WorldWideScience
1

Pavement distress detection and severity analysis  

Science.gov (United States)

Automatic recognition of road distresses has been an important research area since it reduces economic loses before cracks and potholes become too severe. Existing systems for automated pavement defect detection commonly require special devices such as lights, lasers, etc, which dramatically increase the cost and limit the system to certain applications. Therefore, in this paper, a low cost automatic pavement distress evaluation approach is proposed. This method can provide real-time pavement distress detection as well as evaluation results based on the color images captured from a camera installed on a survey vehicle. The entire process consists of two main parts: pavement surface extraction followed by pavement distress detection and classification. In the first part, a novel color segmentation method based on a feed forward neural network is applied to separate the road surface from the background. In the second part, a thresholding technique based on probabilistic relaxation is utilized to separate distresses from the road surface. Then, by inputting the geometrical parameters obtained from the detected distresses into a neural network based pavement distress classifier, the defects can be classified into different types. Simulation results are given to show that the proposed method is both effective and reliable on a variety of pavement images.

Salari, E.; Bao, G.

2011-03-01

2

A Novel Pavement Distress Image Filtering Algorithm  

Directory of Open Access Journals (Sweden)

Full Text Available Combined the Nonsubsampled Contourlet Transform (NSCT with compressed sensing de-noising theory, this study proposed a compressed sensing image filtering algorithm in the NSCT transform domain. This algorithm adopted the transform domain filtering method. Firstly, the NSCT was used to do multi-scale and multi-directional transform on the input noisy pavement distress Image which was mapped to the transform domain. Then the compressed sensing theory was used to filter the high-frequency sub-band coefficients. The experiment results show that this algorithm improves the effectiveness and timeliness of the pavement distress image filtering.

Feng Xin

2013-01-01

3

A Novel Pavement Distress Image Filtering Algorithm  

OpenAIRE

Combined the Nonsubsampled Contourlet Transform (NSCT) with compressed sensing de-noising theory, this study proposed a compressed sensing image filtering algorithm in the NSCT transform domain. This algorithm adopted the transform domain filtering method. Firstly, the NSCT was used to do multi-scale and multi-directional transform on the input noisy pavement distress Image which was mapped to the transform domain. Then the compressed sensing theory was used to filter the high-frequency...

Feng Xin; Dang Jian-Wu; Shen Yu; Wang Yang-Ping

2013-01-01

4

Evaluation of Multilayered Pavement Structures from Measurements of Surface Waves  

Science.gov (United States)

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.

Ryden, Nils; Lowe, Michael J. S.; Cawley, Peter; Park, Choon B.

2006-03-01

5

Evaluation of multilayered pavement structures from measurements of surface waves  

Science.gov (United States)

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.

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

2006-01-01

6

Flexible pavement performance evaluation using deflection criteria  

Science.gov (United States)

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

Wedner, R. J.

1980-04-01

7

Propagation Mechanisms for Surface Initiated Crackingin Composite Pavements  

Directory of Open Access Journals (Sweden)

Full Text Available The primary objective of this study was to identify the mechanisms for the development and propagation of longitudinal cracks that initiate at the surface of composite pavement. In this study the finite element program ANSYS version (5.4 was used and the model worked out using this program has the ability to analyze a composite pavement structure of different layer properties. Also, the aim of this study was modeling and analyzing of the composite pavement structure with the physical presence of crack induced in concrete underlying layer. The results obtained indicates that increasing the thickness of the asphalt layer tends to decrease the stress intensity factor, which may be attributed to the rapidly decrease of horizontal tensile stress in the asphalt layer. The cracks initiate at the surface due to high vertical stress and shear stress from wheel loads tends to propagate downward due tensile stress generated at the bottom of the asphalt layer or near crack tip, and the whole process occur at the same location of the existing cracks in underlying concrete layer rather than travel up from existing crack. As the load position varies from the crack zone, this result in tensile stresses or tension at the crack tip, leading to increase the stress intensity factor and intern result in crack propagation further into the depth of the pavement.

Duraid Ali Al Khafagy

2009-01-01

8

A study of the effects of adding ice retardant additives to pavement surface course materials  

OpenAIRE

The formation of ice and snow on pavement surfaces is a recurring problem, creating hazardous driving conditions, restricting public mobility as well as having adverse economic effects. Current winter operations primarily consist of the correctly timed application of de-icing chemicals to the pavement surface to prevent hazardous conditions occurring. It would be desirable to develop new and improved ways of modifying the pavement surface, to prevent or at least delay the buildup of ice a...

Wright, Michael

2013-01-01

9

Effect of pavement temperature on the macrotexture of a semidense asphalt surface  

OpenAIRE

The temperature of the softening point of most bitumen is above 35ºC. Increasing the pavement temperature could change the texture surface of the pavement. The aim of this work is to analyze the influence of the surface temperature on the macrotexture of a semidense asphalt pavement located in an urban area and a semidense asphalt sample in laboratory. The superficial macrotexture profiles at different surface temperatures were measured with the LaserStaticPG-LA2IC and a texture scanner. The...

Luong, J.; Bueno, M.; Va?zquez, V. F.; Vin?uela, U.; Paje, S. E.

2012-01-01

10

Laser Scanning on Road Pavements: A New Approach for Characterizing Surface Texture  

OpenAIRE

The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the “texture” appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an expe...

Gabriele Bitelli; Andrea Simone; Fabrizio Girardi; Claudio Lantieri

2012-01-01

11

Fusing complementary images for pavement cracking measurements  

Science.gov (United States)

Cracking is a major pavement distress that jeopardizes road serviceability and traffic safety. Automated pavement distress survey (APDS) systems have been developed using digital imaging technology to replace human surveys for more timely and accurate inspections. Most APDS systems require special lighting devices to illuminate pavements and prevent shadows of roadside objects that distort cracks in the image. Most artificial lighting devices are laser based, and are either hazardous to unprotected people or require dedicated power supplies on the vehicle. This study was aimed to develop a new imaging system that can scan pavement surface at highway speed and determine the level of severity of pavement cracking without using any artificial lighting. The new system consists of dual line-scan cameras that are installed side by side to scan the same pavement area as the vehicle moves. Cameras are controlled with different exposure settings so that both sunlit and shadowed areas can be visible in two separate images. The paired images contain complementary details useful for reconstructing an image in which the shadows are eliminated. This paper intends to present (1) the design of the dual line-scan camera system, (2) a new calibration method for line-scan cameras to rectify and register paired images, (3) a customized image-fusion algorithm that merges the multi-exposure images into one shadow-free image for crack detection, and (4) the results of the field tests on a selected road over a long period.

Yao, Ming; Zhao, Zuyun; Yao, Xun; Xu, Bugao

2015-02-01

12

Evaluation of 407ETR Pavement  

Energy Technology Data Exchange (ETDEWEB)

A pavement evaluation study was conducted on the 407 express toll route (ETR) multi-lane, electronic toll highway that runs 69 km across the north end of Toronto. The objective was to determine the pavement condition and to identify areas with a high probability of premature deterioration. While the highway currently consists of four lanes in most areas except one where it expands to 6 lanes, it has the capability to expand to 10 lanes to accommodate future traffic needs. The highway, which has been in service since 1997, was constructed in stages and took 4.5 years to complete. During the evaluation study, advanced, non-destructive testing techniques were used to detect performance problems before they escalate. The evaluation also consisted of a visual distress survey, a profile based rideability (roughness) survey, a skid resistance survey and a limited deflection survey using the Falling Weight Deflectometer. The following analyses were also performed: (1) calculation of the MTO Distress Manifestation Index, (2) the International Roughness Index, (3) the MTO Riding Comfort Index, and (4) the Surface Friction Number. Other tests included estimating joint faulting and determining the structural capacity of the pavement. Load transfer efficiency across transverse joints was also evaluated and the existence of voids underneath the PCC slabs were also detected. The evaluation indicated that the condition of the pavement is good but some preventive maintenance is needed. 1 ref., 4 tabs., 12 figs.

Zaghloul, S. [Stantec Consulting Ltd., Cambridge, ON (Canada)

2001-07-01

13

Pavement nondestructive evaluation using finite-element dynamic simulation  

Science.gov (United States)

This paper describes the nondestructive evaluation devices, visual distress survey and coring used to investigate jointed concrete pavement performance in northern Mississippi. 3D finite-element models were developed to simulate in-service conditions and to characterize in-situ material properties. Reasonable good agreement is found between in-situ moduli backcalculated from the dynamic analysis of falling weight deflectometer (FWD) deflections measured on selected pavements and laboratory moduli. Effects of load pulse shape, cracking, and discontinuities on the surface deflection response of pavements subjected to FWD load wee also investigated. It is shown that 3D analysis of temperature distribution and resulting thermal stresses play a significant role int he performance of concrete pavements. The study results demonstrated the extensive usefulness of the finite-element dynamic analysis and limitations of the static multilayered analysis and other pavement analysis programs which do not allow for crack modeling and dynamic analysis.

Uddin, W.; Hackett, R. M.

1996-11-01

14

Pavement cracking measurements using 3D laser-scan images  

International Nuclear Information System (INIS)

Pavement condition surveying is vital for pavement maintenance programs that ensure ride quality and traffic safety. This paper first introduces an automated pavement inspection system which uses a three-dimensional (3D) camera and a structured laser light to acquire dense transverse profiles of a pavement lane surface when it carries a moving vehicle. After the calibration, the 3D system can yield a depth resolution of 0.5 mm and a transverse resolution of 1.56 mm pixel?1 at 1.4 m camera height from the ground. The scanning rate of the camera can be set to its maximum at 5000 lines s?1, allowing the density of scanned profiles to vary with the vehicle's speed. The paper then illustrates the algorithms that utilize 3D information to detect pavement distress, such as transverse, longitudinal and alligator cracking, and presents the field tests on the system's repeatability when scanning a sample pavement in multiple runs at the same vehicle speed, at different vehicle speeds and under different weather conditions. The results show that this dedicated 3D system can capture accurate pavement images that detail surface distress, and obtain consistent crack measurements in repeated tests and under different driving and lighting conditions. (paper)

15

Methods to Use Surface Infiltration Tests in Permeable Pavement Systems to Determine Maintenance Frequency  

Science.gov (United States)

Currently, there is limited guidance on selecting test sites to measure surface infiltration rates in permeable pavement systems to determine maintenance frequency. The ASTM method (ASTM C1701) for measuring infiltration rate of in-place pervious concrete suggest to either (1) p...

16

Analysis of Load Stress for Asphalt Pavement of Lean Concrete Base  

Science.gov (United States)

The study revealed that whether it is early distresses in asphalt pavement or not depends largely on working performance of base. In the field of asphalt pavement, it is widely accepted that lean concrete base, compared with the general semi-rigid base, has better working performance, such as high strength and good eroding resistance. Problem of early distresses in asphalt pavement, which caused by more traffic loadings, can be settled effectively when lean concrete is used in asphalt pavement. Traffic loading is important parameter used in the analysis of the new pavement design. However, few studies have done extensive and intensive research on the load stress for asphalt pavement of lean concrete base. Because of that, it is necessary to study the load stress for the asphalt pavement. In the paper, first of all, three-dimension finite element model of the asphalt pavement is created for the aim of doing mechanical analysis for the asphalt pavement. And then, the two main objectives of this study are investigated. One is analysis for load stress of lean concrete base, and the other is analysis for load stress of asphalt surface. The results show that load stress of lean concrete base decreases, decrease and increase with increase of base's thickness, surface's thickness and ratio of base's modulus to foundation's modulus respectively. So far as the asphalt surface is concerned, maximum shearing stress, which is caused by load, is evident in asphalt surface which is located in transverse contraction joint of lean concrete base of asphalt pavement. Maximum shearing stress decrease, decrease, decrease and increase respectively with increase of the surface's modulus, the surface's thickness, base's thickness and ratio of base's modulus to foundation's modulus.

Lijun, Suo; Xinwu, Wang

17

EFFECTS OF PAVEMENT SURFACE TEMPERATURE ON THE MODIFICATION OF URBAN THERMAL ENVIRONMENT  

OpenAIRE

Urban centres continue to experience escalating average summer temperature over the last fifty years. Temperature in the urban core cites have been rising due to rapid growth of urbanization in the latter half of the twentieth century (Akbari et al., 1989). Outdoor experiments were conducted to investigate the effects of different movement of materials on the urban thermal environment. Meteorological conditions such as air temperature, pavement surface temperature, Relative humidity and wind ...

Sarat, Adebayo-aminu; Eusuf, Muhammad Abu

2012-01-01

18

Laser Scanning on Road Pavements: A New Approach for Characterizing Surface Texture  

Directory of Open Access Journals (Sweden)

Full Text Available The surface layer of road pavement has a particular importance in relation to the satisfaction of the primary demands of locomotion, such as security and eco-compatibility. Among those pavement surface characteristics, the “texture” appears to be one of the most interesting with regard to the attainment of skid resistance. Specifications and regulations, providing a wide range of functional indicators, act as guidelines to satisfy the performance requirements. This paper describes an experiment on the use of laser scanner techniques on various types of asphalt for texture characterization. The use of high precision laser scanners, such as the triangulation types, is proposed to expand the analysis of road pavement from the commonly and currently used two-dimensional method to a three-dimensional one, with the aim of extending the range of the most important parameters for these kinds of applications. Laser scanners can be used in an innovative way to obtain information on areal surface layer through a single measurement, with data homogeneity and representativeness. The described experience highlights how the laser scanner is used for both laboratory experiments and tests in situ, with a particular attention paid to factors that could potentially affect the survey.

Gabriele Bitelli

2012-07-01

19

DRAINAGE AND FLEXIBLE PAVEMENT PERFORMANCE  

Directory of Open Access Journals (Sweden)

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.

SIDDHARTHA ROKADE

2012-04-01

20

EFFECTS OF PAVEMENT SURFACE TEMPERATURE ON THE MODIFICATION OF URBAN THERMAL ENVIRONMENT  

Directory of Open Access Journals (Sweden)

Full Text Available Urban centres continue to experience escalating average summer temperature over the last fifty years. Temperature in the urban core cites have been rising due to rapid growth of urbanization in the latter half of the twentieth century (Akbari et al., 1989. Outdoor experiments were conducted to investigate the effects of different movement of materials on the urban thermal environment. Meteorological conditions such as air temperature, pavement surface temperature, Relative humidity and wind velocity were recorded to determine temperature differences among Asphalt/concrete, interlocking bricks and grass surfaces.

SARAT, Adebayo-Aminu

2012-01-01

21

Shakedown analysis and design of flexible road pavements under moving surface loads  

OpenAIRE

Flexible road pavements often fail due to excessive rutting. as a result of cumulative vertical permanent deformation under repeated traffic loads. The currently used analytical approach to flexible pavement design evaluates the pavement life in terms of critical elastic strain at the top of the subgrade. Hence, the plastic pavement behaviour is not properly considered. Shakedown analysis can take into account the material plasticity and guarantee structure stability under repeated loads. It ...

Wang, Juan

2011-01-01

22

Evaluation of Surface Infiltration Testing Procedures in Permeable Pavement Systems  

Science.gov (United States)

The ASTM method (ASTM C1701) for measuring infiltration rate of in-place pervious concrete provides limited guidance on how to select testing locations, so research is needed to evaluate how testing sites should be selected and how results should be interpreted to assess surface ...

23

Visual surveying platform for the automated detection of road surface distresses  

Science.gov (United States)

Road distresses, such as potholes and edge cracks, are not only a source of frustration to drivers but also negatively impact the economy due to damage to motor vehicles and costly ro6ad repairs. Regular and rapid pavement inspection and maintenance is vital to preventing pothole formation and growth. To improve the efficiency of maintenance and reduce the cost thereof, the Visual Surveying Platform (VSP) is being developed that will automatically detect and analyse road distresses. The VSP consists of a vehicle mounted sensor system, consisting of a high speed camera and a Global Positioning System (GPS) receiver, and an analysis and visualization software suite. The system extracts both a visual image and the coordinates of a detected road defect from recorded video and presents it in an interactive interface for use by technical experts and maintenance schedulers. The VSP automatically detects and classifies road distresses using a two-stage artificial neural network framework. Video frames first undergo hue, saturation and value (HSV) colour space conversion as well as a spatial frequency transformation before being used as inputs to the neural networks. A road detector neural network first classifies which section of the image contains the road, after which a distress detector neural network identifies those road regions containing defects. Although the VSP can be adapted to detect any type of road distress it has been trained to specifically detect potholes. An initial prototype of the VSP was designed and constructed. The prototype was also trained and tested on real-world data collected from provincial roads.

Naidoo, Thegaran; Joubert, Deon; Chiwewe, Tapiwa; Tyatyantsi, Ayanda; Rancati, Bruno; Mbizeni, Asanda

2014-06-01

24

Fast simulated annealing inversion of surface waves on pavement using phase-velocity spectra  

Science.gov (United States)

The conventional inversion of surface waves depends on modal identification of measured dispersion curves, which can be ambiguous. It is possible to avoid mode-number identification and extraction by inverting the complete phase-velocity spectrum obtained from a multichannel record. We use the fast simulated annealing (FSA) global search algorithm to minimize the difference between the measured phase-velocity spectrum and that calculated from a theoretical layer model, including the field setup geometry. Results show that this algorithm can help one avoid getting trapped in local minima while searching for the best-matching layer model. The entire procedure is demonstrated on synthetic and field data for asphalt pavement. The viscoelastic properties of the top asphalt layer are taken into account, and the inverted asphalt stiffness as a function of frequency compares well with laboratory tests on core samples. The thickness and shear-wave velocity of the deeper embedded layers are resolved within 10% deviation from those values measured separately during pavement construction. The proposed method may be equally applicable to normal soil site investigation and in the field of ultrasonic testing of materials. ?? 2006 Society of Exploration Geophysicists.

Ryden, N.; Park, C.B.

2006-01-01

25

Precast concrete pavements  

Science.gov (United States)

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

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

1981-11-01

26

Automated management for pavement inspection system (AMPIS)  

Science.gov (United States)

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.

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

2003-08-01

27

Weak interlayers in flexible and semi-flexible road pavements: Part 1  

Scientific Electronic Library Online (English)

Full Text Available Weak layers, interlayers, laminations and/or interfaces in the upper structural layers of road pavements are specifically prohibited in most road-building specifications. However, such layers are extremely common and often lead to premature pavement distress. In Part 1 of this two-part set of papers [...] , it is shown that from experience with heavy vehicle simulator (HVS) and dynamic cone penetrometer (DCP) testing, the presence of such layers and/or conditions at any depth in the structural layers of a flexible or semi-flexible pavement is far more deleterious than is commonly appreciated. In Part 2 the effects of these weak layers are further modelled and discussed using various examples based an HVS testing and mechanistic pavement analyses. In particular, a weak upper base course of a cemented pavement under a thin bituminous surfacing may lead to severe surfacing (and upper base) failure within a matter of weeks to months after opening to traffic, not excluding failure even during construction. In this paper (Part 1), the causes of weak layers, interlayers, laminations and/or interfaces, together with simple methods for their detection during construction and analyses of their effects on the structural capacity of flexible and semi-rigid (cemented) road pavements, are briefly discussed.

F, Netterberg; M, de Beer.

2012-04-01

28

Weak interlayers in flexible and semi-flexible road pavements: Part 1  

Directory of Open Access Journals (Sweden)

Full Text Available Weak layers, interlayers, laminations and/or interfaces in the upper structural layers of road pavements are specifically prohibited in most road-building specifications. However, such layers are extremely common and often lead to premature pavement distress. In Part 1 of this two-part set of papers, it is shown that from experience with heavy vehicle simulator (HVS and dynamic cone penetrometer (DCP testing, the presence of such layers and/or conditions at any depth in the structural layers of a flexible or semi-flexible pavement is far more deleterious than is commonly appreciated. In Part 2 the effects of these weak layers are further modelled and discussed using various examples based an HVS testing and mechanistic pavement analyses. In particular, a weak upper base course of a cemented pavement under a thin bituminous surfacing may lead to severe surfacing (and upper base failure within a matter of weeks to months after opening to traffic, not excluding failure even during construction. In this paper (Part 1, the causes of weak layers, interlayers, laminations and/or interfaces, together with simple methods for their detection during construction and analyses of their effects on the structural capacity of flexible and semi-rigid (cemented road pavements, are briefly discussed.

F Netterberg

2012-04-01

29

Experimental Evaluation of Anti-Stripping Additives Mixing in Road Surface Pavement Materials  

Directory of Open Access Journals (Sweden)

Full Text Available Most road surfaces in Taiwan are paved with asphalt concrete but the phenomena of rutting, cracking and stripping of the pavement are frequently occurring due to the effects of traffic flow, thermal variation and water erosion caused by rain. In this study, a series of experiments were performed to examine the effectiveness of anti-stripping fillers, which include; rock flour, rock flour with 1% lime and rock flour with 1% cement, respectively, in the mixture of asphalt concrete. The experimental mixing results showed that the case of rock flour with 1% lime has a relatively better performance in several categories including stability value, flow value, retained strength, wrapped asphalt rate in grains, resilient modulus, dynamic stability and rate of rutting deformation. The evaluated information implies that this filler can increase the asphalt concrete’s abilities to resist rutting deformation and stripping of the road surface, thus increasing the durability. The results also provide a good reference for using in road construction with similar regional characteristics to Taiwan.

Tienfuan Kerh

2005-01-01

30

Effects of using silica fume and polycarboxylate-type superplasticizer on physical properties of cementitious grout mixtures for semiflexible pavement surfacing.  

Science.gov (United States)

Semi-flexible pavement surfacing is a composite pavement that utilizes the porous pavement structure of the flexible bituminous pavement, which is subsequently grouted with appropriate cementitious materials. This study aims to investigate the compressive strength, flexural strength, and workability performance of cementitious grout. The grout mixtures are designed to achieve high strength and maintain flow properties in order to allow the cement slurries to infiltrate easily through unfilled compacted skeletons. A paired-sample t-test was carried out to find out whether water/cement ratio, SP percentages, and use of silica fume influence the cementitious grout performance. The findings showed that the replacement of 5% silica fume with an adequate amount of superplasticizer and water/cement ratio was beneficial in improving the properties of the cementitious grout. PMID:24526911

Koting, Suhana; Karim, Mohamed Rehan; Mahmud, Hilmi; Mashaan, Nuha S; Ibrahim, Mohd Rasdan; Katman, Herdayati; Husain, Nadiah Md

2014-01-01

31

Evaluation of a new construction pavement section using the mechanistic-empirical pavement design guide  

Science.gov (United States)

The AASHTO Mechanistic-Empirical Design Guide (MEPDG) is one of several "next generation" pavement design approaches intended to address limitations of older empirical methods. This research investigated the capabilities and performance of the MEPDG through analyses of an empirically-designed section of NH Route 16, which the New Hampshire Department of Transportation (NHDOT) indicated may be under-designed. MEPDG distress predictions indicate that the pavement section should achieve a service life of at least 10 years. This was supported by the fatigue analysis of the base course, which also indicated that the pavement may have been damaged by traffic loads prior to the completion of the surface course. During this research, a number of limitations and model behaviors of the MEPDG were observed, some with significant importance to this analysis and to future projects within New Hampshire. Because implementation and full realization of the MEPDG requires significant investment, the results of this research should be considered before undertaking steps towards adoption of the software.

Lowe, Justin

32

Water Quality Performance of Three Side-by-Side Permeable Pavement Surface Materials: Three Year Update  

Science.gov (United States)

Communities are increasingly installing structural low impact development (LID) practices to mange stormwater and reduce pollutant loads associated with stormwater runoff. Permeable pavement is a LID practice that has limited research on working-scale, side-by-side performance o...

33

Bridge and pavement maintenance  

Science.gov (United States)

Deterioration of New York State Highway structures; precast repair of continuously reinforced concrete pavement (abridgment) patching of continuously reinforced concrete pavements, evaluation of several maintenance methods for continuously reinforced concrete pavement, patching jointed concrete pavements, highway pavement repairs by using polymer concrete, pressure grouting of concrete pavements, and choosing cost-effective maintenance are discussed.

Fitzpatrick, M. W.; Law, D. A.; Dixon, W. C.; Elkins, G. E.; Mucullough, B. F.; Darter, M. I.; Yoder, E. J.; Florence, R. H., Jr.; Virkler, S. J.; McGhee, K. H.

1981-03-01

34

Mechanistic interpretation of nondestructive pavement testing deflections  

Science.gov (United States)

A method for the back calculation of material properties in flexible pavements based on the interpretation of surface deflection measurements is proposed. The ILLI-PAVE, a stress-dependent finite element pavement model, was used to generate data for developing algorithms and nomographs for deflection basin interpretation. Twenty four different flexible pavement sections throughout the State of Illinois were studied. Deflections were measured and loading mode effects on pavement response were investigated. The factors controlling the pavement response to different loading modes are identified and explained. Correlations between different devices are developed. The back calculated parameters derived from the proposed evaluation procedure can be used as inputs for asphalt concrete overlay design.

Hoffman, M. S.; Thompson, M. R.

1981-06-01

35

Determination of the heating temperature of potholes surface on road pavement in the process of repairs using hot asphalt concrete mixes  

Directory of Open Access Journals (Sweden)

Full Text Available In the process of roads construction the necessary transport and operational characteristics should be achieved, which depend on the quality of the applied, material and technologies. Under the loads of transport means and the influence of weather conditions on the road pavement deformations and destructions occur, which lead to worsening of transport and operational characteristics, decrease of operational life of the road and they are often the reason of road accidents. According to the data of the Strategic Research Center of "Rosgosstrah" more than 20 % of road accidents in Russia occur due to bad quality of road pavement. One of the main directions in traffic security control and prolongation of operational life for road pavement of non-rigid type is road works, as a result of which defects of pavement are eliminated and in case of timely repairs of high quality the operational life of the road increases for several years. The most widely used material for non-rigid pavement repairs is hot road concrete mixes and in case of adherence to specifications they provide high quality of works. The authors investigate the problems of hot asphalt concrete mixes for repairs of road surfaces of non-rigid type. The results of the study hot asphalt concrete mix’s temperature regimes are offered in case of repair works considering the temperature delivered to the work site and the ambient temperature depending on the type of mix and class of bitumen.

Giyasov Botir Iminzhonovich

2014-12-01

36

Technical and Economic Sustainability of Concrete Pavements  

Directory of Open Access Journals (Sweden)

Full Text Available Economic evaluation of road pavements is as important as their technical and structural design: often only initial construction costs are calculated to assess economic project sustainability. Instead, forgetting maintenance costs exposes society to unacceptable risks of expensive and incorrect decisions. Road pavements design and construction solutions affect maintenance works during service life, which not only entail economical and financial expenditures, but also damage service regularity for users and affect environmental impact. The analysis of pavement distress and the study of its evolution during service life can contribute to find the financially most advantageous solution. This paper shows a software program developed to analyze structural, functional and financial performances of road concrete pavements both doweled slabs and continuously reinforced.

Laura Moretti

2014-04-01

37

An experience on street pavement maintenance program in small region- (Bafq city  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports an experience on Pavement Maintenance plan of the Research Team of the Islamic Azad University- Bafq Branch. The City of Bafq streets are failing at a growing rate, despite all the efforts of Pavement Management, improved efficiencies in street maintenance operations, contracted work and sharing equipment with other agencies. Pavements in this range show some form of distress or wear that requires more than a life extending achievement. In this group, a well-designed pavement will have served at least 75% of its life and the authority of the pavement has dropped by about 40%.

Khabiry Mehdi

2009-05-01

38

FUEL CONSUMPTION & ENERGY DISSIPATION THROUGH ROAD PAVEMENT CHARACTERISTIC  

OpenAIRE

This thesis estimates the effect of pavement characteristic on energy dissipation of a rolling vehicle tyre. On objective of this study is to compare the relative amount of energy dissipated in pavement by the rolling depending on the pavement materials surface condition & environmental condition also. The study also assesses the effect of the vertical deflection, induced by the tyre, on overall energy dissipation in pavement. A comprehensive literature was carried out to pr...

Dipanjan Mukherjee

2014-01-01

39

Analysis of pavement serviceability for the Aashto Design Method: The Chilean Case  

International Nuclear Information System (INIS)

Serviceability is an indicator that represents the level of service a pavement provides to the users. This subjective opinion is closely related to objective aspects, which can be measured on the pavement's surface. This research aims specifically at relating serviceability results obtained by a 9-member evaluation panel, representing general public as closely as possible to parameters (particularly of roughness) measured within instruments on 30, 25 and 11 road sections of asphalt concrete, Portland cement concrete and asphalt overlay respectively. Results show that prediction of serviceability is quite accurate based on roughness evaluation, while also revealing that, by comparison to studies in more developed countries, Chileans are seemingly more tolerant, in that they assign a somewhat high rating to ride quality. Furthermore, visible distress does not have a significant influence on serviceability values for Chilean users. A ratio between International Roughness Index (IRI) and Serviceability, as defined by AASHTO, was developed and may be used in this design method. Results for the final pavement condition of urban pavements were obtained (IRI-asphalt final=5.9, IRI-concrete final=8.1). (author)

40

Using ground-penetrating radar for assessing highway pavement thickness  

Science.gov (United States)

Surface distress is a fairly good indicator of rehabilitation needs but it does not directly relate to remaining life estimates. Mechanistic pavement design requires that strains be calculated utilizing more or less complex modeling. Over the years many devices measuring surface deflections under a given load have been developed. The device by choice for assessing strains due to load is the falling weight deflectometer (FWD). It creates an impulse load on the pavement surface. The data are commonly used in models for backcalculation of elastic moduli and strains. More complex modeling would involve finite element or dynamic element methods. The FWD method has proven to be an excellent tool for overlay design. For this purpose its simplicity and straightforwardness are well documented. However, to successfully backcalculate layer stiffness adequate layer thickness is needed. Thus there is a strong need for assessing layer data at testing points. Using Ground Penetrating Radar (GPR) it is possible to achieve data without coring. The present paper is a part of an ongoing bearing capacity study carried out by a regional road administration in central Sweden. Its objective is to optimize testing for equipment and methods used and presently available. In addition to evaluate the results from the study, the present paper discusses some other applications for GPR that may evolve from it.

Lenngren, Carl A.; Bergstrom, Joergen; Ersson, Benny M.

2000-07-01

41

Measurement of the Cooling Efficiency of Pavement-Watering as an Urban Heat Island Mitigation Technique  

Directory of Open Access Journals (Sweden)

Pavement watering was found to lower pavement surface temperatures by several degrees for several hours after watering, while also strongly reducing its cooling rate a few hours before and after sunset. Heat flux and storage at a depth of 5 cm in the pavement were also found to have been significantly reduced, especially during direct sunlight exposure, but also when the pavement was in the shade. Uninterrupted watering appears necessary during direct sunlight exposure of the pavement to maximize efficiency.

Martin Hendel

2015-03-01

42

An Investigation into the Mechanics of Windblown Dust Entrainment from Nickel Slag Surfaces Resembling Armoured Desert Pavements  

Science.gov (United States)

The purpose of this thesis is to investigate the dynamics of PM 10 emission from a nickel slag stockpile that closely resembles a desert pavement in physical characteristics. In the field, it was observed that slag surfaces develop by natural processes into a well-armoured surface over some period of time. The surface then consists of two distinct layers; a surficial armour layer containing only non-erodible gravel and cobble-sized clasts, and an underlying dust-laden layer, which contains a wide size range of slag particles, from clay-sized to cobble-sized. This surficial armour layer protects the underlying fines from wind entrainment, at least under typical wind conditions; however, particle emissions still do occur under high wind speeds. The dynamics of particle entrainment from within these surfaces are investigated herein. It is shown that the dynamics of the boundary layer flow over these lag surfaces are influenced by the inherent roughness and permeability of the surficial armour layer, such that the flow resembles those observed over and within vegetation canopies, and those associated with permeable gravel-bed river channels. Restriction of air flow within the permeable surface produces a high-pressure zone within the pore spaces, resulting in a Kelvin-Helmholtz shear instability, which triggers coherent motions in the form of repeating burst-sweep cycles. Using Laser Doppler Anemometry (LDA), it is demonstrated that the lower boundary layer is characterized by both Q4 sweeping motions and Q2 bursting motions, while the upper boundary layer is dominated by Q2 bursts. Pore air motions within the slag material were measured using buried pressure ports. It is shown that the mean pressure gradient which forms within the slag material results in net upward displacement of air, or wind pumping. However, this net upward motion is a result of rapid oscillatory motions which are directly driven by coherent boundary layer motions. It is also demonstrated that these coherent motions are able to penetrate at least 4 cm through the surficial armour layer, thereby transporting turbulent kinetic energy (TKE) downward to the dust-laden sub-surface layer. This represents a mechanism of momentum transfer that is able to reach the erodible material, while the wind pumping effect represents a mechanism for particle exhaustion.

Sanderson, Robert Steven

43

Monitoring the condition of roads pavement surfaces: proposal of methodology using hyperspectral images / Monitoramento das condições das superfícies de pavimentos rodoviários: proposta de metodologia utilizando imagens hiperespectrais  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese No atual sistema de concessões rodoviária do Brasil ambos, concessionárias e agências reguladoras têm a missão de melhorar a qualidade dos pavimentos rodoviários no País. Tal situação requer a pesquisa e a identificação de novas ferramentas que facilitem o levantamento das condições dos pavimentos r [...] odoviários num tempo e custos menores que os métodos usuais. Recentemente, se verificou um grande aumento da disponibilidade de imagens de sensoriamento remoto com alta resolução espacial, seguindo uma tendência do mercado de novos satélites de sensoriamento remoto, e de sensores aerotransportados. De forma similar, imagens multi e hiperespectrais estão disponíveis tanto comercialmente quanto para a pesquisa científica. O artigo apresenta uma nova metodologia para a identificação das condições do asfalto em superfícies pavimentadas e uma classificação dos tipos de defeitos identificáveis a partir de imagens hiperespectrais adquiridas por sensores aerotransportados. O objetivo do artigo é o de mostrar que índices das condições das superfícies dos pavimentos asfaltados gerados via imagens hiperespectrais podem ser comparados com os indicadores vigentes, utilizados pela agência reguladora nacional. Abstract in english With the current system of concession roads in Brazil, both concessionaires and regulatory agents have been charged with improving the quality of the pavement on Brazilian highways. This situation requires the search for new tools that can facilitate the survey of pavement conditions in less time an [...] d at a lower cost than traditional methods. Recently, an increasing number of high-resolution spatial images have become available on the world market following the development of new remote sensing satellites and airborne sensors. Similarly, multispectral images and even hyperspectral images are now available commercially and for scientific research. The paper presents a new methodology for the identification of asphalted pavement surfaces condition and the classification of the main types of asphalt defects using hyperspectral images from airborne digital sensors. The objective of this study was to generate indexes of pavement conditions from images that can be compared with the indicators of pavement surface conditions already used by national regulatory agencies.

Marcos Ribeiro, Resende; Liedi Legi Bariani, Bernucci; José Alberto, Quintanilha.

2014-04-01

44

Permeable Pavement Research - Edison, New Jersey  

Science.gov (United States)

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

45

Application of image analysis to the identification and rating of road surface distress  

OpenAIRE

Numerical image analysis is used to detect narrow cracks on bituminous pavement. This problem is complicated because of the variable road aspect, which depends on coarseness textures, changing ambient lighting, presence of humidity and because of the poor contrast of the cracks with regard to road texture. The paper presents algorithms suited to detect random cracks edges in a noisy environment in three stages. The pre-treatment consisted mainly in applying a background correction to elimi...

Rasse, Catherine; Leemans, Vincent; Destain, Marie-france; Verbrugge, Jean-claude

2002-01-01

46

Mechanistic design concepts for conventional flexible pavements  

Science.gov (United States)

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

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

1985-02-01

47

MODELING PAVEMENT DETERIORATION PROCESSES BY POISSON HIDDEN MARKOV MODELS  

Science.gov (United States)

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

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

48

The Influence of Statistical Spatial Repeatabiliy on Remaining Pavement Life  

OpenAIRE

A road develops permanent deformation and fatigue damage because of the strains induced in its structure by surface loading and environmental change. A mechanistic-empirical approach is implemented here to simulate the deterioration of a pavement. A quarter car model is used to simulate pavement/vehicle dynamic interaction and a feedback mechanism is implemented after each run to update the pavement profile after the passage of each axle. In this way, the influence of Statistic...

O Brien, Eugene J.; Taheri, A.

2010-01-01

49

Hybrid green permeable pave with hexagonal modular pavement systems  

Science.gov (United States)

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.

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

2013-06-01

50

Hybrid green permeable pave with hexagonal modular pavement systems  

International Nuclear Information System (INIS)

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.h safety factor for daily life vehicles.

51

Assessment of porous asphalt pavement performance: hydraulics and water quality  

Science.gov (United States)

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 derived from that which is entering the stormwater treatment system in the adjacent parking lot. Since the facility is new, parking has been less intensive here, and influent concentrations will be adjusted down accordingly. Several wells have been installed in and around the facility. Screened intervals are at two levels; in the reservoir and beneath the facility. One well in the facility is continually monitored for basic water quality parameters (temperature, specific conductivity, pH, dissolved oxygen) and level, and is also sampled with an automated refrigerated sampler. Grab samples are collected from the other wells as a basis for comparison. Water samples are collected during several storm events and during interstorm periods to assess water quality treatment performance. The samples are analyzed for nutrients, metals, petroleum hydrocarbons, and pathogens. The potential for leaching of pollutants from the asphalt binder will also be assessed during these storm events. Water quality treatment performance is compared to those of several other studies. Updates on spring 2005 data are also included in the presentation.

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

2005-05-01

52

Reducing traffic noise with quieter pavements  

Science.gov (United States)

In recent years, interest has increased in the use of pavement type to reduce traffic noise. This has been driven by public concern over noise from freeways and state transportation agencies' interest in using pavement instead of sound walls to mitigate traffic noise. Beginnings of the recent interest go back to 1998 with the formation of the Institute for Safe, Quiet & Durable Highways at Purdue University and the initiation long-term research by the California Department of Transportation (Caltrans) on the effectiveness of quieter pavements. In 2002, the State of Arizona announced plans to overlay 115 miles of concrete freeway in the greater Phoenix area with a quieter asphalt rubber surface. This turned into the first Quiet Pavement Pilot Program in partnership between Federal Highway Administration (FHWA) and the Arizona Department of Transportation. Since that time, the FHWA in cooperation with the American Association of State Highway Transportation Agencies conducted a fact finding ``Scan'' tour in Europe to evaluate their quiet pavement technology and policy. This was followed by the first comparative tire/pavement noise testing in the US and Europe using the same procedures and test tires. The results, issues, and future directions surrounding these activities will be discussed.

Donavan, Paul

2005-09-01

53

Field Evaluation of Nondestructive Tests in Measuring the Pavement Layers Density  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was field evaluation of nondestructive devices in measuring the density of road layers. Density may be considered as a reliable criterion for evaluating pavement quality and has a high level of importance in that it can ensure the proper performance of pavement at least prior the period of life-time. At present time, the most current and also accurate method to determine in-situ density of asphalt mixture is core sample method, however it has some disadvantages. As well as being costly and time consuming, core sample method causes some distress on the pavement surface and it is not possible to repeat the test for a specific location. In view of this, some attempts were made to develop new methods as alternatives for core sample method. And as such, nondestructive tests have grown into a huge area over the last few years. These tests including nuclear and nonnuclear nondestructive tests do not have the limitations of core sample method. In this study, field evaluation in a new constructed part of a highway was conducted using pavement quality indicator (PQI301 and Troxler nuclear gauge (Model HS-5001EZ. According to the results of validation tests for nondestructive devices (PQI and Nuclear devices, PQI device has sufficient reliability to determine density of asphalt mixture layer but Nuclear device is not reliable to determine density. The obtained results from validation of nuclear device revealed that it has sufficient reliability to determine density of soil layers. Also it was found that the role of calibration procedure in obtaining correct readings From PQI device is highly critical.

H. Divandary

2010-01-01

54

Time domain backcalculation of pavement  

Science.gov (United States)

Falling weight deflectometor (FWD) has been frequently used to evaluate structural integrity of pavement. The device applies an impulsive force on the surface of pavement and measure surface deflections at several locations including the place of loading. Although the test is dynamic, the data is regarded as pseudo-static data. According to common practice, using the peak load and the corresponding peak deflections, layer moduli are estimated in a static domain such that the measured peak deflections coincide with the corresponding calculated deflections based on the assumption of the theory of linear elasticity. This paper presents a method to back calculate layer moduli in dynamic domain such that the histories of both measured and calculated responses corresponding to the impulsive force coincide. Pavement is modeled by an axisymmetric linear elastic system. FEM is utilized coupled with Ritz vector to reduce a matrix and thus to improve computational efficiency. The backcalculation algorithm used is the Gauss-Newton method coupled with a truncated singular value decomposition.

Matsui, Kunihito; Nishizawa, Tatsuo; Kikuta, Yukio

1998-03-01

55

Effect of induced deformation on NDT pavement evaluation  

Science.gov (United States)

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.

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

1999-02-01

56

A Framework for Quantification of Effect of Drainage Quality on Structural and Functional Performance of Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available Drainage quality is an important parameter which affects the highway pavement performance. Excessive water content in the pavement base, sub-base, and sub-grade soils can cause early distress and lead to a structural or functional failure of pavement. Thus, when selecting appropriate maintenance strategies the cost of pavement maintenance needs to be compared with the cost of improving the quality of drainage. Hence, there is a need to quantify the effect of various types of drainage quality on performance of the pavement. However, very few studies have investigated to what extent quality of drainage affects the performance of pavement. Therefore, this study identifies a simple framework for quantification of effect of drainage quality on structural as well as functional performance of the pavement. The proposed framework presents the structural and functional performance of the pavement is predicted in terms of deflection and roughness respectively. It is expected that this study will useful to reduce the maintenance cost of highway pavement system and hence will be useful to preserve huge highway network in India.

Jitendra Gurjar, Pradeep Kumar Agarwal, Manoj Kumar Sharma

2013-07-01

57

Modeling the Pavement Present Serviceability Index of Flexible Highway Pavements Using Data Mining  

Directory of Open Access Journals (Sweden)

Full Text Available The term present serviceability was adopted to represent the momentary ability of pavement to serve traffic and the performance of the pavement was represented by its serviceability history in conjunction with its load application history. Serviceability was found to be influenced by longitudinal and transverse profile as well as the extent of cracking and patching. The amount of weight to assign to each element in the determination of the over-all serviceability is a matter of subjective opinion. In the present study, a regression tree model has been presented for determining flexible pavement surface layer thickness. The model, RT was selected as estimating method. Results show that wearing course thickness of flexible pavement regression values of the regression tree model is better than that of the AASHO model. This approach can be easily and realistically performed to solve the optimization problems which do not have a formulation or function about the solution.

Serdal Terzi

2006-01-01

58

Structural response of LVR flexible pavements at Mn/ROAD project  

Energy Technology Data Exchange (ETDEWEB)

Pavement surface deflection basins provide valuable information for the structural evaluation of flexible pavements. Surface deflection measurements are rapid, inexpensive, and nondestructive and are used frequently as an indicator of pavement structural capability and performance potential. In this study, falling weight deflectometer testing results on the conventional flexible pavements (asphalt concrete surface, granular base/subbase) and aggregate-surface/surface-treated test sections in the low-volume road loop at the Minnesota Road Research Project (Mn/ROAD) were analyzed to evaluate the effect of granular material quality on the pavement structural response. Asphalt concrete (AC) modulus and subgrade ``break-point`` modulus were back-calculated using algorithms previously developed at the University of Illinois. The surface deflections were normalized to the same AC modulus and subgrade modulus. The analyses show a limited effect of granular material quality on the pavement deflection response in the case of conventional flexible pavements. Because of higher granular layer stresses, the granular material quality effects on the pavement surface deflection response of surface-treated/aggregate-surface pavements are significant. Increased AC thickness reduces the effect of granular base quality on the pavement deflection response.

Garg, N.; Thompson, M.R. [Univ. of Illinois, Urbana, IL (United States). Dept. of Civil Engineering

1999-05-01

59

Psychological Distress  

Science.gov (United States)

... of use of medications taken for depression, anxiety, schizophrenia, dementia, or bipolar disorder ? Lack of interest in ... managing psychological distress in persons with multimorbidity. International Journal of Psychiatry in Medicine ;2007;37(1):pages ...

60

Pervious Pavement System Evaluation  

Science.gov (United States)

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

61

Dynamic pavement deflection  

Science.gov (United States)

Dynamic pavement deflection measurements for bituminous concrete pavements of two and three-quarter, five and seven-eights, and seven and one-half inches in thickness under moving axle loads of 15,000, 18,000, and 22,000 pounds were obtained at speeds of 10, 25 and 45 miles per hour. The results were analyzed and compared to Benkelman beam measurements. The data indicate that slow moving loads have greater adverse effect (larger deflections) on the pavement than the high speed loads. The results also show that the bituminous pavement undergoes numerous vertical fluctuations and bending as the front and rear axles approached the point of measurement. The magnitude of the vertical displacement was measured via the means of an accelerometer and double integrator. When values of the dynamic deflections were in the magnitude of 0.07 through 0.10 inches, there was evidence of pavement failure. When the deflection values were above 0.10 inches pavement failures were distinct.

Rand, D. W.; Jacobs, K. M.

1981-06-01

62

A high speed profiler based slab curvature index for jointed concrete pavement curling and warping analysis  

Science.gov (United States)

One of the biggest gaps of missing knowledge between accurate structural modeling of concrete pavement slab behavior and real pavement behavior is accounting for slab warping (locked-in curvature and moisture gradient effects) and curling (temperature gradient effects). Curling and warping are curvatures that can be present in a PCC slab that can cause corners and edges, or mid panel, of the slab to lift off of the ground resulting in relatively high deflection and stress in the system. The least understood type of curvature in slabs is apparent locked-in curvature, which can become excessive and control the overall behavior of the pavement system. This project is focused on quantifying slab curvatures and the effects of apparent locked-in curvature on the behavior and long-term performance of pavement systems. A high-speed profile analysis technique for detecting the amount of slab curvatures along pavement wheel paths is described. This signal processing technique can detect relatively small curvature variations in high-speed pavement elevation profiles obtained at normal highway operating speeds using special vehicles. A resulting curvature detection algorithm is applied to the Federal Highway Administration (FHWA) Long Term Pavement Performance (LTPP) database high-speed pavement profiles for jointed concrete pavements. The range and nature of slab curvatures detected in the profiles is described. The calculated locked-in curvature at the various pavement sites is compared to LTPP database information to evaluate curvature effects on pavement deterioration rates and the relation between site parameters and locked-in curvature. The significance of slab curvature is shown through statistics and predictive models developed for various pavement distress modes. It is shown that the amount of curvature locked into concrete slabs is one of the strongest factors in the FHWA LTPP data correlated to deterioration of pavements. This study shows that preventing locked-in slab curvature should be a top priority for PCC slabs in highway applications. The profile analysis routine and distress prediction models developed will be valuable tools for pavement designers, managers, and researchers.

Byrum, Christopher Ronald

63

Pavement Evaluation and Maintenance Decisions Based on Fuzzy Inference Systems  

Directory of Open Access Journals (Sweden)

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.

Beltrán-Calvo Gloria Inés

2014-07-01

64

Classificação híbrida: pixel a pixel e baseada em objetos para o monitoramento da condição da superfície dos pavimentos rodoviários / Hybrid classification: pixel by pixel and object based to monitor the surface conditions of road pavements  

Scientific Electronic Library Online (English)

Full Text Available Monitorar a condição de uso de toda a extensão das rodovias brasileiras é tarefa dispendiosa e demorada. Este trabalho trata de novas técnicas que permitem o levantamento da condição da superfície dos pavimentos rodoviários de forma ágil utilizando imagens hiperespectrais de sensor digital aeroembar [...] cado. Nos últimos anos, um número crescente de imagens de alta resolução espacial tem surgido no mercado mundial com o aparecimento dos novos satélites e sensores aeroembarcados de sensoriamento remoto. Propõe-se uma metodologia para identificação dos pavimentos asfálticos e classificação das principais ocorrências dos defeitos na superfície do pavimento. A primeira etapa da metodologia é a identificação da superfície asfáltica na imagem, utilizando uma classificação híbrida baseada inicialmente em pixel e depois refinada por objetos. A segunda etapa da metodologia é a identificação e classificação das ocorrências dos principais defeitos nos pavimentos flexíveis que são observáveis nas imagens de alta resolução espacial. Esta última etapa faz uso intensivo das novas técnicas de classificação de imagens baseadas em objetos. O resultado final é a geração de índices da condição da superfície do pavimento a partir das imagens que possam ser comparados com os indicadores vigentes da condição da superfície do pavimento já normatizados pelos órgãos competentes no país. Abstract in english Monitoring every Brazilian road use condition is an expensive and time consuming task. This research deals with new techniques which will yield a quick survey of road surface pavement condition by using hyperspectral images from airborne remote sensing. Recently, an increasing number of images with [...] high spatial resolution has emerged on the world market with the advent of new remote sensing satellites and airborne sensors. Hyperspectral images from digital airborne sensor have been used in this work. A new identification methodology for a pavement surface and also for classification of the main defects of the surface has been devised. The first step of the methodology is the identification of the asphalt surface in the image, by using hybrid classification based on pixel initially and then improved by objects. The second step of the methodology is the identification and classification of the main defects of pavement surface that are observable in high spatial resolution imagery. This step makes intensive use of new techniques for classification of images based on objects. The goal is the generation of pavement surface condition index from the images which can be compared to quality index of pavement surface already managed by the regulatory agency in the country.

Marcos Ribeiro, Resende; Liedi Légi Barianni, Bernucci; José Alberto, Quintanilha.

2012-09-01

65

Formulação probabilística para análise de tabuleiros de pontes rodoviárias com irregularidades superficiais Probabilistic formulation for the analysis of highway bridge decks with irregular pavement surface  

Directory of Open Access Journals (Sweden)

Full Text Available Apresenta-se uma metodologia de análise com o objetivo de avaliarem-se os efeitos de irregularidades superficiais no tabuleiro sobre o comportamento de pontes rodoviárias submetidas à passagem de veículos. A resposta do sistema veículo-estrutura é obtida no domínio da freqüência segundo modelo probabilístico. Simula-se o tabuleiro das pontes com modelo de elementos finitos unidimensionais com massas discretizadas nos nós, o veículo por um sistema de massas, molas e amortecedores, e as irregularidades da pista são definidas por modelo não-determinístico com base na densidade espectral do perfil do pavimento. O carregamento é constituído por uma sucessão infinita de veículos igualmente espaçados deslocando-se com velocidade constante sobre o tabuleiro e a atenção é concentrada na fase permanente da resposta do sistema. Deduzem-se as expressões das densidades espectrais dos elementos da resposta a partir da densidade espectral do perfil irregular do pavimento e integram-se numericamente tais expressões para se chegar às médias quadráticas desses elementos. Observa-se a resposta do modelo matemático, com base em uma ponte rodoviária de concreto armado simplesmente apoiada, com seção tipo caixão e inércia constante, em termos de deslocamentos e esforços nas seções onde ocorrem os efeitos máximos. As conclusões versam sobre a adequação da metodologia desenvolvida e do modelo matemático empregado.An analysis methodology is proposed to evaluate the dynamical effects, displacements and stresses, on highway bridge decks, due to vehicles crossing on the rough pavement surfaces defined by a probabilistic model. To this purpose, the methodology is developed to evaluate the vehicle-structure response under a full probabilistic formulation, running in the frequency domain. The mathematical model assumes a finite element representation of the beam like deck and the vehicle simulation uses concentrated parameters of mass, stiffness and damping. The deck surface roughness is defined by a well known power spectrum density of road pavement profiles. The moving load is formed by an infinite succession of equally spaced vehicles moving with constant velocity. Only steady-state response is considered. Response data are produced on concrete box girder elements assembled as a simple beam. Conclusions are concerned with the fitness of the developed analysis methodology and the mathematical model adequacy.

José Guilherme Santos da Silva

1999-09-01

66

Formulação probabilística para análise de tabuleiros de pontes rodoviárias com irregularidades superficiais / Probabilistic formulation for the analysis of highway bridge decks with irregular pavement surface  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Apresenta-se uma metodologia de análise com o objetivo de avaliarem-se os efeitos de irregularidades superficiais no tabuleiro sobre o comportamento de pontes rodoviárias submetidas à passagem de veículos. A resposta do sistema veículo-estrutura é obtida no domínio da freqüência segundo modelo proba [...] bilístico. Simula-se o tabuleiro das pontes com modelo de elementos finitos unidimensionais com massas discretizadas nos nós, o veículo por um sistema de massas, molas e amortecedores, e as irregularidades da pista são definidas por modelo não-determinístico com base na densidade espectral do perfil do pavimento. O carregamento é constituído por uma sucessão infinita de veículos igualmente espaçados deslocando-se com velocidade constante sobre o tabuleiro e a atenção é concentrada na fase permanente da resposta do sistema. Deduzem-se as expressões das densidades espectrais dos elementos da resposta a partir da densidade espectral do perfil irregular do pavimento e integram-se numericamente tais expressões para se chegar às médias quadráticas desses elementos. Observa-se a resposta do modelo matemático, com base em uma ponte rodoviária de concreto armado simplesmente apoiada, com seção tipo caixão e inércia constante, em termos de deslocamentos e esforços nas seções onde ocorrem os efeitos máximos. As conclusões versam sobre a adequação da metodologia desenvolvida e do modelo matemático empregado. Abstract in english An analysis methodology is proposed to evaluate the dynamical effects, displacements and stresses, on highway bridge decks, due to vehicles crossing on the rough pavement surfaces defined by a probabilistic model. To this purpose, the methodology is developed to evaluate the vehicle-structure respon [...] se under a full probabilistic formulation, running in the frequency domain. The mathematical model assumes a finite element representation of the beam like deck and the vehicle simulation uses concentrated parameters of mass, stiffness and damping. The deck surface roughness is defined by a well known power spectrum density of road pavement profiles. The moving load is formed by an infinite succession of equally spaced vehicles moving with constant velocity. Only steady-state response is considered. Response data are produced on concrete box girder elements assembled as a simple beam. Conclusions are concerned with the fitness of the developed analysis methodology and the mathematical model adequacy.

José Guilherme Santos da, Silva; João Luís Pascal, Roehl.

1999-09-01

67

The impact of geology on the performance of a bituminous surfaced pavement—a case study from southeastern Nigeria  

Science.gov (United States)

One of the multi-million Naira dual carriageways in Nigeria, the Enugu-Port Harcourt expressway, has continued to experience failure at some sections, namely the stretches covering Lokpaukwu, Lokpanta, and Leru. This road section which, unlike others, does not respond to regular and routine maintenance, is concentrated on one geologic formation, the Eze Aku Shale which has been intruded by a dolerite sill. The emplacement of the dolerite sill had resulted in intense fracturing of the shales in the vicinity of the intrusions which includes portions of where the express road crosses. The road problem is most severe where the dolerite sill is traced right under and across the road. There is evidence from the study that the road problem is linked to the geological/hydrogeological conditions of the area. For example, the problematic section of the road is built on a considerably jointed, fractured and weathered shale formation as a subgrade. The subgrade ultimately has low bearing capacity. The road is almost at the foot of an escarpment where there is a concentration of natural groundwater discharge. Most of the discharge zones including natural water courses are now almost blocked resulting in increased groundwater storage and rise in water table under the highway pavement. This leads to fast deterioration of the base course materials. The dolerite sill, where it crosses the road, is less than 2 m below the grade level. It impedes vertical infiltration as well as lateral groundwater flow. Thus its position with respect to the highway grade elevation leads to an almost perpetual wetting of the base and sub-base materials.

Okagbue, C. O.; Uma, K. O.

68

Evaluation of pavement texture  

Science.gov (United States)

A system for pavement macrotexture measurement was evaluated. The system utilizes the principle of depolarization of reflected polarized light. The output of the system, the depolarized light number (DPN), is compared with other measures of pavement texture: sand-patch mean texture depth (MTD), British pendulum number (BPN), and outflow meter time (OFT) for 22 asphalt concrete sites and 5 portland cement concrete sites. The prediction of texture data from simultaneous measurements of ribbed and blank-tire skid resistance data was investigated. Using the two-tire data, it is possible to predict sand-patch mean texture depth (MTD) and Bristish pendulum number (BPN). Comparison of the two-tire data at accident sites demonstrates the potential to screen for wet weather accident sites by means of pavement surveys with the two tires.

Henry, J. J.; Wambold, J. C.; Huihua, X.

1984-10-01

69

Modeling Deflection Basin Using Neurofuzzy in Backcaluculating Flexible Pavement Layer Moduli  

Directory of Open Access Journals (Sweden)

Full Text Available Flexible pavement surface condition date play a principle role in the evaluation of pavement structural capacity and in the design of pavement rehabilitation programs. Flexible pavements are affected by moving vehicles, climate and other environmental factors. As a result of these factors, the pavement starts to deteriorate. In order to prevent further deterioration, a maintenance program should be carried out at right time and right places. For the determination of the structural carrying capacity of the pavement, non-destructive testing equipments are used. In such a process, the most important thing is to analyse the collected data. A backcalculation procedure is carried out for back-calculation elastic modules for each layer effective in the pavement life. The input data are usually restricted to the pavement surface deflection or its basin obtained by Nondestructive testing as the Falling Weight Deflectometer (FWD. Generally, linear elastic and finite element based programs are used for back-calculating, but they are both time consuming. It is also important to simulate deflection basin realistically in backcalculating pavement layer moduli. For this purpose, NeuroFuzzy method is used for simulation deflection basin during the course of this study. Results indicate that the NeuroFuzzy can be used for backcalculation of flexible pavement layer moduli with great improvement and accuracy.

Mehmet Saltan

2002-01-01

70

Pervious Pavement System Evaluation  

Science.gov (United States)

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

71

New structural systems for zero-maintenance pavements. Volume 2: Analysis of anchored pavements using ANSYS  

Science.gov (United States)

A set of procedures to evaluate the response of an anchored pavement subjected to vehicle static loads, moisture variation in the subgrade, and/or temperature variation through the surface of the pavement is presented. These procedures include two computer programs known as FEMESH and ANSYS. The FEMESH program generates rectangular meshes in either a two or three dimensional coordinate system for any prespecified number and spacing of nodes. The ANSYS program evaluates the stresses, strains, and the deflections at all elements in each material included in the analytical model.

Saxena, S. K.; Militsopoulos, S. G.

1980-08-01

72

Decision model in the laser scanning system for pavement crack detection  

Science.gov (United States)

Pavement crack detection plays an important role in the pavement maintaining and management. Recently, the laser scanning technique for pavement crack detection becomes more and more popular due to its ability of discriminating dark areas, which are not caused by pavement distress such as tire marks, oil spills, and shadows. However, this technique still bears some errors for pavement crack recognition errors, thus in the present work, the factors contributed to these errors in laser scanning system are first analyzed, and then a decision model for the laser scanning pavement crack detection system based on the hypothesis test is proposed. Experimental analyses and results show that this model not only allows us to build the relationship between the contribution factors and crack detection accuracy and to provide the criteria to compare the detection accuracy for the different roads, but also can be used to judge whether the crack exists with a reasonable number of deformed light stripes. Therefore, the proposed decision model can provide guidance on the pavement crack detection and has a practical value.

Sun, Xiaoming; Huang, Jianping; Liu, Wanyu

2011-12-01

73

New disclosures at pavement and maintenance treatment design on existent roads  

OpenAIRE

In the field of pavement design and maintenance treatment design on existent roads a significant progress was achieved in Slovenia in recent years. Condition of pavement surfaces and structures is continuously monitored and on roads with comparable deterioration (fatigue) similar maintenance treatments are designed. Essential knowledge, arising from years of experience in the field of pavement design and maintenance treatment design, are brought together in this work. The work is divided in t...

Cezar, Joz?ica

2007-01-01

74

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

OpenAIRE

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

Yueqin Hou; Nanxiang Zheng; Yiluo Zhang

2013-01-01

75

The study of road surface micro-texture's effects for the pavement's decontamination by high pressure water washing  

International Nuclear Information System (INIS)

In the result of “decontamination technical demonstration project” by Ministry of the Environment, it has became clear that the effect variation is larger in high pressure water washing method, compared with others in road surface decontamination technology. In this study, we have hypothesized the fact at the difference of micro-texture of the road surface, by carrying out high pressure water washing method in different kinds of road surfaces and verified the relation between washing efficiency and micro-texture road surface. Positive correlation has admitted between the washing number of times and radiation reduction rate and the trend of primary regression equation (i.e. radiation reduction rate per washing time) is indicating that decreasing tendency of radiation carried by the increasing of micro-texture of the road surface. Here, we proposed the method to estimated essential washing number of times to achieve the targeted radiation reduction rate from the relation of that trend and micro-texture of the road surface. (author)

76

PAVEMENT CRACKING DETECTION USING AN ANISOTROPY MEASUREMENT  

OpenAIRE

Automatic pavement cracking detection is a part of road maintenance and rehabilitation strategies. Cracks detection is one of the main features used by road authorities to manage efficiently its networks. Different systems are available to perform road analysis. We give a short description of some of them. Apparatus which was used to provide our images is described with more details. Road surface is made using randomly organized aggregates which can have different sizes. Scanned pictures of t...

Nguyen, Tien Sy; Begot, Ste?phane; Duculty, Florent; Bardet, Jean-christophe; Avila, Manuel

2010-01-01

77

Photocatalytic pavement blocks. Air purification by pavement blocks. Final results of the research at BRRC  

International Nuclear Information System (INIS)

The use of materials can influence to a large extent the environmental impact of traffic and of road infrastructure. Especially in urban areas, where the risk on smog formation during hot summer days is high, the use of photocatalytic pavement blocks can reduce the air pollution significantly. A project on environmental friendly concrete pavement blocks is conducted at the Belgian Road Research Centre. The use of photocatalytic material in the surface of pavement blocks to obtain air purifying materials is investigated. In contact with light, TiO2 as photocatalyst, is able to reduce the NO and NO2 content in the air, caused by the exhaust of traffic. The efficiency is tested on pavement blocks, but the technique can as well be applied on other road elements (e.g. noise reducing walls, linear elements) or as a coating on new materials or existing structures. At the previous TRA conference in Gotenborgh, Sweden, the principle of photocatalysis was presented. In this paper, emphasis will be put on the final results of the 4-year project obtained in laboratory as well as on site at the Leien of Antwerp (10,000 m2). The results indicate a durable efficiency towards NOx reduction, which is in favour for the diminishing of the risk on ozone formation. However, the precise translation from the laboratory towards the site is still in question. The results obtained during the project are discussed in this paper

78

Nondestructive testing of pavements and pavement bases (a bibliography with abstracts). Report for 1964--Dec 1975  

International Nuclear Information System (INIS)

Eighty references on nondestructive methods for quality assurance of pavements and pavement bases are presented. Vibration, nuclear activation, radiometry, and acoustic detection are among the various techniques employed

79

Permanent deformation of flexible pavements  

Science.gov (United States)

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

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

1980-06-01

80

Pervious Pavement System Evaluation- Abstract  

Science.gov (United States)

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

81

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

Science.gov (United States)

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

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

2014-06-15

82

Spills on Flat Inclined Pavements  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2004-03-01

83

Acute respiratory distress syndrome  

Science.gov (United States)

Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition that prevents enough oxygen from getting to the ... and into the blood. Infants can also have respiratory distress syndrome .

84

Analysis of Pavement for National Highway-N.H.1  

Directory of Open Access Journals (Sweden)

Full Text Available Rigid pavements are those which posses note worthy flexural strength or flexural rigidity. The stresses are not transferred from grain to grain to the lower layers as in the ease of flexible pavements layers the rigid pavements are made of Portland cement concrete-either plain, reinforced or prestressed concrete[1]. This paper shows the required to evaluate the strength characteristics of the soil subgrade, this helps the designer to adopt the suitable values of the strength parameter for design purposes and in case this supporting layer does not come upto the expectations, the same is treated or conditioned to suit the requirementsThe plain cement concrete slabs are expected to take up about 40 kg/cm2 flexural stress. As the rigid pavements slab has tensile strength, tensile stresses are developed due to the bending of the slab under wheel load and temperature variations thus the type of stress develop and their distribution within the cement concrete slab are quit different. The rigid pavement does not get deformed to the shape of the lower surface as it can bridge the minor variation of lower layer[2].

Arvind Dewangan

2012-02-01

85

Design of Rigid and Flexible Pavements by Various Methods & Their Cost Analysis of Each Method  

Directory of Open Access Journals (Sweden)

Full Text Available Highway and pavement design plays an important role in the DPR projects. The satisfactory performance of the pavement will result in higher savings in terms of vehicle operating costs and travel time, which has a bearing on the overall economic feasibility of the project. This paper discusses about the design methods that are traditionally being followed and examines the “Design of rigid and flexible pavements by various methods & their cost analysis by each method”. Flexible pavement are preferred over cement concrete roads as they have a great advantage that these can be strengthened and improved in stages with the growth of traffic and also their surfaces can be milled and recycled for rehabilitation. The flexible pavements are less expensive also with regard to initial investment and maintenance. Although Rigid pavement is expensive but have less maintenance and having good design period. The economic part are carried out for the design pavement of a section by using the result obtain by design method and their corresponding component layer thickness. It can be done by drawing comparisons with the standard way and practical way. This total work includes collection of data analysis various flexible and rigid pavement designs and their estimation procedure are very much useful to engineer who deals with highways.

Saurabh Jain

2013-09-01

86

Pervious Pavement System Evaluation-Poster  

Science.gov (United States)

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

87

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

Science.gov (United States)

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

88

Making "Magic" Sidewalks of Pervious Pavement  

Science.gov (United States)

Students use everyday building materials—sand, pea gravel, cement and water—to create and test pervious pavement. They learn what materials make up a traditional, impervious concrete mix and how pervious pavement mixes differ. Groups are challenged to create their own pervious pavement mixes, experimenting with material ratios to evaluate how infiltration rates change with different mix combinations.

Water Awareness Research and Education (WARE) Research Experience for Teachers (RET),

89

Pavement Subgrade Performance Study in the Danish Road Testing Machine  

DEFF Research Database (Denmark)

Most existing pavement subgrade criteria are based on the AASHO Road Test, where only one material was tested and for only one climatic condition. To study the validity of these criteria and to refine the criteria a co-operative research program entitled the "International Pavement Subgrade Performance Study" was sponsored by the FHWA with American, Finnish and Danish partners. This paper describes the first test series which was carried out in the Danish Road Testing Machine (RTM).The first step in this program is a full scale test on an instrumented pavement in the Danish Road Testing Machine. Pressure gauges and strain cells were installed in the upper part of the subgrade, for measuring stresses and strains in all three directions. During and after construction FWD testing was carried out to evaluate the elastic parameters of the materials. These parameters were then used with the theory of elasticity to calculate the stresses and strains at the position of the gauges and to compare these values to the stresses and strains recorded under the rolling wheel load.Plastic strains resulting from 50 000 applications of each of two load levels (20 kN and 40 kN) were recorded, as well as the permanent deformation of the pavement surface. A simple model describing the plastic strain has been developed.The test showed that currently used subgrade strain criteria are conservative if used with the measured strains in the subgrade. If used with strains calculated from FWD tests using linear elastic theory, however, the strain criteria seem to give a reasonably good prediction of the bearing capacity of the pavement.The differences between measured and theoretical values appear to be due to inhomogeneities in the pavement, to the non-linear elastic subgrade modulus and to a modulus gradient in the subgrade.

Ullidtz, Per; Ertman Larsen, Hans JØrgen

1997-01-01

90

Geo synthetic-reinforced Pavement systems  

International Nuclear Information System (INIS)

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)

91

Development of Pavement Temperature Contours for India  

Science.gov (United States)

The stress-strain response of the bituminous pavements is highly sensitive to temperature. To systematically analyze the pavement performance, it is necessary that one understands the variation of pavement temperature spatially and temporally during the life time of a pavement. In this investigation, historic air temperature data for 37 locations across India was collected. Using this database, pavement temperature data was predicted by an appropriate air temperature-pavement temperature model. High and low temperature pavement temperature contours were generated for the first time for India. It was seen that the locations spanning from Srinagar to Madhya Pradesh and Rajasthan to Orissa were extremely critical. The minimum temperature in these locations was 10 C and the maximum temperature was around 68 C. Clearly such information is necessary when making choice of binder grade and bituminous layer thickness.

Nivitha, M. R.; Krishnan, J. M.

2014-06-01

92

The distress premium puzzle  

OpenAIRE

Fama and French (1992) suggest that the positive value premium results from risk of financial distress. However, recent empirical research has found that financially distressed firms have lower stock returns, using empirical estimates of default probabilities. This paper reconciles the positive value premium and the negative distress premium in a model that decouples actual and risk-neutral default probabilities. Moreover, in agreement with the data, firms with higher bond yields have higher ...

Ozdagli, Ali K.

2010-01-01

93

The Concrete and Pavement Challenge  

Science.gov (United States)

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…

Roman, Harry T.

2012-01-01

94

Cooler reflective pavements give benefits beyond energy savings: durability and illumination  

International Nuclear Information System (INIS)

City streets are usually paved with asphalt concrete because this material gives good service and is relatively inexpensive to construct and maintain. We show that making asphalt pavements cooler, by increasing their reflection of sunlight, may lead to longer lifetime of the pavement, lower initial costs of the asphalt binder, and savings on street lighting and signs. Excessive glare due to the whiter surface is not likely to be a problem

95

Superfícies estriadas no embasamento granítico e vestígio de pavimento de clastos neopaleozóicos na região de Salto, SP Neopaleozoic striated surfaces in the granitic basement and clast pavement remains of Salto, SP  

Directory of Open Access Journals (Sweden)

Full Text Available Nas proximidades da Cerâmica Guaraú, localizada a sudoeste da cidade de Salto, Estado de São Paulo, dois afloramentos de granito, distantes algumas dezenas de metros um do outro, exibem superfícies estriadas neopaleozóicas. Essas superfícies estão em contato com diamictitos do Subgrupo Itararé. As estrias correspondem a sulcos subparalelos com espaçamento e profundidade milimétrica, possuindo uma direção média de N48°W e mergulhos variando entre 12° e 42° para SE. As feições observadas e a sua associação com diamictitos indicam uma origem por abrasão glacial devido ao movimento de massas de gelo de sudeste para noroeste. A aproximadamente 1,8 km a este da cidade de Salto foi encontrado, no topo de afloramentos de granito, material inconsolidado contendo abundantes clastos de quartzito facetados e estriados. Esses clastos foram interpretados como vestígios de um pavimento de castos.Near Guaraú Ceramic, localized southwest of Salto city in the State of São Paulo, two granite outcrops, distant some tens of meters from each other, display Neopaleozoic striated surfaces. These surfaces are in contact with diamictites from the Itararé Subgroup. The striae correspond to sub parallel grooves with millimetric spacing and depth, oriented about N48E and dipping 12° to 42° towards SE. Observed features and association with diamictites indicate an origin by glacial abrasion due to ice movement from southeast towards northwest. About 1.8 km east of Salto, unconsolidated material containing flat-iron-shaped and striated clasts was found on top of granite outcrops, interpreted as clast pavement remains.

Annabel Pérez-Aguilar

2009-03-01

96

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

International Nuclear Information System (INIS)

The objective of this study is to evaluate the life cycle costs and market barriers associated with using reflective paving materials in streets and parking lots as a way to reduce the urban heat island effect. We calculated and compared the life cycle costs of conventional asphalt concrete (AC) pavements to those of other existing pavement technologies with higher reflectivity-portland cement concrete (PCC), porous pavements, resin pavements, AC pavements using light-colored chip seals, and AC pavements using light-colored asphalt emulsion additives. We found that for streets and parking lots, PCC can provide a cost-effective alternative to conventional AC when severely damaged pavements must be completely reconstructed. We also found that rehabilitating damaged AC streets and intersections with thin overlays of PCC (ultra-thin white topping) can often provide a cost-effective alternative to standard rehabilitation techniques using conventional AC. Chip sealing is a common maintenance treatment for low-volume streets which, when applied using light-colored chips, could provide a reflective pavement surface. If the incremental cost of using light-colored chips is low, this chip sealing method could also be cost-effective, but the incremental costs of light-colored chips are as of yet uncertain and expected to vary. Porous pavements were found to have higher life cycle costs than conventional AC in parking lots, but several cost-saving features of porous pavements fellt-saving features of porous pavements fell outside the boundaries of this study. Resin pavements were found to be only slightly more expensive than conventional AC, but the uncertainties in the cost and performance data were large. The use of light-colored additives in asphalt emulsion seal coats for parking lot pavements was found to be significantly more expensive than conventional AC, reflecting its current niche market of decorative applications. We also proposed two additional approaches to increasing the reflectivity of conventional AC, 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

97

Modeling the Deflection Basin of Flexible Highway Pavements by Gene Expression Programming  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, Gene Expression Programming (GEP is used in modeling the deflection basins measured on the surface of the flexible pavements. Backcalculation of the pavement layer moduli are well-accepted procedures for the evaluation of the structural capacity of pavements. The ultimate aim of the backcalculation process from Nondestructive Testing (NDT results is to estimate the pavement material properties. Using backcalculation analysis, in situ material properties can be backcalculated from the measured field data through appropriate analysis techniques. In order to backcalculate reliable moduli, deflection basin must be realistically modeled. In this study, GEP was used to model the deflection basin characteristics. Experimental deflection data groups from NDT are used to show the capability of the GEP approach in modeling the deflection bowl. This approach can be easily and realistically performed to solve the problems which do not have a formulation or function about the solution.

Serdal Terzi

2005-01-01

98

Adaptive road crack detection system by pavement classification.  

Science.gov (United States)

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. PMID:22163717

Gavilán, Miguel; Balcones, David; Marcos, Oscar; Llorca, David F; Sotelo, Miguel A; Parra, Ignacio; Ocaña, Manuel; Aliseda, Pedro; Yarza, Pedro; Amírola, Alejandro

2011-01-01

99

Adaptive Road Crack Detection System by Pavement Classification  

Science.gov (United States)

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. PMID:22163717

Gavilán, Miguel; Balcones, David; Marcos, Oscar; Llorca, David F.; Sotelo, Miguel A.; Parra, Ignacio; Ocaña, Manuel; Aliseda, Pedro; Yarza, Pedro; Amírola, Alejandro

2011-01-01

100

Adaptive Road Crack Detection System by Pavement Classification  

Directory of Open Access Journals (Sweden)

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.

Alejandro Amírola

2011-10-01

101

Effects of thermal properties on temperature and moisture profiles and the performance of PCC pavements  

Directory of Open Access Journals (Sweden)

Full Text Available To understand the effects of thermal properties on temperature and the moisture profile in Portland cement concrete (PCC pavements, an Enhanced Integrated Climatic Model (EICM analysis was performed for a typical PCC pavement section in Louisiana. The EICM analysis showed that the temperature in the middle layer of PCC pavement decreased as thermal conductivity increased, and the temperature remained constant for higher thermal conductivity values. Temperature was measured at several depths of a concrete block embedded in soil and was compared to the temperature profile predicted by the EICM. Measured temperatures inside the concrete block were higher than the temperatures predicted by the EICM. The measured temperatures reached a peak hour temperature gradient on the hottest time of day, but the EICM model did not predict the peak hour temperature gradient. MEPDG analysis was performed to estimate the effect of thermal properties on the distress of PCC pavements. From the analysis it was found that thermal cracking increased with the decrease of thermal conductivity. It was also noticed that an Integrated Climatic Model (ICM stability failure occurred for a set of thermal conductivity and heat capacity readings in the MEPDG analysis. A passing line is proposed to separate the ICM stability passing zone and failure zone.

Upender Kodide M.S.

2011-12-01

102

Mathematical failure-theory (MFT methodology in pavement management system for rehabilitation and repair methods selection  

Directory of Open Access Journals (Sweden)

Full Text Available Pavement rehabilitation and repair methods selection is one of the key issues many road organizations and researchers have occupied. Not only road management cost but also road user’s cost and cost for inhabitants and community should be included in the life cycle cost in order to help infrastructure investment judgment. Thus in estimating life cycle cost, Pavement rehabilitation and repair methods selection is essential even if technological capabilities of evaluation are not sufficient. In order for Pavement Management Systems (PMS to be effective, they must be based on a reliable, statistically sound means for the rehabilitation and repair methods that are present on the system. To make sensible life cycle cost decisions in design and rehabilitation, pavement engineers must be able to account for distress phenomena and repair methods. This paper will present a Mathematical Failure-Theory (MFT methodology for incorporating statistical and probabilistically Factors into life cycle cost analysis and PMS. This approach gives the engineer the ability to statistically and probability consider different rehabilitation and repair method and statistically and probability factors in computing the life cycle costs for rehabilitation and repair methods selection.

Fereidoon Moghadas Nejad

2009-04-01

103

Maintenance methods for continuously reinforced concrete pavements  

Science.gov (United States)

Test sections were constructed on a section of 1-65 south of Indianapolis, Indiana to evaluate various maintenance techniques that might be adopted for this type of pavement. The road was stratified into similar sections using deflection, cracking and breakup as selection criteria. Maintenance methods used included concrete shoulders, undersealing, asphalt concrete overlay, subdrains at the pavement edge and various combinations of these methods. In every case the pavement was patched prior to installation of the maintenance.

Yoder, E. J.

1980-05-01

104

Comparative field permeability measurement of permeable pavements using ASTM C1701 and NCAT permeameter methods.  

Science.gov (United States)

Fully permeable pavement is gradually gaining support as an alternative best management practice (BMP) for stormwater runoff management. As the use of these pavements increases, a definitive test method is needed to measure hydraulic performance and to evaluate clogging, both for performance studies and for assessment of permeability for construction quality assurance and maintenance needs assessment. Two of the most commonly used permeability measurement tests for porous asphalt and pervious concrete are the National Center for Asphalt Technology (NCAT) permeameter and ASTM C1701, respectively. This study was undertaken to compare measured values for both methods in the field on a variety of permeable pavements used in current practice. The field measurements were performed using six experimental section designs with different permeable pavement surface types including pervious concrete, porous asphalt and permeable interlocking concrete pavers. Multiple measurements were performed at five locations on each pavement test section. The results showed that: (i) silicone gel is a superior sealing material to prevent water leakage compared with conventional plumbing putty; (ii) both methods (NCAT and ASTM) can effectively be used to measure the permeability of all pavement types and the surface material type will not impact the measurement precision; (iii) the permeability values measured with the ASTM method were 50-90% (75% on average) lower than those measured with the NCAT method; (iv) the larger permeameter cylinder diameter used in the ASTM method improved the reliability and reduced the variability of the measured permeability. PMID:23434738

Li, Hui; Kayhanian, Masoud; Harvey, John T

2013-03-30

105

Runoff on Pavements of Soil-Cement Blocks – an Experimental Boarding  

Directory of Open Access Journals (Sweden)

Full Text Available The article evaluates the reduction of runoff in pavements constructed with rectangular blocks of soil-cement. The tests were conducted in a pilot pavement built with soil-cement blocks, seated in a metal box of 50 cm × 50 cm (area = 2500 cm2, with declivities of 1%, 3% and 5%. Mean intensities of 76.9 mm / I 117.7 mm / h were used, values close to the intensities calculated by intensity-frequency-duration (i-f- -d equation of the city of Salvador, Brazil, for return periods of 2 and 5 years, respectively. The medium runoff coefficient was C = 0.61, this value is close to the coefficient of pavement with rectangular blocks (C = 0.6 and it has a lower value than the coefficient for concrete block pavement (C = 0.78. On the other hand, considering that areas with more than 2500 cm2 are constituted by coupling of area units of 50 cm × 50 cm, the splash losses are part of the runoff, obtaining the coefficient Csuperficial + splashing, which showed values in the 0.74 to 0.89 range, these values were found close to the coefficient of concrete block pavement (C = 0.78 and below the concrete pavement (C = 0.95, respectively, but factors such as displacement time of runoff on surface, depressions on the surface, roughness of pavement, evaporation and others, should reduce this value. Then, the pavement of soil-cement blocks can be considered in the category of semi-permeable for the area size used.

Zegarra-Tarqui Jorge Luis

2015-01-01

106

Generation mechanisms of tire-pavement noise  

Science.gov (United States)

Tire-pavement noise is the dominant source of traffic noise at highway speeds. It is the result of a combination of several noise generation mechanisms, including tire carcass vibration and tread block vibration. Because multiple mechanisms are involved, it is difficult to predict the effects of changes in pavement parameters on tire-pavement noise. In this research, a set of experimental techniques were developed to decompose a measured tire-pavement noise spectrum into a set of constituent spectra relating to each generation mechanism. Three principal mechanisms were identified: treadband vibration, sidewall vibration, and tangential tread block vibration. By combining the constituent spectra associated with these mechanisms, it was possible to accurately predict the total tire-pavement noise spectrum. The constituent spectra were fit to tire-pavement noise data measured on asphalt and concrete pavements at highway speeds. It was found that the constituent spectra fit the measured data well, and a two-parameter model was developed to predict tire-pavement noise levels from pavement texture data.

Dare, Tyler P.

107

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

Energy Technology Data Exchange (ETDEWEB)

The objective of this study is to evaluate the life cycle costs and market barriers associated with using reflective paving materials in streets and parking lots as a way to reduce the urban heat island effect. We calculated and compared the life cycle costs of conventional asphalt concrete (AC) pavements to those of other existing pavement technologies with higher reflectivity-portland cement concrete (PCC), porous pavements, resin pavements, AC pavements using light-colored chip seals, and AC pavements using light-colored asphalt emulsion additives. We found that for streets and parking lots, PCC can provide a cost-effective alternative to conventional AC when severely damaged pavements must be completely reconstructed. We also found that rehabilitating damaged AC streets and intersections with thin overlays of PCC (ultra-thin white topping) can often provide a cost-effective alternative to standard rehabilitation techniques using conventional AC. Chip sealing is a common maintenance treatment for low-volume streets which, when applied using light-colored chips, could provide a reflective pavement surface. If the incremental cost of using light-colored chips is low, this chip sealing method could also be cost-effective, but the incremental costs of light-colored chips are as of yet uncertain and expected to vary. Porous pavements were found to have higher life cycle costs than conventional AC in parking lots, but several cost-saving features of porous pavements fell outside the boundaries of this study. Resin pavements were found to be only slightly more expensive than conventional AC, but the uncertainties in the cost and performance data were large. The use of light-colored additives in asphalt emulsion seal coats for parking lot pavements was found to be significantly more expensive than conventional AC, reflecting its current niche market of decorative applications. We also proposed two additional approaches to increasing the reflectivity of conventional AC, 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.

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

2001-11-21

108

Predicting Financial Distress and the Performance of Distressed Stocks  

OpenAIRE

In this paper, we consider the measurement and pricing of distress risk.We present a model of corporate failure in which accounting and market-based measures forecast the likelihood of future financial distress. Our best model is more accurate than leading alternative measures of corporate failure risk.We use our measure of financial distress to examine the performance of distressed stocks from 1981 to 2008. We find that distressed stocks have high stock return volatility and high market beta...

Campbell, John Y.; Hilscher, Jens Dietrich; Szilagyi, Jan

2011-01-01

109

Effects of impervious pavements on reducing runoff in an arid urban catchment  

Science.gov (United States)

The progressive urbanization of US arid and semi-arid southwestern territories has transformed undeveloped aridlands into dynamic, radially expanding metropolitan centers. As these mature, infill development further reduces undeveloped area, inversely coupling surface imperviousness to infiltration rates, with a subsequent increase in runoff generation. Intensified runoff carries undesirable environmental consequences, magnifying urban flooding events and concentrations, transport, and propagation of contaminants. Pervious pavements offer one potential solution for decreased urban infiltration. At present, the application potential of pervious pavements as an effective urban infiltration management tool exceeds its exploitation. While entirely eliminating urban Total Impervious Area is not a feasible solution, pervious pavements significantly reduce Effective Impervious Area at costs competitive with traditional Best Management Practices. Previous research into pervious pavements has largely consisted of laboratory prototypes or small-scale field experiments, with a heavy bias towards parking lots. In this study we explore the effectiveness of pervious pavements in increasing infiltration, thus decreasing runoff volume during summer monsoonal and winter convective rainfall events in an 8 ha residential catchment in Scottsdale, Arizona. Analysis focuses on the interaction dynamics between surface area of pervious pavement application and its net effect on runoff response at the catchment level. Hydrological response was modeled using MAHLERAN (Model for Assessing Hillslope-Landscape Erosion, Runoff and Nutrients), a spatially explicit, event-based model, parameterized at a spatial resolution of 0.25 sq m. Data for model parameterization was obtained from analysis of aerial imagery and field-based monitoring of surface properties. The model was tested against measurements of flow at the catchment outlet for multiple rainfall events with total event rainfall ranging from 5 mm to 25 mm. Model testing shows total event discharge simulated well, although low Nash-Sutcliffe coefficients for events indicate a poor fit between the shape and timing of the modeled and monitored hydrograph, which we attribute to poor characterization of friction factors in urban catchments. Scenario-based model analysis tested catchment response to substitution of pervious for conventional pavement by percent and pavement-function scenarios. Results are consistent with previous findings in that short duration-high intensity storms trigger threshold infiltration capacity, past which pervious pavement damping of runoff volume levels off, approaching conventional levels. However at the modeled catchment scale, this initial damping represents a significant reduction in volume, peak flow velocity, and contaminant loading potential. Urban surface drainage networks concentrate and channel flow along roads: the capacity of pervious pavements to simultaneously increase infiltration directly at location of greatest runoff and mitigate inflow effects from remote points has compelling potential as a hydrologic and urban systems engineering tool.

Epshtein, O.; Turnbull, L.; Earl, S.

2011-12-01

110

Superfícies estriadas no embasamento granítico e vestígio de pavimento de clastos neopaleozóicos na região de Salto, SP / Neopaleozoic striated surfaces in the granitic basement and clast pavement remains of Salto, SP  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Nas proximidades da Cerâmica Guaraú, localizada a sudoeste da cidade de Salto, Estado de São Paulo, dois afloramentos de granito, distantes algumas dezenas de metros um do outro, exibem superfícies estriadas neopaleozóicas. Essas superfícies estão em contato com diamictitos do Subgrupo Itararé. As e [...] strias correspondem a sulcos subparalelos com espaçamento e profundidade milimétrica, possuindo uma direção média de N48°W e mergulhos variando entre 12° e 42° para SE. As feições observadas e a sua associação com diamictitos indicam uma origem por abrasão glacial devido ao movimento de massas de gelo de sudeste para noroeste. A aproximadamente 1,8 km a este da cidade de Salto foi encontrado, no topo de afloramentos de granito, material inconsolidado contendo abundantes clastos de quartzito facetados e estriados. Esses clastos foram interpretados como vestígios de um pavimento de castos. Abstract in english Near Guaraú Ceramic, localized southwest of Salto city in the State of São Paulo, two granite outcrops, distant some tens of meters from each other, display Neopaleozoic striated surfaces. These surfaces are in contact with diamictites from the Itararé Subgroup. The striae correspond to sub parallel [...] grooves with millimetric spacing and depth, oriented about N48E and dipping 12° to 42° towards SE. Observed features and association with diamictites indicate an origin by glacial abrasion due to ice movement from southeast towards northwest. About 1.8 km east of Salto, unconsolidated material containing flat-iron-shaped and striated clasts was found on top of granite outcrops, interpreted as clast pavement remains.

Annabel, Pérez-Aguilar; Setembrino, Petri; Rafhael, Hypólito; Sibele, Ezaki; Paulo Alves de, Souza; Caetano, Juliani; Lena V.S., Monteiro; Francisco A., Moschini.

2009-03-01

111

Pervious Pavement System Evaluation-Paper  

Science.gov (United States)

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

112

23 CFR 972.208 - Federal lands pavement management system (PMS).  

Science.gov (United States)

... Federal lands pavement management system (PMS). In addition...the AASHTO's “Pavement Management Guide.”2 2 “Pavement Management Guide,” AASHTO...on mileages, functional classes, volumes, loadings,...

2010-04-01

113

23 CFR 971.208 - Federal lands pavement management system (PMS).  

Science.gov (United States)

... Federal lands pavement management system (PMS). In addition...the AASHTO's “Pavement Management Guide.” 1 1 “Pavement Management Guide,” AASHTO...depend on mileage, functional classes, volumes, loading,...

2010-04-01

114

The Implications of Financial Distress  

OpenAIRE

PURPOSE OF THE STUDY This thesis aims to be the first paper to study comprehensively the full implications of financial distress and its indirect costs. Specifically, I investigate whether financially distressed companies operationally underperform their more conservatively financed counterparts and whether the distressed companies engage in inefficient asset sales. This is the first paper to study the effects of financial distress as the earlier literature concentrates purely on the e...

Nevalainen, Riku

2010-01-01

115

Evaluation of base courses for flexible pavements  

Science.gov (United States)

Nineteen pavement sections monitored over a period of approximately ten years were evaluated to determine the influence of base course parameters on the performance of primary flexible pavement systems in Piedmont, North Carolina. The present serviceability rating concept was used as a measure of performance. The findings that indicate roughness measures are insensitive to changes in subjective performance and that present design procedures are adequate and probably conservative for the pavements studied. Bituminous concrete base courses are not necessarily structurally superior to coarse aggregate base courses, and Benkleman beam deflections are poor indicators of performance.

Mullen, W. G.; Barnes, B. D.

1981-02-01

116

Comparison Between 2-D and 3-D Stiffness Matrix Model Simulation of Sasw Inversion for Pavement Structure  

OpenAIRE

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-...

Rosidi, Sri Atmaja P.

2007-01-01

117

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

Science.gov (United States)

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 (?PAH8) 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 ?g 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.

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

118

Intra Partum Foetal Distress  

Directory of Open Access Journals (Sweden)

Full Text Available The occurrence of neonatal asphyxia at Baragwanath Hospital is a daily problem. The question was raised as to whether intra partum foetal distress, apgar scoring at birth and the biochemical analysis of blood acid base status from the chorionic arteries can predict any short-term neurological defects.

J Kubheka

1985-09-01

119

Measuring Financial Distress.  

Science.gov (United States)

How does one tell which higher education institutions should go out of business? The National Commission on the Financing of Post-Secondary Education took the view that financial distress was only in part a financial problem. An essential key to the problem is a determination of the financial impact on educational objectives. Institutional…

Jenny, Hans

120

Tester for Distress Beacons  

Science.gov (United States)

Distress beacons on aircraft and boats checked for proper operation with aid of onboard monitor. Monitor mounted in aircraft cockpit or at wheel of boat. Connected to beacon electronics by cable. Monitor used with interface circuitry in beacon, which acts as buffer so that operation of beacon is not adversely affected if monitor is removed or if connecting cable is accidentally short circuited.

Wade, W. R.

1986-01-01

121

Nonlinear Responses of a Two Dimensional Vehicle-pavement System  

Directory of Open Access Journals (Sweden)

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

Shaohua Li

2013-09-01

122

GIS-based automated management of highway surface crack inspection system  

Science.gov (United States)

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 that can provide convenient and efficient pavement inspection and management.

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

2004-07-01

123

Modelación del envejecimiento de los pavimentos asfálticos con la metodología de la superficie de respuesta / Pavement Aging Model by Response Surface Modeling  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish En la presente investigación se realizó la modelación del envejecimiento de una carpeta asfáltica por medio de la Metodología de Superficie de Respuesta (MSR). Se elaboraron muestras cilíndricas tipo Marshall, que fueron colocadas en un horno bajo las condiciones de tiempo y temperatura establecidos [...] por las condiciones ambientales de la región geográfica donde se construyen pavimentos asfálticos con el AC-20 de la Refinería Ing. Antonio M. Amor, los cuales fueron codificados en la MSR, con esto se determinaron los modelos que predicen el cambio de la estabilidad Marshall (?L) y del flujo (?F), así como la volatilización del material (VM). Además, se extrajeron muestras cilíndricas de una carpeta asfáltica piloto para determinar el error de modelación, observando que el material volatilizado predicho por el modelo VM fue muy cercano al real, no así para los modelos de ?Ly ?F, posiblemente asociado a los factores ambientales que no fueron considerados al inicio de la investigación. Abstract in english In this work, surface course aging was modeled by Response Surface Methodology (RSM). The Marshall specimens were placed in a conventional oven for time and temperature conditions established on the basis of the environment factors of the region where the surface course is constructed by AC-20 from [...] the Ing. Antonio M. Amor refinery. Volatilized material (VM), load resistance increment (?L) and flow resistance increment (?F) models were developed by the RSM. Cylindrical specimens with real aging were extracted from the surface course pilot to evaluate the error of the models. The VM model was adequate, in contrast (?L) and (?F) models were almost adequate with an error of 20 %, that was associated with the other environmental factors, which were not considered at the beginning of the research.

L.E., Chávez-Valencia; C, Hernández-Barriga; A, Manzano-Ramírez.

2011-12-01

124

Pervious Pavement System Evaluation- Abstract 1  

Science.gov (United States)

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

125

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

Science.gov (United States)

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

Starke, P; Göbel, P; Coldewey, W G

2011-01-01

126

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

Science.gov (United States)

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

Junwei, Zhang; Jinping, Li; Xiaojuan, Quan

2013-01-01

127

Nondestructive testing of pavements and pavement bases. (a bibliography with abstracts). Report for 1964-Jan 78  

International Nuclear Information System (INIS)

Nondestructive methods for quality assurance of pavements and pavement bases are investigated in these Government-sponsored research reports. Vibration, nuclear activation, radiometry, and acoustic detection are among the various techniques employed. The updated bibliography contains 114 abstracts, 17 of which are new entries to the previous edition

128

The neonate in distress  

International Nuclear Information System (INIS)

Respiratory distress is a very common and yet non-specific symptom in neonates and young infants. It may be manifested clinically in many ways, including tachypnea, apnea, periodic respiratory, grunting, retractions, nasal flaring, and cyanosis. In many instances, the chest radiograph is diagnostic or at least suggestive of the diagnosis. This fact is important in determining surgical or medical conditions that require emergency therapy. Even if the chest film is normal, valuable information can be gained. This initial normal radiograph can be used as a baseline film in the face of further developing symptoms which, likewise, may have developing radiographic findings. In any event, the chest radiograph gives the clinician ''direction'' in his or her search for the cause of the patient's respiratory distress

129

Friction evaluation of concrete paver blocks for airport pavement applications  

Science.gov (United States)

The development and use of concrete paver blocks is reviewed and some general specifications for application of this type of pavement surface at airport facilities are given. Two different shapes of interlocking concrete paver blocks installed in the track surface at NASA Langley's Aircraft Landing Dynamics Facility (ALDF) are described. Preliminary cornering performance results from testing of 40 x 14 radial-belted and bias-ply aircraft tires are reviewed. These tire tests are part of a larger, ongoing joint NASA/FAA/Industry Surface Traction and Radial Tire (START) Program involving several different tire sizes. Both dry and wet surface conditions were evaluated on the two concrete paver block test surfaces and a conventional, nongrooved Portland cement concrete surface. Future test plans involving evaluation of other concrete paver block designs at the ALDF are indicated.

Yager, Thomas J.

1992-01-01

130

The effect of cracking on the deflection basin of flexible pavements  

Science.gov (United States)

Because of the rapid development of hardware and software during the past decade, it is now possible to use an analytical-empirical (or mechanistic) method of structural pavement evaluation on a routine basis. One reason for using this approach is the increased need for pavement maintenance and rehabilitation. To make the right choice from many potentially feasible maintenance and rehabilitation measures, the engineer must base his decision on a rational evaluation of the mechanical properties of the materials in the existing pavement structure. One of the parameters in terms of pavement response are the deflections; these are of interest to this particular study. The Falling Weight Deflectometer (FWD) has been developed specifically for the purpose of obtaining deflection measurements in order to determine the in-situ elastic moduli. The profile of the deflection at the surface of the pavement is known as the deflection basin, because it resembles a bowl-shaped depression. The magnitude of the deflections and the basin shape are functions of the number of layers making up the pavement cross section, their thicknesses, and their moduli values. A variety of multi-layered linear elastic pavement models are available for use at this present time. A general-purpose finite-element program called ANSYS developed by Swanson Analysis System is very powerful and is capable of solving a layered system such as the pavement. A finite element model was developed to study the effect of the crack on the predicted deflection bowls. A general-purpose finite-element program was used in this study due to its ability to solve this problem and because of the availability of the program. A hypothetical crack problem was assumed and modeled in different ways. The crack depth, crack width, and distance of the crack from the loading point were among the many parameters that were investigated. Considering the shape of the deflection basin, it is very important to study the effect of the crack on this bowl, when and where the cracks can be ignored, and when they would not play a significant effect. This study also addresses the importance of the field data and how the observed deflection basins compare with the predicted ones especially in aged pavements. This study has concluded that the location of a crack from the loading point is very significant to the deflection basin.

Omar, Hadi Mohamed

131

Financial Distress Prediction Using Distress Score as a Predictor  

OpenAIRE

Financial distress can be the reflection of corporation's management condition. Consequently the distress scoreof corporations should be considered as a new predictor variable in predicting the financial distress.The analysis of ROC curve, among the models employed to compare the effectiveness of different statisticalmodels, is often used in the fields of psychology and bio-physics in order to summarize the discriminatory of adiagnostic test and also to compare the performance of different mo...

Maryam Sheikhi; Mirfeiz Fallah Shams; Zeinab Sheikhi

2011-01-01

132

GPR in Nondestructive Quality Assurance of New Asphalt Pavements  

Science.gov (United States)

Mara Nord is an international cooperation project financed by Interreg IVA Nord funding program with partners from Finland, Sweden and Norway. One of the objectives in Mara Nord project has been to research the quality assurance of new asphalt pavement. Ground penetrating radar (GPR) survey is used as an alternative method for coring in quality assurance. There exist numerous advantages for the use of GPR. For example, the fluent measuring arrangements without closing the traffic on the road and the extensive continuous profile that can be constructed from the measuring data. Within the framework of Mara Nord Project field tests were organized in Seinäjoki region in Finland on August 2011. The tests were done by four consulting companies from Finland and Rovaniemi University of Applied Sciences. The aim of these tests was to compare the measured dielectric value profiles and the calculated void content profiles of the equipment. The tested equipment was GSSI manufactured SIR-20 and 1 GHz horn antennas. Void content values were calculated using the model presented by Mr. Roimela (1997). All core samples were taken from the right wheel path. The same reference core samples were used when analyzing the data of each GPR equipment. Some samples were taken right after the pavement work was completed with the rest three weeks after during the test measurements. The tests indicated that GPRs have very good repeatability in measuring dielectric changes on top surface layers of asphalt pavements. Furthermore, different GPRs locate the same detectable longitudinal dielectric changes with high accuracy. Some differences were found in the dielectric value levels, yet reproducibility of the calculated void content values was quite good. The test data was also used to evaluate the reliability of the regression model between the dielectric values measured through GPR and the void content of the pavement determined from reference cores. Test data indicated that accurate regression model could not be validated by using test data because of too wide variation. The variation of void content in core sample results was not always registered by GPR with corresponding variation in dielectric value. There was some moisture present in test conditions and this might have influenced the GPR results. There are some reference data from dry conditions which will be used later on for analyzing the influence of moisture. There was also quite wide variation in void content determined from core samples taken close to each other during field tests. However, wide variation was not seen in core samples taken right after the pavement work. It is possible that traffic load had its effect on the asphalt pavement compaction. The results indicate that when using only one survey line it should be located between wheel paths. Another option is GPR void content measurements should be done right after the pavement work.

Poikajärvi, J.; Peisa, K.; Narbro, A.

2012-04-01

133

Calculation method for permanent deformation of unbound pavement materials  

OpenAIRE

An analytical-mechanistic method for the calculation of permanent deformations of pavements has been developed at the Technical Research Centre of Finland (VTT) over some years by the author. The calculation method is needed in the analytical design procedure of pavements. This research concentrated on the calculation method for permanent deformations in unbound pavement materials. The calculation method was generated based on the results of full-scale accelerated pavement tests along with th...

Korkiala-tanttu, Leena

2009-01-01

134

Design of overlays based on pavement condition, roughness, and deflections  

Science.gov (United States)

The development and use of a pavement maintenance rating system and the development of two procedures for designing the thickness of overlays are summarized. It is demonstrated that objective rating systems can be used to prioritize pavements scheduled for resurfacing and that the procedures for overlay design based on the existing pavement structure and on traffic loadings are practical.

McGhee, K. H.

1982-01-01

135

Pavement Sealcoat, PAHs, and the Environment  

Science.gov (United States)

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.

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

2011-12-01

136

Finite Deformation Analysis of Layered Asphalt Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available Layered asphalt pavement structures are usually analyzed applying small deformation theory. In this study, finite deformation theory was employed to achieve more accurate results. The response of pavement structure under vertical and horizontal loads was investigated by three-dimensional finite element method. The calculating results, especially for deflection, on the basis of finite deformation theory are very different from that according to the small deformation theory. And the difference will increase while the stiffness of pavement structure decrease. With only vertical loads, asphalt layer is mainly under compressive stress in three directions. With horizontal loads and vertical loads, shear stress contributes to accumulated plastic deformation in the asphalt layer. Sliding between layers could occur due to the shear stress. Tensile strain can cause fatigue cracking in asphalt layer under low temperature. Due to a small modulus of resilience, there exists a large compressive strain and visible deflection in soil base.

Ming-Jian Li

2013-01-01

137

Distressed Couples and Marriage Education  

Science.gov (United States)

Professionals generally believe that couples who choose to attend marriage education programs are not as distressed as are clinical couples and that distressed couples are not good candidates for marriage education. We examined these assumptions in 129 married couples who enrolled in a PAIRS, Practical Application of Intimate Relationship Skills…

DeMaria, Rita M.

2005-01-01

138

Mechanistic - empirical pavement design guide implementation and pavement preservation strategies with asphalt rubber  

OpenAIRE

Asphalt-Rubber (AR) mixtures, with their great fleld performance, have received great attention from many transportation agencies world-wide. Current pavement design procedures do not specifically address the unique engineering properties that these mixtures offer. For example, the Mechanistic-Empirical Pavement Design Guide (MEPDG) did not include asphalt-rubber mixes as part of its calibration and Implementation in the USA. This paper addresses some issues on asphalt rubber mixture...

Kaloush, Kamil; Way, George B.; Belshe, Mark; Rodezno, Maria Carolina

2011-01-01

139

Distress or no distress, that's the question: A cutoff point for distress in a working population  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The objective of the present study is to establish an optimal cutoff point for distress measured with the corresponding scale of the 4DSQ, using the prediction of sickness absence as a criterion. The cutoff point should result in a measure that can be used as a credible selection instrument for sickness absence in occupational health practice and in future studies on distress and mental disorders. Methods Distress is measured using the Four Dimensional Symptom Questionnaire (4DSQ, a 50-item self-report questionnaire, in a working population with and without sickness absence due to distress. Sensitivity and specificity were compared for various potential cutoff points, and a receiver operating characteristics analysis was conducted. Results and conclusion A distress cutoff point of ?11 was defined. The choice was based on a challenging specificity and negative predictive value and indicates a distress level at which an employee is presumably at risk for subsequent sick leave on psychological grounds. The defined distress cutoff point is appropriate for use in occupational health practice and in studies of distress in working populations.

Schaufeli Wilmar B

2008-01-01

140

Permeable pavement research ? Edison, New Jersey  

Science.gov (United States)

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

141

Comparative study of nondestructive pavement testing, WES (Waterways Experiment Station) NDT (nondestructive tests) methodologies  

Science.gov (United States)

A demonstration of nondestructive airfield pavement evaluation procedures conducted by the US Army Engineer Waterways Experiment Station (WES) using both the WES 16-kip vibrator and a Dynatest falling weight deflectometer (FWD) is described. The nondestructive tests (NDT) were conducted at MacDill Air Force Base on five pavement test areas consisting of asphaltic concrete, portland cement concrete, and composite pavements. Two methods of data analysis were used. The dynamic stiffness modulus (DMS) method used dynamic deflection data from the WES 16-kip vibrator with a correlation analysis developed a number of years ago by WES. This method uses a correlation between the DSM (a load-deflection ratio) and the allowable load on a single wheel as derived from traditional test pit methods. The second analysis scheme used measured deflection basins at the pavement surface and layered elastic theory. Elastic moduli are computed by matching measured deflection basins with computed basins. Limiting stress/strain is then used to compute allowable aircraft loadings. This method was used with data from both the WES 16-kip vibrator and the FWD. Also demonstrated was a method of determining joint load transfer and of making appropriate adjustments to the allowable load to account for lack of load transfer.

Hall, J. W.; Alelxander, D. R.

1985-09-01

142

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2011-02-05

143

Over the Edge and Back: What to Do If You Drive Off the Pavement Edge  

Science.gov (United States)

... on similar roads. AAA Foundationfor Traffic Safety Pavement edge drop-off “ Pavement edge drop-off crashes are over twice as likely ... to do if you drive off the pavement edge • • IF THERE ARE NO OBSTACLES DIRECTLY IN FRONT ...

144

23 CFR 973.208 - Indian lands pavement management system (PMS).  

Science.gov (United States)

...208 Indian lands pavement management system (PMS). In addition...the AASHTO's “Pavement Management Guide.” 1 1 “Pavement Management Guide,” AASHTO...depend on mileage, functional classes, volumes, loading,...

2010-04-01

145

Application of CalME incremental-recursive method to the evaluation of the structural condition as asphalt pavements  

International Nuclear Information System (INIS)

CalME procedure represents one of the most advanced tools for the design, of flexible pavements world-wide. IT is an incremental-recursive method, which means that pavements service life must be divided into many time intervals where both structural integrity and environmental conditions can be regarded as constants. It also means that the damage calculated at the end of each interval must be considered as initial condition for the next one. The goal of this type of models is the prediction of the evolution of the different distress mechanisms. The advantages of incremental-recursive procedures versus classical analytical design are shown in this paper. Advantages are shown not only in terms of design, but also as a tool in order to support structural evaluation. In particular, the potential of asphalt fatigue model incorporated in CalME is presented. this model is initially calibrated in the laboratory, and it is then re-calibrated based on the actual performance observed from field deflection testing. The model provides a reliable prediction of the future evolution of the damage of the asphalt mixture. Fatigue model validation has been conducted based on the performance from several flexible sections evaluated in CEDEX full-scale pavements test track. (Author) 14 refs.

146

Analysis of Asphalt Pavement under Nonuniform Tire-pavement Contact Stress using Finite Element Method  

Directory of Open Access Journals (Sweden)

Full Text Available Tire-pavement contact stress is traditionally assumed to be uniformly distributed over a circular contact area. In this study, the tire-pavement contact pressure has been modeled to be nonuniform. A new tire model is developed for the analysis based on the geometry of the tire footprint because the contact area between the tire and the pavement is not exactly rectangular or circular. 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 and to model in-situ pavement performance. The creep parameters C1, C2 and C2 are developed from the triaxial repeated load creep test at 50C and at frequency of 1 Hz. Viscoplastic model (creep model is adopted and a commercially available Finite Element (FE program, ANSYS, is used in this study, in order to predict the rutting for in-situ pavement under nonuniform contact pressure. In the simulation, the used element has an eight-node with a three degrees of freedom per node translations in the nodal x, y and z directions. Dual wheel system of a standard axle load of 80 kN is used in the 2D pavement in-situ performance analysis. Reasonable agreement has been obtained between the predicted rut depths and the measured one. Moreover, it is found that creep model 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 tools to analyze rutting of asphalt pavements.

A.K. Ariffin

2011-01-01

147

Hypertension Awareness and Psychological Distress  

OpenAIRE

There is conflicting evidence regarding the association of hypertension with psychological distress, such as anxiety and depressive symptoms. The association may be because of a direct effect of the raised blood pressure, adverse effects of treatment, or the consequences of labeling. In a representative study of 33 105 adults (aged 51.7 +/- 12.1 years; 45.8% men), we measured levels of psychological distress using the 12-item General Health Questionnaire and collected blood pressure, data on ...

Hamer, M.; Batty, G. D.; Stamatakis, E.; Kivimaki, M.

2010-01-01

148

Financial Distress in Cancer Patients  

OpenAIRE

Novel diagnostic and therapeutic options offer hope to cancer patients with both localized and advanced disease. However, many of these treatments are often costly and even well-insured patients can face high out-of-pocket costs. Families may also be at risk of financial distress due to lost wages and other treatment-related expenses. Research is needed to measure and characterize financial distress in cancer patients and understand how it affects their quality of life. In addition, health ca...

Souza, Jonas A.; Wong, Yu-ning

2013-01-01

149

Comparison Between 2-D and 3-D Stiffness Matrix Model Simulation of Sasw Inversion for Pavement Structure  

Directory of Open Access Journals (Sweden)

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.

Sri Atmaja P. Rosidi

2007-01-01

150

An Airport Pavement Traffic Simulation Based on CPN  

OpenAIRE

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

Heng Hong-jun; Yang Jue

2014-01-01

151

Pervious Concrete: New Era For Rural Road Pavement  

OpenAIRE

Pervious concrete is a relatively new concept for rural road pavement, with increase into the problems in rural areas related to the low ground water level, agricultural problem. Pervious concrete has introduced in rural road as a road pavement material. Pervious concrete as a paving material has seen renewed interest due to its ability to allow waterto flow through itself to recharge groundwater level and minimize storm water runoff. This introduction topervious concrete pavements reviews it...

Darshan S Shah, Prof Jayeshkumar Pitroda Prof J. J. Bhavsar

2013-01-01

152

Performance of Recycled Asphalt Pavement as Coarse Aggregate in Concrete  

OpenAIRE

Recycled asphalt pavement (RAP) is the reclaimed and reprocessed pavement material containing asphalt and aggregate. Most RAP is recycled back into pavements, and as a result there is a general lack of data pertaining to the mechanical properties for RAP in other possible applications such as Portland cement concrete. In the present study, some mechanical properties of Portland cement concrete containing RAP as coarse aggregate were investigated in the laboratory. Six concrete mixes of widely...

Okafor, Fidelis O.

2010-01-01

153

Evaluation of Road Pavement Density Using Ground Penetrating Radar  

OpenAIRE

This study describes an analysis of Ground Penetrating Radar (GPR) measurements at frequency range of 1.7-2.6 GHz to get a relationship between attenuation and density for nine road pavements slabs with different densities. There are about four different frequencies had been tested. The method is simple, fast, non-destructive and accurate way to determine the density of road pavement. Density is a one of the important parameter in order to determine the compressive strength of road pavement f...

Rsa, Raja Abdullah; Shafri, H. Zulhaidi M.; Mardeni, R.; Sabira Khatun; Muniandy, R.

2009-01-01

154

Deflection criteria for concrete pavement structural design and evaluation  

Energy Technology Data Exchange (ETDEWEB)

This paper focuses on a mechanistic-empirical analysis procedure to develop the deflection criteria for concrete pavement structural design and rehabilitation alternatives. By calibrating of existing concrete pavement standard structures with FEM analysis, the allowable design deflection values are proposed according to traffic classification and critical load position. Next, the critical deflection criteria for concrete pavement rehabilitation are recommended, which are based on the concept of erosion damage analysis and the investigation of FWD deflections measured from in-service concrete pavements. 15 refs., 4 figs., 11 tabs.

Tang, B.; Maruyama, T.; Takahashi, O. [Nagoya Institute of Technology, Nagoya (Japan)

1998-05-20

155

Proceedings of the Continuously Reinforced Concrete Pavement workshop  

Science.gov (United States)

Design, construction, and maintenance procedures of continuously reinforced concrete pavements are dicussed. Maintenance procedures were emphasized. Polymer patching, under sealing, and flexible and rigid overlays were considered.

1980-06-01

156

Global Cooling: Policies to Cool the World and Offset Global Warming from CO2 Using Reflective Roofs and Pavements  

Energy Technology Data Exchange (ETDEWEB)

Increasing the solar reflectance of the urban surface reduce its solar heat gain, lowers its temperatures, and decreases its outflow of thermal infrared radiation into the atmosphere. This process of 'negative radiative forcing' can help counter the effects of global warming. In addition, cool roofs reduce cooling-energy use in air conditioned buildings and increase comfort in unconditioned buildings; and cool roofs and cool pavements mitigate summer urban heat islands, improving outdoor air quality and comfort. Installing cool roofs and cool pavements in cities worldwide is a compelling win-win-win activity that can be undertaken immediately, outside of international negotiations to cap CO{sub 2} emissions. We propose an international campaign to use solar reflective materials when roofs and pavements are built or resurfaced in temperate and tropical regions.

Akbari, Hashem; Levinson, Ronnen; Rosenfeld, Arthur; Elliot, Matthew

2009-08-28

157

Ultra thin reinforced concrete pavement: practical applications  

OpenAIRE

Over the last decade considerable research effort has led to the development of Ultra Thin Reinforced Concrete Pavements (UTRCP). The objective of this paper is to present practical refinements to the original concepts and theories. This paper will briefly discuss the development of UTRCP, and problems encountered during the implementation of UTRCP technology. Refinements were proposed and implemented in a number of projects. These projects are discussed and illustrated to demonstrate the use...

Brink, J. H.

2012-01-01

158

Platelet surface glycoproteins. Studies on resting and activated platelets and platelet membrane microparticles in normal subjects, and observations in patients during adult respiratory distress syndrome and cardiac surgery.  

OpenAIRE

The accurate definition of surface glycoprotein abnormalities in circulating platelets may provide better understanding of bleeding and thrombotic disorders. Platelet surface glycoproteins were measured on intact platelets in whole blood and platelet membrane microparticles were assayed in cell-free plasma using 125I-monoclonal antibodies. The glycoproteins (GP) studied were: GP Ib and GP IIb-IIIa, two of the major intrinsic plasma membrane glycoproteins; GMP-140, an alpha-granule membrane gl...

George, J. N.; Pickett, E. B.; Saucerman, S.; Mcever, R. P.; Kunicki, T. J.; Kieffer, N.; Newman, P. J.

1986-01-01

159

Desempeño de pavimentos estabilizado con asfalto espumado en una prueba de pavimentos a escala real y carga acelerada Performance of foamed bitumen pavements in accelerated testing facility  

Directory of Open Access Journals (Sweden)

Full Text Available Uno de los objetivos claves de la gestión de pavimentos es desarrollar e implementar una estrategia de construcción y mantenimiento rentables, con el fin de alcanzar niveles requeridos de servicio y desempeño. Una técnica rentable y sustentable para la rehabilitación de pavimentos es la de estabilización o reciclado con asfalto espumado (AE. Este artículo presenta un estudio sobre el desempeño de pavimentos estabilizados con asfalto espumado en el Canterbury Accelerated Pavement Testing Indoor Facility CAPTIF. CAPTIF es un laboratorio a escala real para pavimentos ubicado en Nueva Zelandia, que permite aplicar un gran número de cargas de tráfico en un breve período de tiempo. Seis secciones de pavimentos con distintos contenidos de asfalto y cemento fueron ensayadas en CAPTIF. Los resultados del experimento mostraron que las deflexiones disminuyen en las secciones con mayor contenido de asfalto espumado. Luego de aplicar más de un millón de ciclos de carga, las secciones estabilizadas sólo con cemento, s?lo con asfalto y la sección sin estabilizar mostraron un deterioro significativo en forma de ahuellamiento. Por otro lado, las secciones que fueron estabilizadas con AE y cemento mostraron un buen desempeño, demostrando que el cemento y el AE juntos mejoran significativamente el desempeño del pavimento. Los resultados de ahuellamiento fueron empleados para desarrollar modelos y describir el deterioro estable y acelerado de los pavimentos en estudio, lo que puede ser utilizado para una mejor gestión de los pavimentos estabilizados con asfalto espumado.One of the key principal goals of pavement asset management is to develop and implement cost-effective pavement construction and maintenance strategies that achieve the required levels of service and performance. A sustainable, cost-effective technique for rehabilitating pavements is foamed bitumen stabilization. This paper presents a study on the performance of foamed bitumen pavements tested in the Canterbury Accelerated Pavement Testing indoor Facility (CAPTiF, for full scale testing of pavements. Six pavement sections were tested; the variables were bitumen and cement content; one control section with the untreated unbound material was tested. Results showed that surface deflections decreased at sections with higher bitumen contents. After the application of 5,710,000 Equivalent Standard Axles (ESAs, the sections stabilised with cement only, bitumen only, and the control section all showed large amounts of rutting. Conversely, little rutting was observed in the three sections stabilised with foamed bitumen and 1.0% cement, showing that cement and FB together significantly improve pavement performance. The rutting results were used to develop models to describe the stable and unstable performance of the tested pavements. The paper concludes by outlining some of the practical benefits of utilising this technology in pavement asset management.

Alvaro Gonzalez

2012-08-01

160

Electro-optical approach to pavement deflection management  

Science.gov (United States)

A prototype continuous deflection device, referred to as a rolling weight deflectometer (RWD), has been developed as a nondestructive evaluation tool for airfield pavements. The system consists of a rigid trailer equipped with specially designed optical triangulation pavement sensors, a high-speed data acquisition system, and a high-pressure tire/load platform assembly. Pavement sensors are mounted on a rigid box beam equipped with an internal sensor system that corrects, in real time, the relative pavement height position measurements for displacements induced in the beam by mechanical vibrations, changes in temperature, or nonuniform dynamic loads at points where the beam attaches to the frame. The device produces continuous deflection profiles that show pavement response to a moving loaded wheel along the path of travel. These deflection profiles, combined with multiple passes along a lane, provide a far more detailed picture of the pavement structural integrity than has ever before been possible, because existing evaluation tools only produce response information at discrete points. Preliminary results show deflections measured by the RWD are in general agreement with the expected pavement response for various loads. A discussion of the device configuration, preliminary data, and potential as a pavement management tool is presented.

Rish, Jeff W., III; Adcock, Avery D.; Tuan, Christopher Y.; Baker, Samuel L.; Welker, Hugh W., II; Johnson, Roger F.

1995-07-01

161

Research on pavement crack recognition methods based on image processing  

Science.gov (United States)

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.

Cai, Yingchun; Zhang, Yamin

2011-06-01

162

Permeable Pavement Demonstration at the Edison Environmental Center (Hartford)  

Science.gov (United States)

In general, there is a lack of full-scale, outdoor, real-world porous pavement studies with system replicates. More studies of porous pavement operating in its intended use (parking lot, roadway, etc.) with climatic events, regular use, and maintenance effects, are necessary. The...

163

Permeable pavement demonstration at the Edison Environmental Center (Hartford, CT)  

Science.gov (United States)

In general, there is a lack of full-scale, outdoor, real-world porous pavement studies with system replicates. More studies of porous pavement operating in its intended use (parking lot, roadway, etc.) with climatic events, regular use, and maintenance effects, are necessary. The...

164

Permeable pavement demonstration site at Edison Environmental Center (Presentation)  

Science.gov (United States)

There are few studies of full-scale, outdoor, replicated, working pervious pavement systems. More studies of pervious pavement operating in its intended use (parking lot, roadway, etc.) during a range of climatic events, daily usage conditions, and maintenance regimes are necessa...

165

Permeable Pavement Research at the Edison Environmental Center  

Science.gov (United States)

There are few detailed studies of full-scale, replicated, actively-used permeable pavement systems. Practitioners need additional studies of permeable pavement systems in its intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage conditio...

166

Permeable pavement demonstration at the Edison Environmental Center  

Science.gov (United States)

There are few studies of full-scale, outdoor, replicated, functioning pervious pavement systems. More studies of pervious pavement operating in its intended use (parking lot, roadway, etc.) during a range of climatic events, daily usage conditions, and maintenance regimes are nec...

167

Permeable Pavement Monitoring at the Edison Environmental Center Demonstration Site  

Science.gov (United States)

There are few detailed studies of full-scale, replicated, actively-used pervious pavement systems. Practitioners need additional studies of pervious pavement systems in its intended application (parking lot, roadway, etc.) during a range of climatic events, daily usage conditions...

168

Measurements of the Stiffness and Thickness of the Pavement Asphalt Layer Using the Enhanced Resonance Search Method  

Science.gov (United States)

Enhanced resonance search (ERS) is a nondestructive testing method that has been created to evaluate the quality of a pavement by means of a special instrument called the pavement integrity scanner (PiScanner). This technique can be used to assess the thickness of the road pavement structure and the profile of shear wave velocity by using the principle of surface wave and body wave propagation. In this study, the ERS technique was used to determine the actual thickness of the asphaltic pavement surface layer, while the shear wave velocities obtained were used to determine its dynamic elastic modulus. A total of fifteen locations were identified and the results were then compared with the specifications of the Malaysian PWD, MDD UKM, and IKRAM. It was found that the value of the elastic modulus of materials is between 3929?MPa and 17726?MPa. A comparison of the average thickness of the samples with the design thickness of MDD UKM showed a difference of 20 to 60%. Thickness of the asphalt surface layer followed the specifications of Malaysian PWD and MDD UKM, while some of the values of stiffness obtained are higher than the standard. PMID:25276854

Zakaria, Nur Mustakiza; Yusoff, Nur Izzi Md.; Hardwiyono, Sentot; Mohd Nayan, Khairul Anuar

2014-01-01

169

Pervious Concrete: New Era For Rural Road Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available Pervious concrete is a relatively new concept for rural road pavement, with increase into the problems in rural areas related to the low ground water level, agricultural problem. Pervious concrete has introduced in rural road as a road pavement material. Pervious concrete as a paving material has seen renewed interest due to its ability to allow waterto flow through itself to recharge groundwater level and minimize storm water runoff. This introduction topervious concrete pavements reviews its applications and engineering properties, including environmentalbenefits, structural properties, and durability.In rural area cost consideration is the primary factor which must be kept in mind. So that in rural areas costly storm water management practices is not applicable. Pervious concrete pavement is unique and effective means to meet growing environmental demands. By capturing rainwater and allowing it to seep into the ground. This pavement technology createsmore efficient land use by eliminating the need for retention ponds, swell, and other costly stormwater management devices.

Darshan S. Shah 1 , Prof. Jayeshkumar Pitroda2Prof.J.J.Bhavsar

2013-08-01

170

Adjustment to Cancer: Anxiety and Distress (PDQ)  

Science.gov (United States)

... manage a stressful event such as a cancer diagnosis. In normal adjustment, a person learns to cope well with emotional distress and solve problems related to cancer. Psychological and social distress—A condition in which a ...

171

Characterization of nanoparticles released during construction of photocatalytic pavements using engineered nanoparticles  

International Nuclear Information System (INIS)

With the increasing use of titanium dioxide (TiO2) nanoparticles in self-cleaning materials such as photocatalytic concrete pavements, the release of nanoparticles into the environment is inevitable. Nanoparticle concentration, particle size, surface area, elemental composition, and surface morphology are pertinent to determine the associated risks. In this study, the potential of exposure to synthetic nanoparticles released during construction activities for application of photocatalytic pavements was measured during laboratory-simulated construction activities of photocatalytic mortar overlays and in an actual field application of photocatalytic spray coat. A scanning mobility particle sizer system measured the size distribution of nanoparticles released during laboratory and field activities. Since incidental nanoparticles are released during construction activities, nanoparticle emissions were compared to those from similar activities without nano-TiO2. Nanoparticle counts and size distribution suggest that synthetic nanoparticles are released during application of photocatalytic pavements. In order to identify the nanoparticle source, nanoparticles were also collected for offline characterization using transmission electron microscopy. However, positive identification of synthetic nanoparticles was not possible due to difficulties in obtaining high-resolution images. As a result, further research is recommended to identify nanoparticle comporecommended to identify nanoparticle composition and sources.

172

Financial Distress Comparison Across Three Global Regions  

OpenAIRE

Globalization has precipitated movement of output and employment between regions. We examine factors related to corporate financial distress across three continents. Using a multidimensional definition of financial distress we test three hypotheses to explain financial distress using historical financial data. A null hypothesis of a single global model was rejected in favor of a fully relaxed model which created individual financial distress models for each region. This result suggests that d...

Platt, Harlan D.; Platt, Marjorie B.

2008-01-01

173

Psychological Distress among Young Norwegian Health Professionals  

OpenAIRE

High psychological distress has been shown to be a risk for acquisition of skills that are necessary when working in the health professions. In this study, we present longitudinal data on psychological distress among 169 young Norwegian health professionals. We measured distress at the end of their studies, and three years later on, when being professional nurses, physiotherapists and occupational therapists. Psychological distress was assessed by applying the 12-item version of the General H...

Per Nerdrum; Amy Østertun Geirdal

2013-01-01

174

PERCEPTION OF DISTRESS BY OBSESSIVE COMPULSIVE PATIENTS  

OpenAIRE

A life event inventory has been used to compare forty obsessive compulsive neurosis patients with equal number of non-psychiatric normal controls which were matched in terms of age, sex and, economic status. Ratings by the obsessionals of the degree of happiness or distress produced by their life experiences revealed that obsessionals have significantly greater mean distress rating i.e., higher mean distress score and significantly more mean numbers of distressing events than non-psychiatric ...

Lal, Narottam; Agarwal, Ashok K.; Sinha, P. K.

1986-01-01

175

New structural systems for zero-maintenance pavements. Volume 1: Analytical and experimental studies of an anchored pavement. A candidate zero-maintenance pavement  

Science.gov (United States)

The design feasibility and construction cost effectiveness of an anchored pavement concept for zero maintenance highways are investigated. An analytical model is designed to verify computer program results and to investigate construction methods for a full-scale highway section. A conventional slab and an anchored pavement in both continuous and jointed configurations were subjected to heat transfer, thermal stress, and mechanical stress analyses. The anchored pavement offers two distinct advantages over a conventional pavement. Deflections are lower and more uniform; and stresses in the soil are lower and distributed more widely by the rigid anchors. Three dimensional finite element analysis is considered to be the most efficient technique for examining the significance of environmentally induced stress.

Saxena, S. K.; Rosenkranz, W. J.; Militsopoulos, S. G.

1980-05-01

176

Permeable Pavement Research ? Edison, NJ  

Science.gov (United States)

This presentation gives the rationale behind NRMRL?s decision to construct and test a permeable surface parking lot the Edison Environmental Center. It also describes the monitoring program and gives preliminary results. The presentation is being given at the request of the New...

177

Perfectionism, Procrastination, and Psychological Distress  

Science.gov (United States)

Using a cross-panel design and data from 2 successive cohorts of college students ( N = 357), we examined the stability of maladaptive perfectionism, procrastination, and psychological distress across 3 time points within a college semester. Each construct was substantially stable over time, with procrastination being especially stable. We also…

Rice, Kenneth G.; Richardson, Clarissa M. E.; Clark, Dustin

2012-01-01

178

Variability of pavement noise benefit by vehicle type  

Science.gov (United States)

The Volpe Center Acoustics Facility, in support of the California Department of Transportation (Caltrans), is participating in a long-term study to assess several types of pavement for the purpose of noise abatement. On a four-mile stretch of a two-lane highway in Southern California, several asphalt pavement overlays are being examined. Acoustical, meteorological, and traffic data are collected in each pavement overlay section, where microphones are deployed at multiple distances and heights. Single vehicle pass-by events are recorded primarily for three vehicle types: automobiles, medium trucks, and heavy trucks. Data are analyzed to determine the noise benefit of each pavement as compared to the reference dense-graded asphaltic concrete (DGAC); this includes a modified Statistical Pass-By Index as well as average Lmax values for each vehicle type. In addition, 1/3-octave band data are examined. Automobiles and heavy trucks are the focus of this paper, where benefits due to pavement will be presented for three pavement types: open-graded asphaltic concrete (OGAC) of 75 mm thickness, open-graded asphaltic concrete (OGAC) of 30 mm thickness, and rubberized asphaltic concrete, Type O (open) (RAC) of 30 mm thickness. Average Lmax values and spectral data show that noise benefits due to pavement can vary by vehicle type.

Rochat, Judith L.; Read, David R.

2005-09-01

179

An Innovative Strategy for Maintenance of Highway Pavement  

Directory of Open Access Journals (Sweden)

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.

Sandeep Choudhary, Dr. P. K. Agarwal

2013-05-01

180

Determination of Pavement Elevations by the 3D Scanning System and Its Verification  

Directory of Open Access Journals (Sweden)

Full Text Available It is necessary to be careful of geometric accuracy of the roadways when constructing them.Correct thickness of the individual construction layers together with roughness of thepavement belongs among important influences ensuring lifetime of the roadways andvehicles and for comfortable and safe car ride. It is necessary beside other things to havea reliable check measurement method at disposal so as to ensure the required accuracy ofthe individual construction layers will be achieved. The check measurement method mustbe able to measure a checked construction component with the required accuracy and withsufficiently high density describing not only global deviations, but also local deviations.The highest requirements on accuracy are placed on the final construction layer of theroadway. Layer thickness and pavement roughness are being evaluated here. The 3Dterrestrial scanning method is currently offered for geometric checking of its realization.The article deals with testing of procedure of the pavement roughness measurement withthe 3D terrestrial scanning system and with its verification by a total station measurement.Emphasis is put on verification of accuracy of absolute heights of points in the 3D modelof the pavement and on size of random errors in the elevation component. Results of thetesting clarified using the 3D terrestrial scanning systems and their accuracy for check ofthe roadway surface.

Tomáš K?emen

2014-06-01

181

Full-scale accelerated pavement testing of Texas Mobile Load Simulator  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the test results from full-scale accelerated pavement testing with the Texas Mobile Load Simulator. Data from in-situ instrumentation and nondestructive testing were collected and analyzed at different loading stages to assess material property changes under accelerated loading. Forensic studies were made to study material characteristics in the longitudinal and transverse directions. It was found that at the early stage of trafficking the test pad responded to falling weight deflectometer (FWD) load linearly, not only over the whole pavement system but also within individual layers. Before mobile load simulator testing, FWD data indicated the weakest area exists at the left wheel path (LWP) of 7.5-m line (7.5L). Later, this weak area was confirmed to have the highest rutting and the most intensive cracking. The dynamic cone penetration results showed that the base at this location was at its weakest. Also, at 7.5L the dry density was lowest, {approximately}7% lower with a moisture content {approximately}8% higher than the adjacent area. The LWP had higher FWD deflections than the right wheel path (RWP), and consequently the LWP manifested more rutting. This proved to be primarily due to differences in moisture content. This was probably because more water infiltrated in the area during rain due to manifestation of more extensive cracking during early phases of trafficking. The maximum surface deflection values increased as trafficking increased in the left and right wheel paths due to pavement deterioration, while deflection for the center remained constant because of the lack of traffic loading. The LWP had more rutting than the RWP and this correlated with the measured FWL deflections prior to trafficking. The WI values increased as trafficking increased for the LWP and RWP due to pavement deterioration. The majority (>60%) of rutting was from the 300-mm uncrushed river gravel base.

Chen, D.H. [Texas Dept. of Transportation, Austin, TX (United States); Hugo, F. [Univ. of Texas, Austin, TX (United States). Center for Transportation Research

1998-09-01

182

Climate change, energy, sustainability and pavements  

International Nuclear Information System (INIS)

Provides an integrated perspective on understanding the impacts of climate change, energy and sustainable development on transportation infrastructure systems. Presents recent technological innovations and emerging concepts in the field of green and sustainable transportation infrastructure systems with a special focus on highway and airport pavements. Written by leading experts in the field. Climate change, energy production and consumption, and the need to improve the sustainability of all aspects of human activity are key inter-related issues for which solutions must be found and implemented quickly and efficiently. To be successfully implemented, solutions must recognize the rapidly changing socio-techno-political environment and multi-dimensional constraints presented by today's interconnected world. As part of this global effort, considerations of climate change impacts, energy demands, and incorporation of sustainability concepts have increasing importance in the design, construction, and maintenance of highway and airport pavement systems. To prepare the human capacity to develop and implement these solutions, many educators, policy-makers and practitioners have stressed the paramount importance of formally incorporating sustainability concepts in the civil engineering curriculum to educate and train future civil engineers well-equipped to address our current and future sustainability challenges. This book will prove a valuable resource in the hands of researchers, educators and future engineering leaders, most of whom will be working in multidisciplinary environments to address a host of next-generation sustainable transportation infrastructure challenges.

183

Climate change, energy, sustainability and pavements  

Energy Technology Data Exchange (ETDEWEB)

Provides an integrated perspective on understanding the impacts of climate change, energy and sustainable development on transportation infrastructure systems. Presents recent technological innovations and emerging concepts in the field of green and sustainable transportation infrastructure systems with a special focus on highway and airport pavements. Written by leading experts in the field. Climate change, energy production and consumption, and the need to improve the sustainability of all aspects of human activity are key inter-related issues for which solutions must be found and implemented quickly and efficiently. To be successfully implemented, solutions must recognize the rapidly changing socio-techno-political environment and multi-dimensional constraints presented by today's interconnected world. As part of this global effort, considerations of climate change impacts, energy demands, and incorporation of sustainability concepts have increasing importance in the design, construction, and maintenance of highway and airport pavement systems. To prepare the human capacity to develop and implement these solutions, many educators, policy-makers and practitioners have stressed the paramount importance of formally incorporating sustainability concepts in the civil engineering curriculum to educate and train future civil engineers well-equipped to address our current and future sustainability challenges. This book will prove a valuable resource in the hands of researchers, educators and future engineering leaders, most of whom will be working in multidisciplinary environments to address a host of next-generation sustainable transportation infrastructure challenges.

Gopalakrishnan, Kasthurirangan [Iowa State Univ., Ames, IA (United States). Dept. of Civil, Construction and Environmental Engineering; Steyn, Wynand JvdM [Pretoria Univ. (South Africa). Dept. of Civil Engineering; Harvey, John (ed.) [California Univ., Davis, CA (United States). Dept. of Civil and Environmental Engineering

2014-07-01

184

Development of Improved Mechanistic Deterioration Models for Flexible Pavements  

DEFF Research Database (Denmark)

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 to be done to be succesful in establishing mechanistic models based on Accelerated Load Testing (ALT) complemented by laboratory testing.

Ullidtz, Per; Ertman, Hans Larsen

1998-01-01

185

Time series observations of marsh recovery and pavement persistence at three Metula spill sites after 30.5 years  

International Nuclear Information System (INIS)

In 1974, the oil tanker Metula ran aground in the Strait of Magellan, Chile and spilled about 50,000 tons of light Arabian crude and 2,000 tons of Bunker C fuel. No attempt was made to recover or treat the stranded oil and the coast was left to recover by natural attenuation. Field visits to the coastal sites affected by the spill were conducted 30 years after the incident. The survey in 2005 repeated observations and measurements made in 1998 in the heavily affected Punta Espora area that documented salt marsh recovery at 2 sites, and changes in asphalt pavement at a third site. The 1998 survey also indicated that tilling was responsible for a significant increase in the number of plants that recolonized the area. A comparison of the plant counts between 1998 and 2005 showed that the number of plants in tilled plots was reduced because of fewer larger plants. A comparison of oil distribution in the west marsh from 1998 to 2005 showed that recolonization was evident. A large 550 m-long asphalt pavement on a mixed sediment beach showed very little changes in pavement area in the aftermath of the spill. However, the upper edge of the pavement showed signs of erosion by backwash action of waves during high-tide. The presence of surface oil cover continues to dominate the physical character of the upper intertidal and supratidal zones. 11 refs., 6 tabs., 3 figs

186

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

DEFF Research Database (Denmark)

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 Performance Study, is to develop an improved mechanistic subgrade failure criterion.Simulated traffic loads were applied between June and December 1997 by a dual tyre loading cart within a climate chamber maintained at a constant temperature. Three load levels (40 kN, 50 kN and 60 kN) were applied. In all three test series, 50000 load repetitions were applied at each load level, and the test chamber temperature was maintained at approximately 25 degree C.Instruments installed in the test pavement included: Strain measuring sensors (LVDT Soil Strain Deformation Transducers and Asphalt Strain Gauges), Soil Pressure Cells, Thermistors and Pore Pressure Sensors. Routine monitoring of instrument responses and surface profiles with a Profilometer and FWD/LWD structural testing were undertaken at regular intervals during the construction and load testing programmes.This paper compares various structural analysis 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.

Baltzer, S.; Zhang, W.

1998-01-01

187

Automatic Detection and Classification of Defect on road Pavement using Anisotropy Measure  

OpenAIRE

Automatic pavement cracking detection is a part of road maintenance and rehabilitation strategies. Cracks detec-tion is one of the main features used by road authorities to manage efficiently its networks. Road surface is made using aggregates which can have different sizes, organized randomly. Scanned pictures of theses surfaces appear has random distribution of a re-duced set of gray levels. Cracks or defaults can't be ex-tracted by a simple threshold. In this paper, we introduce a measure ...

Nguyen, Tien Sy; Avila, Manuel; Begot, Ste?phane

2009-01-01

188

On-site inspections of pavement damages evolution using GPR  

Science.gov (United States)

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 approximately 160 km/day at 40 km/h speed, on the average. After processing and first-checking, GPR profiles were divided into homogeneous sections according to the combination of different parameters (e.g. route analyzed, long distance conditions of regularity/irregularity in layers arrangement). In such context, a high consistency between surface damages, mismatches from the GPR scans, and boundary environmental conditions was demonstrated. In addition, deep mismatches were detected even for early-stage or unrevealed faults. The second set of surveys was carried out in autumn in high humidity conditions, due to recent rainfalls. 160 km of relevant routes from the same road network were investigated. Results showed a high consistency with those collected during the first-stage of surveys. Minor changes were found in those sections with low traffic loads (e.g. farther away from the biggest town of Rieti), whereas major mismatches were detected in wetlands (e.g. close to rivers), work zones, and nearby those sections already deeply damaged in the past. This work benefited from networking activities carried out within the EU funded COST Action TU1208 'Civil Engineering Applications of Ground Penetrating Radar'.

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

2014-05-01

189

Unconventional Banking System in Distress  

OpenAIRE

AbstractWith the proliferation of banking sector problems around the world, in the last few years the empirical literature on systemic banking crises has grown significantly. This literature has frequently focused attention on the factors connected with the onset of conventional banking distress, in order to identify the determinants of the crises or to look for “early warning indicators” of difficulty. In fact a number of studies have relied on factors determining bank failures related t...

Wassim Rajhi; Slim Ahmed Hassairi

2011-01-01

190

The impact of light-colored pavements on active layer dynamics revealed by Ground-Penetrating Radar monitoring  

DEFF Research Database (Denmark)

Ground-penetrating radar (GPR) has been used to study the variations in the depth of the frost table throughout a complete thaw-freeze season in Kangerlussuaq Airport, western Greenland. In autumn 2000, three test areas were painted white on the parking area of the airport in order to reduce further development of depressions in the asphalt pavement. One of these areas has been used in the GPR investigations to compare the variations of the frost table underneath a normal dark asphalt surface to that below a more reflective surface. The GPR results have shown a clear correlation between the use of the reflective surface and a reduced depth to frost table. In late summer the difference in the depths to the frost table is approximately 0.9 m. The results should promote the interest in the development and use of light colored pavement materials in order to reduce the effect of a warming climate on arctic infrastructures.

JØrgensen, Anders Stuhr; Ingeman-Nielsen, Thomas

2008-01-01

191

Laboratory analysis of the infiltration capacity of interlocking concrete block pavements in car parks.  

Science.gov (United States)

Interlocking concrete block pavements (ICBPs) have been widely used in car parks to reduce runoff. Researches have demonstrated that clogging is the most influential factor in the reduction of the infiltration capacity of this type of permeable pavement. Nevertheless, there is no laboratory study of the infiltration performance of ICBPs that combines clogging levels with variables related with the topography of car parks such as runoff surface length (R(SL)) and surface slope (S(S)). This paper studies the infiltration behaviour of ICBP during their operational life in a car park using an improved version of the Cantabrian Fixed (CF) Infiltrometer. This laboratory device simulates direct rainfall and runoff from adjacent impervious areas over an ICBPs surface of 0.25 m(2) for different slopes (0, 3, 5, 7 and 10%) and three scenarios of clogging (surface newly built, surface clogged and surface clogged with maintenance). This paper presents the results of the tests and a statistical analysis based on three regression models (corresponding to each clogging scenario) depending on the R(SL) and S(S) variables. All models passed a confidence level of 95%, presenting high R(2) values and showing that R(SL) is a more influential variable than the S(S) for all clogging scenarios. PMID:23202575

Sañudo-Fontaneda, Luis A; Rodriguez-Hernandez, Jorge; Vega-Zamanillo, Angel; Castro-Fresno, Daniel

2013-01-01

192

Data Analysis Report : Preliminary Test Pavement Danish Road Testing Machine  

DEFF Research Database (Denmark)

Main conclusions: 1) The Asphalt Strain Gauges (ASG), the Soil Deformation Transducers (SDT) and the Soil Pressure Cells (SPC) performed well during the experiment, but the SPCs need frequent in situ calibration. A different installation procedure for the SPCs should be considered. Due to the variability of the soil more instruments (than two) are needed for each response value to be determined. 2) Strains measured using the emu coils did not have a satisfactory degree of accuracy. Laboratory tests showed the Kulite pressure cells to be dependent upon loading history and soil stiffness. For this reason the cells were not used in the RTM experiment. The volumetric moisture content recorded by the VITEL moisture probes did not appear to be reliable. 3) Linear elastic theory did not give a satisfactory agreement with measured stresses and strains. The measured vertical strains could be several times larger than the theoretical values. Elsym5 seems to produce incorrect deflections in some cases. 4) Satisfactory agreement between measured and theoretical stresses and strains could be obtained using the Finite Element Method and appropriate non-linear relationships for the moduli of the unbound materials. 5) The variation of stresses and strains with distance from the load was found to be in very good agreement with Boussinesgs equations, with the exception of the horizontal stress. The relationship between the depth used with Boussinesq's equations the the actual depth needs further study. 6) The subgrade showed thixotropyc behavior with strains increasing with the number of load repetitions and decreasing after a rest period. This behavior was only observed under the wheel load, not under the FWD. 7) Existing design criteria for subgrades appear to be reasonable when used with strains calculated using linear elastic theory and moduli determined from FWD tests, but ar much too conservative if used with measured strains. 8) Plastic strain in the subgrade, surface rutting and roughness could all be related to the measured resilient strain at the top of the subgrade, with damage being proportional to the load raised to a power between 6.23 and 6.67. These relationships can be used to calculate the pavement condition after a given number of loads or to determine the permissible number of loads for a given terminal condition of the pavement. For surface rutting and roughness the contribution from the individual layers could not be established.

Ullidtz, Per; Zhang, Wei

1997-01-01

193

A Detailed Study of Cbr Method for Flexible Pavement Design  

OpenAIRE

As per IRC recommendation, California Bearing Ratio (CBR) value of subgrade is used for design of flexible pavements. California Bearing Ratio (CBR) value is an important soil parameter for design of flexible pavements and runway of air fields. It can also be used for determination of sub grade reaction of soil by using correlation. It is one of the most important engineering properties of soil for design of sub grade of roads. CBR value of soil may depends on many factors lik...

Er. Devendra Kumar Choudhary; Joshi, Dr Y. P.

2014-01-01

194

Optical fiber feasibility study in Accelerated Pavement Testing facility  

OpenAIRE

The presented research has been carried out within the European project Intelligent Roads (INTRO). The major objective followed was to assess the potential of optical fiber for pavement monitoring in comparison with classical strain gauges. Thus, both measurement devices have been tested under the same conditions in a full scale Accelerated Pavement Testing (APT) at LAVOC. This facility allows the user to control different parameters such as loading configuration and temperature and, as a mat...

Bueche, N.; Rychen, P.; Dumont, A. -g; Santagata, E.

2009-01-01

195

Constructibility aspects of ultra thin continuously reinforced concrete pavement  

OpenAIRE

Ultra Thin Continuously Reinforced Concrete Pavement (UTCRCP) is a new rehabilitation technique for roads which was originally imported from overseas and redesigned for South Africa conditions. Initial development involved accelerated pavement testing (APT) with the Heavy Vehicle Simulator (HVS) on experimental sections at the Heidelberg Traffic Control Centre. The success of these short experimental sections shifted the emphasis to constructability issues and associated design issues on a la...

Mukandila, M. W. K. E.; Milne, T. I.; Horak, Emile

2009-01-01

196

A binder for quick repair of pavements  

Energy Technology Data Exchange (ETDEWEB)

A binder compound is patented which is based on bitumen for quick repair of road pavements (Pk), which contains, in percent: oxidized bitumen with a softening point based on KiSh at 70 to 130 degrees of 30 to 60, a hydrocarbon diluent (lacquer benzine, aromatic hydrocarbons (ArU) with a boiling point in a range of 100 to 220 degrees) and their mixture with benzine, 35 to 69.95 and 0.05 to 5 percent of an adhesion additive. The additive may be anion active (for instance, fatty acids, their ethers and residues from distillation of fatty acids) or the cation active type (for instance, alkylamines, acylaminoamides, substituted imidazoline and N-alkylpolypropylenpolyamines).

Buchta, J.; Benes, V.; Chaloupka, J.; Krejci, J.; Kubanek, L.; Sterba, J.

1982-01-01

197

Governance in financial distress and bankruptcy  

OpenAIRE

This chapter provides a survey of law, economics, and finance scholarship at the intersection of corporate governance and financial distress. In financial distress, both inside and outside of bankruptcy court, formal and informal control rights are paramount. Thus, we organize our review around the major constituencies that exercise control rights in distressed firms: shareholders, managers and boards; senior and junior creditors; and the law, courts and judges. Broadly, our review suggests t...

Thorburn, Karin S.; Ayotte, Kenneth M.; Hotchkiss, Edith S.

2013-01-01

198

Preemptive distress resolution through bank mergers  

OpenAIRE

This paper suggests a motive for bank mergers that goes beyond alleged and typically unverifiable scale economies: preemtive resolution of banks´ financial distress. Such "distress mergers" can be a significant motivation for mergers because they can foster reorganizations, realize diversification gains, and avoid public attention. However, since none of these potential benefits comes without a cost, the overall assessment of distress mergers is unclear. We conduct an empirical analysis to p...

Elsas, Ralf

2004-01-01

199

A "wreckers theory" of financial distress  

OpenAIRE

In recent years, a number of papers have established a new empirical regularity. Stocks of distressed firms vastly underperform those of financially healthy firms. It is not necessary to attribute the negative excess returns of distressed firms to inefficient or irrational markets. We show that negative excess returns are the equilibrium outcome when a subset of participants is able to draw returns "in kind" from distressed companies. For firms close to bankruptcy, non-cash returns to ownersh...

Von Kalckreuth, Ulf

2005-01-01

200

DISTRESS AND JOB PERFORMANCE OF INDUSTRIAL WORKERS  

OpenAIRE

The present study aims at the investigation of the relationship between distress and job performance of industrial workers. The sample consisted of 500 workers of public and private sectors. CMI Health Questionnaire and Performance Appraisal Scale (PAS) were used to measure the level of distress and quality of performance at job, respectively. Results showed that physical, menial and overall distress correlated significantly and negatively with workers ?performance as appraised Furthermore,...

Samanta, C. R.; Singh, Avneesh

1993-01-01

201

Adjustment to Cancer: Anxiety and Distress (PDQ®)  

Science.gov (United States)

Expert-reviewed information summary about the difficult emotional responses many cancer patients experience. This summary focuses on normal adjustment issues, psychosocial distress, and adjustment disorders.

202

Differences between experienced and anticipatory distress.  

Science.gov (United States)

Differences between distress ratings of anticipated and experienced life events were examined (N = 168). Results showed significant differences between perceived and experienced aversion across events predicting symptoms of stress, depression, anxiety, and somatic discomfort in occupational, social, and familial situations. Gender differences were also found. Women reported significantly greater ratings of distress than men. Results reinforce the use of experienced events in overall distress assessment for individual clients, bring to question the existence of anticipated or perceived stress, and suggest that gender differences should be accounted for in the interpretation of distress measures. PMID:3760199

Sowa, C J; Barsanti, A N

1986-09-01

203

The acute respiratory distress syndrome.  

Science.gov (United States)

The acute respiratory distress syndrome (ARDS) is a major cause of acute respiratory failure. Its development leads to high rates of mortality, as well as short- and long-term complications, such as physical and cognitive impairment. Therefore, early recognition of this syndrome and application of demonstrated therapeutic interventions are essential to change the natural course of this devastating entity. In this review article, we describe updated concepts in ARDS. Specifically, we discuss the new definition of ARDS, its risk factors and pathophysiology, and current evidence regarding ventilation management, adjunctive therapies, and intervention required in refractory hypoxemia. PMID:25829644

Modrykamien, Ariel M; Gupta, Pooja

2015-04-01

204

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

Science.gov (United States)

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

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

2014-01-01

205

Analysis of Instrumentation Selection and Placement to Monitor the Hydrologic Performance of Permeable Pavement Systems and Bioinfiltration Areas at the Edison Environmental Center in New Jersey  

Science.gov (United States)

In 2009, the U.S. Environmental Protection Agency constructed a 0.4-ha (1-ac) parking lot surfaced with three different permeable pavement types (interlocking concrete pavers, porous concrete, and porous asphalt) and six bioinfiltration areas with three different drainage area to...

206

46 CFR 25.25-19 - Visual distress signals.  

Science.gov (United States)

...2010-10-01 2010-10-01 false Visual distress signals. 25.25-19 ...Lifesaving Equipment § 25.25-19 Visual distress signals. Each uninspected passenger vessel must meet the visual distress signal requirements of...

2010-10-01

207

46 CFR 169.553 - Pyrotechnic distress signals.  

Science.gov (United States)

...2010-10-01 2010-10-01 false Pyrotechnic distress signals. 169.553 Section...Additional Lifesaving Equipment § 169.553 Pyrotechnic distress signals. (a) All pyrotechnic distress signals must be of an...

2010-10-01

208

Design of Rigid and Flexible Pavements by Various Methods & Their Cost Analysis of Each Method  

OpenAIRE

Highway and pavement design plays an important role in the DPR projects. The satisfactory performance of the pavement will result in higher savings in terms of vehicle operating costs and travel time, which has a bearing on the overall economic feasibility of the project. This paper discusses about the design methods that are traditionally being followed and examines the “Design of rigid and flexible pavements by various methods & their cost analysis by each method”. Flexible pavement are...

Saurabh Jain

2013-01-01

209

Comparison of isotropic and cross-anisotropic analysis of pavement structures  

OpenAIRE

In most existing pavement design methods, pavements are analyzed using linear elastic multilayer theory, with the assumption that isotropic conditions are present in the structural layers of the pavement section. There are however numerous researchers that disagree with this assumption and their research have proven that there are inherent and induced cross-anisotropic material behaviors in the structural layers of a pavement section. The problem facing the South African Mechanistic Design Me...

Steyn, Wynand J. Vdm; Maina, James; Repsold, Anton

2013-01-01

210

Stormwater quality performance of a macro-pervious pavement car park installation equipped with channel drain based oil and silt retention devices.  

Science.gov (United States)

This paper reports the results of a two year field monitoring exercise intended to investigate the pollution abatement capabilities of a novel system which offers an alternative to the, now well established, pervious pavement system as a source control device for stormwater management. The aim of this study was to determine the effectiveness of a live installation of a macro-pervious pavement system (MPPS) (operated as a visitors' car park at a prison in Central Scotland) in retaining and treating a range of pollutants which originate from automobile use or become concentrated on the parking surface from the wider environment. The MPPS is a sub-class of pervious pavement system where the vast majority of the surface is impermeable. It directs stormwater into a pervious sub surface storage/attenuation zone through a series of distinct infiltration points fast enough to prevent flooding during the design storm. In the particular system studied here the infiltration points consist of a network of oil/silt separation devices with extensive further pollutant retention/degradation provided during the passage of stormwater through the sub surface zone. Approximately 12 months after the car park was completed a sampling regime was instigated in which grab samples were collected at intervals from each of the three sub catchments whilst, simultaneously, samples were collected directly from the, pollutant retaining, infiltration devices. Through investigation of samples collected at the upstream end of the system, the retention of significant amounts of hydrocarbons and heavy metals in the initial collection devices has been illustrated and the analysis of effluent samples collected at the outlet points indicate that the system is capable of producing effluent which is of a standard comparable to that expected from a traditional pervious pavement system and is acceptable for direct release into a surface water receptor. The system offers the opportunity to accrue the benefits of a pervious pavement when the use of traditional paving surfaces is the preferred option. PMID:23954068

Newman, Alan Paul; Aitken, Douglas; Antizar-Ladislao, Blanca

2013-12-15

211

Bearing capacity evaluation of rubblized concrete pavements  

Directory of Open Access Journals (Sweden)

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 DCP, Deflectómetro de Impacto Liviano, FWD (sobre carpeta asfáltica y excavando calicatas bajo el material triturado. La capacidad estructural del material triturado se realizó a través de un análisis teórico. Debido al las características anisotrópicas del material triturado, los resultados son presentados utilizando el coeficiente estructural AASHTO. Los resultados del estudio permiten recomendar un rango para el coeficiente estructural del pavimento sometido al proceso de Rubblizing el cual para espesores de losa superior a 22 cm está entre 0,25 a 0,30.

González, M.

2009-03-01

212

Evaluation of Road Pavement Density Using Ground Penetrating Radar  

Directory of Open Access Journals (Sweden)

Full Text Available This study describes an analysis of Ground Penetrating Radar (GPR measurements at frequency range of 1.7-2.6 GHz to get a relationship between attenuation and density for nine road pavements slabs with different densities. There are about four different frequencies had been tested. The method is simple, fast, non-destructive and accurate way to determine the density of road pavement. Density is a one of the important parameter in order to determine the compressive strength of road pavement for road user safety. In laboratory, the measurement system consists of a signal generator (250 kHz-3 GHz as a source, spectrum analyzer (100 Hz-8 GHz, directional coupler with adapter and horn antenna. The first part of the measurement system setup is to determine the amplitude of transmitted wave (received signal strength. A few of received signal strength and attenuation for nine road pavement slab samples were taken at four different frequencies. An instantaneous method for measuring the density of road pavement was developed by using microwave reflection technique and free space method. The MATLAB software is used to analyze the measurement data and also for the graphs comparisons. At the end of this study, it is found that density plays an important factor in causing a major in the recorded signal strength as well as the differences of attenuation of the GPR signal.

RSA Raja Abdullah

2009-01-01

213

Asphalt Pavement Material Improvement: A Review  

Directory of Open Access Journals (Sweden)

Full Text Available The recycling of solid industrial wastes (SIW such as waste rubber tires and plastics will not only solve the global environmental problem of these SIW but also act as very promising modifiers for the improvement of engineering characteristics of the asphalt pavement material. The present work was concerned with assisting the interested readers to be familiarized with the paving material asphalt-modifiers obtained from SIW by providing historical perspective on its first invention and development. The paper has also provided highlights on common processes of asphalt mixture production. It was also worth mentioning that there are two asphalt production technologies: the warm mix asphalt (WMA and hot mix asphalt (HMA technologies, and the various advantages of using each one. Additionally, the paper has provided the reader with an overview of a number of case studies which were conducted by scientists and researchers for serious attempting to reach development and capturing significant properties of incorporating SIWs in civil engineering represented by scarp tires in form of crumb rubber (CR, plastics (polymers in their different forms.

Mohamed Sulyman

2014-10-01

214

Liquidity Risk and Distressed Equity  

DEFF Research Database (Denmark)

I show theoretically and empirically that cash holdings can help rationalize the low returns to distressed equity. In my model, levered firms with financing constraints optimally choose their cash holdings to eliminate liquidity risk and optimally default when insolvent. Using data on solvency, liquidity, and returns for US firms, I find evidence consistent with the model’s predictions: (1) In all solvency levels, the average firm holds enough liquid assets to cover its short-term liabilities; less solvent firms have (2) a higher fraction of their total assets in liquid assets and therefore (3) lower conditional betas and (4) lower returns; (5) the profits of long-short solvency strategies are highest among firms with low liquidity; and (6) the profits of long-short liquidity strategies are highest among firms with low solvency.

Medhat, Mamdouh

215

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

Energy Technology Data Exchange (ETDEWEB)

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)

Zornberg, J. G.

2014-02-01

216

Artificial intelligence modeling to evaluate field performance of photocatalytic asphalt pavement for ambient air purification.  

Science.gov (United States)

In recent years, the application of titanium dioxide (TiO?) as a photocatalyst in asphalt pavement has received considerable attention for purifying ambient air from traffic-emitted pollutants via photocatalytic processes. In order to control the increasing deterioration of ambient air quality, urgent and proper risk assessment tools are deemed necessary. However, in practice, monitoring all process parameters for various operating conditions is difficult due to the complex and non-linear nature of air pollution-based problems. Therefore, the development of models to predict air pollutant concentrations is very useful because it can provide early warnings to the population and also reduce the number of measuring sites. This study used artificial neural network (ANN) and neuro-fuzzy (NF) models to predict NOx concentration in the air as a function of traffic count (Tr) and climatic conditions including humidity (H), temperature (T), solar radiation (S), and wind speed (W) before and after the application of TiO? on the pavement surface. These models are useful for modeling because of their ability to be trained using historical data and because of their capability for modeling highly non-linear relationships. To build these models, data were collected from a field study where an aqueous nano TiO? solution was sprayed on a 0.2-mile of asphalt pavement in Baton Rouge, LA. Results of this study showed that the NF model provided a better fitting to NOx measurements than the ANN model in the training, validation, and test steps. Results of a parametric study indicated that traffic level, relative humidity, and solar radiation had the most influence on photocatalytic efficiency. PMID:24699867

Asadi, Somayeh; Hassan, Marwa; Nadiri, Ataallah; Dylla, Heather

2014-07-01

217

Evaluation of Common Maintenance Methods for Flexible Pavements  

Directory of Open Access Journals (Sweden)

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 for roads in Iraq.

Asma T. Ibraheem

2011-01-01

218

Performance of an enhanced pervious pavement system loaded with large volumes of hydrocarbons.  

Science.gov (United States)

Five litres of lubricating oil and two 8.5 litre batches of diesel were deposited on each of two hydraulically isolated experimental enhanced pervious pavement parking bays. The 50 mm aggregate subbases of the two bays were of either recycled concrete or crushed limestone. The bays were constructed in such a way that a near-surface gravity separator was created by the arranging of the outlet pipes such that a permanent pool of water was maintained in the system and water could only enter from below the level of any floating oil. Dissolved/dispersed hydrocarbons were measured at acceptable concentrations when monitoring was carried out over a period of approximately 5 months. The maximum concentration was 7.2 mg/l and of all the samples collected only 3% exceeded the 5 mg/l limit applied in the UK for a class 1 interceptor, and the majority of samples had hydrocarbon concentrations of less than 2 mg/l. Much more significant is the fact that no free product was discharged from either system up to the time the experiment was dismantled 2 years from the first oil application despite the fact that sufficient hydrocarbon had been added to each pavement to produce a film on a water surface of over 500 hectares. PMID:25225930

Newman, Alan P; Puehmeier, Tim; Shuttleworth, Andy; Pratt, Christopher J

2014-01-01

219

Performance of waste tyre rubber on model flexible pavement  

Directory of Open Access Journals (Sweden)

Full Text Available This paper investigates the performance of flexible pavement on expansive soil subgrade using gravel/flyash as subbase course with waste tyre rubber as a reinforcing material. It was observed that from the laboratory test results of direct shear and CBR, the gravel subbase shows better performance as compared to flyash subbase with different percentages of waste tyre rubber as reinforcing material. Cyclic load tests are also carried out in the laboratory by placing a circular metal plate on the model flexible pavements. It is observed that the maximum load carrying capacity associated with less value of rebound deflection is obtained for gravel reinforced subbase compared to flyash reinforced subbase.

D. S. V. Prasad

2009-08-01

220

Moral distress in medical education and training.  

Science.gov (United States)

Moral distress is the experience of cognitive-emotional dissonance that arises when one feels compelled to act contrary to one's moral requirements. Moral distress is common, but under-recognized in medical education and training, and this relative inattention may undermine educators' efforts to promote empathy, ethical practice, and professionalism. Moral distress should be recognized as a feature of the clinical landscape, and addressed in conjunction with the related concerns of negative role modeling and the goals and efficacy of medical ethics curricula. PMID:24146350

Berger, Jeffrey T

2014-02-01

221

Calibrating mechanistic-empirical pavement performance models with an expert matrix  

Energy Technology Data Exchange (ETDEWEB)

Proper management of pavement infrastructure requires pavement performance modelling. For the past 20 years, the Ontario Ministry of Transportation has used the Ontario Pavement Analysis of Costs (OPAC) system for pavement design. Pavement needs, however, have changed substantially during that time. To address this need, a new research contract is underway to enhance the model and verify the predictions, particularly at extreme points such as low and high traffic volume pavement design. This initiative included a complete evaluation of the existing OPAC pavement design method, the construction of a new set of pavement performance prediction models, and the development of the flexible pavement design procedure that incorporates reliability analysis. The design was also expanded to include rigid pavement designs and modification of the existing life cycle cost analysis procedure which includes both the agency cost and road user cost. Performance prediction and life-cycle costs were developed based on several factors, including material properties, traffic loads and climate. Construction and maintenance schedules were also considered. The methodology for the calibration and validation of a mechanistic-empirical flexible pavement performance model was described. Mechanistic-empirical design methods combine theory based design such as calculated stresses, strains or deflections with empirical methods, where a measured response is associated with thickness and pavement performance. Elastic layer analysis was used to determine pavement response to determine the most effective design using cumulative Equivalent Single Axle Loads (ESALs), below grade type and layer thickness.The new mechanistic-empirical model separates the environment and traffic effects on performance. This makes it possible to quantify regional differences between Southern and Northern Ontario. In addition, roughness can be calculated in terms of the International Roughness Index or Riding comfort Index, or in terms of performance as a Pavement Condition Index. This new model can be re-calibrated to apply to conditions other than Ontario conditions. Examples of various design situations were included. 10 refs., 7 tabs., 5 figs.

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

2001-07-01

222

Criteria for use of asphalt friction surfaces  

Science.gov (United States)

Upgrading pavements by application of asphalt friction surfaces is discussed. Guidelines are presented for deciding when it is appropriate to use various types of friction courses. The most common types of asphalt surfaces used to upgrade frictional characteristics of pavements are seal coats, open-graded mixes, and dense graded mixes. Information is given on current engineering practices, legal and regulatory considerations, and criteria for selection of appropriate types of asphalt friction courses.

Halstead, W. J.; Copas, T. L.; Pennock, H. A.; Shipman, A.

1983-11-01

223

CAUSES OF RESPIRATORY DISTRESS IN CHILDREN  

Directory of Open Access Journals (Sweden)

Full Text Available "nThere is a lack of large, prospective epidemiologic studies concerning acute lung injury (ALI and acute respiratory distress syndrome (ARDS in pediatric population. To determine the different causes of respiratory distress in children, we prepared a retrospective study and included the whole 567 children with respiratory distress referred to 17-Shahrivar Hospital, Rasht, Guilan. Using their medical files, data including age, sex, and causes of respiratory distress were collected. SPSS 13.0 (statistical software applied for statistical analysis. Pneumonia, asthma, and croup were the major causes of ARDS in children with a rate of 38.4, 19.04, and 16.5 percent, respectively. It seems that infectious factors are at the top of the list of ARDS causing factors which can be helpful to approach and manage such patients. We suggest vaccinating these at risk groups against common infectious factors such as H. Influenza and RSV which can cause either pneumonia or inducing asthma.

M M Karambin

2008-11-01

224

Writing wrongs: on narratives of moral distress.  

Science.gov (United States)

The perception that one is being forced to do wrong, or being prevented from doing the right thing, is often described in the most brutal terms, as a situation that feels like participating in the torture of another human being. The emotional force of the experience of moral distress, and the perception that one is powerless to do anything to change the situation producing moral distress, can make it hard to look at these experiences critically, and to imagine a different reality. Writing about the experience of moral distress is a way to look critically at this experience. This commentary discusses how these narratives explore moral distress in relation to the formation of professional identity, as a "dirty" experience, as a potential consequence of unrelieved moral uncertainty, in the care of "difficult" patients, and as a response to systemic problems. PMID:24407085

Berlinger, Nancy

2013-01-01

225

Predicting symptomatic distress in emergency services personnel.  

Science.gov (United States)

This study identified predictors of symptomatic distress in emergency services (EMS) personnel exposed to traumatic critical incidents. A replication was performed in 2 groups: 154 EMS workers involved in the 1989 Interstate 880 freeway collapse during the San Francisco Bay area earthquake, and 213 counterparts from the Bay area and from San Diego. Evaluated predictors included exposure, social support, and psychological traits. Replicated analyses showed that levels of symptomatic distress were positively related to the degree of exposure to the critical incident. Level of adjustment was also related to symptomatic distress. After exposure, adjustment, social support, years of experience on the job, and locus of control were controlled, 2 dissociative variables remained strongly predictive of symptomatic response. The study strengthens the literature linking dissociative tendencies and experiences to distress from exposure to traumatic stressors. PMID:7608348

Weiss, D S; Marmar, C R; Metzler, T J; Ronfeldt, H M

1995-06-01

226

Cortico-limbic morphology separates tinnitus from tinnitus distress  

Directory of Open Access Journals (Sweden)

Full Text Available Tinnitus is a common auditory disorder characterized by a chronic ringing or buzzing “in the ear.” Despite the auditory-perceptual nature of this disorder, a growing number of studies have reported neuroanatomical differences in tinnitus patients outside the auditory-perceptual system. Some have used this evidence to characterize chronic tinnitus as dysregulation of the auditory system, either resulting from inefficient inhibitory control or through the formation of aversive associations with tinnitus. It remains unclear, however, whether these “non-auditory” anatomical markers of tinnitus are related to the tinnitus signal itself, or merely to negative emotional reactions to tinnitus (i.e., tinnitus distress. In the current study, we used anatomical MRI to identify neural markers of tinnitus, and measured their relationship to a variety of tinnitus characteristics and other factors often linked to tinnitus, such as hearing loss, depression, anxiety, and noise sensitivity. In a new cohort of participants, we confirmed that people with chronic tinnitus exhibit reduced grey matter in ventromedial prefrontal cortex (vmPFC compared to controls matched for age and hearing loss. This effect was driven by reduced cortical surface area, and was not related to tinnitus distress, symptoms of depression or anxiety, noise sensitivity, or other factors. Instead, tinnitus distress was positively correlated with cortical thickness in the anterior insula in tinnitus patients, while symptoms of anxiety and depression were negatively correlated with cortical thickness in subcallosal anterior cingulate cortex (scACC across all groups. Tinnitus patients also exhibited increased gyrification of dorsomedial prefrontal cortex (dmPFC, which was more severe in those patients with constant (vs. intermittent tinnitus. Our data suggest that the neural systems associated with chronic tinnitus are different from those involved in aversive or distressed reactions to tinnitus.

AmberMLeaver

2012-04-01

227

Refining the Measurement of Distress Intolerance  

OpenAIRE

Distress intolerance is an important transdiagnostic variable that has long been implicated in the development and maintenance of psychological disorders. Self-report measurement strategies for distress intolerance have emerged from several different models of psychopathology and these measures have been applied inconsistently in the literature in the absence of a clear gold standard. The absence of a consistent assessment strategy has limited the ability to compare across studies and samples...

Mchugh, R. Kathryn; Otto, Michael W.

2011-01-01

228

Deposit Withdrawals from Distressed Commercial Banks  

OpenAIRE

We study retail deposit withdrawals from European commercial banks which incurred investment losses in the wake of the U.S. subprime crisis. We document a strong propensity of households to withdraw deposits from distressed banks, especially when a bank receives a public bailout. However, the withdrawal risk for a distressed bank is mitigated by strong bank-client relationships and household-level switching costs: Households which rely on a single deposit account, which do not live close to a...

Martin Brown; Stefan Morkötter; Benjamin Guin

2014-01-01

229

/ Distress, demoralization and psychopathology: Diagnostic boundaries  

Scientific Electronic Library Online (English)

Full Text Available Background and Objectives: The objectives of the manuscript are: (a) to review the understanding of demoralization and its assessment; (b) to describe its clinical progression; (c) to explain the differences between demoralization and other form of psychological distress; (d) to propose a set of cri [...] teria for future research on demoralization. Methods: A MEDLINE search using the keywords distress, subjective incompetence, depression, demoralization, helplessness, hopelessness and psychopathology was conducted. This was supplemented by a manual search of the literature. Results: Demoralization can be distinguished from passing or transient distress, non-specific distress, sub-threshold depression or anxiety, and certain mental disorders. Demoralization can be a risk factor for the manifestation of psychopathology, the prodromal phase of a mental disorder, or a trigger for exacerbation or recurrence of psychiatric distress symptoms. The domains of distress and demoralization are described and research diagnostic criteria for demoralization are presented. Conclusions: The scales discussed in this article differ in their time frames and have not yet been applied to the same population at the same time. The role of demoralization as a risk factor for mental disorders is just beginning to be understood. The domains and the diagnostic criteria for demoralization presented in this article need to be confirmed by epidemiological and empirical studies. Future research should continue to clarify its role in the pathogenesis of both mental disorders and physical illnesses and identify appropriate interventions for its arrest or prevention.

John M. de, Figueiredo.

2013-03-01

230

Monitoring pavement response and performance using in-situ instrumentation  

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-07-01

231

Some experience using a rolling weight deflectometer on airport pavements  

Science.gov (United States)

A laser based deflection tester is being developed by the Swedish National Road Administration. Forty sensors are mounted on a heavy truck to determine two transverse profiles. One profile constitutes an unloaded case. The other profile just behind the rear wheels of the vehicle constitutes the loaded case. The high sampling rate is adequate for filtering the macro texture of the pavement.

Lenngren, Carl A.

1995-07-01

232

A Detailed Study of Cbr Method for Flexible Pavement Design  

Directory of Open Access Journals (Sweden)

Full Text Available As per IRC recommendation, California Bearing Ratio (CBR value of subgrade is used for design of flexible pavements. California Bearing Ratio (CBR value is an important soil parameter for design of flexible pavements and runway of air fields. It can also be used for determination of sub grade reaction of soil by using correlation. It is one of the most important engineering properties of soil for design of sub grade of roads. CBR value of soil may depends on many factors like maximum dry density (MDD, optimum moisture content (OMC, liquid limit (LL, plastic limit (PL, plasticity index (PI, type of soil, permeability of soil etc. Besides, soaked or unsoaked condition of soil also affects the value. These tests can easily be performed in the laboratory. the estimation of the CBR could be done on the basis of these tests which are quick to perform, less time consuming and cheap, then it will be easy to get the information about the strength of subgrade over the length of roads, By considering this aspect, a number of investigators in the past made their investigations in this field and designed different pavements by determining the CBR value on the basis of results of low cost, less time consuming and easy to perform tests. In this study, attempts have been made to seek the values of CBR of different soil samples and correlate their CBR values for the design purpose of flexible pavement as per guidelines of IRC: SP: 37-2001.

Er. Devendra Kumar Choudhary

2014-06-01

233

Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates.  

Science.gov (United States)

Non-point-source pollution is a major source of ecological impairment in urban stream systems. Recent work suggests that coal-tar pavement sealants, used extensively to protect parking areas, may be contributing a large portion of the polycyclic aromatic hydrocarbon (PAH) loading seen in urban stream sediments. The hypothesis that dried coal-tar pavement sealant flake could alter the macroinvertebrate communities native to streams in Austin, TX was tested using a controlled outdoor laboratory type approach. The treatment groups were: control, low, medium, and high with total PAH concentrations (TPAH = sum of 16 EPA priority pollutant PAHs) of 0.1, 7.5, 18.4, & 300 mg/kg respectively. The low, medium, and high treatments were created via the addition of dried coal-tar pavement sealant to a sterile soil. At the start of the 24-day exposure, sediment from a minimally impacted local reference site containing a community of live sediment-dwelling benthic macroinvertebrates was added to each replicate. An exposure-dependent response was found for several stream health measures and for several individual taxa. There were community differences in abundance (P = 0.0004) and richness (P < 0.0001) between treatments in addition to specific taxa responses, displaying a clear negative relationship with the amount of coal-tar sealant flake. These results support the hypothesis that coal-tar pavement sealants contain bioavailable PAHs that may harm aquatic environments. PMID:19913343

Bryer, Pamela J; Scoggins, Mateo; McClintock, Nancy L

2010-05-01

234

Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates  

Energy Technology Data Exchange (ETDEWEB)

Non-point-source pollution is a major source of ecological impairment in urban stream systems. Recent work suggests that coal-tar pavement sealants, used extensively to protect parking areas, may be contributing a large portion of the polycyclic aromatic hydrocarbon (PAH) loading seen in urban stream sediments. The hypothesis that dried coal-tar pavement sealant flake could alter the macroinvertebrate communities native to streams in Austin, TX was tested using a controlled outdoor laboratory type approach. The treatment groups were: control, low, medium, and high with total PAH concentrations (TPAH = sum of 16 EPA priority pollutant PAHs) of 0.1, 7.5, 18.4, & 300 mg/kg respectively. The low, medium, and high treatments were created via the addition of dried coal-tar pavement sealant to a sterile soil. At the start of the 24-day exposure, sediment from a minimally impacted local reference site containing a community of live sediment-dwelling benthic macroinvertebrates was added to each replicate. An exposure-dependent response was found for several stream health measures and for several individual taxa. There were community differences in abundance (P = 0.0004) and richness (P < 0.0001) between treatments in addition to specific taxa responses, displaying a clear negative relationship with the amount of coal-tar sealant flake. These results support the hypothesis that coal-tar pavement sealants contain bioavailable PAHs that may harm aquatic environments.

Bryer, P.J.; Scoggins, M.; McClintock, N.L. [Lamar University, Beaumont, TX (United States). Dept. of Biology

2010-05-15

235

DEVELOPMENT OF A HYDROPHOBIC SUBSTANCE TO MITIGATE PAVEMENT ICE ADHESION  

Science.gov (United States)

The specific problem to which this report is addressed is the development of a hydrophobic substance to mitigate the adhesion of ice to pavement as an alternative to deicing chemicals. The factors involved in evaluating this concept are the following: Economics; safety; environme...

236

Nitrogen Transformations in Three Types of Permeable Pavement  

Science.gov (United States)

In 2009, USEPA constructed a 0.4-ha (1-ac) parking lot at the Edison Environmental Center in Edison, NJ, that incorporated three different permeable pavement types - permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA). The driving lanes...

237

Prediction of subgrade moisture conditions for purposes of pavement design  

OpenAIRE

The purpose of this paper is to summarize the procedures for determining moisture conditions in subgrade soils and make recommendations regarding the practical applications to pavement design. By using data from different moisture studies some moisture models were tested to demonstrate their capability of predicting ultimate moisture contents.

Correia, A. Gomes

1996-01-01

238

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

Directory of Open Access Journals (Sweden)

Full Text Available Expansive soil (Black cotton soil is very weak and does not have enough stability for any type of construction work. In pavement, subgrade layer is the bottommost layer underlying the base course or surface course. To make the subgrade soil stable, by improving its engineering properties is very essential. In the present work, stabilization of subgrade soil by using sand and cement (varying percentage of sand and constant percentage of cement by weight of soil is used to enhance the strength of subgrade soil. The purpose of this study is to determine the optimum dose of the stabilizer, which improves the strength of soil (CBR less than or equal to 2% to more than 7% which is suitable for pavement structure. To evaluate the strength of soil, various test have been performed such as sieve analysis, liquid limit, Plastic limit, Standard proctor test and CBR test in the laboratory. The result shows that the use of sand and cement in combination, increases the California Bearing Ratio values (CBR i.e. the strength of soil to a great extent.

Mrs. Neetu B. Ramteke *1 ,

2014-06-01

239

Long-term salt marsh recovery and pavement persistence at {sup M}etula` spill sites  

Energy Technology Data Exchange (ETDEWEB)

Three coastal sites oiled from the 1974 `Metula` oil spill in the Strait of Magellan were revisited in May 1998 to document oiling conditions 23.5 years after the spill. The sites revisited are in the Punta Espora area. Two are salt marshes and the third, an inter-tidal asphalt pavement. It was found that the marshes were still oil covered and bare of vegetation in most sections, although the tilling conducted in 1993 resulted in substantial increases in the number of plants that were able to recolonize. Application of fertilizer without tilling of the surface of the oil had no effect. By 1998 the oil, although still present, was weathered to a rubbery consistency. The large, 550 m. long asphalt pavement that had formed on the mixed-sediment beach remained, and showed relatively little change. Chemical analysis of the asphalt indicated extremely high degradation, including even some of the highly biodegradation-resistant biomarker compounds. The experimental treatment plots that were tilled in 1993 showed the highest level of weathered oil, and the highest degree of plant recolonization, suggesting that recolonization of the marshes could have been accelerated had tilling been conducted on these sites soon after the spill. 15 refs., 5 tabs., 6 figs.

Owens, E. H. [Polaris Applied Sciences, Bainbridge Island, WA (United States); Sergy, G. A. [Environment Canada, Edmonton, AB (Canada); Guzman, M. L. [Instituto de Fomento Pesquero, Punta Arenas (Chile); Wang, Z. [Environment Canada. Ottawa, ON (Canada); Baker, J. [Ruyton-XI-Towns (United Kingdom)

1999-08-01

240

Long-term salt marsh recovery and pavement persistence at Metula' spill sites  

International Nuclear Information System (INIS)

Three coastal sites oiled from the 1974 'Metula' oil spill in the Strait of Magellan were revisited in May 1998 to document oiling conditions 23.5 years after the spill. The sites revisited are in the Punta Espora area. Two are salt marshes and the third, an inter-tidal asphalt pavement. It was found that the marshes were still oil covered and bare of vegetation in most sections, although the tilling conducted in 1993 resulted in substantial increases in the number of plants that were able to recolonize. Application of fertilizer without tilling of the surface of the oil had no effect. By 1998 the oil, although still present, was weathered to a rubbery consistency. The large, 550 m. long asphalt pavement that had formed on the mixed-sediment beach remained, and showed relatively little change. Chemical analysis of the asphalt indicated extremely high degradation, including even some of the highly biodegradation-resistant biomarker compounds. The experimental treatment plots that were tilled in 1993 showed the highest level of weathered oil, and the highest degree of plant recolonization, suggesting that recolonization of the marshes could have been accelerated had tilling been conducted on these sites soon after the spill. 15 refs., 5 tabs., 6 figs

241

ROP GTPase-mediated auxin signaling regulates pavement cell interdigitation in Arabidopsis thaliana.  

Science.gov (United States)

In multicellular plant organs, cell shape formation depends on molecular switches to transduce developmental or environmental signals and to coordinate cell-to-cell communication. Plants have a specific subfamily of the Rho GTPase family, usually called Rho of Plants (ROP), which serve as a critical signal transducer involved in many cellular processes. In the last decade, important advances in the ROP-mediated regulation of plant cell morphogenesis have been made by using Arabidopsis thaliana leaf and cotyledon pavement cells. Especially, the auxin-ROP signaling networks have been demonstrated to control interdigitated growth of pavement cells to form jigsaw-puzzle shapes. Here, we review findings related to the discovery of this novel auxin-signaling mechanism at the cell surface. This signaling pathway is to a large extent independent of the well-known Transport Inhibitor Response (TIR)-Auxin Signaling F-Box (AFB) pathway, and instead requires Auxin Binding Protein 1 (ABP1) interaction with the plasma membrane-localized, transmembrane kinase (TMK) receptor-like kinase to regulate ROP proteins. Once activated, ROP influences cytoskeletal organization and inhibits endocytosis of the auxin transporter PIN1. The present review focuses on ROP signaling and its self-organizing feature allowing ROP proteins to serve as a bustling signal decoder and integrator for plant cell morphogenesis. PMID:25168157

Lin, Deshu; Ren, Huibo; Fu, Ying

2015-01-01

242

Mechanistic modelling of weak interlayers in flexible and semi-flexible road pavements: Part 2  

Scientific Electronic Library Online (English)

Full Text Available This paper (Part 2 of a two-part set of papers) discusses models and illustrates the adverse effects of weak layers, interlayers, laminations and/or weak interfaces in flexible and semi-flexible pavements, also incorporating lightly cemented layers. The modelling is based on mechanistic analyses for [...] pavement design and evaluation. In Part 1, the effects of these relatively weak layers, interlayers, laminations and/or weak interfaces were discussed. It was shown that methodologies are available to detect and investigate the existence of these weak layers in cemented pavement layers. In Part 2, several cases of the above conditions for different road pavement types are discussed, with field examples. Mechanistic analyses were done on a typical hot mix asphalt (HMA), several cases of a cemented base pavement and a granular base pavement, with and without these weak layers and interface conditions to demonstrate their adverse effects. The analyses focus on the strain energy of distortion (SED) as a pavement response parameter to indicate the potential for structural damage expected within the pavement structure or layer. Generally, the higher the SED, the higher the potential damage in the pavement layer. SED shows some potential for quantifying the relative effects of these weak layers, interlayers, laminations and/or weak interfaces within flexible and semi-flexible pavements.

M, de Beer; J W, Maina; F, Netterberg.

2012-04-01

243

Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates  

International Nuclear Information System (INIS)

Non-point-source pollution is a major source of ecological impairment in urban stream systems. Recent work suggests that coal-tar pavement sealants, used extensively to protect parking areas, may be contributing a large portion of the polycyclic aromatic hydrocarbon (PAH) loading seen in urban stream sediments. The hypothesis that dried coal-tar pavement sealant flake could alter the macroinvertebrate communities native to streams in Austin, TX was tested using a controlled outdoor laboratory type approach. The treatment groups were: control, low, medium, and high with total PAH concentrations (TPAH = sum of 16 EPA priority pollutant PAHs) of 0.1, 7.5, 18.4, and 300 mg/kg respectively. The low, medium, and high treatments were created via the addition of dried coal-tar pavement sealant to a sterile soil. At the start of the 24-day exposure, sediment from a minimally impacted local reference site containing a community of live sediment-dwelling benthic macroinvertebrates was added to each replicate. An exposure-dependent response was found for several stream health measures and for several individual taxa. There were community differences in abundance (P = 0.0004) and richness (P < 0.0001) between treatments in addition to specific taxa responses, displaying a clear negative relationship with the amount of coal-tar sealant flake. These results support the hypothesis that coal-tar pavement sealants contain bioavailable PAHs that may harm aquatic environments. - Coal-tar may harm aquatic environments. - Coal-tar pavement sealants degrade stream invertebrate communities.

244

Filtration and clogging of permeable pavement loaded by urban drainage.  

Science.gov (United States)

Permeable pavement, as a sustainable infrastructure material can promote hydrologic restoration, particulate matter (PM) and solute control. However, filtration and commensurate clogging are two aspects of continued interest and discussion. This study quantifies filtration and clogging of cementitious permeable pavement (CPP) for loadings from 50 to 200 mg/L of hetero-disperse sandy-silt PM. The CPP mix design provides a hetero-disperse pore size distribution (PSD)(pore), effective porosity (?(e)) of 24% and median pore size of 658 ?m with a standard deviation of 457 ?m. The PM mass separation across the entire particle size distribution (PSD)(PM) exceeds 80%; with complete separation for PM greater than 300 ?m and 50% separation for suspended PM. Turbidity is reduced (42-95%), and effluent is below 10 NTU in the first quartile of a loading period. Permeable pavement illustrates reductions in initial (clean-bed) hydraulic conductivity (k(0)) with loading time. For all PM loadings, k(0) (3.1 × 10(-1) mm/s) was reduced to 10(-4) mm/s for runoff loading durations from 100 to 250 h, respectively. Temporal hydraulic conductivity (k) follows exponential profiles. Maintenance by vacuuming and sonication illustrate that 96-99% of k(0) is recovered. Permeable pavement constitutive properties integrated with measured PM loads and a year of continuous rainfall-runoff simulation illustrate k reduction with historical loadings. Study results measure and model filtration and hydraulic conductivity phenomena as well as maintenance requirements of permeable pavement directly loaded by urban drainage. PMID:22123518

Sansalone, J; Kuang, X; Ying, G; Ranieri, V

2012-12-15

245

Application of CalME incremental-recursive method to the evaluation of the structural condition as asphalt pavements; Aplicacion del metodo recursivo-incremental CalME a la evaluacion del estado estructural de los pavimentos bituminosas  

Energy Technology Data Exchange (ETDEWEB)

CalME procedure represents one of the most advanced tools for the design, of flexible pavements world-wide. It is an incremental-recursive method, which means that pavements service life must be divided into many time intervals where both structural integrity and environmental conditions can be regarded as constants. It also means that the damage calculated at the end of each interval must be considered as initial condition for the next one. The goal of this type of models is the prediction of the evolution of the different distress mechanisms. The advantages of incremental-recursive procedures versus classical analytical design are shown in this paper. Advantages are shown not only in terms of design, but also as a tool in order to support structural evaluation. In particular, the potential of asphalt fatigue model incorporated in CalME is presented. this model is initially calibrated in the laboratory, and it is then re-calibrated based on the actual performance observed from field deflection testing. The model provides a reliable prediction of the future evolution of the damage of the asphalt mixture. Fatigue model validation has been conducted based on the performance from several flexible sections evaluated in CEDEX full-scale pavements test track. (Author) 14 refs.

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

2011-07-01

246

Research on the characteristics of temperature field of asphalt pavement in seasonal frozen region  

Science.gov (United States)

The characteristics of climate in seasonal frozen area are low temperature and a large range of temperature variation between day and night in winter. These characteristics often lead to problems of asphalt pavement, especially transverse cracks. To reduce the problems of asphalt pavement, it is necessary to examine the distribution of the temperature range of asphalt pavement. A three-dimensional finite element model was used, taking the SMA asphalt pavement as an example with solid70 and plane55 unit features of ANSYS software. It can obtain the relationship between temperature gradient and time and the relationship between temperature gradient and depth. In addition, a function relation model of stress and time was also established. It can provide a theoretical basis for the prevention and treatment of problems of asphalt pavement in seasonal frozen area. Moreover, it has an important significance for improving asphalt pavement design.

Qiao, Jiangang; Liu, Weizheng

2014-08-01

247

Analysis of engineering characteristics of pavement deflection trends  

Energy Technology Data Exchange (ETDEWEB)

This paper describes analysis of pavement deflection data collected by the Transport Research Laboratory at two experimental road sites in England during 1960--1985. Measurements of Benkelman beam deflections together with records of traffic loading were taken at 6 to 12 month intervals. The analysis investigates the deflection trend as a function of road base material and thickness. The deflection trend was represented by a negative exponential curve form. Engineering aspects of the curve form were extracted and statistically analyzed. The results obtained focus on the dependency of deflection progression on both road base material and thickness, which are shown to act either jointly or singly, depending on the engineering characteristic of the pavement deflection trend.

Kerali, H.R.; Lawrance, A.J. [Univ. of Birmingham (United Kingdom)

1999-05-01

248

Design Methodologies of Asphalt Pavement Used in China and Mozambique  

Directory of Open Access Journals (Sweden)

Full Text Available This study discusses and compares Asphalt Concrete (AC pavement design methodologies used in China and Mozambique (based on South African Transportation and Communication Commission (SATCC methodologies. The SATCC design methodologies use California Bearing Ratio (CBR and catalogues methods. The South African catalogues are basically used for roads with traffic less than 30 million ESAs. The design catalogues method give small thickness than CBR and Chinese methods. The Chinese and the South African design methods give nearly the same thickness; this study concludes that these methods can be used in both countries; China and Mozambique. The results also show that the strong point of Chinese method is verifying the tensile stress and allowable displacement on the pavement calculated from computer program APDS.

Jose Francisco Rufino Diogo

2007-01-01

249

Design Methodologies of Asphalt Pavement Used in China and Mozambique  

Science.gov (United States)

This study discusses and compares Asphalt Concrete (AC) pavement design methodologies used in China and Mozambique (based on South African Transportation and Communication Commission (SATCC) methodologies). The SATCC design methodologies use California Bearing Ratio (CBR) and catalogues methods. The South African catalogues are basically used for roads with traffic less than 30 million ESAs. The design catalogues method give small thickness than CBR and Chinese methods. The Chinese and the South African design methods give nearly the same thickness; this study concludes that these methods can be used in both countries; China and Mozambique. The results also show that the strong point of Chinese method is verifying the tensile stress and allowable displacement on the pavement calculated from computer program APDS.

Francisco Rufino Diogo, Jose; Shubber, Ammar Abbas Mohammed; Lin, Mu Han

250

Use of Recycled Aggregate and Fly Ash in Concrete Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Recycled materials aggregate from the demolished concrete structures and fly ash from burning coal shows the possible application as structural and non structural components in concrete structures. This research aims to evaluate the feasibility of using concrete containing recycled concrete aggregate and fly ash in concrete pavement. Approach: Two water cement ratio (0.45 and 0.55 the compressive strength, modulus of electricity and flexural strength for concrete with recycled aggregate and fly ash with 0, 25% replacing cement in mass were considered. Results: The material properties of recycled aggregate concrete with fly ash indicate comparable results with that of concrete with natural aggregate and without fly ash. Conclusion/Recommendations: The recycled materials could be used in concrete pavement and it will promote the sustainability of concrete.

Myle N. James

2011-01-01

251

Evaluation of flexible pavement crack sealing methods used in Utah  

Science.gov (United States)

Criteria to improve the effectiveness of Utah's flexible pavements crack sealing practice were studied. Field measurements, in-depth interviews questionaires were used. Findings indicate that flexible pavement cracking is a significant problem in the Far West, Rocky Mountains, Great Lakes and New England. Choice of materials is effected by storage requirements and equipment available. Prepackaging of materials designed for crack sealing has resulted in improvements in control of mix and material properties. Low temperature and freeze thaw cycles significantly effect the amount of thermal cracking and the performance of crack sealant. Ductile sealants, such as Crumb rubber/asphalt cement mixes, in combination with routing appear to offer substantial gains in sealant life and performance.

Belangie, M. C.; Anderson, D. I.

1981-01-01

252

Identification and conversion of foundation parameters for airport pavement  

Science.gov (United States)

The least squares method has been employed to fit measured and theoretical curves for the deflection of airport pavements, with the aim of identifying modulus of resilience E0 and of reaction K. Using these moduli results in errors generally no larger than 10 percent. A more accurate method of converting E0 into K and vice versa is proposed. The error is generally about 1 percent with maximum error not exceeding 2.7 percent.

Shang, Shiying; Wang, Shangwen

1993-01-01

253

Design Methodologies of Asphalt Pavement Used in China and Mozambique  

OpenAIRE

This study discusses and compares Asphalt Concrete (AC) pavement design methodologies used in China and Mozambique (based on South African Transportation and Communication Commission (SATCC) methodologies). The SATCC design methodologies use California Bearing Ratio (CBR) and catalogues methods. The South African catalogues are basically used for roads with traffic less than 30 million ESAs. The design catalogues method give small thickness than CBR and Chinese methods. The Chinese and the So...

Jose Francisco Rufino Diogo; Ammar Abbas Mohammed Shubber; Mu Han Lin

2007-01-01

254

DYNAMIC JOINT LOAD TRANSFER EFFICIENCY OF RIGID PAVEMENT  

Directory of Open Access Journals (Sweden)

Full Text Available the mechanistic analysis presented in this paper is only the beginning of new approach for understanding the real joint load transfer capability on airport and highway concrete pavements. It gives up the two major assumptions those have been popularly adopted by hundreds of published papers: the load is transferred under a wheel with zero speed and with fixed position. The real load transfer in field is always under wheels with non-zero speed and with varied position at any moment. The objective of this study focuses on quantifying the dynamic effects of a moving wheel while it is crossing a joint on a pavement. The analysis is conducted using a model of two-slab system on Kelvin foundation under a moving wheel with variable speed v, different pavement damping Cs, foundation reaction modulus k and foundation damping Ck. The dynamic joint load transfer efficiency is temporarily and empirically defined by the peak strain ratio LTE(S on the two sides of a joint. The primary findings include: (1 The higher speed of a moving wheel leads to the higher LTE(S;(2 The larger the pavement damping Cs leads to the higher LTE(S;(3 The numerical ratio c(=LTE(Sdynamic/ LTE(Sstatic varies in the range 1 to 2 mainly depending on speed v and damping Cs;(4 The LTE(Sdynamic is not sensitive to foundation reaction modulus k and foundation damping Ck. Further researches are needed for appropriate applications of the new model in practice.

YU Xinhua

2011-02-01

255

Combined permeable pavement and ground source heat pump systems  

OpenAIRE

The PhD thesis focuses on the performance assessment of permeable pavement systems incorporating ground source heat pumps (GSHP). The relatively high variability of temperature in these systems allows for the survival of pathogenic organisms within the sub?base. Salmonella sp, Escherichia coli, Enterococci and total heterotrophic bacteria were analysed in order to assess potential risk to health. Supplementary carbon dioxide monitoring indicated relatively high microbial activity on the geo...

Grabowiecki, Piotr

2010-01-01

256

Innovations in design and construction of granular pavements and railways  

OpenAIRE

This paper describes some of the work related with the International Technical Committee TC3 – Geotechnics of Pavements of ISSMGE. For brevity, some topics are selected to be described in some detail, while others are acknowledged for reference purposes. These topics cover: (1) Data Mining tools in transporttation geotechnics showing the capabilities to predict real-value from several attributes and also the possibility to develop a formal updating framework to reduce uncertainty a...

Correia, A. Gomes

2008-01-01

257

In-situ determination of moisture in road pavement by nuclear methods  

International Nuclear Information System (INIS)

The use of neutron moisture probes to determine moisture in compacted pavement layers has been studied on samples representative of those used by the New South Wales Department of Main Roads for roadway construction. The aim of this work was to measure the average moisture content of the upper layer (15-20 cm thick) with minimum interference from moisture in underlying layers. Sub-surface probes using high (?-Be) and low (?-Li) energy neutron sources were examined; conventional ?-Be sources in specially designed compact probes should result in an error due to base moisture and density variations of less than 0.4 wt % moisture. As this error is probably less than those due to sampling and geometry variations in the field, such a probe should be sufficiently accurate for DMR requirements. If less sensitivity to base moisture is required, the ?-Li source will reduce this sensitivity by a factor of about 1.4

258

The impact of light-colored pavements on active layer dynamics revealed by Ground-Penetrating Radar monitoring  

OpenAIRE

Ground-penetrating radar (GPR) has been used to study the variations in the depth of the frost table throughout a complete thaw-freeze season in Kangerlussuaq Airport, western Greenland. In autumn 2000, three test areas were painted white on the parking area of the airport in order to reduce further development of depressions in the asphalt pavement. One of these areas has been used in the GPR investigations to compare the variations of the frost table underneath a normal dark asphalt surface...

Jørgensen, Anders Stuhr; Ingeman-nielsen, Thomas

2008-01-01

259

Reliability-based performance simulation for optimized pavement maintenance  

International Nuclear Information System (INIS)

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

260

Truck fleet model for design and assessment of flexible pavements  

Science.gov (United States)

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 which aims to reproduce the mean and variance of dynamic loading of the truck fleet at a given site is developed here. This probabilistic model reflects the range and frequency of the different heavy trucks on the road and their dynamic properties. Multiple Sensor Weigh-in-Motion data can be used to calibrate the model. Truck properties such as suspension stiffness, suspension damping, sprung mass, unsprung mass and tyre stiffness are represented as randomly varying parameters in the fleet model. It is used to predict the statistical distribution of dynamic load at each measurement point. The concept is demonstrated by using a pre-defined truck fleet to calculate a pattern of statistical spatial repeatability and is tested by using that pattern to find the truck statistical properties that generated it.

Belay, Abraham; OBrien, Eugene; Kroese, Dirk

2008-04-01

261

Performance of Recycled Asphalt Pavement as Coarse Aggregate in Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available Recycled asphalt pavement (RAP is the reclaimed and reprocessed pavement material containing asphalt and aggregate. Most RAP is recycled back into pavements, and as a result there is a general lack of data pertaining to the mechanical properties for RAP in other possible applications such as Portland cement concrete. In the present study, some mechanical properties of Portland cement concrete containing RAP as coarse aggregate were investigated in the laboratory. Six concrete mixes of widely differing water/cement ratios and mix proportions were made using RAP as coarse aggregate. The properties tested include the physical properties of the RAP aggregate, the compressive and flexural strengths of the concrete. These properties were compared with those of similar concretes made with natural gravel aggregate. Results of the tests suggest that the strength of concrete made from RAP is dependent on the bond strength of the ?asphalt-mortar? (asphalt binder-sand-filler matrix coatings on the aggregates and may not produce concrete with compressive strength above 25 MPa. However, for middle and low strength concrete, the material was found to compare favorably with natural gravel aggregate.

Fidelis O. OKAFOR

2010-12-01

262

Patología de pavimentos articulados Pathology of interlocking pavements  

Directory of Open Access Journals (Sweden)

Full Text Available Este artículo presenta los resultados de un proyecto de grado sobre patología de pavimentos articulados, el cual fue elaborado con el propósito de hacer una recolección de los deterioros típicos de los pavimentos articulados construidos con adoquines de concreto o de ladrillo; y de esta forma, elaborar un catálogo de deterioros para este tipo de estructuras que facilitará la identificación y cuantificación de los deterioros en una inspección visual. El segundo propósito de este proyecto, es la formulación para Colombia de una metodología que permita determinar el Índice de Condición de las estructuras de pavimentos articulados.This article presents the results of a thesis on pathology of interlocking pavements, which objective was to make a compilation of typical damages of interlocking pavements constructed with concrete or brick pavers and, in this way, to elaborate a catalogue of damages for this kind of structures which will make the identification and quantification of deteriorations possible in a visual inspection. The second purpose of this project is the formulation of a methodology which allows determining the Index of pavement conditions for Colombia.

Carlos Hernando Higuera Sandoval

2010-07-01

263

Full scale demonstration of air-purifying pavement  

Energy Technology Data Exchange (ETDEWEB)

Highlights: ? The results of a demonstration project for photocatalytic pavement are shown. ? The photocatalytic performance was studied in a street as well as on lab scale. ? The outdoor monitoring was performed in different seasons and weather conditions. ? The NO{sub x} concentration was in average 19% lowered by the photocatalytic street. ? Under ideal weather conditions the NO{sub x} reduction reached up to 45%. -- Abstract: Experiments concerning a full-scale demonstration of air purifying pavement in Hengelo, The Netherlands, are reported. The full width of the street was provided with concrete pavement containing TiO{sub 2} over a length of 150 m (“DeNO{sub x} street”). Another part of the street, about 100 m, was paved with normal paving blocks (“Control street”). The outdoor monitoring was done during 26 days for a period exceeding one year, and measured parameters included traffic intensity, NO, NO{sub 2} and ozone concentrations, temperature, relative humidity, wind speed and direction, and the visible and UV light irradiance. Prior and parallel to these field measurements, the used blocks were also measured in the lab to assess their performance. The NO{sub x} concentration was, on average, 19% (considering the whole day) and 28% (considering only afternoons) lower than the obtained values in the Control street. Under ideal weather conditions (high radiation and low relative humidity) a NO{sub x} concentration decrease of 45% could be observed.

Ballari, M.M., E-mail: ballari@santafe-conicet.gov.ar [Department of the Built Environment, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Brouwers, H.J.H., E-mail: jos.brouwers@tue.nl [Department of the Built Environment, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2013-06-15

264

Full scale demonstration of air-purifying pavement  

International Nuclear Information System (INIS)

Highlights: ? The results of a demonstration project for photocatalytic pavement are shown. ? The photocatalytic performance was studied in a street as well as on lab scale. ? The outdoor monitoring was performed in different seasons and weather conditions. ? The NOx concentration was in average 19% lowered by the photocatalytic street. ? Under ideal weather conditions the NOx reduction reached up to 45%. -- Abstract: Experiments concerning a full-scale demonstration of air purifying pavement in Hengelo, The Netherlands, are reported. The full width of the street was provided with concrete pavement containing TiO2 over a length of 150 m (“DeNOx street”). Another part of the street, about 100 m, was paved with normal paving blocks (“Control street”). The outdoor monitoring was done during 26 days for a period exceeding one year, and measured parameters included traffic intensity, NO, NO2 and ozone concentrations, temperature, relative humidity, wind speed and direction, and the visible and UV light irradiance. Prior and parallel to these field measurements, the used blocks were also measured in the lab to assess their performance. The NOx concentration was, on average, 19% (considering the whole day) and 28% (considering only afternoons) lower than the obtained values in the Control street. Under ideal weather conditions (high radiation and low relative humidity) a NOx concentration decrease of 45% could be observed

265

Patología de pavimentos articulados / Pathology of interlocking pavements  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Este artículo presenta los resultados de un proyecto de grado sobre patología de pavimentos articulados, el cual fue elaborado con el propósito de hacer una recolección de los deterioros típicos de los pavimentos articulados construidos con adoquines de concreto o de ladrillo; y de esta forma, elabo [...] rar un catálogo de deterioros para este tipo de estructuras que facilitará la identificación y cuantificación de los deterioros en una inspección visual. El segundo propósito de este proyecto, es la formulación para Colombia de una metodología que permita determinar el Índice de Condición de las estructuras de pavimentos articulados. Abstract in english This article presents the results of a thesis on pathology of interlocking pavements, which objective was to make a compilation of typical damages of interlocking pavements constructed with concrete or brick pavers and, in this way, to elaborate a catalogue of damages for this kind of structures whi [...] ch will make the identification and quantification of deteriorations possible in a visual inspection. The second purpose of this project is the formulation of a methodology which allows determining the Index of pavement conditions for Colombia.

Carlos Hernando, Higuera Sandoval; Óscar Fabián, Pacheco Merchán.

2010-07-01

266

Reliability-based performance simulation for optimized pavement maintenance  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-10-15

267

Distress Screening in Chronic Disease: Essential for Cancer Survivors  

OpenAIRE

Distress is a psychological state that is often observed in patients with chronic disease. Many cancers are considered chronic in nature, with patients experiencing long, disease-free states and intervals of metastatic disease. Distress can negatively affect the biopsychosocial balance in cancer survivors and impede their progress along the cancer trajectory. Distress can also affect medical and psychological outcomes and hinder advancement into long-term survivorship. Distress may contribute...

Petty, Lorie; Lester, Joanne

2014-01-01

268

Permeability measurement and scan imaging to assess clogging of pervious concrete pavements in parking lots.  

Science.gov (United States)

This paper describes a study that used permeability measurement along with physical and hydrological characteristics of 20 pervious concrete pavements in parking lots throughout California. The permeability was measured at five locations: the main entrance, an area with no traffic, and three separate measurements within a parking space at each parking lot. Hydrological and physical site characteristics such as traffic flow, erosion, vegetation cover, sediments accumulation, maintenance practice, presence of cracking, rainfall, and temperature data were also collected for each parking lot. These data were used to perform detailed statistical analysis to determine factors influencing changes in permeability and hence assessing possible cause of clogging. In addition, seven representative core samples were obtained from four different parking lots with permeability ranging from very low to very high. Porosity profiles produced from CT scanning were used to assess the possible nature and extent of clogging. Results showed that there is a large variation in permeability within each parking lot and between different parking lots. In general, the age of the parking lot is the predominant factor influencing the permeability. Statistical analysis revealed that fine sediment (particles less than 38 ?m) mass is also an important influencing factor. Other influencing factors with lower significance included number of days with a temperature greater than 30°C and the amount of vegetation next to the parking lot. The combined scanned image analysis and porosity profile of the cores showed that most clogging occurs near the surface of the pavement. While lower porosity generally appeared to be limited to the upper 25 mm, in some core samples evidence of lower porosity was found up to 100mm below the surface. PMID:22115516

Kayhanian, Masoud; Anderson, Dane; Harvey, John T; Jones, David; Muhunthan, Balasingam

2012-03-01

269

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

Science.gov (United States)

In the recent decades, Public-Private Partnerships (PPP) has been adopted for highway infrastructure procurement in many countries. PPP projects typically take the form of a section of highway and connecting roadways which are to be construction and managed for a given concession period. Over the course of the highway concession period, the private agency takes over the pavement maintenance and rehabilitation duties. On this purpose, it is critical to find the most cost effective way to maintain the infrastructure in compliance with the agreed upon performance measures and a Pavement Management Systems (PMS) is critical to the success of this process. For the prosperous operation of a PMS it is necessary to have appropriate procedures for pavement monitoring and evaluation, which is important in many areas of pavement engineering. Non Destructive Testing (NDT) has played a major role in pavement condition monitoring, assessments and evaluation accomplishing continuous and quick collection of pavement data. The analysis of this data can lead to indicators related to trigger values (criteria) that define the pavement condition based on which the pavement "health" is perceived helping decide whether there is the need or not to intervene in the pavement. The accomplished perception appoints required management activities for preserving pavements in favor not only of the involved highway/road agencies but also of users' service. Amongst NDT methods Ground Penetrating Radar (GPR) seems to be a very powerful toll, as it provides a range of condition and construction pavement information. It can support effectively the implementation of PMS activities in the framework of pavement monitoring and evaluation. Given that, the present work aims to the development and adaptation of a protocol for the use of GPR in combination with other NDT methods, such as Falling Weight Deflectometer (FWD), for assessing pavements in PPP projects. It is based on the experience of Laboratory of Pavement Engineering of National Technical University of Athens (NTUA) gained through its research activities in various Greek PPP projects as well its involvement in several related European and International scientific actions. It is suggested that the implementation of such protocol could support the pavement management activities with respect to the needs of a PPP project. This is accomplished through the resulted advantages that include simplicity in application, economic benefits and familiarity that are very important factors towards the optimization of the resources and the utilization of the available information; both of them are required for the orderly operation of a PPP project. Acknowledgments: This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

Loizos, Andreas; Plati, Christina

2014-05-01

270

Negative Emotions and Behaviors are Markers of Breakup Distress  

Science.gov (United States)

Method: University students who experienced a recent romantic breakup were given several self-report measures and were then divided into high versus low breakup distress groups. Results: The high breakup distress versus the low breakup distress groups had higher scores on negative emotions scales including depression, anxiety and anger and…

Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeanette

2013-01-01

271

33 CFR 175.130 - Visual distress signals accepted.  

Science.gov (United States)

...Orange Smoke Distress Signals Day Only 3 160.024 Parachute Red Flare Distress Signals Day and Night 1 3 160.036 Hand-Held Rocket-Propelled Parachute Red Flare Distress Signals Day and Night 3 160.037...

2010-07-01

272

Development of an evaporation-optimized and water-permeable pavement  

Science.gov (United States)

During recent decades, urban areas have been threatened more frequently by flood events. Furthermore, the potential for damage from these events has increased on average. The construction of houses, streets and parking lots has caused this trend by sealing the ground surface, i.e. these water-impermeable areas reduce the natural infiltration and evaporation-rates, and in some cases it is even completely stopped. The consequence is the so called "urban water cycle". Water from precipitation cannot be stored anywhere and so there is an immediate and very high surface run-off effect. Especially after intense rain events, canalisations and sewage-treatment plants are overloaded and this leads to higher costs for water treatment and to environmental damage. A practical solution to this problem is the use of water-permeable pavements. Here higher infiltration rates lead to a groundwater recharge that is greater than that of natural soils. The consequences from using these surfaces are already noticeable in many places through increasing groundwater levels. These increases cause damage to buildings. A second difference from a natural-soil water-balance is a lower evapotranspiration rate. Up to now the evaporation rates for water-permeable pavements has not been established accurately. The aim of the applied research project at the University of Muenster, which is sponsored by the DBU (The German Federal Environmental Foundation), is to gain knowledge of urban evaporation rates and of water-permeable surfaces, especially water-permeable pavements. Water-permeable pavements consist of the paving stone surface and the two sub-base layers below. Pre-investigations show that evaporation can be influenced by the complete sub-base. Therefore, the first step was to investigate which materials are used for sub-base construction. All in all, 27 materials were collected from throughout Germany and these materials were then tested (in terms of physical and hydraulic attributes) in the soil-mechanics laboratory of the University of Muenster. For their street construction useability, and having regard to evaporation, a selection of appropriate materials were built into a test field. The test field consisted of seven hexagonal areas each about 10 m2 large, which are placed in a honeycomb manner. The evaporation measurements are carried out with a WERNER tunnel-evaporation gauge (TUV) which is able to detect the actual evaporation rate. Its functional principle also allows a direct comparison between the middle reference area and one outer area of the test field. Every measuring period lasts one week and after that the TUV is moved to between the next outer area and the reference area. So the TUV rotates over the whole test field and every measuring area is covered by a measurement. In addition, a Hellman rain-gauge near the test field enables the measurement of a direct precipitation-evaporation ratio. Since the start of the measurements in July 2008, the first results collected showed that measureable differences in evaporation rates could be detected after a few measuring periods, i.e. the differences are up to 32% between the reference area and one outer area. In July 2009, the six outer measuring areas of the test field will be replaced and, based on the actual results collected, the sub-base layers will be replaced by an evaporation-optimized sub-base. The new outer measuring areas will only differ in terms of a different paving-stone surface. These paving stones are actually under developement and under laboratory testing (i.e. permeability, porosity, capillary water and evaporationrates), and so they will be evaporation-opimized. The open-air test in the test field is to assure and compare the evaporation rates. As a final result, the evaporation-optimized and water-permeable pavement and the knowledge of its exact drainage ratio will allow city planners or architects to build water-permeable streets with due regard to the respective area-specific conditions. This new developed pavement is an approximation to the water balanc

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

2009-04-01

273

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

OpenAIRE

Pavement-watering as a technique of cooling dense urban areas and reducing the urban heat island effect has been studied since the 1990's. The method is currently considered as a potential tool for and climate change adaptation against increasing heat wave intensity and frequency. However, although water consumption necessary to implement this technique is an important aspect for decision makers, optimization of possible watering methods has only rarely been conducted. We propose an analysis ...

Hendel, Martin; Colombert, Morgane; Diab, Youssef; Royon, Laurent

2014-01-01

274

Disordered Eating and Psychological Distress among Adults  

Science.gov (United States)

The majority of our knowledge about eating disorders derives from adolescent and young adult samples; knowledge regarding disordered eating in middle and later adulthood is limited. We examined the associations among known predictors of eating disorders for younger adults in an age-diverse sample and within the context of psychological distress.…

Patrick, Julie Hicks; Stahl, Sarah T.; Sundaram, Murali

2011-01-01

275

Religion and Psychological Distress in Japan  

Science.gov (United States)

This study introduces data from a new random sample of Japanese adults. Findings show that reporting of distress symptoms are: (1. positively associated with a religious coping index (i.e., beliefs that religion or supernatural beings provide comfort, support or protection), (2. associated in different directions with ownership of different…

Roemer, Michael K.

2010-01-01

276

Differences Between Experienced and Anticipatory Distress.  

Science.gov (United States)

Examined differences between distress ratings of anticipated and experienced life events in 168 college students. Found gender differences and significant differences between perceived and experienced aversion across events predicting symptoms of stress, depression, anxiety, and somatic discomfort in occupational, social and familial situations.…

Sowa, Claudia J.; Barsanti, Anne, N.

1986-01-01

277

Happiness and Death Distress: Two Separate Factors  

Science.gov (United States)

The aim of the present study was to explore the relationship between happiness and death distress (death anxiety, death depression, and death obsession) in 275 volunteer Kuwaiti undergraduates. They responded to the Oxford Happiness Inventory, the Death Anxiety Scale, the Arabic Scale of Death Anxiety, the Death Depression Scale-Revised, and the…

Abdel-Khalek, Ahmed M.

2005-01-01

278

Investigation of mechanical properties of pavement through electromagnetic techniques  

Science.gov (United States)

Ground-penetrating radar (GPR) is considered as one of the most flexible geophysical tools that can be effectively and efficiently used in many different applications. In the field of pavement engineering, GPR can cover a wide range of uses, spanning from physical to geometrical inspections of pavements. Traditionally, such inferred information are integrated with mechanical measurements from other traditional (e.g. plate bearing test) or non-destructive (e.g. falling weight deflectometer) techniques, thereby resulting, respectively, in time-consuming and low-significant measurements, or in a high use of technological resources. In this regard, the new challenge of retrieving mechanical properties of road pavements and materials from electromagnetic measurements could represent a further step towards a greater saving of economic resources. As far as concerns unpaved and bound layers it is well-known that strength and deformation properties are mostly affected, respectively, by inter-particle friction and cohesion of soil particles and aggregates, and by bitumen adhesion, whose variability is expressed by the Young modulus of elasticity. In that respect, by assuming a relationship between electromagnetic response (e.g. signal amplitudes) and bulk density of materials, a reasonable correlation between mechanical and electric properties of substructure is therefore expected. In such framework, a pulse GPR system with ground-coupled antennae, 600 MHz and 1600 MHz centre frequencies was used over a 4-m×30-m test site composed by a flexible pavement structure. The horizontal sampling resolution amounted to 2.4×10-2 m. A square regular grid mesh of 836 nodes with a 0.40-m spacing between the GPR acquisition tracks was surveyed. Accordingly, a light falling weight deflectometer (LFWD) was used for measuring the elastic modulus of pavement at each node. The setup of such instrument consisted of a 10-kg falling mass and a 100-mm loading plate so that the influence domain of the elasticity measure could be comparable to that of the radar signal. Good agreement were found between high Young modulus values and repaved zones, whereas damaged areas were characterized by lower values of E. Tomographic maps of amplitudes along the z axis were extracted up to a depth of z

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

2014-05-01

279

Banking distress in MENA countries and the role of mergers as a strategic policy to resolve distress  

OpenAIRE

This paper studies banking distress in MENA countries and considers the extent to which mergers are used as a solution for resolving individual banking distress. We use a two-level nested logit model to model the interdependence between merger decisions and the distressed state of banks. Both bank-specific variables and macroeconomic variables are deployed to predict banking distress. In line with other recent papers, we challenge the view that specific bank indicators such as CAMEL category ...

Sahut, Jean-michel; Mili, Mehdi

2011-01-01

280

Effects of reclaimed asphalt pavement on indirect tensile strength test of conditioned foamed asphalt mix  

International Nuclear Information System (INIS)

This paper presents the results of Indirect Tensile Strength (ITS) Test for samples prepared with reclaimed asphalt pavement (RAP). Samples were conditioned in water at 25°C for 24 hours prior to testing. Results show that recycled aggregate from reclaimed asphalt pavement performs as well as virgin aggregate.

281

AN ASSESSMENT OF THE OPERATIONAL LIFE OF CONCRETE AIRFIELD PAVEMENTS ON THE BASIS OF RELIABILITY THEORY  

Directory of Open Access Journals (Sweden)

Full Text Available The mathematical model of development and accumulation of defects of air-field pavements obtained with the use of the principal dependences of relia-bility theory is proposed. This model is implemented in the method of assessment of an operational life of concrete airfield pavements.

Yu. M. Borisov

2010-02-01

282

Permeable Pavement Monitoring at the Edison Environmental Center Demonstration Site - presentation  

Science.gov (United States)

The EPA?s Urban Watershed Management Branch has been monitoring an instrumented 110-space pervious pavement parking lot. The lot is used by EPA personnel and visitors to the Edison Environmental Center. The design includes 28-space rows of three permeable pavement types: asphal...

283

Permeable pavement monitoring at the EPA's Edison Environmental Center demonstration site  

Science.gov (United States)

There are few detailed studies of full-scale, replicated, actively-used pervious pavement systems. Practitioners need additional studies of pervious pavement systems in its intended application (parking lot, roadway, etc.) during a range of climatic events, daily usage conditions...

284

Quantifying Evaporation and Evaluating Runoff Estimation Methods in a Permeable Pavement System  

Science.gov (United States)

The U.S. Environmental Protection Agency constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable pavement in the parking lanes which were designed to receive run-on from the impervious hot-mix asphalt driving lanes. Twelve lined permeable pavement sec...

285

The Edison Environmental Center Permeable Pavement Site: Initial Results from a Stormwater Control Designed for Monitoring  

Science.gov (United States)

There are few detailed studies of full-scale, replicated, actively-used permeable pavement systems. Practitioners need additional studies of permeable pavement systems in its intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage conditio...

286

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

Science.gov (United States)

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 rage of 0.60 to 0.87 were observed the DRC predictive equations. In addition, verification of those generalized equations was evaluated using different sets of asphalt pavement structures and pavement materials. The differences between calculated and predicted values were found to be within +/-20% for the maximum tensile strain and +/-30% for the maximum compressive strain in the asphalt layer.

Ahsanuzzaman, Md

287

Technical development of cost-efficient installation of power distribution cables under pavements. Haiden chichuka ni okeru doboku kensetsu gorika gijutsu no kaihatsu  

Energy Technology Data Exchange (ETDEWEB)

Various latest technical developments were surveyed for the cost-effective installation of power distribution cables under pavements, and their applicabilities were demonstrated with the evaluation of their cost-reduction effects. Cables in conventional vinyl protection tubes could be buried only 30cm under pavements, and in such case, the cost was reduced to 51% of those of conventional methods. As the results of soil tests, excavated soil over 80% was reusable through coarse screening. Underground radar technique to explore buried pipes from the surface was detectable several pipes buried 1.5-2.0m underground, although some problems in precision were found. The improvement of reinforced concrete man-hole structures to minimize the volume of excavated soil indicated the cost reduction of nearly 20%. The application of these techniques to the installation of cables was expected to ultimately halve the total civil engineering cost. 21 refs., 130 figs., 46 tabs.

Kokusho, Koji; Kataoka, Tetsuyuki; Tanaka, Yasuyuki; Yoshida, Yasuo; Ikemi, Motoyoshi; Suzuki, Koichi; Kitano, Koichi; Kobayashi, Seiichi; Kanazu, Tsutomu; Komada, Hiroya.

1987-12-01

288

Psychological distress among women with newly diagnosed breast cancer  

DEFF Research Database (Denmark)

PURPOSE: Psychological distress is common in the cancer continuum. Our objectives were to determine the prevalence of distress and to investigate the related problems and the characteristics of women with breast cancer who experienced psychological distress at the time of diagnosis. METHODS: We used cross-sectional data from a questionnaire study. Women with newly diagnosed breast cancer were consecutively invited to respond before breast surgery. Between October 2008 and October 2009, a total of 357 responded out of 426 (84%) invited. Among these, 343 patients completed the 'distress thermometer' to measure psychological distress and the accompanying 'problem list' to identify related problems. Logistic regression models with 95% confidence intervals were used to estimate the associations between psychological distress, age, social support and domains on the problem list. RESULTS: With a cut-off of 3 on the distress thermometer, 77% of women with breast cancer reported distress, whereas when the cut-off was 7, 43% were distressed. The mean distress score was 5.4 (SD, 3.1). The most frequently reported problems were worry (77%) and nervousness (71%). Distress was significantly associated with the total score and three domains on the problem list. Younger women (

Mertz, Birgitte; Bistrup, Pernille Envold

2012-01-01

289

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

Science.gov (United States)

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

Yoshida, Nobuyuki; Sugisako, Yasunari

290

The interaction between concrete pavement and corrosion-induced copper runoff from buildings.  

Science.gov (United States)

Changes in chemical speciation of copper and the capacity of concrete pavement to retain copper in runoff water from external buildings have been investigated at urban field conditions, and in parallel laboratory experiments simulating outdoor scenarios. The research study showed the concrete surface to form a copper rich surface layer ( approximately 50 microm thick) upon exposure, and a high capacity to significantly reduce the bioavailable fraction of released copper (20-95%). The retention capacity of copper varied between 5 and 20% during single runoff events in the laboratory, and between 10 and 40% of the total copper release during single natural runoff events. The capacity to retain and reduce the bioavailable fraction of non-retained copper increased with increasing wetness of the concrete surfaces, increasing pH of the runoff water and decreasing flow rates. Bioassay testing with bacterial and yeast bioreporters showed the bioavailable fraction of non-retained copper to be significantly lower than the total copper concentration in the runoff water, between 22 and 40% for bacteria and between 8 and 31% for yeast. The application of generated data to simulate a fictive outdoor scenario, suggests a significant reduction of bioavailable and total copper to background values during environmental entry as a result of dilution, and the interaction with solid surfaces, organic matter and complexing agents already in the drainage system. PMID:17636419

Bahar, B; Herting, G; Wallinder, I Odnevall; Hakkila, K; Leygraf, C; Virta, M

2008-05-01

291

Potential for localized groundwater contamination in a porous pavement parking lot setting in Rhode Island  

Science.gov (United States)

The control of polluted surface runoff and the assessment of possible impacts on groundwater is a concern at the local and regional scale. On this background, a study investigates possible impacts of organic and inorganic pollutants (including bacteria) originating from a permeable asphalt parking lot on the water quality immediately beneath it. The functioning of the permeable pavement, including clogging and restricted vertical percolation, was also evaluated. Four nested sample ports (shallow and deep) were installed below low- and high-traffic areas, including one port outside the parking lot. At least initially there was a good hydraulic connection between the parking surface and the shallow sample ports. The presence of a geotextile layer at the base of the parking lot structure, however, was identified in lab tests as one factor restricting vertical percolation to the deeper ports. Clogging of the permeable surface was most pronounced in heavy traffic areas and below snow pile storage areas. Corroborated by high electric conductivity and chloride measurements, sand brought in by cars during winter was the principal cause for clogging. No bacteria or BOD were found in percolating water. Polycyclic aromatic hydrocarbons (PAH) were present at concentrations near minimum detection limit. Nutrients (nitrate and phosphate) were being leached into the ground via the permeable parking lot surface at annual flux rates of 0.45 0.84 g/m2/year. A multi-species tracer test demonstrated a retention capacity of the permeable parking lot structure of >90% for metals and 27% for nutrients, respectively.

Boving, Thomas B.; Stolt, Mark H.; Augenstern, Janelle; Brosnan, Brian

2008-08-01

292

Marital functioning, chronic pain, and psychological distress  

OpenAIRE

This study examined whether marital functioning variables related uniquely to psychological distress and diagnoses of depressive disorder independent of pain severity and physical disability. Participants were 110 chronic musculoskeletal pain patients. Hierarchical regression results showed that marital variables (i.e. marital satisfaction, negative spouse responses to pain) contributed significantly to depressive and anxiety symptoms over and above the effects of pain severity and physical d...

Cano, Annmarie; Gillis, Mazy; Heinz, Wanda; Geisser, Michael; Foran, Heather

2004-01-01

293

Negotiating with Labor under Financial Distress  

OpenAIRE

We analyze how firms renegotiate labor contracts to extract concessions from labor. While anecdotal evidence suggests that firms tend to renegotiate wages downward in times of financial distress, there is no empirical evidence that documents such renegotiation, its determinants, and its magnitude. This article attempts to fill this gap. Using a unique data set of airlines, which includes detailed information on wages and pension plans, we document an empirical link between airline financial d...

Benmelech, Efraim; Bergman, Nittai; Enriquez, Ricardo J.

2012-01-01

294

Financial distress model prediction using SVM +  

OpenAIRE

Financial distress prediction is of great importance to all stakeholders in order to enable better decision-making in evaluating firms. In recent years, the rate of bankruptcy has risen and it is becoming harder to estimate as companies become more complex and the asymmetric information between banks and firms increases. Although a great variety of techniques have been applied along the years, no comprehensive method incorporating an holistic perspective had hitherto b...

Ribeiro, Bernardete; Silva, C.; Vieira, Armando; Gaspar-cunha, A.; Neves, Joa?o

2010-01-01

295

Acute Respiratory Distress Due to Methane Inhalation  

OpenAIRE

Inhalation of toxic gases can lead to pneumonitis. It has been known that methane gas intoxication causes loss of consciousness or asphyxia. There is, however, a paucity of information about acute pulmonary toxicity from methane gas inhalation. A 21-year-old man was presented with respiratory distress after an accidental exposure to methane gas for one minute. He came in with a drowsy mentality and hypoxemia. Mechanical ventilation was applied immediately. The patient's symptoms and chest rad...

Jo, Jun Yeon; Kwon, Yong Sik; Lee, Jin Wook; Park, Jae Seok; Rho, Byung Hak; Choi, Won-il

2013-01-01

296

Progressive respiratory distress due to neck mass  

OpenAIRE

The present report describes the case of an 80-year-old woman who presented at the emergency department with progressive respiratory distress caused by a massive anterior neck mass with tracheal deviation and compression. A CT scan showed diffuse enlargement of the thyroid gland. The patient underwent a left-sided hemithyroidectomy. Pathology unexpectedly revealed a primary thyroid lymphoma. Treatment with prednisone and vincristine was initiated to reduce tumour size and preserve the airway,...

La Parra, Raquel F. D.; Kroeze, Jan; Die, Jos; Mulder, Dries; Zanten, Arthur; Tjan, David H.

2009-01-01

297

Asphaltic concrete overlays of rigid and flexible pavements  

Science.gov (United States)

The development of a mechanistic approach to overlay thickness selection is described. The procedure utilizes a deflection analysis to determine pavement rehabilitation needs. Design guides for selecting the overlay thickness are presented. Tolerable deflection-traffic load relationships and the deflection attenuation properties of asphaltic concrete were developed, representing the subgrade support conditions and properties of materials used in Louisiana. All deflection measurements on asphaltic concrete were corrected for the effect of temperature. Deflection measurements taken before and after overlay were also adjusted to minimize the effects of seasonal subgrade moisture variation.

Kinchen, R. W.; Temple, W. H.

1980-10-01

298

Psychosocial distress and periodontitis in adolescents  

DEFF Research Database (Denmark)

Periodontitis is an inflammatory disease associated with predominantly gram negative biofilms and characterized by the progressive destruction of the supporting tissues of the teeth. Some studies conducted among adults have found a significant association between periodontitis and dimensions of psychosocial distress and it is unclear whether this association can be found among younger subjects in which destruction of periodontal tissues as a result of periodontitis are less severe. Purpose: The main aim of this study was to assess whether adolescents with periodontitis presented with higher scores for non-psychotic psychosocial disorders than control subjects without periodontitis. Materials and Methods: We used a case control study (n=160) nested in a well-defined adolescent population (n=9,163) and the 28-item Spanish version of the General Health Questionnaire. The inclusion criterion for being a case was clinical attachment level ? 3 mm in at least two teeth. Multiple logistic regression analyses were used to assess the association between periodontitis and psychosocial distress. Results: The response rate was high and 94% of the participants answered all the items of the questionnaire. Similarly, the internal consistency of the instrument was high (Cronbach’s ? = 0.91). The results of multiple logistic regression analyses, adjusted for age and gender, suggested an association between case status and higher total scoring for psychosocial distress (OR=1.69). Among the four subdomains of General Health Questionnaire, the dimensions ‘somatic symptoms’ and ‘severe depression’ appeared positively associated with periodontal case status though not significantly.

Lopez, Rodrigo; Ramírez, Valeria

2012-01-01

299

Estimation of carrying capacity of slag and gravel forest road pavements  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of the study was to estimate the carrying capacity of forest roads with slag and gravel pavements. Deformation module and elastic deflection were used as characteristic parameters of road carrying capacity. There were 9 tested sections divided into set groups. All investigated sections were measured using VSS plate (29 measurements and deflectometer (53 measurements. Averaged results of the measurements of specific pavements were introduced in the analysis. The present study proved that the carrying capacity of slag and gravel pavements defined according to mean module ME is insufficient. The largest (122.87 MPa mean deformation module was detained for gravel pavement. Two slag pavements with significant constructional differences had very similar values of deformation modules 98.26 and 94.84 MPa. Taking maximum deformation modules ME into consideration, slag, gravel and gravel-broken-stone pavements comply with the requirements for low traffic intensity (ME=130–200 MPa. Only two-ply gravel pavements (about 25 cm thick have the mean carrying capacity complying with the requirements of low traffic intensity.

Grzegorz Trzcinski

2006-06-01

300

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

Directory of Open Access Journals (Sweden)

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

Gloria Inés Beltran

2014-07-01

301

Continuous highway pavements deflection measurements using a rolling dynamic deflectometer (RDD)  

Science.gov (United States)

Nondestructive testing of pavements plays an important role int he management of pavement infrastructure. A new technique for continuous profiling of pavements is under development. This technique involves the Rolling Dynamic Deflectometer (RDD). The RDD is a large truck on which a servo-hydraulic vibrator is mounted. The vibrator is used to apply large vertical dynamic loads to the pavement. The resulting dynamic displacements are sensed with rolling sensor. A description of the RDD and procedures used to analyze RDD data are discussed herein. The results of continuous RDD profiling of rigid pavements are presented. These results show that continuous stiffness profiles of displacement per given load of origin pavements can be used to characterize: 1) the pavement stiffness and its longitudinal variation; 2) the location of transverse cracks and joints; 3) the efficiency of transverse cracks and joints; 4) the efficiency of longitudinal joints; and 5) the lateral variation in average mid-span stiffness. Two significant benefits of continuous RDD profiles which are clearly shown are: 1) softer versus stiffer areas are clearly delineated and 2) the variation in joint efficiency is readily identified.

Bay, James A.; Stokoe, Kenneth H., II; Hudson, W. R.

1996-11-01

302

Optimal Maintenance Works for the Aborshada Road in the Western Region of Libya  

Science.gov (United States)

In this research, the condition of a road pavement was investigated for the Aborshada Road in the Gharian region of Libya to determine the optimal maintenance works. Previously, a simple engineering judgment was the only procedure followed by the Gharian municipal engineers for evaluating pavements and prioritizing maintenance. The surface condition of the Aborshada Road pavement was investigated using "the Pavement Condition Index (PCI)" visual technique. The pavement was inspected to survey the different distresses in each sample unit. Ninteen pavement distresses were classified according to the PCI standards (PCI for roads and parking lots became an ASTM standard in 2007 (D6433-07)). It was necessary to know the most common distresses of the Aborshada Road to provide assistance for the decision maker in his evaluation of the pavement and the optimum repair method to be selected. This study reveals the actual performance of the pavements and suggests the research required for dealing with the pavement maintenance problem in Libya, especially in the western region. The best maintenance alternative for Aborshada Road was Case No. 3 (Potholes, Long. & Trans. Cracking and Alligator Crack Maintenance). Also, the most common pavement distresses on the Aborshada Road were Distress Nos. 1, 3, 6, 7, 10 and 13 according to the ASTM - D6433-07 classification

Youssef, Medhat Abdelrahman; Elbasher, Abdelbary Altayb

2014-09-01

303

A System for Road Pavement Composite Material Deformation  

Directory of Open Access Journals (Sweden)

Full Text Available

For a comprehensive experimental evaluation of the material quality, forecast of the properties and parameter change of the bituminous material was made at the time under the impact of external factors, they are subjected to the necessary tests. In the article the automated set Tomsk-Asphalt-Test for determining the elastic modulus of the specimens made of bituminous materials was used in road pavements, maximally close to natural conditions of operation of highways of the Siberian region inRussiaare described. The automated set contains: electromechanical, climate, electronic, PC and software subsystem. The operation principle is a short-time deformation of the asphalt specimens; measurement of physical values: the stress, strain, variation of the size line and temperature of the asphalt pavement material test specimen, converting the measured values into electrical signals, their program processing and visualization. The control of testing and viewing results of measurements is carried out in accordance with the menu software subsystem. The results of calculations: the maximum values of vertical load the difference between the maximum horizontal deformation value and the value measured last after specimen of asphalt material loading for each test cycle, the sum of the differences of the horizontal deformation values of the two sensors and modulus of elasticity.

2012-12-01

304

Pavement deflection vehicle weighing method with embedded piezoelectric sensor  

Science.gov (United States)

In weigh-in-motion (WIM) system, the gross weight or the axle weight of the passing vehicle can be measured dynamically by the sensors installed in or on the pavement. One of the WIM sensors is piezoelectric sensor. Although piezoelectric sensor has limited measurement accuracy, it is widely deployed for its low cost and easy installation. To use the piezoelectric sensor, several factors have to be considered for the WIM site itself to ensure the vehicle passing over the sensor with a relative stable state. In addition, the piezoelectric sensor is seldom used for low speed measurement because of the piezoelectric material's performance. Traditional measurement method just uses the interactions between the sensor and the vehicle's tires that make the measurement inaccurate because the sensor cannot cover the whole tire patch along the driving direction. In this paper, the pavement deflection by the vehicle under measurement is introduced. New weighing method is developed for embedded piezoelectric sensors. Field tests are performed and the measurement errors are calculated based on the static weights measured from a static scale. Comparing to the traditional method, the proposed method is proved to have a higher accuracy and require less from installation site and vehicles under measurement. Furthermore, the method shows a better performance at low vehicle speed.

Guo, Lianhe; Chen, Xuemin; Yu, Jingyan; Tang, Yumei; Liu, Richard; Rogers, Richard; Leidy, Josef; Claros, Geman

2005-05-01

305

Finite Element Investigation of the Deterioration of Doweled Rigid Pavements  

CERN Document Server

The purpose of this study is to describe the failure of concrete around dowel bars in jointed rigid pavements, and the resulting effect on the pavement performance. In fact, under repetitive vehicle loading, concrete in contact with the dowel bar deteriorates, particularly at the joint face. The degradation of concrete around the dowel negatively affects the latter's performance in terms of transferring wheel loads through vertical shear action. In this context, a nonlinear 3D Finite Element analysis was performed using the commercial FE code Abaqus (v-6.11). The FE model was validated with classical analytical solutions of shear and moment along the dowel. A concrete damaged plasticity model was used for the PCC slab to model the degradation of concrete matrix around the dowels under incremental loading. Results obtained show, among other things, that the degradation of concrete matrix around the dowel was found to initiate at the face of the joint and propagate towards the interior of the dowel. Also, resul...

Ghauch, Ziad G

2011-01-01

306

Assessment of Distress Associated to Psychopathology in Children and Adolescents  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this paper was to study the distress associated to psychopathology in children and adolescents. The sample included 330 children aged 8 to 17 years attending outpatient mental health services of the public network in Barcelona(Spain assessed using a structured diagnostic interview. A substantial part of children brought to treatment suffered distress associated to internalizing and externalizing psychological symptoms. Psychological distress was most frequent among girls and among adolescents, and was more frequently reported by children and adolescents than by their parents. It was also a marker of perception of need of psychological help, and it was significantly related to diagnosis, subthreshold conditions and functional impairment. Individual symptoms of depression, dysthymia, generalized anxiety disorder and oppositional defiant disorder were most associated with psychological distress. Given the potential importance of subjective distress as well as impairment for the identification and definition of psychopathology and planning of treatment, diagnostic assessment should include questions related to distress.

Wendy Reich

2009-04-01

307

Psychological and physical distress of cancer patients during radiotherapy  

CERN Document Server

Purpose: patients undergoing radiotherapy have physical and psychological symptoms related to the underlying disease and the treatment. In order to give the best possible support to the patients, more knowledge about the amount and the changing of distress in the course of radiotherapy is of essentially importance. Methods: The distress was measured in a consecutive sample of cancer patients (n=82) undergoing radiotherapy. Each patient was given the EORTC-QLQ-C30, the HADS and a special questionnaire which ascertain radiotherapy-specific items before starting the radiotherapy, at the onset of radiotherapy, in the third week of radiotherapy and 3 weeks after the end of radiotherapy. Results: within the first week of treatment the psychological distress of the patients is increasing; 98.8 % of the patients are 'moderate distressed', 46 % 'severe distressed'. General physical symptoms seem not to be affected by the radiotherapy, there is no changing. The distress caused by the organization of the radiotherapy is...

König, A

2001-01-01

308

Long-term salt marsh recovery and pavement persistence at {sup M}etula' spill sites  

Energy Technology Data Exchange (ETDEWEB)

Three coastal sites oiled from the 1974 'Metula' oil spill in the Strait of Magellan were revisited in May 1998 to document oiling conditions 23.5 years after the spill. The sites revisited are in the Punta Espora area. Two are salt marshes and the third, an inter-tidal asphalt pavement. It was found that the marshes were still oil covered and bare of vegetation in most sections, although the tilling conducted in 1993 resulted in substantial increases in the number of plants that were able to recolonize. Application of fertilizer without tilling of the surface of the oil had no effect. By 1998 the oil, although still present, was weathered to a rubbery consistency. The large, 550 m. long asphalt pavement that had formed on the mixed-sediment beach remained, and showed relatively little change. Chemical analysis of the asphalt indicated extremely high degradation, including even some of the highly biodegradation-resistant biomarker compounds. The experimental treatment plots that were tilled in 1993 showed the highest level of weathered oil, and the highest degree of plant recolonization, suggesting that recolonization of the marshes could have been accelerated had tilling been conducted on these sites soon after the spill. 15 refs., 5 tabs., 6 figs.

Owens, E. H. [Polaris Applied Sciences, Bainbridge Island, WA (United States); Sergy, G. A. [Environment Canada, Edmonton, AB (Canada); Guzman, M. L. [Instituto de Fomento Pesquero, Punta Arenas (Chile); Wang, Z. [Environment Canada. Ottawa, ON (Canada); Baker, J. [Ruyton-XI-Towns (United Kingdom)

1999-07-01

309

Study of Sand Characteristics as Bearing and Filler in Joint of Inter-locking Concrete Block Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available The use of interlocking concrete block pavement as a road surface has increased in the road constructionrecently. This study was conducted to envisage the problems occur particularly for the bedding and joint filling sand of the interlocking concrete block pavement. Moreover, the effect of the moisture on the bedding sandwas also studied. Two type of additives namely as palm oil fly ash (POFA and silica fume, which carry thepozzolanic behaviour, were mixed with joint filling sand in order to improve its quality. These materials areindustrial waste compound which can be easily found in Malaysia. Two types of permeability experiments,the constant and falling head tests were conducted to evaluate the permeability of the joint filling sands withthe percentage additives used of 2%, 4%, 6%, 8% and 10%. A physical model was developed to investigatethe degree of compaction and water absorption via sand in joints. Water absorption test was also conductedonto the model with the addition of additives of 0%, 5% and 10% with the joint filling sand for 5 and 10days. Study shown that the incorporation of additives reduced the permeability of joint filling sand withthe optimum values obtained for both POFA and silica fume mixtures both were at 2% respectively.

Rosli Hainin

2009-09-01

310

Assessment of Distress Associated to Psychopathology in Children and Adolescents  

OpenAIRE

The aim of this paper was to study the distress associated to psychopathology in children and adolescents. The sample included 330 children aged 8 to 17 years attending outpatient mental health services of the public network in Barcelona(Spain) assessed using a structured diagnostic interview. A substantial part of children brought to treatment suffered distress associated to internalizing and externalizing psychological symptoms. Psychological distress was most frequent among girls and among...

Wendy Reich; Lourdes Ezpeleta; Roser Granero

2009-01-01

311

Epidemiologia do distress psicológico: estudo transversal de base populacional  

OpenAIRE

OBJETIVO: Determinar a prevalência e a distribuição de distress na esfera psicológica na população urbana adulta. MÉTODOS: Foram estudadas 3.942 pessoas maiores de 20 anos, do município de Pelotas, RS. Distress foi definido por meio de um indicador de bem-estar, a Escala de Faces, e através da autopercepção de nervosismo. O teste do qui-quadrado foi usado para testar associação com características sociodemográficas. RESULTADOS: A prevalência de distress psicológico foi de 14%...

Sparrenberger Felipe; Santos Iná dos; Lima Rosângela da Costa

2003-01-01

312

Perception of Financial distress and Customers’ Attitude toward Banking  

OpenAIRE

This study examined the influence of perceived financial distress and customers’ attitude towards banking in Nigeria. Two hundred and one bank customers made up of 144 males and 57 females drawn from 27 banks in Lagos participated in the study. The result of the study showed that perceived financial distress and bank account customer had significant main effect on attitude towards banking. The study concluded that perceived financial distress has significant negative influence on attitude t...

Sunday Samson Babalola

2009-01-01

313

Financial Distress Prediction in Emerging Market: Empirical Evidences from Iran  

OpenAIRE

In this article the ability of financial ratios for prediction of financial distress of the listed companies in Tehran Stock Exchange (TES) was investigated. For this reason, the multiple regression models were used and a model was presented for prediction of financial distress in listed companies in TES. The assessment of the model was done by utilizing the data of two groups. The first group contained 30 companies which don't have any financial distress, and the second group, similarly, con...

Mahdi Salehi; Bizhan Abedini

2009-01-01

314

Financial Distress and Idiosyncratic Volatility:An Empirical Investigation  

OpenAIRE

We address the twin puzzles of anomalously low returns for high idiosyncratic volatility and high distress risk stocks, documented by Ang, Hodrick, Xing and Zhang (2006) and Campbell, Hilscher and Szilagyi (2005), respectively. We accomplish two objectives in this study. First, we investigate the link between idiosyncratic volatility and distress risk and find that the idiosyncratic volatility effect exists only conditionally on high distress risk. Second, using a corrected single-beta CAPM m...

Chen, Jing; Chollete, Lora?n

2006-01-01

315

Resolving financial distress in the Netherlands, a case study approach  

OpenAIRE

In this thesis four firms in financial distress have been studied. The methods the Dutch Bankruptcy System offers to firms to resolve their financial problemns have been described, and theories addressing the efficiency of rules and behavior of participants in firms in financial distress have been discussed. These theoretical ideas have been contrasted with the actual behavior of the participants with the four firms in financial distress. In this chapter the aswwers to the research questions ...

Couwenberg, Oscar

1997-01-01

316

Proportioning of Steel Fibre Reinforced Concrete Mixes for Pavement Construction and Their Impact on Environment and Cost  

Directory of Open Access Journals (Sweden)

Full Text Available Steel fibre reinforced concrete (SFRC is a construction material investigated for more than 40 years including for pavement applications. A number of studies have demonstrated the technical merits of SFRC pavements over conventional concrete pavements; however little work has been carried out on the environmental and economical impact of SFRC during the pavement’s life cycle. Therefore, extended research was undertaken within the framework of the EU funded project “EcoLanes” to estimate the environmental and economical loadings of SFRC pavements. The innovative concept of the project is the use of recycled steel tyre-cord wire as concrete fibre reinforcement, which provides additional environmental benefits for tyre recycling over landfilling. Within the project framework a demonstration of a steel-fibre-reinforced roller-compacted concrete (SFR-RCC pavement was constructed in a rural area in Cyprus. In order to assess the economical and environmental picture of the demonstration pavement, life cycle cost analysis (LCCA and life cycle assessment (LCA studies were undertaken, which also compared the under study pavement design with four conventional alternatives. The main output of the studies is that SFR-RCC is more environmentally and economically sustainable than others. In addition, various concrete mix designs were investigated by considering parameters such as fibre type and dosage, cement type, and transportation distances to the construction site. Fibre dosage has been highlighted as a crucial factor compared with economical and environmental loadings in SFR-RCC pavement construction.

Stelios Kallis

2011-07-01

317

Reduction in mental distress among substance users receiving inpatient treatment  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Substance users being admitted to inpatient treatment experience a high level of mental distress. In this study we explored changes in mental distress during treatment. Methods Mental distress, as measured by the HSCL-10, was registered at admission and at discharge among 164 substance users in inpatient treatment in Northern Norway. Predictors of reduction in mental distress were examined utilizing hierarchical regression analysis. Results We found a significant reduction in mental distress in the sample, but the number of patients scoring above cut-off on the HSCL-10 at discharge was still much higher than in the general population. A more severe use of substances as measured by the AUDIT and the DUDIT, and being female, predicted a higher level of mental distress at admission to treatment as well as greater reduction in mental distress during treatment. Holding no education beyond 10 year compulsory school only predicted a reduction in mental distress. Conclusions The toxic and withdrawal effects of substances, level of education as well as gender, contributed to the differences in change in mental distress during treatment. Regression to the mean may in part explain some of the findings.

Friborg Oddgeir

2010-12-01

318

Development of a distress inventory for cancer: preliminary results.  

Directory of Open Access Journals (Sweden)

Full Text Available CONTEXT: Advances in cancer treatment have led to cure and prolongation of patients? lives; however associated psychosocial problems, including distress, can detrimentally affect patients? compliance with treatment and ultimately, their outcome. Symptom distress has been well addressed in many studies; however, psychological distress has only been quantified by using depression or anxiety scales/checklists or quality of life scales containing a distress sub scale/component or by the use of scales that are not psychological distress-specific. AIMS: The present study is an attempt to construct a psychological distress inventory for specific use with cancer patients. SETTINGS AND DESIGN: The standardisation sample consisted of 63 randomly selected patients with head and neck cancer who had undergone/ were undergoing curative treatment at the Regional Cancer Centre, Trivandrum. PATIENTS AND METHODS: The Distress Inventory for Cancer contained 57 positively and negatively toned items. An item analysis was conducted, followed by a factor analysis, thereby identifying the domains influencing distress. RESULTS: The final questionnaire contained 26 items subdivided into four domains viz. the personal, spiritual, physical, and the family domains, with each domain providing a sub score. The reliability coefficient (Cronbach?s alpha of the scale was found to be 0.85. CONCLUSIONS: These are the preliminary results of an ongoing study on global distress and tool development process. Reported here is the first step towards development of such tool.

Thomas B

2002-01-01

319

Muted neural response to distress among securely attached people.  

Science.gov (United States)

Neural processes that support individual differences in attachment security and affect regulation are currently unclear. Using electroencephalography, we examined whether securely attached individuals, compared with insecure individuals, would show a muted neural response to experimentally manipulated distress. Participants completed a reaction time task that elicits error commission and the error-related negativity (ERN)-a neural signal sensitive to error-related distress-both before and after a distressing insecurity threat. Despite similar pre-threat levels, secure participants showed a stable ERN, whereas insecure participants showed a post-threat increase in ERN amplitude. These results suggest a neural mechanism that allows securely attached people to regulate distress. PMID:23887815

Nash, Kyle; Prentice, Mike; Hirsh, Jacob; McGregor, Ian; Inzlicht, Michael

2014-08-01

320

Moral distress experienced by nurses: A quantitative literature review.  

Science.gov (United States)

Nurses are frequently confronted with ethical dilemmas in their nursing practice. As a consequence, nurses report experiencing moral distress. The aim of this review was to synthesize the available quantitative evidence in the literature on moral distress experienced by nurses. We appraised 19 articles published between January 1984 and December 2011. This review revealed that many nurses experience moral distress associated with difficult care situations and feel burnout, which can have an impact on their professional position. Further research is required to examine worksite strategies to support nurses in these situations and to develop coping strategies for dealing with moral distress. PMID:24091351

Oh, Younjae; Gastmans, Chris

2015-02-01

321

A Statistical Analysis to Predict Financial Distress  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study is to apply the statistical inference to identify if a firm is likely to become financially distressed in the short term. To do this, we decided to collect data from the firms’ financial statements. The analyses performed were based on a group of 45 financial ratios observed from a sample of 86 firms operating in Argentina. First, we used the principal component analysis to turn the information in the 45 original ratios into two new global variables named as ?Risk and ?Return. In this way, we can easily represent and compare in a graph the firms’ risk and return variations. By the computation of these new variables it is possible to quickly financially categorize a certain firm based on the risk the company has with regard to the nature of its business and the risk involved in the amount of debt it has taken in comparison to the profits that were generated during the last two fiscal years. Second, we performed a logistic regression analysis to estimate the probability that a firm becomes financially distressed in the short term. The model finally selected managed to successfully identify 85% of the companies from the sample and it explains 65% of the total sample variability. The model is represented by the following variables: 1 Current Debt Ratio, 2 Total Cost of Debt, 3 Operating Profit Margin, and 4 ?ROE. The outcomes from this study are two tools that were developed based on the statistical inference from which we can quickly asses the financial status of a firm based on its risks and return’s variation as well as to estimate the probability that a firm becomes financially distressed in the short term. There are different ways of taking these tools into practice such as: 1 to control and follow up the financial performance of a company, 2 to support the decision of lending money to a company, 3 to support the decision of investing money or the decision of merging with a company, 4 to support market analysis from a financial perspective, and 5 to support actions or decisions related to the financial assessment of a company that declares itself to be financially distressed.

Nicolas Emanuel Monti

2010-09-01

322

Acute respiratory distress caused by Neosartorya udagawae  

Directory of Open Access Journals (Sweden)

Full Text Available We describe the first reported case of acute respiratory distress syndrome (ARDS attributed to Neosartorya udagawae infection. This mold grew rapidly in cultures of multiple respiratory specimens from a previously healthy 43-year-old woman. Neosartorya spp. are a recently recognized cause of invasive disease in immunocompromised patients that can be mistaken for their sexual teleomorph, Aspergillus fumigatus. Because the cultures were sterile, phenotypic identification was not possible. DNA sequencing of ITS, calmodulin and ?-tubulin genes supported identification of Neosartorya udagawae. Our case is the first report of ARDS associated with Neosartorya sp. infection and defines a new clinical entity.

John J. Farrell

2014-10-01

323

The use of accelerometers in the pavement performance monitoring and analysis  

Science.gov (United States)

This study investigated the use of sensor technology to enhance the management of highway infrastructure. With the help of monitoring data, it is possible to assess the current analytical pavement analysis method, which is based on multi-layered elastic analysis, and, thus enhance the pavement design practices in use. Pavement response was measured using different sensors, installed at various depths. Most promising sensors for the continuous monitoring purposes were the accelerometers. The drawback of these sensors is that the measured quantity is acceleration, which must be converted to the deflection via mathematical integration. In this paper some issues related to the manipulation of accelerometer data is presented and discussed, in addition of the discussion of the calculated and measured pavement response.

Ryynänen, T.; Pellinen, T.; Belt, J.

2010-06-01

324

Theoretical analysis of piezoelectric energy harvesting from traffic induced deformation of pavements  

International Nuclear Information System (INIS)

The problem of energy harvesting using piezoelectric transducers for pavement system applications is formulated with a focus on moving vehicle excitations. The pavement behavior is described by an infinite Bernoulli–Euler beam subjected to a moving line load and resting on a Winkler foundation. A closed-form dynamic response of the pavement is determined by a Fourier transform and the residue theorem. The voltage and power outputs of the piezoelectric harvester embedded in the pavements are then obtained by the direct piezoelectric effect. A comprehensive parametric study is conducted to show the effect of damping, the Winkler modulus, and the velocity of moving vehicles on the voltage and power output of the piezoelectric harvester. It is found that the output increases sharply when the velocity of the vehicle is close to the so-called critical velocity. (paper)

325

Integration and road tests of a self-sensing CNT concrete pavement system for traffic detection  

International Nuclear Information System (INIS)

In this paper, a self-sensing carbon nanotube (CNT) concrete pavement system for traffic detection is proposed and tested in a roadway. Pre-cast and cast-in-place self-sensing CNT concrete sensors were simultaneously integrated into a controlled pavement test section at the Minnesota Road Research Facility (MnROAD), USA. Road tests of the system were conducted by using an MnROAD five-axle semi-trailer tractor truck and a van, respectively, both in the winter and summer. Test results show that the proposed self-sensing pavement system can accurately detect the passing of different vehicles under different vehicular speeds and test environments. These findings indicate that the developed self-sensing CNT concrete pavement system can achieve real-time vehicle flow detection with a high detection rate and a low false-alarm rate. (paper)

326

Development of Knowledge-Based Expert System for Flexible Pavement Design  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, the knowledge-based expert system approach was used to design a programmer using shell expert system of KAPPA PC Version 2.4 that is object oriented and displaying higher graphic resolutions. The flexible pavement design based on the accumulation of knowledge from several experts, books and journals results in a modular approach. Normally, the process of flexible pavement design is done by experts. The process was computerized and apply artificial intelligent that is a new technology in providing a system that can design and give the suggestion for user to choices the best and economy of the thickness of pavement layers. The expert system was tested using several design calculation samples. From the test, the success is 100% for pavement design. The expert system has revealed satisfactorily findings in a faster layers design.

Deprizon

2009-01-01

327

Thermal stresses of asphalt pavement under dependence of material characteristics on reference temperature  

Science.gov (United States)

This thesis presents an analytical study of thermal stresses of asphalt pavement under dependence of material characteristics on reference temperature. In the analysis, flexible pavement is regarded as a multi-layered elastic half-space axisymmetrical system. Firstly, thermo-elastic theory is used to describe thermal stresses of a multi-layered system, while the temperature-dependent material characteristics are considered. Then Laplace transformation and Hankel transformation with respect to time and radial, respectively, are utilized for thermo-elastic equations of equilibrium. In addition, the transfer matrix method is applied to derive general solutions for the multi-layered problem. Finally, the resulting formulation is applied to calculate thermal stresses in the low temperature cracking problem of asphalt pavement. Thermal stress is calculated and compared with the case that material characteristics are supposed to be constant to show the remarkable impact of temperature-dependent material characteristics on thermal stresses of asphalt pavement.

Zhong, Yang; Geng, Litao

2009-03-01

328

Integration and road tests of a self-sensing CNT concrete pavement system for traffic detection  

Science.gov (United States)

In this paper, a self-sensing carbon nanotube (CNT) concrete pavement system for traffic detection is proposed and tested in a roadway. Pre-cast and cast-in-place self-sensing CNT concrete sensors were simultaneously integrated into a controlled pavement test section at the Minnesota Road Research Facility (MnROAD), USA. Road tests of the system were conducted by using an MnROAD five-axle semi-trailer tractor truck and a van, respectively, both in the winter and summer. Test results show that the proposed self-sensing pavement system can accurately detect the passing of different vehicles under different vehicular speeds and test environments. These findings indicate that the developed self-sensing CNT concrete pavement system can achieve real-time vehicle flow detection with a high detection rate and a low false-alarm rate.

Han, Baoguo; Zhang, Kun; Burnham, Tom; Kwon, Eil; Yu, Xun

2013-01-01

329

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

Directory of Open Access Journals (Sweden)

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

Kundan Meshram

2013-03-01

330

Permeable Pavement Research at NRMRL?s Urban Watershed Research Facility (Poster 2)  

Science.gov (United States)

Assess pollutant removal efficiency of porous pavement systems with regard to parking lot runoff. Bench-scale study will examine: Discharge volume Flow rate Total suspended solids (TSS) of influent vs. effluent Use of a geotextile permeable filter fabric...

331

Monitoring of the Permeable Pavement Demonstration Site at the Edison Environmental Center (Poster)  

Science.gov (United States)

This is a poster on the permeable pavement parking lot at the Edison Environmental Center. The monitoring scheme for the project is discussed in-depth with graphics explaining the instrumentation installed at the site. ...

332

The use of accelerometers in the pavement performance monitoring and analysis  

International Nuclear Information System (INIS)

This study investigated the use of sensor technology to enhance the management of highway infrastructure. With the help of monitoring data, it is possible to assess the current analytical pavement analysis method, which is based on multi-layered elastic analysis, and, thus enhance the pavement design practices in use. Pavement response was measured using different sensors, installed at various depths. Most promising sensors for the continuous monitoring purposes were the accelerometers. The drawback of these sensors is that the measured quantity is acceleration, which must be converted to the deflection via mathematical integration. In this paper some issues related to the manipulation of accelerometer data is presented and discussed, in addition of the discussion of the calculated and measured pavement response.

333

23 CFR 970.208 - Federal lands pavement management system (PMS).  

Science.gov (United States)

...HIGHWAYS NATIONAL PARK SERVICE MANAGEMENT SYSTEMS National Park Service Management Systems § 970.208 Federal lands pavement management system (PMS). In addition...depend on mileage, functional classes, volumes, loading,...

2010-04-01

334

A philosophical taxonomy of ethically significant moral distress.  

Science.gov (United States)

Moral distress is one of the core topics of clinical ethics. Although there is a large and growing empirical literature on the psychological aspects of moral distress, scholars, and empirical investigators of moral distress have recently called for greater conceptual clarity. To meet this recognized need, we provide a philosophical taxonomy of the categories of what we call ethically significant moral distress: the judgment that one is not able, to differing degrees, to act on one's moral knowledge about what one ought to do. We begin by unpacking the philosophical components of Andrew Jameton's original formulation from his landmark 1984 work and identify two key respects in which that formulation remains unclear: the origins of moral knowledge and impediments to acting on that moral knowledge. We then selectively review subsequent literature that shows that there is more than one concept of moral distress and that explores the origin of the values implicated in moral distress and impediments to acting on those values. This review sets the stage for identifying the elements of a philosophical taxonomy of ethically significant moral distress. The taxonomy uses these elements to create six categories of ethically significant moral distress: challenges to, threats to, and violations of professional integrity; and challenges to, threats to, and violations of individual integrity. We close with suggestions about how the proposed philosophical taxonomy of ethically significant moral distress sheds light on the concepts of moral residue and crescendo effect of moral distress and how the proposed taxonomy might usefully guide prevention of and future qualitative and quantitative empirical research on ethically significant moral distress. PMID:25503608

Thomas, Tessy A; McCullough, Laurence B

2015-02-01

335

Leachability of dissolved chromium in asphalt and concrete surfacing materials.  

Science.gov (United States)

Leachate metal pollutant concentrations produced from different asphalt and concrete pavement surfacing materials were measured under controlled laboratory conditions. The results showed that, in general, the concentrations of most metal pollutants were below the reporting limits. However, dissolved chromium was detected in leachate from concrete (but not asphalt) specimens and more strongly in the early-time leachate samples. As the leaching continued, the concentration of Cr decreased to below or close to the reporting limit. The source of the chromium in concrete pavement was found to be cement. The concentration of total Cr produced from leachate of different cement coming from different sources that was purchased from retail distributors ranged from 124 to 641mug/L. This result indicates that the potential leachability of dissolved Cr from concrete pavement materials can be reduced through source control. The results also showed that the leachability of dissolved Cr in hardened pavement materials was substantially reduced. For example, the concentration of dissolved Cr measured in actual highway runoff was found to be much lower than the Cr concentration produced from leachate of both open and dense graded concrete pavement specimens under controlled laboratory study. It was concluded that pavement materials are not the source of pollutants of concern in roadway runoff; rather most pollutants in roadway surface runoff are generated from other road-use or land-use sources, or from (wet or dry) atmospheric deposition. PMID:19604624

Kayhanian, Masoud; Vichare, Akshay; Green, Peter G; Harvey, John

2009-08-01

336

Rut Depth Prediction on Flexible Pavements - Calibration and Validation of Incremental-Recursive Models  

OpenAIRE

In later years the development of pavement design has gone towards more and more analytically based methods. Future design will probably be based on incremental deterioration models. The objective is to evaluate different types of rut depth prediction models for an incremental design process. Two different models were chosen for further studies: One model that calculates the plastic strain through the whole pavement, and one model that calculates a critical response. The models ...

Agardh, Sven

2005-01-01

337

The influence of recycled asphalt pavement on the fatigue performance of asphalt concrete base courses  

OpenAIRE

This paper presents the physical properties of Recycled Asphalt Pavement (RAP) and its influence on the mechanical performance of a binder course asphalt pavement mix. A series of binder course mixes were designed containing varying percentages of RAP. A mix made from only virgin material was selected as the control mix for the investigation. The effect of introducing RAP into the binder course mix was evaluated through a series of laboratory tests including the Marshall test, the indirect te...

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

2010-01-01

338

Mathematical failure-theory (MFT) methodology in pavement management system for rehabilitation and repair methods selection  

OpenAIRE

Pavement rehabilitation and repair methods selection is one of the key issues many road organizations and researchers have occupied. Not only road management cost but also road user’s cost and cost for inhabitants and community should be included in the life cycle cost in order to help infrastructure investment judgment. Thus in estimating life cycle cost, Pavement rehabilitation and repair methods selection is essential even if technological capabilities of evaluation are not sufficient. I...

Fereidoon Moghadas Nejad; Hasan Ziari; Ameri Mahmod

2009-01-01

339

Evaluation of test methods for estimating resilient modulus of modules of pavement geomaterials  

OpenAIRE

Resilient modulus is a key parameter required for the mechanistic empirical pavement design procedures currently being adopted around the world including the recently developed NCHRP 1- 37A design guide in the United States and the current South African Pavement Design Method(SAPDM). The determination of the resilient modulus requires sophisticated equipment and skilled personnel for laboratory and field testing. These requirements have contributed immensely to the proliferation of differe...

Anochie-boateng, J. K.; Paige-green, Philip; Mgangira, M. B.

2009-01-01

340

Lead and zinc removal with storage period in porous asphalt pavement  

Scientific Electronic Library Online (English)

Full Text Available Porous asphalt pavements have been used as an effective technique to overcome road runoff challenges, and to improve efficiency of rainwater utilisation in urban areas. Using porous asphalt pavements with reservoir storage and harvesting facilities is an important consideration for the future. This [...] study monitored changes in water quality indicators, such as pH, conductivity, and concentrations of lead and zinc, for water stored in porous asphalt pavement models with basalt-, limestone- and 'basalt+limestone'-filled reservoir structures. The research discusses findings over a 696-h storage period following artificial rainfall. Total lead and zinc concentrations were remarkably reduced throughout the initial flush, showing, on average, reductions of 90% and 80.5%, respectively. This pattern was consistent throughout the storage period, producing average reductions in lead and zinc of 99.98% and 79%, respectively, over 696 h. Conductivity and pH levels increased in all pavement models after the 696-h storage. The results obtained confirmed the potential of using porous asphalt pavements with reservoir structures to remove heavy metals from road runoff. This can be applied to future research on the removal mechanisms of porous asphalt pavements in relation to heavy metals in road runoff.

Yao, Zhao; Chen, Zhao.

2014-01-01

341

Fatigue Investigation of the Interface Shear Performance in Asphalt Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available This paper shows the interlayer fatigue performance evaluated by the Sapienza shear testing machine. The tests can be performed by placing double layer specimens in several inclinations, in order to reproduce a variety of expected ratios between the normal and the shear stress. The machine manages loads with any kind of waveform and is particularly able to simulate the stress trends expected in field in points located just outside the wheel path. In this experimentation, the machine applies a triangular waveform load computed by a linear elastic multilayer program at the depth of the first pavement interface. A fatigue law is estimated considering the number of repetitions that causes the interface failure. A linear regression in the log-log graph suitably fits the experimental results for the analyzed conditions of temperature and interface type.

Cristina Tozzo

2014-02-01

342

Performance of preformed compression sealers in transverse pavement joints  

Science.gov (United States)

Preformed compression sealers, 1-1/4 in. wide and installed in 5/8 in. wide transverse contraction joints in rigid pavements, were observed for up to 10 years. Many joints closed tighter than the 5/8 in. minimum design width. Results of force deflection and recovery tests performed on new sealer samples related to compression set occurring during field service, but not to infiltration. Force deflection and recovery properties of the sealers generally decreased after field aging. Preconditioning sealer samples at elevated (212 F) or reduced (14 and 20 F) temperatures produced changes in force deflection and recovery properties. A laboratory cycle test, which simulates joint infiltration, appeared to relate to field infiltration.

Bryden, J. E.; Lorini, R. A.

1980-03-01

343

Road Performance of Fiber Reinforced Asphalt Concrete Bridge Deck Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available As the problem of asphalt concrete bridge deck pavement is becoming more and more serious, how to improve its road performance has become the focus of the study. Considering fiber is widely used in road engineering, wheel tracking test, flexural test, immersion marshall test and freeze-thaw splitting test were carried out to study road performance of asphalt mixture with different fiber contents, analyzing the function mechanism of fiber reinforced asphalt concrete. The test results show that polyester fiber can improve high-temperature stability, low-temperature crack resistance property and water stability of asphalt concrete and road performance improves with the fiber content increasing in a certain range.

Xiu Liu

2013-01-01

344

Examining Victimization and Psychological Distress in Transgender College Students  

Science.gov (United States)

Treatment-seeking and non-treatment-seeking transgender college students were examined with regard to victimization and psychological distress. Findings showed that transgender college students had elevated rates of distress as compared with college students who identified as men or women. Results indicated that treatment-seeking and non-treatment…

Effrig, Jessica C.; Bieschke, Kathleen J.; Locke, Benjamin D.

2011-01-01

345

Custodial Grandmothers' Psychological Distress, Dysfunctional Parenting, and Grandchildren's Adjustment*?  

OpenAIRE

An adaptation of the Family Stress Model (FSM) with hypothesized linkages between family contextual factors, custodial grandmothers' psychological distress, parenting practices, and grandchildren's adjustment was tested with structural equation modeling. Interview data from 733 custodial grandmothers of grandchildren between ages 4-17 revealed that the effect of grandmothers' distress on grandchildren's adjustment was mediated by dysfunctional parenting, especially regarding externalizing pro...

Smith, Gregory C.; Palmieri, Patrick A.; Hancock, Gregory R.; Richardson, Rhonda A.

2008-01-01

346

Psychopathic Traits, Victim Distress and Aggression in Children  

Science.gov (United States)

Background: The relationship between psychopathic traits and aggression in children may be explained by their reduced sensitivity to signs of distress in others. Emotional cues such as fear and sadness function to make the perpetrator aware of the victim's distress and supposedly inhibit aggression. As children high in psychopathic traits show a…

van Baardewijk, Yoast; Stegge, Hedy; Bushman, Brad J.; Vermeiren, Robert

2009-01-01

347

Psychological distress and mortality in systolic heart failure  

DEFF Research Database (Denmark)

Depression, anxiety, and type D ("distressed") personality (tendency to experience negative emotions paired with social inhibition) have been associated with poor prognosis in coronary heart disease, but little is known about their role in chronic heart failure. Therefore, we investigated whether these indicators of psychological distress are associated with mortality in chronic heart failure.

Pelle, Aline J; Pedersen, Susanne S.

2010-01-01

348

Test of Microstructur Permeable Asphalt Pavement Used Domato Stone (Quarsite Dolomite As Course Agregate for Surface Layer of Road Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available The experiment works was dividing into two phases, for phase one was developed to investigate the properties of aggregates and straight asphalt qualities. The experiment work for phase two was developed to design the porous asphalt mix. In this phase Japan’s method and Binamarga’s method was used to define optimum asphalt content. In this phase, has result cantabro loss weight 77.10 for asphalt quality 3% and loss weight 9.70 for asphalt quality 5%. asphalt flow down, air void and density values. The experiment work for phase two was developed to investigate the qualities of porous asphalt. In this phase, wheel tracking machine test was used to investigate the dynamic stability of mixes.

Firdaus Chairuddin

2014-06-01

349

Acute respiratory distress in a silversmith  

Science.gov (United States)

A 25-year-old young male patient presented in casualty department with severe respiratory distress on the fourth day from onset of symptoms. The patient was nonsmoker and had no antecedent medical or drug history. Prior to admission, patient had dry cough and bilateral pleuritic chest pain for the last three days. He was in severe respiratory distress with use of accessory muscles of respiration. On examination, he had heart rate of 120 beats/min, blood pressure (BP) of 150/80, respiratory rate of 48-52/min and central cyanosis present. On systemic examination, reduced intensity of breath sounds with extensive rhonchi and crepitation was found in both lung fields, with other examination being within normal limits. On pulse oximetry, oxygen saturation was 28% on room air, which increased up to 36% with the help of 4 L oxygen via nasal prongs. PaO2/FiO2 ratio was 100. Chest X-ray analysis was suggestive of non-cardiac pulmonary edema in view of bilateral fluffy opacity without cardiomegaly. In view of 2/3 positive criteria, his provisional diagnosis was Acute Respiratory Distress Syndrome (ARDS). He required mechanical ventilatory support and was gradually weaned over a period of 10 days. The patient was treated with broad spectrum antibiotics and other supportive measures. On re-evaluation of history, we found that he was a goldsmith by occupation, smelting silver and gold for the past 8-10 years. On the day of onset of symptoms, while smelting silver he was exposed to golden yellow fumes for around 15 minutes, with the quantum of exposure more than any other day earlier. From previous experience and analysis of similar silver metals, he was able to tell us that the silver was adulterated with large amount of cadmium on that day than before. Serum level of cadmium was 2.9 ?g/L 6 days after initial exposure. At the time of discharge, he had residual opacities in the chest radiograph and resting oxygen saturation was 94% on room air. PMID:25006313

Parikh, Jignesh Mukeshkumar; Dhareshwar, Shashank; Sharma, Anand; Karanth, Raghuveer; Ramkumar, V. S.; Ramaiah, Indira

2014-01-01

350

Sharing, liking, commenting, and distressed? The pathway between Facebook interaction and psychological distress.  

Science.gov (United States)

Studies on the mental health implications of social media have generated mixed results. Drawing on a survey of college students (N=513), this research uses structural equation modeling to assess the relationship between Facebook interaction and psychological distress and two underlying mechanisms: communication overload and self-esteem. It is the first study, to our knowledge, that examines how communication overload mediates the mental health implications of social media. Frequent Facebook interaction is associated with greater distress directly and indirectly via a two-step pathway that increases communication overload and reduces self-esteem. The research sheds light on new directions for understanding psychological well-being in an increasingly mediated social world as users share, like, and comment more and more. PMID:23745614

Chen, Wenhong; Lee, Kye-Hyoung

2013-10-01

351

Experimental Analysis of Natural Gravel Covering as Cool Roofing and Cool Pavement  

Directory of Open Access Journals (Sweden)

Full Text Available Passive solutions for building energy efficiency represent an interesting research focus nowadays. In particular, natural materials are widely investigated for their potential intrinsic high thermal energy and environmental performance. In this view, natural stones represent a promising solution as building envelope covering and urban pavement. This paper concerns the experimental characterization of several low-cost and local gravel coverings for roofs and urban paving, properly selected for their natural high albedo characteristics. To this aim, the in-field albedo of gravel samples is measured with varying grain size. These in-field measurements are compared to in-lab measurements of solar reflectance and thermal emissivity. The analysis shows a significant variation of the albedo with varying grain size. Both in-lab and in-field measurements agree that the stones with the finest grain size, i.e., fine sand, have the best optic-thermal performance in terms of solar reflectance (62%. This feature results in the reduction of the surface temperature when exposed to solar radiation. Moreover, a natural mixed stone is compared to the high reflectance stone, demonstrating that the chosen stone presents an intrinsic “cool” behavior. Therefore, this natural, low-cost, durable and sustainable material could be successfully considered as a natural cool roof or cool paving solution.

Anna Laura Pisello

2014-07-01

352

Stresses, strains, and displacements in a poroelastic layered pavement model subject to a moving load  

International Nuclear Information System (INIS)

The response of a layered poroelastic halfspace to a progressing normally distributed load applied at the surface is evaluated for the case in which the constant velocity of the moving load is less than that of the elastic waves in each layer. It is assumed that a steady state exists with respect to the coordinate axes attached to a moving load. A three-dimensional problem for Biot's consolidated equations is then solved by taking Fourier transforms in the horizontal directions to evaluate stresses and displacements at any point in the medium. The analysis is illustrated by numerical examples using an algorithm based on one previously developed to calculate the response to a static load for axisymmetric poroelastic layers. To reduce the amount of computation, attention is restricted to a two-dimensional problem in which the load extends infinitely in the transverse direction. Results are presented for two and three-layered pavement models composed of concrete and gravel over a clay subbase responding to moving traffic, but the method is applicable to any number of layers. The effect of varying the velocity of the load and layer properties is observed

353

Moss cushions facilitate water and nutrient supply for plant species on bare limestone pavements  

DEFF Research Database (Denmark)

Dense moss cushions of different size are distributed across the bare limestone pavements on Øland, SE Sweden. Increasing cushion size is predicted to physically protect and improve performance and colonization by vascular plants. Therefore, we tested water balance, phosphorus supply, and species richness, and evaluated duration of plant activity during desiccation as a function of ground area, for a large collection of moss cushions. We found that lower evaporation and higher water storage contributed equally to extending the desiccation period with increasing cushion size. Evaporation rates declined by the -0.36 power of cushion diameter, and were not significantly different from -0.50 for the square root function previously predicted for the increasing thickness of the boundary layer, with greater linear dimensions for smooth flat objects at low wind velocities. Size dependence vanished under stagnant conditions. One moss species was added to the species pool for every nine-fold increase in cushion area. Vascular plants were absent from the smallest cushions, whereas one or two species, on average, appeared in 375- and 8,500-cm(2) cushions with water available for 6 and 10 days during desiccation. Phosphorus concentrations increased stepwise and four-fold from detritus to surface mosses and to vascular plants, and all three pools increased with cushion size. We conclude that cushion mosses and cushion size play a critical role in this resource-limited limestone environment by offering an oasis of improved water and nutrient supply to colonization and growth of plants.

Jensen, Kaj Sand; Hammer, Kathrine

2012-01-01

354

Predictors of mental distress among substance abusers receiving inpatient treatment  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Mental distress measured by the HSCL-10 is used as an indicator of psychiatric disorders in population studies, where a higher level of mental distress has been shown to be related to demographic factors such as living conditions and level of education. The first aim of the study was to explore whether mental distress could be a valuable concept in substance use treatment. The second aim of the study was to explore to what degree mental distress among substance users at admission to treatment could be explained by the same demographic factors as in population studies, or whether treatment differences or differences in substance use would be better predictors of mental distress in this population. Methods Patients (N = 185 who received inpatient substance use treatment in five different settings in Northern Norway participated in the study. HSCL-10 was used as a measure for mental distress at admission to treatment. The self-report measures AUDIT, DUDIT and DUDIT-E were used for measuring substance use and readiness for treatment. The patients' clinicians reported demographic and treatment factors. A three-block hierarchical multiple regression analysis was conducted to determine potential predictors of mental distress. Block 1 included demographic variables, Block 2 included treatment variables, and Block 3 substance use variables. Results Patients generally reported a high level of mental distress at admission to treatment, and 83% reported mental distress higher than the established cut-off level. Being female, having previously received psychiatric treatment, having a higher score on DUDIT and AUDIT, and using a larger number of substances all predicted a higher level of mental distress. The model explained 32% of the variance in mental distress. Conclusions Mental distress measured by the HSCL-10 can be a valuable concept in substance use treatment. The HSCL-10 can be useful in screening for patients who are in need of further assessment for psychiatric disorders. Female gender, previous psychiatric treatment, and higher use of substances all predicted a higher level of mental distress. The study underlines the importance of assessing the mental health of patients in substance use treatment.

Nivison Mary

2010-07-01

355

Camiones de alto tonelaje y su impacto en ciclo de vida de pavimentos asfálticos / Heavy load trucks and its impact in life cycle of asphalt pavements  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish En los últimos años se inició el debate sobre la factibilidad técnico-económica de introducir en la flota de transporte de carga configuraciones de alto tonelaje (CAT). Estas configuraciones superan el peso bruto total máximo de 45 t permitido en Chile, distribuyendo la carga sobre un mayor número d [...] e ejes. En Chile no existe experiencia en el uso de este tipo de configuraciones de carga, por lo que es prudente y necesario estudiar el impacto global que tendrían en el sistema de transporte interurbano si se implementan. En este trabajo se analiza en particular el impacto sobre los pavimentos asfálticos. Utilizando un enfoque mecanicista-empírico, se comparó el impacto en el ciclo de vida producido por CAT del tipo bitrén corto y largo, y configuraciones tradicionales del tipo camión-remolque y tracto-semirremolque. En la evaluación se consideraron diferentes estructuras de pavimento, condiciones climáticas y niveles de tránsito solicitante, representativos de la Región del Biobío. La evaluación mecanicista-empírica se realizó utilizando el método de diseño de pavimentos mecanicista francés Alize-LCPC, y los modelos de deterioro desarrollados por el Asphalt Institute. Para comparar distintos métodos de evaluación y modelos de deterioro, el ciclo de vida fue evaluado utilizando la Ley de Miner implementada en la guía de diseño MEPDG de Estados Unidos. Los resultados mostraron que el camión-remolque produce mayor daño en el pavimento, mientras que el tracto-semirremolque es el que produce menor daño, ambos con 45 t de peso bruto total. El bitrén largo de 75 t produce un impacto estructural levemente menor que el bitrén corto de 61 t. Sin embargo, se encontró evidencia teórica de que las CAT producen mayor ahuellamiento superficial en forma proporcional al peso bruto total. Abstract in english In recent years a discussion of the technical-economic feasibility of introduce the heavy load trucks (CAT) in goods transport fleet was started. This truck configurations overpass the maximum gross weight of 45 t permitted in Chile. In Chile there not exist experience of using this type of trucks, [...] whence is relevant to study the global impact of it over the interurban transport system. This paper discusses the impact of heavy load trucks over asphalt pavements. Using a mechanistic-empirical framework, the impact of two types of CAT, long and short bitrén, and a one and two units 45 tons trucks were compared along the life-cycle of the pavement. Assessment considers different pavement configurations, weather conditions and traffic levels, typical of the Bio Bio region. The mechanistic-empirical assessment was performed using the Alize-LCPC pavement design tool and the deterioration models of the Asphalt Institute. For comparing deteriorations, the life-cycle was assessed using the Miner Law implemented in the Mechanist-Empirical Pavement Design Guide, MEPDG. Results show that the one unit truck induces the greater damage over the pavement and that the two unit truck induces the lower damage. The long bitren (75 tons) induce a slightly lower impact than the short bitren. However it was found evidence that the CAT induce the greater rutting in the pavement surface, which increases linearly if the gross weight of the truck increases.

R, Díaz; T, Echaveguren; S, Vargas-Tejeda.

2012-04-01

356

Evaluation of Emotional Distress in Breast Cancer Patients  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Cancer has been known as a class of dangerous diseases which cause tremendous physical and emotional problems to both patients and their families. In spite of medical advances, cancer is still considered to be equal with death and pain. This study aims to analyze the emotional distress and the causes in breast cancer patients. Methods: This study was a quantitative study which tries to analyze the emotional distress in 82 breast cancer patients referred to the Radiotherapy and Oncology Department of Razi Hospital in Rasht, northern Iran. In this study, the emotional distress is analyzed based on a standard questionnaire which contains demographic information, distress thermometer, and a section devoted to the probable causes. Results: Among the 82 patients that participated in this study, 32 patients (39% suffered from severe emotional distress which had a statistically significant relationship (p<0.009 with the functional status of the patients. Taking care of children, fear, anxiety, difficulties of taking bath and wearing clothes, family problems, fever and nasal dryness are the most common issued related to emotional distress. Conclusion: Emotional distress can affect the quality of life of breast cancer patients. Therefore, oncology specialists should utilize mental health services to improve their patients’ mental health as well as to control the consequences of the disease.

Hamid Saeedi-Saedi

2015-02-01

357

Evaluation of Emotional Distress in Breast Cancer Patients  

Science.gov (United States)

Background Cancer has been known as a class of dangerous diseases which cause tremendous physical and emotional problems to both patients and their families. In spite of medical advances, cancer is still considered to be equal with death and pain. This study aims to analyze the emotional distress and the causes in breast cancer patients. Methods This study was a quantitative study which tries to analyze the emotional distress in 82 breast cancer patients referred to the Radiotherapy and Oncology Department of Razi Hospital in Rasht, northern Iran. In this study, the emotional distress is analyzed based on a standard questionnaire which contains demographic information, distress thermometer, and a section devoted to the probable causes. Results Among the 82 patients that participated in this study, 32 patients (39%) suffered from severe emotional distress which had a statistically significant relationship (p<0.009) with the functional status of the patients. Taking care of children, fear, anxiety, difficulties of taking bath and wearing clothes, family problems, fever and nasal dryness are the most common issued related to emotional distress. Conclusion Emotional distress can affect the quality of life of breast cancer patients. Therefore, oncology specialists should utilize mental health services to improve their patients’ mental health as well as to control the consequences of the disease.

Saeedi-Saedi, Hamid; Shahidsales, Soodabeh; Koochak-Pour, Mona; Sabahi, Emad; Moridi, Irene

2015-01-01

358

The five steps of comprehensive psychosocial distress screening.  

Science.gov (United States)

Despite the growing recognition of the impact psychosocial distress has on the quality of life of patients with cancer, the implementation of the National Comprehensive Cancer Network (NCCN) Distress Management Guidelines and the mandate of evidence-based policy for routine distress screening continue to lag. To speed adoption of the guideline, the American Psychosocial Oncology Society (APOS) and Yale School of Nursing (YSN) launched the Screening for Psychosocial Distress Program in 2014. The program resulted in the development of five steps necessary to carry out routine psychosocial distress screening. The steps are consistent with the NCCN Distress Management Guidelines and the new criterion for accreditation by the American College of Surgeons (ACS) Commission on Cancer as of 2015. These five steps are as follows: (1) screening, (2) evaluating, (3) referring, (4) following up, and (5) documenting and quality improvement. The purpose of this article is to summarize the detailed procedure of the five steps for cancer care professionals-including oncologists, nurses, psychiatrists, psychologists, and social workers-so they can manage psychosocial distress efficiently in their own clinical environments. PMID:25824699

Lazenby, Mark; Tan, Hui; Pasacreta, Nick; Ercolano, Elizabeth; McCorkle, Ruth

2015-05-01

359

Oxidative stress in fetal distress: Potential prospects for diagnosis  

Science.gov (United States)

Our aim was to investigate the relation between fetal distress and oxidative stress. Fetal distress was associated with increased concentration of superoxide in the fetal blood and with significant increase of the level of H2O2 in both maternal and fetal blood. The activity of superoxide dismutase was increased roughly sixfold (p < 0.01) in the maternal [7330 ± 2240 U/g of hemoglobin in controls (C) and 36811 ± 16862 U/g in fetal distress (FD)] and fetal blood (C: 5930 ± 2641 U/g; FD: 41912 ± 17133 U/g). In contrast, fetal distress was related to a considerable decrease of catalase activity in both maternal (C: 26011 ± 8811 U/g; FD: 7212 ± 1270 U/g) and fetal blood (C: 37194 ± 9191 U/g; FD: 6173 ± 1965 U/g). From this we concluded that in fetal distress, the maternal and fetal bloods are exposed to superoxide- and H2O2-mediated oxidative stress, which could be initiated by hypoxic conditions in the fetal blood and placenta. A tremendous increase/decrease of the activities of superoxide dismutase/catalase in the blood of women bearing a distressed fetus in comparison to healthy subjects implies that the assessment of superoxide dismutase/catalase activity could be of use for establishing a timely and accurate ante- or intrapartum diagnosis of fetal distress. PMID:20716946

Rai?evi?, Saša; ?ubrilo, Dejan; Arsenijevi?, Slobodan; Vuk?evic, Gordana; Živkovi?, Vladimir; Vuleti?, Milena; Barudži?, Nevena; Andjelkovi?, Nebojša; Antonovi?, Olga

2010-01-01

360

Adoption RCCP (roller compacted concrete pavement) for the large lumber yard pavement at the harbor pier; Daikibo kowan futo yard eno RCCP no tekiyo  

Energy Technology Data Exchange (ETDEWEB)

RCCP (roller compacted concrete pavement) is largely promising to reduce a total cost by easy and rapid work, labor saving and superior durability. This paper reports RCCP technology adopted for the large open-air lumber yard pavement of nearly 73,000m{sup 2} at the Hakozaki harbor pier in Fukuoka city, and the survey result on its usability. According to design loads and design CBR of 5-7% for subgrade soil, a field mixing cement stabilized subgrade (CTB) was adopted considering a design base bending strength for RCC slab of 5MP, slab thickness of 25cm, and load transfer at RCC slab joint and erosion resistance for upper subgrade. Pavement process is composed of transport of RCC slabs, leveling, initial roller compaction, secondary roller compaction, finishing roller compaction, curing, joint cutting and opening to users. Joint cutting was carried out by dry cutter to save early cutting and cleaning after cutting. Fresh joint system was adopted for longitudinal joints. The pavement is favorable during nearly 8 years after opening to users. 5 refs., 15 figs., 2 tabs.

Chidori, H. [Fukuoka City Office, Fukuoka (Japan); Kagata, M.; Kodama, T. [Kajima Road Co. Ltd., Tokyo (Japan)

1998-06-10

361

Psychological and physical distress of cancer patients during radiotherapy  

International Nuclear Information System (INIS)

Purpose: patients undergoing radiotherapy have physical and psychological symptoms related to the underlying disease and the treatment. In order to give the best possible support to the patients, more knowledge about the amount and the changing of distress in the course of radiotherapy is of essentially importance. Methods: The distress was measured in a consecutive sample of cancer patients (n=82) undergoing radiotherapy. Each patient was given the EORTC-QLQ-C30, the HADS and a special questionnaire which ascertain radiotherapy-specific items before starting the radiotherapy, at the onset of radiotherapy, in the third week of radiotherapy and 3 weeks after the end of radiotherapy. Results: within the first week of treatment the psychological distress of the patients is increasing; 98.8 % of the patients are 'moderate distressed', 46 % 'severe distressed'. General physical symptoms seem not to be affected by the radiotherapy, there is no changing. The distress caused by the organization of the radiotherapy is decreasing, while therapy-related symptoms are increasing in the course of radiotherapy. Even after the end of the therapy these symptoms keep on causing distress, sometimes in a higher amount than before. A correlation between sex, sort of cancer and curative or palliative treatment and the amount of distress was found. Conclusion: the results stress the importance of adequate emotional support for patients undergoing radiotherapy especially in the first week ofdiotherapy especially in the first week of treatment and after the treatment. There is a need for the development of a valid radiotherapy - questionnaire in order to be able to measure the distress of these patients. (author)

362

Termômetro de Distress: validação de um instrumento breve para avaliação diagnóstica de pacientes oncológicos / Distress Thermometer: validation of a brief screening instrument to detect distress in oncology patients  

Scientific Electronic Library Online (English)

Full Text Available A literatura especializada disponibiliza instrumentos de medida de estresse de aplicação geral, os quais vêm sendo empregados em diferentes contextos ocupacionais e em saúde. Mas, desde 1997, a National Comprehensive Cancer Network (NCCN) recomenda a adoção de uma medida específica para pacientes on [...] cológicos. Considerando, portanto, o interesse clínico e científico de desenvolver futuros estudos de meta-análise em Oncologia, que incluam amostras brasileiras, realizaram-se a adaptação e a validação do Termômetro de Distress (TD). A eficácia de avaliação do TD foi verificada por meio da comparação com a Escala de Ansiedade e Depressão (HAD), um instrumento clinicamente estabelecido de avaliação de distress. Para tanto, avaliou-se uma amostra de 83 pacientes, que responderam ao TD e ao HAD. Os dados foram submetidos ao SPSS 15.0. Os resultados indicam uma sensibilidade de 82% e uma especificidade de 98%, o que indica que o TD é viável e eficiente para avaliar o distress psicológico. Abstract in english The specialized literature provides instruments measuring stress for general application. Those instruments have been employed in occupational and health contexts. But since 1997, the National Comprehensive Cancer Network (NCCN) recommends the adoption of a specific measuring instrument for the asse [...] ssment of cancer patients. Considering the existence of clinical and scientific interest to develop future meta-analysis studies in the field of Oncology, which will include Brazilian samples, the adaptation and validation of the Distress Thermometer (TD) was undertaken. The effectiveness of the TD in assessing distress was verified by comparison with the Anxiety and Depression Scale (HAD), a clinically established tool for evaluating distress. In order to that, a sample of 83 patients answered the TD and the HAD. The data were analyzed using SPSS 15.0. Results of the analysis indicated 82% for sensitivity and 98% for specificity. Using the TD appeared feasible and effective for psychological distress screening.

363

Termômetro de Distress: validação de um instrumento breve para avaliação diagnóstica de pacientes oncológicos Distress Thermometer: validation of a brief screening instrument to detect distress in oncology patients  

Directory of Open Access Journals (Sweden)

Full Text Available A literatura especializada disponibiliza instrumentos de medida de estresse de aplicação geral, os quais vêm sendo empregados em diferentes contextos ocupacionais e em saúde. Mas, desde 1997, a National Comprehensive Cancer Network (NCCN recomenda a adoção de uma medida específica para pacientes oncológicos. Considerando, portanto, o interesse clínico e científico de desenvolver futuros estudos de meta-análise em Oncologia, que incluam amostras brasileiras, realizaram-se a adaptação e a validação do Termômetro de Distress (TD. A eficácia de avaliação do TD foi verificada por meio da comparação com a Escala de Ansiedade e Depressão (HAD, um instrumento clinicamente estabelecido de avaliação de distress. Para tanto, avaliou-se uma amostra de 83 pacientes, que responderam ao TD e ao HAD. Os dados foram submetidos ao SPSS 15.0. Os resultados indicam uma sensibilidade de 82% e uma especificidade de 98%, o que indica que o TD é viável e eficiente para avaliar o distress psicológico.The specialized literature provides instruments measuring stress for general application. Those instruments have been employed in occupational and health contexts. But since 1997, the National Comprehensive Cancer Network (NCCN recommends the adoption of a specific measuring instrument for the assessment of cancer patients. Considering the existence of clinical and scientific interest to develop future meta-analysis studies in the field of Oncology, which will include Brazilian samples, the adaptation and validation of the Distress Thermometer (TD was undertaken. The effectiveness of the TD in assessing distress was verified by comparison with the Anxiety and Depression Scale (HAD, a clinically established tool for evaluating distress. In order to that, a sample of 83 patients answered the TD and the HAD. The data were analyzed using SPSS 15.0. Results of the analysis indicated 82% for sensitivity and 98% for specificity. Using the TD appeared feasible and effective for psychological distress screening.

Cristiane Sant'Anna Decat

2009-12-01

364

Reuse of Lathe Waste Steel Scrap in Concrete Pavements  

Directory of Open Access Journals (Sweden)

Full Text Available These project works assess on the study of the workability and mechanical strength properties of the concrete reinforced with industrialized waste fibers or the recycled fibers. In each lathe industries wastes are available in form of steel scraps are yield by the lathe machines in process of finishing of different machines parts and dumping of these wastes in the barren soil contaminating the soil and ground water that builds an unhealthy environment. Now a day’s these steel scraps as a waste products used by innovative construction industry and also in transportation and highway industry. In addition to get sustainable progress and environmental remuneration, lathe scrap as worn-recycle fibers with concrete are likely to be used. When the steel scrap reinforced in concrete it acquire a term; fiber reinforced concrete and steel fibers in concrete defined as steel fiber reinforced concrete (SFRC.Different experimental studies are done to identify about fresh and hardened concrete properties of steel scrap fiber reinforced concrete (SSFRC and their mechanical properties are found to be increase due to the addition of steel scrap in concrete i.e. compressive strength, flexural strength, impact strength, fatigue strength and split tensile strength were increased but up to 0.5-2% scrap content . When compared with usual concrete to SSFRC, flexural strength increases by 40% and considerable increases in tensile and compressive strength. These steel scrap also aid to improve the shrinkage reduction, cracking resistance i.e. preventing crack propagation and modulus of elasticity. The workability of fresh SSFRC are carried out by using slump test but it restricted to less scrap contents. This work focuses on the enhancement of structural strength and improvement in fatigue life of concrete pavements by reuse of scrap steel in concrete. These concrete roads with SSFRC promises an appreciably eminent design life, offer superior serviceability and minimize crack growth and corrosion. The pioneer idea of this work is the reuse of waste lathe scrap as recycled steel fibers, which provides more cost-effective and eco-friendly sustainable SFRC PAVEMENTS.

Pooja Shrivastavaa

2014-12-01

365

Utilizationof Hypo Sludge by Eco-Efficient Development of Rigid Pavement in Rural Roads  

Directory of Open Access Journals (Sweden)

Full Text Available The paperproducing industry generates various wastes coming out from the various processes. From the preliminary waste named as hypo sludge, due to its low calcium is taken out to replace the cement in concrete. Major initiatives are needed in India to use these large volumes in construction industry especially in rigid pavement construction and other infrastructure projects. Moreover Use of Hypo Sludge in construction of rigid pavement will improve transportation functionality and ecological sustainability and results in improved traffic safety and reduced life-cycle cost. Use of Hypo Sludge in construction of rigid pavement will benefit urban growth, public health and surrounding communities by encouraging smart growth by integrating and guiding future growth. It is also needed to reduce the cost of concrete pavement for rural development in India. So our study is concerned with eco-efficient utilization of Hypo sludge as partial replacement of cement in concrete for development of low cost rigid pavement of rural road infrastructure.The Hypo sludge was replaced within the range of 10-40% by weight of cement. In the present study, 5 different mixes of Hypo Sludge are tested for parameters like: compressive strength, flexural strength and cost

Prof. Jayeshkumar Pitroda1 , Dr. L.B.Zala2 , Dr.F.S.Umrigar

2013-09-01

366

Evaluating the Infiltration Performance of Eight Dutch Permeable Pavements Using a New Full-Scale Infiltration Testing Method  

Directory of Open Access Journals (Sweden)

Full Text Available Permeable pavements are a type of sustainable urban drainage system (SUDS technique that are used around the world to infiltrate and treat urban stormwater runoff and to minimize runoff volumes. Urban stormwater runoff contains significant concentrations of suspended sediments that can cause clogging and reduce the infiltration capacity and effectiveness of permeable pavements. It is important for stormwater managers to be able to determine when the level of clogging has reached an unacceptable level, so that they can schedule maintenance or replacement activities as required. Newly-installed permeable pavements in the Netherlands must demonstrate a minimum infiltration capacity of 194 mm/h (540 l/s/ha. Other commonly used permeable pavement guidelines in the Netherlands recommend that maintenance is undertaken on permeable pavements when the infiltration falls below 0.50 m/d (20.8 mm/h. This study used a newly-developed, full-scale infiltration test procedure to evaluate the infiltration performance of eight permeable pavements in five municipalities that had been in service for over seven years in the Netherlands. The determined infiltration capacities vary between 29 and 342 mm/h. Two of the eight pavements show an infiltration capacity higher than 194 mm/h, and all infiltration capacities are higher than 20.8 mm/h. According to the guidelines, this suggests that none of the pavements tested in this study would require immediate maintenance.

Floris Boogaard

2014-07-01

367

The Edison Environmental Center Permeable Pavement Site: Initial Results from a Stormwater Control Designed for Monitoring - Slides  

Science.gov (United States)

There exist few detailed studies of full-scale, replicated, actively-used permeable pavement systems. Practitioners need additional studies of permeable pavement systems in its intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage condit...

368

The Edison Environmental Center Permeable Pavement Site: Initial Results from a Stormwater Control Designed for Monitoring - Paper  

Science.gov (United States)

There exist few detailed studies of full-scale, replicated, actively-used permeable pavement systems. Practitioners need additional studies of permeable pavement systems in its intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage condit...

369

A Method to Estimate the Dynamic Displacement and Stress of a Multi-layered Pavement with Bituminous or Concrete Materials  

Directory of Open Access Journals (Sweden)

Full Text Available In this research work, a method to estimate the dynamic characteristics of a multilayered pavement with bituminous or concrete materials is proposed. A mechanical model is established to investigate the dynamic displacement and stress of the multi-layered pavement structure. Both the flexible and the rigid pavements, corresponding to bituminous materials and concrete materials, respectively, are studied. The theoretical solutions of the multi-layered pavement structure are deduced considering the compatibility condition at the interface of the structural layers. By introducing FFT (Fast Fourier Transform algorithm, some numerical results are presented. Comparisons of the theoretical and experimental result implied that the proposed method is reasonable in predicting the stress and displacement of a multi-layered pavement with bituminous or concrete materials. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6071

Zheng LU

2014-12-01

370

The balancing act: psychiatrists' experience of moral distress.  

Science.gov (United States)

Experiences of moral distress encountered in psychiatric practice were explored in a hermeneutic phenomenological study. Moral distress is the state experienced when moral choices and actions are thwarted by constraints. Psychiatrists describe struggling 'to do the right thing' for individual patients within a societal system that places unrealistic demands on psychiatric expertise. Certainty on the part of the psychiatrist is an expectation when judgments of dangerousness and/or the need for coercive treatments are made. This assumption, however, ignores the uncertainty and complexity of reality. Society entrusts psychiatrists to care for and treat those among its most vulnerable members: persons deemed to have a severely diminished capacity for autonomy due to a mental disorder. Simultaneously, psychiatrists are held accountable by society for the protection of the public. Moral distress arose for psychiatrists in their efforts to fulfill both roles. They described an 'outsider/insider' status and the ways in which they attempted to cope with moral distress. PMID:17703374

Austin, Wendy J; Kagan, Leon; Rankel, Marlene; Bergum, Vangie

2008-03-01

371

Nurses Managing Patients' Pain May Experience Moral Distress.  

Science.gov (United States)

Bedside nurses care for patients with pain every day but the task is often challenging. A previous qualitative study that investigated nurses' experiences as they treated patients with pain suggested that nurses may suffer from moral distress if they are unsuccessful in providing adequate pain relief. As 20 of the original 48 nurses interviewed described frustration and distress when constrained from doing the right thing to provide pain relief for their patients, the purpose of this secondary qualitative analysis was to answer new research questions on nurse moral distress related to managing pain. Findings indicated that difficulties in nurse/physician communication and lack of pain education were contributors to nurses' frustrations and provided barriers to optimal pain management. Many participants indicated a need for interprofessional pain management education. Further investigation is needed to clarify the impact of moral distress on nurses managing hospitalized patients' pain. PMID:24836821

Bernhofer, Esther I; Sorrell, Jeanne M

2014-05-16

372

'Moral distress'--time to abandon a flawed nursing construct?  

Science.gov (United States)

Moral distress has been characterised in the nursing literature as a major problem affecting nurses in all healthcare systems. It has been portrayed as threatening the integrity of nurses and ultimately the quality of patient care. However, nursing discourse on moral distress is not without controversy. The notion itself is conceptually flawed and suffers from both theoretical and practical difficulties. Nursing research investigating moral distress is also problematic on account of being methodologically weak and disparate. Moreover, the ultimate purpose and significance of the research is unclear. In light of these considerations, it is contended that the notion of moral distress ought to be abandoned and that concerted attention be given to advancing inquiries that are more conducive to improving the quality and safety of moral decision-making, moral conduct and moral outcomes in nursing and healthcare domains. PMID:24311238

Johnstone, Megan-Jane; Hutchinson, Alison

2015-02-01

373

47 CFR 97.405 - Station in distress.  

Science.gov (United States)

...COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES AMATEUR RADIO SERVICE Providing Emergency Communications ...No provision of these rules prevents the use by an amateur station in distress of any means at its...

2010-10-01

374

Family Support, Self-Rated Health, and Psychological Distress  

OpenAIRE

Background: Comprehensive health care is becoming an important issue; however, little is known about the complex relationships between perceived family support, self-rated health, and psychological distress in mixed middle-aged/older primary care patient samples.

Cano, Annmarie; Scaturo, Douglas J.; Sprafkin, Robert P.; Lantinga, Larry J.; Fiese, Barbara H.; Brand, Frank

2003-01-01

375

Recycling of radioactive oil sludge waste into pavement brick  

International Nuclear Information System (INIS)

Malaysia produces about 1450 tons of radioactive oil sludge waste per year and there is an urgent need to find a permanent solution to the storage and disposal of this radioactive waste problem. Several treatment methods such bacteria farming, ultracentrifuge, steam reforming and incineration are currently being used but the core issue of the radioactive material in the oil sludge had not been solved. The paper relates a study on utilizing the radioactive component of the oil sludge and turning them into pavement brick. Characteristic study of this radioactive component by XRD and XRF show that it mainly comprised of quartz and anorthite minerals. While the radioactivity analysis by gamma technique shows that more than 90 % of this radioactivity comes from this soil component with Ra-226 and Ra-228 as the main radionuclides. A vitrified brick was then produced from this sediment by mixing it with low radioactive local red clay. The result also shows that the formation of the vitrified layer may be due high content of K in the red clay. Tensile test on the brick shows that it has more than four times the strength of commercial clay brick. Long duration leaching test on the brick also shows that there is no dissolution of radionuclide from the brick. (author)

376

Effects of conductive fillers on temperature distribution of asphalt pavements  

International Nuclear Information System (INIS)

The sun provides a cheap and abundant source of clean and renewable energy. Solar cells have been used to capture this energy and generate electricity. A more useful form of the solar cell would be asphalt pavements, which get heated up by solar radiation. Graphite powders are utilized as thermal conductive fillers to make an asphalt collector conductive so as to improve the efficiency of the asphalt collector. Accounting for the important application conditions and evaluating the effects of the heat conductive materials and the solar energy absorbability of the conductive asphalt collector, a finite element model has been developed to predict temperature distributions in the conductive asphalt solar collector. In this study, an experimental validation exercise was conducted using the measured data taken from full-depth asphalt slabs. Validation results showed that the model can satisfactorily predict the temperature distributions in asphalt concrete slabs. The optimal depth is 25-50 mm for placing pipes that serve as the heat exchanger. Meanwhile, the effect of the surroundings on the solar energy potential of the asphalt collector was noticeable.

377

Radioactivity assessment of pavement blocks made with itabirite ore waste  

International Nuclear Information System (INIS)

Banded Iron Formation, also known as itabirite is a rock composed of silica and hematite layers. The iron ore exploitation from itabirite is carried out by separating the silica by chemical processes, generating high amount of sandy waste that are stocked in dams. In contrast, the construction of dwellings and other buildings consumes about 210 million tons of aggregates (sand and gravel) annually in Brazil and the excessive extraction of river sand causes many environmental impacts. Studies have indicated the technical feasibility of using these waste ore like aggregates in cement artifacts. However, natural occurring radionuclides are present in many natural resources. Human activities may enhance concentrations of radionuclides and/or enhance potential of exposure to naturally occurring radioactive material (NORM/TENORM). The industrial residues containing radionuclides have been receiving a considerable global attention, because of the large amounts of NORM containing wastes and the potential long term risks of long-lived radionuclides. Although a significant amount of primordial radionuclides by primary geological process is not expected in itabirite, it may occur due to late geologic process. In this concern, this work presents an assessment of natural radionuclides contents in this sand waste, in cement and in regular sand. Also the radon exhalation rate of pavement blocks made with varied contents of the itabirite mining residue was measured by using a continuous radon measuring equipment in a closed circuit. A preliminary estimation of the potential radiological risk by using this ore waste in place of regular sand is also presented. (author)

378

Mindful Walking in Psychologically Distressed Individuals: A Randomized Controlled Trial  

OpenAIRE

Background. The aim of this randomized, controlled study was to investigate the effectiveness of a mindful walking program in patients with high levels of perceived psychological distress. Methods. Participants aged between 18 and 65 years with moderate to high levels of perceived psychological distress were randomized to 8 sessions of mindful walking in 4 weeks (each 40 minutes walking, 10 minutes mindful walking, 10 minutes discussion) or to no study intervention (waiting group). Primary ou...

Willich, S. N.; Michalsen, A.; Fischer, H. F.; Roll, S.; Binting, S.; Ortiz, M.; Reese, F.; Roesner, E. J.; Teut, M.; Brinkhaus, B.

2013-01-01

379

Prediction of Financial Distress -A Case Study of Indian Companies  

OpenAIRE

Financial distress is of crucial importance in financial management especially in the case of competitive environment. Failure is not an impulsive outcome and it grows constantly in stages. A spontaneous protective effort could be accommodated if the company is anticipated to be proceeding in the direction of potential bankruptcy and this can help alleviate the financial distress to all investors and decrease the costs of bankruptcy. This study extends a failure prediction model for Indian co...

Amalendu Bhunia; Sri Islam Uddin Khan; Somnath Mukhuti

2011-01-01

380

Corporate debt restructuring: Evidence on lender coordination in financial distress  

OpenAIRE

In the recent theoretical literature on lending risk, the coordination problem in multicreditor relationships have been analyzed extensively. We address this topic empirically, relying on a unique panel data set that includes detailed credit-file information on distressed lending relationships in Germany. In particular, it includes information on creditor pools, a legal institution aiming at coordinating lender interests in borrower distress. We report three major findings. First, the existen...

Brunner, Antje; Krahnen, Jan Pieter

2001-01-01

381

Financial Distress with Family Farm Transfer in Six European Countries  

OpenAIRE

Many potential young farmers face the difficult choice between farming or a city career. An important criterion in this decision is the financial distress that goes with farming. Using data for the 1990s, the present study compared the financial distress after take-over of family farms by the next generation, in six European countries: Denmark, France, Germany, Spain, the Netherlands and the United Kingdom. The principles of inheritance and succession and the fiscally appraised value of the f...

Bommel, K. H. M.; Veen, H. B.; Venema, G. S.

2004-01-01

382

The adult respiratory distress syndrome bronchogenic pulmonary tuberculosis.  

OpenAIRE

In three cases of pulmonary tuberculosis associated with the adult respiratory distress syndrome the clinical features, which were similar to those of patients with miliary tuberculosis and adult respiratory distress syndrome, included a history of cough, fever, and dyspnoea on effort, and the physical signs of fever, tachypnoea, pulmonary adventitious sounds, tachycardia, and hepatomegaly. In these cases the radiological features, though suggestive of diffuse pulmonary oedema, were more prom...

Dyer, R. A.; Potgieter, P. D.

1984-01-01

383

Reducing teachers' psychological distress through a mindfulness training program  

OpenAIRE

Teachers constitute one of the professional collectives most affected by psychological problems. The purpose of this quasi-experimental study is to examine the efficacy of a mindfulness training programme to reduce psychological distress in a group of teachers. The sample comprised 68 teachers of Secondary School Education, from various public schools; half of them formed the experimental group, and the another half the control group. The levels of psychological distress were measured, in bot...

Franco, Clemente; Cangas, Adolfo J.; Moreno San Pedro, Emilio; Gallego, Jose?

2010-01-01

384

Emotional and Physical Distress Relief Using a Novel Endorphinergic Formulation  

Directory of Open Access Journals (Sweden)

Full Text Available While the endogenous opioid system has generally been associated with regulation of pain, it also modulates the experience of distress and may play a central role in many psychiatric and neurodevelopmental disorders. Decades of preclinical research on the analgesic effects of endogenous opioids, i.e., endorphins, suggests that opioid receptors have plastic bimodal (inhibitory/excitatory properties that may explain conflicting findings in clinical research. An exploratory study with 60 healthy volunteer participants, using a cold pressor-induced pain paradigm, found evidence that a combination of a nutraceutical agent that enhances endorphin release (Endorphin Enhancer with one that switches opioid receptors from an excitatory to inhibitory mode (Opioid Receptor Switcher not only increases pain tolerance but also reduces emotional and physical distress. This discovery led to clinical application of a critically formulated endorphinergic treatment in 203 case studies over a two-year period. Findings revealed the remarkable clinical efficacy and safety of this treatment in the relief of chronic emotional and physical distress, including anxiety, anger, depression, cravings, and hyperalgesia, as well as enhancement of well-being, productivity, mental clarity, relationships, and an adaptive response to life’s stresses. These studies provide new insights into the role of endogenous opioid system imbalances in the development, treatment, and prevention of dysfunctional emotional and physical distress. We postulate that an Endorphinergic Distress Syndrome (EDS consists of abnormal endorphin levels together with opioid receptors predominately in their excitatory mode. EDS may account for many core distress symptoms associated with chronic anxiety, addictions, pain, as well as affective personality, autism spectrum, attention-deficit, and distress-related medical problems. Our research has led to new endorphinergic formulations, combining Endorphin Enhancers, such as caffeine, with Opioid Receptor Switchers, such as n-acetylcysteine, for the relief of emotional and physical distress. Our studies also provide a novel method to reverse the anxiogenic effects of caffeine and related hyperexcitatory substances.

Steven Crain

2013-09-01

385

Intrapericardial teratoma--neonatal cardiorespiratory distress amenable to surgery.  

Science.gov (United States)

Intrapericardial teratoma in early infancy produces critically severe cardiorespiratory distress and often results in the death of the infant. A recent patient in our newborn nursery displayed the distinctive combination of cardiorespiratory distress and enlargement of the "cardiothymic" silhouette. The echocardiographic demonstration of pericardial effusion and cardiac displacement suggested the diagnosis. Our patient's mass received the early recognition necessary for a successful surgical outcome. PMID:7463301

Zerella, J T; Halpe, D C

1980-12-01

386

Parental separation and adult psychological distress: material and relational pathways  

OpenAIRE

The association between parental separation occurring during childhood and adult psychological distress is well established, however the potential mechanisms involved in translating the experience of parental separation into the increased risk of reporting psychological distress is unclear and little investigated. Previous literature indicates that material and relational factors may be involved and that these two pathways are likely to be linked across the life course. The identification of ...

Lacey, R. E.

2012-01-01

387

Schizotypy, psychotic-like experiences and distress: An interaction model  

OpenAIRE

Psychotic-like experiences (PLEs) have been found to exist on a continuum in both general and clinical populations. Such experiences may characterize normal and abnormal variations in personality, as well as prodromal or high risk states for the development of psychotic disorders. High risk paradigms tend to emphasize distress and impairment associated with PLEs, yet the extent to which individuals find PLEs to be distressing likely depends on moderating factors. In particular, individuals hi...

Kline, Emily; Wilson, Camille; Ereshefsky, Sabrina; Nugent, Katie L.; Pitts, Steven; Reeves, Gloria; Schiffman, Jason

2012-01-01

388

Asian elephants (Elephas maximus) reassure others in distress  

OpenAIRE

Contact directed by uninvolved bystanders toward others in distress, often termed consolation, is uncommon in the animal kingdom, thus far only demonstrated in the great apes, canines, and corvids. Whereas the typical agonistic context of such contact is relatively rare within natural elephant families, other causes of distress may trigger similar, other-regarding responses. In a study carried out at an elephant camp in Thailand, we found that elephants affiliated significantly more with othe...

Plotnik, Joshua M.; Waal, Frans B. M.

2014-01-01

389

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

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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.

Cao Peng

2013-01-01

390

Acute Respiratory Distress Syndrome in Children  

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Full Text Available Acute lung injury (ALI and acute respiratory distress syndrome (ARDS are an important challenge for pediatric intensive care units. These disorders are characterized by a significant inflammatory response to a local (pulmonary or remote (systemic insult resulting in injury to alveolar epithelial and endothelial barriers of the lung, acute inflammation and protein rich pulmonary edema. The reported rates in children vary from 8.5 to 16 cases/1000 pediatric intensive care unit (PICU admissions. The pathological features of ARDS are described as passing through three overlapping phases-an inflammatory or exudative phase (0-7 days, a proliferative phase (7-21 days and lastly a fibrotic phase. The treatment of ARDS rests on good supportive care and control of initiating cause. Ventilatory modes and nursing interventions to optimize patient outcomes are identified. The goal of ventilating patients with ALI/ARDS should be to maintain adequate gas exchange. Lung protective mechanical ventilation with optimal lung recruitment is the mainstay of supportive therapy. This can be achieved by use of optimum PEEP, low tidal volume and appropriate FiO2. New therapeutic modalities refer to corticosteroid, high frequency ventilation, inhaled nitric oxide, prone positioning and surfactant treatment. Well-designed follow up studies are needed. [Archives Medical Review Journal 2009; 18(4.000: 241-259

Dincer Yildizdas

2009-08-01

391

An Unusual Cause of Recurrent Respiratory Distress  

Directory of Open Access Journals (Sweden)

Full Text Available A one and a half years old boy presented with recurrent episodes of respiratory distress, accompanied by dry non spasmodic cough and characterized by appearance of a continuous stridor showing no positional variation. The child was symptomatic since early infancy. Parents also complained of inability to gain weight as compared to other siblings.  There was no history of foreign body ingestion or complaints of asthma or tuberculosis in the family. General physical examination revealed tachypnea and biphasic stridor in a malnourished and stunted child in the absence of any significant lymphadenopathy or oral thrush.On systemic examination, bilaterally, stridorous sounds were auscultated. Primary investigations on the child showed minimal reflux on gastro-esophageal reflux isotope scan, a normal chest roentgenogram, negative sweat chloride test and negative serology for HIV (Human immuno­deficiency virus. Echocardiography performed on the child revealed a structurally normal heart. On conducting further investigations, bronchoscopy detected a bulge in the anterior tracheal wall while barium swallow displayed indentation in the upper esophagus. The MRI (magnetic resonance imaging subsequently conducted clinched the underlying clinical condition. The MRI images are depicted below.

Joshi Neha

2010-12-01

392

Marital distress and disease progression: A systematic review  

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Full Text Available Objective: To review the state of research on the association between marital distress and disease progression. Methods: The PubMed Central, Wiley Interscience, Sciencedirect, Biomed central and Springer-link were searched to identify studies published between January 1984 and October 2012 on disease progression. Articles meeting the following criteria were selected for review: 1 study subjects were spouses, 2 the article was published within the past 28 years in a peer-reviewed journal, and 3 the research included at least one of the following outcomes-marital distress or disease progression. Articles were different on time span, the number of surveys, and the definition of disease. Results: Out of 72 screened articles, 18 met our criteria. Research demonstrates that marital distress and disease progression appear to have bidirectional influence on each other. Conclusion: Marital distress has a significant effect on disease progression. This article summarizes what is known about the association of marital distress on disease progression among spouses with disease. The authors speculate that associations between marital distress and disease progression will motivate policy makers in developing countries to allocate more resources towards spousal service.

Ming Guan

2013-09-01

393

Asian elephants (Elephas maximus) reassure others in distress.  

Science.gov (United States)

Contact directed by uninvolved bystanders toward others in distress, often termed consolation, is uncommon in the animal kingdom, thus far only demonstrated in the great apes, canines, and corvids. Whereas the typical agonistic context of such contact is relatively rare within natural elephant families, other causes of distress may trigger similar, other-regarding responses. In a study carried out at an elephant camp in Thailand, we found that elephants affiliated significantly more with other individuals through directed, physical contact and vocal communication following a distress event than in control periods. In addition, bystanders affiliated with each other, and matched the behavior and emotional state of the first distressed individual, suggesting emotional contagion. The initial distress responses were overwhelmingly directed toward ambiguous stimuli, thus making it difficult to determine if bystanders reacted to the distressed individual or showed a delayed response to the same stimulus. Nonetheless, the directionality of the contacts and their nature strongly suggest attention toward the emotional states of conspecifics. The elephants' behavior is therefore best classified with similar consolation responses by apes, possibly based on convergent evolution of empathic capacities. PMID:24688856

Plotnik, Joshua M; de Waal, Frans B M

2014-01-01

394

Asian elephants (Elephas maximus reassure others in distress  

Directory of Open Access Journals (Sweden)

Full Text Available Contact directed by uninvolved bystanders toward others in distress, often termed consolation, is uncommon in the animal kingdom, thus far only demonstrated in the great apes, canines, and corvids. Whereas the typical agonistic context of such contact is relatively rare within natural elephant families, other causes of distress may trigger similar, other-regarding responses. In a study carried out at an elephant camp in Thailand, we found that elephants affiliated significantly more with other individuals through directed, physical contact and vocal communication following a distress event than in control periods. In addition, bystanders affiliated with each other, and matched the behavior and emotional state of the first distressed individual, suggesting emotional contagion. The initial distress responses were overwhelmingly directed toward ambiguous stimuli, thus making it difficult to determine if bystanders reacted to the distressed individual or showed a delayed response to the same stimulus. Nonetheless, the directionality of the contacts and their nature strongly suggest attention toward the emotional states of conspecifics. The elephants’ behavior is therefore best classified with similar consolation responses by apes, possibly based on convergent evolution of empathic capacities.

Joshua M. Plotnik

2014-02-01

395

How to transform an asphalt concrete pavement into a solar turbine  

International Nuclear Information System (INIS)

Highlights: • We create a system for harvesting energy from asphalt concrete. • We create an artificial porosity in the asphalt concrete. • We connect a chimney to this porosity. • Differences in temperature produce an air flow. • This air flow serves also for cooling down the pavement. - Abstract: Asphalt concrete can absorb a considerable amount of the incident solar radiation. For this reason asphalt roads could be used as solar collectors. There have been different attempts to achieve this goal. All of them have been done by integrating pipes conducting liquid, through the structure of the asphalt concrete. The problem of this system is that all pipes need to be interconnected: if one is broken, the liquid will come out and damage the asphalt concrete. To overcome these limitations, in this article, an alternative concept is proposed:parallel air conduits, where air can circulate will be integrated in the pavement structure. The idea is to connect these artificial pore volumes in the pavement to an updraft or to a downdraft chimney. Differences of temperature between the pavement and the environment can be used to create an air flow, which would allow wind turbines to produce an amount of energy and that would cool the pavement down in summer or even warm it up in winter. To demonstrate that this is possible, an asphalt concrete prototype has been created and basics calculations on the parameters affecting the system have been done. It has been found that different temperatures, volumes of air inside the asphalt and the difference of temperature between the asphalt concrete and the environment are critical to maximize the air flow through the pavement. Moreover, it has been found that this system can be also used to reduce the heat island effect

396

CSR Actions and Financial Distress: Do Firms Change Their CSR Behavior When Signals of Financial Distress Are Identified?  

OpenAIRE

Many studies have focused on the relation between financial and economic performance of firms and their actions on corporate social responsibility (CSR). However, few of them analyze CSR actions of firms facing decline. The purpose of this paper is to analyze if a recognized situation of financial distress has an impact on CSR strategies and modifies the attitude of a set of firms towards responsible behavior. We use CSR information of healthy and distressed US firms, d...

Arjola Mecaj; María Isabel González Bravo

2014-01-01

397

Synthesis study of nondestructive testing devices for use in overlay thickness design of flexible pavements  

Science.gov (United States)

A ready reference for highway engineers who are interested in purchasing nondestructive testing (NDT) equipment for use in designing overlays for flexible pavements was prepared. All commercially available equipment is described. Information includes basic descriptions plus current prices quoted by the manufacturers/distributors. To determine user comments, a questionnaire was sent to nine State agencies, and one Federal agency. The responses to these questionnaires are summarized. Overlay thickness design procedures for flexible pavements are reviewed. Important components related to the use of NDT deflection measuremnts in overlay design are identified and addressed. Summary tables of equipment characteristics and overlay design procedures are presented.

Smith, R. E.; Lytton, R. L.

1984-04-01

398

Polymer concrete for precast repair of continuously reinforced concrete pavement on IH 30, near Mt. Pleasant  

Science.gov (United States)

Two punchout repairs made in a continuously reinforced concrete pavement (CRCP) using precast portland cement panels are described. The two repairs, one 1.44 sq. ft., the other 36 sq. ft., were completed and opened to traffic in one afternoon. This technique provides a rapid method of repair that produces a repair that is structurally as good or better than the surrounding pavement. With a trained crew, the repair time can be reduced and thus reducing lane closure time. Since lane closure time is a critical consideration in high volume highways, this method is cost effective in those areas.

Meyer, A. M.; McCullough, B. F.; Fowler, D. W.

1981-08-01

399

A comprehensive approach for the assessment of in-situ pavement density using GPR technique  

Science.gov (United States)

Proper construction of the asphalt pavement is a prerequisite to developing a long lasting roadway that does not require extensive future maintenance. This goal is achieved by verifying that design specifications are met through the use of quality assurance (QA) practices. The in-situ density is regarded as one of the most important controls used to ensure that a pavement being placed is of high quality because it is a good indicator of future performance. In-situ density is frequently assessed utilizing one or more of the following three methods: cores, nuclear density gauge measurements or non-nuclear density gauge measurements. Each of the above mentioned methods, however, have their distinct disadvantages. Cores, for example, are generally considered to be the most accurate means of measuring in-situ density, however, they are a time consuming and destructive test that introduces a defect into asphalt pavements. Because of the destructive nature associated with coring, contractors and agencies have alternatively used non-destructive nuclear and non-nuclear density gauges for quality control purposes. These instruments allow for a more rapid assessment of the in-situ density, allowing measurements to be taken even during the pavement's construction. The disadvantage of these gauges are that they provide density readings only at discrete locations of the asphalt pavement mat, while no consensus exists among pavement researchers on the proper correlation between the gauges and core density. In recent years, numerous alternative methods have been introduced for the assessment of in-situ density, both during asphalt pavement construction and afterwards. These methods include, amongst others, intelligent compaction, thermal imaging and ground penetrating radar (GPR). Among these methods, GPR has been defined as both a technically feasible and promising method for the nondestructive, rapid, and continuous evaluation of in-situ asphalt pavement density based on electromagnetic mixing (EM) theory, through the utilization of proper models. These models enable the prediction of asphalt mixture density dependent on its bulk dielectric constant as measured by the GPR, the dielectric properties of the asphalt mix materials, as well as other material information. The goal of the present study is to attempt to verify the prediction performance of various density models. To accomplish this goal GPR surveys were carried out in the field during asphalt pavement construction to evaluate the density results due to different compaction modes. The GPR data was analyzed to calculate the appropriate asphalt mix dielectric properties needed for the activation of the considered density prediction models. Predicted densities were compared with densities of the field cores extracted from the as-built asphalt pavement prior to trafficking. It was found that the predicted density values were significantly lower when compared to the ground truth data. A further investigation of the effect of temperature on GPR readings showed that GPR seems to overestimate the in-situ density. However, this approach could be used effectively to evaluate the performance of different compaction methods and set up the compaction pattern that is needed to achieve the desired asphalt pavement density.

Plati, Christina; Georgiou, Panos; Loizos, Andreas

2013-04-01

400

Techno- Economical Study of Rigid Pavement by Using the Used Foundry Sand  

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Full Text Available Indian road network of almost 3.5 million km comprising both paved and unpaved surfaces is the world’s second largest. Indian roads are presently constructed with not the right choice of material. The two major types of materials, bitumen and concrete are used in road construction in the country. A very small share of roads in the country is made of concrete. Though, it is superior on many counts as a medium for road buildings. The use of large amount of by-product materials as powder or fines not only avoids the requirement of landfills but also reduce the environmental problems. It is most essential to develop profitable building materials from used foundry sand. The innovative use of used foundry sand in concrete formulations as a fine aggregate replacement material was tested as an alternative to traditional concrete. The fine aggregate has been replaced by used foundry sand accordingly in the range of 0%, 10%, 30% & 50% by weight for M-20 grade concrete. Concrete mixtures were produced, tested and compared in terms of compressive and flexural strength with the conventional concrete. These tests were carried out to evaluate the mechanical properties for 7, 14 and 28 days. This research work is to investigate the behaviour of concrete while replacing used foundry sand in different proportion in concrete. This low cost concrete with good strength is used in rigid pavement for 3000 commercial vehicles per day (cvpd and Dry Lean Concrete (DLC 100mm thick for national highway to make it eco-friendly.

Vipul D. Prajapati1 , Nilay Joshi2 , Prof. Jayeshkumar Pitroda

2013-05-01

401

A study of sound absorption by street canyon boundaries and asphalt rubber concrete pavement  

Science.gov (United States)

A sound field model, based on a classical diffusion equation, is extended to account for sound absorption in a diffusion parameter used to model sound energy in a narrow street canyon. The model accounts for a single sound absorption coefficient, separate accommodation coefficients and a combination of separate absorption and accommodation coefficients from parallel canyon walls. The new expressions are compared to the original formula through numerical simulations to reveal the effect of absorption on sound diffusion. The newly established analytical formulae demonstrate satisfactory agreement with their predecessor under perfect reflection. As well, the influence of the extended diffusion parameter on normalized sound pressure levels in a narrow street canyon is in agreement with experimental data. The diffusion parameters are used to model sound energy density in a street canyon as a function of the sound absorption coefficient of the street canyon walls. The acoustic and material properties of conventional and asphalt rubber concrete (ARC) pavement are also studied to assess how the crumb rubber content influences sound absorption in street canyons. The porosity and absolute permeability of compacted specimens of asphalt rubber concrete are measured and compared to their normal and random incidence sound absorption coefficients as a function of crumb rubber content in the modified binder. Nonlinear trends are found between the sound absorption coefficients, porosity and absolute permeability of the compacted specimens and the percentage of crumb rubber in the modified binders. The cross-sectional areas of the air voids on the surfaces of the compacted specimens are measured using digital image processing techniques and a linear relationship is obtained between the average void area and crumb rubber content. The measured material properties are used to construct an empirical formula relating the average porosity, normal incidence noise reduction coefficients and percentage of crumb rubber in the modified binder of the compacted specimens.

Drysdale, Graeme Robert

402

A statistical evaluation of soil and climatic parameters affecting the change in pavement deflection during thawing of subgrades  

Science.gov (United States)

This report analyzes the results of a field study previously reported by Scrivner et al. (1969) for the National Cooperative Highway Research Program. These authors studied the seasonal pavement deflection characteristics of 24 test sites on roads in service in regions with freezing indexes ranging from 100 F-days to 2100 F-days. They used the Dynaflect cyclic pavement loading device to determine the pavement system response. Of specific interest to my analysis was the increased pavement deflection after freezing and thawing and the time to recovery of normal deflection characteristics. These characteristics were related to soil and climatic factors using statistical techniques. The most significant observations of this statistical analysis are: (1) that the freezing index is not a significant parameter in determining the percent increase in pavement deflection during thawing, and (2) that the recovery time is inversely proportional to the depth of freezing. As was expected, the most significant variable affecting the increase in pavement deflection was the frost susceptibility classification. This observation reinforces the necessity for careful selection of soil materials used in pavement systems.

Chamberlain, E. J.

1981-07-01

403

Emotional distress in women presenting for breast imaging  

International Nuclear Information System (INIS)

The aim of this study was to assess anxiety and depression in a sample of women presenting for imaging of breast following a clinical referral. Emotional distress in the women was also assessed in relation to demographic factors, reason for referral, presence for breast symptoms, type of imaging procedure performed and self-reported pain and discomfort during imaging. The study comprised 167 patients. The Hopkins Symptom Checklist-25 (HSCL-25) and a discomfort rating scale were used to assess emotional distress and discomfort or pain experienced during the imaging. While less than 10% of all subjects scored above psychiatric cut-off points for anxiety and depression, 25% and 20% reported significant distress associated with anxiety and depression symptoms respectively. Education alone was associated with higher anxiety scores, while the presence of breast symptoms significantly increased depression scores and reports of specific nonsomatic symptoms of depression. Higher anxiety and depression scores were also associated with pain experienced during the imaging procedure. Emotional distress may negatively impact women's experience of breast imaging. Screening for emotional distress is important within the context of breast imaging. (author)

404

Addressing appearance-related distress across clinical conditions.  

Science.gov (United States)

Evidence is accumulating about the nature and prevalence of appearance-related distress across a variety of clinical populations. Health professionals working with specific patient groups are often aware of these difficulties and their detrimental effect on quality of life and wellbeing. However, many health professionals lack knowledge and skills on how to support patients, either within the team or via referral to relevant service providers who have expertise in managing appearance-related distress. This is mainly owing to a lack of information about screening, assessment measures and available interventions. The aim of this article is to consider how health professionals can support patients who experience distress as a result of living with a long-term physical health condition that has altered their appearance. This article summarises the challenges for patients and health professionals surrounding body image, altered appearance and associated distress. Gaps in relation to screening measures, differing types of intervention, appearance-related skills training for healthcare teams, care pathways and access to services are identified. A summary of the limited range of interventions currently available has been mapped onto a stepped model of care, ranging from self-help to intensive therapies. Finally, readers are pointed to helpful resources for understanding, identifying, addressing and signposting patients with appearance-related distress. PMID:23123892

Bessell, Alyson; Dures, Emma; Semple, Cherith; Jackson, Sue

405

Improvements to the materials characterization and fatigue life prediction methods of the Texas rigid pavement overlay design procedure  

Science.gov (United States)

Certain improvements to the Texas Rigid Pavement Overlay Procedure (RPOD2) with regard to materials characterization and fatigue life predictions are presented. Suggestions are made for characterizing rigid pavement layers from Dynaflect deflections and material tests, and some guidelines for selecting design sections along the length of a road are presented. Finite element analysis is used to quantify the effect of pavement discontinuities on the tresses obtained from layered theory. Further finite element analysis is used in an attempt to relate the critical reflection stresses in an ac overlay to deflection measurements obtained before overlaying.

Taute, A.; McCullough, B. F.; Hudon, W. R.

1981-11-01

406

Assessment of the performance of rigid pavement back-calculation through finite element modeling  

Science.gov (United States)

This study focuses on examining the behavior of rigid pavement layers during the Falling Weight Deflectometer (FWD) test. Factors affecting the design of a concrete slab, such as whether the joints are doweled or undoweled and the spacing between the transverse joints, were considered in this study. Explicit finite element analysis was employed to investigate pavement layers' responses to the action of the impulse of the FWD test. Models of various dimensions were developed to satisfy the factors under consideration. The accuracy of the finite element models developed in this investigation was verified by comparing the finite element- generated deflection basin with that experimentally measured during an actual test. The results showed that the measured deflection basin can be reproduced through finite element modeling of the pavement structure. The resulting deflection basins from the use FE modeling was processed in order to backcalculate pavement layer moduli. This approach provides a method for the evaluation of the performance of existing backcalculation programs which are based on static elastic layer analysis. Based upon the previous studies conducted for the selection of software, three different backcalculation programs were chosen for the evaluation: MODULUS5.0, EVERCALC4.0, and MODCOMP3. The results indicate that ignoring the dynamic nature of the load may lead to crude results, especially during backcalculation procedures.

Shoukry, Samir N.; William, Gergis W.; Martinelli, David R.

1999-02-01

407

Hydrologic and Pollutant Removal Performance of a Full-Scale, Fully Functional Permeable Pavement Parking Lot  

Science.gov (United States)

In accordance with the need for full-scale, replicated studies of permeable pavement systems used in their intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage conditions, and maintenance regimes to evaluate these systems, the EPA?s Urb...

408

Monitoring of the permeable pavement demonstration site at Edison Environmental Center  

Science.gov (United States)

The EPA?s Urban Watershed Management Branch has installed an instrumented, working full-scale 110-space pervious pavement parking lot and has been monitoring several environmental stressors and runoff. This parking lot demonstration site has allowed the investigation of differenc...

409

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

Directory of Open Access Journals (Sweden)

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.

Alaa H. Abed

2012-01-01

410

Stomatal and pavement cell density linked to leaf internal CO2 concentration.  

Czech Academy of Sciences Publication Activity Database

Ro?. 114, ?. 2 (2014), s. 191-202. ISSN 0305-7364 R&D Projects: GA ?R(CZ) GAP501/12/1261 Institutional support: RVO:60077344 Keywords : Stomata l density * Stomata development * Pavement cells Subject RIV: CE - Biochemistry Impact factor: 3.295, year: 2013

Šantr??ek, Ji?í; Vráblová, M.; Šimková, Marie; Hronková, Marie; Drtinová, M.; Kv?to?, J.; Vrábl, D.; Kubásek, J.; Macková, J.; Wiesnerová, Dana; Neuwithová, J.; Schreiber, L.

2014-01-01

411

Investigation of Primary Causes of Load-Related Cracking in Asphalt Concrete Pavement in North Carolina  

Science.gov (United States)

This dissertation presents causes of cracking in asphalt concrete pavement in North Carolina through field investigation and laboratory experiments with field extracted material. North Carolina is experiencing higher than anticipated rates of fatigue cracking compared to other state. These higher than expected rates could be reflective of the national trends in mix design practice or could be caused by structural pavement failures. The problems associated with premature cracking in North Carolina pavements point to the need to evaluate the North Carolina Department of Transportation (NCDOT) mixes, processes, and measures to ensure that these factors properly balance the goals of preventing cracking and minimizing permanent deformation. Without solid data from in-service pavements, any conclusions regarding the causes of these failures might be pure conjecture. Accordingly, this research examines material properties through laboratory experiments using field-extracted materials and investigates in situ pavements and pavement structure. In order to assess condition of existing pavement, alligator cracking index (ACI) was developed. The asphalt content in the top layer that exhibits top-down cracking or bottom-up cracking has a proportional relationship to ACI values. The air void content in a bottom layer that exhibits top-down cracking or bottom-up cracking shows an inverse proportional relationship to ACI values. These observations reflect reasonable results. A comparison between ACI and asphalt film thickness values does not produce noteworthy findings, but somewhat reasonable results are evident once the range of comparison is narrowed down. Thicker film thicknesses show higher ACI values. From field core visual observations, road widening is identified as a major cause of longitudinal cracking. Regions with observed layer interface separation tend to have low ACI values. Through tensile strain simulation based on actual field conditions, it is observed that sites with observed bottom-up cracking have higher tensile strain levels at the bottom of the asphalt layer than sites with observed top-down cracking. Extracted binder fatigue test results indicate that binder properties between good and poor sections of a given site are not the result of differences in the binder properties. Hence, other mixture design factors are at work in controlling the site variability in terms of fatigue resistance.

Park, Hong Joon

412

Acute respiratory distress syndrome: the Berlin Definition.  

Science.gov (United States)

The acute respiratory distress syndrome (ARDS) was defined in 1994 by the American-European Consensus Conference (AECC); since then, issues regarding the reliability and validity of this definition have emerged. Using a consensus process, a panel of experts convened in 2011 (an initiative of the European Society of Intensive Care Medicine endorsed by the American Thoracic Society and the Society of Critical Care Medicine) developed the Berlin Definition, focusing on feasibility, reliability, validity, and objective evaluation of its performance. A draft definition proposed 3 mutually exclusive categories of ARDS based on degree of hypoxemia: mild (200 mm Hg < PaO2/FIO2 ? 300 mm Hg), moderate (100 mm Hg < PaO2/FIO2 ? 200 mm Hg), and severe (PaO2/FIO2 ? 100 mm Hg) and 4 ancillary variables for severe ARDS: radiographic severity, respiratory system compliance (?40 mL/cm H2O), positive end-expiratory pressure (?10 cm H2O), and corrected expired volume per minute (?10 L/min). The draft Berlin Definition was empirically evaluated using patient-level meta-analysis of 4188 patients with ARDS from 4 multicenter clinical data sets and 269 patients with ARDS from 3 single-center data sets containing physiologic information. The 4 ancillary variables did not contribute to the predictive validity of severe ARDS for mortality and were removed from the definition. Using the Berlin Definition, stages of mild, moderate, and severe ARDS were associated with increased mortality (27%; 95% CI, 24%-30%; 32%; 95% CI, 29%-34%; and 45%; 95% CI, 42%-48%, respectively; P < .001) and increased median duration of mechanical ventilation in survivors (5 days; interquartile [IQR], 2-11; 7 days; IQR, 4-14; and 9 days; IQR, 5-17, respectively; P < .001). Compared with the AECC definition, the final Berlin Definition had better predictive validity for mortality, with an area under the receiver operating curve of 0.577 (95% CI, 0.561-0.593) vs 0.536 (95% CI, 0.520-0.553; P < .001). This updated and revised Berlin Definition for ARDS addresses a number of the limitations of the AECC definition. The approach of combining consensus discussions with empirical evaluation may serve as a model to create more accurate, evidence-based, critical illness syndrome definitions and to better inform clinical care, research, and health services planning. PMID:22797452

Ranieri, V Marco; Rubenfeld, Gordon D; Thompson, B Taylor; Ferguson, Niall D; Caldwell, Ellen; Fan, Eddy; Camporota, Luigi; Slutsky, Arthur S

2012-06-20

413

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

Science.gov (United States)

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, ?PAH 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 ?PAH 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.

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

2010-12-01

414

Ground surface temperature simulation for different land covers  

Science.gov (United States)

SummaryA model for predicting temperature time series for dry and wet land surfaces is described, as part of a larger project to assess the impact of urban development on the temperature of surface runoff and coldwater streams. Surface heat transfer processes on impervious and pervious land surfaces were investigated for both dry and wet weather periods. The surface heat transfer equations were combined with a numerical approximation of the 1-D unsteady heat diffusion equation to calculate pavement and soil temperature profiles to a depth of 10 m. Equations to predict the magnitude of the radiative, convective, conductive and evaporative heat fluxes at a dry or wet surface, using standard climate data as input, were developed. A model for the effect of plant canopies on surface heat transfer was included for vegetated land surfaces. Given suitable climate data, the model can simulate the land surface and sub-surface temperatures continuously throughout a six month time period or for a single rainfall event. Land surface temperatures have been successfully simulated for pavements, bare soil, short and tall grass, a forest, and two agricultural crops (corn and soybeans). The simulations were run for three different locations in US, and different years as imposed by the availability of measured soil temperature and climate data. To clarify the effect of land use on surface temperatures, the calibrated coefficients for each land use and the same soil coefficients were used to simulate surface temperatures for a six year climate data set from Albertville, MN. Asphalt and concrete give the highest surface temperatures, as expected, while vegetated surfaces gave the lowest. Bare soil gives surface temperatures that lie between those for pavements and plant-covered surfaces. The soil temperature model predicts hourly surface temperatures of bare soil and pavement with root-mean-square errors (RMSEs) of 1-2 °C, and hourly surface temperatures of vegetation-covered surfaces with RMSEs of 1-3 °C.

Herb, William R.; Janke, Ben; Mohseni, Omid; Stefan, Heinz G.

2008-07-01

415

Moral distress and its correlates among mental health nurses in Jordan.  

Science.gov (United States)

Moral distress has received much attention in international nursing published work in recent years. However, in the published work, little is known about the moral distress of mental health nurses. The aims of this study were to examine the intensity level of moral distress, to identify the best predictors of moral distress, and to examine relationships of moral distress with burnout, job satisfaction, intention to leave the current job, and both demographic and work-related variables of that group. Employing a descriptive correlational cross-section design and a convenience sampling method, data were collected using the Moral Distress Scale for Psychiatric Nurses, Maslach Burnout Inventory, and Job Satisfaction Scale from 130 Jordanian mental health nurses working in the largest psychiatric hospital in Jordan. Results showed that the intensity level of moral distress was found to be moderately high, especially in an 'unethical conduct by caregivers' subscale. Age, income level, nurses' years of experience, and caseloads correlated significantly and negatively with moral distress, while educational level and intention to leave the current job correlated significantly and positively with moral distress. Interestingly, job satisfaction did not significantly correlate with moral distress. Income level, caseloads, burnout level, attending workshops in mental health, and educational level were the best predictors of moral distress. More studies on moral distress and continuing educational interventional programs aimed at minimizing the levels of moral distress and burnout at institutional and individual level are required. PMID:23320816

Hamaideh, Shaher H

2014-02-01

416

Patterns of gender equality at workplaces and psychological distress.  

Science.gov (United States)

Research in the field of occupational health often uses a risk factor approach which has been criticized by feminist researchers for not considering the combination of many different variables that are at play simultaneously. To overcome this shortcoming this study aims to identify patterns of gender equality at workplaces and to investigate how these patterns are associated with psychological distress. Questionnaire data from the Northern Swedish Cohort (n?=?715) have been analysed and supplemented with register data about the participants' workplaces. The register data were used to create gender equality indicators of women/men ratios of number of employees, educational level, salary and parental leave. Cluster analysis was used to identify patterns of gender equality at the workplaces. Differences in psychological distress between the clusters were analysed by chi-square test and logistic regression analyses, adjusting for individual socio-demographics and previous psychological distress. The cluster analysis resulted in six distinctive clusters with different patterns of gender equality at the workplaces that were associated to psychological distress for women but not for men. For women the highest odds of psychological distress was found on traditionally gender unequal workplaces. The lowest overall occurrence of psychological distress as well as same occurrence for women and men was found on the most gender equal workplaces. The results from this study support the convergence hypothesis as gender equality at the workplace does not only relate to better mental health for women, but also more similar occurrence of mental ill-health between women and men. This study highlights the importance of utilizing a multidimensional view of gender equality to understand its association to health outcomes. Health policies need to consider gender equality at the workplace level as a social determinant of health that is of importance for reducing differences in health outcomes for women and men. PMID:23326404

Elwér, Sofia; Harryson, Lisa; Bolin, Malin; Hammarström, Anne

2013-01-01

417

Stabilized fiber-reinforced pavement base course with recycled aggregate  

Science.gov (United States)

This study evaluates the benefits to be gained by using a composite highway base course material consisting of recycled crushed concrete aggregate, portland cement, fly ash, and a modest amount of reinforcing fibers. The primary objectives of this research were to (a) quantify the improvement that is obtained by adding fibers to a lean concrete composite (made from recycled aggregate and low quantities of Portland cement and/or fly ash), (b) evaluate the mechanical behavior of such a composite base course material under both static and repeated loads, and (c) utilize the laboratory-determined properties with a mechanistic design method to assess the potential advantages. The split tensile strength of a stabilized recycled aggregate base course material was found to be exponentially related to the compacted dry density of the mix. A lean mix containing 4% cement and 4% fly ash (by weight) develops sufficient unconfined compressive, split tensile, and flexural strengths to be used as a high quality stabilized base course. The addition of 4% (by weight) of hooked-end steel fibers significantly enhances the post-peak load-deformation response of the composite in both indirect tension and static flexure. The flexural fatigue behavior of the 4% cement-4% fly ash mix is comparable to all commonly used stabilized materials, including regular concrete; the inclusion of 4% hooked-end fibers to this mix significantly improves its resistance to fatigue failure. The resilient moduli of stabilized recycled aggregate in flexure are comparable to the values obtained for traditional soil-cement mixes. In general, the fibers are effective in retarding the rate of fatigue damage accumulation, which is quantified in terms of a damage index defined by an energy-based approach. The thickness design curves for a stabilized recycled aggregate base course, as developed by using an elastic layer approach, is shown to be in close agreement with a theoretical model (based on Westergaard's assumptions for rigid pavements), which has been found to explain reasonably well the field behavior of unreinforced and fiber-reinforced concrete slabs on grade. Finally, a preliminary cost analysis demonstrated that the use of stabilized recycled aggregate instead of a standard crushed stone base course can result in a meaningful economic savings.

Sobhan, Khaled

418

Perceived Discrimination and Psychological Distress of Myanmar Refugees in Malaysia  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this research is to explore the psychological distress and discrimination experienced by refugees from Myanmar in Malaysia. A narrative inquiry approach and an in depth interview were chosen to get in touch with the social world of the refugees. Bronfenbrenner’s (1979 ecological theory was used to examine the psychological distress of the participants in their social context. The findings revealed the social, economical and psychological discrimination experienced by these refugees while waiting for the opportunity to be relocated to a new country.

Sew Kim Low

2014-05-01

419

Mental distress and social conditions and lifestyle in northern Norway.  

OpenAIRE

In a cross sectional survey of risk factors for coronary heart disease three questions about mental distress were included in a questionnaire completed by 13,704 people, 64% of the total population aged 20-54 in one municipality. Overall, 860 (12.5%) of the men and 1141 (16.8%) of the women reported having at least one symptom of mental distress. There were no distinct differences between the age groups. Single people, separated and divorced people, and those who reported that the financial s...

Hansen, V.; Jacobsen, B. K.

1989-01-01

420

[The Life Style Index: correlations with psychological distress and hostility].  

Science.gov (United States)

The Life Style Index (LSI) was designed to assess defense mechanisms, assuming that their use is related to specific emotional states and diagnostic concepts. Aiming to further investigate the psychometric properties of the Greek version of the LSI, the aim of the present study was to investigate the relationship of specific defense mechanisms with dimensions of psychological distress and hostility features in three different populations. The sample comprised 1261 adults (410 healthy participants, 723 medical patients and 128 psychiatric patients). Along with defense mechanisms (LSI), Psychological Distress (General Health Questionnaire, GHQ-28) and Hostility features (Hostility and Direction of Hostility Questionnaire, HDHQ) were also assessed. The results showed that increased psychological distress is related with increased use of all defenses except Denial, with which psychological distress is negatively associated. Regression is constantly related with psychological distress and differentiates psychiatric patients from the other groups of participants, while Compensation and Reaction Formation are related to depressive symptomatology. In medical patients, Repression was found to increase the physical dimension of psychological distress and the social dysfunction. On the contrary,Denial was negatively associated with these dimensions of psychological distress. In the psychiatric patient and healthy participant samples, Projection plays the most detrimental role. Regarding hostility and direction of hostility, those who were found to introvert their hostility presented with higher scores in Denial, indicating that they possibly 'deny' their hostility, and the degree of the Denial was found to be negatively associated with the degree of Introverted Hostility. Those who directed their hostility towards the others, presented with higher rates of Projection, while neither Denial nor Reaction Formation seemed sufficient enough to temper the degree of Extroverted Hostility. In conclusion,the present results strengthen further the validity of the Greek version of the LSI and provide additional evidence about the relation of defence mechanisms with dimensions of psychological distress and the direction of hostility in different populations, indicating that the empirical assessment of defense mechanisms can contribute significantly in the study of the factors that mediate or moderate the course or the outcome of medical or psychiatric disorders. PMID:21971196

Hyphantis, T; Floros, G D; Goulia, P; Iconomou, G; Assimakopoulos, K

2011-01-01

421

Successful Solutions to SSME/AT Development Turbine Blade Distress  

Science.gov (United States)

As part of the High-Pressure Fuel Turbopump/Alternate Turbopump (HPFTP/AT) turbine blade development program, unique turbine blade design features were implemented to address 2nd stage turbine blade high cycle fatigue distress and improve turbine robustness. Features included the addition of platform featherseal dampers, asymmetric blade tip seal segments, gold plating of the blade attachments, and airfoil tip trailing edge modifications. Development testing shows these features have eliminated turbine blade high cycle fatigue distress and consequently these features are currently planned for incorporation to the flight configuration. Certification testing will begin in 1999. This presentation summarizes these features.

Montgomery, Stuart K.

1999-01-01

422

Development of test method for evaluating root resistance of pavement used for roof garden caused by thickening growth of root  

Energy Technology Data Exchange (ETDEWEB)

The growth of roots of plants can damage roof garden components, such as pavements. This paper developed a test method for evaluating the resistance of pavement used in roof gardens to damage from a thickening growth of roots. The study assessed the behaviour of plant roots and evaluated the force of root growth subjected to hypertrophy. A system to measure the enlargement force of roots was designed and used for measurements over a period of 8 months on a cherry blossom of 21 years growth. The enlargement force was approximately 440 N/cm. A mechanical simulated root was designed and used to carry out experimental tests on asphalt pavements. The tests results demonstrated the viability of simulated root for evaluation of root resistances in pavements and various components of roof gardens.

Ishihara, Saori; Tanaka, Kyoji [Tokyo Institute of Technology, Tokyo, (Japan)

2010-07-01

423

47 CFR 73.4140 - Minority ownership; tax certificates and distress sales.  

Science.gov (United States)

...2010-10-01 false Minority ownership; tax certificates and distress sales. 73.4140 Section 73.4140 Telecommunication...Stations § 73.4140 Minority ownership; tax certificates and distress sales. (a) See Public Notice, FCC...

2010-10-01

424

Effects of reclaimed asphalt pavement on indirect tensile strength test of foamed asphalt mix tested in dry condition  

International Nuclear Information System (INIS)

Indirect tensile strength (ITS) test was conducted to analyse strength of the foamed asphalt mixes incorporating reclaimed asphalt pavement. Samples were tested for ITS after cured in the oven at 40°C for 72 hours. This testing condition known as dry condition or unconditioned. Laboratory results show that reclaimed asphalt pavement (RAP) contents insignificantly affect the ITS results. ITS results significantly affected by foamed bitumen contents.

425

BENCHMARKING INCIDENCE OF DISTRESS IN THE NIGERIAN BANKING INDUSTRY ON ALTMAN SCALE  

OpenAIRE

This paper applied the Altman’s model in the prediction of distress in the Nigerian bankingindustry. Three banks (Union bank, Bank PHB and Intercontinental Bank) declared distress duringthe period of the study were used as case studies. Four years financial statistics prior to distress wasused to compute the most discriminating financial ratios that were substituted into the Altman’smodel. The result of the analysis shows that Altman’s model significantly predicted the distress stateof ...

Oforegbunam Thaddeus Ebiringa

2011-01-01

426

Multiple States of Financially Distressed Companies : Tests using a Competing-risks Model  

OpenAIRE

This study examines the determinants of multiple states of financial distress by applying a competing-risksmodel. It investigates the effect of financial ratios, market-based variables and company-specific variables,including company age, size and squared size on three different states of corporate financial distress: activecompanies; distressed external administration companies; and distressed takeover, merger or acquisitioncompanies. A sample of 1,081 publicly listed Australian non-financia...

Nongnit Chancharat; Gary Tian; Pamela Davy; Michael McCrae; Sudhir Lodh

2010-01-01

427

Psychological Distress among Nursing, Physiotherapy and Occupational Therapy Students: A Longitudinal and Predictive Study  

Science.gov (United States)

In this study, we present longitudinal data on changes in psychological distress among 232 Norwegian undergraduate students of nursing, physiotherapy, and occupational therapy. Psychological distress was assessed by applying the 12-item version of the General Health Questionnaire. Nursing students became substantially more distressed during the…

Nerdrum, Per; Rustoen, Tone; Helge Ronnestad, Michael

2009-01-01

428

A Comparison of High- and Low-Distress Marriages that End in Divorce  

Science.gov (United States)

We used data from Waves 1 and 2 of the National Survey of Families and Households to study high- and low-distress marriages that end in divorce. A cluster analysis of 509 couples who divorced between waves revealed that about half were in high-distress relationships and the rest in low-distress relationships. These 2 groups were not artifacts of…

Amato, Paul R.; Hohmann-Marriott, Bryndl

2007-01-01

429

Late Financial Distress Process Stages and Financial Ratios : Evidence for Auditors' Goingconcern Evaluation  

DEFF Research Database (Denmark)

The present study adds to our understanding and knowledge of financial distress predictions regarding the usefulness of financial ratios in the late stages of the financial distress process. The study contributes to previous research by generating information concerning: (1) the behavior and usefulness of single financial ratios in short-term financial distress prediction when the effect of each different financial distress process stage is considered; (2) the effects of recognition of the financial distress process stage on the financial distress prediction model. The time horizon for prediction is less than one year, and the empirical data consist of financial statement information from 106 distressed firms undergoing reorganization and their matched counterparts for 2003-2007. To analyze the effects of the specific distress process stage, the sample has been divided into two groups according to the date of application for reorganization: the first group of businesses applied for reorganization between 1 and 182 days after the closing of accounts, and the second group between 183 and 365 days after that point. The study findings provide evidence that the financial distress process stage affects the classification ability of single financial ratios and financial distress prediction models in short-term financial distress prediction. The study shows that the auditor's GC task could be supported by paying attention to the financial distress process stage. The implications of these findings for auditors and every stakeholder of business firms are considered.

Sormunen, Nina; Laitinen, Teija

2012-01-01

430

Oxytocin reduces separation distress in piglets when given intranasally  

Science.gov (United States)

Oxytocin (OT) is one of the neurobiological foundations of sociality. It acts as a neuropeptide in numerous social processes, from ultra-social to anti-social behaviors. Evidence supports a role for OT in social support, possibly by attenuating separation distress. Nonetheless, research on OT is lac...

431

46 CFR 117.68 - Distress flares and smoke signals.  

Science.gov (United States)

...2010-10-01 2010-10-01 false Distress flares and smoke...limited coastwise, and Great Lakes routes. A vessel on...the Commandant. (b) Lakes, bays, and sounds, and rivers routes. A vessel on a lakes, bays, and sounds, or...

2010-10-01

432

46 CFR 180.68 - Distress flares and smoke signals.  

Science.gov (United States)

...2010-10-01 2010-10-01 false Distress flares and smoke...limited coastwise, and Great Lakes routes. A vessel on...the Commandant. (b) Lakes, bays, and sounds, and rivers routes. A vessel on a lakes, bays, and sounds, or...

2010-10-01

433