -fatigue properties of different inverted pavement structural models are obtained. According to grey relational analysis theory, the analysis is performed on the anti - fatigue properties of different models and proper sequence of the influence degree of various inverted pavement structural parameters on anti - fatigue property is gained. The research conclusion has certain instruction function to the adjustment of the inverted pavement structure into targeted pavement structure through improving anti -fatigue property.

  15. Primary research on emulsified asphalt cold recycled mixture added recycled materials of base course%乳化沥青复合冷再生混合料研究

    Institute of Scientific and Technical Information of China (English)

    任瑞波; 朱树青; 徐强; 马川义

    2015-01-01

    路面基层废旧料的研究利用可节约工程建设成本,缓解路面养护带来的资源和环境压力。文章通过对路面基层与面层废旧材料分析与设计,确定最佳含水率与合适沥青用量,通过劈裂试验和冻融试验,评价掺加基层废旧料的乳化沥青复合冷再生混合料的性能。结果表明:矿料类型对乳化沥青冷再生混合料最佳含水率和劈裂强度影响较大;在低油量范围内,掺加基层废旧料的乳化沥青复合冷再生混合料劈裂强度较高,具有一定的抗弯拉能力和抗水损害能力,抗冻融能力一般;乳化沥青复合冷再生混合料具有感温性,属于粘弹性材料;掺加基层废旧料乳化沥青复合冷再生混合料性能够基本满足再生技术规范使用要求。%The utilization of old base course materials could save the cost of engineering construction and ease the pressure for resources and environment in pavement maintenance. Based on these,the research on RAP of base course was conducted. Material analysis and grade design were executed to determine the optimum moisture content and appropriate asphalt content and relatively performance tests were carried out under the optimum moisture and suitable asphalt content. Tests results show that mineral aggregate type of emulsified asphalt cold recycled mixture had a greater influence on the best moisture content and the splitting strength;emulsified asphalt cold recycled mixture mixed with the materials of base course has certain flexural tensile strength to resistant bending and water damage;the ability of mixture is normal to resist freezing and thawing;the composite materials is sensitive to temperature which said it belong to viscous-elastic material;the composite materials meet technical requirement of cold recycled mixture using on lower layers of pavement.

  16. Lessons Learned from Undergraduate Students in Designing a Science-Based Course in Bioethics

    OpenAIRE

    Loike, John D.; Rush, Brittany S.; Schweber, Adam; Fischbach, Ruth L.

    2013-01-01

    Columbia University offers two innovative undergraduate science-based bioethics courses for student majoring in biosciences and pre–health studies. The goals of these courses are to introduce future scientists and healthcare professionals to the ethical questions they will confront in their professional lives, thus enabling them to strategically address these bioethical dilemmas. These courses incorporate innovative pedagogical methods, case studies, and class discussions to stimulate the stu...

  17. A comparison of student characteristics in traditional and Web-based college science courses

    Science.gov (United States)

    Andrikanich, Meghan

    Distance learning options at colleges and universities are increasing dramatically (e.g. National Center for Educational Statistics [NCES], 1998; NCES, 2001). Web-based courses create an interesting learning environment for study (e.g., Dupin-Bryant, 2004; Maki & Maki, 2003). Because science is a topic that induces anxiety for many students (e.g., Brownlow, et al., 2000; Greenburg & Mallow, 1982), and test anxiety has been linked to reduced academic performance (e.g., Bruch, 1981; Spielberger, 1979), the intersection of course format, science, and test anxiety is an area in need of research. This study used an explanatory mixed method design. One hundred and seven web-based science students and 110 students enrolled in traditional courses completed a questionnaire regarding demographic and personal factors, the Reduced Reaction to Tests (RTT) (Benson & Bandalos, 1992) and the Locus of Control of Behavior Scale (Craig, Franklin, & Andrews, 1984). Ten students participated in a follow-up interview. Quantitative results found no significant difference between age, racial/ethnic background, student status (full-time or part-time), or degree program being pursued between traditional and web-based science courses. Significantly more females, more students employed full-time, and with an external locus of control enrolled in web-based courses. Students in traditional courses experienced more test anxiety due to test-irrelevant thoughts. Traditional students experienced more anxiety in traditional science courses, while nontraditional students experienced more anxiety in web-based science courses. Expected course grade and locus of control predicted test anxiety in traditional courses, and previous web experience, expected grade, and locus of control predicted test anxiety for web-based courses. Qualitative data indicated that students in both formats expressed opinions regarding course format, studying and test preparation methods, test-taking, communication with

  18. 融沉变形对柔性路面应力应变影响试验研究%Influence of thawing settlement deformation on stress and strain in flexible pavement

    Institute of Scientific and Technical Information of China (English)

    钟勇强; 黄晓明; 廖公云; 路畅; 何平

    2011-01-01

    为了研究多年冻土地区路基融沉变形对柔性路面力学性能的影响,采用松铺土和埋设工业冰块2种冻土路基融沉变形模拟方法,修建室内大尺度柔性路面结构试槽并逐层埋设传感器.采用承载板试验方法进行柔性路面面层和基层应力应变检测,通过检测数据的分析得出了融沉变形对柔性路面应力应变的影响规律.结果表明:松铺土测点和埋设工业冰块测点面层与基层层底应变相比正常测点均显著提高,融沉测点面层比正常测点承受了更多的压应力.融沉变形对各层层底应变特别是基层层底应变的非线性特征影响较大,幂函数可以很好地描述其非线性变化规律.研究成果将为冻土地区柔性路面设计提供参考.%In order to study the influence of subgrade thawing settlement deformation on the mechanical properties of flexible pavement in permafrost region, two thawing settlement deformation simulation methods of frozen soil subgrade, i.e. loose paving soil and burying industrial ice block, were adopted. Laboratory large-scale experiment tank of flexible pavement structure was built and transducers were buffed layer by layer. The stress and strain detection of flexible pavement surface course and base course were carried out by bearing plate test method. Through the analysis of detection data, the influence law of thawing settlement deformation on stress and strain of flexible pavement was obtained. The results show that the bottom strain of surface course and base course of loose paving soil and burying industrial ice block measuring points are both significantly increased compared to the normal measuring points. The surface course of thawing settlement measuring point bears more stress than the surface course of normal measuring point. Thawing settlement deformation has a larger effect on nonlinear characteristics of strain in layers bottom especially bottom of base course. Power function can well

  19. Nanotechnology and Society A discussion-based undergraduate course

    CERN Document Server

    Tahan, C; Zenner, G M; Ellison, K D; Crone, W C; Miller, C A; Tahan, Charles; Leung, Ricky; Miller, Clark A.

    2006-01-01

    Nanotechnology has emerged as a broad and exciting, yet ill-defined, field of scientific research and technological innovation. Important questions have arisen about the technology's potential economic, social, and environmental implications by prominent technology leaders, nanotechnology boosters, science fiction authors, policy officials, and environmental organizations. We have developed an undergraduate course that offers an opportunity for students from a wide range of disciplines, including the natural and social sciences, humanities, and engineering, to learn about nanoscience and nanotechnology, to explore these questions, and to reflect on the broader place of technology in modern societies. The course is built around active learning methods and seeks to develop the students' critical thinking skills, written and verbal communication abilities, and general knowledge of nanoscience and nanoengineering concepts. Continuous assessment was used to gain information about the effectiveness of class discuss...

  20. 垃圾焚烧灰渣用于二灰碎石路面基层的试验研究%Experiment on Wastes Incineration Residues for Lime-Fly Ash Concrete Pavement Base

    Institute of Scientific and Technical Information of China (English)

    解建光; 陈金东; 曹兴国; 史进舟

    2011-01-01

    By replacing a part of macadam, wastes incineration residues used as aggregates to make lime-fly ash stabilized residues-macadam materials are conducted at nine different proportions. Compaction test , unconfined compressive strength test and shrinkage test are designed to evaluate the pavement performances of the material. Furthermore, the comparative trials are conducted between the new materials and traditional lime-fly ash macadam at the same proportions. Comparing with the traditional lime-fly ash macadam, the maximum dry density decreases by 8. 8% and the optimum water content increases by 38. 4% at the same content of lime and fly ash. Besides, the highest unconf ined compressive strength of lime-fly ash stabilized residues-macadam can reach 1-03 MPa, and the strengths of the new materials are significantly influenced by the content of fly ash. The strength decrease by 21%, if the content of fly ash decreases by 1%. The highest shrinkage coefficient is 67. 2 μ%, and if the content of lime and fly ash decreases by 2.55% the shrinkage coefficient reduces by 3. 1%. The performances of lime-fly ash stabilized residues-macadam can meet the requirements of highway pavement base, and combustion residues can be used as aggregates in road construction.%用城市生活垃圾焚烧灰渣替代部分集料,按照9种不同的配比制备二灰灰渣碎石路面基层材料,进行路用性能试验.结果表明:与普通二灰碎石对比,在相同的二灰含量下,灰渣碎石的最大干密度降低8.8%,而最佳含水量增大38.4%;无侧限抗压强度最高可达1.03 MPa;粉煤灰含量对材料强度影响较为显著,其中粉煤灰含量减少1%,无侧限抗压强度值降低21%;材料的干缩系数最大为67.2μ/%;石灰与粉煤灰含量越低,材料的干缩应变越小,平均干缩系数也越小,当二灰含量减少2.5%,平均干缩系数降低3.1%.二灰灰渣碎石材料满足基层的相关要求,灰渣可以为公路建设提供可持续的集料来源.

  1. Teaching Research Methodology Using a Project-Based Three Course Sequence Critical Reflections on Practice

    Science.gov (United States)

    Braguglia, Kay H.; Jackson, Kanata A.

    2012-01-01

    This article presents a reflective analysis of teaching research methodology through a three course sequence using a project-based approach. The authors reflect critically on their experiences in teaching research methods courses in an undergraduate business management program. The introduction of a range of specific techniques including student…

  2. Drugs, Devices, and Desires: A Problem-Based Learning Course in the History of Medicine

    Science.gov (United States)

    Levitt, Sarah; McKeage, Anne; Rangachari, P. K.

    2013-01-01

    Problem-based learning (PBL) is well suited for courses in the history of medicine, where multiple perspectives exist and information has to be gleaned from different sources. A student, an archivist, and a teacher offer three perspectives about a senior level course where students explored the antecedents and consequences of medical technology.…

  3. A Theme-Based Course: Hydrogen as the Fuel of the Future

    Science.gov (United States)

    Shultz, Mary Jane; Kelly, Matthew; Paritsky, Leonid; Wagner, Julia

    2009-01-01

    A theme-based course focusing on the potential role of hydrogen as a future fuel is described. Numerous topics included in typical introductory courses can be directly related to the issue of hydrogen energy. Beginning topics include Avogadro's number, the mole, atomic mass, gas laws, and the role of electrons in chemical transformations. Reaction…

  4. Known Structure, Unknown Function: An Inquiry-Based Undergraduate Biochemistry Laboratory Course

    Science.gov (United States)

    Gray, Cynthia; Price, Carol W.; Lee, Christopher T.; Dewald, Alison H.; Cline, Matthew A.; McAnany, Charles E.; Columbus, Linda; Mura, Cameron

    2015-01-01

    Undergraduate biochemistry laboratory courses often do not provide students with an authentic research experience, particularly when the express purpose of the laboratory is purely instructional. However, an instructional laboratory course that is inquiry- and research-based could simultaneously impart scientific knowledge and foster a student's…

  5. Impact Assessment of Problem-Based Learning in an Engineering Science Course

    Science.gov (United States)

    Nasr, Karim J.; Ramadan, Bassem H.

    2008-01-01

    This paper presents the development and implementation of Problem-Based Learning (PBL) in an engineering thermodynamics course at Kettering University. In this project, the thermodynamics course was restructured as modules presenting practical applications first, whereas principles were introduced just-in-time and as encountered. Theoretical…

  6. A Wiki-Based Group Project in an Inorganic Chemistry Foundation Course

    Science.gov (United States)

    Kristian, Kathleen E.

    2015-01-01

    A semester-long group project that utilizes wiki sites to enhance collaboration was developed for a foundation course in inorganic chemistry. Through structured assignments, student groups use metal-based or metal-combating therapeutic agents as a model for applying and understanding course concepts; they also gain proficiency with scientific- and…

  7. Web-Based Social Work Courses: Guidelines for Developing and Implementing an Online Environment

    Science.gov (United States)

    Dawson, Beverly Araujo; Fenster, Judy

    2015-01-01

    Although web-based courses in schools of social work have proliferated over the past decade, the literature contains few guidelines on steps that schools can take to develop such courses. Using Knowles's framework, which delineates tasks and themes involved in implementing e-learning in social work education, this article describes the cultivation…

  8. Transitioning from Expository Laboratory Experiments to Course-Based Undergraduate Research in General Chemistry

    Science.gov (United States)

    Clark, Ted M.; Ricciardo, Rebecca; Weaver, Tyler

    2016-01-01

    General chemistry courses predominantly use expository experiments that shape student expectations of what a laboratory activity entails. Shifting within a semester to course-based undergraduate research activities that include greater decision-making, collaborative work, and "messy" real-world data necessitates a change in student…

  9. An Ill-Structured PBL-Based Microprocessor Course without Formal Laboratory

    Science.gov (United States)

    Kim, Jungkuk

    2012-01-01

    This paper introduces a problem-based learning (PBL) microprocessor application course designed according to the following strategies: 1) hands-on training without having a formal laboratory, and 2) intense student-centered cooperative learning through an ill-structured problem. PBL was adopted as the core educational technique of the course to…

  10. The Impact of Task-Based Approach on Vocabulary Learning in ESP Courses

    Science.gov (United States)

    Sarani, Abdullah; Sahebi, Leila Farzaneh

    2012-01-01

    This study investigates the teaching of vocabulary in ESP courses within the paradigm of task-based language teaching, concentrating on Persian literature students at Birjand University in Iran. Two homogenous groups of students who were taking their ESP courses participated in the study as a control and an experimental group. A teacher-made test…

  11. Computer Controlled Test Systems. Introduction. A Course Based on the IEEE 488 Bus.

    Science.gov (United States)

    Herrmann, Eric J.

    An introductory course in computer automated tests and measurement systems based on the International Test Instrument-Computer Interface Standard, the IEEE (Institute of Electrical and Electronics Engineers)-488, is presented in this study guide. This course is designed to: (1) introduce the electronics engineering technician to the functional…

  12. The Views of Undergraduates about Problem-Based Learning Applications in a Biochemistry Course

    Science.gov (United States)

    Tarhan, Leman; Ayyildiz, Yildizay

    2015-01-01

    The effect of problem-based learning (PBL) applications in an undergraduate biochemistry course on students' interest in this course was investigated through four modules during one semester. Students' views about active learning and improvement in social skills were also collected and evaluated. We conducted the study with 36 senior students from…

  13. Development and Evaluation of a Multi-Institutional Case Studies-Based Course in Food Safety

    Science.gov (United States)

    Pleitner, Aaron M.; Chapin, Travis K.; Hammons, Susan R.; Stelten, Anna Van; Nightingale, Kendra K.; Wiedmann, Martin; Johnston, Lynette M.; Oliver, Haley F.

    2015-01-01

    Developing novel, engaging courses in food safety is necessary to train professionals in this discipline. Courses that are interactive and case-based encourage development of critical thinking skills necessary for identifying and preventing foodborne disease outbreaks. The purpose of this study was to assess the efficacy of a case study…

  14. The Robotic Decathlon: Project-Based Learning Labs and Curriculum Design for an Introductory Robotics Course

    Science.gov (United States)

    Cappelleri, D. J.; Vitoroulis, N.

    2013-01-01

    This paper presents a series of novel project-based learning labs for an introductory robotics course that are developed into a semester-long Robotic Decathlon. The last three events of the Robotic Decathlon are used as three final one-week-long project tasks; these replace a previous course project that was a semester-long robotics competition.…

  15. Helping Your Local Amphibians (HYLA): An Internet-Based Amphibian Course for Educators

    Science.gov (United States)

    Murphy, Tony P.

    2001-12-01

    A pilot on-line course on amphibians was offered free to 20 educators around the United States in 1999. This course, called Helping Your Local Amphibians (HYLA), was the first of its kind on-line course for educators dealing with amphibian issues. It also used these animals as a focus to teach about the environment. The course lasted 9 weeks with some additional time for continued discussions and used various aspects of Internet technology (including a virtual conference center), media, and traditional paper-based products to complete the learning process. Five teachers were selected to attend a national amphibian summit hosted by the Center for Global Environmental Education, Hamline University, St. Paul, MN. The course was aimed primarily at upper elementary and middle school teachers, but participants included formal and nonformal educators. For the most part, educators expressed satisfaction with the course and the content, as well as the structure of the web site. For 80% of the group, this was their first Internet-based course. In addition, as part of the course, the educators were expected to take some action with their primary audiences to help local amphibian populations. This mainly took the form of surveys or habitat clean-ups. The development of the course was underwritten by grants from the National Fish and Wildlife Foundation, U.S. Fish and Wildlife Service, the Best Buy Children's Foundation, and Hamline University.

  16. A hybrid strategy in selecting diverse combinations of innovative sustainable materials for asphalt pavements

    Directory of Open Access Journals (Sweden)

    Baron Colbert

    2016-04-01

    Full Text Available This project integrates recent innovations of recycled materials used in designing and building sustainable pavements. An increasing environmental awareness and the demand for improving economic and construction efficiencies, through measures such as construction warrantees and goals to reduce air pollution under the Kyoto Protocol, have increased the efforts to implement sustainable materials in roadways. The objective of this research is to develop a systematic approach toward selecting optimum combinations of sustainable materials for the construction of asphalt pavements. The selected materials, warm mix asphalt (WMA, recycled asphalt shingles (RAS, and reclaimed asphalt pavement (RAP were incorporated in this study. The results of this research are intended to serve as guidelines in the selection of the mixed sustainable materials for asphalt pavements. The approach developed from this project draws upon previous research efforts integrating graphical modeling with optimizing the amount of sustainable materials based on the performance. With regard to moisture susceptibility and rutting potential test results, as well as the MIM analysis based on a 95% confidence interval, the rutting performance and moisture susceptibility of asphalt mixtures are not significantly different regardless of the percentages of RAS, RAP, or WMA. The optimum mixture choices could be made by the plant emission rankings with consideration of the optimal WMA types, percentages of RAS/RAP, and WMA production temperatures. The WMA mixtures prepared with 75% RAP and Advera® WMA have produced the lowest CO2 emissions among the investigated mixture types.

  17. The Development of an Inquiry-based Curriculum Specifically for the Introductory Algebra-based Physics Course

    CERN Document Server

    Thacker, B; Eligon, A M; Diaz, Abel; Eligon, Ann Marie; Thacker, Beth

    2007-01-01

    We discuss an inquiry-based curriculum that has been developed specifically for the introductory algebra-based physics course, taking into account the needs, backgrounds, learning styles and career goals of the students in that class. The course is designed to be taught in a laboratory-based environment, however parts of the materials can be used in other settings. As instructors we found ourselves drawing on materials developed for the calculus-based course and for other populations (materials developed for pre-service teachers, for example), parts of which were appropriate, but not a complete curriculum as we would like to teach it, developed specifically for students in the introductory algebra-based physics course. So we have modified and adapted parts of existing materials and integrated them with our own new units and our own format, creating a course aimed specifically at these students.

  18. The Grey-System-Based Prediction of the Service Performance of Asphalt Pavement of Expressways%基于灰色系统的高速公路沥青路面综合使用性能预测

    Institute of Scientific and Technical Information of China (English)

    范喜安

    2012-01-01

    以京沪高速公路(河北段)沥青路面使用性能评价为例进行研究。分析了影响沥青路面使用性能的主要因素。选取了2007-2011年路面使用性能各项指标数据和交通量,建立了GM(1,N)模型,预测了京沪高速公路(河北段)2012~2016年沥青路面使用性能各分项指标,误差检验表明,预测精度较高。通过预防性养护前沥青路面单项指标衰变曲线分析,得到了沥青路面综合使用性能指标,为确定预防性养护时机提供了依据。%With the performance-evaluation of the asphalt pavement of the Hebei Section of the Beiiing-Shanghai Expressway as a practical example, the main factors affecting the performance of asphalt pavement are analyzed ia the paper. With the various service performance targets and the traffic volume of the pavement built during 2007-2011 chosen, a GM (1, N) model is estab- lished to forecast all the classified targets of the service performance of the asphalt pavement of the Hebei Section of the Beijing- Shanghai Expressway. The error tests show that the accuracy of the forecast is quite high. Through the analysis of the decay curve of a single target of the asphalt pavement prior to the preventive curing, the comprehensive service performance targets of the asphalt pavement are obtained. The paper provides the basis, upon which the right time forthe preventive curing may be determined.

  19. Flow Formulation-based Model for the Curriculum-based Course Timetabling Problem

    DEFF Research Database (Denmark)

    Bagger, Niels-Christian Fink; Kristiansen, Simon; Sørensen, Matias;

    2015-01-01

    In this work we will present a new mixed integer programming formulation for the curriculum-based course timetabling problem. We show that the model contains an underlying network model by dividing the problem into two models and then connecting the two models back into one model using a maximum ow...... problem. This decreases the number of integer variables signicantly and improves the performance compared to the basic formulation. It also shows competitiveness with other approaches based on mixed integer programming from the literature and improves the currently best known lower bound on one data...

  20. Arctic-based course teaches integrated climate impact assessments

    Science.gov (United States)

    Carrying out interdisciplinary global change research is not only scientifically challenging; often, the lack of sufficiently trained young professionals presents a quite profound obstacle. Thus, there is an urgent need to train and educate young graduate students—and infuse them with enthusiasm—in the hope that they will choose a career in global change research. Current university curricula, while partly addressing such issues, still largely concentrate on disciplinary courses with a high degree of specialization. While such training is certainly important in its own right, it fails to prepare students for the more holistic approaches necessary for tackling the issues of global change.

  1. Recent Developments in Pavement Management on Irish National Roads

    OpenAIRE

    Feighan, Kieran; McGowan, Ray; Casey, Tom; O’Sullivan, Andrew

    2015-01-01

    The Irish National pavement network is Ireland’s strategic road network consisting of over 5,300 centreline kilometres of road and is managed by the National Roads Authority (NRA). There is a very significant variation across the network under a variety of headings, including pavement construction, pavement age, carriageway width, lane width, geometric design and traffic volumes carried. A large proportion of the network consists of “legacy” roads that have evolved from historic routes that a...

  2. Permeability testing of drilling core sample from pavement

    Institute of Scientific and Technical Information of China (English)

    Suda WANG; Zhengguang TANG; Xiaojun NING; Peiguan WU; Pingyi XING

    2008-01-01

    The permeability coefficient of pavement material is a very important parameter in designing the drainage of pavement structures and is also used to evalu-ate the quality of road construction. New equipment is used to measure the permeability coefficient of the pave-ment drilling core sample and relevant testing methods are introduced. Testing drilling core samples from a certain highway of Yunnan province has been proven to be feas-ible. The test results are also analyzed.

  3. Pavement Response to Variable Tyre Pressure of Heavy Vehicles

    OpenAIRE

    Arshad Ahmad Kamil; Haron Hairol Anuar; Abd Rahman Zanariah; Abdul Halim A.G.

    2016-01-01

    In recent years, the effect of overinflated tyre pressure and increased heavy vehicles’ axle load on flexible pavements has become a subject of great concern because of the higher stress levels induced and damage caused to road pavements. This paper aims to evaluate the effect of variable tyre inflation pressures (using actual tyre contact/footprint area) to determine the responses of flexible pavement. A full scale experiment was conducted on a heavy vehicle with 1:1:2 axle configuration, 10...

  4. Long-Term Field Performance of Pervious Concrete Pavement

    OpenAIRE

    Aleksandra Radlińska; Andrea Welker; Kathryn Greising; Blake Campbell; David Littlewood

    2012-01-01

    The work described in this paper provides an evaluation of an aged pervious concrete pavement in the Northeastern United States to provide a better understanding of the long-lasting effects of placement techniques as well as the long-term field performance of porous pavement, specifically in areas susceptible to freezing and thawing. Multiple samples were taken from the existing pavement and were examined in terms of porosity and unit weight, compressive and splitting tensile strength, and th...

  5. Post-graduate art therapy training in Israel: personal and professional transformation through dynamic artwork-based experiential transformative courses

    OpenAIRE

    Honig, Ofira

    2014-01-01

    Art therapy training programmes around the world feature a unique type of course based on dynamic art-work experience and conducted in the context of a core student group. The course is usually called an 'experiential group course'. There is world-wide practical recognition in the professional art therapy literature of the need for dynamic experiential artwork-based courses in art therapy training. What is new is that Israeli lecturers have extended this 'experiential group course' into what ...

  6. The Impact of an Inquiry-Based Geoscience Field Course on Pre-service Teachers

    Science.gov (United States)

    Nugent, Gwen; Toland, Michael D.; Levy, Richard; Kunz, Gina; Harwood, David; Green, Denise; Kitts, Kathy

    2012-08-01

    The purpose of this quasi-experimental study was to determine the effects of a field-based, inquiry-focused course on pre-service teachers' geoscience content knowledge, attitude toward science, confidence in teaching science, and inquiry understanding and skills. The field-based course was designed to provide students with opportunities to observe, compare, and investigate geological structures in their natural environment and to gain an understanding of inquiry via hands-on learning activities designed to immerse students in authentic scientific investigation. ANCOVA and MANCOVA analyses examining differences in outcome measures between students in the field experience ( n = 25) and education students enrolled in the traditional, classroom-based course ( n = 37) showed that students in the field course generally had significantly higher scores. Results provide evidence of the value of the field and inquiry-based approach in helping pre-service teachers develop the needed skills and knowledge to create effective inquiry-based science lessons.

  7. Environmentally friendly pavements: Results from noise measurements 2005-2008

    OpenAIRE

    Berge, Truls Svenn; Haukland, Frode; Ustad, Asbjørn

    2009-01-01

    CPX-measurements (tyre A) have been performed on a wide range of ordinary dense Norwegian road pavements and special test pavements, as part of the R&D project “Environmental friendly pavements” initiated by the Norwegian Public Roads Administration. The following conclusions can be made from the investigation:- New dense asphalt concrete pavements can give a tyre/road noise level (CPX) of 4-8 dB(A) lower noise level, compared to a chosen reference level for a pavement of type AC 0/11 and SMA...

  8. The Impact of a Participant-Based Accounting Cycle Course on Student Performance in Intermediate Financial Accounting I

    Science.gov (United States)

    Siagian, Ferdinand T.; Khan, Mohammad

    2016-01-01

    The authors investigated whether students in an Intermediate Financial Accounting I course who took a 1-credit, participant-based accounting cycle course performed better than students who did not take the accounting cycle course. Results indicate a higher likelihood of earning a better grade for students who took the accounting cycle course even…

  9. Temperature Characteristic of Asphalt Pavement Structure in Beijing Based on Temperature Survey of Test Road%北京地区沥青路面结构内部温度变化规律

    Institute of Scientific and Technical Information of China (English)

    韩丁丁; 张金喜; 魏建军

    2015-01-01

    为了掌握沥青路面温度变化规律,更加准确地指导沥青路面设计和对沥青路面病害的分析,选择北京地区某高速公路沥青路面,在路面结构内部埋设了温度测试设备,对沥青路面结构内部温度进行了跟踪监测和分析,并给出了北京地区路面结构内部温度极值的预测公式.结果表明:北京地区(实验路段中)沥青路面上面层底部全年最高温度为33.8℃,最低温度为-16.8℃.夏季沥青路面结构内部平均温度梯度为0.45℃/cm,冬季为-0.10℃/cm.路面结构内部温度降温速率在农历夏至前后最大,约0.6~1.2℃/h;路面在冬季长时间处于低温状况,降温速率在冬季较小,约0.2~0.4℃/h.北京地区1 a内沥青路面工作温度处于中低温期的时间约占85%左右.%In order to know the law of the temperature change of asphalt pavements, to design and precisely analyze the damaged asphalt pavements, temperature sensors were buried in a certain highway asphalt pavement in Beijing. And the sensors were used to track and analyze the internal temperature changes of the pavement structure. The results show that the temperature at the bottom of the upper surface varies from 33. 8 ℃ to -16. 8 ℃ during a year. The average temperature gradient of the pavement is 0. 45℃/cm in summer and -0. 10℃/cm in winter. The temperature decreasing rate of the pavement is about 0. 6~1. 2℃/h and the highest temperature decreasing rate occurs around the summer solstice of Chinese lunar calendar. The temperature decreasing rate is smaller than that of other seasons, and the record number is about 0. 2~0. 4℃/h. The working temperature of the asphalt pavement below 20℃ is about 85% within a year. A prediction formula of extreme of the internal temperature of the pavement structure was given in the paper.

  10. Discussion About Operation Environment and Design Index of Highway Subgrade Based on Subgrade and Pavement Coordination Design%与路面协调设计的公路路基设计指标及使用环境探讨

    Institute of Scientific and Technical Information of China (English)

    阮艳彬; 吴万平

    2012-01-01

    Because of the incompatible status between the current subgrade and pavement design specifications, as well as the diversity between specifications and actual highway operation environment and overloading vehicles, in the idea of subgrade and pavement coordination design, from the factors influencing subgrade structural characteristics, the effect of temperature-humidity-load on subgrade and pavement structural designing is studied. The change regularity of dynamic stress, strain and workspace depth of overload vehicles highway subgrade in different environment and load conditions is analyzed. That reveals the importance of operation environmental conditions in subgrade structural design. Last, based on the result of dynamic stress, strain analysis and the control standards, the traffic classification and design standard, as well as the design axle load criterion and subgrade intensity indexes which adapt to expressway with overloading vehicles are pointed out. Some viewpoints about highway subgrade design in operation environment based on subgrade and pavement coordination design are put forward.%针对当前公路路基路面设计协调性差及规范的适用环境与当前公路使用环境、轴载状态差异问题,本着路基路面协调设计的思想,从影响路基结构特性的因素入手,研究了温度、湿度、荷载3大影响路基路面结构设计的主要因素,分析计算了不同环境、轴载状态下重载交通公路路基动应力、应变及公路工作区深度变化规律,揭示了在使用环境条件下进行路基结构设计的重要性.最后根据路基动应力、应变分析结果与控制标准,提出了适应重载交通的交通等级与设计标准轴载,以及适应重载交通高速公路的设计轴载与路基强度指标标准建议值,并基于与路面协调设计思想对使用环境下的公路路基设计提出了一些建议.

  11. Investigating a New Way To Teach Law: A Computer-based Commercial Law Course.

    Science.gov (United States)

    Lloyd, Robert M.

    2000-01-01

    Describes the successful use of an interactive, computer-based format supplemented by online chats to provide a two-credit-hour commercial law course at the University of Tennessee College of Law. (EV)

  12. Combination of graph heuristics in producing initial solution of curriculum based course timetabling problem

    Science.gov (United States)

    Wahid, Juliana; Hussin, Naimah Mohd

    2016-08-01

    The construction of population of initial solution is a crucial task in population-based metaheuristic approach for solving curriculum-based university course timetabling problem because it can affect the convergence speed and also the quality of the final solution. This paper presents an exploration on combination of graph heuristics in construction approach in curriculum based course timetabling problem to produce a population of initial solutions. The graph heuristics were set as single and combination of two heuristics. In addition, several ways of assigning courses into room and timeslot are implemented. All settings of heuristics are then tested on the same curriculum based course timetabling problem instances and are compared with each other in terms of number of population produced. The result shows that combination of saturation degree followed by largest degree heuristic produce the highest number of population of initial solutions. The results from this study can be used in the improvement phase of algorithm that uses population of initial solutions.

  13. Un Cours de composition francaise par ordinateur (A Computer-Based Course in French Composition).

    Science.gov (United States)

    Landes, Anne; Kaplan, Alice

    1988-01-01

    The origins, organization, and methods of a Columbia University course offering computer-based instruction in French composition are outlined, and the progress of four individual students is described. (MSE)

  14. Weight Research on Pavement Performances of Asphalt Mixture Based on Comparative Matrix Method%基于比较矩阵法的沥青混合料路用性能权重研究

    Institute of Scientific and Technical Information of China (English)

    和世明

    2012-01-01

    在评价沥青混合料的路用性能这一矛盾体时,权重是一关键因素,对方案优选起重要作用。如何相对客观地确定权重是评价模型中一个非常关键的问题。通过沥青混合料各路用性能的预估寿命这一相对客观的指标,结合比较矩阵法建立了权重模型,分别求取了沥青各面层各路用性能的权重。通过分析各路用性能的权重,可进一步指导各面层的沥青混合料的设计。%In case of assessment of the contradictory pavement performances of asphalt mixture,weight is the key factor playing important role in optimization of programme.How to confirm the weight objectively is very important for assessment model.By means of a comparative objective index,the estimated life of pavement performances of asphalt mixture and in combination with comparative matrix,the weight model is established to seek the weight of pavement performances of various asphalt layers.Through the analysis of pavement performances'weight,the design of asphalt mixture for various layers can be further guided.

  15. Towards noise classification of road pavements

    OpenAIRE

    Freitas, Elisabete F.; Paulo, Joel; Coelho, J. L. Bento; Pereira, Paulo A. A.

    2008-01-01

    Noise classification of road surfaces has been addressed in many European countries. This paper presents the first approach towards noise classification of Portuguese road pavements. In this early stage, it aims at establishing guidelines for decision makers to support their noise reduction policies and the development of a classification system adapted to the European recommendations. A ranking to provide guidance on tire-road noise emission levels for immediate use by decisio...

  16. COMPARISON OF PAVEMENT STRUCTURES IN TUNNELS

    OpenAIRE

    Rimac, Ivan; Šimun, Miroslav; Dimter, Sanja

    2014-01-01

    Tunnels pose many fire risks. It is difficult to fight fires in tunnels due to their limited accessibility, the quantity of smoke, and high thermal radiation. Temperatures in tunnel fires can reach 1000 °C, and these fires can spread quickly and persist for long periods, the longest recorded in Europe lasting 53 h. The main requirements of tunnel pavement structures are driving safety and comfort, as well as low construction and maintenance costs. Choosing between using concrete or asphalt pa...

  17. Pavement Sealcoat, PAHs, and Water Quality of Urban Water Bodies: An Overview

    Science.gov (United States)

    Mahler, B. J.; Van Metre, P. C.; Ingersoll, C.; Kunz, J. L.; Kienzler, A.; Devaux, A.; Bony, S.

    2014-12-01

    Coal-tar-based (CT) sealcoat is used to protect and beautify the asphalt pavement of driveways and parking lots primarily in the central, southern, and northeastern U.S. and in Canada. CT sealcoat typically is 20 to 35 percent crude coal tar or coal-tar pitch and contains from 50,000 to 100,000 mg/kg PAHs, about 1,000 times more than asphalt-based (AS) sealcoat or asphalt itself. Tires and snowplows abrade the friable sealcoat surface into fine particles—PAH concentrations in fine particles (dust) from CT-sealcoated pavement are about 1,000 times higher than in dust from AS-sealcoated pavement (median total PAH concentrations 2,200 and 2.1 mg/kg, respectively). Use of CT sealcoat has several implications for urban streams and lakes. Source apportionment modeling has indicated that, in regions where CT sealcoat is prevalent, particles from sealcoated pavement are contributing the majority of the PAHs to recently deposited lake sediment, with implications for ecological health. Acute 2-d toxicity of runoff from CT-sealcoated pavement to stream biota, demonstrated for a cladoceran (Ceriodaphnia dubia) and fathead minnows (Pimephales promelas), continues for samples collected as long as weeks or months following sealcoat application. Using the fish-liver cell line RGL-W1, runoff collected as much as 36 days following CT-sealcoat application has been demonstrated to cause DNA damage and impair DNA repair capacity. These results demonstrate that CT runoff is a potential hazard to aquatic ecosystems for at least several weeks after sealant application, and that exposure to sunlight can enhance toxicity and genetic damage. Recent research has provided direct evidence that restricting use of CT sealcoat in a watershed can lead to a substantial reduction in PAH concentrations in receiving water bodies.

  18. Energy harvesting in pavement from passing vehicles with piezoelectric composite plate for ice melting

    Science.gov (United States)

    Faisal, Farjana; Wu, Nan; Kapoor, Kartik

    2016-04-01

    An energy harvester in the road pavement made from a piezoelectric composite plate is designed and studied to collect energy from the passing vehicles for the ice melting aim. Piezoelectric material has the ability to produce electric charge on its surface when strain takes place due to any external loading. Based on this property, a rectangular composite plate harvester is developed consisting of piezoelectric material as the energy generation coating layer and A514 steel as the substrate layer to realize the energy harvesting process from the variable pressure generated in the road pavement by passing vehicles. Based on Westergaards stress model, a numerical model is developed to calculate the three dimensional stress distribution in the pavement. Numerical simulations are conducted to study the optimization of various parameters of the harvester, such as depth of the harvester in the pavement, length and width as well as thicknesses of piezoelectric layer and the substrate. By taking in to consideration the maximum stress that can be sustained by both of the piezoelectric material and also the substrate material, an optimum design of the piezoelectric couple composite plate energy harvester is suggested. It is seen that the maximum output power, which can be generated by a single patch of 0.2m*0.2m*0.0026m dimension with a vehicle passing at 22.2 m/s, can reach up to 23.36 W. With the well-designed pavement energy harvesters, it is feasible to collect enough energy to rise the temperature of the ice with the thickness of 1cm covering a 5m width road by 20 degree Celsius within 2.5 hours. This technique can be applied to melt the ice on the roads and bridges especially in cold countries.

  19. 基于改进灰色模型的机场柔性道面性能衰减研究%On prediction model of flexible airport pavement performance degradation based on improved gray forecast model

    Institute of Scientific and Technical Information of China (English)

    刘志业

    2015-01-01

    The paper adopts the annual traffic growth ratio and soil matrix CBR,modifies the gray models,establishes the airport asphalt concrete pavement performance degradation model after the large-scale repair,and proves by the examples that the model can reflect the performance deg-radation law of the flexible pavement with high forecast accuracy and it meets the demands for the airport pavement maintenance.%采用年交通增长率和土基 CBR 两个指标,对灰色模型进行了修正,建立了大修后的机场沥青混凝土道面性能衰减模型,通过实例验证表明,该模型预测精度高,能客观反映机场柔性道面的性能衰减规律,满足机场道面养护工作的要求。

  20. Course and outcome of eating disorders in a primary care-based cohort.

    OpenAIRE

    Son, G.E. van; Hoeken, D. van; Furth, E.F. van; Donker, G A; Hoek, H.W.

    2010-01-01

    OBJECTIVE: To study the course and outcome of patients with eating disorder detected in primary care. METHOD: General practitioners (GP's) provided information on the course and outcome of eating disorders in patients (n = 147) diagnosed with anorexia nervosa (AN) or bulimia nervosa (BN) identified during a Dutch nationwide primary care-based incidence study. The research team determined the outcome based on the data provided by the GP's. The mean duration of the follow-up was 4.8 years. RESU...

  1. Teaching reading comprehension in english in a distance web-based course: new roles for teachers

    OpenAIRE

    Muñoz Marín Jorge Hugo; González Moncada Adriana

    2010-01-01

    Distance web-based learning is a popular strategy in ELT teaching in Colombia. Despite of the growth of experiences, there are very few studies regarding teachers’ participation in these courses. This paper reports preliminary findings of an on-going study aiming at exploring the roles that a teacher plays in an EFL reading comprehension distance web-based course. Data analysis suggests that teachers play new roles solving technical problems, providing immediate feedback, interacting with stu...

  2. Incorporating a Modified Problem-Based Learning Exercise in a Traditional Lecture and Lab-Based Dairy Products Course

    Science.gov (United States)

    Liceaga, Andrea M.; Ballard, Tameshia S.; Skura, Brent J.

    2011-01-01

    A modified problem-based learning (PBL) exercise was implemented in a food science Dairy Products course, which had previously been taught in the traditional lecture and laboratory format only. The first 10 wk of the course consisted of weekly lectures and laboratory exercises. During the remaining 3 wk, students were presented with a case study…

  3. Developing a Problem-Based Course Based on Needs Analysis to Enhance English Reading Ability of Thai Undergraduate Students

    Science.gov (United States)

    Bosuwon, Takwa; Woodrow, Lindy

    2009-01-01

    This paper reports on a needs analysis underlying a proposed business English reading course using a problem-based learning approach designed to enhance English reading abilities of Thai undergraduate students. As part of a work in progress, the needs analysis survey was done prior to the course design with the major stakeholders in business and…

  4. A Methodology for Assessing Skill-Based Educational Outcomes in a Pharmacy Course.

    Science.gov (United States)

    Alston, Gregory L; Griffiths, Carrie L

    2015-09-25

    Objective. To develop a methodology for assessing skill development in a course while providing objective evidence of success and actionable data to improve instructional effectiveness. Design. Course objectives were recast as skills to be demonstrated. Confidence in these skills was surveyed before and after the course. Student skills were demonstrated using 4 work products and a multiple-choice examination. Assessment. The change from precourse survey to postcourse survey was analyzed with a paired t test. Quality of the student work product was assessed using scoring guides. All students demonstrated skill mastery by scoring 70% or above on the work product, and 87/88 demonstrated individual progress on the surveyed skills during the 15-week course. Conclusion. This assessment strategy is based on sound design principles and provides robust multi-modal evidence of student achievement in skill development, which is not currently available using traditional student course evaluation surveys. PMID:27168618

  5. New structural systems for zero-maintenance pavements. Volume 2: Analysis of anchored pavements using ANSYS

    Science.gov (United States)

    Saxena, S. K.; Militsopoulos, S. G.

    1980-08-01

    A set of procedures to evaluate the response of an anchored pavement subjected to vehicle static loads, moisture variation in the subgrade, and/or temperature variation through the surface of the pavement is presented. These procedures include two computer programs known as FEMESH and ANSYS. The FEMESH program generates rectangular meshes in either a two or three dimensional coordinate system for any prespecified number and spacing of nodes. The ANSYS program evaluates the stresses, strains, and the deflections at all elements in each material included in the analytical model.

  6. Investigation of Primary Causes of Load-Related Cracking in Asphalt Concrete Pavement in North Carolina

    Science.gov (United States)

    Park, Hong Joon

    This dissertation presents causes of cracking in asphalt concrete pavement in North Carolina through field investigation and laboratory experiments with field extracted material. North Carolina is experiencing higher than anticipated rates of fatigue cracking compared to other state. These higher than expected rates could be reflective of the national trends in mix design practice or could be caused by structural pavement failures. The problems associated with premature cracking in North Carolina pavements point to the need to evaluate the North Carolina Department of Transportation (NCDOT) mixes, processes, and measures to ensure that these factors properly balance the goals of preventing cracking and minimizing permanent deformation. Without solid data from in-service pavements, any conclusions regarding the causes of these failures might be pure conjecture. Accordingly, this research examines material properties through laboratory experiments using field-extracted materials and investigates in situ pavements and pavement structure. In order to assess condition of existing pavement, alligator cracking index (ACI) was developed. The asphalt content in the top layer that exhibits top-down cracking or bottom-up cracking has a proportional relationship to ACI values. The air void content in a bottom layer that exhibits top-down cracking or bottom-up cracking shows an inverse proportional relationship to ACI values. These observations reflect reasonable results. A comparison between ACI and asphalt film thickness values does not produce noteworthy findings, but somewhat reasonable results are evident once the range of comparison is narrowed down. Thicker film thicknesses show higher ACI values. From field core visual observations, road widening is identified as a major cause of longitudinal cracking. Regions with observed layer interface separation tend to have low ACI values. Through tensile strain simulation based on actual field conditions, it is observed that

  7. Simulation of cooling effect of newly-innovated urban pavements on water and heat budgets

    Science.gov (United States)

    Nakayam, T.; Fujita, T.

    2007-12-01

    People often suffer from the intense summer heat in Japan. This trend is increasing in urban areas because of the heat island effect and global warming. The present research evaluated the effect of pavements made of traditional and new materials on water and heat budgets. We coupled the NIES Integrated Catchment-based Eco- hydrology (NICE) model (Nakayama, 2007; Nakayama and Watanabe, 2004, 2006, 2007; Nakayama et al., 2006, 2007) to an urban canopy model in order to simulate the water and heat budgets in various types of natural and artificial pavements (covered by lawn, concrete, steel plate, synthetic rubber sheet, infiltration and water-holding blocks), and to evaluate the role of a new surface material in promoting evaporation and cooling to counter the heat island phenomenon (NICE-URBAN), by comparing with the simplified empirical model. Furthermore, using the heat conductivities of natural soil, we arranged these values for artificial pavement in the model equations by including the effect of the amount of water on the heat characteristics in the material. The simulated belowground water agreed with the observed value because this model includes the processes of both interception store and soil moisture store. The NICE-URBAN simulated more correctly the cooling of water-holding pavement during the intense heat of summer in an urban area than the empirical model. Because the model estimates that the air temperature at the water-holding pavement is 2 (deg.) lower than that at the lawn and 5 (deg.) lower than that at the building rooftop, it is very powerful to use this material for positive cooling effect in combination with the lawn for passive cooling effect. The simulation of NICE-URBAN showed that the decrease of surface temperature in water-holding pavement is closely related to the promotion of evaporation from the surface, the water volume of the pavement and the surface reflectance. References; 1)Nakayama,T.,Watanabe,M.,WRR,40,doi:10.1029/2004WR003174

  8. Factors influencing a problem-based learning implementation: A case study of IT courses

    Science.gov (United States)

    Darus, Norida Muhd; Mohd, Haslina; Baharom, Fauziah; Saip, Mohamed Ali; Puteh, Nurnasran; Marzuki @ Matt, Zaharin; Husain, Mohd Zabidin; Yasin, Azman

    2016-08-01

    IT students must be trained to work efficiently as teamwork. One of the techniques that can be used to train them is through Problem-Based Learning (PBL) approach. The PBL implementation can be influenced by various factors depending on the ultimate goal of the study. This study is focusing on the IT students' perception of the PBL implementation. The student's perception is important to ensure the successfulness of the PBL implementation. Therefore, it is important to identify the factors that might influence the implementation of PBL of IT courses. This study aims to identify some catalyst factors that may influence the PBL implementation of IT courses. The study involved three (3) main phases: identifying PBL implementation factors, constructing a PBL model, and PBL model validation using statistical analysis. Four main factors are identified: PBL Characteristics, PBL Course Assessment, PBL Practices, and PBL Perception. Based on these four factors, a PBL model is constructed. Then, based on the proposed PBL model, four hypotheses are formulated and analyzed to validate the model. All hypotheses are significantly acceptable. The result shows that the PBL Characteristics and PBL Course Assessment factors are significantly influenced the PBL Practices and indirectly influenced the Students' Perception of the PBL Implementation for IT courses. This PBL model can assist decision makers in enhancing the PBL teaching and learning strategy for IT courses. It is also can be tested to other courses in the future.

  9. Patterns and Rates of Learning in Two Problem-Based Learning Courses Using Outcome Based Assessment and Elaboration Theory

    OpenAIRE

    Ted Needham; Usha Kuruganti; Pierre Zundel

    2012-01-01

    The concept of “practice makes perfect” was examined in this work in the context of effective learning. Specifically, we wanted to know how much practice was needed for students to demonstrate mastery of learning outcomes. Student learning patterns in two different university courses that use a similar education approach involving problem based learning, outcomes based assessment, and problem sequencing based on elaboration theory were examined. Learning outcomes for each course were explicit...

  10. Research on Structure Combination of Long Life Asphalt Pavement%长寿命沥青路面结构组合分析

    Institute of Scientific and Technical Information of China (English)

    高曙光; 武庆锋

    2012-01-01

    The paper advanced 3 indexes for the design of long life asphalt pavements: maximal tension strain at the bottom of asphalt pavement, maximal compression strain at the top of subgrade and rutting depth of asphalt pavements. Afterwards, it analyzed 5 long We asphalt pavement structures, including long life asphalt pavements with flexible base and long life asphalt pavements with semi-rigid base, and real parameters were used in the analysis. Finally, checking computations of the design indexes were done based on the results. The analysis indicated that, the location of maximum tension strain of long life asphalt pavements with semi-rigid base is near the top of asphalt pavement, but the location of maximum tension strain of long life asphalt pavements with flexible base is at the bottom of asphalt pavement; and the shear stress distribution is also different in the 2 kinds of pavements.%提出了寿命沥青路面的设计指标:沥青层底最大拉应变、土基顶面最大压应变及考虑路面抗剪能力的路面结构车辙深度;同时采用三维有限元方法对半刚性基层及柔性基层两种形式的长寿路面结构进行分析,分析中材料参数采用路面各结构层的实测结构模量,最后根据力学分析结果对拟定结构的设计指标进行验算.分析结果表明,半刚性基层长寿路面最大拉应变发生在沥青层硕面附近,而柔性基层路面最大拉应变出现在沥青层底面,剪应力在两种形式长寿路面中的分布形式也有很大差别.

  11. Integration of a prototype wireless communication system with micro-electromechanical temperature and humidity sensor for concrete pavement health monitoring

    Directory of Open Access Journals (Sweden)

    Shuo Yang

    2015-12-01

    Full Text Available In recent years, structural health monitoring and management (SHMM has become a popular approach and is considered essential for achieving well-performing, long-lasting, sustainable transportation infrastructure systems. Key requirements in ideal SHMM of road infrastructure include long-term, continuous, and real-time monitoring of pavement response and performance under various pavement geometry-materials-loading configurations and environmental conditions. With advancements in wireless technologies, integration of wireless communications into sensing device is considered an alternate and superior solution to existing time- and labor-intensive wired sensing systems in meeting the requirements of an ideal SHMM. This study explored the development and integration of a wireless communications sub-system into a commercial off-the-shelf micro-electromechanical sensor-based concrete pavement monitoring system. A success-rate test was performed after the wireless transmission system was buried in the concrete slab, and the test results indicated that the system was able to provide reliable communications at a distance of more than 46 m (150 feet. This will be a useful feature for highway engineers performing routine pavement scans from the pavement shoulder without the need for traffic control or road closure.

  12. Comparison Between 2-D and 3-D Stiffness Matrix Model Simulation of Sasw Inversion for Pavement Structure

    Directory of Open Access Journals (Sweden)

    Sri Atmaja P. Rosidi

    2007-01-01

    Full Text Available The Spectral Analysis of Surface Wave (SASW method is a non-destructive in situ seismic technique used to assess and evaluate the material stiffness (dynamic elastic modulus and thickness of pavement layers at low strains. These values can be used analytically to calculate load capacities in order to predict the performance of pavement system. The SASW method is based on the dispersion phenomena of Rayleigh waves in layered media. In order to get the actual shear wave velocities, 2-D and 3-D models are used in the simulation of the inversion process for best fitting between theoretical and empirical dispersion curves. The objective of this study is to simulate and compare the 2-D and 3-D model of SASW analysis in the construction of the theoretical dispersion curve for pavement structure evaluation. The result showed that the dispersion curve from the 3-D model was similar with the dispersion curve of the actual pavement profile compared to the 2-D model. The wave velocity profiles also showed that the 3-D model used in the SASW analysis is able to detect all the distinct layers of flexible pavement units.

  13. Use of leaching tests to quantify trace element release from waste to energy bottom ash amended pavements.

    Science.gov (United States)

    Roessler, Justin G; Townsend, Timothy G; Ferraro, Christopher C

    2015-12-30

    A series of roadway tests strips were paved on-site at a landfill in Florida, U.S. Waste to energy (WTE) bottom ash was used as a partial course aggregate replacement in a hot mix asphalt (HMA) and a Portland cement concrete (PCC) pavement, along with control HMA and PCC sections. This allowed for a comparison of the relative degree of leaching between both materials (HMA and PCC) as well as between the ash-amended and control pavements. Batch and monolithic tank leaching tests were conducted on the pavements. Testing of the PCC samples demonstrated that Mo and Al were elevated above regulatory thresholds for both the control and ash amended samples. Further leach testing demonstrated that the release of Mo was likely from the PCC and not a result of the inclusion of the BA into pavement. Batch leach testing of ash-amended HMA samples revealed Sb as a constituent of potential concern. The results of the monolith leaching test displayed leaching of Sb within the same order of magnitude as the regulatory threshold. Calculation of the leachability index (LI) for Sb found that it would have limited mobility when incorporated in the HMA matrix. PMID:26340550

  14. Initial experience with a calculus-based IPLS course at Vanderbilt

    Science.gov (United States)

    Hutson, M. Shane; Rericha, Erin C.

    2014-03-01

    By implementing research results from the PER community, we have designed a new calculus-based IPLS course and began teaching two sections of this course in Fall 2013, both taught by biological physicists. This course differs from Vanderbilt's other introductory physics offerings in two major ways. First, it seeks to implement PER-based active learning strategies including just-in-time teaching, peer instruction and context-rich problems. The latter are specifically designed within biomedical contexts. Second, the course content has been chosen to closely align with the core competencies delineated in the HHMI-AAMC report Scientific Foundations for Future Physicians. We provide students with a very explicit accounting (in the syllabus) of how this course will contribute to 5 of the 8 SFFP-competencies and 21 of its 37 learning objectives. Throughout the course and associated labs, we make repeated, explicit and hopefully authentic connections between physics and the life sciences. The chosen text reinforces our approach through well-developed biomedical applications of physics concepts. We will report what we've seen work and not work in our first implementation of an IPLS course and detail results regarding student learning and student attitudes towards physics.

  15. 探究公路工程路基路面压实施工技术措施%Inquiry on highway engineering subgarade pavement compaction technology measures

    Institute of Scientific and Technical Information of China (English)

    薛治国

    2015-01-01

    The thesis analyzes major factors influencing highway engineering subgrade pavement compaction,explores effective subgrade pave-ment compaction technology measures,and makes an illustration from aspects of subgrade soil-filling,pavement structure materials,base de-mands,moisture demands and compaction machines and so on,with a view to guarantee subgrade pavement stability and strength.%分析了公路工程路基路面压实的主要影响因素,探讨了进行工程路基路面压实施工技术的有效措施,并从路基填土、路面结构材料、基层要求、含水量要求、压实机具等方面作了阐述,以保证路基路面的稳定性和强度。

  16. Beyond correspondence, video conferencing, and voice mail: Internet-based master's degree courses in nursing.

    Science.gov (United States)

    Wambach, K; Boyle, D; Hagemaster, J; Teel, C; Langner, B; Fazzone, P; Connors, H; Smith, C; Forbes, S

    1999-09-01

    The changing health care system and increasing demands for primary care providers have prompted an increase in nurse practitioner programs in the United States. Nurses in rural areas that are underserved by primary care practitioners often are faced with time and distance barriers to returning to school for advanced education. This article describes Internet-based courses as a unique distance learning platform for preparing primary care nurse practitioners at the University of Kansas (KU) School of Nursing. Discussion includes course development process, matching methods to course content, and other information on promoting interaction between students and faculty. PMID:10512467

  17. Use of Shadowing-Based Learning in an Allied Health Microbiology Course

    Directory of Open Access Journals (Sweden)

    Alex A. Lowrey

    2016-05-01

    Full Text Available Students in an undergraduate microbiology course for health professions majors perform a shadowing-based learning exercise for their course project. Students accomplish this by shadowing a health care professional of their choice, specifically incorporating basic microbiological concept themes into their observations. These concept themes include the biological nature, health effects, detection, and control of microorganisms. Upon completion of the shadowing experience, students present a concise report, which is graded on how well the students connect course scientific concepts with actual clinical practice.

  18. Comparing Outcomes from Field and Classroom Based Settings for Undergraduate Geoscience Courses

    Science.gov (United States)

    Skinner, M. R.; Harris, R. A.; Flores, J.

    2011-12-01

    Field based learning can be found in nearly every course offered in Geology at Brigham Young University. For example, in our Structural Geology course field studies substitute for labs. Students collect data their own data from several different structural settings of the Wasatch Range. Our curriculum also includes a two-week, sophomore-level field course that introduces students to interpreting field relations themselves and sets the stage for much of what they learn in their upper-division courses. Our senior-level six-week field geology course includes classical field mapping with exercises in petroleum and mineral exploration, environmental geology and geological hazards. Experiments with substituting field-based general education courses for those in traditional classroom settings indicate that student cognition, course enjoyment and recruiting of majors significantly increase in a field-based course. We offer a field-based introductory geology course (Geo 102) that is taught in seven, six-hour field trips during which students travel to localities of geologic interest to investigate a variety of fundamental geological problems. We compare the outcomes of Geo 102 with a traditional classroom-based geology course (Geo 101). For the comparison both courses are taught by the same instructor, use the same text and supplementary materials and take the same exams. The results of 7 years of reporting indicate that test scores and final grades are one-half grade point higher for Geo 102 students versus those in traditional introductory courses. Student evaluations of the course are also 0.8-1.4 points higher on a scale of 1-8, and are consistently the highest in the Department and College. Other observations include increased attendance, attention and curiosity. The later two are measured by the number of students asking questions of other students as well as the instructors, and the total number of questions asked during class time in the field versus the classroom

  19. Modeling the Hydrologic Processes of a Permeable Pavement System

    Science.gov (United States)

    A permeable pavement system can capture stormwater to reduce runoff volume and flow rate, improve onsite groundwater recharge, and enhance pollutant controls within the site. A new unit process model for evaluating the hydrologic performance of a permeable pavement system has be...

  20. Exercise in Inquiry: Critical Thinking in an Inquiry-Based Exercise Physiology Laboratory Course.

    Science.gov (United States)

    DiPasquale, Dana M.; Mason, Cheryl L.; Kolkhorst, Fred W.

    2003-01-01

    Describes an inquiry-based teaching method implemented in an undergraduate exercise physiology laboratory course. Indicates students' strong, positive feelings about the inquiry-based teaching method and shows that inquiry-based learning results in a higher order of learning not typically observed in traditional style classes. This teaching method…

  1. Concentrations of polycyclic aromatic hydrocarbons (PAHs) and azaarenes in runoff from coal-tar- and asphalt-sealcoated pavement

    International Nuclear Information System (INIS)

    Coal-tar-based sealcoat, used extensively on parking lots and driveways in North America, is a potent source of PAHs. We investigated how concentrations and assemblages of PAHs and azaarenes in runoff from pavement newly sealed with coal-tar-based (CT) or asphalt-based (AS) sealcoat changed over time. Samples of simulated runoff were collected from pavement 5 h to 111 d following application of AS or CT sealcoat. Concentrations of the sum of 16 PAHs (median concentrations of 328 and 35 μg/L for CT and AS runoff, respectively) in runoff varied relatively little, but rapid decreases in concentrations of azaarenes and low molecular weight PAHs were offset by increases in high molecular weight PAHs. The results demonstrate that runoff from CT-sealcoated pavement, in particular, continues to contain elevated concentrations of PAHs long after a 24-h curing time, with implications for the fate, transport, and ecotoxicological effects of contaminants in runoff from CT-sealcoated pavement. - Highlights: • We compare PAH and azaarene concentrations in runoff from coal-tar- and asphalt-sealed pavement. • Concentrations in coal-tar-sealcoat runoff greatly exceeded those in asphalt-sealcoat runoff. • Decreases in azaarenes and LMW PAHs were offset by increases in HMW PAHs. • PAH concentrations in coal-tar-sealcoat runoff remained high for months after application. - Concentrations of PAHs in runoff from pavement with coal-tar-based sealcoat continue to be elevated for at least 3 months following sealcoat application

  2. A Learning Proposal Based on a Project and Collaborative Work: An Online Course Experience

    Directory of Open Access Journals (Sweden)

    Gabriela Cenich

    2005-11-01

    Full Text Available One of the basic necessities for education in the future is to prepare learners to participate in a computer network, since in the information society knowledge is the most critical resource for social and economic development. This paper addresses how project-based learning was designed and implemented in a course on computer science at the National University of Central Argentina. The objective of the course was to engage students in the production of projects that were authentic, meaningful, and intended for future teaching and professional use. Two types of interaction have been considered in computer-mediated learning: individual interaction (interaction with the content, and social or interpersonal interaction. This paper describes the course design, provides an overview of the processes involved in developing the project-based learning activities, and reports the responses of students to the course.

  3. A Comparison of Learning Outcomes in Skills-Based Courses: Online versus Face-to-Face Formats

    Science.gov (United States)

    Callister, Ronda Roberts; Love, Mary Sue

    2016-01-01

    In comparing the learning outcomes of online versus face-to-face courses, skills-based forms of instruction have received little attention. This study asks the question "Can skills-based courses taught online achieve the same outcomes as face-to-face courses in which the instructor and students interacting in real time may have higher levels…

  4. A Learning Proposal Based on a Project and Collaborative Work: An Online Course Experience

    OpenAIRE

    Gabriela Cenich; Graciela Santos

    2005-01-01

    One of the basic necessities for education in the future is to prepare learners to participate in a computer network, since in the information society knowledge is the most critical resource for social and economic development. This paper addresses how project-based learning was designed and implemented in a course on computer science at the National University of Central Argentina. The objective of the course was to engage students in the production of projects that were authentic, meaningfu...

  5. Creating Web-based, multimedia, and interactive courses for distance learning.

    Science.gov (United States)

    Mills, A C

    2000-01-01

    A case study describes how faculty at Saint Louis University School of Nursing have developed computer-based, multimedia courses for master's and post-master's nursing education. Lectures with slide presentations are recorded digitally and encoded for multimedia streaming over the World Wide Web for distance learning. The technology is explained in detail in terms of the specific technologies used for lecture and course development. How this technology supports graduate student learning is also presented. PMID:10835811

  6. Monitoring asphalt pavement damages using remote sensing techniques

    Science.gov (United States)

    Mettas, Christodoulos; Themistocleous, Kyriacos; Neocleous, Kyriacos; Christofe, Andreas; Pilakoutas, Kypros; Hadjimitsis, Diofantos

    2015-06-01

    One of the main issues in the maintenance plans of road agencies or governmental organizations is the early detection of damaged asphalt pavements. The development of a smart and non-destructive systematic technique for monitoring damaged asphalt pavements is considered a main priority to fill this gap. During the 1970's, remote sensing was used to map road surface distress, while during the last decade, remote sensing became more advanced, thereby assisting in the evolution of the identification and mapping of roads. Various techniques were used in order to explore condition, age, weaknesses and imperfections of asphalted pavements. These methods were fairly successful in the classification of asphalted surfaces and in the detection of some of their characteristics. This paper explores the state of the art of using remote sensing techniques for monitoring damaged pavements and some typical spectral profiles of various asphalt pavements in Cyprus area acquired using the SVC1024 field spectroradiometer.

  7. Integration of Problem-Based Learning and Web-Based Multimedia to Enhance Soil Management Course

    Science.gov (United States)

    Strivelli, R.; Krzic, M.; Crowley, C.; Dyanatkar, S.; Bomke, A.; Simard, S.; Grand, S.

    2012-04-01

    In an attempt to address declining enrolment in soil science programs and the changing learning needs of 21st century students, several universities in North America and around the world have re-organized their soil science curriculum and adopted innovative educational approaches and web-based teaching resources. At the University of British Columbia, Canada, an interdisciplinary team set out to integrate teaching approaches to address this trend. The objective of this project was to develop an interactive web-based teaching resource, which combined a face-to-face problem-based learning (PBL) case study with multimedia to illustrate the impacts of three land-uses on soil transformation and quality. The Land Use Impacts (LUI) tool (http://soilweb.landfood.ubc.ca/luitool/) was a collaborative and concentrated effort to maximize the advantages of two educational approaches: (1) the web's interactivity, flexibility, adaptability and accessibility, and (2) PBL's ability to foster an authentic learning environment, encourage group work and promote the application of core concepts. The design of the LUI case study was guided by Herrington's development principles for web-based authentic learning. The LUI tool presented students with rich multimedia (streaming videos, text, data, photographs, maps, and weblinks) and real world tasks (site assessment and soil analysis) to encourage students to utilize knowledge of soil science in collaborative problem-solving. Preliminary student feedback indicated that the LUI tool effectively conveyed case study objectives and was appealing to students. The resource is intended primarily for students enrolled in an upper level undergraduate/graduate university course titled Sustainable Soil Management but it is flexible enough to be adapted to other natural resource courses. Project planning and an interactive overview of the tool will be given during the presentation.

  8. Teaching Reform of Functional Foods Course Based on Project Learning

    OpenAIRE

    Shanhong Zhu; Dajing Fang

    2015-01-01

    This study introduces Project-based learning in functional foods Teaching, adjusting and optimizing the functional foods subjects teaching to make it more operational, practical and updating the traditional teaching methods, which is of great significance with remarkable results. And it is suitable teaching method in food science. Project-based learning refers to the teaching activities through the implementation of a complete project carried out with the aim of organically combining the theo...

  9. A project-based course about outreach in a physics curriculum

    Science.gov (United States)

    Bobroff, Julien; Bouquet, Frédéric

    2016-07-01

    We describe an undergraduate course where physics students are asked to conceive an outreach project of their own. This project-based-learning course alternates between the project conception and teaching activities about outreach. It ends in a public show. Students decide the topic and format on their own. An analysis of the students’ productions over three years shows that all physics fields were equally covered, and various formats were used (experimental devices, animation or fiction movies, games, live events, photography). Some typical examples are described. We also analyse the benefits of this approach from the students’ perspective, through a survey done over three classes. Students showed an overall very good assessment of the course (average of 4.5(0.6) on an appreciation scale from 1 to 5) and recognised having developed outreach skills but also project-management and group-work know-how. They acknowledged this course to be a unique opportunity to share with an audience their interest in physics compared to other courses. They further mentioned that it served as an intermission in a classical academic curriculum. They also point out some challenges, especially the time-consuming issue. This survey together with the practical description of the course implementation should help other universities develop similar courses.

  10. An efficient format for a problem based introductory economics course

    OpenAIRE

    Woltjer, G.B.

    2004-01-01

    Problem-based learning is rather labor intensive for teaching staff. In addition, the problem-based structure does not work always optimally in practice. Brainstorming during pre-discussion of tasks becomes very superficial, preparation of the students is far from optimal, and post-discussion is more focused on repeating what is already in the book than on the task being discussed. However, these problems can be solved.This paper discusses a number of innovations in the format of the standard...

  11. Novel work-based learning courses in analytical sciences

    OpenAIRE

    Williams, Ruth; Velasco, Maria

    2010-01-01

    The Open University (OU) is well known for the delivery of world class distance education. From 2010, the OU offers a new Foundation Degree in Analytical Sciences, developed to enhance the skills base of the workforce in analytical laboratories. It allows students to earn and learn simultaneously without taking time off. Students are sponsored by their employer and supported by an OU tutor throughout the four years of part-time study. 25 per cent of the degree comprises two work-based learni...

  12. Discussion on pavement preventive maintenance technology of asphalt pavement%沥青路面预防性养护技术探讨

    Institute of Scientific and Technical Information of China (English)

    胡逢新; 孙奕; 陈培松

    2014-01-01

    Based on analyzing the importance of preventive maintenance concept of asphalt pavement,this paper put forward the methods and steps of preventive maintenance plan selection of asphalt pavement,including preventive maintenance sections divided,preventive maintenance measures selection and preventive maintenance time determination,provided reference for preventive maintenance of asphalt pavement for high-way maintenance management department.%在分析沥青路面预防性养护理念及重要性的基础上,提出了沥青路面预防性养护方案选择的方法和步骤,包括预防性养护路段划分、预防性养护措施选择和预防性养护时机确定,为高速公路养护管理部门进行沥青路面预防性养护提供了参考。

  13. Validation of theoretical models through measured pavement response

    DEFF Research Database (Denmark)

    Ullidtz, Per

    1999-01-01

    performance. The analytical models are based on a number of simplifications with respect to reality and must be verified experimentally.Different pressure gauges were installed in a sand, assumed to be a semi-infinite halfspace. The surface of the sand was loaded by a Falling Weight Deflectometer (FWD......) at different lateral positions with respect to the gauges. An integration of the stresses measured at the plane of the gauges showed that the total load recorded by the gauges was close to the loade imposed by the FWD, cofirming the reliability of the gauges. The theoretical stress calculated using continuum...... then used to derive the elastic parameters of the pavement layeres, that would produce deflections matching the measured deflections. Stresses and strains were then calculated at the position of the gauges and compared to the measured values. It was found that all analytical models would predict the tensile...

  14. Problem effectiveness in a course using problem-based learning

    NARCIS (Netherlands)

    D.H.J.M. Dolmans (Diana); W.H. Gijselaers (Wim); H.G. Schmidt (Henk); S.B. van der Meer

    1993-01-01

    textabstractBackground. Problem-based learning (PBL) emphasizes active generation of learning issues by students. Both students and reachers, however, tend to worry that not all important knowledge will be acquired. To explore this question, problem effectiveness (i.e., for each problem, the degree

  15. Teaching Construction: A Design-Based Course Model

    Science.gov (United States)

    Love, Tyler S.; Salgado, Carlos A.

    2016-01-01

    The focus on construction in T&E education has drastically changed. This article presents a series of topics and design-based labs that can be taught at various grade levels to integrate STEM concepts while also increasing students' overall awareness of construction and structural technologies.

  16. An Evidence-based Medicine Elective Course to Improve Student Performance in Advanced Pharmacy Practice Experiences

    Science.gov (United States)

    Rudisill, Celeste N.; Bickley, A. Rebecca; McAbee, Catherine; Miller, April D.; Piro, Christina C.; Schulz, Richard

    2011-01-01

    Objective To implement and evaluate the impact of an elective evidence-based medicine (EBM) course on student performance during advanced pharmacy practice experiences (APPEs). Design A 2-hour elective course was implemented using active-learning techniques including case studies and problem-based learning, journal club simulations, and student-driven wiki pages. The small class size (15 students) encouraged independent student learning, allowing students to serve as the instructors and guest faculty members from a variety of disciplines to facilitate discussions. Assessment Pre- and posttests found that students improved on 83% of the core evidence-based medicine concepts evaluated. Fifty-four APPE preceptors were surveyed to compare the performance of students who had completed the EBM course prior to starting their APPEs with students who had not. Of the 38 (70%) who responded, the majority (86.9%) agreed that students who had completed the course had stronger skills in applying evidence-based medicine to patient care than other students. The 14 students who completed the elective also were surveyed after completing their APPEs and the 11 who responded agreed the class had improved their skills and provided confidence in using the medical literature. Conclusions The skill set acquired from this EBM course improved students' performance in APPEs. Evidence-based medicine and literature search skills should receive more emphasis in the pharmacy curriculum. PMID:21451761

  17. A Project Based CS/IS-1 Course with an Active Learning Environment

    Directory of Open Access Journals (Sweden)

    Dr. Suvineetha Herath

    2013-04-01

    Full Text Available High level programming languages use system defined data types and the user defined data types in computations. We have developed a project-based CS/IS-1 course to substitute the traditional lecture based classroom to help students design and use at least two user defined data types in their computations to solve real world problems. Abstract data types and basic programming constructs are introduced efficiently to the students in an active learning environment using games. To assess and evaluate the changes made we distributed the course module among our students and other instructors. This paper describes our experience in developing the project based active learning environment.

  18. The impact of a compulsory web-based course on preservice teachers’ motivational profile

    Directory of Open Access Journals (Sweden)

    THIERRY KARSENTI

    2007-01-01

    Full Text Available The goal of this research was to better understand the impact of the implementation of a compulsory Web-based course on preservice teacher motivation. Subjects were enrolled in a four-year teacher education program (n=429 in the province of Quebec (Canada. Our initial hypothesis was that the Web-based distance education course – designed to promote self-determination, affiliation, and a sense of competence – would positively impact the motivation of preservice teachers. Results presented are based on quantitative and qualitative data analysis. They demonstrate that a technologically rich learning environment can enhance motivation after only a few weeks.

  19. Earth System Science: Problem-based Learning Courses for Teachers Through ESSEA

    Science.gov (United States)

    Close, E.; Witiw, M. R.

    2007-12-01

    One method that has proven effective in the study of Earth system science is to use a problem-based and event- centered course organization. In such a course, different events that occur in the Earth system are examined and how each event influences subsequent events in each of Earth's spheres (the atmosphere, hydrosphere, biosphere and lithosphere) is studied. A course is composed of several problem-based modules, where each module is centered about a particular event or issue that is important to the Earth system. The Institute for Global Environmental Strategies (IGES) was recently awarded a grant by the National Science Foundation's Geo-Teach program to develop and implement courses for teachers in Earth system science. Through the Earth System Science Education Alliance (ESSEA), IGES subsequently made awards to a group of 24 universities. Under the ESSEA program, problem-based modules are being developed for courses for middle school and high school teachers. In a typical university schedule, each module is designed to last three weeks and includes both group work and individual assignments. In the first week ("Teacher as Problem Solver"), participants explore their own ideas concerning the event and exchange their ideas with other members of their group. In the second week ("Teacher as Scholar"), participants research the issue and become more familiar with the event and the sphere-to-sphere interactions that occur. In the last week ("Teacher as Designer"), each participant develops a lesson plan for his or her own classroom. Current ESSEA modules cover topics such as volcanoes, Brazilian deforestation, Antarctic ice sheets, coral reefs, and stratospheric ozone depletion. Many new modules are under development with topics that range from plate tectonics and tsunamis to agriculture and sustainable water systems. Seattle Pacific University, in cooperation with Seattle Public Schools, was recently awarded a three-year grant by IGES to provide Earth system

  20. Student Self-Efficacy in Introductory Project-Based Learning Courses

    Science.gov (United States)

    Pleiss, Geoffrey; Zastavker, Yevgeniya V.

    2012-02-01

    This study investigates first-year engineering students' self-efficacy in two introductory Project-Based Learning (PjBL) courses -- Physics (Mechanics) Laboratory and Engineering Design -- taught at a small technical institution. Twelve students participated in semi-structured open-ended interviews about their experiences in both courses. Analysis was performed using grounded theory. Results indicate that students had lower self-efficacy in Physics Lab than in Engineering Design. In Physics Lab, students reported high levels of faculty-supported scaffolding related to final project deliverables, which in turn established perceptions of an outcome-based course emphasis. Conversely, in Engineering Design, students observed high levels of scaffolding related to the intermediate project deliverables, highlighting process-centered aspects of the course. Our analyses indicate that this difference in student perceptions of course emphases -- resulting from the differences in scaffolding -- is a primary factor for the discrepancy in self-efficacy between Physics Lab and Engineering Design. Future work will examine how other variables (e.g., academic background, perception of community, gender) affect students' self-efficacy and perception of scaffolding in these PjBL courses.

  1. 柔性层状路面应力和位移场的边界元分析%Analysis of Stress and Displacement Field in Flexible Layered Pavement Based on Boundary Element Method

    Institute of Scientific and Technical Information of China (English)

    岳强; 肖洪天; 邹杰

    2009-01-01

    In order to study the stress and the displacement of the flexible multi-layer elastic pavement under various loads distributed in arbitrary shape, the boundary element method for the flexible layered pavement was presented using the fundamental solutions multi-layer solids for the analysis.With combination of the generalized Kelvin fundamental solution and the boundary element method, the boundary integral equation was established for the boundary value problem of the flexible layered pavement to explain the singular integral appearing in the kernel function.The method, which does not involve integral of layered material' s interface, can be used to solve the stress and the displacement of the multi-layer elastic media under various loads distributed in arbitrary shape.The analytical result shows that the presented method is of higher precision and can be used for analysis of the flexible pavement which mechanical parameters change along the depth because of using the generalized Kelvin fundamental solutions of layered elastic solids.%为研究任意形状分布的各种荷载作用下柔性多层弹性路面应力和位移的性状分布特点,利用层状材料的广义Kelvin基本解,建立了边界元分析方法.结合广义Kelvin基本解与边界元方法,建立柔性层状路面边值问题的边界积分方程,对于核函数中出现的奇异积分做了解答.该方程中不舍在层状材料交界面上的积分,可求解任意形状分布各种荷载作用下的多层弹性体系应力和位移.算例分析表明:该方法可以获得较高的计算精度;由于采用了层状材料的广义Kelvin基本解,该方法能处理力学参数沿深度方向任意变化的柔性路面.

  2. Pavement Pre- and Post-Treatment Performance Models Using LTPP Data

    OpenAIRE

    Lu, Pan; Tolliver, Denver

    2012-01-01

    This paper determines that pavement performance in International Roughness Index (IRI) is affected by exogenous interventions such as pavement age, precipitation level, freeze-thaw level, and lower level preservation maintenance strategies. An exponential function of pavement age was used to represent pavement IRI performance curves. Moreover, this paper demonstrates a method which calculates short-term post-pavement performance models from maintenance effect models and pre-treatment performa...

  3. Measurement of the Cooling Efficiency of Pavement-Watering as an Urban Heat Island Mitigation Technique

    Directory of Open Access Journals (Sweden)

    Martin Hendel

    2015-03-01

    Pavement watering was found to lower pavement surface temperatures by several degrees for several hours after watering, while also strongly reducing its cooling rate a few hours before and after sunset. Heat flux and storage at a depth of 5 cm in the pavement were also found to have been significantly reduced, especially during direct sunlight exposure, but also when the pavement was in the shade. Uninterrupted watering appears necessary during direct sunlight exposure of the pavement to maximize efficiency.

  4. Tire Footprint Affects Hydroplaning On Wet Pavement

    Science.gov (United States)

    Yager, Thomas J.

    1989-01-01

    Recent investigations of tire hydroplaning at highway speeds reveal, in addition to inflation pressure, tire-footprint aspect ratio (FAR), defined as width divided by length of tire surface in contact with pavement, significantly influences speed at which dynamic hydroplaning begins. Tire speeds and forces developed during tests of up to 65 mi/h (105 km/h) were monitored on flooded test surface to identify development of hydroplaning. Study focused on automotive tires because FAR's of automotive tires vary more than those of aircraft tires.

  5. Successful Implementation of Inquiry-Based Physiology Laboratories in Undergraduate Major and Nonmajor Courses

    Science.gov (United States)

    Casotti, G.; Rieser-Danner, L.; Knabb, M. T.

    2008-01-01

    Recent evidence has demonstrated that inquiry-based physiology laboratories improve students' critical- and analytical-thinking skills. We implemented inquiry-based learning into three physiology courses: Comparative Vertebrate Physiology (majors), Human Physiology (majors), and Human Anatomy and Physiology (nonmajors). The aims of our curricular…

  6. Activity Based Learning in a Freshman Global Business Course: Analyses of Preferences and Demographic Differences

    Science.gov (United States)

    Levine, Mark F.; Guy, Paul W.

    2007-01-01

    The present study investigates pre-business students' reaction to Activity Based Learning in a lower division core required course entitled Introduction to Global Business in the business curriculum at California State University Chico. The study investigates students' preference for Activity Based Learning in comparison to a more traditional…

  7. Spiral and Project-Based Learning with Peer Assessment in a Computer Science Project Management Course

    Science.gov (United States)

    Jaime, Arturo; Blanco, José Miguel; Domínguez, César; Sánchez, Ana; Heras, Jónathan; Usandizaga, Imanol

    2016-01-01

    Different learning methods such as project-based learning, spiral learning and peer assessment have been implemented in science disciplines with different outcomes. This paper presents a proposal for a project management course in the context of a computer science degree. Our proposal combines three well-known methods: project-based learning,…

  8. 重载对沥青路面车辙及疲劳寿命的影响%Influence of Heavy Load on Rutting and Fatigue Life of Asphalt Pavement

    Institute of Scientific and Technical Information of China (English)

    从志敏; 邹晓翎; 龚红仁

    2013-01-01

    为分析重载条件下沥青路面易产生车辙及疲劳病害的成因,基于弹性层状体系理论,利用ABAQUS有限元软件,分别通过车辙量和剪应力、基层疲劳模型表征路面车辙和疲劳寿命,研究了超重交通荷载对沥青路面车辙及疲劳寿命的影响.结果表明,当基层模量为0.4 GPa,轴载从100 kN增加到200 kN时,压密变形量增加了29.82%,路面内最大剪应力增加了24.7%,基层疲劳寿命缩减了95.30%;而当基层模量为2.0 GPa时,上述指标分别为27.67%,39.2%,99.26%.由此可知,重载对沥青路面结构破坏影响显著,且随着基层模量的增加,车辙和疲劳病害更加严重.研究结果有助于解释重交通路段沥青路面车辙及疲劳病害的成因.%In order to investigate the cause of the rutting and fatigue life of asphalt pavement under the heavy-load conditions, based on elastic layered system and through the finite computer ABAQUS,the relative amounts of rutting, shear stress, and base course's fatigue model were included to indicate the pavement rutting and fatigue life, respectively. The influence of heavy traffic loads on rutting and fatigue life of asphalt pavement were examined. The results show when the base modulus is 0. 4 GPa, axle load increases from 100 kN to 200 kN, the compression deformation increases about 29.82%, the maximum shear stress of asphalt pavement increases 24. 7%, the fatigue life of base course decreases 95. 30%. However, when the base modulus is 2. 0 GPa, the above indexes were 27. 67%,39. 2%,99. 26%. Thus,the influence of heavy-load on the asphalt pavement structure damage is significant,and with the increase of base course's modulus, the effect is serious. The results help to explain the causes of rutting and fatigue damage under the heavy traffic road.

  9. Ten practical, theory-based tips for clinical course planners

    DEFF Research Database (Denmark)

    Balslev, T.; Westphall, I.; Blichfeldt, S.;

    2008-01-01

    A list of practical advice and examples are given based on the literature. E-learning with cliffhanger text-cases can activate prior knowledge, and selected examination skills can be trained with simulated patients. Patient video recordings can be used to train clinical reasoning skills, including...... pattern recognition and hypothetic-deductive approaches. Interactive approaches, for example, questioning, quizzes or buzz groups imply active involvement and participation. Quizzes and MCQ-testing can provide a formative 'check-up' on learning and point to gaps in understanding for the teachers...

  10. 基于黏弹性力学分析和线性累积疲劳损伤理论的钢桥面铺装疲劳寿命预估%Fatigue Life Prediction of Steel Bridge Deck Pavement Based on Viscoelastic Mechanical Analysis and Linear Fatigue Cumulative Damage Law

    Institute of Scientific and Technical Information of China (English)

    赵国云; 闫东波; 磨炼同

    2013-01-01

    -10℃ ,0℃ and 15t: fatigue life of Stone mastic asphalt concrete(SMA) and Epoxy asphalt concret(EAC) are tested to obtain fatigue curves and equations. Dynamic mechanical tests for SMA,GAC, EAC, Eliminator waterproof adhesive layer and modified asphalt emulsion (MAE) are performed with DSR, Q800-TMA and UTM-25 hydraulic servo system to obtain viscoelastic mechanical parameters. Maximum transversal tensile strain of four kinds of deck pavement structures under load and temperature coupling influence are got by means of finite element simulation based on the project of Jiujiang Changjiang River Highway Bridge considering with local traffic and climate characteristics, Prediction of lifetime of four deck pavement structures are made according to the linear cumulative damage law. The results indicate that EAC pavement structure fatigue life is longer than GAC pavement structure,and the later structure is suited for the situation of north climate characteristics in China. Meanwhile,the application of Eliminator waterproof adhesive layer in double EAC concrete pavement structure could increase fatigue life remarkablely.%对常用于钢桥面铺装表层的SMA沥青混凝土和环氧沥青混凝土进行-10℃、0℃和15℃四点弯曲疲劳试验,得出疲劳曲线和疲劳方程;使用动态剪切流变仪(DSR)、Q800动态热机械分析仪(TMA)和UTM-25伺服液压系统对SMA沥青混凝土、浇注式沥青混凝土、环氧沥青混凝土、Eliminator防水黏结层、环氧沥青和改性乳化沥青等常用钢桥面铺装材料进行动态力学试验,获取黏弹性力学参数,并进行有限元数值模拟,得出荷载温度耦合作用下铺装表面最大横向弯拉应变.计算江西九江长江公路大桥不同温度区域下的交通量,根据线性累积疲劳损伤理论预估钢桥面铺装的使用寿命.结果表明:环氧沥青混凝土铺装结构疲劳寿命预测结果优于浇注式沥青混凝土铺装结构,后者更适合于北方

  11. Example of using small falling weight deflectomer (FWD) for Earth structures and low cost road pavement in Japan

    Science.gov (United States)

    Shibata, Hideaki; Tanaka, Yasutomo; Ono, Isamu; Okano, Tsuyoshi

    2007-01-01

    The FWD (Falling Weight Deflectometer) is an instrument which makes the weight fall freely on its loading plate to apply impact load and measures the displacement caused by the fall at the center of impact load and also at the points in radial direction from the center of impact load. A kind of instrument which is mounted on or drawn by a vehicle used for construction of concrete pavement or asphalt pavement of a runway is usually called FWD. The impact load of FWD is 49KN to 196kN and it can obtain the modulus of elasticity of each pavement layer by back analysis based on the theory of multi-layer elasticity using 6 to 8 of extemal displacement sensors. On the other hand, the small FWD is an FWD which is constructed small and easy and is applicable for hand carry. It makes the weight fall freely on the loading plate to apply impact load and measures the load and displacement caused by the fall. It was developed for mainly assessing the rigidity and bearing capacity of the subgrade easily and promptly. It can measure many points in short term and obtain coefficient of subgrade reaction and modulus of subgrade elasticity without using reaction facilities like as plate bearing test or CBR test. It has also been tried to apply the small FWD to low cost asphalt road pavement (later called as low cost road pavement). Application examples of small FWD test for earth structure and low cost load pavement in Japan are shown and the methods and test results are stated in this report.

  12. Survival Analysis of Fatigue and Rutting Failures in Asphalt Pavements

    Directory of Open Access Journals (Sweden)

    Pabitra Rajbongshi

    2016-01-01

    Full Text Available Fatigue and rutting are two primary failure mechanisms in asphalt pavements. The evaluations of fatigue and rutting performances are significantly uncertain due to large uncertainties involved with the traffic and pavement life parameters. Therefore, deterministically it is inadequate to predict when an in-service pavement would fail. Thus, the deterministic failure time which is known as design life (yr of pavement becomes random in nature. Reliability analysis of such time (t dependent random variable is the survival analysis of the structure. This paper presents the survival analysis of fatigue and rutting failures in asphalt pavement structures. It is observed that the survival of pavements with time can be obtained using the bathtub concept that contains a constant failure rate period and an increasing failure rate period. The survival function (S(t, probability density function (pdf, and probability distribution function (PDF of failure time parameter are derived using bathtub analysis. It is seen that the distribution of failure time follows three parametric Weibull distributions. This paper also works out to find the most reliable life (YrR of pavement sections corresponding to any reliability level of survivability.

  13. Student Experience and Academic Success: Comparing a Student-Centred and a Lecture-Based Course Programme

    Science.gov (United States)

    Severiens, Sabine; Meeuwisse, Marieke; Born, Marise

    2015-01-01

    Past research has shown that, under certain conditions, student-centred and small-scale course programmes result in more academic success. The present study investigates these conditions in further detail. It is examined whether, in comparison to a course programme that is relatively more lecture-based, a student-centred course programme promotes…

  14. Investigating elementary education and physical therapy majors' perceptions of an inquiry-based physics content course

    Science.gov (United States)

    Hilton, John Martin

    This study investigates why physical therapy assistant majors engage and perform better than elementary education majors in an inquiry-based conceptual physics course at Mid-Atlantic Community College. The students from each major are demographically similar, both courses are similar in depth and structure, and each course supports the students' program. However, there is an observed difference in the levels of engagement with the curriculum and performance on writing-based assessments between the two groups. To explore possible explanations for the difference, I examine students' affinity for science, their beliefs about the nature of science and scientific knowledge in the classroom, and their perception of the usefulness of science to their program. During semi-structured interviews, students from both majors displayed nearly identical weak affinities for science, epistemological beliefs, and uncertainty about the usefulness of the class. However, the physical therapy majors' ability to see the relevance of the physics course experience to their program enhanced their interest and motivation. In contrast, the elementary education students do not see connections between the course and their program, and do not see a purpose for their learning of physics content. To improve the program, I propose a two-pronged approach - designing a faded-scaffolded-inquiry approach for both classes, and developing a field-based/seminar class for the elementary education majors. The scaffolded inquiry will help both groups develop better orientations toward lab activities, and the structured observations and reflection will help the elementary group connect the material to their program.

  15. A numerical model for flexible pavements rut depth evolution with time

    OpenAIRE

    F. Allou; Chazallon, C.; HORNYCH, P

    2007-01-01

    A simplified method has been developed for the finite elements modelling of flexible pavements rut depth evolution with time. This method is based on the shakedown theory established by Zarka for metallic structures. The yield surface of Drucker-Prager and the plastic potential of Von Mises have been used. The simplified method determines straightforwardly the purely elastic state or the elastic shakedown state or the plastic shakedown state. The calibration of the simplified method with two ...

  16. Web-based training course for evaluating radiological dose assessment in NRC's license termination process.

    Science.gov (United States)

    Lepoire, D; Richmond, P; Cheng, J-J; Kamboj, S; Arnish, J; Chen, S Y; Barr, C; McKenney, C

    2008-08-01

    As part of the requirement for terminating the licenses of nuclear power plants or other nuclear facilities, license termination plans or decommissioning plans are submitted by the licensee to the U.S. Nuclear Regulatory Commission (NRC) for review and approval. Decommissioning plans generally refer to the decommissioning of nonreactor facilities, while license termination plans specifically refer to the decommissioning of nuclear reactor facilities. To provide a uniform and consistent review of dose modeling aspects of these plans and to address NRC-wide knowledge management issues, the NRC, in 2006, commissioned Argonne National Laboratory to develop a Web-based training course on reviewing radiological dose assessments for license termination. The course, which had first been developed in 2005 to target specific aspects of the review processes for license termination plans and decommissioning plans, evolved from a live classroom course into a Web-based training course in 2006. The objective of the Web-based training course is to train NRC staff members (who have various relevant job functions and are located at headquarters, regional offices, and site locations) to conduct an effective review of dose modeling in accordance with the latest NRC guidance, including NUREG-1757, Volumes 1 and 2. The exact size of the staff population who will receive the training has not yet been accurately determined but will depend on various factors such as the decommissioning activities at the NRC. This Web-based training course is designed to give NRC staff members modern, flexible access to training. To this end, the course is divided into 16 modules: 9 core modules that deal with basic topics, and 7 advanced modules that deal with complex issues or job-specific topics. The core and advanced modules are tailored to various NRC staff members with different job functions. The Web-based system uses the commercially available software Articulate, which incorporates audio, video

  17. Experience teaching CD-ROM-based course on CANDU nuclear-power-plant systems and operation

    International Nuclear Information System (INIS)

    This paper presents personal experience garnered from teaching a CD-ROM-based course on CANDU Power-Plant Systems and Operation. This course was originally developed by Prof. G.T. Bereznai as research in distance-learning techniques when he was directing the Thai-Canadian Human Resources Development Project at Chulalongkorn University in Bangkok. The course has been offered in a number of universities, including McMaster University and the University of Ontario Institute of Technology. All the course material, including lectures, assignments, and a simulator, is provided on a CD-ROM. Lectures include a spoken soundtrack covering the material. The class often includes both undergraduate and graduate students. I found that most students appreciate having the material on electronic format, which they can view and review at will and on their own time. Students find this course quite intensive - it covers all major systems in the CANDU reactor and power plant in detail. A very important component of the course is the simulator, which teaches students how systems operate in normal operation, in power manoeuvres, and during process-system malfunctions. Effort in absorbing the material and performing assignments can often exceed 10 hours per week. Some of the simulator assignments involve tricky manoeuvres, requiring several tries to achieve the expected result. Some assignments may take several hours, especially if the manoeuvres requiring repetition take 30 minutes or more in real time. I found that some instruction in the basic theory of reactor physics and systems is appreciated by students. A few possible enhancements to the simulator model were identified. Graduate students taking the course are required to do an additional project; I assigned an investigation of the effects of xenon-concentration changes during 1 week of load cycling. In summary, this course provides to students the opportunity to learn a great deal about the workings of CANDU-plant systems. (author)

  18. Using Zebrafish to Implement a Course-Based Undergraduate Research Experience to Study Teratogenesis in Two Biology Laboratory Courses.

    Science.gov (United States)

    Sarmah, Swapnalee; Chism, Grady W; Vaughan, Martin A; Muralidharan, Pooja; Marrs, Jim A; Marrs, Kathleen A

    2016-08-01

    A course-based undergraduate research experience (CURE) spanning three semesters was introduced into freshman and sophomore biology classes, with the hypothesis that participation in a CURE affects skills in research, communication, and collaboration, which may help students persist in science. Student research projects were centered on the hypothesis that nicotine and caffeine exposure during early development affects gastrulation and heart development in zebrafish. First, freshmen generated original data showing distinct effects of embryonic nicotine and caffeine exposure on zebrafish heart development and function. Next, Cell Biology laboratory students continued the CURE studies and identified novel teratogenic effects of nicotine and caffeine during gastrulation. Finally, new freshmen continued the CURE research, examining additional toxicant effects on development. Students designed new protocols, made measurements, presented results, and generated high-quality preliminary data that were studied in successive semesters. By implementing this project, the CURE extended faculty research and provided a scalable model to address national goals to involve more undergraduates in authentic scientific research. In addition, student survey results support the hypothesis that CUREs provide significant gains in student ability to (1) design experiments, (2) analyze data, and (3) make scientific presentations, translating into high student satisfaction and enhanced learning. PMID:26829498

  19. New Pedagogy for Using Internet-Based Teaching Tools in Physics Course

    CERN Document Server

    Toback, D; Novikova, I; Toback, David; Mershin, Andreas; Novikova, Irina

    2004-01-01

    Acquiring the mathematical, conceptual, and problem-solving skills required in university-level physics courses is hard work, and the average student often lacks the knowledge and study skills they need to succeed in the introductory courses. Here we propose a new pedagogical model and a straight-forwardly reproducible set of internet-based testing tools. Our work to address some of the most important student deficiencies is based on three fundamental principles: balancing skill level and challenge, providing clear goals and feedback at every stage, and allowing repetition without penalty. Our tools include an Automated Mathematics Evaluation System (AMES), a Computerized Homework Assignment Grading System (CHAGS), and a set of after-homework quizzes and mini-practice exams (QUizzes Intended to Consolidate Knowledge, or QUICK). We describe how these tools are incorporated into the course, and present some preliminary results on their effectiveness.

  20. Known Structure, Unknown Function: An Inquiry-based Undergraduate Biochemistry Laboratory Course

    CERN Document Server

    Gray, Cynthia; Lee, Christopher T; Dewald, Alison H; Cline, Matthew A; McAnany, Charles E; Columbus, Linda; Mura, Cameron

    2015-01-01

    Undergraduate biochemistry laboratory courses often do not provide students with an authentic research experience, particularly when the express purpose of the laboratory is purely instructional. However, an instructional laboratory course that is inquiry- and research-based could simultaneously impart scientific knowledge and foster a student's research expertise and confidence. We have developed a year-long undergraduate biochemistry laboratory curriculum wherein students determine, via experiment and computation, the function of a protein of known three-dimensional structure. The first half of the course is inquiry-based and modular in design; students learn general biochemical techniques while gaining preparation for research experiments in the second semester. Having learned standard biochemical methods in the first semester, students independently pursue their own (original) research projects in the second semester. This new curriculum has yielded an improvement in student performance and confidence as ...

  1. Research on Alkaline Filler Flame-Retarded Asphalt Pavement

    Institute of Scientific and Technical Information of China (English)

    HU Shuguang; ZHANG Houji; WANG Jiaolan

    2006-01-01

    Used as flame retardant of tunnel asphalt pavement, organic bromides produce a large amount of poisons and smoke in construction and flame retardation stage. The alkaline filler was found to replace mineral filler, and the flame-retarded asphalt mixtures were produced. Experimental results show that these asphalt mixtures are smoke restrained; the performances and construction technology of asphalt pavement are not influenced; also the alkaline filler is of low-price. So this kind of flame-retarded asphalt mixtures is suitable for tunnel pavement.

  2. New approach for calculating permanent deformation in asphalt pavement

    Institute of Scientific and Technical Information of China (English)

    TAN Yi-qiu; CHEN Feng-chen; LIU Hao; SU Xin; DONG Ze-jiao; DONG Yu-ming

    2010-01-01

    A new approach using the Fiber Bragg Grating(FBG)sensor and viscoelastic model to monitor and analyze the internal strain and temperature of asphalt pavement is proposed.Some parameters including peak strain,temperature and loading time were calculated with the application of multi-dimensional sensors group.These parameters were incorporated with viscoelastic model of five units to evaluate the permanent deformation of pavement.An application example was conducted,and the results show that it is feasible to analyze and calculate the permanent deformation of pavement structures with FBG sensors.

  3. SATURATED - UNSATURATED HYDRAULIC PROPERTIES OF SUBBASE COURSE MATERIAL AND SUBGRADE SOIL

    Science.gov (United States)

    Yano, Takao; Nishiyama, Satoshi; Nakashima, Shin-Ichiro; Moriishi, Kazushi; Ohnishi, Yuzo

    In order to evaluate the rainwate r storage and infiltration properties of the permeable pavement by unsaturated seepage analysis or gas-liquid two-phase flow analysis, it is important to know the unsaturated hydraulic properties of materials wh ich constitute the pavement. For this reason, we showed the unsaturated hydraulic properties of porous asphalt material s but we have not clarified the relation between the performance of the permeable pavement and the properties of all constituti on materials. In this paper, we try to determine the unsaturated hydraulic properties of subbase course and subgrade materials that greatly affect the rainwater storage and infiltration properties of the permeable pavement. We show from experiments that water retention characteristic and the un saturated hydraulic properties of subbase course and subgrade materials well match the van Genuchten model and the Irmay model.

  4. Student Response to Team-Based Learning and Mixed Gender Teams in an Undergraduate Medical Informatics Course

    OpenAIRE

    Ken Masters

    2012-01-01

    Objectives: Team-based learning (TBL) is increasingly being used in medical and medically-related courses. The aim of this study was to evaluate student responses to a TBL-based course in medical informatics at the Sultan Qaboos University, Oman. Methods: A total of 11 TBL sessions were run during a 14-week semester of the Medical Informatics II course at SQU. An online student evaluation was performed in week 13 of the course. Results: Of the 108 students on the course, 96 (88.9%) of the stu...

  5. 沥青面层的疲劳等效温度%Fatigue Equivalent Temperature for Asphalt Pavements

    Institute of Scientific and Technical Information of China (English)

    谈至明; 吁新华

    2013-01-01

    The relationship between the fatigue life of an asphalt pavement and its average temperature, temperature gradients was discussed. Based on the equivalency principal of cumulative fatigue damage, a method for calculating the fatigue equivalent temperature for asphalt pavement was put forward, with reference to the pavement temperature field data collected from 95 regions of China over the years, the corresponding fatigue equivalent temperatures were calculated and analyzed, the correlation between the standard fatigue equivalent temperature and the altitude of asphalt pavement located, the characteristic asphalt pavement temperature (pavement surface average temperature over years and its standard deviation ) were summarized. Hence, the standard fatigue equivalent temperatures for asphalt pavements in 738 regions of China were calculated, for design purpose, a contour map of the standard fatigue equivalent temperatures was initially proposed. Moreover, the influences of various factors in the non-standard conditions on the fatigue equivalent temperature for asphalt pavement were analyzed, and a set of approximate formulas were given accordingly. At last, the reliability of the calculation method and corresponding results were validated by a comparative study.%分析了沥青面层疲劳寿命与面层温度的均值和梯度的相互关系.基于疲劳损伤等效原则,给出了沥青路面面层疲劳等效温度的计算方法.根据全国95个地区多年的路面温度场数据,对沥青面层疲劳等效温度进行了计算和分析,总结了沥青面层基准疲劳等效温度与地区海拔、路表温度特征值(多年路表温度均值和标准差)之间的回归关系,据此推算得到了全国738个地区的沥青面层基准疲劳等效温度值,并绘制了可供设计采用的全国沥青面层基准疲劳等效温度等值线图,归纳了非基准条件下各因素对沥青面层疲劳等效温度的影响规律,给出了各因素修正计算

  6. Accuracy Improvement Capability of Advanced Projectile Based on Course Correction Fuze Concept

    Directory of Open Access Journals (Sweden)

    Ahmed Elsaadany

    2014-01-01

    Full Text Available Improvement in terminal accuracy is an important objective for future artillery projectiles. Generally it is often associated with range extension. Various concepts and modifications are proposed to correct the range and drift of artillery projectile like course correction fuze. The course correction fuze concepts could provide an attractive and cost-effective solution for munitions accuracy improvement. In this paper, the trajectory correction has been obtained using two kinds of course correction modules, one is devoted to range correction (drag ring brake and the second is devoted to drift correction (canard based-correction fuze. The course correction modules have been characterized by aerodynamic computations and flight dynamic investigations in order to analyze the effects on deflection of the projectile aerodynamic parameters. The simulation results show that the impact accuracy of a conventional projectile using these course correction modules can be improved. The drag ring brake is found to be highly capable for range correction. The deploying of the drag brake in early stage of trajectory results in large range correction. The correction occasion time can be predefined depending on required correction of range. On the other hand, the canard based-correction fuze is found to have a higher effect on the projectile drift by modifying its roll rate. In addition, the canard extension induces a high-frequency incidence angle as canards reciprocate at the roll motion.

  7. The Case Method: Using Case Based Instruction To Increase Ethical Understanding In Engineering Courses

    OpenAIRE

    Barry, Brock; Yadav, Aman

    2007-01-01

    The case method: Using case-based instruction to increase ethical understanding in engineering courses Introduction The paper presents a discussion of how case-based instruction is performed and the perceived benefits of its application. We begin with a brief discussion of the historical background of case- based instruction and then discuss the use of case methodologies within various educational contexts. Connections are then made to its use in general ethics instruction, as well as spec...

  8. Runoff and infiltration characteristics of pavement structures--review of an extensive monitoring program.

    Science.gov (United States)

    Illgen, M; Harting, K; Schmitt, T G; Welker, A

    2007-01-01

    The stormwater runoff and infiltration performance of permeable pavements has been systematically evaluated within an intensive monitoring program. The primary objective of the investigation was to generate a broad database, which enables the development of an advanced simulation module for urban drainage modelling. Over 160 field and lab scale experiments have been completed and analyzed for surface runoff and infiltration characteristics. The test series include several pavement types under various boundary conditions such as diverse precipitation impacts, varying surface slope and layer construction as well as different stages of surface clogging and several base and subgrade layer characteristics. The results represent a reliable and comprehensive database that allows profound conclusions and substantial recommendations. PMID:18048986

  9. A numerical model for flexible pavements rut depth evolution with time

    Science.gov (United States)

    Allou, Fatima; Chazallon, Cyrille; Hornych, Pierre

    2007-01-01

    A simplified method has been developed for the finite elements modelling of flexible pavements rut depth evolution with time. This method is based on the shakedown theory established by Zarka for metallic structures. The yield surface of Drucker-Prager and the plastic potential of Von Mises have been used. The simplified method determines straightforwardly the purely elastic state or the elastic shakedown state or the plastic shakedown state. The calibration of the simplified method with two unbound granular materials for roads under repeated loads triaxial tests, is explained. Then, a finite elements modelling of a flexible pavement has been carried out. Calculations of 2D and 3D have been performed and rut depth evolutions with time are shown, which underline the capabilities of the model to take into account the accumulation of plastic strains along the loading cycles. Copyright

  10. 三类沥青路面结构力学响应的对比分析%Comparative analysis of mechanical response of three typical asphalt pavement structures

    Institute of Scientific and Technical Information of China (English)

    申爱琴; 张艳红; 郭寅川; 台电仓; 吴超凡

    2009-01-01

    Semi-rigid asphalt pavement, flexible base asphalt pavement and composite base asphalt pavement are the main structure forms of asphalt pavement at present. The mechanical distribution characteristics are different for different pavement structure forms. Based on the reconstruction project of Beijing-Tianjing-Tangshan expressway, this paper took the Shell Designing Software BISAR 3.0 as calculation tool to get the three-dimensional response results of the three kinds of asphalt pavement, the distributions of main mechanical response variables were compared with each other using the software of Mathlab 7.0. Then a comprehensive analysis was made on the basis of the mechanical response distributions of the three structures. The results show that the every mechanical response degree of composite base asphalt pavement is between the flexible base asphalt pavement and semi-rigid asphalt pavement. The composite base asphalt pavement is in a better mechanical condition compared to flexible base asphalt pavement and semi-rigid asphalt pavement. 8 tabs,16 figs,18 refs.%针对半刚性基层、柔性基层及复合式基层沥青路面的不同力学分布特征,以京津塘高速公路改扩建工程为依托,采用壳牌设计软件BISAR 3.0为计算工具,并用Mathlab 7.0软件将三类沥青路面结构、各主要力学响应量进行三维化处理,并对力学响应分布进行了比较分析.结果表明:从路面整体受力的角度看,复合式基层沥青路面的各项力学响应均介于柔性基层沥青路面及半刚性基层沥青路面之间;复合式基层沥青路面较柔性基层沥青路面及半刚性基层沥青路面有较大的力学优势.

  11. Guidelines for Preparing High School Psychology Teachers: Course-Based and Standards-Based Approaches

    Science.gov (United States)

    American Psychologist, 2013

    2013-01-01

    Psychology is one of the most popular elective high school courses. The high school psychology course provides the foundation for students to benefit from psychological perspectives on personal and contemporary issues and learn the rules of evidence and theoretical frameworks of the discipline. The guidelines presented here constitute the second…

  12. Using Team-based Learning to teach a Large-enrollment Environmental Science Course Online

    Science.gov (United States)

    Harder, V.

    2013-12-01

    Student enrollment in many online courses is usually limited to small classes, ranging from 20-25 students. Over two summers Environmental Science 1301, with an enrollment of 50, has been piloted online using team-based learning (TBL) methods. Teams, consisting of 7 members, were assigned randomly using the group manager tool found in the learning management system. The course was organized around Learning Modules, which consisted of a quiz (individual) over the reading, a team assignment, which covered a topic from one of the chapters was completed for each learning module, and a class/group discussion. The discussion usually entailed a presentation of findings to the class by each team. This allowed teams to interact with one another and was also designed to encourage competition among the teams. Over the course of the class it was observed that as the students became comfortable with the course procedures they developed a commitment to the goals and welfare of their team. They found that as a team they could accomplish much more than an individual; they discovered strengths in their team mates that they, themselves, lacked, and they helped those team mates who struggled with the material. The teams tackled problems that would be overwhelming to an individual in the time allotted, such as running multiple scenarios with the simulations and tackling a large amount of data. Using TBL shifted the majority of responsibility of learning the material to the student with the instructor functioning as a facilitator instead of dispenser of knowledge. Dividing the class into teams made the course load manageable for the instructor while at the same time created a small-class environment for the students. In comparing this course to other, nonTBL-based online courses taught, the work load was very manageable. There were only 7-10 items to be graded per Learning Module and only 7-10 teams to monitor and provide guidance to instead of 50 individuals. Retention rates (86

  13. Web-based, virtual course units as a didactic concept for medical teaching.

    Science.gov (United States)

    Schultze-Mosgau, Stefan; Zielinski, Thomas; Lochner, Jürgen

    2004-06-01

    The objective was to develop a web-based, virtual series of lectures for evidence-based, standardized knowledge transfer independent of location and time with possibilities for interactive participation and a concluding web-based online examination. Within the framework of a research project, specific Intranet and Internet capable course modules were developed together with a concluding examination. The concept of integrating digital and analogue course units supported by sound was based on FlashCam (Nexus Concepts), Flash MX (Macromedia), HTML and JavaScript. A Web server/SGI Indigo Unix server was used as a platform by the course provider. A variety of independent formats (swf, avi, mpeg, DivX, etc.) were integrated in the individual swf modules. An online examination was developed to monitor the learning effect. The examination papers are automatically forwarded by email after completion. The results are also returned to the user automatically after they have been processed by a key program and an evaluation program. The system requirements for the user PC have deliberately been kept low (Internet Explorer 5.0, Flash-Player 6, 56 kbit/s modem, 200 MHz PC). Navigation is intuitive. Users were provided with a technical online introduction and a FAQ list. Eighty-two students of dentistry in their 3rd to 5th years of study completed a questionnaire to assess the course content and the user friendliness (SPSS V11) with grades 1 to 6 (1 = 'excellent' and 6 = 'unsatisfactory'). The course units can be viewed under the URL: http://giga.rrze.uni-erlangen.de/movies/MKG/trailer and URL: http://giga.rrze.uni-erlangen.de/movies/MKG/demo/index. Some 89% of the students gave grades 1 (excellent) and 2 (good) for accessibility independent of time and 83% for access independent of location. Grades 1 and 2 were allocated for an objectivization of the knowledge transfer by 67% of the students and for the use of video sequences for demonstrating surgical techniques by 91% of the

  14. Cost-Effective Pavement Performance Management of Indiana's Enhanced National Highway System through Strategic Modification of the Pavement Rehabilitation Treatment Trigger Values

    OpenAIRE

    Noureldin, Menna; Fricker, Jon D; Sinha, Kumares C.

    2015-01-01

    Cost-Effective Pavement Performance Management of Indiana's Enhanced National Highway System through Strategic Modification of the Pavement Rehabilitation Treatment Trigger Values Presented during Session 3: Policy and Funding, moderated by Magdy Mikhail, at the 9th International Conference on Managing Pavement Assets (ICMPA9) in Alexandria, VA. Includes conference paper and PowerPoint slides.

  15. Enhancing Student Learning in Knowledge-Based Courses: Integrating Team-Based Learning in Mass Communication Theory Classes

    Science.gov (United States)

    Han, Gang; Newell, Jay

    2014-01-01

    This study explores the adoption of the team-based learning (TBL) method in knowledge-based and theory-oriented journalism and mass communication (J&MC) courses. It first reviews the origin and concept of TBL, the relevant theories, and then introduces the TBL method and implementation, including procedures and assessments, employed in an…

  16. Relationship between Affective Learning, Instructor Attractiveness and Instructor Evaluation in Videoconference-Based Distance Education Courses

    Science.gov (United States)

    Aydin, Irem E.

    2012-01-01

    This paper is intended to reveal the results of a study in which the relationship between learners' perceptions of affective learning, instructors' attractiveness and instructor evaluations in a videoconference based distance education course was investigated. An online survey instrument was used to collect quantitative data. A series of Pearson…

  17. A Course-Based Research Experience: How Benefits Change with Increased Investment in Instructional Time

    Science.gov (United States)

    Shaffer, Christopher D.; Alvarez, Consuelo J.; Bednarski, April E.; Dunbar, David; Goodman, Anya L.; Reinke, Catherine; Rosenwald, Anne G.; Wolyniak, Michael J.; Bailey, Cheryl; Barnard, Daron; Bazinet, Christopher; Beach, Dale L.; Bedard, James E. J.; Bhalla, Satish; Braverman, John; Burg, Martin; Chandrasekaran, Vidya; Chung, Hui-Min; Clase, Kari; DeJong, Randall J.; DiAngelo, Justin R.; Du, Chunguang; Eckdahl, Todd T.; Eisler, Heather; Emerson, Julia A.; Frary, Amy; Frohlich, Donald; Gosser, Yuying; Govind, Shubha; Haberman, Adam; Hark, Amy T.; Hauser, Charles; Hoogewerf, Arlene; Hoopes, Laura L. M.; Howell, Carina E.; Johnson, Diana; Jones, Christopher J.; Kadlec, Lisa; Kaehler, Marian; Key, S. Catherine Silver; Kleinschmit, Adam; Kokan, Nighat P.; Kopp, Olga; Kuleck, Gary; Leatherman, Judith; Lopilato, Jane; MacKinnon, Christy; Martinez-Cruzado, Juan Carlos; McNeil, Gerard; Mel, Stephanie; Mistry, Hemlata; Nagengast, Alexis; Overvoorde, Paul; Paetkau, Don W.; Parrish, Susan; Peterson, Celeste N.; Preuss, Mary; Reed, Laura K.; Revie, Dennis; Robic, Srebrenka; Roecklein-Canfield, Jennifer; Rubin, Michael R.; Saville, Kenneth; Schroeder, Stephanie; Sharif, Karim; Shaw, Mary; Skuse, Gary; Smith, Christopher D.; Smith, Mary A.; Smith, Sheryl T.; Spana, Eric; Spratt, Mary; Sreenivasan, Aparna; Stamm, Joyce; Szauter, Paul; Thompson, Jeffrey S.; Wawersik, Matthew; Youngblom, James; Zhou, Leming; Mardis, Elaine R.; Buhler, Jeremy; Leung, Wilson; Lopatto, David; Elgin, Sarah C. R.

    2014-01-01

    There is widespread agreement that science, technology, engineering, and mathematics programs should provide undergraduates with research experience. Practical issues and limited resources, however, make this a challenge. We have developed a bioinformatics project that provides a course-based research experience for students at a diverse group of…

  18. A Combination Course and Lab-Based Approach to Teaching Research Skills to Undergraduates

    Science.gov (United States)

    Danowitz, Amy M.; Brown, Ronald C.; Jones, Clinton D.; Diegelman-Parente, Amy; Taylor, Christopher E.

    2016-01-01

    Undergraduate research is an important capstone experience that provides students with the conceptual and technical aptitude for graduate or industrial research. However, this experience is often compressed into a single term in a course-based undergraduate research experience (CURE) or run by individual faculty members for select students on an…

  19. Promoting Problem-Based Learning in Retailing and Services Marketing Course Curricula with Reality Television

    Science.gov (United States)

    Rosenbaum, Mark S.; Otalora, Mauricio Losada; Ramírez, Germán Contreras

    2015-01-01

    This research provides business educators who teach retailing and services courses with an innovative way to encourage students to engage in problem-based learning solving by incorporating reality television into their curricula. The authors explore the reality television genre from several theoretical perspectives to lend support to the…

  20. A Course-Based Undergraduate Research Experience Investigating p300 Bromodomain Mutations

    Science.gov (United States)

    Shanle, Erin K.; Tsun, Ian K.; Strahl, Brian D.

    2016-01-01

    Course-based undergraduate research experiences (CUREs) provide an opportunity for students to engage in experiments with outcomes that are unknown to both the instructor and students. These experiences allow students and instructors to collaboratively bridge the research laboratory and classroom, and provide research experiences for a large…

  1. Application of ICT-based Learning Resources for University Inorganic Chemistry Course Training

    Directory of Open Access Journals (Sweden)

    Tatyana M. Derkach

    2013-01-01

    Full Text Available The article studies expediency and efficiency of various ICT-based learning resources use in university inorganic chemistry course training, detects difference of attitudes toward electronic resources between students and faculty members, which create the background for their efficiency loss

  2. Competence based learning for an on-line course on flood modelling for management

    NARCIS (Netherlands)

    Popescu, Ioanna; Jonoski, Andreja; Keuls, Carel

    2009-01-01

    Popescu, I., Jonoski, A., & Keuls, C. (2009). Competence based learning for an on-line course on flood modelling for management. Proceedings of the 33rd International Association of Hydraulic Engineering & Research (IAHR Congress). August, 9-14, 2009, Vancouver, Canada: TENCompetence.

  3. Competency-Based Instruction for the Modern Office/Word Processing Technology Course. Final Report.

    Science.gov (United States)

    LeVan, Jan

    This report describes and provides materials developed by a project to set up competency-based instruction for designated competency levels in the Modern Office/Word Processing Technology Course in an area vocational school. Following an abstract and a report that details conclusions and recommendations, materials developed by the project are…

  4. Digital Photography and Web-Based Assignments in an Urban Field Course: Snapshots from Berlin

    Science.gov (United States)

    Latham, Alan; McCormack, Derek P.

    2007-01-01

    This paper reflects on the use of digital photography in urban-based human geography fieldwork. It draws on the authors' experience of introducing digital photography into the teaching and assessment of a level 3 undergraduate field course in Berlin. To begin they outline how they sought to use simple digital technologies in order to facilitate…

  5. Success factors of social innovations by a community-based learning course (CBLC)

    NARCIS (Netherlands)

    Wink, G.; Casimir, G.; Goris, M.

    2014-01-01

    This is the success story of a community-based learning course (CBLC) project addressing the concerns of the international community of students and staff of Wageningen University and Research Centre (WageningenUR). A joint effort of this community, WageningenUR and social entrepreneurs resulted in

  6. The MORPG-Based Learning System for Multiple Courses: A Case Study on Computer Science Curriculum

    Science.gov (United States)

    Liu, Kuo-Yu

    2015-01-01

    This study aimed at developing a Multiplayer Online Role Playing Game-based (MORPG) Learning system which enabled instructors to construct a game scenario and manage sharable and reusable learning content for multiple courses. It used the curriculum of "Introduction to Computer Science" as a study case to assess students' learning…

  7. The Effect of Teaching Strategy Based on Multiple Intelligences on Students' Academic Achievement in Science Course

    Science.gov (United States)

    Abdi, Ali; Laei, Susan; Ahmadyan, Hamze

    2013-01-01

    The purpose of this study was to investigate the effects of Teaching Strategy based on Multiple Intelligences on students' academic achievement in sciences course. Totally 40 students from two different classes (Experimental N = 20 and Control N = 20) participated in the study. They were in the fifth grade of elementary school and were selected…

  8. Food and Culture: A Pedagogical Approach to Contextualizing Food-Based Activities in Multicultural Counseling Courses

    Science.gov (United States)

    Sommer, Carol A.; Rush, Lee Covington; Ingene, Daphne H.

    2011-01-01

    Pedagogic approaches that draw on reflective practices and experiential activities are valued for their perceived ability to enhance multicultural understanding. The use of food-based assignments is not uncommon in multicultural counseling courses; however, the authors contend that although these activities may be experiential in nature, they are…

  9. Using a Critical Appraisal Assignment to Infuse Evidence-Based Practice into a Therapeutic Modality Course

    Science.gov (United States)

    Zwart, Mary Beth; Olson, Bernadette

    2014-01-01

    Context: It is the responsibility of athletic training educators, through curriculum and clinical experiences, to engage students towards adopting evidence-based practice (EBP) into their practice. The initial task of implementing EBP into a curriculum or course can seem like a large task for educators and students. As a way to start scaffolding…

  10. A Game-Based Approach to an Entire Physical Chemistry Course

    Science.gov (United States)

    Daubenfeld, Thorsten; Zenker, Dietmar

    2015-01-01

    We designed, implemented, and evaluated a game-based learning approach to increase student motivation and achievement for an undergraduate physical chemistry course. By focusing only on the most important game aspects, the implementation was realized with a production ratio of 1:8 (study load in hours divided by production effort in hours).…

  11. Effectiveness of inquiry-based learning in an undergraduate exercise physiology course

    DEFF Research Database (Denmark)

    Nybo, Lars; May, Michael

    2015-01-01

    The present study was conducted to investigate the effects of changing a laboratory physiology course for undergraduate students from a traditional step-by-step guided structure to an inquiry-based approach. With this aim in mind, quantitative and qualitative evaluations of learning outcomes...

  12. Policy Enacted--Teachers' Approaches to an Outcome-Based Framework for Course Design

    Science.gov (United States)

    Barman, Linda; Bolander-Laksov, Klara; Silén, Charlotte

    2014-01-01

    In this paper, we report on how teachers in Higher Education enact policy. Outcome-based education (OBE) serves as an example of a governmental educational policy introduced with the European Bologna reform. With a hermeneutic approach, we have studied how 14 teachers interpreted this policy and re-designed their courses. The findings show…

  13. Measuring Language-Related Outcomes of Community-Based Learning in Intermediate Spanish Courses

    Science.gov (United States)

    Pellettieri, Jill

    2011-01-01

    This pilot study investigates whether requiring participation in community-based learning can motivate intermediate level Spanish learners to engage in more frequent interaction in Spanish outside of the classroom and course requirements. Using the theoretical framework of willingness to communicate in a second language, this study combines both…

  14. A Modified Approach to Team-Based Learning in Linear Algebra Courses

    Science.gov (United States)

    Nanes, Kalman M.

    2014-01-01

    This paper documents the author's adaptation of team-based learning (TBL), an active learning pedagogy developed by Larry Michaelsen and others, in the linear algebra classroom. The paper discusses the standard components of TBL and the necessary changes to those components for the needs of the course in question. There is also an empirically…

  15. Numerical Problems and Agent-Based Models for a Mass Transfer Course

    Science.gov (United States)

    Murthi, Manohar; Shea, Lonnie D.; Snurr, Randall Q.

    2009-01-01

    Problems requiring numerical solutions of differential equations or the use of agent-based modeling are presented for use in a course on mass transfer. These problems were solved using the popular technical computing language MATLABTM. Students were introduced to MATLAB via a problem with an analytical solution. A more complex problem to which no…

  16. Students' Perception of Interdisciplinary, Problem-Based Learning in a Food Biotechnology Course

    Science.gov (United States)

    Ng, Betsy L. L.; Yap, Kueh C.; Hoh, Yin K.

    2011-01-01

    Abstract: Students' perception of 8 criteria (rationale of the problem; interdisciplinary learning; facilitator asked essential questions; learner's skills; assessments; facilitation procedures; team's use of resources [team collaboration], and facilitator within a problem-based learning context) were assessed for a food biotechnology course that…

  17. Activity-Based Costing Models for Alternative Modes of Delivering On-Line Courses

    Science.gov (United States)

    Garbett, Chris

    2011-01-01

    In recent years there has been growth in online distance learning courses. This has been prompted by; new technology such as the Internet, mobile learning, video and audio conferencing: the explosion in student numbers in Higher Education, and the need for outreach to a world wide market. Web-based distance learning is seen as a solution to…

  18. Exploring the Benefits of Community-Based Research in a Sociology of Sexualities Course

    Science.gov (United States)

    Bach, Rebecca; Weinzimmer, Julianne

    2011-01-01

    The benefits of community-based research (CBR) in the sociology classroom go beyond those associated with traditional service learning. Here, students use their sociological skills to examine and propose solutions to local social problems addressed by community organizations. Through analyzing students' course reflection journals and the results…

  19. Mixing Problem Based Learning and Conventional Teaching Methods in an Analog Electronics Course

    Science.gov (United States)

    Podges, J. M.; Kommers, P. A. M.; Winnips, K.; van Joolingen, W. R.

    2014-01-01

    This study, undertaken at the Walter Sisulu University of Technology (WSU) in South Africa, describes how problem-based learning (PBL) affects the first year 'analog electronics course', when PBL and the lecturing mode is compared. Problems were designed to match real-life situations. Data between the experimental group and the control group that…

  20. A Competence-Based Course Authoring Concept for Learning Platforms with Legacy Assignment Tools

    NARCIS (Netherlands)

    Then, Matthias; Wallenborn, Benjamin; Ianniello, Birgit; Vu, Duc; Swoboda, Tobias; Fuchs, Michael; Hemmje, Matthias

    2016-01-01

    This paper is concerned with several of the most important aspects of Competence-Based Learning (CBL): course authoring, assignments, and categorization of learning content. The latter is part of the so-called Bologna Process (BP) and can effectively be supported by integrating knowledge resources l