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Sample records for adaptive shape parameters

  1. Hopfield network with constraint parameter adaptation for overlapped shape recognition.

    PubMed

    Suganthan, P N; Teoh, E K; Mital, D P

    1999-01-01

    In this paper, we propose an energy formulation for homomorphic graph matching by the Hopfield network and a Lyapunov indirect method-based learning approach to adaptively learn the constraint parameter in the energy function. The adaptation scheme eliminates the need to specify the constraint parameter empirically and generates valid and better quality mappings than the analog Hopfield network with a fixed constraint parameter. The proposed Hopfield network with constraint parameter adaptation is applied to match silhouette images of keys and results are presented. PMID:18252543

  2. Active vibration control of Flexible Joint Manipulator using Input Shaping and Adaptive Parameter Auto Disturbance Rejection Controller

    NASA Astrophysics Data System (ADS)

    Li, W. P.; Luo, B.; Huang, H.

    2016-02-01

    This paper presents a vibration control strategy for a two-link Flexible Joint Manipulator (FJM) with a Hexapod Active Manipulator (HAM). A dynamic model of the multi-body, rigid-flexible system composed of an FJM, a HAM and a spacecraft was built. A hybrid controller was proposed by combining the Input Shaping (IS) technique with an Adaptive-Parameter Auto Disturbance Rejection Controller (APADRC). The controller was used to suppress the vibration caused by external disturbances and input motions. Parameters of the APADRC were adaptively adjusted to ensure the characteristic of the closed loop system to be a given reference system, even if the configuration of the manipulator significantly changes during motion. Because precise parameters of the flexible manipulator are not required in the IS system, the operation of the controller was sufficiently robust to accommodate uncertainties in system parameters. Simulations results verified the effectiveness of the HAM scheme and controller in the vibration suppression of FJM during operation.

  3. Shape optimization including finite element grid adaptation

    NASA Technical Reports Server (NTRS)

    Kikuchi, N.; Taylor, J. E.

    1984-01-01

    The prediction of optimal shape design for structures depends on having a sufficient level of precision in the computation of structural response. These requirements become critical in situations where the region to be designed includes stress concentrations or unilateral contact surfaces, for example. In the approach to shape optimization discussed here, a means to obtain grid adaptation is incorporated into the finite element procedures. This facility makes it possible to maintain a level of quality in the computational estimate of response that is surely adequate for the shape design problem.

  4. Self-adaptive parameters in genetic algorithms

    NASA Astrophysics Data System (ADS)

    Pellerin, Eric; Pigeon, Luc; Delisle, Sylvain

    2004-04-01

    Genetic algorithms are powerful search algorithms that can be applied to a wide range of problems. Generally, parameter setting is accomplished prior to running a Genetic Algorithm (GA) and this setting remains unchanged during execution. The problem of interest to us here is the self-adaptive parameters adjustment of a GA. In this research, we propose an approach in which the control of a genetic algorithm"s parameters can be encoded within the chromosome of each individual. The parameters" values are entirely dependent on the evolution mechanism and on the problem context. Our preliminary results show that a GA is able to learn and evaluate the quality of self-set parameters according to their degree of contribution to the resolution of the problem. These results are indicative of a promising approach to the development of GAs with self-adaptive parameter settings that do not require the user to pre-adjust parameters at the outset.

  5. Rapid estimation of high-parameter auditory-filter shapes

    PubMed Central

    Shen, Yi; Sivakumar, Rajeswari; Richards, Virginia M.

    2014-01-01

    A Bayesian adaptive procedure, the quick-auditory-filter (qAF) procedure, was used to estimate auditory-filter shapes that were asymmetric about their peaks. In three experiments, listeners who were naive to psychoacoustic experiments detected a fixed-level, pure-tone target presented with a spectrally notched noise masker. The qAF procedure adaptively manipulated the masker spectrum level and the position of the masker notch, which was optimized for the efficient estimation of the five parameters of an auditory-filter model. Experiment I demonstrated that the qAF procedure provided a convergent estimate of the auditory-filter shape at 2 kHz within 150 to 200 trials (approximately 15 min to complete) and, for a majority of listeners, excellent test-retest reliability. In experiment II, asymmetric auditory filters were estimated for target frequencies of 1 and 4 kHz and target levels of 30 and 50 dB sound pressure level. The estimated filter shapes were generally consistent with published norms, especially at the low target level. It is known that the auditory-filter estimates are narrower for forward masking than simultaneous masking due to peripheral suppression, a result replicated in experiment III using fewer than 200 qAF trials. PMID:25324086

  6. Rapid estimation of high-parameter auditory-filter shapes.

    PubMed

    Shen, Yi; Sivakumar, Rajeswari; Richards, Virginia M

    2014-10-01

    A Bayesian adaptive procedure, the quick-auditory-filter (qAF) procedure, was used to estimate auditory-filter shapes that were asymmetric about their peaks. In three experiments, listeners who were naive to psychoacoustic experiments detected a fixed-level, pure-tone target presented with a spectrally notched noise masker. The qAF procedure adaptively manipulated the masker spectrum level and the position of the masker notch, which was optimized for the efficient estimation of the five parameters of an auditory-filter model. Experiment I demonstrated that the qAF procedure provided a convergent estimate of the auditory-filter shape at 2 kHz within 150 to 200 trials (approximately 15 min to complete) and, for a majority of listeners, excellent test-retest reliability. In experiment II, asymmetric auditory filters were estimated for target frequencies of 1 and 4 kHz and target levels of 30 and 50 dB sound pressure level. The estimated filter shapes were generally consistent with published norms, especially at the low target level. It is known that the auditory-filter estimates are narrower for forward masking than simultaneous masking due to peripheral suppression, a result replicated in experiment III using fewer than 200 qAF trials. PMID:25324086

  7. Low Temperature Shape Memory Alloys for Adaptive, Autonomous Systems Project

    NASA Technical Reports Server (NTRS)

    Falker, John; Zeitlin, Nancy; Williams, Martha; Benafan, Othmane; Fesmire, James

    2015-01-01

    The objective of this joint activity between Kennedy Space Center (KSC) and Glenn Research Center (GRC) is to develop and evaluate the applicability of 2-way SMAs in proof-of-concept, low-temperature adaptive autonomous systems. As part of this low technology readiness (TRL) activity, we will develop and train low-temperature novel, 2-way shape memory alloys (SMAs) with actuation temperatures ranging from 0 C to 150 C. These experimental alloys will also be preliminary tested to evaluate their performance parameters and transformation (actuation) temperatures in low- temperature or cryogenic adaptive proof-of-concept systems. The challenge will be in the development, design, and training of the alloys for 2-way actuation at those temperatures.

  8. An Adaptable Metric Shapes Perceptual Space.

    PubMed

    Hisakata, Rumi; Nishida, Shin'ya; Johnston, Alan

    2016-07-25

    How do we derive a sense of the separation of points in the world within a space-variant visual system? Visual directions are thought to be coded directly by a process referred to as local sign, in which a neuron acts as a labeled line for the perceived direction associated with its activation [1, 2]. The separations of visual directions, however, are not given, nor are they directly related to the separations of signals on the receptive surface or in the brain, which are modified by retinal and cortical magnification, respectively [3]. To represent the separation of directions veridically, the corresponding neural signals need to be scaled in some way. We considered this scaling process may be influenced by adaptation. Here, we describe a novel adaptation paradigm, which can alter both apparent spatial separation and size. We measured the perceived separation of two dots and the size of geometric figures after adaptation to random dot patterns. We show that adapting to high-density texture not only increases the apparent sparseness (average element separation) of a lower-density pattern, as expected [4], but paradoxically, it reduces the apparent separation of dot pairs and induces apparent shrinkage of geometric form. This demonstrates for the first time a contrary linkage between perceived density and perceived extent. Separation and size appear to be expressed relative to a variable spatial metric whose properties, while not directly observable, are revealed by reductions in both apparent size and texture density. PMID:27426520

  9. Rotation parameters and shapes of 15 asteroids

    NASA Astrophysics Data System (ADS)

    Tungalag, N.; Shevchenko, V. G.; Lupishko, D. F.

    2002-12-01

    With the use of the combined method (the amplitude and magnitude method plus the epoch method) pole coordinates, sidereal rotation periods, and axial ratios of triaxial ellipsoid figures for asteroids 22 Kalliope, 75 Eurydike, 93 Minerva, 97 Klotho, 105 Artemis, 113 Amalthea, 119 Althaea, 201 Penelope, 270 Anahita, 338 Budrosa, 487 Venetia, 674 Rachele, 776 Berbericia, 887 Alinda, nd 951 Gaspra were determined. For eight of them (asteroids 75, 97, 105, 113, 119, 338, 674, and 887) these values were obtained for the first time. We used the numerical photometric asteroid model based on ellipsoidal asteroid shape, homogeneous albedo distribution over the surface, and Akimov's scattering law.

  10. Shape threat detection via adaptive computed tomography

    NASA Astrophysics Data System (ADS)

    Masoudi, Ahmad; Thamvichai, Ratchaneekorn; Neifeld, Mark A.

    2016-05-01

    X-ray Computed Tomography (CT) is used widely for screening purposes. Conventional x-ray threat detection systems employ image reconstruction and segmentation algorithms prior to making threat/no-threat decisions. We find that in many cases these pre-processing steps can degrade detection performance. Therefore in this work we will investigate methods that operate directly on the CT measurements. We analyze a fixed-gantry system containing 25 x-ray sources and 2200 photon counting detectors. We present a new method for improving threat detection performance. This new method is a so-called greedy adaptive algorithm which at each time step uses information from previous measurements to design the next measurement. We utilize sequential hypothesis testing (SHT) in order to derive both the optimal "next measurement" and the stopping criterion to insure a target probability of error Pe. We find that selecting the next x-ray source according to such a greedy adaptive algorithm, we can reduce Pe by a factor of 42.4× relative to the conventional measurement sequence employing all 25 sources in sequence.

  11. Shape and Individual Variability of the Blur Adaptation Curve

    PubMed Central

    Vera-Diaz, Fuensanta A.; Woods, Russell L.; Peli, Eli

    2010-01-01

    We are interested in clinical implications of adaptation to blurred and sharpened images. Therefore, we investigated repeatability, individual variability and characteristics of the adaptation curves in normally-sighted individuals (n=39). The point of subjective neutrality (PSN – the slope of the spatial spectrum of the image that appears normal) following adaptation was measured for each adaptation level and was used to derive individual adaptation curves for each subject. Adaptation curves were fitted with a modified Tukey biweight function as the curves were found to be tumbled-S shaped and asymmetrical for blur and sharp in some subjects. The adaptation curve was found to be an individual characteristic as inter-subject variability exceeds test-retest variability. The existence of individual variability may have implications for the prescription and clinical success of optical devices as well as image enhancement rehabilitation options. PMID:20417657

  12. How Neutrophils Shape Adaptive Immune Responses

    PubMed Central

    Leliefeld, Pieter H. C.; Koenderman, Leo; Pillay, Janesh

    2015-01-01

    Neutrophils are classically considered as cells pivotal for the first line of defense against invading pathogens. In recent years, evidence has accumulated that they are also important in the orchestration of adaptive immunity. Neutrophils rapidly migrate in high numbers to sites of inflammation (e.g., infection, tissue damage, and cancer) and are subsequently able to migrate to draining lymph nodes (LNs). Both at the site of inflammation as well as in the LNs, neutrophils can engage with lymphocytes and antigen-presenting cells. This crosstalk occurs either directly via cell–cell contact or via mediators, such as proteases, cytokines, and radical oxygen species. In this review, we will discuss the current knowledge regarding locations and mechanisms of interaction between neutrophils and lymphocytes in the context of homeostasis and various pathological conditions. In addition, we will highlight the complexity of the microenvironment that is involved in the generation of suppressive or stimulatory neutrophil phenotypes. PMID:26441976

  13. Shape Parameter for a Non-Axisymmetric Isothermal Dendrite

    NASA Technical Reports Server (NTRS)

    McFadden, G. B.; Coriell, S. R.; Sekerka, R. F.

    1999-01-01

    In previous work, we found approximate solutions for paraboloids having perturbations with four-fold axial symmetry in order to model dendritic growth in cubic materials. These solutions provide self-consistent corrections through second order in a shape parameter e to the Peclet number-supercooling relation of the Ivantsov solution. The parameter e is proportional to the amplitude of the four-fold correction to the dendrite shape, as measured from the Ivantsov paraboloid of revolution. We calculate e by comparing the dendrite tip shape to the portion of the equilibrium shape near the growth direction, (001), for anisotropic surface free energy, where the ni are components of the unit normal of the crystal surface. This comparison results in epsilon = -2(epsilon 4), independent of the Peclet number. From the experimental value of epsilon 4, we find epsilon approximately 0.011, in good agreement with the measured value epsilon approximately 0.008 of LaCombe et al.

  14. Electro-bending characterization of adaptive 3D fiber reinforced plastics based on shape memory alloys

    NASA Astrophysics Data System (ADS)

    Ashir, Moniruddoza; Hahn, Lars; Kluge, Axel; Nocke, Andreas; Cherif, Chokri

    2016-03-01

    The industrial importance of fiber reinforced plastics (FRPs) is growing steadily in recent years, which are mostly used in different niche products, has been growing steadily in recent years. The integration of sensors and actuators in FRP is potentially valuable for creating innovative applications and therefore the market acceptance of adaptive FRP is increasing. In particular, in the field of highly stressed FRP, structural integrated systems for continuous component parts monitoring play an important role. This presented work focuses on the electro-mechanical characterization of adaptive three-dimensional (3D)FRP with integrated textile-based actuators. Here, the friction spun hybrid yarn, consisting of shape memory alloy (SMA) in wire form as core, serves as an actuator. Because of the shape memory effect, the SMA-hybrid yarn returns to its original shape upon heating that also causes the deformation of adaptive 3D FRP. In order to investigate the influences of the deformation behavior of the adaptive 3D FRP, investigations in this research are varied according to the structural parameters such as radius of curvature of the adaptive 3D FRP, fabric types and number of layers of the fabric in the composite. Results show that reproducible deformations can be realized with adaptive 3D FRP and that structural parameters have a significant impact on the deformation capability.

  15. Additional Investigations of Ice Shape Sensitivity to Parameter Variations

    NASA Technical Reports Server (NTRS)

    Miller, Dean R.; Potapczuk, Mark G.; Langhals, Tammy J.

    2006-01-01

    A second parameter sensitivity study was conducted at the NASA Glenn Research Center's Icing Research Tunnel (IRT) using a 36 in. chord (0.91 m) NACA-0012 airfoil. The objective of this work was to further investigate the feasibility of using ice shape feature changes to define requirements for the simulation and measurement of SLD and appendix C icing conditions. A previous study concluded that it was feasible to use changes in ice shape features (e.g., ice horn angle, ice horn thickness, and ice shape mass) to detect relatively small variations in icing spray condition parameters (LWC, MVD, and temperature). The subject of this current investigation extends the scope of this previous work, by also examining the effect of icing tunnel spray-bar parameter variations (water pressure, air pressure) on ice shape feature changes. The approach was to vary spray-bar water pressure and air pressure, and then evaluate the effects of these parameter changes on the resulting ice shapes. This paper will provide a description of the experimental method, present selected experimental results, and conclude with an evaluation of these results.

  16. Interference and Shaping in Sensorimotor Adaptations with Rewards

    PubMed Central

    Darshan, Ran; Leblois, Arthur; Hansel, David

    2014-01-01

    When a perturbation is applied in a sensorimotor transformation task, subjects can adapt and maintain performance by either relying on sensory feedback, or, in the absence of such feedback, on information provided by rewards. For example, in a classical rotation task where movement endpoints must be rotated to reach a fixed target, human subjects can successfully adapt their reaching movements solely on the basis of binary rewards, although this proves much more difficult than with visual feedback. Here, we investigate such a reward-driven sensorimotor adaptation process in a minimal computational model of the task. The key assumption of the model is that synaptic plasticity is gated by the reward. We study how the learning dynamics depend on the target size, the movement variability, the rotation angle and the number of targets. We show that when the movement is perturbed for multiple targets, the adaptation process for the different targets can interfere destructively or constructively depending on the similarities between the sensory stimuli (the targets) and the overlap in their neuronal representations. Destructive interferences can result in a drastic slowdown of the adaptation. As a result of interference, the time to adapt varies non-linearly with the number of targets. Our analysis shows that these interferences are weaker if the reward varies smoothly with the subject's performance instead of being binary. We demonstrate how shaping the reward or shaping the task can accelerate the adaptation dramatically by reducing the destructive interferences. We argue that experimentally investigating the dynamics of reward-driven sensorimotor adaptation for more than one sensory stimulus can shed light on the underlying learning rules. PMID:24415925

  17. Adaptive shaping of cortical response selectivity in the vibrissa pathway

    PubMed Central

    Zheng, He J. V.; Wang, Qi

    2015-01-01

    One embodiment of context-dependent sensory processing is bottom-up adaptation, where persistent stimuli decrease neuronal firing rate over hundreds of milliseconds. Adaptation is not, however, simply the fatigue of the sensory pathway, but shapes the information flow and selectivity to stimulus features. Adaptation enhances spatial discriminability (distinguishing stimulus location) while degrading detectability (reporting presence of the stimulus), for both the ideal observer of the cortex and awake, behaving animals. However, how the dynamics of the adaptation shape the cortical response and this detection and discrimination tradeoff is unknown, as is to what degree this phenomenon occurs on a continuum as opposed to a switching of processing modes. Using voltage-sensitive dye imaging in anesthetized rats to capture the temporal and spatial characteristics of the cortical response to tactile inputs, we showed that the suppression of the cortical response, in both magnitude and spatial spread, is continuously modulated by the increasing amount of energy in the adapting stimulus, which is nonuniquely determined by its frequency and velocity. Single-trial ideal observer analysis demonstrated a tradeoff between detectability and spatial discriminability up to a moderate amount of adaptation, which corresponds to the frequency range in natural whisking. This was accompanied by a decrease in both detectability and discriminability with high-energy adaptation, which indicates a more complex coupling between detection and discrimination than a simple switching of modes. Taken together, the results suggest that adaptation operates on a continuum and modulates the tradeoff between detectability and discriminability that has implications for information processing in ethological contexts. PMID:25787959

  18. Adaptive optimisation of a generalised phase contrast beam shaping system

    NASA Astrophysics Data System (ADS)

    Kenny, F.; Choi, F. S.; Glückstad, J.; Booth, M. J.

    2015-05-01

    The generalised phase contrast (GPC) method provides versatile and efficient light shaping for a range of applications. We have implemented a generalised phase contrast system that used two passes on a single spatial light modulator (SLM). Both the pupil phase distribution and the phase contrast filter were generated by the SLM. This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter. A feedback method for the on-line optimisation of these properties was also developed. Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast.

  19. Robust design of configurations and parameters of adaptable products

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Chen, Yongliang; Xue, Deyi; Gu, Peihua

    2014-03-01

    An adaptable product can satisfy different customer requirements by changing its configuration and parameter values during the operation stage. Design of adaptable products aims at reducing the environment impact through replacement of multiple different products with single adaptable ones. Due to the complex architecture, multiple functional requirements, and changes of product configurations and parameter values in operation, impact of uncertainties to the functional performance measures needs to be considered in design of adaptable products. In this paper, a robust design approach is introduced to identify the optimal design configuration and parameters of an adaptable product whose functional performance measures are the least sensitive to uncertainties. An adaptable product in this paper is modeled by both configurations and parameters. At the configuration level, methods to model different product configuration candidates in design and different product configuration states in operation to satisfy design requirements are introduced. At the parameter level, four types of product/operating parameters and relations among these parameters are discussed. A two-level optimization approach is developed to identify the optimal design configuration and its parameter values of the adaptable product. A case study is implemented to illustrate the effectiveness of the newly developed robust adaptable design method.

  20. Radar and scattering parameters through falling hydrometeors with axisymmetric shapes.

    PubMed

    Battaglia, A; Prodi, F; Sturniolo, O

    2001-06-20

    Falling raindrops and other hydrometeors have, in general, nonspherical shapes and mean canting angles that are due to aerodynamic and gravitational forces. We use the T matrix and the quantum theory of angular momentum to compute extinction matrices, scattering and absorption cross sections, backscattering matrices, and, from these quantities, radar parameters. A monodisperse population of rain with axially symmetric distribution over orientations where the axis of symmetry is the local direction of air flow about the raindrops is considered. Oblate spheroids with axial ratios that depend on size and appropriate series of Chebyshev polynomials were assumed for definition of the shapes of raindrops. Computations were performed at common microwave frequencies for several temperatures, incidence angles, and degrees of particle wobble about a preferred orientation. Results reveal the importance of the role of orientation distribution and particle size and the shape of radar parameters in these computations for a region of moderate-sized raindrops. PMID:18357330

  1. Shape Adaptive, Robust Iris Feature Extraction from Noisy Iris Images

    PubMed Central

    Ghodrati, Hamed; Dehghani, Mohammad Javad; Danyali, Habibolah

    2013-01-01

    In the current iris recognition systems, noise removing step is only used to detect noisy parts of the iris region and features extracted from there will be excluded in matching step. Whereas depending on the filter structure used in feature extraction, the noisy parts may influence relevant features. To the best of our knowledge, the effect of noise factors on feature extraction has not been considered in the previous works. This paper investigates the effect of shape adaptive wavelet transform and shape adaptive Gabor-wavelet for feature extraction on the iris recognition performance. In addition, an effective noise-removing approach is proposed in this paper. The contribution is to detect eyelashes and reflections by calculating appropriate thresholds by a procedure called statistical decision making. The eyelids are segmented by parabolic Hough transform in normalized iris image to decrease computational burden through omitting rotation term. The iris is localized by an accurate and fast algorithm based on coarse-to-fine strategy. The principle of mask code generation is to assign the noisy bits in an iris code in order to exclude them in matching step is presented in details. An experimental result shows that by using the shape adaptive Gabor-wavelet technique there is an improvement on the accuracy of recognition rate. PMID:24696801

  2. Shape adaptive, robust iris feature extraction from noisy iris images.

    PubMed

    Ghodrati, Hamed; Dehghani, Mohammad Javad; Danyali, Habibolah

    2013-10-01

    In the current iris recognition systems, noise removing step is only used to detect noisy parts of the iris region and features extracted from there will be excluded in matching step. Whereas depending on the filter structure used in feature extraction, the noisy parts may influence relevant features. To the best of our knowledge, the effect of noise factors on feature extraction has not been considered in the previous works. This paper investigates the effect of shape adaptive wavelet transform and shape adaptive Gabor-wavelet for feature extraction on the iris recognition performance. In addition, an effective noise-removing approach is proposed in this paper. The contribution is to detect eyelashes and reflections by calculating appropriate thresholds by a procedure called statistical decision making. The eyelids are segmented by parabolic Hough transform in normalized iris image to decrease computational burden through omitting rotation term. The iris is localized by an accurate and fast algorithm based on coarse-to-fine strategy. The principle of mask code generation is to assign the noisy bits in an iris code in order to exclude them in matching step is presented in details. An experimental result shows that by using the shape adaptive Gabor-wavelet technique there is an improvement on the accuracy of recognition rate. PMID:24696801

  3. An adaptive control system for wing TE shape control

    NASA Astrophysics Data System (ADS)

    Dimino, I.; Concilio, A.; Schueller, M.; Gratias, A.

    2013-03-01

    A key technology to enable morphing aircraft for enhanced aerodynamic performance is the design of an adaptive control system able to emulate target structural shapes. This paper presents an approach to control the shape of a morphing wing by employing internal, integrated actuators acting on the trailing edge. The adaptive-wing concept employs active ribs, driven by servo actuators, controlled in turn by a dedicated algorithm aimed at shaping the wing cross section, according to a pre-defined geometry. The morphing control platform is presented and a suitable control algorithm is implemented in a dedicated routine for real-time simulations. The work is organized as follows. A finite element model of the uncontrolled, non-actuated structure is used to obtain the plant model for actuator torque and displacement control. After having characterized and simulated pure rotary actuator behavior over the structure, selected target wing shapes corresponding to rigid trailing edge rotations are achieved through both open-loop and closed-loop control logics.

  4. Phylogeny and adaptation shape the teeth of insular mice.

    PubMed

    Ledevin, Ronan; Chevret, Pascale; Ganem, Guila; Britton-Davidian, Janice; Hardouin, Emilie A; Chapuis, Jean-Louis; Pisanu, Benoit; da Luz Mathias, Maria; Schlager, Stefan; Auffray, Jean-Christophe; Renaud, Sabrina

    2016-02-10

    By accompanying human travels since prehistorical times, the house mouse dispersed widely throughout the world, and colonized many islands. The origin of the travellers determined the phylogenetic source of the insular mice, which encountered diverse ecological and environmental conditions on the various islands. Insular mice are thus an exceptional model to disentangle the relative role of phylogeny, ecology and climate in evolution. Molar shape is known to vary according to phylogeny and to respond to adaptation. Using for the first time a three-dimensional geometric morphometric approach, compared with a classical two-dimensional quantification, the relative effects of size variation, phylogeny, climate and ecology were investigated on molar shape diversity across a variety of islands. Phylogeny emerged as the factor of prime importance in shaping the molar. Changes in competition level, mostly driven by the presence or absence of the wood mouse on the different islands, appeared as the second most important effect. Climate and size differences accounted for slight shape variation. This evidences a balanced role of random differentiation related to history of colonization, and of adaptation possibly related to resource exploitation. PMID:26842576

  5. Preliminary Investigation of Ice Shape Sensitivity to Parameter Variations

    NASA Technical Reports Server (NTRS)

    Miller, Dean R.; Potapczuk, Mark G.; Langhals, Tammy J.

    2005-01-01

    A parameter sensitivity study was conducted at the NASA Glenn Research Center's Icing Research Tunnel (IRT) using a 36 in. chord (0.91 m) NACA-0012 airfoil. The objective of this preliminary work was to investigate the feasibility of using ice shape feature changes to define requirements for the simulation and measurement of SLD icing conditions. It was desired to identify the minimum change (threshold) in a parameter value, which yielded an observable change in the ice shape. Liquid Water Content (LWC), drop size distribution (MVD), and tunnel static temperature were varied about a nominal value, and the effects of these parameter changes on the resulting ice shapes were documented. The resulting differences in ice shapes were compared on the basis of qualitative and quantitative criteria (e.g., mass, ice horn thickness, ice horn angle, icing limits, and iced area). This paper will provide a description of the experimental method, present selected experimental results, and conclude with an evaluation of these results, followed by a discussion of recommendations for future research.

  6. Design of a shape adaptive airfoil actuated by a Shape Memory Alloy strip for airplane tail

    NASA Astrophysics Data System (ADS)

    Shirzadeh, R.; Raissi Charmacani, K.; Tabesh, M.

    2011-04-01

    Of the factors that mainly affect the efficiency of the wing during a special flow regime, the shape of its airfoil cross section is the most significant. Airfoils are generally designed for a specific flight condition and, therefore, are not fully optimized in all flight conditions. It is very desirable to have an airfoil with the ability to change its shape based on the current regime. Shape memory alloy (SMA) actuators activate in response to changes in the temperature and can recover their original configuration after being deformed. This study presents the development of a method to control the shape of an airfoil using SMA actuators. To predict the thermomechanical behaviors of an SMA thin strip, 3D incremental formulation of the SMA constitutive model is implemented in FEA software package ABAQUS. The interactions between the airfoil structure and SMA thin strip actuator are investigated. Also, the aerodynamic performance of a standard airfoil with a plain flap is compared with an adaptive airfoil.

  7. On choosing ?optimal? shape parameters for RBF approximation

    NASA Astrophysics Data System (ADS)

    Fasshauer, Gregory; Zhang, Jack

    2007-08-01

    Many radial basis function (RBF) methods contain a free shape parameter that plays an important role for the accuracy of the method. In most papers the authors end up choosing this shape parameter by trial and error or some other ad hoc means. The method of cross validation has long been used in the statistics literature, and the special case of leave-one-out cross validation forms the basis of the algorithm for choosing an optimal value of the shape parameter proposed by Rippa in the setting of scattered data interpolation with RBFs. We discuss extensions of this approach that can be applied in the setting of iterated approximate moving least squares approximation of function value data and for RBF pseudo-spectral methods for the solution of partial differential equations. The former method can be viewed as an efficient alternative to ridge regression or smoothing spline approximation, while the latter forms an extension of the classical polynomial pseudo-spectral approach. Numerical experiments illustrating the use of our algorithms are included.

  8. Shape memory alloy actuated adaptive exhaust nozzle for jet engine

    NASA Technical Reports Server (NTRS)

    Song, Gangbing (Inventor); Ma, Ning (Inventor)

    2009-01-01

    The proposed adaptive exhaust nozzle features an innovative use of the shape memory alloy (SMA) actuators for actively control of the opening area of the exhaust nozzle for jet engines. The SMA actuators remotely control the opening area of the exhaust nozzle through a set of mechanism. An important advantage of using SMA actuators is the reduction of weight of the actuator system for variable area exhaust nozzle. Another advantage is that the SMA actuator can be activated using the heat from the exhaust and eliminate the need of other energy source. A prototype has been designed and fabricated. The functionality of the proposed SMA actuated adaptive exhaust nozzle is verified in the open-loop tests.

  9. Coral thermal tolerance shaped by local adaptation of photosymbionts

    NASA Astrophysics Data System (ADS)

    Howells, E. J.; Beltran, V. H.; Larsen, N. W.; Bay, L. K.; Willis, B. L.; van Oppen, M. J. H.

    2012-02-01

    Coral thermal tolerance is strongly influenced by the identity of obligate photosymbionts, which encompass numerous types belonging to the dinoflagellate genus Symbiodinium. Physiological advantages achieved by partnering with functionally diverse symbionts have been assumed to be available only to corals that can form associations with multiple Symbiodinium types. Functional variation among populations of the same type of Symbiodinium has been overlooked, despite local adaptation being feasible because of large population sizes, genetic isolation and short asexual generation times. Here we demonstrate divergent thermal tolerance in a generalist Symbiodinium type from two different thermal environments. Symbiodinium from the warmer reef maintained greater photo-chemical performance and survivorship when exposed to an elevated temperature of 32°C, both in symbiosis and in culture. Juvenile corals associated with Symbiodinium from the warmer reef grew rapidly when exposed to 32°C, yet underwent bleaching and tissue death when associated with Symbiodinium from the cooler reef. These results demonstrate that Symbiodinium types can adapt to local differences in thermal climate and that this adaptation shapes the fitness of coral hosts. If Symbiodinium populations are able to further adapt to increases in temperature at the pace at which ocean climates warm, they may assist corals to increase their thermal tolerance and persist into the future.

  10. Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues.

    PubMed

    Gómez-González, Susana; Ojeda, Fernando; Torres-Morales, Patricio; Palma, Jazmín E

    2016-01-01

    Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene. PMID:27438267

  11. Seed Pubescence and Shape Modulate Adaptive Responses to Fire Cues

    PubMed Central

    Gómez-González, Susana; Ojeda, Fernando; Torres-Morales, Patricio; Palma, Jazmín E.

    2016-01-01

    Post-fire recruitment by seeds is regarded as an adaptive response in fire-prone ecosystems. Nevertheless, little is known about which heritable seed traits are functional to the main signals of fire (heat and smoke), thus having the potential to evolve. Here, we explored whether three seed traits (pubescence, dormancy and shape) and fire regime modulate seed response to fire cues(heat and smoke). As a model study system, we used Helenium aromaticum (Asteraceae), a native annual forb from the Chilean matorral, where fires are anthropogenic. We related seed trait values with fitness responses (germination and survival) after exposure to heat-shock and smoke experimental treatments on seeds from 10 H. aromaticum wild populations. We performed a phenotypic selection experiment to examine the relationship of seed traits with post-treatment fitness within a population (adaptive hypothesis). We then explored whether fire frequency in natural habitats was associated with trait expression across populations, and with germination and survival responses to experimental fire-cues. We found that populations subjected to higher fire frequency had, in average, more rounded and pubescent seeds than populations from rarely burned areas. Populations with more rounded and pubescent seeds were more resistant to 80°C heat-shock and smoke treatments.There was correlated selection on seed traits: pubescent-rounded or glabrouscent-elongated seeds had the highest probability of germinating after heat-shock treatments. Seed pubescence and shape in H. aromaticum are heritable traits that modulate adaptive responses to fire. Our results provide new insights into the process of plant adaptation to fire and highlight the relevance of human-made fires as a strong evolutionary agent in the Anthropocene. PMID:27438267

  12. Adaptive optimisation of a generalised phase contrast beam shaping system

    PubMed Central

    Kenny, F.; Choi, F.S.; Glückstad, J.; Booth, M.J.

    2015-01-01

    The generalised phase contrast (GPC) method provides versatile and efficient light shaping for a range of applications. We have implemented a generalised phase contrast system that used two passes on a single spatial light modulator (SLM). Both the pupil phase distribution and the phase contrast filter were generated by the SLM. This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter. A feedback method for the on-line optimisation of these properties was also developed. Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast. PMID:26089573

  13. Source parameter estimation in inhomogeneous volume conductors of arbitrary shape.

    PubMed

    Oostendorp, T F; van Oosterom, A

    1989-03-01

    In this paper it is demonstrated that the use of a direct matrix inverse in the solution of the forward problem in volume conduction problems greatly facilitates the application of standard, nonlinear parameter estimation procedures for finding the strength as well as the location of current sources inside an inhomogeneous volume conductor of arbitrary shape from potential measurements at the outer surface (inverse procedure). This, in turn, facilitates the inclusion of a priori constraints. Where possible, the performance of the method is compared to that of the Gabor-Nelson method. Applications are in the fields of bioelectricity (e.g., electrocardiography and electroencephalography). PMID:2921073

  14. Adaptive Shape Functions and Internal Mesh Adaptation for Modelling Progressive Failure in Adhesively Bonded Joints

    NASA Technical Reports Server (NTRS)

    Stapleton, Scott; Gries, Thomas; Waas, Anthony M.; Pineda, Evan J.

    2014-01-01

    Enhanced finite elements are elements with an embedded analytical solution that can capture detailed local fields, enabling more efficient, mesh independent finite element analysis. The shape functions are determined based on the analytical model rather than prescribed. This method was applied to adhesively bonded joints to model joint behavior with one element through the thickness. This study demonstrates two methods of maintaining the fidelity of such elements during adhesive non-linearity and cracking without increasing the mesh needed for an accurate solution. The first method uses adaptive shape functions, where the shape functions are recalculated at each load step based on the softening of the adhesive. The second method is internal mesh adaption, where cracking of the adhesive within an element is captured by further discretizing the element internally to represent the partially cracked geometry. By keeping mesh adaptations within an element, a finer mesh can be used during the analysis without affecting the global finite element model mesh. Examples are shown which highlight when each method is most effective in reducing the number of elements needed to capture adhesive nonlinearity and cracking. These methods are validated against analogous finite element models utilizing cohesive zone elements.

  15. Adaptive shape coding for perceptual decisions in the human brain

    PubMed Central

    Kourtzi, Zoe; Welchman, Andrew E.

    2015-01-01

    In its search for neural codes, the field of visual neuroscience has uncovered neural representations that reflect the structure of stimuli of variable complexity from simple features to object categories. However, accumulating evidence suggests an adaptive neural code that is dynamically shaped by experience to support flexible and efficient perceptual decisions. Here, we review work showing that experience plays a critical role in molding midlevel visual representations for perceptual decisions. Combining behavioral and brain imaging measurements, we demonstrate that learning optimizes feature binding for object recognition in cluttered scenes, and tunes the neural representations of informative image parts to support efficient categorical judgements. Our findings indicate that similar learning mechanisms may mediate long-term optimization through development, tune the visual system to fundamental principles of feature binding, and optimize feature templates for perceptual decisions. PMID:26024511

  16. Binary hologram generation based on shape adaptive sampling

    NASA Astrophysics Data System (ADS)

    Tsang, P. W. M.; Pan, Y.; Poon, T.-C.

    2014-05-01

    Past research has revealed that by down-sampling the projected intensity profile of a source object scene with a regular sampling lattice, a binary Fresnel hologram can be generated swiftly to preserve favorable quality on its reconstructed image. However, this method also results in a prominent textural pattern which is conflicting to the geometrical profile of the object scene, leading to an unnatural visual perception. In this paper, we shall overcome this problem with a down-sampling process that is adaptive to the geometry of the object. Experimental results demonstrate that by applying our proposed method to generate a binary hologram, the reconstructed image is rendered with a texture which abides with the shape of the three-dimensional object(s).

  17. Beam shaping for laser-based adaptive optics in astronomy.

    PubMed

    Béchet, Clémentine; Guesalaga, Andrés; Neichel, Benoit; Fesquet, Vincent; González-Núñez, Héctor; Zúñiga, Sebastián; Escarate, Pedro; Guzman, Dani

    2014-06-01

    The availability and performance of laser-based adaptive optics (AO) systems are strongly dependent on the power and quality of the laser beam before being projected to the sky. Frequent and time-consuming alignment procedures are usually required in the laser systems with free-space optics to optimize the beam. Despite these procedures, significant distortions of the laser beam have been observed during the first two years of operation of the Gemini South multi-conjugate adaptive optics system (GeMS). A beam shaping concept with two deformable mirrors is investigated in order to provide automated optimization of the laser quality for astronomical AO. This study aims at demonstrating the correction of quasi-static aberrations of the laser, in both amplitude and phase, testing a prototype of this two-deformable mirror concept on GeMS. The paper presents the results of the preparatory study before the experimental phase. An algorithm to control amplitude and phase correction, based on phase retrieval techniques, is presented with a novel unwrapping method. Its performance is assessed via numerical simulations, using aberrations measured at GeMS as reference. The results predict effective amplitude and phase correction of the laser distortions with about 120 actuators per mirror and a separation of 1.4 m between the mirrors. The spot size is estimated to be reduced by up to 15% thanks to the correction. In terms of AO noise level, this has the same benefit as increasing the photon flux by 40%. PMID:24921496

  18. Characteristic tensile strength and Weibull shape parameter of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Klein, Claude A.

    2007-06-01

    Recently, it has been argued [N. M. Pugno and R. S. Ruoff, J. Appl. Phys. 99, 024301 (2006)] that available carbon-nanotube (CNT) tensile strength data do not obey the "classical" Weibull statistical model. In this paper we formulate Weibull's theory in a manner suitable for assessing CNT fracture-strength data and demonstrate that, on taking into account the area S subjected to uniform tensile stresses, the data are consistent with Weibull's model. Based on available data, a characteristic strength σC (S=1μm2) equal to 17.6±2.5GPa in conjunction with a shape parameter m equal to 2.77±0.34 provides a good description of the CNT fracture strength. In terms of effective strengths, and on assuming that the relevant area-scaling laws apply, carbon nanotubes and diamond nanofilms exhibit similar features for stressed areas ranging from 1to104μm2.

  19. On Using Exponential Parameter Estimators with an Adaptive Controller

    NASA Technical Reports Server (NTRS)

    Patre, Parag; Joshi, Suresh M.

    2011-01-01

    Typical adaptive controllers are restricted to using a specific update law to generate parameter estimates. This paper investigates the possibility of using any exponential parameter estimator with an adaptive controller such that the system tracks a desired trajectory. The goal is to provide flexibility in choosing any update law suitable for a given application. The development relies on a previously developed concept of controller/update law modularity in the adaptive control literature, and the use of a converse Lyapunov-like theorem. Stability analysis is presented to derive gain conditions under which this is possible, and inferences are made about the tracking error performance. The development is based on a class of Euler-Lagrange systems that are used to model various engineering systems including space robots and manipulators.

  20. Covariations between Shell-Growth Parameters and the Control of the Ranges of Variation of Functionally Relevant Shell-Shape Parameters in Bivalves: A Theoretical Approach

    PubMed Central

    Béguinot, Jean

    2014-01-01

    Major traits of shell shape in bivalves may alternatively be described in terms of (i) functionally relevant parameters, assumed to play a significant role in the adaptation of bivalves molluscs to their environments (such as the shell-outline elongation E, ventral convexity K, and dissymmetry D), or (ii) growth-based parameters, directly controlled by the animal. Due to the geometrical linkage between functionally-relevant and growth-based parameters, adaptive constraints that may either widen or narrow the respective ranges of variations of the functional parameters lead to the onset of specific covariations (either positive or negative) between the growth-based parameters. This has practical interest since adaptive constraints are often difficult to identify directly, while they can be conveniently inferred indirectly via the easily recorded patterns of covariances between growth-based parameters. Hereafter, I provide the theoretical background of this tool, including (1) establishing the geometrical relationships between growth-based and functionally relevant parameters and (2) then specifying the correspondences between the different patterns of adaptive constraints, widening or narrowing the variations of the functional parameters and the corresponding patterns of covariations between the growth-based parameters. Illustrative examples of the practical use of this tool are provided, considering both interspecific and intraspecific variations within marine and fresh-water clams.

  1. Proteasome function shapes innate and adaptive immune responses.

    PubMed

    Kammerl, Ilona E; Meiners, Silke

    2016-08-01

    The proteasome system degrades more than 80% of intracellular proteins into small peptides. Accordingly, the proteasome is involved in many essential cellular functions, such as protein quality control, transcription, immune responses, cell signaling, and apoptosis. Moreover, degradation products are loaded onto major histocompatibility class I molecules to communicate the intracellular protein composition to the immune system. The standard 20S proteasome core complex contains three distinct catalytic active sites that are exchanged upon stimulation with inflammatory cytokines to form the so-called immunoproteasome. Immunoproteasomes are constitutively expressed in immune cells and have different proteolytic activities compared with standard proteasomes. They are rapidly induced in parenchymal cells upon intracellular pathogen infection and are crucial for priming effective CD8(+) T-cell-mediated immune responses against infected cells. Beyond shaping these adaptive immune reactions, immunoproteasomes also regulate the function of immune cells by degradation of inflammatory and immune mediators. Accordingly, they emerge as novel regulators of innate immune responses. The recently unraveled impairment of immunoproteasome function by environmental challenges and by genetic variations of immunoproteasome genes might represent a currently underestimated risk factor for the development and progression of lung diseases. In particular, immunoproteasome dysfunction will dampen resolution of infections, thereby promoting exacerbations, may foster autoimmunity in chronic lung diseases, and possibly contributes to immune evasion of tumor cells. Novel pharmacological tools, such as site-specific inhibitors of the immunoproteasome, as well as activity-based probes, however, hold promises as innovative therapeutic drugs for respiratory diseases and biomarker profiling, respectively. PMID:27343191

  2. Parameter adaptation technique for rapid synchronization and secure communication

    NASA Astrophysics Data System (ADS)

    Mittal, A. K.; Dwivedi, A.; Dwivedi, S.

    2014-06-01

    An effort is made here to show how parameter adaptation can be used for achieving rapid synchronization between two chaotic systems in a time much smaller than the time scale of chaotic oscillations. This rapid synchronization can be used for faster and more secure communication of digital messages. Different symbols of the message are coded by assigning different values to a parameter set. At the receiving end the parameter values quickly adapt to the changing transmitter parameters, thereby permitting the messages to be decoded. The technique presented here is significantly more secure compared to other similar schemes because in our scheme the transmitting parameters change so rapidly that an intruder cannot infer any information about the attractors corresponding to the different parameter values. Another feature, which enhances security, is that a subsystem of the transmitter can be changed, without having to convey this information to the bona fide recipient. Thus for the same plaintext and the same key, several different cipher-texts can be generated. Further, the variables, whose evolution equations contain the coding parameters, are not transmitted.

  3. Adaptive Shape Kernel-Based Mean Shift Tracker in Robot Vision System

    PubMed Central

    2016-01-01

    This paper proposes an adaptive shape kernel-based mean shift tracker using a single static camera for the robot vision system. The question that we address in this paper is how to construct such a kernel shape that is adaptive to the object shape. We perform nonlinear manifold learning technique to obtain the low-dimensional shape space which is trained by training data with the same view as the tracking video. The proposed kernel searches the shape in the low-dimensional shape space obtained by nonlinear manifold learning technique and constructs the adaptive kernel shape in the high-dimensional shape space. It can improve mean shift tracker performance to track object position and object contour and avoid the background clutter. In the experimental part, we take the walking human as example to validate that our method is accurate and robust to track human position and describe human contour. PMID:27379165

  4. Temporal pulse shaping: a key parameter for the laser welding of dental alloys.

    PubMed

    Bertrand, Caroline; Poulon-Quintin, Angeline

    2015-07-01

    This study aims to describe the effect of pulse shaping on the prevention of internal defects during laser welding for two dental alloys mainly used in prosthetic dentistry. Single spot, weld beads, and welds with 80 % overlapping were performed on Co-Cr-Mo and Pd-Ag-Sn cast plates with a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A specific welding procedure using adapted parameters to each alloy was completed. All the possibilities for pulse shaping were tested: (1) the square pulse shape as a default setting, (2) a rising edge slope for gradual heating, (3) a falling edge slope to slow the cooling process, and (4) a combination of rising and falling edges. The optimization of the pulse shape is supposed to produce defect-free welds (crack, pores, voids). Cross-section SEM observations and Vickers microhardness measurements were made. Pd-Ag-Sn was highly sensitive to hot cracking, and Co-Cr-Mo was more sensitive to voids and small porosities (sometimes combined with cracks). Using a slow cooling ramp allowed a better control on the solidification process for those two alloys always preventing internal defects. A rapid slope should be preferred for Co-Cr-Mo alloys due to its low-laser beam reflectivity. On the opposite, for Pd-Ag-Sn alloy, a slow rising slope should be preferred because this alloy has a high-laser beam reflectivity. PMID:24913424

  5. Adaptive Firefly Algorithm: Parameter Analysis and its Application

    PubMed Central

    Shen, Hong-Bin

    2014-01-01

    As a nature-inspired search algorithm, firefly algorithm (FA) has several control parameters, which may have great effects on its performance. In this study, we investigate the parameter selection and adaptation strategies in a modified firefly algorithm — adaptive firefly algorithm (AdaFa). There are three strategies in AdaFa including (1) a distance-based light absorption coefficient; (2) a gray coefficient enhancing fireflies to share difference information from attractive ones efficiently; and (3) five different dynamic strategies for the randomization parameter. Promising selections of parameters in the strategies are analyzed to guarantee the efficient performance of AdaFa. AdaFa is validated over widely used benchmark functions, and the numerical experiments and statistical tests yield useful conclusions on the strategies and the parameter selections affecting the performance of AdaFa. When applied to the real-world problem — protein tertiary structure prediction, the results demonstrated improved variants can rebuild the tertiary structure with the average root mean square deviation less than 0.4Å and 1.5Å from the native constrains with noise free and 10% Gaussian white noise. PMID:25397812

  6. Adaptive firefly algorithm: parameter analysis and its application.

    PubMed

    Cheung, Ngaam J; Ding, Xue-Ming; Shen, Hong-Bin

    2014-01-01

    As a nature-inspired search algorithm, firefly algorithm (FA) has several control parameters, which may have great effects on its performance. In this study, we investigate the parameter selection and adaptation strategies in a modified firefly algorithm - adaptive firefly algorithm (AdaFa). There are three strategies in AdaFa including (1) a distance-based light absorption coefficient; (2) a gray coefficient enhancing fireflies to share difference information from attractive ones efficiently; and (3) five different dynamic strategies for the randomization parameter. Promising selections of parameters in the strategies are analyzed to guarantee the efficient performance of AdaFa. AdaFa is validated over widely used benchmark functions, and the numerical experiments and statistical tests yield useful conclusions on the strategies and the parameter selections affecting the performance of AdaFa. When applied to the real-world problem - protein tertiary structure prediction, the results demonstrated improved variants can rebuild the tertiary structure with the average root mean square deviation less than 0.4Å and 1.5Å from the native constrains with noise free and 10% Gaussian white noise. PMID:25397812

  7. Controller Parameter Tuning for Systems with Hysteresis and Its Application to Shape Memory Alloy Actuators

    NASA Astrophysics Data System (ADS)

    Wakasa, Yuji; Kanagawa, Shinji; Tanaka, Kanya; Nishimura, Yuki

    This paper proposes a simple controller parameter tuning method that can compensate for hysteresis. The proposed method is based on the so-called fictitious reference iterative tuning (FRIT) technique which can easily tune controller parameters such as proportional-integral-derivative gains using a one-shot closed-loop experimental data. In the proposed framework, a simple hysteresis model is introduced to a control system, and its inverse is used as a hysteresis compensator. Since the hysteresis model is characterized with only three parameters, the related computational burden is moderate in the parameter tuning process. Also, the proposed FRIT method needs an only one-shot experiment as in the standard FRIT one, which implies that the feature of FRIT is well-maintained. In the optimization process, the so-called covariance matrix adaptation evolution strategy is used for simultaneously searching hysteresis parameters as well as controller parameters. The proposed FRIT method is applied to an experimental control system that comprises a shape memory alloy actuator, and its effectiveness is verified.

  8. Predicting accurate line shape parameters for CO2 transitions

    NASA Astrophysics Data System (ADS)

    Gamache, Robert R.; Lamouroux, Julien

    2013-11-01

    The vibrational dependence of CO2 half-widths and line shifts are given by a modification of the model proposed by Gamache and Hartmann [Gamache R, Hartmann J-M. J Quant Spectrosc Radiat Transfer 2004;83:119]. This model allows the half-widths and line shifts for a ro-vibrational transition to be expressed in terms of the number of vibrational quanta exchanged in the transition raised to a power and a reference ro-vibrational transition. Calculations were made for 24 bands for lower rotational quantum numbers from 0 to 160 for N2-, O2-, air-, and self-collisions with CO2. These data were extrapolated to J″=200 to accommodate several databases. Comparison of the CRB calculations with measurement gives very high confidence in the data. In the model a Quantum Coordinate is defined by (c1 |Δν1|+c2 |Δν2|+c3|Δν3|)p. The power p is adjusted and a linear least-squares fit to the data by the model expression is made. The procedure is iterated on the correlation coefficient, R, until [|R|-1] is less than a threshold. The results demonstrate the appropriateness of the model. The model allows the determination of the slope and intercept as a function of rotational transition, broadening gas, and temperature. From the data of the fits, the half-width, line shift, and the temperature dependence of the half-width can be estimated for any ro-vibrational transition, allowing spectroscopic CO2 databases to have complete information for the line shape parameters.

  9. Insights into the sequence parameters for halophilic adaptation.

    PubMed

    Nath, Abhigyan

    2016-03-01

    The sequence parameters for halophilic adaptation are still not fully understood. To understand the molecular basis of protein hypersaline adaptation, a detailed analysis is carried out, and investigated the likely association of protein sequence attributes to halophilic adaptation. A two-stage strategy is implemented, where in the first stage a supervised machine learning classifier is build, giving an overall accuracy of 86 % on stratified tenfold cross validation and 90 % on blind testing set, which are better than the previously reported results. The second stage consists of statistical analysis of sequence features and possible extraction of halophilic molecular signatures. The results of this study showed that, halophilic proteins are characterized by lower average charge, lower K content, and lower S content. A statistically significant preference/avoidance list of sequence parameters is also reported giving insights into the molecular basis of halophilic adaptation. D, Q, E, H, P, T, V are significantly preferred while N, C, I, K, M, F, S are significantly avoided. Among amino acid physicochemical groups, small, polar, charged, acidic and hydrophilic groups are preferred over other groups. The halophilic proteins also showed a preference for higher average flexibility, higher average polarity and avoidance for higher average positive charge, average bulkiness and average hydrophobicity. Some interesting trends observed in dipeptide counts are also reported. Further a systematic statistical comparison is undertaken for gaining insights into the sequence feature distribution in different residue structural states. The current analysis may facilitate the understanding of the mechanism of halophilic adaptation clearer, which can be further used for rational design of halophilic proteins. PMID:26520112

  10. How adaptation shapes spike rate oscillations in recurrent neuronal networks

    PubMed Central

    Augustin, Moritz; Ladenbauer, Josef; Obermayer, Klaus

    2012-01-01

    Neural mass signals from in-vivo recordings often show oscillations with frequencies ranging from <1 to 100 Hz. Fast rhythmic activity in the beta and gamma range can be generated by network-based mechanisms such as recurrent synaptic excitation-inhibition loops. Slower oscillations might instead depend on neuronal adaptation currents whose timescales range from tens of milliseconds to seconds. Here we investigate how the dynamics of such adaptation currents contribute to spike rate oscillations and resonance properties in recurrent networks of excitatory and inhibitory neurons. Based on a network of sparsely coupled spiking model neurons with two types of adaptation current and conductance-based synapses with heterogeneous strengths and delays we use a mean-field approach to analyze oscillatory network activity. For constant external input, we find that spike-triggered adaptation currents provide a mechanism to generate slow oscillations over a wide range of adaptation timescales as long as recurrent synaptic excitation is sufficiently strong. Faster rhythms occur when recurrent inhibition is slower than excitation and oscillation frequency increases with the strength of inhibition. Adaptation facilitates such network-based oscillations for fast synaptic inhibition and leads to decreased frequencies. For oscillatory external input, adaptation currents amplify a narrow band of frequencies and cause phase advances for low frequencies in addition to phase delays at higher frequencies. Our results therefore identify the different key roles of neuronal adaptation dynamics for rhythmogenesis and selective signal propagation in recurrent networks. PMID:23450654

  11. Study of adaptive correlation filter synthesis guided by the peak and shape of the correlation output

    NASA Astrophysics Data System (ADS)

    Campos Trujillo, Oliver G.; Díaz Blancas, Gerardo

    2014-09-01

    In recent years, many proposals that consider an adaptive perspective had been developed to solve some drawbacks, such as geometric distortions, background noise and target discrimination. The metrics are based only in the correlation peak output for the filter synthesis. In this paper, the correlation shape is studied to implement adaptive correlation filters guided by the peak and shape of the correlation output. Furthermore, the shape of correlation output is studied to improve the search in the filters bank. In addition, parallel algorithms are developed for accelerated the search in the filters bank. Some results are shown, such as time of synthesis, filter performance and comparisons with other adaptive correlation filter proposals.

  12. Adaptive MFR parameter control: fixed vs. variable probabilities of detection

    NASA Astrophysics Data System (ADS)

    Boers, Yvo; Driessen, Hans; Zwaga, Jitse

    2005-09-01

    In this paper an efficient adaptive parameter control scheme for Multi Function Radar (MFR) is used. This scheme has been introduced in.5 The scheme has been designed in such a way that it meets constraints on specific quantities that are relevant for target tracking while minimizing the energy spent. It is shown here, that this optimal scheme leads to a considerable variation of the realized detection probability, even within a single scenario. We also show that constraining or fixing the probability of detection to a certain predefined value leads to a considerable increase in the energy spent on the target. This holds even when one optimizes the fixed probability of detection. The bottom line message is that the detection probability is not a design parameter by itself, but merely the product of an optimal schedule.

  13. An adaptive regularization parameter choice strategy for multispectral bioluminescence tomography

    SciTech Connect

    Feng Jinchao; Qin Chenghu; Jia Kebin; Han Dong; Liu Kai; Zhu Shouping; Yang Xin; Tian Jie

    2011-11-15

    Purpose: Bioluminescence tomography (BLT) provides an effective tool for monitoring physiological and pathological activities in vivo. However, the measured data in bioluminescence imaging are corrupted by noise. Therefore, regularization methods are commonly used to find a regularized solution. Nevertheless, for the quality of the reconstructed bioluminescent source obtained by regularization methods, the choice of the regularization parameters is crucial. To date, the selection of regularization parameters remains challenging. With regards to the above problems, the authors proposed a BLT reconstruction algorithm with an adaptive parameter choice rule. Methods: The proposed reconstruction algorithm uses a diffusion equation for modeling the bioluminescent photon transport. The diffusion equation is solved with a finite element method. Computed tomography (CT) images provide anatomical information regarding the geometry of the small animal and its internal organs. To reduce the ill-posedness of BLT, spectral information and the optimal permissible source region are employed. Then, the relationship between the unknown source distribution and multiview and multispectral boundary measurements is established based on the finite element method and the optimal permissible source region. Since the measured data are noisy, the BLT reconstruction is formulated as l{sub 2} data fidelity and a general regularization term. When choosing the regularization parameters for BLT, an efficient model function approach is proposed, which does not require knowledge of the noise level. This approach only requests the computation of the residual and regularized solution norm. With this knowledge, we construct the model function to approximate the objective function, and the regularization parameter is updated iteratively. Results: First, the micro-CT based mouse phantom was used for simulation verification. Simulation experiments were used to illustrate why multispectral data were used

  14. The reduced order model problem in distributed parameter systems adaptive identification and control. [adaptive control of flexible spacecraft

    NASA Technical Reports Server (NTRS)

    Johnson, C. R., Jr.; Lawrence, D. A.

    1981-01-01

    The reduced order model problem in distributed parameter systems adaptive identification and control is investigated. A comprehensive examination of real-time centralized adaptive control options for flexible spacecraft is provided.

  15. Intelligent Modeling Combining Adaptive Neuro Fuzzy Inference System and Genetic Algorithm for Optimizing Welding Process Parameters

    NASA Astrophysics Data System (ADS)

    Gowtham, K. N.; Vasudevan, M.; Maduraimuthu, V.; Jayakumar, T.

    2011-04-01

    Modified 9Cr-1Mo ferritic steel is used as a structural material for steam generator components of power plants. Generally, tungsten inert gas (TIG) welding is preferred for welding of these steels in which the depth of penetration achievable during autogenous welding is limited. Therefore, activated flux TIG (A-TIG) welding, a novel welding technique, has been developed in-house to increase the depth of penetration. In modified 9Cr-1Mo steel joints produced by the A-TIG welding process, weld bead width, depth of penetration, and heat-affected zone (HAZ) width play an important role in determining the mechanical properties as well as the performance of the weld joints during service. To obtain the desired weld bead geometry and HAZ width, it becomes important to set the welding process parameters. In this work, adaptative neuro fuzzy inference system is used to develop independent models correlating the welding process parameters like current, voltage, and torch speed with weld bead shape parameters like depth of penetration, bead width, and HAZ width. Then a genetic algorithm is employed to determine the optimum A-TIG welding process parameters to obtain the desired weld bead shape parameters and HAZ width.

  16. Skull shapes of the Lissodelphininae: radiation, adaptation and asymmetry.

    PubMed

    Galatius, Anders; Goodall, R Natalie P

    2016-06-01

    Within Delphinidae, the sub-family Lissodelphininae consists of 8 Southern Ocean species and 2 North Pacific species. Lissodelphininae is a result of recent phylogenetic revisions based on molecular methods. Thus, morphological radiation within the taxon has not been investigated previously. The sub-family consists of ecologically diverse groups such as (1) the Cephalorhynchus genus of 4 small species inhabiting coastal and shelf waters, (2) the robust species in the Lagenorhynchus genus with the coastal La. australis, the offshore La. cruciger, the pelagic species La. obscurus and La. obliquidens, and (3) the morphologically aberrant genus Lissodelphis. Here, the shapes of 164 skulls from adults of all 10 species were compared using 3-dimensional geometric morphometrics. The Lissodelphininae skulls were supplemented by samples of Lagenorhynchus albirostris and Delphinus delphis to obtain a context for the variation found within the subfamily. Principal components analysis was used to map the most important components of shape variation on phylogeny. The first component of shape variation described an elongation of the rostrum, lateral and dorsoventral compression of the neurocranium and smaller temporal fossa. The two Lissodelphis species were on the high extreme of this spectrum, while Lagenorhynchus australis, La. cruciger and Cephalorhynchus heavisidii were at the low extreme. Along the second component, La. cruciger was isolated from the other species by its expanded neurocranium and concave facial profile. Shape variation supports the gross phylogenetic relationships proposed by recent molecular studies. However, despite the great diversity of ecology and external morphology within the subfamily, shape variation of the feeding apparatus was modest, indicating a similar mode of feeding across the subfamily. All 10 species were similar in their pattern of skull asymmetry, but interestingly, two species using narrowband high frequency clicks (La. cruciger and C

  17. Ecomorphological disparity in an adaptive radiation: opercular bone shape and stable isotopes in Antarctic icefishes

    PubMed Central

    Wilson, Laura A B; Colombo, Marco; Hanel, Reinhold; Salzburger, Walter; Sánchez-Villagra, Marcelo R

    2013-01-01

    To assess how ecological and morphological disparity is interrelated in the adaptive radiation of Antarctic notothenioid fish we used patterns of opercle bone evolution as a model to quantify shape disparity, phylogenetic patterns of shape evolution, and ecological correlates in the form of stable isotope values. Using a sample of 25 species including representatives from four major notothenioid clades, we show that opercle shape disparity is higher in the modern fauna than would be expected under the neutral evolution Brownian motion model. Phylogenetic comparative methods indicate that opercle shape data best fit a model of directional selection (Ornstein–Uhlenbeck) and are least supported by the “early burst” model of adaptive radiation. The main evolutionary axis of opercle shape change reflects movement from a broad and more symmetrically tapered opercle to one that narrows along the distal margin, but with only slight shape change on the proximal margin. We find a trend in opercle shape change along the benthic–pelagic axis, underlining the importance of this axis for diversification in the notothenioid radiation. A major impetus for the study of adaptive radiations is to uncover generalized patterns among different groups, and the evolutionary patterns in opercle shape among notothenioids are similar to those found among other adaptive radiations (three-spined sticklebacks) promoting the utility of this approach for assessing ecomorphological interactions on a broad scale. PMID:24102002

  18. Shape anomaly detection under strong measurement noise: An analytical approach to adaptive thresholding

    NASA Astrophysics Data System (ADS)

    Krasichkov, Alexander S.; Grigoriev, Eugene B.; Bogachev, Mikhail I.; Nifontov, Eugene M.

    2015-10-01

    We suggest an analytical approach to the adaptive thresholding in a shape anomaly detection problem. We find an analytical expression for the distribution of the cosine similarity score between a reference shape and an observational shape hindered by strong measurement noise that depends solely on the noise level and is independent of the particular shape analyzed. The analytical treatment is also confirmed by computer simulations and shows nearly perfect agreement. Using this analytical solution, we suggest an improved shape anomaly detection approach based on adaptive thresholding. We validate the noise robustness of our approach using typical shapes of normal and pathological electrocardiogram cycles hindered by additive white noise. We show explicitly that under high noise levels our approach considerably outperforms the conventional tactic that does not take into account variations in the noise level.

  19. Morphometry of anatomical shape complexes with dense deformations and sparse parameters.

    PubMed

    Durrleman, Stanley; Prastawa, Marcel; Charon, Nicolas; Korenberg, Julie R; Joshi, Sarang; Gerig, Guido; Trouvé, Alain

    2014-11-01

    We propose a generic method for the statistical analysis of collections of anatomical shape complexes, namely sets of surfaces that were previously segmented and labeled in a group of subjects. The method estimates an anatomical model, the template complex, that is representative of the population under study. Its shape reflects anatomical invariants within the dataset. In addition, the method automatically places control points near the most variable parts of the template complex. Vectors attached to these points are parameters of deformations of the ambient 3D space. These deformations warp the template to each subject's complex in a way that preserves the organization of the anatomical structures. Multivariate statistical analysis is applied to these deformation parameters to test for group differences. Results of the statistical analysis are then expressed in terms of deformation patterns of the template complex, and can be visualized and interpreted. The user needs only to specify the topology of the template complex and the number of control points. The method then automatically estimates the shape of the template complex, the optimal position of control points and deformation parameters. The proposed approach is completely generic with respect to any type of application and well adapted to efficient use in clinical studies, in that it does not require point correspondence across surfaces and is robust to mesh imperfections such as holes, spikes, inconsistent orientation or irregular meshing. The approach is illustrated with a neuroimaging study of Down syndrome (DS). The results demonstrate that the complex of deep brain structures shows a statistically significant shape difference between control and DS subjects. The deformation-based modelingis able to classify subjects with very high specificity and sensitivity, thus showing important generalization capability even given a low sample size. We show that the results remain significant even if the number of

  20. Morphometry of anatomical shape complexes with dense deformations and sparse parameters

    PubMed Central

    Durrleman, Stanley; Prastawa, Marcel; Charon, Nicolas; Korenberg, Julie R.; Joshi, Sarang; Gerig, Guido; Trouvé, Alain

    2016-01-01

    We propose a generic method for the statistical analysis of collections of anatomical shape complexes, namely sets of surfaces that were previously segmented and labeled in a group of subjects. The method estimates an anatomical model, the template complex, that is representative of the population under study. Its shape reflects anatomical invariants within the dataset. In addition, the method automatically places control points near the most variable parts of the template complex. Vectors attached to these points are parameters of deformations of the ambient 3D space. These deformations warp the template to each subject’s complex in a way that preserves the organization of the anatomical structures. Multivariate statistical analysis is applied to these deformation parameters to test for group differences. Results of the statistical analysis are then expressed in terms of deformation patterns of the template complex, and can be visualized and interpreted. The user needs only to specify the topology of the template complex and the number of control points. The method then automatically estimates the shape of the template complex, the optimal position of control points and deformation parameters. The proposed approach is completely generic with respect to any type of application and well adapted to efficient use in clinical studies, in that it does not require point correspondence across surfaces and is robust to mesh imperfections such as holes, spikes, inconsistent orientation or irregular meshing. The approach is illustrated with a neuroimaging study of Down syndrome (DS). Results demonstrate that the complex of deep brain structures shows a statistically significant shape difference between control and DS subjects. The deformation-based modeling is able to classify subjects with very high specificity and sensitivity, thus showing important generalization capability even given a low sample size. We show that results remain significant even if the number of

  1. Neighboring genes shaping a single adaptive mimetic trait.

    PubMed

    Pardo-Diaz, Carolina; Jiggins, Chris D

    2014-01-01

    The colorful wing patterns of Heliconius butterflies represent an excellent system in which to study the genetic and developmental control of adaptation and convergence. Using qRT-PCR and in situ hybridization on developing wings of the co-mimic species Heliconius melpomene and Heliconius erato, we have profiled the expression of three candidate genes located in the genomic locus controlling red color pattern variation. We found convergent domains of gene expression in H. melpomene and H. erato associated with red wing elements in the two genes optix and kinesin. During early pupal development of both species, the expression of optix perfectly associated with all red pattern elements whereas that of kinesin was specifically correlated with the presence of the red forewing band. These results provide evidence for the use of these two tightly linked patterning genes, acting together to create convergent wing phenotypes in Heliconius and constituting a hotspot of adaptation. PMID:24393463

  2. Adaptive Matching of the Scanning Aperture of the Environment Parameter

    NASA Astrophysics Data System (ADS)

    Choni, Yu. I.; Yunusov, N. N.

    2016-04-01

    We analyze a matching system for the scanning aperture antenna radiating through a layer with unpredictably changing parameters. Improved matching has been achieved by adaptive motion of a dielectric plate in the gap between the aperture and the radome. The system is described within the framework of an infinite layered structure. The validity of the model has been confirmed by numerical simulation using CST Microwave Studio software and by an experiment. It is shown that the reflection coefficient at the input of some types of a matching device, which is due to the deviation of the load impedance from the nominal value, is determined by a compact and versatile formula. The potential efficiency of the proposed matching system is shown by a specific example, and its dependence on the choice of the starting position of the dielectric plate is demonstrated.

  3. Adaptive Matching of the Scanning Aperture of the Environment Parameter

    NASA Astrophysics Data System (ADS)

    Choni, Yu. I.; Yunusov, N. N.

    2016-05-01

    We analyze a matching system for the scanning aperture antenna radiating through a layer with unpredictably changing parameters. Improved matching has been achieved by adaptive motion of a dielectric plate in the gap between the aperture and the radome. The system is described within the framework of an infinite layered structure. The validity of the model has been confirmed by numerical simulation using CST Microwave Studio software and by an experiment. It is shown that the reflection coefficient at the input of some types of a matching device, which is due to the deviation of the load impedance from the nominal value, is determined by a compact and versatile formula. The potential efficiency of the proposed matching system is shown by a specific example, and its dependence on the choice of the starting position of the dielectric plate is demonstrated.

  4. Adaptive electron beam shaping using a photoemission gun and spatial light modulator

    NASA Astrophysics Data System (ADS)

    Maxson, Jared; Lee, Hyeri; Bartnik, Adam C.; Kiefer, Jacob; Bazarov, Ivan

    2015-02-01

    The need for precisely defined beam shapes in photoelectron sources has been well established. In this paper, we use a spatial light modulator and simple shaping algorithm to create arbitrary, detailed transverse laser shapes with high fidelity. We transmit this shaped laser to the photocathode of a high voltage dc gun. Using beam currents where space charge is negligible, and using an imaging solenoid and fluorescent viewscreen, we show that the resultant beam shape preserves these detailed features with similar fidelity. Next, instead of transmitting a shaped laser profile, we use an active feedback on the unshaped electron beam image to create equally accurate and detailed shapes. We demonstrate that this electron beam feedback has the added advantage of correcting for electron optical aberrations, yielding shapes without skew. The method may serve to provide precisely defined electron beams for low current target experiments, space-charge dominated beam commissioning, as well as for online adaptive correction of photocathode quantum efficiency degradation.

  5. Altered Visual Adaptation to Body Shape in Eating Disorders: Implications for Body Image Distortion.

    PubMed

    Mohr, Harald M; Rickmeyer, Constanze; Hummel, Dennis; Ernst, Mareike; Grabhorn, Ralph

    2016-07-01

    Previous research has shown that after adapting to a thin body, healthy participants (HP) perceive pictures of their own bodies as being fatter and vice versa. This aftereffect might contribute to the development of perceptual body image disturbances in eating disorders (ED).In the present study, HP and ED completed a behavioral experiment to rate manipulated pictures of their own bodies after adaptation to thin or fat body pictures. After adapting to a thin body, HP judged a thinner than actual body picture to be the most realistic and vice versa, resembling a typical aftereffect. ED only showed such an adaptation effect when they adapted to fat body pictures.The reported results indicate a relationship between body image distortion in ED and visual body image adaptation. It can be suspected that due to a pre-existing, long-lasting adaptation to thin body shapes in ED, an additional visual adaption to thin body shapes cannot be induced. Hence this pre-existing adaptation to thin body shapes could induce perceptual body image distortions in ED. PMID:26921409

  6. Estimation of cosmological parameters using adaptive importance sampling

    SciTech Connect

    Wraith, Darren; Kilbinger, Martin; Benabed, Karim; Prunet, Simon; Cappe, Olivier; Fort, Gersende; Cardoso, Jean-Francois; Robert, Christian P.

    2009-07-15

    We present a Bayesian sampling algorithm called adaptive importance sampling or population Monte Carlo (PMC), whose computational workload is easily parallelizable and thus has the potential to considerably reduce the wall-clock time required for sampling, along with providing other benefits. To assess the performance of the approach for cosmological problems, we use simulated and actual data consisting of CMB anisotropies, supernovae of type Ia, and weak cosmological lensing, and provide a comparison of results to those obtained using state-of-the-art Markov chain Monte Carlo (MCMC). For both types of data sets, we find comparable parameter estimates for PMC and MCMC, with the advantage of a significantly lower wall-clock time for PMC. In the case of WMAP5 data, for example, the wall-clock time scale reduces from days for MCMC to hours using PMC on a cluster of processors. Other benefits of the PMC approach, along with potential difficulties in using the approach, are analyzed and discussed.

  7. Finite Element Analysis of Adaptive-Stiffening and Shape-Control SMA Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Gao, Xiujie; Burton, Deborah; Turner, Travis L.; Brinson, Catherine

    2005-01-01

    Shape memory alloy hybrid composites with adaptive-stiffening or morphing functions are simulated using finite element analysis. The composite structure is a laminated fiber-polymer composite beam with embedded SMA ribbons at various positions with respect to the neutral axis of the beam. Adaptive stiffening or morphing is activated via selective resistance heating of the SMA ribbons or uniform thermal loads on the beam. The thermomechanical behavior of these composites was simulated in ABAQUS using user-defined SMA elements. The examples demonstrate the usefulness of the methods for the design and simulation of SMA hybrid composites. Keywords: shape memory alloys, Nitinol, ABAQUS, finite element analysis, post-buckling control, shape control, deflection control, adaptive stiffening, morphing, constitutive modeling, user element

  8. Investigation of the Gamma Distribution Shape Parameter in Shallow Cumulus Clouds

    NASA Astrophysics Data System (ADS)

    Igel, A. L.; van den Heever, S. C.

    2014-12-01

    Many bulk microphysics parameterizations assume that the droplet size distribution (DSD) of hydrometeor species such as cloud water and rain water conform to a gamma probability distribution function (PDF). Such an assumption is necessary in order to simplify the description of microphysical processes in such bulk parameterizations. The gamma PDF has a parameter that influences the width of the distribution that is commonly referred to as the shape parameter. In one- and two-moment bulk microphysics schemes, this parameter is often arbitrarily set to a fixed value throughout the simulation. This is in part due to limited observations of the shape parameter. While many studies have sought to understand this parameter for rain, few studies examine this parameter for cloud droplets. In this study, we use high-resolution simulations of shallow cumulus clouds with a spectral bin representation of the hydrometeor species to find best-fit parameters of the gamma PDF to the predicted cloud DSDs. These simulations reveal that the cloud shape parameter is high in the supersaturated regions of the cloud and low in regions where the cloud water is evaporating. Values many times higher than the standard values of 1-4 are not uncommon in the bin simulations. The results of this analysis are used to suggest appropriate values of the cloud shape parameter in simulations employing a bulk microphysics scheme. The sensitivity of cloud properties, dynamics, and rainfall to the cloud shape parameter are investigated in simulations in which the parameter is fixed. Conclusions about the importance of choosing an appropriate cloud shape parameter for simulating cumulus clouds in climate or weather models are drawn.

  9. Neural adaptation to non-symbolic number and visual shape: an electrophysiological study.

    PubMed

    Soltész, Fruzsina; Szűcs, Dénes

    2014-12-01

    Several studies assumed that the analysis of numerical information happens in a fast and automatic manner in the human brain. Utilizing the high temporal resolution of electroencephalography (EEG) in a passive oddball adaptation paradigm, we compared event-related brain potentials (ERPs) evoked by unattended shape changes and unattended numerosity changes. We controlled visual stimulus properties in a stringent manner. Unattended changes in shape elicited significant, gradual adaptation effects in the range of early visual components, indicating the fast and automatic processing of shapes. Changes in numerosity did not elicit significant changes in these early ERP components. The lack of early number-specific effects was qualified by a significant interaction between Shape and Number conditions. Number change elicited gradual ERP effects only on late ERP components. We conclude that numerosity is a higher-level property assembled from naturally correlating perceptual cues and hence, it is identified later in the cognitive processing stream. PMID:25258032

  10. Adaptive Multichannel Radiation Sensors for Plant Parameter Monitoring

    NASA Astrophysics Data System (ADS)

    Mollenhauer, Hannes; Remmler, Paul; Schuhmann, Gudrun; Lausch, Angela; Merbach, Ines; Assing, Martin; Mollenhauer, Olaf; Dietrich, Peter; Bumberger, Jan

    2016-04-01

    Nutrients such as nitrogen are playing a key role in the plant life cycle. They are much needed for chlorophyll production and other plant cell components. Therefore, the crop yield is strongly affected by plant nutrient status. Due to the spatial and temporal variability of soil characteristics or swaying agricultural inputs the plant development varies within a field. Thus, the determination of these fluctuations in the plant development is valuable for a detection of stress conditions and optimization of fertilisation due to its high environmental and economic impact. Plant parameters play crucial roles in plant growth estimation and prediction since they are used as indicators of plant performance. Especially indices derived out of remote sensing techniques provide quantitative information about agricultural crops instantaneously, and above all, non-destructively. Due to the specific absorption of certain plant pigments, a characteristic spectral signature can be seen in the visible and IR part of the electromagnetic spectrum, known as narrow-band peaks. In an analogous manner, the presence and concentration of different nutrients cause a characteristic spectral signature. To this end, an adequate remote sensing monitoring concept is needed, considering heterogeneity and dynamic of the plant population and economical aspects. This work will present the development and field investigations of an inexpensive multichannel radiation sensor to observe the incoming and reflected specific parts or rather distinct wavelengths of the solar light spectrum on the crop and facilitate the determination of different plant indices. Based on the selected sensor wavelengths, the sensing device allows the detection of specific parameters, e.g. plant vitality, chlorophyll content or nitrogen content. Besides the improvement of the sensor characteristic, the simple wavelength adaption, and the price-performance ratio, the achievement of appropriate energy efficiency as well as a

  11. Generalized synchronization with uncertain parameters of nonlinear dynamic system via adaptive control.

    PubMed

    Yang, Cheng-Hsiung; Wu, Cheng-Lin

    2014-01-01

    An adaptive control scheme is developed to study the generalized adaptive chaos synchronization with uncertain chaotic parameters behavior between two identical chaotic dynamic systems. This generalized adaptive chaos synchronization controller is designed based on Lyapunov stability theory and an analytic expression of the adaptive controller with its update laws of uncertain chaotic parameters is shown. The generalized adaptive synchronization with uncertain parameters between two identical new Lorenz-Stenflo systems is taken as three examples to show the effectiveness of the proposed method. The numerical simulations are shown to verify the results. PMID:25295292

  12. Adaptive Square-Shaped Trajectory-Based Service Location Protocol in Wireless Sensor Networks

    PubMed Central

    Lim, Hwa-Jung; Lee, Joa-Hyoung; Lee, Heon-Guil

    2010-01-01

    In this paper we propose an adaptive square-shaped trajectory (ASST)-based service location method to ensure load scalability in wireless sensor networks. This first establishes a square-shaped trajectory over the nodes that surround a target point computed by the hash function and any user can access it, using the hash. Both the width and the size of the trajectory are dynamically adjustable, depending on the number of queries made to the service information on the trajectory. The number of sensor nodes on the trajectory varies in proportion to the changing trajectory shape, allowing high loads to be distributed around the hot spot area. PMID:22399889

  13. A Shape Memory Polymer Dialysis Needle Adapter for the Reduction of Hemodynamic Stress within Arteriovenous Grafts

    SciTech Connect

    Ortega, J M; Small, W; Wilson, T S; Benett, W; Loge, J; Maitland, D J

    2006-08-16

    A deployable, shape memory polymer adapter is investigated for reducing the hemodynamic stress caused by a dialysis needle flow within an arteriovenous graft. Computational fluid dynamics simulations of dialysis sessions with and without the adapter demonstrate that the adapter provides a significant decrease in the wall shear stress. In vitro flow visualization measurements are made within a graft model following delivery and actuation of a prototype shape memory polymer adapter. Vascular access complications resulting from arteriovenous (AV) graft failures account for over $1 billion per year in the health care costs of dialysis patients in the U.S.[1] The primary mode of failure of arteriovenous fistulas (AVF's) and polytetrafluoroethylene (PTFE) grafts is the development of intimal hyperplasia (IH) and the subsequent formation of stenotic lesions, resulting in a graft flow decline. The hemodynamic stresses arising within AVF's and PTFE grafts play an important role in the pathogenesis of IH. Studies have shown that vascular damage can occur in regions where there is flow separation, oscillation, or extreme values of wall shear stress (WSS).[2] Nevaril et al.[3] show that exposure of red blood cells to WSS's on the order of 1500 dynes/cm2 can result in hemolysis. Hemodynamic stress from dialysis needle flow has recently been investigated for the role it plays in graft failure. Using laser Doppler velocimetry measurements, Unnikrishnan et al.[4] show that turbulence intensities are 5-6 times greater in the AV flow when the needle flow is present and that increased levels of turbulence exist for approximately 7-8cm downstream of the needle. Since the AVF or PTFE graft is exposed to these high levels of hemodynamic stress several hours each week during dialysis sessions, it is quite possible that needle flow is an important contributor to vascular access occlusion.[4] We present a method for reducing the hemodynamic stress in an AV graft by tailoring the fluid

  14. Population diversity and adaptive evolution in keratinization genes: impact of environment in shaping skin phenotypes.

    PubMed

    Gautam, Pramod; Chaurasia, Amit; Bhattacharya, Aniket; Grover, Ritika; Mukerji, Mitali; Natarajan, Vivek T

    2015-03-01

    Several studies have demonstrated the role of climatic factors in shaping skin phenotypes, particularly pigmentation. Keratinization is another well-designed feature of human skin, which is involved in modulating transepidermal water loss (TEWL). Although this physiological process is closely linked to climate, presently it is not clear whether genetic diversity is observed in keratinization and whether this process also responds to the environmental pressure. To address this, we adopted a multipronged approach, which involved analysis of 1) copy number variations in diverse Indian and HapMap populations from varied geographical regions; 2) genetic association with geoclimatic parameters in 61 populations of dbCLINE database in a set of 549 genes from four processes namely keratinization, pigmentation, epidermal differentiation, and housekeeping functions; 3) sequence divergence in 4,316 orthologous promoters and corresponding exonic regions of human and chimpanzee with macaque as outgroup, and 4) protein sequence divergence (Ka/Ks) across nine vertebrate classes, which differ in their extent of TEWL. Our analyses demonstrate that keratinization and epidermal differentiation genes are under accelerated evolution in the human lineage, relative to pigmentation and housekeeping genes. We show that this entire pathway may have been driven by environmental selection pressure through concordant functional polymorphisms across several genes involved in skin keratinization. Remarkably, this underappreciated function of skin may be a crucial determinant of adaptation to diverse environmental pressures across world populations. PMID:25534032

  15. Conservatism and Adaptability during Squirrel Radiation: What Is Mandible Shape Telling Us?

    PubMed Central

    Casanovas-Vilar, Isaac; van Dam, Jan

    2013-01-01

    Both functional adaptation and phylogeny shape the morphology of taxa within clades. Herein we explore these two factors in an integrated way by analyzing shape and size variation in the mandible of extant squirrels using landmark-based geometric morphometrics in combination with a comparative phylogenetic analysis. Dietary specialization and locomotion were found to be reliable predictors of mandible shape, with the prediction by locomotion probably reflecting the underlying diet. In addition a weak but significant allometric effect could be demonstrated. Our results found a strong phylogenetic signal in the family as a whole as well as in the main clades, which is in agreement with the general notion of squirrels being a conservative group. This fact does not preclude functional explanations for mandible shape, but rather indicates that ancient adaptations kept a prominent role, with most genera having diverged little from their ancestral clade morphologies. Nevertheless, certain groups have evolved conspicuous adaptations that allow them to specialize on unique dietary resources. Such adaptations mostly occurred in the Callosciurinae and probably reflect their radiation into the numerous ecological niches of the tropical and subtropical forests of Southeastern Asia. Our dietary reconstruction for the oldest known fossil squirrels (Eocene, 36 million years ago) show a specialization on nuts and seeds, implying that the development from protrogomorphous to sciuromorphous skulls was not necessarily related to a change in diet. PMID:23593456

  16. The reduced order model problem in distributed parameter systems adaptive identification and control

    NASA Technical Reports Server (NTRS)

    Johnson, C. R., Jr.

    1980-01-01

    The research concerning the reduced order model problem in distributed parameter systems is reported. The adaptive control strategy was chosen for investigation in the annular momentum control device. It is noted, that if there is no observation spill over, and no model errors, an indirect adaptive control strategy can be globally stable. Recent publications concerning adaptive control are included.

  17. Adaptive synchronization of a class of continuous chaotic systems with uncertain parameters

    NASA Astrophysics Data System (ADS)

    Zhang, Gang; Liu, Zengrong; Zhang, Jianbao

    2008-01-01

    This Letter investigates the problem of synchronization between two different chaotic systems. A generic adaptive synchronization scheme is proposed for a class of chaotic systems with uncertain parameters. Based on the Lyapunov stability theorem, an adaptive controller and the corresponding parameters update laws are designed to synchronize two chaotic systems. Numerical simulations are also given to show the effectiveness of the proposed method.

  18. Adaptation to shape switching by component selection in a constitutional dynamic system.

    PubMed

    Ulrich, Sébastien; Lehn, Jean-Marie

    2009-04-22

    Molecules having different accessible shape states, which can be addressed in an effector-controlled manner, may be termed morphological switches. A dynamic covalent system can undergo adaptation to each state of a two-state morphological switch by generation of an optimal constitution through component selection. We have studied such a component selection in the dynamic covalent constituents generated by metal cation-induced shape switching of a core component between two states of W and U shape, characterized by both different geometries and different coordination features. The system performs shape-dependent self-sorting of metal ions and components. The origin of the selectivity was investigated through competition experiments, in solution and by analysis of solid state structures, which reveal the role of the molecular shape in the formation of a particular self-assembled architecture. The coordination features of each state as well as phase change also play an important role, in addition to the shape plasticity, in steering the covalent dynamic system toward the formation of a given entity by the selection of the most appropriate components. Different examples are described which show that the morphological switching of one component of a given self-assembled entity can lead to the exchange of the complementary one, which is no longer the best partner, for a new partner, able to form a more stable new assembly. Thus, the constitutional evolution of these dynamic systems is steered by the shape of a given state via both its geometry and its coordination features toward metal ions, leading to incorporation/decorporation of the most appropriate components. The controlled interconversion of the shape states of the morphological switches, induced by addition/removal of metal ions, results in a constitutional adaptation behavior through inversion of the selection preferences. PMID:19206535

  19. Finite Element Analysis of Adaptive-Stiffening and Shape-Control SMA Hybrid Composites

    NASA Technical Reports Server (NTRS)

    Gao, Xiu-Jie; Turner, Travis L.; Burton, Deborah; Brinson, L. Catherine

    2005-01-01

    The usage of shape memory materials has extended rapidly to many fields, including medical devices, actuators, composites, structures and MEMS devices. For these various applications, shape memory alloys (SMAs) are available in various forms: bulk, wire, ribbon, thin film, and porous. In this work, the focus is on SMA hybrid composites with adaptive-stiffening or morphing functions. These composites are created by using SMA ribbons or wires embedded in a polymeric based composite panel/beam. Adaptive stiffening or morphing is activated via selective resistance heating or uniform thermal loads. To simulate the thermomechanical behavior of these composites, a SMA model was implemented using ABAQUS user element interface and finite element simulations of the systems were studied. Several examples are presented which show that the implemented model can be a very useful design and simulation tool for SMA hybrid composites.

  20. Statistical inference methods for recurrent event processes with shape and size parameters

    PubMed Central

    WANG, MEI-CHENG; HUANG, CHIUNG-YU

    2015-01-01

    Summary This paper proposes a unified framework to characterize the rate function of a recurrent event process through shape and size parameters. In contrast to the intensity function, which is the event occurrence rate conditional on the event history, the rate function is the occurrence rate unconditional on the event history, and thus it can be interpreted as a population-averaged count of events in unit time. In this paper, shape and size parameters are introduced and used to characterize the association between the rate function λ(·) and a random variable X. Measures of association between X and λ(·) are defined via shape- and size-based coefficients. Rate-independence of X and λ(·) is studied through tests of shape-independence and size-independence, where the shape-and size-based test statistics can be used separately or in combination. These tests can be applied when X is a covariable possibly correlated with the recurrent event process through λ(·) or, in the one-sample setting, when X is the censoring time at which the observation of N(·) is terminated. The proposed tests are shape- and size-based, so when a null hypothesis is rejected, the test results can serve to distinguish the source of violation. PMID:26412863

  1. Simultaneous optimization of actuator position and control parameter for adaptive mechanical structures

    NASA Astrophysics Data System (ADS)

    Weber, Christian-Toralf; Gabbert, Ulrich; Enzmann, Marc R.

    1998-07-01

    The design of adaptive mechanical structures is divided into three parts: the structural design, the controller design and the placement of actuators and sensors. The objective of the design is to create a mechanical structure, which corresponds with the physical and technical requirements. The controller design includes the definition of the optimal controller law and the parameters required to create an actuator adjustment from the perceptible signals of the structural answer. The placement of the actuators and of the sensors give an answer to the question about the optimal distribution of the actuators and sensors in the structure. The sensor placement determines which signals are available to the automatic controller. The position of the actuators in the mechanical structure determines at which points control forces may act to influence the structural behavior in a suitable manner. The determination of the optimal position of the actuators require information about the controller design, the sensor position and the layout and the behavior of the structure. Based on the ideas of the shape optimization and topology optimization, a procedure will be presented, to handle simultaneously the discrete positions of the actuators and the continuous parameters of the controller. The method is based on an augmented Lagrangian function to include additional conditions and the discontinuity of the discrete variables into the objective function. The method will be demonstrated by an test example.

  2. Local adaptation with high gene flow: temperature parameters drive adaptation to altitude in the common frog (Rana temporaria)

    PubMed Central

    Muir, A P; Biek, R; Thomas, R; Mable, B K

    2014-01-01

    Both environmental and genetic influences can result in phenotypic variation. Quantifying the relative contributions of local adaptation and phenotypic plasticity to phenotypes is key to understanding the effect of environmental variation on populations. Identifying the selective pressures that drive divergence is an important, but often lacking, next step. High gene flow between high- and low-altitude common frog (Rana temporaria) breeding sites has previously been demonstrated in Scotland. The aim of this study was to assess whether local adaptation occurs in the face of high gene flow and to identify potential environmental selection pressures that drive adaptation. Phenotypic variation in larval traits was quantified in R. temporaria from paired high- and low-altitude sites using three common temperature treatments. Local adaptation was assessed using QST–FST analyses, and quantitative phenotypic divergence was related to environmental parameters using Mantel tests. Although evidence of local adaptation was found for all traits measured, only variation in larval period and growth rate was consistent with adaptation to altitude. Moreover, this was only evident in the three mountains with the highest high-altitude sites. This variation was correlated with mean summer and winter temperatures, suggesting that temperature parameters are potentially strong selective pressures maintaining local adaptation, despite high gene flow. PMID:24330274

  3. Semianalytic theory of self-similar optical propagation and mode locking using a shape-adaptive model pulse

    SciTech Connect

    Jirauschek, Christian; Ilday, F. Oemer

    2011-06-15

    A semianalytic theory for the pulse dynamics in similariton amplifiers and lasers is presented, based on a model pulse with adaptive shape. By changing a single parameter, this test function can be continuously tweaked between a pure Gaussian and a pure parabolic profile and can even represent sech-like pulses, the shape of a soliton. This approach allows us to describe the pulse evolution in the self-similar and other regimes of optical propagation. Employing the method of moments, the evolution equations for the characteristic pulse parameters are derived from the governing nonlinear Schroedinger or Ginzburg-Landau equation. Due to its greatly reduced complexity, this description allows for extensive parameter optimization, and can aid intuitive understanding of the dynamics. As an application of this approach, we model a soliton-similariton laser and validate the results against numerical simulations. This constitutes a semianalytic model of the soliton-similariton laser. Due to the versatility of the model pulse, it can also prove useful in other application areas.

  4. Comparison of Two Methods Used to Model Shape Parameters of Pareto Distributions

    USGS Publications Warehouse

    Liu, C.; Charpentier, R.R.; Su, J.

    2011-01-01

    Two methods are compared for estimating the shape parameters of Pareto field-size (or pool-size) distributions for petroleum resource assessment. Both methods assume mature exploration in which most of the larger fields have been discovered. Both methods use the sizes of larger discovered fields to estimate the numbers and sizes of smaller fields: (1) the tail-truncated method uses a plot of field size versus size rank, and (2) the log-geometric method uses data binned in field-size classes and the ratios of adjacent bin counts. Simulation experiments were conducted using discovered oil and gas pool-size distributions from four petroleum systems in Alberta, Canada and using Pareto distributions generated by Monte Carlo simulation. The estimates of the shape parameters of the Pareto distributions, calculated by both the tail-truncated and log-geometric methods, generally stabilize where discovered pool numbers are greater than 100. However, with fewer than 100 discoveries, these estimates can vary greatly with each new discovery. The estimated shape parameters of the tail-truncated method are more stable and larger than those of the log-geometric method where the number of discovered pools is more than 100. Both methods, however, tend to underestimate the shape parameter. Monte Carlo simulation was also used to create sequences of discovered pool sizes by sampling from a Pareto distribution with a discovery process model using a defined exploration efficiency (in order to show how biased the sampling was in favor of larger fields being discovered first). A higher (more biased) exploration efficiency gives better estimates of the Pareto shape parameters. ?? 2011 International Association for Mathematical Geosciences.

  5. Invisible cloak design with controlled constitutive parameters and arbitrary shaped boundaries through Helmholtz's equation.

    PubMed

    Chen, Xi; Fu, Yunqi; Yuan, Naichang

    2009-03-01

    An approach to design an invisible cloak with controlled constitutive parameters and arbitrary shaped boundaries is presented. Helmholtz's equation is adopted to establish a mapping between original and transformed coordinates inside the cloak. Then the constitutive parameters are obtained by the established mapping. The analytical solution of a regular cloak and the numerical solution of an irregular cloak both verify that that our method will guide electromagnetic wave efficiently and control the constitutive parameters of the cloak conveniently. It has great significance in realizing a cloak practically. PMID:19259197

  6. Time course of shape and category selectivity revealed by EEG rapid adaptation.

    PubMed

    Scholl, Clara A; Jiang, Xiong; Martin, Jacob G; Riesenhuber, Maximilian

    2014-02-01

    A hallmark of human cognition is the ability to rapidly assign meaning to sensory stimuli. It has been suggested that this fast visual object categorization ability is accomplished by a feedforward processing hierarchy consisting of shape-selective neurons in occipito-temporal cortex that feed into task circuits in frontal cortex computing conceptual category membership. We performed an EEG rapid adaptation study to test this hypothesis. Participants were trained to categorize novel stimuli generated with a morphing system that precisely controlled both stimulus shape and category membership. We subsequently performed EEG recordings while participants performed a category matching task on pairs of successively presented stimuli. We used space-time cluster analysis to identify channels and latencies exhibiting selective neural responses. Neural signals before 200 msec on posterior channels demonstrated a release from adaptation for shape changes, irrespective of category membership, compatible with a shape- but not explicitly category-selective neural representation. A subsequent cluster with anterior topography appeared after 200 msec and exhibited release from adaptation consistent with explicit categorization. These signals were subsequently modulated by perceptual uncertainty starting around 300 msec. The degree of category selectivity of the anterior signals was strongly predictive of behavioral performance. We also observed a posterior category-selective signal after 300 msec exhibiting significant functional connectivity with the initial anterior category-selective signal. In summary, our study supports the proposition that perceptual categorization is accomplished by the brain within a quarter second through a largely feedforward process culminating in frontal areas, followed by later category-selective signals in posterior regions. PMID:24001003

  7. Experimental evaluation of a shape memory alloy wire actuator with a modulated adaptive controller for position control

    NASA Astrophysics Data System (ADS)

    Senthilkumar, P.; Dayananda, G. N.; Umapathy, M.; Shankar, V.

    2012-01-01

    This paper presents an experimental investigation of position control of a shape memory alloy (SMA) wire actuator with adaptive and modulated adaptive controllers. The transfer function model of the SMA wire actuator is determined from the experimental open loop response. Adaptive controllers, namely LMS-GSPI, RLS-GSPI and Kalman-GSPI, and modulated adaptive controllers using pulse width modulation (PWM) are designed. The performances of these controllers are experimentally investigated for the position control of an SMA wire actuator with and without thermal disturbance. Experimental results demonstrate that the modulated adaptive controllers outperform adaptive controllers.

  8. Fuzzy Backstepping Torque Control Of Passive Torque Simulator With Algebraic Parameters Adaptation

    NASA Astrophysics Data System (ADS)

    Ullah, Nasim; Wang, Shaoping; Wang, Xingjian

    2015-07-01

    This work presents fuzzy backstepping control techniques applied to the load simulator for good tracking performance in presence of extra torque, and nonlinear friction effects. Assuming that the parameters of the system are uncertain and bounded, Algebraic parameters adaptation algorithm is used to adopt the unknown parameters. The effect of transient fuzzy estimation error on parameters adaptation algorithm is analyzed and the fuzzy estimation error is further compensated using saturation function based adaptive control law working in parallel with the actual system to improve the transient performance of closed loop system. The saturation function based adaptive control term is large in the transient time and settles to an optimal lower value in the steady state for which the closed loop system remains stable. The simulation results verify the validity of the proposed control method applied to the complex aerodynamics passive load simulator.

  9. Disability Parameters, Chronic Strain, and Adaptation of Physically Handicapped Children and Their Mothers.

    ERIC Educational Resources Information Center

    Wallander, Jan L.; And Others

    1989-01-01

    The study investigated the contribution of disability parameters and chronic disability-related strain to the adaptation of 50 children (6 to 11 years old) with congenital physical disabilities and their mothers. Adaptation (except for the children's social functioning) was not significantly related to either the child's disability status nor the…

  10. Adaptive neuro-fuzzy estimation of optimal lens system parameters

    NASA Astrophysics Data System (ADS)

    Petković, Dalibor; Pavlović, Nenad T.; Shamshirband, Shahaboddin; Mat Kiah, Miss Laiha; Badrul Anuar, Nor; Idna Idris, Mohd Yamani

    2014-04-01

    Due to the popularization of digital technology, the demand for high-quality digital products has become critical. The quantitative assessment of image quality is an important consideration in any type of imaging system. Therefore, developing a design that combines the requirements of good image quality is desirable. Lens system design represents a crucial factor for good image quality. Optimization procedure is the main part of the lens system design methodology. Lens system optimization is a complex non-linear optimization task, often with intricate physical constraints, for which there is no analytical solutions. Therefore lens system design provides ideal problems for intelligent optimization algorithms. There are many tools which can be used to measure optical performance. One very useful tool is the spot diagram. The spot diagram gives an indication of the image of a point object. In this paper, one optimization criterion for lens system, the spot size radius, is considered. This paper presents new lens optimization methods based on adaptive neuro-fuzzy inference strategy (ANFIS). This intelligent estimator is implemented using Matlab/Simulink and the performances are investigated.

  11. Flight test experience with an adaptive control system using a maximum likelihood parameter estimation technique

    NASA Technical Reports Server (NTRS)

    Hartmann, G.; Stein, G.; Powers, B.

    1979-01-01

    The flight test performance of an adaptive control system for the F-8 DFBW aircraft is summarized. The adaptive system is based on explicit identification of surface effectiveness parameters which are used for gain scheduling in a command augmentation system. Performance of this control law under various design parameter variations is presented. These include variations in test signal level, sample rate, and identification channel structure. Flight performance closely matches analysis and simulation predictions from previous references.

  12. Experimental evaluation of shape memory alloy actuation technique in adaptive antenna design concepts

    NASA Technical Reports Server (NTRS)

    Kefauver, W. Neill; Carpenter, Bernie F.

    1994-01-01

    Creation of an antenna system that could autonomously adapt contours of reflecting surfaces to compensate for structural loads induced by a variable environment would maximize performance of space-based communication systems. Design of such a system requires the comprehensive development and integration of advanced actuator, sensor, and control technologies. As an initial step in this process, a test has been performed to assess the use of a shape memory alloy as a potential actuation technique. For this test, an existing, offset, cassegrain antenna system was retrofit with a subreflector equipped with shape memory alloy actuators for surface contour control. The impacts that the actuators had on both the subreflector contour and the antenna system patterns were measured. The results of this study indicate the potential for using shape memory alloy actuation techniques to adaptively control antenna performance; both variations in gain and beam steering capabilities were demonstrated. Future development effort is required to evolve this potential into a useful technology for satellite applications.

  13. Particle Shape: A New Design Parameter for Micro- and Nanoscale Drug Delivery Carriers

    PubMed Central

    Champion, Julie A.; Katare, Yogesh K.; Mitragotri, Samir

    2014-01-01

    Encapsulation of therapeutic agents in polymer particles has been successfully used in the development of new drug carriers. A number of design parameters that govern the functional behavior of carriers, including the choice of polymer, particle size and surface chemistry, have been tuned to optimize their performance in vivo. However, particle shape, which may also have a strong impact on carrier performance, has not been investigated. This is perhaps due to the limited availability of techniques to produce non-spherical polymer particles. In recent years, a number of reports have emerged to directly address this bottleneck and initial studies have indeed confirmed that particle shape can significantly impact the performance of polymer drug carriers. This article provides a review of this field with respect to methods of particle preparation and the role of particle shape in drug delivery. PMID:17544538

  14. The influence of thin-film heater shape parameters on the electromigration

    NASA Astrophysics Data System (ADS)

    Huang, Fei; Ding, Shanting; Li, Huajing

    2016-01-01

    Au heater is one of the core components of thermo optic effect devices. The reliability of Au heaters affects the lifetime of whole devices directly. In order to explore the influence of shape parameters on lifetime of Au heater, the accelerate life test (ALT) was designed and conducted. Samples with different shape parameters were prepared for the ALT in which the applied current was 500mA and the test temperature was 150°C. The results showed that failure mode of all the different samples was open circuit. The electromigration was found the reason for this kind of failure in test conditions. According to the experimental and finite element simulating results, the fusing break appeared in the transition arc area where temperature gradient was the maximum. It is also can be found that the larger the radius, the later the failure. In other words, lifetime of the thin-film heater with larger transition radius was longer.

  15. Parameter exploration of staircase-shape extracellular stimulation for targeted stimulation of myelinated axon.

    PubMed

    Ueno, Ayako; Karashima, Akihiro; Nakao, Mitsuyuki; Katayama, Norihiro

    2011-01-01

    Spatio-temporal dynamics of a mathematical model of myelinated axon in response to staircase-shape extracellular electrical stimulation, which was developed for selective nerve stimulation, is investigated by the computer simulation. It is shown that the response is classified into four types: subthreshold response, cathodic excitation, anodal block and anodal break excitation. Based on the simulation results, simple diagrams representing the response characteristics of the axon are constructed as functions of stimulation parameters and distance between the axon and electrode. The diagram would be useful for determining simulation parameters for dynamic targeted stimulation of myelinated axon. PMID:22254459

  16. Parameter for the vertical-position control of dee-shaped plasmas in Doublet III

    SciTech Connect

    Yokomizo, H.; Seki, S.; Shimada, M.; Nagami, M.; Konoshima, S.; Fujisawa, N.; Ohara, Y.; Ioki, K.; Kitsunezaki, A.

    1981-06-01

    A simple method has been developed using three magnetic probes to detect the vertical position of the center of dee-shaped plasmas located in the upper lobe of Doublet III. This parameter has no dependence on the plasma current and only a small dependence on the horizontal (radial) position of the plasma column. The comparison between the new parameter and the result of MHD calculation shows good correlation with the vertical position of the plasma center. This provides an effective means for improving control of the plasma position and maintaining stable dee plasmas.

  17. Adaptive control of lasers and their interactions with matter using femtosecond pulse shaping

    NASA Astrophysics Data System (ADS)

    Efimov, Anatoly

    Coherent control of chemical reactions, atomic and molecular systems, lattice dynamics, and electronic motion rely on femtosecond laser sources capable of producing programmable arbitrarily shaped waveforms. To enter the time scale of natural dynamic processes in many systems, femtosecond pulse shaping techniques must be extended to the ultrashort pulse domain (<50 fs). Concurrently, reliable high-fidelity amplification of shaped waveforms is required in many applications. We demonstrate ultrabroad bandwidth pulse shaping of 13 fs pulses with Fourier-domain phase-only filtering using a liquid crystal array. We further demonstrate the amplification of shaped pulses in a multipass chirped pulse amplifier (CPA) system to produce millijoule-level optical waveforms with 30 fs resolution. Recently, a new approach to coherent control of physical systems was introduced, which, instead of relying on formidable theoretical calculations of complex system dynamics, makes use of an appropriate experimental feedback from the system itself to control its evolution. We apply this adaptive feedback approach for enhancement of ionization rates in a femtosecond plasma with the goal of minimization of phase distortions in the amplifier system. With the help of a learning algorithm and survival principles of nature, we teach our laser to control its own phase by using spectral blueshifting in a rapidly created plasma as a feedback to the algorithm. Control of lattice vibrations has long been sought as a means of studying phonon-related processes in solids. In addition, generation and control of large-amplitude optical phonon modes may open a path to femtosecond time- resolved studies of structural phase transitions and production of ultrashort shaped X-ray pulses. We perform pump-probe phase-resolved measurements and control of optical A1g mode in sapphire through shaped-pulse impulsive stimulated Raman scattering (ISRS). We chose this material as a candidate for possible nonlinear

  18. Finishing of additively manufactured titanium alloy by shape adaptive grinding (SAG)

    NASA Astrophysics Data System (ADS)

    Beaucamp, Anthony T.; Namba, Yoshiharu; Charlton, Phillip; Jain, Samyak; Graziano, Arthur A.

    2015-06-01

    In recent years, rapid prototyping of titanium alloy components for medical and aeronautics application has become viable thanks to advances in technologies such as electron beam melting (EBM) and selective laser sintering (SLS). However, for many applications the high surface roughness generated by additive manufacturing techniques demands a post-finishing operation to improve the surface quality prior to usage. In this paper, the novel shape adaptive grinding process has been applied to finishing titanium alloy (Ti6Al4V) additively manufactured by EBM and SLS. It is shown that the micro-structured surface layer resulting from the melting process can be removed, and the surface can then be smoothed down to less than 10 nm Ra (starting from 4-5 μm Ra) using only three different diamond grit sizes. This paper also demonstrates application of the technology to freeform shapes, and documents the dimensional accuracy of finished artifacts.

  19. Capacity achieving nonbinary LDPC coded non-uniform shaping modulation for adaptive optical communications.

    PubMed

    Lin, Changyu; Zou, Ding; Liu, Tao; Djordjevic, Ivan B

    2016-08-01

    A mutual information inspired nonbinary coded modulation design with non-uniform shaping is proposed. Instead of traditional power of two signal constellation sizes, we design 5-QAM, 7-QAM and 9-QAM constellations, which can be used in adaptive optical networks. The non-uniform shaping and LDPC code rate are jointly considered in the design, which results in a better performance scheme for the same SNR values. The matched nonbinary (NB) LDPC code is used for this scheme, which further improves the coding gain and the overall performance. We analyze both coding performance and system SNR performance. We show that the proposed NB LDPC-coded 9-QAM has more than 2dB gain in symbol SNR compared to traditional LDPC-coded star-8-QAM. On the other hand, the proposed NB LDPC-coded 5-QAM and 7-QAM have even better performance than LDPC-coded QPSK. PMID:27505775

  20. The Practical Impact of IRT Models and Parameters When Converting a Test to Adaptive Format.

    ERIC Educational Resources Information Center

    Bizot, Elizabeth B.; Goldman, Steven H.

    A study was conducted to evaluate the effects of choice of item response theory (IRT) model, parameter calibration group, starting ability estimate, and stopping criterion on the conversion of an 80-item vocabulary test to computer adaptive format. Three parameter calibration groups were tested: (1) a group of 1,000 high school seniors, (2) a…

  1. Light adaptation alters inner retinal inhibition to shape OFF retinal pathway signaling.

    PubMed

    Mazade, Reece E; Eggers, Erika D

    2016-06-01

    The retina adjusts its signaling gain over a wide range of light levels. A functional result of this is increased visual acuity at brighter luminance levels (light adaptation) due to shifts in the excitatory center-inhibitory surround receptive field parameters of ganglion cells that increases their sensitivity to smaller light stimuli. Recent work supports the idea that changes in ganglion cell spatial sensitivity with background luminance are due in part to inner retinal mechanisms, possibly including modulation of inhibition onto bipolar cells. To determine how the receptive fields of OFF cone bipolar cells may contribute to changes in ganglion cell resolution, the spatial extent and magnitude of inhibitory and excitatory inputs were measured from OFF bipolar cells under dark- and light-adapted conditions. There was no change in the OFF bipolar cell excitatory input with light adaptation; however, the spatial distributions of inhibitory inputs, including both glycinergic and GABAergic sources, became significantly narrower, smaller, and more transient. The magnitude and size of the OFF bipolar cell center-surround receptive fields as well as light-adapted changes in resting membrane potential were incorporated into a spatial model of OFF bipolar cell output to the downstream ganglion cells, which predicted an increase in signal output strength with light adaptation. We show a prominent role for inner retinal spatial signals in modulating the modeled strength of bipolar cell output to potentially play a role in ganglion cell visual sensitivity and acuity. PMID:26912599

  2. Synchronization of a class of chaotic systems with fully unknown parameters using adaptive sliding mode approach

    NASA Astrophysics Data System (ADS)

    Roopaei, M.; Zolghadri Jahromi, M.

    2008-12-01

    In this paper, an adaptive sliding mode control method for synchronization of a class of chaotic systems with fully unknown parameters is introduced. In this method, no knowledge of the bounds of parameters is required in advance and the parameters are updated through an adaptive control process. We use our proposed method to synchronize two chaotic gyros, which has been the subject of intense study during the recent years for its application in the navigational, aeronautical, and space engineering domains. The effectiveness of our method is demonstrated in simulation environment and the results are compared with some recent schemes proposed in the literature for the same task.

  3. Optimisation of Shape Parameters and Process Manufacturing for an Automotive Safety Part

    NASA Astrophysics Data System (ADS)

    Gildemyn, Eric; Dal Santo, Philippe; Potiron, Alain; Saïdane, Delphine

    2007-05-01

    In recent years, the weight and the cost of automotive vehicles have considerably increased due to the importance devoted to safety systems. It is therefore necessary to reduce the weight and the production cost of components by improving their shape and manufacturing process. This work deals with a numerical approach for optimizing the manufacturing process parameters of a safety belt anchor using a genetic algorithm (NSGA II). This type of component is typically manufactured in three stages: blanking, rounding of the edges by punching and finally, bending with a 90° angle. In this study, only the rounding and the bending will be treated. The numerical model is linked to the genetic algorithm in order to optimize the process parameters. This is implemented by using ABAQUSscript files developed in the Python programming language. The algorithm modifies the script files and restarts the FEM analysis automatically. Lemaitre's damage model is introduced in the material behaviour laws and implemented in the FEM analysis by using a FORTRAN subroutine. The influence of two process parameters (die radius and the rounding punch radius) and five shape parameters were investigated. The objective functions are (i) the material damage state at the end of the forming process, (ii) the stress field and (iii) the maximum Von Mises stress in the folded zone.

  4. Local stereo matching with adaptive shape support window based cost aggregation.

    PubMed

    Xu, Yafan; Zhao, Yan; Ji, Mengqi

    2014-10-10

    Cost aggregation is the most important step in a local stereo algorithm. In this work, a novel local stereo-matching algorithm with a cost-aggregation method based on adaptive shape support window (ASSW) is proposed. First, we compute the initial cost volume, which uses both absolute intensity difference and gradient similarity to measure dissimilarity. Second, we apply an ASSW-based cost-aggregation method to get the aggregated cost within the support window. There are two main parts: at first we construct a local support skeleton anchoring each pixel with four varying arm lengths decided on color similarity; as a result, the support window integral of multiple horizontal segments spanned by pixels in the neighboring vertical is established. Then we utilize extended implementation of guided filter to aggregate cost volume within the ASSW, which has better edge-preserving smoothing property than bilateral filter independent of the filtering kernel size. In this way, the number of bad pixels located in the incorrect depth regions can be effectively reduced through finding optimal support windows with an arbitrary shape and size adaptively. Finally, the initial disparity value of each pixel is selected using winner takes all optimization and post processing symmetrically, considering both the reference and the target image, is adopted. The experimental results demonstrate that the proposed algorithm achieves outstanding matching performance compared with other existing local algorithms on the Middlebury stereo benchmark, especially in depth discontinuities and piecewise smooth regions. PMID:25322396

  5. Radar meteors range distribution model. III. Ablation, shape-density and self-similarity parameters

    NASA Astrophysics Data System (ADS)

    Pecinová, D.; Pecina, P.

    2007-10-01

    The theoretical radar meteors Range Distribution of the overdense echoes developed by Pecinová and Pecina (2007 a) is applied here to observed range distributions of meteors belonging to the Quadrantid, Perseid, Leonid, Geminid, γ Draconid (Giacobinid), ζ Perseid and β Taurid streams to study the variability of the shape-density, ablation, and self-similarity parameters of meteoroids of these streams. We have found in accordance with results of photographical observations that ablation parameter σ is higher for members of showers of clearly cometary origin, and is lower for Geminid and daytime shower meteoroids. Levin's self-similarity parameter μ was found to be much greater than the classical value 2/3 for all investigated streams with the exception of Geminids, for which the value found is almost classical, i.e. 0.66 ± 0.01. The method of getting μ by means of fitting the light curve of faint TV meteors is also suggested.

  6. Extraction of modal parameters with the aid of predicted analytical mode shapes

    SciTech Connect

    Mayes, R.L.; Carne, T.G.

    1996-02-01

    The extraction of the modal parameters for closely spaced modes in the frequency domain is a common problem. However, it is made more difficult if the damping for the closely spaced modes is high. Data from a structure with more than three percent viscous damping is presented which exhibits this phenomenon. Traditional experimental techniques failed to identify all the modal parameters of three closely spaced modes. Mode shapes from an analytical model are manipulated to produce a modal filter which is used to calculate enhanced frequency response functions from which the modal parameters can be more readily identified. Discussion of the advantages and disadvantages of this technique as compared with traditional frequency response function enhancement techniques will be presented.

  7. Generalized Extreme Value's shape parameter and its nature for extreme precipitation using long time series and Bayesian approach

    NASA Astrophysics Data System (ADS)

    Ragulina, Galina; Reitan, Trond

    2016-04-01

    Assessing the probability of extreme precipitation events is of great importance in civil planning. This requires understanding of how return values change with different return periods, which is essentially described by the Generalized Extreme Value distribution's shape parameter. Some works in the field have suggested a constant shape parameter, while our analysis indicates a non-universal value. We first re-analyse an older precipitation dataset (169 stations) extended by Norwegian data (71 stations). We show that while each set seems to have a constant shape parameter, it differs between the two datasets, indicating regional differences. For a more comprehensive analysis of spatial effects, we examine a global dataset (1495 stations). We provide shape parameter maps for two models. We find clear evidence for the shape parameter being dependent on elevation while the effect of latitude remains uncertain. Our results confirm an explanation in terms of dominating precipitation systems based on a proxy derived from the Köppen-Geiger climate classification.

  8. Model Reference Adaptive H∞ Control for a Class of Mixed Parameter Systems by Finite Dimensional Controllers

    NASA Astrophysics Data System (ADS)

    Miyasato, Yoshihiko

    The problem of constructing model reference adaptive H∞ control for a class of mixed parameter systems is considered in this manuscript. Mixed parameter systems are complex processes composed of distributed parameter systems (infinite dimensional systems) and lumped parameter systems (finite dimensional systems). Owing to infinite dimensional modes of distributed parameter systems, control of those complex systems via finite dimensional compensators, is a difficult but important problem from both theoretical and practical viewpoints. A stabilizing control signal is added to regulate the effect of infinite dimensional modes, and it is derived as a solution of certain H∞ control problem where the effect of infinite dimensional modes are considered as external disturbances to the process.

  9. Adaptive digital fringe projection technique for high dynamic range three-dimensional shape measurement.

    PubMed

    Lin, Hui; Gao, Jian; Mei, Qing; He, Yunbo; Liu, Junxiu; Wang, Xingjin

    2016-04-01

    It is a challenge for any optical method to measure objects with a large range of reflectivity variation across the surface. Image saturation results in incorrect intensities in captured fringe pattern images, leading to phase and measurement errors. This paper presents a new adaptive digital fringe projection technique which avoids image saturation and has a high signal to noise ratio (SNR) in the three-dimensional (3-D) shape measurement of objects that has a large range of reflectivity variation across the surface. Compared to previous high dynamic range 3-D scan methods using many exposures and fringe pattern projections, which consumes a lot of time, the proposed technique uses only two preliminary steps of fringe pattern projection and image capture to generate the adapted fringe patterns, by adaptively adjusting the pixel-wise intensity of the projected fringe patterns based on the saturated pixels in the captured images of the surface being measured. For the bright regions due to high surface reflectivity and high illumination by the ambient light and surfaces interreflections, the projected intensity is reduced just to be low enough to avoid image saturation. Simultaneously, the maximum intensity of 255 is used for those dark regions with low surface reflectivity to maintain high SNR. Our experiments demonstrate that the proposed technique can achieve higher 3-D measurement accuracy across a surface with a large range of reflectivity variation. PMID:27137056

  10. Identification of rolling resistance as a shape parameter in sheared granular media.

    PubMed

    Estrada, Nicolas; Azéma, Emilien; Radjai, Farhang; Taboada, Alfredo

    2011-07-01

    Using contact dynamics simulations, we compare the effect of rolling resistance at the contacts in granular systems composed of disks with the effect of angularity in granular systems composed of regular polygonal particles. In simple shear conditions, we consider four aspects of the mechanical behavior of these systems in the steady state: shear strength, solid fraction, force and fabric anisotropies, and probability distribution of contact forces. Our main finding is that, based on the energy dissipation associated with relative rotation between two particles in contact, the effect of rolling resistance can explicitly be identified with that of the number of sides in a regular polygonal particle. This finding supports the use of rolling resistance as a shape parameter accounting for particle angularity and shows unambiguously that one of the main influencing factors behind the mechanical behavior of granular systems composed of noncircular particles is the partial hindrance of rotations as a result of angular particle shape. PMID:21867163

  11. SDSS-II: Determination of shape and color parameter coefficients for SALT-II fit model

    SciTech Connect

    Dojcsak, L.; Marriner, J.; /Fermilab

    2010-08-01

    In this study we look at the SALT-II model of Type IA supernova analysis, which determines the distance moduli based on the known absolute standard candle magnitude of the Type IA supernovae. We take a look at the determination of the shape and color parameter coefficients, {alpha} and {beta} respectively, in the SALT-II model with the intrinsic error that is determined from the data. Using the SNANA software package provided for the analysis of Type IA supernovae, we use a standard Monte Carlo simulation to generate data with known parameters to use as a tool for analyzing the trends in the model based on certain assumptions about the intrinsic error. In order to find the best standard candle model, we try to minimize the residuals on the Hubble diagram by calculating the correct shape and color parameter coefficients. We can estimate the magnitude of the intrinsic errors required to obtain results with {chi}{sup 2}/degree of freedom = 1. We can use the simulation to estimate the amount of color smearing as indicated by the data for our model. We find that the color smearing model works as a general estimate of the color smearing, and that we are able to use the RMS distribution in the variables as one method of estimating the correct intrinsic errors needed by the data to obtain the correct results for {alpha} and {beta}. We then apply the resultant intrinsic error matrix to the real data and show our results.

  12. Shape parameters and distribution of macroborings: St. Croix, US Virgin Islands

    SciTech Connect

    Jacobs, E.B.

    1983-03-01

    Many marine invertebrates that inhabit coral reefs excavate the coral substrate in order to create protective domiciles. In turn, the organisms comprising the coral-reef community display a pronounced biotic zonation that can be closely correlated to bathymetry. This study considers the distribution of these endolithic organisms covering a variety of reef habitats. Vast differences in the major environmental parameters have a profound effect upon the distribution patterns of macroboring organisms and govern the boring morphologies. Of these parameters, hydraulic energy has the strongest influences on the morphotypes and distributions of the macroborings. An equivalent macroboring assemblage dominated by sponges and bivalves prevails in both the shallow back-reef zone and the deep fore-reef zone, both of which are low-energy settings. Boring assemblages in more turbulent zones within the reef consist of polychaete and sipunculid worms, sea urchins, and barnacles, with sponges and bivalves less dominant and less abundant. Other environmental factors which may be important locally include: nutrient availability, photic energy, sediment size and sedimentation rate, competition for substrate, and predation pressure upon the live coral tissue. Shape parameters for different boring types are provided as a means of identification and as an indication of the environmental control upon boring shape. An understanding of the variability of boring types with respect to the ambient environment within modern reefs facilitates the use of borings as paleoenvironmental indicators within Cenozoic carbonate systems.

  13. A moving-window parameter adaptive control system for the F8-DFBW aircraft

    NASA Technical Reports Server (NTRS)

    Montgomery, R. C.; Dunn, H. J.

    1976-01-01

    This paper describes the moving-window parameter adaptive control system developed for the NASA F8-DFBW aircraft. The control system employs a parameter identification process that, iteratively, adjusts parameters of a model of the aircraft motions in a batch processing manner so that responses generated from the model fit the outputs of sensors stored in a finite record referred to as the moving window. Tests are made on the validity of the parameter estimates before using the parameters in an on-line design process. The on-line design process is an algebraic mapping of the parameters of the model into primary control system feedback and feedforward gains. The mapping was selected to satisfy specific flying quality characteristics over the range of parameter variations expected. Results are presented from simulation studies on the identification algorithm, tests for parameter validity, and the on-line design process.

  14. A self-adaptive genetic algorithm to estimate JA model parameters considering minor loops

    NASA Astrophysics Data System (ADS)

    Lu, Hai-liang; Wen, Xi-shan; Lan, Lei; An, Yun-zhu; Li, Xiao-ping

    2015-01-01

    A self-adaptive genetic algorithm for estimating Jiles-Atherton (JA) magnetic hysteresis model parameters is presented. The fitness function is established based on the distances between equidistant key points of normalized hysteresis loops. Linearity function and logarithm function are both adopted to code the five parameters of JA model. Roulette wheel selection is used and the selection pressure is adjusted adaptively by deducting a proportional which depends on current generation common value. The Crossover operator is established by combining arithmetic crossover and multipoint crossover. Nonuniform mutation is improved by adjusting the mutation ratio adaptively. The algorithm is used to estimate the parameters of one kind of silicon-steel sheet's hysteresis loops, and the results are in good agreement with published data.

  15. Systems and Methods for Parameter Dependent Riccati Equation Approaches to Adaptive Control

    NASA Technical Reports Server (NTRS)

    Kim, Kilsoo (Inventor); Yucelen, Tansel (Inventor); Calise, Anthony J. (Inventor)

    2015-01-01

    Systems and methods for adaptive control are disclosed. The systems and methods can control uncertain dynamic systems. The control system can comprise a controller that employs a parameter dependent Riccati equation. The controller can produce a response that causes the state of the system to remain bounded. The control system can control both minimum phase and non-minimum phase systems. The control system can augment an existing, non-adaptive control design without modifying the gains employed in that design. The control system can also avoid the use of high gains in both the observer design and the adaptive control law.

  16. Effects of laser parameters on the geometrical characteristics of peg-shaped bionic coupling unit

    NASA Astrophysics Data System (ADS)

    Zhang, Baoyu; Zhang, Zhihui; Liang, Yunhong; Yan, Qiongqiong; Ren, Luquan

    2014-12-01

    Peg-shaped bionic coupling unit (PBCU) processed by pulse laser is effective in anti-adhesion, anti-drag, anti-wear and anti-fatigue application. To obtain desired structural and morphological characteristics of the PBCU for industrial manufacturing, selection of proper processing parameters gradually becomes a growing important problem. Traditionally, the procedure of parameter selecting is often cost-plus and time-consuming. In this work, a statistical analysis of fabricating PBCU on the surface of medium carbon steel was conducted. The laser processing parameters utilized in the experiment and analysis are peak power 4-8 kW, pulse duration 6-16 ms and defocusing amount 6-10 mm. A series of mathematical models regarding the relationship between geometrical characteristics of PBCU and laser processing parameters were developed and checked. The results indicate that the developed models can be adequately used to control the structural and morphological characteristics of PBCU within the scope of analysis. Based on the models, the formation mechanism of the structural and morphological characteristics under different laser parameters were analyzed and discussed.

  17. Exponential parameter and tracking error convergence guarantees for adaptive controllers without persistency of excitation

    NASA Astrophysics Data System (ADS)

    Chowdhary, Girish; Mühlegg, Maximilian; Johnson, Eric

    2014-08-01

    In model reference adaptive control (MRAC) the modelling uncertainty is often assumed to be parameterised with time-invariant unknown ideal parameters. The convergence of parameters of the adaptive element to these ideal parameters is beneficial, as it guarantees exponential stability, and makes an online learned model of the system available. Most MRAC methods, however, require persistent excitation of the states to guarantee that the adaptive parameters converge to the ideal values. Enforcing PE may be resource intensive and often infeasible in practice. This paper presents theoretical analysis and illustrative examples of an adaptive control method that leverages the increasing ability to record and process data online by using specifically selected and online recorded data concurrently with instantaneous data for adaptation. It is shown that when the system uncertainty can be modelled as a combination of known nonlinear bases, simultaneous exponential tracking and parameter error convergence can be guaranteed if the system states are exciting over finite intervals such that rich data can be recorded online; PE is not required. Furthermore, the rate of convergence is directly proportional to the minimum singular value of the matrix containing online recorded data. Consequently, an online algorithm to record and forget data is presented and its effects on the resulting switched closed-loop dynamics are analysed. It is also shown that when radial basis function neural networks (NNs) are used as adaptive elements, the method guarantees exponential convergence of the NN parameters to a compact neighbourhood of their ideal values without requiring PE. Flight test results on a fixed-wing unmanned aerial vehicle demonstrate the effectiveness of the method.

  18. Lower bound on reliability for Weibull distribution when shape parameter is not estimated accurately

    NASA Technical Reports Server (NTRS)

    Huang, Zhaofeng; Porter, Albert A.

    1991-01-01

    The mathematical relationships between the shape parameter Beta and estimates of reliability and a life limit lower bound for the two parameter Weibull distribution are investigated. It is shown that under rather general conditions, both the reliability lower bound and the allowable life limit lower bound (often called a tolerance limit) have unique global minimums over a range of Beta. Hence lower bound solutions can be obtained without assuming or estimating Beta. The existence and uniqueness of these lower bounds are proven. Some real data examples are given to show how these lower bounds can be easily established and to demonstrate their practicality. The method developed here has proven to be extremely useful when using the Weibull distribution in analysis of no-failure or few-failures data. The results are applicable not only in the aerospace industry but anywhere that system reliabilities are high.

  19. Lower bound on reliability for Weibull distribution when shape parameter is not estimated accurately

    NASA Technical Reports Server (NTRS)

    Huang, Zhaofeng; Porter, Albert A.

    1990-01-01

    The mathematical relationships between the shape parameter Beta and estimates of reliability and a life limit lower bound for the two parameter Weibull distribution are investigated. It is shown that under rather general conditions, both the reliability lower bound and the allowable life limit lower bound (often called a tolerance limit) have unique global minimums over a range of Beta. Hence lower bound solutions can be obtained without assuming or estimating Beta. The existence and uniqueness of these lower bounds are proven. Some real data examples are given to show how these lower bounds can be easily established and to demonstrate their practicality. The method developed here has proven to be extremely useful when using the Weibull distribution in analysis of no-failure or few-failures data. The results are applicable not only in the aerospace industry but anywhere that system reliabilities are high.

  20. Adaptive Control Parameters for Dispersal of Multi-Agent Mobile Ad Hoc Network (MANET) Swarms

    SciTech Connect

    Kurt Derr; Milos Manic

    2013-11-01

    A mobile ad hoc network is a collection of independent nodes that communicate wirelessly with one another. This paper investigates nodes that are swarm robots with communications and sensing capabilities. Each robot in the swarm may operate in a distributed and decentralized manner to achieve some goal. This paper presents a novel approach to dynamically adapting control parameters to achieve mesh configuration stability. The presented approach to robot interaction is based on spring force laws (attraction and repulsion laws) to create near-optimal mesh like configurations. In prior work, we presented the extended virtual spring mesh (EVSM) algorithm for the dispersion of robot swarms. This paper extends the EVSM framework by providing the first known study on the effects of adaptive versus static control parameters on robot swarm stability. The EVSM algorithm provides the following novelties: 1) improved performance with adaptive control parameters and 2) accelerated convergence with high formation effectiveness. Simulation results show that 120 robots reach convergence using adaptive control parameters more than twice as fast as with static control parameters in a multiple obstacle environment.

  1. A moving window parameter adaptive control system for the F8-DFBW aircraft

    NASA Technical Reports Server (NTRS)

    Dunn, H. J.; Montgomery, R. C.

    1977-01-01

    This paper describes the moving window parameter adaptive control system developed for the NASA F8-DFBW aircraft. The control system employs a parameter identification process that, iteratively, adjusts parameters of a model of the aircraft motions in a batch-processing manner so that responses generated from the model fit the outputs of sensors stored in a finite record referred to as the moving window. Tests are made on the validity of the parameter estimates before using the parameters in an on-line design process. The on-line design process is an algebraic mapping of the parameters of the model into primary control system feedback and feedforward gains. The mapping was selected to satisfy specific flying quality characteristics over the range of parameter variations expected. Results are presented from simulation studies on the identification algorithm made during the development of the system.

  2. Selection of shape parameters that differentiate sand grains, based on the automatic analysis of two-dimensional images

    NASA Astrophysics Data System (ADS)

    Sochan, Agata; Zieliński, Paweł; Bieganowski, Andrzej

    2015-08-01

    A grain shape analysis of sandy deposits has implications for determining the processes that affect grain shape. So far, most methods of carrying out a grain shape analysis are based on the subjective estimation of the researcher. The purpose of this study is to indicate the shape parameter/parameters that best differentiate sand grains, and to compare the results with those that have been obtained by the Krumbein method. We determined the shape parameters of sand grains (size range from 0.71 mm to 1 mm) using photos of two-dimensional images of particle projections onto a plane. The photos were taken under an optical microscope and were then subjected to an image analysis. We selected six shape parameters that best differentiate the studied sand grains, based on the criteria of: i) the monotonicity of parameter value, which changed depending on the categorization of the grains to the successive Krumbein roundness classes, and ii) the statistical significance of differences between the optical parameter values in the individual Krumbein classes. We selected three circularity parameters (θ1, θ4 and θ5) and three surface structure parameters (κ3, κ4 and κ6). None of these shape parameters allowed the direct categorization of a particle into a particular Krumbein roundness class. Nevertheless, despite the fact that an unambiguous characterization of deposits is not possible, this method can be helpful in identifying the origin of deposits. Moreover, it is possible to develop more advanced methods (e.g., based on artificial intelligence tools), which would allow an unambiguous categorization based on the determined shape parameters.

  3. Inversion for Refractivity Parameters Using a Dynamic Adaptive Cuckoo Search with Crossover Operator Algorithm

    PubMed Central

    Zhang, Zhihua; Sheng, Zheng; Shi, Hanqing; Fan, Zhiqiang

    2016-01-01

    Using the RFC technique to estimate refractivity parameters is a complex nonlinear optimization problem. In this paper, an improved cuckoo search (CS) algorithm is proposed to deal with this problem. To enhance the performance of the CS algorithm, a parameter dynamic adaptive operation and crossover operation were integrated into the standard CS (DACS-CO). Rechenberg's 1/5 criteria combined with learning factor were used to control the parameter dynamic adaptive adjusting process. The crossover operation of genetic algorithm was utilized to guarantee the population diversity. The new hybrid algorithm has better local search ability and contributes to superior performance. To verify the ability of the DACS-CO algorithm to estimate atmospheric refractivity parameters, the simulation data and real radar clutter data are both implemented. The numerical experiments demonstrate that the DACS-CO algorithm can provide an effective method for near-real-time estimation of the atmospheric refractivity profile from radar clutter. PMID:27212938

  4. Inversion for Refractivity Parameters Using a Dynamic Adaptive Cuckoo Search with Crossover Operator Algorithm.

    PubMed

    Zhang, Zhihua; Sheng, Zheng; Shi, Hanqing; Fan, Zhiqiang

    2016-01-01

    Using the RFC technique to estimate refractivity parameters is a complex nonlinear optimization problem. In this paper, an improved cuckoo search (CS) algorithm is proposed to deal with this problem. To enhance the performance of the CS algorithm, a parameter dynamic adaptive operation and crossover operation were integrated into the standard CS (DACS-CO). Rechenberg's 1/5 criteria combined with learning factor were used to control the parameter dynamic adaptive adjusting process. The crossover operation of genetic algorithm was utilized to guarantee the population diversity. The new hybrid algorithm has better local search ability and contributes to superior performance. To verify the ability of the DACS-CO algorithm to estimate atmospheric refractivity parameters, the simulation data and real radar clutter data are both implemented. The numerical experiments demonstrate that the DACS-CO algorithm can provide an effective method for near-real-time estimation of the atmospheric refractivity profile from radar clutter. PMID:27212938

  5. Model Reference Adaptive H∞ Control for Distributed Parameter Systems of Hyperbolic Type by Finite Dimensional Controllers

    NASA Astrophysics Data System (ADS)

    Miyasato, Yoshihiko

    The problem of constructing model reference adaptive H∞ control for distributed parameters systems of hyperbolic type is considered in this paper. Distributed parameters systems are infinite dimensional processes, but the proposed control scheme is constructed from finite dimensional controllers. The stabilizing control signal is added to regulate the effect of spill-over terms, and it is derived as a solution of certain H∞ control problem where spill-overs are considered as external disturbances to the process.

  6. Controlled Aeroelastic Response and Airfoil Shaping Using Adaptive Materials and Integrated Systems

    NASA Technical Reports Server (NTRS)

    Pinkerton, Jennifer L.; McGowan, Anna-Maria R.; Moses, Robert W.; Scott, Robert C.; Heeg, Jennifer

    1996-01-01

    This paper presents an overview of several activities of the Aeroelasticity Branch at the NASA Langley Research Center in the area of applying adaptive materials and integrated systems for controlling both aircraft aeroelastic response and airfoil shape. The experimental results of four programs are discussed: the Piezoelectric Aeroelastic Response Tailoring Investigation (PARTI); the Adaptive Neural Control of Aeroelastic Response (ANCAR) program; the Actively Controlled Response of Buffet Affected Tails (ACROBAT) program; and the Airfoil THUNDER Testing to Ascertain Characteristics (ATTACH) project. The PARTI program demonstrated active flutter control and significant rcductions in aeroelastic response at dynamic pressures below flutter using piezoelectric actuators. The ANCAR program seeks to demonstrate the effectiveness of using neural networks to schedule flutter suppression control laws. Th,e ACROBAT program studied the effectiveness of a number of candidate actuators, including a rudder and piezoelectric actuators, to alleviate vertical tail buffeting. In the ATTACH project, the feasibility of using Thin-Layer Composite-Uimorph Piezoelectric Driver and Sensor (THUNDER) wafers to control airfoil aerodynamic characteristics was investigated. Plans for future applications are also discussed.

  7. Controlled aeroelastic response and airfoil shaping using adaptive materials and integrated systems

    NASA Astrophysics Data System (ADS)

    Pinkerton, Jennifer L.; McGowan, Anna-Maria R.; Moses, Robert W.; Scott, Robert C.; Heeg, Jennifer

    1996-05-01

    This paper presents an overview of several activities of the Aeroelasticity Branch at the NASA Langley Research Center in the area of applying adaptive materials and integrated systems for controlling both aircraft aeroelastic response and airfoil shape. The experimental results of four programs are discussed: the Piezoelectric Aeroelastic Response Tailoring Investigation (PARTI); the adaptive neural control of aeroelastic response (ANCAR) program; the actively controlled response of buffet affected tails (ACROBAT) program; and the Airfoil THUNDER Testing to ascertain charcteristics (ATTACH) project. The PARTI program demonstrated active flutter control and significant reductions in aeroelastic response at dynamic pressures below flutter using piezoelectric actuators. The ANCAR program seeks to demonstrate the effectiveness of using neural networks to schedule flutter suppression control laws. The ACROBAT program studied the effectiveness of a number of candidate actuators, including a rudder and piezoelectric actuators, to alleviate vertical tail buffeting. In the ATTACH project, the feasibility of using thin-layer composite-unimorph piezoelectric driver and sensor (THUNDER) wafers to control airfoil aerodynamic characteristics was investigated. Plans for future applications are also discussed.

  8. Adaptive niche radii and niche shapes approaches for niching with the CMA-ES.

    PubMed

    Shir, Ofer M; Emmerich, Michael; Bäck, Thomas

    2010-01-01

    While the motivation and usefulness of niching methods is beyond doubt, the relaxation of assumptions and limitations concerning the hypothetical search landscape is much needed if niching is to be valid in a broader range of applications. Upon the introduction of radii-based niching methods with derandomized evolution strategies (ES), the purpose of this study is to address the so-called niche radius problem. A new concept of an adaptive individual niche radius is applied to niching with the covariance matrix adaptation evolution strategy (CMA-ES). Two approaches are considered. The first approach couples the radius to the step size mechanism, while the second approach employs the Mahalanobis distance metric with the covariance matrix mechanism for the distance calculation, for obtaining niches with more complex geometrical shapes. The proposed approaches are described in detail, and then tested on high-dimensional artificial landscapes at several levels of difficulty. They are shown to be robust and to achieve satisfying results. PMID:20064027

  9. Morphology analysis of EKG R waves using wavelets with adaptive parameters derived from fuzzy logic

    NASA Astrophysics Data System (ADS)

    Caldwell, Max A.; Barrington, William W.; Miles, Richard R.

    1996-03-01

    Understanding of the EKG components P, QRS (R wave), and T is essential in recognizing cardiac disorders and arrhythmias. An estimation method is presented that models the R wave component of the EKG by adaptively computing wavelet parameters using fuzzy logic. The parameters are adaptively adjusted to minimize the difference between the original EKG waveform and the wavelet. The R wave estimate is derived from minimizing the combination of mean squared error (MSE), amplitude difference, spread difference, and shift difference. We show that the MSE in both non-noise and additive noise environment is less using an adaptive wavelet than a static wavelet. Research to date has focused on the R wave component of the EKG signal. Extensions of this method to model P and T waves are discussed.

  10. Parameter estimation with an iterative version of the adaptive Gaussian mixture filter

    NASA Astrophysics Data System (ADS)

    Stordal, A.; Lorentzen, R.

    2012-04-01

    The adaptive Gaussian mixture filter (AGM) was introduced in Stordal et. al. (ECMOR 2010) as a robust filter technique for large scale applications and an alternative to the well known ensemble Kalman filter (EnKF). It consists of two analysis steps, one linear update and one weighting/resampling step. The bias of AGM is determined by two parameters, one adaptive weight parameter (forcing the weights to be more uniform to avoid filter collapse) and one pre-determined bandwidth parameter which decides the size of the linear update. It has been shown that if the adaptive parameter approaches one and the bandwidth parameter decrease with increasing sample size, the filter can achieve asymptotic optimality. For large scale applications with a limited sample size the filter solution may be far from optimal as the adaptive parameter gets close to zero depending on how well the samples from the prior distribution match the data. The bandwidth parameter must often be selected significantly different from zero in order to make large enough linear updates to match the data, at the expense of bias in the estimates. In the iterative AGM we take advantage of the fact that the history matching problem is usually estimation of parameters and initial conditions. If the prior distribution of initial conditions and parameters is close to the posterior distribution, it is possible to match the historical data with a small bandwidth parameter and an adaptive weight parameter that gets close to one. Hence the bias of the filter solution is small. In order to obtain this scenario we iteratively run the AGM throughout the data history with a very small bandwidth to create a new prior distribution from the updated samples after each iteration. After a few iterations, nearly all samples from the previous iteration match the data and the above scenario is achieved. A simple toy problem shows that it is possible to reconstruct the true posterior distribution using the iterative version of

  11. Computerized Adaptive Testing: A Comparison of the Nominal Response Model and the Three Parameter Logistic Model.

    ERIC Educational Resources Information Center

    DeAyala, R. J.; Koch, William R.

    A nominal response model-based computerized adaptive testing procedure (nominal CAT) was implemented using simulated data. Ability estimates from the nominal CAT were compared to those from a CAT based upon the three-parameter logistic model (3PL CAT). Furthermore, estimates from both CAT procedures were compared with the known true abilities used…

  12. Influence of Fallible Item Parameters on Test Information During Adaptive Testing.

    ERIC Educational Resources Information Center

    Wetzel, C. Douglas; McBride, James R.

    Computer simulation was used to assess the effects of item parameter estimation errors on different item selection strategies used in adaptive and conventional testing. To determine whether these effects reduced the advantages of certain optimal item selection strategies, simulations were repeated in the presence and absence of item parameter…

  13. New Directions in Asymptotically Stable Finite-dimensional Adaptive Control of Linear Distributed Parameter Systems

    NASA Technical Reports Server (NTRS)

    Balas, M. J.

    1985-01-01

    Distributed Parameter Systems (DPS), such as systems described by partial differential equations, require infinite-dimensional state space descriptions to correctly model their dynamical behavior. However, any adaptive control algorithm must be finite-dimensional in order to be implemented via on-line digital computers. Finite-dimensional adaptive control of linear DPS requires stability analysis of nonlinear, time-varying, infinite-dimensional systems. The structure of nonadaptive finite-dimensional control of linear DPS is summarized as it relates to the existence of limiting systems for adaptive control. Two candidate schemes for finite-dimensional adaptive control of DPS are described and critical issues in infinite-dimensional stability analysis are discussed, in particular, the invariance principle, center manifold theory, and relationships between input-output and internal stability.

  14. Parameter estimation for chaotic systems using a hybrid adaptive cuckoo search with simulated annealing algorithm.

    PubMed

    Sheng, Zheng; Wang, Jun; Zhou, Shudao; Zhou, Bihua

    2014-03-01

    This paper introduces a novel hybrid optimization algorithm to establish the parameters of chaotic systems. In order to deal with the weaknesses of the traditional cuckoo search algorithm, the proposed adaptive cuckoo search with simulated annealing algorithm is presented, which incorporates the adaptive parameters adjusting operation and the simulated annealing operation in the cuckoo search algorithm. Normally, the parameters of the cuckoo search algorithm are kept constant that may result in decreasing the efficiency of the algorithm. For the purpose of balancing and enhancing the accuracy and convergence rate of the cuckoo search algorithm, the adaptive operation is presented to tune the parameters properly. Besides, the local search capability of cuckoo search algorithm is relatively weak that may decrease the quality of optimization. So the simulated annealing operation is merged into the cuckoo search algorithm to enhance the local search ability and improve the accuracy and reliability of the results. The functionality of the proposed hybrid algorithm is investigated through the Lorenz chaotic system under the noiseless and noise condition, respectively. The numerical results demonstrate that the method can estimate parameters efficiently and accurately in the noiseless and noise condition. Finally, the results are compared with the traditional cuckoo search algorithm, genetic algorithm, and particle swarm optimization algorithm. Simulation results demonstrate the effectiveness and superior performance of the proposed algorithm. PMID:24697395

  15. Parameter estimation for chaotic systems using a hybrid adaptive cuckoo search with simulated annealing algorithm

    SciTech Connect

    Sheng, Zheng; Wang, Jun; Zhou, Bihua; Zhou, Shudao

    2014-03-15

    This paper introduces a novel hybrid optimization algorithm to establish the parameters of chaotic systems. In order to deal with the weaknesses of the traditional cuckoo search algorithm, the proposed adaptive cuckoo search with simulated annealing algorithm is presented, which incorporates the adaptive parameters adjusting operation and the simulated annealing operation in the cuckoo search algorithm. Normally, the parameters of the cuckoo search algorithm are kept constant that may result in decreasing the efficiency of the algorithm. For the purpose of balancing and enhancing the accuracy and convergence rate of the cuckoo search algorithm, the adaptive operation is presented to tune the parameters properly. Besides, the local search capability of cuckoo search algorithm is relatively weak that may decrease the quality of optimization. So the simulated annealing operation is merged into the cuckoo search algorithm to enhance the local search ability and improve the accuracy and reliability of the results. The functionality of the proposed hybrid algorithm is investigated through the Lorenz chaotic system under the noiseless and noise condition, respectively. The numerical results demonstrate that the method can estimate parameters efficiently and accurately in the noiseless and noise condition. Finally, the results are compared with the traditional cuckoo search algorithm, genetic algorithm, and particle swarm optimization algorithm. Simulation results demonstrate the effectiveness and superior performance of the proposed algorithm.

  16. Parameter estimation for chaotic systems using a hybrid adaptive cuckoo search with simulated annealing algorithm

    NASA Astrophysics Data System (ADS)

    Sheng, Zheng; Wang, Jun; Zhou, Shudao; Zhou, Bihua

    2014-03-01

    This paper introduces a novel hybrid optimization algorithm to establish the parameters of chaotic systems. In order to deal with the weaknesses of the traditional cuckoo search algorithm, the proposed adaptive cuckoo search with simulated annealing algorithm is presented, which incorporates the adaptive parameters adjusting operation and the simulated annealing operation in the cuckoo search algorithm. Normally, the parameters of the cuckoo search algorithm are kept constant that may result in decreasing the efficiency of the algorithm. For the purpose of balancing and enhancing the accuracy and convergence rate of the cuckoo search algorithm, the adaptive operation is presented to tune the parameters properly. Besides, the local search capability of cuckoo search algorithm is relatively weak that may decrease the quality of optimization. So the simulated annealing operation is merged into the cuckoo search algorithm to enhance the local search ability and improve the accuracy and reliability of the results. The functionality of the proposed hybrid algorithm is investigated through the Lorenz chaotic system under the noiseless and noise condition, respectively. The numerical results demonstrate that the method can estimate parameters efficiently and accurately in the noiseless and noise condition. Finally, the results are compared with the traditional cuckoo search algorithm, genetic algorithm, and particle swarm optimization algorithm. Simulation results demonstrate the effectiveness and superior performance of the proposed algorithm.

  17. Adaptability and Prediction of Anticipatory Muscular Activity Parameters to Different Movements in the Sitting Position.

    PubMed

    Chikh, Soufien; Watelain, Eric; Faupin, Arnaud; Pinti, Antonio; Jarraya, Mohamed; Garnier, Cyril

    2016-08-01

    Voluntary movement often causes postural perturbation that requires an anticipatory postural adjustment to minimize perturbation and increase the efficiency and coordination during execution. This systematic review focuses specifically on the relationship between the parameters of anticipatory muscular activities and movement finality in sitting position among adults, to study the adaptability and predictability of anticipatory muscular activities parameters to different movements and conditions in sitting position in adults. A systematic literature search was performed using PubMed, Science Direct, Web of Science, Springer-Link, Engineering Village, and EbscoHost. Inclusion and exclusion criteria were applied to retain the most rigorous and specific studies, yielding 76 articles, Seventeen articles were excluded at first reading, and after the application of inclusion and exclusion criteria, 23 were retained. In a sitting position, central nervous system activity precedes movement by diverse anticipatory muscular activities and shows the ability to adapt anticipatory muscular activity parameters to the movement direction, postural stability, or charge weight. In addition, these parameters could be adapted to the speed of execution, as found for the standing position. Parameters of anticipatory muscular activities (duration, order, and amplitude of muscle contractions constituting the anticipatory muscular activity) could be used as a predictive indicator of forthcoming movement. In addition, this systematic review may improve methodology in empirical studies and assistive technology for people with disabilities. PMID:27440765

  18. The eye lens: age-related trends and individual variations in refractive index and shape parameters.

    PubMed

    Pierscionek, Barbara; Bahrami, Mehdi; Hoshino, Masato; Uesugi, Kentaro; Regini, Justyn; Yagi, Naoto

    2015-10-13

    The eye lens grows throughout life by cell accrual on its surface and can change shape to adjust the focussing power of the eye. Varying concentrations of proteins in successive cell layers create a refractive index gradient. The continued growth of the lens and age-related changes in proteins render it less able to alter shape with loss of capacity by the end of the sixth decade of life. Growth and protein ageing alter the refractive index but as accurate measurement of this parameter is difficult, the nature of such alterations remains uncertain. The most accurate method to date for measuring refractive index in intact lenses has been developed at the SPring-8 synchrotron. The technique, based on Talbot interferometry, has an X-ray source and was used to measure refractive index in sixty-six human lenses, aged from 16 to 91 years. Height and width were measured for forty-five lenses. Refractive index contours show decentration in some older lenses but individual variations mask age-related trends. Refractive index profiles along the optic axis have relatively flat central sections with distinct micro-fluctuations and a steep gradient in the cortex but do not exhibit an age-related trend. The refractive index profiles in the equatorial aspect show statistical significance with age, particularly for lenses below the age of sixty that had capacity to alter shape in vivo. The maximum refractive index in the lens centre decreases slightly with age with considerable scatter in the data and there are age-related variations in sagittal thickness and equatorial height. PMID:26416418

  19. The eye lens: age-related trends and individual variations in refractive index and shape parameters

    PubMed Central

    Pierscionek, Barbara; Bahrami, Mehdi; Hoshino, Masato; Uesugi, Kentaro; Regini, Justyn; Yagi, Naoto

    2015-01-01

    The eye lens grows throughout life by cell accrual on its surface and can change shape to adjust the focussing power of the eye. Varying concentrations of proteins in successive cell layers create a refractive index gradient. The continued growth of the lens and age-related changes in proteins render it less able to alter shape with loss of capacity by the end of the sixth decade of life. Growth and protein ageing alter the refractive index but as accurate measurement of this parameter is difficult, the nature of such alterations remains uncertain. The most accurate method to date for measuring refractive index in intact lenses has been developed at the SPring-8 synchrotron. The technique, based on Talbot interferometry, has an X-ray source and was used to measure refractive index in sixty-six human lenses, aged from 16 to 91 years. Height and width were measured for forty-five lenses. Refractive index contours show decentration in some older lenses but individual variations mask age-related trends. Refractive index profiles along the optic axis have relatively flat central sections with distinct micro-fluctuations and a steep gradient in the cortex but do not exhibit an age-related trend. The refractive index profiles in the equatorial aspect show statistical significance with age, particularly for lenses below the age of sixty that had capacity to alter shape in vivo. The maximum refractive index in the lens centre decreases slightly with age with considerable scatter in the data and there are age-related variations in sagittal thickness and equatorial height. PMID:26416418

  20. H{sub 2}-He vibrational line-shape parameters: Measurement and semiclassical calculation

    SciTech Connect

    Forsman, J.W.; Bonamy, J.; Robert, D.; Berger, J.P.; Saint-Loup, R.; Berger, H.

    1995-10-01

    High-resolution inverse Raman spectroscopy has been used to obtain the line shifting and line broadening coefficients of H{sub 2} perturbed by He. Measurements have been made for the {ital Q}-branch transitions ({ital J}=0{r_arrow}5) in a density range of 10 to 20 amagat and from 296 to 995 K. Up to 795 K we have directly deduced from the experimental broadening coefficients the inelastic rotational state-to-state and vibrational dephasing rates. At higher temperatures, owing to the larger number of channels of relaxation which occur, the results have been analyzed using a scaling law. The line shift and broadening coefficients exhibit a square root and a linear dependence on temperature, respectively, and a significant {ital J} dependence. Semiclassical calculations based on an accurate {ital ab} {ital initio} potential lead to line-shape parameters consistent with experiment. They allow a clear understanding of their observed temperature dependence.

  1. Rotation parameters and shapes of 19 asteroids. Qualitative analysis and interpretation of data

    NASA Astrophysics Data System (ADS)

    Tungalag, N.; Shevchenko, V. G.; Lupishko, D. F.

    2003-10-01

    Using the combined method (amplitude-magnitude method plus the epoch method), we determined pole coordinates, sidereal rotation periods, senses of rotation and axial ratios of threeaxial ellipsoid figures for asteroids 158 Koronis, 167 Urda, 208 Lacrimosa, 211 Isolda, 263 Dresda, 268 Adorea, 277 Elvira, 311 Claudia, 321 Florentina, 344 Desiderata, 347 Pariana, 369 Aeria, 462 Eriphyla, 480 Hansa, 534 Nassovia, 631 Philippina, 720 Bohlina, 1223 Neckar, and 4954 Eric. For nine of them the determination was obtained for the first time. Using all available data on pole coordinates, sense of rotation and parameters of asteroid shapes, the qualitative analysis and interpretation of data on axis orientation, retrograde rotation and semi-axial ratios of asteroids were carried out.

  2. Simulation of dendritic growth reveals necessary and sufficient parameters to describe the shapes of dendritic trees

    NASA Astrophysics Data System (ADS)

    Trottier, Olivier; Ganguly, Sujoy; Bowne-Anderson, Hugo; Liang, Xin; Howard, Jonathon

    For the last 120 years, the development of neuronal shapes has been of great interest to the scientific community. Over the last 30 years, significant work has been done on the molecular processes responsible for dendritic development. In our ongoing research, we use the class IV sensory neurons of the Drosophila melanogaster larva as a model system to understand the growth of dendritic arbors. Our main goal is to elucidate the mechanisms that the neuron uses to determine the shape of its dendritic tree. We have observed the development of the class IV neuron's dendritic tree in the larval stage and have concluded that morphogenesis is defined by 3 distinct processes: 1) branch growth, 2) branching and 3) branch retraction. As the first step towards understanding dendritic growth, we have implemented these three processes in a computational model. Our simulations are able to reproduce the branch length distribution, number of branches and fractal dimension of the class IV neurons for a small range of parameters.

  3. Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers.

    PubMed

    Yu, Kai; Ge, Qi; Qi, H Jerry

    2014-01-01

    Shape memory polymers are at the forefront of recent materials research. Although the basic concept has been known for decades, recent advances in the research of shape memory polymers demand a unified approach to predict the shape memory performance under different thermo-temporal conditions. Here we report such an approach to predict the shape fixity and free recovery of thermo-rheologically simple shape memory polymers. The results show that the influence of programming conditions to free recovery can be unified by a reduced programming time that uniquely determines shape fixity, which consequently uniquely determines the shape recovery with a reduced recovery time. Furthermore, using the time-temperature superposition principle, shape recoveries under different thermo-temporal conditions can be extracted from the shape recovery under the reduced recovery time. Finally, a shape memory performance map is constructed based on a few simple standard polymer rheology tests to characterize the shape memory performance of the polymer. PMID:24423789

  4. Controllable pulse parameter transcranial magnetic stimulator with enhanced circuit topology and pulse shaping

    PubMed Central

    D’Ostilio, Kevin; Rothwell, John C; Murphy, David L

    2014-01-01

    Objective This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates several implementation and functionality advantages over conventional TMS devices and other devices with advanced pulse shape control. cTMS3 generates lower internal voltage differences and is implemented with transistors with lower voltage rating than prior cTMS devices. Main results cTMS3 provides more flexible pulse shaping since the circuit topology allows four coil-voltage levels during a pulse, including approximately zero voltage. The near-zero coil voltage enables snubbing of the ringing at the end of the pulse without the need for a separate active snubber circuit. cTMS3 can generate powerful rapid pulse sequences (<10 ms inter pulse interval) by increasing the width of each subsequent pulse and utilizing the large capacitor energy storage, allowing the implementation of paradigms such as paired-pulse and quadripulse TMS with a single pulse generation circuit. cTMS3 can also generate theta (50 Hz) burst stimulation with predominantly unidirectional electric field pulses. The cTMS3 device functionality and output strength are illustrated with electrical output measurements as well as a study of the effect of pulse width and polarity on the active motor threshold in 10 healthy volunteers. Significance The cTMS3 features could extend the utility of TMS as a research, diagnostic, and therapeutic tool. PMID:25242286

  5. Controllable pulse parameter transcranial magnetic stimulator with enhanced circuit topology and pulse shaping

    NASA Astrophysics Data System (ADS)

    Peterchev, Angel V.; DʼOstilio, Kevin; Rothwell, John C.; Murphy, David L.

    2014-10-01

    Objective. This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach. We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates several implementation and functionality advantages over conventional TMS devices and other devices with advanced pulse shape control. cTMS3 generates lower internal voltage differences and is implemented with transistors with a lower voltage rating than prior cTMS devices. Main results. cTMS3 provides more flexible pulse shaping since the circuit topology allows four coil-voltage levels during a pulse, including approximately zero voltage. The near-zero coil voltage enables snubbing of the ringing at the end of the pulse without the need for a separate active snubber circuit. cTMS3 can generate powerful rapid pulse sequences (\\lt 10 ms inter pulse interval) by increasing the width of each subsequent pulse and utilizing the large capacitor energy storage, allowing the implementation of paradigms such as paired-pulse and quadripulse TMS with a single pulse generation circuit. cTMS3 can also generate theta (50 Hz) burst stimulation with predominantly unidirectional electric field pulses. The cTMS3 device functionality and output strength are illustrated with electrical output measurements as well as a study of the effect of pulse width and polarity on the active motor threshold in ten healthy volunteers. Significance. The cTMS3 features could extend the utility of TMS as a research, diagnostic, and therapeutic tool.

  6. Shape memory alloy adaptive control of gas turbine engine compressor blade tip clearance

    NASA Astrophysics Data System (ADS)

    Schetky, Lawrence M.; Steinetz, Bruce M.

    1998-06-01

    The ambient air ingested through the inlet of a gas turbine is first compressed by an axial compressor followed by further compression in a centrifugal compressor and then fed into the combustion chamber where ignition and expansion take place to produce the engine thrust. The axial compressor typically has five or more stages which consist of revolving blades and stators and the overall performance of the turbine is strongly affected by the compressor efficiency. When the turbine is turned on, to accommodate the rapid initial increase in the compressor blade length due to centrifugal force, the cold turbine has a built in clearance between the turbine blade tip and the casing. As the turbine reached its operating temperature there is a further increase in the blade length due to thermal expansion and, at the same time, the diameter of the casing increases. The net result is that when these various components have reached their equilibrium temperatures, the initial cold build clearance is reduced, but there remains a residual clearance. The magnitude of this clearance has a direct effect on the compressor efficiency and can be stated as: Δη/Δ CLR equals 0.5 where η is efficiency and CLR is the tip clearance. The concept of adaptive tip clearance control is based on the ability of a shape memory alloy ring to shrink to a predetermined diameter when heated to the temperature of a particular stage, and thus reducing the tip clearance. The ring is fabricated from a CuAlNi shape memory alloy and is mounted in the casing so as to be coaxial with the rotating blades of the particular stage. When cold, the ring dimensions are such as to provide the required cold build clearance, but when at operating temperature the reduced diameter creates a very small tip clearance. The clearance provided by this concept is much smaller than the clearance normally obtained for a turbine of the size being studied.

  7. Self- and CO2-broadened line shape parameters for infrared bands of HDO

    NASA Astrophysics Data System (ADS)

    Smith, Mary-Ann H.; Malathy Devi, V.; Benner, D. Chris; Sung, Keeyoon; Mantz, Arlan W.; Gamache, Robert R.; Villanueva, Geronimo L.

    2015-11-01

    Knowledge of CO2-broadened HDO line widths and their temperature dependence is required to interpret infrared spectra of the atmospheres of Mars and Venus. However, this information is currently absent in most spectroscopic databases. We have analyzed nine high-resolution, high signal-to-noise spectra of HDO and HDO+CO2 mixtures to obtain broadening coefficients and other line shape parameters for transitions of the ν2 and ν3 vibrational bands located at 7.13 and 2.70 μm, respectively. The gas samples were prepared by mixing equal amounts of high-purity distilled H2O and 99% enriched D2O. The spectra were recorded at different temperatures (255-296 K) using a 20.38 cm long coolable cell [1] installed in the sample compartment of the Bruker IFS125HR Fourier transform spectrometer at the Jet Propulsion Laboratory in Pasadena, CA. The retrieved HDO spectroscopic parameters include line positions, intensities, self- and CO2-broadened half-width and pressure-induced shift coefficients and the temperature dependences for CO2 broadening. These spectroscopic parameters were obtained by simultaneous multispectrum fitting [2] of the same interval in all nine spectra. A non-Voigt line shape with speed dependence was applied. Line mixing was also observed for several transition pairs. Preliminary results compare well with the few other measurements reported in the literature.[1] K. Sung et al., J. Mol. Spectrosc. 162, 124-134 (2010).[2] D. C. Benner et al., J. Quant. Spectrosc. Radiat Transfer 53, 705-721 (1995).The research performed at the College of William and Mary was supported by NASA’s Mars Fundamental Research Program (Grant NNX13AG66G). The research at Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, Langley Research Center, and Goddard Space Flight Center was conducted under contracts and cooperative agreements with the National Aeronautics and Space Administration. RRG is pleased to acknowledge support of this study by the

  8. Shape, size and multiplicity of main-belt asteroids. I. Keck Adaptive Optics survey

    NASA Astrophysics Data System (ADS)

    Marchis, F.; Kaasalainen, M.; Hom, E. F. Y.; Berthier, J.; Enriquez, J.; Hestroffer, D.; Le Mignant, D.; de Pater, I.

    2006-11-01

    This paper presents results from a high spatial resolution survey of 33 main-belt asteroids with diameters >40 km using the Keck II Adaptive Optics (AO) facility. Five of these (45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra) were confirmed to have satellite. Assuming the same albedo as the primary, these moonlets are relatively small (˜5% of the primary size) suggesting that they are fragments captured after a disruptive collision of a parent body or captured ejecta due to an impact. For each asteroid, we have estimated the minimum size of a moonlet that can positively detected within the Hill sphere of the system by estimating and modeling a 2- σ detection profile: in average on the data set, a moonlet located at 2/100×R ( 1/4×R) with a diameter larger than 6 km (4 km) would have been unambiguously seen. The apparent size and shape of each asteroid was estimated after deconvolution using a new algorithm called AIDA. The mean diameter for the majority of asteroids is in good agreement with IRAS radiometric measurements, though for asteroids with a D<200 km, it is underestimated on average by 6-8%. Most asteroids had a size ratio that was very close to those determined by lightcurve measurements. One observation of 104 Klymene suggests it has a bifurcated shape. The bi-lobed shape of 121 Hermione described in Marchis et al. [Marchis, F., Hestroffer, D., Descamps, P., Berthier, J., Laver, C., de Pater, I., 2005c. Icarus 178, 450-464] was confirmed after deconvolution. The ratio of contact binaries in our survey, which is limited to asteroids larger than 40 km, is surprisingly high (˜6%), suggesting that a non-single configuration is common in the main-belt. Several asteroids have been analyzed with lightcurve inversions. We compared lightcurve inversion models for plane-of-sky predictions with the observed images (9 Metis, 52 Europa, 87 Sylvia, 130 Elektra, 192 Nausikaa, and 423 Diotima, 511 Davida). The AO images allowed us to determine a unique

  9. Shape, size and multiplicity of main-belt asteroids I. Keck Adaptive Optics survey

    PubMed Central

    Marchis, F.; Kaasalainen, M.; Hom, E.F.Y.; Berthier, J.; Enriquez, J.; Hestroffer, D.; Le Mignant, D.; de Pater, I.

    2008-01-01

    This paper presents results from a high spatial resolution survey of 33 main-belt asteroids with diameters >40 km using the Keck II Adaptive Optics (AO) facility. Five of these (45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra) were confirmed to have satellite. Assuming the same albedo as the primary, these moonlets are relatively small (∼5% of the primary size) suggesting that they are fragments captured after a disruptive collision of a parent body or captured ejecta due to an impact. For each asteroid, we have estimated the minimum size of a moonlet that can positively detected within the Hill sphere of the system by estimating and modeling a 2-σ detection profile: in average on the data set, a moonlet located at 2/100 × RHill (1/4 × RHill) with a diameter larger than 6 km (4 km) would have been unambiguously seen. The apparent size and shape of each asteroid was estimated after deconvolution using a new algorithm called AIDA. The mean diameter for the majority of asteroids is in good agreement with IRAS radiometric measurements, though for asteroids with a D < 200 km, it is underestimated on average by 6–8%. Most asteroids had a size ratio that was very close to those determined by lightcurve measurements. One observation of 104 Klymene suggests it has a bifurcated shape. The bi-lobed shape of 121 Hermione described in Marchis et al. [Marchis, F., Hestroffer, D., Descamps, P., Berthier, J., Laver, C., de Pater, I., 2005c. Icarus 178, 450–464] was confirmed after deconvolution. The ratio of contact binaries in our survey, which is limited to asteroids larger than 40 km, is surprisingly high (∼6%), suggesting that a non-single configuration is common in the main-belt. Several asteroids have been analyzed with lightcurve inversions. We compared lightcurve inversion models for plane-of-sky predictions with the observed images (9 Metis, 52 Europa, 87 Sylvia, 130 Elektra, 192 Nausikaa, and 423 Diotima, 511 Davida). The AO images allowed us to

  10. Multi-objective parameter optimization of common land model using adaptive surrogate modelling

    NASA Astrophysics Data System (ADS)

    Gong, W.; Duan, Q.; Li, J.; Wang, C.; Di, Z.; Dai, Y.; Ye, A.; Miao, C.

    2014-06-01

    Parameter specification usually has significant influence on the performance of land surface models (LSMs). However, estimating the parameters properly is a challenging task due to the following reasons: (1) LSMs usually have too many adjustable parameters (20-100 or even more), leading to the curse of dimensionality in the parameter input space; (2) LSMs usually have many output variables involving water/energy/carbon cycles, so that calibrating LSMs is actually a multi-objective optimization problem; (3) regional LSMs are expensive to run, while conventional multi-objective optimization methods needs a huge number of model runs (typically 105~106). It makes parameter optimization computationally prohibitive. An uncertainty qualification framework was developed to meet the aforementioned challenges: (1) use parameter screening to reduce the number of adjustable parameters; (2) use surrogate models to emulate the response of dynamic models to the variation of adjustable parameters; (3) use an adaptive strategy to promote the efficiency of surrogate modeling based optimization; (4) use a weighting function to transfer multi-objective optimization to single objective optimization. In this study, we demonstrate the uncertainty quantification framework on a single column case study of a land surface model - Common Land Model (CoLM) and evaluate the effectiveness and efficiency of the proposed framework. The result indicated that this framework can achieve optimal parameter set using totally 411 model runs, and worth to be extended to other large complex dynamic models, such as regional land surface models, atmospheric models and climate models.

  11. Silicone hydrogel contact lens surface analysis by atomic force microscopy: shape parameters

    NASA Astrophysics Data System (ADS)

    Giraldez, M. J.; Garcia-Resua, C.; Lira, M.; Sánchez-Sellero, C.; Yebra-Pimentel, E.

    2011-05-01

    Purpose: Average roughness (Ra) is generally used to quantify roughness; however it makes no distinction between spikes and troughs. Shape parameters as kurtosis (Rku) and skewness (Rsk) serve to distinguish between two profiles with the same Ra. They have been reported in many biomedical fields, but they were no applied to contact lenses before. The aim of this study is to analyze surface properties of four silicone hydrogel contact lenses (CL) by Atomic Force Microscopy (AFM) evaluating Ra, Rku and Rsk. Methods: CL used in this study were disposable silicone hydrogel senofilcon A, comfilcon A, balafilcon A and lotrafilcon B. Unworn CL surfaces roughness and topography were measured by AFM (Veeco, multimode-nanoscope V) in tapping modeTM. Ra, Rku and Rsk for 25 and 196 μm2 areas were determined. Results: Surface topography and parameters showed different characteristics depending on the own nature of the contact lens (Ra/Rku/Rsk for 25 and 196 μm2 areas were: senofilcon A 3,33/3,74/0,74 and 3,76/18,16/1,75; comfilcon A: 1,56/31,09/2,93 and 2,76/45,82/3,60; balafilcon A: 2,01/33,62/-2,14 and 2,54/23,36/-1,96; lotrafilcon B: 26,97/4,11/-0,34 and 29,25/2,82/-0,23). In lotrafilcon B, with the highest Ra, Rku showed a lower degree of peakedness of its distribution. Negative Rsk value obtained for balafilcon A showed a clear predominance of valleys in this lens. Conclusions: Kku and Rsk are two statistical parameters useful to analyse CL surfaces, which complete information from Ra. Differences in values distribution and symmetry were observed between CL.

  12. Object-adapted trapping and shape-tracking to probe a bacterial protein chain motor

    NASA Astrophysics Data System (ADS)

    Roth, Julian; Koch, Matthias; Rohrbach, Alexander

    2015-03-01

    The helical bacterium Spiroplasma is a motile plant and anthropod pathogen which swims by propagating pairs of kinks along its cell body. As a well suited model system for bacterial locomotion, understanding the cell's molecular motor is of vital interest also regarding the combat of bacterial diseases. The extensive deformations related to these kinks are caused by a contractile cytoskeletal protein ribbon representing a linear motor in contrast to common rotary motors as, e.g., flagella. We present new insights into the working of this motor through experiments with object-adapted optical traps and shape-tracking techniques. We use the given laser irradiation from the optical trap to hinder bacterial energy (ATP) production through the production of O2 radicals. The results are compared with experiments performed under the influence of an O2-Scavenger and ATP inhibitors, respectively. Our results show clear dependences of the kinking properties on the ATP concentration inside the bacterium. The experiments are supported by a theoretical model which we developed to describe the switching of the ribbon's protein subunits.

  13. Adaptive optical beam shaping for compensating projection-induced focus deformation

    NASA Astrophysics Data System (ADS)

    Pütsch, Oliver; Stollenwerk, Jochen; Loosen, Peter

    2016-02-01

    Scanner-based applications are already widely used for the processing of surfaces, as they allow for highly dynamic deflection of the laser beam. Particularly, the processing of three-dimensional surfaces with laser radiation initiates the development of highly innovative manufacturing techniques. Unfortunately, the focused laser beam suffers from deformation caused by the involved projection mechanisms. The degree of deformation is field variant and depends on both the surface geometry and the working position of the laser beam. Depending on the process sensitivity, the deformation affects the process quality, which motivates a method of compensation. Current approaches are based on a local adaption of the laser power to maintain constant intensity within the interaction zone. For advanced manufacturing, this approach is insufficient, as the residual deformation of the initial circular laser spot is not taken into account. In this paper, an alternative approach is discussed. Additional beam-shaping devices are integrated between the laser source and the scanner, and allow for an in situ compensation to ensure a field-invariant circular focus spot within the interaction zone. Beyond the optical design, the approach is challenging with respect to the control theory's point of view, as both the beam deflection and the compensation have to be synchronized.

  14. Adaptive RBF network for parameter estimation and stable air-fuel ratio control.

    PubMed

    Wang, Shiwei; Yu, D L

    2008-01-01

    In the application of variable structure control to engine air-fuel ratio, the ratio is subjected to chattering due to system uncertainty, such as unknown parameters or time varying dynamics. This paper proposes an adaptive neural network method to estimate two immeasurable physical parameters on-line and to compensate for the model uncertainty and engine time varying dynamics, so that the chattering is substantially reduced and the air-fuel ratio is regulated within the desired range of the stoichiometric value. The adaptive law of the neural network is derived using the Lyapunov method, so that the stability of the whole system and the convergence of the networks are guaranteed. Computer simulations based on a mean value engine model demonstrate the effectiveness of the technique. PMID:18166378

  15. Morphofunctional parameters and adaptation capabilities of students at the beginning of the third millennium.

    PubMed

    Negasheva, Marina A; Mishkova, T A

    2005-07-01

    On the basis of comprehensive anthropometrical observation of 1st and 2nd year students from different faculties of Moscow State University (MSU) carried out in 2002-2003, functional characteristics of the cardiovascular system (systolic and diastolic blood pressure, heart rate) were investigated in 205 young men and 327 young women along with traditional morphological parameters. In comparisons of contemporary young men and women with their peers, whose characteristics were obtained in the course of investigations carried out over the period 1920-1990, secular trends towards an increase of body length and a worsening of strength indices were detected. Evaluation and comparative analysis of adaptation capabilities of students were carried out based on screening and assessment of adaptation potential using the Bayevsky method (1987). It was shown that the parameters of physical development and the level of adaptation of an organism to environmental conditions can be used as additional markers for determination of the health status of contemporary students for early prevention of some diseases, improvement of their physical status and increase of adaptation potentials. PMID:16079587

  16. Identification of robust adaptation gene regulatory network parameters using an improved particle swarm optimization algorithm.

    PubMed

    Huang, X N; Ren, H P

    2016-01-01

    Robust adaptation is a critical ability of gene regulatory network (GRN) to survive in a fluctuating environment, which represents the system responding to an input stimulus rapidly and then returning to its pre-stimulus steady state timely. In this paper, the GRN is modeled using the Michaelis-Menten rate equations, which are highly nonlinear differential equations containing 12 undetermined parameters. The robust adaption is quantitatively described by two conflicting indices. To identify the parameter sets in order to confer the GRNs with robust adaptation is a multi-variable, multi-objective, and multi-peak optimization problem, which is difficult to acquire satisfactory solutions especially high-quality solutions. A new best-neighbor particle swarm optimization algorithm is proposed to implement this task. The proposed algorithm employs a Latin hypercube sampling method to generate the initial population. The particle crossover operation and elitist preservation strategy are also used in the proposed algorithm. The simulation results revealed that the proposed algorithm could identify multiple solutions in one time running. Moreover, it demonstrated a superior performance as compared to the previous methods in the sense of detecting more high-quality solutions within an acceptable time. The proposed methodology, owing to its universality and simplicity, is useful for providing the guidance to design GRN with superior robust adaptation. PMID:27323043

  17. Gaussian-to-top-hat beam shaping: an overview of parameters, methods, and applications

    NASA Astrophysics Data System (ADS)

    Homburg, O.; Mitra, T.

    2012-02-01

    Direct laser patterning of various materials is today widely used in several micro-system production lines like inkjet printing, solar cell technology, flat-panel display production, LEDs, OLEDs, semiconductors and medicine. Typically single-mode solid state lasers and their higher harmonics (e. g. 266, 355, 532 and 1064 nm) are used especially for machining of holes and grooves. The striking advantages of flat top intensity distributions compared to Gaussian beam profiles with respect to the efficiency and quality of these processes were already demonstrated. Here we will give an overview of parameters, methods and applications of Gaussian-to-top-hat beam shaping. The top hat field size can start from about 30 μm with no upper size limitation in the far field of the optics. Beam shaping for various wavelengths were realized with field geometries of squares, rectangles and circles. With LIMO's compact Gaussian-to-top-hat converter an inhomogeneity better than 5% contrast was reached. Special focus is put on the integration of Gaussian-to-top-hat beam shapers in fast scanning systems employing Galvo mirrors and a specially developed f-Theta lens to avoid destruction of the top hat profile within the scan field. Results with a 50x50μm2 top hat size (inhomogeneity down to <10%) in a scan area of 156x156mm² are presented. The minimal distortions of the top hat observed within the scan area make LIMO's compact Gaussian-to-top-hat converter excellently suited for industrial scanning applications, e.g. for the processing of solar panels.

  18. The effect of the shape parameters of a sample on the hydraulic conductivity

    NASA Astrophysics Data System (ADS)

    Kucza, Jarosław; Ilek, Anna

    2016-03-01

    The present study is a complement to the research investigating a laboratory method for measuring the saturated hydraulic conductivity of mountain forest soils, the results of which were presented in a paper by Ilek and Kucza (2014). The aim of the study is to analyse the influence of variation of particular cross-sections of samples and their enlarged side surface on the hydraulic conductivity measurement. The results show that a narrowing in the upper section of the sample results in an approximately twice lower disturbance of the laminar water flow than the narrowing occurring inside the sample. For that reason, the extent of the effect of the cross-section narrowing on the hydraulic conductivity measurement error is dependent on the location of the narrowing. An enlarged side surface of a sample, as described by the coefficient of side surface development, is on average 30% larger than the surface of a sample having the same volume and the same average cross-sectional area but a regular shape. The values of the coefficient of side surface development for a given sample were adopted in the range of 1.10-1.56. Among the shape parameters of the analysed irregular soil samples, the greatest impact on the measurement error is exerted by their enlarged lateral surface, which almost entirely explains the whole error of hydraulic conductivity measurement. The variability of successive cross-sectional areas of samples appears to be of marginal importance for the occurrence of this error, whose mean value was 1.15%.

  19. Stagnation Region Heat Transfer: The Influence of Turbulence Parameters, Reynolds Number and Body Shape

    NASA Technical Reports Server (NTRS)

    Vanfossen, G. James; Simoneau, Robert J.

    1994-01-01

    The effect of velocity gradient on stagnation region heat transfer augmentation by free stream turbulence was investigated. Heat transfer was measured in the stagnation region of four models with elliptical leading edges with ratios of major to minor axes of 1:1, 1.5:1, 2.25:1, and 3:1. Four geometrically similar, square bar, square mesh, biplane grids were used to generate free stream turbulence with different intensities and length. Heat transfer measurements were made for the following ranges of parameters: Reynolds number, based on leading edge diameter, 37,000 to 228,000; dimensionless leading edge velocity gradient, 1.20 to 1.80; turbulence intensity, 1.1 to 15.9%; and length scale to leading edge diameter ratio, 0.05 to 0.30. Stagnation point heat transfer augmentation by free stream turbulence can be predicted using a modified version of a previously developed correlation for a circular leading edge. Heat transfer augmentation was independent of body shape at the stagnation point. The heat transfer distribution down-stream from the stagnation point can be predicted using the normalized laminar heat transfer distribution.

  20. Characterization Of An EBL System: The Influence Of Process Parameters On Thickness Resist And Engraving Shapes

    SciTech Connect

    D'Urso, G.; Longo, M.; Ravasio, C.; Maccarini, G.

    2011-01-17

    In LIGA process, the low flexibility due to the use of masks might be overcome using the electron beam of a scansion electron microscope (SEM) instead of the synchrotron radiation. In this way, through the vector control of the beam, it is possible to irradiate a specific path on the resist without using any mask. Anyway, it is important to remark that the Electron Beam Lithography (EBL) can not include all the applications of the X-ray LIGA technique but it could be a valid alternative only for some specific uses. In particular, some limits concerning the impression of high thickness resists are expected. An EBL system based on a SEM was recently implemented by the authors and some tests were carried out to characterize the device performances. Aim of this work is to asses the system performances in terms of maximum impressible thickness resist and shape of the engraved entities. Several tests were carried out by varying the resist thickness and the process parameters.

  1. Dimension of model parameter space and operating characteristics in adaptive dose-finding studies.

    PubMed

    Iasonos, Alexia; Wages, Nolan A; Conaway, Mark R; Cheung, Ken; Yuan, Ying; O'Quigley, John

    2016-09-20

    Adaptive, model-based, dose-finding methods, such as the continual reassessment method, have been shown to have good operating characteristics. One school of thought argues in favor of the use of parsimonious models, not modeling all aspects of the problem, and using a strict minimum number of parameters. In particular, for the standard situation of a single homogeneous group, it is common to appeal to a one-parameter model. Other authors argue for a more classical approach that models all aspects of the problem. Here, we show that increasing the dimension of the parameter space, in the context of adaptive dose-finding studies, is usually counter productive and, rather than leading to improvements in operating characteristics, the added dimensionality is likely to result in difficulties. Among these are inconsistency of parameter estimates, lack of coherence in escalation or de-escalation, erratic behavior, getting stuck at the wrong level, and, in almost all cases, poorer performance in terms of correct identification of the targeted dose. Our conclusions are based on both theoretical results and simulations. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27090197

  2. Modern control concepts in hydrology. [parameter identification in adaptive stochastic control approach

    NASA Technical Reports Server (NTRS)

    Duong, N.; Winn, C. B.; Johnson, G. R.

    1975-01-01

    Two approaches to an identification problem in hydrology are presented, based upon concepts from modern control and estimation theory. The first approach treats the identification of unknown parameters in a hydrologic system subject to noisy inputs as an adaptive linear stochastic control problem; the second approach alters the model equation to account for the random part in the inputs, and then uses a nonlinear estimation scheme to estimate the unknown parameters. Both approaches use state-space concepts. The identification schemes are sequential and adaptive and can handle either time-invariant or time-dependent parameters. They are used to identify parameters in the Prasad model of rainfall-runoff. The results obtained are encouraging and confirm the results from two previous studies; the first using numerical integration of the model equation along with a trial-and-error procedure, and the second using a quasi-linearization technique. The proposed approaches offer a systematic way of analyzing the rainfall-runoff process when the input data are imbedded in noise.

  3. Annual Rainfall Maxima: Theoretical Estimation of the GEV Shape Parameter k Using Multifractal Models

    NASA Astrophysics Data System (ADS)

    Veneziano, D.; Langousis, A.; Lepore, C.

    2009-12-01

    The annual maximum of the average rainfall intensity in a period of duration d, Iyear(d), is typically assumed to have generalized extreme value (GEV) distribution. The shape parameter k of that distribution is especially difficult to estimate from either at-site or regional data, making it important to constraint k using theoretical arguments. In the context of multifractal representations of rainfall, we observe that standard theoretical estimates of k from extreme value (EV) and extreme excess (EE) theories do not apply, while estimates from large deviation (LD) theory hold only for very small d. We then propose a new theoretical estimator based on fitting GEV models to the numerically calculated distribution of Iyear(d). A standard result from EV and EE theories is that k depends on the tail behavior of the average rainfall in d, I(d). This result holds if Iyear(d) is the maximum of a sufficiently large number n of variables, all distributed like I(d); therefore its applicability hinges on whether n = 1yr/d is large enough and the tail of I(d) is sufficiently well known. One typically assumes that at least for small d the former condition is met, but poor knowledge of the upper tail of I(d) remains an obstacle for all d. In fact, in the case of multifractal rainfall, also the first condition is not met because, irrespective of d, 1yr/d is too small (Veneziano et al., 2009, WRR, in press). Applying large deviation (LD) theory to this multifractal case, we find that, as d → 0, Iyear(d) approaches a GEV distribution whose shape parameter kLD depends on a region of the distribution of I(d) well below the upper tail, is always positive (in the EV2 range), is much larger than the value predicted by EV and EE theories, and can be readily found from the scaling properties of I(d). The scaling properties of rainfall can be inferred also from short records, but the limitation remains that the result holds under d → 0 not for finite d. Therefore, for different reasons

  4. [Dynamic behavior of the adaptive control system, hypothalamus--anterior pituitary--adrenal cortex. Animal experimental study of the adequate system dynamics of the direct and indirect parameters of the adaptive control system].

    PubMed

    Zintzsch, I; Seidel, H; Lantzsch, C; Lantzsch, M

    1979-01-01

    The dynamic response of the adaptive closed-loop control system hypothalamus-anterior pituitary-adrenal cortex after application of short-time disturb pulses were examined experimentally in the pig. Blood sampling was performed biologically non-reactive by chronically implanted vascular catheters in the upper vena cava. A circadian biphase periodical dynamics characterizes the distrubance response of the adaptive control system, respectively, its direct and indirect parameters. After distrubance variables induced initial excess the plasma corticosteriods undershoot the basic level over a long period. Conversely, the dynamics of the eosinophils is determined through an initial eosinopenic phase and a subsequent typical overshoot. Periodical dynamic is absent in the steady state. The controller of the adaptive system does not show any spontaneous activity in the steady state without stress. The absence of an endogenic periodicity of the dependent parameters likewise gives evidence of an active oscillator. On the other hand, the controlling unit of the adaptive system constitutes a control response of circadian periodicty after activation by disturbance variables in pulse shape. The high damping of the control system terminates the transient state within 24 hours, and the corticosteriods and the eosinophils reach the steady state level. This control quality of the adaptive control system gains a high importance in the origination of the spontaneous circadian periodicity by corticosteriods and eosinophils and for the biological compensation of exogenous distrubance variables. PMID:233184

  5. Multi-objective parameter optimization of common land model using adaptive surrogate modeling

    NASA Astrophysics Data System (ADS)

    Gong, W.; Duan, Q.; Li, J.; Wang, C.; Di, Z.; Dai, Y.; Ye, A.; Miao, C.

    2015-05-01

    Parameter specification usually has significant influence on the performance of land surface models (LSMs). However, estimating the parameters properly is a challenging task due to the following reasons: (1) LSMs usually have too many adjustable parameters (20 to 100 or even more), leading to the curse of dimensionality in the parameter input space; (2) LSMs usually have many output variables involving water/energy/carbon cycles, so that calibrating LSMs is actually a multi-objective optimization problem; (3) Regional LSMs are expensive to run, while conventional multi-objective optimization methods need a large number of model runs (typically ~105-106). It makes parameter optimization computationally prohibitive. An uncertainty quantification framework was developed to meet the aforementioned challenges, which include the following steps: (1) using parameter screening to reduce the number of adjustable parameters, (2) using surrogate models to emulate the responses of dynamic models to the variation of adjustable parameters, (3) using an adaptive strategy to improve the efficiency of surrogate modeling-based optimization; (4) using a weighting function to transfer multi-objective optimization to single-objective optimization. In this study, we demonstrate the uncertainty quantification framework on a single column application of a LSM - the Common Land Model (CoLM), and evaluate the effectiveness and efficiency of the proposed framework. The result indicate that this framework can efficiently achieve optimal parameters in a more effective way. Moreover, this result implies the possibility of calibrating other large complex dynamic models, such as regional-scale LSMs, atmospheric models and climate models.

  6. A self-adaptive parameter optimization algorithm in a real-time parallel image processing system.

    PubMed

    Li, Ge; Zhang, Xuehe; Zhao, Jie; Zhang, Hongli; Ye, Jianwei; Zhang, Weizhe

    2013-01-01

    Aiming at the stalemate that precision, speed, robustness, and other parameters constrain each other in the parallel processed vision servo system, this paper proposed an adaptive load capacity balance strategy on the servo parameters optimization algorithm (ALBPO) to improve the computing precision and to achieve high detection ratio while not reducing the servo circle. We use load capacity functions (LC) to estimate the load for each processor and then make continuous self-adaptation towards a balanced status based on the fluctuated LC results; meanwhile, we pick up a proper set of target detection and location parameters according to the results of LC. Compared with current load balance algorithm, the algorithm proposed in this paper is proceeded under an unknown informed status about the maximum load and the current load of the processors, which means it has great extensibility. Simulation results showed that the ALBPO algorithm has great merits on load balance performance, realizing the optimization of QoS for each processor, fulfilling the balance requirements of servo circle, precision, and robustness of the parallel processed vision servo system. PMID:24174920

  7. - and Air-Broadened Line Shape Parameters of 12CH_4 : 4500-4620 CM-1

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda; Crawford, Timothy J.; Smith, Mary Ann H.; Mantz, Arlan; Predoi-Cross, Adriana

    2014-06-01

    Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. We report the self- and air-broadened Lorentz widths, shifts and line mixing coefficients along with their temperature dependences for methane absorption lines in the 2.2 μm spectral region. For this, we obtained a series of high-resolution, high S/N spectra of 99.99% 12C-enriched samples of pure methane and its dilute mixtures in dry air at cold temperatures down to 150 K using the Bruker IFS 125HR Fourier transform spectrometer at JPL. The coolable absorption cell had an optical path of 20.38 cm and was specially built to reside inside the sample compartment of the Bruker FTS. The 13 spectra used in the analysis consisted of seven pure 12CH_4 spectra at pressures from 4.5 to 169 Torr and six air-broadened spectra with total sample pressures of 113-300 Torr and methane volume mixing ratios between 4 and 9.7%. These 13 spectra were fit simultaneously using the multispectrum least-squares fitting technique. The results will be compared to existing values reported in the literature. K. Sung, A. W. Mantz, L. R. Brown, et al., J. Mol. Spectrosc., 162 (2010) 124-134. D. C. Benner, C. P. Rinsland, V. Malathy Devi, M. A. H. Smith and D. Atkins, JQSRT, 53 (1995) 705-721. Research described in this paper was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

  8. Rapid Computation of Thermodynamic Properties over Multidimensional Nonbonded Parameter Spaces Using Adaptive Multistate Reweighting.

    PubMed

    Naden, Levi N; Shirts, Michael R

    2016-04-12

    We show how thermodynamic properties of molecular models can be computed over a large, multidimensional parameter space by combining multistate reweighting analysis with a linear basis function approach. This approach reduces the computational cost to estimate thermodynamic properties from molecular simulations for over 130,000 tested parameter combinations from over 1000 CPU years to tens of CPU days. This speed increase is achieved primarily by computing the potential energy as a linear combination of basis functions, computed from either modified simulation code or as the difference of energy between two reference states, which can be done without any simulation code modification. The thermodynamic properties are then estimated with the Multistate Bennett Acceptance Ratio (MBAR) as a function of multiple model parameters without the need to define a priori how the states are connected by a pathway. Instead, we adaptively sample a set of points in parameter space to create mutual configuration space overlap. The existence of regions of poor configuration space overlap are detected by analyzing the eigenvalues of the sampled states' overlap matrix. The configuration space overlap to sampled states is monitored alongside the mean and maximum uncertainty to determine convergence, as neither the uncertainty or the configuration space overlap alone is a sufficient metric of convergence. This adaptive sampling scheme is demonstrated by estimating with high precision the solvation free energies of charged particles of Lennard-Jones plus Coulomb functional form with charges between -2 and +2 and generally physical values of σij and ϵij in TIP3P water. We also compute entropy, enthalpy, and radial distribution functions of arbitrary unsampled parameter combinations using only the data from these sampled states and use the estimates of free energies over the entire space to examine the deviation of atomistic simulations from the Born approximation to the solvation free

  9. Factors shaping the adaptive landscape for arboviruses: implications for the emergence of disease

    PubMed Central

    Coffey, Lark L; Forrester, Naomi; Tsetsarkin, Konstantin; Vasilakis, Nikos; Weaver, Scott C

    2013-01-01

    Many examples of the emergence or re-emergence of infectious diseases involve the adaptation of zoonotic viruses to new amplification hosts or to humans themselves. These include several instances of simple mutational adaptations, often to hosts closely related to the natural reservoirs. However, based on theoretical grounds, arthropod-borne viruses, or arboviruses, may face several challenges for adaptation to new hosts. Here, we review recent findings regarding adaptive evolution of arboviruses and its impact on disease emergence. We focus on the zoonotic alphaviruses Venezuelan equine encephalitis and chikungunya viruses, which have undergone adaptive evolution that mediated recent outbreaks of disease, as well as the flaviviruses dengue and West Nile viruses, which have emerged via less dramatic adaptive mechanisms. PMID:23374123

  10. A new adaptive control approach for aerospace vehicles with parameter uncertainties

    NASA Technical Reports Server (NTRS)

    Hahn, Yungsun; Speyer, Jason L.

    1989-01-01

    A new stochastic adaptive control structure is developed for the problem of combined parameter estimation and control of aerospace vehicles with changing parameters. Parameter uncertainties are modeled as first-order Gauss-Markov processes, and are introduced to the system dynamics through a small parameter. It is assumed that an accurate inertial measurement unit gives perfect measurements of the state variables. Since the stochastic system is assumed to be Gauss-Markov, the density function of the parameters given these measurements is conditionally Gaussian. Based on this conditionally Gaussian density, the problem of minimizing a quadratic cost over an infinite time horizon can be set up within the framework of stochastic optimal control theory. The optimal feedback control law is derived from a straightforward expansion of the Hamilton-Jacobi-Bellman equation, based on the LQG solution. The resulting nonlinear controller is applied to the pitch axis control of a space platform with uncertain moments of inertia and is shown to produce marked improvement over a fixed controller.

  11. FK506 binding protein 51 integrates pathways of adaptation: FKBP51 shapes the reactivity to environmental change.

    PubMed

    Rein, Theo

    2016-09-01

    This review portraits FK506 binding protein (FKBP) 51 as "reactivity protein" and collates recent publications to develop the concept of FKBP51 as contributor to different levels of adaptation. Adaptation is a fundamental process that enables unicellular and multicellular organisms to adjust their molecular circuits and structural conditions in reaction to environmental changes threatening their homeostasis. FKBP51 is known as chaperone and co-chaperone of heat shock protein (HSP) 90, thus involved in processes ensuring correct protein folding in response to proteotoxic stress. In mammals, FKBP51 both shapes the stress response and is calibrated by the stress levels through an ultrashort molecular feedback loop. More recently, it has been linked to several intracellular pathways related to the reactivity to drug exposure and stress. Through its role in autophagy and DNA methylation in particular it influences adaptive pathways, possibly also in a transgenerational fashion. Also see the video abstract here. PMID:27374865

  12. Integration of Online Parameter Identification and Neural Network for In-Flight Adaptive Control

    NASA Technical Reports Server (NTRS)

    Hageman, Jacob; Smith, Mark; Stachowiak, Susan

    2003-01-01

    An indirect adaptive system has been constructed for robust control of an aircraft with uncertain aerodynamic characteristics. This system consists of a multilayer perceptron pre-trained neural network, online stability and control derivative identification, a dynamic cell structure online learning neural network, and a model following control system based on the stochastic optimal feedforward and feedback technique. The pre-trained neural network and model following control system have been flight-tested, but the online parameter identification and online learning neural network are new additions used for in-flight adaptation of the control system model. A description of the modification and integration of these two stand-alone software packages into the complete system in preparation for initial flight tests is presented. Open-loop results using both simulation and flight data, as well as closed-loop performance of the complete system in a nonlinear, six-degree-of-freedom, flight validated simulation, are analyzed. Results show that this online learning system, in contrast to the nonlearning system, has the ability to adapt to changes in aerodynamic characteristics in a real-time, closed-loop, piloted simulation, resulting in improved flying qualities.

  13. Inquiry in Interaction: How Local Adaptations of Curricula Shape Classroom Communities

    ERIC Educational Resources Information Center

    Enyedy, Noel; Goldberg, Jennifer

    2004-01-01

    In this study, we seek a better understanding of how individuals and their daily interactions shape and reshape social structures that constitute a classroom community. Moreover, we provide insight into how discourse and classroom interactions shape the nature of a learning community, as well as which aspects of the classroom culture may be…

  14. NEUTRON-PROTON EFFECTIVE RANGE PARAMETERS AND ZERO-ENERGY SHAPE DEPENDENCE.

    SciTech Connect

    HACKENBURG, R.W.

    2005-06-01

    A completely model-independent effective range theory fit to available, unpolarized, np scattering data below 3 MeV determines the zero-energy free proton cross section {sigma}{sub 0} = 20.4287 {+-} 0.0078 b, the singlet apparent effective range r{sub s} = 2.754 {+-} 0.018{sub stat} {+-} 0.056{sub syst} fm, and improves the error slightly on the parahydrogen coherent scattering length, a{sub c} = -3.7406 {+-} 0.0010 fm. The triplet and singlet scattering lengths and the triplet mixed effective range are calculated to be a{sub t} = 5.4114 {+-} 0.0015 fm, a{sub s} = -23.7153 {+-} 0.0043 fm, and {rho}{sub t}(0,-{epsilon}{sub t}) = 1.7468 {+-} 0.0019 fm. The model-independent analysis also determines the zero-energy effective ranges by treating them as separate fit parameters without the constraint from the deuteron binding energy {epsilon}{sub t}. These are determined to be {rho}{sub t}(0,0) = 1.705 {+-} 0.023 fm and {rho}{sub s}(0,0) = 2.665 {+-} 0.056 fm. This determination of {rho}{sub t}(0,0) and {rho}{sub s}(0,0) is most sensitive to the sparse data between about 20 and 600 keV, where the correlation between the determined values of {rho}{sub t}(0,0) and {rho}{sub s}(0,0) is at a minimum. This correlation is responsible for the large systematic error in r{sub s}. More precise data in this range are needed. The present data do not event determine (with confidence) that {rho}{sub t}(0,0) {ne} {rho}{sub t}(0, -{epsilon}{sub t}), referred to here as ''zero-energy shape dependence''. The widely used measurement of {sigma}{sub 0} = 20.491 {+-} 0.014 b from W. Dilg, Phys. Rev. C 11, 103 (1975), is argued to be in error.

  15. Line Positions, Intensities And Line Shape Parameters Of PH3 Near 4.4 µm

    NASA Astrophysics Data System (ADS)

    Venkataraman, Malathy; Benner, D. C.; Kleiner, I.; Brown, L. R.; Sams, R. L.; Fletcher, L. N.

    2012-10-01

    Accurate knowledge of spectral line parameters in the 2000 to 2400 cm-1 region of PH3 is important for the CASSINI/VIMS exploration of dynamics and chemistry of Saturn and for the correct interpretation of future Jovian observations by JUNO and ESA’s newly-selected mission JUICE. Since the available intensity information for phosphine is inconsistent, we measured line positions and intensities for over 4000 individual transitions in the 2ν2, ν2+ν4, 2ν4, ν1 and the ν3 bands from analyzing high-resolution, high S/N spectra recorded at room temperature using two Fourier transform spectrometers (FTS); the Bruker IFS 125 HR FTS at PNNL and the Kitt Peak FTS at the National Solar Observatory in Arizona. In addition to line positions and intensities, self-broadened half width and self-induced pressure-shift coefficients were also measured for about 800 transitions for the various bands. The strong Coriolis and other types of interactions occurring among the various vibrational levels result in a large number of forbidden transitions as well as cause A+A- splittings in transitions with K″ that are multiples of 3. Line mixing was detected between several A+A- pairs of transitions; and self- line mixing coefficients were measured for several such pairs of transitions by applying the off-diagonal relaxation matrix formalism of Levy et al.1 A multispectrum nonlinear least squares technique2 employing a non-Voigt line shape including line mixing and speed dependence was used in fitting all the spectra simultaneously. Present results are compared with other reported values. This research is supported by NASA’s Outer Planets Research Program. References [1] A. Lévy et al., In “Spectroscopy of the Earth’s Atmosphere and Interstellar Medium”, Ed. K, Narahari Rao and A. Weber, Boston, Academic Press; p, 261-337 (1992). [2] D. C. Benner et al., J Quant. Spectrosc. Radiat. Transfer 53, 705, 1995.

  16. Analysis of luminosity distributions and the shape parameters of strong gravitational lensing elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Biernaux, J.; Magain, P.; Sluse, D.; Chantry, V.

    2016-01-01

    Context. The luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like and diffuse, around the lensing galaxy. Those objects limit the study of the galaxy luminosity to its inner parts. Therefore, the usual fitting methods perform rather badly on such images. Previous studies of strong lenses luminosity profiles using software such as GALFIT or IMFITFITS and various PSF-determining methods have resulted in somewhat discrepant results. Aims: The present work aims at investigating the causes of those discrepancies, as well as at designing more robust techniques for studying the morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. Methods: We design a new method to independently measure each shape parameter, namely, the position angle, ellipticity, and half-light radius of the galaxy. Our half-light radius measurement method is based on an innovative scheme for computing isophotes that is well suited to measuring the morphological properties of gravititational lensing galaxies. Its robustness regarding various specific aspects of gravitational lensing image processing is analysed and tested against GALFIT. It is then applied to a sample of systems from the CASTLES database. Results: Simulations show that, when restricted to small, inner parts of the lensing galaxy, the technique presented here is more trustworthy than GALFIT. It gives more robust results than GALFIT, which shows instabilities regarding the fitting region, the value of the Sérsic index, and the signal-to-noise ratio. It is therefore better suited than GALFIT for gravitational lensing galaxies. It is also able to study lensing galaxies that are not much larger than the PSF. New values for the half-light radius of the objects in our sample are presented and compared to previous works. Table 6 is only available

  17. A method of simultaneously measuring particle shape parameter and aerodynamic size

    NASA Astrophysics Data System (ADS)

    Ding, Lei; Zhang, JinBi; Zheng, HaiYang; Wang, YingPing; Fang, Li

    2016-08-01

    For the purpose of classification of airborne particles, this paper describes an experimental apparatus for simultaneously measuring shape characteristics and aerodynamic size at single particle level. The shape of a particle is indicated through near forward scattering light collected by 3 PMTs placed at 120-degree offset azimuthal angles and the aerodynamic diameter is obtained by time-of-flight that a particle takes to traverse double laser beams. Laboratory experiments are performed on sampled aerosol particles in spherical, cuboid and elongated shape, and preliminary results indicate that the experimental apparatus has a good capability of discriminating between spherical and irregular particles. A variance factor of scattered light related to shape of ambient airborne particles under different conditions are also presented, which can be modeled using lognormal probability density distribution. Combined with aerodynamic size information, these results suggest potential uses in environmental aerosol monitoring for characterizing constituents of particles.

  18. Symmetry-controlled colloidal nanocrystals: nonhydrolytic chemical synthesis and shape determining parameters.

    PubMed

    Jun, Young-wook; Lee, Jae-Hyun; Choi, Jin-sil; Cheon, Jinwoo

    2005-08-11

    Since inorganic nanocrystals exhibit unique shape-dependent nanoscale properties and can be utilized as basic building blocks for futuristic nanodevices, a systematic study on the shape control of these nanocrystals remains an important subject in materials and physical chemistry. In this feature article, we overview the recent progress on the synthetic development of symmetry-controlled colloidal nanocrystals of semiconductor and metal oxide, which are prepared through nonhydrolytic chemical routes. We describe their shape-guiding processes and illustrate the detailed key factors controlling their growth by examining various case studies of zero-dimensional spheres and cubes, one-dimensional rods, and quasi multidimensional structures such as disks, multipods, and stars. Specifically, the crystalline phase of nucleating seeds, surface energy, kinetic vs thermodynamic growth, and selective adhesion processes of capping ligands are found to be most crucial for the determination of the nanocrystal shape. PMID:16852873

  19. Adaptive nonlinear observer for state and unknown parameter estimation in noisy systems

    NASA Astrophysics Data System (ADS)

    Vijayaraghavan, Krishna; Valibeygi, Amir

    2016-01-01

    This paper proposes a novel adaptive observer for Lipschitz nonlinear systems and dissipative nonlinear systems in the presence of disturbances and sensor noise. The observer is based on an H∞ observer that can estimate both the system states and unknown parameters by minimising a cost function consisting of the sum of the square integrals of the estimation errors in the states and unknown parameters. The paper presents necessary and sufficient conditions for the existence of the observer, and the equations for determining observer gains are formulated as linear matrix inequalities (LMIs) that can be solved offline using commercially available LMI solvers. The observer design has also been extended to the case of time-varying unknown parameters. The use of the observer is demonstrated through illustrative examples and the performance is compared with extended Kalman filtering. Compared to previous results on nonlinear observers, the proposed observer is more computationally efficient, and guarantees state and parameter estimation for two very broad classes of nonlinear systems (Lipschitz and dissipative nonlinear systems) in the presence of input disturbances and sensor noise. In addition, the proposed observer does not require online computation of the observer gain.

  20. Determination of remodeling parameters for a strain-adaptive finite element model of the distal ulna.

    PubMed

    Neuert, Mark A C; Dunning, Cynthia E

    2013-09-01

    Strain energy-based adaptive material models are used to predict bone resorption resulting from stress shielding induced by prosthetic joint implants. Generally, such models are governed by two key parameters: a homeostatic strain-energy state (K) and a threshold deviation from this state required to initiate bone reformation (s). A refinement procedure has been performed to estimate these parameters in the femur and glenoid; this study investigates the specific influences of these parameters on resulting density distributions in the distal ulna. A finite element model of a human ulna was created using micro-computed tomography (µCT) data, initialized to a homogeneous density distribution, and subjected to approximate in vivo loading. Values for K and s were tested, and the resulting steady-state density distribution compared with values derived from µCT images. The sensitivity of these parameters to initial conditions was examined by altering the initial homogeneous density value. The refined model parameters selected were then applied to six additional human ulnae to determine their performance across individuals. Model accuracy using the refined parameters was found to be comparable with that found in previous studies of the glenoid and femur, and gross bone structures, such as the cortical shell and medullary canal, were reproduced. The model was found to be insensitive to initial conditions; however, a fair degree of variation was observed between the six specimens. This work represents an important contribution to the study of changes in load transfer in the distal ulna following the implementation of commercial orthopedic implants. PMID:23804949

  1. Evolution of opercle shape in cichlid fishes from Lake Tanganyika - adaptive trait interactions in extant and extinct species flocks

    PubMed Central

    Wilson, Laura A. B.; Colombo, Marco; Sánchez-Villagra, Marcelo R.; Salzburger, Walter

    2015-01-01

    Phenotype-environment correlations and the evolution of trait interactions in adaptive radiations have been widely studied to gain insight into the dynamics underpinning rapid species diversification. In this study we explore the phenotype-environment correlation and evolution of operculum shape in cichlid fishes using an outline-based geometric morphometric approach combined with stable isotope indicators of macrohabitat and trophic niche. We then apply our method to a sample of extinct saurichthyid fishes, a highly diverse and near globally distributed group of actinopterygians occurring throughout the Triassic, to assess the utility of extant data to inform our understanding of ecomorphological evolution in extinct species flocks. A series of comparative methods were used to analyze shape data for 54 extant species of cichlids (N = 416), and 6 extinct species of saurichthyids (N = 44). Results provide evidence for a relationship between operculum shape and feeding ecology, a concentration in shape evolution towards present along with evidence for convergence in form, and significant correlation between the major axes of shape change and measures of gut length and body elongation. The operculum is one of few features that can be compared in extant and extinct groups, enabling reconstruction of phenotype-environment interactions and modes of evolutionary diversification in deep time. PMID:26584885

  2. Evolution of opercle shape in cichlid fishes from Lake Tanganyika - adaptive trait interactions in extant and extinct species flocks.

    PubMed

    Wilson, Laura A B; Colombo, Marco; Sánchez-Villagra, Marcelo R; Salzburger, Walter

    2015-01-01

    Phenotype-environment correlations and the evolution of trait interactions in adaptive radiations have been widely studied to gain insight into the dynamics underpinning rapid species diversification. In this study we explore the phenotype-environment correlation and evolution of operculum shape in cichlid fishes using an outline-based geometric morphometric approach combined with stable isotope indicators of macrohabitat and trophic niche. We then apply our method to a sample of extinct saurichthyid fishes, a highly diverse and near globally distributed group of actinopterygians occurring throughout the Triassic, to assess the utility of extant data to inform our understanding of ecomorphological evolution in extinct species flocks. A series of comparative methods were used to analyze shape data for 54 extant species of cichlids (N = 416), and 6 extinct species of saurichthyids (N = 44). Results provide evidence for a relationship between operculum shape and feeding ecology, a concentration in shape evolution towards present along with evidence for convergence in form, and significant correlation between the major axes of shape change and measures of gut length and body elongation. The operculum is one of few features that can be compared in extant and extinct groups, enabling reconstruction of phenotype-environment interactions and modes of evolutionary diversification in deep time. PMID:26584885

  3. Molecular Specificity, Convergence and Constraint Shape Adaptive Evolution in Nutrient-Poor Environments

    PubMed Central

    Hong, Jungeui; Gresham, David

    2014-01-01

    One of the central goals of evolutionary biology is to explain and predict the molecular basis of adaptive evolution. We studied the evolution of genetic networks in Saccharomyces cerevisiae (budding yeast) populations propagated for more than 200 generations in different nitrogen-limiting conditions. We find that rapid adaptive evolution in nitrogen-poor environments is dominated by the de novo generation and selection of copy number variants (CNVs), a large fraction of which contain genes encoding specific nitrogen transporters including PUT4, DUR3 and DAL4. The large fitness increases associated with these alleles limits the genetic heterogeneity of adapting populations even in environments with multiple nitrogen sources. Complete identification of acquired point mutations, in individual lineages and entire populations, identified heterogeneity at the level of genetic loci but common themes at the level of functional modules, including genes controlling phosphatidylinositol-3-phosphate metabolism and vacuole biogenesis. Adaptive strategies shared with other nutrient-limited environments point to selection of genetic variation in the TORC1 and Ras/PKA signaling pathways as a general mechanism underlying improved growth in nutrient-limited environments. Within a single population we observed the repeated independent selection of a multi-locus genotype, comprised of the functionally related genes GAT1, MEP2 and LST4. By studying the fitness of individual alleles, and their combination, as well as the evolutionary history of the evolving population, we find that the order in which these mutations are acquired is constrained by epistasis. The identification of repeatedly selected variation at functionally related loci that interact epistatically suggests that gene network polymorphisms (GNPs) may be a frequent outcome of adaptive evolution. Our results provide insight into the mechanistic basis by which cells adapt to nutrient-limited environments and suggest that

  4. Invisible cloak design with controlled constitutive parameters and arbitrary shaped boundaries through Helmholtz's equation: comment.

    PubMed

    Chang, Zheng; Zhou, Xiaoming; Hu, Jin; Hu, Gengkai

    2010-02-15

    In a recent paper, Chen et al. [Opt. Express 17, 3581 (2009)] develop an approach to design invisible cloaks with controllable constitutive parameters by adjusting the constant k in the Helmholtz's equation. In this comment, we discuss the limitation of the free parameter k in designing cloaks. It is found that the real constant k can be chosen only as limited values in order to avoid the singular material parameters. PMID:20389403

  5. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    SciTech Connect

    Zarepisheh, M; Li, R; Xing, L; Ye, Y; Boyd, S

    2014-06-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  6. Adaptation of model parameters of a rail model at measured rail compliances

    NASA Astrophysics Data System (ADS)

    Ripke, B.

    1992-01-01

    A method for calculation of unknown parameters of a rail model is presented. Measurements were carried out on a test rail of a locomotive factory by means of pulse excitation. Accelerations of the rail head in the vertical and laterial directions were measured with an accelerometer and dilatations were measured as a function of rail flexion with a piezo film. Input and transfer compliances were measured. The obtained data were controlled by means of a fast Fourier transformation analyzer and recorded on magnetic tapes. A model was developed with the finite element method by considering the rail as a Timoshinko beam. Stiffness and damping of bulkhead and tiebar were obtained. A variable threshold mass was introduced for model adaptation to the experiment results in low frequency area.

  7. A Computational Approach to Model Vascular Adaptation During Chronic Hemodialysis: Shape Optimization as a Substitute for Growth Modeling

    NASA Astrophysics Data System (ADS)

    Mahmoudzadeh Akherat, S. M. Javid; Boghosian, Michael; Cassel, Kevin; Hammes, Mary

    2015-11-01

    End-stage-renal disease patients depend on successful long-term hemodialysis via vascular access, commonly facilitated via a Brachiocephalic Fistula (BCF). The primary cause of BCF failure is Cephalic Arch Stenosis (CAS). It is believed that low Wall Shear Stress (WSS) regions, which occur because of the high flow rates through the natural bend in the cephalic vein, create hemodynamic circumstances that trigger the onset and development of Intimal Hyperplasia (IH) and subsequent CAS. IH is hypothesized to be a natural effort to reshape the vessel, aiming to bring the WSS values back to a physiologically acceptable range. We seek to explore the correlation between regions of low WSS and subsequent IH and CAS in patient-specific geometries. By utilizing a shape optimization framework, a method is proposed to predict cardiovascular adaptation that could potentially be an alternative to vascular growth and remodeling. Based on an objective functional that seeks to alter the vessel shape in such a way as to readjust the WSS to be within the normal physiological range, CFD and shape optimization are then coupled to investigate whether the optimal shape evolution is correlated with actual patient-specific geometries thereafter. Supported by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (R01 DK90769).

  8. Surface-enhanced Raman spectroscopy-active substrates: adapting the shape of plasmonic nanoparticles for different biological applications.

    PubMed

    Vitol, Elina A; Friedman, Gary; Gogotsi, Yury

    2014-04-01

    We discuss the relationship between the shape of plasmonic nanoparticles and the biological surface-enhanced Raman spectroscopy (SERS) applications which they can enable. As a step forward in developing SERS-active substrates adapted to a particular application, we demonstrate that a modification of the widely used protocol for the sodium citrate mediated reduction of chloroauric acid, which is typically employed only for obtaining spherical gold nanoparticles, can yield flat polygonal nanoparticles at room temperature and a decreased amount of the reducing agent. The significant advantage of the described approach is that it allows for synthesis of nanoparticles with different geometries using a well-established synthesis protocol without the need for any additional chemicals or special synthesis apparatus. By contrasting spherical and anisotropically shaped nanoparticles, we demonstrate that multifaceted nanoparticles with sharp edges are better suitable for SERS analysis of low concentration analytes requiring strong SERS enhancement. On the other hand, gold nanoparticles with isotropic shapes, while giving a smaller enhancement, can provide a more reproducible SERS signal. This is important for analytical applications of complex biological systems where large SERS enhancement may not always be required, whereas data reproducibility and minimal false positive rate are imperative. Using a SERS-active substrate comprising isotropically shaped gold nanoparticles, we demonstrate the differences between Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, attributable to the outer membrane and peptidoglycan layer, with the level of detail which has not been previously reported with optical spectroscopic techniques. PMID:24734732

  9. Susceptibility to a metal under global warming is shaped by thermal adaptation along a latitudinal gradient.

    PubMed

    Dinh Van, Khuong; Janssens, Lizanne; Debecker, Sara; De Jonge, Maarten; Lambret, Philippe; Nilsson-Örtman, Viktor; Bervoets, Lieven; Stoks, Robby

    2013-09-01

    Global warming and contamination represent two major threats to biodiversity that have the potential to interact synergistically. There is the potential for gradual local thermal adaptation and dispersal to higher latitudes to mitigate the susceptibility of organisms to contaminants and global warming at high latitudes. Here, we applied a space-for-time substitution approach to study the thermal dependence of the susceptibility of Ischnura elegans damselfly larvae to zinc in a common garden warming experiment (20 and 24 °C) with replicated populations from three latitudes spanning >1500 km in Europe. We observed a striking latitude-specific effect of temperature on the zinc-induced mortality pattern; local thermal adaptation along the latitudinal gradient made Swedish, but not French, damselfly larvae more susceptible to zinc at 24 °C. Latitude- and temperature-specific differences in zinc susceptibility may be related to the amount of energy available to defend against and repair damage since Swedish larvae showed a much stronger zinc-induced reduction of food intake at 24 °C. The pattern of local thermal adaptation indicates that the predicted temperature increase of 4 °C by 2100 will strongly magnify the impact of a contaminant such as zinc at higher latitudes unless there is thermal evolution and/or migration of lower latitude genotypes. Our results underscore the critical importance of studying the susceptibility to contaminants under realistic warming scenarios taking into account local thermal adaptation across natural temperature gradients. PMID:23640735

  10. Fluidic origami: a plant-inspired adaptive structure with shape morphing and stiffness tuning

    NASA Astrophysics Data System (ADS)

    Li, Suyi; Wang, K. W.

    2015-10-01

    Inspired by the physics behind the rapid plant movements and the rich topologies in origami folding, this research creates a unique class of multi-functional adaptive structure through exploring the innovation of fluidic origami. The idea is to connect multiple Miura folded sheets along their crease lines into a space-filling structure, and fill the tubular cells in-between with working fluids. The pressure and fluid flow in these cells can be strategically controlled much like in plants for nastic movements. The relationship between the internal fluid volume and the overall structure deformation is primarily determined by the kinematics of folding. This relationship can be exploited so that fluidic origami can achieve actuation/morphing by actively changing the internal fluid volume, and stiffness tuning by constraining the fluid volume. In order to characterize the working principles and performance potentials of these two adaptive functions, this research develops an equivalent truss frame model on a fluidic origami unit cell to analyze its fundamental elastic characteristics. Eigen-stiffness analysis based on this model reveals the primary modes of deformation and their relationships with initial folding configurations. Performances of the adaptive functions are correlated to the crease pattern design. In parallel to analytical studies, the feasibility of the morphing and stiffness tuning is also examined experimentally via a 3D printed multi-material prototype demonstrator. The research reported in this paper could lead to the synthesis of adaptive fluidic origami cellular metastructures or metamaterial systems for various engineering applications.

  11. Shaping the Cities of Tomorrow: Integrating Local Urban Adaptation within an Environmental Framework

    NASA Astrophysics Data System (ADS)

    Georgescu, M.

    2014-12-01

    Contemporary methods focused on increasing urban sustainability are largely based on the reduction of greenhouse gas emissions. While these efforts are essential steps forward, continued characterization of urban sustainability solely within a biogeochemical framework, with neglect of the biophysical impact of the built environment, omits regional hydroclimatic forcing of the same order of magnitude as greenhouse gas emissions. Using a suite of continuous, multi-year and multi-member continental scale numerical simulations with the WRF model for the U.S., we examine hydroclimatic impacts for a variety of U.S. urban expansion scenarios (for the year 2100) and urban adaptation futures (cool roofs, green roofs, and a hypothetical hybrid approach integrating biophysical properties of both cool and green roofs), and compare those to experiments utilizing a contemporary urban extent. Widespread adoption of adaptation strategies exhibits regionally and seasonally dependent hydroclimatic impacts. For some regions and seasons, urban-induced warming in excess of 3°C can be completely offset by all adaptation approaches examined. For other regions, widespread adoption of some adaptation approaches leads to significant rainfall decline. Sustainable urban expansion therefore requires an integrated assessment that also incorporates biophysically induced urban impacts, and demands tradeoff assessment of various strategies aimed to ameliorate deleterious consequences of growth (e.g., urban heat island reduction).

  12. Adaptive Aft Signature Shaping of a Low-Boom Supersonic Aircraft Using Off-Body Pressures

    NASA Technical Reports Server (NTRS)

    Ordaz, Irian; Li, Wu

    2012-01-01

    The design and optimization of a low-boom supersonic aircraft using the state-of-the- art o -body aerodynamics and sonic boom analysis has long been a challenging problem. The focus of this paper is to demonstrate an e ective geometry parameterization scheme and a numerical optimization approach for the aft shaping of a low-boom supersonic aircraft using o -body pressure calculations. A gradient-based numerical optimization algorithm that models the objective and constraints as response surface equations is used to drive the aft ground signature toward a ramp shape. The design objective is the minimization of the variation between the ground signature and the target signature subject to several geometric and signature constraints. The target signature is computed by using a least-squares regression of the aft portion of the ground signature. The parameterization and the deformation of the geometry is performed with a NASA in- house shaping tool. The optimization algorithm uses the shaping tool to drive the geometric deformation of a horizontal tail with a parameterization scheme that consists of seven camber design variables and an additional design variable that describes the spanwise location of the midspan section. The demonstration cases show that numerical optimization using the state-of-the-art o -body aerodynamic calculations is not only feasible and repeatable but also allows the exploration of complex design spaces for which a knowledge-based design method becomes less effective.

  13. Parental antagonism and parent–offspring co-adaptation interact to shape family life

    PubMed Central

    Meunier, Joël; Kölliker, Mathias

    2012-01-01

    The family is an arena for conflicts between offspring, mothers and fathers that need resolving to promote the evolution of parental care and the maintenance of family life. Co-adaptation is known to contribute to the resolution of parent–offspring conflict over parental care by selecting for combinations of offspring demand and parental supply that match to maximize the fitness of family members. However, multiple paternity and differences in the level of care provided by mothers and fathers can generate antagonistic selection on offspring demand (mediated, for example, by genomic imprinting) and possibly hamper co-adaptation. While parent–offspring co-adaptation and parental antagonism are commonly considered two major processes in the evolution of family life, their co-occurrence and the evolutionary consequences of their joint action are poorly understood. Here, we demonstrate the simultaneous and entangled effects of these two processes on outcomes of family interactions, using a series of breeding experiments in the European earwig, Forficula auricularia, an insect species with uniparental female care. As predicted from parental antagonism, we show that paternally inherited effects expressed in offspring influence both maternal care and maternal investment in future reproduction. However, and as expected from the entangled effects of parental antagonism and co-adaptation, these effects critically depended on postnatal interactions with caring females and maternally inherited effects expressed in offspring. Our results demonstrate that parent–offspring co-adaptation and parental antagonism are entangled key drivers in the evolution of family life that cannot be fully understood in isolation. PMID:22810433

  14. Multiobjective adaptive surrogate modeling-based optimization for parameter estimation of large, complex geophysical models

    NASA Astrophysics Data System (ADS)

    Gong, Wei; Duan, Qingyun; Li, Jianduo; Wang, Chen; Di, Zhenhua; Ye, Aizhong; Miao, Chiyuan; Dai, Yongjiu

    2016-03-01

    Parameter specification is an important source of uncertainty in large, complex geophysical models. These models generally have multiple model outputs that require multiobjective optimization algorithms. Although such algorithms have long been available, they usually require a large number of model runs and are therefore computationally expensive for large, complex dynamic models. In this paper, a multiobjective adaptive surrogate modeling-based optimization (MO-ASMO) algorithm is introduced that aims to reduce computational cost while maintaining optimization effectiveness. Geophysical dynamic models usually have a prior parameterization scheme derived from the physical processes involved, and our goal is to improve all of the objectives by parameter calibration. In this study, we developed a method for directing the search processes toward the region that can improve all of the objectives simultaneously. We tested the MO-ASMO algorithm against NSGA-II and SUMO with 13 test functions and a land surface model - the Common Land Model (CoLM). The results demonstrated the effectiveness and efficiency of MO-ASMO.

  15. The Efficacy of Galaxy Shape Parameters in Photometric Redshift Estimation: A Neural Network Approach

    SciTech Connect

    Singal, J.; Shmakova, M.; Gerke, B.; Griffith, R.L.; Lotz, J.; /NOAO, Tucson

    2011-05-20

    We present a determination of the effects of including galaxy morphological parameters in photometric redshift estimation with an artificial neural network method. Neural networks, which recognize patterns in the information content of data in an unbiased way, can be a useful estimator of the additional information contained in extra parameters, such as those describing morphology, if the input data are treated on an equal footing. We show that certain principal components of the morphology information are correlated with galaxy type. However, we find that for the data used the inclusion of morphological information does not have a statistically significant benefit for photometric redshift estimation with the techniques employed here. The inclusion of these parameters may result in a trade-off between extra information and additional noise, with the additional noise becoming more dominant as more parameters are added.

  16. Selective Bottlenecks Shape Evolutionary Pathways Taken during Mammalian Adaptation of a 1918-like Avian Influenza Virus.

    PubMed

    Moncla, Louise H; Zhong, Gongxun; Nelson, Chase W; Dinis, Jorge M; Mutschler, James; Hughes, Austin L; Watanabe, Tokiko; Kawaoka, Yoshihiro; Friedrich, Thomas C

    2016-02-10

    Avian influenza virus reassortants resembling the 1918 human pandemic virus can become transmissible among mammals by acquiring mutations in hemagglutinin (HA) and polymerase. Using the ferret model, we trace the evolutionary pathway by which an avian-like virus evolves the capacity for mammalian replication and airborne transmission. During initial infection, within-host HA diversity increased drastically. Then, airborne transmission fixed two polymerase mutations that do not confer a detectable replication advantage. In later transmissions, selection fixed advantageous HA1 variants. Transmission initially involved a "loose" bottleneck, which became strongly selective after additional HA mutations emerged. The stringency and evolutionary forces governing between-host bottlenecks may therefore change throughout host adaptation. Mutations occurred in multiple combinations in transmitted viruses, suggesting that mammalian transmissibility can evolve through multiple genetic pathways despite phenotypic constraints. Our data provide a glimpse into avian influenza virus adaptation in mammals, with broad implications for surveillance on potentially zoonotic viruses. PMID:26867176

  17. Bulimic symptomatology: the role of adaptive perfectionism, shape and weight concern, and self-esteem.

    PubMed

    Watson, Hunna J; Steele, Anna L; Bergin, Jacqueline L; Fursland, Anthea; Wade, Tracey D

    2011-09-01

    An interactive model implicating high perfectionism, high weight and shape concern, and low self-esteem in the onset and maintenance of bulimic symptoms (Bardone, Vohs, Abramson, Heatherton, & Joiner, 2000; Vohs, Bardone, Joiner, Abramson, & Heatherton, 1999) has received mixed support. This study aimed to replicate the cross-sectional model in a clinical sample of women with eating disorders, and to investigate whether the model could predict changes in binge eating and purging at the end of treatment. Eating disorder outpatients (n=353) completed measures of perfectionism, weight/shape concern, self-esteem, and bulimic symptoms at pre-treatment and discharge. Contrary to the hypotheses, the three-way interaction did not predict binge eating or purging cross-sectionally or prospectively as a moderator of psychotherapy outcome. It was concluded that the robustness of the interactive model seems questionable and may be impacted by an inadequate conceptualization of the perfectionism construct. PMID:21704980

  18. Quasi-static shape estimation and control of adaptive truss structures

    NASA Technical Reports Server (NTRS)

    Kuwao, Fumihiro; Chen, Gun-Shing; Wada, Ben K.

    1991-01-01

    Methods for estimating the deformation of adaptive truss structures are proposed which employ internal displacement sensors to measure changes in the length of selected truss members. Based on the measured data from the instrumented truss member, the total truss deformation pattern can be estimated through direct interpolation. To verify the validity of the methods presented here, numerical simulations are carried out for simple plane trusses, a beam truss, and a tetrahedral truss.

  19. Mutation of a Cuticular Protein, BmorCPR2, Alters Larval Body Shape and Adaptability in Silkworm, Bombyx mori

    PubMed Central

    Qiao, Liang; Xiong, Gao; Wang, Ri-xin; He, Song-zhen; Chen, Jie; Tong, Xiao-ling; Hu, Hai; Li, Chun-lin; Gai, Ting-ting; Xin, Ya-qun; Liu, Xiao-fan; Chen, Bin; Xiang, Zhong-huai; Lu, Cheng; Dai, Fang-yin

    2014-01-01

    Cuticular proteins (CPs) are crucial components of the insect cuticle. Although numerous genes encoding cuticular proteins have been identified in known insect genomes to date, their functions in maintaining insect body shape and adaptability remain largely unknown. In the current study, positional cloning led to the identification of a gene encoding an RR1-type cuticular protein, BmorCPR2, highly expressed in larval chitin-rich tissues and at the mulberry leaf-eating stages, which is responsible for the silkworm stony mutant. In the Dazao-stony strain, the BmorCPR2 allele is a deletion mutation with significantly lower expression, compared to the wild-type Dazao strain. Dysfunctional BmorCPR2 in the stony mutant lost chitin binding ability, leading to reduced chitin content in larval cuticle, limitation of cuticle extension, abatement of cuticle tensile properties, and aberrant ratio between internodes and intersegmental folds. These variations induce a significant decrease in cuticle capacity to hold the growing internal organs in the larval development process, resulting in whole-body stiffness, tightness, and hardness, bulging intersegmental folds, and serious defects in larval adaptability. To our knowledge, this is the first study to report the corresponding phenotype of stony in insects caused by mutation of RR1-type cuticular protein. Our findings collectively shed light on the specific role of cuticular proteins in maintaining normal larval body shape and will aid in the development of pest control strategies for the management of Lepidoptera. PMID:24514903

  20. Mutation of a cuticular protein, BmorCPR2, alters larval body shape and adaptability in silkworm, Bombyx mori.

    PubMed

    Qiao, Liang; Xiong, Gao; Wang, Ri-xin; He, Song-zhen; Chen, Jie; Tong, Xiao-ling; Hu, Hai; Li, Chun-lin; Gai, Ting-ting; Xin, Ya-qun; Liu, Xiao-fan; Chen, Bin; Xiang, Zhong-huai; Lu, Cheng; Dai, Fang-yin

    2014-04-01

    Cuticular proteins (CPs) are crucial components of the insect cuticle. Although numerous genes encoding cuticular proteins have been identified in known insect genomes to date, their functions in maintaining insect body shape and adaptability remain largely unknown. In the current study, positional cloning led to the identification of a gene encoding an RR1-type cuticular protein, BmorCPR2, highly expressed in larval chitin-rich tissues and at the mulberry leaf-eating stages, which is responsible for the silkworm stony mutant. In the Dazao-stony strain, the BmorCPR2 allele is a deletion mutation with significantly lower expression, compared to the wild-type Dazao strain. Dysfunctional BmorCPR2 in the stony mutant lost chitin binding ability, leading to reduced chitin content in larval cuticle, limitation of cuticle extension, abatement of cuticle tensile properties, and aberrant ratio between internodes and intersegmental folds. These variations induce a significant decrease in cuticle capacity to hold the growing internal organs in the larval development process, resulting in whole-body stiffness, tightness, and hardness, bulging intersegmental folds, and serious defects in larval adaptability. To our knowledge, this is the first study to report the corresponding phenotype of stony in insects caused by mutation of RR1-type cuticular protein. Our findings collectively shed light on the specific role of cuticular proteins in maintaining normal larval body shape and will aid in the development of pest control strategies for the management of Lepidoptera. PMID:24514903

  1. Cold adaptation shapes the robustness of metabolic networks in Drosophila melanogaster

    PubMed Central

    Williams, CM; Watanabe, M; Guarracino, MR; Ferraro, MB; Edison, AS; Morgan, TJ; Boroujerdi, AFB; Hahn, DA

    2015-01-01

    When ectotherms are exposed to low temperatures, they enter a cold-induced coma (chill coma) that prevents resource acquisition, mating, oviposition, and escape from predation. There is substantial variation in time taken to recover from chill coma both within and among species, and this variation is correlated with habitat temperatures such that insects from cold environments recover more quickly. This suggests an adaptive response, but the mechanisms underlying variation in recovery times are unknown, making it difficult to decisively test adaptive hypotheses. We use replicated lines of Drosophila melanogaster selected in the laboratory for fast (hardy) or slow (susceptible) chill-coma recovery times to investigate modifications to metabolic profiles associated with cold adaptation. We measured metabolite concentrations of flies before, during, and after cold exposure using NMR spectroscopy to test the hypotheses that hardy flies maintain metabolic homeostasis better during cold exposure and recovery, and that their metabolic networks are more robust to cold-induced perturbations. The metabolites of cold-hardy flies were less cold responsive and their metabolic networks during cold exposure were more robust, supporting our hypotheses. Metabolites involved in membrane lipid synthesis, tryptophan metabolism, oxidative stress, energy balance, and proline metabolism were altered by selection on cold tolerance. We discuss the potential significance of these alterations. PMID:25308124

  2. Parallel implementation of an adaptive and parameter-free N-body integrator

    NASA Astrophysics Data System (ADS)

    Pruett, C. David; Ingham, William H.; Herman, Ralph D.

    2011-05-01

    Previously, Pruett et al. (2003) [3] described an N-body integrator of arbitrarily high order M with an asymptotic operation count of O(MN). The algorithm's structure lends itself readily to data parallelization, which we document and demonstrate here in the integration of point-mass systems subject to Newtonian gravitation. High order is shown to benefit parallel efficiency. The resulting N-body integrator is robust, parameter-free, highly accurate, and adaptive in both time-step and order. Moreover, it exhibits linear speedup on distributed parallel processors, provided that each processor is assigned at least a handful of bodies. Program summaryProgram title: PNB.f90 Catalogue identifier: AEIK_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIK_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3052 No. of bytes in distributed program, including test data, etc.: 68 600 Distribution format: tar.gz Programming language: Fortran 90 and OpenMPI Computer: All shared or distributed memory parallel processors Operating system: Unix/Linux Has the code been vectorized or parallelized?: The code has been parallelized but has not been explicitly vectorized. RAM: Dependent upon N Classification: 4.3, 4.12, 6.5 Nature of problem: High accuracy numerical evaluation of trajectories of N point masses each subject to Newtonian gravitation. Solution method: Parallel and adaptive extrapolation in time via power series of arbitrary degree. Running time: 5.1 s for the demo program supplied with the package.

  3. A Method for Determining If Unequal Shape Parameters are Necessary in a Bivariate Gamma Distribution

    NASA Technical Reports Server (NTRS)

    Tubbs, J. D.

    1983-01-01

    A procedure to aid in the deciding between four and five parameters in a Jensen's type bivariate gamma distribution is presented. It is based upon the CDF of the ratio of correlated gamma distributed variates. The criteria are posed in a test of hypothesis setting and results are presented.

  4. Spectral shape parameters of pure CO2 transitions near 1.6 μm by tunable diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Larcher, G.; Landsheere, X.; Schwell, M.; Tran, H.

    2015-10-01

    Room temperature spectra of four lines of pure CO2 in the 1.6 μm region have been measured in a wide range of pressure using a tunable diode laser spectrometer. The spectra of each line have been adjusted using a multi-spectrum fitting procedure with various line-shape models, including the recently recommended Hartmann-Tran profile (HTP). The results show that the collision-induced velocity changes and the speed-dependence effects are clearly observed. It is also shown that taking into account the correlation between velocity- and internal state-changes is necessary to obtain physically-meaningful line-shape parameters. The latter are reported and discussed.

  5. Field trial of a multi-parameters' monitoring network using FBGs adapted directly in the conventional instruments of dams

    NASA Astrophysics Data System (ADS)

    Rosolem, Joao B.; Hortencio, Claudio A.; Floridia, Claudio; Dini, Danilo C.; Penze, Rivael S.; Aires, Bruno N.; Bassan, Fabio R.; Morbach, Rodrigo A.; da Costa, Eduardo F.; Salgado, Felipe C.; Peres, Rodrigo; Fracarolli, João. Paulo V.; Santana, Marcus Vinícius F.; Gregatti, Augusto Cezar M.; Muniz, Guilherme; Amadeo, Gerson L.; Carvalho, Gilson M.; Pertile, Fernando; Melegari, Luis Fernando P.; Herreros, Heloisa O.; Kurokawa, Marcelo Y.; de Avila, Luis F.

    2016-05-01

    This paper presents the results of a field test of a multi-parameters' monitoring network using FBGs adapted directly in the conventional instruments of two dams which are in full operational capability. We presented the details of the design and tests of the sensor's network, such as, the sensors adaptation, the resolution comparison between the conventional instruments and the FBGs, the network topology, the spectral occupancy distribution considering the parameters optical bandwidth and also the temperature compensation for FBGs, the number of sensors by fiber and the performance of the FBGs sensors compared with the conventional instruments used in the Dams.

  6. Model Reference Adaptive H∞ Control for Distributed Parameter Systems of Hyperbolic Type with Input Nonlinearity by Finite Dimensional Controllers

    NASA Astrophysics Data System (ADS)

    Miyasato, Yoshihiko

    The problem of constructing model reference adaptive H∞ control for distributed parameter systems of hyperbolic type preceded by unknown input nonlinearity such as dead zone or backlash, is considered in this paper. Distributed parameter systems are infinite dimensional processes, but the proposed control scheme is constructed from finite dimensional controllers. An adaptive inverse model is introduced to estimate and compensate the input nonlinearity. The stabilizing control signal is added to regulate the effect of spill-over terms, and it is derived as a solution of certain H∞ control problem where the residual part of the inverse model and the spill-over term are considered as external disturbances to the process.

  7. Eco-physiological adaptation shapes the response of calcifying algae to nutrient limitation

    NASA Astrophysics Data System (ADS)

    Šupraha, Luka; Gerecht, Andrea C.; Probert, Ian; Henderiks, Jorijntje

    2015-11-01

    The steady increase in global ocean temperature will most likely lead to nutrient limitation in the photic zone. This will impact the physiology of marine algae, including the globally important calcifying coccolithophores. Understanding their adaptive patterns is essential for modelling carbon production in a low-nutrient ocean. We investigated the physiology of Helicosphaera carteri, a representative of the abundant but under-investigated flagellated functional group of coccolithophores. Two strains isolated from contrasting nutrient regimes (South Atlantic and Mediterranean Sea) were grown in phosphorus-replete and phosphorus-limited batch cultures. While growing exponentially in a phosphorus-replete medium, the Mediterranean strain exhibited on average 24% lower growth rate, 36% larger coccosphere volume and 21% lower particulate inorganic carbon (PIC) production than the Atlantic strain. Under phosphorus limitation, the same strain was capable of reaching a 2.6 times higher cell density than the Atlantic strain due to lower phosphorus requirements. These results suggest that local physiological adaptation can define the performance of this species under nutrient limitation.

  8. Thermal adaptation and phosphorus shape thermal performance in an assemblage of rainforest ants.

    PubMed

    Kaspari, Michael; Clay, Natalie A; Lucas, Jane; Revzen, Shai; Kay, Adam; Yanoviak, Stephen P

    2016-04-01

    We studied the Thermal Performance Curves (TPCs) of 87 species of rainforest ants and found support for both the Thermal Adaptation and Phosphorus-Tolerance hypotheses. TPCs relate a fitness proxy (here, worker speed) to environmental temperature. Thermal Adaptation posits that thermal generalists (ants with flatter, broader TPCs) are favored in the hotter, more variable tropical canopy compared to the cooler, less variable litter below. As predicted, species nesting in the forest canopy 1) had running speeds less sensitive to temperature; 2) ran over a greater range of temperatures; and 3) ran at lower maximum speeds. Tradeoffs between tolerance and maximum performance are often invoked for constraining the evolution of thermal generalists. There was no evidence that ant species traded off thermal tolerance for maximum speed, however. Phosphorus-Tolerance is a second mechanism for generating ectotherms able to tolerate thermal extremes. It posits that ants active at high temperatures invest in P-rich machinery to buffer their metabolism against thermal extremes. Phosphorus content in ant tissue varied three-fold, and as predicted, temperature sensitivity was lower and thermal range was higher in P-rich species. Combined, we show how the vertical distribution of hot and variable vs. cooler and stable microclimates in a single forest contribute to a diversity of TPCs and suggest that a widely varying P stoichiometry among these ants may drive some of these differences. PMID:27220219

  9. Eco-physiological adaptation shapes the response of calcifying algae to nutrient limitation

    PubMed Central

    Šupraha, Luka; Gerecht, Andrea C.; Probert, Ian; Henderiks, Jorijntje

    2015-01-01

    The steady increase in global ocean temperature will most likely lead to nutrient limitation in the photic zone. This will impact the physiology of marine algae, including the globally important calcifying coccolithophores. Understanding their adaptive patterns is essential for modelling carbon production in a low-nutrient ocean. We investigated the physiology of Helicosphaera carteri, a representative of the abundant but under-investigated flagellated functional group of coccolithophores. Two strains isolated from contrasting nutrient regimes (South Atlantic and Mediterranean Sea) were grown in phosphorus-replete and phosphorus-limited batch cultures. While growing exponentially in a phosphorus-replete medium, the Mediterranean strain exhibited on average 24% lower growth rate, 36% larger coccosphere volume and 21% lower particulate inorganic carbon (PIC) production than the Atlantic strain. Under phosphorus limitation, the same strain was capable of reaching a 2.6 times higher cell density than the Atlantic strain due to lower phosphorus requirements. These results suggest that local physiological adaptation can define the performance of this species under nutrient limitation. PMID:26560531

  10. Body shape changes in the elderly and the influence of density assumptions on segment inertia parameters

    NASA Astrophysics Data System (ADS)

    Jensen, Robert K.; Fletcher, P.; Abraham, C.

    1991-04-01

    The segment mass mass proportions and moments of inertia of a sample of twelve females and seven males with mean ages of 67. 4 and 69. 5 years were estimated using textbook proportions based on cadaver studies. These were then compared with the parameters calculated using a mathematical model the zone method. The methodology of the model was fully evaluated for accuracy and precision and judged to be adequate. The results of the comparisons show that for some segments female parameters are quite different from male parameters and inadequately predicted by the cadaver proportions. The largest discrepancies were for the thigh and the trunk. The cadaver predictions were generally less than satisfactory although the common variance for some segments was moderately high. The use ofnon-linear regression and segment anthropometry was illustrated for the thigh moments of inertia and appears to be appropriate. However the predictions from cadaver data need to be examined fully. These results are dependent on the changes in mass and density distribution which occur with aging and the changes which occur with cadaver samples prior to and following death.

  11. A spiral-shaped harvester with an improved harvesting element and an adaptive storage circuit.

    PubMed

    Hu, Hongping; Xue, Huan; Hu, Yuantai

    2007-06-01

    A piezoelectric energy harvester consists of a spiral-shaped piezoelectric bimorph to transfer mechanical energy into electric energy, an electrochemical battery to store the scavenged electric energy, and a rectifier together with a step-down dc-dc converter to connect the two components as an integrated system. A spiral-shaped harvesting structure is studied in this paper because it is very useful in the microminiaturization of advanced sensing technology. The aim of employing a step-down dc-dc converter in the storage circuit is to match the optimal output voltage of the piezoelectric bimorph with the battery voltage for efficient charging. In order to raise the output power density of a harvesting element, moreover, we apply a synchronized switch harvesting on inductor (SSHI) in parallel with the piezoelectric bimorph to artificially extend the closed-circuit interval of the rectifier. Numerical results show that the introduction of a dc-dc converter in the storage circuit or a SSHI in the harvesting structure can raise the charging efficiency several times higher than a harvester without a dc-dc converter or an SSHI. PMID:17571816

  12. An adaptive explanation for the horse-like shape of seahorses.

    PubMed

    Van Wassenbergh, Sam; Roos, Gert; Ferry, Lara

    2011-01-25

    The body shape of seahorses resembles the head and neck of horses because of their curved trunk, their ventrally bent head and their long snout. Seahorses evolved from ancestral, pipefish-like species, which have a straight body. Here, we use a biomechanical analysis and show that the seahorse's peculiar head, neck and trunk posture allows for the capture of small shrimps at larger distances from the eyes compared with pipefish. The results from the mathematical modelling were confirmed by kinematic data of prey-capturing syngnathids: compared with straight-bodied pipefish, all seahorse species studied consistently show an additional forward-reaching component in the path travelled by the mouth during their strikes at prey. This increased strike distance enlarges the volume of water they can probe for food, which is especially useful for tail-attached, sit-and-wait predators like seahorses. The biomechanics of prey capture thus provides a putative selective advantage that may explain the bending of the trunk into a horse-like shape. PMID:21266964

  13. Inquiry in interaction: How local adaptations of curricula shape classroom communities

    NASA Astrophysics Data System (ADS)

    Enyedy, Noel; Goldberg, Jennifer

    2004-11-01

    In this study, we seek a better understanding of how individuals and their daily interactions shape and reshape social structures that constitute a classroom community. Moreover, we provide insight into how discourse and classroom interactions shape the nature of a learning community, as well as which aspects of the classroom culture may be consequential for learning. The participants in this study include two teachers who are implementing a new environmental science program, Global Learning through Observation to Benefit the Environment (GLOBE), and interacting with 54 children in an urban middle school. Both qualitative and quantitative data are analyzed and presented. To gain a better understanding of the inquiry teaching within classroom communities, we compare and contrast the discourse and interactions of the two teachers during three parallel environmental science lessons. The focus of our analysis includes (1) how the community identifies the object or goal of its activity; and (2) how the rights, rules, and roles for members are established and inhabited in interaction. Quantitative analyses of student pre- and posttests suggest greater learning for students in one classroom over the other, providing support for the influence of the classroom community and interactional choices of the teacher on student learning. Implications of the findings from this study are discussed in the context of curricular design, professional development, and educational reform. ? 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 905-935, 2004.

  14. Spectral line parameters including line shapes in the 2ν3 Q branch of 12CH4

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Boudon, Vincent; Ismail, Syed

    2016-07-01

    In this study, we report the first experimental measurements of spectral line shape parameters (self- and air-broadened Lorentz half-widths, pressure-shifts, and line mixing (via off-diagonal relaxation matrix elements) coefficients and their temperature dependences, where appropriate) for transitions in the 2ν3 Q branch manifolds, Q(11)-Q(1) of methane (12CH4), in the 5996.5-6007-cm-1 region. The analysis included 23 high-resolution, high signal-to-noise laboratory absorption spectra recorded with the Bruker IFS-125HR Fourier transform spectrometer (FTS) at JPL. The experimental data were obtained using 12C-enriched 12CH4 and dilute mixtures of 12CH4 in dry air in the 130-296 K range using a room-temperature long path absorption cell and, two custom-built coolable cells. In the analysis, an interactive multispectrum fitting software was employed where all the 23 spectra (11 self-broadened and 12 air-broadened) were fit simultaneously. By carefully applying reasonable constraints to the parameters for severely blended lines, we were able to determine a self-consistent set of broadening, shift and line mixing (relaxation matrix coefficients) parameters for CH4-CH4 and CH4-air collisions. In the majority of cases, a quadratic speed dependence parameter common for all transitions in each Q(J) manifold was determined. However, temperature dependences of the Q branch line mixing parameter could not be determined from the present data. Since no other experimental line shape measurements have been reported for this Q-branch, the present results are compared to available values in the HITRAN2012 database.

  15. Distributions of spin/shape parameters of asteroid families and targeted photometry by ProjectSoft robotic observatory

    NASA Astrophysics Data System (ADS)

    Broz, Miroslav; Durech, Josef; Hanus, Josef; Lehky, Martin

    2014-11-01

    In our recent work (Hanus et al. 2013) we studied dynamics of asteroid families constrained by the distribution of pole latitudes vs semimajor axis. The model contained the following ingredients: (i) the Yarkovsky semimajor-axis drift, (ii) secular spin evolution due to the YORP effect, (iii) collisional reorientations, (iv) a simple treatment of spin-orbit resonances and (v) of mass shedding.We suggest to use a different complementary approach, based on distribution functions of shape parameters. Based on ~1000 old and new convex-hull shape models, we construct the distributions of suitable quantities (ellipticity, normalized facet areas, etc.) and we discuss differences among asteroid populations. We also check for outlier points which may then serve as a possible identification of (large) interlopers among "real" family members.This has also implications for SPH models of asteroid disruptions which can be possibly further constrained by the shape models of resulting fragments. Up to now, the observed size-frequency distribution and velocity field were used as constraints, sometimes allowing for a removal of interlopers (Michel et al. 2011).We also describe ongoing observations by the ProjectSoft robotic observatory called "Blue Eye 600", which supports our efforts to complete the sample of shapes for a substantial fraction of (large) family members. Dense photometry is targeted in such a way to maximize a possibility to derive a new pole/shape model.Other possible applications of the observatory include: (i) fast resolved observations of fireballs (thanks to a fast-motion capability, up to 90 degrees/second), or (ii) an automatic survey of a particular population of objects (MBAs, NEAs, variable stars, novae etc.)Acknowledgements: This work was supported by the Technology Agency of the Czech Republic (grant no. TA03011171) and Czech Science Foundation (grant no. 13-01308S).

  16. Model parameter estimations from residual gravity anomalies due to simple-shaped sources using Differential Evolution Algorithm

    NASA Astrophysics Data System (ADS)

    Ekinci, Yunus Levent; Balkaya, Çağlayan; Göktürkler, Gökhan; Turan, Seçil

    2016-06-01

    An efficient approach to estimate model parameters from residual gravity data based on differential evolution (DE), a stochastic vector-based metaheuristic algorithm, has been presented. We have showed the applicability and effectiveness of this algorithm on both synthetic and field anomalies. According to our knowledge, this is a first attempt of applying DE for the parameter estimations of residual gravity anomalies due to isolated causative sources embedded in the subsurface. The model parameters dealt with here are the amplitude coefficient (A), the depth and exact origin of causative source (zo and xo, respectively) and the shape factors (q and ƞ). The error energy maps generated for some parameter pairs have successfully revealed the nature of the parameter estimation problem under consideration. Noise-free and noisy synthetic single gravity anomalies have been evaluated with success via DE/best/1/bin, which is a widely used strategy in DE. Additionally some complicated gravity anomalies caused by multiple source bodies have been considered, and the results obtained have showed the efficiency of the algorithm. Then using the strategy applied in synthetic examples some field anomalies observed for various mineral explorations such as a chromite deposit (Camaguey district, Cuba), a manganese deposit (Nagpur, India) and a base metal sulphide deposit (Quebec, Canada) have been considered to estimate the model parameters of the ore bodies. Applications have exhibited that the obtained results such as the depths and shapes of the ore bodies are quite consistent with those published in the literature. Uncertainty in the solutions obtained from DE algorithm has been also investigated by Metropolis-Hastings (M-H) sampling algorithm based on simulated annealing without cooling schedule. Based on the resulting histogram reconstructions of both synthetic and field data examples the algorithm has provided reliable parameter estimations being within the sampling limits of

  17. Insecticide resistance and nutrition interactively shape life-history parameters in German cockroaches.

    PubMed

    Jensen, Kim; Ko, Alexander E; Schal, Coby; Silverman, Jules

    2016-01-01

    Fitness-related costs of evolving insecticide resistance have been reported in a number of insect species, but the interplay between evolutionary adaptation to insecticide pressure and variable environmental conditions has received little attention. We provisioned nymphs from three German cockroach (Blattella germanica L.) populations, which differed in insecticide resistance, with either nutritionally rich or poor (diluted) diet throughout their development. One population was an insecticide-susceptible laboratory strain; the other two populations originated from a field-collected indoxacarb-resistant population, which upon collection was maintained either with or without further selection with indoxacarb. We then measured development time, survival to the adult stage, adult body size, and results of a challenge with indoxacarb. Our results show that indoxacarb resistance and poor nutritional condition increased development time and lowered adult body size, with reinforcing interactions. We also found lower survival to the adult stage in the indoxacarb-selected population, which was exacerbated by poor nutrition. In addition, nutrition imparted a highly significant effect on indoxacarb susceptibility. This study exemplifies how poor nutritional condition can aggravate the life-history costs of resistance and elevate the detrimental effects of insecticide exposure, demonstrating how environmental conditions and resistance may interactively impact individual fitness and insecticide efficacy. PMID:27345220

  18. Insecticide resistance and nutrition interactively shape life-history parameters in German cockroaches

    PubMed Central

    Jensen, Kim; Ko, Alexander E.; Schal, Coby; Silverman, Jules

    2016-01-01

    Fitness-related costs of evolving insecticide resistance have been reported in a number of insect species, but the interplay between evolutionary adaptation to insecticide pressure and variable environmental conditions has received little attention. We provisioned nymphs from three German cockroach (Blattella germanica L.) populations, which differed in insecticide resistance, with either nutritionally rich or poor (diluted) diet throughout their development. One population was an insecticide-susceptible laboratory strain; the other two populations originated from a field-collected indoxacarb-resistant population, which upon collection was maintained either with or without further selection with indoxacarb. We then measured development time, survival to the adult stage, adult body size, and results of a challenge with indoxacarb. Our results show that indoxacarb resistance and poor nutritional condition increased development time and lowered adult body size, with reinforcing interactions. We also found lower survival to the adult stage in the indoxacarb-selected population, which was exacerbated by poor nutrition. In addition, nutrition imparted a highly significant effect on indoxacarb susceptibility. This study exemplifies how poor nutritional condition can aggravate the life-history costs of resistance and elevate the detrimental effects of insecticide exposure, demonstrating how environmental conditions and resistance may interactively impact individual fitness and insecticide efficacy. PMID:27345220

  19. Mandible shape and dwarfism in squirrels (Mammalia, Rodentia): interaction of allometry and adaptation

    NASA Astrophysics Data System (ADS)

    Hautier, Lionel; Fabre, Pierre-Henri; Michaux, Jacques

    2009-06-01

    Squirrels include several independent lineages of dwarf forms distributed into two ecological groups: the dwarf tree and flying squirrels. The mandible of dwarf tree squirrels share a highly reduced coronoid process and a condylar process drawn backwards. Dwarf flying squirrels on the other hand, have an elongated coronoid process and a well-differentiated condylar process. To interpret such a difference, Elliptic Fourier Transform was used to evaluate how mandible shape varies with dwarfism in sciurids. The results obtained show that this clear-cut difference cannot be explained by a simple allometric relationship in relation with size decrease. We concluded that the retention of anteriorly positioned eye sockets, in relation with distance estimation, allowed the conservation of a well-differentiated coronoid process in all flying species, despite the trend towards its reduction observed among sciurids as their size decreases.

  20. Mandible shape and dwarfism in squirrels (Mammalia, Rodentia): interaction of allometry and adaptation.

    PubMed

    Hautier, Lionel; Fabre, Pierre-Henri; Michaux, Jacques

    2009-06-01

    Squirrels include several independent lineages of dwarf forms distributed into two ecological groups: the dwarf tree and flying squirrels. The mandible of dwarf tree squirrels share a highly reduced coronoid process and a condylar process drawn backwards. Dwarf flying squirrels on the other hand, have an elongated coronoid process and a well-differentiated condylar process. To interpret such a difference, Elliptic Fourier Transform was used to evaluate how mandible shape varies with dwarfism in sciurids. The results obtained show that this clear-cut difference cannot be explained by a simple allometric relationship in relation with size decrease. We concluded that the retention of anteriorly positioned eye sockets, in relation with distance estimation, allowed the conservation of a well-differentiated coronoid process in all flying species, despite the trend towards its reduction observed among sciurids as their size decreases. PMID:19288073

  1. Deep-sea pennatulaceans (sea pens) - recent discoveries, morphological adaptations, and responses to benthic oceanographic parameters

    NASA Astrophysics Data System (ADS)

    Williams, G. C.

    2015-12-01

    Pennatulaceans are sessile, benthic marine organisms that are bathymetrically wide-ranging, from the intertidal to approximately 6300 m in depth, and are conspicuous constituents of deep-sea environments. The vast majority of species are adapted for anchoring in soft sediments by the cylindrical peduncle - a muscular hydrostatic skeleton. However, in the past decade a few species ("Rockpens") have been discovered and described that can attach to hard substratum such as exposed rocky outcrops at depths between 669 and 1969 m, by a plunger-like adaptation of the base of the peduncle. Of the thirty-six known genera, eleven (or 30%) have been recorded from depths greater than 1000 m. The pennatulacean depth record holders are an unidentified species of Umbellula from 6260 m in the Peru-Chile Trench and a recently-discovered and described genus and species, Porcupinella profunda, from 5300 m the Porcupine Abyssal Plain of the northeastern Atlantic. A morphologically-differentiated type of polyp (acrozooid) have recently been discovered and described in two genera of shallow-water coral reef sea pens. Acrozooids apparently represent asexual buds and presumably can detach from the adult to start clonal colonies through asexual budding. Acrozooids are to be expected in deep-sea pennatulaceans, but so far have not been observed below 24 m in depth. Morphological responses at depths greater than 1000 m in deep-sea pennatulaceas include: fewer polyps, larger polyps, elongated stalks, and clustering of polyps along the rachis. Responses to deep-ocean physical parameters and anthropogenic changes that could affect the abundance and distribution of deep-sea pennatulaceans include changes in bottom current flow and food availability, changes in seawater temperature and pH, habitat destruction by fish trawling, and sunken refuse pollution. No evidence of the effects of ocean acidification or other effects of anthropogenic climate change in sea pens of the deep-sea has been

  2. Design of an adaptive control for a magnetorheological fluid brake with model parameters depending on temperature and speed

    NASA Astrophysics Data System (ADS)

    Russo, R.; Terzo, M.

    2011-11-01

    This paper describes experimental/theoretical activities carried out on a magnetorheological fluid brake (MRFB) prototype. A device model is derived and a detailed evaluation of the influence of temperature and speed on its parameters is performed. It can be seen that temperature and speed act as modifying inputs for the system model and change the value of some of its parameters. More specifically, time constant and torque/current gain are affected by velocity whereas fluid viscosity is only affected by temperature. The presence of the above modifying input suggests the employment of an adaptive approach for MRFB feedback control based on the torque measurement only. Starting from the proposed model, a model reference adaptive control is designed, ensuring that the tracking error converges to zero as time t \\to \\infty . Simulation activity, carried out on the device validated model, confirms the effectiveness of the proposed adaptive controller.

  3. Variation of Ice Crystal Size, Shape and Asymmetry Parameter in Tops of Convective Storm Systems Observed during SEAC4RS

    NASA Astrophysics Data System (ADS)

    van Diedenhoven, B.; Cairns, B.; Fridlind, A. M.; Ackerman, A. S.

    2014-12-01

    The sizes and shapes of ice particles in tops of convective storms have a significant impact on their radiative properties. Ice crystal sizes and shapes likely vary with altitude, environmental conditions and convective strength, but these relationships are not well characterized. The rich dataset of the NASA SEAC4RS field campaign offers unique perspectives to further identify variations of ice crystal sizes and shapes and their relations to environmental and dynamical conditions. Here we focus on data acquired with the Research Scanning Polarimeter (RSP), which was mounted on the high-altitude ER-2 aircraft during SEAC4RS. RSP's unique multi-angular, multi-wavelength total and polarized reflectance measurements allow retrieval of ice effective radius, the aspect ratio of components of ice crystals, the crystal distortion level and ice asymmetry parameter, as well as cloud optical thickness and cloud top height. Using RSP data, as well as data from the eMAS and CPL sensors and in situ probes, we explore the statistical variation of ice properties retrieved during SEAC4RS in tops of convective systems. The data indicates that, in general, ice crystal populations consistent with plate-like components with aspect ratios near 0.4 are prevalent at cloud tops. The asymmetry parameter is around 0.76-0.8 and generally decreases with increasing cloud top height, mainly because the ice crystal distortion increases with height. Below about 12 km height, the effective radius decreases with increasing altitude, as previously shown for convective clouds using satellite data, but at higher levels the SEAC4RS data indicate a transition to effective radii increasing with cloud top height. Here we explore some possible explanations for this transition, related to its approximate coincidence with the level of minimum stability and the homogeneous freezing level, either of which could affect ice crystal formation and evolution. Additionally, we will demonstrate some of the

  4. The effect of quaternary element on the thermodynamic parameters and structure of CuAlMn shape memory alloys

    NASA Astrophysics Data System (ADS)

    Aksu Canbay, C.; Karagoz, Z.

    2013-10-01

    In this study, the Cu-based shape memory alloys were produced by arc melting. We have investigated the effects of the alloying elements on the characteristic transformation temperatures, enthalpy, entropy values, and the structure of Cu-Al-Mn ternary system. The evolution of the transformation temperatures was studied by the differential scanning calorimetry. The characteristic transformation temperatures can be controlled by the variations in the aluminum and manganese content. Additionally, the effect of magnesium and iron on the transformation temperatures and thermodynamic parameters was investigated in the Cu-Al-Mn ternary system. The addition of the magnesium decreases the characteristic transformation temperatures of the Cu-Al-Mn system, but that of the iron increases. The structural changes of the samples were studied by X-ray diffraction measurements and optical microscope observations. Due to the low solubility of the magnesium, the magnesium addition into the Cu-Al-Mn system forms precipitates in the matrix. It is evaluated that the transformation parameters of the CuAlMn shape memory alloys can be controlled by the change of the alloying elements and the weight percentages of alloying elements.

  5. On the shape of bottle-brush macromolecules: Systematic variation of architectural parameters

    NASA Astrophysics Data System (ADS)

    Rathgeber, Silke; Pakula, Tadeusz; Wilk, Agnieszka; Matyjaszewski, Krzysztof; Beers, Kathryn L.

    2005-03-01

    We measured the form factor of bottle-brush macromolecules under good solvent conditions with small-angle neutron scattering and static light scattering. The systems under investigation are brushes, synthesized via the grafting-from route, built from a poly(alkyl methacrylate) backbone to which poly(n-butyl acrylate) side chains are densely grafted. The aim of our work is to study how the systematic variation of structural parameters such as the side chain length and backbone length change the conformation of the polymer brushes in solution. All spectra can be consistently described by a model, considering the bottle-brush polymers as flexible rods with internal density fluctuations. Parameters discussed are (1) the contour length per main chain monomer lb, (2) the fractal dimension of the side chains Ds, as well as (3) the fractal dimension D, and (4) the Kuhn length λk of the overall brush. lb=0.253±0.008nm is found to be independent of the side chain length and equal to the value found for the bare main chain, indicating a strongly stretched conformation for the backbone due to the presence of the side chains. The fractal dimension of the side chains is determined to be Ds=1.75±0.07 which is very close to the value of 1/0.588≈1.70 expected for a three-dimensional self-avoiding random walk (3D-SAW) under good solvent conditions. On larger length scales the overall brush appears to be a 3D-SAW itself (D=1.64±0.08) with a Kuhn-step length of λk=70±4nm. The value is independent of the side chain length and 46 times larger than the Kuhn length of the bare backbone (λk=1.8±0.2nm). The ratio of Kuhn length to brush diameter λk/d⩾20 determines whether lyotropic behavior can be expected or not. Since longer side chains do not lead to more persistent structures, λk/d decreases from 8 to 4 with increasing side chain length and lyotropic behavior becomes unlikely.

  6. Neutron-proton effective range parameters and zero-energy shape dependence

    NASA Astrophysics Data System (ADS)

    Hackenburg, R. W.

    2006-04-01

    The low-energy np elastic-scattering parameters, including the zero-energy free-proton cross section σ0, are determined with a substantially improved precision over previous values, using available np-scattering data below 3 MeV. The method includes a careful handling of a correlation between the singlet and triplet effective ranges which does not seem to have been previously treated. This correlation is responsible for a large systematic error in the singlet effective range and spoils a model-independent determination of the zero-energy triplet effective range. It is shown that improved cross section measurements between 20 and 600 keV (laboratory neutron energy) are needed to overcome the degrading effect of this correlation. The values obtained for the zero-energy cross section and the scattering lengths and effective ranges for the singlet and triplet are: σ0=20.4278(78) b, at=5.4112(15) fm, as=-23.7148(43) fm, rt=1.7436(19) fm, rs=2.750(18) fm (systematic error: -0.059 fm). The widely used measurement of the zero-energy free-proton elastic cross section from W. Dilg, Phys. Rev. C 11, 103 (1975), appears to be in error.

  7. Acoustic seafloor discrimination with echo shape parameters: A comparison with the ground truth

    NASA Astrophysics Data System (ADS)

    van Walree, Paul A.; Tęgowski, Jaroslaw; Laban, Cees; Simons, Dick G.

    2005-11-01

    Features extracted from echosounder bottom returns are compared with the ground truth in a North Sea survey area. The ground truth consists of 50 grab samples for which the grain size distribution, and the gravel and shell contents were determined. Echo envelopes are analysed for two single-beam echosounders, operated at frequencies of 66 and 150 kHz. It is shown that a set of six energetic, statistical, spectral and fractal parameters carries useful information that can be exploited for seafloor characterization and classification purposes. A quantitative comparison of the individual features with the grab sample mean grain size reveals significant correlations. The echo features are also subjected to a principal component analysis in tandem with a cluster analysis. Four sediment classes with different geo-acoustic properties are examined and compared with the grab samples and existing geological information. A subtle difference between the two sounder frequencies is observed in the rendition of an isolated trench with a soft infill of clay and Holocene channel deposits. The acoustic transition from the valley to neighbouring sand and gravel fields occurs more rapidly at the lower of the two examined frequencies. A direct comparison of the acoustic sediment classes with the ground truth reveals that the main sediment types mud, sand, and gravel are more clearly separated at 150 kHz. The acoustic bottom classification scheme also appears particularly sensitive to the presence of gravel at this sounder frequency.

  8. Right Ventricle Functional Parameters Estimation in Arrhythmogenic Right Ventricular Dysplasia Using a Robust Shape Based Deformable Model

    PubMed Central

    Oghli, Mostafa Ghelich; Dehlaghi, Vahab; Zadeh, Ali Mohammad; Fallahi, Alireza; Pooyan, Mohammad

    2014-01-01

    Assessment of cardiac right-ventricle functions plays an essential role in diagnosis of arrhythmogenic right ventricular dysplasia (ARVD). Among clinical tests, cardiac magnetic resonance imaging (MRI) is now becoming the most valid imaging technique to diagnose ARVD. Fatty infiltration of the right ventricular free wall can be visible on cardiac MRI. Finding right-ventricle functional parameters from cardiac MRI images contains segmentation of right-ventricle in each slice of end diastole and end systole phases of cardiac cycle and calculation of end diastolic and end systolic volume and furthermore other functional parameters. The main problem of this task is the segmentation part. We used a robust method based on deformable model that uses shape information for segmentation of right-ventricle in short axis MRI images. After segmentation of right-ventricle from base to apex in end diastole and end systole phases of cardiac cycle, volume of right-ventricle in these phases calculated and then, ejection fraction calculated. We performed a quantitative evaluation of clinical cardiac parameters derived from the automatic segmentation by comparison against a manual delineation of the ventricles. The manually and automatically determined quantitative clinical parameters were statistically compared by means of linear regression. This fits a line to the data such that the root-mean-square error (RMSE) of the residuals is minimized. The results show low RMSE for Right Ventricle Ejection Fraction and Volume (≤ 0.06 for RV EF, and ≤ 10 mL for RV volume). Evaluation of segmentation results is also done by means of four statistical measures including sensitivity, specificity, similarity index and Jaccard index. The average value of similarity index is 86.87%. The Jaccard index mean value is 83.85% which shows a good accuracy of segmentation. The average of sensitivity is 93.9% and mean value of the specificity is 89.45%. These results show the reliability of proposed

  9. Characterization, adaptive traffic shaping, and multiplexing of real-time MPEG II video

    NASA Astrophysics Data System (ADS)

    Agrawal, Sanjay; Barry, Charles F.; Binnai, Vinay; Kazovsky, Leonid G.

    1997-01-01

    We obtain network traffic model for real-time MPEG-II encoded digital video by analyzing video stream samples from real-time encoders from NUKO Information Systems. MPEG-II sample streams include a resolution intensive movie, City of Joy, an action intensive movie, Aliens, a luminance intensive (black and white) movie, Road To Utopia, and a chrominance intensive (color) movie, Dick Tracy. From our analysis we obtain a heuristic model for the encoded video traffic which uses a 15-stage Markov process to model the I,B,P frame sequences within a group of pictures (GOP). A jointly-correlated Gaussian process is used to model the individual frame sizes. Scene change arrivals are modeled according to a gamma process. Simulations show that our MPEG-II traffic model generates, I,B,P frame sequences and frame sizes that closely match the sample MPEG-II stream traffic characteristics as they relate to latency and buffer occupancy in network queues. To achieve high multiplexing efficiency we propose a traffic shaping scheme which sets preferred 1-frame generation times among a group of encoders so as to minimize the overall variation in total offered traffic while still allowing the individual encoders to react to scene changes. Simulations show that our scheme results in multiplexing gains of up to 10% enabling us to multiplex twenty 6 Mbps MPEG-II video streams instead of 18 streams over an ATM/SONET OC3 link without latency or cell loss penalty. This scheme is due for a patent.

  10. Assessment of optimum threshold and particle shape parameter for the image analysis of aggregate size distribution of concrete sections

    NASA Astrophysics Data System (ADS)

    Ozen, Murat; Guler, Murat

    2014-02-01

    Aggregate gradation is one of the key design parameters affecting the workability and strength properties of concrete mixtures. Estimating aggregate gradation from hardened concrete samples can offer valuable insights into the quality of mixtures in terms of the degree of segregation and the amount of deviation from the specified gradation limits. In this study, a methodology is introduced to determine the particle size distribution of aggregates from 2D cross sectional images of concrete samples. The samples used in the study were fabricated from six mix designs by varying the aggregate gradation, aggregate source and maximum aggregate size with five replicates of each design combination. Each sample was cut into three pieces using a diamond saw and then scanned to obtain the cross sectional images using a desktop flatbed scanner. An algorithm is proposed to determine the optimum threshold for the image analysis of the cross sections. A procedure was also suggested to determine a suitable particle shape parameter to be used in the analysis of aggregate size distribution within each cross section. Results of analyses indicated that the optimum threshold hence the pixel distribution functions may be different even for the cross sections of an identical concrete sample. Besides, the maximum ferret diameter is the most suitable shape parameter to estimate the size distribution of aggregates when computed based on the diagonal sieve opening. The outcome of this study can be of practical value for the practitioners to evaluate concrete in terms of the degree of segregation and the bounds of mixture's gradation achieved during manufacturing.

  11. Adaptation.

    PubMed

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

  12. An adaptive threshold detector and channel parameter estimator for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Arabshahi, P.; Mukai, R.; Yan, T. -Y.

    2001-01-01

    This paper presents a method for optimal adaptive setting of ulse-position-modulation pulse detection thresholds, which minimizes the total probability of error for the dynamically fading optical fee space channel.

  13. Adaptive Q-S (lag, anticipated, and complete) time-varying synchronization and parameters identification of uncertain delayed neural networks

    NASA Astrophysics Data System (ADS)

    Yu, Wenwu; Cao, Jinde

    2006-06-01

    In this paper, a new type of generalized Q-S (lag, anticipated, and complete) time-varying synchronization is defined. Adaptive Q-S (lag, anticipated, and complete) time-varying synchronization and parameters identification of uncertain delayed neural networks have been considered, where the delays are multiple time-varying delays. A novel control method is given by using the Lyapunov functional method. With this new and effective method, parameters identification and Q-S (lag, anticipated, and complete) time-varying synchronization can be achieved simultaneously. Simulation results are given to justify the theoretical analysis in this paper.

  14. Numerical study of the shape parameter dependence of the local radial point interpolation method in linear elasticity

    PubMed Central

    Moussaoui, Ahmed; Bouziane, Touria

    2016-01-01

    The method LRPIM is a Meshless method with properties of simple implementation of the essential boundary conditions and less costly than the moving least squares (MLS) methods. This method is proposed to overcome the singularity associated to polynomial basis by using radial basis functions. In this paper, we will present a study of a 2D problem of an elastic homogenous rectangular plate by using the method LRPIM. Our numerical investigations will concern the influence of different shape parameters on the domain of convergence,accuracy and using the radial basis function of the thin plate spline. It also will presents a comparison between numerical results for different materials and the convergence domain by precising maximum and minimum values as a function of distribution nodes number. The analytical solution of the deflection confirms the numerical results. The essential points in the method are: • The LRPIM is derived from the local weak form of the equilibrium equations for solving a thin elastic plate. • The convergence of the LRPIM method depends on number of parameters derived from local weak form and sub-domains. • The effect of distributions nodes number by varying nature of material and the radial basis function (TPS). PMID:27054093

  15. Numerical study of the shape parameter dependence of the local radial point interpolation method in linear elasticity.

    PubMed

    Moussaoui, Ahmed; Bouziane, Touria

    2016-01-01

    The method LRPIM is a Meshless method with properties of simple implementation of the essential boundary conditions and less costly than the moving least squares (MLS) methods. This method is proposed to overcome the singularity associated to polynomial basis by using radial basis functions. In this paper, we will present a study of a 2D problem of an elastic homogenous rectangular plate by using the method LRPIM. Our numerical investigations will concern the influence of different shape parameters on the domain of convergence,accuracy and using the radial basis function of the thin plate spline. It also will presents a comparison between numerical results for different materials and the convergence domain by precising maximum and minimum values as a function of distribution nodes number. The analytical solution of the deflection confirms the numerical results. The essential points in the method are: •The LRPIM is derived from the local weak form of the equilibrium equations for solving a thin elastic plate.•The convergence of the LRPIM method depends on number of parameters derived from local weak form and sub-domains.•The effect of distributions nodes number by varying nature of material and the radial basis function (TPS). PMID:27054093

  16. A highly shape-adaptive, stretchable design based on conductive liquid for energy harvesting and self-powered biomechanical monitoring

    PubMed Central

    Yi, Fang; Wang, Xiaofeng; Niu, Simiao; Li, Shengming; Yin, Yajiang; Dai, Keren; Zhang, Guangjie; Lin, Long; Wen, Zhen; Guo, Hengyu; Wang, Jie; Yeh, Min-Hsin; Zi, Yunlong; Liao, Qingliang; You, Zheng; Zhang, Yue; Wang, Zhong Lin

    2016-01-01

    The rapid growth of deformable and stretchable electronics calls for a deformable and stretchable power source. We report a scalable approach for energy harvesters and self-powered sensors that can be highly deformable and stretchable. With conductive liquid contained in a polymer cover, a shape-adaptive triboelectric nanogenerator (saTENG) unit can effectively harvest energy in various working modes. The saTENG can maintain its performance under a strain of as large as 300%. The saTENG is so flexible that it can be conformed to any three-dimensional and curvilinear surface. We demonstrate applications of the saTENG as a wearable power source and self-powered sensor to monitor biomechanical motion. A bracelet-like saTENG worn on the wrist can light up more than 80 light-emitting diodes. Owing to the highly scalable manufacturing process, the saTENG can be easily applied for large-area energy harvesting. In addition, the saTENG can be extended to extract energy from mechanical motion using flowing water as the electrode. This approach provides a new prospect for deformable and stretchable power sources, as well as self-powered sensors, and has potential applications in various areas such as robotics, biomechanics, physiology, kinesiology, and entertainment. PMID:27386560

  17. A highly shape-adaptive, stretchable design based on conductive liquid for energy harvesting and self-powered biomechanical monitoring.

    PubMed

    Yi, Fang; Wang, Xiaofeng; Niu, Simiao; Li, Shengming; Yin, Yajiang; Dai, Keren; Zhang, Guangjie; Lin, Long; Wen, Zhen; Guo, Hengyu; Wang, Jie; Yeh, Min-Hsin; Zi, Yunlong; Liao, Qingliang; You, Zheng; Zhang, Yue; Wang, Zhong Lin

    2016-06-01

    The rapid growth of deformable and stretchable electronics calls for a deformable and stretchable power source. We report a scalable approach for energy harvesters and self-powered sensors that can be highly deformable and stretchable. With conductive liquid contained in a polymer cover, a shape-adaptive triboelectric nanogenerator (saTENG) unit can effectively harvest energy in various working modes. The saTENG can maintain its performance under a strain of as large as 300%. The saTENG is so flexible that it can be conformed to any three-dimensional and curvilinear surface. We demonstrate applications of the saTENG as a wearable power source and self-powered sensor to monitor biomechanical motion. A bracelet-like saTENG worn on the wrist can light up more than 80 light-emitting diodes. Owing to the highly scalable manufacturing process, the saTENG can be easily applied for large-area energy harvesting. In addition, the saTENG can be extended to extract energy from mechanical motion using flowing water as the electrode. This approach provides a new prospect for deformable and stretchable power sources, as well as self-powered sensors, and has potential applications in various areas such as robotics, biomechanics, physiology, kinesiology, and entertainment. PMID:27386560

  18. Divergent selection for shape of growth curve in Japanese quail. 1. Responses in growth parameters and food conversion.

    PubMed

    Hyánková, L; Knízetová, H; Dĕdková, L; Hort, J

    2001-12-01

    1. HG and LG quail lines selected for high and low relative weight gain between 11 and 28 d of age (RG11-28), respectively, and an unselected C line were compared. Mature body weight of both selected lines was held at that of the C line. Progeny of generation 6 were used for analysis. 2. Divergent selection for RG11-28 brought about opposite changes in the growth rates shortly after hatching. 3. Parameters of the Richards function were used to describe the growth curve. The largest differences between HG and LG lines occurred in age (t+) and body weight (y+) at the inflection point of the growth curve (on average for both sexes 28% and 20%, respectively). For HG quail, the parameter t+ was 5 d later than that for LG quail (18.6 vs 14.1 d for males and 20.6 vs 15.6 d for females, respectively), and consequently the parameter y+ was greater (90.3 vs 84.0 g for males and 104.5 vs 96.1 g for females, respectively). The shape of the growth curve expressed by the y+/A ratio was substantialy different for HG and LG quail (44.8% vs 39.6% for males and 43.5% vs 36.8% for females, respectively). 4. The food/gain ratios for the fattening period (3 to 35 d of age) were 3.21, 3.47 and 3.34 for the HG, LG and C lines, respectively. The HG quail started to utilise food more efficiently than the LG quail as early as 10 to 14 d, that is, at the age when their relative growth rate first became greater. 5. The relative deviations of the HG and LG lines from the C line are discussed. PMID:11811909

  19. Transient analysis of an adaptive system for optimization of design parameters

    NASA Technical Reports Server (NTRS)

    Bayard, D. S.

    1992-01-01

    Averaging methods are applied to analyzing and optimizing the transient response associated with the direct adaptive control of an oscillatory second-order minimum-phase system. The analytical design methods developed for a second-order plant can be applied with some approximation to a MIMO flexible structure having a single dominant mode.

  20. The Use of Unidimensional Item Parameter Estimates of Multidimensional Items in Adaptive Testing.

    ERIC Educational Resources Information Center

    Ackerman, Terry A.

    The purpose of this study was to investigate the effect of using multidimensional items in a computer adaptive test (CAT) setting which assumes a unidimensional item response theory (IRT) framework. Previous research has suggested that the composite of multidimensional abilities being estimated by a unidimensional IRT model is not constant…

  1. [Correction of autonomic reactions parameters in organism of cosmonaut with adaptive biocontrol method

    NASA Technical Reports Server (NTRS)

    Kornilova, L. N.; Cowings, P. S.; Toscano, W. B.; Arlashchenko, N. I.; Korneev, D. Iu; Ponomarenko, A. V.; Salagovich, S. V.; Sarantseva, A. V.; Kozlovskaia, I. B.

    2000-01-01

    Presented are results of testing the method of adaptive biocontrol during preflight training of cosmonauts. Within the MIR-25 crew, a high level of controllability of the autonomous reactions was characteristic of Flight Commanders MIR-23 and MIR-25 and flight Engineer MIR-23, while Flight Engineer MIR-25 displayed a weak intricate dependence of these reactions on the depth of relaxation or strain.

  2. Simulated lumped-parameter system reduced-order adaptive control studies

    NASA Technical Reports Server (NTRS)

    Johnson, C. R., Jr.; Lawrence, D. A.; Taylor, T.; Malakooti, M. V.

    1981-01-01

    Two methods of interpreting the misbehavior of reduced order adaptive controllers are discussed. The first method is based on system input-output description and the second is based on state variable description. The implementation of the single input, single output, autoregressive, moving average system is considered.

  3. Adapt

    NASA Astrophysics Data System (ADS)

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

  4. Line-Parameter Measurements and Stringent Tests of Line-Shape Models Based on Cavity-Enhanced Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Bielska, Katarzyna; Fleisher, Adam J.; Hodges, Joseph T.; Lin, Hong; Long, David A.; Reed, Zachary D.; Sironneau, Vincent; Truong, Gar-Wing; Wójtewicz, Szymon

    2014-06-01

    Laser methods that are based on cavity-enhanced absorption spectroscopy (CEAS) are well-suited for measuring molecular line parameters under conditions of low optical density, and as such they are complementary to broadband Fourier-transform spectroscopy (FTS) techniques. Attributes of CEAS include relatively low detection limits, accurate and precise detuning axes and high fidelity measurements of line shape. In many cases these performance criteria are superior to those obtained using direct laser absorption spectroscopy and FTS-based systems. In this presentation we will survey several examples of frequency-stabilized cavity ring-down spectroscopy (FS-CRDS)1 measurements obtained with laser spectrometers developed at the National Institute of Standards and Technology (NIST) in Gaithersburg Maryland. These experiments, which are motivated by atmospheric monitoring and remote-sensing applications that require high-precision and accuracy, involve nearinfrared transitions of carbon dioxide, water, oxygen and methane. We discuss spectra with signal-to-noise ratios exceeding 106, frequency axes with absolute uncertainties in the 10 kHz to 100 kHz range and linked to a Cs clock, line parameters with relative uncertainties at the 0.2 % level and isotopic ratios measured with a precision of 0.03 %. We also present FS-CRDS measurements of CO2 line intensities which are measured at atmospheric concentration levels and linked to gravimetric standards for CO2 in air, and we quantify pressure-dependent deviations between various theoretical line profiles and measured line shapes. Finally we also present recent efforts to increase data throughput and spectral coverage in CEAS experiments. We describe three new high-bandwidth CEAS techniques including frequency-agile, rapid scanning spectroscopy (FARS)2, which enables continuous-wave measurements of cavity mode linewidth and acquisition of ringdown decays with no dead time during laser frequency tuning, heterodyne

  5. Dynamics of some parameters of the endocrine and lymphatic systems in rats during cold adaptation

    SciTech Connect

    Borodin, Yu.I.; Sedova, L.A.; Selyatitskaya, V.G.; Shorin, Yu.P.

    1986-02-01

    This paper examines the combined behavior of the endocrine and lymphatic systems in rats at stages of long-term adaptation of the animals to moderate cold. After decapitation of male Wister rats, the corticosterone concentration in the blood plasma was determined by saturation analysis and serum levels of thyroxine (T/sub 4/) and triiodothyronine (T/sub 3/) were determined by radioimmunoassay. The thymus was weighed and the structure of the popliteal lymph nodes (LN) was studied in histological sections stained with hematoxylin and eosin and with azure II-eosin. Morphometry of the structural components of LN was undertaken and the numbers of the various cell forms per 1000 cells were counted in different zones of LN. The increase in activity of the lymphoid tissue in the phase of adaptation may be connected with intensification of the peripheral action of thyroid hormones. During long-term adaptation, in the phase of consistently increased specific resistance, a new type of endocrine-lymphoid relation is formed, and it differs significantly both in the original state and in the acute phase of stress.

  6. Dynamics and adaptive control of a dual-arm space robot with closed-loop constraints and uncertain inertial parameters

    NASA Astrophysics Data System (ADS)

    Jia, Ying-Hong; Hu, Quan; Xu, Shi-Jie

    2014-02-01

    A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of controlling the position and attitude of both the satellite base and the payload grasped by the manipulator end effectors. The equations of motion in reduced-order form for the constrained system are derived by incorporating the constraint equations in terms of accelerations into Kane's equations of the unconstrained system. Model analysis shows that the resulting equations perfectly meet the requirement of adaptive controller design. Consequently, by using an indirect approach, an adaptive control scheme is proposed to accomplish position/attitude trajectory tracking control with the uncertain parameters being estimated on-line. The actuator redundancy due to the closed-loop constraints is utilized to minimize a weighted norm of the joint torques. Global asymptotic stability is proven by using Lyapunov's method, and simulation results are also presented to demonstrate the effectiveness of the proposed approach. [Figure not available: see fulltext.

  7. Model parameter adaption-based multi-model algorithm for extended object tracking using a random matrix.

    PubMed

    Li, Borui; Mu, Chundi; Han, Shuli; Bai, Tianming

    2014-01-01

    Traditional object tracking technology usually regards the target as a point source object. However, this approximation is no longer appropriate for tracking extended objects such as large targets and closely spaced group objects. Bayesian extended object tracking (EOT) using a random symmetrical positive definite (SPD) matrix is a very effective method to jointly estimate the kinematic state and physical extension of the target. The key issue in the application of this random matrix-based EOT approach is to model the physical extension and measurement noise accurately. Model parameter adaptive approaches for both extension dynamic and measurement noise are proposed in this study based on the properties of the SPD matrix to improve the performance of extension estimation. An interacting multi-model algorithm based on model parameter adaptive filter using random matrix is also presented. Simulation results demonstrate the effectiveness of the proposed adaptive approaches and multi-model algorithm. The estimation performance of physical extension is better than the other algorithms, especially when the target maneuvers. The kinematic state estimation error is lower than the others as well. PMID:24763252

  8. Parameters influencing the fatigue life of a Cu-Al-Be single-crystal shape memory alloy under repeated bending

    NASA Astrophysics Data System (ADS)

    Siredey-Schwaller, N.; Eberhardt, A.; Bastie, P.

    2009-02-01

    One of the principal limitations in the use of shape memory alloys is certainly fatigue behaviour. Initially, the mechanical behaviour of polycrystals evolves during cycling and then rupture occurs after a relatively small number of cycles, in particular for deformation higher than a few per cent. If one replaces the polycrystal by a single crystal, one notices an important increase in the fatigue lifespan, mainly for high deformation (Siredey et al 2005 Mater. Sci. Eng. A 396 296-301). The aim of this study is to analyse the role of three parameters influencing the lifespan in mechanical fatigue. The first one relates to the atmosphere in which the test is carried out. No notable influence was found. However, for samples having spent 44 000 h in air, one notes a lifespan reduction for those tested in the presence of air, whereas it is normal for those tested under argon. In the second part, the effect of the surface state will be discussed. As already presented in Siredey et al (2005 Mater. Sci. Eng. A 396 296-301), surface roughness influences lifespan, especially for low imposed strain. However, for higher strain this effect is much less important. On the surface, striations due to martensitic transformations appear during cycling. However, the damage inside these striations seems not to be correlated to rupture. The third parameter relates to crystalline quality of the single crystal. It was studied with a hard x-ray diffractometer using a transposition at high energy of the Guinier-Tennevin method. Crystalline quality is found to play a crucial role in the lifespan in fatigue. The presence of sub-grains disoriented by about 1° and mosaicity can reduce the lifespan by a factor up to 10.

  9. Adaptation of facial synthesis to parameter analysis in MPEG-4 visual communication

    NASA Astrophysics Data System (ADS)

    Yu, Lu; Zhang, Jingyu; Liu, Yunhai

    2000-12-01

    In MPEG-4, Facial Definition Parameters (FDPs) and Facial Animation Parameters (FAPs) are defined to animate 1 a facial object. Most of the previous facial animation reconstruction systems were focused on synthesizing animation from manually or automatically generated FAPs but not the FAPs extracted from natural video scene. In this paper, an analysis-synthesis MPEG-4 visual communication system is established, in which facial animation is reconstructed from FAPs extracted from natural video scene.

  10. Conditions that influence the accuracy of anthropometric parameter estimation for human body segments using shape-from-silhouette

    NASA Astrophysics Data System (ADS)

    Mundermann, Lars; Mundermann, Annegret; Chaudhari, Ajit M.; Andriacchi, Thomas P.

    2005-01-01

    Anthropometric parameters are fundamental for a wide variety of applications in biomechanics, anthropology, medicine and sports. Recent technological advancements provide methods for constructing 3D surfaces directly. Of these new technologies, visual hull construction may be the most cost-effective yet sufficiently accurate method. However, the conditions influencing the accuracy of anthropometric measurements based on visual hull reconstruction are unknown. The purpose of this study was to evaluate the conditions that influence the accuracy of 3D shape-from-silhouette reconstruction of body segments dependent on number of cameras, camera resolution and object contours. The results demonstrate that the visual hulls lacked accuracy in concave regions and narrow spaces, but setups with a high number of cameras reconstructed a human form with an average accuracy of 1.0 mm. In general, setups with less than 8 cameras yielded largely inaccurate visual hull constructions, while setups with 16 and more cameras provided good volume estimations. Body segment volumes were obtained with an average error of 10% at a 640x480 resolution using 8 cameras. Changes in resolution did not significantly affect the average error. However, substantial decreases in error were observed with increasing number of cameras (33.3% using 4 cameras; 10.5% using 8 cameras; 4.1% using 16 cameras; 1.2% using 64 cameras).

  11. Conditions that influence the accuracy of anthropometric parameter estimation for human body segments using shape-from-silhouette

    NASA Astrophysics Data System (ADS)

    Mündermann, Lars; Mündermann, Annegret; Chaudhari, Ajit M.; Andriacchi, Thomas P.

    2004-12-01

    Anthropometric parameters are fundamental for a wide variety of applications in biomechanics, anthropology, medicine and sports. Recent technological advancements provide methods for constructing 3D surfaces directly. Of these new technologies, visual hull construction may be the most cost-effective yet sufficiently accurate method. However, the conditions influencing the accuracy of anthropometric measurements based on visual hull reconstruction are unknown. The purpose of this study was to evaluate the conditions that influence the accuracy of 3D shape-from-silhouette reconstruction of body segments dependent on number of cameras, camera resolution and object contours. The results demonstrate that the visual hulls lacked accuracy in concave regions and narrow spaces, but setups with a high number of cameras reconstructed a human form with an average accuracy of 1.0 mm. In general, setups with less than 8 cameras yielded largely inaccurate visual hull constructions, while setups with 16 and more cameras provided good volume estimations. Body segment volumes were obtained with an average error of 10% at a 640x480 resolution using 8 cameras. Changes in resolution did not significantly affect the average error. However, substantial decreases in error were observed with increasing number of cameras (33.3% using 4 cameras; 10.5% using 8 cameras; 4.1% using 16 cameras; 1.2% using 64 cameras).

  12. Self- and Air-Broadened Line Shape Parameters of (12)CH(4) : 4500-4620 cm(-1)

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, K.; Brown, L. R.; Crawford, T. J.; Smith, M. A. H.; Mantz, A. W.; Predoi-Cross, A.

    2014-06-01

    Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. We report the self and air-broadened Lorentz widths, shifts and line mixing coefficients along with their temperature dependencies for methane absorption lines in the 2.2 µm spectral region. For this, we obtained a series of high-resolution, high S/N spectra of 99.99% 12C-enriched samples of pure methane and its dilute mixtures in dry air at cold temperatures down to 150 K using the Bruker IFS 125HR Fourier transform spectrometer at JPL. The coolable absorption cell had an optical path of 20.38 cm and was specially built to reside inside the sample compartment of the Bruker FTS1. The 13 spectra used in the analysis consisted of seven pure 12CH4 spectra at pressures from 4.5 to 169 Torr and six air-broadened spectra with total sample pressures of 113-300 Torr and methane volume mixing ratios between 4 and 9.7%. These 13 spectra were fit simultaneously using the multispectrum least-squares fitting technique2. The results will be compared to existing values reported in the literature3. as part of the GNU EPrints system , and is freely redistributable under the GPL .

  13. [Dynamics of parameters of energy metabolism at adaptation to diving in human].

    PubMed

    Baranova, T I; Kovalenko, R I; Mitrofanova, A V; Ianvareva, I N

    2010-01-01

    Studies of the diving reaction in the comparative-evolutionary aspect have shown that a complex of reactions providing the oxygen-saving effect during diving is inherent in human like in the secondary-aquatic mammals. This is confirmed by results of study of peculiarities of energy metabolism during imitation of diving (hold-up of respiration with immersion of face into the cold water--the cold-hypoxic-hypercapnic action) (CHHA). Data of gas analysis have shown that during the diving imitation the oxygen consumption rate is statistically significantly lower than during the usual hold-up of respiration (Genche's test). As shown by the study, this is due to the greater degree to vasoconstriction of peripheral vessels and selective redistribution of blood flow than to slowing down of the blood flow caused by reflex bradycardia during diving. It has been revealed that under effect of adaptation to CHHA, on the background of a decrease of the total energy consumption by the organism there occurs some increase of contribution of aerobic processes to its energy provision. Adaptation to CHHA has been shown to be accompanied by a decrease of reactivity of the parasympathetic chain of regulation of the heart chronotropic function and by an increase of duration of apnea. The duration of apnea is directly correlated with level of insulin--the hormone stimulating the anaerobic pathway of energy provision. Under effect of adaptation to CHHA there has been established an increase of the organism resistance to stress actions, which is confirmed by the lower levels of cortisol and thyroid hormones in representatives of the experimental group as compared with the control one. PMID:21061652

  14. New parameters in adaptive testing of ferromagnetic materials utilizing magnetic Barkhausen noise

    NASA Astrophysics Data System (ADS)

    Pal'a, Jozef; Ušák, Elemír

    2016-03-01

    A new method of magnetic Barkhausen noise (MBN) measurement and optimization of the measured data processing with respect to non-destructive evaluation of ferromagnetic materials was tested. Using this method we tried to found, if it is possible to enhance sensitivity and stability of measurement results by replacing the traditional MBN parameter (root mean square) with some new parameter. In the tested method, a complex set of the MBN from minor hysteresis loops is measured. Afterward, the MBN data are collected into suitably designed matrices and optimal parameters of MBN with respect to maximum sensitivity to the evaluated variable are searched. The method was verified on plastically deformed steel samples. It was shown that the proposed measuring method and measured data processing bring an improvement of the sensitivity to the evaluated variable when comparing with measuring traditional MBN parameter. Moreover, we found a parameter of MBN, which is highly resistant to the changes of applied field amplitude and at the same time it is noticeably more sensitive to the evaluated variable.

  15. Scale parameter-estimating method for adaptive fingerprint pore extraction model

    NASA Astrophysics Data System (ADS)

    Yi, Yao; Cao, Liangcai; Guo, Wei; Luo, Yaping; He, Qingsheng; Jin, Guofan

    2011-11-01

    Sweat pores and other level 3 features have been proven to provide more discriminatory information about fingerprint characteristics, which is useful for personal identification especially in law enforcement applications. With the advent of high resolution (>=1000 ppi) fingerprint scanning equipment, sweat pores are attracting increasing attention in automatic fingerprint identification system (AFIS), where the extraction of pores is a critical step. This paper presents a scale parameter-estimating method in filtering-based pore extraction procedure. Pores are manually extracted from a 1000 ppi grey-level fingerprint image. The size and orientation of each detected pore are extracted together with local ridge width and orientation. The quantitative relation between the pore parameters (size and orientation) and local image parameters (ridge width and orientation) is statistically obtained. The pores are extracted by filtering fingerprint image with the new pore model, whose parameters are determined by local image parameters and the statistically established relation. Experiments conducted on high resolution fingerprints indicate that the new pore model gives good performance in pore extraction.

  16. Polyhedral shape model for terrain correction of gravity and gravity gradient data based on an adaptive mesh

    NASA Astrophysics Data System (ADS)

    Guo, Zhikui; Chen, Chao; Tao, Chunhui

    2016-04-01

    tests and field applications indicate that the adaptive terrain correction method can be adopted as a rapid and accurate tool of marine gravity data processing. References Davis, K. &Kass, M.A. & Li, Y., 2011. Rapid gravity and gravity gradiometry terrain corrections via an adaptive quadtree mesh discretization, EXPLOR GEOPHYS, 42, 88-97. Sandwell, D.T., Müller, R.D., Smith, W.H., Garcia, E. & Francis, R., 2014. New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure, SCIENCE, 346, 65-67. Tao, C., Li, H., Jin, X., Zhou, J., Wu, T., He, Y., Deng, X., Gu, C., Zhang, G. & Liu, W., 2014. Seafloor hydrothermal activity and polymetallic sulfide exploration on the southwest Indian ridge, CHINESE SCI BULL, 59, 2266-2276. Tsoulis, D., 2012. Analytical computation of the full gravity tensor of a homogeneous arbitrarily shaped polyhedral source using line integrals, GEOPHYSICS, 77, F1-F11.

  17. Adaptive approximation method for joint parameter estimation and identical synchronization of chaotic systems.

    PubMed

    Mariño, Inés P; Míguez, Joaquín

    2005-11-01

    We introduce a numerical approximation method for estimating an unknown parameter of a (primary) chaotic system which is partially observed through a scalar time series. Specifically, we show that the recursive minimization of a suitably designed cost function that involves the dynamic state of a fully observed (secondary) system and the observed time series can lead to the identical synchronization of the two systems and the accurate estimation of the unknown parameter. The salient feature of the proposed technique is that the only external input to the secondary system is the unknown parameter which needs to be adjusted. We present numerical examples for the Lorenz system which show how our algorithm can be considerably faster than some previously proposed methods. PMID:16383795

  18. Shaping ability of Reciproc and TF Adaptive systems in severely curved canals of rapid microCT-based prototyping molar replicas

    PubMed Central

    ORDINOLA-ZAPATA, Ronald; BRAMANTE, Clovis Monteiro; DUARTE, Marco Antonio Húngaro; CAVENAGO, Bruno Cavalini; JARAMILLO, David; VERSIANI, Marco Aurélio

    2014-01-01

    Objective: To evaluate the shaping ability of Reciproc and Twisted-File Adaptive systems in rapid prototyping replicas. Material and Methods: Two mandibular molars showing S-shaped and 62-degree curvatures in the mesial root were scanned by using a microcomputed tomography (μCT) system. The data were exported in the stereolitograhic format and 20 samples of each molar were printed at 16 µm resolution. The mesial canals of 10 replicas of each specimen were prepared with each system. Transportation was measured by overlapping radiographs taken before and after preparation and resin thickness after instrumentation was measured by μCT. Results: Both systems maintained the original shape of the apical third in both anatomies (P>0.05). Overall, considering the resin thickness in the 62-degree replicas, no statistical difference was found between the systems (P>0.05). In the S-shaped curvature replica, Reciproc significantly decreased the thickness of the resin walls in comparison with TF Adaptive. Conclusions: The evaluated systems were able to maintain the original shape at the apical third of severely curved mesial canals of molar replicas. PMID:24918662

  19. An adaptive procedure for the numerical parameters of a particle simulation

    NASA Astrophysics Data System (ADS)

    Galitzine, Cyril; Boyd, Iain D.

    2015-01-01

    In this article, a computational procedure that automatically determines the optimum time step, cell weight and species weights for steady-state multi-species DSMC (direct simulation Monte Carlo) simulations is presented. The time step is required to satisfy the basic requirements of the DSMC method while the weight and relative weights fields are chosen so as to obtain a user-specified average number of particles in all cells of the domain. The procedure allows the conduct of efficient DSMC simulations with minimal user input and is integrable into existing DSMC codes. The adaptive method is used to simulate a test case consisting of two counterflowing jets at a Knudsen number of 0.015. Large accuracy gains for sampled number densities and velocities over a standard simulation approach for the same number of particles are observed.

  20. Multi-parameter battery state estimator based on the adaptive and direct solution of the governing differential equations

    NASA Astrophysics Data System (ADS)

    Wang, Shuoqin; Verbrugge, Mark; Wang, John S.; Liu, Ping

    2011-10-01

    We report the development of an adaptive, multi-parameter battery state estimator based on the direct solution of the differential equations that govern an equivalent circuit representation of the battery. The core of the estimator includes two sets of inter-related equations corresponding to discharge and charge events respectively. Simulation results indicate that the estimator gives accurate prediction and numerically stable performance in the regression of model parameters. The estimator is implemented in a vehicle-simulated environment to predict the state of charge (SOC) and the charge and discharge power capabilities (state of power, SOP) of a lithium ion battery. Predictions for the SOC and SOP agree well with experimental measurements, demonstrating the estimator's application in battery management systems. In particular, this new approach appears to be very stable for high-frequency data streams.

  1. Artificial immune system based on adaptive clonal selection for feature selection and parameters optimisation of support vector machines

    NASA Astrophysics Data System (ADS)

    Sadat Hashemipour, Maryam; Soleimani, Seyed Ali

    2016-01-01

    Artificial immune system (AIS) algorithm based on clonal selection method can be defined as a soft computing method inspired by theoretical immune system in order to solve science and engineering problems. Support vector machine (SVM) is a popular pattern classification method with many diverse applications. Kernel parameter setting in the SVM training procedure along with the feature selection significantly impacts on the classification accuracy rate. In this study, AIS based on Adaptive Clonal Selection (AISACS) algorithm has been used to optimise the SVM parameters and feature subset selection without degrading the SVM classification accuracy. Several public datasets of University of California Irvine machine learning (UCI) repository are employed to calculate the classification accuracy rate in order to evaluate the AISACS approach then it was compared with grid search algorithm and Genetic Algorithm (GA) approach. The experimental results show that the feature reduction rate and running time of the AISACS approach are better than the GA approach.

  2. Adaptation of a polyphagous herbivore to a novel host plant extensively shapes the transcriptome of herbivore and host.

    PubMed

    Wybouw, Nicky; Zhurov, Vladimir; Martel, Catherine; Bruinsma, Kristie A; Hendrickx, Frederik; Grbić, Vojislava; Van Leeuwen, Thomas

    2015-09-01

    Generalist arthropod herbivores rapidly adapt to a broad range of host plants. However, the extent of transcriptional reprogramming in the herbivore and its hosts associated with adaptation remains poorly understood. Using the spider mite Tetranychus urticae and tomato as models with available genomic resources, we investigated the reciprocal genomewide transcriptional changes in both spider mite and tomato as a consequence of mite's adaptation to tomato. We transferred a genetically diverse mite population from bean to tomato where triplicated populations were allowed to propagate for 30 generations. Evolving populations greatly increased their reproductive performance on tomato relative to their progenitors when reared under identical conditions, indicative of genetic adaptation. Analysis of transcriptional changes associated with mite adaptation to tomato revealed two main components. First, adaptation resulted in a set of mite genes that were constitutively downregulated, independently of the host. These genes were mostly of an unknown function. Second, adapted mites mounted an altered transcriptional response that had greater amplitude of changes when re-exposed to tomato, relative to nonadapted mites. This gene set was enriched in genes encoding detoxifying enzymes and xenobiotic transporters. Besides the direct effects on mite gene expression, adaptation also indirectly affected the tomato transcriptional responses, which were attenuated upon feeding of adapted mites, relative to the induced responses by nonadapted mite feeding. Thus, constitutive downregulation and increased transcriptional plasticity of genes in a herbivore may play a central role in adaptation to host plants, leading to both a higher detoxification potential and reduced production of plant defence compounds. PMID:26211543

  3. Mechanically adaptive and shape-memory behaviour of chitosan-modified cellulose whisker/elastomer composites in different pH environments.

    PubMed

    Wu, Tongfei; Su, Yuli; Chen, Biqiong

    2014-09-15

    Biomimetic polymer composites with water-active mechanically adaptive and shape-memory behaviour in different pH environments are synthesised by using chitosan-modified cellulose whiskers (CS-CWs) as the stimulus-responsive phase and thermoplastic polyurethane (TPU) as the resilient matrix. The effect of surface modification on the mechanically adaptive behaviour of CS-CW/TPU composites is investigated by using three representative solutions with various pH values. The results show that surface modification significantly enhances the modulus contrast under wet and dry conditions with the acidic solution as the stimulus, while maintaining the high modulus contrast with the basic solution as the stimulus. CS-CW/TPU composites also exhibit excellent shape-memory effects in all three solutions that are comparable to those pristine CW/TPU composites. Furthermore, activation of force generation in the stretched CS-CW/TPU composites by water absorption/desorption was observed. PMID:24976483

  4. An Adaptive Sequential Design for Model Discrimination and Parameter Estimation in Non-Linear Nested Models

    SciTech Connect

    Tommasi, C.; May, C.

    2010-09-30

    The DKL-optimality criterion has been recently proposed for the dual problem of model discrimination and parameter estimation, for the case of two rival models. A sequential version of the DKL-optimality criterion is herein proposed in order to discriminate and efficiently estimate more than two nested non-linear models. Our sequential method is inspired by the procedure of Biswas and Chaudhuri (2002), which is however useful only in the set up of nested linear models.

  5. Adaptive PD Tracking Control of Gimbal on Satellite Based on Parameter Revision

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Min; Zhao, Guo-Wei; Bai, Jun-Qing; Wang, Hao-Yu

    As key component of pointing and tracking mission of satellite, gimbal with two or more degree of freedom is usually mounted on the satellite in order to fulfill certain space mission, such as optical communication between satellites, target recognition, antenna with certain pointing direction and so on. In these missions, gimbal is mostly used to point to and track a space target or a given track. However, for most control method, because of their constant feedback parameter, the gimbal still track target with constant speed when the target is in high-speed or the satellite mounted with gimbal is suddenly undertaken shock. In fact, the gimbal could track target with different speed to improve pointing accuracy under particular circumstance. In order to solve the problem, an algorithm to revise feedback parameter is designed to be different functions of pointing angle error of gimbal. At last a simulation is carried out to verify the improvement of joint angle error using this algorithm under particular circumstance. The results proved that the joint angle error is efficiently decreased with feedback parameter revision.

  6. A new neuro-FDS definition for indirect adaptive control of unknown nonlinear systems using a method of parameter hopping.

    PubMed

    Boutalis, Yiannis; Theodoridis, Dimitris C; Christodoulou, Manolis A

    2009-04-01

    The indirect adaptive regulation of unknown nonlinear dynamical systems is considered in this paper. The method is based on a new neuro-fuzzy dynamical system (neuro-FDS) definition, which uses the concept of adaptive fuzzy systems (AFSs) operating in conjunction with high-order neural network functions (FHONNFs). Since the plant is considered unknown, we first propose its approximation by a special form of an FDS and then the fuzzy rules are approximated by appropriate HONNFs. Thus, the identification scheme leads up to a recurrent high-order neural network (RHONN), which however takes into account the fuzzy output partitions of the initial FDS. The proposed scheme does not require a priori experts' information on the number and type of input variable membership functions making it less vulnerable to initial design assumptions. Once the system is identified around an operation point, it is regulated to zero adaptively. Weight updating laws for the involved HONNFs are provided, which guarantee that both the identification error and the system states reach zero exponentially fast, while keeping all signals in the closed loop bounded. The existence of the control signal is always assured by introducing a novel method of parameter hopping, which is incorporated in the weight updating law. Simulations illustrate the potency of the method and comparisons with conventional approaches on benchmarking systems are given. Also, the applicability of the method is tested on a direct current (dc) motor system where it is shown that by following the proposed procedure one can obtain asymptotic regulation. PMID:19273046

  7. Rotor Position Sensorless Control and Its Parameter Sensitivity of Permanent Magnet Motor Based on Model Reference Adaptive System

    NASA Astrophysics Data System (ADS)

    Ohara, Masaki; Noguchi, Toshihiko

    This paper describes a new method for a rotor position sensorless control of a surface permanent magnet synchronous motor based on a model reference adaptive system (MRAS). This method features the MRAS in a current control loop to estimate a rotor speed and position by using only current sensors. This method as well as almost all the conventional methods incorporates a mathematical model of the motor, which consists of parameters such as winding resistances, inductances, and an induced voltage constant. Hence, the important thing is to investigate how the deviation of these parameters affects the estimated rotor position. First, this paper proposes a structure of the sensorless control applied in the current control loop. Next, it proves the stability of the proposed method when motor parameters deviate from the nominal values, and derives the relationship between the estimated position and the deviation of the parameters in a steady state. Finally, some experimental results are presented to show performance and effectiveness of the proposed method.

  8. Enabling the extended compact genetic algorithm for real-parameter optimization by using adaptive discretization.

    PubMed

    Chen, Ying-ping; Chen, Chao-Hong

    2010-01-01

    An adaptive discretization method, called split-on-demand (SoD), enables estimation of distribution algorithms (EDAs) for discrete variables to solve continuous optimization problems. SoD randomly splits a continuous interval if the number of search points within the interval exceeds a threshold, which is decreased at every iteration. After the split operation, the nonempty intervals are assigned integer codes, and the search points are discretized accordingly. As an example of using SoD with EDAs, the integration of SoD and the extended compact genetic algorithm (ECGA) is presented and numerically examined. In this integration, we adopt a local search mechanism as an optional component of our back end optimization engine. As a result, the proposed framework can be considered as a memetic algorithm, and SoD can potentially be applied to other memetic algorithms. The numerical experiments consist of two parts: (1) a set of benchmark functions on which ECGA with SoD and ECGA with two well-known discretization methods: the fixed-height histogram (FHH) and the fixed-width histogram (FWH) are compared; (2) a real-world application, the economic dispatch problem, on which ECGA with SoD is compared to other methods. The experimental results indicate that SoD is a better discretization method to work with ECGA. Moreover, ECGA with SoD works quite well on the economic dispatch problem and delivers solutions better than the best known results obtained by other methods in existence. PMID:20210600

  9. Adapting isostatic microbial growth parameters into non-isostatic models for use in dynamic ecosystems

    NASA Astrophysics Data System (ADS)

    Spangler, J.; Schulz, C. J.; Childers, G. W.

    2009-12-01

    Modeling microbial respiration and growth is an important tool for understanding many geochemical systems. The estimation of growth parameters relies on fitting experimental data to a selected model, such as the Monod equation or some variation, most often under batch or continuous culture conditions. While continuous culture conditions can be analogous to some natural environments, it often isn’t the case. More often, microorganisms are subject to fluctuating temperature, substrate concentrations, pH, water activity, and inhibitory compounds, to name a few. Microbial growth estimation under non-isothermal conditions has been possible through use of numerical solutions and has seen use in the field of food microbiology. In this study, numerical solutions were used to extend growth models under more non-isostatic conditions using momentary growth rate estimates. Using a model organism common in wastewater (Paracoccus denitrificans), growth and respiration rate parameters were estimated under varying static conditions (temperature, pH, electron donor/acceptor concentrations) and used to construct a non-isostatic growth model. After construction of the model, additional experiments were conducted to validate the model. These non-isostatic models hold the potential for allowing the prediction of cell biomass and respiration rates under a diverse array of conditions. By not restricting models to constant environmental conditions, the general applicability of the model can be greatly improved.

  10. Adaptive Neuro-Fuzzy Determination of the Effect of Experimental Parameters on Vehicle Agent Speed Relative to Vehicle Intruder

    PubMed Central

    Shamshirband, Shahaboddin; Banjanovic-Mehmedovic, Lejla; Bosankic, Ivan; Kasapovic, Suad; Abdul Wahab, Ainuddin Wahid Bin

    2016-01-01

    Intelligent Transportation Systems rely on understanding, predicting and affecting the interactions between vehicles. The goal of this paper is to choose a small subset from the larger set so that the resulting regression model is simple, yet have good predictive ability for Vehicle agent speed relative to Vehicle intruder. The method of ANFIS (adaptive neuro fuzzy inference system) was applied to the data resulting from these measurements. The ANFIS process for variable selection was implemented in order to detect the predominant variables affecting the prediction of agent speed relative to intruder. This process includes several ways to discover a subset of the total set of recorded parameters, showing good predictive capability. The ANFIS network was used to perform a variable search. Then, it was used to determine how 9 parameters (Intruder Front sensors active (boolean), Intruder Rear sensors active (boolean), Agent Front sensors active (boolean), Agent Rear sensors active (boolean), RSSI signal intensity/strength (integer), Elapsed time (in seconds), Distance between Agent and Intruder (m), Angle of Agent relative to Intruder (angle between vehicles °), Altitude difference between Agent and Intruder (m)) influence prediction of agent speed relative to intruder. The results indicated that distance between Vehicle agent and Vehicle intruder (m) and angle of Vehicle agent relative to Vehicle Intruder (angle between vehicles °) is the most influential parameters to Vehicle agent speed relative to Vehicle intruder. PMID:27219539

  11. Adaptive Neuro-Fuzzy Determination of the Effect of Experimental Parameters on Vehicle Agent Speed Relative to Vehicle Intruder.

    PubMed

    Shamshirband, Shahaboddin; Banjanovic-Mehmedovic, Lejla; Bosankic, Ivan; Kasapovic, Suad; Abdul Wahab, Ainuddin Wahid Bin

    2016-01-01

    Intelligent Transportation Systems rely on understanding, predicting and affecting the interactions between vehicles. The goal of this paper is to choose a small subset from the larger set so that the resulting regression model is simple, yet have good predictive ability for Vehicle agent speed relative to Vehicle intruder. The method of ANFIS (adaptive neuro fuzzy inference system) was applied to the data resulting from these measurements. The ANFIS process for variable selection was implemented in order to detect the predominant variables affecting the prediction of agent speed relative to intruder. This process includes several ways to discover a subset of the total set of recorded parameters, showing good predictive capability. The ANFIS network was used to perform a variable search. Then, it was used to determine how 9 parameters (Intruder Front sensors active (boolean), Intruder Rear sensors active (boolean), Agent Front sensors active (boolean), Agent Rear sensors active (boolean), RSSI signal intensity/strength (integer), Elapsed time (in seconds), Distance between Agent and Intruder (m), Angle of Agent relative to Intruder (angle between vehicles °), Altitude difference between Agent and Intruder (m)) influence prediction of agent speed relative to intruder. The results indicated that distance between Vehicle agent and Vehicle intruder (m) and angle of Vehicle agent relative to Vehicle Intruder (angle between vehicles °) is the most influential parameters to Vehicle agent speed relative to Vehicle intruder. PMID:27219539

  12. Reversible adaptation to photoinduced shape switching by oligomer-macrocycle interconversion with component selection in a three-state constitutional dynamic system.

    PubMed

    Vantomme, Ghislaine; Lehn, Jean-Marie

    2014-12-01

    Light irradiation of the molecular photoswitch 1-E causes isomerization into the 1-Z configuration stabilized by an internal hydrogen bond. 1-E bears aldehyde groups allowing for dynamic covalent reaction with linear diamines. On photoinduced E/Z shape switching of 1 in presence of diamines, the system undergoes interconversion between two states, a non-cyclic oligomeric one and a macrocyclic one, corresponding respectively to the E and Z configurations of 1. With a mixture of linear α,ω-diamines, 1-E yields non-selective dynamic oligomers by random incorporation of diamine components. Photoswitching to the 1-Z form leads to constitutional adaptation with preferential formation of the macrocycle incorporating the best suited diamine, H2 N(CH2 )7 NH2 . In presence of metal cations, the E form switches from its unbound W shape to its coordinated U shape and yields the macrocycle resulting from the selective incorporation of the diamine H2 NCH2 CH2 OCH2 CH2 NH2 that contains an additional O coordination site. Taken together, the results obtained describe constitutional adaptation in a triple state system: an oligomeric one and two different macrocyclic ones generated in response to two orthogonal agents, a physical stimulus, light, or a chemical effector, metal cations. These three states present, towards the incorporation of diamine components, respectively no selection, photoselection and metalloselection. PMID:25297846

  13. Rotor-bearing system integrated with shape memory alloy springs for ensuring adaptable dynamics and damping enhancement-Theory and experiment

    NASA Astrophysics Data System (ADS)

    Enemark, Søren; Santos, Ilmar F.

    2016-05-01

    Helical pseudoelastic shape memory alloy (SMA) springs are integrated into a dynamic system consisting of a rigid rotor supported by passive magnetic bearings. The aim is to determine the utility of SMAs for vibration attenuation via their mechanical hysteresis, and for adaptation of the dynamic behaviour via their temperature dependent stiffness properties. The SMA performance, in terms of vibration attenuation and adaptability, is compared to a benchmark configuration of the system having steel springs instead of SMA springs. A theoretical multidisciplinary approach is used to quantify the weakly nonlinear coupled dynamics of the rotor-bearing system. The nonlinear forces from the thermo-mechanical shape memory alloy springs and from the passive magnetic bearings are coupled to the rotor and bearing housing dynamics. The equations of motion describing rotor tilt and bearing housing lateral motion are solved in the time domain. The SMA behaviour is also described by the complex modulus to form approximative equations of motion, which are solved in the frequency domain using continuation techniques. Transient responses, ramp-ups and steady-state frequency responses of the system are investigated experimentally and numerically. By using the proper SMA temperature, vibration reductions up to around 50 percent can be achieved using SMAs instead of steel. Regarding system adaptability, both the critical speeds, the mode shapes and the modes' sensitivity to disturbances (e.g. imbalance) highly depend on the SMA temperature. Examples show that vibration reduction at constant rotational speeds up to around 75 percent can be achieved by changing the SMA temperature, primarily because of stiffness change, whereas hysteresis only limits large vibrations. The model is able to capture and explain the experimental dynamic behaviour.

  14. Does conflict help or hurt cognitive control? Initial evidence for an inverted U-shape relationship between perceived task difficulty and conflict adaptation

    PubMed Central

    van Steenbergen, Henk; Band, Guido P. H.; Hommel, Bernhard

    2015-01-01

    Sequential modulation of congruency effects in conflict tasks indicates that cognitive control quickly adapts to changing task demands. We investigated in four experiments how this behavioral congruency-sequence effect relates to different levels of perceived task difficulty in a flanker and a Stroop task. In addition, online measures of pupil diameter were used as a physiological index of effort mobilization. Consistent with motivational accounts predicting that increased levels of perceived task difficulty will increase effort mobilization only up to a certain limit, reliable dynamic conflict-driven adjustment in cognitive control was only observed when task difficulty was relatively low. Instead, tasks tentatively associated with high levels of difficulty showed no or reversed conflict adaptation. Although the effects could not be linked consistently to effects in self-reported task difficulty in all experiments, regression analyses showed associations between perceived task difficulty and conflict adaptation in some of the experiments, which provides some initial evidence for an inverted U-shape relationship between perceived difficulty and adaptations in cognitive control. Furthermore, high levels of task difficulty were associated with a conflict-driven reduction in pupil dilation, suggesting that pupil dilation can be used as a physiological marker of mental overload. Our findings underscore the importance of developing models that are grounded in motivational accounts of cognitive control. PMID:26217287

  15. Functional adaptations in the craniofacial morphology of Malagasy primates: shape variations associated with gummivory in the family Cheirogaleidae.

    PubMed

    Viguier, Bénédicte

    2004-12-01

    The infraorder Lemuriformes is characterized by a high level of homoplasy that clouds the evolutionary signal. The analysis of the morphological disparity of the Malagasy primates' crania and mandibles demonstrates the high determinism of functional specializations and developmental constraints, regardless of the phylogeny. In the present work, the weight of functional constraints linked to diet--a putative source of homoplasy--is analyzed first at the level of the infraorder Lemuriformes as a whole, and secondly at the level of a single family, the Cheirogaleidae, chosen because it contains taxa with two different diets (omnivory and gummivory). Malagasy primates are characterized by a great variety of dietary habits: some of them are omnivores, folivores, frugivores, gummivores, insectivores or even specialized hard-object feeders. All cheirogaleids feed on tree exudates, but while gum consumption is occasional or limited for Microcebus, Cheirogaleus and Mirza, gums are the dominant food source for Phaner and Allocebus. Craniofacial shape variations are analyzed using geometric morphometrics: methods based on landmark identification (Procrustes superimpositions) are chosen for cranium shape analysis, and methods based on outline decomposition (elliptical Fourier functions) for study of mandible shape. The morphospaces obtained at the level of the infraorder appear to be highly constrained by dietary habits, especially in the case of the mandibles. At the finer level of the family Cheirogaleidae, the analyses permit (1) separation of craniomandibular shape variation associated with the two dietary categories and (2) among the omnivorous category, to distinguish variation associated with the percentage of gum consumption. PMID:15646283

  16. A fuzzy adaptive network approach to parameter estimation in cases where independent variables come from an exponential distribution

    NASA Astrophysics Data System (ADS)

    Dalkilic, Turkan Erbay; Apaydin, Aysen

    2009-11-01

    In a regression analysis, it is assumed that the observations come from a single class in a data cluster and the simple functional relationship between the dependent and independent variables can be expressed using the general model; Y=f(X)+[epsilon]. However; a data cluster may consist of a combination of observations that have different distributions that are derived from different clusters. When faced with issues of estimating a regression model for fuzzy inputs that have been derived from different distributions, this regression model has been termed the [`]switching regression model' and it is expressed with . Here li indicates the class number of each independent variable and p is indicative of the number of independent variables [J.R. Jang, ANFIS: Adaptive-network-based fuzzy inference system, IEEE Transaction on Systems, Man and Cybernetics 23 (3) (1993) 665-685; M. Michel, Fuzzy clustering and switching regression models using ambiguity and distance rejects, Fuzzy Sets and Systems 122 (2001) 363-399; E.Q. Richard, A new approach to estimating switching regressions, Journal of the American Statistical Association 67 (338) (1972) 306-310]. In this study, adaptive networks have been used to construct a model that has been formed by gathering obtained models. There are methods that suggest the class numbers of independent variables heuristically. Alternatively, in defining the optimal class number of independent variables, the use of suggested validity criterion for fuzzy clustering has been aimed. In the case that independent variables have an exponential distribution, an algorithm has been suggested for defining the unknown parameter of the switching regression model and for obtaining the estimated values after obtaining an optimal membership function, which is suitable for exponential distribution.

  17. Complex interplay between neutral and adaptive evolution shaped differential genomic background and disease susceptibility along the Italian peninsula

    PubMed Central

    Sazzini, Marco; Gnecchi Ruscone, Guido Alberto; Giuliani, Cristina; Sarno, Stefania; Quagliariello, Andrea; De Fanti, Sara; Boattini, Alessio; Gentilini, Davide; Fiorito, Giovanni; Catanoso, Mariagrazia; Boiardi, Luigi; Croci, Stefania; Macchioni, Pierluigi; Mantovani, Vilma; Di Blasio, Anna Maria; Matullo, Giuseppe; Salvarani, Carlo; Franceschi, Claudio; Pettener, Davide; Garagnani, Paolo; Luiselli, Donata

    2016-01-01

    The Italian peninsula has long represented a natural hub for human migrations across the Mediterranean area, being involved in several prehistoric and historical population movements. Coupled with a patchy environmental landscape entailing different ecological/cultural selective pressures, this might have produced peculiar patterns of population structure and local adaptations responsible for heterogeneous genomic background of present-day Italians. To disentangle this complex scenario, genome-wide data from 780 Italian individuals were generated and set into the context of European/Mediterranean genomic diversity by comparison with genotypes from 50 populations. To maximize possibility of pinpointing functional genomic regions that have played adaptive roles during Italian natural history, our survey included also ~250,000 exomic markers and ~20,000 coding/regulatory variants with well-established clinical relevance. This enabled fine-grained dissection of Italian population structure through the identification of clusters of genetically homogeneous provinces and of genomic regions underlying their local adaptations. Description of such patterns disclosed crucial implications for understanding differential susceptibility to some inflammatory/autoimmune disorders, coronary artery disease and type 2 diabetes of diverse Italian subpopulations, suggesting the evolutionary causes that made some of them particularly exposed to the metabolic and immune challenges imposed by dietary and lifestyle shifts that involved western societies in the last centuries. PMID:27582244

  18. Complex interplay between neutral and adaptive evolution shaped differential genomic background and disease susceptibility along the Italian peninsula.

    PubMed

    Sazzini, Marco; Gnecchi Ruscone, Guido Alberto; Giuliani, Cristina; Sarno, Stefania; Quagliariello, Andrea; De Fanti, Sara; Boattini, Alessio; Gentilini, Davide; Fiorito, Giovanni; Catanoso, Mariagrazia; Boiardi, Luigi; Croci, Stefania; Macchioni, Pierluigi; Mantovani, Vilma; Di Blasio, Anna Maria; Matullo, Giuseppe; Salvarani, Carlo; Franceschi, Claudio; Pettener, Davide; Garagnani, Paolo; Luiselli, Donata

    2016-01-01

    The Italian peninsula has long represented a natural hub for human migrations across the Mediterranean area, being involved in several prehistoric and historical population movements. Coupled with a patchy environmental landscape entailing different ecological/cultural selective pressures, this might have produced peculiar patterns of population structure and local adaptations responsible for heterogeneous genomic background of present-day Italians. To disentangle this complex scenario, genome-wide data from 780 Italian individuals were generated and set into the context of European/Mediterranean genomic diversity by comparison with genotypes from 50 populations. To maximize possibility of pinpointing functional genomic regions that have played adaptive roles during Italian natural history, our survey included also ~250,000 exomic markers and ~20,000 coding/regulatory variants with well-established clinical relevance. This enabled fine-grained dissection of Italian population structure through the identification of clusters of genetically homogeneous provinces and of genomic regions underlying their local adaptations. Description of such patterns disclosed crucial implications for understanding differential susceptibility to some inflammatory/autoimmune disorders, coronary artery disease and type 2 diabetes of diverse Italian subpopulations, suggesting the evolutionary causes that made some of them particularly exposed to the metabolic and immune challenges imposed by dietary and lifestyle shifts that involved western societies in the last centuries. PMID:27582244

  19. Inversions and adaptation to the plant toxin ouabain shape DNA sequence variation within and between chromosomal inversions of Drosophila subobscura.

    PubMed Central

    Pegueroles, Cinta; Ferrés-Coy, Albert; Martí-Solano, Maria; Aquadro, Charles F; Pascual, Marta; Mestres, Francesc

    2016-01-01

    Adaptation is defined as an evolutionary process allowing organisms to succeed in certain habitats or conditions. Chromosomal inversions have the potential to be key in the adaptation processes, since they can contribute to the maintenance of favoured combinations of adaptive alleles through reduced recombination between individuals carrying different inversions. We have analysed six genes (Pif1A, Abi, Sqd, Yrt, Atpα and Fmr1), located inside and outside three inversions of the O chromosome in European populations of Drosophila subobscura. Genetic differentiation was significant between inversions despite extensive recombination inside inverted regions, irrespective of gene distance to the inversion breakpoints. Surprisingly, the highest level of genetic differentiation between arrangements was found for the Atpα gene, which is located outside the O1 and O7 inversions. Two derived unrelated arrangements (O3+4+1 and O3+4+7) are nearly fixed for several amino acid substitutions at the Atpα gene that have been described to confer resistance in other species to the cardenolide ouabain, a plant toxin capable of blocking ATPases. Similarities in the Atpα variants, conferring ouabain resistance in both arrangements, may be the result of convergent substitution and be favoured in response to selective pressures presumably related to the presence of plants containing ouabain in the geographic locations where both inversions are present. PMID:27029337

  20. Distributed parameter system coupled ARMA expansion identification and adaptive parallel IIR filtering - A unified problem statement. [Auto Regressive Moving-Average

    NASA Technical Reports Server (NTRS)

    Johnson, C. R., Jr.; Balas, M. J.

    1980-01-01

    A novel interconnection of distributed parameter system (DPS) identification and adaptive filtering is presented, which culminates in a common statement of coupled autoregressive, moving-average expansion or parallel infinite impulse response configuration adaptive parameterization. The common restricted complexity filter objectives are seen as similar to the reduced-order requirements of the DPS expansion description. The interconnection presents the possibility of an exchange of problem formulations and solution approaches not yet easily addressed in the common finite dimensional lumped-parameter system context. It is concluded that the shared problems raised are nevertheless many and difficult.

  1. Adaptive approach for on-board impedance parameters and voltage estimation of lithium-ion batteries in electric vehicles

    NASA Astrophysics Data System (ADS)

    Farmann, Alexander; Waag, Wladislaw; Sauer, Dirk Uwe

    2015-12-01

    Robust algorithms using reduced order equivalent circuit model (ECM) for an accurate and reliable estimation of battery states in various applications become more popular. In this study, a novel adaptive, self-learning heuristic algorithm for on-board impedance parameters and voltage estimation of lithium-ion batteries (LIBs) in electric vehicles is introduced. The presented approach is verified using LIBs with different composition of chemistries (NMC/C, NMC/LTO, LFP/C) at different aging states. An impedance-based reduced order ECM incorporating ohmic resistance and a combination of a constant phase element and a resistance (so-called ZARC-element) is employed. Existing algorithms in vehicles are much more limited in the complexity of the ECMs. The algorithm is validated using seven day real vehicle data with high temperature variation including very low temperatures (from -20 °C to +30 °C) at different Depth-of-Discharges (DoDs). Two possibilities to approximate both ZARC-elements with finite number of RC-elements on-board are shown and the results of the voltage estimation are compared. Moreover, the current dependence of the charge-transfer resistance is considered by employing Butler-Volmer equation. Achieved results indicate that both models yield almost the same grade of accuracy.

  2. Numerical parameter studies of 3D melt flow and interface shape for directional solidification of silicon in a traveling magnetic field

    NASA Astrophysics Data System (ADS)

    Vizman, D.; Dadzis, K.; Friedrich, J.

    2013-10-01

    The role of various growth and process conditions (Lorentz force, temperature gradients in the melt and the crystal, steady-state crystallization velocity) in directional solidification of multicrystalline silicon in a traveling magnetic field is analyzed for a research-scale furnace (melt size of 22×22×11 cm3). The influence on the melt flow pattern, the typical melt flow velocity, the oscillation amplitude of the velocity and the temperature, the shape of the crystallization interface is determined using three-dimensional (3D) numerical calculations with the STHAMAS3D software and a local quasi steady-state model. It was found that both the interface shape and the melt flow are sensitive to the variation of the considered growth and process parameters.

  3. Application of wavelet transforms to determine peak shape parameters for interference detection in graphite-furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Sadler, D. A.; Littlejohn, D.; Boulo, P. R.; Soraghan, J. S.

    1998-08-01

    A procedure to quantify the shape of the absorbance-time profile, obtained during graphite furnace atomic absorption spectrometry, has been used to detect interference effects caused by the presence of a concomitant salt. The quantification of the absorption profile is achieved through the use of the Lipschitz regularity, α0, obtained from the wavelet transform of the absorbance-time profile. The temporal position of certain features and their associated values of α0 provide a unique description of the shape of the absorbance-time profile. Changes to the position or values of α0 between standard and sample atomizations may be indicative of uncorrected interference effects. A weak, but linear, dependence was found of the value of α0 upon the analyte concentration for Cr and Cu. The ability of the Lipschitz regularity to detect interference effects was illustrated for Pb, Se and Cu. For Pb, the lowest concentration of NaCl added, 0.005% m/v, changed both the values of α0 and the peak height absorbance. For Se, no change in the peak height and peak area absorbance signals was detected up to a NaCl concentration of 0.25% m/v. The values of the associated Lipschitz regularities were found to be invariant to NaCl concentration up to this value. For Cu, a concentration of 0.05% m/v NaCl reduced the peak height and peak area absorbance signals by approximately 25% and significantly altered the values of α0.

  4. SU-C-9A-01: Parameter Optimization in Adaptive Region-Growing for Tumor Segmentation in PET

    SciTech Connect

    Tan, S; Xue, M; Chen, W; D'Souza, W; Lu, W; Li, H

    2014-06-01

    Purpose: To design a reliable method to determine the optimal parameter in the adaptive region-growing (ARG) algorithm for tumor segmentation in PET. Methods: The ARG uses an adaptive similarity criterion m - fσ ≤ I-PET ≤ m + fσ, so that a neighboring voxel is appended to the region based on its similarity to the current region. When increasing the relaxing factor f (f ≥ 0), the resulting volumes monotonically increased with a sharp increase when the region just grew into the background. The optimal f that separates the tumor from the background is defined as the first point with the local maximum curvature on an Error function fitted to the f-volume curve. The ARG was tested on a tumor segmentation Benchmark that includes ten lung cancer patients with 3D pathologic tumor volume as ground truth. For comparison, the widely used 42% and 50% SUVmax thresholding, Otsu optimal thresholding, Active Contours (AC), Geodesic Active Contours (GAC), and Graph Cuts (GC) methods were tested. The dice similarity index (DSI), volume error (VE), and maximum axis length error (MALE) were calculated to evaluate the segmentation accuracy. Results: The ARG provided the highest accuracy among all tested methods. Specifically, the ARG has an average DSI, VE, and MALE of 0.71, 0.29, and 0.16, respectively, better than the absolute 42% thresholding (DSI=0.67, VE= 0.57, and MALE=0.23), the relative 42% thresholding (DSI=0.62, VE= 0.41, and MALE=0.23), the absolute 50% thresholding (DSI=0.62, VE=0.48, and MALE=0.21), the relative 50% thresholding (DSI=0.48, VE=0.54, and MALE=0.26), OTSU (DSI=0.44, VE=0.63, and MALE=0.30), AC (DSI=0.46, VE= 0.85, and MALE=0.47), GAC (DSI=0.40, VE= 0.85, and MALE=0.46) and GC (DSI=0.66, VE= 0.54, and MALE=0.21) methods. Conclusions: The results suggest that the proposed method reliably identified the optimal relaxing factor in ARG for tumor segmentation in PET. This work was supported in part by National Cancer Institute Grant R01 CA172638; The

  5. Sports teams as complex adaptive systems: manipulating player numbers shapes behaviours during football small-sided games.

    PubMed

    Silva, Pedro; Vilar, Luís; Davids, Keith; Araújo, Duarte; Garganta, Júlio

    2016-01-01

    Small-sided and conditioned games (SSCGs) in sport have been modelled as complex adaptive systems. Research has shown that the relative space per player (RSP) formulated in SSCGs can impact on emergent tactical behaviours. In this study we adopted a systems orientation to analyse how different RSP values, obtained through manipulations of player numbers, influenced four measures of interpersonal coordination observed during performance in SSCGs. For this purpose we calculated positional data (GPS 15 Hz) from ten U-15 football players performing in three SSCGs varying in player numbers (3v3, 4v4 and 5v5). Key measures of SSCG system behaviours included values of (1) players' dispersion, (2) teams' separateness, (3) coupling strength and time delays between participants' emerging movements, respectively. Results showed that values of participants' dispersion increased, but the teams' separateness remained identical across treatments. Coupling strength and time delay also showed consistent values across SSCGs. These results exemplified how complex adaptive systems, like football teams, can harness inherent degeneracy to maintain similar team spatial-temporal relations with opponents through changes in inter-individual coordination modes (i.e., players' dispersion). The results imply that different team behaviours might emerge at different ratios of field dimension/player numbers. Therefore, sport pedagogists should carefully evaluate the effects of changing RSP in SSCGs as a way of promoting increased or decreased pressure on players. PMID:27026887

  6. Superordinate Shape Classification Using Natural Shape Statistics

    ERIC Educational Resources Information Center

    Wilder, John; Feldman, Jacob; Singh, Manish

    2011-01-01

    This paper investigates the classification of shapes into broad natural categories such as "animal" or "leaf". We asked whether such coarse classifications can be achieved by a simple statistical classification of the shape skeleton. We surveyed databases of natural shapes, extracting shape skeletons and tabulating their parameters within each…

  7. Concept for image-guided vitreo-retinal fs-laser surgery: adaptive optics and optical coherence tomography for laser beam shaping and positioning

    NASA Astrophysics Data System (ADS)

    Matthias, Ben; Brockmann, Dorothee; Hansen, Anja; Horke, Konstanze; Knoop, Gesche; Gewohn, Timo; Zabic, Miroslav; Krüger, Alexander; Ripken, Tammo

    2015-03-01

    Fs-lasers are well established in ophthalmic surgery as high precision tools for corneal flap cutting during laser in situ keratomileusis (LASIK) and increasingly utilized for cutting the crystalline lens, e.g. in assisting cataract surgery. For addressing eye structures beyond the cornea, an intraoperative depth resolved imaging is crucial to the safety and success of the surgical procedure due to interindividual anatomical disparities. Extending the field of application even deeper to the posterior eye segment, individual eye aberrations cannot be neglected anymore and surgery with fs-laser is impaired by focus degradation. Our demonstrated concept for image-guided vitreo-retinal fs-laser surgery combines adaptive optics (AO) for spatial beam shaping and optical coherence tomography (OCT) for focus positioning guidance. The laboratory setup comprises an adaptive optics assisted 800 nm fs-laser system and is extended by a Fourier domain optical coherence tomography system. Phantom structures are targeted, which mimic tractional epiretinal membranes in front of excised porcine retina within an eye model. AO and OCT are set up to share the same scanning and focusing optics. A Hartmann-Shack sensor is employed for aberration measurement and a deformable mirror for aberration correction. By means of adaptive optics the threshold energy for laser induced optical breakdown is lowered and cutting precision is increased. 3D OCT imaging of typical ocular tissue structures is achieved with sufficient resolution and the images can be used for orientation of the fs-laser beam. We present targeted dissection of the phantom structures and its evaluation regarding retinal damage.

  8. Shaping of adaptive immune responses to soluble proteins by TLR agonists: a role for IFN-alpha/beta.

    PubMed

    Durand, Vanessa; Wong, Simon Yc; Tough, David F; Le Bon, Agnes

    2004-12-01

    Toll-like receptors (TLR) are believed to play a major role in the recognition of invading organisms, although their ability to shape immune responses is not completely understood. Our aim was to investigate in vivo the effect of different TLR stimuli on the generation of antibody responses and the induction of CD8+ T-cell cross-priming after immunization with soluble protein antigens. While all TLR agonists tested elicited the production of immunomodulatory cytokines, marked differences were observed in their ability to stimulate antigen-specific immune responses. Zymosan, poly(I:C) and CpG DNA, which signal through TLR2/6, 3 and 9, respectively, were found to strongly induce the production of IgG2a antibodies, whereas R-848 (TLR7) and LPS (TLR4) did so much more weakly. In contrast, LPS, poly(I:C) and CpG DNA, but not zymosan, induced functional CD8+ T-cell responses against OVA; peptidoglycan (TLR2/?) and R-848 were also ineffective in stimulating cross-priming. Experiments using IFN-alpha/beta R-deficient mice showed that the induction of cross-priming by LPS and poly(I:C) was abrogated in the absence of IFN-alpha/beta signalling, and induction by CpG DNA was greatly reduced. Overall, our results identify LPS as another TLR agonist that is able to generate functional cross-priming against a soluble protein antigen. In addition, our results demonstrate that the ability of TLR stimuli to initiate CD8+ T-cell responses against soluble protein antigens is largely dependent on the IFN-alpha/beta signalling pathway. PMID:15550117

  9. Effect of software version and parameter settings on the marginal and internal adaptation of crowns fabricated with the CAD/CAM system

    PubMed Central

    SHIM, Ji Suk; Jin Sook, LEE; Jeong Yol, LEE; CHOI, Yeon Jo; SHIN, Sang Wan; Jae Jun, RYU

    2015-01-01

    Objective This study investigated the marginal and internal adaptation of individual dental crowns fabricated using a CAD/CAM system (Sirona’s BlueCam), also evaluating the effect of the software version used, and the specific parameter settings in the adaptation of crowns. Material and Methods Forty digital impressions of a master model previously prepared were acquired using an intraoral scanner and divided into four groups based on the software version and on the spacer settings used. The versions 3.8 and 4.2 of the software were used, and the spacer parameter was set at either 40 μm or 80 μm. The marginal and internal fit of the crowns were measured using the replica technique, which uses a low viscosity silicone material that simulates the thickness of the cement layer. The data were analyzed using a Friedman two-way analysis of variance (ANOVA) and paired t-tests with significance level set at p<0.05. Results The two-way ANOVA analysis showed the software version (p<0.05) and the spacer parameter (p<0.05) significantly affected the crown adaptation. The crowns designed with the version 4.2 of the software showed a better fit than those designed with the version 3.8, particularly in the axial wall and in the inner margin. The spacer parameter was more accurately represented in the version 4.2 of the software than in the version 3.8. In addition, the use of the version 4.2 of the software combined with the spacer parameter set at 80 μm showed the least variation. On the other hand, the outer margin was not affected by the variables. Conclusion Compared to the version 3.8 of the software, the version 4.2 can be recommended for the fabrication of well-fitting crown restorations, and for the appropriate regulation of the spacer parameter. PMID:26537722

  10. Line parameters including temperature dependences of air- and self-broadened line shapes of 12C16O2: 2.06-μm region

    NASA Astrophysics Data System (ADS)

    Benner, D. Chris; Devi, V. Malathy; Sung, Keeyoon; Brown, Linda R.; Miller, Charles E.; Payne, Vivienne H.; Drouin, Brian J.; Yu, Shanshan; Crawford, Timothy J.; Mantz, Arlan W.; Smith, Mary Ann H.; Gamache, Robert R.

    2016-08-01

    This study reports the results from analyzing a number of high resolution, high signal-to-noise ratio (S/N) spectra in the 2.06-μm spectral region for pure CO2 and mixtures of CO2 in dry air. A multispectrum nonlinear least squares curve fitting technique has been used to retrieve the various spectral line parameters. The dataset includes 27 spectra: ten pure CO2, two 99% 13C-enriched CO2 and fifteen spectra of mixtures of 12C-enriched CO2 in dry air. The spectra were recorded at various gas sample temperatures between 170 and 297 K. The absorption path lengths range from 0.347 to 49 m. The sample pressures for the pure CO2 spectra varied from 1.1 to 594 Torr; for the two 13CO2 spectra the pressures were ∼10 and 146 Torr. For the air-broadened spectra, the pressures of the gas mixtures varied between 200 and 711 Torr with CO2 volume mixing ratios ranging from 0.014% to 0.203%. The multispectrum fitting technique was applied to fit simultaneously all these spectra to retrieve consistent set of line positions, intensities, and line shape parameters including their temperature dependences; for this, the Voigt line shape was modified to include line mixing (via the relaxation matrix formalism) and quadratic speed dependence. The new results are compared to select published values, including recent ab initio calculations. These results are required to retrieve the column averaged dry air mole fraction (XCO2) from space-based observations, such as the Orbiting Carbon Observatory-2 (OCO-2) satellite mission that NASA launched in July 2014.

  11. An Empirical Evaluation of the Slip Correction in the Four Parameter Logistic Models with Computerized Adaptive Testing

    ERIC Educational Resources Information Center

    Yen, Yung-Chin; Ho, Rong-Guey; Laio, Wen-Wei; Chen, Li-Ju; Kuo, Ching-Chin

    2012-01-01

    In a selected response test, aberrant responses such as careless errors and lucky guesses might cause error in ability estimation because these responses do not actually reflect the knowledge that examinees possess. In a computerized adaptive test (CAT), these aberrant responses could further cause serious estimation error due to dynamic item…

  12. Tolerable Variation in Item Parameter Estimates for Linear and Adaptive Computer-Based Testing. Research Report No. 04-28

    ERIC Educational Resources Information Center

    Rizavi, Saba; Way, Walter D.; Davey, Tim; Herbert, Erin

    2004-01-01

    Item parameter estimates vary for a variety of reasons, including estimation error, characteristics of the examinee samples, and context effects (e.g., item location effects, section location effects, etc.). Although we expect variation based on theory, there is reason to believe that observed variation in item parameter estimates exceeds what…

  13. The relation between lattice parameters and very low twinning stress in Ni50Mn25+x Ga25-x magnetic shape memory alloys

    NASA Astrophysics Data System (ADS)

    Straka, L.; Drahokoupil, J.; Pacherová, O.; Fabiánová, K.; Kopecký, V.; Seiner, H.; Hänninen, H.; Heczko, O.

    2016-02-01

    In search of the origins of the extraordinary low twinning stress of Ni-Mn-Ga 10M martensite, we studied the temperature induced changes in lattice parameters of Ni50Mn25+x Ga25-x (x = 2.7-3.9) single crystal samples and compared them with twinning stress dependences. The alloys exhibited transformation to five-layered (10M) martensite structure (cubic to monoclinic) between 297 to 328 K and exhibited the magnetic shape memory effect in martensite. The structural changes were monitored using x-ray diffraction in the temperature range 200-343 K. The 10M structure was approximated by monoclinic lattice, a = b > c, γ > 90° with the coordinates derived from the cubic unit cell of the parent L21 phase. The lattice parameters γ and c/a correlate well with the universal linear increase of twinning stress of type 1 twins with decreasing temperature. On the contrary, the twinning stress is not affected by differences between a and b and thus a/b twins seem to play no role in a - c twin boundary motion resulting in magnetically induced reorientation.

  14. Line parameters including temperature dependences of self- and air-broadened line shapes of 12C16O2: 1.6-μm region

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Sung, Keeyoon; Brown, Linda R.; Crawford, Timothy J.; Miller, Charles E.; Drouin, Brian J.; Payne, Vivienne H.; Yu, Shanshan; Smith, Mary Ann H.; Mantz, Arlan W.; Gamache, Robert R.

    2016-07-01

    Pressure-broadened line shapes in the 30013←00001 (ν1+4 ν20 +ν3) band of 12C16O2 at 6228 cm-1 are reanalyzed using new spectra recorded with sample temperatures down to 170 K. High resolution, high signal-to-noise (S/N) laboratory measurements of line shapes (Lorentz air- and self-broadened half-width coefficients, pressure-shift coefficients and off-diagonal relaxation matrix element coefficients) as a function of gas sample temperatures for various pressures and volume mixing ratios are presented. The spectra were recorded using two different Fourier transform spectrometers (FTS): (1) the McMath-Pierce FTS located at the National Solar Observatory on Kitt Peak, Arizona (and reported in Devi et al., J Mol Spectrosc 2007;245:52-80) and, (2) the Bruker IFS-125HR FTS at the Jet Propulsion Laboratory in Pasadena, California. The 19 spectra taken at Kitt Peak were all recorded near room temperature while the 27 Bruker spectra were acquired both at room temperature and colder temperatures (170-296 K). Various spectral resolutions (0.004-0.011 cm-1), absorption path lengths (2.46-121 m) and CO2 samples (natural and 12C-enriched) were included in the dataset. To maximize the accuracies of the various retrieved line parameters, a multispectrum nonlinear least squares spectrum fitting software program was used to adjust the ro-vibrational constants (G,B,D etc.) and intensity parameters (including Herman-Wallis terms) instead of directly measuring the individual line positions and intensities. To minimize systematic residuals, line mixing (via off-diagonal relaxation matrix elements) and quadratic speed dependence parameters were included in the analysis. Contributions from other weakly absorbing bands: the 30013←00001 and 30012←00001 bands of 13C16O2, the 30013←00001 band of 12C16O18O, hot bands 31113←01101 and 32212←02201 of 12C16O2, as well as the 40013←10001 and the 40014←10002 bands of 12C16O2, present within the fitted interval were also measured

  15. A shape-adaptive thin-film-based approach for 50% high-efficiency energy generation through micro-grating sliding electrification.

    PubMed

    Zhu, Guang; Zhou, Yu Sheng; Bai, Peng; Meng, Xian Song; Jing, Qingshen; Chen, Jun; Wang, Zhong Lin

    2014-06-18

    Effectively harvesting ambient mechanical energy is the key for realizing self-powered and autonomous electronics, which addresses limitations of batteries and thus has tremendous applications in sensor networks, wireless devices, and wearable/implantable electronics, etc. Here, a thin-film-based micro-grating triboelectric nanogenerator (MG-TENG) is developed for high-efficiency power generation through conversion of mechanical energy. The shape-adaptive MG-TENG relies on sliding electrification between complementary micro-sized arrays of linear grating, which offers a unique and straightforward solution in harnessing energy from relative sliding motion between surfaces. Operating at a sliding velocity of 10 m/s, a MG-TENG of 60 cm(2) in overall area, 0.2 cm(3) in volume and 0.6 g in weight can deliver an average output power of 3 W (power density of 50 mW cm(-2) and 15 W cm(-3)) at an overall conversion efficiency of ∼ 50%, making it a sufficient power supply to regular electronics, such as light bulbs. The scalable and cost-effective MG-TENG is practically applicable in not only harvesting various mechanical motions but also possibly power generation at a large scale. PMID:24692147

  16. Methodology to automatically detect abnormal values of vital parameters in anesthesia time-series: Proposal for an adaptable algorithm.

    PubMed

    Lamer, Antoine; Jeanne, Mathieu; Marcilly, Romaric; Kipnis, Eric; Schiro, Jessica; Logier, Régis; Tavernier, Benoît

    2016-06-01

    Abnormal values of vital parameters such as hypotension or tachycardia may occur during anesthesia and may be detected by analyzing time-series data collected during the procedure by the Anesthesia Information Management System. When crossed with other data from the Hospital Information System, abnormal values of vital parameters have been linked with postoperative morbidity and mortality. However, methods for the automatic detection of these events are poorly documented in the literature and differ between studies, making it difficult to reproduce results. In this paper, we propose a methodology for the automatic detection of abnormal values of vital parameters. This methodology uses an algorithm allowing the configuration of threshold values for any vital parameters as well as the management of missing data. Four examples illustrate the application of the algorithm, after which it is applied to three vital signs (heart rate, SpO2, and mean arterial pressure) to all 2014 anesthetic records at our institution. PMID:26817405

  17. Adaptations of the reed frog Hyperolius viridiflavus (Amphibia, Anura, Hyperoliidae) to its arid environment. VII. The heat budget of Hyperolius viridiflavus nitidulus and the evolution of an optimized body shape.

    PubMed

    Kobelt, F; Linsenmair, K E

    1995-01-01

    Estivating reed frogs of the superspecies Hyperolius viridiflavus are extraordinarily resistant to the highly adverse climatic conditions prevailing in their African savanna habitats during dry season (air temperature up to 45 degrees C, solar radiation load up to 1000 W.m-2, no water replenishment possible for up to 3 months). They are able to withstand such climatic stress at their exposed estivation sites on dry plants without evaporative cooling. We developed a heat budget model to understand the mechanisms of how an anuran can achieve this unique tolerance, and which allows us to predict the anuran's core and surface temperature for a given set of environmental parameters, to within 4% of the measured values. The model makes it possible to quantify some of the adaptive mechanisms for survival in semiarid habitats by comparing H. viridiflavus with anurans (H. tuberilinguis and Rana pipiens) of less stressful habitats. To minimize heat gain and maximize heat loss from the frog, the following points were important with regard to avoiding lethal heat stress during estivation: 1) solar heat load is reduced by an extraordinarily high skin reflectivity for solar radiation of up to 0.65 under laboratory and even higher in the field under dry season conditions. 2) The half-cylindrical body shape of H. viridiflavus seems to be optimized for estivation compared to the hemispheroidal shape usually found for anurans in moist habitats. A half-cylinder can be positioned relative to the sun so that large surface areas for conductive and convective heat loss are shielded by a small area exposed to direct solar radiation. 3) Another important contribution of body shape is a high body surface area to body mass ratio, as found in the estivating subadult H. viridiflavus (snout-vent lengths of 14-20 mm and body weights of 350-750 mg) compared to adult frogs (24-30 mm, 1000-2500 mg) which have never been observed to survive a dry season. 4) These mechanisms strongly couple core

  18. Line shape parameters of PH3 transitions in the Pentad near 4-5 μm: Self-broadened widths, shifts, line mixing and speed dependence

    NASA Astrophysics Data System (ADS)

    Malathy Devi, V.; Benner, D. Chris; Kleiner, Isabelle; Sams, Robert L.; Fletcher, Leigh N.

    2014-08-01

    Accurate knowledge of spectroscopic line parameters of PH3 is important for remote sensing of the outer planets, especially Jupiter and Saturn. In a recent study, line positions and intensities for the Pentad bands of PH3 have been reported from analysis of high-resolution, high signal-to noise room-temperature spectra recorded with two Fourier transform spectrometers (2014) [1]. The results presented in this study were obtained during the analysis of positions and intensities, but here we focus on the measurements of spectral line shapes (e.g. widths, shifts, line mixing) for the 2ν4, ν2 + ν4, ν1 and ν3 bands. A multispectrum nonlinear least squares curve fitting technique employing a non-Voigt line shape to include line mixing and speed dependence of the Lorentz width was employed to fit the spectra simultaneously. The least squares fittings were performed on five room-temperature spectra recorded at various PH3 pressures (∼2-50 Torr) with the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington. Over 840 Lorentz self-broadened half-width coefficients, 620 self-shift coefficients and 185 speed dependence parameters were measured. Line mixing was detected for transitions in the 2ν4, ν1 and ν3 bands, and their values were quantified for 10 A+A- pairs of transitions via off-diagonal relaxation matrix element formalism. The dependences of the measured half-width coefficients on the J and K rotational quanta of the transitions are discussed. The self-width coefficients for the ν1 and ν3 bands from this study are compared to the self-width coefficients for transitions with the same rotational quanta (J, K) reported for the Dyad (ν2 and ν4) bands. The measurements from present study should be useful for the development of a reliable theoretical modeling of pressure-broadened widths, shifts and line mixing in symmetric top molecules with C3v symmetry in general, and of PH3

  19. [Research on Adaptive Balance Reaction for Gait Slippery Instability Events on Level Walk Based on Plantar Pressure and Gait Parameter Analysis].

    PubMed

    Li, Yang; Zhang, Junxia; Si, Ying

    2015-12-01

    Nowadays, for gait instability phenomenon, many researches have been carried out at home and abroad. However, the relationship between plantar pressure and gait parameters in the process of balance adjustment is still unclear. This study describes the human body adaptive balance reaction during slip events on slippery level walk by plantar pressure and gait analysis. Ten healthy male subjects walked on a level path wearing shoes with two contrastive contaminants (dry, oil). The study collected and analyzed the change rule of spatiotemporal parameters, plantar pressure parameters, vertical ground reaction force (VGRF), etc. The results showed that the human body adaptive balance reaction during slip events on slippery level walk mainly included lighter touch at the heel strikes, tighter grip at the toe offs, a lower velocity, a shorter stride length and longer support time. These changes are used to maintain or recover body balance. These results would be able to explore new ideas and provide reference value for slip injury prevention, walking rehabilitation training design, research and development of walking assistive equipments, etc. PMID:27079090

  20. MULTISCALE DISCRETIZATION OF SHAPE CONTOURS

    SciTech Connect

    Prasad, L.; Rao, R.

    2000-09-01

    We present an efficient multi-scale scheme to adaptively approximate the continuous (or densely sampled) contour of a planar shape at varying resolutions. The notion of shape is intimately related to the notion of contour, and the efficient representation of the contour of a shape is vital to a computational understanding of the shape. Any polygonal approximation of a planar smooth curve is equivalent to a piecewise constant approximation of the parameterized X and Y coordinate functions of a discrete point set obtained by densely sampling the curve. Using the Haar wavelet transform for the piecewise approximation yields a hierarchical scheme in which the size of the approximating point set is traded off against the morphological accuracy of the approximation. Our algorithm compresses the representation of the initial shape contour to a sparse sequence of points in the plane defining the vertices of the shape's polygonal approximation. Furthermore, it is possible to control the overall resolution of the approximation by a single, scale-independent parameter.

  1. Reliable infrared line lists for 13 CO2 isotopologues up to E‧=18,000 cm-1 and 1500 K, with line shape parameters

    NASA Astrophysics Data System (ADS)

    Huang (黄新川), Xinchuan; Gamache, Robert R.; Freedman, Richard S.; Schwenke, David W.; Lee, Timothy J.

    2014-11-01

    Reliable infrared (IR) line lists are reported for the 13 isotopologues of carbon dioxide in HITRAN notation: 626, 636, 628, 627, 828, 727, 827, 638, 637, 737, 838, 738, and 646. Three IR lists are available for each istotopologue: a complete list at 296 K, a reduced-size list at 296 K, plus a reduced-size list at 1000 K. They are denoted Ames-296K, Ames-296K.reduced and Ames-1000K.reduced. With J up to 150, and energy up to 18,000 cm-1 above the zero point energy, these lists are expected to cover the temperature range up to 1500 K. Line shape parameters including temperature dependence are calculated and reported for four temperature ranges: Mars, Earth, Venus, and Hotter (700-2000 K). Comparisons are made against the available transition data in the HITRAN2012 models. Line position accuracy for most transitions up to 10,000-13,000 cm-1 is better than 0.03-0.05 cm-1. Computed transition intensities agree well with most HITRAN data but there exist suspicious exceptions for isotopologues. These line lists will expedite CO2 IR experimental data analysis and provide the scientific community with trustworthy alternatives for unknown IR bands. These line lists may be combined with existing experimental databases to facilitate the analysis of future laboratory experiments or astronomical observations.

  2. Temperature dependences of self- and N2-broadened line-shape parameters in the ν3 and ν5 bands of 12CH3D: Measurements and calculations

    NASA Astrophysics Data System (ADS)

    Predoi-Cross, A.; Malathy Devi, V.; Sutradhar, P.; Sinyakova, T.; Buldyreva, J.; Sung, K.; Smith, M. A. H.; Mantz, A. W.

    2016-07-01

    This paper presents the results of a spectroscopic line shape study of self- and nitrogen-broadened 12CH3D transitions in the ν3 and ν5 bands in the Triad region. We combined five pure gas spectra with eighteen spectra of lean mixtures of 12CH3D and nitrogen, all recorded with a Bruker IFS-125 HR Fourier transform spectrometer. The spectra have been analyzed simultaneously using a multispectrum nonlinear least squares fitting technique. N2-broadened line parameters for 184 transitions in the ν3 band and 205 transitions in the ν5 band were measured. In addition, line positions and line intensities were measured for 168 transitions in the ν3 band and 214 transitions in the ν5 band. We have observed 10 instances of weak line mixing corresponding to K″=3 A1 or A2 transitions. Comparisons were made for the N2-broadening coefficients and associated temperature exponents with corresponding values calculated using a semi-classical Robert Bonamy type formalism that involved an inter-molecular potential with terms corresponding to short- and long-range interactions, and exact classical molecular trajectories. The theoretical N2-broadened coefficients are overestimated for high J values, but are in good agreement with the experimental values for small and middle range J values.

  3. Self- and air-broadened line shape parameters in the ν2+ν3 band of 12CH4: 4500-4630 cm-1

    NASA Astrophysics Data System (ADS)

    Devi, V. Malathy; Benner, D. Chris; Smith, Mary Ann H.; Mantz, Arlan W.; Sung, Keeyoon; Crawford, Timothy J.; Predoi-Cross, Adriana

    2015-02-01

    Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. In this paper, we report the self- and air-broadened Lorentz half-widths, pressure-induced shifts and line mixing coefficients (via off-diagonal relaxation matrix elements) along with their temperature dependences for methane ν2+ν3 absorption lines in the 4500-4630 cm-1 region of the Octad. For this, we recorded 14 high-resolution, high signal to noise ratio (S/N) spectra of high-purity (99.95% 12C-enriched) samples of pure methane and its dilute mixtures in dry air between 298 K and 148 K. A Bruker IFS 125HR Fourier transform spectrometer (FTS) at the Jet Propulsion Laboratory, Pasadena, California, was used to obtain the experimental data. The absorption cell used for this study was a specially built 20.38 cm long coolable cell installed in its sample compartment. The sample pressures for the pure 12CH4 spectra were 4.5-385 Torr; for the air-broadened spectra the total pressures ranged between 95 and 300 Torr with the methane volume mixing ratios between 0.04 and 0.097. All 14 spectra were fitted simultaneously using an interactive multispectrum nonlinear least-squares curve fitting technique. The results are compared to values reported in the literature.

  4. Design for a region-wide adaptive search for the ivorybilled woodpecker with the objective of estimating occupancy and related parameters

    USGS Publications Warehouse

    Cooper, R.J.; Mordecai, Rua S.; Mattsson, B.G.; Conroy, M.J.; Pacifici, K.; Peterson, J.T.; Moore, C.T.

    2008-01-01

    We describe a survey design and field protocol for the Ivory-billed Woodpecker (Campephilus principalis) search effort that will: (1) allow estimation of occupancy, use, and detection probability for habitats at two spatial scales within the bird?s former range, (2) assess relationships between occupancy, use, and habitat characteristics at those scales, (3) eventually allow the development of a population viability model that depends on patch occupancy instead of difficult-to-measure demographic parameters, and (4) be adaptive, allowing newly collected information to update the above models and search locations. The approach features random selection of patches to be searched from a sampling frame stratified and weighted by patch quality, and requires multiple visits per patch. It is adaptive within a season in that increased search activity is allowed in and around locations of strong visual and/or aural evidence, and adaptive among seasons in that habitat associations allow modification of stratum weights. This statistically rigorous approach is an improvement over simply visiting the ?best? habitat in an ad hoc fashion because we can learn from prior effort and modify the search accordingly. Results from the 2006-07 search season indicate weak relationships between occupancy and habitat (although we suggest modifications of habitat measurement protocols), and a very low detection probability, suggesting more visits per patch are required. Sample size requirements will be discussed.

  5. Fuzzy Sets in Dynamic Adaptation of Parameters of a Bee Colony Optimization for Controlling the Trajectory of an Autonomous Mobile Robot.

    PubMed

    Amador-Angulo, Leticia; Mendoza, Olivia; Castro, Juan R; Rodríguez-Díaz, Antonio; Melin, Patricia; Castillo, Oscar

    2016-01-01

    A hybrid approach composed by different types of fuzzy systems, such as the Type-1 Fuzzy Logic System (T1FLS), Interval Type-2 Fuzzy Logic System (IT2FLS) and Generalized Type-2 Fuzzy Logic System (GT2FLS) for the dynamic adaptation of the alpha and beta parameters of a Bee Colony Optimization (BCO) algorithm is presented. The objective of the work is to focus on the BCO technique to find the optimal distribution of the membership functions in the design of fuzzy controllers. We use BCO specifically for tuning membership functions of the fuzzy controller for trajectory stability in an autonomous mobile robot. We add two types of perturbations in the model for the Generalized Type-2 Fuzzy Logic System to better analyze its behavior under uncertainty and this shows better results when compared to the original BCO. We implemented various performance indices; ITAE, IAE, ISE, ITSE, RMSE and MSE to measure the performance of the controller. The experimental results show better performances using GT2FLS then by IT2FLS and T1FLS in the dynamic adaptation the parameters for the BCO algorithm. PMID:27618062

  6. Online state of charge and model parameters estimation of the LiFePO4 battery in electric vehicles using multiple adaptive forgetting factors recursive least-squares

    NASA Astrophysics Data System (ADS)

    Duong, Van-Huan; Bastawrous, Hany Ayad; Lim, KaiChin; See, Khay Wai; Zhang, Peng; Dou, Shi Xue

    2015-11-01

    This paper deals with the contradiction between simplicity and accuracy of the LiFePO4 battery states estimation in the electric vehicles (EVs) battery management system (BMS). State of charge (SOC) and state of health (SOH) are normally obtained from estimating the open circuit voltage (OCV) and the internal resistance of the equivalent electrical circuit model of the battery, respectively. The difficulties of the parameters estimation arise from their complicated variations and different dynamics which require sophisticated algorithms to simultaneously estimate multiple parameters. This, however, demands heavy computation resources. In this paper, we propose a novel technique which employs a simplified model and multiple adaptive forgetting factors recursive least-squares (MAFF-RLS) estimation to provide capability to accurately capture the real-time variations and the different dynamics of the parameters whilst the simplicity in computation is still retained. The validity of the proposed method is verified through two standard driving cycles, namely Urban Dynamometer Driving Schedule and the New European Driving Cycle. The proposed method yields experimental results that not only estimated the SOC with an absolute error of less than 2.8% but also characterized the battery model parameters accurately.

  7. Adaptive control of the unique mobility EV drive system to account for time-varying battery parameters

    SciTech Connect

    Kopf, C.

    1995-07-01

    Unique Mobility developed an electric vehicle drive system which is being used in the BMW E1. This system is comprised of a permanent magnet brushless DC motor, amplifier, and microprocessor controller. The system is capable of high torque (150 Nm) at low speeds (< 2,000 rpm) and constant power (32 kW) at higher speeds (to 8,000 rpm). The design of the system utilizes a 6 step drive in combination with microprocessor control. The topology of the drive was designed to maximize overall system efficiency. The control system was designed to operate smoothly while transitioning between different regions of operation. The controller must also regulate the torque to stay within all of the safety limits, two of which are under voltage and over voltage. The under voltage limit is used to prevent fully discharging the batteries to prolong their life, and the over voltage limit is necessary to protect the power devices in the amplifier and/or prevent outgassing of the battery. The maximum voltage from the motor in regeneration is a function of the regenerated current, the internal battery impedance in regeneration, and the open circuit bus voltage.the open circuit bus voltage and the internal battery impedance in regeneration varies with each different battery technology, and the batteries` short and long term charge/discharge history. The described drive system adapts to any battery technology by limiting the user to only the maximum instantaneous power that the battery can provide (in motoring) or accept (in regeneration).

  8. 2H nuclear magnetic resonance order parameter profiles suggest a change of molecular shape for phosphatidylcholines containing a polyunsaturated acyl chain.

    PubMed Central

    Holte, L. L.; Peter, S. A.; Sinnwell, T. M.; Gawrisch, K.

    1995-01-01

    Solid-state 2H nuclear magnetic resonance spectroscopy was used to determine the orientational order parameter profiles for a series of phosphatidylcholines with perdeuterated stearic acid, 18:0d35, in position sn-1 and 18:1 omega 9, 18:2 omega 6, 18:3 omega 3, 20:4 omega 6, 20:5 omega 3, or 22:6 omega 3 in position sn-2. The main phase transition temperatures were derived from a first moment analysis, and order parameter profiles of sn-1 chains were calculated from dePaked nuclear magnetic resonance powder patterns. Comparison of the profiles at 37 degrees C showed that unsaturation causes an inhomogenous disordering along the sn-1 chain. Increasing sn-2 chain unsaturation from one to six double bonds resulted in a 1.6-kHz decrease in quadrupolar splittings of the sn-1 chain in the upper half of the chain (or plateau region) and maximum splitting difference of 4.4 kHz at methylene carbon 14. The change in chain order corresponds to a decrease in the 18:0 chain length of 0.4 +/- 0.2 A with 18:2 omega 6 versus 18:1 omega 9 in position sn-2. Fatty acids containing three or more double bonds in sn-2 showed a decrease in sn-1 chain length of 0.7 +/- 0.2 A compared with 18:1 omega 9. The chain length of all lipids decreased with increasing temperature. Highly unsaturated phosphatidylcholines (three or more double bonds in sn-2) had shorter sn-1 chains, but the chain length was somewhat less sensitive to temperature. The profiles reveal that the sn-1 chain exhibits a selective increase in motional freedom in a region located toward the bottom half of the chain as sn-2 unsaturation is increased. This corresponds to an area increase around carbon atom number 14 that is three to four times greater than the increase for the top part of the chain. A similar asymmetric decrease in order, largest toward the methyl end of the chain, was observed when 1 -palmitoyl-2-oleoylphosphatidylethanolamine goes from a lamellar to an inverse hexagonal (H,,) phase. This is consistent with a

  9. Adapting Animals.

    ERIC Educational Resources Information Center

    Wedman, John; Wedman, Judy

    1985-01-01

    The "Animals" program found on the Apple II and IIe system master disk can be adapted for use in the mathematics classroom. Instructions for making the necessary changes and suggestions for using it in lessons related to geometric shapes are provided. (JN)

  10. Adaptive waveguide bends with homogeneous, nonmagnetic, and isotropic materials.

    PubMed

    Han, Tiancheng; Qiu, Cheng-Wei; Tang, Xiaohong

    2011-01-15

    We propose a method for adaptive waveguide bends using homogeneous, nonmagnetic, and isotropic materials, which simplifies the parameters of the bends to the utmost extent. The proposed bend has an adaptive and compact shape because of all the flat boundaries. The nonmagnetic property is realized by selecting OB'/OC = 0.5. Only two nonmagnetic isotropic dielectrics are needed throughout, and the transmission is not sensitive to nonmagnetic isotropic dielectrics. Results validate and illustrate these functionalities, which make the bend much easier to fabricate and apply, owing to its simple parameters, compact shape, and versatility in connecting different waveguides. PMID:21263493

  11. Treatment of Locally Advanced Vaginal Cancer With Radiochemotherapy and Magnetic Resonance Image-Guided Adaptive Brachytherapy: Dose-Volume Parameters and First Clinical Results

    SciTech Connect

    Dimopoulos, Johannes C.A.; Schmid, Maximilian P.; Fidarova, Elena; Berger, Daniel; Kirisits, Christian; Poetter, Richard

    2012-04-01

    Purpose: To investigate the clinical feasibility of magnetic resonance image-guided adaptive brachytherapy (IGABT) for patients with locally advanced vaginal cancer and to report treatment outcomes. Methods and Materials: Thirteen patients with vaginal cancer were treated with external beam radiotherapy (45-50.4 Gy) plus IGABT with or without chemotherapy. Distribution of International Federation of Gynecology and Obstetrics stages among patients were as follows: 4 patients had Stage II cancer, 5 patients had Stage III cancer, and 4 patients had Stage IV cancer. The concept of IGABT as developed for cervix cancer was transferred and adapted for vaginal cancer, with corresponding treatment planning and reporting. Doses were converted to the equivalent dose in 2 Gy, applying the linear quadratic model ({alpha}/{beta} = 10 Gy for tumor; {alpha}/{beta} = 3 for organs at risk). Endpoints studied were gross tumor volume (GTV), dose-volume parameters for high-risk clinical target volume (HRCTV), and organs at risk, local control (LC), adverse side effects, and survival. Results: The mean GTV ({+-} 1 standard deviation) at diagnosis was 45.3 ({+-}30) cm{sup 3}, and the mean GTV at brachytherapy was 10 ({+-}14) cm{sup 3}. The mean D90 for the HRCTV was 86 ({+-}13) Gy. The mean D2cc for bladder, urethra, rectum, and sigmoid colon were 80 ({+-}20) Gy, 76 ({+-}16) Gy, 70 ({+-}9) Gy, and 60 ({+-}9) Gy, respectively. After a median follow-up of 43 months (range, 19-87 months), one local recurrence and two distant metastases cases were observed. Actuarial LC and overall survival rates at 3 years were 92% and 85%. One patient with Stage IVA and 1 patient with Stage III disease experienced fistulas (one vesicovaginal, one rectovaginal), and 1 patient developed periurethral necrosis. Conclusions: The concept of IGABT, originally developed for treating cervix cancer, appears to be applicable to vaginal cancer treatment with only minor adaptations. Dose-volume parameters for HRCTV and

  12. Manipulating cell shape by placing cells into micro-fabricated chambers.

    PubMed

    Chang, Fred; Atilgan, Erdinc; Burgess, David; Minc, Nicolas

    2014-01-01

    Cell shape is an important cellular parameter that influences the spatial organization and function of cells. However, it has often been challenging to study the effects of cell shape because of difficulties in experimentally controlling cell shape in a defined way. We describe here a method of physically manipulating sea urchin cells into specified shapes by inserting them into micro-fabricated chambers of different shapes. This method allows for generation of large systematic and quantitative data sets and may be adaptable for different cell types and contexts. PMID:24633802

  13. Effect of rumen bacteria from sheep adapted to a tanninferous diet on in vitro fermentation parameters of pistachio hulls using bovine inoculum

    PubMed Central

    Babaei, Y; Rouzbehan, Y; Alipour, D

    2015-01-01

    Sheep adapted to consume tannins rich feeds such as oak leaf (OL) appear to develop defensive mechanisms by their ruminal bacteria against these polyphenols. The capabilities of ruminal isolated tannins resistant bacteria from these animals to ferment a tanniniferous feed (i.e., pistachio hulls, (PH) which were incubated with rumen fluid from Holstein dairy cows was assessed. Six g positive cocci were isolated from the rumen of sheep and the 16s rRNA gene sequences showed them to be closely related to Streptococcus gallolyticus. In three runs of in vitro gas production (GP), the effect of two of the isolates incubated with buffered-ruminal fluid of Holstein cow and PH was evaluated. The GP was recorded from 1 to 96 h of incubation. Incubating either of the isolates with PH caused a significantly higher in vitro gas production, estimated parameters, in vitro organic matter disappearance, metabolisable energy and volatile fatty acids than those without any isolate. The improvement in the ruminal parameters when either of the isolates was used suggested the possible presence of isolated tannins-resistant bacteria (Streptococcus gallolyticus sp.), however, in vivo studies must be conducted to confirm the in vitro results. PMID:27175203

  14. Statistics of the sodium layer parameters at low geographic latitude and its impact on adaptive-optics sodium laser guide star characteristics

    NASA Astrophysics Data System (ADS)

    Moussaoui, N.; Clemesha, B. R.; Holzlöhner, R.; Simonich, D. M.; Bonaccini Calia, D.; Hackenberg, W.; Batista, P. P.

    2010-02-01

    Aims: To aid the design of laser guide star (LGS) assisted adaptive optics (AO) systems, we present an analysis of the statistics of the mesospheric sodium layer based on long-term observations (35 years). Methods: We analyze measurements of the Na-layer characteristics covering a long period (1973-2008), acquired at latitude 23degr south, in Stilde{a}o Josacute{e} dos Compos, Stilde{a}o Paulo, Brazil. We note that Paranal (Chile) is located at latitude 24degr south, approximately the same latitude as Stilde{a}o Paulo. Results: This study allowed us to assess the availability of LGS-assisted AO systems depending on the sodium layer properties. We also present an analysis of the LGSs spot elongation over the year, as well as the nocturnal and the seasonal variation in the mesospheric sodium layer parameters. Conclusions: The average values of the sodium layer parameters are 92.09 km for the centroid height, 11.37 km for the layer thickness, and 5×1013 m-2 for the column abundance. Assuming a laser of sufficient power to produce an adequate photon return flux for an AO system with a column abundance of 4× 1013 m-2, a telescope could observe at low geographic latitudes with the sodium LGS more than 250 days per year. Increasing this power by 20%, we could observe throughout the entire year.

  15. Effect of rumen bacteria from sheep adapted to a tanninferous diet on in vitro fermentation parameters of pistachio hulls using bovine inoculum.

    PubMed

    Babaei, Y; Rouzbehan, Y; Alipour, D

    2015-01-01

    Sheep adapted to consume tannins rich feeds such as oak leaf (OL) appear to develop defensive mechanisms by their ruminal bacteria against these polyphenols. The capabilities of ruminal isolated tannins resistant bacteria from these animals to ferment a tanniniferous feed (i.e., pistachio hulls, (PH) which were incubated with rumen fluid from Holstein dairy cows was assessed. Six g positive cocci were isolated from the rumen of sheep and the 16s rRNA gene sequences showed them to be closely related to Streptococcus gallolyticus. In three runs of in vitro gas production (GP), the effect of two of the isolates incubated with buffered-ruminal fluid of Holstein cow and PH was evaluated. The GP was recorded from 1 to 96 h of incubation. Incubating either of the isolates with PH caused a significantly higher in vitro gas production, estimated parameters, in vitro organic matter disappearance, metabolisable energy and volatile fatty acids than those without any isolate. The improvement in the ruminal parameters when either of the isolates was used suggested the possible presence of isolated tannins-resistant bacteria (Streptococcus gallolyticus sp.), however, in vivo studies must be conducted to confirm the in vitro results. PMID:27175203

  16. ProTaper and WaveOne systems three-dimensional comparison of device parameters after the shaping technique. A micro-CT study on simulated root canals

    PubMed Central

    Dioguardi, Mario; Troiano, Giuseppe; Laino, Luigi; Russo, Lucio Lo; Giannatempo, Giovanni; Lauritano, Floriana; Cicciù, Marco; Muzio, Lorenzo Lo

    2015-01-01

    Aim: The aim of this study is to highlights possible differences in the volume of shaping and canal surface area after the using of common endodontic devices ProTaper Universal and WaveOne systems. Methods: Forty ISO 15, 0.02 taper, S-shaped endo-training Blocks (Dentsply, Maillefer) were assigned in two groups (n = 20 for each group). For each block the initial working length (WL) was evaluated with a 10 K-files (Dentsply Maillefer), so the glide path was created with PathFile 1, 2 and 3 (Dentsply Maillefer) at the WL. After that, simulated canals in the group 1 were shaped with S1, S2, F1 and F2 at WL; while in group 2 it was used single-file WaveOne primary in reciprocating motion. After shaping, the resin blocks were analysed with Skyscan 1172 scanner (Skyscan, Kontich, Belgium) and then volumetrically at a source voltage of 65 kV and a source current of 153 uA. Results: No statistically differences (P > 0.05) have been found in terms of volume and surface area after the use of ProTaper Universal and WaveOne systems. Conclusions: Although, results from micro-CT analysis revealed that Wave One result in a decrease of volume and surface area of shaping than ProTaper Universal, differences are not statistically significant. PMID:26770376

  17. Solids with Cracks and Pores of Various Shapes: Proper Parameters of Defect Density, Anisotropy and Extraction of Information on Damage from Wavespeed Patterns. Final Report

    SciTech Connect

    Mark Kachanov

    2000-11-01

    The research under the grant was focused on the micromechanics of with multiple defects of diverse shapes. Within this general area, the problems addressed were quite diverse: Mechanics of electro-elastic materials; Plasticity of porous materials; and Mechanics of materials with multiple defects.

  18. All-optical programmable shaping of narrow-band nanosecond pulses with picosecond accuracy by use of adapted chirps and quadratic nonlinearities.

    PubMed

    Ribeyre, X; Rouyer, C; Raoult, F; Husson, D; Sauteret, C; Migus, A

    2001-08-01

    We experimentally demonstrate pure optical pulse picosecond shaping of narrow-bandwidth nanosecond pulses. The method used is based on the manipulation in the spectral domain of strongly chirped femtosecond pulses and on the use of either frequency addition or frequency difference. PMID:18049553

  19. Adaptive neuro-fuzzy inference system (ANFIS) to predict CI engine parameters fueled with nano-particles additive to diesel fuel

    NASA Astrophysics Data System (ADS)

    Ghanbari, M.; Najafi, G.; Ghobadian, B.; Mamat, R.; Noor, M. M.; Moosavian, A.

    2015-12-01

    This paper studies the use of adaptive neuro-fuzzy inference system (ANFIS) to predict the performance parameters and exhaust emissions of a diesel engine operating on nanodiesel blended fuels. In order to predict the engine parameters, the whole experimental data were randomly divided into training and testing data. For ANFIS modelling, Gaussian curve membership function (gaussmf) and 200 training epochs (iteration) were found to be optimum choices for training process. The results demonstrate that ANFIS is capable of predicting the diesel engine performance and emissions. In the experimental step, Carbon nano tubes (CNT) (40, 80 and 120 ppm) and nano silver particles (40, 80 and 120 ppm) with nanostructure were prepared and added as additive to the diesel fuel. Six cylinders, four-stroke diesel engine was fuelled with these new blended fuels and operated at different engine speeds. Experimental test results indicated the fact that adding nano particles to diesel fuel, increased diesel engine power and torque output. For nano-diesel it was found that the brake specific fuel consumption (bsfc) was decreased compared to the net diesel fuel. The results proved that with increase of nano particles concentrations (from 40 ppm to 120 ppm) in diesel fuel, CO2 emission increased. CO emission in diesel fuel with nano-particles was lower significantly compared to pure diesel fuel. UHC emission with silver nano-diesel blended fuel decreased while with fuels that contains CNT nano particles increased. The trend of NOx emission was inverse compared to the UHC emission. With adding nano particles to the blended fuels, NOx increased compared to the net diesel fuel. The tests revealed that silver & CNT nano particles can be used as additive in diesel fuel to improve combustion of the fuel and reduce the exhaust emissions significantly.

  20. A Load Frequency Control in an Off-Grid Sustainable Power System Based on a Parameter Adaptive PID-Type Fuzzy Controller

    NASA Astrophysics Data System (ADS)

    Ronilaya, Ferdian; Miyauchi, Hajime

    2014-10-01

    This paper presents a new implementation of a parameter adaptive PID-type fuzzy controller (PAPIDfc) for a grid-supporting inverter of battery to alleviate frequency fluctuations in a wind-diesel power system. A variable speed wind turbine that drives a permanent magnet synchronous generator is assumed for demonstrations. The PAPIDfc controller is built from a set of control rules that adopts the droop method and uses only locally measurable frequency signal. The output control signal is determined from the knowledge base and the fuzzy inference. The input-derivative gain and the output-integral gain of the PAPIDfc are tuned online. To ensure safe battery operating limits, we also propose a protection scheme called intelligent battery protection (IBP). Several simulation experiments are performed by using MATLAB®/SimPowersystems™. Next, to verify the scheme's effectiveness, the simulation results are compared with the results of conventional controllers. The results demonstrate the effectiveness of the PAPIDfc scheme to control a grid-supporting inverter of the battery in the reduction of frequency fluctuations.

  1. What lies beneath: sub-articular long bone shape scaling in eutherian mammals and saurischian dinosaurs suggests different locomotor adaptations for gigantism.

    PubMed

    Bonnan, Matthew F; Wilhite, D Ray; Masters, Simon L; Yates, Adam M; Gardner, Christine K; Aguiar, Adam

    2013-01-01

    Eutherian mammals and saurischian dinosaurs both evolved lineages of huge terrestrial herbivores. Although significantly more saurischian dinosaurs were giants than eutherians, the long bones of both taxa scale similarly and suggest that locomotion was dynamically similar. However, articular cartilage is thin in eutherian mammals but thick in saurischian dinosaurs, differences that could have contributed to, or limited, how frequently gigantism evolved. Therefore, we tested the hypothesis that sub-articular bone, which supports the articular cartilage, changes shape in different ways between terrestrial mammals and dinosaurs with increasing size. Our sample consisted of giant mammal and reptile taxa (i.e., elephants, rhinos, sauropods) plus erect and non-erect outgroups with thin and thick articular cartilage. Our results show that eutherian mammal sub-articular shape becomes narrow with well-defined surface features as size increases. In contrast, this region in saurischian dinosaurs expands and remains gently convex with increasing size. Similar trends were observed in non-erect outgroup taxa (monotremes, alligators), showing that the trends we report are posture-independent. These differences support our hypothesis that sub-articular shape scales differently between eutherian mammals and saurischian dinosaurs. Our results show that articular cartilage thickness and sub-articular shape are correlated. In mammals, joints become ever more congruent and thinner with increasing size, whereas archosaur joints remained both congruent and thick, especially in sauropods. We suggest that gigantism occurs less frequently in mammals, in part, because joints composed of thin articular cartilage can only become so congruent before stress cannot be effectively alleviated. In contrast, frequent gigantism in saurischian dinosaurs may be explained, in part, by joints with thick articular cartilage that can deform across large areas with increasing load. PMID:24130690

  2. Towards femtosecond laser surgery guidance in the posterior eye: utilization of optical coherence tomography and adaptive optics for focus positioning and shaping

    NASA Astrophysics Data System (ADS)

    Krüger, Alexander; Hansen, Anja; Matthias, Ben; Ripken, Tammo

    2014-02-01

    Although fs-laser surgery is clinically established in the field of corneal flap cutting for laser in situ keratomileusis, surgery with fs-laser in the posterior part of the eye is impaired by focus degradation due to aberrations. Precise targeting and keeping of safety distance to the retina also relies on an intraoperative depth resolved imaging. We demonstrate a concept for image guided fs-laser surgery in the vitreous body combining adaptive optics (AO) for focus reshaping and optical coherence tomography (OCT) for focus position guidance. The setup of the laboratory system consist of an 800 nm fs-laser which is focused into a simple eye model via a closed loop adaptive optics system with Hartmann-Shack sensor and a deformable mirror to correct for wavefront aberrations. A spectral domain optical coherence tomography system is used to target phantom structures in the eye model. Both systems are set up to share the same scanner and focusing optics. The use of adaptive optics results in a lowered threshold energy for laser induced breakdown and an increased cutting precision. 3D OCT imaging of porcine retinal tissue prior and immediately after fs-laser cutting is also demonstrated. In the near future OCT and AO will be two essential assistive components in possible clinical systems for fs-laser based eye surgery beyond the cornea.

  3. The relative roles of cultural drift and acoustic adaptation in shaping syllable repertoires of island bird populations change with time since colonization.

    PubMed

    Potvin, Dominique A; Clegg, Sonya M

    2015-02-01

    In birds, song divergence often precedes and facilitates divergence of other traits. We assessed the relative roles of cultural drift, innovation, and acoustic adaptation in divergence of island bird dialects, using silvereyes (Zosterops lateralis). In recently colonized populations, syllable diversity was not significantly lower than source populations, shared syllables between populations decreased with increasing number of founder events, and dialect variation displayed contributions from both habitat features and drift. The breadth of multivariate space occupied by recently colonized Z. l. lateralis populations was comparable to evolutionarily old forms that have diverged over thousands to hundreds of thousands of years. In evolutionarily old subspecies, syllable diversity was comparable to the mainland and the amount of variation in syllable composition explained by habitat features increased by two- to threefold compared to recently colonized populations. Together these results suggest that cultural drift influences syllable repertoires in recently colonized populations, but innovation likely counters syllable loss from colonization. In evolutionarily older populations, the influence of acoustic adaptation increases, possibly favoring a high diversity of syllables. These results suggest that the relative importance of cultural drift and acoustic adaptation changes with time since colonization in island bird populations, highlighting the value of considering multiple mechanisms and timescale of divergence when investigating island song divergence. PMID:25496402

  4. Shaping light with MOEMS

    NASA Astrophysics Data System (ADS)

    Noell, W.; Weber, S.; Masson, J.; Extermann, J.; Bonacina, L.; Bich, A.; Bitterli, R.; Herzig, H. P.; Kiselev, D.; Scharf, T.; Voelkel, R.; Weible, K. J.; Wolf, J.-P.; de Rooij, N. F.

    2011-03-01

    Shaping light with microtechnology components has been possible for many years. The Texas Instruments digital micromirror device (DMD) and all types of adaptive optics systems are very sophisticated tools, well established and widely used. Here we present, however, two very dedicated systems, where one is an extremely simple MEMS-based tunable diffuser, while the second device is complex micromirror array with new capabilities for femtosecond laser pulse shaping. Showing the two systems right next to each other demonstrates the vast options and versatility of MOEMS for shaping light in the space and time domain.

  5. Robust, optimal subsonic airfoil shapes

    NASA Technical Reports Server (NTRS)

    Rai, Man Mohan (Inventor)

    2008-01-01

    Method system, and product from application of the method, for design of a subsonic airfoil shape, beginning with an arbitrary initial airfoil shape and incorporating one or more constraints on the airfoil geometric parameters and flow characteristics. The resulting design is robust against variations in airfoil dimensions and local airfoil shape introduced in the airfoil manufacturing process. A perturbation procedure provides a class of airfoil shapes, beginning with an initial airfoil shape.

  6. DISJUNCTIVE NORMAL SHAPE MODELS

    PubMed Central

    Ramesh, Nisha; Mesadi, Fitsum; Cetin, Mujdat; Tasdizen, Tolga

    2016-01-01

    A novel implicit parametric shape model is proposed for segmentation and analysis of medical images. Functions representing the shape of an object can be approximated as a union of N polytopes. Each polytope is obtained by the intersection of M half-spaces. The shape function can be approximated as a disjunction of conjunctions, using the disjunctive normal form. The shape model is initialized using seed points defined by the user. We define a cost function based on the Chan-Vese energy functional. The model is differentiable, hence, gradient based optimization algorithms are used to find the model parameters. PMID:27403233

  7. Simulation of car impact to pedestrian lower extremity: influence of different car-front shapes and dummy parameters on test results.

    PubMed

    Ishikawa, H; Kajzer, J; Ono, K; Sakurai, M

    1994-04-01

    Sled impact tests on mechanical substitutes for a pedestrian were conducted as a preliminary study for the purpose of developing a subsystem test procedure for the assessment of car-front aggressiveness to pedestrian legs. Four mechanical substitutes for a pedestrian were used in the test: the leg of a rotationally symmetrical pedestrian dummy (RSPD) as the representation of a subsystem, a HYBRID-II pedestrian dummy, a modified HYBRID-II pedestrian dummy equipped with a steel bar serving as knee joint, and a RSPD - HYBRID-IIP combined dummy in which the lower part of the RSPD and the upper part of the HYBRID-IIP were connected by a joint in such a way that the movements of the upper part were similar to those in cadaver tests. In the tests the following were evaluated: (i) the influence of vehicle shape on knee response and on vehicle impact force; (ii) the influence of the upper body mass on knee response and on vehicle impact forces; (iii) the influence of the bumper system on knee response, the kinematics of pedestrian mechanical substitute, and on vehicle impact forces; (iv) the influence of pedestrian mechanical substitute characteristics on its kinematics and knee response, and on vehicle impact forces. This paper describes a primary concept when subsystem test methods for the assessment of car-front aggressiveness to pedestrian legs in a car-pedestrian collision are considered. PMID:8198692

  8. Shape memory polymer actuator and catheter

    DOEpatents

    Maitland, Duncan J.; Lee, Abraham P.; Schumann, Daniel L.; Matthews, Dennis L.; Decker, Derek E.; Jungreis, Charles A.

    2007-11-06

    An actuator system is provided for acting upon a material in a vessel. The system includes an optical fiber and a shape memory polymer material operatively connected to the optical fiber. The shape memory polymer material is adapted to move from a first shape for moving through said vessel to a second shape where it can act upon said material.

  9. Shape memory polymer actuator and catheter

    DOEpatents

    Maitland, Duncan J.; Lee, Abraham P.; Schumann, Daniel L.; Matthews, Dennis L.; Decker, Derek E.; Jungreis, Charles A.

    2004-05-25

    An actuator system is provided for acting upon a material in a vessel. The system includes an optical fiber and a shape memory polymer material operatively connected to the optical fiber. The shape memory polymer material is adapted to move from a first shape for moving through said vessel to a second shape where it can act upon said material.

  10. Rocketing into Adaptive Inquiry.

    ERIC Educational Resources Information Center

    Farenga, Stephen J.; Joyce, Beverly A.; Dowling, Thomas W.

    2002-01-01

    Defines adaptive inquiry and argues for employing this method which allows lessons to be shaped in response to student needs. Illustrates this idea by detailing an activity in which teams of students build rockets. (DDR)

  11. P. falciparum Infection Durations and Infectiousness Are Shaped by Antigenic Variation and Innate and Adaptive Host Immunity in a Mathematical Model

    PubMed Central

    Eckhoff, Philip

    2012-01-01

    Many questions remain about P. falciparum within-host dynamics, immunity, and transmission–issues that may affect public health campaign planning. These gaps in knowledge concern the distribution of durations of malaria infections, determination of peak parasitemia during acute infection, the relationships among gametocytes and immune responses and infectiousness to mosquitoes, and the effect of antigenic structure on reinfection outcomes. The present model of intra-host dynamics of P. falciparum implements detailed representations of parasite and immune dynamics, with structures based on minimal extrapolations from first-principles biology in its foundations. The model is designed to quickly and readily accommodate gains in mechanistic understanding and to evaluate effects of alternative biological hypothesis through in silico experiments. Simulations follow the parasite from the liver-stage through the detailed asexual cycle to clearance while tracking gametocyte populations. The modeled immune system includes innate inflammatory and specific antibody responses to a repertoire of antigens. The mechanistic focus provides clear explanations for the structure of the distribution of infection durations through the interaction of antigenic variation and innate and adaptive immunity. Infectiousness to mosquitoes appears to be determined not only by the density of gametocytes but also by the level of inflammatory cytokines, which harmonizes an extensive series of study results. Finally, pre-existing immunity can either decrease or increase the duration of infections upon reinfection, depending on the degree of overlap in antigenic repertoires and the strength of the pre-existing immunity. PMID:23028698

  12. Midpoint Shapes.

    ERIC Educational Resources Information Center

    Welchman, Rosamond; Urso, Josephine

    2000-01-01

    Emphasizes the importance of children exploring hands-on and minds-on mathematics. Presents a midpoint shape activity for students to explore the midpoint shape of familiar quadrilaterals, such as squares and rectangles. (KHR)

  13. Adaptive Femtosecond Quantum Control

    NASA Astrophysics Data System (ADS)

    Gerber, Gustav

    2003-03-01

    Obtaining active control over the dynamics of quantum-mechanical systems is a fascinating perspective in modern physics. A promising tool for this purpose is available with femtosecond laser technologies. The intrinsically broad spectral distribution and the phase function of femtosecond laser pulses can be specifically manipulated by pulse shapers to drive molecular systems coherently into the desired reaction pathways [1]. The approach of adaptive femtosecond quantum control follows the suggestion of Judson and Rabitz [2], in which a computer-controlled pulse shaper is used in combination with a learning algorithm [3] and direct feedback from the experiment to achieve coherent control over quantum-mechanical processes in an automated fashion, without requiring any model for the system's response. This technique can be applied to the control of gas-phase photodissociation processes [4]. Different bond-cleaving reactions can be preferentially selected, resulting in chemically different products. Prior knowledge about molecular Hamiltonians or reaction mechanisms is not required in this automated control loop, and this scheme works for complex systems. Adaptive pulse-shaping techniques can be transferred to the control of photoprocesses in the liquid phase as well, motivated by the wish to achieve control at particle densities high enough for (bimolecular) synthetic-chemical applications. Chemically selective molecular excitation is achieved by many-parameter adaptive quantum control [5], despite the failure of typical single-parameter approaches (such as wavelength control, intensity control, or linear chirp control). This experiment demonstrates that photoprocesses in two different molecular species can be controlled simultaneously. Applications are envisioned in bimolecular reaction control where specific educt molecules could selectively be "activated" for purposes of chemical synthesis. A new technological development further increases the possibilities and

  14. The exchangeability of shape

    PubMed Central

    2010-01-01

    Background Landmark based geometric morphometrics (GM) allows the quantitative comparison of organismal shapes. When applied to systematics, it is able to score shape changes which often are undetectable by traditional morphological studies and even by classical morphometric approaches. It has thus become a fast and low cost candidate to identify cryptic species. Due to inherent mathematical properties, shape variables derived from one set of coordinates cannot be compared with shape variables derived from another set. Raw coordinates which produce these shape variables could be used for data exchange, however they contain measurement error. The latter may represent a significant obstacle when the objective is to distinguish very similar species. Results We show here that a single user derived dataset produces much less classification error than a multiple one. The question then becomes how to circumvent the lack of exchangeability of shape variables while preserving a single user dataset. A solution to this question could lead to the creation of a relatively fast and inexpensive systematic tool adapted for the recognition of cryptic species. Conclusions To preserve both exchangeability of shape and a single user derived dataset, our suggestion is to create a free access bank of reference images from which one can produce raw coordinates and use them for comparison with external specimens. Thus, we propose an alternative geometric descriptive system that separates 2-D data gathering and analyzes. PMID:20964872

  15. Alpha shapes applied to molecular shape characterization exhibit novel properties compared to established shape descriptors

    PubMed Central

    Wilson, J. Anthony; Bender, Andreas; Kaya, Taner; Clemons, Paul A.

    2011-01-01

    Despite considerable efforts, description of molecular shape is still largely an unresolved problem. Given the importance of molecular shape in the description of spatial interactions in crystals or ligand-target complexes, this is not a satisfying state. In the current work, we propose a novel application of alpha shapes to the description of the shapes of small molecules. Alpha shapes are parameterized generalizations of the convex hull. For a specific value of α, the alpha shape is the geometric dual of the space-filling model of a molecule, with the parameter α allowing description of shape in varying degrees of detail. To date, alpha shapes have been used to find macromolecular cavities and to estimate molecular surface areas and volumes. We developed a novel methodology for computing molecular shape characteristics from the alpha shape. In this work, we show that alpha-shape descriptors reveal aspects of molecular shape that are complementary to other shape descriptors, and that accord well with chemists’ intuition about shape. While our implementation of alpha-shape descriptors is not computationally trivial, we suggest that the additional shape characteristics they provide can be used to improve and complement shape-analysis methods in domains such as crystallography and ligand-target interactions. In this communication, we present a unique methodology for computing molecular shape characteristics from the alpha shape. We first describe details of the alpha-shape calculation, an outline of validation experiments performed, and a discussion of the advantages and challenges we found while implementing this approach. The results show that, relative to known shape calculations, this method provides a high degree of shape resolution with even small changes in atomic coordinates. PMID:19775113

  16. Estimating patient specific uncertainty parameters for adaptive treatment re-planning in proton therapy using in vivo range measurements and Bayesian inference: application to setup and stopping power errors.

    PubMed

    Labarbe, Rudi; Janssens, Guillaume; Sterpin, Edmond

    2016-09-01

    In proton therapy, quantification of the proton range uncertainty is important to achieve dose distribution compliance. The promising accuracy of prompt gamma imaging (PGI) suggests the development of a mathematical framework using the range measurements to convert population based estimates of uncertainties into patient specific estimates with the purpose of plan adaptation. We present here such framework using Bayesian inference. The sources of uncertainty were modeled by three parameters: setup bias m, random setup precision r and water equivalent path length bias u. The evolution of the expectation values E(m), E(r) and E(u) during the treatment was simulated. The expectation values converged towards the true simulation parameters after 5 and 10 fractions, for E(m) and E(u), respectively. E(r) settle on a constant value slightly lower than the true value after 10 fractions. In conclusion, the simulation showed that there is enough information in the frequency distribution of the range errors measured by PGI to estimate the expectation values and the confidence interval of the model parameters by Bayesian inference. The updated model parameters were used to compute patient specific lateral and local distal margins for adaptive re-planning. PMID:27494118

  17. Estimating patient specific uncertainty parameters for adaptive treatment re-planning in proton therapy using in vivo range measurements and Bayesian inference: application to setup and stopping power errors

    NASA Astrophysics Data System (ADS)

    Labarbe, Rudi; Janssens, Guillaume; Sterpin, Edmond

    2016-09-01

    In proton therapy, quantification of the proton range uncertainty is important to achieve dose distribution compliance. The promising accuracy of prompt gamma imaging (PGI) suggests the development of a mathematical framework using the range measurements to convert population based estimates of uncertainties into patient specific estimates with the purpose of plan adaptation. We present here such framework using Bayesian inference. The sources of uncertainty were modeled by three parameters: setup bias m, random setup precision r and water equivalent path length bias u. The evolution of the expectation values E(m), E(r) and E(u) during the treatment was simulated. The expectation values converged towards the true simulation parameters after 5 and 10 fractions, for E(m) and E(u), respectively. E(r) settle on a constant value slightly lower than the true value after 10 fractions. In conclusion, the simulation showed that there is enough information in the frequency distribution of the range errors measured by PGI to estimate the expectation values and the confidence interval of the model parameters by Bayesian inference. The updated model parameters were used to compute patient specific lateral and local distal margins for adaptive re-planning.

  18. Schapiro Shapes

    ERIC Educational Resources Information Center

    O'Connell, Emily

    2009-01-01

    This article describes a lesson on Schapiro Shapes. Schapiro Shapes is based on the art of Miriam Schapiro, who created a number of works of figures in action. Using the basic concepts of this project, students learn to create their own figures and styles. (Contains 1 online resource.)

  19. Shape remodeling and blebbing of active cytoskeletal vesicles

    PubMed Central

    Loiseau, Etienne; Schneider, Jochen A. M.; Keber, Felix C.; Pelzl, Carina; Massiera, Gladys; Salbreux, Guillaume; Bausch, Andreas R.

    2016-01-01

    Morphological transformations of living cells, such as shape adaptation to external stimuli, blebbing, invagination, or tethering, result from an intricate interplay between the plasma membrane and its underlying cytoskeleton, where molecular motors generate forces. Cellular complexity defies a clear identification of the competing processes that lead to such a rich phenomenology. In a synthetic biology approach, designing a cell-like model assembled from a minimal set of purified building blocks would allow the control of all relevant parameters. We reconstruct actomyosin vesicles in which the coupling of the cytoskeleton to the membrane, the topology of the cytoskeletal network, and the contractile activity can all be precisely controlled and tuned. We demonstrate that tension generation of an encapsulated active actomyosin network suffices for global shape transformation of cell-sized lipid vesicles, which are reminiscent of morphological adaptations in living cells. The observed polymorphism of our cell-like model, such as blebbing, tether extrusion, or faceted shapes, can be qualitatively explained by the protein concentration dependencies and a force balance, taking into account the membrane tension, the density of anchoring points between the membrane and the actin network, and the forces exerted by molecular motors in the actin network. The identification of the physical mechanisms for shape transformations of active cytoskeletal vesicles sets a conceptual and quantitative benchmark for the further exploration of the adaptation mechanisms of cells. PMID:27152328

  20. Shape remodeling and blebbing of active cytoskeletal vesicles.

    PubMed

    Loiseau, Etienne; Schneider, Jochen A M; Keber, Felix C; Pelzl, Carina; Massiera, Gladys; Salbreux, Guillaume; Bausch, Andreas R

    2016-04-01

    Morphological transformations of living cells, such as shape adaptation to external stimuli, blebbing, invagination, or tethering, result from an intricate interplay between the plasma membrane and its underlying cytoskeleton, where molecular motors generate forces. Cellular complexity defies a clear identification of the competing processes that lead to such a rich phenomenology. In a synthetic biology approach, designing a cell-like model assembled from a minimal set of purified building blocks would allow the control of all relevant parameters. We reconstruct actomyosin vesicles in which the coupling of the cytoskeleton to the membrane, the topology of the cytoskeletal network, and the contractile activity can all be precisely controlled and tuned. We demonstrate that tension generation of an encapsulated active actomyosin network suffices for global shape transformation of cell-sized lipid vesicles, which are reminiscent of morphological adaptations in living cells. The observed polymorphism of our cell-like model, such as blebbing, tether extrusion, or faceted shapes, can be qualitatively explained by the protein concentration dependencies and a force balance, taking into account the membrane tension, the density of anchoring points between the membrane and the actin network, and the forces exerted by molecular motors in the actin network. The identification of the physical mechanisms for shape transformations of active cytoskeletal vesicles sets a conceptual and quantitative benchmark for the further exploration of the adaptation mechanisms of cells. PMID:27152328

  1. CXTFIT/Excel-A modular adaptable code for parameter estimation, sensitivity analysis and uncertainty analysis for laboratory or field tracer experiments

    NASA Astrophysics Data System (ADS)

    Tang, Guoping; Mayes, Melanie A.; Parker, Jack C.; Jardine, Philip M.

    2010-09-01

    We implemented the widely used CXTFIT code in Excel to provide flexibility and added sensitivity and uncertainty analysis functions to improve transport parameter estimation and to facilitate model discrimination for multi-tracer experiments on structured soils. Analytical solutions for one-dimensional equilibrium and nonequilibrium convection dispersion equations were coded as VBA functions so that they could be used as ordinary math functions in Excel for forward predictions. Macros with user-friendly interfaces were developed for optimization, sensitivity analysis, uncertainty analysis, error propagation, response surface calculation, and Monte Carlo analysis. As a result, any parameter with transformations (e.g., dimensionless, log-transformed, species-dependent reactions, etc.) could be estimated with uncertainty and sensitivity quantification for multiple tracer data at multiple locations and times. Prior information and observation errors could be incorporated into the weighted nonlinear least squares method with a penalty function. Users are able to change selected parameter values and view the results via embedded graphics, resulting in a flexible tool applicable to modeling transport processes and to teaching students about parameter estimation. The code was verified by comparing to a number of benchmarks with CXTFIT 2.0. It was applied to improve parameter estimation for four typical tracer experiment data sets in the literature using multi-model evaluation and comparison. Additional examples were included to illustrate the flexibilities and advantages of CXTFIT/Excel. The VBA macros were designed for general purpose and could be used for any parameter estimation/model calibration when the forward solution is implemented in Excel. A step-by-step tutorial, example Excel files and the code are provided as supplemental material.

  2. Asteroid shape modelling with ADAM

    NASA Astrophysics Data System (ADS)

    Viikinkoski, Matti; Kaasalainen, Mikko; Durech, Josef

    2015-08-01

    Technological advancements have made it possible to obtain highly detailed images of asteroids, yet 3-D shape reconstruction remains a challenge. Shape inversion is an ill-posed inverse problem as systematic errors, shadowing effects due to non-convex features, and the limitations of the imaging systems render the direct inversion impossible. Moreover, the coverage of one observation session alone is seldom sufficient for 3-D reconstruction, necessitating a method for the integration of widely different, complementary data sources into a coherent shape solution.We present a new 3-D shape reconstruction method for asteroid models. ADAM, an acronym for all-data asteroid modelling, is a general procedure for combining disk-resolved observational data into a shape model. ADAM handles all disk-resolved data in a uniform manner via 2-D Fourier Transform. Almost all disk-resolved data sources are supported: adaptive optics and other images, range-Doppler radar data, and thermal infrared interferometry.As case studies, we examine the shape of (41) Daphne using the adaptive optics images and photometry, and create a model of the asteroid 2000 ET70 from the range-Doppler radar images. Finally, we combine ALMA science verification data, adaptive optics images, occultations, and lightcurve data to study the shape of the large main-belt asteroid (3) Juno.

  3. Parameters of hormonal regulation of fluid-electrolyte exchange and camp reception in the rat renal papilla during adaptation to cold

    SciTech Connect

    Selyatitskaya, V.G.; Ivanova, L.N.; Shorin, Y.P.; Solenov, E.I.

    1986-03-01

    The authors study the intracellular reaction of cAMP, which is an important functional component of the action of antidiuretic hormone (ADH) in target tissues, in the renal papilla. The aldosterone concentration of the rats' urine was determined by radioimmunoassay. The experiments showed that specific binding of /sup 3/H-cAMP in the cytosol of the renal papilla in animals adapted to cold was 3.2 +/- 0.6 femtomoles/kg protein. A decrease in the concentration of hormones participating in the regulation of fluid-electrolyte exchange was discovered in these experiments. A significant fall in the ADH concentration was observed in the blood plasma of the experimental animals.

  4. Is the solvation parameter model or its adaptations adequate to account for ionic interactions when characterizing stationary phases for drug impurity profiling with supercritical fluid chromatography?

    PubMed

    Galea, Charlene; West, Caroline; Mangelings, Debby; Vander Heyden, Yvan

    2016-06-14

    Nine commercially available polar and aromatic stationary phases were characterized under supercritical fluid chromatographic (SFC) conditions. Retention data of 64 pharmaceutical compounds was acquired to generate models based on the linear solvation energy relationship (LSER) approach. Previously, adaptation of the LSER model was done in liquid chromatography by the addition of two solute descriptors to describe the influence of positive (D(+)) and negative (D(-)) charges on the retention of ionized compounds. In this study, the LSER models, with and without the ionization terms for acidic and basic solutes, were compared. The improved fits obtained for the modified models support inclusion of the D(+) and D(-) terms for pharmaceutical compounds. Moreover, the statistical significance of the new terms in the models indicates the importance of ionic interactions in the retention of pharmaceutical compounds in SFC. However, unlike characterization through the retention profiles, characterization of the stationary phases by modelling never explains the retention variance completely and thus seems less appropriate. PMID:27181639

  5. Line shape parameters of PH3 transitions in the Pentad near 4–5 μm: Self-broadened widths, shifts, line mixing and speed dependence

    SciTech Connect

    Malathy Devi, V.; Benner, D. C.; Kleiner, Isabelle; Sams, Robert L.; Fletcher, Leigh N.

    2014-08-01

    Accurate knowledge of spectroscopic line parameters of PH3 is important for remote sensing of the outer planets, especially Jupiter and Saturn. In a recent study, line positions and intensities for the Pentad bands of PH3 have been reported from analysis of high-resolution, high signal-to noise room-temperature spectra recorded with two Fourier transform spectrometers (2014) [1]. The results presented in this study were obtained during the analysis of positions and intensities, but here we focus on the measurements of spectral line shapes (e.g. widths, shifts, line mixing) for the 2ν4, ν2 + ν4, ν1 and ν3 bands. A multispectrum nonlinear least squares curve fitting technique employing a non-Voigt line shape to include line mixing and speed dependence of the Lorentz width was employed to fit the spectra simultaneously. The least squares fittings were performed on five room-temperature spectra recorded at various PH3 pressures (~2–50 Torr) with the Bruker IFS-125HR Fourier transform spectrometer (FTS) located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington. Over 840 Lorentz self-broadened half-width coefficients, 620 self-shift coefficients and 185 speed dependence parameters were measured. Line mixing was detected for transitions in the 2ν4, ν1 and ν3 bands, and their values were quantified for 10 A+A- pairs of transitions via off-diagonal relaxation matrix element formalism. The dependences of the measured half-width coefficients on the J and K rotational quanta of the transitions are discussed. The self-width coefficients for the ν1 and ν3 bands from this study are compared to the self-width coefficients for transitions with the same rotational quanta (J, K) reported for the Dyad (ν2 and ν4) bands. The measurements from present study should be useful for the

  6. Adaptation of the pseudo-metal-oxide-semiconductor field effect transistor technique to ultrathin silicon-on-insulator wafers characterization: Improved set-up, measurement procedure, parameter extraction, and modeling

    NASA Astrophysics Data System (ADS)

    Van Den Daele, W.; Malaquin, C.; Baumel, N.; Kononchuk, O.; Cristoloveanu, S.

    2013-10-01

    This paper revisits and adapts of the pseudo-MOSFET (Ψ-MOSFET) characterization technique for advanced fully depleted silicon on insulator (FDSOI) wafers. We review the current challenges for standard Ψ-MOSFET set-up on ultra-thin body (12 nm) over ultra-thin buried oxide (25 nm BOX) and propose a novel set-up enabling the technique on FDSOI structures. This novel configuration embeds 4 probes with large tip radius (100-200 μm) and low pressure to avoid oxide damage. Compared with previous 4-point probe measurements, we introduce a simplified and faster methodology together with an adapted Y-function. The models for parameters extraction are revisited and calibrated through systematic measurements of SOI wafers with variable film thickness. We propose an in-depth analysis of the FDSOI structure through comparison of experimental data, TCAD (Technology Computed Aided Design) simulations, and analytical modeling. TCAD simulations are used to unify previously reported thickness-dependent analytical models by analyzing the BOX/substrate potential and the electrical field in ultrathin films. Our updated analytical models are used to explain the results and to extract correct electrical parameters such as low-field electron and hole mobility, subthreshold slope, and film/BOX interface traps density.

  7. An adaptive learning control system for large flexible structures

    NASA Technical Reports Server (NTRS)

    Thau, F. E.

    1985-01-01

    The objective of the research has been to study the design of adaptive/learning control systems for the control of large flexible structures. In the first activity an adaptive/learning control methodology for flexible space structures was investigated. The approach was based on using a modal model of the flexible structure dynamics and an output-error identification scheme to identify modal parameters. In the second activity, a least-squares identification scheme was proposed for estimating both modal parameters and modal-to-actuator and modal-to-sensor shape functions. The technique was applied to experimental data obtained from the NASA Langley beam experiment. In the third activity, a separable nonlinear least-squares approach was developed for estimating the number of excited modes, shape functions, modal parameters, and modal amplitude and velocity time functions for a flexible structure. In the final research activity, a dual-adaptive control strategy was developed for regulating the modal dynamics and identifying modal parameters of a flexible structure. A min-max approach was used for finding an input to provide modal parameter identification while not exceeding reasonable bounds on modal displacement.

  8. Adaptation of short-term plasticity parameters via error-driven learning may explain the correlation between activity-dependent synaptic properties, connectivity motifs and target specificity

    PubMed Central

    Esposito, Umberto; Giugliano, Michele; Vasilaki, Eleni

    2015-01-01

    The anatomical connectivity among neurons has been experimentally found to be largely non-random across brain areas. This means that certain connectivity motifs occur at a higher frequency than would be expected by chance. Of particular interest, short-term synaptic plasticity properties were found to colocalize with specific motifs: an over-expression of bidirectional motifs has been found in neuronal pairs where short-term facilitation dominates synaptic transmission among the neurons, whereas an over-expression of unidirectional motifs has been observed in neuronal pairs where short-term depression dominates. In previous work we found that, given a network with fixed short-term properties, the interaction between short- and long-term plasticity of synaptic transmission is sufficient for the emergence of specific motifs. Here, we introduce an error-driven learning mechanism for short-term plasticity that may explain how such observed correspondences develop from randomly initialized dynamic synapses. By allowing synapses to change their properties, neurons are able to adapt their own activity depending on an error signal. This results in more rich dynamics and also, provided that the learning mechanism is target-specific, leads to specialized groups of synapses projecting onto functionally different targets, qualitatively replicating the experimental results of Wang and collaborators. PMID:25688203

  9. Universality of fragment shapes.

    PubMed

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-01-01

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism. PMID:25772300

  10. Universality of fragment shapes

    PubMed Central

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-01-01

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism. PMID:25772300

  11. Universality of fragment shapes

    NASA Astrophysics Data System (ADS)

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-03-01

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism.

  12. Method For Model-Reference Adaptive Control

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun

    1990-01-01

    Relatively simple method of model-reference adaptive control (MRAC) developed from two prior classes of MRAC techniques: signal-synthesis method and parameter-adaption method. Incorporated into unified theory, which yields more general adaptation scheme.

  13. Adaptive wavelets for visual object detection and classification

    NASA Astrophysics Data System (ADS)

    Aghdasi, Farzin

    1997-10-01

    We investigate the application of adaptive wavelets for the representation and classification of signals in digitized speech and medical images. A class of wavelet basis functions are used to extract features from the regions of interest. These features are then used in an artificial neural network to classify the region are containing the desired object or belonging to the background clutter. The dilation and shift parameters of the wavelet functions are not fixed. These parameters are included in the training scheme. In this way the wavelets are adaptive to the expected shape and size of the signals. The results indicate that adaptive wavelet functions may outperform the classical fixed wavelet analysis in detection of subtle objects.

  14. Low-mass Galaxy Formation in Cosmological Adaptive Mesh Refinement Simulations: The Effects of Varying the Sub-grid Physics Parameters

    NASA Astrophysics Data System (ADS)

    Colín, Pedro; Avila-Reese, Vladimir; Vázquez-Semadeni, Enrique; Valenzuela, Octavio; Ceverino, Daniel

    2010-04-01

    We present numerical simulations aimed at exploring the effects of varying the sub-grid physics parameters on the evolution and the properties of the galaxy formed in a low-mass dark matter halo (~7 × 1010 h -1 M sun at redshift z = 0). The simulations are run within a cosmological setting with a nominal resolution of 218 pc comoving and are stopped at z = 0.43. For simulations that cannot resolve individual molecular clouds, we propose the criterion that the threshold density for star formation, n SF, should be chosen such that the column density of the star-forming cells equals the threshold value for molecule formation, N ~ 1021 cm-2, or ~8 M sun pc-2. In all of our simulations, an extended old/intermediate-age stellar halo and a more compact younger stellar disk are formed, and in most cases, the halo's specific angular momentum is slightly larger than that of the galaxy, and sensitive to the SF/feedback parameters. We found that a non-negligible fraction of the halo stars are formed in situ in a spheroidal distribution. Changes in the sub-grid physics parameters affect significantly and in a complex way the evolution and properties of the galaxy: (1) lower threshold densities n SF produce larger stellar effective radii Re , less peaked circular velocity curves Vc (R), and greater amounts of low-density and hot gas in the disk mid-plane; (2) when stellar feedback is modeled by temporarily switching off radiative cooling in the star-forming regions, Re increases (by a factor of ~2 in our particular model), the circular velocity curve becomes flatter, and a complex multi-phase gaseous disk structure develops; (3) a more efficient local conversion of gas mass to stars, measured by a stellar particle mass distribution biased toward larger values, increases the strength of the feedback energy injection—driving outflows and inducing burstier SF histories; (4) if feedback is too strong, gas loss by galactic outflows—which are easier to produce in low

  15. Primary adaptive mirrors for ELTs: a report on preliminary studies

    NASA Astrophysics Data System (ADS)

    Riccardi, Armando; Del Vecchio, Ciro; Salinari, Piero; Brusa, Guido; Lardiere, Olivier; Gallieni, Daniele; Biasi, Roberto; Mantegazza, Paolo

    2004-07-01

    At the moment the best bet to obtain an extremely high actuator density for extremely large pupils seems to be that of extending the current adaptive secondary mirror technology to segmented "adaptive primaries." The main components of a segment of an adaptive primary mirror are beng studied in order to determine all the parameters able to statically keep the mechanical response within the optical specifications and to dynamically provide the stiffness and damping features needed by the adaptive optics control system. Both static and dynamical requirements depend critically on actuator geometry and structure, mirror shape and thickness, and implementation of the control system. The mechanical response has been numerically evaluated in terms of deformation under gravity, mirror influence functions and actuator layout, including their interface to the shell.

  16. Shape Reconstruction from Generalized Projections

    NASA Astrophysics Data System (ADS)

    Viikinkoski, Matti

    2016-01-01

    In this thesis we develop methods for recovering the three-dimensional shape of an object from generalized projections. We particularly focus on the problems encountered when data are presented as discrete image fields. We demonstrate the usefulness of the Fourier transform in transferring the image data and shape model projections to a domain more suitable for gradient based optimization. To substantiate the general applicability of our methods to observational astronomy, we reconstruct shape models for several asteroids observed with adaptive optics, thermal infrared interferometry, or range-Doppler radar. The reconstructions are carried out with the ADAM software package that we have designed for general use.

  17. Laser fusion pulse shape controller

    DOEpatents

    Siebert, Larry D.

    1977-01-01

    An apparatus for controlling the pulse shape, i.e., the pulse duration and intensity pattern, of a pulsed laser system, and which is particularly well adapted for controlling the pellet ignition pulse in a laser-driven fusion reaction system. The apparatus comprises a laser generator for providing an optical control pulse of the shape desired, a pulsed laser triggered by the control pulse, and a plurality of optical Kerr-effect gates serially disposed at the output of the pulsed laser and selectively triggered by the control pulse to pass only a portion of the pulsed laser output generally corresponding in shape to the control pulse.

  18. Phase Adaptation and Correction by Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Tiziani, Hans J.

    2010-04-01

    Adaptive optical elements and systems for imaging or laser beam propagation are used for some time in particular in astronomy, where the image quality is degraded by atmospheric turbulence. In astronomical telescopes a deformable mirror is frequently used to compensate wavefront-errors due to deformations of the large mirror, vibrations as well as turbulence and hence to increase the image quality. In the last few years interesting elements like Spatial Light Modulators, SLM's, such as photorefractive crystals, liquid crystals and micro mirrors and membrane mirrors were introduced. The development of liquid crystals and micro mirrors was driven by data projectors as consumer products. They contain typically a matrix of individually addressable pixels of liquid crystals and flip mirrors respectively or more recently piston mirrors for special applications. Pixel sizes are in the order of a few microns and therefore also appropriate as active diffractive elements in digital holography or miniature masks. Although liquid crystals are mainly optimized for intensity modulation; they can be used for phase modulation. Adaptive optics is a technology for beam shaping and wavefront adaptation. The application of spatial light modulators for wavefront adaptation and correction and defect analysis as well as sensing will be discussed. Dynamic digital holograms are generated with liquid crystal devices (LCD) and used for wavefront correction as well as for beam shaping and phase manipulation, for instance. Furthermore, adaptive optics is very useful to extend the measuring range of wavefront sensors and for the wavefront adaptation in order to measure and compare the shape of high precision aspherical surfaces.

  19. Decentralized adaptive control

    NASA Technical Reports Server (NTRS)

    Oh, B. J.; Jamshidi, M.; Seraji, H.

    1988-01-01

    A decentralized adaptive control is proposed to stabilize and track the nonlinear, interconnected subsystems with unknown parameters. The adaptation of the controller gain is derived by using model reference adaptive control theory based on Lyapunov's direct method. The adaptive gains consist of sigma, proportional, and integral combination of the measured and reference values of the corresponding subsystem. The proposed control is applied to the joint control of a two-link robot manipulator, and the performance in computer simulation corresponds with what is expected in theoretical development.

  20. Thermal resistance parameters of acid-adapted and unadapted Escherichia coli O157:H7 in apple-carrot juice blends: effect of organic acids and pH.

    PubMed

    Usaga, Jessie; Worobo, Randy W; Padilla-Zakour, Olga I

    2014-04-01

    Numerous outbreaks involving fresh juices contaminated with Escherichia coli O157:H7 have occurred in the United States and around the world, raising concern for the safety of these products. Until now, only a few studies regarding the thermal tolerance of this pathogen in acidic juices over a wide range of pH values have been published. Therefore, the effect of varying the pH with different organic acids on the thermal inactivation of non-acid-adapted and acid-adapted E. coli O157:H7 (strain C7927) was determined. The decimal reduction times (D-values) and the change in temperature required for the thermal destruction curve to traverse 1 log cycle (z-values) were calculated for non-acid-adapted E. coli in an apple-carrot juice blend (80:20) adjusted to three pH values (3.3, 3.5, and 3.7) by the addition of lactic, malic, or acetic acid and at a pH of 4.5 adjusted with NaOH. Thermal parameters were also determined for acid-adapted cells in juices acidified with malic acid. The effect of the soluble solids content on the thermal tolerance was studied in samples with a pH of 3.7 at 9.4 to 11.5 °Brix. The D-values were determined at 54, 56, and 58 °C, and trials were conducted in triplicate. Non-acid-adapted E. coli exhibited the highest thermal tolerance at pH 4.5 (D-value at 54 °C [D54 °C] of 20 ± 4 min and z-value of 6.2 °C), although on average, the D-values increased significantly (P < 0.01) due to acid adaptation. In acidified juices, the highest tolerance was observed in acid-adapted E. coli in samples adjusted to pH 3.7 with malic acid (D54 °C of 9 ± 2 min and z-value of 5.4 °C) and the lowest in unadapted E. coli at pH 3.3 acidified with acetic acid (D58 °C of 0.03 ± 0.01 min and z-value of 10.4 °C). For juices acidified to the same endpoint pH with different acids, E. coli was found to be more tolerant in samples acidified with malic acid, followed by lactic and acetic acids. Increasing the soluble solids content from 9.4 to 11.5 °Brix showed no

  1. Ecological and evolutionary influences on body size and shape in the Galápagos marine iguana (Amblyrhynchus cristatus).

    PubMed

    Chiari, Ylenia; Glaberman, Scott; Tarroso, Pedro; Caccone, Adalgisa; Claude, Julien

    2016-07-01

    Oceanic islands are often inhabited by endemic species that have undergone substantial morphological evolutionary change due to processes of multiple colonizations from various source populations, dispersal, and local adaptation. Galápagos marine iguanas are an example of an island endemic exhibiting high morphological diversity, including substantial body size variation among populations and sexes, but the causes and magnitude of this variation are not well understood. We obtained morphological measurements from marine iguanas throughout their distribution range. These data were combined with genetic and local environmental data from each population to investigate the effects of evolutionary history and environmental conditions on body size and shape variation and sexual dimorphism. Our results indicate that body size and shape are highly variable among populations. Sea surface temperature and island perimeter, but not evolutionary history as depicted by phylogeographic patterns in this species, explain variation in body size among populations. Conversely, evolutionary history, but not environmental parameters or island size, was found to influence variation in body shape among populations. Finally, in all populations except one, we found strong sexual dimorphism in body size and shape in which males are larger, with higher heads than females, while females have longer heads than males. Differences among populations suggest that plasticity and/or genetic adaptation may shape body size and shape variation in marine iguanas. This study will help target future investigations to address the contribution of plasticity versus genetic adaptation on size and shape variation in marine iguanas. PMID:27041683

  2. Hybrid Adaptive Flight Control with Model Inversion Adaptation

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan

    2011-01-01

    This study investigates a hybrid adaptive flight control method as a design possibility for a flight control system that can enable an effective adaptation strategy to deal with off-nominal flight conditions. The hybrid adaptive control blends both direct and indirect adaptive control in a model inversion flight control architecture. The blending of both direct and indirect adaptive control provides a much more flexible and effective adaptive flight control architecture than that with either direct or indirect adaptive control alone. The indirect adaptive control is used to update the model inversion controller by an on-line parameter estimation of uncertain plant dynamics based on two methods. The first parameter estimation method is an indirect adaptive law based on the Lyapunov theory, and the second method is a recursive least-squares indirect adaptive law. The model inversion controller is therefore made to adapt to changes in the plant dynamics due to uncertainty. As a result, the modeling error is reduced that directly leads to a decrease in the tracking error. In conjunction with the indirect adaptive control that updates the model inversion controller, a direct adaptive control is implemented as an augmented command to further reduce any residual tracking error that is not entirely eliminated by the indirect adaptive control.

  3. Effects of incomplete adaptation and disturbance in adaptive control.

    NASA Technical Reports Server (NTRS)

    Lindorff, D. P.

    1972-01-01

    In this paper consideration is given to the effects of disturbance and incomplete parameter adaptation on the performance of adaptive control systems in which Liapunov theory is used in deriving the control law. A design equation for the bounded error is derived. It is further shown that parameters in the adaptive controller may not converge in the presence of disturbance unless the input signal has a rich enough frequency constant. Design examples are presented.

  4. Mixed integer evolution strategies for parameter optimization.

    PubMed

    Li, Rui; Emmerich, Michael T M; Eggermont, Jeroen; Bäck, Thomas; Schütz, M; Dijkstra, J; Reiber, J H C

    2013-01-01

    Evolution strategies (ESs) are powerful probabilistic search and optimization algorithms gleaned from biological evolution theory. They have been successfully applied to a wide range of real world applications. The modern ESs are mainly designed for solving continuous parameter optimization problems. Their ability to adapt the parameters of the multivariate normal distribution used for mutation during the optimization run makes them well suited for this domain. In this article we describe and study mixed integer evolution strategies (MIES), which are natural extensions of ES for mixed integer optimization problems. MIES can deal with parameter vectors consisting not only of continuous variables but also with nominal discrete and integer variables. Following the design principles of the canonical evolution strategies, they use specialized mutation operators tailored for the aforementioned mixed parameter classes. For each type of variable, the choice of mutation operators is governed by a natural metric for this variable type, maximal entropy, and symmetry considerations. All distributions used for mutation can be controlled in their shape by means of scaling parameters, allowing self-adaptation to be implemented. After introducing and motivating the conceptual design of the MIES, we study the optimality of the self-adaptation of step sizes and mutation rates on a generalized (weighted) sphere model. Moreover, we prove global convergence of the MIES on a very general class of problems. The remainder of the article is devoted to performance studies on artificial landscapes (barrier functions and mixed integer NK landscapes), and a case study in the optimization of medical image analysis systems. In addition, we show that with proper constraint handling techniques, MIES can also be applied to classical mixed integer nonlinear programming problems. PMID:22122384

  5. Equilibrium Shaping

    NASA Astrophysics Data System (ADS)

    Izzo, Dario; Petazzi, Lorenzo

    2006-08-01

    We present a satellite path planning technique able to make identical spacecraft aquire a given configuration. The technique exploits a behaviour-based approach to achieve an autonomous and distributed control over the relative geometry making use of limited sensorial information. A desired velocity is defined for each satellite as a sum of different contributions coming from generic high level behaviours: forcing the final desired configuration the behaviours are further defined by an inverse dynamic calculation dubbed Equilibrium Shaping. We show how considering only three different kind of behaviours it is possible to acquire a number of interesting formations and we set down the theoretical framework to find the entire set. We find that allowing a limited amount of communication the technique may be used also to form complex lattice structures. Several control feedbacks able to track the desired velocities are introduced and discussed. Our results suggest that sliding mode control is particularly appropriate in connection with the developed technique.

  6. Multiscale characterization and analysis of shapes

    DOEpatents

    Prasad, Lakshman; Rao, Ramana

    2002-01-01

    An adaptive multiscale method approximates shapes with continuous or uniformly and densely sampled contours, with the purpose of sparsely and nonuniformly discretizing the boundaries of shapes at any prescribed resolution, while at the same time retaining the salient shape features at that resolution. In another aspect, a fundamental geometric filtering scheme using the Constrained Delaunay Triangulation (CDT) of polygonized shapes creates an efficient parsing of shapes into components that have semantic significance dependent only on the shapes' structure and not on their representations per se. A shape skeletonization process generalizes to sparsely discretized shapes, with the additional benefit of prunability to filter out irrelevant and morphologically insignificant features. The skeletal representation of characters of varying thickness and the elimination of insignificant and noisy spurs and branches from the skeleton greatly increases the robustness, reliability and recognition rates of character recognition algorithms.

  7. Adaptive human behavior in epidemiological models.

    PubMed

    Fenichel, Eli P; Castillo-Chavez, Carlos; Ceddia, M G; Chowell, Gerardo; Parra, Paula A Gonzalez; Hickling, Graham J; Holloway, Garth; Horan, Richard; Morin, Benjamin; Perrings, Charles; Springborn, Michael; Velazquez, Leticia; Villalobos, Cristina

    2011-04-12

    The science and management of infectious disease are entering a new stage. Increasingly public policy to manage epidemics focuses on motivating people, through social distancing policies, to alter their behavior to reduce contacts and reduce public disease risk. Person-to-person contacts drive human disease dynamics. People value such contacts and are willing to accept some disease risk to gain contact-related benefits. The cost-benefit trade-offs that shape contact behavior, and hence the course of epidemics, are often only implicitly incorporated in epidemiological models. This approach creates difficulty in parsing out the effects of adaptive behavior. We use an epidemiological-economic model of disease dynamics to explicitly model the trade-offs that drive person-to-person contact decisions. Results indicate that including adaptive human behavior significantly changes the predicted course of epidemics and that this inclusion has implications for parameter estimation and interpretation and for the development of social distancing policies. Acknowledging adaptive behavior requires a shift in thinking about epidemiological processes and parameters. PMID:21444809

  8. Adaptive human behavior in epidemiological models

    PubMed Central

    Fenichel, Eli P.; Castillo-Chavez, Carlos; Ceddia, M. G.; Chowell, Gerardo; Parra, Paula A. Gonzalez; Hickling, Graham J.; Holloway, Garth; Horan, Richard; Morin, Benjamin; Perrings, Charles; Springborn, Michael; Velazquez, Leticia; Villalobos, Cristina

    2011-01-01

    The science and management of infectious disease are entering a new stage. Increasingly public policy to manage epidemics focuses on motivating people, through social distancing policies, to alter their behavior to reduce contacts and reduce public disease risk. Person-to-person contacts drive human disease dynamics. People value such contacts and are willing to accept some disease risk to gain contact-related benefits. The cost–benefit trade-offs that shape contact behavior, and hence the course of epidemics, are often only implicitly incorporated in epidemiological models. This approach creates difficulty in parsing out the effects of adaptive behavior. We use an epidemiological–economic model of disease dynamics to explicitly model the trade-offs that drive person-to-person contact decisions. Results indicate that including adaptive human behavior significantly changes the predicted course of epidemics and that this inclusion has implications for parameter estimation and interpretation and for the development of social distancing policies. Acknowledging adaptive behavior requires a shift in thinking about epidemiological processes and parameters. PMID:21444809

  9. Adaptive Heat Engine

    NASA Astrophysics Data System (ADS)

    Allahverdyan, A. E.; Babajanyan, S. G.; Martirosyan, N. H.; Melkikh, A. V.

    2016-07-01

    A major limitation of many heat engines is that their functioning demands on-line control and/or an external fitting between the environmental parameters (e.g., temperatures of thermal baths) and internal parameters of the engine. We study a model for an adaptive heat engine, where—due to feedback from the functional part—the engine's structure adapts to given thermal baths. Hence, no on-line control and no external fitting are needed. The engine can employ unknown resources; it can also adapt to results of its own functioning that make the bath temperatures closer. We determine resources of adaptation and relate them to the prior information available about the environment.

  10. Telescope Adaptive Optics Code

    SciTech Connect

    Phillion, D.

    2005-07-28

    The Telescope AO Code has general adaptive optics capabilities plus specialized models for three telescopes with either adaptive optics or active optics systems. It has the capability to generate either single-layer or distributed Kolmogorov turbulence phase screens using the FFT. Missing low order spatial frequencies are added using the Karhunen-Loeve expansion. The phase structure curve is extremely dose to the theoreUcal. Secondly, it has the capability to simulate an adaptive optics control systems. The default parameters are those of the Keck II adaptive optics system. Thirdly, it has a general wave optics capability to model the science camera halo due to scintillation from atmospheric turbulence and the telescope optics. Although this capability was implemented for the Gemini telescopes, the only default parameter specific to the Gemini telescopes is the primary mirror diameter. Finally, it has a model for the LSST active optics alignment strategy. This last model is highly specific to the LSST

  11. Adaptive Heat Engine.

    PubMed

    Allahverdyan, A E; Babajanyan, S G; Martirosyan, N H; Melkikh, A V

    2016-07-15

    A major limitation of many heat engines is that their functioning demands on-line control and/or an external fitting between the environmental parameters (e.g., temperatures of thermal baths) and internal parameters of the engine. We study a model for an adaptive heat engine, where-due to feedback from the functional part-the engine's structure adapts to given thermal baths. Hence, no on-line control and no external fitting are needed. The engine can employ unknown resources; it can also adapt to results of its own functioning that make the bath temperatures closer. We determine resources of adaptation and relate them to the prior information available about the environment. PMID:27472104

  12. Effect of adaptation and pulp density on bioleaching of mine waste using indigenous acidophilic bacteria

    NASA Astrophysics Data System (ADS)

    Cho, K.; Kim, B.; Lee, D.; Choi, N.; Park, C.

    2011-12-01

    Adaptation to environment is a natural phenomena that takes place in many animals, plants and microorganisms. These adapted organisms achieve stronger applicability than unadapted organisms after habitation in a specific environment for a long time. In the biohydrometallurgical industry, adaptation to special environment conditions by selective culturing is the most popular method for improving bioleaching activity of strains-although that is time consuming. This study investigated the influence of the bioleaching efficiency of mine waste under batch experimental conditions (adaptation and pulp density) using the indigenous acidophilic bacteria collected from acid mine drainage in Go-seong and Yeon-hwa, Korea. We conducted the batch experiments at the influences of parameters, such as the adaptation of bacteria and pulp density of the mine waste. In the adaptation case, the value of pH in 1'st adaptation bacteria sample exhibited lower than in 2'nd adaptation bacteria sample. And the content of both Cu and Zn at 1'st adaptation bacteria sample appeared lower than at 2'nd adaptation bacteria sample. In the SEM analysis, the rod-shaped bacteria with 1μm in length were observed on the filter paper (pore size - 0.45μm). The results of pulp density experiments revealed that the content of both Cu and Zn increased with increasing pulp density, since the increment of pulp density resulted in the enhancement of bioleaching capacity.

  13. Adaptive Management

    EPA Science Inventory

    Adaptive management is an approach to natural resource management that emphasizes learning through management where knowledge is incomplete, and when, despite inherent uncertainty, managers and policymakers must act. Unlike a traditional trial and error approach, adaptive managem...

  14. Symmetry and scale orient Min protein patterns in shaped bacterial sculptures

    PubMed Central

    Wu, Fabai; van Schie, Bas G.C.; Keymer, Juan E.; Dekker, Cees

    2016-01-01

    The boundary of a cell defines the shape and scale for its subcellular organisation. However, the effects of the cell’s spatial boundaries as well as the geometry sensing and scale adaptation of intracellular molecular networks remain largely unexplored. Here, we show that living bacterial cells can be ‘sculpted’ into defined shapes, such as squares and rectangles, which are used to explore the spatial adaptation of Min proteins that oscillate pole-to-pole in rod-shape Escherichia coli to assist cell division. In a wide geometric parameter space, ranging from 2x1x1 to 11x6x1 μm3, Min proteins exhibit versatile oscillation patterns, sustaining rotational, longitudinal, diagonal, stripe, and even transversal modes. These patterns are found to directly capture the symmetry and scale of the cell boundary, and the Min concentration gradients scale in adaptation to the cell size within a characteristic length range of 3–6 μm. Numerical simulations reveal that local microscopic Turing kinetics of Min proteins can yield global symmetry selection, gradient scaling, and an adaptive range, when and only when facilitated by the three-dimensional confinement of cell boundary. These findings cannot be explained by previous geometry-sensing models based on the longest distance, membrane area or curvature, and reveal that spatial boundaries can facilitate simple molecular interactions to result in far more versatile functions than previously understood. PMID:26098227

  15. Cellinoid shape model for Hipparcos data

    NASA Astrophysics Data System (ADS)

    Lu, Xiao-Ping; Cellino, Alberto; Hestroffer, Daniel; Ip, Wing-Huen

    2016-03-01

    Being intermediate between a regular triaxial ellipsoid shape and a more complex convex shape, the so-called "cellinoid" shape model consists of eight octants of eight ellipsoids with the constraint that neighbouring octants share two common axes. The resulting variety of possible shapes, obtained at the cost of only three extra parameters to be added to models of regular ellipsoids, can be employed to efficiently simulate asteroids with irregular shapes. This article shows how the cellinoid shape model can be applied to the inversion of sparse photometric data, such as Hipparcos data. In order to make the model more efficient and convenient to use, an error analysis is discussed and numerically confirmed. Finally, we determine physical parameters of several asteroids, including their shape, rotational period and pole orientation, by applying our model to Hipparcos data.

  16. Shape-dependent canny edge detector

    NASA Astrophysics Data System (ADS)

    Panetta, Karen A.; Agaian, Sos S.; Nercessian, Shahan C.; Almunstashri, Ali A.

    2011-08-01

    Edges characterize the boundaries of objects in images and are informative structural cues for computer vision and target/object detection and recognition systems. The Canny edge detector is widely regarded as the edge detection standard. It is fairly adaptable to different environments, as its parametric nature attempts to tailor the detection of edges based on image-dependent characteristics or the particular requirements of a given implementation. Though it has been used in a myriad of image processing tasks, the Canny edge detector is still vulnerable to edge losses, localization errors, and noise sensitivity. These issues are largely due to the key tradeoff made in the scale and size of the edge detection filters used by the algorithm. Small-scaled filters are sensitive to edges but also to noise, whereas large-scaled filters are robust to noise but could filter out fine details. In this paper, novel edge detection kernel generalizations and a shape-dependent edge detector are introduced to alleviate these shortcomings. While most standard edge detection algorithms are based on convolving the input image with fixed size square kernels, this paper will illustrate the benefits of different filter sizes, and more importantly, different kernel shapes for edge detection. Moreover, new edge fusion methods are introduced to more effectively combine the individual edge responses. Existing edge detectors, including the Canny edge detector, can be obtained from the generalized edge detector by specifying corresponding parameters and kernel shapes. The proposed representations and edge detector have been qualitatively and quantitatively evaluated on several different types of image data. Computer simulations demonstrate that nonsquare kernel approaches can outperform square kernel approaches such as Canny, Sobel, Prewitt, Roberts, and others, providing better tradeoffs between noise rejection, accurate edge localization, and resolution. Where possible, Pratt's figure of

  17. Bayesian Vision for Shape Recovery

    NASA Technical Reports Server (NTRS)

    Jalobeanu, Andre

    2004-01-01

    We present a new Bayesian vision technique that aims at recovering a shape from two or more noisy observations taken under similar lighting conditions. The shape is parametrized by a piecewise linear height field, textured by a piecewise linear irradiance field, and we assume Gaussian Markovian priors for both shape vertices and irradiance variables. The observation process. also known as rendering, is modeled by a non-affine projection (e.g. perspective projection) followed by a convolution with a piecewise linear point spread function. and contamination by additive Gaussian noise. We assume that the observation parameters are calibrated beforehand. The major novelty of the proposed method consists of marginalizing out the irradiances considered as nuisance parameters, which is achieved by Laplace approximations. This reduces the inference to minimizing an energy that only depends on the shape vertices, and therefore allows an efficient Iterated Conditional Mode (ICM) optimization scheme to be implemented. A Gaussian approximation of the posterior shape density is computed, thus providing estimates both the geometry and its uncertainty. We illustrate the effectiveness of the new method by shape reconstruction results in a 2D case. A 3D version is currently under development and aims at recovering a surface from multiple images, reconstructing the topography by marginalizing out both albedo and shading.

  18. Compacted carbonaceous shapes and process for making the same

    SciTech Connect

    Du Broff, W.; Craig, G.H.; Veslocki, T.A.

    1983-11-01

    Compacted carbonaceous shapes are produced by mixing a particulate carbonaceous material with a binder, forming green shapes from the mixture, and heating the green shapes by induction heating or microwave heating or a combination thereof. The process is particularly adapted for making formcoke.

  19. The Limits to Adaptation: A Systems Approach

    EPA Science Inventory

    The ability to adapt to climate change is delineated by capacity thresholds, after which climate damages begin to overwhelm the adaptation response. Such thresholds depend upon physical properties (natural processes and engineering parameters), resource constraints (expressed th...

  20. Simple method for model reference adaptive control

    NASA Technical Reports Server (NTRS)

    Seraji, H.

    1989-01-01

    A simple method is presented for combined signal synthesis and parameter adaptation within the framework of model reference adaptive control theory. The results are obtained using a simple derivation based on an improved Liapunov function.

  1. Shaping propagation invariant laser beams

    NASA Astrophysics Data System (ADS)

    Soskind, Michael; Soskind, Rose; Soskind, Yakov

    2015-11-01

    Propagation-invariant structured laser beams possess several unique properties and play an important role in various photonics applications. The majority of propagation invariant beams are produced in the form of laser modes emanating from stable laser cavities. Therefore, their spatial structure is limited by the intracavity mode formation. We show that several types of anamorphic optical systems (AOSs) can be effectively employed to shape laser beams into a variety of propagation invariant structured fields with different shapes and phase distributions. We present a propagation matrix approach for designing AOSs and defining mode-matching conditions required for preserving propagation invariance of the output shaped fields. The propagation matrix approach was selected, as it provides a more straightforward approach in designing AOSs for shaping propagation-invariant laser beams than the alternative technique based on the Gouy phase evolution, especially in the case of multielement AOSs. Several practical configurations of optical systems that are suitable for shaping input laser beams into a diverse variety of structured propagation invariant laser beams are also presented. The laser beam shaping approach was applied by modeling propagation characteristics of several input laser beam types, including Hermite-Gaussian, Laguerre-Gaussian, and Ince-Gaussian structured field distributions. The influence of the Ince-Gaussian beam semifocal separation parameter and the azimuthal orientation between the input laser beams and the AOSs onto the resulting shape of the propagation invariant laser beams is presented as well.

  2. Adaptive SPECT

    PubMed Central

    Barrett, Harrison H.; Furenlid, Lars R.; Freed, Melanie; Hesterman, Jacob Y.; Kupinski, Matthew A.; Clarkson, Eric; Whitaker, Meredith K.

    2008-01-01

    Adaptive imaging systems alter their data-acquisition configuration or protocol in response to the image information received. An adaptive pinhole single-photon emission computed tomography (SPECT) system might acquire an initial scout image to obtain preliminary information about the radiotracer distribution and then adjust the configuration or sizes of the pinholes, the magnifications, or the projection angles in order to improve performance. This paper briefly describes two small-animal SPECT systems that allow this flexibility and then presents a framework for evaluating adaptive systems in general, and adaptive SPECT systems in particular. The evaluation is in terms of the performance of linear observers on detection or estimation tasks. Expressions are derived for the ideal linear (Hotelling) observer and the ideal linear (Wiener) estimator with adaptive imaging. Detailed expressions for the performance figures of merit are given, and possible adaptation rules are discussed. PMID:18541485

  3. Target parameter estimation

    NASA Technical Reports Server (NTRS)

    Hocking, W. K.

    1989-01-01

    The objective of any radar experiment is to determine as much as possible about the entities which scatter the radiation. This review discusses many of the various parameters which can be deduced in a radar experiment, and also critically examines the procedures used to deduce them. Methods for determining the mean wind velocity, the RMS fluctuating velocities, turbulence parameters, and the shapes of the scatterers are considered. Complications with these determinations are discussed. It is seen throughout that a detailed understanding of the shape and cause of the scatterers is important in order to make better determinations of these various quantities. Finally, some other parameters, which are less easily acquired, are considered. For example, it is noted that momentum fluxes due to buoyancy waves and turbulence can be determined, and on occasions radars can be used to determine stratospheric diffusion coefficients and even temperature profiles in the atmosphere.

  4. Shape control using sidewall imaging

    NASA Astrophysics Data System (ADS)

    Su, Bo; Oshana, Ramiel; Menaker, Mina; Barak, Yogev; Shi, Xuelong

    2000-06-01

    As gate widths shrink below 0.18 micrometer, the SPC (Statistical Process Control) based CD (Critical Dimension) control in lithography process becomes more difficult. Increasing requirements of a shrinking process window have called on the need for advanced CD control using a closed-loop feedback mechanism. This concept has been gaining momentum and shows promising advantages in shortening the time of feedback control. However, the current closed-loop feedback links only the average CD of a lot and the exposure dose (E), leaving out another critical lithography parameter -- stepper, or scanner, defocus (F). Up until now, F has been assumed constant while E has been shown to have one-to-one correlation with CD. Such an assumption is justified for feature sizes larger than 0.25 micrometer with a usable DOF (Depth Of Focus) of more than 1 micrometer. For 0.25 micrometer and below technologies, stepper defocus induces rapid feature profile, as well as CD, changes. Therefore, one parameter (exposure dose versus CD) feedback is not adequate enough to control CD in photolithography and a two-parameter (exposure dose and stepper defocus versus CD) feedback is needed. For stepper defocus variation, resist feature shape needs to be monitored in-line. We will present an innovative way of shape monitoring through sidewall imaging. The scanning beam is bent up to 5 degrees, so that a feature can be viewed from a tilted angle. Such tilted view greatly enhances edge resolution. Shape monitoring applications based on sidewall imaging will be presented. With both CD and shape are monitored in photolithography process, two critical parameters, i.e., exposure dose and defocus, can be easily controlled. Such shape control mechanism provides the base for two-parameter feedback loop.

  5. A variable parameter parametric snake method

    NASA Astrophysics Data System (ADS)

    Marouf, A.; Houacine, A.

    2015-12-01

    In this paper, we introduce a new approach to parametric snake method by using variable snake parameters. Adopting fixed parameter values for all points of the snake, as usual, constitutes by itself a limitation that leads to poor performances in terms of convergence and tracking properties. A more adapted choice should be the one that allows selection depending on the image region properties as on the contour shape and position. However, such variability is not an easy task in general and a precise method need to be defined to assure contour point dependent tuning at iterations. We were particularly interested in applying this idea to the recently presented parametric method [1]. In the work mentioned, an attraction term is used to improve the convergence of the standard parametric snake without a significant increase in computational load. We show here, that improved performances can ensue from applying variable parameter concepts. For this purpose, the method is first analyzed and then a procedure is developed to assure an automatic variable parameter tuning. The interest of our approach is illustrated through object segmentation results.

  6. Pathogen population bottlenecks and adaptive landscapes: overcoming the barriers to disease emergence.

    PubMed

    Geoghegan, Jemma L; Senior, Alistair M; Holmes, Edward C

    2016-08-31

    Emerging diseases are a major challenge to public health. Revealing the evolutionary processes that allow novel pathogens to adapt to new hosts, also the potential barriers to host adaptation, is central to understanding the drivers of disease emergence. In particular, it is unclear how the genetics and ecology of pathogens interact to shape the likelihood of successful cross-species transmission. To better understand the determinants of host adaptation and emergence, we modelled key aspects of pathogen evolutionary dynamics at both intra- and inter-host scales, using parameter values similar to those observed in influenza virus. We considered the possibility of acquiring the necessary host adaptive mutations both before ('off-the-shelf' emergence) and after ('tailor-made' emergence) a virus is transmitted from a donor to a new recipient species. Under both scenarios, population bottlenecks at inter-host transmission act as a major barrier to host adaptation, greatly limiting the number of adaptive mutations that are able to cross the species barrier. In addition, virus emergence is hindered if the fitness valley between the donor and recipient hosts is either too steep or too shallow. Overall, our results reveal where in evolutionary parameter space a virus could adapt to and become transmissible in a new species. PMID:27581875

  7. Shape-Shifting Plastic

    SciTech Connect

    2015-05-20

    A new plastic developed by ORNL and Washington State University transforms from its original shape through a series of temporary shapes and returns to its initial form. The shape-shifting process is controlled through changes in temperature

  8. Shape Determination for Deformed Electromagnetic Cavities

    SciTech Connect

    Akcelik, Volkan; Ko, Kwok; Lee, Lie-Quan; Li, Zhenghai; Ng, Cho-Kuen; Xiao, Liling; /SLAC

    2007-12-10

    The measured physical parameters of a superconducting cavity differ from those of the designed ideal cavity. This is due to shape deviations caused by both loose machine tolerances during fabrication and by the tuning process for the accelerating mode. We present a shape determination algorithm to solve for the unknown deviations from the ideal cavity using experimentally measured cavity data. The objective is to match the results of the deformed cavity model to experimental data through least-squares minimization. The inversion variables are unknown shape deformation parameters that describe perturbations of the ideal cavity. The constraint is the Maxwell eigenvalue problem. We solve the nonlinear optimization problem using a line-search based reduced space Gauss-Newton method where we compute shape sensitivities with a discrete adjoint approach. We present two shape determination examples, one from synthetic and the other from experimental data. The results demonstrate that the proposed algorithm is very effective in determining the deformed cavity shape.

  9. Adaptive Models for Gene Networks

    PubMed Central

    Shin, Yong-Jun; Sayed, Ali H.; Shen, Xiling

    2012-01-01

    Biological systems are often treated as time-invariant by computational models that use fixed parameter values. In this study, we demonstrate that the behavior of the p53-MDM2 gene network in individual cells can be tracked using adaptive filtering algorithms and the resulting time-variant models can approximate experimental measurements more accurately than time-invariant models. Adaptive models with time-variant parameters can help reduce modeling complexity and can more realistically represent biological systems. PMID:22359614

  10. Tooth - abnormal shape

    MedlinePlus

    Hutchinson incisors; Abnormal tooth shape; Peg teeth; Mulberry teeth; Conical teeth ... The appearance of normal teeth varies, especially the molars. ... conditions. Specific diseases can affect tooth shape, tooth ...

  11. Tooth - abnormal shape

    MedlinePlus

    Hutchinson incisors; Abnormal tooth shape; Peg teeth; Mulberry teeth; Conical teeth ... from many different conditions. Specific diseases can affect tooth shape, tooth color, time of appearance, or absence ...

  12. The Thoracic Shape of Hominoids

    PubMed Central

    Chan, Lap Ki

    2014-01-01

    In hominoids, the broad thorax has been assumed to contribute to their dorsal scapular position. However, the dorsoventral diameter of their cranial thorax was found in one study to be longer in hominoids. There are insufficient data on thoracic shape to explain the relationship between broad thorax and dorsal scapular position. The current study presents data on multilevel cross-sectional shape and volume distribution in a range of primates. Biplanar radiographs of intact fluid-preserved cadavers were taken to measure the cross-sectional shape of ten equally spaced levels through the sternum (called decisternal levels) and the relative volume of the nine intervening thoracic segments. It was found that the cranial thorax of hominoids is larger and broader (except in the first two decisternal levels) than that of other primates. The cranial thorax of hominoids has a longer dorsoventral diameter because the increase in dorsoventral diameter caused by the increase in the volume of the cranial thorax overcompensates for the decrease caused by the broadening of the cranial thorax. The larger and broader cranial thorax in hominoids can be explained as a locomotor adaptation for scapular gliding and as a respiratory adaptation for reducing the effects of orthograde posture on ventilation-perfusion inequality. PMID:24818026

  13. The thoracic shape of hominoids.

    PubMed

    Chan, Lap Ki

    2014-01-01

    In hominoids, the broad thorax has been assumed to contribute to their dorsal scapular position. However, the dorsoventral diameter of their cranial thorax was found in one study to be longer in hominoids. There are insufficient data on thoracic shape to explain the relationship between broad thorax and dorsal scapular position. The current study presents data on multilevel cross-sectional shape and volume distribution in a range of primates. Biplanar radiographs of intact fluid-preserved cadavers were taken to measure the cross-sectional shape of ten equally spaced levels through the sternum (called decisternal levels) and the relative volume of the nine intervening thoracic segments. It was found that the cranial thorax of hominoids is larger and broader (except in the first two decisternal levels) than that of other primates. The cranial thorax of hominoids has a longer dorsoventral diameter because the increase in dorsoventral diameter caused by the increase in the volume of the cranial thorax overcompensates for the decrease caused by the broadening of the cranial thorax. The larger and broader cranial thorax in hominoids can be explained as a locomotor adaptation for scapular gliding and as a respiratory adaptation for reducing the effects of orthograde posture on ventilation-perfusion inequality. PMID:24818026

  14. Trajectory shaping rendezvous guidance

    NASA Astrophysics Data System (ADS)

    Klumpp, A. R.

    The Space Station will bring a great increase in rendezvous traffic. Formerly, rendezvous has been expensive in terms of time and crew involvement. Multiple trajectory adjustments on separate orbits have been required to meet safety, lighting, and geometry requirements. This paper describes a new guidance technique in which the approach trajectory is shaped by a sequence of velocity increments in order to satisfy multiple constraints within a single orbit. The approach phase is planned before the mission, leaving a group of free parameters that are optimized by onboard guidance. Fuel penalties are typically a few percent, compared to unshaped Hohmann transfers, and total fuel costs can be less than those of more time-consuming ways of meeting the same requirements.

  15. Shape Determination for Large Static Structures

    NASA Technical Reports Server (NTRS)

    Rodriguez, G.; Scheid, Robert E., Jr.

    1986-01-01

    Parameter and shape estimates updated from new measurements. Involves statistical structural analysis, statistical electromagneticfield analysis, filtering, measurement modeling, and iterative prediction/correction procedures. Estimating algorithms result from generalizations of Kalman statistical-filter theory.

  16. Symmetry and scale orient Min protein patterns in shaped bacterial sculptures

    NASA Astrophysics Data System (ADS)

    Wu, Fabai; van Schie, Bas G. C.; Keymer, Juan E.; Dekker, Cees

    2015-08-01

    The boundary of a cell defines the shape and scale of its subcellular organization. However, the effects of the cell's spatial boundaries as well as the geometry sensing and scale adaptation of intracellular molecular networks remain largely unexplored. Here, we show that living bacterial cells can be ‘sculpted’ into defined shapes, such as squares and rectangles, which are used to explore the spatial adaptation of Min proteins that oscillate pole-to-pole in rod-shaped Escherichia coli to assist cell division. In a wide geometric parameter space, ranging from 2 × 1 × 1 to 11 × 6 × 1 μm3, Min proteins exhibit versatile oscillation patterns, sustaining rotational, longitudinal, diagonal, stripe and even transversal modes. These patterns are found to directly capture the symmetry and scale of the cell boundary, and the Min concentration gradients scale with the cell size within a characteristic length range of 3-6 μm. Numerical simulations reveal that local microscopic Turing kinetics of Min proteins can yield global symmetry selection, gradient scaling and an adaptive range, when and only when facilitated by the three-dimensional confinement of the cell boundary. These findings cannot be explained by previous geometry-sensing models based on the longest distance, membrane area or curvature, and reveal that spatial boundaries can facilitate simple molecular interactions to result in far more versatile functions than previously understood.

  17. Optical axis jitter rejection for double overlapped adaptive optics systems

    NASA Astrophysics Data System (ADS)

    Luo, Qi; Luo, Xi; Li, Xinyang

    2016-04-01

    Optical axis jitters, or vibrations, which arise from wind shaking and structural oscillations of optical platforms, etc., cause a deleterious impact on the performance of adaptive optics systems. When conventional integrators are utilized to reject such high frequency and narrow-band disturbance, the benefits are quite small despite their acceptable capabilities to reject atmospheric turbulence. In our case, two suits of complete adaptive optics systems called double overlapped adaptive optics systems (DOAOS) are used to counteract both optical jitters and atmospheric turbulence. A novel algorithm aiming to remove vibrations is proposed by resorting to combine the Smith predictor and notch filer. With the help of loop shaping method, the algorithm will lead to an effective and stable controller, which makes the characteristics of error transfer function close to notch filters. On the basis of the spectral analysis of observed data, the peak frequency and bandwidth of vibrations can be identified in advance. Afterwards, the number of notch filters and their parameters will be determined using coordination descending method. The relationship between controller parameters and filtering features is discussed, and the robustness of the controller against varying parameters of the control object is investigated. Preliminary experiments are carried out to validate the proposed algorithms. The overall control performance of DOAOS is simulated. Results show that time delays are a limit of the performance, but the algorithm can be successfully implemented on our systems, which indicate that it has a great potential to reject jitters.

  18. Corrigendum to "Line shape parameters measurement and computations for self-broadened carbon dioxide transitions in the 30012 ← 00001 and 30013 ← 00001 bands, line mixing, and speed dependence" [J. Mol. Spectrosc. 245 (2007) 34-51

    NASA Astrophysics Data System (ADS)

    Predoi-Cross, A.; Unni, A. V.; Liu, W.; Schofield, I.; Holladay, C.; McKellar, A. R. W.; Hurtmans, D.

    2016-04-01

    The authors have been notified that there may be errors in the spectroscopic analysis presented in this published article. While the authors are re-analysing the spectra in a different approach, we would like to ask the readers to ignore the discussion of line parameters other than line positions. We would like to assure the readers that we are preparing follow-up manuscripts where we will compare our new results with those published earlier. These manuscripts will be submitted for publication in the same journal.

  19. Shape memory polymers

    DOEpatents

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  20. Preliminary Measurement of Lunar Particle Shapes.

    NASA Technical Reports Server (NTRS)

    Rickman, Doug

    2013-01-01

    Particle shape is a basic parameter and essential for many engineering applications. Very little data is published on the shape of lunar particles. An unpublished review found that even where the same samples were studied the results were contradictory, probably because of extremely small sample sizes. Other workers have made fundamental errors in algorithms. There are many ways to measure particle shape. One common approach is to examine the particles as intersected by a plain, such as a thin section. If discrete particles can be segmented from the image, programs such as ImageJ can readily obtain shape measurements for each particle.

  1. Moving Kriging shape function modeling of vector TARMA models for modal identification of linear time-varying structural systems

    NASA Astrophysics Data System (ADS)

    Yang, Wu; Liu, Li; Zhou, Si-Da; Ma, Zhi-Sai

    2015-10-01

    This work proposes a Moving Kriging (MK) shape function modeling method for modal identification of linear time-varying (LTV) structural systems based on vector time-dependent autoregressive moving average (VTARMA) models. It aims to avoid the functional subspaces selection of the conventional functional series VTARMA (FS-VTARMA) models. Instead of the common basis functions, it constructs the time-varying coefficients on the time nodes with the MK shape functions in a compact support domain. The merit of the MK shape function is to determine its shape parameters upon vector random vibration signals adaptively. Model identification is effectively dealt with through an optimization scheme that decomposes the identification problem into two subproblems: estimating model parameters via two-stage least squares (2SLS) method and estimating shape function parameters via a discrete-continuous-variable hybrid optimization. In addition, the model order selection is achieved by the optimization scheme. This method has been validated by a Monte Carlo study of simulation case and further by an experimental test case, and the performance and potential advantages are illustrated.

  2. Impact of space-time mesh adaptation on solute transport modeling in porous media

    NASA Astrophysics Data System (ADS)

    Esfandiar, Bahman; Porta, Giovanni; Perotto, Simona; Guadagnini, Alberto

    2015-02-01

    We implement a space-time grid adaptation procedure to efficiently improve the accuracy of numerical simulations of solute transport in porous media in the context of model parameter estimation. We focus on the Advection Dispersion Equation (ADE) for the interpretation of nonreactive transport experiments in laboratory-scale heterogeneous porous media. When compared to a numerical approximation based on a fixed space-time discretization, our approach is grounded on a joint automatic selection of the spatial grid and the time step to capture the main (space-time) system dynamics. Spatial mesh adaptation is driven by an anisotropic recovery-based error estimator which enables us to properly select the size, shape, and orientation of the mesh elements. Adaptation of the time step is performed through an ad hoc local reconstruction of the temporal derivative of the solution via a recovery-based approach. The impact of the proposed adaptation strategy on the ability to provide reliable estimates of the key parameters of an ADE model is assessed on the basis of experimental solute breakthrough data measured following tracer injection in a nonuniform porous system. Model calibration is performed in a Maximum Likelihood (ML) framework upon relying on the representation of the ADE solution through a generalized Polynomial Chaos Expansion (gPCE). Our results show that the proposed anisotropic space-time grid adaptation leads to ML parameter estimates and to model results of markedly improved quality when compared to classical inversion approaches based on a uniform space-time discretization.

  3. On the consistency of 2-D video disdrometers in measuring microphysical parameters of solid precipitation

    NASA Astrophysics Data System (ADS)

    Bernauer, F.; Hürkamp, K.; Rühm, W.; Tschiersch, J.

    2015-08-01

    Detailed characterization and classification of precipitation is an important task in atmospheric research. Line scanning 2-D video disdrometer devices are well established for rain observations. The two orthogonal views taken of each hydrometeor passing the sensitive area of the instrument qualify these devices especially for detailed characterization of nonsymmetric solid hydrometeors. However, in case of solid precipitation, problems related to the matching algorithm have to be considered and the user must be aware of the limited spatial resolution when size and shape descriptors are analyzed. Clarifying the potential of 2-D video disdrometers in deriving size, velocity and shape parameters from single recorded pictures is the aim of this work. The need of implementing a matching algorithm suitable for mixed- and solid-phase precipitation is highlighted as an essential step in data evaluation. For this purpose simple reproducible experiments with solid steel spheres and irregularly shaped Styrofoam particles are conducted. Self-consistency of shape parameter measurements is tested in 38 cases of real snowfall. As a result, it was found that reliable size and shape characterization with a relative standard deviation of less than 5 % is only possible for particles larger than 1 mm. For particles between 0.5 and 1.0 mm the relative standard deviation can grow up to 22 % for the volume, 17 % for size parameters and 14 % for shape descriptors. Testing the adapted matching algorithm with a reproducible experiment with Styrofoam particles, a mismatch probability of less than 3 % was found. For shape parameter measurements in case of real solid-phase precipitation, the 2-DVD shows self-consistent behavior.

  4. Telescope Adaptive Optics Code

    2005-07-28

    The Telescope AO Code has general adaptive optics capabilities plus specialized models for three telescopes with either adaptive optics or active optics systems. It has the capability to generate either single-layer or distributed Kolmogorov turbulence phase screens using the FFT. Missing low order spatial frequencies are added using the Karhunen-Loeve expansion. The phase structure curve is extremely dose to the theoreUcal. Secondly, it has the capability to simulate an adaptive optics control systems. The defaultmore » parameters are those of the Keck II adaptive optics system. Thirdly, it has a general wave optics capability to model the science camera halo due to scintillation from atmospheric turbulence and the telescope optics. Although this capability was implemented for the Gemini telescopes, the only default parameter specific to the Gemini telescopes is the primary mirror diameter. Finally, it has a model for the LSST active optics alignment strategy. This last model is highly specific to the LSST« less

  5. Adaptive Development

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The goal of this research is to develop and demonstrate innovative adaptive seal technologies that can lead to dramatic improvements in engine performance, life, range, and emissions, and enhance operability for next generation gas turbine engines. This work is concentrated on the development of self-adaptive clearance control systems for gas turbine engines. Researchers have targeted the high-pressure turbine (HPT) blade tip seal location for following reasons: Current active clearance control (ACC) systems (e.g., thermal case-cooling schemes) cannot respond to blade tip clearance changes due to mechanical, thermal, and aerodynamic loads. As such they are prone to wear due to the required tight running clearances during operation. Blade tip seal wear (increased clearances) reduces engine efficiency, performance, and service life. Adaptive sealing technology research has inherent impact on all envisioned 21st century propulsion systems (e.g. distributed vectored, hybrid and electric drive propulsion concepts).

  6. A new modelling method for non-convex shapes of asteroids based on photometric observations

    NASA Astrophysics Data System (ADS)

    Bartczak, P.; Santana-Ros, T.; Marciniak, A.; Michałowski, T.; Prętka-Ziomek, H.

    2014-04-01

    We present the new SAGE algorithm (Shaping Asteroids with Genetic Evolution) able to derive 3-D nonconvex shapes of asteroids and solving for their spin parameters using only disk-integrated photometry. A triangular mesh of 62 vertices is used as a seed during the parameters minimization, and the Catmull-Clark method is applied to generate bodies with higher resolution. The subroutines search for the sidereal period of rotation in a given range, and the spin axis orientation on the whole celestial sphere. A step-iterative algorithm is used to make the shape evolve under the minimization constrains between the synthetic generated photometry and the real observations. In order to generate the simulated lightcurves we propose the virtual frames algorithm. The algorithm simulates the pictures visible on hypothetical CCD frames and, using only elementary vector operations or quadratic algebraic equations, it takes into account all phase angle effects. Publicly available lightcurve data has been used to obtain a new non-convex model for (9) Metis and (433) Eros. The resulting body shapes are compared with the ones obtained using other observational techniques, such as adaptive optics and stellar occultations (for Metis) or the NEAR Shoemaker observations of Eros during its rendezvous.

  7. Deformable segmentation via sparse shape representation.

    PubMed

    Zhang, Shaoting; Zhan, Yiqiang; Dewan, Maneesh; Huang, Junzhou; Metaxas, Dimitris N; Zhou, Xiang Sean

    2011-01-01

    Appearance and shape are two key elements exploited in medical image segmentation. However, in some medical image analysis tasks, appearance cues are weak/misleading due to disease/artifacts and often lead to erroneous segmentation. In this paper, a novel deformable model is proposed for robust segmentation in the presence of weak/misleading appearance cues. Owing to the less trustable appearance information, this method focuses on the effective shape modeling with two contributions. First, a shape composition method is designed to incorporate shape prior on-the-fly. Based on two sparsity observations, this method is robust to false appearance information and adaptive to statistically insignificant shape modes. Second, shape priors are modeled and used in a hierarchical fashion. More specifically, by using affinity propagation method, our deformable surface is divided into multiple partitions, on which local shape models are built independently. This scheme facilitates a more compact shape prior modeling and hence a more robust and efficient segmentation. Our deformable model is applied on two very diverse segmentation problems, liver segmentation in PET-CT images and rodent brain segmentation in MR images. Compared to state-of-art methods, our method achieves better performance in both studies. PMID:21995060

  8. Visual adaptation to thin and fat bodies transfers across identity.

    PubMed

    Hummel, Dennis; Rudolf, Anne K; Untch, Karl-Heinz; Grabhorn, Ralph; Mohr, Harald M

    2012-01-01

    Visual perception is highly variable and can be influenced by the surrounding world. Previous research has revealed that body perception can be biased due to adaptation to thin or fat body shapes. The aim of the present study was to show that adaptation to certain body shapes and the resulting perceptual biases transfer across different identities of adaptation and test stimuli. We designed two similar adaptation experiments in which healthy female participants adapted to pictures of either thin or fat bodies and subsequently compared more or less distorted pictures of their own body to their actual body shape. In the first experiment (n = 16) the same identity was used as adaptation and test stimuli (i.e. pictures of the participant's own body) while in the second experiment (n = 16) we used pictures of unfamiliar thin or fat bodies as adaptation stimuli. We found comparable adaptation effects in both experiments: After adaptation to a thin body, participants rated a thinner than actual body picture to be the most realistic and vice versa. We therefore assume that adaptation to certain body shapes transfers across different identities. These results raise the questions of whether some type of natural adaptation occurs in everyday life. Natural and predominant exposure to certain bodily features like body shape--especially the thin ideal in Western societies--could bias perception for these features. In this regard, further research might shed light on aspects of body dissatisfaction and the development of body image disturbances in terms of eating disorders. PMID:22905232

  9. Fragment oriented molecular shapes.

    PubMed

    Hain, Ethan; Camacho, Carlos J; Koes, David Ryan

    2016-05-01

    Molecular shape is an important concept in drug design and virtual screening. Shape similarity typically uses either alignment methods, which dynamically optimize molecular poses with respect to the query molecular shape, or feature vector methods, which are computationally less demanding but less accurate. The computational cost of alignment can be reduced by pre-aligning shapes, as is done with the Volumetric-Aligned Molecular Shapes (VAMS) method. Here, we introduce and evaluate fragment oriented molecular shapes (FOMS), where shapes are aligned based on molecular fragments. FOMS enables the use of shape constraints, a novel method for precisely specifying molecular shape queries that provides the ability to perform partial shape matching and supports search algorithms that function on an interactive time scale. When evaluated using the challenging Maximum Unbiased Validation dataset, shape constraints were able to extract significantly enriched subsets of compounds for the majority of targets, and FOMS matched or exceeded the performance of both VAMS and an optimizing alignment method of shape similarity search. PMID:27085751

  10. The Hue of Shapes

    ERIC Educational Resources Information Center

    Albertazzi, Liliana; Da Pos, Osvaldo; Canal, Luisa; Micciolo, Rocco; Malfatti, Michela; Vescovi, Massimo

    2013-01-01

    This article presents an experimental study on the naturally biased association between shape and color. For each basic geometric shape studied, participants were asked to indicate the color perceived as most closely related to it, choosing from the Natural Color System Hue Circle. Results show that the choices of color for each shape were not…

  11. The Shape of Thought

    ERIC Educational Resources Information Center

    Markson, Lori; Diesendruck, Gil; Bloom, Paul

    2008-01-01

    When children learn the name of a novel object, they tend to extend that name to other objects similar in shape--a phenomenon referred to as the shape bias. Does the shape bias stem from learned associations between names and categories of objects, or does it derive from more general properties of children's understanding of language and the…

  12. Adaptive Thresholds

    SciTech Connect

    Bremer, P. -T.

    2014-08-26

    ADAPT is a topological analysis code that allow to compute local threshold, in particular relevance based thresholds for features defined in scalar fields. The initial target application is vortex detection but the software is more generally applicable to all threshold based feature definitions.

  13. Adaptive homeostasis.

    PubMed

    Davies, Kelvin J A

    2016-06-01

    Homeostasis is a central pillar of modern Physiology. The term homeostasis was invented by Walter Bradford Cannon in an attempt to extend and codify the principle of 'milieu intérieur,' or a constant interior bodily environment, that had previously been postulated by Claude Bernard. Clearly, 'milieu intérieur' and homeostasis have served us well for over a century. Nevertheless, research on signal transduction systems that regulate gene expression, or that cause biochemical alterations to existing enzymes, in response to external and internal stimuli, makes it clear that biological systems are continuously making short-term adaptations both to set-points, and to the range of 'normal' capacity. These transient adaptations typically occur in response to relatively mild changes in conditions, to programs of exercise training, or to sub-toxic, non-damaging levels of chemical agents; thus, the terms hormesis, heterostasis, and allostasis are not accurate descriptors. Therefore, an operational adjustment to our understanding of homeostasis suggests that the modified term, Adaptive Homeostasis, may be useful especially in studies of stress, toxicology, disease, and aging. Adaptive Homeostasis may be defined as follows: 'The transient expansion or contraction of the homeostatic range in response to exposure to sub-toxic, non-damaging, signaling molecules or events, or the removal or cessation of such molecules or events.' PMID:27112802

  14. Recent Advances in Shape Memory Soft Materials for Biomedical Applications.

    PubMed

    Chan, Benjamin Qi Yu; Low, Zhi Wei Kenny; Heng, Sylvester Jun Wen; Chan, Siew Yin; Owh, Cally; Loh, Xian Jun

    2016-04-27

    Shape memory polymers (SMPs) are smart and adaptive materials able to recover their shape through an external stimulus. This functionality, combined with the good biocompatibility of polymers, has garnered much interest for biomedical applications. In this review, we discuss the design considerations critical to the successful integration of SMPs for use in vivo. We also highlight recent work on three classes of SMPs: shape memory polymers and blends, shape memory polymer composites, and shape memory hydrogels. These developments open the possibility of incorporating SMPs into device design, which can lead to vast technological improvements in the biomedical field. PMID:27018814

  15. Temporal shape analysis via the spectral signature.

    PubMed

    Bernardis, Elena; Konukoglu, Ender; Ou, Yangming; Metaxas, Dimitris N; Desjardins, Benoit; Pohl, Kilian M

    2012-01-01

    In this paper, we adapt spectral signatures for capturing morphological changes over time. Advanced techniques for capturing temporal shape changes frequently rely on first registering the sequence of shapes and then analyzing the corresponding set of high dimensional deformation maps. Instead, we propose a simple encoding motivated by the observation that small shape deformations lead to minor refinements in the spectral signature composed of the eigenvalues of the Laplace operator. The proposed encoding does not require registration, since spectral signatures are invariant to pose changes. We apply our representation to the shapes of the ventricles extracted from 22 cine MR scans of healthy controls and Tetralogy of Fallot patients. We then measure the accuracy score of our encoding by training a linear classifier, which outperforms the same classifier based on volumetric measurements. PMID:23286031

  16. Reversible shape memory

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; Zhou, Jing; White, Sarah; Ashby, Valerie

    2012-02-01

    An ``Achilles' heel'' of shape memory materials is that shape transformations triggered by an external stimulus are usually irreversible. Here we present a new concept of reversible transitions between two well-defined shapes by controlling hierarchic crystallization of a dual-network elastomer. The reversibility was demonstrated for different types of shape transformations including rod bending, winding of a helical coil, and widening an aperture. The distinct feature of the reversible shape alterations is that both counter-shapes are infinitely stable at a temperature of exploitation. Shape reversibility is highly desirable property in many practical applications such as non-surgical removal of a previously inserted catheter and handfree wrapping up of an earlier unraveled solar sail on a space shuttle.

  17. General shape optimization capability

    NASA Technical Reports Server (NTRS)

    Chargin, Mladen K.; Raasch, Ingo; Bruns, Rudolf; Deuermeyer, Dawson

    1991-01-01

    A method is described for calculating shape sensitivities, within MSC/NASTRAN, in a simple manner without resort to external programs. The method uses natural design variables to define the shape changes in a given structure. Once the shape sensitivities are obtained, the shape optimization process is carried out in a manner similar to property optimization processes. The capability of this method is illustrated by two examples: the shape optimization of a cantilever beam with holes, loaded by a point load at the free end (with the shape of the holes and the thickness of the beam selected as the design variables), and the shape optimization of a connecting rod subjected to several different loading and boundary conditions.

  18. Adaptive control of robotic manipulators

    NASA Technical Reports Server (NTRS)

    Seraji, H.

    1987-01-01

    The author presents a novel approach to adaptive control of manipulators to achieve trajectory tracking by the joint angles. The central concept in this approach is the utilization of the manipulator inverse as a feedforward controller. The desired trajectory is applied as an input to the feedforward controller which behaves as the inverse of the manipulator at any operating point; the controller output is used as the driving torque for the manipulator. The controller gains are then updated by an adaptation algorithm derived from MRAC (model reference adaptive control) theory to cope with variations in the manipulator inverse due to changes of the operating point. An adaptive feedback controller and an auxiliary signal are also used to enhance closed-loop stability and to achieve faster adaptation. The proposed control scheme is computationally fast and does not require a priori knowledge of the complex dynamic model or the parameter values of the manipulator or the payload.

  19. Adaptive approaches to biosecurity governance.

    PubMed

    Cook, David C; Liu, Shuang; Murphy, Brendan; Lonsdale, W Mark

    2010-09-01

    This article discusses institutional changes that may facilitate an adaptive approach to biosecurity risk management where governance is viewed as a multidisciplinary, interactive experiment acknowledging uncertainty. Using the principles of adaptive governance, evolved from institutional theory, we explore how the concepts of lateral information flows, incentive alignment, and policy experimentation might shape Australia's invasive species defense mechanisms. We suggest design principles for biosecurity policies emphasizing overlapping complementary response capabilities and the sharing of invasive species risks via a polycentric system of governance. PMID:20561262

  20. LBT adaptive secondary preliminary design

    NASA Astrophysics Data System (ADS)

    Gallieni, Daniele; Del Vecchio, Ciro; Anaclerio, E.; Lazzarini, P. G.

    2000-07-01

    We report on the design of the two Gregorian adaptive secondary mirrors of the Large Binocular Telescope. Each adaptive secondary is a Zerodur shell having an external diameter of 911 mm and a thickness of about 1.5 mm. The deformable mirror is controlled by a pattern of 918 electromagnetic actuators. Its shape is referred to a stable ULE back plate by means of capacitive sensors co-located to the actuators pattern. The preliminary design of the system is addressed with particular attention to the reference plate optimization.

  1. Connector adapter

    NASA Technical Reports Server (NTRS)

    Hacker, Scott C. (Inventor); Dean, Richard J. (Inventor); Burge, Scott W. (Inventor); Dartez, Toby W. (Inventor)

    2007-01-01

    An adapter for installing a connector to a terminal post, wherein the connector is attached to a cable, is presented. In an embodiment, the adapter is comprised of an elongated collet member having a longitudinal axis comprised of a first collet member end, a second collet member end, an outer collet member surface, and an inner collet member surface. The inner collet member surface at the first collet member end is used to engage the connector. The outer collet member surface at the first collet member end is tapered for a predetermined first length at a predetermined taper angle. The collet includes a longitudinal slot that extends along the longitudinal axis initiating at the first collet member end for a predetermined second length. The first collet member end is formed of a predetermined number of sections segregated by a predetermined number of channels and the longitudinal slot.

  2. Analysis of the shape fluctuations of reconstituted membranes using GUVs made from lipid extracts of invertebrates

    PubMed Central

    Bouvrais, Hélène; Holmstrup, Martin; Westh, Peter; Ipsen, John H.

    2013-01-01

    Summary Changes in the physical properties of the lipid matrix of cell membranes have repeatedly been proposed to underlie stresses associated with e.g. drought, cold and xenobiotics. Therefore, the ability to experimentally monitor such properties is central to the fundamental physiological understanding of adaptive changes. Here, we test the analysis of shape fluctuations in membranes composed of lipid extracts from two soil invertebrates, and show that theories and experimental approaches previously developed for simpler liposomes may be applied directly to reconstituted membrane lipids. Specifically, we show how the bending rigidity of giant unilamellar liposomes of lipid extracts can be determined precisely. We suggest that future measurements of this parameter could elucidate mechanisms of adaptive processes such as changes in lipid composition and accumulation of protective osmolytes. PMID:23616921

  3. Nonlinear spatial focusing in random layered media by spectral pulse shaping

    NASA Astrophysics Data System (ADS)

    Han, Alex C.; Milner, Valery

    2016-02-01

    We demonstrate numerically a method of focusing two-photon fields inside one-dimensional random media. The approach is based on coherent control of backscattering achieved by adaptive spectral pulse shaping. The spectral phases of a femtosecond laser pulse are adjusted for the constructive interference of its backward-traveling components, resulting in an enhanced reflection from within the random system. A delayed forward-propagating second pulse overlaps with the controlled reflection, increasing the interpulse multiphoton field at a location determined by the delay between the two pulses. The technique is shown to be robust against the variations of the disorder and to work with realistic pulse-shaping parameters, hence enabling applications in controlling random lasing and multiphoton imaging in scattering materials.

  4. Modelling and experimental determination of the replication of a cylindrical shape relief

    NASA Astrophysics Data System (ADS)

    Sahli, M.; Millot, C.; Roques-Carmes, C.; Malek, C. Khan; Gelin, J. C.

    2007-04-01

    In that paper, one uses the concepts of contact mechanics to describe the quality of reproduction of cylindrical cavity shape by hot embossing. It results in a negative replica of the initial shape. This model takes into account the deformation of the polymer material imposed by the forming process. These results point out the influence of experimental parameters (temperature, pressure) as well as those of the elastic modulus (Young's modulus and Poisson's ratio). The analytical data are compared with the metrology results obtained using a scanning mechanical microscope in two or three-dimensional mode. The set of data enables a predictive approach of the engraving quality depending on the polymer mechanical properties. The final goal is to adapt this model to the hot embossing process.

  5. Effects of laser beam propagation and saturation on the spatial shape of sodium laser guide stars.

    PubMed

    Marc, Fabien; Guillet de Chatellus, Hugues; Pique, Jean-Paul

    2009-03-30

    The possibility to produce diffraction-limited images by large telescopes through Adaptive Optics is closely linked to the precision of measurement of the position of the guide star on the wavefront sensor. In the case of laser guide stars, many parameters can lead to a strong distortion on the shape of the LGS spot. Here we study the influence of both the saturation of the sodium layer excited by different types of lasers, the spatial quality of the laser mode at the ground and the influence of the atmospheric turbulence on the upward propagation of the laser beam. Both shape and intensity of the LGS spot are found to depend strongly on these three effects with important consequences on the precision on the wavefront analysis. PMID:19333251

  6. Adaptive sampler

    DOEpatents

    Watson, Bobby L.; Aeby, Ian

    1982-01-01

    An adaptive data compression device for compressing data having variable frequency content, including a plurality of digital filters for analyzing the content of the data over a plurality of frequency regions, a memory, and a control logic circuit for generating a variable rate memory clock corresponding to the analyzed frequency content of the data in the frequency region and for clocking the data into the memory in response to the variable rate memory clock.

  7. Adaptive sampler

    DOEpatents

    Watson, B.L.; Aeby, I.

    1980-08-26

    An adaptive data compression device for compressing data is described. The device has a frequency content, including a plurality of digital filters for analyzing the content of the data over a plurality of frequency regions, a memory, and a control logic circuit for generating a variable rate memory clock corresponding to the analyzed frequency content of the data in the frequency region and for clocking the data into the memory in response to the variable rate memory clock.

  8. Adaptive control of molecular alignment

    SciTech Connect

    Horn, C.; Wollenhaupt, M.; Krug, M.; Baumert, T.; Nalda, R. de; Banares, L.

    2006-03-15

    We demonstrate control on nonadiabatic molecular alignment by using a spectrally phase-shaped laser pulse. An evolutionary algorithm in a closed feedback loop has been used in order to find pulse shapes that maximize a given effect. In particular, this scheme has been applied to the optimization of total alignment, and to the control of the temporal structure of the alignment transient within a revival. Asymmetric temporal pulse shapes have been found to be very effective for the latter and have been studied separately in a single-parameter control scheme. Our experimental results are supported by numerical simulations.

  9. Adaptive antennas

    NASA Astrophysics Data System (ADS)

    Barton, P.

    1987-04-01

    The basic principles of adaptive antennas are outlined in terms of the Wiener-Hopf expression for maximizing signal to noise ratio in an arbitrary noise environment; the analogy with generalized matched filter theory provides a useful aid to understanding. For many applications, there is insufficient information to achieve the above solution and thus non-optimum constrained null steering algorithms are also described, together with a summary of methods for preventing wanted signals being nulled by the adaptive system. The three generic approaches to adaptive weight control are discussed; correlation steepest descent, weight perturbation and direct solutions based on sample matrix conversion. The tradeoffs between hardware complexity and performance in terms of null depth and convergence rate are outlined. The sidelobe cancellor technique is described. Performance variation with jammer power and angular distribution is summarized and the key performance limitations identified. The configuration and performance characteristics of both multiple beam and phase scan array antennas are covered, with a brief discussion of performance factors.

  10. Adaptive Dynamic Bayesian Networks

    SciTech Connect

    Ng, B M

    2007-10-26

    A discrete-time Markov process can be compactly modeled as a dynamic Bayesian network (DBN)--a graphical model with nodes representing random variables and directed edges indicating causality between variables. Each node has a probability distribution, conditional on the variables represented by the parent nodes. A DBN's graphical structure encodes fixed conditional dependencies between variables. But in real-world systems, conditional dependencies between variables may be unknown a priori or may vary over time. Model errors can result if the DBN fails to capture all possible interactions between variables. Thus, we explore the representational framework of adaptive DBNs, whose structure and parameters can change from one time step to the next: a distribution's parameters and its set of conditional variables are dynamic. This work builds on recent work in nonparametric Bayesian modeling, such as hierarchical Dirichlet processes, infinite-state hidden Markov networks and structured priors for Bayes net learning. In this paper, we will explain the motivation for our interest in adaptive DBNs, show how popular nonparametric methods are combined to formulate the foundations for adaptive DBNs, and present preliminary results.

  11. Non-convex shape models of asteroids based on photometric observations

    NASA Astrophysics Data System (ADS)

    Bartczak, P.; Santana-Ros, T.; Michalowski, T.

    2014-07-01

    We present the SAGE algorithm (Shaping Asteroids with Genetic Evolution) able to derive 3D non-convex shapes of asteroids and solving for their spin parameters using only disk-integrated photometry. A triangular mesh of 62 vertices is used as a seed during the parameters minimization, and the Catmull-Clark method (Catmull-Clark 1978) is applied to generate bodies with higher resolution. The subroutines search for the sidereal period of rotation in a given range, and the spin-axis orientation on the whole celestial sphere. A step-iterative algorithm is used to make the shape evolve under the minimization constraints between the synthetic generated photometry and the real observations. In order to generate the simulated lightcurves, we propose the virtual frames algorithm. The algorithm simulates the pictures visible on hypothetical CCD frames and, using only elementary vector operations or quadratic algebraic equations, it takes into account all phase-angle effects. Publicly available lightcurve data has been used to obtain a new non-convex model for (9) Metis, (21) Lutetia, and (433) Eros. The resulting body shapes are compared with the ones obtained using other observational techniques, such as adaptive optics and stellar occultations (Timerson et al. 2009) or the NEAR Shoemaker observations of Eros during its rendezvous (Zuber et al. 2000). We also assess the problem of the solution uniqueness for non-convex models, generating a family of shape solutions and studying the stability of the model features. Moreover, following the investigations presented in Kaasalainen & Torppa (2001) we study the discrepancy on the lightcurves between a non-convex shape model and its convex hull as a function of the phase angle. Finally, we compare the lightcurve fits obtained with other existing models for both ''classic'' and sparse-in-time photometry.

  12. Coupled adaptive complex networks

    NASA Astrophysics Data System (ADS)

    Shai, S.; Dobson, S.

    2013-04-01

    Adaptive networks, which combine topological evolution of the network with dynamics on the network, are ubiquitous across disciplines. Examples include technical distribution networks such as road networks and the internet, natural and biological networks, and social science networks. These networks often interact with or depend upon other networks, resulting in coupled adaptive networks. In this paper we study susceptible-infected-susceptible (SIS) epidemic dynamics on coupled adaptive networks, where susceptible nodes are able to avoid contact with infected nodes by rewiring their intranetwork connections. However, infected nodes can pass the disease through internetwork connections, which do not change with time: The dependencies between the coupled networks remain constant. We develop an analytical formalism for these systems and validate it using extensive numerical simulation. We find that stability is increased by increasing the number of internetwork links, in the sense that the range of parameters over which both endemic and healthy states coexist (both states are reachable depending on the initial conditions) becomes smaller. Finally, we find a new stable state that does not appear in the case of a single adaptive network but only in the case of weakly coupled networks, in which the infection is endemic in one network but neither becomes endemic nor dies out in the other. Instead, it persists only at the nodes that are coupled to nodes in the other network through internetwork links. We speculate on the implications of these findings.

  13. Ecomorphological variation in shell shape of the freshwater turtle Pseudemys concinna inhabiting different aquatic flow regimes.

    PubMed

    Rivera, Gabriel

    2008-12-01

    Populations of species that inhabit a range of environments frequently display divergent morphologies that correlate with differences in ecological parameters. The velocity of water flow (i.e., flow velocity) is a critical feature of aquatic environments that has been shown to influence morphology in a broad range of taxa. The focus of this study was to evaluate the relationship between flow velocity and shell morphology for males and females of the semi-aquatic freshwater turtle Pseudemys concinna. For both sexes, the carapace and plastron show significant morphological differences between habitats characterized by slow-flowing (i.e., lentic) and fast-flowing (i.e., lotic) water. In general, the most prominent pattern for both sexes is that the shells of individuals from lotic habitats are more streamlined (small height-to-length ratio) than the shells of individuals from lentic habitats. Of the two shell components (carapace and plastron), the carapace shows greater divergence between habitats, particularly for males. These results are consistent with adaptations to flow velocity, and suggest that variation in shape may be more constrained in females. I also provide empirical evidence for an adaptive benefit of the observed shape change (i.e., drag reduction) and a brief comment on the relative roles of genetic divergence and phenotypic plasticity in generating shape differences observed in this species. PMID:21669831

  14. Reconstruction Of Anatomical Shapes From Moire Contourographs

    NASA Astrophysics Data System (ADS)

    Saunders, Carl G.

    1983-07-01

    A Moire system which rotates an object in front of a slit camera has been used to obtain continuous photographic maps around amputee socket and shoe last shapes. Previous analysis methods required the use of IBM 370 hardware and extensive software overhead. Using a systematic manual digitizing technique and user-interactive FORTRAN software, the shape reconstruction has been easily performed on a PDP-11 minicomputer system. Both the digitizing technique and the software are oriented towards the shape reproduction process. Numerically controlled machining parameters are used to identify a "skewed" grid of required points along the cutter path. Linear interpolation and anti-interference techniques resulted in reproduction of shoe lasts to within 0.05 inches (1.2 millimeters) from the sensing axis. Difficulties were experienced in obtaining information to resolve the ends of the shapes. Current efforts focus on circumferential shape sensing of live subjects and automatic digitization of sensed data.

  15. Dip-molded t-shaped cannula

    NASA Technical Reports Server (NTRS)

    Broyles, H. F.; Cuddihy, E. F.; Moacanin, J.

    1978-01-01

    Cannula, fabricated out of polyetherurethane, has been designed for long-term service. Improved cannula is T-shaped to collect blood from both directions, thus replacing two conventional cannulas that are usually required and eliminating need for large surgical wound. It is fabricated by using dip-molding process that can be adapted to other elastomeric objects having complex shapes. Dimensions of cannula were chosen to optimize its blood-flow properties and to reduce danger of excessive clotting, making it suitable for continuous service up to 21 days in vein or artery of patient.

  16. Pressure enhanced penetration with shaped charge perforators

    DOEpatents

    Glenn, Lewis A.

    2001-01-01

    A downhole tool, adapted to retain a shaped charge surrounded by a superatmospherically pressurized light gas, is employed in a method for perforating a casing and penetrating reservoir rock around a wellbore. Penetration of a shaped charge jet can be enhanced by at least 40% by imploding a liner in the high pressure, light gas atmosphere. The gas pressure helps confine the jet on the axis of penetration in the latter stages of formation. The light gas, such as helium or hydrogen, is employed to keep the gas density low enough so as not to inhibit liner collapse.

  17. Pessimal shapes for packing

    NASA Astrophysics Data System (ADS)

    Kallus, Yoav

    2014-03-01

    The question of which convex shapes leave the most empty space in their densest packing is the subject of Reinhardt's conjecture in two dimensions and Ulam's conjecture in three dimensions. Such conjectures about pessimal packing shapes have proven notoriously difficult to make progress on. I show that the regular heptagon is a local pessimum among all convex shapes, and that the 3D ball is a local pessimum among origin-symmetric shapes. Any shape sufficiently close in the space of shapes to these local pessima can be packed at a greater efficiency than they. In two dimensions and in dimensions above three, the ball is not a local pessimum, so the situation in 3D is unusual and intriguing. I will discuss what conditions conspire to make the 3D ball a local pessimum and whether we can prove that it is also a global pessimum.

  18. Learning Deformable Shape Manifolds

    PubMed Central

    Rivera, Samuel; Martinez, Aleix

    2011-01-01

    We propose an approach to shape detection of highly deformable shapes in images via manifold learning with regression. Our method does not require shape key points be defined at high contrast image regions, nor do we need an initial estimate of the shape. We only require sufficient representative training data and a rough initial estimate of the object position and scale. We demonstrate the method for face shape learning, and provide a comparison to nonlinear Active Appearance Model. Our method is extremely accurate, to nearly pixel precision and is capable of accurately detecting the shape of faces undergoing extreme expression changes. The technique is robust to occlusions such as glasses and gives reasonable results for extremely degraded image resolutions. PMID:22308002

  19. A new class of energy based control laws for revolute robot arms - Tracking control, robustness enhancement and adaptive control

    NASA Technical Reports Server (NTRS)

    Wen, John T.; Kreutz, Kenneth; Bayard, David S.

    1988-01-01

    A class of joint-level control laws for all-revolute robot arms is introduced. The analysis is similar to the recently proposed energy Liapunov function approach except that the closed-loop potential function is shaped in accordance with the underlying joint space topology. By using energy Liapunov functions with the modified potential energy, a much simpler analysis can be used to show closed-loop global asymptotic stability and local exponential stability. When Coulomb and viscous friction and model parameter errors are present, a sliding-mode-like modification of the control law is proposed to add a robustness-enhancing outer loop. Adaptive control is also addressed within the same framework. A linear-in-the-parameters formulation is adopted, and globally asymptotically stable adaptive control laws are derived by replacing the model parameters in the nonadaptive control laws by their estimates.

  20. Development of multifunctional shape memory polymer foams

    NASA Astrophysics Data System (ADS)

    Song, Janice J.; Srivastava, Ijya; Naguib, Hani E.

    2015-05-01

    Shape memory polymers (SMP) are a class of stimuli-responsive materials which are able to respond to external stimulus such as temperature and deformation by changing their shape, and return to their original shape upon reversal or removal of the external stimulus. Although SMP materials have been studied extensively and have been used in a wide range of applications such as medicine, aerospace, and robotics, only few studies have looked at the potential of designing multifunctional SMP foams and blends. In this study, we investigate the feasibility of a design of SMP foam materials and blends. The actuator construct will contain a core SMP epoxy and blend of polylactic acid and polyurethane. The effects of the processing parameters of shape memory polymer (SMP) foams on the shape memory effect (SME) were investigated. The solid state foaming technique was employed to obtain the desired foamed cellular structure. One particular point of interest is to understand how the processing parameters affect the SMP and its glass transition temperature (Tg). By correctly tailoring these parameters it is possible to modify the SMP to have an improved shape memory effect SME.

  1. Dynamic Adaption of Vascular Morphology

    PubMed Central

    Okkels, Fridolin; Jacobsen, Jens Christian Brings

    2012-01-01

    The structure of vascular networks adapts continuously to meet changes in demand of the surrounding tissue. Most of the known vascular adaptation mechanisms are based on local reactions to local stimuli such as pressure and flow, which in turn reflects influence from the surrounding tissue. Here we present a simple two-dimensional model in which, as an alternative approach, the tissue is modeled as a porous medium with intervening sharply defined flow channels. Based on simple, physiologically realistic assumptions, flow-channel structure adapts so as to reach a configuration in which all parts of the tissue are supplied. A set of model parameters uniquely determine the model dynamics, and we have identified the region of the best-performing model parameters (a global optimum). This region is surrounded in parameter space by less optimal model parameter values, and this separation is characterized by steep gradients in the related fitness landscape. Hence it appears that the optimal set of parameters tends to localize close to critical transition zones. Consequently, while the optimal solution is stable for modest parameter perturbations, larger perturbations may cause a profound and permanent shift in systems characteristics. We suggest that the system is driven toward a critical state as a consequence of the ongoing parameter optimization, mimicking an evolutionary pressure on the system. PMID:23060814

  2. The Shape of Eros

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Looking at a few pictures of Eros under the right lighting conditions gives a reasonable idea of the shape of the asteroid, but analysis of NEAR Shoemaker data requires a very accurate digital model of Eros' shape. This 'shape model' helps the NEAR team analyze images and other types of data. For example, comparing the brightness of imaged regions with the orientation of the corresponding parts of the surface, taken from the shape model, allows scientists to determine whether bright areas are due to just surface orientation or also to surface properties. By 'filling

  3. Shape optimization for DSA

    NASA Astrophysics Data System (ADS)

    Ouaknin, Gaddiel; Laachi, Nabil; Delaney, Kris; Fredrickson, Glenn; Gibou, Frederic

    2016-03-01

    Directed self-assembly using block copolymers for positioning vertical interconnect access in integrated circuits relies on the proper shape of a confined domain in which polymers will self-assemble into the targeted design. Finding that shape, i.e., solving the inverse problem, is currently mainly based on trial and error approaches. We introduce a level-set based algorithm that makes use of a shape optimization strategy coupled with self-consistent field theory to solve the inverse problem in an automated way. It is shown that optimal shapes are found for different targeted topologies with accurate placement and distances between the different components.

  4. Colonization history shaped the immunity of the western house mouse.

    PubMed

    Tian, Jundong; Hofer, Heribert; Greenwood, Alex D; Czirják, Gábor Á

    2015-11-01

    The general development of immune response in the short and long term is a product of the antigenic environment in which a species resides. Colonization of a novel antigenic environment by a species would be expected to alter the immune system. Animals that successfully adapt their immune responses will successfully colonize new locations. However, founder events associated with colonization by limited numbers of individuals from a source population will constrain adaptability. How these contradicting forces shape immunity in widely distributed species is unknown. The western house mouse (Mus musculus domesticus) spread globally from the Indo-Pakistani cradle, often in association with human migration and settlement. In the present study, we tested the hypothesis that wild-derived outbred laboratory populations of house mice from their original range (Iran) and historically recent European invasive populations (from France and Germany) present differences in immune functional diversity corresponding to recent historical founder events in Europe and movement to novel antigenic environments. We found that (1) European mice had lower total white blood cell (WBC) counts but higher immunoglobulin E concentrations than their Iranian counterparts, and (2) there were no significant differences in the measured immunological parameters among European populations. The results indicate that founder events in European mice and selection pressure exerted by the composition of local parasitic helminth communities underlie the observed patterns. PMID:26205199

  5. Sound fields separation and reconstruction of irregularly shaped sources

    NASA Astrophysics Data System (ADS)

    Totaro, N.; Vigoureux, D.; Leclère, Q.; Lagneaux, J.; Guyader, J. L.

    2015-02-01

    Nowadays, the need of source identification methods is still growing and application cases are more and more complex. As a consequence, it is necessary to develop methods allowing us to reconstruct sound fields on irregularly shaped sources in reverberant or confined acoustic environment. The inverse Patch Transfer Functions (iPTF) method is suitable to achieve these objectives. Indeed, as the iPTF method is based on Green's identity and double measurements of pressure and particle velocity on a surface surrounding the source, it is independent of the acoustic environment. In addition, the finite element solver used to compute the patch transfer functions permits us to handle sources with 3D irregular shapes. In the present paper, two experimental applications on a flat plate and an oil pan have been carried out to show the performances of the method on real applications. As for all ill-posed problem, it is shown that the crucial point of this method is the choice of the parameter of the Tikhonov regularization, one of the most widely used in the literature. The classical L-curve strategy sometimes fails to choose the best solution. This issue is clearly explained and an adapted strategy combining L-curve and acoustic power conservation is proposed. The efficiency of this strategy is demonstrated on both applications and compared to results obtained with Generalized Cross Validation (GCV) technique.

  6. A Dynamic Mesh-Based Approach to Model Melting and Shape of an ESR Electrode

    NASA Astrophysics Data System (ADS)

    Karimi-Sibaki, E.; Kharicha, A.; Bohacek, J.; Wu, M.; Ludwig, A.

    2015-10-01

    This paper presents a numerical method to investigate the shape of tip and melt rate of an electrode during electroslag remelting process. The interactions between flow, temperature, and electromagnetic fields are taken into account. A dynamic mesh-based approach is employed to model the dynamic formation of the shape of electrode tip. The effect of slag properties such as thermal and electrical conductivities on the melt rate and electrode immersion depth is discussed. The thermal conductivity of slag has a dominant influence on the heat transfer in the system, hence on melt rate of electrode. The melt rate decreases with increasing thermal conductivity of slag. The electrical conductivity of slag governs the electric current path that in turn influences flow and temperature fields. The melting of electrode is a quite unstable process due to the complex interaction between the melt rate, immersion depth, and shape of electrode tip. Therefore, a numerical adaptation of electrode position in the slag has been implemented in order to achieve steady state melting. In fact, the melt rate, immersion depth, and shape of electrode tip are interdependent parameters of process. The generated power in the system is found to be dependent on both immersion depth and shape of electrode tip. In other words, the same amount of power was generated for the systems where the shapes of tip and immersion depth were different. Furthermore, it was observed that the shape of electrode tip is very similar for the systems running with the same ratio of power generation to melt rate. Comparison between simulations and experimental results was made to verify the numerical model.

  7. Feedforward-Feedback Hybrid Control for Magnetic Shape Memory Alloy Actuators Based on the Krasnosel'skii-Pokrovskii Model

    PubMed Central

    Zhou, Miaolei; Zhang, Qi; Wang, Jingyuan

    2014-01-01

    As a new type of smart material, magnetic shape memory alloy has the advantages of a fast response frequency and outstanding strain capability in the field of microdrive and microposition actuators. The hysteresis nonlinearity in magnetic shape memory alloy actuators, however, limits system performance and further application. Here we propose a feedforward-feedback hybrid control method to improve control precision and mitigate the effects of the hysteresis nonlinearity of magnetic shape memory alloy actuators. First, hysteresis nonlinearity compensation for the magnetic shape memory alloy actuator is implemented by establishing a feedforward controller which is an inverse hysteresis model based on Krasnosel'skii-Pokrovskii operator. Secondly, the paper employs the classical Proportion Integration Differentiation feedback control with feedforward control to comprise the hybrid control system, and for further enhancing the adaptive performance of the system and improving the control accuracy, the Radial Basis Function neural network self-tuning Proportion Integration Differentiation feedback control replaces the classical Proportion Integration Differentiation feedback control. Utilizing self-learning ability of the Radial Basis Function neural network obtains Jacobian information of magnetic shape memory alloy actuator for the on-line adjustment of parameters in Proportion Integration Differentiation controller. Finally, simulation results show that the hybrid control method proposed in this paper can greatly improve the control precision of magnetic shape memory alloy actuator and the maximum tracking error is reduced from 1.1% in the open-loop system to 0.43% in the hybrid control system. PMID:24828010

  8. A modular approach to adaptive structures.

    PubMed

    Pagitz, Markus; Pagitz, Manuel; Hühne, Christian

    2014-01-01

    A remarkable property of nastic, shape changing plants is their complete fusion between actuators and structure. This is achieved by combining a large number of cells whose geometry, internal pressures and material properties are optimized for a given set of target shapes and stiffness requirements. An advantage of such a fusion is that cell walls are prestressed by cell pressures which increases, decreases the overall structural stiffness, weight. Inspired by the nastic movement of plants, Pagitz et al (2012 Bioinspir. Biomim. 7) published a novel concept for pressure actuated cellular structures. This article extends previous work by introducing a modular approach to adaptive structures. An algorithm that breaks down any continuous target shapes into a small number of standardized modules is presented. Furthermore it is shown how cytoskeletons within each cell enhance the properties of adaptive modules. An adaptive passenger seat and an aircrafts leading, trailing edge is used to demonstrate the potential of a modular approach. PMID:25289521

  9. Rollercoaster Loop Shapes

    ERIC Educational Resources Information Center

    Pendrill, Ann-Marie

    2005-01-01

    Many modern rollercoasters feature loops. Although textbook loops are often circular, real rollercoaster loops are not. In this paper, we look into the mathematical description of various possible loop shapes, as well as their riding properties. We also discuss how a study of loop shapes can be used in physics education.

  10. Rollercoaster loop shapes

    NASA Astrophysics Data System (ADS)

    Pendrill, Ann-Marie

    2005-11-01

    Many modern rollercoasters feature loops. Although textbook loops are often circular, real rollercoaster loops are not. In this paper, we look into the mathematical description of various possible loop shapes, as well as their riding properties. We also discuss how a study of loop shapes can be used in physics education.

  11. Crystal Shape Bingo.

    ERIC Educational Resources Information Center

    Rule, Audrey C.

    This document describes a game that provides students with practice in recognizing three dimensional crystal shapes and planar geometric shapes of crystal faces. It contains information on the objective of the game, game preparation, and rules for playing. Play cards are included (four to a page). (ASK)

  12. On the potential of 2-D-Video Disdrometer technique to measure micro physical parameters of solid precipitation

    NASA Astrophysics Data System (ADS)

    Bernauer, F.; Hürkamp, K.; Rühm, W.; Tschiersch, J.

    2015-03-01

    Detailed characterization and classification of precipitation is an important task in atmospheric research. Line scanning 2-D-video disdrometer technique is well established for rain observations. The two orthogonal views taken of each hydrometeor passing the sensitive area of the instrument qualify this technique especially for detailed characterization of non symmetric solid hydrometeors. However, in case of solid precipitation problems related to the matching algorithm have to be considered and the user must be aware of the limited spacial resolution when size and shape descriptors are analyzed. This work has the aim of clarifying the potential of 2-D-video disdrometer technique in deriving size, velocity and shape parameters from single recorded pictures. The need of implementing a matching algorithm suitable for mixed and solid phase precipitation is highlighted as an essential step in data evaluation. For this purpose simple reproducible experiments with solid steel spheres and irregularly shaped styrofoam particles are conducted. Self-consistency of shape parameter measurements is tested in 40 cases of real snow fall. As result it was found, that reliable size and shape characterization with a relative standard deviation of less than 5% is only possible for particles larger than 1 mm. For particles between 0.5 and 1.0 mm the relative standard deviation can grow up to 22% for the volume, 17% for size parameters and 14% for shape descriptors. Testing the adapted matching algorithm with a reproducible experiment with styrofoam particles a mismatch probability of less than 2.5% was found. For shape parameter measurements in case of real solid phase precipitation the 2DVD shows self-consistent behavior.

  13. Laser welding of polymers: phenomenological model for a quick and reliable process quality estimation considering beam shape influences

    NASA Astrophysics Data System (ADS)

    Timpe, Nathalie F.; Stuch, Julia; Scholl, Marcus; Russek, Ulrich A.

    2016-03-01

    This contribution presents a phenomenological, analytical model for laser welding of polymers which is suited for a quick process quality estimation for the practitioner. Besides material properties of the polymer and processing parameters like welding pressure, feed rate and laser power the model is based on a simple few parameter description of the size and shape of the laser power density distribution (PDD) in the processing zone. The model allows an estimation of the weld seam tensile strength. It is based on energy balance considerations within a thin sheet with the thickness of the optical penetration depth on the surface of the absorbing welding partner. The joining process itself is modelled by a phenomenological approach. The model reproduces the experimentally known process windows for the main process parameters correctly. Using the parameters describing the shape of the laser PDD the critical dependence of the process windows on the PDD shape will be predicted and compared with experiments. The adaption of the model to other laser manufacturing processes where the PDD influence can be modelled comparably will be discussed.

  14. Pulse shaping system

    DOEpatents

    Skeldon, M.D.; Letzring, S.A.

    1999-03-23

    Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

  15. Pulse shaping system

    DOEpatents

    Skeldon, Mark D.; Letzring, Samuel A.

    1999-03-23

    Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

  16. Advancements in adaptive aerodynamic technologies for airfoils and wings

    NASA Astrophysics Data System (ADS)

    Jepson, Jeffrey Keith

    Although aircraft operate over a wide range of flight conditions, current fixed-geometry aircraft are optimized for only a few of these conditions. By altering the shape of the aircraft, adaptive aerodynamics can be used to increase the safety and performance of an aircraft by tailoring the aircraft for multiple flight conditions. Of the various shape adaptation concepts currently being studied, the use of multiple trailing-edge flaps along the span of a wing offers a relatively high possibility of being incorporated on aircraft in the near future. Multiple trailing-edge flaps allow for effective spanwise camber adaptation with resulting drag benefits over a large speed range and load alleviation at high-g conditions. The research presented in this dissertation focuses on the development of this concept of using trailing-edge flaps to tailor an aircraft for multiple flight conditions. One of the major tasks involved in implementing trailing-edge flaps is in designing the airfoil to incorporate the flap. The first part of this dissertation presents a design formulation that incorporates aircraft performance considerations in the inverse design of low-speed laminar-flow adaptive airfoils with trailing-edge cruise flaps. The benefit of using adaptive airfoils is that the size of the low-drag region of the drag polar can be effectively increased without increasing the maximum thickness of the airfoil. Two aircraft performance parameters are considered: level-flight maximum speed and maximum range. It is shown that the lift coefficients for the lower and upper corners of the airfoil low-drag range can be appropriately adjusted to tailor the airfoil for these two aircraft performance parameters. The design problem is posed as a part of a multidimensional Newton iteration in an existing conformal-mapping based inverse design code, PROFOIL. This formulation automatically adjusts the lift coefficients for the corners of the low-drag range for a given flap deflection as

  17. Fall velocity of multi-shaped clasts

    NASA Astrophysics Data System (ADS)

    Le Roux, Jacobus P.

    2014-12-01

    Accurate settling velocity predictions of differently shaped micro- or macroclasts are required in many branches of science and engineering. Here, a single, dimensionally correct equation is presented that yields a significant improvement on previous settling formulas for a wide range of clast shapes. For smooth or irregular clasts with known axial dimensions, a partially polynomial equation based on the logarithmic values of dimensionless sizes and settling velocities is presented, in which the values of only one coefficient and one exponent need to be adapted for different shapes, irrespective of the Reynolds number. For irregular, natural clasts with unknown axial dimensions, a polynomial equation of the same form is applied, but with different coefficients. Comparison of the predicted and measured settling velocities of 8 different shape classes as well as natural grains with unknown axial dimensions in liquids, representing a total of 390 experimental data points, shows a mean percentage error of - 0.83% and a combined R2 value of 0.998. The settling data of 169 differently shaped particles of pumice, glass and feldspar falling in air were also analyzed, which demonstrates that the proposed equation is also valid for these conditions. Two additional shape classes were identified in the latter data set, although the resultant equations are less accurate than for liquids. An Excel spreadsheet is provided to facilitate the calculation of fall velocities for grains settling individually and in groups, or alternatively to determine the equivalent sieve size from the settling velocity, which can be used to calibrate settling tubes.

  18. Beam shaping unit for micromachining

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Å iaulys, Nerijus; Å lekys, Gintas; Laskin, Vadim

    2013-09-01

    Uniform irradiance distribution of laser spot is highly advisable in various micromachining techniques like scribing, PCB and Through-Silicon Via (TSV) drilling, repair techniques in display making technologies. Scanning over whole working field with using popular 2- and 3-axis galvo mirror scanners is another important part of microprocessing systems. Therefore, combining of beam shaping optics, converting Gaussian to flattop (uniform) laser beam profile, with scanning optical heads is an insistent technical task. To provide flattop irradiance profile it is suggested to apply field mapping refractive beam shaping optics πShaper being characterized by some important features: low output divergence, high transmittance, extended depth of field, capability to work with TEM00 and multimode lasers, as result providing a freedom in building various optical systems. De-magnifying of flattop laser beam can be realized with using imaging technique; the imaging optical system to be composed from F-theta lens of scanning head and additional collimating system to be used right after a πShaper. One of the problems in this approach is implementation of compact design of the collimating part. As a solution it is suggested to apply a specially designed Beam Shaping Unit (BSU) to be installed between a laser and a scanning head and providing: conversion from Gaussian to flattop laser beam irradiance profile, compact collimator design, and functions of laser beam adjustment and adaptation to a laser and a scanning head used in particular equipment. There will be considered design features of refractive beam shapers πShaper and BSU, examples of optical layouts to generate flattop laser spots, which sizes span from several tens of microns to millimetres. Examples of real implementations and results of material processing will be presented as well.

  19. Beam shaping for holographic techniques

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Laskin, Vadim; Ostrun, Aleksei

    2014-09-01

    Uniform intensity of laser radiation is very important in holographic and interferometry technologies, therefore transformation of typical Gaussian distribution of a TEM00 laser to flat-top (top hat) is an actual technical task, it is solved by applying beam shaping optics. Holography and interferometry have specific requirements to a uniform laser beam, most important of them are flatness of phase front and extended depth of field. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality demanding holography and interferometry. We suggest applying refractive field mapping beam shapers piShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. This approach is used in SLM-based technologies of Computer Generated Holography, Dot-Matrix mastering of security holograms, holographic data storage, holographic projection, lithography, interferometric recording of Volume Bragg Gratings. High optical quality of resulting flat-top beam allows applying additional optical components to vary beam size and shape, thus adapting an optical system to requirements of a particular application. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in holographic systems. Examples of real implementations and experimental results will be presented as well.

  20. Thermoviscoplastic behaviors of anisotropic shape memory elastomeric composites for cold programmed non-affine shape change

    NASA Astrophysics Data System (ADS)

    Mao, Yiqi; Robertson, Jaimee M.; Mu, Xiaoming; Mather, Patrick T.; Jerry Qi, H.

    2015-12-01

    anisotropic viscoplastic property of the fibrous mat is captured by an isotropic fibrous network superimposed with an oriented fibrous network. The material parameters in the model are identified from the experiments on the fibrous mat and on the composites, respectively. The cold-programmed shape memory behaviors of the composite are predicted by simulations and compared with experiments without further adjusting the material parameters. Good agreement is observed, indicating the ability of the present model to capture the anisotropic viscoplastic and shape memory behaviors. By using the developed constitutive model, effects of loading rate and fiber volume fraction on cold programmed shape memory behavior are discussed. Furthermore, the constitutive relation is applied to a mechanical model to study the cold-programmed curling of the laminates.

  1. Adaptive Control Of Remote Manipulator

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun

    1989-01-01

    Robotic control system causes remote manipulator to follow closely reference trajectory in Cartesian reference frame in work space, without resort to computationally intensive mathematical model of robot dynamics and without knowledge of robot and load parameters. System, derived from linear multivariable theory, uses relatively simple feedforward and feedback controllers with model-reference adaptive control.

  2. Drawing an elephant with four complex parameters

    NASA Astrophysics Data System (ADS)

    Mayer, Jürgen; Khairy, Khaled; Howard, Jonathon

    2010-06-01

    We define four complex numbers representing the parameters needed to specify an elephantine shape. The real and imaginary parts of these complex numbers are the coefficients of a Fourier coordinate expansion, a powerful tool for reducing the data required to define shapes.

  3. Surface parametrization and shape description

    NASA Astrophysics Data System (ADS)

    Brechbuehler, Christian; Gerig, Guido; Kuebler, Olaf

    1992-09-01

    Procedures for the parameterization and description of the surface of simply connected 3-D objects are presented. Critical issues for shape-based categorization and comparison of 3-D objects are addressed, which are generality with respect to object complexity, invariance to standard transformations, and descriptive power in terms of object geometry. Starting from segmented volume data, a relational data structure describing the adjacency of local surface elements is generated. The representation is used to parametrize the surface by defining a continuous, one-to-one mapping from the surface of the original object to the surface of a unit sphere. The mapping is constrained by two requirements, minimization of distortions and preservation of area. The former is formulated as the goal function of a nonlinear optimization problem and the latter as its constraints. Practicable starting values are obtained by an initial mapping based on a heat conduction model. In contract to earlier approaches, the novel parameterization method provides a mapping of arbitrarily shaped simply connected objects, i.e., it performs an unfolding of convoluted surface structures. This global parameterization allows the systematical scanning of the object surface by the variation of two parameters. As one possible approach to shape analysis, it enables us to expand the object surface into a series of spherical harmonic functions, extending the concept of elliptical Fourier descriptors for 2-D closed curves. The novel parameterization overcomes the traditional limitations of expressing an object surface in polar coordinates, which restricts such descriptions to star-shaped objects. The numerical coefficients in the Fourier series form an object-centered, surface-oriented descriptor of the object''s form. Rotating the coefficients in parameter space and object space puts the object into a standard position and yields a spherical harmonic descriptor which is invariant to translations, rotations

  4. Reconstructing liver shape and position from MR image slices using an active shape model

    NASA Astrophysics Data System (ADS)

    Fenchel, Matthias; Thesen, Stefan; Schilling, Andreas

    2008-03-01

    We present an algorithm for fully automatic reconstruction of 3D position, orientation and shape of the human liver from a sparsely covering set of n 2D MR slice images. Reconstructing the shape of an organ from slice images can be used for scan planning, for surgical planning or other purposes where 3D anatomical knowledge has to be inferred from sparse slices. The algorithm is based on adapting an active shape model of the liver surface to a given set of slice images. The active shape model is created from a training set of liver segmentations from a group of volunteers. The training set is set up with semi-manual segmentations of T1-weighted volumetric MR images. Searching for the optimal shape model that best fits to the image data is done by maximizing a similarity measure based on local appearance at the surface. Two different algorithms for the active shape model search are proposed and compared: both algorithms seek to maximize the a-posteriori probability of the grey level appearance around the surface while constraining the surface to the space of valid shapes. The first algorithm works by using grey value profile statistics in normal direction. The second algorithm uses average and variance images to calculate the local surface appearance on the fly. Both algorithms are validated by fitting the active shape model to abdominal 2D slice images and comparing the shapes, which have been reconstructed, to the manual segmentations and to the results of active shape model searches from 3D image data. The results turn out to be promising and competitive to active shape model segmentations from 3D data.

  5. A role for membrane shape and information processing in cardiac physiology.

    PubMed

    Knöll, Ralph

    2015-01-01

    While the heart is a dynamic organ and one of its major functions is to provide the organism with sufficient blood supply, the regulatory feedback systems, which allow adaptation to hemodynamic changes, remain not well understood. Our current description of mechanosensation focuses on stretch-sensitive ion channels, cytoskeletal components, structures such as the sarcomeric Z-disc, costameres, caveolae, or the concept of tensegrity, but these models appear incomplete as the remarkable plasticity of the myocardium in response to biomechanical stress and heart rate variations remains unexplained. Signaling activity at membranes depends on their geometric parameters such as surface area and curvature, which links shape to information processing. In the heart, continuous cycles of contraction and relaxation reshape membrane morphology and hence affect cardio-mechanic signaling. This article provides a brief review on current models of mechanosensation and focuses on how signaling, cardiac myocyte dynamics, and membrane shape interact and potentially give rise to a self-organized system that uses shape to sense the extra- and intracellular environment. This novel concept may help to explain how changes in frequency, and thus membrane shape, affect cardiac plasticity. One of the conclusions is that hypertrophy and associated fibrosis, which have been considered as necessary to cope with increased wall stress, can also be seen as part of complex feedback systems which use local membrane inhomogeneity in different cardiac cell types to influence whole organphysiology and which are predicted to fine-tune and thus regulate membrane-mediated signaling. PMID:25129123

  6. Optical simulation of laser beam phase-shaping focusing optimization in biological tissues

    NASA Astrophysics Data System (ADS)

    Gomes, Ricardo; Vieira, Pedro; Coelho, João. M. P.

    2013-11-01

    In this paper we report the development of an optical simulator that can be used in the development of methodologies for compensate/decrease the light scattering effect of most biological tissues through phase-shaping methods. In fact, scattering has long been a major limitation for the medical applications of lasers where in-depth tissues concerns due to the turbid nature of most biological media in the human body. In developing the simulator, two different approaches were followed: one using multiple identical beams directed to the same target area and the other using a phase-shaped beam. In the multiple identical beams approach (used mainly to illustrate the limiting effect of scattering on the beam's propagation) there was no improvement in the beam focus at 1 mm compared to a single beam layout but, in phase-shaped beam approach, a 8x improvement on the radius of the beam at the same depth was achieved. The models were created using the optical design software Zemax and numerical algorithms created in Matlab programming language to shape the beam wavefront. A dedicated toolbox allowed communication between both programs. The use of the two software's proves to be a simple and powerful solution combining the best of the two and allowing a significant potential for adapting the simulations to new systems and thus allow to assess their response and define critical engineering parameters prior to laboratorial implementation.

  7. Shape and Color Features for Object Recognition Search

    NASA Technical Reports Server (NTRS)

    Duong, Tuan A.; Duong, Vu A.; Stubberud, Allen R.

    2012-01-01

    A bio-inspired shape feature of an object of interest emulates the integration of the saccadic eye movement and horizontal layer in vertebrate retina for object recognition search where a single object can be used one at a time. The optimal computational model for shape-extraction-based principal component analysis (PCA) was also developed to reduce processing time and enable the real-time adaptive system capability. A color feature of the object is employed as color segmentation to empower the shape feature recognition to solve the object recognition in the heterogeneous environment where a single technique - shape or color - may expose its difficulties. To enable the effective system, an adaptive architecture and autonomous mechanism were developed to recognize and adapt the shape and color feature of the moving object. The bio-inspired object recognition based on bio-inspired shape and color can be effective to recognize a person of interest in the heterogeneous environment where the single technique exposed its difficulties to perform effective recognition. Moreover, this work also demonstrates the mechanism and architecture of the autonomous adaptive system to enable the realistic system for the practical use in the future.

  8. Adaptive Gas Metal Arc (GMA) Welder

    NASA Astrophysics Data System (ADS)

    Nachev, G.; Petkov, B.; Blagoev, L.; Tsankarski, I.

    1984-02-01

    Unlike NC machine-tools, where the tool path is primary and the product shape results from it, in arc welding the product is primary, and the welder - human or robot - has to contend with poor fitups, bad preparations, inexact positionning etc. All this means one thing - adaptivity. The axtent to which this is reasonable is discussed, and then a research project, conducted at IICR with the aim to create an adaptive GMA robot, is presented.

  9. An adaptive spoiler to control the transonic shock

    NASA Astrophysics Data System (ADS)

    Bein, Th; Hanselka, H.; Breitbach, E.

    2000-04-01

    Market research predicts, for the aircraft industry, a large growth in the number of passengers as well as the airfreight rate with the result of this leading to increased competition for the European aircraft industry, the efficiency of new aircraft has to be improved drastically. One approach, among others, is the aerodynamic optimization of the wing. The fixed wing is designed optimally only for one flight condition. This flight condition is described by the parameters altitude, mach number and aircraft weight, all of which permanently vary during the mission of the aircraft. Therefore, the aircraft is just periodically near to the chosen design point. To compensate for this major disadvantage, an `adaptive wing' for optimal adaptation and variation of the profile geometry to the actual flight conditions will be developed. Daimler-Benz Aerospace Airbus, Daimler-Benz Research and the German Aerospace Center (DLR) are working as project partners on concepts for a variable camber and a local spoiler bump. In this paper a structural concept developed by the DLR for the adaptive spoiler will be presented. The concept is designed under the aspect of adaptive structural systems and requires a high integration of actuators, sensor and controllers in the structure. Special aspects of the design will be discussed and the first results, analytical, numerical as well as experimental, will be presented. Part of the concept design is also the development of new actuators optimized for the specific problem. A new actuator concept for the adaptive spoiler based on a cylindrical tube and activated either by pressure or multifunctional materials (e.g. shape memory alloys) will additionally be shown.

  10. Adaptive Modal Identification for Flutter Suppression Control

    NASA Technical Reports Server (NTRS)

    Nguyen, Nhan T.; Drew, Michael; Swei, Sean S.

    2016-01-01

    In this paper, we will develop an adaptive modal identification method for identifying the frequencies and damping of a flutter mode based on model-reference adaptive control (MRAC) and least-squares methods. The least-squares parameter estimation will achieve parameter convergence in the presence of persistent excitation whereas the MRAC parameter estimation does not guarantee parameter convergence. Two adaptive flutter suppression control approaches are developed: one based on MRAC and the other based on the least-squares method. The MRAC flutter suppression control is designed as an integral part of the parameter estimation where the feedback signal is used to estimate the modal information. On the other hand, the separation principle of control and estimation is applied to the least-squares method. The least-squares modal identification is used to perform parameter estimation.

  11. Adaptive Optics for Industry and Medicine

    NASA Astrophysics Data System (ADS)

    Dainty, Christopher

    2008-01-01

    at Iris AO (poster paper) / Michael A. Helmbrecht ... [et al.]. Electrostatic push pull mirror improvernents in visual optics (poster paper) / S. Bonora and L. Poletto. 25cm bimorph mirror for petawatt laser / S. Bonora ... [et al.]. Hysteresis compensation for piezo deformable mirror (poster paper) / H. Song ... [et al.]. Static and dynamic responses of an adaptive optics ferrofluidic mirror (poster paper) / A. Seaman ... [et al.]. New HDTV (1920 x 1080) phase-only SLM (poster paper) / Stefan Osten and Sven Krueger. Monomorph large aperture deformable mirror for laser applications (poster paper) / J-C Sinquin, J-M Lurcon, C. Guillemard. Low cost, high speed for adaptive optics control (oral paper) / Christopher D. Saunter and Gordon D. Love. Open loop woofer-tweeter adaptive control on the LAO multi-conjugate adaptive optics testbed (oral paper) / Edward Laag, Don Gavel and Mark Ammons -- pt. 2. Wavefront sensors. Wave front sensorless adaptive optics for imaging and microscopy (invited paper) / Martin J. Booth, Delphine Débarre and Tony Wilson. A fundamental limit for wavefront sensing (oral paper) / Carl Paterson. Coherent fibre-bundle wavefront sensor (oral paper) / Brian Vohnsen, I. Iglesias and Pablo Artal. Maximum-likelihood methods in wave-front sensing: nuisance parameters (oral paper) / David Lara, Harrison H. Barrett, and Chris Dainty. Real-time wavefront sensing for ultrafast high-power laser beams (oral paper) / Juan M. Bueno ... [et al.]. Wavefront sensing using a random phase screen (oral paper) / M. Loktev, G. Vdovin and O. Soloviev. Quadri-Wave Lateral Shearing Interferometry: a new mature technique for wave front sensing in adaptive optics (oral paper) / Benoit Wattellier ... [et al.]. In vivo measurement of ocular aberrations with a distorted grating wavefront sensor (oral paper) / P. Harrison ... [et al.]. Position-sensitive detector designed with unusual CMOS layout strategies for a Hartman-Shack wavefront sensor (oral Paper) / Davies W. de Lima

  12. Survey of adaptive control using Liapunov design

    NASA Technical Reports Server (NTRS)

    Lindorff, D. P.; Carroll, R. L.

    1973-01-01

    A survey of the literature in which Liapunov's second method is used in determining the control law is presented, with emphasis placed on the model-tracking adaptive control problem. Forty references are listed. Following a brief tutorial exposition of the adaptive control problem, the techniques for treating reduction of order, disturbance and time-varying parameters, multivariable systems, identification, and adaptive observers are discussed. The method is critically evaluated, particularly with respect to possibilities for application.

  13. Digital adaptive control laws for VTOL aircraft

    NASA Technical Reports Server (NTRS)

    Hartmann, G. L.; Stein, G.

    1979-01-01

    Honeywell has designed a digital self-adaptive flight control system for flight test in the VALT Research Aircraft (a modified CH-47). The final design resulted from a comparison of two different adaptive concepts: one based on explicit parameter estimates from a real-time maximum likelihood estimation algorithm and the other based on an implicit model reference adaptive system. The two designs are compared on the basis of performance and complexity.

  14. The Shapes of Physics

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2013-12-01

    I have used many ploys to start a course in introductory physics, but one of the more interesting ones was to spend 20 minutes describing some of the curves and shapes that we would encounter in our year together. The students saw parabolas, catenaries, hyperbolas, cycloids, circles, ellipses, and helices, and were shown examples, either live or on slides, of these shapes. The world of physics is three-dimensional, and students need to see what curves and trajectories span it. Once they see these shapes in nature, they look at the world around them in fresh ways.

  15. Shape memory polymer foams

    NASA Astrophysics Data System (ADS)

    Santo, Loredana

    2016-02-01

    Recent advances in shape memory polymer (SMP) foam research are reviewed. The SMPs belong to a new class of smart polymers which can have interesting applications in microelectromechanical systems, actuators and biomedical devices. They can respond to specific external stimulus changing their configuration and then remember the original shape. In the form of foams, the shape memory behaviour can be enhanced because they generally have higher compressibility. Considering also the low weight, and recovery force, the SMP foams are expected to have great potential applications primarily in aerospace. This review highlights the recent progress in characterization, evaluation, and proposed applications of SMP foams mainly for aerospace applications.

  16. Supergranular Parameters

    NASA Astrophysics Data System (ADS)

    Udayashankar, Paniveni

    2016-07-01

    I study the complexity of supergranular cells using intensity patterns from Kodaikanal solar observatory. The chaotic and turbulent aspect of the solar supergranulation can be studied by examining the interrelationships amongst the parameters characterizing supergranular cells namely size, horizontal flow field, lifetime and physical dimensions of the cells and the fractal dimension deduced from the size data. The findings are supportive of Kolmogorov's theory of turbulence. The Data consists of visually identified supergranular cells, from which a fractal dimension 'D' for supergranulation is obtained according to the relation P α AD/2 where 'A' is the area and 'P' is the perimeter of the supergranular cells. I find a fractal dimension close to about 1.3 which is consistent with that for isobars and suggests a possible turbulent origin. The cell circularity shows a dependence on the perimeter with a peak around (1.1-1.2) x 105 m. The findings are supportive of Kolmogorov's theory of turbulence.

  17. Towards Adaptive High-Resolution Images Retrieval Schemes

    NASA Astrophysics Data System (ADS)

    Kourgli, A.; Sebai, H.; Bouteldja, S.; Oukil, Y.

    2016-06-01

    Nowadays, content-based image-retrieval techniques constitute powerful tools for archiving and mining of large remote sensing image databases. High spatial resolution images are complex and differ widely in their content, even in the same category. All images are more or less textured and structured. During the last decade, different approaches for the retrieval of this type of images have been proposed. They differ mainly in the type of features extracted. As these features are supposed to efficiently represent the query image, they should be adapted to all kind of images contained in the database. However, if the image to recognize is somewhat or very structured, a shape feature will be somewhat or very effective. While if the image is composed of a single texture, a parameter reflecting the texture of the image will reveal more efficient. This yields to use adaptive schemes. For this purpose, we propose to investigate this idea to adapt the retrieval scheme to image nature. This is achieved by making some preliminary analysis so that indexing stage becomes supervised. First results obtained show that by this way, simple methods can give equal performances to those obtained using complex methods such as the ones based on the creation of bag of visual word using SIFT (Scale Invariant Feature Transform) descriptors and those based on multi scale features extraction using wavelets and steerable pyramids.

  18. Reduction in redundancy of multichannel telemetric information by the method of adaptive discretization with associative sorting

    NASA Technical Reports Server (NTRS)

    Kantor, A. V.; Timonin, V. G.; Azarova, Y. S.

    1974-01-01

    The method of adaptive discretization is the most promising for elimination of redundancy from telemetry messages characterized by signal shape. Adaptive discretization with associative sorting was considered as a way to avoid the shortcomings of adaptive discretization with buffer smoothing and adaptive discretization with logical switching in on-board information compression devices (OICD) in spacecraft. Mathematical investigations of OICD are presented.

  19. On-line adaptive battery impedance parameter and state estimation considering physical principles in reduced order equivalent circuit battery models. Part 1. Requirements, critical review of methods and modeling

    NASA Astrophysics Data System (ADS)

    Fleischer, Christian; Waag, Wladislaw; Heyn, Hans-Martin; Sauer, Dirk Uwe

    2014-08-01

    Lithium-ion battery systems employed in high power demanding systems such as electric vehicles require a sophisticated monitoring system to ensure safe and reliable operation. Three major states of the battery are of special interest and need to be constantly monitored, these include: battery state of charge (SoC), battery state of health (capcity fade determination, SoH), and state of function (power fade determination, SoF). In a series of two papers, we propose a system of algorithms based on a weighted recursive least quadratic squares parameter estimator, that is able to determine the battery impedance and diffusion parameters for accurate state estimation. The functionality was proven on different battery chemistries with different aging conditions. The first paper investigates the general requirements on BMS for HEV/EV applications. In parallel, the commonly used methods for battery monitoring are reviewed to elaborate their strength and weaknesses in terms of the identified requirements for on-line applications. Special emphasis will be placed on real-time capability and memory optimized code for cost-sensitive industrial or automotive applications in which low-cost microcontrollers must be used. Therefore, a battery model is presented which includes the influence of the Butler-Volmer kinetics on the charge-transfer process. Lastly, the mass transport process inside the battery is modeled in a novel state-space representation.

  20. A Predictive Analysis Approach to Adaptive Testing.

    ERIC Educational Resources Information Center

    Kirisci, Levent; Hsu, Tse-Chi

    The predictive analysis approach to adaptive testing originated in the idea of statistical predictive analysis suggested by J. Aitchison and I.R. Dunsmore (1975). The adaptive testing model proposed is based on parameter-free predictive distribution. Aitchison and Dunsmore define statistical prediction analysis as the use of data obtained from an…

  1. Maximum-Likelihood Fits to Histograms for Improved Parameter Estimation

    NASA Astrophysics Data System (ADS)

    Fowler, J. W.

    2014-08-01

    Straightforward methods for adapting the familiar statistic to histograms of discrete events and other Poisson distributed data generally yield biased estimates of the parameters of a model. The bias can be important even when the total number of events is large. For the case of estimating a microcalorimeter's energy resolution at 6 keV from the observed shape of the Mn K fluorescence spectrum, a poor choice of can lead to biases of at least 10 % in the estimated resolution when up to thousands of photons are observed. The best remedy is a Poisson maximum-likelihood fit, through a simple modification of the standard Levenberg-Marquardt algorithm for minimization. Where the modification is not possible, another approach allows iterative approximation of the maximum-likelihood fit.

  2. Reversible Shape Memory

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Li, Qiaoxi; Turner, Sara; Brosnan, Sarah; Tippets, Cary; Carrillo, Jan-Michael; Nykypnachuk, Dmytro; Gang, Oleg; Dobrynin, Andrey; Lopez, Rene; Ashby, Valerie; Sheiko, Sergei

    2014-03-01

    Reversible shape memory has been achieved on various shapes, e.g. hairpin, origami, coil, robotic gripper and flow rate control device, allowing for multiple switching between encoded shapes without applying any external force. Also, the reversible photonic structure molded in dielectric elastomers has been designed. Maximum reversibility can be achieved by tuning the crosslinking density and the degree of crystallinity of semi-crystalline elastomers. Different crystallization protocols including isothermal and cooling crystallization have been applied to develop a universal picture integrating different shape memory (SM) behaviors: conventional one-way SM, two-way reversible SM, and one-way reversible SM. Acknowledge financial support from the NSF DMR-1122483, DMR- 1004576, and DMR-1206957.

  3. Shape memory polyurethane nanocomposites

    NASA Astrophysics Data System (ADS)

    Cao, Feina

    Shape memory polymers are smart materials which can remember their original shapes. However, the low recovery stress and low mechanical strength limit the commercial applications of shape memory polymers. In this study, nanoclays were introduced to shape memory polyurethanes (SMPU) to augment these properties by enhance the network of SMPU. Several factors which influence the shape recovery stress were evaluated, including the nature of polymer chain by using different monomers, type of clay particles, extent of filler dispersion, clay content and deformation conditions. It was found that only reactive clay particles were well dispersed into polyurethane matrix by the tethering between --CH2CH 2OH functional groups in clay surfactants and polyurethane chains. Two different shape memory polyurethanes (Systems I & II) prepared by bulk polymerization were compared. The shape memory effect of System I was triggered by melting of the soft segment crystals, while that of System II was by glass transition of the soft segments. It was seen that the reactive clay particles dispersed well in both polyurethane matrices and augmented the recovery stress, e.g., 20% increase with 1 wt % nanoclay in System I and 40% increase with 5 wt % nanoclay in System II were observed. In System I, clay particles interfered with soft segment crystallization, and promoted phase mixing between the hard and soft segments, thus affecting the fixity and recovery ratio. Nevertheless, the soft segment crystallinity was still enough and in some cases increased due to stretching to exhibit excellent shape fixity and shape recovery ratio. The higher loading of clay particles accelerated the stress relaxation, resulting in reduction of recovery stress. In System II, no significant effect of clay particles in phase separation was observed, so there was no influence of clay on shape fixity and recovery ratio. The recovery stress increased with reactive nanoclay content. It was also found that the recovery

  4. A Bayesian Model of Sensory Adaptation

    PubMed Central

    Sato, Yoshiyuki; Aihara, Kazuyuki

    2011-01-01

    Recent studies reported two opposite types of adaptation in temporal perception. Here, we propose a Bayesian model of sensory adaptation that exhibits both types of adaptation. We regard adaptation as the adaptive updating of estimations of time-evolving variables, which determine the mean value of the likelihood function and that of the prior distribution in a Bayesian model of temporal perception. On the basis of certain assumptions, we can analytically determine the mean behavior in our model and identify the parameters that determine the type of adaptation that actually occurs. The results of our model suggest that we can control the type of adaptation by controlling the statistical properties of the stimuli presented. PMID:21541346

  5. A novel definition for quantification of mode shape complexity

    NASA Astrophysics Data System (ADS)

    Koruk, Hasan; Sanliturk, Kenan Y.

    2013-07-01

    Complex mode shapes are quite often encountered in structural dynamics. However, there is no universally accepted parameter for the quantification of mode shape complexity. After reviewing the existing methods, a novel approach is proposed in this paper in order to quantify mode shape complexity for general structures. The new parameter proposed in this paper is based on conservation of energy principle when a structure is vibrating at a specific mode during a period of vibration. The levels of complexity of the individual mode shapes of a sample structure are then quantified using the proposed new parameter and the other parameters available in the literature. The corresponding results are compared, the validity and the generality of the new parameter are demonstrated for various damping scenarios.

  6. On Characterizing Particle Shape

    NASA Technical Reports Server (NTRS)

    Ennis, Bryan J.; Rickman, Douglas; Rollins, A. Brent; Ennis, Brandon

    2014-01-01

    It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.

  7. Adaptive cellular response to osmotic stress in pig articular chondrocytes.

    PubMed

    Borghetti, P; Della Salda, L; De Angelis, E; Maltarello, M C; Petronini, P G; Cabassi, E; Marcato, P S; Maraldi, N M; Borghetti, A F

    1995-04-01

    The authors studied the effects of a wide range of medium osmolarities (from 0.28 osM (physiological osmolarity of plasma and synovial fluid) to 0.58 osM) by altering Na+ concentration in high density cultures of pig articular chondrocytes in order to analyze the behaviour of some functional and structural parameters during cell adaptation to these imposed changes in the ionic environment. Biochemical and morphological results indicated that, even if isolated from the tissue matrix and cultured in vitro, chondrocytes maintained active osmoregulation systems which are present in living conditions. They showed a similar biochemical and morphological behavior when cultured at 0.28 osM and 0.38 osM but they were able, with regard to protein synthesis, aminoacid transport and proliferation rates, to respond quickly and to adapt to 0.48 osM medium as well. On the contrary, the treatment at the highest osmolarity (0.58 osM) early altered these biochemical parameters and was detrimental or even gave rise to lethal damage during long-term treatment. Furthermore, while chondrocytes cultured in 0.28-0.38 osM medium maintained phenotypic characteristics in culture, the higher osmolarities (0.48-0.58 osM) caused morphological changes in cell populations resulting in loss of phenotypic cell stability as demonstrated by their taking on a fibroblast-like shape as well as a lack of ability to assembly matrix proteoglycans. PMID:7778094

  8. Geometric Morphometrics of Rodent Sperm Head Shape

    PubMed Central

    Varea Sánchez, María; Bastir, Markus; Roldan, Eduardo R. S.

    2013-01-01

    Mammalian spermatozoa, particularly those of rodent species, are extremely complex cells and differ greatly in form and dimensions. Thus, characterization of sperm size and, particularly, sperm shape represents a major challenge. No consensus exists on a method to objectively assess size and shape of spermatozoa. In this study we apply the principles of geometric morphometrics to analyze rodent sperm head morphology and compare them with two traditional morphometry methods, that is, measurements of linear dimensions and dimensions-derived parameters calculated using formulae employed in sperm morphometry assessments. Our results show that geometric morphometrics clearly identifies shape differences among rodent spermatozoa. It is also capable of discriminating between size and shape and to analyze these two variables separately. Thus, it provides an accurate method to assess sperm head shape. Furthermore, it can identify which sperm morphology traits differ between species, such as the protrusion or retraction of the base of the head, the orientation and relative position of the site of flagellum insertion, the degree of curvature of the hook, and other distinct anatomical features and appendices. We envisage that the use of geometric morphometrics may have a major impact on future studies focused on the characterization of sperm head formation, diversity of sperm head shape among species (and underlying evolutionary forces), the effects of reprotoxicants on changes in cell shape, and phenotyping of genetically-modified individuals. PMID:24312234

  9. Adaptive Optics for Industry and Medicine

    NASA Astrophysics Data System (ADS)

    Dainty, Christopher

    2008-01-01

    at Iris AO (poster paper) / Michael A. Helmbrecht ... [et al.]. Electrostatic push pull mirror improvernents in visual optics (poster paper) / S. Bonora and L. Poletto. 25cm bimorph mirror for petawatt laser / S. Bonora ... [et al.]. Hysteresis compensation for piezo deformable mirror (poster paper) / H. Song ... [et al.]. Static and dynamic responses of an adaptive optics ferrofluidic mirror (poster paper) / A. Seaman ... [et al.]. New HDTV (1920 x 1080) phase-only SLM (poster paper) / Stefan Osten and Sven Krueger. Monomorph large aperture deformable mirror for laser applications (poster paper) / J-C Sinquin, J-M Lurcon, C. Guillemard. Low cost, high speed for adaptive optics control (oral paper) / Christopher D. Saunter and Gordon D. Love. Open loop woofer-tweeter adaptive control on the LAO multi-conjugate adaptive optics testbed (oral paper) / Edward Laag, Don Gavel and Mark Ammons -- pt. 2. Wavefront sensors. Wave front sensorless adaptive optics for imaging and microscopy (invited paper) / Martin J. Booth, Delphine Débarre and Tony Wilson. A fundamental limit for wavefront sensing (oral paper) / Carl Paterson. Coherent fibre-bundle wavefront sensor (oral paper) / Brian Vohnsen, I. Iglesias and Pablo Artal. Maximum-likelihood methods in wave-front sensing: nuisance parameters (oral paper) / David Lara, Harrison H. Barrett, and Chris Dainty. Real-time wavefront sensing for ultrafast high-power laser beams (oral paper) / Juan M. Bueno ... [et al.]. Wavefront sensing using a random phase screen (oral paper) / M. Loktev, G. Vdovin and O. Soloviev. Quadri-Wave Lateral Shearing Interferometry: a new mature technique for wave front sensing in adaptive optics (oral paper) / Benoit Wattellier ... [et al.]. In vivo measurement of ocular aberrations with a distorted grating wavefront sensor (oral paper) / P. Harrison ... [et al.]. Position-sensitive detector designed with unusual CMOS layout strategies for a Hartman-Shack wavefront sensor (oral Paper) / Davies W. de Lima

  10. Interference between adaptation to double steps and adaptation to rotated feedback in spite of differences in directional selectivity.

    PubMed

    Schmitz, Gerd

    2016-06-01

    Two key features of sensorimotor adaptation are the directional selectivity of adaptive changes and the interference of adaptations to opposite directions. The present study investigated whether directional selectivity and interference of adaptation are related to executive functions and whether these phenomena differ between two methods for visuomotor adaptation. Subjects adapted at three target directions to clockwise or counterclockwise rotated feedback or to clockwise or counterclockwise target displacements (double steps). Both adaptation methods induce rotations of movement trajectories into the same direction, but provide visual information differently. The results showed that adaptation progressed differently between three targets. When movements adapted clockwise, adaptation was best at the most clockwise located target, and when movements adapted counterclockwise, it was best at the most counterclockwise located target, suggesting that spatial generalization between target directions is related to the direction of motor adaptation. The two adaptation methods produced different adaptation patterns, which indicate a further impact of visual information. A second adaptation to the other and opposite-directed discordance was worse than naive adaptation and washed out the aftereffects from the first adaptation, confirming that both adaptation methods interfered. Executive functions were significant covariate for overall interference and interference of target-specific adaptation. The results suggest that directional selectivity of adaptation is shaped by the direction of motor adaptation and the visual information provided. The interference of both adaptation methods indicates that they share adaptive mechanisms for recalibration. The interference is the lower the better subjects are able to cognitively switch between tasks and to inhibit prepotent responses. Therefore, cognitive functions seem to be involved in the inhibition of non-adequate sensorimotor

  11. Arbitrary Shape Deformation in CFD Design

    NASA Technical Reports Server (NTRS)

    Landon, Mark; Perry, Ernest

    2014-01-01

    Sculptor(R) is a commercially available software tool, based on an Arbitrary Shape Design (ASD), which allows the user to perform shape optimization for computational fluid dynamics (CFD) design. The developed software tool provides important advances in the state-of-the-art of automatic CFD shape deformations and optimization software. CFD is an analysis tool that is used by engineering designers to help gain a greater understanding of the fluid flow phenomena involved in the components being designed. The next step in the engineering design process is to then modify, the design to improve the components' performance. This step has traditionally been performed manually via trial and error. Two major problems that have, in the past, hindered the development of an automated CFD shape optimization are (1) inadequate shape parameterization algorithms, and (2) inadequate algorithms for CFD grid modification. The ASD that has been developed as part of the Sculptor(R) software tool is a major advancement in solving these two issues. First, the ASD allows the CFD designer to freely create his own shape parameters, thereby eliminating the restriction of only being able to use the CAD model parameters. Then, the software performs a smooth volumetric deformation, which eliminates the extremely costly process of having to remesh the grid for every shape change (which is how this process had previously been achieved). Sculptor(R) can be used to optimize shapes for aerodynamic and structural design of spacecraft, aircraft, watercraft, ducts, and other objects that affect and are affected by flows of fluids and heat. Sculptor(R) makes it possible to perform, in real time, a design change that would manually take hours or days if remeshing were needed.

  12. Shapes of Interacting RNA Complexes

    PubMed Central

    Fu, Benjamin M.M.

    2014-01-01

    Abstract Shapes of interacting RNA complexes are studied using a filtration via their topological genus. A shape of an RNA complex is obtained by (iteratively) collapsing stacks and eliminating hairpin loops. This shape projection preserves the topological core of the RNA complex, and for fixed topological genus there are only finitely many such shapes. Our main result is a new bijection that relates the shapes of RNA complexes with shapes of RNA structures. This allows for computing the shape polynomial of RNA complexes via the shape polynomial of RNA structures. We furthermore present a linear time uniform sampling algorithm for shapes of RNA complexes of fixed topological genus. PMID:25075750

  13. Blocking reduction of Landsat Thematic Mapper JPEG browse images using optimal PSNR estimated spectra adaptive postfiltering

    NASA Technical Reports Server (NTRS)

    Linares, Irving; Mersereau, Russell M.; Smith, Mark J. T.

    1994-01-01

    Two representative sample images of Band 4 of the Landsat Thematic Mapper are compressed with the JPEG algorithm at 8:1, 16:1 and 24:1 Compression Ratios for experimental browsing purposes. We then apply the Optimal PSNR Estimated Spectra Adaptive Postfiltering (ESAP) algorithm to reduce the DCT blocking distortion. ESAP reduces the blocking distortion while preserving most of the image's edge information by adaptively postfiltering the decoded image using the block's spectral information already obtainable from each block's DCT coefficients. The algorithm iteratively applied a one dimensional log-sigmoid weighting function to the separable interpolated local block estimated spectra of the decoded image until it converges to the optimal PSNR with respect to the original using a 2-D steepest ascent search. Convergence is obtained in a few iterations for integer parameters. The optimal logsig parameters are transmitted to the decoder as a negligible byte of overhead data. A unique maxima is guaranteed due to the 2-D asymptotic exponential overshoot shape of the surface generated by the algorithm. ESAP is based on a DFT analysis of the DCT basis functions. It is implemented with pixel-by-pixel spatially adaptive separable FIR postfilters. PSNR objective improvements between 0.4 to 0.8 dB are shown together with their corresponding optimal PSNR adaptive postfiltered images.

  14. Optimization-based wavefront sensorless adaptive optics for multiphoton microscopy.

    PubMed

    Antonello, Jacopo; van Werkhoven, Tim; Verhaegen, Michel; Truong, Hoa H; Keller, Christoph U; Gerritsen, Hans C

    2014-06-01

    Optical aberrations have detrimental effects in multiphoton microscopy. These effects can be curtailed by implementing model-based wavefront sensorless adaptive optics, which only requires the addition of a wavefront shaping device, such as a deformable mirror (DM) to an existing microscope. The aberration correction is achieved by maximizing a suitable image quality metric. We implement a model-based aberration correction algorithm in a second-harmonic microscope. The tip, tilt, and defocus aberrations are removed from the basis functions used for the control of the DM, as these aberrations induce distortions in the acquired images. We compute the parameters of a quadratic polynomial that is used to model the image quality metric directly from experimental input-output measurements. Finally, we apply the aberration correction by maximizing the image quality metric using the least-squares estimate of the unknown aberration. PMID:24977374

  15. Self-adaptive genetic algorithms with simulated binary crossover.

    PubMed

    Deb, K; Beyer, H G

    2001-01-01

    Self-adaptation is an essential feature of natural evolution. However, in the context of function optimization, self-adaptation features of evolutionary search algorithms have been explored mainly with evolution strategy (ES) and evolutionary programming (EP). In this paper, we demonstrate the self-adaptive feature of real-parameter genetic algorithms (GAs) using a simulated binary crossover (SBX) operator and without any mutation operator. The connection between the working of self-adaptive ESs and real-parameter GAs with the SBX operator is also discussed. Thereafter, the self-adaptive behavior of real-parameter GAs is demonstrated on a number of test problems commonly used in the ES literature. The remarkable similarity in the working principle of real-parameter GAs and self-adaptive ESs shown in this study suggests the need for emphasizing further studies on self-adaptive GAs. PMID:11382356

  16. Evaluating two sparse grid surrogates and two adaptation criteria for groundwater Bayesian uncertainty quantification

    NASA Astrophysics Data System (ADS)

    Zeng, Xiankui; Ye, Ming; Burkardt, John; Wu, Jichun; Wang, Dong; Zhu, Xiaobin

    2016-04-01

    Sparse grid (SG) stochastic collocation methods have been recently used to build accurate but cheap-to-run surrogates for groundwater models to reduce the computational burden of Bayesian uncertainty analysis. The surrogates can be built for either a log-likelihood function or state variables such as hydraulic head and solute concentration. Using a synthetic groundwater flow model, this study evaluates the log-likelihood and head surrogates in terms of the computational cost of building them, the accuracy of the surrogates, and the accuracy of the distributions of model parameters and predictions obtained using the surrogates. The head surrogates outperform the log-likelihood surrogates for the following four reasons: (1) the shape of the head response surface is smoother than that of the log-likelihood response surface in parameter space, (2) the head variation is smaller than the log-likelihood variation in parameter space, (3) the interpolation error of the head surrogates does not accumulate to be larger than the interpolation error of the log-likelihood surrogates, and (4) the model simulations needed for building one head surrogate can be recycled for building others. For both log-likelihood and head surrogates, adaptive sparse grids are built using two indicators: absolute error and relative error. The adaptive head surrogates are insensitive to the error indicators, because the ratio between the two indicators is hydraulic head, which has small variation in the parameter space. The adaptive log-likelihood surrogates based on the relative error indicators outperform those based on the absolute error indicators, because adaptation based on the relative error indicator puts more sparse-grid nodes in the areas in the parameter space where the log-likelihood is high. While our numerical study suggests building state-variable surrogates and using the relative error indicator for building log-likelihood surrogates, selecting appropriate type of surrogates and

  17. Neural adaptation to thin and fat bodies in the fusiform body area and middle occipital gyrus: an fMRI adaptation study.

    PubMed

    Hummel, Dennis; Rudolf, Anne K; Brandi, Marie-Luise; Untch, Karl-Heinz; Grabhorn, Ralph; Hampel, Harald; Mohr, Harald M

    2013-12-01

    Visual perception can be strongly biased due to exposure to specific stimuli in the environment, often causing neural adaptation and visual aftereffects. In this study, we investigated whether adaptation to certain body shapes biases the perception of the own body shape. Furthermore, we aimed to evoke neural adaptation to certain body shapes. Participants completed a behavioral experiment (n = 14) to rate manipulated pictures of their own bodies after adaptation to demonstratively thin or fat pictures of their own bodies. The same stimuli were used in a second experiment (n = 16) using functional magnetic resonance imaging (fMRI) adaptation. In the behavioral experiment, after adapting to a thin picture of the own body participants also judged a thinner than actual body picture to be the most realistic and vice versa, resembling a typical aftereffect. The fusiform body area (FBA) and the right middle occipital gyrus (rMOG) show neural adaptation to specific body shapes while the extrastriate body area (EBA) bilaterally does not. The rMOG cluster is highly selective for bodies and perhaps body parts. The findings of the behavioral experiment support the existence of a perceptual body shape aftereffect, resulting from a specific adaptation to thin and fat pictures of one's own body. The fMRI results imply that body shape adaptation occurs in the FBA and the rMOG. The role of the EBA in body shape processing remains unclear. The results are also discussed in the light of clinical body image disturbances. PMID:22807338

  18. Static shape control for flexible structures

    NASA Technical Reports Server (NTRS)

    Rodriguez, G.; Scheid, R. E., Jr.

    1986-01-01

    An integrated methodology is described for defining static shape control laws for large flexible structures. The techniques include modeling, identifying and estimating the control laws of distributed systems characterized in terms of infinite dimensional state and parameter spaces. The models are expressed as interconnected elliptic partial differential equations governing a range of static loads, with the capability of analyzing electromagnetic fields around antenna systems. A second-order analysis is carried out for statistical errors, and model parameters are determined by maximizing an appropriate defined likelihood functional which adjusts the model to observational data. The parameter estimates are derived from the conditional mean of the observational data, resulting in a least squares superposition of shape functions obtained from the structural model.

  19. Robust impedance shaping telemanipulation

    SciTech Connect

    Colgate, J.E.

    1993-08-01

    When a human operator performs a task via a bilateral manipulator, the feel of the task is embodied in the mechanical impedance of the manipulator. Traditionally, a bilateral manipulator is designed for transparency; i.e., so that the impedance reflected through the manipulator closely approximates that of the task. Impedance shaping bilateral control, introduced here, differs in that it treats the bilateral manipulator as a means of constructively altering the impedance of a task. This concept is particularly valuable if the characteristic dimensions (e.g., force, length, time) of the task impedance are very different from those of the human limb. It is shown that a general form of impedance shaping control consists of a conventional power-scaling bilateral controller augmented with a real-time interactive task simulation (i.e., a virtual environment). An approach to impedance shaping based on kinematic similarity between tasks of different scale is introduced and illustrated with an example. It is shown that an important consideration in impedance shaping controller design is robustness; i.e., guaranteeing the stability of the operator/manipulator/task system. A general condition for the robustness of a bilateral manipulator is derived. This condition is based on the structured singular value ({mu}). An example of robust impedance shaping bilateral control is presented and discussed.

  20. Technical Seminar "Shape Memory Alloys"

    NASA Video Gallery

    Shape memory alloys are a unique group of materials that remember their original shape and return to that shape after being strained. How could the aerospace, automotive, and energy exploration ind...