Science.gov

Sample records for concrete overlays

  1. Bonded Concrete Overlays: Construction and Performance.

    DTIC Science & Technology

    1980-09-01

    report provides a review and summary of surface preparation of the existing slab, joint and crack treatment, bonding methods, concrete overlay mixtures...34Bonded, Thin-Lift Portland Cement Concrete Re- surfacing," Report on Project HRlgl, Clayton County and Iowa Highway Research Board, September 1977...34Resurfacing and Patching Concrete Pavement with Bonded Concrete ," Proceedings, Highway Research Board, Vol. 35, 1956. 8. Gillette, R. W.,"A 10-Year Report

  2. Overlays for plain jointed concrete pavements

    NASA Astrophysics Data System (ADS)

    Gulden, W.; Brown, D.

    1984-09-01

    This report describes the construction and performance of 4 concrete and 16 asphalt overlay test sections after nine years of traffic. The test sections were placed on I-85 which carries a substantial number of heavy trucks to determine what treatments and overlay type and thickness would give acceptable performance. The concrete overlay sections were placed in 1975 and consisted of 3 inch, 4 1/2 inch, and 6 inch CRC and 6 inch jointed PCC with 15 ft. and 30 ft. joint spacing. The asphalt sections were placed in 1976 with the variables being overlay thickness of 2 inches, 4 inches, and 6 inches and the placement of two geotextiles and strips of a waterproofing membrane for each overlay thickness. An Arkansas base test section was also included in the experiment.

  3. Tensile Bond Strength of Latex-Modified Bonded Concrete Overlays

    NASA Astrophysics Data System (ADS)

    Dubois, Cameron; Ramseyer, Chris

    2010-10-01

    The tensile bond strength of bonded concrete overlays was tested using the in-situ pull-off method described in ASTM C 1583 with the goal of determining whether adding latex to the mix design increases bond strength. One slab of ductile concrete (f'c > 12,000 psi) was cast with one half tined, i.e. roughened, and one half steel-troweled, i.e. smooth. The slab surface was sectioned off and overlay mixtures containing different latex contents cast in each section. Partial cores were drilled perpendicular to the surface through the overlay into the substrate. A tensile loading device applied a direct tensile load to each specimen and the load was increased until failure occurred. The tensile bond strength was then calculated for comparison between the specimens.

  4. Polymer concrete overlay on SH-51, bridge deck

    NASA Astrophysics Data System (ADS)

    Borg, T. M.

    1982-06-01

    A thin resinous overlay was placed on a sound bridge deck in Oklahoma to evaluate its performance over one year using various physical tests. The evaluation shows how well the overlay protects the reinforcing steel from corrosion due to deicing salts. The steps leading to the construction of the overlay are detailed as well as the actual placing of the overlay. The results of various physical tests are reported for both before and after the overlay.

  5. RESTORING A DAMAGED 16-YEAR -OLD INSULATING POLYMER CONCRETE DIKE OVERLAY: REPAIR MATERIALS AND TECHNOLOGIES.

    SciTech Connect

    SUGAMA,T.

    2007-01-01

    The objective of this program was to design and formulate organic polymer-based material systems suitable for repairing and restoring the overlay panels of insulating lightweight polymer concrete (ILPC) from the concrete floor and slope wall of a dike at KeySpan liquefied natural gas (LNG) facility in Greenpoint, Brooklyn, NY, just over sixteen years ago. It also included undertaking a small-scale field demonstration to ensure that the commercial repairing technologies were applicable to the designed and formulated materials.

  6. Plastic (wire-combed) grooving of a slip-formed concrete runway overlay at Patrick Henry Airport: An initial evaluation

    NASA Technical Reports Server (NTRS)

    Marlin, E. C.; Horne, W. B.

    1977-01-01

    A wire-comb technique is described for transversely grooving the surface of a freshly laid (plastic state) slip-formed concrete overlay installed at Patrick Henry Airport. This method of surface texturing yields better water drainage and pavement skid resistance than that obtained with an older conventional burlap drag concrete surface treatment installed on an adjacent portion of the runway.

  7. Strain distribution and crack detection in thin unbonded concrete pavement overlays with fully distributed fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Bao, Yi; Chen, Genda

    2016-01-01

    This study aims at evaluating the feasibility of strain measurement and crack detection in thin unbonded concrete pavement overlays with pulse prepump Brillouin optical time domain analysis. Single-mode optical fibers with two-layer and three-layer coatings, respectively, were applied as fully distributed sensors, their performances were compared with analytical predictions. They were successfully protected from damage during concrete casting of three full-scale concrete panels when 5 to 10-cm-thick protective mortar covers had been set for 2 h. Experimental results from three-point loading tests of the panels indicated that the strain distributions measured from the two types of sensors were in good agreement, and cracks can be detected at sharp peaks of the measured strain distributions. The two-layer and three-layer coated fibers can be used to measure strains up to 2.33% and 2.42% with a corresponding sensitivity of 5.43×10-5 and 4.66×10-5 GHz/μɛ, respectively. Two cracks as close as 7 to 9 cm can be clearly detected. The measured strains in optical fiber were lower than the analytical prediction by 10% to 25%. Their difference likely resulted from strain transfer through various coatings, idealized point loading, varying optical fiber embedment, and concrete heterogeneity.

  8. Overlay accuracy fundamentals

    NASA Astrophysics Data System (ADS)

    Kandel, Daniel; Levinski, Vladimir; Sapiens, Noam; Cohen, Guy; Amit, Eran; Klein, Dana; Vakshtein, Irina

    2012-03-01

    Currently, the performance of overlay metrology is evaluated mainly based on random error contributions such as precision and TIS variability. With the expected shrinkage of the overlay metrology budget to < 0.5nm, it becomes crucial to include also systematic error contributions which affect the accuracy of the metrology. Here we discuss fundamental aspects of overlay accuracy and a methodology to improve accuracy significantly. We identify overlay mark imperfections and their interaction with the metrology technology, as the main source of overlay inaccuracy. The most important type of mark imperfection is mark asymmetry. Overlay mark asymmetry leads to a geometrical ambiguity in the definition of overlay, which can be ~1nm or less. It is shown theoretically and in simulations that the metrology may enhance the effect of overlay mark asymmetry significantly and lead to metrology inaccuracy ~10nm, much larger than the geometrical ambiguity. The analysis is carried out for two different overlay metrology technologies: Imaging overlay and DBO (1st order diffraction based overlay). It is demonstrated that the sensitivity of DBO to overlay mark asymmetry is larger than the sensitivity of imaging overlay. Finally, we show that a recently developed measurement quality metric serves as a valuable tool for improving overlay metrology accuracy. Simulation results demonstrate that the accuracy of imaging overlay can be improved significantly by recipe setup optimized using the quality metric. We conclude that imaging overlay metrology, complemented by appropriate use of measurement quality metric, results in optimal overlay accuracy.

  9. Overlay caching scheme for overlay networks

    NASA Astrophysics Data System (ADS)

    Tran, Minh; Tavanapong, Wallapak

    2003-01-01

    Recent years have seen a tremendous growth of interests in streaming continuous media such as video over the Internet. This would create an enormous increase in the demand on various server and networking resources. To minimize service delays and to reduce loads placed on these resources, we propose an Overlay Caching Scheme (OCS) for overlay networks. OCS utilizes virtual cache structures to coordinate distributed overlay caching nodes along the delivery path between the server and the clients. OCS establishes and adapts these structures dynamically according to clients' locations and request patterns. Compared with existing video caching techniques, OCS offers better performances in terms of average service delays, server load, and network load in most cases in our study.

  10. Lithography overlay controller formulation

    NASA Astrophysics Data System (ADS)

    Bode, Christopher A.; Toprac, Anthony J.; Edwards, Richard D.; Edgar, Thomas F.

    2000-08-01

    Lithography overlay refers to the measurement of the alignment of successive patterns within the manufacture of semiconductor devices. Control of overlay has become of great importance in semiconductor manufacturing, as the tolerance for overlay error is continually shrinking in order to manufacture next-generation semiconductor products. Run-to-run control has become an attractive solution to many control problems within the industry, including overlay. The term run-to-run control refers to any automated procedure whereby recipe settings are updated between successive process runs in order to keep the process under control. The following discussion will present the formulation of such a controller by examining control of overlay. A brief introduction of overlay will be given, highlighting the control challenge overlay presents. A data management methodology that groups like processes together in order to improve controllability, referred to as control threads, will then be presented. Finally, a discussion of linear model predictive control will show its utility in feedback run-to-run control.

  11. Secure Overlay Services (SOS)

    DTIC Science & Technology

    2004-08-01

    of Service ISP : Internet Service Provider SOAP: Secure Overlay Access Point P2P : Peer-to-Peer ( network ) IP: Internet Protocol POP: Point of...approved, as shown in Figure 1. These routers are “deep” enough in the network (typically in an ISP’s Point of Presence), that the attack traffic does...capabilities, and novel approaches to routing in overlays and peer-to-peer ( P2P ) networks . To the extent possible, we strive to use existing systems and

  12. Pavement management and rehabilitation of portland cement concrete pavements

    NASA Astrophysics Data System (ADS)

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

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

  13. Promoting Learning of Instructional Design via Overlay Design Tools

    ERIC Educational Resources Information Center

    Carle, Andrew Jacob

    2012-01-01

    I begin by introducing Virtual Design Apprenticeship (VDA), a learning model--built on a solid foundation of education principles and theories--that promotes learning of design skills via overlay design tools. In VDA, when an individual needs to learn a new design skill or paradigm she is provided accessible, concrete examples that have been…

  14. Functional Overlay: An Illegitimate Diagnosis?

    PubMed Central

    Bromberg, Walter

    1979-01-01

    Functional overlay is not a recognized psychiatric diagnosis. Evaluating functional overlay and differentiating between this concept and organic conditions is important in medicolegal areas in which financial values are placed on pain and disability. Functional overlay is not malingering: the former is based on preconscious or unconscious mechanisms, the latter is consciously induced. In considering psychologic reactions to pain and disability, a gradient of simulation, malingering, symptom exaggeration, overvaluation, functional overlay and hysteria is useful. The dynamics of overlay are a combination of anxiety from body-image distortion and depression from decreased efficiency of the body, as well as the resulting psychosocial disruption in a patient's life. PMID:516698

  15. Overlay quality metric

    NASA Astrophysics Data System (ADS)

    Cohen, Guy; Amit, Eran; Klein, Dana; Kandel, Daniel; Levinski, Vladimir B.

    2012-03-01

    As overlay budget continues to shrink, an improved analysis of the different contributors to this budget is needed. A major contributor that has never been quantified is the accuracy of the measurements. KLA-Tencor developed a quality metric, that calculates and attaches an accuracy value to each OVL target. This operation is performed on the fly during measurement and can be applied without affecting MAM time or throughput. Using a linearity array we demonstrate that the quality metric identifies targets deviating from the intended OVL value, with no false alarms.

  16. Distributed Semantic Overlay Networks

    NASA Astrophysics Data System (ADS)

    Doulkeridis, Christos; Vlachou, Akrivi; Nørvåg, Kjetil; Vazirgiannis, Michalis

    Semantic Overlay Networks (SONs) have been recently proposed as a way to organize content in peer-to-peer (P2P) networks. The main objective is to discover peers with similar content and then form thematically focused peer groups. Efficient content retrieval can be performed by having queries selectively forwarded only to relevant groups of peers to the query. As a result, less peers need to be contacted, in order to answer a query. In this context, the challenge is to generate SONs in a decentralized and distributed manner, as the centralized assembly of global information is not feasible. Different approaches for exploiting the generated SONs for content retrieval have been proposed in the literature, which are examined in this chapter, with a particular focus on SON interconnections for efficient search. Several applications, such as P2P document and image retrieval, can be deployed over generated SONs, motivating the need for distributed and truly scalable SON creation. Therefore, recently several research papers focus on SONs as stated in our comprehensive overview of related work in the field of semantic overlay networks. A classification of existing algorithms according to a set of qualitative criteria is also provided. In spite of the rich existing work in the field of SONs, several challenges have not been efficiently addressed yet, therefore, future promising research directions are pointed out and discussed at the end of this chapter.

  17. Lightweight polymer concrete composites

    SciTech Connect

    Fontana, J.J.; Steinberg, M.; Reams, W.

    1985-08-01

    Lightweight polymer concrete composites have been developed with excellent insulating properties. The composites consist of lightweight aggregates such as expanded perlites, multicellular glass nodules, or hollow alumina silicate microspheres bound together with unsaturated polyester or epoxy resins. These composites, known as Insulating Polymer Concrete (IPC), have thermal conductivites from 0.09 to 0.19 Btu/h-ft-/sup 0/F. Compressive strengths, dependent upon the aggregates used, range from 1000 to 6000 psi. These materials can be precast or cast-in-place on concrete substrates. Recently, it has been demonstrated that these materials can also be sprayed onto concrete and other substrates. An overlay application of IPC is currently under way as dike insulation at an LNG storage tank facility. The composites have numerous potentials in the construction industry such as insulating building blocks or prefabricated insulating wall panels.

  18. How Concrete Is Concrete?

    ERIC Educational Resources Information Center

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  19. Culture systems: mineral oil overlay.

    PubMed

    Morbeck, Dean E; Leonard, Phoebe H

    2012-01-01

    Mineral oil overlay microdrop is commonly used during in vitro fertilization (IVF) procedures. Though mineral oil appears homogeneous, it is an undefined product that can vary in quality. Here, we describe the history, chemistry, processing, and optimal use of mineral oil for IVF and embryo culture.

  20. Assessment and prediction of drying shrinkage cracking in bonded mortar overlays

    SciTech Connect

    Beushausen, Hans Chilwesa, Masuzyo

    2013-11-15

    Restrained drying shrinkage cracking was investigated on composite beams consisting of substrate concrete and bonded mortar overlays, and compared to the performance of the same mortars when subjected to the ring test. Stress development and cracking in the composite specimens were analytically modeled and predicted based on the measurement of relevant time-dependent material properties such as drying shrinkage, elastic modulus, tensile relaxation and tensile strength. Overlay cracking in the composite beams could be very well predicted with the analytical model. The ring test provided a useful qualitative comparison of the cracking performance of the mortars. The duration of curing was found to only have a minor influence on crack development. This was ascribed to the fact that prolonged curing has a beneficial effect on tensile strength at the onset of stress development, but is in the same time not beneficial to the values of tensile relaxation and elastic modulus. -- Highlights: •Parameter study on material characteristics influencing overlay cracking. •Analytical model gives good quantitative indication of overlay cracking. •Ring test presents good qualitative indication of overlay cracking. •Curing duration has little effect on overlay cracking.

  1. Overlay metrology for double patterning processes

    NASA Astrophysics Data System (ADS)

    Leray, Philippe; Cheng, Shaunee; Laidler, David; Kandel, Daniel; Adel, Mike; Dinu, Berta; Polli, Marco; Vasconi, Mauro; Salski, Bartlomiej

    2009-03-01

    The double patterning (DPT) process is foreseen by the industry to be the main solution for the 32 nm technology node and even beyond. Meanwhile process compatibility has to be maintained and the performance of overlay metrology has to improve. To achieve this for Image Based Overlay (IBO), usually the optics of overlay tools are improved. It was also demonstrated that these requirements are achievable with a Diffraction Based Overlay (DBO) technique named SCOLTM [1]. In addition, we believe that overlay measurements with respect to a reference grid are required to achieve the required overlay control [2]. This induces at least a three-fold increase in the number of measurements (2 for double patterned layers to the reference grid and 1 between the double patterned layers). The requirements of process compatibility, enhanced performance and large number of measurements make the choice of overlay metrology for DPT very challenging. In this work we use different flavors of the standard overlay metrology technique (IBO) as well as the new technique (SCOL) to address these three requirements. The compatibility of the corresponding overlay targets with double patterning processes (Litho-Etch-Litho-Etch (LELE); Litho-Freeze-Litho-Etch (LFLE), Spacer defined) is tested. The process impact on different target types is discussed (CD bias LELE, Contrast for LFLE). We compare the standard imaging overlay metrology with non-standard imaging techniques dedicated to double patterning processes (multilayer imaging targets allowing one overlay target instead of three, very small imaging targets). In addition to standard designs already discussed [1], we investigate SCOL target designs specific to double patterning processes. The feedback to the scanner is determined using the different techniques. The final overlay results obtained are compared accordingly. We conclude with the pros and cons of each technique and suggest the optimal metrology strategy for overlay control in double

  2. Electro-osmotic techniques for removal of chloride from concrete and for emplacement of concrete sealants

    NASA Astrophysics Data System (ADS)

    Jayaprakash, G. P.; Bukovatz, J. E.; Ramamurti, K.; Gilliland, W. J.

    1982-08-01

    Chloride ion from bridge deck concrete can be removed by application of a direct current potential between bridge reinforcing steel (-) and a copper screen (+) conductor on the bridge surface. Soaring prices of all types of energy would make removal of all chloride prohibitatively expensive. The importance of verification of all electrical connections prior to the treatment is emphasized by the demonstration of concrete cracking when the steel was made a positive instead of a negative electrode. Data on effectiveness of calcium nitrite corrosion inhibitor added to the concrete overlay placed on electrotreated concrete is not extensive due to accidental damage to the test slabs.

  3. Analysis Of Overlay Distortion Patterns

    NASA Astrophysics Data System (ADS)

    Armitage, John D.; Kirk, Joseph P.

    1988-01-01

    A comprehensive geometrical approach is presented for the least-squares analysis of overlay distortion patterns into useful, physically meaningful systematic distortion subpatterns and an essentially non-systematic residue. A scheme of generally useful distortion sub-patterns is presented in graphic and algorithmic form; some of these sub-patterns are additions to those already in widespread use. A graphic and geometric approach is emphasized rather than an algebraic or statistical approach, and an example illustrates the value in utilizing the pattern-detecting ability of the eye-brain system. The conditions are described under which different distortion sub-patterns may interact, possibly leading to misleading or erroneous conclusions about the types and amounts of different distortions present. Examples of typical interaction situations are given, and recommendations are made for analytic procedures to avoid misinterpretation. It is noted that the lower-order distortion patterns preserve straight-line linearity, but that higher-order distortion may result in straight lines becoming curved. The principle of least-squares analysis is outlined and a simple polynomial data-fitting example is used to illustrate the method. Algorithms are presented for least-squares distortion analysis of overlay patterns, and an APL2 program is given to show how this may easily be implemented on a digital computer. The appendix extends the treatment to cases where small-angle approximation is not permissible.

  4. Environmental durability of polymer concrete

    SciTech Connect

    Palmese, G.R.; Chawalwala, A.J.

    1996-12-31

    Over the past two decades, polymer concrete has increasingly been used for a number of applications including piping, machine bases, chemically resistant flooring, and bridge overlays. Currently, the use of polymer concrete as a wear surface for polymeric composite bridge decks is being investigated. Polymer concrete is a particulate composite comprised of mineral aggregate bound by a polymeric matrix. Such materials possess significantly higher mechanical properties than Portland cement concrete. However, the mechanical characteristics and environmental durability of polymer concrete are influenced by a number of factors. Among these are the selection of aggregate and resin, surface treatment, and cure conditions. In this work the influence of matrix selection and cure history on the environmental durability of polymer concrete was investigated. Particular attention was given to the effects of water on composite properties and to the mechanisms by which degradation occurs. The basalt-based polymer concrete systems investigated were susceptible to attack by water. Furthermore, results suggest that property loss associated with water exposure was primarily a result of interfacial weakening.

  5. Disbond detection with piezoelectric wafer active sensors in RC structures strengthened with FRP composite overlays

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor; Harries, Kent; Petrou, Michael; Bost, Joel; Quattlebaum, Josh B.

    2003-12-01

    The capability of embedded piezoelectric wafer active sensors (PWAS) to perform in-situ nondestructive evaluation (NDE) for structural health monitoring (SHM) of reinforced concrete (RC) structures strengthened with fiber reinforced polymer (FRP) composite overlays is explored. First, the disbond detection method were developed on coupon specimens consisting of concrete blocks covered with an FRP composite layer. It was found that the presence of a disbond crack drastically changes the electromechanical (E/M) impedance spectrum measured at the PWAS terminals. The spectral changes depend on the distance between the PWAS and the crack tip. Second, large scale experiments were conducted on a RC beam strengthened with carbon fiber reinforced polymer (CFRP) composite overlay. The beam was subject to an accelerated fatigue load regime in a three-point bending configuration up to a total of 807,415 cycles. During these fatigue tests, the CFRP overlay experienced disbonding beginning at about 500,000 cycles. The PWAS were able to detect the disbonding before it could be reliably seen by visual inspection. Good correlation between the PWAS readings and the position and extent of disbond damage was observed. These preliminary results demonstrate the potential of PWAS technology for SHM of RC structures strengthened with FRP composite overlays.

  6. CFDP for Interplanetary Overlay Network

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.

    2011-01-01

    The CCSDS (Consultative Committee for Space Data Systems) File Delivery Protocol for Interplanetary Overlay Network (CFDP-ION) is an implementation of CFDP that uses IO' s DTN (delay tolerant networking) implementation as its UT (unit-data transfer) layer. Because the DTN protocols effect automatic, reliable transmission via multiple relays, CFDP-ION need only satisfy the requirements for Class 1 ("unacknowledged") CFDP. This keeps the implementation small, but without loss of capability. This innovation minimizes processing resources by using zero-copy objects for file data transmission. It runs without modification in VxWorks, Linux, Solaris, and OS/X. As such, this innovation can be used without modification in both flight and ground systems. Integration with DTN enables the CFDP implementation itself to be very simple; therefore, very small. Use of ION infrastructure minimizes consumption of storage and processing resources while maximizing safety.

  7. Use of concrete polymer materials in the transportation industry

    SciTech Connect

    Fontana, J J; Bartholomew, J

    1980-01-01

    Under contract to the FHWA, Brookhaven National Laboratory has developed a polymer concrete patching material that combines the premix characteristics of PCC with strength and durability properties that are higher than PCC. PC overlays have been shown to be highly impermeable to water and chlorides. Laydown techniques have been developed to allow bridge maintenance crews to place the overlays with little or no problems. Today several manufacturers are marketing PC materials, and their acceptance is becoming widespread.

  8. Root cause analysis of overlay metrology excursions with scatterometry overlay technology (SCOL)

    NASA Astrophysics Data System (ADS)

    Gutjahr, Karsten; Park, Dongsuk; Zhou, Yue; Cho, Winston; Ahn, Ki Cheol; Snow, Patrick; McGowan, Richard; Marciano, Tal; Ramanathan, Vidya; Herrera, Pedro; Itzkovich, Tal; Camp, Janay; Adel, Michael

    2016-03-01

    We demonstrate a novel method to establish a root cause for an overlay excursion using optical Scatterometry metrology. Scatterometry overlay metrology consists of four cells (two per directions) of grating on grating structures that are illuminated with a laser and diffracted orders measured in the pupil plane within a certain range of aperture. State of art algorithms permit, with symmetric considerations over the targets, to extract the overlay between the two gratings. We exploit the optical properties of the target to extract further information from the measured pupil images, particularly information that maybe related to any change in the process that may lead to an overlay excursion. Root Cause Analysis or RCA is being developed to identify different kinds of process variations (either within the wafer, or between different wafers) that may indicate overlay excursions. In this manuscript, we demonstrate a collaboration between Globalfoundries and KLA-Tencor to identify a symmetric process variation using scatterometry overlay metrology and RCA technique.

  9. Qmerit-calibrated overlay to improve overlay accuracy and device performance

    NASA Astrophysics Data System (ADS)

    Ullah, Md Zakir; Jazim, Mohamed Fazly Mohamed; Sim, Stella; Lim, Alan; Hiem, Biow; Chuen, Lieu Chia; Ang, Jesline; Lim, Ek Chow; Klein, Dana; Amit, Eran; Volkovitch, Roie; Tien, David; Choi, DongSub

    2015-03-01

    In advanced semiconductor industries, the overlay error budget is getting tighter due to shrinkage in technology. To fulfill the tighter overlay requirements, gaining every nanometer of improved overlay is very important in order to accelerate yield in high-volume manufacturing (HVM) fabs. To meet the stringent overlay requirements and to overcome other unforeseen situations, it is becoming critical to eliminate the smallest imperfections in the metrology targets used for overlay metrology. For standard cases, the overlay metrology recipe is selected based on total measurement uncertainty (TMU). However, under certain circumstances, inaccuracy due to target imperfections can become the dominant contributor to the metrology uncertainty and cannot be detected and quantified by the standard TMU. For optical-based overlay (OBO) metrology targets, mark asymmetry is a common issue which can cause measurement inaccuracy, and it is not captured by standard TMU. In this paper, a new calibration method, Archer Self-Calibration (ASC), has been established successfully in HVM fabs to improve overlay accuracy on image-based overlay (IBO) metrology targets. Additionally, a new color selection methodology has been developed for the overlay metrology recipe as part of this calibration method. In this study, Qmerit-calibrated data has been used for run-to-run control loop at multiple devices. This study shows that color filter can be chosen more precisely with the help of Qmerit data. Overlay stability improved by 10~20% with best color selection, without causing any negative impact to the products. Residual error, as well as overlay mean plus 3-sigma, showed an improvement of up to 20% when Qmerit-calibrated data was used. A 30% improvement was seen in certain electrical data associated with tested process layers.

  10. Diffraction based overlay and image based overlay on production flow for advanced technology node

    NASA Astrophysics Data System (ADS)

    Blancquaert, Yoann; Dezauzier, Christophe

    2013-04-01

    One of the main challenges for lithography step is the overlay control. For the advanced technology node like 28nm and 14nm, the overlay budget becomes very tight. Two overlay techniques compete in our advanced semiconductor manufacturing: the Diffraction based Overlay (DBO) with the YieldStar S200 (ASML) and the Image Based Overlay (IBO) with ARCHER (KLA). In this paper we will compare these two methods through 3 critical production layers: Poly Gate, Contact and first metal layer. We will show the overlay results of the 2 techniques, explore the accuracy and compare the total measurement uncertainty (TMU) for the standard overlay targets of both techniques. We will see also the response and impact for the Image Based Overlay and Diffraction Based Overlay techniques through a process change like an additional Hardmask TEOS layer on the front-end stack. The importance of the target design is approached; we will propose more adapted design for image based targets. Finally we will present embedded targets in the 14 FDSOI with first results.

  11. Correlation-aware multimedia content distribution in overlay networks

    NASA Astrophysics Data System (ADS)

    Zhu, Ying; Li, Baochun

    2006-01-01

    We address the question: What is the best way to construct a mesh overlay topology for multimedia content distribution, such that the highest streaming rate can be achieved? We model overlay capacity correlations as linear capacity constraints (LCC) and propose a distributed algorithm that constructs an overlay mesh which incorporates heuristically inferred linear capacity constraints. Our simulations results confirm the accuracy of representing overlays using our LCC model and show the LCC-overlay achieving substantial improvement in achievable flow rate.

  12. Scatterometry or imaging overlay: a comparative study

    NASA Astrophysics Data System (ADS)

    Hsu, Simon C. C.; Pai, Yuan Chi; Chen, Charlie; Yu, Chun Chi; Hsing, Henry; Wu, Hsing-Chien; Kuo, Kelly T. L.; Amir, Nuriel

    2015-03-01

    Most fabrication facilities today use imaging overlay measurement methods, as it has been the industry's reliable workhorse for decades. In the last few years, third-generation Scatterometry Overlay (SCOL™) or Diffraction Based Overlay (DBO-1) technology was developed, along another DBO technology (DBO-2). This development led to the question of where the DBO technology should be implemented for overlay measurements. Scatterometry has been adopted for high volume production in only few cases, always with imaging as a backup, but scatterometry overlay is considered by many as the technology of the future. In this paper we compare imaging overlay and DBO technologies by means of measurements and simulations. We outline issues and sensitivities for both technologies, providing guidelines for the best implementation of each. For several of the presented cases, data from two different DBO technologies are compared as well, the first with Pupil data access (DBO-1) and the other without pupil data access (DBO-2). Key indicators of overlay measurement quality include: layer coverage, accuracy, TMU, process robustness and robustness to process changes. Measurement data from real cases across the industry are compared and the conclusions are also backed by simulations. Accuracy is benchmarked with reference OVL, and self-consistency, showing good results for Imaging and DBO-1 technology. Process sensitivity and metrology robustness are mostly simulated with MTD (Metrology Target Designer) comparing the same process variations for both technologies. The experimental data presented in this study was done on ten advanced node layers and three production node layers, for all phases of the IC fabrication process (FEOL, MEOL and BEOL). The metrology tool used for most of the study is KLA-Tencor's Archer 500LCM system (scatterometry-based and imaging-based measurement technologies on the same tool) another type of tool is used for DBO-2 measurements. Finally, we conclude that

  13. Robotic weld overlay coatings for erosion control

    SciTech Connect

    Not Available

    1994-11-01

    The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB`s.

  14. Robotic weld overlay coatings for erosion control

    NASA Astrophysics Data System (ADS)

    The erosion of materials by the impact of solid particles has received increasing attention during the past twenty years. Recently, research has been initiated with the event of advanced coal conversion processes in which erosion plays an important role. The resulting damage, termed Solid Particle Erosion (SPE), is of concern primarily because of the significantly increased operating costs which result in material failures. Reduced power plant efficiency due to solid particle erosion of boiler tubes and waterfalls has led to various methods to combat SPE. One method is to apply coatings to the components subjected to erosive environments. Protective weld overlay coatings are particularly advantageous in terms of coating quality. The weld overlay coatings are essentially immune to spallation due to a strong metallurgical bond with the substrate material. By using powder mixtures, multiple alloys can be mixed in order to achieve the best performance in an erosive environment. However, a review of the literature revealed a lack of information on weld overlay coating performance in erosive environments which makes the selection of weld overlay alloys a difficult task. The objective of this project is to determine the effects of weld overlay coating composition and microstructure on erosion resistance. These results will lead to a better understanding of erosion mitigation in CFB's.

  15. Overlay improvement by zone alignment strategy

    NASA Astrophysics Data System (ADS)

    Huang, Chun-Yen; Lee, Ai-Yi; Shih, Chiang-Lin; Yang, Richer; Yuan, Michael; Chen, Henry; Chang, Ray

    2008-03-01

    It is evident that DRAM ground rule continues to shrink down to 90nm and beyond, overlay performance has become more and more critical and important. Wafer edge shows different behavior from center by processes, e.g. a tremendous misalignment at wafer edge makes yield loss . When a conventional linear model is used for alignment correction, higher uncorrectable overlay residuals mostly happen at wafer edge. Therefore, it's obviously necessary to introduce an innovational alignment correction methdology to reduce unwanted wafer edge effect. In this study, we demonstrate the achievement of moderating poor overlay in wafer edge area by a novel zone-dependent alignment strategy, the so-called "Zone Alignment (ZA)". The main difference between the conventional linear model and zone alignment strategy is that the latter compensates an improper averaging effect from first modeling through weighting all surrounding marks with a nonlinear model. In addition, the effects of mark quantity and sampling distribution from "Zone Alignment" are also introduced in this paper. The results of this study indicate that ZA can reduce uncorrectable overlay residual and improve wafer-to-wafer variation significantly. Furthermore, obvious yield improvement is verified by ZA strategy. In conclusion, Zone alignment is the noteworthy strategy for overlay improvement. Moreover, suitable alignment map and mark numbers should be taken into consideration carefully when ZA is applied for further technology node.

  16. Weld overlay coatings for erosion control

    SciTech Connect

    Levin, B.; DuPont, J.N.; Marder, A.R.

    1993-03-03

    A literature review was made. In spite of similarities between abrasive wear and solid particle erosion, weld overlay hardfacing alloys that exhibit high abrasion resistance may not necessarily have good erosion resistance. The performance of weld overlay hardfacing alloys in erosive environments has not been studied in detail. It is believed that primary-solidified hard phases such as carbides and intermetallic compounds have a strong influence on erosion resistance of weld overlay hardfacing alloys. However, relationships between size, shape, and volume fraction of hard phases in a hardfacing alloys and erosion resistance were not established. Almost all hardfacing alloys can be separated into two major groups based upon chemical compositions of the primary solidified hard phases: (a) carbide hardening alloys (Co-base/carbide, WC-Co and some Fe base superalloys); and (b) intermetallic hardening alloys (Ni-base alloys, austenitic steels, iron-aluminides).

  17. Robotic weld overlay coatings for erosion control

    SciTech Connect

    Levin, B.F.; Dupont, J.N.; Marder, A.R.

    1993-04-18

    Twelve weld overlay hardfacing alloys have been selected for preliminary erosion testing based on a literature review These alloys have been separated into three major groups: (1) Cobalt containing alloys, (2) Nickel-base alloys, (3) Iron base alloys. These alloys are being applied to carbon steel substrates and will undergo preliminary erosion testing to identify candidates weld overlay alloys for erosion control in CFB boilers. The candidate alloys selected from the preliminary erosion tests will then undergo more detailed evaluations in future research.

  18. KML Super Overlay to WMS Translator

    NASA Technical Reports Server (NTRS)

    Plesea, Lucian

    2007-01-01

    This translator is a server-based application that automatically generates KML super overlay configuration files required by Google Earth for map data access via the Open Geospatial Consortium WMS (Web Map Service) standard. The translator uses a set of URL parameters that mirror the WMS parameters as much as possible, and it also can generate a super overlay subdivision of any given area that is only loaded when needed, enabling very large areas of coverage at very high resolutions. It can make almost any dataset available as a WMS service visible and usable in any KML application, without the need to reformat the data.

  19. Colors, colored overlays, and reading skills.

    PubMed

    Uccula, Arcangelo; Enna, Mauro; Mulatti, Claudio

    2014-01-01

    In this article, we are concerned with the role of colors in reading written texts. It has been argued that colored overlays applied above written texts positively influence both reading fluency and reading speed. These effects would be particularly evident for those individuals affected by the so called Meares-Irlen syndrome, i.e., who experience eyestrain and/or visual distortions - e.g., color, shape, or movement illusions - while reading. This condition would interest the 12-14% of the general population and up to the 46% of the dyslexic population. Thus, colored overlays have been largely employed as a remedy for some aspects of the difficulties in reading experienced by dyslexic individuals, as fluency and speed. Despite the wide use of colored overlays, how they exert their effects has not been made clear yet. Also, according to some researchers, the results supporting the efficacy of colored overlays as a tool for helping readers are at least controversial. Furthermore, the very nature of the Meares-Irlen syndrome has been questioned. Here we provide a concise, critical review of the literature.

  20. Optical Overlay Versus Electric Probe Measurement

    NASA Astrophysics Data System (ADS)

    Mortensen, Keith Y.; Blachowicz, Betty A.

    1989-07-01

    The predominant method used in the past for the measurement of overlay has been manual reading of the "optical vernier." This method can be reasonably precise and has been sufficient for most semiconductor products made up until a few short years ago. The ever-increasing number of masking levels below 1.5-micron Minimum Feature Size (MFS) requires large statistical bases of overlay measurements with quick turnaround. No longer are 4 to 10 sites per wafer sufficient to accurately judge overlay, nor can we afford to wait 20 minutes for an operator to manually read these verniers. For years, Perkin-Elmer has used a unique and proprietary electrical probe system custom-built by Perkin-Elmer prior to the introduction of the Micralign Model 500. Capable of gathering large amounts of data and performing statistical analysis, it became a standard for overlay evaluation within Perkin-Elmer. An alternative to electrical probe is automated optical measurement. One such system is the Perkin-Elmer OMSTM. This system has the advantage of being "non destructive" and can be used to measure actual product wafers in process. This paper will provide a performance comparison of both techniques, optical and electrical. Using a mask with both optical and electrical probe patterns, a series of wafers was exposed. The evaluation compares accuracy, precision, speed, and statistical capabilities.

  1. Colors, colored overlays, and reading skills

    PubMed Central

    Uccula, Arcangelo; Enna, Mauro; Mulatti, Claudio

    2014-01-01

    In this article, we are concerned with the role of colors in reading written texts. It has been argued that colored overlays applied above written texts positively influence both reading fluency and reading speed. These effects would be particularly evident for those individuals affected by the so called Meares-Irlen syndrome, i.e., who experience eyestrain and/or visual distortions – e.g., color, shape, or movement illusions – while reading. This condition would interest the 12–14% of the general population and up to the 46% of the dyslexic population. Thus, colored overlays have been largely employed as a remedy for some aspects of the difficulties in reading experienced by dyslexic individuals, as fluency and speed. Despite the wide use of colored overlays, how they exert their effects has not been made clear yet. Also, according to some researchers, the results supporting the efficacy of colored overlays as a tool for helping readers are at least controversial. Furthermore, the very nature of the Meares-Irlen syndrome has been questioned. Here we provide a concise, critical review of the literature. PMID:25120525

  2. Design of Overlays for Rigid Airport Pavements

    DTIC Science & Technology

    1988-04-01

    Renture, A., and Mindess , S. 1986. "The Effect of Concrete Strength on Crack Patterns," Cement and Concrete Research,_ Vol 16, Pergamon Press Ltd...34 Miscellaneous Paper S-74-30, US Army Engineer Waterways Experiment Station, Vicksburg, Miss. 22. Harr, M. E. 1977 . Mechanics of Particulate Media...of Civil -. Engineers, New York. 33. Hutchinson, R., and Vedros, P. 1977 . "Performance of Heavy-Load Port- land Cement Concrete (Rigid) Airfield

  3. Overlay Tolerances For VLSI Using Wafer Steppers

    NASA Astrophysics Data System (ADS)

    Levinson, Harry J.; Rice, Rory

    1988-01-01

    In order for VLSI circuits to function properly, the masking layers used in the fabrication of those devices must overlay each other to within the manufacturing tolerance incorporated in the circuit design. The capabilities of the alignment tools used in the masking process determine the overlay tolerances to which circuits can be designed. It is therefore of considerable importance that these capabilities be well characterized. Underestimation of the overlay accuracy results in unnecessarily large devices, resulting in poor utilization of wafer area and possible degradation of device performance. Overestimation will result in significant yield loss because of the failure to conform to the tolerances of the design rules. The proper methodology for determining the overlay capabilities of wafer steppers, the most commonly used alignment tool for the production of VLSI circuits, is the subject of this paper. Because cost-effective manufacturing process technology has been the driving force of VLSI, the impact on productivity is a primary consideration in all discussions. Manufacturers of alignment tools advertise the capabilities of their equipment. It is notable that no manufacturer currently characterizes his aligners in a manner consistent with the requirements of producing very large integrated circuits, as will be discussed. This has resulted in the situation in which the evaluation and comparison of the capabilities of alignment tools require the attention of a lithography specialist. Unfortunately, lithographic capabilities must be known by many other people, particularly the circuit designers and the managers responsible for the financial consequences of the high prices of modern alignment tools. All too frequently, the designer or manager is confronted with contradictory data, one set coming from his lithography specialist, and the other coming from a sales representative of an equipment manufacturer. Since the latter generally attempts to make his

  4. SEM based overlay measurement between resist and buried patterns

    NASA Astrophysics Data System (ADS)

    Inoue, Osamu; Okagawa, Yutaka; Hasumi, Kazuhisa; Shao, Chuanyu; Leray, Philippe; Lorusso, Gian; Baudemprez, Bart

    2016-03-01

    With the continuous shrink in pattern size and increased density, overlay control has become one of the most critical issues in semiconductor manufacturing. Recently, SEM based overlay of AEI (After Etch Inspection) wafer has been used for reference and optimization of optical overlay (both Image Based Overlay (IBO) and Diffraction Based Overlay (DBO)). Overlay measurement at AEI stage contributes monitor and forecast the yield after formation by etch and calibrate optical measurement tools. however those overlay value seems difficult directly for feedback to a scanner. Therefore, there is a clear need to have SEM based overlay measurements of ADI (After Develop Inspection) wafers in order to serve as reference for optical overlay and make necessary corrections before wafers go to etch. Furthermore, to make the corrections as accurate as possible, actual device like feature dimensions need to be measured post ADI. This device size measurement is very unique feature of CDSEM , which can be measured with smaller area. This is currently possible only with the CD-SEM. This device size measurement is very unique feature of CD-SEM , which can be measured with smaller area. In this study, we assess SEM based overlay measurement of ADI and AEI wafer by using a sample from an N10 process flow. First, we demonstrate SEM based overlay performance at AEI by using dual damascene process for Via 0 (V0) and metal 1 (M1) layer. We also discuss the overlay measurements between litho-etch-litho stages of a triple patterned M1 layer and double pattern V0. Second, to illustrate the complexities in image acquisition and measurement we will measure overlay between M1B resist and buried M1A-Hard mask trench. Finally, we will show how high accelerating voltage can detect buried pattern information by BSE (Back Scattering Electron). In this paper we discuss the merits of this method versus standard optical metrology based corrections.

  5. Improvement of EUV mix-match overlay for production implementation

    NASA Astrophysics Data System (ADS)

    Park, Sarohan; Lee, ByoungHoon; Lee, Byong-Seog; Lee, Inwhan; Lim, Chang-Moon

    2016-03-01

    The improvement of overlay control in extreme ultra-violet (EUV) lithography is one of critical issues for successful mass production by using it. Especially it is important to improve the mix and match overlay or matched machine overlay (MMO) between EUV and ArF immersion tool, because EUV process will be applied to specific layers that have more competitive cost edge against ArF immersion multiple patterning with the early mass productivity of EUVL. Therefore it is necessary to consider the EUV overlay target with comparing the overlay specification of double patterning technology (DPT) and spacer patterning technology (SPT). This paper will discuss about required overlay controllability and current performance of EUV, and challenges for future improvement.

  6. Molecular Dynamics study of Pb overlayer on Cu(100)

    NASA Technical Reports Server (NTRS)

    Karimi, M.; Tibbits, P.; Ila, D.; Dalins, I.; Vidali, G.

    1991-01-01

    Isothermal-isobaric Molecular Dynamics (MD) simulation of a submonolayer Pb film in c(2x2) ordered structure adsorbed on a Cu(100) substrate showed retention of order to high T. The Embedded Atom Method (EAM) calculated the energy of atoms of overlayer and substrate. The time-averaged squared modulus of the two dimensional structure factor for the Pb overlayer measured the order of the overlayer. The results are for increasing T only, and require verification by simulated cooling.

  7. Investigation of Iron Aluminide Weld Overlays

    SciTech Connect

    Banovic, S.W.; DuPont, J.B.; Levin, B.F.; Marder, A.R.

    1999-08-02

    Conventional fossil fired boilers have been retrofitted with low NO(sub)x burners in order for the power plants to comply with new clean air regulations. Due to the operating characteristics of these burners, boiler tube sulfidation corrosion typically has been enhanced resulting in premature tube failure. To protect the existing panels from accelerated attack, weld overlay coatings are typically being applied. By depositing an alloy that offers better corrosion resistance than the underlying tube material, the wastage rates can be reduced. While Ni-based and stainless steel compositions are presently providing protection, they are expensive and susceptible to failure via corrosion-fatigue due to microsegregation upon solidification. Another material system presently under consideration for use as a coating in the oxidation/sulfidation environments is iron-aluminum. These alloys are relatively inexpensive, exhibit little microsegregation, and show excellent corrosion resistance. However, their use is limited due to weldability issues and their lack of corrosion characterization in simulated low NO(sub)x gas compositions. Therefore a program was initiated in 1996 to evaluate the use of iron-aluminum weld overlay coatings for erosion/corrosion protection of boiler tubes in fossil fired boilers with low NO(sub)x burners. Investigated properties included weldability, corrosion behavior, erosion resistance, and erosion-corrosion performance.

  8. Current Practices on Nighttime Pavement Construction Asphaltic Concrete.

    DTIC Science & Technology

    1982-07-01

    foot width. This production amounted to approximately 1520 tons per night. 9. Equipment: a. Asphalt Spreader. The Contractor utilized one Blaw Knox ...Diego, CA. to monitor the testing of the Port Authority requirements. 11. Grade Control Requirements. a. Ski. The Blaw Knox paving machine was specified...q 16. Crack Reflection Membrane: None. 17. Hot Mix Asphaltic Concrete Overlay Placing: a. Asphalt Spreaders Operating in Echelon. Only one Blaw - Knox

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

    NASA Astrophysics Data System (ADS)

    Scholer, C. F.

    1980-12-01

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

  10. A map overlay error model based on boundary geometry

    USGS Publications Warehouse

    Gaeuman, D.; Symanzik, J.; Schmidt, J.C.

    2005-01-01

    An error model for quantifying the magnitudes and variability of errors generated in the areas of polygons during spatial overlay of vector geographic information system layers is presented. Numerical simulation of polygon boundary displacements was used to propagate coordinate errors to spatial overlays. The model departs from most previous error models in that it incorporates spatial dependence of coordinate errors at the scale of the boundary segment. It can be readily adapted to match the scale of error-boundary interactions responsible for error generation on a given overlay. The area of error generated by overlay depends on the sinuosity of polygon boundaries, as well as the magnitude of the coordinate errors on the input layers. Asymmetry in boundary shape has relatively little effect on error generation. Overlay errors are affected by real differences in boundary positions on the input layers, as well as errors in the boundary positions. Real differences between input layers tend to compensate for much of the error generated by coordinate errors. Thus, the area of change measured on an overlay layer produced by the XOR overlay operation will be more accurate if the area of real change depicted on the overlay is large. The model presented here considers these interactions, making it especially useful for estimating errors studies of landscape change over time. ?? 2005 The Ohio State University.

  11. Improving text recognition by distinguishing scene and overlay text

    NASA Astrophysics Data System (ADS)

    Quehl, Bernhard; Yang, Haojin; Sack, Harald

    2015-02-01

    Video texts are closely related to the content of a video. They provide a valuable source for indexing and interpretation of video data. Text detection and recognition task in images or videos typically distinguished between overlay and scene text. Overlay text is artificially superimposed on the image at the time of editing and scene text is text captured by the recording system. Typically, OCR systems are specialized on one kind of text type. However, in video images both types of text can be found. In this paper, we propose a method to automatically distinguish between overlay and scene text to dynamically control and optimize post processing steps following text detection. Based on a feature combination a Support Vector Machine (SVM) is trained to classify scene and overlay text. We show how this distinction in overlay and scene text improves the word recognition rate. Accuracy of the proposed methods has been evaluated by using publicly available test data sets.

  12. Multicast and Bulk Lookup in Structured Overlay Networks

    NASA Astrophysics Data System (ADS)

    Ghodsi, Ali

    Structured overlay networks are often used to implement a Distributed Hash Table (DHT) abstraction. In this chapter, we argue that structured overlay networks are suitable for doing efficient group communication. We provide algorithms that enable a node to efficiently broadcast a message to all other nodes in a structured overlay network, without inducing any redundant messages. We also provide algorithms that enasble any node to efficiently send a message to all nodes in a specified set of identifiers. Such algorithms have found usage in many structured overlay networks that implement range queries. Similarly, we provide algorithms that enable any node to efficiently send a message to the nodes responsible for any of the identifiers in a specified set of identifiers. Finally, we look at a case study of implementing efficient Application Level Multicast (ALM) using the group communication algorithms on top of structured overlay networks.

  13. Weld overlay cladding with iron aluminides

    SciTech Connect

    Goodwin, G.M.

    1995-08-01

    The hot and cold cracking tendencies of some early iron aluminide alloy compositions have limited their use in applications where good weldability is required. Using hot crack testing techniques invented at ORNL, and experimental determinations of preheat and postweld heat treatment needed to avoid cold cracking, we have developed iron aluminide filler metal compositions which can be successfully used to weld overlay clad various substrate materials, including 9Cr-1Mo steel, 2-1/4Cr-1Mo steel, and 300-series austenitic stainless steels. Dilution must be carefully controlled to avoid crack-sensitive deposit compositions. The technique used to produce the current filler metal compositions is aspiration-casting, i.e. drawing the liquid from the melt into glass rods. Future development efforts will involve fabrication of composite wires of similar compositions to permit mechanized gas tungsten arc (GTA) and/or gas metal arc (GMA) welding.

  14. A constitutive model for an overlay coating

    NASA Technical Reports Server (NTRS)

    Nissley, D. M.; Swanson, G. A.

    1988-01-01

    Coatings are frequently applied to gas turbine blades and vanes to provide protection against oxidation and corrosion. The results of an experimental and analytical study to develop a constitutive model for an overlay coating is presented. Specimens were machined from a hot isostatically pressed billet of PWA 286. The tests consisted of isothermal stress relaxation cycles with monotonically increasing maximum strain and were conducted at various temperatures. The results were used to calculate the constants for various constitutive models, including the classical, the Walker isotropic, a simplified Walker, and Stowell models. A computerized regression analysis was used to calculate model constants from the data. The best fit was obtained for the Walker model, with the simplified Walker and classical models close behind.

  15. Envelopment technique and topographic overlays in bite mark analysis

    PubMed Central

    Djeapragassam, Parimala; Daniel, Mariappan Jonathan; Srinivasan, Subramanian Vasudevan; Ramadoss, Koliyan; Jimsha, Vannathan Kumaran

    2015-01-01

    Aims and Objectives: The aims and objectives of our study were to compare four sequential overlays generated using the envelopment technique and to evaluate inter- and intraoperator reliability of the overlays obtained by the envelopment technique. Materials and Methods: Dental stone models were prepared from impressions made from healthy individuals; photographs were taken and computer-assisted overlays were generated. The models were then enveloped in a different-color dental stone. After this, four sequential cuts were made at a thickness of 1mm each. Each sectional cut was photographed and overlays were generated. Thus, 125 overlays were generated and compared. Results: The scoring was done based on matching accuracy and the data were analyzed. The Kruskal-Wallis one-way analysis of variance (ANOVA) test was used to compare four sequential overlays and Spearman's rank correlation tests were used to evaluate the inter- and intraoperator reliability of the overlays obtained by the envelopment technique. Conclusion: Through our study, we conclude that the third and fourth cuts were the best among the four cuts and inter- and intraoperator reliability were found to be statistically significant at 5% level that is 95% confidence interval (P < 0.05). PMID:26816458

  16. Bayesian networks in overlay recipe optimization

    NASA Astrophysics Data System (ADS)

    Binns, Lewis A.; Reynolds, Greg; Rigden, Timothy C.; Watkins, Stephen; Soroka, Andrew

    2005-05-01

    Currently, overlay measurements are characterized by "recipe", which defines both physical parameters such as focus, illumination et cetera, and also the software parameters such as algorithm to be used and regions of interest. Setting up these recipes requires both engineering time and wafer availability on an overlay tool, so reducing these requirements will result in higher tool productivity. One of the significant challenges to automating this process is that the parameters are highly and complexly correlated. At the same time, a high level of traceability and transparency is required in the recipe creation process, so a technique that maintains its decisions in terms of well defined physical parameters is desirable. Running time should be short, given the system (automatic recipe creation) is being implemented to reduce overheads. Finally, a failure of the system to determine acceptable parameters should be obvious, so a certainty metric is also desirable. The complex, nonlinear interactions make solution by an expert system difficult at best, especially in the verification of the resulting decision network. The transparency requirements tend to preclude classical neural networks and similar techniques. Genetic algorithms and other "global minimization" techniques require too much computational power (given system footprint and cost requirements). A Bayesian network, however, provides a solution to these requirements. Such a network, with appropriate priors, can be used during recipe creation / optimization not just to select a good set of parameters, but also to guide the direction of search, by evaluating the network state while only incomplete information is available. As a Bayesian network maintains an estimate of the probability distribution of nodal values, a maximum-entropy approach can be utilized to obtain a working recipe in a minimum or near-minimum number of steps. In this paper we discuss the potential use of a Bayesian network in such a capacity

  17. Refractory concretes

    DOEpatents

    Holcombe, Jr., Cressie E.

    1979-01-01

    Novel concrete compositions comprise particles of aggregate material embedded in a cement matrix, said cement matrix produced by contacting an oxide selected from the group of Y.sub.2 O.sub.3, La.sub.2 O.sub.3, Nd.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Eu.sub.2 O.sub.3 and Gd.sub.2 O.sub.3 with an aqueous solution of a salt selected from the group of NH.sub.4 NO.sub.3, NH.sub.4 Cl, YCl.sub.3 and Mg(NO.sub.3).sub.2 to form a fluid mixture; and allowing the fluid mixture to harden.

  18. Lithography aware overlay metrology target design method

    NASA Astrophysics Data System (ADS)

    Lee, Myungjun; Smith, Mark D.; Lee, Joonseuk; Jung, Mirim; Lee, Honggoo; Kim, Youngsik; Han, Sangjun; Adel, Michael E.; Lee, Kangsan; Lee, Dohwa; Choi, Dongsub; Liu, Zephyr; Itzkovich, Tal; Levinski, Vladimir; Levy, Ady

    2016-03-01

    We present a metrology target design (MTD) framework based on co-optimizing lithography and metrology performance. The overlay metrology performance is strongly related to the target design and optimizing the target under different process variations in a high NA optical lithography tool and measurement conditions in a metrology tool becomes critical for sub-20nm nodes. The lithography performance can be quantified by device matching and printability metrics, while accuracy and precision metrics are used to quantify the metrology performance. Based on using these metrics, we demonstrate how the optimized target can improve target printability while maintaining the good metrology performance for rotated dipole illumination used for printing a sub-100nm diagonal feature in a memory active layer. The remaining challenges and the existing tradeoff between metrology and lithography performance are explored with the metrology target designer's perspective. The proposed target design framework is completely general and can be used to optimize targets for different lithography conditions. The results from our analysis are both physically sensible and in good agreement with experimental results.

  19. Weld overlay cladding with iron aluminides

    SciTech Connect

    Goodwin, G.M.

    1997-12-01

    The author has established a range of compositions for these alloys within which hot cracking resistance is very good, and within which cold cracking can be avoided in many instances by careful control of welding conditions, particularly preheat and postweld heat treatment. For example, crack-free butt welds have been produced for the first time in 12-mm thick wrought Fe{sub 3}Al plate. Cold cracking, however, still remains an issue in many cases. The author has developed a commercial source for composite weld filler metals spanning a wide range of achievable aluminum levels, and are pursuing the application of these filler metals in a variety of industrial environments. Welding techniques have been developed for both the gas tungsten arc and gas metal arc processes, and preliminary work has been done to utilize the wire arc process for coating of boiler tubes. Clad specimens have been prepared for environmental testing in-house, and a number of components have been modified and placed in service in operating kraft recovery boilers. In collaboration with a commercial producer of spiral weld overlay tubing, the author is attempting to utilize the new filler metals for this novel application.

  20. Mixing materials within zone boundaries using shape overlays

    SciTech Connect

    Grandy, J.

    1997-04-22

    Shape overlays provide a means of statically imposing a physical region containing specified material properties onto a zoned mesh. In the most general case, material interface boundaries are unrelated to mesh zone boundaries, causing zones to contain a mixture of materials, and the mesh itself is not uniform in physical space. We develop and apply an algorithm for shape overlays on nonorthogonal, nonuniform meshes in two dimensions. Examples of shape generation in a multiblock uid dynamics code are shown.

  1. Augmenting reality in Direct View Optical (DVO) overlay applications

    NASA Astrophysics Data System (ADS)

    Hogan, Tim; Edwards, Tim

    2014-06-01

    The integration of overlay displays into rifle scopes can transform precision Direct View Optical (DVO) sights into intelligent interactive fire-control systems. Overlay displays can provide ballistic solutions within the sight for dramatically improved targeting, can fuse sensor video to extend targeting into nighttime or dirty battlefield conditions, and can overlay complex situational awareness information over the real-world scene. High brightness overlay solutions for dismounted soldier applications have previously been hindered by excessive power consumption, weight and bulk making them unsuitable for man-portable, battery powered applications. This paper describes the advancements and capabilities of a high brightness, ultra-low power text and graphics overlay display module developed specifically for integration into DVO weapon sight applications. Central to the overlay display module was the development of a new general purpose low power graphics controller and dual-path display driver electronics. The graphics controller interface is a simple 2-wire RS-232 serial interface compatible with existing weapon systems such as the IBEAM ballistic computer and the RULR and STORM laser rangefinders (LRF). The module features include multiple graphics layers, user configurable fonts and icons, and parameterized vector rendering, making it suitable for general purpose DVO overlay applications. The module is configured for graphics-only operation for daytime use and overlays graphics with video for nighttime applications. The miniature footprint and ultra-low power consumption of the module enables a new generation of intelligent DVO systems and has been implemented for resolutions from VGA to SXGA, in monochrome and color, and in graphics applications with and without sensor video.

  2. ``Electric growth`` of metal overlayers on semiconductor substrates

    SciTech Connect

    Zhang, Z.; Cho, J.H. |; Niu, Q.; Shih, C.K.; Suo, Z.

    1998-02-01

    In this article, the authors present the main results from their recent studies of metal overlayer growth on semiconductor substrates. They show that a variety of novel phenomena can exist in such systems, resulting from several competing interactions. The confined motion of the conduction electrons within the metal overlayer can mediate a surprisingly long-range repulsive force between the metal-semiconductor interface and the growth front, acting to stabilize the overlayer. Electron transfer from the overlayer to the substrate leads to an attractive force between the two interfaces, acting to destabilize the overlayer. Interface-induced Friedel oscillations in electron density can further impose an oscillatory modulation onto the two previous interactions. These three competing factors, of all electronic nature, can make a flat metal overlayer critically, marginally, or magically stable, or totally unstable against roughening. The authors further show that, for many systems, these electronic effects can easily win over the effect of stress. First-principles studies of a few representative systems support the main features of the present electronic growth concept.

  3. Device-correlated metrology for overlay measurements

    NASA Astrophysics Data System (ADS)

    Chen, Charlie; Huang, George K. C.; Pai, Yuan Chi; Wu, Jimmy C. H.; Cheng, Yu Wei; Hsu, Simon C. C.; Yu, Chun Chi; Amir, Nuriel; Choi, Dongsub; Itzkovich, Tal; Tarshish-Shapir, Inna; Tien, David C.; Huang, Eros; Kuo, Kelly T. L.; Kato, Takeshi; Inoue, Osamu; Kawada, Hiroki; Okagawa, Yutaka; Huang, Luis; Hsu, Matthew; Su, Amei

    2014-10-01

    One of the main issues with accuracy is the bias between the overlay (OVL) target and actual device OVL. In this study, we introduce the concept of device-correlated metrology (DCM), which is a systematic approach to quantify and overcome the bias between target-based OVL results and device OVL values. In order to systematically quantify the bias components between target and device, we introduce a new hybrid target integrating an optical OVL target with a device mimicking critical dimension scanning electron microscope (CD-SEM) target. The hybrid OVL target is designed to accurately represent the process influence on the actual device. In the general case, the CD-SEM can measure the bias between the target and device on the same layer after etch inspection (AEI) for all layers, the OVL between layers at AEI for most cases and after develop inspection for limited cases such as double-patterning layers. The results have shown that for the innovative process compatible hybrid targets the bias between the target and device is small, within the order of CD-SEM noise. Direct OVL measurements by CD-SEM show excellent correlation between CD-SEM and optical OVL measurements at certain conditions. This correlation helps verify the accuracy of the optical measurement results and is applicable for the imaging base OVL method using several target types advance imaging metrology, advance imaging metrology in die OVL, and the scatterometrybase OVL method. Future plans include broadening the hybrid target design to better mimic each layer process conditions such as pattern density. Additionally, for memory devices we are developing hybrid targets which enable other methods of accuracy verification.

  4. Interplanetary Overlay Network Bundle Protocol Implementation

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.

    2011-01-01

    The Interplanetary Overlay Network (ION) system's BP package, an implementation of the Delay-Tolerant Networking (DTN) Bundle Protocol (BP) and supporting services, has been specifically designed to be suitable for use on deep-space robotic vehicles. Although the ION BP implementation is unique in its use of zero-copy objects for high performance, and in its use of resource-sensitive rate control, it is fully interoperable with other implementations of the BP specification (Internet RFC 5050). The ION BP implementation is built using the same software infrastructure that underlies the implementation of the CCSDS (Consultative Committee for Space Data Systems) File Delivery Protocol (CFDP) built into the flight software of Deep Impact. It is designed to minimize resource consumption, while maximizing operational robustness. For example, no dynamic allocation of system memory is required. Like all the other ION packages, ION's BP implementation is designed to port readily between Linux and Solaris (for easy development and for ground system operations) and VxWorks (for flight systems operations). The exact same source code is exercised in both environments. Initially included in the ION BP implementations are the following: libraries of functions used in constructing bundle forwarders and convergence-layer (CL) input and output adapters; a simple prototype bundle forwarder and associated CL adapters designed to run over an IPbased local area network; administrative tools for managing a simple DTN infrastructure built from these components; a background daemon process that silently destroys bundles whose time-to-live intervals have expired; a library of functions exposed to applications, enabling them to issue and receive data encapsulated in DTN bundles; and some simple applications that can be used for system checkout and benchmarking.

  5. Effect of Cement on Properties of Over-Burnt Brick Bituminous Concrete Mixes

    NASA Astrophysics Data System (ADS)

    Sarkar, Dipankar; Pal, Manish

    2016-06-01

    The present investigation is carried out to propose the use of cement coated over burnt brick aggregate in the preparation of bituminous concrete mix. The effect of cement on various mechanical properties such as Marshall stability, flow, Marshall quotient (stability to flow ratio), indirect tensile strength, stripping, rutting and fatigue life of bituminous concrete overlay has been evaluated. In this study, different cement percentages such as 2, 3, 4 and 5 % by weight of aggregate have been mixed with Over Burnt Brick Aggregate (OBBA). The laboratory results indicate that bituminous concrete prepared by 4 % cement coated OBBA gives the highest Marshall stability. The bituminous concrete mix with 4 % cement shows considerable improvement in various mechanical properties of the mix compared to the plain OBBA concrete mix.

  6. Overlay metrology solutions in a triple patterning scheme

    NASA Astrophysics Data System (ADS)

    Leray, Philippe; Mao, Ming; Baudemprez, Bart; Amir, Nuriel

    2015-03-01

    Overlay metrology tool suppliers are offering today several options to their customers: Different hardware (Image Based Overlay or Diffraction Based Overlay), different target designs (with or without segmentation) or different target sizes (from 5 um to 30 um). All these variations are proposed to resolve issues like robustness of the target towards process variations, be more representative of the design or increase the density of measurements. In the frame of the development of a triple patterning BEOL scheme of 10 nm node layer, we compare IBO targets (standard AIM, AIMid and multilayer AIMid). The metrology tools used for the study are KLA-Tencor's nextgeneration Archer 500 system (scatterometry- and imaging-based measurement technologies on the same tool). The overlay response and fingerprint of these targets will be compared using a very dense sampling (up to 51 pts per field). The benefit of indie measurements compared to the traditional scribes is discussed. The contribution of process effects to overlay values are compared to the contribution of the performance of the target. Different targets are combined in one measurement set to benefit from their different strengths (performance vs size). The results are summarized and possible strategies for a triple patterning schemes are proposed.

  7. Instructional geographic information science Map overlay and spatial abilities

    NASA Astrophysics Data System (ADS)

    Tricot, Thomas Alexander, II

    The fundamental goal of this study is to determine if the complex spatial concept of map overlay can be effectively learned by young adolescents through the utilization of an instructional technique based within the foundations of Instructional Geographic Information Science (InGIScience). Percent correct and reaction times were the measures used to analyze the ability of young adolescents to learn the intersect, erase, and union functions of map overlay. The ability to solve for missing inputs, output, or function was also analyzed. Young adolescents of the test group scored higher percent correct and recorded faster reaction times than those of the control group or adults of the expert group by the end of the experiment. The intersect function of map overlay was more difficult in terms of percent correct and reaction time than the erase or union functions. Solving for the first or second input consistently resulted in lower percent correct and higher reaction times throughout the experiment. No overall performance differences were shown to exist between males and females. Results of a subjective "real-world" test also indicated learning by young adolescents. This study has shown that the practice of repetitive instruction and testing has proven effective for enhancing spatial abilities with regard to the map overlay concept. This study found that with practice, young adolescents can learn the map overlay concept and perform at levels equal to or greater than adults. This study has helped to answer the question of whether this development of spatial abilities is possible.

  8. Constructing Overlay Networks with Short Paths and Low Communication Cost

    NASA Astrophysics Data System (ADS)

    Makikawa, Fuminori; Tsuchiya, Tatsuhiro; Kikuno, Tohru

    A Peer-To-Peer (P2P) application uses an overlay network which is a virtual network constructed over the physical network. Traditional overlay construction methods do not take physical location of nodes into consideration, resulting in a large amount of redundant traffic. Some proximity-aware construction methods have been proposed to address this problem. These methods typically connect nearby nodes in the physical network. However, as the number of nodes increases, the path length of a route between two distant nodes rapidly increases. To alleviate this problem, we propose a technique which can be incorporated in existing overlay construction methods. The idea behind this technique is to employ long links to directly connect distant nodes. Through simulation experiments, we show that using our proposed technique, networks can achieve small path length and low communication cost while maintaining high resiliency to failures.

  9. Using Mobile Agents and Overlay Networks to Secure Electrical Networks

    SciTech Connect

    Dawes, Neal A.; Prosser, Bryan J.; Fulp, Errin W.; McKinnon, Archibald D.

    2013-02-11

    ABSTRACT The use of wandering, mobile agents can provide a robust approach for managing, monitoring, and securing electrical distribution networks. However, the topological structure of electrical networks can affect system performance. For example, if the multi-agent system relies on a regular inspection rate (on average, points of interest are inspected with equal frequency), then locations that are not well connected will on average be inspected less frequently. This paper discusses creation and use of overlay networks that create a virtual grid graph can provide faster coverage and a more uniform average agent sampling rate. Using overlays agents wander a virtual neighborhood consisting of only points of interest that are interconnected in a regular fashion (each point has the same number of neighbors). Experimental results will show that an overlay can often provide better network coverage and a more uniform inspection rate, which can improve cyber security by providing a faster detection of threats.

  10. Using Mobile Agents and Overlay Networks to Secure Electrical Netoworks

    SciTech Connect

    Dawes, Neal A.; Prosser, Bryan J.; Fulp, Errin W.; McKinnon, Archibald D.

    2013-04-01

    ABSTRACT The use of wandering, mobile agents can provide a robust approach for managing, monitoring, and securing electrical distribution networks. However, the topological structure of electrical networks can affect system performance. For example, if the multi-agent system relies on a regular inspection rate (on average, points of interest are inspected with equal frequency), then locations that are not well connected will on average be inspected less frequently. This paper discusses creation and use of overlay networks that create a virtual grid graph can provide faster coverage and a more uniform average agent sampling rate. Using overlays agents wander a virtual neighborhood consisting of only points of interest that are interconnected in a regular fashion (each point has the same number of neighbors). Experimental results will show that an overlay can often provide better network coverage and a more uniform inspection rate, which can improve cyber security by providing a faster detection of threats

  11. Cooperative Resource Pricing in Service Overlay Networks for Mobile Agents

    NASA Astrophysics Data System (ADS)

    Nakano, Tadashi; Okaie, Yutaka

    The success of peer-to-peer overlay networks depends on cooperation among participating peers. In this paper, we investigate the degree of cooperation among individual peers required to induce globally favorable properties in an overlay network. Specifically, we consider a resource pricing problem in a market-oriented overlay network where participating peers sell own resources (e.g., CPU cycles) to earn energy which represents some money or rewards in the network. In the resource pricing model presented in this paper, each peer sets the price for own resource based on the degree of cooperation; non-cooperative peers attempt to maximize their own energy gains, while cooperative peers maximize the sum of own and neighbors' energy gains. Simulation results are presented to demonstrate that the network topology is an important factor influencing the minimum degree of cooperation required to increase the network-wide global energy gain.

  12. Lunar concrete for construction

    NASA Technical Reports Server (NTRS)

    Cullingford, Hatice S.; Keller, M. Dean

    1988-01-01

    Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base.

  13. Lunar concrete for construction

    NASA Technical Reports Server (NTRS)

    Cullingford, Hatice S.; Keller, M. Dean

    1992-01-01

    Feasibility of using concrete for lunar base construction was discussed recently without relevant data for the effects of vacuum on concrete. Our experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the Moon are provided in this paper, along with specific conclusions from the existing database.

  14. Lunar concrete for construction

    SciTech Connect

    Cullingford, H.S.; Keller, M.D.

    1988-01-01

    Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Our experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base. 10 refs., 3 figs., 2 tabs.

  15. Properties of Sulfur Concrete.

    DTIC Science & Technology

    1979-07-06

    This report summarizes the state of the art of sulfur concrete . Sulfur concrete is created by mixing molten sulfur with aggregate and allowing the...and many organic compounds. It works well as a rapid runway repair material. Sulfur concrete also has unfavorable properties. It has poor durability

  16. Implementing a Trust Overlay Framework for Digital Ecosystems

    NASA Astrophysics Data System (ADS)

    Malone, Paul; McGibney, Jimmy; Botvich, Dmitri; McLaughlin, Mark

    Digital Ecosystems, being decentralised in nature, are inherently untrustworthy environments. This is due to the fact that these environments lack a centralised gatekeeper and identity provider. In order for businesses to operate in these environments there is a need for security measures to support accountability and traceability. This paper describes a trust overlay network developed in the OPAALS project to allow entities participating in digital ecosystems to share experience through the exchange of trust values and to leverage on this network to determine reputation based trustworthiness of unknown and initially untrusted entities. An overlay network is described together with sample algorithms and a discussion on implementation.

  17. High-frequency nonreciprocal reflection from magnetic films with overlayers

    SciTech Connect

    Wang, Ying; Nie, Yan; Camley, R. E.

    2013-11-14

    We perform a theoretical study of the nonreciprocal reflection of high-frequency microwave radiation from ferromagnetic films with thin overlayers. Reflection from metallic ferromagnetic films is always near unity and shows no nonreciprocity. In contrast, reflection from a structure which has a dielectric overlayer on top of a film composed of insulated ferromagnetic nanoparticles or nanostructures can show significant nonreciprocity in the 75–80 GHz frequency range, a very high value. This can be important for devices such as isolators or circulators.

  18. Flexible TWDM PON with WDM overlay for converged services

    NASA Astrophysics Data System (ADS)

    Cheng, Ning

    2015-12-01

    This paper reviews recent developments of flexible TWDM PON (time- and wavelength-division multiplexed passive optical network) with pluggable transceivers for pay-as-you-grow deployment, load balancing, channel protection and power saving. Different architectures for TWDM PON with WDM (wavelength division multiplexed) overlay for converged broadband services are discussed and experimental results are presented for WDM overlay using low-cost self-seeded RSOA (reflective semiconductor optical amplifiers). Challenging issues and possible solutions for future evolution toward software defined flexible PONs (FlexPONs) are also discussed with respect to dynamic lambda flow, elastic bandwidth and flexible reach.

  19. Semantic overlay network for large-scale spatial information indexing

    NASA Astrophysics Data System (ADS)

    Zou, Zhiqiang; Wang, Yue; Cao, Kai; Qu, Tianshan; Wang, Zhongmin

    2013-08-01

    The increased demand for online services of spatial information poses new challenges to the combined filed of Computer Science and Geographic Information Science. Amongst others, these include fast indexing of spatial data in distributed networks. In this paper we propose a novel semantic overlay network for large-scale multi-dimensional spatial information indexing, called SON_LSII, which has a hybrid structure integrating a semantic quad-tree and Chord ring. The SON_LSII is a small world overlay network that achieves a very competitive trade-off between indexing efficiency and maintenance overhead. To create SON_LSII, we use an effective semantic clustering strategy that considers two aspects, i.e., the semantic of spatial information that peer holds in overlay network and physical network performances. Based on SON_LSII, a mapping method is used to reduce the multi-dimensional features into a single dimension and an efficient indexing algorithm is presented to support complex range queries of the spatial information with a massive number of concurrent users. The results from extensive experiments demonstrate that SON_LSII is superior to existing overlay networks in various respects, including scalability, maintenance, rate of indexing hits, indexing logical hops, and adaptability. Thus, the proposed SON_LSII can be used for large-scale spatial information indexing.

  20. Crosslayer Survivability in Overlay-IP-WDM Networks

    ERIC Educational Resources Information Center

    Pacharintanakul, Peera

    2010-01-01

    As the Internet moves towards a three-layer architecture consisting of overlay networks on top of the IP network layer on top of WDM-based physical networks, incorporating the interaction between and among network layers is crucial for efficient and effective implementation of survivability. This dissertation has four major foci as follows:…

  1. 12. DETAIL INDICATING TRANSITION FROM ORIGINAL SURFACE TO GUNITE OVERLAY ...

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

    12. DETAIL INDICATING TRANSITION FROM ORIGINAL SURFACE TO GUNITE OVERLAY ON UPSTREAM EMBANKMENT OF DAM (FROM REPAIRS COMPLETED IN 1977) - Upper Doughty Dam, 200 feet west of Garden State Parkway, 1.7 miles west of Absecon, Egg Harbor City, Atlantic County, NJ

  2. Efficient loss recovery in application overlay stored media streaming

    NASA Astrophysics Data System (ADS)

    Xie, Zhi-ping; Zheng, Geng-sheng; He, Gui-ming

    2005-07-01

    As the Internet does not widely support Internet protocol multicast, and content distribution networks are costly, application overlay has emerged as an alternative for deploying large scale streaming systems. Loss recovery in such architecture is a great challenge because of the correlation of packet losses results from the relaying nature, the variation of accumulated loss rates, and the dynamics of overlay structure, which is inevitable. Since each overlay node is capable of buffering a certain length of media data it has received, and there exists a temporal dependency between the buffers of nodes along a transmitting path, it is highly desirable to make full use of this buffering capability to carry out loss recovery. To this purpose, a retransmission-based approach is proposed in this paper. First, packet losses at a node are classified into two categories according to whether they can be repaired from the immediate upstream node, then, by making upstream nodes propagate loss information downstream, the proposed scheme enables each node efficiently recognize the nature of the loss it detects, and accordingly determine appropriate repair source, thus suppresses unnecessary retransmission requests. The proposed scheme is supported by theoretical analysis of the temporal dependency between overlay nodes, and its performance is verified by experimental results.

  3. Investigations of magnetic overlayers at the Advanced Photon Source

    SciTech Connect

    Tobin, J.G.; Yu, S.-W.; Butterfield, M.T.; Komesu, Takashi; Waddill, G.D.

    2010-08-27

    Magnetic overlayers of Fe and Co have been investigated with x-ray magnetic circular dichroism in x-ray absorption spectroscopy and photoelectron spectroscopy, including spin-resolved photoelectron spectroscopy, at Beamline 4 at the Advanced Photon Source. Particular emphasis was placed upon the interrogation of the 2p levels of the Fe.

  4. Investigations of Magnetic Overlayers at the Advanced Photon Source

    SciTech Connect

    Tobin, J G; Yu, S; Butterfield, M T

    2009-06-26

    Magnetic overlayers of Fe and Co have been investigated with X-ray Magnetic Circular Dichroism in X-ray Absorption Spectroscopy (XMCD-ABS) and Photoelectron Spectroscopy (PES), including Spin-Resolved Photoelectron Spectroscopy (SRPES), at Beamline 4 at the Advanced Photon Source (APS). Particular emphasis was placed upon the interrogation of the 2p levels of the Fe.

  5. Oriented Overlays for Clustering Client Requests to Data-Centric Network Services

    DTIC Science & Technology

    2006-01-01

    peer-to-peer ( P2P ) overlay network for data-sharing has been well studied by many researchers. Proposed approaches fall into two main cate- gories...structured [11]–[17], [21], [22] P2P overlay networks that we discussed in Section I, researchers have also examined construction of overlay

  6. Recycled and virgin plastics in fiber reinforced concrete. Final report, October 1994--August 1997

    SciTech Connect

    Tawfiq, K.S.

    1998-08-30

    The primary objectives of this study is to conduct a laboratory investigation to evaluate the intrinsic stress that can cause cracking of concrete mixed recommended by the Florida Department of Transportation with the addition of monofilament and fibrillated polypropylene and monofilament polyolefin fibers, subjected to highly cyclic loading. In addition, the flexural behavior of concrete reinforced with recycled post-consumer in-house made fibers will be study and Finite Element Methods (FEM) following laboratory work would be used to establish comparable numerical models for the flexural test and pavement overlays.

  7. In Situ Repair of Deteriorated Concrete in Hydraulic Structures: Feasibility Study

    DTIC Science & Technology

    1987-05-01

    19 • • 19 • 19 • • • • 20 Grinding • • • . • • • • • Jacketing • • • • • • . • • • • . . . . . . . . 20 . . . . . 20 Shotcreting ...Techniques Pressure Injection • • • • Polymer Impregnation • • • • • • • • • • Addition of Reinforcement •••.• Thin Reinforced Overlays and Shotcrete ...concrete elements that are ex- posed to corrosive materials or rapidly flowing water. 5. Shotcreting . This technique entails shooting concrete or mortar

  8. Reinforced Concrete Modeling

    DTIC Science & Technology

    1982-07-01

    AFWL-TR-82-9 AFWL-TR-82-9 REINFORCED CONCRETE MODELING H. L. Schreyer J. W. Jeter, Jr. New Mexico Engineering Reseprch Institute University of New...Subtitle) S. TYPE OF REPORT & PERIOD COVERED REINFORCED CONCRETE MODELING Final Report 6. PERFORMING OtG. REPORT NUMBER NMERI TA8-9 7. AUTHORg) S...loading were identified and used to evaluate current concrete models . Since the endochronic and viscoplastic models provide satisfactory descriptions

  9. 51. DETAIL VIEW OF VIVIANNA ERA CONCRETE HOUSE WITH CONCRETE ...

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

    51. DETAIL VIEW OF VIVIANNA ERA CONCRETE HOUSE WITH CONCRETE PATIO SLAB LOOKING SOUTHWEST. NOTICE MINE WORKINGS BACKGROUND LEFT. - Mariscal Quicksilver Mine & Reduction Works, Terlingua, Brewster County, TX

  10. Flutter Analysis of the Shuttle Tile Overlay Repair Concept

    NASA Technical Reports Server (NTRS)

    Bey, Kim S.; Scott, Robert C.; Bartels, Robert E.; Waters, William A.; Chen, Roger

    2007-01-01

    The Space Shuttle tile overlay repair concept, developed at the NASA Johnson Space Center, is designed for on-orbit installation over an area of damaged tile to permit safe re-entry. The thin flexible plate is placed over the damaged area and secured to tile at discreet points around its perimeter. A series of flutter analyses were performed to determine if the onset of flutter met the required safety margins. Normal vibration modes of the panel, obtained from a simplified structural analysis of the installed concept, were combined with a series of aerodynamic analyses of increasing levels of fidelity in terms of modeling the flow physics to determine the onset of flutter. Results from these analyses indicate that it is unlikely that the overlay installed at body point 1800 will flutter during re-entry.

  11. Stepper Overlay Calibration Using Alignment To A Latent Image

    NASA Astrophysics Data System (ADS)

    Edmark, Karl W.; Ausschnitt, Christopher P.

    1985-07-01

    We describe a method which minimizes the time required to set up and sustain optimum overlay performance of the DSW step-and-repeat system throughout a product wafer run. Improvement in both system performance and productivity is realized. Fundamental to the technique are the latent image formed by the exposure of photoresist, the AWA' global alignment system and the laser-metered stages of the DSW system. We eliminate the need to develop wafers and to read verniers during the DSW system set-up. Furthermore, we demonstrate the potential for on-the-fly calibration using product reticles and product wafers. The approach is generally applicable to the overlay calibration of optical exposure tools.

  12. CodedStream: live media streaming with overlay coded multicast

    NASA Astrophysics Data System (ADS)

    Guo, Jiang; Zhu, Ying; Li, Baochun

    2003-12-01

    Multicasting is a natural paradigm for streaming live multimedia to multiple end receivers. Since IP multicast is not widely deployed, many application-layer multicast protocols have been proposed. However, all of these schemes focus on the construction of multicast trees, where a relatively small number of links carry the multicast streaming load, while the capacity of most of the other links in the overlay network remain unused. In this paper, we propose CodedStream, a high-bandwidth live media distribution system based on end-system overlay multicast. In CodedStream, we construct a k-redundant multicast graph (a directed acyclic graph) as the multicast topology, on which network coding is applied to work around bottlenecks. Simulation results have shown that the combination of k-redundant multicast graph and network coding may indeed bring significant benefits with respect to improving the quality of live media at the end receivers.

  13. On-demand Overlay Networks for Large Scientific Data Transfers

    SciTech Connect

    Ramakrishnan, Lavanya; Guok, Chin; Jackson, Keith; Kissel, Ezra; Swany, D. Martin; Agarwal, Deborah

    2009-10-12

    Large scale scientific data transfers are central to scientific processes. Data from large experimental facilities have to be moved to local institutions for analysis or often data needs to be moved between local clusters and large supercomputing centers. In this paper, we propose and evaluate a network overlay architecture to enable highthroughput, on-demand, coordinated data transfers over wide-area networks. Our work leverages Phoebus and On-demand Secure Circuits and AdvanceReservation System (OSCARS) to provide high performance wide-area network connections. OSCARS enables dynamic provisioning of network paths with guaranteed bandwidth and Phoebus enables the coordination and effective utilization of the OSCARS network paths. Our evaluation shows that this approach leads to improved end-to-end data transfer throughput with minimal overheads. The achievedthroughput using our overlay was limited only by the ability of the end hosts to sink the data.

  14. HVM capabilities of CPE run-to-run overlay control

    NASA Astrophysics Data System (ADS)

    Subramany, Lokesh; Chung, Woong Jae; Gutjahr, Karsten; Garcia-Medina, Miguel; Sparka, Christian; Yap, Lipkong; Demirer, Onur; Karur-Shanmugam, Ramkumar; Riggs, Brent; Ramanathan, Vidya; Robinson, John C.; Pierson, Bill

    2015-03-01

    With the introduction of N2x and N1x process nodes, leading-edge factories are facing challenging demands of shrinking design margins. Previously un-corrected high-order signatures, and un-compensated temporal changes of high-order signatures, carry an important potential for improvement of on-product overlay (OPO). Until recently, static corrections per exposure (CPE), applied separately from the main APC correction, have been the industry's standard for critical layers [1], [2]. This static correction is setup once per device and layer and then updated periodically or when a machine change point generates a new overlay signature. This is a non-ideal setup for two reasons. First, any drift or sudden shift in tool signature between two CPE update periods can cause worse OPO and a higher rework rate, or, even worse, lead to yield loss at end of line. Second, these corrections are made from full map measurements that can be in excess of 1,000 measurements per wafer [3]. Advanced overlay control algorithms utilizing Run-to-Run (R2R) CPE can be used to reduce the overlay signatures on product in High Volume Manufacturing (HVM) environments. In this paper, we demonstrate the results of a R2R CPE control scheme in HVM. The authors show an improvement up to 20% OPO Mean+3Sigma values on several critical immersion layers at the 28nm and 14 nm technology nodes, and a reduction of out-of-spec residual points per wafer (validated on full map). These results are attained by closely tracking process tool signature changes by means of APC, and with an affordable metrology load which is significantly smaller than full wafer measurements.

  15. Both coloured overlays and coloured lenses can improve reading fluency, but their optimal chromaticities differ.

    PubMed

    Lightstone, A; Lightstone, T; Wilkins, A

    1999-07-01

    Some individuals read more fluently when the text is coloured: i.e., when coloured sheets of plastic (overlays) are placed upon the page, or when coloured lenses are worn. Overlays provide a surface colour whereas lenses mimic a change in the colour of a light source. The neural mechanisms that underlie colour constancy ensure that the chromaticity of overlays and lenses is processed differently by the visual system. We investigated (1) the relationship between the optimal colours of overlays and lenses, and (2) how reading rate is affected by a particular colour in overlays and lenses. In 100 patients we noted (1) the overlay(s) chosen from among the 29 combinations of the 10 IOO Intuitive Overlays which sample chromaticity systematically and (2) the chromaticity co-ordinates of the lenses subsequently chosen using the intuitive Colorimeter, a device providing a light source that can be adjusted in hue, saturation and luminance independently. The relationship between the chromaticities of the overlays and the lenses showed considerable variation. In a second study, patients attending the Specific Learning Difficulties clinic at the Institute of Optometry, London, were given overlays to use for two months. Seventeen who derived benefit were examined using the Intuitive Colorimeter. Patients were asked to read aloud randomly ordered common words (Wilkins Rate of Reading Test): (1) with no colour, (2) with the chosen overlay, (3) with lenses matching the chosen overlay and (4) with lenses matching the Colorimeter setting. The aids increased reading rate significantly only in conditions (2) and (4). There was no significant improvement when lenses matching the overlay colour were used, and under this condition the reading rate was significantly poorer than in conditions (2) and (4). The colour of a lens will improve reading only if it is selected under conditions that mimic a change in the colour of a light source: coloured overlays give no clinically reliable guide

  16. Diffusion Barriers to Increase the Oxidative Life of Overlay Coatings

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.; Lei, Jih-Fen

    1999-01-01

    Currently, most blades and vanes in the hottest section of aero gas turbine engines require some type of coating for oxidation protection. Newly developed single crystal superalloys have the mechanical potential to operate at increasingly higher component temperatures. However, at these elevated temperatures, coating/substrate interdiffusion can shorten the protective life of the coating. Diffusion barriers between overlay coatings and substrates are being examined to extend the protective life of the coating. A previously- developed finite-difference diffusion model has been modified to predict the oxidative life enhancement due to use of a diffusion barrier. The original diffusion model, designated COSIM, simulates Al diffusion in the coating to the growing oxide scale as well as Al diffusion into the substrate. The COSIM model incorporates an oxide growth and spalling model to provide the rate of Al consumption during cyclic oxidation. Coating failure is predicted when the Al concentration at the coating surface drops to a defined critical level. The modified COSIM model predicts the oxidative life of an overlay coating when a diffusion barrier is present eliminating diffusion of Al from the coating into the substrate. Both the original and the modified diffusion models have been used to predict the effectiveness of a diffusion barrier in extending the protective life of a NiCrAl overlay coating undergoing cyclic oxidation at 1100 C.

  17. Ground truth data generation for skull-face overlay.

    PubMed

    Ibáñez, O; Cavalli, F; Campomanes-Álvarez, B R; Campomanes-Álvarez, C; Valsecchi, A; Huete, M I

    2015-05-01

    Objective and unbiased validation studies over a significant number of cases are required to get a more solid picture on craniofacial superimposition reliability. It will not be possible to compare the performance of existing and upcoming methods for craniofacial superimposition without a common forensic database available for the research community. Skull-face overlay is a key task within craniofacial superimposition that has a direct influence on the subsequent task devoted to evaluate the skull-face relationships. In this work, we present the procedure to create for the first time such a dataset. We have also created a database with 19 skull-face overlay cases for which we are trying to overcome legal issues that allow us to make it public. The quantitative analysis made in the segmentation and registration stages, together with the visual assessment of the 19 face-to-face overlays, allows us to conclude that the results can be considered as a gold standard. With such a ground truth dataset, a new horizon is opened for the development of new automatic methods whose performance could be now objectively measured and compared against previous and future proposals. Additionally, other uses are expected to be explored to better understand the visual evaluation process of craniofacial relationships in craniofacial identification. It could be very useful also as a starting point for further studies on the prediction of the resulting facial morphology after corrective or reconstructive interventionism in maxillofacial surgery.

  18. An Overlapping Structured P2P for REIK Overlay Network

    NASA Astrophysics Data System (ADS)

    Liu, Wenjun; Song, Jingjing; Yu, Jiguo

    REIK is based on a ring which embedded an inverse Kautz digraph, to enable multi-path P2P routing. It has the constant degree and the logarithmic diameter DHT scheme with constant congestion and Byzantine fault tolerance. However, REIK did not consider the interconnection of many independent smaller networks. In this paper, we propose a new approach to build overlay network, OLS-REIK which is an overlapping structured P2P for REIK overlay network. It is a more flexible interconnecting different REIK network. Peers can belong to several rings, allowing this interconnection. By connecting smaller structured overlay networks in an unstructured way, it provides a cost effective alternative to hierarchical structured P2P systems requiring costly merging. Routing of lookup messages is performed as in REIK within one ring, but a peer belonging to several rings forwards the request to the different rings it belongs to. Furthermore a small number of across point is enough to ensure a high exhaustiveness level.

  19. HIGH-COMPRESSIVE-STRENGTH CONCRETE.

    DTIC Science & Technology

    CONCRETE , COMPRESSIVE PROPERTIES), PERFORMANCE(ENGINEERING), AGING(MATERIALS), MANUFACTURING, STRUCTURES, THERMAL PROPERTIES, CREEP, DEFORMATION, REINFORCED CONCRETE , MATHEMATICAL ANALYSIS, STRESSES, MIXTURES, TENSILE PROPERTIES

  20. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as the their capability to prevent or inhibit the attachment of marine fouling organisms to concrete. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6 1/2 years in seawater.

  1. Performance of Waterless Concrete

    NASA Technical Reports Server (NTRS)

    Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

    2010-01-01

    The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

  2. Antifouling marine concrete

    SciTech Connect

    Vind, H P; Mathews, C W

    1980-07-01

    Various toxic agents were evaluated as to their capability to prevent or inhibit the attachment of marine fouling organisms to concrete for OTEC plants. Creosote and bis-(tri-n-butyltin) oxide (TBTO) were impregnated into porous aggregate which was used in making concrete. Cuprous oxide, triphenyltin hydroxide (TPTH), and 2-2-bis-(p-methoxyphenyl)-1,1,1-trichloroethane (methoxychlor) were used as dry additives. Two proprietary formulations were applied as coatings on untreated concrete. Test specimens were exposed at Port Hueneme, CA, and Key Biscayne, FL. The efficacy of toxicants was determined by periodically weighing the adhering fouling organisms. Concrete prepared with an aggregate impregnated with a TBTO/creosote mixture has demonstrated the best antifouling performance of those specimens exposed for more than one year. The two proprietary coatings and the concrete containing methoxychlor, TPTH, and cuprous oxide as dry additives have exhibited good antifouling properties, but they have been exposed for a shorter time. The strength of concrete containing the toxicants was acceptable, and the toxicants did not increase the corrosion rate of reinforcing rods. Organotin compounds were essentially unchanged in concrete specimens exposed 6-1/2 years in seawater.

  3. Electrokinetic Strength Enhancement of Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry E. (Inventor)

    2016-01-01

    A method and apparatus for strengthening cementitious concrete by placing a nanoparticle carrier liquid in contact with a first surface of a concrete section and inducing a current across the concrete section at sufficient magnitude and for sufficient time that nanoparticles in the nanoparticle carrier liquid migrate through a significant depth of the concrete section.

  4. Electrokenitic Corrosion Treatment of Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry E (Inventor)

    2015-01-01

    A method and apparatus for strengthening cementitious concrete by placing a nanoparticle carrier liquid in contact with a first surface of a concrete section and inducing a current across the concrete section at sufficient magnitude and for sufficient time that nanoparticles in the nanoparticle carrier liquid migrate through a significant depth of the concrete section.

  5. Innovative fast technique for overlay accuracy estimation using archer self calibration (ASC)

    NASA Astrophysics Data System (ADS)

    Hsu, Simon C. C.; Chen, Charlie; Yu, Chun Chi; Pai, Yuan Chi; Amit, Eran; Yap, Lipkong; Itzkovich, Tal; Tien, David; Huang, Eros; Kuo, Kelly T. L.; Amir, Nuriel

    2014-04-01

    As overlay margins shrink for advanced process nodes, a key overlay metrology challenge is finding the measurement conditions which optimize the yield for every device and layer. Ideally, this setup should be found in-line during the lithography measurements step. Moreover, the overlay measurement must have excellent correlation to the device electrical behavior. This requirement makes the measurement conditions selection even more challenging since it requires information about the response of both the metrology target and device to different process variations. In this work a comprehensive solution for overlay metrology accuracy, used by UMC, is described. This solution ranks the different measurement setups by their accuracy, using Qmerit, as reported by the Archer 500. This ranking was verified to match device overlay using electrical tests. Moreover, the use of Archer Self Calibration (ASC) allows further improvement of overlay measurement accuracy.

  6. Corrosion-resistant sulfur concretes

    NASA Astrophysics Data System (ADS)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1983-04-01

    Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements. Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

  7. Permeability of Clay Concretes

    NASA Astrophysics Data System (ADS)

    Solomon, F.; Ekolu, S. O.

    2015-11-01

    This paper presents an investigation on the effect of clay addition on water permeability and air permeability of concretes. Clay concrete mixes consisted of 0 to 40% clay content incorporated as cement replacement. Flow methods using triaxial cells and air permeameters were used for measuring the injected water and air flows under pressure. It was found that the higher the clay content in the mixture, the greater the permeability. At higher water-cement ratios (w/c), the paste matrix is less dense and easily allows water to ingress into concrete. But at high clay contents of 30 to 40% clay, the variation in permeability was significantly diminished among different concrete mixtures. It was confirmed that air permeability results were higher than the corresponding water permeability values when all permeability coefficients were converted to intrinsic permeability values.

  8. Strengthening lightweight concrete

    NASA Technical Reports Server (NTRS)

    Auskern, A.

    1972-01-01

    Polymer absorption by lightweight concretes to improve bonding between cement and aggregate and to increase strength of cement is discussed. Compressive strength of treated cement is compared with strength of untreated product. Process for producing polymers is described.

  9. Bandwidth auction for SVC streaming in dynamic multi-overlay

    NASA Astrophysics Data System (ADS)

    Xiong, Yanting; Zou, Junni; Xiong, Hongkai

    2010-07-01

    In this paper, we study the optimal bandwidth allocation for scalable video coding (SVC) streaming in multiple overlays. We model the whole bandwidth request and distribution process as a set of decentralized auction games between the competing peers. For the upstream peer, a bandwidth allocation mechanism is introduced to maximize the aggregate revenue. For the downstream peer, a dynamic bidding strategy is proposed. It achieves maximum utility and efficient resource usage by collaborating with a content-aware layer dropping/adding strategy. Also, the convergence of the proposed auction games is theoretically proved. Experimental results show that the auction strategies can adapt to dynamic join of competing peers and video layers.

  10. Employing Multicast in P2P Overlay Networks

    NASA Astrophysics Data System (ADS)

    Kolberg, Mario

    The work on multicast has evolved from bottom IP layer multicast to Application Layer Multicast. While there are issues with the dep-loyment of IP layer multicast, it outperforms Application Layer Multicast. However, the latter has the advantage of an easier dep-loyment. Furthermore, as will be illustrated later in this Chapter, IP layer multicast has the potential to make parallel overlay operations more efficient. Application Layer Multicast is primarily used to send application specific messages/data to a number of nodes.

  11. Using overlay network architectures for scalable video distribution

    NASA Astrophysics Data System (ADS)

    Patrikakis, Charalampos Z.; Despotopoulos, Yannis; Fafali, Paraskevi; Cha, Jihun; Kim, Kyuheon

    2004-11-01

    Within the last years, the enormous growth of Internet based communication as well as the rapid increase of available processing power has lead to the widespread use of multimedia streaming as a means to convey information. This work aims at providing an open architecture designed to support scalable streaming to a large number of clients using application layer multicast. The architecture is based on media relay nodes that can be deployed transparently to any existing media distribution scheme, which can support media streamed using the RTP and RTSP protocols. The architecture is based on overlay networks at application level, featuring rate adaptation mechanisms for responding to network congestion.

  12. A Landau-Ginzburg Description of Sb Overlayers

    DTIC Science & Technology

    2001-04-01

    Heusler alloy NiMnSb is investigated in terms of the Landau-Ginzburg approach. The half -metallic semi- Heusler alloy NiMnSb acts as a ferromagnetic...NiMnSb layers covered by Sb overlayers. NiMnSb is a halfmetallic semi- Heusler alloy crystallizing in the cubic Cib structure. It may be considered as a...derivate of the parent Heusler alloy Ni2 MnSb and has a I band gap of less than about 0.5 eV [1]. Antimony is a semimetal characterized by a very small

  13. Ductile film delamination from compliant substrates using hard overlayers

    PubMed Central

    Cordill, M.J.; Marx, V.M.; Kirchlechner, C.

    2014-01-01

    Flexible electronic devices call for copper and gold metal films to adhere well to polymer substrates. Measuring the interfacial adhesion of these material systems is often challenging, requiring the formulation of different techniques and models. Presented here is a strategy to induce well defined areas of delamination to measure the adhesion of copper films on polyimide substrates. The technique utilizes a stressed overlayer and tensile straining to cause buckle formation. The described method allows one to examine the effects of thin adhesion layers used to improve the adhesion of flexible systems. PMID:25641995

  14. Shear Resistance between Concrete-Concrete Surfaces

    NASA Astrophysics Data System (ADS)

    Kovačovic, Marek

    2013-12-01

    The application of precast beams and cast-in-situ structural members cast at different times has been typical of bridges and buildings for many years. A load-bearing frame consists of a set of prestressed precast beams supported by columns and diaphragms joined with an additionally cast slab deck. This article is focused on the theoretical and experimental analyses of the shear resistance at an interface. The first part of the paper deals with the state-of-art knowledge of the composite behaviour of concrete-concrete structures and a comparison of the numerical methods introduced in the relevant standards. In the experimental part, a set of specimens with different interface treatments was tested until failure in order to predict the composite behaviour of coupled beams. The experimental part was compared to the numerical analysis performed by means of FEM basis nonlinear software.

  15. Infrared differential interference contrast microscopy for 3D interconnect overlay metrology.

    PubMed

    Ku, Yi-sha; Shyu, Deh-Ming; Lin, Yeou-Sung; Cho, Chia-Hung

    2013-08-12

    One of the main challenges for 3D interconnect metrology of bonded wafers is measuring through opaque silicon wafers using conventional optical microscopy. We demonstrate here the use infrared microscopy, enhanced by implementing the differential interference contrast (DIC) technique, to measure the wafer bonding overlay. A pair of two dimensional symmetric overlay marks were processed at both the front and back sides of thinned wafers to evaluate the bonding overlay. A self-developed analysis algorithm and theoretical fitting model was used to map the overlay error between the bonded wafers and the interconnect structures. The measurement accuracy was found to be better than 1.0 micron.

  16. Surface plasmon response of metal spherical nanoshells coated with dielectric overlayer

    NASA Astrophysics Data System (ADS)

    Cheng, Peihong; Bao, Jilong; Wu, Ligang; Li, Xue; Zhao, Hongxia; Zhu, Renxiang; Wang, Jinxia; Li, Dongsheng

    2013-11-01

    Surface Plasmon Resonance (SPR) characteristics of metal spherical nanoshells coated with different dielectric overlayers were investigated in this Letter. Besides band position, it is found that the line width of the symmetric dipole SP resonance is affected by the overlayer coating when the coupling strength of the inner surface cavity mode and outer surface sphere mode is strong. When the surrounding dielectric constant is comparative to that of core silica, narrowest damping width is expected. The computation results also demonstrate that the quality factors and electromagnetic field distribution are dependent on the overlayer coating. Consequently, an appropriate dielectric overlayer coating may be an important way of tuning SP characteristics of metal nanoshells.

  17. Performance of "Waterless Concrete"

    NASA Technical Reports Server (NTRS)

    Toutanji, H. A.; Grugel, R. N.

    2009-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

  18. Lightweight storage and overlay networks for fault tolerance.

    SciTech Connect

    Oldfield, Ron A.

    2010-01-01

    The next generation of capability-class, massively parallel processing (MPP) systems is expected to have hundreds of thousands to millions of processors, In such environments, it is critical to have fault-tolerance mechanisms, including checkpoint/restart, that scale with the size of applications and the percentage of the system on which the applications execute. For application-driven, periodic checkpoint operations, the state-of-the-art does not provide a scalable solution. For example, on today's massive-scale systems that execute applications which consume most of the memory of the employed compute nodes, checkpoint operations generate I/O that consumes nearly 80% of the total I/O usage. Motivated by this observation, this project aims to improve I/O performance for application-directed checkpoints through the use of lightweight storage architectures and overlay networks. Lightweight storage provide direct access to underlying storage devices. Overlay networks provide caching and processing capabilities in the compute-node fabric. The combination has potential to signifcantly reduce I/O overhead for large-scale applications. This report describes our combined efforts to model and understand overheads for application-directed checkpoints, as well as implementation and performance analysis of a checkpoint service that uses available compute nodes as a network cache for checkpoint operations.

  19. Dynamic bi-overlay rotation for streaming with heterogeneous devices

    NASA Astrophysics Data System (ADS)

    Liu, Dongyu; Chen, Songqing; Shen, Bo

    2008-01-01

    Recently Internet P2P/overlay streaming has gained increasing popularity. While plenty of research has focused on streaming performance study, it is not quite known yet on how to efficiently serve heterogeneous devices that have different limitations on display size, color depth, bandwidth capacities, CPU and battery power, than desktop computers. Although previous work1 proposes to reuse intermediate information (metadata) produced during transcoding to facilitate runtime content adaption to serve heterogeneous clients by reducing total computing load, unbalanced resource contribution may pre-maturely exhaust the limited power of mobile devices, and adversely affect the performance of participating nodes and subsequently threaten the robustness of the whole system. In this work, we propose a Dynamic Bi-Overlay Rotation (DOOR) scheme, in which, we further consider resource consumption of participating nodes to design a dynamic rotation scheme that reacts to dynamic situations and balances across multiple types of resources on individual nodes. Based on the computing load and transcoding quality parameters obtained through real transcoding sessions, we drive large scale simulations to evaluate DOOR. The results show clear improvement of DOOR over earlier work.

  20. Coded multiple chirp spread spectrum system and overlay service

    NASA Technical Reports Server (NTRS)

    Kim, Junghwan; Pratt, Timothy; Ha, Tri T.

    1988-01-01

    An asynchronous spread-spectrum system called coded multiple chirp is proposed, and the possible spread-spectrum overlay over an analog FM-TV signal is investigated by computer simulation. Multiple single-sloped up and down chirps are encoded by a pseudonoise code and decoded by dechirpers (pulse-compression filters) followed by a digital code correlator. The performance of the proposed system, expressed in terms of in probability of bit error and code miss probability, is similar to that of FSK (frequency shift keying) using codewords if sufficient compression gain is used. When chirp is used to overlay an FM-TV channel, two chirp signals with data rate up to 25 kb/s could be overlaid in a 36-MHz satellite transponder without significant mutual interference. Performance estimates for a VSAT (very small aperture terminal) earth station operating at C-band show that a 2.4-m antenna and 300-mW transmitter could send a 2.4-kb/s signal to a large central earth station over an occupied channel.

  1. Surface assessment and modification of concrete using abrasive blasting

    NASA Astrophysics Data System (ADS)

    Millman, Lauren R.

    Composite systems are applied to concrete substrates to strengthen and extend the service life. Successful restoration or rehabilitation requires surface preparation prior to the application of the overlay. Surface coatings, waterproofing systems, and other external surface applications also require surface preparation prior to application. Abrasive blast media is often used to clean and uniformly roughen the substrate. The appropriate surface roughness is necessary to facilitate a strong bond between the existing substrate and overlay. Thus, surface modification using abrasive blast media (sand and dry ice), their respective environmental effects, surface roughness characterization prior to and after blasting, and the adhesion between the substrate and overlay are the focus of this dissertation. This dissertation is comprised of an introduction, a literature review, and four chapters, the first of which addresses the environmental effects due to abrasive blasting using sand, water, and dry ice. The assessment considered four response variables: carbon dioxide (CO2) emissions, fuel and energy consumption, and project duration. The results indicated that for sand blasting and water jetting, the primary factor contributing to environmental detriment was CO22 emissions from vehicular traffic near the construction site. The second chapter is an analysis of the International Concrete Repair Institute's (ICRI) concrete surface profiles (CSPs) using 3-D optical profilometry. The primary objective was to evaluate the suitability of approximating the 3-D surface (areal) parameters with those extracted from 2-D (linear) profiles. Four profile directions were considered: two diagonals, and lines parallel and transverse to the longitudinal direction of the mold. For any CSP mold, the estimation of the 3-D surface roughness using a 2-D linear profile resulted in underestimation and overestimation errors exceeding 50%, demonstrating the inadequacy of 2-D linear profiles to

  2. Virtual overlay metrology for fault detection supported with integrated metrology and machine learning

    NASA Astrophysics Data System (ADS)

    Lee, Hong-Goo; Schmitt-Weaver, Emil; Kim, Min-Suk; Han, Sang-Jun; Kim, Myoung-Soo; Kwon, Won-Taik; Park, Sung-Ki; Ryan, Kevin; Theeuwes, Thomas; Sun, Kyu-Tae; Lim, Young-Wan; Slotboom, Daan; Kubis, Michael; Staecker, Jens

    2015-03-01

    While semiconductor manufacturing moves toward the 7nm node for logic and 15nm node for memory, an increased emphasis has been placed on reducing the influence known contributors have toward the on product overlay budget. With a machine learning technique known as function approximation, we use a neural network to gain insight to how known contributors, such as those collected with scanner metrology, influence the on product overlay budget. The result is a sufficiently trained function that can approximate overlay for all wafers exposed with the lithography system. As a real world application, inline metrology can be used to measure overlay for a few wafers while using the trained function to approximate overlay vector maps for the entire lot of wafers. With the approximated overlay vector maps for all wafers coming off the track, a process engineer can redirect wafers or lots with overlay signatures outside the standard population to offline metrology for excursion validation. With this added flexibility, engineers will be given more opportunities to catch wafers that need to be reworked, resulting in improved yield. The quality of the derived corrections from measured overlay metrology feedback can be improved using the approximated overlay to trigger, which wafers should or shouldn't be, measured inline. As a development or integration engineer the approximated overlay can be used to gain insight into lots and wafers used for design of experiments (DOE) troubleshooting. In this paper we will present the results of a case study that follows the machine learning function approximation approach to data analysis, with production overlay measured on an inline metrology system at SK hynix.

  3. 26. Evening view of concrete mixing plant, concrete placement tower, ...

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

    26. Evening view of concrete mixing plant, concrete placement tower, cableway tower, power line and derrick. Photographer unknown, 1927. Source: MWD. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  4. Viral Concentration Determination Through Plaque Assays: Using Traditional and Novel Overlay Systems

    PubMed Central

    Baer, Alan; Kehn-Hall, Kylene

    2014-01-01

    Plaque assays remain one of the most accurate methods for the direct quantification of infectious virons and antiviral substances through the counting of discrete plaques (infectious units and cellular dead zones) in cell culture. Here we demonstrate how to perform a basic plaque assay, and how differing overlays and techniques can affect plaque formation and production. Typically solid or semisolid overlay substrates, such as agarose or carboxymethyl cellulose, have been used to restrict viral spread, preventing indiscriminate infection through the liquid growth medium. Immobilized overlays restrict cellular infection to the immediately surrounding monolayer, allowing the formation of discrete countable foci and subsequent plaque formation. To overcome the difficulties inherent in using traditional overlays, a novel liquid overlay utilizing microcrystalline cellulose and carboxymethyl cellulose sodium has been increasingly used as a replacement in the standard plaque assay. Liquid overlay plaque assays can be readily performed in either standard 6 or 12 well plate formats as per traditional techniques and require no special equipment. Due to its liquid state and subsequent ease of application and removal, microculture plate formats may alternatively be utilized as a rapid, accurate and high throughput alternative to larger scale viral titrations. Use of a non heated viscous liquid polymer offers the opportunity to streamline work, conserves reagents, incubator space, and increases operational safety when used in traditional or high containment labs as no reagent heating or glassware are required. Liquid overlays may also prove more sensitive than traditional overlays for certain heat labile viruses. PMID:25407402

  5. Questioning the Benefits That Coloured Overlays Can Have for Reading in Students with and without Dyslexia

    ERIC Educational Resources Information Center

    Henderson, Lisa M.; Tsogka, Natassa; Snowling, Margaret J.

    2013-01-01

    Visual stress (the experience of visual distortions and discomfort during prolonged reading) is frequently identified and alleviated with coloured overlays or lenses. Previous studies have associated visual stress with dyslexia and as a consequence, coloured overlays are widely distributed to children and adults with reading difficulty. However,…

  6. Techniques for improving overlay accuracy by using device correlated metrology targets as reference

    NASA Astrophysics Data System (ADS)

    Tzai, Wei Jhe; Hsu, Simon C. C.; Chen, Howard; Chen, Charlie; Pai, Yuan Chi; Yu, Chun-Chi; Lin, Chia Ching; Itzkovich, Tal; Yap, Lipkong; Amit, Eran; Tien, David; Huang, Eros; Kuo, Kelly T. L.; Amir, Nuriel

    2014-10-01

    The performance of overlay metrology as total measurement uncertainty, design rule compatibility, device correlation, and measurement accuracy has been challenged at the 2× nm node and below. The process impact on overlay metrology is becoming critical, and techniques to improve measurement accuracy become increasingly important. We present a methodology for improving the overlay accuracy. A propriety quality metric, Qmerit, is used to identify overlay metrology measurement settings with the least process impacts and reliable accuracies. Using the quality metric, a calibration method, Archer self-calibration, is then used to remove the inaccuracies. Accuracy validation can be achieved by correlation to reference overlay data from another independent metrology source such as critical dimension-scanning electron microscopy data collected on a device correlated metrology hybrid target or by electrical testing. Additionally, reference metrology can also be used to verify which measurement conditions are the most accurate. We provide an example of such a case.

  7. Innovative techniques for improving overlay accuracy by using DCM (device correlated metrology) targets as reference

    NASA Astrophysics Data System (ADS)

    Tzai, Wei-Jhe; Hsu, Simon C. C.; Chen, Howard; Chen, Charlie; Pai, Yuan Chi; Yu, Chun-Chi; Lin, Chia Ching; Itzkovich, Tal; Yap, Lipkong; Amit, Eran; Tien, David; Huang, Eros; Kuo, Kelly T. L.; Amir, Nuriel

    2014-04-01

    Overlay metrology performance as Total Measurement Uncertainty (TMU), design rule compatibility, device correlation and measurement accuracy are been challenged at 2x nm node and below. Process impact on overlay metrology becoming critical, and techniques to improve measurement accuracy becomes increasingly important. In this paper, we present an innovative methodology for improving overlay accuracy. A propriety quality metric, Qmerit, is used to identify overlay metrology measurement settings with least process impacts and reliable accuracies. Using the quality metric, an innovative calibration method, ASC (Archer Self Calibration) is then used to remove the inaccuracies. Accuracy validation can be achieved by correlation to reference overlay data from another independent metrology source such as CDSEM data collected on DCM (Device Correlated Metrology) hybrid target or electrical testing. Additionally, reference metrology can also be used to verify which measurement conditions are the most accurate. In this paper we bring an example of such use case.

  8. Electrokinetic decontamination of concrete

    SciTech Connect

    Lomasney, H.

    1995-10-01

    The U.S. Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes an electropotential gradient and the subsequent electrical transport mechanism to cause the controlled movement of ionics species, whereby the contaminants exit the recesses deep within the concrete. This report discusses the technology and use at the Oak Ridge k-25 plant.

  9. Structural Materials: 95. Concrete

    SciTech Connect

    Naus, Dan J

    2012-01-01

    Nuclear power plant concrete structures and their materials of construction are described, and their operating experience noted. Aging and environmental factors that can affect the durability of the concrete structures are identified. Basic components of a program to manage aging of these structures are identified and described. Application of structural reliability theory to devise uniform risk-based criteria by which existing facilities can be evaluated to achieve a desired performance level when subjected to uncertain demands and to quantify the effects of degradation is outlined. Finally, several areas are identified where additional research is desired.

  10. ECHO: a community video streaming system with interactive visual overlays

    NASA Astrophysics Data System (ADS)

    Cheung, Gene; Tan, Wai-tian; Shen, Bo; Ortega, Antonio

    2008-01-01

    We describe a networked video application where personalized avatars, controlled by a group of "hecklers", are overlaid on top of a real-time encoded video stream of an Internet game for multicast consumption. Rather than passively observing the streamed content individually, the interactivity of the controllable avatars, along with heckling voice exchange, engenders a sense of community during group viewing. We first describe how the system splits video into independent regions with and without avatars for processing in order to minimize complexity. Observing that the region with avatars is more delay-sensitive due to their interactivity, we then show that the regions can be logically packetized into separable sub-streams, and be transported and buffered with different delay requirements, so that the interactivity of the avatars can be maximized. The utility of our system extends beyond Internet game watching to general community streaming of live or pre-encoded video with visual overlays.

  11. Ubiquitous map-image access through wireless overlay networks

    NASA Astrophysics Data System (ADS)

    Cai, Jianfei; Huang, Haijie; Ni, Zefeng; Chen, Chang Wen

    2004-10-01

    With the availability of various wireless link-layer technologies, such as Bluetooth, WLAN and GPRS, in one wireless device, ubiquitous communications can be realized through managing vertical handoff in the environment of wireless overlay networks. In this paper, we propose a vertical handoff management system based on mobile IPv6, which can automatically manage the multiple network interfaces on the mobile device, and make decisions on network interface selection according to the current situation. Moreover, we apply our proposed vertical handoff management with JPEG-2000 codec to the wireless application of map image access. The developed system is able to provide seamless communications, as well as fast retrieve any interested map region with any block size, in different resolutions and different color representations directly from the compressed bitstream.

  12. The Pegasus Overture alternating-pressure mattress overlay.

    PubMed

    Fox, C

    Pressure sores affect approximately 10% of the adult population and occur in various hospitals and community settings (Department of Health, 1992). It is therefore essential to adopt a logical approach when selecting the optimum piece of equipment for patients at risk of pressure sore development. Alternating-pressure mattresses have been used for many years in both hospitals and community environments to prevent and treat pressure sores. In September 1995, Pegasus Airwave Limited launched a new alternating-pressure mattress overlay, the Overture. It is designed for use with patients who have mobility problems and are at low to medium risk of developing pressure sores or have superficial tissue damage. This article describes the features of the Overture and its suitability for use in different care settings.

  13. Pressure reduction with a hospitalized population using a mattress overlay.

    PubMed

    Suarez, C H; Reynolds, A

    1995-01-01

    Billions of dollars are spent each year on treating pressure ulcers. With healthcare costs climbing and reform the order of the day, it is essential for researchers to identify a device which reduces pressure, is easy to use and is cost effective. This study used a Mini-Tipe pressure sensor to measure pressure readings over the sacral and trochanter areas of 17 subjects identified as being at risk for skin breakdown. Pressures were compared on a standard hospital mattress and an anatomically contoured mattress overlay. There was a 48 percent reduction in mean pressures over the sacral area and a 23 percent reduction over the trochanter. No correlations between pressures and demographic data were identified. Further research is warranted to determine the effects of variables found in an "at risk" population on pressure reduction with various products.

  14. Computer vision and soft computing for automatic skull-face overlay in craniofacial superimposition.

    PubMed

    Campomanes-Álvarez, B Rosario; Ibáñez, O; Navarro, F; Alemán, I; Botella, M; Damas, S; Cordón, O

    2014-12-01

    Craniofacial superimposition can provide evidence to support that some human skeletal remains belong or not to a missing person. It involves the process of overlaying a skull with a number of ante mortem images of an individual and the analysis of their morphological correspondence. Within the craniofacial superimposition process, the skull-face overlay stage just focuses on achieving the best possible overlay of the skull and a single ante mortem image of the suspect. Although craniofacial superimposition has been in use for over a century, skull-face overlay is still applied by means of a trial-and-error approach without an automatic method. Practitioners finish the process once they consider that a good enough overlay has been attained. Hence, skull-face overlay is a very challenging, subjective, error prone, and time consuming part of the whole process. Though the numerical assessment of the method quality has not been achieved yet, computer vision and soft computing arise as powerful tools to automate it, dramatically reducing the time taken by the expert and obtaining an unbiased overlay result. In this manuscript, we justify and analyze the use of these techniques to properly model the skull-face overlay problem. We also present the automatic technical procedure we have developed using these computational methods and show the four overlays obtained in two craniofacial superimposition cases. This automatic procedure can be thus considered as a tool to aid forensic anthropologists to develop the skull-face overlay, automating and avoiding subjectivity of the most tedious task within craniofacial superimposition.

  15. Accuracy of overlay measurements: tool and mark asymmetry effects

    NASA Astrophysics Data System (ADS)

    Coleman, Daniel J.; Larson, Patricia J.; Lopata, Alexander D.; Muth, William A.; Starikov, Alexander

    1990-06-01

    Results of recent Investigations uncovering significant errors in overlay (O/L) measurements are reported. The two major contributors are related to the failures of symmetry of the overlay measurement tool and of the mark. These may result In measurement errors on the order of 100 nm. Methodology based on the conscientious verification of assumptions of symmetry is shown to be effective in identifying the extent and sources of such errors. This methodology can be used to arrive at an estimate of the relative accuracy of the O/L measurements, even in absence of certified O/L reference materials. Routes to improve the accuracy of O/L measurements are outlined and some examples of improvements are given. Errors in O/L measurements associated with the asymmetry of the metrology tool can be observed by comparing the O/L measurements taken at 0 and 180 degree orientations of the sample in reference to the tool. Half the difference of these measurements serves as an estimate of such tool related bias in estimating O/L. This is called tool induced shift (TIS). Errors of this kind can be traced to asymmetries of tool components, e. g., camera, illumination misalignment, residual asymmetric aberrations etc. Tool asymmetry leads to biased O/L estimates even on symmetric O/L measurement marks. Its impact on TIS depends on the optical properties of the structure being measured, the measurement procedure and on the combination of tool and sample asymmetries. It is also a function of design and manufacture of the O/L metrology tool. In the absence of certified O/L samples, measurement accuracy and repeatability may be improved by demanding that TIS be small for all tools on all structures.

  16. Precast Concrete Pavements

    DTIC Science & Technology

    1981-11-01

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

  17. High temperature polymer concrete

    DOEpatents

    Fontana, J.J.; Reams, W.

    1984-05-29

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system.

  18. Concrete Block Pavements

    DTIC Science & Technology

    1983-03-01

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

  19. Heidrun concrete TLP: Update

    SciTech Connect

    Munkejord, T.

    1995-10-01

    This paper gives a summary of the Heidrun substructure including tethers and foundations. The focus will although be on the concrete substructure. The Heidrun Field is located in 345 m water depth in the northern part of the Haltenbanken area, approximately 100N miles from the west coast of mid-Norway. The field is developed by means of a concrete Tension Leg Platform (TLP) by Conoco Norway Inc. The TLP will be moored by 16 steel tethers, arranged in groups of four per corner, which secure the substructure (hull) to the concrete foundations. A general view of the TLP is shown. The Heidrun TLP will be the northern most located platform in the North Sea when installed at Haltenbanken in 1995. Norwegian Contractors a.s (NC) is undertaking the Engineering, Procurement, Construction and Installation (EPCI) contract for the Heidrun TLP substructure. This comprises the complete delivery of the hull with two module support beams (MSB), including all mechanical outfitting. Furthermore, NC will perform all marine operations related to the substructure. For the concrete foundations NC has performed the detailed engineering work and has been responsible for the two to field and installation of the foundations.

  20. Micromechanics of Concrete.

    DTIC Science & Technology

    1988-01-25

    reflects the dispersion of the coarse aggregates on the mesoscale. Specifically, the experimental measure- ments indicate ( Mindess and Young 1981, Zaitsev...Mecanique des Materiaux Solides, Dunod, Paris. Mindess , S. and J. Young (1981), Concrete, Prentice-Hall Inc., Englewood Cliffs, NJ. Mura, T. (1982

  1. Diffraction based overlay metrology: accuracy and performance on front end stack

    NASA Astrophysics Data System (ADS)

    Leray, Philippe; Cheng, Shaunee; Kandel, Daniel; Adel, Michael; Marchelli, Anat; Vakshtein, Irina; Vasconi, Mauro; Salski, Bartlomiej

    2008-03-01

    The overlay metrology budget is typically 1/10 of the overlay control budget resulting in overlay metrology total measurement uncertainty requirements of 0.57 nm for the most challenging use cases of the 32nm technology generation. Theoretical considerations show that overlay technology based on differential signal scatterometry (SCOL TM) has inherent advantages, which will allow it to achieve the 32nm technology generation requirements and go beyond it. In this work we present results of an experimental and theoretical study of SCOL. We present experimental results, comparing this technology with the standard imaging overlay metrology. In particular, we present performance results, such as precision and tool induced shift, for different target designs. The response to a large range of induced misalignment is also shown. SCOL performance on these targets for a real stack is reported. We also show results of simulations of the expected accuracy and performance associated with a variety of scatterometry overlay target designs. The simulations were carried out on several stacks including FEOL and BEOL materials. The inherent limitations and possible improvements of the SCOL technology are discussed. We show that with the appropriate target design and algorithms, scatterometry overlay achieves the accuracy required for future technology generations.

  2. Tighter process control of poly- and active-to-contact overlay registration via multilayer analysis

    NASA Astrophysics Data System (ADS)

    Lee, Peter M. C.; Knutrud, Paul C.

    2000-06-01

    As process technology in high volume production fabs hits the 180 nm window, overlay metrology of the most critical layers needs to be managed very carefully. As feature sizes and other device characteristics shrink, the overlay requirement becomes a larger component of the overall process specification. It is no longer sufficient to measure overlay for only two layers at a time. In no other part of the process is this more critical than the poly and active layer to first contact. The contact layer needs to be aligned to both active and poly within tight tolerances. Since adjustments to overlay for these levels are not independent, it is essential to understand the relationship between all three layers. TSMC in particular, because it is a foundry, is not able to optimize customer circuit design that would allow two-layer registration to be sufficient. Previously, the only method to accomplish this has been to make two sets of overlay measurements and having an engineer analyze the relative overlay between the three layers. The proposed solution to solve this problem is a multi-layer overlay measurement algorithm and measurement target. This paper will report on the analysis of the process improvements that have and can be achieved using this unique measurement capability.

  3. The Growth of Metal Overlayers on Oxide Surfaces.

    NASA Astrophysics Data System (ADS)

    Mayer, Jeffrey Thomas

    1995-01-01

    The structural and chemical properties of metals on oxides have been analyzed by examining two very different adsorption systems. The first, Ni/SiO_2 , is representative of systems with a rather weak interaction between the metal overlayer and oxide substrate. The second system analyzed, Ti/TiO_2, is an example with very strong reactive adsorbate/substrate interaction. The surface and interface behavior of both systems are investigated using basic thermodynamic and kinetic concepts. The surface diffusion of nickel on a thermally -grown silicon dioxide thin film (5-50A), and the bulk diffusion of Ni through the SiO_2 film into the single crystal silicon substrate have been studied by x-ray photoelectron spectroscopy (XPS), high resolution electron energy loss spectroscopy (HREELS), low energy electron diffraction (LEED), and atomic force microscopy (AFM). Nickel agglomeration on the oxide occurs in the 100-850K regime, while bulk Ni diffusion through the thin oxide layer occurs in the 700-1050K regime. The onset of bulk Ni diffusion is dependent on oxide thickness; thicker oxides reduce the rate of Ni penetration. Above 950-1100K, the oxide desorbs leaving nickel disilicide on silicon. The study of nickel disilicide island formation on Si(111) (an outgrowth of the Ni/SiO_2 experiments) is reported. The kinetics of this system control a rather interesting series of metastable growth structures. Visually striking NiSi_2 crystallites are observed on the Si(111) surface by AFM. The nickel disilicide islands coalesce following a high temperature anneal (~1260K). The islands differ from those formed at lower temperature in both shape and orientation. These differences are explained by kinetically limited growth accompanying phase and surface segregation of Ni from the bulk silicon wafer, and condensation of a Ni-rich NiSi_{rm 2-x} liquid phase at the surface. Condensation from the liquid phase to NiSi_2 is concluded to be responsible for the structure of the crystallites

  4. Influence of the process-induced asymmetry on the accuracy of overlay measurements

    NASA Astrophysics Data System (ADS)

    Shapoval, Tetyana; Schulz, Bernd; Itzkovich, Tal; Durran, Sean; Haupt, Ronny; Cangiano, Agostino; Bringoltz, Barak; Ruhm, Matthias; Cotte, Eric; Seltmann, Rolf; Hertzsch, Tino; Hajaj, Eitan; Hartig, Carsten; Efraty, Boris; Fischer, Daniel

    2015-03-01

    In the current paper we are addressing three questions relevant for accuracy: 1. Which target design has the best performance and depicts the behavior of the actual device? 2. Which metrology signal characteristics could help to distinguish between the target asymmetry related overlay shift and the real process related shift? 3. How does uncompensated asymmetry of the reference layer target, generated during after-litho processes, affect the propagation of overlay error through different layers? We are presenting the correlation between simulation data based on the optical properties of the measured stack and KLA-Tencor's Archer overlay measurements on a 28nm product through several critical layers for those accuracy aspects.

  5. Prosthodontic management of worn dentition in pediatric patient with complete overlay dentures: a case report

    PubMed Central

    Rastogi, Jyoti; Jain, Chandni; Singh, Harkanwal Preet

    2012-01-01

    Overlay complete dentures are simple, reversible and economical treatment modality for patients with congenital or acquired disorders that severely affect the tooth development. It satisfies both the esthetic and functional demands where the extraction of teeth is not generally indicated. In pediatric patients, the overlay dentures establish a relatively stable occlusion that improves patient's tolerance to the future treatment procedures for worn dentition. This clinical report highlights the imperative need of appropriate treatment strategy and application of maxillary and mandibular overlay dentures in a pediatric patient who suffered from congenitally mutilated and worn dentition. PMID:23236577

  6. Overlay target selection for 20-nm process on A500 LCM

    NASA Astrophysics Data System (ADS)

    Ramanathan, Vidya; Subramany, Lokesh; Itzkovich, Tal; Gutjhar, Karsten; Snow, Patrick; Cho, Chanseob; Yap, Lipkong

    2015-03-01

    Persistently shrinking design rules and increasing process complexity require tight overlay control thereby making it imperative to choose the most suitable overlay measurement technique and complementary target design. In this paper we describe an assessment of various target designs from FEOL to BEOL on 20-nm process. Both scatterometry and imaging based methodology were reviewed for several key layers on A500LCM tool, which enables the use of both technologies. Different sets of targets were carefully designed and printed, taking into consideration the process and optical properties of each layer. The optimal overlay target for a given layer was chosen based on its measurement performance.

  7. Concrete lunar base investigation

    NASA Technical Reports Server (NTRS)

    Lin, T. D.; Senseney, Jonathan A.; Arp, Larry Dean; Lindbergh, Charles

    1989-01-01

    This paper presents results of structural analyses and a preliminary design of a precast, prestressed concrete lunar based subjected to one atmosphere internal pressure. The proposed infrastructure measures 120 ft in diameter and 72 ft in height, providing 33,000 sq ft of work area for scientific and industrial operations. Three loading conditions were considered in the design: (1) during construction; (2) under pressurization; and (3) during an air-leak scenario. A floating foundation, capable of rigid body rotation and translation as the lunar soil beneath it yields, was developed to support the infrastructure and to ensure the air-tightness of the system. Results reveal that it is feasible to use precast, prestressed concrete for construction of large lunar bases on the moon.

  8. Concrete lunar base investigation

    NASA Technical Reports Server (NTRS)

    Lin, T. D.; Senseny, Jonathan A.; Arp, Larry D.; Lindbergh, Charles

    1992-01-01

    This paper presents results of structural analyses and a preliminary design of a precast, prestressed concrete lunar base subjected to 1-atm internal pressure. The proposed infrastructure measures 120 ft in diameter and 72 ft in height, providing 33,000 sq ft of work area for scientific and industrial operations. Three loading conditions were considered in the design (1) during construction, (2) under pressurization, and (3) during an air-leak scenario. A floating foundation, capable of rigid body rotation and translation as the lunar soil beneath it yields, was developed to support the infrastructure and to ensure the airtightness of the system. Results reveal that it is feasible to use precast, prestressed concrete for construction of large lunar bases on the Moon.

  9. Penetration of concrete targets

    SciTech Connect

    Forrestal, M.J.; Cargile, J.D.; Tzou, R.D.Y.

    1993-08-01

    We developed penetration equations for ogive-nosed projectiles that penetrated concrete targets after normal impact. Our penetration equations predict axial force on the projectile nose, rigid-body motion, and final penetration depth. For target constitutive models, we conducted triaxial material experiments to confining pressures of 600 MPa and curve-fit these data with a linear pressure-volumetric strain relation and with a linear Mohr-Coulomb, shear strength-pressure relation. To verify our penetration equations, we conducted eleven penetration experiments with 0.90 kg, 26.9-mm-diameter, ogive-nosed projectiles into 1.37-m-diameter concrete targets with unconfined compressive strengths between 32-40 MPa. Predictions from our penetration equation are compared with final penetration depth measurements for striking velocities between 280--800 m/s.

  10. Concrete containment aging study

    SciTech Connect

    Pachner, J.; Tai, T.M.; Naus, D.

    1994-04-01

    In 1989, IAEA initiated a pilot study on the management of aging of nuclear power plant components. The Phase I and II studies of concrete containment are discussed. With the data base, plant owners will be able to review and enhance their existing programs. IAEA will analyze data provided by participating plants and the report is scheduled to be released by late 1994 (final report release mid-1995).

  11. Mechanics of Concrete II

    DTIC Science & Technology

    1990-10-18

    diffusivity of undamaged concrete is a problem in itself since the diffusivity of the thin transition zones (at the aggregate- cement matrix interface...C3A anhydride remains in the cement after the hydration. Assuming that the amount of gypsum added to portland cement3 clinker is 4% of Mcm (Biczok 1972...enables establishment of rational relationships between the chemical composition of the hardened cement paste, morphology of the pore system, and defect

  12. Tonsil concretions and tonsilloliths.

    PubMed

    Pruet, C W; Duplan, D A

    1987-05-01

    Although infrequently seen in many clinical practices, tonsillar concretions can be the source of both fetor oris and physical and social concern for the patient. Though stones rarely form in the tonsil or peritonsillar area, the findings of calcified objects or stones anywhere within the body has long been a subject of interest. The salient features of these entities and their relevance to clinical practice are discussed in this article.

  13. Nondestructive Concrete Characterization System

    DTIC Science & Technology

    2013-05-20

    Park, NC 27709-2211 15. SUBJECT TERMS Ultrasonic Pulse Velocity (UPV), Impact-Echo, Ultrasonic Pulse-Echo, Ultrasonic Attenuation, STTR Report Aldo... ultrasonic testing in conjunction with the resonance frequency. All results were within the specified tolerance of ±1 ft. The compressive strength of the...concrete blocks was measured by measuring the P-wave and S-wave time of travel with the pitch-catch method of ultrasonic testing. All results were

  14. Ultrasonic Evaluation of Two Dissimilar Metal Weld Overlay Specimens

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Prowant, Matthew S.; Moran, Traci L.; Anderson, Michael T.

    2012-06-30

    Two dissimilar metal weld (DMW) pipe-to-nozzle specimens were implanted with thermal fatigue cracks in the 13% to 90% through-wall depth range. The specimens were ultrasonically evaluated with phased-array probes having center frequencies of 0.8, 1.0, 1.5, and 2.0 megahertz (MHz). An Alloy 82/182 weld overlay (WOL) was applied and the specimens were ultrasonically re-evaluated for flaw detection and characterization. The Post-WOL flaw depths were approximately 10% to 56% through-wall. This study has shown the effectiveness of ultrasonic examinations of Alloy 82/182 overlaid DMW specimens. Phased-array probes with center frequency in the 0.8- to 1.0-MHz range provide a strong coherent signal but the greater ultrasonic wavelength and larger beam spot size prevent the reliable detection of small flaws. These small flaws had nominal through-wall depths of less than 15% and length in the 50-60 mm (2-2.4 in.) range. Flaws in the 19% and greater through-wall depth range were readily detected with all four probes. At the higher frequencies, the reflected signals are less coherent but still provide adequate signal for flaw detection and characterization. A single inspection at 2.0 MHz could provide adequate detection and sizing information but a supplemental inspection at 1.0 or 1.5 MHz is recommended.

  15. Quality metric for accurate overlay control in <20nm nodes

    NASA Astrophysics Data System (ADS)

    Klein, Dana; Amit, Eran; Cohen, Guy; Amir, Nuriel; Har-Zvi, Michael; Huang, Chin-Chou Kevin; Karur-Shanmugam, Ramkumar; Pierson, Bill; Kato, Cindy; Kurita, Hiroyuki

    2013-04-01

    The semiconductor industry is moving toward 20nm nodes and below. As the Overlay (OVL) budget is getting tighter at these advanced nodes, the importance in the accuracy in each nanometer of OVL error is critical. When process owners select OVL targets and methods for their process, they must do it wisely; otherwise the reported OVL could be inaccurate, resulting in yield loss. The same problem can occur when the target sampling map is chosen incorrectly, consisting of asymmetric targets that will cause biased correctable terms and a corrupted wafer. Total measurement uncertainty (TMU) is the main parameter that process owners use when choosing an OVL target per layer. Going towards the 20nm nodes and below, TMU will not be enough for accurate OVL control. KLA-Tencor has introduced a quality score named `Qmerit' for its imaging based OVL (IBO) targets, which is obtained on the-fly for each OVL measurement point in X & Y. This Qmerit score will enable the process owners to select compatible targets which provide accurate OVL values for their process and thereby improve their yield. Together with K-T Analyzer's ability to detect the symmetric targets across the wafer and within the field, the Archer tools will continue to provide an independent, reliable measurement of OVL error into the next advanced nodes, enabling fabs to manufacture devices that meet their tight OVL error budgets.

  16. Augmented Endoscopic Images Overlaying Shape Changes in Bone Cutting Procedures.

    PubMed

    Nakao, Megumi; Endo, Shota; Nakao, Shinichi; Yoshida, Munehito; Matsuda, Tetsuya

    2016-01-01

    In microendoscopic discectomy for spinal disorders, bone cutting procedures are performed in tight spaces while observing a small portion of the target structures. Although optical tracking systems are able to measure the tip of the surgical tool during surgery, the poor shape information available during surgery makes accurate cutting difficult, even if preoperative computed tomography and magnetic resonance images are used for reference. Shape estimation and visualization of the target structures are essential for accurate cutting. However, time-varying shape changes during cutting procedures are still challenging issues for intraoperative navigation. This paper introduces a concept of endoscopic image augmentation that overlays shape changes to support bone cutting procedures. This framework handles the history of the location of the measured drill tip as a volume label and visualizes the remains to be cut overlaid on the endoscopic image in real time. A cutting experiment was performed with volunteers, and the feasibility of this concept was examined using a clinical navigation system. The efficacy of the cutting aid was evaluated with respect to the shape similarity, total moved distance of a cutting tool, and required cutting time. The results of the experiments showed that cutting performance was significantly improved by the proposed framework.

  17. Augmented Endoscopic Images Overlaying Shape Changes in Bone Cutting Procedures

    PubMed Central

    2016-01-01

    In microendoscopic discectomy for spinal disorders, bone cutting procedures are performed in tight spaces while observing a small portion of the target structures. Although optical tracking systems are able to measure the tip of the surgical tool during surgery, the poor shape information available during surgery makes accurate cutting difficult, even if preoperative computed tomography and magnetic resonance images are used for reference. Shape estimation and visualization of the target structures are essential for accurate cutting. However, time-varying shape changes during cutting procedures are still challenging issues for intraoperative navigation. This paper introduces a concept of endoscopic image augmentation that overlays shape changes to support bone cutting procedures. This framework handles the history of the location of the measured drill tip as a volume label and visualizes the remains to be cut overlaid on the endoscopic image in real time. A cutting experiment was performed with volunteers, and the feasibility of this concept was examined using a clinical navigation system. The efficacy of the cutting aid was evaluated with respect to the shape similarity, total moved distance of a cutting tool, and required cutting time. The results of the experiments showed that cutting performance was significantly improved by the proposed framework. PMID:27584732

  18. A genetic algorithm for flexible molecular overlay and pharmacophore elucidation

    NASA Astrophysics Data System (ADS)

    Jones, Gareth; Willett, Peter; Glen, Robert C.

    1995-12-01

    A genetic algorithm (GA) has been developed for the superimposition of sets of flexible molecules. Molecules are represented by a chromosome that encodes angles of rotation about flexible bonds and mappings between hydrogen-bond donor proton, acceptor lone pair and ring centre features in pairs of molecules. The molecule with the smallest number of features in the data set is used as a template, onto which the remaining molecules are fitted with the objective of maximising structural equivalences. The fitness function of the GA is a weighted combination of: (i) the number and the similarity of the features that have been overlaid in this way; (ii) the volume integral of the overlay; and (iii) the van der Waals energy of the molecular conformations defined by the torsion angles encoded in the chromosomes. The algorithm has been applied to a number of pharmacophore elucidation problems, i.e., angiotensin II receptor antagonists, Leu-enkephalin and a hybrid morphine molecule, 5-HT1D agonists, benzodiazepine receptor ligands, 5-HT3 antagonists, dopamine D2 antagonists, dopamine reuptake blockers and FKBP12 ligands. The resulting pharmacophores are generated rapidly and are in good agreement with those derived from alternative means.

  19. RelEx: Visualization for Actively Changing Overlay Network Specifications.

    PubMed

    Sedlmair, M; Frank, A; Munzner, T; Butz, A

    2012-12-01

    We present a network visualization design study focused on supporting automotive engineers who need to specify and optimize traffic patterns for in-car communication networks. The task and data abstractions that we derived support actively making changes to an overlay network, where logical communication specifications must be mapped to an underlying physical network. These abstractions are very different from the dominant use case in visual network analysis, namely identifying clusters and central nodes, that stems from the domain of social network analysis. Our visualization tool RelEx was created and iteratively refined through a full user-centered design process that included a full problem characterization phase before tool design began, paper prototyping, iterative refinement in close collaboration with expert users for formative evaluation, deployment in the field with real analysts using their own data, usability testing with non-expert users, and summative evaluation at the end of the deployment. In the summative post-deployment study, which entailed domain experts using the tool over several weeks in their daily practice, we documented many examples where the use of RelEx simplified or sped up their work compared to previous practices.

  20. A comparison of alignment and overlay performance with varying hardmask materials

    NASA Astrophysics Data System (ADS)

    Yun, Sangho; Ha, Soon Mok; Nam, Young Min; Kim, Cheol-Hong; Nam, Suk-Woo

    2012-03-01

    In recent semiconductor manufacturing, hardmask is unavoidable requirement to further transfer the patterning from thin photoresist to underlayer. While several types of hardmask materials have been investigated, amorphous carbon has been attractive for good etching resistance and high-aspect-ratio resolution. However, it has fatal problem with lowering overlay controllability due to its high extinction coefficient (k). Thus, the correlation of alignment and overlay performance with varying hardmask materials is required to meet a tight overlay budget of 2x nm node and beyond. In this paper, we have investigated the effects of the hardmask materials with respect to the optical properties on the performance of overlay applicable to 2x nm memory devices.

  1. A Preliminary Study of Building a Transmission Overlay for Regional US Power Grid

    SciTech Connect

    Lei, Yin; Li, Yalong; Liu, Yilu; Tomsovic, Kevin; Wang, Fei

    2015-01-01

    Many European countries have taken steps toward a Supergrid in order to transmit large amount of intermittent and remote renewable energy over long distance to load centers. In the US, as the expected increase in renewable generation and electricity demand, similar problem arises. A potential solution is to upgrade the transmission system at a higher voltage by constructing a new overlay grid. This paper will first address basic requirements for such an overlay grid. Potential transmission technologies will also be discussed. A multi-terminal VSC HVDC model is developed in DSATools to implement the overlay grid and a test case on a regional NPCC system will be simulated. Another test system of entire US power grid, with three different interconnections tied together using back-to-back HVDC, is also introduced in this paper. Building an overlay system on top of this test case is ongoing, and will be discussed in future work.

  2. Modification of the perpendicular magnetic anisotropy of ultrathin Co films due to the presence of overlayers

    NASA Astrophysics Data System (ADS)

    Park, Sungkyun; Lee, Sukmock; Falco, Charles M.

    2002-05-01

    In order to understand the effect of interfacial strain on perpendicular magnetic anisotropy (PMA) of ultrathin Co films, ex situ Brillouin light scattering measurements were performed for various overlayer materials. The samples were prepared by molecular beam epitaxy and Cu, Al, and Au were used as overlayer materials. We observed a decrease in PMA of the Co with the Cu and Al overlayers. In addition, we found an unexpected result that the PMA is significantly reduced when an Au overlayer of 35 Å is covered by an extra Al capping layer. The amount of this reduction depends on the thickness of the Al layer. Our results lead us to speculate that misfit strain at the interface between the Al and the Au can be propagated through the Au layer to affect the magnetic properties of Co.

  3. Overlayer effects on perpendicular magnetic anisotropy in Co/Au/Cu films

    NASA Astrophysics Data System (ADS)

    Lee, Sukmock; Park, Sungkyun; Falco, Charles M.

    2001-03-01

    We have performed Brillouin light scattering measurements to investigate the effect on the perpendicular magnetic anisotropy (PMA) of overlayers on ultra--thin Co films prepared by Molecular Beam Epitaxy. The overlayer materials used for these studies were Al and Au. We observed a systematic decrease in PMA when using Al instead of Au overlayers, and will present results of the uniaxial anisotropies of the films as a function of Au underlayer thickness. In addition, we found the unexpected result that the PMA is significantly reduced when an Au overlayer of 3.5 nm is covered by an extra Al capping layer. The amount of this reduction depends on the thickness of the Al layer. We speculate that misfit strain at the interface between the Al and the Au can be propagated through the Au layer to affect the magnetic properties of Co.

  4. How to minimize CD variation and overlay degradation induced by film stress

    NASA Astrophysics Data System (ADS)

    Jung, Woo-Yung; Lim, Yong-Hyun; Park, Shin-Ae; Ahn, Sang-Joon; Lee, Ji-Hyun; Yoo, Jung-A.; Pyi, Seung-Ho; Kim, Jin-Woong

    2012-03-01

    It is getting harder to minimize feature size to satisfy bit growth requirement. 3D NAND flash memory has been developed to meet bit growth requirement without shrinking feature size. To increase the number of memory cells per unit area without shrinking feature size, we should increase the number of stacked film layers which finally become memory cells. Wafer warpage is induced by the stress between film and wafer. Both of film stress and wafer warpage increase in proportion to stacked film layers, and the increase of wafer warpage makes CD uniformity worse. Overlay degradation has no relation with wafer warpage, but has indirect relation with film stress. Wafer deformation in film deposition chamber is the source of overlay degradation. In this paper, we study the reasons why CD uniformity and overlay accuracy are affected by film stress, and suggest the methods which keep CD uniformity and overlay accuracy safe without additional processes.

  5. Use of recycled chunk rubber asphalt concrete (CRAC) on low volume roads and use of recycled crumb rubber modifier in asphalt pavements. Final report, June 1993-June 1995

    SciTech Connect

    Hossain, M.; Funk, L.P.; Sadeq, M.A.; Marucci, G.

    1995-06-01

    The major objective of this project was to formulate a Chunk Rubber Asphalt Concrete (CRAC) mix for use on low volume roads. CRAC is a rubber modified asphalt concrete product produced by the `dry process` where rubber chunks of 1/2 inch size are used as aggregate in a cold mix with a type C fly ash. The second objective of this project was to develop guidelines concerning the use of rubber modified asphalt concrete hot mix to include: (1) Design methods for use of asphalt-rubber mix for new construction and overlay, (2) Mix design method for asphalt-rubber, and (3) Test method for determining the amount of rubber in an asphalt-rubber concrete for quality control purposes.

  6. Integrated scatterometry for tight overlay and CD control to enable 20-nm node wafer manufacturing.

    NASA Astrophysics Data System (ADS)

    Benschop, Jos; Engelen, Andre; Cramer, Hugo; Kubis, Michael; Hinnen, Paul; van der Laan, Hans; Bhattacharyya, Kaustuve; Mulkens, Jan

    2013-04-01

    The overlay, CDU and focus requirements for the 20nm node can only be met using a holistic lithography approach whereby full use is made of high-order, field-by-field, scanner correction capabilities. An essential element in this approach is a fast, precise and accurate in-line metrology sensor, capable to measure on product. The capabilities of the metrology sensor as well as the impact on overlay, CD and focus will be shared in this paper.

  7. Application of overlay modeling and control with Zernike polynomials in an HVM environment

    NASA Astrophysics Data System (ADS)

    Ju, JaeWuk; Kim, MinGyu; Lee, JuHan; Nabeth, Jeremy; Jeon, Sanghuck; Heo, Hoyoung; Robinson, John C.; Pierson, Bill

    2016-03-01

    Shrinking technology nodes and smaller process margins require improved photolithography overlay control. Generally, overlay measurement results are modeled with Cartesian polynomial functions for both intra-field and inter-field models and the model coefficients are sent to an advanced process control (APC) system operating in an XY Cartesian basis. Dampened overlay corrections, typically via exponentially or linearly weighted moving average in time, are then retrieved from the APC system to apply on the scanner in XY Cartesian form for subsequent lot exposure. The goal of the above method is to process lots with corrections that target the least possible overlay misregistration in steady state as well as in change point situations. In this study, we model overlay errors on product using Zernike polynomials with same fitting capability as the process of reference (POR) to represent the wafer-level terms, and use the standard Cartesian polynomials to represent the field-level terms. APC calculations for wafer-level correction are performed in Zernike basis while field-level calculations use standard XY Cartesian basis. Finally, weighted wafer-level correction terms are converted to XY Cartesian space in order to be applied on the scanner, along with field-level corrections, for future wafer exposures. Since Zernike polynomials have the property of being orthogonal in the unit disk we are able to reduce the amount of collinearity between terms and improve overlay stability. Our real time Zernike modeling and feedback evaluation was performed on a 20-lot dataset in a high volume manufacturing (HVM) environment. The measured on-product results were compared to POR and showed a 7% reduction in overlay variation including a 22% terms variation. This led to an on-product raw overlay Mean + 3Sigma X&Y improvement of 5% and resulted in 0.1% yield improvement.

  8. An overlay gel method for identification and isolation of bacterial beta-lactamases.

    PubMed

    Eftekhar, Fereshteh; Rafiee, Roya

    2006-01-01

    A modification of the iodometric technique using an overlay gel was employed for fast identification and isolation of beta-lactamase types TEM, SHV and AmpC from non-denaturing gels. Osmotic shock preparations of the three beta-lactamases were run on polyacrylamide gels without SDS and ampicillin containing overlay gels were flooded with the iodine solution before being placed on polyacrylamide gel strips. Distinct clear bands appeared in dark blue backgrounds indicating beta-lactamase activity.

  9. Development of polymer concrete for dike insulation at LNG (liquified natural gas) facilities: Phase 3, Final report, November 1, 1986-August 31, 1987

    SciTech Connect

    Fontana, J.J.; Reams, W.; Elling, D.

    1987-10-31

    Insulating polymer concrete (IPC) composites have been developed for use as a dike insulation material at Liquefied Natural Gas (LNG) storage facilities. Using inert, low density multicellular glass and/or ceramic macrospheres with unsaturated polyester or epoxy resins, a lightweight insulating polymer concrete has been made. Installation of IPC as an overlay on a concrete substrate has been shown to be a practical method of insulating LNG storage tank containment dikes. In many cases, the impounding dikes have compacted earthen or crushed stone surfaces. In these cases, the cost and time required to install a concrete substrate could be eliminated if the IPC can be installed by spraying or shotcretting it directly on the earthen or crushed stone surfaces. An evaluation was made of shotcretting IPC directly onto earthen and crushed stone surfaces using a polymer shotcrete machine. Shotcrete installations were made on sloped and vertical surfaces. In all cases, machine application was made without technical difficulty. Polymer shotcrete technology was shown to be technically feasible for IPC applications to a variety of substrates and surface geometries. Cost estimates indicate that IPC shotcrete applications can be almost 30% less than the installation of a concrete substrate with an IPC overlay.

  10. Fiber reinforced concrete solar collector

    SciTech Connect

    Slemmons, A. J.; Newgard, P. J.

    1985-05-07

    A solar collector is disclosed comprising a glass member having a solar selective coating thereon, and a molded, glass-reinforced concrete member bonded to the glass member and shaped to provide a series of passageways between the glass member and the fiber-reinforced concrete member capable of carrying heat exchanging fluid therethrough. The fiber-reinforced concrete member may be formed by spraying a thin layer of concrete and chopped fibers such as chopped glass fibers onto a mold to provide an inexpensive and lightweight, thin-walled member. The fiber-reinforced concrete member may have a lightweight cellular concrete backing thereon for insulation purposes. The collector is further characterized by the use of materials which have substantially matching thermal coefficients of expansion over the temperature range normally encountered in the use of solar collectors.

  11. Chlorine signal attenuation in concrete.

    PubMed

    Naqvi, A A; Maslehuddin, M; ur-Rehman, Khateeb; Al-Amoudi, O S B

    2015-11-01

    The intensity of prompt gamma-ray was measured at various depths from chlorine-contaminated silica fume (SF) concrete slab concrete specimens using portable neutron generator-based prompt gamma-ray setup. The intensity of 6.11MeV chloride gamma-rays was measured from the chloride contaminated slab at distance of 15.25, 20.25, 25.25, 30.25 and 35.25cm from neutron target in a SF cement concrete slab specimens. Due to attenuation of thermal neutron flux and emitted gamma-ray intensity in SF cement concrete at various depths, the measured intensity of chlorine gamma-rays decreases non-linearly with increasing depth in concrete. A good agreement was noted between the experimental results and the results of Monte Carlo simulation. This study has provided useful experimental data for evaluating the chloride contamination in the SF concrete utilizing gamma-ray attenuation method.

  12. Application Oriented Flow Routing Algorithm for VoIP Overlay Networks

    NASA Astrophysics Data System (ADS)

    Wipusitwarakun, Komwut; Chimmanee, Sanon

    Overlay networks which are dynamically created over underlying IP networks are becoming widely used for delivering multimedia contents since they can provide several additional user-definable services. Multiple overlay paths between a source-destination overlay node pair are designed to improve service robustness against failures and bandwidth fluctuation of the underlying networks. Multimedia traffic can be distributed over those multiple paths in order to maximize paths' utilization and to increase application throughputs. Most of flow-based routing algorithms consider only common metrics such as paths' bandwidth or delay, which may be effective for data applications but not for real-time applications such as Voice over IP (VoIP), in which different levels of such performance metrics may give the same level of the performance experienced by end users. This paper focuses on such VoIP overlay networks and proposes a novel alternative path based flow routing algorithm using an application-specific traffic metric, i.e. “VoIP Path Capacity (VPCap), ” to calculate the maximum number of QoS satisfied VoIP flows which may be distributed over each available overlay path at a moment. The simulation results proved that more QoS-satisfied VoIP sessions can be established over the same multiple overlay paths, comparing to traditional approaches.

  13. VMCast: A VM-Assisted Stability Enhancing Solution for Tree-Based Overlay Multicast

    PubMed Central

    Gu, Weidong; Zhang, Xinchang; Gong, Bin; Zhang, Wei; Wang, Lu

    2015-01-01

    Tree-based overlay multicast is an effective group communication method for media streaming applications. However, a group member’s departure causes all of its descendants to be disconnected from the multicast tree for some time, which results in poor performance. The above problem is difficult to be addressed because overlay multicast tree is intrinsically instable. In this paper, we proposed a novel stability enhancing solution, VMCast, for tree-based overlay multicast. This solution uses two types of on-demand cloud virtual machines (VMs), i.e., multicast VMs (MVMs) and compensation VMs (CVMs). MVMs are used to disseminate the multicast data, whereas CVMs are used to offer streaming compensation. The used VMs in the same cloud datacenter constitute a VM cluster. Each VM cluster is responsible for a service domain (VMSD), and each group member belongs to a specific VMSD. The data source delivers the multicast data to MVMs through a reliable path, and MVMs further disseminate the data to group members along domain overlay multicast trees. The above approach structurally improves the stability of the overlay multicast tree. We further utilized CVM-based streaming compensation to enhance the stability of the data distribution in the VMSDs. VMCast can be used as an extension to existing tree-based overlay multicast solutions, to provide better services for media streaming applications. We applied VMCast to two application instances (i.e., HMTP and HCcast). The results show that it can obviously enhance the stability of the data distribution. PMID:26562152

  14. Optimization of reinforced concrete slabs

    NASA Technical Reports Server (NTRS)

    Ferritto, J. M.

    1979-01-01

    Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

  15. Fire Resistance of Geopolymer Concretes

    DTIC Science & Technology

    2010-03-21

    1 Project report – Grant FA23860814096, "Fire resistance of geopolymer concretes" – J. Provis, University of Melbourne 1. Background and...experimental program This project provided funding for us to carry out fire testing of geopolymer concrete specimens and associated laboratory...testing. The focus of this report will be the outcomes of the series of pilot-scale (4’×4’×6”) tests on geopolymer concrete panels, which were conducted

  16. Concrete Mixing Methods and Concrete Mixers: State of the Art

    PubMed Central

    Ferraris, Chiara F.

    2001-01-01

    As for all materials, the performance of concrete is determined by its microstructure. Its microstructure is determined by its composition, its curing conditions, and also by the mixing method and mixer conditions used to process the concrete. This paper gives an overview of the various types of mixing methods and concrete mixers commercially available used by the concrete industry. There are two main types of mixers used: batch mixers and continuous mixers. Batch mixers are the most common. To determine the mixing method best suited for a specific application, factors to be considered include: location of the construction site (distance from the batching plant), the amount of concrete needed, the construction schedule (volume of concrete needed per hour), and the cost. Ultimately, the quality of the concrete produced determines its performance after placement. An important measure of the quality is the homogeneity of the material after mixing. This paper will review mixing methods in regards to the quality of the concrete produced. Some procedures used to determine the effectiveness of the mixing will be examined. PMID:27500029

  17. Focus, edge detection, and CCD camera characterization for development of an optical overlay calibration standard

    NASA Astrophysics Data System (ADS)

    Fox, Stephen Harris

    2000-11-01

    In order to ensure continued growth and development, a consortium of IC manufacturers has produced a ``roadmap'' of critical technologies immediately needed, and predicted to be needed, by the industry in the near future. Reduction of critical dimensions (the smallest dimensions of an IC, typically the CMOS gate length) necessitate tighter control over the alignment of one mask (i.e., lithographic) level relative to another. Measurement of the relative alignment of two such masks is known as ``overlay metrology.'' Reference standards for calibration of present and planned overlay metrology tools must be developed for the IC industry to meet their anticipated needs. This work contributes to the development of calibration standards and methods for overlay metrology by consideration and characterization of several aspects of overlay measurement that introduce error into the measurement. Unavoidable variations in the focus response of an overlay tool lead to errors due to coupling of lateral motion of the measuring microscope with its focus motion, and its variation of optical aberrations with focus. We consider various algorithms available for autofocus of an optical microscope. The algorithms have been tested with simulated and real data. We have found that an algorithm's response depends crucially on the material system being investigated. We also determined an optimal algorithm of those tested for use on the NIST optical overlay metrology tool. Detection of feature edges and their positions on the IC are critical to overlay metrology. We investigated various algorithms for edge detection appropriate for the optical overlay metrology tool at the National Institute of Standards and Technology (NIST). Results comparing the performance of the recommended algorithm against various algorithms used in the industry are presented. Length standards are normally calibrated with a scanning photometric stage monitored by laser interferometry. Optical overlay patterns are

  18. Corrosion control of steel-reinforced concrete

    NASA Astrophysics Data System (ADS)

    Chung, D. D. L.

    2000-10-01

    The methods and materials for corrosion control of steel-reinforced concrete are reviewed. The methods are steel surface treatment, the use of admixtures in concrete, surface coating on concrete, and cathodic protection.

  19. Evaluation of Tizian overlays by means of a swept source optical coherence tomography system

    NASA Astrophysics Data System (ADS)

    Marcauteanu, Corina; Sinescu, Cosmin; Negrutiu, Meda Lavinia; Stoica, Eniko Tunde; Topala, Florin; Duma, Virgil Florin; Bradu, Adrian; Podoleanu, Adrian Gh.

    2016-03-01

    The teeth affected by pathologic attrition can be restored by a minimally invasive approach, using Tizian overlays. In this study we prove the advantages of a fast swept source (SS) OCT system in the evaluation of Tizian overlays placed in an environment characterized by high occlusal forces. 12 maxillary first premolars were extracted and prepared for overlays. The Tizian overlays were subjected to 3000 alternating cycles of thermo-cycling (from -10°C to +50°C) and to mechanical occlusal overloads (at 800 N). A fast SS OCT system was used to evaluate the Tizian overlays before and after the mechanical and thermal straining. The SS (Axsun Technologies, Billerica, MA) has a central wavelength of 1060 nm, sweeping range of 106 nm (quoted at 10 dB) and a 100 kHz line rate. The depth resolution of the system, measured experimentally in air was 10 μm. The imaging system used for this study offers high spatial resolutions in both directions, transversal and longitudinal of around 10 μm, a high sensitivity, and it is also able to acquire entire tridimensional (3D)/volume reconstructions as fast as 2.5 s. Once the full dataset was acquired, rendered high resolutions en-face projections could be produced. Using them, the overlay (i.e., cement) abutment tooth interfaces were remarked both on B-scans/two-dimensional (2D) sections and in the 3D reconstructions. Using the system several open interfaces were possible to detect. The fast SS OCT system thus proves useful in the evaluation of zirconia reinforced composite overlays, placed in an environment characterized by high occlusal forces.

  20. Characterization and mitigation of overlay error on silicon wafers with nonuniform stress

    NASA Astrophysics Data System (ADS)

    Brunner, T.; Menon, V.; Wong, C.; Felix, N.; Pike, M.; Gluschenkov, O.; Belyansky, M.; Vukkadala, P.; Veeraraghavan, S.; Klein, S.; Hoo, C. H.; Sinha, J.

    2014-03-01

    Process-induced overlay errors are a growing problem in meeting the ever-tightening overlay requirements for integrated circuit production. While uniform process-induced stress is easily corrected, non-uniform stress across the wafer is much more problematic, often resulting in non-correctable overlay errors. Measurements of the wafer geometry of free, unchucked wafers give a powerful method for characterization of such non-uniform stress. We will describe a Patterned Wafer Geometry (PWG) tool, which uses optical methods to measure the geometry of in-process wafers. PWG data can be related to In-Plane Distortion (IPD) of the wafer through the PIR (Predicted IPD Residual) metric. This paper will explore the relationship between the PIR data and measured overlay data on Engineered Stress Monitor (ESM) wafers containing various designed stress variations. The process used to fabricate ESM wafers is quite versatile and can mimic many different stress variation signatures. For this study, ESM wafers were built with strong across-wafer stress variation and another ESM wafer set was built with strong intrafield stress variation. IPD was extensively characterized in two different ways: using standard overlay error metrology and using PWG metrology. Strong correlation is observed between these two independent sets of data, indicating that the PIR metric is able to clearly see wafer distortions. We have taken another step forward by using PIR data from the PWG tool to correct process-induced overlay error by feedforward to the exposure tool, a novel method that we call PWG-FF. We conclude that appropriate wafer geometry measurements of in-process wafers have strong potential to characterize and reduce process-induced overlay errors.

  1. Simultaneous overlay and CD measurement for double patterning: scatterometry and RCWA approach

    NASA Astrophysics Data System (ADS)

    Li, Jie; Liu, Zhuan; Rabello, Silvio; Dasari, Prasad; Kritsun, Oleg; Volkman, Catherine; Park, Jungchul; Singh, Lovejeet

    2009-03-01

    As optical lithography advances to 32 nm technology node and beyond, double patterning technology (DPT) has emerged as an attractive solution to circumvent the fundamental optical limitations. DPT poses unique demands on critical dimension (CD) uniformity and overlay control, making the tolerance decrease much faster than the rate at which critical dimension shrinks. This, in turn, makes metrology even more challenging. In the past, multi-pad diffractionbased overlay (DBO) using empirical approach has been shown to be an effective approach to measure overlay error associated with double patterning [1]. In this method, registration errors for double patterning were extracted from specially designed diffraction targets (three or four pads for each direction); CD variation is assumed negligible within each group of adjacent pads and not addressed in the measurement. In another paper, encouraging results were reported with a first attempt at simultaneously extracting overlay and CD parameters using scatterometry [2]. In this work, we apply scatterometry with a rigorous coupled wave analysis (RCWA) approach to characterize two double-patterning processes: litho-etch-litho-etch (LELE) and litho-freeze-litho-etch (LFLE). The advantage of performing rigorous modeling is to reduce the number of pads within each measurement target, thus reducing space requirement and improving throughput, and simultaneously extract CD and overlay information. This method measures overlay errors and CDs by fitting the optical signals with spectra calculated from a model of the targets. Good correlation is obtained between the results from this method and that of several reference techniques, including empirical multi-pad DBO, CD-SEM, and IBO. We also perform total measurement uncertainty (TMU) analysis to evaluate the overall performance. We demonstrate that scatterometry provides a promising solution to meet the challenging overlay metrology requirement in DPT.

  2. Using the overlay assay to qualitatively measure bacterial production of and sensitivity to pneumococcal bacteriocins.

    PubMed

    Maricic, Natalie; Dawid, Suzanne

    2014-09-30

    Streptococcus pneumoniae colonizes the highly diverse polymicrobial community of the nasopharynx where it must compete with resident organisms. We have shown that bacterially produced antimicrobial peptides (bacteriocins) dictate the outcome of these competitive interactions. All fully-sequenced pneumococcal strains harbor a bacteriocin-like peptide (blp) locus. The blp locus encodes for a range of diverse bacteriocins and all of the highly conserved components needed for their regulation, processing, and secretion. The diversity of the bacteriocins found in the bacteriocin immunity region (BIR) of the locus is a major contributor of pneumococcal competition. Along with the bacteriocins, immunity genes are found in the BIR and are needed to protect the producer cell from the effects of its own bacteriocin. The overlay assay is a quick method for examining a large number of strains for competitive interactions mediated by bacteriocins. The overlay assay also allows for the characterization of bacteriocin-specific immunity, and detection of secreted quorum sensing peptides. The assay is performed by pre-inoculating an agar plate with a strain to be tested for bacteriocin production followed by application of a soft agar overlay containing a strain to be tested for bacteriocin sensitivity. A zone of clearance surrounding the stab indicates that the overlay strain is sensitive to the bacteriocins produced by the pre-inoculated strain. If no zone of clearance is observed, either the overlay strain is immune to the bacteriocins being produced or the pre-inoculated strain does not produce bacteriocins. To determine if the blp locus is functional in a given strain, the overlay assay can be adapted to evaluate for peptide pheromone secretion by the pre-inoculated strain. In this case, a series of four lacZ-reporter strains with different pheromone specificity are used in the overlay.

  3. Concrete Operations and Attentional Capacity.

    ERIC Educational Resources Information Center

    Chapman, Michael; Lindenberger, Ulman

    1989-01-01

    To test predictions regarding the attentional capacity requirements of Piaget's stage of concrete operations, a battery of concrete operational tasks and two measures of attentional capacity were administered to 120 first-, second-, and third-graders. Findings concern class inclusion, transitivity of length and weight, and multiplication of…

  4. 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…

  5. Molded Concrete Center Mine Wall

    NASA Technical Reports Server (NTRS)

    Lewis, E. V.

    1987-01-01

    Proposed semiautomatic system forms concrete-foam wall along middle of coal-mine passage. Wall helps support roof and divides passage into two conduits needed for ventilation of coal face. Mobile mold and concrete-foam generator form sections of wall in place.

  6. Technology Solutions Case Study: Insulating Concrete Forms

    SciTech Connect

    none,

    2012-10-01

    This Pacific Northwest National Laboratory project investigated insulating concrete forms—rigid foam, hollow walls that are filled with concrete for highly insulated, hurricane-resistant construction.

  7. Nuclear Power Plant Concrete Structures

    SciTech Connect

    Basu, Prabir; Labbe, Pierre; Naus, Dan

    2013-01-01

    A nuclear power plant (NPP) involves complex engineering structures that are significant items of the structures, systems and components (SSC) important to the safe and reliable operation of the NPP. Concrete is the commonly used civil engineering construction material in the nuclear industry because of a number of advantageous properties. The NPP concrete structures underwent a great degree of evolution, since the commissioning of first NPP in early 1960. The increasing concern with time related to safety of the public and environment, and degradation of concrete structures due to ageing related phenomena are the driving forces for such evolution. The concrete technology underwent rapid development with the advent of chemical admixtures of plasticizer/super plasticizer category as well as viscosity modifiers and mineral admixtures like fly ash and silica fume. Application of high performance concrete (HPC) developed with chemical and mineral admixtures has been witnessed in the construction of NPP structures. Along with the beneficial effect, the use of admixtures in concrete has posed a number of challenges as well in design and construction. This along with the prospect of continuing operation beyond design life, especially after 60 years, the impact of extreme natural events ( as in the case of Fukushima NPP accident) and human induced events (e.g. commercial aircraft crash like the event of September 11th 2001) has led to further development in the area of NPP concrete structures. The present paper aims at providing an account of evolution of NPP concrete structures in last two decades by summarizing the development in the areas of concrete technology, design methodology and construction techniques, maintenance and ageing management of concrete structures.

  8. A Markov Model for the EpiChord Peer-to-Peer Overlay in an XCAST Enabled Network

    DTIC Science & Technology

    2007-01-01

    overlay. Previous work showed that P2P networks benefit from the integration of the overlay network with the underlay network in which multi-destination...multicast routes between peers in different ISP networks . With larger P2P overlays, the use of host-group multicast in DHT creates too much traffic and...on Advanced Information Networking and Applications (AINA’04) Vol. 2, 2004. [9] T. Oh-ishi, K. Sakai, K. Kikuma, and A. Kurokawa, Study of the

  9. Infrared differential interference contrast microscopy for overlay metrology on 3D-interconnect bonded wafers

    NASA Astrophysics Data System (ADS)

    Ku, Yi-sha; Shyu, Deh-Ming; Lin, Yeou-Sung; Cho, Chia-Hung

    2013-04-01

    Overlay metrology for stacked layers will be playing a key role in bringing 3D IC devices into manufacturing. However, such bonded wafer pairs present a metrology challenge for optical microscopy tools by the opaque nature of silicon. Using infrared microscopy, silicon wafers become transparent to the near-infrared (NIR) wavelengths of the electromagnetic spectrum, enabling metrology at the interface of bonded wafer pairs. Wafers can be bonded face to face (F2F) or face to back (F2B) which the stacking direction is dictated by how the stacks are carried in the process and functionality required. For example, Memory stacks tend to use F2B stacking enables a better managed design. Current commercial tools use single image technique for F2F bonding overlay measurement because depth of focus is sufficient to include both surfaces; and use multiple image techniques for F2B overlay measurement application for the depth of focus is no longer sufficient to include both stacked wafer surfaces. There is a need to specify the Z coordinate or stacking wafer number through the silicon when visiting measurement wafer sites. Two shown images are of the same (X, Y) but separate Z location acquired at focus position of each wafer surface containing overlay marks. Usually the top surface image is bright and clear; however, the bottom surface image is somewhat darker and noisier as an adhesive layer is used in between to bond the silicon wafers. Thus the top and bottom surface images are further processed to achieve similar brightness and noise level before merged for overlay measurement. This paper presents a special overlay measurement technique, using the infrared differential interference contrast (DIC) microscopy technique to measure the F2B wafer bonding overlay by a single shot image. A pair of thinned wafers at 50 and 150 μm thickness is bonded on top of a carrier wafer to evaluate the bonding overlay. It works on the principle of interferometry to gain information about the

  10. Electronic structures of tungsten surfaces with barium overlayers by field emission and photofield emission

    NASA Astrophysics Data System (ADS)

    Ibrahim, Zahraa A. S. A.

    The total energy distributions (TEDs) in field emission (FE) and photofield emission (PFE) and the work functions have been measured at room temperature for the (100), (110) and (111) W facets with Ba overlayers in the range of coverage from 0 to 1 monolayer. In order to interpret the experimental data, the full-potential linear augmented plane wave method for calculating the electronic structures of periodic lattices within the LDA has been extended to obtain the TEDs in FE and PFE from W/vacuum and W/Ba/vacuum interfaces. A prominent peak observed experimentally at -1.90 eV in PFE from W(100) with a c(2x2) Ba overlayer is attributed, in contrast to previous work, to hybridization of dz2 -like surface states of clean W(100) with s -like states of the overlayer. It is suggested that a prominent asymmetrical peak observed at -0.65 eV in FE from W(111) is due to two bands of dz 2 -like surface resonances, and a prominent peak observed at about -2.0 eV in PFE from W(111) with a (1x1) Ba overlayer is attributed to hybridization of these same resonances with s -like states of the overlayer. It is shown that several of the peaks observed in PFE are induced by the reduced symmetry of the overlayer. It is found that when an isolated (31/2x3 1/2) Ba layer is adsorbed on W(111) it undergoes a nonmetal-to-metal transition and the surface electronic structure is dominated by inter-layer W-Ba interactions. The atomically-denser isolated (1x1) Ba layer is metallic, and when it is adsorbed on W(111) the surface electronic structure is dominated by intra-layer Ba-Ba interactions. These properties are also discussed for Ba overlayers on W(100) and W(110). A c(2x2) Ba overlayer on W(100) induces a strong electric dipole layer between the substrate and the overlayer and a weak oppositely-directed dipole layer outside the surface, which together account quantitatively for the observed reduction in work function. In view of the success of the present method in interpreting the TEDs in

  11. Implementation and benefits of advanced process control for lithography CD and overlay

    NASA Astrophysics Data System (ADS)

    Zavyalova, Lena; Fu, Chong-Cheng; Seligman, Gary S.; Tapp, Perry A.; Pol, Victor

    2003-05-01

    Due to the rapidly reduced imaging process windows and increasingly stingent device overlay requirements, sub-130 nm lithography processes are more severely impacted than ever by systamic fault. Limits on critical dimensions (CD) and overlay capability further challenge the operational effectiveness of a mix-and-match environment using multiple lithography tools, as such mode additionally consumes the available error budgets. Therefore, a focus on advanced process control (APC) methodologies is key to gaining control in the lithographic modules for critical device levels, which in turn translates to accelerated yield learning, achieving time-to-market lead, and ultimately a higher return on investment. This paper describes the implementation and unique challenges of a closed-loop CD and overlay control solution in high voume manufacturing of leading edge devices. A particular emphasis has been placed on developing a flexible APC application capable of managing a wide range of control aspects such as process and tool drifts, single and multiple lot excursions, referential overlay control, 'special lot' handling, advanced model hierarchy, and automatic model seeding. Specific integration cases, including the multiple-reticle complementary phase shift lithography process, are discussed. A continuous improvement in the overlay and CD Cpk performance as well as the rework rate has been observed through the implementation of this system, and the results are studied.

  12. Compensation of overlay errors due to mask bending and non-flatness for EUV masks

    NASA Astrophysics Data System (ADS)

    Chandhok, Manish; Goyal, Sanjay; Carson, Steven; Park, Seh-Jin; Zhang, Guojing; Myers, Alan M.; Leeson, Michael L.; Kamna, Marilyn; Martinez, Fabian C.; Stivers, Alan R.; Lorusso, Gian F.; Hermans, Jan; Hendrickx, Eric; Govindjee, Sanjay; Brandstetter, Gerd; Laursen, Tod

    2009-03-01

    EUV blank non-flatness results in both out of plane distortion (OPD) and in-plane distortion (IPD) [3-5]. Even for extremely flat masks (~50 nm peak to valley (PV)), the overlay error is estimated to be greater than the allocation in the overlay budget. In addition, due to multilayer and other thin film induced stresses, EUV masks have severe bow (~1 um PV). Since there is no electrostatic chuck to flatten the mask during the e-beam write step, EUV masks are written in a bent state that can result in ~15 nm of overlay error. In this article we present the use of physically-based models of mask bending and non-flatness induced overlay errors, to compensate for pattern placement of EUV masks during the e-beam write step in a process we refer to as E-beam Writer based Overlay error Correction (EWOC). This work could result in less restrictive tolerances for the mask blank non-flatness specs which in turn would result in less blank defects.

  13. Overlay control methodology comparison: field-by-field and high-order methods

    NASA Astrophysics Data System (ADS)

    Huang, Chun-Yen; Chiu, Chui-Fu; Wu, Wen-Bin; Shih, Chiang-Lin; Huang, Chin-Chou Kevin; Huang, Healthy; Choi, DongSub; Pierson, Bill; Robinson, John C.

    2012-03-01

    Overlay control in advanced integrated circuit (IC) manufacturing is becoming one of the leading lithographic challenges in the 3x and 2x nm process nodes. Production overlay control can no longer meet the stringent emerging requirements based on linear composite wafer and field models with sampling of 10 to 20 fields and 4 to 5 sites per field, which was the industry standard for many years. Methods that have emerged include overlay metrology in many or all fields, including the high order field model method called high order control (HOC), and field by field control (FxFc) methods also called correction per exposure. The HOC and FxFc methods were initially introduced as relatively infrequent scanner qualification activities meant to supplement linear production schemes. More recently, however, it is clear that production control is also requiring intense sampling, similar high order and FxFc methods. The added control benefits of high order and FxFc overlay methods need to be balanced with the increased metrology requirements, however, without putting material at risk. Of critical importance is the proper control of edge fields, which requires intensive sampling in order to minimize signatures. In this study we compare various methods of overlay control including the performance levels that can be achieved.

  14. Impact of CD and overlay errors on double-patterning processes

    NASA Astrophysics Data System (ADS)

    Lapeyre, Céline; Barnola, Sébastien; Servin, Isabelle; Gaugirana, Stéphanie; Salvetat, Vincent; Magome, Nobutaka; Hazelton, Andrew J.; McCallum, Martin

    2009-03-01

    Double patterning (DP) is today the main solution to extend immersion lithography to the 32 nm node and beyond. Pitch splitting process with hardmask transfer and spacer process have been developed at CEA-LETI-Minatec. This paper focuses on experimental data using dry ArF lithography with a k1 factor of 0.20 ; the relative impact of each DP step on overlay and CD uniformity budgets is analyzed. In addition, topography issues related to the presence of the patterned hard mask layer during the second imaging step is also investigated. Tool-to-itself overlay, image placement on the reticle and wafer deformation induced by this DP process are evaluated experimentally and resulting errors on CD budget have been determined. CD uniformity error model developed by Nikon describing the relationship between CD and overlay in different DP processes is validated experimentally.

  15. Weld overlay coatings for erosion control. Task A: Literature review, progress report

    SciTech Connect

    Levin, B.; DuPont, J.N.; Marder, A.R.

    1993-03-03

    A literature review was made. In spite of similarities between abrasive wear and solid particle erosion, weld overlay hardfacing alloys that exhibit high abrasion resistance may not necessarily have good erosion resistance. The performance of weld overlay hardfacing alloys in erosive environments has not been studied in detail. It is believed that primary-solidified hard phases such as carbides and intermetallic compounds have a strong influence on erosion resistance of weld overlay hardfacing alloys. However, relationships between size, shape, and volume fraction of hard phases in a hardfacing alloys and erosion resistance were not established. Almost all hardfacing alloys can be separated into two major groups based upon chemical compositions of the primary solidified hard phases: (a) carbide hardening alloys (Co-base/carbide, WC-Co and some Fe base superalloys); and (b) intermetallic hardening alloys (Ni-base alloys, austenitic steels, iron-aluminides).

  16. Laser-induced desorption of overlayer films off a heated metal substrate

    NASA Astrophysics Data System (ADS)

    Gu, Xiang; Urbassek, Herbert M.

    2007-02-01

    The temperature-induced desorption of adsorbed overlayer films with thicknesses between 4 and 200 ML off a suddenly heated metal substrate is studied using molecular-dynamics simulation. We observe that the rapid heating vaporizes the surface-near part of the overlayer film. The initial heating-induced thermoelastic pressure and the vapor pressure in the vapor film drive the remaining film as a large relatively cold cluster away from the surface. In our simulations, the material present in the developing vapor film amounts to roughly 2 ML and is quite independent of the overlayer film thickness. For cluster thicknesses beyond 40 ML, the desorption time increases only little with film thickness, while the resulting cluster velocity decreases only slightly.

  17. Characterizing the Global Impact of P2P Overlays on the AS-Level Underlay

    NASA Astrophysics Data System (ADS)

    Rasti, Amir Hassan; Rejaie, Reza; Willinger, Walter

    This paper examines the problem of characterizing and assessing the global impact of the load imposed by a Peer-to-Peer (P2P) overlay on the AS-level underlay. In particular, we capture Gnutella snapshots for four consecutive years, obtain the corresponding AS-level topology snapshots of the Internet and infer the AS-paths associated with each overlay connection. Assuming a simple model of overlay traffic, we analyze the observed load imposed by these Gnutella snapshots on the AS-level underlay using metrics that characterize the load seen on individual AS-paths and by the transit ASes, illustrate the churn among the top transit ASes during this 4-year period, and describe the propagation of traffic within the AS-level hierarchy.

  18. Effects of indium and tin overlayers on the photoluminescence spectrum of mercuric iodide

    SciTech Connect

    James, R.B. ); Bao, X.J.; Schlesinger, T.E. ); Ortale, C.; Cheng, A.Y. )

    1990-03-01

    Mercuric iodide (HgI{sub 2} ) crystals with semitransparent metal overlayers of indium and tin were characterized using low-temperature photoluminescence (PL) spectroscopy. The PL spectra were found to differ for points beneath the thin metal overlayers and points that were masked off during each deposition. The photoluminescence data were compared with PL measurements taken on HgI{sub 2} photodetectors with indium-tin-oxide (ITO) entrance electrodes. The similarities of the spectra for the HgI{sub 2} samples with In, Sn, and ITO conducting overlayers indicate that the regions in the ITO-contacted photodetectors with relatively poor photoresponses are associated with the interaction of indium or tin with the mercuric iodide substrate.

  19. Rapid Testing of Fresh Concrete

    DTIC Science & Technology

    1975-05-01

    Cementforenlng, Oslo, 1952). 1.1 Orchard, 0. F., "The Effect of the Vacum Process on Concrete Mix Design ," Symposiwn on Mix Design and Qualify Control...ASTM, Vol 33, Part I (1933), pp 297-307. Orchard, D. F., "The Effect of the Vacuum Process on Concrete Mix Design ," Symposium on Mix Design and... Designed for Use in Determining Constituents of Fresh Concrete," Public floads, Vol 13, No. 9 (1932), p 151. 9 Cook, G. C, "Effect of Time of Haul

  20. Concrete Construction Using Slipform Techniques.

    DTIC Science & Technology

    1982-11-01

    Operations 75 4.1.3 Ramp, Curb, Gutter, Sidewalk and Median Paving "/ 4.1.4 Canal Lining 80 4.2 Cast-in-Place Pipe 82 4.3 Tunnel Inverts 83 4.4...101 APPENDIX B - Bibliography 102 b. -E CHAPTER 1 INTRODUCTION 1.1 BACKGROUND The formwork for concrete structures represents a critical part of...concrete construction, in terms of cost and importance toward getting the job done properly and on time. In fact, concrete formwork frequently costs more

  1. A safety evaluation for overlay disbonding of high-temperature and pressure vessels

    SciTech Connect

    Horita, Ryuichi; Nakajima; Hiroyuki; Tanaka, Kazunori; Murakami, Shunzo; Fujii, Tadaomi

    1995-11-01

    Hydrogen induced disbonding test (autoclave test) of stainless weld-overlaid 2-1/4Cr-1Mo and 2-1/4Cr-1Mo-1/4V steel, and the calculations of residual hydrogen contents at the fusion boundary in the specimens and actual vessels, were performed. The effects of microstructure of weld overlay near the fusion boundary and postweld heat treatment on disbonding resistance were clarified, and critical hydrogen content values in weld overlay to prevent disbonding were obtained. A simple evaluation method for disbonding in actual vessels using Tempering Parameter was established.

  2. Metrology target design simulations for accurate and robust scatterometry overlay measurements

    NASA Astrophysics Data System (ADS)

    Ben-Dov, Guy; Tarshish-Shapir, Inna; Gready, David; Ghinovker, Mark; Adel, Mike; Herzel, Eitan; Oh, Soonho; Choi, DongSub; Han, Sang Hyun; El Kodadi, Mohamed; Hwang, Chan; Lee, Jeongjin; Lee, Seung Yoon; Lee, Kuntack

    2016-03-01

    Overlay metrology target design is an essential step prior to performing overlay measurements. This step is done through the optimization of target parameters for a given process stack. A simulation tool is therefore used to improve measurement performances. This work shows how our Metrology Target Design (MTD) simulator helps significantly in the target design process. We show the role of film and Optical CD measurements in improving significantly the fidelity of the simulations. We demonstrate that for various target design parameters we are capable of predicting measured performance metrics by simulations and correctly rank various designs performances.

  3. Robotic weld overlay coatings for erosion control. Quarterly technical progress report, January 1993--March 1993

    SciTech Connect

    Levin, B.F.; Dupont, J.N.; Marder, A.R.

    1993-04-18

    Twelve weld overlay hardfacing alloys have been selected for preliminary erosion testing based on a literature review These alloys have been separated into three major groups: (1) Cobalt containing alloys, (2) Nickel-base alloys, (3) Iron base alloys. These alloys are being applied to carbon steel substrates and will undergo preliminary erosion testing to identify candidates weld overlay alloys for erosion control in CFB boilers. The candidate alloys selected from the preliminary erosion tests will then undergo more detailed evaluations in future research.

  4. An Integrated Dynamic Online Management Framework for QoS-Sensitive Multimedia Overlay Networks

    NASA Astrophysics Data System (ADS)

    Kim, Sungwook; Choi, Myungwhan; Kim, Sungchun

    New multimedia services over cellular/WLAN overlay networks require different Quality of Service (QoS) levels. Therefore, an efficient network management system is necessary in order to realize QoS sensitive multimedia services while enhancing network performance. In this paper, we propose a new online network management framework for overlay networks. Our online approach to network management exhibits dynamic adaptability, flexibility, and responsiveness to the traffic conditions in multimedia networks. Simulation results indicate that our proposed framework can strike the appropriate balance between performance criteria under widely varying diverse traffic loads.

  5. A Spatial Overlay Ranking Method for a Geospatial Search of Text Objects

    USGS Publications Warehouse

    Lanfear, Kenneth J.

    2006-01-01

    Earth-science researchers need the capability to find relevant information by location and topic. Conventional geographic techniques that simply check whether polygons intersect can efficiently achieve a high recall on location, but can not achieve precision for ranking results in likely order of importance to the reader. A spatial overlay ranking based upon how well an object's footprint matches the search area provides a more effective way to spatially search a collection of reports, and avoids many of the problems associated with an 'in/out' (True/False) boolean search. Moreover, spatial overlay ranking appears to work well even when spatial extent is defined only by a simple bounding box.

  6. Testing of concrete by laser ablation

    DOEpatents

    Flesher, D.J.; Becker, D.L.; Beem, W.L.; Berry, T.C.; Cannon, N.S.

    1997-01-07

    A method is disclosed for testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed. 1 fig.

  7. Concrete density estimation by rebound hammer method

    SciTech Connect

    Ismail, Mohamad Pauzi bin Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri; Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin; Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin

    2016-01-22

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite.

  8. Testing of concrete by laser ablation

    DOEpatents

    Flesher, Dann J.; Becker, David L.; Beem, William L.; Berry, Tommy C.; Cannon, N. Scott

    1997-01-01

    A method of testing concrete in a structure in situ, by: directing a succession of pulses of laser radiation at a point on the structure so that each pulse effects removal of a quantity of concrete and transfers energy to the concrete; detecting a characteristic of energy which has been transferred to the concrete; determining, separately from the detecting step, the total quantity of concrete removed by the succession of pulses; and calculating a property of the concrete on the basis of the detected energy characteristic and the determined total quantity of concrete removed.

  9. Migrating corrosion inhibitor protection of concrete

    SciTech Connect

    Bjegovic, D.; Miksic, B.

    1999-11-01

    Migrating corrosion inhibitors (MCI) were developed to protect steel rebar from corrosion in concrete. They were designed to be incorporated as an admixture during concrete batching or used for surface impregnation of existing concrete structures. Two investigations are summarized. One studied the effectiveness of MCIs as a corrosion inhibitor for steel rebar when used as an admixture in fresh concrete mix. The other is a long-term study of MCI concrete impregnation that chronicles corrosion rates of rebar in concrete specimens. Based on data from each study, it was concluded that migrating corrosion inhibitors are compatible with concrete and effectively delay the onset of corrosion.

  10. Concrete density estimation by rebound hammer method

    NASA Astrophysics Data System (ADS)

    Ismail, Mohamad Pauzi bin; Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri; Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin

    2016-01-01

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite.

  11. Microstructural investigations on aerated concrete

    SciTech Connect

    Narayanan, N.; Ramamurthy, K.

    2000-03-01

    Aerated concrete is characterized by the presence of large voids deliberately included in its matrix to reduce the density. This study reports the investigations conducted on the structure of cement-based autoclaved aerated concrete (AAC) and non-AAC with sand or fly ash as the filler. The reasons for changes in compressive strength and drying shrinkage are explained with reference to the changes in the microstructure. Compositional analysis was carried out using XRD. It was observed that fly ash responds poorly to autoclaving. The process of pore refinement in fly ash mixes is discussed with reference to the formation of Hadley grains as well as fly ash hydration. The paste-void interface in aerated concrete investigated in relation to the paste-aggregate interface in normal concrete revealed the existence of an interfacial transition zone.

  12. PORTLAND CEMENT CONCRETE FOR ANTARCTICA.

    DTIC Science & Technology

    formulation of recommended procedures for batching, mixing, placing, and curing of portland cement concrete in Antarctica. The pertinent features of the mix and design and related procedures are given. (Author)

  13. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1990-03-13

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  14. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, J.J.; Elling, D.; Reams, W.

    1988-05-26

    A sprayable electrically conductive polymer concrete coating for vertical and overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt% calcined coke breeze, 40 wt% vinyl ester resin with 3.5 wt% modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag. 4 tabs.

  15. Electrically conductive polymer concrete coatings

    DOEpatents

    Fontana, Jack J.; Elling, David; Reams, Walter

    1990-01-01

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  16. Evaluation of Iron Aluminide Weld Overlays for Erosion-Corrosion Resistant Boiler Tube Coatings in Low NOx Boilers

    SciTech Connect

    Regina, J.R.; Lim, M.; Barbosa, N., DuPont, J.N.; Marder, A.R.

    2000-04-28

    Iron aluminide weld overlays containing ternary additions and thermal spray coatings are being investigated for corrosion protection of boiler tubes in Low NO{sub x} burners. The primary objective of the research is to identify overlay and thermal spray compositions that provide corrosion protection of waterwall boiler tubes.

  17. C-arm Cone Beam Computed Tomographic Needle Path Overlay for Fluoroscopic-Guided Placement of Translumbar Central Venous Catheters

    SciTech Connect

    Tam, Alda; Mohamed, Ashraf; Pfister, Marcus; Rohm, Esther; Wallace, Michael J.

    2009-07-15

    C-arm cone beam computed tomography is an advanced 3D imaging technology that is currently available on state-of-the-art flat-panel-based angiography systems. The overlay of cross-sectional imaging information can now be integrated with real-time fluoroscopy. This overlay technology was used to guide the placement of three percutaneous translumbar inferior vena cava catheters.

  18. Concrete waterproofing in nuclear industry.

    PubMed

    Scherbyna, Alexander N; Urusov, Sergei V

    2005-01-01

    One of the main points of aggregate safety during the transportation and storage of radioactive materials is to supply waterproofing for all constructions having direct contact with radiating substances and providing strength, seismic shielding etc. This is the problem with all waterside structures in nuclear industry and concrete installations in the treatment and storage of radioactive materials. In this connection, the problem of developing efficient techniques both for the repair of operating constructions and the waterproofing of new objects of the specified assignment is genuine. Various techniques of concrete waterproofing are widely applied in the world today. However, in conditions of radiation many of these techniques can bring not a profit but irreparable damage of durability and reliability of a concrete construction; for instance, when waterproofing materials contain organic constituents, polymers etc. Application of new technology or materials in basic construction elements requires in-depth analysis and thorough testing. The price of an error might be very large. A comparative analysis shows that one of the most promising types of waterproofing materials for radiation loaded concrete constructions is "integral capillary systems" (ICS). The tests on radiation, thermal and strength stability of ICS and ICS-treated concrete samples were initiated and fulfilled in RFNC-VNIITF. The main result is--ICS applying is increasing of waterproofing and strength properties of concrete in conditions of readiation The paper is devoted to describing the research strategy, the tests and their results and also to planning of new tests.

  19. Protective coatings for concrete

    SciTech Connect

    NAGY, KATHRYN L.; CYGAN, RANDALL T.; BRINKER, C. JEFFREY; SELLINGER, ALAN

    2000-05-01

    The new two-layer protective coating developed for monuments constructed of limestone or marble was applied to highway cement and to tobermorite, a component of cement, and tested in batch dissolution tests. The goal was to determine the suitability of the protective coating in retarding the weathering rate of concrete construction. The two-layer coating consists of an inner layer of aminoethylaminopropylsilane (AEAPS) applied as a 25% solution in methanol and an outer layer of A2** sol-gel. In previous work, this product when applied to calcite powders, had resulted in a lowering of the rate of dissolution by a factor of ten and was shown through molecular modeling to bind strongly to the calcite surface, but not too strongly so as to accelerate dissolution. Batch dissolution tests at 22 C of coated and uncoated tobermorite (1.1 nm phase) and powdered cement from Gibson Blvd. in Albuquerque indicated that the coating exhibits some protective behavior, at least on short time scales. However, the data suggest that the outer layer of sol-gel dissolves in the high-pH environment of the closed system of cement plus water. Calculated binding configuration and energy of AEAPS to the tobermorite surface suggests that AEAPS is well-suited as the inner layer binder for protecting tobermorite.

  20. Posterior open occlusion management by registration of overlay removable partial denture: A clinical report

    PubMed Central

    Nosouhian, Saeid; Davoudi, Amin; Derhami, Mohammad

    2015-01-01

    This clinical report describes prosthetic rehabilitation of posterior open bite relationship in a patient with several missing teeth and skeletal Class III malocclusion. Primary diagnostic esthetic evaluations were performed by mounting casts in centric relation and estimating lost vertical dimension of occlusion. Exclusive treatments were designated by applying overlay removable partial denture with external attachment systems for higher retentions. PMID:26929544

  1. Precision-guided surgical navigation system using laser guidance and 3D autostereoscopic image overlay.

    PubMed

    Liao, Hongen; Ishihara, Hirotaka; Tran, Huy Hoang; Masamune, Ken; Sakuma, Ichiro; Dohi, Takeyoshi

    2010-01-01

    This paper describes a precision-guided surgical navigation system for minimally invasive surgery. The system combines a laser guidance technique with a three-dimensional (3D) autostereoscopic image overlay technique. Images of surgical anatomic structures superimposed onto the patient are created by employing an animated imaging method called integral videography (IV), which can display geometrically accurate 3D autostereoscopic images and reproduce motion parallax without the need for special viewing or tracking devices. To improve the placement accuracy of surgical instruments, we integrated an image overlay system with a laser guidance system for alignment of the surgical instrument and better visualization of patient's internal structure. We fabricated a laser guidance device and mounted it on an IV image overlay device. Experimental evaluations showed that the system could guide a linear surgical instrument toward a target with an average error of 2.48 mm and standard deviation of 1.76 mm. Further improvement to the design of the laser guidance device and the patient-image registration procedure of the IV image overlay will make this system practical; its use would increase surgical accuracy and reduce invasiveness.

  2. Scalable P2P Overlays of Very Small Constant Degree: An Emerging Security Threat

    NASA Astrophysics Data System (ADS)

    Jelasity, Márk; Bilicki, Vilmos

    In recent years peer-to-peer (P2P) technology has been adopted by Internet-based malware as a fault tolerant and scalable communication medium for self-organization and survival. It has been shown that malicious P2P networks would be nearly impossible to uncover if they operated in a stealth mode, that is, using only a small constant number of fixed overlay connections per node for communication. While overlay networks of a small constant maximal degree are generally considered to be unscalable, we argue in this paper that it is possible to design them to be scalable, efficient and robust. This is an important finding from a security point of view: we show that stealth mode P2P malware that is very difficult to discover with state-of-the-art methods is a plausible threat. In this paper we discuss algorithms and theoretical results that support the scalability of stealth mode overlays, and we present realistic simulations using an event based implementation of a proof-of-concept system. Besides P2P botnets, our results are also applicable in scenarios where relying on a large number of overlay connections per node is not feasible because of cost or the limited number of communication channels available.

  3. Overlay Transmission System on Wireless LAN with RTS/CTS Exchange Taking into Account Timing Synchronization

    NASA Astrophysics Data System (ADS)

    Jeong, Kilsoo; Yano, Kazuto; Tsukamoto, Satoshi; Taromaru, Makoto

    This paper proposes a new overlay transmission system for wireless LAN with RTS/CTS exchange. Conventional timing synchronization schemes may fail in the presence of inter-system interference, because they have not been designed for overlay transmission. In the proposed system, a transmitter estimates the transmission timing of the next wireless LAN DATA frame, and then sends its DATA frame at almost the same time as the estimated transmission timing to easily establish timing synchronization at the receiver. Moreover, we employ a tapped delay line adaptive array antenna at both transmitter and receiver to effectively suppress interference due to overlay transmission in a rich multipath propagation environment. The frame error rate performances of the proposed system and the IEEE 802.11a wireless LAN are evaluated through computer simulations that assume an exponentially decaying 8-path non-line-of-sight fading channel and include a timing synchronization process. Simulation results demonstrate that the proposed system can achieve overlay transmission while avoiding interference in a rich multipath propagation environment.

  4. Colored Overlays Enhance Visual Perceptual Performance in Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Ludlow, A. K.; Wilkins, A. J.; Heaton, P.

    2008-01-01

    Children with autism spectrum disorders (ASD), together with controls matched for age and ability participated in three experiments that assessed the therapeutic benefit of colored overlays. The findings from the first experiment showed that a significantly greater proportion of children with ASD, than controls, increased reading speed when using…

  5. Assessing the Crossdisciplinarity of Technology-Enhanced Learning with Science Overlay Maps and Diversity Measures

    ERIC Educational Resources Information Center

    Kalz, Marco; Specht, Marcus

    2014-01-01

    This paper deals with the assessment of the crossdisciplinarity of technology-enhanced learning (TEL). Based on a general discussion of the concept interdisciplinarity and a summary of the discussion in the field, two empirical methods from scientometrics are introduced and applied. Science overlay maps and the Rao-Stirling diversity index are…

  6. Robotic weld overlay coatings for erosion control. Final technical progress report, July 1992--July 1995

    SciTech Connect

    Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1995-10-15

    The erosion behavior of weld overlay coatings has been studied. Eleven weld overlay alloys were deposited on 1018 steel substrates using the plasma arc welding process and erosion tested at 400{degrees}C at 90{degrees} and 30{degrees} particle impact angles. The microstructure of each coating was characterized before erosion testing. A relative ranking of the coatings erosion resistance was developed by determining the steady state erosion rates. Ultimet, Inconel-625, and 316L SS coatings showed the best erosion resistance at both impact angles. It was found that weld overlays that exhibit good abrasion resistance did not show good erosion resistance. Erosion tests were also performed for selected wrought materials with chemical composition similar to weld overlays. Eroded surfaces of the wrought and weld alloys were examined by Scanning Electron Microscopy (SEM). Microhardness tests were performed on the eroded samples below the erosion surface to determine size of the plastically deformed region. It was found that one group of coatings experienced significant plastic deformation as a result of erosion while the other did not. It was also established that, in the steady state erosion regime, the size of the plastically deformed region is constant.

  7. Semantic Overlays in Educational Content Networks--The hylOs Approach

    ERIC Educational Resources Information Center

    Engelhardt, Michael; Hildebrand, Arne; Lange, Dagmar; Schmidt, Thomas C.

    2006-01-01

    Purpose: The paper aims to introduce an educational content management system, Hypermedia Learning Objects System (hylOs), which is fully compliant to the IEEE LOM eLearning object metadata standard. Enabled through an advanced authoring toolset, hylOs allows the definition of instructional overlays of a given eLearning object mesh.…

  8. A Novel Approach to Overlay Multicasting Schemes for Multi-Hop Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Kang, Namhi; Oh, Jejun; Kim, Younghan

    Multicast is an efficient transport mechanism for group-based community communications and mobile ad-hoc networks (MANET) is recently regarded as a promising solution for supporting ubiquitous computing as an underlying network technology. However, it is challenging to deploy the multicast mechanism used in a wired network directly into MANET owing to scarce resources in wireless networks and unpredictable changes in network topology. Several multicast mechanisms have been proposed in the literature to overcome these limitations. In MANET, especially, overlay multicasting schemes present several advantages over network-based multicasting schemes. However we have observed a common limitation of previously proposed overlay multicasting schemes. They introduce redundant data transmissions that waste network bandwidth and the battery of relay nodes. The observation motivated us to propose an efficient way to create and maintain a “semi-overlay structure” that utilizes a few nonmember nodes selected as branch nodes. The proposed scheme, called “SOMRP (Semi-overlay multicast routing protocol),” has been evaluated by using extensive network simulation in two different scenarios, comparing the performance of SOMRP with two previously proposed schemes. Simulation results show that SOMRP outperforms the two schemes in terms of the packet delivery ratio, transmission cost and end-to-end delay.

  9. Passivation of hematite nanorod photoanodes with a phosphorus overlayer for enhanced photoelectrochemical water oxidation

    NASA Astrophysics Data System (ADS)

    Xiong, Dehua; Li, Wei; Wang, Xiaoguang; Liu, Lifeng

    2016-09-01

    Hematite (i.e., α-Fe2O3) nanorod photoanodes passivated with a phosphorus overlayer have been fabricated by decomposing sodium hypophosphite (NaH2PO2) at a low temperature over the hematite nanorod surface. Extensive scanning electron microscopy, transmission electron microscopy, x-ray diffractometry and UV-vis spectroscopy characterizations confirm that conformal deposition of an amorphous phosphorus overlayer does not change the crystal structure, morphology, and optical absorption properties of hematite photoanodes. X-ray photoelectron spectroscopy reveals that phosphorus in the deposited overlayer exists in an oxidized state. Comprehensive steady-state polarization, transient photocurrent response, and impedance spectroscopy measurements as well as Mott-Schottky analysis manifest that the phosphorus overlayer is able to effectively passivate surface states and suppress electron-hole recombination, substantially enhancing the photocurrent for water oxidation. Combining the phosphorization treatment with two-step thermal activation, a photocurrent density of 1.1 mA cm-2 is achieved at 1.23 V versus reversible hydrogen electrode under illumination of 100 mW cm-2, ca 55 times higher than that of the non-activated pristine hematite photoanode measured under the same conditions. The simple and fast phosphorization strategy we present here can be readily applied to passivate surfaces of other semiconductor photoelectrodes to improve their photoelectrochemical performance.

  10. The Effect of Coloured Overlays on Reading Ability in Children with Autism

    ERIC Educational Resources Information Center

    Ludlow, Amanda K.; Wilkins, Arnold J.; Heaton, Pam

    2006-01-01

    Abnormalities of colour perception in children with autistic spectrum disorders have been widely reported anecdotally. However, there is little empirical data linking difficulties in colour perception with academic achievement. The Wilkins Rate of Reading Test was administered with and without "Intuitive Coloured Overlays" to 19 children with…

  11. Surface electronic structures of Ba overlayers on W(100), W(110), and W(111)

    NASA Astrophysics Data System (ADS)

    Ibrahim, Z. A.; Lee, M. J. G.

    2007-10-01

    The total energy distributions (TEDs) in field emission (FE) and photofield emission (PFE) and the work functions have been measured at room temperature for Ba adsorbed on W(100), W(110), and W(111) in the range of coverage from 0 to 1 ML (monolayer). We observe two initial state peaks and three final state peaks on W(100)/Ba , six initial state peaks and one final state peak on W(110)/Ba , and two initial state peaks and two final state peaks on W(111)/Ba . We extend the full-potential linear augmented plane wave method for the electronic structures of periodic lattices to calculate the emission current in FE and surface PFE at a metal-adsorbate-vacuum interface. Our calculations account for the energies of all of the initial state features observed experimentally in FE and surface PFE from clean W(100), in PFE and angle-resolved inverse photoemission spectroscopy from W(100)/Ba at 1 ML, and for all of the peaks observed in FE, surface PFE, and photoemission from W(110)/Ba at 0.6 ML and from W(111)/Ba at 1 ML. The dz2 -like surface states of the Swanson hump [L. W. Swanson and L. C. Crouser, Phys. Rev. Lett. 16, 389 (1966)] of clean W(100) hybridize with s -like states of the c(2×2) overlayer and are shifted by -1.60eV to yield a prominent peak in PFE. An isolated Ba c(2×2) layer is found to be weakly metallic; the metallicity is greatly enhanced when it is adsorbed on a W(100) substrate. The TEDs in PFE from the atomically less dense overlayer W(110)/Ba (2×2) are dominated by substrate-overlayer interactions, while those from the atomically denser overlayer W(111)/Ba (1×1) are dominated by interactions within the overlayer. Our results yield evidence that above 1/3 ML Ba coverage on W(111), which corresponds to a commensurate (31/2×31/2)R30° overlayer, the interstitial sites fill in randomly to form a commensurate (1×1) overlayer at 1 ML coverage.

  12. High order overlay modeling and APC simulation with Zernike-Legendre polynomials

    NASA Astrophysics Data System (ADS)

    Ju, JawWuk; Kim, MinGyu; Lee, JuHan; Sherwin, Stuart; Hoo, George; Choi, DongSub; Lee, Dohwa; Jeon, Sanghuck; Lee, Kangsan; Tien, David; Pierson, Bill; Robinson, John C.; Levy, Ady; Smith, Mark D.

    2015-03-01

    Feedback control of overlay errors to the scanner is a well-established technique in semiconductor manufacturing [1]. Typically, overlay errors are measured, and then modeled by least-squares fitting to an overlay model. Overlay models are typically Cartesian polynomial functions of position within the wafer (Xw, Yw), and of position within the field (Xf, Yf). The coefficients from the data fit can then be fed back to the scanner to reduce overlay errors in future wafer exposures, usually via a historically weighted moving average. In this study, rather than using the standard Cartesian formulation, we examine overlay models using Zernike polynomials to represent the wafer-level terms, and Legendre polynomials to represent the field-level terms. Zernike and Legendre polynomials can be selected to have the same fitting capability as standard polynomials (e.g., second order in X and Y, or third order in X and Y). However, Zernike polynomials have the additional property of being orthogonal over the unit disk, which makes them appropriate for the wafer-level model, and Legendre polynomials are orthogonal over the unit square, which makes them appropriate for the field-level model. We show several benefits of Zernike/Legendre-based models in this investigation in an Advanced Process Control (APC) simulation using highly-sampled fab data. First, the orthogonality property leads to less interaction between the terms, which makes the lot-to-lot variation in the fitted coefficients smaller than when standard polynomials are used. Second, the fitting process itself is less coupled - fitting to a lower-order model, and then fitting the residuals to a higher order model gives very similar results as fitting all of the terms at once. This property makes fitting techniques such as dual pass or cascading [2] unnecessary, and greatly simplifies the options available for the model recipe. The Zernike/Legendre basis gives overlay performance (mean plus 3 sigma of the residuals

  13. Differential Linewidth Structures For Overlay Measurements At 0.25 Micron Ground Rules

    NASA Astrophysics Data System (ADS)

    Ashton, C. J.

    1987-04-01

    Direct write E-beam lithography at 0.25 micron ground rules will soon be a practical reality. Other technologies such as X-Ray lithography are also moving rapidly towards these dimensions. This im-plies overlay tolerances at the level of 1 sigma = 25 nm. Characterization of tool overlay performance (particularly systematic error components) in this regime is a challenging and important metrology problem. A combination of carefully designed test structures, high quality fabrication, and the best available measuring instrumentation will be a minimum requirement for adequately addressing this need. This paper describes a study of self-compensating differential linewidth structures for such overlay measurements. These structures require only relative (not absolute) dimensional measurements, and linewidth comparisons are made only over very short physical distances. Therefore, the results are in principle insensitive to systematic errors and time-dependent drift in the metrology tool, and to systematic variations in processing uniformity across a macroscopic substrate. Design and fabrication of the test structures is discussed. The test structures used were primarily designed for use with an electrical linewidth measurement tool, but several more "traditional" overlay test structures were also built in for comparison purposes. The structures were exposed on an IBM EL-3 direct write E-beam tool with 0.25 - 0.5 micron ground rule capability, and delineated by RIE of 200 nm of doped polysilicon. The processing was optimized to produce lines with sharply defined vertical edges. Such lines give excellent signals in optical and SEM linewidth measurement tools, and so are well suited for comparison of these techniques with electrical measurements. Comparisons of linewidth differences measured electrically, laser optically, and on an SEM show excellent agreement. The 1 sigma measurement error is found to be in the range 7 - 9 nm for all of the three tools investigated. This

  14. Nanogranular origin of concrete creep.

    PubMed

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-06-30

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium-silicate-hydrates (C-S-H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C-S-H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C-S-H forms: low density, high density, ultra-high density. We demonstrate that the creep rate ( approximately 1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years.

  15. Nanogranular origin of concrete creep

    PubMed Central

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-01-01

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium–silicate–hydrates (C–S–H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C–S–H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C–S–H forms: low density, high density, ultra-high density. We demonstrate that the creep rate (≈1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years. PMID:19541652

  16. 27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, ...

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

    27. DIVERSION STRUCTURE WITH CONCRETE SIDEWALLS AND CONCRETE CHANNEL BEYOND, A SHORT DISTANCE WEST OF D STREET ABOUT ONE-QUARTER MILE SOUTH OF 9TH AVENUE (SECTION 26). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

  17. Two Dimensional Array Based Overlay Network for Balancing Load of Peer-to-Peer Live Video Streaming

    NASA Astrophysics Data System (ADS)

    Faruq Ibn Ibrahimy, Abdullah; Rafiqul, Islam Md; Anwar, Farhat; Ibn Ibrahimy, Muhammad

    2013-12-01

    The live video data is streaming usually in a tree-based overlay network or in a mesh-based overlay network. In case of departure of a peer with additional upload bandwidth, the overlay network becomes very vulnerable to churn. In this paper, a two dimensional array-based overlay network is proposed for streaming the live video stream data. As there is always a peer or a live video streaming server to upload the live video stream data, so the overlay network is very stable and very robust to churn. Peers are placed according to their upload and download bandwidth, which enhances the balance of load and performance. The overlay network utilizes the additional upload bandwidth of peers to minimize chunk delivery delay and to maximize balance of load. The procedure, which is used for distributing the additional upload bandwidth of the peers, distributes the additional upload bandwidth to the heterogeneous strength peers in a fair treat distribution approach and to the homogeneous strength peers in a uniform distribution approach. The proposed overlay network has been simulated by Qualnet from Scalable Network Technologies and results are presented in this paper.

  18. IMPERMEABLE THIN AL2O3 OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

    SciTech Connect

    Scott X. Mao

    2003-12-16

    To improve the hot corrosion resistance of YSZ thermal barrier coatings, a 25 {micro}m and a 2 {micro}m thick Al{sub 2}O{sub 3} overlay were deposited by HVOF thermal spray and by sol-gel coating method, respectively, onto to the surface of YSZ coating. Indenter test was employed to investigate the spalling of YSZ with and without Al{sub 2}O{sub 3} overlay after hot corrosion. The results showed that Al{sub 2}O{sub 3} overlay acted as a barrier against the infiltration of the molten salt into the YSZ coating during exposure, thus significantly reduced the amount of M-phase of ZrO{sub 2} in YSZ coating. However, a thick Al{sub 2}O{sub 3} overlay was harmful for TBC by increasing compressive stress which causes crack and spalling of YSZ coating. As a result, a dense and thin Al{sub 2}O{sub 3} overlay is critical for simultaneously preventing YSZ from hot corrosion and spalling. In the next reporting period, we will measure or calculate the residue stress within Al{sub 2}O{sub 3} overlay and YSZ coating to study the mechanism of effect of Al{sub 2}O{sub 3} overlay on spalling of YSZ coating.

  19. Dynamic Increase Factors for Concrete

    DTIC Science & Technology

    1998-08-01

    Strain Rate Effects on Fracture, S. Mindess and S.P. Shah, editors, December 1985, pp. 1-13. 35. Weerheijm, J., Reinhardt, H.W., “Modelling of...Out of Anchored Reinforcing Bars,” Transactions of the Japan Concrete Institute, Vol. 15, 1994, pp. 459-466. 50. Bentur, A. S., S. Mindess and N. P...Society Symposia Proceedings Vol. 64 (S. Mindess and S. P. Shah, eds.), Pittsburgh, 1986, pp. 225-234. 51. Banthia, N. P., “Impact Resistance of Concrete

  20. Assessing the concreteness of relational representation.

    PubMed

    Rein, Jonathan R; Markman, Arthur B

    2010-11-01

    Research has shown that people's ability to transfer abstract relational knowledge across situations can be heavily influenced by the concrete objects that fill relational roles. This article provides evidence that the concreteness of the relations themselves also affects performance. In 3 experiments, participants viewed simple relational patterns of visual objects and then identified these same patterns under a variety of physical transformations. Results show that people have difficulty generalizing to novel concrete forms of abstract relations, even when objects are unchanged. This suggests that stimuli are initially represented as concrete relations by default. In the 2nd and 3rd experiments, the number of distinct concrete relations in the training set was increased to promote more abstract representation. Transfer improved for novel concrete relations but not for other transformations such as object substitution. Results indicate that instead of automatically learning abstract relations, people's relational representations preserve all properties that appear consistently in the learning environment, including concrete objects and concrete relations.

  1. Holistic overlay control for multi-patterning process layers at the 10nm and 7nm nodes

    NASA Astrophysics Data System (ADS)

    Verstappen, Leon; Mos, Evert; Wardenier, Peter; Megens, Henry; Schmitt-Weaver, Emil; Bhattacharyya, Kaustuve; Adam, Omer; Grzela, Grzegorz; van Heijst, Joost; Willems, Lotte; Wildenberg, Jochem; Ignatova, Velislava; Chen, Albert; Elich, Frank; Rajasekharan, Bijoy; Vergaij-Huizer, Lydia; Lewis, Brian; Kea, Marc; Mulkens, Jan

    2016-03-01

    Multi-patterning lithography at the 10-nm and 7-nm nodes is driving the allowed overlay error down to extreme low values. Advanced high order overlay correction schemes are needed to control the process variability. Additionally the increase of the number of split layers results in an exponential increase of metrology complexity of the total overlay and alignment tree. At the same time, the process stack includes more hard-mask steps and becomes more and more complex, with as consequence that the setup and verification of the overlay metrology recipe becomes more critical. All of the above require a holistic approach that addresses total overlay optimization from process design to process setup and control in volume manufacturing. In this paper we will present the holistic overlay control flow designed for 10-nm and 7-nm nodes and illustrate the achievable ultimate overlay performance for a logic and DRAM use case. As figure 1 illustrates we will explain the details of the steps in the holistic flow. Overlay accuracy is the driver for target design and metrology tool optimization like wavelength and polarization. We will show that it is essential to include processing effects like etching and CMP which can result in a physical asymmetry of the bottom grating of diffraction based overlay targets. We will introduce a new method to create a reference overlay map, based on metrology data using multiple wavelengths and polarization settings. A similar approach is developed for the wafer alignment step. The overlay fingerprint correction using linear or high order correction per exposure (CPE) has a large amount of parameters. It is critical to balance the metrology noise with the ultimate correction model and the related metrology sampling scheme. Similar approach is needed for the wafer align step. Both for overlay control as well as alignment we have developed methods which include efficient use of metrology time, available for an in the litho-cluster integrated

  2. Assessing Workability Complaints in Mass Concrete Construction

    DTIC Science & Technology

    1993-04-01

    up primarily of rigid pipes. It appears that poorly maintained vibrators are frequently proposed for use in consolidating mass concrete . Use of such... vibrators can give the false im- pression of unworkable concrete and result in poorly consolidated concrete . Only vibrators in good operating...units is presented on page vi. 5 Chapt~er 2 Survey Results The survey also indicated that mass concrete is frequently vibrated improp- erly. Improper

  3. Corrosion Behavior of Steel Fibrous Concrete

    DTIC Science & Technology

    1977-05-01

    Crvtaiue wi ,rerse sido it necessaty m’d Identify by block number) steel fibrous concrete corrosion cracked fibrous concrete 20 ABST RACT (Continue...dissolved gas in liq- Although chloride ions affect the rate of steel corro- uids. sion in concrete , corrosion can occur without them. Verbeck has...repcrted that steel subjected to a concrete Corrosion of steel will not occur without water. Not environment normally develops a protective oxide film

  4. Molecular Survey of Concrete Biofilm Microbial Communities

    EPA Science Inventory

    Although several studies have shown that bacteria can deteriorate concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different microbial communities associated with concrete biofilms using 16S rRNA g...

  5. RADON GENERATION AND TRANSPORT IN AGED CONCRETE

    EPA Science Inventory

    The report gives results of a characterization of radon generation and transport in Florida concretes sampled from 12- to 45-year-old residential slabs. It also compares measurements from old concrete samples to previous measurements on newly poured Florida residential concretes....

  6. Lightweight concrete with enhanced neutron shielding

    SciTech Connect

    Brindza, Paul Daniel; Metzger, Bert Clayton

    2016-09-13

    A lightweight concrete containing polyethylene terephthalate in an amount of 20% by total volume. The concrete is enriched with hydrogen and is therefore highly effective at thermalizing neutrons. The concrete can be used independently or as a component of an advanced neutron radiation shielding system.

  7. 9 CFR 91.26 - Concrete flooring.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  8. 9 CFR 91.26 - Concrete flooring.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  9. 9 CFR 91.26 - Concrete flooring.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  10. 9 CFR 91.26 - Concrete flooring.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  11. 9 CFR 91.26 - Concrete flooring.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  12. A hierarchical P2P overlay network for interest-based media contents lookup

    NASA Astrophysics Data System (ADS)

    Lee, HyunRyong; Kim, JongWon

    2006-10-01

    We propose a P2P (peer-to-peer) overlay architecture, called IGN (interest grouping network), for contents lookup in the DHC (digital home community), which aims to provide a formalized home-network-extended construction of current P2P file sharing community. The IGN utilizes the Chord and de Bruijn graph for its hierarchical overlay network construction. By combining two schemes and by inheriting its features, the IGN efficiently supports contents lookup. More specifically, by introducing metadata-based lookup keyword, the IGN offers detailed contents lookup that can reflect the user interests. Moreover, the IGN tries to reflect home network environments of DHC by utilizing HG (home gateway) of each home network as a participating node of the IGN. Through experimental and analysis results, we show that the IGN is more efficient than Chord, a well-known DHT (distributed hash table)-based lookup protocol.

  13. Automatic Generation of Overlays and Offset Values Based on Visiting Vehicle Telemetry and RWS Visuals

    NASA Technical Reports Server (NTRS)

    Dunne, Matthew J.

    2011-01-01

    The development of computer software as a tool to generate visual displays has led to an overall expansion of automated computer generated images in the aerospace industry. These visual overlays are generated by combining raw data with pre-existing data on the object or objects being analyzed on the screen. The National Aeronautics and Space Administration (NASA) uses this computer software to generate on-screen overlays when a Visiting Vehicle (VV) is berthing with the International Space Station (ISS). In order for Mission Control Center personnel to be a contributing factor in the VV berthing process, computer software similar to that on the ISS must be readily available on the ground to be used for analysis. In addition, this software must perform engineering calculations and save data for further analysis.

  14. Robotic weld overlay coatings for erosion control. [Quarterly report, July--September 1993

    SciTech Connect

    Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1993-10-20

    In the previous period of work, twelve overlay hardfacing alloys were selected for erosion testing based upon a literature review. All twelve coatings were deposited on 1018 steel substrates using the plasma arc welding process. Ten samples from each coating were prepared for erosion testing. The coating deposition and sample preparation procedures were described in the previous quarterly report. During the past quarter, all the coatings were erosion tested at 400 C. The erosion resistance of each coating was evaluated by determining the steady state erosion rate. In addition, the microstructure of each coating was characterized before and after the erosion tests. This progress report describes the erosion test results and coating microstructures. Also, a preliminary analysis on the relationships, between weld overlay coating hardness, microstructure, and erosion resistance will be discussed.

  15. A Hybrid P2P Overlay Network for Non-strictly Hierarchically Categorized Content

    NASA Astrophysics Data System (ADS)

    Wan, Yi; Asaka, Takuya; Takahashi, Tatsuro

    In P2P content distribution systems, there are many cases in which the content can be classified into hierarchically organized categories. In this paper, we propose a hybrid overlay network design suitable for such content called Pastry/NSHCC (Pastry for Non-Strictly Hierarchically Categorized Content). The semantic information of classification hierarchies of the content can be utilized regardless of whether they are in a strict tree structure or not. By doing so, the search scope can be restrained to any granularity, and the number of query messages also decreases while maintaining keyword searching availability. Through simulation, we showed that the proposed method provides better performance and lower overhead than unstructured overlays exploiting the same semantic information.

  16. The Effects of a Dynamic Spectrum Access Overlay in LTE-Advanced Networks

    SciTech Connect

    Juan D. Deaton; Ryan E. Irwin; Luiz A. DaSilva

    2011-05-01

    As early as 2014, mobile network operators’ spectral capacity will be overwhelmed by the demand brought on by new devices and applications. To augment capacity and meet this demand, operators may choose to deploy a Dynamic Spectrum Access (DSA) overlay. The signaling and functionality required by such an overlay have not yet been fully considered in the architecture of the planned Long Term Evolution Advanced (LTE+) networks. This paper presents a Spectrum Accountability framework to be integrated into LTE+ architectures, defining specific element functionality, protocol interfaces, and signaling flow diagrams required to enforce the rights and responsibilities of primary and secondary users. We also quantify, through integer programs, the benefits of using DSA channels to augment capacity under a scenario in which LTE+ network can opportunistically use TV and GSM spectrum. The framework proposed here may serve as a guide in the development of future LTE+ network standards that account for DSA.

  17. Overlay coating degradation by simultaneous oxidation and coating/substrate interdiffusion

    SciTech Connect

    Nesbitt, J.A.

    1984-08-01

    This paper describes a numerical model which simulates diffusion, associated with overlay-coating degradation by oxidation and coating/substrate interdiffusion. Such nickel-chromium-aluminum overlays are used in high temperature turbine applications. Inputs to the model were the chromium and aluminum content of coating and substrate, ternary diffusivities, and various oxide spalling parameters. The model predicts the chromium and aluminum concentrations in the coating and substrate after any number of oxidation/thermal cycles. The model also predicts coating failure based on the ability of the coating to supply sufficient aluminum to the oxide scale. The validity of the model was confirmed by comparison of the predicted and measured concentration/distance profiles.

  18. Overlay metrology for dark hard mask process: simulation and experiment study

    NASA Astrophysics Data System (ADS)

    Shin, Jangho; Chalykh, Roman; Kang, Hyunjae; Kim, SeongSue; Lee, SukJoo; Cho, Han-Ku

    2007-03-01

    Simulation and experimental study results are reported to solve align/overlay problem in dark hard mask process in lithography. For simulation part, an in-house simulator, which is based on rigorous coupled wave analysis and Fourier optics method of high NA imaging, is used. According to the simulation and experiment study, image quality of alignment and overlay marks can be optimized by choosing hard mask and sub-film thickness carefully for a given process condition. In addition, it is important to keep the specification of film thickness uniformity within a certain limit. Simulation results are confirmed by experiment using the state of art memory process in Samsung semiconductor R&D facility.

  19. Concrete Finisher Program. Apprenticeship Training.

    ERIC Educational Resources Information Center

    Alberta Learning, Edmonton. Apprenticeship and Industry Training.

    This document presents information about the apprenticeship training program of Alberta, Canada, in general and the concrete finishing program in particular. The first part of the document discusses the following items: Alberta's apprenticeship and industry training system; the apprenticeship and industry training committee structure; local…

  20. High temperature polymer concrete compositions

    SciTech Connect

    Fontana, J.J.; Reams, W.

    1985-02-19

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers is a liquid system.

  1. Quick-setting concrete and a method for making quick-setting concrete

    DOEpatents

    Wagh, Arun S.; Singh, Dileep; Pullockaran, Jose D.; Knox, Lerry

    1997-01-01

    A method for producing quick setting concrete is provided comprising hydrng a concrete dry mixture with carbonate solution to create a slurry, and allowing the slurry to cure. The invention also provides for a quick setting concrete having a predetermined proportion of CaCO.sub.3 of between 5 and 23 weight percent of the entire concrete mixture, and whereby the concrete has a compression strength of approximately 4,000 pounds per square inch (psi) within 24 hours after pouring.

  2. Microeconomics-based resource allocation in overlay networks by using non-strategic behavior modeling

    NASA Astrophysics Data System (ADS)

    Analoui, Morteza; Rezvani, Mohammad Hossein

    2011-01-01

    Behavior modeling has recently been investigated for designing self-organizing mechanisms in the context of communication networks in order to exploit the natural selfishness of the users with the goal of maximizing the overall utility. In strategic behavior modeling, the users of the network are assumed to be game players who seek to maximize their utility with taking into account the decisions that the other players might make. The essential difference between the aforementioned researches and this work is that it incorporates the non-strategic decisions in order to design the mechanism for the overlay network. In this solution concept, the decisions that a peer might make does not affect the actions of the other peers at all. The theory of consumer-firm developed in microeconomics is a model of the non-strategic behavior that we have adopted in our research. Based on it, we have presented distributed algorithms for peers' "joining" and "leaving" operations. We have modeled the overlay network as a competitive economy in which the content provided by an origin server can be viewed as commodity and the origin server and the peers who multicast the content to their downside are considered as the firms. On the other hand, due to the dual role of the peers in the overlay network, they can be considered as the consumers as well. On joining to the overlay economy, each peer is provided with an income and tries to get hold of the service regardless to the behavior of the other peers. We have designed the scalable algorithms in such a way that the existence of equilibrium price (known as Walrasian equilibrium price) is guaranteed.

  3. The Corrosion and Corrosion Fatigue Behavior of Nickel Based Alloy Weld Overlay and Coextruded Claddings

    NASA Astrophysics Data System (ADS)

    Stockdale, Andrew

    The use of low NOx boilers in coal fired power plants has resulted in sulfidizing corrosive conditions within the boilers and a reduction in the service lifetime of the waterwall tubes. As a solution to this problem, Ni-based weld overlays are used to provide the necessary corrosion resistance however; they are susceptible to corrosion fatigue. There are several metallurgical factors which give rise to corrosion fatigue that are associated with the localized melting and solidification of the weld overlay process. Coextruded coatings offer the potential for improved corrosion fatigue resistance since coextrusion is a solid state coating process. The corrosion and corrosion fatigue behavior of alloy 622 weld overlays and coextruded claddings was investigated using a Gleeble thermo-mechanical simulator retrofitted with a retort. The experiments were conducted at a constant temperature of 600°C using a simulated combustion gas of N2-10%CO-5%CO2-0.12%H 2S. An alternating stress profile was used with a minimum tensile stress of 0 MPa and a maximum tensile stress of 300 MPa (ten minute fatigue cycles). The results have demonstrated that the Gleeble can be used to successfully simulate the known corrosion fatigue cracking mechanism of Ni-based weld overlays in service. Multilayer corrosion scales developed on each of the claddings that consisted of inner and outer corrosion layers. The scales formed by the outward diffusion of cations and the inward diffusion of sulfur and oxygen anions. The corrosion fatigue behavior was influenced by the surface finish and the crack interactions. The initiation of a large number of corrosion fatigue cracks was not necessarily detrimental to the corrosion fatigue resistance. Finally, the as-received coextruded cladding exhibited the best corrosion fatigue resistance.

  4. In-die photomask registration and overlay metrology with PROVE using 2D correlation methods

    NASA Astrophysics Data System (ADS)

    Seidel, D.; Arnz, M.; Beyer, D.

    2011-11-01

    According to the ITRS roadmap, semiconductor industry drives the 193nm lithography to its limits, using techniques like double exposure, double patterning, mask-source optimization and inverse lithography. For photomask metrology this translates to full in-die measurement capability for registration and critical dimension together with challenging specifications for repeatability and accuracy. Especially, overlay becomes more and more critical and must be ensured on every die. For this, Carl Zeiss SMS has developed the next generation photomask registration and overlay metrology tool PROVE® which serves the 32nm node and below and which is already well established in the market. PROVE® features highly stable hardware components for the stage and environmental control. To ensure in-die measurement capability, sophisticated image analysis methods based on 2D correlations have been developed. In this paper we demonstrate the in-die capability of PROVE® and present corresponding measurement results for shortterm and long-term measurements as well as the attainable accuracy for feature sizes down to 85nm using different illumination modes and mask types. Standard measurement methods based on threshold criteria are compared with the new 2D correlation methods to demonstrate the performance gain of the latter. In addition, mask-to-mask overlay results of typical box-in-frame structures down to 200nm feature size are presented. It is shown, that from overlay measurements a reproducibility budget can be derived that takes into account stage, image analysis and global effects like mask loading and environmental control. The parts of the budget are quantified from measurement results to identify critical error contributions and to focus on the corresponding improvement strategies.

  5. Novel indazole non-nucleoside reverse transcriptase inhibitors using molecular hybridization based on crystallographic overlays.

    PubMed

    Jones, Lyn H; Allan, Gill; Barba, Oscar; Burt, Catherine; Corbau, Romuald; Dupont, Thomas; Knöchel, Thorsten; Irving, Steve; Middleton, Donald S; Mowbray, Charles E; Perros, Manos; Ringrose, Heather; Swain, Nigel A; Webster, Robert; Westby, Mike; Phillips, Chris

    2009-02-26

    A major problem associated with non-nucleoside reverse transcriptase inhibitors (NNRTIs) for the treatment of HIV is their lack of resilience to mutations in the reverse transcriptase (RT) enzyme. Using structural overlays of the known inhibitors efavirenz and capravirine complexed in RT as a starting point, and structure-based drug design techniques, we have created a novel series of indazole NNRTIs that possess excellent metabolic stability and mutant resilience.

  6. Effect of oil overlay on inhibition potential of roscovitine in sheep cumulus-oocyte complexes.

    PubMed

    Crocomo, L F; Marques Filho, W C; Ulian, C M V; Branchini, N S; Silva, D T; Ackermann, C L; Landim-Alvarenga, F C; Bicudo, S D

    2015-06-01

    Inhibitors of cyclin-dependent kinases, as roscovitine, have been used to prevent the spontaneous resumption of meiosis in vitro and to improve the oocyte developmental competence. In this study, the interference of oil overlay on the reversible arrest capacity of roscovitine in sheep oocytes as well as its effects on cumulus expansion was evaluated. For this, cumulus-oocyte complexes (COCs) were cultured for 20 h in TCM 199 with 10% foetal bovine serum (Control) containing 75 μm roscovitine (Rosco). Subsequently, they were in vitro matured (IVM) for further 18 h in inhibitor-free medium with LH and FSH. The culture was performed in Petri dishes under mineral oil (+) or in 96 well plates without oil overlay (-) at 38.5°C and 5% CO2 . At 20 and 38 h, the cumulus expansion and nuclear maturation were evaluated under stereomicroscope and by Hoechst 33342 staining, respectively. No group presented cumulus expansion at 20 h. After additional culture with gonadotrophins, a significant rate of COCs from both Control groups (+/-) exhibited total expansion while in both Rosco groups (+/-) the partial expansion prevailed. Among the oocytes treated with roscovitine, 65.2% were kept at GV in the absence of oil overlay while 40.6% of them reached MII under oil cover (p < 0.05). This meiotic arrest was reversible, and proper meiosis progression also occurred in the Control groups (+/-). So, the culture system without oil overlay improved the meiotic inhibition promoted by roscovitine without affecting the cumulus expansion rate or the subsequent meiosis progression.

  7. Monoplane 3D Overlay Roadmap versus Conventional Biplane 2D Roadmap Technique for Neurointervenional Procedures

    PubMed Central

    Jang, Dong-Kyu; Stidd, David A.; Schafer, Sebastian; Chen, Michael; Moftakhar, Roham

    2016-01-01

    Purpose We investigated whether a 3D overlay roadmap using monoplane fluoroscopy offers advantages over a conventional 2D roadmap using biplane fluoroscopy during endovascular aneurysm treatment. Materials and Methods A retrospective chart review was conducted for 131 consecutive cerebral aneurysm embolizations by three neurointerventionalists at a single institution. Allowing for a transition period, the periods from January 2012 to August 2012 (Time Period 1) and February 2013 to July 2013 (Time Period 2) were analyzed for radiation exposure, contrast administration, fluoroscopy time, procedure time, angiographic results, and perioperative complications. Two neurointerventionalists (Group 1) used a conventional 2D roadmap for both Time Periods, and one neurointerventionalist (Group 2) transitioned from a 2D roadmap during Time Period 1 to a 3D overlay roadmap during Time Period 2. Results During Time Period 2, Group 2 demonstrated reduced fluoroscopy time (p<0.001), procedure time (P=0.023), total radiation dose (p=0.001), and fluoroscopy dose (P=0.017) relative to Group 1. During Time Period 2, there was no difference of immediate angiographic results and procedure complications between the two groups. Through the transition from Time Period 1 to Time Period 2, Group 2 demonstrated decreased fluoroscopy time (p< 0.001), procedure time (p=0.022), and procedure complication rate (p=0.041) in Time Period 2 relative to Time Period 1. Conclusion The monoplane 3D overlay roadmap technique reduced fluoroscopy dose and fluoroscopy time during neurointervention of cerebral aneurysms with similar angiographic occlusions and complications rate relative to biplane 2D roadmap, which implies possible compensation of limitations of monoplane fluoroscopy by 3D overlay technique. PMID:27621947

  8. Ab initio study of Co and Ni under uniaxial and biaxial loading and in epitaxial overlayers

    NASA Astrophysics Data System (ADS)

    Zelený, M.; Legut, D.; Šob, M.

    2008-12-01

    A detailed theoretical study of structural and magnetic behaviors of cubic cobalt and nickel along the bcc-fcc (Bain) transformation paths as well as of hcp cobalt and nickel loaded uniaxially along the [0001] direction at various atomic volumes is presented. The total energies are calculated by spin-polarized full-potential linearized augmented plane-wave method within the generalized gradient approximation and are displayed in contour plots as functions of tetragonal or hcp c/a ratio and atomic volume; the borderlines between the ferromagnetic and nonmagnetic phases are shown. Stability of possible ferromagnetic phases of bcc nickel is analyzed. The calculated contour plots are used to explain and predict the lattice parameters and magnetic states of tetragonal and hcp cobalt and nickel overlayers on various (001) or (111) substrates, respectively. In case of tetragonally deformed structures, the stresses needed to keep the thin films coherent with the substrates are also determined and all Co and Ni overlayers on (001) cubic substrates are predicted to be ferromagnetic. The agreement of available experimental data for Co and Ni overlayers with the results of bulk calculations is remarkable and suggests that the geometrical effect of the substrate, i.e., imposing the lattice dimensions of the substrate in the plane of the film to the film material, is one of the most important factors determining the structure and properties of the film. In this way, the lattice parameters of Co and Ni overlayers may be very well understood in terms of properties of appropriately deformed bulk Co and Ni.

  9. XPS investigation of thin SiO x and SiO xN y overlayers

    NASA Astrophysics Data System (ADS)

    Birer, Ö.; Sayan, Ş.; Süzer, Ş.; Aydınlı, A.

    1999-05-01

    Angle-resolved XPS is used to determine the thickness and the uniformity of the chemical composition with respect to oxygen and nitrogen of the very thin silicon oxide and oxynitride overlayers grown on silicon.

  10. Study of spread spectrum multiple access systems for satellite communications with overlay on current services: Executive summary

    NASA Technical Reports Server (NTRS)

    Ha, Tri T.; Pratt, Timothy

    1987-01-01

    Two different methods of generating spread spectrum signals for an overlay service are discussed, and the data rate and efficiency which can be achieved while maintaining low interference with existing traffic are examined.

  11. Use of the Soft-agar Overlay Technique to Screen for Bacterially Produced Inhibitory Compounds

    PubMed Central

    Hockett, Kevin L.; Baltrus, David A.

    2017-01-01

    The soft-agar overlay technique was originally developed over 70 years ago and has been widely used in several areas of microbiological research, including work with bacteriophages and bacteriocins, proteinaceous antibacterial agents. This approach is relatively inexpensive, with minimal resource requirements. This technique consists of spotting supernatant from a donor strain (potentially harboring a toxic compound(s)) onto a solidified soft agar overlay that is seeded with a bacterial test strain (potentially sensitive to the toxic compound(s)). We utilized this technique to screen a library of Pseudomonas syringae strains for intraspecific killing. By combining this approach with a precipitation step and targeted gene deletions, multiple toxic compounds produced by the same strain can be differentiated. The two antagonistic agents commonly recovered using this technique are bacteriophages and bacteriocins. These two agents can be differentiated using two simple additional tests. Performing a serial dilution on a supernatant containing bacteriophage will result in individual plaques becoming less in number with greater dilution, whereas serial dilution of a supernatant containing bacteriocin will result a clearing zone that becomes uniformly more turbid with greater dilution. Additionally, a bacteriophage will produce a clearing zone when spotted onto a fresh soft agar overlay seeded with the same strain, whereas a bacteriocin will not produce a clearing zone when transferred to a fresh soft agar lawn, owing to the dilution of the bacteriocin. PMID:28117830

  12. Quantum-well states with image state character for Pb overlayers on Cu(111)

    NASA Astrophysics Data System (ADS)

    Zugarramurdi, A.; Zabala, N.; Silkin, V. M.; Chulkov, E. V.; Borisov, A. G.

    2012-08-01

    We study theoretically the quantum well states (QWSs) localized in Pb overlayers on Cu(111) surface. Particular emphasis is given to the states with energies close to the vacuum level. Inclusion of the long-range image potential tail into the model potential description of the system allows us to show the effect of hybridization between QWSs and image potential states (ISs). The particle-in-a-box energy sequence characteristic for QWSs evolves into the Rydberg series converging towards the vacuum level. The electron density of the corresponding states is partially moved from inside the metal overlayer into the vacuum. The decay rates due to the inelastic electron-electron scattering decrease with increasing energy, opposite to “conventional” QWSs and similar to the ISs. Many-body and wave packet propagation calculations of the inelastic decay rates are supplemented by simple analysis based on the phase accumulation model and wave-function penetration approximation. This allows an analytical description of the dependence of the QWS/ISs hybridization on different parameters and, in particular, on the overlayer thickness.

  13. Electronic structure of dense Pb overlayers on Si(111) investigated using angle-resolved photoemission

    NASA Astrophysics Data System (ADS)

    Choi, W. H.; Koh, H.; Rotenberg, E.; Yeom, H. W.

    2007-02-01

    Dense Pb overlayers on Si(111) are important as the wetting layer for anomalous Pb island growth as well as for their own complex “devil’s-staircase” phases. The electronic structures of dense Pb overlayers on Si(111) were investigated in detail by angle-resolved photoemission. Among the series of ordered phases found recently above one monolayer, the low-coverage 7×3 and the high-coverage 14×3 phases are studied; they are well ordered and form reproducibly in large areas. The band dispersions and Fermi surfaces of the two-dimensional (2D) electronic states of these overlayers are mapped out. A number of metallic surface-state bands are identified for both phases with complex Fermi contours. The basic features of the observed Fermi contours can be explained by overlapping 2D free-electron-like Fermi circles. This analysis reveals that the 2D electrons near the Fermi level of the 7×3 and 14×3 phases are mainly governed by strong 1×1 and 3×3 potentials, respectively. The origins of the 2D electronic states and their apparent Fermi surface shapes are discussed based on recent structure models.

  14. Image overlay solution based on threshold detection for a compact near infrared fluorescence goggle system

    PubMed Central

    Gao, Shengkui; Mondal, Suman B.; Zhu, Nan; Liang, RongGuang; Achilefu, Samuel; Gruev, Viktor

    2015-01-01

    Abstract. Near infrared (NIR) fluorescence imaging has shown great potential for various clinical procedures, including intraoperative image guidance. However, existing NIR fluorescence imaging systems either have a large footprint or are handheld, which limits their usage in intraoperative applications. We present a compact NIR fluorescence imaging system (NFIS) with an image overlay solution based on threshold detection, which can be easily integrated with a goggle display system for intraoperative guidance. The proposed NFIS achieves compactness, light weight, hands-free operation, high-precision superimposition, and a real-time frame rate. In addition, the miniature and ultra-lightweight light-emitting diode tracking pod is easy to incorporate with NIR fluorescence imaging. Based on experimental evaluation, the proposed NFIS solution has a lower detection limit of 25 nM of indocyanine green at 27 fps and realizes a highly precise image overlay of NIR and visible images of mice in vivo. The overlay error is limited within a 2-mm scale at a 65-cm working distance, which is highly reliable for clinical study and surgical use. PMID:25607724

  15. Iron aluminide weld overlay coatings for boiler tube protection in coal-fired low NOx boilers

    SciTech Connect

    Banovic, S.W.; DuPont, J.N.; Marder, A.R.

    1997-12-01

    Iron aluminide weld overlay coatings are currently being considered for enhanced sulfidation resistance in coal-fired low NO{sub x} boilers. The use of these materials is currently limited due to hydrogen cracking susceptibility, which generally increases with an increase in aluminum concentration of the deposit. The overall objective of this program is to attain an optimum aluminum content with good weldability and improved sulfidation resistance with respect to conventional materials presently in use. Research has been initiated using Gas Tungsten Arc Welding (GTAW) in order to achieve this end. Under different sets of GTAW parameters (wire feed speed, current), both single and multiple pass overlays were produced. Characterization of all weldments was conducted using light optical microscopy, scanning electron microscopy, and electron probe microanalysis. Resultant deposits exhibited a wide range of aluminum contents (5--43 wt%). It was found that the GTAW overlays with aluminum contents above {approximately}10 wt% resulted in cracked coatings. Preliminary corrosion experiments of 5 to 10 wt% Al cast alloys in relatively simple H{sub 2}/H{sub 2}S gas mixtures exhibited corrosion rates lower than 304 stainless steel.

  16. Energy Efficiency in MIMO Underlay and Overlay Device-to-Device Communications and Cognitive Radio Systems

    NASA Astrophysics Data System (ADS)

    Zappone, Alessio; Matthiesen, Bho; Jorswieck, Eduard Axel

    2017-02-01

    This paper addresses the problem of resource allocation for systems in which a primary and a secondary link share the available spectrum by an underlay or overlay approach. After observing that such a scenario models both cognitive radio and D2D communications, we formulate the problem as the maximization of the secondary energy efficiency subject to a minimum rate requirement for the primary user. This leads to challenging non-convex, fractional problems. In the underlay scenario, we obtain the global solution by means of a suitable reformulation. In the overlay scenario, two algorithms are proposed. The first one yields a resource allocation fulfilling the first-order optimality conditions of the resource allocation problem, by solving a sequence of easier fractional problems. The second one enjoys a weaker optimality claim, but an even lower computational complexity. Numerical results demonstrate the merits of the proposed algorithms both in terms of energy-efficient performance and complexity, also showing that the two proposed algorithms for the overlay scenario perform very similarly, despite the different complexity.

  17. Use of the Soft-agar Overlay Technique to Screen for Bacterially Produced Inhibitory Compounds.

    PubMed

    Hockett, Kevin L; Baltrus, David A

    2017-01-14

    The soft-agar overlay technique was originally developed over 70 years ago and has been widely used in several areas of microbiological research, including work with bacteriophages and bacteriocins, proteinaceous antibacterial agents. This approach is relatively inexpensive, with minimal resource requirements. This technique consists of spotting supernatant from a donor strain (potentially harboring a toxic compound(s)) onto a solidified soft agar overlay that is seeded with a bacterial test strain (potentially sensitive to the toxic compound(s)). We utilized this technique to screen a library of Pseudomonas syringae strains for intraspecific killing. By combining this approach with a precipitation step and targeted gene deletions, multiple toxic compounds produced by the same strain can be differentiated. The two antagonistic agents commonly recovered using this technique are bacteriophages and bacteriocins. These two agents can be differentiated using two simple additional tests. Performing a serial dilution on a supernatant containing bacteriophage will result in individual plaques becoming less in number with greater dilution, whereas serial dilution of a supernatant containing bacteriocin will result a clearing zone that becomes uniformly more turbid with greater dilution. Additionally, a bacteriophage will produce a clearing zone when spotted onto a fresh soft agar overlay seeded with the same strain, whereas a bacteriocin will not produce a clearing zone when transferred to a fresh soft agar lawn, owing to the dilution of the bacteriocin.

  18. Sub-40nm high-volume manufacturing overlay uncorrectable error evaluation

    NASA Astrophysics Data System (ADS)

    Baluswamy, Pary; Khurana, Ranjan; Orf, Bryan; Keller, Wolfgang

    2013-04-01

    Circuit layout and design rules have continued to shrink to the point where a few nanometers of pattern misalignment can negatively impact process capability and device yields. As wafer processes and film stacks have become more complex, overlay and alignment performance in high-volume manufacturing (HVM) have become increasingly sensitive to process and tool variations experienced by incoming wafers. Current HVM relies on overlay control via advanced process control (APC) feedback, single-exposure tool grid stability, scanner-to-scanner matching, correction models, sampling strategies, overlay mark design, and metrology. However, even with improvements to those methods, a large fraction of the uncorrectable errors (i.e., residuals) still remains. While lower residuals typically lead to increased yield performance, it is difficult to achieve in HVM due to the large combinations of wafer history in terms of prior tools, recipes, and ongoing process conversions. Hence, it is critical to understand the effect of residual errors on measurement sampling and model parameters to enable process control. In this study, we investigate the following: residual errors of sub-40nm processes as a function of correction models, sensitivity of the model parameters to residue, and the impact of data quality.

  19. Epicardial ablation guidance using coronary arterial models and live fluoroscopic overlay registrations

    NASA Astrophysics Data System (ADS)

    Manzke, R.; Thiagalingam, A.; Movassaghi, B.; d'Avila, A.; Reddy, V. Y.; Chan, R. C.

    2008-03-01

    Knowledge of patient-specific cardiac anatomy is required for catheter-based ablation in epicardial ablation procedures such as ventricular tachycardia (VT) ablation interventions. In particular, knowledge of critical structures such as the coronary arteries is essential to avoid collateral damage. In such ablation procedures, ablation catheters are brought in via minimally-invasive subxiphoid access. The catheter is then steered to ablation target sites on the left ventricle (LV). During the ablation and catheter navigation it is of vital importance to avoid damage of coronary structures. Contrast-enhanced rotational X-ray angiography of the coronary arteries delivers a 3D impression of the anatomy during the time of intervention. Vessel modeling techniques have been shown to be able to deliver accurate 3D anatomical models of the coronary arteries. To simplify epicardial navigation and ablation, we propose to overlay coronary arterial models, derived from rotational X-ray angiography and vessel modeling, onto real-time X-ray fluoroscopy. In a preclinical animal study, we show that overlay of intra-operatively acquired 3D arterial models onto X-ray helps to place ablation lesions at a safe distance from coronary structures. Example ablation lesions have been placed based on the model overlay at reasonable distances between key arterial vessels and on top of marginal branches.

  20. Cost-effective overlay and CD metrology on phase-shifting masks

    NASA Astrophysics Data System (ADS)

    McCallum, Martin; Smith, Stewart; Hourd, Andrew; Walton, Anthony J.; Stevenson, J. Tom M.

    2004-12-01

    This paper presents the use of specially designed electrically testable structures to measure characteristics of alternating aperture phase-shifting masks (altPSM). The linewidths of chrome features on the mask are measured using modified cross-bridge structures, the technique behind this is explained together with the specific designs used to characterise both dense and isolated features. A practical, manufacturable solution to overcoming the problem of the non-conductive anti-reflective chromium oxy-nitride is given and results shown to prove its success. Correlation to more conventional CD measurements reinforce this result. A new technique, to measure the overlay of the second laye, used in the mask manufacture as the mask for the quartz etch establishing the phase shifted areas, is discussed. This entails using capacitive test structures in a progressional offset array to establish the minimum capacitance, indicating the overlay achieved. This technique has the added advantage of removing the errors created by mask sag in overlay metrology tools where the mask is held only at the edge. Results are presented indicating the success of this technique.

  1. Structure of arginine overlayers at the aqueous gold interface: implications for nanoparticle assembly.

    PubMed

    Wright, Louise B; Merrill, Nicholas A; Knecht, Marc R; Walsh, Tiffany R

    2014-07-09

    Adsorption of small biomolecules onto the surface of nanoparticles offers a novel route to generation of nanoparticle assemblies with predictable architectures. Previously, ligand-exchange experiments on citrate-capped gold nanoparticles with the amino acid arginine were reported to support linear nanoparticle assemblies. Here, we use a combination of atomistic modeling with experimental characterization to explore aspects of the assembly hypothesis for these systems. Using molecular simulation, we probe the structural and energetic characteristics of arginine overlayers on the Au(111) surface under aqueous conditions at both low- and high-coverage regimes. In the low-density regime, the arginines lie flat on the surface. At constant composition, these overlayers are found to be lower in energy than the densely packed films, although the latter case appears kinetically stable when arginine is adsorbed via the zwitterion group, exposing the charged guanidinium group to the solvent. Our findings suggest that zwitterion-zwitterion hydrogen bonding at the gold surface and minimization of the electrostatic repulsion between adjacent guanidinium groups play key roles in determining arginine overlayer stability at the aqueous gold interface. Ligand-exchange experiments of citrate-capped gold nanoparticles with arginine derivatives agmatine and N-methyl-l-arginine reveal that modification at the guanidinium group significantly diminishes the propensity for linear assembly of the nanoparticles.

  2. Intra-field on-product overlay improvement by application of RegC and TWINSCAN corrections

    NASA Astrophysics Data System (ADS)

    Sharoni, Ofir; Dmitriev, Vladimir; Graitzer, Erez; Perets, Yuval; Gorhad, Kujan; van Haren, Richard; Cekli, Hakki E.; Mulkens, Jan

    2015-03-01

    The on product overlay specification and Advanced Process Control (APC) is getting extremely challenging particularly after the introduction of multi-patterning applications like Spacer Assisted Double Patterning (SADP) and multipatterning techniques like N-repetitive Litho-Etch steps (LEN, N >= 2). When the latter is considered, most of the intrafield overlay contributors drop out of the overlay budget. This is a direct consequence of the fact that the scanner settings (like dose, illumination settings, etc.) as well as the subsequent processing steps can be made very similar for two consecutive Litho-Etch layers. The major overlay contributor that may require additional attention is the Image Placement Error (IPE). When the inter-layer overlay is considered, controlling the intra-field overlay contribution gets more complicated. In addition to the IPE contribution, the TWINSCANTM lens fingerprint in combination with the exposure settings is going to play a role as well. Generally speaking, two subsequent functional layers have different exposure settings. This results in a (non-reticle) additional overlay contribution. In this paper, we have studied the wafer overlay correction capability by RegC® in addition to the TWINSCANTM intrafield corrections to improve the on product overlay performance. RegC® is a reticle intra-volume laser writing technique that causes a predictable deformation element (RegC® deformation element) inside the quartz (Qz) material of a reticle. This technique enables to post-process an existing reticle to correct for instance for IPE. Alternatively, a pre-determined intra-field fingerprint can be added to the reticle such that it results in a straight field after exposure. This second application might be very powerful to correct for instance for (cold) lens fingerprints that cannot be corrected by the scanner itself. Another possible application is the intra-field processing fingerprint. One should realize that a RegC® treatment of a

  3. Microbiologically induced deterioration of concrete - A Review

    PubMed Central

    Wei, Shiping; Jiang, Zhenglong; Liu, Hao; Zhou, Dongsheng; Sanchez-Silva, Mauricio

    2013-01-01

    Microbiologically induced deterioration (MID) causes corrosion of concrete by producing acids (including organic and inorganic acids) that degrade concrete components and thus compromise the integrity of sewer pipelines and other structures, creating significant problems worldwide. Understanding of the fundamental corrosion process and the causal agents will help us develop an appropriate strategy to minimize the costs in repairs. This review presents how microorganisms induce the deterioration of concrete, including the organisms involved and their colonization and succession on concrete, the microbial deterioration mechanism, the approaches of studying MID and safeguards against concrete biodeterioration. In addition, the uninvestigated research area of MID is also proposed. PMID:24688488

  4. Two-layer critical dimensions and overlay process window characterization and improvement in full-chip computational lithography

    NASA Astrophysics Data System (ADS)

    Sturtevant, John L.; Liubich, Vlad; Gupta, Rachit

    2016-04-01

    Edge placement error (EPE) was a term initially introduced to describe the difference between predicted pattern contour edge and the design target for a single design layer. Strictly speaking, this quantity is not directly measurable in the fab. What is of vital importance is the relative edge placement errors between different design layers, and in the era of multipatterning, the different constituent mask sublayers for a single design layer. The critical dimensions (CD) and overlay between two layers can be measured in the fab, and there has always been a strong emphasis on control of overlay between design layers. The progress in this realm has been remarkable, accelerated in part at least by the proliferation of multipatterning, which reduces the available overlay budget by introducing a coupling of overlay and CD errors for the target layer. Computational lithography makes possible the full-chip assessment of two-layer edge to edge distances and two-layer contact overlap area. We will investigate examples of via-metal model-based analysis of CD and overlay errors. We will investigate both single patterning and double patterning. For single patterning, we show the advantage of contour-to-contour simulation over contour to target simulation, and how the addition of aberrations in the optical models can provide a more realistic CD-overlay process window (PW) for edge placement errors. For double patterning, the interaction of 4-layer CD and overlay errors is very complex, but we illustrate that not only can full-chip verification identify potential two-layer hotspots, the optical proximity correction engine can act to mitigate such hotspots and enlarge the joint CD-overlay PW.

  5. Three-dimensional magnetic resonance imaging overlay to assist with percutaneous transhepatic access at the time of cardiac catheterization

    PubMed Central

    Whiteside, Wendy; Christensen, Jason; Zampi, Jeffrey D

    2015-01-01

    Multimodality image overlay is increasingly used for complex interventional procedures in the cardiac catheterization lab. We report a case in which three-dimensional magnetic resonance imaging (3D MRI) overlay onto live fluoroscopic imaging was utilized to safely obtain transhepatic access in a 12-year-old patient with prune belly syndrome, complex and distorted abdominal anatomy, and a vascular mass within the liver. PMID:26085770

  6. Estimation of Concrete's Porosity by Ultrasounds

    NASA Astrophysics Data System (ADS)

    Benouis, A.; Grini, A.

    Durability of concrete depends strongly on porosity; this conditions the intensity of the interactions of the concrete with the aggressive agents. The pores inside the concrete facilitate the process of damage, which is generally initiated on the surface. The most used measurement is undoubtedly the measurement of porosity accessible to water. The porosimetry by intrusion with mercury constitutes a tool for investigation of the mesoporosity. The relationship between concrete mixtures, porosity and ultrasonic velocity of concrete samples measured by ultrasonic NDT is investigated. This experimental study is interested in the relations between the ultrasonic velocity measured by transducers of 7.5 mm and 49.5 mm diameter and with 54 kHz frequency. Concrete specimens (160 mm diameter and 320 mm height) are fabricated with concrete of seven different mixtures (various W/C and S/S + G ratios), which gave porosities varying between 7% and 16%. Ultrasonic velocities in concrete were measured in longitudinal direction. Finally the results showed the influence of ratio W/C, where the porosity of the concretes of a ratio W/C _0,5 have correctly estimated by ultrasonic velocity. The integration of the concretes of a lower ratio, in this relation, caused a great dispersion. Porosity estimation of concretes with a ratio W/C lower than 0,5 became specific to each ratio.

  7. Diffusion of Radionuclides in Concrete and Soil

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Bovaird, Chase C.; Parker, Kent E.; Recknagle, Kurtis P.; Clayton, Libby N.; Wood, Marcus I.

    2012-04-25

    One of the methods being considered for safely disposing of Category 3 low-level radioactive wastes is to encase the waste in concrete. Such concrete encasement would contain and isolate the waste packages from the hydrologic environment and would act as an intrusion barrier. Any failure of concrete encasement may result in water intrusion and consequent mobilization of radionuclides from the waste packages. The mobilized radionuclides may escape from the encased concrete by mass flow and/or diffusion and move into the surrounding subsurface environment. Therefore, it is necessary to assess the performance of the concrete encasement structure and the ability of the surrounding soil to retard radionuclide migration. The objective of our study was to measure the diffusivity of Re, Tc and I in concrete containment and the surrounding vadose zone soil. Effects of carbonation, presence of metallic iron, and fracturing of concrete and the varying moisture contents in soil on the diffusivities of Tc and I were evaluated.

  8. Durable fiber reinforced self-compacting concrete

    SciTech Connect

    Corinaldesi, V.; Moriconi, G

    2004-02-01

    In order to produce thin precast elements, a self-compacting concrete was prepared. When manufacturing these elements, homogenously dispersed steel fibers instead of ordinary steel-reinforcing mesh were added to the concrete mixture at a dosage of 10% by mass of cement. An adequate concrete strength class was achieved with a water to cement ratio of 0.40. Compression and flexure tests were carried out to assess the safety of these thin concrete elements. Moreover, serviceability aspects were taken into consideration. Firstly, drying shrinkage tests were carried out in order to evaluate the contribution of steel fibers in counteracting the high concrete strains due to a low aggregate-cement ratio. Secondly, the resistance to freezing and thawing cycles was investigated on concrete specimens in some cases superficially treated with a hydrophobic agent. Lastly, both carbonation and chloride penetration tests were carried out to assess durability behavior of this concrete mixture.

  9. Advanced overlay: sampling and modeling for optimized run-to-run control

    NASA Astrophysics Data System (ADS)

    Subramany, Lokesh; Chung, WoongJae; Samudrala, Pavan; Gao, Haiyong; Aung, Nyan; Gomez, Juan Manuel; Gutjahr, Karsten; Park, DongSuk; Snow, Patrick; Garcia-Medina, Miguel; Yap, Lipkong; Demirer, Onur Nihat; Pierson, Bill; Robinson, John C.

    2016-03-01

    In recent years overlay (OVL) control schemes have become more complicated in order to meet the ever shrinking margins of advanced technology nodes. As a result, this brings up new challenges to be addressed for effective run-to- run OVL control. This work addresses two of these challenges by new advanced analysis techniques: (1) sampling optimization for run-to-run control and (2) bias-variance tradeoff in modeling. The first challenge in a high order OVL control strategy is to optimize the number of measurements and the locations on the wafer, so that the "sample plan" of measurements provides high quality information about the OVL signature on the wafer with acceptable metrology throughput. We solve this tradeoff between accuracy and throughput by using a smart sampling scheme which utilizes various design-based and data-based metrics to increase model accuracy and reduce model uncertainty while avoiding wafer to wafer and within wafer measurement noise caused by metrology, scanner or process. This sort of sampling scheme, combined with an advanced field by field extrapolated modeling algorithm helps to maximize model stability and minimize on product overlay (OPO). Second, the use of higher order overlay models means more degrees of freedom, which enables increased capability to correct for complicated overlay signatures, but also increases sensitivity to process or metrology induced noise. This is also known as the bias-variance trade-off. A high order model that minimizes the bias between the modeled and raw overlay signature on a single wafer will also have a higher variation from wafer to wafer or lot to lot, that is unless an advanced modeling approach is used. In this paper, we characterize the bias-variance trade off to find the optimal scheme. The sampling and modeling solutions proposed in this study are validated by advanced process control (APC) simulations to estimate run-to-run performance, lot-to-lot and wafer-to- wafer model term monitoring to

  10. Effect of silica overlayers on laser damage of HfO2-SiO2 56 degrees incidence high reflectors

    NASA Astrophysics Data System (ADS)

    Walton, Christopher C.; Genin, Francois Y.; Chow, Robert; Kozlowski, Mark R.; Loomis, Gary E.; Pierce, Edward L.

    1996-05-01

    A series of hafnia/silica, oblique incidence (56 degree(s)), 1064 nm high reflectors (HRs) were prepared and coated with silica overlayers of varying optical thickness from (lambda) /2 to 4(lambda) in order to determine the effect of an overlayer on the laser-damage resistance of the HRs. The stress and laser damage thresholds for S and P polarization of the HRs were measured, and the damage sites for P polarization examined by Atomic Force Microscopy. All the multilayers were found to be in compression, with an intrinsic stress increasing with overlayer thickness. The presence of an overlayer and its thickness did not affect the damage threshold significantly. However, the presence of an overlayer greatly influenced the size and morphology of the damage. First, the overlayer prevented catastrophic `burns' of the hafnia top layer. Second, as the overlayer thickness increased, two distinct damage morphologies were found: jagged pits and round craters. The diameter of these pits and craters then increased somewhat with thicker overlayers. The depths of the pits and craters also increased with overlayer thickness, and the depths showed failure occurring at the interfaces below the hafnia layers. The side-wall angles of the craters were shallower with thicker overlayers, but there was no angle dependence for the pits. The craters showed fracture-like features and a small hillock or pit on their bottom surfaces. No correlation of damage morphology to conditioning or fluence was found.

  11. IMPERMEABLE THIN Al{sub 2}O{sub 3} OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

    SciTech Connect

    Scott X. Mao

    2004-06-30

    In order to further improve the hot corrosion resistance of yttria-stabilized zirconia (YSZ), an Al{sub 2}O{sub 3} overlay of 58 {micro}m thick was deposited on the surface of YSZ by electron-beam physical vapor deposition. Hot corrosion tests were performed on the YSZ coatings with {gamma}-Al{sub 2}O{sub 3} overlay and {alpha}-Al{sub 2}O{sub 3} overlay in molten salt mixture (Na2SO4 + 5wt%V2O5) at 950 C. The {alpha}-Al{sub 2}O{sub 3} overlay was obtained by the post-annealing of g-Al{sub 2}O{sub 3} overlay at 1200 C for 1h. The results showed that compared with the hot corrosion resistance of YSZ coating with 25 {micro}m thick {gamma}-Al{sub 2}O{sub 3} overlay, either thickening {gamma}-Al{sub 2}O{sub 3} overlay or employing {alpha}-Al{sub 2}O{sub 3} overlay could impair the hot corrosion resistance of YSZ coating, because the tensile stresses developed in the alumina overlay in both cases due to the mismatch in thermal expansion coefficient (TEC) between alumina and zirconia resulted in cracking of Al{sub 2}O{sub 3} overlay. The formation of cracks increased contact area between molten salt and Al{sub 2}O{sub 3} overlay, and also the penetration rate of molten salt into Al{sub 2}O{sub 3} overlay and YSZ coating, leading a faster and greater degradation of YSZ coating upon exposure. In the next reporting period, we will study the effect of Al{sub 2}O{sub 3} overlay thickness on hot corrosion and spalling of YSZ coatings.

  12. Radionuclide Retention in Concrete Wasteforms

    SciTech Connect

    Bovaird, Chase C.; Jansik, Danielle P.; Wellman, Dawn M.; Wood, Marcus I.

    2011-09-30

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. The information present in the report provides data that (1) measures the effect of concrete wasteform properties likely to influence radionuclide migration; and (2) quantifies the rate of carbonation of concrete materials in a simulated vadose zone repository.

  13. Laser ablation studies of concrete

    SciTech Connect

    Savina, M.; Xu, Z.; Wang, Y.; Reed, C.; Pellin, M.

    1999-10-20

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.

  14. Clogging in permeable concrete: A review.

    PubMed

    Kia, Alalea; Wong, Hong S; Cheeseman, Christopher R

    2017-05-15

    Permeable concrete (or "pervious concrete" in North America) is used to reduce local flooding in urban areas and is an important sustainable urban drainage system. However, permeable concrete exhibits reduction in permeability due to clogging by particulates, which severely limits service life. This paper reviews the clogging mechanism and current mitigating strategies in order to inform future research needs. The pore structure of permeable concrete and characteristics of flowing particulates influence clogging, which occurs when particles build-up and block connected porosity. Permeable concrete requires regular maintenance by vacuum sweeping and pressure washing, but the effectiveness and viability of these methods is questionable. The potential for clogging is related to the tortuosity of the connected porosity, with greater tortuosity resulting in increased potential for clogging. Research is required to develop permeable concrete that can be poured on-site, which produces a pore structure with significantly reduced tortuosity.

  15. A Production Proven Technique For Machine-To-Machine Overlay Matching

    NASA Astrophysics Data System (ADS)

    Cummings, Michael J.; Haley, Norman; Ngo, Ken; Schaller, John

    1989-01-01

    The natural progression of today's semiconductor industry is toward smaller device features and tighter registration requirements. Typically, this progression results in high capital equipment investments, along with a large capacity reduction per investment dollar for most lithographic exposure processes. One major cause for the capacity loss is the industry's willingness to migrate from full-field scanning projection printers to a lower throughput field-by-field alignment step-and-repeat exposure system. Standard Microsystems Corporation (SMC) sought to achieve higher performance on its scanners without compromising throughput. The original goal at SMC was to improve Perkin-Elmer's specified Micralign 641 HT machine-to-machine registration performance from ± 0.30 micron to less than ± 0.25 micron. With this in mind, we set out to investigate the true alignment and registration limitations of a Micralign Model 600 HT Series Projection Aligner. Although SMC was apparently successful at matching two Micralign 641 HT systems to ± 0.25 micron by manually reading verniers, this technique proved to be time consuming and prone to human error. Electrical probing of wafers was considered, but the special masks and processing steps and its destructive nature were considered undesirable. For this study, an automatic optical overlay measurement system was used to optimize overlay on the SMC Micralign systems. The results were enlightening. The specified overlay of ± 0.30 micron for 98% of the data improved to better than ± 0.25 micron, 3 sigma. These results were achieved without the use of Automatic Magnification Compensation (AVM/AMC). We.also discovered that many otherwise transparent mechanical/optical anomalies, such as contamination and scan interference, could be readily identified. Experimental data is presented and the beneficial application of this technique to a production process is discussed.

  16. A Production Proven Technique For Machine-To-Machine Overlay Matching

    NASA Astrophysics Data System (ADS)

    Cummings, Michael J.; Haley, Norman J.; Ngo, Ken T.; Schaller, John W.

    1989-07-01

    The natural progression of today's semiconductor industry is toward smaller geometric features and registration requirements. Typically, this progression results in high capital equipment investments, along with a large capacity reduction per investment dollar for most lithographic exposure processes. One major cause for the capacity loss is the industry's willingness to migrate from full-field scanning projection printers to a lower throughput field-by-field alignment step-and-repeat exposure system. Standard Microsystems Corporation (SMC) sought to achieve higher performance on its scanners without compromising throughput. The original goal at SMC was to improve Perkin-Elmer's Micralign 641 HT machine-to-machine registration specification of ± 0.30 micron to less than ± 0.25 micron. With this in mind, we set out to investigate the true alignment and registration limitations of a Micralign Model 600 HT Series Projection Aligner. Although SMC was apparently successful at matching two Micralign 641 HT systems to ± 0.25 micron by manually reading verniers, this technique proved to be time consuming and prone to human error. Electrical probing of wafers was considered, but the special masks and processing steps and its destructive nature were considered undesirable. For this study, an automatic optical overlay measurement system was used to optimize overlay on the SMC Micralign systems. The results were enlightening. The specified overlay of ± 0.30 micron for 98% of the data improved to better than ± 0.25 micron, 3 sigma. These results were achieved without the use of Automatic Magnification Compensation (AVM/AMC). We also discovered that many otherwise transparent mechanical/optical anomalies, such as contamination and scan interference, could be readily identified. Experimental data is presented and the beneficial application of this technique to a production process is discussed.

  17. Adaptive on-line estimation and control of overlay tool bias

    NASA Astrophysics Data System (ADS)

    Martinez, Victor M.; Finn, Karen; Edgar, Thomas F.

    2003-06-01

    Modern lithographic manufacturing processes rely on various types of exposure tools, used in a mix-and-match fashion. The motivation to use older tools alongside state-of-the-art tools is lower cost and one of the tradeoffs is a degradation in overlay performance. While average prices of semiconductor products continue to fall, the cost of manufacturing equipment rises with every product generation. Lithography processing, including the cost of ownership for tools, accounts for roughly 30% of the wafer processing costs, thus the importance of mix-and-match strategies. Exponentially Weighted Moving Average (EWMA) run-by-run controllers are widely used in the semiconductor manufacturing industry. This type of controller has been implemented successfully in volume manufacturing, improving Cpk values dramatically in processes like photolithography and chemical mechanical planarization. This simple, but powerful control scheme is well suited for adding corrections to compensate for Overlay Tool Bias (OTB). We have developed an adaptive estimation technique to compensate for overlay variability due to differences in the processing tools. The OTB can be dynamically calculated for each tool, based on the most recent measurements available, and used to correct the control variables. One approach to tracking the effect of different tools is adaptive modeling and control. The basic premise of an adaptive system is to change or adapt the controller as the operating conditions of the system change. Using closed-loop data, the adaptive control algorithm estimates the controller parameters using a recursive estimation technique. Once an updated model of the system is available, modelbased control becomes feasible. In the simplest scenario, the control law can be reformulated to include the current state of the tool (or its estimate) to compensate dynamically for OTB. We have performed simulation studies to predict the impact of deploying this strategy in production. The results

  18. Does Concrete Self-Decontaminate VX

    DTIC Science & Technology

    2003-07-01

    DOES CONCRETE SELF-DECONTAMINATE VX? George W. Wagner, Richard J. O’Connor, and Lawrence R. Procell U.S. Army Edgewood Chemical ...this method avoids the problem of tenuous extraction procedures. In a recently published paper, Groenewold et al.2 examined the fate of dilute VX...concrete employed by Groenewold et al.,2 the current study examines VX droplets on the order of several µL to determine the behavior of VX on concrete in

  19. Phase 2 microwave concrete decontamination results

    SciTech Connect

    White, T.L.; Foster, D. Jr.; Wilson, C.T.; Schaich, C.R.

    1995-04-01

    The authors report on the results of the second phase of a four-phase program at Oak Ridge National Laboratory to develop a system to decontaminate concrete using microwave energy. The microwave energy is directed at the concrete surface through the use of an optimized wave guide antenna, or applicator, and this energy rapidly heats the free water present in the interstitial spaces of the concrete matrix. The resulting steam pressure causes the surface to burst in much the same way popcorn pops in a home microwave oven. Each steam explosion removes several square centimeters of concrete surface that are collected by a highly integrated wave guide and vacuum system. The authors call this process the microwave concrete decontamination, or MCD, process. In the first phase of the program the principle of microwaves concrete removal concrete surfaces was demonstrated. In these experiments, concrete slabs were placed on a translator and moved beneath a stationary microwave system. The second phase demonstrated the ability to mobilize the technology to remove the surfaces from concrete floors. Area and volume concrete removal rates of 10.4 cm{sup 2}/s and 4.9 cm{sup 3}/S, respectively, at 18 GHz were demonstrated. These rates are more than double those obtained in Phase 1 of the program. Deeper contamination can be removed by using a longer residence time under the applicator to create multiple explosions in the same area or by taking multiple passes over previously removed areas. Both techniques have been successfully demonstrated. Small test sections of painted and oil-soaked concrete have also been removed in a single pass. Concrete with embedded metal anchors on the surface has also been removed, although with some increased variability of removal depth. Microwave leakage should not pose any operational hazard to personnel, since the observed leakage was much less than the regulatory standard.

  20. Radiation shielding concrete made of Basalt aggregates.

    PubMed

    Alhajali, S; Yousef, S; Kanbour, M; Naoum, B

    2013-04-01

    In spite of the fact that Basalt is a widespread type of rock, there is very little available information on using it as aggregates for concrete radiation shielding. This paper investigates the possibility of using Basalt for the aforementioned purpose. The results have shown that Basalt could be used successfully for preparing radiation shielding concrete, but some attention should be paid to the choice of the suitable types of Basalt and for the neutron activation problem that could arise in the concrete shield.

  1. Laboratory Characterization of Gray Masonry Concrete

    DTIC Science & Technology

    2007-08-01

    ER D C/ G SL T R- 07 -2 3 Laboratory Characterization of Gray Masonry Concrete Erin M. Williams, Stephen A. Akers, and Paul A. Reed...07-23 August 2007 Laboratory Characterization of Gray Masonry Concrete Erin M. Williams, Stephen A. Akers, and Paul A. Reed Geotechnical and...constitutive property behavior of a gray masonry concrete . A total of 38 mechanical property tests were successfully completed: two hydrostatic

  2. Polypropylene Fibers in Portland Cement Concrete Pavements.

    DTIC Science & Technology

    1992-08-01

    Bibliography on Fiber- Reinforced Cement and Concrete," Miscellaneous Paper C-76-6, with supplements 1, 2, 3, and 4 ( 1977 , 1979, 1980, and 1982), US Army... Mindess , S., Bentur, A., Yan, C., and Vondran, G., "Impact Resistance of Concrete Containing Both Conventional Steel Reinforcement and Fibrillated...Roads, Streets, Walks, and Open Storage Areas," TM 5-822-6/AFM 88-7, Chap. 7, Washington, DC, 1977 . 18. __ , "Concrete Floor Slabs on Grade Subjected

  3. Modeling degradation and failure of Ni-Cr-Al overlay coatings

    NASA Technical Reports Server (NTRS)

    Nesbitt, J. A.; Heckel, R. W.

    1984-01-01

    Degradation of a Ni-16Cr-25Al-0.06Zr overlay coating on a Ni-22Cr substrate was examined after oxidation accompanied by thermal cycling. Concentration/distance profiles were measured in the coating and substrate after various one-hour cycles at 1150 C. A numerical model was developed to simulate coating degradation by simultaneous oxidation and coating/substrate interdiffusion. The validity of the model was confirmed by comparison of predicted and measured concentration/distance profiles. The ability of the model to identify critical system parameters was demonstrated for the case of the initial Al and Cr content of the coating and substrate.

  4. Robotic weld overlay coatings for erosion control. Quarterly technical progress report, April 1993--June 1993

    SciTech Connect

    Levin, B.F.; Dupont, J.N.; Marder, A.R.

    1993-07-20

    Twelve weld overlay hardfacing alloys have been selected for preliminary erosion testing based upon a literature review. Four of the selected coatings were deposited on a 1018 steel substrate using plasma arc welding process. During the past quarter, the remaining eight coatings were deposited in the same manner. Ten samples from each coatings were prepared for erosion testing. Microstructural characterization of each coating is in progress. This progress report describes coating deposition and sample preparation procedures. Relation between coatings hardness and formation of cracks in coatings is discussed.

  5. The promotion of CO dissociation by molybdenum oxide overlayers on rhodium

    NASA Astrophysics Data System (ADS)

    Szenti, Imre; Bugyi, László; Kónya, Zoltán

    2017-03-01

    A considerable promotional effect of MoOx species observed at high pressures on the catalytic activity of rhodium initiated the present UHV model study. The MoOx overlayers formed on Rh films (0.15-20.0 ML) supported by TiO2(110) substrate were characterized by AES, TPD, work function (WF) measurements and CO adsorption. On the mixed oxide support produced by depositing 1.2 ML Mo onto TiO2(110), a new recombinative CO desorption state was observed with Tp=700 K, assigned as β-CO and related to the promotional effect of MoOx species diffused onto Rh particles of 1.0 ML coverage. The development of β-CO needs 0.5-0.7 ML threshold Rh coverage, attributable to particle size effect and geometric factors governing the CO adsorption. The β-CO state with Tp=725-742 K could also be detected on Rh films covered by MoOx moiety formed by the oxidation of Mo overlayers in O2. Remarkably, recombinative CO desorption with Tp=700 K could be observed on the Rh nanoparticles covered by MoOzCy produced from pure Mo deposits by CO adsorption, too. In harmony with the promotional effect of MoOx overlayer found at high pressures, it is established that the dissociation of CO is maximal at 0.2-0.3 ML Mo coverage, attributed to the presence of active sites at the oxide-metal interface. The low desorption peak temperature (700 K) of associative CO desorption observed in the presence of MoOx and MoOzCy overlayers indicates a low activation energy for the reactions of Oa and Ca atoms, allowing high reaction rates for these intermediates. The MoOx species exerted both promotion and inhibition effects on CO adsorption at sub-monolayer coverages, but above 1 ML it completely suppressed the reactivity of rhodium layers towards CO, suggesting that its surface concentration is a critical factor.

  6. Economic analysis of recycling contaminated concrete

    SciTech Connect

    Stephen, A.; Ayers, K.W.; Boren, J.K.; Parker, F.L.

    1997-02-01

    Decontamination and Decommissioning activities in the DOE complex generate large volumes of radioactively contaminated and uncontaminated concrete. Currently, this concrete is usually decontaminated, the contaminated waste is disposed of in a LLW facility and the decontaminated concrete is placed in C&D landfills. A number of alternatives to this practice are available including recycling of the concrete. Cost estimates for six alternatives were developed using a spreadsheet model. The results of this analysis show that recycling alternatives are at least as economical as current practice.

  7. Experimental needs of high temperature concrete

    SciTech Connect

    Chern, J.C.; Marchertas, A.H.

    1985-01-01

    The needs of experimental data on concrete structures under high temperature, ranging up to about 370/sup 0/C for operating reactor conditions and to about 900/sup 0/C and beyond for hypothetical accident conditions, are described. This information is required to supplement analytical methods which are being implemented into the finite element code TEMP-STRESS to treat reinforced concrete structures. Recommended research ranges from material properties of reinforced/prestressed concrete, direct testing of analytical models used in the computer codes, to investigations of certain aspects of concrete behavior, the phenomenology of which is not well understood. 10 refs.

  8. Seismic behavior of lightweight concrete columns

    NASA Astrophysics Data System (ADS)

    Rabbat, B. G.; Daniel, J. I.; Weinmann, T. L.; Hanson, N. W.

    1982-09-01

    Sixteen full-scale, column-beam assemblies, which represented a portion of a frame subjected to simulated seismic loading, were tested. Controlled test parameters included concrete type, column size, amount of main column steel, size and spacing of column confining hoops, and magnitude of column axial load. The columns were subjected to constant axial load and slow moment reversals at increasing inelastic deformations. Test data showed that properly designed lightweight concrete columns maintained ductility and strength when subjected to large inelastic deformations from load reversals. Confinement requirements for normal weight concrete columns were shown to be applicable to lightweight concrete columns up to thirty percent of the design strength.

  9. Pentek concrete scabbling system: Baseline report; Summary

    SciTech Connect

    1997-07-31

    The Pentek concrete scabbling system consists of the MOOSE{reg_sign} scabbler, the SQUIRREL{reg_sign}-I and SQUIRREL{reg_sign}-III scabblers, and VAC-PAC. The scabblers are designed to scarify concrete floors and slabs using cross section, tungsten carbide tipped bits. The bits are designed to remove concrete in 3/8 inch increments. The bits are either 9-tooth or demolition type. The scabblers are used with a vacuum system designed to collect and filter the concrete dust and contamination that is removed from the surface. The safety and health evaluation during the human factors assessment focused on two main areas: noise and dust.

  10. Proceedings of the concrete decontamination workshop

    SciTech Connect

    Halter, J.M.; Sullivan, R.G.; Currier, A.J.

    1980-05-28

    Fourteen papers were presented. These papers describe concrete surface removal methods and equipment, as well as experiences in decontaminating and removing both power and experimental nuclear reactors.

  11. Use of Hydrogen Chemisorption and Ethylene Hydrogenation as Predictors for Aqueous Phase Reforming of Lactose over Ni@Pt and Co@Pt Bimetallic Overlayer Catalysts

    SciTech Connect

    Lai, Qinghua; Skoglund, Michael D.; Zhang, Chen; Morris, Allen R.; Holles, Joseph H.

    2016-10-20

    Overlayer Pt on Ni (Ni@Pt) or Co (Co@Pt) were synthesized and tested for H2 generation from APR of lactose. H2 chemisorption descriptor showed that Ni@Pt and Co@Pt overlayer catalysts had reduced H2 adsorption strength compared to a Pt only catalyst, which agree with computational predictions. The overlayer catalysts also demonstrated lower activity for ethylene hydrogenation than the Pt only catalyst, which likely resulted from decreased H2 binding strength decreasing the surface coverage of H2. XAS results showed that overlayer catalysts exhibited higher white line intensity than the Pt catalyst, which indicates a negative d-band shift for the Pt overlayer, further providing evidence for overlayer formation. Lactose APR studies showed that lactose can be used as feedstock to produce H2 and CO under desirable reaction conditions. The Pt active sites of Ni@Pt and Co@Pt overlayer catalysts showed significantly enhanced H2 production selectivity and activity when compared with that of a Pt only catalyst. The single deposition overlayer with the largest d-band shift showed the highest H2 activity. The results suggest that overlayer formation using directed deposition technique could modify the behavior of the surface metal and ultimately modify the APR activity.

  12. Assessment of potential location of high arsenic contamination using fuzzy overlay and spatial anisotropy approach in iron mine surrounding area.

    PubMed

    Weerasiri, Thanes; Wirojanagud, Wanpen; Srisatit, Thares

    2014-01-01

    Fuzzy overlay approach on three raster maps including land slope, soil type, and distance to stream can be used to identify the most potential locations of high arsenic contamination in soils. Verification of high arsenic contamination was made by collection samples and analysis of arsenic content and interpolation surface by spatial anisotropic method. A total of 51 soil samples were collected at the potential contaminated location clarified by fuzzy overlay approach. At each location, soil samples were taken at the depth of 0.00-1.00 m from the surface ground level. Interpolation surface of the analysed arsenic content using spatial anisotropic would verify the potential arsenic contamination location obtained from fuzzy overlay outputs. Both outputs of the spatial surface anisotropic and the fuzzy overlay mapping were significantly spatially conformed. Three contaminated areas with arsenic concentrations of 7.19 ± 2.86, 6.60 ± 3.04, and 4.90 ± 2.67 mg/kg exceeded the arsenic content of 3.9 mg/kg, the maximum concentration level (MCL) for agricultural soils as designated by Office of National Environment Board of Thailand. It is concluded that fuzzy overlay mapping could be employed for identification of potential contamination area with the verification by surface anisotropic approach including intensive sampling and analysis of the substances of interest.

  13. A nanometric Rh overlayer on a metal foil surface as a highly efficient three-way catalyst

    PubMed Central

    Misumi, Satoshi; Yoshida, Hiroshi; Hinokuma, Satoshi; Sato, Tetsuya; Machida, Masato

    2016-01-01

    Pulsed arc-plasma (AP) deposition of an Rh overlayer on an Fe–Cr–Al stainless steel foil produced a composite material that exhibited high activity for automotive three-way catalysis (TWC). The AP pulses deposited metallic Rh nanoparticles 1–3 nm in size, whose density on the surface increased with the number of pulses. This led to coalescence and grain growth on the foil surface and the eventual formation of a uniform two-dimensional Rh overlayer. Full coverage of the 51 μm-thick flat foil by a 3.2 nm-thick Rh overlayer was achieved after 1,000 pulses. A simulated TWC reaction using a miniature honeycomb fabricated using flat and corrugated foils with the Rh overlayers exhibited successful light-off at a practical gaseous hourly space velocity of 1.2 × 105 h−1. The turnover frequency for the NO–CO reaction over the metallic honeycomb catalyst was ca. 80-fold greater than that achieved with a reference Rh/ZrO2-coated cordierite honeycomb prepared using a conventional wet impregnation and slurry coating procedure. Despite the nonporosity and low surface area of the foil-supported Rh overlayer compared with conventional powder catalysts (Rh/ZrO2), it is a promising alternative design for more efficient automotive catalysts that use less Rh loading. PMID:27388976

  14. A nanometric Rh overlayer on a metal foil surface as a highly efficient three-way catalyst.

    PubMed

    Misumi, Satoshi; Yoshida, Hiroshi; Hinokuma, Satoshi; Sato, Tetsuya; Machida, Masato

    2016-07-08

    Pulsed arc-plasma (AP) deposition of an Rh overlayer on an Fe-Cr-Al stainless steel foil produced a composite material that exhibited high activity for automotive three-way catalysis (TWC). The AP pulses deposited metallic Rh nanoparticles 1-3 nm in size, whose density on the surface increased with the number of pulses. This led to coalescence and grain growth on the foil surface and the eventual formation of a uniform two-dimensional Rh overlayer. Full coverage of the 51 μm-thick flat foil by a 3.2 nm-thick Rh overlayer was achieved after 1,000 pulses. A simulated TWC reaction using a miniature honeycomb fabricated using flat and corrugated foils with the Rh overlayers exhibited successful light-off at a practical gaseous hourly space velocity of 1.2 × 10(5) h(-1). The turnover frequency for the NO-CO reaction over the metallic honeycomb catalyst was ca. 80-fold greater than that achieved with a reference Rh/ZrO2-coated cordierite honeycomb prepared using a conventional wet impregnation and slurry coating procedure. Despite the nonporosity and low surface area of the foil-supported Rh overlayer compared with conventional powder catalysts (Rh/ZrO2), it is a promising alternative design for more efficient automotive catalysts that use less Rh loading.

  15. IMPERMEABLE THIN Al2O3 OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

    SciTech Connect

    Scott X. Mao

    2003-06-10

    In order to improve the hot corrosion resistance of yttria-stabilized zirconia (YSZ), an Al{sub 2}O{sub 3} overlay has been deposited on the surface of YSZ by electron-beam physical vapor deposition. Currently, hot corrosion tests were performed on the YSZ coatings with and without Al{sub 2}O{sub 3} overlay in molten salt mixture (Na{sub 2}SO{sub 4} + 0 {approx} 15wt%V{sub 2}O{sub 5}) at 950 C in order to investigate the effect of amount of vanadate on the hot corrosion behaviors. The results showed that the presence of in V{sub 2}O{sub 5} the molten salt exacerbates the degradation of both the monolithic YSZ coating and the composite YSZ/Al{sub 2}O{sub 3} system. The formation of low-melting Na{sub 2}O-V{sub 2}O{sub 5}-Al{sub 2}O{sub 3} liquid phase is responsible for degradation of the Al{sub 2}O{sub 3} overlay. The Al{sub 2}O{sub 3} overlay acts as a barrier against the infiltration of the molten salt into the YSZ coating during exposure to the molten salt mixture with <5wt% vanadate. In the next reporting period, we will use XPS and SIMS to study the interactions between alumina overlay and molten salt containing vanadate.

  16. A nanometric Rh overlayer on a metal foil surface as a highly efficient three-way catalyst

    NASA Astrophysics Data System (ADS)

    Misumi, Satoshi; Yoshida, Hiroshi; Hinokuma, Satoshi; Sato, Tetsuya; Machida, Masato

    2016-07-01

    Pulsed arc-plasma (AP) deposition of an Rh overlayer on an Fe–Cr–Al stainless steel foil produced a composite material that exhibited high activity for automotive three-way catalysis (TWC). The AP pulses deposited metallic Rh nanoparticles 1–3 nm in size, whose density on the surface increased with the number of pulses. This led to coalescence and grain growth on the foil surface and the eventual formation of a uniform two-dimensional Rh overlayer. Full coverage of the 51 μm-thick flat foil by a 3.2 nm-thick Rh overlayer was achieved after 1,000 pulses. A simulated TWC reaction using a miniature honeycomb fabricated using flat and corrugated foils with the Rh overlayers exhibited successful light-off at a practical gaseous hourly space velocity of 1.2 × 105 h‑1. The turnover frequency for the NO–CO reaction over the metallic honeycomb catalyst was ca. 80-fold greater than that achieved with a reference Rh/ZrO2-coated cordierite honeycomb prepared using a conventional wet impregnation and slurry coating procedure. Despite the nonporosity and low surface area of the foil-supported Rh overlayer compared with conventional powder catalysts (Rh/ZrO2), it is a promising alternative design for more efficient automotive catalysts that use less Rh loading.

  17. Assessment of Potential Location of High Arsenic Contamination Using Fuzzy Overlay and Spatial Anisotropy Approach in Iron Mine Surrounding Area

    PubMed Central

    Wirojanagud, Wanpen; Srisatit, Thares

    2014-01-01

    Fuzzy overlay approach on three raster maps including land slope, soil type, and distance to stream can be used to identify the most potential locations of high arsenic contamination in soils. Verification of high arsenic contamination was made by collection samples and analysis of arsenic content and interpolation surface by spatial anisotropic method. A total of 51 soil samples were collected at the potential contaminated location clarified by fuzzy overlay approach. At each location, soil samples were taken at the depth of 0.00-1.00 m from the surface ground level. Interpolation surface of the analysed arsenic content using spatial anisotropic would verify the potential arsenic contamination location obtained from fuzzy overlay outputs. Both outputs of the spatial surface anisotropic and the fuzzy overlay mapping were significantly spatially conformed. Three contaminated areas with arsenic concentrations of 7.19 ± 2.86, 6.60 ± 3.04, and 4.90 ± 2.67 mg/kg exceeded the arsenic content of 3.9 mg/kg, the maximum concentration level (MCL) for agricultural soils as designated by Office of National Environment Board of Thailand. It is concluded that fuzzy overlay mapping could be employed for identification of potential contamination area with the verification by surface anisotropic approach including intensive sampling and analysis of the substances of interest. PMID:25110751

  18. High temperature polymer concrete compositions

    DOEpatents

    Fontana, Jack J.; Reams, Walter

    1985-01-01

    This invention is concerned with a polymer concrete composition, which is a two-component composition useful with many bases including metal. Component A, the aggregate composition, is broadly composed of silica, silica flour, portland cement, and acrylamide, whereas Component B, which is primarily vinyl and acrylyl reactive monomers, is a liquid system. A preferred formulation emphasizing the major necessary components is as follows: ______________________________________ Component A: Silica sand 60-77 wt. % Silica flour 5-10 wt. % Portland cement 15-25 wt. % Acrylamide 1-5 wt. % Component B: Styrene 50-60 wt. % Trimethylolpropane 35-40 wt. % trimethacrylate ______________________________________ and necessary initiators, accelerators, and surfactants.

  19. Annotated Bibliography: Polymers in Concrete.

    DTIC Science & Technology

    1982-10-01

    example, the untreated cements let water through the 2 -ton pressure after 7 days aging, while cement containing 33 wt. percent resin No. 89 ( prepared ...100 parts were mixed with 300 parts local zone 2 concreting (14 0 mesh and 45 parts 40 percent II latex ( prepared by aq. emulsion poly - merization...condition for polymer-modified mortars using special super high early strength cement is the combined air and water cure such as 2 -day-20*C-moist, 5-day-20°C

  20. Spall Damage of Concrete Structures

    DTIC Science & Technology

    1988-06-01

    likely also strain-rate sensitive . Fiber-reinforced concrete has been extensively studied. Various types of fiber material, including nylon, glass, and...60/40) 0.95 AMATOL (50/50) 0.97 ANFO (9416 Am Nil Fuel oil) 0.82 1-100 Composition A-3 1.09 1.07 5-50 Composition B 1.11 0.98 5-50 Composition C-4 1.37...defines the boundary between threshold spall and medium spall and deflections less than 4.17 percent of the free span. The heavy damage curve defines

  1. Application of concrete in marine structures

    SciTech Connect

    Rashid, A.; Nygaard, C.

    1997-07-01

    The use of concrete in marine environment has gained tremendous popularity in the past decade and is continued to be a very popular material for marine industry in the world today. It has a very diversified use from large offshore platforms and floating structures in the North Sea, Canada and South America to offshore loading terminals and junction platforms in shallow waters in the marshes of southern Louisiana in the Gulf of Mexico. Also, precast concrete sections are extensively used all over the world in the construction of marine structures. Because of their large variety of shapes and sizes, they can be tailored to fit multiple applications in marine environment. The added quality control in the fabrication yard and the ease of installation by lifting makes them a very attractive option. The use of precast concrete sections is gaining a lot of popularity in South America. A lot of fabrication yards are manufacturing these sections locally. There are hundreds of offshore concrete platforms utilizing these sections in Lake Maracaibo, Venezuela. The paper discusses the use of concrete for offshore structures including floaters. It describes some general concepts and advantages to be gained by the use of concrete (precast and cast-in-place) in marine environment. It also discusses some general design considerations required for the use of different types of precast concrete sections that can be utilized for oil and gas platforms and loading terminals. Lastly the paper describes some typical examples of concrete platforms built out of concrete piles, precast concrete girders and beam sections and concrete decking.

  2. 36. VAL, DETAIL OF TYPICAL INTERIOR OF CONCRETE 'A' FRAME ...

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

    36. VAL, DETAIL OF TYPICAL INTERIOR OF CONCRETE 'A' FRAME STRUCTURE SHOWING PAINTED CONCRETE WALLS, CONCRETE STAIRS AND INTERIOR WOOD DOOR. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

  3. Overlay coating degradation by simultaneous oxidation and coating/substrate interdiffusion. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Nesbitt, J. A.

    1983-01-01

    Degradation of NiCrAlZr overlay coatings on various NiCrAl substrates was examined after cyclic oxidation. Concentration/distance profiles were measured in the coating and substrate after various oxidation exposures at 1150 C. For each stubstrate, the Al content in the coating decreased rapidly. The concentration/distance profiles, and particularly that for Al, reflected the oxide spalling resistance of each coated substrate. A numerical model was developed to simulate diffusion associated with overlay-coating degradation by oxidation and coating/substrate interdiffusion. Input to the numerical model consisted of the Cr and Al content of the coating and substrate, ternary diffusivities, and various oxide spalling parameters. The model predicts the Cr and Al concentrations in the coating and substrate after any number of oxidation/thermal cycles. The numerical model also predicts coating failure based on the ability of the coating to supply sufficient Al to the oxide scale. The validity of the model was confirmed by comparison of the predicted and measured concentration/distance profiles. The model was subsequently used to identify the most critical system parameters affecting coating life.

  4. Optical fibre long period grating spectral actuators utilizing ferrofluids as outclading overlayers

    NASA Astrophysics Data System (ADS)

    Konstantaki, M.; Candiani, A.; Pissadakis, S.

    2011-03-01

    Results are presented on the spectral tuning of optical fibre long period gratings utilizing water and oil based ferrofluids as outclading overlayers, under static magnetic field stimulus. Two approaches are adopted for modifying the ambient refractive index at the position of the long period grating. In the first approach, a water based ferrofluid is controllably translated along the length of the grating via a magnetic field. Changes as high as 7.5nm and 6.5dB are monitored in the wavelength and strength, respectively, of the attenuation bands of the grating. The repeatable performance of this device for repetitive forward and backward translation verifies that no ferrofluidic residue is left on the fibre, due to silanization cladding functionalisation. In the second approach, the refractive index of an oil based ferrofluidic overlayer is modified through the magneto-optical effect. For an applied static magnetic field in the order of 400 Gauss the strength of the attenuation band of the grating is modified by more than 10% while its spectral position remains unaffected. Accordingly for the implementation of the last approach, the magnetically induced refractive index changes of ferrofluids of different solution concentrations are studied by employing diffraction efficiency measurements.

  5. Single-Layer Limit of Metallic Indium Overlayers on Si(111).

    PubMed

    Park, Jae Whan; Kang, Myung Ho

    2016-09-09

    Density-functional calculations are used to identify one-atom-thick metallic In phases grown on the Si(111) surface, which have long been sought in quest of the ultimate two-dimensional (2D) limit of metallic properties. We predict two metastable single-layer In phases, one sqrt[7]×sqrt[3] phase with a coverage of 1.4 monolayer (ML; here 1 ML refers to one In atom per top Si atom) and the other sqrt[7]×sqrt[7] phase with 1.43 ML, which indeed agree with experimental evidences. Both phases reveal quasi-1D arrangements of protruded In atoms, leading to 2D-metallic but anisotropic band structures and Fermi surfaces. This directional feature contrasts with the free-electron-like In-overlayer properties that are known to persist up to the double-layer thickness, implying that the ultimate 2D limit of In overlayers may have been achieved in previous studies of double-layer In phases.

  6. Study of spread spectrum multiple access systems for satellite communications with overlay on current services

    NASA Technical Reports Server (NTRS)

    Ha, Tri T.; Pratt, Timothy

    1989-01-01

    The feasibility of using spread spectrum techniques to provide a low-cost multiple access system for a very large number of low data terminals was investigated. Two applications of spread spectrum technology to very small aperture terminal (VSAT) satellite communication networks are presented. Two spread spectrum multiple access systems which use a form of noncoherent M-ary FSK (MFSK) as the primary modulation are described and the throughput analyzed. The analysis considers such factors as satellite power constraints and adjacent satellite interference. Also considered is the effect of on-board processing on the multiple access efficiency and the feasibility of overlaying low data rate spread spectrum signals on existing satellite traffic as a form of frequency reuse is investigated. The use of chirp is examined for spread spectrum communications. In a chirp communication system, each data bit is converted into one or more up or down sweeps of frequency, which spread the RF energy across a broad range of frequencies. Several different forms of chirp communication systems are considered, and a multiple-chirp coded system is proposed for overlay service. The mutual interference problem is examined in detail and a performance analysis undertaken for the case of a chirp data channel overlaid on a video channel.

  7. Analysis of 2D periodic nanostructures with an oxide overlayer via spectroscopic ellipsometry.

    PubMed

    Ghong, T H; Byun, J S; Han, S-H; Chung, J-M; Kim, Y D

    2011-07-01

    The accurate nondestructive determination of the shapes or critical dimensions of periodic nanostructures is essential to the current integrated-circuits technology. Optical critical dimension (OCD) metrology is fast, nondestructive, and can be used in air, allows higher sampling rates compared to the non-optical methods such as scanning electron microscopy (SEM) or atomic-force microscopy (AFM), and does not damage the sample. The data are typically analyzed via rigorous coupled-wave analysis (RCWA), where the sample is modeled as a series of layers whose dimensional parameters are determined by a least-squares fit. The layers are typically approximated as a combination of core material and ambient. Oxide overlayers and surface roughness are common, however, and call into question two-phase approximation. In this study, a structure that is periodic in two dimensions and that is coated with a thin (3 nm) oxide was studied, and an extension of the RCWA method that allows structural information to be extracted from optical data even in the presence of oxide overlayers or surface roughness was developed.

  8. An efficient mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks

    NASA Astrophysics Data System (ADS)

    Yu, Xiaojun; Xiao, Gaoxi; Cheng, Tee Hiang

    2014-08-01

    This paper proposes an efficient overlay multicast provisioning (OMP) mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks. To facilitate request provisioning, OMP jointly utilizes a data learning (DL) scheme on the IP/MPLS layer for logical link cost estimation, and a lightpath fragmentation (LPF) based method on the WDM layer for improving resource sharing in grooming process. Extensive simulations are carried out to evaluate the performance of OMP mechanism under different traffic loads, with either limited or unlimited port resources. Simulation results demonstrate that OMP significantly outperforms the existing methods. To evaluate the respective influences of the DL scheme and the LPF method on OMP performance, provisioning mechanisms only utilizing either the IP/MPLS layer DL scheme or the WDM layer LPF method are also devised. Comparison results show that both DL and LPF methods help improve OMP blocking performance, and contribution from the DL scheme is more significant when the fixed routing and first-fit wavelength assignment (RWA) strategy is adopted on the WDM layer. Effects of a few other factors, including definition of connection cost to be reported by the WDM layer to the IP/MPLS layer and WDM-layer routing method, on OMP performance are also evaluated.

  9. Platinum and Palladium Overlayers Dramatically Enhance the Activity of Ruthenium Nanotubes for Alkaline Hydrogen Oxidation

    SciTech Connect

    St. John, Samuel; Atkinson, Robert W.; Unocic, Kinga A.; Unocic, Raymond R.; Zawodzinski, Thomas A.; Papandrew, Alexander B.

    2015-10-18

    Templated vapor synthesis and thermal annealing were used to synthesize unsupported metallic Ru nanotubes with Pt or Pd overlayers. By controlling the elemental composition and thickness of these overlayers, we obtain nanostructures with very high alkaline hydrogen oxidation activity. For nanotubes with a nominal atomic composition of Ru0.90Pt0.10 display a surface-specific activity (2.4 mA/cm2) that is 35 times greater than that of pure Ru nanotubes at a 50 mV overpotential and 2.5 times greater than that of pure Pt nanotubes (0.98 mA/cm2). The surface-segregated structure also confers dramatically increased Pt utilization efficiency. We find a platinum-mass-specific activity of 1240 A/gPt for the optimized nanotube versus 280 A/gPt for carbon-supported Pt nanoparticles and 109 A/gPt for monometallic Pt nanotubes. Here, we attribute the enhancement of both area- and platinum-mass-specific activity to the atomic-scale homeomorphism of the nanotube form factor with adlayer-modified polycrystals. Subsurface ligand and bifunctional effects previously observed on segregated, adlayer-modified polycrystals are translated to nanoscale catalysts.

  10. Platinum and Palladium Overlayers Dramatically Enhance the Activity of Ruthenium Nanotubes for Alkaline Hydrogen Oxidation

    DOE PAGES

    St. John, Samuel; Atkinson, Robert W.; Unocic, Kinga A.; ...

    2015-10-18

    Templated vapor synthesis and thermal annealing were used to synthesize unsupported metallic Ru nanotubes with Pt or Pd overlayers. By controlling the elemental composition and thickness of these overlayers, we obtain nanostructures with very high alkaline hydrogen oxidation activity. For nanotubes with a nominal atomic composition of Ru0.90Pt0.10 display a surface-specific activity (2.4 mA/cm2) that is 35 times greater than that of pure Ru nanotubes at a 50 mV overpotential and 2.5 times greater than that of pure Pt nanotubes (0.98 mA/cm2). The surface-segregated structure also confers dramatically increased Pt utilization efficiency. We find a platinum-mass-specific activity of 1240 A/gPtmore » for the optimized nanotube versus 280 A/gPt for carbon-supported Pt nanoparticles and 109 A/gPt for monometallic Pt nanotubes. Here, we attribute the enhancement of both area- and platinum-mass-specific activity to the atomic-scale homeomorphism of the nanotube form factor with adlayer-modified polycrystals. Subsurface ligand and bifunctional effects previously observed on segregated, adlayer-modified polycrystals are translated to nanoscale catalysts.« less

  11. Hot Corrosion of Inconel 625 Overlay Weld Cladding in Smelting Off-Gas Environment

    NASA Astrophysics Data System (ADS)

    Mohammadi Zahrani, E.; Alfantazi, A. M.

    2013-10-01

    Degradation mechanisms and hot corrosion behavior of weld overlay alloy 625 were studied. Phase structure, morphology, thermal behavior, and chemical composition of deposited salt mixture on the weld overlay were characterized utilizing XRD, SEM/EDX, DTA, and ICP/OES, respectively. Dilution level of Fe in the weldment, dendritic structure, and degradation mechanisms of the weld were investigated. A molten phase formed on the weld layer at the operating temperature range of the boiler, which led to the hot corrosion attack in the water wall and the ultimate failure. Open circuit potential and weight-loss measurements and potentiodynamic polarization were carried out to study the hot corrosion behavior of the weld in the simulated molten salt medium at 873 K, 973 K, and 1073 K (600 °C, 700 °C, and 800 °C). Internal oxidation and sulfidation plus pitting corrosion were identified as the main hot corrosion mechanisms in the weld and boiler tubes. The presence of a significant amount of Fe made the dendritic structure of the weld susceptible to preferential corrosion. Preferentially corroded (Mo, Nb)-depleted dendrite cores acted as potential sites for crack initiation from the surface layer. The penetration of the molten phase into the cracks accelerated the cracks' propagation mainly through the dendrite cores and further crack branching/widening.

  12. Improving management performance of P2PSIP for mobile sensing in wireless overlays.

    PubMed

    Sendín-Raña, Pablo; González-Castaño, Francisco Javier; Gómez-Cuba, Felipe; Asorey-Cacheda, Rafael; Pousada-Carballo, José María

    2013-11-08

    Future wireless communications are heading towards an all-Internet Protocol (all-IP) design, and will rely on the Session Initiation Protocol (SIP) to manage services, such as voice over IP (VoIP). The centralized architecture of traditional SIP has numerous disadvantages for mobile ad hoc services that may be possibly overcome by advanced peer-to-peer (P2P) technologies initially developed for the Internet. In the context of mobile sensing, P2PSIP protocols facilitate decentralized and fast communications with sensor-enabled terminals. Nevertheless, in order to make P2PSIP protocols feasible in mobile sensing networks, it is necessary to minimize overhead transmissions for signaling purposes, which reduces the battery lifetime. In this paper, we present a solution to improve the management of wireless overlay networks by defining an adaptive algorithm for the calculation of refresh time. The main advantage of the proposed algorithm is that it takes into account new parameters, such as the delay between nodes, and provides satisfactory performance and reliability levels at a much lower management overhead than previous approaches. The proposed solution can be applied to many structured P2P overlays or P2PSIP protocols. We evaluate it with Kademlia-based distributed hash tables (DHT) and dSIP.

  13. The Effects of a Dynamic Spectrum Access Overlay in LTE-Advanced Networks

    SciTech Connect

    Juan D. Deaton; Ryan E. lrwin; Luiz A. DaSilva

    2011-05-01

    As early as 2014, wireless network operators spectral capacity will be overwhelmed by a data tsunami brought on by new devices and applications. To augment spectral capacity, operators could deploy a Dynamic Spectrum Access (DSA) overlay. In the light of the many planned Long Term Evolution (LTE) network deployments, the affects of a DSA overlay have not been fully considered into the existing LTE standards. Coalescing many different aspects of DSA, this paper develops the Spectrum Accountability (SA) framework. The SA framework defines specific network element functionality, protocol interfaces, and signaling flow diagrams for LTE to support service requests and enforce rights of responsibilities of primary and secondary users, respectively. We also include a network simulation to quantify the benefits of using DSA channels to augment capacity. Based on our simulation we show that, network operators can benefit up to %40 increase in operating capacity when sharing DSA bands to augment spectral capacity. With our framework, this paper could serve as an guide in developing future LTE network standards that include DSA.

  14. Composite optical fiber polarizer with ternary copolymer overlay for large range modulation of phase difference

    NASA Astrophysics Data System (ADS)

    Cui, Minxin; Tian, Xiujie; Zou, Gang; Zhu, Bing; Zhang, Qijin

    2017-04-01

    In this work, a ternary copolymer composed of (E)-2-(4-((4-isocyanophenyl) diazenyl) phenoxy) ethyl methacrylate (2-CN), methacrylisobutyl polyhedral oligomeric silsesquioxane (MAPOSS) and 2,2,2-trifluoroethyl methacrylate (TFEMA) is synthesized and used as the overlay for composite optical fiber, in which cage-like POSS component and fluorine-containing component are used to reduce refractive index, and azobenzene component is used to finely manipulate the refractive indices in two orthogonal directions through photo-induced orientation under irradiation of polarized light. Before irradiation, the refractive index of terpolymer (1.4503) is slightly higher than that of the core material (1.4489) of commercial silica single-mode fiber, which is obtained by optimizing the amount of each monomer. After the irradiation of 435 nm polarized light, refractive indices of the overlay in two orthogonal directions decrease, and two values have been finely manipulated so that one is higher and another is lower than the refractive index of the fiber core by optimizing irradiation time. In this way, a radial loss type fiber polarization modulator is obtained. By changing the polarization direction of the irradiation at 435 nm, the polarization of propagating light at 1550 nm in the fiber can also be modulated continuously. The maximum change of phase difference is about 300°, making the device useful as a quarter-wave plate or a half-wave plate.

  15. Improving Management Performance of P2PSIP for Mobile Sensing in Wireless Overlays

    PubMed Central

    Sendín-Raña, Pablo; González-Castaño, Francisco Javier; Gómez-Cuba, Felipe; Asorey-Cacheda, Rafael; Pousada-Carballo, José María

    2013-01-01

    Future wireless communications are heading towards an all-Internet Protocol (all-IP) design, and will rely on the Session Initiation Protocol (SIP) to manage services, such as voice over IP (VoIP). The centralized architecture of traditional SIP has numerous disadvantages for mobile ad hoc services that may be possibly overcome by advanced peer-to-peer (P2P) technologies initially developed for the Internet. In the context of mobile sensing, P2PSIP protocols facilitate decentralized and fast communications with sensor-enabled terminals. Nevertheless, in order to make P2PSIP protocols feasible in mobile sensing networks, it is necessary to minimize overhead transmissions for signaling purposes, which reduces the battery lifetime. In this paper, we present a solution to improve the management of wireless overlay networks by defining an adaptive algorithm for the calculation of refresh time. The main advantage of the proposed algorithm is that it takes into account new parameters, such as the delay between nodes, and provides satisfactory performance and reliability levels at a much lower management overhead than previous approaches. The proposed solution can be applied to many structured P2P overlays or P2PSIP protocols. We evaluate it with Kademlia-based distributed hash tables (DHT) and dSIP PMID:24217358

  16. The Sapphire (0001) Surface, Clean and with d-metal Overlayers: Density Functional - LDA Results

    NASA Astrophysics Data System (ADS)

    Verdozzi, C.; Jennison, D. R.; Schultz, P. A.; Sears, M. P.

    1998-03-01

    Previous theoretical work for the a-Al2O3(0001) surface mostly used very thin slabs, and limited theoretical information is available on the binding of metal overlayers. Also, no systematic information is available about the dependence of the metal-ceramic interaction on metal coverage. We present here results using the local density approximation for the structural and electronic properties of the a-Al2O3(0001) surface, with and without d-metal overlayers Pt, Ag, Cu, and with sufficiently thick slabs to find the bottom of the unusually large and deep surface relaxation in this material. Our thick slab site-optimized calculations are performed for 1, 2/3 and 1/3 monolayer (ML) coverage. The adhesion energy and the nature of the interfacial bond vary greatly with metal coverage and can be understood in terms of the relative roles of the surface Madelung potential and the strength of the lateral metal-metal bond. Our study should in principle succeed in bracketing the phenomenology of adhesion and wetting at least for the right-most part of the d-metal periodic table. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000. Corresponding author: claudio@sandia.gov.

  17. Weldability of Fe-Al-Cr Overlay Coatings for CorrosionProtection in Oxidizing/Sulfidizing Environments

    SciTech Connect

    Regina, JR

    2003-03-04

    The effect of chromium additions to the weldability of Fe-Al based overlay claddings are currently being investigated for the corrosion protection of boiler tubes in Low NOx furnaces. The primary objective of this research is to identify weldable (crack-free) Fe-Al-Cr weld overlay coating compositions that provide corrosion resistance over long exposure times. During the current project phase, preliminary corrosion testing was conducted on several ternary Fe-Al-Cr alloys in two types of gaseous corrosion environments. These long-term corrosion tests were used to develop a target weld composition matrix and serve as a base line for future corrosion tests. Preliminary Fe-Al based welds with various aluminum concentrations and one ternary Fe-Al-Cr weld overlay were successfully deposited using a Gas Tungsten Arc Welding (GTAW) process and cracking susceptibility was evaluated on these coatings.

  18. A van der Waals density functional study of adenine on graphene: Single molecular adsorption and overlayer binding

    SciTech Connect

    Berland, Kristian; Cooper, Valentino R; Langreth, David C.; Schroder, Prof. Elsebeth; Chakarova-Kack, Svetla

    2011-01-01

    The adsorption of an adenine molecule on graphene is studied using a first-principles van der Waals functional (vdW-DF) [Dion et al., Phys. Rev. Lett. 92, 246401 (2004)]. The cohesive energy of an ordered adenine overlayer is also estimated. For the adsorption of a single molecule, we determine the optimal binding configuration and adsorption energy by translating and rotating the molecule. The adsorption energy for a single molecule of adenine is found to be 711 meV, which is close to the calculated adsorption energy of the similar-sized naphthalene. Based on the single molecular binding configuration, we estimate the cohesive energy of a two-dimensional ordered overlayer. We find a significantly stronger binding energy for the ordered overlayer than for single-molecule adsorption.

  19. Quick-setting concrete and a method for making quick-setting concrete

    DOEpatents

    Wagh, A.S.; Singh, D.; Pullockaran, J.D.; Knox, L.

    1997-04-29

    A method for producing quick setting concrete is provided comprising mixing a concrete dry mixture with carbonate solution to create a slurry, and allowing the slurry to cure. The invention also provides for a quick setting concrete having a predetermined proportion of CaCO{sub 3} of between 5 and 23 weight percent of the entire concrete mixture, and whereby the concrete has a compression strength of approximately 4,000 pounds per square inch (psi) within 24 hours after pouring. 2 figs.

  20. Testing of plain and fibrous concrete single cavity prestressed concrete reactor vessel models

    SciTech Connect

    Oland, C.B.

    1985-01-01

    Two single-cavity prestressed concrete reactor vessel (PCRV) models were fabricated and tested to failure to demonstrate the structural response and ultimate pressure capacity of models cast from high-strength concretes. Concretes with design compressive strengths in excess of 70 MPa (10,000 psi) were developed for this investigation. One model was cast from plain concrete and failed in shear at the head region. The second model was cast from fiber reinforced concrete and failed by rupturing the circumferential prestressing at the sidewall of the structure. The tests also demonstrated the capabilities of the liner system to maintain a leak-tight pressure boundary. 3 refs., 4 figs.

  1. Radionuclide Retention in Concrete Wasteforms

    SciTech Connect

    Wellman, Dawn M.; Jansik, Danielle P.; Golovich, Elizabeth C.; Cordova, Elsa A.

    2012-09-24

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. Data collected throughout the course of this work will be used to quantify the efficacy of concrete wasteforms, similar to those used in the disposal of LLW and MLLW, for the immobilization of key radionuclides (i.e., uranium, technetium, and iodine). Data collected will also be used to quantify the physical and chemical properties of the concrete affecting radionuclide retention.

  2. Investigation of modified asphalt concrete

    NASA Astrophysics Data System (ADS)

    Zimich, Vita

    2016-01-01

    Currently the problem of improving the asphalt quality is very urgent. It is used primarily as topcoats exposed to the greatest relative to the other layers of the road, dynamic load - impact and shear. The number of cars on the road, the speed of their movement, as well as the traffic intensity increase day by day. We have to upgrade motor roads, which entails a huge cost. World experience shows that the issue is urgent not only in Russia, but also in many countries in Europe, USA and Asia. Thus, the subject of research is the resistance of asphalt concrete to water and its influence on the strength of the material at different temperatures, and resistance of pavement to deformation. It is appropriate to search for new modifiers for asphaltic binder and mineral additives for asphalt mix to form in complex the skeleton of the future asphalt concrete, resistant to atmospheric condensation, soil characteristics of the road construction area, as well as the growing road transport load. The important task of the work is searching special modifying additives for bitumen binder and asphalt mixture as a whole, which will improve the quality of highways, increasing the period between repairs. The methods described in the normative-technical documentation were used for the research. The conducted research allowed reducing the frequency of road maintenance for 7 years, increasing it from 17 to 25 years.

  3. A comparative study between xerographic, computer-assisted overlay generation and animated-superimposition methods in bite mark analyses.

    PubMed

    Tai, Meng Wei; Chong, Zhen Feng; Asif, Muhammad Khan; Rahmat, Rabiah A; Nambiar, Phrabhakaran

    2016-09-01

    This study was to compare the suitability and precision of xerographic and computer-assisted methods for bite mark investigations. Eleven subjects were asked to bite on their forearm and the bite marks were photographically recorded. Alginate impressions of the subjects' dentition were taken and their casts were made using dental stone. The overlays generated by xerographic method were obtained by photocopying the subjects' casts and the incisal edge outlines were then transferred on a transparent sheet. The bite mark images were imported into Adobe Photoshop® software and printed to life-size. The bite mark analyses using xerographically generated overlays were done by comparing an overlay to the corresponding printed bite mark images manually. In computer-assisted method, the subjects' casts were scanned into Adobe Photoshop®. The bite mark analyses using computer-assisted overlay generation were done by matching an overlay and the corresponding bite mark images digitally using Adobe Photoshop®. Another comparison method was superimposing the cast images with corresponding bite mark images employing the Adobe Photoshop® CS6 and GIF-Animator©. A score with a range of 0-3 was given during analysis to each precision-determining criterion and the score was increased with better matching. The Kruskal Wallis H test showed significant difference between the three sets of data (H=18.761, p<0.05). In conclusion, bite mark analysis using the computer-assisted animated-superimposition method was the most accurate, followed by the computer-assisted overlay generation and lastly the xerographic method. The superior precision contributed by digital method is discernible despite the human skin being a poor recording medium of bite marks.

  4. Construction Cluster Volume IV: [Concrete Work].

    ERIC Educational Resources Information Center

    Pennsylvania State Dept. of Justice, Harrisburg. Bureau of Correction.

    The document is the fourth of a series, to be integrated with a G.E.D. program, containing instructional materials for the construction cluster. The volume focuses on concrete work and consists of 20 instructional units which require a month of study. The units include: (1) uses of concrete and occupational information; (2) soils, drainage, and…

  5. RADON GENERATION AND TRANSPORT THROUGH CONCRETE FOUNDATIONS

    EPA Science Inventory

    The report gives results of an examination of radon generation and transport through Florida residential concretes for their contribution to indoor radon concentrations. Radium concentrations in the 11 concretes tested were all <2.5 pCi/g and radon emanation coefficients were all...

  6. Assessing the Concreteness of Relational Representation

    ERIC Educational Resources Information Center

    Rein, Jonathan R.; Markman, Arthur B.

    2010-01-01

    Research has shown that people's ability to transfer abstract relational knowledge across situations can be heavily influenced by the concrete objects that fill relational roles. This article provides evidence that the concreteness of the relations themselves also affects performance. In 3 experiments, participants viewed simple relational…

  7. "Concreteness Fading" Promotes Transfer of Mathematical Knowledge

    ERIC Educational Resources Information Center

    McNeil, Nicole M.; Fyfe, Emily R.

    2012-01-01

    Recent studies have suggested that educators should avoid concrete instantiations when the goal is to promote transfer. However, concrete instantiations may benefit transfer in the long run, particularly if they are "faded" into more abstract instantiations. Undergraduates were randomly assigned to learn a mathematical concept in one of three…

  8. An Endochronic Plasticity Theory for Concrete.

    DTIC Science & Technology

    1985-02-20

    Strain Curves for Concrete Under Multiaxial Load His- tories," CEAE Department, Univ. of Colo., Boulder. 18. Stankowski, T., and K. H. Gerstle (1983...T. (1983), "Concrete Under Multiaxial Load Histories," M. S. Thesis, CEAE Department, University of Colorado, Boulder. 31. Valanis, K. C., and C. F

  9. Properties and uses of concrete, appendix B

    NASA Technical Reports Server (NTRS)

    Corley, Gene

    1992-01-01

    Concretes that can now be formed have properties which may make them valuable for lunar or space construction. These properties include high compressive strength, good flexural strength (when reinforced), and favorable responses to temperature extremes (even increased strength at low temperatures). These and other properties of concrete are discussed.

  10. A Study on the Cover Failure in Concrete Structure Following Concrete Deterioration

    SciTech Connect

    Choo, Y.H.; Lee, Y.H.; Lee, C.M.; Lee, K.J.

    2008-07-01

    The RC (Reinforced Concrete) structures in the spent fuel dry storage is required structural integrity for a long period of the service life time. A study on the concrete cracking behavior by stress on concrete is necessary for life time estimation of structures because concrete cracking can reduce the radiation shielding performance and deteriorate the durability of spent fuel dry storage. The purpose of this study is to analyze the relationship between the range of the steel expansion and the crack creation and propagation using the ABAQUS tool. Parameters used in this study were concrete strength, concrete cover depth and the steel diameter. The value of steel radius to volume expansion was applied to suppose the expansion of reinforcing bar under the load condition. As a result of this case study, it is confirmed that the critical steel expansion which can initiate cracking is proportional to tensile strength. And primary factors which effect crack creation of concrete cover are in order of concrete strength, cover thickness and steel diameter. If concrete strength is lowered about its 30%, the rate of surface crack occurrence accelerates 15 times maximally. The critical expansion value of steel increased as the increment of concrete cover depth. The surface cracking of concrete cover was created at the value of steel expansion, ranging from 0.019 to 0.051 mm under the cover depth 50 mm. (authors)

  11. Supporting Concrete Visual Thinking in Multiplicative Reasoning: Difficulties and Opportunities.

    ERIC Educational Resources Information Center

    Kaput, James J.

    1989-01-01

    Describes environments for concretely enacting multiplication and division. Discusses difficulties occurring when students use one of the concrete environments to model situations involving modified environments. (YP)

  12. Multifunctional bowtie-shaped ridge aperture for overlay alignment in plasmonic direct writing lithography using a contact probe.

    PubMed

    Oh, Seonghyeon; Lee, Taekyong; Hahn, Jae W

    2013-07-01

    We propose a scheme of overlay alignment for plasmonic lithography using a scanning contact probe. Using two resonances of a ridge aperture in a metal film, we introduce the aperture's multifunctional characteristics for patterning and alignment at different wavelengths. To verify this idea, we measure an image of an alignment mark using a scanning ridge aperture and determine the reference point for the alignment. We then analyze the uncertainty of the alignment method with respect to the image data noise and compare the numerical results with the experimental results. The uncertainty of the overlay alignment method is shown to be less than approximately 2 nm.

  13. IMPERMEABLE THIN AL2O3 OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

    SciTech Connect

    Scott X. Mao

    2002-01-31

    In order to improve the hot corrosion resistance of conventional YSZ TBC system, the overlay of Al{sub 2}O{sub 3} coating was deposited on the TBC by EB-PVD techniques. Hot corrosion tests were carried out on the TBC with and without Al{sub 2}O{sub 3} coating in molten salts mixtures (Na{sub 2}SO{sub 4} + 5%V{sub 2}O{sub 5}) at 950 C for 10h. The microstructures of TBC and overlay before and after exposure were examined by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDX) and X-ray diffraction (XRD). It has been found that TBC will react with V{sub 2}O{sub 5} to form YVO{sub 4}. A substantial amount of M-phase was formed due to the leaching of Y{sub 2}O{sub 3} from YSZ. Al{sub 2}O{sub 3} overlay coating deposited by EB-PVD was dense, continues and adherent to the TBC. As a result, overlay Al{sub 2}O{sub 3} coating can prevent the YSZ from the attack by molten salts containing vanadium and arrest the penetration of salts into the YSZ along porous and cracks in the YSZ TBC, although there were some cracks in overlay Al{sub 2}O{sub 3} coating and at the interface between alumina and zirconia formed during hot corrosion tests due to the presence of tensile stress in the alumina coating. In the next reporting period, we will study the mechanisms of cracking of the overlay Al{sub 2}O{sub 3} layer and finish the hot corrosion tests of TBC with Al{sub 2}O{sub 3} coating deposited by high velocity oxy-fuel (HVOF) technique. The hot corrosion test of TBC with EB-PVD deposited Al{sub 2}O{sub 3} coating will be again performed. However before hot corrosion tests, a post-annealing will be carried out in vacuum (residual pressure 10{sup -3} Pa) at 1273K for 1h in order to transform the as-sputtered Al{sub 2}O{sub 3} overlay to crystalline {alpha}-Al{sub 2}O{sub 3} overlay.

  14. IMPERMEABLE THIN AL2O3 OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

    SciTech Connect

    Scott X. Mao

    2002-08-31

    In order to improve the hot corrosion resistance of conventional YSZ TBC system, the overlay of Al{sub 2}O{sub 3} coating was deposited on the TBC by EB-PVD techniques. Hot corrosion tests were carried out on the TBC with and without Al{sub 2}O{sub 3} coating in molten salts mixtures (Na{sub 2}SO{sub 4} + 5%V{sub 2}O{sub 5}) at 950 C for different time up to 100h. The microstructures of TBC and overlay before and after exposure were examined by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDX) and X-ray diffraction (XRD). It has been found that TBC will react with V{sub 2}O{sub 5} to form YVO{sub 4}. The amount of M-phase, which was formed due to the leaching of Y{sub 2}O{sub 3} from YSZ, was increased with corrosion time. Al{sub 2}O{sub 3} overlay coating deposited by EB-PVD was dense, continues and adherent to the TBC. As a result, overlay Al{sub 2}O{sub 3} coating can prevent the YSZ from the attack by molten salts containing vanadium and decrease the penetration of salts into the YSZ along porous and cracks in the YSZ TBC. The amount of M-phase formed in YSZ covered with an overlay Al{sub 2}O{sub 3} is substantially lower than that formed in conventional YSZ TBC, even after 100h exposure to the molten salts. In the next reporting period, the hot corrosion test of TBC with EB-PVD deposited Al{sub 2}O{sub 3} coating will be again performed. However before hot corrosion tests, the post-annealing will be carried out in vacuum (residual pressure 10 -3 Pa) at 1273K for 1h in order to transform the as-sputtered Al{sub 2}O{sub 3} overlay to crystalline {alpha}-Al{sub 2}O{sub 3} overlay. In addition, the effect of the thickness of overlay Al{sub 2}O{sub 3} on corrosion resistance will also be investigated.

  15. IMPERMEABLE THIN AL2O3 OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

    SciTech Connect

    Scott X. Mao

    2004-08-31

    To improve the hot corrosion resistance of YSZ thermal barrier coatings, a 25 {micro}m and a 2 {micro}m thick Al{sub 2}O{sub 3} overlay were deposited by HVOF thermal spray onto to the surface of YSZ coating. Oxidation at high temperature and hot corrosion tests showed that Al{sub 2}O{sub 3} overlay deposited on the YSZ TBCs surface can not only reduce the hot corrosion rate, but also significantly prevents the bond coat from oxidation.

  16. The presence of a (1 × 1) oxygen overlayer on ZnO(0001) surfaces and at Schottky interfaces

    NASA Astrophysics Data System (ADS)

    Schlepütz, Christian M.; Yang, Yongsoo; Husseini, Naji S.; Heinhold, Robert; Kim, Hyung-Suk; Allen, Martin W.; Durbin, Steven M.; Clarke, Roy

    2012-03-01

    The atomic surface and interface structures of uncoated and metal-coated epi-polished ZnO(0001) Zn-polar wafers were investigated via surface x-ray diffraction. All uncoated samples showed the presence of a fully occupied (1 × 1) overlayer of oxygen atoms located at the on-top position above the terminating Zn atom, a structure predicted to be unstable by several density functional theory calculations. The same oxygen overlayer was clearly seen at the interface of ZnO with both elemental and oxidized metal Schottky contact layers. No significant atomic relaxations were observed at surfaces and interfaces processed under typical device fabrication conditions.

  17. Aerated concrete with mineral dispersed reinforcing additives

    NASA Astrophysics Data System (ADS)

    Berdov, G. I.; Ilina, L. V.; Mukhina, I. N.; Rakov, M. A.

    2015-01-01

    To guarantee the production of aerated concrete with the lowest average density while ensuring the required strength it is necessary to use a silica component with a surface area of 250-300 m2 / kg. The article presents experimental data on grinding the silica component together with clinker to the optimum dispersion. This allows increasing the strength of non-autoclaved aerated concrete up to 33%. Furthermore, the addition to aerated concrete the mixture of dispersed reinforcing agents (wollastonite, diopside) and electrolytes with multiply charged cations and anions (1% Fe2 (SO4)3; Al2 (SO4)3) provides the growth of aerated concrete strength at 30 - 75%. As a cohesive the clinker, crushed together with silica and mineral supplements should be used. This increases the strength of aerated concrete at 65% in comparing with Portland cement.

  18. Recent biogenic phosphorite: Concretions in mollusk kidneys

    USGS Publications Warehouse

    Doyle, L.J.; Blake, N.J.; Woo, C.C.; Yevich, P.

    1978-01-01

    Phosphorite concretions have been detected in the kidneys of two widespread species ofmollusks, Mercenaria mercenaria and Argopecten irradians, which have relatively high population densities. These concretions are thefirst documentation of the direct biogenic formation of phosphorite grains. The concretions are principally amorphous calcium phosphate, which upon being heated yields an x-ray diffraction pattern which is essentially that of chlorapatite. These concretions appear to be a normal formation of the excretory process of mollusks under reproductive, environmental, or pollutant-induced stress. Biogenic production of phosphorite concretions over long periods of time and diagenetic change from amorphous to crystalline structure, coupled with secondary enrichment, may account for the formation of some marine phosphorite desposits which are not easily explained by the chemical precipitation- replacement hypothesis. Copyright ?? 1978 AAAS.

  19. Studies on recycled aggregates-based concrete.

    PubMed

    Rakshvir, Major; Barai, Sudhirkumar V

    2006-06-01

    Reduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design.

  20. Electrical Resistance Tomography imaging of concrete

    SciTech Connect

    Karhunen, Kimmo; Seppaenen, Aku; Lehikoinen, Anssi; Monteiro, Paulo J.M.; Kaipio, Jari P.

    2010-01-15

    We apply Electrical Resistance Tomography (ERT) for three dimensional imaging of concrete. In ERT, alternating currents are injected into the target using an array of electrodes attached to the target surface, and the resulting voltages are measured using the same electrodes. These boundary measurements are used for reconstructing the internal (3D) conductivity distribution of the target. In reinforced concrete, the metallic phases (reinforcing bars and fibers), cracks and air voids, moisture gradients, and the chloride distribution in the matrix carry contrast with respect to conductivity. While electrical measurements have been widely used to characterize the properties of concrete, only preliminary results of applying ERT to concrete imaging have been published so far. The aim of this paper is to carry out a feasibility evaluation with specifically cast samples. The results indicate that ERT may be a feasible modality for non-destructive evaluation of concrete.

  1. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS.

    SciTech Connect

    Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

    2001-03-22

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits.

  2. Radiation Damage In Reactor Cavity Concrete

    SciTech Connect

    Field, Kevin G; Le Pape, Yann; Naus, Dan J; Remec, Igor; Busby, Jeremy T; Rosseel, Thomas M; Wall, Dr. James Joseph

    2015-01-01

    License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has established a renewed focus on long-term aging of nuclear generating stations materials, and recently, on concrete. Large irreplaceable sections of most nuclear generating stations include concrete. The Expanded Materials Degradation Analysis (EMDA), jointly performed by the Department of Energy, the Nuclear Regulatory Commission and Industry, identified the urgent need to develop a consistent knowledge base on irradiation effects in concrete. Much of the historical mechanical performance data of irradiated concrete does not accurately reflect typical radiation conditions in NPPs or conditions out to 60 or 80 years of radiation exposure. To address these potential gaps in the knowledge base, The Electric Power Research Institute and Oak Ridge National Laboratory are working to disposition radiation damage as a degradation mechanism. This paper outlines the research program within this pathway including: (i) defining the upper bound of the neutron and gamma dose levels expected in the biological shield concrete for extended operation (80 years of operation and beyond), (ii) determining the effects of neutron and gamma irradiation as well as extended time at temperature on concrete, (iii) evaluating opportunities to irradiate prototypical concrete under accelerated neutron and gamma dose levels to establish a conservative bound and share data obtained from different flux, temperature, and fluence levels, (iv) evaluating opportunities to harvest and test irradiated concrete from international NPPs, (v) developing cooperative test programs to improve confidence in the results from the various concretes and research reactors, (vi) furthering the understanding of the effects of radiation on concrete (see companion paper) and (vii) establishing an international collaborative research and information exchange effort to leverage capabilities and knowledge.

  3. Creating Interactive Graphical Overlays in the Advanced Weather Interactive Processing System Using Shapefiles and DGM Files

    NASA Technical Reports Server (NTRS)

    Barrett, Joe H., III; Lafosse, Richard; Hood, Doris; Hoeth, Brian

    2007-01-01

    Graphical overlays can be created in real-time in the Advanced Weather Interactive Processing System (AWIPS) using shapefiles or Denver AWIPS Risk Reduction and Requirements Evaluation (DARE) Graphics Metafile (DGM) files. This presentation describes how to create graphical overlays on-the-fly for AWIPS, by using two examples of AWIPS applications that were created by the Applied Meteorology Unit (AMU) located at Cape Canaveral Air Force Station (CCAFS), Florida. The first example is the Anvil Threat Corridor Forecast Tool, which produces a shapefile that depicts a graphical threat corridor of the forecast movement of thunderstorm anvil clouds, based on the observed or forecast upper-level winds. This tool is used by the Spaceflight Meteorology Group (SMG) at Johnson Space Center, Texas and 45th Weather Squadron (45 WS) at CCAFS to analyze the threat of natural or space vehicle-triggered lightning over a location. The second example is a launch and landing trajectory tool that produces a DGM file that plots the ground track of space vehicles during launch or landing. The trajectory tool can be used by SMG and the 45 WS forecasters to analyze weather radar imagery along a launch or landing trajectory. The presentation will list the advantages and disadvantages of both file types for creating interactive graphical overlays in future AWIPS applications. Shapefiles are a popular format used extensively in Geographical Information Systems. They are usually used in AWIPS to depict static map backgrounds. A shapefile stores the geometry and attribute information of spatial features in a dataset (ESRI 1998). Shapefiles can contain point, line, and polygon features. Each shapefile contains a main file, index file, and a dBASE table. The main file contains a record for each spatial feature, which describes the feature with a list of its vertices. The index file contains the offset of each record from the beginning of the main file. The dBASE table contains records for each

  4. Lithographic overlay measurement precision and calibration and their effect on pattern registration optimization

    NASA Astrophysics Data System (ADS)

    Zavecz, Terrence E.

    1992-06-01

    Overlay of pattern registration is considered by some to be the most yield critical metrology element monitored in the semiconductor manufacturing process. Over the years, the aggressive demands of competitive chip design have constantly maintained these specifications at the process capability limit. This has driven the lithographer from somewhat simple process control techniques like optically read verniers, to computer automated overlay measurement systems whose outputs are applied to the estimation and correction of full field systematic error sources primarily as modeled wafer and lens pattern distortions. When modeled pattern distortions are used to optimize the lithographic overlay process, the point measurement of registration error is no longer the parameter of interest. Instead the lithographer wishes to measure and minimize the surface modeled pattern distortions such as translation, rotation, and magnification. Yet, often neglected is the fact that estimates of these parameters are influenced by measurement system errors resulting in a loss of precision in the estimate of the distortions and the false introduction of otherwise nonexistent distortions leading to improper determination of the true values for the lens. This paper describes the results of a screening simulation designed to determine the relative effects of measurement system errors on the distortion coefficient estimates produced by a pattern distortion model. The simulation confirms the somewhat obvious result that tool induced shift (TIS) translates directly into the estimate of the offset term of the model. In addition, the simulation indicates that errors in the measurement system pixel scale calibration directly scale all distortion estimates by the same factor. The variance of the measurement system sums with the variance of the stepper and inflates the standard error of the regression as well as the uncertainty of each lens parameter's estimate. Higher order nonlinearities or

  5. Density measurements of road overlays samples with nuclear gauges and a Step Frequency Radar

    NASA Astrophysics Data System (ADS)

    Fauchard, C.; Li, B.; Kadi, M.

    2012-04-01

    The density of Hot-Mix Asphalt layers (HMA) and thin overlays is an important parameter for the pavement quality and its long time performance. In the laboratory, the density could be measured with nuclear gauges based on the gamma rays absorption through cores samples drilled from the pavement. However, it is a destructive testing. For in-place control, the density could be measured with nuclear gauges based on the back-scattered gamma rays. But it is limited to overlays thickness greater than 3 cm. For both cases, nuclear gauges require specific training and certification for users. The use of a nuclear source (generally Cesium 137) is a major constraint for transportation and is a threat for operator safety. This work proposes a laboratory density measurement with an electromagnetic method, the Step Frequency Radar developped in our institute (Fauchard et al, 2009). It is based on the same physical principle than the Ground Penetrating Radar, but the used frequencies allow the study of very thin asphalt overlays less than 3 cm and the possible non-destructive measurement of in-place density with high performance. For this study, the dimensions of the device are designed to measure the density of slab samples (40*60*8 cm) in laboratory. The results are compared to the nuclear density measurement used in French Labs. Three kinds of slabs are implemented with four various degrees of compaction (88, 90, 92 and 94%) according to the French norm. Their composition is known and differs mainly with the nature of the aggregates (basalt, quartzite and limestone) that represent the main part of the mix materials. Then the permittivity of the samples is measured according to the reflected waves on surface and bottom slabs. A Complex Refractive Index Model gives the measured permittivity of the tested mix as a function of the compaction and the content, permittiviy and density of each component (filler, aggregates and bitumen). The obtained density is very closed to the

  6. Surface Morphology and Overlayer Formation Kinetics of OXYGEN/SILVER(110) Studied by Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Pai, Woei Wu.

    1995-01-01

    I have applied scanning tunneling microscopy (STM) to study clean and oxygen-covered vicinal Ag(110) surfaces at room temperature. Experimental results of surface morphology/stability, surface mass transport and surface chemical reactivity are presented. On clean vicinal Ag(110) surfaces, the steps distribute under the influence of step-step interactions. The terrace width distributions indicate an additional oscillatory component besides an l^{-2} interaction term. If the surface is contaminated slightly (quasi-clean), isolated "pinning sites" impede the motion of steps. The interactions between steps push the steps across the pinning site, resulting in a curved step front. When oxygen atoms adsorb on stepped Ag(110), a dramatic change in surface morphology occurs. The surface separates into two distinct phases--step bunches and large terraces (facets). The orientational instability is closely related to the linear "added-row" structure of the oxygen overlayer, as the long O chains push steps into bunches. The O chains do not push the steps effectively when O chains orient perpendicular to steps, and the faceting proceeds through nucleation. If the O chains orient near parallel to steps, however, O chains push the steps easily and the faceting proceeds through spinodal decomposition. To understand the mass transport during faceting, I quantify the thermal step fluctuations by employing a Langevin statistical analysis. The mass transport mechanism at the step edge is shown to be by atomic exchange between steps and terraces, making the step an effective source or sink for Ag adatoms. This Ag source also proves essential in O overlayer formation, since both Ag and O atoms are incorporated into the "added -row" overlayer structure. Because an Ag source must be found during the adlayer formation, I show the surface morphology is sensitive to oxygen dosing pressure. Above a critical O pressure of 10^{-5} mbar, vacancy islands on terraces provide a second source of Ag

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

    NASA Astrophysics Data System (ADS)

    Adam, Fatih Alperen

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

  8. Examination of Behavior of Fresh Concrete Under Pressure

    NASA Astrophysics Data System (ADS)

    Yücel, K. T.

    2012-05-01

    Transporting fresh concrete constitutes a significant part of the production process. Transferring ready-mixed concrete on-site is done using concrete pumps. Recent developments in concrete technology, and in mineral and chemical additives, have resulted in new developments in pumping techniques and the use of different concrete mixtures and equipment. These developments required further knowledge of the behavior of fresh concrete under pressure. Two criteria were determined for the pumpability of concrete: the power required to move the concrete or of the repulsive force; and the cohesion of the fresh concrete. It would be insufficient to relate pumpability to these two criteria; the values of segregation pressure, diffusion ability, water retention capacity, and side friction of the mixture are significant parameters in ensuring that concrete is pumped freely along the pipe. To solve the pumpability problem, friction stresses should be determined as a function of the linear pressure gradient, the pressure leading to segregation of the fresh concrete should be determined, and tests for the bleeding of concrete under pressure should be examined. The scope of the research is the examination of the behavior of fresh concrete under pressure. To determine the segregation pressures, a test apparatus was designed for the bleeding of concrete under pressure. The main purpose of the study is to determine whether the concrete can be pumped easily and whether it will lose its cohesion during the pumping, based on tests of concrete workability and bleeding of concrete under pressure.

  9. Concrete Paving Blocks: An Overview

    DTIC Science & Technology

    1993-08-11

    REPORT TYPE AND DATES COVERED 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS C)gErE PAVING’ S0C4(S: At4N OVERVIEW 6. AUTHOR(S) tlCHfL K. AM U EUT5Av-T) C1 VI L...C13p c~cTE ePvI4G 3LCas PA\\I~f1EpJT W~f 40MIANCE (0~ PA ;Fs eAVrEENT DES 1I6M PVEA Y~~f~F C _S a~ 9L CONCRETE PAVING BLODCKS AN OVERVIEW by LT MCHAEL K...papers are published elsewhere. This report examines CBP’s from several perspectives in order to provide an overview of this alternative pavement

  10. Immobilization of iodine in concrete

    DOEpatents

    Clark, Walter E.; Thompson, Clarence T.

    1977-04-12

    A method for immobilizing fission product radioactive iodine recovered from irradiated nuclear fuel comprises combining material comprising water, Portland cement and about 3-20 wt. % iodine as Ba(IO.sub.3).sub.2 to provide a fluid mixture and allowing the fluid mixture to harden, said Ba(IO.sub.3).sub.2 comprising said radioactive iodine. An article for solid waste disposal comprises concrete prepared by this method. BACKGROUND OF THE INVENTION This invention was made in the course of, or under a contract with the Energy Research and Development Administration. It relates in general to reactor waste solidification and more specifically to the immobilization of fission product radioactive iodine recovered from irradiated nuclear fuel for underground storage.

  11. Lunar cement and lunar concrete

    NASA Technical Reports Server (NTRS)

    Lin, T. D.

    1991-01-01

    Results of a study to investigate methods of producing cements from lunar materials are presented. A chemical process and a differential volatilization process to enrich lime content in selected lunar materials were identified. One new cement made from lime and anorthite developed compressive strengths of 39 Mpa (5500 psi) for 1 inch paste cubes. The second, a hypothetical composition based on differential volatilization of basalt, formed a mineral glass which was activated with an alkaline additive. The 1 inch paste cubes, cured at 100C and 100 percent humidity, developed compressive strengths in excess of 49 Mpa (7100 psi). Also discussed are tests made with Apollo 16 lunar soil and an ongoing investigation of a proposed dry mix/steam injection procedure for casting concrete on the Moon.

  12. SA-based concrete seismic stress monitoring: a case study for normal strength concrete

    NASA Astrophysics Data System (ADS)

    Hou, S.; Zhang, H. B.; Ou, J. P.

    2016-09-01

    The stress history of concrete structures that have survived an earthquake can serve as a critical index to evaluate the health of the structure. There are currently few reliable monitoring methods to assess concrete stress after a seismic event. Piezoelectric-based smart aggregate (SA) provides an innovative experimental approach to monitor stress on concrete. The principle of SA-based concrete seismic stress monitoring is based on the assumption that concrete stress can be reliably predicted by the average output voltages of limited SAs with an acceptable margin of error. In this study, the meso-scale randomness of concrete was evaluated throughout the overall stress range of concrete and the influence of different load paths was considered. Four cylindrical specimens of normal strength concrete were embedded with a total of 24 SAs. The SA output sensitivity curve in the paths of loading-unloading with different amplitudes and monotonic loading up to failure was obtained. Monitoring errors were analyzed during pre- and post-peak stages from the experimental results. This research suggests that SA-based concrete seismic stress monitoring for normal strength concrete is reliable.

  13. Modeling the electrokinetic decontamination of concrete

    SciTech Connect

    Harris, M.T.; DePaoli, D.W.; Ally, M.R.

    1997-01-01

    The decontamination of concrete is a major concern in many Department of (DOE) facilities. Numerous techniques (abrasive methods, manual methods, ultrasonics, concrete surface layer removal, chemical extraction methods, etc.) have been used to remove radioactive contamination from the surface of concrete. Recently, processes that are based on electrokinetic phenomena have been developed to decontaminate concrete. Electrokinetic decontamination has been shown to remove from 70 to over 90% of the surface radioactivity. To evaluate and improve the electrokinetic processes, a model has been developed to simulate the transport of ionic radionuclei constituents through the pores of concrete and into the anolyte and catholyte. The model takes into account the adsorption and desorption kinetics of the radionuclei from the pore walls, and ion transport by electro-osmosis, electromigration, and diffusion. A numerical technique, orthogonal collocation, is used to simultaneously solve the governing convective diffusion equations for a porous concrete slab and the current density equation. This paper presents the theoretical framework of the model and the results from the computation of the dynamics of ion transport during electrokinetic treatment of concrete. The simulation results are in good agreement with experimental data.

  14. Controlling chloride ions diffusion in concrete.

    PubMed

    Zeng, Lunwu; Song, Runxia

    2013-11-28

    The corrosion of steel in concrete is mainly due to the chemical reaction between the chloride ions and iron ions. Indeed, this is a serious threaten for reinforced concrete structure, especially for the reinforced concrete structure in the sea. So it is urgent and important to protect concrete against chloride ions corrosion. In this work, we report multilayer concrete can cloak chloride ions. We formulated five kinds of concrete A, B, C, D and E, which are made of different proportion of cement, sand and glue, and fabricated six-layer (ABACAD) cylinder diffusion cloak and background media E. The simulation results show that the six-layer mass diffusion cloak can protect concrete against chloride ions penetration, while the experiment results show that the concentration gradients are parallel and equal outside the outer circle in the diffusion flux lines, the iso-concentration lines are parallel outside the outer circle, and the concentration gradients in the inner circle are smaller than those outside the outer circle.

  15. Microstructure of high-strength foam concrete

    SciTech Connect

    Just, A.; Middendorf, B.

    2009-07-15

    Foam concretes are divided into two groups: on the one hand the physically foamed concrete is mixed in fast rotating pug mill mixers by using foaming agents. This concrete cures under atmospheric conditions. On the other hand the autoclaved aerated concrete is chemically foamed by adding aluminium powder. Afterwards it is cured in a saturated steam atmosphere. New alternatives for the application of foam concretes arise from the combination of chemical foaming and air curing in manufacturing processes. These foam concretes are new and innovative building materials with interesting properties: low mass density and high strength. Responsible for these properties are the macro-, meso- and microporosity. Macropores are created by adding aluminium powder in different volumes and with different particle size distributions. However, the microstructure of the cement matrix is affected by meso- and micropores. In addition, the matrix of the hardened cement paste can be optimized by the specific use of chemical additives for concrete. The influence of aluminium powder and chemical additives on the properties of the microstructure of the hardened cement matrices were investigated by using petrographic microscopy as well as scanning electron microscopy.

  16. Nondestructive evaluation of thick concrete structures

    NASA Astrophysics Data System (ADS)

    Clayton, Dwight A.

    2015-03-01

    Concrete has been used in the construction of nuclear power plants (NPPs) due to three primary properties: its low cost, structural strength, and ability to shield radiation. Examples of concrete structures important to the safety of Light Water Reactor (LWR) plants include the containment building, spent fuel pool, and cooling towers. Use in these structures has made concrete's long-term performance crucial for the safe operation of commercial NPPs. Extending LWR operating period to 60 years and beyond will likely increase susceptibility and severity of known forms of degradation. New mechanisms of materials degradation are also possible. This creates the need to be able to nondestructively evaluate the current subsurface concrete condition of aging concrete material in NPP structures. The size and complexity of NPP containment structures and heterogeneity of Portland cement concrete make characterization of the degradation extent a difficult task. Specially designed and fabricated test specimens can provide realistic flaws that are similar to actual flaws in terms of how they interact with a particular nondestructive evaluation (NDE) technique. Artificial test blocks allow the isolation of certain testing problems as well as the variation of certain parameters. Representative large heavily reinforced concrete specimens would allow for comparative testing to evaluate the state-of-the-art NDE in this area and to identify additional developments necessary to address the challenges potentially found in NPPs.

  17. Self-cleaning geopolymer concrete - A review

    NASA Astrophysics Data System (ADS)

    Norsaffirah Zailan, Siti; Mahmed, Norsuria; Bakri Abdullah, Mohd Mustafa Al; Sandu, Andrei Victor

    2016-06-01

    Concrete is the most widely used construction materials for building technology. However, cement production releases high amounts of carbon dioxide (CO2) to the atmosphere that leads to increasing the global warming. Thus, an alternative, environmental friendly construction material such as geopolymer concrete has been developed. Geopolymer concrete applies greener alternative binder, which is an innovative construction material that replaces the Portland cement. This technology introduced nano-particles such as nanoclay into the cement paste in order to improve their mechanical properties. The concrete materials also have been developed to be functioned as self-cleaning construction materials. The self-cleaning properties of the concrete are induced by introducing the photocatalytic materials such as titania (TiO2) and zinc oxide (ZnO). Self-cleaning concrete that contains those photocatalysts will be energized by ultraviolet (UV) radiation and accelerates the decomposition of organic particulates. Thus, the cleanliness of the building surfaces can be maintained and the air surrounding air pollution can be reduced. This paper briefly reviews about self-cleaning concrete.

  18. MR cone-beam CT fusion image overlay for fluoroscopically guided percutaneous biopsies in pediatric patients.

    PubMed

    Thakor, Avnesh S; Patel, Premal A; Gu, Richard; Rea, Vanessa; Amaral, Joao; Connolly, Bairbre L

    2016-03-01

    Lesions only visible on magnetic resonance (MR) imaging cannot easily be targeted for image-guided biopsy using ultrasound or X-rays but instead require MR guidance with MR-compatible needles and long procedure times (acquisition of multiple MR sequences). We developed an alternative method for performing these difficult biopsies in a standard interventional suite, by fusing MR with cone-beam CT images. The MR cone-beam CT fusion image is then used as an overlay to guide a biopsy needle to the target area under live fluoroscopic guidance. Advantages of this technique include (i) the ability for it to be performed in a conventional interventional suite, (ii) three-dimensional planning of the needle trajectory using cross-sectional imaging, (iii) real-time fluoroscopic guidance for needle trajectory correction and (iv) targeting within heterogeneous lesions based on MR signal characteristics to maximize the potential biopsy yield.

  19. Digital overlay of cartographic information on Landsat MSS data for soil surveys

    NASA Technical Reports Server (NTRS)

    Imhoff, M. L.; Irons, J. R.; Petersen, G. W.; Sykes, S. G.

    1982-01-01

    Cartographic soils data were digitized, spatially registered, and merged with processed Landsat image data. The Landsat Multispectral Scanner Subsystem (MSS) image data were used to generate a thematic map representing different soil surface characteristics and an enhanced image. The thematic map was generated using supervised and unsupervised classification procedures. The enhanced image was generated by performing a linear contrast stretch on data altered by a principal components transformation. Although both procedures yielded images useful for soil unit delineation, image enhancement was determined to be more suitable because it was more expedient and inexpensive. Enhanced images cost $0.06 per hectare, spectral classifications cost $0.08 per hectare. The overlay of cartographic data on Landsat data facilitates comparisons between the various processing methods used for soil unit boundary determination, delineation, and verification. This technique also provides for accurate and expedient spatial referencing for field observations and cartographic correlation.

  20. CFD-Predicted Tile Heating Bump Factors Due to Tile Overlay Repairs

    NASA Technical Reports Server (NTRS)

    Lessard, Victor R.

    2006-01-01

    A Computational Fluid Dynamics investigation of the Orbiter's Tile Overlay Repair (TOR) is performed to assess the aeroheating Damage Assessment Team's (DAT) existing heating correlation method for protuberance interference heating on the surrounding thermal protection system. Aerothermodynamic heating analyses are performed for TORs at the design reference damage locations body points 1800 and 1075 for a Mach 17.9 and a=39deg STS-107 flight trajectory point with laminar flow. Six different cases are considered. The computed peak heating bump factor on the surrounding tiles are below the DAT's heating bump factor values for smooth tile cases. However, for the uneven tiles cases the peak interference heating is shown to be considerably higher than the existing correlation prediction.

  1. Validation system of MR image overlay and other needle insertion techniques.

    PubMed

    Fischer, Gregory S; Dyer, Eva; Csoma, Csaba; Deguet, Anton; Fichtinger, Gabor

    2007-01-01

    In order to develop accurate and effective augmented reality (AR) systems used in MR and CT guided needle placement procedures, a comparative validation environment is necessary. Clinical equipment is prohibitively expensive and often inadequate for precise measurement. Therefore, we have developed a laboratory validation system for measuring operator performance using different assistance techniques. Electromagnetically tracked needles are registered with the preoperative plan to measure placement accuracy and the insertion path. The validation system provides an independent measure of accuracy that can be applied to varying methods of assistance ranging from augmented reality guidance methods to tracked navigation systems and autonomous robots. In preliminary studies, this validation system is used to evaluate the performance of the image overlay, bi-plane laser guide, and traditional freehand techniques.

  2. Study on overlay AEI-ADI shift on contact layer of advanced technology node

    NASA Astrophysics Data System (ADS)

    Deng, Guogui; Hao, Jingan; Xiao, Lihong; Xing, Bin; Jiang, Yuntao; He, Kaiting; Zhang, Qiang; He, Weiming; Liu, Chang; Lin, Yi-Shih; Wu, Qiang; Shi, Xuelong

    2016-03-01

    In this paper, we present a study on the overlay (OVL) shift issue in contact (CT) layer aligned to poly-silicon (short as poly) layer (prior layer) in an advanced technology node [1, 2]. We have showed the wafer level OVL AEI-ADI shift (AEI: After Etch Inspection; ADI: After Developing Inspection; AEI-ADI: AEI minus ADI). Within the shot level map, there exists a center-edge difference. The OVL focus subtraction map can well match the OVL AEI-ADI shift map. Investigation into this interesting correlation finally leads to the conclusion of PR tilt. The film stress of the thick hard mask is responsible for the PR tilt. The method of OVL focus subtraction can therefore be a powerful and convenient tool to represent the OVL mark profile. It is also important to take into account the film deposition when investigating OVL AEI-ADI shift.

  3. Secret Forwarding of Events over Distributed Publish/Subscribe Overlay Network.

    PubMed

    Yoon, Young; Kim, Beom Heyn

    2016-01-01

    Publish/subscribe is a communication paradigm where loosely-coupled clients communicate in an asynchronous fashion. Publish/subscribe supports the flexible development of large-scale, event-driven and ubiquitous systems. Publish/subscribe is prevalent in a number of application domains such as social networking, distributed business processes and real-time mission-critical systems. Many publish/subscribe applications are sensitive to message loss and violation of privacy. To overcome such issues, we propose a novel method of using secret sharing and replication techniques. This is to reliably and confidentially deliver decryption keys along with encrypted publications even under the presence of several Byzantine brokers across publish/subscribe overlay networks. We also propose a framework for dynamically and strategically allocating broker replicas based on flexibly definable criteria for reliability and performance. Moreover, a thorough evaluation is done through a case study on social networks using the real trace of interactions among Facebook users.

  4. A comprehensive evaluation of high friction overlay systems on bridge decks in cold climate regions

    NASA Astrophysics Data System (ADS)

    Kostick, Robert D.

    In recent history the Minnesota Department of Transportation has looked to improve the safety of bridge decks by installing high friction overlays (HFO). A comprehensive study researched four different proprietary HFO systems placed on fourteen bridge decks throughout Minnesota. Research was split into three separate tasks: (1) laboratory testing of aggregate properties, (2) field observations and testing, and (3) a comprehensive analysis of crash data investigated crash rates on bridges with HFO systems. Field observations and testing revealed that the use of snowplows quickly abrades HFO systems. Abrasion, among other factors, causes a reduction in surface friction values, and reduces the life of HFO systems. Furthermore, improving crash rate trends cannot be directly correlated to the installation of HFO systems. Research concludes that HFO systems should not be used in Minnesota. Other cold climate transportation agencies should conduct research emulated after this study to assess HFO systems in their jurisdiction.

  5. Optical wafer metrology sensors for process-robust CD and overlay control in semiconductor device manufacturing

    NASA Astrophysics Data System (ADS)

    den Boef, Arie J.

    2016-06-01

    This paper presents three optical wafer metrology sensors that are used in lithography for robustly measuring the shape and position of wafers and device patterns on these wafers. The first two sensors are a level sensor and an alignment sensor that measure, respectively, a wafer height map and a wafer position before a new pattern is printed on the wafer. The third sensor is an optical scatterometer that measures critical dimension-variations and overlay after the resist has been exposed and developed. These sensors have different optical concepts but they share the same challenge that sub-nm precision is required at high throughput on a large variety of processed wafers and in the presence of unknown wafer processing variations. It is the purpose of this paper to explain these challenges in more detail and give an overview of the various solutions that have been introduced over the years to come to process-robust optical wafer metrology.

  6. Secret Forwarding of Events over Distributed Publish/Subscribe Overlay Network

    PubMed Central

    Kim, Beom Heyn

    2016-01-01

    Publish/subscribe is a communication paradigm where loosely-coupled clients communicate in an asynchronous fashion. Publish/subscribe supports the flexible development of large-scale, event-driven and ubiquitous systems. Publish/subscribe is prevalent in a number of application domains such as social networking, distributed business processes and real-time mission-critical systems. Many publish/subscribe applications are sensitive to message loss and violation of privacy. To overcome such issues, we propose a novel method of using secret sharing and replication techniques. This is to reliably and confidentially deliver decryption keys along with encrypted publications even under the presence of several Byzantine brokers across publish/subscribe overlay networks. We also propose a framework for dynamically and strategically allocating broker replicas based on flexibly definable criteria for reliability and performance. Moreover, a thorough evaluation is done through a case study on social networks using the real trace of interactions among Facebook users. PMID:27367610

  7. Key Management Schemes for Peer-to-Peer Multimedia Streaming Overlay Networks

    NASA Astrophysics Data System (ADS)

    Naranjo, J. A. M.; López-Ramos, J. A.; Casado, L. G.

    Key distribution for multimedia live streaming peer-to-peer overlay networks is a field still in its childhood stage. A scheme designed for networks of this kind must seek security and efficiency while keeping in mind the following restrictions: limited bandwidth, continuous playing, great audience size and clients churn. This paper introduces two novel schemes that allow a trade-off between security and efficiency by allowing to dynamically vary the number of levels used in the key hierarchy. These changes are motivated by great variations in audience size, and initiated by decision of the Key Server. Additionally, a comparative study of both is presented, focusing on security and audience size. Results show that larger key hierarchies can supply bigger audiences, but offer less security against statistical attacks. The opposite happens for shorter key hierarchies.

  8. An Efficient, Scalable and Robust P2P Overlay for Autonomic Communication

    NASA Astrophysics Data System (ADS)

    Li, Deng; Liu, Hui; Vasilakos, Athanasios

    The term Autonomic Communication (AC) refers to self-managing systems which are capable of supporting self-configuration, self-healing and self-optimization. However, information reflection and collection, lack of centralized control, non-cooperation and so on are just some of the challenges within AC systems. Since many self-* properties (e.g. selfconfiguration, self-optimization, self-healing, and self-protecting) are achieved by a group of autonomous entities that coordinate in a peer-to-peer (P2P) fashion, it has opened the door to migrating research techniques from P2P systems. P2P's meaning can be better understood with a set of key characteristics similar to AC: Decentralized organization, Self-organizing nature (i.e. adaptability), Resource sharing and aggregation, and Fault-tolerance. However, not all P2P systems are compatible with AC. Unstructured systems are designed more specifically than structured systems for the heterogeneous Internet environment, where the nodes' persistence and availability are not guaranteed. Motivated by the challenges in AC and based on comprehensive analysis of popular P2P applications, three correlative standards for evaluating the compatibility of a P2P system with AC are presented in this chapter. According to these standards, a novel Efficient, Scalable and Robust (ESR) P2P overlay is proposed. Differing from current structured and unstructured, or meshed and tree-like P2P overlay, the ESR is a whole new three dimensional structure to improve the efficiency of routing, while information exchanges take in immediate neighbors with local information to make the system scalable and fault-tolerant. Furthermore, rather than a complex game theory or incentive mechanism, asimple but effective punish mechanism has been presented based on a new ID structure which can guarantee the continuity of each node's record in order to discourage negative behavior on an autonomous environment as AC.

  9. Large-Scale Overlays and Trends: Visually Mining, Panning and Zooming the Observable Universe.

    PubMed

    Luciani, Timothy Basil; Cherinka, Brian; Oliphant, Daniel; Myers, Sean; Wood-Vasey, W Michael; Labrinidis, Alexandros; Marai, G Elisabeta

    2014-07-01

    We introduce a web-based computing infrastructure to assist the visual integration, mining and interactive navigation of large-scale astronomy observations. Following an analysis of the application domain, we design a client-server architecture to fetch distributed image data and to partition local data into a spatial index structure that allows prefix-matching of spatial objects. In conjunction with hardware-accelerated pixel-based overlays and an online cross-registration pipeline, this approach allows the fetching, displaying, panning and zooming of gigabit panoramas of the sky in real time. To further facilitate the integration and mining of spatial and non-spatial data, we introduce interactive trend images-compact visual representations for identifying outlier objects and for studying trends within large collections of spatial objects of a given class. In a demonstration, images from three sky surveys (SDSS, FIRST and simulated LSST results) are cross-registered and integrated as overlays, allowing cross-spectrum analysis of astronomy observations. Trend images are interactively generated from catalog data and used to visually mine astronomy observations of similar type. The front-end of the infrastructure uses the web technologies WebGL and HTML5 to enable cross-platform, web-based functionality. Our approach attains interactive rendering framerates; its power and flexibility enables it to serve the needs of the astronomy community. Evaluation on three case studies, as well as feedback from domain experts emphasize the benefits of this visual approach to the observational astronomy field; and its potential benefits to large scale geospatial visualization in general.

  10. Overlay accuracy on a flexible web with a roll printing process based on a roll-to-roll system.

    PubMed

    Chang, Jaehyuk; Lee, Sunggun; Lee, Ki Beom; Lee, Seungjun; Cho, Young Tae; Seo, Jungwoo; Lee, Sukwon; Jo, Gugrae; Lee, Ki-yong; Kong, Hyang-Shik; Kwon, Sin

    2015-05-01

    For high-quality flexible devices from printing processes based on Roll-to-Roll (R2R) systems, overlay alignment during the patterning of each functional layer poses a major challenge. The reason is because flexible substrates have a relatively low stiffness compared with rigid substrates, and they are easily deformed during web handling in the R2R system. To achieve a high overlay accuracy for a flexible substrate, it is important not only to develop web handling modules (such as web guiding, tension control, winding, and unwinding) and a precise printing tool but also to control the synchronization of each unit in the total system. A R2R web handling system and reverse offset printing process were developed in this work, and an overlay between the 1st and 2nd layers of ±5μm on a 500 mm-wide film was achieved at a σ level of 2.4 and 2.8 (x and y directions, respectively) in a continuous R2R printing process. This paper presents the components and mechanisms used in reverse offset printing based on a R2R system and the printing results including positioning accuracy and overlay alignment accuracy.

  11. Overlay accuracy on a flexible web with a roll printing process based on a roll-to-roll system

    NASA Astrophysics Data System (ADS)

    Chang, Jaehyuk; Lee, Sunggun; Lee, Ki Beom; Lee, Seungjun; Cho, Young Tae; Seo, Jungwoo; Lee, Sukwon; Jo, Gugrae; Lee, Ki-yong; Kong, Hyang-Shik; Kwon, Sin

    2015-05-01

    For high-quality flexible devices from printing processes based on Roll-to-Roll (R2R) systems, overlay alignment during the patterning of each functional layer poses a major challenge. The reason is because flexible substrates have a relatively low stiffness compared with rigid substrates, and they are easily deformed during web handling in the R2R system. To achieve a high overlay accuracy for a flexible substrate, it is important not only to develop web handling modules (such as web guiding, tension control, winding, and unwinding) and a precise printing tool but also to control the synchronization of each unit in the total system. A R2R web handling system and reverse offset printing process were developed in this work, and an overlay between the 1st and 2nd layers of ±5μm on a 500 mm-wide film was achieved at a σ level of 2.4 and 2.8 (x and y directions, respectively) in a continuous R2R printing process. This paper presents the components and mechanisms used in reverse offset printing based on a R2R system and the printing results including positioning accuracy and overlay alignment accuracy.

  12. Evaluation of iron aluminide weld overlays for erosion - corrosion resistant boiler tube coatings in low NO{sub x} boilers

    SciTech Connect

    DuPont, J.N.; Banovic, S.W.; Marder, A.R.

    1996-08-01

    Low NOx burners are being installed in many fossil fired power plants in order to comply with new Clean Air Regulations. Due to the operating characteristics of these burners, boiler tube sulfidation corrosion is often enhanced and premature tube failures can occur. Failures due to oxidation and solid particle erosion are also a concern. A program was initiated in early 1996 to evaluate the use of iron aluminide weld overlays for erosion/corrosion protection of boiler tubes in Low NOx boilers. Composite iron/aluminum wires will be used with the Gas Metal Arc Welding (GMAW) process to prepare overlays on boiler tubes steels with aluminum contents from 8 to 16wt%. The weldability of the composite wires will be evaluated as a function of chemical composition and welding parameters. The effect of overlay composition on corrosion (oxidation and sulfidation) and solid particle erosion will also be evaluated. The laboratory studies will be complemented by field exposures of both iron aluminide weld overlays and co-extruded tubing under actual boiler conditions.

  13. Investigation of electrokinetic decontamination of concrete

    SciTech Connect

    DePaoli, D.W.; Harris, M.T.; Morgan, I.L.; Ally, M.R.

    1995-12-31

    Experiments have been conducted to investigate the capabilities of electrokinetic decontamination of concrete. Batch equilibration studies have determined that the loading of cesium and strontium on concrete may be decreased using electrolyte solutions containing competing cations, while solubilization of uranium and cobalt, that precipitate at high pH, will require lixiviants containing complexing agents. Dynamic electrokinetic experiments showed greater mobility of cesium than strontium, while some positive results were obtained for the transport of cobalt through concrete using EDTA and for uranium using carbonate.

  14. Development of refractory concrete for extreme conditions

    NASA Astrophysics Data System (ADS)

    Pundiene, I.; Antonovich, V.; Stonys, R.; Demidova-Buiziniene, I.

    2011-12-01

    Comparative analysis is provided for the properties of medium-cement refractory concrete with microsilica based on mullite filler in relation to different type of deflocculant. The effect of different deflocculants on refractory concrete structure formation, hydration, rheology, strength and heat resistance is discussed. Corrosion resistance test, determined that samples with hybrid deflocculant showed better resistance for slag penetration than samples with only the sodium tripolyphosphate or polycarboxylate ether deflocculant. Moreover, a composition of hybrid deflocculant let to control the rate of the hydration process and to get features of refractory refractory concrete.

  15. Reusing recycled aggregates in structural concrete

    NASA Astrophysics Data System (ADS)

    Kou, Shicong

    The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental

  16. Molecular Survey of Concrete Sewer Biofilm Microbial Communities

    EPA Science Inventory

    Although bacteria are implicated in deteriorating concrete structures, there is very little information on the composition of concrete microbial communities. To this end, we studied different concrete biofilms by performing sequence analysis of 16S rDNA concrete clone libraries. ...

  17. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 8 2014-07-01 2014-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  18. 76 FR 34890 - Track Safety Standards; Concrete Crossties

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-15

    ... Federal Railroad Administration 49 CFR Part 213 RIN 2130-AC01 Track Safety Standards; Concrete Crossties... mandates specific requirements for effective concrete crossties, for rail fastening systems connected to concrete crossties, and for automated inspections of track constructed with concrete crossties. The...

  19. 76 FR 55819 - Track Safety Standards; Concrete Crossties

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-09

    ... Federal Railroad Administration 49 CFR Part 213 RIN 2130-AC35 Track Safety Standards; Concrete Crossties... concrete crossties, for rail fastening systems connected to concrete crossties, and for automated inspections of track constructed with concrete crossties. This document amends and clarifies the final...

  20. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 8 2011-07-01 2011-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  1. 76 FR 18073 - Track Safety Standards; Concrete Crossties

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-01

    ... Federal Railroad Administration 49 CFR Part 213 RIN 2130-AC01 Track Safety Standards; Concrete Crossties... over track constructed with concrete crossties. In particular, FRA is mandating specific requirements for effective concrete crossties, for rail fastening systems connected to concrete crossties, and...

  2. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  3. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  4. 29 CFR 1926.704 - Requirements for precast concrete.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 8 2013-07-01 2013-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  5. Mechanical and Physical Properties of Polyester Polymer Concrete Using Recycled Aggregates from Concrete Sleepers

    PubMed Central

    Carrión, Francisco; Montalbán, Laura; Real, Julia I.

    2014-01-01

    Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate), and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strength, flexural strength, modulus of elasticity, density, and water absorption) was analyzed based on the modification of different variables: nature of the recycled aggregates, resin contents (11 wt%, 12 wt%, and 13 wt%), and particle-size distributions of microfillers used. The results show the influence of these variables on mechanical performance of polymer concrete. Compressive and flexural strength of recycled polymer concrete were improved by increasing amount of polyester resin and by optimizing the particle-size distribution of the microfillers. Besides, the results show the feasibility of developing a polymer concrete with excellent mechanical behavior. PMID:25243213

  6. Mechanical and physical properties of polyester polymer concrete using recycled aggregates from concrete sleepers.

    PubMed

    Carrión, Francisco; Montalbán, Laura; Real, Julia I; Real, Teresa

    2014-01-01

    Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate), and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strength, flexural strength, modulus of elasticity, density, and water absorption) was analyzed based on the modification of different variables: nature of the recycled aggregates, resin contents (11 wt%, 12 wt%, and 13 wt%), and particle-size distributions of microfillers used. The results show the influence of these variables on mechanical performance of polymer concrete. Compressive and flexural strength of recycled polymer concrete were improved by increasing amount of polyester resin and by optimizing the particle-size distribution of the microfillers. Besides, the results show the feasibility of developing a polymer concrete with excellent mechanical behavior.

  7. A Facile Surface Passivation of Hematite Photoanodes with TiO2 Overlayers for Efficient Solar Water Splitting.

    PubMed

    Ahmed, Mahmoud G; Kretschmer, Imme E; Kandiel, Tarek A; Ahmed, Amira Y; Rashwan, Farouk A; Bahnemann, Detlef W

    2015-11-04

    The surface modification of semiconductor photoelectrodes with passivation overlayers has recently attracted great attention as an effective strategy to improve the charge-separation and charge-transfer processes across semiconductor-liquid interfaces. It is usually carried out by employing the sophisticated atomic layer deposition technique, which relies on reactive and expensive metalorganic compounds and vacuum processing, both of which are significant obstacles toward large-scale applications. In this paper, a facile water-based solution method has been developed for the modification of nanostructured hematite photoanode with TiO2 overlayers using a water-soluble titanium complex (i.e., titanium bis(ammonium lactate) dihydroxide, TALH). The thus-fabricated nanostructured hematite photoanodes have been characterized by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Photoelectrochemical measurements indicated that a nanostructured hematite photoanodes modified with a TiO2 overlayer exhibited a photocurrent response ca. 4.5 times higher (i.e., 1.2 mA cm(-2) vs RHE) than that obtained on the bare hematite photoanode (i.e., 0.27 mA cm(-2) vs RHE) measured under standard illumination conditions. Moreover, a cathodic shift of ca. 190 mV in the water oxidation onset potential was achieved. These results are discussed and explored on the basis of steady-state polarization, transient photocurrent response, open-circuit potential, intensity-modulated photocurrent spectroscopy, and impedance spectroscopy measurements. It is concluded that the TiO2 overlayer passivates the surface states and suppresses the surface electron-hole recombination, thus increasing the generated photovoltage and the band bending. The present method for the hematite electrode modification with a TiO2 overlayer is effective and simple and might find broad applications in the development of stable and high-performance photoelectrodes.

  8. Exploring Floating Concrete and Beam Design.

    ERIC Educational Resources Information Center

    Snell, Billie G.; Snell, Luke M.

    2002-01-01

    Presents two construction activities that address both state and federal science standards and encourage students to consider career options in mathematics and science. Includes floating concrete and paper bridge activities. (YDS)

  9. Laboratory constitutive characterization of cellular concrete.

    SciTech Connect

    Hardy, Robert Douglas; Lee, Moo Yul; Bronowski, David R.

    2004-03-01

    To establish mechanical material properties of cellular concrete mixes, a series of quasi-static, compression and tension tests have been completed. This report summarizes the test methods, set-up, relevant observations, and results from the constitutive experimental efforts. Results from the uniaxial and triaxial compression tests established failure criteria for the cellular concrete in terms of stress invariants I{sub 1} and J{sub 2}. {radical}J{sub 2} (MPa) = 297.2 - 278.7 exp{sup -0.000455 I}{sub 1}{sup (MPa)} for the 90-pcf concrete {radical}J{sub 2} (MPa) = 211.4 - 204.2 exp {sup -0.000628 I}{sub 1}{sup (MPa)} for the 60-pcf concrete

  10. Seismic safety of high concrete dams

    NASA Astrophysics Data System (ADS)

    Chen, Houqun

    2014-08-01

    China is a country of high seismicity with many hydropower resources. Recently, a series of high arch dams have either been completed or are being constructed in seismic regions, of which most are concrete dams. The evaluation of seismic safety often becomes a critical problem in dam design. In this paper, a brief introduction to major progress in the research on seismic aspects of large concrete dams, conducted mainly at the Institute of Water Resources and Hydropower Research (IWHR) during the past 60 years, is presented. The dam site-specific ground motion input, improved response analysis, dynamic model test verification, field experiment investigations, dynamic behavior of dam concrete, and seismic monitoring and observation are described. Methods to prevent collapse of high concrete dams under maximum credible earthquakes are discussed.

  11. Pentek concrete scabbling system: Baseline report

    SciTech Connect

    1997-07-31

    The Pentek scabbling technology was tested at Florida International University (FIU) and is being evaluated as a baseline technology. This report evaluates it for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The Pentek concrete scabbling system consisted of the MOOSE{reg_sign}, SQUIRREL{reg_sign}-I, and SQUIRREL{reg_sign}-III scabblers. The scabblers are designed to scarify concrete floors and slabs using cross-section, tungsten carbide tipped bits. The bits are designed to remove concrete in 318 inch increments. The bits are either 9-tooth or demolition type. The scabblers are used with a vacuum system designed to collect and filter the concrete dust and contamination that is removed from the surface. The safety and health evaluation during the human factors assessment focused on two main areas: noise and dust.

  12. Sequestration of CO2 by concrete carbonation.

    PubMed

    Galan, Isabel; Andrade, Carmen; Mora, Pedro; Sanjuan, Miguel A

    2010-04-15

    Carbonation of reinforced concrete is one of the causes of corrosion, but it is also a way to sequester CO2. The characteristics of the concrete cover should ensure alkaline protection for the steel bars but should also be able to combine CO2 to a certain depth. This work attempts to advance the knowledge of the carbon footprint of cement. As it is one of the most commonly used materials worldwide, it is very important to assess its impact on the environment. In order to quantify the capacity of cement based materials to combine CO2 by means of the reaction with hydrated phases to produce calcium carbonate, Thermogravimetry and the phenolphthalein indicator have been used to characterize several cement pastes and concretes exposed to different environments. The combined effect of the main variables involved in this process is discussed. The moisture content of the concrete seems to be the most influential parameter.

  13. Concrete "Waffle" Provides Laser Beam Accuracy

    ERIC Educational Resources Information Center

    Building Design and Construction, 1978

    1978-01-01

    A massive concrete "waffle," riding on a bed of specially treated gravel and sand inside another building, provides the structural rigidity needed by the University of Rochester's Laboratory for Laser Energetics. (Author)

  14. Damage characterization in concrete using diffuse ultrasound

    NASA Astrophysics Data System (ADS)

    Shokouhi, Parisa; Niederleithinger, Ernst

    2012-05-01

    Diffuse ultrasonic measurements were used to characterize the state of stress-induced damage (volumetric microcracking) in concrete specimens. The test specimens were subjected to cycles of stepwise uniaxial compression. At each step, the loading (stress- or strain-controlled) was held constant and a series of ultrasonic measurements parallel and perpendicular to the loading were obtained. Unusually long signals were recorded, so that the diffuse ultrasonic regime tailing the coherent field could be studied. In the diffuse regime, the measured ultrasonic response is a superposition of reflections from scatters within concrete and thus, very sensitive to the changes in concrete microstructure. Using Coda Wave Interferometry (CWI), the evolution of diffuse velocity with the increasing load was monitored. The rate of change in the diffusion velocities was shown to be a good indication of the state of (low to medium intensity) damage in concrete.

  15. Cements for Structural Concrete in Cold Regions.

    DTIC Science & Technology

    1977-10-01

    setting-times than the Vicat test. Once the initial set has been reached, the high alumina cement will gain strength at a very rapid rate. This is not...the concrete becomes more permeable and decreases in strength . Neuman (1960) reports that high alumina cement concrete that has been affected by hot...conversion becomes more rapid and a serious loss of strength occurs which may take some months to develop (Building Research Establishment 1975). HIGH

  16. Variability in properties of Salado Mass Concrete

    SciTech Connect

    Wakeley, L.D.; Harrington, P.T.; Hansen, F.D.

    1995-08-01

    Salado Mass Concrete (SMC) has been developed for use as a seal component in the Waste Isolation Pilot Plant. This concrete is intended to be mixed from pre-bagged materials, have an initial slump of 10 in., and remain pumpable and placeable for two hours after mixing. It is a mass concrete because it will be placed in monoliths large enough that the heat generated during cement hydration has the potential to cause thermal expansion and subsequent cracking, a phenomenon to avoid in the seal system. This report describes effects on concrete properties of changes in ratio of water to cement, batch size, and variations in characteristics of different lots of individual components of the concrete. The research demonstrates that the concrete can be prepared from laboratory-batched or pre-bagged dry materials in batches from 1.5 ft{sup 3} to 5.0 yd{sup 3}, with no chemical admixtures other than the sodium chloride added to improve bonding with the host rock, at a water-to-cement ratio ranging from 0.36 to 0.42. All batches prepared according to established procedures had adequate workability for at least 1.5 hours, and achieved or exceeded the target compressive strength of 4500 psi at 180 days after casting. Portland cement and fly ash from different lots or sources did not have a measurable effect on concrete properties, but variations in a shrinkage-compensating cement used as a component of the concrete did appear to affect workability. A low initial temperature and the water-reducing and set-retarding functions of the salt are critical to meeting target properties.

  17. Evaluation and Repair of Concrete Slabs

    DTIC Science & Technology

    1992-01-01

    is duce a readily flowable concrete that is capable of listed in Table 1. completely filling the formed area. For large surface areas, it may be...Poor compaction, irregular surfaces, expansive soils , and the presence of mud or soft organic material can all result in a yielding subgrade. Again... fill all the spaces around the coarse aggregate. It is easily recognized by voids in the surface where the concrete appears as coarse aggregate

  18. Nonlinear Ultrasonic Evaluation of Concrete Microcracking

    NASA Astrophysics Data System (ADS)

    Woodward, C.; White, K. R.; Jauregui, D. V.; Stauffer, J.

    2004-02-01

    Microcracking is usually associated with most types of concrete deterioration. The nondestructive detection of deterioration in in-situ concrete in its early stages is not practical using current technology. In this project nonlinear ultrasound was used to evaluate the degree of microcracking changes resulting from increasing compression stresses. Second and third harmonic amplitudes were measured and correlated to the degree of microcracking induced in the specimen. These harmonics were found to increase with increasing levels of microcracking.

  19. Spall Repair of Wet Concrete Surfaces

    DTIC Science & Technology

    1990-01-01

    ILE COPY REPAIR, EVALUATION, MAINTENANCE, AND REHABILITATION RESEARCH PROGRAM TECHNICAL REPORT REMR-CS-25 SPALL REPAIR OF WET CONCRETE SURFACES by J...of the number designating technical reports of research published under the Repair, Evaluation. Maintenance. and Rehabilitation (REMR) Research ...Program identify the problem area under which the report was prepared Problem Area Problem Area CS Concrete and Steel Structures EM Electrical and

  20. Modeling of concrete response at high temperature

    SciTech Connect

    Pfeiffer, P.; Marchertas, A.

    1984-01-01

    A rate-type creep law is implemented into the computer code TEMP-STRESS for high temperature concrete analysis. The disposition of temperature, pore pressure and moisture for the particular structure in question is provided as input for the thermo-mechanical code. The loss of moisture from concrete also induces material shrinkage which is accounted for in the analytical model. Examples are given to illustrate the numerical results.

  1. Strain rate effects for spallation of concrete

    NASA Astrophysics Data System (ADS)

    Häussler-Combe, Ulrich; Panteki, Evmorfia; Kühn, Tino

    2015-09-01

    Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The strain rate effect is still an open issue within this context. In particular the question whether it is a material property - which can be covered by rate dependent stress strain relations - or mainly an effect of inertia is still under discussion. Experimental and theoretical investigations of spallation of concrete specimen in a Hopkinson Bar setup may bring some evidence into this question. For this purpose the paper describes the VERD model, a newly developed constitutive law for concrete based on a damage approach with included strain rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to strain rate values but related to physical mechanisms like the retarded movement of water in capillary systems and delayed microcracking. The constitutive law is fully triaxial and implemented into explicit finite element codes for the investigation of a wide range of concrete structures exposed to impact and explosions. The current setup models spallation experiments with concrete specimen [2]. The results of such experiments are mainly related to the dynamic tensile strength and the crack energy of concrete which may be derived from, e.g., the velocity of spalled concrete fragments. The experimental results are compared to the VERD model and two further constitutive laws implemented in LS-Dyna. The results indicate that both viscosity and retarded damage are required for a realistic description of the material behaviour of concrete exposed to high strain effects [3].

  2. Pedogenic Carbonate Concretions in the Russian Chernozem

    SciTech Connect

    Mikhailova, E. A.; Post, C. J.; Magrini-Bair, K.; Castle, J. W.

    2006-12-01

    Pedogenic carbonate concretions are commonly found in grassland soils, but their origin is not fully understood. This study was conducted to determine the radiocarbon age, the stable isotope geochemistry, and chemical composition of carbonate concretions in the Russian Chernozem, one of the typical soils in grasslands. Three sites were sampled: a native grassland field (not cultivated for at least 300 years), an adjacent 50-year continuous fallow field in the V. V. Alekhin Central-Chernozem Biosphere State Reserve in the Kursk region of Russia, and a continuously cropped field in the Experimental Station of the Kursk Institute of Agronomy and Soil Erosion Control. All sampled soils were classified as fine-silty, mixed, frigid Pachic Hapludolls. The mineralogical composition of concretions varies from low-magnesium calcite to pure calcite. The concretion contains 0.05% N, 6.4% C, and has [delta]13C and [delta]18O values of -10.9[per mille sign] (the per mill symbol, parts per thousand) and -7.8[per mille sign], respectively. The outside part of the carbonate concretion is 1909 +/- 40 14C age Before Present (B.P.) compared with 1693 +/- 40 14C age B.P. for the inside part of the same concretion, even though the concretion is found in the C horizon of much older age (10,902 +/- 63 14C age B.P.). Remnants of soil organic matter in concretions are closely associated with the cropped and fallow/plowed soils by pyrolysis molecular beam mass spectrometry.

  3. Repairs to Concrete Port and Harbor Structures

    DTIC Science & Technology

    1991-11-18

    landmarks in the world is the Eddystone lighthouse which was constructed by the British engineer, John Smeaton , in 1756. The lighthouse is situated on the...west outlet of the English Channel and was constructed before the advent of portland cement. Smeaton invented a hydraulic (water-resisting) U lime by...Champion, S., Failure and Repair of Concrete Structures, John Wiley and Sons, New York, 1961 j [38] Gerwick, B. C., "Marine Concrete", Handbook of Ocean

  4. Behavior of Partially Restrained Reinforced Concrete Slabs.

    DTIC Science & Technology

    1986-09-01

    Experimental Deflections and Coupling Forces. ........ 72 3.4 Method of Approximating Support Rotations . . . 76 3.5 Free-Body Diagram Used in Computing...common types of structural elements. Slabs are found in practically every type of structural system, ’ whether steel or concrete, single -story or...Because of the nature of reinforced concrete slabs, accurate evaluations of stresses, strains, and deflections are difficult to make by elasticity

  5. Electromagnetic Metrology on Concrete and Corrosion*

    PubMed Central

    Kim, Sung; Surek, Jack; Baker-Jarvis, James

    2011-01-01

    To augment current methods for the evaluation of reinforcing bar (rebar) corrosion within concrete, we are exploring unique features in the dielectric and magnetic spectra of pure iron oxides and corrosion samples. Any signature needs to be both prominent and consistent in order to identify corrosion within concrete bridge deck or other structures. In order to measure the permittivity and propagation loss through concrete as a function of temperature and humidity, we cut and carefully fitted samples from residential concrete into three different waveguides. We also poured and cured a mortar sample within a waveguide that was later measured after curing 30 days. These measurements were performed from 45 MHz to 12 GHz. Our concrete measurements showed that the coarse granite aggregate that occupied about half the sample volume reduced the electromagnetic propagation loss in comparison to mortar. We also packed ground corrosion samples and commercially available iron-oxide powders into a transmission-line waveguide and found that magnetite and corrosion sample spectra are similar, with a feature between 0.5 GHz and 2 GHz that may prove useful for quantifying corrosion. We also performed reflection (S11) measurements at various corrosion surfaces and in loose powders from 45 MHz to 50 GHz. These results are a first step towards quantifying rebar corrosion in concrete. PMID:26989590

  6. Organic compounds in concrete from demolition works.

    PubMed

    Van Praagh, M; Modin, H; Trygg, J

    2015-11-01

    This study aims to verify the effect of physically removing the outer surface of contaminated concrete on total contents and on potential mobility of pollutants by means of leaching tests. Reclaimed concrete from 3 industrial sites in Sweden were included: A tar impregnated military storage, a military tar track-depot, as well as concrete constructions used for disposing of pesticide production surplus and residues. Solid materials and leachates from batch and column leaching tests were analysed for metals, Cl, F, SO4, DOC and contents of suspected organic compounds (polycyclic aromatic hydrocarbons, PAH, and pesticides/substances for pesticide production such as phenoxy acids, chlorophenols and chlorocresols, respectively). In case of PAH contaminated concrete, results indicate that removing 1 or 5 mm of the surface lead to total concentrations below the Swedish guidelines for recycling of aggregates and soil in groundwork constructions. 3 out of 4 concrete samples contaminated with pesticides fulfilled Swedish guidelines for contaminated soil. Results from batch and column leaching tests indicated, however, that concentrations above environmental quality standards for certain PAH and phenoxy acids, respectively, might occur at site when the crushed concrete is recycled in groundwork constructions. As leaching tests engaged in the study deviated from leaching test standards with a limited number of samples, the potential impact of the leaching tests' equipment on measured PAH and pesticide leachate concentrations has to be evaluated in future work.

  7. Electromagnetic Metrology on Concrete and Corrosion.

    PubMed

    Kim, Sung; Surek, Jack; Baker-Jarvis, James

    2011-01-01

    To augment current methods for the evaluation of reinforcing bar (rebar) corrosion within concrete, we are exploring unique features in the dielectric and magnetic spectra of pure iron oxides and corrosion samples. Any signature needs to be both prominent and consistent in order to identify corrosion within concrete bridge deck or other structures. In order to measure the permittivity and propagation loss through concrete as a function of temperature and humidity, we cut and carefully fitted samples from residential concrete into three different waveguides. We also poured and cured a mortar sample within a waveguide that was later measured after curing 30 days. These measurements were performed from 45 MHz to 12 GHz. Our concrete measurements showed that the coarse granite aggregate that occupied about half the sample volume reduced the electromagnetic propagation loss in comparison to mortar. We also packed ground corrosion samples and commercially available iron-oxide powders into a transmission-line waveguide and found that magnetite and corrosion sample spectra are similar, with a feature between 0.5 GHz and 2 GHz that may prove useful for quantifying corrosion. We also performed reflection (S 11) measurements at various corrosion surfaces and in loose powders from 45 MHz to 50 GHz. These results are a first step towards quantifying rebar corrosion in concrete.

  8. Ultrasonic testing of reactive powder concrete.

    PubMed

    Washer, Glenn; Fuchs, Paul; Graybeal, Benjamin A; Hartmann, Joseph Lawrence

    2004-02-01

    Concrete is a critical material for the construction of infrastructure facilities throughout the world. Traditional concretes consist of cement paste and aggregates ranging in size from 6 to 25 mm that form a heterogeneous material with substantial compressive strength and a very low tensile strength. Steel reinforcement is used to provide tensile strength for reinforced concrete structures and as a composite the material is useful for structural applications. A new material known as reactive powder concrete (RPC) is becoming available. It differs significantly from traditional concrete; RPC has no large aggregates, and contains small steel fibers that provide additional strength and, in some cases, can replace traditional steel reinforcement. Due to its high density and lack of aggregates, ultrasonic inspections at frequencies 10 to 20 times that of traditional concrete inspections are possible. This paper reports on the initial findings of research conducted to determine the applicability of ultrasonic testing techniques for the condition assessment of RPC. Pulse velocities for shear and longitudinal waves and ultrasonic measurement of the modulus of elasticity for RPC are reported. Ultrasonic crack detection for RPC also is investigated.

  9. Beta Bremsstrahlung dose in concrete shielding

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.; Chandrika, B. M.; Rudraswamy, B.; Sankarshan, B. M.

    2012-05-01

    In a nuclear reactor, beta nuclides are released during nuclear reactions. These betas interact with shielding concrete and produces external Bremsstrahlung (EB) radiation. To estimate Bremsstrahlung dose and shield efficiency in concrete, it is essential to know Bremsstrahlung distribution or spectra. The present work formulated a new method to evaluate the EB spectrum and hence Bremsstrahlung dose of beta nuclides (32P, 89Sr, 90Sr-90Y, 90Y, 91Y, 208Tl, 210Bi, 234Pa and 40K) in concrete. The Bremsstrahlung yield of these beta nuclides in concrete is also estimated. The Bremsstrahlung yield in concrete due to 90Sr-90Y is higher than those of other given nuclides. This estimated spectrum is accurate because it is based on more accurate modified atomic number (Zmod) and Seltzer's data, where an electron-electron interaction is also included. Presented data in concrete provide a quick and convenient reference for radiation protection. The present methodology can be used to calculate the Bremsstrahlung dose in nuclear shielding materials. It can be quickly employed to give a first pass dose estimate prior to a more detailed experimental study.

  10. IMPERMEABLE THIN Al{sub 2}O{sub 3} OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

    SciTech Connect

    Scott X. Mao

    2003-12-16

    To improve the hot corrosion resistance of YSZ thermal barrier coatings, a 25 {micro}m and a 2 {micro}m thick Al{sub 2}O{sub 3} overlay were deposited by HVOF thermal spray and by sol-gel coating method, respectively, onto to the surface of YSZ coating. Indenter test was employed to investigate the spalling of YSZ with and without Al{sub 2}O{sub 3} overlay after hot corrosion. The results showed that Al{sub 2}O{sub 3} overlay acted as a barrier against the infiltration of the molten salt into the YSZ coating during exposure, thus significantly reduced the amount of M-phase of ZrO{sub 2} in YSZ coating. However, a thick Al{sub 2}O{sub 3} overlay was harmful for TBC by increasing compressive stress which causes crack and spalling of YSZ coating. As a result, a dense and thin Al{sub 2}O{sub 3} overlay is critical for simultaneously preventing YSZ from hot corrosion and spalling. In the next reporting period, we will measure or calculate the residue stress within Al{sub 2}O{sub 3} overlay and YSZ coating to study the mechanism of effect of Al{sub 2}O{sub 3} overlay on spalling of YSZ coating.

  11. IMPERMEABLE THIN AL2O3 OVERLAY FOR TBC PROTECTION FROM SULFATE AND VANADATE ATTACK IN GAS TURBINES

    SciTech Connect

    Scott X. Mao

    2002-08-31

    In order to improve the hot corrosion resistance of conventional YSZ TBC system, a dense and continues overlay of Al{sub 2}O{sub 3} coating of about 25 {micro}m thick was deposited on the surface of TBC by EB-PVD and high velocity oxy-fuel (HVOF) spray techniques. Hot corrosion tests were carried out on the TBC with and without Al{sub 2}O{sub 3} coating in molten salts mixtures (Na{sub 2}SO{sub 4} + 5% V{sub 2}O5) at 950 C for 10h. The microstructures of TBC and overlay before and after exposure were examined by means of scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDX), X-ray diffraction (XRD) and secondary ion mass spectrometry (SIMS). It has been found that TBC will react with V{sub 2}O{sub 5} to form YVO{sub 4}. A substantial amount of M-phase of ZrO{sub 2} was formed due to the leaching of Y{sub 2}O{sub 3} from YSZ. During hot corrosion test, there were no significant interactions between overlay Al{sub 2}O{sub 3} coating and molten salts. After exposure, the alumina coating, especially produced by HVOF, was still very dense and cover the surface of YSZ, although they had been translated to {alpha}-Al{sub 2}O{sub 3} from original {gamma}-Al{sub 2}O{sub 3}. As a result, Al{sub 2}O{sub 3} overlay coating decreased the penetration of salts into the YSZ and prevented the YSZ from the attack by molten salts containing vanadium. Accordingly, only a few M-phase was formed in YSZ TBC, compared with TBC without overlay coating. The penetration of salts into alumina coating was thought to be through microcracks formed in overlay Al{sub 2}O{sub 3} coating and at the interface between alumina and zirconia due to the presence of tensile stress in the alumina coating. In the next year, we will study the mechanisms of cracking of the overlay Al{sub 2}O{sub 3} layer. The hot corrosion test of TBC with EB-PVD deposited Al{sub 2}O{sub 3} coating will be again performed. However before hot corrosion tests, the post-annealing will be carried out in

  12. Moisture Transport Through Sprayed Concrete Tunnel Linings

    NASA Astrophysics Data System (ADS)

    Holter, Karl Gunnar; Geving, Stig

    2016-01-01

    Waterproofing of permanent sprayed concrete tunnel linings with sprayed membranes in a continuous sandwich structure has been attempted since 2000 and has seen increased use in some countries. The main function of a sprayed membrane from a waterproofing perspective is to provide crack bridging and hence prevent flow of liquid water into the tunnel through cracks and imperfections in the concrete material. However, moisture can migrate through the concrete and EVA-based membrane materials by capillary and vapor diffusion mechanisms. These moisture transport mechanisms can have an influence on the degree of saturation, and may influence the pore pressures in the concrete material as well as risk of freeze-thaw damage of the concrete and membrane. The paper describes a detailed study of moisture transport material parameters, moisture condition in tunnel linings and climatic conditions tunnels in hard rock in Norway. These data have been included in a hygrothermal simulation model in the software WUFI for moisture transport to substantiate moisture transport and long-term effects on saturation of the concrete and membrane material. The findings suggest that EVA-based membranes exhibit significant water absorption and vapor transport properties although they are impermeable to liquid water flow. State-of-the-art sprayed concrete material applied with the wet mix method exhibits very low hydraulic conductivities, lower than 10-14 m/s, thus saturated conductive water flow is a very unlikely dominant transport mechanism. Moisture transport through the lining structure by capillary flow and vapor diffusion are calculated to approximately 3 cm3/m2 per day for lining thicknesses in the range of 25-35 cm and seasonal Nordic climate variations. The calculated moisture contents in the tunnel linings from the hygrothermal simulations are largely in agreement with the measured moisture contents in the tunnel linings. The findings also indicate that the concrete material exhibits

  13. Curvature ductility of reinforced and prestressed concrete columns

    SciTech Connect

    Suprenant, B.A.

    1984-01-01

    Engineers are concerned with the survival of reinforced and prestressed concrete columns during earthquakes. The prediction of column survival can be deduced from moment-curvature curves of the column section. An analytical approach is incorporated into a computer model. The computer program is based on assumed stress-strain relations for confined and unconfined concrete, nonprestressed and prestressing steel. The results of studies on reinforced and prestressed concrete columns indicate that reinforced concrete columns may be designed to resist earthquakes, while prestressed concrete columns may not. The initial reduction in moment capacity, after concrete cover spalling, of a prestressed concrete column could be as much as 50%. Analyses indicate that the bond between concrete and prestressing strand after concrete cover spalling is not critical.

  14. Concrete shaver. Innovative technology summary report

    SciTech Connect

    1998-12-01

    The US Department of Energy (DOE) is in the process of decontamination and decommissioning (D and D) for many of its nuclear facilities throughout the United States. These facilities must be dismantled and the demolition waste sized into manageable pieces for handling and disposal. The facilities undergoing D and D are typically chemically and/or radiologically contaminated. To facilitate this work, DOE requires a tool capable of removing the surface of radiologically contaminated concrete floors. Operating requirements for the tool include simple and economical operation, the capability of operating in ambient temperatures from 3 C to 40 C (37 F to 104 F), and the ability to be easily decontaminated. The tool also must be safe for workers. The Marcrist Industries Limited concrete shaver is an electrically driven, self-propelled concrete and coating removal system. This technology consists of a 25-cm (10-in.)-wide diamond impregnated shaving drum powered by an electric motor and contains a vacuum port for dust extraction. The concrete shaver is ideal for use on open, flat, floor areas. The shaver may also be used on slightly curved surfaces. This shaver is self-propelled and produces a smooth, even surface with little vibration. The concrete shaver is an attractive alternative to traditional pneumatic scabbling tools, which were considered the baseline in this demonstration. The use of this tool reduces worker fatigue (compared to the baseline) due to lower vibration. The shaver is more than five times faster than the five-piston pneumatic scabbler at removing contamination from concrete. Because of this increased productivity, the shaver is 50% less costly to operate than baseline technologies. The DOE has successfully demonstrated the concrete shaver for decontaminating floors for free-release surveys prior to demolition work.

  15. In-field in-design metrology target integration for advanced CD and overlay process control via DoseMapper and high order overlay correction for 28nm and beyond logic node

    NASA Astrophysics Data System (ADS)

    Ducoté, J.; Bernard-Granger, F.; Le-Gratiet, B.; Bouyssou, R.; Bianchini, R.; Marin, J. C.; Baron, M. P.; Gardet, F.; Devoivre, T.; Batail, E.; Pouly, C.; Gueze, D.; Thevenon, L.

    2013-04-01

    Current process tool performances are getting significantly enhanced by the adoption of advanced process correction application such as DoseMapper for CD or high order overlay correction for overlay. These process control capabilities need appropriate sampling to be efficient. Usually for in field metrology sampling we used to operate with metrology targets placed inside the scribe lines, however in this case the larger the chip the less scribe lines we have and the less relevant is the intrafield sampling. As ST is an IDM we have the opportunity to share with our design division this process control problematic. Since 45/40nm node we have started to put in place the so-called EMET (Embedded Metrology Target) strategy which consists in in-design metrology targets placement. Initially these targets were placed using tiling tools but it soon appeared to be not efficient and even impossible when we talk about targets involving complex metal stack. This papers talks about our current embedded metrology target strategy which has been adapted to enable appropriate target placement for CD and overlay for all critical layers from active to via/metal's. Solutions needed to be put in place to (i) keep the circuit safe by using Design Rule clean metrology targets, (ii) be highly visible by the designers by placing targets at chip floor planning definition (iii) be upgradable by enabling target re-designs without impact on chip design version.

  16. Evaluation of Iron Aluminide Weld Overlays for Erosion-Corrosion Resistant Boiler Tube Coatings in Low NOx Boilers

    SciTech Connect

    Regina, J.R.

    2000-05-16

    Iron aluminide weld overlays containing ternary additions and thermal spray coatings are being investigated for corrosion protection of boiler tubes in Low NOx burners. The primary objective of the research is to identify overlay and thermal spray compositions that provide corrosion protection of waterwall boiler tubes. In the current phase of work, preliminary corrosion tests were conducted on a binary Fe-Al alloy in multiple complex gases to determine which gases will be used for testing of the ternary alloys. Preliminary solid-state corrosion tests were also conducted to simulate slag-metal interactions seen in Low NOx furnaces. Two powder compositions were chosen for testing of the ternary alloys. A matrix of alloys to be tested in both gaseous and solid-state corrosion experiments was produced based on corrosion literature.

  17. Enumeration of phenanthrene-degrading bacteria by an overlayer technique and its use in evaluation of petroleum-contaminated sites

    SciTech Connect

    Bogardt, A.H.; Hemmingsen, B.B. )

    1992-08-01

    Bacteria that are capable of degrading polycyclic aromatic hydrocarbons were enumerated by incorporating soil and water dilutions together with fine particles of phenanthrene, a polycyclic aromatic hydrocarbon, into an agarose overlayer and pouring the mixture over a mineral salts underlayer. The phenanthrene-degrading bacteria embedded in the overlayer were recognized by a halo of clearing in the opaque phenanthrene layer. Diesel fuel- or creosote-contaminated soil and water that were undergoing bioremediation contained 6 [times] 10[sup 6] to 100 [times] 10[sup 6] phenanthrene-degrading bacteria per g and ca. 5 [times] 10[sup 5] phenanthrene-degrading bacteria per ml, respectively, whereas samples from untreated polluted sites contained substantially lower numbers. Unpolluted soil and water contained no detectable phenanthrene degraders or only very modest numbers of these organisms.

  18. Optimal overlayer inspired by Photuris firefly improves light-extraction efficiency of existing light-emitting diodes.

    PubMed

    Bay, Annick; André, Nicolas; Sarrazin, Michaël; Belarouci, Ali; Aimez, Vincent; Francis, Laurent A; Vigneron, Jean Pol

    2013-01-14

    In this paper the design, fabrication and characterization of a bioinspired overlayer deposited on a GaN LED is described. The purpose of this overlayer is to improve light extraction into air from the diode's high refractive-index active material. The layer design is inspired by the microstructure found in the firefly Photuris sp. The actual dimensions and material composition have been optimized to take into account the high refractive index of the GaN diode stack. This two-dimensional pattern contrasts other designs by its unusual profile, its larger dimensions and the fact that it can be tailored to an existing diode design rather than requiring a complete redesign of the diode geometry. The gain of light extraction reaches values up to 55% with respect to the reference unprocessed LED.

  19. Assessment of silicon carbide x-ray mask overlay performance in the IBM Advanced Lithography Facility x-ray stepper

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.; Chen, Alek C.; Powers, Lynn A.; Vampatella, Ben R.

    1995-05-01

    This paper presents the results of a study to explicitly assess the performance of silicon carbide masks by directly measuring overlay accuracy and precision of exposures made on a state-of-the-art commercially available x-ray stepper, the Suss XRS200/3. The work was done using a mask fabricated at IBM from silicon carbide coated wafers obtained from HOYA Electronics Corp. with exposures completed at IBM's Advanced Lithography Facility (ALF) using synchrotron-generated radiation. The mask pattern design contains many overlay measurement fiducials, resolution patterns, and alignment verniers, and two sets of three alignment marks: one set inboard (kerf) and one set outboard. The performance of an imaging-based alignment system, such as the ALX system on the Suss XRS200/3 steppers, varies depending upon the optical characteristics of the alignment marks on the mask and wafer.

  20. Microstructures and oxidation behavior of sputter-deposited overlay coatings based on beta-nickel aluminide

    NASA Astrophysics Data System (ADS)

    Alfano, Joel

    2011-12-01

    Nickel-based superalloy components in the hot sections of commercial gas turbine engines are often protected by aluminide coatings due to their ability to function in oxidative and corrosive environments. However, the microstructures of these coated systems are metastable and change in service due to interactions with the environment and interdiffusion with the underlying substrate. The extent of these changes depends critically upon coating microstructure, chemistry, and the environment that the coated component operates in. This thesis highlights the influences of chemical composition, post-deposition annealing, and isothermal oxidation at 1050°C on the microstructures and properties of NiAl-Zr and NiAl-Cr-Zr overlay bond coatings. In particular, the results indicated that in slightly Ni-rich NiAl-based coatings, coating/substrate interdiffusion and Al-depletion within the coating could be inhibited by increasing the Zr content from 0.3 at.% to 1.0 at.% Zr. However, subsequent additions of 5 at.% Cr to coatings containing 1 at.% Zr, resulted in interdiffusion and Al-depletion levels more similar to low Zr or Zr-free coatings. Results are discussed relative to conventional coating systems.

  1. SiMPSON: Efficient Similarity Search in Metric Spaces over P2P Structured Overlay Networks

    NASA Astrophysics Data System (ADS)

    Vu, Quang Hieu; Lupu, Mihai; Wu, Sai

    Similarity search in metric spaces over centralized systems has been significantly studied in the database research community. However, not so much work has been done in the context of P2P networks. This paper introduces SiMPSON: a P2P system supporting similarity search in metric spaces. The aim is to answer queries faster and using less resources than existing systems. For this, each peer first clusters its own data using any off-the-shelf clustering algorithms. Then, the resulting clusters are mapped to one-dimensional values. Finally, these one-dimensional values are indexed into a structured P2P overlay. Our method slightly increases the indexing overhead, but allows us to greatly reduce the number of peers and messages involved in query processing: we trade a small amount of overhead in the data publishing process for a substantial reduction of costs in the querying phase. Based on this architecture, we propose algorithms for processing range and kNN queries. Extensive experimental results validate the claims of efficiency and effectiveness of SiMPSON.

  2. A portable near-infrared fluorescence image overlay device for surgical navigation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    McWade, Melanie A.

    2016-03-01

    A rise in the use of near-infrared (NIR) fluorescent dyes or intrinsic fluorescent markers for surgical guidance and tissue diagnosis has triggered the development of NIR fluorescence imaging systems. Because NIR wavelengths are invisible to the naked eye, instrumentation must allow surgeons to visualize areas of high fluorescence. Current NIR fluorescence imaging systems have limited ease-of-use because they display fluorescent information on remote display monitors that require surgeons to divert attention away from the patient to identify the location of tissue fluorescence. Furthermore, some systems lack simultaneous visible light imaging which provides valuable spatial context to fluorescence images. We have developed a novel, portable NIR fluorescence imaging approach for intraoperative surgical guidance that provides information for surgical navigation within the clinician's line of sight. The system utilizes a NIR CMOS detector to collect excited NIR fluorescence from the surgical field. Tissues with NIR fluorescence are overlaid with visible light to provide information on tissue margins directly on the surgical field. In vitro studies have shown this versatile imaging system can be applied to applications with both extrinsic NIR contrast agents such as indocyanine green and weaker sources of biological fluorescence such as parathyroid gland tissue. This non-invasive, portable NIR fluorescence imaging system overlays an image directly on tissue, potentially allowing surgical decisions to be made quicker and with greater ease-of-use than current NIR fluorescence imaging systems.

  3. Ultra-Deep Bone Diagnostics with Fat-Skin Overlayers Using New Pulsed Photothermal Radar

    NASA Astrophysics Data System (ADS)

    Sreekumar, K.; Mandelis, A.

    2013-09-01

    The constraints imposed by the laser safety (maximum permissible exposure) ceiling on pump laser energy and the strong attenuation of thermal-wave signals in tissues significantly limit the photothermally active depth in most biological specimens to a level which is normally insufficient for practical applications (a few mm below the skin surface). A theoretical approach for improvement of the signal-to-noise ratio (SNR), minimizing the static (dc) component of the photothermal (PT) signal and making use of the PT radiometric nonlinearity has been introduced. At low frequencies fixed-pulse-width chirps of large peak power were found to be superior to all other equal energy modalities, with an SNR improvement by up to two orders of magnitude. Compared to radar peak delay and amplitude, the long-delayed radar output amplitude is found to be more sensitive to subsurface conditions. Two-dimensional spatial plots of this parameter depicting the back-surface conditions of bones with and without fat tissue overlayers are presented. Pulsed-chirp radar thermography has been demonstrated to monitor the degree of demineralization in goat rib bone with a substantial SNR and spatial resolution that is not practicable with harmonic radars of the same energy density.

  4. Interaction of epitaxial silicene with overlayers formed by exposure to Al atoms and O2 molecules.

    PubMed

    Friedlein, R; Van Bui, H; Wiggers, F B; Yamada-Takamura, Y; Kovalgin, A Y; de Jong, M P

    2014-05-28

    As silicene is not chemically inert, the study and exploitation of its electronic properties outside of ultrahigh vacuum environments require the use of insulating capping layers. In order to understand if aluminum oxide might be a suitable encapsulation material, we used high-resolution synchrotron photoelectron spectroscopy to study the interactions of Al atoms and O2 molecules, as well as the combination of both, with epitaxial silicene on thin ZrB2(0001) films grown on Si(111). The deposition of Al atoms onto silicene, up to the coverage of about 0.4 Al per Si atoms, has little effect on the chemical state of the Si atoms. The silicene-terminated surface is also hardly affected by exposure to O2 gas, up to a dose of 4500 L. In contrast, when Al-covered silicene is exposed to the same dose, a large fraction of the Si atoms becomes oxidized. This is attributed to dissociative chemisorption of O2 molecules by Al atoms at the surface, producing reactive atomic oxygen species that cause the oxidation. It is concluded that aluminum oxide overlayers prepared in this fashion are not suitable for encapsulation since they do not prevent but actually enhance the degradation of silicene.

  5. Synchrotron radiation photoemission study of metal overlayers on hydrogenated amorphous silicon at room temperature

    SciTech Connect

    Pi, J.

    1990-09-21

    In this dissertation, metals deposited on a hydrogenated amorphous silicon (a-Si:H) film at room temperature are studied. The purpose of this work is mainly understanding the electronic properties of the interface, using high-resolution synchrotron radiation photoemission techniques as a probe. Atomic hydrogen plays an important role in passivating dangling bonds of a-Si:H films, thus reducing the gap-state distribution. In addition, singly bonded hydrogen also reduces states at the top of the valence band which are now replaced by deeper Si-H bonding states. The interface is formed by evaporating metal on an a-Si:H film in successive accumulations at room temperature. Au, Ag, and Cr were chosen as the deposited metals. Undoped films were used as substrates. Since some unique features can be found in a-Si:H, such as surface enrichment of hydrogen diffused from the bulk and instability of the free surface, we do not expect the metals/a-Si:H interface to behave exactly as its crystalline counterpart. Metal deposits, at low coverages, are found to gather preferentially around regions deficient in hydrogen. As the thickness is increased, some Si atoms in those regions are likely to leave their sites to intermix with metal overlayers like Au and Cr. 129 refs., 30 figs.

  6. SLEA: A Novel Scheme for Routing in Overlay IP/WDM Networks

    NASA Astrophysics Data System (ADS)

    Ye, Tong; Su, Yikai; Zhu, Keyao; Leng, Lufeng; Zeng, Qingji; Jin, Yaohui

    2005-10-01

    This paper studies the routing problems in Internet protocol/wavelength-division-multiplexing (IP/WDM) networks based on the overlay routing algorithm (ORA) and the integrated routing algorithm (IRA), respectively. Although IRA usually outperforms ORA in terms of blocking performance, IRA exhibits disadvantages in control information exchange, network privacy issue, and wavelength port efficiency. In this paper, a new mechanism called the short lightpath establishment approach (SLEA) is proposed for ORA in order to tackle the problems in IRA and achieve similar (or even better) network performance at the same time. The main idea of SLEA is to ensure that each new lightpath created by ORA is restricted by an optical hop constraint when a subwavelength-granularity connection is routed in the optical layer. It follows that SLEA essentially avoids per-connection-based greedy treatment and improves network wide resource utilization by eliminating inefficient long optical bypasses. To implement SLEA in ORA, the Dijsktra's algorithm has been modified based on an extended layered graph model. SLEA does not introduce any additional signaling and computational complexity. The analysis and simulation in this paper show that there exists an optimal optical hop constraint for each particular network configuration such that SLEA-based ORA (SLEA-ORA) can efficiently utilize the network resource of concern. As a result, with the optimal optical hop constraint, SLEA-ORA could outperform ORA and IRA in terms of the bandwidth-blocking ratio (BBR) and the average number of IP hops of label-switched paths (LSPs).

  7. Determining the Co-Rotation Radius of Nearby Spiral Galaxies Using Spiral Arm Overlays

    NASA Astrophysics Data System (ADS)

    Shameer Abdeen, Mohamed; Kennefick, Daniel; Kennefick, Julia D.; Pour Imani, Hamed; Shields, Douglas W.; Eufrasio, Rafael; Berlanga Medina, Jazmin; Monson, Erik

    2017-01-01

    Density wave theory, originally proposed by C.C. Lin and Frank Shu (Lin & Shu 1964), views the spiral arm structures in spiral galaxies as density waves that propagates through the galactic disk. Resonances within orbits create standing wave patterns of density waves that we observe as spiral arms. The theory predicts the existence of a radius known as the co-rotation radius in which the spiral arm pattern speed matches the velocities of the stars within the disk. We introduce a novel way of determining the co-rotation radius, based on an image overlaying technique, which involves tracing the arms of spiral galaxies on images observed from different wavelengths. For the purpose of this study, 12 nearby galaxies were analyzed from four different wavelengths using pitch angle measurements from a previous study (Hamed et al. 2016). We used optical wavelength images (B-Band,440 nm), two infrared wavelength (Infrared; 3.6 µm and 8 µm) Spitzer Space Telescope images and ultraviolet images from GALEX. The results were verified by checking against results compiled from the literature.

  8. nDSE-based overlay alignment: enabling technology for nano metrology and fabrication

    NASA Astrophysics Data System (ADS)

    Gao, Jun; Picciotto, Carl; Wu, Wei; Park, Inkyu; Tong, William M.

    2006-03-01

    Displacement sensing and estimation (DSE) is important preprocessing task for many image-based processing systems that extract information from multiple images. In last two years, we gained significant insight of the nature of DSE and developed theory and algorithm framework named nanoscale displacement sensing and estimation (nDSE). We also build procedures to apply nDSE to overlay alignment down to the nanoscale. We will introduce two basic theories: Phase Delay Detection (PDD) and Derivatives-based Maximum Likelihood Estimation (DML) and associated DSE algorithms, noticeably Near-Neighbor-Navigation (N-Cubed) algorithm. We presented our best nDSE experimental result of 1 nm (1σ) while tracking 5 nm stepping. To develop nDSE-based nanoscale alignment, we introduced our definition of displacement, alignment and pseudo-displacement. We presented both theoretical and practical procedures to use nDSE to achieve nano-alignment down to the 10s of nano-meters and beyond. Then we compared nDSE-based nano-alignment to other industry standard alignment method and attempt to show the substantial advantages of nDSE based alignment in terms of cost and simplicity of the system design.

  9. Fracture properties of a neutron-irradiated stainless steel submerged arc weld cladding overlay

    SciTech Connect

    Corwin, W.R.; Berggren, R.G.; Nanstad, R.K.

    1984-01-01

    The ability of stainless steel cladding to increase the resistance of an operating nuclear reactor pressure vessel to extension of surface flaws depends greatly on the properties of the irradiated cladding. Therefore, weld overlay cladding irradiated at temperatures and fluences relevant to power reactor operation was examined. The cladding was applied to a pressure vessel steel plate by the submerged arc, single-wire, oscillating-electrode method. Three layers of cladding provided a thickness adequate for fabrication of test specimens. The first layer was type 309, and the upper two layers were type 308 stainless steel. The type 309 was diluted considerably by excessive melting of the base plate. Specimens were taken from near the base plate-cladding interface and also from the upper layers. Charpy V-notch and tensile specimens were irradiated at 288/sup 0/C to a fluence of 2 x 10/sup 23/ neutrons/m/sup 2/ (>1 MeV). 10 refs., 16 figs., 4 tabs.

  10. Software for MR image overlay guided needle insertions: the clinical translation process

    NASA Astrophysics Data System (ADS)

    Ungi, Tamas; U-Thainual, Paweena; Fritz, Jan; Iordachita, Iulian I.; Flammang, Aaron J.; Carrino, John A.; Fichtinger, Gabor

    2013-03-01

    PURPOSE: Needle guidance software using augmented reality image overlay was translated from the experimental phase to support preclinical and clinical studies. Major functional and structural changes were needed to meet clinical requirements. We present the process applied to fulfill these requirements, and selected features that may be applied in the translational phase of other image-guided surgical navigation systems. METHODS: We used an agile software development process for rapid adaptation to unforeseen clinical requests. The process is based on iterations of operating room test sessions, feedback discussions, and software development sprints. The open-source application framework of 3D Slicer and the NA-MIC kit provided sufficient flexibility and stable software foundations for this work. RESULTS: All requirements were addressed in a process with 19 operating room test iterations. Most features developed in this phase were related to workflow simplification and operator feedback. CONCLUSION: Efficient and affordable modifications were facilitated by an open source application framework and frequent clinical feedback sessions. Results of cadaver experiments show that software requirements were successfully solved after a limited number of operating room tests.

  11. Fluorescence-Based Bacterial Overlay Method for Simultaneous In Situ Quantification of Surface-Attached Bacteria▿

    PubMed Central

    Müller, Rainer; Gröger, Gerhard; Hiller, Karl-Anton; Schmalz, Gottfried; Ruhl, Stefan

    2007-01-01

    For quantification of bacterial adherence to biomaterial surfaces or to other surfaces prone to biofouling, there is a need for methods that allow a comparative analysis of small material specimens. A new method for quantification of surface-attached biotinylated bacteria was established by in situ detection with fluorescence-labeled avidin-D. This method was evaluated utilizing a silicon wafer model system to monitor the influences of surface wettability and roughness on bacterial adhesion. Furthermore, the effects of protein preadsorption from serum, saliva, human serum albumin, and fibronectin were investigated. Streptococcus gordonii, Streptococcus mitis, and Staphylococcus aureus were chosen as model organisms because of their differing adhesion properties and their clinical relevance. To verify the results obtained by this new technique, scanning electron microscopy and agar replica plating were employed. Oxidized and poly(ethylene glycol)-modified silicon wafers were found to be more resistant to bacterial adhesion than wafers coated with hydrocarbon and fluorocarbon moieties. Roughening of the chemically modified surfaces resulted in an overall increase in bacterial attachment. Preadsorption of proteins affected bacterial adherence but did not fully abolish the influence of the original surface chemistry. However, in certain instances, mostly with saliva or serum, masking of the underlying surface chemistry became evident. The new bacterial overlay method allowed a reliable quantification of surface-attached bacteria and could hence be employed for measuring bacterial adherence on material specimens in a variety of applications. PMID:17308176

  12. An investigation on microstructure and mechanical property of thermally aged stainless steel weld overlay cladding

    NASA Astrophysics Data System (ADS)

    Cao, X. Y.; Zhu, P.; Ding, X. F.; Lu, Y. H.; Shoji, T.

    2017-04-01

    Microstructural evolution and mechanical property change of E308L stainless steel weld overlay cladding aged at 400 °C for 400, 1000 and 5000 h were investigated by transmission electron microscope (TEM) and small punch test (SPT). The results indicated that thermal aging had no obvious effect on the volume fraction of ferrite, but can cause microstructural evolution by spinodal decomposotion and G-phase precipitation in the ferrite phase. Spinodal decomposition took place after aging up to 1000 h, while G-phase formed along dislocations, and growed up to 2-11 nm after aging for 5000 h. The total energy for inducing deformation and fracture by the small punch tests decreased with the increase of thermal aging time, and this decline was associated with spinodal decomposition and G-phase precipitation. Plastic deformation of the aged ferrite proceeded via formation of curvilinear slip bands. Nucleation of microcracks occurred at the δ/γ interface along the slip bands. The hardening of the ferrite and high stress concentration on δ/γ phase interface resulted in brittle fracture and phase boundary separation after thermal aging.

  13. Structured P2P Overlay of Mobile Brokers for Realizing Publish/Subscribe Communication in VANET

    PubMed Central

    Pandey, Tulika; Garg, Deepak; Gore, Manoj Madhava

    2014-01-01

    Publish/subscribe communication paradigm provides asynchrony and decoupling, making it an elegant alternative for designing applications in distributed and dynamic environment such as vehicular ad hoc networks (VANETs). In this paradigm, the broker is the most important component that decouples other two components, namely, publisher and subscriber. Previous research efforts have either utilized the deployment of distributed brokers on stationary road side info-stations or have assigned the role of broker to any moving vehicle on ad hoc basis. In one approach, lots of preinstalled infrastructures are needed whereas, in another, the quality of service is not guaranteed due to unpredictable moving and stopping patterns of vehicles. In this paper, we present the architecture of distributed mobile brokers which are dynamically reconfigurable in the form of structured P2P overlay and act as rendezvous points for matching publications and subscriptions. We have taken city buses in urban settings to act as mobile brokers whereas other vehicles are considered to be in role of publishers and subscribers. These mobile brokers also assist in locating a vehicle for successful and timely transfer of notifications. We have performed an extensive simulation study to compare our approach with previously proposed approaches. Simulation results establish the applicability of our approach. PMID:24523629

  14. Structured P2P overlay of mobile brokers for realizing publish/subscribe communication in VANET.

    PubMed

    Pandey, Tulika; Garg, Deepak; Gore, Manoj Madhava

    2014-01-01

    Publish/subscribe communication paradigm provides asynchrony and decoupling, making it an elegant alternative for designing applications in distributed and dynamic environment such as vehicular ad hoc networks (VANETs). In this paradigm, the broker is the most important component that decouples other two components, namely, publisher and subscriber. Previous research efforts have either utilized the deployment of distributed brokers on stationary road side info-stations or have assigned the role of broker to any moving vehicle on ad hoc basis. In one approach, lots of preinstalled infrastructures are needed whereas, in another, the quality of service is not guaranteed due to unpredictable moving and stopping patterns of vehicles. In this paper, we present the architecture of distributed mobile brokers which are dynamically reconfigurable in the form of structured P2P overlay and act as rendezvous points for matching publications and subscriptions. We have taken city buses in urban settings to act as mobile brokers whereas other vehicles are considered to be in role of publishers and subscribers. These mobile brokers also assist in locating a vehicle for successful and timely transfer of notifications. We have performed an extensive simulation study to compare our approach with previously proposed approaches. Simulation results establish the applicability of our approach.

  15. Overlay Results Comparison Between Two Approaches When Mixing Optical Steppers With Scanner

    NASA Astrophysics Data System (ADS)

    Dumant, J. M.; Vachet, G.; Charles, A.; Temerson, J. M.

    1989-01-01

    For the industrial production of one micron CMOS design rule circuits, it may be advantageous in terms of cost and throughput to mix projection scanners with optical steppers. Three compatibilities have then to be completed: - prealignment, interfield, intrafield. One classical way of ensuring the prealignment compatibility is to print two global marks with the stepper. To achieve the grid compatibility, the normal method is to use die by die alignment. The intrafield capability is then achieved in adjusting the magnification and distortion of the stepper to the scanner caracteristics. Nevertheless, a specific difficulty occurs when it is wished to print the first level with the stepper. In that case, two different aproaches can be considered: - First print an extra level with the scanning projection machine to create alignment marks, and afterwards print the real first level with the stepper in die by die alignment mode. - Use blind stepping under the stage interferometric metrology control to print directly the first level. Both method have been tested and characterized. Advantages and difficulties as well as overlay results are presented. A detailled analysis and quantitative evaluation of the various error causes involved were carried out. This allows the analysis to be generalized to other machines with different specifications

  16. Photon-enhanced thermionic emission from p-GaAs with nonequilibrium Cs overlayers

    SciTech Connect

    Zhuravlev, A. G.; Romanov, A. S.; Alperovich, V. L.

    2014-12-22

    Photon-enhanced thermionic emission (PETE), which is promising for increasing the efficiency of solar energy conversion, is studied during cesium deposition on the As- and Ga-rich p-GaAs(001) surfaces and subsequent relaxation in the nonequilibrium Cs overlayer by means of photoemission quantum yield spectroscopy adapted for systems with time-variable parameters. Along with direct photoemission of “hot” electrons excited by light above the vacuum level, the spectra contain PETE contribution of “thermalized” electrons, which are excited below the vacuum level and emit in vacuum due to thermalization up in energy by phonon absorption. Comparing the measured and calculated spectra, the effective electron affinity and escape probabilities of hot and thermalized electrons are obtained as functions of submonolayer Cs coverage. The minima in the affinity and pronounced peaks in the escape probabilities are observed for Cs deposition on both the As- and Ga-rich surfaces. Possible reasons for the low mean values of the electron escape probabilities and for the observed enhancement of the probabilities at certain Cs coverages are discussed, along with the implications for the PETE device realization.

  17. Overlay of neuromagnetic current-density images and morphological MR images

    NASA Astrophysics Data System (ADS)

    Fuchs, Manfred; Wischmann, Hans-Aloys; Doessel, Olaf

    1992-09-01

    Neuromagnetic imaging is a relatively new diagnostic tool for examination of electric activities in the nervous system. It is based on the noninvasive detection of extremely weak magnetic fields around the human body with superconducting quantum interference device (SQUID) detectors. `Equivalent current dipoles' and linear estimation reconstructions of current distributions both with spherical volume conductor models are used to localize the neural activity. For practical use in medical diagnosis a combination of the abstract neuromagnetic images with magnetic resonance (MR)- or computer tomography (CT)-images is required in order to match the functional activity with anatomy and morphology. The neuromagnetic images can be overlayed onto three-dimensional morphological images with spatially arbitrarily selectable slices. The matching of both imaging modalities is discussed. Based on the detection of auditory evoked magnetic fields, neuromagnetic images are reconstructed with linear estimation theory algorithms. The MR images are used as a-priori information of the volume conductor geometry and they allow an attachment of functional and morphological properties.

  18. Evaluation of index-overlay methods for groundwater vulnerability and risk assessment in Kathmandu Valley, Nepal.

    PubMed

    Shrestha, Sangam; Kafle, Ranjana; Pandey, Vishnu Prasad

    2017-01-01

    This study aimed at evaluating three index-overlay methods of vulnerability assessment (i.e., DRASTIC, GOD, and SI) for estimating risk to pollution of shallow groundwater aquifer in the Kathmandu Valley, Nepal. The Groundwater Risk Assessment Model (GRAM) model was used to compute the risk to groundwater pollution. Results showed that DRASTIC and SI methods are comparable for vulnerability assessment as both methods delineate around 80% of the groundwater basin area under high vulnerable zone. From the perspective of risk to pollution results, DRASTIC and GOD methods are comparable. Nevertheless, all the three methods estimate that at least 60% of the groundwater basin is under moderate risk to NO3-N pollution, which goes up to 75% if DRASTIC or GOD-based vulnerabilities are considered as exposure pathways. Finally, based on strength and significance of correlation between the estimated risk and observed NO3-N concentrations, it was found that SI method is a better-suited one to assess the vulnerability and risk to groundwater pollution in the study area. Findings from this study are useful to design strategies and actions aimed to prevent nitrate pollution in groundwater of Kathmandu Valley in Nepal.

  19. Curing units' ability to cure restorative composites and dual-cured composite cements under composite overlay.

    PubMed

    Park, Sung-Ho; Kim, Su-Sun; Cho, Yong-Sik; Lee, Chang-Kyu; Noh, Byng-Duk

    2004-01-01

    This study compared the efficacy of using conventional low-power density QTH (LQTH) units, high-power density QTH (HQTH) units, argon (Ar) laser and Plasma arc curing (PAC) units for curing dual-cured resin cements and restorative resin composites under a pre-cured resin composite overlay. The microhardness of the two types of restorative resins (Z100 and Tetric Ceram) and a dual-cured resin cement (Variolink II) were measured after they were light cured for 60 seconds in a 2 mm Teflon mold. The recorded microhardness was determined to be the optimum microhard-ness (OM). Either one of the two types of restorative resins (Z100, Tetric Ceram) or the dual cured resin cement (Variolink II) were placed under a 1.5-mm thick and 8 mm diameter pre-cured Targis (Vivadent/Ivoclar AG, Schaan, Liechtenstein) overlay. The specimens that were prepared for each material were divided into four groups depending upon the curing units used (HQTH, PAC, Laser or LQTH) and were further subdi-vided into subgroups according to light curing time. The curing times used were 30, 60, 90 and 120 seconds for HQTH; 12, 24, 36 and 48 seconds for the PAC unit; 15, 30, 45 and 60 for the Laser and 60, 120 or 180 seconds for the LQTH unit. Fifteen specimens were assigned to each sub- group. The microhardness of the upper and and lower composite surfaces under the Targis overlay were measured using an Optidur Vickers hardness-measuring instrument (Göttfert Feinwerktechnik GmbH, Buchen, Germany). In each material, for each group, a three-way ANOVA with Tukey was used at the 0.05 level of significance to compare the microhardnesses of the upper and lower composite surfaces and the previously measured OM of the material. From the OM of each material, 80% OM was calculated and the time required for the microhardness of the upper and lower surface of the specimen to reach 100% and 80% of OM was determined. In Z100 and Tetric Ceram, when the composites were light cured for 120 seconds using the HQTH lamp

  20. Error analysis of overlay compensation methodologies and proposed functional tolerances for EUV photomask flatness

    NASA Astrophysics Data System (ADS)

    Ballman, Katherine; Lee, Christopher; Dunn, Thomas; Bean, Alexander

    2016-05-01

    Due to the impact on image placement and overlay errors inherent in all reflective lithography systems, EUV reticles will need to adhere to flatness specifications below 10nm for 2018 production. These single value metrics are near impossible to meet using current tooling infrastructure (current state of the art reticles report P-V flatness ~60nm). In order to focus innovation on areas which lack capability for flatness compensation or correction, this paper redefines flatness metrics as being "correctable" vs. "non-correctable" based on the surface topography's contributions to the final IP budget at wafer, as well as whether data driven corrections (write compensation or at scanner) are available for the reticle's specific shape. To better understand and define the limitations of write compensation and scanner corrections, an error budget for processes contributing to these two methods is presented. Photomask flatness measurement tools are now targeting 6σ reproducibility <1nm (previous 3σ reproducibility ~3nm) in order to drive down error contributions and provide more accurate data for correction techniques. Taking advantage of the high order measurement capabilities of improved metrology tooling, as well as computational capabilities which enable fast measurements and analysis of sophisticated shapes, we propose a methodology for the industry to create functional tolerances focused on the flatness errors that are not correctable with compensation.

  1. Optical resonance analysis of reflected long period fiber gratings with metal film overlay

    NASA Astrophysics Data System (ADS)

    Zhang, Guiju; Cao, Bing; Wang, Chinua; Zhao, Minfu

    2008-11-01

    We present the experimental results of a novel single-ended reflecting surface plasma resonance (SPR) based long period fiber grating (LPFG) sensor. A long period fiber grating sensing device is properly designed and fabricated with a pulsed CO2 laser writing system. Different nm-thick thin metal films are deposited on the fiber cladding and the fiber end facet for the excitation of surface plasma waves (SPWs) and the reflection of the transmission spectrum of the LPFG with doubled interaction between metal-dielectric interfaces of the fiber to enhance the SPW of the all-fiber SPR-LPFG sensing system. Different thin metal films with different thicknesses are investigated. The effect of the excited SPW transmission along the fiber cladding-metal interface with silver and aluminum films is observed. It is found that different thicknesses of the metal overlay show different resonant behaviors in terms of resonance peak situation, bandwidth and energy loss. Within a certain range, thinner metal film shows narrower bandwidth and deeper peak loss.

  2. Nanomechanics and Multiscale Modeling of Sustainable Concretes

    NASA Astrophysics Data System (ADS)

    Zanjani Zadeh, Vahid

    The work presented in this dissertation is aimed to implement and further develop the recent advances in material characterization for porous and heterogeneous materials and apply these advances to sustainable concretes. The studied sustainable concretes were concrete containing fly ash and slag, Kenaf fiber reinforced concrete, and lightweight aggregate concrete. All these cement-based materials can be categorized as sustainable concrete, by achieving concrete with high strength while reducing cement consumption. The nanoindentation technique was used to infer the nanomechanical properties of the active hydration phases in bulk cement paste. Moreover, the interfacial transition zone (ITZ) of lightweight aggregate, normal aggregate, and Kenaf fibers were investigated using nanoindentation and imagine techniques, despite difficulties regarding characterizing this region. Samples were also tested after exposure to high temperature to evaluate the damage mechanics of sustainable concretes. It has been shown that there is a direct correlation between the nature of the nanoscale structure of a cement-based material with its macroscopic properties. This was addressed in two steps in this dissertation: (i) Nanoscale characterization of sustainable cementitious materials to understand the different role of fly ash, slag, lightweight aggregate, and Kenaf fibers on nanoscale (ii) Link the nanoscale mechanical properties to macroscale ones with multiscale modeling. The grid indentation technique originally developed for normal concrete was extended to sustainable concretes with more complex microstructure. The relation between morphology of cement paste materials and submicron mechanical properties, indentation modulus, hardness, and dissipated energy is explained in detail. Extensive experimental and analytical approaches were focused on description of the materials' heterogeneous microstructure as function of their composition and physical phenomenon. Quantitative

  3. SUSTAINABLE CONCRETE FOR WIND TURBINE FOUNDATIONS.

    SciTech Connect

    BERNDT,M.L.

    2004-06-01

    The use of wind power to generate electricity continues to grow, especially given commitments by various countries throughout the world to ensure that a significant percentage of energy comes from renewable sources. In order to meet such objectives, increasingly larger turbines with higher capacity are being developed. The engineering aspects of larger turbine development tend to focus on design and materials for blades and towers. However, foundations are also a critical component of large wind turbines and represent a significant cost of wind energy projects. Ongoing wind research at BNL is examining two areas: (a) structural response analysis of wind turbine-tower-foundation systems and (b) materials engineering of foundations. This work is investigating the dynamic interactions in wind turbine systems, which in turn assists the wind industry in achieving improved reliability and more cost efficient foundation designs. The results reported herein cover initial studies of concrete mix designs for large wind turbine foundations and how these may be tailored to reduce cost and incorporate sustainability and life cycle concepts. The approach taken was to investigate material substitutions so that the environmental, energy and CO{sub 2}-impact of concrete could be reduced. The use of high volumes of ''waste'' materials in concrete was examined. These materials included fly ash, blast furnace slag and recycled concrete aggregate. In addition, the use of steel fiber reinforcement as a means to improve mechanical properties and potentially reduce the amount of bar reinforcement in concrete foundations was studied. Four basic mixes were considered. These were: (1) conventional mix with no material substitutions, (2) 50% replacement of cement with fly ash, (3) 50% replacement of cement with blast furnace slag and (4) 25% replacement of cement with fly ash and 25% replacement with blast furnace slag. Variations on these mixes included the addition of 1% by volume steel

  4. Wafer-based aberration metrology for lithographic systems using overlay measurements on targets imaged from phase-shift gratings.

    PubMed

    van Haver, Sven; Coene, Wim M J; D'havé, Koen; Geypen, Niels; van Adrichem, Paul; de Winter, Laurens; Janssen, Augustus J E M; Cheng, Shaunee

    2014-04-20

    In this paper, a new methodology is presented to derive the aberration state of a lithographic projection system from wafer metrology data. For this purpose, new types of phase-shift gratings (PSGs) are introduced, with special features that give rise to a simple linear relation between the PSG image displacement and the phase aberration function of the imaging system. By using the PSGs as the top grating in a diffraction-based overlay stack, their displacement can be measured as an overlay error using a standard wafer metrology tool. In this way, the overlay error can be used as a measurand based on which the phase aberration function in the exit pupil of the lithographic system can be reconstructed. In practice, the overlay error is measured for a set of different PSG targets, after which this information serves as input to a least-squares optimization problem that, upon solving, provides estimates for the Zernike coefficients describing the aberration state of the lithographic system. In addition to a detailed method description, this paper also deals with the additional complications that arise when the method is implemented experimentally and this leads to a number of model refinements and a required calibration step. Finally, the overall performance of the method is assessed through a number of experiments in which the aberration state of the lithographic system is intentionally detuned and subsequently estimated by the new method. These experiments show a remarkably good agreement, with an error smaller than 5  mλ, among the requested aberrations, the aberrations measured by the on-tool aberration sensor, and the results of the new wafer-based method.

  5. Pavement Evaluation and Overlay Design Using Vibratory Nondestructive Testing and Layered Elastic Theory. Volume II. Validation of Procedure.

    DTIC Science & Technology

    1980-05-01

    8217 a’_. " " W-’-’-- "൒. Work Unit No. (TRAIS) U. S. Army Engineer Waterways Experiment Station Geotechnical Laboratory / &.F7WI 7 P. 0. Box...PREFACE This study was conducted during the period October 1977 to December 1978 by personnel of the Geotechnical Laboratory (GL), U. S. Army Engineer ...overlay thickness required to upgrade a pavement is of much importance to pavement engineers . A simple method of pavement evaluation combining

  6. Shrinkage deformation of cement foam concrete

    NASA Astrophysics Data System (ADS)

    Kudyakov, A. I.; Steshenko, A. B.

    2015-01-01

    The article presents the results of research of dispersion-reinforced cement foam concrete with chrysotile asbestos fibers. The goal was to study the patterns of influence of chrysotile asbestos fibers on drying shrinkage deformation of cement foam concrete of natural hardening. The chrysotile asbestos fiber contains cylindrical fiber shaped particles with a diameter of 0.55 micron to 8 microns, which are composed of nanostructures of the same form with diameters up to 55 nm and length up to 22 microns. Taking into account the wall thickness, effective reinforcement can be achieved only by microtube foam materials, the so- called carbon nanotubes, the dimensions of which are of power less that the wall pore diameter. The presence of not reinforced foam concrete pores with perforated walls causes a decrease in its strength, decreases the mechanical properties of the investigated material and increases its shrinkage. The microstructure investigation results have shown that introduction of chrysotile asbestos fibers in an amount of 2 % by weight of cement provides the finely porous foam concrete structure with more uniform size closed pores, which are uniformly distributed over the volume. This reduces the shrinkage deformation of foam concrete by 50%.

  7. Compressive strength of dune sand reinforced concrete

    NASA Astrophysics Data System (ADS)

    Mohammed, Mani; Abdelouahed, Kriker; Allaoua, Belferrag

    2017-02-01

    Many areas of south Algeria suffer from the problem of accumulation of sand on constructions. In fact, the phenomenon of sand silting causes technical and economical problems. Besides, these areas and other regions in Algeria suffer from the problem of unavailability of suitable sand for building. The use of dune sand offers an alternative solution for construction. In the same context, many researches confirm the possibility of using dune sand in the composition of concrete. In this paper, concrete made with dune sand was studied. For correction of the granulometry of dune sand by river sand, the rates of 50% DS+50% RS and 40% DS+60% RS were used. Also, two types of fibers were used, with 45 and 30 mm lengths, and diameters of 1 and 0.5 mm respectively. The percentage of the used fibers in the sand concrete was 1% and 1.5%. In this work an improvement of the compressive strength for the metal fibers reinforced sand concrete compared to plain concrete was obtained.

  8. Micromechanical Modeling of Concrete at Early Age

    NASA Astrophysics Data System (ADS)

    Tuleubekov, Kairat

    The focus of this research is a micromechanical characterization of Portland cement concrete at early age (less than 28 days). Concrete's viscoelastic properties change significantly at early age due to solidification of its matrix component. Bazant's solidification theory models concrete as a material solidifying in time. This approach is generalized to a three-dimensional characterization of a composite material with a solidifying matrix and elastic inclusions. An integral constitutive relationship was obtained using a generalized correspondence principle and homogenization techniques for elastic composite materials. In light of this approach, effective creep properties of composite spherical assemblage with an aging matrix are obtained. In addition, the elastic Hashin-Monteiro model is generalized to account for the effect of the interfacial transition zone properties on concrete creep. An effective computational platform was developed to evaluate operator expressions in order to obtain relaxation and creep functions numerically. Through numerical examples, it is shown that triaxial generalization of Bazant's solidification model enables robust and computationally efficient prediction of creep deformations in Portland cement concrete.

  9. Boric Acid Corrosion of Concrete Rebar

    NASA Astrophysics Data System (ADS)

    Pabalan, R. T.; Yang, L.; Chiang, K.–T.

    2013-07-01

    Borated water leakage through spent fuel pools (SFPs) at pressurized water reactors is a concern because it could cause corrosion of reinforcement steel in the concrete structure and compromise the integrity of the structure. Because corrosion rate of carbon steel in concrete in the presence of boric acid is lacking in published literature and available data are equivocal on the effect of boric acid on rebar corrosion, corrosion rate measurements were conducted in this study using several test methods. Rebar corrosion rates were measured in (i) borated water flowing in a simulated concrete crack, (ii) borated water flowing over a concrete surface, (iii) borated water that has reacted with concrete, and (iv) 2,400 ppm boric acid solutions with pH adjusted to a range of 6.0 to 7.7. The corrosion rates were measured using coupled multielectrode array sensor (CMAS) and linear polarization resistance (LPR) probes, both made using carbon steel. The results indicate that rebar corrosion rates are low (~1 μm/yr or less)when the solution pH is ~7.1 or higher. Below pH ~7.1, the corrosion rate increases with decreasing pH and can reach ~100 μm/yr in solutions with pH less than ~6.7. The threshold pH for carbon steel corrosion in borated solution is between 6.8 and 7.3.

  10. Predicting the remaining service life of concrete

    SciTech Connect

    Clifton, J.F.

    1991-11-01

    Nuclear power plants are providing, currently, about 17 percent of the U.S. electricity and many of these plants are approaching their licensed life of 40 years. The U.S. Nuclear Regulatory Commission and the Department of Energy`s Oak Ridge National Laboratory are carrying out a program to develop a methodology for assessing the remaining safe-life of the concrete components and structures in nuclear power plants. This program has the overall objective of identifying potential structural safety issues, as well as acceptance criteria, for use in evaluations of nuclear power plants for continued service. The National Institute of Standards and Technology (NIST) is contributing to this program by identifying and analyzing methods for predicting the remaining life of in-service concrete materials. This report examines the basis for predicting the remaining service lives of concrete materials of nuclear power facilities. Methods for predicting the service life of new and in-service concrete materials are analyzed. These methods include (1) estimates based on experience, (2) comparison of performance, (3) accelerated testing, (4) stochastic methods, and (5) mathematical modeling. New approaches for predicting the remaining service lives of concrete materials are proposed and recommendations for their further development given. Degradation processes are discussed based on considerations of their mechanisms, likelihood of occurrence, manifestations, and detection. They include corrosion, sulfate attack, alkali-aggregate reactions, frost attack, leaching, radiation, salt crystallization, and microbiological attack.

  11. The Effects of Carbide Characteristics on the Performance of Tungsten Carbide-Based Composite Overlays, Deposited by Plasma-Transferred Arc Welding

    NASA Astrophysics Data System (ADS)

    Fisher, G.; Wolfe, T.; Meszaros, K.

    2013-06-01

    In Alberta, there are huge quantities of ore processed to remove bitumen from oil sands deposits. The scale of production generates very aggressive tribocorrosive conditions during the mining, extraction, and upgrading processes. It is common to apply tungsten carbide-based composite overlays to improve the reliability and extend service lives of equipment and components. The performance of the applied overlays is largely dependent on the selection of the carbide type and the wear environment. This paper will evaluate overlays containing macrocrystalline, angular eutectic, and spherical eutectic tungsten carbides and discuss the performance of the overlays with a focus on carbide properties and the interactions between the service conditions and the composite material. This discussion will demonstrate how effective selection of protective materials can improve the reliability of oil sands equipment.

  12. Assessment of Weld Overlays for Mitigating Primary Water Stress Corrosion Cracking at Nickel Alloy Butt Welds in Piping Systems Approved for Leak-Before-Break

    SciTech Connect

    Sullivan, Edward J.; Anderson, Michael T.

    2012-08-01

    This TLR provides an assessment of weld overlays as a mitigation strategy for PWSCC, and includes an assessment of the WOL-related inspection requirements of Code Case N-770-1, as conditioned in §50.55a.

  13. Highly Efficient Copper-Indium-Selenide Quantum Dot Solar Cells: Suppression of Carrier Recombination by Controlled ZnS Overlayers.

    PubMed

    Kim, Jae-Yup; Yang, Jiwoong; Yu, Jung Ho; Baek, Woonhyuk; Lee, Chul-Ho; Son, Hae Jung; Hyeon, Taeghwan; Ko, Min Jae

    2015-11-24

    Copper-indium-selenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due to their low toxicity, narrow band gap, and high absorption coefficient. Here, we demonstrate that the photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing the thickness of ZnS overlayers on the QD-sensitized TiO2 electrodes. By roughly doubling the thickness of the overlayers compared to the conventional one, conversion efficiency is enhanced by about 40%. Impedance studies reveal that the thick ZnS overlayers do not affect the energetic characteristics of the photoanode, yet enhance the kinetic characteristics, leading to more efficient photovoltaic performance. In particular, both interfacial electron recombination with the electrolyte and nonradiative recombination associated with QDs are significantly reduced. As a result, our best cell yields a conversion efficiency of 8.10% under standard solar illumination, a record high for heavy metal-free QD solar cells to date.

  14. Aspects of the application of positron emission tomography to engineering studies: Drawing overlays and correction for photon attenuation

    NASA Astrophysics Data System (ADS)

    O'Dwyer, M. A.; Hawkesworth, M. R.; Walker, J.

    1988-12-01

    Two important aspects of the application of positron emission tomography in engineering are: the creation of accurate but simplified engineering drawings to overlay the radiolabel tomograms as an aid to their interpretation, and the correction of important features in tomograms for attenuation in overlying metal to provide quantitative information. The practical difficulties met in producing overlays and correcting for attenuation are described, and strategies which are proving useful to overcome them are outlined. The essential starting point is the creation in computer memory of a full three-dimensional representation of all the subject of interest. After scaling, any plane through this model can then be extracted to overlay the appropriate plane through the radiolabel distribution, and all acceptable photon trajectories can be traced from each volume element containing positron emitter to give correction factors for attenuation in the materials traversed. It is shown that it is appropriate to use the total attenuation coefficients of materials in the correction and, finally, a gradient-contour routine is described for separating true signal from background prior to correction.

  15. Enhanced interfacial adhesion and osteogenesis for rapid "bone-like" biomineralization by PECVD-based silicon oxynitride overlays.

    PubMed

    Ilyas, Azhar; Lavrik, Nickolay V; Kim, Harry K W; Aswath, Pranesh B; Varanasi, Venu G

    2015-07-22

    Structurally unstable fracture sites require metal fixative devices, which have long healing times due to their lack of osteoinductivity. Bioactive glass coatings lack in interfacial bonding, delaminate, and have reduced bioactivity due to the high temperatures used for their fabrication. Here, we test the hypothesis that low-temperature PECVD amorphous silica can enhance adhesion to the underlying metal surface and that N incorporation enhances osteogenesis and rapid biomineralization. A model Ti/TiO2-SiOx interface was formed by first depositing Ti onto Si wafers, followed by surface patterning, thermal annealing to form TiO2, and depositing SiOx/Si(ON)x overlays. TEM micrographs showed conformal SiOx layers on Ti/TiO2 overlays while XPS data revealed the formation of an elemental Ti-O-Si interface. Nanoscratch testing verified strong SiOx bonding with the underlying TiO2 layers. In vitro studies showed that the surface properties changed significantly to reveal the formation of hydroxycarbonate apatite within 6 h, and Si(ON)x surface chemistry induced osteogenic gene expression of human periosteal cells and led to a rapid "bone-like" biomineral formation within 4 weeks. XANES data revealed that the incorporation of N increased the surface HA bioactivity by increasing the carbonate to phosphate ratio. In conclusion, silicon oxynitride overlays on bone-implant systems enhance osteogenesis and biomineralization via surface nitrogen incorporation.

  16. 0.7-NA DUV step-and-scan system for 150-nm imaging with improved overlay

    NASA Astrophysics Data System (ADS)

    van Schoot, Jan B.; Bornebroek, Frank; Suddendorf, Manfred; Mulder, Melchior; van der Spek, Jeroen; Stoeten, Jan; Hunter, Adolph; Ruemmer, Peter

    1999-07-01

    To extend KrF lithography below the 180nm SIA design rule node in manufacturing, an advanced DUV step and scan system utilizing a lens with an NA up to 0.7 will be required to provide sufficient process latitude. Towards the SIA's 150nm design rule node, manufacturing challenges for 248nm lithography include contact hole printing, iso-dense bias control and adequate across the field CD uniformity. All will benefit from higher NA lenses. In the paper, result obtained on a PAS 5500/700B DUV Step and Scan system are presented. The system design is based on the PAS 5500/500 with a new 0.7NA Starlith lens, AERIAL II illuminator and ATHENA advanced alignment system. Imaging of dense and isolated lines at 180nm, 150nm and below as well as 180nm and 160nm contact holes is shown. In addition to imaging performance, image plane deviation, system distortion fingerprints, single-machine overlay and multiple-machine matching results are shown. Using the ATHENA alignment system, alignment reproducibility as well as overlay result on CMP wafers will be shown. It is concluded that this exposure tool is capable of delivering imaging and overlay performance required for mass production at the 150nm design rule node, with potential for R and D applications beyond.

  17. First-principles study of nitric oxide oxidation on Pt(111) versus Pt overlayer on 3d transition metals

    SciTech Connect

    Arevalo, Ryan Lacdao; Escaño, Mary Clare Sison; Kasai, Hideaki

    2015-03-15

    Catalytic oxidation of NO to NO{sub 2} is a significant research interest for improving the quality of air through exhaust gas purification systems. In this paper, the authors studied this reaction on pure Pt and Pt overlayer on 3d transition metals using kinetic Monte Carlo simulations coupled with density functional theory based first principles calculations. The authors found that on the Pt(111) surface, NO oxidation proceeds via the Eley–Rideal mechanism, with O{sub 2} dissociative adsorption as the rate-determining step. The oxidation path via the Langmuir–Hinshelwood mechanism is very slow and does not significantly contribute to the overall reaction. However, in the Pt overlayer systems, the oxidation of NO on the surface is more thermodynamically and kinetically favorable compared to pure Pt. These findings are attributed to the weaker binding of O and NO on the Pt overlayer systems and the binding configuration of NO{sub 2} that promotes easier N-O bond formation. These results present insights for designing affordable and efficient catalysts for NO oxidation.

  18. The migration law of overlay rock and coal in deeply inclined coal seam with fully mechanized top coal caving.

    PubMed

    Liu, Jian; Chen, Shan-Le; Wang, Hua-Jun; Li, Yu-Cheng; Geng, Xiaowei

    2015-07-01

    In a mine area, some environment geotechnics problems always occure, induced by mined-out region such as the subsidence and cracks at ground level, deformation and destruction of buildings, landslides destruction of water resources and the ecological environment. In order to research the migration of surrounding rock and coal in steeply inclined super high seams which used fully mechanized top coal caving, a working face of a certain mine was made as an example, analyzed the migration law of the overlay rock and coal under different caving ratio of fully mechanized top coal caving with numerical simulation analysis. The results suggest that the laws of overlay rock deformation caused by deeply inclined coal seam were different from horizontal coal seam. On the inclined direction, with an increase of dip angle and caving ratio, the vertical displacement of overlay rock and coal became greater, the asymmetric phenomenon of vertical displacement became obvious. On the trend direction, active region and transition region in goaf became smaller along with the increase of mining and caving ratio. On the contrary, the stable region area became greater. Therefore, there was an essential difference between the mechanism of surface movement deformation with deeply inclined coal seam and that with horizontal coal seam.

  19. Modeling of Multi-Layered Protection Systems for Chloride Penetration in Concrete Bridge Decks

    NASA Astrophysics Data System (ADS)

    Harajli, Ali A.

    Modeling of Multi-Layered Protection Systems for Chloride Penetration in Concrete Bridge Decks. This paper covers the development of a new methodology for predicting the chloride concentration and corrosion initiation times for a multi-layer protection overlay system. The first topic will be presenting an innovative method to predict the chloride concentrations using different diffusion coefficients for each protective layer. The new method covers the cases where the applied surface chloride concentrations are either a constant or linear functions with time. The second topic will implement the results from field data about the chloride variations due to the presence of applied topical layers for comparison with the theoretical models. This section will also apply damage factors that are time-dependent to simulate external factors such as traffic loading or vibrations. The third topic will investigate the sensitivity of the single and multi-layer systems due to diffusivity parameter changes. The fourth topic will analyze the random variation of the diffusivity values to predict the mean and standard deviation of chloride concentrations. The diffusivity values are selected from published values by NIST and are based on certain water cement (w/c) ratios.

  20. Development of polymer concrete for dike insulation at LNG facilities: Phase 4, Low cost materials

    SciTech Connect

    Kukacka, L.E.

    1991-01-01

    Earlier GRI-sponsored work at Brookhaven National Laboratory has resulted in the development and utilization of insulating polymer concrete composites (IPC) as a means of reducing the evaporation rate of liquified natural gas in the event of a spill into a containment dike, thereby improving the safety at these sites. Although all of the required properties can be attained with the IPC, it was estimated that a low-cost replacement for the expensive organic binder would be necessary before use of the material would be cost-effective. In the current program, several latex modified cement formulations were evaluated and the most promising one identified. A mixture of two carboxylated styrene-butadiene latexes was selected for use in detailed laboratory property characterizations and a subsequent field evaluation. When compared to the properties of IPC, the latex-modified insulating materials display somewhat higher thermal conductivities, greater permeability to water, and reduced strength. However, these properties still meet most of the performance criteria, and the unit cost of the material is less than one-fifth that of IPC made with epoxy binders. When installed as a 0.75-in. thick overlay, material costs are estimated to be $1.00/ft{sup 2}.

  1. Confirmation of Slow-Waves in a Crosstie Overlay Coplanar Waveguide and Its Application to Band-Reject Gratings and Reflectors.

    DTIC Science & Technology

    1988-03-01

    structures in a printed circuit form constructed with crosstie overlay slow - wave structures . It is well known [31] that the electromagnetic wave propagating...proposed new crosstie overlay slow - wave structures are believed to be potentially useful for miniaturization of distributed circuits in GaAs MMIC’s...candidates for new slow - wave mechanism implementation 10 2.2 Slow - wave principle and waveguide structure for the

  2. Flow conditions of fresh mortar and concrete in different pipes

    SciTech Connect

    Jacobsen, Stefan; Haugan, Lars; Hammer, Tor Arne; Kalogiannidis, Evangelos

    2009-11-15

    The variation in fresh concrete flow rate over the pipe cross section was investigated on differently coloured and highly flowable concrete mixes flowing through pipes of different materials (rubber, steel, acryl). First, uncoloured (gray) concrete was poured through the pipe and the pipe blocked. Similar but coloured (black) concrete was then poured into the pipe filled with gray concrete, flowing after the gray concrete for a while before being blocked and hardened. The advance of the colouring along the pipe wall (showing boundary flow rate) was observed on the moulded concrete surface appearing after removing the pipe from the hardened concrete. The shapes of the interfaces between uncoloured and coloured concrete (showing variation of flow rate over the pipe cross section) were observed on sawn surfaces of concrete half cylinders cut along the length axes of the concrete-filled pipe. Flow profiles over the pipe cross section were clearly seen with maximum flow rates near the centre of the pipe and low flow rate at the pipe wall (typically rubber pipe with reference concrete without silica fume and/or stabilizers). More plug-shaped profiles, with long slip layers and less variation of flow rate over the cross section, were also seen (typically in smooth acrylic pipes). Flow rate, amount of concrete sticking to the wall after flow and SEM-images of pipe surface roughness were observed, illustrating the problem of testing full scale pumping.

  3. Concrete Waste Recycling Process for High Quality Aggregate

    SciTech Connect

    Ishikura, Takeshi; Fujii, Shin-ichi

    2008-01-15

    Large amount of concrete waste generates during nuclear power plant (NPP) dismantling. Non-contaminated concrete waste is assumed to be disposed in a landfill site, but that will not be the solution especially in the future, because of decreasing tendency of the site availability and natural resources. Concerning concrete recycling, demand for roadbeds and backfill tends to be less than the amount of dismantled concrete generated in a single rural site, and conventional recycled aggregate is limited of its use to non-structural concrete, because of its inferior quality to ordinary natural aggregate. Therefore, it is vital to develop high quality recycled aggregate for general uses of dismantled concrete. If recycled aggregate is available for high structural concrete, the dismantling concrete is recyclable as aggregate for industry including nuclear field. Authors developed techniques on high quality aggregate reclamation for large amount of concrete generated during NPP decommissioning. Concrete of NPP buildings has good features for recycling aggregate; large quantity of high quality aggregate from same origin, record keeping of the aggregate origin, and little impurities in dismantled concrete such as wood and plastics. The target of recycled aggregate in this development is to meet the quality criteria for NPP concrete as prescribed in JASS 5N 'Specification for Nuclear Power Facility Reinforced Concrete' and JASS 5 'Specification for Reinforced Concrete Work'. The target of recycled aggregate concrete is to be comparable performance with ordinary aggregate concrete. The high quality recycled aggregate production techniques are assumed to apply for recycling for large amount of non-contaminated concrete. These techniques can also be applied for slightly contaminated concrete dismantled from radiological control area (RCA), together with free release survey. In conclusion: a technology on dismantled concrete recycling for high quality aggregate was developed

  4. An elastoplastic damage constitutive model for concrete

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Lin, Gao; Zhong, Hong

    2013-04-01

    An elastoplastic damage constitutive model to simulate nonlinear behavior of concrete is presented. Similar to traditional plastic theory, the irreversible deformation is modeled in effective stress space. In order to better describe different stiffness degradation mechanisms of concrete under tensile and compressive loading conditions, two damage variables, i.e., tension and compression are introduced, to quantitatively evaluate the degree of deterioration of concrete structure. The rate dependent behavior is taken into account, and this model is derived firmly in the framework of irreversible thermodynamics. Fully implicit backward-Euler algorithm is suggested to perform constitutive integration. Numerical results of the model accord well with the test results for specimens under uniaxial tension and compression, biaxial loading and triaxial loading. Failure processes of double-edge-notched (DEN) specimen are also simulated to further validate the proposed model.

  5. Concrete decontamination by electro-hydraulic scabbling

    SciTech Connect

    Goldfarb, V.; Gannon, R.

    1995-10-01

    Textron Defense Systems (TDS) is developing an electro-hydraulic device that has the potential for faster, safer, and less expensive scabbling of contaminated concrete surfaces. In the device, shock waves and cavitating bubbles are produced in water by the electric pulses, and the direct and reflected shock waves impinging on the concrete surface result in the crushing and cracking of the concrete. Pulse energy, frequency, and traverse speed control the depth of the scabbling action. Performance thus far has demonstrated the capability of a prototype unit to process a swath 24 inches wide, up to 3/4 inch deep at a linear velocity of up to 6 feet per hour, i.e., at a scabbling rate of 12 sq. ft. per hour.

  6. The feasibility of recycling contaminated concrete

    SciTech Connect

    Ayers, K.W,; Corroon, W.; Parker, F.L.

    1999-07-01

    The changing mission of the Department of Energy along with the aging of many of its facilities has resulted in renewed emphasis on decontaminating and decommissioning surplus structures. Currently DOE is decontaminating some concrete and sending the clean material to C and D disposal facilities. In other instance, DOE is sending contaminated concrete to LLW disposal facilities. This paper examines the economic feasibility of decontaminating the concrete and recycling the rubble as clean aggregate. A probabilistic cost model was used to examine six potential recycling and disposal scenarios. The model predicted potential costs saving across the DOE complex of nearly one billion dollars. The ability of local markets to assimilate the recycled material was estimated for Washington, Idaho, Tennessee, New Mexico, and South Carolina. The relationships between a number of the economic model's variables were examined to develop operating ranges for initial managerial evaluation of recycling.

  7. Concrete Slump Classification using GLCM Feature Extraction

    NASA Astrophysics Data System (ADS)

    Andayani, Relly; Madenda, Syarifudin

    2016-05-01

    Digital image processing technologies have been widely applies in analyzing concrete structure because the accuracy and real time result. The aim of this study is to classify concrete slump by using image processing technique. For this purpose, concrete mix design of 30 MPa compression strength designed with slump of 0-10 mm, 10-30 mm, 30-60 mm, and 60-180 mm were analysed. Image acquired by Nikon Camera D-7000 using high resolution was set up. In the first step RGB converted to greyimage than cropped to 1024 x 1024 pixel. With open-source program, cropped images to be analysed to extract GLCM feature. The result shows for the higher slump contrast getting lower, but higher correlation, energy, and homogeneity.

  8. Nuclear Concrete Materials Database Phase I Development

    SciTech Connect

    Ren, Weiju; Naus, Dan J

    2012-05-01

    The FY 2011 accomplishments in Phase I development of the Nuclear Concrete Materials Database to support the Light Water Reactor Sustainability Program are summarized. The database has been developed using the ORNL materials database infrastructure established for the Gen IV Materials Handbook to achieve cost reduction and development efficiency. In this Phase I development, the database has been successfully designed and constructed to manage documents in the Portable Document Format generated from the Structural Materials Handbook that contains nuclear concrete materials data and related information. The completion of the Phase I database has established a solid foundation for Phase II development, in which a digital database will be designed and constructed to manage nuclear concrete materials data in various digitized formats to facilitate electronic and mathematical processing for analysis, modeling, and design applications.

  9. Nonlinear fracture of concrete and ceramics

    NASA Technical Reports Server (NTRS)

    Kobayashi, Albert S.; Du, Jia-Ji; Hawkins, Niel M.; Bradt, Richard C.

    1989-01-01

    The nonlinear fracture process zones in an impacted unnotched concrete bend specimen, a prenotched ceramic bend specimen, and an unnotched ceramic/ceramic composite bend specimen were estimated through hybrid experimental numerical analysis. Aggregate bridging in concrete, particulate bridging in ceramics, and fiber bridging in ceramic/ceramic composite are modeled by Barenblatt-type cohesive zones which are incorporated into the finite-element models of the bend specimens. Both generation and propagation analyses are used to estimate the distribution of crack closure stresses in the nonlinear fracture process zones. The finite-element models are then used to simulate fracture tests consisting of rapid crack propagation in an impacted concrete bend specimen, and stable crack growth and strain softening in a ceramic and ceramic/ceramic composite bend specimens.

  10. Innovative technology summary report: Concrete grinder

    SciTech Connect

    1998-09-01

    The Flex concrete grinder is a lightweight, hand-held concrete and coating removal system used for decontaminating or stripping concrete surfaces. The US Department of Energy has successfully demonstrated it for decontaminating walls and floors for free release surveys prior to demolition work. The grinder is an electric-powered tool with a vacuum port for dust extraction and a diamond grinding wheel. The grinder is suitable for flat or slightly curved surfaces and results in a smooth surface, which makes release surveys more reliable. The grinder is lightweight and produces very little vibration, thus reducing worker fatigue. The grinder is more efficient than traditional baseline, tools at removing contamination from concrete surfaces (more than four times faster than hand-held pneumatic scabbling and scaling tools). Grinder consumables (i.e., replacement diamond grinding wheel) are more expensive than the replacement carbide parts for the scaler and scabbler. However, operating costs are outweighed by the lower purchase price of the grinder (50% of the price of the baseline scaler and 8% of the price of the baseline scabbler). Overall, the concrete grinder is an attractive alternative to traditional scabbling and scaling pneumatic tools. To this end, in July 1998, the outer rod room exposed walls of the Safe Storage Enclosure (SSE), an area measuring approximately 150 m{sup 2}, may be decontaminated with the hand-held grinder. This concrete grinder technology was demonstrated for the first time at the DOE`s Hanford Site. Decontamination of a sample room walls was performed at the C Reactor to free release the walls prior to demolition. The demonstration was conducted by onsite D and D workers, who were instructed by the vendor prior to and during the demonstration.

  11. Estimating crack growth in temperature damaged concrete

    NASA Astrophysics Data System (ADS)

    Recalde, Juan Jose

    2009-12-01

    Evaluation of the structural condition of deteriorated concrete infrastructure and evaluation of new sustainable cementitious materials require an understanding of how the material will respond to applied loads and environmental exposures. A fundamental understanding of how microstructural changes in these materials relate to changes in mechanical properties and changes in fluid penetrability is needed. The ability to provide rapid, inexpensive assessment of material characteristics and relevant engineering properties is valuable for decision making and asset management purposes. In this investigation, the effects of changes in dynamic elastic properties with water content and fluid penetrability properties before and after a 300°C exposure were investigated based on estimates of the crack density parameter from dry and saturated cracked media. The experimental and analytical techniques described in this dissertation allow calculation of a value for the crack density parameter using nondestructive determination of wet and dry dynamic shear modulus of relatively thin disks. The techniques were used to compare a conventional concrete mixture to several mixtures with enhanced sustainability characteristics. The three enhanced sustainable materials investigated were a very high fly ash mixture, a magnesium phosphate cement based mortar, and a magnesium phosphate cement based concrete, and were compared to a conventional concrete mixture. The analysis provided both quantitative assessment of changes with high temperature damage and autogenous healing, and estimates of changes in mean crack trace lengths. The results showed that water interaction, deterioration due to damage, and autogenous healing recovery were different for the magnesium phosphate cement based mixtures than the portland cement based concrete mixtures. A strong correlation was found between log-transformed Air Permeability Index, dynamic shear modulus, and crack density parameter. The findings imply

  12. TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW

    SciTech Connect

    Langton, C.

    2012-05-11

    Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

  13. Concrete material characterization reinforced concrete tank structure Multi-Function Waste Tank Facility

    NASA Astrophysics Data System (ADS)

    Winkel, B. V.

    1995-03-01

    The purpose of this report is to document the Multi-Function Waste Tank Facility (MWTF) Project position on the concrete mechanical properties needed to perform design/analysis calculations for the MWTF secondary concrete structure. This report provides a position on MWTF concrete properties for the Title 1 and Title 2 calculations. The scope of the report is limited to mechanical properties and does not include the thermophysical properties of concrete needed to perform heat transfer calculations. In the 1970's, a comprehensive series of tests were performed at Construction Technology Laboratories (CTL) on two different Hanford concrete mix designs. Statistical correlations of the CTL data were later generated by Pacific Northwest Laboratories (PNL). These test results and property correlations have been utilized in various design/analysis efforts of Hanford waste tanks. However, due to changes in the concrete design mix and the lower range of MWTF operating temperatures, plus uncertainties in the CTL data and PNL correlations, it was prudent to evaluate the CTL data base and PNL correlations, relative to the MWTF application, and develop a defendable position. The CTL test program for Hanford concrete involved two different mix designs: a 3 kip/sq in mix and a 4.5 kip/sq in mix. The proposed 28-day design strength for the MWTF tanks is 5 kip/sq in. In addition to this design strength difference, there are also differences between the CTL and MWTF mix design details. Also of interest, are the appropriate application of the MWTF concrete properties in performing calculations demonstrating ACI Code compliance. Mix design details and ACI Code issues are addressed in Sections 3.0 and 5.0, respectively. The CTL test program and PNL data correlations focused on a temperature range of 250 to 450 F. The temperature range of interest for the MWTF tank concrete application is 70 to 200 F.

  14. Evaluation of concrete recycling system efficiency for ready-mix concrete plants.

    PubMed

    Vieira, Luiz de Brito Prado; Figueiredo, Antonio Domingues de

    2016-10-01

    The volume of waste generated annually in concrete plants is quite large and has important environmental and economic consequences. The use of fresh concrete recyclers is an interesting way for the reuse of aggregates and water in new concrete production. This paper presents a study carried out for over one year by one of the largest ready-mix concrete producers in Brazil. This study focused on the evaluation of two recyclers with distinct material separation systems, herein referred to as drum-type and rotary sieve-type equipment. They were evaluated through characterization and monitoring test programs to verify the behaviour of recovered materials (aggregates, water, and slurry). The applicability of the recovered materials (water and aggregates) was also evaluated in the laboratory and at an industrial scale. The results obtained with the two types of recyclers used were equivalent and showed no significant differences. The only exception was in terms of workability. The drum-type recycler generated fewer cases that required increased pumping pressure. The analysis concluded that the use of untreated slurry is unfeasible because of its intense negative effects on the strength and workability of concrete. The reclaimed water, pre-treated to ensure that its density is less than 1.03g/cm(3), can be used on an industrial scale without causing any harm to the concrete. The use of recovered aggregates consequently induces an increase in water demand and cement consumption to ensure the workability conditions of concrete that is proportional to the concrete strength level. Therefore, the viability of their use is restricted to concretes with characteristic strengths lower than 25MPa.

  15. Concrete material characterization reinforced concrete tank structure Multi-Function Waste Tank Facility

    SciTech Connect

    Winkel, B.V.

    1995-03-03

    The purpose of this report is to document the Multi-Function Waste Tank Facility (MWTF) Project position on the concrete mechanical properties needed to perform design/analysis calculations for the MWTF secondary concrete structure. This report provides a position on MWTF concrete properties for the Title 1 and Title 2 calculations. The scope of the report is limited to mechanical properties and does not include the thermophysical properties of concrete needed to perform heat transfer calculations. In the 1970`s, a comprehensive series of tests were performed at Construction Technology Laboratories (CTL) on two different Hanford concrete mix designs. Statistical correlations of the CTL data were later generated by Pacific Northwest Laboratories (PNL). These test results and property correlations have been utilized in various design/analysis efforts of Hanford waste tanks. However, due to changes in the concrete design mix and the lower range of MWTF operating temperatures, plus uncertainties in the CTL data and PNL correlations, it was prudent to evaluate the CTL data base and PNL correlations, relative to the MWTF application, and develop a defendable position. The CTL test program for Hanford concrete involved two different mix designs: a 3 kip/in{sup 2} mix and a 4.5 kip/in{sup 2} mix. The proposed 28-day design strength for the MWTF tanks is 5 kip/in{sup 2}. In addition to this design strength difference, there are also differences between the CTL and MWTF mix design details. Also of interest, are the appropriate application of the MWTF concrete properties in performing calculations demonstrating ACI Code compliance. Mix design details and ACI Code issues are addressed in Sections 3.0 and 5.0, respectively. The CTL test program and PNL data correlations focused on a temperature range of 250 to 450 F. The temperature range of interest for the MWTF tank concrete application is 70 to 200 F.

  16. Lasers for the radioactive decontamination of concrete

    SciTech Connect

    Cannon, N.S.; Flesher, D.J.

    1993-10-01

    The use of lasers for removing radioactive contamination from concrete surfaces is being investigated at the US Department of Energy`s Hanford Site. A major advantage of a laser decontamination process is that no additional waste is generated. Test results using 50- and 600-W YAG (yttrium-aluminum-garnet) lasers have been extrapolated to more powerful commercially available units. The minimum removal rate for concrete in air is estimated at 420 cm{sup 2}/h (0.45 ft{sup 2}/h) to a depth of 0.64 cm (0.25 in.); underwater rates would be considerably reduced.

  17. Advanced Numerical Model for Irradiated Concrete

    SciTech Connect

    Giorla, Alain B.

    2015-03-01

    In this report, we establish a numerical model for concrete exposed to irradiation to address these three critical points. The model accounts for creep in the cement paste and its coupling with damage, temperature and relative humidity. The shift in failure mode with the loading rate is also properly represented. The numerical model for creep has been validated and calibrated against different experiments in the literature [Wittmann, 1970, Le Roy, 1995]. Results from a simplified model are shown to showcase the ability of numerical homogenization to simulate irradiation effects in concrete. In future works, the complete model will be applied to the analysis of the irradiation experiments of Elleuch et al. [1972] and Kelly et al. [1969]. This requires a careful examination of the experimental environmental conditions as in both cases certain critical information are missing, including the relative humidity history. A sensitivity analysis will be conducted to provide lower and upper bounds of the concrete expansion under irradiation, and check if the scatter in the simulated results matches the one found in experiments. The numerical and experimental results will be compared in terms of expansion and loss of mechanical stiffness and strength. Both effects should be captured accordingly by the model to validate it. Once the model has been validated on these two experiments, it can be applied to simulate concrete from nuclear power plants. To do so, the materials used in these concrete must be as well characterized as possible. The main parameters required are the mechanical properties of each constituent in the concrete (aggregates, cement paste), namely the elastic modulus, the creep properties, the tensile and compressive strength, the thermal expansion coefficient, and the drying shrinkage. These can be either measured experimentally, estimated from the initial composition in the case of cement paste, or back-calculated from mechanical tests on concrete. If some

  18. Prediction of creep of polymer concrete

    SciTech Connect

    Khristova, Yu.; Aniskevich, K.

    1995-11-01

    We studied the applicability of the phenomenological approach to the prediction of long-time creep of polymer concrete consisting of polyester binder with diabase filler and diabase aggregate. We discovered that the principles of temperature-time analogy, of moisture-time analogy, and of temperature-moisture-time analogy are applicable to the description of the diagrams of short-time creep and to the prediction of long-time creep of polymer concrete at different temperatures and constant moisture content of the material.

  19. Use of cactus in mortars and concrete

    SciTech Connect

    Chandra, S.; Eklund, L.; Villarreal, R.R.

    1998-01-01

    Natural polymers have been used in ancient times to improve the durability of lime-based mortars and concretes. The natural polymers used were locally available. In this work, cactus extract from Mexico has been tested in a Portland cement mortar. It is seen that cactus extract increases the plasticity of the mortar and improves water absorption and freeze-salt resistance. Calcium hydroxide produced by Portland cement hydration interacts with the components of cactus extract, polysaccharides or proteins, and forms complexes. It affects the crystallization process. Painting of the concrete with this extract has also shown improved water resistance.

  20. Concrete dam on the Bratsk hydroelectric station

    SciTech Connect

    Solov'eva, Z.I.

    1988-07-01

    The Bratsk concrete dam was designed and constructed with a sufficient degree of reliability. Settlement of the dam together with the powerhouse developed uniformly under the entire foundation. Two irreversible processes causing aging of the dam have been established by operating observations: leaching of the concrete and decompression of the contact zone of the foundation near the upstream face of the powerhouse sections. The decompression is due to the fact that the powerhouse sections are lighter than the spillway sections. At the present level this process can only be slowed by the combined use of grouting and drainage unloading.