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. Structural Improvements of Flexible Pavements Using Geosynthetics for Base Course Reinforcement

    Science.gov (United States)

    2009-10-01

    Engineering Laboratory 72 Lyme Road Hanover, NH 03755-1290 Final report Approved for public release; distribution is unlimited. Prepared for Federal...these cases.) Empirical rutting models presented in NCHRP 1-37A, Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures...Mechanistic- Empirical Design of New and Rehabilitated Pavement Structures (http://www.trb.org/mepdg/). The research effort included the development of

  3. Comparative Study of Asphalt Layer Temperature Field of Combined Type Pavement and Asphalt Pavement with Semi -Rigid Base Course%复合式路面与半刚性基层沥青路面的沥青层温度场对比研究

    Institute of Scientific and Technical Information of China (English)

    王锐

    2012-01-01

    The comparative Study of asphalt layer temperature field of combined type pavement and asphalt pavement with semi -rigid base course could provide support for design and construction of asphalt layer of com- bined type pavement or "change white to black" pavement (paving asphalt surface on old cement concrete pave- ment). Taking the asphalt layer as 2 -3 layers with not totally same thickness and material, each layer is studied and analyzed one after one. The result shows that the temperature field of asphalt layer of the two pavement struc- ture is very similar and the design and construction of asphalt layer of combined type pavement affected by tempera- ture could take that of asphalt pavement with semi - rigid base course as a reference.%通过对复合式路面与半刚性基层沥青路面的沥青层温度场对比研究,可为复合式路面或"白改黑"路面(旧水泥混凝土路面加铺沥青面层)沥青层的设计及施工提供技术支持。将沥青层看作是厚度和材料不全相同的2~3层,然后逐层研究分析,结果表明两种路面结构沥青层的温度场非常相似,认为温度作用下复合式路面沥青层的设计及施工经验可借鉴半刚性基层沥青路面。

  4. Open-Graded Bases for Airfield Pavements.

    Science.gov (United States)

    1987-07-01

    pressure. 7. The rapid drainage of the bases is particularly important for rigid pavement to prevent pumping at the joints. Cedergren (1974) was a particu...filter cloth, collector trenches or perforated collector pipe, pipe outlets, and outlet markers. 11. From the studies by Cedergren , Rollings, and...paper No. 2516, American Society of Civil Engineers, New York. Cedergren , H. R. 1974a. Drainage of Highway and Airfield Pavements, John Wiley and Sons

  5. 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.

  6. 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.

  7. A novel micromechanics based approach in modeling pavement response

    Science.gov (United States)

    Bhattacharya, Arun

    For maintaining a smooth flow of traffic in the nation's highway system, sections of pavements that are damaged need to be serviced frequently. Among the various types of damage, those caused by heavy trucks are a major concern. Based on a detailed and broad literature survey, it is apparent that no analytical model exists which could closely predict dynamic pavement response and progressive damage, even qualitatively, due to truck loading. It is such a model that is developed in this work. In order to predict pavement response and damage analytically, a model will have to be based on a theory that captures the essential features of the pavement material. The state-of-the-art Microplane Theory, which has never been applied before to pavement, is chosen to model the material behavior in this research. The theory is implemented in a finite element code to predict tri-axial pavement response. The pavement material damage due to traffic loading is also presented qualitatively. Furthermore, using Taguchi Methods, the critical parameters in a pavement design are determined. Finally, the response of pavement to various joint designs parameters is evaluated.

  8. WILLIAMS ELEMENT FOR REFLECTIVE CRACK PROPAGATION IN ASPHALT PAVEMENT ON SEMI-RIGID BASE COURSE%半刚性基层沥青路面反射裂缝扩展过程分析的Williams单元

    Institute of Scientific and Technical Information of China (English)

    徐华; 杨绿峰; 佘振平

    2013-01-01

    This paper presented a Williams element with generalized degrees of freedom (GDOFs) for stress intensity factor (SIF) analysis of reflective crack in asphalt pavement on semi-rigid base course by means of the layered linear elastic plane strain model and isoparametric element.The stiffness equation was developed for Williams element with GDOFs to yield directly the SIF at the reflective crack tip in the asphalt pavement,as the Williams element contains parameters related to the SIF.The SIF variation is investigated during the propagation of reflective cracking under symmetrical and partial load respectively.The influence of the material and geometrical parameters on the SIF was discussed in details.Numerical example shows that the Williams element has the advantage of simplicity as well as high accuracy.Results from the Williams element agree well with those by the traditional quarter-point element,therefore Williams element can be used for SIF evaluation at the reflective crack tip in the asphalt pavement on the semi-rigid base course.%该文对半刚性基层沥青路面结构采用弹性层状体系平面应变分析模型,利用改进的Williams级数,结合广义参数有限元法和常规等参元,建立了反射裂缝裂尖应力强度因子分析的广义参数Williams单元,并推导了Williams单元的刚度方程,据此研究了正对称荷载和偏载分别作用时,反射裂缝扩展过程中应力强度因子的变化规律;重点分析了偏载作用下路面结构层参数与应力强度因子之间的关系.Williams单元中含有与应力强度因子相关的参数,可以直接获得裂尖应力强度因子.算例分析表明:Williams单元与传统方法的计算结果吻合较好,且格式简单,计算精度高,适用于沥青路面反射裂缝扩展过程分析.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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 ...

  14. Effects of rejuvenator seal and fog seal on performance of open-graded friction course pavement

    Directory of Open Access Journals (Sweden)

    Nadeem A. Qureshi

    2013-05-01

    Full Text Available An open-graded friction course (OGFC is a special-purpose surface layer of hot-mix asphalt (HMA pavement that is increasingly being used around the world. Owing to its numerous benefits, OGFC is being regularly used as a final riding surface on interstate and high-traffic expressways by different highway agencies in the United States. However, some OGFC sections have experienced premature failure due to ravelling only after 6-8 years of service life. To maintain an effective, longer service life and enhanced performance of OGFC, preventive maintenance has been considered essential. There are several approaches to maintaining OGFC, one of which is the application of a fog seal and rejuvenator seal. A fog seal can reduce ravelling and extend the service life of OGFC while a rejuvenator seal can revitalise the existing aged asphalt binder in the top OGFC layer. This research focuses on optimising the fog and rejuvenator seal application rates by evaluating their effectiveness in terms of surface friction and durability. Three types of seal material were evaluated: Pavegaard (PG and Pavepreserve (PP asphalt rejuvenators and a cationic slow-setting asphalt emulsion (CSS-1H as a fog seal. Improvement in abrasion resistance of OGFC pavement was observed on application of fog and rejuvenator seals but surface friction was reduced to some extent. Hamburg test clearly shows a trend that the medium application rate of 0.10 gallon/square yard is better in enhancing resistance to rutting/moisture susceptibility of OGFC.

  15. 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.

  16. 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.

  17. Rutting Prediction in Asphalt Pavement Based on Viscoelastic Theory

    Directory of Open Access Journals (Sweden)

    Nahi Mohammed Hadi

    2016-01-01

    Full Text Available Rutting is one of the most disturbing failures on the asphalt roads due to the interrupting it is caused to the drivers. Predicting of asphalt pavement rutting is essential tool leads to better asphalt mixture design. This work describes a method of predicting the behaviour of various asphalt pavement mixes and linking these to an accelerated performance testing. The objective of this study is to develop a finite element model based on viscoplastic theory for simulating the laboratory testing of asphalt mixes in Hamburg Wheel Rut Tester (HWRT for rutting. The creep parameters C1, C2 and C3 are developed from the triaxial repeated load creep test at 50°C and at a frequency of 1 Hz and the modulus of elasticity and Poisson’ s ratio determined at the same temperature. Viscoelastic model (creep model is adopted using a FE simulator (ANSYS in order to calculate the rutting for various mixes under a uniform loading pressure of 500 kPa. An eight-node with a three Degrees of Freedom (UX, UY, and UZ Element is used for the simulation. The creep model developed for HWRT tester was verified by comparing the predicted rut depths with the measured one and by comparing the rut depth with ABAQUS result from literature. Reasonable agreement can be obtained between the predicted rut depths and the measured one. Moreover, it is found that creep model parameter C1 and C3 have a strong relationship with rutting. It was clear that the parameter C1 strongly influences rutting than the parameter C3. Finally, it can be concluded that creep model based on finite element method can be used as an effective tool to analyse rutting of asphalt pavements.

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

    OpenAIRE

    Aderinola, O.S

    2016-01-01

    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 s...

  19. 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.

  20. 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...

  1. 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.

  2. 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.

  3. 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.

  4. PHYSIOLOGICAL INFORMATION FOR PAVEMENT HEALTH MONITORING BASED ON SURFACE RIDE QUALITY

    Science.gov (United States)

    Tomiyama, Kazuya; Kawamura, Akira; Takahashi, Kiyoshi; Ishida, Tateki

    Pavement ride quality testing has traditionally been based on subjective questionnaire ratings. The questionnaire survey has ability to directly measure the sense of road users' ride quality. However, it is difficult to quantify the evaluation results based on the questionnaire due to its lack of objectivity. This study examines pavement health monitoring method using physiological information such as heart rate variability (HRV) for detecting mental stress of road users toward pavement ride quality. First, a results of a driving simulator experiment shows that potential mental stress caused by road roughness can be observed in high-frequency oscillations in 0.15-0.4Hz of HRV processed by continuous wavelet transform. Then, the high-frequency oscillations of HRV is summarized as an index related to the mental stress that makes objective ride quality evaluation possible. Finally, this study indicates that the index contributes to improve the accuracy of pavement health monitoring based on surface ride quality.

  5. 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.

  6. Use of Reclaimed Asphalt Pavement in Conjunction with Ground Improvement: A Case History

    OpenAIRE

    Foye, Kevin C.

    2011-01-01

    The use of Reclaimed Asphalt Pavement (RAP) in lieu of virgin crushed stone aggregate is becoming a widely accepted practice for a number of construction applications, particularly pavement base courses. A number of laboratory RAP studies have considered the mechanical properties of RAP bases in order to support pavement designs incorporating RAP. These studies have revealed a number of interesting relationships between RAP moisture content, compaction, and stiffness. This paper discusses the...

  7. Approaches for a 3D assessment of pavement evenness data based on 3D vehicle models

    Directory of Open Access Journals (Sweden)

    Andreas Ueckermann

    2015-04-01

    Full Text Available Pavements are 3D in their shape. They can be captured in three dimensions by modern road mapping equipment which allows for the assessment of pavement evenness in a more holistic way as opposed to current practice which divides into longitudinal and transversal evenness. It makes sense to use 3D vehicle models to simulate the effects of 3D surface data on certain functional criteria like pavement loading, cargo loading and driving comfort. In order to evaluate the three criteria mentioned two vehicle models have been created: a passenger car used to assess driving comfort and a truck-semitrailer submodel used to assess pavement and cargo loading. The vehicle models and their application to 3D surface data are presented. The results are well in line with existing single-track (planar models. Their advantage over existing 1D/2D models is demonstrated by the example of driving comfort evaluation. Existing “geometric” limit values for the assessment of longitudinal evenness in terms of the power spectral density could be used to establish corresponding limit values for the dynamic response, i.e. driving comfort, pavement loading and cargo loading. The limit values are well in line with existing limit values based on planar vehicle models. They can be used as guidelines for the proposal of future limit values. The investigations show that the use of 3D vehicle models is an appropriate and meaningful way of assessing 3D evenness data gathered by modern road mapping systems.

  8. 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.

  9. COMPARATIVE EVALUATION OF PAVEMENT CRACK DETECTION USING KERNEL-BASED TECHNIQUES IN ASPHALT ROAD SURFACES

    Directory of Open Access Journals (Sweden)

    A. Miraliakbari

    2016-06-01

    Full Text Available 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.

  10. 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.

  11. 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.

    2016-11-01

    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.

  12. Coal-tar-based pavement sealcoat, polycyclic aromatic Hydrocarbons (PAHs), and environmental health

    Science.gov (United States)

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

    2011-01-01

    Studies by the U.S. Geological Survey (USGS) have identified coal-tar-based sealcoat-the black, viscous liquid sprayed or painted on asphalt pavement such as parking lots-as a major source of polycyclic aromatic hydrocarbon (PAH) contamination in urban areas for large parts of the Nation. Several PAHs are suspected human carcinogens and are toxic to aquatic life.

  13. Wavelet-based pavement image compression and noise reduction

    Science.gov (United States)

    Zhou, Jian; Huang, Peisen S.; Chiang, Fu-Pen

    2005-08-01

    For any automated distress inspection system, typically a huge number of pavement images are collected. Use of an appropriate image compression algorithm can save disk space, reduce the saving time, increase the inspection distance, and increase the processing speed. In this research, a modified EZW (Embedded Zero-tree Wavelet) coding method, which is an improved version of the widely used EZW coding method, is proposed. This method, unlike the two-pass approach used in the original EZW method, uses only one pass to encode both the coordinates and magnitudes of wavelet coefficients. An adaptive arithmetic encoding method is also implemented to encode four symbols assigned by the modified EZW into binary bits. By applying a thresholding technique to terminate the coding process, the modified EZW coding method can compress the image and reduce noise simultaneously. The new method is much simpler and faster. Experimental results also show that the compression ratio was increased one and one-half times compared to the EZW coding method. The compressed and de-noised data can be used to reconstruct wavelet coefficients for off-line pavement image processing such as distress classification and quantification.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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 %.

  19. Experimental study of the effect of the thermal conductivity of EAF slag aggregates used in asphaltic concrete of wearing courses on the durability of road pavements

    OpenAIRE

    Barra Bizinotto, Marilda; Aponte Hernández, Diego Fernando; Vázquez Ramonich, Enric; Méndez Candelario, Braulio Aquilino; Miró Recasens, José Rodrigo; Valls del Barrio, Susanna

    2017-01-01

    Electric Arc Furnace (EAF) steel slag is the basic material used to obtain good quality aggregates in different layers of road pavements. Many scientific papers have reported on the high frictional and abrasion resistance of this material. EAF slag aggregates are hard, dense, chemically stable and have good adhesion with bitumen, all characteristics related with its high alkaline character. These properties are important in hot mix asphalt for wearing courses where high wear is present and op...

  20. 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.

  1. 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

    heavy traffic and severe weather conditions in Greenland. Based on the initial set of strain data collected under the slow-moving loader right after construction, the highest strain value was observed from the test section with the highest amount of SBS-based compound. The increased amount of SBS......-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...... weather....

  2. Simplified Pavement Design for LPAs: Introduction to PaveXpress

    OpenAIRE

    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...

  3. 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.

  4. Condition assessment of concrete pavements using both ground penetrating radar and stress-wave based techniques

    Science.gov (United States)

    Li, Mengxing; Anderson, Neil; Sneed, Lesley; Torgashov, Evgeniy

    2016-12-01

    Two stress-wave based techniques, ultrasonic surface wave (USW) and impact echo (IE), as well as ground penetrating radar (GPR) were used to assess the condition of a segment of concrete pavement that includes a layer of concrete, a granular base and their interface. Core specimens retrieved at multiple locations were used to confirm the accuracy and reliability of each non-destructive testing (NDT) result. Results from this study demonstrate that the GPR method is accurate for estimating the pavement thickness and locating separations (air voids) between the concrete and granular base layers. The USW method is a rapid way to estimate the in-situ elastic modulus (dynamic elastic modulus) of the concrete, however, the existence of air voids at the interface could potentially affect the accuracy and reliability of the USW test results. The estimation of the dynamic modulus and the P-wave velocity of concrete was improved when a shorter wavelength range (3 in. to 8.5 in.) corresponding to the concrete layer thickness was applied instead of the full wavelength rage (3 in. to 11 in.) based on the standard spacing of the receiver transducers. The IE method is proved to be fairly accurate in estimating the thickness of concrete pavements. However, the flexural mode vibration could affect the accuracy and reliability of the test results. Furthermore, the existence of air voids between the concrete and granular base layers could affect the estimation of the compression wave velocity of concrete when the full wavelength range was applied (3 in. to 11 in.). Future work is needed in order to improve the accuracy and reliability of both USW and IE test results.

  5. 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.

  6. 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.

  7. 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.

  8. Recycled asphalt pavement - fly ash geopolymers as a sustainable pavement base material: Strength and toxic leaching investigations.

    Science.gov (United States)

    Hoy, Menglim; Horpibulsuk, Suksun; Rachan, Runglawan; Chinkulkijniwat, Avirut; Arulrajah, Arul

    2016-12-15

    In this research, a low-carbon stabilization method was studied using Recycled Asphalt Pavement (RAP) and Fly Ash (FA) geopolymers as a sustainable pavement material. The liquid alkaline activator (L) is a mixture of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH), and high calcium FA is used as a precursor to synthesize the FA-RAP geopolymers. Unconfined Compressive Strength (UCS) of RAP-FA blend and RAP-FA geopolymer are investigated and compared with the requirement of the national road authorities of Thailand. The leachability of the heavy metals is measured by Toxicity Characteristic Leaching Procedure (TCLP) and compared with international standards. The Scanning Electron Microscopy (SEM) analysis of RAP-FA blend indicates the Calcium Aluminate (Silicate) Hydrate (C-A-S-H) formation, which is due to a reaction between the high calcium in RAP and high silica and alumina in FA. The low geopolymerization products (N-A-S-H) of RAP-FA geopolymer at NaOH/Na2SiO3=100:0 are detected at the early 7days of curing, hence its UCS is lower than that of RAP-FA blend. The 28-day UCS of RAP-FA geopolymers at various NaOH/Na2SiO3 ratios are significantly higher than that of the RAP-FA blend, which can be attributed to the development of geopolymerization reactions. With the input of Na2SiO3, the highly soluble silica from Na2SiO3 reacted with leached silica and alumina from FA and RAP and with free calcium from FA and RAP; hence the coexistence of N-A-S-H gel and C-A-S-H products. Therefore, the 7-day UCS values of RAP-FA geopolymers increase with decreasing NaOH/Na2SiO3 ratio. TCLP results demonstrated that there is no environmental risk for both RAP-FA blends and RAP-FA geopolymers in road construction. The geopolymer binder reduces the leaching of heavy metal in RAP-FA mixture. The outcomes from this research will promote the move toward increased applications of recycled materials in a sustainable manner in road construction.

  9. PAH volatilization following application of coal-tar-based pavement sealant

    Science.gov (United States)

    Van Metre, Peter C.; Majewski, Michael S.; Mahler, Barbara J.; Foreman, William T.; Braun, Christopher L.; Wilson, Jennifer T.; Burbank, Teresa L.

    2012-01-01

    Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, have recently been identified as a source of volatile PAHs to the atmosphere. We tracked the volatilization of PAHs for 1 year after application of a coal-tar-based pavement sealant by measuring gas-phase PAH concentrations above the pavement surface and solid-phase PAH concentrations in sealant scraped from the surface. Gas-phase concentrations at two heights (0.03 and 1.28 m) and wind speed were used to estimate volatilization flux. The sum of the concentrations of eight frequently detected PAHs (ΣPAH8) in the 0.03-m sample 1.6 h after application (297,000 ng m-3) was about 5000 times greater than that previously reported for the same height above unsealed parking lots (66 ng m-3). Flux at 1.6 h after application was estimated at 45,000 μg m-2 h-1 and decreased rapidly during the 45 days after application to 160 μg m-2 h-1. Loss of PAHs from the adhered sealant also was rapid, with about a 50% decrease in solid-phase ΣPAH8 concentration over the 45 days after application. There was general agreement, given the uncertainties, in the estimated mass of ΣPAH8 lost to the atmosphere on the basis of air sampling (2–3 g m-2) and adhered sealant sampling (6 g m-2) during the first 16 days after application, translating to a loss to the atmosphere of one-quarter to one-half of the PAHs in the sealcoat product. Combining the estimated mass of ΣPAH8 released to the atmosphere with a national-use estimate of coal-tar-based sealant suggests that PAH emissions from new coal-tar-based sealcoat applications each year (~1000 Mg) are larger than annual vehicle emissions of PAHs for the United States.

  10. 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.

  11. Numerical analysis of road pavement thermal deformability, based on Biot viscoelastic model of porous medium

    Science.gov (United States)

    Bartlewska-Urban, Monika; Zombroń, Marek; Strzelecki, Tomasz

    2016-03-01

    The following study presents numerical calculations for establishing the impact of temperature changes on the process of distortion of bi-phase medium represented using Biot consolidation equations with Kelvin-Voigt rheological skeleton presented, on the example of thermo-consolidation of a pavement of expressway S17. We analyzed the behavior of the expressway under the action of its own weight, dynamic load caused by traffic and temperature gradient. This paper presents the application of the Biot consolidation model with the Kelvin-Voigt skeleton rheological characteristics and the influence of temperature on the deformation process is taken into account. A three-dimensional model of the medium was created describing the thermal consolidation of a porous medium. The 3D geometrical model of the area under investigation was based on data obtained from the land surveying and soil investigation of a 200 m long section of the expressway and its shoulders.

  12. Pavement Snow Melting

    Energy Technology Data Exchange (ETDEWEB)

    Lund, John W.

    2005-01-01

    The design of pavement snow melting systems is presented based on criteria established by ASHRAE. The heating requirements depends on rate of snow fall, air temperature, relative humidity and wind velocity. Piping materials are either metal or plastic, however, due to corrosion problems, cross-linked polyethylene pipe is now generally used instead of iron. Geothermal energy is supplied to systems through the use of heat pipes, directly from circulating pipes, through a heat exchanger or by allowing water to flow directly over the pavement, by using solar thermal storage. Examples of systems in New Jersey, Wyoming, Virginia, Japan, Argentina, Switzerland and Oregon are presented. Key words: pavement snow melting, geothermal heating, heat pipes, solar storage, Wyoming, Virginia, Japan, Argentina, Klamath Falls.

  13. 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.

  14. Automated pavement horizontal curve measurement methods based on inertial measurement unit and 3D profiling data

    Directory of Open Access Journals (Sweden)

    Wenting Luo

    2016-04-01

    Full Text Available Pavement horizontal curve is designed to serve as a transition between straight segments, and its presence may cause a series of driving-related safety issues to motorists and drivers. As is recognized that traditional methods for curve geometry investigation are time consuming, labor intensive, and inaccurate, this study attempts to develop a method that can automatically conduct horizontal curve identification and measurement at network level. The digital highway data vehicle (DHDV was utilized for data collection, in which three Euler angles, driving speed, and acceleration of survey vehicle were measured with an inertial measurement unit (IMU. The 3D profiling data used for cross slope calibration was obtained with PaveVision3D Ultra technology at 1 mm resolution. In this study, the curve identification was based on the variation of heading angle, and the curve radius was calculated with kinematic method, geometry method, and lateral acceleration method. In order to verify the accuracy of the three methods, the analysis of variance (ANOVA test was applied by using the control variable of curve radius measured by field test. Based on the measured curve radius, a curve safety analysis model was used to predict the crash rates and safe driving speeds at horizontal curves. Finally, a case study on 4.35 km road segment demonstrated that the proposed method could efficiently conduct network level analysis.

  15. Use of Reclaimed Asphalt Pavement in Conjunction with Ground Improvement: A Case History

    Directory of Open Access Journals (Sweden)

    Kevin C. Foye

    2011-01-01

    Full Text Available The use of Reclaimed Asphalt Pavement (RAP in lieu of virgin crushed stone aggregate is becoming a widely accepted practice for a number of construction applications, particularly pavement base courses. A number of laboratory RAP studies have considered the mechanical properties of RAP bases in order to support pavement designs incorporating RAP. These studies have revealed a number of interesting relationships between RAP moisture content, compaction, and stiffness. This paper discusses the experiences of a design-build contractor integrating a geosynthetic ground improvement program with a RAP base during the reconstruction of a 1.95 ha asphalt parking lot. Field observations of base course construction with RAP explore some of the implications of laboratory findings. A number of interesting observations on the technical, construction, and economic issues resulting from the project challenges and the use of RAP are presented.

  16. 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.

  17. 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.

  18. Road pavement condition mapping and assessment using remote sensing data based on MESMA

    Science.gov (United States)

    Pan, Y.; Zhang, X.; Jin, X.; Yu, H.; Rao, J.; Tian, S.; Luo, L.; Li, C.

    2016-04-01

    Remote sensing can be used to monitor changes of asphalt pavement condition because of the spectral change of aged asphalt material. However, owing to coarse spatial resolution of images and the limited width of roads ambient land cover types (e.g. vegetation, buildings, and soil) affect the spectral signal and add significant variability and uncertainty to analysis of road conditions. To overcome this problem, Multiple Endmember Spectral Mixture Analysis (MESMA) was tested to map asphalt pavement condition using WorldView-2 satellite imagery with eight bands spanning from visible to near infrared. Results indicated that MESMA run in a three-endmember model models mixed-pavement pixels well with a low average RMSE (0.01).

  19. Concrete Pavement Joint Deterioration

    OpenAIRE

    2016-01-01

    Concrete pavements are an important part of our national infrastructure. In recent years the relatively small number of reported joints deteriorating prematurely in concrete pavements around Indiana has increased. Changes over the past 45 years in INDOT specification, pavement materials, designs and construction practices, and current de-icing materials were examined and related to the durability of concrete at the joints of existing pavements. A survey of concrete pavements across the state ...

  20. Mechanistic Methodology for Airport Pavement Design with Engineering Fabrics. Volume 1. Theoretical and Experimental Bases.

    Science.gov (United States)

    1984-08-01

    DOTIFAAIPM-8419,, Mechanistic Methodology for Program Engineering& Airport Pavement Design with Maintenance Service Engineerin Washington, D.C. 20591...Reflective cracks require labor intensive operations for crack sealing and patching, thus becoming a significant maintenance expense item. The problem of...models or prediciting allowable critical strains are not available. The problems are complicated further by the fact that since asphaltic concrete is a

  1. 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

  2. Pavement management and rehabilitation of portland cement concrete pavements

    Science.gov (United States)

    Zegeer, C. V.; Agent, K. R.; Rizenbergs, R. L.; Curtayne, P. C.; Scullion, T.; Pedigo, R. D.; Hudson, W. R.; Roberts, F. L.; Karan, M. A.; Haas, R.

    Pavement management and rehabilitation projects and techniques are discussed. The following topics are discussed: economic analyses and dynamic programming in resurfacing project selection; implementation of an urban pavement management system; pavement performance modeling for pavement management; illustration of pavement management: from data inventory to priority analysis; rehabilitation of concrete pavements by using portland cement concrete overlays; pavement management study: Illinois tollway pavement overlays; resurfacing of plain jointed-concrete pavements; design procedure for premium composite pavement; model study of anchored pavement; prestressed concrete overlay at O'Hare International Airport: in-service evaluation; and, bonded portland cement concrete resurfacing.

  3. Marginal Aggregates in Flexible Pavements: Background Survey and Experimental Plan

    Science.gov (United States)

    1994-08-01

    cement, bitumen , and water has been marketed in France under the trade name Stabicol 71 , but it is not yet available in the U.S. This composite...in a pavement base course. Geotextile reinforcement and a new portland cement- bitumen emulsion have considerable potential to upgrade substandard...modifiers with SBS , polyethylene. 30 b) Hard Asphalt Cement - AC 40 asphalt cement. c) Large Stone Asphalt Mixtures - Increase maximum aggregate size. e

  4. 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

  5. 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.

  6. 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.

  7. Load Response Analysis of Asphalt Pavement

    Directory of Open Access Journals (Sweden)

    Xiao Zhijun

    2016-01-01

    Full Text Available Based on the filed data of Fuzhou test road, load response regulation of nonlinear pavement structure was analyzed in this paper; Mechanics software was adopted to analyze linear elastic and nonlinear of the pavement structure, analyzed results and road filed data were compared, and determine the correlation between them and the field data.

  8. Sub-base Construction of Silt Pavement%粉砂土路面底基层施工

    Institute of Scientific and Technical Information of China (English)

    童旬宁

    2011-01-01

    The sub-base construction of freeway is the construction project that highway industry has concerned and been paid attention to for many years.For the sub-base construction of silt pavement, its application is not extensive in China.After the Development of the West Regions, people started to pay attention to the northwest region.Aiming at the desert land silt landscape of Yulin area in Shaanxi Province, this paper summed up the experience from long-term sub-base construction of silt pavement, to provide reference for the person who had engaged in related industry.%高速公路底基层施工,是公路界多年关注和重视的建设项目.对于粉砂土路面底基层施工,虽在国内公路施工中运用不广泛.国家进行西部经济大开发以后,在西北地区已经开始面临重视和研究,本文针对陕西省榆林地区特殊的沙漠粉砂土地貌,从长期的粉砂土路面底基层施工取得经验进行总结,对从事相关工作业内同仁有显著借鉴,可供参考.

  9. 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...

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Porous pavement. Phase 1: Design and operational criteria

    Science.gov (United States)

    Diniz, E. V.

    1980-08-01

    Utilization concepts, benefits and disadvantages, as well as other characteristics of porous pavements are presented with emphasis on porous asphalt pavements, but the criteria and design approach are applicable to all other porous pavement types. Design considerations include siting problems, load bearing design and hydrologic design. The history of porous pavement development and previous experience with porous pavement by several designers, contractors and operators are described. A computer model for hydrologic performance evaluation of existing or proposed porous pavement systems is also examined. Load bearing design criteria are based on previous work conducted for porous asphalt pavements. Appendices include a sample set of specifications for porous asphalt construction and a list of soils and their permeability classes as prepared by the U.S. Soil Conservation Service.

  16. Evaluation of bituminous materials used in pavement recycling projects at Tyndall, MacDill, and Hurlburt Air Force Bases

    Science.gov (United States)

    Kiggundu, B.; Martinez, R.; Humphrey, B.; Shuler, T.

    1987-07-01

    This report presents results of a study involving bituminous materials from Tyndall and MacDill Air Force Bases and Hurlburt Field. These materials included Reclaimed Asphalt Pavement (RAP), modifiers, virgin asphalts, and new aggregates. A tentative modifier selection criterion was used to judge the quality of materials used in the recycling efforts at the respective sites. The results showed that independent adequacy of physical properties from chemical properties in selection of modifiers could not be established. However, some of the results showed that physical properties were more sensitive indicators of changes in binders due to aging. In addition, this report includes the tentative modifier selection criteria and results of an interlaboratory study from which variability limits to parameters determined using modified Clay-Gel and Heithaus procedures are established. The modified Clay-Gel and Heithaus procedures are included.

  17. STUDY ON FLOOD CONTROL PROPERTIES OF PERMEABLE PAVEMENT USING SATURATED-UNSATURATED SEEPAGE ANALYSIS

    Science.gov (United States)

    Yano, Takao; Nishiyama, Satoshi; Ohnishi, Yuzo; Nakashima, Shinichiro; Moriishi, Kazushi; Wada, Minoru

    The rainfall storage and infiltration facility of permeable pavement have been attracted attention as a control measure of flood and an environmental improvement measure in urban areas. However, rainfall infiltration of permeable pavement is unsteady flow and strongly dependent on the behavior of unsaturated zones in the pavement. Moreover, the wet condition of subbase course also has a great influence on the rainfall infiltration of the pavement. That's why previous studies have not made clear the precise the facility of permeable pavement as a flood control. In this paper, experimental studies and simulated analyses were performed to measure the overflow from the pavement under various conditions of rainfall intensities and estimate the rainfall infiltration of the pavement using the measurement data and unsaturated infiltration characteristics of porous asphalt materials. It is clear that this study shows the methods to have a quantitative estimation of the rainfall storage and infiltration facility of permeable pavement.

  18. 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

  19. 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.

  20. Pavement Testing Facility

    Data.gov (United States)

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

  1. 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...

  2. 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...... elements for such a European design method. During the course of the Action, 20 countries signed the Memorandum of Understanding and participated in the work, thus showing a very high level of interest in the work programme and results.The document contains a very thorough review of the position in Europe...... at the present time and identifies the basic framework for a design method. It then clearly shows the necessary steps to be taken in the future in order to arrive at a method based on current best practice in the shorter term, and then to move to improved versions....

  3. Network-based Database Course

    DEFF Research Database (Denmark)

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

    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......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...

  4. 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.

  5. 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…

  6. Concrete Block Pavements

    Science.gov (United States)

    1983-03-01

    1967, Cedergren 1974, Federal Highway .’,U .. V,47 -’":: 37 Administration 1980). Block pavements have essentially the same prob- lems with moisture...Vicksburg, Miss. Cedergren , H. R. 1974. Drainage of Highway and Airfield Pavements, John Wiley and Sons, New VOk. I Cement and Concrete Association

  7. 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...

  8. 基于动态参数的新型半刚性沥青混凝土路面结构力学分析%Mechanical Analysis on the New Type of Semi-Rigid Asphalt Pavement Structure Based on Dynamic Parameters

    Institute of Scientific and Technical Information of China (English)

    陈团结; 刘宁

    2013-01-01

    In order to study the dynamic response of the new type of semi-rigid asphalt pavement structure under different speed and continuous variable speed of vehicle,the 3D finite element model is built by ABAQUS based on the elastic layered system theory,the dynamic modulus parameters of pavement materials are utilized,and the subroutine UTRACLOAD and DSLOAD are compiled.In addition,mechanical responses of pavement structure calculated by static parameters are compared.And difference of mechanical performance indexes between new semi-rigid and the traditional pavement structure are also analysed.The results show that the vehicle speed has few effects on dynamic responses of pavement structure.Compared to the calculations by static modulus,strain of semi-rigid base layer is reduced and shear stress of asphalt surface course is increased when dynamic modulus is used.Furthermore,the new type of semi-rigid pavement structure can effectively reduce the rutting probability of intersections and improve its resistance to permanent deformation.%基于弹性层状体系理论,借助大型有限元软件ABAQUS建立了新型半刚性路面结构三维有限元模型,引入铺面材料动态模量参数,并编写了UTRACLOAD和DLOAD用户子程序,研究不同车速以及连续变速下的路面结构动力响应,与基于静态参数的路面结构力学响应进行了对比;并分析了特定车速下新型半刚性路面结构与传统路面结构各力学性能指标的差异.结果表明;车速对路面结构各动力响应值的影响较小;车辆在连续变速时,路面结构上中面层受到了更为不利的剪应力作用;相比于静态模量,采用动态模量分析的半刚性基层层底拉应变减小,而沥青混凝土上面层剪应力水平增加;新型半剐性路面结构能有效降低交叉口路段车辙情况发生的几率,提高其抗永久变形能力.

  9. 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。

  10. 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.

  11. 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。

  12. 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.

  13. 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,…

  14. 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 Perfo...

  15. 半刚性基层双层排水降噪沥青路面结构计算分析%Calculation and Analysis on Double Drainage Noise Reduction Asphalt Pavement Structure of Semi-rigid Base

    Institute of Scientific and Technical Information of China (English)

    汪军伟

    2016-01-01

    双层排水降噪路面具有显著的排水和降噪性能,在欧洲国家得到越来越多的应用,但都是基于柔性基层的路面结构。通过对基于半刚性基层的普通沥青路面、单层排水降噪沥青路面和双层排水降噪沥青路面结构的弯沉、层底拉应力进行计算分析,并对不同路面结构进行比较分析,衡量半刚性基层双层排水降噪沥青路面结构的可行性。计算结果表明,半刚性基层双层排水降噪沥青路面顶面的弯沉值小于路面设计弯沉值,路面结构强度满足设计要求。%Double drainage noise reduction pavement has significant drainage and noise reduction per-formance,which gets more and more applications in European countries,but they are based on the pavement structure of flexible base layer.The calculation and analysis on the deflection and bottom layer tensile stress of ordinary asphalt pavement,single drainage noise reduction asphalt pavement, and double drainage noise reduction asphalt pavement are performed based on the semi-rigid base,and the comparative analysis of different pavement structures are made to measure the feasibility of double drainage noise reduction asphalt pavement of semi-rigid base.The results show that,the top surface deflection of double drainage noise reduction pavement of semi-rigid base is less than the design value, and the pavement structural strength meets the design requirements.

  16. WEB BASED LEARNING OF COMPUTER NETWORK COURSE

    Directory of Open Access Journals (Sweden)

    Hakan KAPTAN

    2004-04-01

    Full Text Available As a result of developing on Internet and computer fields, web based education becomes one of the area that many improving and research studies are done. In this study, web based education materials have been explained for multimedia animation and simulation aided Computer Networks course in Technical Education Faculties. Course content is formed by use of university course books, web based education materials and technology web pages of companies. Course content is formed by texts, pictures and figures to increase motivation of students and facilities of learning some topics are supported by animations. Furthermore to help working principles of routing algorithms and congestion control algorithms simulators are constructed in order to interactive learning

  17. Basics of a Good Road - Concrete Pavements: Road Scholar Program Part I

    OpenAIRE

    2014-01-01

    This 3-hour course will provide the basic knowledge needed to design, build, and maintain concrete pavements at a local level. Attendees will hear industry experts discuss the many applications for concrete pavements in our industry and the emerging innovations in the field of mix designs and maintenance. Attendees will receive core course credit for core course #6: Basics of a Good Road. Attendees who have already attended this core course will receive 3 Road Scholar points.

  18. Basics of a Good Road - Concrete Pavements: Road Scholar Program Part II

    OpenAIRE

    2014-01-01

    This 3-hour course will provide the basic knowledge needed to design, build, and maintain concrete pavements at a local level. Attendees will hear industry experts discuss the many applications for concrete pavements in our industry and the emerging innovations in the field of mix designs and maintenance. Attendees will receive core course credit for core course #6: Basics of a Good Road. Attendees who have already attended this core course will receive 3 Road Scholar points.

  19. 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.

  20. PAH concentrations in lake sediment decline following ban on coal-tar-based pavement sealants in Austin, Texas

    Science.gov (United States)

    Van Metre, Peter C.; Mahler, Barbara J.

    2013-01-01

    Recent studies have concluded that coal-tar-based pavement sealants are a major source of polycyclic aromatic hydrocarbons (PAHs) in urban settings in large parts of the United States. In 2006, Austin, TX, became the first jurisdiction in the U.S. to ban the use of coal-tar sealants. We evaluated the effect of Austin’s ban by analyzing PAHs in sediment cores and bottom-sediment samples collected in 1998, 2000, 2001, 2012, and 2014 from Lady Bird Lake, the principal receiving water body for Austin urban runoff. The sum concentration of the 16 EPA Priority Pollutant PAHs (∑PAH16) in dated core intervals and surficial bottom-sediment samples collected from sites in the lower lake declined about 44% from 1998–2005 to 2006–2014 (means of 7980 and 4500 μg kg–1, respectively), and by 2012–2014, the decline was about 58% (mean of 3320 μg kg–1). Concentrations of ∑PAH16 in bottom sediment from two of three mid-lake sites decreased by about 71 and 35% from 2001 to 2014. Concentrations at a third site increased by about 14% from 2001 to 2014. The decreases since 2006 reverse a 40-year (1959–1998) upward trend. Despite declines in PAH concentrations, PAH profiles and source-receptor modeling results indicate that coal-tar sealants remain the largest PAH source to the lake, implying that PAH concentrations likely will continue to decline as stocks of previously applied sealant gradually become depleted.

  1. Mechanics Analysis of Asphalt Treated Permeable Base Pavement%沥青稳定碎石排水基层沥青路面结构力学行为分析

    Institute of Scientific and Technical Information of China (English)

    付军明; 孔令伟; 柯昌波; 党高峰

    2014-01-01

    开级配沥青稳定碎石排水基层沥青路面结构受力特性与传统半刚性基层沥青路面不同,应用基于多层弹性层状体系理论的 BISAR软件通过改变各个结构层的厚度和模量两个因素,计算得到了路面层底应力、最大剪应力和弯沉等力学指标的变化规律,对确定合理沥青稳定碎石排水基层沥青路面结构具有一定指导意义。%The mechanical characteristics of Asphalt treated permeable base (ATPB )is different from one of the traditional semi-rigid base asphalt pavement.Through the range of pavement thickness and modulus the Pavement stresses,Maximum shear stress and deflection are calculated by BISAR.The change law of mechanical characteristics of ATPB asphalt pavement is obtained in this paper.It can be re-fer to determine the ATPB asphalt pavement structure parameter.

  2. 加铺超薄罩面后沥青路面就地热再生适用性分析%Applicability Analysis of Asphalt Pavement Hot in Place Recycling of Ultra-thin Wearing Course

    Institute of Scientific and Technical Information of China (English)

    张怀宇; 张剑波

    2014-01-01

    This paper analyzes ultra-thin wearing course material.The results and analyses show that gradation and asphalt aggregate ratio of the material meet the standard of AC-13 Technology,and ul-tra-thin wearing course material can be regenerated.High temperature stability,moisture stability,low temperature property meet the requirements of HMA in specifications.Pavement compactness,smooth-ness,water permeability coefficient index can meet the requirements of specification after regeneration.%对加铺超薄磨耗层后的路面沥青混合料进行试验分析。试验结果与分析表明:加铺超薄磨耗层后的混合料级配和油石比满足规范的 AC-13的技术要求,说明超薄磨耗层路面可进行再生利用。对再生混合料进行高温性能、水稳定性能和低温性能试验,发现含有超薄磨耗层的再生混合料的高温性能、水稳性能和低温性能均满足规范要求。再生后路面压实度、平整度、渗水系数等指标满足规范要求。

  3. 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.

  4. 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.

  5. Depression storage capacities of different ideal pavements as quantified by a terrestrial laser scanning-based method.

    Science.gov (United States)

    Nehls, T; Menzel, M; Wessolek, G

    2015-01-01

    Rainfall partition on paved urban surfaces is governed to a great extent by depression storage. This is especially the case for small rainfall events, which are often ignored in urban hydrology. If storage, infiltration and evaporation (important for urban heat island mitigation), rather than storm water run-off, are of interest, high-resolution simulations with exact values for depression storage capacities are required. Terrestrial laser scanners deliver fast, high-resolution surveys of pavement surface morphology. The depression storage capacity can be quantified from 3D points by generating digital elevation models and applying cut-and-fill algorithms in a geographic information system. The method was validated using a test model. It was possible to quantify depressions with a depth of at least 1.4 × 10(-3) m and a surface of at least 15 × 10(-6) m(2) with an uncertainty below 30%. Applying this method, the depression storage capacities for 11 ideal, typical pavement designs were found to vary from 0.07 to 1.4 mm. Realistic urban pavements must also be surveyed, as cracks and puddles from their use history can have a major impact on the depression storage capacities and thus on infiltration, evaporation and, finally, the annual run-off.

  6. 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

  7. Analysis of finite element and mechanical response in granular base asphalt pavement%粒料基层沥青路面有限元和力学响应分析

    Institute of Scientific and Technical Information of China (English)

    马骁尧; 高启聚

    2016-01-01

    The paper compares mechanical properties of the granular base asphalt pavement and semi-rigid base asphalt pavement by finite ele-ment analysis method. Besides, the paper calculates 34 kinds of representative pavement structures with granular base. The result shows that the surface deflection of granular base is larger than that of semi-rigid base. But the tensile stress below the base layer of asphalt pavement with semi-rigid base is much larger than that of granular base. Meanwhile, the paper provides the principal law and principal range of granular base and granular subbase.%利用有限元分析法,比较分析了粒料基层沥青路面和半刚性基层沥青路面的力学特性,计算了34种具有代表性的粒料基层路面结构的主应力,研究结果表明:粒料基层较半刚性基层会产生更大的路表弯沉;而半刚性基层层底拉应力比粒料基层大得多,同时得到粒料基层、底基层主应力分布规律及分布范围.

  8. Analysis of Force Bearing Properties of Cement Concrete Pavement Base Analysis%水泥混凝土路面基层受力特性分析

    Institute of Scientific and Technical Information of China (English)

    王国业; 胡昌斌; 杨建军; 李生效

    2011-01-01

    Base is an important component of the cement concrete pavement structure.EevrFE 3-D finite element program is adopted to analyze the force bearing properties of the base.When single axle load works on the centre of the slab longitudinal joint edge,the force beating of the base is in the most unfavorable condition,and the closer the cohesion of the interlayer is ,the greater the base stress is.The base stress increases in accordance with the increase of the base module, but decreases with the increase of the pavement slab thickness, the base thickness, the base reaction module and the thickness and module of the base cushion layer.It is found that in comparison with the affecting degrees of all the structural layers on the base stress, the base module and thickness as well as the properfies of the interlayer contact face are the major elements of affecting the force bearing properties of the base.%采用EevrFE三维有限元程序对混凝土基层的受力特性进行分析.当单轴轴载作用于板纵缝边缘中部时,基层受力最为不利,层间粘结越紧密基层应力越大;基层应力随基层模量的增加而增大,但随路面板厚度、基层厚度和地基反应模量以及垫层厚度和模量的增大而降低.对比各结构层对基层应力的影响程度发现,基层模量和厚度以及层间接触界面特性是影响基层受力特性的主要因素.

  9. 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.

  10. Coal-tar-based sealcoated pavement: a major PAH source to urban stream sediments.

    Science.gov (United States)

    Witter, Amy E; Nguyen, Minh H; Baidar, Sunil; Sak, Peter B

    2014-02-01

    We used land-use analysis, PAH concentrations and assemblages, and multivariate statistics to identify sediment PAH sources in a small (~1303 km(2)) urbanizing watershed located in South-Central, Pennsylvania, USA. A geographic information system (GIS) was employed to quantify land-use features that may serve as PAH sources. Urban PAH concentrations were three times higher than rural levels, and were significantly and highly correlated with combined residential/commercial/industrial land use. Principal components analysis (PCA) was used to group sediments with similar PAH assemblages, and correlation analysis compared PAH sediment assemblages to common PAH sources. The strongest correlations were observed between rural sediments (n = 7) and coke-oven emissions sources (r = 0.69-0.78, n = 5), and between urban sediments (n = 22) and coal-tar-based sealcoat dust (r = 0.94, n = 47) suggesting that coal-tar-based sealcoat is an important urban PAH source in this watershed linked to residential and commercial/industrial land use.

  11. Precast Concrete Pavements

    Science.gov (United States)

    1981-11-01

    Gorsuch 1962, Kruse 1966, Jacoby 1967, and Hargett 1970). The final slab design used in construction is shown in Figure 2. These slabs were 6 ft wide, 24...Experiment Station, CE, Vicksburg, Miss. Gorsuch , R. F. 1962. "Preliminary Investigation of Precast Prestressed Concrete Pavements," MS Thesis, South Dakota

  12. A Computer-based Course in Classical Mechanics.

    Science.gov (United States)

    Kane, D.; Sherwood, B.

    1980-01-01

    Describes and illustrates the tutorial and homework exercise lessons, student routing, course organization, administration, and evaluation of a PLATO computer-based course in classical mechanics. An appendix lists 41 lessons developed for the course. (CMV)

  13. Prediction of Rutting of Asphalt Pavement Based on Combined Model%基于组合模型的沥青路面车辙预测

    Institute of Scientific and Technical Information of China (English)

    张琛; 汪海年; 王宠惠

    2016-01-01

    To predict the rutting of asphalt pavement, Pavement-Me prediction model ( PME) with the localized input parameter and a dynamic grey prediction model (DGM (1,1)) with data timeliness were established based on the PME and grey prediction theory, in the current rutting situation in a highway of Shaanxi Province. The mathematical statistic method was used to conduct the prediction research of rutting based on a combined model. The results reveal that the fitting precision of PME model is 0. 963, and the DGM (1,1) model is 0. 941, which can be used as a submodel of the combined model. The prediction precision of DGM-PME combined model is higher than that of single submodel, in which the combined model which adopts error square and reciprocal weighting has the highest prediction precision, and its rank allocation is L12 =0. 601 and L22 =0. 399, the maximum of prediction precision can be 0. 0045 . The prediction result of the combined model at some periods is inferior to that of some single prediction models, which belongs to normal error range. It is feasible to replace the single model with the DGM-PME combined model to predict the rutting of asphalt pavement. And it is more suitable to use the combined model established in this paper to predict rutting development tendency for the project-level asphalt pavement.%为了对沥青路面车辙进行预测研究,结合陕西某高速公路沥青路面的车辙病害现状,以美国AASHTO新力学经验法中的Pavement-ME预测模型( PME模型)和灰色预测理论为基础,对PME预测模型的参数进行了本地化处理,提出了考虑数据时效的动态灰色预测模型DGM (1,1),并采用数理统计方法对车辙的发育趋势进行基于组合模型的预测研究.研究结果表明:PME模型和DGM灰色模型的拟合精度分别为0.963和0.941,可以作为组合模型的子模型;DGM-PME组合模型的预测精度要高于单一子模型的预测精度,其中采用误差平方和倒数法定权得到

  14. 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;

  15. 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

  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. 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 managem...... 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....... management and sustainable land use. The SLUSE (Sustainable Land Use and Natural Resource Management) project, under which these courses were devised, is introduced and the process of field-course implementation is described. The SLUSE approach is discussed in terms of management issues, levels...... of responsibility, staff and student development and the benefits to rural host communities. The courses are very intense experiences and Students encounter difficulties working across traditional academic disciplines and in cross-cultural groups. Through critical thinking and self-reflection students understand...

  19. 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.

  20. Grout Impregnation of Pre-Placed Recycled Concrete Pavement (RCP) for Rapid Repair of Deteriorated Portland Cement Concrete Airfield Pavement

    Science.gov (United States)

    2007-04-01

    Hammitt (1985) also reports a high failure rate when using cold mix asphalt for crater repairs and recommended that it be abandoned as a technique...cement-treated base, embankment base material, and aggregate for asphalt paving mixtures . RCP has been used successfully for all of these types of...that recycled asphalt pavement ( RAP ) and RCP have a substantial history of usage in pavement construction. He reports that cost savings of 20 to

  1. Striated clast pavements: Products of deforming subglacial sediment?

    Science.gov (United States)

    Clark, Peter U.

    1991-05-01

    Studies of modern glaciers have recently drawn attention to the importance of subglacial sediment deformation to glacier dynamics and processes. Inferences regarding the probable shear strength of this sediment imply that large clasts may in some cases sink to underlying rigid sediment, where abrasion by overlying deforming sediment could occur. This scenario provides a formative mechanism for striated clast pavements commonly described from the base of fine-grained massive diamictons associated with the late Pleistocene Laurentide ice sheet. Such a mechanism indicates that, at the time of formation of clast pavements, overlying diamictons associated with pavements had a low yield strength (≤0.5 kPa) and were deforming mechanically like a debris flow. Clast pavements may therefore be an important criterion for recognition of sediments deposited by subglacial deformation transport.

  2. ANALYSIS OF GROUP MAINTENANCE STRATEGY -ROAD PAVEMENT AND SEWERAGE PIPES-

    Science.gov (United States)

    Tanimoto, Keishi; Sugimoto, Yasuaki; Miyamoto, Shinya; Nada, Hideki; Hosoi, Yoshihiko

    Recently, it is critical to manage deteriorating sewerage and road facilities efficiently and strategically. Since the sewerage pipes are mostly installed under road pavement, the works for the replacement of the sewerage pipes are partially common to the works for the road. This means that the replacement cost can be saved by coordinating the timing of the replacements by sewerage pipe and road pavement. The purpose of the study is to develop the model based on Markov decision process to derive the optimal group maintenance policy so as to minimize lifecycle cost. Then the model is applied to case study area and demonstrated to estimate the lifecycle cost using statistical data such as pipe replacement cost, road pavement rehabilitation cost, and state of deterioration of pipes and road pavement.

  3. 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…

  4. 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.

  5. Pre-Cast Concrete Panels for Contingency Rigid Airfield Pavement Damage Repairs

    Science.gov (United States)

    2010-06-01

    transfer mechanism in rigid pavements . Load transfer is essentially a design parameter that characterizes the reduction in the stresses and strains in the...the PCC slabs at the joints. Therefore, pavement responses such as stresses and strains are significantly lower compared to situations where no load...presented in Appendix C. Another method to calculate the load transfer efficiency in rigid pavements is based on the stresses under the PCC slabs at

  6. Sensitivity analysis of longitudinal cracking on asphalt pavement using MEPDG in permafrost region

    OpenAIRE

    Chen Zhang; Hainian Wang; Zhanping You; Biao Ma

    2015-01-01

    Longitudinal cracking is one of the most important distresses of asphalt pavement in permafrost regions. The sensitivity analysis of design parameters for asphalt pavement can be used to study the influence of every parameter on longitudinal cracking, which can help optimizing the design of the pavement structure. In this study, 20 test sections of Qinghai–Tibet Highway were selected to conduct the sensitivity analysis of longitudinal cracking on material parameter based on Mechanistic-Empiri...

  7. 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.

  8. 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

  9. 高性能沥青混凝土机场道面结构%Airfield pavement with high performance asphalt concrete

    Institute of Scientific and Technical Information of China (English)

    钱振东; 孟凡奇; 曾靖

    2015-01-01

    To improve the anti-rutting performance of airfield pavement, a high performance airfield pavement based on a new type of epoxy asphalt concrete was proposed.With the new type of epoxy asphalt concrete EAC20 as the middle surface course, SMA13 asphalt concrete as the first surface course, and AC20 asphalt concrete as the base surface course, the SEA airfield pavement was built up.The mechanical responses of the SEA airfield pavement under the static loads of the aircraft A380 were analyzed.The permanent deformation tests of the asphalt concrete in different airfield pavement layers were carried out.The creep parameters of the asphalt concrete in each layer were obtained by using the multiple linear regression method to simulate the permanent deformation of the SEA airfield pavement.The results demonstrate that taking the new type of epoxy asphalt concrete as the middle surface course can reduce the strain of the airfield pavement.The maximum tensile strain and the maximum compressive strain on the bottom of the asphalt surface course are respectively about 68%and 72%those of the traditional airfield pavement.Under 1 ×105 loads, the permanent deformation of the SEA airfield pavement is only 6 mm, which is about 42.9%that of the traditional SAA airfield pavement.%为增强机场沥青道面的抗轮辙性能,提出了一种基于新型环氧沥青混凝土的高性能机场道面结构.将新型环氧沥青混凝土EAC20作为机场道面的中面层,SMA13型沥青混凝土作为上面层,AC20型沥青混凝土作为下面层,由此构成SEA机场道面结构.分析了新一代大型客机A380荷载作用下SEA机场道面结构的力学响应,针对机场道面各层沥青混凝土进行永久变形试验,并采用多元线性回归得到各层材料的蠕变参数,以模拟SEA机场道面结构的永久变形.研究结果表明,将新型环氧沥青混凝土作为中面层应用于机场道面,可以减小机场道面结构的应变,沥

  10. 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.

  11. Web-Based Gerontology Courses: How Do They Measure Up?

    Science.gov (United States)

    Hills, William E.; Brallier, Sara A.; Palm, Linda J.; Graham, Jamie M.

    2009-01-01

    This study compared Web-based and lecture-based Gerontology and Psychology of Aging courses in terms of student performance, demographic and academic characteristics of students enrolled in the courses, and extent to which these characteristics differentially predicted outcomes of learning in the two course types. Participants for this study were…

  12. 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.

  13. 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.

  14. 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.

  15. Analysis for Dynamic Response of Semi-Rigid Base Asphalt Pavement Based on APT Test%基于 APT 试验的半刚性基层沥青路面动力响应分析

    Institute of Scientific and Technical Information of China (English)

    庄传仪; 叶亚丽; 张宁

    2014-01-01

    In this article, the dynamic response of the semi-rigid asphalt pavement is studied through the acceleration and loading test on the full-scale test road , which provides the basis for the prediction and structural design of pavement performance .Through the APT test road construction with the two structures of cement stabilized macadam and lime-fly ash stabilized macadam , strain gauges , vertical stress sensors and temperature sensors are laid to make the real-time collection of the dynamic stress , strain and deflection of the pavement structure as well as the pavement temperature field , to analyze the correlation between the temperature and the responses of the structural dynamic strain and stress and also the calculation of the pavement layer moduli and mechanical response based on the FWD deflection basin .The research results are as follows .The tensile strain of semi-rigid base layer is less affected by temperature .The structural deflection is greatly affected by the thickness of the semi-rigid base .The thinner the semi-rigid base thickness is , the faster the decline of its modulus is .With the function of repeated loads , the declining rate of tensile strain of semi-rigid base layer increases first and then slowly decreases .In the early service ( less than 25 .6 million times of standard axle loads) , the modulus of the semi-rigid base decays slowly and when the pavement is loaded with 100 million cumulative equivalent standard axle loads , its modulus decays about 55%.%通过足尺试验路加速加载试验研究半刚性基层沥青路面的动力响应,为路面性能预估及结构设计提供依据。通过修筑水泥稳定碎石基层和二灰稳定碎石基层2种结构APT试验路,埋设水平应变仪、竖向压应力传感器和温度传感器,实时采集路面结构动应力、应变、弯沉和路面温度场,分析温度与结构动应变、应力响应的关系,开展基于FWD弯沉盆的路面结构层模量

  16. 沥青稳定碎石基层对沥青路面力学的特性影响分析%Asphalt Macadam Mechanical Properties of Asphalt Pavement Impact Analysis

    Institute of Scientific and Technical Information of China (English)

    陈勇军

    2012-01-01

    Asphalt stabilized gravel base course can significantly reduces the number of early damage to asphalt pavement. Through using three-dimensional finite element method, the mechanical performance of asphalt pavement structure added asphalt stabilized gravel base is analyzed, and stress and strain of asphalt pavement structure is also analyzed. Performance requirement of drainage base materials is proposed from the point of structural, and the structure design recommendation of semi-rigid base of the asphalt pavement added asphalt stabilized gravel base course is put forward.%沥青稳定碎石基层可以显著减少沥青路面一些早期损害,通过采用ABAQUS三维有限元方法,对设置沥青稳定碎石基层的沥青路面结构进行力学性能分析,分析路面结构应力和应变的影响.从结构角度提出对沥青稳定碎石基层材料的性能的要求,并且对设置排水基层的半刚性基层沥青路面结构设计提出相应建议.

  17. Problem-based learning biotechnology courses in chemical engineering.

    Science.gov (United States)

    Glatz, Charles E; Gonzalez, Ramon; Huba, Mary E; Mallapragada, Surya K; Narasimhan, Balaji; Reilly, Peter J; Saunders, Kevin P; Shanks, Jacqueline V

    2006-01-01

    We have developed a series of upper undergraduate/graduate lecture and laboratory courses on biotechnological topics to supplement existing biochemical engineering, bioseparations, and biomedical engineering lecture courses. The laboratory courses are based on problem-based learning techniques, featuring two- and three-person teams, journaling, and performance rubrics for guidance and assessment. Participants initially have found them to be difficult, since they had little experience with problem-based learning. To increase enrollment, we are combining the laboratory courses into 2-credit groupings and allowing students to substitute one of them for the second of our 2-credit chemical engineering unit operations laboratory courses.

  18. 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.

  19. 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.

  20. 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.

  1. 基于3D数据和双尺度聚类算法的路面裂缝检测%Pavement Crack Detection Based on Two-Scale Clustering Algorithm and 3D Data

    Institute of Scientific and Technical Information of China (English)

    李伟; 呼延菊; 沙爱民; 孙朝云; 郝雪丽

    2015-01-01

    为了更加准确高效地识别路面裂缝,提出一种基于路面3D数据和双尺度聚类算法的路面裂缝检测技术.首先,使用中值滤波以及Otsu阈值分割算法对采集到的路面裂缝3D数据进行预处理,获得二值化的路面裂缝图像,在此基础上,将不规则的路面裂缝区域使用规则椭圆模型表征为裂缝基本单元,作为聚类基础.然后,使用双尺度准则函数从最优化中心距离以及角度偏差两个尺度上对基本裂缝单元进行聚类识别.最后借助杠杆原理确定聚类后裂缝中心点位置,使用最小外接椭圆表征聚类后的实际裂缝区域,并使用圆形度因子进行了路面裂缝类型判断,对网状裂缝进行了路面破损程度参数分析,为路面破损程度量化分析提供了参考因子.实际路面裂缝的实验表明,文中方法具有良好的路面裂缝检测精度.%In order to identify the pavement cracks more accurately and efficiently, a kind of two-scale clustering pavement crack recognition method is proposed based on 3D data.First, the 3D data of pavement cracks are pre-treated by means of the median filtering and the Otsu threshold segmentation algorithm, and the binary pavement crack images are thus obtained.Next, the irregular pavement crack area is characterized by a regular elliptical crack model as the basic unit, which represents a cluster basis.Then, the two-scale optimization criterion function is used to identify the basic units from the viewpoints of the distance and the angle deviation.Finally, the center of the final position of the cluster is determined based on the lever principle, and the area of the clustered cracks is characterized by using the minimum external ellipse of a complete crack.Moreover, the degree of circularity factors are adopted to judge the types of pavement cracks, and the parameters relevant to the damage extent of the road with reticular cracks are analyzed, which provides reference factors for the

  2. Unified Methodology for Airport Pavement Analysis and Design. Volume 1. State of the Art

    Science.gov (United States)

    1991-06-01

    pavements with saturated bases and subgrades to well- drained pavements. The damage factors ranged from 10 to 70,000. Cedergren also demonstrated that...34Modulus of Asphalt Mixtures - An Unresolved Dilemma," Transportation Research Board, Research Record 1171, p. 193, Washington, DC 13. Cedergren , H.R

  3. 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…

  4. 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.

  5. Mechanical Response of Typical Cement Concrete Pavements under Impact Loading

    Directory of Open Access Journals (Sweden)

    Ding Fei

    2017-01-01

    Full Text Available In order to study the mechanical response of cement concrete pavements under impact loading, four types of typical cement concrete pavement structures are investigated experimentally and numerically under an impact load. Full-scale three-dimensional pavement slots are tested under an impact load and are monitored for the mechanical characteristics including the deflection of the pavement surface layer, the strain distribution at the bottom of the slab, and the plastic damage and cracking under the dynamic impact load. Numerical analysis is performed by developing a three-dimensional finite element model and by utilizing a cement concrete damage model. The results show that the calculation results based on the cement concrete damage model are in reasonable agreement with the experimental results based on the three-dimensional test slot experiment. The peak values of stress and strain as monitored by the sensors are analyzed and compared with the numerical results, indicating that the errors of numerical results from the proposed model are mostly within 10%. The rationality of the finite element model is verified, and the model is expected to be a suitable reference for the analysis and design of cement concrete pavements.

  6. 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...

  7. 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

  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...... goal is to fight the trial-and-error approach to programming which is a result of the students battles with horribly designed and documented systems and languages prior to their studies at university. Instead, the authors strive for giving the students a good experience of programming as a systematic......, 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. Work-Based Courses: Bringing College to the Production Line

    Science.gov (United States)

    Kobes, Deborah; Girardi, Amy

    2016-01-01

    Work-based courses are an innovative way to bring college to the production line by using the job as a learning lab. This toolkit provides guidance to community college administrators and faculty who are interested in bringing a work-based course model to their college. It contains video content and teaching tips that introduce the six steps of…

  10. 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…

  11. 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.

  12. 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.

  13. Initiation and Propagation Mechanism of Blisters on the Epoxy Asphalt Concrete Paving Course of Steel Deck Bridge Pavement%钢桥面环氧沥青铺装层鼓泡形成扩展机理

    Institute of Scientific and Technical Information of China (English)

    张华; 郝培文; 张海伟

    2016-01-01

    In order to take effective steps to minimize the blistering problems on the epoxy asphalt overlays, the cause and propagation mechanism for blisters were studied systematically by means of field investigation, theoretical analysis and mathematical modeling. Based on the theory of thin plate and fracture mechanics,the deflection of blisters was studied under the pressure. Additionally, the energy principle in fracture mechanics was used to derive the energy relationship and the initiation and propagation mechanism was studied. The results indicate that the development of blisters includes three stages, namely, initiation, stale and unstable propagation. The deflection of blisters produced by the external force was related to the radius of blisters, depth and modulus of elasticity of pavement. The energy release rate was proposed as a criterion of the initiation and propagation of blisters. It provides the theory basis for further model experiment and simulation analysis.%为有效减少钢桥面环氧沥青铺装层出现鼓泡现象,采用现场调查、理论分析和数学建模的研究方法,系统地研究了鼓泡产生的原因和形成扩展机理。基于薄板理论,研究了鼓泡在竖向均布荷载作用下鼓泡挠度的变化规律。根据断裂力学中的能量原理,得到了鼓泡形成扩展过程中的能量关系,进而阐明了鼓泡形成扩展机理。研究结果表明:钢桥面环氧沥青铺装层鼓泡的形成扩展过程分为起裂、稳定扩展和失稳扩展3个阶段;鼓泡在外力作用下产生的挠度与鼓泡半径、铺装层厚度和弹性模量等因素有关,提出了以能量释放率为判定参数的扩展准则。

  14. Field Investigation of High Performance Pavements in Virginia

    OpenAIRE

    2005-01-01

    This study evaluated 18 pavement sections located in high-traffic highways in Virginia to find a premium pavement design with a life span of 40 years or more using current and past field experience. The selected pavement sections were thought to perform well. Eight flexible pavements, six composite pavements, two continuously reinforced concrete pavements, and two jointed plain concrete pavements were investigated. Field testing consisted of (1) falling weight deflectometer (FWD) testing to a...

  15. Web-based Courses for All Disciplines: How?

    Directory of Open Access Journals (Sweden)

    Karen S. Y. Lee

    2004-06-01

    Full Text Available World Wide Web functions offer flexible and powerful tools to online course instructorsm across disciplines. WebCT being one of the leading providers of integrated elearning systems, provides features that are conducive to learning and instruction.This article will discuss how to: 1. design and conduct WebCT courses across disciplines, 2. use the constructivist pedagogy of learning and teaching in WebCT courses, and 3. enhance the problem-based and self-regulated features of Web-based learning.The focal points of this article emphasize pedagogical reengineering for designing and conducting online courses that differ in delivery, reception, and learner participation from courses being offered via traditional instructional mode. Qualitative and innovative online instruction demands more complicated work, time, and patience than traditional mode of instructional delivery. Examples from two uniquely different disciplines are elaborated. Suggestions for creating and delivering online courses are also provided.

  16. 基于有限元方法的应力吸收层延缓反射裂缝分析%Analysis on the anti-crack Performance of Asphalt Pavement Based on Finite method

    Institute of Scientific and Technical Information of China (English)

    王鹏; 李昆; 黄卫东

    2011-01-01

    In China semi-rigid base course material accounts for 95% of subbase material in various grade highwayu at present. Though with the advantage of high strength plate and good freezing resistance, semi-rigid asphalt road is easy to crack because of shrink and low-temperature crack. Many measures have been taken including increasing the thickness of asphalt surface, using link structure or stress-absorbing interlayer and so on. But the focus of these measures are different and the function mechanisms are various.3-D Finite Element Modeling is used to model and analyze the typical road structure. Continuity and completely smooth state are considered. Under least favorable load condition, the influence of asphalt surface thickness on stress state of bottom of pavement is analyzed. Analysis shows that solely incerease the thickness of pavement is not the effective measure to postpone the reflective crack. The result also indicates the importance of adhesive property between layers. Though analysis also shows the rational thickness and modulus of stress-absorbing interlayer, and the adhesive strength is emphasized.%半刚性材料目前占到我国各等级公路路面基层材料用量的95%以上,半刚性基层沥青路面虽然具有板体强、抗冻性好等诸多优点,但是容易出现反射裂缝.国内外对半刚性基层沥青路面反射裂缝的防治包括增加沥青面层厚度、在基层与面层之间增加级配碎石层或应力吸收中间夹层等多种方式.这些措施的侧重各有不同,综合利用多种防裂措施与方法可以达到最佳的防裂措施.力图通过三维有限元建模分析,分别考虑层间连续和层间光滑两种状态,施加正荷载和偏荷载,用以分析典型路面结构中路面厚度对面层底部受力状态的影响,得出单纯增加路面厚度并非最佳防裂手段,并论证了保持良好层间粘结对与延缓反射裂缝的重要意义.并通过荷载作用下加铺应力吸收层的路面

  17. Laboratory Measurements of Particulate Matter Concentrations from Asphalt Pavement Abrasion

    Science.gov (United States)

    Fullová, Daša; Đurčanská, Daniela

    2016-12-01

    The issue of emissions from road traffic is compounded by the fact that the number of vehicles and driven kilometres increase each year. Road traffic is one of the main sources of particulate matter and traffic volume is still increasing and has unpleasant impact on longevity of the pavements and the environment. Vehicle motions cause mechanical wearing of the asphalt pavement surface - wearing course by vehicle tyres. The contribution deals with abrasion of bituminous wearing courses of pavements. The asphalt mixtures of wearing courses are compared in terms of mechanically separated particulate matter. The samples of asphalt mixtures were rutted in wheel tracking machine. The particulate matter measurements were performed in laboratory conditions. The experimental laboratory measurements make it possible to sample particulates without contamination from exhaust emissions, abraded particles from vehicles, resuspension of road dust and climate affects. The contribution offers partial results of measurements on six trial samples of asphalt mixtures with different composition. It presents particulate matter morphology and the comparison of rutted asphalt samples in terms of PM mass concentrations and chemical composition.

  18. Laboratory Measurements of Particulate Matter Concentrations from Asphalt Pavement Abrasion

    Directory of Open Access Journals (Sweden)

    Fullová Daša

    2016-12-01

    Full Text Available The issue of emissions from road traffic is compounded by the fact that the number of vehicles and driven kilometres increase each year. Road traffic is one of the main sources of particulate matter and traffic volume is still increasing and has unpleasant impact on longevity of the pavements and the environment. Vehicle motions cause mechanical wearing of the asphalt pavement surface - wearing course by vehicle tyres. The contribution deals with abrasion of bituminous wearing courses of pavements. The asphalt mixtures of wearing courses are compared in terms of mechanically separated particulate matter. The samples of asphalt mixtures were rutted in wheel tracking machine. The particulate matter measurements were performed in laboratory conditions. The experimental laboratory measurements make it possible to sample particulates without contamination from exhaust emissions, abraded particles from vehicles, resuspension of road dust and climate affects. The contribution offers partial results of measurements on six trial samples of asphalt mixtures with different composition. It presents particulate matter morphology and the comparison of rutted asphalt samples in terms of PM mass concentrations and chemical composition.

  19. 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.

  20. 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.

  1. Impact of the variation in dynamic vehicle load on flexible pavement responses

    Science.gov (United States)

    Ahsanuzzaman, Md

    The purpose of this research was to evaluate the dynamic variation in asphalt pavement critical responses due to dynamic tire load variations. An attempt was also made to develop generalized regression equations to predict the dynamic response variation in flexible pavement under various dynamic load conditions. The study used an extensive database of computed pavement response histories for five different types of sites (smooth, rough, medium rough, very rough and severely rough), two different asphalt pavement structures (thin and thick) at two temperatures (70 °F and 104 °F), subjected to a tandem axle dual tire at three speeds 25, 37 and 50 mph (40, 60 and 80 km/h). All pavement responses were determined using the 3D-Move Analysis program (Version 1.2) developed by University of Nevada, Reno. A new term called Dynamic Response Coefficient (DRC) was introduced in this study to address the variation in critical pavement responses due to dynamic loads as traditionally measured by the Dynamic Load Coefficient (DLC). While DLC represents the additional varying component of the tire load, DRC represents the additional varying component of the response value (standard deviation divided by mean response). In this study, DRC was compared with DLC for five different sites based on the roughness condition of the sites. Previous studies showed that DLC varies with vehicle speed and suspension types, and assumes a constant value for the whole pavement structure (lateral and vertical directions). On the other hand, in this study, DRC was found to be significantly varied with the asphalt pavement and function of pavement structure, road roughness conditions, temperatures, vehicle speeds, suspension types, and locations of the point of interest in the pavement. A major contribution of the study is that the variation of pavement responses due to dynamic load in a flexible pavement system can be predicted with generalized regression equations. Fitting parameters (R2) in the

  2. 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…

  3. 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…

  4. 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"…

  5. 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...

  6. 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…

  7. Wavelet-aided pavement distress image processing

    Science.gov (United States)

    Zhou, Jian; Huang, Peisen S.; Chiang, Fu-Pen

    2003-11-01

    A wavelet-based pavement distress detection and evaluation method is proposed. This method consists of two main parts, real-time processing for distress detection and offline processing for distress evaluation. The real-time processing part includes wavelet transform, distress detection and isolation, and image compression and noise reduction. When a pavement image is decomposed into different frequency subbands by wavelet transform, the distresses, which are usually irregular in shape, appear as high-amplitude wavelet coefficients in the high-frequency details subbands, while the background appears in the low-frequency approximation subband. Two statistical parameters, high-amplitude wavelet coefficient percentage (HAWCP) and high-frequency energy percentage (HFEP), are established and used as criteria for real-time distress detection and distress image isolation. For compression of isolated distress images, a modified EZW (Embedded Zerotrees of Wavelet coding) is developed, which can simultaneously compress the images and reduce the noise. The compressed data are saved to the hard drive for further analysis and evaluation. The offline processing includes distress classification, distress quantification, and reconstruction of the original image for distress segmentation, distress mapping, and maintenance decision-making. The compressed data are first loaded and decoded to obtain wavelet coefficients. Then Radon transform is then applied and the parameters related to the peaks in the Radon domain are used for distress classification. For distress quantification, a norm is defined that can be used as an index for evaluating the severity and extent of the distress. Compared to visual or manual inspection, the proposed method has the advantages of being objective, high-speed, safe, automated, and applicable to different types of pavements and distresses.

  8. Team-Based Learning in an Information Literacy Course

    Directory of Open Access Journals (Sweden)

    Trudi E. Jacobson

    2012-04-01

    Full Text Available The author implemented team-based learning (TBL in a credit-bearing information literacy course that meets a general education requirement at the University at Albany. TBL is a highly structured teaching method that includes a number of components not found in more traditional use of teams in the classroom. It required substantive changes in the course, which were notably repaid by the impact on student preparedness and engagement. The main elements of team-based learning are explained in the setting of this course.

  9. 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.

  10. 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.

  11. 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.

  12. 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…

  13. 基于衰变-Markov模型的沥青路面性能预测研究%Pavement Performance Prediction of HighWay Based on the Decay-Markov Prediction Model

    Institute of Scientific and Technical Information of China (English)

    武昭融; 李秀君; 李梦晨; 许光孝

    2016-01-01

    In the forecasting process of pavement performance indicators,there is usually the error fluctuation between the predicted value and measured value because of using different maintenance methods.In order to solve this problem,the prediction model based on the standard decay equation suggested by Professsor Sun Lijun of Tongji University was taken as the basis of prediction model for forecasting the performance variation of a certain number of sections on the Jiaxing part of S101 provincial road.According to the data about the pavement structure,its thickness and the volume of traffic,the weight values of pavement surface condition index (PCI)and riding quality index (RQI)which are the most dominant among the commonly used pavement quality indices (PQI)were predicted.The predicted data of decay equation were further revised by adopting the Markov transfer matrix method,which provides a reliable basis for the next maintenance decision.%为解决在路面使用性能各项指标的预测过程中,预测值与实测值间误差波动较大这一问题,采取同济大学孙立军教授提出的标准衰变方程作为预测模型的基础,充分调查浙江省 S101省道嘉兴段现有路况,根据收集的公路路面结构、厚度和交通量轴载数据等资料,对其沥青路面性能变化进行预测,即对路面损坏状况指数 PCI 和行驶质量指数 RQI 这两个在路面使用性能指数 PQI 中占较大权重的指标进行预测,继而采用 Markov 模型对其预测结果进行修正,建立与养护策略相对应的 Markov 转移矩阵而得到衰变-Markov 预测模型,为之后能准确掌握沥青路面使用性能变化趋势并得到合理的养护决策提供可靠依据。

  14. Hydrological Effect of Porous Pavement Based on SWMM%基于SWMM的透水性路面水文效应分析

    Institute of Scientific and Technical Information of China (English)

    梁春娣; 孙艳伟

    2012-01-01

    LID (Low Impact Development) measures of storm water management are meaningful in reducing urban flood peak discharge and improving eco-environment . The porous pavement makes runoff infiltrate into underground fast . Using it instead of common concrete pavement can reduce flood peak discharge in urban districts . By means of SWMM (Storm Water Management Model) , the paper simulates respectively the natural or regulated runoff processes of 2-year , 10-year and 100-year storm in following conditions : in pre-development of urbanization , ie in natural situation , in post-development without any regulation measure , ie only with common concrete pavement , and in the condition using porous pavement . The simulation results show that urbanization process increases flood peak dis-charge greatly and shortens the runoff duration time , the porous pavement has remarkable effect to reduce peak dis- charge and runoff volume.%LID(Low Impact Development,低影响发展)雨洪调控措施对消减城市洪峰流量,改善生态环境具有重要的意义。透水性路面通过快速入渗径流及减少区域不透水性比例,从而达到消减洪峰的作用。利用SWMM(Storm Warer Management Model,暴雨洪水管理模型)模拟软件,分别模拟了城市发展前(天然状态下)、发展后无调控措施(普通混凝土路面)及发展后利用透水性路面对2年、10年及100年设计暴雨进行调控的径流过程。模拟结果显示,城市化进程显著增大了洪峰流量,缩短了径流持续时间,透水性路面在消减洪峰流量和洪量方面具有显著的作用。

  15. CBR-Beta Design Procedure for Aggregate-Surfaced Airfield Pavements

    Science.gov (United States)

    2014-03-01

    ER D C/ G SL T R- 14 -6 CBR-Beta Design Procedure for Aggregate- Surfaced Airfield Pavements G eo te ch ni ca l a nd S tr uc tu re s...surfaces. The original flexible pavement design procedure of paved surfaces, which is based on the California Bearing Ratio (CBR) and the α-factor...Alpha-factor), was also extended and applied to the design and evaluation of aggregate-surfaced pavements . With the reformulation of the CBR-Alpha for

  16. 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…

  17. Variable Neighborhood Search Based Algorithm for University Course Timetabling Problem

    OpenAIRE

    Kralev, Velin; Kraleva, Radoslava

    2016-01-01

    In this paper a variable neighborhood search approach as a method for solving combinatoric optimization problems is presented. A variable neighborhood search based algorithm for solving the problem concerning the university course timetable design has been developed. This algorithm is used to solve the real problem regarding the university course timetable design. It is compared with other algorithms that are tested on the same sets of input data. The object and the methodology of study are p...

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

    OpenAIRE

    H. Russell Searight, PhD; Barbara K. Searight, PhD

    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" applications of class material. However, rather than traditional lecture-discussion, PBL encourages student autonomy in analyzing cases, with the instruc...

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

    OpenAIRE

    H. Russell Searight, PhD; Barbara K. Searight, PhD

    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" applications of class material. However, rather than traditional lecture-discussion, PBL encourages student autonomy in analyzing cases, with the i...

  20. Improving the distribution and reducing the magnitude of pavement damage

    Science.gov (United States)

    Barker, W. R.; Chou, U. T.

    1980-08-01

    In the analysis of flexible pavement, the layered elastic theory was used to compute the pavement response. For the rigid pavement, finite difference, layered elastic theory, and Westergard procedures were used to compute tensile stresses in concrete that formed the basis for predicting allowable stress repetitions. For flexible pavement, the only effective means to reduce pavement damage was to modify the wheel assembly to reduce stress or strain at the critical locations in the pavement systems. The most effective modification would be to increase the spacing between duals. For rigid pavements, the edge effect was critical, thus suggesting that modifications to shift the loading away from the pavement edge would be effective.

  1. Investigation of perpetual pavement using finite element modelling

    Directory of Open Access Journals (Sweden)

    Monireh Zokaei

    2016-06-01

    Full Text Available With considering numerous failures which exist in flexible pavements, a huge amount of money is spending on treatment and reconstructing pavements. Many researches have been performed to with improving pavement quality, increased the performance and pavements life. One type of long lasting pavements is perpetual pavement. In this research ABAQUS software is used to simulate pavement. . Materials are modelled as visco-elastic type and loading wheel is assumed to be moving. After gaining results, the effects of different parameters on pavements function is assessed. Modelling movements of loading wheel is very effective in viscoelastic condition, increase more accuracy of the finite-element model.

  2. Removable Urban Pavements: An innovative, sustainable technology

    OpenAIRE

    2012-01-01

    Removable Urban Pavements: An innovative, sustainable technology By definition, a Removable Urban Pavement (RUP) can be quickly opened and closed, using lightweight equipment, for easy access to underground networks. While no such pavement appears to have ever been constructed, the premises of the concept can be found in certain military paths or industrial soils. A survey conducted among French municipal authorities has revealed the potential benefit of the RUP concept in decreasing the publ...

  3. Improving Data Quality for Pavement Management System

    OpenAIRE

    2015-01-01

    The Metropolitan Transportation Commission (MTC) has developed a pavement management StreetSaver program with more than 400 users in the United States. MTC uses the program to evaluate street and road condition and perform maintenance needs assessments for the 109 cities and counties in the San Francisco Bay Area. Quality pavement condition survey data is a critical component of a pavement management system. MTC has augmented a new quality acceptance (QA) program as part of its Quality Data M...

  4. 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.

  5. 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.

  6. 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.

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

    Science.gov (United States)

    Rajbongshi, Pabitra; Thongram, Sonika

    2016-09-01

    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.

  8. 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.

  9. Nutrient infiltrate concentrations from three permeable pavement types.

    Science.gov (United States)

    Brown, Robert A; Borst, Michael

    2015-12-01

    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 parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m(2), lined sections that direct all infiltrate into 5.7-m(3) tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP

  10. Problem-based learning in a health sciences librarianship course.

    Science.gov (United States)

    Dimitroff, A; Ancona, A M; Beman, S B; Dodge, A M; Hutchinson, K L; LaBonte, M J; Mays, T L; Simon, D T

    1998-07-01

    Problem-based learning (PBL) has been adopted by many medical schools in North America. Because problem solving, information seeking, and lifelong learning skills are central to the PBL curriculum, health sciences librarians have been actively involved in the PBL process at these medical schools. The introduction of PBL in a library and information science curriculum may be appropriate to consider at this time. PBL techniques have been incorporated into a health sciences librarianship course at the School of Library and Information Science (LIS) at the University of Wisconsin-Milwaukee to explore the use of this method in an advanced Library and Information Science course. After completion of the course, the use of PBL has been evaluated by the students and the instructor. The modified PBL course design is presented and the perceptions of the students and the instructor are discussed.

  11. Transitional clerkship: an experiential course based on workplace learning theory.

    Science.gov (United States)

    Chittenden, Eva H; Henry, Duncan; Saxena, Varun; Loeser, Helen; O'Sullivan, Patricia S

    2009-07-01

    Starting clerkships is anxiety provoking for medical students. To ease the transition from preclerkship to clerkship curricula, schools offer classroom-based courses which may not be the best model for preparing learners. Drawing from workplace learning theory, the authors developed a seven-day transitional clerkship (TC) in 2007 at the University of California, San Francisco School of Medicine in which students spent half of the course in the hospital, learning routines and logistics of the wards along with their roles and responsibilities as members of ward teams. Twice, they admitted and followed a patient into the next day as part of a shadow team that had no patient-care responsibilities. Dedicated preceptors gave feedback on oral presentations and patient write-ups. Satisfaction with the TC was higher than with the previous year's classroom-based course. TC students felt clearer about their roles and more confident in their abilities as third-year students compared with previous students. TC students continued to rate the transitional course highly after their first clinical rotation. Preceptors were enthusiastic about the course and expressed willingness to commit to future TC preceptorships. The transitional course models an approach to translating workplace learning theory into practice and demonstrates improved satisfaction, better understanding of roles, and increased confidence among new third-year students.

  12. 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.

  13. 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…

  14. 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

    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...... 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 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...

  15. Enhancing pavements for thermal applications

    OpenAIRE

    Keikhaei Dehdezi, Pejman

    2012-01-01

    Renewable energy combined with energy efficiency can offer a viable and influential solution to minimise the harmful consequences of both fossil fuel depletion and increases in the cost of power generation. However, in most cases renewable energy technologies require high initial investments that may deter potential users. Pavement Energy Systems (PES) potentially offer a low-cost solution to sustainable and clean energy generation by utilising the thermo-physical properties and design featur...

  16. Integration of Task-Based Approaches in a TESOL Course

    Science.gov (United States)

    Chien, Chin-Wen

    2014-01-01

    Under task-based language teaching (TBLT), language learners engage in purposeful, problem-oriented, and outcome-driven tasks that are comparable to real-world activities. This qualitative case study discusses the integration of a task-based approach into a TESOL course in a language teacher education program in Taiwan with regard to 39…

  17. Full-Scale Accelerated Pavement Testing of Warm-Mix Asphalt (WMA) for Airfield Pavements

    Science.gov (United States)

    2014-01-01

    ER D C/ G SL T R -1 4 -3 Full-Scale Accelerated Pavement Testing of Warm-Mix Asphalt (WMA) for Airfield Pavements G eo te ch n ic al...2014 Full-Scale Accelerated Pavement Testing of Warm-Mix Asphalt (WMA) for Airfield Pavements Mariely Mejías-Santiago, Jesse D. Doyle, and John F... asphalt (WMA) mixtures designed for airfield pavements. Three WMA mixtures were evaluated and compared to a control hot-mix asphalt (HMA) mixture. Data

  18. 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.

  19. 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.

  20. 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.

  1. DEVELOPING WEB-BASED PERFORMANCE ASSESSMENT IN INTEGRATED SCIENCE COURSE

    Directory of Open Access Journals (Sweden)

    S. Wahyuni

    2015-04-01

    Full Text Available This research aims to develop a web-based performance assessment in Integrated Science course. The research was Research and Development (R & D. The expert validation of developed products resulted the average percentage of 3.88 for content category, 3.94 for format category, and 3.78 for language category. Meanwhile, critical thinking skill aspect resulted percentage of 92.20 basic clarification indicators, 90.05 for basic for the decision category, and 94.67 for inference category. Students also responded positively to web-based performance assessment in Integrated Science course.

  2. Modelling of pavement materials on steel decks using the five-point bending test: Thermo mechanical evolution and fatigue damage

    Science.gov (United States)

    Arnaud, L.; Houel, A.

    2010-06-01

    This paper deals with the modelling of wearing courses on steel orthotropic decks such as the Millau viaduct in France. This is of great importance when dealing with durability: due to the softness of such a support, the pavement is subjected to considerable strains that may generate top-down cracks in the layer at right angles of the orthotropic plate stiffeners and shear cracks at the interface between pavement and steel. Therefore, a five-point bending fatigue test was developed and improved since 2003 at the ENTPE laboratory, to test different asphalt concrete mixes. This study aims at modelling the mechanical behavior of the wearing course throughout the fatigue test by a finite element method (Comsol Multiphysics software). Each material - steel, sealing sheet, asphalt concrete layer - is considered and modelled. The modelling of asphalt concrete is complex since it is a heterogeneous material, a viscoelastic medium and it thermosensitive. The actual characteristics of the asphalt concrete (thermo physical parameter and viscoelastic complex modulus) are determined experimentally on cylindrical cores. Moreover, a damage law based on Miner's damage is included in the model. The modelling of the fatigue test leads to encouraging results. Finally, results from the model are compared to the experimental data obtained from the five-point bending fatigue test device. The experimental data are very consistent with the numerical simulation.

  3. 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

  4. Evaluation of Precast Panels for Airfield Pavement Repair. Phase 2: Results of Accelerated Pavement Testing

    Science.gov (United States)

    2013-09-01

    emergency or contingency airfield opera - tions. This report presents the results of accelerated pavement testing including the passes-to-failure, surface...9-in.-diam Geokon® earth pressure cells (EPC) capable of measuring up to 200 psi that were installed at the base-PCC interface at 10 locations as...Center deflections. 0 10 20 30 40 50 60 70 80 90 100 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 N or m al ize d  De fle ct io n,  m ils

  5. A community-based, interdisciplinary rehabilitation engineering course.

    Science.gov (United States)

    Lundy, Mary; Aceros, Juan

    2016-08-01

    A novel, community-based course was created through collaboration between the School of Engineering and the Physical Therapy program at the University of North Florida. This course offers a hands-on, interdisciplinary training experience for undergraduate engineering students through team-based design projects where engineering students are partnered with physical therapy students. Students learn the process of design, fabrication and testing of low-tech and high-tech rehabilitation technology for children with disabilities, and are exposed to a clinical experience under the guidance of licensed therapists. This course was taught in two consecutive years and pre-test/post-test data evaluating the impact of this interprofessional education experience on the students is presented using the Public Service Motivation Scale, Civic Actions Scale, Civic Attitudes Scale, and the Interprofessional Socialization and Valuing Scale.

  6. 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

  7. Illumination system design in a project-based course

    Science.gov (United States)

    Koshel, R. John; Abraham, Vineeth; Kim, Joshua; Liu, Ron; Richardson, Scott; Namnabat, Soha; Czajkowski, Amber; Abd El-Maksoud, Rania H.; Irvin, Ryan; Nakazawa, Takeshi; Kudenov, Michael; Dawsey, Martha; de Leon, Erich; Wang, Lirong; Crabtree, Karlton; Orr, R. M.; Primeau, Brian; Kim, Yullin

    2009-08-01

    This past spring a new for-credit course on illumination engineering was offered at the College of Optical Sciences at The University of Arizona. This course was project based such that the students could take a concept to conclusion. The main goal of the course was to learn how to use optical design and analysis software while applying principles of optics to the design of their optical systems. Projects included source modeling, displays, daylighting, light pollution, faceted reflectors, and stray light analysis. In conjunction with the course was a weekly lecture that provided information about various aspects of the field of illumination, including units, étendue, optimization, solid-state lighting, tolerancing, litappearance modeling, and fabrication of optics. These lectures harped on the important points of conservation of étendue, source modeling and tolerancing, and that no optic can be made perfectly. Based on student reviews, future versions of this course will include more hands-on demos of illumination components and assignments.

  8. 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…

  9. 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.…

  10. 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…

  11. 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.

  12. An Event Grouping Based Algorithm for University Course Timetabling Problem

    OpenAIRE

    Kralev, Velin; Kraleva, Radoslava; Yurukov, Borislav

    2016-01-01

    This paper presents the study of an event grouping based algorithm for a university course timetabling problem. Several publications which discuss the problem and some approaches for its solution are analyzed. The grouping of events in groups with an equal number of events in each group is not applicable to all input data sets. For this reason, a universal approach to all possible groupings of events in commensurate in size groups is proposed here. Also, an implementation of an algorithm base...

  13. Consensus-Based Course Design and Implementation of Constructive Alignment Theory in a Power System Analysis Course

    Science.gov (United States)

    Vanfretti, Luigi; Farrokhabadi, Mostafa

    2015-01-01

    This article presents the implementation of the constructive alignment theory (CAT) in a power system analysis course through a consensus-based course design process. The consensus-based design process involves both the instructor and graduate-level students and it aims to develop the CAT framework in a holistic manner with the goal of including…

  14. Performance Prediction of the NCAT Test Track Pavements Using Mechanistic Models

    Science.gov (United States)

    LaCroix, Andrew Thomas

    In the pavement industry in the United States of America, there is an increasing desire to improve the pavement construction quality and life for new and rehabilitated pavements. In order to improve the quality of the pavements, the Federal Highway Administration (FHWA) has pursued a performance-related specification (PRS) for over 20 years. The goal of PRS is to provide material and construction (M/C) properties that correlate well with pavement performance. In order to improve upon the PRS projects developed in WesTrack (NCHRP 9-20) and the MEPDG-based PRS (NCHRP 9-22), a set of PRS tests and models are proposed to provide a critical link between pavement performance and M/C properties. The PRS testing is done using the asphalt mixture performance tester (AMPT). The proposed PRS focuses on rutting and fatigue cracking of asphalt mixtures. The mixtures are characterized for their stiffness, fatigue behavior, and rutting resistance using a dynamic modulus (|E*|) test, a fatigue test, and a triaxial stress sweep (TSS) test, respectively. Information from the fatigue test characterizes the simplified viscoelastic continuum damage (S-VECD) model. Once the stiffness is reduced to a certain level, the material develops macro-cracks and fails. The TSS test is used to characterize a viscoplastic (VP) model. The VP model allows the prediction of the rut depth beneath the center of the wheel. The VECD and VP models are used within a layered viscoelastic (LVE) pavement model to predict fatigue and rutting performance of pavements. The PRS is evaluated by comparing the predictions to the field performance at the NCAT pavement test track in Opelika, Alabama. The test track sections evaluated are part of the 2009 test cycle group experiment, which focused on WMA, high RAP (50%), and a combination of both. The fatigue evaluation shows that all sections would last at least 18 years at the same traffic rate. The sections do not show any cracking, suggesting the sections are well

  15. Environmental history recorded in aeolian deposits under stone pavements, Mojave Desert, USA

    Science.gov (United States)

    Dietze, Michael; Dietze, Elisabeth; Lomax, Johanna; Fuchs, Markus; Kleber, Arno; Wells, Stephen G.

    2016-01-01

    Reconstructing the evolution of arid landscapes is challenged by limited availability of appropriate environmental archives. A widespread surface feature - stone pavement - traps aeolian fines and forms a special accretionary archive. Seven stone pavement-covered sections on basalt flows in the eastern Mojave Desert are condensed into a composite section, comprising five sedimentological units supported by an OSL-based chronology. Three of the units are of accretionary nature and each is covered by a stone pavement. They were deposited > 50.9-36.6 ka, < 36.6-14.2 ka and < 14.2 ka, and they are intimately coupled with the history of nearby Lake Mojave, which advances the current understanding of regional aeolian activity. End-member modeling analysis of grain-size distributions yielded seven sediment transport regimes. The accretionary system operates in two modes: A) episodic formation of a stone pavement by lateral processes once a vesicular horizon has formed on a barren surface; and B) accretion of dust and eventual burial of the clast layer. These findings improve current concepts about stone pavement evolution and their environmental proxy function in arid landscapes. Stone pavement-covered accretionary deposits are a new key archive that allows quantifying the relative importance of dust accretion, slope processes, soil formation and vegetation cover.

  16. 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.

  17. Effective flow resistivity of highway pavements.

    Science.gov (United States)

    Rochat, Judith L; Read, David R

    2013-12-01

    In the case of highway traffic noise, propagating sound is influenced by the ground over which it travels, whether it is the pavement itself or the ground between the highway and nearby communities. Properly accounting for ground type in modeling can increase accuracy in noise impact determinations and noise abatement design. Pavement-specific effective flow resistivity values are being investigated for inclusion in the Federal Highway Administration Traffic Noise Model, which uses these values in the sound propagation algorithms and currently applies a single effective flow resistivity value to all pavement. Pavement-specific effective flow resistivity values were obtained by applying a modified version of the American National Standards Institute S1.18 standard. The data analysis process was tailored to allow for increased sensitivity and extraction of effective flow resistivity values for a broad range of pavements (sound absorptive to reflective). For porous pavements (sound absorptive), it was determined that examination of the measured data can reveal influence from an underlying structure. Use of such techniques can aid in the design of quieter pavements.

  18. 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.

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

    Directory of Open Access Journals (Sweden)

    H. Russell Searight, PhD

    2009-01-01

    Full Text Available 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" applications of class material. However, rather than traditional lecture-discussion, PBL encourages student autonomy in analyzing cases, with the instructor serving initially as a structuring facilitator before gradually becoming less active as students take more responsibility for their learning. As students proceed through each case, they address four dimensions: What they know, what they want to know, possible causal hypotheses, and questions that can be answered through library research. The PBL cases referred to herein were developed and employed for an undergraduate psychology course, "Psychology of the Exceptional Child." Students completing this course included psychology, special education, and human service majors and have positively evaluated this technique as a teaching tool.

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

    Directory of Open Access Journals (Sweden)

    H. Russell Searight, PhD

    2009-08-01

    Full Text Available 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" applications of class material. However, rather than traditional lecture-discussion, PBL encourages student autonomy in analyzing cases, with the instructor serving initially as a structuring facilitator before gradually becoming less active as students take more responsibility for their learning. As students proceed through each case, they address four dimensions: What they know, what they want to know, possible causal hypotheses, and questions that can be answered through library research. The PBL cases referred to herein were developed and employed for an undergraduate psychology course, "Psychology of the Exceptional Child." Students completing this course included psychology, special education, and human service majors and have positively evaluated this technique as a teaching tool.

  1. Asphalt pavement surface 3D data acquisition system based on line-structure light%基于线结构光的沥青路面三维数据采集系统

    Institute of Scientific and Technical Information of China (English)

    孙朝云; 呼延菊; 李伟; 魏子尧; 刘祝

    2016-01-01

    To solve the problem of poor real-time,low accuracy of current asphalt pavement surface 3D data acquisition system,which can not provide 3D pavement data comprehensively,this paper studied an asphalt pavement 3D data acquisition system based on line-structure light.The system was a three-dimensional equipment with optical and electrical integration and automation,which was designed for domestic road three-dimensional information detection.It could realize data collection,analysis,processing,3D display for asphalt pavement surface topography.The system used infrared laser light source,planar array CCD camera and digital image detection technology.This system computed the 3D depth information based on laser triangulation algorithm,finished 3D reconstruction of road surface morphology by use of MATLAB software to obtain 3D display after reconstruction,and did quantitative analysis of detection results.Based on modular design,this system mainly consisted of power supply module,salve computer control module,counting trigger module,laser triangulation detection module,GPS module and data processing module.The 3D data of asphalt pavement were obtained through testing software's driving hardware modules.The results show that modular design improves anti-interference,making the system structure simple and clear,and relieve from the complex wires.It is convenient for debugging,maintenance,shorten development cycle,and the cost for development and maintenance is also reduced.The results also show that the system can not only meet the requirements of asphalt pavement 3D data acquisition and the requirements of real-time detection,but also provide vivid and visualized 3D visual topography.17 figs,21 refs.%针对目前沥青路面表面形貌三维数据采集实时性差、精确度低,难以准确全面地提供路面三维构造形态的问题,研究了基于线结构光的沥青路面表面形貌三维数据采集系统.该系统是针对中国道路三维信息检测要求

  2. 基于桥面铺装技术的城市高架桥梁设计研究%Urban Elevated Bridge Design Based on Deck Pavement Technology

    Institute of Scientific and Technical Information of China (English)

    宋殿峰

    2014-01-01

    This article expounds the deck pavement techn-ology of urban elevated bridge and points out the existing problems, and puts forward pavement construction, joints treatment and other technical processing measures through analyzes the deck pavement technology of urban elevated bridge.%本文对城市高架桥梁桥面铺装工艺进行了阐述,指出面铺装存在的问题,通过对高架桥桥面铺装技术的分析,提出了摊铺施工、接缝处理等技术处理举措。

  3. On-road Bicycle Pavement Markings

    Data.gov (United States)

    Allegheny County / City of Pittsburgh / Western PA Regional Data Center — A mile by mile breakdown of the on-street bicycle pavement markings installed within the City of Pittsburgh. These include bike lanes, shared lane markings...

  4. "Comparison of some Structural Analyses Methods used for the Test Pavement in the Danish Road Testing Machine

    DEFF Research Database (Denmark)

    Baltzer, S.; Zhang, W.; Macdonald, R.;

    1998-01-01

    A flexible test pavement, instrumented to measure stresses and strains in the three primary axes with the upper 400 mm of the subgrade, has been constructed and load tested in the Danish Road Testing Machine (RTM). One objective of this research, which is part of the International Pavement Subgrade...... methods used for the RTM test pavement with data from FWD testing undertaken after the construction and loading programmes. Multilayer linear elastic forward and backcalculation methods, a finite element program and MS Excel spreadsheet based methods are compared....

  5. Development of a Full-Depth Wheel Tracking Test for Asphalt Pavement Structure: Methods and Performance Evaluation

    Directory of Open Access Journals (Sweden)

    Hui Wang

    2016-01-01

    Full Text Available The rutting performance of asphalt pavement structure relies on the high temperature properties of asphalt mixture as well as the pavement structure and thickness. In order to investigate the influence of the structure and thickness, a full-depth wheel tracking test is developed in this research by improving the conventional wheel tracking test apparatus. The newly proposed test method is capable of varying its load speed and load size, controlling its specimen temperature gradient, and simulating the support conditions of actual asphalt pavement. The full-depth wheel tracking test based rutting performance evaluation of different asphalt pavement structures indicates that it is not reasonable to explain the rutting performance of asphalt pavement structure from the point of view of single-layer asphalt mixture rutting performance. The developed full-depth wheel tracking test can be used to distinguish rutting performance of different asphalt pavement structures, and two of five typical asphalt pavement structures commonly used in Shanxi Province were suggested for use in practical engineering.

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

    Science.gov (United States)

    Van Metre, P.C.; Mahler, B.J.; Wilson, J.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 ?? PAH concentrations in dust from sealcoated and unsealcoated pavement are 2200 and 27 mg/kg, respectively. For three western cities, median ?? PAH 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.

  7. 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.

  8. Mechanical properties of full-depth cold regenerated base mixture from old asphalt pavement%旧沥青路面全深式冷再生基层材料力学性能

    Institute of Scientific and Technical Information of China (English)

    吴文飞; 何锐; 陈华鑫; 武书华

    2016-01-01

    为研究应用旧沥青路面材料冷再生基层的混合料力学性能,回收原沥青路面面层旧料和基层旧料,制备沥青路面全深式冷再生基层材料,结合现场沥青面层及铣刨深度测试冷再生材料级配,测试冷再生基层材料的7 d无侧限抗压强度、90 d劈裂强度和90 d回弹模量,并观察其SEM微观形貌图。结果表明:水泥用量较少时7 d无侧限抗压强度、90 d劈裂强度和90 d回弹模量均随水泥剂量的增加快速增长,但是增长趋势逐渐变缓;较少的沥青旧料对再生基层力学性能是有利的,但是过多的沥青旧料则会产生较大的负面影响;当面层旧料的油石比较小时,水泥水化物取向结晶能刺破沥青膜层,直接与裹附在沥青内部的集料接触,形成较强的界面,这样能有效缓解沥青对强度的负面影响。进而建议低等级公路的中、轻型交通等级水泥剂量在5%~7%,其他类型公路则在提高水泥剂量的同时需要改善旧料级配;油石比小的旧沥青路面改造更适合推行全深式冷再生基层技术。%In order to analyze the mechanical properties of cold regenerated base mixture from old asphalt pavement, the old material of original asphalt pavement and base was recycled to prepare the full depth base mixture. Combined with on-site asphalt surface layer and milling depth, the grada-tion of cold regenerated base mixture was analyzed. The 7 d unconfined compressive strength, 90 d splitting strength and 90 d modulus of resilience of the mixture were tested, and the SEM morphology of the mixture was observed. The results show that, when less amount of cement content was used, the 7 d unconfined compressive strength, 90 d splitting strength and 90 d resilient modulus of the mixture increase rapidly with the growth of the cement dosage, while the growth is becoming slowly;that it would benefit the mechanical properties of reclaimed base if a small quantity

  9. A Semantics-Based Information Distribution Framework for Large Web-Based Course Forum System

    Science.gov (United States)

    Chim, Hung; Deng, Xiaotie

    2008-01-01

    We propose a novel data distribution framework for developing a large Web-based course forum system. In the distributed architectural design, each forum server is fully equipped with the ability to support some course forums independently. The forum servers collaborating with each other constitute the whole forum system. Therefore, the workload of…

  10. 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,…

  11. 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.

  12. Theme-Based Courses Foster Student Learning and Promote Comfort with Learning New Material

    Science.gov (United States)

    Tessier, Lisa; Tessier, Jack

    2015-01-01

    In this article, we review the literature about theme-based teaching, then report quantitative and qualitative results from surveys from three different courses: one section of a 100-level in-person art course; five sections of 300-level on-line art courses; and one section of a 100-level in-person biology course at SUNY Delhi with applied themes…

  13. The Use of a Web-Based Course Management System: Causes and Performance Effects

    Science.gov (United States)

    Ring, J. Kirk; Kellermanns, Franz W.; Barnett, Tim; Pearson, Allison W.; Pearson, Rodney A.

    2013-01-01

    This article reports the results of two studies that examined (a) students' intentions to use a web-based course management system, (b) their actual use of a course management system, and (c) the effect of their use of a course management system on classroom performance. We found that students' attitudes toward the course management…

  14. 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.

  15. 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....... From ITC-2007, many researchers have developed advanced models and methods to solve CB-CTT. This survey is devoted to review the main works on the topic, with focus on mathematical models, lower bounds, and exact and heuristic algorithms. Besides giving an overview of these approaches, we highlight...

  16. 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.

  17. 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.

  18. 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…

  19. 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…

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Discrete element modelling of permanent pavement deformation in granular materials

    OpenAIRE

    Cai, Wei

    2015-01-01

    The permanent deformation of a pavement due to vehicle load is one of the important factors affecting the design life as well as the maintenance cost of a pavement. For the purpose of obtaining a cost-effective design, it is advisable to predict the traffic-loadinduced permanent pavement deformation. The permanent deformation in pavements (i.e. rutting) can be classified into three categories, including the wearing of the asphalt layers, compaction, and shear deformations. In the present stud...

  5. 沥青面层结构参数对倒装路面结构非线性响应分析%Analysis of Nonlinear Response of Asphalt Surface Structural Parameters on Inverted Pavement Structure

    Institute of Scientific and Technical Information of China (English)

    胡海学; 肖庆一; 王志辉; 侯子义

    2011-01-01

    级配碎石过渡层能有效防止或减少半刚性基层反射裂缝,改善沥青路面排水条件,但级配碎石模量低,具有非线性应力应变特性,将其作为过渡层置于沥青面层与半刚性基层之间,会改变原路面结构应力状况.通过使用非线性路面设计程序,从沥青面层厚度、模量两个路面结构参数分析路表弯沉值、面层及半刚性基层层底拉应力、土基顶面压应变等控制指标.归纳总结沥青面层厚度以及回弹模量变化对路面各个结构层的拉、压、剪切等力学响应规律,对倒装结构组合设计具有重要的参考价值.%The graded aggregate transition layer can effectively prevent or reduce reflective cracks in the semi-rigid base course and improve the drainage conditions of asphalt road surface, but, graded aggregate has a low modulus and a nonlinear stress-strain behavior. If such graded aggregate is used as a transition layer between the asphalt surface layer and the semi-rigid base, it may change the stress of original pavement structure. By using pavement design software based on the nonlinear theory, surface deflection, tensile stress in underside of surface layer and semi-rigid base course, compressive strain on top of subgrade and other control indicators are analyzed from two structural parameters of thickness and modulus of asphalt surface layer. The law of mechanical response of the variation of thickness and modulus of resilience of asphalt pavement on the tensile, compressive and shear stress in various structural layers of road pavement is analyzed and summarized, providing important reference for the combined design of inverted pavement structures.

  6. 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

  7. Research on construction technology for orthotropic steel deck pavement of Haihe River Chunyi Bridge

    Science.gov (United States)

    Xue, Y. C.; Qian, Z. D.; Zhang, M.

    2017-01-01

    In order to ensure the good service quality of orthotropic steel deck pavement of Haihe River Chunyi Bridge in Tianjin, and to reduce the occurrence of pavement diseases like lateral and longitudinal cracks, the key working procedures such as steel deck cleaning, anticorrosive coating, bonding layer spraying, seam cutting, epoxy asphalt concrete’s mixing, transportation, paving and compaction were studied. The study was based on the main features of epoxy asphalt concrete which is the pavement materials of Haihe River Chunyi Bridge, and combined with the basic characteristics and construction conditions of Haihe River Chunyi Bridge. Furthermore, some processing measures like controlling time and temperature, continuous paving with two pavers, lateral feeding, and improving the compaction method were proposed. The project example shows that the processing measures can effectively solve the technical difficulties in the construction of orthotropic steel deck pavement of Haihe River Chunyi Bridge, can greatly improve the construction speed and quality, and can provide reference for the same kinds of orthotropic steel deck pavement construction.

  8. 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.

  9. 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)

  10. 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

  11. Acquisition System for Three-Dimensional Surface Texture of Asphalt Pavement Based on Digital Image Processing%基于数字图像技术的沥青路表面三维构造获取系统

    Institute of Scientific and Technical Information of China (English)

    刘亚敏; 韩森; 徐鸥明

    2014-01-01

    In order to make an objective and true evaluation on three-dimension surface texture of asphalt pavement,an acquisition system for surface three-dimensional texture of asphalt pavement was developed based on the digital image processing. First,the classical Lambertian diffuse model was used to obtain three red,green,blue images. Then photometric stereo method was employed to calculated the surface gradients in x and y directions with the reflection intensity of three images. Finally the Frankot-Chellappa global integration algorithm was applied to making the Fourier transformation of the gradients. Thus the heights were obtained and the surface texture was reconstructed. The results indicate that the accuracy of height value obtained by the acquisition system is 0. 000 1 mm,which meets the requirement for analysis of texture depth;the correlation coefficient between the results of this system and the traditional sand patch test is 0 . 887 5 ,which demonstrates that this acquisition system is practical.%为了客观、真实地评价沥青路表面三维构造,利用数字图像技术研制了一种沥青路表面三维构造获取系统.首先基于经典的漫反射模型---the Lambertian Model,获取3张红、蓝、绿二维图像;然后根据光度立体法,利用3张图像的反射光强度计算其x、y方向上的梯度数据;最后借助Frankot-Chellappa全局积分算法将梯度数据进行傅立叶变换,计算得到高度值,实现路表面构造的三维重建.研究结果表明,该系统获取的高度值精度达到0.0001 mm,满足分析构造深度的要求;与传统方法---铺砂法的测试结果相关系数R=0.8875,相关性较好,证明了该系统应用的可行性.

  12. 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…

  13. Building a Sense of Community for Text-Based Computer-Mediated Communication Courses

    Science.gov (United States)

    Yang, Harrison Hao; Liu, Yuliang

    2008-01-01

    Building a strong sense of community in text-based computer-mediated communication courses can be a challenge to instructors. This article presents how a sound practical approach called STEP is implemented into one text-based fully online course and one hybrid course at a university in the northeastern region of the United States. Students'…

  14. Combination of the Research-Based Learning Method with the Modern Physics Experiment Course Teaching

    Science.gov (United States)

    Liu, Xiaolai; Li, Qinghuai

    2011-01-01

    It has been the hotspot to reconstruct the education course based on the research-based learning in the course reform in many countries in recent years. The new course standard of China insists that the teaching is the interactive process that teachers and students communicate and develop together. In the teaching, the relationship between…

  15. Curriculum Guidelines for a Distance Education Course in Urban Agriculture Based on an Eclectic Model.

    Science.gov (United States)

    Gaum, Wilma G.; van Rooyen, Hugo G.

    1997-01-01

    Describes research to develop curriculum guidelines for a distance education course in urban agriculture. The course, designed to train the teacher, is based on an eclectic curriculum design model. The course is aimed at the socioeconomic empowerment of urban farmers and is based on sustainable ecological-agricultural principles, an…

  16. Spills on Flat Inclined Pavements

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Carver S.; Keller, Jason M.; Hylden, Jeff L.

    2004-03-01

    This report describes the general spill phenomenology for liquid spills occurring on relatively impermeable surfaces such as concrete or asphalt pavement and the development and application of a model to describe the time evolution of such spills. The discussion assumes evaporation and degradation are negligible and a homogeneous surface. In such an instance, the inherent interfacial properties determine the spatial extent of liquid spreading with the initial flow being controlled by the release rate of the spill and by the liquids resistance to flow as characterized by its viscosity. A variety of spill scenarios were simulated and successful implementation of the model was achieved. A linear relationship between spill area and spill volume was confirmed. The simulations showed spill rate had little effect on the final spill area. Slope had an insignificant effect on the final spill area, but did modify spill shape considerably. However, a fluid sink on the edge of the simulation domain, representing a storm drain, resulted in a substantial decrease in spill area. A bona fide effort to determine the accuracy of the model and its calculations remain, but comparison against observations from a simple experiment showed the model to correctly determine the spill area and general shape under the conditions considered. Further model verification in the form of comparison against small scale spill experiments are needed to confirm the models validity.

  17. Effectiveness of inquiry-based learning in an undergraduate exercise physiology course

    DEFF Research Database (Denmark)

    Nybo, Lars; May, Michael

    2015-01-01

    (individual subject-specific tests and group interviews) were performed for a laboratory course in cardiorespiratory exercise physiology that was conducted in one year with a traditional step-by-step guided manual (traditional course) and the next year completed with an inquiry-based structure (I-based course......). The I-based course was a guided inquiry course where students had to design the experimental protocol and conduct their own study on the basis of certain predefined criteria (i.e., they should evaluate respiratory responses to submaximal and maximal exercise and provide indirect and direct measures...... of aerobic exercise capacity). The results indicated that the overall time spent on the experimental course as well as self-evaluated learning outcomes were similar across groups. However, students in the I-based course used more time in preparation (102 ± 5 min) than students in the traditional course (42...

  18. Modelling of pavement materials on steel decks using the fivepoint bending test: thermo mechanical evolution and fatigue damage

    OpenAIRE

    Arnaud, Laurent; Houel, Adrien

    2010-01-01

    This paper deals with the modelling of wearing courses on steel orthotropic decks such as the Millau viaduct in France. This is of great importance when dealing with durability: due to the softness of such a support, the pavement is subjected to considerable strains that may generate top-down cracks in the layer at right angles of the orthotropic plate stiffeners and shear cracks at the interface between pavement and steel. Therefore, a five-point bending fatigue test was developed and improv...

  19. 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。

  20. 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.

  1. Computer Based Collaborative Problem Solving for Introductory Courses in Physics

    Science.gov (United States)

    Ilie, Carolina; Lee, Kevin

    2010-03-01

    We discuss collaborative problem solving computer-based recitation style. The course is designed by Lee [1], and the idea was proposed before by Christian, Belloni and Titus [2,3]. The students find the problems on a web-page containing simulations (physlets) and they write the solutions on an accompanying worksheet after discussing it with a classmate. Physlets have the advantage of being much more like real-world problems than textbook problems. We also compare two protocols for web-based instruction using simulations in an introductory physics class [1]. The inquiry protocol allowed students to control input parameters while the worked example protocol did not. We will discuss which of the two methods is more efficient in relation to Scientific Discovery Learning and Cognitive Load Theory. 1. Lee, Kevin M., Nicoll, Gayle and Brooks, Dave W. (2004). ``A Comparison of Inquiry and Worked Example Web-Based Instruction Using Physlets'', Journal of Science Education and Technology 13, No. 1: 81-88. 2. Christian, W., and Belloni, M. (2001). Physlets: Teaching Physics With Interactive Curricular Material, Prentice Hall, Englewood Cliffs, NJ. 3. Christian,W., and Titus,A. (1998). ``Developing web-based curricula using Java Physlets.'' Computers in Physics 12: 227--232.

  2. 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.

  3. 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.

  4. 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

    OpenAIRE

    César Augusto Hidalgo Montoya; Carlos Arturo Pandales; Boris Andrés Pedroza Valdés; Mario Alberto Rodríguez Moreno

    2010-01-01

    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 rea...

  5. 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%.

  6. 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....... The concept of learning objects and how they are used to form new courses are discussed....

  7. 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.

  8. 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...

  9. Evaluating an Inquiry-based Bioinformatics Course Using Q Methodology

    Science.gov (United States)

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

    2008-06-01

    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 backgrounds of a diverse set of students, predominantly computer science and biology undergraduate and graduate students. Although the researchers desired to investigate student views of the course, they were interested in the potentially different perspectives. Q methodology, a measure of subjectivity, allowed the researchers to determine the various student perspectives in the bioinformatics course.

  10. 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…

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

    DEFF Research Database (Denmark)

    Shinde, Vikas

    2013-01-01

    Theory of Machines and Mechanisms course is one of the essential courses of Mechanical Engineering undergraduate curriculum practiced at Indian Institute. Previously, this course was taught by traditional instruction based pedagogy. In order to achieve profession specific skills demanded by the i...

  12. 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…

  13. Design and Implementation of a Multimedia CD-ROM-Based Directed Study Preservice Teacher Education Course.

    Science.gov (United States)

    Morse, Timothy

    This paper discusses the development and implementation of a computer-based directed study preservice teacher education course. Specifically, it explains the procedures followed to create the ten multimedia CD-ROMs that comprise the course, and how preservice teachers use the CD-ROMs. Topics to be covered include (1) rationale for course creation;…

  14. 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…

  15. 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…

  16. 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…

  17. 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…

  18. Course development for web-based nursing education programs.

    Science.gov (United States)

    Schnetter, Vicki A; Lacy, Darlene; Jones, Melinda Mitchell; Bakrim, Khadija; Allen, Patricia E; O'Neal, Cynthia

    2014-11-01

    Developing and launching online programs requires nurse educators to reframe content and rethink traditional teaching methodologies. Creating a framework for course design and standardization of templates can result in online learning that is student centered while allowing the institution to scale up enrollment with quality education at the core. This article explores the considerations needed for effective, interactive online course delivery in nursing education. Working in conjunction with other university technology stakeholders, nurse educators can select the learning management system with the features that will work best for the program, develop the course structure and organization through adherence to template rules for both syllabi and course modules, and develop appropriate learning activities to assure student exposure to content identified in the course objectives. With these structure pieces in place process becomes the second focus for nurse educators in online programs. Process activities for active engagement are discussed.

  19. "Full-Scale Testing of Pavement Response"

    DEFF Research Database (Denmark)

    Ullidtz, Per; Ekdahl, Peter

    1998-01-01

    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...

  20. Cracking of open traffic rigid pavement

    Directory of Open Access Journals (Sweden)

    Niken Chatarina

    2017-01-01

    Full Text Available The research is done by observing the growth of real structure cracking in Natar, Lampung, Indonesia compared to C. Niken’s et al research and literature study. The rigid pavement was done with open traffic system. There are two main crack types on Natar rigid pavement: cracks cross the road, and cracks spreads on rigid pavement surface. The observation of cracks was analyzed by analyzing material, casting, curing, loading and shrinkage mechanism. The relationship between these analysis and shrinkage mechanism was studied in concrete micro structure. Open traffic make hydration process occur under vibration; therefore, fresh concrete was compressed and tensioned alternately since beginning. High temperature together with compression, cement dissociation, the growth of Ca2+ at very early age leads abnormal swelling. No prevention from outside water movement leads hydration process occur with limited water which caused spreads fine cracks. Limited water improves shrinkage and plastic phase becomes shorter; therefore, rigid pavement can’t accommodate the abnormal swelling and shrinking alternately and creates the spread of cracks. Discontinuing casting the concrete makes both mix under different condition, the first is shrink and the second is swell and creates weak line on the border; so, the cracks appear as cracks across the road.

  1. 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...

  2. 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...

  3. 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

  4. 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

  5. Web Based Homework for CAPA in General Education Astronomy Courses

    Science.gov (United States)

    Robertson, T. H.

    2002-12-01

    Qualitative questions in astronomy have been developed to operate under the CAPA web-based homework system. Multiple versions of similar questions and software randomization are used to create different homework sets for each student. The questions are grouped by concept and subject to create more challenging activities from relatively simple questions. These questions have been used for three semesters in five sections of ASTRO 100 which enrolled a total of 500 students over the past two years. Student surveys consistently indicate that they like the system and believe that it helps them to learn. Cognitive measures in the form of exam and course grades do not demonstrate statistically significant improvement in sections which have used the new homework system. This is due in part to a conscious effort to create exam questions which focus on content understanding and not memorization and the persistent student habit of studying for exams by memorizing homework. Differences have been identified between female and male students in terms of completion rates and performance on homework, quiz and exam scores. This work was supported in part by funding from the George and Frances Ball Fund for Academic Excellence and the 21st Century Fund for Faculty Development.

  6. Designing for Differences: Cultural Issues in the Design of WWW-based Course-support Sites.

    Science.gov (United States)

    Collis, Betty

    1999-01-01

    Examines factors affecting the cultural appropriateness of Web-based course-support sites. Identifies a strategy for accommodating different values of these factors in Web-based course-support systems, based on a set of 10 design guidelines. Describes and evaluates the TeleTOP Method from the University of Twente (The Netherlands) to illustrate…

  7. Learning to Teach Inquiry: A Course in Inquiry-Based Science for Future Primary School Teachers

    Science.gov (United States)

    Kremer, Angelika; Walker, Mark; Schluter, Kirsten

    2007-01-01

    We developed a course in inquiry-based science for students training to become primary school teachers. The emphasis of the course was teaching students to do inquiry-based science activities themselves, as this is the best way of learning how to teach using inquiry-based methods. (Contains 1 table.)

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

    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

  9. Field Performance of Asphalt Pavements with New Technologies in Northern Nevada

    Science.gov (United States)

    Faeth, Benjamin Michael

    The Regional Transportation Commission (RTC) of the Washoe Valley Area has been tasked to determine if three advanced asphalt pavement technologies and one modified aggregate gradation are suitable for implementation within Reno, Stead, and Sparks Nevada. This was accomplished through research and test roads and Intersections to determine if Recycled Asphalt Pavement (RAP), Warm Mix Asphalt (WMA), Polymer-Modified Asphalt Binder, and the Type 2-R aggregate gradation were succeeding in their design plans. Over the course of several years the streets being used by RTC to test the technologies are succeeding within their design lifespans, and the Intersections being used to test the Type 2-R aggregate gradation are showing significant resistance to rutting. Due to the roads and Intersections not being more than 10 years old, these conclusions are subject to change over time.

  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. Multimedia comprehension skill predicts differential outcomes of web-based and lecture courses.

    Science.gov (United States)

    Maki, William S; Maki, Ruth H

    2002-06-01

    College students (134 women and 55 men) participated in introductory psychology courses that were offered largely online (on the World Wide Web) or in a lecture format. Student comprehension skills were inferred from their scores on a multimedia comprehension battery. The learning of content knowledge was affected interactively by comprehension skill level and course format. Differences between format increased with comprehension skill such that the Web-based course advantage became greater as comprehension skill increased. This same pattern was not seen when self-reports of comprehension ability were used as the predictor. Furthermore, comprehension skill did not predict course satisfaction. Generally, students of all skill levels preferred the lecture courses.

  12. Care and Feeding of a Paperless, Calculus-based Physics Course

    Science.gov (United States)

    Moore, Christopher; Fuller, Robert; Plano-Clark, Vicki L.; Dunbar, Steven R.

    1997-04-01

    Technology is playing an increasing role in our lives at home, at work, and in the classroom. We have begun a calculus-based introductory physics course to integrate mathematics and multimedia with the traditional physics content. This course relies on the use of technology to teach physics. We formulated the following rule for the conduct of the course: ''No paper is transferred between instructional staff and students that contains course information or assignments for grading.'' Implementing and maintaining this physics course within the context of the instructor goals will be discussed. Preliminary results of feedback from the students and an evaluation team will be presented.

  13. Structural analyses of a rigid pavement overlaying a sub-surface void

    Science.gov (United States)

    Adam, Fatih Alperen

    Pavement failures are very hazardous for public safety and serviceability. These failures in pavements are mainly caused by subsurface voids, cracks, and undulation at the slab-base interface. On the other hand, current structural analysis procedures for rigid pavement assume that the slab-base interface is perfectly planar and no imperfections exist in the sub-surface soil. This assumption would be violated if severe erosion were to occur due to inadequate drainage, thermal movements, and/or mechanical loading. Until now, the effect of erosion was only considered in the faulting performance model, but not with regards to transverse cracking at the mid-slab edge. In this research, the bottom up fatigue cracking potential, caused by the combined effects of wheel loading and a localized imperfection in the form of a void below the mid-slab edge, is studied. A robust stress and surface deflection analysis was also conducted to evaluate the influence of a sub-surface void on layer moduli back-calculation. Rehabilitative measures were considered, which included a study on overlay and fill remediation. A series regression of equations was proposed that provides a relationship between void size, layer moduli stiffness, and the overlay thickness required to reduce the stress to its original pre-void level. The effect of the void on 3D pavement crack propagation was also studied under a single axle load. The amplifications to the stress intensity was shown to be high but could be mitigated substantially if stiff material is used to fill the void and impede crack growth. The pavement system was modeled using the commercial finite element modeling program Abaqus RTM. More than 10,000 runs were executed to do the following analysis: stress analysis of subsurface voids, E-moduli back-calculation of base layer, pavement damage calculations of Beaumont, TX, overlay thickness estimations, and mode I crack analysis. The results indicate that the stress and stress intensity are, on

  14. 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.

  15. Field Test and Numerical Simulation of Dynamic Response of Semi-rigid Base Asphalt Pavement under Moving Vehicle Load%动载作用下半刚性基层沥青路面动力响应现场测试及数值模拟

    Institute of Scientific and Technical Information of China (English)

    张静; 魏连雨; 马士宾; 王涛

    2016-01-01

    Relying on the real project, the dynamic response of semi-rigid base asphalt pavement under moving vehicle load is studied based on the field test and 3D finite element simulation. First, the field test of the dynamic response of semi-rigid base asphalt pavement is conducted using fiber grating sensing technology. The dynamic theory, the moving vehicle load condition, the boundary condition and the structural parameters for the FE transient analysis are determined according to the field test result, and a 3D finite element model of the asphalt pavement is established. Then, the internal dynamic response feature of the pavement under different axle loads and material parameters are analysed. The result indicates that (1) under moving vehicle load, the stress state of the pavement tends to adverse with the decreasing of vehicle speed; ( 2 ) the longitudinal (the same as the driving direction) tensile strain is greater than the transverse tensile strain;(3) as the load increases, the volatility of strain response of the pavement is enhanced, and the tensile and compressive strains in the asphalt layer change alternately and dramatically;(4) the effect of surface modulus on the compressive strain on the top of subgrade is more significant than the base modulus, but the base modulus has a great impact on tensile strain at the bottom of surface.%依托实际工程,基于现场检测和三维有限元模拟技术,研究动载作用下半刚性基层沥青路面动力响应.首先,基于光纤光栅传感技术进行半刚性基层沥青路面动力响应现场测试,依据现场测试结果,确定有限元瞬态分析的动力学原理、 荷载条件、 边界条件及材料参数,建立沥青路面三维有限元模型;然后分析不同轴载及材料参数下路面结构内部的动力响应特征.结果表明,动载作用下,车速越低,路面结构受力状态越不利;纵向(行车方向)拉应变大于横向拉应变;随轴载的增大,路面结构的应变响

  16. 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.

  17. Volatilization of polycyclic aromatic hydrocarbons from coal-tar-sealed pavement

    Science.gov (United States)

    Van Metre, Peter C.; Majewski, Michael S.; Mahler, Barbara J.; Foreman, William T.; Braun, Christopher L.; Wilson, Jennifer T.; Burbank, Teresa L.

    2012-01-01

    Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, are a potential source of volatile PAHs to the atmosphere. An initial assessment of volatilization of PAHs from coal-tar-sealed pavement is presented here in which we measured summertime gas-phase PAH concentrations 0.03 m and 1.28 m above the pavement surface of seven sealed (six with coal-tar-based sealant and one with asphalt-based sealant) and three unsealed (two asphalt and one concrete) parking lots in central Texas. PAHs also were measured in parking lot dust. The geometric mean concentration of the sum of eight frequently detected PAHs (ΣPAH8) in the 0.03-m samples above sealed lots (1320 ng m-3) during the hottest part of the day was 20 times greater than that above unsealed lots (66.5 ng m-3). The geometric mean concentration in the 1.28-m samples above sealed lots (138 ng m-3) was five times greater than above unsealed lots (26.0 ng m-3). Estimated PAH flux from the sealed lots was 60 times greater than that from unsealed lots (geometric means of 88 and 1.4 μg m-2 h-1, respectively). Although the data set presented here is small, the much higher estimated fluxes from sealed pavement than from unsealed pavement indicate that coal-tar-based sealants are emitting PAHs to urban air at high rates compared to other paved surfaces.

  18. Truck fleet model for design and assessment of flexible pavements

    OpenAIRE

    Belay, Abraham; O'Brien, Eugene J.; Kroese, Dirk P.

    2008-01-01

    The mechanistic empirical method of flexible pavement design/assessment uses a large number of numerical truck model runs to predict a history of dynamic load. The pattern of dynamic load distribution along the pavement is a key factor in the design/ assessment of flexible pavement. While this can be measured in particular cases, there are no reliable methods of predicting the mean pattern for typical traffic conditions. A simple linear quarter car model is developed here which aims to reprod...

  19. 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.

  20. Dynamic Response Analysis of Asphalt Concrete Pavement with Permeable Base Considering Moving and Overload Effect of Vehicles%考虑车辆移动效应和超载的排水基层路面结构动力分析

    Institute of Scientific and Technical Information of China (English)

    欧金秋; 崔新壮; 王聪; 郑骁

    2011-01-01

    In order to study the dynamic response of asphalt concrete pavement with permeable base under vehicle loads, based fast Lagrangian finite difference method, the dynamic analysis of asphalt concrete pavement under various conditions is conducted, considering the influence of moving vehicle load and different speed. The results show that the pavement dynamic deflection did not increase though the modulus of permeable base is low. The permeable base reduced the dynamic stress at the bottom of the subbase, which can inhibit the cracking of reflection. With the increase of speed, both the dynamic deflection and stress decreased, so in high temperature season, low-speed vehicle can cause larger rutting. Little vehicle overload can induce larger dynamic deflection and stress thus causes larger pavement deformation even plastic damage and the cracking. It is implied that the governance of overload is of great significance for extending road life and reducing maintenance costs.%为了研究车辆荷载作用下排水基层路面的动力响应,同时考虑车速和轴载的影响,采用移动加载的方法,对不同工况下沥青混凝土路面进行了快速Lagrange有限差分分析.结果表明,路面弯沉并未因排水基层的低模量而增大,峰值甚至有所减小;排水基层的存在减小了底基层底部的动应力,可以抑制反射裂缝的产生;弯沉及动应力均随车速的增大而减小,高温季节,低速行驶更容易引起大车辙;当车辆超载50%时,弯沉和动应力均成倍增大,导致路面产生较大变形甚至塑性破坏,且更容易引起路面开裂,表明治理超载对延长道路使用寿命、降低养护成本具有重要意义.

  1. 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.

  2. 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…

  3. Building Evaluation of Collaborative Learning into a WWW-Based Course: Pedagogical and Technical Experiences.

    Science.gov (United States)

    Collis, Betty

    1998-01-01

    A first-year course in the computer-based educational media design curriculum at the University of Twente (Netherlands) uses the World Wide Web as an integrated course environment; collaborative group-based learning is the basis of the instruction. The Web is used to make evaluation-oriented activities part of the ongoing student experience.…

  4. 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…

  5. 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…

  6. 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...

  7. Fast segmentation of industrial quality pavement images using Laws texture energy measures and k -means clustering

    Science.gov (United States)

    Mathavan, Senthan; Kumar, Akash; Kamal, Khurram; Nieminen, Michael; Shah, Hitesh; Rahman, Mujib

    2016-09-01

    Thousands of pavement images are collected by road authorities daily for condition monitoring surveys. These images typically have intensity variations and texture nonuniformities that make their segmentation challenging. The automated segmentation of such pavement images is crucial for accurate, thorough, and expedited health monitoring of roads. In the pavement monitoring area, well-known texture descriptors, such as gray-level co-occurrence matrices and local binary patterns, are often used for surface segmentation and identification. These, despite being the established methods for texture discrimination, are inherently slow. This work evaluates Laws texture energy measures as a viable alternative for pavement images for the first time. k-means clustering is used to partition the feature space, limiting the human subjectivity in the process. Data classification, hence image segmentation, is performed by the k-nearest neighbor method. Laws texture energy masks are shown to perform well with resulting accuracy and precision values of more than 80%. The implementations of the algorithm, in both MATLAB® and OpenCV/C++, are extensively compared against the state of the art for execution speed, clearly showing the advantages of the proposed method. Furthermore, the OpenCV-based segmentation shows a 100% increase in processing speed when compared to the fastest algorithm available in literature.

  8. New U.S. pavement design guide will have major impact in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Hein, D.

    2002-03-31

    The potential impacts and benefits that are likely to accrue to Canada with the upcoming release of the 2002 Pavement Design Guide of the American Association of State Highway and Transportation Officials (ASSHTO) are reviewed. The impact will be felt through AASHTO's 2002 mechanistic-empirical design method, a multi-level hierarchical approach based on design data requirements reflecting roadway classification and current roadway use configurations. A significant departure from the previous system is the emphasis on vehicle axle load distribution rather than equivalent single axle loads to evaluate pavement loading over service life. Specific benefits include: (1) consideration of inherent variations in materials, traffic and environmental factors in construction processes facilitating agency managers to be better able to weigh life cycle costs and cash flow in their decision making processes; (2) enhanced cost-responsibility studies through the improved ability to evaluate consequences of new pavement loading conditions; (3) ability of designers to use available and evolving materials ; (4) improved evaluation of premature pavement failures through better diagnostic techniques; and (5) better assessment of the effects of aging and that of the freeze-thaw cycle through better environmental data and analysis.

  9. 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.

  10. Design of Road Pavement Using Recycled Aggregate

    Science.gov (United States)

    Remišová, Eva; Decký, Martin; Mikolaš, Milan; Hájek, Matej; Kovalčík, Luboš; Mečár, Martin

    2016-10-01

    The presented article gives special attention to codified clauses of the road construction law, the relevant clauses of the standards and technical regulations to design and control the quality of recycled aggregate constructions. The article also presents the authors’ suggestions to design of earth constructions and pavements of roads according to the Slovak technical standards, technical regulations and objectively determined results of research and development of road infrastructure. The article presents a comparison of the mechanical characteristics measurements of the structural layers of road pavements built from the recycled and natural aggregate. It also presents correlation functions of results obtained from in situ and in laboratory CBR (Californian Bearing Ratio) measuring, representing the world's most widely used control method of bearing capacity of mentioned construction layers.

  11. 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…

  12. Environmental history recorded in eolian deposits under stone pavements, eastern Mojave Desert, USA

    Science.gov (United States)

    Wells, Stephen; Fuchs, Markus; Dietze, Elisabeth; Lomax, Johanna; Kleber, Arno; Dietze, Michael

    2016-04-01

    Reconstructing the evolution of arid landscapes is challenged by the limited availability of appropriate environmental archives. A widespread surface feature of arid landscapes - stone pavement - traps eolian fines and can form an accretionary archive, growing with time and thereby recording essential information about the conditions under which it evolves. Based on a regional example in the eastern Mojave Desert, USA, seven stone pavement-covered soil-sediment sections on 560 and 270 ka old basalt flows are condensed to a correlation framework, comprising five distinct, successive sedimentological units. An OSL-based chronology enables correlation of this new sediment archive with other environmental archives from the region. Three of the stratigraphic units are of accretionary nature and the top of each unit is mantled by a new generation of stone pavement. These stratigraphic units were deposited between >32.3-20.4 ka, 20.4-16.5 ka and younger than 16.5 ka, appearing to be strongly coupled with the history of the nearby ancient Lake Mojave and enhancing our knowledge of the eolian activity in this area. End-member modelling analysis of sampled grain-size distributions allows identification of a local detritus component, four separate eolian components and two distinct clay enrichment components, contributing different quantities of sediment sources to the five stratigraphic units. These findings improve current concepts about the evolution of stone pavements and their role as conveyers of information about environmental conditions in arid landscapes. Stone pavement-covered accretionary sediment deposits are a new key archive that allows quantifying the relative importance of dust accretion, slope processes, soil formation and vegetation cover.

  13. 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.

  14. 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.

  15. 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.

  16. Prediction of Pavement Condition Index Based on Grey Markov Model%基于灰色马尔可夫模型的路面状况指数预测

    Institute of Scientific and Technical Information of China (English)

    张亮

    2011-01-01

    With the increase of using years, the decline of pavement quality is not avoided. In order to lengthen the service life of pavements, highway maintenance management departments should take right conservation measures at the right time. Many areas in China have studied on the right preventive maintenance time and maintenance measures in recent years. As the basis of preventive maintenance, the prediction of pavement quality can provide the theoretical basis for highway maintenance management departments. The prediction of pavement condition index by the grey Markov model is taken. The model has the advantages of gray model and Markov mode and has a good prediction precision. Compared with the other model, the results showed that the model has a better practicality.%随着公路使用年数的增加,路面使用性能的衰减不可避免.为延长道路使用寿命,公路养护管理单位需要在适当的时间采取合适的路面养护措施.近年来,我国多个地区开展了预防性养护时机和养护措施的研究.路面使用性能的预测作为预防性养护的基础,可以给公路管理部门提供决策依据.运用灰色马尔可夫模型对路面破损状况进行预测.模型兼有灰色预测和马尔可夫预测的优点,预测精度较高.实例表明,与其他模型相比,该模型有较高的实用性.

  17. Research on Application Urban Permeable Pavement Based on the Concept of Sponge City%海绵城市理念下城市透水性铺装的应用研究

    Institute of Scientific and Technical Information of China (English)

    应君; 张青萍

    2016-01-01

    海绵城市是应对我国快速城镇化过程中出现的严重水环境问题而提出的一种新理念,透水性铺装技术是低影响开发雨水系统的重要手段。首先,对城市下垫面硬化带来的弊端进行了分析,然后,从海绵城市的角度提出了透水性铺装对恢复城市良性水文循环机制的作用。在此基础上对透水铺装材料的物理特性、适用范围、后期养护、设计流程等方面进行了系统论述,以期为在海绵城市建设中更好地应用透水铺装提供借鉴。%“Sponge city” is a new concept to solve serious problem of water environment in the process of rapid urbanization in China. And permeable pavement is an important means of low impact development. First, the paper analyzes the problem of city underlying surface hardening. Second, it introduces the role of permeable pavement to restore urban hydrologic cycle from the perspective of “sponge city”. At last, it puts forward the aspects of permeable pavement details, including physical properties, scope of application, maintenance, design process. It has the positive significance to apply the permeable pavement in the construction of “sponge city”.

  18. Developing and providing an online (web-based) clinical research design course in Japan: lessons learned.

    Science.gov (United States)

    Clark, Glenn T; Mulligan, Roseann; Baba, Kazuyoshi

    2011-04-01

    This article reports on the lessons learned while teaching an 8-week-long online course about the principles of clinical research design in Japan. Student activity data and how it relates to performance in the course are presented. As prolog, this article focuses on the barriers and solutions to creating and delivering a web-based course and it lists and discusses the most common concerns that educators often have about this process, namely, cost of the system and time requirement of the faculty. Options that must be considered when selecting the support software and hardware needed to conduct live streaming lecture, online video-based conference course are presented. The ancillary role of e-mail based distribution lists as an essential instruction tool within an interactive, instructor-supervised online course is discussed. This article then discusses the inclusion of active learning elements within an online course as well as the pros and cons regarding open-book versus closed book, proctored testing. Lastly, copyright issues the online instructor should know about are discussed. The student tracking data show that as the course progresses, students will reduce the number for page viewings. We speculate that this reduction is due to a combination of conflicting priorities plus increasing efficiency of the students at extracting the critical information. The article also concludes that software and hardware costs to deliver an online course are relatively minor but the faculty's time requirement is initially substantially higher than teaching in a conventional face-to-face course.

  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. Anti-sliding performance analysis of cement concrete pavement based on BP neural network%基于BP神经网络的水泥混凝土路面抗滑性能分析

    Institute of Scientific and Technical Information of China (English)

    喻小毛

    2012-01-01

    以水泥混凝土路面材料设计方案以及月降水量为输入,以路面摩擦系数表征路面抗滑性能为输出,利用BP神经网络分析水泥混凝土路面抗滑性能,研究表明,BP网络能考虑不同公路的实际差异,找到路面材料设计方案及月降水量与抗滑性能的最佳组合,为实际施工提供指导。%Taking cement concrete pavement material design scheme and monthly precipitation as the input, and taking anti-friction coefficient embodying anti-sliding property as the output, the paper analyzes the anti-sliding performance of cement concrete pavement by applying BP neu- ral network. Results show that BP network finds out the optimal combination of pavement material design scheme and monthly precipitation and anti-sliding performance by considering various highway conditions, which has provided guidance for actual construction.

  1. 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.

  2. 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...

  3. 山区2级公路路面早期大面积疲劳破坏状况研究%Research on Large-area Fatigue Damage Conditions of Second Class Highway Pavements at Early Stage in Mountainous Areas

    Institute of Scientific and Technical Information of China (English)

    唐颖

    2011-01-01

    通过对某山区2级公路沥青路面交通量、气象资料、弯沉测定、钻芯试验、路面结构以及排水设施等方面的调查分析,得出该路面出现早期大面积疲劳开裂破坏产生的原因为:超载严重导致基层层底实际拉应力大于设计拉应力而出现疲劳破坏;边沟未设泄水孔、土路肩,致使路基形成封闭水域而导致结构层积水;面层过薄、路面开裂导致雨水下渗并汇聚在面层基层之间产生冲刷破坏;气温骤降导致面层温缩开裂.研究结果将为南方多雨重交通地区的2级公路设计、施工及维护提供一定的参考依据.%Based on investigation and analysis for volume of traffic, meteorological data, deflection measurement, core test, pavement structure and drainage facilities, etc. Of asphalt pavement of some second class highway in mountainous area, this paper obtains causes for large-area fatigue cracking damage on this pavement at early stage, including fatigue damage due to actual tensile stress on the bottom of base course which is bigger than designed tensile stress caused by serious overload; water logging in structural layer due to enclosed water area on roadbed caused by no drainage openings and earth shoulders equipped for side ditches; scouring damage produced due to infiltration of rainwater and convergence between surface course and base course caused by too thin surface course and cracking of pavement; and temperature shrinkage crack of surface course due to abrupt decrease of air temperature. The research result of this paper will provide certain reference basis for design, construction and maintenance of second class highways in southern areas with more rain and heavy traffic.

  4. Assessing the FACTTS: an evidence-based medicine and critical appraisal course for medical students.

    Science.gov (United States)

    Cyrus, John W W; Duggar, David C; Woodson, Deidra; Timm, Donna F; McLarty, Jerry W; Pullen, Kimberly; Baggett, Mark P; Banks, Daniel E

    2013-01-01

    The Fourth-year Academic Clinical Training and Teaching Selective (FACTTS) is a course taught by medical and library faculty on the practice of evidence-based medicine and critical appraisal of the medical literature. This study assesses the impact of the course on students' understanding of the subject matter by examining three years of pre- and post-test data and addresses whether the number of sessions in the course affects the knowledge gained by the students. The data show an improvement in the students' understanding of course material, but no benefit was found in having two versus three sessions.

  5. 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.

  6. 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.

  7. 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…

  8. Reality-Based Learning: Outbreak, an Engaging Introductory Course in Public Health and Epidemiology

    Science.gov (United States)

    Calonge, David Santandreu; Grando, Danilla

    2013-01-01

    Objective: To develop a totally online reality-based course that engages students and enables the development of enhanced teamwork and report-writing skills. Setting: Outbreaks of infectious diseases impacts upon commerce, trade and tourism as well as placing strains on healthcare systems. A general course introducing university students to…

  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. 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…

  11. 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…

  12. 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…

  13. 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…

  14. Experiential, Team-Based Learning in a Baccalaureate Social Work Research Course

    Science.gov (United States)

    Venema, Rachel; Meerman, Judi Ravenhorst; Hossink, Kristin

    2015-01-01

    This article describes student responses to a BSW research course framed by experiential learning theory to engage the community and offer applied research practice. The study finds that students generally express overall satisfaction with the research course and describe perceptions of learning gains when involved in a team-based research project…

  15. 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.…

  16. 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…

  17. 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…

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

    Science.gov (United States)

    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…

  19. Collaborating to Improve Inquiry-Based Teaching in Elementary Science and Mathematics Methods Courses

    Science.gov (United States)

    Magee, Paula A.; Flessner, Ryan

    2012-01-01

    This study examines the effect of promoting inquiry-based teaching (IBT) through collaboration between a science methods course and mathematics methods course in an elementary teacher education program. During the collaboration, preservice elementary teacher (PST) candidates experienced 3 different types of inquiry as a way to foster increased…

  20. 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…

  1. 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…

  2. Exploring the Principles Underlying Business English Course Design-Based on a Training Program

    Institute of Scientific and Technical Information of China (English)

    王松昌

    2014-01-01

    In order to make a business English training course cost effective, the course is to be designed based on certain language teaching theories and principles involving needs analysis to identify learners’needs and wants, appropriate teaching approaches and during-and-after evaluation of the training effects.

  3. 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.

  4. Effect of induced deformation on NDT pavement evaluation

    Science.gov (United States)

    Tawfiq, Kamal S.; Sobanjo, John O.; Ruiz, R.

    1999-02-01

    Three nondestructive testing techniques were used in this study to evaluate pavement layer properties. These techniques included deflection and seismic methods. In the deflection methods, measurable surface deformations were induced using falling weight deflectometer and Dynaflect tests. These two tests utilized different schemes of dynamic loading applications to produce deflection basins from which the pavement layer properties were back calculated. Pavement properties from seismic methods were obtained from the analysis of surface waves due to transient load applications. In this study the seismic pavement analyzer (SPA) was used to determine pavement moduli values. Although the same assumptions for linear elastic behavior of pavement properties are usually assumed in all the three methods, obtained moduli values from these techniques did not conform to each other. Commonly, pavement deflection from SPA is not considered when analyzing layer properties. To narrow the gap between the obtained results, however, time-history records and frequency response functions were used to determine surface deflections from the three methods. Deflection measurements correlated with the obtained moduli values. Using these correlations, moduli values at any pavement deflection levels could be evaluated, especially at levels produced by traffic loads.

  5. A precepted leadership course based on Bandura's social learning theory.

    Science.gov (United States)

    Haddock, K S

    1994-01-01

    Transition from student to registered nurse (RN) has long been cited as a difficult time for new graduates entering health care. Bandura's (1977) theory of social learning guided a revision of a nursing leadership course required of baccalaureate student nurses (BSNs) in their final semester. The preceptorship allowed students to work closely with and to practice modeled behaviors of RNs and then receive feedback and reinforcement from both the preceptor and the supervising faculty member. Students were thus prepared to function better in the reality of the practice setting. Positive outcomes were experienced by students, BSN preceptors, faculty, and nurse administrators.

  6. 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...

  7. Reforming a large lecture modern physics course for engineering majors using a PER-based design

    CERN Document Server

    McKagan, S B; Wieman, C E

    2006-01-01

    We have reformed a large lecture modern physics course for engineering majors by radically changing both the content and the learning techniques implemented in lecture and homework. Traditionally this course has been taught in a manner similar to the equivalent course for physics majors, focusing on mathematical solutions of abstract problems. Based on interviews with physics and engineering professors, we developed a syllabus and learning goals focused on content that was more useful to our actual student population: engineering majors. The content of this course emphasized reasoning development, model building, and connections to real world applications. In addition we implemented a variety of PER-based learning techniques, including peer instruction, collaborative homework sessions, and interactive simulations. We have assessed the effectiveness of reforms in this course using pre/post surveys on both content and beliefs. We have found significant improvements in both content knowledge and beliefs compared...

  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. Using a web-based course-management system: an evaluation of management tasks and time implications for the instructor

    NARCIS (Netherlands)

    Gervedink Nijhuis, Gerard; Collis, Betty

    2003-01-01

    Almost all the instructors at the Faculty of Educational Science and Technology of the University of Twente have been using a web-based course-management system for their courses since 1998. To set up a course, an instructor completes a course environment form with general information such as a cour

  10. Adaptive Road Crack Detection System by Pavement Classification

    Directory of Open Access Journals (Sweden)

    Alejandro Amírola

    2011-10-01

    Full Text Available This paper presents a road distress detection system involving the phases needed to properly deal with fully automatic road distress assessment. A vehicle equipped with line scan cameras, laser illumination and acquisition HW-SW is used to storage the digital images that will be further processed to identify road cracks. Pre-processing is firstly carried out to both smooth the texture and enhance the linear features. Non-crack features detection is then applied to mask areas of the images with joints, sealed cracks and white painting, that usually generate false positive cracking. A seed-based approach is proposed to deal with road crack detection, combining Multiple Directional Non-Minimum Suppression (MDNMS with a symmetry check. Seeds are linked by computing the paths with the lowest cost that meet the symmetry restrictions. The whole detection process involves the use of several parameters. A correct setting becomes essential to get optimal results without manual intervention. A fully automatic approach by means of a linear SVM-based classifier ensemble able to distinguish between up to 10 different types of pavement that appear in the Spanish roads is proposed. The optimal feature vector includes different texture-based features. The parameters are then tuned depending on the output provided by the classifier. Regarding non-crack features detection, results show that the introduction of such module reduces the impact of false positives due to non-crack features up to a factor of 2. In addition, the observed performance of the crack detection system is significantly boosted by adapting the parameters to the type of pavement.

  11. 混凝土砂基透水路面砖制备及物理性能测试%Precasting method and physical property test of sand-based concrete permeable pavement bricks

    Institute of Scientific and Technical Information of China (English)

    徐向舟; 朱晓斌; 刘璐; 王云闯; 王萍萍

    2014-01-01

    Promoting sand-based permeable brick is an effective way to recycle desert sand.A kind of sand-based permeable brick with precast permeable pores is developed.The brick is composed with roast sand as the aggregate and high-strength grading concrete as the binder,and is formed under static pressure.A series of physical performance tests and cost analyses are then conducted.The results are as follows:(1)Compressive strength of the permeable brick reaches up to 100 MPa,which is highly above the requirement of Cc60 permeable brick in the Construction Material Industry Standard in China.(2 )The pre-fabricated penetrating hole makes the permeability of the brick far ahead of the Construction Material Industry Standard in China.Moreover,it is not so easy to clog, and does not influence the comfort of the pavement,for the hole is so small in diameter on the top and large at the bottom.(3)Comprehensively considering the compressive strength,permeability,water retention,cost and so on,the following two schemes are chosen for future study:The 20th group is selected as the high-strength permeable brick,of which the fine sand ratio is 70%,the water cement ratio is 0.34,the porosity is 2% and the additive is the aqueous neoprene,in short AN;and the 22th group is more suitable to be used on the plaza pavement,of which the fine sand ratio is 85%,the water cement ratio is 0.30,the porosity is 1%,and no additive is added.(4)Increasing the coarse aggregate content could significantly augment the compressive strength of permeable brick. A preferable fine sand ratio is 70%-85%.(5)On the other hand,to mix an appropriate kind of additive with proper dosage is another way to enhance the brick.(6)Except higher cost of groups 7,11,12, 19,the cost of other groups is between 60-100 Yuan/m2 ,which is close to that of general no-sand permeable concrete brick,and far lower than that of the same kind of sand-based permeable brick.%推广砂基透水砖是实现沙漠沙资源化的有效途径.

  12. Utilization of Advanced Diagnostic Methods for Texture and Rut Depth Analysis on a Testing Pavement Section

    Science.gov (United States)

    Slabej, Martin; Grinč, Michal; Kotek, Peter; Kováč, Matúš; Decký, Martin

    2015-05-01

    Qualitative characteristics of pavement in wide range reflects the pavement serviceability, which is a summary of the characteristics of the pavement, providing a fast, smooth, economical and especially safe driving of motor-vehicles. The target factor of pavement serviceability and safety of roads represents the quality of their surface properties. In the framework of research activities performed in the Research Centre founded under the auspices of University of Žilina, individual parameters of pavement serviceability were monitored by pavement surface scanning. This paper describes the creation of a 3D - road surface model and its analysis and evaluation from the viewpoint of two pavement serviceability parameters - the rut depth and texture. Measurements were performed on an experimental pavement section used contemporary in an Accelerated Pavement Testing experiment. The long-term goal is to ascertain functions predicting degradation of these two pavement serviceability parameters.

  13. Incorporation of Blended Learning in Introductory Courses: A Research-Based Approach to Evaluation

    Science.gov (United States)

    Strey, S. T.; Charlevoix, D. J.; Guarente, B. A.; Snodgrass, E. R.

    2008-12-01

    We evaluate the learning outcomes of students in large enrollment classes comparing a blended learning course format and a traditional lecture section. Blended learning, here, describes instruction that is a combination of face-to-face meeting with asynchronous online learning, resulting in reduced class time. The course, Severe and Hazardous Weather, relies heavily on graphics and animations of weather events available online, both current and archived, and thereby lends itself well to a blended format. Severe and Hazardous Weather is a popular general education requirement course at the University of Illinois with consistently high enrollments (greater than 200 students per section) and classes at capacity. Unlike many past studies, this blended learning format is applied to a large-enrollment course of approximately 100 students. Curriculum was redesigned during fall 2007 from typical lecture to the blended format. The redesign process followed best practices grounded in peer-reviewed literature on blended and online learning. We will provide a brief overview of the course structure, but focus on the evaluation of both the curriculum design and student outcomes as compared to the traditional lecture-based course. Evaluation is based on course objectives stated in the course syllabus and is conducted following best practices; the research project received University Institutional Review Board approval prior to the start of the study.

  14. 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...

  15. 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.

  16. 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.

  17. 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…

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Peer-Review Writing Workshops in College Courses: Students’ Perspectives about Online and Classroom Based Workshops

    OpenAIRE

    Erin B. Jensen

    2016-01-01

    Peer-review workshops are commonly used in writing courses as a way for students to give their peers feedback as well as help their own writing. Most of the research on peer-review workshops focuses on workshops held in traditional in-person courses, with less research on peer-review workshops held online. Students in a freshman writing course experienced both a classroom based writing workshop and an online workshop and then took a survey about their experiences. The majority of the students...

  3. 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

  4. Implementing Web-Based Scientific Inquiry in Preservice Science Methods Courses

    Science.gov (United States)

    Bodzin, Alec M.

    2005-01-01

    This paper describes how the Web-based Inquiry for Learning Science (WBI) instrument was used with preservice elementary and secondary science teachers in science methods courses to enhance their understanding of Web-based scientific inquiry. The WBI instrument is designed to help teachers identify Web-based inquiry activities for learning science…

  5. 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…

  6. A Web-based e-learning course: integration of pathophysiology into pharmacology.

    Science.gov (United States)

    Tse, Mimi M Y; Lo, Lisa W L

    2008-11-01

    The Internet is becoming the preferred place to find information. Millions of people go online in search of health and medical information. Likewise, the demand for Web-based courses is growing. This paper presents the development, utilization, and evaluation of a Web-based e-learning course for nursing students, entitled Integration of Pathophysiology into Pharmacology. The pathophysiology component included cardiovascular, respiratory, central nervous and immune system diseases, while the pharmacology component was developed based on 150 commonly used drugs. One hundred and nineteen Year 1 nursing students took part in the course. The Web-based e-learning course materials were uploaded to a WebCT for students' self-directed learning and attempts to pass two scheduled online quizzes. At the end of the semester, students were given a questionnaire to measure the e-learning experience. Their experience in the e-learning course was a positive one. Students stated that they were able to understand rather than memorize the subject content, and develop their problem solving and critical thinking abilities. Online quizzes yielded satisfactory results. In the focus group interview, students indicated that they appreciated the time flexibility and convenience associated with Web-based learning, and also made good suggestions for enhancing Web-based learning. The Web-based approach is promising for teaching and learning pathophysiology and pharmacology for nurses and other healthcare professionals.

  7. 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.

  8. 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.

  9. Morphological Algorithms For The Analysis Of Pavement Structure

    Science.gov (United States)

    Grivas, Dimitri A.; Skolnick, Michael M.

    1989-11-01

    The applicability of morphological image processing techniques for the description of condition and analysis of pavement surfaces is examined. Morphological techniques can be used in the measurement of pavement media consisting of grain (aggregates) and binding substances (bituminous or Portland cement mixtures). Measurements of size and size distributions on surface features related to texture and distresses can be obtained via morphological opening and closing transformations and distributions. When correlated with actual physical measurements of such quantities, the presented morphological measures of size and size distributions may prove to be useful in characterizing the surface condition of both asphalt and concrete pavement structures.

  10. Problem-Based Learning Assessment for Information Systems Courses.

    Science.gov (United States)

    Yip, Willie; Ghafarian, Ahmad

    A promising recent development in tertiary education involves the application of problem-based learning as a curricular vehicle to develop student talent. Problem-based learning (PBL) is common in professional education, such as in medical, law, and business schools, and is becoming increasingly common in pre-college education. However, it is less…

  11. Using a Web-Based Course-Management System: An Evaluation of Management Tasks and Time Implications for the Instructor.

    Science.gov (United States)

    Nijhuis, Gerard Gervedink; Collis, Betty

    2003-01-01

    Used data from a Web-based course management system in use at the Faculty of Educational Science and Technology, University of Twente, The Netherlands since 1998 to analyze tasks instructors must manage while using such a system. Results from 51 courses contribute to more efficient use of the Web-based course management system. (SLD)

  12. 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…

  13. A New Form of the General Solution of the Elastic Space Axisymmetric Problem in Pavement Mechanics

    Directory of Open Access Journals (Sweden)

    Jia Liang

    2016-01-01

    Full Text Available In order to analyze the stress and displacement of pavement, a new form of the general solution of the elastic space axisymmetric problem is proposed by the method of mathematics reasoning. Depending on the displacement function put forward by Southwell, displacement function is derived based on Hankel transform and inverse Hankel transform. A new form of the general solution of the elastic space axisymmetric problem has been set up according to a few basic equations as the geometric equations, constitutive equations, and equilibrium equations. The present solution applies to elastic half-space foundation and Winkler foundation; the stress and displacement of pavement are obtained by mathematical deduction. The example results show that the proposed method is practically feasible.

  14. 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.

  15. Pedagogy for teaching and learning cooperatively on the Web: a Web-based pharmacology course.

    Science.gov (United States)

    Tse, Mimi M Y; Pun, Sandra P Y; Chan, Moon Fai

    2007-02-01

    The Internet is becoming a preferred place to find information. Millions of people go online in the search of health and medical information. Likewise, the demand for Web-based courses grows. This article presents the development, utilization and evaluation of a web-based pharmacology course for nursing students. The course was developed based on 150 commonly used drugs. There were 110 year 1 nursing students took part in the course. After attending six hours face to face lecture of pharmacology over three weeks, students were invited to complete a questionnaire (pre-test) about learning pharmacology. The course materials were then uploaded to a WebCT for student's self-directed learning and attempts to pass two scheduled online quizzes. At the end of the semester, students were given the same questionnaire (post-test). There were a significant increase in the understanding compared with memorizing the subject content, the development of problem solving ability in learning pharmacology and becoming an independent learner (p ,0.05). Online quizzes yielded satisfactory results. In the focused group interview, students appreciated the time flexibility and convenience associated with web-based learning, also, they had made good suggestions in enhancing web-based learning. Web-based approach is promising for teaching and learning pharmacology for nurses and other health-care professionals.

  16. 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.

  17. 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.

  18. Concentrations of polycyclic aromatic hydrocarbons (PAHs) and azaarenes in runoff from coal-tar- and asphalt-sealcoated pavement

    Science.gov (United States)

    Mahler, Barbara J.; Van Metre, Peter C.; Foreman, William T.

    2014-01-01

    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.

  19. Concentrations of polycyclic aromatic hydrocarbons (PAHs) and azaarenes in runoff from coal-tar- and asphalt-sealcoated pavement.

    Science.gov (United States)

    Mahler, Barbara J; Van Metre, Peter C; Foreman, William T

    2014-05-01

    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.

  20. Competency-based education in a clinical course in conservative dentistry.

    Science.gov (United States)

    Yip, H K; Smales, R J; Newsome, P R; Chu, F C; Chow, T W

    2001-11-10

    The conceptual difference between a competency-based education and an education based upon a conventional dental curriculum is, perhaps, the starting point for the development of new curricula. The two systems are not, in themselves, exclusive. There is common ground to be found, and the concept of combining instruction with competency-based learning experiences is emerging in recent publications. This paper describes a competency-based approach applied to a clinical course in conservative dentistry. The learning outcomes of the fourth-year dental students in the new course were assessed using methods that included continuous clinical assessments, student presentations and peer-group reflective evaluations, patient management reviews, a clinical progress examination, the range and amount of work completed, and a written examination and viva voce. Different weightings were given to various elements of the assessment. A formal student assessment of the course rated it as being satisfactory.

  1. 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.

  2. Partners in Learning: A Task-based Advanced Speaking Course.

    Science.gov (United States)

    O'Brien, Maureen

    This report describes a semester of teaching a group of non-native English-speaking students, aged 17 to 40 years and how the instructor identified three elements that appeared to be necessary for a task-based, advanced English speaking class. The three elements were: (1) ongoing needs assessment; (2) collaboration between instructor and students…

  3. On Interactive Teaching Model of Translation Course Based on Wechat

    Science.gov (United States)

    Lin, Wang

    2017-01-01

    Constructivism is a theory related to knowledge and learning, focusing on learners' subjective initiative, based on which the interactive approach has been proved to play a crucial role in language learning. Accordingly, the interactive approach can also be applied to translation teaching since translation itself is a bilingual transformational…

  4. 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

  5. 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.

  6. 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.

  7. Effect of Pavement Conditions on Rolling Resistance

    Directory of Open Access Journals (Sweden)

    Mr.Dipanjan Mukherjee

    2014-07-01

    Full Text Available Rolling resistance is the force acting on a vehicle over a full journey. It is generated by the hysteresis of tyre and pavement. Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement of the wheel, roadbed, etc. is recovered when the pressure is removed. A hysteresis phenomenon can be observed when viscoelastic materials undergo a load-then-unload process. A typical hysteresis curve of viscoelastic material can be found. The shadow area enclosed by the hysteresis loop represents energy loss. A characteristic of a deformable material such that the energy of deformation is greater than the energy of recovery. The rubber compound in a tire exhibits hysteresis. As the tire rotates under the weight of the vehicle, it experiences repeated cycles of deformation and recovery, and it dissipates the hysteresis energy loss as heat. Hysteresis is the main cause of energy loss associated with rolling resistance and is attributed to the viscoelastic characteristics of the rubber. Materials that have a large hysteresis effect, such as rubber, which bounce back slowly, exhibit more rolling resistance than materials with a small hysteresis effect that bounce back more quickly and more completely, such as steel or silica. Low rolling resistance tires typically incorporate silica in place of carbon black in their tread compounds to reduce low-frequency hysteresis without compromising traction. Note that railroads also have hysteresis in the roadbed structure. Like the fuel consumption, rolling resistance also has a significant relationship with velocity. experiment has shown that, for a 32-tonn goods vehicle, rolling resistance contributes about 70% of total drag when driven at 50km/h and about 37% at 100km/h. An important issue which should not

  8. How are "teaching the teachers" courses in evidence based medicine evaluated? A systematic review

    Directory of Open Access Journals (Sweden)

    Burnand Bernard

    2010-09-01

    Full Text Available Abstract Background Teaching of evidence-based medicine (EBM has become widespread in medical education. Teaching the teachers (TTT courses address the increased teaching demand and the need to improve effectiveness of EBM teaching. We conducted a systematic review of assessment tools for EBM TTT courses. To summarise and appraise existing assessment methods for teaching the teachers courses in EBM by a systematic review. Methods We searched PubMed, BioMed, EmBase, Cochrane and Eric databases without language restrictions and included articles that assessed its participants. Study selection and data extraction were conducted independently by two reviewers. Results Of 1230 potentially relevant studies, five papers met the selection criteria. There were no specific assessment tools for evaluating effectiveness of EBM TTT courses. Some of the material available might be useful in initiating the development of such an assessment tool. Conclusion There is a need for the development of educationally sound assessment tools for teaching the teachers courses in EBM, without which it would be impossible to ascertain if such courses have the desired effect.

  9. 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.

  10. [Asymptomatic skull base metastases: clinical course and therapeutic alternatives].

    Science.gov (United States)

    Vargas, A; Paulazo, C; Oleaga, L; Verger, E

    2017-03-01

    Introduccion. Las metastasis sintomaticas de la base craneal (MBC) son una progresion infrecuente, tardia y de mal pronostico en pacientes con tumores solidos. Sus manifestaciones clinicas pueden agruparse en cinco sindromes caracteristicos, y su tratamiento mas frecuente es la radioterapia. Gracias a los progresos tecnologicos en las pruebas de imagen y al seguimiento estrecho de los pacientes con cancer, las MBC pueden diagnosticarse incidentalmente. En este subgrupo no se conoce la evolucion clinica ni se ha establecido la mejor modalidad de tratamiento. Objetivo. Analizar las caracteristicas clinicas y la evolucion de los pacientes diagnosticados incidentalmente de MBC. Pacientes y metodos. Entre enero de 2012 y diciembre de 2015, 31 pacientes con una neoplasia solida diagnosticados de MBC fueron valorados por nuestro servicio. Resultados. Las MBC se diagnosticaron por la presencia de un sindrome de base craneal (n = 24) o incidentalmente (n = 7). Los pacientes sintomaticos fueron tratados con radioterapia. Todos los pacientes diagnosticados incidentalmente permanecieron sin sintomas relacionados con la afectacion de la base craneal hasta la fecha del fallecimiento, aunque frecuentemente presentaron de forma concomitante otros tipos de progresion intracraneal de mal pronostico. Se observo una diferencia estadisticamente significativa en la supervivencia a favor de los pacientes sintomaticos (p = 0,001). Conclusiones. Las MBC diagnosticadas incidentalmente se asociaron frecuentemente a otros tipos de progresion intracraneal, limitando las opciones terapeuticas.

  11. 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,…

  12. Assessing the Impact of a Race-Based Course on Counseling Students: A Quantitative Study

    Science.gov (United States)

    Paone, Tina R.; Malott, Krista M.; Barr, Jason J.

    2015-01-01

    This study sought to determine changes in 121 White counseling students following their participation in an experiential, race-based course taught in a group format. Pre- and postoutcomes were reported based on instruments that measured White racial identity development, White privilege, color blindness, and the costs of racism. Findings indicated…

  13. 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…

  14. Meta-Assessment in a Project-Based Systems Engineering Course

    Science.gov (United States)

    Wengrowicz, Niva; Dori, Yehudit Judy; Dori, Dov

    2017-01-01

    Project-based learning (PBL) facilitates significant learning, but it poses a major assessment challenge for assessing individual content knowledge. We developed and implemented an assessment approach and tool for a mandatory undergraduate systems engineering PBL-based course. We call this type of assessment "student-oriented"…

  15. 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…

  16. 南京铁心桥钢桥面热拌环氧混凝土铺装工艺研究%Hot-mixing Epoxy Asphalt Concrete Pavement Technology for Steel BridgeDeck Pavement of Tiexin Bridge in Nanjing City

    Institute of Scientific and Technical Information of China (English)

    潘军; 杨文

    2016-01-01

    Based on the steel bridge deck pavement engineering of Tiexin bridge in Nanjing city,the pavement technologies of hot mixing epoxy asphalt concrete using on steel deck were studied,inclu-ding the pavement structure design,mix design,pavement performance evaluation and construction technology.The difference of pavement construction between hot mixing and warm mixing epoxy as-phalt were also introduced in this paper.Research results show that hot mixing epoxy asphalt is suit-able for steel deck pavement due to its high stability,excellent high temperature performance and con-venient workability.%结合南京铁心桥钢桥面环氧铺装实体工程,对热拌环氧沥青混凝土铺装结构形式、热拌环氧沥青性能与混合料配合比设计、路用性能评价,以及施工工艺进行了系统研究,全面比较了热、温拌环氧沥青铺装施工工艺的区别。结果表明,热拌环氧沥青混凝土具有高强度、出色的高温稳定性,以及便捷的施工可操作性,非常适用于大跨钢桥铺装工程。

  17. Evaluation of medical students of teacher-based and student-based teaching methods in Infectious diseases course

    Science.gov (United States)

    Ghasemzadeh, I; Aghamolaei, T; Hosseini-Parandar, F

    2015-01-01

    Introduction: In recent years, medical education has changed dramatically and many medical schools in the world have been trying for expand modern training methods. Purpose of the research is to appraise the medical students of teacher-based and student-based teaching methods in Infectious diseases course, in the Medical School of Hormozgan Medical Sciences University. Methods: In this interventional study, a total of 52 medical scholars that used Section in this Infectious diseases course were included. About 50% of this course was presented by a teacher-based teaching method (lecture) and 50% by a student-based teaching method (problem-based learning). The satisfaction of students regarding these methods was assessed by a questionnaire and a test was used to measure their learning. information are examined with using SPSS 19 and paired t-test. Results: The satisfaction of students of student-based teaching method (problem-based learning) was more positive than their satisfaction of teacher-based teaching method (lecture).The mean score of students in teacher-based teaching method was 12.03 (SD=4.08) and in the student-based teaching method it was 15.50 (SD=4.26) and where is a considerable variation among them (p<0.001). Conclusion: The use of the student-based teaching method (problem-based learning) in comparison with the teacher-based teaching method (lecture) to present the Infectious diseases course led to the student satisfaction and provided additional learning opportunities.

  18. Ground Penetrating Radar Assessment of Flexible Road Pavement Degradation

    OpenAIRE

    Sandro Colagrande; Danilo Ranalli; Marco Tallini

    2011-01-01

    GPR investigations were used to study degraded road pavements built in cutting sections. Road integrity was assessed via quantitative analysis of power curves. 1600 MHz and 600 MHz radar sections were collected in 40 damaged and undamaged road pavement sites. The collected data were processed as follows: (i) linearisation with regression analysis of power curves; (ii) assessment of absorption angle α′ which is directly proportional to absorption coefficient α (this was obtained by setting t...

  19. Field environmental evaluation plan for sulfur use in pavements

    Science.gov (United States)

    Saylak, D.; Deuel, L. E.; Izatt, J. O.; Jacobs, C.; Zahray, R.; Ham, S.

    1982-07-01

    The use of sulfur in highway paving mixtures is discussed. The evaluation procedures deal with the safety and environmental aspects of storage and handling, formulation, construction, operation and maintenance of highway pavements containing sulfur, including the possible generation of noxious and abnoxious fumes, dust and gases. Methods and equipment for monitoring potential emissions and pollutants are recommended and safety practices for the handling of sulfur and sulfur-modified asphalt mixtures and pavements are discussed.

  20. Advanced Construction Material for Airfield Pavements and Rapid Runway Repair

    Science.gov (United States)

    1990-12-01

    AIRFIELD PAVEMENTS AND RAPID RUNWAY REPAIR by Vincent Maurice Saroni, B.S.C.E. and David W. Fowler, Ph.D., P.E. T. U. Taylor Professor in...to my family, Betsy and Mark. ADVANCED CONSTRUCTION MATERIAL FOR AIRFIELD PAVEMENTS AND RAPID RUNWAY REPAIR Vincent Maurice Saroni, B.S.C.E. THESIS...85 C.4 Calculation Results of Modulus of Rupture, Density and Percent Voids for Uncompacted Siliceous G ravel

  1. 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...

  2. Sensitivity analysis of longitudinal cracking on asphalt pavement using MEPDG in permafrost region

    Directory of Open Access Journals (Sweden)

    Chen Zhang

    2015-02-01

    Full Text Available Longitudinal cracking is one of the most important distresses of asphalt pavement in permafrost regions. The sensitivity analysis of design parameters for asphalt pavement can be used to study the influence of every parameter on longitudinal cracking, which can help optimizing the design of the pavement structure. In this study, 20 test sections of Qinghai–Tibet Highway were selected to conduct the sensitivity analysis of longitudinal cracking on material parameter based on Mechanistic-Empirical Pavement Design Guide (MEPDG and single factorial sensitivity analysis method. Some computer aided engineering (CAE simulation techniques, such as the Latin hypercube sampling (LHS technique and the multiple regression analysis are used as auxiliary means. Finally, the sensitivity spectrum of material parameter on longitudinal cracking was established. The result shows the multiple regression analysis can be used to determine the remarkable influence factor more efficiently and to process the qualitative analysis when applying the MEPDG software in sensitivity analysis of longitudinal cracking in permafrost regions. The effect weights of the three parameters on longitudinal cracking in descending order are air void, effective binder content and PG grade. The influence of air void on top layer is bigger than that on middle layer and bottom layer. The influence of effective asphalt content on top layer is bigger than that on middle layer and bottom layer, and the influence of bottom layer is slightly bigger than middle layer. The accumulated value of longitudinal cracking on middle layer and bottom layer in the design life would begin to increase when the design temperature of PG grade increased.

  3. The Efficiency Analysis of Low Impact Development Applied in Taiwan: A Case Study of Porous Pavement

    Science.gov (United States)

    Huang, Y. H.; Liu, H. J.; Hsu, N. S.; Chang, F. M.

    2014-12-01

    Low Impact Development (LID) has been developed since the end of 1990s. Lots of successful experience based on this new technology have been made. Taiwan Executive Yuan is conducting a six-year (2014~2019) program "Integrated River Basin Management Plan" applying LID to build sponge cities. Construction and Planning Agency, Ministry of the Interior is editing the manual of LID technology for Taiwan. However, since the hydrological environments, physiographic conditions, climates, the strength and frequency of disasters in Taiwan are different from that in America, this study takes the first laboratory experiment and model simulation to evaluate the efficiency of application of LID in Taiwan.LID Facilities includes porous pavement, rain garden, green roof, tree box filter facilities and so on, and in this study, porous pavement is taken as an example for discussion. In the part of laboratory experiments, the sand box experiments is designed to operate with the specified rainfall return period calculated by Horton formula and rainfall characteristics of Taipei. Then the outflow hydrograph in each designed rainfall of specified return period can be evaluated. As for model simulation, this study constructs LID simulation elements by SWMM model and tests the suitability for simulation of the outflow hydrograph obtained from experiments, and definitely quantifies the efficiency of water retention and flood reduction of porous pavement. The results fits well with the experimental observation data with less than 10% error of pick flow. It suggests that, with LID simulation elements constructed in this study, the efficiency of LID in actual on-site application can be evaluated.The results shows that porous pavement is able to delay arrival time of pick about 5% ~10% and reduce the pick flow about 5%~20%, and hold the ability of near 3~5% water retention. It proves that application of LID can retain water and reduce flood in Taiwan.

  4. The five-point bending test applied on wearing courses laid on orthotropic steel decks

    OpenAIRE

    Houel, Adrien; Arnaud, Laurent

    2009-01-01

    This paper deals with the evolving behaviour of wearing courses on steel orthotropic decks, such as the French Millau viaduct bituminous mix or an ultra high performance concrete (UHPC) pavement. This is of great importance when dealing with durability. A five-point bending fatigue test was developed since 2003 at the ENTPE laboratory. It enables to test various bituminous concrete mixes. Recent works on UHPC pavements on steel orthotropic decks are considered to improve service life of such ...

  5. Performance Prediction Modelling for Flexible Pavement on Low Volume Roads Using Multiple Linear Regression Analysis

    Directory of Open Access Journals (Sweden)

    C. Makendran

    2015-01-01

    Full Text Available Prediction models for low volume village roads in India are developed to evaluate the progression of different types of distress such as roughness, cracking, and potholes. Even though the Government of India is investing huge quantum of money on road construction every year, poor control over the quality of road construction and its subsequent maintenance is leading to the faster road deterioration. In this regard, it is essential that scientific maintenance procedures are to be evolved on the basis of performance of low volume flexible pavements. Considering the above, an attempt has been made in this research endeavor to develop prediction models to understand the progression of roughness, cracking, and potholes in flexible pavements exposed to least or nil routine maintenance. Distress data were collected from the low volume rural roads covering about 173 stretches spread across Tamil Nadu state in India. Based on the above collected data, distress prediction models have been developed using multiple linear regression analysis. Further, the models have been validated using independent field data. It can be concluded that the models developed in this study can serve as useful tools for the practicing engineers maintaining flexible pavements on low volume roads.

  6. Temporal evolution modeling of hydraulic and water quality performance of permeable pavements

    Science.gov (United States)

    Huang, Jian; He, Jianxun; Valeo, Caterina; Chu, Angus

    2016-02-01

    A mathematical model for predicting hydraulic and water quality performance in both the short- and long-term is proposed based on field measurements for three types of permeable pavements: porous asphalt (PA), porous concrete (PC), and permeable inter-locking concrete pavers (PICP). The model was applied to three field-scale test sites in Calgary, Alberta, Canada. The model performance was assessed in terms of hydraulic parameters including time to peak, peak flow and water balance and a water quality variable (the removal rate of total suspended solids). A total of 20 simulated storm events were used for model calibration and verification processes. The proposed model can simulate the outflow hydrographs with a coefficient of determination (R2) ranging from 0.762 to 0.907, and normalized root-mean-square deviation (NRMSD) ranging from 13.78% to 17.83%. Comparison of the time to peak flow, peak flow, runoff volume and TSS removal rates between the measured and modeled values in model verification phase had a maximum difference of 11%. The results demonstrate that the proposed model is capable of capturing the temporal dynamics of the pavement performance. Therefore, the model has great potential as a practical modeling tool for permeable pavement design and performance assessment.

  7. Pavement Response to Variable Tyre Pressure of Heavy Vehicles

    Directory of Open Access Journals (Sweden)

    Arshad Ahmad Kamil

    2016-01-01

    Full Text Available 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 R 20 tyre size and attached trailer with constant axle load. Measurements were made for actual tyre-pavement contact area. KENPAVE linear elastic program was then used to analyse the effects of the measured actual tyre-pavement contact area and the results was compared using conventional circular tyre contact area. A comparative analysis was then made between the actual contact area and the conventional circular tyre contact area. It was found that high tyre inflation pressure produce smaller contact area, giving more detrimental effect on the flexible pavement. It was also found that the temperature of tyres when the heavy vehicles are operational give less significant impact on tyre inflation pressure for the Malaysian climate.

  8. A comprehensive numerical analysis of the hydraulic behavior of a permeable pavement

    Science.gov (United States)

    Brunetti, Giuseppe; Šimůnek, Jiří; Piro, Patrizia

    2016-09-01

    The increasing frequency of flooding events in urban catchments related to an increase in impervious surfaces highlights the inadequacy of traditional urban drainage systems. Low Impact Development (LID) techniques have proven to be a viable and effective alternative by reducing stormwater runoff and increasing the infiltration and evapotranspiration capacity of urban areas. However, the lack of adequate modeling tools represents a barrier in designing and constructing such systems. This paper investigates the suitability of a mechanistic model, HYDRUS-1D, to correctly describe the hydraulic behavior of permeable pavement installed at the University of Calabria. Two different scenarios of describing the hydraulic behavior of the permeable pavement system were analyzed: the first one uses a single-porosity model for all layers of the permeable pavement; the second one uses a dual-porosity model for the base and sub-base layers. Measured and modeled month-long hydrographs were compared using the Nash-Sutcliffe efficiency (NSE) index. A Global Sensitivity Analysis (GSA) followed by a Monte Carlo filtering highlighted the influence of the wear layer on the hydraulic behavior of the pavement and identified the ranges of parameters generating behavioral solutions. Reduced ranges were then used in the calibration procedure conducted with the metaheuristic Particle swarm optimization (PSO) algorithm for the estimation of hydraulic parameters. The best fit value for the first scenario was NSE = 0.43; for the second scenario, it was NSE = 0.81, indicating that the dual-porosity approach is more appropriate for describing the variably-saturated flow in the base and sub-base layers. Estimated parameters were validated using an independent, month-long set of measurements, resulting in NSE values of 0.43 and 0.86 for the first and second scenarios, respectively. The improvement in correspondence between measured and modeled hydrographs confirmed the reliability of the

  9. 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.

  10. 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

  11. Evaluation of Asphalt Concrete Pavement Based on Passenger Ride Comfort Level%基于驾乘舒适性的沥青混凝土路面评价

    Institute of Scientific and Technical Information of China (English)

    王锋; 张金喜

    2014-01-01

    In order to provide a theoretical basis for the ride comfort level evaluation, daily management,and maintenance of asphalt concrete pavement,the performance parameters and three-directional acceleration data of highway pavements were measured indoors and outdoors. Using these data,the relationship between the mean square of weighted acceleration and the pavement performance was studied. A linear regression equation that reflects the relationship between the root mean square of weighed acceleration,speed,and roughness was obtained by fitting 214 groups of experimental data. In addition,the outdoor experimental results were verified using a driving simulator. The results show that the root mean square of weighed acceleration is strongly correlated with roughness,moderately correlated with the speed,and weakly correlated with the dynamic friction coefficient. Given a certain dynamic friction coefficient,the ride comfort level of an asphalt concrete pavement reduces with its roughness and driving speed increasing. When the roughness is 1. 35 and 3. 05 mm/m,the maximum speed with an appropriate ride comfort level is 124. 1 and 88. 7 km/h,respectively.%为给沥青混凝土路面舒适性评价及日常管理养护提供理论依据,在测得室内外大量道路路面性能参数及三向加速度数据的基础上,研究了加权加速度均方根值与道路路面性能参数之间的关系.运用214组有效室外实验数据,拟合了加权加速度均方根、行驶速度与平整度关系的线性回归方程,并用驾驶模拟舱对室外实验结论进行了验证.结果表明:加权加速度均方根与平整度强相关,与速度中等程度相关,与动态摩擦系数弱相关,在动态摩擦系数一定的条件下,驾乘舒适性随平整度及行驶速度的增加而降低;当平整度为1.35和3.05 mm/m时,满足驾乘舒适性的最大速度分别为124.1和88.7 km/h.

  12. Librarian involvement in a nutrition undergraduate research course: preparing nutrition students for evidence-based practice.

    Science.gov (United States)

    Smith, Susan C; Penumetcha, Meera

    2010-01-01

    Given the foundational importance of literature searching skills to later stages of research and, ultimately, evidence-based practice, the authors wanted to assess a unique strategy for teaching such skills. This pilot study describes the results of an undergraduate nutrition research course in which a librarian lead several class sessions. The goal of this study was to assess students' perceptions, attitudes and use of research literature and resources before and after a course partially taught by a librarian. Twenty-seven students enrolled in an undergraduate Introduction to Research course at Georgia State University were given pre- and post-test questionnaires at the beginning and end of a course that included three librarian-led class sessions. Most of the results indicate that the repeated involvement of a librarian enriched this particular undergraduate research course. By the end of the course, students were more comfortable in libraries and with using library resources; they used the campus library more frequently; they were more confident in their ability to find high-quality information on nutrition-related topics and identify strengths and weaknesses of different information sources; and they felt they gained skills that will help them achieve their educational and career goals.

  13. 重载交通下不同基层类型沥青路面结构应力分析%Analysis for Structural Stress of Asphalt Pavement of Different Types of Basecourses under Heavy Load Traffic

    Institute of Scientific and Technical Information of China (English)

    伍祥松

    2012-01-01

    基于我国沥青路面设计理论及标准,参考实际沥青路面结构,选取不同的沥青路面结构与材料参数,如结构层厚度、模量和泊松比等,采用BISAR3.0路面力学计算程序计算分析不同基层类型对沥青混凝土路面结构内部应力状态的影响.结果表明,柔性基层路面与半刚性基层路面的破坏机理存在明显差异,为了实现2种路面的优势互补,应将柔性基层与半刚性基层的结构进行合理的优化组合,以弥补柔性基层和半刚性基层沥青路面的缺陷.%Based on design theories and standards for asphalt pavement in China and by reference to actual structures of asphalt pavement, this paper selects different structure and material parameters of asphalt pavement, such as thickness, modulus and Poisson' s Ratio of structural layers, etc. , calculates and analyzes influences of different basecourse types on internal stress states of asphalt concrete pavement structures by means of BISAR3. 0 mechanical calculation program for pavement. The results show that significant differences exist in failure mechanisms of flexible basecourse pavement and semi - rigid basecourse pavement, to realize complementary advantages of two pavements, the structures of flexible basecourse and semi - rigid basecourse should be optimized and combined in a reasonable way to make up defects of flexible basecourse and semi - rigid basecourse pavements.

  14. Expeditionary Readiness Training (ExpeRT) Course Expansion Final Environmental Assessment Creech Air Force Base

    Science.gov (United States)

    2006-07-01

    surface. Desert pavement is common to arid environments and acts as a shell to softer, more vulnerable soils below. Lenses of caliche (sediment...communities are the most common vegetation communities on the South Range and SFA. Where soils are especially alkaline and clay-rich, as on the margins of...whitebursage. Saltbush species, ephedras (Ephedra spp.), brittlebush (Enceliavirginensis), desert mallow (Sphaeralcea ambigua), cacti (especially

  15. Simulation Study of Rainwater Infiltration on Permeable Asphalt Pavement%透水性沥青路面雨水入渗模拟研究

    Institute of Scientific and Technical Information of China (English)

    黄小兰; 熊俊; 黄敏; 喻超

    2011-01-01

    Permeable asphalt pavement becomes the important trend of pavement development due to its many advantages such as rapid drainage,skid resistance,rain mist reduction,reflection reduction and noise reduction.In this paper,the paving characteristics of permeable asphalt pavement are discussed.Based on the structural characteristics of permeable asphalt pavement applied in Japan,water head distribution for permeable asphalt pavement and common dense-graded asphalt pavement under rainfall are separately analyzed through numerical simulation,and thus the drainage ability of permeable asphalt pavement under strong rainfall is studied.%透水性沥青路面由于具有迅速排水、抗滑、降低雨天水雾、减少雨后反光、降低噪声等许多优点,而成为道路路面发展的重要方向。讨论了透水性沥青路面在铺装结构上的特点,并基于日本使用的透水性沥青路面结构特征,通过数值模拟,对比分析了降雨条件下透水性沥青路面与普通密级配沥青路面的水头分布变化情况,研究了透水性沥青路面在强降雨期的排水性能。

  16. Assessing the Effectiveness of an Evidence-based Practice Pharmacology Course Using the Fresno Test.

    Science.gov (United States)

    Gardner, Alice; Lahoz, Monina R; Bond, Irena; Levin, Len

    2016-09-25

    Objective. To assess the effectiveness of an evidence-based practice (EBP) pharmacology elective course to teach EBP skills using the Fresno Test (FT). Methods. Pharmacy faculty members and medical librarians developed the elective course and offered it to two cohorts of doctor of pharmacy (PharmD) students. A pre/post intervention study design was used. Seven of 12 FT items were chosen to measure specific EBP skills: Ask, Access, Appraise and Apply. Pre/postcomposite and FT item mean scores were compared using Student's t test with p<0.05 set as significant a priori. Results. Composite FT mean scores increased significantly for both cohorts. Mean scores for both cohorts increased significantly in four of the seven FT items but on different FT items. Conclusion. As a profession that commonly uses evidence-based guidelines, developing and integrating an EBP course in the PharmD curriculum is worth considering.

  17. 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 ...

  18. 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.

  19. Librarian-facilitated problem-based learning course in a school of dental medicine.

    Science.gov (United States)

    Hasman, Linda

    2012-01-01

    While problem-based learning has been used in medical practice for several decades, dental education was slower to adapt this education model. However, as dental curricula are embracing this pedagogy, dental and other health sciences librarians are in a position to provide important curricular support. This article will detail one dental liaison librarian's experience with facilitating a problem-based, case-based studies course within the curriculum of a dental school.

  20. The Drift Chambers Handbook, introductory laboratory course (based on, and adapted from, A H Walenta's course notes)

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Ix-B GarcIa [Escuela de Ciencias FIsico-Matematicas ' Luis Manuel Rivera Gutierrez' , U.M.S.N.H (Mexico); Herrera, J GarcIa [Centro de Instrumentacion ICFA Morelia, U.M.S.N.H (Mexico); Villasenor, L [Instituto de Fisica y Matematicas. U.M.S.N.H (Mexico)

    2005-01-01

    This handbook was written for the Drift Chambers introductory laboratory course to be held at 11th Mexican School of Particles and Fields that will be held at the Universidad Veracruzana on the campus of the University at Xalapa, Veracruz, Mexico. This course intends to introduce drift chambers, which play an important role in particle physics experiments as tracking detectors. We start such laboratory course with a brief review of the physics theoretical background. The experimental setup consists of a single-sided, single-cell drift chamber, a plastic scintillator detector, the standard P-10 gas mixture (90% Ar, 10% CH{sub 4}) and a collimated {sup 90}Sr source. The measurements on the drift velocity of electrons, its change as a function of a drift field, gas gain and diffusion are performed at this laboratory course.

  1. 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.

  2. Accuracy improvement capability of advanced projectile based on course correction fuze concept.

    Science.gov (United States)

    Elsaadany, Ahmed; Wen-jun, Yi

    2014-01-01

    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.

  3. 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

  4. 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…

  5. 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

  6. Update to Permeable Pavement Research at the Edison Environmental Center - proceedings

    Science.gov (United States)

    The EPA’s Urban Watershed Management Branch (UWMB) has been monitoring the permeable pavement demonstration site at the Edison Environmental Center, NJ since 2010. This site has three different types of permeable pavements including interlocking concrete permeable pavers, p...

  7. 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…

  8. Designing and Implementing a Hands-On, Inquiry-Based Molecular Biology Course

    Science.gov (United States)

    Regassa, Laura B.; Morrison-Shetlar, Alison I.

    2007-01-01

    Inquiry-based learning was used to enhance an undergraduate molecular biology course at Georgia Southern University, a primarily undergraduate institution in rural southeast Georgia. The goal was to use a long-term, in-class project to accelerate higher-order thinking, thereby enabling students to problem solve and apply their knowledge to novel…

  9. 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).…

  10. 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…

  11. 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…

  12. 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…

  13. How are "teaching the teachers" courses in evidence based medicine evaluated? A systematic review

    NARCIS (Netherlands)

    Walczak, J.; Kaleta, A.; Gabrys, E.; Kloc, K.; Thangaratinam, S.; Barnfield, G.; Weinbrenner, S.; Meyerrose, B.; Arvanitis, T.N.; Horvath, A.R.; Zanrei, G.; Kunz, R.; Suter, K.; Burnand, B.; Arditi, C.; Oude Rengerink, K.; Harry, G.; Mol, B.W.J.; Khan, K.S.

    2010-01-01

    ABSTRACT: BACKGROUND: Teaching of evidence-based medicine (EBM) has become widespread in medical education. Teaching the teachers (TTT) courses address the increased teaching demand and the need to improve effectiveness of EBM teaching. We conducted a systematic review of assessment tools for EBM TT

  14. Investigating the Use of a Digital Library in an Inquiry-Based Undergraduate Geology Course

    Science.gov (United States)

    Apedoe, Xornam S.

    2007-01-01

    This paper reports the findings of a qualitative research study designed to investigate the opportunities and obstacles presented by a digital library for supporting teaching and learning in an inquiry-based undergraduate geology course. Data for this study included classroom observations and field-notes of classroom practices, questionnaires, and…

  15. 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…

  16. 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…

  17. Distributed Collaborative Homework Activities in a Problem-Based Usability Engineering Course

    Science.gov (United States)

    Carroll, John M.; Jiang, Hao; Borge, Marcela

    2015-01-01

    Teams of students in an upper-division undergraduate Usability Engineering course used a collaborative environment to carry out a series of three distributed collaborative homework assignments. Assignments were case-based analyses structured using a jigsaw design; students were provided a collaborative software environment and introduced to a…

  18. 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…

  19. Student Satisfaction with Blended and Online Courses Based on Personality Type

    Science.gov (United States)

    Bolliger, Doris U.; Erichsen, Elizabeth Anne

    2013-01-01

    The purpose of the study was to investigate differences in perceived student satisfaction in blended and online learning environments based on personality type. A total of 72 graduate students enrolled in blended and online courses at two research universities in the United States completed an abbreviated online version of the Myers-Briggs Type…

  20. Evaluating a Web-based Graduate Level Nursing Ethics Course: Thumbs Up or Thumbs Down?

    Science.gov (United States)

    McAlpine, Heather; Lockerbie, Linda; Ramsay, Deyanne; Beaman, Sue

    2002-01-01

    Student and teacher opinions were obtained regarding a Web-based ethics course for nursing graduate students. Both groups had positive views of online discussions; critical and reflective thinking was enhanced; technical difficulties were overcome with the help of expert support services; compressed time frame was a drawback; and ways to enhance…

  1. Adapting Scenario-Based Curriculum Materials to Community College Technical Courses

    Science.gov (United States)

    Yarnall, Louise; Toyama, Yukie; Gong, Bowyee; Ayers, Catherine; Ostrander, Jane

    2007-01-01

    Community college educators seek to infuse their workforce courses with more "real world" activities. This 3-year case study examined how 7 instructors and 78 students in California and Texas responded to the changes involved in implementing one type of reform program--the scenario-based curriculum (Schank, 1997). The study shows that…

  2. A Survey of Knowledge Management Skills Acquisition in an Online Team-Based Distributed Computing Course

    Science.gov (United States)

    Thomas, Jennifer D. E.

    2007-01-01

    This paper investigates students' perceptions of their acquisition of knowledge management skills, namely thinking and team-building skills, resulting from the integration of various resources and technologies into an entirely team-based, online upper level distributed computing (DC) information systems (IS) course. Results seem to indicate that…

  3. 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…

  4. 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.

  5. Performance-Based Assessment in an Online Course: Comparing Different Types of Information Literacy Instruction

    Science.gov (United States)

    Mery, Yvonne; Newby, Jill; Peng, Ke

    2012-01-01

    This study investigates whether the type of instruction (a single face-to-face librarian-led instruction, instructor-led instruction, or an online IL course--the Online Research Lab) has an impact on student information literacy gains in a Freshman English Composition program. A performance-based assessment was carried out by analyzing…

  6. 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…

  7. Conversations about Curriculum Change: Mathematical Thinking and Team-Based Learning in a Discrete Mathematics Course

    Science.gov (United States)

    Paterson, Judy; Sneddon, Jamie

    2011-01-01

    This article reports on the learning conversations between a mathematician and a mathematics educator as they worked together to change the delivery model of a third year discrete mathematics course from a traditional lecture mode to team-based learning (TBL). This change prompted the mathematician to create team tasks which increasingly focused…

  8. 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…

  9. A Field-Based Introductory Physical and Historical Geology Course Taught in the Rocky Mountains.

    Science.gov (United States)

    Stephens, George Christopher; And Others

    1987-01-01

    Describes a six-week, six-credit, field-based physical and historical geology course offered by Lehigh University (Pennsylvania) in conjunction with its standard summer field studies program. Stresses the advantages of integrating physical and historical geology concepts in a field setting. (TW)

  10. 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

  11. Fundraising Strategies Developed by MBA Students in Project-Based Learning Courses

    Science.gov (United States)

    Arantes do Amaral, Joao Alberto; Petroni, Liége Mariel; Hess, Aurélio

    2016-01-01

    The ability to raise funds is a skill that most modern project managers need. While a good deal of literature exists on the strategies NGOs employ to raise funds for their operations, less attention has been paid to the strategies used by students involved in Project-Based Learning courses that often partner with NGOs. Fundraising is an important…

  12. Campus Clinical: simulation-based curriculum designed to meet clinical course learning outcomes.

    Science.gov (United States)

    Jarvis, Michelle; Rivers, Julie

    2014-01-01

    Campus Clinical is a simulation-based curriculum designed to meet the challenge of decreasing clinical spaces in maternal-child units. The curriculum framework is situated in a constructivist, experiential learning context, integrating Chickering and Gamson's principles for good practice in education. This innovative approach to meeting clinical course learning outcomes is transferable to a variety of settings.

  13. A Modeling-Based College Algebra Course and Its Effect on Student Achievement

    Science.gov (United States)

    Ellington, Aimee J.

    2005-01-01

    In Fall 2004, Virginia Commonwealth University (VCU) piloted a modeling-based approach to college algebra. This paper describes the course and an assessment that was conducted to determine the effect of this approach on student achievement in comparison to a traditional approach to college algebra. The results show that compared with their…

  14. 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

  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. Classroom Action Research on Formative Assessment in a Context-Based Chemistry Course

    Science.gov (United States)

    Vogelzang, Johannes; Admiraal, Wilfried F.

    2017-01-01

    Context-based science courses stimulate students to reconstruct the information presented by connecting to their prior knowledge and experiences. However, students need support. Formative assessments inform both teacher and students about students' knowledge deficiencies and misconceptions and how students can be supported. Research on formative…

  17. 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…

  18. Effectiveness of Inquiry-Based Learning in an Undergraduate Exercise Physiology Course

    Science.gov (United States)

    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 (individual subject-specific tests and group interviews)…

  19. The Imagery of Rhetoric: Film and Academic Writing in the Discipline-based ESL Course.

    Science.gov (United States)

    Kasper, Loretta F.

    2000-01-01

    Describes three reading/writing lessons on the topics of linguistics, environmental science, and anthropology used in a discipline-based college-level English as a second language course to illustrate how to use film to teach academic writing skills. Discusses how students analyze a film to help articulate the content of an essay or a book. (SR)

  20. A Role-Playing Virtual World for Web-Based Application Courses

    Science.gov (United States)

    Depradine, Colin

    2007-01-01

    With the rapid development of the information communication and technology (ICT) infrastructure in the Caribbean, there is an increasing demand for skilled software developers to meet the ICT needs of the region. Consequently, the web-based applications course offered at the University of the West Indies, has been redeveloped. One major part of…

  1. Effects of Multidimensional Concept Maps on Fourth Graders' Learning in Web-Based Computer Course

    Science.gov (United States)

    Huang, Hwa-Shan; Chiou, Chei-Chang; Chiang, Heien-Kun; Lai, Sung-Hsi; Huang, Chiun-Yen; Chou, Yin-Yu

    2012-01-01

    This study explores the effect of multidimensional concept mapping instruction on students' learning performance in a web-based computer course. The subjects consisted of 103 fourth graders from an elementary school in central Taiwan. They were divided into three groups: multidimensional concept map (MCM) instruction group, Novak concept map (NCM)…

  2. 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…

  3. Using SAS/IntrNet for Evaluating Web-Based Courses.

    Science.gov (United States)

    Yu, Chong-ho; Jannasch-Pennell, Angel; Digangi, Sam; Wasson, Barnaby

    1998-01-01

    Describes the use of SAS/IntrNet, a Web service rather than a Web server, to evaluate and enhance university level Web-based courses. IntrNet provides the ability to create both static and dynamic Web pages, using Web publishing tools to convert SAS output to hypertext markup language for the creation of static Web pages. (Author/LRW)

  4. Laboratory evaluation of durability of open-graded friction course Mixtures

    Directory of Open Access Journals (Sweden)

    N. A. Qureshi

    2015-06-01

    Full Text Available Open-graded friction courses (OGFC are special purpose thin surface mixtures of hot mix asphalt (HMA pavement that is increasingly being used around the world. Owing to its safety aspects, OGFC is being regularly used as final riding surface on interstate and high speed expressways by different highway agencies in United States, including Alabama Department of Transportation. OGFC pavements in Alabama are facing premature failure due to different reasons. Loss of durability and functionality causes failure of OGFC pavements. Thus, research is needed to improve the durability of OGFC and enhance its beneficial properties. This research proposes methods to improve the durability of OGFC mixtures through laboratory performance testing. Aggregate gradation and layer thickness significantly affected the durability of the OGFC surfaces in general, especially the layer thickness. The Hamburg test indicated a 50-60% higher resistance to moisture damage of OGFC pavement with increase in thickness from 19 mm to 38 mm. The Cantabro stone loss of OGFC pavements is reduced 10- 50% with increase in thickness from 19 mm to 38 mm. The permeability tests results indicated 12-100% increase in permeability with increase in thickness of OGFC pavement from 19 mm to 38 mm. Indirect tensile strength tests indicated 50-300% increase in strength with increase in thickness of OGFC pavement from 19 mm to 38 mm.

  5. On-site inspections of pavement damages evolution using GPR

    Science.gov (United States)

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

    2014-05-01

    Ground-penetrating radar (GPR) is being increasingly used for pavements maintenance due to the wide range of applications spanning from physical to geometrical inspections, thereby allowing for a reliable diagnosis of the main causes of road structural damages. In this work, an off-ground GPR system was used to investigate a large-scale rural road network. Two sets of surveys were carried out in different time periods, with the main goals to i) localize the most critical sections; ii) monitor the evolution of previous damages and localize newborn deep faults, although not revealed at the pavement surface level; iii) analyze the causes of both evolution and emergence of faults by considering environmental and human factors. A 1-GHz GPR air-launched antenna was linked to an instrumented van for collecting data at traffic speed. Other support techniques (e.g. GPS data logger, odometer, HD video camera) were used for cross-checking,. Such centre frequency of investigation along with a 25-ns time window allow for a signal penetration of 900 mm, consistent with the deepest layer interfaces. The bottom of the array was 400 mm over the surface, with a minimum distance of 1200 mm from the van body. Scan length of maximum 10 km were provided for avoiding heavy computational loads. The rural road network was located in the District of Rieti, 100 km north from Rome, Italy, and mostly develops in a hilly and mountainous landscape. In most of the investigated roads, the carriageway consists in two lanes of 3.75 meters wide and two shoulders of 0.50 meters wide. A typical road section includes a HMA layer (65 mm average thickness), a base layer (100 mm average thickness), and a subbase layer (300 mm average thickness), as described by pavement design charts. The first set of surveys was carried out in two days at the beginning of spring in moderately dry conditions. Overall, 320-km-long inspections were performed in both travel directions, thereby showing a productivity of

  6. Teaching Effectiveness of Integrating Task-based Approach into Inorganic and Analytical Chemistry Course

    Institute of Scientific and Technical Information of China (English)

    Tianjiao; WEI; Yiru; WANG; Sen; HUANG

    2013-01-01

    From the perspective of students,the effectiveness of task-based approach in In-organic and Analytical Chemistry course were summarized.The strength and weak points of TBA were analyzed,and the specific suggestions for obtaining better effect were put forward.The result showed a satisfactory achievement and unexpected result in showing the effectiveness of this teaching model.Not only could this TBA enhance student’s overall knowledge of discipline but also cultivate students’ multi-dimensional competence:competence in searching literatures, communication and management,autonomous,co-operative and reflective learning,and competence in analyzing and problem-solving,as well as improving their language expression ability,and skills in using multi-media and internet technology into their academic course learning and research.The implication of this research on the classroom teaching practice will shed light on the future teaching reform of other courses in China.

  7. Introducing problem-based learning to undergraduate IT service management course: student satisfaction and work performance

    Directory of Open Access Journals (Sweden)

    Katarina Pažur Aničić

    2016-12-01

    Full Text Available This paper describes the implementation of problem-based learning (PBL principles in an undergraduate IT service management course, followed by the results about student satisfaction and work performance. The results indicate the students’ general satisfaction with the course implementation, as well as some challenges regarding the self-assessment and peer assessment of their work. The findings also reveal the students’ better work performance in project results than in traditional knowledge tests, which reinforces the indications about their positive attitudes towards the interactive PBL environment. The cluster analyses identified seven different patterns in student behaviour regarding course performance. The presented results can be considered a new aspect of the development and amendment of the information and communication technology (ICT skills requested by future employers. In this regard, the demand for innovation in the education of future ICT professionals arises from the need for experts equipped with both IT and business skills.

  8. Laboratory projects using inquiry-based learning: an application to a practical inorganic course

    Directory of Open Access Journals (Sweden)

    José G. Carriazo

    2011-01-01

    Full Text Available This paper reports how laboratory projects (LP coupled to inquiry-based learning (IBL were implemented in a practical inorganic chemistry course. Several coordination compounds have been successfully synthesised by students according to the proposed topics by the LP-IBL junction, and the chemistry of a number of metals has been studied. Qualitative data were collected from written reports, oral presentations, lab-notebook reviews and personal discussions with the students through an experimental course with undergraduate second-year students at the Universidad Nacional de Colombia during the last 5 years. Positive skills production was observed by combining LP and IBL. Conceptual, practical, interpretational, constructional (questions, explanations, hypotheses, communicational, environmental and application abilities were revealed by the students throughout the experimental course.

  9. Problems in Problem-Based Learning - Experiences, Analysis and Lessons Learned on an Introductory Programming Course

    Directory of Open Access Journals (Sweden)

    Päivi KINNUNEN

    2005-10-01

    Full Text Available We have applied Problem-Based Learning (PBL on an introductory programming course for several years with positive results. In this paper we present the outcomes and discuss our experiences of applying a modified version of PBL such that needs less tutoring resources and could better be used in large-scale courses, too. PBL has many positive effects on studying: Students report that they liked the social aspect of studying in a group. Generally students appreciated the possibility to be active participants in a course. On the other hand, group dynamic difficulties, tolerance of uncertainty and demanding studying skills caused problems that were too hard to overcome to some students. In this paper we introduce different versions of PBL, discuss efficiently and inefficiently working PBL groups and present their characters. We also discuss the possible reasons for differently working groups. Finally, we give some suggestions for interventions that might help the PBL groups to work better.

  10. Respirable crystalline silica exposures during asphalt pavement milling at eleven highway construction sites.

    Science.gov (United States)

    Hammond, Duane R; Shulman, Stanley A; Echt, Alan S

    2016-07-01

    Asphalt pavement milling machines use a rotating cutter drum to remove the deteriorated road surface for recycling. The removal of the road surface has the potential to release respirable crystalline silica, to which workers can be exposed. This article describes an evaluation of respirable crystalline silica exposures to the operator and ground worker from two different half-lane and larger asphalt pavement milling machines that had ventilation dust controls and water-sprays designed and installed by the manufacturers. Manufacturer A completed milling for 11 days at 4 highway construction sites in Wisconsin, and Manufacturer B completed milling for 10 days at 7 highway construction sites in Indiana. To evaluate the dust controls, full-shift personal breathing zone air samples were collected from an operator and ground worker during the course of normal employee work activities of asphalt pavement milling at 11 different sites. Forty-two personal breathing zone air samples were collected over 21 days (sampling on an operator and ground worker each day). All samples were below 50 µg/m(3) for respirable crystalline silica, the National Institute for Occupational Safety and Health recommended exposure limit. The geometric mean personal breathing zone air sample was 6.2 µg/m(3) for the operator and 6.1 µg/m(3) for the ground worker for the Manufacturer A milling machine. The geometric mean personal breathing zone air sample was 4.2 µg/m(3) for the operator and 9.0 µg/m(3) for the ground worker for the Manufacturer B milling machine. In addition, upper 95% confidence limits for the mean exposure for each occupation were well below 50 µg/m(3) for both studies. The silica content in the bulk asphalt material being milled ranged from 7-23% silica for roads milled by Manufacturer A and from 5-12% silica for roads milled by Manufacturer B. The results indicate that engineering controls consisting of ventilation controls in combination with water-sprays are

  11. A Comparison of Interaction in AV-based and Internet-based Distance Courses

    Directory of Open Access Journals (Sweden)

    Melodee Landis

    2001-04-01

    Full Text Available At the center of the debate over the viability of distance education is whether the newer electronic technologies can offer enough interaction to maintain quality learner outcomes and critical mass. Two of the most commonly used forms of distance education are 1 two-way, fully interactive audio-video classrooms and 2 on-line instruction through the Internet or Worldwide Web. This study used qualitative methods to compare and contrast the interaction that occurred in distance learning courses offered via each medium. The research process confirmed findings that there were fundamental differences in the interaction that occurred in the two environments. On-line interaction is so profoundly different than interaction in the traditional and AV-based class room that it appears instructors and students will need a substantial period of adjustment to feel comfortable with it and to fully appreciate its value. It appears that, as distance teaching and learning moves to a “mixed media” approach to teaching and learning, how interaction is handled with each of the media may be important to the success of a distance program.

  12. Design and construction of tunnel pavement on Guangxi highway%广西高速公路隧道路面的设计与施工

    Institute of Scientific and Technical Information of China (English)

    肖锋

    2011-01-01

    介绍了广西高速公路隧道中所采用的基于永久性路面或长寿命设计理念的隧道路面结构形式,以及隧道路面中所采用的新结构、新材料与新工艺;并对连续配筋混凝土路面结构层的设计与施工进行了简要介绍,对今后同类隧道路面施工具有一定指导意义。%This thesis introduces the tunnel pavement structure form on Guangxi highway tunnel based on eternal pavement and long life design concept, and new structure, new material, and new technology used in tunnel pavement as well, and briefly expounds the design and construction of continuous reinforcement concrete pavement structure, which has certain guiding significance for future similar tunnel pavement construction.

  13. Gender Differences in Achievement in an Inquiry-Based Learning Precalculus Course

    OpenAIRE

    Thomas E. Cooper; Brad Bailey; Karen S. Briggs

    2015-01-01

    The authors conducted a two-semester quasi-experimental study in which each author taught a traditional lecture-based section of precalculus and a section using an inquiry-based approach called a Modified Moore Method in which the students worked through and presented the course material. A common final exam was used to compare student achievement. The results were compared for the overall population and by each instructor. Gender proved to be an important variable with the females performing...

  14. Engineering and Design: Use of Petroleum Contaminated Soil in Cold-Mix Asphalt Stabilized Base Course

    Science.gov (United States)

    2007-11-02

    and construction of mixtures using petroleum contaminated soil and similar hydrocarbon waste for cold -mix asphalt stabilized base course (ASB). This...also performed an analysis using the diesel contaminated soil as part of a cold mix asphalt mixture . The mixtures produced with and without contaminated...quality materials ( RAP and asphalt cement) and good mixture design, construction procedures, and quality control, a high quality base or intermediate

  15. The Prediction of Fatigue Life Based on Four Point Bending Test

    NARCIS (Netherlands)

    Pramesti, F.P.; Molenaar, A.A.A.; Van de Ven, M.F.C.

    2013-01-01

    To be able to devise optimum strategies for maintenance and rehabilitation, it is essential to formulate an accurate prediction of pavement life and its maintenance needs. One of the pavement life prediction methods is based on the pavement's capability to sustain fatigue. If it were possible to hav

  16. 高模量沥青面层合理结构形式的有限元研究%Definite Element Study on Reasonable Structure Form of High Modulus Asphalt Pavement

    Institute of Scientific and Technical Information of China (English)

    王先伟

    2012-01-01

    本文根据以往的经验提出了三种高模量沥青路面的结构形式,并从应力、应变和弯沉值的角度对高模量沥青面层结构进行分析,从而得出了高模量沥青混凝土路面的合理结构形式,为相关的沥青路面设计提供了一个新的分析方法。%This article provides three type of high modulus asphalt pavement structure form based on previous experience. It analyses high modulus asphalt pavement structure form from stress, strain and deflection value. A reasonable structure form of high modulus asphalt pavement is given, which also provides a new method to design asphalt pavement.

  17. The effect of Cryogenic Crumb Rubber in cold recycled mixes for road pavements

    DEFF Research Database (Denmark)

    Pettinari, Matteo; Dondi, Giulio; Sangiorgi, Cesare

    2014-01-01

    of cold recycled mixes for road bases is considerable. Furthermore, new products are continuously being introduced or developed for recycling purposes. The objective of this research project was to test the effects, both mechanically and environmentally, of crumb rubber included in 100% Reclaimed Asphalt...... Pavement cold mixes for road bases, bound with bitumen emulsion and cement. The crumb rubber is produced cryogenically with granulometric selection, which together with the bitumen, the cement and the fine fractions of the mix forms a resilient mastic capable of imparting significant fatigue resistance...

  18. Design and Development of a Sample "Computer Programming" Course Tool via Story-Based E-Learning Approach

    Science.gov (United States)

    Kose, Utku; Koc, Durmus; Yucesoy, Suleyman Anil

    2013-01-01

    This study introduces a story-based e-learning oriented course tool that was designed and developed for using within "computer programming" courses. With this tool, students can easily adapt themselves to the subjects in the context of computer programming principles, thanks to the story-based, interactive processes. By using visually…

  19. Research on application urban road pervious pavement based on the concept of sponge city%基于海绵城市理念的透水性城市道路路面应用研究

    Institute of Scientific and Technical Information of China (English)

    何定举; 王世槐; 高亚雄; 王文奇; 王宠惠

    2015-01-01

    In order to solve drainage and water storage on urban roads,the paper researches the importance of constructing the sponge city and water permeability asphalt pavement,analyzes the water permeability roadbed structure scheme,explores the application of the roadbed struc-ture,and points out the roadbed has evident environmental and social benefits,so it has better application future.%为了解决城市道路排水和储水问题,研究了建设海绵城市的意义及透水性沥青路面的应用意义,并对透水性路面结构方案进行了分析,探索了该路面结构的应用前景等,指出透水性沥青路面环境和社会效益突出,推广应用前景良好。

  20. 基于公路沥青面层的碎石针状颗粒超量分析%On overfilling analysis of gravel needle-shaped particles based on asphalt pavement of roads

    Institute of Scientific and Technical Information of China (English)

    薛艳霞

    2015-01-01

    The paper illustrates the quality demands for the concrete asphalt layer on the gravels,introduces the basic procedure for the manufac-turing of the gravel materials,and analyzes the reasons for the higher contents of the needle-shaped particles in gravels,and points out the effec-tive measures to control the particles contents,so as to ensure the construction quality of the asphalt pavement of roads.%阐述了混凝土沥青面层对碎石的质量要求,介绍了碎石集料生产工艺的基本流程,从原材料、喂料、加工工艺等方面入手,分析了碎石针片状颗粒含量偏高的原因,并提出了控制针状碎石含量的有效措施,从而保证公路沥青面层的施工质量。

  1. 基于仿生色彩对福建高校校园铺地色彩设计的探讨%Discussion about Pavement Color Design in Fujian University Campus based on Bionic Color

    Institute of Scientific and Technical Information of China (English)

    刘仁芳

    2013-01-01

    The colors of University Campus have important significance for inheriting campus culture and building a harmonious environment. After practice investigation and research, the article discusses discussed the application of bionic color in the pavementcolor design of Fujian university campus, put forward that biological color image and its style can be used in the pavement color design of Fujian university campus after been scientific integrated and designed.%  高校校园色彩对传承校园文化,营造和谐校园环境具有重要意义。通过调查研究,探讨仿生色彩在福建高校校园铺地色彩设计中的应用,并提出把生物色彩形象和生物色彩形式经过科学的整合与设计应用到福建高校校园铺地色彩设计当中。

  2. 钢桥面沥青铺装层设计要点分析%Analysis of the Notes about Design of the Steel Bridge Asphalt Pavement

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      本文根据笔者多年的工作经验,从钢桥面沥青铺装设计的技术要求、桥面沥青铺层的结构和大跨径钢桥面沥青铺装三个方面,探讨了钢桥面沥青铺装层的设计要点。%In this article bases on years of work experience, discusses the design points of steel bridge asphalt pavement fr-om three aspects of the technical requirements of steel bridge asphalt pavement design, the structure of bridge asphalt over-lay and the large span steel bridge asphalt pavement.

  3. Acoustical estimation of parameters of porous road pavement

    Science.gov (United States)

    Valyaev, V. Yu.; Shanin, A. V.

    2012-11-01

    In the simplest case, porous road pavement of a known thickness is described by such parameters as porosity, tortuosity, and flow resistance. The problem of estimating these parameters is investigated in this paper. An acoustic signal reflected by the pavement is used for this. It is shown that this problem can be solved by an experiment conducted in the time domain (i.e., the pulse response of the media is recorded). The incident sound wave is thrown at a grazing angle to the surface between the pavement and the air to improve penetration into the porous medium. The procedure of computing of the pulse response using the Morse-Ingard model is described in detail.

  4. A Web-Based Chemistry Course as a Means To Foster Freshmen Learning

    Science.gov (United States)

    Dori, Yehudit Judy; Barak, Miri; Adir, Noam

    2003-09-01

    Chemistry courses in higher education have traditionally been composed of lectures, problem solving sessions, and laboratories. This study describes a Web-based chemistry course and the learning outcomes of freshmen that used it. Chemistry faculty and teaching assistants were interviewed regarding their views about Web-based teaching and learning. Students who took part in a Web-based general chemistry course were divided into two groups based on their preference of participating in a Computerized Molecular Modeling (CMM) project. The experimental group students carried out an individualized project using CMM software to represent a complex molecule in three model types, compute its molecular weight, and construct hybridization and electrical charge distribution for each of the carbon atoms in the molecule. Pre- and post-tests along with final examination grades served for assessing the students' achievements. The 95 experimental students achieved significantly higher grades than their 120 control-group peers in both the post-test and the final examination. The experimental students were able to switch from 1-D to 2- and 3-D molecular representations, argue for selecting an appropriate substance for a particular purpose, and transfer between the four levels of understanding in chemistry better than their control counterparts.

  5. Geo synthetic-reinforced Pavement systems; Sistemas de pavimentos reforzados con geosinteticos

    Energy Technology Data Exchange (ETDEWEB)

    Zornberg, J. G.

    2014-02-01

    Geo synthetics have been used as reinforcement inclusions to improve pavement performance. while there are clear field evidence of the benefit of using geo synthetic reinforcements, the specific conditions or mechanisms that govern the reinforcement of pavements are, at best, unclear and have remained largely unmeasured. Significant research has been recently conducted with the objectives of: (i) determining the relevant properties of geo synthetics that contribute to the enhanced performance of pavement systems, (ii) developing appropriate analytical, laboratory and field methods capable of quantifying the pavement performance, and (iii) enabling the prediction of pavement performance as a function of the properties of the various types of geo synthetics. (Author)

  6. Evaluation of Common Maintenance Methods for Flexible Pavements

    Directory of Open Access Journals (Sweden)

    Asma T. Ibraheem

    2011-01-01

    Full Text Available Problem statement: With the increasing use and awareness of pavement management systems and the growing emphasis on asset management of pavement infrastructure, it is important to strengthen the maintenance components of these systems and particularly the preventive maintenance component. Iraqi Roads don’t receive an effective and proper maintenance during their service life until they reach the state of major failure that requires rehabilitation. Roads in Iraq are being lost. Approach: In this study, a study of the status of maintenance methods for road pavements in Iraq with special reference to flexible pavements is presented. For this purpose, open and closed questionnaires were executed in Baghdad to investigate the status of road pavement maintenance in Iraq. Road maintenance offices as (Ministry of construction and Housing, State Corporation for Roads and Bridges, Amanat Baghdad, Project office, were included in the questionnaire to arrive at the level of maintenance and techniques followed to maintain paved road in Iraq. Results: The interviews carried out reveal that maintenance in Iraq has secondary importance, apparently with no special budget allocated for such important works. In addition the maintenance methods and techniques followed do not comply the developments and modern techniques. Conclusion/Recommendations: Poor and miss-management of maintenance works and activities leading to delays and accumulation of failure in the highway network that require unusual expenditures to repair and maintain the accumulated damages. Also shortages in resources allocated for maintenance works and this leads to the diversion of significant portion of the allocated fund for maintenance works toward purchasing of new, or additional equipment to be used for the construction of new roads. It is strongly recommended to design a planning system for management pavement maintenance of road network in Iraq and develop a particular failure criterion

  7. Integrating Place-based and Cultural Knowledge Systems into a Communicating Ocean Sciences course in Hawaii

    Science.gov (United States)

    Lemus, J.; Coopersmith, A.; Duncan Seraphin, K.

    2011-12-01

    The Pacific Ocean Literacy for Youth, Publics, Professionals and Scientists (POLYPPS) collaborative program between the University of Hawaii and the Center for Ocean Sciences Education Excellence - California (COSEE CA) at UC Berkeley operates on the premise that ocean literacy is most effectively achieved through scientists and educators working together within a place-based context. We have partnered with a dynamic and respected group of traditional practitioners and a graduate student trained in Hawaiian Studies to advise efforts for respectfully and responsibly integrating aspects of traditional ecological knowledge with the existing course material. The goal is to build a collaborative network that connects ocean research and teaching with traditional knowledge to facilitate active engagement in stewardship and policy by all ocean users. This presentation will include details of ways in which we have adapted the COSEE-CA courses in Communicating Ocean Sciences (COS) and Communicating Ocean Sciences for Informal Audiences (COSIA) for our island setting; approaches for contextualizing course elements that utilize local and traditional exemplars and knowledge systems; and example outreach projects produced by students in our Communicating Ocean Sciences courses.

  8. CERN’s Challenge-Based Innovation course welcomes new students

    CERN Multimedia

    Kate Kahle

    2014-01-01

    What do you get when you mix students from around the world with detector technologies developed at CERN and ask them to solve societal problems? Welcome to the Challenge-Based Innovation course.   The CBI students at IdeaSquare – a CERN building currently being renovated, which will be inaugurated in December. Students at CERN are no surprise; the Laboratory welcomes hundreds each year. But these 45 students, travelling from Spain, Finland, Norway, Italy and even Australia, are studying design, engineering, business and more. With their mix of backgrounds, they have come to CERN this week to view detector technologies in a very different way. They are here to follow the Challenge-Based Innovation (CBI) course, a Masters-level student programme developed by CERN in collaboration with a number of universities worldwide. They will be grouped into six teams and shown a range of detector technologies in collaboration with coaches and inspiration partners. In just six months, they will...

  9. Rationale for the Design of a Web-based Programming Course for Adults

    DEFF Research Database (Denmark)

    Bennedsen, Jens; Caspersen, Michael Edelgaard

    2003-01-01

    Web-based distance education is becoming more and more popular in particular for part-time educations primarily because it flexibly adapts to a busy life where family and work has first priority. Students can follow the course without wasting precious time traveling to and from campus several...... evenings a week, and participation can take place also in situations where it would otherwise be impossible (e.g. a sick child or a business trip). However, these advantages don't come for free: the students lose the social relations following from face-to-face contact with the lecturer and teaching...... assistant as well as the other students. Another serious drawback is the reduced bandwidth in communication among the different actors. Precautions have to be taken in order to compensate for these and other drawbacks. We describe a web-based introductory programming course for adults and the rationale...

  10. Implementation of Problem Based Learning (PBL) - in a Malaysian Teacher Education Course

    DEFF Research Database (Denmark)

    Borhan, Mohamad Termizi Bin; Yassin, Sopia Md

    2013-01-01

    The paper describes an employment of a Problem Based Learning (PBL) approach in a Malaysian graduate teacher education course. The discussions focus on how PBL was introduced, the PBL tasks and explore issues and benefits perceived by students. Data were obtained from journal reflections, intervi......The paper describes an employment of a Problem Based Learning (PBL) approach in a Malaysian graduate teacher education course. The discussions focus on how PBL was introduced, the PBL tasks and explore issues and benefits perceived by students. Data were obtained from journal reflections...... of participating in PBL class. The study also reiterated the important to align different curriculum elements and to address contextual elements in designs in effort to achieve designs that sensitive to local elements....

  11. A Pilot Study of Problem Formulation and Resolution in an Online Problem-based Learning Course

    Directory of Open Access Journals (Sweden)

    Rick Kenny

    2006-12-01

    Full Text Available This paper discusses an exploratory study to investigate the existence, and nature, of student problem formulation and resolution processes in an undergraduate online Problem-Based Learning (PBL course in Agricultural Sciences. We report on the use of a content analysis instrument developed to measure problem formulation and resolution (PFR processes in online asynchronous discussions (Murphy, 2004a, 2004b to analyze students' text-based, online discussions. The results offer evidence that students do engage in problem formulation and resolution and that these processes appear to be consistent with the PBL process carried out in this course. However, the nature of the PBL pedagogy, at least in this instructional context, ties the PBL problems to be solved tightly to a marked assignment structure and, therefore, appears to restrict the PFR process in its early and late stages.

  12. Social network analysis of a project-based introductory physics course

    Science.gov (United States)

    Oakley, Christopher

    2016-03-01

    Research suggests that students benefit from peer interaction and active engagement in the classroom. The quality, nature, effect of these interactions is currently being explored by Physics Education Researchers. Spelman College offers an introductory physics sequence that addresses content and research skills by engaging students in open-ended research projects, a form of Project-Based Learning. Students have been surveyed at regular intervals during the second semester of trigonometry-based course to determine the frequency of interactions in and out of class. These interactions can be with current or past students, tutors, and instructors. This line of inquiry focuses on metrics of Social Network analysis, such as centrality of participants as well as segmentation of groups. Further research will refine and highlight deeper questions regarding student performance in this pedagogy and course sequence.

  13. Study on the control course of ANFIS based aircraft auto-landing

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The control model in the course of an aircraft auto-landing is first proposed. Then, the common basic hypotheses in the design of a fuzzy logic controller are described. The fuzzy inference system of an aircraft auto-landing fuzzy controller in the course of automatic control on landing is investigated. The auto-landing model for controlling, membership functions of state variables, inference rules in the system, algorithms for fuzzy inference and defuzzification, etc, are analyzed and devised in detail with the emphasis on optimal analysis and design of Takagi-Sugeno ALFC based on adaptive neural fuzzy inference systems. Finally, the simulation for verification and analysis of the designed schemes is made by utilizing Simulink and fuzzy logic toolbox with MATLAB. The simulated results show that the ANFIS based T-S type ALFC scheme has excellent behavior in performance.

  14. Cold Region Pavements%寒区路面

    Institute of Scientific and Technical Information of China (English)

    GuyDore

    2002-01-01

    The article mainly discusses several essential problems of cold region pavement, including thermal cracking of asphalt concrete, cracking deterioration and heaving, frost heave, seasonal and long term roughness induced by different frost heave, frost heave cracking, bearing capacity loss during spring thaw. The reason for these problems is that cold region pavements are subjected to intense solicitation by climatic and environmental factors. The author offers several models corresponding to the solicitation. Furthermore in conclusion of the article the author indicates future research for cold region.

  15. Evaluation of multilayered pavement structures from measurements of surface waves

    Science.gov (United States)

    Ryden, N.; Lowe, M.J.S.; Cawley, P.; Park, C.B.

    2006-01-01

    A method is presented for evaluating the thickness and stiffness of multilayered pavement structures from guided waves measured at the surface. Data is collected with a light hammer as the source and an accelerometer as receiver, generating a synthetic receiver array. The top layer properties are evaluated with a Lamb wave analysis. Multiple layers are evaluated by matching a theoretical phase velocity spectrum to the measured spectrum. So far the method has been applied to the testing of pavements, but it may also be applicable in other fields such as ultrasonic testing of coated materials. ?? 2006 American Institute of Physics.

  16. Thin, applied surfacing for improving skid resistance of concrete pavements

    Science.gov (United States)

    Scholer, C. F.

    1980-12-01

    The use of select aggregate in a thin wearing surface of portland cement mortar to prolone or restore a concrete pavement's ability to develop high friction was accomplished. Two fine aggregates, blast furnace slag and lightweight expanded shale were found to exhibit skid resistance greater than the other aggregates evaluated. The British polishing wheel was used in the laboratory evaluation of aggregate to simulate wear. The need for a method of restoring friction to a worn, but otherwise sound concrete pavement led to a field evaluation of several different techniques for placing a very thin overlay. The successful method was a broomed, very thin layer of mortar, 3 mm thick.

  17. A modified approach to team-based learning in linear algebra courses

    Science.gov (United States)

    Nanes, Kalman M.

    2014-11-01

    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 controlled analysis of the effects of TBL on the student learning experience in the first year of TBL use.

  18. Functionality Enhancement of Industrialized Optical Fiber Sensors and System Developed for Full-Scale Pavement Monitoring

    Directory of Open Access Journals (Sweden)

    Huaping Wang

    2014-05-01

    Full Text Available Pavements always play a predominant role in transportation. Health monitoring of pavements is becoming more and more significant, as frequently suffering from cracks, rutting, and slippage renders them prematurely out of service. Effective and reliable sensing elements are thus in high demand to make prognosis on the mechanical properties and occurrence of damage to pavements. Therefore, in this paper, various types of functionality enhancement of industrialized optical fiber sensors for pavement monitoring are developed, with the corresponding operational principles clarified in theory and the performance double checked by basic experiments. Furthermore, a self-healing optical fiber sensing network system is adopted to accomplish full-scale monitoring of pavements. The application of optical fiber sensors assembly and self-healing network system in pavement has been carried out to validate the feasibility. It has been proved that the research in this article provides a valuable method and meaningful guidance for the integrity monitoring of civil structures, especially pavements.

  19. How a Web-Based Course Facilitates Acquisition of English for Academic Purposes

    Directory of Open Access Journals (Sweden)

    Jin Chen

    2004-05-01

    Full Text Available This paper describes an experimental study aimed at investigating the learning effectiveness of a Web-based course called Academic English (EAP for Japanese learners of English. The main focus of the study was to examine the form, function, and impact of interaction in the course. Twenty university-level EFL students participated in this experiment. They were randomly assigned to two treatment groups: a controlled group with inter-personal task treatment and an experiment group with intra-personal task treatment. Regarding effectiveness of the interactivity dimension in language acquisition, there was one independent variable, type of treatments, and two dependent variables, achievement and attitude measurements. The achievement variable was used to address the extent of learning due to the two treatment conditions. The attitude variable was used to address the degree of motivation towards a Web-based communication platform as well as the enforced interaction functions. Statistical analyses revealed no significant effect of treatment on either comprehension or general L2 development, but significant differences were found with respect to language interaction for task completion under different task treatments. Therefore, it was concluded that this Web-based course was well designed to maximize the students' language learning experience as well as to improve their language abilities in English. Further research is needed to examine the notion of self-repair in students' production in the target language.

  20. Passive pavement-mounted acoustical linguistic drive alert system and method

    Science.gov (United States)

    Kisner, Roger A.; Anderson, Richard L.; Carnal, Charles L.; Hylton, James O.; Stevens, Samuel S.

    2001-01-01

    Systems and methods are described for passive pavement-mounted acoustical alert of the occupants of a vehicle. A method of notifying a vehicle occupant includes providing a driving medium upon which a vehicle is to be driven; and texturing a portion of the driving medium such that the textured portion interacts with the vehicle to produce audible signals, the textured portion pattern such that a linguistic message is encoded into the audible signals. The systems and methods provide advantages because information can be conveyed to the occupants of the vehicle based on the location of the vehicle relative to the textured surface.