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Sample records for reinforcement function design

  1. Function transformation without reinforcement.

    PubMed

    Tonneau, Franćois; Arreola, Fara; Martínez, Alma Gabriela

    2006-05-01

    In studies of function transformation, participants initially are taught to match stimuli in the presence of a contextual cue, X; the stimuli to be matched bear some formal relation to each other, for example, a relation of opposition or difference. In a second phase, the participants are taught to match arbitrary stimuli (say, A and B) in the presence of X. In a final test, A often displays behavioral functions that differ from those of B, and can be predicted from the nature of the relation associated with X in the initial training phase. Here we report function-transformation effects in the absence of selection responses and of their reinforcers. In three experiments with college students, exposure to relations of difference or identity modified the responses given to later stimuli. In Experiment 1, responses to a test stimulus A varied depending on preexposure to pairs of colors that were distinct from A but exemplified relations of difference or identity. In Experiment 2, a stimulus A acquired distinct functions, depending on its previous pairing with a contextual cue X that had itself been paired with identity or difference among colors. Experiment 3 confirmed the results of Experiment 2 with a modified design. Our data are consistent with the notion that relations of identity or difference can serve as stimuli for Pavlovian processes, and, in compound with other cues, produce apparent function-transformation effects. PMID:16776058

  2. Function Transformation without Reinforcement

    PubMed Central

    Tonneau, François; Arreola, Fara; Martínez, Alma Gabriela

    2006-01-01

    In studies of function transformation, participants initially are taught to match stimuli in the presence of a contextual cue, X; the stimuli to be matched bear some formal relation to each other, for example, a relation of opposition or difference. In a second phase, the participants are taught to match arbitrary stimuli (say, A and B) in the presence of X. In a final test, A often displays behavioral functions that differ from those of B, and can be predicted from the nature of the relation associated with X in the initial training phase. Here we report function-transformation effects in the absence of selection responses and of their reinforcers. In three experiments with college students, exposure to relations of difference or identity modified the responses given to later stimuli. In Experiment 1, responses to a test stimulus A varied depending on preexposure to pairs of colors that were distinct from A but exemplified relations of difference or identity. In Experiment 2, a stimulus A acquired distinct functions, depending on its previous pairing with a contextual cue X that had itself been paired with identity or difference among colors. Experiment 3 confirmed the results of Experiment 2 with a modified design. Our data are consistent with the notion that relations of identity or difference can serve as stimuli for Pavlovian processes, and, in compound with other cues, produce apparent function-transformation effects. PMID:16776058

  3. Reinforcement function design and bias for efficient learning in mobile robots

    SciTech Connect

    Touzet, C.; Santos, J.M.

    1998-06-01

    The main paradigm in sub-symbolic learning robot domain is the reinforcement learning method. Various techniques have been developed to deal with the memorization/generalization problem, demonstrating the superior ability of artificial neural network implementations. In this paper, the authors address the issue of designing the reinforcement so as to optimize the exploration part of the learning. They also present and summarize works relative to the use of bias intended to achieve the effective synthesis of the desired behavior. Demonstrative experiments involving a self-organizing map implementation of the Q-learning and real mobile robots (Nomad 200 and Khepera) in a task of obstacle avoidance behavior synthesis are described. 3 figs., 5 tabs.

  4. Automatic tuning of the reinforcement function

    SciTech Connect

    Touzet, C.; Santos, J.M.

    1997-12-31

    The aim of this work is to present a method that helps tuning the reinforcement function parameters in a reinforcement learning approach. Since the proposal of neural based implementations for the reinforcement learning paradigm (which reduced learning time and memory requirements to realistic values) reinforcement functions have become the critical components. Using a general definition for reinforcement functions, the authors solve, in a particular case, the so called exploration versus exploitation dilemma through the careful computation of the RF parameter values. They propose an algorithm to compute, during the exploration part of the learning phase, an estimate for the parameter values. Experiments with the mobile robot Nomad 200 validate their proposals.

  5. Optimal Reward Functions in Distributed Reinforcement Learning

    NASA Technical Reports Server (NTRS)

    Wolpert, David H.; Tumer, Kagan

    2000-01-01

    We consider the design of multi-agent systems so as to optimize an overall world utility function when (1) those systems lack centralized communication and control, and (2) each agents runs a distinct Reinforcement Learning (RL) algorithm. A crucial issue in such design problems is to initialize/update each agent's private utility function, so as to induce best possible world utility. Traditional 'team game' solutions to this problem sidestep this issue and simply assign to each agent the world utility as its private utility function. In previous work we used the 'Collective Intelligence' framework to derive a better choice of private utility functions, one that results in world utility performance up to orders of magnitude superior to that ensuing from use of the team game utility. In this paper we extend these results. We derive the general class of private utility functions that both are easy for the individual agents to learn and that, if learned well, result in high world utility. We demonstrate experimentally that using these new utility functions can result in significantly improved performance over that of our previously proposed utility, over and above that previous utility's superiority to the conventional team game utility.

  6. Providing Alternative Reinforcers to Facilitate Tolerance to Delayed Reinforcement Following Functional Communication Training

    ERIC Educational Resources Information Center

    Austin, Jillian E.; Tiger, Jeffrey H.

    2015-01-01

    The earliest stages of functional communication training (FCT) involve providing immediate and continuous reinforcement for a communicative response (FCR) that is functionally equivalent to the targeted problem behavior. However, maintaining immediate reinforcement is not practical, and the introduction of delays is associated with increased…

  7. Designing concrete EDS maglev guideways: Power losses in metallic reinforcement

    SciTech Connect

    Beto, D.; Plotkin, D.

    1997-05-01

    Conventional reinforced concrete designs will have to be altered when designing a guideway for a maglev using an electrodynamically suspended (EDS) propulsion system. This type of propulsion system generates large magnetic fields that will develop magnetically induced, circulating eddy currents in any conventional steel reinforcement in close proximity to the magnets. These eddy currents, if large enough, may produce significant power losses that could adversely effect operation of the system. This paper presents a method and explanation for civil engineers to use for estimating the power losses due to the presence of metallic reinforcement. This procedure may be used to help guide future designs in the selection and placement of reinforcing material.

  8. Treatment of Pica through Multiple Analyses of Its Reinforcing Functions.

    ERIC Educational Resources Information Center

    Piazza, Cathleen C.; Fisher, Wayne W.; Hanley, Gregory P.; LeBlanc, Linda A.; Worsdell, April S.; And Others

    1998-01-01

    A study conducted functional analyses of the pica of three young children. The pica of one participant was maintained by automatic reinforcement; that of the other two was multiply-controlled by social and automatic reinforcement. Preference and treatment analyses were used to address the automatic function of the pica. (Author/CR)

  9. Glass Fiber Reinforced Metal Pressure Vessel Design Guide

    NASA Technical Reports Server (NTRS)

    Landes, R. E.

    1972-01-01

    The Engineering Guide presents curves and general equations for safelife design of lightweight glass fiber reinforced (GFR) metal pressure vessels operating under anticipated Space Shuttle service conditions. The high composite vessel weight efficiency is shown to be relatively insensitive to shape, providing increased flexibility to designers establishing spacecraft configurations. Spheres, oblate speroids, and cylinders constructed of GFR Inconel X-750, 2219-T62 aluminum, and cryoformed 301 stainless steel are covered; design parameters and performance efficiencies for each configuration are compared at ambient and cryogenic temperature for an operating pressure range of 690 to 2760 N/sq cm (1000 to 4000 psi). Design variables are presented as a function of metal shell operating to sizing (proof) stress ratios for use with fracture mechanics data generated under a separate task of this program.

  10. The Effects Of Reinforcement Magnitude On Functional Analysis Outcomes

    PubMed Central

    2005-01-01

    The duration or magnitude of reinforcement has varied and often appears to have been selected arbitrarily in functional analysis research. Few studies have evaluated the effects of reinforcement magnitude on problem behavior, even though basic findings indicate that this parameter may affect response rates during functional analyses. In the current study, 6 children with autism or developmental disabilities who engaged in severe problem behavior were exposed to three separate functional analyses, each of which varied in reinforcement magnitude. Results of these functional analyses were compared to determine if a particular reinforcement magnitude was associated with the most conclusive outcomes. In most cases, the same conclusion about the functions of problem behavior was drawn regardless of the reinforcement magnitude. PMID:16033163

  11. Characterization and design of steel fiber reinforced shotcrete in tunnelling

    SciTech Connect

    Casanova, P.A.; Rossi, P.C.

    1995-12-31

    A design procedure of steel fiber reinforced shotcrete tunnel linings is proposed. It is based on the analysis of a cracked section. The tensile behavior of shotcrete after cracking is obtained by a uniaxial tension test on cored notched samples. As for usual reinforced concrete structures an interaction diagram (moment-axial load) is determined.

  12. Treatment of pica through multiple analyses of its reinforcing functions.

    PubMed Central

    Piazza, C C; Fisher, W W; Hanley, G P; LeBlanc, L A; Worsdell, A S; Lindauer, S E; Keeney, K M

    1998-01-01

    We conducted functional analyses of the pica of 3 participants. The pica of 1 participant appeared to be maintained by automatic reinforcement; that of the other 2 participants appeared to be multiply controlled by social and automatic reinforcement. Subsequent preference and treatment analyses were used to identify stimuli that would complete with the automatic function of pica for the 3 participants. These analyses also identified the specific aspect of oral stimulation that served as automatic reinforcement for 2 of the participants. In addition, functional analysis-based treatments were used to address the socially motivated components of 2 of the participants' pica. Results are discussed in terms of (a) the importance of using the results of functional analyses to develop treatments for pica and (b) the advantages of developing indirect analyses to identify specific sources of reinforcement for automatically reinforced behavior. PMID:9652098

  13. Reinforcement schedule thinning following treatment with functional communication training.

    PubMed Central

    Hanley, G P; Iwata, B A; Thompson, R H

    2001-01-01

    We evaluated four methods for increasing the practicality of functional communication training (FCT) by decreasing the frequency of reinforcement for alternative behavior. Three participants whose problem behaviors were maintained by positive reinforcement were treated successfully with FCT in which reinforcement for alternative behavior was initially delivered on fixed-ratio (FR) 1 schedules. One participant was then exposed to increasing delays to reinforcement under FR 1, a graduated fixed-interval (FI) schedule, and a graduated multiple-schedule arrangement in which signaled periods of reinforcement and extinction were alternated. Results showed that (a) increasing delays resulted in extinction of the alternative behavior, (b) the FI schedule produced undesirably high rates of the alternative behavior, and (c) the multiple schedule resulted in moderate and stable levels of the alternative behavior as the duration of the extinction component was increased. The other 2 participants were exposed to graduated mixed-schedule (unsignaled alternation between reinforcement and extinction components) and multiple-schedule (signaled alternation between reinforcement and extinction components) arrangements in which the durations of the reinforcement and extinction components were modified. Results obtained for these 2 participants indicated that the use of discriminative stimuli in the multiple schedule facilitated reinforcement schedule thinning. Upon completion of treatment, problem behavior remained low (or at zero), whereas alternative behavior was maintained as well as differentiated during a multiple-schedule arrangement consisting of a 4-min extinction period followed by a 1-min reinforcement period. PMID:11317985

  14. Facilitating Tolerance of Delayed Reinforcement during Functional Communication Training.

    ERIC Educational Resources Information Center

    Fisher, Wayne W.; Thompson, Rachel H.; Hagopian, Louis P.; Bowman, Lynn G.; Krug, Amy

    2000-01-01

    Three individuals with severe behavior disorders and mental retardation, whose destructive behaviors were being maintained by positive reinforcement, were treated using functional communication training with extinction. The case studies investigated techniques used to increase effectiveness of delayed reinforcement and to teach individuals with…

  15. Cohesive fracture model for functionally graded fiber reinforced concrete

    SciTech Connect

    Park, Kyoungsoo; Paulino, Glaucio H.; Roesler, Jeffery

    2010-06-15

    A simple, effective, and practical constitutive model for cohesive fracture of fiber reinforced concrete is proposed by differentiating the aggregate bridging zone and the fiber bridging zone. The aggregate bridging zone is related to the total fracture energy of plain concrete, while the fiber bridging zone is associated with the difference between the total fracture energy of fiber reinforced concrete and the total fracture energy of plain concrete. The cohesive fracture model is defined by experimental fracture parameters, which are obtained through three-point bending and split tensile tests. As expected, the model describes fracture behavior of plain concrete beams. In addition, it predicts the fracture behavior of either fiber reinforced concrete beams or a combination of plain and fiber reinforced concrete functionally layered in a single beam specimen. The validated model is also applied to investigate continuously, functionally graded fiber reinforced concrete composites.

  16. Design Guide for glass fiber reinforced metal pressure vessel

    NASA Technical Reports Server (NTRS)

    Landes, R. E.

    1973-01-01

    Design Guide has been prepared for pressure vessel engineers concerned with specific glass fiber reinforced metal tank design or general tank tradeoff study. Design philosophy, general equations, and curves are provided for safelife design of tanks operating under anticipated space shuttle service conditions.

  17. Democratic reinforcement: A principle for brain function

    NASA Astrophysics Data System (ADS)

    Stassinopoulos, Dimitris; Bak, Per

    1995-05-01

    We introduce a simple ``toy'' brain model. The model consists of a set of randomly connected, or layered integrate-and-fire neurons. Inputs to and outputs from the environment are connected randomly to subsets of neurons. The connections between firing neurons are strengthened or weakened according to whether the action was successful or not. Unlike previous reinforcement learning algorithms, the feedback from the environment is democratic: it affects all neurons in the same way, irrespective of their position in the network and independent of the output signal. Thus no unrealistic back propagation or other external computation is needed. This is accomplished by a global threshold regulation which allows the system to self-organize into a highly susceptible, possibly ``critical'' state with low activity and sparse connections between firing neurons. The low activity permits memory in quiescent areas to be conserved since only firing neurons are modified when new information is being taught.

  18. Designing with figer-reinforced plastics (planar random composites)

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1982-01-01

    The use of composite mechanics to predict the hygrothermomechanical behavior of planar random composites (PRC) is reviewed and described. These composites are usually made from chopped fiber reinforced resins (thermoplastics or thermosets). The hygrothermomechanical behavior includes mechanical properties, physical properties, thermal properties, fracture toughness, creep and creep rupture. Properties are presented in graphical form with sample calculations to illustrate their use. Concepts such as directional reinforcement and strip hybrids are described. Typical data that can be used for preliminary design for various PRCs are included. Several resins and molding compounds used to make PRCs are described briefly. Pertinent references are cited that cover analysis and design methods, materials, data, fabrication procedures and applications.

  19. Signal functions in delayed discriminative stimulus control by reinforcement sources.

    PubMed

    Kuroda, Toshikazu; Lattal, Kennon A

    2014-05-01

    The discriminative functions of the response-reinforcer relation may contribute to the changes in response rates that occur when reinforcement is delayed. These properties were investigated in three experiments with pigeons using a discrete-trials conditional discrimination procedure. A concurrent variable-interval schedule was arranged on two side keys during a sample component. The key peck that ended the schedule (the sample response) initiated a delay with either a stimulus present throughout the delay interval (full signal), a stimulus present only during the first second of the interval (partial signal), or no stimulus present (unsignaled delay). The delay was followed by a choice component where one alternative was reinforced if the left sample response produced the choice component and the other if the right sample response produced the choice component. Accuracy was high with a full signal; slightly lower with a partial signal; and lowest without a signal. The results parallel the effects of similar delays programmed in conventional reinforcement schedules. This in turn suggests a possible discriminative effect of the response-reinforcer relation in the control of behavior by (delayed) reinforcement. PMID:24700527

  20. Design and behavior of reinforced concrete beams strengthened with fiber-reinforced plastics (FRP)

    NASA Astrophysics Data System (ADS)

    El-Mihilmy, Mahmoud Tharwat

    A comprehensive investigation of the design and behavior of reinforced concrete beams strengthened with externally bonded FRP laminates has been conducted. The study has confirmed the applicability of the strain compatibility method for calculating the increased ultimate moment capacity of the repaired beams. An upper limit to the amount of FRP that can be added to a specific structure was recommended to ensure ductile behavior. Design charts to facilitate calculations of the ultimate moment capacity for reinforced concrete beams strengthened with FRP laminates were developed. The results of a subsequent parametric investigation indicate that strengthening reinforced concrete beams with FRP laminates can enhance their ultimate capacity by as much as three times the original strength, especially for beams with a low steel ratio. It was also determined that, increasing the concrete compressive strength and the FRP modulus of elasticity increases the beam ultimate flexural capacity significantly; however, the repaired beams are less ductile than the pre-repaired concrete beams. During the course of the study, it had been noticed that the current ACI recommended method for calculating deflections for ordinary reinforced concrete beams does not render an accurate estimate for reinforced concrete beams strengthened with FRP laminates. A simplified equation for predicting the deflection of reinforced concrete beams repaired with FRP was developed and verified with comparisons to experimental results. The effectiveness of strengthening an existing bridge with externally bonded FRP laminates was investigated through comprehensive static and dynamic finite element analyses. The results of these analyses correlate well with field load test results. The repaired girders exhibited an average reduction in reinforcing steel stresses of 11 percent and an average reduction in midspan girder deflections of 9 percent. The results of the study also indicated that existing methods for

  1. Design and fabrication of a boron reinforced intertank skirt

    NASA Technical Reports Server (NTRS)

    Henshaw, J.; Roy, P. A.; Pylypetz, P.

    1974-01-01

    Analytical and experimental studies were performed to evaluate the structural efficiency of a boron reinforced shell, where the medium of reinforcement consists of hollow aluminum extrusions infiltrated with boron epoxy. Studies were completed for the design of a one-half scale minimum weight shell using boron reinforced stringers and boron reinforced rings. Parametric and iterative studies were completed for the design of minimum weight stringers, rings, shells without rings and shells with rings. Computer studies were completed for the final evaluation of a minimum weight shell using highly buckled minimum gage skin. The detail design is described of a practical minimum weight test shell which demonstrates a weight savings of 30% as compared to an all aluminum longitudinal stiffened shell. Sub-element tests were conducted on representative segments of the compression surface at maximum stress and also on segments of the load transfer joint. A 10 foot long, 77 inch diameter shell was fabricated from the design and delivered for further testing.

  2. Designing bioinspired composite reinforcement architectures via 3D magnetic printing

    PubMed Central

    Martin, Joshua J.; Fiore, Brad E.; Erb, Randall M.

    2015-01-01

    Discontinuous fibre composites represent a class of materials that are strong, lightweight and have remarkable fracture toughness. These advantages partially explain the abundance and variety of discontinuous fibre composites that have evolved in the natural world. Many natural structures out-perform the conventional synthetic counterparts due, in part, to the more elaborate reinforcement architectures that occur in natural composites. Here we present an additive manufacturing approach that combines real-time colloidal assembly with existing additive manufacturing technologies to create highly programmable discontinuous fibre composites. This technology, termed as ‘3D magnetic printing', has enabled us to recreate complex bioinspired reinforcement architectures that deliver enhanced material performance compared with monolithic structures. Further, we demonstrate that we can now design and evolve elaborate reinforcement architectures that are not found in nature, demonstrating a high level of possible customization in discontinuous fibre composites with arbitrary geometries. PMID:26494282

  3. Modeling root reinforcement using root-failure Weibull survival function

    NASA Astrophysics Data System (ADS)

    Schwarz, M.; Giadrossich, F.; Cohen, D.

    2013-03-01

    Root networks contribute to slope stability through complicated interactions that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamic of root turnover, the quantification of root reinforcement on steep slope is challenging and consequently the calculation of slope stability as well. Although the considerable advances in root reinforcement modeling, some important aspect remain neglected. In this study we address in particular to the role of root strength variability on the mechanical behaviors of a root bundle. Many factors may contribute to the variability of root mechanical properties even considering a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw). The results show that, for both laboratory and field datasets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the tensile force and the elasticity of the roots are the most important equations, as well as the root distribution. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root reinforcement for

  4. MODELING FUNCTIONALLY GRADED INTERPHASE REGIONS IN CARBON NANOTUBE REINFORCED COMPOSITES

    NASA Technical Reports Server (NTRS)

    Seidel, G. D.; Lagoudas, D. C.; Frankland, S. J. V.; Gates, T. S.

    2006-01-01

    A combination of micromechanics methods and molecular dynamics simulations are used to obtain the effective properties of the carbon nanotube reinforced composites with functionally graded interphase regions. The multilayer composite cylinders method accounts for the effects of non-perfect load transfer in carbon nanotube reinforced polymer matrix composites using a piecewise functionally graded interphase. The functional form of the properties in the interphase region, as well as the interphase thickness, is derived from molecular dynamics simulations of carbon nanotubes in a polymer matrix. Results indicate that the functional form of the interphase can have a significant effect on all the effective elastic constants except for the effective axial modulus for which no noticeable effects are evident.

  5. Functionally Graded Nickel Matrix Alumina Reinforced Nanocomposites

    NASA Astrophysics Data System (ADS)

    Young, Austin; Farias, Stephen; Cammarata, Robert

    2013-03-01

    Hierarchical structured nanocomposites are of great interest particularly in the fields of defense, aeronautics, and metamaterials. Previous work has demonstrated the ability to create uniform nickel matrices embedded with aluminum oxide nanoparticles via electrodeposition using a rotating disk electrode (RDE). This process allows for controlled enhancement of yield strength without negatively affecting other properties. The speed of the RDE controls the rate of particle incorporation, and therefore, particle volume fraction. Hierarchical structures can be formed by simply changing the rotation rate during electrodeposition. This allows for controlled variations of composite structure throughout the material. Simply layered and functionally graded hierarchical materials have been produced using this method with structural resolution of the order of single microns. These layered structures produced unique mechanical properties, even exceeding those of uniformly dispersed composites.

  6. Analyses and design of underground reinforced plastic mortar pipelines

    SciTech Connect

    Abdel-Magid, B.M.

    1986-01-01

    A simplified design procedure for underground Reinforced Plastic Mortar (RPM) pipe is proposed. This procedure is based on finite-element analyses of the pipe-soil system and composite laminate analysis of the pipe. With the proposed method, the designer is able to select the best trench geometry and backfill conditions, to determine the construction effects, and to devise the constituent pipe materials according to the given installation conditions for a reliable and cost-effective design. Existing design methods of underground flexible pipes were evaluated. A thorough investigation of the problems encountered with the RPM pipe is made to study the possible modes and causes of failure. The new design method is based on a composite beam element model to account for the failure modes pertinent to fiberglass-reinforced plastic pipes. The design procedure and the required soil and pipe materials data are described. It is shown that simpler performance limits are needed and that the proposed design procedure can be fully implemented once these data are provided.

  7. Thermomechanical behavior of SBR reinforced with nanotubes functionalized with polyvinylpyridine

    NASA Astrophysics Data System (ADS)

    De Falco, A.; Lamanna, M.; Goyanes, S.; D'Accorso, N. B.; Fascio, M. L.

    2012-08-01

    The mechanical and thermal behavior of composites consisting on a styrene-butadiene rubber (SBR) matrix with a sulphur/accelerator system and multiwalled carbon nanotubes functionalized with poly-4-vinylpyridine (MWCNT-PVP) as reinforcement, were studied. The materials were tested with stress-strain tensile tests, DMTA and DSC for thermal properties. A strong increase in the plastic behavior with slight decrease of its elastic Modulus and Tg led to unexpected results.

  8. Fracture Behavior and Properties of Functionally Graded Fiber-Reinforced Concrete

    SciTech Connect

    Roesler, Jeffery; Bordelon, Amanda; Gaedicke, Cristian; Park, Kyoungsoo; Paulino, Glaucio

    2008-02-15

    In concrete pavements, a single concrete mixture design is selected to resist mechanical loading without attempting to adversely affect the concrete pavement shrinkage, ride quality, or noise attenuation. An alternative approach is to design distinct layers within the concrete pavement surface which have specific functions thus achieving higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCM) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain and synthetic fiber-reinforced concrete materials. Fracture parameters and the post-peak softening behavior were obtained for each FGCM beam configuration by the three point bending beam test. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCM signified similar crack initiation. The total fracture energy indicated improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and predicted the fracture behavior of proposed FGCM configurations and structures. This integrated approach (testing and modeling) demonstrates the viability of FGCM for designing layered concrete pavements system.

  9. Reinforcement Schedule Thinning Following Functional Communication Training: Review and Recommendations

    PubMed Central

    Hagopian, Louis P; Boelter, Eric W; Jarmolowicz, David P

    2011-01-01

    This paper extends the Tiger, Hanley, and Bruzek (2008) review of functional communication training (FCT) by reviewing the published literature on reinforcement schedule thinning following FCT. As noted by Tiger et al. and others, schedule thinning may be necessary when the newly acquired communication response occurs excessively, to the extent that reinforcing it consistently is not practical in the natural environment. We provide a review of this literature including a discussion of each of the more commonly used schedule arrangements used for this purpose, outcomes obtained, a description of methods for progressing toward the terminal schedule, and a description of supplemental treatment components aimed at maintaining low levels of problem behavior during schedule thinning. Recommendations for schedule thinning are then provided. Finally, conceptual issues related to the reemergence of problem behavior during schedule thinning and areas for future research are discussed. PMID:22532899

  10. Clinical experience with reinforced, anchored intramuscular electrodes for functional neuromuscular stimulation.

    PubMed

    Prochazka, A; Davis, L A

    1992-05-01

    Implanted intramuscular electrodes must remain functional for many years if functional neuromuscular stimulation (FNS) is to become a standard treatment in paralysed individuals. In initial trials we found that 5 of 11 coiled single-wire FNS electrodes implanted in 3 patients failed within 8 months. Consequently, we turned to a reinforced electrode comprising 2 multi-stranded, insulated wires tandem-wound on a prolene core and terminated by a prolene anchor or tine (after Mortimer et al., 1986, 1987). The electrodes were implanted with a translumbar aortogram needle, the teflon sheath of which enabled us to stimulate through the tip to guide placement. We have monitored the electrical and functional properties of 8 reinforced electrodes implanted in 2 incomplete quadriplegic patients over 22 months. Four of the electrodes were used for at least 1 h daily to exercise muscles or to provide FNS in gait. Electrical impedances, thresholds and elicited limb motion remained constant in all 8 electrodes over the test period. Disadvantages of the reinforced electrodes are (1) difficulty of eventual removal, and (2) risk of pathogenic infiltration is increased by the 3-filament structure (fortunately dense tissue encapsulation seems to mitigate infection). We conclude that tandem-wound, prolene-reinforced FNS electrodes are much more robust than previous single-coil designs and may form the basis for FNS devices of the future. PMID:1501502

  11. Feedback Functions, Optimization, and the Relation of Response Rate to Reinforcer Rate

    ERIC Educational Resources Information Center

    Soto, Paul L.; McDowell, Jack J.; Dallery, Jesse

    2006-01-01

    The present experiment arranged a series of inverted U-shaped feedback functions relating reinforcer rate to response rate to test whether responding was consistent with an optimization account or with a one-to-one relation of response rate to reinforcer rate such as linear system theory's rate equation or Herrnstein's hyperbola. Reinforcer rate…

  12. The Function of Direct and Vicarious Reinforcement in Human Learning.

    ERIC Educational Resources Information Center

    Owens, Carl R.; And Others

    The role of reinforcement has long been an issue in learning theory. The effects of reinforcement in learning were investigated under circumstances which made the information necessary for correct performance equally available to reinforced and nonreinforced subjects. Fourth graders (N=36) were given a pre-test of 20 items from the Peabody Picture…

  13. Analysis/design of strip reinforced random composites /strip hybrids/

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1978-01-01

    Results are described which were obtained by applying advanced analysis methods and composite mechanics to a strip-reinforced random composite square panel with fixed ends. This was done in order to illustrate the use of these methods for the apriori assessment of the composite panel when subjected to complex loading conditions. The panel was assumed to be of E-Glass/Random Composite. The strips were assumed to be of three advanced unidirectional composites to cover a range of low, intermediate, and high modulus stiffness. The panels were assumed to be subjected to complex loadings to assess their adequacy as load-carrying members in auto body, aircraft engine nacelle, and windmill blade applications. The results show that strip hybrid panels can be several times more structurally efficient than the random composite base materials. Some of the results are presented in graphical form and procedures are described for use of these graphs as guides for preliminary design of strip hybrids.

  14. Analysis/design of strip reinforced random composites (strip hybrids)

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Sinclair, J. H.

    1978-01-01

    Advanced analysis methods and composite mechanics were applied to a strip-reinforced random composite square panel with fixed ends to illustrate the use of these methods for the a priori assessment of the composite panel when subjected to complex loading conditions. The panel was assumed to be of E-glass random composite. The strips were assumed to be of three advanced unidirectional composites to cover a range of low, intermediate, and high modulus stiffness. The panels were assumed to be subjected to complex loadings to assess their adequacy as load-carrying members in auto body, aircraft engine nacelle and windmill blade applications. The results show that strip hybrid panels can be several times more structurally efficient than the random composite base materials. Some of the results are presented in graphical form and procedures are described for use of these graphs as guides for preliminary design of strip hybrids.

  15. Aramid nanofiber-functionalized graphene nanosheets for polymer reinforcement

    NASA Astrophysics Data System (ADS)

    Fan, Jinchen; Shi, Zixing; Zhang, Lu; Wang, Jialiang; Yin, Jie

    2012-10-01

    Aramid macroscale fibers, also called Kevlar fibers, exhibit extremely high mechanical performance. Previous studies have demonstrated that bulk aramid macroscale fibers can be effectively split into aramid nanofibers (ANFs) by dissolution in dimethylsulfoxide (DMSO) in the presence of potassium hydroxide (KOH). In this paper, we first introduced the ANFs into the structure of graphene nanosheets through non-covalent functionalization through π-π stacking interactions. Aramid nanofiber-functionalized graphene sheets (ANFGS) were successfully obtained by adding the graphene oxide (GO)/DMSO dispersion into the ANFs/DMSO solution followed by reduction with hydrazine hydrate. The ANFGS, with ANFs absorbed on the surface of the graphene nanosheets, can be easily exfoliated and dispersed in N-methyl-2-pyrrolidone (NMP). Through a combination of these two ultra-strong materials, ANFs and graphene nanosheets (GS), the resultant ANFGS can act as novel nanofillers for polymer reinforcement. We used the ANFGS as an additive for reinforcing the mechanical properties of poly(methyl methacrylate) (PMMA). With a loading of 0.7 wt% of the ANFGS, the tensile strength and Young's modulus of the ANFGS/PMMA composite film approached 63.2 MPa and 3.42 GPa, which are increases of ~84.5% and ~70.6%, respectively. The thermal stabilities of ANFGS/PMMA composite films were improved by the addition of ANFGS. Additionally, the transparencies of the ANFGS/PMMA composite films have a degree of UV-shielding due to the ultraviolet light absorption of the ANFs in the ANFGS.Aramid macroscale fibers, also called Kevlar fibers, exhibit extremely high mechanical performance. Previous studies have demonstrated that bulk aramid macroscale fibers can be effectively split into aramid nanofibers (ANFs) by dissolution in dimethylsulfoxide (DMSO) in the presence of potassium hydroxide (KOH). In this paper, we first introduced the ANFs into the structure of graphene nanosheets through non

  16. Design aid for shear strengthening of reinforced concrete T-joints using carbon fiber reinforced plastic composites

    NASA Astrophysics Data System (ADS)

    Gergely, Ioan

    The research presented in the present work focuses on the shear strengthening of beam column joints using carbon fiber composites, a material considered in seismic retrofit in recent years more than any other new material. These composites, or fiber reinforced polymers, offer huge advantages over structural steel reinforced concrete or timber. A few of these advantages are the superior resistance to corrosion, high stiffness to weight and strength to weight ratios, and the ability to control the material's behavior by selecting the orientation of the fibers. The design and field application research on reinforced concrete cap beam-column joints includes analytical investigations using pushover analysis; design of carbon fiber layout, experimental tests and field applications. Several beam column joints have been tested recently with design variables as the type of composite system, fiber orientation and the width of carbon fiber sheets. The surface preparation has been found to be critical for the bond between concrete and composite material, which is the most important factor in joint shear strengthening. The final goal of this thesis is to develop design aids for retrofitting reinforced concrete beam column joints. Two bridge bents were tested on the Interstate-15 corridor. One bent was tested in the as-is condition. Carbon fiber reinforced plastic composite sheets were used to externally reinforce the second bridge bent. By applying the composite, the displacement ductility has been doubled, and the bent overall lateral load capacity has been increased as well. The finite element model (using DRAIN-2DX) was calibrated to model the actual stiffness of the supports. The results were similar to the experimental findings.

  17. Aramid nanofiber-functionalized graphene nanosheets for polymer reinforcement.

    PubMed

    Fan, Jinchen; Shi, Zixing; Zhang, Lu; Wang, Jialiang; Yin, Jie

    2012-11-21

    Aramid macroscale fibers, also called Kevlar fibers, exhibit extremely high mechanical performance. Previous studies have demonstrated that bulk aramid macroscale fibers can be effectively split into aramid nanofibers (ANFs) by dissolution in dimethylsulfoxide (DMSO) in the presence of potassium hydroxide (KOH). In this paper, we first introduced the ANFs into the structure of graphene nanosheets through non-covalent functionalization through π-π stacking interactions. Aramid nanofiber-functionalized graphene sheets (ANFGS) were successfully obtained by adding the graphene oxide (GO)/DMSO dispersion into the ANFs/DMSO solution followed by reduction with hydrazine hydrate. The ANFGS, with ANFs absorbed on the surface of the graphene nanosheets, can be easily exfoliated and dispersed in N-methyl-2-pyrrolidone (NMP). Through a combination of these two ultra-strong materials, ANFs and graphene nanosheets (GS), the resultant ANFGS can act as novel nanofillers for polymer reinforcement. We used the ANFGS as an additive for reinforcing the mechanical properties of poly(methyl methacrylate) (PMMA). With a loading of 0.7 wt% of the ANFGS, the tensile strength and Young's modulus of the ANFGS/PMMA composite film approached 63.2 MPa and 3.42 GPa, which are increases of ∼84.5% and ∼70.6%, respectively. The thermal stabilities of ANFGS/PMMA composite films were improved by the addition of ANFGS. Additionally, the transparencies of the ANFGS/PMMA composite films have a degree of UV-shielding due to the ultraviolet light absorption of the ANFs in the ANFGS. PMID:23047662

  18. A Different Pontic Design for Fiber-Reinforced Composite Bridgeworks: A Clinical Report

    PubMed Central

    Kumbuloḡlu, Ovul; Özdemir, Niler; Aksoy, Gökhan; User, Atilla

    2007-01-01

    Objectives This clinical report describes a relatively simple but esthetic, non-invasive and functional prosthodontic treatment option for a patient with missing tooth. Methods A patient with a missing maxillary left canine was non-invasively treated with a fiber reinforced composite (FRC) bridgework with an all ceramic (Empress II, Ivoclar Vivadent, Schaan, Liech-tenstein) pontic design, using laboratory technique. Results The restoration has served the patient for 2 year, seemingly without discomfort, and it has not required any maintenance. The patient has kept up with his oral hygiene. Conclusions Although additional clinical experience is necessary, fiber-reinforced composite materials can be used in combination with a lithium disilicate ceramic material in fixed partial dentures. PMID:19212498

  19. Designing interventions that include delayed reinforcement: implications of recent laboratory research.

    PubMed Central

    Stromer, R; McComas, J J; Rehfeldt, R A

    2000-01-01

    The search for robust and durable interventions in everyday situations typically involves the use of delayed reinforcers, sometimes delivered well after a target behavior occurs. Integrating the findings from laboratory research on delayed reinforcement can contribute to the design and analysis of those applied interventions. As illustrations, we examine articles from the Journal of the Experimental Analysis of Behavior that analyzed delayed reinforcement with respect to response allocation (A. M. Williams & Lattal, 1999), stimulus chaining (B. A. Williams, 1999), and self-control (Jackson & Hackenberg, 1996). These studies help to clarify the conditions under which delayed reinforcement (a) exercises control of behavior, (b) entails conditioned reinforcement, and (c) displaces the effects of immediate reinforcement. The research has applied implications, including the development of positive social behavior and teaching people to make adaptive choices. DESCRIPTORS: delayed reinforcement, response allocation, stimulus chains, self-control, integration of basic and applied research PMID:11051582

  20. A Comparison of Function-Based Differential Reinforcement Interventions for Children Engaging in Disruptive Classroom Behavior

    ERIC Educational Resources Information Center

    LeGray, Matthew W.; Dufrene, Brad A.; Sterling-Turner, Heather; Olmi, D. Joe; Bellone, Katherine

    2010-01-01

    This study provides a direct comparison of differential reinforcement of other behavior (DRO) and differential reinforcement of alternative behavior (DRA). Participants included three children in center-based classrooms referred for functional assessments due to disruptive classroom behavior. Functional assessments included interviews and brief…

  1. Off-policy reinforcement learning for H∞ control design.

    PubMed

    Luo, Biao; Wu, Huai-Ning; Huang, Tingwen

    2015-01-01

    The H∞ control design problem is considered for nonlinear systems with unknown internal system model. It is known that the nonlinear H∞ control problem can be transformed into solving the so-called Hamilton-Jacobi-Isaacs (HJI) equation, which is a nonlinear partial differential equation that is generally impossible to be solved analytically. Even worse, model-based approaches cannot be used for approximately solving HJI equation, when the accurate system model is unavailable or costly to obtain in practice. To overcome these difficulties, an off-policy reinforcement leaning (RL) method is introduced to learn the solution of HJI equation from real system data instead of mathematical system model, and its convergence is proved. In the off-policy RL method, the system data can be generated with arbitrary policies rather than the evaluating policy, which is extremely important and promising for practical systems. For implementation purpose, a neural network (NN)-based actor-critic structure is employed and a least-square NN weight update algorithm is derived based on the method of weighted residuals. Finally, the developed NN-based off-policy RL method is tested on a linear F16 aircraft plant, and further applied to a rotational/translational actuator system. PMID:25532162

  2. Design of Rock Slope Reinforcement: An Himalayan Case Study

    NASA Astrophysics Data System (ADS)

    Tiwari, Gaurav; Latha, Gali Madhavi

    2016-06-01

    The stability analysis of the two abutment slopes of a railway bridge proposed at about 359 m above the ground level, crossing a river and connecting two hill faces in the Himalayas, India, is presented. The bridge is located in a zone of high seismic activity. The rock slopes are composed of a heavily jointed rock mass and the spacing, dip and dip direction of joint sets are varying at different locations. Geological mapping was carried out to characterize all discontinuities present along the slopes. Laboratory and field investigations were conducted to assess the geotechnical properties of the intact rock, rock mass and joint infill. Stability analyses of these rock slopes were carried out using numerical programmes. Loads from the foundations resting on the slopes and seismic accelerations estimated from site-specific ground response analysis were considered. The proposed slope profile with several berms between successive foundations was simulated in the numerical model. An equivalent continuum approach with Hoek and Brown failure criterion was initially used in a finite element model to assess the global stability of the slope abutments. In the second stage, finite element analysis of rock slopes with all joint sets with their orientations, spacing and properties explicitly incorporated into the numerical model was taken up using continuum with joints approach. It was observed that the continuum with joints approach was able to capture the local failures in some of the slope sections, which were verified using wedge failure analysis and stereographic projections. Based on the slope deformations and failure patterns observed from the numerical analyses, rock anchors were designed to achieve the target factors of safety against failure while keeping the deformations within the permissible limits. Detailed design of rock anchors and comparison of the stability of slopes with and without reinforcement are presented.

  3. Context transfer in reinforcement learning using action-value functions.

    PubMed

    Mousavi, Amin; Nadjar Araabi, Babak; Nili Ahmadabadi, Majid

    2014-01-01

    This paper discusses the notion of context transfer in reinforcement learning tasks. Context transfer, as defined in this paper, implies knowledge transfer between source and target tasks that share the same environment dynamics and reward function but have different states or action spaces. In other words, the agents learn the same task while using different sensors and actuators. This requires the existence of an underlying common Markov decision process (MDP) to which all the agents' MDPs can be mapped. This is formulated in terms of the notion of MDP homomorphism. The learning framework is Q-learning. To transfer the knowledge between these tasks, the feature space is used as a translator and is expressed as a partial mapping between the state-action spaces of different tasks. The Q-values learned during the learning process of the source tasks are mapped to the sets of Q-values for the target task. These transferred Q-values are merged together and used to initialize the learning process of the target task. An interval-based approach is used to represent and merge the knowledge of the source tasks. Empirical results show that the transferred initialization can be beneficial to the learning process of the target task. PMID:25610457

  4. Design criteria for pultruded fiber-reinforced polymer composite columns

    NASA Astrophysics Data System (ADS)

    Choi, Yeol

    This dissertation investigated the behavior of pultruded fiber-reinforced polymer (FRP) composite columns under extensive time-independent short-term and time-dependent long-term experiments. Based on the experimental results, analytical studies were performed to propose a design approach for pultruded FRP composite columns. In the time-independent short-term tests, a total of 100 tests on wide flange, I-shape and box section columns were selected to develop the empirical column strength equation. All column tests were performed with pinned-pinned end conditions using either a 30 feet reaction frame or a MTS machine depending on the column length. The experimental results from short-term column tests provided valuable realistic information, such as the ultimate column capacity, failure mode, and column strength equation for pultruded FRP composite columns subjected to axial compression. To develop empirical column strength equation, ultimate column capacity at failure may be examined by plotting of the ultimate compressive stress versus effective slenderness ratio, and then nondimensionalize the ultimate compressive stress and slenderness ratio to compare columns having different cross sections. Finally, a set of empirical column strength equations of FRP composite column was developed from the column strength curves using curve-fitting technique. In the time-dependent long-term creep tests, a total of 4 box and 4 wide flange section columns were tested to investigate time-dependent deformation of pultruded FRP composite columns. The cross-section used in the investigation is 4 in. x 4 in. x 1/4 in. (100 mm x 100 mm x 6.4 mm) and length is 4 feet (1.2 m) with box and wide flange sections. Creep tests were carried out at four different loading levels; 20, 30, 40 and 50 percents of the ultimate column strength from the short-term column tests. The axial time-dependent deformation under sustained loading was monitored for time duration up to 2,500 hours. The

  5. Design and analysis of a novel latch system implementing fiber-reinforced composite materials

    NASA Astrophysics Data System (ADS)

    Guevara Arreola, Francisco Javier

    in the load-displacement slopes while the percentage of glass fiber increased. In the other hand, results showed that a detent made of only glass fiber layers was preferable than a carbon-glass fiber hybrid detent due to the high stresses shown in carbon fiber layers. Ultimately, forkbolt and detent were redesigned according to their functionality and test results. It was observed that the new design was stiffer than the original by showing a steeper load-displacement curve. Subsequently, an experimental procedure was performed in order to correlate computational model results. Fiber-reinforced composite forkbolt and detent were waterjet cut from a composite laminate manufactured by Vacuum Assisted Resin Transfer Molding (VART) process. Then, samples were tested according to the computational model. Six testing sample combinations of forkbolt and detent were tested including the top three woven iterations forkbolts from the computational model paired with woven and unidirectional glass fiber detents. Test results showed a stiffness drop of 15% when the carbon fiber percentage decreases from 100% to 75%. Also, it was observed that woven glass fiber detent was superior to the unidirectional glass fiber detent by presenting a forkbolt-detent stiffness 38% higher. Moreover, the new design of forkbolt and detent were tested showing a stiffness increment of 29%. Furthermore, it was observed that fiber-reinforced composite forkbolt and detent did not reach the desired load of 5000 N. However, the redesigned forkbolt made of 100% woven carbon fiber and the redesign detent made of 100% woven glass fiber were close to reach that load. The design review based on test results performed (DRBTR) showed that components did not fail where the computational model concluded to be the areas with the highest maximum principal stress. In contrast to the computational model, all samples failed at the contact area between forkbolt and detent.

  6. Efficient Load Transfer to Functionalized Carbon Nanotubes as Reinforcement in Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Chakoli, Ali Nabipour; Cai, Wei; Jiehe, Sui; Feng, Jiang Tao

    Multiwalled carbon nanotubes (MWCNTs) grafted with poly(L-lactide-e-caprolactone) (PCLA) were synthesized by in situ ring opening polymerization and used as a reinforcement for neat PCLA. The analyzed data revealed that the applied tensile load on the composite was transferred to the functionalized MWCNTs, leading to a strain failure of the MWCNTs rather than an adhesive failure between the MWCNTs and the matrix. In comparison between the functionalized and pristine MWCNTs, as reinforcement materials for PCLA random copolymers (80% L-lactide (LA), 20% e-caprolactone (CL)) (PCLAR80), the functionalized MWCNTs are more effective reinforcement materials than pristine MWCNTs. In comparison with the neat PCLAR80, the increasing in tensile strength (28.03%) and elongation at failure (49.6%) when functionalized MWCNT loading reaches 1.0 wt%, indicate that an effective reinforcement of the MWCNT-OH-g-PCLA.

  7. Circular Functions Based Comprehensive Analysis of Plastic Creep Deformations in the Fiber Reinforced Composites

    NASA Astrophysics Data System (ADS)

    Monfared, Vahid

    2016-06-01

    Analytically based model is presented for behavioral analysis of the plastic deformations in the reinforced materials using the circular (trigonometric) functions. The analytical method is proposed to predict creep behavior of the fibrous composites based on basic and constitutive equations under a tensile axial stress. New insight of the work is to predict some important behaviors of the creeping matrix. In the present model, the prediction of the behaviors is simpler than the available methods. Principal creep strain rate behaviors are very noteworthy for designing the fibrous composites in the creeping composites. Analysis of the mentioned parameter behavior in the reinforced materials is necessary to analyze failure, fracture, and fatigue studies in the creep of the short fiber composites. Shuttles, spaceships, turbine blades and discs, and nozzle guide vanes are commonly subjected to the creep effects. Also, predicting the creep behavior is significant to design the optoelectronic and photonic advanced composites with optical fibers. As a result, the uniform behavior with constant gradient is seen in the principal creep strain rate behavior, and also creep rupture may happen at the fiber end. Finally, good agreements are found through comparing the obtained analytical and FEM results.

  8. A Robust Reinforcement Learning Control Design Method for Nonlinear System with Partially Unknown Structure

    NASA Astrophysics Data System (ADS)

    Nakano, Kazuhiro; Obayashi, Masanao; Kuremoto, Takashi; Kobayashi, Kunikazu

    We propose a robust control system which has robustness for disturbance and can deal with a nonlinear system with partially unknown structure by fusing reinforcement learning and robust control theory. First, we solved an optimal control problem without using unknown part of functions of the system, using neural network and the repetition learning of reinforcement learning algorithm. Second, we built the robust reinforcement learning control system which permits uncertainty and has robustness for disturbance by fusing the idea of H infinity control theory with above system.

  9. Reinforcement learning controller design for affine nonlinear discrete-time systems using online approximators.

    PubMed

    Yang, Qinmin; Jagannathan, Sarangapani

    2012-04-01

    In this paper, reinforcement learning state- and output-feedback-based adaptive critic controller designs are proposed by using the online approximators (OLAs) for a general multi-input and multioutput affine unknown nonlinear discretetime systems in the presence of bounded disturbances. The proposed controller design has two entities, an action network that is designed to produce optimal signal and a critic network that evaluates the performance of the action network. The critic estimates the cost-to-go function which is tuned online using recursive equations derived from heuristic dynamic programming. Here, neural networks (NNs) are used both for the action and critic whereas any OLAs, such as radial basis functions, splines, fuzzy logic, etc., can be utilized. For the output-feedback counterpart, an additional NN is designated as the observer to estimate the unavailable system states, and thus, separation principle is not required. The NN weight tuning laws for the controller schemes are also derived while ensuring uniform ultimate boundedness of the closed-loop system using Lyapunov theory. Finally, the effectiveness of the two controllers is tested in simulation on a pendulum balancing system and a two-link robotic arm system. PMID:21947529

  10. Microwave Heating of Functionalized Graphene Nanoribbons in Thermoset Polymers for Wellbore Reinforcement.

    PubMed

    Kim, Nam Dong; Metzger, Andrew; Hejazi, Vahid; Li, Yilun; Kovalchuk, Anton; Lee, Seoung-Ki; Ye, Ruquan; Mann, Jason A; Kittrell, Carter; Shahsavari, Rouzbeh; Tour, James M

    2016-05-25

    Here, we introduce a systematic strategy to prepare composite materials for wellbore reinforcement using graphene nanoribbons (GNRs) in a thermoset polymer irradiated by microwaves. We show that microwave absorption by GNRs functionalized with poly(propylene oxide) (PPO-GNRs) cured the composite by reaching 200 °C under 30 W of microwave power. Nanoscale PPO-GNRs diffuse deep inside porous sandstone and dramatically enhance the mechanics of the entire structure via effective reinforcement. The bulk and the local mechanical properties measured by compression and nanoindentation mechanical tests, respectively, reveal that microwave heating of PPO-GNRs and direct polymeric curing are major reasons for this significant reinforcement effect. PMID:27140722

  11. Covalent cum noncovalent functionalizations of carbon nanotubes for effective reinforcement of a solution cast composite film.

    PubMed

    Yuan, Wei; Chan-Park, Mary B

    2012-04-01

    Although carbon nanotubes have impressive tensile properties, exploiting these properties in composites, especially those made by the common solution casting technique, seems to be elusive thus far. The reasons could be partly due to the poor nanotube dispersion and the weak nanotube/matrix interface. To solve this dual pronged problem, we combine noncovalent and covalent functionalizations of nanotubes in a single system by the design and application of a novel dispersant, hydroxyl polyimide-graft-bisphenol A diglyceryl acrylate (PI(OH)-BDA), and use them with epoxidized single-walled carbon nanotubes (O-SWNTs). Our novel PI(OH)-BDA dispersant functionalizes the nanotubes noncovalently to achieve good dispersion of the nanotubes because of the strong π-π interaction due to main chain and steric hindrance of the BDA side chain. PI(OH)-BDA also functionalizes O-SWNTs covalently because it reacts with epoxide groups on the nanotubes, as well as the cyanate ester (CE) matrix used. The resulting solution-cast CE composites show 57%, 71%, and 124% increases in Young's modulus, tensile strength, and toughness over neat CE. These values are higher than those of composites reinforced with pristine SWNTs, epoxidized SWNTs, and pristine SWNTs dispersed with PI(OH)-BDA. The modulus and strength increase per unit nanotube weight fraction, i.e., dE/dW(NT) and dσ/dW(NT), are 175 GPa and 7220 MPa, respectively, which are significantly higher than those of other nanotube/thermosetting composites (22-70 GPa and 140-3540 MPa, respectively). Our study indicates that covalent cum noncovalent functionalization of nanotubes is an effective tool for improving both the nanotube dispersion and nanotube/matrix interfacial interaction, resulting in significantly improved mechanical reinforcement of the solution-cast composites. PMID:22432973

  12. Further Evaluations of Functional Communication Training and Chained Schedules of Reinforcement to Treat Multiple Functions of Challenging Behavior

    ERIC Educational Resources Information Center

    Falcomata, Terry S.; Muething, Colin S.; Gainey, Summer; Hoffman, Katherine; Fragale, Christina

    2013-01-01

    We evaluated functional communication training (FCT) combined with a chained schedule of reinforcement procedure for the treatment of challenging behavior exhibited by two individuals diagnosed with Asperger syndrome and autism. Following functional analyses that suggested that challenging behavior served multiple functions for both participants,…

  13. Design synthesis of a boron/epoxy reinforced metal shear web.

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.

    1972-01-01

    An advanced composite shear web design concept has been developed for the Space Shuttle Orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad, boron/epoxy plate with vertical boron/epoxy reinforced stiffeners. Baseline composite and titanium shear resistant designs are compared; the composite concept is 28% lighter than the titanium web. Element test results show the metal cladding effectively reinforces critical composite load transfer and fastener hole areas making the composite web concept practical for other shear structure applications.-

  14. Plant Stems: Functional Design and Mechanics

    NASA Astrophysics Data System (ADS)

    Speck, Thomas; Burgert, Ingo

    2011-08-01

    Plant stems are one of nature's most impressive mechanical constructs. Their sophisticated hierarchical structure and multifunctionality allow trees to grow more than 100 m tall. This review highlights the advanced mechanical design of plant stems from the integral level of stem structures down to the fiber-reinforced-composite character of the cell walls. Thereby we intend not only to provide insight into structure-function relationships at the individual levels of hierarchy but to further discuss how growth forms and habits of plant stems are closely interrelated with the peculiarities of their tissue and cell structure and mechanics. This concept is extended to a further key feature of plants, namely, adaptive growth as a reaction to mechanical perturbation and/or changing environmental conditions. These mechanical design principles of plant stems can serve as concept generators for advanced biomimetic materials and may inspire materials and engineering sciences research.

  15. Functionalizing Designer DNA Crystals

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, Arun Richard

    nucleotides is usually pH dependent (pH < 6) four different TFOs were examined: TFO-1 was unmodified while TFOs 2-4 contained additional stabilizing analogues capable of extending triplex formation to pH 7. In addition, each of the TFOs contained a Cy5 dye at the 5'-end of the oligonucleotide to aid in characterization of TFO binding - crystals were obtained with all four variations of TFOs. Formation of DNA triplex in the motif was characterized by an electrophoretic mobility shift assay (EMSA), UV melting studies and FRET. Crystals containing TFO-1 (unmodified) and TFO-2 (with 2'-amino ethoxy modification) were isolated and flash-frozen in liquid nitrogen for X-ray data collection at beam line NSLS-X25. X-ray data was also collected for crystals of the 3-turn triangle without any TFO bound to it. Difference maps were done between the crystals with TFO against the one without to identify any additional electron density corresponding to the third strand in the triplex binding region. The data from the crystal containing TFO-2 was used to further analyze if the additional density can match the expected position of the TFO on the triangle motif. Since the additional density did not correspond to the entire binding region, 2Fo-Fc, 3Fo-2Fc and 4Fo-3Fc maps were done to check for missing pieces of the electron density. From the resulting 2Fo-Fc map, the asymmetric unit from the 3-turn triangle (31-bp duplex model based on previous structure 3UBI) was inserted into the density as a reference. However, the electron density corresponding to the TFO was still not continuous throughout the 13-nt triplex binding region and allowed only a partial fit of the TFO. The third nucleotide in positions 1, 3, 4, 6, 7 were fit into the density in the major groove of the underlying duplex with proper triplex configuration. The third chapter describes the triplex approach to position a functional group (the UV cross-linking agent psoralen) within a pre-formed DNA motif. Triplex formation and

  16. A constitutive function for the heat flux in short-fiber-reinforced composites

    NASA Astrophysics Data System (ADS)

    Herrmann, Heiko

    2015-12-01

    A constitutive function for heat flux in short-fiber-reinforced composites is developed. The fiber orientation distribution is considered using second-order orientation tensor; therefore, the constitutive function for the heat flux will depend on the orientation tensor. The resulting orthotropic equation is discussed also in the context of energy efficiency of buildings.

  17. A numerical approach for the design of multiscale fibre-reinforced cementitious composites

    NASA Astrophysics Data System (ADS)

    Montero-Chacón, Francisco; Schlangen, Erik; Cifuentes, Héctor; Medina, Fernando

    2015-10-01

    In the present work, a numerical framework for the design of new multiscale fibre-reinforced cementitious composites is presented. This is accomplished by covering three different length scales, namely the micro-, meso- and macroscale. At the microscale (here defined as ~1 mm), an enhanced fibre-reinforced lattice model is presented for the simulation of strain hardening cementitious composites. On the other hand, the analysis of fibre-reinforced concrete is performed at the mesoscale (~10 mm) by means of a novel lattice-particle model. The main variables in both models are the fibre dimensions (i.e. length and diameter), the fibre volume content and the fibre-matrix bond behaviour. Their contribution to the global mechanical properties is discussed in details. Finally, the structural characterisation of the fibre-reinforced cementitious composites (FRCC) is carried out by means of a hierarchical numerical homogenisation of the material behaviour, integrating the information obtained from lower scales into the macroscale problem (~1 m). The macroscopic response of the resulting material is characterised via three-point bending tests using a continuum damage plastic model. Although the described lattice models can be used independently as design tools in fibre cement-based composites at the micro- or mesoscale, the multiscale procedure described in this paper allows for the development of new types of FRCC by considering the effect of the multiple-scale fibre-reinforcement.

  18. The IMAGEN study: reinforcement-related behaviour in normal brain function and psychopathology.

    PubMed

    Schumann, G; Loth, E; Banaschewski, T; Barbot, A; Barker, G; Büchel, C; Conrod, P J; Dalley, J W; Flor, H; Gallinat, J; Garavan, H; Heinz, A; Itterman, B; Lathrop, M; Mallik, C; Mann, K; Martinot, J-L; Paus, T; Poline, J-B; Robbins, T W; Rietschel, M; Reed, L; Smolka, M; Spanagel, R; Speiser, C; Stephens, D N; Ströhle, A; Struve, M

    2010-12-01

    A fundamental function of the brain is to evaluate the emotional and motivational significance of stimuli and to adapt behaviour accordingly. The IMAGEN study is the first multicentre genetic-neuroimaging study aimed at identifying the genetic and neurobiological basis of individual variability in impulsivity, reinforcer sensitivity and emotional reactivity, and determining their predictive value for the development of frequent psychiatric disorders. Comprehensive behavioural and neuropsychological characterization, functional and structural neuroimaging and genome-wide association analyses of 2000 14-year-old adolescents are combined with functional genetics in animal and human models. Results will be validated in 1000 adolescents from the Canadian Saguenay Youth Study. The sample will be followed up longitudinally at the age of 16 years to investigate the predictive value of genetics and intermediate phenotypes for the development of frequent psychiatric disorders. This review describes the strategies the IMAGEN consortium used to meet the challenges posed by large-scale multicentre imaging-genomics investigations. We provide detailed methods and Standard Operating Procedures that we hope will be helpful for the design of future studies. These include standardization of the clinical, psychometric and neuroimaging-acquisition protocols, development of a central database for efficient analyses of large multimodal data sets and new analytic approaches to large-scale genetic neuroimaging analyses. PMID:21102431

  19. COMPSIZE - PRELIMINARY DESIGN METHOD FOR FIBER REINFORCED COMPOSITE STRUCTURES

    NASA Technical Reports Server (NTRS)

    Eastlake, C. N.

    1994-01-01

    The Composite Structure Preliminary Sizing program, COMPSIZE, is an analytical tool which structural designers can use when doing approximate stress analysis to select or verify preliminary sizing choices for composite structural members. It is useful in the beginning stages of design concept definition, when it is helpful to have quick and convenient approximate stress analysis tools available so that a wide variety of structural configurations can be sketched out and checked for feasibility. At this stage of the design process the stress/strain analysis does not need to be particularly accurate because any configurations tentatively defined as feasible will later be analyzed in detail by stress analysis specialists. The emphasis is on fast, user-friendly methods so that rough but technically sound evaluation of a broad variety of conceptual designs can be accomplished. Analysis equations used are, in most cases, widely known basic structural analysis methods. All the equations used in this program assume elastic deformation only. The default material selection is intermediate strength graphite/epoxy laid up in a quasi-isotropic laminate. A general flat laminate analysis subroutine is included for analyzing arbitrary laminates. However, COMPSIZE should be sufficient for most users to presume a quasi-isotropic layup and use the familiar basic structural analysis methods for isotropic materials, after estimating an appropriate elastic modulus. Homogeneous materials can be analyzed as simplified cases. The COMPSIZE program is written in IBM BASICA. The program format is interactive. It was designed on an IBM Personal Computer operating under DOS with a central memory requirement of approximately 128K. It has been implemented on an IBM compatible with GW-BASIC under DOS 3.2. COMPSIZE was developed in 1985.

  20. The Effects of a Local Negative Feedback Function between Choice and Relative Reinforcer Rate

    ERIC Educational Resources Information Center

    Davison, Michael; Elliffe, Douglas; Marr, M. Jackson

    2010-01-01

    Four pigeons were trained on two-key concurrent variable-interval schedules with no changeover delay. In Phase 1, relative reinforcers on the two alternatives were varied over five conditions from 0.1 to 0.9. In Phases 2 and 3, we instituted a molar feedback function between relative choice in an interreinforcer interval and the probability of…

  1. Effects of Noncontingent Reinforcement and Functional Communication Training on Problem Behavior and Mands

    ERIC Educational Resources Information Center

    Doughty, Shannon S.; Anderson, Cynthia M.

    2006-01-01

    Two children with developmental delays and a history of problem behavior participated in this study to examine the efficacy of combining two treatments demonstrated to reduce problem behavior: noncontingent reinforcement and functional communication training. At issue was whether the noncontingent delivery of an alternative preferred stimulus and…

  2. Functional Communication Training without Extinction Using Concurrent Schedules of Differing Magnitudes of Reinforcement in Classrooms

    ERIC Educational Resources Information Center

    Davis, Dawn H.; Fredrick, Laura D.; Alberto, Paul A.; Gama, Roberto

    2012-01-01

    This study investigated the effects of functional communication training (FCT) implemented with concurrent schedules of differing magnitudes of reinforcement in lieu of extinction to reduce inappropriate behaviors and increase alternative mands. Participants were four adolescent students diagnosed with severe emotional and behavior disorders…

  3. Web platform for functional design

    NASA Astrophysics Data System (ADS)

    Dijmarescu, M. R.; Dijmarescu, M. C.

    2015-11-01

    Today's global competitive trends, especially those related to industries, determine a much higher degree of pressure and demands for substantial innovation driven improvements, flexible and time sensitive solutions. Improving and optimizing the design activity by shortening its timeline and maintaining a high quality level for its output have become the main success factors. The evolution of design activity is strongly related to the evolution of education and research made in the design field. Thus, the development of web tools which can contain knowledge about mechanical products functionality and structure may be an important achievement for the education and industry. This paper presents a web platform which contains functional-constructive knowledge in the area of mechanical design field and was developed to support design activity. The proposed web tool can provide any user, even one without background in design theory, information about the functionality of products and the way it is related to the product structure.

  4. Functionalizing Designer DNA Crystals

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, Arun Richard

    nucleotides is usually pH dependent (pH < 6) four different TFOs were examined: TFO-1 was unmodified while TFOs 2-4 contained additional stabilizing analogues capable of extending triplex formation to pH 7. In addition, each of the TFOs contained a Cy5 dye at the 5'-end of the oligonucleotide to aid in characterization of TFO binding - crystals were obtained with all four variations of TFOs. Formation of DNA triplex in the motif was characterized by an electrophoretic mobility shift assay (EMSA), UV melting studies and FRET. Crystals containing TFO-1 (unmodified) and TFO-2 (with 2'-amino ethoxy modification) were isolated and flash-frozen in liquid nitrogen for X-ray data collection at beam line NSLS-X25. X-ray data was also collected for crystals of the 3-turn triangle without any TFO bound to it. Difference maps were done between the crystals with TFO against the one without to identify any additional electron density corresponding to the third strand in the triplex binding region. The data from the crystal containing TFO-2 was used to further analyze if the additional density can match the expected position of the TFO on the triangle motif. Since the additional density did not correspond to the entire binding region, 2Fo-Fc, 3Fo-2Fc and 4Fo-3Fc maps were done to check for missing pieces of the electron density. From the resulting 2Fo-Fc map, the asymmetric unit from the 3-turn triangle (31-bp duplex model based on previous structure 3UBI) was inserted into the density as a reference. However, the electron density corresponding to the TFO was still not continuous throughout the 13-nt triplex binding region and allowed only a partial fit of the TFO. The third nucleotide in positions 1, 3, 4, 6, 7 were fit into the density in the major groove of the underlying duplex with proper triplex configuration. The third chapter describes the triplex approach to position a functional group (the UV cross-linking agent psoralen) within a pre-formed DNA motif. Triplex formation and

  5. The Effects of the Absence of an Adult on the Emergence of Conditioned Reinforcement as a Function of Observation in Preschool Age Children

    ERIC Educational Resources Information Center

    Zrinzo, Michelle L.

    2010-01-01

    I tested the effects of the absence of an adult on the observational conditioning effect (Greer & Singer-Dudek, 2008). Neutral stimuli (metal washers) did not function to reinforce performance or learning tasks for three preschool age children as determined by a counterbalanced reversal design for the pre-intervention performance tasks and…

  6. The Clinical Utility of Two Reinforcement Preference Assessment Techniques: A Comparison of Duration of Assessment and Identification of Functional Reinforcers

    ERIC Educational Resources Information Center

    Lanner, Traci; Nichols, Brandon; Field, Sean; Hanson, Jennifer; Zane, Thomas

    2009-01-01

    In order to maximize the learning of skills, it is crucial that the most powerful reinforcement be used. Research describes several different methods of reinforcement preference assessments, including forced choice, free-operant, and multiple stimulus array procedures. Researchers have also tested many variables to determine their potential impact…

  7. Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application. Phase 1 summary report: Shear web design development

    NASA Technical Reports Server (NTRS)

    Laakso, J. H.; Zimmerman, D. K.

    1972-01-01

    An advanced composite shear web design concept was developed for the Space Shuttle orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad + or - 45 deg boron/epoxy web plate with vertical boron/epoxy reinforced aluminum stiffeners. The boron-epoxy laminate contributes to the strength and stiffness efficiency of the basic web section. The titanium-cladding functions to protect the polymeric laminate parts from damaging environments and is chem-milled to provide reinforcement in selected areas. Detailed design drawings are presented for both boron/epoxy reinforced and all-metal shear webs. The weight saving offered is 24% relative to all-metal construction at an attractive cost per pound of weight saved, based on the detailed designs. Small scale element tests substantiate the boron/epoxy reinforced design details in critical areas. The results show that the titanium-cladding reliably reinforces the web laminate in critical edge load transfer and stiffener fastener hole areas.

  8. Modeling root reinforcement using a root-failure Weibull survival function

    NASA Astrophysics Data System (ADS)

    Schwarz, M.; Giadrossich, F.; Cohen, D.

    2013-11-01

    Root networks contribute to slope stability through complex interactions with soil that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamics of root turnover, the quantification of root reinforcement on steep slopes is challenging and consequently the calculation of slope stability also. Although considerable progress has been made, some important aspects of root mechanics remain neglected. In this study we address specifically the role of root-strength variability on the mechanical behavior of a root bundle. Many factors contribute to the variability of root mechanical properties even within a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw). The results show that, for both laboratory and field data sets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the equations of the tensile force, the elasticity of the roots, and the root distribution are the most important steps. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root reinforcement for tensile

  9. Design and realization a skiff racing boat hull made of natural fibers reinforced composite

    NASA Astrophysics Data System (ADS)

    Collotta, M.; Solazzi, L.; Pandini, S.; Tomasoni, G.; Alberti, M.; Donzella, G.

    2016-05-01

    This paper discusses the development of a racing boat with an hull made of a composite material reinforced by natural fibers. In particular, we report here the design and realization of the boat hull, the assessment of its mechanical performance by means of a computer assisted simulation, and the cost analysis to assess the economic sustainability of the new composite developed. The results have shown that the new composite has a performance comparable with conventional glass fiber reinforced composites employed for the realization of this type of boat, accordingly to the technology employed and the lamination sequence adopted. Moreover, the FEM analysis performed over the skiff of the designed and constructed boat has demonstrated a successful choice of the material for real application, as it was later confirmed by the good performance of the boat in water. Finally, the cost analysis highlighted the economic sustainability of the new composite, allowing a cost saving of over 28% with respect to carbon fiber composites.

  10. Analysis and design of on-grade reinforced concrete track support structures

    NASA Technical Reports Server (NTRS)

    Mclean, F. G.; Williams, R. D.; Greening, L. R.

    1972-01-01

    For the improvement of rail service, the Department of Transportation, Federal Rail Administration, is sponsoring a test track on the Atchison, Topeka, and Santa Fe Railway. The test track will contain nine separate rail support structures, including one conventional section for control and three reinforced concrete structures on grade, one slab and two beam sections. The analysis and design of these latter structures was accomplished by means of the finite element method, NASTRAN, and is presented.

  11. Computer-Aided Construction at Designing Reinforced Concrete Columns as Per Ec

    NASA Astrophysics Data System (ADS)

    Zielińska, M.; Grębowski, K.

    2015-02-01

    The article presents the authors' computer program for designing and dimensioning columns in reinforced concrete structures taking into account phenomena affecting their behaviour and information referring to design as per EC. The computer program was developed with the use of C++ programming language. The program guides the user through particular dimensioning stages: from introducing basic data such as dimensions, concrete class, reinforcing steel class and forces affecting the column, through calculating the creep coefficient taking into account the impact of imperfection depending on the support scheme and also the number of mating members at load shit, buckling length, to generating the interaction curve graph. The final result of calculations provides two dependence points calculated as per methods of nominal stiffness and nominal curvature. The location of those points relative to the limit curve determines whether the column load capacity is assured or has been exceeded. The content of the study describes in detail the operation of the computer program and the methodology and phenomena which are indispensable at designing axially and eccentrically the compressed members of reinforced concrete structures as per the European standards.

  12. Free vibration of functionally graded carbon-nanotube-reinforced composite plates with cutout

    PubMed Central

    Mirzaei, Mostafa

    2016-01-01

    Summary During the past five years, it has been shown that carbon nanotubes act as an exceptional reinforcement for composites. For this reason, a large number of investigations have been devoted to analysis of fundamental, structural behavior of solid structures made of carbon-nanotube-reinforced composites (CNTRC). The present research, as an extension of the available works on the vibration analysis of CNTRC structures, examines the free vibration characteristics of plates containing a cutout that are reinforced with uniform or nonuniform distribution of carbon nanotubes. The first-order shear deformation plate theory is used to estimate the kinematics of the plate. The solution method is based on the Ritz method with Chebyshev basis polynomials. Such a solution method is suitable for arbitrary in-plane and out-of-plane boundary conditions of the plate. It is shown that through a functionally graded distribution of carbon nanotubes across the thickness of the plate, the fundamental frequency of a rectangular plate with or without a cutout may be enhanced. Furthermore, the frequencies are highly dependent on the volume fraction of carbon nanotubes and may be increased upon using more carbon nanotubes as reinforcement. PMID:27335742

  13. Free vibration of functionally graded carbon-nanotube-reinforced composite plates with cutout.

    PubMed

    Mirzaei, Mostafa; Kiani, Yaser

    2016-01-01

    During the past five years, it has been shown that carbon nanotubes act as an exceptional reinforcement for composites. For this reason, a large number of investigations have been devoted to analysis of fundamental, structural behavior of solid structures made of carbon-nanotube-reinforced composites (CNTRC). The present research, as an extension of the available works on the vibration analysis of CNTRC structures, examines the free vibration characteristics of plates containing a cutout that are reinforced with uniform or nonuniform distribution of carbon nanotubes. The first-order shear deformation plate theory is used to estimate the kinematics of the plate. The solution method is based on the Ritz method with Chebyshev basis polynomials. Such a solution method is suitable for arbitrary in-plane and out-of-plane boundary conditions of the plate. It is shown that through a functionally graded distribution of carbon nanotubes across the thickness of the plate, the fundamental frequency of a rectangular plate with or without a cutout may be enhanced. Furthermore, the frequencies are highly dependent on the volume fraction of carbon nanotubes and may be increased upon using more carbon nanotubes as reinforcement. PMID:27335742

  14. Key pecking during extinction after intermittent or continuous reinforcement as a function of the number of reinforcers delivered during training.

    PubMed Central

    Zarcone, T J; Branch, M N; Hughes, C E; Pennypacker, H S

    1997-01-01

    Key pecking by 7 pigeons was established and maintained on a multiple variable-ratio variable-ratio (VR) schedule of food presentation. The schedule in one of the components was then changed to fixed-ratio (FR) 1 for a predetermined number of reinforcers. Both components were then changed to extinction (i.e., multiple extinction, extinction). This sequence was repeated a different number of times for each pigeon to determine the relation between the number of reinforcers delivered during each component of the multiple VR FR 1 schedule and the number of responses during extinction. For most pigeons, there were fewer responses during extinction in the presence of a stimulus recently correlated with FR 1, regardless of the number of reinforcers received. The ratio of the total responses in extinction in the former VR component to the total responses in the former FR 1 component increased as the number of reinforcers delivered during each component of the multiple schedule increased. Within-subject replications of the partial-reinforcement extinction effect generally occurred, and there were no overall reductions in the number of responses in extinction with repeated exposures to extinction. PMID:9037782

  15. SOCIAL DOMINANCE IN FEMALE MONKEYS: DOPAMINE RECEPTOR FUNCTION AND COCAINE REINFORCEMENT

    PubMed Central

    Nader, Michael A.; Nader, Susan H.; Czoty, Paul W.; Riddick, Natallia V.; Gage, H. Donald; Gould, Robert W.; Blaylock, Brandi L.; Kaplan, Jay R.; Garg, Pradeep K.; Davies, Huw ML; Morton, Daniel; Garg, Sudha; Reboussin, Beth A.

    2012-01-01

    Background Brain imaging and behavioral studies suggest an inverse relationship between dopamine (DA) D2/D3 receptors and vulnerability to cocaine abuse, though most research has utilized males. For example, male monkeys that become dominant in a social group have significant elevations in D2/D3 receptor availability and are less vulnerable to cocaine reinforcement. Methods DA D2/D3 receptor availability was assessed in female cynomolgus monkeys (n=16) using positron emission tomography (PET) while they were individually housed, 3 months after stable social hierarchies had formed and again when individually housed. In addition, PET was used to examine changes in DA transporter (DAT) availability following social hierarchy formation. After imaging studies were complete, monkeys were implanted with indwelling intravenous catheters and self-administered cocaine (0.001–0.1 mg/kg/injection) under a fixed-ratio 30 schedule of reinforcement. Acquisition of cocaine reinforcement occurred when response rates were significantly higher than when saline was self-administered. Results Neither DAT nor D2/D3 receptor availability in the caudate nucleus and putamen was predictive of social rank, but both significantly changed following formation of social hierarchies. D2/D3 receptor availability significantly increased in females that became dominant, while DAT availability decreased in subordinate females. Dominant female monkeys acquired cocaine reinforcement at significantly lower doses than subordinate monkeys. Conclusions Based on these findings, the relationship between D2/D3 receptor availability and vulnerability to cocaine reinforcement appears opposite in females and males. These data indicate that the social environment profoundly affects the DA system, but does so in ways that have different functional consequences for females than males. PMID:22503110

  16. Tungsten-fiber-reinforced superalloy composite, high-temperature component design considerations

    NASA Technical Reports Server (NTRS)

    Winsa, E. A.

    1983-01-01

    Tungsten fiber reinforced superalloy composites (TFRS) are intended for use in high temperature turbine components. Current turbine component design methodology is based on applying the experience, sometimes semiempirical, gained from over 30 years of superalloy component design. Current composite component design capability is generally limited to the methodology for low temperature resin matrix composites. Often the tendency is to treat TFRS as just another superalloy or low temperature composite. However, TFRS behavior is significantly different than that of superalloys, and the high environment adds consideration not common in low temperature composite component design. The methodology used for preliminary design of TFRS components are described. Considerations unique to TFRS are emphasized. Previously announced in STAR as N82-21259

  17. Design of Fiber Reinforced Foam Sandwich Panels for Large Ares V Structural Applications

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M.; Hopkins, Dale A.

    2010-01-01

    The preliminary design of three major structural components within NASA's Ares V heavy lift vehicle using a novel fiber reinforced foam composite sandwich panel concept is presented. The Ares V payload shroud, interstage, and core intertank are designed for minimum mass using this panel concept, which consists of integral composite webs separated by structural foam between two composite facesheets. The HyperSizer structural sizing software, in conjunction with NASTRAN finite element analyses, is used. However, since HyperSizer does not currently include a panel concept for fiber reinforced foam, the sizing was performed using two separate approaches. In the first, the panel core is treated as an effective (homogenized) material, whose properties are provided by the vendor. In the second approach, the panel is treated as a blade stiffened sandwich panel, with the mass of the foam added after completion of the panel sizing. Details of the sizing for each of the three Ares V components are given, and it is demonstrated that the two panel sizing approaches are in reasonable agreement for thinner panel designs, but as the panel thickness increases, the blade stiffened sandwich panel approach yields heavier panel designs. This is due to the effects of local buckling, which are not considered in the effective core property approach.

  18. Development of design data for graphite reinforced epoxy and polyimide composites

    NASA Technical Reports Server (NTRS)

    Scheck, W. G.

    1974-01-01

    Processing techniques and design data were characterized for a graphite/epoxy composite system that is useful from 75 K to 450 K, and a graphite/polyimide composite system that is useful from 75 K to 589 K. The Monsanto 710 polyimide resin was selected as the resin to be characterized and used with the graphite fiber reinforcement. Material was purchased using the prepreg specification for the design data generation for both the HT-S/710 and HM-S/710 graphite/polyimide composite system. Lamina and laminate properties were determined at 75 K, 297 K, and 589 K. The test results obtained on the skin-stringer components proved that graphite/polyimide composites can be reliably designed and analyzed much like graphite/epoxy composites. The design data generated in the program includes the standard static mechanical properties, biaxial strain data, creep, fatigue, aging, and thick laminate data.

  19. Forced vibration analysis of functionally graded carbon nanotube-reinforced composite plates using a numerical strategy

    NASA Astrophysics Data System (ADS)

    Ansari, R.; Hasrati, E.; Faghih Shojaei, M.; Gholami, R.; Shahabodini, A.

    2015-05-01

    In this paper, the nonlinear forced vibration behavior of composite plates reinforced by carbon nanotubes is investigated by a numerical approach. The reinforcement is considered to be functionally graded (FG) in the thickness direction according to a micromechanical model. The first-order shear deformation theory and von Kármán-type kinematic relations are employed. The governing equations and the corresponding boundary conditions are derived with the use of Hamilton's principle. The generalized differential quadrature (GDQ) method is utilized to achieve a discretized set of nonlinear governing equations. A Galerkin-based scheme is then applied to obtain a time-varying set of ordinary differential equations of Duffing-type. Subsequently, a time periodic discretization is done and the frequency response of plates is determined via the pseudo-arc length continuation method. Selected numerical results are given for the effects of different parameters on the nonlinear forced vibration characteristics of uniformly distributed carbon nanotube- and FG carbon nanotube-reinforced composite plates. It is found that with the increase of CNT volume fraction, the flexural stiffness of plate increases; and hence its natural frequency gets larger. Moreover, it is observed that the distribution type of CNTs significantly affects the vibrational behavior of plate. The results also show that when the mid-plane of plate is CNT-rich, the natural frequency takes its minimum value and the hardening-type response of plate is intensified.

  20. Experimental versus design correlations in multi-cellular fiber reinforced plastic panels

    SciTech Connect

    GangaRao, H.V.S.; Lopez-Anido, R.; Sotiropoulos, S.; Sonti, S.S.; Winegardner, T.

    1996-11-01

    Reinforced plastic (RP) multi-cellular panels have been used recently in designing low-rise buildings. These RP panels were 24 in. wide and 5{1/2} in. thick and were manufactured by pultrusion process using an existing die with a modified (bidirectional) fiber architecture. Constituent materials were rovings, mats, and bi-directional fabrics made of E-glass, and polyester resin. Bending tests were conducted to characterize the stiffness performance of the RP panels and the stiffness results were compared with a simple analytical model. The joining of panels to create a modular deck or wall system is briefly discussed.

  1. Efficient Design and Analysis of Lightweight Reinforced Core Sandwich and PRSEUS Structures

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Yarrington, Phillip W.; Lucking, Ryan C.; Collier, Craig S.; Ainsworth, James J.; Toubia, Elias A.

    2012-01-01

    Design, analysis, and sizing methods for two novel structural panel concepts have been developed and incorporated into the HyperSizer Structural Sizing Software. Reinforced Core Sandwich (RCS) panels consist of a foam core with reinforcing composite webs connecting composite facesheets. Boeing s Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) panels use a pultruded unidirectional composite rod to provide axial stiffness along with integrated transverse frames and stitching. Both of these structural concepts are ovencured and have shown great promise applications in lightweight structures, but have suffered from the lack of efficient sizing capabilities similar to those that exist for honeycomb sandwich, foam sandwich, hat stiffened, and other, more traditional concepts. Now, with accurate design methods for RCS and PRSEUS panels available in HyperSizer, these concepts can be traded and used in designs as is done with the more traditional structural concepts. The methods developed to enable sizing of RCS and PRSEUS are outlined, as are results showing the validity and utility of the methods. Applications include several large NASA heavy lift launch vehicle structures.

  2. Design and Mechanical Evaluation of a Novel Fiber-Reinforced Scaffold for Meniscus Replacement

    PubMed Central

    Balint, Eric; Gatt, Charles J.; Dunn, Michael G.

    2011-01-01

    A fiber-reinforced degradable scaffold for replacement of meniscal tissue was designed, fabricated, and mechanically evaluated. The hypotheses were that 1) the fiber network design would share a portion of compressive loads via the generation of circumferential tensile loads, and 2) the scaffold tensile properties would be similar to those of the meniscus. Two meniscus scaffold designs varying in fiber content (1,000 or 500 fibers: MS1000, MS500) underwent cyclic compressive loading up to 100N and 250N, with resultant tensile loads measured at the anterior and posterior anchors. Standard tensile testing was also performed on each device and ovine menisci. Both scaffolds generated tensile loads directly proportional to the applied compressive loads, with MS1000 scaffolds generating approximately twice the tensile loads of MS500 scaffolds. The tensile strength of MS1000 scaffolds was significantly higher than that of the medial and lateral ovine menisci, and approximately twice that of the MS500 scaffolds. The stiffness of MS1000 scaffolds was lower than that of the lateral meniscus, but not statistically different from that of the medial meniscus. These results support our hypotheses that this novel fiber-reinforced scaffold can mimic the tensile and hoop stress behavior of normal meniscal tissue under compressive loading. The circumferential tensile strength and stiffness are appropriate for a meniscus replacement device. PMID:22021218

  3. Micromechanics and Structural Response of Functionally Graded, Particulate-Matrix, Fiber-Reinforced Composites

    PubMed Central

    Genin, Guy M.; Birman, Victor

    2009-01-01

    Reinforcement of fibrous composites by stiff particles embedded in the matrix offers the potential for simple, economical functional grading, enhanced response to mechanical loads, and improved functioning at high temperatures. Here, we consider laminated plates made of such a material, with spherical reinforcement tailored by layer. The moduli for this material lie within relatively narrow bounds. Two separate moduli estimates are considered: a “two-step” approach in which fibers are embedded in a homogenized particulate matrix, and the Kanaun-Jeulin (2001) approach, which we re-derive in a simple way using the Benveniste (1988) method. Optimal tailoring of a plate is explored, and functional grading is shown to improve the performance of the structures considered. In the example of a square, simply supported, cross-ply laminated panel subjected to uniform transverse pressure, a modest functional grading offers significant improvement in performance. A second example suggests superior blast resistance of the panel achieved at the expense of only a small increase in weight. PMID:23874001

  4. Design principles for riboswitch function.

    PubMed

    Beisel, Chase L; Smolke, Christina D

    2009-04-01

    Scientific and technological advances that enable the tuning of integrated regulatory components to match network and system requirements are critical to reliably control the function of biological systems. RNA provides a promising building block for the construction of tunable regulatory components based on its rich regulatory capacity and our current understanding of the sequence-function relationship. One prominent example of RNA-based regulatory components is riboswitches, genetic elements that mediate ligand control of gene expression through diverse regulatory mechanisms. While characterization of natural and synthetic riboswitches has revealed that riboswitch function can be modulated through sequence alteration, no quantitative frameworks exist to investigate or guide riboswitch tuning. Here, we combined mathematical modeling and experimental approaches to investigate the relationship between riboswitch function and performance. Model results demonstrated that the competition between reversible and irreversible rate constants dictates performance for different regulatory mechanisms. We also found that practical system restrictions, such as an upper limit on ligand concentration, can significantly alter the requirements for riboswitch performance, necessitating alternative tuning strategies. Previous experimental data for natural and synthetic riboswitches as well as experiments conducted in this work support model predictions. From our results, we developed a set of general design principles for synthetic riboswitches. Our results also provide a foundation from which to investigate how natural riboswitches are tuned to meet systems-level regulatory demands. PMID:19381267

  5. Node-Wise Topological Shape Optimum Design for Structural Reinforced Modeling of Michell-Type Concrete Deep Beams

    NASA Astrophysics Data System (ADS)

    Lee, Dongkyu; Park, Sungsoo; Shin, Soomi

    This study presents an associated structural design to continuous material topology optimization and a particular case of shape optimization using node-wise densities as design parameters. The generation of optimal shapes and topologies represented in this study is based on a three-dimensional density function bilinearly interpolated by element shape functions and nodal densities. The material interface between void and solid regions is described by a specific 0.5 cut-off level of continuous and smooth iso-lines of the nodal density function on a fixed mesh. This approach allows us to perform a simultaneous node-wise topology and shape optimization, which can be easily implemented by existing gradient-based optimization codes. Contrary to those of conventional material topology optimization methods, these optimal solutions are similar to ideal optimal solutions from analytical optimization techniques. Numerical examples for structural reinforced modeling of Michell-type concrete deep beams are used to demonstrate the efficiency and superiority of the resolutions of the present method.

  6. German guidelines for steel fiber reinforced shotcrete in tunnels with special consideration of design and statical aspects

    SciTech Connect

    Schmidt-Schleicher, H.

    1995-12-31

    Steel fiber reinforced concrete can undoubtedly absorb tensile forces. The utilization of this characteristic for the design and specifications of support structures for underground tunnels is regulated by the new Guidelines from the German Concrete Association. Recommendations are given in these guidelines for construction design and for construction itself. The required tests for classification, suitability and quality monitoring are presented.

  7. Functional communication training using assistive devices: recruiting natural communities of reinforcement.

    PubMed Central

    Durand, V M

    1999-01-01

    We evaluated the effectiveness of functional communication training (FCT) as an intervention for the problem behavior exhibited by 5 students with severe disabilities both in school and in the community. Following an assessment of the function of their problem behavior, the students were taught to use assistive communication devices in school to request the objects and activities that presumably were maintaining their behavior. Multiple baseline data collected across the students indicated that not only did the students use their devices successfully, but the intervention also reduced their problem behavior. In addition, data from community settings showed generalization to untrained community members. These results replicate other successful efforts to use FCT with individuals having limited communication skills, and demonstrate the value of teaching skills to recruit natural communities of reinforcement in order to generalize intervention effects to meaningful nontraining environments. PMID:10513023

  8. Optimal design of variable-stiffness fiber-reinforced composites using cellular automata

    NASA Astrophysics Data System (ADS)

    Setoodeh, Shahriar

    The growing number of applications of composite materials in aerospace and naval structures along with advancements in manufacturing technologies demand continuous innovations in the design of composite structures. In the traditional design of composite laminates, fiber orientation angles are constant for each layer and are usually limited to 0, 90, and +/-45 degrees. To fully benefit from the directional properties of composite laminates, such limitations have to be removed. The concept of variable-stiffness laminates allows the stiffness properties to vary spatially over the laminate. Through tailoring of fiber orientations and laminate thickness spatially in an optimal fashion, mechanical properties of a part can be improved. In this thesis, the optimal design of variable-stiffness fiber-reinforced composite laminates is studied using an emerging numerical engineering optimization scheme based on the cellular automata paradigm. A cellular automaton (CA) based design scheme uses local update rule for both field variables (displacements) and design variables (lay-up configuration and laminate density measure) in an iterative fashion to convergence to an optimal design. In the present work, the displacements are updated based on the principle of local equilibrium and the design variables are updated according to the optimality criteria for minimum compliance design. A closed form displacement update rule for constant thickness isotropic continua is derived, while for the general anisotropic continua with variable thickness a numeric update rule is used. Combined lay-up and topology design of variable-stiffness flat laminates is performed under the action of in-plane loads and bending loads. An optimality criteria based formulation is used to obtain local design rules for minimum compliance design subject to a volume constraint. It is shown that the design rule splits into a two step application. In the first step an optimal lay-up configuration is computed and in

  9. Reinforcer magnitude and resistance to disruption of forgetting functions and response rates.

    PubMed

    Berry, Meredith S; Odum, Amy L

    2014-05-01

    The present experiment investigated the effects of reinforcer magnitude on resistance to disruption of remembering and response rates. Pigeons were exposed to a variable-interval (VI), delayed-matching-to-sample (DMTS) procedure with two components (rich and lean, distinguished by differing discriminative stimuli and hopper presentation duration). Completion of a VI 20 s schedule resulted in DMTS trials. In a DMTS trial, a choice of one of two comparison stimuli resulted in food if the choice matched the color of the previously presented sample stimulus. Separable aspects of the forgetting functions (initial discrimination and rate of forgetting) were examined by determining accuracy across a range of delays. Response rates and accuracy were higher in the rich relative to the lean component during baseline, and were more persistent during disruptors (extinction and prefeeding). During DMTS trials, extinction decreased initial discrimination more in the lean than the rich component, but had no systematic effect on rate of forgetting. During prefeeding, the rate of forgetting increased more in the lean than the rich component, but initial discrimination was not systematically affected. These results show persistence of response rates and remembering are positively related to reinforcer magnitude. The type of disruptor also influences the way in which remembering is disrupted. PMID:24723340

  10. Arctigenin from Fructus Arctii (Seed of Burdock) Reinforces Intestinal Barrier Function in Caco-2 Cell Monolayers.

    PubMed

    Shin, Hee Soon; Jung, Sun Young; Back, Su Yeon; Do, Jeong-Ryong; Shon, Dong-Hwa

    2015-01-01

    Fructus Arctii is used as a traditional herbal medicine to treat inflammatory diseases in oriental countries. This study aimed to investigate effect of F. Arctii extract on intestinal barrier function in human intestinal epithelial Caco-2 cells and to reveal the active component of F. Arctii. We measured transepithelial electrical resistance (TEER) value (as an index of barrier function) and ovalbumin (OVA) permeation (as an index of permeability) to observe the changes of intestinal barrier function. The treatment of F. Arctii increased TEER value and decreased OVA influx on Caco-2 cell monolayers. Furthermore, we found that arctigenin as an active component of F. Arctii increased TEER value and reduced permeability of OVA from apical to the basolateral side but not arctiin. In the present study, we revealed that F. Arctii could enhance intestinal barrier function, and its active component was an arctigenin on the functionality. We expect that the arctigenin from F. Arctii could contribute to prevention of inflammatory, allergic, and infectious diseases by reinforcing intestinal barrier function. PMID:26550018

  11. Arctigenin from Fructus Arctii (Seed of Burdock) Reinforces Intestinal Barrier Function in Caco-2 Cell Monolayers

    PubMed Central

    Shin, Hee Soon; Jung, Sun Young; Back, Su Yeon; Do, Jeong-Ryong; Shon, Dong-Hwa

    2015-01-01

    Fructus Arctii is used as a traditional herbal medicine to treat inflammatory diseases in oriental countries. This study aimed to investigate effect of F. Arctii extract on intestinal barrier function in human intestinal epithelial Caco-2 cells and to reveal the active component of F. Arctii. We measured transepithelial electrical resistance (TEER) value (as an index of barrier function) and ovalbumin (OVA) permeation (as an index of permeability) to observe the changes of intestinal barrier function. The treatment of F. Arctii increased TEER value and decreased OVA influx on Caco-2 cell monolayers. Furthermore, we found that arctigenin as an active component of F. Arctii increased TEER value and reduced permeability of OVA from apical to the basolateral side but not arctiin. In the present study, we revealed that F. Arctii could enhance intestinal barrier function, and its active component was an arctigenin on the functionality. We expect that the arctigenin from F. Arctii could contribute to prevention of inflammatory, allergic, and infectious diseases by reinforcing intestinal barrier function. PMID:26550018

  12. Design and performance of a shape memory alloy-reinforced composite aerodynamic profile

    NASA Astrophysics Data System (ADS)

    Simpson, J. C.; Boller, C.

    2008-04-01

    Based on a shape memory alloy (SMA)-reinforced composite developed separately, the applicability of the composite has been demonstrated through realization of a realistically scaled aerodynamic profile of around 0.5 m span by 0.5 m root chord whose skins had been made from this composite. The design, manufacturing and assembly of the profile are described. The curved skins were manufactured with two layers of SMA wires integrated into the layup of aramid fibre prepregs. All SMA wires were connected such that they can be operated as individual sets of wires and at low voltages, similar to the conditions for electrical energy generation in a real aircraft. The profile was then mounted on a vibration test rig and excited by a shaker at its tip which allowed the dynamic performance of the profile to be validated under internal actuation conditions generated through the SMA wires.

  13. Functional Communication Training and Chained Schedules of Reinforcement to Treat Challenging Behavior Maintained by Terminations of Activity Interruptions

    ERIC Educational Resources Information Center

    Falcomata, Terry S.; Roane, Henry S.; Muething, Colin S.; Stephenson, Kasey M.; Ing, Anna D.

    2012-01-01

    In this article, the authors evaluated functional communication training (FCT) and a chained schedule of reinforcement for the treatment of challenging behavior exhibited by two individuals diagnosed with Asperger syndrome and autism, respectively. Following a functional analysis with undifferentiated results, the authors demonstrated that…

  14. Creating a Reinforcement Learning Controller for Functional Electrical Stimulation of a Human Arm.

    PubMed

    Thomas, Philip S; Branicky, Michael; van den Bogert, Antonie; Jagodnik, Kathleen

    2008-01-01

    Clinical tests have shown that the dynamics of a human arm, controlled using Functional Electrical Stimulation (FES), can vary significantly between and during trials. In this paper, we study the application of Reinforcement Learning to create a controller that can adapt to these changing dynamics of a human arm. Development and tests were done in simulation using a two-dimensional arm model and Hill-based muscle dynamics. An actor-critic architecture is used with artificial neural networks for both the actor and the critic. We begin by training it using a Proportional Derivative (PD) controller as a supervisor. We then make clinically relevant changes to the dynamics of the arm and test the actor-critic's ability to adapt without supervision in a reasonable number of episodes. PMID:22081795

  15. Synthesis and Characterization of Carbon Nanotubes for Reinforced and Functional Applications

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C.-H.; Lehoczky, S.; Watson, M.

    2003-01-01

    Many efforts have been engaged recently in synthesizing single-walled and multi-walled carbon nanotubes due to their superior mechanical, electrical and thermal properties, which could be used for numerous applications to enhance the performance of electronics, sensors and composites. This presentation will demonstrate the synthesizing process of carbon nanotube by thermal chemical vapor deposition and the characterization results by using electron microscopy and optical spectroscopy. Carbon nanotubes could be synthesized on various substances. The conditions of fabricating single-walled or multi-walled carbon nanotubes depend strongly on temperature and hydrocarbon concentration but weakly on pressure. The sizes, orientations, and growth modes of carbon nanotubes will be illustrated. The advantages and limitations of several potential aerospace applications such as reinforced and functional composites, temperature sensing, and thermal control by using carbon nanotubes will be discussed.

  16. Transverse Reinforcement in Reinforced Concrete Columns

    NASA Astrophysics Data System (ADS)

    Gramblička, Štefan; Veróny, Peter

    2013-11-01

    In the article we are dealing with the influence of transverse reinforcement to the resistance of a cross-section of the reinforced concrete columns and also with the effective detailing of the column reinforcement. We are verifying the correctness of design guides for detailing of transverse reinforcement. We are also taking into account the diameter of stirrups and its influence over transverse deformation of column.

  17. Design issues for a reinforcement-based self-learning fuzzy controller

    NASA Technical Reports Server (NTRS)

    Yen, John; Wang, Haojin; Dauherity, Walter

    1993-01-01

    Fuzzy logic controllers have some often cited advantages over conventional techniques such as PID control: easy implementation, its accommodation to natural language, the ability to cover wider range of operating conditions and others. One major obstacle that hinders its broader application is the lack of a systematic way to develop and modify its rules and as result the creation and modification of fuzzy rules often depends on try-error or pure experimentation. One of the proposed approaches to address this issue is self-learning fuzzy logic controllers (SFLC) that use reinforcement learning techniques to learn the desirability of states and to adjust the consequent part of fuzzy control rules accordingly. Due to the different dynamics of the controlled processes, the performance of self-learning fuzzy controller is highly contingent on the design. The design issue has not received sufficient attention. The issues related to the design of a SFLC for the application to chemical process are discussed and its performance is compared with that of PID and self-tuning fuzzy logic controller.

  18. Design issues of a reinforcement-based self-learning fuzzy controller for petrochemical process control

    NASA Technical Reports Server (NTRS)

    Yen, John; Wang, Haojin; Daugherity, Walter C.

    1992-01-01

    Fuzzy logic controllers have some often-cited advantages over conventional techniques such as PID control, including easier implementation, accommodation to natural language, and the ability to cover a wider range of operating conditions. One major obstacle that hinders the broader application of fuzzy logic controllers is the lack of a systematic way to develop and modify their rules; as a result the creation and modification of fuzzy rules often depends on trial and error or pure experimentation. One of the proposed approaches to address this issue is a self-learning fuzzy logic controller (SFLC) that uses reinforcement learning techniques to learn the desirability of states and to adjust the consequent part of its fuzzy control rules accordingly. Due to the different dynamics of the controlled processes, the performance of a self-learning fuzzy controller is highly contingent on its design. The design issue has not received sufficient attention. The issues related to the design of a SFLC for application to a petrochemical process are discussed, and its performance is compared with that of a PID and a self-tuning fuzzy logic controller.

  19. A composite-appropriate integration method of thick functional components in fibre-reinforced plastics

    NASA Astrophysics Data System (ADS)

    Filippatos, A.; Höhne, R.; Kliem, M.; Gude, M.

    2016-03-01

    The use of integrated structural health monitoring systems for critical composite parts, such as wind turbine blades, fuselage and wing parts, is an promising approach to guarantee a safe and efficient operational lifetime of such components. Therefore, the integration of thick functional components like sensors, actuators and electronic components is often necessary. An optimal integration of such components should be ensured without material imperfections in the composite structure, i.e. voids and resin rich areas, and failure of the functional components. In this paper, first investigations were undertaken for a basic understanding of the mechanical performance of a fibre reinforced plastic component with integrated functional elements. The influence of different materials and treatment methods for the encapsulation of electronic components was experimentally investigated under static and dynamic loading tests. By means of a parametric finite element model, the effects of an encapsulation and various parameters such as the shape and orientation of the electronic components were examined. Several encapsulation variants were investigated in order to minimise the chance of failure initiations. Based both on experimental and numerical results, a preferred composite integration concept was selected for an electronic board and some first recommendations for an optimal integration were derived.

  20. Teacher Implementation of Trial-Based Functional Analysis and Differential Reinforcement of Alternative Behavior for Students with Challenging Behavior

    ERIC Educational Resources Information Center

    Flynn, Susan D.; Lo, Ya-yu

    2016-01-01

    The purpose of this study was to examine the effects of a training package on three middle school special education teachers' accurate implementation of trial-based functional analysis (TBFA) and differential reinforcement of alternative behavior (DRA) with their students with autism spectrum disorders or emotional and behavioral disorders in the…

  1. Assessing Preferences for Positive and Negative Reinforcement during Treatment of Destructive Behavior with Functional Communication Training

    ERIC Educational Resources Information Center

    Fisher, Wayne W.; Adelinis, John D.; Volkert, Valerie M.; Keeney, Kris M.; Neidert, Pamela L.; Hovanetz, Alyson

    2005-01-01

    Results of prior studies (e.g. [J. Appl. Behav. Anal. 32 (1999) 285]) showing that participants chose alternative behavior (compliance) over escape-reinforced destructive behavior when this latter response produced escape and the former response produced positive reinforcement may have been due to (a) the value of the positive reinforcer…

  2. A Function-Based Classroom Behavior Intervention Using Non-Contingent Reinforcement Plus Response Cost

    ERIC Educational Resources Information Center

    Nolan, Julene D.; Filter, Kevin J.

    2012-01-01

    This study investigated the use of noncontingent reinforcement with response cost to reduce problem verbal and physical behavior maintained by automatic reinforcement in an internationally adopted, post-institutionalized student diagnosed with ADHD. Systematic direct observation was employed to measure behavior in a single-subject withdrawal…

  3. Design and evaluation of a bolted joint for a discrete carbon-epoxy rod-reinforced hat section

    NASA Technical Reports Server (NTRS)

    Rousseau, Carl Q.; Baker, Donald J.

    1996-01-01

    The use of prefabricated pultruded carbon-epoxy rods has reduced the manufacturing complexity and costs of stiffened composite panels while increasing the damage tolerance of the panels. However, repairability of these highly efficient discrete stiffeners has been a concern. Design, analysis, and test results are presented in this paper for a bolted-joint repair for the pultruded rod concept that is capable of efficiently transferring axial loads in a hat-section stiffener on the upper skin segment of a heavily loaded aircraft wing component. A tension and a compression joint design were evaluated. The tension joint design achieved approximately 1.0% strain in the carbon-epoxy rod-reinforced hat-section and failed in a metal fitting at 166% of the design ultimate load. The compression joint design failed in the carbon-epoxy rod-reinforced hat-section test specimen area at approximately 0.7% strain and at 110% of the design ultimate load. This strain level of 0.7% in compression is similar to the failure strain observed in previously reported carbon-epoxy rod-reinforced hat-section column tests.

  4. Design and Evaluation of a Bolted Joint for a Discrete Carbon-Epoxy Rod-Reinforced Hat Section

    NASA Technical Reports Server (NTRS)

    Baker, Donald J.; Rousseau, Carl Q.

    1996-01-01

    The use of pre-fabricated pultruded carbon-epoxy rods has reduced the manufacturing complexity and costs of stiffened composite panels while increasing the damage tolerance of the panels. However, repairability of these highly efficient discrete stiffeners has been a concern. Design, analysis, and test results are presented in this paper for a bolted-joint repair for the pultruded rod concept that is capable of efficiently transferring axial loads in a hat-section stiffener on the upper skin segment of a heavily loaded aircraft wing component. A tension and a compression joint design were evaluated. The tension joint design achieved approximately 1.0 percent strain in the carbon-epoxy rod-reinforced hat-section and failed in a metal fitting at 166 percent of the design ultimate load. The compression joint design failed in the carbon-epoxy rod-reinforced hat-section test specimen area at approximately 0.7 percent strain and at 110 percent of the design ultimate load. This strain level of 0.7 percent in compression is similar to the failure strain observed in previously reported carbon-epoxy rod-reinforced hat-section column tests.

  5. Multifunctional cyanate ester nanocomposites reinforced by hexagonal boron nitride after noncovalent biomimetic functionalization.

    PubMed

    Wu, Hongchao; Kessler, Michael R

    2015-03-18

    Boron nitride (BN) reinforced polymer nanocomposites have attracted a growing research interest in the microelectronic industry for their uniquely thermal conductive but electrical insulating properties. To overcome the challenges in surface functionalization, in this study, hexagonal boron nitride (h-BN) nanoparticles were noncovalently modified with polydopamine in a solvent-free aqueous condition. The strong π-π interaction between the hexagonal structural BN and aromatic dopamine molecules facilitated 15 wt % polydopamine encapsulating the nanoparticles. High-performance bisphenol E cyanate ester (BECy) was incorporated by homogeneously dispersed h-BN at different loadings and functionalities to investigate their effects on thermo-mechanical, dynamic-mechanical, and dielectric properties, as well as thermal conductivity. Different theoretical and empirical models were successfully applied to predict thermal and dielectric properties of h-BN/BECy nanocomposites. Overall, the prepared h-BN/BECy nanocomposites exhibited outstanding performance in dimensional stability, dynamic-mechanical properties, and thermal conductivity, together with the controllable dielectric property and preserved thermal stability for high-temperature applications. PMID:25726956

  6. Electronic Design Automation: Integrating the Design and Manufacturing Functions

    NASA Technical Reports Server (NTRS)

    Bachnak, Rafic; Salkowski, Charles

    1997-01-01

    As the complexity of electronic systems grows, the traditional design practice, a sequential process, is replaced by concurrent design methodologies. A major advantage of concurrent design is that the feedback from software and manufacturing engineers can be easily incorporated into the design. The implementation of concurrent engineering methodologies is greatly facilitated by employing the latest Electronic Design Automation (EDA) tools. These tools offer integrated simulation of the electrical, mechanical, and manufacturing functions and support virtual prototyping, rapid prototyping, and hardware-software co-design. This report presents recommendations for enhancing the electronic design and manufacturing capabilities and procedures at JSC based on a concurrent design methodology that employs EDA tools.

  7. Design of the IXO optics based on thin glass plates connected by reinforcing ribs

    NASA Astrophysics Data System (ADS)

    Parodi, G.; Martelli, F.; Basso, S.; Citterio, O.; Civitani, M.; Conconi, P.; Ghigo, M.; Pareschi, G.; Zambra, A.

    2011-09-01

    Effective area requirements for the large X-ray mirror of the International X-ray Observatory (IXO) are about 3 m2 at 1keV, 0.65 m2 at 6 keV and 150 cm2 at 30 keV. Because of its large dimension, the telescope cannot be realized as a monolithic structure but rather it requires the integration and assembly in the telescope optical bench of a number of basic module units, called X-ray Optical Unit (XOU). We are currently studying a method for the production of these basic units that is based on the slumping technology for the production of thin glass segmented mirrors. It foresees the implementation of a stacking integration concept based on the use of reinforcing ribs connecting the glass segments in order to create very stiff structures. This paper reports on the last design of the single optical module and describe the results of FEM analyses that show how it is possible to use an innovative approach to the integration of the slumped glass foils.

  8. Towards Practical Carbonation Prediction and Modelling for Service Life Design of Reinforced Concrete Structures

    NASA Astrophysics Data System (ADS)

    Ekolu, O. S.

    2015-11-01

    Amongst the scientific community, the interest in durability of concrete structures has been high for quite a long time of over 40 years. Of the various causes of degradation of concrete structures, corrosion is the most widespread durability problem and carbonation is one of the two causes of steel reinforcement corrosion. While much scientific understanding has been gained from the numerous carbonation studies undertaken over the past years, it is still presently not possible to accurately predict carbonation and apply it in design of structures. This underscores the complex nature of the mechanisms as influenced by several interactive factors. Based on critical literature and some experience of the author, it is found that there still exist major challenges in establishing a mathematical constitutive relation for realistic carbonation prediction. While most current models employ permeability /diffusion as the main model property, analysis shows that the most practical material property would be compressive strength, which has a low coefficient of variation of 20% compared to 30 to 50% for permeability. This important characteristic of compressive strength, combined with its merit of simplicity and data availability at all stages of a structure's life, promote its potential use in modelling over permeability. By using compressive strength in carbonation prediction, the need for accelerated testing and permeability measurement can be avoided. This paper attempts to examine the issues associated with carbonation prediction, which could underlie the current lack of a sound established prediction method. Suggestions are then made for possible employment of different or alternative approaches.

  9. Durability of a reinforced concrete designed for the construction of an intermediate-level radioactive waste disposal facility

    NASA Astrophysics Data System (ADS)

    Duffó, G. S.; Arva, E. A.; Schulz, F. M.; Vazquez, D. R.

    2012-01-01

    The National Atomic Energy Commission of the Argentine Republic is developing a nuclear waste disposal management programme that contemplates the design and construction of a facility for the final disposal of intermediate-level radioactive wastes. The repository is based on the use of multiple, independent and redundant barriers. The major components are made in reinforced concrete so, the durability of these structures is an important aspect for the facility integrity. This work presents an investigation performed on a reinforced concrete specifically designed for this purpose, to predict the service life of the intermediate level radioactive waste disposal facility from data obtained with several techniques. Results obtained with corrosion sensors embedded in a concrete prototype are also included. The information obtained will be used for the final design of the facility in order to guarantee a service life more or equal than the foreseen durability for this type of facilities.

  10. Behavior and design of reinforced concrete column-type lapped splices subjected to high-intensity cyclic loading

    NASA Astrophysics Data System (ADS)

    Sivakumar, B.; White, R. N.; Gergely, P.

    1982-10-01

    The behavior and design of lapped splices in reinforced concrete column type specimens under high intensity flexural cyclic loads was studied. Special attention is focused on the transverse steel requirements of specimens with more than two splices in a layer; the use of offsets in spliced bars; the effect of concrete strength on splice strength and behavior; and the strength of epoxy-repaired splices. Procedures are provided for the design of reinforced lapped splices to sustain at least twenty reversing load cycles beyond yield and a maximum rebar strain at the splice of at least 2.5 times the yield strain. The key aspect of the design is the provision of closely spaced uniformly distributed stirrup ties in the splice region. Equations are developed for the spacing of stirrups and the minimum splice length requirement.

  11. Silk microfiber-reinforced silk hydrogel composites for functional cartilage tissue repair

    PubMed Central

    Yodmuang, Supansa; McNamara, Stephanie L.; Nover, Adam B.; Mandal, Biman B.; Agarwal, Monica; Kelly, Terri-Ann N.; Chao, Pen-hsiu Grace; Hung, Clark; Kaplan, David L.; Vunjak-Novakovic, Gordana

    2014-01-01

    Cartilage tissue lacks an intrinsic capacity for self-regeneration due to slow matrix turnover, a limited supply of mature chondrocytes and insufficient vasculature. Although cartilage tissue engineering has achieved some success using agarose as a scaffolding material, major challenges of agarose-based cartilage repair, including non-degradability, poor tissue–scaffold integration and limited processing capability, have prompted the search for an alternative biomaterial. In this study, silk fiber–hydrogel composites (SF–silk hydrogels) made from silk microfibers and silk hydrogels were investigated for their potential use as a support material for engineered cartilage. We demonstrated the use of 100% silk-based fiber–hydrogel composite scaffolds for the development of cartilage constructs with properties comparable to those made with agarose. Cartilage constructs with an equilibrium modulus in the native tissue range were fabricated by mimicking the collagen fiber and proteoglycan composite architecture of native cartilage using biocompatible, biodegradable silk fibroin from Bombyx mori. Excellent chondrocyte response was observed on SF–silk hydrogels, and fiber reinforcement resulted in the development of more mechanically robust constructs after 42 days in culture compared to silk hydrogels alone. Thus, we demonstrate the versatility of silk fibroin as a composite scaffolding material for use in cartilage tissue repair to create functional cartilage constructs that overcome the limitations of agarose biomaterials, and provide a much-needed alternative to the agarose standard. PMID:25281788

  12. Design for a Nine-Month School-Wide Program of Token Reinforcement for the Trainable Mentally Retarded. Research and Development Report, Volume IV, Number 4.

    ERIC Educational Resources Information Center

    Ayllon, T.; Barnes, Jarvis

    Outlined are plans for a 9-month elementary school-wide program of token reinforcement for the trainable mentally retarded (TMR), which is said to allow for later additional components. Program focus is to be application of reinforcement to TMR academic work. All children will take the Metropolitan Readiness Test in pretest and posttest design for…

  13. Two functional serotonin polymorphisms moderate the effect of food reinforcement on BMI

    PubMed Central

    Carr, Katelyn A.; Lin, Henry; Fletcher, Kelly D.; Sucheston, Lara; Singh, Prashant K.; Salis, Robbert; Erbe, Richard; Faith, Myles; Allison, David; Stice, Eric; Epstein, Leonard H.

    2014-01-01

    Food reinforcement, or the motivation to eat, has been associated with increased energy intake, greater body weight and prospective weight gain. Much of the previous research on the reinforcing value of food has focused on the role of dopamine, but it may be worthwhile to examine genetic polymorphisms in the serotonin and opioid systems as these neurotransmitters have been shown to be related to reinforcement processes and to influence energy intake. We examined the relationship among 44 candidate genetic polymorphisms in the dopamine, serotonin and opioid systems, and food reinforcement and body mass index (BMI) in a sample of 245 individuals. Polymorphisms in the Monoamine oxidase A (MAOA-LPR) and serotonin receptor 2A genes (rs6314) moderated the effect of food reinforcement on BMI, accounting for an additional 5-10% variance and revealed a potential role of the single nucleotide polymorphism, rs6314 in the serotonin 2A receptor as a differential susceptibility factor for obesity. Differential susceptibility describes a factor that can confer either risk or protection depending on a second variable, such that rs6314 is predictive of both high and low BMI based on the level of food reinforcement, while the diathesis stress or dual-gain model influences only one end of the outcome measure. The interaction with MAOA-LPR better fit the dual-risk or diathesis stress model, with the 3.5R/4R allele conferring protection for individuals low in food reinforcement. These results provide new insight into genes theoretically involved in obesity and support the hypothesis that genetics moderate the association between food reinforcement on BMI. PMID:23544600

  14. Signaled alternative reinforcement and the persistence of operant behavior.

    PubMed

    Bland, Vikki J; Bai, John Y H; Fullerton, Jane A; Podlesnik, Christopher A

    2016-07-01

    Differential reinforcement of alternative behavior (DRA) is a treatment designed to eliminate problem behavior by reinforcing an alternative behavior at a higher rate. Availability of alternative reinforcement may be signaled, as with Functional Communication Training, or unsignaled. Whether or not alternative reinforcement is signaled could influence both the rate and persistence of problem behavior. The present study investigated whether signaling the availability of alternative reinforcement affects the rate and persistence of a concurrently available target response with pigeons. Three components of a multiple concurrent schedule arranged equal reinforcement rates for target responding. Two of the components also arranged equal reinforcement rates for an alternative response. In one DRA component, a discrete stimulus signaled the availability of response-contingent alternative reinforcement by changing the keylight color upon reinforcement availability. In the other DRA component, availability of alternative reinforcement was not signaled. Target responding was most persistent in the unsignaled DRA component when disrupted by satiation, free food presented between components, and extinction, relative to the signaled DRA and control components. These findings suggest the discrete stimulus functionally separated the availability of alternative reinforcement from the discriminative stimuli governing target responding. These findings provide a novel avenue to explore in translational research assessing whether signaling the availability of alternative reinforcement with DRA treatments reduces the persistence of problem behavior. PMID:27282131

  15. Anchorage reinforcement with a fixed functional appliance during protraction of the mandibular second molars into the first molar extraction sites.

    PubMed

    Chhibber, Aditya; Upadhyay, Madhur

    2015-07-01

    Protraction of posterior teeth into edentulous spaces is a challenge. This report describes the treatment of a 19-year-old woman with missing mandibular first molars owing to caries. A fixed functional appliance was used for anchorage reinforcement during mandibular second molar protraction. Eight millimeters of bilateral protraction was done with bodily mesial movement of the molars and no lingual tipping of the incisors. PMID:26124039

  16. A Preliminary Investigation of the Reinforcement Function of Signal Detections in Simulated Baggage Screening: Further Support for the Vigilance Reinforcement Hypothesis

    ERIC Educational Resources Information Center

    Hogan, Lindsey C.; Bell, Matthew; Olson, Ryan

    2009-01-01

    The vigilance reinforcement hypothesis (VRH) asserts that errors in signal detection tasks are partially explained by operant reinforcement and extinction processes. VRH predictions were tested with a computerized baggage screening task. Our experiment evaluated the effects of signal schedule (extinction vs. variable interval 6 min) and visual…

  17. Design and installation of a cathodic protection system for a large reinforced concrete intake structure in the Arabian Gulf

    SciTech Connect

    Ali, M.; Al-Ghannam, H.

    1997-09-01

    The paper describes the condition survey methodology, design and installation of a cathodic protection (C.P.) system for a large reinforced concrete reservoir and sea water intake structure. The structure is critical for the supply of cooling water for a 2.4 million metric ton steel plant. The C.P. System consisting of mixed metal oxide coating on titanium mesh type anodes and automatic voltage/current controlled rectifiers was successfully installed and has been operating within design guidelines for the past 15 months.

  18. 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.

  19. 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.

  20. Network architecture functional description and design

    SciTech Connect

    Stans, L.; Bencoe, M.; Brown, D.; Kelly, S.; Pierson, L.; Schaldach, C.

    1989-05-25

    This report provides a top level functional description and design for the development and implementation of the central network to support the next generation of SNL, Albuquerque supercomputer in a UNIX{reg sign} environment. It describes the network functions and provides an architecture and topology.

  1. Positive and Negative Reinforcers: How about the Second and Third Functions?

    ERIC Educational Resources Information Center

    Staats, Arthur W.

    2006-01-01

    The author of this article presents his own explanation on the two types of conditioning--respondent and operant. He states that when withdrawal of a negative reinforcer is the contingency that increases the strength of the operant behavior, the stimulus will have a negative emotional response to the experimental chamber. However, when a positive…

  2. Language Learning of Children as a Function of Sensory Mode of Presentation and Reinforcement Procedure.

    ERIC Educational Resources Information Center

    Oyer, Herbert J.; Frankmann, Judith P.

    Programed training filmstrips from Project LIFE (Language Instruction to Facilitate Education) were used with 114 hearing impaired children and 15 normal hearing language impaired children (4- to 13-years old) to assess the effects of auditory supplementation and a token reinforcement program on language learning and to investigate retention and…

  3. Practical method for analysis and design of slender reinforced concrete columns subjected to biaxial bending and axial loads

    NASA Astrophysics Data System (ADS)

    Bouzid, T.; Demagh, K.

    2011-03-01

    Reinforced and concrete-encased composite columns of arbitrarily shaped cross sections subjected to biaxial bending and axial loads are commonly used in many structures. For this purpose, an iterative numerical procedure for the strength analysis and design of short and slender reinforced concrete columns with a square cross section under biaxial bending and an axial load by using an EC2 stress-strain model is presented in this paper. The computational procedure takes into account the nonlinear behavior of the materials (i.e., concrete and reinforcing bars) and includes the second - order effects due to the additional eccentricity of the applied axial load by the Moment Magnification Method. The ability of the proposed method and its formulation has been tested by comparing its results with the experimental ones reported by some authors. This comparison has shown that a good degree of agreement and accuracy between the experimental and theoretical results have been obtained. An average ratio (proposed to test) of 1.06 with a deviation of 9% is achieved.

  4. Biocomposites from Natural Rubber: Synergistic Effects of Functionalized Cellulose Nanocrystals as Both Reinforcing and Cross-Linking Agents via Free-Radical Thiol-ene Chemistry.

    PubMed

    Parambath Kanoth, Bipinbal; Claudino, Mauro; Johansson, Mats; Berglund, Lars A; Zhou, Qi

    2015-08-01

    Natural rubber/cellulose nanocrystals (NR/CNCs) form true biocomposites from renewable resources and are demonstrated to show significantly improved thermo-mechanical properties and reduced stress-softening. The nanocomposites were prepared from chemically functionalized CNCs bearing thiols. CNCs served as both reinforcing and cross-linking agents in the NR matrix, and the study was designed to prove the cross-linking function of modified CNCs. CNCs were prepared from cotton, and the cross-linkable mercapto-groups were introduced onto the surface of CNCs by esterification. Nanocomposite films were prepared by dispersing the modified CNCs (m-CNCs) in NR matrix by solution casting. The cross-links at the filler-matrix (m-CNCs-NR) interface were generated by photochemically initiated thiol-ene reactions as monitored by real-time FTIR analysis. The synergistic effects of reinforcement and chemical cross-linking at the m-CNCs-NR interface on structure, thermo-mechanical, and stress-softening behavior were investigated. Methods included field emission scanning electron microscopy (FE-SEM), swelling tests, dynamic mechanical analysis, and tensile tests. Compared to biocomposites from NR with unmodified CNCs, the NR/m-CNCs nanocomposites showed 2.4-fold increase in tensile strength, 1.6-fold increase in strain-to-failure, and 2.9-fold increase in work-of-fracture at 10 wt % of m-CNCs in NR. PMID:26151647

  5. The role of non-linear deformation analyses in the design of a reinforced soil berm at Red River U-frame lock No. 1

    NASA Astrophysics Data System (ADS)

    Ebeling, Robert M.; Peters, John F.; Mosher, Reed L.

    1997-11-01

    This paper describes a design application of non-linear deformation analysis to a complex soil-structure-foundation interaction problem through use of a finite element analysis. The problem consists of a proposed renovation to an existing soil-founded U-frame lock structure consisting of construction of a densely reinforced soil berm adjacent to an existing lock wall. Major questions facing the designer involve reduction of the earth pressure on the lock wall, layout of the reinforcing in the soil berm, and collateral effects of berm construction on the U-frame lock structure. A non-linear deformation analysis played a central role in addressing all of these questions. Berm construction and four operational load cases were used to understand the performance of the reinforced berm and to discern interactions among the lock, the backfill, the foundation strata of the U-frame lock, the reinforced berm, and the foundation strata of the reinforced berm. Insight gained from the soil-structure-foundation interaction analyses led to an alteration to the proposed reinforcement layout to enhance the performance of the reinforced soil berm.

  6. Chemical designs of functional photoactive molecular assemblies.

    PubMed

    Yan, Qifan; Luo, Zhouyang; Cai, Kang; Ma, Yuguo; Zhao, Dahui

    2014-06-21

    Molecular assemblies with well-defined structures capable of photo-induced electron transfer and charge transport or photochemical reactions are reviewed. Hierarchical supramolecular architectures, which assemble the modular units into specific spatial arrangements and facilitate them to work cooperatively, are vital for the achievement of photo-functions in these systems. The chemical design of molecular building blocks and noncovalent interactions exploited to realize supramolecular organizations are particularly discussed. Reviewing and recapitulating the chemical evolution traces of these accomplished systems will hopefully delineate certain fundamental design principles and guidelines useful for developing more advanced functions in the future. PMID:24492680

  7. The use of microfiber composites of elastin-like protein matrix reinforced with synthetic collagen in the design of vascular grafts

    PubMed Central

    Caves, Jeffrey M.; Kumar, Vivek A.; Martinez, Adam W.; Kim, Jeong; Ripberger, Carrie M.; Haller, Carolyn A.; Chaikof, Elliot L.

    2013-01-01

    Collagen and elastin networks contribute to highly specialized biomechanical responses in numerous tissues and species. Biomechanical properties such as modulus, elasticity, and strength ultimately affect tissue function and durability, as well as local cellular behavior. In the case of vascular bypass grafts, compliance at physiologic pressures is correlated with increased patency due to a reduction in anastomotic intimal hyerplasia. In this report, we combine extracellular matrix (ECM) protein analogues to yield multilamellar vascular grafts comprised of a recombinant elastin-like protein matrix reinforced with synthetic collagen microfibers. Structural analysis revealed that the fabrication scheme permits a range of fiber orientations and volume fractions, leading to tunable mechanical properties. Burst strengths of 239–2760 mm Hg, compliances of 2.8–8.4%/100 mm Hg, and suture retention strengths of 35–192 gf were observed. The design most closely approximating all target criteria displayed a burst strength of 1483 ± 43 mm Hg, a compliance of 5.1 ± 0.8%/100 mm Hg, and a suture retention strength of 173 ± 4 gf. These results indicate that through incorporation of reinforcing collagen microfibers, recombinant elastomeric protein-based biomaterials can play a significant role in load bearing tissue substitutes. We believe that similar composites can be incorporated into tissue engineering schemes that seek to integrate cells within the structure, prior to or after implantation in vivo. PMID:20584549

  8. Function through synthesis-informed design.

    PubMed

    Wender, Paul A; Quiroz, Ryan V; Stevens, Matthew C

    2015-03-17

    In 1996, a snapshot of the field of synthesis was provided by many of its thought leaders in a Chemical Reviews thematic issue on "Frontiers in Organic Synthesis". This Accounts of Chemical Research thematic issue on "Synthesis, Design, and Molecular Function" is intended to provide further perspective now from well into the 21st century. Much has happened in the past few decades. The targets, methods, strategies, reagents, procedures, goals, funding, practices, and practitioners of synthesis have changed, some in dramatic ways as documented in impressive contributions to this issue. However, a constant for most synthesis studies continues to be the goal of achieving function with synthetic economy. Whether in the form of new catalysts, reagents, therapeutic leads, diagnostics, drug delivery systems, imaging agents, sensors, materials, energy generation and storage systems, bioremediation strategies, or molecules that challenge old theories or test new ones, the function of a target has been and continues to be a major and compelling justification for its synthesis. While the targets of synthesis have historically been heavily represented by natural products, increasingly design, often inspired by natural structures, is providing a new source of target structures exhibiting new or natural functions and new or natural synthetic challenges. Complementing isolation and screening approaches to new target identification, design enables one to create targets de novo with an emphasis on sought-after function and synthetic innovation with step-economy. Design provides choice. It allows one to determine how close a synthesis will come to the ideal synthesis and how close a structure will come to the ideal function. In this Account, we address studies in our laboratory on function-oriented synthesis (FOS), a strategy to achieve function by design and with synthetic economy. By starting with function rather than structure, FOS places an initial emphasis on target design

  9. Function through Synthesis-Informed Design

    PubMed Central

    2016-01-01

    Conspectus In 1996, a snapshot of the field of synthesis was provided by many of its thought leaders in a Chemical Reviews thematic issue on “Frontiers in Organic Synthesis”. This Accounts of Chemical Research thematic issue on “Synthesis, Design, and Molecular Function” is intended to provide further perspective now from well into the 21st century. Much has happened in the past few decades. The targets, methods, strategies, reagents, procedures, goals, funding, practices, and practitioners of synthesis have changed, some in dramatic ways as documented in impressive contributions to this issue. However, a constant for most synthesis studies continues to be the goal of achieving function with synthetic economy. Whether in the form of new catalysts, reagents, therapeutic leads, diagnostics, drug delivery systems, imaging agents, sensors, materials, energy generation and storage systems, bioremediation strategies, or molecules that challenge old theories or test new ones, the function of a target has been and continues to be a major and compelling justification for its synthesis. While the targets of synthesis have historically been heavily represented by natural products, increasingly design, often inspired by natural structures, is providing a new source of target structures exhibiting new or natural functions and new or natural synthetic challenges. Complementing isolation and screening approaches to new target identification, design enables one to create targets de novo with an emphasis on sought-after function and synthetic innovation with step-economy. Design provides choice. It allows one to determine how close a synthesis will come to the ideal synthesis and how close a structure will come to the ideal function. In this Account, we address studies in our laboratory on function-oriented synthesis (FOS), a strategy to achieve function by design and with synthetic economy. By starting with function rather than structure, FOS places an initial emphasis on

  10. Design, Form, and Function in Art Education

    ERIC Educational Resources Information Center

    Vande Zande, Robin

    2007-01-01

    Human beings are influenced by design every day through continuous contact with functional form in and through visual culture. They encounter a continuous current of such new styles as clothing fashions, architecture, furniture and advertisements. The American pursuit of happiness has become related to an increasing flow of products and…

  11. Innovative Composites Through Reinforcement Morphology Design - a Bone-Shaped-Short-Fiber Composite

    SciTech Connect

    Zhu, Y.T.; Valdez, J.A.; Beyerlain, I.J.; Stout, M.G.; Zhou, S.; Shi, N.; Lowe, T.C.

    1999-06-29

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The objective of this project is to improve the strength and toughness of conventional short-fiber composites by using innovative bone-shaped-short (BSS) fibers as reinforcement. We fabricated a model polyethylene BSS fiber-reinforced polyester-matrix composite to prove that fiber morphology, instead of interfacial strength, solves the problem. Experimental tensile and fracture toughness test results show that BSS fibers can bridge matrix cracks more effectively, and consume many times more energy when pulled out, than conventional-straight-short (CSS) fibers. This leads to both higher strength and fracture toughness for the BSS-fiber composites. A computational model was developed to simulate crack propagation in both BSS- and CSS-fiber composites, accounting for stress concentrations, interface debonding, and fiber pullout. Model predictions were validated by experimental results and will be useful in optimizing BSS-fiber morphology and other material system parameters.

  12. Functionalization of Natural Graphite for Use as Reinforcement in Polymer Nanocomposites.

    PubMed

    Araujo, Rafael; Marques, Maria F V; Jonas, Renato; Grafova, Iryna; Grafov, Andriy

    2015-08-01

    Graphite is a naturally abundant material that has been used as reinforcing filler to produce polymeric nanocomposites for various applications including automotive, aerospace and electric-electronic. The objective of this study was to develop methodologies of graphite nanosheets preparation and for incorporation into polymer matrices. By means of different chemical and physical treatments, natural graphite was modified and subsequently characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetry (TGA) and the particle size determination. The results obtained clearly show that after the treatments employed, polar chemical groups were inserted on the natural graphite surface. Nanosized graphite particles of high aspect ratio were obtained. PMID:26369221

  13. Analysis of Social Variables when an Initial Functional Analysis Indicates Automatic Reinforcement as the Maintaining Variable for Self-Injurious Behavior

    ERIC Educational Resources Information Center

    Kuhn, Stephanie A. Contrucci; Triggs, Mandy

    2009-01-01

    Self-injurious behavior (SIB) that occurs at high rates across all conditions of a functional analysis can suggest automatic or multiple functions. In the current study, we conducted a functional analysis for 1 individual with SIB. Results indicated that SIB was, at least in part, maintained by automatic reinforcement. Further analyses using…

  14. Optimal seismic design of reinforced concrete structures under time-history earthquake loads using an intelligent hybrid algorithm

    NASA Astrophysics Data System (ADS)

    Gharehbaghi, Sadjad; Khatibinia, Mohsen

    2015-03-01

    A reliable seismic-resistant design of structures is achieved in accordance with the seismic design codes by designing structures under seven or more pairs of earthquake records. Based on the recommendations of seismic design codes, the average time-history responses (ATHR) of structure is required. This paper focuses on the optimal seismic design of reinforced concrete (RC) structures against ten earthquake records using a hybrid of particle swarm optimization algorithm and an intelligent regression model (IRM). In order to reduce the computational time of optimization procedure due to the computational efforts of time-history analyses, IRM is proposed to accurately predict ATHR of structures. The proposed IRM consists of the combination of the subtractive algorithm (SA), K-means clustering approach and wavelet weighted least squares support vector machine (WWLS-SVM). To predict ATHR of structures, first, the input-output samples of structures are classified by SA and K-means clustering approach. Then, WWLS-SVM is trained with few samples and high accuracy for each cluster. 9- and 18-storey RC frames are designed optimally to illustrate the effectiveness and practicality of the proposed IRM. The numerical results demonstrate the efficiency and computational advantages of IRM for optimal design of structures subjected to time-history earthquake loads.

  15. Carbon-fiber-reinforced polymer variable-curvature mirror used for optical zoom imaging: prototype design and experimental demonstration

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Fan, Xuewu; Pang, Zhihai; Ren, Guorui; Wang, Wei; Xie, Yongjie; Ma, Zhen; Du, Yunfei; Su, Yu; Wei, Jingxuan

    2015-02-01

    In recent years, optical zoom imaging without moving elements has received much attention. The key to realizing this technique lies in the design of the variable-curvature mirror (VCM). To obtain enough optical magnification, the VCM should be able to change its radius of curvature over a wide range. In other words, the VCM must be able to provide a large sagittal variation, which requires the mirror material to be robust during curvature variation, require little force to deform, and have high ultimate strength. Carbon-fiber-reinforced polymer (CFRP) satisfies all these requirements and is suitable for fabricating such a VCM. Therefore, in this research, a CFRP prototype VCM has been designed, fabricated, and tested. With a diameter of 100 mm, a thickness of 2 mm, and an initial radius of curvature of 1740 mm, this VCM can provide a maximum 23-μm sagittal variation and a minimum and maximum radius of curvature of 1705 and 1760 mm.

  16. Functional categories for future flight deck designs

    NASA Technical Reports Server (NTRS)

    Abbott, Terence S.

    1993-01-01

    With the addition of each new system on the flight deck, the danger of increasing overall operator workload while reducing crew understanding of critical mission information exists. The introduction of more powerful onboard computers, larger databases, and the increased use of electronic display media may lead to a situation of flight deck 'sophistication' at the expense of losses in flight crew capabilities and situational awareness. To counter this potentially negative impact of new technology, research activities are underway to reassess the flight deck design process. The fundamental premise of these activities is that a human-centered, systems-oriented approach to the development of advanced civil aircraft flight decks will be required for future designs to remain ergonomically sound and economically competitive. One of the initial steps in an integrated flight deck process is to define the primary flight deck functions needed to support the mission goals of the vehicle. This would allow the design team to evaluate candidate concepts in relation to their effectiveness in meeting the functional requirements. In addition, this would provide a framework to aid in categorizing and bookkeeping all of the activities that are required to be performed on the flight deck, not just activities of the crew or of a specific system. This could then allow for a better understanding and allocation of activities in the design, an understanding of the impact of a specific system on overall system performance, and an awareness of the total crew performance requirements for the design. One candidate set of functional categories that could be used to guide an advanced flight deck design are described.

  17. The design and function of birds' nests.

    PubMed

    Mainwaring, Mark C; Hartley, Ian R; Lambrechts, Marcel M; Deeming, D Charles

    2014-10-01

    All birds construct nests in which to lay eggs and/or raise offspring. Traditionally, it was thought that natural selection and the requirement to minimize the risk of predation determined the design of completed nests. However, it is becoming increasingly apparent that sexual selection also influences nest design. This is an important development as while species such as bowerbirds build structures that are extended phenotypic signals whose sole purpose is to attract a mate, nests contain eggs and/or offspring, thereby suggesting a direct trade-off between the conflicting requirements of natural and sexual selection. Nest design also varies adaptively in order to both minimize the detrimental effects of parasites and to create a suitable microclimate for parents and developing offspring in relation to predictable variation in environmental conditions. Our understanding of the design and function of birds' nests has increased considerably in recent years, and the evidence suggests that nests have four nonmutually exclusive functions. Consequently, we conclude that the design of birds' nests is far more sophisticated than previously realized and that nests are multifunctional structures that have important fitness consequences for the builder/s. PMID:25505520

  18. The design and function of birds' nests

    PubMed Central

    Mainwaring, Mark C; Hartley, Ian R; Lambrechts, Marcel M; Deeming, D Charles

    2014-01-01

    All birds construct nests in which to lay eggs and/or raise offspring. Traditionally, it was thought that natural selection and the requirement to minimize the risk of predation determined the design of completed nests. However, it is becoming increasingly apparent that sexual selection also influences nest design. This is an important development as while species such as bowerbirds build structures that are extended phenotypic signals whose sole purpose is to attract a mate, nests contain eggs and/or offspring, thereby suggesting a direct trade-off between the conflicting requirements of natural and sexual selection. Nest design also varies adaptively in order to both minimize the detrimental effects of parasites and to create a suitable microclimate for parents and developing offspring in relation to predictable variation in environmental conditions. Our understanding of the design and function of birds' nests has increased considerably in recent years, and the evidence suggests that nests have four nonmutually exclusive functions. Consequently, we conclude that the design of birds' nests is far more sophisticated than previously realized and that nests are multifunctional structures that have important fitness consequences for the builder/s. PMID:25505520

  19. Cure Cycle Design Methodology for Fabricating Reactive Resin Matrix Fiber Reinforced Composites: A Protocol for Producing Void-free Quality Laminates

    NASA Technical Reports Server (NTRS)

    Hou, Tan-Hung

    2014-01-01

    For the fabrication of resin matrix fiber reinforced composite laminates, a workable cure cycle (i.e., temperature and pressure profiles as a function of processing time) is needed and is critical for achieving void-free laminate consolidation. Design of such a cure cycle is not trivial, especially when dealing with reactive matrix resins. An empirical "trial and error" approach has been used as common practice in the composite industry. Such an approach is not only costly, but also ineffective at establishing the optimal processing conditions for a specific resin/fiber composite system. In this report, a rational "processing science" based approach is established, and a universal cure cycle design protocol is proposed. Following this protocol, a workable and optimal cure cycle can be readily and rationally designed for most reactive resin systems in a cost effective way. This design protocol has been validated through experimental studies of several reactive polyimide composites for a wide spectrum of usage that has been documented in the previous publications.

  20. Space shuttle configuration accounting functional design specification

    NASA Technical Reports Server (NTRS)

    1974-01-01

    An analysis is presented of the requirements for an on-line automated system which must be capable of tracking the status of requirements and engineering changes and of providing accurate and timely records. The functional design specification provides the definition, description, and character length of the required data elements and the interrelationship of data elements to adequately track, display, and report the status of active configuration changes. As changes to the space shuttle program levels II and III configuration are proposed, evaluated, and dispositioned, it is the function of the configuration management office to maintain records regarding changes to the baseline and to track and report the status of those changes. The configuration accounting system will consist of a combination of computers, computer terminals, software, and procedures, all of which are designed to store, retrieve, display, and process information required to track proposed and proved engineering changes to maintain baseline documentation of the space shuttle program levels II and III.

  1. Electrostatic camera system functional design study

    NASA Technical Reports Server (NTRS)

    Botticelli, R. A.; Cook, F. J.; Moore, R. F.

    1972-01-01

    A functional design study for an electrostatic camera system for application to planetary missions is presented. The electrostatic camera can produce and store a large number of pictures and provide for transmission of the stored information at arbitrary times after exposure. Preliminary configuration drawings and circuit diagrams for the system are illustrated. The camera system's size, weight, power consumption, and performance are characterized. Tradeoffs between system weight, power, and storage capacity are identified.

  2. Designing added functions in engineered cementitious composites

    NASA Astrophysics Data System (ADS)

    Yang, En-Hua

    In this dissertation, a new and systematic material design approach is developed for ECC with added functions through material microstructures linkage to composite macroscopic behavior. The thesis research embodies theoretical development by building on previous ECC micromechanical models, and experimental investigations into three specific new versions of ECC with added functions aimed at addressing societal demands of our built infrastructure. Specifically, the theoretical study includes three important ECC modeling elements: Steady-state crack propagation analyses and simulation, predictive accuracy of the fiber bridging constitutive model, and development of the rate-dependent strain-hardening criteria. The first element establishes the steady-state cracking criterion as a fundamental requirement for multiple cracking behavior in brittle matrix composites. The second element improves the accuracy of crack-width prediction in ECC. The third element establishes the micromechanics basis for impact-resistant ECC design. Three new ECCs with added functions were developed and experimentally verified in this thesis research through the enhanced theoretical framework. A green ECC incorporating a large volume of industrial waste was demonstrated to possess reduced crack width and drying shrinkage. The self-healing ECC designed with tight crack width was demonstrated to recover transport and mechanical properties after microcrack damage when exposed to wet and dry cycles. The impact-resistant ECC was demonstrated to retain tensile ductility with increased strength under moderately high strain-rate loading. These new versions of ECC with added functions are expected to contribute greatly to enhancing the sustainability, durability, and safety of civil infrastructure built with ECC. This research establishes the effectiveness of micromechanics-based design and material ingredient tailoring for ECC with added new attributes but without losing its basic tensile ductile

  3. Synthesis and Characterization of Carbon Nanotubes for Reinforced and Functional Applications

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    Many efforts have been engaged recently in synthesizing single-walled and multi-walled carbon nanotubes due to their superior mechanical, electrical and thermal properties, which could be used to enhance numerous applications such as electronics, sensors and composite strength. This presentation will show the synthesizing process of carbon nanotubes by thermal chemical vapor deposition and the characterization results by using electron microscopy and optical spectroscopy. Carbon nanotubes were synthesized on various substances. The conditions of fabricating single-walled or multi-walled carbon nanotubes depend strongly on temperatures and hydrocarbon concentrations but weakly on pressures. The size, growth modes and orientations of carbon nanotube will be illustrated. The advantages and limitations of several potential applications including sensor, heat pipe, field emission, radiation shielding, and reinforcements for composites by using carbon nanotubes will be discussed.

  4. The Measurement and Functional Properties of Reinforcer Value in Single-Alternative Responding: A Test of Linear System Theory

    ERIC Educational Resources Information Center

    Dallery, Jesse; McDowell, J. J.; Soto, Paul L.

    2004-01-01

    Matching theory and linear system theory make different predictions about how the y-asymptote, k, of Herrnstein's (1970) hyperbola varies with reinforcer value. The present experiment tested both these predictions and linear system theory's account of how reinforcement rate and reinforcer value jointly govern response rate. Eight rats served as…

  5. Functional cooperation between the hippocampal subregions and the medial septum in unreinforced and reinforced spatial memory tasks.

    PubMed

    Okada, Kana; Okaichi, Hiroshige

    2010-06-19

    Anatomical connections between the medial septum (MS) and hippocampus (Hipp) via the fimbria-fornix suggest that functional cooperation between these structures may be important for the acquisition and use of spatial reference memories. The present study examined the extent to which this was true for both an unreinforced learning task (object exploration task) and a reinforced learning task (Morris water maze task). In Experiment 1, we compared the performance of MS/Hipp contralateral- and MS/Hipp ipsilateral-lesioned rats. MS/Hipp contralateral-lesioned rats exhibited deficient performance in both the object exploration and Morris water maze tasks. In Experiment 2, we examined the task performance of MS/CA1 contralateral-, MS/CA1 ipsilateral-, MS/CA3 contralateral- and MS/CA3 ipsilateral-lesioned rats. Contralateral MS/CA3 and MS/CA1 lesions were respectively associated with deficient performance at the spatial recognition test and object recognition test in the object exploration task. None of the lesioned rats performed deficiently in the Morris water maze task. These results indicate the importance of spatial reference memory of a functional cooperation between the MS and Hipp as a whole, irrespective of reward contingency. In contrast, functional cooperation between the MS and each of CA1 and CA3 played an important role in the performance of the unreinforced voluntary task, but not in the reinforced task. Further, the functional cooperation of both MS/CA3 and MA/CA1 were important in the spatial reference memory with the unreinforced task. PMID:20144657

  6. Durability-Based Design Criteria for a Quasi-Isotropic Carbon-Fiber-Reinforced Thermoplastic Automotive Composite

    SciTech Connect

    Naus, Dan J; Corum, James; Klett, Lynn B; Davenport, Mike; Battiste, Rick; Simpson, Jr., William A

    2006-04-01

    This report provides recommended durability-based design properties and criteria for a quais-isotropic carbon-fiber thermoplastic composite for possible automotive structural applications. The composite consisted of a PolyPhenylene Sulfide (PPS) thermoplastic matrix (Fortron's PPS - Ticona 0214B1 powder) reinforced with 16 plies of carbon-fiber unidirectional tape, [0?/90?/+45?/-45?]2S. The carbon fiber was Hexcel AS-4C and was present in a fiber volume of 53% (60%, by weight). The overall goal of the project, which is sponsored by the U.S. Department of Energy's Office of Freedom Car and Vehicle Technologies and is closely coordinated with the Advanced Composites Consortium, is to develop durability-driven design data and criteria to assure the long-term integrity of carbon-fiber-based composite systems for automotive structural applications. This document is in two parts. Part 1 provides design data and correlations, while Part 2 provides the underlying experimental data and models. The durability issues addressed include the effects of short-time, cyclic, and sustained loadings; temperature; fluid environments; and low-energy impacts (e.g., tool drops and kickups of roadway debris) on deformation, strength, and stiffness. Guidance for design analysis, time-independent and time-dependent allowable stresses, rules for cyclic loadings, and damage-tolerance design guidance are provided.

  7. Optical design of optical transfer function instrument

    NASA Astrophysics Data System (ADS)

    Zhang, Liangjun; Chen, Xinhua; Chen, Yuheng; Ji, Yiqun; Xiang, Chunchang; Shen, Weimin

    2009-11-01

    The optical design of Optical transfer function (OTF) instrument, which is based on the image Fourier analysis method, is presented. To perform infinite conjugate testing of an optical system, the designed system is mainly composed of the object generator, lens under test, and image analyzer. The object generator offers an object at infinite distance with known spectral and spatial content. It includes the illumination system and the collimating system. The illumination system is analyzed and optimized with CODEV and LightTools software. Performance evaluation indicates that its illumination uniformity in the required area is above 95% .The collimation system based on an off-axis parabolic mirror is of the focal length of 2000mm and the entrance pupil diameter 200mm. Through optimization, the image quality of the collimator is excellent and its on-axis modulation transfer function (MTF) approaches diffraction limit. Collimated beam of the target is imaged by the lens under test. The image is magnified and acquired by image analyzer, which is made up of four parts: an infinite conjugate microscope objective, a tube lens, an eyepiece and a CCD camera. Image Results show that this designed scheme meets the requirements of this OTF instrument.

  8. Preserving SSC Design Function Using RCM Principles

    SciTech Connect

    Mohammadi, K

    2009-02-04

    Reliability-Centered Maintenance (RCM) can be defined as an approach that employs preventive, predictive, proactive, and reactive maintenance practices and strategies in an integrated manner to increase the probability that a Structure, System, or Component (SSC) will function as designed over its life cycle with optimum maintenance. The goal of RCM is to preserve the SSC intended design function at the lowest cost by developing a maintenance strategy that is supported by sound technical and economic justification. RCM has been used extensively by the aircraft, space, defense, power generation, and manufacturing industries where functional failures of SSCs can have the potential to compromise worker or public safety, cause adverse environmental impact, cause loss of production, and/or result in excessive damage to critical SSCs. This paper provides a framework for performing an RCM analysis in support of DOE Order 430.1A (Life Cycle Asset Management) and DOE Order 420.1B (Facility Safety). The influence of RCM on the various aspects of the maintenance program including the work control process is also discussed.

  9. Wear Properties of Intermetallic Compound Reinforced Functionally Graded Materials Fabricated by Centrifugal Solid-particle and In-Situ Methods

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshimi; Sato, Hisashi; Fukui, Yasuyoshi

    One of the functionally graded material (FGM) fabrication methods is a centrifugal method, which is an application of the centrifugal casting technique. The centrifugal force applied to a homogeneous molten composite assists the formation of the desired gradation. In this paper, the wear properties of two kinds of Al base FGMs, namely Al-Al3Ti FGM and Al-Al3Ni FGM, are reported. The former and the latter hold the oriented intermetallic compound platelets and the particle size gradient, respectively. Here, volume fraction, size, shape and orientation of the reinforcements in the composite play an important role in improving the mechanical properties of the materials, whereby FGMs with oriented platelets or particle size gradient may have special mechanical properties such as increased wear resistance. Based on the experimental results, the origin of anisotropic wear resistance and the effect of particle size on the wear properties are discussed.

  10. Characterization of hydroxyapatite whisker reinforced composites and scaffolds for mechanical and biological function in orthopaedic and spinal implants

    NASA Astrophysics Data System (ADS)

    Conrad, Timothy L.

    The overall objective of this study was to investigate the mechanical and biological properties of HA whisker reinforced polyaryletherketone (PAEK) composites and scaffolds which are key to clinical translation for orthopedic and spinal implants. The fatigue behavior of polyetherketoneketone (PEKK) reinforced with 0, 20, and 40 vol% hydroxyapatite (HA) was investigated in four-point bending fatigue. The fatigue life decreased with increasing HA reinforcement. However, PEKK reinforced with 40 vol% HA whiskers exhibited a fatigue life greater than 2.106 cycles at 40 MPa. Moreover, HA whisker reinforcement resulted in decreased creep deformation and minimal modulus degradation. The effects of the mold temperature and polyetheretherketone (PEEK) powder were investigated on the mechanical properties and crystallinity of HA whisker reinforced PEEK scaffolds prepared using compression molding and porogen leaching. The mechanical properties of the scaffolds increased while the PEEK crystallinity decreased, with increasing mold temperature and suggested an optimal mold temperature of 370--375°C for PEEK scaffolds comprising of 75% porosity and 20 vol% HA whisker reinforcement, regardless of the PEEK powder size. The effects of the porogen morphology on the architecture, mechanical properties, and permeability of HA whisker reinforced PEEK scaffolds were investigated in 75--90% porous scaffolds. HA whisker reinforced PEEK scaffolds prepared with an ellipsoidal porogen exhibited a greater permeability than scaffolds prepared with a cubic porogen. The compressive modulus, yield strength, and yield strain were not affected by the porogen morphology. The effects of HA reinforcement morphology and content was investigated on the behavior of primary osteoblasts on dense HA reinforced PEEK substrates in vitro. At day 7, the number of osteoblasts attached to PEEK substrate surfaces increased with increasing HA content and for HA whiskers compared to equiaxed HA powder reinforcement

  11. A Strategy to Support Design Processes for Fibre Reinforced Thermoset Composite Materials

    NASA Astrophysics Data System (ADS)

    Gascons, Marc; Blanco, Norbert; Mayugo, Joan Andreu; Matthys, Koen

    2012-06-01

    The concept stage in the design for a new composite part is a time when several fundamental decisions must be taken and a considerable amount of the budget is spent. Specialized commercial software packages can be used to support the decision making process in particular aspects of the project (e.g. material selection, numerical analysis, cost prediction,...). However, a complete and integrated virtual environment that covers all the steps in the process is not yet available for the composite design and manufacturing industry. This paper does not target the creation of such an overarching virtual tool, but instead presents a strategy that handles the information generated in each step of the design process, independently of the commercial packages used. Having identified a suitable design parameter shared in common with all design steps, the proposed strategy is able to evaluate the effects of design variations throughout all the design steps in parallel. A case study illustrating the strategy on an industrial part is presented.

  12. Application of composites to the selective reinforcement of metallic aerospace structures. [application of structural design criteria for weight reduction

    NASA Technical Reports Server (NTRS)

    Brooks, W. A., Jr.; Mathauser, E. E.; Pride, R. A.

    1972-01-01

    The use of composite materials to selectively reinforce metallic structures provides a low-cost way to reduce weight and a means of minimizing the risks usually associated with the introduction of new materials. An overview is presented of the NASA Langley Research Center programs to identify the advantages and to develop the potential of the selective reinforcement approach to the use of composites. These programs have shown that selective reinforcement provides excellent strength and stiffness improvements to metallic structures. Significant weight savings can be obtained in a cost effective manner. Flight service programs which have been initiated to validate further the merits of selective reinforcement are described.

  13. Designing from minimum to optimum functionality

    NASA Astrophysics Data System (ADS)

    Bannova, Olga; Bell, Larry

    2011-04-01

    This paper discusses a multifaceted strategy to link NASA Minimal Functionality Habitable Element (MFHE) requirements to a compatible growth plan; leading forward to evolutionary, deployable habitats including outpost development stages. The discussion begins by reviewing fundamental geometric features inherent in small scale, vertical and horizontal, pressurized module configuration options to characterize applicability to meet stringent MFHE constraints. A proposed scenario to incorporate a vertical core MFHE concept into an expanded architecture to provide continuity of structural form and a logical path from "minimum" to "optimum" design of a habitable module. The paper describes how habitation and logistics accommodations could be pre-integrated into a common Hab/Log Module that serves both habitation and logistics functions. This is offered as a means to reduce unnecessary redundant development costs and to avoid EVA-intensive on-site adaptation and retrofitting requirements for augmented crew capacity. An evolutionary version of the hard shell Hab/Log design would have an expandable middle section to afford larger living and working accommodations. In conclusion, the paper illustrates that a number of cargo missions referenced for NASA's 4.0.0 Lunar Campaign Scenario could be eliminated altogether to expedite progress and reduce budgets. The plan concludes with a vertical growth geometry that provides versatile and efficient site development opportunities using a combination of hard Hab/Log modules and a hybrid expandable "CLAM" (Crew Lunar Accommodations Module) element.

  14. Functional design of refractories for slagging gasifiers

    SciTech Connect

    Kwong, Kyei-Sing; Dogan, Cynthia P.; Bennett, James P.; Chinn, Richard E.; Dahlin, Cheryl L.

    2002-09-01

    Refractories are used in coal slagging gasifiers to protect the outer steel shell from coal slag attack and to insulate it from heat. Corrosion by the aggressive coal slags and unexpected temperature shock severely shorten the service life of these refractories. Currently, the best refractories available for the slagging coal gasifiers last from 6 to 18 months. The down time for the installation of new refractory lining reduces on-line availability of the gasifier. Researchers at the Albany Research Center (ARC) have found that structural spalling by slag penetration into the refractory is responsible for the early failure of refractories in some gasifiers. The low melting point of coal slags, the low thermal gradient in the refractory, and the improper design of refractory microstructure contribute to promote slag penetration. Work at ARC has demonstrated that refractories with an improved functional design are more resistant to slag penetration. Cooperation with commercial refractory companies and gasifier designers/operators is underway to produce and test improved refractories.

  15. [Influence of retainer design on fixation strength of resin-bonded glass fiber reinforced composite fixed cantilever dentures].

    PubMed

    Petrikas, O A; Voroshilin, Iu G; Petrikas, I V

    2013-01-01

    Fiber-reinforced composite (FRC) fixed partial dentures (FPD) have become an accepted part of the restorative dentist's armamentarium. The aim of this study was to evaluate in vitro the influence of retainer design on the strength of two-unit cantilever resin-bonded glass FRC-FPDs. Four retainer designs were tested: a dual wing, a dual wing + horizontal groove, a dual wing + occlusal rest and a step-box. Of each design on 7 human mandibular molars, FRC-FPDs of a premolar size were produced. The FRC framework was made of resin Revolution (Kerr) impregnated glass fibers (GlasSpan, GlasSpan) and veneered with hybrid resin composite (Charisma, Kulzer). Revolution (Kerr) was used as resin luting cement. FRC-FPDs were loaded to failure in a universal testing machine. T (Student's)-test was used to evaluate the data. The four designs were analyzed with finite element analysis (FEA) to reveal the stress distribution within the tooth/restoration complex. Significantly lower fracture strengths were observed with inlay-retained FPDs (step-box: 172±11 N) compared to wing-retained FPDs (p<0.05) (a dual wing + horizontal groove 222±9 N). The highest fracture strengths were observed with dual wing + occlusal rest FPDs: 250±10 N compared to inlay-retained FPDs (p<0.001) and wing-retained FPDs (p<0.001). FEA showed more favorable stress distributions within the tooth/restoration complex for dual wing retainers+ occlusal rest FPDs. There was stress concentration around connectors and retainers near connectors. A dual-wing retainer with occlusal rest is the optimal design for replacement of a single premolar by means of a two-unit cantilever FRC-FPDs. PMID:23715455

  16. The Use of the Direct Optimized Probabilistic Calculation Method in Design of Bolt Reinforcement for Underground and Mining Workings

    PubMed Central

    Krejsa, Martin; Janas, Petr; Yilmaz, Işık; Marschalko, Marian; Bouchal, Tomas

    2013-01-01

    The load-carrying system of each construction should fulfill several conditions which represent reliable criteria in the assessment procedure. It is the theory of structural reliability which determines probability of keeping required properties of constructions. Using this theory, it is possible to apply probabilistic computations based on the probability theory and mathematic statistics. Development of those methods has become more and more popular; it is used, in particular, in designs of load-carrying structures with the required level or reliability when at least some input variables in the design are random. The objective of this paper is to indicate the current scope which might be covered by the new method—Direct Optimized Probabilistic Calculation (DOProC) in assessments of reliability of load-carrying structures. DOProC uses a purely numerical approach without any simulation techniques. This provides more accurate solutions to probabilistic tasks, and, in some cases, such approach results in considerably faster completion of computations. DOProC can be used to solve efficiently a number of probabilistic computations. A very good sphere of application for DOProC is the assessment of the bolt reinforcement in the underground and mining workings. For the purposes above, a special software application—“Anchor”—has been developed. PMID:23935412

  17. Preliminary design methods for fiber reinforced composite structures employing a personal computer

    NASA Technical Reports Server (NTRS)

    Eastlake, C. N.

    1986-01-01

    The objective of this project was to develop a user-friendly interactive computer program to be used as an analytical tool by structural designers. Its intent was to do preliminary, approximate stress analysis to help select or verify sizing choices for composite structural members. The approach to the project was to provide a subroutine which uses classical lamination theory to predict an effective elastic modulus for a laminate of arbitrary material and ply orientation. This effective elastic modulus can then be used in a family of other subroutines which employ the familiar basic structural analysis methods for isotropic materials. This method is simple and convenient to use but only approximate, as is appropriate for a preliminary design tool which will be subsequently verified by more sophisticated analysis. Additional subroutines have been provided to calculate laminate coefficient of thermal expansion and to calculate ply-by-ply strains within a laminate.

  18. Transfer Function Design for Scientific Discovery

    SciTech Connect

    Jian Huang

    2008-12-08

    As computation scales beyond terascale, the scientific problems under study through computing are increasingly pushing the boundaries of human knowledge about the physical world. It is more pivotal than ever to quickly and reliably extract new knowledge from these complex simulations of ultra scale. In this project, the PI expanded the traditional notion of transfer function, which maps physical quantities to visual cues via table look-ups, to include general temporal as well as multivariate patterns that can be described procedurally through specialty mini programming languages. Their efforts aimed at answering a perpetual question of fundamental importance. That is "what a visualization should show". Instead of waiting for application scientists to initiate the process, the team at University of Tennessee worked closely with scientists at ORNL in a proactive role to envision and design elegant, powerful, and reliable tools that a user can use to specify "what is interesting". Their new techniques include visualization operators that revolve around correlation and graph properties, relative patterns in statistical distribution, temporal regular expressions, concurrent attribute subspaces and traditional compound boolean range queries. The team also paid special attention to ensure that all visualization operators are inherently designed with great parallel scalability to handle tera-scale datasets in both homogeneous and heterogeneous environments. Success has been demonstrated with leading edge computational science areas include climate modeling, combustion and systems genetics.

  19. Design and Analysis of Complex D-Regions in Reinforced Concrete Structures

    ERIC Educational Resources Information Center

    Yindeesuk, Sukit

    2009-01-01

    STM design provisions, such as those in Appendix A of ACI318-08, consist of rules for evaluating the capacity of the load-resisting truss that is idealized to carry the forces through the D-Region. These code rules were primarily derived from test data on simple D-Regions such as deep beams and corbels. However, these STM provisions are taken as…

  20. Sampling design optimization for spatial functions

    USGS Publications Warehouse

    Olea, R.A.

    1984-01-01

    A new procedure is presented for minimizing the sampling requirements necessary to estimate a mappable spatial function at a specified level of accuracy. The technique is based on universal kriging, an estimation method within the theory of regionalized variables. Neither actual implementation of the sampling nor universal kriging estimations are necessary to make an optimal design. The average standard error and maximum standard error of estimation over the sampling domain are used as global indices of sampling efficiency. The procedure optimally selects those parameters controlling the magnitude of the indices, including the density and spatial pattern of the sample elements and the number of nearest sample elements used in the estimation. As an illustration, the network of observation wells used to monitor the water table in the Equus Beds of Kansas is analyzed and an improved sampling pattern suggested. This example demonstrates the practical utility of the procedure, which can be applied equally well to other spatial sampling problems, as the procedure is not limited by the nature of the spatial function. ?? 1984 Plenum Publishing Corporation.

  1. Induction when Rats Respond for Liquid-Sucrose Reinforcement as a Function of Amount of Upcoming "Work"

    ERIC Educational Resources Information Center

    Weatherly, Jeffrey N.; Bauste, Grant A.; McDougall, Casey L.; Nurnberger, Jeri T.

    2006-01-01

    Previous research has shown that rats increase their rate of responding for 1% sucrose reinforcement in the first half of the session if food-pellet, rather than 1% sucrose, reinforcement will be available in the second half (i.e., positive induction). Four experiments investigated whether this induction effect would be changed by altering the…

  2. The Effects of Fixed-Time Reinforcement Schedules on Functional Response Classes: A Translational Study

    ERIC Educational Resources Information Center

    Heinicke, Megan R.; Carr, James E.; LeBlanc, Linda A.

    2012-01-01

    Research on functional response classes has applied significance because less severe forms of problem behavior have been found to co-occur with more severe forms. In addition, the most severe forms of problem behavior are sometimes targeted for intervention without monitoring other less severe forms. In such cases, it is unknown whether and how…

  3. The Effects of Consequence Manipulation during Functional Analysis of Problem Behavior Maintained by Negative Reinforcement

    ERIC Educational Resources Information Center

    Potoczak, Kathryn; Carr, James E.; Michael, Jack

    2007-01-01

    Two distinct analytic methods have been used to identify the function of problem behavior. The antecedent-behavior-consequence (ABC) method (Iwata, Dorsey, Slifer, Bauman, & Richman, 1982/1994) includes the delivery of consequences for problem behavior. The AB method (Carr & Durand, 1985) does not include consequence delivery, instead relying…

  4. The several roles of stimuli in token reinforcement.

    PubMed

    Bullock, Christopher E; Hackenberg, Timothy D

    2015-03-01

    Three experiments were conducted with pigeons to identify the stimulus functions of tokens in second-order token-reinforcement schedules. All experiments employed two-component multiple schedules with a token-reinforcement schedule in one component and a schedule with equivalent response requirements and/or reinforcer density in the other. In Experiment 1, response rates were lower under a token-reinforcement schedule than under a tandem schedule with the same response requirements, suggesting a discriminative role for the tokens. In Experiment 2, response rates varied systematically with signaling functions of the tokens in a series of conditions designed to explore other aspects of the temporal-correlative relations between tokens and food. In Experiment 3, response rates were reduced but not eliminated by presenting tokens independent of responding, yoked to their temporal occurrence in a preceding token component, suggesting both a reinforcing function and eliciting/evocative functions based on stimulus-food relations. Only when tokens were removed entirely was responding eliminated. On the whole, the results suggest that tokens, as stimuli temporally correlated with food, may serve multiple stimulus functions in token-reinforcement procedures--reinforcing, discriminative, or eliciting--depending on the precise arrangement of the contingencies in which they are embedded. PMID:25604188

  5. The design of fibre-reinforced composite blades for passive and active wind turbine rotor aerodynamic control

    NASA Astrophysics Data System (ADS)

    Karaolis, Nicos M.

    An alternative method of varying the pitch of wind turbine rotor blades is examined, which relies on the use of fiber reinforced composite materials to design the blades so as to develop elastic coupling between an applied load of a generally twisting and non-twisting nature. With such an approach, twist can be obtained either by using one of the forces experienced by the blade during operation to alter passively the blade pitch, or by internal pressurization to control actively the blade pitch by varying the pressure. The passive control option is considered in detail. First the relevant composite construction geometries that produce the desired coupling effect are identified and then a theoretical model is developed. This is also used to explore the variation in coupling and stiffness properties with the fiber orientation. Various materials are considered including glass, aramid, and carbon fiber epoxy composites. Subsequently, the structural model is confirmed experimentally by a series of tests on composite, foam-cored beams specially designed and manufactured for this purpose. It is then combined with existing aerodynamic theories in order to model the performance of horizontal and vertical axis rotors employing such blades. The effect of passively induced twist on the aerodynamic performance is examined both theoretically and experimentally. Additionally, a simplified dynamic model is developed to obtain a general idea on how built-in elastic coupling may affect the dynamic stability of a horizontal axis rotor system. The active control option is considered in general as an alternative mechanism of inducing twist. The relevant theory is derived and illustrated with examples, and the realistic practicability of this concept is discussed. To validate the theory, a composite cylindrical shell has been designed, manufactured and tested under pressure.

  6. Fiber-reinforced dielectric elastomer laminates with integrated function of actuating and sensing

    NASA Astrophysics Data System (ADS)

    Li, Tiefeng; Xie, Yuhan; Li, Chi; Yang, Xuxu; Jin, Yongbin; Liu, Junjie; Huang, Xiaoqiang

    2015-04-01

    The natural limbs of animals and insects integrate muscles, skins and neurons, providing both the actuating and sensing functions simultaneously. Inspired by the natural structure, we present a novel structure with integrated function of actuating and sensing with dielectric elastomer (DE) laminates. The structure can deform when subjected to high voltage loading and generate corresponding output signal in return. We investigate the basic physical phenomenon of dielectric elastomer experimentally. It is noted that when applying high voltage, the actuating dielectric elastomer membrane deforms and the sensing dielectric elastomer membrane changes the capacitance in return. Based on the concept, finite element method (FEM) simulation has been conducted to further investigate the electromechanical behavior of the structure.

  7. EELS Analysis of Nylon 6 Nanofibers Reinforced with Nitroxide-Functionalized Graphene Oxide.

    PubMed

    Leyva-Porras, César; Ornelas-Gutiérrez, C; Miki-Yoshida, M; Avila-Vega, Yazmín I; Macossay, Javier; Bonilla-Cruz, José

    2014-01-01

    A detailed analysis by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of nitroxide-functionalized graphene oxide layers (GOFT) dispersed in Nylon 6 nanofibers is reported herein. The functionalization and exfoliation process of graphite oxide to GOFT was confirmed by TEM using electron diffraction patterns (EDP), wherein 1 to 4 graphene layers of GOFT were observed. The distribution and alignment of GOFT layers within a sample of Nylon 6 nanofiber reveals that GOFT platelets are mainly within the fiber, but some were partially protruding from it. Furthermore, Nylon 6 nanofibers exhibit an average diameter of 225 nm with several microns in length. GOFT platelets embedded into the fiber, the pristine fiber, and amorphous carbon were analyzed by EELS where each spectra [corresponding to the carbon edge (C-K)] exhibited changes in the fine structure, allowing a clear distinction between: i) GOFT single-layers, ii) Nylon-6 nanofibers, and iii) the carbon substrate. EELS analysis is presented here for the first time as a powerful tool to identify functionalized graphene single-layers (< 4 layers of GOFT) into a Nylon 6 nanofiber composite. PMID:24634536

  8. EELS Analysis of Nylon 6 Nanofibers Reinforced with Nitroxide-Functionalized Graphene Oxide

    PubMed Central

    Leyva-Porras, César; Ornelas-Gutiérrez, C.; Miki-Yoshida, M.; Avila-Vega, Yazmín I.; Macossay, Javier; Bonilla-Cruz, José

    2014-01-01

    A detailed analysis by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) of nitroxide-functionalized graphene oxide layers (GOFT) dispersed in Nylon 6 nanofibers is reported herein. The functionalization and exfoliation process of graphite oxide to GOFT was confirmed by TEM using electron diffraction patterns (EDP), wherein 1 to 4 graphene layers of GOFT were observed. The distribution and alignment of GOFT layers within a sample of Nylon 6 nanofiber reveals that GOFT platelets are mainly within the fiber, but some were partially protruding from it. Furthermore, Nylon 6 nanofibers exhibit an average diameter of 225 nm with several microns in length. GOFT platelets embedded into the fiber, the pristine fiber, and amorphous carbon were analyzed by EELS where each spectra [corresponding to the carbon edge (C-K)] exhibited changes in the fine structure, allowing a clear distinction between: i) GOFT single-layers, ii) Nylon-6 nanofibers, and iii) the carbon substrate. EELS analysis is presented here for the first time as a powerful tool to identify functionalized graphene single-layers (< 4 layers of GOFT) into a Nylon 6 nanofiber composite. PMID:24634536

  9. Design and synthesis of supramolecular functional benzoxazines

    NASA Astrophysics Data System (ADS)

    Choi, Seong-Woo

    control of the number of phenolic functionalities. Benzoxazine monomers and polymers containing phenyl phosphine oxide are also synthesized and characterized to generate a novel class of functional polymers which have high char yield. Three different kinds of phosphorus containing phenolic derivatives, bis(4-hydroxyphenyl)phenyl phosphine oxide (BHPPO), bis(4-hydroxyphenoxyphenyl)phenyl phosphine oxide (BPPPO), and bis(4-hydroxyphenoxy)phenyl phosphine oxide (BPHPPO) are designed to elucidate structure-property relationships. The monomers are thermally initiated and polymerized via ring-opening polymerization. Thermogravimetric analysis indicates that phosphorylation has profound effect on increasing char yield.

  10. Sliding Wear Response of Beryl Reinforced Aluminum Composite - A Factorial Design Approach

    NASA Astrophysics Data System (ADS)

    Bharat, V.; Durga Prasad, B.; Prabhakar, M. Bhovi; Venkateswarlu, K.

    2016-02-01

    Al-Beryl MMCs were successfully fabricated using powder metallurgy route. Processing conditions such as beryl content and particle size were varied and its influence on dry sliding wear response was studied. Effect of test parameters like applied load and sliding distance on wear performance of Al-Beryl MMCs were discussed detail. Sliding wear tests were conducted using a pin on disc machine based on the 24 (4 factors at 2 levels) factorial design. Analysis of variance (ANOVA) was performed to obtain the contribution of control parameters on wear rate. The present study shows that wear resistance of Al-beryl MMCs not only depends on the beryl content but also influenced by normal load, sliding distance and particle size. The results show that most significant variables affecting wear rate of Al - beryl MMCs are size of the beryl particles (22%), beryl content (19.60%), sliding distance (18.47%), and normal load (10.30%). The interaction effects of these parameters are less significant in influencing wear rate compared to the individual parameters. The correlation between sliding wear and its parameters was obtained by multiple regression analysis. Regression model developed in the present study can be successfully implemented to predict the wear response of Al-Beryl MMCs.

  11. Demand for food on fixed-ratio schedules as a function of the quality of concurrently available reinforcement1

    PubMed Central

    Lea, S. E. G.; Roper, T. J.

    1977-01-01

    Six rats lever pressed for food on concurrent fixed-ratio schedules, in a two-compartment chamber. In one compartment, mixed diet pellets were delivered on fixed-ratio schedules of 1, 6, 11, and 16; in the other, either no food was delivered, or sucrose or mixed diet pellets were delivered on fixed-ratio 8. The number of pellets obtained in the first compartment declined as a function of fixed-ratio size in that compartment in all three conditions, but the decline was greatest overall with mixed diet pellets concurrently available in the other compartment, and least with no food concurrently available. The result is discussed in terms of economic demand theory, and is consistent with the prediction that elasticity of demand for a commodity (defined in operant terms as the ratio of the proportionate change in number of reinforcements per session to the proportionate change in fixed-ratio size) is greater the more substitutable for that commodity are any concurrently available commodities. PMID:16811999

  12. Processing speed enhances model-based over model-free reinforcement learning in the presence of high working memory functioning

    PubMed Central

    Schad, Daniel J.; Jünger, Elisabeth; Sebold, Miriam; Garbusow, Maria; Bernhardt, Nadine; Javadi, Amir-Homayoun; Zimmermann, Ulrich S.; Smolka, Michael N.; Heinz, Andreas; Rapp, Michael A.; Huys, Quentin J. M.

    2014-01-01

    Theories of decision-making and its neural substrates have long assumed the existence of two distinct and competing valuation systems, variously described as goal-directed vs. habitual, or, more recently and based on statistical arguments, as model-free vs. model-based reinforcement-learning. Though both have been shown to control choices, the cognitive abilities associated with these systems are under ongoing investigation. Here we examine the link to cognitive abilities, and find that individual differences in processing speed covary with a shift from model-free to model-based choice control in the presence of above-average working memory function. This suggests shared cognitive and neural processes; provides a bridge between literatures on intelligence and valuation; and may guide the development of process models of different valuation components. Furthermore, it provides a rationale for individual differences in the tendency to deploy valuation systems, which may be important for understanding the manifold neuropsychiatric diseases associated with malfunctions of valuation. PMID:25566131

  13. Effect of implant design and bioactive glass coating on biomechanical properties of fiber-reinforced composite implants.

    PubMed

    Ballo, Ahmed M; Akca, Eralp; Ozen, Tuncer; Moritz, Niko; Lassila, Lippo; Vallittu, Pekka; Närhi, Timo

    2014-08-01

    This study aimed to evaluate the influence of implant design and bioactive glass (BAG) coating on the response of bone to fiber-reinforced composite (FRC) implants. Three different FRC implant types were manufactured for the study: non-threaded implants with a BAG coating; threaded implants with a BAG coating; and threaded implants with a grit-blasted surface. Thirty-six implants (six implants for each group per time point) were installed in the tibiae of six pigs. After an implantation period of 4 and 12 wk, the implants were retrieved and prepared for micro-computed tomography (micro-CT), push-out testing, and scanning electron microscopy analysis. Micro-CT demonstrated that the screw-threads and implant structure remained undamaged during the installation. The threaded FRC/BAG implants had the highest bone volume after 12 wk of implantation. The push-out strengths of the threaded FRC/BAG implants after 4 and 12 wk (463°N and 676°N, respectively) were significantly higher than those of the threaded FRC implants (416°N and 549°N, respectively) and the nonthreaded FRC/BAG implants (219°N and 430°N, respectively). Statistically significant correlation was found between bone volume and push-out strength values. This study showed that osseointegrated FRC implants can withstand the static loading up to failure without fracture, and that the addition of BAG significantly improves the push-out strength of FRC implants. PMID:24863874

  14. Design Guidelines for In-Plane Mechanical Properties of SiC Fiber-Reinforced Melt-Infiltrated SiC Composites

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Pujar, Vijay V.

    2008-01-01

    In-plane tensile stress-strain, tensile creep, and after-creep retained tensile properties of melt-infiltrated SiC-SiC composites reinforced with different fiber types were evaluated with an emphasis on obtaining simple or first-order microstructural design guidelines for these in-plane mechanical properties. Using the mini-matrix approach to model stress-strain behavior and the results of this study, three basic general design criteria for stress and strain limits are formulated, namely a design stress limit, a design total strain limit, and an after-creep design retained strength limit. It is shown that these criteria can be useful for designing components for high temperature applications.

  15. Tank SY-101 void fraction instrument functional design criteria

    SciTech Connect

    McWethy, L.M.

    1994-10-18

    This document presents the functional design criteria for design, analysis, fabrication, testing, and installation of a void fraction instrument for Tank SY-101. This instrument will measure the void fraction in the waste in Tank SY-101 at various elevations.

  16. Slender reinforced concrete columns strengthened with fibre reinforced polymers

    NASA Astrophysics Data System (ADS)

    Gajdošová, K.; Bilčík, J.

    2011-06-01

    The requirement for a long life with relatively low maintenance costs relates to the use of building structures. Even though the structure is correctly designed, constructed and maintained, the need for extensions of its lifetime can appear. The preservation of the original structure with a higher level of resistance or reliability is enabled by strengthening. Conventional materials are replaced by progressive composites - mainly carbon fibre reinforced polymers (CFRP). They are used for strengthening reinforced concrete columns in two ways: added reinforcement in the form of CFRP strips in grooves or CFRP sheet confinement and eventually their combination. This paper presents the effect of the mentioned strengthening methods on slender reinforced concrete columns.

  17. The substitutability of reinforcers

    PubMed Central

    Green, Leonard; Freed, Debra E.

    1993-01-01

    Substitutability is a construct borrowed from microeconomics that describes a continuum of possible interactions among the reinforcers in a given situation. Highly substitutable reinforcers, which occupy one end of the continuum, are readily traded for each other due to their functional similarity. Complementary reinforcers, at the other end of the continuum, tend to be consumed jointly in fairly rigid proportion, and therefore cannot be traded for one another except to achieve that proportion. At the center of the continuum are reinforcers that are independent with respect to each other; consumption of one has no influence on consumption of another. Psychological research and analyses in terms of substitutability employ standard operant conditioning paradigms in which humans and nonhumans choose between alternative reinforcers. The range of reinforcer interactions found in these studies is more readily accommodated and predicted when behavior-analytic models of choice consider issues of substitutability. New insights are gained into such areas as eating and drinking, electrical brain stimulation, temporal separation of choice alternatives, behavior therapy, drug use, and addictions. Moreover, the generalized matching law (Baum, 1974) gains greater explanatory power and comprehensiveness when measures of substitutability are included. PMID:16812696

  18. The substitutability of reinforcers.

    PubMed

    Green, Leonard; Freed, Debra E

    1993-07-01

    Substitutability is a construct borrowed from microeconomics that describes a continuum of possible interactions among the reinforcers in a given situation. Highly substitutable reinforcers, which occupy one end of the continuum, are readily traded for each other due to their functional similarity. Complementary reinforcers, at the other end of the continuum, tend to be consumed jointly in fairly rigid proportion, and therefore cannot be traded for one another except to achieve that proportion. At the center of the continuum are reinforcers that are independent with respect to each other; consumption of one has no influence on consumption of another. Psychological research and analyses in terms of substitutability employ standard operant conditioning paradigms in which humans and nonhumans choose between alternative reinforcers. The range of reinforcer interactions found in these studies is more readily accommodated and predicted when behavior-analytic models of choice consider issues of substitutability. New insights are gained into such areas as eating and drinking, electrical brain stimulation, temporal separation of choice alternatives, behavior therapy, drug use, and addictions. Moreover, the generalized matching law (Baum, 1974) gains greater explanatory power and comprehensiveness when measures of substitutability are included. PMID:16812696

  19. Modern Physics Buildings, Design and Function.

    ERIC Educational Resources Information Center

    Palmer, R. Ronald; Rice, William Maxwell

    In order to serve college administrators, architects and physics educators, a collection was made of material reflecting the state-of-the-art of physics building design. This body of material, including drawings, diagrams, and photographs, resulted largely from extensive interviews with about 50 institutions who had recently built such facilities.…

  20. A More Realistic Lateral Load Pattern for Design of Reinforced Concrete Buildings with Moment Frames and Shear Walls

    SciTech Connect

    Hosseini, Mahmood

    2008-07-08

    In this research it has been tried to find a more realistic distribution pattern for the seismic load in reinforced concrete (R/C) buildings, having moment frames with shear walls as their lateral resisting system, by using Nonlinear Time History Analyses (NLTHA). Having shear wall as lateral load bearing system decreases the effect of infill walls in the seismic behavior of the building, and therefore the case of buildings with shear walls has been considered for this study as the first stage of the studies on lateral load patterns for R/C buildings. For this purpose, by assuming three different numbers of bays in each direction and also three different numbers of stories for the buildings, several R/C buildings, have been studied. At first, the buildings have been designed by the Iranian National Code for R/C Buildings. Then they have been analyzed by a NLTHA software using the accelerograms of some well-known earthquakes. The used accelerograms have been also scaled to various levels of peak ground acceleration (PGA) such as 0.35 g, 0.50 g, and 0.70 g, to find out the effect of PGA in the seismic response. Numerical results have shown that firstly the values of natural period of the building and their shear force values, calculated by the code, are not appropriate in all cases. Secondly, it has been found out that the real lateral load pattern is quite different with the one suggested by the seismic code. Based on the NLTHA results a new lateral load pattern has been suggested for this kind of buildings, in the form of some story-dependent modification factors applied to the existing code formula. The effects of building's natural period, as well as its number of stories, are taken into account explicitly in the proposed new load pattern. The proposed load pattern has been employed to redesign the buildings and again by NLTHA the real lateral load distribution in each case has been obtained which has shown very good agreement with the proposed pattern.

  1. Reinforced Stimulus Preexposure Effects as a Function of US Intensity: Implications for Understanding the Hall-Pearce Effect

    ERIC Educational Resources Information Center

    Rodriguez, Gabriel; Alonso, Gumersinda

    2011-01-01

    Three conditioned suppression experiments examined the Hall-Pearce (1979) negative transfer effect in rats. Experiment 1 replicated the effect: CS-US[subscript weak] pairings retarded subsequent fear conditioning to the CS as a result of CS-US[subscript strong] pairings. The size of this retardation was less than that produced by non-reinforced CS…

  2. Computational approaches for rational design of proteins with novel functionalities

    PubMed Central

    Tiwari, Manish Kumar; Singh, Ranjitha; Singh, Raushan Kumar; Kim, In-Won; Lee, Jung-Kul

    2012-01-01

    Proteins are the most multifaceted macromolecules in living systems and have various important functions, including structural, catalytic, sensory, and regulatory functions. Rational design of enzymes is a great challenge to our understanding of protein structure and physical chemistry and has numerous potential applications. Protein design algorithms have been applied to design or engineer proteins that fold, fold faster, catalyze, catalyze faster, signal, and adopt preferred conformational states. The field of de novo protein design, although only a few decades old, is beginning to produce exciting results. Developments in this field are already having a significant impact on biotechnology and chemical biology. The application of powerful computational methods for functional protein designing has recently succeeded at engineering target activities. Here, we review recently reported de novo functional proteins that were developed using various protein design approaches, including rational design, computational optimization, and selection from combinatorial libraries, highlighting recent advances and successes. PMID:24688643

  3. Functional design specification: NASA form 1510

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The 1510 worksheet used to calculate approved facility project cost estimates is explained. Topics covered include data base considerations, program structure, relationship of the 1510 form to the 1509 form, and functions which the application must perform: WHATIF, TENENTER, TENTYPE, and data base utilities. A sample NASA form 1510 printout and a 1510 data dictionary are presented in the appendices along with the cost adjustment table, the floppy disk index, and methods for generating the calculated values (TENCALC) and for calculating cost adjustment (CONSTADJ). Storage requirements are given.

  4. UML Profiles for Design Decisions and Non-Functional Requirements

    SciTech Connect

    Zhu, Liming; Gorton, Ian

    2007-06-30

    A software architecture is composed of a collection of design decisions. Each design decision helps or hinders certain Non-Functional Requirements (NFR). Current software architecture views focus on expressing components and connectors in the system. Design decisions and their relationships with non-functional requirements are often captured in separate design documentation, not explicitly expressed in any views. This disassociation makes architecture comprehension and architecture evolution harder. In this paper, we propose a UML profile for modeling design decisions and an associated UML profile for modeling non-functional requirements in a generic way. The two UML profiles treat design decisions and nonfunctional requirements as first-class elements. Modeled design decisions always refer to existing architectural elements and thus maintain traceability between the two. We provide a mechanism for checking consistency over this traceability. An exemplar is given as

  5. Role of the Dorsal Medial Habenula in the Regulation of Voluntary Activity, Motor Function, Hedonic State, and Primary Reinforcement

    PubMed Central

    Hsu, Yun-Wei A.; Wang, Si D.; Wang, Shirong; Morton, Glenn; Zariwala, Hatim A.; de la Iglesia, Horacio O.

    2014-01-01

    The habenular complex in the epithalamus consists of distinct regions with diverse neuronal populations. Past studies have suggested a role for the habenula in voluntary exercise motivation and reinforcement of intracranial self-stimulation but have not assigned these effects to specific habenula subnuclei. Here, we have developed a genetic model in which neurons of the dorsal medial habenula (dMHb) are developmentally eliminated, via tissue-specific deletion of the transcription factor Pou4f1 (Brn3a). Mice with dMHb lesions perform poorly in motivation-based locomotor behaviors, such as voluntary wheel running and the accelerating rotarod, but show only minor abnormalities in gait and balance and exhibit normal levels of basal locomotion. These mice also show deficits in sucrose preference, but not in the forced swim test, two measures of depression-related phenotypes in rodents. We have also used Cre recombinase-mediated expression of channelrhodopsin-2 and halorhodopsin to activate dMHb neurons or silence their output in freely moving mice, respectively. Optical activation of the dMHb in vivo supports intracranial self-stimulation, showing that dMHb activity is intrinsically reinforcing, whereas optical silencing of dMHb outputs is aversive. Together, our findings demonstrate that the dMHb is involved in exercise motivation and the regulation of hedonic state, and is part of an intrinsic reinforcement circuit. PMID:25143617

  6. Parametric Cost Analysis: A Design Function

    NASA Technical Reports Server (NTRS)

    Dean, Edwin B.

    1989-01-01

    Parametric cost analysis uses equations to map measurable system attributes into cost. The measures of the system attributes are called metrics. The equations are called cost estimating relationships (CER's), and are obtained by the analysis of cost and technical metric data of products analogous to those to be estimated. Examples of system metrics include mass, power, failure_rate, mean_time_to_repair, energy _consumed, payload_to_orbit, pointing_accuracy, manufacturing_complexity, number_of_fasteners, and percent_of_electronics_weight. The basic assumption is that a measurable relationship exists between system attributes and the cost of the system. If a function exists, the attributes are cost drivers. Candidates for metrics include system requirement metrics and engineering process metrics. Requirements are constraints on the engineering process. From optimization theory we know that any active constraint generates cost by not permitting full optimization of the objective. Thus, requirements are cost drivers. Engineering processes reflect a projection of the requirements onto the corporate culture, engineering technology, and system technology. Engineering processes are an indirect measure of the requirements and, hence, are cost drivers.

  7. Design of polypeptide-functionalized polystyrene microspheres.

    PubMed

    Bousquet, A; Perrier-Cornet, R; Ibarboure, E; Papon, E; Labrugère, C; Héroguez, V; Rodríguez-Hernández, J

    2008-07-01

    In this contribution, the principle of spontaneous surface segregation has been applied for the preparation of polypeptide-functionalized polystyrene microspheres. For that purpose, an amphiphilic diblock copolymer was introduced in the mixture styrene/divinylbenzene and polymerized using AIBN as initiator. During the polymerization, cross-linked particles were obtained in which the diblock copolymer was encapsulated. The amphiphilic diblock copolymers used throughout this study contain a hydrophilic polypeptide segment, either poly(L-lysine) or poly(L-glutamic acid) and a hydrophobic polystyrene block. After 4 h of polymerization, rather monodisperse particles with sizes of approximately 3-4 microm were obtained. Upon annealing in hot water, the hydrophilic polypeptides migrate to the interface, hence, either positively charged or neutral particles were obtained when poly(L-lysine) is revealed at the surface and exposed to acidic or basic pH, respectively. On the opposite, negatively charged particles were achieved in basic pH water by using poly(L-glutamic acid) as additive. The surface chemical composition was modified by changing the environment of the particles. Thus, exposure in toluene provoked a surface rearrangement, and due to its affinity, the polystyrene block reorients toward the interface. PMID:18517246

  8. On singular cases in the design derivative of Green's functional

    NASA Technical Reports Server (NTRS)

    Reiss, Robert

    1987-01-01

    The author's prior development of a general abstract representation for the design sensitivities of Green's functional for linear structural systems is extended to the case where the structural stiffness vanishes at an internal location. This situation often occurs in the optimal design of structures. Most optimality criteria require that optimally designed beams be statically determinate. For clamped-pinned beams, for example, this is possible only if the flexural stiffness vanishes at some intermediate location. The Green's function for such structures depends upon the stiffness and the location where it vanishes. A precise representation for Green's function's sensitivity to the location of vanishing stiffness is presented for beams and axisymmetric plates.

  9. Rational and Mechanistic Perspectives on Reinforcement Learning

    ERIC Educational Resources Information Center

    Chater, Nick

    2009-01-01

    This special issue describes important recent developments in applying reinforcement learning models to capture neural and cognitive function. But reinforcement learning, as a theoretical framework, can apply at two very different levels of description: "mechanistic" and "rational." Reinforcement learning is often viewed in mechanistic terms--as…

  10. Strength analysis and design of adhesive joints between circular elements made of metal and reinforced polymer materials

    NASA Astrophysics Data System (ADS)

    Pelekh, B. L.; Marchuk, M. V.; Kogut, I. S.

    1992-06-01

    The stress-strain state of an adhesive joint between cylindrical components made of a metal (steel) and a cross-reinforced filament-wound composite (glass/polymer or basalt/polymer) was investigated under static axial loading using newly proposed experimental techniques and a refined mathematical model. Analytical expressions are obtained for contact stresses in the adhesive joint. The maximum permissible load and the ultimate shear strength of the joint are determined. The experimental results are found to be in satisfactory agreement with model predictions.

  11. Safety goals and functional performance criteria. [Advanced Reactor Design

    SciTech Connect

    Youngblood, R.W.; Pratt, W.T. ); Hardin, W.B. . Div. of Regulatory Applications)

    1990-01-01

    This report discusses a possible approach to the development of functional performance criteria to be applied to evolutionary LWR designs. Key safety functions are first identified; then, criteria are drawn up for each individual function, based on the premise that no single function's projected unreliability should be allowed to exhaust the safety goal frequencies. In the area of core damage prevention, functional criteria are cast in terms of necessary levels of redundancy and diversity of critical equipment. In the area of core damage mitigation (containment), functional performance criteria are cast with the aim of mitigating post-core-melt phenomena with sufficient assurance to eliminate major uncertainties in containment performance. 9 refs.

  12. Ethical considerations for a better collaboration between architects and structural engineers: design of buildings with reinforced concrete frame systems in earthquake zones.

    PubMed

    Hurol, Yonca

    2014-06-01

    Architects design building structures, although structural design is the profession of structural engineers. Thus, it is better for architects and structural engineers to collaborate starting from the initial phases of the architectural design. However, this is not very common because of the contradictory design processes and value systems held within the two professions. This article provides a platform upon which architects and structural engineers can resolve the value conflicts between them by analysing phases of the structural design of reinforced concrete frame systems in architecture, the criteria of the structural design for each phase and determining the conflicting values for each criterion. The results shown in the article demonstrate that the architectural design of structures is a complex process, which is based on contradictory values and value systems. Finally, the article suggests to architects and structural engineers to use Value Sensitive Design and to choose an appropriate team leader in order to resolve the unethical conflict between them and to avoid any unreasonable decision making. PMID:23700122

  13. Collateral gains and short-term maintenance in reading and on-task responses by inner-city adolescents as a function of their use of social reinforcement while tutoring.

    PubMed Central

    Greer, R D; Polirstok, S R

    1982-01-01

    Two experiments are reported concerning the effects of the differential use of verbal approval by problematic adolescents serving as tutors in a remedial reading program for an inner-city school. The experiments, each with 3 tutors and 15 tutees, used a combined multiple baseline and ABCBC design. Data showed that tutors' approvals as well as tutors' and tutees' on-task and reading responses were low and stable during baseline. Tutors were trained to use verbal approval for tutees' on-task behavior. Tokens were presented and withdrawn to control the tutors' use of approval. During phases in which tutors' approvals were raised via token dispensation, tutor reading and on-task scores increased in a nonexperimental setting. Tutee reading scores also increased as a function of tutor approvals. The second experiment replicated these findings and, in addition, (a) tested the validity of changes in reading responses via standardized tests, (b) isolated and compared the covariance between variables in all phases, and (c) provided data on tutee attention to tutors as a possible natural reinforcer for short-term maintenance found in both studies. Data are discussed as evidence that tutors had acquired the ability to recruit reinforcement from the classroom for appropriate behavior. PMID:7096224

  14. Thermal Characterization of Functionally Graded Materials: Design of Optimum Experiments

    NASA Technical Reports Server (NTRS)

    Cole, Kevin D.

    2003-01-01

    This paper is a study of optimal experiment design applied to the measure of thermal properties in functionally graded materials. As a first step, a material with linearly-varying thermal properties is analyzed, and several different tran- sient experimental designs are discussed. An optimality criterion, based on sen- sitivity coefficients, is used to identify the best experimental design. Simulated experimental results are analyzed to verify that the identified best experiment design has the smallest errors in the estimated parameters. This procedure is general and can be applied to design of experiments for a variety of materials.

  15. Is function-based control room design human-centered?

    SciTech Connect

    Norros, L.; Savioja, P.

    2006-07-01

    Function-based approaches to system interface design appears an appealing possibility in helping designers and operators to cope with the vast amount of information needed to control complex processes. In this paper we provide evidence of operator performance analyses showing that outcome-centered performance measures may not be sufficiently informative for design. We need analyses indicating habitual patterns of using information, operator practices. We argue that practices that portray functional orienting to the task support mastery of the process. They also create potential to make use of function-based information presentation. We see that functional design is not an absolute value. Instead, such design should support communication of the functional significance of the process information to the operators in variable situations. Hence, it should facilitate development of practices that focus to interpreting this message. Successful function-based design facilitates putting operations into their contexts and is human-centered in an extended sense: It aids making sense in the complex, dynamic and uncertain environment. (authors)

  16. Computational design of proteins with novel structure and functions

    NASA Astrophysics Data System (ADS)

    Wei, Yang; Lu-Hua, Lai

    2016-01-01

    Computational design of proteins is a relatively new field, where scientists search the enormous sequence space for sequences that can fold into desired structure and perform desired functions. With the computational approach, proteins can be designed, for example, as regulators of biological processes, novel enzymes, or as biotherapeutics. These approaches not only provide valuable information for understanding of sequence-structure-function relations in proteins, but also hold promise for applications to protein engineering and biomedical research. In this review, we briefly introduce the rationale for computational protein design, then summarize the recent progress in this field, including de novo protein design, enzyme design, and design of protein-protein interactions. Challenges and future prospects of this field are also discussed. Project supported by the National Basic Research Program of China (Grant No. 2015CB910300), the National High Technology Research and Development Program of China (Grant No. 2012AA020308), and the National Natural Science Foundation of China (Grant No. 11021463).

  17. Canberra Alpha Sentry Installation Functional Design Criteria (FDC)

    SciTech Connect

    WHITE, W.F.

    1999-12-16

    This document provides the functional design criteria for the installation of the Canberra Alpha Sentry System at selected locations within the Plutonium Finishing Plant (PFP). The equipment being installed is identified by part number in Section 3 and the locations are given in Section 5. The design, procurement and installation are assigned to Fluor Federal Services.

  18. BEHAVIORAL MECHANISMS UNDERLYING NICOTINE REINFORCEMENT

    PubMed Central

    Rupprecht, Laura E.; Smith, Tracy T.; Schassburger, Rachel L.; Buffalari, Deanne M.; Sved, Alan F.; Donny, Eric C.

    2015-01-01

    Cigarette smoking is the leading cause of preventable deaths worldwide and nicotine, the primary psychoactive constituent in tobacco, drives sustained use. The behavioral actions of nicotine are complex and extend well beyond the actions of the drug as a primary reinforcer. Stimuli that are consistently paired with nicotine can, through associative learning, take on reinforcing properties as conditioned stimuli. These conditioned stimuli can then impact the rate and probability of behavior and even function as conditioning reinforcers that maintain behavior in the absence of nicotine. Nicotine can also act as a conditioned stimulus, predicting the delivery of other reinforcers, which may allow nicotine to acquire value as a conditioned reinforcer. These associative effects, establishing non-nicotine stimuli as conditioned stimuli with discriminative stimulus and conditioned reinforcing properties as well as establishing nicotine as a conditioned stimulus, are predicted by basic conditioning principles. However, nicotine can also act non-associatively. Nicotine directly enhances the reinforcing efficacy of other reinforcing stimuli in the environment, an effect that does not require a temporal or predictive relationship between nicotine and either the stimulus or the behavior. Hence, the reinforcing actions of nicotine stem both from the primary reinforcing actions of the drug (and the subsequent associative learning effects) as well as the reinforcement enhancement action of nicotine which is non-associative in nature. Gaining a better understanding of how nicotine impacts behavior will allow for maximally effective tobacco control efforts aimed at reducing the harm associated with tobacco use by reducing and/or treating its addictiveness. PMID:25638333

  19. Negative effects of positive reinforcement

    PubMed Central

    Perone, Michael

    2003-01-01

    Procedures classified as positive reinforcement are generally regarded as more desirable than those classified as aversive—those that involve negative reinforcement or punishment. This is a crude test of the desirability of a procedure to change or maintain behavior. The problems can be identified on the basis of theory, experimental analysis, and consideration of practical cases. Theoretically, the distinction between positive and negative reinforcement has proven difficult (some would say the distinction is untenable). When the distinction is made purely in operational terms, experiments reveal that positive reinforcement has aversive functions. On a practical level, positive reinforcement can lead to deleterious effects, and it is implicated in a range of personal and societal problems. These issues challenge us to identify other criteria for judging behavioral procedures. ImagesFigure 1Figure 2 PMID:22478391

  20. Stress-resultant models for ultimate load design of reinforced concrete frames and multi-scale parameter estimates

    NASA Astrophysics Data System (ADS)

    Pham, B. H.; Brancherie, D.; Davenne, L.; Ibrahimbegovic, A.

    2013-03-01

    In this work, we present a new finite element for (geometrically linear) Timoshenko beam model for ultimate load computation of reinforced concrete frames. The proposed model combines the descriptions of the diffuse plastic failure in the beam-column followed by the creation of plastic hinges due to the failure or collapse of the concrete and of the re-bars. A modified multi-scale analysis is performed in order to identify the parameters for stress-resultant-based macro model, which is used to described the behavior of the Timoshenko beam element. For clarity, we focus upon the micro-scale models using the multi-fiber elements with embedded displacement discontinuities in mode I, which would typically be triggered by bending failure mode. More general case of micro-scale model capable of describing shear failure is described by Ibrahimbegovic et al. (Int J Numer Methods Eng 83(4):452-481, 2010).

  1. Designing of epoxy composites reinforced with carbon nanotubes grown carbon fiber fabric for improved electromagnetic interference shielding

    NASA Astrophysics Data System (ADS)

    Singh, B. P.; Choudhary, Veena; Saini, Parveen; Mathur, R. B.

    2012-06-01

    In this letter, we report preparation of strongly anchored multiwall carbon nanotubes (MWCNTs) carbon fiber (CF) fabric preforms. These preforms were reinforced in epoxy resin to make multi scale composites for microwave absorption in the X-band (8.2-12.4GHz). The incorporation of MWCNTs on the carbon fabric produced a significant enhancement in the electromagnetic interference shielding effectiveness (EMI-SE) from -29.4 dB for CF/epoxy-composite to -51.1 dB for CF-MWCNT/epoxy multiscale composites of 2 mm thickness. In addition to enhanced EMI-SE, interlaminar shear strength improved from 23 MPa for CF/epoxy-composites to 50 MPa for multiscale composites indicating their usefulness for making structurally strong microwave shields.

  2. Function combined method for design innovation of children's bike

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoli; Qiu, Tingting; Chen, Huijuan

    2013-03-01

    As children mature, bike products for children in the market develop at the same time, and the conditions are frequently updated. Certain problems occur when using a bike, such as cycle overlapping, repeating function, and short life cycle, which go against the principles of energy conservation and the environmental protection intensive design concept. In this paper, a rational multi-function method of design through functional superposition, transformation, and technical implementation is proposed. An organic combination of frog-style scooter and children's tricycle is developed using the multi-function method. From the ergonomic perspective, the paper elaborates on the body size of children aged 5 to 12 and effectively extracts data for a multi-function children's bike, which can be used for gliding and riding. By inverting the body, parts can be interchanged between the handles and the pedals of the bike. Finally, the paper provides a detailed analysis of the components and structural design, body material, and processing technology of the bike. The study of Industrial Product Innovation Design provides an effective design method to solve the bicycle problems, extends the function problems, improves the product market situation, and enhances the energy saving feature while implementing intensive product development effectively at the same time.

  3. The Functional Requirements and Design Basis for Information Barriers

    SciTech Connect

    Fuller, James L.

    2012-05-01

    This report summarizes the results of the Information Barrier Working Group workshop held at Sandia National Laboratory in Albuquerque, NM, February 2-4, 1999. This workshop was convened to establish the functional requirements associated with warhead radiation signature information barriers, to identify the major design elements of any such system or approach, and to identify a design basis for each of these major elements. Such information forms the general design basis to be used in designing, fabricating, and evaluating the complete integrated systems developed for specific purposes.

  4. Tokens for Success: Using the Graduated Reinforcement System.

    ERIC Educational Resources Information Center

    Lyon, Carla S.; Lagarde, Renee

    1997-01-01

    Describes the Graduated Reinforcement System, a simplifed token system that involves establishing a partnership with parents and students, identifying target behaviors, planning for record keeping, tallying daily/weekly points, designating the graduated reinforcement criteria, determining reinforcers for the three levels, awarding the reinforcer,…

  5. A Comparison of Functional Models for Use in the Function-Failure Design Method

    NASA Technical Reports Server (NTRS)

    Stock, Michael E.; Stone, Robert B.; Tumer, Irem Y.

    2006-01-01

    When failure analysis and prevention, guided by historical design knowledge, are coupled with product design at its conception, shorter design cycles are possible. By decreasing the design time of a product in this manner, design costs are reduced and the product will better suit the customer s needs. Prior work indicates that similar failure modes occur with products (or components) with similar functionality. To capitalize on this finding, a knowledge base of historical failure information linked to functionality is assembled for use by designers. One possible use for this knowledge base is within the Elemental Function-Failure Design Method (EFDM). This design methodology and failure analysis tool begins at conceptual design and keeps the designer cognizant of failures that are likely to occur based on the product s functionality. The EFDM offers potential improvement over current failure analysis methods, such as FMEA, FMECA, and Fault Tree Analysis, because it can be implemented hand in hand with other conceptual design steps and carried throughout a product s design cycle. These other failure analysis methods can only truly be effective after a physical design has been completed. The EFDM however is only as good as the knowledge base that it draws from, and therefore it is of utmost importance to develop a knowledge base that will be suitable for use across a wide spectrum of products. One fundamental question that arises in using the EFDM is: At what level of detail should functional descriptions of components be encoded? This paper explores two approaches to populating a knowledge base with actual failure occurrence information from Bell 206 helicopters. Functional models expressed at various levels of detail are investigated to determine the necessary detail for an applicable knowledge base that can be used by designers in both new designs as well as redesigns. High level and more detailed functional descriptions are derived for each failed component based

  6. Systematic Description of Functional Knowledge based on Functional Ontologies and Its Use for Supporting Design of Functional Structures

    NASA Astrophysics Data System (ADS)

    Kitamura, Yoshinobu; Kasai, Toshinobu; Yoshikawa, Mariko; Takahashi, Masaru; Kozaki, Kouji; Mizoguchi, Riichiro

    In conceptual design, a designer decomposes a required function into sub-functions, so-called functional decomposition, using a kind of functional knowledge representing achievement relations among functions. Aimin at systematization of such functional knowledge, we proposed ontologies that guide conceptualization of artifacts from the functional point of view. This paper discusses its systematic description based on the functional ontologies. Firstly, we propose a new concept named “way of achievement” as a key concept for its systematization. Categorization of typical representations of the knowledge and organization as is-a hierarchies are also discussed. Such concept, categorization, and functional ontologies make the functional knowledge consistent and applicable to other domains. Next, the implementation of the functional ontologies and their utility on description of the knowledge are shown. Lastly, we discuss development of a knowledge-based system to help human designers redesign an existin artifact. The ontology of functional concepts and the systematic description of functional knowledge enable the supporting system to show designers a wide range of alternative ways and then to facilitate innovative redesign.

  7. Excitotoxic lesions of the medial striatum delay extinction of a reinforcement color discrimination operant task in domestic chicks; a functional role of reward anticipation.

    PubMed

    Ichikawa, Yoko; Izawa, Ei-Ichi; Matsushima, Toshiya

    2004-12-01

    To reveal the functional roles of the striatum, we examined the effects of excitotoxic lesions to the bilateral medial striatum (mSt) and nucleus accumbens (Ac) in a food reinforcement color discrimination operant task. With a food reward as reinforcement, 1-week-old domestic chicks were trained to peck selectively at red and yellow beads (S+) and not to peck at a blue bead (S-). Those chicks then received either lesions or sham operations and were tested in extinction training sessions, during which yellow turned out to be nonrewarding (S-), whereas red and blue remained unchanged. To further examine the effects on postoperant noninstrumental aspects of behavior, we also measured the "waiting time", during which chicks stayed at the empty feeder after pecking at yellow. Although the lesioned chicks showed significantly higher error rates in the nonrewarding yellow trials, their postoperant waiting time gradually decreased similarly to the sham controls. Furthermore, the lesioned chicks waited significantly longer than the controls, even from the first extinction block. In the blue trials, both lesioned and sham chicks consistently refrained from pecking, indicating that the delayed extinction was not due to a general disinhibition of pecking. Similarly, no effects were found in the novel training sessions, suggesting that the lesions had selective effects on the extinction of a learned operant. These results suggest that a neural representation of memory-based reward anticipation in the mSt/Ac could contribute to the anticipation error required for extinction. PMID:15561503

  8. Single Dose of a Dopamine Agonist Impairs Reinforcement Learning in Humans: Evidence from Event-related Potentials and Computational Modeling of Striatal-Cortical Function

    PubMed Central

    Santesso, Diane L.; Evins, A. Eden; Frank, Michael J.; Cowman Schetter, Erika M.; Bogdan, Ryan; Pizzagalli, Diego A.

    2011-01-01

    Animal findings have highlighted the modulatory role of phasic dopamine (DA) signaling in incentive learning, particularly in the acquisition of reward-related behavior. In humans, these processes remain largely unknown. In a recent study we demonstrated that a single low dose of a D2/D3 agonist (pramipexole) – assumed to activate DA autoreceptors and thus reduce phasic DA bursts – impaired reward learning in healthy subjects performing a probabilistic reward task. The purpose of the present study was to extend these behavioral findings using event-related potentials and computational modeling. Compared to the placebo group, participants receiving pramipexole showed increased feedback-related negativity to probabilistic rewards and decreased activation in dorsal anterior cingulate regions previously implicated in integrating reinforcement history over time. Additionally, findings of blunted reward learning in participants receiving pramipexole were simulated by reduced presynaptic DA signaling in response to reward in a neural network model of striatal-cortical function. These preliminary findings offer important insights on the role of phasic DA signals on reinforcement learning in humans, and provide initial evidence regarding the spatio-temporal dynamics of brain mechanisms underlying these processes. PMID:18726908

  9. Highly specific role of hypocretin (orexin) neurons: differential activation as a function of diurnal phase, operant reinforcement vs. operant avoidance and light level

    PubMed Central

    McGregor, Ronald; Wu, Ming-Fung; Barber, Grace; Ramanathan, Lalini; Siegel, Jerome M.

    2011-01-01

    Hypocretin (Hcrt) cell loss is responsible for narcolepsy, but Hcrt's role in normal behavior is unclear. We found that Hcrt KO mice were unable to work for food or water reward during the light phase. However, they were unimpaired relative to wild type (WT) mice when working for reward during the dark phase or when working to avoid shock in the light or dark phases. In WT, expression of Fos in Hcrt neurons occurs only in the light phase when working for positive reinforcement. Expression was seen throughout the medio-lateral extent of the Hcrt field. Fos was not expressed when expected or unexpected, unearned rewards were presented, when working to avoid negative reinforcement, or when given or expecting shock, even though these conditions elicit maximal electroencephalographic (EEG) arousal. Fos was not expressed in the light phase when light was removed. This may explain the lack of light induced arousal in narcoleptics and its presence in normal individuals. This is the first demonstration of such specificity of arousal system function and has implications for understanding the motivational and circadian consequences of arousal system dysfunction. The current results also indicate that comparable and complementary specificities must exist in other “arousal” systems. PMID:22031892

  10. Hyperbolic tangential function-based progressive addition lens design.

    PubMed

    Qiu, Gufeng; Cui, Xudong

    2015-12-10

    The diopter distribution is key to the successful design of a progressive addition lens. A hyperbolic tangential function is then introduced to describe well the desired diopter distribution on the lens. Simulation and fabrication show that the astigmia on the whole surface is very close to the addition, exhibiting superior performance than that of currently used high-order polynomials and cosine functions. Our investigations found that once the diopter distribution design is reasonable, both the direct and indirect methods of constructing a progressive addition lens can give consistent results. With this function we are able to effectively control the design of critical areas, the position, sizes of far-view and near-view zones, as well as the channel of the lens. This study would provide an efficient way to customize different progressive lenses not only for presbyopia, but also for anti-fatigue, office progressive usages, etc. PMID:26836863

  11. Rational Design of Graphene-Reinforced MnO Nanowires with Enhanced Electrochemical Performance for Li-Ion Batteries.

    PubMed

    Sun, Qi; Wang, Zhijie; Zhang, Zijiao; Yu, Qian; Qu, Yan; Zhang, Jingyu; Yu, Yan; Xiang, Bin

    2016-03-01

    Recently, transition metal oxides (TMOs) mixed with carbon materials have attracted attention as lithium-ion battery (LIB) anode materials. However, the aggregation issue in TMOs hinders the development of an ideal encapsulation structure with carbon materials. In this paper, we report graphene reinforced MnO nanowires with enhanced electrochemical performance as an anode in LIB. The graphene nanosheets (GNs)/MnO feature was confirmed by transmission electron microscopy, X-ray diffraction, Raman scattering, and X-ray photoelectron spectroscopy. The GNs/MnO nanowires delivered a highly stable discharge capacity of ∼815 mAh g(-1) at a current density of 100 mA g(-1) after 200 cycles, which is 1.5 times higher than that of pure MnO nanowires. This GNs/MnO structure with a specific capacity of ∼995 mAh g(-1) at a current density of 50 mA g(-1) also exhibited excellent Li storage properties. The superior cycling and high rate capability were attributed to the intimate incorporation between the MnO and GNs. The structure of the GNs/MnO nanowires effectively accommodated the volume change of the MnO nanowires and prevented structure collapse during cycling. PMID:26894410

  12. Improved Mechanical Properties of Various Fabric-Reinforced Geocomposite at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Samal, Sneha; Phan Thanh, Nhan; Petríková, Iva; Marvalová, Bohadana

    2015-07-01

    This article signifies the improved performance of the various types of fabric reinforcement of geopolymer as a function of physical, thermal, mechanical, and heat-resistant properties at elevated temperatures. Geopolymer mixed with designed Si:Al ratios of 15.6 were synthesized using three different types of fabric reinforcement such as carbon, E-glass, and basalt fibers. Heat testing was conducted on 3-mm-thick panels with 15 × 90 mm surface exposure region. The strength of carbon-based geocomposite increased toward a higher temperature. The basalt-reinforced geocomposite strength decreased due to the catastrophic failure in matrix region. The poor bridging effect and dissolution of fabric was observed in the E-glass-reinforced geocomposite. At an elevated temperature, fiber bridging was observed in carbon fabric-reinforced geopolymer matrix. Among all the fabrics, carbon proved to be suitable candidate for the high-temperature applications in thermal barrier coatings and fire-resistant panels.

  13. Complete RNA inverse folding: computational design of functional hammerhead ribozymes

    PubMed Central

    Dotu, Ivan; Garcia-Martin, Juan Antonio; Slinger, Betty L.; Mechery, Vinodh; Meyer, Michelle M.; Clote, Peter

    2014-01-01

    Nanotechnology and synthetic biology currently constitute one of the most innovative, interdisciplinary fields of research, poised to radically transform society in the 21st century. This paper concerns the synthetic design of ribonucleic acid molecules, using our recent algorithm, RNAiFold, which can determine all RNA sequences whose minimum free energy secondary structure is a user-specified target structure. Using RNAiFold, we design ten cis-cleaving hammerhead ribozymes, all of which are shown to be functional by a cleavage assay. We additionally use RNAiFold to design a functional cis-cleaving hammerhead as a modular unit of a synthetic larger RNA. Analysis of kinetics on this small set of hammerheads suggests that cleavage rate of computationally designed ribozymes may be correlated with positional entropy, ensemble defect, structural flexibility/rigidity and related measures. Artificial ribozymes have been designed in the past either manually or by SELEX (Systematic Evolution of Ligands by Exponential Enrichment); however, this appears to be the first purely computational design and experimental validation of novel functional ribozymes. RNAiFold is available at http://bioinformatics.bc.edu/clotelab/RNAiFold/. PMID:25209235

  14. Oak Ridge Environmental Information System (OREIS) functional system design document

    SciTech Connect

    Birchfield, T.E.; Brown, M.O.; Coleman, P.R.

    1994-03-01

    The OREIS Functional System Design document provides a detailed functional description of the Oak Ridge Environmental Information System (OREIS). It expands the system requirements defined in the OREIS Phase 1-System Definition Document (ES/ER/TM-34). Documentation of OREIS development is based on the Automated Data Processing System Development Methodology, a Martin Marietta Energy Systems, Inc., procedure written to assist in developing scientific and technical computer systems. This document focuses on the development of the functional design of the user interface, which includes the integration of commercial applications software. The data model and data dictionary are summarized briefly; however, the Data Management Plan for OREIS (ES/ER/TM-39), a companion document to the Functional System Design document, provides the complete data dictionary and detailed descriptions of the requirements for the data base structure. The OREIS system will provide the following functions, which are executed from a Menu Manager: (1) preferences, (2) view manager, (3) macro manager, (4) data analysis (assisted analysis and unassisted analysis), and (5) spatial analysis/map generation (assisted ARC/INFO and unassisted ARC/INFO). Additional functionality includes interprocess communications, which handle background operations of OREIS.

  15. Noncovalently functionalized multiwalled carbon nanotubes by chitosan-grafted reduced graphene oxide and their synergistic reinforcing effects in chitosan films.

    PubMed

    Pan, Yongzheng; Bao, Hongqian; Li, Lin

    2011-12-01

    Water-soluble chitosan-grafted reduced graphene oxide (CS-rGO) sheets are successfully synthesized via amidation reaction and chemical reduction. CS-rGO possesses not only remarkable graphitic property but also favorable water solubility, which is found to be able to effectively disperse multiwalled carbon nanotubes (MWCNTs) in acidic solutions via noncovalent interaction. The efficiency of CS-rGO in dispersing MWCNTs is tested to be higher than that of plain graphene oxide (GO) and a commercial surfactant, sodium dodecyl sulfate (SDS). With incorporation of 1 wt % CS-rGO dispersed MWCNTs (CS-rGO-MWCNTs), the tensile modulus, strength and toughness of the chitosan (CS) nanocomposites can be increased by 49, 114, and 193%, respectively. The reinforcing and toughening effects of CS-rGO-MWCNTs are much more prominent than those of single-component fillers, such as MWCNTs, GO, and CS-rGO. Noncovalent π-π interactions between graphene sheets and nanotubes and hydrogen bonds between grafted CS and the CS matrix are responsible for generating effective load transfer between CS-rGO-MWCNTs and the CS matrix, causing the simultaneously increased strength and toughness of the nanocomposites. PMID:22091530

  16. Engineering study for the functional design of a multiprocessor system

    NASA Technical Reports Server (NTRS)

    Miller, J. S.; Vandever, W. H.; Stanten, S. F.; Avakian, A. E.; Kosmala, A. L.

    1972-01-01

    The results are presented of a study to generate a functional system design of a multiprocessing computer system capable of satisfying the computational requirements of a space station. These data management system requirements were specified to include: (1) real time control, (2) data processing and storage, (3) data retrieval, and (4) remote terminal servicing.

  17. Investigation of Selectively-Reinforced Metallic Lugs

    NASA Technical Reports Server (NTRS)

    Farley, Gary L.; Abada, Christopher H.

    2007-01-01

    An investigation of the effects of material and geometric variables on the response of U-shaped band-reinforced metallic lugs was performed. Variables studied were reinforcement, adhesive and metallic lug mechanical properties, hole diameter, reinforcement and adhesive thickness, and the distance from the hole s center to the end of the lug. Generally, U-shaped band reinforced lugs exhibited superior performance than non-reinforced lugs, that is higher load at the conventional lug design criteria of four percent hole elongation. Depending upon the reinforcement configuration the increase in load may be negligible to 15 or 20 percent. U-shaped band reinforcement increases lug load carrying capability primarily through two mechanisms; increasing the slope of the response curve after the initial knee and restraining overall deformation of the metallic portion of the lug facilitating increased yielding of metallic material between the hole and the edge of the metallic portion of the lug.

  18. Functional Design in Rehabilitation: Modular Mechanisms for Ankle Complex

    PubMed Central

    2016-01-01

    This paper is aimed at presenting an innovative ankle rehabilitation device based on a parallel mechanism. A functional analysis and design are described to obtain a device able to guarantee ankle movement while patient's body remains stationary. Human ankle is a challenging context where a series of joints are highly integrated. The proposed rehabilitation device permits a patient with walking defects to improve his or her gait. The research focuses on plantar-flexion-dorsiflexion movement. The robust design starts from an accurate modelling of ankle movements during walking, assessing motion data from healthy individuals and patients. The kinematics analysis and functional evaluations lead the study and development of the articulated system. In particular, results of simulations support the effectiveness of the current design. A 3D prototype is presented highlighting that the ankle motion is successfully demonstrated. PMID:27524881

  19. Concept and design of a multiple-function laser (MFL)

    NASA Astrophysics Data System (ADS)

    Karning, Heinrich; Ruger, James F.; Weispfenning, Martin

    1998-10-01

    The multifunctional properties of modern Laser sources for future military sensor applications will be studied. The goal of this study is the design of a modular laser source which covers various functions like: Laser rangefinding. Target designation (1.06 micrometer), Eyesafe target designation (1.5 micrometer), Laser radar for Automatic target recognition, Identification friend or foe using Laser interrogation with D- band response as well as allowance for Covert communication and Missile jamming with a laser in the 3 to 5 micrometer range. It is obvious that these applications require a wide range of power levels, wavelength agility and pulse repetition rates. The concept for a compact Laser source to cover these requirements will be presented. In addition a concept for the integrated sensor to provide the above mentioned functions will also be presented.

  20. Reinforced Carbon Nanotubes.

    DOEpatents

    Ren, Zhifen; Wen, Jian Guo; Lao, Jing Y.; Li, Wenzhi

    2005-06-28

    The present invention relates generally to reinforced carbon nanotubes, and more particularly to reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  1. Vestibular Function Research (VFR) experiment. Phase B: Design definition study

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The Vestibular Functions Research (VFR) Experiment was established to investigate the neurosensory and related physiological processes believed to be associated with the space flight nausea syndrome and to develop logical means for its prediction, prevention and treatment. The VFR Project consists of ground and spaceflight experimentation using frogs as specimens. The phase B Preliminary Design Study provided for the preliminary design of the experiment hardware, preparation of performance and hardware specification and a Phase C/D development plan, establishment of STS (Space Transportation System) interfaces and mission operations, and the study of a variety of hardware, experiment and mission options. The study consist of three major tasks: (1) mission mode trade-off; (2) conceptual design; and (3) preliminary design.

  2. Token Reinforcement: A Review and Analysis

    ERIC Educational Resources Information Center

    Hackenberg, Timothy D.

    2009-01-01

    Token reinforcement procedures and concepts are reviewed and discussed in relation to general principles of behavior. The paper is divided into four main parts. Part I reviews and discusses previous research on token systems in relation to common behavioral functions--reinforcement, temporal organization, antecedent stimulus functions, and…

  3. Response deprivation, reinforcement, and economics

    PubMed Central

    Allison, James

    1993-01-01

    Reinforcement of an instrumental response results not from a special kind of response consequence known as a reinforcer, but from a special kind of schedule known as a response-deprivation schedule. Under the requirements of a response-deprivation schedule, the baseline rate of the instrumental response permits less than the baseline rate of the contingent response. Because reinforcement occurs only if the schedule deprives the organism of the contingent response, reinforcement cannot result from any intrinsic property of the contingent response or any property relative to the instrumental response. Two typical effects of response-deprivation schedules—facilitation of the instrumental response and suppression of the contingent response—are discussed in terms of economic concepts and models of instrumental performance. It is suggested that response deprivation makes the contingent response function as an economic good, the instrumental response as currency. PMID:16812695

  4. Biomimetic Scaffold Design for Functional and Integrative Tendon Repair

    PubMed Central

    Zhang, Xinzhi; Bogdanowicz, Danielle; Erisken, Cevat; Lee, Nancy M.; Lu, Helen H.

    2012-01-01

    Rotator cuff tears represent the most common shoulder injuries in the United States. The debilitating effect of this degenerative condition coupled with the high incidence of failure associated with existing graft choices underscore the clinical need for alternative grafting solutions. The two critical design criteria for the ideal tendon graft would require the graft to not only exhibit physiologically relevant mechanical properties but also be able to facilitate functional graft integration by promoting the regeneration of the native tendon-to-bone interface. Centered on these design goals, this review will highlight current approaches to functional and integrative tendon repair. In particular, the application of biomimetic design principles through the use of nanofiber- and nanocomposite-based scaffolds for tendon tissue engineering will be discussed. This review will begin with nanofiber-based approaches to functional tendon repair, followed by a section highlighting the exciting research on tendon-to-bone interface regeneration, with an emphasis on implementation of strategic biomimicry in nanofiber scaffold design and the concomitant formation of graded multi-tissue systems for integrative soft tissue repair. This review will conclude with a summary and future directions section. PMID:22244070

  5. Effect of reinforcement surface functionalization on the mechanical properties of nacre-like bulk lamellar composites processed by a hybrid conventional method.

    PubMed

    Gurbuz, Selen N; Dericioglu, Arcan F

    2013-05-01

    Alumina platelet reinforced epoxy matrix composites with an architecture resembling to natural nacre were fabricated by a hybrid conventional method called Hot-press Assisted Slip Casting process (HASC). Correlation between processing parameters, platelet content, platelet orientation and mechanical property enhancement of the fabricated composites was examined. In order to investigate the effect of interfacial compatibility and bonding on the mechanical properties of the fabricated inorganic-organic composites, platelet surfaces were modified with both epoxy- and amino-functional silanes. As received and functionalized platelet surfaces were studied by X-Ray Photoelectron Spectroscopy (XPS) to confirm the success of surface modification. Fabricated bio-inspired bulk lamellar composite materials were characterized in terms of their microstructural architecture and mechanical properties. The results obtained indicated that HASC processed composites exhibit enhanced flexural strength, stiffness and hardness, as compared to neat epoxy and composites fabricated by simple mixing, as a result of their nacre-like architecture with well aligned platelets. It has been also observed that functionalization by both type of silanes improves interfacial adhesion between platelets and epoxy matrix resulting in further enhancement of the mechanical properties of bulk lamellar composites fabricated by HASC. PMID:23498226

  6. Fiber-reinforced syntactic foams

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Jen

    Long fibers are generally preferred for reinforcing foams for performance reasons. However, uniform dispersion is difficult to achieve because they must be mixed with liquid resin prior to foam expansion. New approaches aiming to overcome such problem have been developed at USC's Composites Center. Fiber-reinforced syntactic foams with long fibers (over 6 mm in length) manufactured at USC's Composites Center have achieved promising mechanical properties and demonstrated lower density relative to conventional composite foams. Fiber-reinforced syntactic foams were synthesized from thermosetting polymeric microspheres (amino and phenolic microspheres), as well as thermoplastic PVC heat expandable microspheres (HEMs). Carbon and/or aramid fibers were used to reinforce the syntactic foams. Basic mechanical properties, including shear, tensile, and compression, were measured in syntactic foams and fiber-reinforced syntactic foams. Microstructure and crack propagation behavior were investigated by scanning electron microscope and light microscopy. Failure mechanisms and reinforcing mechanisms of fiber-reinforced syntactic foams were also analyzed. As expected, additions of fiber reinforcements to foams enhanced both tensile and shear properties. However, only limited enhancement in compression properties was observed, and fiber reinforcement was of limited benefit in this regard. Therefore, a hybrid foam design was explored and evaluated in an attempt to enhance compression properties. HEMs were blended with glass microspheres to produce hybrid foams, and hybrid foams were subsequently reinforced with continuous aramid fibers to produce fiber-reinforced hybrid foams. Mechanical properties of these foams were evaluated. Findings indicated that the production of hybrid foams was an effective way to enhance the compressive properties of syntactic foams, while the addition of fiber reinforcements enhanced the shear and tensile performance of syntactic foams. Another approach

  7. Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

    NASA Astrophysics Data System (ADS)

    Ovitigala, Thilan

    The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams

  8. Motif-directed flexible backbone design of functional interactions

    PubMed Central

    Havranek, James J; Baker, David

    2009-01-01

    Computational protein design relies on a number of approximations to efficiently search the huge sequence space available to proteins. The fixed backbone and rotamer approximations in particular are important for formulating protein design as a discrete combinatorial optimization problem. However, the resulting coarse-grained sampling of possible side-chain terminal positions is problematic for the design of protein function, which depends on precise positioning of side-chain atoms. Although backbone flexibility can greatly increase the conformation freedom of side-chain functional groups, it is not obvious which backbone movements will generate the critical constellation of atoms responsible for protein function. Here, we report an automated method for identifying protein backbone movements that can give rise to any specified set of desired side-chain atomic placements and interactions, using protein–DNA interfaces as a model system. We use a library of previously observed protein–DNA interactions (motifs) and a rotamer-based description of side-chain conformation freedom to identify placements for the protein backbone that can give rise to a favorable side-chain interaction with DNA. We describe a tree-search algorithm for identifying those combinations of interactions from the library that can be realized with minimal perturbation of the protein backbone. We compare the efficiency of this method with the alternative approach of building and screening alternate backbone conformations. PMID:19472357

  9. HAL/SM system functional design specification. [systems analysis and design analysis of central processing units

    NASA Technical Reports Server (NTRS)

    Ross, C.; Williams, G. P. W., Jr.

    1975-01-01

    The functional design of a preprocessor, and subsystems is described. A structure chart and a data flow diagram are included for each subsystem. Also a group of intermodule interface definitions (one definition per module) is included immediately following the structure chart and data flow for a particular subsystem. Each of these intermodule interface definitions consists of the identification of the module, the function the module is to perform, the identification and definition of parameter interfaces to the module, and any design notes associated with the module. Also described are compilers and computer libraries.

  10. Conditioned Reinforcement Value and Resistance to Change

    PubMed Central

    Shahan, Timothy A; Podlesnik, Christopher A

    2008-01-01

    Three experiments examined the effects of conditioned reinforcement value and primary reinforcement rate on resistance to change using a multiple schedule of observing-response procedures with pigeons. In the absence of observing responses in both components, unsignaled periods of variable-interval (VI) schedule food reinforcement alternated with extinction. Observing responses in both components intermittently produced 15 s of a stimulus associated with the VI schedule (i.e., S+). In the first experiment, a lower-valued conditioned reinforcer and a higher rate of primary reinforcement were arranged in one component by adding response-independent food deliveries uncorrelated with S+. In the second experiment, one component arranged a lower valued conditioned reinforcer but a higher rate of primary reinforcement by increasing the probability of VI schedule periods relative to extinction periods. In the third experiment, the two observing-response components provided similar rates of primary reinforcement but arranged different valued conditioned reinforcers. Across the three experiments, observing-response rates were typically higher in the component associated with the higher valued conditioned reinforcer. Resistance to change was not affected by conditioned reinforcement value, but was an orderly function of the rate of primary reinforcement obtained in the two components. One interpretation of these results is that S+ value does not affect response strength and that S+ deliveries increase response rates through a mechanism other than reinforcement. Alternatively, because resistance to change depends on the discriminative stimulus–reinforcer relation, the failure of S+ value to impact resistance to change could have resulted from a lack of transfer of S+ value to the broader discriminative context. PMID:18540215

  11. Design of multi-function Hanford tank corrosion monitoring system

    SciTech Connect

    EDGEMON, G.L.

    1999-04-01

    A multi-fiction corrosion monitoring system has been designed for installation into DST 241-AN-105 at the Hanford Site in fiscal year 1999. The 241-AN-105 system is the third-generation corrosion monitoring system described by TTP RLO-8-WT-21. Improvements and upgrades from the second-generation system (installed in 241-AN-102) that have been incorporated into the third-generation system include: Gasket seating surfaces utilize O-rings instead of a washer type gasket for improved seal; Probe design contains an equally spaced array of 22 thermocouples; Probe design contains an adjustable verification thermocouple; Probe design contains three ports for pressure/gas sampling; Probe design contains one set of strain gauges to monitor probe flexure if flexure occurs; Probe utilizes an adjustable collar to allow depth adjustment of probe during installation; System is capable of periodically conducting LPR scans; System is housed in a climate controlled enclosure adjacent to the riser containing the probe; System uses wireless Ethernet links to send data to Hanford Local Area Network; System uses commercial remote access software to allow remote command and control; and Above ground wiring uses driven shields to reduce external electrostatic noise in the data. These new design features have transformed what was primarily a second-generation corrosion monitoring system into a multi-function tank monitoring system that adds a great deal of functionality to the probe, provides for a better understanding of the relationship between corrosion and other tank operating parameters, and optimizes the use of the riser that houses the probe in the tank.

  12. The fabrication and tribological behavior of epoxy composites modified by the three-dimensional polyurethane sponge reinforced with dopamine functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Wang, Huaiyuan; Sun, Liyuan; Wang, Enqun; Zhu, Yixing; Zhu, Yanji

    2016-01-01

    Three-dimensional (3D) interpenetrating network structure epoxy composites were fabricated based on the modified carbon nanotube (CNT) reinforced flexible polyurethane (PU) sponge. CNTs were first functionalized with polydopamine (PDA) as revealed by TEM imaging, which is formed via the oxidative self-polymerization of dopamine. Then the functionalized CNTs (CNT-PDA) were successfully anchored on the skeleton surfaces of sponge, forming a continuous 3D carbon network. The interfacial interaction between modified PU sponge and epoxy (EP) matrix was significantly enhanced due to the covalent linkage of PDA. Improvement in the thermal stability of CNT-PDA/PU3D/EP composites was observed by TG analysis and related to the CNTs anchored on the skeleton of sponge. The tribological properties of pure EP, PU3D/EP and CNT-PDA/PU3D/EP composites were comparatively investigated in terms of different loads and velocities. Results demonstrated that CNT-PDA/PU3D/EP composites exhibited the best tribological performance owing to the strong interfacial interaction and the 3D carbon network structure. In particular, the wear resistance of CNT-PDA/PU3D/EP composites was 6.2 times and 3 times higher than those of pure EP and PU3D/EP composites under the applied load of 1.6 MPa, respectively.

  13. Functionalization of biomineral reinforcement in crustacean cuticle: Calcite orientation in the partes incisivae of the mandibles of Porcellio scaber and the supralittoral species Tylos europaeus (Oniscidea, Isopoda).

    PubMed

    Huber, Julia; Griesshaber, Erika; Nindiyasari, Fitriana; Schmahl, Wolfgang W; Ziegler, Andreas

    2015-05-01

    In arthropods the cuticle forms an exoskeleton with its physical and chemical properties adapted to functions of distinct skeletal elements. The cuticle of the partes incisivae (PI) in mandibles of terrestrial isopods is a composite of chitin-protein fibrils/fibres and minerals. It consists of an unmineralized tip, a middle region with organic fibrils reinforced mainly with amorphous calcium phosphate and a base region mineralized with amorphous calcium carbonate and calcite. In this study we extend our work on the structure and material properties of the incisive cuticle employing electron backscatter diffraction (EBSD), and investigate calcite orientation patterns in the PI of two terrestrial isopod species from different habitats. We trace small-scale differences in texture sharpness and calcite microstructure, and compare calcite organization and orientation patterns in the PI with those in the tergites of the same isopod species. We observe that in the PI calcite orientation, the degree of crystal alignment, and mode of crystalline domain assemblage is highly varied within short length scales. This contrasts to calcite organization in the tergite cuticle, where calcite has only one specific texture pattern. Such a large range in the variation of calcite organization has not been observed in other carbonate biological hard tissues, such as shells and teeth, where one specific texture and microstructure prevails. Thus, the investigated isopod species are able to control crystallization of the amorphous carbonate precursor in a differential way, most probably related to the function of the individual skeletal element and the animals' behavior. PMID:25818510

  14. Evaluating the integrity of the reinforced concrete structure repaired by epoxy injection using simulated transfer function of impact-echo response

    SciTech Connect

    Cheng, Chia-Chi; Yu, Chih-peng; Wu, Jiunn-Hong; Hsu, Keng-Tsan; Ke, Ying-Tsu

    2014-02-18

    Cracks and honeycombs are often found inside reinforced concrete (RC) structure caused by excessive external force, or improper casting of concrete. The repairing method usually involves epoxy injection. The impact-echo method, which is a sensitive for detecting of the interior voids, may not be applicable to assess the integrity of the repaired member as both air and epoxy are less in acoustic impedances. In this study, the repaired RC structure was evaluated by the simulated transfer function of the IE displacement waveform where the R-wave displacement waveform is used as a base of a simulated force-time function. The effect of different thickness of the epoxy layer to the amplitude corresponding to the interface is studied by testing on specimen containing repaired naturally delaminated cracks with crack widths about 1 mm, 3 mm and 5 mm. The impact-echo responses were compared with the drilling cores at the test positions. The results showed the cracks were not fully filled with epoxy when the peak amplitude corresponding to the interface dropped less than 20%. The peak corresponding to the thicker epoxy layer tends to be larger in amplitude. A field study was also performed on a column damaged by earthquake before and after repairing.

  15. Mechanical properties of epoxy nanocomposites reinforced with very low content of amino-functionalized single-walled carbon nanotubes.

    PubMed

    Zhao, Yun; Mannhalter, Bert; Hong, Haiping; Welsh, Jeffry S

    2010-09-01

    Functionalized single-walled carbon nanotubes (SWNTs) with amino groups were prepared by oxidation, acylation, and amidation of SWNT surfaces. Epoxy/SWNT composite membranes were fabricated using a very low content of amino-grafted SWNTs (< or = 0.08 wt%) as fillers. SWNTs with amino groups acted as a curing agent, covalently bonding to the epoxy matrix. The influence of SWNT content on the mechanical properties of epoxy/amino-functionalized SWNT composite membrane was investigated. It is found that the tensile strength of composites is enhanced with the increase of SWNTs. Only 0.01 wt% of SWNT-R-NH, leads to improvement of the epoxy tensile strength by 9.5%, and 0.08 wt% of SWNT-R-NH2 increased tensile strength by 13.6%. For comparison purposes, epoxy/pristine-SWNT films were also prepared. The improvement of the tensile strength of the amino-functionalized SWNTs system is more remarkable than that of pristine SWNT system at very low weight-percentage loading. The amino groups on the surface of SWNTs can be covalently attached to the epoxy matrix, which effectively improves the dispersion and adhesion of SWNTs in epoxy. This leads to the enhancement in mechanical properties of the epoxy composite. Mechanical results between functionalized and pristine nanotubes are discussed in detail. PMID:21133104

  16. Ensemble algorithms in reinforcement learning.

    PubMed

    Wiering, Marco A; van Hasselt, Hado

    2008-08-01

    This paper describes several ensemble methods that combine multiple different reinforcement learning (RL) algorithms in a single agent. The aim is to enhance learning speed and final performance by combining the chosen actions or action probabilities of different RL algorithms. We designed and implemented four different ensemble methods combining the following five different RL algorithms: Q-learning, Sarsa, actor-critic (AC), QV-learning, and AC learning automaton. The intuitively designed ensemble methods, namely, majority voting (MV), rank voting, Boltzmann multiplication (BM), and Boltzmann addition, combine the policies derived from the value functions of the different RL algorithms, in contrast to previous work where ensemble methods have been used in RL for representing and learning a single value function. We show experiments on five maze problems of varying complexity; the first problem is simple, but the other four maze tasks are of a dynamic or partially observable nature. The results indicate that the BM and MV ensembles significantly outperform the single RL algorithms. PMID:18632380

  17. Matching and Conditioned Reinforcement Rate

    PubMed Central

    Shahan, Timothy A; Podlesnik, Christopher A; Jimenez-Gomez, Corina

    2006-01-01

    Attempts to examine the effects of variations in relative conditioned reinforcement rate on choice have been confounded by changes in rates of primary reinforcement or changes in the value of the conditioned reinforcer. To avoid these problems, this experiment used concurrent observing responses to examine sensitivity of choice to relative conditioned reinforcement rate. In the absence of observing responses, unsignaled periods of food delivery on a variable-interval 90-s schedule alternated with extinction on a center key (i.e., a mixed schedule was in effect). Two concurrently available observing responses produced 15-s access to a stimulus differentially associated with the schedule of food delivery (S+). The relative rate of S+ deliveries arranged by independent variable-interval schedules for the two observing responses varied across conditions. The relation between the ratio of observing responses and the ratio of S+ deliveries was well described by the generalized matching law, despite the absence of changes in the rate of food delivery. In addition, the value of the S+ deliveries likely remained constant across conditions because the ratio of S+ to mixed schedule food deliveries remained constant. Assuming that S+ deliveries serve as conditioned reinforcers, these findings are consistent with the functional similarity between primary and conditioned reinforcers suggested by general choice theories based on the concatenated matching law (e.g., contextual choice and hyperbolic value-added models). These findings are inconsistent with delay reduction theory, which has no terms for the effects of rate of conditioned reinforcement in the absence of changes in rate of primary reinforcement. PMID:16673824

  18. Optimum weight design of functionally graded material gears

    NASA Astrophysics Data System (ADS)

    Jing, Shikai; Zhang, He; Zhou, Jingtao; Song, Guohua

    2015-11-01

    Traditional gear weight optimization methods consider gear tooth number, module, face width or other dimension parameters of gear as design variables. However, due to the complicated form and geometric features peculiar to the gear, there will be large amounts of design parameters in gear design, and the influences of gear parameters changing on gear trains, transmission system and the whole equipment have to be taken into account, which increases the complexity of optimization problem. This paper puts forward to apply functionally graded materials (FGMs) to gears and then conduct the optimization. According to the force situation of gears, the material distribution form of FGM gears is determined. Then based on the performance parameters analysis of FGMs and the practical working demands for gears, a multi-objective optimization model is formed. Finally by using the goal driven optimization (GDO) method, the optimal material distribution is achieved, which makes gear weight and the maximum deformation be minimum and the maximum bending stress do not exceed the allowable stress. As an example, the applying of FGM to automotive transmission gear is conducted to illustrate the optimization design process and the result shows that under the condition of keeping the normal working performance of gear, the method achieves in greatly reducing the gear weight. This research proposes a FGM gears design method that is able to largely reduce the weight of gears by optimizing the microscopic material parameters instead of changing the macroscopic dimension parameters of gears, which reduces the complexity of gear weight optimization problem.

  19. Functionalization of multiwalled carbon nanotubes for reinforcing of poly( L-lactide-co-ɛ-caprolactone) biodegradable copolymers

    NASA Astrophysics Data System (ADS)

    Chakoli, Ali Nabipour; Wan, Jing; Feng, Jiang Tao; Amirian, Maryam; Sui, Jie He; Cai, Wei

    2009-10-01

    Up to now, synthetic polymers and biomacromolecules have been grafted or assembled onto the convex surface of carbon nanotubes (CNTs) via covalent bonds or chemisorptions. In this research, poly( L-lactide-co-ɛ-caprolactone)-functionalized multiwalled carbon nanotubes (MWCNT-OH- g-PCLA)s are synthesized by in situ ring-opening copolymerization of L-lactide (LA) and ɛ-caprolactone (CL) using stannous octanoate and hydroxylated MWCNTs (MWCNT-OHs) as the initiating system. The pristine MWCNTs are modified to possess carboxyl groups and then hydroxyl groups. MWCNT-OHs are used as coinitiators to polymerize LA and CL by the surface-initiated ring-opening polymerization. The FT-IR spectra, SEM and TEM micrographs revealed that the PCLA grafted form the sidewall of MWCNTs strongly. The TGA analysis indicates that about 75 wt% of functionalized MWCNTs with PCLA belongs to grafted PCLA and the remaining 25 wt% to the initial MWCNT-OH.

  20. Design strategies of sea urchin teeth: structure, composition and micromechanical relations to function.

    PubMed Central

    Wang, R Z; Addadi, L; Weiner, S

    1997-01-01

    The teeth of sea urchins comprise a variety of different structural entities, all of which are composed of magnesium-bearing calcite together with a small amount of organic material. The teeth are worn down continuously, but in such a way that they remain sharp and functional. Here we describe aspects of the structural, compositional and micromechanical properties of the teeth of Paracentrotus lividus using scanning electron microscopy, infrared spectrometry, atomic absorption. X-ray diffraction and microindentation. The S-shaped single crystalline calcitic fibres are one of the main structural elements of the tooth. They extend from the stone part to the keel. The diameter of the fibres increases gradually from less than 1 micron at the stone tip to about 20 microns at the keel end, while their MgCO3 contents decrease from about 13 mol% to about 4.5 mol%. Each fibre is coated by a thin organic sheath and surrounded by polycrystalline calcitic discs containing as much as 35 mol% MgCO3. This structure constitutes a unique kind of gradient fibre-reinforced ceramic matrix composite, whose microhardness and toughness decrease gradually from the stone part to the keel. Primary plates are also important structural elements of the tooth. Each primary plate has a very unusual sandwich-like structure with a calcitic envelope surrounding a thin apparently amorphous CaCO3 layer. This central layer, together with the primary plate/disc interface, improves the toughness of this zone by stopping and blunting cracks. The self-sharpening function of the teeth is believed to result from the combination of the geometrical shape of the main structural elements and their spatial arrangement, the interfacial strength between structural elements, and the hardness gradient extending from the working stone part to the surrounding zones. The sea urchin tooth structure possesses an array of interesting functional design features, some of which may possibly be applicable to materials science

  1. Effective Design of Multifunctional Peptides by Combining Compatible Functions

    PubMed Central

    Diener, Christian; Garza Ramos Martínez, Georgina; Moreno Blas, Daniel; Castillo González, David A.; Corzo, Gerardo; Castro-Obregon, Susana; Del Rio, Gabriel

    2016-01-01

    Multifunctionality is a common trait of many natural proteins and peptides, yet the rules to generate such multifunctionality remain unclear. We propose that the rules defining some protein/peptide functions are compatible. To explore this hypothesis, we trained a computational method to predict cell-penetrating peptides at the sequence level and learned that antimicrobial peptides and DNA-binding proteins are compatible with the rules of our predictor. Based on this finding, we expected that designing peptides for CPP activity may render AMP and DNA-binding activities. To test this prediction, we designed peptides that embedded two independent functional domains (nuclear localization and yeast pheromone activity), linked by optimizing their composition to fit the rules characterizing cell-penetrating peptides. These peptides presented effective cell penetration, DNA-binding, pheromone and antimicrobial activities, thus confirming the effectiveness of our computational approach to design multifunctional peptides with potential therapeutic uses. Our computational implementation is available at http://bis.ifc.unam.mx/en/software/dcf. PMID:27096600

  2. Batch Mode Reinforcement Learning based on the Synthesis of Artificial Trajectories.

    PubMed

    Fonteneau, Raphael; Murphy, Susan A; Wehenkel, Louis; Ernst, Damien

    2013-09-01

    In this paper, we consider the batch mode reinforcement learning setting, where the central problem is to learn from a sample of trajectories a policy that satisfies or optimizes a performance criterion. We focus on the continuous state space case for which usual resolution schemes rely on function approximators either to represent the underlying control problem or to represent its value function. As an alternative to the use of function approximators, we rely on the synthesis of "artificial trajectories" from the given sample of trajectories, and show that this idea opens new avenues for designing and analyzing algorithms for batch mode reinforcement learning. PMID:24049244

  3. Batch Mode Reinforcement Learning based on the Synthesis of Artificial Trajectories

    PubMed Central

    Fonteneau, Raphael; Murphy, Susan A.; Wehenkel, Louis; Ernst, Damien

    2013-01-01

    In this paper, we consider the batch mode reinforcement learning setting, where the central problem is to learn from a sample of trajectories a policy that satisfies or optimizes a performance criterion. We focus on the continuous state space case for which usual resolution schemes rely on function approximators either to represent the underlying control problem or to represent its value function. As an alternative to the use of function approximators, we rely on the synthesis of “artificial trajectories” from the given sample of trajectories, and show that this idea opens new avenues for designing and analyzing algorithms for batch mode reinforcement learning. PMID:24049244

  4. ATRP in the design of functional materials for biomedical applications

    PubMed Central

    Siegwart, Daniel J.; Oh, Jung Kwon; Matyjaszewski, Krzysztof

    2013-01-01

    Atom Transfer Radical Polymerization (ATRP) is an effective technique for the design and preparation of multifunctional, nanostructured materials for a variety of applications in biology and medicine. ATRP enables precise control over macromolecular structure, order, and functionality, which are important considerations for emerging biomedical designs. This article reviews recent advances in the preparation of polymer-based nanomaterials using ATRP, including polymer bioconjugates, block copolymer-based drug delivery systems, cross-linked microgels/nanogels, diagnostic and imaging platforms, tissue engineering hydrogels, and degradable polymers. It is envisioned that precise engineering at the molecular level will translate to tailored macroscopic physical properties, thus enabling control of the key elements for realized biomedical applications. PMID:23525884

  5. DNA from natural sources in design of functional devices.

    PubMed

    Hung, Yu-Chueh; Bauer, Dennis M; Ahmed, Ishtiaq; Fruk, Ljiljana

    2014-05-15

    The role of DNA as structuring or templating agent has become more significant with the development of nanobiotechnology. Although short single and double stranded DNA have extensively been used as immobilization tool, as a template for nanoparticle preparation and in design of various devices such as nanomotors and biosensors, DNA from natural sources has an advantage of being abundant, cheap and readily available. Therefore, it is not surprising that there is a huge interest in making the use of natural DNA properties for both nano- and micro-applications. In this review we attempt to give an overview of the up to date applications of natural DNA, either from viral, marine or mammalian sources, in design of functional devices. This article is meant to be a starting point and a guide to the platforms in which natural DNA is employed such as DNA origami, optoelectronic devices and organic catalysis. PMID:24631889

  6. Optimizing experimental design for comparing models of brain function.

    PubMed

    Daunizeau, Jean; Preuschoff, Kerstin; Friston, Karl; Stephan, Klaas

    2011-11-01

    This article presents the first attempt to formalize the optimization of experimental design with the aim of comparing models of brain function based on neuroimaging data. We demonstrate our approach in the context of Dynamic Causal Modelling (DCM), which relates experimental manipulations to observed network dynamics (via hidden neuronal states) and provides an inference framework for selecting among candidate models. Here, we show how to optimize the sensitivity of model selection by choosing among experimental designs according to their respective model selection accuracy. Using Bayesian decision theory, we (i) derive the Laplace-Chernoff risk for model selection, (ii) disclose its relationship with classical design optimality criteria and (iii) assess its sensitivity to basic modelling assumptions. We then evaluate the approach when identifying brain networks using DCM. Monte-Carlo simulations and empirical analyses of fMRI data from a simple bimanual motor task in humans serve to demonstrate the relationship between network identification and the optimal experimental design. For example, we show that deciding whether there is a feedback connection requires shorter epoch durations, relative to asking whether there is experimentally induced change in a connection that is known to be present. Finally, we discuss limitations and potential extensions of this work. PMID:22125485

  7. Functional and aesthetic approach to design of bird feeders

    NASA Astrophysics Data System (ADS)

    Kukhta, A.; Kukhta, M.

    2015-10-01

    Anthropogenic objects which load the urban environment negatively affects the human psyche. The alternative is attracting elements of the natural environment into urban environment, of which some of the most frequently identified are birds. Attracting birds in the city is possible by means of feeders and artificial nests, however, both must be harmonious. The aim of this study is to analyze the essential functions of the feeders, and their integration into the environmental design and development of the city. On this basis an original feeder which is convenient for use by birds and attracts people's attention is developed. In this paper we apply comparative analysis of different types of feeders encountered in Tomsk, bird watching, and evaluate usability of different types of feeders from the position of their convenience both for birds and human beings. Historical-cultural analysis for determining features of the architectural and environmental design of Tomsk is carried out, the method allows us to solve engineering problems. In this study the feeder convenient for bird use is designed which blends harmoniously with the architectural design of Tomsk.

  8. Rational design of functional and tunable oscillating enzymatic networks

    NASA Astrophysics Data System (ADS)

    Semenov, Sergey N.; Wong, Albert S. Y.; van der Made, R. Martijn; Postma, Sjoerd G. J.; Groen, Joost; van Roekel, Hendrik W. H.; de Greef, Tom F. A.; Huck, Wilhelm T. S.

    2015-02-01

    Life is sustained by complex systems operating far from equilibrium and consisting of a multitude of enzymatic reaction networks. The operating principles of biology's regulatory networks are known, but the in vitro assembly of out-of-equilibrium enzymatic reaction networks has proved challenging, limiting the development of synthetic systems showing autonomous behaviour. Here, we present a strategy for the rational design of programmable functional reaction networks that exhibit dynamic behaviour. We demonstrate that a network built around autoactivation and delayed negative feedback of the enzyme trypsin is capable of producing sustained oscillating concentrations of active trypsin for over 65 h. Other functions, such as amplification, analog-to-digital conversion and periodic control over equilibrium systems, are obtained by linking multiple network modules in microfluidic flow reactors. The methodology developed here provides a general framework to construct dissipative, tunable and robust (bio)chemical reaction networks.

  9. Rational design of functional and tunable oscillating enzymatic networks.

    PubMed

    Semenov, Sergey N; Wong, Albert S Y; van der Made, R Martijn; Postma, Sjoerd G J; Groen, Joost; van Roekel, Hendrik W H; de Greef, Tom F A; Huck, Wilhelm T S

    2015-02-01

    Life is sustained by complex systems operating far from equilibrium and consisting of a multitude of enzymatic reaction networks. The operating principles of biology's regulatory networks are known, but the in vitro assembly of out-of-equilibrium enzymatic reaction networks has proved challenging, limiting the development of synthetic systems showing autonomous behaviour. Here, we present a strategy for the rational design of programmable functional reaction networks that exhibit dynamic behaviour. We demonstrate that a network built around autoactivation and delayed negative feedback of the enzyme trypsin is capable of producing sustained oscillating concentrations of active trypsin for over 65 h. Other functions, such as amplification, analog-to-digital conversion and periodic control over equilibrium systems, are obtained by linking multiple network modules in microfluidic flow reactors. The methodology developed here provides a general framework to construct dissipative, tunable and robust (bio)chemical reaction networks. PMID:25615670

  10. Epoxy elastomers reinforced with functionalized multi-walled carbon nanotubes as stimuli-responsive shape memory materials

    SciTech Connect

    Lama, G. C.; Nasti, G.; Cerruti, P.; Gentile, G.; Carfagna, C.; Ambrogi, V.

    2014-05-15

    In this work, the incorporation of multiwalled carbon nanotubes (MWCNT) into epoxy-based elastomers was carried out in order to obtain nanocomposite systems with shape memory effect. For the preparation of elastomeric matrices, p-bis(2,3-epoxypropoxy)-α-methylstilbene (DOMS) was cured with sebacic acid. DOMS was synthesized in our laboratory and it is characterized by a rigid-rod, potentially liquid crystalline structure. A lightly cross-linked liquid crystalline elastomer was obtained. As for nanocomposites, variable amounts (0.75, 1.50, 3.0, 6.0, 12.0 wt.%) of COOH-MWCNTs were employed. In order to improve the nanotubes dispersibility and the interfacial adhesion with the epoxy matrix, an optimized two-step procedure was developed, which consisted in grafting the epoxy monomer onto the nanotube surface and then curing it in presence of crosslinking agent. DOMS-functionalized MWCNT were characterized through solvent dispersion experiments, FTIR spectroscopy and TGA analysis, which demonstrated the occurred covalent functionalization of the nanotubes with the epoxy monomers. The morphological analysis through electron microscopy demonstrated that this was an efficient strategy to improve the dispersion of nanotubes within the matrix. The second part of the work was devoted to the structural, thermal, mechanical and electric characterization of elastomeric nanocomposites. The results indicated a general improvement of properties of nanocomposites. Also, independently of the nanotube content, a smectic phase formed. Shape memory features of LC systems were also evaluated. It was demonstrated the shape could be recovered through heating, solvent immersion, as well as upon the application of an electrical field.