Science.gov

Sample records for flexible pavement performance

  1. Evaluation of flexible pavement performance life in Florida. Final research report, October 1993--June 1998

    SciTech Connect

    Ping, W.V.; He, Y.

    1998-06-01

    The pavement performance life provides information on how long a particular pavement type will typically last before it needs rehabilitation. This study presents the research effort to estimate the average flexible pavement performance life in Florida. Two data files of Pavement Condition Survey (PCS) and Work Program Administration (WPA) were used for this study. SAS programs were applied to analyze and manipulate these two data files. The pavement performance condition curves were developed for a large sample size of pavement sections based on the polynomial model. The average pavement performance lives were evaluated for each pavement group based on the performance curves. The results of the evaluation showed that the primary system had longer average performance life than the interstate system. Generally, the polynomial model performed well in fitting the data. The pavement performance curve indicates that if M and R are performed while the pavement is still in the `slow rate of deterioration` phase, life cycle cost may be reduced.

  2. Performance of a movable flexible pipe-encapsulated FBG sensor developed for shape monitoring of multi-layered pavement structure

    NASA Astrophysics Data System (ADS)

    Wang, Huaping; Liu, Wanqiu; Zhou, Zhi

    2014-03-01

    The large span and heterogeneous components of multi-layered pavement structure usually bring about stochastic damage, and many modern approaches, such as ground penetrating radar, integral imaging and optical fiber sensing technology, have been employed to detect the degeneration mechanism. Restricted by the cost and universality, novel elements for pavement monitoring are in high demand. Optical fiber sensing technology for high sensitivity, long stability, anti-corrosion and resistance to water erosion then is considered. Therefore, a movable FBG sensor located in flexible pipe is developed, which has long stroke inside inner wall of the hollow pipe, and a full-scale shape of the structure could be sketched just with one FBG. Theoretical and experimental methods about establishing the relationship between wavelength variable and curvature have been provided, and function about reconfiguring the coordinate is converted to a mathematic question. Move over, transfer error modification has been taken into account for modify related error. Multi-layered pavement model embedded with this sensor will be accomplished to inspect its performance in later work. The work in the paper affords a feasible method for shape monitoring and would be potentially valuable for the maintenance and inverse design of pavement structure.

  3. Teaching Methodology of Flexible Pavement Materials and Pavement Systems

    ERIC Educational Resources Information Center

    Mehta, Yusuf; Najafi, Fazil

    2004-01-01

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

  4. Geotextiles in Flexible Pavement Construction

    ERIC Educational Resources Information Center

    Alungbe, Gabriel D.

    2004-01-01

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

  5. Geotextiles in Flexible Pavement Construction

    ERIC Educational Resources Information Center

    Alungbe, Gabriel D.

    2004-01-01

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

  6. Effects of temperature and water on pavement performance

    SciTech Connect

    Badu-Tweneboah, K.; Tia, M.; Ruth, B.E.; Richardson, J.M.; Armaghani, J.M.

    1987-01-01

    The 12 papers in the report deal with the following areas: procedures for estimation of asphalt-concrete pavement moduli at in-situ temperatures; stress caused by temperature gradient in portland-cement concrete pavements; characterizing temperature effects for pavement analysis and design; temperature response of concrete pavements; an examination of environmental versus load effects on pavements; moisture in portland-cement concrete; effect of rainfall on the performance of continuously reinforced concrete pavements in Texas; effect of moisture on the structural performance of a crushed-limestone road base; water-induced distress in flexible pavement in a wet tropical climate; an evaluation of design high-water clearances for pavements; economic impact of pavement subsurface drainage; use of open-graded, free-draining layers in pavement systems; a national synthesis report.

  7. Analysis and design optimization of flexible pavement

    SciTech Connect

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

    2000-04-01

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

  8. Evaluation of base widening methods on flexible pavements in Wyoming

    NASA Astrophysics Data System (ADS)

    Offei, Edward

    The surface transportation system forms the biggest infrastructure investment in the United States of which the roadway pavement is an integral part. Maintaining the roadways can involve rehabilitation in the form of widening, which requires a longitudinal joint between the existing and new pavement sections to accommodate wider travel lanes, additional travel lanes or modification to shoulder widths. Several methods are utilized for the joint construction between the existing and new pavement sections including vertical, tapered and stepped joints. The objective of this research is to develop a formal recommendation for the preferred joint construction method that provides the best base layer support for the state of Wyoming. Field collection of Dynamic Cone Penetrometer (DCP) data, Falling Weight Deflectometer (FWD) data, base samples for gradation and moisture content were conducted on 28 existing and 4 newly constructed pavement widening projects. A survey of constructability issues on widening projects as experienced by WYDOT engineers was undertaken. Costs of each joint type were compared as well. Results of the analyses indicate that the tapered joint type showed relatively better pavement strength compared to the vertical joint type and could be the preferred joint construction method. The tapered joint type also showed significant base material savings than the vertical joint type. The vertical joint has an 18% increase in cost compared to the tapered joint. This research is intended to provide information and/or recommendation to state policy makers as to which of the base widening joint techniques (vertical, tapered, stepped) for flexible pavement provides better pavement performance.

  9. The effect of loading time on flexible pavement dynamic response: a finite element analysis

    NASA Astrophysics Data System (ADS)

    Yin, Hao; Solaimanian, Mansour; Kumar, Tanmay; Stoffels, Shelley

    2007-12-01

    Dynamic response of asphalt concrete (AC) pavements under moving load is a key component for accurate prediction of flexible pavement performance. The time and temperature dependency of AC materials calls for utilizing advanced material characterization and mechanistic theories, such as viscoelasticity and stress/strain analysis. In layered elastic analysis, as implemented in the new Mechanistic-Empirical Pavement Design Guide (MEPDG), the time dependency is accounted for by calculating the loading times at different AC layer depths. In this study, the time effect on pavement response was evaluated by means of the concept of “pseudo temperature.” With the pavement temperature measured from instrumented thermocouples, the time and temperature dependency of AC materials was integrated into one single factor, termed “effective temperature.” Via this effective temperature, pavement responses under a transient load were predicted through finite element analysis. In the finite element model, viscoelastic behavior of AC materials was characterized through relaxation moduli, while the layers with unbound granular material were assumed to be in an elastic mode. The analysis was conducted for two different AC mixtures in a simplified flexible pavement structure at two different seasons. Finite element analysis results reveal that the loading time has a more pronounced impact on pavement response in the summer for both asphalt types. The results indicate that for reasonable prediction of dynamic response in flexible pavements, the effect of the depth-dependent loading time on pavement temperature should be considered.

  10. Structural response of LVR flexible pavements at Mn/ROAD project

    SciTech Connect

    Garg, N.; Thompson, M.R.

    1999-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Jayakumar, M.; Chee Soon, Lee

    2015-04-01

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

  12. The impact of material characteristics on tire pavement interaction noise for flexible pavements

    NASA Astrophysics Data System (ADS)

    Kocak, Salih

    Noise pollution has recently been one of the growing problems all over the world. While there are many sources of the noise, traffic noise is the main contributor to the total environmental noise. Although there are different sources for traffic noise, the tire pavement interaction noise is the most dominant component within most city and highway limits. One of the ways to reduce the tire pavement noise is to improve the material characteristics of the pavements such that they produce less noise. In this study, the relationship between basic material characteristics (e.g., Hot Mix Asphalt (HMA) volumetrics) and sound generation and absorption characteristics of flexible pavements was investigated. In addition, the effect of linear visco-elastic properties (e.g., dynamic modulus (|E*|) and phase angle (delta)) on sound absorption was studied. In order to focus only on impact of material characteristics and overshadow the effect of surface texture, a novel laboratory tire pavement noise measurement simulator (TIPANOS) was developed. The statistical analysis results showed that although the individual material characteristics do not have appreciable influence on sound absorption, there is a significant correlation between sound pressure levels (SPL) and combination of several material and linear visco-elastic parameters.

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

    NASA Astrophysics Data System (ADS)

    Kowalski, Karol J.

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

  14. Re-Evaluation of the AASHTO-Flexible Pavement Design Equation with Neural Network Modeling

    PubMed Central

    Tiğdemir, Mesut

    2014-01-01

    Here we establish that equivalent single-axle loads values can be estimated using artificial neural networks without the complex design equality of American Association of State Highway and Transportation Officials (AASHTO). More importantly, we find that the neural network model gives the coefficients to be able to obtain the actual load values using the AASHTO design values. Thus, those design traffic values that might result in deterioration can be better calculated using the neural networks model than with the AASHTO design equation. The artificial neural network method is used for this purpose. The existing AASHTO flexible pavement design equation does not currently predict the pavement performance of the strategic highway research program (Long Term Pavement Performance studies) test sections very accurately, and typically over-estimates the number of equivalent single axle loads needed to cause a measured loss of the present serviceability index. Here we aimed to demonstrate that the proposed neural network model can more accurately represent the loads values data, compared against the performance of the AASHTO formula. It is concluded that the neural network may be an appropriate tool for the development of databased-nonparametric models of pavement performance. PMID:25397962

  15. Re-evaluation of the AASHTO-flexible pavement design equation with neural network modeling.

    PubMed

    Tiğdemir, Mesut

    2014-01-01

    Here we establish that equivalent single-axle loads values can be estimated using artificial neural networks without the complex design equality of American Association of State Highway and Transportation Officials (AASHTO). More importantly, we find that the neural network model gives the coefficients to be able to obtain the actual load values using the AASHTO design values. Thus, those design traffic values that might result in deterioration can be better calculated using the neural networks model than with the AASHTO design equation. The artificial neural network method is used for this purpose. The existing AASHTO flexible pavement design equation does not currently predict the pavement performance of the strategic highway research program (Long Term Pavement Performance studies) test sections very accurately, and typically over-estimates the number of equivalent single axle loads needed to cause a measured loss of the present serviceability index. Here we aimed to demonstrate that the proposed neural network model can more accurately represent the loads values data, compared against the performance of the AASHTO formula. It is concluded that the neural network may be an appropriate tool for the development of databased-nonparametric models of pavement performance. PMID:25397962

  16. Performance of continuously reinforced concrete pavements: Volume 6 -- CRC pavement design, construction, and performance. Final report, August 1990--December 1994

    SciTech Connect

    Zollinger, D.G.; Buch, N.; Xin, D.; Soares, J.

    1999-02-01

    This report is one of a series of reports prepared as part of a recent study sponsored by the Federal Highway Administration (FHWA) aimed at updating the state-of-the-art of the design, construction, maintenance, and rehabilitation of continuous reinforced concrete (CRC) pavements. The scope of work of the FHWA study included the following: (1) Conduct of a literature review and preparation of an annotated bibliography on CRC pavements and CRC overlays. (2) Conduct of a field investigation and laboratory testing related to 23 existing in-service pavement sections. This was done to evaluate the effect of various design features on CRC pavement performance, to identify any design or construction related problems, and to recommend procedures to improve CRC pavement technology. (3) Evaluation of the effectiveness of various maintenance and rehabilitation strategies for CRC pavements. (4) Preparation of a Summary Report on the current state of the practice for CRC pavements. Each of the above four items is addressed in a separate report. The following reports have been prepared under this study: Performance of CRC Pavements. Volume 1: Summary of Practice and Annotated Bibliography. Volume 2: Field Investigation of CRC Pavements. Volume 3: Analysis and Evaluation of Field Test Data. Volume 4: Resurfacing for CRC Pavements. Volume 5: Maintenance and Repair of CRC Pavements. Volume 6: CRC Pavement Design, Construction, and Performance. Volume 7: Summary. This report is Volume 6 in the series.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  18. Two-dimensional finite element analysis of flexible pavements considering non-linear materials and interface conditions

    SciTech Connect

    Gonzales, C.R.; Salami, M.R.

    1995-06-01

    Two-dimensional finite element analysis of a flexible pavement section was performed using a special purpose finite element method (FEM) code and a commercial general purpose FEM. Viscoelastic, plastic, and hyperbolic-elastic materials models were used in the analyses. One-dimensional interface elements were used in both analyses. The results of the analyses were compared with predictions using current evaluation/design models.

  19. Monitoring the performance of geosynthetic materials within pavement systems using MEMS

    NASA Astrophysics Data System (ADS)

    Attoh-Okine, Nii O.; Ayenu-Prah, Albert Y.; Mensah, Stephen A.

    2005-05-01

    Geosynthetic materials have found useful applications when unbound aggregates have been placed on cohesive soil with very weak subgrade. They have also been successfully used in retarding reflective cracking in both flexible and composite pavements. There are many applications of geosynthetics in pavement engineering yet there is considerable lack of understanding in the behavior of the material. Geosynthetic materials exhibit very peculiar properties in the area of tensile strength and reinforcement. MEMS are miniature sensing or actuating devices that can interact with other environments (provided no adverse reaction occurs) to either obtain information or alter it. With remote query capability, it appears such devices can be embedded in pavement systems as testing and monitoring tools. The aim of this paper is to propose both field and laboratory methods for monitoring geotextile performance using MEMS.

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

    PubMed Central

    Karim, Mohamed Rehan; Khodaii, Ali; Almasi, Mohammad Hadi

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

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

  3. Statistical methods for pavement performance curve building, historical analysis, data sampling and storage. Final report, May 1997--July 1998

    SciTech Connect

    Zimmerman, K.A.; Bahulkar, A.M.

    1998-08-01

    The use of a pavement management system provides a state highway agency with the tools necessary to conduct a multi-year analysis of the maintenance and rehabilitation needs within the state based on both current needs and expected future conditions. In order to adequately predict future conditions, pavement performance models must be developed to reflect the deterioration trends of the agency`s pavements. At the time the SDDOT pavement management system was implemented in 1994, the Department developed a new condition rating system to evaluate the existing conditions of the state maintained pavements. At the same time, expert-based pavement performance models were developed to approximate the deterioration patterns of the highways based on pavement families (groupings of pavements with similar characteristics). A recommendation from that study (SD93-14) was to update the curves based on historical performance once sufficient data had been collected.

  4. Statistical methods for pavement performance curve building, historical analysis, data sampling and storage: Appendix D. Final report

    SciTech Connect

    1998-08-01

    The technical memorandum is intended to discuss the detailed procedure required for carrying out the statistical analyses of historical pavement condition data for building pavement performance curves. This chapter assumes the availability of the historical data in a spreadsheet format (Microsoft{trademark} Excel) that has been retrieved from the master (pavement management system) database.

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

    SciTech Connect

    Loh, S.W.; Olek, J.

    1999-05-01

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

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

    NASA Astrophysics Data System (ADS)

    LaCroix, Andrew Thomas

    In the pavement industry in the United States of America, there is an increasing desire to improve the pavement construction quality and life for new and rehabilitated pavements. In order to improve the quality of the pavements, the Federal Highway Administration (FHWA) has pursued a performance-related specification (PRS) for over 20 years. The goal of PRS is to provide material and construction (M/C) properties that correlate well with pavement performance. In order to improve upon the PRS projects developed in WesTrack (NCHRP 9-20) and the MEPDG-based PRS (NCHRP 9-22), a set of PRS tests and models are proposed to provide a critical link between pavement performance and M/C properties. The PRS testing is done using the asphalt mixture performance tester (AMPT). The proposed PRS focuses on rutting and fatigue cracking of asphalt mixtures. The mixtures are characterized for their stiffness, fatigue behavior, and rutting resistance using a dynamic modulus (|E*|) test, a fatigue test, and a triaxial stress sweep (TSS) test, respectively. Information from the fatigue test characterizes the simplified viscoelastic continuum damage (S-VECD) model. Once the stiffness is reduced to a certain level, the material develops macro-cracks and fails. The TSS test is used to characterize a viscoplastic (VP) model. The VP model allows the prediction of the rut depth beneath the center of the wheel. The VECD and VP models are used within a layered viscoelastic (LVE) pavement model to predict fatigue and rutting performance of pavements. The PRS is evaluated by comparing the predictions to the field performance at the NCAT pavement test track in Opelika, Alabama. The test track sections evaluated are part of the 2009 test cycle group experiment, which focused on WMA, high RAP (50%), and a combination of both. The fatigue evaluation shows that all sections would last at least 18 years at the same traffic rate. The sections do not show any cracking, suggesting the sections are well-built and a long life is possible. The rutting in the test track is also predicted. All the predicted rut depths are 2-4 mm higher than measured in the field, but the overall ranking of different pavement sections matches the ranking in the field quite well. Conclusions and recommendations for future research are drawn from the observations made from experimental results as well as performance prediction of NCAT pavement sections.

  7. Performance of concrete pavements containing recycled concrete aggregate. Interim report, October 1993-October 1996

    SciTech Connect

    Wade, M.J.; Cuttell, G.D.; Vandenbossche, J.M.; Yu, H.T.; Smith, K.D.

    1997-03-01

    This interim report documents the field performance of nine concrete pavement projects that incorporate recycled concrete aggregate (RCA) in the construction of the pavement. Multiple sections were evaluated on many of the nine projects, due to perceived differences in performance levels or variations in pavement design (such as the use of virgin aggregate or the inclusion of dowel bars). All told, a total of 17 sections (of which 12 contain RCA) were subjected to an extensive field testing program, consisting of pavement condition surveys, drainage surveys, falling weight deflectometer (FWD) testing, coring, and serviceability assessments. A minimum of eight cores were retrieved from each section for laboratory evaluation of compressive strength, split tensile strength, dynamic elastic modulus, static elastic modulus, and thermal coefficient of expansion, as well as for volumetric surface testing and petrographic analyses.

  8. PERFORMANCE-BASED CONTRACTING IN CONSTRUCTION PHASE AND MAINTENANCE PHASE OF PAVEMENT

    NASA Astrophysics Data System (ADS)

    Yoshida, Takeshi

    Performance-based contracting for pavement in Japan started as performance warranties in construction phase, in 1999. Recently, road agencies have recognized the applicability of this type of contracting in outsourcing of maintenance activities. The objectives of this study are to clarify the issues of performance specifying in construction phase and maintenance phase of pavement, and to propose measures to be taken. This paper, with the recognition that the life of each pavement depends on performance standards for various attributes, reviews domestic and foreign examples of performance-based contracting. A performance standard based on the average of current practices can enhance product quality and service life with a warranty contract. Repair thresholds and response time for each deficiency should be considered as performance standards in maintenance phase.

  9. The effect of cracking on the deflection basin of flexible pavements

    NASA Astrophysics Data System (ADS)

    Omar, Hadi Mohamed

    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.

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

    EPA Science Inventory

    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...

  11. Evaluation of various surface-sealing techniques for the preventative maintenance of flexible pavements. Research report(Final)

    SciTech Connect

    Musselman, J.A.; Leitner, E.B.; Murphy, K.H.; Page, G.C.

    1989-02-01

    The selection of an appropriate surface-seal technique for the preventative maintenance of flexible pavements has been a major concern among the various highway agencies for a number of years. In an effort to better equip the engineer in making decisions concerning the selection of the most cost-effective method of pavement maintenance, seven of the different surface-sealing techniques currently available in Florida were constructed in the fall of 1984 for evaluation. The only major problems encountered at the time of construction was the loss of cover material in the sand seal, mineral seal, and surface-treatment sections and raveling in the slurry seal section. These problems are believed to have been caused by traffic on the roadway before adequate curing had occurred. The test sections were evaluated immediately after construction and at 6 months, 1 year, 2 years, and 3 years, with the evaluation consisting of rut-depth measurements, crack survey, dynamic deflection measurements, rideability, and friction testing. At the conclusion of 3 years, the cost-effectiveness of each section was determined.

  12. Hydraulic and treatment performance of pervious pavements under variable drying and wetting regimes.

    PubMed

    Yong, C F; Deletic, A; Fletcher, T D; Grace, M R

    2011-01-01

    Pervious pavements are an effective stormwater treatment technology. However, their performance under variable drying and wetting conditions have yet to be tested, particularly under a continuous time scale. This paper reports on the clogging behaviour and pollutant removal efficiency of three pervious pavement types over 26 accelerated years. These pavements were monolithic porous asphalt (PA), Permapave (PP) and modular Hydrapave (HP). Over a cycle of 13 days, the period of which was equivalent to the average annual Brisbane, Australia rainfall (1,200 mm), the pavements were randomly dosed with four different flows. Drying events of 3 h duration were simulated during each flow. Inflow and outflow samples were collected and analysed for Total Suspended Solids (TSS), Total Phosphorus (TP) and Total Nitrogen (TN). To evaluate the rate of clogging, a 1 in 5 year Brisbane storm event was simulated in the 6th, 8th, 12th, 16th, 20th and 24th week. Under normal dosing conditions, none of the pavements showed signs of clogging even after 15 years. However, under storm conditions, both PA and HP started to clog after 12 years, while PP showed no signs of clogging after 26 years. The drying and various flow events showed no effects in TSS removal, with all systems achieving a removal of approximately 100%. The average TP removal was 20% for all flows except for low flow, which had a significant amount of leaching over time. Leaching from TN was also observed during all flows except high flow. The TSS, TP and TN results observed during storm events were similar to that of high flow. PMID:22335113

  13. High performance flexible heat pipes

    NASA Technical Reports Server (NTRS)

    Shaubach, R. M.; Gernert, N. J.

    1985-01-01

    A Phase I SBIR NASA program for developing and demonstrating high-performance flexible heat pipes for use in the thermal management of spacecraft is examined. The program combines several technologies such as flexible screen arteries and high-performance circumferential distribution wicks within an envelope which is flexible in the adiabatic heat transport zone. The first six months of work during which the Phase I contract goal were met, are described. Consideration is given to the heat-pipe performance requirements. A preliminary evaluation shows that the power requirement for Phase II of the program is 30.5 kilowatt meters at an operating temperature from 0 to 100 C.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  15. General outlook of pavement and vehicle dynamics

    SciTech Connect

    Mamlouk, M.S.

    1997-11-01

    The interaction between vehicle and pavement is complex since pavement roughness excites the dynamic forces generated by vehicles, while these dynamic forces simultaneously increase the pavement roughness. The objective of this paper is to provide an overview of the results of recent research related to pavement and vehicle dynamics and their interaction and to evaluate their potential use in the design and management of pavements. Pavement dynamic models are capable of determining stresses, strains, and deflections in various directions when harmonic, pulse, or transient loads are applied. Vehicle dynamic models simulate the effect of pavement roughness on the inertia of various vehicle components. These models can predict the dynamic forces produced by different axles and wheels of traveling vehicles at different locations along the pavement. Pavement response computed using dynamic models matches field measurements closer than those computed using static models. The concept of vehicle-pavement interaction can be applied to weigh-in-motion, pavement design and performance, and vehicle regulations.

  16. Relationships between laboratory measured HMA material and mixture properties and pavement performance at WesTrack

    NASA Astrophysics Data System (ADS)

    Hand, Adam J. T.

    For years researchers and practitioners alike in the pavements and materials industry have attempted to establish relationships between laboratory measured material and mixture properties and actual pavement performance. The ultimate goal of any highway agency is to have performance related specifications, which require such relationships. This sounds simple enough, but in reality such a task is not so simple due to the extremely complex behavior of hot mix asphalt. Due to the fact that it takes many years to evaluate new materials and methodologies, the use of accelerated loading facilities such as WesTrack for evaluation purposes becomes very advantageous. The research presented here produces multiple permanent deformation performance relationships for the WesTrack project, some of which may be extended to other environments. An attempt to develop similar fatigue performance relationships was unsuccessful due partially to the lack of fatigue distress at WesTrack to date. Additionally, mix design and some quality control data summaries are presented for the project along with an investigation into a potential cause of the premature rutting of coarse Superpave mixes. The investigation resulted in the development of precision statements for the ASTM D5821-95 coarse aggregate angularity test method and a better understanding of the sensitivity of coarse Superpave mixtures.

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

    PubMed

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

    2014-01-01

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

  18. Long-term stormwater quantity and quality performance of permeable pavement systems.

    PubMed

    Brattebo, Benjamin O; Booth, Derek B

    2003-11-01

    This study examined the long-term effectiveness of permeable pavement as an alternative to traditional impervious asphalt pavement in a parking area. Four commercially available permeable pavement systems were evaluated after 6 years of daily parking usage for structural durability, ability to infiltrate precipitation, and impacts on infiltrate water quality. All four permeable pavement systems showed no major signs of wear. Virtually all rainwater infiltrated through the permeable pavements, with almost no surface runoff. The infiltrated water had significantly lower levels of copper and zinc than the direct surface runoff from the asphalt area. Motor oil was detected in 89% of samples from the asphalt runoff but not in any water sample infiltrated through the permeable pavement. Neither lead nor diesel fuel were detected in any sample. Infiltrate measured 5 years earlier displayed significantly higher concentrations of zinc and significantly lower concentrations of copper and lead. PMID:14511707

  19. Performance of pervious pavement parking bays storing rainwater in the north of Spain.

    PubMed

    Gomez-Ullate, E; Bayon, J R; Coupe, S; Castro-Fresno, D

    2010-01-01

    Pervious pavements are drainage techniques that improve urban water management in a sustainable manner. An experimental pervious pavement parking area has been constructed in the north of Spain (Santander), with the aim of harvesting good quality rainwater. Forty-five pervious pavement structures have been designed and constructed to measure stored water quantity and quality simultaneously. Ten of these structures are specifically constructed with different geotextile layers for improving water storage within the pavements. Following the confirmation in previous laboratory experiments that the geotextile influenced on water storage, two different geosynthetics (Inbitex and a One Way evaporation control membrane) and control pervious pavements with no geotextile layers were tested in the field. Weather conditions were monitored in order to find correlations with the water storage within the pervious pavement models tested. During one year of monitoring the three different pervious pavement types tested remained at their maximum storage capacity. The heavy rain events which occurred during the experimental period caused evaporation rates within the pervious pavements to be not significant, but allowed the researchers to observe certain trends in the water storage. Temperature was the most closely correlated weather factor with the level of the water stored within the pervious pavements tested. PMID:20706008

  20. Pavement performance monitoring using Dynamic Cone Penetrometer and Geogauge during construction

    NASA Astrophysics Data System (ADS)

    Ahsan, Ahmed Nawal

    Proper design life of road network system requires adequate quality control measures during the construction process to ensure proper material quality and sufficient strength in between the materials. Laboratory tests are often time consuming and sometimes, are not practical while the construction work is going on, in-situ techniques can efficiently evaluate the material properties through simple and less time consuming procedures. Dynamic Cone Penetrometer and Geogauge can play a vital role as an in-situ testing equipment because both have the potential to measure the change in material properties through field tests being performed in the field. Both in-situ techniques was not extensively used in North Texas area. Frequent use of these two equipment during the construction process can expedite the whole construction process because both are hand-held devices and can be conducted within a short amount of time, often in minutes. For this study, Dynamic Cone Penetrometer and Geogauge was used to assess the material properties from the tests performed on five construction sites of Horseshoe Project around Dallas, TX. Several points across the width of the pavement have been considered to perform these in-situ tests along with Nuclear Density Gauge test in two of these sites. A thorough analysis has been conducted for the material properties to be determined. Dynamic Cone Penetrometer and Geogauge both were consistent to measure the change in in-place material characteristics of the pavement materials. The design thickness of cement treated base layer where the tests were being performed was 6". DCP was efficient enough to detect the layer thickness up to a proximity of 0.5 inch and was also able to distinguish layer anomalies between the pavement layers. Cement stabilized base layer provided with a DCPI value which ranges from 0.5 mm/blow to 8 mm/blow whereas, DCPI values were observed to remain within a range of 2 mm/blow to 22 mm/ blow. For the top 6" cement treated base layer, unconfined compressive strength was found vary between 210 psi to 1023.5 psi. The highest resilient moduli value was found at the middle of the cement stabilized base layer where it varied from 40,500 psi -- 623,285 psi. Young's moduli values for cement stabilized base layer measured with Geogauge also followed the same trend of resilient moduli obtained from the measurements taken with Dynamic Cone Penetrometer.

  1. Material characterization for studing flexible pavement behavior in fatigue and permanent deformation

    NASA Astrophysics Data System (ADS)

    Elmitiny, M. R. N.

    1980-03-01

    Mixtures' performances in fatigue and rutting were investigated. Different aggregates and gradations were studied in these mixtures. The aggregates and gradations chosen were investigated using Marshall design criteria. These aggregates were first evaluated for basic material characteristics such as specific gravity and water absorption for both fine and course fractions. Also, the Marshall stability, density and air voids contents were known at different asphalt contents. To investigate rutting susceptibility for different mixes under study, a dynamic uniaxial loading in which the dynamic stress intensities were varied within a certain range to simulate field conditions was conducted. All mixtures studied in fatigue showed that the crack propagation rate versus stress intensity factors can be represented with a polynomial of a second degree. Statistical relations were developed to correlate the rutting and fatigue parameters under investigation in this study with other mix variables. The rutting parameters were found mostly to be influenced by asphalt contents and aggregate type. The fatigue parameters were found to be affected by asphalt contents, gradations and modulus of elasticity.

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

    EPA Science Inventory

    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...

  3. Development and performance research of FBG strain sensor for monitoring on asphalt concrete pavement

    NASA Astrophysics Data System (ADS)

    Hu, Qingli; Wang, Chuan; Ou, Jinping

    2010-04-01

    Stiffness of asphalt concrete is very low, so ordinary FRP or steel packaged sensors are not suitable for measuring its strain accurately. In view of the problem, one innovative kind of optical fiber Bragg grating sensor packaged with polypropylene, a thermoplastic resin, was proposed in this article. Firstly, a conveniently assembled and dissembled steel die was designed and fabricated. Then, after characteristics study of polypropylene during heating and cooling repeatedly, the reliable grouting technique was formed. After this, real-time monitor of the entire sensor packaging process including die apartness was performed, and then, the sensor mechanics performance, the microscopic structure and other properties were studied thoroughly. Results of SEM indicate that interface of optical fiber and polypropylene is considerable tight. Measured strain during sensor making is reasonable. The FBG sensor was also embedded into a concrete column to measure its strain during continuously 7 day-long early-age solidification and compressive strain. Additionally, the FBG was also used to measure strain of asphalt concrete beam. Linearity and repeatability of the sensors are quit well and measured strains are quite believable. So, we can say that due to deformation compatibility between packaged material and FBG, FBG sensor and be measured material, especially low modulus of packaging materials, the strain of asphalt pavement can be monitored reliably by the sensor.

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

    EPA Science Inventory

    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 EPAs Urb...

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

    EPA Science Inventory

    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...

  6. Stormwater infiltration and surface runoff pollution reduction performance of permeable pavement layers.

    PubMed

    Niu, Zhi-Guang; Lv, Zhi-Wei; Zhang, Ying; Cui, Zhen-Zhen

    2016-02-01

    In this paper, the laboratory-scale permeable pavement layers, including a surface permeable brick layer, coarse sand bedding layers (thicknesses = 2, 3.5, and 5 cm), and single-graded gravel sub-base layers (thicknesses = 15, 20, 25, and 30 cm), were built to evaluate stormwater infiltration and surface runoff pollution reduction performance. And, the infiltration rate (I) and concentrations of suspended solids (SS), total phosphorus (TP), chemical oxygen demand (COD), ammonia nitrogen, and total nitrogen (TN) were measured under the simulated rainfall intensity of 72.4 mm/h over duration of 60 min. The results indicate that the thickness factor primarily influences the infiltration rate and pollutant removal rate. The highest steady infiltration rate was for surface brick layer 51.0 mm/h, for 5-cm sand bedding layer 32.3 mm/h, and for 30-cm gravel sub-base layer 42.3 mm/h, respectively. The SS average removal rate was relative higher (79.8 ∼ 98.6 %) for all layers due to the interception and filtration. The average removal rates of TP and COD were for surface layer 71.2 and 24.1 %, for 5-cm bedding layer 54.8 and 9.0 %, and for 20-cm sub-base layer 72.2 and 26.1 %. Ammonia nitrogen and TN cannot steadily be removed by layers according to the experiment results. The optimal thickness of bedding sands was 5 cm, and that of sub-base gravels was 20 ∼ 30 cm. PMID:26429141

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

    NASA Astrophysics Data System (ADS)

    Faeth, Benjamin Michael

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

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

    PubMed

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

    2014-01-01

    In recent years, the application of titanium dioxide (TiO₂) 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 TiO₂ 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 TiO₂ 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

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

    PubMed

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

    2014-01-01

    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

  10. Compaction of asphalt pavement. Final report

    SciTech Connect

    Hughes, C.S.

    1989-10-01

    This synthesis will be of interest to construction and materials engineers, paving contractors, equipment manufacturers, and others who are involved in assessing the performance of asphalt pavements. Information is presented on various issues related to compaction of asphalt pavements. Compaction is one of the most important factors affecting the performance of asphalt pavements. The report of the Transportation Research Board describes the theory, methods, equipment, and specifications related to the compaction of asphalt pavements. A brief history of, the importance of, and factors affecting compaction are also discussed. Construction influences, density measurements, and trends are also considered.

  11. In-depth study of cold in-place recycled-pavement performance. Volume 1. Final report. Rept. for Dec 88-Oct 90

    SciTech Connect

    Scholz, T.V.; Hicks, R.G.; Rogge, D.F.

    1990-12-01

    Oregon has developed a mix design procedure for cold in-place recycled (CIR) asphalt concrete pavements. The procedure involves estimation of an initial emulsion content based on gradation of recycled asphalt pavement (RAP), asphalt content of RAP, and penetration and viscosity of recovered asphalt. When an estimated emulsion content is determined, Marshall-sized specimens are prepared for a range of emulsion contents with the range centered on the estimated emulsion content. Hveem and Marshall stability, resilient modulus, and index of retained modulus (IRM) tests are performed on the specimens and a design emulsion content is selected based upon these results. Because of variations in RAP properties, continual need for field adjustments, and the difficulty of interpreting mix property test results, only the estimation part of the procedure is currently implemented. The paper describes the mix design procedure and presents lab results demonstrating the difficulty of choosing emulsion content based on Hveem and Marshall stability, resilient modulus and IRM. Data comparing design emulsion content with actual emulsion contents used in the field are presented. Selection of water content is discussed. Test results of mix properties monitored over time are presented, demonstrating the curing of the emulsion. Performance data for CIR pavements constructed from 1984 through 1988 are presented as well as initial results of an attempt to use lime during recycling to correct a stripped pavement. A construction and inspection manual is presented as a separate document.

  12. Effects of Using Silica Fume and Polycarboxylate-Type Superplasticizer on Physical Properties of Cementitious Grout Mixtures for Semiflexible Pavement Surfacing

    PubMed Central

    Karim, Mohamed Rehan; Mahmud, Hilmi; Mashaan, Nuha S.; Katman, Herdayati; Husain, Nadiah Md

    2014-01-01

    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

  13. In-situ infiltration performance of different permeable pavements in a employee used parking lot--A four-year study.

    PubMed

    Kumar, Kuldip; Kozak, Joseph; Hundal, Lakhwinder; Cox, Albert; Zhang, Heng; Granato, Thomas

    2016-02-01

    Permeable pavements are being adopted as a green solution in many parts of the world to manage urban stormwater quantity and quality. This paper reports on the measured in-situ infiltration performance over a four-year period since construction and use of three permeable parking sections (permeable pavers, permeable concrete and permeable asphalt) of an employee car parking lot. There was only a marginal decline in infiltration rates of all three pavements after one year of use. However, between years two to four, the infiltration rates declined significantly due to clogging of pores either by dry deposition of particles and/or shear stress of vehicles driving and degrading the permeable surfaces; during the last two years, a greater decline was also observed in driving areas of the parking lots compared to parking slots, where minimal wear and tear are expected. Maintenance strategies were employed to reclaim some of the lost infiltration rate of the permeable pavements to limited success. Despite this decline, the infiltration rates were still four to five times higher than average rainstorm intensity in the region. Thus, these permeable pavement parking lots may have significant ecological importance due to their ability to infiltrate rainwater quickly, reduce the runoff in the catchment area, and also dampen runoff peak flows that could otherwise enter the collection system for treatment in a combined sewer area. PMID:26606196

  14. High performance flexible electronics for biomedical devices.

    PubMed

    Salvatore, Giovanni A; Munzenrieder, Niko; Zysset, Christoph; Kinkeldei, Thomas; Petti, Luisa; Troster, Gerhard

    2014-01-01

    Plastic electronics is soft, deformable and lightweight and it is suitable for the realization of devices which can form an intimate interface with the body, be implanted or integrated into textile for wearable and biomedical applications. Here, we present flexible electronics based on amorphous oxide semiconductors (a-IGZO) whose performance can achieve MHz frequency even when bent around hair. We developed an assembly technique to integrate complex electronic functionalities into textile while preserving the softness of the garment. All this and further developments can open up new opportunities in health monitoring, biotechnology and telemedicine. PMID:25570912

  15. Flexibility and Performance of Parallel File Systems

    NASA Technical Reports Server (NTRS)

    Kotz, David; Nieuwejaar, Nils

    1996-01-01

    As we gain experience with parallel file systems, it becomes increasingly clear that a single solution does not suit all applications. For example, it appears to be impossible to find a single appropriate interface, caching policy, file structure, or disk-management strategy. Furthermore, the proliferation of file-system interfaces and abstractions make applications difficult to port. We propose that the traditional functionality of parallel file systems be separated into two components: a fixed core that is standard on all platforms, encapsulating only primitive abstractions and interfaces, and a set of high-level libraries to provide a variety of abstractions and application-programmer interfaces (API's). We present our current and next-generation file systems as examples of this structure. Their features, such as a three-dimensional file structure, strided read and write interfaces, and I/O-node programs, are specifically designed with the flexibility and performance necessary to support a wide range of applications.

  16. A Study on the Estimation of the Performance of Sediment Pavement and the Required Function of the Farm Road in a Paddy Area

    NASA Astrophysics Data System (ADS)

    Ogata, Hidehiko; Noda, Tomoyuki; Sakamoto, Yasufumi; Shinotsuka, Masanori; Kamada, Osamu; Nakamura, Kazuaki

    The pavement rate of the farm road which becomes important in activities of agricultural production, circulation of agricultural products and rural life is low. There are many farm roads to which the function of traveling performance, traveling comfort and prevention of the damage of agricultural products in transportation is not secured. Maintenance including improvement in the pavement rate of a farm road must be economically carried out based on the service environment, the circumference environment and the required function according to the kind of farm road. In this research, the problem of the farm road in a paddy area was extracted from the questionnaire to a land improvement district as an administrator, and the conditions which should be taken into consideration in maintenance of a farm road were clarified. The problem of a farm road is deformation of a road surface and a request is a period which does not need to repair. Moreover, the present performance of ground property and road surface of sediment pavement on-farm road was evaluated. Positive correlation is between the standard deviation of modulus of elasticity of the soil and surface roughness, negative correlation is between the modulus of elasticity of the soil in the rut and rutting depth.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    EPA Science Inventory

    To meet the need for long-term, 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...

  19. Rubber modified and performance based asphalt binder pavements: I-5 Nisqually River to Gravelly Lake. Post construction report

    SciTech Connect

    Pierce, L.M.

    1996-01-01

    The report describes the construction of asphalt pavements made with three types of asphalt binders. The three types of binders were PBA-6, PBA-6GR (ground rubber), and AR4000W. The two modified binders, PBA-6 and PBA-6GR, are being evaluated to determine their resistance to rutting as compared to the conventional binder, AR4000W.

  20. Quantitative analysis of microtubule orientation in interdigitated leaf pavement cells.

    PubMed

    Akita, Kae; Higaki, Takumi; Kutsuna, Natsumaro; Hasezawa, Seiichiro

    2015-01-01

    Leaf pavement cells are shaped like a jigsaw puzzle in most dicotyledon species. Molecular genetic studies have identified several genes required for pavement cells morphogenesis and proposed that microtubules play crucial roles in the interdigitation of pavement cells. In this study, we performed quantitative analysis of cortical microtubule orientation in leaf pavement cells in Arabidopsis thaliana. We captured confocal images of cortical microtubules in cotyledon leaf epidermis expressing GFP-tubulinβ and quantitatively evaluated the microtubule orientations relative to the pavement cell growth axis using original image processing techniques. Our results showed that microtubules kept parallel orientations to the growth axis during pavement cell growth. In addition, we showed that immersion treatment of seed cotyledons in solutions containing tubulin polymerization and depolymerization inhibitors decreased pavement cell complexity. Treatment with oryzalin and colchicine inhibited the symmetric division of guard mother cells. PMID:26039484

  1. Quantitative analysis of microtubule orientation in interdigitated leaf pavement cells

    PubMed Central

    Akita, Kae; Higaki, Takumi; Kutsuna, Natsumaro; Hasezawa, Seiichiro

    2015-01-01

    Leaf pavement cells are shaped like a jigsaw puzzle in most dicotyledon species. Molecular genetic studies have identified several genes required for pavement cells morphogenesis and proposed that microtubules play crucial roles in the interdigitation of pavement cells. In this study, we performed quantitative analysis of cortical microtubule orientation in leaf pavement cells in Arabidopsis thaliana. We captured confocal images of cortical microtubules in cotyledon leaf epidermis expressing GFP-tubulinβ and quantitatively evaluated the microtubule orientations relative to the pavement cell growth axis using original image processing techniques. Our results showed that microtubules kept parallel orientations to the growth axis during pavement cell growth. In addition, we showed that immersion treatment of seed cotyledons in solutions containing tubulin polymerization and depolymerization inhibitors decreased pavement cell complexity. Treatment with oryzalin and colchicine inhibited the symmetric division of guard mother cells. PMID:26039484

  2. High-Performance Flexible Waveguiding Photovoltaics

    PubMed Central

    Chou, Chun-Hsien; Chuang, Jui-Kang; Chen, Fang-Chung

    2013-01-01

    The use of flat-plane solar concentrators is an effective approach toward collecting sunlight economically and without sun trackers. The optical concentrators are, however, usually made of rigid glass or plastics having limited flexibility, potentially restricting their applicability. In this communication, we describe flexible waveguiding photovoltaics (FWPVs) that exhibit high optical efficiencies and great mechanical flexibility. We constructed these FWPVs by integrating poly-Si solar cells, a soft polydimethylsiloxane (PDMS) waveguide, and a TiO2-doped backside reflector. Optical microstructures that increase the light harvesting ability of the FWPVs can be fabricated readily, through soft lithography, on the top surface of the PDMS waveguide. Our optimized structure displayed an optical efficiency of greater than 42% and a certified power conversion efficiency (PCE) of 5.57%, with a projected PCE as high as approximately 18%. This approach might open new avenues for the harvesting of solar energy at low cost with efficient, mechanically flexible photovoltaics. PMID:23873225

  3. STATUS OF POROUS PAVEMENT RESEARCH

    EPA Science Inventory

    This paper discusses the U.S. Environmental Protection Agency's porous pavement research program along with the economics, advantages, potential applications, and status and future research needs of porous pavements. Porous pavements are an available stormwater management techniq...

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

    SciTech Connect

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

    2011-02-05

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

  5. Asphalt in Pavement Maintenance.

    ERIC Educational Resources Information Center

    Asphalt Inst., College Park, MD.

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

  6. Pavement management practices. Final report

    SciTech Connect

    Peterson, D.E.

    1987-11-01

    This synthesis will be of interest to pavement designers, maintenance engineers, and others responsible for the management of highway pavements. Information is presented on pavement management systems - the established, documented procedures used to treat all activities involved in providing and sustaining pavements in an acceptable condition. As highway agencies focus more attention on maintenance and rehabilitation of highway networks, the use of some form of a pavement management system becomes increasingly important. This report of the Transportation Research Board describes the features, applicability, and used of a pavement management system and recommends five general steps for implementing a new pavement management system or improving an existing system.

  7. Organic optoelectronic devices-flexibility versus performance

    NASA Astrophysics Data System (ADS)

    Chakaroun, M.; El Amrani, A.; Lucas, B.; Ratier, B.; Aldissi, M.

    2010-09-01

    In this paper, we discuss the effect of flexible substrates on the characteristics of two organic optoelectronic devices, namely P3HT:PCBM-based photovoltaic bulk heterojunctions and pentacene-based phototransistors. In addition, we have developed anode materials deposited by ion beam sputtering, a technique which satisfies the low temperature deposition requirements associated with the use of plastic substrates. The anode materials consisted of indium tin oxide (ITO) and ITO/metal/ITO tri-layers. The use of tri-layer anodes in P3HT:PCBM-based solar cells resulted in an increase in the fill factor and the power conversion efficiency reached a value of 2% with an ITO(70 nm)/Ag(14 nm)/ITO(70 nm) anode deposited on a polyphthalate carbonate substrate. In the case of phototransistors, a photosensitivity of 1.6 × 104 under illumination at 365 nm (with a power intensity of 7 mW/cm2) was obtained in the off-state of the transistor. We have fine-tuned the anode structure and deposition/annealing conditions towards flexible organic devices and optimal device characteristics.

  8. Influence of hinge point on flexible flap aerodynamic performance

    NASA Astrophysics Data System (ADS)

    Y Zhao, H.; Ye, Z.; Wu, P.; Li, C.

    2013-12-01

    Large scale wind turbines lead to increasing blade lengths and weights, which presents new challenges for blade design. This paper selects NREL S809 airfoil, uses the parameterized technology to realize the flexible trailing edge deformation, researches the static aerodynamic characteristics of wind turbine blade airfoil with flexible deformation, and the dynamic aerodynamic characteristics in the process of continuous deformation, analyses the influence of hinge point position on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With hinge point moving forward, total aerodynamic performance of flexible flap improves. Positive swing angle can push the transition point backward, thus postpones the occurrence of the transition phenomenon.

  9. Flexible nanoscale high-performance FinFETs.

    PubMed

    Torres Sevilla, Galo A; Ghoneim, Mohamed T; Fahad, Hossain; Rojas, Jhonathan P; Hussain, Aftab M; Hussain, Muhammad Mustafa

    2014-10-28

    With the emergence of the Internet of Things (IoT), flexible high-performance nanoscale electronics are more desired. At the moment, FinFET is the most advanced transistor architecture used in the state-of-the-art microprocessors. Therefore, we show a soft-etch based substrate thinning process to transform silicon-on-insulator (SOI) based nanoscale FinFET into flexible FinFET and then conduct comprehensive electrical characterization under various bending conditions to understand its electrical performance. Our study shows that back-etch based substrate thinning process is gentler than traditional abrasive back-grinding process; it can attain ultraflexibility and the electrical characteristics of the flexible nanoscale FinFET show no performance degradation compared to its rigid bulk counterpart indicating its readiness to be used for flexible high-performance electronics. PMID:25185112

  10. Advanced self-healing asphalt composites in the pavement performance field: mechanisms at the nano level and new repairing methodologies.

    PubMed

    Agzenai, Yahya; Pozuelo, Javier; Sanz, Javier; Perez, Ignacio; Baselga, Juan

    2015-01-01

    In an effort to give a global view of this field of research, in this mini-review we highlight the most recent publications and patents focusing on modified asphalt pavements that contain certain reinforcing nanoparticles which impart desirable thermal, electrical and mechanical properties. In response to the increasing cost of asphalt binder and road maintenance, there is a need to look for alternative technologies and new asphalt composites, able to self-repair, for preserving and renewing the existing pavements. First, we will focus on the self-healing property of asphalt, the evidences that support that healing takes place immediately after the contact between the faces of a crack, and how the amount of healing can be measured in both the laboratory and the field. Next we review the hypothetical mechanisms of healing to understand the material behaviour and establish models to quantify the damage-healing process. Thereafter, we outline different technologies, nanotechnologies and methodologies used for self-healing paying particular attention to embedded micro-capsules, new nano-materials like carbon nanotubes and nano-fibres, ionomers, and microwave and induction heating processes. PMID:25479339

  11. An advanced algorithm for highway pavement fissure detection

    NASA Astrophysics Data System (ADS)

    Chen, Bei; Cao, Wenlun; He, Yuyao

    2012-04-01

    This paper presents image detection method of pavement crack based on fractal dimension feature and designs self-adapting algorithm of fractal dimension interval of pavement region. Through image pretreatment, calculation of fractal dimension, self-adapting calculation of dimension interval, we obtain the location image of damage pavement. The experimental results of transverse crack, longitudinal crack, net-shaped crack, pit slot are contrast with that of Sobel operator. The results show that they have the similar capability on the representation of crack, but the proposed method is more flexible on the aspect of representation of crack size and calculation of damage ratio.

  12. Pervious Pavement System Evaluation

    EPA Science Inventory

    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...

  13. Flexibility.

    ERIC Educational Resources Information Center

    Humphrey, L. Dennis

    1981-01-01

    Flexibility is an important aspect of all sports and recreational activities. Flexibility can be developed and maintained by stretching exercises. Exercises designed to develop flexibility in ankle joints, knees, hips, and the lower back are presented. (JN)

  14. Modeling the Hydrologic Processes of a Permeable Pavement System

    EPA Science Inventory

    A permeable pavement system can capture stormwater to reduce runoff volume and flow rate, improve onsite groundwater recharge, and enhance pollutant controls within the site. A new unit process model for evaluating the hydrologic performance of a permeable pavement system has be...

  15. Flexibility of movement organization in piano performance.

    PubMed

    Furuya, Shinichi; Altenmüller, Eckart

    2013-01-01

    Piano performance involves a large repertoire of highly skilled movements. The acquisition of these exceptional skills despite innate neural and biomechanical constraints requires a sophisticated interaction between plasticity of the neural system and organization of a redundant number of degrees of freedom (DOF) in the motor system. Neuroplasticity subserving virtuosity of pianists has been documented in neuroimaging studies investigating effects of long-term piano training on structure and function of the cortical and subcortical regions. By contrast, recent behavioral studies have advanced the understanding of neuromuscular strategies and biomechanical principles behind the movement organization that enables skilled piano performance. Here we review the motor control and biomechanics literature, introducing the importance of describing motor behaviors not only for understanding mechanisms responsible for skillful motor actions in piano playing, but also for advancing diagnosis and rehabilitation of movement disorders caused by extensive piano practice. PMID:23882199

  16. Flexibility of movement organization in piano performance

    PubMed Central

    Furuya, Shinichi; Altenmüller, Eckart

    2013-01-01

    Piano performance involves a large repertoire of highly skilled movements. The acquisition of these exceptional skills despite innate neural and biomechanical constraints requires a sophisticated interaction between plasticity of the neural system and organization of a redundant number of degrees of freedom (DOF) in the motor system. Neuroplasticity subserving virtuosity of pianists has been documented in neuroimaging studies investigating effects of long-term piano training on structure and function of the cortical and subcortical regions. By contrast, recent behavioral studies have advanced the understanding of neuromuscular strategies and biomechanical principles behind the movement organization that enables skilled piano performance. Here we review the motor control and biomechanics literature, introducing the importance of describing motor behaviors not only for understanding mechanisms responsible for skillful motor actions in piano playing, but also for advancing diagnosis and rehabilitation of movement disorders caused by extensive piano practice. PMID:23882199

  17. Overview of the Arizona Quiet Pavement Program

    NASA Astrophysics Data System (ADS)

    Donavan, Paul; Scofield, Larry

    2005-09-01

    The Arizona Quiet Pavement Pilot Program (QP3) was initially implemented to reduce highway related traffic noise by overlaying most of the Phoenix metropolitan area Portland cement concrete pavement with a one inch thick asphalt rubber friction coarse. With FHWA support, this program represents the first time that pavement surface type has been allowed as a noise mitigation strategy on federally funded projects. As a condition of using pavement type as a noise mitigation strategy, ADOT developed a ten-year, $3.8 million research program to evaluate the noise reduction performance over time. Historically, pavement surface type was not considered a permanent solution. As a result, the research program was designed to specifically address this issue. Noise performance is being evaluated through three means: (1) conventional roadside testing within the roadway corridor (e.g., far field measurements within the right-of-way) (2) the use of near field measurements, both close proximity (CPX) and sound intensity (SI); and (3) far field measurements obtained beyond the noise barriers within the surrounding neighborhoods. This paper provides an overview of the program development, presents the research conducted to support the decision to overlay the urban freeway, and the status of current research.

  18. High-performance, flexible, deployable array development for space applications

    NASA Technical Reports Server (NTRS)

    Gehling, Russell N.; Armstrong, Joseph H.; Misra, Mohan S.

    1994-01-01

    Flexible, deployable arrays are an attractive alternative to conventional solar arrays for near-term and future space power applications, particularly due to their potential for high specific power and low storage volume. Combined with low-cost flexible thin-film photovoltaics, these arrays have the potential to become an enabling or an enhancing technology for many missions. In order to expedite the acceptance of thin-film photovoltaics for space applications, however, parallel development of flexible photovoltaics and the corresponding deployable structure is essential. Many innovative technologies must be incorporated in these arrays to ensure a significant performance increase over conventional technologies. For example, innovative mechanisms which employ shape memory alloys for storage latches, deployment mechanisms, and array positioning gimbals can be incorporated into flexible array design with significant improvement in the areas of cost, weight, and reliability. This paper discusses recent activities at Martin Marietta regarding the development of flexible, deployable solar array technology. Particular emphasis is placed on the novel use of shape memory alloys for lightweight deployment elements to improve the overall specific power of the array. Array performance projections with flexible thin-film copper-indium-diselenide (CIS) are presented, and government-sponsored solar array programs recently initiated at Martin Marietta through NASA and Air Force Phillips Laboratory are discussed.

  19. Effects of structure flexibility on horizontal axis wind turbine performances

    NASA Astrophysics Data System (ADS)

    Coiro, D. P.; Daniele, E.; Scherillo, F.

    2013-10-01

    This work illustrates the effects of flexibility of rotor blades and turbine tower on the performances of an horizontal axis wind turbine (HAWT) designed by our ADAG research group, by means of several example applied on a recent project for a active pitch controlled upwind 60 kW HAWT. The influence of structural flexibility for blade only, tower only and blade coupled with tower configuration is investigated using an aero-elastic computer-aided engineering (CAE) tool for horizontal axis wind turbines named FAST developed at National Renewable Energy Laboratory (NREL) of USA. For unsteady inflow conditions in front of the isolated HAWT the performances in rigid and flexible operation mode are computed and compared in order to illustrate the limitation included within a classical rigid body approach to wind turbine simulation.

  20. Performance analysis of flexible DSSC with binder addition

    NASA Astrophysics Data System (ADS)

    Muliani, Lia; Hidayat, Jojo; Anggraini, Putri Nur

    2016-04-01

    Flexible DSSC is one of modification of DSSC based on its substrate. Operating at low temperature, flexible DSSC requires a binder to improve particles interconnection. This research was done to compare the morphology and performance of flexible DSSC that was produced with binder-added and binder-free. TiO2 powder, butanol, and HCl were mixed for preparation of TiO2 paste. Small amount of titanium isopropoxide as binder was added into the mixture. TiO2 paste was deposited on ITO-PET plastic substrate with area of 1x1 cm2 by doctor blade method. Furthermore, SEM, XRD, and BET characterization were done to analyze morphology and surface area of the TiO2 photoelectrode microstructures. Dyed TiO2 photoelectrode and platinum counter electrode were assembled and injected by electrolyte. In the last process, flexible DSSCs were illuminated by sun simulator to do J-V measurement. As a result, flexible DSSC containing binder showed higher performance with photoconversion efficiency of 0.31%.

  1. Overall Thermal Performance of Flexible Piping Under Simulated Bending Conditions

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)

    2001-01-01

    Flexible, vacuum-insulated transfer lines for low-temperature applications have higher thermal losses than comparable rigid lines. Typical flexible piping construction uses corrugated tubes, inner and outer, with a multilayer insulation (MLI) system in the annular space. Experiments on vacuum insulation systems in a flexible geometry were conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. The effects of bending were simulated by causing the inner tube to be eccentric with the outer tube. The effects of spacers were simulated in a controlled way by inserting spacer tubes for the length of the cylindrical test articles. Two material systems, standard MLI and a layered composite insulation (LCI), were tested under the full range of vacuum levels using a liquid nitrogen boiloff calorimeter to determine the apparent thermal conductivity (k-value). The results indicate that the flexible piping under simulated bending conditions significantly degrades the thermal performance of the insulation system. These data are compared to standard MLI for both straight and flexible piping configurations. The definition of an overall k-value for actual field installations (k(sub oafi)) is described for use in design and analysis of cryogenic piping systems.

  2. Influence of inflow angle on flexible flap aerodynamic performance

    NASA Astrophysics Data System (ADS)

    Y Zhao, H.; Ye, Z.; Li, Z. M.; Li, C.

    2013-12-01

    Large scale wind turbines have larger blade lengths and weights, which creates new challenges for blade design. This paper selects NREL S809 airfoil, and uses the parameterized technology to realize the flexible trailing edge deformation, researches the dynamic aerodynamic characteristics in the process of continuous flexible deformation, analyses the influence of inflow angle on flexible flap aerodynamic performance, in order to further realize the flexible wind turbine blade design and provides some references for the active control scheme. The results show that compared with the original airfoil, proper trailing edge deformation can improve the lift coefficient, reduce the drag coefficient, and thereby more efficiently realize flow field active control. With inflow angle increases, dynamic lift-drag coefficient hysteresis loop shape deviation occurs, even turns into different shapes. Appropriate swing angle can improve the flap lift coefficient, but may cause early separation of flow. To improve the overall performance of wind turbine blades, different angular control should be used at different cross sections, in order to achieve the best performance.

  3. Pervious Pavement System Evaluation

    EPA Science Inventory

    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...

  4. Community orientation, strategic flexibility, and financial performance in hospitals.

    PubMed

    Ginn, Gregory O; Lee, Ruby P

    2006-01-01

    The objective of this study was to examine how community orientation and strategic flexibility affect accounting measures of financial performance in acute care hospitals. This cross-sectional study used organizational data from the American Hospital Association, environmental data from the Area Resource File, and financial data from the Healthcare Cost Report Information System. We tested our hypotheses on 1,779 hospitals using OLS regression models that controlled for organizational and environmental factors that might affect financial performance. The community orientation of a hospital had a negative impact on its short-term financial performance. However, the strategic flexibility of a hospital with regard to structure and resources was significantly and positively associated with hospital performance. Our findings are important to healthcare managers. Specifically, although a community orientation is thought to be essential for improving the health of populations, the healthcare market may lack clarity concerning the wants and needs of patients and payers to such a degree that this orientation does not result in improved short-term financial performance. In contrast, when a hospital maintains flexibility in its resource allocations and organizational structure, it can meet changing needs and uncertainties and thereby enhance financial performance. PMID:16605221

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

    PubMed Central

    Wang, Huaping; Liu, Wanqiu; He, Jianping; Xing, Xiaoying; Cao, Dandan; Gao, Xipeng; Hao, Xiaowei; Cheng, Hongwei; Zhou, Zhi

    2014-01-01

    Pavements always play a predominant role in transportation. Health monitoring of pavements is becoming more and more significant, as frequently suffering from cracks, rutting, and slippage renders them prematurely out of service. Effective and reliable sensing elements are thus in high demand to make prognosis on the mechanical properties and occurrence of damage to pavements. Therefore, in this paper, various types of functionality enhancement of industrialized optical fiber sensors for pavement monitoring are developed, with the corresponding operational principles clarified in theory and the performance double checked by basic experiments. Furthermore, a self-healing optical fiber sensing network system is adopted to accomplish full-scale monitoring of pavements. The application of optical fiber sensors assembly and self-healing network system in pavement has been carried out to validate the feasibility. It has been proved that the research in this article provides a valuable method and meaningful guidance for the integrity monitoring of civil structures, especially pavements. PMID:24854060

  6. Functionality enhancement of industrialized optical fiber sensors and system developed for full-scale pavement monitoring.

    PubMed

    Wang, Huaping; Liu, Wanqiu; He, Jianping; Xing, Xiaoying; Cao, Dandan; Gao, Xipeng; Hao, Xiaowei; Cheng, Hongwei; Zhou, Zhi

    2014-01-01

    Pavements always play a predominant role in transportation. Health monitoring of pavements is becoming more and more significant, as frequently suffering from cracks, rutting, and slippage renders them prematurely out of service. Effective and reliable sensing elements are thus in high demand to make prognosis on the mechanical properties and occurrence of damage to pavements. Therefore, in this paper, various types of functionality enhancement of industrialized optical fiber sensors for pavement monitoring are developed, with the corresponding operational principles clarified in theory and the performance double checked by basic experiments. Furthermore, a self-healing optical fiber sensing network system is adopted to accomplish full-scale monitoring of pavements. The application of optical fiber sensors assembly and self-healing network system in pavement has been carried out to validate the feasibility. It has been proved that the research in this article provides a valuable method and meaningful guidance for the integrity monitoring of civil structures, especially pavements. PMID:24854060

  7. POROUS PAVEMENT: RESEARCH; DEVELOPMENT; AND DEMONSTRATION

    EPA Science Inventory

    This paper discusses the U.S. Environmental Protection Agency's porous pavement research program along with the economics, advantages, potential applications, and status and future research needs of porous pavements. Porous pavements are an available stormwater management techniq...

  8. Light Weight and Flexible High-Performance Diagnostic Platform.

    PubMed

    Karnaushenko, Daniil; Ibarlucea, Bergoi; Lee, Sanghun; Lin, Gungun; Baraban, Larysa; Pregl, Sebastian; Melzer, Michael; Makarov, Denys; Weber, Walter M; Mikolajick, Thomas; Schmidt, Oliver G; Cuniberti, Gianaurelio

    2015-07-15

    A flexible diagnostic platform is realized and its performance is demonstrated for early detection of avian influenza virus (AIV) subtype H1N1 DNA sequences. The key component of the platform is high-performance biosensors based on high output currents and low power dissipation Si nanowire field effect transistors (SiNW-FETs) fabricated on flexible 100 μm thick polyimide foils. The devices on a polymeric support are about ten times lighter compared to their rigid counterparts on Si wafers and can be prepared on large areas. While the latter potentially allows reducing the fabrication costs per device, the former makes them cost efficient for high-volume delivery to medical institutions in, e.g., developing countries. The flexible devices withstand bending down to a 7.5 mm radius and do not degrade in performance even after 1000 consecutive bending cycles. In addition to these remarkable mechanical properties, on the analytic side, the diagnostic platform allows fast detection of specific DNA sequences of AIV subtype H1N1 with a limit of detection of 40 × 10(-12) m within 30 min suggesting its suitability for early stage disease diagnosis. PMID:25946521

  9. Flexible body dynamic stability for high performance aircraft

    NASA Technical Reports Server (NTRS)

    Goforth, E. A.; Youssef, H. M.; Apelian, C. V.; Schroeder, S. C.

    1991-01-01

    Dynamic equations which include the effects of unsteady aerodynamic forces and a flexible body structure were developed for a free flying high performance fighter aircraft. The linear and angular deformations are assumed to be small in the body reference frame, allowing the equations to be linearized in the deformation variables. Equations for total body dynamics and flexible body dynamics are formulated using the hybrid coordinate method and integrated in a state space format. A detailed finite element model of a generic high performance fighter aircraft is used to generate the mass and stiffness matrices. Unsteady aerodynamics are represented by a rational function approximation of the doublet lattice matrices. The equations simplify for the case of constant angular rate of the body reference frame, allowing the effect of roll rate to be studied by computing the eigenvalues of the system. It is found that the rigid body modes of the aircraft are greatly affected by introducing a constant roll rate, while the effect on the flexible modes is minimal for this configuration.

  10. Experimental pavement using household waste slag

    SciTech Connect

    Kouda, Masahiro

    1996-12-31

    Municipal wastes used to be simply landfilled, but because of increasing difficulty in finding disposal sites, it became common practice to incinerate wastes and landfill the ash. In view of rapidly dwindling landfill sites, the author thought that the landfill site problem might be solved by finding a way to utilize slag made from incinerator ash. In this paper, a method for utilizing water-granulated slag as an asphalt pavement material is discussed. On the basis of laboratory test results, trial paving using base course materials consisting of crushed stone and 25 or 50% slag was carried out, paying attention primarily to bearing capacity. Marshall tests and fatigue resistance tests were conducted to determine the optimum content of water-granulated slag, and it was concluded that quality comparable to that of conventional asphalt concrete was attained at the slag content of 25% or less and that no problem would arise if the slag content was kept at 60% or less of the fine aggregate content. The mix proportions thus determined were also tested through experimental paving. A follow-up study to evaluate the durability of the experimental pavements confirmed that the experimental pavements were comparable in performance with conventional asphalt concrete pavements. This paper also reports on some problems encountered that need to be solved before utilizing water-granulated slag.

  11. Performance-based design and analysis of flexible composite propulsors

    NASA Astrophysics Data System (ADS)

    Motley, Michael R.; Young, Yin L.

    2011-11-01

    Advanced composite propellers, turbines, and jet engines have become increasingly popular in part because of their ability to provide improved performance over traditional metallic rotors through exploitation of the intrinsic bend-twist coupling characteristics of anisotropic composite materials. While these performance improvements can be significant from a conceptual perspective, the load-dependent deformation responses of adaptive blades make the design of these structures highly non-trivial. Hence, it is necessary to understand and predict the dependence of the deformations on the geometry, material constitution, and fluid-structure interaction responses across the entire range of expected loading conditions.The objective of this work is to develop a probabilistic performance-based design and analysis methodology for flexible composite propulsors. To demonstrate the method, it is applied for the design and analysis of two (rigid) metallic and (flexible) composite propellers for a twin-shafted naval combatant craft. The probabilistic operational space is developed by considering the variation of vessel thrust requirements as a function of the vessel speed and wave conditions along with the probabilistic speed profiles. The performance of the metallic and composite propellers are compared and discussed. The implications of load-dependent deformations of the flexible composite propeller on the operating conditions and the resulting performance with respect to propeller efficiency, power demand, and fluid cavitation are presented for both spatially uniform and varying flows. While the proposed framework is demonstrated for marine propellers, the methodology can be generally applied for any marine, aerospace, or wind energy structure that must operate in a wide range of loading conditions over its expected life.

  12. Asphalt pavement surfaces and asphalt mixtures. Transportation research record

    SciTech Connect

    1996-12-31

    The papers in this volume, which deal with asphalt pavement surfaces and asphalt mixtures, should be of interest to state and local construction, design, materials, and research engineers as well as contractors and material producers. The papers in Part 1 include discussions of pavement smoothness specifications and skidding characteristics. The first four papers in Part 2 were submitted in response to a call for papers for a session at the 75th Annual Meeting of the Transportation Research Board on low-temperature properties of hot-mix asphalt. The next eight are on the influence of volumetric and strength properties on the performance of hot-mix asphalt. In the following three papers, the topics covered are the complex modulus of asphalt concrete, cold in-place asphalt recycling, and polymer modification of asphalt pavements in Ontario. The last two papers were presented in a session on relationship of materials characterization to accelerated pavement performance testing.

  13. Evaluation of a highway pavement using non destructive tests: Falling Weight Deflectometer and Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Marecos, Vania; Fontul, Simona; de Lurdes Antunes, Maria

    2015-04-01

    This paper presents the results of the application of Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) to assess the bearing capacity of a rehabilitated flexible highway pavement that began to show the occurrence of cracks in the surface layer, about one year after the improvement works. A visual inspection of the surface of the pavement was performed to identify and characterize the cracks. Several core drills were done to analyse the cracks propagation in depth, these cores were also used for GPR data calibration. From the visual inspection it was concluded that the development of the cracks were top-down and that the cracks were located predominantly in the wheel paths. To determine the thickness of the bituminous and granular layers GPR tests were carried out using two horn antennas of 1,0 GHz and 1,8 GHz and a radar control unit SIR-20, both from GSSI. FWD load tests were performed on the wheel paths and structural models were established, based on the deflections measured, through back calculation. The deformation modulus of the layers was calculated and the bearing capacity of the pavement was determined. Summing up, within this study the GPR was used to continuously detect the layer thickness and the GPR survey data was calibrated with core drills. The results showed variations in the bituminous layer thickness in comparison to project data. From the load tests it was concluded that the deformation modulus of the bituminous layers were also vary variable. Limitations on the pavement bearing capacity were detected in the areas with the lower deformation modulus. This abstract is of interest for COST Action TU1208 Civil Engineering Applications of Ground Penetrating Radar.

  14. Enhanced Performance in Flexible Binder-free SWCNT Membrane EDLC

    NASA Astrophysics Data System (ADS)

    Ma, Danhao; Shetty, Pralav; Adu, Kofi; Rajagopalan, Ramakrishnan

    2013-03-01

    We present results on an aqueous symmetric double layer electrochemical capacitor (EDLC) constructed with flexible binder-free single wall carbon (SWCNTs) membrane as electrodes. The capacitors were cycled from 0 to 1V @ 10 A/g for 10,000 cycles with 99.9% coulombic efficiency and 94% energy efficiency, and 100% depth of discharge. The power performance of the aqueous symmetric SWCNTs membrane capacitor is almost 100 -1000 times better than commercial non-aqueous EDLC capacitors. This work is supported by the Pennsylvania State, Altoona College Undergraduate Research Program and the Pennsylvania State Materials Research Institute at University Park, PA

  15. 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

    EPA Science Inventory

    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...

  16. Environmental assessment of pavement infrastructure: A systematic review.

    PubMed

    Inyim, Peeraya; Pereyra, Jose; Bienvenu, Michael; Mostafavi, Ali

    2016-07-01

    Through a critical review and systematic analysis of pavement life cycle assessment (LCA) studies published over the past two decades, this study shows that the available information regarding the environmental impacts of pavement infrastructure is not sufficient to determine what pavement type is more environmentally sustainable. Limitations and uncertainties related to data, system boundary and functional unit definitions, consideration of use and maintenance phase impacts, are identified as the main reasons for inconsistency of reported results in pavement LCA studies. The study outcomes also highlight the need for advancement of knowledge pertaining to: (1) utilization of performance-adjusted functional units, (2) accurate estimation of use, maintenance, and end-of-life impacts, (3) incorporation of the dynamic and uncertain nature of pavement condition performance in impact assessment; (4) development of region-specific inventory data for impact estimation; and (5) consideration of a standard set of impact categories for comparison of environmental performance of different pavement types. Advancing the knowledge in these areas is critical in providing consistent and reliable results to inform decision-making toward more sustainable roadway infrastructure. PMID:27045541

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

    PubMed

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

    2013-12-15

    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

  18. Field performance of maintenance treatments constructed with reclaimed asphalt pavement (RAP). Final research report, September 1992-August 1994

    SciTech Connect

    Estakhri, C.K.

    1994-11-01

    In the study, RAP was blended with recycling emulsions and conventional maintenance mixtures in attempts to improve its field performance as a maintenance mixture. RAP was also mixed with stabilizers and used as a base material in maintenance projects. Several field experiments were constructed throughout the state, and the report documents their performance.

  19. Semiconducor wires and ribbons for high performance flexible electronics.

    SciTech Connect

    Sun, Y.; Baca, A. J.; Ahn, J.-H.; Meitl, M.; Menard, E.; Kim, H.-S; Choi, W.; Kim, D.-H; Huang, Y.; Rogers, J. A.; Center for Nanoscale Materials; Univ. of Illinois

    2008-01-01

    This article reviews the properties, fabrication and assembly of inorganic semiconductor materials that can be used as active building blocks to form high-performance transistors and circuits for flexible and bendable large-area electronics. Obtaining high performance on low temperature polymeric substrates represents a technical challenge for macroelectronics. Therefore, the fabrication of high quality inorganic materials in the form of wires, ribbons, membranes, sheets, and bars formed by bottom-up and top-down approaches, and the assembly strategies used to deposit these thin films onto plastic substrates will be emphasized. Substantial progress has been made in creating inorganic semiconducting materials that are stretchable and bendable, and the description of the mechanics of these form factors will be presented, including circuits in three-dimensional layouts. Finally, future directions and promising areas of research will be described.

  20. Performance analysis of flexible aircraft with active control

    NASA Technical Reports Server (NTRS)

    Noll, R. B.; Morino, L.

    1976-01-01

    Small perturbation equations of motion of a flexible aircraft with an active control technology (ACT) system were developed to evaluate the stability and performance of the controlled aircraft. The total aircraft system was formulated in state vector format and the system of equations was completed with fully unsteady and low frequency aerodynamics for arbitrary, complex configurations based on a potential aerodynamic method. The ACT system equations were incorporated in the digital computer program FCAP (Flight Control Analysis Program) which can be used for the analysis of complete aircraft configurations, including control system, with either low frequency or fully unsteady aerodynamics. The application of classical performance analyses including frequency response, poles and zeros, mean square response, and time response in FCAP in state vector format was discussed.

  1. Fatigue behavior of rubber modified pavements. Final report, 1994-1996

    SciTech Connect

    Raad, L.; Saboundjian, S.

    1997-05-01

    Over the last 15 years, a number of rubberized pavement projects have been built in Alaska. Initial laboratory and field investigations sponsored by the Alaska Department of Transportation and Public Facilities (AKDOT&PF) and conducted by Raad et al. (1995) indicated improved fatigue performance of the rubberized sections in comparison with conventional asphalt concrete pavements. The report presents the results of a follow-up investigation to develop design equations for rubberized pavements in Alaska.

  2. Developing Flexible, High Performance Polymers with Self-Healing Capabilities

    NASA Technical Reports Server (NTRS)

    Jolley, Scott T.; Williams, Martha K.; Gibson, Tracy L.; Caraccio, Anne J.

    2011-01-01

    Flexible, high performance polymers such as polyimides are often employed in aerospace applications. They typically find uses in areas where improved physical characteristics such as fire resistance, long term thermal stability, and solvent resistance are required. It is anticipated that such polymers could find uses in future long duration exploration missions as well. Their use would be even more advantageous if self-healing capability or mechanisms could be incorporated into these polymers. Such innovative approaches are currently being studied at the NASA Kennedy Space Center for use in high performance wiring systems or inflatable and habitation structures. Self-healing or self-sealing capability would significantly reduce maintenance requirements, and increase the safety and reliability performance of the systems into which these polymers would be incorporated. Many unique challenges need to be overcome in order to incorporate a self-healing mechanism into flexible, high performance polymers. Significant research into the incorporation of a self-healing mechanism into structural composites has been carried out over the past decade by a number of groups, notable among them being the University of I1linois [I]. Various mechanisms for the introduction of self-healing have been investigated. Examples of these are: 1) Microcapsule-based healant delivery. 2) Vascular network delivery. 3) Damage induced triggering of latent substrate properties. Successful self-healing has been demonstrated in structural epoxy systems with almost complete reestablishment of composite strength being achieved through the use of microcapsulation technology. However, the incorporation of a self-healing mechanism into a system in which the material is flexible, or a thin film, is much more challenging. In the case of using microencapsulation, healant core content must be small enough to reside in films less than 0.1 millimeters thick, and must overcome significant capillary and surface tension forces to flow, mix and react to achieve healing. Vascular networks small enough to fit into such films must also overcome these same flow limitations. Self-healing has also been demonstrated in ionomeric substrates such as Surlyn , wherein the heat generated by a projectile impact triggers the latent ability of this substrate to flow back to its original shape. Recent work using Diels-Alder reactions have shown promise in bringing about actual reforming of broken chemical bonds to achieve self-healing [2]. All self-healing mechanisms that rely on the use of inherent latent substrate properties require some degree of polymer chain flow to achieve any significant level of healing.

  3. Pavement recycling. Executive summary and report

    SciTech Connect

    1995-10-01

    The Federal Highway Administration (FHWA) initiated Demonstration Project 39 (DP 39) Recycling Asphalt Pavements in June 1976. The project showed that asphalt pavement recycling was a technically viable rehabitation technique, and it was estimated that the use of reclaimed asphalt pavement (RAP) would amount to approximately 15 percent of the total hot-mix asphalt (HMA) production by the mid-1980s. It was expected that most of the asphalt pavement removed would be reused in new pavement construction or overlays.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  5. Performance and system flexibility of the CDF Hardware Event Builder

    SciTech Connect

    Shaw, T.M.; Schurecht, K. ); Sinervo, P. . Dept. of Physics)

    1991-11-01

    The CDF Hardware Event Builder (1) is a flexible system which is built from a combination of three different 68020-based single width Fastbus modules. The system may contain as few as three boards or as many as fifteen, depending on the specific application. Functionally, the boards receive a command to read out the raw event data from a set of Fastbus based data buffers ( scanners''), reformat data and then write the data to a Level 3 trigger/processing farm which will decide to throw the event away or to write it to tape. The data acquisition system at CDF will utilize two nine board systems which will allow an event rate of up to 35 Hz into the Level 3 trigger. This paper will present detailed performance factors, system and individual board architecture, and possible system configurations.

  6. Performance and system flexibility of the CDF Hardware Event Builder

    SciTech Connect

    Shaw, T.M.; Schurecht, K.; Sinervo, P.

    1991-11-01

    The CDF Hardware Event Builder [1] is a flexible system which is built from a combination of three different 68020-based single width Fastbus modules. The system may contain as few as three boards or as many as fifteen, depending on the specific application. Functionally, the boards receive a command to read out the raw event data from a set of Fastbus based data buffers (``scanners``), reformat data and then write the data to a Level 3 trigger/processing farm which will decide to throw the event away or to write it to tape. The data acquisition system at CDF will utilize two nine board systems which will allow an event rate of up to 35 Hz into the Level 3 trigger. This paper will present detailed performance factors, system and individual board architecture, and possible system configurations.

  7. High-performance flexible microwave passives on plastic

    NASA Astrophysics Data System (ADS)

    Ma, Zhenqiang; Seo, Jung-Hun; Cho, Sang June; Zhou, Weidong

    2014-06-01

    We report the demonstration of bendable inductors, capacitors and switches fabricated on a polyethylene terephthalate (PET) substrate that can operate at high microwave frequencies. By employing bendable dielectric and single crystalline semiconductor materials, spiral inductors and metal-insulator-metal (MIM) capacitors with high quality factors and high resonance frequencies and single-pole, single-throw (SPST) switches were archived. The effects of mechanical bending on the performance of inductors, capacitors and switches were also measured and analyzed. We further investigated the highest possible resonance frequencies and quality factors of inductors and capacitors and, high frequency responses and insertion loss. These demonstrations will lead to flexible radio-frequency and microwave systems in the future.

  8. Small-scale accelerated pavement testing

    SciTech Connect

    Kim, S.M.; Hugo, F.; Roesset, J.M.

    1998-03-01

    This paper presents the results of a study conducted to explore the use of small-scale models of accelerated pavement testing (APT) devices to evaluate the performance of pavements in conjunction with full-scale tests. The motivation for the study was the availability of a model mobile load simulator (MMLS), which had been built originally to illustrate the operation of the full-scale mobile load simulator (MLS) under design at the time. The scaling requirements will be different depending on whether dynamic (inertia), viscous, or gravity effects are important. One must thus decide which one of these effects controls the behavior to try to reproduce it exactly. In the preliminary tests conducted with the MMLS, emphasis had been placed in reproducing accurately the viscoelastic behavior of the asphalt layer. The possibility of obtaining valid results, even if similitude is not maintained in relation to inertia forces, is explored in this paper. The effects of load frequency or velocity and the effects of layer thicknesses are studied. The total thickness of the model pavement, which must be finite, and its effects on displacements and strains are also considered. It is concluded that even when full similitude is not satisfied it is possible to obtain valid results that can be extrapolated to predict prototype performance if one were interested primarily in the behavior of the asphalt layer. Preliminary analyses should be conducted, however, to guide on the selection of the model dimensions.

  9. Optical performance monitoring for dynamic and flexible photonic networks

    NASA Astrophysics Data System (ADS)

    Oda, Shoichiro; Yang, Jeng-Yuan; Akasaka, Youichi; Vassilieva, Olga; Yamauchi, Tomohiro; Aoki, Yasuhiko; Sekiya, Motoyoshi; Rasmussen, Jens C.

    2015-01-01

    Optical performance monitoring (OPM) is considered as an important tool in order to operate and manage dynamic, flexible, and thus complex photonic networks. In this paper, firstly we review recent studies on OPM and discuss its possible applications, such as failure diagnosis of transmitter, receiver, and other transport equipment, optimization of system reach design, and so on. We then present two different types of in-band OSNR monitor, consisting of an optical bandpass filter, a photo-detector, and a signal processer. Since the proposed monitor might be realized by the same hardware implementation as an optical channel monitor (OCM), this is potentially integrated with an OCM in a low-cost fashion. We also explain a BER monitor, which is realized by the same hardware configuration as the above in-band OSNR monitor. The BER in the method is estimated by monitoring OSNR including nonlinear noise as noise source and taking the imperfection of Tx, Rx, and other equipment into account. Finally we develop FPGA-based optical performance monitor prototype and experimentally demonstrate successful monitoring performance.

  10. Pavement management using hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Ayalew, Balehager; Gomez, Richard B.; Roper, William E.; Carrasco, Oscar

    2003-08-01

    Public Works facilities require up-to-date information on the health status of the road network they maintain. However, roadway maintenance and rehabilitation involves the greatest portion of a municipality's annual operating budget. Government officials use various technologies such as a pavement management system to assist in making better decisions about their roadways systems, pavement condition, history, and projects. Traditionally, manual surveying has served as the method of obtaining this information. To better assist in decision-making, a regionally specific spectral library for urban areas is being developed and used in conjunction with hyperspecrtal imaging, to map urban materials and pavement conditions. A Geographical Information and Positioning System (GIS/GPS) will also be implemented to overlay relative locations. This paper will examine the benefits of using hyperspectral imaging over traditional methods of roadway maintenance and rehabilitation for pavement management applications. In doing so, we will identify spatial and spectral requirements for successful large-scale road feature extraction.

  11. Pervious Pavement System Evaluation- Abstract

    EPA Science Inventory

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

  12. Mechanically Flexible and High-Performance CMOS Logic Circuits

    NASA Astrophysics Data System (ADS)

    Honda, Wataru; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

    2015-10-01

    Low-power flexible logic circuits are key components required by the next generation of flexible electronic devices. For stable device operation, such components require a high degree of mechanical flexibility and reliability. Here, the mechanical properties of low-power flexible complementary metal-oxide-semiconductor (CMOS) logic circuits including inverter, NAND, and NOR are investigated. To fabricate CMOS circuits on flexible polyimide substrates, carbon nanotube (CNT) network films are used for p-type transistors, whereas amorphous InGaZnO films are used for the n-type transistors. The power consumption and voltage gain of CMOS inverters are <500 pW/mm at Vin = 0 V (<7.5 nW/mm at Vin = 5 V) and >45, respectively. Importantly, bending of the substrate is not found to cause significant changes in the device characteristics. This is also observed to be the case for more complex flexible NAND and NOR logic circuits for bending states with a curvature radius of 2.6 mm. The mechanical stability of these CMOS logic circuits makes them ideal candidates for use in flexible integrated devices.

  13. Mechanically Flexible and High-Performance CMOS Logic Circuits.

    PubMed

    Honda, Wataru; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

    2015-01-01

    Low-power flexible logic circuits are key components required by the next generation of flexible electronic devices. For stable device operation, such components require a high degree of mechanical flexibility and reliability. Here, the mechanical properties of low-power flexible complementary metal-oxide-semiconductor (CMOS) logic circuits including inverter, NAND, and NOR are investigated. To fabricate CMOS circuits on flexible polyimide substrates, carbon nanotube (CNT) network films are used for p-type transistors, whereas amorphous InGaZnO films are used for the n-type transistors. The power consumption and voltage gain of CMOS inverters are <500 pW/mm at Vin = 0 V (<7.5 nW/mm at Vin = 5 V) and >45, respectively. Importantly, bending of the substrate is not found to cause significant changes in the device characteristics. This is also observed to be the case for more complex flexible NAND and NOR logic circuits for bending states with a curvature radius of 2.6 mm. The mechanical stability of these CMOS logic circuits makes them ideal candidates for use in flexible integrated devices. PMID:26459882

  14. Mechanically Flexible and High-Performance CMOS Logic Circuits

    PubMed Central

    Honda, Wataru; Arie, Takayuki; Akita, Seiji; Takei, Kuniharu

    2015-01-01

    Low-power flexible logic circuits are key components required by the next generation of flexible electronic devices. For stable device operation, such components require a high degree of mechanical flexibility and reliability. Here, the mechanical properties of low-power flexible complementary metal–oxide–semiconductor (CMOS) logic circuits including inverter, NAND, and NOR are investigated. To fabricate CMOS circuits on flexible polyimide substrates, carbon nanotube (CNT) network films are used for p-type transistors, whereas amorphous InGaZnO films are used for the n-type transistors. The power consumption and voltage gain of CMOS inverters are <500 pW/mm at Vin = 0 V (<7.5 nW/mm at Vin = 5 V) and >45, respectively. Importantly, bending of the substrate is not found to cause significant changes in the device characteristics. This is also observed to be the case for more complex flexible NAND and NOR logic circuits for bending states with a curvature radius of 2.6 mm. The mechanical stability of these CMOS logic circuits makes them ideal candidates for use in flexible integrated devices. PMID:26459882

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

    NASA Astrophysics Data System (ADS)

    Yati Katman, Herda; Rasdan Ibrahim, Mohd; Yazip Matori, Mohd; Norhisham, Shuhairy; Ismail, Norlela

    2013-06-01

    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.

  16. Evaluation of Surface and Subsurface Processes in Permeable Pavement Infiltration Trenches

    EPA Science Inventory

    The hydrologic performance of permeable pavement systems can be affected by clogging of the pavement surface and/or clogging at the interface where the subsurface storage layer meets the underlying soil. As infiltration and exfiltration are the primary functional mechanisms for ...

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

    PubMed

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

    2014-06-15

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

  18. Simultaneous Production of High-Performance Flexible Textile Electrodes and Fiber Electrodes for Wearable Energy Storage.

    PubMed

    Dong, Liubing; Xu, Chengjun; Li, Yang; Wu, Changle; Jiang, Baozheng; Yang, Qian; Zhou, Enlou; Kang, Feiyu; Yang, Quan-Hong

    2016-02-01

    High-performance flexible textile electrodes and fiber electrodes are produced simultaneously by a newly proposed effective strategy. Activated carbon fiber cloth (ACFC)/carbon nanotubes (CNTs) and ACFC/MnO2 /CNTs composites are designed as high-performance flexible textile electrodes. Theses textiles can also be easily dismantled into individual fiber bundles used as high-performance flexible fiber electrodes. PMID:26679519

  19. MTG Flexible Combined Imager optical design and performances

    NASA Astrophysics Data System (ADS)

    Ouaknine, J.; Gode, S.; Napierala, B.; Viard, T.; Foerster, U.; Fray, S.; Peacoke, Patrick; Hartl, M.; Hallibert, P.; Durand, Y.

    2013-09-01

    Meteosat Third Generation is the next ESA Program of Earth Observation dedicated to Nowcasting and very short term Weather Forecasting (NWC), medium/short range Global and Regional Numerical Weather Prediction (NWP), and Climate and Air Composition Monitoring. The satellites will be operating from the Geostationary orbit using a 3 axes stabilized platform. The main instrument is called the Flexible Combined Imager (FCI), currently under development by Thales Alenia Space France (TAS-F). This instrument will provide full images of the Earth every 10 minutes in 16 spectral channels between 0.44 and 13.3 μm, with a ground resolution from 0.5 km to 2 km. The FCI is composed of a TMA telescope developed by Kayser-Threde (KT), which includes a Scan mirror, and a calibration mechanism with an embedded black body dedicated to accurate in-flight IR radiometric calibration and a Metallic Neutral density for dedicated VNIR Sun calibration. The image produced by the telescope is split into several spectral groups by a spectral separation assembly (SSA) with dichroïc beamsplitters. The output beams are collimated to ease the instrument integration, and reach the cold optics (CO-I) which focalize the optical beams onto the detectors. The cold optics and IR detectors are accurately positioned inside a common cryostat to improve registration between spectral channels. Spectral filters are integrated on top of the detectors in order to achieve the required spectral selection. This article will describe the optical design and the main optical performances of the FCI: image quality, very high line-of-sight stability, and an efficient stray-light rejection thanks to the implementation of dedicated baffles and a stringent control of contamination. The FCI currently under development is expected to exhibit a significant improvement of performances with respect to Meteosat Second Generation satellites.

  20. The Relationship Between of Manufacturing Flexibility, Innovation Capability, and Operational Performance in Indonesian Manufacturing SMEs

    NASA Astrophysics Data System (ADS)

    Purwanto, U. S.; Raihan

    2016-02-01

    This study examined the relationship between manufacturing flexibility competence and operational performance with technological innovation capability as mediator variables. A survey method was applied to collect data pertaining to the variables being investigated. The findings indicated that manufacturing flexibility competence is positively associated with technological innovation capability and operational performance. The findings also suggested that technological innovation capability types mediated positively to the operational performance implication of manufacturing flexibility competence. This implies that manufacturing organizations pursuing manufacturing flexibility competence need to develop technological innovation capability in obtaining a high operational performance.

  1. Pervious Pavement System Evaluation-Poster

    EPA Science Inventory

    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...

  2. Quantifying Evaporation in a Permeable Pavement System

    EPA Science Inventory

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

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

    NASA Astrophysics Data System (ADS)

    Loizos, Andreas; Plati, Christina

    2014-05-01

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

  4. Fatigue properties of rubber modified pavements. Final report

    SciTech Connect

    Raad, L.; Saboundjian, S.; Yuan, X.

    1995-05-01

    This report presents results of a study to determine the fatigue behavior of rubber modified pavements in Alaska in comparison with conventional asphalt concrete pavements. Laboratory studies were conducted on field specimens using the flexural fatigue test in the controlled-displacement mode. Tests were performed at 72 deg F and 40 deg F. Tested materials include (1) conventional HMA with AC 2.5 and AC 5; (2) PlusRide RUMAC with AC 5; (3) asphalt-rubber concrete with AC 2.5 (wet Process); and (4) rubberized asphalt-rubber concrete with AC 2.5 (wet/dry process).

  5. Pavement thickness evaluation using ground penetrating radar

    NASA Astrophysics Data System (ADS)

    Harris, Dwayne Arthur

    Accurate knowledge of pavement thickness is important information to have both at a network and project level. This information aids in pavement management and design. Much of the time this information is missing, out of date, or unknown for highway sections. Current technologies for determining pavement thickness are core drilling, falling weight deflectometer (FWD), and ground penetrating radar (GPR). Core drilling provides very accurate pin point pavement thickness information; however, it is also time consuming, labor intensive, intrusive to traffic, destructive, and limited in coverage. FWD provides nondestructive estimates of both a surface thickness and total pavement structure thickness, including pavement, base and sub-base. On the other hand, FWD is intrusive to traffic and affected by the limitations and assumptions the method used to estimate thickness. GPR provides pavement surface course thickness estimates with excellent data coverage at highway speed. Yet, disadvantages include the pavement thickness estimation being affected by the electrical properties of the pavement, limitations of the system utilized, and heavy post processing of the data. Nevertheless, GPR has been successfully utilized by a number of departments of transportation (DOTs) for pavement thickness evaluation. This research presents the GPR thickness evaluation methods, develops GPRPAVZ the software used to implement the methodologies, and addresses the quality of GPR pavement thickness evaluation.

  6. Analysis of Load Stress for Asphalt Pavement of Lean Concrete Base

    NASA Astrophysics Data System (ADS)

    Lijun, Suo; Xinwu, Wang

    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.

  7. The Concrete and Pavement Challenge

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2012-01-01

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

  8. The Concrete and Pavement Challenge

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2012-01-01

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

  9. Pavement recycling guidelines for state and local governments: Participant`s reference book. Final report, September 1995--December 1997

    SciTech Connect

    Kandhal, P.S.; Mallick, R.B.

    1997-12-01

    Recycling or reuse of existing asphalt pavement materials to produce new pavement materials has the following advantages: (1) reduced costs of construction, (2) conservation of aggregate and binder, (3) preservation of the existing pavement geometrics, (4) preservation of the environment, and (5) conservation of energy. This document was prepared to provide the following information on recycling of asphalt pavements: (1) performance data, (2) legislation/specification limits, (3) selection of pavement for recycling and recycling strategies, (4) economics of recycling, and (5) structural design of recycled pavements. The following recycling methods have been included: hot-mix asphalt recycling (both batch and drum plants), asphalt surface recycling, hot-in-place recycling, cold-mix asphalt recycling, and full depth reclamation. Materials and mix design, construction methods and equipment, case histories and quality control/quality assurance have been discussed for all recycling methods.

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

    NASA Astrophysics Data System (ADS)

    Injun, Song

    2015-04-01

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

  11. Measuring Clogging with Pressure Transducers in Permeable Pavement Strips

    EPA Science Inventory

    Two issues that have a negative affect on the long term hydrologic performance of permeable pavement systems are surface clogging and clogging at the interface with the underlying soil. Surface clogging limits infiltration capacity and results in bypass if runoff rate exceeds in...

  12. Monitoring Strategies in Permeable Pavement Systems to Optimize Maintenance Scheduling

    EPA Science Inventory

    As the surface in a permeable pavement system clogs and performance decreases, maintenance is required to preserve the design function. Currently, guidance is limited for scheduling maintenance on an as needed basis. Previous research has shown that surface clogging in a permea...

  13. Flexible Carbon Nanotube Films for High Performance Strain Sensors

    PubMed Central

    Kanoun, Olfa; Müller, Christian; Benchirouf, Abderahmane; Sanli, Abdulkadir; Dinh, Trong Nghia; Al-Hamry, Ammar; Bu, Lei; Gerlach, Carina; Bouhamed, Ayda

    2014-01-01

    Compared with traditional conductive fillers, carbon nanotubes (CNTs) have unique advantages, i.e., excellent mechanical properties, high electrical conductivity and thermal stability. Nanocomposites as piezoresistive films provide an interesting approach for the realization of large area strain sensors with high sensitivity and low manufacturing costs. A polymer-based nanocomposite with carbon nanomaterials as conductive filler can be deposited on a flexible substrate of choice and this leads to mechanically flexible layers. Such sensors allow the strain measurement for both integral measurement on a certain surface and local measurement at a certain position depending on the sensor geometry. Strain sensors based on carbon nanostructures can overcome several limitations of conventional strain sensors, e.g., sensitivity, adjustable measurement range and integral measurement on big surfaces. The novel technology allows realizing strain sensors which can be easily integrated even as buried layers in material systems. In this review paper, we discuss the dependence of strain sensitivity on different experimental parameters such as composition of the carbon nanomaterial/polymer layer, type of polymer, fabrication process and processing parameters. The insights about the relationship between film parameters and electromechanical properties can be used to improve the design and fabrication of CNT strain sensors. PMID:24915183

  14. Performance characterization of flexible dipole rectennas for smart actuator use

    NASA Astrophysics Data System (ADS)

    Kim, Jaehwan; Yang, Sang Yeol; Song, Kyo D.; Jones, Sean; Choi, Sang H.

    2006-06-01

    The concept of power transmission by a microwave is envisioned as the best option for alleviating the complexity associated with hard-wired control circuitry in controlling smart actuators and robots such as micro-aerial vehicles, biomimetic robots and space vehicles to produce remotely maneuverable capability. A flexible dipole rectenna array is conformably adaptable on the complex structure of vehicles used for practical applications of wireless power. For these applications, various flexible dipole rectennas and arrays were designed, fabricated and characterized over a frequency range of 9-12 GHz with 20 W and 200 W amplifiers through laboratory testing. The irradiance of the microwave power was measured. Also the irradiated power, the output power and the efficiency of the rectenna arrays were evaluated along with the microwave power and frequency. The maximum voltage of 65 VDC was observed from a series connected dipole rectenna array and the maximum current of 2.50 mA was obtained from a parallel connected rectenna array. The efficiency of dipole rectenna arrays ranges from 20% to 50% depending on the input power and the pole configuration. It was also demonstrated that the voltage, current and power output from a dipole rectenna array can be tailored by configuring the dipole rectenna elements in serial and parallel mode connections.

  15. Performance improvement of bandwidth-flexible reconfigurable optical add/drop multiplexers with wavelength converters

    NASA Astrophysics Data System (ADS)

    You, S.

    2011-12-01

    In this paper, we propose a novel bandwidth-flexible reconfigurable optical add/drop multiplexer (ROADM) architecture based on coherent optical-orthogonal frequency division multiplexing (CO-OFDM) technology. The bandwidth-flexible ROADM architecture enables sub-wavelength, superwavelength, and multiple-rate data traffic accommodation in a highly spectrum-efficient manner, thereby providing a fractional bandwidth service. We simulate and compare the blocking performance of bandwidth-flexible ROADM with and without wavelength converters. It is found that wavelength converter could obviously improve the blocking performance of bandwidth-flexible ROADM with different frequency grid. Moreover, the conversion ratios are calculated for different load and channel spacing. Based on the analysis of conversion ratio, we could make an appropriate configuration of wavelength converters in bandwidth-flexible ROADM.

  16. High temperature performance of flexible thermal protection materials

    NASA Technical Reports Server (NTRS)

    Savage, R. T.; Love, W.; Bloetscher, F.

    1984-01-01

    Aero convective tests of several flexible thermal protection system (FTPS) concepts were conducted in the NASA Ames Research Center 20 MW arcjet aero heating wind tunnel. The concepts consisted of quilted insulation blankets with nextel AB312 felt insulation stitched between cover cloths with AB312 thread. The cover cloths were commercially available nextel AB312 and nicalon fabrics. The specimens were subjected to convective heat fluxes ranging from 7 to 35 Btu/per sq ft per sec at stagnation pressures of .005 to .02 atm. Specimens were tested both with and without transpiration cooling. Results indicated that both the nextel and nicalon fabrics offer the potential for higher temperature applications than current FTPS, and nicalon appears to be capable of withstanding temperatures well above 2500 degrees F with minimal degradation.

  17. Use of Time Domain Reflectometers (TDRs) in Permeable Pavement Systems to Predict Maintenance Needs and Effectiveness

    EPA Science Inventory

    As the surface in permeable pavement systems clogs, infiltration capacity decreases, so maintenance is required to maintain hydrologic performance. There is limited direct guidance for determining when maintenance is needed to prevent surface runoff bypass. Research is being co...

  18. Pollutant load removal efficiency of pervious pavements: is clogging an issue?

    PubMed

    Kadurupokune, N; Jayasuriya, N

    2009-01-01

    Pervious pavements in car parks and driveways reduce the peak runoff rate and the quantity of runoff discharged into urban drains as well as improve the stormwater quality by trapping the sediments in the infiltrated water. The paper focuses on presenting results from the laboratory tests carried out to evaluate water quality improvements and effects of long-term decrease in infiltration rates with time due to sediments trapping (clogging) within the pavement pores. Clogging was not found to be a major factor affecting pervious pavement performance after simulating 17 years of stormwater quality samples. PMID:19809141

  19. Evaluation Model for Pavement Surface Distress on 3d Point Clouds from Mobile Mapping System

    NASA Astrophysics Data System (ADS)

    Aoki, K.; Yamamoto, K.; Shimamura, H.

    2012-07-01

    This paper proposes a methodology to evaluate the pavement surface distress for maintenance planning of road pavement using 3D point clouds from Mobile Mapping System (MMS). The issue on maintenance planning of road pavement requires scheduled rehabilitation activities for damaged pavement sections to keep high level of services. The importance of this performance-based infrastructure asset management on actual inspection data is globally recognized. Inspection methodology of road pavement surface, a semi-automatic measurement system utilizing inspection vehicles for measuring surface deterioration indexes, such as cracking, rutting and IRI, have already been introduced and capable of continuously archiving the pavement performance data. However, any scheduled inspection using automatic measurement vehicle needs much cost according to the instruments' specification or inspection interval. Therefore, implementation of road maintenance work, especially for the local government, is difficult considering costeffectiveness. Based on this background, in this research, the methodologies for a simplified evaluation for pavement surface and assessment of damaged pavement section are proposed using 3D point clouds data to build urban 3D modelling. The simplified evaluation results of road surface were able to provide useful information for road administrator to find out the pavement section for a detailed examination and for an immediate repair work. In particular, the regularity of enumeration of 3D point clouds was evaluated using Chow-test and F-test model by extracting the section where the structural change of a coordinate value was remarkably achieved. Finally, the validity of the current methodology was investigated by conducting a case study dealing with the actual inspection data of the local roads.

  20. Mites from the city pavement.

    PubMed

    Samsinák, K; Vobrázková, E

    1985-06-01

    The authors obtained a total of 136 mite specimens from dust samples collected from the pavement of Prague in monthly intervals for a period of one year. Of utmost importance was the finding of Dermatophagoides farinae Hughes, 1961 and Euroglyphus maynei (Cooreman, 1950), both of the family Pyroglyphidae, allergogenic mites. Apart from a few exceptions, all other species were common mites of food stores. PMID:4050178

  1. Evaluating Pavement Cracks with Bidimensional Empirical Mode Decomposition

    NASA Astrophysics Data System (ADS)

    Ayenu-Prah, Albert; Attoh-Okine, Nii

    2008-12-01

    Crack evaluation is essential for effective classification of pavement cracks. Digital images of pavement cracks have been analyzed using techniques such as fuzzy set theory and neural networks. Bidimensional empirical mode decomposition (BEMD), a new image analysis method recently developed, can potentially be used for pavement crack evaluation. BEMD is an extension of the empirical mode decomposition (EMD), which can decompose nonlinear and nonstationary signals into basis functions called intrinsic mode functions (IMFs). IMFs are monocomponent functions that have well-defined instantaneous frequencies. EMD is a sifting process that is nonparametric and data driven; it does not depend on an a priori basis set. It is able to remove noise from signals without complicated convolution processes. BEMD decomposes an image into two-dimensional IMFs. The present paper explores pavement crack detection using BEMD together with the Sobel edge detector. A number of images are filtered with BEMD to remove noise, and the residual image analyzed with the Sobel edge detector for crack detection. The results are compared with results from the Canny edge detector, which uses a Gaussian filter for image smoothing before performing edge detection. The objective is to qualitatively explore how well BEMD is able to smooth an image for more effective edge detection with the Sobel method.

  2. High-performance green flexible electronics based on biodegradable cellulose nanofibril paper

    NASA Astrophysics Data System (ADS)

    Jung, Yei Hwan; Chang, Tzu-Hsuan; Zhang, Huilong; Yao, Chunhua; Zheng, Qifeng; Yang, Vina W.; Mi, Hongyi; Kim, Munho; Cho, Sang June; Park, Dong-Wook; Jiang, Hao; Lee, Juhwan; Qiu, Yijie; Zhou, Weidong; Cai, Zhiyong; Gong, Shaoqin; Ma, Zhenqiang

    2015-05-01

    Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials.

  3. High-performance green flexible electronics based on biodegradable cellulose nanofibril paper

    PubMed Central

    Jung, Yei Hwan; Chang, Tzu-Hsuan; Zhang, Huilong; Yao, Chunhua; Zheng, Qifeng; Yang, Vina W.; Mi, Hongyi; Kim, Munho; Cho, Sang June; Park, Dong-Wook; Jiang, Hao; Lee, Juhwan; Qiu, Yijie; Zhou, Weidong; Cai, Zhiyong; Gong, Shaoqin; Ma, Zhenqiang

    2015-01-01

    Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials. PMID:26006731

  4. High-performance green flexible electronics based on biodegradable cellulose nanofibril paper.

    PubMed

    Jung, Yei Hwan; Chang, Tzu-Hsuan; Zhang, Huilong; Yao, Chunhua; Zheng, Qifeng; Yang, Vina W; Mi, Hongyi; Kim, Munho; Cho, Sang June; Park, Dong-Wook; Jiang, Hao; Lee, Juhwan; Qiu, Yijie; Zhou, Weidong; Cai, Zhiyong; Gong, Shaoqin; Ma, Zhenqiang

    2015-01-01

    Today's consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials. PMID:26006731

  5. Preliminary evaluation of LTPP continuously reinforced concrete (CRC) pavement test sections. Final report, February 1995--October 1998

    SciTech Connect

    Tayabji, S.D.; Selezneva, O.; Jiang, Y.J.

    1999-07-01

    As part of the study reported here, analysis of data from the LTPP GPS-5 test sections was conducted to identify factors that influence long-term crack spacing in continuously reinforced concrete (CRC) pavements and to determine that effect of crack spacing on pavement performance. Data from the 85 test sections from the GPS-5 experiment were analyzed.

  6. Recycling of water-susceptible pavements

    NASA Astrophysics Data System (ADS)

    Maupin, G. W.

    1980-05-01

    Several bituminous concrete interstate pavements that experienced failures suspected to have been caused by stripping were investigated. On two projects, the degree of deterioration, potential serviceability, and possible remedial measures were studied. Cores were taken to determine the degreee of stripping and tensile strength, and dynaflect tests were performed. An emulsion mix design was developed for stripped bituminous concrete removed from another project with the expectation that it could be used as a surface mix on a highway with a low traffic volume. While this expectation was not realized, it was concluded that the material is suitable for use in a base mix. A maintenance resurfacing on a fourth project that experienced stripping failure is being monitored and the performance is being evaluated.

  7. Investigation of mechanical properties of pavement through electromagnetic techniques

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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

  8. Investigation and application of fractured slab techniques for PCC pavements. Final report, May 1996--April 1999

    SciTech Connect

    Owusu-Ababio, S.; Nelson, T.

    1999-04-01

    Slab fracture techniques, including break and seat, crack and seat, and rubblization have in recent years gained widespread recognition among pavement engineers as means for eliminating or substantially reducing the potential for reflective cracking in hot mix asphalt (HMA) overlays over portland cement concrete (PCC) pavements. Guidelines for the use of these techniques in Wisconsin, however, have not been clearly established. This reports examines the PCC rehabilitation techniques of rubblization and crack and seat used in Wisconsin and their performance. The report examines the literature and evaluates the critical issues associated with the use of PCC fracture techniques by various agencies. Several elements pertinent to fracture techniques are also identified and incorporated in a database for in-service fractured overlaid PCC pavements in Wisconsin. In addition, the in-service performance of cracked and seated and rubblized pavements in Wisconsin is evaluated.

  9. Flexibility effects on the control system performance of large scale robotic manipulators

    NASA Technical Reports Server (NTRS)

    Cetinkunt, Sabri; Book, Wayne J.

    1990-01-01

    Structural flexibility of robotic manipulators becomes significant and limits the performance of a control system when manipulators are large structures, manipulating on large payloads, and/or operating at high speeds. The question of when a manipulator can be considered rigid or must be considered flexible is studied as a function of manipulator dynamics and task characteristics. Results are interpreted in simple quantitative forms which can be used as design and analysis tools to decide whether or not the manipulator flexibility will be a significant factor for a given task condition. The limitations imposed by the manipulator flexibility on the joint variable feedback control system performance is determined using linear and nonlinear methods. The closed loop eigenstructure behavior of finite dimensional models under joint variable feedback is studied and results are compared with the previously reported results.

  10. High performance high-κ/metal gate complementary metal oxide semiconductor circuit element on flexible silicon

    NASA Astrophysics Data System (ADS)

    Torres Sevilla, G. A.; Almuslem, A. S.; Gumus, A.; Hussain, A. M.; Cruz, M. E.; Hussain, M. M.

    2016-02-01

    Thinned silicon based complementary metal oxide semiconductor (CMOS) electronics can be physically flexible. To overcome challenges of limited thinning and damaging of devices originated from back grinding process, we show sequential reactive ion etching of silicon with the assistance from soft polymeric materials to efficiently achieve thinned (40 μm) and flexible (1.5 cm bending radius) silicon based functional CMOS inverters with high-κ/metal gate transistors. Notable advances through this study shows large area of silicon thinning with pre-fabricated high performance elements with ultra-large-scale-integration density (using 90 nm node technology) and then dicing of such large and thinned (seemingly fragile) pieces into smaller pieces using excimer laser. The impact of various mechanical bending and bending cycles show undeterred high performance of flexible silicon CMOS inverters. Future work will include transfer of diced silicon chips to destination site, interconnects, and packaging to obtain fully flexible electronic systems in CMOS compatible way.

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

    PubMed

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

    2013-03-30

    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

  12. Thermal Insulation Performance of Flexible Piping for Use in HTS Power Cables

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)

    2001-01-01

    High-temperature superconducting (HTS) cables that typically operate at temperatures below 80 K are being developed for power transmission. The practical application of HTS power cables will require the use of flexible piping to contain the cable and the liquid nitrogen coolant. A study of thermal performance of multilayer insulation (MLI) was conducted in geometries representing both rigid and flexible piping. This experimental study performed at the Cryogenics Test Laboratory of NASA Kennedy Space Center provides a framework for the development of cost-effective, efficient thermal insulation systems that will support these long-distance flexible lines containing HTS power cables. The overall thermal performance of the insulation system for a rigid configuration and for a flexible configuration, simulating a flexible HTS power cable, was determined by the steady-state liquid nitrogen boiloff method under the full range of vacuum levels. Two different cylindrically rolled material systems were tested: a standard MLI and a layered composite insulation (LCI). Comparisons of ideal MLI, MLI on rigid piping, and MLI between flexible piping are presented.

  13. Pervious Pavement System Evaluation-Paper

    EPA Science Inventory

    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...

  14. High-performance flexible organic light-emitting diodes using embedded silver network transparent electrodes.

    PubMed

    Zhou, Lei; Xiang, Heng-Yang; Shen, Su; Li, Yan-Qing; Chen, Jing-De; Xie, Hao-Jun; Goldthorpe, Irene A; Chen, Lin-Sen; Lee, Shuit-Tong; Tang, Jian-Xin

    2014-12-23

    Because of their mechanical flexibility, organic light-emitting diodes (OLEDs) hold great promise as a leading technology for display and lighting applications in wearable electronics. The development of flexible OLEDs requires high-quality transparent conductive electrodes with superior bendability and roll-to-roll manufacturing compatibility to replace indium tin oxide (ITO) anodes. Here, we present a flexible transparent conductor on plastic with embedded silver networks which is used to achieve flexible, highly power-efficient large-area green and white OLEDs. By combining an improved outcoupling structure for simultaneously extracting light in waveguide and substrate modes and reducing the surface plasmonic losses, flexible white OLEDs exhibit a power efficiency of 106 lm W(-1) at 1000 cd m(-2) with angular color stability, which is significantly higher than all other reports of flexible white OLEDs. These results represent an exciting step toward the realization of ITO-free, high-efficiency OLEDs for use in a wide variety of high-performance flexible applications. PMID:25470615

  15. Latex improvement of recycled asphalt pavement

    NASA Astrophysics Data System (ADS)

    Drennon, C.

    1982-08-01

    The performance of a single unmodified milled recycled asphalt concrete was compared to milled asphalt concrete modified by addition of three types of rubber latex. Latex was added at 2, 3, 5, and 8 percent latex by weight of asphalt in the asphalt concrete. Lattices used were a styrene butadiene (SBR), a natural rubber (NR), an acrylonitrile butadiene (NBR), and four varieties of out of specification SBR lattices. Marshall tests, while indecisive, showed a modest improvement in properties of SBR and NR added material at 3 and 5 percent latex. Addition of NBR latex caused deterioration in Marshall stability and flow over that of control. Repeated load tests were run using the indirect tensile test, analyzed by the VESYS program, which computes life of pavements. Repeated load tests showed improvement in asphalt concrete life when 3 and 5 percent SBR was added. Improvement was also shown by the out of specification SBR.

  16. A performance comparison of integration algorithms in simulating flexible structures

    NASA Technical Reports Server (NTRS)

    Howe, R. M.

    1989-01-01

    Asymptotic formulas for the characteristic root errors as well as transfer function gain and phase errors are presented for a number of traditional and new integration methods. Normalized stability regions in the lambda h plane are compared for the various methods. In particular, it is shown that a modified form of Euler integration with root matching is an especially efficient method for simulating lightly-damped structural modes. The method has been used successfully for structural bending modes in the real-time simulation of missiles. Performance of this algorithm is compared with other special algorithms, including the state-transition method. A predictor-corrector version of the modified Euler algorithm permits it to be extended to the simulation of nonlinear models of the type likely to be obtained when using the discretized structure approach. Performance of the different integration methods is also compared for integration step sizes larger than those for which the asymptotic formulas are valid. It is concluded that many traditional integration methods, such as RD-4, are not competitive in the simulation of lightly damped structures.

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

    SciTech Connect

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

    2001-11-21

    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.

  18. Reinforcement of asphalt concrete pavement by segments of exhausted fiber used for sorption of oil spill

    NASA Astrophysics Data System (ADS)

    Lukashevich, V. N.; Efanov, I. N.

    2015-01-01

    The paper is aimed at construction of the experimental road pavement made of dispersed reinforced asphalt concrete. Electronic paramagnetic resonance, infrared spectroscopy and fluorescent bitumen studies were used to prove that disperse reinforcement of asphalt concrete mixtures with fibers of exhausted sorbents reduce the selective filtration of low polymeric fractions of petroleum bitumen and improve its properties in the adsorption layer. Sesquioxides are neutralized as catalysts aging asphalt binder. This leads to improvement in the elasticity of bitumen films at low temperatures and provide better crack resistance of coatings to reduce the intensity of the aging of asphalt binder, and, therefore, to increase the durability of road pavements. The experimental road pavement made of dispersed reinforced asphalt concrete operated during 4 years and demonstrated better transport- performance properties in comparison with the analogue pavements.

  19. A test of porous pavement effectiveness on clay soils during natural storm events.

    PubMed

    Dreelin, Erin A; Fowler, Laurie; Ronald Carroll, C

    2006-02-01

    Porous pavements allow precipitation to infiltrate through the pavement to the soil, reducing the volume of stormwater runoff produced at a site. However, porous pavements are not widely used on fine-grained soils due to concerns about their performance. Our objective was to investigate the efficacy of porous pavements in controlling stormwater runoff on clay soils. We compared the performance of an asphalt parking lot and a porous pavement parking lot of grass pavers in Athens, Georgia, USA, over relatively small and low-intensity rain events. The porous lot produced 93% less runoff than the asphalt lot. The total volume of runoff at the porous lot was significantly less than the asphalt lot (t = 2.96, p = 0.009). Turbidity was significantly greater at the asphalt lot (t = 6.18, p < 0.001) whereas conductivity was significantly higher at the porous lot (t = 2.31, p = 0.03). Metal and nutrient concentrations were below detection limits at both lots during seven of nine small storm events. During events in which we could detect pollutants, calcium, zinc, silica, and total phosphorus concentrations were higher at the asphalt lot whereas total nitrogen concentrations were greater at the porous lot. Our results suggest porous pavements are a viable option for reducing stormwater runoff and some pollutants from small storms or the first flush from large storms on clay soils. PMID:16426659

  20. Statistical classification of road pavements using near field vehicle rolling noise measurements.

    PubMed

    Paulo, Joel Preto; Coelho, J L Bento; Figueiredo, Mário A T

    2010-10-01

    Low noise surfaces have been increasingly considered as a viable and cost-effective alternative to acoustical barriers. However, road planners and administrators frequently lack information on the correlation between the type of road surface and the resulting noise emission profile. To address this problem, a method to identify and classify different types of road pavements was developed, whereby near field road noise is analyzed using statistical learning methods. The vehicle rolling sound signal near the tires and close to the road surface was acquired by two microphones in a special arrangement which implements the Close-Proximity method. A set of features, characterizing the properties of the road pavement, was extracted from the corresponding sound profiles. A feature selection method was used to automatically select those that are most relevant in predicting the type of pavement, while reducing the computational cost. A set of different types of road pavement segments were tested and the performance of the classifier was evaluated. Results of pavement classification performed during a road journey are presented on a map, together with geographical data. This procedure leads to a considerable improvement in the quality of road pavement noise data, thereby increasing the accuracy of road traffic noise prediction models. PMID:20968348

  1. An application of smart dust for pavement condition monitoring

    NASA Astrophysics Data System (ADS)

    Ferzli, Nadim A.; Ivey, Richard A.; King, Timothy; Sandburg, Colby J.; Pei, Jin-Song; Zaman, Musharraf M.; Refai, Hazem H.; Lin, Hung, Jr.; Landrum, Aaron; Victor, Rory

    2006-03-01

    Pavement maintenance is vital for travel safety; detecting road weather conditions using a wireless sensing network poses many challenges due to the harsh environment. This paper presents some preliminary results of an ongoing effort of applying "Smart Dust" sensor network for monitoring pavement temperature and moisture condition to detect icy road condition. Careful considerations yield effective solutions to various hardware and software development issues including the selection of sensors and antenna, design of casing, interfacing motes with alien sensors and programming of motes. A series of experiments is carried out to study traffic interference to packet delivery performance of a small-scale sensor network in a pseudo-field environment. In addition, several overnight tests are conducted to study the performance of motes operated under a power efficient condition. The results are analyzed and challenges are identified in this smart sensing application. The aforementioned research activities would benefit robust real-world implementations of off-the-shelf sensor network products.

  2. Solution-processed high-performance colloidal quantum dot tandem photodetectors on flexible substrates

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenyu; You, Guanjun; Wang, Li; Liu, Jie; Hu, Wenjia; Zhang, Yu; Xu, Jian

    2014-08-01

    We report a high-performance colloidal quantum dot (CQD)-based near-infrared tandem photodetector fabricated on flexible substrates via solution-processed method. The tandem photodetector on poly(ethylene terephthalate) substrates exhibited low dark current and high detectivities over ˜8.8 × 1011 Jones at near infrared range at -0.5 V bias and over ˜1013 Jones near 0 bias. The critical bend radii of ˜8 mm and ˜3 mm have been demonstrated for tensile and compressive bending, respectively. The performance of photodetectors remains stable under mechanical stress, making PbSe CQD material a promise candidate for flexible infrared sensing applications.

  3. Effect of flexibility of wing on aerodynamic performance in plunge motion

    NASA Astrophysics Data System (ADS)

    Le, Tuyen Quang; Ko, Jin Hwan; Park, Soo Hyung; Byun, Doyoung

    2009-11-01

    The improvement of aerodynamic performance in plunge motion is investigated through a flexibility of chordwise and spanwise directions by applied a prescribed deformation on a airfoil at Reynolds number of 30000. The aerodynamic performance of flapping motion can be evaluated through a thrust force, a input power and a propulsive efficiency which is a ratio of propulsive power which generate from thrust force to input power. Unsteady viscous flows over NACA 0012 airfoils in plunge motions are computed by using a time-accurate preconditioned Navier-Stokes solver coupled with a volume grid deformation code. For spanwise or chordwise flexibility, there is a optimal phase angle for maximum thrust force and propulsive efficiency. Especially, a combination of spanwise and chordwise flexibility can improve aerodynamic performance higher than that of adding increment from each of flexibility. Compared with rigid motion, 10% deformation in chordwise and spanwise directions with zero phase angle can enhance the thrust force coefficient from 0.22 to 0.38 and 0.54 respectively, while thrust force coefficient is 0.8 by combination of spanwise and chordwise flexibility.

  4. The use of reflective and permeable pavements as a potential practice for heat island mitigation and stormwater management

    NASA Astrophysics Data System (ADS)

    Li, H.; Harvey, J. T.; Holland, T. J.; Kayhanian, M.

    2013-03-01

    To help address the built environmental issues of both heat island and stormwater runoff, strategies that make pavements cooler and permeable have been investigated through measurements and modeling of a set of pavement test sections. The investigation included the hydraulic and thermal performance of the pavements. The permeability results showed that permeable interlocking concrete pavers have the highest permeability (or infiltration rate, ˜0.5 cm s-1). The two permeable asphalt pavements showed the lowest permeability, but still had an infiltration rate of ˜0.1 cm s-1, which is adequate to drain rainwater without generating surface runoff during most typical rain events in central California. An increase in albedo can significantly reduce the daytime high surface temperature in summer. Permeable pavements under wet conditions could give lower surface temperatures than impermeable pavements. The cooling effect highly depends on the availability of moisture near the surface layer and the evaporation rate. The peak cooling effect of watering for the test sections was approximately 15-35 °C on the pavement surface temperature in the early afternoon during summer in central California. The evaporative cooling effect on the pavement surface temperature at 4:00 pm on the third day (25 h after watering) was still 2-7 °C lower compared to that on the second day, without considering the higher air temperature on the third day. A separate and related simulation study performed by UCPRC showed that full depth permeable pavements, if designed properly, can carry both light-duty traffic and certain heavy-duty vehicles while retaining the runoff volume captured from an average California storm event. These preliminarily results indicated the technical feasibility of combined reflective and permeable pavements for addressing the built environment issues related to both heat island mitigation and stormwater runoff management.

  5. Use of scrap rubber in asphalt pavement surfaces

    NASA Astrophysics Data System (ADS)

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

    1991-12-01

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

  6. Effective flow resistivity of highway pavements.

    PubMed

    Rochat, Judith L; Read, David R

    2013-12-01

    In the case of highway traffic noise, propagating sound is influenced by the ground over which it travels, whether it is the pavement itself or the ground between the highway and nearby communities. Properly accounting for ground type in modeling can increase accuracy in noise impact determinations and noise abatement design. Pavement-specific effective flow resistivity values are being investigated for inclusion in the Federal Highway Administration Traffic Noise Model, which uses these values in the sound propagation algorithms and currently applies a single effective flow resistivity value to all pavement. Pavement-specific effective flow resistivity values were obtained by applying a modified version of the American National Standards Institute S1.18 standard. The data analysis process was tailored to allow for increased sensitivity and extraction of effective flow resistivity values for a broad range of pavements (sound absorptive to reflective). For porous pavements (sound absorptive), it was determined that examination of the measured data can reveal influence from an underlying structure. Use of such techniques can aid in the design of quieter pavements. PMID:25669283

  7. Significantly enhanced robustness and electrochemical performance of flexible carbon nanotube-based supercapacitors by electrodepositing polypyrrole

    NASA Astrophysics Data System (ADS)

    Chen, Yanli; Du, Lianhuan; Yang, Peihua; Sun, Peng; Yu, Xiang; Mai, Wenjie

    2015-08-01

    Here, we report robust, flexible CNT-based supercapacitor (SC) electrodes fabricated by electrodepositing polypyrrole (PPy) on freestanding vacuum-filtered CNT film. These electrodes demonstrate significantly improved mechanical properties (with the ultimate tensile strength of 16 MPa), and greatly enhanced electrochemical performance (5.6 times larger areal capacitance). The major drawback of conductive polymer electrodes is the fast capacitance decay caused by structural breakdown, which decreases cycling stability but this is not observed in our case. All-solid-state SCs assembled with the robust CNT/PPy electrodes exhibit excellent flexibility, long lifetime (95% capacitance retention after 10,000 cycles) and high electrochemical performance (a total device volumetric capacitance of 4.9 F/cm3). Moreover, a flexible SC pack is demonstrated to light up 53 LEDs or drive a digital watch, indicating the broad potential application of our SCs for portable/wearable electronics.

  8. Asphalt pavement aging and temperature dependent properties using functionally graded viscoelastic model

    NASA Astrophysics Data System (ADS)

    Dave, Eshan V.

    Asphalt concrete pavements are inherently graded viscoelastic structures. Oxidative aging of asphalt binder and temperature cycling due to climatic conditions being the major cause of non-homogeneity. Current pavement analysis and simulation procedures dwell on the use of layered approach to account for these non-homogeneities. The conventional finite-element modeling (FEM) technique discretizes the problem domain into smaller elements, each with a unique constitutive property. However the assignment of unique material property description to an element in the FEM approach makes it an unattractive choice for simulation of problems with material non-homogeneities. Specialized elements such as "graded elements" allow for non-homogenous material property definitions within an element. This dissertation describes the development of graded viscoelastic finite element analysis method and its application for analysis of asphalt concrete pavements. Results show that the present research improves efficiency and accuracy of simulations for asphalt pavement systems. Some of the practical implications of this work include the new technique's capability for accurate analysis and design of asphalt pavements and overlay systems and for the determination of pavement performance with varying climatic conditions and amount of in-service age. Other application areas include simulation of functionally graded fiber-reinforced concrete, geotechnical materials, metal and metal composites at high temperatures, polymers, and several other naturally existing and engineered materials.

  9. Greenhouse gas emissions of alternative pavement designs: framework development and illustrative application.

    PubMed

    Liu, Xiaoyu; Cui, Qingbin; Schwartz, Charles

    2014-01-01

    Pavement rehabilitation is carbon intensive and the choice of pavement type is a critical factor in controlling greenhouse gas (GHG) emissions. The existing body of knowledge is not able to support decision-making on pavement choice due to a lack of consensus on the system boundaries, the functional units and the estimation periods. Excessive data requirements further inhibit the generalization of the existing methodologies for design evaluation at the early planning stage. This study proposes a practical life-cycle GHG estimation approach, which is arguably effective to benchmark pavement emissions given project bid tabulation. A set of case studies conducted for this study suggest that recycled asphalt pavement (e.g., foam stabilized base (FSB), and warm mix asphalt (WMA)) would prevent up to 50% of GHGs from the initial construction phase. However, from a life-cycle perspective, pavement emissions are dictated largely by the traffic characteristics and the analysis period for the use phase. The benefits from using recycled materials (e.g., FSB) are likely to diminish if the recycled products do not perform as well as those properly proportioned with less recycled materials, or if the recycled materials are locally unavailable. When the AADT reaches 10,000, use phase releases more than 97% of the life cycle emissions and the emissions difference among alternative designs will be within 1%. PMID:24333742

  10. Assessment of highway pavements using GPR

    NASA Astrophysics Data System (ADS)

    Plati, Christina; Loizos, Andreas

    2015-04-01

    Highway infrastructure is a prerequisite for a functioning economy and social life. Highways, often prone to congestion and disruption, are one of the aspects of a modern transport network that require maximum efficiency if an integrated transport network, and sustainable mobility, is to be achieved. Assessing the condition of highway structures, to plan subsequent maintenance, is essential to allow the long-term functioning of a road network. Optimizing the methods used for such assessment will lead to better information being obtained about the road and underlying ground conditions. The condition of highway structures will be affected by a number of factors, including the properties of the highway pavement, the supporting sub-base and the subgrade (natural ground), and the ability to obtain good information about the entire road structure, from pavement to subgrade, allows appropriate maintenance programs to be planned. The maintenance of highway pavements causes considerable cost and in many cases obstruction to traffic flow. In this situation, methods that provide information on the present condition of pavement structure non-destructively and economically are of great interest. It has been shown that Ground-Penetrating-Radar (GPR), which is a Non Destructive Technique (NDT), can deliver information that is useful for the planning of pavement maintenance activities. More specifically GPR is used by pavement engineers in order to determine physical properties and characteristics of the pavement structure, information that is valuable for the assessment of pavement condition. This work gives an overview on the practical application of GPR using examples from highway asphalt pavements monitoring. The presented individual applications of GPR pavement diagnostics concern structure homogeneity, thickness of pavement layers, dielectric properties of asphalt materials etc. It is worthwhile mentioning that a number of applications are standard procedures, either separately or in combination with other NDT methods, but even for them there is still a room for improvement and there is still need to set stricter regulations Comparisons between radar results and ground truth data produce evidence in support of the statement that the accuracy and reliability of radar results is sufficient for facing many issues related to the evaluation of asphalt pavements. Thus, benefits and limits of this method are shown and recommendations for GPR inspections are presented. Acknowledgments: This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

  11. AN OPTIMAL MAINTENANCE MANAGEMENT MODEL FOR AIRPORT CONCRETE PAVEMENT

    NASA Astrophysics Data System (ADS)

    Shimomura, Taizo; Fujimori, Yuji; Kaito, Kiyoyuki; Obama, Kengo; Kobayashi, Kiyoshi

    In this paper, an optimal management model is formulated for the performance-based rehabilitation/maintenance contract for airport concrete pavement, whereby two types of life cycle cost risks, i.e., ground consolidation risk and concrete depreciation risk, are explicitly considered. The non-homogenous Markov chain model is formulated to represent the deterioration processes of concrete pavement which are conditional upon the ground consolidation processes. The optimal non-homogenous Markov decision model with multiple types of risk is presented to design the optimal rehabilitation/maintenance plans. And the methodology to revise the optimal rehabilitation/maintenance plans based upon the monitoring data by the Bayesian up-to-dating rules. The validity of the methodology presented in this paper is examined based upon the case studies carried out for the H airport.

  12. Full scale demonstration of air-purifying pavement.

    PubMed

    Ballari, M M; Brouwers, H J H

    2013-06-15

    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. PMID:23731840

  13. Towards a new generation of mission planning systems: Flexibility and performance

    NASA Technical Reports Server (NTRS)

    Gasquet, A.; Parrod, Y.; Desaintvincent, A.

    1994-01-01

    This paper presents some new approaches which are required for a better adequacy of Mission Planning Systems. In particular, the performance flexibility and genericity issues are discussed based on experience acquired through various Mission Planning systems developed by Matra Marconi Space.

  14. The Ability of Psychological Flexibility and Job Control to Predict Learning, Job Performance, and Mental Health

    ERIC Educational Resources Information Center

    Bond, Frank W.; Flaxman, Paul E.

    2006-01-01

    This longitudinal study tested the degree to which an individual characteristic, psychological flexibility, and a work organization variable, job control, predicted ability to learn new skills at work, job performance, and mental health, amongst call center workers in the United Kingdom (N = 448). As hypothesized, results indicated that job

  15. The Ability of Psychological Flexibility and Job Control to Predict Learning, Job Performance, and Mental Health

    ERIC Educational Resources Information Center

    Bond, Frank W.; Flaxman, Paul E.

    2006-01-01

    This longitudinal study tested the degree to which an individual characteristic, psychological flexibility, and a work organization variable, job control, predicted ability to learn new skills at work, job performance, and mental health, amongst call center workers in the United Kingdom (N = 448). As hypothesized, results indicated that job…

  16. The Effects of Cognitive Flexibility and Openness to Change on College Students' Academic Performance

    ERIC Educational Resources Information Center

    Lin, Ya-Wei

    2013-01-01

    This research investigated the relationship between cognitive flexibility and openness to change and their effects on academic performance among college students at National Taiwan University in Taipei, Taiwan. Using a quantitative purposeful sampling strategy, data were collected in classroom settings from 770 undergraduate voluntary…

  17. Recycling asphalt pavements. January 1975-January 1990 (a Bibliography from the COMPENDEX data base). Report for January 1975-January 1990

    SciTech Connect

    Not Available

    1990-03-01

    This bibliography contains citations concerning the recycling of asphalt-containing pavement materials. Articles include examples of recycling asphalt pavements; performance testing of recycled paving; methods including cold in-place, cold off-site, and hot-mix recycling; additives in recycled pavement for better performance; use of scrap roofing asphalt in conjunction with recycled paving; economics of recycling; process design; and process variables. Recycling of other materials is considered in related bibliographies. (Contains 130 citations fully indexed and including a title list.)

  18. Pervious Pavement System Evaluation- Abstract 1

    EPA Science Inventory

    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...

  19. The Edison Environmental Center Permeable Pavement Site

    EPA Science Inventory

    This a presentation for a Community Outreach Event called "Chemistry Works and Celebration of International Year of Chemistry." It will review the permeable pavement research project at the Edison Environmental center.

  20. Permeable Pavement Research - Edison, New Jersey

    EPA Science Inventory

    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. ...

  1. Flexible conducting polymer/reduced graphene oxide films: synthesis, characterization, and electrochemical performance

    NASA Astrophysics Data System (ADS)

    Yang, Wenyao; Zhao, Yuetao; He, Xin; Chen, Yan; Xu, Jianhua; Li, Shibin; Yang, Yajie; Jiang, Yadong

    2015-05-01

    In this paper, we demonstrate the preparation of a flexible poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonate)/reduced graphene oxide (PEDOT-PSS/RGO) film with a layered structure via a simple vacuum filtered method as a high performance electrochemical electrode. The PEDOT-PSS/RGO films are characterized by scanning electron microscopy (SEM), X-ray diffraction, Raman spectroscopy, and Fourier transform infrared (FT-IR) spectrometry. The results indicate that a layer-ordered structure is constructed in this nanocomposite during the vacuum filtering process. The electrochemical performances of the flexible films are characterized by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge. The results reveal that a 193.7 F/g highly specific capacitance of nanocomposite film is achieved at a current density of 500 mA/g. This flexible and self-supporting nanocomposite film exhibits excellent cycling stability, and the capacity retention is 90.6 % after 1000 cycles, which shows promising application as high-performance electrode materials for flexible energy-storage devices.

  2. Fusing complementary images for pavement cracking measurements

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  3. Reducing traffic noise with quieter pavements

    NASA Astrophysics Data System (ADS)

    Donavan, Paul

    2005-09-01

    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.

  4. Path planning for machine vision assisted, teleoperated pavement crack sealer

    SciTech Connect

    Kim, Y.S.; Haas, C.T.; Greer, R.

    1998-03-01

    During the last few years, several teleoperated and machine-vision-assisted systems have been developed in construction and maintenance areas such as pavement crack sealing, sewer pipe rehabilitation, excavation, surface finishing, and materials handling. This paper presents a path-planning algorithm used for a machine-vision-assisted automatic pavement crack sealing system. In general, path planning is an important task for optimal motion of a robot whether its environment is structured or unstructured. Manual path planning is not always possible or desirable. A simple greedy path algorithm is utilized for optimal motion of the automated pavement crack sealer. Some unique and broadly applicable computational tools and data structures are required to implement the algorithm in a digital image domain. These components are described, then the performance of the algorithm is compared with the implicit manual path plans of system operators. The comparison is based on computational cost versus overall gains in crack-sealing-process efficiency. Applications of this work in teleoperation, graphical control, and other infrastructure maintenance areas are also suggested.

  5. Thermal Stability Analysis under Embankment with Asphalt Pavement and Cement Pavement in Permafrost Regions

    PubMed Central

    Jinping, Li; Xiaojuan, Quan

    2013-01-01

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

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

    PubMed

    Junwei, Zhang; Jinping, Li; Xiaojuan, Quan

    2013-01-01

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

  7. Metallic Fabrics as the Current Collector for High-Performance Graphene-Based Flexible Solid-State Supercapacitor.

    PubMed

    Yu, Jianhui; Wu, Jifeng; Wang, Haozong; Zhou, Anan; Huang, Chaoqiang; Bai, Hua; Li, Lei

    2016-02-24

    Flexible solid-state supercapacitors attract more and more attention as the power supply for wearable electronics. To fabricate such devices, the flexible and economical current collectors are needed. In this paper, we report the stainless steel fabrics as the current collector for high-performance graphene-based supercapacitors. The stainless steel fabrics have superior properties compared with the widely used flexible current collectors. The flexible supercapacitors show large specific capacitance of 180.4 mF/cm(2), and capacitance retention of 96.8% after 7500 charge-discharge cycles. Furthermore, 96.4% of the capacitance is retained after 800 repeating stretching-bending cycles. The high performance is related to the excellent conductivity, good mechanical flexibility, and high electrochemical stability of the stainless steel fabrics. The achievement of such high-performance and flexible supercapacitor can open up exciting opportunities for wearable electronics and energy storage applications. PMID:26830192

  8. Aerodynamic performance of a hovering hawkmoth with flexible wings: a computational approach

    PubMed Central

    Nakata, Toshiyuki; Liu, Hao

    2012-01-01

    Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction based analysis on the aerodynamic performance of a hovering hawkmoth, Manduca, with an integrated computational model of a hovering insect with rigid and flexible wings. Aerodynamic performance of flapping wings with passive deformation or prescribed deformation is evaluated in terms of aerodynamic force, power and efficiency. Our results reveal that wing flexibility can increase downwash in wake and hence aerodynamic force: first, a dynamic wing bending is observed, which delays the breakdown of leading edge vortex near the wing tip, responsible for augmenting the aerodynamic force-production; second, a combination of the dynamic change of wing bending and twist favourably modifies the wing kinematics in the distal area, which leads to the aerodynamic force enhancement immediately before stroke reversal. Moreover, an increase in hovering efficiency of the flexible wing is achieved as a result of the wing twist. An extensive study of wing stiffness effect on aerodynamic performance is further conducted through a tuning of Young's modulus and thickness, indicating that insect wing structures may be optimized not only in terms of aerodynamic performance but also dependent on many factors, such as the wing strength, the circulation capability of wing veins and the control of wing movements. PMID:21831896

  9. Aerodynamic performance of a hovering hawkmoth with flexible wings: a computational approach.

    PubMed

    Nakata, Toshiyuki; Liu, Hao

    2012-02-22

    Insect wings are deformable structures that change shape passively and dynamically owing to inertial and aerodynamic forces during flight. It is still unclear how the three-dimensional and passive change of wing kinematics owing to inherent wing flexibility contributes to unsteady aerodynamics and energetics in insect flapping flight. Here, we perform a systematic fluid-structure interaction based analysis on the aerodynamic performance of a hovering hawkmoth, Manduca, with an integrated computational model of a hovering insect with rigid and flexible wings. Aerodynamic performance of flapping wings with passive deformation or prescribed deformation is evaluated in terms of aerodynamic force, power and efficiency. Our results reveal that wing flexibility can increase downwash in wake and hence aerodynamic force: first, a dynamic wing bending is observed, which delays the breakdown of leading edge vortex near the wing tip, responsible for augmenting the aerodynamic force-production; second, a combination of the dynamic change of wing bending and twist favourably modifies the wing kinematics in the distal area, which leads to the aerodynamic force enhancement immediately before stroke reversal. Moreover, an increase in hovering efficiency of the flexible wing is achieved as a result of the wing twist. An extensive study of wing stiffness effect on aerodynamic performance is further conducted through a tuning of Young's modulus and thickness, indicating that insect wing structures may be optimized not only in terms of aerodynamic performance but also dependent on many factors, such as the wing strength, the circulation capability of wing veins and the control of wing movements. PMID:21831896

  10. Guidelines and specifications for the use of reclaimed aggregates in pavement. Final report

    SciTech Connect

    Chini, S.A.; Kuo, S.S.; Duxbury, J.P.; Monteiro, F.M.B.R.; Mbwambo, W.J.

    1998-08-01

    The project focused on evaluating the performance of recycled concrete for use as a base material under hot mix asphalt pavements and as an aggregate in Portland cement concrete pavements. In order to meet this objective, several goals were established. First, published literature on RCA was reviewed and a survey of State Highway Agencies (SHA) was performed to determine the extent of use of RCA in highway projects. Second, the RCA was tested at the FDOT Material Lab in Gainesville, Florida, to determine the material properties. Third, by using the output from the falling weight deflectometer test along with the KENSLABS and KENLAYER computer programs (Huang, 1993), a theoretical analysis was performed to predict the number of repetitions before the pavements failed in both the fatigue and permanent deformation criteria. Lastly, nine design sections involving HMA and PCC pavements were constructed at the University of Central Florida`s Circular Accelerated Test Track (UCF-CATT) to evaluate the response of the pavement sections made with RCA under actual dual-wheel loading.

  11. How does emotion influence different creative performances? The mediating role of cognitive flexibility.

    PubMed

    Lin, Wei-Lun; Tsai, Ping-Hsun; Lin, Hung-Yu; Chen, Hsueh-Chih

    2014-01-01

    Cognitive flexibility is proposed to be one of the factors underlying how positive emotions can improve creativity. However, previous works have seldom set up or empirically measured an independent index to demonstrate its mediating effect, nor have they investigated its mediating role on different types of creative performances, which involve distinct processes. In this study, 120 participants were randomly assigned to positive, neutral or negative affect conditions. Their levels of cognitive flexibility were then measured by a switch task. Finally, their creative performances were calibrated by either an open-ended divergent thinking test or a closed-ended insight problem-solving task. The results showed that positive emotional states could reduce switch costs and enhance both types of creative performances. However, cognitive flexibility exhibited a full mediating effect only on the relationship between positive emotion and insight problem solving, but not between positive emotion and divergent thinking. Divergent thinking was instead more associated with arousal level. These results suggest that emotions might influence different creative performances through distinct mechanisms. PMID:24237485

  12. Solution-processed high-performance colloidal quantum dot tandem photodetectors on flexible substrates

    SciTech Connect

    Jiang, Zhenyu; You, Guanjun; Wang, Li; Liu, Jie; Xu, Jian; Hu, Wenjia; Zhang, Yu

    2014-08-28

    We report a high-performance colloidal quantum dot (CQD)-based near-infrared tandem photodetector fabricated on flexible substrates via solution-processed method. The tandem photodetector on poly(ethylene terephthalate) substrates exhibited low dark current and high detectivities over ∼8.8 × 10{sup 11} Jones at near infrared range at −0.5 V bias and over ∼10{sup 13} Jones near 0 bias. The critical bend radii of ∼8 mm and ∼3 mm have been demonstrated for tensile and compressive bending, respectively. The performance of photodetectors remains stable under mechanical stress, making PbSe CQD material a promise candidate for flexible infrared sensing applications.

  13. Effect of Back Contact and Rapid Thermal Processing Conditions on Flexible CdTe Device Performance

    SciTech Connect

    Mahabaduge, Hasitha; Meysing, D. M.; Rance, Will L.; Burst, James M.; Reese, Matthew O.; Wolden, C. A.; Gessert, Timothy A.; Metzger, Wyatt K.; Garner, S.; Barnes, Teresa M.

    2015-06-14

    Flexible CdTe solar cells on ultra-thin glass substrates can enable new applications that require high specific power, unique form-factors, and low manufacturing costs. To be successful, these cells must be cost competitive, have high efficiency, and have high reliability. Here we present back contact processing conditions that enabled us to achieve over 16% efficiency on flexible Corning (R) Willow (R) Glass substrates. We used co-evaporated ZnTe:Cu and Au as our back contact and used rapid thermal processing (RTP) to activate the back contact. Both the ZnTe to Cu ratio and the RTP activation temperature provide independent control over the device performance. We have investigated the influence of various RTP conditions to Cu activation and distribution. Current density-voltage, capacitance-voltage measurements along with device simulations were used to examine the device performance in terms of ZnTe to Cu ratio and rapid thermal activation temperature.

  14. High-performance flexible thin-film transistors exfoliated from bulk wafer.

    PubMed

    Zhai, Yujia; Mathew, Leo; Rao, Rajesh; Xu, Dewei; Banerjee, Sanjay K

    2012-11-14

    Mechanically flexible integrated circuits (ICs) have gained increasing attention in recent years with emerging markets in portable electronics. Although a number of thin-film-transistor (TFT) IC solutions have been reported, challenges still remain for the fabrication of inexpensive, high-performance flexible devices. We report a simple and straightforward solution: mechanically exfoliating a thin Si film containing ICs. Transistors and circuits can be prefabricated on bulk silicon wafer with the conventional complementary metal-oxide-semiconductor (CMOS) process flow without additional temperature or process limitations. The short channel MOSFETs exhibit similar electrical performance before and after exfoliation. This exfoliation process also provides a fast and economical approach to producing thinned silicon wafers, which is a key enabler for three-dimensional (3D) silicon integration based on Through Silicon Vias (TSVs). PMID:23092185

  15. Study of the durability of demolition aggregates on pavements

    NASA Astrophysics Data System (ADS)

    Bachir, Melbouci; Fazia, Boudjemia

    2009-06-01

    This work is an experimental contribution to the study of durability of various materials coming from the demolition of buildings for their use in the flexible infrastructures of pavements. However, these pavements undergo traffic loading which causes, in the long time permanent deformations and settlements thus generating significant degradations of materials. Various recent works aim at characterizing these materials. This work falls under this scope and gives an approach of the mechanical behavior and the response of these last to repetitive loadings. After identification of materials and the determination of the characteristics of hardness and durability, we studied their mechanical behavior with cyclic shearing on these three materials (aggregates of concrete, brick and concrete block). These tests enabled us to analyze the mechanisms which occur through the various parameters related to loading (the amplitude and the repetition of loading, the parameters related to materials (the water content, the density and the grain size distribution). The study of the durability of these materials consists on quantifying the degradation rate of the grains after the various tests and the grain size distribution which governs the amplitude of crushing.

  16. A flexible and inexpensive high-performance auditory evoked response recording system appropriate for research purposes.

    PubMed

    Valderrama, Joaquin T; de la Torre, Angel; Alvarez, Isaac; Segura, Jose Carlos; Sainz, Manuel; Vargas, Jose Luis

    2014-10-01

    Recording auditory evoked responses (AER) is done not only in hospitals and clinics worldwide to detect hearing impairments and estimate hearing thresholds, but also in research centers to understand and model the mechanisms involved in the process of hearing. This paper describes a high-performance, flexible, and inexpensive AER recording system. A full description of the hardware and software modules that compose the AER recording system is provided. The performance of this system was evaluated by conducting five experiments with both real and artificially synthesized auditory brainstem response and middle latency response signals at different intensity levels and stimulation rates. The results indicate that the flexibility of the described system is appropriate to record AER signals under several recording conditions. The AER recording system described in this article is a flexible and inexpensive high-performance AER recording system. This recording system also incorporates a platform through which users are allowed to implement advanced signal processing methods. Moreover, its manufacturing cost is significantly lower than that of other commercially available alternatives. These advantages may prove useful in many research applications in audiology. PMID:24870606

  17. POROUS PAVEMENT. PHASE I. DESIGN AND OPERATIONAL CRITERIA

    EPA Science Inventory

    Design and operational criteria, utilization concepts, benefits and disadvantages, as well as other characteristics of porous pavements are presented in this report. Particular emphasis is placed on porous asphalt pavements, but the criteria and design approach are applicable to ...

  18. Spills on Flat Inclined Pavements

    SciTech Connect

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

    2004-03-01

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

  19. High Performance, Robust Control of Flexible Space Structures: MSFC Center Director's Discretionary Fund

    NASA Technical Reports Server (NTRS)

    Whorton, M. S.

    1998-01-01

    Many spacecraft systems have ambitious objectives that place stringent requirements on control systems. Achievable performance is often limited because of difficulty of obtaining accurate models for flexible space structures. To achieve sufficiently high performance to accomplish mission objectives may require the ability to refine the control design model based on closed-loop test data and tune the controller based on the refined model. A control system design procedure is developed based on mixed H2/H(infinity) optimization to synthesize a set of controllers explicitly trading between nominal performance and robust stability. A homotopy algorithm is presented which generates a trajectory of gains that may be implemented to determine maximum achievable performance for a given model error bound. Examples show that a better balance between robustness and performance is obtained using the mixed H2/H(infinity) design method than either H2 or mu-synthesis control design. A second contribution is a new procedure for closed-loop system identification which refines parameters of a control design model in a canonical realization. Examples demonstrate convergence of the parameter estimation and improved performance realized by using the refined model for controller redesign. These developments result in an effective mechanism for achieving high-performance control of flexible space structures.

  20. Aligned Single-Crystalline Perovskite Microwire Arrays for High-Performance Flexible Image Sensors with Long-Term Stability.

    PubMed

    Deng, Wei; Zhang, Xiujuan; Huang, Liming; Xu, Xiuzhen; Wang, Liang; Wang, Jincheng; Shang, Qixun; Lee, Shuit-Tong; Jie, Jiansheng

    2016-03-01

    A simple, low-cost blade-coating method is developed for the large-area fabrication of single-crystalline aligned CH3 NH3 PbI3 microwire (MW) arrays. The solution-coating method is applicable to flexible substrates, enabling the fabrication of MW-array-based photodetectors with excellent long-term stability, flexibility, and bending durability. Integrated devices from such photodetectors demonstrate high performance for high-resolution, flexible image sensors. PMID:26780594

  1. Pavement Sealcoat, PAHs, and the Environment

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  2. Vacancy associates-rich ultrathin nanosheets for high performance and flexible nonvolatile memory device.

    PubMed

    Liang, Lin; Li, Kun; Xiao, Chong; Fan, Shaojuan; Liu, Jiao; Zhang, Wenshuai; Xu, Wenhui; Tong, Wei; Liao, Jiaying; Zhou, Yingying; Ye, Bangjiao; Xie, Yi

    2015-03-01

    On the road of innovation in modern information technology, resistive switching random access memory (RRAM) has been considered to be the best potential candidate to replace the conventional Si-based technologies. In fact, the key prerequisite of high storage density and low power consumption as well as flexibility for the tangible next generation of nonvolatile memories has stimulated extensive research into RRAM. Herein, we highlight an inorganic graphene analogue, ultrathin WO3·H2O nanosheets with only 2-3 nm thickness, as a promising material to construct a high performance and flexible RRAM device. The abundant vacancy associates in the ultrathin nanosheets, revealed by the positron annihilation spectra, act not only carrier reservoir to provide carriers but also capture center to trap the actived Cu(2+) for the formation of conductive filaments, which synergistically realize the resistive switching memory with low operating voltage (+1.0 V/-1.14 V) and large resistance ON/OFF ratio (>10(5)). This ultrathin-nanosheets-based RRAM device also shows long retention time (>10(5) s), good endurance (>5000 cycles), and excellent flexibility. The finding of the existence of distinct defects in ultrathin nanosheets undoubtedly leads to an atomic level deep understanding of the underlying nature of the resistive switching behavior, which may serve as a guide to improve the performances and promote the rapid development of RRAM. PMID:25668153

  3. Effects of acute lipid overload on skeletal muscle insulin resistance, metabolic flexibility, and mitochondrial performance.

    PubMed

    Dubé, John J; Coen, Paul M; DiStefano, Giovanna; Chacon, Alexander C; Helbling, Nicole L; Desimone, Marisa E; Stafanovic-Racic, Maja; Hames, Kazanna C; Despines, Alex A; Toledo, Frederico G S; Goodpaster, Bret H

    2014-12-15

    We hypothesized that acute lipid-induced insulin resistance would be attenuated in high-oxidative muscle of lean trained (LT) endurance athletes due to their enhanced metabolic flexibility and mitochondrial capacity. Lean sedentary (LS), obese sedentary (OS), and LT participants completed two hyperinsulinemic euglycemic clamp studies with and without (glycerol control) the coinfusion of Intralipid. Metabolic flexibility was measured by indirect calorimetry as the oxidation of fatty acids and glucose during fasted and insulin-stimulated conditions, the latter with and without lipid oversupply. Muscle biopsies were obtained for mitochondrial and insulin-signaling studies. During hyperinsulinemia without lipid, glucose infusion rate (GIR) was lowest in OS due to lower rates of nonoxidative glucose disposal (NOGD), whereas state 4 respiration was increased in all groups. Lipid infusion reduced GIR similarly in all subjects and reduced state 4 respiration. However, in LT subjects, fat oxidation was higher with lipid oversupply, and although glucose oxidation was reduced, NOGD was better preserved compared with LS and OS subjects. Mitochondrial performance was positively associated with better NOGD and insulin sensitivity in both conditions. We conclude that enhanced mitochondrial performance with exercise is related to better metabolic flexibility and insulin sensitivity in response to lipid overload. PMID:25352435

  4. Flexible thick-film glucose biosensor: influence of mechanical bending on the performance.

    PubMed

    Chuang, Min-Chieh; Yang, Yang-Li; Tseng, Ta-Feng; Chou, Tzuyang; Lou, Shyh-Liang; Wang, Joseph

    2010-04-15

    The influence of the bending-induced mechanical stress of flexible Nafion/GOx/carbon screen-printed electrodes (SPEs) upon the performance of such glucose biosensors has been examined. Surprisingly, such flexible enzyme/polymer-SPEs operate well following a severe bending-induced mechanical stress (including a 180 degrees pinch), and actually display a substantial sensitivity enhancement following their mechanical bending. The bending-induced sensitivity enhancement is observed only for the amperometric detection of the glucose substrate but not for measurements of hydrogen peroxide, catechol or ferrocyanide at coated or bare SPEs. These (and additional) data indicate that the bending effect is associated primarily with changes in the biocatalytic activity. Such sensitivity enhancement is more pronounced at elevated glucose levels, reflecting the bending-induced changes in the biocatalytic reaction. Factors affecting the bending-induced changes in the performance are examined. While our data clearly indicate that flexible enzyme/polymer-SPEs can tolerate a severe mechanical stress and hold promise as wearable glucose biosensors, delivering the sample to the active sensor surface remains the major challenge for such continuous health monitoring. PMID:20188880

  5. Exact performance analytical model for spectrum allocation in flexible grid optical networks

    NASA Astrophysics Data System (ADS)

    Yu, Yiming; Zhang, Jie; Zhao, Yongli; Li, Hui; Ji, Yuefeng; Gu, Wanyi

    2014-03-01

    Dynamic flexible grid optical networks have gained much attention because of the advantages of high spectrum efficiency and flexibility, while the performance analysis will be more complex compared with fixed grid optical networks. An analytical Markov model is first presented in the paper, which can exactly describe the stochastic characteristics of the spectrum allocation in flexible grid optical networks considering both random-fit and first-fit resource assignment policies. We focus on the effect of spectrum contiguous constraint which has not been systematically studied in respect of mathematical modeling, and three major properties of the model are presented and analyzed. The model can expose key performance features and act as the foundation of modeling the Routing and Spectrum Assignment (RSA) problem with diverse topologies. Two heuristic algorithms are also proposed to make it more tractable. Finally, several key parameters, such as blocking probability, resource utilization rate and fragmentation rate are presented and computed, and the corresponding Monte Carlo simulation results match closely with analytical results, which prove the correctness of this mathematical model.

  6. Hydrodynamic analysis, performance assessment, and actuator design of a flexible tail propulsor in an artificial alligator

    NASA Astrophysics Data System (ADS)

    Philen, Michael; Neu, Wayne

    2011-09-01

    The overall objective of this research is to develop analysis tools for determining actuator requirements and assessing viable actuator technology for design of a flexible tail propulsor in an artificial alligator. A simple hydrodynamic model that includes both reactive and resistive forces along the tail is proposed and the calculated mean thrust agrees well with conventional estimates of drag. Using the hydrodynamic model forces as an input, studies are performed for an alligator ranging in size from 1 cm to 2 m at swimming speeds of 0.3-1.8 body lengths per second containing five antagonistic pairs of actuators distributed along the length of the tail. Several smart materials are considered for the actuation system, and preliminary analysis results indicate that the acrylic electroactive polymer and the flexible matrix composite actuators are potential artificial muscle technologies for the system.

  7. Design and performance of an ultra-flexible two-photon microscope for in vivo research

    PubMed Central

    Mayrhofer, Johannes M.; Haiss, Florent; Haenni, Dominik; Weber, Stefan; Zuend, Marc; Barrett, Matthew J. P.; Ferrari, Kim David; Maechler, Philipp; Saab, Aiman S.; Stobart, Jillian L.; Wyss, Matthias T.; Johannssen, Helge; Osswald, Harald; Palmer, Lucy M.; Revol, Vincent; Schuh, Claus-Dieter; Urban, Claus; Hall, Andrew; Larkum, Matthew E.; Rutz-Innerhofer, Edith; Zeilhofer, Hanns Ulrich; Ziegler, Urs; Weber, Bruno

    2015-01-01

    We present a cost-effective in vivo two-photon microscope with a highly flexible frontend for in vivo research. Our design ensures fast and reproducible access to the area of interest, including rotation of imaging plane, and maximizes space for auxiliary experimental equipment in the vicinity of the animal. Mechanical flexibility is achieved with large motorized linear stages that move the objective in the X, Y, and Z directions up to 130 mm. 360° rotation of the frontend (rotational freedom for one axis) is achieved with the combination of a motorized high precision bearing and gearing. Additionally, the modular design of the frontend, based on commercially available optomechanical parts, allows straightforward updates to future scanning technologies. The design exceeds the mobility of previous movable microscope designs while maintaining high optical performance. PMID:26600989

  8. Investigation of antenna frequency impact on assessing voids of asphalt pavements using GPR

    NASA Astrophysics Data System (ADS)

    Plati, C.; Georgouli, K.; Loizos, A.

    2012-04-01

    Ground Penetrating Radar (GPR) is a Non Destructive Testing (NDT) technique that has been developed and improved upon over the past 30 years. The technique is frequently utilized in order to evaluate and assess pavement structures. GPR, for pavement evaluation purposes, can be described as a remote sensing system that emits a short pulse, of electromagnetic energy, into the pavement, with a central frequency varying from 10 MHz up to 2.5GHz. The two most commonly utilized setups are air-coupled and ground-coupled antenna systems. For air-coupled systems, the antennas are suspended above the pavement surface and can operate at normal traffic speeds (up to ~ 80 Km/h). The major drawback of the air-coupled antenna is that penetration depth is limited. On the other hand, for ground-coupled systems the antennas are in direct contact with the pavement surface, providing for better signal penetration into the pavement structure; however ground coupled systems can achieve only limited operational speeds. As a generalized rule, increasing the GPR central operating frequency, increases the investigation resolution, while decreasing the overall depth of investigation In the light of the above, air-coupled systems have become increasingly popular for the evaluation of the part of the pavement structure, especially for the asphalt layers, while ground-coupled systems are utilized mostly in order to gather information from the entire pavement structure (up to ~ 3 m depth). The majority of GPR pavement studies are carried out with air-coupled horn antennas, as they can be implemented at driving speeds without need for road closures. For instance, the 1 GHz air-coupled horn antenna is commonly used for the estimation of pavement layer thickness. However signals generated by horn antenna systems must have sufficient quality to allow the performance of automated signal processing and qualitative data analysis, especially when pavement data more sensitive to the analysis parameters, such voids or moisture, is concerned. The implementation of the horn antenna method is dependent upon, amongst others, the resolution of the antenna in use. The present research work investigates the application of the GPR sensor technique to assess voids within the asphalt layers, with a focus on the air-coupled antenna penetration depth and resolution. For this purpose the dielectric properties of asphalt layer materials were estimated and related voids contents were evaluated based on data collected by an air-coupled GPR system, operating at a 1 GHz and alternatively a 2 GHz central frequency. The collected data is analyzed comparatively for the two antennas. Comparison results indicate differences between the voids determined from the 1 GHz and 2GHz antennas. These differences are further analyzed and evaluated for pavement quality control purposes. The indication of a relationship between the measured voids is also evaluated, while ground truth data is used for the validation of the GPR data analysis results. The above is presented and discussed thoroughly with the aim to assist pavement quality assurance systems

  9. Effect of flexibility on the performance of an impulsively started foil

    NASA Astrophysics Data System (ADS)

    Saadat, Mehdi; Haj-Hariri, Hossein

    2014-11-01

    A computational study is conducted to investigate the effects of flexibility on the unsteady forces of an impulsively started foil. The flexibility is implemented into the model by allowing the rigid foil to rotate (pitch) about its leading edge. First, for a given initial angle of attack, the pitching motion of the foil is prescribed by imposing various constant angular velocities. It is shown that thrust window (i.e. the duration of which thrust is generated as defined by Wang 2000) and the value of maximum thrust is maximized at an optimum angular velocity. Next, the foil is allowed to rotate freely around its leading edge. The force balance of fluid added mass with the foil inertia predicts the solid-to-fluid density ratio required for achieving the optimum angular velocity, and maximizing the thrust widow and maximum thrust. Computations further confirm the optimum density ratio derived by the scaling analysis. We hypothesize that a flexible fin achieves its best performance when the fin is limp, and its solid-to-fluid density ratio is set to the optimum value. We provide comparison with data from biology. Z. J. Wang, J. Fluid Mech. 410, 323 (2000).

  10. High performance dual-wave mode flexible surface acoustic wave resonators for UV light sensing

    NASA Astrophysics Data System (ADS)

    He, X. L.; Zhou, J.; Wang, W. B.; Xuan, W. P.; Yang, X.; Jin, H.; Luo, J. K.

    2014-05-01

    Dual-mode flexible ZnO/polyimide surface acoustic wave (SAW)-based ultraviolet (UV) light sensors were fabricated and their performance was investigated. UV light sensing measurements showed that the responses of the dual wave modes of the sensors increase with the increase of light intensity and the frequency changes linearly with the change of light intensity. Under a 4.5 mW cm-2 UV light illumination, the resonant frequency of the Rayleigh wave decreased up to 43 kHz, while that of the Lamb wave was approximately 76 kHz. The UV light sensitivities for the two resonant modes are 111.3 and 55.8 ppm (mW cm-2)-1, respectively. The resonant frequency, phase angle and amplitude of the two resonant modes exhibited a good repeatability in responding to cyclic change of the UV light, and an excellent stability up to a long duration of UV light exposure. The dual-mode flexible SAW resonators are simple in structure, more accurate in detection, and can be fabricated at low cost are, therefore, very promising for application in flexible sensors and electronics.

  11. A systematic investigation of polymer binder flexibility on the electrode performance of lithium-ion batteries.

    PubMed

    Yuca, Neslihan; Zhao, Hui; Song, Xiangyun; Dogdu, Murat Ferhat; Yuan, Wen; Fu, Yanbao; Battaglia, Vincent S; Xiao, Xingcheng; Liu, Gao

    2014-10-01

    The mechanical failure at the electrode interfaces (laminate/current collector and binder/particle interfaces) leads to particle isolation and delamination, which has been regarded as one of the main reasons for the capacity decay and cell failure of lithium-ion batteries (LIBs). Polymer binder provides the key function for a good interface property and for maintaining the electrode integrity of LIBs. Triethylene glycol monomethyl ether (TEG) moieties were incorporated into polymethacrylic acid (PMAA) to different extents at the molecular level. Microscratch tests of the graphite electrodes based on these binders indicate that the electrode is more flexible with 5 or 10% TEG in the polymer binders. Crack generation is inhibited by the flexible TEG-containing binder, compared to that of the unmodified PMAA-based electrode, leading to the better cycling performance of the flexible electrode. With a 10% TEG moiety in the binder, the graphite half-cell reaches a reversible capacity of >270 mAh/g at the 1C rate, compared to a value of ∼190 mAh/g for the unmodified PMAA binder. PMID:25203598

  12. High-performance flexible graphene aptasensor for mercury detection in mussels.

    PubMed

    An, Ji Hyun; Park, Seon Joo; Kwon, Oh Seok; Bae, Joonwon; Jang, Jyongsik

    2013-12-23

    Mercury (Hg) is highly toxic but has been widely used for numerous domestic applications, including thermometers and batteries, for decades, which has led to fatal outcomes due to its accumulation in the human body. Although many types of mercury sensors have been developed to protect the users from Hg, few methodologies exist to analyze Hg(2+) ions in low concentrations in real world samples. Herein, we describe the fabrication and characterization of liquid-ion gated field-effect transistor (FET)-type flexible graphene aptasensor with high sensitivity and selectivity for Hg. The field-induced responses from the graphene aptasensor had excellent sensing performance, and Hg(2+) ions with very low concentration of 10 pM could be detected, which is 2-3 orders of magnitude more sensitive than previously reported mercury sensors using electrochemical systems. Moreover, the aptasensor showed a highly specific response to Hg(2+) ions in mixed solutions. The flexible graphene aptasensor showed a very rapid response, providing a signal in less than 1 s when the Hg(2+) ion concentration was altered. Specificity to Hg(2+) ions was demonstrated in real world samples (in this case samples derived from mussels). The aptasensor was fabricated by transferring chemical vapor deposition (CVD)-grown graphene onto a transparent flexible substrate, and the structure displayed excellent mechanical durability and flexiblility. This graphene-based aptasensor has potential for detecting Hg exposure in human and in the environment. PMID:24279823

  13. Graphene/carbon black hybrid film for flexible and high rate performance supercapacitor

    NASA Astrophysics Data System (ADS)

    Wang, Yaming; Chen, Junchen; Cao, Jianyun; Liu, Yan; Zhou, Yu; Ouyang, Jia-Hu; Jia, Dechang

    2014-12-01

    Reduced graphene oxide/carbon black (rGO/CB) hybrid films with different carbon black (CB) contents are prepared by a simple vacuum filtration method. The CB particles evenly distribute between the graphene layers, not only preventing the compact restack of rGO sheets but also providing electrical contact between the base planes of rGO sheets. As expected, the as-prepared rGO/CB hybrid film shows enhanced rate capability when compared with rGO film. Furthermore, a solid-state flexible supercapacitor has been constructed with the optimized rGO/CB hybrid film by using polyvinyl alcohol (PVA)/H2SO4 gel as electrolyte and Au coated PET film as current collector and mechanical support. The solid-state flexible supercapacitor shows a specific capacitance of 112 F g-1 at a scan rate of 5 mV s-1, and excellent rate performance with a specific capacitance of 79.6 F g-1 at a high scan rate of 1 V s-1. Moreover, the flexible solid-state supercapacitor exhibits good cycling stability with capacitance retention of 94% after 3000 cycles in normal state plus 2000 cycles in bent state.

  14. Study of flexible fin and compliant joint stiffness on propulsive performance: theory and experiments.

    PubMed

    Kancharala, A K; Philen, M K

    2014-09-01

    The caudal fin is a major source of thrust generation in fish locomotion. Along with the fin stiffness, the stiffness of the joint connecting the fish body to the tail plays a major role in the generation of thrust. This paper investigates the combined effect of fin and joint flexibility on propulsive performance using theoretical and experimental studies. For this study, fluid-structure interaction of the fin has been modeled using the 2D unsteady panel method coupled with nonlinear Euler-Bernoulli beam theory. The compliant joint has been modeled as a torsional spring at the leading edge of the fin. A comparison of self-propelled speed and efficiency with parameters such as heaving and pitching amplitude, oscillation frequency, flexibility of the fin and the compliant joint is reported. The model also predicts the optimized stiffnesses of the compliant joint and the fin for maximum efficiency. Experiments have been carried out to determine the effect of fin and joint stiffness on propulsive performance. Digital image correlation has been used to measure the deformation of the fins and the measured deformation is coupled with the hydrodynamic model to predict the performance. The predicted theoretical performance behavior closely matches the experimental values. PMID:24737004

  15. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-11-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them.

  16. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices.

    PubMed

    Polat, Emre O; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm(2) flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  17. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    PubMed Central

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  18. Evaluation of non-metallic fiber reinforced concrete in new full depth pcc pavements. Final report

    SciTech Connect

    Ramakrishnan, V.; Tolmare, N.S.

    1998-12-30

    This final report presents the construction and performance evaluation of a new full depth pavement, constructed with a new type non-metallic fiber reinforced concrete (NMFRC). The mixture proportions used, the quality control tests conducted for the evaluation of the fresh and hardened concrete properties, the procedure used for mixing, transporting, placing, consolidating, finishing, and curing of the concrete are described. Periodic inspection of the full depth pavement was done and this report includes the results of these inspections. The feasibility of using this NMFRC in the construction of highway structures has been discussed. The new NMFRC with enhanced fatigue, impact resistance, modulus of rupture, ductility and toughness properties is suitable for the construction of full depth pavements. However, a life-cycle cost analysis shows that NMFRC is not a favorable choice, because of it`s high initial cost.

  19. The behavior of a novel raw material-encapsulated FBG sensor for pavement monitoring

    NASA Astrophysics Data System (ADS)

    Wang, Huaping; Liu, Wanqiu; Zhou, Zhi; Wang, Shuhong; Li, Yuan

    2011-11-01

    Technology on pavement monitoring has been paid more and more attention by government, engineers and scholars. Conventional methods, such as artificial inspection and core sampling, have defect in low efficiency and limited coverage, and modern technologies, such as spectrum analysis and integral imaging, have poor resistance to external interference and high cost, which reveals that common approaches have fallen behind the development of road engineering. Therefore, a novel raw material-encapsulated FBG strain sensor is put forward, thinking over outstanding advantages of fiber Bragg grating and perfect incorporation between coating layers and host layers. Numerical analysis and experiments have been done to inspect behavior of the sensing system. Results indicate that it can well detect the actual performance of pavements, and the sensor presents a high-precision, real-time and long-term monitoring, owning function of road disaster warming, which promise it an extensive future in pavement monitoring.

  20. Breaking/cracking and seating concrete pavements. Final report

    SciTech Connect

    Thompson, M.R.

    1989-03-01

    This synthesis will be of interest to pavement designers, maintenance engineers, and others interested in reducing reflection cracking of asphalt overlays on portland cement concrete (PCC) pavement. Information is presented on the technique of breaking or cracking of the concrete pavement into small segments before overlaying with asphalt concrete. Asphalt concrete overlays on existing PCC pavements are subject to reflection cracking induced by thermal movements of PCC pavement. The report of the Transportation Research Board discusses the technique of breaking/cracking and seating of the existing PCC before an overlay as a means to reduce or eliminate reflection cracking.

  1. Micro-thermal stress analysis of cement based pavement composite

    SciTech Connect

    Li, G.; Zhao, Y.; Pang, S.S.; Huang, W.

    1998-12-31

    A four-layer sphere model for microscopic thermal analysis was proposed based upon the structural form of cement based pavement composites. Using temperature induced stresses of pavement structure as the external field, the micro-thermal stresses of two types of cement based pavement composite were calculated. The results showed that, by introducing the low stiffness rubberized asphalt in the interphase of coarse aggregate phase and cement mortar phase of Portland cement concrete, the interfacial thermal stresses could be reduced significantly, thus improving crack resistance of the pavement material under low temperature environment. Factors affecting micro-thermal stress of cement based pavement composite were discussed.

  2. User's guide: Cold-mix recycling of asphalt concrete pavements. Final report

    SciTech Connect

    Shoenberger, J.E.

    1992-09-01

    This guide provides the technical information required to implement the application of cold-mix recycling of asphalt concrete pavements. Included are details on areas on application, benefits/advantages, limitations/disadvantages, and costs associated with this technology. Information is provided on two demonstration sites at Fort Gillem, Georgia, and Fort Leavenworth, Kansas. Also provided is information concerning funding, procurement, maintenance, and performance monitoring. A fact sheet on recycling, contract specification example, and references are provided in the appendixes.... Asphalt pavement recycling, Emulsified asphalt cement, Cold milling, In-place cold-mix asphalt recycling, Cold-mix asphalt recycling, Recycling of asphalt.

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

    USGS Publications Warehouse

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

    2012-01-01

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

  4. High-Performance Flexible Organic Nano-Floating Gate Memory Devices Functionalized with Cobalt Ferrite Nanoparticles.

    PubMed

    Jung, Ji Hyung; Kim, Sunghwan; Kim, Hyeonjung; Park, Jongnam; Oh, Joon Hak

    2015-10-01

    Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2O4) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read I(on)/I(off)) of ≈2.98 × 10(3), and excellent data retention. Fast switching behaviors are observed due to the exceptional charge trapping/release capability of CoFe2O4 NPs surrounded by the oleate layer, which acts as an alternative tunneling dielectric layer and simplifies the device fabrication process. Furthermore, the NFGM devices show excellent thermal stability, and flexible memory devices fabricated on plastic substrates exhibit remarkable mechanical and electrical stability. This study demonstrates a viable means of fabricating highly flexible, high-performance organic memory devices. PMID:26153227

  5. Terra Flexible Blanket Solar Array Deployment, On-Orbit Performance and Future Applications

    NASA Technical Reports Server (NTRS)

    Kurland, Richard; Schurig, Hans; Rosenfeld, Mark; Herriage, Michael; Gaddy, Edward; Keys, Denney; Faust, Carl; Andiario, William; Kurtz, Michelle; Moyer, Eric; Day, John H. (Technical Monitor)

    2000-01-01

    The Terra spacecraft (formerly identified as EOS AM1) is the flagship in a planned series of NASA/GSFC (Goddard Space Flight Center) Earth observing system satellites designed to provide information on the health of the Earth's land, oceans, air, ice, and life as a total ecological global system. It has been successfully performing its mission since a late-December 1999 launch into a 705 km polar orbit. The spacecraft is powered by a single wing, flexible blanket array using single junction (SJ) gallium arsenide/germanium (GaAs/Ge) solar cells sized to provide five year end-of-life (EOL) power of greater than 5000 watts at 127 volts. It is currently the highest voltage and power operational flexible blanket array with GaAs/Ge cells. This paper briefly describes the wing design as a basis for discussing the operation of the electronics and mechanisms used to achieve successful on-orbit deployment. Its orbital electrical performance to date will be presented and compared to analytical predictions based on ground qualification testing. The paper concludes with a brief section on future applications and performance trends using advanced multi-junction cells and weight-efficient mechanical components.

  6. Terra Flexible Blanket Solar Array Deployment, On-Orbit Performance and Future Applications

    NASA Technical Reports Server (NTRS)

    Kurland, Richard; Schurig, Hans; Rosenfeld, Mark; Herriage, Michael; Gaddy, Edward; Keys, Denney; Faust, Carl; Andiario, William; Kurtz, Michelle; Moyer, Eric; Day, John H. (Technical Monitor)

    2000-01-01

    The Terra spacecraft (formerly identified as EOS AM1) is the flagship in a planned series of NASA/GSFC (Goddard Space Flight Center) Earth observing system satellites designed to provide information on the health of the Earth's land, oceans, air, ice, and life as a total ecological global system. It has been successfully performing its mission since a late-December 1999 launch into a 705 km polar orbit. The spacecraft is powered by a single wing, flexible blanket array using single junction (SJ) gallium arsenide/germanium (GaAs/Ge) solar cells sized to provide five year end-of-life (EOL) power of greater than 5000 watts at 127 volts. It is currently the highest voltage and power operational flexible blanket array with GaAs/Ge cells. This paper briefly describes the wing design as a basis for discussing the operation of the electronics and mechanisms used to achieve successful on-orbit deployment. Its orbital electrical performance to date will be presented and compared to analytical predictions based on ground qualification testing. The paper concludes with a brief section on future applications and performance trends using advanced multi-junction cells and weight-efficient mechanical components. A viewgraph presentation is attached that outlines the same information as the paper and includes more images of the Terra Spacecraft and its components.

  7. Modeling and performance evaluation of flexible manufacturing systems using Petri nets

    SciTech Connect

    Callotta, M.P.; Cimenez, C.; Tazza, M.

    1996-12-31

    A timed Petri net approach is used to model resource allocation-utilization-release patterns for performance evaluation. First, simple resource utilization sequences are derived from a directed graph representing the process plan of parts. Second, the place-transitions sequences are connected introducing places whose marking models the resources needed to perform the manufacturing operation indicated in the process plan. Time is introduced as a permanence time of tokens at the place-transition sequence, modeling the utilization time of resources. The corresponding model leads to a simultaneous resource possession problem. Finally, flow equations for the description of the quantitative behavior of the resulting timed Petri net are presented. A major conclusion of the paper is that performance evaluation can be adequately abstracted and analytically solved, in a simple way, even in presence of complicating factors like resource sharing and routing flexibility in process plans.

  8. Permeable pavement research – Edison, New Jersey

    EPA Science Inventory

    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...

  9. Reconstruction of a pavement geothermal deicing system

    SciTech Connect

    Lund, J.W.

    1999-03-01

    In 1948, US 97 in Klamath Falls, Oregon was routed over Esplanade Street to Main Street and through the downtown area. In order to widen the bridge across the US Bureau of Reclamation A Canal and to have the road cross under the Southern Pacific Railroad main north-south line, a new bridge and roadway were constructed at the beginning of this urban route. Because the approach and stop where this roadway intersected Alameda Ave (now Hwy 50 -- Eastside Bypass) caused problems with traffic getting traction in the winter on an adverse 8% grade, a geothermal experiment in pavement de-icing was incorporated into the project. A grid system within the pavement was connected to a nearby geothermal well using a downhole heat exchanger (DHE). The 419-foot well provided heat to a 50-50 ethylene glycol-water solution that ran through the grid system at about 50 gpm. This energy could provide a relatively snow free pavement at an outside temperature of {minus}10 F and snowfall up to 3 inches per hour, at a heat requirement of 41 Btu/hr/ft{sup 2}. Over time, the well temperature dropped from 143 to 98 F at the surface. The bridge and surface pavement, geothermal well, and associated equipment were modified. This paper describes the modifications.

  10. Desert pavement study at Amboy, California

    NASA Technical Reports Server (NTRS)

    Williams, S.; Greeley, R.

    1984-01-01

    Desert pavement is a general term describing a surface that typically consists of a thin layer of cm-sized rock fragments set on top of a layer of finer material in which no fragments are found. An understanding of desert pavement is important to planetary geology because they may play a major role in the formation and visibility of various aeolian features such as wind streaks, which are important on Mars and may be important on Venus. A field study was conducted in Amboy, California to determine the formation mechanism of desert pavements. The probable sequence of events for the formation and evolution of a typical desert pavement surface, based on this experiment and the work of others, is as follows. Starting with a layer of surface material consisting of both fine particles and rock fragments, aeolian deflation will rapidly erode the surface until an armored lag is developed, after which aeolian processes become less important. The concentration of fragments then slowly increases as new fragments are brought to the surface from the subsurface and as fragments move downslope by sheet wash. Sheet wash would be responsible for removing very fine particles from the surface and for moving the fragments relative to one another, forming interlocks.

  11. Flexible Pillared Graphene-Paper Electrodes for High-Performance Electrochemical Supercapacitors

    SciTech Connect

    Wang, Gongkai; Sun, Xiang; Lu, Fengyuan; Sun, Hongtao; Yu, Mingpeng; Jiang, Weilin; Liu, Changsheng; Lian, Jie

    2011-12-08

    Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s-1, the specific capacitance of the pillared GP is 138 F g-1 and 83.2 F g-1 with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s-1, the specific capacitance can reach 80 F g-1 in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. Finally, the pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage.

  12. Experimental study on response performance of VIV of a flexible riser with helical strakes

    NASA Astrophysics Data System (ADS)

    Gao, Yun; Fu, Shi-xiao; Cao, Jing; Chen, Yi-fan

    2015-10-01

    Laboratory tests were conducted on a flexible riser with and without helical strakes. The aim of the present work is to further understand the response performance of the vortex induced vibration (VIV) for a riser with helical strakes. The experiment was accomplished in the towing tank and the relative current was simulated by towing a flexible riser in one direction. Based on the modal analysis method, the displacement responses can be obtained by the measured strain. The strakes with different heights are analyzed here, and the response parameters like strain response and displacement response are studied. The experimental results show that the in-line (IL) response is as important as the cross-flow (CF) response, however, many industrial analysis methods usually ignore the IL response due to VIV. The results also indicate that the response characteristics of a bare riser can be quite distinct from that of a riser with helical strakes, and the response performance depends on the geometry on the helical strakes closely. The fatigue damage is further discussed and the results show that the fatigue damage in the CF direction is of the same order as that in the IL direction for the bare riser. However, for the riser with helical strakes, the fatigue damage in the CF direction is much smaller than that in the IL direction.

  13. Performance testing of the 5 kW EOS AM-1 flexible solar array blanket

    SciTech Connect

    Schurig, H.H.; Kruer, M.A.; Levesque, M.N.; Gaddy, E.M.

    1997-12-31

    A GaAs/Ge flexible solar array blanket has been developed for use on the NASA/GSFC remote sensing EOS AM-1 spacecraft. This single wing array has been designed to provide a 5 kW of power after five years in a low earth polar orbit. The blanket configuration includes design features such as thin GaAs/Ge cell stacks mounted on a large flexible, hinged substrate, parallel connected solar cell strings providing high voltage output, a printed circuit harness, and a multi-layer jumper bus providing electrical continuity between the cell strings and the printed circuit harness. This work was contracted to TRW Space and Electronics Group in 1993 by Lockheed Martin Missiles and Space (LMMS). This paper presents the essential design of the EOS AM-1 solar array blanket, and summarizes the results of a qualification test program designed to demonstrate adequate design margins and to assess the performance of the mechanical and electrical components after exposure to a simulated mission space environment. It also reviews the complexities of performing electrical output on a 8.9 m x 5.0 m deployed solar array blanket under AM0 conditions.

  14. Improvement of the aerodynamic performance by wing flexibility and elytra--hind wing interaction of a beetle during forward flight.

    PubMed

    Le, Tuyen Quang; Truong, Tien Van; Park, Soo Hyung; Quang Truong, Tri; Ko, Jin Hwan; Park, Hoon Cheol; Byun, Doyoung

    2013-08-01

    In this work, the aerodynamic performance of beetle wing in free-forward flight was explored by a three-dimensional computational fluid dynamics (CFDs) simulation with measured wing kinematics. It is shown from the CFD results that twist and camber variation, which represent the wing flexibility, are most important when determining the aerodynamic performance. Twisting wing significantly increased the mean lift and camber variation enhanced the mean thrust while the required power was lower than the case when neither was considered. Thus, in a comparison of the power economy among rigid, twisting and flexible models, the flexible model showed the best performance. When the positive effect of wing interaction was added to that of wing flexibility, we found that the elytron created enough lift to support its weight, and the total lift (48.4 mN) generated from the simulation exceeded the gravity force of the beetle (47.5 mN) during forward flight. PMID:23740486

  15. Improvement of the aerodynamic performance by wing flexibility and elytra–hind wing interaction of a beetle during forward flight

    PubMed Central

    Le, Tuyen Quang; Truong, Tien Van; Park, Soo Hyung; Quang Truong, Tri; Ko, Jin Hwan; Park, Hoon Cheol; Byun, Doyoung

    2013-01-01

    In this work, the aerodynamic performance of beetle wing in free-forward flight was explored by a three-dimensional computational fluid dynamics (CFDs) simulation with measured wing kinematics. It is shown from the CFD results that twist and camber variation, which represent the wing flexibility, are most important when determining the aerodynamic performance. Twisting wing significantly increased the mean lift and camber variation enhanced the mean thrust while the required power was lower than the case when neither was considered. Thus, in a comparison of the power economy among rigid, twisting and flexible models, the flexible model showed the best performance. When the positive effect of wing interaction was added to that of wing flexibility, we found that the elytron created enough lift to support its weight, and the total lift (48.4 mN) generated from the simulation exceeded the gravity force of the beetle (47.5 mN) during forward flight. PMID:23740486

  16. Monitoring Strategies in Permeable Pavement Systems to Optimize Maintenance Scheduling - abstract

    EPA Science Inventory

    As the surface in a permeable pavement system clogs and performance decreases, maintenance is required to preserve the design function. Currently, guidance is limited for scheduling maintenance on an as needed basis. Previous research has shown that surface clogging in a permea...

  17. Carbon nanotube bundles/polystyrene composites as high-performance flexible thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Suemori, Kouji; Watanabe, Yuichi; Hoshino, Satoshi

    2015-03-01

    Lightweight and flexible thermoelectric devices consisting of carbon nanotube (CNT)-based materials have the potential to be used for the various applications, such as energy harvesting from the low-temperature waste heat that exists ubiquitously in living areas. Because high-performance CNT-based materials are crucial for the broad-ranging employment of CNT-based thermoelectric devices, considerable efforts are being made to improve the power-generation capability of CNT-based thermoelectric materials. Here, we report high-performance thermoelectric composites consisting of CNT bundles and polystyrene fabricated by a planetary ball milling-based dispersion technique, which allows for the direct dispersion of the CNT bundles within the polystyrene matrix without causing the disaggregation of the bundled CNTs into individual ones. The CNT-bundles/polystyrene composites reported here exhibit a power factor of 413 ?W/K2.m.

  18. Performance limitations of joint variable-feedback controllers due to manipulator structural flexibility

    NASA Technical Reports Server (NTRS)

    Cetinkunt, Sabri; Book, Wayne J.

    1990-01-01

    The performance limitations of manipulators under joint variable-feedback control are studied as a function of the mechanical flexibility inherent in the manipulator structure. A finite-dimensional time-domain dynamic model of a two-link two-joint planar manipulator is used in the study. Emphasis is placed on determining the limitations of control algorithms that use only joint variable-feedback information in calculations of control decisions, since most motion control systems in practice are of this kind. Both fine and gross motion cases are studied. Results for fine motion agree well with previously reported results in the literature and are also helpful in explaining the performance limitations in fast gross motions.

  19. Ultrafast laser trimming for reduced device leakage in high performance OTFT semiconductors for flexible displays

    NASA Astrophysics Data System (ADS)

    Karnakis, Dimitris; Cooke, Michael D.; Chan, Y. F.; Ogier, Simon D.

    2013-03-01

    Organic semiconductors (OSC) are solution processable synthetic materials with high carrier mobility that promise to revolutionise flexible electronics manufacturing due to their low cost, lightweight and high volume low temperature printing in reel-to-reel (R2R) [1] for applications such as flexible display backplanes (Fig.1), RFID tags, and logic/memory devices. Despite several recent technological advances, organic thin film transistor (OTFT) printing is still not production-ready due to limitations mainly with printing resolution on dimensionally unstable substrates and device leakage that reduces dramatically electrical performance. OTFTs have the source-drain in ohmic contact with the OSC material to lower contact resistance. If they are unpatterned, a leakage pathway from source to drain develops which results in non-optimum on/off currents and not controllable device uniformity (Fig.2). DPSS lasers offer several key advantages for OTFT patterning including maskless, non-contact, dry patterning, scalable large area operation with precision registration, well-suited to R2R manufacturing at overall μm size resolutions. But the thermal management of laser processing is very important as the devices are very sensitive to heat and thermomechanical damage [2]. This paper discusses 343nm picosecond laser ablation trimming of 50nm thick PTAA, TIPS pentacene and other semiconductor compounds on thin 50nm thick metal gold electrodes in a top gate configuration. It is shown that with careful optimisation, a suitable process window exists resulting in clean laser structuring without damage to the underlying layers while also containing laser debris. Several order of magnitude improvements were recorded in on/off currents up to 106 with OSC mobilities of 1 cm2/Vsec, albeit at slightly higher than optimum threshold voltages which support demanding flexible display backplane applications.

  20. A quantitative performance measure for a clinical evaluation of comb structure removal algorithms in flexible endoscopy

    NASA Astrophysics Data System (ADS)

    Rupp, Stephan

    2008-03-01

    Modern techniques for technical inspection as well as medical diagnostics and therapy in keyhole-surgery scenarios make use of flexible endoscopes. Common to both application fields are very small natural or manmade entry points to the observed scene, as well as the complexity of the hollow itself. These make the use of rigid lens-based endoscopes or tip chip videoscopes impossible. Due to the fact that the fiber-optic image guide of a flexible endoscope introduces a comb structure to the acquired images, many research has been devoted to algorithms for an effective removal of such artifacts. Oftentimes, this research has been motivated by the fact, that the comb structure prevents an application of some well-established methods offered by the computer vision and image processing community. Unfortunately, the performance of the presented approaches are commonly visually evaluated or with respect to proprietary, non-standardized metrics. Thus, the performances of individual algorithms are hard to compare with each other. For this reasons, we propose a performance measure for fiber-optic imaging devices that has been motivated by the physics of optics. In this field, an optical system is frequently described by linear systems theory and the system's quality can be expressed by its transfer function. The determination of this transfer function has been standardized by the ISO for lens based imaging systems and represents a widely accepted measure for the quality of such systems. In this contribution, we present methods that account for fiber-optic imaging systems and thus enable a standardized performance evaluation. Finally, we demonstrate its use by comparing two recent state of the art comb structure removal algorithms, each of them being a representative of a spatial and a frequency domain method, respectively.

  1. High Performance All-Solid-State Flexible Micro-Pseudocapacitor Based on Hierarchically Nanostructured Tungsten Trioxide Composite.

    PubMed

    Huang, Xuezhen; Liu, Hewei; Zhang, Xi; Jiang, Hongrui

    2015-12-23

    Microsupercapacitors (MSCs) are promising energy storage devices to power miniaturized portable electronics and microelectromechanical systems. With the increasing attention on all-solid-state flexible supercapacitors, new strategies for high-performance flexible MSCs are highly desired. Here, we demonstrate all-solid-state, flexible micropseudocapacitors via direct laser patterning on crack-free, flexible WO3/polyvinylidene fluoride (PVDF)/multiwalled carbon nanotubes (MWCNTs) composites containing high levels of porous hierarchically structured WO3 nanomaterials (up to 50 wt %) and limited binder (PVDF, <25 wt %). The work leads to an areal capacitance of 62.4 mF·cm(-2) and a volumetric capacitance of 10.4 F·cm(-3), exceeding that of graphene based flexible MSCs by a factor of 26 and 3, respectively. As a noncarbon based flexible MSC, hierarchically nanostructured WO3 in the narrow finger electrode is essential to such enhancement in energy density due to its pseudocapacitive property. The effects of WO3/PVDF/MWCNTs composite composition and the dimensions of interdigital structure on the performance of the flexible MSCs are investigated. PMID:26618406

  2. Fabrication of high-performance flexible alkaline batteries by implementing multiwalled carbon nanotubes and copolymer separator.

    PubMed

    Wang, Zhiqian; Wu, Zheqiong; Bramnik, Natalia; Mitra, Somenath

    2014-02-12

    A flexible alkaline battery with multiwalled carbon nanotube (MWCNT) enhanced composite electrodes and polyvinyl alcohol (PVA)-poly (acrylic acid) (PAA) copolymer separator has been developed. Purified MWCNTs appear to be the most effective conductive additive, while the flexible copolymer separator not only enhances flexibility but also serves as electrolyte storage. PMID:24510667

  3. Scalable fabrication of high-performance and flexible graphene strain sensors.

    PubMed

    Tian, He; Shu, Yi; Cui, Ya-Long; Mi, Wen-Tian; Yang, Yi; Xie, Dan; Ren, Tian-Ling

    2014-01-21

    Graphene strain sensors have promising prospects of applications in detecting human motion. However, the shortage of graphene growth and patterning techniques has become a challenging issue hindering the application of graphene strain sensors. Therefore, we propose wafer-scale flexible strain sensors with high-performance, which can be fabricated in one-step laser scribing. The graphene films could be obtained by directly reducing graphene oxide film in a Light-Scribe DVD burner. The gauge factor (GF) of the graphene strain sensor (10 mm 10 mm square) is 0.11. In order to enhance the GF further, graphene micro-ribbons (20 ?m width, 0.6 mm long) has been used as strain sensors, of which the GF is up to 9.49. The devices may conform to various application requirements, such as high GF for low-strain applications and low GF for high deformation applications. The work indicates that laser scribed flexible graphene strain sensors could be widely used in medical-sensing, bio-sensing, artificial skin and many other areas. PMID:24281713

  4. High-Performance GaAs Nanowire Solar Cells for Flexible and Transparent Photovoltaics.

    PubMed

    Han, Ning; Yang, Zai-xing; Wang, Fengyun; Dong, Guofa; Yip, SenPo; Liang, Xiaoguang; Hung, Tak Fu; Chen, Yunfa; Ho, Johnny C

    2015-09-16

    Among many available photovoltaic technologies at present, gallium arsenide (GaAs) is one of the recognized leaders for performance and reliability; however, it is still a great challenge to achieve cost-effective GaAs solar cells for smart systems such as transparent and flexible photovoltaics. In this study, highly crystalline long GaAs nanowires (NWs) with minimal crystal defects are synthesized economically by chemical vapor deposition and configured into novel Schottky photovoltaic structures by simply using asymmetric Au-Al contacts. Without any doping profiles such as p-n junction and complicated coaxial junction structures, the single NW Schottky device shows a record high apparent energy conversion efficiency of 16% under air mass 1.5 global illumination by normalizing to the projection area of the NW. The corresponding photovoltaic output can be further enhanced by connecting individual cells in series and in parallel as well as by fabricating NW array solar cells via contact printing showing an overall efficiency of 1.6%. Importantly, these Schottky cells can be easily integrated on the glass and plastic substrates for transparent and flexible photovoltaics, which explicitly demonstrate the outstanding versatility and promising perspective of these GaAs NW Schottky photovoltaics for next-generation smart solar energy harvesting devices. PMID:26284305

  5. High performance solid state flexible supercapacitor based on molybdenum sulfide hierarchical nanospheres

    NASA Astrophysics Data System (ADS)

    Javed, Muhammad Sufyan; Dai, Shuge; Wang, Mingjun; Guo, Donglin; Chen, Lin; Wang, Xue; Hu, Chenguo; Xi, Yi

    2015-07-01

    Molybdenum sulfide (MoS2) hierarchical nanospheres are synthesized using a hydrothermal method and characterized by X-ray powder diffraction, Brunauer-Emmett-Teller, scanning electron microscopy and transmission electron microscopy. The prepared MoS2 is used to fabricate solid state flexible supercapacitors which show excellent electrochemical performance such as high capacitance 368 F g-1 at a scan rate of 5 mV s-1 and high power density of 128 W kg-1 at energy density of 5.42 Wh kg-1. The fabricated supercapacitor presents good characteristics such as lightweight, low cast, portability, high flexibility, and long term cycling stability by retaining 96.5% after 5000 cycles at constant discharge current of 0.8 mA. Electrochemical impedance spectroscopy (EIS) results reveal low resistance and suggest that MoS2 nanospheres would be a promising candidate for supercapacitors. Three charged supercapacitors connected in series can light 8 red color commercial light emitting diodes (LEDs) for 2 min, demonstrating its capability as a good storage device.

  6. Flexible Transparent Films Based on Nanocomposite Networks of Polyaniline and Carbon Nanotubes for High-Performance Gas Sensing.

    PubMed

    Wan, Pengbo; Wen, Xuemei; Sun, Chaozheng; Chandran, Bevita K; Zhang, Han; Sun, Xiaoming; Chen, Xiaodong

    2015-10-28

    A flexible, transparent, chemical gas sensor is assembled from a transparent conducting film of carbon nanotube (CNT) networks that are coated with hierarchically nanostructured polyaniline (PANI) nanorods. The nanocomposite film is synthesized by in-situ, chemical oxidative polymerization of aniline in a functional multiwalled CNT (FMWCNT) suspension and is simultaneously deposited onto a flexible polyethylene terephthalate (PET) substrate. An as-prepared flexible transparent chemical gas sensor exhibits excellent transparency of 85.0% at 550 nm using the PANI/FMWCNT nanocomposite film prepared over a reaction time of 8 h. The sensor also shows good flexibility, without any obvious decrease in performance after 500 bending/extending cycles, demonstrating high-performance, portable gas sensing at room temperature. This superior performance could be attributed to the improved electron transport and collection due to the CNTs, resulting in reliable and efficient sensing, as well as the high surface-to-volume ratio of the hierarchically nanostructured composites. The excellent transparency, improved sensing performance, and superior flexibility of the device, may enable the integration of this simple, low-cost, gas sensor into handheld flexible transparent electronic circuitry and optoelectronic devices. PMID:26294393

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

    NASA Astrophysics Data System (ADS)

    Plati, Christina; Georgiou, Panos; Loizos, Andreas

    2013-04-01

    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.

  8. Final Technical Report, Oct 2004 - Nov. 2006, High Performance Flexible Reversible Solid Oxide Fuel Cell

    SciTech Connect

    Guan, Jie; Minh, Nguyen

    2007-02-21

    This report summarizes the work performed for the program entitled “High Performance Flexible Reversible Solid Oxide Fuel Cell” under Cooperative Agreement DE-FC36-04GO14351 for the U. S. Department of Energy. The overall objective of this project is to demonstrate a single modular stack that generates electricity from a variety of fuels (hydrogen and other fuels such as biomass, distributed natural gas, etc.) and when operated in the reverse mode, produces hydrogen from steam. This project has evaluated and selected baseline cell materials, developed a set of materials for oxygen and hydrogen electrodes, and optimized electrode microstructures for reversible solid oxide fuel cells (RSOFCs); and demonstrated the feasibility and operation of a RSOFC multi-cell stack. A 10-cell reversible SOFC stack was operated over 1000 hours alternating between fuel cell (with hydrogen and methane as fuel) and steam electrolysis modes. The stack ran very successfully with high power density of 480 mW/cm2 at 0.7V and 80% fuel utilization in fuel cell mode and >6 SLPM hydrogen production in steam electrolysis mode using about 1.1 kW electrical power. The hydrogen generation is equivalent to a specific capability of 2.59 Nm3/m2 with electrical energy demand of 3 kWh/Nm3. The performance stability in electrolysis mode was improved vastly during the program with a degradation rate reduction from 8000 to 200 mohm-cm2/1000 hrs. This was accomplished by increasing the activity and improving microstructure of the oxygen electrode. Both cost estimate and technology assessment were conducted. Besides the flexibility running under both fuel cell mode and electrolysis mode, the reversible SOFC system has the potentials for low cost and high efficient hydrogen production through steam electrolysis. The cost for hydrogen production at large scale was estimated at ~$2.7/kg H2, comparing favorably with other electrolysis techology.

  9. High performance low temperature carbon composite catalysts for flexible dye sensitized solar cells.

    PubMed

    Hashmi, Syed Ghufran; Halme, Janne; Saukkonen, Tapio; Rautama, Eeva-Leena; Lund, Peter

    2013-10-28

    Roll-to-roll manufacturing of dye sensitized solar cells (DSSCs) requires efficient and low cost materials that adhere well on the flexible substrates used. In this regard, different low temperature carbon composite counter electrode (CE) catalyst ink formulations for flexible DSSCs were developed that can be simply and quickly coated on plastic substrates and dried below 150 °C. The CEs were investigated in terms of photovoltaic performance in DSSCs by current-voltage measurements, mechanical adhesion properties by bending and tape tests, electro-catalytic performance by electrochemical impedance spectroscopy and microstructure by electron microscopy. In the bending and tape tests, PEDOT-carbon composite catalyst layers exhibited higher elasticity and better adhesion on all the studied substrates (ITO-PET and ITO-PEN plastic, and FTO-glass), compared to a binder free carbon composite and a TiO2 binder enriched carbon composite, and showed lower charge transfer resistance (1.5-3 Ω cm(2)) than the traditional thermally platinized CE (5 Ω cm(2)), demonstrating better catalytic performance for the tri-iodide reduction reaction. Also the TiO2 binder enriched carbon composite showed good catalytic characteristics and relatively good adhesion on ITO-PET, but on ITO-PEN its adhesion was poor. A DSSC with the TiO2 binder enriched catalyst layer reached 85% of the solar energy conversion efficiency of the reference DSSC based on the traditional thermally platinized CE. Based on the aforementioned characteristics, these carbon composites are promising candidates for replacing the platinum catalyst in a high volume roll-to-roll manufacturing process of DSSCs. PMID:24042582

  10. Can We Build a Truly High Performance Computer Which is Flexible and Transparent?

    PubMed Central

    Rojas, Jhonathan P.; Torres Sevilla, Galo A.; Hussain, Muhammad M.

    2013-01-01

    State-of-the art computers need high performance transistors, which consume ultra-low power resulting in longer battery lifetime. Billions of transistors are integrated neatly using matured silicon fabrication process to maintain the performance per cost advantage. In that context, low-cost mono-crystalline bulk silicon (100) based high performance transistors are considered as the heart of today's computers. One limitation is silicon's rigidity and brittleness. Here we show a generic batch process to convert high performance silicon electronics into flexible and semi-transparent one while retaining its performance, process compatibility, integration density and cost. We demonstrate high-k/metal gate stack based p-type metal oxide semiconductor field effect transistors on 4 inch silicon fabric released from bulk silicon (100) wafers with sub-threshold swing of 80 mV dec−1 and on/off ratio of near 104 within 10% device uniformity with a minimum bending radius of 5 mm and an average transmittance of ~7% in the visible spectrum. PMID:24018904

  11. Can we build a truly high performance computer which is flexible and transparent?

    PubMed

    Rojas, Jhonathan P; Torres Sevilla, Galo A; Hussain, Muhammad M

    2013-01-01

    State-of-the art computers need high performance transistors, which consume ultra-low power resulting in longer battery lifetime. Billions of transistors are integrated neatly using matured silicon fabrication process to maintain the performance per cost advantage. In that context, low-cost mono-crystalline bulk silicon (100) based high performance transistors are considered as the heart of today's computers. One limitation is silicon's rigidity and brittleness. Here we show a generic batch process to convert high performance silicon electronics into flexible and semi-transparent one while retaining its performance, process compatibility, integration density and cost. We demonstrate high-k/metal gate stack based p-type metal oxide semiconductor field effect transistors on 4 inch silicon fabric released from bulk silicon (100) wafers with sub-threshold swing of 80 mV dec(-1) and on/off ratio of near 10(4) within 10% device uniformity with a minimum bending radius of 5 mm and an average transmittance of ~7% in the visible spectrum. PMID:24018904

  12. Effects of labeling on preschoolers' explicit false belief performance: outcomes of cognitive flexibility or inhibitory control?

    PubMed

    Low, Jason; Simpson, Samantha

    2012-01-01

    Executive function mechanisms underpinning language-related effects on theory of mind understanding were examined in a sample of 165 preschoolers. Verbal labels were manipulated to identify relevant perspectives on an explicit false belief task. In Experiment 1 with 4-year-olds (N = 74), false belief reasoning was superior in the fully and protagonist-perspective labeled conditions compared to the child-perspective and nondescript labeling conditions. In Experiment 2 with 3-year-olds (N = 53), labeling the nondominant belief only biased attentional inertia. In Experiment 3 testing generalization in 4-year-olds (N = 38), labeling manipulations translated to improved performance on a second label-free explicit false belief task. These outcomes fit a cognitive flexibility account whereby age changes in the effects of labeling turn on formulating sophisticated conceptual representations. PMID:22364371

  13. Influence of landing gear flexibility on aircraft performance during ground roll

    NASA Technical Reports Server (NTRS)

    Sivaramakrishnan, M. M.

    1981-01-01

    An analysis is made of the influence of landing gear deflection characteristics on aircraft performance on the ground up to rotation. A quasi-steady dynamic equilibrium state is assumed, including other simplifying assumptions such as calm air conditions and normal aircraft lift and drag. Ground incidence is defined as the angle made by the mean aerodynamic chord of the wing with respect to the ground plane, and equations are given for force and balance which determine the quasi-equilibrium conditions for the aircraft during ground roll. Results indicate that the landing gear deflections lead to a substantial increase in the angle of attack, and the variation in the ground incidence due to landing gear flexibility could be as much as + or - 50%, and the reduction in tail load requirements almost 25%.

  14. Effect of Lumbar Spine Manipulation on Asymptomatic Cyclist Sprint Performance and Hip Flexibility

    PubMed Central

    Olson, Eric; Bodziony, Michael; Ward, John; Coats, Jesse; Koby, Bradley; Goehry, Doug

    2014-01-01

    Objective The purpose of this study was to measure the impact of midlumbar spinal manipulation on asymptomatic cyclist sprint performance and hip flexibility. Methods Twelve cyclists were equally randomized into an AB:BA crossover study design after baseline testing. Six participants were in the AB group, and 6 were in the BA group. The study involved 1 week of rest in between each of the 3 tested conditions: baseline testing (no intervention prior to testing), condition A (bilateral midlumbar spine manipulation prior to testing), and condition B (sham acupuncture prior to testing, as a control). Testing was blinded and involved a sit-and-reach test followed by a 0.5-km cycle ergometer sprint test against 4-kp resistance. Outcome measures were sit-and-reach distance, time to complete 0.5 km, maximum heart rate, and rating of perceived exertion. An additional 8 cyclists were recruited and used as a second set of controls that engaged in 3 testing sessions without any intervention to track test acclimation. An analysis of variance was used to compare dependent variables under each of the 3 conditions for the experimental group and control group #1, and a repeated-measures analysis of variance was used to analyze test acclimation in control group #2. Results Lumbar spine manipulation did not demonstrate statistically significant between-group changes in sit-and-reach (P = .765), 0.5-km sprint performance time (P = .877), maximum exercise heart rate (P = .944), or rating of perceived exertion (P = .875). Conclusions The findings of this preliminary study showed that midlumbar spinal manipulation did not improve hip flexibility or cyclist power output of asymptomatic participants compared with an acupuncture sham and no-treatment control groups. PMID:25435836

  15. Flexible Electrode Design: Fabrication of Freestanding Polyaniline-Based Composite Films for High-Performance Supercapacitors.

    PubMed

    Khosrozadeh, Ali; Darabi, Mohammad Ali; Xing, Malcolm; Wang, Quan

    2016-05-11

    Polyaniline (PANI) is a promising pseudocapacitance electrode material. However, its structural instability leads to low cyclic stability and limited rate capability which hinders its practical applications. In view of the limitations, flexible PANI-based composite films are developed to improve the electrochemical performance of electrode materials. We report in the research a facile and cost-effective approach for fabrication of a high-performance supercapacitor (SC) with excellent cyclic stability and tunable energy and power densities. SC electrode containing a very high mass loading of active materials is a flexible film of PANI, tissue wiper-based cellulose, graphite-based exfoliated graphite (ExG), and silver nanoparticles with potential applications in wearable electronics. The optimum preparation weight ratios of silver nitrate/aniline and ExG/aniline used in the research are estimated to be 0.18 and 0.65 (or higher), respectively. Our results show that an ultrahigh capacitance of 3.84 F/cm(2) (240.10 F/g) at a discharge rate of 5 mA can be achieved. In addition, our study shows that the power density can be increased from 1531.3 to 3000 W/kg by selecting the weight ratio of ExG/aniline to be more than 0.65, with a sacrifice in the energy density. The obtained promising electrochemical properties are found to be mainly attributed to an effective combination of PANI, ExG, cushiony cellulose scaffold, and silver as well as the porosity of the composite. PMID:27116563

  16. Molecular mechanisms controlling pavement cell shape in Arabidopsis leaves.

    PubMed

    Qian, Pingping; Hou, Suiwen; Guo, Guangqin

    2009-08-01

    Pavement cells have an interlocking jigsaw puzzle-shaped leaf surface pattern. Twenty-three genes involved in the pavement cell morphogenesis were discovered until now. The mutations of these genes through various means lead to pavement cell shape defects, such as loss or lack of interdigitation, the reduction of lobing, gaps between lobe and neck regions in pavement cells, and distorted trichomes. These phenotypes are affected by the organization of microtubules and microfilaments. Microtubule bands are considered corresponding with the neck regions of the cell, while lobe formation depends on patches of microfilaments. The pathway of Rho of plant (ROP) GTPase signaling cascades regulates overall activity of the cytoskeleton in pavement cells. Some other proteins, in addition to the ROPs, SCAR/WAVE, and ARP2/3 complexes, are also involved in the pavement cell morphogenesis. PMID:19529941

  17. Thermal cracking of rubber modified pavements, May 1995. Final report

    SciTech Connect

    Raad, L.; Yuan, X.; Saboundjian, S.

    1995-05-01

    In accordance with the original ISTEA mandate (1991) to use crumb tire rubber in pavements, Alaska would be required to use about 250 tons of used tire rubber starting in 1994 and increasing to about 1,000 tons of rubber in 1997 and each year thereafter. A number of pavements using crumb rubber modifiers have been built in the state and have been in service for periods of 8 to 15 years. Knowledge of the behavior of these rubber-modified pavements under extreme climate conditions, particularly in relation to their low temperature cracking resistance, is necessary for future design and construction of rubberized pavements in Alaska. This report presents results of a study to determine the low temperature cracking resistance of rubber modified pavements in Alaska in comparison with conventional asphalt concrete pavements.

  18. Characterizing performances of solder paste printing process at flexible manufacturing lines

    SciTech Connect

    Siew, Jit Ping; Low, Heng Chin; Teoh, Ping Chow

    2015-02-03

    Solder paste printing (SPP) has been a challenge on printed circuit board (PCB) manufacturing, evident by the proliferation of solder paste inspection equipment, or substituted by rigorous non-value added activity of manual inspections. The objective of this study is to characterize the SPP performance of various products manufactured in flexible production lines with different equipment configurations, and determine areas for process improvement. The study began by collecting information on SPP performance relative to component placement (CP) process, and to the proportion of mixed products. Using a clustering algorithm to group similar elements together, SPP performance across all product-production line pairs are statistically modeled to discover the trend and the influential factors. The main findings are: (a) Ratio of overall dpku for CP and SPP processes are 2:1; (b) logistic regression models of SPP performance indicated that only effects of product-production line and solder paste printer configuration are significant; (c) PCB circuitry design with BGA components and single solder paste printer line configurations generated the highest monthly defects, with the highest variation in the latter.

  19. Assessing Green Infrastructure Performance Using Remote Hydologic Monitoring Measures

    EPA Science Inventory

    Two locations in Cincinnati were instrumented with level sensing technologies to measure stormwater flow in porous pavement and bioretention areas. Results indicate good performance of porous pavement and a cost effective application of technology to measure those flows. Result...

  20. Hybrid green permeable pave with hexagonal modular pavement systems

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  1. Lithium-doped zinc oxide nanowires-polymer composite for high performance flexible piezoelectric nanogenerator.

    PubMed

    Shin, Sung-Ho; Kim, Young-Hwan; Lee, Min Hyung; Jung, Joo-Yun; Seol, Jae Hun; Nah, Junghyo

    2014-10-28

    We present a method to develop high performance flexible piezoelectric nanogenerators (NGs) by employing Li-doped ZnO nanowires (NWs). We synthesized Li-doped ZnO NWs and adopted them to replace intrinsic ZnO NWs with a relatively low piezoelectric coefficient. When we exploited the ferroelectric phase transition induced in Li-doped ZnO NWs, the performance of the NGs was significantly improved and the NG fabrication process was greatly simplified. In addition, our approach can be easily expanded for large-scale NG fabrication. Consequently, the NGs fabricated by our simple method exhibit the excelling output voltage and current, which are stable and reproducible during periodic bending/releasing measurement over extended cycles. In addition, output voltage and current up to ∼ 180 V and ∼ 50 μA, respectively, were obtained in the large-scale NG. The approach introduced here extends the performance limits of ZnO-based NGs and their potentials in practical applications. PMID:25265473

  2. Enhanced thermoelectric performance of PEDOT:PSS flexible bulky papers by treatment with secondary dopants.

    PubMed

    Mengistie, Desalegn A; Chen, Chang-Hsiao; Boopathi, Karunakara M; Pranoto, Ferry W; Li, Lain-Jong; Chu, Chih-Wei

    2015-01-14

    For inorganic thermoelectric materials, Seebeck coefficient and electrical conductivity are interdependent, and hence optimization of thermoelectric performance is challenging. In this work we show that thermoelectric performance of PEDOT:PSS can be enhanced by greatly improving its electrical conductivity in contrast to inorganic thermoelectric materials. Free-standing flexible and smooth PEDOT:PSS bulky papers were prepared using vacuum-assisted filtration. The electrical conductivity was enhanced to 640, 800, 1300, and 1900 S cm(-1) by treating PEDOT:PSS with ethylene glycol, polyethylene glycol, methanol, and formic acid, respectively. The Seebeck coefficient did not show significant variation with the tremendous conductivity enhancement being 21.4 and 20.6 μV K(-1) for ethylene glycol- and formic acid-treated papers, respectively. This is because secondary dopants, which increase electrical conductivity, do not change oxidation level of PEDOT. A maximum power factor of 80.6 μW m(-1) K(-2) was shown for formic acid-treated samples, while it was only 29.3 μW m(-1) K(-2) for ethylene glycol treatment. Coupled with intrinsically low thermal conductivity of PEDOT:PSS, ZT ≈ 0.32 was measured at room temperature using Harman method. We investigated the reasons behind the greatly enhanced thermoelectric performance. PMID:25475257

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

    NASA Astrophysics Data System (ADS)

    Barton, B. R.

    1984-03-01

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

  4. Multimodal approach to seismic pavement testing

    USGS Publications Warehouse

    Ryden, N.; Park, C.B.; Ulriksen, P.; Miller, R.D.

    2004-01-01

    A multimodal approach to nondestructive seismic pavement testing is described. The presented approach is based on multichannel analysis of all types of seismic waves propagating along the surface of the pavement. The multichannel data acquisition method is replaced by multichannel simulation with one receiver. This method uses only one accelerometer-receiver and a light hammer-source, to generate a synthetic receiver array. This data acquisition technique is made possible through careful triggering of the source and results in such simplification of the technique that it is made generally available. Multiple dispersion curves are automatically and objectively extracted using the multichannel analysis of surface waves processing scheme, which is described. Resulting dispersion curves in the high frequency range match with theoretical Lamb waves in a free plate. At lower frequencies there are several branches of dispersion curves corresponding to the lower layers of different stiffness in the pavement system. The observed behavior of multimodal dispersion curves is in agreement with theory, which has been validated through both numerical modeling and the transfer matrix method, by solving for complex wave numbers. ?? ASCE / JUNE 2004.

  5. Enhanced electrochemical performance of polyaniline/carbon/titanium nitride nanowire array for flexible supercapacitor

    NASA Astrophysics Data System (ADS)

    Xie, Yibing; Xia, Chi; Du, Hongxiu; Wang, Wei

    2015-07-01

    The ternary nanocomposite of polyaniline/carbon/titanium nitride (PANI/C/TiN) nanowire array (NWA) is fabricated as electroactive electrode material for flexible supercapacitor application. Firstly, TiN NWA is formed through ammonia nitridation treatment of TiO2 NWA, which is synthesized via seed-assisted hydrothermal reaction. PANI/C/TiN NWA is then formed through sequentially coating carbon and PANI on the surface of TiN NWA. PANI/C/TiN NWA has unique shell/shell/core architecture, including a core layer of TiN NWA with a diameter of 40-160 nm and a length of 1.5 μm, a middle shell layer of carbon with a thickness of about 6.0 nm and an external surface layer of PANI with a thickness of 20-50 nm. PANI/C/TiN NWA provides ion diffusion channel at interspaces between the neighboring nanowires and electron transfer route along independent nanowires. The carbon shell layer is able to protect TiN NWA from electrochemical corrosion during charge/discharge process. PANI/C/TiN NWA displays high specific capacitance of 1093 F g-1 at 1.0 Ag-1, and good cycling stability with a capacity retention of 98% after 2000 cycles, presenting better supercapacitive performance than other integrated nanocomposites of C/PANI/TiN, PANI/TiN and PANI/C/TiO2 NWA. Such a ternary nanocomposite of PANI/C/TiN NWA can be used as an electrode material of flexible supercapacitors.

  6. Analysis of durability of advanced cementitious materials for rigid pavement construction in California

    SciTech Connect

    Kurtis, K.E.; Monteiro, P.

    1999-04-01

    Caltrans specifications for the construction of rigid pavements require rapid setting, high early strength, superior workability concrete with a desired 30+ year service life. These strict specifications provide the motivations for the investigation of advanced cementitious materials for pavement construction. The cementitious materials under consideration by Caltrans may be classified into four categories: Portland cements and blends, calcium aluminate cements and blends, calcium sulfoaluminate cements, and fly ash-based cements. To achieve the desired 30+ year design life, it is essential to select materials that are expected to exhibit long-term durability. Because most of the cementitious materials under consideration have not been extensively used for pavement construction in the United States, it is essential to characterize the long-term durability of each material. This report provides general information concerning the deleterious reactions that may damage concrete pavements in California. The reactions addressed in this report are sulfate attack, aggregate reactions, corrosion of reinforcing steel, and freeze-thaw action. Specifically, the expected performance of Portland cements and blends, calcium aluminate cements and blends, calcium sulfoaluminate cements, and fly ash-based cements are examined with regard to each of the deleterious reactions listed. Additional consideration is given to any deterioration mechanism that is particular to any of these cement types. Finally, the recommended test program for assessing potential long-term durability with respect to sulfate attack is described.

  7. High-performance carbon nanotube thin-film transistors on flexible paper substrates

    SciTech Connect

    Liu, Na; Yun, Ki Nam; Yu, Hyun-Yong; Lee, Cheol Jin; Shim, Joon Hyung

    2015-03-09

    Single-walled carbon nanotubes (SWCNTs) are promising materials as active channels for flexible transistors owing to their excellent electrical and mechanical properties. However, flexible SWCNT transistors have never been realized on paper substrates, which are widely used, inexpensive, and recyclable. In this study, we fabricated SWCNT thin-film transistors on photo paper substrates. The devices exhibited a high on/off current ratio of more than 10{sup 6} and a field-effect mobility of approximately 3 cm{sup 2}/V·s. The proof-of-concept demonstration indicates that SWCNT transistors on flexible paper substrates could be applied as low-cost and recyclable flexible electronics.

  8. Biofuel production system with operation flexibility: Evaluation of economic and environmental performance under external disturbance

    NASA Astrophysics Data System (ADS)

    Kou, Nannan

    Biomass derived liquid hydrocarbon fuel (biofuel) has been accepted as an effective way to mitigate the reliance on petroleum and reduce the greenhouse gas emissions. An increasing demand for second generation biofuels, produced from ligno-cellulosic feedstock and compatible with current infrastructure and vehicle technologies, addresses two major challenges faced by the current US transportation sector: energy security and global warming. However, biofuel production is subject to internal disturbances (feedstock supply and commodity market) and external factors (energy market). The biofuel industry has also heavily relied on government subsidy during the early development stages. In this dissertation, I investigate how to improve the economic and environmental performance of biorefineries (and biofuel plant), as well as enhance its survivability under the external disturbances. Three types of disturbance are considered: (1) energy market fluctuation, (2) subsidy policy uncertainty, and (3) extreme weather conditions. All three factors are basically volatile, dynamic, and even unpredictable, which makes them difficult to model and have been largely ignored to date. Instead, biofuel industry and biofuel research are intensively focused on improving feedstock conversion efficiency and capital cost efficiency while assuming these advancements alone will successfully generate higher profit and thus foster the biofuel industry. The collapse of the largest corn ethanol biofuel company, Verasun Energy, in 2008 calls into question this efficiency-driven approach. A detailed analysis has revealed that although the corn ethanol plants operated by Verasun adopted the more efficient (i.e. higher ethanol yield per bushel of corn and lower capital cost) dry-mill technology, they could not maintain a fair profit margin under fluctuating market condition which made ethanol production unprofitable. This is because dry-mill plant converts a single type of biomass feedstock (corn grain) into a single primary product (ethanol). The traditional lower efficient (i.e. lower ethanol yield per bushel of corn and higher capital cost) wet-mill plant has a more diverse and adjustable product portfolio i.e. corn syrup, starch, and ethanol. The fact that only the dry-mill corn ethanol plants have bankrupted while the wet-mill corn ethanol plants have survived the late 2000s economy recession suggests that the higher conversion efficiency achieved by the dry-mill production mode has jeopardized operational flexibility, a design operational feature I agree that is indispensable for the biofuel plant's long term profit and viability. Based on the analysis of corn ethanol production, operational flexibility has been proposed as a key strategy for the next generation biofuel plants to improve its lifetime economic performance, as well as to enhance its survivability under external disturbances. This strategy requires the biofuel plant to adopt a flexible feedstock management, making it possible to utilize alternative types of biomass feedstock when the primary feedstock supply is disturbed. Biofuel plants also need to produce a wider range of final products that could meet the preference variation that either comes from the energy market or from the subsidy policy. Aspen Plus model based numerical simulations have been carried out for a thermochemical ethanol plant and a Fischer Tropsch plant (both are assumed to be located in southwest Indiana) to test this strategy under the external disturbances of extreme weather impact, different energy price projections and various subsidy policy combinations. For the thermochemical ethanol plant, effects of extreme weather conditions are mainly evaluated. It has been shown that this strategy could effectively increase the net present value of the biofuel plant and significantly decrease the GHG emission comparing with the traditional single-feedstock strategy, when the extreme weather conditions are considered. It has also been demonstrated that this strategy could significantly decrease the possibility for the biofuel plant to bankrupt. For the Fischer Tropsch diesel plant, all the three external disturbances have been examined. It has been learned that operational flexibility through full capacity power co-generation, flexible feedstock management and hydrogen production by natural gas autothermal reforming could maximize the net present value under the influence of the external disturbances. Thus it is suggested that the future biofuel plant should adopt operational flexibility to increase the lifetime economic performance and to enhance the survivability under the influence of external disturbance.

  9. Evaluation and prediction of moisture-induced damage in asphaltic concrete pavements

    SciTech Connect

    Amirkhanian, S.N.

    1987-01-01

    The indirect tensile strength (ITS) test using Tunnicliff and Root moisture conditioning procedures, and boiling test was evaluated to determine the moisture susceptibility of asphaltic concrete specimens. A procedure was developed for inventorying stripping in asphaltic concrete pavements. Cores were obtained from existing pavements and then tested in the laboratory for moisture susceptibility. ITS testing and visual strip ratings were used to evaluate moisture-induced damage in the flexible pavements. Moisture susceptibility of asphaltic concrete mixtures was evaluated in the laboratory using various destructive test methods. A procedure was developed to compare the results of the field-sampling program with the laboratory test results. It was shown, through a laboratory testing procedure, that various asphalt cement sources of the same grade (AC-20), when used with different aggregates and antistrip additives, yielded different ITS values and visual strip ratings. Using the laboratory results, the ACMODAS (Asphalt Concrete Moisture Damage Analysis System) computer program was used to predict consequences of moisture-induced damage in asphaltic concrete mixtures.

  10. Enhanced Piezoelectric Energy Harvesting Performance of Flexible PVDF-TrFE Bilayer Films with Graphene Oxide.

    PubMed

    Bhavanasi, Venkateswarlu; Kumar, Vipin; Parida, Kaushik; Wang, Jiangxin; Lee, Pooi See

    2016-01-13

    Ferroelectric materials have attracted interest in recent years due to their application in energy harvesting owing to its piezoelectric nature. Ferroelectric polymers are flexible and can sustain larger strains compared to inorganic counterparts, making them attractive for harvesting energy from mechanical vibrations. Herein, we report, for the first time, the enhanced piezoelectric energy harvesting performance of the bilayer films of poled poly(vinylidene fluoride-trifluoroethylene) [PVDF-TrFE] and graphene oxide (GO). The bilayer film exhibits superior energy harvesting performance with a voltage output of 4 V and power output of 4.41 μWcm(-2) compared to poled PVDF-TrFE films alone (voltage output of 1.9 V and power output of 1.77 μWcm(-2)). The enhanced voltage and power output in the presence of GO film is due to the combined effect of electrostatic contribution from graphene oxide, residual tensile stress, enhanced Young's modulus of the bilayer films, and the presence of space charge at the interface of the PVDF-TrFE and GO films, arising from the uncompensated polarization of PVDF-TrFE. Higher Young's modulus and dielectric constant of GO led to the efficient transfer of mechanical and electrical energy. PMID:26693844

  11. A Flexible, High Performance Service-Oriented Architecture for Detecting Cyber Attacks

    SciTech Connect

    Wynne, Adam S.; Gorton, Ian; Almquist, Justin P.; Chatterton, Jack; Thurman, David A.

    2008-02-01

    The next generation of intrusion detection and cyber defense technologies must be highly flexible so that deployed solutions can be quickly modified to detect new attack scenarios. They must also be able to provide the performance necessary to monitor traffic from high speed networks, and scale to enterprise wide deployments. In this paper we describe our experiences in creating a production application for cyber situational awareness. The application exploits the capabilities of several independently developed components and integrates them using SIFT (Scalable Information Fusion and Triage), a service-oriented architecture (SOA) designed for creating domain-independent, enterprise scale analytical applications. SIFT exploits a common design pattern for composing analytical components, and extends an existing messaging platform with scaling capabilities. We describe the design of the application, and provide a performance analysis that demonstrates the capabilities of the SIFT platform. The paper concludes by discussing the lessons we have learned from this project, and outlines the architecture of the MeDICI, the next generation of our enterprise analytics platforms.

  12. Lattice Strain Induced Remarkable Enhancement in Piezoelectric Performance of ZnO-Based Flexible Nanogenerators.

    PubMed

    Zhang, Yang; Liu, Caihong; Liu, Jingbin; Xiong, Jie; Liu, Jingyu; Zhang, Ke; Liu, Yudong; Peng, Mingzeng; Yu, Aifang; Zhang, Aihua; Zhang, Yan; Wang, Zhiwei; Zhai, Junyi; Wang, Zhong Lin

    2016-01-20

    In this work, by employing halogen elements (fluorine, chlorine, bromine, and iodine) as dopant we demonstrate a unique strategy to enhance the output performance of ZnO-based flexible piezoelectric nanogenerators. For a halogen-doped ZnO nanowire film, dopants and doping concentration dependent lattice strain along the ZnO c-axis are established and confirmed by the EDS, XRD, and HRTEM analysis. Although lattice strain induced charge separation was theoretically proposed, it has not been experimentally investigated for wurtzite structured ZnO nanomaterials. Tuning the lattice strain from compressive to tensile state along the ZnO c-axis can be achieved by a substitution of halogen dopant from fluorine to other halogen elements due to the ionic size difference between dopants and oxygen. With its focus on a group of nonmetal element induced lattice strain in ZnO-based nanomaterials, this work paves the way for enhancing the performance of wurtzite-type piezoelectric semiconductor nanomaterials via lattice strain strategy which can be employed to construct piezoelectric nanodevices with higher efficiency in a cost-effective manner. PMID:26704902

  13. Replacing Lectures by Text-Based Flexible Learning: Students' Performance and Perceptions.

    ERIC Educational Resources Information Center

    Green, John

    2002-01-01

    Presents the results of an extended evaluation program designed to test the effectiveness of text-based flexible learning as a replacement for 30-50% of the lectures in certain modules in conventional undergraduate courses in the School of Life Sciences at Napier University. Concludes that text-based flexible learning is an effective alternative

  14. Replacing Lectures by Text-Based Flexible Learning: Students' Performance and Perceptions.

    ERIC Educational Resources Information Center

    Green, John

    2002-01-01

    Presents the results of an extended evaluation program designed to test the effectiveness of text-based flexible learning as a replacement for 30-50% of the lectures in certain modules in conventional undergraduate courses in the School of Life Sciences at Napier University. Concludes that text-based flexible learning is an effective alternative…

  15. Hemispherically aggregated BaTiO3 nanoparticle composite thin film for high-performance flexible piezoelectric nanogenerator.

    PubMed

    Shin, Sung-Ho; Kim, Young-Hwan; Lee, Min Hyung; Jung, Joo-Yun; Nah, Junghyo

    2014-03-25

    We report high-performance flexible nanogenerators (NGs) based on a composite thin film, composed of hemispherically aggregated BaTiO3 nanoparticles (NPs) and poly(vinylidene fluoride-co-hexafluoropropene) P(VDF-HFP). The hemispherical BTO-P(VDF-HFP) clusters were realized by a solvent evaporation method, which greatly enhanced piezoelectric power generation. The flexible NGs exhibit high electrical output up to ∼75 V and ∼15 μA at the applied force normal to the surface, indicating the important role of hemispherical BTO clusters. Besides, the durability and reproducibility of the NGs were tested by cyclic measurement under bending stage, generating the output of ∼5 V and ∼750 nA. The approach we introduce here is simple, cost-effective, and well-suited for large-scale high-performance flexible NG fabrication. PMID:24517314

  16. High-Performance Flexible All-Solid-State Supercapacitor from Large Free-Standing Graphene-PEDOT/PSS Films

    NASA Astrophysics Data System (ADS)

    Liu, Yuqing; Weng, Bo; Razal, Joselito M.; Xu, Qun; Zhao, Chen; Hou, Yuyang; Seyedin, Shayan; Jalili, Rouhollah; Wallace, Gordon G.; Chen, Jun

    2015-11-01

    Although great attention has been paid to wearable electronic devices in recent years, flexible lightweight batteries or supercapacitors with high performance are still not readily available due to the limitations of the flexible electrode inventory. In this work, highly flexible, bendable and conductive rGO-PEDOT/PSS films were prepared using a simple bar-coating method. The assembled device using rGO-PEDOT/PSS electrode could be bent and rolled up without any decrease in electrochemical performance. A relatively high areal capacitance of 448 mF cm-2 was achieved at a scan rate of 10 mV s-1 using the composite electrode with a high mass loading (8.49 mg cm-2), indicating the potential to be used in practical applications. To demonstrate this applicability, a roll-up supercapacitor device was constructed, which illustrated the operation of a green LED light for 20 seconds when fully charged.

  17. Anionic polymer electrolyte with enhanced electrochemical performance based on surface-charged latex nanoparticles for flexible lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Ma, Xianguo; Huang, Xinglan; Gao, Jiandong; Zhang, Shu; Peng, Zuling; Deng, Zhenghua; Suo, Jishuan

    2014-12-01

    In the present paper, an anionic polymer electrolyte (APE) is facilely prepared using the surface-charged latex nanoparticles as the building blocks for the flexible lithium-ion batteries. Driven by the self-assembly of surface-charged latex, the APE demonstrates nanoporous structure, which provides continuous pathway for lithium conduction. The anionic polymer membrane exhibits mechanical flexibility before and after swollen with liquid electrolyte. Performance benefits of the anionic polymer membrane, as compared to commercialized polyethylene (PE) separator, are elucidated in terms of thermal shrinkage, liquid electrolyte wettability, mechanical bendability and open circuit voltage (OCV). Based on comprehensive characterization of the anionic polymer membrane/electrolyte characteristics, feasibility of applying the APE to electrolytes for flexible lithium-ion batteries is explored. The well-developed ion-conductive channel of the APE, in conjunction with stability of the surface-charged nanoparticles during cycling, plays a crucial role in providing excellent in cell performance.

  18. Permeable Pavement Research at the Edison Environmental Center

    EPA Science Inventory

    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...

  19. Permeable pavement monitoring at the Edison Environmental Center demonstration site

    EPA Science Inventory

    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...

  20. Permeable pavement demonstration site at Edison Environmental Center (Presentation)

    EPA Science Inventory

    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...

  1. Permeable pavement demonstration at the Edison Environmental Center

    EPA Science Inventory

    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...

  2. Permeable Pavement Demonstration at the Edison Environmental Center (Hartford)

    EPA Science Inventory

    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...

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

    EPA Science Inventory

    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...

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

    ERIC Educational Resources Information Center

    Asphalt Inst., College Park, MD.

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

  5. Permeable Pavement Monitoring at the Edison Environmental Center Demonstration Site

    EPA Science Inventory

    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...

  6. 211. EQUIPMENT LAYING FIRST LANE OF CONCRETE PAVEMENT NEAR THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    211. EQUIPMENT LAYING FIRST LANE OF CONCRETE PAVEMENT NEAR THE CAPITAL OVERLOOK, 1931. NOTE THE BEGINNING OF BITUMINOUS TYPE OF TEMPORARY PAVEMENT TO ALLOW FOR SETTLEMENT IN HYDRAULIC FILL AREAS. - George Washington Memorial Parkway, Along Potomac River from McLean to Mount Vernon, VA, Mount Vernon, Fairfax County, VA

  7. Nutrient Infiltrate Concentrations from Three Permeable Pavement Types

    EPA Science Inventory

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

  8. Optimization of thermoelectric performance in semiconducting polymers for understanding charge transport and flexible thermoelectric applications

    NASA Astrophysics Data System (ADS)

    Glaudell, Anne; Chabinyc, Michael

    2014-03-01

    Organic electronic materials have been widely considered for a variety of energy conversion applications, from photovoltaics to LEDs. Only very recently have organic materials been considered for thermoelectric applications - converting between temperature gradients and electrical potential. The intrinsic disorder in semiconducting polymers leads to an inherently low thermal conductivity, a key parameter in thermoelectric performance. The ability to solution deposit on flexible substrates opens up niche applications including personal cooling and conformal devices. Here work is presented on the electrical conductivity and thermopower of thin film semiconducting polymers, including P3HT and PBTTT-C14. Thermoelectric properties are explored over a wide range of conductivities, from nearly insulating to beyond 100 S/cm, enabled by employing different doping mechanisms, including molecular charge-transfer doping with F4TCNQ and vapor doping with a fluoroalkyl trichlorosilane (FTS). Temperature-dependent measurements suggest competing charge transport mechanisms, likely due to the mixed ordered/disordered character of these polymers. These results show promise for organic materials for thermoelectric applications, and recent results on thin film devices will also be presented.

  9. Highly conductive and flexible polymer composites with improved mechanical and electromagnetic interference shielding performances

    NASA Astrophysics Data System (ADS)

    Chen, Mengting; Zhang, Ling; Duan, Shasha; Jing, Shilong; Jiang, Hao; Luo, Meifang; Li, Chunzhong

    2014-03-01

    New flexible and conductive materials (FCMs) comprising a quartz fiber cloth (QFC) reinforced multi-walled carbon nanotubes (MWCNTs)-carbon aerogel (QMCA) and poly(dimethylsiloxane) (PDMS) have been successfully prepared. The QMCA-PDMS composite with a very low loading of MWCNTs (~1.6 wt%) demonstrates enhanced performance in tensile strength (129.6 MPa), modulus (3.41 GPa) and electromagnetic interference (EMI) shielding efficiency (SE) (~16 dB in X-band (8.2-12.4 GHz) region). Compared to the QC (where MWCNTs were simply deposited on the QFCs without forming aerogel networks) based PDMS composite, a ~120%, 330% and 178% increase of tensile strength, modulus, and EMI SE was obtained, respectively. Moreover, the EMI SE of the QMCA-PDMS composite can further reach 20 dB (a SE level needed for commercial applications) with only 2 wt% MWCNTs. Furthermore, the conductivity of the QMCA-PDMS laminate can reach 1.67 S cm-1 even with very low MWCNTs (1.6 wt%), which still remains constant even after 5000 times bending and exhibits an increase of ~170% than that of MWCNT-carbon aerogel (MCA)-PDMS at 20% strain. Such intriguing performances are mainly attributed to their unique networks in QMCA-PDMS composites. In addition, these features can also protect electronics against harm from external forces and EMI, giving the brand-new FCMs huge potential in next-generation devices, like E-skin, robot joints and so on.New flexible and conductive materials (FCMs) comprising a quartz fiber cloth (QFC) reinforced multi-walled carbon nanotubes (MWCNTs)-carbon aerogel (QMCA) and poly(dimethylsiloxane) (PDMS) have been successfully prepared. The QMCA-PDMS composite with a very low loading of MWCNTs (~1.6 wt%) demonstrates enhanced performance in tensile strength (129.6 MPa), modulus (3.41 GPa) and electromagnetic interference (EMI) shielding efficiency (SE) (~16 dB in X-band (8.2-12.4 GHz) region). Compared to the QC (where MWCNTs were simply deposited on the QFCs without forming aerogel networks) based PDMS composite, a ~120%, 330% and 178% increase of tensile strength, modulus, and EMI SE was obtained, respectively. Moreover, the EMI SE of the QMCA-PDMS composite can further reach 20 dB (a SE level needed for commercial applications) with only 2 wt% MWCNTs. Furthermore, the conductivity of the QMCA-PDMS laminate can reach 1.67 S cm-1 even with very low MWCNTs (1.6 wt%), which still remains constant even after 5000 times bending and exhibits an increase of ~170% than that of MWCNT-carbon aerogel (MCA)-PDMS at 20% strain. Such intriguing performances are mainly attributed to their unique networks in QMCA-PDMS composites. In addition, these features can also protect electronics against harm from external forces and EMI, giving the brand-new FCMs huge potential in next-generation devices, like E-skin, robot joints and so on. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06092f

  10. Monitoring asphalt pavement damages using remote sensing techniques

    NASA Astrophysics Data System (ADS)

    Mettas, Christodoulos; Themistocleous, Kyriacos; Neocleous, Kyriacos; Christofe, Andreas; Pilakoutas, Kypros; Hadjimitsis, Diofantos

    2015-06-01

    One of the main issues in the maintenance plans of road agencies or governmental organizations is the early detection of damaged asphalt pavements. The development of a smart and non-destructive systematic technique for monitoring damaged asphalt pavements is considered a main priority to fill this gap. During the 1970's, remote sensing was used to map road surface distress, while during the last decade, remote sensing became more advanced, thereby assisting in the evolution of the identification and mapping of roads. Various techniques were used in order to explore condition, age, weaknesses and imperfections of asphalted pavements. These methods were fairly successful in the classification of asphalted surfaces and in the detection of some of their characteristics. This paper explores the state of the art of using remote sensing techniques for monitoring damaged pavements and some typical spectral profiles of various asphalt pavements in Cyprus area acquired using the SVC1024 field spectroradiometer.

  11. Airport pavement roughness evaluation based on aircraft response

    NASA Astrophysics Data System (ADS)

    Dong, Qinxi; Hachiya, Yoshitaka; Endo, Katsura; Himeno, Kenji; Kawamura, Akira; Matsui, Kunihito

    2004-07-01

    Runway roughness affects primarily ride quality and dynamic wheel loads. The forces applied onto the airport pavement by aircraft vary instantaneously above and blow the static weight, which in turn increase the runway roughness. One method to effectively assess the ride quality of the airport runway is to measure its longitudinal profile and numerical simulate aircraft response performing a takeoff, landing or taxiing on that profile data. In this study the aircraft responses excited as the aircraft accelerates or moves at a constant speed on the runway during takeoff and taxi are computed by using the improved computer program TAXI. This procedure is capable of taking into account both the effects of discrete runway bumps and runway roughness. Thus, sections of significant dynamic response can be determined, and the maintenance and rehabilitation works for airport runways will be conducted.

  12. Friction evaluation of concrete paver blocks for airport pavement applications

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.

    1992-01-01

    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.

  13. Performance of pre-deformed flexible piezoelectric cantilever in energy harvesting

    NASA Astrophysics Data System (ADS)

    Wang, Pengyingkai; Sui, Li; Shi, Gengchen; Liu, Guohua

    2016-05-01

    This paper proposes a novel structure for pre-rolled flexible piezoelectric cantilevers that use wind energy to power a submunition electrical device. Owing to the particular installation position and working environment, the submunition piezoelectric cantilever should be rolled when not working, but this pre-rolled state can alter the energy harvesting performance. Herein, a working principle and installation method for piezoelectric cantilevers used in submunitions are introduced. To study the influence of the pre-rolled state, pre-rolled piezoelectric cantilevers of different sizes were fabricated and their performances were studied using finite element analysis simulations and experiments. The simulation results show that the resonance frequency and stiffness of the pre-rolled structure is higher than that of a flat structure. Results show that, (1) for both the pre-rolled and flat cantilever, the peak voltage will increase with the wind speed. (2) The pre-rolled cantilever has a higher critical wind speed than the flat cantilever. (3) For identical wind speeds and cantilever sizes, the peak voltage of the flat cantilever (45 V) is less than that of the pre-rolled cantilever (56 V). (4) Using a full-bridge rectifier, the output of the pre-rolled cantilever can sufficiently supply a 10 μF capacitor, whose output voltage may be up to 23 V after 10 s. These results demonstrate that the pre-rolled piezoelectric cantilever and its installation position used in this work are more suitable for submunition, and its output sufficiently meets submunition requirements.

  14. Highly conductive and flexible polymer composites with improved mechanical and electromagnetic interference shielding performances.

    PubMed

    Chen, Mengting; Zhang, Ling; Duan, Shasha; Jing, Shilong; Jiang, Hao; Luo, Meifang; Li, Chunzhong

    2014-04-01

    New flexible and conductive materials (FCMs) comprising a quartz fiber cloth (QFC) reinforced multi-walled carbon nanotubes (MWCNTs)-carbon aerogel (QMCA) and poly(dimethylsiloxane) (PDMS) have been successfully prepared. The QMCA-PDMS composite with a very low loading of MWCNTs (∼1.6 wt%) demonstrates enhanced performance in tensile strength (129.6 MPa), modulus (3.41 GPa) and electromagnetic interference (EMI) shielding efficiency (SE) (∼16 dB in X-band (8.2-12.4 GHz) region). Compared to the QC (where MWCNTs were simply deposited on the QFCs without forming aerogel networks) based PDMS composite, a ∼120%, 330% and 178% increase of tensile strength, modulus, and EMI SE was obtained, respectively. Moreover, the EMI SE of the QMCA-PDMS composite can further reach 20 dB (a SE level needed for commercial applications) with only 2 wt% MWCNTs. Furthermore, the conductivity of the QMCA-PDMS laminate can reach 1.67 S cm(-1) even with very low MWCNTs (1.6 wt%), which still remains constant even after 5000 times bending and exhibits an increase of ∼170% than that of MWCNT-carbon aerogel (MCA)-PDMS at 20% strain. Such intriguing performances are mainly attributed to their unique networks in QMCA-PDMS composites. In addition, these features can also protect electronics against harm from external forces and EMI, giving the brand-new FCMs huge potential in next-generation devices, like E-skin, robot joints and so on. PMID:24577052

  15. Microporous Ni₁₁(HPO₃)₈(OH)₆ nanocrystals for high-performance flexible asymmetric all solid-state supercapacitors.

    PubMed

    Gao, Yanping; Zhao, Junhong; Run, Zhen; Zhang, Guangqin; Pang, Huan

    2014-12-01

    Microporous nickel phosphite [Ni11(HPO3)8(OH)6] nanocrystals were prepared using a hydrothermal method, and were successfully applied as a positive electrode in a flexible all solid-state asymmetric supercapacitor. Because of the specific micro/nanostructure, the flexible solid-state asymmetric supercapacitor can achieve a maximum energy density of 0.45 mW h cm(-3), which is higher than most reported supercapacitors. More importantly, the device performance remains efficient for 10,000 cycles. PMID:25329036

  16. Tire Footprint Affects Hydroplaning On Wet Pavement

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.

    1989-01-01

    Recent investigations of tire hydroplaning at highway speeds reveal, in addition to inflation pressure, tire-footprint aspect ratio (FAR), defined as width divided by length of tire surface in contact with pavement, significantly influences speed at which dynamic hydroplaning begins. Tire speeds and forces developed during tests of up to 65 mi/h (105 km/h) were monitored on flooded test surface to identify development of hydroplaning. Study focused on automotive tires because FAR's of automotive tires vary more than those of aircraft tires.

  17. Evaluating and improving mechanical performance of thin films for flexible displays

    NASA Astrophysics Data System (ADS)

    Lewis, Jay S.; Grego, Sonia; Vick, Erik; Temple, Dorota

    2005-05-01

    Organic light emitting diode (OLED) based displays are well suited for fabrication on flexible polymer substrates. In order to achieve the vision of a highly flexible, rollable display, significant progress must be made in understanding and overcoming the mechanical limitations of the component materials. Methodologies and metrics for evaluating thin film components as well as full devices on flexible substrates need to be developed and standardized. A new technique for bend testing is described here and compared to a more traditional technique. One thin film component of flexible OLEDs that must be very mechanically robust is the permeation barrier. It is desirable to have a rapid method to characterize the onset of cracking upon bending of a barrier-coated substrate. We have developed a convenient method that allows characterization of mechanical cracking of flexible permeation barriers. In addition, transparent conductors with mechanical properties superior to those of ITO are desired for improved flexibility of displays. We report dramatically improved mechanical properties of multilayer ITO-Ag-ITO films that also exhibit excellent electrical and optical properties. Finally, we show preliminary results from bend tests of complete OLED devices on polymer substrates. The results demonstrate that in addition to evaluating component materials, other factors must be considered for integrated devices, and further investigation on this subject is needed.

  18. A high-performance, flexible and robust metal nanotrough-embedded transparent conducting film for wearable touch screen panels.

    PubMed

    Im, Hyeon-Gyun; An, Byeong Wan; Jin, Jungho; Jang, Junho; Park, Young-Geun; Park, Jang-Ung; Bae, Byeong-Soo

    2016-02-11

    We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband. PMID:26866678

  19. Roll-to-Roll Encapsulation of Metal Nanowires between Graphene and Plastic Substrate for High-Performance Flexible Transparent Electrodes.

    PubMed

    Deng, Bing; Hsu, Po-Chun; Chen, Guanchu; Chandrashekar, B N; Liao, Lei; Ayitimuda, Zhawulie; Wu, Jinxiong; Guo, Yunfan; Lin, Li; Zhou, Yu; Aisijiang, Mahaya; Xie, Qin; Cui, Yi; Liu, Zhongfan; Peng, Hailin

    2015-06-10

    Transparent conductive film on plastic substrate is a critical component in low-cost, flexible, and lightweight optoelectronics. Industrial-scale manufacturing of high-performance transparent conductive flexible plastic is needed to enable wide-ranging applications. Here, we demonstrate a continuous roll-to-roll (R2R) production of transparent conductive flexible plastic based on a metal nanowire network fully encapsulated between graphene monolayer and plastic substrate. Large-area graphene film grown on Cu foil via a R2R chemical vapor deposition process was hot-laminated onto nanowires precoated EVA/PET film, followed by a R2R electrochemical delamination that preserves the Cu foil for reuse. The encapsulated structure minimized the resistance of both wire-to-wire junctions and graphene grain boundaries and strengthened adhesion of nanowires and graphene to plastic substrate, resulting in superior optoelectronic properties (sheet resistance of ∼8 Ω sq(-1) at 94% transmittance), remarkable corrosion resistance, and excellent mechanical flexibility. With these advantages, long-cycle life flexible electrochromic devices are demonstrated, showing up to 10000 cycles. PMID:26020567

  20. Effect of TiO2 Particle Size on the Performance of Flexible Dye Sensitized Solar Cells.

    PubMed

    Li, Zhen-yu; Akhtar, M Shaheer; Yang, O-bong

    2015-09-01

    The size TiO2 nanoparticles was controlled by changing the concentration of titanium tetraisopropanolate (TTIP) and utilized as light scattering particles in the efficient flexible photoelectrodes for flexible dye sensitized solar cells (DSSCs). The flexible photoelectrodes were prepared by TiO2 nanoparticles (-25 nm) paste with different concentrations of ethanolic TTIP solution. The addition of TTIP produced the bigger TiO2 nanoparticles, which significantly enhanced the dye absorption of flexible TiO2 photoelectrode. The fabricated flexible DSSCs showed the reasonable conversion efficiency of 2.50% with short circuit current (J(sc)) of 6.3 mA/cm2, open circuit voltage (V(oc)) of 0.720 V and fill factor (FF) of 0.55. The improvement in photovoltaic performance with 25 wt% TTIP might due to uniform distribution of small TiO2 nanoparticles over the big particles to lead the enhancement in the surface area, resulting in the high dye absorption and light harvesting efficiency. PMID:26716227

  1. Highly Flexible Freestanding Porous Carbon Nanofibers for Electrodes Materials of High-Performance All-Carbon Supercapacitors.

    PubMed

    Liu, Ying; Zhou, Jinyuan; Chen, Lulu; Zhang, Peng; Fu, Wenbin; Zhao, Hao; Ma, Yufang; Pan, Xiaojun; Zhang, Zhenxing; Han, Weihua; Xie, Erqing

    2015-10-28

    Highly flexible porous carbon nanofibers (P-CNFs) were fabricated by electrospining technique combining with metal ion-assistant acid corrosion process. The resultant fibers display high conductivity and outstanding mechanical flexibility, whereas little change in their resistance can be observed under repeatedly bending, even to 180°. Further results indicate that the improved flexibility of P-CNFs can be due to the high graphitization degree caused by Co ions. In view of electrode materials for high-performance supercapacitors, this type of porous nanostructure and high graphitization degree could synergistically facilitate the electrolyte ion diffusion and electron transportation. In the three electrodes testing system, the resultant P-CNFs electrodes can exhibit a specific capacitance of 104.5 F g(-1) (0.2 A g(-1)), high rate capability (remain 56.5% at 10 A g(-1)), and capacitance retention of ∼94% after 2000 cycles. Furthermore, the assembled symmetric supercapacitors showed a high flexibility and can deliver an energy density of 3.22 Wh kg(-1) at power density of 600 W kg(-1). This work might open a way to improve the mechanical properties of carbon fibers and suggests that this type of freestanding P-CNFs be used as effective electrode materials for flexible all-carbon supercapacitors. PMID:26449440

  2. A high-performance, flexible and robust metal nanotrough-embedded transparent conducting film for wearable touch screen panels

    NASA Astrophysics Data System (ADS)

    Im, Hyeon-Gyun; An, Byeong Wan; Jin, Jungho; Jang, Junho; Park, Young-Geun; Park, Jang-Ung; Bae, Byeong-Soo

    2016-02-01

    We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband.We report a high-performance, flexible and robust metal nanotrough-embedded transparent conducting hybrid film (metal nanotrough-GFRHybrimer). Using an electro-spun polymer nanofiber web as a template and vacuum-deposited gold as a conductor, a junction resistance-free continuous metal nanotrough network is formed. Subsequently, the metal nanotrough is embedded on the surface of a glass-fabric reinforced composite substrate (GFRHybrimer). The monolithic composite structure of our transparent conducting film allows simultaneously high thermal stability (24 h at 250 °C in air), a smooth surface topography (Rrms < 1 nm) and excellent opto-electrical properties. A flexible touch screen panel (TSP) is fabricated using the transparent conducting films. The flexible TSP device stably operates on the back of a human hand and on a wristband. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07657a

  3. A Comparison of Masticatory Performance and Efficiency of Complete Dentures Made with High Impact and Flexible Resins: A Pilot Study

    PubMed Central

    Bhoyar, Anjali; Mishra, Sunil Kumar; Yadav, Naveen S.; Mahajan, Harsh

    2015-01-01

    Background In patients with extensive tooth loss, restoration of masticatory function and aesthetics is main concern for a prosthodontist. Aim of Study This study aimed to evaluate and compare differences in masticatory efficiency of patients treated with complete dentures made with either high impact or flexible resins. Setting and Design The sample size consisted of 10 study subjects. Two sets of dentures first conventional followed by flexible dentures were fabricated for each subject and both the sets of dentures were accessed for masticatory performance and efficiency. Materials and Methods This study compared the masticatory performance and efficiency of dentures by means of standardized mesh sieves. Masticatory efficiency was calculated by recording the total number of chewing cycles and time required to completely swallow a standardized food item. A patient satisfaction questionnaire was given and evaluated. Statistical Analysis Used The statistical analyses were performed using Z-test of Proportion and Paired t-test. Results The masticatory performance ratio was found to be more for hard food in conventional dentures. The values of masticatory performance ratios for soft food, time and number of masticatory strokes were indicating better masticatory efficiency of conventional dentures. Conclusion Though masticatory efficiency and performance were found to be better for patient’s dentures made with Polymethyl methacrylate (PMMA), a statistically significant number of patients reported that the flexible dentures were more satisfying than the conventional dentures. PMID:26266213

  4. Characterizing a porous road pavement using surface impedance measurement: a guided numerical inversion procedure.

    PubMed

    Benoit, Gaëlle; Heinkélé, Christophe; Gourdon, Emmanuel

    2013-12-01

    This paper deals with a numerical procedure to identify the acoustical parameters of road pavement from surface impedance measurements. This procedure comprises three steps. First, a suitable equivalent fluid model for the acoustical properties porous media is chosen, the variation ranges for the model parameters are set, and a sensitivity analysis for this model is performed. Second, this model is used in the parameter inversion process, which is performed with simulated annealing in a selected frequency range. Third, the sensitivity analysis and inversion process are repeated to estimate each parameter in turn. This approach is tested on data obtained for porous bituminous concrete and using the Zwikker and Kosten equivalent fluid model. This work provides a good foundation for the development of non-destructive in situ methods for the acoustical characterization of road pavements. PMID:25669290

  5. Adaptive Road Crack Detection System by Pavement Classification

    PubMed Central

    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

    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

  6. Conjunction of Conducting Polymer Nanostructures with Macroporous Structured Graphene Thin Films for High-Performance Flexible Supercapacitors.

    PubMed

    Memon, Mushtaque A; Bai, Wei; Sun, Jinhua; Imran, Muhammad; Phulpoto, Shah Nawaz; Yan, Shouke; Huang, Yong; Geng, Jianxin

    2016-05-11

    Fabrication of hybridized structures is an effective strategy to promote the performances of graphene-based composites for energy storage/conversion applications. In this work, macroporous structured graphene thin films (MGTFs) are fabricated on various substrates including flexible graphene papers (GPs) through an ice-crystal-induced phase separation process. The MGTFs prepared on GPs (MGTF@GPs) are recognized with remarkable features such as interconnected macroporous configuration, sufficient exfoliation of the conductive RGO sheets, and good mechanical flexibility. As such, the flexible MGTF@GPs are demonstrated as a versatile conductive platform for depositing conducting polymers (CPs), e.g., polyaniline (PAn), polypyrrole, and polythiophene, through in situ electropolymerization. The contents of the CPs in the composite films are readily controlled by varying the electropolymerization time. Notably, electrodeposition of PAn leads to the formation of nanostructures of PAn nanofibers on the walls of the macroporous structured RGO framework (PAn@MGTF@GPs): thereafter, the PAn@MGTF@GPs display a unique structural feature that combine the nanostructures of PAn nanofibers and the macroporous structures of RGO sheets. Being used as binder-free electrodes for flexible supercapacitors, the PAn@MGTF@GPs exhibit excellent electrochemical performance, in particular a high areal specific capacity (538 mF cm(-2)), high cycling stability, and remarkable capacitive stability to deformation, due to the unique electrode structures. PMID:27110720

  7. Inkjet printing of flexible high-performance carbon nanotube transparent conductive films by ``coffee ring effect''

    NASA Astrophysics Data System (ADS)

    Shimoni, Allon; Azoubel, Suzanna; Magdassi, Shlomo

    2014-09-01

    Transparent and flexible conductors are a major component in many modern optoelectronic devices, such as touch screens for smart phones, displays, and solar cells. Carbon nanotubes (CNTs) offer a good alternative to commonly used conductive materials, such as metal oxides (e.g. ITO) for flexible electronics. The production of transparent conductive patterns, and arrays composed of connected CNT ``coffee rings'' on a flexible substrate poly(ethylene terephthalate), has been reported. Direct patterning is achieved by inkjet printing of an aqueous dispersion of CNTs, which self-assemble at the rim of evaporating droplets. After post-printing treatment with hot nitric acid, the obtained TCFs are characterized by a sheet resistance of 156 Ω sq-1 and transparency of 81% (at 600 nm), which are the best reported values obtained by inkjet printing of conductive CNTs. This makes such films very promising as transparent conductors for various electronic devices, as demonstrated by using an electroluminescent device.

  8. Inkjet printing of flexible high-performance carbon nanotube transparent conductive films by "coffee ring effect".

    PubMed

    Shimoni, Allon; Azoubel, Suzanna; Magdassi, Shlomo

    2014-10-01

    Transparent and flexible conductors are a major component in many modern optoelectronic devices, such as touch screens for smart phones, displays, and solar cells. Carbon nanotubes (CNTs) offer a good alternative to commonly used conductive materials, such as metal oxides (e.g. ITO) for flexible electronics. The production of transparent conductive patterns, and arrays composed of connected CNT "coffee rings" on a flexible substrate poly(ethylene terephthalate), has been reported. Direct patterning is achieved by inkjet printing of an aqueous dispersion of CNTs, which self-assemble at the rim of evaporating droplets. After post-printing treatment with hot nitric acid, the obtained TCFs are characterized by a sheet resistance of 156 Ω sq(-1) and transparency of 81% (at 600 nm), which are the best reported values obtained by inkjet printing of conductive CNTs. This makes such films very promising as transparent conductors for various electronic devices, as demonstrated by using an electroluminescent device. PMID:25014193

  9. Clogging evaluation of open graded friction course pavements tested under rainfall and heavy vehicle simulators.

    PubMed

    Coleri, Erdem; Kayhanian, Masoud; Harvey, John T; Yang, Kai; Boone, John M

    2013-11-15

    In this study a new procedure is developed to obtain core samples from field sections to assess clogging mechanisms of open graded friction course (OGFC) pavements using X-ray computed tomography (CT) imaging. The approach compared X-ray computed tomography (CT) images taken before and after: (1) rainfall simulations without trafficking to investigate particle-related clogging and (2) full-scale accelerated pavement rutting tests (APT) to investigate deformation related clogging of OGFC layers. Rainfall simulations were performed with runoff water of known total suspended solids (TSS) and particle size distributions (PSDs). Full-scale accelerated rutting tests were performed under controlled temperature and loads. Both investigations were performed for three different OGFC pavements with different layer thicknesses and mix types. The clogging of rutting test sections were also evaluated by comparing the surface permeability measurements performed before and after APT testing. The results of X-ray CT image processing revealed a significant reduction in air-void content of core samples after APT rutting tests. The highest air-void reduction was concentrated at the bottom of the OGFC layers. Permeability measurements also showed a 40%-90% reduction in permeability after APT trafficking. X-ray CT image processing of core samples tested under simulated rainfall showed that air void content reduction is concentrated in the lower part (2-6 mm from the bottom) of the OGFC layers as a result of particle accumulation. Small changes in air void contents were observed in the upper part of the OGFC layers (10-15 mm) while these reductions in air void contents were not significant to cause surface overflow and hence it is expected that the tested OGFC pavements will have sufficient permeability to infiltrate water during most average storm events. PMID:23920417

  10. Pavement cracking measurements using 3D laser-scan images

    NASA Astrophysics Data System (ADS)

    Ouyang, W.; Xu, B.

    2013-10-01

    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.

  11. Transparent and flexible high-performance supercapacitors based on single-walled carbon nanotube films

    NASA Astrophysics Data System (ADS)

    Kanninen, Petri; Dang Luong, Nguyen; Hoang Sinh, Le; Anoshkin, Ilya V.; Tsapenko, Alexey; Seppälä, Jukka; Nasibulin, Albert G.; Kallio, Tanja

    2016-06-01

    Transparent and flexible energy storage devices have garnered great interest due to their suitability for display, sensor and photovoltaic applications. In this paper, we report the application of aerosol synthesized and dry deposited single-walled carbon nanotube (SWCNT) thin films as electrodes for an electrochemical double-layer capacitor (EDLC). SWCNT films exhibit extremely large specific capacitance (178 F g‑1 or 552 μF cm‑2), high optical transparency (92%) and stability for 10 000 charge/discharge cycles. A transparent and flexible EDLC prototype is constructed with a polyethylene casing and a gel electrolyte.

  12. High-performance flexible hydrogen sensor made of WS2 nanosheet-Pd nanoparticle composite film.

    PubMed

    Kuru, Cihan; Choi, Duyoung; Kargar, Alireza; Liu, Chin Hung; Yavuz, Serdar; Choi, Chulmin; Jin, Sungho; Bandaru, Prabhakar R

    2016-05-13

    We report a flexible hydrogen sensor, composed of WS2 nanosheet-Pd nanoparticle composite film, fabricated on a flexible polyimide substrate. The sensor offers the advantages of light-weight, mechanical durability, room temperature operation, and high sensitivity. The WS2-Pd composite film exhibits sensitivity (R 1/R 2, the ratio of the initial resistance to final resistance of the sensor) of 7.8 to 50 000 ppm hydrogen. Moreover, the WS2-Pd composite film distinctly outperforms the graphene-Pd composite, whose sensitivity is only 1.14. Furthermore, the ease of fabrication holds great potential for scalable and low-cost manufacturing of hydrogen sensors. PMID:27040653

  13. Transparent and flexible high-performance supercapacitors based on single-walled carbon nanotube films.

    PubMed

    Kanninen, Petri; Luong, Nguyen Dang; Sinh, Le Hoang; Anoshkin, Ilya V; Tsapenko, Alexey; Seppälä, Jukka; Nasibulin, Albert G; Kallio, Tanja

    2016-06-10

    Transparent and flexible energy storage devices have garnered great interest due to their suitability for display, sensor and photovoltaic applications. In this paper, we report the application of aerosol synthesized and dry deposited single-walled carbon nanotube (SWCNT) thin films as electrodes for an electrochemical double-layer capacitor (EDLC). SWCNT films exhibit extremely large specific capacitance (178 F g(-1) or 552 μF cm(-2)), high optical transparency (92%) and stability for 10 000 charge/discharge cycles. A transparent and flexible EDLC prototype is constructed with a polyethylene casing and a gel electrolyte. PMID:27122323

  14. Research on pavement roughness based on the laser triangulation

    NASA Astrophysics Data System (ADS)

    Chen, Wenxue; Ni, Zhibin; Hu, Xinhan; Lu, Xiaofeng

    2016-03-01

    Pavement roughness is one of the most important factors for appraising highway construction. In this paper, we choose the laser triangulation to measure pavement roughness. The principle and configuration of laser triangulation are introduced. Based on this technology, the pavement roughness of a road surface is measured. The measurement results are given in this paper. The measurement range of this system is 50 μm. The measurement error of this technology is analyzed. This technology has an important significance to appraise the quality of highway after completion of the workload.

  15. Effectiveness of low impact development practices in two urbanized watersheds: retrofitting with rain barrel/cistern and porous pavement.

    PubMed

    Ahiablame, Laurent M; Engel, Bernard A; Chaubey, Indrajeet

    2013-04-15

    The impacts of urbanization on hydrology and water quality can be minimized with the use of low impact development (LID) practices in urban areas. This study assessed the performance of rain barrel/cistern and porous pavement as retrofitting technologies in two urbanized watersheds of 70 and 40 km(2) near Indianapolis, Indiana. Six scenarios consisting of the watershed existing condition, 25% and 50% implementation of rain barrel/cistern and porous pavement, and 25% rain barrel/cistern combined with 25% porous pavement were evaluated using a proposed LID modeling framework and the Long-Term Hydrologic Impact Assessment (L-THIA)-LID model. The model was calibrated for annual runoff from 1991 to 2000, and validated from 2001 to 2010 for the two watersheds. For the calibration period, R(2) and NSE values were greater than 0.60 and 0.50 for annual runoff and streamflow. Baseflow was not calibrated in this study. During the validation period, R(2) and NSE values were greater than 0.50 for runoff and streamflow, and 0.30 for baseflow in the two watersheds. The various application levels of barrel/cistern and porous pavement resulted in 2-12% reduction in runoff and pollutant loads for the two watersheds. Baseflow loads slightly increased with increase in baseflow by more than 1%. However, reduction in runoff led to reduction in total streamflow and associated pollutant loads by 1-9% in the watersheds. The results also indicate that the application of 50% rain barrel/cistern, 50% porous pavement and 25% rain barrel/cistern combined with 25% porous pavement are good retrofitting options in these watersheds. The L-THIA-LID model can be used to inform management and decision-making for implementation of LID practices at the watershed scale. PMID:23474339

  16. Flexible SnO(2) hollow nanosphere film based high-performance ultraviolet photodetector.

    PubMed

    Tian, Wei; Zhang, Chao; Zhai, Tianyou; Li, Song-Lin; Wang, Xi; Liao, Meiyong; Tsukagoshi, Kazuhito; Golberg, Dmitri; Bando, Yoshio

    2013-05-01

    A high-quality SnO(2) hollow-sphere nanofilm based flexible photodetector was constructed via'water-oil' interfacial assembling. The photodetector showed high sensitivity, superb stability, and was also able to bear significant external mechanical forces. PMID:23396397

  17. Use of shredded tires in the subbase layer of asphalt pavements

    SciTech Connect

    Papp, W.J. Jr.; Maher, M.H.; Baker, R.F.

    1997-12-31

    Research was conducted on the use of shredded scrap tires for use in the subbase layer of asphalt pavements. Mixtures of shredded scrap tires with virgin soil provide a means of recycling unwanted tires and conserving a finite supply of virgin soil. The mechanistic procedure for the design of pavement systems requires resilient modulus values. Plastic and elastic strains were measured using external LVDT`s and internal proximity sensors. Resilient modulus measurements were conducted on cohesionless soils mixed with various amounts of shredded tire chips. The performance f the shredded tire mixture is compared to that of the naturally occurring virgin soil used in subbase applications in New Jersey. A number of experimental issues are discussed such as: method of compaction, optimum ratio of shredded tire chips to soil, optimum size and gradation of shredded tire chips, and strength testing using California Bearing Ratio.

  18. Recycling crumb rubber modified asphalt pavements (revised). Final research report, September 1992-August 1994

    SciTech Connect

    Crockford, W.W.; Makunike, D.; Davison, R.R.; Scullion, T.; Billiter, T.C.

    1995-07-01

    There has been concern that the legislative mandate to use waste rubber in paving applications will result in a severe environmental problem when it becomes necessary to recycle these pavements. If successful recycling is possible, the long term performance of these pavements becomes a concern. The results of this study indicate that it is possible to recycle this material. However, some techniques for conventional asphalt mixture design, material processing, and construction must be modified to ensure this success, and some techniques may not be appropriate when waste rubber is present in the mixture to be recycled. Many of the results presented in this study are based on experiences in Tyler and San Antonio, Texas, where two of the earliest crumb rubber recycling operations in the United States have transpired.

  19. A review on using crumb rubber in reinforcement of asphalt pavement.

    PubMed

    Mashaan, Nuha Salim; Ali, Asim Hassan; Karim, Mohamed Rehan; Abdelaziz, Mahrez

    2014-01-01

    An immense problem affecting environmental pollution is the increase of waste tyre vehicles. In an attempt to decrease the magnitude of this issue, crumb rubber modifier (CRM) obtained from waste tyre rubber has gained interest in asphalt reinforcement. The use of crumb rubber in the reinforcement of asphalt is considered as a smart solution for sustainable development by reusing waste materials, and it is believed that crumb rubber modifier (CRM) could be an alternative polymer material in improving hot mix asphalt performance properties. In this paper, a critical review on the use of crumb rubber in reinforcement of asphalt pavement will be presented and discussed. It will also include a review on the effects of CRM on the stiffness, rutting, and fatigue resistance of road pavement construction. PMID:24688369

  20. A Review on Using Crumb Rubber in Reinforcement of Asphalt Pavement

    PubMed Central

    Mashaan, Nuha Salim; Ali, Asim Hassan; Karim, Mohamed Rehan; Abdelaziz, Mahrez

    2014-01-01

    An immense problem affecting environmental pollution is the increase of waste tyre vehicles. In an attempt to decrease the magnitude of this issue, crumb rubber modifier (CRM) obtained from waste tyre rubber has gained interest in asphalt reinforcement. The use of crumb rubber in the reinforcement of asphalt is considered as a smart solution for sustainable development by reusing waste materials, and it is believed that crumb rubber modifier (CRM) could be an alternative polymer material in improving hot mix asphalt performance properties. In this paper, a critical review on the use of crumb rubber in reinforcement of asphalt pavement will be presented and discussed. It will also include a review on the effects of CRM on the stiffness, rutting, and fatigue resistance of road pavement construction. PMID:24688369

  1. On performance of an oscillating plate underwater propulsion system with variable chordwise flexibility at different depths of submergence

    NASA Astrophysics Data System (ADS)

    Barannyk, Oleksandr; Buckham, Bradley J.; Oshkai, Peter

    2012-01-01

    In this work, an oscillating plate propulsor undergoing a combination of heave translation and pitch rotation is investigated experimentally. The oscillation kinematics are inspired by swimming mechanisms employed by fish and other marine animals. The primary focus was on the propulsive characteristics of such oscillating plates, which were studied by means of direct force measurements in the thrust-producing regime. Experiments were performed at constant Reynolds number and constant heave amplitude. By varying the Strouhal number, the depth of submergence and the chordwise flexibility of the plate, it was possible to investigate corresponding changes in the generated thrust and the hydromechanical efficiency. It was possible to establish a set of parameters, including the driving frequency of the system, the ratio of rigid to flexible segment length of the plate, and the range of Strouhal numbers that led to an overall increase in thrust and efficiency. The experiments, involving plates with various ratios of rigid to flexible segment lengths, showed that greater flexibility increased the propulsive efficiency and thrust compared to an identical motion of the purely rigid plate. By submerging the plate at different depths, it was observed that the proximity of the propulsor to the bottom of the channel led to an overall increase in the thrust coefficient across the oscillation frequencies considered. The flow visualization revealed the formation of large dynamic stall vortices that influenced the wake structure, and suggested that their constructive interaction with trailing edge vortices might lead to overall improvement of thrust and efficiency.

  2. Joint application of GPR and electrostatic resistivity to assess mixed pavement condition

    NASA Astrophysics Data System (ADS)

    Chouteau, M.; Camerlynck, C.; Kaouane, C.

    2009-05-01

    In planning maintenance and rehabilitation of paved streets it is of first importance to gather internal structure information to establish a diagnostic. We investigate the potential of the GPR and of the capacitively-coupled resistivity array profiling techniques to map the geometry and the defects present at various depths in streets with mixed pavement. GPR is excellent at delineating boundaries of material with contrasting electrical properties whereas the resistivity array is needed to determine the nature and quality of the imaged material. Thicknesses of asphalt and concrete can be continuously determined. Defects such as cracks, delaminations, voids and former repairs can be mapped. Quality of the concrete slab can be assessed by resistivity. The performances of the two techniques are demonstrated first using numerical modeling and imaging of typical pavement defects. Resistivity and GPR data were collected along a few streets in Montreal using a 1GHz GPR smart cart and a compact 2-receiver dipole resistivity system. Streets were selected to demonstrate the responses to different pavement defects. The results allow to show the performance and limitations of present systems. In particular, it is shown that multiple configuration arrays and real-time imaging for the resistivity pulled array are needed. For the arrays we investigate some designs and for the real-time imaging a technique based on Kalman filtering was developed.

  3. High-performance flexible hydrogen sensor made of WS2 nanosheet–Pd nanoparticle composite film

    NASA Astrophysics Data System (ADS)

    Kuru, Cihan; Choi, Duyoung; Kargar, Alireza; Liu, Chin Hung; Yavuz, Serdar; Choi, Chulmin; Jin, Sungho; Bandaru, Prabhakar R.

    2016-05-01

    We report a flexible hydrogen sensor, composed of WS2 nanosheet–Pd nanoparticle composite film, fabricated on a flexible polyimide substrate. The sensor offers the advantages of light-weight, mechanical durability, room temperature operation, and high sensitivity. The WS2–Pd composite film exhibits sensitivity (R 1/R 2, the ratio of the initial resistance to final resistance of the sensor) of 7.8 to 50 000 ppm hydrogen. Moreover, the WS2–Pd composite film distinctly outperforms the graphene–Pd composite, whose sensitivity is only 1.14. Furthermore, the ease of fabrication holds great potential for scalable and low-cost manufacturing of hydrogen sensors.

  4. Influence of a front buffer layer on the performance of flexible Cadmium sulfide/Cadmium telluride solar cells

    NASA Astrophysics Data System (ADS)

    Mahabaduge, Hasitha Padmika

    Cadmium telluride (CdTe) solar cells have been developing as a promising candidate for large-scale application of photovoltaic energy conversion and have become the most commercially successful polycrystalline thin-film solar module material. In scaling up from small cells to large-area modules, inevitably non-uniformities across the large area will limit the performance of the large cell or module. The effects of these non-uniformities can be reduced by introducing a thin, high-resistivity transparent buffer layer between the conductive electrodes and the semiconductor diode. ZnO is explored in this dissertation as a high-resistivity transparent buffer layer for sputtered CdTe solar cells and efficiencies over 15% have been achieved on commercially available Pilkington TEC15M glass substrates. The highest open-circuit voltage of 0.858V achieved using the optimized ZnO buffer layer is among the best reported in the literature. The properties of ZnO:Al as a buffer are also investigated. We have shown that ZnO:Al can serve both as a transparent conducting oxide layer as well as a high-resistivity transparent layer for CdTe solar cells. ZnO:Al reactively sputtered with oxygen can give the necessary resistivities that allow it to be used as a high-resistivity transparent layer. Glass is the most common choice as the substrate for solar cells fabricated in the superstrate configuration due to its transparency and mechanical rigidity. However flexible substrates offer the advantages of light weight, high flexibility, ease of integrability and higher throughput through roll-to-roll processing over glass. This dissertation presents significant improvements made to flexible CdTe solar cells reporting an efficiency of 14% on clear KaptonRTM flexible polyimide substrates. Our efficiency of 14% is, to our knowledge, the best for any flexible CdTe cell reported in literature.

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

    NASA Astrophysics Data System (ADS)

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

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

  6. Permeable Pavement Demonstration at the Edison Environmental Center - Poster

    EPA Science Inventory

    Poster for the SAB Review detailing the porous pavement parking lot project. The poster describes the design of the parking lot, the research components that were incorporated into the design, and the monitoring plan.

  7. Impact of magnetic isolation on pointing system performance in the presence of structural flexibility

    NASA Technical Reports Server (NTRS)

    Seller, J.

    1985-01-01

    The inertial pointing stability of a gimbal pointing system (AGS) was compared with a magnetic pointing/gimbal followup system (ASPS), under certain conditions of system structural flexibility and disturbance inputs from the gimbal support structure. Separate 3 degree-of-freedom (3DOF) linear models based on NASTRAN modal flexibility data for the gimbal and support structures were generated for the ASPS configurations. Using the models inertial pointing control loops providing 6dB of gain margin and 45 deg of phase margin were defined for each configuration. The pointing loop bandwidth obtained for the ASPS is more than twice the level achieved for the AGS configuration. The AGS limit is attributed to the gimbal and support structure flexibility. As a result of the higher ASPS pointing loop bandwidth and the disturbance rejection provided by the magnetic isolation ASPS pointing performane is significantly better than that of the AGS system. The low frequency peak of the ASPS transfer function from base disturbance to payload angular motion is almost 60dB lower than AGS low frequency peak.

  8. Characterization of cementitiously stabilized subgrades for mechanistic-empirical pavement design

    NASA Astrophysics Data System (ADS)

    Solanki, Pranshoo

    Pavements are vulnerable to subgrade layer performance because it acts as a foundation. Due to increase in the truck traffic, pavement engineers are challenged to build more strong and long-lasting pavements. To increase the load-bearing capacity of pavements, subgrade layer is often stabilized with cementitious additives. Thus, an overall characterization of stabilized subgrade layer is important for enhanced short- and long-term pavement performance. In this study, the effect of type and amount of additive on the short-term performance in terms of material properties recommended by the new Mechanistic-Empirical Pavement Design Guide (MEPDG) is examined. A total of four soils commonly encountered as subgrades in Oklahoma are utilized. Results show that the changes in the Mr, ME and UCS values stabilized specimens depend on the soil type and properties of additives. The long-term performance (or durability) of stabilized soil specimens is investigated by conducting freeze-thaw (F-T) cycling, vacuum saturation and tube suction tests on 7-day cured P-, K- and C-soil specimens stabilized with 6% lime, 10% CFA and 10% CKD. This study is motivated by the fact that during the service life of pavement stabilized layers are subjected to F-T cycles and moisture variations. It is found that that UCS value of all the stabilized specimens decreased with increase in the number of F-T cycles. A strong correlation was observed between UCS values retained after vacuum saturation and F-T cycles indicating that vacuum saturation could be used as a time-efficient and inexpensive method for evaluating durability of stabilized soils. In this study, short- and long-term observations from stabilization of sulfate bearing soil with locally available low (CFA), moderate (CKD) and high (lime) calcium-based stabilizers are determined to evaluate and compare the effect of additive type on the phenomenon of sulfate-induced heave. The impact of different factors on the development of the ettringite, responsible for sulfate-induced heaving, is also discussed. For Level 2 design of pavements, a total of four stress-based statistical models and two feed-forward-type artificial neural network (ANN) models, are evaluated for predicting resilient modulus of 28-day cured stabilized specimens. Specifically, one semi-log stress-based, three log-log stress-based, one Multi-Layer Perceptrons Network (MLPN), and one Radial Basis Function Network (RBFN) are developed. Overall, semi-log stress-based and MLPN neural network are found to show best acceptable performance for the present evaluation and validation datasets. Further, correlations are presented for stress-based models to correlate Mr with compacted specimen characteristics and soil/additive properties. Additionally, the effect of type of additive on indirect tensile and fatigue characteristics of selected stabilized P- and V-soil is evaluated. This study is based on the fact that stabilized layer is subjected to tensile stresses under wheel loading. Thus, the resilient modulus in tension (M rt), fatigue life and strength in tension (sigmat) or flexure (represented by modulus of rupture, MOR) becomes another important design parameter within the mechanistic framework. Cylindrical specimens are prepared, cured for 28 days and subjected to different stress sequences in indirect tension to study the Mrt. On the other hand, stabilized beam specimens are compacted using a Linear Kneading Compactor and subjected to repeated cycles of reloading-unloading after 28 days of curing in a four-point beam fatigue apparatus for evaluating fatigue life and flexural stiffness. It is found that all three additives improved the Mrt, sigmat and MOR values; however, degree of improvement varied with the type of additive and soil. This study encompasses the differences in the design of semi-rigid pavements developed using AASHTO 1993 and AASHTO 2002 MEPDG methodologies. Further, the design curves for fatigue performance prediction of stabilized layers are developed for different stabilized pavement sections. Knowledge gained from the parametric analysis of different sections using AASHTO 1993 and MEPDG is expected to be useful to pavement designers and others in implementation of the new MEPDG for future pavement design. (Abstract shortened by UMI.)

  9. Flexible cystoscopy.

    PubMed

    Kennedy, T J; Preminger, G M

    1988-08-01

    Flexible fiberoptic technology was first applied to cystoscopy in 1973, with greatly increased usage since 1982. Most procedures formerly performed with rigid cystoscopes can be done using flexible cystoscopes with minimal or no anesthesia. Patient positioning and precystocopy preparation and draping are simplified with the flexible fiberoptic instruments. Complete examination of the urethra and bladder can be performed with a single-lens system and with the patient in a variety of positions. Fiberoptic cystoscopy is limited in patients who are bleeding or have blood clots in their bladders. Withdrawal of irrigant or bladder drainage is cumbersome, and the fiberoptic image is currently not of the same caliber as that of the rigid-lens systems. Fiberoptic cystoscopy has become the procedure of choice for many urologists for ureteral stenting prior to extracorporeal shock-wave lithotripsy. With the advent of lithotripters that require no anesthesia, this application is likely to broaden. Future applications of flexible cystoscopy may include a flexible videocystoscope for use in diagnostic and therapeutic procedures. PMID:3407042

  10. Room temperature synthesis of cobalt-manganese-nickel oxalates micropolyhedrons for high-performance flexible electrochemical energy storage device.

    PubMed

    Zhang, Yi-Zhou; Zhao, Junhong; Xia, Jing; Wang, Lulu; Lai, Wen-Yong; Pang, Huan; Huang, Wei

    2015-01-01

    Cobalt-manganese-nickel oxalates micropolyhedrons were successfully fabricated by a room temperature chemical co-precipitation method. Interestingly, the Co0.5Mn0.4Ni0.1C2O4*nH2O micropolyhedrons and graphene nanosheets have been successfully applied as the positive and negative electrode materials (a battery type Faradaic electrode and a capacitive electrode, respectively) for flexible solid-state asymmetric supercapacitors. More importantly, the as-assembled device achieved a maximum energy density of 0.46 mWh·cm(-3), a decent result among devices with similar structures. The as-assembled device showed good flexibility, functioning well under both normal and bent conditions (0°-180°). The resulting device showed little performance decay even after 6000 cycles, which rendered the Co0.5Mn0.4Ni0.1C2O4*nH2O//Graphene device configuration a promising candidate for high-performance flexible solid-state asymmetric supercapacitors in the field of high-energy-density energy storage devices. PMID:25705048

  11. High-Performance Flexible All-Solid-State Supercapacitor from Large Free-Standing Graphene-PEDOT/PSS Films

    PubMed Central

    Liu, Yuqing; Weng, Bo; Razal, Joselito M.; Xu, Qun; Zhao, Chen; Hou, Yuyang; Seyedin, Shayan; Jalili, Rouhollah; Wallace, Gordon G.; Chen, Jun

    2015-01-01

    Although great attention has been paid to wearable electronic devices in recent years, flexible lightweight batteries or supercapacitors with high performance are still not readily available due to the limitations of the flexible electrode inventory. In this work, highly flexible, bendable and conductive rGO-PEDOT/PSS films were prepared using a simple bar-coating method. The assembled device using rGO-PEDOT/PSS electrode could be bent and rolled up without any decrease in electrochemical performance. A relatively high areal capacitance of 448 mF cm−2 was achieved at a scan rate of 10 mV s−1 using the composite electrode with a high mass loading (8.49 mg cm−2), indicating the potential to be used in practical applications. To demonstrate this applicability, a roll-up supercapacitor device was constructed, which illustrated the operation of a green LED light for 20 seconds when fully charged. PMID:26586106

  12. Directly-Grown Hierarchical Carbon Nanotube@Polypyrrole Core-Shell Hybrid for High-Performance Flexible Supercapacitors.

    PubMed

    Yesi, Yesi; Shown, Indrajit; Ganguly, Abhijit; Ngo, Trung Truc; Chen, Li-Chyong; Chen, Kuei-Hsien

    2016-02-01

    A hierarchical carbon nanotube-polypyrrole (CNT-PPy) core-shell composite was fabricated by growing CNTs directly on carbon cloth (CC) as a skeleton followed by electropolymerization of PPy with controlled polymerization time. Direct fabrication of electroactive (CNT-PPy) materials on the flexible CC electrode could reduce the interfacial resistance between the electrode and electrolyte and improve the ion diffusion. The supercapacitor electrode based on optimized PPy/CNT-CC exhibits excellent electrochemical performance, with the highest gravimetric capacitance being roughly 1038 F g(-1) per active mass of PPy and up to 486.1 F g(-1) per active mass of the PPy/CNT composite. Notably, excellent flexibility and cycle stability up to 10 000 cycles with only 18 % capacitance loss was achieved. At the same time, the fabricated asymmetric supercapacitor (PPy/CNT-CC∥CNT-CC) shows the maximum power density of 10 962 W kg(-1) at an energy density of 3.9 Wh kg(-1) under the operating potential of 1.4 V. The overall high cycle stability and high performance of the fabricated PPy/CNT-CC flexible electrode is due to the novel binder-free direct growth process. PMID:26791424

  13. Room temperature synthesis of cobalt-manganese-nickel oxalates micropolyhedrons for high-performance flexible electrochemical energy storage device

    PubMed Central

    Zhang, Yi-Zhou; Zhao, Junhong; Xia, Jing; Wang, Lulu; Lai, Wen-Yong; Pang, Huan; Huang, Wei

    2015-01-01

    Cobalt-manganese-nickel oxalates micropolyhedrons were successfully fabricated by a room temperature chemical co-precipitation method. Interestingly, the Co0.5Mn0.4Ni0.1C2O4*nH2O micropolyhedrons and graphene nanosheets have been successfully applied as the positive and negative electrode materials (a battery type Faradaic electrode and a capacitive electrode, respectively) for flexible solid-state asymmetric supercapacitors. More importantly, the as-assembled device achieved a maximum energy density of 0.46 mWh·cm−3, a decent result among devices with similar structures. The as-assembled device showed good flexibility, functioning well under both normal and bent conditions (0°–180°). The resulting device showed little performance decay even after 6000 cycles, which rendered the Co0.5Mn0.4Ni0.1C2O4*nH2O//Graphene device configuration a promising candidate for high-performance flexible solid-state asymmetric supercapacitors in the field of high-energy-density energy storage devices. PMID:25705048

  14. Room temperature synthesis of cobalt-manganese-nickel oxalates micropolyhedrons for high-performance flexible electrochemical energy storage device

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-Zhou; Zhao, Junhong; Xia, Jing; Wang, Lulu; Lai, Wen-Yong; Pang, Huan; Huang, Wei

    2015-02-01

    Cobalt-manganese-nickel oxalates micropolyhedrons were successfully fabricated by a room temperature chemical co-precipitation method. Interestingly, the Co0.5Mn0.4Ni0.1C2O4*nH2O micropolyhedrons and graphene nanosheets have been successfully applied as the positive and negative electrode materials (a battery type Faradaic electrode and a capacitive electrode, respectively) for flexible solid-state asymmetric supercapacitors. More importantly, the as-assembled device achieved a maximum energy density of 0.46 mWh.cm-3, a decent result among devices with similar structures. The as-assembled device showed good flexibility, functioning well under both normal and bent conditions (0°-180°). The resulting device showed little performance decay even after 6000 cycles, which rendered the Co0.5Mn0.4Ni0.1C2O4*nH2O//Graphene device configuration a promising candidate for high-performance flexible solid-state asymmetric supercapacitors in the field of high-energy-density energy storage devices.

  15. High-Performance Flexible All-Solid-State Supercapacitor from Large Free-Standing Graphene-PEDOT/PSS Films.

    PubMed

    Liu, Yuqing; Weng, Bo; Razal, Joselito M; Xu, Qun; Zhao, Chen; Hou, Yuyang; Seyedin, Shayan; Jalili, Rouhollah; Wallace, Gordon G; Chen, Jun

    2015-01-01

    Although great attention has been paid to wearable electronic devices in recent years, flexible lightweight batteries or supercapacitors with high performance are still not readily available due to the limitations of the flexible electrode inventory. In this work, highly flexible, bendable and conductive rGO-PEDOT/PSS films were prepared using a simple bar-coating method. The assembled device using rGO-PEDOT/PSS electrode could be bent and rolled up without any decrease in electrochemical performance. A relatively high areal capacitance of 448 mF cm(-2) was achieved at a scan rate of 10 mV s(-1) using the composite electrode with a high mass loading (8.49 mg cm(-2)), indicating the potential to be used in practical applications. To demonstrate this applicability, a roll-up supercapacitor device was constructed, which illustrated the operation of a green LED light for 20 seconds when fully charged. PMID:26586106

  16. Germanium nanoparticles encapsulated in flexible carbon nanofibers as self-supported electrodes for high performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Li, Weihan; Yang, Zhenzhong; Cheng, Jianxiu; Zhong, Xiongwu; Gu, Lin; Yu, Yan

    2014-04-01

    Germanium is a promising high-capacity anode material for lithium ion batteries, but still suffers from poor cyclability due to its huge volume variation during the Li-Ge alloy/dealloy process. Here we rationally designed a flexible and self-supported electrode consisting of Ge nanoparticles encapsulated in carbon nanofibers (Ge-CNFs) by using a facile electrospinning technique as potential anodes for Li-ion batteries. The Ge-CNFs exhibit excellent electrochemical performance with a reversible specific capacity of ~1420 mA h g-1 after 100 cycles at 0.15 C with only 0.1% decay per cycle (the theoretical specific capacity of Ge is 1624 mA h g-1). When cycled at a high current of 1 C, they still deliver a reversible specific capacity of 829 mA h g-1 after 250 cycles. The strategy and design are simple, effective, and versatile. This type of flexible electrodes is a promising solution for the development of flexible lithium-ion batteries with high power and energy densities.Germanium is a promising high-capacity anode material for lithium ion batteries, but still suffers from poor cyclability due to its huge volume variation during the Li-Ge alloy/dealloy process. Here we rationally designed a flexible and self-supported electrode consisting of Ge nanoparticles encapsulated in carbon nanofibers (Ge-CNFs) by using a facile electrospinning technique as potential anodes for Li-ion batteries. The Ge-CNFs exhibit excellent electrochemical performance with a reversible specific capacity of ~1420 mA h g-1 after 100 cycles at 0.15 C with only 0.1% decay per cycle (the theoretical specific capacity of Ge is 1624 mA h g-1). When cycled at a high current of 1 C, they still deliver a reversible specific capacity of 829 mA h g-1 after 250 cycles. The strategy and design are simple, effective, and versatile. This type of flexible electrodes is a promising solution for the development of flexible lithium-ion batteries with high power and energy densities. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00140k

  17. Pattern recognition algorithms for density estimation of asphalt pavement during compaction: a simulation study

    NASA Astrophysics Data System (ADS)

    Shangguan, Pengcheng; Al-Qadi, Imad L.; Lahouar, Samer

    2014-08-01

    This paper presents the application of artificial neural network (ANN) based pattern recognition to extract the density information of asphalt pavement from simulated ground penetrating radar (GPR) signals. This study is part of research efforts into the application of GPR to monitor asphalt pavement density during compaction. The main challenge is to eliminate the effect of roller-sprayed water on GPR signals during compaction and to extract density information accurately. A calibration of the excitation function was conducted to provide an accurate match between the simulated signal and the real signal. A modified electromagnetic mixing model was then used to calculate the dielectric constant of asphalt mixture with water. A large database of GPR responses was generated from pavement models having different air void contents and various surface moisture contents using finite-difference time-domain simulation. Feature extraction was performed to extract density-related features from the simulated GPR responses. Air void contents were divided into five classes representing different compaction statuses. An ANN-based pattern recognition system was trained using the extracted features as inputs and air void content classes as target outputs. Accuracy of the system was tested using test data set. Classification of air void contents using the developed algorithm is found to be highly accurate, which indicates effectiveness of this method to predict asphalt concrete density.

  18. Laser scanning on road pavements: a new approach for characterizing surface texture.

    PubMed

    Bitelli, Gabriele; Simone, Andrea; Girardi, Fabrizio; Lantieri, Claudio

    2012-01-01

    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. PMID:23012535

  19. Ground rubber use in asphalt paving mixtures: A design and performance evaluation. Executive summary. Final report, 1 July 1991-30 June 1994

    SciTech Connect

    Khosla, N.P.; Malpass, G.A.

    1994-10-01

    The main objectives of the study were: (1) To determine if existing pavement mixture design procedures could be used in the design of rubberized pavements; (2) To determine the performance characteristics of rubberized mixtures in terms of crackng and rutting potential; (3) To compare the performance of rubberized and conventional pavement systems using a computer based performance prediction model; (4) To compare the life cycle costs of rubberized and conventional pavement systems.

  20. Novel prescribed performance neural control of a flexible air-breathing hypersonic vehicle with unknown initial errors.

    PubMed

    Bu, Xiangwei; Wu, Xiaoyan; Zhu, Fujing; Huang, Jiaqi; Ma, Zhen; Zhang, Rui

    2015-11-01

    A novel prescribed performance neural controller with unknown initial errors is addressed for the longitudinal dynamic model of a flexible air-breathing hypersonic vehicle (FAHV) subject to parametric uncertainties. Different from traditional prescribed performance control (PPC) requiring that the initial errors have to be known accurately, this paper investigates the tracking control without accurate initial errors via exploiting a new performance function. A combined neural back-stepping and minimal learning parameter (MLP) technology is employed for exploring a prescribed performance controller that provides robust tracking of velocity and altitude reference trajectories. The highlight is that the transient performance of velocity and altitude tracking errors is satisfactory and the computational load of neural approximation is low. Finally, numerical simulation results from a nonlinear FAHV model demonstrate the efficacy of the proposed strategy. PMID:26456727

  1. Recycled materials in asphalt pavements. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning the recycling of asphalt pavement materials, and the use of other recycled materials to manufacture asphalt pavement. Articles discuss methods used for recycling bituminous pavement including hot-mix and cold-mix. Materials used to improve recycled pavement, and recycled materials used in asphalt pavement include latexes, rubber scrap such as tires, glass shards, concretes, dusts, waste oils, roofing wastes, sulfur, and metal refining sludges. Testing and evaluation of recycled pavements both in laboratories and in test cases are considered. (Contains a minimum of 160 citations and includes a subject term index and title list.)

  2. High performance photoswitches based on flexible and amorphous D-A polymer nanowires.

    PubMed

    Liu, Yao; Wang, Haifeng; Dong, Huanli; Jiang, Lang; Hu, Wenping; Zhan, Xiaowei

    2013-01-28

    A fluorene-based donor-acceptor conjugated polymer is synthesized and the polymer nanowires are successfully prepared with high quality and large scale using a simple and practical template dipping method. These amorphous polymer nanowires are flexible and show excellent photoconductive properties with reliable reproducibility. The individual nanowire photoswitches exhibit a responsivity as high as 1700 mA W(-1) and an on/off ratio as high as 2000 under a light intensity of 5.76 mW cm(-2) and a driving voltage of 40 V. PMID:22987536

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

    NASA Astrophysics Data System (ADS)

    Georgiou, Panos; Loizos, Fokion

    2015-04-01

    Field compaction of asphalt pavements is ultimately conducted to achieve layer(s) with suitable mechanical stability. However, the achieved degree of compaction has a significant influence on the performance of asphalt pavements. Providing all desirable mixture design characteristics without adequate compaction could lead to premature permanent deformation, excessive aging, and moisture damage; these distresses reduce the useful life of asphalt pavements. Hence, proper construction of an asphalt pavement is necessary to develop a long lasting roadway that will help minimize future maintenance. This goal is achieved by verifying and confirming that design specifications, in this case density specifications are met through the use of Quality Assurance (QA) practices. With respect to in-situ compaction degree of hot mix asphalt (HMA) pavement surface layers, nearly all agencies specify either cored samples or nuclear/ non nuclear density gauges to provide density measurement of the constructed pavement. Typically, a small number of spot tests (with either cores or nuclear gauges) are run and a judgment about the density level of the entire roadway is made based on the results of this spot testing. Unfortunately, density measurement from a small number of spots may not be representative of the density of the pavement mat. Hence, full coverage evaluation of compaction quality of the pavement mat is needed. The Ground Penetrating Radar (GPR), as a Non Destructive Testing (NDT) technique, is an example of a non-intrusive technique that favors over the methods mentioned above for assessing compaction quality of asphalt pavements, since it allows measurement of all mat areas. Further, research studies in recent years have shown promising results with respect to its capability, coupled with the use of novel algorithms based on the dielectric properties of HMA, to predict the in-situ field density. In view of the above, field experimental surveys were conducted to assess the effectiveness of GPR methodology to estimate the in-situ compaction degree of several test sections. Moreover, considering also the field density results as obtained with traditional methods, comparative evaluation was conducted to assess the potential of using the GPR technique as a surrogate tool for pavement compaction quality purposes. Acknowledgements: This work has been inspired from publications of the COST action TU-1208 funded from EU.

  4. Post-Glacial Ant Generated Desert Pavements in Southeastern Oregon

    NASA Astrophysics Data System (ADS)

    Leonard, K. C.

    2001-12-01

    Desert pavements typically require thousands to tens of thousands of years to reach a high level of development. In a pluvial lake valley in Southeastern Oregon I have observed harvester ants creating desert pavement-like features in less than two months. The summer lake basin is a fairly simple sedimentary system. In the eastern half of the basin, the basaltic bedrock is buried under tens of meters of alluvial deposits which lie beneath an approximately ten meter thick dune sheet. The dune sands are noticably different in grainsize and chemistry than the fine component of the alluvial deposits. The dunes began to form at the end of the last pluvial interval (Allison 1980) and continue to be active today. Roughly one fourth of the total area of the dune sheet is mantled with desert pavement, consisting of very coarse sand and fine pebbles (1-8 mm diameter). The dune sand is very fine grained with a considerable amount of silt and minimal clay. It forms thin (2-20 cm thick) well developed Av horizons beneath the desert pavement. Owyhee harvester ants (Pogonomyrmex owyheei) in the area use pebbles of the same size and petrology as the desert pavements to construct their hills. For the ants the closest source of these pebbles is often the alluvium, ten meters below the anthill, rather than in a desert pavement deposit at some distance away overland. An experiment conducted between June and August 1999 demonstrated that the ants rebuild their hills with newly excavated pebbles. When the colonies die off after 5-25 years, the pebbles are stranded at the surface. Processes such as those described by Haff and Werner (1996), where jackrabbits and birds were observed kicking desert pavement clasts aross the ground serve to redistribute the pebbles across the surface of the sand dunes. The sand dunes have been forming over an 8000 year period. Based on anthill-regrowth measurements, the lifespan of an individual colony of harvester ants leads to the excavation of only enough pebbles to cover a two meter square area with desert pavement. This study has determined the quantity of desert pavement currently present at the surface of the sand dunes, and the timescale over which ants can excavate pebbles from the alluvium. The episodic nature of ant colony activity remains to be fully incorporated into the study of desert pavement, usually thought of as a static landform.

  5. High-performance NiO/Ag/NiO transparent electrodes for flexible organic photovoltaic cells.

    PubMed

    Xue, Zhichao; Liu, Xingyuan; Zhang, Nan; Chen, Hong; Zheng, Xuanming; Wang, Haiyu; Guo, Xiaoyang

    2014-09-24

    Transparent electrodes with a dielectric-metal-dielectric (DMD) structure can be implemented in a simple manufacturing process and have good optical and electrical properties. In this study, nickel oxide (NiO) is introduced into the DMD structure as a more appropriate dielectric material that has a high conduction band for electron blocking and a low valence band for efficient hole transport. The indium-free NiO/Ag/NiO (NAN) transparent electrode exhibits an adjustable high transmittance of ∼82% combined with a low sheet resistance of ∼7.6 Ω·s·q(-1) and a work function of 5.3 eV after UVO treatment. The NAN electrode shows excellent surface morphology and good thermal, humidity, and environmental stabilities. Only a small change in sheet resistance can be found after NAN electrode is preserved in air for 1 year. The power conversion efficiencies of organic photovoltaic cells with NAN electrodes deposited on glass and polyethylene terephthalate (PET) substrates are 6.07 and 5.55%, respectively, which are competitive with those of indium tin oxide (ITO)-based devices. Good photoelectric properties, the low-cost material, and the room-temperature deposition process imply that NAN electrode is a striking candidate for low-cost and flexible transparent electrode for efficient flexible optoelectronic devices. PMID:25148532

  6. Ultrahigh Performance C60 Nanorod Large Area Flexible Photoconductor Devices via Ultralow Organic and Inorganic Photodoping

    PubMed Central

    Saran, Rinku; Stolojan, Vlad; Curry, Richard J.

    2014-01-01

    One dimensional single-crystal nanorods of C60 possess unique optoelectronic properties including high electron mobility, high photosensitivity and an excellent electron accepting nature. In addition, their rapid large scale synthesis at room temperature makes these organic semiconducting nanorods highly attractive for advanced optoelectronic device applications. Here, we report low-cost large-area flexible photoconductor devices fabricated using C60 nanorods. We demonstrate that the photosensitivity of the C60 nanorods can be enhanced ~400-fold via an ultralow photodoping mechanism. The photodoped devices offer broadband UV-vis-NIR spectral tuneability, exhibit a detectivitiy >109 Jones, an external quantum efficiency of ~100%, a linear dynamic range of 80 dB, a rise time 60 µs and the ability to measure ac signals up to ~250 kHz. These figures of merit combined are among the highest reported for one dimensional organic and inorganic large-area planar photoconductors and are competitive with commercially available inorganic photoconductors and photoconductive cells. With the additional processing benefits providing compatibility with large-area flexible platforms, these devices represent significant advances and make C60 nanorods a promising candidate for advanced photodetector technologies. PMID:24853479

  7. High-performance flexible energy storage and harvesting system for wearable electronics.

    PubMed

    Ostfeld, Aminy E; Gaikwad, Abhinav M; Khan, Yasser; Arias, Ana C

    2016-01-01

    This paper reports on the design and operation of a flexible power source integrating a lithium ion battery and amorphous silicon solar module, optimized to supply power to a wearable health monitoring device. The battery consists of printed anode and cathode layers based on graphite and lithium cobalt oxide, respectively, on thin flexible current collectors. It displays energy density of 6.98 mWh/cm(2) and demonstrates capacity retention of 90% at 3C discharge rate and ~99% under 100 charge/discharge cycles and 600 cycles of mechanical flexing. A solar module with appropriate voltage and dimensions is used to charge the battery under both full sun and indoor illumination conditions, and the addition of the solar module is shown to extend the battery lifetime between charging cycles while powering a load. Furthermore, we show that by selecting the appropriate load duty cycle, the average load current can be matched to the solar module current and the battery can be maintained at a constant state of charge. Finally, the battery is used to power a pulse oximeter, demonstrating its effectiveness as a power source for wearable medical devices. PMID:27184194

  8. Carbon nanotube network film directly grown on carbon cloth for high-performance solid-state flexible supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhou, Cheng; Liu, Jinping

    2014-01-01

    Carbon nanotubes (CNTs) have received increasing attention as electrode materials for high-performance supercapacitors. We herein present a straightforward method to synthesize CNT films directly on carbon cloths as electrodes for all-solid-state flexible supercapacitors (AFSCs). The as-made highly conductive electrodes possess a three-dimensional (3D) network architecture for fast ion diffusion and good flexibility, leading to an AFSC with a specific capacitance of 106.1 F g-1, an areal capacitance of 38.75 mF cm-2, an ultralong cycle life of 100 000 times (capacitance retention: 99%), a good rate capability (can scan at 1000 mV s-1, at which the capacitance is still ˜37.8% of that at 5 mV s-1), a high energy density (2.4 μW h cm-2) and a high power density (19 mW cm-2). Moreover, our AFSC maintains excellent electrochemical attributes even with serious shape deformation (bending, folding, etc), high mechanical pressure (63 kPa) and a wide temperature window (up to 100 ° C). After charging for only 5 s, three such AFSC devices connected in series can efficiently power a red round LED for 60 s. Our work could pave the way for the design of practical AFSCs, which are expected to be used for various flexible portable/wearable electronic devices in the future.

  9. High-performance bilayer flexible resistive random access memory based on low-temperature thermal atomic layer deposition

    PubMed Central

    2013-01-01

    We demonstrated a flexible resistive random access memory device through a low-temperature atomic layer deposition process. The device is composed of an HfO2/Al2O3-based functional stack on an indium tin oxide-coated polyethylene terephthalate substrate. After the initial reset operation, the device exhibits a typical bipolar, reliable, and reproducible resistive switching behavior. After a 104-s retention time, the memory window of the device is still in accordance with excellent thermal stability, and a 10-year usage is still possible with the resistance ratio larger than 10 at room temperature and at 85°C. In addition, the operation speed of the device was estimated to be 500 ns for the reset operation and 800 ns for the set operation, which is fast enough for the usage of the memories in flexible circuits. Considering the excellent performance of the device fabricated by low-temperature atomic layer deposition, the process may promote the potential applications of oxide-based resistive random access memory in flexible integrated circuits. PMID:23421424

  10. Flexible Hybrid Membranes with Ni(OH)2 Nanoplatelets Vertically Grown on Electrospun Carbon Nanofibers for High-Performance Supercapacitors.

    PubMed

    Zhang, Longsheng; Ding, Qianwei; Huang, Yunpeng; Gu, Huahao; Miao, Yue-E; Liu, Tianxi

    2015-10-14

    The practical applications of transition metal oxides and hydroxides for supercapacitors are restricted by their intrinsic poor conductivity, large volumetric expansion, and rapid capacitance fading upon cycling, which can be solved by optimizing these materials to nanostructures and confining them within conductive carbonaceous frameworks. In this work, flexible hybrid membranes with ultrathin Ni(OH)2 nanoplatelets vertically and uniformly anchored on the electrospun carbon nanofibers (CNF) have been facilely prepared as electrode materials for supercapacitors. The Ni(OH)2/CNF hybrid membranes with three-dimensional macroporous architectures as well as hierarchical nanostructures can provide open and continuous channels for rapid diffusion of electrolyte to access the electrochemically active Ni(OH)2 nanoplatelets. Moreover, the carbon nanofiber can act both as a conductive core to provide efficient transport of electrons for fast Faradaic redox reactions of the Ni(OH)2 sheath, and as a buffering matrix to mitigate the local volumetric expansion/contraction upon long-term cycling. As a consequence, the optimized Ni(OH)2/CNF hybrid membrane exhibits a high specific capacitance of 2523 F g(-1) (based on the mass of Ni(OH)2, that is 701 F g(-1) based on the total mass) at a scan rate of 5 mV s(-1). The Ni(OH)2/CNF hybrid membranes with high mechanical flexibility, superior electrical conductivity, and remarkably improved electrochemical capacitance are condsidered as promising flexible electrode materials for high-performance supercapacitors. PMID:26390298

  11. Carbon nanotube network film directly grown on carbon cloth for high-performance solid-state flexible supercapacitors.

    PubMed

    Zhou, Cheng; Liu, Jinping

    2014-01-24

    Carbon nanotubes (CNTs) have received increasing attention as electrode materials for high-performance supercapacitors. We herein present a straightforward method to synthesize CNT films directly on carbon cloths as electrodes for all-solid-state flexible supercapacitors (AFSCs). The as-made highly conductive electrodes possess a three-dimensional (3D) network architecture for fast ion diffusion and good flexibility, leading to an AFSC with a specific capacitance of 106.1 F g−1, an areal capacitance of 38.75 mF cm−2, an ultralong cycle life of 100,000 times (capacitance retention: 99%), a good rate capability (can scan at 1000 mV s−1, at which the capacitance is still ~37.8% of that at 5 mV s−1), a high energy density (2.4 μW h cm−2) and a high power density (19 mW cm−2). Moreover, our AFSC maintains excellent electrochemical attributes even with serious shape deformation (bending, folding, etc), high mechanical pressure (63 kPa) and a wide temperature window (up to 100° C). After charging for only 5 s, three such AFSC devices connected in series can efficiently power a red round LED for 60 s. Our work could pave the way for the design of practical AFSCs, which are expected to be used for various flexible portable/wearable electronic devices in the future. PMID:24356470

  12. 3D Graphene-Infused Polyimide with Enhanced Electrothermal Performance for Long-Term Flexible Space Applications.

    PubMed

    Loeblein, Manuela; Bolker, Asaf; Tsang, Siu Hon; Atar, Nurit; Uzan-Saguy, Cecile; Verker, Ronen; Gouzman, Irina; Grossman, Eitan; Teo, Edwin Hang Tong

    2015-12-22

    Polyimides (PIs) have been praised for their high thermal stability, high modulus of elasticity and tensile strength, ease of fabrication, and moldability. They are currently the standard choice for both substrates for flexible electronics and space shielding, as they render high temperature and UV stability and toughness. However, their poor thermal conductivity and completely electrically insulating characteristics have caused other limitations, such as thermal management challenges for flexible high-power electronics and spacecraft electrostatic charging. In order to target these issues, a hybrid of PI with 3D-graphene (3D-C), 3D-C/PI, is developed here. This composite renders extraordinary enhancements of thermal conductivity (one order of magnitude) and electrical conductivity (10 orders of magnitude). It withstands and keeps a stable performance throughout various bending and thermal cycles, as well as the oxidative and aggressive environment of ground-based, simulated space environments. This makes this new hybrid film a suitable material for flexible space applications. PMID:26479496

  13. Intra-Seasonal Flexibility in Avian Metabolic Performance Highlights the Uncoupling of Basal Metabolic Rate and Thermogenic Capacity

    PubMed Central

    Petit, Magali; Lewden, Agnès; Vézina, François

    2013-01-01

    Stochastic winter weather events are predicted to increase in occurrence and amplitude at northern latitudes and organisms are expected to cope through phenotypic flexibility. Small avian species wintering in these environments show acclimatization where basal metabolic rate (BMR) and maximal thermogenic capacity (MSUM) are typically elevated. However, little is known on intra-seasonal variation in metabolic performance and on how population trends truly reflect individual flexibility. Here we report intra-seasonal variation in metabolic parameters measured at the population and individual levels in black-capped chickadees (Poecileatricapillus). Results confirmed that population patterns indeed reflect flexibility at the individual level. They showed the expected increase in BMR (6%) and MSUM (34%) in winter relative to summer but also, and most importantly, that these parameters changed differently through time. BMR began its seasonal increase in November, while MSUM had already achieved more than 20% of its inter-seasonal increase by October, and declined to its starting level by March, while MSUM remained high. Although both parameters co-vary on a yearly scale, this mismatch in the timing of variation in winter BMR and MSUM likely reflects different constraints acting on different physiological components and therefore suggests a lack of functional link between these parameters. PMID:23840843

  14. 3D GPR investigation of pavement using 1 GHz and 2 GHz horn type antenna - comparison of the results

    NASA Astrophysics Data System (ADS)

    Grinč, Michal

    2015-03-01

    Today, non-invasive, simple, safe, time efficient and traffic flow non-disturbing methods of the pavement diagnostics are requested. From this point of view a very convenient method seems to be the GPR investigation. The trial GPR survey of the Žilina airport was carried out in order to investigate the pavement of the runway. A testing field is placed where the geological drill hole has been drilled out. The GPR survey was performed in 3D geometry, hence in x and y directions. Two horn type antennas with central frequencies of 1 GHz and 2 GHz were used on the test field in order to verify thicknesses of pavement construction layers Here, the results of both 3D measurements are compared to each other However the investigation confirms two subhorizontal construction layers of the runway pavement, the results obtained in y-direction slightly differ at some areas. These errors are situated mainly in the areas where the linear cracks are found. On the other hand, results in x-directions are within standard error.

  15. Recycling of plastic and rubber tire waste in asphalt pavements

    SciTech Connect

    Morrison, G.R.; Lee, N.K.; Hesp, S.A.M.

    1994-12-31

    This paper discusses some important issues related to the use of recycled thermoplastics and rubber tire waste in asphalt binders for hot-mix pavements. Both high temperature rheological and low temperature fracture studies are presented on recycled polyethylene, devulcanized and crumb rubber-modified asphalt binders. The results are compared to unmodified and commercially available modified binders. This research is especially timely in light of the US Intermodal Surface Transportation Efficiency Act of 1991, Section 1038 which, starting in 1995, will force state and local governments to use significant amounts of recycled rubber tire or plastic waste in federally funded highway projects. High temperature rheological measurements of the loss modulus, loss tangent and complex modulus show a significant improvement when only small quantities of crumb rubber, devulcanized crumb rubber or waste polyethylene are added to the asphalt binders. The low temperature fracture performance of the modified asphalts is greatly influenced by the interfacial strength between the dispersed and continuous phase. The fracture toughness increases dramatically, only when low molecular weight polymers are grafted in-situ onto the rubber and polymer dispersed phases in order to strength the interface. This points to a crack-pinning mechanism as being responsible for the dramatic increase in fracture toughness that is observed in this work. Single phase, devulcanized crumb rubber-asphalt systems perform quite poorly at low temperatures.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  17. Analytic Transfer Functions for the Dynamics & Control of Flexible Rotating Spacecraft Performing Large Angle Maneuvers

    NASA Astrophysics Data System (ADS)

    Elgohary, Tarek A.; Turner, James D.; Junkins, John L.

    2015-07-01

    A symmetric flexible rotating spacecraft can be modeled as a distributed parameter system of a rigid hub attached to two flexible appendages with tip masses. First, Hamilton's extended principle is utilized to establish a general treatment for deriving the dynamics of multi-body dynamical systems to establish a hybrid system of integro-partial differential equations that model the evolution of the system in space and time. A Generalized State Space (GSS) system of equations is constructed in the frequency domain to obtain analytic transfer functions for the rotating spacecraft. This model does not include spatial discretization. The frequency response of the generally modeled spacecraft and a special case with no tip masses are presented. Numerical results for the system frequency response obtained from the analytic transfer functions are presented and compared against the classical assumed modes numerical method with two choices of admissible functions. The truncation-error-free analytic results are used to validate the numerical approximations and to agree well with the classical widely used finite dimensional numerical solutions. Fundamentally, we show that the rigorous transfer function, without introduction of spatial discretization, can be directly used in control law design with a guarantee of Lyapunov stable closed loop dynamics. The frequency response of the system is used in a classical control problem where the Lyapunov stable controller is derived and tested for gain selection. The correlation between the controller design in the frequency domain utilizing the analytic transfer functions and the system response is analyzed and verified. The derived analytic transfer functions provide a powerful tool to test various control schemes in the frequency domain and a validation platform for existing numerical methods for distributed parameters models. The same platform has been used to obtain the frequency response of more complex beam models following Timoshenko beam theory and the control problem for such models can be pursued in future works.

  18. Analytic Transfer Functions for the Dynamics & Control of Flexible Rotating Spacecraft Performing Large Angle Maneuvers

    NASA Astrophysics Data System (ADS)

    Elgohary, Tarek A.; Turner, James D.; Junkins, John L.

    2015-06-01

    A symmetric flexible rotating spacecraft can be modeled as a distributed parameter system of a rigid hub attached to two flexible appendages with tip masses. First, Hamilton's extended principle is utilized to establish a general treatment for deriving the dynamics of multi-body dynamical systems to establish a hybrid system of integro-partial differential equations that model the evolution of the system in space and time. A Generalized State Space (GSS) system of equations is constructed in the frequency domain to obtain analytic transfer functions for the rotating spacecraft. This model does not include spatial discretization. The frequency response of the generally modeled spacecraft and a special case with no tip masses are presented. Numerical results for the system frequency response obtained from the analytic transfer functions are presented and compared against the classical assumed modes numerical method with two choices of admissible functions. The truncation-error-free analytic results are used to validate the numerical approximations and to agree well with the classical widely used finite dimensional numerical solutions. Fundamentally, we show that the rigorous transfer function, without introduction of spatial discretization, can be directly used in control law design with a guarantee of Lyapunov stable closed loop dynamics. The frequency response of the system is used in a classical control problem where the Lyapunov stable controller is derived and tested for gain selection. The correlation between the controller design in the frequency domain utilizing the analytic transfer functions and the system response is analyzed and verified. The derived analytic transfer functions provide a powerful tool to test various control schemes in the frequency domain and a validation platform for existing numerical methods for distributed parameters models. The same platform has been used to obtain the frequency response of more complex beam models following Timoshenko beam theory and the control problem for such models can be pursued in future works.

  19. Pulsed laser annealing for advanced performance of mechanically flexible and optically transparent multilayer MoS2 transistors (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Kwon, Hyuk-Jun; Choi, Woong; Oh, Min Suk; Kim, Sunkook; Grigoropoulos, Costas P.

    2015-09-01

    Laser enables the achievement of superb interfacial characteristics between electrode and semiconducting material contact surface and is also useful for a reduction in contact resistance. The irradiation of a pulsed laser with high energy density and short wavelength onto the electrodes leads to thermal annealing at the locally confined small area that needs high temperature without inflicting thermal damage. This contrasts conventional thermal annealing that affects the entire panel, including unwanted areas in which the annealing process should be excluded. We demonstrate that mechanically flexible and optically transparent (more than 81% transmittance in visible wavelength) multilayered molybdenum disulfide (MoS2) thin-film transistors (TFTs) in which the source/drain electrodes are selectively annealed using picosecond laser achieve the enhancement of device performance without plastic deformation, such as higher mobility, increased output resistance, and decreased subthreshold swing. Numerical thermal simulation for the temperature distribution, transmission electron microscopy (TEM) analysis, current-voltage measurements, and contact-free mobility extracted from the Y-function method (YFM) enable understanding of the compatibility and the effects of pulsed laser annealing process; the enhanced performance originated not only from a decrease in the Schottky barrier effect at the contact, but also an improvement of the channel interface. Furthermore, these results show that the laser annealing can be a promising technology to build up a high performance transparent and flexible electronics.

  20. Membranes of MnO Beading in Carbon Nanofibers as Flexible Anodes for High-Performance Lithium-Ion Batteries

    PubMed Central

    Zhao, Xin; Du, Yuxuan; Jin, Lei; Yang, Yang; Wu, Shuilin; Li, Weihan; Yu, Yan; Zhu, Yanwu; Zhang, Qinghua

    2015-01-01

    Freestanding yet flexible membranes of MnO/carbon nanofibers are successfully fabricated through incorporating MnO2 nanowires into polymer solution by a facile electrospinning technique. During the stabilization and carbonization processes of the as-spun membranes, MnO2 nanowires are transformed to MnO nanoparticles coincided with a conversion of the polymer from an amorphous state to a graphitic structure of carbon nanofibers. The hybrids consist of isolated MnO nanoparticles beading in the porous carbon and demonstrate superior performance when being used as a binder-free anode for lithium-ion batteries. With an optimized amount of MnO (34.6 wt%), the anode exhibits a reversible capacity of as high as 987.3 mAh g−1 after 150 discharge/charge cycles at 0.1 A g−1, a good rate capability (406.1 mAh g−1 at 3  A g−1) and an excellent cycling performance (655 mAh g−1 over 280 cycles at 0.5 A g−1). Furthermore, the hybrid anode maintains a good electrochemical performance at bending state as a flexible electrode. PMID:26374601

  1. The influence of low-order chord-wise flexibility on the performance of a flapping wing

    NASA Astrophysics Data System (ADS)

    Toomey, Jonathan; Eldredge, Jeff D.

    2008-11-01

    The aerodynamic role of flexible fight structures in airborne creatures is still poorly understood. The objective of this study is to distill the basic phenomena of flapping with deformable wings for their use in the efficient design of bio-inspired flight vehicles. The target of the study is a two-dimensional wing with rigid components connected by damped torsion springs. This simplified structure reduces the complexity of the problem, while retaining the leading-order influence of wing flexion. The motion of the leading portion of the wing is prescribed with hovering-type kinematics, while the trailing portions respond passively. Numerical simulations are performed with a viscous vortex particle method with strongly-coupled structural dynamics. The investigation focuses on the influences of several key parameters: spring stiffness (from rigid to very flexible), the location of axis of rotation, and the timing between the rotational and translational components of the kinematics. The effects are quantified via several performance measures, including production of mean and rms lift, the mean consumption of power, and the lift per unit power. Some important correlations are identified between the input parameters and the performance metrics, the passive wing deflection and the wake structure. It is shown that variation in the rotation phase lead are accompanied by topological changes in the wake vortex dynamics.

  2. Membranes of MnO Beading in Carbon Nanofibers as Flexible Anodes for High-Performance Lithium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Du, Yuxuan; Jin, Lei; Yang, Yang; Wu, Shuilin; Li, Weihan; Yu, Yan; Zhu, Yanwu; Zhang, Qinghua

    2015-09-01

    Freestanding yet flexible membranes of MnO/carbon nanofibers are successfully fabricated through incorporating MnO2 nanowires into polymer solution by a facile electrospinning technique. During the stabilization and carbonization processes of the as-spun membranes, MnO2 nanowires are transformed to MnO nanoparticles coincided with a conversion of the polymer from an amorphous state to a graphitic structure of carbon nanofibers. The hybrids consist of isolated MnO nanoparticles beading in the porous carbon and demonstrate superior performance when being used as a binder-free anode for lithium-ion batteries. With an optimized amount of MnO (34.6 wt%), the anode exhibits a reversible capacity of as high as 987.3 mAh g-1 after 150 discharge/charge cycles at 0.1 A g-1, a good rate capability (406.1 mAh g-1 at 3  A g-1) and an excellent cycling performance (655 mAh g-1 over 280 cycles at 0.5 A g-1). Furthermore, the hybrid anode maintains a good electrochemical performance at bending state as a flexible electrode.

  3. POROUS PAVEMENT PHASE I DESIGN AND OPERATIONAL CRITERIA (EPA/600/2-80/135)

    EPA Science Inventory

    Design and operational criteria, utilization concepts, benefits and disadvantages, as well as other characteristics of porous pavements are presented in this report. Particular emphasis is placed on porous asphalt pavements, but the criteria and design approach are applicable to ...

  4. Evaluation of Three Porous Pavement Systems in a Newly Constructed Parking Lot

    EPA Science Inventory

    This project examines porous pavement systems in a newly constructed parking lot next to Building 205 at the Edison Environmental Center. Porous pavement systems are one means of promoting environmental sustainability through stormwater runoff reduction. This project examines t...

  5. Aerodynamic performance of two-dimensional, chordwise flexible flapping wings at fruit fly scale in hover flight.

    PubMed

    Sridhar, Madhu; Kang, Chang-kwon

    2015-06-01

    Fruit flies have flexible wings that deform during flight. To explore the fluid-structure interaction of flexible flapping wings at fruit fly scale, we use a well-validated Navier-Stokes equation solver, fully-coupled with a structural dynamics solver. Effects of chordwise flexibility on a two dimensional hovering wing is studied. Resulting wing rotation is purely passive, due to the dynamic balance between aerodynamic loading, elastic restoring force, and inertial force of the wing. Hover flight is considered at a Reynolds number of Re = 100, equivalent to that of fruit flies. The thickness and density of the wing also corresponds to a fruit fly wing. The wing stiffness and motion amplitude are varied to assess their influences on the resulting aerodynamic performance and structural response. Highest lift coefficient of 3.3 was obtained at the lowest-amplitude, highest-frequency motion (reduced frequency of 3.0) at the lowest stiffness (frequency ratio of 0.7) wing within the range of the current study, although the corresponding power required was also the highest. Optimal efficiency was achieved for a lower reduced frequency of 0.3 and frequency ratio 0.35. Compared to the water tunnel scale with water as the surrounding fluid instead of air, the resulting vortex dynamics and aerodynamic performance remained similar for the optimal efficiency motion, while the structural response varied significantly. Despite these differences, the time-averaged lift scaled with the dimensionless shape deformation parameter γ. Moreover, the wing kinematics that resulted in the optimal efficiency motion was closely aligned to the fruit fly measurements, suggesting that fruit fly flight aims to conserve energy, rather than to generate large forces. PMID:25946079

  6. Nondestructive pavement evaluation technique using falling weight deflectometer

    SciTech Connect

    Al-Nageim, H.; Al-Hakim, B.; Lesley, L.

    1996-11-01

    An analytical method to predict the mechanical properties of a multi-layer pavement structure is presented. The development of the model is based on a modified back calculation model, using a finite circular plate resting on an elastic layered system. The deflection of the pavement under the dynamic action of the falling weight deflectometer (FWD) is taken as a function of the load action and the characteristic strength of the layers comprising the system including the friction between the individual layers. The responses of the pavement during the impact loading of the falling weight are measured and analyzed to predict the stress, strain and coefficient of friction between the layers making the system. The results revealed that the model which incorporates the interface of friction coefficient in the back-analysis technique allows for a more accurate calculation of the mechanical properties of the pavements and thus can be used as a quality control to assess the state of adhesion between the pavement layer system.

  7. Urban evaporation rates for water-permeable pavements.

    PubMed

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

    2010-01-01

    In urban areas the natural water balance is disturbed. Infiltration and evaporation are reduced, resulting in a high surface runoff and a typical city climate, which can lead to floods and damages. Water-permeable pavements have a high infiltration rate that reduces surface runoff by increasing the groundwater recharge. The high water retention capacity of the street body of up to 51 l/m(2) and its connection via pores to the surface lead to higher evaporation rates than impermeable surfaces. A comparison of these two kinds of pavements shows a 16% increase in evaporation levels of water-permeable pavements. Furthermore, the evaporation from impermeable pavements is linked directly to rain events due to fast-drying surfaces. Water-permeable pavements show a more evenly distributed evaporation after a rain event. Cooling effects by evaporative heat loss can improve the city climate even several days after rain events. On a large scale use, uncomfortable weather like sultriness or dry heat can be prevented and the urban water balance can be attenuated towards the natural. PMID:20818060

  8. Use of stabilized bottom ash for bound layers of road pavements.

    PubMed

    Toraldo, Emanuele; Saponaro, Sabrina; Careghini, Alessandro; Mariani, Edoardo

    2013-05-30

    This paper reports about the lab scale results obtained by using stabilized bottom ash (SBA) from an Italian municipal solid waste incinerator as aggregates in cement-bound mixes and asphalt concretes for road pavements. The investigation focused on SBA content. From the road construction point of view, performance related to compaction, volumetric and mechanical properties were assessed. The environmental aspects were investigated performing leaching tests. The results suggested that SBA satisfied the environmental Italian law for reuse of non-hazardous waste but affected significantly the stress-strain behavior of the final products. Therefore a maximum percentage of 10% was suggested. PMID:23535513

  9. Self-Assembled N/S Codoped Flexible Graphene Paper for High Performance Energy Storage and Oxygen Reduction Reaction.

    PubMed

    Akhter, Taslima; Islam, Md Monirul; Faisal, Shaikh Nayeem; Haque, Enamul; Minett, Andrew I; Liu, Hua Kun; Konstantinov, Konstantin; Dou, Shi Xue

    2016-01-27

    A novel flexible three-dimensional (3D) architecture of nitrogen and sulfur codoped graphene has been successfully synthesized via thermal treatment of a liquid crystalline graphene oxide-doping agent composition, followed by a soft self-assembly approach. The high temperature process turns the layer-by-layer assembly into a high surface area macro- and nanoporous free-standing material with different atomic configurations of graphene. The interconnected 3D network exhibits excellent charge capacitive performance of 305 F g(-1) (at 100 mV s(-1)), an unprecedented volumetric capacitance of 188 F cm(-3) (at 1 A g(-1)), and outstanding energy density of 28.44 Wh kg(-1) as well as cycle life of 10 000 cycles as a free-standing electrode for an aqueous electrolyte, symmetric supercapacitor device. Moreover, the resulting nitrogen/sulfur doped graphene architecture shows good electrocatalytic performance, long durability, and high selectivity when they are used as metal-free catalyst for the oxygen reduction reaction. This study demonstrates an efficient approach for the development of multifunctional as well as flexible 3D architectures for a series of heteroatom-doped graphene frameworks for modern energy storage as well as energy source applications. PMID:26725830

  10. High-performance graphene/sulphur electrodes for flexible Li-ion batteries using the low-temperature spraying method.

    PubMed

    Kumar, Pushpendra; Wu, Feng-Yu; Hu, Lung-Hao; Ali Abbas, Syed; Ming, Jun; Lin, Chia-Nan; Fang, Jason; Chu, Chih-Wei; Li, Lain-Jong

    2015-05-01

    Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (∼70% capacity retention after 250 cycles), good coulombic efficiency (∼98%) and high capacity (∼1500 mA h g(-1)) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes. PMID:25873204

  11. Taichi-inspired rigid-flexible coupling cellulose-supported solid polymer electrolyte for high-performance lithium batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Jianjun; Yue, Liping; Hu, Pu; Liu, Zhihong; Qin, Bingsheng; Zhang, Bo; Wang, Qingfu; Ding, Guoliang; Zhang, Chuanjian; Zhou, Xinhong; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

    2014-09-01

    Inspired by Taichi, we proposed rigid-flexible coupling concept and herein developed a highly promising solid polymer electrolyte comprised of poly (ethylene oxide), poly (cyano acrylate), lithium bis(oxalate)borate and robust cellulose nonwoven. Our investigation revealed that this new class solid polymer electrolyte possessed comprehensive properties in high mechanical integrity strength, sufficient ionic conductivity (3 10-4 S cm-1) at 60C and improved dimensional thermostability (up to 160C). In addition, the lithium iron phosphate (LiFePO4)/lithium (Li) cell using such solid polymer electrolyte displayed superior rate capacity (up to 6 C) and stable cycle performance at 80C. Furthermore, the LiFePO4/Li battery could also operate very well even at an elevated temperature of 160C, thus improving enhanced safety performance of lithium batteries. The use of this solid polymer electrolyte mitigates the safety risk and widens the operation temperature range of lithium batteries. Thus, this fascinating study demonstrates a proof of concept of the use of rigid-flexible coupling solid polymer electrolyte toward practical lithium battery applications with improved reliability and safety.

  12. Taichi-inspired rigid-flexible coupling cellulose-supported solid polymer electrolyte for high-performance lithium batteries.

    PubMed

    Zhang, Jianjun; Yue, Liping; Hu, Pu; Liu, Zhihong; Qin, Bingsheng; Zhang, Bo; Wang, Qingfu; Ding, Guoliang; Zhang, Chuanjian; Zhou, Xinhong; Yao, Jianhua; Cui, Guanglei; Chen, Liquan

    2014-01-01

    Inspired by Taichi, we proposed rigid-flexible coupling concept and herein developed a highly promising solid polymer electrolyte comprised of poly (ethylene oxide), poly (cyano acrylate), lithium bis(oxalate)borate and robust cellulose nonwoven. Our investigation revealed that this new class solid polymer electrolyte possessed comprehensive properties in high mechanical integrity strength, sufficient ionic conductivity (3 × 10(-4) S cm(-1)) at 60°C and improved dimensional thermostability (up to 160°C). In addition, the lithium iron phosphate (LiFePO4)/lithium (Li) cell using such solid polymer electrolyte displayed superior rate capacity (up to 6 C) and stable cycle performance at 80°C. Furthermore, the LiFePO4/Li battery could also operate very well even at an elevated temperature of 160°C, thus improving enhanced safety performance of lithium batteries. The use of this solid polymer electrolyte mitigates the safety risk and widens the operation temperature range of lithium batteries. Thus, this fascinating study demonstrates a proof of concept of the use of rigid-flexible coupling solid polymer electrolyte toward practical lithium battery applications with improved reliability and safety. PMID:25183416

  13. Flexible one-dimensional carbon-selenium composite nanofibers with superior electrochemical performance for Li-Se/Na-Se batteries

    NASA Astrophysics Data System (ADS)

    Zeng, Linchao; Wei, Xiang; Wang, Jiaqing; Jiang, Yu; Li, Weihan; Yu, Yan

    2015-05-01

    A facile strategy is developed to synthesis selenium/carbon composites (Se@CNFs-CNT) by co-heating Se powder and electrospun Polyacrylonitrile (PAN)-CNT nanofibers at 600°Cin a sealed vessel. The Se molecules are chemically bonded and physical encapsulated by carbonized PAN-CNT composite (CNFs-CNT), which leads to prevent the dissolution of polyselenide intermediates in carbonate based electrolyte. When directly used as flexible free-standing cathode material for Li-Se batteries in low cost carbonate-based electrolyte, the Se@CNFs-CNT electrode exhibits improved cyclability (517 mAh g-1 after 500 cycles at 0.5 A g-1) and rate capability (485 mAh g-1 at 1 A g-1). Moreover, when tested as sodium batteries, it maintains a reversible capacity of 410 mAh g-1 after 240 cycles at 0.5 A g-1. The superior electrochemical performance (especially at high rates) of Se@CNFs-CNT is attributed to synergistic effect of the additive of CNT, the well confine of Se in the CNFs-CNT matrix through chemical bonding and the 3D interconnected carbon nanofibers (CNFs). This simple yet efficient process thus provides a promising route towards fabrication of a variety of high performance flexible Li-Se and Na-Se batteries.

  14. Novel flexible MWCNTs@MoO2-C nanocable composites with excellent electrochemical performance for lithium ion battery anodes

    NASA Astrophysics Data System (ADS)

    Guan, Jipeng; Zhao, Liping; Xing, Chenyang; Li, Yongjin

    2015-09-01

    In this work, a novel flexible MWCNTs@MoO2-C nanocable composite for lithium ion battery anodes was fabricated by the electrospinning of homogeneously dispersed MWCNTs in a PVA/ammonium molybdate tetrahydrate solution and subsequent thermal treatment of the electrospun nanofibers. In the resulting MWCNTs@MoO2-C nanocable composite, the MoO2 nanoparticles were uniformly dispersed in amorphous carbon nanofibers that contained well-embedded MWCNTs as their cores. Compared with samples without MWCNTs, the unique nanocable composite exhibited not only a high specific capacity but also excellent cycling performance and good flexibility. It delivered a high reversible capacity of 832 mAh g-1 at a current density of 50 mA g-1 after 30 cycles. The enhanced electrochemical performance of the MWCNTs@MoO2-C nanocable composite was attributed to its novel nanocable structure ensuring not only effective contact between MoO2 and the liquid electrolyte, but also high conductivity for Li+ and e- transfer.

  15. Lightweight, Flexible, High-Performance Carbon Nanotube Cables Made by Scalable Flow Coating.

    PubMed

    Mirri, Francesca; Orloff, Nathan D; Forster, Aaron M; Ashkar, Rana; Headrick, Robert J; Bengio, E Amram; Long, Christian J; Choi, April; Luo, Yimin; Hight Walker, Angela R; Butler, Paul; Migler, Kalman B; Pasquali, Matteo

    2016-02-24

    Coaxial cables for data transmission are ubiquitous in telecommunications, aerospace, automotive, and robotics industries. Yet, the metals used to make commercial cables are unsuitably heavy and stiff. These undesirable traits are particularly problematic in aerospace applications, where weight is at a premium and flexibility is necessary to conform with the distributed layout of electronic components in satellites and aircraft. The cable outer conductor (OC) is usually the heaviest component of modern data cables; therefore, exchanging the conventional metallic OC for lower weight materials with comparable transmission characteristics is highly desirable. Carbon nanotubes (CNTs) have recently been proposed to replace the metal components in coaxial cables; however, signal attenuation was too high in prototypes produced so far. Here, we fabricate the OC of coaxial data cables by directly coating a solution of CNTs in chlorosulfonic acid (CSA) onto the cable inner dielectric. This coating has an electrical conductivity that is approximately 2 orders of magnitude greater than the best CNT OC reported in the literature to date. This high conductivity makes CNT coaxial cables an attractive alternative to commercial cables with a metal (tin-coated copper) OC, providing comparable cable attenuation and mechanical durability with a 97% lower component mass. PMID:26791337

  16. Solution chemistry of self-assembled graphene nanohybrids for high-performance flexible biosensors.

    PubMed

    Choi, Bong Gill; Park, Hoseok; Park, Tae Jung; Yang, Min Ho; Kim, Joon Sung; Jang, Sung-Yeon; Heo, Nam Su; Lee, Sang Yup; Kong, Jing; Hong, Won Hi

    2010-05-25

    We report the preparation of free-standing flexible conductive reduced graphene oxide/Nafion (RGON) hybrid films by a solution chemistry that utilizes self-assembly and directional convective-assembly. The hydrophobic backbone of Nafion provided well-defined integrated structures, on micro- and macroscales, for the construction of hybrid materials through self-assembly, while the hydrophilic sulfonate groups enabled highly stable dispersibility ( approximately 0.5 mg/mL) and long-term stability (2 months) for graphene. The geometrically interlocked morphology of RGON produced a high degree of mechanical integrity in the hybrid films, while the interpenetrating network constructed favorable conduction pathways for charge transport. Importantly, the synergistic electrochemical characteristics of RGON were attributed to high conductivity (1176 S/m), facilitated electron transfer (ET), and low interfacial resistance. Consequently, RGON films obtained the excellent figure of merit as electrochemical biosensing platforms for organophosphate (OP) detection, that is, a sensitivity of 10.7 nA/microM, detection limit of 1.37 x 10(-7) M, and response time of <3 s. In addition, the reliability of RGON biosensors was confirmed by a fatigue test of 100 bending cycles. The strategy described here provides insight into the fabrication of graphene and hybrid nanomaterials from a material perspective, as well as the design of biosensor platforms for practical device applications. PMID:20377244

  17. Performance and parameter variation of flexible organic thin film transistors in multicomponent organic sensors

    NASA Astrophysics Data System (ADS)

    Stadlober, Barbara; Fian, Alex; Haase, Anja; Kraker, Elke; Zirkl, Martin; Scheipl, Gregor; Jakopic, Georg

    2010-08-01

    Here we report on the fabrication and detailed characterization of flexible low-voltage organic thin-film transistors directly integrated with pyro- and piezoelectric sensors. The functional layer of the capacitive sensors is a ferroelectric fluoropolymer. The transistors on the other hand are based on a high-k nanocomposite gate dielectric and on pentacene as the organic semiconductor and can be operated well below 5V. It is shown, that the transistors can be fabricated on the fluororpolymer layer. Since the control of parameter spread is a very important topic in large area electronics, it was attempted to investigate the homogeneity of a significant set of devices by individual assessment of the layer composition and thickness, the pentacene morphology, the actual geometry and the electrical parameters. It turned out that starting from the measured device parameters such as layer thickness, capacitance, channel dimension, grain size and threshold voltage, the drain current can be calculated with high accuracy in a specified operation point. In addition, it is shown that the main influence on the parameter spread originates from the variations in the threshold voltage. Storage in air destroys the transistors on the long term, whereas bias stress measurements under inert conditions reveal that the interfaces are very stable.

  18. Oxygen Evolution Assisted Fabrication of Highly Loaded Carbon Nanotube/MnO2 Hybrid Films for High-Performance Flexible Pseudosupercapacitors.

    PubMed

    Chen, Hongyuan; Zeng, Sha; Chen, Minghai; Zhang, Yongyi; Zheng, Lianxi; Li, Qingwen

    2016-04-01

    To date, it has been a great challenge to design high-performance flexible energy storage devices for sufficient loading of redox species in the electrode assemblies, with well-maintained mechanical robustness and enhanced electron/ionic transport during charge/discharge cycles. An electrochemical activation strategy is demonstrated for the facile regeneration of carbon nanotube (CNT) film prepared via floating catalyst chemical vapor deposition strategy into a flexible, robust, and highly conductive hydrogel-like film, which is promising as electrode matrix for efficient loading of redox species and the fabrication of high-performance flexible pseudosupercapacitors. The strong and conductive CNT films can be effectively expanded and activated by electrochemical anodic oxygen evolution reaction, presenting greatly enhanced internal space and surface wettability with well-maintained strength, flexibility, and conductivity. The as-formed hydrogel-like film is quite favorable for electrochemical deposition of manganese dioxide (MnO2 ) with loading mass up to 93 wt% and electrode capacitance kept around 300 F g(-1) (areal capacitance of 1.2 F cm(-2) ). This hybrid film was further used to assemble a flexible symmetric pseudosupercapacitor without using any other current collectors and conductive additives. The assembled flexible supercapacitors exhibited good rate performance, with the areal capacitance of more than 300 mF cm(-2) , much superior to other reported MnO2 based flexible thin-film supercapacitors. PMID:26929042

  19. 76 FR 67018 - Notice to Manufacturers of Airport In-Pavement Stationary Runway Weather Information Systems

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-28

    ... Federal Aviation Administration Notice to Manufacturers of Airport In-Pavement Stationary Runway Weather... of In-Pavement Stationary Runway Weather Information Systems. SUMMARY: Projects funded under the... Active or Passive In- Pavement Stationary Runway Weather Information Systems that meet the...

  20. Ionically conducting PVA-LiClO4 gel electrolyte for high performance flexible solid state supercapacitors.

    PubMed

    Chodankar, Nilesh R; Dubal, Deepak P; Lokhande, Abhishek C; Lokhande, Chandrakant D

    2015-12-15

    The synthesis of polymer gel electrolyte having high ionic conductivity, excellent compatibility with active electrode material, mechanical tractability and long life is crucial to obtain majestic electrochemical performance for flexible solid state supercapacitors (FSS-SCs). Our present work describes effect of different polymers gel electrolytes on electrochemical properties of MnO2 based FSS-SCs device. It is revealed that, MnO2-FSS-SCs with polyvinyl alcohol (PVA)-Lithium perchlorate (LiClO4) gel electrolyte demonstrate excellent electrochemical features such as maximum operating potential window (1.2V), specific capacitance of 112Fg(-1) and energy density of 15Whkg(-1) with extended cycling stability up to 2500CV cycles. Moreover, the calendar life suggests negligible decrease in the electrochemical performance of MnO2-FSS-SCs after 20days. PMID:26397234

  1. High-performance flexible ultraviolet photoconductors based on solution-processed ultrathin ZnO/Au nanoparticle composite films

    NASA Astrophysics Data System (ADS)

    Jin, Zhiwen; Gao, Liang; Zhou, Qing; Wang, Jizheng

    2014-03-01

    Transparent ultraviolet (UV) ZnO thin film photoconductors are expected to have great applications in environmental monitoring, large-area displays, and optical communications, and they have drawn enormous interests in recent years. However, at present their performances are not satisfactory: the responsivity R (a parameter characterizing the sensitivity of the device to light) is not high (<1.0 × 103 AW-1), and the transparency T is not high either (<80%). Realizing high R and high T remains a big challenge today. In this paper, by employing solution-processed ultrathin ZnO/Au nanoparticle composite films, R as high as 1.51 × 105 AW-1 and T of over 90% are achieved. High values for detectivity D* and linear dynamic range LDR are also obtained, which are 2.05 × 1015 Jones and 60 dB, respectively. Moreover, such high-performance devices can be fabricated on flexible PET (polyethylene terephthalate) substrates.

  2. Chemically doped three-dimensional porous graphene monoliths for high-performance flexible field emitters

    NASA Astrophysics Data System (ADS)

    Kim, Ho Young; Jeong, Sooyeon; Jeong, Seung Yol; Baeg, Kang-Jun; Han, Joong Tark; Jeong, Mun Seok; Lee, Geon-Woong; Jeong, Hee Jin

    2015-03-01

    Despite the recent progress in the fabrication of field emitters based on graphene nanosheets, their morphological and electrical properties, which affect their degree of field enhancement as well as the electron tunnelling barrier height, should be controlled to allow for better field-emission properties. Here we report a method that allows the synthesis of graphene-based emitters with a high field-enhancement factor and a low work function. The method involves forming monolithic three-dimensional (3D) graphene structures by freeze-drying of a highly concentrated graphene paste and subsequent work-function engineering by chemical doping. Graphene structures with vertically aligned edges were successfully fabricated by the freeze-drying process. Furthermore, their number density could be controlled by varying the composition of the graphene paste. Al- and Au-doped 3D graphene emitters were fabricated by introducing the corresponding dopant solutions into the graphene sheets. The resulting field-emission characteristics of the resulting emitters are discussed. The synthesized 3D graphene emitters were highly flexible, maintaining their field-emission properties even when bent at large angles. This is attributed to the high crystallinity and emitter density and good chemical stability of the 3D graphene emitters, as well as to the strong interactions between the 3D graphene emitters and the substrate.Despite the recent progress in the fabrication of field emitters based on graphene nanosheets, their morphological and electrical properties, which affect their degree of field enhancement as well as the electron tunnelling barrier height, should be controlled to allow for better field-emission properties. Here we report a method that allows the synthesis of graphene-based emitters with a high field-enhancement factor and a low work function. The method involves forming monolithic three-dimensional (3D) graphene structures by freeze-drying of a highly concentrated graphene paste and subsequent work-function engineering by chemical doping. Graphene structures with vertically aligned edges were successfully fabricated by the freeze-drying process. Furthermore, their number density could be controlled by varying the composition of the graphene paste. Al- and Au-doped 3D graphene emitters were fabricated by introducing the corresponding dopant solutions into the graphene sheets. The resulting field-emission characteristics of the resulting emitters are discussed. The synthesized 3D graphene emitters were highly flexible, maintaining their field-emission properties even when bent at large angles. This is attributed to the high crystallinity and emitter density and good chemical stability of the 3D graphene emitters, as well as to the strong interactions between the 3D graphene emitters and the substrate. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07189a

  3. Hot in-place recycling of asphalt pavements. Master's thesis

    SciTech Connect

    Dowdy, M.L.

    1987-08-04

    The purpose of this report is to identify factors to consider in selecting a hot in-place recycling project for asphalt pavements. This report discusses the different types of recycling processes and several selected hot in-place recycling processes that are becoming so popular today. The types of asphalt pavement distress and their causes are discussed to provide a working knowledge of possible applications for this process. Discussions on project selection, design, and construction considerations will also provide an awareness of considerations relative to this type of asphalt-pavement rehabilitation. An understanding of these topics will be helpful when selecting hot in-place recycling. The information that this report is based upon was obtained from various sources. A literature search included technical reports, periodicals, and advertisements. Personal contact was made in the form of interviews with a number of representatives in the industry and on site inspection of Cutler Repaving, Inc. and Remixer Contracting Co., Inc. operations.

  4. An algorithm for pavement crack detection based on multiscale space

    NASA Astrophysics Data System (ADS)

    Liu, Xiang-long; Li, Qing-quan

    2006-10-01

    Conventional human-visual and manual field pavement crack detection method and approaches are very costly, time-consuming, dangerous, labor-intensive and subjective. They possess various drawbacks such as having a high degree of variability of the measure results, being unable to provide meaningful quantitative information and almost always leading to inconsistencies in crack details over space and across evaluation, and with long-periodic measurement. With the development of the public transportation and the growth of the Material Flow System, the conventional method can far from meet the demands of it, thereby, the automatic pavement state data gathering and data analyzing system come to the focus of the vocation's attention, and developments in computer technology, digital image acquisition, image processing and multi-sensors technology made the system possible, but the complexity of the image processing always made the data processing and data analyzing come to the bottle-neck of the whole system. According to the above description, a robust and high-efficient parallel pavement crack detection algorithm based on Multi-Scale Space is proposed in this paper. The proposed method is based on the facts that: (1) the crack pixels in pavement images are darker than their surroundings and continuous; (2) the threshold values of gray-level pavement images are strongly related with the mean value and standard deviation of the pixel-grey intensities. The Multi-Scale Space method is used to improve the data processing speed and minimize the effectiveness caused by image noise. Experiment results demonstrate that the advantages are remarkable: (1) it can correctly discover tiny cracks, even from very noise pavement image; (2) the efficiency and accuracy of the proposed algorithm are superior; (3) its application-dependent nature can simplify the design of the entire system.

  5. Impact of compressed natural gas fueled buses on street pavements

    SciTech Connect

    Yang, D.; Harrison, R.

    1995-07-01

    Capital Metro, the Ausin, Texas transit authority, is currently evaluating a number of CNG fueled buses. As part of the U.S. DOT Region Six University Transportation Centers Program (UTCP), a study was instigated into the scale of incremental pavement consumption associated with the operation of these buses. The study suggests that replacing current vehicles with CNG powered models utilizing aluminum storage tanks would raise average network equivalent single rehabilitation costs across the network of over four percent. Finally, it recommends that full cost study be undertaken with evaluation of the adoption of alternative bus fuels - which includes pavement and environmental impacts.

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

    USGS Publications Warehouse

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

    2006-01-01

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

  7. Performance Boosting of Flexible ZnO UV Sensors with Rational Designed Absorbing Antireflection Layer and Humectant Encapsulation.

    PubMed

    Zhang, Heng; Hu, Youfan; Wang, Zongpeng; Fang, Zheyu; Peng, Lian-Mao

    2016-01-13

    Flexible ZnO thin film UV sensors with 3 orders of magnitude improvement in sensitivity and 2 orders of magnitude acceleration in speed are realized via light absorption efficiency enhancement and surface encapsulation. Devices are constructed on polyethylene substrate incorporating morphology controlled ZnO nanorod arrays (NRAs) as absorbing antireflection layers. By adjusting the morphology of ZnO NRAs, the light absorptance exceeds 99% through effectively trapping incident photons. As a result, the sensitivity of the UV sensor reaches 109 000. Moreover, a mechanism of competitive chemisorption between O2 and H2O at oxygen vacancy sites is proposed to explain the phenomenon of the speed acceleration in moist environment. A new approach of humectant encapsulation is used to make H2O participant rapid processes dominant for speed acceleration. Two orders of magnitude speed enhancement in reset time is achieved by polyethylene glycol encapsulation. After a total 3000 cycles bending test, the decay in the responsivity of UV sensor is within 20%, indicating good mechanical stability. All these results not only demonstrate a simple, effective and scalable approach to fabricate high sensitive and fast response flexible ZnO UV sensors, but also provide meaningful references for performance boosting of photoelectronic devices based on other oxide semiconductors. PMID:26652032

  8. Self-poled transparent and flexible UV light-emitting cerium complex-PVDF composite: a high-performance nanogenerator.

    PubMed

    Garain, Samiran; Sinha, Tridib Kumar; Adhikary, Prakriti; Henkel, Karsten; Sen, Shrabanee; Ram, Shanker; Sinha, Chittaranjan; Schmeißer, Dieter; Mandal, Dipankar

    2015-01-21

    Cerium(III)-N,N-dimethylformamide-bisulfate [Ce(DMF)(HSO4)3] complex is doped into poly(vinylidene fluoride) (PVDF) to induce a higher yield (99%) of the electroactive phases (β- and γ-phases) of PVDF. A remarkable enhancement of the output voltage (∼32 V) of a nanogenerator (NG) based on a nonelectrically poled cerium(III) complex containing PVDF composite film is achieved by simple repeated human finger imparting, whereas neat PVDF does not show this kind of behavior. This high electrical output resembles the generation of self-poled electroactive β-phase in PVDF due to the electrostatic interactions between the fluoride of PVDF and the surface-active positive charge cloud of the cerium complex via H-bonding and/or bipolar interaction among the opposite poles of cerium complex and PVDF, respectively. The capacitor charging capability of the flexible NG promises its applicability as piezoelectric-based energy harvester. The cerium(III) complex doped PVDF composite film exhibit an intense photoluminescence in the UV region, which might be due to a participation of electron cloud from negative pole of bipolarized PVDF. This fact may open a new area for prospective development of high-performance energy-saving flexible solid-state UV light emitters. PMID:25523039

  9. Multiwalled carbon nanotube/polydimethylsiloxane composite films as high performance flexible electric heating elements

    SciTech Connect

    Yan, Jing; Jeong, Young Gyu

    2014-08-04

    High performance elastomeric electric heating elements were prepared by incorporating various contents of pristine multiwalled carbon nanotube (MWCNT) in polydimethylsiloxane (PDMS) matrix by using an efficient solution-casting and curing technique. The pristine MWCNTs were identified to be uniformly dispersed in the PDMS matrix and the electrical percolation of MWCNTs was evaluated to be at ∼0.27 wt. %, where the electrical resistivity of the MWCNT/PDMS composite films dropped remarkably. Accordingly, the composite films with higher MWCNT contents above 0.3 wt. % exhibit excellent electric heating performance in terms of temperature response rapidity and electric energy efficiency at constant applied voltages. In addition, the composite films, which were thermally stable up to 250 °C, showed excellent heating-cooling cyclic performance, which was associated with operational stability in actual electric heating applications.

  10. Thermal conductance of and heat generation in tire-pavement interface and effect on aircraft braking

    NASA Technical Reports Server (NTRS)

    Miller, C. D.

    1976-01-01

    A finite-difference analysis was performed on temperature records obtained from a free rolling automotive tire and from pavement surface. A high thermal contact conductance between tire and asphalt was found on a statistical basis. Average slip due to squirming between tire and asphalt was about 1.5 mm. Consequent friction heat was estimated as 64 percent of total power absorbed by bias-ply, belted tire. Extrapolation of results to aircraft tire indicates potential braking improvement by even moderate increase of heat absorbing capacity of runway surface.

  11. Flexibly Global? Performing Culture and Identity in an Age of Uncertainty

    ERIC Educational Resources Information Center

    Giardina, Michael D.

    2009-01-01

    Presented as a symbolic interactive messy performance text, Michael Giardina sutures himself into and through the landscape of global social relations, including his own interpretive interactions of disconnection and reconnection with place, home, and nation. In so doing, and in these collages of lived textuality, he examines the complex,…

  12. Deep Thinking Increases Task-Set Shielding and Reduces Shifting Flexibility in Dual-Task Performance

    ERIC Educational Resources Information Center

    Fischer, Rico; Hommel, Bernhard

    2012-01-01

    Performing two tasks concurrently is difficult, which has been taken to imply the existence of a structural processing bottleneck. Here we sought to assess whether and to what degree one's multitasking abilities depend on the cognitive-control style one engages in. Participants were primed with creativity tasks that either called for divergent…

  13. Deep Thinking Increases Task-Set Shielding and Reduces Shifting Flexibility in Dual-Task Performance

    ERIC Educational Resources Information Center

    Fischer, Rico; Hommel, Bernhard

    2012-01-01

    Performing two tasks concurrently is difficult, which has been taken to imply the existence of a structural processing bottleneck. Here we sought to assess whether and to what degree one's multitasking abilities depend on the cognitive-control style one engages in. Participants were primed with creativity tasks that either called for divergent

  14. Flexibly Global? Performing Culture and Identity in an Age of Uncertainty

    ERIC Educational Resources Information Center

    Giardina, Michael D.

    2009-01-01

    Presented as a symbolic interactive messy performance text, Michael Giardina sutures himself into and through the landscape of global social relations, including his own interpretive interactions of disconnection and reconnection with place, home, and nation. In so doing, and in these collages of lived textuality, he examines the complex,

  15. An Efficient Finite Element Framework to Assess Flexibility Performances of SMA Self-Expandable Carotid Artery Stents

    PubMed Central

    Ferraro, Mauro; Auricchio, Ferdinando; Boatti, Elisa; Scalet, Giulia; Conti, Michele; Morganti, Simone; Reali, Alessandro

    2015-01-01

    Computer-based simulations are nowadays widely exploited for the prediction of the mechanical behavior of different biomedical devices. In this aspect, structural finite element analyses (FEA) are currently the preferred computational tool to evaluate the stent response under bending. This work aims at developing a computational framework based on linear and higher order FEA to evaluate the flexibility of self-expandable carotid artery stents. In particular, numerical simulations involving large deformations and inelastic shape memory alloy constitutive modeling are performed, and the results suggest that the employment of higher order FEA allows accurately representing the computational domain and getting a better approximation of the solution with a widely-reduced number of degrees of freedom with respect to linear FEA. Moreover, when buckling phenomena occur, higher order FEA presents a superior capability of reproducing the nonlinear local effects related to buckling phenomena. PMID:26184329

  16. Low-voltage flexible organic electronics based on high-performance sol-gel titanium dioxide dielectric.

    PubMed

    Sung, Sujin; Park, Sungjun; Lee, Won-June; Son, Jongho; Kim, Chang-Hyun; Kim, Yoonhee; Noh, Do Young; Yoon, Myung-Han

    2015-04-15

    In this letter, we report that high-performance insulating films can be generated by judicious control over the microstructure of sol-gel-processed titanium dioxide (TiO2) films, typically known as wide-bandgap semiconductors. The resultant device made of 23 nm-thick TiO2 dielectric layer exhibits a low leakage current density of ∼1 × 10(-7) A cm(-2) at 2 V and a large areal capacitance of 560 nF cm(-2) with the corresponding dielectric constant of 27. Finally, low-voltage flexible organic thin-film transistors were successfully demonstrated by incorporating this versatile solution-processed oxide dielectric material into pentacene transistors on polyimide substrates. PMID:25751669

  17. High-performance graphene/sulphur electrodes for flexible Li-ion batteries using the low-temperature spraying method

    NASA Astrophysics Data System (ADS)

    Kumar, Pushpendra; Wu, Feng-Yu; Hu, Lung-Hao; Ali Abbas, Syed; Ming, Jun; Lin, Chia-Nan; Fang, Jason; Chu, Chih-Wei; Li, Lain-Jong

    2015-04-01

    Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (~70% capacity retention after 250 cycles), good coulombic efficiency (~98%) and high capacity (~1500 mA h g-1) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes.Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (~70% capacity retention after 250 cycles), good coulombic efficiency (~98%) and high capacity (~1500 mA h g-1) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00885a

  18. An Efficient Finite Element Framework to Assess Flexibility Performances of SMA Self-Expandable Carotid Artery Stents.

    PubMed

    Ferraro, Mauro; Auricchio, Ferdinando; Boatti, Elisa; Scalet, Giulia; Conti, Michele; Morganti, Simone; Reali, Alessandro

    2015-01-01

    Computer-based simulations are nowadays widely exploited for the prediction of the mechanical behavior of different biomedical devices. In this aspect, structural finite element analyses (FEA) are currently the preferred computational tool to evaluate the stent response under bending. This work aims at developing a computational framework based on linear and higher order FEA to evaluate the flexibility of self-expandable carotid artery stents. In particular, numerical simulations involving large deformations and inelastic shape memory alloy constitutive modeling are performed, and the results suggest that the employment of higher order FEA allows accurately representing the computational domain and getting a better approximation of the solution with a widely-reduced number of degrees of freedom with respect to linear FEA. Moreover, when buckling phenomena occur, higher order FEA presents a superior capability of reproducing the nonlinear local effects related to buckling phenomena. PMID:26184329

  19. Assessing the improved performance of freestanding, flexible graphene and carbon nanotube hybrid foams for lithium ion battery anodes.

    PubMed

    Cohn, Adam P; Oakes, Landon; Carter, Rachel; Chatterjee, Shahana; Westover, Andrew S; Share, Keith; Pint, Cary L

    2014-05-01

    We demonstrate the fabrication of three-dimensional freestanding foams of hybrid graphene-single-walled carbon nanotube nanomanufactured materials with reversible capacities of 2640 mA h g(-1) at 0.186 A g(-1) and 236 mA h g(-1) at 27.9 A g(-1). The Li storage behavior of this material is compared against other nanostructures in similar flexible foam platforms including graphene, ultra-thin graphite, and single-walled carbon nanotubes (SWNTs), and we elucidate the improved hybrid material performance due to the decoupling of lithium storage reaction energetics dictated by the SWNTs from the total storage capacity of the hybrid material. This work demonstrates a route to develop mechanically robust all-carbon electrodes with the potential for reversible Li-ion storage capacity approaching silicon, power capability of the best supercapacitors, and based on a material simultaneously usable as a charge collector and anode. PMID:24647668

  20. High-Performance Flexible Solid-State Supercapacitor with an Extended Nanoregime Interface through in Situ Polymer Electrolyte Generation.

    PubMed

    Anothumakkool, Bihag; Torris A T, Arun; Veeliyath, Sajna; Vijayakumar, Vidyanand; Badiger, Manohar V; Kurungot, Sreekumar

    2016-01-20

    Here, we report an efficient strategy by which a significantly enhanced electrode-electrolyte interface in an electrode for supercapacitor application could be accomplished by allowing in situ polymer gel electrolyte generation inside the nanopores of the electrodes. This unique and highly efficient strategy could be conceived by judiciously maintaining ultraviolet-triggered polymerization of a monomer mixture in the presence of a high-surface-area porous carbon. The method is very simple and scalable, and a prototype, flexible solid-state supercapacitor could even be demonstrated in an encapsulation-free condition by using the commercial-grade electrodes (thickness = 150 μm, area = 12 cm(2), and mass loading = 7.3 mg/cm(2)). This prototype device shows a capacitance of 130 F/g at a substantially reduced internal resistance of 0.5 Ω and a high capacitance retention of 84% after 32000 cycles. The present system is found to be clearly outperforming a similar system derived by using the conventional polymer electrolyte (PVA-H3PO4 as the electrolyte), which could display a capacitance of only 95 F/g, and this value falls to nearly 50% in just 5000 cycles. The superior performance in the present case is credited primarily to the excellent interface formation of the in situ generated polymer electrolyte inside the nanopores of the electrode. Further, the interpenetrated nature of the polymer also helps the device to show a low electron spin resonance and power rate and, most importantly, excellent shelf-life in the unsealed flexible conditions. Because the nature of the electrode-electrolyte interface is the major performance-determining factor in the case of many electrochemical energy storage/conversion systems, along with the supercapacitors, the developed process can also find applications in preparing electrodes for the devices such as lithium-ion batteries, metal-air batteries, polymer electrolyte membrane fuel cells, etc. PMID:26697922

  1. DEVELOPMENT OF A HYDROPHOBIC SUBSTANCE TO MITIGATE PAVEMENT ICE ADHESION

    EPA Science Inventory

    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...

  2. Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates.

    PubMed

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

    2010-05-01

    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

  3. Alternative aircraft loading index for pavement structural analysis

    SciTech Connect

    Loizos, A.; Charonitis, G.

    1999-05-01

    The most common practical way to simplify the structural analysis of airfield pavements is the use of equivalent single wheel load models instead of the actual gear of the aircrafts. As the accuracy and reliability of these models strongly affects the design and evaluation of airfield pavements, there is considerable need to investigate both system approaches. The first one, which uses a constant value for the pressure while the radius is variable, is currently under use by the aircraft classification number-pavement classification number method of the International Civil Aviation Organization, but despite this fact it proved to be inadequate to express the aircraft loading in many situations. On the contrary, according to this study, the second model, which has a constant value for the radius while the pressure varies, is more reliable, and it can be an interesting alternative. Thus, based on this model, an aircraft loading index is introduced, which aims to be a simple and reliable factor for expressing the severity of the loading of the aircrafts and a utility for several matters related to the airfield pavement applications.

  4. The Edison Environmental Center Permeable Pavement Site - slides

    EPA Science Inventory

    This is a presentation for a second Community Outreach Event called "Chemistry Works!" at West Windsor Public Library on Saturday, November 5th. It will review the permeable pavement research project at the Edison Environmental center. Besides slide persentation, two demo units w...

  5. AREA UNDER TREES BETWEEN HOUSES AND EDGE OF PAVEMENT ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    AREA UNDER TREES BETWEEN HOUSES AND EDGE OF PAVEMENT ON THE EAST SIDE OF SOUTH JEFFERSON STREET FROM SOUTHEAST CORNER OF INTERSECTION OF SOUTH JEFFERSON STREET AND HIGHLAND AVENUE - South Albany Historic District, Bounded by South Jefferson Street, Highland Avenue & Whitney Avenue, Albany, Dougherty County, GA

  6. Nitrogen Transformations in Three Types of Permeable Pavement

    EPA Science Inventory

    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...

  7. Infiltration performance of engineered surfaces commonly used for distributed stormwater management

    NASA Astrophysics Data System (ADS)

    Valinski, Nicholas A.

    Engineered porous media are commonly used in low impact development (LID) structures to mitigate excess stormwater in urban environments. Differences in infiltrability of these LID systems arise from the wide variety of materials used to create porous surfaces and subsequent maintenance, debris loading, and physical damage. In this study, infiltration capacity of six common materials was tested by multiple replicate experiments with automated mini-disk infiltrometers. The tested materials included porous asphalt, porous concrete, porous brick pavers, flexible porous pavement, engineered soils, and native soils. Porous asphalt, large porous brick pavers, and curb cutout rain gardens showed the greatest infiltration rates. Most engineered porous pavements and soils performed better than the native silt loam soils. Infiltration performance was found to be related more to site design and environmental factors than material choice. Sediment trap zones in both pavements and engineered soil rain gardens were found to be beneficial to the whole site performance. Winter chloride application had a large negative impact on poured in place concrete, making it a poor choice for heavily salted areas.

  8. Infiltration performance of engineered surfaces commonly used for distributed stormwater management.

    PubMed

    Valinski, N A; Chandler, D G

    2015-09-01

    Engineered porous media are commonly used in low impact development (LID) structures to mitigate excess stormwater in urban environments. Differences in infiltrability of these LID systems arise from the wide variety of materials used to create porous surfaces and subsequent maintenance, debris loading, and physical damage. In this study, the infiltration capacity of six common materials was tested by multiple replicate experiments with automated mini-disk infiltrometers. The tested materials included porous asphalt, porous concrete, porous brick pavers, flexible porous pavement, engineered soils, and native soils. Porous asphalt, large porous brick pavers, and curb cutout rain gardens showed the greatest infiltration rates. Most engineered porous pavements and soils performed better than the native silt loam soils. Infiltration performance was found to be related more to site design and environmental factors than material choice. Sediment trap zones in both pavements and engineered soil rain gardens were found to be beneficial to the whole site performance. Winter chloride application had a large negative impact on poured in place concrete, making it a poor choice for heavily salted areas. PMID:26140743

  9. Nutrient infiltrate concentrations from three permeable pavement types.

    PubMed

    Brown, Robert A; Borst, Michael

    2015-12-01

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m(2), lined sections that direct all infiltrate into 5.7-m(3) tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP and PC, and this was attributed to the high pH in PA infiltrate possibly causing rapid precipitation of orthophosphate with metal cations. Orthophosphate was exported from the PICP and PC, as evidenced by the significantly larger infiltrate concentrations compared with influent sources of rainwater and runoff. PMID:26348134

  10. Selection for Growth Performance in Broiler Chickens Associates with Less Diet Flexibility

    PubMed Central

    Pauwels, Jana; Coopman, Frank; Cools, An; Michiels, Joris; Fremaut, Dirk; De Smet, Stefaan; Janssens, Geert P. J.

    2015-01-01

    Global competition for high standard feed-food resources between man and livestock, such as industrial broilers, is a concerning problem. In addition, the low productivity of scavenger chickens in developing countries leaves much to be desired. Changing the ingredients, and therefore, the nutrient composition of feed intake by commercial fed as well as scavenger chickens seems like an obvious solution. In this study, the ability of four broiler chicken breeds to perform on a commercial versus a scavenger diet was tested. The four broiler breeds differed genetically in growth potential. A significant (P < 0.01) negative effect of the scavenger diet on the bodyweight of the fast growing breeds was found and this effect decreased with decreasing growth rate in the other breeds. These differences in bodyweight gain could not be explained by differences in nutrient digestibility but were caused by the lack of ability of the fast growing breeds to increase their feed intake sufficiently. PMID:26042600

  11. Solution-processed trilayer inorganic dielectric for high performance flexible organic field effect transistors

    NASA Astrophysics Data System (ADS)

    Tan, H. S.; Kulkarni, S. R.; Cahyadi, T.; Lee, P. S.; Mhaisalkar, S. G.; Kasim, J.; Shen, Z. X.; Zhu, F. R.

    2008-11-01

    High performance organic field effect transistors using a solution-processable processed trilayer sol-gel silica gate dielectric architecture fabricated on plastic substrates exhibited low driving voltages of -3.0V, high saturation mobilities of ˜3.5cm2/Vs, and on-off current ratio of 105. The enhancement in field effect mobility is attributed to improved dielectric-semiconductor interfacial morphology and increased capacitance of the tristratal dielectric. The pentacene devices displayed no signs of electrical degradation upon bending through a bending radius of 24mm, 2.27% strain. The slight increase in the drain currents upon bending strain was investigated using Raman spectroscopy, which revealed enhanced in-phase intermolecular coupling.

  12. Towards a high performance parallel library to compute fluid and flexible structures interactions

    NASA Astrophysics Data System (ADS)

    Nagar, Prateek

    LBM-IB method is useful and popular simulation technique that is adopted ubiquitously to solve Fluid-Structure interaction problems in computational fluid dynamics. These problems are known for utilizing computing resources intensively while solving mathematical equations involved in simulations. Problems involving such interactions are omnipresent, therefore, it is eminent that a faster and accurate algorithm exists for solving these equations, to reproduce a real-life model of such complex analytical problems in a shorter time period. LBM-IB being inherently parallel, proves to be an ideal candidate for developing a parallel software. This research focuses on developing a parallel software library, LBM-IB based on the algorithm proposed by [1] which is first of its kind that utilizes the high performance computing abilities of supercomputers procurable today. An initial sequential version of LBM-IB is developed that is used as a benchmark for correctness and performance evaluation of shared memory parallel versions. Two shared memory parallel versions of LBM-IB have been developed using OpenMP and Pthread library respectively. The OpenMP version is able to scale well enough, as good as 83% speedup on multicore machines for 8 cores. Based on the profiling and instrumentation done on this version, to improve the data-locality and increase the degree of parallelism, Pthread based data centric version is developed which is able to outperform the OpenMP version by 53% on manycore machines. A distributed version using the MPI interfaces on top of the cube based Pthread version has also been designed to be used by extreme scale distributed memory manycore systems.

  13. High performance printed N and P-type OTFTs enabling digital and analog complementary circuits on flexible plastic substrate

    NASA Astrophysics Data System (ADS)

    Jacob, S.; Abdinia, S.; Benwadih, M.; Bablet, J.; Chartier, I.; Gwoziecki, R.; Cantatore, E.; van Roermund, A. H. M.; Maddiona, L.; Tramontana, F.; Maiellaro, G.; Mariucci, L.; Rapisarda, M.; Palmisano, G.; Coppard, R.

    2013-06-01

    This paper presents a printed organic complementary technology on flexible plastic substrate with high performance N and P-type Organic Thin Film Transistors (OTFTs), based on small-molecule organic semiconductors in solution. Challenges related to the integration of both OTFT types in a common complementary flow are addressed, showing the importance of surface treatments. Stability on single devices and on an elementary complementary digital circuit (ring oscillator) is studied, demonstrating that a robust and reliable flow with high electrical performances can be established for printed organic devices. These devices are used to manufacture several analog and digital building blocks. The design is carried out using a model specifically developed for this technology, and taking into account the parametric variability. High-frequency measurements of printed envelope detectors show improved speed performance, resulting from the high mobility of the OTFTs. In addition, a compact dynamic flip-flop and a low-offset comparator are demonstrated, thanks to availability of both n-type and p-type OTFTs in the technology. Measurement results are in good agreement with the simulations. The circuits presented establish a complete library of building blocks for the realization of a printed RFID tag.

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

    NASA Astrophysics Data System (ADS)

    Shahini Shamsabadi, Salar

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

  15. Asphalt additives in thick hot mixed asphalt-concrete pavements. Research report (Interim), Sep 86-Oct 90

    SciTech Connect

    Button, J.W.; Prapnnachari, S.

    1991-01-01

    Asphalt concrete field test pavements were placed in District 19 north of Texarkana on US-59/71 in 1987 and 1988 to evaluate the ability of certain asphalt additives to enhance resistance to cracking and rutting. Two 10-inch thick and 0.9 mile (approx.) long test pavements and a similar untreated control section were constructed in the northbound and southbound lanes for a total of 6 field trials. Asphalt additives were incorporated in both the 8-inch base and the overlying 2-inch surface layers. The additives evaluated included Goodyear LPF 5812, Chemkrete-CTI 102, Exxon Polybilt 102, and Styrelf 13. Samples of paving materials including aggregates, asphalts, compacted mixes, and pavement cores were collected, conveyed to the laboratory, and tested to provide detailed documentation of their properties. Tests included rheological properties of the binders before and after artificial aging, characterization of aggregate, Hveem and Marshall stability, stiffness as a function of temperature, tensile properties before and after moisture conditioning and artificial aging, air void content, creep, and permanent deformation. Field tests and visual evaluations have been conducted to objectively evaluate field performance. Results of these tests are reported herein. Within 6 months after construction of the base layers and prior to placement of the surface course, the Chemkrete modified base became severely cracked. As a result, the surface mix placed on this base section was treated with Goodyear latex rather than Chemkrete. All other modified pavements and the control section have performed well and exhibited essentially equivalent performance after 2 1/2 years in service.

  16. Predicting physical clogging of porous and permeable pavements

    NASA Astrophysics Data System (ADS)

    Yong, C. F.; McCarthy, D. T.; Deletic, A.

    2013-02-01

    SummaryPorous pavements are easily retrofitted, and effective in improving water quality and hydrology, but prone to clogging. Despite being a major determinant in the lifespan of porous pavements, there is limited information on the physical clogging processes through these systems. The aim of this study was to understand the main physical processes that govern physical clogging and develop a simple black-box model that predicts physical clogging. The key variables that were hypothesised to influence clogging were pavement design and climate characteristics. Two compressed time scale laboratory experiments were conducted over 3 years on three common porous pavement types; monolithic porous asphalt, modular Hydrapave and monolithic Permapave. Pavement design was found to be an important role in clogging. Permapave did not clog even after 26 years of operation in simulated sub-tropical Brisbane (Australia) climate while porous asphalt and Hydrapave clogged after just 12 years, from surface clogging and geotextile clogging, respectively. Each system was tested using two different dosing patterns: (1) continual wetting with no dry periods and (2) variable inflow rates with drying periods (i.e. representing more natural conditions). The latter dosing method approximately doubled the lifespan of all systems suggesting the influence of climate conditions on clogging. Clogging was found to be highly correlated with cumulative volume and flow rate. A simple black-box regression model that predicts physical clogging was developed as a function of cumulative volume and Brisbane climatic conditions. However it is very likely that the shape of this regression is general, and that it could be calibrated for different climates in the future.

  17. Robotic vehicle mobility and task performance: A flexible control modality for manned systems

    NASA Technical Reports Server (NTRS)

    Eldredge, Frederick

    1994-01-01

    In the early 1980's, a number of concepts were developed for applying robotics to ground systems. The majority of these early application concepts envisioned robotics technology embedded in dedicated unmanned systems; i.e., unmanned systems with no provision for direct manned control of the platform. Although these concepts offered advantages peculiar to platforms designed from the outset exclusively for unmanned operation--i.e., no crew compartment--their findings would require costs and support for a new class of unmanned systems. The current era of reduced budgets and increasing focus on rapid force projection has created new opportunities to examine the value of an alternative concept: the use of existing manned platforms with an ability to quickly shift from normal manned operation to unmanned should a particularly harzardous situation arise. The author of this paper addresses the evolution of robotic vehicle concepts and technology testbeds from exclusively unmanned systems to a variety of 'optionally manned' systems which have been designed with minimum intrusion actuator and control equipment to minimize degradation of vehicle performance in manned modes of operation.

  18. Comparative Occupational Survey of Civilian and Military Members in the Pavements Maintenance and Construction Equipment Operator Specialties. Final Report for Period 1 October 1975-30 October 1977.

    ERIC Educational Resources Information Center

    Cowan, Douglas K.

    A study was conducted to analyze and compare the job performance of civil service and military pavements maintenance workers and construction equipment operators. A military sample of 2,675 and a civilian sample of 1,974 were surveyed by means of a job inventory checklist and relative time spent rating method. Of the three job types that were…

  19. Effects of a short proprioceptive neuromuscular facilitation stretching bout on quadriceps neuromuscular function, flexibility, and vertical jump performance.

    PubMed

    Place, Nicolas; Blum, Yannick; Armand, Stéphane; Maffiuletti, Nicola A; Behm, David G

    2013-02-01

    The inclusion of relatively long bouts of stretching (repeated static stretches of ∼30 seconds) in the warm-up is usually associated with a drop in muscle performance. The purpose of this study was to assess the effect of a novel self-administered proprioceptive neuromuscular facilitation (PNF) paradigm with short periods of stretching and contraction on quadriceps neuromuscular function, vertical jump performance, and articular range of motion (ROM). Twelve healthy men (age: 27.7 ± 7.3 years, height: 178.4 ± 10.4 cm, weight: 73.8 ± 16.9 kg) volunteered to participate in a PNF session and a control session separated by 2-7 days. The PNF stretching lasted 2 minutes and consisted of 4 sets of 5-second isometric hamstring contraction immediately followed by 5 seconds of passive static stretch of the quadriceps immediately followed by 5 seconds isometric quadriceps contraction for each leg. For the control session, the participants were asked to walk at a comfortable speed for 2 minutes. Active ROM of knee flexion, vertical jump performance, and quadriceps neuromuscular function were tested before, immediately after, and 15 minutes after the intervention. The PNF stretching procedure did not affect ROM, squat jump, and countermovement jump performances. Accordingly, we did not observe any change in maximal voluntary contraction force, voluntary activation level, M-wave and twitch contractile properties that could be attributed to PNF stretching. The present self-administered PNF stretching of the quadriceps with short (5-second) stretches is not recommended before sports where flexibility is mandatory for performance. PMID:22505131

  20. The use of fluvial and marine sediments in the formulation of roller compacted concrete for use in pavements.

    PubMed

    Zdiri, M; Abriakb, N E; Ben Ouezdoua, M; Neji, J

    2009-07-01

    In the manufacture of Roller Compacted Concrete (RCC) used for pavement materials, various types of aggregates are used, such as crushed and rolled limestone or siliceous aggregates. The main objective is always to reach the maximum compactness to achieve higher mechanical performances. In the present work, fluvial and marine sediments, resulting from the dredging of harbours and rivers, were introduced as aggregates in the preparation of RCC for pavement construction, with a view to improving the mechanical strength of the RCC. This study included a granulometric, mineralogical and chemical characterization of the aggregates. The work also contains a mechanical characterization of the resulting material. The objective of the study was to find a resistant RCC, by developing materials such as sediments that are often classified as a waste and where their storage is harmful to the environment. The mechanical strengths obtained showed the profitability of using a Roller Compacted Concrete containing sediments. PMID:19705664

  1. Enhancing the resolution of gpr spectra for pavement engineering applications

    NASA Astrophysics Data System (ADS)

    Benedetto, F.; Benedetto, A.

    2012-04-01

    Ground Penetrating Radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. This non-destructive method uses electromagnetic radiation and detects the reflected signals from subsurface structures. It can detect objects, changes in material, and voids and cracks. GPR has many applications in a number of fields. In the field of civil engineering one of the most advanced technologies used for road pavement monitoring is based on the deployment of advanced GPR systems. One of the most relevant causes of road pavement damage is often referable to water intrusion in structural layers. In this context, GPR has been recently proposed as a method to estimate moisture content in a porous medium without preventive calibration. Hence, the development of methods to obtain an estimate of the moisture content is a crucial research field involving economic, social and strategic aspects in road safety for a great number of public and private Agencies. In particular, a recent new approach was proposed to estimate moisture content in a porous medium basing on the theory of Rayleigh scattering, showing a shift of the frequency peak of the GPR spectrum towards lower frequencies as the moisture content increases in the soil. The weakness characterizing this approach is represented by the needs of high resolution signals, whereas GPR spectra are affected by low resolution. Hence, the rising requirement for high resolution leads to specific demands for improved prediction methods. Recently, a new technique combining the response of the conventional fast Fourier transform (FFT, well known for its high-precision receiving signal level) with that of the MUSIC (multiple signal classification) algorithm, well known for its super-resolution capacity has been proposed. This combined method has been proved to obtain a high precision level in quantifying the shift of the frequency peak of the GPR spectrum. This combined method can perform a reliable coarse estimate of the (abscissa of the) frequency peak. Unfortunately, whereas resolution affecting the GPR spectra has been enhanced, we still need a sensible increasing of the moisture content to appreciate a visible frequency shift. Hence, sub-sample resolution techniques are needed to obtain a resolution better than the sample period. Addressing some of these issues, this work proposes a sub-sample resolution technique exploiting a fast parabolic interpolator, running on three samples of the GPR spectrum in the neighborhood of the frequency peak (i.e. the coarse estimation). More in details, the new detector searches for the (abscissa of the) vertex of the parabola fitted over three GPR samples: the coarse estimate of the frequency peak, and one sample before and after this estimation. The rationale behind the new fast parabolic approach is as follows. We expect the method to obtain a finer estimation of the (abscissa of the) frequency peak because we are now interpolating a parabola in the neighborhood of the same maximum (i.e the coarse estimate), but with a narrow variance thus increasing the estimation accuracy. No noteworthy increase of computational complexity and processing throughput is required to implement the new approach. In fact, near the totality of the amount of the required computation is due to the former stage (i.e. FFT and/or MUSIC implementation to evaluate the coarse estimate of the frequency peak), and the latter logic (i.e. the interpolation function) is negligible from implementation and computational point of view. Experimental results confirm the effectiveness of the proposed approach to evidence and quantify moisture content in soil. In fact, the proposed sub-sample super resolution technique can resolve a frequency shift in the GPR spectrum even for a corresponding amount of moisture less than 2-3%.

  2. High-performance flexible thin-film transistors fabricated using print-transferrable polycrystalline silicon membranes on a plastic substrate

    NASA Astrophysics Data System (ADS)

    Qin, Guoxuan; Yuan, Hao-Chih; Yang, Hongjun; Zhou, Weidong; Ma, Zhenqiang

    2011-02-01

    Inexpensive polycrystalline Si (poly-Si) with large grain size is highly desirable for flexible electronics applications. However, it is very challenging to directly deposit high-quality poly-Si on plastic substrates due to processing constrictions, such as temperature tolerance and residual stress. In this paper, we present our study on poly-Si membranes that are stress free and most importantly, are transferrable to any substrate including a low-temperature polyethylene terephthalate (PET) substrate. We formed poly-Si-on-insulator by first depositing small-grain size poly-Si on an oxidized Si wafer. We then performed high-temperature annealing for recrystallization to obtain larger grain size. After selective doping on the poly-Si-on-insulator, buried oxide was etched away. By properly patterning the poly-Si layer, residual stress in the released poly-Si membranes was completely relaxed. The flat membrane topology allows the membranes to be print transferred to any substrates. High-performance TFTs were demonstrated on the transferred poly-Si membranes on a PET substrate.

  3. Designed Construction of a Graphene and Iron Oxide Freestanding Electrode with Enhanced Flexible Energy-Storage Performance.

    PubMed

    Li, Meng; Pan, Feng; Choo, Eugene Shi Guang; Lv, Yunbo; Chen, Yu; Xue, Junmin

    2016-03-23

    In this work, a bendable graphene@iron oxide hybrid film (GFeF) electrode was fabricated through a filtration-assisted self-assembly method. Morphological characterization of GFeF revealed a uniform distribution of iron oxide nanoparticles between graphene nanosheets. Surface chemical characterization confirmed that graphene oxide in the as-prepared hybrid film was effectively reduced after thermal reduction. The electrochemical performance of a GFeF half-cell versus Li/Li(+) exhibited high gravimetric capacity (855.2 mAh g(-1) at 0.02 A g(-1)), high volumetric capacity (1949.9 mAh cm(-3) at 0.02 A g(-1)), and superior cycling stability (93% capacitance retention after 500 cycles). On the basis of such a bendable electrode, a hybrid Li-ion supercapacitor that offers an operation voltage of 3.5 V and delivers a high energy density (129.6 Wh kg(-1)) like a Li-ion battery combined with a high power density (1870 W kg(-1)) like a supercapacitor was fabricated. In addition to the superior energy-storage capability, the as-fabricated prototype pouch cell also exhibited excellent mechanical flexibility and stable electrochemical performances under dynamic bending. The viability of such an energy-storage device provides a possible design pathway for future wearable electronics. PMID:26926985

  4. Flexible and High Performance Supercapacitors Based on NiCo2O4for Wide Temperature Range Applications

    PubMed Central

    Gupta, Ram K.; Candler, John; Palchoudhury, Soubantika; Ramasamy, Karthik; Gupta, Bipin Kumar

    2015-01-01

    Binder free nanostructured NiCo2O4 were grown using a facile hydrothermal technique. X-ray diffraction patterns confirmed the phase purity of NiCo2O4. The surface morphology and microstructure of the NiCo2O4 analyzed by scanning electron microscopy (SEM) showed flower-like morphology composed of needle-like structures. The potential application of binder free NiCo2O4 as an electrode for supercapacitor devices was investigated using electrochemical methods. The cyclic voltammograms of NiCo2O4 electrode using alkaline aqueous electrolytes showed the presence of redox peaks suggesting pseudocapacitance behavior. Quasi-solid state supercapacitor device fabricated by sandwiching two NiCo2O4 electrodes and separating them by ion transporting layer. The performance of the device was tested using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The device showed excellent flexibility and cyclic stability. The temperature dependent charge storage capacity was measured for their variable temperature applications. Specific capacitance of the device was enhanced by ~150% on raising the temperature from 20 to 60 °C. Hence, the results suggest that NiCo2O4 grown under these conditions could be a suitable material for high performance supercapacitor devices that can be operated at variable temperatures. PMID:26482921

  5. Flexible copper-stabilized sulfur-carbon nanofibers with excellent electrochemical performance for Li-S batteries

    NASA Astrophysics Data System (ADS)

    Zeng, Linchao; Jiang, Yu; Xu, Jun; Wang, Min; Li, Weihan; Yu, Yan

    2015-06-01

    By rational design, we fabricated a flexible and free-standing copper-immobilized sulfur-porous carbon nanofiber (denoted as S@PCNFs-Cu) electrode by simply impregnating sulfur into electrospun derived Cu embedded porous carbon nanofibers (PCNFs-Cu). The PCNF film with a 3D interconnected structure is used as a conducting matrix to encapsulate sulfur. In addition, the introduction of Cu leads to the formation of a chemical bond between Cu and S, preventing the dissolution of polysulfide during cycling. The micropores and mesopores of PCNF hosts provide free space to accommodate the volume change of S and polysulfide. When used as a cathode material for Li-S batteries, the S@PCNFs-Cu (S content: 52 wt%) exhibits much better electrochemical performance compared to the Cu-free S@PCNF electrode. The S@PCNFs-Cu displays high reversible capacity (680 mA h g-1 after 100 cycles at 50 mA g-1), excellent rate capability (415 mA h g-1 at 1 A g-1) and super Coulombic efficiency of 100%. This strategy of stabilizing S with a small amount of copper nanoparticles can be a very promising method to prepare free-standing cathode material for high-performance Li-S batteries.

  6. Ecological restoration and soil improvement performance of the seabuckthorn flexible dam in the Pisha Sandstone area of Northwestern China

    NASA Astrophysics Data System (ADS)

    Yang, F. S.; Cao, M. M.; Li, H. E.; Wang, X. H.; Bi, C. F.

    2014-09-01

    Soil erosion of the Pisha Sandstone area of Loess Plateau is extremely severe in China. The Pisha Sandstone is very hard when it is dry, while it is very frail when wet. The seabuckthorn flexible dam (SFD), a type of ecological engineering, was proposed to control soil erosion and meliorate soil within the Pisha Sandstone area. To assess its effectiveness and the ecological restoration and soil improvement performance, a field experiment was conducted in this area. We found the strong sediment retention capacity of the SFD is the basis of using it to restore the ecosystem. We compared some certain ecological factors and soil quality between a gully with the SFD and a gully without the SFD, including soil moisture, soil organic matter (SOM), soil nutrients (including Ammonia Nitrogen, available phosphorus and Potassium), vegetation coverage and biodiversity. The results showed that the SFD exhibits excellent performance for ecological restoration and soil improvement of this area. The results are as follows: (i) by the sediment retention action, the deposition commonly occurred in the SFD gully, and the deposition patterns are obviously different from upper to lower gully, (ii) more surprisingly, unlike trees or other shrubs, the seabuckthorn has good horizontal extending capacity by its root system, (iii) soil moisture, SOM, soil nutrients, vegetation coverage and biodiversity in the vegetated gully with the SFD are all markedly increased. The results showed the SFD is both effective and novel biological measure for ecological restoration and soil improvement within the Pisha Sandstone area.

  7. High-performance flexible ultraviolet photoconductors based on solution-processed ultrathin ZnO/Au nanoparticle composite films

    PubMed Central

    Jin, Zhiwen; Gao, Liang; Zhou, Qing; Wang, Jizheng

    2014-01-01

    Transparent ultraviolet (UV) ZnO thin film photoconductors are expected to have great applications in environmental monitoring, large-area displays, and optical communications, and they have drawn enormous interests in recent years. However, at present their performances are not satisfactory: the responsivity R (a parameter characterizing the sensitivity of the device to light) is not high (<1.0 × 103 AW−1), and the transparency T is not high either (<80%). Realizing high R and high T remains a big challenge today. In this paper, by employing solution-processed ultrathin ZnO/Au nanoparticle composite films, R as high as 1.51 × 105 AW−1 and T of over 90% are achieved. High values for detectivity D* and linear dynamic range LDR are also obtained, which are 2.05 × 1015 Jones and 60 dB, respectively. Moreover, such high-performance devices can be fabricated on flexible PET (polyethylene terephthalate) substrates. PMID:24589625

  8. Flexible and High Performance Supercapacitors Based on NiCo2O4for Wide Temperature Range Applications.

    PubMed

    Gupta, Ram K; Candler, John; Palchoudhury, Soubantika; Ramasamy, Karthik; Gupta, Bipin Kumar

    2015-01-01

    Binder free nanostructured NiCo2O4 were grown using a facile hydrothermal technique. X-ray diffraction patterns confirmed the phase purity of NiCo2O4. The surface morphology and microstructure of the NiCo2O4 analyzed by scanning electron microscopy (SEM) showed flower-like morphology composed of needle-like structures. The potential application of binder free NiCo2O4 as an electrode for supercapacitor devices was investigated using electrochemical methods. The cyclic voltammograms of NiCo2O4 electrode using alkaline aqueous electrolytes showed the presence of redox peaks suggesting pseudocapacitance behavior. Quasi-solid state supercapacitor device fabricated by sandwiching two NiCo2O4 electrodes and separating them by ion transporting layer. The performance of the device was tested using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The device showed excellent flexibility and cyclic stability. The temperature dependent charge storage capacity was measured for their variable temperature applications. Specific capacitance of the device was enhanced by ~150% on raising the temperature from 20 to 60 °C. Hence, the results suggest that NiCo2O4 grown under these conditions could be a suitable material for high performance supercapacitor devices that can be operated at variable temperatures. PMID:26482921

  9. Assessment of an action against environmental noise: Acoustic durability of a pavement surface with crumb rubber.

    PubMed

    Vázquez, V F; Luong, J; Bueno, M; Terán, F; Paje, S E

    2016-01-15

    Environmental noise is a worldwide problem that has an adverse effect in the quality of life of urban population. Some work has shown that there is a correlation between environmental noise and health issues as sleep disturbance or annoyance. This study presents the time evolution of a test track fabricated with an asphalt mixture with 20% of crumb rubber by weight of bitumen, added by the wet process. A complete surface characterization has been performed by determining tire/pavement sound levels, road texture profiles, in-situ dynamic stiffness and sound absorption of compacted and extracted sample cores. Two measurement campaigns were performed: just after mixture laying and after 3 years in service. This study confirms that the use of crumb rubber as a modifier of bituminous binders (CRMB) can improve the pavement characteristics: gap-graded mixtures with crumb rubber can be used in the action plans as urban rehabilitation measure to fight noise pollution. However, this noise reduction seems to decrease with age at a rate of approximately 0.15 dB(A) per year. PMID:26519582

  10. Feasibility of using 100% Recycled Asphalt Pavement mixtures for road construction

    NASA Astrophysics Data System (ADS)

    Carlson, Russell Edgar, IV

    Recycled Asphalt Pavement (RAP) is the largest recycled good in the United States and 80 million tons are recycled yearly, saving taxpayers about $1.5 billion dollars. This paper explores the possibility of utilizing 100% RAP materials in asphalt pavement. Asphalt mixtures are produced at 135°C in a typical asphalt plant. However, at 135°C, not all binder from RAP materials may not become effective for coating aggregates. The main objective of the study is to determine the amount of effective binder available from RAP in the asphalt plant. The 100% RAP mixes have aged binder that can alter mix designs and interaction with virgin binder. In this study, to determine low temperature cracking resistance and fatigue performance, samples were prepared using a 100% RAP mix with no virgin binder and a 100% RAP mix with virgin asphalt binder to achieve the optimum binder content of the mix. Second, to determine the effectiveness of binder from RAP materials, compaction tests were performed by heating RAP materials at various temperatures. It was found that 100% RAP mixes cannot be feasible for field use if additional virgin binder is added to reach the optimum asphalt content. Based on limited test results, the low temperature grade was not within proper limits but the beam fatigue testing results were acceptable. Based on compaction test results, additional heating is needed to increase the effectiveness of asphalt binder from RAP materials.

  11. Nondestructive testing of pavements and pavement bases. 1964-June, 1981 (citations from the NTIS Data Base). Report for 1964-Jun 81

    SciTech Connect

    Not Available

    1981-07-01

    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. (This updated bibliography contains 167 citations, 16 of which are new entries to the previous edition.)

  12. Nondestructive testing of pavements and pavement bases. 1964-March 1980 (citations from the NTIS Data Base). Report for 1964-March 1980

    SciTech Connect

    Habercom, G.E. Jr.

    1980-04-01

    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. (This updated bibliography contains 151 abstracts, 17 of which are new entries to the previous edition.)

  13. Assessing the improved performance of freestanding, flexible graphene and carbon nanotube hybrid foams for lithium ion battery anodes

    NASA Astrophysics Data System (ADS)

    Cohn, Adam P.; Oakes, Landon; Carter, Rachel; Chatterjee, Shahana; Westover, Andrew S.; Share, Keith; Pint, Cary L.

    2014-04-01

    We demonstrate the fabrication of three-dimensional freestanding foams of hybrid graphene-single-walled carbon nanotube nanomanufactured materials with reversible capacities of 2640 mA h g-1 at 0.186 A g-1 and 236 mA h g-1 at 27.9 A g-1. The Li storage behavior of this material is compared against other nanostructures in similar flexible foam platforms including graphene, ultra-thin graphite, and single-walled carbon nanotubes (SWNTs), and we elucidate the improved hybrid material performance due to the decoupling of lithium storage reaction energetics dictated by the SWNTs from the total storage capacity of the hybrid material. This work demonstrates a route to develop mechanically robust all-carbon electrodes with the potential for reversible Li-ion storage capacity approaching silicon, power capability of the best supercapacitors, and based on a material simultaneously usable as a charge collector and anode.We demonstrate the fabrication of three-dimensional freestanding foams of hybrid graphene-single-walled carbon nanotube nanomanufactured materials with reversible capacities of 2640 mA h g-1 at 0.186 A g-1 and 236 mA h g-1 at 27.9 A g-1. The Li storage behavior of this material is compared against other nanostructures in similar flexible foam platforms including graphene, ultra-thin graphite, and single-walled carbon nanotubes (SWNTs), and we elucidate the improved hybrid material performance due to the decoupling of lithium storage reaction energetics dictated by the SWNTs from the total storage capacity of the hybrid material. This work demonstrates a route to develop mechanically robust all-carbon electrodes with the potential for reversible Li-ion storage capacity approaching silicon, power capability of the best supercapacitors, and based on a material simultaneously usable as a charge collector and anode. Electronic supplementary information (ESI) available: ESI is available that includes (i) SEM and photographs of ultra-thin graphite foams, (ii) Raman spectra from SWNT and ultrathin graphite foams, (iii) CV measurements at higher scan rates, (iv) comparison of discharge characteristics of first, second, and 300th discharge, (v) Ragone plot showing power-energy characteristics of hybrid graphene-SWNT electrodes, and (vi) TEM images of multilayered graphene edges from graphene and graphene-SWNT hybrids, with interlayer spacing maps and FFT analysis. See DOI: 10.1039/c4nr00390j

  14. Some advances/results in monitoring road cracks from 2D pavement images within the scope of the collaborative FP7 TRIMM project

    NASA Astrophysics Data System (ADS)

    Baltazart, Vincent; Moliard, Jean-Marc; Amhaz, Rabih; Wright, Dean; Jethwa, Manish

    2015-04-01

    Monitoring road surface conditions is an important issue in many countries. Several projects have looked into this issue in recent years, including TRIMM 2011-2014. The objective of such projects has been to detect surface distresses, like cracking, raveling and water ponding, in order to plan effective road maintenance and to afford a better sustainability of the pavement. The monitoring of cracking conventionally focuses on open cracks on the surface of the pavement, as opposed to reflexive cracks embedded in the pavement materials. For monitoring surface condition, in situ human visual inspection has been gradually replaced by automatic image data collection at traffic speed. Off-line image processing techniques have been developed for monitoring surface condition in support of human visual control. Full automation of crack monitoring has been approached with caution, and depends on a proper manual assessment of the performance. This work firstly presents some aspects of the current state of monitoring that have been reported so far in the literature and in previous projects: imaging technology and image processing techniques. Then, the work presents the two image processing techniques that have been developed within the scope of the TRIMM project to automatically detect pavement cracking from images. The first technique is a heuristic approach (HA) based on the search for gradient within the image. It was originally developed to process pavement images from the French imaging device, Aigle-RN. The second technique, the Minimal Path Selection (MPS) method, has been developed within an ongoing PhD work at IFSTTAR. The proposed new technique provides a fine and accurate segmentation of the crack pattern along with the estimation of the crack width. HA has been assessed against the field data collection provided by Yotta and TRL with the imaging device Tempest 2. The performance assessment has been threefold: first it was performed against the reference data set including 130 km of pavement images over UK roads, second over a few selected short sections of contiguous pavement images, and finally over a few sample images as a case study. The performance of MPS has been assessed against an older image data base. Pixel-based PGT was available to provide the most sensitive performance assessment. MPS has shown its ability to provide a very accurate cracking pattern without reducing the image resolution on the segmented images. Thus, it allows measurement of the crack width; it is found to behave more robustly against the image texture and better matched for dealing with low contrast pavement images. The benchmarking of seven automatic segmentation techniques has been provided at both the pixel and the grid levels. The performance assessment includes three minimal path selection algorithms, namely MPS, Free Form Anisotropy (FFA), one geodesic contour with automatic selection of points of interests (GC-POI), HA, and two Markov-based methods. Among others, MPS approach reached the best performance at the pixel level while it is matched to the FFA approach at the grid level. Finally, the project has emphasized the need for a reliable ground truth data collection. Owing to its accuracy, MPS may serve as a reference benchmark for other methods to provide the automatic segmentation of pavement images at the pixel level and beyond. As a counterpart, MPS requires a reduction in the computing time. Keywords: cracking, automatic segmentation, image processing, pavement, surface distress, monitoring, DICE, performance

  15. Flexible and free-standing ternary Cd2GeO4 nanowire/graphene oxide/CNT nanocomposite film with improved lithium-ion battery performance.

    PubMed

    Wang, Linlin; Zhang, Xiaozhu; Shen, Guozhen; Peng, Xia; Zhang, Min; Xu, Jingli

    2016-03-01

    To realize flexible lithium-ion batteries (LIBs), the design of flexible electrode/current collector materials with high mechanical flexibility, superior conductivity and excellent electrochemical performance and electrical stability are highly desirable. In this work, we developed a new ternary Cd2GeO4 nanowire/graphene oxide/carbon nanotube nanocomposite (Cd2GeO4 NW/GO/CNT) film electrode. Benefiting from the efficient combination of GO and Cd2GeO4 NWs, our Cd2GeO4 NW/GO/CNT composite film exhibits a capacity of 784 mA h g(-1) after 30 cycles at 200 mA g(-1), which is 2.7 times higher than that of Cd2GeO4 NW/CNT film (290 mA h g(-1)). At a higher rate of 400 mA g(-1) and 1 A g(-1), the Cd2GeO4 NW/GO/CNT film delivers a stable capacity of 617 and 397 mA h g(-1), respectively. Even at 2.5 A g(-1), it still exhibits a high rate capacity of 180 mA h g(-1). The flexible Cd2GeO4 NW/GO/CNT film clearly demonstrates good cycling stability and rate performance for anode materials in LIBs. This route may be extended to design other flexible free-standing metal germanate nanocomposite anode materials. PMID:26822529

  16. Flexible and free-standing ternary Cd2GeO4 nanowire/graphene oxide/CNT nanocomposite film with improved lithium-ion battery performance

    NASA Astrophysics Data System (ADS)

    Wang, Linlin; Zhang, Xiaozhu; Shen, Guozhen; Peng, Xia; Zhang, Min; Xu, Jingli

    2016-03-01

    To realize flexible lithium-ion batteries (LIBs), the design of flexible electrode/current collector materials with high mechanical flexibility, superior conductivity and excellent electrochemical performance and electrical stability are highly desirable. In this work, we developed a new ternary Cd2GeO4 nanowire/graphene oxide/carbon nanotube nanocomposite (Cd2GeO4 NW/GO/CNT) film electrode. Benefiting from the efficient combination of GO and Cd2GeO4 NWs, our Cd2GeO4 NW/GO/CNT composite film exhibits a capacity of 784 mA h g-1 after 30 cycles at 200 mA g-1, which is 2.7 times higher than that of Cd2GeO4 NW/CNT film (290 mA h g-1). At a higher rate of 400 mA g-1 and 1 A g-1, the Cd2GeO4 NW/GO/CNT film delivers a stable capacity of 617 and 397 mA h g-1, respectively. Even at 2.5 A g-1, it still exhibits a high rate capacity of 180 mA h g-1. The flexible Cd2GeO4 NW/GO/CNT film clearly demonstrates good cycling stability and rate performance for anode materials in LIBs. This route may be extended to design other flexible free-standing metal germanate nanocomposite anode materials.

  17. Solid-state high performance flexible supercapacitors based on polypyrrole-MnO2-carbon fiber hybrid structure.

    PubMed

    Tao, Jiayou; Liu, Nishuang; Ma, Wenzhen; Ding, Longwei; Li, Luying; Su, Jun; Gao, Yihua

    2013-01-01

    A solid-state flexible supercapacitor (SC) based on organic-inorganic composite structure was fabricated through an "in situ growth for conductive wrapping" and an electrode material of polypyrrole (PPy)-MnO2 nanoflakes-carbon fiber (CF) hybrid structure was obtained. The conductive organic material of PPy greatly improved the electrochemical performance of the device. With a high specific capacitance of 69.3 F cm(-3) at a discharge current density of 0.1 A cm(-3) and an energy density of 6.16 × 10(-3) Wh cm(-3) at a power density of 0.04 W cm(-3), the device can drive a commercial liquid crystal display (LCD) after being charged. The organic-inorganic composite active materials have enormous potential in energy management and the "in situ growth for conductive wrapping" method might be generalized to open up new strategies for designing next-generation energy storage devices. PMID:23884478

  18. Solid-State High Performance Flexible Supercapacitors Based on Polypyrrole-MnO2-Carbon Fiber Hybrid Structure

    PubMed Central

    Tao, Jiayou; Liu, Nishuang; Ma, Wenzhen; Ding, Longwei; Li, Luying; Su, Jun; Gao, Yihua

    2013-01-01

    A solid-state flexible supercapacitor (SC) based on organic-inorganic composite structure was fabricated through an “in situ growth for conductive wrapping” and an electrode material of polypyrrole (PPy)-MnO2 nanoflakes-carbon fiber (CF) hybrid structure was obtained. The conductive organic material of PPy greatly improved the electrochemical performance of the device. With a high specific capacitance of 69.3 F cm−3 at a discharge current density of 0.1 A cm−3 and an energy density of 6.16 × 10−3 Wh cm−3 at a power density of 0.04 W cm−3, the device can drive a commercial liquid crystal display (LCD) after being charged. The organic-inorganic composite active materials have enormous potential in energy management and the “in situ growth for conductive wrapping” method might be generalized to open up new strategies for designing next-generation energy storage devices. PMID:23884478

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

    PubMed

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Qiao, Jiangang; Liu, Weizheng

    2014-08-01

    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.

  1. Recycled materials in asphalt pavements, January 1980-June 1991 (citations from the NTIS database). Rept. for Jan 80-Jun 91

    SciTech Connect

    Not Available

    1991-06-01

    The bibliography contains citations concerning the recycling of asphalt pavement materials, and the use of other recycled materials to manufacture asphalt pavement. Articles discuss methods used for recycling bituminous pavement including hot-mix and cold-mix. Materials used to improve recycled pavement, and recycled materials used in asphalt pavement include latexes, rubber scrap such as tires, glass shards, concretes, dusts, waste oils, roofing wastes, sulfur, and metal refining sludges. Testing and evaluation of recycled pavements both in laboratories and in test cases are considered. (The bibliography contains 75 citations.) (Also includes title list and subject index.)

  2. Three-dimensional skeleton networks of graphene wrapped polyaniline nanofibers: an excellent structure for high-performance flexible solid-state supercapacitors.

    PubMed

    Hu, Nantao; Zhang, Liling; Yang, Chao; Zhao, Jian; Yang, Zhi; Wei, Hao; Liao, Hanbin; Feng, Zhenxing; Fisher, Adrian; Zhang, Yafei; Xu, Zhichuan J

    2016-01-01

    Thin, robust, lightweight, and flexible supercapacitors (SCs) have aroused growing attentions nowadays due to the rapid development of flexible electronics. Graphene-polyaniline (PANI) hybrids are attractive candidates for high performance SCs. In order to utilize them in real devices, it is necessary to improve the capacitance and the structure stability of PANI. Here we report a hierarchical three-dimensional structure, in which all of PANI nanofibers (NFs) are tightly wrapped inside reduced graphene oxide (rGO) nanosheet skeletons, for high-performance flexible SCs. The as-fabricated film electrodes with this unique structure showed a highest gravimetric specific capacitance of 921 F/g and volumetric capacitance of 391 F/cm(3). The assembled solid-state SCs gave a high specific capacitance of 211 F/g (1 A/g), a high area capacitance of 0.9 F/cm(2), and a competitive volumetric capacitance of 25.6 F/cm(3). The SCs also exhibited outstanding rate capability (~75% retention at 20 A/g) as well as excellent cycling stability (100% retention at 10 A/g for 2000 cycles). Additionally, no structural failure and loss of performance were observed under the bending state. This structure design paves a new avenue for engineering rGO/PANI or other similar hybrids for high performance flexible energy storage devices. PMID:26795067

  3. Three-dimensional skeleton networks of graphene wrapped polyaniline nanofibers: an excellent structure for high-performance flexible solid-state supercapacitors

    NASA Astrophysics Data System (ADS)

    Hu, Nantao; Zhang, Liling; Yang, Chao; Zhao, Jian; Yang, Zhi; Wei, Hao; Liao, Hanbin; Feng, Zhenxing; Fisher, Adrian; Zhang, Yafei; Xu, Zhichuan J.

    2016-01-01

    Thin, robust, lightweight, and flexible supercapacitors (SCs) have aroused growing attentions nowadays due to the rapid development of flexible electronics. Graphene-polyaniline (PANI) hybrids are attractive candidates for high performance SCs. In order to utilize them in real devices, it is necessary to improve the capacitance and the structure stability of PANI. Here we report a hierarchical three-dimensional structure, in which all of PANI nanofibers (NFs) are tightly wrapped inside reduced graphene oxide (rGO) nanosheet skeletons, for high-performance flexible SCs. The as-fabricated film electrodes with this unique structure showed a highest gravimetric specific capacitance of 921 F/g and volumetric capacitance of 391 F/cm3. The assembled solid-state SCs gave a high specific capacitance of 211 F/g (1 A/g), a high area capacitance of 0.9 F/cm2, and a competitive volumetric capacitance of 25.6 F/cm3. The SCs also exhibited outstanding rate capability (~75% retention at 20 A/g) as well as excellent cycling stability (100% retention at 10 A/g for 2000 cycles). Additionally, no structural failure and loss of performance were observed under the bending state. This structure design paves a new avenue for engineering rGO/PANI or other similar hybrids for high performance flexible energy storage devices.

  4. Three-dimensional skeleton networks of graphene wrapped polyaniline nanofibers: an excellent structure for high-performance flexible solid-state supercapacitors

    PubMed Central

    Hu, Nantao; Zhang, Liling; Yang, Chao; Zhao, Jian; Yang, Zhi; Wei, Hao; Liao, Hanbin; Feng, Zhenxing; Fisher, Adrian; Zhang, Yafei; Xu, Zhichuan J.

    2016-01-01

    Thin, robust, lightweight, and flexible supercapacitors (SCs) have aroused growing attentions nowadays due to the rapid development of flexible electronics. Graphene-polyaniline (PANI) hybrids are attractive candidates for high performance SCs. In order to utilize them in real devices, it is necessary to improve the capacitance and the structure stability of PANI. Here we report a hierarchical three-dimensional structure, in which all of PANI nanofibers (NFs) are tightly wrapped inside reduced graphene oxide (rGO) nanosheet skeletons, for high-performance flexible SCs. The as-fabricated film electrodes with this unique structure showed a highest gravimetric specific capacitance of 921 F/g and volumetric capacitance of 391 F/cm3. The assembled solid-state SCs gave a high specific capacitance of 211 F/g (1 A/g), a high area capacitance of 0.9 F/cm2, and a competitive volumetric capacitance of 25.6 F/cm3. The SCs also exhibited outstanding rate capability (~75% retention at 20 A/g) as well as excellent cycling stability (100% retention at 10 A/g for 2000 cycles). Additionally, no structural failure and loss of performance were observed under the bending state. This structure design paves a new avenue for engineering rGO/PANI or other similar hybrids for high performance flexible energy storage devices. PMID:26795067

  5. Design Methodologies of Asphalt Pavement Used in China and Mozambique

    NASA Astrophysics Data System (ADS)

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

    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.

  6. High-performance large-scale flexible dye-sensitized solar cells based on anodic TiO2 nanotube arrays.

    PubMed

    Jen, Hsiu-Ping; Lin, Meng-Hung; Li, Lu-Lin; Wu, Hui-Ping; Huang, Wei-Kai; Cheng, Po-Jen; Diau, Eric Wei-Guang

    2013-10-23

    A simple strategy to fabricate flexible dye-sensitized solar cells involves the use of photoanodes based on TiO2 nanotube (TNT) arrays with rear illumination. The TNT films (tube length ∼35 μm) were produced via anodization, and sensitized with N719 dye for photovoltaic characterization. Pt counter electrodes of two types were used: a conventional FTO/glass substrate for a device of rigid type and an ITO/PEN substrate for a device of flexible type. These DSSC devices were fabricated into either a single-cell structure (active area 3.6×0.5 cm2) or a parallel module containing three single cells (total active area 5.4 cm2). The flexible devices exhibit remarkable performance with efficiencies η=5.40% (single cell) and 4.77% (parallel module) of power conversion, which outperformed their rigid counterparts with η=4.87% (single cell) and 4.50% (parallel model) under standard one-sun irradiation. The flexible device had a greater efficiency of conversion of incident photons to current and a broader spectral range than the rigid device; a thinner electrolyte layer for the flexible device than for the rigid device is a key factor to improve the light-harvesting ability for the TNT-DSSC device with rear illumination. Measurements of electrochemical impedance spectra show excellent catalytic activity and superior diffusion characteristics for the flexible device. This technique thus provides a new option to construct flexible photovoltaic devices with large-scale, light-weight, and cost-effective advantages for imminent applications in consumer electronics. PMID:24050628

  7. Should we be gritting pavements to prevent pedestrian injuries?

    PubMed

    Atenstaedt, Rob; Rees, Michael

    2013-05-01

    Unintentional injuries are an important public health issue, and are a significant burden on health and social services, especially during the winter months. Dr Rob Atenstaedt, Consultant in Public Health Medicine, Public Health Wales & Honorary Senior Lecturer, Bangor University and Professor Michael Rees, University Director of Medical Development & Professor of Cardiovascular Studies, Bangor University look at the importance of pavement gritting in preventing injuries and falls in pedestrians. PMID:23657235

  8. Kinect, a Novel Cutting Edge Tool in Pavement Data Collection

    NASA Astrophysics Data System (ADS)

    Mahmoudzadeh, A.; Firoozi Yeganeh, S.; Golroo, A.

    2015-12-01

    Pavement roughness and surface distress detection is of interest of decision makers due to vehicle safety, user satisfaction, and cost saving. Data collection, as a core of pavement management systems, is required for these detections. There are two major types of data collection: traditional/manual data collection and automated/semi-automated data collection. This paper study different non-destructive tools in detecting cracks and potholes. For this purpose, automated data collection tools, which have been utilized recently are discussed and their applications are criticized. The main issue is the significant amount of money as a capital investment needed to buy the vehicle. The main scope of this paper is to study the approach and related tools that not only are cost-effective but also precise and accurate. The new sensor called Kinect has all of these specifications. It can capture both RGB images and depth which are of significant use in measuring cracks and potholes. This sensor is able to take image of surfaces with adequate resolution to detect cracks along with measurement of distance between sensor and obstacles in front of it which results in depth of defects. This technology has been very recently studied by few researchers in different fields of studies such as project management, biomedical engineering, etc. Pavement management has not paid enough attention to use of Kinect in monitoring and detecting distresses. This paper is aimed at providing a thorough literature review on usage of Kinect in pavement management and finally proposing the best approach which is cost-effective and precise.

  9. The Effect of Immediate Post-Training Active and Passive Recovery Interventions on Anaerobic Performance and Lower Limb Flexibility in Professional Soccer Players

    PubMed Central

    Rey, Ezequiel; Lago-Peñas, Carlos; Casáis, Luis; Lago-Ballesteros, Joaquín

    2012-01-01

    The capacity to recover from intense training, competition and matches is considered an important determinant in soccer performance. At present, there is no consensus on the effect of post-training recovery interventions on subsequent training session. The aim of this study was to determine the effectiveness of active (12 min submaximal running and 8 min of static stretching) and passive recovery (20 min sitting on a bench) interventions performed immediately after a training session on anaerobic performances (CMJ, 20 m sprint and Balsom agility test) and lower limb flexibility 24 h after the training. During two experimental sessions, 31 professional soccer players participated in a randomized fully controlled trial design. The first session was designed to evaluate the player’s anaerobic performances and lower limb flexibility (pretest). After baseline measurements, participants performed a standardized soccer training during which heart rate and RPE were recorded to evaluate the training load. At the end of the training unit all players were randomly assigned to the active recovery group and the passive recovery group. A second experimental session was organized to obtain the posttest values. Players performed the same test, administered in the same order than in the first trial. No significant differences between groups were observed in heart rate and RPE. No significant effect due to recovery interventions was found on lower limb flexibility and anaerobic performances except CMJ that posttest value was significantly greater in the active recovery group than in the passive group (p < 0.05). PMID:23486836

  10. Flexible binder-free metal fibril mat-supported silicon anode for high-performance lithium-ion batteries.

    PubMed

    Song, Seonghyun; Kim, Sang Woo; Lee, Dong Jin; Lee, Young-Gi; Kim, Kwang Man; Kim, Chang-Hyeon; Park, Jung-Ki; Lee, Yong Min; Cho, Kuk Young

    2014-07-23

    We report the fabrication of a flexible and binder-free metal fibril mat-supported Si anode (Si@SFM) by a simple process. The fabricated Si@SFM anode showed a high discharge capacity, ∼3000 mAh g(-1) at a current rate of 300 mA g(-1), and exhibited stable capacity retention, 90% at a 1 C rate (2000 mA g(-1)) after 200 cycles. The rate capability of the electrode was still high even when both the charge and the discharge current rates were markedly increased at the same time (1234 mAh g(-1) for charge-discharge time of ∼12 min). Moreover, owing to its mechanical flexibility, the Si@SFM can be adopted as a key component of flexible lithium-ion batteries (LIBs). After cell packaging, the rechargeable flexible battery under bending stress showed only a little capacity fading (86% of initial capacity) at 1000 mA g(-1) over 150 cycles. These results suggest that the Si@SFM electrode is readily suitable for use in rechargeable flexible LIBs. PMID:25020188

  11. GPR in Nondestructive Quality Assurance of New Asphalt Pavements

    NASA Astrophysics Data System (ADS)

    Poikajärvi, J.; Peisa, K.; Narbro, A.

    2012-04-01

    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.

  12. A road pavement full-scale test track containing stabilized bottom ashes.

    PubMed

    Toraldo, E; Saponaro, S

    2015-01-01

    This paper reports the results of a road pavement full-scale test track built by using stabilized bottom ash (SBA) from an Italian municipal solid waste incinerator as the aggregate in granular foundation, cement-bound mixes and asphalt concretes. The investigation focused on both the performance and the environmental compatibility of such mixes, especially with regard to the effects of mixing, laying and compaction. From the road construction point of view, the performance related to the effects of mixing, laying and compaction on constructability was assessed, as well as the volumetric and the mechanical properties. Environmental aspects were investigated by leaching tests. The results suggested that SBA meets the environmental Italian law for the reuse of non-hazardous waste and could be used as road material with the procedures, plants and equipment currently used for road construction. PMID:25354811

  13. High-performance flexible perovskite solar cells exploiting Zn2SnO4 prepared in solution below 100 °C

    NASA Astrophysics Data System (ADS)

    Shin, Seong Sik; Yang, Woon Seok; Noh, Jun Hong; Suk, Jae Ho; Jeon, Nam Joong; Park, Jong Hoon; Kim, Ju Seong; Seong, Won Mo; Seok, Sang Il

    2015-06-01

    Fabricating inorganic-organic hybrid perovskite solar cells (PSCs) on plastic substrates broadens their scope for implementation in real systems by imparting portability, conformability and allowing high-throughput production, which is necessary for lowering costs. Here we report a new route to prepare highly dispersed Zn2SnO4 (ZSO) nanoparticles at low-temperature (<100 °C) for the development of high-performance flexible PSCs. The introduction of the ZSO film significantly improves transmittance of flexible polyethylene naphthalate/indium-doped tin oxide (PEN/ITO)-coated substrate from ~75 to ~90% over the entire range of wavelengths. The best performing flexible PSC, based on the ZSO and CH3NH3PbI3 layer, exhibits steady-state power conversion efficiency (PCE) of 14.85% under AM 1.5G 100 mW.cm-2 illumination. This renders ZSO a promising candidate as electron-conducting electrode for the highly efficient flexible PSC applications.

  14. High power density nitridated hematite (α-Fe2O3) nanorods as anode for high-performance flexible lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Balogun, Muhammad-Sadeeq; Wu, Zupeng; Luo, Yang; Qiu, Weitao; Fan, Xiaolei; Long, Bei; Huang, Miao; Liu, Peng; Tong, Yexiang

    2016-03-01

    Flexible lithium ion batteries shows great attention as up-and-coming power source for the development of flexible and wearable electronic devices. However, they lack suitable electrode materials that are capable of withstanding rapid charging/discharging to facilitate high power density lithium ion batteries. In this work, we fabricate three dimensional (3D) nitridated hematite nanorods on a carbon cloth as high-performance anode for flexible lithium ion batteries. Our strategy to modify the surface of Fe2O3 via nitridation is to improve the electrical conductivity of Fe2O3. XPS, Raman spectra and SEM images confirmed the incorporation of nitriated surface. The fabricated device based on the nitridated hematite nanorod anode exhibiting high flexibility and outstanding lithium storage performance with power and energy densities of 24328 W kg-1 and 163 Wh kg-1, respectively at high current density of 10 A g-1. The high power density is due to the nitridation that provide a short lithium ion diffusion length and a high electronic conductivity in the nitridated-hematite nanorods leading to favorable kinetics electrical conductivity and significantly improved its rate capability.

  15. High-performance flexible perovskite solar cells exploiting Zn2SnO4 prepared in solution below 100 °C.

    PubMed

    Shin, Seong Sik; Yang, Woon Seok; Noh, Jun Hong; Suk, Jae Ho; Jeon, Nam Joong; Park, Jong Hoon; Kim, Ju Seong; Seong, Won Mo; Seok, Sang Il

    2015-01-01

    Fabricating inorganic-organic hybrid perovskite solar cells (PSCs) on plastic substrates broadens their scope for implementation in real systems by imparting portability, conformability and allowing high-throughput production, which is necessary for lowering costs. Here we report a new route to prepare highly dispersed Zn2SnO4 (ZSO) nanoparticles at low-temperature (<100 °C) for the development of high-performance flexible PSCs. The introduction of the ZSO film significantly improves transmittance of flexible polyethylene naphthalate/indium-doped tin oxide (PEN/ITO)-coated substrate from ∼75 to ∼90% over the entire range of wavelengths. The best performing flexible PSC, based on the ZSO and CH3NH3PbI3 layer, exhibits steady-state power conversion efficiency (PCE) of 14.85% under AM 1.5G 100 mW·cm(-2) illumination. This renders ZSO a promising candidate as electron-conducting electrode for the highly efficient flexible PSC applications. PMID:26096202

  16. High-performance flexible perovskite solar cells exploiting Zn2SnO4 prepared in solution below 100 °C

    PubMed Central

    Shin, Seong Sik; Yang, Woon Seok; Noh, Jun Hong; Suk, Jae Ho; Jeon, Nam Joong; Park, Jong Hoon; Kim, Ju Seong; Seong, Won Mo; Seok, Sang Il

    2015-01-01

    Fabricating inorganic–organic hybrid perovskite solar cells (PSCs) on plastic substrates broadens their scope for implementation in real systems by imparting portability, conformability and allowing high-throughput production, which is necessary for lowering costs. Here we report a new route to prepare highly dispersed Zn2SnO4 (ZSO) nanoparticles at low-temperature (<100 °C) for the development of high-performance flexible PSCs. The introduction of the ZSO film significantly improves transmittance of flexible polyethylene naphthalate/indium-doped tin oxide (PEN/ITO)-coated substrate from ∼75 to ∼90% over the entire range of wavelengths. The best performing flexible PSC, based on the ZSO and CH3NH3PbI3 layer, exhibits steady-state power conversion efficiency (PCE) of 14.85% under AM 1.5G 100 mW·cm−2 illumination. This renders ZSO a promising candidate as electron-conducting electrode for the highly efficient flexible PSC applications. PMID:26096202

  17. Enhanced photovoltaic performance of fully flexible dye-sensitized solar cells based on the Nb2O5 coated hierarchical TiO2 nanowire-nanosheet arrays

    NASA Astrophysics Data System (ADS)

    Liu, Wenwu; Hong, Chengxun; Wang, Hui-gang; Zhang, Mei; Guo, Min

    2016-02-01

    Nb2O5 coated hierarchical TiO2 nanowire-sheet arrays photoanode was synthesized on flexible Ti-mesh substrate by using a hydrothermal approach. The effect of TiO2 morphology and Nb2O5 coating layer on the photovoltaic performance of the flexible dye sensitized solar cells (DSSCs) based on Ti-mesh supported nanostructures were systematically investigated. Compared to the TiO2 nanowire arrays (NWAs), hierarchical TiO2 nanowire arrays (HNWAs) with enlarged internal surface area and strong light scattering properties exhibited higher overall conversion efficiency. The introduction of thin Nb2O5 coating layers on the surface of the TiO2 HNWAs played a key role in improving the photovoltaic performance of the flexible DSSC. By separating the TiO2 and electrolyte (I-/I3-), the Nb2O5 energy barrier decreased the electron recombination rate and increased electron collection efficiency and injection efficiency, resulting in improved Jsc and Voc. Furthermore, the influence of Nb2O5 coating amounts on the power conversion efficiency were discussed in detail. The fully flexible DSSC based on Nb2O5 coated TiO2 HNWAs films with a thickness of 14 μm displayed a well photovoltaic property of 4.55% (Jsc = 10.50 mA cm-2, Voc = 0.75 V, FF = 0.58). The performance enhancement of the flexible DSSC is largely attributed to the reduced electron recombination, enlarged internal surface area and superior light scattering ability of the formed hierarchical nanostructures.

  18. Insights into mechanical compression and the enhancement in performance by Mg(OH)2 coating in flexible dye sensitized solar cells.

    PubMed

    Peiris, T A Nirmal; Wijayantha, K G Upul; García-Cañadas, Jorge

    2014-02-21

    The engineering of flexible dye sensitized solar cells (DSCs) by mechanical compression is one of the methods that allow low temperature processing of these devices. However, suppressing the high temperature sintering process also significantly reduces the performance of the cells. In our previous work [J. Phys. Chem. C, 2012, 116, 1211], we have attempted to improve flexible DSC performance by coating the porous TiO2 photoanode with an electrodeposited Mg(OH)2 layer. In that work, we have obtained one of the highest photovoltages reported to date in flexible DSCs (847 mV). In order to gain more insights into the reasons for both poorer performance of compressed cells and the origin of the voltage enhancement achieved by the Mg(OH)2 coating, here we present an in-depth study by means of electrochemical impedance spectroscopy, Mott-Schottky plots analysis and open-circuit voltage decays. The existence of a shunt resistance in the mechanically compressed cells is revealed, causing an additional drawback to the poor inter-particle necking. By introducing the Mg(OH)2 coating the recombination in the cell becomes significantly reduced, being the key reason which is responsible for the higher photovoltage. Additionally, the coating and the compression cause modifications in the surface states and in the nature of the interfaces with the electrolyte. This induces TiO2 conduction band displacements and shifts of the relative position of the modified states that influence the performance. PMID:24424329

  19. Flexible n-Type High-Performance Thermoelectric Thin Films of Poly(nickel-ethylenetetrathiolate) Prepared by an Electrochemical Method.

    PubMed

    Sun, Yuanhui; Qiu, Lin; Tang, Liangpo; Geng, Hua; Wang, Hanfu; Zhang, Fengjiao; Huang, Dazhen; Xu, Wei; Yue, Peng; Guan, Ying-Shi; Jiao, Fei; Sun, Yimeng; Tang, Dawei; Di, Chong-An; Yi, Yuanping; Zhu, Daoben

    2016-05-01

    Flexible thin films of poly(nickel-ethylenetetrathiolate) prepared by an electrochemical method display promising n-type thermoelectric properties with the highest ZT value up to 0.3 at room temperature. Coexistence of high electrical conductivity and high Seebeck coefficient in this coordination polymer is attributed to its degenerate narrow-bandgap semiconductor behavior. PMID:26928813

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

    EPA Science Inventory

    The EPAs 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...

  1. 23 CFR 973.208 - Indian lands pavement management system (PMS).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Indian lands pavement management system (PMS). 973.208... PROGRAM Bureau of Indian Affairs Management Systems § 973.208 Indian lands pavement management system (PMS..., 2001, is available for inspection as prescribed at 49 CFR part 7. It is also available from...

  2. Asphalt Pavement Aging and Temperature Dependent Properties Using Functionally Graded Viscoelastic Model

    ERIC Educational Resources Information Center

    Dave, Eshan V.

    2009-01-01

    Asphalt concrete pavements are inherently graded viscoelastic structures. Oxidative aging of asphalt binder and temperature cycling due to climatic conditions being the major cause of non-homogeneity. Current pavement analysis and simulation procedures dwell on the use of layered approach to account for these non-homogeneities. The conventional…

  3. Permeable Pavement Monitoring at the Edison Environmental Center Demonstration Site - Abstract

    EPA Science Inventory

    The EPAs Urban Watershed Management Branch (UWMB) is monitoring an instrumented, working, 110-space pervious pavement parking at EPAs Edison Environmental Center (EEC). Permeable pavement systems are classified as stormwater best management practices (BMPs) which reduce runo...

  4. Permeable Pavement Monitoring at the Edison Environmental Center Demonstration Site - Abstract

    EPA Science Inventory

    The EPA’s Urban Watershed Management Branch (UWMB) is monitoring an instrumented, working, 110-space pervious pavement parking at EPA’s Edison Environmental Center (EEC). Permeable pavement systems are classified as stormwater best management practices (BMPs) which reduce runo...

  5. 23 CFR 972.208 - Federal lands pavement management system (PMS).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... “Pavement Management Guide,” AASHTO, 2001, is available for inspection as prescribed at 49 CFR part 7. It is... HIGHWAYS FISH AND WILDLIFE SERVICE MANAGEMENT SYSTEMS Fish and Wildlife Service Management Systems § 972... 23 Highways 1 2010-04-01 2010-04-01 false Federal lands pavement management system (PMS)....

  6. 23 CFR 970.208 - Federal lands pavement management system (PMS).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HIGHWAYS NATIONAL PARK SERVICE MANAGEMENT SYSTEMS National Park Service Management Systems § 970.208 Federal lands pavement management system (PMS). In addition to the requirements provided in § 970.204, the... 23 Highways 1 2010-04-01 2010-04-01 false Federal lands pavement management system (PMS)....

  7. 23 CFR 970.208 - Federal lands pavement management system (PMS).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... HIGHWAYS NATIONAL PARK SERVICE MANAGEMENT SYSTEMS National Park Service Management Systems § 970.208 Federal lands pavement management system (PMS). In addition to the requirements provided in § 970.204, the... 23 Highways 1 2011-04-01 2011-04-01 false Federal lands pavement management system (PMS)....

  8. 23 CFR 972.208 - Federal lands pavement management system (PMS).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... “Pavement Management Guide,” AASHTO, 2001, is available for inspection as prescribed at 49 CFR part 7. It is... HIGHWAYS FISH AND WILDLIFE SERVICE MANAGEMENT SYSTEMS Fish and Wildlife Service Management Systems § 972... 23 Highways 1 2011-04-01 2011-04-01 false Federal lands pavement management system (PMS)....

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

    EPA Science Inventory

    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...

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

    EPA Science Inventory

    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...

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

    EPA Science Inventory

    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...

  12. Recycled materials in asphalt pavements. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1995-03-01

    The bibliography contains citations concerning the recycling of asphalt pavement materials for road construction. Citations discuss asphalt concrete mixtures and recycling, recycled materials testing and evaluation, and pavement bases. Engineering and environmental aspects of recycled materials are examined. (Contains a minimum of 78 citations and includes a subject term index and title list.)

  13. Early-life study of the FA409 full-depth asphalt-concrete pavement sections

    SciTech Connect

    Hill, H.J.

    1988-01-01

    The Illinois Department of Transportation (IDOT) is currently implementing a mechanistic thickness-design procedure for full-depth asphalt-concrete pavements. This thesis is an early design-life investigation of full-depth asphalt-concrete pavements, constructed on FA409 near Carlyle, Illinois in 1986. Included in the study are: sampling and testing of paving and subgrade materials; extensive non-destructive testing (NDT) using the Falling Weight Deflectometer (FWD); development of techniques for interpreting NDT data; determination of as-built structural characteristics of the various pavement sections; evaluation of subsurface drainage and lime-treated soil behavior; and examination of the validity of the ILLI-PAVE computer model. The simplicity of a full-depth asphalt-concrete pavement allows useful information regarding pavement structure to be determined from FWD surface-deflection data. The ILLI-PAVE model was used in conjunction with statistical methods to quantify, in the form of regression equations or algorithms, the relationship between pavement structure (Tac, Eac, and Eri) and pavement response to FWD loading. Testing of pavement and subgrade material samples as used to validate these algorithms.

  14. Asphalt Pavement Aging and Temperature Dependent Properties Using Functionally Graded Viscoelastic Model

    ERIC Educational Resources Information Center

    Dave, Eshan V.

    2009-01-01

    Asphalt concrete pavements are inherently graded viscoelastic structures. Oxidative aging of asphalt binder and temperature cycling due to climatic conditions being the major cause of non-homogeneity. Current pavement analysis and simulation procedures dwell on the use of layered approach to account for these non-homogeneities. The conventional

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

    EPA Science Inventory

    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...

  16. Contemporary biogenic formation of clay pavements by eucalypts: further support for the phytotarium concept

    PubMed Central

    Pate, John S.; Verboom, William H.

    2009-01-01

    Background and Aims Clayey (sodosolic) pavements were studied in lateral root catchments of eucalypts where mixed myrtaceous:proteaceous vegetation was colonizing a dune of quartzitic sand blown out from a playa lake during late Pleistocene times. The site at Chillinup in south-west Western Australia provided an opportunity to examine these signature pavements in an unequivocally recent setting, and to assess their effects on competing non-eucalypt vegetation. Methods Pavements were located, and their extents and depths assessed by probing with steel rods, followed by corings and pit excavations using an air spade. Listings of plant species, growth forms and root morphologies were assembled for different vegetation zones in a representative transect across the dune. A deep cutting through the dune provided details on pavement morphology and modifications to the sand deposit bioengineered by eucalypt and heath vegetation. Key Results Clay pavements comprised closely spaced, round-topped columns whose mean diameters and depths varied between eucalypt species. Incipient pavement formation was characterized by clumps of clay deposited around fine root material. Pavements appeared to have been synthesized in situ from locally accessed and imported constituents. Understoreys on superficial pavements of a tree eucalypt were considerably less dense and biodiverse than on the deeper pavements of two mallee species, whilst most profuse vegetation cover was encountered in heath on unmodified (non-pavemented) sand. Certain species were restricted to superficially located pavements, whilst other ‘generalist’ species occurred widely across the dune. Relict pavements formed by earlier generations of eucalypts were present in certain areas of the transect and in soil profiles of the cutting. Some relict pavements colonized by proteaceous shrubs were overprinted with ferricrete. Conclusions Clay pavements formed by eucalypts have pronounced effects on understorey vegetation and may have been instrumental in establishment of the complex mosaics of mallee-woodland and proteaceous heathland observed across semi-arid landscapes of south-west Western Australia. Findings are related to earlier observations on the range of plant-mediated changes in soil profiles discussed in the recently advanced ‘Phytotarium’ concept. PMID:19141601

  17. Numerical simulation on the thermal response of heat-conducting asphalt pavements

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Wu, Shaopeng; Chen, Mingyu; Zhang, Yuan

    2010-05-01

    Using asphalt pavements as a solar collector is a subject of current interest all over the world because the sun provides a cheap and abundant source of clean and renewable energy, which can be captured by black asphalt pavements. A heat-conducting device is designed to absorb energy from the sun. In order to validate what parameters are critical in the asphalt collector, a finite element model is developed to predict the thermal response of the heat-conducting device compared to the conventional asphalt mixture. Some factors that may affect the asphalt pavement collector are considered, including the coefficient of heat conductivity of the asphalt pavement, the distance between pipes with the medium, water, and the pipe's diameter. Ultimately, the finite element model can provide pavement engineers with an efficient computational tool that can be a guide to the conductive asphalt solar collector's experiment in the laboratory.

  18. Study on Preserving Public Security of Installing 22 kV Distribution Equipment on Pavements

    NASA Astrophysics Data System (ADS)

    Murata, Koichi; Oka, Keisuke; Uemura, Satoshi; Ariga, Yasuo

    To cope with restructuring of electricity market, application of 22kV distribution systems to areas with high load density, is promising. To expand them, it is important to install 22kV distribution equipment on pavements and lots without fences. On the other hand, the neutral grounding method is expected for the 22kV distribution equipment in terms of rationalization of insulation. In this case, one line-to-ground fault current will be large. Therefore, to make safety of people, it is essential to decrease the contact voltage. In this paper, we will perform the simulation of current distribution in the case of one line-to-ground fault and study the security of human from the viewpoint of both step voltage and contact voltage. We will also clarify that we can lower the contact voltage by grounding mutually insulated inner box and outer box separately. Then we will propose the improved grounding method.

  19. Flexible Education.

    ERIC Educational Resources Information Center

    Saba, Farhad, Ed.

    1999-01-01

    The third in a series defining the field of distance education and its related concepts, this article focuses on flexible education, a term closely associated with open education. Discussion includes flexibility, autonomy and learner control; individualizing instruction; and management of instruction and instructional management software. (AEF)

  20. Flexibility Program

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    These brief guidelines for a muscular flexibility program state that the purpose of such a program is to increase the range of motion in order to avoid injuries and eliminate awkwardness in physical activities. A flexibility program is described as an extension of the warm-up period and should be an ongoing, permanent effort to lengthen muscles. A…

  1. Influence of pavement macrotexture on PM10 emissions from paved roads: A controlled study

    NASA Astrophysics Data System (ADS)

    China, Swarup; James, David E.

    2012-12-01

    This paper investigates influence of pavement macrotexture on paved road PM10 emissions. This study was conducted on different paved roadway types (local, collector and minor arterial) in the Las Vegas Valley, Nevada. Pavement macrotexture was measured using the ASTM E 965 sand patch method and the Digital Surface Roughness Meter™ (DSRM™). A controlled constant soil loading with known PM10 fraction was applied to cleaned road surfaces. The Desert Research Institute's (DRI) Mini-PI-SWERL™ (Portable In-Situ Wind ERosion Lab) was used to estimate PM10 mass emissions and cumulative mass emitted from pavement surfaces. PM10 mass emissions using controlled applied soil loadings generally declined with increasing pavement macrotexture at all applied shear levels. The relationships were statistically significant, and indicate that pavement macrotexture may need to be included in future development of revised paved road PM10 emissions factors. A change in the slope of emitted PM10 mass and pavement macrotexture occurred between 0.8 and 0.9 mm mean texture depth (MTD). Anomalies in PM10 mass emissions were observed at MTDs exceeding 1.2 mm. Two-way frequency distributions of pavement surface features obtained from DSRM measurements were analyzed to explain the observed anomalies. Results showed that pavement surface feature size distributions may influence on PM10 emissions from paved roads at similar MTDs. PM10 mass emissions were found to linearly depend on adjusted mode size of the pavement surface aggregate. A sharp decrease in friction velocities, computed from wind erosion theory, at MTDs above 0.9 mm matched an observed sharp decrease in PM10 emissions rates at MTDs above 0.9 mm, indicating that classical wind erosion theory could be adapted for non-erodible pavement surfaces and linearly relate PM10 emissions rates to applied shear stress at an aerodynamic roughness height of 0.075 mm.

  2. Coaxial CoMoO4 nanowire arrays with chemically integrated conductive coating for high-performance flexible all-solid-state asymmetric supercapacitors

    NASA Astrophysics Data System (ADS)

    Chen, Yaping; Liu, Borui; Liu, Qi; Wang, Jun; Li, Zhanshuang; Jing, Xiaoyan; Liu, Lianhe

    2015-09-01

    Flexible all-solid-state supercapacitors have offered promising applications as novel energy storage devices based on their merits, such as small size, low cost, light weight and high wearability for high-performance portable electronics. However, one major challenge to make flexible all-solid-state supercapacitors depends on the improvement of electrode materials with higher electrical conductivity properties and longer cycling stability. In this article, we put forward a simple strategy to in situ synthesize 1D CoMoO4 nanowires (NWs), using highly conductive CC and an electrically conductive PPy wrapping layer on CoMoO4 NW arrays for high performance electrode materials. The results show that the CoMoO4/PPy hybrid NW electrode exhibits a high areal specific capacitance of ca. 1.34 F cm-2 at a current density of 2 mA cm-2, which is remarkably better than the corresponding values for a pure CoMoO4 NW electrode of 0.7 F cm-2. An excellent cycling performance of nanocomposites of up to 95.2% (ca. 1.12 F cm-2) is achieved after 2000 cycles compared to pristine CoMoO4 NWs. In addition, we fabricate flexible all-solid-state ASC which can be cycled reversibly in the voltage range of 0-1.7 V, and exhibits a maximum energy density of 104.7 W h kg-1 (3.522 mW h cm-3), demonstrating great potential for practical applications in flexible energy storage electronics.Flexible all-solid-state supercapacitors have offered promising applications as novel energy storage devices based on their merits, such as small size, low cost, light weight and high wearability for high-performance portable electronics. However, one major challenge to make flexible all-solid-state supercapacitors depends on the improvement of electrode materials with higher electrical conductivity properties and longer cycling stability. In this article, we put forward a simple strategy to in situ synthesize 1D CoMoO4 nanowires (NWs), using highly conductive CC and an electrically conductive PPy wrapping layer on CoMoO4 NW arrays for high performance electrode materials. The results show that the CoMoO4/PPy hybrid NW electrode exhibits a high areal specific capacitance of ca. 1.34 F cm-2 at a current density of 2 mA cm-2, which is remarkably better than the corresponding values for a pure CoMoO4 NW electrode of 0.7 F cm-2. An excellent cycling performance of nanocomposites of up to 95.2% (ca. 1.12 F cm-2) is achieved after 2000 cycles compared to pristine CoMoO4 NWs. In addition, we fabricate flexible all-solid-state ASC which can be cycled reversibly in the voltage range of 0-1.7 V, and exhibits a maximum energy density of 104.7 W h kg-1 (3.522 mW h cm-3), demonstrating great potential for practical applications in flexible energy storage electronics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02961a

  3. Evaluation of Variable Refrigerant Flow Systems Performance and the Enhanced Control Algorithm on Oak Ridge National Laboratory s Flexible Research Platform

    SciTech Connect

    Im, Piljae; Munk, Jeffrey D; Gehl, Anthony C

    2015-06-01

    A research project “Evaluation of Variable Refrigerant Flow (VRF) Systems Performance and the Enhanced Control Algorithm on Oak Ridge National Laboratory’s (ORNL’s) Flexible Research Platform” was performed to (1) install and validate the performance of Samsung VRF systems compared with the baseline rooftop unit (RTU) variable-air-volume (VAV) system and (2) evaluate the enhanced control algorithm for the VRF system on the two-story flexible research platform (FRP) in Oak Ridge, Tennessee. Based on the VRF system designed by Samsung and ORNL, the system was installed from February 18 through April 15, 2014. The final commissioning and system optimization were completed on June 2, 2014, and the initial test for system operation was started the following day, June 3, 2014. In addition, the enhanced control algorithm was implemented and updated on June 18. After a series of additional commissioning actions, the energy performance data from the RTU and the VRF system were monitored from July 7, 2014, through February 28, 2015. Data monitoring and analysis were performed for the cooling season and heating season separately, and the calibrated simulation model was developed and used to estimate the energy performance of the RTU and VRF systems. This final report includes discussion of the design and installation of the VRF system, the data monitoring and analysis plan, the cooling season and heating season data analysis, and the building energy modeling study

  4. Strain gage installation and survivability on geosynthetics used in flexible pavements

    NASA Astrophysics Data System (ADS)

    Brooks, Jeremy A.

    The use of foil type strain gages on geosynthetics is poorly documented. In addition, very few individuals are versed in proper installation techniques or calibration methods. Due to the limited number of knowledgeable technicians there is no information regarding the susceptibility of theses gages to errors in installation by inexperienced installers. Also lacking in the documentation related to the use of foil type strain gages on geosynthetics is the survivability of the gages in field conditions. This research documented procedures for installation, calibration, and survivability used by the project team to instruments a full scale field installation in Marked Tree, AR. This research also addressed sensitivity to installation errors on both geotextile and geogrid. To document the process of gage installation an experienced technician, Mr. Joe Ables, formerly of the UASCE Waterways Experiment Station, was consulted. His techniques were combined with those discovered in related literature and those developed by the research team to develop processes that were adaptable to multiple gage geometries and parent geosynthetics. These processes were described and documented in a step by step manner with accompanying photographs, which should allow virtually anyone with basic electronics knowledge to install these gages properly. Calibration of the various geosynthetic / strain gage combinations was completed using wide width tensile testing on multiple samples of each material. The tensile testing process was documented and analyzed using digital photography to analyze strain on the strain gage itself. Calibration factors for each geosynthtics used in the full scale field testing were developed. In addition, the process was thoroughly documented to allow future researchers to calibrate additional strain gage and geosynthetic combinations. The sensitivity of the strain gages to installation errors was analyzed using wide width tensile testing and digital photography to determine the variability of the data collected from gages with noticeable installation errors as compared to properly installed gages. Induced errors varied based on the parent geosynthetics material, but included excessive and minimal waterproofing, gage rotation, gage shift, excessive and minimal adhesive, and excessive and minimal adhesive impregnation loads. The results of this work indicated that minor errors in geotextile gage installation that are noticeable and preventable by the experienced installer have no statistical significance on the data recorded during the life span of geotextile gages; however the lifespan of the gage may be noticeably shortened by such errors. Geogrid gage installation errors were found to cause statistically significant changes in the data recorded from improper installations. The issue of gage survivability was analyzed using small scale test sections instrumented and loaded similarly to field conditions anticipated during traditional roadway construction. Five methods of protection were tested for both geotextile and geogrid including a sand blanket, inversion, semi-hemispherical PCV sections, neoprene mats, and geosynthetic wick drain. Based on this testing neoprene mats were selected to protect geotextile installed gages, and wick drains were selected to protect geogrid installed gages. These methods resulted in survivability rates of 73% and 100% in the full scale installation respectively. This research and documentation may be used to train technicians to install and calibrate geosynthetic mounted foil type strain gages. In addition, technicians should be able to install gages in the field with a high probability of gage survivability using the protection methods recommended.

  5. Integrated material and structural design method for flexible pavements. Volume 1: Technical reports

    NASA Astrophysics Data System (ADS)

    Baladi, G. Y.

    1988-12-01

    The research quantified relationships between structural and material mix design parameters and documented a laboratory test procedure for examining mix design from a structural viewpoint. Results of static and cyclic load triaxial, indirect tensile, and flexural beam tests are presented, compared, and discussed. The test specimens were made using three types of aggregate, two gradations, three viscosity graded asphalts, and three values of the percent air voids. For all specimens, the optimum asphalt content was determined using the standard Marshall mix design procedure. During the course of the investigation, a new indirect tensile test apparatus was designed, made, and used throughout the course of the investigation. The test data indicated that the indirect tensile test can be used to establish the asphalt mix design and to determine its structural properties, permanent deformation characteristics, and fatigue life.

  6. Amorphous Fe2O3 nanoshells coated on carbonized bacterial cellulose nanofibers as a flexible anode for high-performance lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Huang, Yang; Lin, Zixia; Zheng, Mingbo; Wang, Tianhe; Yang, Jiazhi; Yuan, Fanshu; Lu, Xiaoyu; Liu, Lin; Sun, Dongping

    2016-03-01

    A three-dimensional (3D) carbonaceous aerogel derived from biomass bacterial cellulose (BC) is introduced as a flexible framework for iron oxides in Li-ion batteries (LIBs). The 3D carbonized BC (CBC) with highly interconnected nanofibrous structure exhibits good electrical conductivity and mechanical stability. The amorphous Fe2O3 is tightly coated on the nanofibers of CBC through a simple in situ thermal decomposition method. The obtained amorphous Fe2O3 anode (denoted as A-Fe2O3@CBC) exhibits stable cycling performance and high rate capability when assembled into a half-cell, which is supposed to benefit from the well-dispersed Fe2O3 nanoshells and the hierarchical pores in A-Fe2O3@CBC composite. The rational design of the nanostructure could improve the transportation of electrons/ions and effectively alleviate volume changes of Fe2O3 during the electrochemical cycling. Meanwhile, the amorphous nature of the Fe2O3 in anode provides an enhanced capacitive-like lithium storage and flexible structure of the active materials, resulting in much higher specific capacity and longer cycle life when compared with its crystalline counterpart. This work provides a promising approach to design and construct the flexible metal oxide anode materials based on 3D carbonaceous aerogel for high-performance LIBs.

  7. High-Performance Flexible Perovskite Solar Cells by Using a Combination of Ultrasonic Spray-Coating and Low Thermal Budget Photonic Curing

    SciTech Connect

    Sanjib, Das; Yang, Bin; Gu, Gong; Joshi, Pooran C; Ivanov, Ilia N; Rouleau, Christopher; Aytug, Tolga; Geohegan, David B; Xiao, Kai

    2015-01-01

    Realizing the commercialization of high-performance and robust perovskite solar cells urgently requires the development of economically scalable processing techniques. Here we report a high-throughput ultrasonic spray-coating (USC) process capable of fabricating perovskite film-based solar cells on glass substrates with power conversion efficiency (PCE) as high as 13.04%. Perovskite films with high uniformity, crystallinity, and surface coverage are obtained in a single step. Moreover, we report USC processing on TiOx/ITO-coated polyethylene terephthalate (PET) substrates to realize flexible perovskite solar cells with PCE as high as 8.02% that are robust under mechanical stress. In this case, an optical curing technique was used to achieve a highly-conductive TiOx layer on flexible PET substrates for the first time. The high device performance and reliability obtained by this combination of USC processing with optical curing appears very promising for roll-to-roll manufacturing of high-efficiency, flexible perovskite solar cells.

  8. The effects of buffer layers on the performance and stability of flexible InGaZnO thin film transistors on polyimide substrates

    NASA Astrophysics Data System (ADS)

    Ok, Kyung-Chul; Ko Park, Sang-Hee; Hwang, Chi-Sun; Kim, H.; Soo Shin, Hyun; Bae, Jonguk; Park, Jin-Seong

    2014-02-01

    We demonstrated the fabrication of flexible amorphous indium gallium zinc oxide thin-film transistors (TFTs) on high-temperature polyimide (PI) substrates, which were debonded from the carrier glass after TFT fabrication. The application of appropriate buffer layers on the PI substrates affected the TFT performance and stability. The adoption of the SiNx/AlOx buffer layers as water and hydrogen diffusion barriers significantly improved the device performance and stability against the thermal annealing and negative bias stress, compared to single SiNx or SiOx buffer layers. The substrates could be bent down to a radius of curvature of 15 mm and the devices remained normally functional.

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

    NASA Astrophysics Data System (ADS)

    Wollny, Ines; Hartung, Felix; Kaliske, Michael

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Wollny, Ines; Hartung, Felix; Kaliske, Michael

    2016-02-01

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

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

    PubMed

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

    2012-03-01

    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 μm) 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

  12. Permeable pavement and stormwater management systems: a review.

    PubMed

    Imran, H M; Akib, Shatirah; Karim, Mohamed Rehan

    2013-01-01

    Uncontrolled stormwater runoff not only creates drainage problems and flash floods but also presents a considerable threat to water quality and the environment. These problems can, to a large extent, be reduced by a type of stormwater management approach employing permeable pavement systems (PPS) in urban, industrial and commercial areas, where frequent problems are caused by intense undrained stormwater. PPS could be an efficient solution for sustainable drainage systems, and control water security as well as renewable energy in certain cases. Considerable research has been conducted on the function of PPS and their improvement to ensure sustainable drainage systems and water quality. This paper presents a review of the use of permeable pavement for different purposes. The paper focuses on drainage systems and stormwater runoff quality from roads, driveways, rooftops and parking lots. PPS are very effective for stormwater management and water reuse. Moreover, geotextiles provide additional facilities to reduce the pollutants from infiltrate runoff into the ground, creating a suitable environment for the biodegradation process. Furthermore, recently, ground source heat pumps and PPS have been found to be an excellent combination for sustainable renewable energy. In addition, this study has identified several gaps in the present state of knowledge on PPS and indicates some research needs for future consideration. PMID:24527626

  13. Wavelet-based pavement image compression and noise reduction

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

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

  14. An Overview Of Pavement Management System For Industrial Areas

    NASA Astrophysics Data System (ADS)

    Hokam, Vivek S.

    2012-03-01

    ACT With the current surge in national economy the industrial traffic has increased many folds in terms of quantity of load and traffic volume. This results in early deterioration of the roads. Also the serviceability reduces hampering the industry's supply of raw material and transport of finished goods. An efficient road transportation system is of vitally important for smooth operations of industrial units. Construction of new roads needs an enormous investment. However, once constructed the road network system requires huge resources to maintain serviceability and to ensure safe passage at an appropriate speed and with low VOC (Vehicle Operating Cost). Road maintenance is therefore an essential function and should be carried out on a timely basis. The cost of providing and maintaining the roads for the industrial areas at an acceptable serviceability level is quite high. It is therefore essential for a transportation engineer to attempt establishing an acceptable pavement condition level from economic, safety and environmental point of view. In today's economic environment of constrained budgets, as the existing road infrastructure has aged, a more systematic approach towards determining maintenance and rehabilitation needs is necessary. The efficient pavement management system shall provide objective information and useful analysis to ensure consistent and cost effective decisions related to preservation of existing industrial road network in healthy condition.

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  17. Deconstructing a Plant Macromolecular Assembly: Chemical Architecture, Molecular Flexibility, And Mechanical Performance of Natural and Engineered Potato Suberins

    PubMed Central

    2015-01-01

    Periderms present in plant barks are essential protective barriers to water diffusion, mechanical breakdown, and pathogenic invasion. They consist of densely packed layers of dead cells with cell walls that are embedded with suberin. Understanding the interplay of molecular structure, dynamics, and biomechanics in these cell wall-associated insoluble amorphous polymeric assemblies presents substantial investigative challenges. We report solid-state NMR coordinated with FT-IR and tensile strength measurements for periderms from native and wound-healing potatoes and from potatoes with genetically modified suberins. The analyses include the intact suberin aromatic–aliphatic polymer and cell-wall polysaccharides, previously reported soluble depolymerized transmethylation products, and undegraded residues including suberan. Wound-healing suberized potato cell walls, which are 2 orders of magnitude more permeable to water than native periderms, display a strikingly enhanced hydrophilic–hydrophobic balance, a degradation-resistant aromatic domain, and flexibility suggestive of an altered supramolecular organization in the periderm. Suppression of ferulate ester formation in suberin and associated wax remodels the periderm with more flexible aliphatic chains and abundant aromatic constituents that can resist transesterification, attenuates cooperative hydroxyfatty acid motions, and produces a mechanically compromised and highly water-permeable periderm. PMID:24502663

  18. Hierarchical MnO2 nanowire/graphene hybrid fibers with excellent electrochemical performance for flexible solid-state supercapacitors

    NASA Astrophysics Data System (ADS)

    Ma, Wujun; Chen, Shaohua; Yang, Shengyuan; Chen, Wenping; Cheng, Yanhua; Guo, Yiwei; Peng, Shengjie; Ramakrishna, Seeram; Zhu, Meifang

    2016-02-01

    Towards rapid development of lightweight, flexible, and even wearable electronics, a highly efficient energy-storage device is required for their energy supply management. Graphene fiber-based supercapacitor is considered as one of the promising candidates because of the remarkable mechanical and electrical properties of graphene fibers. However, supercapacitors based on bare graphene fibers generally suffer a low capacitance, which certainly restricts their potentially wide applications. In this work, hierarchically structured MnO2 nanowire/graphene hybrid fibers are fabricated through a simple, scalable wet-spinning method. The hybrid fibers form mesoporous structure with large specific surface area of 139.9 m2 g-1. The mass loading of MnO2 can be as high as 40 wt%. Due to the synergistic effect between MnO2 nanowires and graphene, the main pseudocapacitance of MnO2 and the electric double-layer capacitance of graphene are improved simultaneously. In view of the practical demonstration, a highly flexible solid-state supercapacitor is fabricated by twisting of two MnO2/graphene fibers coated by polyvinyl alcohol/H3PO4 electrolyte. The supercapacitor exhibits a high volumetric capacitance (66.1 F cm-3, normalized by the total volume of two fiber electrodes), excellent cycling stability (96% capacitance retention over 10,000 cycles), high energy and power density (5.8 mWh cm-3 and 0.51 W cm-3, respectively).

  19. High performance flexible top-emitting warm-white organic light-emitting devices and chromaticity shift mechanism

    SciTech Connect

    Shi, Hongying; Deng, Lingling; Chen, Shufen E-mail: wei-huang@njupt.edu.cn; Xu, Ying; Zhao, Xiaofei; Cheng, Fan; Huang, Wei E-mail: wei-huang@njupt.edu.cn; Jiangsu-Singapore Joint Research Center for Organic/Bio- Electronics and Information Displays and Institute of Advanced Materials, Nanjing University of Technology, Nanjing 211816

    2014-04-15

    Flexible warm-white top-emitting organic light-emitting devices (TEOLEDs) are fabricated onto PET substrates with a simple semi-transparent cathode Sm/Ag and two-color phosphors respectively doped into a single host material TCTA. By adjusting the relative position of the orange-red EML sandwiched between the blue emitting layers, the optimized device exhibits the highest power/current efficiency of 8.07 lm/W and near 13 cd/A, with a correlated color temperature (CCT) of 4105 K and a color rendering index (CRI) of 70. In addition, a moderate chromaticity variation of (-0.025, +0.008) around warm white illumination coordinates (0.45, 0.44) is obtained over a large luminance range of 1000 to 10000 cd/m{sup 2}. The emission mechanism is discussed via delta-doping method and single-carrier device, which is summarized that the carrier trapping, the exciton quenching, the mobility change and the recombination zone alteration are negative to color stability while the energy transfer process and the blue/red/blue sandwiched structure are contributed to the color stability in our flexible white TEOLEDs.

  20. Facile chemical synthesis of nanoporous layered δ-MnO2 thin film for high-performance flexible electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Hu, Yu; Wang, Jun; Jiang, Xionghua; Zheng, Yanfeng; Chen, Zhenxing

    2013-04-01

    Layered δ-MnO2 thin films with a three-dimensional nanostructure are successfully fabricated on stainless steel foil substrates for flexible electrochemical capacitors by a facile and effective chemical bath deposition technology from ethanol and potassium permanganate solution at 15 °C. The as-prepared thin films display nanoporous morphology and a water contact angle of 20°. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses reveal that the thin films are composed of δ-MnO2. Electrochemical data demonstrate that the δ-MnO2 thin film electrodes can deliver a high special capacitance of 447 F/g at 2 mV/s, and provide a good capacitance retention ratio of 87% after 1000 continuous cycles at 10 mV/s in 0.5 M Na2SO4. Compressive and tensile bending tests show that the as-prepared electrodes can steadily work over a wide range of applied curvatures between -2.5 cm-1 (tension) and 2.5 cm-1 (compression). Only a small decrease in special capacitance (0.9% at a curvature of 2.5 cm-1 under compressive strain, or 1.2% at a curvature of -2.5 cm-1 under tensile strain) is observed even after bending for 200 cycles, indicating the excellent mechanical flexibility and electrochemical stability of the δ-MnO2 thin film electrodes.